热休克蛋白对短暂心肌缺血所致蛋白质聚集的影响

Effects of Heat Shock Proteins on Protein Aggregation Induced by Transient Myocardial Ischemia

为了观察短暂心肌缺血后心肌中蛋白质聚集物的产生 ,探讨热休克蛋白 70及αB 晶状体蛋白对心肌中蛋白质聚集物的影响 ,采用雄性Wistar大鼠制备在体心缺血—再灌注损伤模型 ,通过乙醇磷钨酸电镜观察蛋白质聚集物产生 ,采用免疫电镜观察热休克蛋白 70及αB 晶状体蛋白对蛋白质聚集物的影响。结果发现 :①缺血 15min再灌注 30min时 ,心肌细胞中开始出现形态不规则的蛋白质聚集物 ,聚集物主要分布在核周、线粒体周围及其两极。再灌注 4h ,蛋白质聚集物达到高峰 ,2 4h后逐渐减少 ,72h基本恢复正常。②大鼠经热休克预处理及缺血预适应后 ,15min缺血及 4h或 2 4h再灌注所致的心肌蛋白质聚集物的产生明显减少 ,恢复速度加快 ,再灌注 2 4h已基本恢复正常。③通过免疫电镜观察 ,在假手术对照组 ,心肌中热休克蛋白 70表达水平很低。大鼠经热休克预处理后 ,心肌中热休克蛋白 70表达增多 ,经缺血 15min再灌注 4h后 ,热休克蛋白 70与心肌中蛋白质聚集物共分布。在假手术对照组心肌中 ,αB 晶状体蛋白有一定量的组成型表达 ,并均匀分布于胞浆之中。经热休克预处理、缺血预适应后缺血 15min再灌注 4h心肌中 ,αB 晶状体蛋白向肌丝移位 ,主要位于Z线两侧的明带 ,且与蛋白质聚集物共分布。本研究首次揭示了缺血—再灌注损?

Aim To investigate whether transient myocardial ischemia might cause protein aggregation, and to observe whether heat shock pretreatment and ischemic preconditioning could alleviate protein aggregation. Methods Myocardial ischemial-reperfusion injury model was prepared by ligation of left descending anterior coronary artery for 15 minutes then released for various durations in rats. Protein aggregates induced by ischemia-reperfusion injury in cardiomyocytes were observed by using ethanolic phosphotungstic acid (EPTA) electron microscopy (EM). The influence of heat shock protein 70 (HSP70) and αB-crystallin on above protein damage was further investigated by immunoelectron microscopy. Results ①Myocardial ischemia-reperfusion resulted in protein aggregation, which appeared at 30 min of reperfusion, peaked at 4 h of reperfusion, decreased from 24 h of reperfusion and restored to normal at 72 h of reperfusion after 15 min of ischemia. ②Heat shock pretreatment (rectal temperature 42℃ for 15 min then recovery for 24 h) and ischemic preconditioning (ischemia for 3 min then reperfusion for 10 min ) significantly decreased myocardial protein aggregates induced by 15 min of ischemia and 4 h of reperfusion and facilitated the restoration of myocardial protein damage. ③HSPs played key roles in the myocardial protection of heat shock pretreatment and ischemic preconditioning. In the present study, we found that HSP70 and αB-cystallin co-localized with protein aggregates in heat shock pretreatment and ischemic preconditioning groups. Conclusion This study, for the first time, demonstrated the formation, intracellular distribution and dynamic patterns of myocardial protein aggregates induced by ischemia-reperfusion injury, and found that heat shock pretreatment and ischemic preconditioning alleviated the formation of myocardial protein aggregates.