Inflammatory Proteases and Diabetic Cardiomyopathy

描述(申请人提供)：糖尿病心肌病(DCM)的特征是左室重构和功能障碍，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，人们对此知之甚少。一个新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，从而导致扩张型心肌病(DCM)心脏结构和功能的不良适应后果。然而，炎症通路在扩张型心肌病发生发展中的作用仍存在争议，有待进一步研究。这一建议通过抑制炎性丝氨酸蛋白酶(ISPs)来拮抗DCM发展过程中诱导的不利心脏重构。炎症丝氨酸蛋白酶不仅是免疫反应的重要调节因子，也是参与心脏重构的各种生物学途径的调节因子。我们发现，体内ISPs的遗传抑制减弱了DCM诱导的IR/IGF-1R信号下调和不利的心脏重构，而不影响高血糖水平。此外，ISPs可通过激活E3泛素连接酶Cb1和泛素蛋白酶体系统(UPS)诱导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ISPs促进IR/IGF-1R泛素化和降解，从而导致心肌细胞死亡和心功能障碍。这与ISPs对Cbl泛素连接酶激活及随后IR/IGF-1R蛋白酶体降解的影响有关。目的1研究泛素连接酶Cb1和UPS在体外ISPs诱导IR/IGF-1R转归中的作用机制；Aim 2研究Cb1失活在DCM诱导IR/IGF-1R信号下调和不良心脏重构中的作用；Aim 3确定ISPs抑制DCM诱导的IR/IGF-1R信号下调、Cb1激活和心肌细胞丢失的作用。这项拟议的研究将整合ISPs和泛素连接酶Cbl在IR/IGF-1R周转和心肌细胞死亡中的新作用，这些作用可能在DCM的发展过程中导致不利的心脏重构和功能，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.