Impaired Protein Degradation Pathways in Cardiac Proteinopathy

描述（由申请人提供）：CryAB（CryABR 120 G）中的Arg 120 Gly突变可引起结蛋白相关心肌病（DRM），其特征在于聚集的结蛋白和CryAB在心肌细胞的肌浆中积聚，导致转基因（TG）小鼠模型中的心肌病和过早死亡。我们的实验室已经鉴定出由CryABR 120 G突变形成的细胞内包涵体为侵袭体，其具有与在许多神经退行性疾病中观察到的蛋白质聚集体相似的形态学特征。事实上，CryABR 120 G TG小鼠含有淀粉样蛋白，其被靶向细胞毒性前淀粉样蛋白寡聚体（PAO）构象的抗体阳性染色，表明DRM是一种心脏蛋白构象疾病，其可能在许多形式的人类心力衰竭中普遍存在。数据表明，聚集表型是由降解错误折叠蛋白的正常机制中的功能缺陷部分引起的。这项研究的目的是验证一个假设，即恢复蛋白质降解途径中的功能缺陷可以在基于CryABR 120 G的心肌病中起到保护作用，从而减少聚集体形成并改善心脏功能。我们提出了两个具体的目标来测试蛋白质降解途径的调节组分如何影响基于CryABR 120 G的DRM中的异常蛋白质聚集：1）通过脑啡肽酶去除/降解PAO，脑啡肽酶是一种在类似疾病中显示降解可溶性低聚物的蛋白质，将对CryABR 120 G发病机制产生有利影响，以及2）通过减少蛋白质向受损降解区室的运输（通过降低辅伴侣蛋白/E3泛素连接酶CHIP的水平来实现），我们可以通过减少错误折叠蛋白的流入来维持或甚至恢复这些区室的降解能力，这将减少蛋白质积累和毒性。拟议的研究将确定CryABR 120 G中的蛋白质聚集是否是由心脏中蛋白质降解机制的缺陷引起的，更重要的是，确定这些途径的遗传调节是否可以在我们的模型中起到保护作用。了解蛋白质构象疾病中功能失调降解所起的作用可能会导致靶向治疗，以预防或延迟毒性蛋白质聚集体的发生，并可能广泛适用于心脏和其他组织中的许多类似疾病表型。 公共卫生相关性：许多心脏和大脑疾病是由于蛋白质错误折叠，导致变性和细胞死亡。我将研究两个基因，脑啡肽酶和CHIP，已知可以去除有毒的错误折叠蛋白质，这可能会延迟或预防心脏病。改善蛋白质去除可能为治疗退行性疾病提供一种治疗途径。

DESCRIPTION (provided by applicant): Arg120Gly mutations in CryAB (CryABR120G) can cause desmin-related cardiomyopathy (DRM), which is characterized by accumulation of aggregated desmin and CryAB in the sarcoplasm of cardiomyocytes, leading to cardiomyopathy and premature death in transgenic (TG) mouse models. Our lab has identified the intracellular inclusion bodies formed by CryABR120G mutations as aggresomes, which have similar morphological features to the protein aggregates observed in many neurodegenerative diseases. Indeed, CryABR120G TG mice contain amyloid-like proteins that are positively stained with an antibody targeting the conformation of a cytotoxic pre-amyloid oligomer (PAO), suggesting that DRM is a cardiac protein conformation disease which may be prevalent in many forms of human heart failure. Data suggests that the aggregation phenotype is caused, in part, by functional defects in the normal mechanisms of degrading misfolded proteins. The goal of the proposed research is to test the hypothesis that restoring functional deficits in protein degradation pathways can be protective in CryABR120G-based cardiomyopathy, leading to a reduction in aggregate formation and improved heart function. We have proposed two specific aims to test how modulating components of protein degradation routes can affect aberrant protein aggregation in CryABR120G-based DRM: 1) PAO removal/degradation by neprilysin, a protein shown to degrade soluble oligomers in similar diseases, will impact favorably on CryABR120G pathogenesis and 2) By decreasing protein traffic towards impaired degradation compartments (achieved by reducing the level of the cochaperone/E3 ubiquitin ligase CHIP), we can maintain or even restore the degradation capacity of these compartments by reducing the influx of misfolded protein, which will reduce protein accumulation and toxicity. The proposed studies will determine if protein aggregation in CryABR120G is caused by deficits in protein degradation machinery in the heart and, more importantly, determine if genetic modulation of these pathways can be protective in our model. Understanding the role played by malfunctioning degradation in protein conformation diseases could lead to targeted therapeutics to prevent or delay the onset of toxic protein aggregates, and may be widely applicable to a host of similar disease phenotypes in the heart and other tissues. PUBLIC HEALTH RELEVANCE: Many diseases of the heart and brain are due to protein misfolding, which causes degeneration and cell death. I will study two genes, neprilysin and CHIP, known to remove toxic misfolded proteins, which may delay or prevent heart disease. Improving protein removal may offer a therapeutic avenue to treat degenerative diseases.