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 developmentally regulated changes in the expression of certain G-protein subtypes but the relationship of such changes to neuronal differentiation and/or neurite outgrowth is poorly understood. In this study, the 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 with direct morphometric measures at 24-h intervals for a 5-day period and 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 levels of either the long or short isoform of alpha(s). The former changes also correlated significantly with neurite length during NGF treatment. Furthermore, no significant changes were observed in the levels of alpha(o) or alpha(s) isoforms following NGF removal. These findings suggest that alpha(o) isoforms are involved in neuritic extension in PC12 cells.