The role of Hsp70 chaperones in MYBPC3-linked hypertrophic cardiomyopathy

Hsp70 伴侣在 MYBPC3 相关肥厚型心肌病中的作用

• 批准号: 9540919
• 负责人: Amelia Ann Glazier
• 金额: $ 1.19万
• 依托单位: UNIVERSITY OF MICHIGAN AT ANN ARBOR
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-09-01 至 2018-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9540919
• 关键词: Address; Adenoviruses; Affect; Animal Model; Area; Binding; Biochemical; Biological Assay; Biological Models; Cardiac; Cardiac Myocytes; Cardiac Myosins; Cell Culture Techniques; Cell model; Cells; Cellular Morphology; Client; Complex; Cycloheximide; Data; Development; Disease; Familial Hypertrophic Cardiomyopathy; Family; Fibrosis; Flow Cytometry; Frequencies; Functional disorder; Genes; Genetic; Goals; Health; Heart Diseases; Heat shock proteins; Heat-Shock Response; Human; Hypertrophic Cardiomyopathy; Hypertrophy; Impairment; In Situ Nick-End Labeling; Inherited; Knock-out; Left ventricular structure; Light; Link; Luciferases; Molecular; Molecular Chaperones; Morphology; Mus; Mutation; Myocardial; Myocardial tissue; Myocardium; Neonatal; Nonsense Mutation; Pathogenesis; Pathogenicity; Phenotype; Physiology; Play; Pluripotent Stem Cells; Protein Family; Protein Isoforms; Proteins; Publishing; Quality Control; Rattus; Research Training; Role; Sampling; Sarcomeres; Small Interfering RNA; Stains; System; Testing; Transcript; Transgenic Mice; Triage; Ubiquitin; Ubiquitination; Ventricular; Western Blotting; Whole Organism; Work; YM1 doxorubicin analog; analog; base; experimental study; innovation; multicatalytic endopeptidase complex; mutant; myosin-binding protein C; new therapeutic target; overexpression; proteostasis; proteotoxicity; public health relevance; response; small molecule

 DESCRIPTION (provided by applicant): Hypertrophic cardiomyopathy (HCM), characterized by hypertrophy and fibrosis of the left ventricle (LV) and septum, is the most common inherited heart disease. The gene MYBPC3 encoding cardiac myosin binding protein C (cMyBPC) accounts for approximately 40-50% of cases in which causative mutations are identified. Of special note is the high frequency of nonsense mutations resulting in truncated proteins in MYBPC3 relative to other HCM-linked genes. The most prevalent hypothesis for the primary disease mechanism in these cases is inadequate sarcomeric wild-type cMyBPC expression. However, such haploinsufficiency of cMyBPC has yet to be satisfactorily demonstrated, and the Day lab has published data from a large sampling of human HCM myocardial tissue suggesting this is not the case. Growing evidence, supported by findings of ubiquitin proteasome system (UPS) dysfunction in cell and animal models expressing truncated cMyBPC as well as in human HCM, indicates protein quality control (PQC) mechanisms play an important role. Cardiac PQC is an area of undervalued potential in which further elucidation of the complex pathogenesis of HCM may be made. Chaperone proteins are crucial to proper PQC, but little is known about their effects on myocardial physiology. Experimentally, knockout of inducible Hsp70 and its cochaperone Hspa4 both caused LV hypertrophy in mice. This research training plan will investigate a potential link between UPS dysfunction and interactions of truncated cMyBPC with the Hsp70 family of chaperones. The main hypothesis is that UPS dysfunction and proteotoxicity in cardiomyocytes expressing truncated cMyBPC can be alleviated by clearance of the mutant proteins via the protein triaging activity of Hsp70 chaperones. The specific aims of this proposal are to define physical and functional interactions between mutant cMyBPC and the Hsp70 family of chaperones and to determine the effects of promoting cMyBPC degradation by modulating Hsp70 activity or expression on UPS dysfunction and proteotoxicity in cardiomyocytes. These aims will be accomplished using a complementary battery of biochemical, cellular, and whole organism assays performed in both established and innovative new cell culture and animal models of HCM.

 描述(申请人提供)：肥厚性心肌病(HCM)是最常见的遗传性心脏病，以左心室(LV)和室间隔肥大和纤维化为特征。编码心肌肌球蛋白结合蛋白C(CMyBPC)的MYBPC3基因约占致病突变病例的40%-50%。特别值得注意的是，相对于其他HCM连锁基因，MYBPC3中导致截断蛋白的无义突变的频率很高。对于这些病例的主要发病机制，最普遍的假说是肌瘤野生型cMyBPC表达不足。然而，cMyBPC的这种单倍性不足还没有得到令人满意的证明，Day实验室已经公布了大量人类HCM心肌组织样本的数据，表明情况并非如此。越来越多的证据表明，在表达截短cMyBPC的细胞和动物模型中以及在人类HCM中，泛素蛋白酶体系统(UPS)功能障碍的发现表明，蛋白质质量控制(PQC)机制发挥了重要作用。心脏PQC是一个被低估的潜在领域，可能会进一步阐明HCM的复杂发病机制。伴侣蛋白对正常的PQC至关重要，但对其对心肌生理学的影响知之甚少。在实验上，可诱导的Hsp70及其辅伴侣Hspa4的敲除都会导致小鼠左室肥厚。这项研究培训计划将调查UPS功能障碍与截短的cMyBPC与Hsp70家族伴侣之间的相互作用之间的潜在联系。主要的假设是，通过Hsp70伴侣蛋白的蛋白分流活性清除突变蛋白，可以减轻表达截短cMyBPC的心肌细胞的UPS功能障碍和蛋白毒性。本研究的具体目的是确定突变型cMyBPC和Hsp70伴侣蛋白家族之间的物理和功能相互作用，并确定通过调节Hsp70的活性或表达来促进cMyBPC降解对心肌细胞UPS功能障碍和蛋白毒性的影响。这些目标将通过在已建立的和创新的HCM新细胞培养和动物模型中进行的生化、细胞和整体分析的补充电池来实现。