THE ZINC-FINGER TRANSCRIPTION FACTOR ZIF268 EGR-1 IS ESSENTIAL FOR SCHWANN-CELL EXPRESSION OF THE P75 NGF RECEPTOR/

Nerve injury alters the function of Schwann cells from quiescent, myel in forming cells to proliferating cells that facilitate nerve repair. The transcription factor, Zif268, may be involved in transmitting inju ry-related signals since its expression is rapidly induced by nerve tr ansection in vivo and without intervening protein synthesis by injury- related signals in vitro. Expression of the low-affinity p75 nerve gro wth factor receptor (NGFR(p75)) by Schwann cells after nerve injury cl osely correlated with the zif268 expression profile, and Zif268 transa ctivated the NGFR(p75) promoter in transient transfection assays. Conv ersely, the NGFR(p75) gene was not expressed when Zif268 protein was d epleted by stable transfection of antisense cDNA. Moreover, nuclear pr oteins corresponding to Zif268 bound to the NGFR(p75) promoter by Sout hwestern blotting, indicating that a direct interaction of Zif268 with the NGFR gene is required for its expression in Schwann cells.