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

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 G(s) and G(q) signaling in Neuro-2a neuroblastoma cells. Co-expression with hPEM-2 and GTPase-deficient (constitutively active) mutants of Gαs (Gα(s)Q213L) or Gα(q) (Gα(q)Q209L), 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 Gα(s)Q213L or Gα(q)Q209L/hPEM-2 activated SRE-dependent gene transcription, those of Cdc42 or RhoA are marginally affected. A PKA inhibitor, H-89, attenuated Gα(s)/hPEM-2-activated SRE-dependent gene transcription. And a dominant negative mutant of c-Src and an Src inhibitor attenuated Gα(q)Q209L/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 G(s) and G(q) signalings. These results reveal that G(s) and G(q) signalings regulate hPEM-2 functions through PKA and c-Src in Neuro-2a neuroblastoma cells, respectively.