DJ-1蛋白耦联热休克蛋白60在缺血性心肌损伤中的作用及机制研究。

Identification and restoration of ischaemia/hypoxia-induced myocardial injuries at the early stage has increasingly brought into sight nowadays. Our previous study found that heat shock protein 60(HSP60) ，a chaperon protein, was released during the first hour after the onset of myocardial ischaemia. The released HSP60 led to myocardial injuries through Toll-like receptor-4 signaling pathway. However, blocking the released extracellular HSP60 was not sufficient to protect the heart against injuries. Recently, it has been reported that the expression level of intracellular DJ-1 protein was decreased significantly during the first hour after myocardial ischaemia. And over-expression of DJ-1 could increase cell viability against hypoxia-induced injuries. Physiologically, DJ-1 protein protects cells against apoptosis as a dimer with the help of chaperon proteins. Under oxidative stress, the dysfunction of DJ-1 resulted in cellular injuries but the expression of chaperon proteins could restore the injuries. Our hypothesis is that the decreased intracellular HSP60 lead to dysfunction of DJ-1 protein, which in turn causes myocardial injuries, after the trigger of myocardial ischaemia and hypoxia. This study is designed to explore the interaction of DJ-1 and HSP60 in myocardial ischaemia/hypoxia-induced injuries, thus provides a new insight into clinical therapy based on "Early intervention, timely protection of heart" strategy.

早期发现心肌缺血缺氧性损伤并修复受损心肌日益受到人们的关注。申请者前期研究证实，心肌发生缺血缺氧性损伤1h内，释放出分子伴侣蛋白：热休克蛋白60（HSP60）；胞外HSP60经心肌细胞膜上Toll样受体4传递信号引起心肌细胞损伤。然而阻断胞外HSP60并不能完全有效减少心肌损伤。有研究发现：心肌缺血1h内，胞内DJ-1蛋白质水平显著下降；过表达DJ-1可提高低氧损伤后细胞生存率。DJ-1蛋白在分子伴侣蛋白参与下以二聚体形式存在并保护细胞对抗凋亡。氧化应激时DJ-1蛋白失活造成细胞损伤，分子伴侣蛋白的表达可逆转这一现象。我们假设：心肌短期缺血缺氧性损伤后，胞内热休克蛋白60减少使DJ-1蛋白功能障碍，从而参与HSP60介导的心肌细胞损伤。本项目旨在探讨心肌细胞内DJ-1与HSP60的相互作用，及其在缺血缺氧性心肌损伤中的作用，为"早期干预、及时保护心肌细胞"的治疗策略提供理论基础和实验依据。

本项目探索了DJ-1蛋白在心肌缺血时早期心肌损伤中的作用及可能的分子机制。本项目研究发现心肌细胞缺血后DJ-1蛋白细胞内表达显著下降，而恢复DJ-1蛋白表达可保护心肌细胞对抗急性缺血时细胞死亡；DJ-1蛋白的心肌保护功能可能通过阻止线粒体功能障碍实现。和对照组相比，过表达DJ-1的心肌细胞在急性心肌缺血时可延迟线粒体通透性转换孔（MPTP）开放与线粒体延长感应。在细胞中表达的非功能性DJ-1突变体后失去急性心肌缺血时心肌保护能力。因此，我们证明DJ-1保护急性心肌缺血部分通过阻止线粒体功能障碍而实现。我们因此推论：DJ-1可能可作为心肌缺血时心肌细胞保护的新治疗靶点。除此之外，本项目还初步探索了DJ-1蛋白、先天性免疫系统及microRNA在肿瘤中的作用和可能的分子机制。研究主要从以下几个方面进行：（1）初步探索了DJ-1蛋白在乳腺癌中的表达定位及其与临床病理因素、预后的关系；（2）先天性免疫系统Toll样受体4（TLR4）配体信号分子HMGB1在非小细胞肺癌化疗中的作用及可能的机制；（3）microRNA中MiR-363在乳腺癌化疗中的作用及可能的分子机制。