UNC-40, A C-ELEGANS HOMOLOG OF DCC (DELETED IN COLORECTAL-CANCER), ISREQUIRED IN MOTILE CELLS RESPONDING TO UNC-6 NETRIN CUES

UNC-6 netrin, a laminin-related protein secreted from neuroglia and ne urons along the ventral midline, orients migrating cells and pioneerin g growth cones on the nematode epidermis. UNC-5, a cell surface protei n expressed on motile cells and pioneer axons, orients movements away from UNC-6 sources. UNC-40, a homolog of the cell surface proteins DCC (Deleted in Colorectal Cancer) and neogenin, is also expressed on mot ile cells and pioneer neurons. UNC-40 acts cell autonomously to orient movement toward UNC-6 sources. For cells coexpressing UNC-5, it helps orient movement away from UNC-6 sources. Finally, UNC-40 helps determ ine the dorsoventral position of cells undergoing purely longitudinal migrations. Together with the recent report that DCC is a netrin recep tor in vertebrates, our results suggest that UNC-40 is a component of UNC-6 receptors on motile cells.