α7β1 integrin is a receptor for laminin-2 on Schwann cells

The Schwann cell basal lamina acts as an organizer of peripheral nerve tissue and influences many aspects of cell behavior during development and regeneration. A principal component of the Schwann cell basal lamina is laminin-2. This study was undertaken to identify Schwann cell receptors for laminin-2. We found that among several Schwann cell integrins that can potentially interact with laminin-2, only α7β1 bound to laminin-2-Sepharose. Dystroglycan, a non-integrin Schwann cell receptor for laminin-2 identified previously, was also found to bind to laminin-2-Sepharose. Antibody to the α7 integrin subunit partially inhibited Schwann cell adhesion to laminin-2. Small interfering RNA-mediated suppression of either α7 integrin or dystroglycan expression decreased adhesion and spreading of Schwann cells on laminin-2, whereas knocking down both proteins together inhibited adhesion and spreading on laminin-2 almost completely. α7 integrin and dystroglycan both colocalized with laminin-2 containing basal lamina tubes in differentiating neuron–Schwann cell cocultures. The α7β1 integrin also coprecipitates with focal adhesion kinase in differentiating cocultures. These findings strongly suggest that α7β1 integrin is a Schwann cell receptor for laminin-2 that provides transmembrane linkage between the Schwann cell basal lamina and cytoskeleton. © 2007 Wiley-Liss, Inc.