Effects of decorin and biglycan on human airway smooth muscle cell adhesion

Growth on a decorin matrix results in decreased human airway smooth muscle cell (HASMC) number, by decreasing proliferation and increasing apoptosis. We questioned whether these effects were related to abnormal extracellular matrix (ECM)-cell adhesion. HASMCs were seeded on decorin, biglycan, collagen type I or plastic. Actin organization and focal adhesion formation were assessed by staining for filamentous (F) and globular (G) actin, and vinculin, respectively. Gene expression for focal adhesion proteins, ECM molecules and HASMC receptors was measured. Protein levels for fibronectin, α2, α5, αv and β3 integrin subunits and, focal adhesion kinase (FAK) were assessed. F-actin filaments were prominent in cells seeded on collagen I and plastic, less apparent in cells cultured on biglycan and faint in cells on decorin. Vinculin clustering was decreased in cells seeded on decorin and biglycan, as was vinculin gene expression. Compared to cells on plastic, cells on decorin had an increase in fibronectin gene expression. Seeding on decorin caused an increase in α2 integrin subunit and platelet-derived growth factor receptor A gene expression. There was also an increase in α2 and αv integrin subunit protein. Finally, FAK protein levels in cells seeded on decorin or biglycan were decreased compared to cells seeded on plastic or collagen I. Cells grown on proteoglycan matrices demonstrate evidence of abnormalities during many of the key processes involved in normal cell adhesion. Upregulation of cell surface receptor proteins, such as α2 integrin subunit, may represent a compensatory mechanism to overcome poor adhesion induced by growth on these matrices.

► We studied how decorin and biglycan affect human airway smooth muscle cell adhesion.
► Decorin (dcn) and biglycan (bgn) reduce actin filament and focal adhesion formation.
► Dcn and bgn alter vinculin, fibronectin, α2 integrin and PDGRA gene expression.
► Dcn and bgn increase α2 and αv integrin and reduce focal adhesion kinase protein.
► Dcn and bgn affect cell adhesion, which may lead to alterations in cell function.