Transforming Growth factor-β-induced Differentiation of Airway Smooth Muscle Cells Is Inhibited by Fibroblast Growth factor-2

Am J Respir Cell Mol Biol. 2013 Mar;48(3):346-53. doi: 10.1165/rcmb.2012-0151OC. Epub 2012 Dec 13.

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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actins / genetics
  • Actins / metabolism
  • Asthma / genetics
  • Asthma / metabolism
  • Asthma / pathology
  • Calcium-Binding Proteins / genetics
  • Calcium-Binding Proteins / metabolism
  • Cell Differentiation / genetics*
  • Cells, Cultured
  • Collagen / genetics
  • Collagen / metabolism
  • Contractile Proteins / genetics
  • Contractile Proteins / metabolism
  • Fibroblast Growth Factor 2 / genetics
  • Fibroblast Growth Factor 2 / metabolism*
  • Humans
  • Interleukin-6 / genetics
  • Interleukin-6 / metabolism
  • MAP Kinase Signaling System / genetics
  • Microfilament Proteins / genetics
  • Microfilament Proteins / metabolism
  • Muscle Proteins / genetics
  • Muscle Proteins / metabolism
  • Muscle, Smooth / cytology*
  • Muscle, Smooth / metabolism
  • Myocytes, Smooth Muscle / cytology*
  • Myocytes, Smooth Muscle / metabolism
  • Respiratory System / cytology*
  • Respiratory System / metabolism*
  • Serum Response Factor / genetics
  • Serum Response Factor / metabolism
  • Signal Transduction / genetics
  • Transforming Growth Factor beta / genetics
  • Transforming Growth Factor beta / metabolism*
  • ets-Domain Protein Elk-1 / genetics
  • ets-Domain Protein Elk-1 / metabolism

Substances

  • ACTA2 protein, human
  • Actins
  • Calcium-Binding Proteins
  • Contractile Proteins
  • IL6 protein, human
  • Interleukin-6
  • Microfilament Proteins
  • Muscle Proteins
  • SRF protein, human
  • Serum Response Factor
  • Transforming Growth Factor beta
  • calponin
  • ets-Domain Protein Elk-1
  • transgelin
  • Fibroblast Growth Factor 2
  • Collagen