EDA-containing cellular fibronectin induces fibroblast differentiation through binding to alpha4beta7 integrin receptor and MAPK/Erk 1/2-dependent signaling

FASEB J. 2010 Nov;24(11):4503-12. doi: 10.1096/fj.10-154435. Epub 2010 Jul 19.

Abstract

Fibroblast differentiation is an essential step during wound healing and fibrosis. Fibronectin (FN) is a major component of the extracellular matrix and occurs in two main forms: plasma and cellular FN. The latter includes the alternatively spliced domain A (EDA). Although EDA-containing cellular fibronectin (EDA-FN) is associated with fibroblast differentiation, how EDA-FN promotes differentiation is incompletely understood. In this study, we investigate the mechanism by which EDA-FN contributes to fibroblast differentiation with emphasis on the characterization of the EDA-FN receptor. We show that EDA-FN increases α-SMA expression (immunofluorescence), collagen deposition, cell contractility, and focal adhesion kinase (FAK) activation (immunoblotting); whereas plasma FN, a form lacking EDA, shows no effect. Primary lung fibroblasts constitutively express α(4)β(7) integrin receptor (FACS and RT-PCR). Blocking of α(4)β(7) reduces fibroblast adhesion to EDA-FN and inhibits α-SMA expression, collagen deposition, and FAK activation induced by EDA-FN. Using recombinant EDA-containing peptides, we demonstrate that the EDA segment is sufficient to induce fibroblast differentiation via binding to α(4)β(7). EDA-FN induces MAPK-Erk1/2 activation and inhibition of MEK1/2 attenuates EDA-FN-induced α-SMA expression. Our findings demonstrate that EDA-FN induces fibroblast differentiation by a mechanism that involves binding of EDA to α(4)β(7) integrin followed by activation of FAK and MAPK-associated signaling pathways.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actins / metabolism
  • Animals
  • Cell Adhesion
  • Cell Differentiation*
  • Cells, Cultured
  • Enzyme Activation / drug effects
  • Enzyme Activators / pharmacology
  • Extracellular Signal-Regulated MAP Kinases / metabolism*
  • Fibroblasts / cytology
  • Fibroblasts / drug effects*
  • Fibronectins / metabolism
  • Fibronectins / pharmacology*
  • Focal Adhesion Kinase 1 / metabolism
  • Integrins / metabolism*
  • Mice
  • Mice, Inbred C57BL
  • Protein Binding
  • Signal Transduction*

Substances

  • Acta2 protein, mouse
  • Actins
  • Enzyme Activators
  • Fibronectins
  • Integrins
  • integrin alpha4beta7
  • Focal Adhesion Kinase 1
  • Ptk2 protein, mouse
  • Extracellular Signal-Regulated MAP Kinases