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- Title
Sequential activation of MAP kinase cascade by angiotensin II in opossum kidney cells.
- Authors
Terada, Yoshio; Tomita, Kimio; Homma, Miwako K.; Nonoguchi, Hiroshi; Yang, Tianxin; Yamada, Takehisa; Yuasa, Yasuhiro; Krebs, Edwin G.; Marumo, Fumiaki
- Abstract
Angiotensin-II (Ang II) is a potent regulator of proximal tubule functions, including transport, metabolism, and cell proliferation. The opossum kidney (OK) cell line is a useful model of renal proximal tubule. Mitogen-activated protein (MAP) kinases are rapidly phosphorylated and activated in response to various agonists. We investigated Ang II effects on serine/threonine kinase cascades in OK cells. The major findings of the present study are that Ang II stimulated MAP kinase kinase (MAPKK), MAP kinase (MAPK), and S6 kinase activities, and that it increased phosphorylation of Raf-1 kinase and p42 MAP kinase in OK cells. These stimulations of kinases were dose-dependent (from 10-6 to 1.0-11 M). The time course of activation was sequential, the peak stimulation was reached at 5 to 10 minutes for Raf-1 kinase, MAPKK and MAPK, and at 20 minutes for S6 kinase. The activation of MAPK was inhibited by approximately 70% with prolonged 24-hour PMA pretreatment or in the presence of calphostin C or H-7. Tyrosine kinase inhibitors (genistein and herbimycin) did not inhibit Ang II-induced MAPK activity. This activation of MAPK was also inhibited via AT1 receptor antagonist, Dup753 and pertussis toxin. This evidence suggests that the activation of serine/threonine cascades by Ang II is largely dependent on PMA-sensitive PKC, and is not dependent on tyrosine kinase and pertusis toxin.
- Subjects
MITOGEN-activated protein kinases; ANGIOTENSIN II; PEPTIDE hormones; PHOSPHORYLATION; CHEMICAL reactions; PROTEIN-tyrosine kinases
- Publication
Kidney International, 1995, Vol 48, Issue 6, p1801
- ISSN
0085-2538
- Publication type
Article
- DOI
10.1038/ki.1995.478