Analysis of Myotome Boundary Morphogenesis During Zebrafish Development

描述(由申请人提供)：早期发育中的肌肉形成对正常的肌肉功能至关重要。许多疾病扰乱了肌肉的生理。然而，作为这些疾病病理基础的细胞和分子网络尚不清楚。因为肌肉指定和分化的每一步都转化为功能生理学的逐步完善，所以研究肌肉的发育可以极大地帮助我们理解肌肉的功能和生理学。我们实验室的长期目标是阐明导致使用斑马鱼模型产生功能肌肉的精心设计的细胞行为的信号网络。斑马鱼是一个很好的模型系统，它整合了肌肉发育的遗传、分子和细胞生物学机制。斑马鱼骨骼肌由节段性重复的肌节组成。这些肌节含有附着在肌节边界上的长肌肉纤维。斑马鱼肌节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，将肌肉产生的力传递到骨骼系统。发育过程中肌纤维和肌节边界的形成对正常的肌肉骨骼功能至关重要。初步数据阐明了肌节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关键的。这一建议的目的是：1)验证层粘连蛋白是肌肉前体细胞最初伸长成长肌肉纤维所必需的假说，并确定需要层粘连蛋白的机制；2)验证层粘连蛋白对肌小节边界维持至关重要的假说，并确定这一要求的潜在机制；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说。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，可能有助于肌肉/肌腱疾病和创伤/过度使用损伤的治疗。

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.