Melatonin suppresses NO-induced apoptosis via induction of Bcl-2 expression in PGT-beta immortalized pineal cells.
In the present study, we investigated whether melatonin would prevent nitric oxide (NO)-induced apoptotic death of PGT-beta immortalized pineal cells. To examine the protective effect of melatonin, cytotoxicity assay, DNA fragmentation analysis, caspase-3 activity assay, and Western blotting for caspase-3 and poly(ADP-ribose) polymerase (PARP) were performed. Treatment of cells with S-nitroso-N-acetylpenicillamine (SNAP), an NO donor, was shown to induce apoptotic cell death in a dose-dependent manner, and pretreatment with melatonin (0.1 mm) attenuated the occurrence of NO-induced apoptotic cell death. DNA fragmentation in response to NO was also arrested by melatonin. Caspase-3 activity induced by NO was decreased with melatonin treatment. Furthermore, the active fragments of caspase-3 and PARP were almost completely absent following exposure to melatonin. To elucidate the protective mechanisms of action of melatonin, Western blot analyses for Bcl-2 expression and cytochrome c release were carried out. Pretreatment with melatonin (0.1 mm) induced the expression of Bcl-2 and suppressed the release of cytochrome c into the cytosol, thereby arresting NO-induced apoptotic cell death. These results suggest that the antiapoptotic effect of melatonin is associated with induction of Bcl-2 expression in PGT-beta cells, which in turn blocks caspase-3 activation and inhibits cytochrome c release into the cytosol.[1]References
- Melatonin suppresses NO-induced apoptosis via induction of Bcl-2 expression in PGT-beta immortalized pineal cells. Yoo, Y.M., Yim, S.V., Kim, S.S., Jang, H.Y., Lea, H.Z., Hwang, G.C., Kim, J.W., Kim, S.A., Lee, H.J., Kim, C.J., Chung, J.H., Leem, K.H. J. Pineal Res. (2002) [Pubmed]
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