RhoA signaling pathway in stretch mediated cardiac hypertrophy

了解心肌细胞如何转导拉伸信号来改变核转录事件，将有助于我们了解高血压或结构性心脏病引发的心脏肥厚的分级机制。我们提出的假设是，活化的RhoA对肌动蛋白细胞骨架和整合素激活的影响可能是连接拉伸依赖信号与心脏核转录因子表现的关键介质，从而诱导体内心脏肥大。RhoA是一种小分子量的gtp结合蛋白，作为控制各种细胞功能的分子开关，已被关注为肥厚信号的潜在介质。总体目标是破译连接机械拉伸信号的潜在受体到细胞骨架组装的信号通路。以及心脏生长反应。目的一：确定拉伸是否通过激活离体心肌细胞中的RhoA信号通路诱导心肌肥大。目的二：确定局部黏附激酶是否通过酪氨酸自磷酸化和/或与分离心肌细胞的下游信号因子相关联来整合拉伸信号。目的III：确定拉伸是否激活整合素连接激酶，以及是否表达激酶缺陷整合素连接激酶的激酶缺陷减轻压力过载导致的心脏肥厚。目的IV：在可诱导的转基因小鼠模型中，确定RhoA、局灶黏附激酶和整合素连接激酶及其突变的显性阴性种的作用，以及它们是否改变压力过载导致的心脏肥厚反应。

Understanding how cardiac myocytes transduce stretch signaling to alter nuclear transcriptional events will contribute greatly to our knowledge of the hierarchical mechanism which directs cardiac hypertrophy triggered by hypertension or structural heart disease. We propose the hypothesis that the effects of activated RhoA on the actin cytoskeleton and integrin activation might be the key mediator that links stretch dependent signaling to cardiac nuclear transcription factor performance, thus inducing cardiac hypertrophy in vivo. RhoA, a small molecular weight GTP-binding proteins acts a molecular switch that controls various cell functions and has received attention at a potential mediator of hypertrophic signals. The overall objective is to decipher the signaling pathways that link the potential receptors of the mechanical stretch signal to cytoskeleton assembly. and to the cardiac growth response. Aim I: to determine if stretch induces cardiac hypertrophy via activation of the RhoA signaling pathway in isolated cardiac myocytes. Aim II: to determine if focal adhesion kinase integrates the stretch signal through tyrosine auto-phosphorylation and/or by association with downstream signaling factors in isolate cardiac myocytes. Aim III: to determine if stretch activates integrin-linked kinase and if expression of kinase deficient of kinase deficient integrin-linked kinase attenuates cardiac hypertrophy facilitated by pressure overload. Aim IV: to determine the role of RhoA, focal adhesion kinase and integrin linked kinase and their mutated dominant negative species and whether they modify cardiac hypertrophic responses facilitated by pressure overload in inducible transgenic mouse models.