Zinc finger-containing transcription factors have been documented in the regulation of gene transcription in a number of developmental models. We have identified two zinc finger proteins, W06H12.1 and Y40B1A.4, both of which have three conserved C2H2 zinc finger domains. These proteins appear to be essential for the differentiation of the male tail region where nine pairs of sensory rays with distinct identities reside. We previously reported that mab-21
is required for the specification of the ray 6 identity. In a yeast two-hybrid screen with MAB-21 protein bait, W06H12.1 was first identified. W06H12.1 product has 380 amino acids with three C2H2 zinc finger domains and two putative nuclear localization signal sequences. RNAi experiments showed that knock-down of this gene resulted in ray fusion and occasional Mab-21 phenotype. By reporter assay with a 1.5kb promoter region in transgenic animals, W06H12.1 was found to be expressed in hypodermis, seam from embryonic to larval stage. In adults, expression in the hermaphrodite vulva and male tail ray structural cells were also observed. We further demonstrated that the W06H12.1 promoter region driving a mab-21
cDNA could rescue mab-21
mutant effectively, suggesting that the two genes have overlapping temporal and spatial expression patterns and may act together in the ray 6 determination process. W06H12.1 protein have been overexpressed in bacteria and the purified protein will be used for identify target DNA binding sites in the genome. The results of this experiment may lead to the identification of target genes important of the ray 6 structural cell differentiation. Y40B1A.4 obtained in the same genetic screen appeared to play a different role in ray differentiation. Male animals subjected to RNAi treatment showed extensive ray loss phenotype, as observed in mutant lin-32
males. In addition, it displayed a slightly uncoordinated and dumpy phenotype. Using specific gfp markers of the ray structural cells and neuronal cells, we showed that the ray loss phenotype was caused primarily by abnormal ray cell lineage and potential defective structural cell function. The characterization of Y40B1A.4 expression profile is in progress. The analysis of this gene and its relationship with other genes controlling ray formation may yield new insight into the detail control of ray cell assembly process.