Phosphoinositide metabolism and its role in skeletal myogenesis

骨骼肌的主要功能是产生运动所需的力量。肌肉有几个独特的结构来帮助它完成这个功能，包括神经肌肉连接处、三联肌和肌节。一般来说，我们对肌肉的发育（称为肌生成）了解甚多。然而，指导和控制肌肉独特的力量产生结构的产生和维持的关键分子却知之甚少。我们研究的首要目标是定义控制这些结构的生物发生的分子事件。我们小组和其他人最近的工作已经确定了磷酸肌苷（PIPs）和调节它们的酶是骨骼肌发育的潜在关键因素。pip是一种脂质，具有共同的主干，但根据磷酸基团的含量和位置而不同。有7个独立的pip，每个都有独特的定位、调节和生物功能。虽然有广泛的知识体系与pip在单个细胞中的功能有关，但它们在骨骼肌中的作用尚未得到系统的研究。因此，本提案的具体目的是了解pip与肌肉发育之间的关系，目的是确定pip在独特细胞亚结构形成中的作用，使肌肉能够执行其特殊功能。我们将通过以下方式实现这一目标：(1)在肌肉形成过程中建立个体pip在关键肌肉亚结构的时空定位，(2)确定肌肉亚结构形成和维持对pip的总体需求，以及(3)了解个体pip在肌肉形成，特别是神经肌肉连接和三联体形成中的具体作用。为了做到这一点，我们将利用斑马鱼模型系统，并利用我们开发的许多工具来研究它的肌肉结构和功能。这项研究的成功完成将极大地促进对肌肉发育的理解。特别是，它将首次定义肌形成中pip的需求，特别是定义骨骼肌的独特亚细胞结构的形成。我们的发现将对肌肉生物学社区具有重要的意义，也将对pip和器官生物发生的研究产生重大影响。

Skeletal muscle’s main function is to generate force to enable movement. Muscle has several unique structures that help it to perform this function, including the neuromuscular junction, the triad, and the sarcomere. Much is known about muscle development (called myogenesis) in very general terms. However, the key molecules that guide and control the creation and maintenance of muscle’s unique force generating structures are poorly understood. The overarching goal of our research is to define the molecular events that govern the biogenesis of these structures. Recent work from our group and others has identified phosphoinositides (PIPs) and the enzymes that regulate them as potentially key players for skeletal muscle development. PIPs are lipids that share a common backbone but differ based on phosphate group content and position. There are seven individual PIPs, each with unique localization, regulation, and biologic function. While there is an extensive body of knowledge related to function of PIPs in individual cells, their role(s) in skeletal muscle has yet to be systematically examined. The specific purpose of this proposal, therefore, is to understand the relationship between PIPs and muscle development with the goal of defining the role of PIPs in the formation of the unique cellular substructures that enable muscle to perform its specialized function(s). We will accomplish this goal by (1) establishing the spatial and temporal localization of individual PIPs at the key muscle substructures during myogenesis, (2) determining the overall requirement for PIPs for muscle substructure formation and maintenance, and (3) understanding the specific role of individual PIPs in myogenesis and particularly for neuromuscular junction and triad formation. To do this, we will utilize the zebrafish model system, and take advantage of the many tools we have developed for studying muscle structure and function in it. Successful completion of the proposed research will significantly advance the understanding of muscle development. In particular, it will define for the first time the requirement(s) for PIPs in myogenesis and specifically for the formation of the unique subcellular structures that define skeletal muscle. Our findings will be of great relevance and importance to the muscle biology community, and will also significantly impact the study of PIPs and organ biogenesis.