An LRE (leucine-arginine-glutamate)-dependent mechanism for adhesion of neurons to S-laminin

摘要: S-laminin is a homolog of laminin that concentrated in the synaptic cleft neuromuscular junction. We previously showed tripeptide LRE crucial determinant for binding ciliary motoneurons to recombinant s-laminin. Here, we describe neuroblastoma-spinal neuron hybrid cell line, NSC-34, binds an LRE-containing s-laminin fragment and synthetic LRE-protein conjugate. NSC-34 cells exhibit several properties motoneurons; other lines tested were not motoneuron-like did display LRE-dependent adhesion. therefore used characterize adhesion mechanism. Inhibition studies with series 20 analogs high degree selectivity LRE, suggested ligand requires combination electrostatic hydrophobic interactions. The effects cations on are unlike those described molecules including integrins, family receptors extracellular matrix proteins, laminin. Specifically, does require divalent inhibited by Ca2+ (but Mg2+) physiological range. In contrast, LRE- independent but Mg2+ dependent, appears be mediated integrins. Additionally, experiments using mixed substrates demonstrated conjugates inhibit neurite outgrowth promoted Finally, show that, under ionic conditions minimize integrin-dependent adhesion, bind s-laminin-rich basal laminae tissue sections manner. Together, these results suggest comprises motoneuron-selective site accessible native acts outgrowth.