Tescalcin, a novel gene encoding a putative EF-hand Ca2+-binding protein, Col9a3, and renin are expressed in the mouse testis during the early stagesof gonadal differentiation

To identify genes that are differentially expressed in the developing testi s we used representational difference analysis of complementary DNA from go nads of mouse embryos at 13.5 days postcoitum (dpc). Three genes were ident ified. One of them was a novel gene termed tescalcin that encoded a putativ e EF-hand Ca2+-binding protein. The open reading frame consisted of 642 nuc leotides encoding a protein with 214 amino acids. Analysis of the predicted amino acid sequence revealed an N-myristoylation motif and several phospho rylation sites in addition to an EF-hand Ca2+-binding domain. Tescalcin mes senger RNA (mRNA) was present in fetal testis, but not in ovary or mesoneph ros, and was restricted to the testicular cords. Its expression was first d etected in the male gonad at 11.5 dpc and demonstrated a pattern consistent with a role in the testis at the early stages of testis differentiation. T escalcin is expressed in the testis of Kit(W/W-v) mice, indicating that it is not dependent on the presence of germ cells. The other two genes identif ied were collagen IX alpha3 (Col9a3) and Renin. Col9a3 expression was prese nt at low levels in male and female gonads at 11.5 dpc. Thereafter, it was markedly up-regulated in the male, but remained very low in the female. Exp ression of Col9a3 was restricted to testicular cords and was also detected in testis of Kit(W/W-v) mice. Renin mRNA was first detected in testis at 12 .5 dpc, increased thereafter, and reached a peak at 16.5 dpc. Renin mRNA wa s localized in cells of the interstitium and cells at the border between th e gonad and mesonephros. Expression of Renin in the ovary was not detected using standard conditions.