Mechanisms Regulating Myoblast Fusion in Drosophila

描述(申请人提供)：人类和果蝇的肌肉都是由成肌细胞融合产生的多核肌纤维组成的。然而，调控成肌细胞融合的事件和分子还不是很清楚。我们的长期目标是了解成肌细胞的融合，特别是对产生肌肉纤维所需的融合事件数量的调节。这项建议的目的是确定在模式生物黑腹果蝇中控制成肌细胞融合的关键细胞和分子机制。果蝇和哺乳动物在肌肉发育中的基因和机制的保守使我们能够使用更简单的果蝇系统来为治疗人类肌肉疾病以及因衰老和化疗而导致的肌肉萎缩做出相关发现。我们在这项提议中的中心假设是，特定的细胞骨架重排对成肌细胞融合至关重要。在我们强大的初步数据的指导下，这一假说将在三个具体目标上进行检验：(1)确定导致成肌细胞融合的关键细胞骨架重排；(2)确定已知融合基因在调节成肌细胞融合所需的特定细胞骨架行为中的需求；以及(3)确定新的融合基因在调节对成肌细胞融合至关重要的特定细胞骨架重排中的作用。在第一个目标下，我们开发了新的成像技术来识别活胚胎和固定胚胎中成肌细胞融合过程中的细胞骨架重排。我们的初步数据已经确定了几个这样重要的细胞骨架重排。在第二个目标下，我们将测试与这些细胞骨架重排相关的已知融合基因的影响。我们已经可以将特定基因的活动与特定的细胞骨架重排联系起来。在第三个目标下，我们将通过检测我们已经识别的新基因来研究融合过程中细胞骨架变化的机制。我们的工作意义重大，因为它有望揭示细胞-细胞融合背后的细胞和分子机制。这项拟议的研究与公共健康相关，因为一旦确定或了解了分子参与者和它们作用的细胞靶点，就可以开发旨在调节成肌细胞融合的疗法，以促进融合，用于治疗因衰老或疾病而导致的肌肉萎缩。

DESCRIPTION (provided by applicant): Muscles in both humans and Drosophila are composed of multinucleate myofibers that are generated by the fusion of myoblasts. However, the events and molecules that regulate myoblast fusion are not well understood. Our long-term goal is to understand myoblast fusion, and in particular, the regulation of the number of fusion events required to create a muscle fiber. The objective of this proposal is to determine the critical cellular and molecular mechanisms controlling myoblast fusion in the model organism, Drosophila melanogaster. The conservation of genes and mechanisms in muscle development between Drosophila and mammals allows us to use the simpler Drosophila system to make relevant discoveries for treatments of human muscular diseases and of muscle wasting due to aging and chemotherapies. Our central hypothesis in this proposal is that specific cytoskeletal rearrangements are critical for myoblast fusion. Guided by our strong preliminary data, this hypothesis will be tested in three specific aims: (1) Identify the critical cytoskeletal rearrangements that underlie myoblast fusion; (2) Determine the requirement of known fusion genes in regulating specific cytoskeletal behaviors underlying myoblast fusion; and (3) Identify the role of new fusion genes in regulating the specific cytoskeletal rearrangements critical for myoblast fusion. Under the first aim, we have developed novel imaging techniques to identify cytoskeletal rearrangements during myoblast fusion in living and fixed embryos. Our preliminary data has pinpointed several such important cytoskeletal rearrangements. Under the second aim, we will test the impact of known fusion genes in relationship to these cytoskeletal rearrangements. Already we can link specific genes' activities to specific cytoskeletal rearrangements. Under the third aim we will investigate the mechanisms underlying the cytoskeletal changes during fusion by examining novel genes that we have identified. Our work is significant because it expected to reveal the 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.