Avian transitin expression mirrors glial cell fate restrictions during neural crest development

During development, trunk neural crest cells give rise to three primary cla sses of derivatives: glial cells, melanocytes, and neurons. As part of an e ffort to learn how neural crest diversification is regulated, we have produ ced monoclonal antibodies (MAbs) that recognize antigens expressed by neura l crest cells early in development. One of these, MAb 7B3 (7B3), was found to recognize an avian transitin-like protein by co-immunostaining with a se ries of transitin-specific monoclonal antibodies and by Western blot analys is. In neural crest cell cultures, we found that 7B3 initially recognizes t he majority of neural crest cells as they emerge from the neural tube. Subs equently, 7B3-immunoreactivity (IR) is progressively restricted to a smalle r subpopulation of cells. In fully differentiated trunk neural crest cell c ultures, 7B3-IR is expressed only by cells that do not express neuronal mar kers and lack melanin granules. During development in vivo, 7B3-IR is evide nt in neural crest cells on the medial, but not the lateral migration pathw ay, suggesting that it is not expressed by melanocyte precursors. Later, th e antigen is detected in non-neuronal, presumptive glial cells in dorsal ro ot ganglia (DRG) and sympathetic ganglia, as well as along ventral roots. C ultures of E5 DRG confirm that 7B3-IR is restricted to non-neuronal cells o f ganglia, many of which closely associate with neuronal processes, Therefo re, of the three major classes of differentiated trunk neural crest derivat ives, 7B3 exclusively recognizes glial cells, including both satellite glia and Schwann cells. Since the pattern of 7B3 expression in vitro mirrors th e pattern of glial cell fate-restrictions in the trunk neural crest lineage , and is expressed by neural crest-derived glia in vivo, we conclude that 7 B3 is an early pan-glial marker for neural crest-derived glial cells and th eir precursors. (C) 2000 Wiley-Liss, Inc.