title: Transcriptional and posttranscriptional regulators of biglycan in cardiac fibroblasts.
abstract: Biglycan, a small leucine-rich proteoglycan, is essential for scar formation and preservation of hemodynamic function after myocardial infarction, as shown in biglycan-knockout mice. Because of this important role in cardiac pathophysiology, we aimed to identify regulators of biglycan expression and posttranslational modifications in cardiac fibroblasts. Cardiac fibroblasts were isolated from neonatal Wistar-Kyoto rats and used in the first passage. Expression of biglycan was analyzed after metabolic labeling with [(35)S]-sulfate by SDS-polyacrylamide gel electrophoresis and molecular sieve chromatography; mRNA expression was examined by Northern analysis and real-time RT-PCR. Serum, thrombin, transforming growth factor beta1 (TGFbeta 1) and platelet-derived growth factor BB (PDGF-BB) strongly increased [(35)S]-labeled proteoglycan levels. Tumor necrosis factor alpha further increased the stimulatory effect of PDGF-BB. PDGF-BB increased glycosaminoglycan (GAG) chain length as shown by molecular sieve chromatography after beta-elimination to release GAG chains. Nitric oxide was the only negative regulator of biglycan as evidenced by marked downregulation in response to DETA-NO ((Z)-1-[2-(2-aminoethyl)-N-(2-ammonioethyl)amino]diazen-1-ium-1,2-diolate), a long acting nitric oxide donor and SNAP (S-nitroso-N-acetyl-l,l-penicillamine), which completely inhibited PDGF-BB-induced secretion of total [(35)S]-labeled proteoglycans and biglycan mRNA expression. Of note, the molecular weight of biglycan GAG chains was even further increased by NO donors compared to control and PDGF-BB stimulation. The current results suggest that in cardiac fibroblasts, biglycan is induced by a variety of stimuli including serum, thrombin and growth factors such as PDGF-BB and TGFbeta1. This response is counteracted by NO and enhanced by TNFalpha. Interestingly, both up- and downregulation were associated with posttranslational increase of GAG chain length.
authors.affiliation: Institut für Pharmakologie, Universitätsklinikum Essen, Universität Duisburg-Essen, Hufelandstrasse 55, 45147, Essen, Germany.
authors.forename: Karen
authors.initials: K
authors.lastname: Tiede
authors.forename: Ariane
authors.initials: A
authors.lastname: Melchior-Becker
authors.forename: Jens W
authors.initials: JW
authors.lastname: Fischer
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D000077214:Becaplermin; D058578:Biglycan; D002478:Cells, Cultured; D016326:Extracellular Matrix Proteins / Q000378:metabolism*; D005347:Fibroblasts / Q000378:metabolism*; D006025:Glycosaminoglycans / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism; D010982:Platelet-Derived Growth Factor / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D011509:Proteoglycans / Q000378:metabolism*; D020574:Proto-Oncogene Proteins c-sis; D051381:Rats; D011921:Rats, Inbred WKY; D013917:Thrombin / Q000378:metabolism; D053773:Transforming Growth Factor beta1 / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: C546885:Bgn protein, mouse; D058578:Biglycan; D016326:Extracellular Matrix Proteins; D006025:Glycosaminoglycans; D010982:Platelet-Derived Growth Factor; D011509:Proteoglycans; D020574:Proto-Oncogene Proteins c-sis; D053773:Transforming Growth Factor beta1; D014409:Tumor Necrosis Factor-alpha; D000077214:Becaplermin; D009569:Nitric Oxide; D013917:Thrombin