VGLL4在心肌重塑过程中的功能及分子机制的研究

Heart failure has very high morbidity and mortality worldwide, so it is crucial to dig deep and reveal the molecular mechanism in heart hypertrophy to heart failure transition. VGLL4 is a new cofactor in Hippo pathway, it competes with YAP to form a complex with TEAD, acts like a tumor suppressor in cancer. In this project, we try to study VGLL4 function in heart field. We first construct Vgll4-eGFP reporter mouse line, to describe VGLL4 express pattern during heart development and remodeling. We found that VGLL4 is mainly expressed in cardiomyocytes after birth, and translocated into nuclear when heart under pressure overload stress. We further use cTnT:Cre, Vgll4fl/fl mouse line to knockout Vgll4 in cardiomyocytes and found heart hypertrophy and fibrosis are inhibited and heart function remain normal in TAC and AngII induced heart stress model. So we hypothesize that VGLL4 may plays an important role in heart remodeling and heart failure. We will further perform RNA sequencing and ChIP sequencing to find VGLL4 regulated target genes and disclose the regulation mechanism. Finally, we will try to use AAV9 to knockdown Vgll4 in cardiomyocyte to perform gene therapy experiment to test if cardiac hypertrophy could be inhibited. It will be promising if we found the gene to inhibit hypertrophy or heart failure progression, this study will provide us with new theoretical basis and novel strategies for clinical treatment.

心力衰竭的发病率和致死率逐年上升，深入研究心肌重塑向心力衰竭转变进程中的分子机制具有重要的临床意义。VGLL4是最近发现的Hippo信号通路中的转录辅助因子，被认为是一个肿瘤抑制因子。本项目拟从心脏稳态和心肌重塑的角度研究VGLL4的功能。我们构建了VGLL4报告基因小鼠，将系统地阐明在小鼠在生理或病理条件下，心脏中VGLL4的表达谱。我们还构建了组织特异性基因敲除VGLL4的工具小鼠，发现敲除心肌细胞中VGLL4后，在心脏超负荷和心脏损伤模型中，心肌肥大和纤维化程度显著降低且心功能维持正常，提示VGLL4在心肌重塑向心力衰竭转变过程中有重要作用。本项目将结合RNA测序和ChIP测序，寻找受VGLL4调控的靶基因，并尝试利用AAV病毒载体在心肌肥大小鼠模型的心肌细胞中沉默Vgll4基因，检测是否也能够抑制或减缓心衰的进展，这将在临床上为心肌病患者进行基因治疗提供新的理论基础。

VGLL4是最近发现的Hippo信号通路中的转录辅助因子，被认为是一个肿瘤抑制因子。Vgll4在各组织器官中的功能成为近年来研究热点，其在心脏出生后生长、瓣膜发育、骨发育、肌肉再生过程中的功能陆续被发现。然而由于缺少可以用于免疫组织化学分析的抗体，Vgll4在各组织器官中的表达谱仍有待阐明。本项目拟从心脏稳态和心肌重塑的角度研究VGLL4的功能。我们还成功构建了VGLL4-DreER报告基因工具小鼠，将系统地阐明在小鼠在生理或病理条件下，心脏及其他组织器官中VGLL4的表达谱。我们首先利用心脏特异性基因敲除VGLL4的cTnT-Cre工具小鼠，发现敲除心肌细胞中VGLL4后，在心脏超负荷和心脏损伤模型中，心肌肥大和纤维化程度显著降低且心功能维持正常，提示VGLL4在心肌重塑向心力衰竭转变过程中有重要作用。进一步结合RNA测序分析，Vgll4通过调节Dusp1的表达水平来控制p38信号通路的激活。该项发现在临床上为心肌病患者治疗提供新的理论基础。