EDA-containing cellular fibronectin induces fibroblast differentiation through binding to alpha4beta7 integrin receptor and MAPK/Erk 1/2-dependent signaling.
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.
Kohan
Martin
M
Institute of Pulmonology, Hadassah-Hebrew University Medical Center, Jerusalem, Israel.
Muro
Andres F
AF
White
Eric S
ES
Berkman
Neville
N
D000199:Actins / Q000378:metabolism; D000818:Animals; D002448:Cell Adhesion; D002454:Cell Differentiation; D002478:Cells, Cultured; D004789:Enzyme Activation / Q000187:drug effects; D020536:Enzyme Activators / Q000494:pharmacology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects*; D005353:Fibronectins / Q000378:metabolism / Q000494:pharmacology*; D051417:Focal Adhesion Kinase 1 / Q000378:metabolism; D016023:Integrins / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D011485:Protein Binding; D015398:Signal Transduction
C558396:Acta2 protein, mouse; D000199:Actins; D020536:Enzyme Activators; D005353:Fibronectins; D016023:Integrins; C071777:integrin alpha4beta7; D051417:Focal Adhesion Kinase 1; C496051:Ptk2 protein, mouse; D048049:Extracellular Signal-Regulated MAP Kinases