Involvement of calcium-mediated apoptotic signals in H2O2-induced MIN6N8a cell death

• Published in: European journal of pharmacology 2006-10, Vol.547 (1-3), p.1
• Main Authors: Choi, Sung-E, Min, Se-Hee, Shin, Ha-Chul, Kim, Hyo-Eun, Jung, Min Whan, Kang, Yup
• Format: Article
• Language: English
• Subjects: Animals; Apoptosis - drug effects; Calcineurin - metabolism; Calcineurin Inhibitors; Calcium - antagonists & inhibitors; Calcium - metabolism; Calpain - antagonists & inhibitors; Calpain - metabolism; Caspase 3 - metabolism; Cell Line, Tumor; Cell Survival - drug effects; Chelating Agents - pharmacology; Dose-Response Relationship, Drug; Egtazic Acid - analogs & derivatives; Egtazic Acid - pharmacology; Enzyme Activation - drug effects; Enzyme Inhibitors - pharmacology; Hydrogen Peroxide - toxicity; Insulinoma - metabolism; Insulinoma - pathology; Intracellular Fluid - drug effects; Intracellular Fluid - metabolism; JNK Mitogen-Activated Protein Kinases - metabolism; Macrocyclic Compounds - pharmacology; Oxazoles - pharmacology; Oxidants - toxicity; Poly(ADP-ribose) Polymerases - metabolism; Ryanodine - pharmacology; Signal Transduction - drug effects
• ISSN: 0014-2999
• DOI: 10.1016/j.ejphar.2006.06.016

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.