G(i)-dependent activation of c-Jun N-terminal kinase in human embryonal kidney 293 cells.
Heterotrimeric G proteins stimulate the activities of two stress-activated protein kinases, c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase in mammalian cells. In this study, we examined whether alpha subunits of G(i) family activate JNK using transient expression system in human embryonal kidney 293 cells. Constitutively activated mutants of Galpha(i1), Galpha(i2), and Galpha(i3) increased JNK activity. In contrast, constitutively activated Galpha(o) and Galpha(z) mutants did not stimulate JNK activity. To examine the mechanism of JNK activation by Galpha(i), kinase-deficient mutants of mitogen-activated protein kinase kinase 4 (MKK4) and 7 (MKK7), which are known to be JNK activators, were transfected into the cells. However, Galpha(i)-induced JNK activation was not blocked effectively by kinase-deficient MKK4 and MKK7. In addition, activated Galpha(i) mutant failed to stimulate MKK4 and MKK7 activities. Furthermore, JNK activation by Galpha(i) was inhibited by dominant-negative Rho and Cdc42 and tyrosine kinase inhibitors, but not dominant-negative Rac and phosphatidylinositol 3-kinase inhibitors. These results indicate that Galpha(i) regulates JNK activity dependent on small GTPases Rho and Cdc42 and on tyrosine kinase but not on MKK4 and MKK7.
Yamauchi
J
J
Faculty of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8501, Japan.
Kawano
T
T
Nagao
M
M
Kaziro
Y
Y
Itoh
H
H
D002478:Cells, Cultured; D004789:Enzyme Activation; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000378:metabolism*; D044387:GTP-Binding Protein beta Subunits; D044388:GTP-Binding Protein gamma Subunits; D019204:GTP-Binding Proteins / Q000378:metabolism; D020962:Heterotrimeric GTP-Binding Proteins; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins; D048031:JNK Mitogen-Activated Protein Kinases; D007668:Kidney / Q000166:cytology / Q000196:embryology; D048670:MAP Kinase Kinase 4; D048688:MAP Kinase Kinase 7; D020929:Mitogen-Activated Protein Kinase Kinases; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D008954:Models, Biological; D010455:Peptides; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D011494:Protein Kinases / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D015398:Signal Transduction; D014862:Wasp Venoms / Q000494:pharmacology; D020764:cdc42 GTP-Binding Protein / Q000378:metabolism; D020741:rho GTP-Binding Proteins / Q000378:metabolism; D019061:src-Family Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism
D019206:GTP-Binding Protein alpha Subunits, Gi-Go; D044387:GTP-Binding Protein beta Subunits; D044388:GTP-Binding Protein gamma Subunits; D019204:GTP-Binding Proteins; D020962:Heterotrimeric GTP-Binding Proteins; D036341:Intercellular Signaling Peptides and Proteins; D048031:JNK Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D048688:MAP Kinase Kinase 7; D020929:Mitogen-Activated Protein Kinase Kinases; D020928:Mitogen-Activated Protein Kinases; D010455:Peptides; D019869:Phosphatidylinositol 3-Kinases; D011494:Protein Kinases; D017346:Protein Serine-Threonine Kinases; D011505:Protein-Tyrosine Kinases; D014862:Wasp Venoms; D020764:cdc42 GTP-Binding Protein; D020741:rho GTP-Binding Proteins; D019061:src-Family Kinases; C118981:G-protein Beta gamma; C037500:mastoparan; C482559:MAP2K4 protein, human; C482569:MAP2K7 protein, human