Mst1蛋白在糖尿病心肌病“高血糖记忆”中的功能和作用机制研究

Recent randomized trials suggest that intensive glycaemic control fails to reduce heart failure-related events in patients with diabetes. The molecular cues underlying persistent myocardial damage despite normoglycaemia restoration, a phenomenon known as "hyperglycaemic memory", remain elusive. As reported, oxidative stress and apoptosis were markedly involved in the hyperglycaemic memory in diabetes. Interestingly, we have found that protein expression of Mst1 remained significantly overexpressed in streptozotocin-induced diabetic hearts even after subsequent normoglycaemia. We proposed that the circle of “oxidative stress and apoptosis”-Mst1-“oxidative stress and apoptosis” might mediate "hyperglycaemic memory" in the diabetic heats. .Firstly, we would verify whether overexpression of Mst1 would induce oxidative stress and apoptosis in cardiomyocytes by transfecting with recombinant adenovirus containing Mst1-overexpressing plaimid in cardiomyocytes in vitro and in vivo. Secondly, we would verify whether knockdown of Mst1 by transfeting with recombinant adenovirus containing Mst1 shRNA adenovirus particles in cardiomyocytes in vitro and in vivo would abate oxidative stress and reduce apoptosis when normoglycaemia is restored. Thirdly, we would verify whether knockout of cardiac Mst1 gene abate oxidative stress, reduce apoptosis, and restored cardiac function when normoglycaemia is restored. To elucidate the underlying molecular mechanism of modulation of Mst1 on oxidative stress and apoptosis, the apoptosis-related proteins and “mitochondria/reactive oxygen species (ROS)” and “Rac/NADPH oxidase/ROS” pathways would be evaluated in this work. .The study will provide novel insights to understand why diabetic cardiomyopathy progresses despite normalization of blood glucose levels.

最近的临床调查发现严格的血糖控制无法减少糖尿病患者心衰相关事件的发生，“高血糖记忆”效应是导致其发生的主要原因。据报道血糖控制后氧化应激和凋亡的持续存在促进了“高血糖记忆”效应的发生，然而其中具体的分子机制尚不清楚。我们前期的研究发现：链脲霉素诱导的糖尿病心肌中Mst1蛋白表达增加；严格的血糖控制后，心肌中Mst1蛋白仍然高表达。我们推测：Mst1蛋白介导的“氧化应激和凋亡/Mst1/氧化应激和凋亡”循环促进了糖尿病心肌中“高血糖记忆”效应的发生。本课题拟通过调节Mst1蛋白的表达，在细胞和整体水平观察其对“高血糖记忆”效应中氧化应激和细胞凋亡的影响，并通过心脏特异性Mst1基因敲除观察该蛋白在糖尿病心肌“高血糖记忆”效应中的作用和机制。最终阐述清楚Mst1蛋白在糖尿病心肌病“高血糖记忆”效应发生过程中所起到的作用并指明其作为潜在治疗靶点的意义。

最近的临床调查发现严格的血糖控制无法减少糖尿病患者心衰相关事件的发生，“高血糖记忆”效应是导致其发生的主要原因。本研究的目的是探索Mst1蛋白在糖尿病心肌中“高血糖记忆”效应发生过程中作用和机制。链脲霉素诱导的糖尿病心肌中Mst1蛋白表达增加；严格的血糖控制后，心肌中Mst1蛋白仍然高表达。细胞水平结果发现抑制Mst1蛋白表达可以减轻心肌细胞“高血糖记忆”效应中早期凋亡、氧化应激、线粒体功能失调的发生。动物水平结果发现Mst1基因敲除可以明显改善“高血糖记忆”中小鼠心肌功能，抑制活性氧的生成，维持线粒体功能。在高血糖记忆中，当Mst1被下调或被敲除后，心肌细胞中AMPK通路被激活。更为重要的是通过给予AMPK激动剂治疗可以逆转Mst1高表达在心肌细胞中对线粒体、氧化应激和凋亡的不利作用。综上所述，Mst1通过调控AMPK信号通路，诱发心肌细胞中线粒体功能失调、氧化应激、凋亡，从而促进了“高血糖记忆”效应的发生。

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