The Src family tyrosine kinase is involved in Rho-dependent activation of c-Jun N-terminal kinase by Galpha12.
Gt12, a member of alpha subunit of heterotrimeric G protein G12 subfamily, has been shown to stimulate c-Jun N-terminal kinase (JNK) activity through the low molecular weight GTP-binding proteins Ras, Rac, and Cdc42. In this study using the transient expression of a constitutively activated mutant of Galpha12 (Galpha12Q229L) in human embryonic kidney (HEK) 293 cells, we found that Rho and Src family kinase are also involved in the Galpha12-induced activation of JNK. The activation of JNK by Galpha12Q229L was inhibited by dominant-negative RhoA(T19N), and botulinum C3 exoenzyme which specifically inactivates Rho. In addition, the expression of activated RhoA(G14V) elevated JNK activity in HEK 293 cells. The Galpha12Q229L-stimulated activation of JNK was blocked by a specific inhibitor of protein tyrosine kinases (PP2), and C-terminal Src kinase (Csk). Moreover, we observed that Galpha12Q229L stimulated Src family kinase activity and v-Src induced JNK activation. Interestingly, the v-Src-induced activation of JNK was inhibited by dominant-negative RhoA(T19N). In contrast, Csk did not inhibit the JNK activation by activated RhoA(G14V). These results suggest that Rho and Src family kinase are required for the Galpha12-induced JNK activation, and that Src family kinase acts upstream of Rho activation in the JNK pathway.
Nagao
M
M
Faculty of Bioscience and Biotechnology, Tokyo Institute of Technology, Yokohama, Japan.
Kaziro
Y
Y
Itoh
H
H
D016475:3T3 Cells; D019943:Amino Acid Substitution; D000818:Animals; D019556:COS Cells; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D002460:Cell Line; D017931:DNA Primers; D004789:Enzyme Activation; D051960:GTP-Binding Protein alpha Subunit, Gi2; D019206:GTP-Binding Protein alpha Subunits, Gi-Go; D019204:GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases; D051379:Mice; D020928:Mitogen-Activated Protein Kinases; D016297:Mutagenesis, Site-Directed; D016133:Polymerase Chain Reaction; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D014162:Transfection; D020742:rhoA GTP-Binding Protein; D018909:src Homology Domains
D017931:DNA Primers; D011518:Proto-Oncogene Proteins; D011993:Recombinant Fusion Proteins; D011505:Protein-Tyrosine Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D019204:GTP-Binding Proteins; C498015:GNAI2 protein, human; D051960:GTP-Binding Protein alpha Subunit, Gi2; D019206:GTP-Binding Protein alpha Subunits, Gi-Go; C498016:Gnai2 protein, mouse; C498017:Gnai2 protein, rat; D020742:rhoA GTP-Binding Protein