MULTIPLE ELEMENTS REGULATE MASH1 EXPRESSION IN THE DEVELOPING CNS

Mash1, a transcription factor of the basic helix-loop-helix class, is expressed during embryogenesis in restricted regions of the nervous sy stem. An essential role for Mash1 in neural development was demonstrat ed previously in mice carrying a targeted disruption of the Mash1 gene . Regulation of the precise temporal and spatial expression of Mash1 i s thus likely re, be important for proper neural development. In this study, sequences that regulate Mash1 expression in the central nervous system were characterized by assaying the expression of lacZ reporter genes in transgenic embryos. A 1158-bp enhancer localized similar to 7 kb upstream of the Mash1 coding region was identified. Deletions wit hin this enhancer region reveal the presence of both positive and nega tive cls-acting elements, Analysis of multiple sequences within the en hancer demonstrate that different elements preferentially function in different regions within the Mash1-specific CNS expression domain. In addition, a role for sequences 3' of the Mash1 coding region is reveal ed, providing evidence Tor posttranscriptional control of Mash1 expres sion in multiple CNS domains. (C) 1998 Academic Press.