1700108J01Rik and 1700101O22Rik are mouse testis-specific long non-coding RNAs

Long non-coding RNAs (lncRNAs; > 200 nucleotides in length) have attracted attention as fine-tuners of gene expression. However, little is known about the cell- and stage-specific expression pattern and function of lncRNAs in spermatogenesis. The purpose of this study was to identify mouse testis-associated lncRNAs using a combination of computational and experimental approaches. We first used the FANTOM5 database to survey lncRNA expression in the mouse testis and performed reverse transcription quantitative polymerase chain reaction (real-time PCR) and in situ hybridization (ISH) analyses. In silico analysis showed that most of the highly expressed lncRNAs in the adult mouse testis were testis-specific lncRNAs and were expressed at and following the initiation of spermatogenesis. We selected the antisense lncRNA 1700108J01Rik and long intergenic non-coding RNA 1700101O22Rik from the most highly expressed lncRNAs in the adult testis for further analysis. Real-time PCR analysis confirmed that 1700108J01Rik and 1700101O22Rik were specifically expressed in the testis. ISH analysis revealed that the two mouse-testis-specific lncRNAs were expressed exclusively in testicular germ cells in meiotic prophase and the round spermatid stage, which coincide with the period of transcriptional reactivation during spermatogenesis. The cytoplasmic distribution of these lncRNAs revealed by ISH suggests their involvement in post-transcriptional gene regulation rather than in epigenetic or transcriptional regulation. Our data provide new insight into testis-associated lncRNAs that will be useful in expression and functional studies of spermatogenesis.