title: Sp1 transcription factor as a molecular target for nitric oxide-- and cyclic nucleotide--mediated suppression of cGMP-dependent protein kinase-Ialpha expression in vascular smooth muscle cells.
abstract: cGMP-dependent protein kinase (PKG) expression is highly variable and decreases in cultured vascular smooth muscle cells (VSMCs), exposure of cells to nitric oxide (NO), or in response to balloon catheter injury in vivo. In this study, the mechanisms of human type I PKG-alpha (PKG-Ialpha) gene expression were examined. Three structurally unrelated NO donors decreased PKG-Ialpha promoter activity after transfection of a promoter/luciferase construct in VSMCs. Promoter deletion analysis demonstrated that (1) a 120-bp promoter containing tandem Sp1 sites was sufficient to drive basal PKG-Ialpha promoter activity, and (2) NO was inhibitory at this site. Cyclic nucleotide analogues also suppressed PKG-Ialpha promoter activity with cAMP being more potent than cGMP. The effects of cyclic nucleotides to suppress PKG-Ialpha promoter activity were attenuated by a specific cAMP-dependent protein kinase (PKA) inhibitor. Single or double mutation of Sp1 binding sites abolished PKG-Ialpha expression. Moreover, Sp1 binding activity on the PKG-Ialpha promoter was detected in A7r5 cells, and this binding was inhibited by NO and cyclic nucleotides. These results indicate that PKG-Ialpha gene expression is driven by an Sp1 transcription mechanism, and that NO and cAMP inhibit Sp1-mediated PKG-Ialpha gene expression through separate mechanisms.
authors.affiliation: Department of Molecular and Cellular Pathology, University of Alabama in Birmingham, 35294-0019, USA.
authors.forename: Hassan
authors.initials: H
authors.lastname: Sellak
authors.forename: Xiangli
authors.initials: X
authors.lastname: Yang
authors.forename: Xu
authors.initials: X
authors.lastname: Cao
authors.forename: Trudy
authors.initials: T
authors.lastname: Cornwell
authors.forename: Gerald A
authors.initials: GA
authors.lastname: Soff
authors.forename: Thomas
authors.initials: T
authors.lastname: Lincoln
mesh_terms: D000818:Animals; D001665:Binding Sites / Q000502:physiology; D002417:Cattle; D002478:Cells, Cultured; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D062965:Cyclic GMP-Dependent Protein Kinase Type I; D017869:Cyclic GMP-Dependent Protein Kinases / Q000235:genetics / Q000378:metabolism*; D015536:Down-Regulation / Q000187:drug effects / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015870:Gene Expression / Q000187:drug effects / Q000502:physiology; D017930:Genes, Reporter; D006162:Guanylate Cyclase; D006801:Humans; D008070:Lipopolysaccharides / Q000494:pharmacology; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D016297:Mutagenesis, Site-Directed; D009569:Nitric Oxide / Q000096:biosynthesis / Q000494:pharmacology*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D009712:Nucleotides, Cyclic / Q000494:pharmacology*; D011401:Promoter Regions, Genetic / Q000187:drug effects / Q000502:physiology; D011485:Protein Binding / Q000187:drug effects / Q000502:physiology; D051381:Rats; D018160:Receptors, Cytoplasmic and Nuclear / Q000037:antagonists & inhibitors; D000071756:Soluble Guanylyl Cyclase; D016329:Sp1 Transcription Factor / Q000037:antagonists & inhibitors / Q000378:metabolism*; D014162:Transfection; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
chemical_list: D004791:Enzyme Inhibitors; D008070:Lipopolysaccharides; D020030:Nitric Oxide Donors; D009712:Nucleotides, Cyclic; D018160:Receptors, Cytoplasmic and Nuclear; D016329:Sp1 Transcription Factor; D014409:Tumor Necrosis Factor-alpha; D009569:Nitric Oxide; D017868:Cyclic AMP-Dependent Protein Kinases; D062965:Cyclic GMP-Dependent Protein Kinase Type I; D017869:Cyclic GMP-Dependent Protein Kinases; C569718:PRKG1 protein, human; D006162:Guanylate Cyclase; D000071756:Soluble Guanylyl Cyclase