The leukemic oncogene tal-2 is expressed in the developing mouse brain

tal-1 (T-cell acute leukemia-1; also known as SCL) and tal-2 genes belong t o a family of basic helix-loop-helix transcription factors and were origina lly isolated from the breakpoints of chromosomal translocations in human T- cell leukemia cell lines, tal-1 is expressed not only in hematopoietic cell s but also in several endothelial structures and the central nervous system during development. On the other hand, the detailed function and the sites of expression of tal-2 have remained obscure. We cloned the tal-2 cDNA fro m a mouse embryonic cDNA library and examined its expression pattern in the mouse, comparing with that of tal-1. In situ analyses revealed that tal-2 transcripts are detected at embryonic day 12.5 in the following regions; 1) the diencephalon-the zona limitans intrathalamica and the pretectum, 2) th e mesencephalon-the tectum, and the anterior and posterior tegmentum, 3) th e metencephalon-the isthmus and the anterior pens. In the diencephalon and the mesencephalon, the expression sites of tal-2 gene were similar to those of tal-1, and its expression was stronger than that of tal-1. In the meten cephalon, tal-2 expression was observed in the anterior pens, whereas tal-1 transcripts were detected in the entire pens, and showed stronger expressi on than tal-2. The tal-2 messages were barely detectable in the brain at bi rth. These results suggest that tal-1 and tal-2 are involved in the develop ment of specific areas of the central nervous system. (C) 1999 Elsevier Sci ence B.V. All rights reserved.