Wounds quiet basal cells

Speed from recycling n page 545, Strachan and Condic show that neural crest cells (NCCs) can be speedy if they remember to recycle receptors. The speed gained from their conservation efforts may expose them to differentiation pathways that other NCCs miss out on. Populations of NCCs differ in their speed on various matrices. Cranial NCCs, for instance, pick up speed on higher concentrations on laminin, whereas trunk NCCs keep a slow pace. The new results show that the cranial population is able to move quickly because they both recycle and reduce the numbers of their laminin-binding integrin receptors. More laminin might actually slow cells by promoting strong adhesions. But cranial NCCs avoided this slowdown by removing laminin receptors (integrin 6) from the cell surface. The removed 6 receptors were internalized into recycling endosomes and sent back to the surface. Through this recycling pathway, receptors that are freed from adhesions at the trailing edge may be quickly moved to the leading edge, where new adhesions are needed. Indeed, inhibition of 6 receptor recycling slowed NCC migration on high concentrations of laminin, but had no affect on low laminin levels. On fibronectin, which binds to integrin 5, the surface levels of integrins 5 and 6 were unchanged, and 5 recycling was not increased. The lack of O