钠钾泵/PI3K1A/Akt信号轴在心室重构中的作用和机制研究

Pathological ventricular remodeling is the pre-event of chronic heart failure.In earlier studies ,the applicant found that the binding of Na,K ATPase with the ligand-ouabain could activate PI3K1A/Akt signaling pathway in cardiac myocytes.So we wonder if the Na,K ATPase signaling function may play a role in the process of ventricular remodeling and the project is designed as follows.The in vitro experiments of culturing adult mice cardiac myocytes and mice tansverse aortic constriction model will be involved.We will explore the effects and mechanisms of Na,K ATPase/PI3K1A/Akt signaling axis activation in the cardiac myocyte pathological hypertrophy and apoptosis induced by isoprenaline,also the effects in the process of ventricular remodeling and cardiac dysfunction.Furthermore,with the methods of adenovirus transfection induced gene silence and gene knock-out ,or treatments with PI3K1A and Akt enzyme inhibitors,we decrease or inhibit the activation of Na,K ATPase/PI3K1A/Akt signaling pathway by down-expressiong of Na,K ATPase or inhibition of enzyme activity.Then the effects of Na,K ATPase signaling transduction in cardiomyocytes hypertrophy and apoptosis,ventricular remodeling and cardiac dysfunction will be rechecked.This study will supply some evidences for improving ventricular remodeling by exploring the function and mechanism of Na,K ATPase signal transduction in the pathological ventricular remodeling,and also the new effect of ouabain,one of the endogenous digitalis-like susbtances.

病理性心室重构是慢性心功能衰竭必经过程。申请者前期研究发现钠钾泵与配体哇巴因结合可以激活心肌细胞PI3K1A/Akt信号通路，可能参与调控心室重构过程，但具体作用及机制不详。本课题拟通过心肌细胞分离培养和构建小鼠主动脉狭窄致心衰模型技术，借助腺病毒转染沉默基因、基因敲除等方法，研究哇巴因激活钠钾泵/PI3K1A/Akt信号轴对异丙肾上腺素诱导心肌病理性肥大和凋亡，以及压力负荷致心室重构、心功能衰竭的保护作用及机制；并观察在降低钠钾泵表达、使用PI3K1A、Akt激酶抑制剂等干预手段下调钠钾泵/PI3K1A/Akt信号轴后，对该通路在病理性心室重构、心功能衰竭中作用的影响。本课题将部分阐明钠钾泵信号传导功能在病理性心室重构中的作用机制和内源性洋地黄样物质-哇巴因的新功效，为寻求拮抗心室重构、心功能衰竭的手段提供依据。

慢性心衰是困扰人类的重要疾病，本课题旨在探索干预心室重构的可能途径，以期为阻断心衰的病理进程提供切实可行的办法。目前大量研究发现洋地黄类制剂可以通过诱导钠钾泵信号传导功能改善心肌的代谢，哇巴因是洋地黄类药物的一种，前期研究发现哇巴因可以通过激活心肌细胞钠钾泵信号传导功能导致心肌细胞生理性肥大，我们的课题研究主要围绕哇巴因-钠钾泵信号通路是否可以阻断心肌病理性肥大而展开。近三年来，我们课题组成功建立并稳定了成年小鼠心肌体外分离术，使用Western Blot法检测到低剂量哇巴因可以阻断ISO激活的病理性信号通路，用RT-PCR、[3H]-亮氨酸掺入法检测到心肌细胞在ISO刺激下的病理性肥大可以用哇巴因改善。动物实验发现TAC模型小鼠皮下埋植哇巴因微泵后，心肌肥大和凋亡情况较对照组明显好转。目前的研究结果揭示了哇巴因通过激活钠钾泵Akt/PI3K信号通路可以拮抗病理性心肌肥大，为调控钠钾泵Akt/PI3K信号通路从而改善心室重构提供了理论基础。