IMMORTALIZED HENSENS NODE CELLS SECRETE A FACTOR THAT REGULATES AVIANNEURAL CREST CELL FATES IN-VITRO

The derivatives of the neural crest are regionally specified with resp ect to the anterior-posterior axis of the avian embryo. We have shown previously that young Hensen's node can act in vitro to regulate the e xpression of certain region-specific phenotypes in trunk neural crest cells. To study potential factors acting on the neural crest, we have generated an immortalized cell line from young Hensen's node. Here we show that a factor produced by these cells stimulates the expression o f two cranial-specific phenotypes (fibronectin and smooth muscle actin ) in trunk neural crest cells and decreases their expression of a trun k-specific phenotype (melanin). The active factor is a secreted protei n with a molecular weight >30 kDa. Clonal studies suggest that the fac tor acts by changing the phenotypic fates of individual neural crest c ells, rather than by selective effects on cell proliferation or surviv al. Previous work has shown that TGF-beta s can mimic the effects of H ensen's node cells on neural crest differentiation. Results from the p resent study suggest that the factor in the conditioned medium of the immortalized node cell line is not a TGF-beta isoform. However, the cr anial phenotype-inducing activity of the conditioned medium factor req uires the presence of neural crest cell-derived TGF-beta s. (C) 1996 A cademic Press, Inc.