A Testis-Specific Long Noncoding RNA, , Is a Regulator of Steroidogenesis in Mouse Leydig Cells.

The testis expresses many long noncoding RNAs (lncRNAs), but their functions and overview of lncRNA variety are not well understood. The mouse locus contains six serine protease genes and two lncRNAs that have been suggested to play important roles in spermatogenesis. Here, we found a novel testis-specific lncRNA, (), in this locus. is 1822 nucleotides in length and was found to be localized mostly in the cytosol of germ cells and Leydig cells, although nuclear localization was also observed. -knockout (KO) mice generated by the CRISPR/Cas9 system were fertile and showed no morphological abnormality in adults. However, in adult -KO testes, RNA-seq and qRT-PCR analyses revealed an increase in the expression of steroidogenic genes such as and , while ELISA analysis revealed that the testosterone levels in serum and testis were significantly low. Interestingly, at 8 days postpartum, both steroidogenic gene expression and testosterone level were decreased in -KO mice. Since overexpression of in two Leydig-derived cell lines resulted in elevation of the expression of steroidogenic genes including and , is likely to be involved in their upregulation. The increase in expression of steroidogenic genes in adult -KO testes might be caused by a secondary effect the androgen receptor autocrine pathway or the hypothalamus-pituitary-gonadal axis. Additionally, we observed a reduced number of Leydig cells at 8 days postpartum. Collectively, our results strongly suggest that is a regulator of steroidogenesis in Leydig cells. The current study provides an insight into the overall picture of the function of testis lncRNAs.