A mutant substituting valine for glycine at position 49 of Gsα induces neuronal differentiation of PC12 cells without activation of adenylate cyclase

Abstract A GTPase-deficient mutant of the α-subunit of Gs, the guanine nucleotide-binding regulatory protein that stimulates adenylate cyclase, substituting valine for glycine 49 (G49V) was transiently expressed in COS7 cells. The basal level of cAMP as well as an agonist-dependent accumulation of cAMP was two-fold higher in transfectants of Gsα(G49V) than in those of the normal counterpart. A stable transformant of PC12 cells expressing Gsα (G49V) under the control of a metallothionein promoter was then established. Two independent clones showed neurite outgrowth when the mutated Gsα was expressed by adding Cd 2+ to culture medium. However, the level of basal cAMP of the transformant of PC12 cells with Gsα(G49V) was lower than that of the parental cells. The response to an agonist of the adenosine A 2 -receptor was suppressed in transformants. Although a cAMP-responsive element (CRE) was slightly activated by transfection and transient expression of Gsα in PC12 cells, no activation but a suppression of CRE was observed with PC12 cells transiently expressing Gsα(G49V). These results suggest that the mutant Gsα(G49V) couples adenylate cyclase in a different way in PC12 cells and may transduce differentiation signals through a cAMP-independent pathway.