DERAILED IS REQUIRED FOR MUSCLE ATTACHMENT SITE SELECTION IN DROSOPHILA

During development, muscles must form and attach at highly stereotyped positions to allow for coordinated movements. In Drosophila, muscles grow towards and attach to specifically positioned cells within the ep idermis. At the molecular level, very little is known about how muscle s recognize these attachment sites, The derailed gene encodes a recept or tyrosine kinase family member that is essential for the pathfinding ability of expressing neurons, Here we show that the Drl RTK is also expressed by a small subset of developing embryonic muscles and neighb oring epidermal cells during muscle attachment site selection. In drl mutants, these muscles often fail to attach at appropriate locations a lthough their epidermal attachment cells appear unaffected. These resu lts show that, similar to its role in neuronal pathway recognition, th e Drl RTK participates in a mechanism required for muscle attachment s ite selection. The data suggest that both neurons and muscles use comm on mechanisms to recognize their paths or targets, and that Drl plays an analogous role in both developing systems.