Infammatory Proteases and Proteases and Diabetic Cardiomyopathy

描述（由申请人提供）：糖尿病性心肌病（DCM）以左心室重构和功能障碍为特征，与动脉粥样硬化、冠心病或高血压无关。导致这种疾病的机制很复杂，而且人们对其知之甚少。一个新兴的概念是炎症可能与胰岛素受体（IR）和/或胰岛素样生长因子受体（IGF-1R）信号的改变有关，从而导致DCM的心脏结构和功能不良后果。然而，炎症途径在DCM发展中的作用仍然存在争议，有待确定。该建议通过抑制炎性丝氨酸蛋白酶（ISPs）来对抗DCM发展过程中诱导的不良心脏重构，炎性丝氨酸蛋白酶（ISPs）不仅是免疫反应的重要调节因子，而且是参与心脏重构的各种生物途径的调节因子。我们发现，体内ISPs的遗传抑制可减轻DCM诱导的IR/IGF-1R信号下调和不良心脏重构，而不影响高血糖水平。此外，用isp处理分离的肌细胞，分别通过激活E3泛素连接酶Cbl和泛素蛋白酶体系统（UPS），导致IR/IGF-1R泛素化和降解。因此，我们假设在糖尿病发展过程中释放的isp促进IR/IGF-1R泛素化和降解，导致心肌细胞死亡和心功能障碍。这与isp对Cbl泛素连接酶激活和随后的IR/IGF-1R蛋白酶体降解的影响有关。目的1将确定泛素连接酶Cbl和UPS在体外响应isp的IR/IGF-1R转换中的机制作用；目的2将确定Cbl失活在DCM诱导的IR/IGF-1R信号下调和不良心脏重构中的作用；最后，Aim 3将确定isp抑制对DCM诱导的IR/IGF-1R信号下调、Cbl激活和肌细胞损失的影响。这项拟议的研究将整合ISPs和泛素连接酶Cbl在IR/IGF-1R转换和心肌细胞死亡中的新作用，这可能有助于DCM发展过程中的不良心脏重塑和功能，并确定ISPs是否应被视为治疗DCM患者的新靶点。

DESCRIPTION (provided by applicant): Diabetic cardiomyopathy (DCM) is characterized by left ventricular remodeling and dysfunction independent of atherosclerosis, coronary heart disease, or hypertension. The mechanisms responsible for this disorder are complex and poorly understood. An emerging concept is that inflammation might be linked to alteration in insulin receptor (IR) and/or insulin-like growth factor receptor (IGF-1R) signaling, thus leading to the maladaptive cardiac structural and functional consequences of DCM. However, the role of inflammatory pathways in the development of DCM is still controversial and remains to be determined. This proposal antagonizes the adverse cardiac remodeling induced during the development of DCM through inhibition of inflammatory serine proteases (ISPs) that have emerged as important regulators not only of the immune response but also in the regulation of various biological pathways involved in cardiac remodeling. We found that genetic inhibition of ISPs in-vivo attenuated IR/IGF-1R signaling down-regulation and adverse cardiac remodeling induced by DCM without affecting hyperglycemia levels. Moreover, treatment of isolated myocytes with ISPs led to IR/IGF-1R ubiquitylation and degradation through activation of E3 ubiquitin ligase Cbl and ubiquitin proteasome system (UPS), respectively. Therefore we hypothesized that ISPs, released during the development of diabetes, promote IR/IGF-1R ubiquitylation and degradation that lead overtime to myocyte death and cardiac dysfunction. This is related to the effect of ISPs on Cbl ubiquitin ligase activation and subsequent proteasomal degradation of IR/IGF-1R. Aim 1 will determine the mechanistic role of the ubiquitin ligase Cbl and the UPS in IR/IGF-1R turnover in response to ISPs in-vitro; Aim 2 will determine the role of Cbl inactivation in IR/IGF-1R signaling down-regulation and adverse cardiac remodeling induced by DCM; and finally Aim 3 will determine the effect of ISPs inhibition on IR/IGF-1R signaling down-regulation, Cbl activation, and myocyte loss induced by DCM. The proposed study will integrate the novel role of ISPs and ubiquitin ligase Cbl in IR/IGF-1R turnover and myocyte death that may contribute to adverse cardiac remodeling and function during the development of DCM and determine whether ISPs should be considered a new target for therapy to treat patients with DCM.