We are investigating C. elegans homologs of the Ets family of transcription factors. In particular, we are focusing on members of the Elf subfamily. In humans, elf genes have been implicated in regulatory roles including development, immune function and tumorigenesis. For instance, the human
elf-1 gene induces T cell-specific gene expression during T cell activation and maturation. Moreover,
elf-2 has been implicated in T cell leukemia, and the amplification or up-regulation of the epithelial-specific,
elf-3 gene may be involved in breast cancer. By developing a simple genetic model, we aim to study the biological function of members of this interesting elf subfamily and to identify interacting factors. In a reverse genetic approach, we used a PCR-based screen of a frozen worm library to isolate worms carrying specific genomic insertions of the Tc1 transposon. Our screen identified the presence of a Tc1 insertion between the pointed and ets domains of the putative C. elegans homolog of human
elf-3 , designated F22A3.1. We have since isolated a line homozygous for the Tc1 insertion that will next be amplified to construct a sublibrary of insertion worms. Using a similar PCR assay, this sublibrary will be screened for deletions in F22A3.1. Deletions are produced at a low frequency, when DNA flanking the Tc1 transposon is lost as it excises from the gene. An F22A3.1 mutant may provide insight into the function of F22A3.1 in vivo and may allow enhancer and suppressor screens for interacting genes. Furthermore, in expression studies, we made green fluorescent protein (GFP) reporter constructs driven by the predicted promoters of F22A3.1 and another elf -related gene, C33A11.4. To date, we generated transgenic worm lines from the first construct. Our results suggest that F22A3.1 expression is restricted to hypodermal precursor cells during the developing larval stages and is specific to hypodermal tissues in the adult worm. Sequencing of cDNA's and 5' RACE was performed to determine the exon/intron structure of F22A3.1 and C33A11.4. For future studies we are preparing reagents for dsRNA interference, overexpression and mutant rescue.