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Perturbations of model membranes induced by pathogenic dynorphin A mutants causing neurodegeneration in human brain
Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
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2011 (English)In: Biochemical and Biophysical Research Communications - BBRC, ISSN 0006-291X, E-ISSN 1090-2104, Vol. 411, no 1, 111-114 p.Article in journal (Refereed) Published
Abstract [en]

Several effects of the endogenous opioid peptide dynorphin A (Dyn A) are not mediated through the opioid receptors. These effects are generally excitatory, and result in cell loss and induction of chronic pain and paralysis. The mechanism(s) is not well defined but may involve formation of pores in cellular membranes. In the 17-amino acid peptide Dyn A we have recently identified L5S, R6W, and R9C mutations that cause the dominantly inherited neurodegenerative disorder Spinocerebellar ataxia type 23. To gain further insight into non-opioid neurodegenerative mechanism(s), we studied the perturbation effects on lipid bilayers of wild type Dyn A and its mutants in large unilamellar phospholipid vesicles encapsulating the fluorescent dye calcein. The peptides were found to induce calcein leakage from uncharged and negatively charged vesicles to different degrees, thus reflecting different membrane perturbation effects. The mutant Dyn A R6W was the most potent in producing leakage with negatively charged vesicles whereas Dyn A L5S was virtually inactive. The overall correlation between membrane perturbation and neurotoxic response [3] suggests that pathogenic Dyn A actions may be mediated through transient pore formation in lipid domains of the plasma membrane.

Place, publisher, year, edition, pages
2011. Vol. 411, no 1, 111-114 p.
Keyword [en]
Prodynorphin, Dynorphin A, Spinocerebellar ataxia, Non-opioid activity, Large unilamellar vesicle, Calcein leakage
National Category
Biological Sciences
Identifiers
URN: urn:nbn:se:su:diva-66588DOI: 10.1016/j.bbrc.2011.06.105ISI: 000293368000019OAI: oai:DiVA.org:su-66588DiVA: diva2:468542
Note
authorCount :6Available from: 2011-12-21 Created: 2011-12-20 Last updated: 2017-12-08Bibliographically approved
In thesis
1. Biophysical studies of peptides with functions in biotechnology and biology
Open this publication in new window or tab >>Biophysical studies of peptides with functions in biotechnology and biology
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

My thesis concerns spectroscopic studies (NMR, CD and fluorescence) of peptides with functions in biotechnology and biology, and their interactions with a model membrane (large unilamellar phospholipid vesicles).

The resorufin-based arsenical hairpin binder (ReAsH) bound to a short peptide is a useful fluorescent tag for genetic labeling of proteins in living cells. A hairpin structure with some resemblance to type II β-turn was determined by NMR structure calculations (Paper I).

Cell-penetrating peptides (CPPs) are short (30-35 residues), often rich in basic amino acids such as Arg. They can pass through the cell membrane and deliver bioactive cargoes, making them useful for biotechnical and pharmacological applications. The mechanisms of cellular uptake and membrane translocation are under debate. Understanding the mechanistic aspects of CPPs is the major focus of Papers II, III, and IV.

The effect of the pyrenebutyrate (PB) on the cellular uptake, membrane translocation and perturbation of several CPPs from different subgroups was investigated (Paper II). We concluded that both charge and hydrophobicity of the CPP affect the cellular uptake and membrane translocation efficiency.

Endosomal escape is a crucial challenge for the CPP applications. We modeled the endosome and endosomal escape for different CPPs to investigate the corresponding molecular mechanisms (Papers III and IV). Hydrophobic CPPs were able to translocate across the model membrane in the presence of a pH gradient, produced by bacteriorhodopsin proton pumping, whereas a smaller effect was observed for hydrophilic CPPs.

Dynorphin A (Dyn A) peptide mutations are associated with neurodegenerative disorders, without involvement of the opioid receptors. The non-opioid activities of Dyn A may involve membrane perturbations. Model membrane-perturbations by three Dyn A mutants were investigated (Paper V). The results showed effects to different degrees largely in accordance with their neurotoxic effects.

Place, publisher, year, edition, pages
Stockholm: Department of Biochemistry and Biophysics, Stockholm University, 2012. 75 p.
Keyword
Genetic fluorescence label, Biarsenical tetracysteine motif, Cell-penetrating peptides, Large unilamellar vesicles, Pyrenebutyrate, Endosomal escape, Membrane perturbation, Bacteriorhodopsin, Dynorphin
National Category
Biophysics
Research subject
Biophysics
Identifiers
urn:nbn:se:su:diva-66948 (URN)978-91-7447-417-6 (ISBN)
Public defence
2012-02-14, Magnélisalen, Kemiska övningslaboratoriet, Svante Arrhenius väg 16 B, Stockholm, 10:00 (English)
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Note

At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 4: Manuscript.

Available from: 2012-01-23 Created: 2011-12-22 Last updated: 2013-04-09Bibliographically approved

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