NGF-MEDIATED SURVIVAL DEPENDS ON P21RAS IN CHICK SYMPATHETIC NEURONS FROM THE SUPERIOR CERVICAL BUT NOT FROM LUMBOSACRAL GANGLIA

In rat embryonic sympathetic neurons from the superior cervical gangli a (SCG) NGF-mediated survival depends on the activation of the trkA re ceptor tyrosine kinase and on the activity of the intracellular plasma membrane-anchored small G-protein p21ras. In contrast, chick sympathet ic neurons derived from the more caudally located lumbosacral chain ga nglia (LSCG) do not respond to activated p21ras (G12V-Ha-ras mutant). In these neurons endogenous p21ras and its downstream effector MAP kin ase are activated but are not essential for NGF-dependent survival. He re we show that also in chick sympathetic neurons of the SCG permanent ly activated p21ras protein does promote neuron survival. Consistently , their NGF-mediated survival is sensitive to Fab fragments blocking e ndogenous p21ras activity. These results suggest that sympathetic neur ons derived from sympathoenteric (SCG) and sympathoadrenal (LSCG) line ages differ in their requirement for p21ras in the NGF-mediated surviv al pathways. (C) 1997 Academic Press.