Groucho-mediated transcriptional repression establishes progenitor cell pattern and neuronal fate in the ventral neural tube

The pattern of neuronal specification in the ventral neural tube is control led by homeodomain transcription factors expressed by neural progenitor cel ls, but no general logic has emerged to explain how these proteins determin e neuronal fate. We show that most of these homeodomain proteins possess a conserved ehl motif that mediates the recruitment of Gro/TLE corepressors. The ehl motif underlies the function of these proteins as repressors during neural patterning in vivo. Inhibition of Gro/TLE-mediated repression in vi vo results in a deregulation of cell pattern in the neural tube. These resu lts imply that the pattern of neurogenesis in the neural tube is achieved t hrough the spatially controlled repression of transcriptional repressors-a derepression strategy of neuronal fate specification.