Potential roles of N-glycosylation in cell adhesion

The functional units of cell adhesion are typically multiprotein complexes made up of three general classes of proteins; the adhesion receptors, the cell-extracellular matrix (ECM) proteins, and the cytoplasmic plaque/peripheral membrane proteins. The cell adhesion receptors are usually transmembrane glycoproteins (for example E-cadherin and integrin) that mediate binding at the extracellular surface and determine the specificity of cell-cell and cell-ECM recognition. E-cadherin-mediated cell-cell adhesion can be both temporally and spatially regulated during development, and represents a key step in the acquisition of the invasive phenotype for many tumors. On the other hand, integrin-mediated cell-ECM interactions play important roles in cytoskeleton organization and in the transduction of intracellular signals to regulate various processes such as proliferation, differentiation and cell migration. ECM proteins are typically large glycoproteins, including the collagens, fibronectins, laminins, and proteoglycans that assemble into fibrils or other complex macromolecular arrays. The most of these adhesive proteins are glycosylated. Here, we focus mainly on the modification of N-glycans of integrins and laminin-332, and a mutual regulation between cell adhesion and bisected N-glycan expression, to address the important roles of N-glycans in cell adhesion.