Molecular Mechanisms of Neuronal-dependent Muscle Plasticity

描述（由申请人提供）：目前修复退行性疾病、遗传病、衰老或创伤所致骨骼肌损伤或衰竭的两个挑战是：1）推进我们对成熟肌细胞表型如何维持的理解，以及2）识别和修饰与肌肉特性变化相关的神经依赖性过程。应对这些挑战将对针对肌肉功能受损患者的治疗方法的发展产生重要影响。电鱼Sternopygus macrurus是一种功能强大的脊椎动物模型系统，可以帮助阐明影响肌肉程序不同功能的细胞和分子机制。In S.在巨尾肌中，一些骨骼肌纤维完全分化，仅经历融合和随后在其形态和生化性质上的极端修饰，以转化成称为电细胞的非收缩性生电细胞。成熟的电细胞通过继续表达一些但不是所有的肌肉特异性蛋白质来保留部分肌肉表型。电细胞中选择肌肉基因表达的抑制依赖于连续的高频电激活模式。此外，电细胞中的这种缺乏肌肉表型在神经活动模式改变时是可逆的。初步数据加强了我们的目标，以确定参与介导的活动依赖性骨骼肌程序的重塑的分子过程。具体来说，我们将测试的假设，即介导神经活动依赖性调节骨骼肌肌肉基因的转录机制不同，在S。巨尾。该建议的具体目标是：1）确定骨骼肌和电细胞中的转录谱; 2）表征钙调神经磷酸酶/NFAT信号通路在介导电细胞中肌肉程序的神经依赖性调节中的作用;以及3）鉴定肌细胞与电细胞中由肌源性转录因子调节的基因。为确保建议的研究能顺利完成，我们已确立S。他使用一系列分子和细胞工具将macrurus应用于体内实验，并组建了一个研究团队，该团队拥有强大的导师支持以及神经肌肉生物学方面的互补技能和知识。这项研究有望提高我们对神经输入控制肌源性基因表达和肌肉表型维持的过程的理解-对肌肉功能的理解对人类肌肉疾病的治疗方法具有重要意义。 公共卫生相关性：最佳骨骼肌性能对于生物体健康的意义是深远的，并且由神经和肌肉退行性疾病、创伤、遗传条件和衰老引起的肌肉组织功能的失效是现代医学最普遍的问题之一。该提案使用了一个创新的模型系统来探索神经诱导的电活动对肌肉细胞可塑性的影响：脊椎动物鱼，其中骨骼肌程序的特定功能可以通过神经输入的变化来抑制，并导致肌肉转化为非收缩细胞。这项研究有望增强我们对调节肌肉特性的维持和可塑性的细胞和分子过程的理解-对肌肉功能的理解对人类肌肉疾病的治疗方法具有重要意义。

DESCRIPTION (provided by applicant): Two current challenges in the repair of skeletal muscle injury or failure due to degenerative disease, genetic conditions, aging, or trauma are: 1) advancing our understanding of how the mature muscle cell phenotype is maintained, and 2) identification and modification of nerve-dependent processes that are coupled to changes in muscle properties. Meeting these challenges will have critical implications for development of therapies directed toward patients with impaired muscle function. The electric fish Sternopygus macrurus is a powerful vertebrate model system that can help elucidate cellular and molecular mechanisms that affect different features of the muscle program. In S. macrurus, some skeletal muscle fibers fully differentiate only to undergo fusion and subsequent extreme modifications in their morphological and biochemical properties to convert into non-contractile electrogenic cells called electrocytes. Mature electrocytes retain a partial muscle phenotype by continuing to express some, but not all muscle-specific proteins. The suppression of select muscle gene expression in electrocytes is dependent on a continuous, high frequency electrical activation pattern. Further, this deficient muscle phenotype in electrocytes is reversible upon changes in nerve activity patterns. Preliminary data intensified our goal to identify the molecular processes involved in mediating the activity-dependent remodeling of the skeletal muscle program. Specifically, we will test the hypothesis that the transcriptional mechanisms that mediate neural activity-dependent regulation of muscle genes in skeletal muscle differ in electrocytes of S. macrurus. The specific aims of this proposal are: 1) to determine the transcript profiles in skeletal muscle and electrocytes; 2) to characterize the role of the calcineurin/NFAT signaling pathway in mediating the neural-dependent regulation of the muscle program in electrocytes, and 3) to identify the genes regulated by myogenic transcription factors in muscle cells versus electrocytes. To ensure the successful completion of the studies proposed, we have established the amenability of S. macrurus to in vivo experimentation using a collection of molecular and cellular tools, and assembled a research team with strong mentorship support and complementary skills and knowledge in neuromuscular biology. This research is expected to enhance our understanding of the processes by which neural input controls myogenic gene expression and maintenance of the muscle phenotype - an understanding of muscle function with critical implications to therapeutic approaches for human muscle diseases. PUBLIC HEALTH RELEVANCE: The significance of optimal skeletal muscle performance for the health of living organisms is profound, and failure of muscle tissue function that results from nerve and muscle degenerative diseases, trauma, genetic conditions, and aging is among the most universal problems of modern medicine. This proposal uses an innovative model system to explore the effects of nerve-induced electrical activity on muscle cell plasticity: a vertebrate fish wherein specific features of the skeletal muscle program can be suppressed by changes in neural input and lead to the transformation of muscle into non-contractile cells. This research is expected to enhance our understanding of the cellular and molecular processes that regulate the maintenance and plasticity of muscle properties - an understanding of muscle function with critical implications to therapeutic approaches for human muscle diseases.