Molecular characterization of two isoforms of ZFAND3 cDNA from the Japanese quail and the leopard gecko, and different expression patterns between testis and ovary.

Zing finger AN1-type domain 3 (ZFAND3), also known as testis expressed sequence 27 (Tex27), is a gene found in the mouse testis, but its physiological function is unknown. We identified the full-length sequences of two isoforms (short and long) of ZFAND3 cDNA from Japanese quail and leopard gecko. This is the first cloning of avian and reptilian ZFAND3 cDNA. The two isoforms are generated by alternative polyadenylation in the 3'UTR and have the same ORF sequences encoding identical proteins. There were highly conserved regions in the 3'UTR of the long form near the polyadenylation sites from mammals to amphibians, suggesting that the features for determining the stability of mRNA or translation efficiency differ between isoforms. The deduced amino acid sequence of ZFAND3 has two putative zinc finger domains, an A20-like zinc finger domain at the N-terminal and an AN1-like zinc finger domain at the C-terminal. Sequence analysis revealed an additional exon in the genomic structures of the avian and reptilian ZFAND3 genes which is not present in mammals, amphibians, or fish, and this exon produces additional amino acid residues in the A20-like zinc finger domain. Expression analysis in Japanese quail revealed that the expression level of ZFAND3 mRNA was high in not only the testis but also the ovary, and ZFAND3 mRNA was expressed in both spermatides of the testis and oocytes of the ovary. While the short form mRNA was mainly expressed in the testis, the expression level of the long form mRNA was high in the ovary. These results suggest that ZFAND3 has physiological functions related to germ cell maturation and regulatory mechanisms that differ between the testis and ovary.