The Role of Germline Mutations of the Ras/MAPK Pathway on Skeletal Myogenesis

Ras/MAPK 途径种系突变对骨骼肌生成的作用

• 批准号: 8716527
• 负责人: Katherine Anna Rauen
• 金额: $ 34.31万
• 依托单位: UNIVERSITY OF CALIFORNIA AT DAVIS
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-01-01 至 2018-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8716527
• 关键词: Address; Affect; BRAF gene; Cell Cycle; Cell physiology; Costello syndrome; Cutaneous; Data; Development; Effectiveness; Exhibits; Feedback; Foundations; Functional disorder; Genes; Genetic; Germ-Line Mutation; Goals; Growth; HRAS gene; Histopathology; In Vitro; Individual; Knowledge; LEOPARD Syndrome; MAP2K1 gene; MAPK14 gene; Malignant Neoplasms; Mediating; Medical Genetics; Mitogen-Activated Protein Kinases; Modeling; Morbidity - disease rate; Muscle; Muscle Development; Muscle Fibers; Muscle Weakness; Muscle hypotonia; Mutation; Myoblasts; Myopathy; Nerve; Neurofibromatosis 1; Noonan Syndrome; Pathology; Pathway interactions; Patients; Phenotype; Play; Process; Proliferating; Publishing; Regulation; Research; Role; Signal Pathway; Signal Transduction; Skeletal Muscle; Small Interfering RNA; Staging; Syndrome; System; Testing; Therapeutic Intervention; Tissues; base; congenital anomaly; design; human MAPK14 protein; in vivo; in vivo Model; inhibitor/antagonist; insight; mouse model; muscle form; myogenesis; novel; patient population; research study; skeletal; small molecule

DESCRIPTION (provided by applicant): Skeletal myogenesis is a dynamic process in which muscle precursor cells first proliferate and then fuse to form multinucleated myotubes that ultimately mature into skeletal muscle fibers. The Ras/Mitogen-activated protein kinase (MAPK) pathway, a well-studied cancer pathway, plays a critical role in the regulation of myogenesis, particularly during the switch from myoblast proliferation to differentiation. Early studies have demonstrated that high levels of Ras/MAPK pathway activation disrupt early myogenesis. However, there are critical gaps in our understanding as to how Ras and its downstream effector cascades regulate and affect vital steps in myogenesis during development. The "RASopathies", a newly defined group of medical genetic syndromes, are one of the largest groups of multiple congenital anomaly syndromes known, affecting more than 1 in 1000 individuals. Caused by germline mutations in various key genes encoding components of the Ras/MAPK pathway, the RASopathies share a common phenotypic feature of congenital hypotonia, or weak muscles. Costello syndrome (CS) and cardio-facio-cutaneous (CFC) syndrome are two RASopathies with the most severe muscle phenotype. We have recently identified the presence of a novel myopathy, defined as an intrinsic abnormality of muscle that is not attributable to nerve dysfunction, in individuals with CS and CFC. In addition, our preliminary studies provide support for our hypothesis that dysregulation of Ras/MAPK signaling disrupts both early myogenesis by inhibiting myoblast differentiation, and later stages of muscle development following differentiation, by inhibiting muscle growth. The goal of the proposed research is to understand how myogenesis is affected by Ras/MAPK dysregulation, as well as the specific mechanism of action underlying this effect. We will examine novel germline mutations identified in the RASopathies to help us understand how Ras dysregulation affects muscle development. Our Specific Aims are designed to determine 1) how skeletal muscle is disrupted by dysregulation of Ras/MAPK pathway signaling in CS and CFC; 2) the mechanisms by which Ras/MAPK dysregulation causes disruption of skeletal muscle myogenesis, and 3) if small molecule inhibitors and small interfering RNAs (siRNA) can reverse the effects of dysregulated Ras/MAPK signaling during myogenesis. We will use mouse models of CS and CFC to elucidate how skeletal muscle is disrupted by distinguishing what aspect of the myopathy is due to inhibition of myoblast differentiation and what is due to muscle fiber formation from post-differentiation inhibition of muscle growth. We will elucidate the specific mechanisms by which Ras/MAPK signal dysregulation inhibits myogenesis using primary myoblasts derived from CS and CFC mouse models. Results derived from those experiments will be used to evaluate the effectiveness of rationally chosen inhibitors to correct the developmental effects of a dysregulated Ras pathway using in vitro and in vivo models of myogenesis.

描述（由申请人提供）：骨骼肌发生是一个动态过程，其中肌肉前体细胞首先增殖，然后融合形成多核肌管，最终成熟为骨骼肌纤维。Ras/丝裂原活化蛋白激酶（MAPK）通路是一种研究充分的癌症通路，在肌生成的调节中起着关键作用，特别是在成肌细胞从增殖到分化的转换期间。早期的研究表明，高水平的Ras/MAPK通路激活会破坏早期肌生成。然而，我们对Ras及其下游效应级联如何调节和影响发育过程中肌生成的重要步骤的理解存在重大差距。“RASopathies”是一组新定义的医学遗传综合征，是已知的最大的多先天性异常综合征组之一，影响超过1/1000的个体。由于编码Ras/MAPK通路组分的各种关键基因的种系突变引起，RASopathies具有先天性肌张力减退或肌肉无力的共同表型特征。Costello综合征（CS）和心-面-皮肤（CFC）综合征是两种具有最严重肌肉表型的RASopathy。我们最近发现了一种新的肌病的存在，定义为一种内在的肌肉异常，是不是由于神经功能障碍，在个人与CS和CFC。此外，我们的初步 研究为我们的假设提供了支持，即Ras/MAPK信号传导的失调通过抑制成肌细胞分化而破坏早期肌发生，以及通过抑制肌肉生长而破坏分化后的肌肉发育的后期阶段。这项研究的目的是了解Ras/MAPK失调如何影响肌生成，以及这种影响背后的具体作用机制。我们将研究在RASopathies中发现的新的种系突变，以帮助我们了解Ras失调如何影响肌肉发育。我们的特定目的旨在确定1）CS和CFC中Ras/MAPK通路信号转导失调如何破坏骨骼肌; 2）Ras/MAPK失调导致骨骼肌肌发生中断的机制; 3）小分子抑制剂和小干扰RNA（siRNA）是否可以逆转肌发生期间Ras/MAPK信号转导失调的影响。我们将使用CS和CFC的小鼠模型来阐明骨骼肌是如何被破坏的，通过区分肌病的哪些方面是由于成肌细胞分化的抑制，哪些是由于肌肉生长的分化后抑制的肌纤维形成。我们将阐明具体的机制，Ras/MAPK信号失调抑制肌细胞来源于CS和CFC小鼠模型的原代成肌细胞的肌发生。来自这些实验的结果将用于评估合理选择的抑制剂的有效性，以纠正使用体外和体内肌生成模型的失调Ras途径的发育影响。