Wrestling stress: role of ufm1 modification in pathological cardiac remodeling

项目摘要 蛋白质翻译后修饰的泛素和泛素样蛋白代表了重要的机制 调节对心肌细胞功能和稳态不可或缺的蛋白质质量和功能。整体 该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（Ufm 1），在心脏中。Ufmylation通过共价键将Ufm 1结合到靶底物上， Ufm 1特异性E1（Uba 5）-E2（Ufc 1）-E3（Ufl 1）级联。通过调节细胞蛋白质的功能， 磺酰化控制多种细胞过程和生理事件，并且已经牵涉到许多生物学过程。 人类疾病。我们的初步研究首次确定了ufmylation在抑制细胞凋亡中的关键作用。 病理性心脏重塑，并提供了新的机制之间的联系， 内质网应激反应。在心肌病心脏中，Ufmylation失调。磺酰化的抑制 通过靶向消融心脏中的E3 Ufm 1连接酶1（Ufl 1），在衰老过程中引起心肌病， 促进对血流动力学应激的心力衰竭倾向。ER应力与 这些小鼠心肌病的进展，以及ER应激的药理学衰减改善了心脏 Ufl 1缺陷心脏压力超负荷后的功能障碍。此外，Ufl 1控制着 Ufm 1结合蛋白1（Ufbp 1），一种ER驻留的Ufm 1靶标。Ufbp 1的缺失减少了Xbp-1的剪接， 减弱Xbp-1 s信号传导，加重ER应激诱导的细胞损伤，概括了Ufl 1的大部分方面 耗尽此外，ER应激促进Ufbp 1与IRE 1 α的结合，IRE 1 α是一种关键的ER应激传感器， 激活心脏保护性Xbp-1 s信号。这些数据共同表明Ufbp 1作用于Ufl 1的下游 保护CM免受致病性损伤，并且是心肌细胞中IRE 1a/Xbp-1 s信号传导的关键调节剂。 因此，本研究的目的是验证ufmylation对病理性心脏重塑的保护作用这一假说 通过靶向Ufbp 1激活心肌细胞的适应性ER应激反应。为了验证这一假设， 目的1将定义Ufbp 1在心脏中的病理生理学作用;目的2将确定Ufbp 1如何在心脏中发挥作用的分子基础。 磺酰化激活心肌细胞中的适应性ER应激反应信号传导;目的3将阐明 Ufbp 1在激活IRE 1a/Xbp-1 s信号传导和限制细胞损伤中的功能重要性 对压力的反应。这项研究是第一个在心力衰竭模型中靶向蛋白质磺酰化的研究， 将采用独特的工具，包括三种新的基因工程小鼠模型， 意义该项目的完成将确立翻译后修饰（ufmylation）的新作用 在调节心脏功能方面的作用，并为心脏病的治疗提供了新的分子靶点 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.