Cooperative transformation of NIH3T3 cells by G alpha12 and Rac1.
The heterotrimeric G-protein, G alpha12, together with the closely-related G alpha13, are members of the G12 class of alpha-subunits important in mediating the signaling from seven transmembrane domain-spanning receptors. Recent evidence implicating both G alpha12 and G alpha13 in the activation of signaling pathways involving members of the RHO gene family led us to examine the role of Rac1, RhoA and Cdc42Hs in the transforming properties of G alpha12. Asparagine 17 (Asn 17) dominant inhibitory mutants of Rac1, and to a lesser extent RhoA, block focus forming ability of the GTPase-deficient mutant of G alpha12 (G alpha12 Leu 229) in NIH3T3 cells. In turn, wild-type G alpha12 cooperates well with Rac1 Val 12 but not with RhoA Leu 63 mutant in transforming NIH3T3 cells. Interestingly, the morphology of foci induced by G alpha12 and RhoA mutants are strikingly similar and is distinct from those displayed by Rac1 Val 12 mutant. The fact that G alpha12's ability to induce mitogenesis in NIH3T3 cells is not significantly perturbed by C3 ribosyltransferase suggested that RhoA does not play a major role in G alpha12-induced mitogenic events. Activated mutant of Rac1 has previously been demonstrated to stimulate the activity of the stress-induced c-Jun N-terminal kinase/stress-activated protein kinases (JNK/SAPKs). Transient co-transfection of Rac1 Val 12 mutant with the wild-type G alpha12 in COS7 cells leads to the further activation of an exogenously expressed hemagglutinin(HA)-tagged JNK. Furthermore, the cooperation between G alpha12 and Rac1 in cellular transformation is correlated with their ability to stimulate transcription from c-fos serum response element (SRE).
Tolkacheva
T
T
The Derald H. Ruttenberg Cancer Center, The Mount Sinai Medical School, New York, NY 10029, USA.
Feuer
B
B
Lorenzi
M V
MV
Saez
R
R
Chan
A M
AM
D016475:3T3 Cells; D000818:Animals; D001216:Asparagine / Q000235:genetics; D019556:COS Cells; D018797:Cell Cycle Proteins / Q000235:genetics / Q000502:physiology; D051960:GTP-Binding Protein alpha Subunit, Gi2; D019206:GTP-Binding Protein alpha Subunits, Gi-Go; D019204:GTP-Binding Proteins / Q000235:genetics* / Q000378:metabolism* / Q000502:physiology*; D006388:Hemagglutinins / Q000378:metabolism; D048031:JNK Mitogen-Activated Protein Kinases; D007930:Leucine / Q000235:genetics; D048670:MAP Kinase Kinase 4; D051379:Mice; D020929:Mitogen-Activated Protein Kinase Kinases; D016296:Mutagenesis; D010957:Plasmids; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D011494:Protein Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000235:genetics* / Q000378:metabolism*; D016760:Proto-Oncogene Proteins c-fos / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D014170:Transformation, Genetic; D014633:Valine / Q000235:genetics; D020764:cdc42 GTP-Binding Protein; D020744:rac GTP-Binding Proteins; D020742:rhoA GTP-Binding Protein
D018797:Cell Cycle Proteins; D006388:Hemagglutinins; D011518:Proto-Oncogene Proteins; D016760:Proto-Oncogene Proteins c-fos; D001216:Asparagine; D011065:Poly(ADP-ribose) Polymerases; D011494:Protein Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D020929:Mitogen-Activated Protein Kinase Kinases; D019204:GTP-Binding Proteins; D051960:GTP-Binding Protein alpha Subunit, Gi2; D019206:GTP-Binding Protein alpha Subunits, Gi-Go; C498016:Gnai2 protein, mouse; D020764:cdc42 GTP-Binding Protein; D020744:rac GTP-Binding Proteins; D020742:rhoA GTP-Binding Protein; D007930:Leucine; D014633:Valine