| First Author | Souza JC | Year | 2013 |
| Journal | Biochim Biophys Acta | Volume | 1831 |
| Issue | 4 | Pages | 769-75 |
| PubMed ID | 23298460 | Mgi Jnum | J:199048 |
| Mgi Id | MGI:5500146 | Doi | 10.1016/j.bbalip.2012.12.013 |
| Citation | Souza JC, et al. (2013) Cholesterol reduction ameliorates glucose-induced calcium handling and insulin secretion in islets from low-density lipoprotein receptor knockout mice. Biochim Biophys Acta 1831(4):769-75 |
| abstractText | AIMS/HYPOTHESIS: Changes in cellular cholesterol level may contribute to beta cell dysfunction. Islets from low density lipoprotein receptor knockout (LDLR(-/-)) mice have higher cholesterol content and secrete less insulin than wild-type (WT) mice. Here, we investigated the association between cholesterol content, insulin secretion and Ca(2+) handling in these islets. METHODS: Isolated islets from both LDLR(-/-) and WT mice were used for measurements of insulin secretion (radioimmunoassay), cholesterol content (fluorimetric assay), cytosolic Ca(2+) level (fura-2AM) and SNARE protein expression (VAMP-2, SNAP-25 and syntaxin-1A). Cholesterol was depleted by incubating the islets with increasing concentrations (0-10mmol/l) of methyl-beta-cyclodextrin (MbetaCD). RESULTS: The first and second phases of glucose-stimulated insulin secretion (GSIS) were lower in LDLR(-/-) than in WT islets, paralleled by an impairment of Ca(2+) handling in the former. SNAP-25 and VAMP-2, but not syntaxin-1A, were reduced in LDLR(-/-) compared with WT islets. Removal of excess cholesterol from LDLR(-/-) islets normalized glucose- and tolbutamide-induced insulin release. Glucose-stimulated Ca(2+) handling was also normalized in cholesterol-depleted LDLR(-/-) islets. Cholesterol removal from WT islets by 0.1 and 1.0mmol/l MbetaCD impaired both GSIS and Ca(2+) handling. In addition, at 10mmol/l MbetaCD WT islet showed a loss of membrane integrity and higher DNA fragmentation. CONCLUSION: Abnormally high (LDLR(-/-) islets) or low cholesterol content (WT islets treated with MbetaCD) alters both GSIS and Ca(2+) handling. Normalization of cholesterol improves Ca(2+) handling and insulin secretion in LDLR(-/-) islets. |
