title: Phosphorylation of caveolin-1 on tyrosine-14 induced by ROS enhances palmitate-induced death of beta-pancreatic cells.
abstract: A considerable body of evidence exists implicating high levels of free saturated fatty acids in beta pancreatic cell death, although the molecular mechanisms and the signaling pathways involved have not been clearly defined. The membrane protein caveolin-1 has long been implicated in cell death, either by sensitizing to or directly inducing apoptosis and it is normally expressed in beta cells. Here, we tested whether the presence of caveolin-1 modulates free fatty acid-induced beta cell death by reexpressing this protein in MIN6 murine beta cells lacking caveolin-1. Incubation of MIN6 with palmitate, but not oleate, induced apoptotic cell death that was enhanced by the presence of caveolin-1. Moreover, palmitate induced de novo ceramide synthesis, loss of mitochondrial transmembrane potential and reactive oxygen species (ROS) formation in MIN6 cells. ROS generation promoted caveolin-1 phosphorylation on tyrosine-14 that was abrogated by the anti-oxidant N-acetylcysteine or the incubation with the Src-family kinase inhibitor, PP2 (4-amino-5-(4-chlorophenyl)-7(dimethylethyl)pyrazolo[3,4-d]pyrimidine). The expression of a non-phosphorylatable caveolin-1 tyrosine-14 to phenylalanine mutant failed to enhance palmitate-induced apoptosis while for MIN6 cells expressing the phospho-mimetic tyrosine-14 to glutamic acid mutant caveolin-1 palmitate sensitivity was comparable to that observed for MIN6 cells expressing wild type caveolin-1. Thus, caveolin-1 expression promotes palmitate-induced ROS-dependent apoptosis in MIN6 cells in a manner requiring Src family kinase mediated tyrosine-14 phosphorylation.
authors.affiliation: Laboratory of Cellular Communication, Center for Molecular Studies of the Cell (CEMC), Advanced Center for Chronic Diseases (ACCDiS), Faculty of Medicine, Universidad de Chile, Santiago de Chile, Chile; Research Program of Interdisciplinary Excellence in Healthy Aging (PIEI-ES), Faculty of Health Sciences, Department of Clinical Biochemistry and Immunohematology, Universidad de Talca, 3465548 Talca, Chile.
authors.forename: Sergio
authors.initials: S
authors.lastname: Wehinger
authors.affiliation: Laboratory of Cellular Communication, Center for Molecular Studies of the Cell (CEMC), Advanced Center for Chronic Diseases (ACCDiS), Faculty of Medicine, Universidad de Chile, Santiago de Chile, Chile.
authors.forename: Rina
authors.initials: R
authors.lastname: Ortiz
authors.affiliation: Laboratory of Cellular Communication, Center for Molecular Studies of the Cell (CEMC), Advanced Center for Chronic Diseases (ACCDiS), Faculty of Medicine, Universidad de Chile, Santiago de Chile, Chile.
authors.forename: María Inés
authors.initials: MI
authors.lastname: Díaz
authors.affiliation: Laboratory of Cellular Communication, Center for Molecular Studies of the Cell (CEMC), Advanced Center for Chronic Diseases (ACCDiS), Faculty of Medicine, Universidad de Chile, Santiago de Chile, Chile.
authors.forename: Adam
authors.initials: A
authors.lastname: Aguirre
authors.affiliation: Laboratory of Cellular Communication, Center for Molecular Studies of the Cell (CEMC), Advanced Center for Chronic Diseases (ACCDiS), Faculty of Medicine, Universidad de Chile, Santiago de Chile, Chile.
authors.forename: Manuel
authors.initials: M
authors.lastname: Valenzuela
authors.affiliation: Institute for Research in Dental Sciences, Facultad de Odontología, Universidad de Chile, Santiago, Chile.
authors.forename: Paola
authors.initials: P
authors.lastname: Llanos
authors.affiliation: Departament of Pediatrics, Atlantic Research Centre, Dalhousie University, Halifax, NS, Canada; Department of Biochemistry and Molecular Biology, Atlantic Research Centre, Dalhousie University, Halifax, NS, Canada.
authors.forename: Christopher
authors.initials: C
authors.lastname: Mc Master
authors.affiliation: Laboratory of Cellular Communication, Center for Molecular Studies of the Cell (CEMC), Advanced Center for Chronic Diseases (ACCDiS), Faculty of Medicine, Universidad de Chile, Santiago de Chile, Chile.
authors.forename: Lisette
authors.initials: L
authors.lastname: Leyton
authors.affiliation: Laboratory of Cellular Communication, Center for Molecular Studies of the Cell (CEMC), Advanced Center for Chronic Diseases (ACCDiS), Faculty of Medicine, Universidad de Chile, Santiago de Chile, Chile. Electronic address: aquest@med.uchile.cl.
authors.forename: Andrew F G
authors.initials: AF
authors.lastname: Quest
mesh_terms: D000111:Acetylcysteine / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D051242:Caveolin 1 / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D016166:Free Radical Scavengers / Q000494:pharmacology; D006861:Hydrogen Peroxide / Q000494:pharmacology; D050417:Insulin-Secreting Cells / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D008810:Mice, Inbred C57BL; D018613:Microscopy, Confocal; D016877:Oxidants / Q000494:pharmacology; D010168:Palmitates / Q000494:pharmacology*; D010766:Phosphorylation / Q000187:drug effects; D011743:Pyrimidines / Q000494:pharmacology; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013110:Sphingosine / Q000031:analogs & derivatives / Q000494:pharmacology; D014443:Tyrosine / Q000378:metabolism; D019061:src-Family Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: C412373:AG 1879; D051242:Caveolin 1; D016166:Free Radical Scavengers; C064769:N-acetylsphingosine; D016877:Oxidants; D010168:Palmitates; D011743:Pyrimidines; D017382:Reactive Oxygen Species; D014443:Tyrosine; D006861:Hydrogen Peroxide; D019061:src-Family Kinases; D013110:Sphingosine; D000111:Acetylcysteine
keywords: Apoptosis; Beta cell; Caveolin-1; Palmitate; Reactive oxygen species; Tyrosine-14