Identification and functional annotation of circular RNA in young and sexually mature boar testicles

We identified 34,521 and 31,803 circRNAs in piglet (30 d) and adult (210 d) boar testis by high-throughput sequencing, respectively. Bioinformatics analysis revealed that these circRNAs are widely distributed on autosomes and sex chromosomes. Some of the host genes can generate multiple circRNAs. A total of 2,326 differentially expressed circRNAs (DECs) derived from 1,526 host genes were found in testicular development, of which 1,003 circRNAs were up-regulated in adult boar testes and 1,323 circRNAs were down-regulated. Furthermore, gene ontology (GO) analysis of host genes of DECs revealed that these circRNAs are mainly involved in regulating spermatogenesis, cilia motility, and hormone biosynthesis. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis revealed that the DECs are markedly enriched to stem cell pluripotency regulation, tight junctions, adhesion junctions, and cAMP signaling pathway. These results indicate that circRNAs are abundantly expressed in boar testes and exhibit dynamic changes during testicular development. Overall design: Identification of circRNA expression profiles in young(3 duplicate samples) and sexually mature(3 duplicate samples) Landrace boar testicles.

本研究通过高通量测序，分别在30日龄仔猪睾丸与210日龄成年公猪睾丸中鉴定出34521条和31803条环状RNA（circRNA）。生物信息学分析显示，这些环状RNA广泛分布于常染色体与性染色体上；部分宿主基因可转录生成多条环状RNA。在公猪睾丸发育进程中，共鉴定到源自1526个宿主基因的2326条差异表达环状RNA（DECs），其中1003条在成年公猪睾丸中表达上调，1323条表达下调。进一步对DECs的宿主基因开展基因本体（gene ontology, GO）分析发现，这些环状RNA主要参与调控精子发生、纤毛运动及激素生物合成过程。京都基因与基因组百科全书（Kyoto Encyclopedia of Genes and Genomes, KEGG）通路富集分析结果显示，DECs显著富集于干细胞多能性调控、紧密连接、黏附连接及cAMP信号通路中。上述结果表明，环状RNA在公猪睾丸中呈高表达状态，并在睾丸发育进程中呈现动态表达变化。实验设计：本研究对青年组（3个生物学重复样本）与性成熟组（3个生物学重复样本）长白公猪睾丸组织的环状RNA表达谱进行鉴定。