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International Journal of Endocrinology
Volume 2012 (2012), Article ID 549081, 7 pages
http://dx.doi.org/10.1155/2012/549081
Research Article

Exendin-4 Protects MIN6 Cells from t-BHP-Induced Apoptosis via IRE1-JNK-Caspase-3 Signaling

Department of Endocrinology, Fujian Institute of Endocrinology, Union Hospital of Fujian Medical University, Fuzhou, Fujian 350001, China

Received 19 September 2011; Accepted 28 December 2011

Academic Editor: Stephen L. Atkin

Copyright © 2012 Wen-Jia Chen et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Objectives. This study aimed to explore the effect of exendin-4 on t-BHP-induced apoptosis in pancreatic β cells and the mechanism of action. Methods. Murine MIN6 pancreatic β cells were treated with exendin-4 in the presence or absence of tert-butyl hydroperoxide (t-BHP). Cell survival was assessed by MTT staining. The percentage of apoptotic cells was determined by fluorescence microscopy analysis after Hoechst/PI staining and flow cytometric assay after Annexin V-FITC/PI staining. The activity of caspase-3 was determined using a caspase-3 activity kit. Expression of P-IRE1α, IRE1α, C-Jun N-terminal kinase (JNK), P-JNK, C-JUN, and P-C-JUN was detected by western blotting. Results. Exendin-4 was found to inhibit t-BHP-induced apoptosis in pancreatic β-cells by downregulating caspase-3 activity. Exendin-4 also inhibited the endoplasmic reticulum transmembrane protein IRE1, the apoptosis-related signaling molecule JNK, and c-Jun activation. Conclusions. Our findings suggest that exendin-4 ultimately reduces t-BHP-induced β-cell apoptosis. IRE1-JNK-c-Jun signaling is involved in the exendin-4-mediated modulation of β-cell apoptosis.