DEVELOPMENTAL EXPRESSION OF G-ALPHA(O) AND G-ALPHA(S) ISOFORMS IN PC12 CELLS - RELATIONSHIP TO NEURITE OUTGROWTH

Recent evidence suggests neuronal differentiation is associated with d evelopmentally regulated changes in the expression of certain G-protei n subtypes but the relationship of such changes to neuronal differenti ation and/or neurite outgrowth is poorly understood. In this study, th e appearance of the G-protein alpha(o), and alpha(s) subunit isoforms was characterized in NGF-induced differentiating pheochromocytoma (PC) 12 cells and correlated with neurite outgrowth, which was assessed wit h direct morphometric measures at 24-h intervals for a 5-day period an d at 24, 48 and 72 h following NGF removal. Significant increases were observed in alpha(o1) immunoreactive levels and the ratio of alpha(o1 )/alpha(o2) immunoreactivities during NGF exposure but not in the leve ls of either the long or short isoform of alpha(s). The former changes also correlated significantly with neurite length during NGF treatmen t. Furthermore, no significant changes were observed in the levels of alpha(o) or alpha(s) isoforms following NGF removal. These findings su ggest that alpha(o) isoforms are involved in neuritic extension in PC1 2 cells.