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- Zhou, Yunting, et al.
(författare)
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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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Ingår i: Experimental Cell Research. - : ELSEVIER INC. - 0014-4827 .- 1090-2422. ; 380:1, s. 1-8
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Tidskriftsartikel (refereegranskat)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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| 2. |
- Li, Wei, et al.
(författare)
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A modified in vitro tool for isolation and characterization of rat quiescent islet stellate cells
- 2019
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Ingår i: Experimental Cell Research. - : ELSEVIER INC. - 0014-4827 .- 1090-2422. ; 384:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: Islet stellate cells (ISCs) play a critical role in islet fibrosis, contributing to the progression of pancreatic diseases. Previous studies have focused on fibrosis-associated activated ISCs obtained by standard islet explant techniques. However, in vitro models of quiescent ISCs (qISCs) are lacking. This study aims to develop a method to isolate qISCs and analyze their phenotype during activation.Methods: Immunofluorescence staining was applied to localize ISCs in normal human, rat, and mouse islets. qISCs were isolated from rat islets using density gradient centrifugation (DGC) method. qRT-PCR, immunoblotting, proliferation, and migration assays were employed for their characterization.Results: Desmin-positive ISCs were detected in normal human, rat, and mouse islets. Freshly isolated qISCs, obtained by density gradient centrifugation, displayed a polygonal appearance with refringent cytoplasmic lipid droplets and expressed transcriptional markers indicating a low activation/quiescent state. With increasing culture time, the marker expression pattern changed, reflecting ISC activation. qISCs contained more lipid droplets and exhibited lower proliferation and migration abilities compared to spindle-shaped ISCs obtained by traditional explant techniques.Conclusions: This study describes a new method for efficient isolation of qISCs from rat islets, representing a useful in vitro tool to study the biology of ISCs in more physiological conditions.
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