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Topaz1 is a gene initially discovered in the fetal ovaries of ewes during meiosis. It is well conserved in vertebrates and its expression is specific of germ cells. A murine model lacking the gene Topaz1 (KO), was generated. This allowed to identify its role in male fertility. The absence of this gene leads to meiotic arrest after prophase I and a chromosome misalignment at the metaphase I plate.

In order to better characterize the tecticule phenotype of Topaz 1-/- mice, high-throughput transcriptomic analyses were done by RNA sequencing. The absence of TOPAZ1 disturbs the expression of genes implicated in the mobility of microtubules and/or the cilium, biological processes necessary for spermatogenesis. In addition, one quarter of the dysregulated genes are lncRNA specific for male germ cells of which some are not expressed in Topaz1 -/- testicules. A mouse line in which the expression of one of these lncRNA (4939463O16Rik) was suppressed showed that fertility in these mice is not affected. Yet certain sperm parameters are modified and the concentration of sperm decreased by half in these animals.

This work identifies a lncRNA (4930463O16Rik) whose expression is dependent on Topaz1 and that is the key element, for both the production and motility of sperm.