Gated migration: neurons migrate on but not onto substrates containing S-laminin.

Components of the extracellular matrix influence migration of diverse cell types. Some, such as laminin, promote neuronal migration, whereas others are nonpermissive or inhibitory. Here, we demonstrate that a recombinant fragment of s-laminin, a homologue of the laminin B1 chain, is a barrier to neuronal migration. NSC-34 (motoneuron-like) and ciliary ganglion cells were plated on substrates coated with alternating stripes of laminin and a mixture of laminin plus s-laminin. On these patterned substrates, cells seldom crossed from s-laminin-free to s-laminin-containing regions. Mutation of the tripeptide LRE, an adhesive site in s-laminin, abolished s-laminin's ability to block border crossing. However, overall rates of migration were similar on the two substrates. This behavior contrasts with that of previously reported barrier molecules, which decreases rates of cell migration when mixed with permissive substrates. Instead, s-laminin appears to block cell migration through a "gating" mechanism that acts primarily at borders.