Angiotensin II initiates tyrosine kinase Pyk2-dependent signalings leading to activation of Rac1-mediated c-Jun NH2-terminal kinase.
Ca(2+)-sensitive tyrosine kinase Pyk2 was shown to be involved in angiotensin (Ang) II-mediated activation of extracellular signal-regulated kinase (ERK) via transactivation of epidermal growth factor receptor (EGF-R). In this study, we tested the involvement of Pyk2 and EGF-R in Ang II-induced activation of JNK and c-Jun in cardiac fibroblasts. Ang II markedly stimulated JNK activities, which were abolished by genistein and intracellular Ca(2+) chelators but partially by protein kinase C depletion. Inhibition of EGF-R did not affect Pyk2 and JNK activation by Ang II. Stable transfection with a dominant negative (DN) mutant for Pyk2 (PKM) completely blocked JNK activation by Ang II. DN mutants of Rac1 (DN-Rac1) and MEK kinase (DN-MEKK1) also abolished it, whereas those of Cdc42, RhoA, and Ha-Ras had no effect. Induction of c-Jun gene transcription by Ang II was abolished in PKM, DN-Rac1, and DN-MEKK1, in which Ang II-induced binding of ATF2/c-Jun heterodimer to the activator protein-1 sequence at -190 played a key role. These results suggest that 1) in cardiac fibroblasts activation of JNK and c-Jun by Ang II is initiated by Pyk2-dependent signalings but not by downstream signals of EGF-R or Ras, 2) Rac1 but not Cdc42 is required for JNK activation by Ang II upstream of MEKK1, and 3) ATF-2/c-Jun binding to the activator protein-1 sequence at -190 plays a key role for induction of c-Jun gene by Ang II.
Murasawa
S
S
Department of Medicine II, Kansai Medical University, Fumizonocho 10-15, Moriguchi, Osaka 570-8507, Japan.
Matsubara
H
H
Mori
Y
Y
Masaki
H
H
Tsutsumi
Y
Y
Shibasaki
Y
Y
Kitabayashi
I
I
Tanaka
Y
Y
Fujiyama
S
S
Koyama
Y
Y
Fujiyama
A
A
Iba
S
S
Iwasaka
T
T
D000804:Angiotensin II / Q000494:pharmacology*; D000818:Animals; D001483:Base Sequence; D020013:Calcium Signaling / Q000187:drug effects*; D002478:Cells, Cultured; D017931:DNA Primers; D004789:Enzyme Activation; D066246:ErbB Receptors / Q000235:genetics; D005347:Fibroblasts / Q000187:drug effects / Q000201:enzymology; D051418:Focal Adhesion Kinase 2; D006352:Heart Ventricles / Q000166:cytology / Q000187:drug effects / Q000201:enzymology; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D011485:Protein Binding; D011493:Protein Kinase C / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D015533:Transcriptional Activation; D020830:rac1 GTP-Binding Protein / Q000378:metabolism*; D019061:src-Family Kinases / Q000235:genetics
D017931:DNA Primers; D016755:Proto-Oncogene Proteins c-jun; D000804:Angiotensin II; D066246:ErbB Receptors; D011505:Protein-Tyrosine Kinases; D051418:Focal Adhesion Kinase 2; C496054:Ptk2b protein, rat; D019061:src-Family Kinases; D011493:Protein Kinase C; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D020830:rac1 GTP-Binding Protein