title: Involvement of calcium-mediated apoptotic signals in H2O2-induced MIN6N8a cell death.
abstract: Reactive oxygen species are believed to be the central mediators of beta-cell destruction that leads to type 1 and 2 diabetes, and calcium has been reported to be an important mediator of beta cell death. In the present study, the authors investigated whether Ca(2+) plays a role in hydrogen peroxide (H(2)O(2))-induced MIN6N8a mouse beta cell death. Treatment with low concentration H(2)O(2) (50 microM) was found to be sufficient to reduce MIN6N8a cell viability by 55%, largely via apoptosis. However, this H(2)O(2)-induced cell death was near completely blocked by pretreatment with BAPTA/AM (5 microM), a chelator of intracellular Ca(2+). Moreover, the intracellular calcium store channel blockers, such as, xestospongin c and ryanodine, significant protected cells from 50 microM H(2)O(2)-induced cell death and under extracellular Ca(2+)-free conditions, 50 microM H(2)O(2) elicited transient [Ca(2+)](i) increases. In addition, pharmacologic inhibitors of calpain, calcineurin, and calcium/calmodulin-dependent protein kinase II were found to have a protective effect on H(2)O(2)-induced death. Moreover, H(2)O(2)-induced apoptotic signals, such as c-JUN N-terminal kinase activation, cytochrome c release, caspase 3 activation, and poly (ADP-ribose) polymerase cleavage were all down-regulated by the intracellular Ca(2+) chelation. These findings show that [Ca(2+)](i) elevation, possibly due to release from intracellular calcium stores and the subsequent activation of Ca(2+)-mediated apoptotic signals, critically mediates low concentration H(2)O(2)-induced MIN6N8a cell death. These findings suggest that a breakdown of calcium homeostasis by low level of reactive oxygen species may be involved in beta cell destruction during diabetes development.
authors.affiliation: Institute for Medical Science, Ajou University School of Medicine,442-749, Suwon, Kyunggi-do, Republic of Korea.
authors.forename: Sung-E
authors.initials: SE
authors.lastname: Choi
authors.forename: Se-Hee
authors.initials: SH
authors.lastname: Min
authors.forename: Ha-Chul
authors.initials: HC
authors.lastname: Shin
authors.forename: Hyo-Eun
authors.initials: HE
authors.lastname: Kim
authors.forename: Min Whan
authors.initials: MW
authors.lastname: Jung
authors.forename: Yup
authors.initials: Y
authors.lastname: Kang
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D019703:Calcineurin / Q000378:metabolism; D065095:Calcineurin Inhibitors; D002118:Calcium / Q000037:antagonists & inhibitors / Q000378:metabolism*; D002154:Calpain / Q000037:antagonists & inhibitors / Q000378:metabolism; D053148:Caspase 3 / Q000378:metabolism; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D002614:Chelating Agents / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006861:Hydrogen Peroxide / Q000633:toxicity*; D007340:Insulinoma / Q000378:metabolism / Q000473:pathology; D007424:Intracellular Fluid / Q000187:drug effects / Q000378:metabolism; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D047028:Macrocyclic Compounds / Q000494:pharmacology; D010080:Oxazoles / Q000494:pharmacology; D016877:Oxidants / Q000633:toxicity; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D012433:Ryanodine / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects*
chemical_list: D065095:Calcineurin Inhibitors; D002614:Chelating Agents; D004791:Enzyme Inhibitors; D047028:Macrocyclic Compounds; D010080:Oxazoles; D016877:Oxidants; C511704:xestospongin C; C070379:1,2-bis(2-aminophenoxy)ethane N,N,N',N'-tetraacetic acid acetoxymethyl ester; D012433:Ryanodine; D004533:Egtazic Acid; D006861:Hydrogen Peroxide; D011065:Poly(ADP-ribose) Polymerases; D048031:JNK Mitogen-Activated Protein Kinases; D019703:Calcineurin; D002154:Calpain; D053148:Caspase 3; D002118:Calcium