A MAMMALIAN HELIX-LOOP-HELIX FACTOR STRUCTURALLY RELATED TO THE PRODUCT OF DROSOPHILA PRONEURAL GENE ATONAL IS A POSITIVE TRANSCRIPTIONAL REGULATOR EXPRESSED IN THE DEVELOPING NERVOUS-SYSTEM

We report the molecular characterization of a mouse basic helix-loop-h elix factor, designated MATH-1, structurally related to the product of the Drosophila proneural gene atonal. MATH-1 mRNA is first detected i n the cranial ganglions and the dorsal part of the central nervous sys tem on embryonic day 9.5 (E9.5). From E10.5 onward, prominent expressi on of MATH-1 continues in the dorsal part of the central nervous syste m but becomes restricted to the external granular layer of the cerebel lum by E18 and is undetectable in the adult nervous system. MATH-1 act ivates E box dependent transcription in collaboration with E47, but th e activity is completely antagonized by the negative regulator of neur ogenesis HES-1. These results suggest that MATH-1 may be a target of H ES-1 and play a role in the differentiation of subsets of neural cells by activating E box-dependent transcription.