Regulation of cGMP-dependent protein kinase expression by Rho and Kruppel-like transcription factor-4.
Type I cGMP-dependent protein kinase (PKG I) plays a major role in vascular homeostasis by mediating smooth muscle relaxation in response to nitric oxide, but little is known about the regulation of PKG I expression in smooth muscle cells. We found opposing effects of RhoA and Rac1 on cellular PKG I expression: (i) cell density-dependent changes in PKG I expression varied directly with Rac1 activity and inversely with RhoA activity; (ii) RhoA activation by calpeptin suppressed PKG I, whereas RhoA down-regulation by small interfering RNA increased PKG I expression; and (iii) PKG I promoter activity was suppressed in cells expressing active RhoA or Rho-kinase but was enhanced in cells expressing active Rac1 or a dominant negative RhoA. Sp1 consensus sequences in the PKG I promoter were required for Rho regulation and bound nuclear proteins in a cell density-dependent manner, including the Krüppel-like factor 4 (KLF4). KLF4 was identified as a major trans-acting factor at two proximal Sp1 sites; active RhoA suppressed KLF4 DNA binding and trans-activation potential on the PKG I promoter. Experiments with actin-binding agents suggested that RhoA could regulate KLF4 via its ability to induce actin polymerization. Regulation of PKG I expression by RhoA may explain decreased PKG I levels in vascular smooth muscle cells found in some models of hypertension and vascular injury.
Zeng
Ying
Y
Department of Medicine and Cancer Center, University of California at San Diego, La Jolla, California 92093.
Zhuang
Shunhui
S
Department of Medicine and Cancer Center, University of California at San Diego, La Jolla, California 92093.
Gloddek
Jutta
J
Department of Medicine and Cancer Center, University of California at San Diego, La Jolla, California 92093.
Tseng
Chi-Chuan
CC
Section of Gastroenterology, Boston University School of Medicine, Boston, Massachusetts 02118.
Boss
Gerry R
GR
Department of Medicine and Cancer Center, University of California at San Diego, La Jolla, California 92093.
Pilz
Renate B
RB
Department of Medicine and Cancer Center, University of California at San Diego, La Jolla, California 92093. Electronic address: rpilz@ucsd.edu.
D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism; D017869:Cyclic GMP-Dependent Protein Kinases / Q000096:biosynthesis*; D004151:Dipeptides / Q000737:chemistry; D005786:Gene Expression Regulation; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D000090062:Kruppel-Like Factor 4; D051741:Kruppel-Like Transcription Factors / Q000378:metabolism*; D009130:Muscle, Smooth / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism; D051381:Rats; D016329:Sp1 Transcription Factor / Q000378:metabolism; D020830:rac1 GTP-Binding Protein / Q000378:metabolism; D020741:rho GTP-Binding Proteins / Q000378:metabolism*
D004151:Dipeptides; C000715467:KLF4 protein, human; C000715469:Klf4 protein, rat; D000090062:Kruppel-Like Factor 4; D051741:Kruppel-Like Transcription Factors; D016329:Sp1 Transcription Factor; C071482:calpeptin; D009569:Nitric Oxide; D017869:Cyclic GMP-Dependent Protein Kinases; D020830:rac1 GTP-Binding Protein; D020741:rho GTP-Binding Proteins