Worm Breeder's Gazette 13(2): 60 (February 1, 1994)

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.

c. elegans homologs of MEF-2 ,muscle-specific transcription factors.

Daryl Dichoso, Michael Krause

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LMB/NIDDK, National Institutes of Health, Bethesda, MD.

MEF-2 ,(formyocyte-enhancer-binding-factor), is a muscle-restricted, sequence-specific transcription factor known to participate in the regulation of many muscle genes. In vertebrates, MEF-2 binding sites have been demonstrated for both terminally expressed gene products (such as muscle creatine kinase) and MyoD Family members (MyoD and myogenin). Recent results suggest that MEF-2 may play a more important role in myogenic cell fate determination than originally thought. Expression of certain isoforms of MEF-2 occurs in early muscle precursors during development in mouse, Xenopus, and Drosophila. In Drosophila, expression of a MEF-2 clone occurs prior to expression of the MyoD Family homolog nautilus and occurs in cells that are precursors for visceral and skeletal muscle cells (Brenda Lilly and Eric Olson).

MEF-2 is a member of a larger group of transcription factors that are know as the MADS Family (MCM1, Agamous, Deficiens, and Serum response factor). MADS Family members share a conserved domain spanning about 55 amino acids at the amino terminal end of the protein. The MADS domain is involved in both dimerization and DNA binding of these transcription factors.

The conservation of the MADS domain makes these genes good targets for PCR cloning; so we did. We used degenerate oligonucleotides in RT-PCR reactions of worm total RNA. The clones isolated are listed below; they each are related to MEF-2 and demonstrate that MADS box proteins are present in worms. The sequence results suggest as many as five different MEF-2 gene products. We are presently screening a C. elegans cDNA library with the partial sequence of MEF-2 initially obtained and are also attempting to amplify flanking sequences of the same partial sequence of MEF-2 .We want to know when and where these genes are expressed and how their expression is related to myogenesis in the worm.

Figure 1