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  • 1.
    Aasa, Jenny
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Vare, Daniel
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Motwani, Hitesh V.
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Jenssen, Dag
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Törnqvist, Margareta
    Stockholm University, Faculty of Science, Department of Environmental Science and Analytical Chemistry.
    Quantification of the mutagenic potency and repair of glycidol-induced DNA lesions2016In: Mutation research. Genetic toxicology and environmental mutagenesis, ISSN 1383-5718, E-ISSN 1879-3592, Vol. 805, p. 38-45Article in journal (Refereed)
    Abstract [en]

    Glycidol (Gly) is an electrophilic low-molecular weight epoxide that is classified by IARC as probably carcinogenic to humans. Humans might be exposed to Gly from food, e.g. refined vegetable oils, where Gly has been found as a food process contaminant. It is therefore important to investigate and quantify the genotoxicity of Gly as a primary step towards cancer risk assessment of the human exposure. Here, quantification of the mutagenic potency expressed per dose (AUC: area under the concentration time curve) of Gly has been performed in Chinese hamster ovary (CHO) cells, using the HPRT assay. The dose of Gly was estimated in the cell exposure medium by trapping Gly with a strong nucleophile, cob(I)alamin, to form stable cobalamin adducts for analysis by LC-MS/MS. Gly was stable in the exposure medium during the time for cell treatment, and thus the dose in vitro is the initial concentration x cell treatment time. Gly induced mutations in the hprt-gene at ante of 0.08 +/- 0:01 mutations/10(5) cells/mMh. Through comparison with the effect of ionizing radiation in the same system a relative mutagenic potency of 9.5 rad-eq./mMh was obtained, which could be used for comparison of genotoxicity of chemicals and between test systems and also in procedures for quantitative cancer risk assessment. Gly was shown to induce strand breaks, that were repaired by base excision repair. Furthermore, Gly-induced lesions, present during replication, were found to delay the replication fork elongation. From experiments with repair deficient cells, homologous recombination repair and the ERCC1-XPF complex were indicated to be recruited to support in the repair of the damage related to the stalled replication elongation. The type of DNA damage responsible for the mutagenic effect of Gly could not be concluded from the present study.

  • 2.
    Abramsson-Zetterberg, Lilianne
    et al.
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Ilback, Nils-Gunnar
    The synthetic food colouring agent Allura Red AC (E129) is not genotoxic in a flow cytometry-based micronucleus assay in vivo2013In: Food and Chemical Toxicology, ISSN 0278-6915, E-ISSN 1873-6351, Vol. 59, p. 86-89Article in journal (Refereed)
    Abstract [en]

    The safety of several azo colouring agents, used as food additives, has during the years been questioned. Allura Red AC (E129) has in some publications been classified as genotoxic. In fact, in the European Union, Allura Red is permitted as a food additive in human food, but, surprisingly, it was not acceptable as an additive for use in animal feed. In this study we have evaluated whether Allura Red is genotoxic using a flow cytometer-based micronucleus assay in peripheral blood of mice. Male FVB mice were given a single intra-peritoneal injection of various doses of Allura Red and sacrificed at 46 h after treatment. The tested doses were 0, 100, 200, 400, 600, 800, 1000, 1500, and 2000 mg/kg body weight (b.w.). Each dose group constituted three mice, except for in the dose group of 1000 mg/kg b.w., which constituted four mice. Blood samples were collected and the frequency of micronucleated polychromatic erythrocytes (fMNPCE) and the cell proliferation (%PCE) was determined. The analyses did not show any significant difference in the %PCE or in the fMNPCE. Consequently, under the testing circumstances one can conclude that Allura Red is not genotoxic.

  • 3.
    Abreu-Vieira, Gustavo
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Regulation and measurement of brown adipose tissue blood flow2014Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Brown adipose tissue (BAT) is an organ specialized in macromolecule combustion in order to produce heat. Because of its high capacity to dissipate energy, it is currently among the best hopes for future treatments of obesity and diabetes. BAT is permeated by a vast capillary network that delivers blood rich in oxygen and nutrients to supply the high metabolic needs of the tissue. At the same time, metabolites, carbon dioxide and warm blood are drained back into systemic circulation. Blood flow is in fact a limiting factor for thermogenesis. Therefore, understanding BAT blood flow regulation is a crucial step for describing the tissue function. This thesis aims to summarize anatomical descriptions, to discuss the methodological evolution of the field, and to synthetize what we have learned about mechanistic regulation of BAT blood flow during the last half century. Manuscript I introduces a new method (high-resolution laser-doppler imaging) for the measurement of BAT blood flow, and gives mechanistic insights about its physiological regulation. Manuscript II focuses on the influence of bombesin receptor subtype-3 on the neurological control of body temperature and thermogenesis.

  • 4.
    Abreu-Vieira, Gustavo
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Thermal physiology and metabolism: Interplay between heat generation and energy homeostasis2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Mammal metabolism is intimately connected to the maintenance of body temperature. While metabolic pathways invariably produce heat as a by-product, the natural heat present in the environment also plays a role in defining the adaptive metabolism and general physiology of an organism. This thesis aims to discuss basic aspects of energy expenditure and their interactions with energy stores and body composition. In Paper I, we apply a new technique – high-resolution laser-Doppler imaging – to describe physiological regulatory features of adrenergically-stimulated blood flow in brown adipose tissue, and evaluate the validity of blood flow as a parameter to estimate nonshivering thermogenesis. Paper II focuses on the central regulation of body temperature. In the absence of bombesin receptor subtype-3, mice present an altered neurological body temperature setpoint, while peripheral thermogenic capacity remains intact. We conclude that brown adipose tissue malfunction is not the cause of the hypothermia observed in this mouse model. Paper III incorporates measurements of body temperature to the energy expenditure of different sources: basal metabolic rate, physical activity, thermic effect of food, and cold-induced thermogenesis. We describe basic aspects of dynamic insulation, energetic costs of circadian variation and hypothesize that physical activity may change the body temperature setpoint. Paper IV describes methodological issues related to glucose tolerance tests in obese mice. We conclude that the erroneous scaling of doses may affect the interpretation of metabolic health in mouse models, and suggest a new methodology. Paper V describes the outcomes caused by the expression of the human Cidea protein in adipose tissue of mice and suggests that this protein may clarify the link between adipose tissue expansion and healthy obesity. Paper VI explores the dissociation between thiazolidinedione-induced adipose tissue “browning” and reduced blood glycaemia. We demonstrate that although this pharmacological class tends to induce some level of brown adipose tissue recruitment, this phenomenon does not define its antidiabetic effects.

  • 5.
    Abreu-Vieira, Gustavo
    et al.
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Bengtsson, Tore
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Petrovic, Natasa
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Nedergaard, Jan
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    On adequate procedures for glucose tolerance tests in obese animals: Measurement of glucose tolerance in obesityManuscript (preprint) (Other academic)
    Abstract [en]

    Routine procedures for glucose tolerance test in rodents utilize an amount of injected glucose that is proportional to total body weight (normally 2 mg per g body weight). Obese mice consist of much more chemically inert lipid than lean mice but have only marginal increases in lean body mass (the only compartment where glucose is distributed). Present procedures thus inevitably lead to a diagnosis of impaired glucose tolerance and enhanced insulin levels in obesity. Routine procedures should use fixed glucose amounts per lean body mass (or per mouse).

  • 6.
    Abreu-Vieira, Gustavo
    et al.
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Fischer, Alexander W.
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute. University of Hamburg, Germany.
    Mattsson, Charlotte
    de Jong, Jasper M. A.
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Shabalina, Irina G.
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Ryden, Mikael
    Laurencikiene, Jurga
    Arner, Peter
    Cannon, Barbara
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Nedergaard, Jan
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Petrovic, Natasa
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Cidea improves the metabolic profile through expansion of adipose tissue2015In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 6, article id 7433Article in journal (Refereed)
    Abstract [en]

    In humans, Cidea (cell death-inducing DNA fragmentation factor alpha-like effector A) is highly but variably expressed in white fat, and expression correlates with metabolic health. Here we generate transgenic mice expressing human Cidea in adipose tissues (aP2-hCidea mice) and show that Cidea is mechanistically associated with a robust increase in adipose tissue expandability. Under humanized conditions (thermoneutrality, mature age and prolonged exposure to high-fat diet), aP2-hCidea mice develop a much more pronounced obesity than their wild-type littermates. Remarkably, the malfunctioning of visceral fat normally caused by massive obesity is fully overcome-perilipin 1 and Akt expression are preserved, tissue degradation is prevented, macrophage accumulation is decreased and adiponectin expression remains high. Importantly, the aP2-hCidea mice display enhanced insulin sensitivity. Our data establish a functional role for Cidea and suggest that, in humans, the association between Cidea levels in white fat and metabolic health is not only correlative but also causative.

  • 7.
    Abreu-Vieira, Gustavo
    et al.
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Hagberg, Carolina E.
    Spalding, Kirsty L.
    Cannon, Barbara
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Nedergaard, Jan
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Adrenergically-stimulated blood flow in brown adipose tissue is not dependent on thermogenesis: Regulation of brown adipose tissue blood flow2015In: American Journal of Physiology. Endocrinology and Metabolism, ISSN 0193-1849, E-ISSN 1522-1555, Vol. 308, no 9, p. E822-E829Article in journal (Refereed)
    Abstract [en]

    Brown adipose tissue (BAT) thermogenesis relies on blood flow to be supplied with nutrients and oxygen, and for the distribution of the generated heat to the rest of the body. It is therefore fundamental to understand the mechanisms by which blood flow is regulated and its relation to thermogenesis. Here we present high-resolution laser-Doppler imaging (HR-LDR) as a novel method for noninvasive, in vivo measurement of BAT blood flow in mice. Using HR-LDR, we found that norepinephrine stimulation increases BAT blood flow in a dose-dependent manner, and that this response is profoundly modulated by environmental temperature acclimation. Surprisingly, we found that mice lacking uncoupling protein 1 (UCP1) have fully preserved BAT blood flow response to norepinephrine, despite failing to perform thermogenesis. BAT blood flow was not directly correlated to systemic glycaemia, but glucose injections could transiently increase tissue perfusion. Inguinal white adipose tissue, also known as a brite/beige adipose tissue, was also sensitive to cold acclimation and similarly increased blood flow in response to norepinephrine. In conclusion, using a novel non-invasive method to detect BAT perfusion, we demonstrate that adrenergically-stimulated BAT blood flow is qualitatively and quantitatively fully independent of thermogenesis, and is therefore not a reliable parameter for the estimation of BAT activation and heat generation.

  • 8.
    Abreu-Vieira, Gustavo
    et al.
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Kalinovich, Anastasia
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Cannon, Barbara
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Nedergaard, Jan
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Novel thiazolidinediones distinguish between (UCP1-independent) antidiabetic effects (MSDC-0602) and adipogenic and browning-inducing effects (MSDC-0160) of classical thiazolidinediones (rosiglitazone)Manuscript (preprint) (Other academic)
    Abstract [en]

    Thiazolinediones (TZDs), also called glitazones, are a class of drugs traditionally used forimproving glucose tolerance in type II diabetes mellitus. The beneficial effects ofthiazolidinedione are believed to be caused by the drug binding to the nuclear receptor PPARγ,which in turn triggers a general adipogenic program in white adipose tissue, and apparentthermogenic recruitment of brown and brite/beige fat. Here, we present a comparison of thephysiological effects of three thiazolidinediones (rosiglitazone, MSDC-0602, and MSDC-0160)in C57BL/6 mice fed high-fat diet and housed at thermoneutrality. Rosiglitazone and MSDC-0160 caused the classically-described thiazolidinedione effects of increased fat mass,hyperphagia, and increased UCP1 levels in brown adipose tissue. MSDC-0602 and rosiglitazoneimproved glucose tolerance but MSDC-0602 did not induce increased fat mass, hyperphagia, orincreased UCP1 levels in brown fat. The beneficial effects of thiazolidinediones were fullypresent even in UCP1-KO mice, providing evidence for a dissociation between thiazolidinedioneinducedadipose tissue browning and their antidiabetic effects. We conclude that even structurallysimilar thiazolidinediones can act through distinct pathways, and that the glucose-loweringeffects of this class do not seem to rely on PPAR-γ-induced browning of adipose tissues.

  • 9.
    Abreu-Vieira, Gustavo
    et al.
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute. National Institute of Diabetes and Digestive and Kidney Diseases, NIH, USA.
    Xiao, Cuiying
    Gavrilova, Oksana
    Reitman, Marc L.
    Integration of body temperature into the analysis of energy expenditure in the mouse2015In: Molecular Metabolism, ISSN 2212-8778, Vol. 4, no 6, p. 461-470Article in journal (Refereed)
    Abstract [en]

    Objectives: We quantified the effect of environmental temperature on mouse energy homeostasis and body temperature.Methods: The effect of environmental temperature (4e33 C) on body temperature, energy expenditure, physical activity, and food intake invarious mice (chow diet, high-fat diet, Brs3-/y, lipodystrophic) was measured using continuous monitoring.Results: Body temperature depended most on circadian phase and physical activity, but also on environmental temperature. The amounts ofenergy expenditure due to basal metabolic rate (calculated via a novel method), thermic effect of food, physical activity, and cold-inducedthermogenesis were determined as a function of environmental temperature. The measured resting defended body temperature matchedthat calculated from the energy expenditure using Fourier’s law of heat conduction. Mice defended a higher body temperature during physicalactivity. The cost of the warmer body temperature during the active phase is 4e16% of total daily energy expenditure. Parameters measured indiet-induced obese and Brs3-/y mice were similar to controls. The high post-mortem heat conductance demonstrates that most insulation in miceis via physiological mechanisms.Conclusions: At 22 C, cold-induced thermogenesis isw120% of basal metabolic rate. The higher body temperature during physical activity isdue to a higher set point, not simply increased heat generation during exercise. Most insulation in mice is via physiological mechanisms, with littlefrom fur or fat. Our analysis suggests that the definition of the upper limit of the thermoneutral zone should be re-considered. Measuring bodytemperature informs interpretation of energy expenditure data and improves the predictiveness and utility of the mouse to model human energyhomeostasis.

  • 10.
    Adam, Lucille
    et al.
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    López-González, Moisés
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Björk, Albin
    Pålsson, Sandra
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Poux, Candice
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Wahren-Herlenius, Marie
    Fernández, Carmen
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Spetz, Anna-Lena
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Early Resistance of Non-virulent Mycobacterial Infection in C57BL/6 Mice Is Associated With Rapid Up-Regulation of Antimicrobial Cathelicidin Camp2018In: Frontiers in Immunology, ISSN 1664-3224, E-ISSN 1664-3224, Vol. 9, article id 1939Article in journal (Refereed)
    Abstract [en]

    Early clearance of tuberculosis is the successful eradication of inhaled bacteria before the development of an adaptive immune response. We previously showed, by utilizing a non-virulent mycobacteria infection model, that C57BL/6 mice are more efficient than BALB/c in their control of bacterial growth in the lungs during the first weeks of the infection. Here, we assessed early (within 1-3 days) innate immune events locally in the lungs to identify factors that may contribute to the control of non-virulent mycobacterial burden. We confirmed that C57BL/6 mice are more resistant to infection compared with BALB/c after intranasal inoculation with mycobacterium. Transcriptomic analyses revealed a remarkably silent signature in C57BL/6 mice despite effective control of bacterial growth. In contrast, BALB/c mice up-regulated genes associated with neutrophil and myeloid cell chemotaxis and migration. Flow cytometry analyses corroborated the transcriptomic analyses and demonstrated influx of both neutrophil and myeloid cell populations in BALB/c mice, while these did not increase in C57BL/6 mice. We further detected increased release of TNF-alpha from BALB/c lung cells but limited release from C57BL/6-derived cells. However, C57BL/6 mice showed a marked early up-regulation of the Camp gene, encoding the cathelicidin CRAMP peptide, post-mycobacterial exposure. CRAMP (LL-37 in human) expression in the lungs was confirmed using immunofluorescence staining. Altogether, these findings show that C57BL/6 mice can clear the mycobacterial infection early and that this early control is associated with high CRAMP expression in the lungs without concomitant influx of immune cells. The role of CRAMP/LL-37 during mycobacterial infection may be relevant for novel protective strategies, and warrants further studies of human cohorts.

  • 11. Ainsbury, Elizabeth A.
    et al.
    Al-hafidh, Jenna
    Bajinskis, Ainars
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Barnard, Stephen
    Barquinero, Joan Francesc
    Beinke, Christina
    de Gelder, Virginie
    Gregoire, Eric
    Jaworska, Alicja
    Lindholm, Carita
    Lloyd, David
    Moquet, Jayne
    Nylund, Reetta
    Oestreicher, Ursula
    Roch-Lefevre, Sandrine
    Rothkamm, Kai
    Romm, Horst
    Scherthan, Harry
    Sommer, Sylwester
    Thierens, Hubert
    Vandevoorde, Charlot
    Vral, Anne
    Wojcik, Andrzej
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Inter- and intra-laboratory comparison of a multibiodosimetric approach to triage in a simulated, large scale radiation emergency2014In: International Journal of Radiation Biology, ISSN 0955-3002, E-ISSN 1362-3095, Vol. 90, no 2, p. 193-202Article in journal (Refereed)
    Abstract [en]

    Purpose: The European Union's Seventh Framework Programme-funded project 'Multi-disciplinary biodosimetric tools to manage high scale radiological casualties' (MULTIBIODOSE) has developed a multiparametric approach to radiation biodosimetry, with a particular emphasis on triage of large numbers of potentially exposed individuals following accidental exposures. In November 2012, an emergency exercise took place which tested the capabilities of the MULTIBIODOSE project partners. The exercise described here had a dual purpose: Intercomparison of (i) three biodosimetric assays, and (ii) the capabilities of the seven laboratories, with regards to provision of triage status for suspected radiation exposed individuals. Materials and methods: Three biological dosimetry tools - the dicentric, micronucleus and gamma-H2AX (the phosphorylated form of member X of histone H2A, in response to DNA double-strand breaks) foci assays - were tested, in addition to provision of the triage status results (low exposure: <1 Gy; medium exposure: 1-2 Gy; high exposure: >2 Gy) by the MULTIBIODOSE software. The exercise was run in two modes: An initial triage categorisation of samples (based on the first dose estimates for each assay received from each laboratory) followed by collation of the full set of estimated doses (all the results from all modes of each assay carried out by the participating laboratories) calculated using as many modes of operation as possible of the different assays developed during the project. Simulated acute whole body and partial body exposures were included. Results: The results of the initial triage categorisation and the full comparison of assays and methods within and between laboratories are presented here. Conclusions: The data demonstrate that the MULTIBIODOSE approach of applying multiparametric tools to radiation emergencies is valid and effective.

  • 12. Ainsbury, Elizabeth A.
    et al.
    Barnard, Stephen
    Barrios, Lleonard
    Fattibene, Paola
    de Gelder, Virginie
    Gregoire, Eric
    Lindholm, Carita
    Lloyd, David
    Nergaard, Inger
    Rothkamm, Kai
    Romm, Horst
    Scherthan, Harry
    Thierens, Hubert
    Vandevoorde, Charlot
    Woda, Clemens
    Wojcik, Andrzej
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    MULTIBIODOSE RADIATION EMERGENCY TRIAGE CATEGORIZATION SOFTWARE2014In: Health Physics, ISSN 0017-9078, E-ISSN 1538-5159, Vol. 107, no 1, p. 83-89Article in journal (Refereed)
    Abstract [en]

    In this note, the authors describe the MULTIBIODOSE software, which has been created as part of the MULTIBIODOSE project. The software enables doses estimated by networks of laboratories, using up to five retrospective (biological and physical) assays, to be combined to give a single estimate of triage category for each individual potentially exposed to ionizing radiation in a large scale radiation accident or incident. The MULTIBIODOSE software has been created in Java. The usage of the software is based on the MULTIBIODOSE Guidance: the program creates a link to a single SQLite database for each incident, and the database is administered by the lead laboratory. The software has been tested with Java runtime environment 6 and 7 on a number of different Windows, Mac, and Linux systems, using data from a recent intercomparison exercise. The Java program MULTIBIODOSE_1.0.jar is freely available to download from http://www.multibiodose.eu/software or by contacting the software administrator: MULTIBIODOSE-software@gmx.com.

  • 13. Ainsbury, Elizabeth A.
    et al.
    Higueras, Manuel
    Puig, Pedro
    Einbeck, Jochen
    Samaga, Daniel
    Francesc Barquinero, Joan
    Barrios, Lleonard
    Brzozowska, Beata
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute. University of Warsaw, Poland.
    Fattibene, Paola
    Gregoire, Eric
    Jaworska, Alicja
    Lloyd, David
    Oestreicher, Ursula
    Romm, Horst
    Rothkamm, Kai
    Roy, Laurence
    Sommer, Sylwester
    Terzoudi, Georgia
    Thierens, Hubert
    Trompier, Francois
    Vral, Anne
    Woda, Clemens
    Uncertainty of fast biological radiation dose assessment for emergency response scenarios2017In: International Journal of Radiation Biology, ISSN 0955-3002, E-ISSN 1362-3095, Vol. 93, no 1, p. 127-135Article in journal (Refereed)
    Abstract [en]

    Purpose: Reliable dose estimation is an important factor in appropriate dosimetric triage categorization of exposed individuals to support radiation emergency response. Materials and methods: Following work done under the EU FP7 MULTIBIODOSE and RENEB projects, formal methods for defining uncertainties on biological dose estimates are compared using simulated and real data from recent exercises. Results: The results demonstrate that a Bayesian method of uncertainty assessment is the most appropriate, even in the absence of detailed prior information. The relative accuracy and relevance of techniques for calculating uncertainty and combining assay results to produce single dose and uncertainty estimates is further discussed. Conclusions: Finally, it is demonstrated that whatever uncertainty estimation method is employed, ignoring the uncertainty on fast dose assessments can have an important impact on rapid biodosimetric categorization.

  • 14. Ainsbury, Elizabeth
    et al.
    Badie, Christophe
    Barnard, Stephen
    Manning, Grainne
    Moquet, Jayne
    Abend, Michael
    Antunes, Ana Catarina
    Barrios, Lleonard
    Bassinet, Celine
    Beinke, Christina
    Bortolin, Emanuela
    Bossin, Lily
    Bricknell, Clare
    Brzoska, Kamil
    Buraczewska, Iwona
    Huertas Castano, Carlos
    Cemusova, Zina
    Christiansson, Maria
    Mateos Cordero, Santiago
    Coster, Guillaume
    Della Monac, Sara
    Desangles, Francois
    Discher, Michael
    Dominguez, Inmaculada
    Doucha-Senf, Sven
    Eakins, Jon
    Fattibene, Paola
    Filippi, Silvia
    Frenzel, Monika
    Georgieva, Dimka
    Gregoire, Eric
    Guogyte, Kamile
    Hadjidekova, Valeria
    Hadjiiska, Ljubomira
    Hristova, Rositsa
    Karakosta, Maria
    Kis, Eniko
    Kriehuber, Ralf
    Lee, Jungil
    Lloyd, David
    Lumniczky, Katalin
    Lyng, Fiona
    Macaeva, Ellina
    Majewski, Matthaeus
    Vanda Martins, S.
    McKeever, Stephen W. S.
    Meade, Aidan
    Medipally, Dinesh
    Meschini, Roberta
    M'kacher, Radhia
    Gil, Octavia Monteiro
    Montero, Alegria
    Moreno, Mercedes
    Noditi, Mihaela
    Oestreicher, Ursula
    Oskamp, Dominik
    Palitti, Fabrizio
    Palma, Valentina
    Pantelias, Gabriel
    Pateux, Jerome
    Patrono, Clarice
    Pepe, Gaetano
    Port, Matthias
    Jesus Prieto, Maria
    Quattrini, Maria Cristina
    Quintens, Roel
    Ricoul, Michelle
    Roy, Laurence
    Sabatier, Laure
    Sebastia, Natividad
    Sholom, Sergey
    Sommer, Sylwester
    Staynova, Albena
    Strunz, Sonja
    Terzoudi, Georgia
    Testa, Antonella
    Trompier, Francois
    Valente, Marco
    Van Hoey, Olivier
    Veronese, Ivan
    Wojcik, Andrzej
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Woda, Clemens
    Integration of new biological and physical retrospective dosimetry methods into EU emergency response plans - joint RENEB and EURADOS inter-laboratory comparisons2017In: International Journal of Radiation Biology, ISSN 0955-3002, E-ISSN 1362-3095, Vol. 93, no 1, p. 99-109Article in journal (Refereed)
    Abstract [en]

    Purpose: RENEB, 'Realising the European Network of Biodosimetry and Physical Retrospective Dosimetry,' is a network for research and emergency response mutual assistance in biodosimetry within the EU. Within this extremely active network, a number of new dosimetry methods have recently been proposed or developed. There is a requirement to test and/or validate these candidate techniques and inter-comparison exercises are a well-established method for such validation. Materials and methods: The authors present details of inter-comparisons of four such new methods: dicentric chromosome analysis including telomere and centromere staining; the gene expression assay carried out in whole blood; Raman spectroscopy on blood lymphocytes, and detection of radiation induced thermoluminescent signals in glass screens taken from mobile phones. Results: In general the results show good agreement between the laboratories and methods within the expected levels of uncertainty, and thus demonstrate that there is a lot of potential for each of the candidate techniques. Conclusions: Further work is required before the new methods can be included within the suite of reliable dosimetry methods for use by RENEB partners and others in routine and emergency response scenarios.

  • 15. Alkadarou, Tayseer
    et al.
    Musa, Ahmed
    Alkadarou, Abedelgader
    Mahfouz, Mohamed S
    Troye-Blomberg, Marita
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Elhassan, Ahmed M
    Elhassan, Ibrahim M
    Immunological characteristics of hyperreactive malarial splenomegaly syndrome in sudanese patients2013In: Journal of Tropical Medicine, ISSN 1687-9686, E-ISSN 1687-9694, Vol. 2013, p. 961051-Article in journal (Refereed)
    Abstract [en]

    Hyperreactive Malarial Splenomegaly (HMS) is defined as a massive enlargement of the spleen resulting from abnormal immune responses after repeated exposure to the malaria parasites. This study was carried out in Khartoum, Sudan. Sudan is considered to be one of the countries where HMS is quite prevalent. The objective of the study was to determine the incidence of HMS in patients who reported to the Omdurman Tropical Diseases Hospital (OMTDH) in Sudan and to investigate the basic laboratory and immunological characteristics of this condition in these patients. A cross-sectional study was carried out in OMTDH, and all patients with enlarged spleens were included in the study. Thirty-one out of 335 (9.3%) patients were diagnosed as having the HMS condition using international criteria for HMS diagnosis. The mean serum immunoglobulin M (IgM) levels in HMS patient groups were 14.3 ± 5 g/L, and this was significantly higher compared with geographically matched controls (P < 0.001). Immunoglobulin G (IgG) C anticircumsporozoite (CSP) antibody levels were higher in the HMS patients although the difference was not statistically significant, when compared with a group of patients with mild malaria. In comparison with naïve European controls, both the HMS and the mild malaria groups had significantly higher antimalarial antibody levels P < 0.001 and P < 0.01, respectively. Plasma levels of interleukin 10 (IL10) and interferon gamma (IFN γ ) were significantly increased in the HMS patients compared with the healthy control donors (P < 0.05 and P < 0.01) for IL10 and IFN γ , respectively. The findings of this study suggest that HMS is one of the significant causes of tropical splenomegaly in Sudan. HMS is associated with significant elevations of circulating IgM and antimalarial IgG antibodies as well as IL10 and IFN γ .

  • 16. Almuzzaini, Bader
    et al.
    Sarshad, Aishe A.
    Rahmanto, Aldwin S.
    Hansson, Magnus L.
    Von Euler, Anne
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Sangfelt, Olle
    Visa, Neus
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Östlund Farrants, Ann-Kristin
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Percipalle, Piergiorgio
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    In beta-actin knockouts, epigenetic reprogramming and rDNA transcription inactivation lead to growth and proliferation defects2016In: The FASEB Journal, ISSN 0892-6638, E-ISSN 1530-6860, Vol. 30, no 8, p. 2860-2873Article in journal (Refereed)
    Abstract [en]

    Actin and nuclear myosin 1 (NM1) are regulators of transcription and chromatin organization. Using a genome-wide approach, we report here that beta-actin binds intergenic and genic regions across the mammalian genome, associated with both protein-coding and rRNA genes. Within the rDNA, the distribution of beta-actin correlated with NM1 and the other subunits of the B-WICH complex, WSTF and SNF2h. In beta-actin(-/-) mouse embryonic fibroblasts (MEFs), we found that rRNA synthesis levels decreased concomitantly with drops in RNA polymerase I (Pol I) and NM1 occupancies across the rRNA gene. Reintroduction of wild-type beta-actin, in contrast to mutated forms with polymerization defects, efficiently rescued rRNA synthesis underscoring the direct role for a polymerization-competent form of beta-actin in Pol I transcription. The rRNA synthesis defects in the beta-actin(-/-) MEFs are a consequence of epigenetic reprogramming with up-regulation of the repressive mark H3K4me1 (mono-methylation of lys4 on histone H3) and enhanced chromatin compaction at promoter-proximal enhancer (T0 sequence), which disturb binding of the transcription factor TTF1. We propose a novel genome-wide mechanism where the polymerase-associated beta-actin synergizes with NM1 to coordinate permissive chromatin with Pol I transcription, cell growth, and proliferation.

  • 17. Almuzzaini, Bader
    et al.
    Sarshad, Aishe A.
    Östlund Farrants, Ann-Kristin
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Percipalle, Piergiorgio
    Nuclear myosin 1 contributes to a chromatin landscape compatible with RNA polymerase II transcription activation2015In: BMC Biology, ISSN 1741-7007, E-ISSN 1741-7007, Vol. 13, article id 35Article in journal (Refereed)
    Abstract [en]

    Background: Nuclear myosin 1c (NM1) is emerging as a regulator of transcription and chromatin organization. Results: Using chromatin immunoprecipitation and deep sequencing (ChIP-Seq) in combination with molecular analyses, we investigated the global association of NM1 with the mammalian genome. Analysis of the ChIP-Seq data demonstrates that NM1 binds across the entire mammalian genome with occupancy peaks correlating with distributions of RNA Polymerase II (Pol II) and active epigenetic marks at class II gene promoters. In mouse embryonic fibroblasts subjected to RNAi mediated NM1 gene silencing, we show that NM1 synergizes with polymerase-associated actin to maintain active Pol II at the promoter. NM1 also co-localizes with the nucleosome remodeler SNF2h at class II promoters where they assemble together with WSTF as part of the B-WICH complex. A high resolution micrococcal nuclease (MNase) assay and quantitative real time PCR shows that this mechanism is required for local chromatin remodeling. Following B-WICH assembly, NM1 mediates physical recruitment of the histone acetyl transferase PCAF and the histone methyl transferase Set1/Ash2 to maintain and preserve H3K9acetylation and H3K4trimethylation for active transcription. Conclusions: We propose a novel genome-wide mechanism where myosin synergizes with Pol II-associated actin to link the polymerase machinery with permissive chromatin for transcription activation.

  • 18. Alvarez-Crespo, Mayte
    et al.
    Csikasz, Robert I.
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Martinez-Sanchez, Noelia
    Dieguez, Carlos
    Cannon, Barbara
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Nedergaard, Jan
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Lopez, Miguel
    Essential role of UCP1 modulating the central effects of thyroid hormones on energy balance2016In: Molecular metabolism, ISSN 2212-8778, Vol. 5, no 4, p. 271-282Article in journal (Refereed)
    Abstract [en]

    Objective: Classically, metabolic effects of thyroid hormones (THs) have been considered to be peripherally mediated, i.e. different tissues in the body respond directly to thyroid hormones with an increased metabolism. An alternative view is that the metabolic effects are centrally regulated. We have examined here the degree to which prolonged, centrally infused triiodothyronine (T3) could in itself induce total body metabolic effects and the degree to which brown adipose tissue (BAT) thermogenesis was essential for such effects, by examining uncoupling protein 1 (UCP1) KO mice. Methods: Wildtype and UPC1 KO mice were centrally-treated with T3 by using minipumps. Metabolic measurements were analyzed by indirect calorimetry and expression analysis by RT-PCR or western blot. BAT morphology and histology were studied by immunohistochemistry. Results: We found that central T3-treatment led to reduced levels of hypothalamic AMP-activated protein kinase (AMPK) and elevated body temperature (0.7 degrees C). UCP1 was essential for the T3-induced increased rate of energy expenditure, which was only observable at thermoneutrality and notably only during the active phase, for the increased body weight loss, for the increased hypothalamic levels of neuropeptide Y (NPY) and agouti-related peptide (AgRP) and for the increased food intake induced by central T3-treatment. Prolonged central T3-treatment also led to recruitment of BAT and britening/beiging (browning) of inguinal white adipose tissue (iWAT). Conclusions: We conclude that UCP1 is essential for mediation of the central effects of thyroid hormones on energy balance, and we suggest that similar UCP1-dependent effects may underlie central energy balance effects of other agents.

  • 19. Amoako-Sakyi, Daniel
    et al.
    Adukpo, Selorme
    Kusi, Kwadwo A.
    Dodoo, Daniel
    Ofori, Michael F.
    Adjei, George O.
    Edoh, Dominic E.
    Asmah, Richard H.
    Brown, Charles
    Adu, Bright
    Obiri-Yeboah, Dorcas
    Futagbi, Godfred
    Abubakari, Sharif Buari
    Troye-Blomberg, Marita
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Akanmori, Bartholomew D.
    Goka, Bamenla Q.
    Arko-Mensah, John
    Gyan, Ben A.
    A STAT6 Intronic Single-Nucleotide Polymorphism is Associated with Clinical Malaria in Ghanaian Children2016In: Genetics and Epigenetics, ISSN 1179-237X, Vol. 8, p. 7-14Article in journal (Refereed)
    Abstract [en]

    Malaria pathogenesis may be influenced by IgE responses and cytokine cross-regulation. Several mutations in the IL-4/STAT6 signaling pathway can alter cytokine cross-regulation and IgE responses during a Plasmodium falciparum malarial infection. This study investigated the relationship between a STAT6 intronic single-nucleotide polymorphism (rs3024974), total IgE, cytokines, and malaria severity in 238 Ghanaian children aged between 0.5 and 13 years. Total IgE and cytokine levels were measured by ELISA, while genotyping was done by polymerase chain reaction-restriction fragment length polymorphism (RFLP). Compared with healthy controls, heterozygosity protected against clinical malaria: uncomplicated malaria (odds ratios [OR] = 0.13, P < 0.001), severe malarial anemia (OR = 0.18, P, 0.001), and cerebral malaria (OR = 0.39, P = 0.022). Levels of total IgE significantly differed among malaria phenotypes (P = 0.044) and rs3024974 genotypes (P = 0.037). Neither cytokine levels nor IL-6/IL-10 ratios were associated with malaria phenotypes or rs3024974 genotypes. This study suggests a role for rs3024974 in malaria pathogenesis and offers further insights into an IL-4/STAT6 pathway mutation in malaria pathogenesis.

  • 20. Anantharaman, Aparna
    et al.
    Tripathi, Vidisha
    Khan, Abid
    Yoon, Je-Hyun
    Singh, Deepak K.
    Gholamalamdari, Omid
    Guang, Shuomeng
    Ohlson, Johan
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Wahlstedt, Helene
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Öhman, Marie
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Jantsch, Michael F.
    Conrad, Nicholas K.
    Ma, Jian
    Gorospe, Myriam
    Prasanth, Supriya G.
    Prasanth, Kannanganattu V.
    ADAR2 regulates RNA stability by modifying access of decay-promoting RNA-binding proteins2017In: Nucleic Acids Research, ISSN 0305-1048, E-ISSN 1362-4962, Vol. 45, no 7, p. 4189-4201Article in journal (Refereed)
    Abstract [en]

    Adenosine deaminases acting on RNA (ADARs) catalyze the editing of adenosine residues to inosine (A-to-I) within RNA sequences, mostly in the introns and UTRs (un-translated regions). The significance of editing within non-coding regions of RNA is poorly understood. Here, we demonstrate that association of ADAR2 with RNA stabilizes a subset of transcripts. ADAR2 interacts with and edits the 3' UTR of nuclear-retained Cat2 transcribed nuclear RNA (Ctn RNA). In absence of ADAR2, the abundance and half-life of Ctn RNA are significantly reduced. Furthermore, ADAR2-mediated stabilization of Ctn RNA occurred in an editing-independent manner. Unedited Ctn RNA shows enhanced interaction with the RNA-binding proteins HuR and PARN [Poly(A) specific ribonuclease deadenylase]. HuR and PARN destabilize Ctn RNA in absence of ADAR2, indicating that ADAR2 stabilizes Ctn RNA by antagonizing its degradation by PARN and HuR. Transcriptomic analysis identified other RNAs that are regulated by a similar mechanism. In summary, we identify a regulatory mechanism whereby ADAR2 enhances target RNA stability by limiting the interaction of RNA-destabilizing proteins with their cognate substrates.

  • 21. Anchang-Kimbi, Judith K.
    et al.
    Achidi, Eric A.
    Apinjoh, Tobias O.
    Mugri, Regina N.
    Chi, Hanesh Fru
    Tata, Rolland B.
    Nkegoum, Blaise
    Mendimi, Joseph-Marie N.
    Sverremark-Ekström, Eva
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Troye Blomberg, Marita
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Antenatal care visit attendance, intermittent preventive treatment during pregnancy (IPTp) and malaria parasitaemia at delivery2014In: Malaria Journal, ISSN 1475-2875, E-ISSN 1475-2875, Vol. 13, p. 162-Article in journal (Refereed)
    Abstract [en]

    Background: The determinants and barriers for delivery and uptake of IPTp vary with different regions in sub-Saharan Africa. This study evaluated the determinants of ANC clinic attendance and IPTp-SP uptake among parturient women from Mount Cameroon Area and hypothesized that time of first ANC clinic attendance could influence uptake of IPTp-SP/dosage and consequently malaria parasite infection status at delivery. Methods: Two cross sectional surveys were carried out at the Government Medical Centre in the Mutengene Health Area, Mt Cameroon Area from March to October 2007 and June 2008 to April 2009. Consented parturient women were consecutively enrolled in both surveys. In 2007, socio-demographic data, ANC clinic attendance, gestational age, fever history and reported use/dosage of IPTp-SP were documented using a structured questionnaire. In the second survey only IPT-SP usage/dosage was recorded. Malaria parasitaemia at delivery was determined by blood smear microscopy and placental histology. Results and discussion: In 2007, among the 287 women interviewed, 2.2%, 59.7%, and 38.1% enrolled in the first, second and third trimester respectively. About 90% of women received at least one dose SP but only 53% received the two doses in 2007 and by 2009 IPTp-two doses coverage increased to 64%. Early clinic attendance was associated (P = 0.016) with fever history while being unmarried (OR = 2.2; 95% CI: 1.3-3.8) was significantly associated with fewer clinic visits (<4visits). Women who received one SP dose (OR = 3.7; 95% CI: 2.0-6.8) were more likely not to have attended >= 4visits. A higher proportion (P < 0.001) of women with first visit during the third trimester received only one dose, meanwhile, those who had an early first ANC attendance were more likely (OR = 0.4; 95% CI = 0.2 - 0.7) to receive two or more doses. Microscopic parasitaemia at delivery was frequent (P = 0.007) among women who enrolled in the third trimester and had received only one SP dose than in those with two doses. Conclusion: In the study area, late first ANC clinic enrolment and fewer clinic visits may prevent the uptake of two SP doses and education on early and regular ANC clinic visits can increase IPTp coverage.

  • 22. Anchang-Kimbi, Judith K.
    et al.
    Achidi, Eric Akum
    Nkegoum, Blaise
    Mendimi, Joseph-Marie N.
    Sverremark-Ekström, Eva
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Troye-Blomberg, Marita
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    IgG isotypic antibodies to crude Plasmodium falciparum blood-stage antigen associated with placental malaria infection in parturient Cameroonian women2016In: African Health Sciences, ISSN 1680-6905, E-ISSN 1729-0503, Vol. 16, no 4, p. 1007-1017Article in journal (Refereed)
    Abstract [en]

    Background: Few studies have reported an association between placental malaria (PM) infection and levels of isotypic antibodies against non-pregnancy associated antigens. Objective: To determine and evaluate IgG isotypic antibody levels to crude P. falciparum blood stage in women with and without PM infection. Methods: Levels of IgG (IgG1-IgG4) and IgM to crude P. falciparum blood stage antigen were measured by ELISA in 271 parturient women. Placental malaria infection was determined by placental blood microscopy and placental histology. Age, parity and intermittent preventive treatment during pregnancy with sulphadoxine-pyrimethamine (IPTp-SP) usage were considered during analysis. Results: P. falciparum-specific IgG1 (96.5%) and IgG3 (96.7%) antibodies were predominant compared with IgG2 (64.6%) and IgG4 (49.1%). Active PM infection was associated with significant increased levels of IgG1, IgG4 and IgM while lower levels of these antibodies were associated with uptake of two or more IPTp-SP doses. PM infection was the only independent factor associated with IgG4 levels. Mean IgG1 + IgG3/IgG2 + IgG4 and IgG1 + IgG2 + IgG3/IgG4 ratios were higher among the PM-uninfected group while IgG4/IgG2 ratio prevailed in the infected group. Conclusion: PM infection and IPTp-SP dosage influenced P. falciparum-specific isotypic antibody responses to blood stage antigens. An increase in IgG4 levels in response to PM infection is of particular interest.

  • 23.
    Andreasson, Claes
    et al.
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Schick, Anna J.
    Pfeiffer, Susanne M.
    Sarov, Mihail
    Stewart, Francis
    Wurst, Wolfgang
    Schick, Joel A.
    Direct Cloning of Isogenic Murine DNA in Yeast and Relevance of Isogenicity for Targeting in Embryonic Stem Cells2013In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 8, no 9, p. e74207-Article in journal (Refereed)
    Abstract [en]

    Efficient gene targeting in embryonic stem cells requires that modifying DNA sequences are identical to those in the targeted chromosomal locus. Yet, there is a paucity of isogenic genomic clones for human cell lines and PCR amplification cannot be used in many mutation-sensitive applications. Here, we describe a novel method for the direct cloning of genomic DNA into a targeting vector, pRTVIR, using oligonucleotide-directed homologous recombination in yeast. We demonstrate the applicability of the method by constructing functional targeting vectors for mammalian genes Uhrf1 and Gfap. Whereas the isogenic targeting of the gene Uhrf1 showed a substantial increase in targeting efficiency compared to non-isogenic DNA in mouse E14 cells, E14-derived DNA performed better than the isogenic DNA in JM8 cells for both Uhrf1 and Gfap. Analysis of 70 C57BL/6-derived targeting vectors electroporated in JM8 and E14 cell lines in parallel showed a clear dependence on isogenicity for targeting, but for three genes isogenic DNA was found to be inhibitory. In summary, this study provides a straightforward methodological approach for the direct generation of isogenic gene targeting vectors.

  • 24.
    Ankarklev, Johan
    et al.
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Lebbad, Marianne
    Einarsson, Elin
    Franzen, Oscar
    Ahola, Harri
    Troell, Karin
    Svard, Staffan G.
    A novel high-resolution multilocus sequence typing of Giardia intestinalis Assemblage A isolates reveals zoonotic transmission, clonal outbreaks and recombination2018In: Infection, Genetics and Evolution, ISSN 1567-1348, E-ISSN 1567-7257, Vol. 60, p. 7-16Article in journal (Refereed)
    Abstract [en]

    Molecular epidemiology and genotyping studies of the parasitic protozoan Giardia intestinalis have proven difficult due to multiple factors, such as low discriminatory power in the commonly used genotyping loci, which has hampered molecular analyses of outbreak sources, zoonotic transmission and virulence types. Here we have focused on assemblage A Giardia and developed a high-resolution assemblage-specific multilocus sequence typing (MLST) method. Analyses of sequenced G. intestinalis assemblage A genomes from different sub-assemblages identified a set of six genetic loci with high genetic variability. DNA samples from both humans (n = 44) and animals (n = 18) that harbored Giardia assemblage A infections, were PCR amplified (557-700 bp products) and sequenced at the six novel genetic loci. Bioinformatic analyses showed five to ten-fold higher levels of polymorphic sites than what was previously found among assemblage A samples using the classic genotyping loci. Phylogenetically, a division of two major clusters in assemblage A became apparent, separating samples of human and animal origin. A subset of human samples (n = 9) from a documented Giardia outbreak in a Swedish day-care center, showed full complementarity at nine genetic loci (the six new and the standard BG, TPI and GDH loci), strongly suggesting one source of infection. Furthermore, three samples of human origin displayed MLST profiles that were phylogenetically more closely related to MLST profiles from animal derived samples, suggesting zoonotic transmission. These new genotyping loci enabled us to detect events of recombination between different assemblage A isolates but also between assemblage A and E isolates. In summary, we present a novel and expanded MLST strategy with significantly improved sensitivity for molecular analyses of virulence types, zoonotic potential and source tracking for assemblage A Giardia.

  • 25. Arama, Charles
    et al.
    Maiga, Bakary
    Dolo, Amagana
    Kouriba, Bourema
    Traore, Boubacar
    Crompton, Peter D.
    Pierce, Susan K.
    Troye-Blomberg, Marita
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Miller, Louis H.
    Doumbo, Ogobara K.
    Ethnic differences in susceptibility to malaria: What have we learned from immuno-epidemiological studies in West Africa?2015In: Acta Tropica, ISSN 0001-706X, E-ISSN 1873-6254, Vol. 146, p. 152-156Article, review/survey (Refereed)
    Abstract [en]

    There are many fundamental aspects of the immunobiology of Plasmodium falciparum infections that are not fully understood, therefore limiting our comprehension of how people become immune to malaria and why some ethnic groups living in malaria endemic areas are less susceptible than others. The complexity of parasite-host interactions and the genetic diversity of the parasites as well as the human host complicate our strategy to address this issue. In this mini-review we discuss and summarize what we have learned about African ethnic differences in susceptibility to malaria from immuno-epidemiological studies. Additionally, we suggest research topics that might be of great value for dissecting the mechanisms of protection by providing new insights into molecular interactions between the parasite and the host.

  • 26. Arama, Charles
    et al.
    Quin, Jaclyn E.
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Kouriba, Bourema
    Östlund Farrants, Ann-Kristin
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Troye-Blomberg, Marita
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Doumbo, Ogobara K.
    Epigenetics and Malaria Susceptibility/Protection: A Missing Piece of the Puzzle2018In: Frontiers in Immunology, ISSN 1664-3224, E-ISSN 1664-3224, Vol. 9, article id 1733Article, review/survey (Refereed)
    Abstract [en]

    A better understanding of stable changes in regulation of gene expression that result from epigenetic events is of great relevance in the development of strategies to prevent and treat infectious diseases. Histone modification and DNA methylation are key epigenetic mechanisms that can be regarded as marks, which ensure an accurate transmission of the chromatin states and gene expression profiles over generations of cells. There is an increasing list of these modifications, and the complexity of their action is just beginning to be understood. It is clear that the epigenetic landscape plays a fundamental role in most biological processes that involve the manipulation and expression of DNA. Although the molecular mechanism of gene regulation is relatively well understood, the hierarchical order of events and dependencies that lead to protection against infection remain largely unknown. In this review, we propose that host epigenetics is an essential, though relatively under studied, factor in the protection or susceptibility to malaria.

  • 27.
    Arama, Charles
    et al.
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute. University of Sciences Techniques and Technologies of Bamako, Mali.
    Troye-Blomberg, Marita
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    The path of malaria vaccine development: challenges and perspectives2014In: Journal of Internal Medicine, ISSN 0954-6820, E-ISSN 1365-2796, Vol. 275, no 5, p. 456-466Article, review/survey (Refereed)
    Abstract [en]

    Malaria is a life-threatening disease caused by parasites of the Plasmodium genus. In many parts of the world, the parasites have developed resistance to a number of antimalarial agents. Key interventions to control malaria include prompt and effective treatment with artemisinin-based combination therapies, use of insecticidal nets by individuals at risk and active research into malaria vaccines. Protection against malaria through vaccination was demonstrated more than 30years ago when individuals were vaccinated via repeated bites by Plasmodium falciparum-infected and irradiated but still metabolically active mosquitoes. However, vaccination with high doses of irradiated sporozoites injected into humans has long been considered impractical. Yet, following recent success using whole-organism vaccines, the approach has received renewed interest; it was recently reported that repeated injections of irradiated sporozoites increased protection in 80 vaccinated individuals. Other approaches include subunit malaria vaccines, such as the current leading candidate RTS,S (consisting of fusion between a portion of the P.falciparum-derived circumsporozoite protein and the hepatitis B surface antigen), which has been demonstrated to induce reasonably good protection. Although results have been encouraging, the level of protection is generally considered to be too low to achieve eradication of malaria. There is great interest in developing new and better formulations and stable delivery systems to improve immunogenicity. In this review, we will discuss recent strategies to develop efficient malaria vaccines.

  • 28.
    Arefin, Badrul
    et al.
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Kucerova, Lucie
    Dobes, Pavel
    Márkus, Róbert
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Strnad, Hynek
    Wang, Zhi
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Hyrsl, Pavel
    Zurovec, Michal
    Theopold, Ulrich
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Genome-Wide Transcriptional Analysis of Drosophila Larvae Infected by Entomopathogenic Nematodes Shows Involvement of Complement, Recognition and Extracellular Matrix Proteins2014In: Journal of Innate Immunity, ISSN 1662-811X, E-ISSN 1662-8128, Vol. 6, no 2, p. 192-204Article in journal (Refereed)
    Abstract [en]

    Heterorhabditis bacteriophora is an entomopathogenic nematode (EPN) which infects its host by accessing the hemolymph where it releases endosymbiotic bacteria of the species Photorhabdus luminescens. We performed a genome-wide transcriptional analysis of the Drosophila response to EPN infection at the time point at which the nematodes reached the hemolymph either via the cuticle or the gut and the bacteria had started to multiply. Many of the most strongly induced genes have been implicated in immune responses in other infection models. Mapping of the complete set of differentially regulated genes showed the hallmarks of a wound response, but also identified a large fraction of EPN-specific transcripts. Several genes identified by transcriptome profiling or their homologues play protective roles during nematode infections. Genes that positively contribute to controlling nematobacterial infections encode: a homolog of thioester-containing complement protein 3, a basement membrane component (glutactin), a recognition protein (GNBP-like 3) and possibly several small peptides. Of note is that several of these genes have not previously been implicated in immune responses.

  • 29.
    Arefin, Badrul
    et al.
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Kucerova, Lucie
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Krautz, Robert
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Kranenburg, Holger
    Parvin, Farjana
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Theopold, Ulrich
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Apoptosis in Hemocytes Induces a Shift in Effector Mechanisms in the Drosophila Immune System and Leads to a Pro-Inflammatory State2015In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 10, no 8, article id e0136593Article in journal (Refereed)
    Abstract [en]

    Apart from their role in cellular immunity via phagocytosis and encapsulation, Drosophila hemocytes release soluble factors such as antimicrobial peptides, and cytokines to induce humoral responses. In addition, they participate in coagulation and wounding, and in development. To assess their role during infection with entomopathogenic nematodes, we depleted plasmatocytes and crystal cells, the two classes of hemocytes present in naive larvae by expressing proapoptotic proteins in order to produce hemocyte-free (Hml-apo, originally called Hemo(less)) larvae. Surprisingly, we found that Hml-apo larvae are still resistant to nematode infections. When further elucidating the immune status of Hml-apo larvae, we observe a shift in immune effector pathways including massive lamellocyte differentiation and induction of Toll-as well as repression of imd signaling. This leads to a pro-inflammatory state, characterized by the appearance of melanotic nodules in the hemolymph and to strong developmental defects including pupal lethality and leg defects in escapers. Further analysis suggests that most of the phenotypes we observe in Hml-apo larvae are alleviated by administration of antibiotics and by changing the food source indicating that they are mediated through the microbiota. Biochemical evidence identifies nitric oxide as a key phylogenetically conserved regulator in this process. Finally we show that the nitric oxide donor L-arginine similarly modifies the response against an early stage of tumor development in fly larvae.

  • 30.
    Arefin, Badrul
    et al.
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Kunc, Martin
    Krautz, Robert
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Theopold, Ulrich
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Drosophila models for different grades of leukemia2016Manuscript (preprint) (Other academic)
  • 31.
    Arefin, Badrul
    et al.
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Kunc, Martin
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute. Institute of Experimental Biology, Czech Republic.
    Krautz, Robert
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Theopold, Ulrich
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    The Immune Phenotype of Three Drosophila Leukemia Models2017In: G3: Genes, Genomes, Genetics, ISSN 2160-1836, E-ISSN 2160-1836, Vol. 7, no 7, p. 2139-2149Article in journal (Refereed)
    Abstract [en]

    Many leukemia patients suffer from dysregulation of their immune system, making them more susceptible to infections and leading to general weakening (cachexia). Both adaptive and innate immunity are affected. The fruit fly Drosophila melanogaster has an innate immune system, including cells of the myeloid lineage (hemocytes). To study Drosophila immunity and physiology during leukemia, we established three models by driving expression of a dominant-active version of the Ras oncogene (Ras(V12)) alone or combined with knockdowns of tumor suppressors in Drosophila hemocytes. Our results show that phagocytosis, hemocyte migration to wound sites, wound sealing, and survival upon bacterial infection of leukemic lines are similar to wild type. We find that in all leukemic models the two major immune pathways (Toll and Imd) are dysregulated. Toll-dependent signaling is activated to comparable extents as after wounding wild-type larvae, leading to a proinflammatory status. In contrast, Imd signaling is suppressed. Finally, we notice that adult tissue formation is blocked and degradation of cell masses during metamorphosis of leukemic lines, which is akin to the state of cancer-dependent cachexia. To further analyze the immune competence of leukemic lines, we used a natural infection model that involves insect-pathogenic nematodes. We identified two leukemic lines that were sensitive to nematode infections. Further characterization demonstrates that despite the absence of behavioral abnormalities at the larval stage, leukemic larvae show reduced locomotion in the presence of nematodes. Taken together, this work establishes new Drosophila models to study the physiological, immunological, and behavioral consequences of various forms of leukemia.

  • 32.
    Arefin, Md. Badrul
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute. Stockholm University.
    Molecular characterization of the Drosophila responses towards nematodes2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    A sophisticated evolutionary conserved innate immune system has evolved in insects to fight pathogens and to restrict damage in harmful (danger) situations including cancer. A significant amount of knowledge about different infection models in Drosophila has been generated in past decades, which revealed functional resemblances and implications for vertebrate systems. However, how Drosophila responds towards multicellular parasitic nematodes and in danger situations is still little understood. Therefore, the aim of the thesis was to characterize multiple aspects of the host defense in the two important contexts mentioned above.

    We analyzed the transcriptome profiles of nematode-infected Drosophila larvae with uninfected samples. For this we employed the entomopathogenic nematode Heterorhabditis bacteriophora with its symbiont Photorhabdus luminescence to infect Drosophila larvae. We found 642 genes were differentially regulated upon infection. Among them a significant portion belonged to immune categories. Further functional analysis identified a thioester containing protein TEP3, a recognition protein GNBP-like 3, the basement membrane component protein Glutactin and several other small peptides. Upon loss or reduced expression of these genes hosts showed mortality during nematode infections. This study uncovers a novel function for several of the genes in immunity.

    Furthermore, we investigated the cellular response towards nematodes. When we eliminated hemocytes genetically (referred to as hml-apo) in Drosophila, we found hml-apo larvae are resistant to nematodes. Subsequent characterization of hml-apo larvae showed massive lamellocyte differentiation (another blood cell type which is rare in naïve larvae), emergence of melanotic masses, up- and down-regulation of Toll and Imd signaling respectively suggesting a pro-inflammatory response. Moreover, a striking defective leg phenotype in adult escapers from pupal lethality was observed. We identified nitric oxide (NO) as a key regulator of these processes. We also showed that imaginal disc growth factors 3 (IDGF3): (a) protects hosts against nematodes, (b) is a clotting component and (c) negatively regulates Wnt and JAK/STAT signaling. To follow larval behavior in the presence or absence of nematodes we monitored Drosophila larval locomotion behaviors using FIMtrack (a recently devised automated method) to elucidate evasive strategies of hosts. Finally, we characterized host defenses in three Drosophila leukemia models with and without nematode infection. Taken together, these studies shed light on host responses in two crucial circumstances, nematode infections and danger situations.

  • 33. Arentsen, T.
    et al.
    Qian, Y.
    Gkotzis, Spyridon
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute. Karolinska Institutet, Sweden.
    Femenia, T.
    Wang, T.
    Udekwu, Klas
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Forssberg, H.
    Heijtz, R. Diaz
    The bacterial peptidoglycan-sensing molecule Pglyrp2 modulates brain development and behavior2017In: Molecular Psychiatry, ISSN 1359-4184, E-ISSN 1476-5578, Vol. 22, no 2, p. 257-266Article in journal (Refereed)
    Abstract [en]

    Recent studies have revealed that the gut microbiota modulates brain development and behavior, but the underlying mechanisms are still poorly understood. Here, we show that bacterial peptidoglycan (PGN) derived from the commensal gut microbiota can be translocated into the brain and sensed by specific pattern-recognition receptors (PRRs) of the innate immune system. Using expression-profiling techniques, we demonstrate that two families of PRRs that specifically detect PGN (that is, PGN-recognition proteins and NOD-like receptors), and the PGN transporter PepT1 are highly expressed in the developing brain during specific windows of postnatal development in both males and females. Moreover, we show that the expression of several PGN-sensing molecules and PepT1 in the developing striatum is sensitive to manipulations of the gut microbiota (that is, germ-free conditions and antibiotic treatment). Finally, we used the PGN-recognition protein 2 (Pglyrp2) knockout mice to examine the potential influence of PGN-sensing molecules on brain development and behavior. We demonstrate that the absence of Pglyrp2 leads to alterations in the expression of the autism risk gene c-Met, and sex-dependent changes in social behavior, similar to mice with manipulated microbiota. These findings suggest that the central activation of PRRs by microbial products could be one of the signaling pathways mediating the communication between the gut microbiota and the developing brain.

  • 34.
    Asgard, Rikard
    et al.
    Uppsala Univ, Dept Pharmaceut Biosci., Uppsala, Sweden.
    Haghdoost, Siamak
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Golkar, Siv Osterman
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Hellman, Bjorn
    Uppsala Univ, Dept Pharmaceut Biosci., Uppsala, Sweden.
    Czene, Stefan
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Evidence for different mechanisms of action behind the mutagenic effects of 4-NOPD and OPD: the role of DNA damage, oxidative stress and an imbalanced nucleotide pool2013In: Mutagenesis, ISSN 0267-8357, E-ISSN 1464-3804, Vol. 28, no 6, p. 637-644Article in journal (Refereed)
    Abstract [en]

    The mutagenicity of 4-nitro-o-phenylenediamine (4-NOPD) and o-phenylenediamine (OPD) was compared using the Mouse Lymphoma Assay (MLA) with or without metabolic activation (S9). As expected, OPD was found to be a more potent mutagen than 4-NOPD. To evaluate possible mechanisms behind their mutagenic effects, the following end points were also monitored in cells that had been exposed to similar concentrations of the compounds as in the MLA: general DNA damage (using a standard protocol for the Comet assay); oxidative DNA damage (using a modified procedure for the Comet assay in combination with the enzyme hOGG1); reactive oxygen species (ROS; using the CM-H(2)DCFDA assay); and the balance of the nucleotide pool (measured after conversion to the corresponding nucleosides dC, dT, dG and dA using high-performance liquid chromatography). Both compounds increased the level of general DNA damage. Again, OPD was found to be more potent than 4-NOPD (which only increased the level of general DNA damage in the presence of S9). Although less obvious for OPD, both compounds increased the level of oxidative DNA damage. However, an increase in intracellular ROS was only observed in cells exposed to 4-NOPD, both with and without S9 (which in itself induced oxidative stress). Both compounds decreased the concentrations of dA, dT and dC. A striking effect of OPD was the sharp reduction of dA observed already at very low concentration, both with and without S9 (which in itself affected the precursor pool). Taken together, our results indicate that indirect effects on DNA, possibly related to an unbalanced nucleotide pool, mediate the mutagenicity and DNA-damaging effects of 4-NOPD and OPD to a large extent. Although induction of intracellular oxidative stress seems to be a possible mechanism behind the genotoxicity of 4-NOPD, this pathway seems to be of less importance for the more potent mutagen OPD.

  • 35.
    Aslam, Muhammad
    et al.
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Dahlberg, Olle
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Mannervik, Bengt
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Mannervik, Mattias
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Transgenic Overexpression of Glutathione Transferase E7 in Drosophila Attenuates Toxicity of Organic Isothiocyanates Affecting Survival and OvipositionManuscript (preprint) (Other academic)
    Abstract [en]

    Organic isothiocyanates (ITCs) are allelochemicals produced by plants in order to combat insects and other herbivores. The compounds are toxic electrophiles that can be inactivated and conjugated with intracellular glutathione in reactions catalyzed by glutathione transferases (GSTs). The Drosophila melanogaster GSTE7 was heterologously expressed in Escherichia coli and purified for functional studies. The enzyme showed high catalytic activity with various isothiocyanates including phenethyl isothiocyanate (PEITC) and allyl isothiocyanate (AITC), which in millimolar dietary concentrations conferred toxicity to adult D. melanogaster leading to death or a shortened life-span of the flies. In situ hybridization revealed a maternal contribution of GSTE7 transcripts to embryos, and strongest zygotic expression in the digestive tract.  Transgenesis involving the GSTE7 gene controlled by an actin promoter produced viable flies expressing the GSTE7 transcript ubiquitously. Transgenic females show a significant extension in life-span when subjected to the same PEITC treatment as the wild-type flies. By contrast, transgenic male flies showed no significant effect in the first few days, and subsequently showed a somewhat lower survival rate. At 1 mM AITC concentration, no toxicity was noted. However, the oviposition activity was dramatically enhanced from a very low level in wild-type flies reared in the presence of 1 mM AITC to values an order of magnitude higher for the transgenic flies. The results demonstrate a clear protective effect of GSTE7 against exposure to ITC allelochemicals which can affect both life-span and fecundity of female flies.

  • 36. Asmat, Tauseef M.
    et al.
    Tenenbaum, Tobias
    Jonsson, Ann-Beth
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Schwerk, Christian
    Schroten, Horst
    Impact of Calcium Signaling during Infection of Neisseria meningitidis to Human Brain Microvascular Endothelial Cells2014In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 9, no 12, p. e114474-Article in journal (Refereed)
    Abstract [en]

    The pili and outer membrane proteins of Neisseria meningitidis (meningococci) facilitate bacterial adhesion and invasion into host cells. In this context expression of meningococcal PilC1 protein has been reported to play a crucial role. Intracellular calcium mobilization has been implicated as an important signaling event during internalization of several bacterial pathogens. Here we employed time lapse calcium-imaging and demonstrated that PilC1 of meningococci triggered a significant increase in cytoplasmic calcium in human brain microvascular endothelial cells, whereas PilC1-deficient meningococci could not initiate this signaling process. The increase in cytosolic calcium in response to PilC1-expressing meningococci was due to efflux of calcium from host intracellular stores as demonstrated by using 2-APB, which inhibits the release of calcium from the endoplasmic reticulum. Moreover, pre-treatment of host cells with U73122 (phospholipase C inhibitor) abolished the cytosolic calcium increase caused by PilC1-expressing meningococci demonstrating that active phospholipase C (PLC) is required to induce calcium transients in host cells. Furthermore, the role of cytosolic calcium on meningococcal adherence and internalization was documented by gentamicin protection assay and double immunofluorescence (DIF) staining. Results indicated that chelation of intracellular calcium by using BAPTA-AM significantly impaired PilC1-mediated meningococcal adherence to and invasion into host endothelial cells. However, buffering of extracellular calcium by BAPTA or EGTA demonstrated no significant effect on meningococcal adherence to and invasion into host cells. Taken together, these results indicate that meningococci induce calcium release from intracellular stores of host endothelial cells via PilC1 and cytoplasmic calcium concentrations play a critical role during PilC1 mediated meningococcal adherence to and subsequent invasion into host endothelial cells.

  • 37. Assadi, Ghazaleh
    et al.
    Vesterlund, Liselotte
    Bonfiglio, Ferdinando
    Mazzurana, Luca
    Cordeddu, Lina
    Schepis, Danika
    Mjösberg, Jenny
    Ruhrmann, Sabrina
    Fabbri, Alessia
    Vukojevic, Vladana
    Percipalle, Piergiorgio
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute. New York University Abu Dhabi, United Arab Emirates.
    Salomons, Florian A.
    Laurencikiene, Jurga
    Törkvist, Leif
    Halfvarson, Jonas
    D'Amato, Mauro
    Functional Analyses of the Crohn's Disease Risk Gene LACC12016In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 11, no 12, article id e0168276Article in journal (Refereed)
    Abstract [en]

    Background Genetic variation in the Laccase (multicopper oxidoreductase) domain-containing 1 (LACC1) gene has been shown to affect the risk of Crohn's disease, leprosy and, more recently, ulcerative colitis and juvenile idiopathic arthritis. LACC1 function appears to promote fatty-acid oxidation, with concomitant inflammasome activation, reactive oxygen species production, and anti-bacterial responses in macrophages. We sought to contribute to elucidating LACC1 biological function by extensive characterization of its expression in human tissues and cells, and through preliminary analyses of the regulatory mechanisms driving such expression. Methods We implemented Western blot, quantitative real-time PCR, immunofluorescence microscopy, and flow cytometry analyses to investigate fatty acid metabolism-immune nexus (FAMIN; the LACC1 encoded protein) expression in subcellular compartments, cell lines and relevant human tissues. Gene-set enrichment analyses were performed to initially investigate modulatory mechanisms of LACC1 expression. A small-interference RNA knockdown in vitro model system was used to study the effect of FAMIN depletion on peroxisome function. Results FAMIN expression was detected in macrophage-differentiated THP-1 cells and several human tissues, being highest in neutrophils, monocytes/macrophages, myeloid and plasmacytoid dendritic cells among peripheral blood cells. Subcellular co-localization was exclusively confined to peroxisomes, with some additional positivity for organelle endomembrane structures. LACC1 co-expression signatures were enriched for genes involved in peroxisome proliferator-activated receptors (PPAR) signaling pathways, and PPAR ligands downregulated FAMIN expression in in vitro model systems. Conclusion FAMIN is a peroxisome-associated protein with primary role(s) in macrophages and other immune cells, where its metabolic functions may be modulated by PPAR signaling events. However, the precise molecular mechanisms through which FAMIN exerts its biological effects in immune cells remain to be elucidated.

  • 38. Aufschnaiter, Andreas
    et al.
    Habernig, Lukas
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute. University of Graz, Austria.
    Kohler, Verena
    Diessl, Jutta
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Carmona-Gutierrez, Didac
    Eisenberg, Tobias
    Keller, Walter
    Büttner, Sabrina
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute. University of Graz, Austria.
    The Coordinated Action of Calcineurin and Cathepsin D Protects Against alpha-Synuclein Toxicity2017In: Frontiers in Molecular Neuroscience, ISSN 1662-5099, Vol. 10, article id 207Article in journal (Refereed)
    Abstract [en]

    The degeneration of dopaminergic neurons during Parkinson's disease (PD) is intimately linked to malfunction of alpha-synuclein (alpha Syn), the main component of the proteinaceous intracellular inclusions characteristic for this pathology. The cytotoxicity of alpha Syn has been attributed to disturbances in several biological processes conserved from yeast to humans, including Ca2+ homeostasis, general lysosomal function and autophagy. However, the precise sequence of events that eventually results in cell death remains unclear. Here, we establish a connection between the major lysosomal protease cathepsin D (CatD) and the Ca2+/calmodulin-dependent phosphatase calcineurin. In a yeast model for PD, high levels of human alpha Syn triggered cytosolic acidification and reduced vacuolar hydrolytic capacity, finally leading to cell death. This could be counteracted by overexpression of yeast CatD (Pep4), which re-installed pH homeostasis and vacuolar proteolytic function, decreased alpha Syn oligomers and aggregates, and provided cytoprotection. Interestingly, these beneficial effects of Pep4 were independent of autophagy. Instead, they required functional calcineurin signaling, since deletion of calcineurin strongly reduced both the proteolytic activity of endogenous Pep4 and the cytoprotective capacity of overexpressed Pep4. Calcineurin contributed to proper endosomal targeting of Pep4 to the vacuole and the recycling of the Pep4 sorting receptor Pep1 from prevacuolar compartments back to the trans-Golgi network. Altogether, we demonstrate that stimulation of this novel calcineurin-Pep4 axis reduces alpha Syn cytotoxicity.

  • 39. Aufschnaiter, Andreas
    et al.
    Kohler, Verena
    Büttner, Sabrina
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute. University of Graz, Austria.
    Taking out the garbage: cathepsin D and calcineurin in neurodegeneration2017In: Neural Regeneration Research, ISSN 1673-5374, E-ISSN 1876-7958, Vol. 12, no 11, p. 1776-1779Article, review/survey (Refereed)
    Abstract [en]

    Cellular homeostasis requires a tightly controlled balance between protein synthesis, folding and degradation. Especially long-lived, post-mitotic cells such as neurons depend on an efficient proteostasis system to maintain cellular health over decades. Thus, a functional decline of processes contributing to protein degradation such as autophagy and general lysosomal proteolytic capacity is connected to several age-associated neurodegenerative disorders, including Parkinson's, Alzheimer's and Huntington's diseases. These so called proteinopathies are characterized by the accumulation and misfolding of distinct proteins, subsequently driving cellular demise. We recently linked efficient lysosomal protein breakdown via the protease cathepsin D to the Ca2+/calmodulin-dependent phosphatase calcineurin. In a yeast model for Parkinson's disease, functional calcineurin was required for proper trafficking of cathepsin D to the lysosome and for recycling of its endosomal sorting receptor to allow further rounds of shuttling. Here, we discuss these findings in relation to present knowledge about the involvement of cathepsin D in proteinopathies in general and a possible connection between this protease, calcineurin signalling and endosomal sorting in particular. As dysregulation of Ca2+ homeostasis as well as lysosomal impairment is connected to a plethora of neurodegenerative disorders, this novel interplay might very well impact pathologies beyond Parkinson's disease.

  • 40. Aufschnaiter, Andreas
    et al.
    Kohler, Verena
    Diessl, Jutta
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Peselj, Carlotta
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Carmona-Gutierrez, Didac
    Keller, Walter
    Büttner, Sabrina
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute. University of Graz, Austria.
    Mitochondrial lipids in neurodegeneration2017In: Cell and Tissue Research, ISSN 0302-766X, E-ISSN 1432-0878, Vol. 367, no 1, p. 125-140Article, review/survey (Refereed)
    Abstract [en]

    Mitochondrial dysfunction is a common feature of many neurodegenerative diseases, including proteinopathies such as Alzheimer's or Parkinson's disease, which are characterized by the deposition of aggregated proteins in the form of insoluble fibrils or plaques. The distinct molecular processes that eventually result in mitochondrial dysfunction during neurodegeneration are well studied but still not fully understood. However, defects in mitochondrial fission and fusion, mitophagy, oxidative phosphorylation and mitochondrial bioenergetics have been linked to cellular demise. These processes are influenced by the lipid environment within mitochondrial membranes as, besides membrane structure and curvature, recruitment and activity of different proteins also largely depend on the respective lipid composition. Hence, the interaction of neurotoxic proteins with certain lipids and the modification of lipid composition in different cell compartments, in particular mitochondria, decisively impact cell death associated with neurodegeneration. Here, we discuss the relevance of mitochondrial lipids in the pathological alterations that result in neuronal demise, focussing on proteinopathies.

  • 41. Aufschnaiter, Andreas
    et al.
    Kohler, Verena
    Walter, Corvin
    Tosal-Castano, Sergi
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Habernig, Lukas
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Wolinski, Heimo
    Keller, Walter
    Vögtle, F-Nora
    Büttner, Sabrina
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute. University of Graz, Austria.
    The Enzymatic Core of the Parkinson's Disease-Associated Protein LRRK2 Impairs Mitochondria Biogenesis in Aging Yeast2018In: Frontiers in Molecular Neuroscience, ISSN 1662-5099, Vol. 11, article id 205Article in journal (Refereed)
    Abstract [en]

    Mitochondrial dysfunction is a prominent trait of cellular decline during aging and intimately linked to neuronal degeneration during Parkinson's disease (PD). Various proteins associated with PD have been shown to differentially impact mitochondrial dynamics, quality control and function, including the leucine-rich repeat kinase 2 (LRRK2). Here, we demonstrate that high levels of the enzymatic core of human LRRK2, harboring GTPase as well as kinase activity, decreases mitochondrial mass via an impairment of mitochondria! biogenesis in aging yeast. We link mitochondrial depletion to a global downregulation of mitochondria-related gene transcripts and show that this catalytic core of LRRK2 localizes to mitochondria and selectively compromises respiratory chain complex IV formation. With progressing cellular age, this culminates in dissipation of mitochondrial transmembrane potential, decreased respiratory capacity, ATP depletion and generation of reactive oxygen species. Ultimately, the collapse of the mitochondrial network results in cell death. A point mutation in LRRK2 that increases the intrinsic GTPase activity diminishes mitochondrial impairment and consequently provides cytoprotection. In sum, we report that a downregulation of mitochondrial biogenesis rather than excessive degradation of mitochondria underlies the reduction of mitochondrial abundance induced by the enzymatic core of LRRK2 in aging yeast cells. Thus, our data provide a novel perspective for deciphering the causative mechanisms of LRRK2-associated PD pathology.

  • 42.
    Bajinskis, Ainars
    et al.
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Natarajan, Adayapalam T.
    Erixon, Klaus
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Harms-Ringdahl, Mats
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    DNA double strand breaks induced by the indirect effect of radiation are more efficiently repaired by non-homologous end joining compared to homologous recombination repair2013In: Mutation research. Genetic toxicology and environmental mutagenesis, ISSN 1383-5718, E-ISSN 1879-3592, Vol. 756, no 1-2, p. 21-29Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to investigate the relative involvement of three major DNA repair pathways, i.e., non-homologous end joining (NHEJ), homologous recombination (HRR) and base excision (BER) in repair of DNA lesions of different complexity induced by low- or high-LET radiation with emphasis on the contribution of the indirect effect of radiation for these radiation qualities. A panel of DNA repair-deficient CHO cell lines was irradiated by Cs-137 gamma-rays or radon progeny alpha-particles. Irradiation was also performed in the presence of 2 M DMSO to reduce the indirect effect of radiation and the complexity of the DNA damage formed. Clonogenic survival and micronucleus assays were used to estimate efficiencies of the different repair pathways for DNA damages produced by direct and indirect effects. Removal of the indirect effect of low-LET radiation by DMSO increased clonogenic survival and decreased MN formation for all cell lines investigated. A direct contribution of the indirect effect of radiation to DNA base damage was suggested by the significant protection by DMSO seen for the BER deficient cell line. Lesions formed by the indirect effect are more readily repaired by the NHEJ pathway than by HRR after irradiation with gamma-rays or alpha-particles as evaluated by cell survival and the yields of MN. The results obtained with BER- and NHEJ-deficient cells suggest that the indirect effect of radiation contributes significantly to the formation of repair substrates for these pathways.

  • 43.
    Balogun, Halima A.
    et al.
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Awah, Nancy
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Nilsson, Sandra
    Rogier, Christophe
    Trape, Jean-Francois
    Chen, Qijun
    Roussilhon, Christian
    Berzins, Klavs
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Pattern of antibodies to the Duffy binding like domain of Plasmodium falciparum antigen Pf332 in Senegalese individuals2014In: Acta Tropica, ISSN 0001-706X, E-ISSN 1873-6254, Vol. 130, p. 80-87Article in journal (Refereed)
    Abstract [en]

    Acquisition of antibodies against blood stage antigens is crucial in malaria immunity and the Plasmodium falciparum antigen Pf332, which is present in close association with the infected red blood cell membrane, is one such antigen. In this study, the antibody response to a Duffy binding like fragment of Pf332, termed Pf332-DBL was investigated in sera from naturally exposed individuals living in Dielmo village, Senegal, with regard to immunoglobulin classes (IgG, IgM, IgE) and IgG subclasses (IgG1-4). While the levels of IgM, IgG, IgG1 and IgG2 only displayed a moderate trend to increase with age, Pf332-DBL specific IgG3 levels increased significantly in the older villagers. In multivariate analysis, when controlling for confounding factors, and in a linear model with a Poisson distribution, anti-Pf332-DBL IgG3 as well as the ratio of cytophilic to non cytophilic anti-Pf332-DBL antibodies were found significantly associated with a reduced risk of malaria attack. This association was also present when the IgG3:IgG1 ratio was tested. Finally, two subgroups of villagers with the same mean age, were delineated by IgG3 concentrations either lower or higher than the median value. A total of 45.2% of the individuals with low anti-Pf332-DBL-IgG3 levels but only 21.4% of the villagers in the group with high levels of such antibodies had a clinical malaria attack during a period of 3 years of continuous follow-up after the blood sampling. In conclusion, Pf332-DBL induces naturally the acquisition of antibodies, and Pf332-DBL-specific IgG3 appears to be associated with protection against malaria in this endemic setting.

  • 44.
    Barragan, Antonio
    et al.
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute. Karolinska Institutet, Sweden.
    Weidner, Jessica M.
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute. Karolinska Institutet, Sweden.
    Jin, Z.
    Korpi, E. R.
    Birnir, B.
    GABAergic signalling in the immune system2015In: Acta Physiologica, ISSN 1748-1708, E-ISSN 1748-1716, Vol. 213, no 4, p. 819-827Article, review/survey (Refereed)
    Abstract [en]

    The GABAergic system is the main inhibitory neurotransmitter system in the central nervous system (CNS) of vertebrates. Signalling of the transmitter c-aminobutyric acid (GABA) via GABA type A receptor channels or G-protein-coupled type B receptors is implicated in multiple CNS functions. Recent findings have implicated the GABAergic system in immune cell functions, inflammatory conditions and diseases in peripheral tissues. Interestingly, the specific effects may vary between immune cell types, with stage of activation and be altered by infectious agents. GABA/GABA-A receptor-mediated immunomodulatory functions have been unveiled in immune cells, being present in T lymphocytes and regulating the migration of Toxoplasma-infected dendritic cells. The GABAergic system may also play a role in the regulation of brain resident immune cells, the microglial cells. Activation of microglia appears to regulate the function of GABAergic neurotransmission in neighbouring neurones through changes induced by secretion of brain-derived neurotrophic factor. The neurotransmitter-driven immunomodulation is a new but rapidly growing field of science. Herein, we review the present knowledge of the GABA signalling in immune cells of the periphery and the CNS and raise questions for future research.

  • 45. Barregard, Lars
    et al.
    Haghdoost, Siamak
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Cooke, Marcus S.
    Human and Methodological Sources of Variability in the Measurement of Urinary 8-Oxo-7,8-dihydro-2 '-deoxyguanosine2013In: Antioxidants and Redox Signaling, ISSN 1523-0864, E-ISSN 1557-7716, Vol. 18, no 18, p. 2377-2391Article in journal (Refereed)
    Abstract [en]

    Aims: Urinary 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) is a widely used biomarker of oxidative stress. However, variability between chromatographic and ELISA methods hampers interpretation of data, and this variability may increase should urine composition differ between individuals, leading to assay interference. Furthermore, optimal urine sampling conditions are not well defined. We performed inter-laboratory comparisons of 8-oxodG measurement between mass spectrometric-, electrochemical- and ELISA-based methods, using common within-technique calibrants to analyze 8-oxodG-spiked phosphate-buffered saline and urine samples. We also investigated human subject- and sample collection-related variables, as potential sources of variability. Results: Chromatographic assays showed high agreement across urines from different subjects, whereas ELISAs showed far more inter-laboratory variation and generally overestimated levels, compared to the chromatographic assays. Excretion rates in timed 'spot' samples showed strong correlations with 24 h excretion (the 'gold' standard) of urinary 8-oxodG (r(p) 0.67-0.90), although the associations were weaker for 8-oxodG adjusted for creatinine or specific gravity (SG). The within-individual excretion of 8-oxodG varied only moderately between days (CV 17% for 24 h excretion and 20% for first void, creatinine-corrected samples). Innovation: This is the first comprehensive study of both human and methodological factors influencing 8-oxodG measurement, providing key information for future studies with this important biomarker. Conclusion: ELISA variability is greater than chromatographic assay variability, and cannot determine absolute levels of 8-oxodG. Use of standardized calibrants greatly improves intra-technique agreement and, for the chromatographic assays, importantly allows integration of results for pooled analyses. If 24 h samples are not feasible, creatinine- or SG-adjusted first morning samples are recommended.

  • 46.
    Behm, Mikaela
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute. Stockholms universitet.
    Regulation of RNA Editing: The impact of inosine on the neuronal transcriptome2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The transcriptome of the mammalian brain is extensively modified by adenosine to inosine (A-to-I) nucleotide conversion by two adenosine deaminases (ADAR1 and ADAR2). As adenosine and inosine have different base pairing properties, A-to-I RNA editing shapes the functional output of both coding and non-coding RNAs (ncRNAs) in the brain. The aim of this thesis was to identify editing events in small regulatory ncRNAs (miRNAs) and to determine their temporal and spatial editing status in the developing and adult mouse brain. To do this, we initially analyzed the editing status of miRNAs from different developmental time points of the mouse brain. We detected novel miRNA substrates subjected to A-to-I editing and found a general increase in miRNA editing during brain development, implicating a more stringent control of miRNAs as the brain matures. Most of the edited miRNAs were found to be transcribed as a single long consecutive transcript from a large gene cluster. However, maturation from this primary miRNA (pri-miRNA) transcript into functional forms of miRNAs is regulated individually, and might be influenced by the ADAR proteins in an editing independent matter. We also found that edited miRNAs were highly expressed at the synapse, implicating a role as local regulators of synaptic translation. We further show that the increase in editing during development is explained by a gradual accumulation of the ADAR enzymes in the nucleus. Specifically for ADAR2, we found a developmentally increasing interaction with two factors, importin-α4 and Pin1, that facilitate nuclear localization of the editing enzyme. We have also found that selectively edited stem loops often are flanked by other long stem loop structures that induce editing in cis. This may explain why multiple pri-miRNAs are edited within the same cluster. In conclusion, this thesis has significantly increased the understanding of the dynamics of both editing substrates and enzymes in the developing and mature brain.

  • 47.
    Behm, Mikaela
    et al.
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Fritzell, Kajsa
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Pessa, Heli
    Mackowiak, Sebastian
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Ekdahl, Ylva
    Kang, Wenjing
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Biryukova, Inna
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    von Euler, Anne
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Visa, Neus
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Friedländer, Marc
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Öhman, Marie
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Synaptic expression and regulation of miRNA editing in the brainManuscript (preprint) (Other academic)
    Abstract [en]

    In the brain, sophisticated networks of RNA regulatory events tightly control gene expression in order to achieve proper brain function. We and others have previously shown that several miRNAs, encoded within the miR-379-410 cluster, are subjected to A-to-I RNA editing. In the present study we conclude these edited miRNAs to be transcribed as a single long consecutive transcript, however the maturation into functional forms of miRNAs is regulated individually. In seven of the miRNAs, subjected to editing, we analyze how editing relates to miRNA maturation. Of particular interest has been maturation of miR-381-3p and miR-376b-3p, both important for neuronal plasticity, dendrite outgrowth and neuronal homeostasis. Most of the edited miRNAs from the cluster, are highly edited in their unprocessed primary transcript, including miR-381-3p and miR-376b-3p. However, editing in miR-381-3p is almost entirely absent in the mature form, while editing is increased in the mature form of miR-376b-3p compared to the primary transcript. We propose that ADAR1 positively influences the maturation of pri-miR-381 in an editing independent manner. In pri-miR-376b we hypothesize that ADAR1 and ADAR2 competes for editing, and while ADAR2 inhibits miRNA maturation, ADAR1 editing is frequently present in the mature miR-376b-3p. We further show that miR-381-3p and miR-376b-3p regulate the dendritically expressed Pumilio 2 (Pum2) protein. By next generation RNA sequencing (NGS RNA-seq) on purified synaptoneurosomes, we show that miR-381-3p is highly expressed at the synapse, suggesting its functional role in locally regulating Pum2. Furthermore, we identify a set of highly expressed miRNAs at the synapse, which may act locally to target synaptic mRNAs.

  • 48.
    Behm, Mikaela
    et al.
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Wahlstedt, Helene
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Widmark, Albin
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Eriksson, Maria
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Öhman, Marie
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Accumulation of nuclear ADAR2 regulates A-to-I RNA editing during neuronal development2017In: Journal of Cell Science, ISSN 0021-9533, E-ISSN 1477-9137, Vol. 130, p. 745-753Article in journal (Refereed)
    Abstract [en]

    Adenosine to inosine (A-to-I) RNA editing is important for a functional brain, and most known sites that are subject to selective RNA editing have been found to result in diversified protein isoforms that are involved in neurotransmission. In the absence of the active editing enzymes ADAR1 or ADAR2 (also known as ADAR and ADARB1, respectively), mice fail to survive until adulthood. Nuclear A-to-I editing of neuronal transcripts is regulated during brain development, with low levels of editing in the embryo and a dramatic increase after birth. Yet, little is known about the mechanisms that regulate editing during development. Here, we demonstrate lower levels of ADAR2 in the nucleus of immature neurons than in mature neurons. We show that importin-a4 (encoded by Kpna3), which increases during neuronal maturation, interacts with ADAR2 and contributes to the editing efficiency by bringing it into the nucleus. Moreover, we detect an increased number of interactions between ADAR2 and the nuclear isomerase Pin1 as neurons mature, which contribute to ADAR2 protein stability. Together, these findings explain how the nuclear editing of substrates that are important for neuronal function can increase as the brain develops. 

  • 49.
    Behm, Mikaela
    et al.
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Öhman, Marie
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    RNA Editing: A Contributor to Neuronal Dynamics in the Mammalian Brain2016In: Trends in Genetics, ISSN 0168-9525, E-ISSN 1362-4555, Vol. 32, no 3, p. 165-175Article, review/survey (Refereed)
    Abstract [en]

    Post-transcriptional RNA modification by adenosine to inosine (A-to-I) editing expands the functional output of many important neuronally expressed genes. The mechanism provides flexibility in the proteome by expanding the variety of isoforms, and is a requisite for neuronal function. Indeed, targets for editing include key mediators of synaptic transmission with an overall significant effect on neuronal signaling. In addition, editing influences splice-site choice and miRNA targeting capacity, and thereby regulates neuronal gene expression. Editing efficiency at most of these sites increases during neuronal differentiation and brain maturation in a spatiotemporal manner. This editing-induced dynamics in the transcriptome is essential for normal brain development, and we are only beginning to understand its role in neuronal function. In this review we discuss the impact of RNA editing in the brain, with special emphasis on the physiological consequences for neuronal development and plasticity.

  • 50.
    Belikov, Sergey
    et al.
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Lackmann, Fredrik
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Wieslander, Lars
    Stockholm University, Faculty of Science, Department of Molecular Biosciences, The Wenner-Gren Institute.
    Incorrect assignment of affected nucleotides in footprinting/probing experiments2017In: BioTechniques, ISSN 0736-6205, E-ISSN 1940-9818, Vol. 63, no 3, p. 105-106Article in journal (Refereed)
1234567 1 - 50 of 616
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