Novel MYBPC1 mutations cosegregate with a myopathy associated with muscle weakness, hypotonia and tremor

新型 MYBPC1 突变与肌无力、肌张力减退和震颤相关的肌病共分离

基本信息

批准号：
10693128
负责人：
Aikaterini Kontrogianni-Konstantopoulos
金额：
$ 41.2万
依托单位：
UNIVERSITY OF MARYLAND BALTIMORE
依托单位国家：
美国
项目类别：
财政年份：
2020
资助国家：
美国
起止时间：
2020-09-01 至 2025-08-31
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10693128
关键词：
ATP phosphohydrolase Actins Actomyosin Adult Affect Alternative Splicing Animal Model Animals Architecture Arthrogryposis Atomic Force Microscopy Behavioral Behavioral Assay Benchmarking Binding Biochemical Biological Assay Biology Birth CRISPR/Cas technology Cardiac Cessation of life Circular Dichroism Clinical Research Cyclic AMP-Dependent Protein Kinases Deformity Development Disease Distal Electrostatics Etiology Evaluation Exhibits Face Family Fiber Filament Frequencies Gender Genes Goals Heart Diseases Heterozygote Hypertrophic Cardiomyopathy Impairment In Vitro Individual Knock-in Knock-in Mouse Life Light Link Maintenance Measurement Mediating Microfilaments Missense Mutation Modeling Molecular Morphology Movement Mus Muscle Muscle Tremors Muscle Weakness Muscle hypotonia Mutation Myocardium Myopathy Myosin ATPase N-terminal Pacemakers Pathogenesis Patients Performance Phenotype Phosphorylation Pilot Projects Posture Pre-Clinical Model Prevalence Process Production Protein Isoforms Proteins RNA Splicing Regulation Rest Role Science Skeletal Muscle Slide Striated Muscles Structure Symptoms Testing Thick Thick Filament Thin Filament Thinness Tremor Variant behavioral study biophysical properties cell motility comparative design disease diagnosis effective therapy experimental study in vitro activity in vivo mechanical properties molecular dynamics molecular modeling mouse model mutant myosin-binding protein C novel postnatal postnatal development reduced muscle strength segregation skeletal therapeutically effective therapy design

项目摘要

Abstract Myosin Binding Protein-C (MyBP-C) comprises a family of accessory proteins that directly interact with both thick myosin and thin actin filaments. Three distinct isoforms have been characterized, including the cardiac (c), slow (s) skeletal and fast (f) skeletal. During the last forty years, numerous studies have focused on the biology of cMyBP-C primarily due to its high mutational prevalence in heart disease. On the contrary, the regulation and roles of the skeletal isoforms have been mainly inferred due to the structural similarity they share with cMyBP-C. Our group has been studying the biology of sMyBP-C aiming to understand its regulation, roles, and disease association. Our findings are highly novel and intriguing. First, we found that MYBPC1, the gene that encodes sMyBP-C, is heavily spliced giving rise to multiple variants that can be co-expressed in the same muscle and myofiber. Second, the presence of alternatively spliced insertions affects the ability of the NH2 and COOH termini to bind actin and myosin, and regulate the formation of actomyosin crossbridges in vitro. Third, the NH2-terminus of sMyBP-C undergoes extensive PKA- and PKC-mediated phosphorylation, which is altered in disease. Fourth, sMyBP-C has both structural and regulatory roles with its structural role in the organization and maintenance of thick myosin filaments preceding its regulatory role in modulating cross- bridge cycling. Fifth, four novel, dominant, missense mutations located in the NH2-terminal M-motif of sMyBP-C co-segregate with of a new myopathy characterized by muscle weakness, hypotonia, facial and body deformities, and high-frequency irregular tremor. Molecular modeling and biochemical studies indicated that the four myopathic mutations differentially affect the ability of the NH2-terminus of sMyBP-C to bind myosin, and the structure and stability of the M-motif. We therefore hypothesize that the four MYBPC1 mutations may differentially alter the biochemical and biophysical properties of sMyBP-C compromising its structural and regulatory roles, yet elicit similar myopathic phenotypes. We further propose that mutant sMyBP-C results in the formation of abnormal and deregulated cross-bridges, which in addition to causing a deficit in force production underlying muscle weakness, act as the primary pacemaker of the observed tremor. The goal of our proposal is to comprehensively study the pathogenesis of this novel form of MYBPC1-associated myopathy using a combination of sophisticated in vitro approaches (Aim 1) and novel preclinical models (Aims 2 & 3). The proposed studies are highly significant in terms of discovery science as we will mechanistically examine the etiologies of this myopathy, and impactful in terms of translational/clinical research for accurate disease diagnosis as well as appropriate and effective treatment design.

抽象的肌球蛋白结合蛋白-C（MYBP-C）包括直接与之相互作用的辅助蛋白家族浓稠的肌球蛋白和薄肌动蛋白丝。已经表征了三种不同的同工型，包括心脏（C），慢速（S）骨骼和快速（F）骨骼。在过去的四十年中，许多研究集中在 CMYBP-C的生物学主要是由于其在心脏病中的高突变率。相反，由于结构相似性，骨骼同工型的调节和作用主要是推断与CMYBP-C分享。我们的小组一直在研究SMYBP-C的生物学，以了解其调节，角色和疾病协会。我们的发现非常新颖，有趣。首先，我们发现MyBPC1，编码smybp-c的基因被大量剪接产生到可以共表达的多种变体相同的肌肉和肌纤维。其次，剪接插入的存在会影响 NH2和COOH末端结合肌动蛋白和肌球蛋白，并调节Actomyosin Crossbridges在体外。第三，SMYBP-C的NH2末端经历了广泛的PKA和PKC介导的磷酸化，疾病改变了。第四，SMYBP-C具有结构和调节作用，其结构作用在调节交叉方面的调节作用之前的组织和维持厚的肌球蛋白细丝桥骑自行车。第五，四个小说，主导的错义突变与以肌肉无力，性低下，面部和身体为特征的新的肌病共隔离畸形和高频不规则震颤。分子建模和生化研究表明四个肌性突变差异地影响了SMYBP-C结合肌球蛋白的NH2末端的能力，以及m-motif的结构和稳定性。因此，我们假设这四个MyBPC1突变可能差异改变了SMYBP-C的生化和生物物理特性，从而损害其结构和监管角色，但引起类似的肌病表型。我们进一步提出突变体Smybp-C导致异常和放松管制的跨桥的形成，除了导致力不足之外产生肌肉无力的产生，充当观察到的震颤的主要起搏器。我们的目标建议是全面研究这种新型MYBPC1相关肌病的发病机理结合精致的体外方法（AIM 1）和新型的临床前模型（AIM 2＆3）。提出的研究在发现科学方面非常重要，因为我们将机械学检查这种肌病的病因，并且在精确疾病的转化/临床研究方面有影响诊断以及适当有效的治疗设计。