Wrestling stress: role of ufm1 modification in pathological cardiac remodeling

项目总结 泛素和类泛素蛋白的蛋白质翻译后修饰是重要的机制 调节对心肌细胞功能和动态平衡不可或缺的蛋白质质量和功能。整体而言 这项提议的目的是确定一种新的泛素样蛋白的功能和潜在机制， 泛素折叠修饰物1(Ufm1)，在心脏。Ufm1通过Ufm1与靶底物发生共价偶联 Ufm1特异性的E1(Uba5)-E2(Ufc1)-E3(Ufl1)级联。通过调节细胞蛋白质的功能， Ufmylation控制着多种细胞过程和生理事件，并与许多 人类疾病。我们的初步研究首次确定了超甲基化在抑制中的关键作用。 病理性心脏重塑和提供ufm化和内质之间新的机制联系 网状结构(ER)应激反应。Ufmylating在心肌病心脏中处于失调状态。抑制ufmyl化 通过靶向消融心脏中的E3Ufm1连接酶1(Ufl1)在衰老和死亡期间引起心肌病 增加对血流动力学应激反应的心力衰竭倾向。内质网应激与 这些小鼠心肌病的进展，以及内质网应激的药物缓解改善心脏 Ufl1缺陷心脏的压力超负荷后的功能障碍。此外，Ufl1还控制着 Ufm1结合蛋白1(Ufbp1)，内质网驻留的Ufm1靶标。Ufbp1的耗尽减少了XBP-1的剪接， 钝化XBP-1s信号并加重内质网应激诱导的细胞损伤，概括了Ufl1的大部分方面 耗尽。此外，内质网应激促进Ufbp1与Ire 1α的结合，Ire 1是一个关键的内质网应激转导因子， 激活心脏保护性XBP-1s信号。这些数据共同表明，Ufbp1在Ufl1下游起作用 保护CMS免受病原性损伤，是心肌细胞IRE1a/XBP-1s信号的重要调节因子。 因此，这一建议是为了验证ufm化预防病理性心脏重塑的假设。 通过靶向Ufbp1激活心肌细胞适应性内质网应激反应。要检验这一假设，目标是 1将定义Ufbp1在心脏中的病理生理作用；目标2将确定分子基础如何 超甲基化激活心肌细胞内适应性内质网应激反应信号；Aim 3将阐明 Ufbp1超甲基化在激活IRE1a/XBP-1s信号通路和限制细胞损伤中的作用 对压力的反应。这项拟议的研究是首次在心力衰竭模型中靶向蛋白质ufm化和 将使用独特的工具，包括三个新的基因工程小鼠模型，以提供翻译 意义。该项目的完成将确立翻译后修饰(Ufmylating)的新作用。 在心脏功能调节中的作用和在心脏治疗中开发新的分子靶点 疾病。

PROJECT SUMMARY Protein post-translational modifications by ubiquitin and ubiquitin-like proteins represent vital mechanisms regulating protein quality and function that are integral to cardiomyocyte function and homeostasis. The overall goal of this proposal is to determine the function and underlying mechanism of a novel ubiquitin-like protein, Ubiquitin-fold modifier 1 (Ufm1), in the heart. Ufmylation covalently conjugates Ufm1 to target substrates via a Ufm1-specific E1 (Uba5)-E2 (Ufc1)-E3 (Ufl1) cascade. Through regulating the function of cellular proteins, ufmylation controls multiple cellular processes and physiological events, and have been implicated in a number of human diseases. Our pilot studies have for the first time identified a critical role for ufmylation in constraining pathological cardiac remodeling and provided novel mechanistic linkages between ufmylation and endoplasmic reticulum (ER) stress response. Ufmylation is dysregulated in cardiomyopathic hearts. Inhibition of ufmylation via targeted ablation of the E3 Ufm1 ligase 1 (Ufl1) in the heart caused cardiomyopathy during ageing and promoted propensity to heart failure in response to hemodynamic stress. ER stress coincided with the progression of cardiomyopathy in these mice, and pharmacological attenuation of ER stress ameliorated cardiac dysfunction following pressure overload in Ufl1-deficient hearts. Furthermore, Ufl1 controls the expression of Ufm1 binding protein 1 (Ufbp1), an ER-resident Ufm1 target. Depletion of Ufbp1 diminished Xbp-1 splicing, blunted Xbp-1s signaling and aggravated ER stress-induced cell injury, recapitulating most aspects of Ufl1 depletion. Moreover, ER stress promotes the binding of Ufbp1 to IRE1α, a key ER stress transducer that activates cardioprotective Xbp-1s signaling. These data collectively suggest that Ufbp1 acts downstream of Ufl1 to protect CMs against pathogenic insults and is a crucial regulator of IRE1a/Xbp-1s signaling in cardiomyocytes. Therefore, this proposal is to test the hypothesis that ufmylation protects against pathological cardiac remodeling by targeting Ufbp1 to activate the adaptive ER stress response in cardiomyocytes. To test this hypothesis, Aim 1 will define the pathophysiological roles of Ufbp1 in the heart; Aim 2 will identify molecular bases of how ufmylation activates the adaptive ER stress response signaling in cardiomyocytes; Aim 3 will elucidate the functional importance of Ufbp1 ufmylation in activating IRE1a/Xbp-1s signaling and limiting cellular damage in response to stress. The proposed study is the first to target protein ufmylation in a model of cardiac failure and will employ unique tools including three new genetically-engineered mouse models to provide translational significance. Completion of this project will establish a novel role of post-translational modification (ufmylation) in the regulation of cardiac function and suggest new molecular targets for exploitation in the treatment of heart disease.