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Boulet, Nathalie
Publications (5 of 5) Show all publications
Bokhari, M. H., Halleskog, C., Åslund, A., Boulet, N., Casadesús Rendos, E., de Jong, J. M., . . . Bengtsson, T. (2021). Isothermal microcalorimetry measures UCP1-mediated thermogenesis in mature brite adipocytes. Communications Biology, 4(1), Article ID 1108.
Open this publication in new window or tab >>Isothermal microcalorimetry measures UCP1-mediated thermogenesis in mature brite adipocytes
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2021 (English)In: Communications Biology, E-ISSN 2399-3642, Vol. 4, no 1, article id 1108Article in journal (Refereed) Published
Abstract [en]

The activation of thermogenesis in adipose tissue has emerged as an important target for the development of novel anti-obesity therapies. Using multi-well isothermal microcalorimetry, we have demonstrated that mature murine brown and brite adipocytes produce quantifiable heat upon β3-AR stimulation, independently of any anaerobic mechanisms. Additionally, in brite adipocytes lacking UCP1 protein, β3-AR stimulation still induces heat production, albeit to a much lower extent than in their wildtype counterparts, suggesting that UCP1 is an essential component of adrenergic induced thermogenesis in murine brite adipocytes exvivo. Similarly, we could observe an increase in heat production in human-derived adipocytes (hMADS) upon β-AR stimulation. Collectively, these results establish the use of isothermal microcalorimetry as a sensitive and accurate technique for measuring thermogenic responses in intact mature brite adipocytes from murine and human origin.

National Category
Biological Sciences
Identifiers
urn:nbn:se:su:diva-198698 (URN)10.1038/s42003-021-02639-4 (DOI)000697665400003 ()34548622 (PubMedID)
Available from: 2021-11-15 Created: 2021-11-15 Last updated: 2022-02-28Bibliographically approved
Boulet, N., Luijten, I. H. N., Cannon, B. & Nedergaard, J. (2021). Thermogenic recruitment of brown and brite/beige adipose tissues is not obligatorily associated with macrophage accretion or attrition. American Journal of Physiology. Endocrinology and Metabolism, 320(2), E359-E378
Open this publication in new window or tab >>Thermogenic recruitment of brown and brite/beige adipose tissues is not obligatorily associated with macrophage accretion or attrition
2021 (English)In: American Journal of Physiology. Endocrinology and Metabolism, ISSN 0193-1849, E-ISSN 1522-1555, Vol. 320, no 2, p. E359-E378Article in journal (Refereed) Published
Abstract [en]

Cold- and diet-induced recruitment of brown adipose tissue (BAT) and the browning of white adipose tissue (WAT) are dynamic processes, and the recruited state attained is a state of dynamic equilibrium, demanding continuous stimulation to be maintained. An involvement of macrophages, classical proinflammatory (M1) or alternatively activated anti-inflammatory (M2), is presently discussed as being an integral part of these processes. If these macrophages play a mediatory role in the recruitment process, such an involvement would have to be maintained in the recruited state. We have, therefore, investigated whether the recruited state of these tissues is associated with macrophage accretion or attrition. We found no correlation (positive or negative) between total UCP1 mRNA levels (as a measure of recruitment) and proinflammatory macrophages in any adipose depot. We found that in young chow-fed mice, cold-induced recruitment correlated with accretion of anti-inflammatory macrophages; however, such a correlation was not seen when cold-induced recruitment was studied in diet-induced obese mice. Furthermore, the anti-inflammatory macrophage accretion was mediated via β12-adrenergic receptors; yet, in their absence, and thus in the absence of macrophage accretion, recruitment proceeded normally. We thus conclude that the classical recruited state in BAT and inguinal (brite/beige) WAT is not paralleled by macrophage accretion or attrition. Our results make mediatory roles for macrophages in the recruitment process less likely.

NEW & NOTEWORTHY A regulatory or mediatory role—positive or negative—for macrophages in the recruitment of brown adipose tissue is presently discussed. As the recruited state in the tissue is a dynamic process, maintenance of the recruited state would need persistent alterations in macrophage complement. Contrary to this expectation, we demonstrate here an absence of alterations in macrophage complement in thermogenically recruited brown—or brite/beige—adipose tissues. Macrophage regulation of thermogenic capacity is thus less likely.

Keywords
brown adipose tissue, cold, macrophages, obesity
National Category
Biological Sciences
Identifiers
urn:nbn:se:su:diva-193878 (URN)10.1152/ajpendo.00352.2020 (DOI)000629646200009 ()33284094 (PubMedID)
Available from: 2021-06-09 Created: 2021-06-09 Last updated: 2022-02-25Bibliographically approved
Luijten, I. H. N., Brooks, K., Boulet, N., Shabalina, I. G., Jaiprakash, A., Carlsson, B., . . . Nedergaard, J. (2019). Glucocorticoid-Induced Obesity Develops Independently of UCP1. Cell Reports, 27(6), 1686-1698
Open this publication in new window or tab >>Glucocorticoid-Induced Obesity Develops Independently of UCP1
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2019 (English)In: Cell Reports, E-ISSN 2211-1247, Vol. 27, no 6, p. 1686-1698Article in journal (Refereed) Published
Abstract [en]

An excess of glucocorticoids leads to the development of obesity in both mice and humans, but the mechanism for this is unknown. Here, we determine the extent to which decreased BAT thermogenic capacity (as a result of glucocorticoid treatment) contributes to the development of obesity. Contrary to previous suggestions, we show that only in mice housed at thermoneutrality (30 degrees C) does corticosterone treatment reduce total BAT UCP1 protein. This reduction is reflected in reduced brown adipocyte cellular and mitochondrial UCP1-dependent respiration. However, glucocorticoid-induced obesity develops to the same extent in animals housed at 21 degrees C and 30 degrees C, whereas total BAT UCP1 protein levels differ 100-fold between the two groups. In corticosterone-treated wild-type and UCP1 knockout mice housed at 30 degrees C, obesity also develops to the same extent. Thus, our results demonstrate that the development of glucocorticoid-induced obesity is not caused by a decreased UCP1-dependent thermogenic capacity.

National Category
Biological Sciences
Identifiers
urn:nbn:se:su:diva-169257 (URN)10.1016/j.celrep.2019.04.041 (DOI)000467058500006 ()31067456 (PubMedID)
Available from: 2019-06-12 Created: 2019-06-12 Last updated: 2024-01-17Bibliographically approved
de Jong, J. M. A., Wouters, R. T. F., Boulet, N., Cannon, B., Nedergaard, J. & Petrovic, N. (2017). The β3-adrenergic receptor is dispensable for browning of adipose tissues. American Journal of Physiology. Endocrinology and Metabolism, 312(6), E508-E518
Open this publication in new window or tab >>The β3-adrenergic receptor is dispensable for browning of adipose tissues
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2017 (English)In: American Journal of Physiology. Endocrinology and Metabolism, ISSN 0193-1849, E-ISSN 1522-1555, Vol. 312, no 6, p. E508-E518Article in journal (Refereed) Published
Abstract [en]

Brown and brite/beige adipocytes are attractive therapeutic targets to treat metabolic diseases. To maximally utilize their functional potential, further understanding is required about their identities and their functional differences. Recent studies with β3-adrenergic receptor knockout mice reported that brite/beige adipocytes, but not classical brown adipocytes, require the β3-adrenergic receptor for cold-induced transcriptional activation of thermogenic genes. We aimed to further characterize this requirement of the β3-adrenergic receptor as a functional distinction between classical brown and brite/beige adipocytes. However, when comparing wild-type and β3-adrenergic receptor knockout mice, we observed no differences in cold-induced thermogenic gene expression (Ucp1, Pgc1a, Dio2 and Cidea) in brown or white (brite/beige) adipose tissues. Irrespective of the duration of the cold exposure or the sex of the mice, we observed no effect of the absence of the β3-adrenergic receptor. Experiments with the β3-adrenergic receptor agonist CL-316,243 verified the functional absence of β3-adrenergic signaling in these knockout mice. The β3-adrenergic receptor knockout model in the present study was maintained on a FVB/N background, whereas earlier reports used C57BL/6 and 129Sv mice. Thus, our data imply background-dependent differences in adrenergic signaling mechanisms in response to cold exposure. Nonetheless, the present data indicate that the β3-adrenergic receptor is dispensable for cold-induced transcriptional activation in both classical brown and, as opposed to earlier studies, brite/beige cells. This should be taken into account in the increasing number of studies on the induction of browning and their extrapolation to human physiology.

Keywords
β3-adrenergic receptor, adipose browning, brown adipocytes, brite/beige adipocytes, UCP
National Category
Cell Biology
Research subject
Physiology
Identifiers
urn:nbn:se:su:diva-140882 (URN)10.1152/ajpendo.00437.2016 (DOI)000404391300005 ()28223294 (PubMedID)
Available from: 2017-03-21 Created: 2017-03-21 Last updated: 2022-02-28Bibliographically approved
Luijten, I., Brooks, K., Boulet, N., Shabalina, I., Jaiprakash, A., Carlsson, B., . . . Nedergaard, J.Glucocorticoid-induced obesity develops independently of UCP1.
Open this publication in new window or tab >>Glucocorticoid-induced obesity develops independently of UCP1
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(English)Manuscript (preprint) (Other academic)
Abstract [en]

An excess of glucocorticoids is associated with the development of obesity, as is evident from the accumulation of visceral fat in patients suffering from Cushing’s Syndrome. Activated brown adipose tissue (BAT) reduces metabolic efficiency; correspondingly an inactivation of BAT has been proposed to cause glucocorticoid-induced obesity. Here we determine the extent to which changes in BAT function as a result of glucocorticoid treatment contribute to the simultaneous development of obesity. In mice housed at 21 °C and treated with corticosterone for 2 weeks (CORT), we unexpectedly found no change in total BAT uncoupling protein 1 (UCP1) protein levels or in non-shivering thermogenic capacity. In mice housed at thermoneutrality, a humanized condition, we did observe a reduction in total UCP1 protein levels in BAT in response to CORT, which was reflected in reduced brown adipocyte cellular and mitochondrial UCP1-dependent respiration. However, glucocorticoid-induced obesity developed to the same extent in animals housed at 21 °C and 30 °C, while total BAT UCP1 protein levels differed 100-fold between the two groups. In wild-type and UCP1 knock-out mice housed at 30 °C and treated with CORT, obesity also developed to the same extent. Thus, contrary to what has previously been suggested, our results show that the development of glucocorticoid-induced obesity is unrelated to the presence of UCP1.

Keywords
uncoupling protein 1, corticosterone, obesity, thermogenesis, energy balance, brown adipose tissue, thermoneutrality, cold exposure
National Category
Biochemistry and Molecular Biology
Research subject
Molecular Bioscience
Identifiers
urn:nbn:se:su:diva-163421 (URN)
Funder
Swedish Research Council
Available from: 2019-01-02 Created: 2019-01-02 Last updated: 2022-02-26Bibliographically approved
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