title: Transforming growth factor-β-induced differentiation of airway smooth muscle cells is inhibited by fibroblast growth factor-2.
abstract: In asthma, basic fibroblast growth factor (FGF-2) plays an important (patho)physiological role. This study examines the effects of FGF-2 on the transforming growth factor-β (TGF-β)-stimulated differentiation of airway smooth muscle (ASM) cells in vitro. The differentiation of human ASM cells after incubation with TGF-β (100 pM) and/or FGF-2 (300 pM) for 48 hours was assessed by increases in contractile protein expression, actin-cytoskeleton reorganization, enhancements in cell stiffness, and collagen remodeling. FGF-2 inhibited TGF-β-stimulated increases in transgelin (SM22) and calponin gene expression (n = 15, P < 0.01) in an extracellular signal-regulated kinase 1/2 (ERK1/2) signal transduction-dependent manner. The abundance of ordered α-smooth muscle actin (α-SMA) filaments formed in the presence of TGF-β were also reduced by FGF-2, as was the ratio of F-actin to G-actin (n = 8, P < 0.01). Furthermore, FGF-2 attenuated TGF-β-stimulated increases in ASM cell stiffness and the ASM-mediated contraction of lattices, composed of collagen fibrils (n = 5, P < 0.01). However, the TGF-β-stimulated production of IL-6 was not influenced by FGF-2 (n = 4, P > 0.05), suggesting that FGF-2 antagonism is selective for the regulation of ASM cell contractile protein expression, organization, and function. Another mitogen, thrombin (0.3 U ml(-1)), exerted no effect on TGF-β-regulated contractile protein expression (n = 8, P > 0.05), α-SMA organization, or the ratio of F-actin to G-actin (n = 4, P > 0.05), suggesting that the inhibitory effect of FGF-2 is dissociated from its mitogenic actions. The addition of FGF-2, 24 hours after TGF-β treatment, still reduced contractile protein expression, even when the TGF-β-receptor kinase inhibitor, SB431542 (10 μM), was added 1 hour before FGF-2. We conclude that the ASM cell differentiation promoted by TGF-β is antagonized by FGF-2. A better understanding of the mechanism of action for FGF-2 is necessary to develop a strategy for therapeutic exploitation in the treatment of asthma.
authors.affiliation: Department of Pharmacology, University of Melbourne, Grattan St., Parkville, Victoria 3010, Australia.
authors.forename: Michael
authors.initials: M
authors.lastname: Schuliga
authors.forename: Aqeel
authors.initials: A
authors.lastname: Javeed
authors.forename: Trudi
authors.initials: T
authors.lastname: Harris
authors.forename: Yuxiu
authors.initials: Y
authors.lastname: Xia
authors.forename: Chengxue
authors.initials: C
authors.lastname: Qin
authors.forename: Zhexing
authors.initials: Z
authors.lastname: Wang
authors.forename: Xuehua
authors.initials: X
authors.lastname: Zhang
authors.forename: Peter V S
authors.initials: PV
authors.lastname: Lee
authors.forename: Blanca
authors.initials: B
authors.lastname: Camoretti-Mercado
authors.forename: Alastair G
authors.initials: AG
authors.lastname: Stewart
mesh_terms: D000199:Actins / Q000235:genetics / Q000378:metabolism; D001249:Asthma / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D002135:Calcium-Binding Proteins / Q000235:genetics / Q000378:metabolism; D002454:Cell Differentiation / Q000235:genetics*; D002478:Cells, Cultured; D003094:Collagen / Q000235:genetics / Q000378:metabolism; D003285:Contractile Proteins / Q000235:genetics / Q000378:metabolism; D016222:Fibroblast Growth Factor 2 / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D015850:Interleukin-6 / Q000235:genetics / Q000378:metabolism; D020935:MAP Kinase Signaling System / Q000235:genetics; D008840:Microfilament Proteins / Q000235:genetics / Q000378:metabolism; D009124:Muscle Proteins / Q000235:genetics / Q000378:metabolism; D009130:Muscle, Smooth / Q000166:cytology* / Q000378:metabolism; D032389:Myocytes, Smooth Muscle / Q000166:cytology* / Q000378:metabolism; D012137:Respiratory System / Q000166:cytology* / Q000378:metabolism*; D026362:Serum Response Factor / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics; D016212:Transforming Growth Factor beta / Q000235:genetics / Q000378:metabolism*; D050807:ets-Domain Protein Elk-1 / Q000235:genetics / Q000378:metabolism; D000096985:Calponins
chemical_list: D000199:Actins; D002135:Calcium-Binding Proteins; D003094:Collagen; D003285:Contractile Proteins; D016222:Fibroblast Growth Factor 2; D015850:Interleukin-6; D008840:Microfilament Proteins; D009124:Muscle Proteins; D026362:Serum Response Factor; D016212:Transforming Growth Factor beta; D050807:ets-Domain Protein Elk-1; D000096985:Calponins; C541116:ACTA2 protein, human; C508600:IL6 protein, human; C476858:SRF protein, human; C051615:transgelin