A metalloprotease-disintegrin participating in myoblast fusion

Abstract

SKELETAL muscle development involves the formation of multi-nucleated myotubes. This is thought to proceed by the induction of differentiation (acquisition of fusion competence) of myoblast cells, their aggregation, and union of their plasma membranes^1á¤-3. Various membrane proteins including N-^4,5 and M-cadherins⁶, N-^5,7-9 and V-CAMs¹⁰ and integrins^10,11 participate in myotube formation, but the molecular mechanisms of muscle cell fusion are poorly understood. Here we report the identification of three new, myoblast-expressed gene products, meltrin-αβ and γ, with homology to both viper haemorrhagic factors^12,13 and fertilin (PH-30)^14,15, a membrane protein involved in eggá¤-sperm fusion. Meltrin-α, a member of the metalloproteinase/disintegrin protein family, appears to be required for myotube formation. Involvement of a fertilin-related protein in myogenesis suggests that there are common mechanisms in gamete and myoblast fusion.