A proteomics approach to titin kinase mechanosignaling in striated muscle.

肌合成蛋白titin是哺乳动物中已知的最大的蛋白质，该基因的突变被认为是遗传性心脏病的最常见原因。Titin最初是作为横纹肌中的支架蛋白被发现的，最近的证据表明它在信号转导中起作用：人们假设Titin的调节和催化激酶结构域的力依赖相互作用可以为机械传感器和酪氨酸磷酸化的催化结构域（Y170）提供额外的调节水平。对遗传性肌肉疾病患者的突变分析将titin与肥厚/萎缩信号联系起来，我们已经证明激酶区域的缺失导致肥厚性心肌病。在这里，我们将建立与横纹肌中titin激酶（TK）和肥大/萎缩信号相关的分子途径，建立在我们在蛋白质组学和生成和分析心血管疾病动物模型方面的优势。我们将使用定位蛋白质组学来探测titin激酶结构域在体内的环境，并剖析其在机械转导和肥大信号传导中的作用。结合催化结构域的敲除（KO）和不同机械应力和应变来源的应用，我们将阐明激活TK的机械输入类型，然后采用候选和蛋白质组学方法分析下游事件。这包括TK作为枢纽与催化活性激酶的分析，以及对压力和体积的差异反应。这项研究对维持固定患者或老年人的肌肉质量以及生理性与病理性心脏肥大具有重要意义。

The sarcomeric protein titin is the largest known protein in mammals and mutations in the gene have been recognized as the most common cause of inherited heart disease. Titin was originally discovered as scaffolding protein in striated muscle, with recent evidence suggesting a role in signal transduction: It has been hypothesized that the force dependent interaction of titin’s regulatory and catalytic kinase domain could provide a mechanosensor and tyrosine phosphorylation of the catalytic domain (Y170) an additional level of regulation. The analysis of mutations in patients with hereditary muscle disease has linked titin to hypertrophy/atrophy signaling and we have shown that loss of the kinase region leads to hypertrophic cardiomyopathy. Here, we will establish the molecular pathways relating titin kinase (TK) and hypertrophy/atrophy signaling in striated muscle, building on our strength in proteomics and in generating and analyzing animal models of cardiovascular disease. We will use localization proteomics to probe the environment of the titin kinase domain in vivo and dissect its role in mechanotransduction and hypertrophy signaling. Combined with the knockout (KO) of the catalytic domain and application of different sources of mechanical stress and strain we will elucidate the type of mechanical input that activates the TK followed by a candidate and proteomics approach to analyze the downstream events. This includes the analysis of TK as a hub versus a catalytically active kinase and the differential response to pressure and volume. This research has implications for maintaining muscle mass in immobilized patients or the elderly and for physiological versus pathological hypertrophy of the heart.