title: Differential regulation of extracellular matrix and soluble fibulin-1 levels by TGF-β₁ in airway smooth muscle cells.
abstract: Fibulin-1 (FBLN-1) is a secreted glycoprotein that is associated with extracellular matrix (ECM) formation and rebuilding. Abnormal and exaggerated deposition of ECM proteins is a hallmark of many fibrotic diseases, such as chronic obstructive pulmonary disease (COPD) where small airway fibrosis occurs. The aim of this study was to investigate the regulation of FBLN-1 by transforming growth factor beta 1 (TGF-β1) (a pro-fibrotic stimulus) in primary human airway smooth muscle (ASM) cells from volunteers with and without COPD. Human ASM cells were seeded at a density of 1×10(4) cells/cm(2), and stimulated with or without TGF-β1 (10 ng/ml) for 72 hours before FBLN-1 deposition and soluble FBLN-1 were measured. Fold change in FBLN-1 mRNA was measured at 4, 8, 24, 48, 72 hours. In some experiments, cycloheximide (0.5 µg/ml) was used to assess the regulation of FBLN-1 production. TGF-β1 decreased the amount of soluble FBLN-1 both from COPD and non-COPD ASM cells. In contrast, the deposition of FBLN-1 into the ECM was increased in ASM cells obtained from both groups. TGF-β1 did not increase FBLN-1 gene expression at any of the time points. There were no differences in the TGF-β1 induced FBLN-1 levels between cells from people with or without COPD. Cycloheximide treatment, which inhibits protein synthesis, decreased both the constitutive release of soluble FBLN-1, and TGF-β1 induced ECM FBLN-1 deposition. Furthermore, in cycloheximide treated cells addition of soluble FBLN-1 resulted in incorporation of FBLN-1 into the ECM. Therefore the increased deposition of FBLN-1 by ASM cells into the ECM following treatment with TGF-β1 is likely due to incorporation of soluble FBLN-1 rather than de-novo synthesis.
authors.affiliation: Key Laboratory of Biorheological Science and Technology, Ministry of Education, Bioengineering College, Chongqing University, Shapingba, Chongqing, China.
authors.forename: Ling
authors.initials: L
authors.lastname: Chen
authors.forename: Qi
authors.initials: Q
authors.lastname: Ge
authors.forename: Judith L
authors.initials: JL
authors.lastname: Black
authors.forename: Linhong
authors.initials: L
authors.lastname: Deng
authors.forename: Janette K
authors.initials: JK
authors.lastname: Burgess
authors.forename: Brian G G
authors.initials: BG
authors.lastname: Oliver
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002135:Calcium-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D003513:Cycloheximide / Q000494:pharmacology; D005109:Extracellular Matrix / Q000187:drug effects / Q000378:metabolism*; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D014176:Protein Biosynthesis / Q000187:drug effects; D029424:Pulmonary Disease, Chronic Obstructive / Q000235:genetics / Q000473:pathology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012137:Respiratory System / Q000473:pathology*; D012995:Solubility; D013347:Subcellular Fractions / Q000187:drug effects / Q000378:metabolism; D053773:Transforming Growth Factor beta1 / Q000494:pharmacology*; D055815:Young Adult
chemical_list: D002135:Calcium-Binding Proteins; D012333:RNA, Messenger; D053773:Transforming Growth Factor beta1; C060820:fibulin; D003513:Cycloheximide