Worm Breeder's Gazette 14(5): 46 (February 1, 1997)
These abstracts should not be cited in bibliographies. Material contained herein should be treated as personal communication and should be cited as such only with the consent of the author.
|1||The Johns Hopkins University Biology Graduate Program, The Carnegie Institution of Washington|
|2||The Carnegie Institution of Washington|
The C. elegans genome project recently revealed the coding region for a novel basic helix-loop-helix (bHLH) factor that is similar to the twist family of transcription factors. In other systems (flies, vertebrates), the twist transcription factor is important in determining different types of muscle fate; twist protein is thought to interact with other muscle specific transcription factors to modulate muscle gene expression. To begin to understand the role of the new C. elegans bHLH gene we have done the following: 1. Identification and sequencing of a cDNA clone from a phage library. This indicates that the gene is expressed and allowed definitive assignment of the intron-exon boundaries. Inside the bHLH domain, the C. elegans gene shares 61% identity to insect twist and 59% identity to mouse and Xenopus twist (Fig.1). This identity is much closer to twist members in other species then to other C. elegans bHLH genes. The twist family is not well conserved outside of the bHLH domain, but all published twist genes have three distinct features. a) Each starts with two Met codons. b) Each has a small conserved domain just 3' of the bHLH domain. c) Each ends just after the 3' conserved domain. The C. elegans gene has none of these features. We are therefore tentatively calling the C. elegans factor Cetwist-like1. 2. Characterization of the regulatory sequences using lacZ and gfp gene fusions and tagging constructs. Both reporter fusions and gfp tagged constructs yielded a similar expression pattern (Fig.2). The Cetwist-like1 promoter is active in the M mesoblast in 3-fold stage embryos and in all M descendants until there are 16 such cells. Promoter activity is then turned off in the 14 M-derived body wall muscle cells but remains on in the two SM's and post-embryonic coelomocytes. Reporter expression can be seen in all the descendants of the SM's until the L4 to adult transition. In addition, reporter activity is seen in the 4 embryonic coelomocytes. Preliminary deletion analysis of the promoter has determined that there are distinct 5' signals for the M lineage and the coelomocytes. Future plans include making a mutation in the Cetwist-like1 gene and determining how this protein interacts with other muscle specific transcription factors like MyoD (Chen et al. Development 120:1631-1641, 1994) and CEH-24 (Fire and Harfe, WBG 13(4): 91, 1994).