Neuregulin, a factor with many functions in the life of a Schwann cell

The signalling system comprising the ligand Neuregulin-1,and its receptors, ErbB2 and ErbB3, plays multiple and important roles in glial development. These include functions in early development of neural crest cells, in expa nsion of the Schwann cell precursor pool and in myelination. Neuregulin is one of the crucial axon-derived signals that influence development of Schwa nn cells. These are specialized cells that ensheath peripheral axons and pr ovide electrical insulation. Schwann cells have also long been implicated i n providing more than a simple ensheathing function. Compelling evidence fo r this has emerged from the analysis of mice lacking these cells, resulting from a non-functional or compromised Neuregulin signalling system. They se rve as a model to study glia-nerve interactions in vivo and indicate that S chwann cells provide important neurotrophic signals, and also cues that reg ulate perineurium development and nerve fasciculation. BioEssays 22:987-996 , 2000. (C) 2000 John Wiley & Sons, Inc.