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- Kallin, Anders, et al.
(författare)
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SREBP-1 regulates the expression of heme oxygenase 1 and the phosphatidylinositol-3 kinase regulatory subunit p55 gamma
- 2007
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Ingår i: Journal of Lipid Research. - 0022-2275 .- 1539-7262. ; 48:7, s. 1628-1636
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Tidskriftsartikel (refereegranskat)abstract
- Sterol-regulatory element binding proteins (SREBPs) control the expression of genes involved in fatty acid and cholesterol biosynthesis. Using microarrays, we observed that mature SREBP-1 also induced the expression of genes unrelated to lipid metabolism, such as heme oxygenase 1 (HMOX1), plasma glutathione peroxidase, the phosphatidylinositol-3 kinase regulatory subunit p55 gamma, synaptic vesicle glycoprotein 2A, and COTE1. The expression of these genes was repressed upon addition of sterols, which block endogenous SREBP cleavage, and was induced by the statin drug mevinolin. Stimulation of fibroblasts with platelet-derived growth factor, which activates SREBP-1, had a similar effect. Fasted mice that were refed with a high-carbohydrate diet presented an increased expression of HMOX1 and p55 gamma in the liver. Overall, the transcriptional signature of SREBP-1 in fibroblasts stimulated by growth factors was very similar to that described in liver cells. We analyzed the HMOX1 promoter and found one SREBP binding site of the E-box type, which was required for regulation by SREBP-1a and SREBP-1c but was insensitive to SREBP-2. In conclusion, our data suggest that SREBP-1 regulates the expression of stress response and signaling genes, which could contribute to the metabolic response to insulin and growth factors in various tissues.
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| 2. |
- Lefranc, Clara, et al.
(författare)
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Adipocyte-Mineralocorticoid Receptor Alters Mitochondrial Quality Control Leading to Mitochondrial Dysfunction and Senescence of Visceral Adipose Tissue
- 2021
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Ingår i: International Journal of Molecular Sciences. - : MDPI. - 1661-6596 .- 1422-0067. ; 22:6
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Tidskriftsartikel (refereegranskat)abstract
- Mineralocorticoid receptor (MR) expression is increased in the adipose tissue (AT) of obese patients and animals. We previously demonstrated that adipocyte-MR overexpression in mice (Adipo-MROE mice) is associated with metabolic alterations. Moreover, we showed that MR regulates mitochondrial dysfunction and cellular senescence in the visceral AT of obese db/db mice. Our hypothesis is that adipocyte-MR overactivation triggers mitochondrial dysfunction and cellular senescence, through increased mitochondrial oxidative stress (OS). Using the Adipo-MROE mice with conditional adipocyte-MR expression, we evaluated the specific effects of adipocyte-MR on global and mitochondrial OS, as well as on OS-induced damage. Mitochondrial function was assessed by high throughput respirometry. Molecular mechanisms were probed in AT focusing on mitochondrial quality control and senescence markers. Adipo-MROE mice exhibited increased mitochondrial OS and altered mitochondrial respiration, associated with reduced biogenesis and increased fission. This was associated with OS-induced DNA-damage and AT premature senescence. In conclusion, targeted adipocyte-MR overexpression leads to an imbalance in mitochondrial dynamics and regeneration, to mitochondrial dysfunction and to ageing in visceral AT. These data bring new insights into the MR-dependent AT dysfunction in obesity.
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| 3. |
- Taveau, Christopher, et al.
(författare)
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Vasopressin and hydration play a major role in the development of glucose intolerance and hepatic steatosis in obese rats
- 2015
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Ingår i: Diabetologia. - : Springer Science and Business Media LLC. - 1432-0428 .- 0012-186X. ; 58:5, s. 1081-1090
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Tidskriftsartikel (refereegranskat)abstract
- Aims/hypothesis High plasma copeptin, a marker of vasopressin (VP) secretion, has been shown to be associated with the metabolic syndrome and development of type 2 diabetes in humans. The present study was designed to determine the long-term influence of plasma VP concentration in a rodent model prone to metabolic dysfunction. Methods Obese Zucker rats and their lean counterparts were submitted for 4 weeks to one of three protocols inducing different levels of VP. Circulating VP was either reduced by increasing the daily water intake (low-VP), or increased by a chronic i.p. infusion of VP (high-VP). The control rats had normal VP levels that depended on their own regulation of water intake and VP secretion. Results Compared with controls with normal VP, lean rats with high-VP had a higher fasting glycaemia after 4 weeks. In obese rats, high-VP promoted hyperinsulinaemia, glucose intolerance, assessed by glucose and insulin tolerance tests, and an impaired response to a pyruvate challenge. Conversely, treatment with a selective arginine vasopressin receptor 1A (V1aR) antagonist reduced glucose intolerance. Low-VP obese rats had unchanged glucose tolerance but exhibited a drastic decrease in liver steatosis compared with control obese rats, associated with low hepatic triacylglycerol and cholesterol content, and reduced expression of hepatic lipogenic genes. These effects were independent of changes in body adiposity, and plasma sodium and osmolality did not differ among groups. Conclusion/interpretation These findings show a causal relationship between the VP-hydration axis and the metabolic risk. Therapeutic perspectives include diet recommendations regarding hydration, but also potential pharmacological interventions targeting the VP V1aR.
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