Analysis of Myotome Boundary Morphogenesis During Zebrafish Development

描述（由申请人提供）：早期发育阶段的肌肉形成对正常肌肉功能至关重要。许多疾病破坏肌肉的生理机能。然而，这些疾病病理背后的细胞和分子网络尚不清楚。因为肌肉的每一步分化都转化为功能生理学的逐步完善，研究肌肉发育可以显著地告知我们对肌肉功能和生理学的理解。我们实验室的长期目标是利用斑马鱼模型阐明导致精心编排的细胞行为产生功能性肌肉的信号网络。斑马鱼是一个很好的模型系统，它整合了遗传、分子和细胞生物学机制，这些机制是肌肉发育的基础。斑马鱼骨骼肌由节段性重复肌组组成。这些肌瘤包含附着于肌瘤边界的长肌纤维。斑马鱼肌组边界在分子和功能上与哺乳动物肌腱相似：它主要由胶原蛋白组成，并将肌肉产生的力量传递给骨骼系统。在发育过程中肌纤维和肌组边界的形成对正常的肌肉骨骼功能至关重要。初步数据阐明了肌瘤边界的空间复杂性以及肌纤维形成的形态发生步骤。我们假设细胞外基底膜蛋白，层粘连蛋白，在肌肉发育的多个步骤中是至关重要的。本研究的目的是：1)验证层粘连蛋白对于肌前细胞向长肌纤维的初始延伸是必需的这一假设，并确定层粘连蛋白需要的机制；2)验证层粘连蛋白对于肌组边界维持是至关重要的这一假设，并确定这一需求的潜在机制；3)验证层粘连蛋白和Hedgehog信号在边界形态发生过程中相互作用的假设。我们利用斑马鱼的胚胎学和遗传学来阐明肌肉发育的新方面，可能为肌肉/肌腱疾病和创伤性/过度使用损伤的治疗提供信息和有益的治疗。

DESCRIPTION (provided by applicant): Muscle formation during early development is critical for normal muscle function. Many diseases disrupt muscle physiology. However, the cell and molecular networks that underlie the pathology of these diseases are not known. Because each step of muscle specification and differentiation translates to the progressive refinement of functional physiology, studying muscle development can significantly inform our understanding of muscle function and physiology. The long-term goal of our lab is to elucidate the signaling networks that lead to the carefully choreographed cell behaviors that generate functional muscle using the zebrafish model. The zebrafish is an excellent model system with which to integrate the genetic, molecular, and cell biological mechanisms that underlie muscle development. Zebrafish skeletal muscle is comprised of segmentally reiterated myotomes. These myotomes contain long muscle fibers that attach to myotome boundaries. The zebrafish myotome boundary is molecularly and functionally homologous to the mammalian tendon: it is comprised mainly of collagen and transmits muscle generated force to the skeletal system. Both muscle fiber and myotome boundary formation during development are critical for normal musculoskeletal function. Preliminary data elucidate the spatial complexity of the myotome boundary as well as the morphogenetic steps that underlie muscle fiber formation. We hypothesize that an extracellular basement membrane protein, laminin, is critical for multiple steps in muscle development. The aims of this proposal are to: 1) test the hypothesis that laminin is necessary for the initial elongation of muscle precursor cells into long muscle fibers and determine the mechanism by which laminin is required, 2) test the hypothesis that laminin is crucial for myotome boundary maintenance and determine the underlying mechanism for this requirement, and 3) test the hypothesis that laminin and Hedgehog signaling interact during boundary morphogenesis. Our use of the embryology and genetics of the zebrafish to elucidate novel aspects of muscle development may inform and benefit treatments of both muscle/tendon diseases and traumatic/overuse injuries.