Pyk2/MCU通路在缺血性脑卒中的作用及机制

Brain ischemia stroke is a common disease in neurology with high morbidity and mortality. Although the ultra-early thrombolytic treatment is effective, but receiving treatment within a specified time window is difficult for most patients. Further research is needed to contribute to inhibit neuron damage and improve neurological function. One of the key mechanism after ischemia is calcium overload caused by calcium influx, which causing mitochondria damage, lipid peroxidation, ATP deprivation, ROS generation, nucleic acid fracture, eventually leading to neuronal death. However the molecular mechanism remain unclear. MCU is a recently identified mitochondrial calcium transport protein, new studies show that Pyk2-mediated MCU oligomerization is directly linked to an increase in cardiac mitochondrial calcium overload and induce apoptosis. Based on our understanding and previous work on Pyk2/MCU pathway, we hypothesize Pyk2/MCU pathway is involved in the process of neuron damage after ischemia. To further confirm this scientific hypothesis, the project is mainly to observe the changes of Pyk2, MCU and related factors in cell model and animal model with ischemia, to identify Pyk2/MCU pathway is relevant with mitochondrial function and apoptosis. By this project, it is promising to find new potential targets to protect mitochondria, and provide new experimental evidences for the mechanism research and drug development of brain ischemia stroke.

缺血性脑卒中是神经内科常见病，致残率和死亡率高。虽然超早期溶栓治疗有效，但多数患者难在规定时间窗内接受治疗。脑缺血后如何减轻神经细胞损伤促进神经功能恢复是目前临床面临的重要课题。梗死后神经损伤的关键之一是缺血后钙离子内流引起钙超载，从而引起线粒体受损、脂质过氧化、ATP匮乏、ROS生成增多等，最终导致神经元死亡。但其具体机制尚不十分清楚，相关靶点药物的临床效果仍有待提高和开发。MCU是新近鉴定出的线粒体钙转运蛋白，有研究认为启动经过Pyk2依赖的MCU活化导致心肌线粒体钙超载细胞凋亡。基于对Pyk2/MCU通路的认识和前期工作，我们设疑Pyk2/MCU通路参与了缺血后的神经损伤过程。为证实这一科学假说，本项目以细胞模型和动物模型为基础，深入系列研究Pyk2/MCU通路与缺血性脑卒中神经元损伤的相关性及机制。以期寻找新的线粒体保护途径，为缺血性脑卒中的机制研究和药物开发提供更多新的实验依据。

本课题以线粒体功能为关注点，探讨了Pyk2/MCU通路在缺血性脑卒中及动脉粥样硬化相关内皮损伤中的作用。建立SD-大鼠，MCU（+/+）、MCU（-/-）及MCU（+/-）小鼠MCAO模型。以此为基础，我们发现（1）Pyk2/MCU通路及其相关蛋白在大鼠脑梗死模型中可通过促进细胞内线粒体钙超载所致的线粒体损伤参与梗死后病理生理机制，并且通过促进细胞内线粒体钙超载所致的线粒体损伤参与神经细胞兴奋毒损伤后病理生理机制；（2）Pyk2/MCU通路在血管内皮细胞氧化损伤中发挥作用，尤瑞克林可改善氧化应激后血管内皮细胞损伤。（3）Pyk2/MCU通路参与了过氧化氢引起的内皮细胞损伤模型。瑞舒伐他汀通过抑制Pyk2/MCU通路保护了内皮细胞。（4）MCU低表达可通过保护线粒体功能保护缺血缺氧模型造成的神经损伤。以上研究成果共发表文章8篇，其中SCI收录2篇，核心期刊1篇。总之，通过本课题，明确了Pyk2/MCU通路与缺血性脑卒中发病机制的相关性，证实Pyk2/MCU通路适度低表达可以发挥线粒体保护作用，提示Pyk2/MCU途径可能成为新的线粒体保护途径，减轻缺血后神经元损害及动脉粥样硬化相关内皮损伤。为深入探讨缺血性卒中的致病机制、寻找新靶点、筛选治疗缺血性卒中的有效药物提供了重要的实验依据。