cGMP-dependent protein kinase phosphorylates and inactivates RhoA.
Small GTPase Rho and cGMP/cGMP-dependent protein kinase (cGK) pathways exert opposing effects in specific systems such as vascular contraction and growth. However, the direct interaction between these pathways has remained elusive. We demonstrate that cGK phosphorylates RhoA in vitro at Ser188, the same residue phosphorylated by cAMP-dependent protein kinase. In HeLa cells transfected with constitutively active cGK (C-cGK), stress fiber formation induced by lysophosphatidic acid or V14RhoA was blocked. By contrast, C-cGK failed to inhibit stress fiber formation in cells transfected with mutant RhoA with substitution of Ser188 to Ala. C-cGK did not affect actin reorganization induced by Rac1 or Rho-associated kinase, one of the effectors for RhoA. Furthermore, C-cGK expression inhibited the membrane translocation of RhoA. Collectively, our findings suggest that cGK phosphorylates RhoA at Ser188 and inactivates RhoA signaling. The physiological relevance of the direct interaction between RhoA and cGK awaits further investigation.
Sawada
N
N
Department of Medicine and Clinical Science, Kyoto University Graduate School of Medicine, 54 Shogoin Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan.
Itoh
H
H
Yamashita
J
J
Doi
K
K
Inoue
M
M
Masatsugu
K
K
Fukunaga
Y
Y
Sakaguchi
S
S
Sone
M
M
Yamahara
K
K
Yurugi
T
T
Nakao
K
K
D000199:Actins / Q000378:metabolism; D001483:Base Sequence; D001693:Biological Transport, Active; D002462:Cell Membrane / Q000378:metabolism; D017869:Cyclic GMP-Dependent Protein Kinases / Q000235:genetics / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism; D017931:DNA Primers / Q000235:genetics; D006367:HeLa Cells; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008246:Lysophospholipids / Q000494:pharmacology; D009154:Mutation; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D012694:Serine / Q000737:chemistry; D014162:Transfection; D020830:rac1 GTP-Binding Protein / Q000378:metabolism; D054460:rho-Associated Kinases; D020742:rhoA GTP-Binding Protein / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
D000199:Actins; D017931:DNA Primers; D047908:Intracellular Signaling Peptides and Proteins; D008246:Lysophospholipids; D012694:Serine; D017346:Protein Serine-Threonine Kinases; D054460:rho-Associated Kinases; D017869:Cyclic GMP-Dependent Protein Kinases; D020830:rac1 GTP-Binding Protein; D020742:rhoA GTP-Binding Protein