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- Zhou, Yunting, et al.
(author)
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Lipotoxicity reduces beta cell survival through islet stellate cell activation regulated by lipid metabolism-related molecules
- 2019
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In: Experimental Cell Research. - : ELSEVIER INC. - 0014-4827 .- 1090-2422. ; 380:1, s. 1-8
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Journal article (peer-reviewed)abstract
- Background: Islet stellate cells (ISCs) activation is mainly associated with islet fibrosis, which contributes to the progression of type 2 diabetes. However, the molecular mechanism underlying this process is not fully understood.Methods: In order to investigate this process the current study examined ectopic fat accumulation in rats with high-fat diet (HFD) induced obesity. Levels of lipotoxicity-induced ISC activation and islet function were assessed via intraperitoneal glucose and insulin tolerance tests, and immunohistochemistry. The expression of lipid metabolism- and ISC activation-related markers was evaluated in cultured ISCs treated with palmitic acid (PA) using quantitative PCR and western blotting. We also overexpressed sterol regulatory element-binding protein (SREBP)-1c in ISCs by lentiviral transduction, and assessed the effects on insulin release in co-cultures with isolated rat islets.Results: HFD increased body weight and ectopic fat accumulation in pancreatic islets. Lipotoxicity caused progressive glucose intolerance and insulin resistance, upregulated a-smooth muscle actin, and stimulated the secretion of extracellular matrix. Lipotoxicity reduced the expression of lipid metabolism-related molecules in ISCs treated with PA, especially SREBP-1c. Overexpression of SREBP-1c in ISCs improved islet viability and insulin secretion in co-cultures.Conclucions: These results indicate that lipotoxicity-induced ISC activation alters islet function via regulation of lipid metabolism, suggesting that therapeutic strategies targeting activated ISC may be an effective treatment for prevention of ISC activation-associated islet dysfunction.
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