CCDC78 and the pathogenesis of centronuclear myopathy

描述（由申请人提供）：中枢性肌病是一组儿童期发作的肌肉疾病，定义为共有的肌肉活检特征，特征为肌无力和严重运动残疾。目前，CNM有5种已知的遗传原因，最近对这些基因产物的研究已经确定异常兴奋-收缩偶联是疾病发病机制的关键方面。尽管取得了这些进展，但目前还没有针对CNM的治疗方法，关于这些临床上严重的疾病仍有许多有待了解的地方。大约40%的全国妇女理事会病例是遗传学未解决的。确定额外的遗传原因对于提高对这种疾病的认识和开发治疗方法至关重要。我们已经使用连锁分析和全外显子测序，以确定一个新的基因突变CCDC 78基因在一个家庭与常染色体显性遗传的CNM。CCDC 78编码一种以前未表征的基因产物，预测该基因突变会导致产生一种内部缺失的蛋白质。我们的假设是（a）野生型CCDC 78是肌肉发育所需的，特别是稳定兴奋-收缩偶联机制所需的，（B）突变型CCDC 78以显性负性方式起作用以隔离ECC蛋白，从而损害运动功能。这些假设将在两个目标进行测试。目的1将检查野生型CCDC 78的功能，目的2将测试CCDC 78突变对肌肉发育和功能的影响。这两个目标都将利用一种组合方法，包括体外研究、生物化学和蛋白质组学技术以及斑马鱼体内实验。特别是，该项目将利用 斑马鱼中操纵基因表达的能力，用于创建功能丧失和显性负性模型，以及实时图像分析，用于动态检查肌肉功能的特定特性。总之，这一提议将确定CCDC 78在肌肉发育中的功能以及其在CNM中突变的致病机制。这些数据将被放置在CNM的现有知识的背景下，允许在肌肉功能和这种毁灭性疾病的发病机制的理解的关键进展。 公共卫生相关性：中枢性肌病是一种常见的儿童肌肉疾病，与显著的发病率和早期死亡率相关，目前还没有治疗方法。虽然最近的研究已经提高了对这种情况的认识，但在开发治疗方法之前仍有许多问题需要了解。本提案的目的是通过确定CCDC 78的功能来提供对中枢性肌病的理解方面的进展，我们新发现CCDC 78突变是这种疾病的原因之一。

DESCRIPTION (provided by applicant): Centronuclear myopathies are a group of childhood onset muscle diseases defined by shared muscle biopsy features and characterized by muscle weakness and severe motor disability. Currently there are 5 known genetic causes for CNM, and recent studies on these gene products have identified abnormal excitation- contraction coupling as a key aspect of disease pathogenesis. Despite these advancements, no treatments current exist for CNMs and much remains to be understood about these clinically severe conditions. Approximately 40% of cases of CNM are genetic unresolved. Determination of additional genetic causes is critical to advance the knowledge of and to develop treatments for this disease. We have used linkage analysis and whole exome sequencing to identify a novel gene mutation in the CCDC78 gene in a family with autosomal dominant CNM. CCDC78 encodes a previously uncharacterized gene product, and the gene mutation is predicted to result in production of a protein with an internal deletion. Our hypotheses are that (a) wild type CCDC78 is required for muscle development and in particular for stabilizing the excitation-contraction coupling machinery and that (b) mutant CCDC78 functions in a dominant negative manner to sequester ECC proteins and thereby impair motor function. These hypotheses will be tested in two aims. Aim 1 will examine the function(s) of wild type CCDC78 and Aim 2 will test the impact of the CCDC78 mutation on muscle development and function. Both aims will utilize a combinatorial approach that includes in vitro studies, biochemical and proteomic techniques, and in vivo experimentation in the zebrafish. In particular, the project will take advantage of the power in the zebrafish for manipulation of gene expression, used to create both loss of function and dominant negative models, and live image analysis, used to dynamically examine specific properties of muscle function. In all, this proposal will determine the function of CCDC78 in muscle development as well as the pathogenic mechanisms underlying its mutation in CNM. These data will be placed in the context of the existing knowledge of CNM, allowing for critical advancements in the understanding of muscle function and the pathogenesis of this devastating disease. PUBLIC HEALTH RELEVANCE: Centronuclear myopathies are a common childhood muscle disease, associated with significant morbidity and early mortality, for which no treatments currently exist. While recent studies have advanced the knowledge of this condition, much remains to be understood before therapies can be developed. The goal of this proposal is to provide this advancement in understanding of centronuclear myopathy by determining the function of CCDC78, mutations in which we have newly identified as one cause of this disorder.