Mode of adsorption and orientation of an extracellular matrix protein affect its cell-adhesion-promoting activity.

Cell adhesion to extracellular matrix contributes to the organization of tissues and modulates cell behavior. In conventional cell adhesion assays, plastic wells are coated with matrix proteins and assayed for their adhesion-promoting activity. We show here that factors such as sample composition, coating buffers, and manufacturers' plastic treatment markedly affect cell adhesion to the extracellular matrix protein laminin-5 (Ln-5).

Characterization of a tight molecular complex between integrin alpha 6 beta 4 and laminin-5 extracellular matrix.

In many adult epithelia, e.g., epidermis or intestine, adhesion of epithelial cells to basement membrane requires the integrin alpha6 beta4 and laminin-5 (Ln-5).

Induction of cell migration by matrix metalloprotease-2 cleavage of laminin-5.

Structural changes in the extracellular matrix are necessary for cell migration during tissue remodeling and tumor invasion. Specific cleavage of laminin-5 (Ln-5) by matrix metalloprotease-2 (MMP2) was shown to induce migration of breast epithelial cells. MMP2 cleaved the Ln-5 gamma2 subunit at residue 587, exposing a putative cryptic promigratory site on Ln-5 that triggers cell motility.

Changes in expression of monoclonal antibody epitopes on laminin-5r induced by cell contact.

Laminin-5r is a basement membrane component that promotes rapid adhesion and hemidesmosome formation in epithelial cells. We raised monoclonal antibodies and identified their corresponding epitopes on the constituent chains of laminin-5r by western blotting. Using a combination of immunoprecipitation and ELISA assays, we determined that these epitopes are differentially exposed on two forms of the laminin-5r heterotrimer: soluble (passively adsorbed onto plastic) and cell-associated.