Myelin formation by Schwann cells in the absence of beta 4 integrin

The interaction of the Schwann cell with its basal lamina has been hypothes ized to be an important prerequisite for the formation of a myelin sheath i n the peripheral nervous system. One possible player in this interaction is beta 4 integrin; it is up-regulated during myelin formation and, in associ ation with alpha 6 integrin, can interact with particular components of the Schwann cell basal lamina. In order to characterize the functional roles o f beta 4 integrin during myelination, we investigated myelination in the ab sence of beta 4 integrin, i.e., in peripheral nerve tissue from beta 4 inte grin-deficient mice. Because the mutants die within several hours after bir th, we cultured dorsal root ganglia from neonatal mutants under conditions that promote myelination, quantified the myelin segments by immunofluoresce nce, and investigated the ultrastructure of the cultured myelin sheaths. In another approach, we quantified the few myelin sheaths that are detectable in femoral nerves of newborn animals. Based on both approaches, we conclud e that myelination by Schwann cells can occur in the absence of beta 4 inte grin demonstrating that this Schwann cell component is dispensable for myel in formation in peripheral nerves. GLIA 27:269-274, 1999. (C) 1999 Wiley-Li ss, Inc.