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.
Yoo
Yeong-Min
YM
Department of Biology, College of Natural Science, Kangwon National University, Chunchon, South Korea.
Yim
Sung-Vin
SV
Kim
Sung-Soo
SS
Jang
Hyun Yong
HY
Lea
Ho Zoo
HZ
Hwang
Geun-Cheal
GC
Kim
Jong-Woo
JW
Kim
Soon-Ae
SA
Lee
Hee Jae
HJ
Kim
Chang-Ju
CJ
Chung
Joo-Ho
JH
Leem
Kang-Hyun
KH
D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D002460:Cell Line; D003574:Cytochrome c Group / Q000378:metabolism; D053938:DNA Fragmentation / Q000187:drug effects; D008550:Melatonin / Q000494:pharmacology*; D051379:Mice; D020030:Nitric Oxide Donors / Q000494:pharmacology*; D010870:Pineal Gland / Q000166:cytology* / Q000187:drug effects* / Q000378:metabolism; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis*; D026423:S-Nitroso-N-Acetylpenicillamine / Q000494:pharmacology
D003574:Cytochrome c Group; D020030:Nitric Oxide Donors; D019253:Proto-Oncogene Proteins c-bcl-2; D026423:S-Nitroso-N-Acetylpenicillamine; D011065:Poly(ADP-ribose) Polymerases; C505409:Casp3 protein, mouse; D053148:Caspase 3; D020169:Caspases; D008550:Melatonin