AUTHOR=Otsuka Kai , Matsubara Shin , Shiraishi Akira , Takei Natsumi , Satoh Yui , Terao Miho , Takada Shuji , Kotani Tomoya , Satake Honoo , Kimura Atsushi P. 

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

JOURNAL=Frontiers in Endocrinology

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/endocrinology/articles/10.3389/fendo.2021.665874

DOI=10.3389/fendo.2021.665874

ISSN=1664-2392

ABSTRACT=<p>The testis expresses many long noncoding RNAs (lncRNAs), but their functions and overview of lncRNA variety are not well understood. The mouse <italic>Prss/Tessp</italic> 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, <italic>Start</italic> (<italic>Steroidogenesis activating lncRNA in testis</italic>), in this locus. <italic>Start</italic> 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. <italic>Start</italic>-knockout (KO) mice generated by the CRISPR/Cas9 system were fertile and showed no morphological abnormality in adults. However, in adult <italic>Start</italic>-KO testes, RNA-seq and qRT-PCR analyses revealed an increase in the expression of steroidogenic genes such as <italic>Star</italic> and <italic>Hsd3b1</italic>, 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 <italic>Start</italic>-KO mice. Since overexpression of <italic>Start</italic> in two Leydig-derived cell lines resulted in elevation of the expression of steroidogenic genes including <italic>Star</italic> and <italic>Hsd3b1</italic>, <italic>Start</italic> is likely to be involved in their upregulation. The increase in expression of steroidogenic genes in adult <italic>Start</italic>-KO testes might be caused by a secondary effect <italic>via</italic> 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 <italic>Start</italic> is a regulator of steroidogenesis in Leydig cells. The current study provides an insight into the overall picture of the function of testis lncRNAs.</p>