WINGED HELIX TRANSCRIPTION FACTOR BF-1 IS ESSENTIAL FOR THE DEVELOPMENT OF THE CEREBRAL HEMISPHERES

We generated mice with a null mutation of the forebrain-restricted tra nscription factor BF-1 to examine its function in brain development. H eterozygous animals have an apparently normal phenotype. Homozygous nu ll BF-1 mutants die at birth and have a dramatic reduction in the size of the cerebral hemispheres. The development of the ventral telenceph alon is more severely affected than that of the dorsal telencephalon. Telencephalic neuroepithelial cells are specified in the BF-1 mutant, but their proliferation is reduced. Dorsal telencephalic neuroepitheli al cells also differentiate prematurely, leading to early depletion of the progenitor population. These results suggest that BF-1 controls t he morphogenesis of the telencephalon by regulating the rate of neuroe pithelial cell proliferation and the timing of neuronal differentiatio n.