hERG钾通道泛素化介导糖尿病诱发获得性LQTS的新机制及罗格列酮的干预作用研究

The hERG potassium channel dysfunction is an important reason for diabetes-induced Long QT syndrome (LQTS), it’s easy to induce sudden cardiac death, but the molecular mechanism of diabetes-induced hERG channel dysfunction has not been completely revealed. This study aims to prove the molecular target of diabetes-induced inhibition of hERG channel in vitro and in vivo. To elucidate the role of ubiquitin ligase Nedd4-2-mediated hERG potassium channel ubiquitination in diabetes induced hERG channel dysfunction. To explore the regulatory pathway of affects Nedd4-2 activity. To elucidate the effect of transfection of plasmid knockout Nedd4-2 with transfection plasmid, specifically intervention of hERG potassium channel ubiquitination, which has the effect of reversing diabetes-induced LQTS. Nedd4-2-mediated hERG potassium channel ubiquitination was used to screen the drug - rosiglitazone, which has the effect of rescuing diabetes-induced LQTS. In this study, we investigate the role of Nedd4-2 mediated ubiquitination in diabetic LQTS from multiple perspectives, and reveal the new target of diabetes-induced LQTS for the first time. Moreover, we provide a new molecular mechanism and intervention strategy for the prevention and treatment of diabetes-induced LQTS. And have great significance on effectively preventing diabetes-induced LQTS and sudden cardiac death.

hERG钾通道功能障碍是糖尿病诱发长QT间期综合征（LQTS）的主要原因，它的发生易诱发心源性猝死，然而糖尿病发生时影响hERG通道功能障碍的具体机制尚未被完全揭示。本项目将通过离体与在体实验揭示糖尿病抑制hERG通道功能的分子靶点，阐明泛素连接酶Nedd4-2介导的hERG钾通道泛素化在糖尿病诱发hERG通道功能障碍中的作用；探索糖尿病发生时影响Nedd4-2活性的调控通路；证明敲除Nedd4-2，特异性干预hERG钾通道泛素化，具有拯救糖尿病性LQTS的作用；通过干预Nedd4-2介导的hERG钾通道泛素化筛选出具有拯救糖尿病性LQTS作用的药物—罗格列酮。本项目从多层面探讨Nedd4-2介导的hERG钾通道泛素化在糖尿病性LQTS中的作用，首次揭示糖尿病诱发LQTS的分子新靶点，拓展了对糖尿病诱发LQTS的理论和干预手段的新认识，对有效防治糖尿病诱发LQTS和心源性猝死具有重要意义。

糖尿病是危害人类健康的重大疾病之一，超过70%的糖尿病患者会发展出糖尿病心肌病，已成为糖尿病致死的主要原因之一。糖尿病心肌病中常会出现QT间期延长。在所涉及的机制中，hERG通道表达异常在糖尿病诱发的长QT间期综合征(Long QT syndrome, LQTS)中发挥主导作用。然而目前糖尿病发生时hERG通道表达异常的分子机制尚未被完全揭示，本项目旨在揭示糖尿病抑制hERG通道功能的分子靶点。经过大量实验研究发现，泛素连接酶Nedd4-2在糖尿病诱发hERG通道功能障碍中发挥重要作用，进一步研究发现高糖损伤乳鼠心肌细胞时，hERG蛋白表达减少，乳鼠心肌细胞APD延长；miR-195-5p在高糖情况下表达显著上调；miR-195-5p通过抑制SGK1表达，进而抑制Nedd4-2蛋白磷酸化，促进hERG通道蛋白降解；证明通过干扰miR-195-5p- SGK1- Nedd4-2能够对抗高糖导致的hERG蛋白表达减少，缩短乳鼠心肌细胞APD。因此miR-195-5p- SGK1- Nedd4-2通路可作为糖尿病诱发LQTS的分子新靶点，对防治糖尿病诱发的获得性LQTs的具有重要意义。

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