title: Nitric oxide and cGMP-dependent protein kinase regulation of glucose-mediated thrombospondin 1-dependent transforming growth factor-beta activation in mesangial cells.
abstract: Excessive transforming growth factor-beta (TGF-beta) activity in hyperglycemia contributes to the development of diabetic nephropathy. Glucose stimulation of TGF-beta activity and matrix synthesis are dependent on autocrine thrombospondin 1 (TSP1) to convert latent TGF-beta to its biologically active form. The mechanisms by which glucose regulates TSP1 are not known. High glucose inhibits nitric oxide (NO) bioavailability and decreased NO increases TGF-beta activity and extracellular matrix accumulation. Yet, the impact of NO signaling on TSP1 activation of TGF-beta is unknown. We tested the role of NO signaling in the regulation of TSP1 expression and TSP1-dependent TGF-beta activity in rat mesangial cells exposed to high glucose. On exposure to 30 mm glucose, NO accumulation in the conditioned media and intracellular cGMP levels were significantly decreased. The addition of an NO donor prevented the glucose-dependent increase in TSP1 mRNA, protein, and TGF-beta bioactivity. The effects of the NO donor were blocked by ODQ (a soluble guanylate cyclase inhibitor) or Rp-8-pCPT-cGMPS (an inhibitor of cGMP-dependent protein kinase). These effects of high glucose were also reversed by the nitric-oxide synthase cofactor tetrahyrobiopterin (BH(4)). These results show that high glucose mediates increases in TSP1 expression and TSP1-dependent TGF-beta bioactivity through down-modulation of NO-cGMP-dependent protein kinase signaling.
authors.affiliation: Department of Pathology, Division of Molecular and Cellular Pathology, The Cell Adhesion and Matrix Research Center, University of Alabama, Birmingham 35294-0019, USA.
authors.forename: Shuxia
authors.initials: S
authors.lastname: Wang
authors.forename: Sruti
authors.initials: S
authors.lastname: Shiva
authors.forename: Maria H
authors.initials: MH
authors.lastname: Poczatek
authors.forename: Victor
authors.initials: V
authors.lastname: Darley-Usmar
authors.forename: Joanne E
authors.initials: JE
authors.lastname: Murphy-Ullrich
mesh_terms: D000818:Animals; D002460:Cell Line; D002478:Cells, Cultured; D006152:Cyclic GMP / Q000031:analogs & derivatives* / Q000494:pharmacology; D017869:Cyclic GMP-Dependent Protein Kinases / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005920:Glomerular Mesangium / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism* / Q000494:pharmacology; D006801:Humans; D015151:Immunoblotting; D008907:Mink; D008954:Models, Biological; D009569:Nitric Oxide / Q000096:biosynthesis / Q000378:metabolism*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D009603:Nitroso Compounds / Q000494:pharmacology; D010069:Oxadiazoles / Q000494:pharmacology; D017395:Plasminogen Activator Inhibitor 1 / Q000235:genetics; D011401:Promoter Regions, Genetic; D011810:Quinoxalines / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D015398:Signal Transduction; D013873:Thionucleotides / Q000494:pharmacology; D019700:Thrombospondin 1 / Q000378:metabolism*; D013997:Time Factors; D014162:Transfection; D016212:Transforming Growth Factor beta / Q000378:metabolism*
chemical_list: C095284:1H-(1,2,4)oxadiazolo(4,3-a)quinoxalin-1-one; C090860:8-(4-chlorophenylthio)guanosine 3',5'-cyclic monophosphorothioate; D004791:Enzyme Inhibitors; D020030:Nitric Oxide Donors; D009603:Nitroso Compounds; D010069:Oxadiazoles; D017395:Plasminogen Activator Inhibitor 1; D011810:Quinoxalines; D012333:RNA, Messenger; D013873:Thionucleotides; D019700:Thrombospondin 1; D016212:Transforming Growth Factor beta; C094210:2,2'-(hydroxynitrosohydrazono)bis-ethanamine; D009569:Nitric Oxide; D017869:Cyclic GMP-Dependent Protein Kinases; D006152:Cyclic GMP; D005947:Glucose