JAK2/STAT3 和PI3K/Akt/mTOR信号通路及锌稳态介导ANP抵抗再灌注损伤的保护作用研究

There is no an effective therapeutic means for the treatment of myocardial ischemia/reperfusion injury caused by acute myocardial infarction. Zinc dyshomeostasis characterized by a loss of zinc at reperfusion has been demonstrated to contribute to cardiac reperfusion injury. Accordingly, the maintenance of zinc homeostasis is one of the important therapeutic targets for the treatment of reperfusion injury. Our recent study showed that ANP and zinc can protect the heart from reperfusion injury by preventing the mPTP opening through glycogen synthase kinase-3β. We further found that ANP can prevent zinc loss and increase the zinc transporter Zip2 expression. Studies have demonstrated that the JAK2/STAT3 and PI3K/Akt/mTOR singaling pathways have been demonstrated to play an important role in the prevention of reperfusion injury. However, it is unknown if PI3K/Akt/mTOR, JAK2/ STAT3, and zinc play a role in the cardioprotective effect of ANP at reperfusion. This project will adopt the methods of physiology, cell biology, and molecular biology to test: 1）The role of zinc in the cardioprotection with ANP. 2）The roles of the PI3K/Akt/mTOR and JAK2 / STAT3 pathways in the modulation of zinc homeostasis by ANP. This project will not only shed light on the molecular mechanism of the prevention of myocardial reperfusion injury by ANP but also provide new targets and strategies for the prevention of myocardial reperfusion injury.

急性心肌梗死引起的再灌注损伤尚无有效治疗方法。研究指出再灌注损伤与心脏锌离子丢失为特征的锌稳态失衡有关，调节锌稳态是抗再灌注损伤的靶点之一。心脏自身分泌的心房钠尿肽（ANP）具有心肌保护作用，但与锌稳态之间的相互关系尚无报道。研究证实ANP和Zn2+均通过抑制GSK-3β活性和mPTP开放而减轻再灌注损伤；同时ANP减缓再灌注时的Zn2+丢失并增加锌转运蛋白（Zip2）的表达。PI3K/Akt/mTOR和JAK2/STAT3信号通路参与再灌注损伤的保护。但PI3K/Akt/mTOR和JAK2/STAT3、锌稳态在 ANP抵制再灌注损伤中的具体作用及其机制尚不清楚。本项目将探讨：ANP对再灌注心脏锌稳态的影响； PI3K/Akt/mTOR和JAK2/STAT3在ANP调节锌稳态及抗再灌注损伤中的作用及其机制。本项目将揭示ANP保护再灌注心脏的详细分子机制，为防止再灌注损伤提供新的靶点和思路。

急性心肌梗死引起的再灌注损伤尚目前无有效治疗方法。研究指出，再灌注损伤与心脏锌离子丢失为特征的锌稳态失衡有关，调节锌稳态是抵抗再灌注损伤的靶点之一，同时心脏自身分泌的心房钠尿肽（ANP）具有心肌保护作用。本研究发现ANP可以减少大鼠离体和在体再灌注心脏的心肌梗死面积，并且ANP-/-小鼠再灌注心脏的心功能指标均明显低于野生型小鼠再灌注损伤心脏的心功能指标，但是预处理ANP时心功能明显好转。进一步的实验证实，在体和离体大鼠再灌注心脏以及ANP-/-小鼠再灌注心脏中，ANP通过增加锌离子转运蛋白ZiP2的表达及抑制ZnT8的表达，可以减缓再灌注时Zn2+丢失从而起到心肌保护作用。同时在体和离体实验中发现，ANP和锌离子均能抑制再灌注时增加的Hif-1ɑ活性，同时ANP可以增加PI3K/Akt活性。利用PI3K/Akt抑制剂LY294002和Hif-1ɑ的抑制剂2-Methoxyestradiol预处理后发现，LY294002可以逆转ANP对Zip2表达增加和ZnT8表达减少的效应，但是2-Me却不能逆转。此结果提示ANP对锌离子转运蛋白的调节作用可能与增加PI3K/Akt活性相关，从而减缓缺氧应激，最终减少Hif-1ɑ的活性相关。本项目揭示了ANP保护再灌注心脏的分子机制，为防止再灌注损伤提供新的靶点和思路。