Epithelial cell motility on laminin-5: regulation by matrix assembly, proteolysis, integrins and erbB receptors.

Cell migration plays a central role in a wide variety of biological events, including embryogenesis, inflammatory immune response, wound healing, or cancer invasion. Tight regulation of cell motility is a prerequisite for normal development and maintenance of an organism, and to avoid metastatic spread of tumor cells. An important determinant of migratory efficiency is the substrate over which a cell migrates. Laminin-5 (Ln-5) is an extracellular matrix component prominent in basement membranes and as such it is a substrate in direct contact with epithelial cells. Interestingly, Ln-5 has been shown to both stimulate and downregulate epithelial cell migration. In this article, we plan to give an overview on the different mechanisms cells employ to regulate their migratory behavior on Ln-5. We will discuss how proteolytic processing of Ln-5 acts as posttranslational modification that plays a major role in the regulation of cell migration. The different proteolytic Ln-5 species may bind to distinct cell surface receptors called integrins, which translate substrate binding into a specific cellular response that triggers cell motility. Furthermore, interaction between Ln-5-binding integrins and other transmembrane and cytoplasmic proteins increases complexity and may allow fine-tuning of cell migration in response to the cellular environment.