Dystrophin and utrophin: genetic analyses of their role in skeletal muscle.

Since the identification of dystrophin as the causitive factor in Duchenne muscular dystrophy, there has been substantial progress in understanding the functions and interactions of this protein. Dystrophin has been shown to interact with a group of peripheral- and trans-membrane proteins known as the dystrophin-associated protein complex (DAPC) and mutations in some of the members of this complex have been shown to account for other forms of muscular dystrophy. This review summarizes the experiments using transgenic and knockout mouse models that have defined the roles of dystrophin, and the dystrophin-related protein utrophin at the skeletal muscle membrane and at the neuromuscular junction. These studies are presented in the context of other known interactions at the muscle membrane. Studies of the dystrophin-deficient mdx mouse have lead to a greater understanding of the human disease. Knockouts and transgenics of utrophin have shown this protein to be sufficient to functionally compensate for dystrophin. Dystrophin transgenic mice combined with the mdx mouse have been used to study the function of specific domains of the dystrophin protein. Together these animal models have led to a delineation of protein functions and localization patterns that will be useful for the generation of potential therapies for DMD.