cGMP-dependent protein kinase inhibits serum-response element-dependent transcription by inhibiting rho activation and functions.
RhoA, in its active GTP-bound form, stimulates transcription through activation of the serum-response factor (SRF). We found that cGMP inhibited serum-induced Rho.GTP loading and transcriptional activation of SRF-dependent reporter genes in smooth muscle and glial cells in a cGMP-dependent protein kinase (G-kinase)-dependent fashion. Serum stimulation of the SRF target gene vinculin was also blocked by cGMP/G-kinase. G-kinase activation inhibited SRF-dependent transcription induced by upstream RhoA activators including Galpha(13) and p115RhoGEF, with Galpha(13)-induced Rho.GTP loading inhibited by G-kinase. G-kinase had no effect on the high activation levels of RhoA(63L) or the double mutant RhoA(63L,188A) but inhibited transcriptional activation by these two RhoA mutants to a similar extent, suggesting an effect downstream of RhoA and independent of RhoA Ser(188) phosphorylation. Constitutively active forms of the Rho effectors Rho kinase (ROK), PKN, and PRK-2 induced SRF-dependent transcription in a cell type-specific fashion with ROK being the most efficient; G-kinase inhibited transcription induced by all three effectors without affecting ROK catalytic activity. G-kinase had no effect on RhoA(63L)-induced morphological changes in glial cells, suggesting distinct transcriptional and cytoskeletal effectors of RhoA. We conclude that G-kinase inhibits SRF-dependent transcription by interfering with RhoA signaling; G-kinase acts both upstream of RhoA, inhibiting serum- or Galpha(13)-induced Rho activation, and downstream of RhoA, inhibiting steps distal to the Rho targets ROK, PKN, and PRK-2.
Gudi
Tanima
T
Department of Medicine, University of California, San Diego, La Jolla, California 92093-0652, USA.
Chen
Jeffrey C
JC
Casteel
Darren E
DE
Seasholtz
Tammy M
TM
Boss
Gerry R
GR
Pilz
Renate B
RB
D000818:Animals; D001483:Base Sequence; D002417:Cattle; D001517:Coleoptera; D006152:Cyclic GMP / Q000494:pharmacology; D062965:Cyclic GMP-Dependent Protein Kinase Type I; D017869:Cyclic GMP-Dependent Protein Kinases / Q000235:genetics / Q000378:metabolism*; D017931:DNA Primers; D018076:DNA, Complementary; D004789:Enzyme Activation / Q000187:drug effects; D005786:Gene Expression Regulation; D017930:Genes, Reporter; D005822:Genetic Vectors; D006321:Heart / Q000502:physiology; D006801:Humans; D008156:Luciferases / Q000235:genetics; D011651:Pulmonary Artery / Q000502:physiology; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D027602:Serum Response Element / Q000502:physiology*; D014158:Transcription, Genetic / Q000502:physiology; D016596:Vinculin / Q000235:genetics; D020742:rhoA GTP-Binding Protein / Q000037:antagonists & inhibitors* / Q000502:physiology
D017931:DNA Primers; D018076:DNA, Complementary; D011993:Recombinant Fusion Proteins; D016596:Vinculin; D008156:Luciferases; D062965:Cyclic GMP-Dependent Protein Kinase Type I; D017869:Cyclic GMP-Dependent Protein Kinases; C569718:PRKG1 protein, human; D020742:rhoA GTP-Binding Protein; D006152:Cyclic GMP