Making a brain

A long-standing paradigm in developmental biology has been that default neuralization (ie., the differentiation of dissociated ectodermal cells to neural cells in culture) is caused by the dilution and thereby suppression of BMP growth factor signaling. Dr. Edward De Robertis and colleagues now show that, contrary to this traditional belief, BMP signaling is, in fact, sustained at comparable levels in dissociated ectodermal cells as in intact Xenopus embryos. The researchers find that it is the activation of Ras/MAPK signaling, and subsequent cross-talk between the MAPK and BMP signaling pathways that promotes a neural fate. "The work is important because it helps explain not only how the brain is formed, but also how multiple cell signaling pathways are integrated within the cell," claims Dr. De Robertis.

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