Buriro R, Lv Y J, Ali I, Tang S, Liu Z J, Zhang M, Adem A, Hartung J, Bao E D
College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.
Genet Mol Res. 2013 Aug 20;12(3):3003-16. doi: 10.4238/2013.August.20.2.
The mechanisms involved in sudden animal death due to acute heart failure during heat stress are not well understood. We examined the relationship between heat stress-induced variations of protective Hsp60 and expression of its regulatory factor, HSF-1, in heat-stressed primary myocardial cells of neonatal rats in vitro through cardiac enzyme detection, immunoblotting, immunocytochemistry, and qPCR. Increases in cardiac damage-related enzyme levels demonstrated injury to myocardial cells after heat exposure at 42°C. Hsp60 expression levels fluctuated during heat stress; they decreased significantly after 20 min, then increased at 120 min and decreased again at 360 min after initiation of heat stress. The highest levels of Hsp60 were observed at 240 min, while the lowest were at 60 min. Damage to myocardial cells was characterized by increases in cardiac enzyme levels and low levels of Hsp60 due to functional disorder of myocardial cells at early stages of heat stress. However, the significant induction of hsp60 mRNA levels from the beginning up to 240 min of heat stress was not consistent with the classic regulatory mechanisms that link transcription and translation, suggesting that Hsp60 expression is delayed due to loss of Hsp60 during the early stages of heat stress. hsf-1 mRNA levels were significantly increased from 10 min of heat stress; however, HSF-1 protein levels did not simultaneously increase, indicating that HSF-1 is not the sole regulator of Hsp60 expression.
热应激期间急性心力衰竭导致动物猝死的相关机制尚未完全明确。我们通过检测心肌酶、免疫印迹、免疫细胞化学和定量聚合酶链反应，研究了体外热应激新生大鼠原代心肌细胞中热应激诱导的保护性热休克蛋白60（Hsp60）变化与其调节因子热休克因子1（HSF-1）表达之间的关系。心脏损伤相关酶水平升高表明42℃热暴露后心肌细胞受到损伤。热应激期间Hsp60表达水平波动；热应激开始后20分钟显著下降，然后在120分钟时升高，360分钟时再次下降。Hsp60在240分钟时达到最高水平，在60分钟时最低。热应激早期心肌细胞功能紊乱导致心肌细胞损伤的特征是心脏酶水平升高和Hsp60水平降低。然而，热应激开始至240分钟期间hsp60 mRNA水平的显著诱导与连接转录和翻译的经典调节机制不一致，这表明热应激早期Hsp60表达延迟是由于Hsp60丢失所致。热应激10分钟起hsf-1 mRNA水平显著升高；然而，HSF-1蛋白水平并未同时升高，这表明HSF-1不是Hsp60表达的唯一调节因子。
