REGULATION OF MYOCARDIAL GROWTH AND DEATH BY THE HIPPO PATHWAY

总结 Hippo信号通路是一种进化上保守的信号通路，其控制器官大小和 通过调节细胞的生长和死亡来控制肿瘤的发生。我们已经证明了海马通路的每个组成部分 与心力衰竭的发病机制密切相关。雅普是Hippo通路的核效应子， 在压力超负荷（PO）时短暂激活，但在PO慢性期下调 和心力衰竭心脏特异性下调雅普可抑制心肌肥厚，但促进心脏 在PO急性期的失败，表明内源性雅普是有益的，并介导代偿 在PO急性期肥大。虽然雅普在PO的慢性期下调， 在此阶段强制激活雅普是有害的，并促进心力衰竭，这是由于 心肌细胞因此，在PO期间，雅普可以以上下文相关的方式是保护性的或有害的。 然而，在PO期间，心脏中的雅普是有益的还是有害的仍有待证明。我们 初步结果表明，雅普通过刺激糖酵解促进代偿性心肌肥大 通过在PO急性期以类似于有氧的方式上调心脏中的GLUT 1， 糖酵解，即癌细胞中的“瓦尔堡效应”。在这里，我们假设内源性雅普介导 PO存在下心肌细胞的代偿性肥大和存活通过转录 GLUT 1和糖酵解和生物合成分子的后续上调。雅普与 TEAD和HIF-1介导并参与GLUT 1的上调，GLUT 1在PO的急性期被激活， 在PO的慢性期由于不同的伴侣转录因子的可用性而失活， 雅普。为了验证这些假设，我们将：1。(a)证明内源性雅普在 介导响应于急性PO的糖酵解的上调。(b)证明雅普的激活诱导 通过GLUT 1和PKM 2依赖性机制积累糖酵解中间体。(c)证明 YAP诱导的GLUT 1上调对于糖酵解的维持和随后的糖酵解是必不可少的。 对急性PO的代偿性心脏肥大的上调。2.证明YAP诱导的 GLUT 1的上调通过雅普与TEAD和/或HIF-1 α的直接结合介导， 急性PO时的协同作用。我们将使用转基因小鼠模型，培养成年 心肌细胞，代谢组学分析，转录组分析和ChIP测序分析，以解决 这些问题该项目的成功完成将为分子开关的研究提供新的信息 控制心脏糖酵解途径和代偿性肥大，以及雅普与 控制信号传导机制，以介导PO期间心脏中的有益和有害作用。

Summary The Hippo signaling pathway is an evolutionarily conserved signaling pathway that controls organ size and tumorigenesis by regulating cell growth and death. We have shown that each component of the Hippo pathway is intimately involved in the pathogenesis of heart failure. YAP, the nuclear effector of the Hippo pathway, is transiently activated in response to pressure overload (PO) but downregulated during the chronic phase of PO and heart failure. Cardiac specific downregulation of YAP inhibits cardiac hypertrophy but promotes heart failure during the acute phase of PO, suggesting that endogenous YAP is salutary and mediates compensatory hypertrophy during the acute phase of PO. Although YAP is downregulated during the chronic phase of PO, forced activation of YAP at this stage is detrimental and promotes heart failure, due to de-differentiation of cardiomyocytes. Thus, YAP can be either protective or detrimental in a context-dependent manner during PO. However, it remains to be shown what makes YAP either salutary or detrimental during PO in the heart. Our preliminary results suggest that YAP promotes compensatory cardiac hypertrophy by stimulating glycolysis through upregulation of GLUT1 in the heart during the acute phase of PO, in a manner similar to aerobic glycolysis, namely the “Warburg effects” in cancer cells. Here we hypothesize that endogenous YAP mediates compensatory hypertrophy and survival of cardiomyocytes in the presence of PO through transcription of GLUT1 and consequent upregulation of glycolysis and biosynthetic molecules. YAP acts cooperatively with TEAD and HIF-1 and is involved in upregulation of GLUT1 that is activated during the acute phase of PO but inactivated during the chronic phase of PO due to differential availability of the partner transcription factors of YAP. To test these hypotheses, we will: 1. (a) Demonstrate that endogenous YAP plays an essential role in mediating upregulation of glycolysis in response to acute PO. (b) Demonstrate that activation of YAP induces accumulation of glycolytic intermediates through GLUT1- and PKM2-dependent mechanisms. (c) Demonstrate that YAP-induced upregulation of GLUT1 is essential for the maintenance of glycolysis and consequent upregulation of compensatory cardiac hypertrophy in response to acute PO. 2. Demonstrate that YAP-induced upregulation of GLUT1 is mediated through direct binding of YAP to TEAD and/or HIF-1 and resultant cooperative actions during acute PO. We will use genetically altered mouse models, cultured adult cardiomyocytes, metabolomic analyses, transcriptome analyses and ChIP sequencing analyses to address these issues. Successful completion of this project will provide novel information about the molecular switch that controls the glycolytic pathway and compensatory hypertrophy in the heart and how YAP differentially controls signaling mechanisms to mediate both salutary and detrimental effects in the heart during PO.