Mechanisms Regulating Myoblast Fusion in Drosophila

描述（由申请人提供）：我们建议增加一个额外的目标，通过在果蝇和小鼠C2C12成肌细胞组织培养两种模型系统中利用方法的协同作用来扩大母体资助的范围并提高研究速度，以发现驱动成肌细胞融合的基本机制。它还将允许我的实验室保留两名关键人员，他们的外部资金将于2009年6月到期。肌肉萎缩的衰弱性发作，影响行动能力和生活质量，是一个日益严重的公共卫生问题。肌肉萎缩是肌肉萎缩症等疾病的结果，是癌症化疗的副作用，也是衰老的标志。由于修复受损骨骼肌的正常途径涉及卫星细胞与受损肌管的融合，因此开发治疗方法的重要一步将是了解调节成肌细胞融合的基因和机制。我们的长期目标是了解基本的、保守的基因和驱动成肌细胞融合的机制。我们的中心假设是，特定的细胞骨架重排是所有成肌细胞融合的关键。我们在卫星细胞衍生的C2C12小鼠成肌细胞培养系统中获得的初步结果表明，融合机制的某些元素在物种间是保守的：敲除5个苍蝇融合基因的哺乳动物同源物显示C2C12成肌细胞中存在成肌细胞融合表型。在这些强有力的初步结果的指导下，我们假设我们在果蝇中定义的基于肌动蛋白的活动和肌动蛋白调节因子的范例适用于哺乳动物系统。为了验证这一假设，在目标4A中，我们将使用我们开发的分析方法来分析哺乳动物同源物的这一子集，以定义这些敲低谱系中融合过程的哪些方面是异常的。在目标4B中，我们将确定苍蝇融合基因的其他同源物以及其他肌动蛋白调节因子是否同样影响融合。我们的工作意义重大，因为它有望揭示细胞-细胞融合的基本细胞和分子机制。拟议的研究与公共卫生相关，因为一旦分子参与者及其作用的细胞靶点被确定或理解，就可以开发旨在调节成肌细胞融合的疗法，以促进融合，以治疗因衰老或疾病引起的肌肉萎缩。

DESCRIPTION (provided by applicant): We propose to add an additional aim that will expand the scope of the parent grant and increase the tempo of research by exploiting the synergy of approaches in two model systems, Drosophila and mouse C2C12 myoblast tissue culture to find basic mechanisms driving myoblast fusion. It will also allow the retention of two key personnel in my laboratory, whose outside funding will lapse in June 2009. The debilitating onset of muscle wasting, which affects mobility and quality of life, is an ever- growing problem in public health. Muscle wasting is the result of diseases such as muscular dystrophy, a side effect of chemotherapy for cancers and a hallmark of aging. Since the normal pathway to repair damaged skeletal muscles involves the fusion of satellite cells to damaged myotubes, an important step in developing treatments will be to understand the genes and mechanisms that regulate myoblast fusion. Our long-term goal is to understand essential, conserved genes and mechanisms driving myoblast fusion. Our central hypothesis in our proposal is that specific cytoskeletal rearrangements are critical for all myoblast fusions. Our strong preliminary results in the satellite cell-derived C2C12 mouse myoblast culture system indicate that certain elements of the fusion machinery are conserved across species: knockdown of 5 mammalian homologs of fly fusion genes show a myoblast fusion phenotype in C2C12 myoblasts. Guided by these strong preliminary results, we hypothesize that the paradigm of actin based activities and actin regulators that we have defined in Drosophila apply in a mammalian system. To test this hypothesis, in aim 4A, we will analyze this subset of mammalian homologs using assays that we have developed to define what aspects of the fusion process are aberrant in these knockdown lines. In aim 4B, we will determine if other homologs of fly fusion genes and if other actin regulators similarly affect fusion. Our work is significant because it is expected to reveal the essential cellular and molecular mechanisms underlying cell-cell fusion. The proposed research is relevant to public health because once the molecular players and the cellular targets of their action are identified or understood, therapies designed to regulate myoblast fusion can be developed to promote fusion for the treatment of muscle wasting due to aging or disease. PUBLIC HEALTH RELEVANCE: Critical to our understanding of muscle disease is the identification of genes and mechanisms underlying myoblast fusion. An essential model of myoblast fusion will be developed using the strengths of two model systems, Drosophila and the mouse C2C12 myoblasts.