[Heat shock pretreatment inhibits the release of Smac from mitochondria and decreases H2O2-induced cardiomyocyte apoptosis].
OBJECTIVE
To explore the effect of heat shock pretreatment on H2O2-induced apoptosis of neonatal rat cardiomyocytes and the release of Smac from mitochondria.


METHODS
After heat shock pretreatment (42 degrees C for 1 h), neonatal cardiomyocytes were exposed to H2O2 (0.5 mmol/L) for 6, 12, 24, and 36 h, respectively. The apoptotic morphological changes and percentage of apoptotic nuclei were analyzed. Activities of caspase-3, 9 were assayed with caspase colorimetric assay kit and Western-blotting. Inducible heat shock proteins were detected by Western-blotting analysis. The release of Smac from mitochondria to cytoplasm was observed by Western-blotting and immunofluorescence.


RESULTS
(1) H2O2 (0.5 mmol/L) resulted in a marked release of Smac from mitochondria to cytoplasm at 2 h after the treatment, the activation of caspase-9 and caspase-3 at 4 h after the treatment and specific morphological changes of apoptosis at 24 h after the treatment. (2) Heat shock pretreatment (42 degrees C, 1 h) could increase the expression of hsp90, hsp70 and betaB-crystallin, and inhibit the H2O2-induced release of Smac from mitochondria, the activity of caspase-9, caspase-3 and apoptosis of cardiomyocytes.


CONCLUSIONS
(1) Mitochondrial signal transduction pathway is involved in the apoptosis of cardiomyocytes induced by H2O2; (2) Heat shock pretreatment can inhibit the release of Smac from mitochondria and the activities of caspase-9, 3 and protect cardiomyocytes against H2O2-induced apoptosis.
Jiang
Bi-mei
BM
Department of Pathophysiology, Xiangya School of Medicine, Central South University, Changsha 410078, China.
Xiao
Wei-min
WM
Shi
Yong-zhong
YZ
D000818:Animals; D000831:Animals, Newborn; D017209:Apoptosis / Q000187:drug effects*; D051017:Apoptosis Regulatory Proteins; D002478:Cells, Cultured; D006360:Heat-Shock Proteins / Q000096:biosynthesis; D018869:Heat-Shock Response; D006861:Hydrogen Peroxide / Q000494:pharmacology; D047908:Intracellular Signaling Peptides and Proteins; D008929:Mitochondria, Heart / Q000378:metabolism*; D024101:Mitochondrial Proteins / Q000096:biosynthesis*; D032383:Myocytes, Cardiac / Q000166:cytology* / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000096:biosynthesis; D051381:Rats; D017208:Rats, Wistar
D051017:Apoptosis Regulatory Proteins; C412403:DIABLO protein, human; D006360:Heat-Shock Proteins; D047908:Intracellular Signaling Peptides and Proteins; D024101:Mitochondrial Proteins; D006861:Hydrogen Peroxide; D052247:Nitric Oxide Synthase Type II