HIPK1下调介导运动诱导的生理性心肌肥厚及其机制研究

Heart failure (HF) is the end stage of cardiovascular disease and the main cause for HF patients’ death. It still lacks therapy for HF. Exercise could promote cardiomyocyte growth and play protective roles for HF. But the mechanism for exercise induced physiological cardiac hypertrophy is unknown. In our previous research, we found that homeodomain-interacting protein kinase 1( HIPK1 ) was down-regulated in exercised hearts. Furthermore, the knockdown of HIPK1 increased cardiomyocytes proliferation. These data indicate that HIPK1 might be a potential regulator for exercise induced physiological cardiac hypertrophy. In the present project, we will identify the role of HIPK1 in exercise induced physiological cardiac hypertrophy through both in vivo and in vitro loss-of-function and gain-of-function experiments. Swimming induced cardiac hypertrophy model will be used in vivo with transgenic mice and AAV9 virus injection. Primary cardiomyocyte proliferation and hypertrophy model will be used in vitro with HIPK1 overexpressing lentivirus and HIPK1 interference lentivirus infection. Mechanistically, based on microRNA-222 and HIPK1 double knockout mice, we will elucidate the regulation of microRNA-222 to HIPK1 in exercise induced cardiac physiological hypertrophy. Secondly, based on previous study, we propose that C/EBPβ might be the downstream gene of HIPK1 in cardiomyocyte. Next, we will perform rescue experiments in vitro and in vivo to identify the regulation of HIPK1 to C/EBPβ in exercise induced physiological cardiac hypertrophy. Overall, our project will prove that the down-regulation of HIPK1 contributes to exercise induced physiological cardiac hypertrophy and provide novel therapeutic targets for HF therapy.

心力衰竭是多种心脏疾病的终末阶段，目前缺乏治愈的方法。运动诱导的生理性心肌肥厚对于心力衰竭具有保护效应。但是，生理性心肌肥厚的发生机制尚未清楚。我们在前期工作中发现，HIPK1在运动诱导的生理性心肌肥厚中表达下调；HIPK1敲低促进心肌细胞增殖。本项目将结合慢病毒过表达和干扰载体以及心肌特异性敲除和过表达小鼠，在细胞水平和动物水平实施功能实验，明确HIPK1与运动诱导生理性心肌肥厚的关系。在分子机制上，鉴于已知MicroRNA-222对HIPK1的调节以及初步数据表明C/EBPβ可能是HIPK1的下游分子，我们将明确HIPK1是否介导了MicroRNA-222的功能；明确HIPK1下游调控机制；阐释HIPK1如何调控C/EBPβ；明确HIPK1是否能够防治心力衰竭。本项目将阐明HIPK1在运动诱导的生理性心肌肥厚中的作用及分子机制，为防治心力衰竭提供新靶点。

运动可以诱导生理性心肌肥厚，保护心脏抵抗病理性心肌肥厚和心力衰竭。同源结构域相互作用蛋白激酶1（homeodomain interacting protein kinase 1, HIPK1）在运动心脏下调，但HIPK1与运动诱导生理性心肌肥厚的关系及其是否调控心力衰竭先前是未知的。本项目首先构建了小鼠游泳诱导生理性心肌肥厚的模型，HIPK1在运动心脏显著下调。接着，在新生大鼠心肌细胞水平，明确了下调HIPK1可以促进心肌细胞的增殖，但不影响心肌细胞的面积，也不影响氧葡萄糖剥夺恢复（OGDR）和阿霉素（DOX）诱导的心肌细胞凋亡，并鉴定出CREB和C/EBPβ是HIPK1的下游分子。进一步，我们构建了主动脉弓缩窄（TAC）手术诱导的病理性心肌肥厚模型，敲低HIPK1可显著改善TAC术后的病理性心肌肥厚和心力衰竭，表现为心功能增强、心肌横截面积和纤维化面积减小，且敲低HIPK1能够在病理性心肌肥厚的心脏中降低p-CREB（S271）和C/EBPβ的表达。通过上述研究，本项目明确了HIPK1和运动诱导生理性心肌肥厚的关系，鉴定出下调HIPK1通过抑制CREB-C/EBPβ信号通路，促进心肌细胞增殖的下游分子机制，揭示了下调HIPK1抑制病理性心肌肥厚和心力衰竭的保护效应。综上，下调HIPK1在心肌保护中发挥着关键的作用，受运动下调的HIPK1可以抑制病理性心肌肥厚和心力衰竭。