Gs and Gq signalings regulate hPEM-2-induced cell responses in Neuro-2a cells

Abstract

Rho family GTPase-specific guanine nucleotide exchange factors of the Dbl family regulate a variety of cellular events including cytoskeletal arrangement, signal transduction, and gene expression through activation of Rho family GTPases. In this study, we show that hPEM-2 is a downstream effector of Gs and Gq signaling in Neuro-2a neuroblastoma cells. Co-expression with hPEM-2 and GTPase-deficient (constitutively active) mutants of Gαs (GαsQ213L) or Gαq (GαqQ209L), but not other GTPase-deficient mutants of Gα subunit and Gβγ subunits, activated serum response element (SRE)-dependent gene transcription, which is known to be induced by Rho family activation. Although a dominant negative mutant of Rac1 strongly blocks GαsQ213L or GαqQ209L/hPEM-2 activated SRE-dependent gene transcription, those of Cdc42 or RhoA are marginally affected. A PKA inhibitor, H-89, attenuated Gαs/hPEM-2-activated SRE-dependent gene transcription. And a dominant negative mutant of c-Src and an Src inhibitor attenuated GαqQ209L/hPEM-2-activated SRE-dependent gene transcription. Experiments using hPEM-2 deletion mutants indicate that some regions of hPEM-2 play an important role in enhancing SRE activation by Gs and Gq signalings. These results reveal that Gs and Gq signalings regulate hPEM-2 functions through PKA and c-Src in Neuro-2a neuroblastoma cells, respectively.