The characteristic features of neuronal cells are constructed by neuronal specific proteins. Expression of genes encoding these factors is probably regulated by specific transcription factor(s). To understand how expression of
unc-18, one of neuronal genes is regulated, we analyzed
unc-18 promoter region. Through deletion analyses, we identified the minimal regulatory 19-bp sequence element of 250 bp upstream from the ATG start codon. Using this sequence as a probe, we identified proteins bound in expression library screening. One of these proteins, F09G2.9 contains AT hook motif, which is a peptide domain of the HMG protein that interacts with AT-sequence. In order to know the functional significance in
unc-18 expression, we used the feeding-RNAi method. In F09G2.9 (RNAi) animals, the expression of
unc-18 was suppressed, suggesting that F09G2.9 positively regulates the
unc-18 gene expression. A F09G2.9::GFP transgene with 0.7 kb of upstream sequence was expressed in head neurons, ventral nerve code and tail neurons, whose expression is similar to that of
unc-18::GFP. To examine the protein property F09G2.9 was expressed in HEK293 cells as FLAG fusion protein. By SDS-PAGE analysis of the products, two major bands were detected at around 80 kDa and 85 kDa far larger than predicted molecular weight, suggesting that this protein may be modified by phosphorylation or others. We are in the process of producing anti-F09G2.9 specific antibody and isolating a deletion mutant.