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Pituitary adenylate cyclase-activating polypeptide attenuates streptozotocin-induced apoptotic death of RIN-m5F cells through regulation of Bcl-2 family protein mRNA expression
- Onoue, Satomi, Hanato, Junko, Yamada, Shizuo
- FEBS journal 2008 v.275 no.22 pp. 5542-5551
- antioxidants, apoptosis, caspase-3, cytotoxicity, gene expression, gene expression regulation, lactate dehydrogenase, messenger RNA, neuropeptides, noninsulin-dependent diabetes mellitus, oxidative stress, polypeptides, rats, reverse transcriptase polymerase chain reaction, streptozotocin
- Oxidative stress, followed by the apoptotic death of pancreatic β cells, is considered to be one of causative agents in the evolution of the type 2 diabetic state; therefore, the protection of β cells can comprise an efficacious strategy for preventing type 2 diabetes. In the present study, RIN-m5F cells (i.e. the rat insulinoma β cell line) were stimulated with streptozotocin, resulting in a time- and concentration-dependent release of lactate dehydrogenase. There appeared to be significant apoptotic cell death after 2 h of treatment with streptozotocin at 10 m m, as demonstrated by terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling staining and 2.6-fold activation of cellular caspase-3, an apoptotic enzyme. By contrast, some neuropeptides of the glucagon-secretin family and coenzyme Q₁₀, an endogenous mitochondrial antioxidant, could attenuate streptozotocin cytotoxicity, and especially pituitary adenylate cyclase-activating polypeptide (PACAP), at a concentration of 10⁻⁷ m, exhibited 34% attenuation of lactate dehydrogenase release from streptozotocin-treated RIN-m5F cells. Quantitative RT-PCR experiments indicated the inhibitory effect of PACAP on streptozotocin-evoked up-regulation of pro-apoptotic factor (Noxa and Bax) and a 2.3-fold enhancement of Bcl-2 mRNA expression, a pro-survival protein, was also observed after addition of PACAP. The data obtained suggest the anti-apoptotic role of PACAP in streptozotocin-treated RIN-m5F cells through the regulation of pro-apoptotic and pro-survival factors.