In silico study of a novel gene evolved from an ancestral SVIP gene and highly expressed in the adult mouse testes.

We found that a cDNA clone isolated from a mouse testis cDNA library, 1700015G11 (Mmu_15G11), corresponded to the most highly expressed testis-specific mRNA in the adult mouse. Although the Mmu_15G11 cDNA is predicted to encode a small protein consisting of 67 amino acid residues, it has not yet been functionally annotated and has been designated as an unclassifiable clone. Since the Mmu_15G11 protein possibly has a pivotal role in spermatogenesis, we initiated an in silico study of this clone, and revealed that an ancestral gene of 15G11 genes evolved from an ancestral gene for mammalian small valosin-containing protein-interacting protein (SVIP) genes by gene duplication. Although SVIP protein reportedly participates in endoplasmic reticulum-related protein degradation, 15G11 protein is predicted to be a nuclear protein and possibly participates in the interaction between proteins and nuclear DNA.

In silico study of whey-acidic-protein domain containing oral protease inhibitors.

Since whey-acidic-protein domain (WAP) containing protease inhibitors such as SLPI (secretory leukocyte protease inhibitor) and elafin (elastase-specific inhibitor) have antimicrobial activities and are thought to play critical roles in mucosal defenses, we are interested in these protease inhibitors. By accessing the Novartis mouse expression database, we found that the four WAP family members, SLPI, WFDC2, WFDC5, and WFDC12, are highly expressed in the oral organs, such as the trachea, tongue, and salivary glands. Since their WAP domains play pivotal roles in the antimicrobial and/or antiprotease activities and their application in therapeutics are expected to have practical value, we collected 98 WAP homologues and tried to predict their physiological functions by analyzing their amino acid sequence structures. From the multiple alignments of amino acid sequences, we predicted that most of the mammalian N-terminal WAP domains derived from SLPIs and the WAP domains derived from WFDC12s have antimicrobial activities, whereas most of the mammalian C-terminal WAP domains derived from SLPIs and the WAP domains derived from elafins have antiprotease activities. From the phylogenetic tree, it was revealed that an ancestral WAP protein initially diverged into the WFDC5-C WAP domain and the ancestral protein for the other WAP domains. Subsequently, the ancestral protein for the other WAP domains diverged into two ancestral proteins, one for elafin and SLPI-C WAP domains and the other, for SLPI-N, WFDC15b, WFDC12, and WFDC5-N WAP domains, respectively. Moreover, the tree indicated that the WFDC5-N and WFDC12 WAP domains share a common ancestral protein.