SUMO1 and SERCA2a Function

描述（由申请人提供）：尽管药物治疗和新型器械取得了重大进展，但美国充血性心力衰竭的发病率仍在持续增加。因此，迫切需要新的治疗方法来治疗心力衰竭。 随着对心力衰竭发病机制的深入了解，新的靶点不断涌现。 心力衰竭的一个关键异常是钙离子处理缺陷，已显示其与心肌细胞中异常肌浆网（SR）功能相关。SERCA2a的表达和活性降低已在心力衰竭的多种动物模型和从经历移植的患者的衰竭心脏分离的心肌细胞中显示。在心力衰竭实验模型中，恢复SERCA2a表达与分离的心肌细胞的变力性和收缩性改善以及心脏功能改善相关。最近，我们的小组进行了首次在人随机基因治疗试验，使用腺相关1型载体携带SERCA2a。在这项试验中，我们发现向患有晚期心力衰竭的患者递送AAV1.SERCA2a导致患有收缩性心力衰竭的患者的总体临床状态的改善，进一步突出了SERCA2a作为这种情况下的治疗靶点的潜在重要性。我们之前的工作，导致了临床试验的开始，是基于 这一前提是SERCA2a的总蛋白表达的变化在心力衰竭中观察到的钙循环异常中是关键的。最近，我们发现SERCA2a的水平和活性与特定细胞质蛋白SUMO 1（小泛素样修饰物1型）的水平平行调节。SUMO化参与蛋白质转运、基因转录、DNA复制和修复等多种细胞过程。我们发现SERCA2a和SUMO 1水平在心力衰竭模型和衰竭的人类心肌中均降低。 我们发现，在HF小鼠模型中，增加SUMO 1水平可改善血流动力学性能并降低死亡率。 我们现在建议进一步表征SUMO 1在调节SERCA 2a功能中的分子机制，并评估调节SERCA 2a SUMO化的多种途径。

DESCRIPTION (provided by applicant):The incidence of congestive heart failure continues to increase in the United States despite significant advances in pharmacological therapy and novel devices. For this reason, there is an urgent need for novel therapies to treat heart failure. With a better understanding of the molecular mechanisms involved in the pathogenesis of heart failure, new targets are emerging. A key abnormality in heart failure is defective handling of calcium ions which has been shown to be related to abnormal sarcoplasmic reticulum (SR) function in cardiac myocytes. Reduced expression and activity of SERCA2a have been shown in multiple animal models of heart failure and in cardiomyocytes isolated from failing hearts explanted from patients undergoing transplantation. Restoring SERCA2a expression is associated with improved inotropy and lusitropy of isolated cardiomyocytes and with improved cardiac function in experimental models of heart failure. More recently, our group carried out a First-in-Man randomized gene therapy trial, using adeno-associated type 1vector carrying SERCA2a. In this trial, we found that AAV1.SERCA2a delivered to patients with advanced heart failure led to an improvement in the overall clinical status of patients with systolic heart failur, further highlighting the potential importance of SERCA2a as a therapeutic target in this condition. Our previous work, which led to the initiation of the clinical trials, was based on the premise that changes in the total protein expression of SERCA2a was critical in the calcium cycling abnormalities observed in heart failure. More recently, we found that the levels and activity of SERCA2a are modulated in parallel with the levels of a specific cytoplasmic protein SUMO1 (small ubiquitin-like modifier type 1). SUMOylation has been found to be involved in many cellular processes such as protein transport, gene transcription and DNA replication and repair. We found that SERCA2a and SUMO1 levels were both reduced in models of heart failure and in failing human myocardium. We showed that increasing SUMO1 levels led to improved hemodynamic performance and reduced mortality in a murine model of HF. We now propose to further characterize the molecular mechanisms of SUMO1 in regulating SERCA2a function and to evaluate the multiple pathways regulating SUMOylation of SERCA2a.