Cholesterol reduction ameliorates glucose-induced calcium handling and insulin secretion in islets from low-density lipoprotein receptor, knockout mice

Cholesterol reduction ameliorates glucose-induced calcium handling and insulin secretion in islets from low-density lipoprotein receptor, knockout mice

Author Souza, J. C. Google Scholar
Vanzela, E. C. Google Scholar
Ribeiro, R. A. Google Scholar
Rezende, L. F. Google Scholar
Oliveira, C. A. de Autor UNIFESP Google Scholar
Carneiro, E. M. Google Scholar
Oliveira, H. C. F. Google Scholar
Boschero, A. C. Google Scholar
Institution Universidade Estadual de Campinas (UNICAMP)
Universidade Federal de São Paulo (UNIFESP)
Abstract 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 Ca2+ 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 Ca2+ level (fura-2AM) and SNARE protein expression (VAMP-2, SNAP-25 and syntaxin-1A). Cholesterol was depleted by incubating the islets with increasing concentrations (0-10 mmol/l) of methyl-beta-cyclodextrin (M beta CD).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 Ca2+ 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 Ca2+ handling was also normalized in cholesterol-depleted LDLR-/- islets. Cholesterol removal from WT islets by 0.1 and 1.0 mmol/l M beta CD impaired both GSIS and Ca2+ handling. in addition, at 10 mmol/l M beta CD 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 M beta CD) alters both GSIS and Ca2+ handling. Normalization of cholesterol improves Ca2+ handling and insulin secretion in LDLR-/- islets. (C) 2013 Elsevier B.V. All rights reserved.
Keywords Calcium handling
Insulin secretion
LDLR-/- mice
SNARE proteins
Language English
Sponsor Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
Instituto Nacional de Ciencia e Tecnologia de Obesidade e Diabetes
Date 2013-04-01
Published in Biochimica Et Biophysica Acta-molecular and Cell Biology of Lipids. Amsterdam: Elsevier B.V., v. 1831, n. 4, p. 769-775, 2013.
ISSN 1388-1981 (Sherpa/Romeo, impact factor)
Publisher Elsevier B.V.
Extent 769-775
Access rights Closed access
Type Article
Web of Science ID WOS:000316438200011

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