PHLDA1在病理性心肌肥厚诱发心力衰竭中的作用及机制研究

Heart failure is the final outcome of most patients with cardiovascular disease, and pathological cardiac hypertrophy is one of the important pathological mechanisms of heart failure. AKT-mediated signaling and apoptosis play important roles in heart failure induced by pathological cardiac hypertrophy. PHLDA1 is a negative regulator of AKT, which regulates cell proliferation and apoptosis by inhibiting AKT. At present, the functional research on PHLDA1 focuses on tumors, and there is no report on the function of PHLDA1 on pathological cardiac hypertrophy-induced heart failure. Our preliminary study showed that PHLDA1 protein expression was significantly reduced in myocardial tissue of patients with heart failure, and the loss of PHLDA1 gene may lead to a more severe pathological cardiac hypertrophy phenotype. However, the role and its mechanism of PHLDA1 on heart failure induced by pathological cardiac hypertrophy need to be further studied. This study is designed to investigate the role and elucidate its mechanism of PHLDA1 in the pathogenesis of heart failure induced by pathological cardiac hypertrophy and to explore new targets and strategies for pathological cardiac hypertrophy and heart failure by employing cardiomyocyte-specific PHLDA1 knockout mice, cardiomyocyte-specific PHLDA1 transgenic mice and in vitro cell experiments.

心力衰竭是大多数心血管疾病患者的最终结局，而病理性心肌肥厚是心力衰竭重要的病理机制之一。AKT介导的信号通路和细胞凋亡在病理性心肌肥厚诱发的心力衰竭中发挥重要作用。PHLDA1是一种AKT的负性调节因子，其可通过抑制AKT调控细胞增殖和凋亡。目前关于PHLDA1的功能研究集中于肿瘤方面，对PHLDA1在病理性心肌肥厚诱发心力衰竭中的功能国内外未见相关报道。我们前期的研究显示，PHLDA1在心力衰竭患者心肌组织中的蛋白表达是显著降低的，PHLDA1基因缺失可导致更严重的病理性心肌肥厚。但PHLDA1在病理性心肌肥厚诱发心力衰竭中的作用及其机制有待于我们深入研究。本项目拟应用心肌细胞特异性PHLDA1基因敲除小鼠、心肌细胞特异性PHLDA1转基因小鼠以及体外细胞实验，探讨PHLDA1在病理性心肌肥厚诱发心力衰竭的作用，并阐明其作用机制，为防治病理性心肌肥厚和心力衰竭探寻新靶点和新策略。

AKT介导的信号通路在病理性心肌肥厚诱发的心力衰竭中发挥重要作用。PHLDA1是一种AKT的负性调节因子。本项目旨在阐明PHLDA1在病理性心肌肥厚诱发心力衰竭中的作用及机制。.通过运用重组腺病毒感染原代大鼠心肌细胞，并给予Ang II刺激构建心肌细胞肥大模型；通过运用心肌细胞特异性PHLDA1基因敲除小鼠和转基因小鼠，并给予主动脉缩窄术构建动物模型，综合评价PHLDA1对心力衰竭的影响。并通过WB实验和逆转实验阐明PHLDA1影响心力衰竭的机制。.系列实验结果表明，PHLDA1的蛋白表达在Ang II刺激的心肌细胞和压力负荷诱导的小鼠肥厚心肌组织中显著下降。离体细胞实验发现干扰PHLDA1表达可促进Ang II诱导的心肌细胞肥大，而过表达PHLDA1可显著抑制心肌细胞肥大。在体动物实验通过心功能检测、H&E染色、WGA染色、PSR染色以及RT-PCR检测心肌肥厚和心肌纤维化标志物等分别从心脏功能、心脏大体形态、心肌细胞水平和分子水平等多个层面发现心肌细胞特异性PHLDA1基因缺失可促进心肌肥厚和纤维化的发生发展，进一步加剧病理性心肌肥厚诱发心力衰竭；而PHLDA1过表达可抑制心肌肥厚和纤维化的进程，从而改善心力衰竭。WB实验和逆转实验表明PHLDA1主要是通过抑制AKT-mTOR-GSK3β-P70S6K信号通路发挥作用。.本项目结果表明，PHLDA1通过抑制AKT-mTOR-GSK3β-P70S6K信号通路来减缓心肌肥厚和心肌纤维化的发生发展，从而改善病理性心肌肥厚诱发心力衰竭。增加心脏组织中PHLDA1的表达有可能成为临床防治病理性心肌肥厚和心力衰竭的新策略。