ROLE OF THE TRANSFORMING GROWTH-FACTOR-BETA FAMILY IN THE EXPRESSION OF CRANIAL NEURAL CREST-SPECIFIC PHENOTYPES

Cranial and trunk neural crest cells produce different derivatives es in vitro, Cranial neural crest cultures produce large numbers of cells expressing fibronectin (FN) and procollagen I (PCol I) immunoreactivi ties, two markers expressed by mesenchymal derivatives in vivo, Trunk neural crest cultures produce relatively few FN or PCol I immunoreacti ve cells, but they produce greater numbers of melanocytes than do cran ial cultures. Treatment of trunk neural crest cultures with transformi ng growth factor-beta 1 (TGF-beta) stimulates them to express both FN and PCol I immunoreactivities at levels comparable to those normally s een in cranial cultures and simultaneously decreases their expression of melanin, These observations raised the possibility that endogenous TGF-beta is involved in specifying differences in the phenotypes expre ssed by cranial and trunk neural crest cells in vitro. Consistent with this idea, He found that treatment of cranial cultures with a functio n-blocking TGF-beta antiserum inhibits the development of FN immunorea ctive cells and stimulates the development of melanocytes. Cranial and trunk neural crest cells express approximately equal levels of TGF-be ta mRNA. However, trunk neural crest cells are significantly less sens itive to the FN-inducing effect of TCF-beta 1 than are cranial neural crest cells, These results suggest that: (1) endogenous TGF-beta is re quired for the expression of mesenchymal phenotypes by cranial neural crest cells, and (2) differences in the phenotypes expressed by crania l and trunk neural crest cells in vitro result in part from difference s in the sensitivities of these two cell populations to TGF-beta. (C) 1995 John Wiley & Sons, Inc.