TURNING OF RETINAL GROWTH CONES IN A NETRIN-1 GRADIENT MEDIATED BY THE NETRIN RECEPTOR DCC

Netrin-1 promotes outgrowth of axons in vitro through the receptor Del eted in Colorectal Cancer (DCC) and elicits turning of axons within em bryonic explants when presented as a point source. It is not known whe ther netrin-1 alone can elicit turning nor whether DCC mediates the tu rning response. We show that Xenopus retinal ganglion cell growth cone s orient rapidly toward a pipette ejecting netrin-1, an effect blocked by antibodies to DCC. In vitro, netrin-1 induces a complex growth con e morphology reminiscent of that at the optic nerve head, a site of ne trin-1 expression in vivo. These results demonstrate that netrin-1 can function alone to induce turning, implicate DCC in this response, and support the idea that netrin-1 contributes to steering axons out of t he retina.