Open AccessProtein kinase A antagonizes platelet-derived growth factor-induced signaling by mitogen-activated protein kinase in human arterial smooth muscle cells.
Author(s) -
Lee M. Graves,
Karin E. Bornfeldt,
Elaine W. Raines,
Brian C. Potts,
Susan G. Macdonald,
Russell Ross,
Edwin G. Krebs
Publication year - 1993
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.90.21.10300
Subject(s) - forskolin , protein kinase a , platelet derived growth factor receptor , mapk/erk pathway , microbiology and biotechnology , mitogen activated protein kinase kinase , autophosphorylation , phosphodiesterase 3 , biology , map kinase kinase kinase , platelet derived growth factor , signal transduction , endocrinology , medicine , growth factor , chemistry , kinase , biochemistry , receptor , stimulation
Stimulation of aortic smooth muscle cells with platelet-derived growth factor BB homodimer (PDGF-BB) leads to the rapid activation of mitogen-activated protein kinase (MAPK) and MAPK kinase (MAPKK). Compounds that increase cAMP and activate protein kinase A (PKA)--prostaglandin E2, isoproterenol, cholera toxin, and forskolin--were found to inhibit the PDGF-BB-induced activation of MAPKK and MAPK. Forskolin, but not the inactive analogue 1,9-dideoxyforskolin, inhibited PDGF-BB-stimulated MAPKK and MAPK activation in a dose-dependent manner. PKA antagonism of MAPK signaling was observed at all doses of PDGF-BB or PDGF-AA. PKA did not inhibit MAPKK and MAPK activity in vitro, and MAPKK and MAPK from extracts of forskolin-treated cells could be activated normally with purified Raf-1 and MAPKK, respectively, suggesting that PKA blocked signaling upstream of MAPKK. Neither PDGF-BB-stimulated tyrosine autophosphorylation of the PDGF receptor beta subunit nor inositol monophosphate accumulation was affected by increased PKA activity, suggesting that PKA inhibits events downstream of the PDGF receptor. This study provides an example of cross talk between two important signaling systems activated by physiological stimuli in smooth muscle cells--namely, the PKA pathway and the growth factor-activated MAPK cascade.