Telencephalon-restricted expression of BF-1, a new member of the HNF-3/fork head gene family, in the developing rat brain.

We have previously characterized a novel transcription factor family in mammals, the HNF-3 family, by the members' homology to one another and to the Drosophila homeotic gene fork head. The expression of fork head is restricted to the anterior and posterior termini of the early fly embryo. Brain factor 1 (BF-1) is a new member of this family isolated from rat brain with an expression pattern and DNA binding specificity distinct from the HNF-3 genes. Expression is highly restricted in the developing neural tube to its rostral end, which gives rise to the telencephalon. These results suggest that BF-1 plays an important role in the establishment of the regional subdivision of the developing brain and in the development of the telencephalon.