ADAM 12 DISINTEGRIN DOMAIN AND MYOBLAST FUSION

成肌细胞融合对骨骼肌的发育和修复是必不可少的 在受伤或退化之后。尽管有许多因素 与成肌细胞融合有关，其确切机制 这一过程仍不得而知。更好地理解分子事件 因此，在一个人可以计划之前，需要与聚变相关联 旨在加强肌肉修复或优化基因治疗的策略 利用成肌细胞作为靶向基因转移到疾病中的载体 肌肉。 在拟议的研究中，我们将调查亚当12的角色，成员 属于亚当蛋白家族(包含去整合素和 在成肌细胞融合中)。我们假设 ADAM 12去整合素结构域与成肌细胞整合素受体结合 膜和ADAM-整合素相互作用提供了一种机制 成肌细胞的自我识别导致融合。我们的长期目标是 将这些研究扩展到亚当12的其他领域，并获得一个 成肌细胞中ADAM-12功能的研究进展 沟通与融合。 首先，我们将调查亚当12的同源区域是否 可溶性去整合素构成一个自主的蛋白质结构域，并具有 具有执行独特生化功能的潜力。那么，我们会 从成肌细胞质膜中鉴定能与之相互作用的受体 去整合素结构域。使用定点突变，我们将 确定哪些残基和哪些结构签名 去整合素结构域是相互作用的关键。如果新的 已鉴定的受体属于整合素家族，我们将研究 如果去整合素的结合触发任何已知的整合素信号 小路。最后，我们将评估去整合素的重要性- 通过研究封闭效应在成肌细胞融合中介导的黏附 或者消除亚当去整合素结构域之间的相互作用 12及其受体。

Myoblast fusion is essential for skeletal muscle development and repair following injury or degeneration. Although a number of factors have been implicated in myoblast fusion, the precise mechanism of this process remains unknown. A better understanding of the molecular events associated with fusion is, therefore, required before one can plan strategies aimed to enhance muscle repair or to optimize gene therapies employing myoblasts as vehicles for targeted gene delivery into diseased muscle. In the proposed studies, we will investigate a role of ADAM 12, a member of the ADAM family of proteins (containing A Disintegrin And Metalloprotease domain) in myoblast fusion. We hypothesize that the disintegrin domain of ADAM 12 binds to an integrin receptor in myoblast membrane and that ADAM-integrin interactions provide a mechanism of myoblast self-recognition that leads to fusion. Our long-term goal is to extend these studies to other domains of ADAM 12 and to obtain a comprehensive understanding of ADAM 12 function in myoblast communication and fusion. First, we will investigate if the region of ADAM 12 that is homologous to soluble disintegrins constitutes an autonomous protein domain and has a potential to execute a distinct biochemical function. Then, we will identify a receptor from myoblast plasma membrane that can interact with the disintegrin domain. Using site-directed mutagenesis, we will determine what residues and what structural signatures of the disintegrin domain are critical for the interactions. If the newly identified receptor belongs to the integrin family, we will investigate if binding of disintegrin triggers any of the known integrin signaling pathways. Finally, we will evaluate the importance of the disintegrin- mediated adhesion in myoblast fusion by studying the effects of blocking or eliminating the interactions between the disintegrin domain of ADAM 12 and its receptor.