College of Animal Science and Technology, Nanjing Agriculture University, Nanjing, Jiangsu, P. R. China 210095.
College of Animal Science and Technology, Nanjing Agriculture University, Nanjing, Jiangsu, P. R. China 210095; National Experimental Teaching Demonstration Center of Animal Science, Nanjing Agriculture University, Nanjing, Jiangsu, P. R. China 210095.
Domest Anim Endocrinol. 2020 Jul;72:106401. doi: 10.1016/j.domaniend.2019.106401. Epub 2019 Oct 5.
The specific expression profile and function of circular RNAs (circRNAs) in mammalian ovarian follicles, especially during the atresia process, are unclear. In this study, genome-wide deep circRNA sequencing was applied to screen circRNAs in healthy and early atretic antral follicles in pig ovaries. A total of 40,567 distinct circRNAs were identified in follicles, among which 197 circRNAs (108 upregulated and 89 downregulated) were significantly shifted during the early atresia process. Most differentially expressed circRNAs (DECs) lacked protein-coding potential. Annotation analysis of the DECs revealed 162 known host genes, or noncoding RNAs, and 10 intergenic regions. The key pathways in which these host genes are involved include the focal adhesion-PI3K-Akt-mTOR signaling pathway, vascular endothelial growth factor A (VEGFA)-vascular endothelial growth factor receptor 2 signaling pathway and transforming growth factor-beta signaling pathway. Further comparison analysis between host genes of DECs and the differentially expressed linear messenger RNA transcripts revealed the cotranscription of circRNAs and their linear mRNAs in inhibin beta units (INHBA and INHBB), glutathione S-transferase (GSTA1), and VEGFA. In addition, we predicted 196 pairs of potential circRNA-micro RNA (miRNA) interactions among 77 DECs and 101 porcine miRNAs. We have identified 16 functional miRNAs by comparing the 101 miRNAs to the functional miRNAs reported in mammal ovarian follicle atresia and granulosa cell apoptosis studies. Our study adds new knowledge to circRNA distribution profiles in pig ovarian follicles, offers a valuable reference for transcriptomic profiles in the initiation of follicular atresia, highlights warranted circRNAs for further functional investigation, and provides possible biomarkers for ovarian dysfunctions.
哺乳动物卵巢卵泡中环状 RNA（circRNA）的特异性表达谱和功能尚不清楚，尤其是在闭锁过程中。本研究应用全基因组深度 circRNA 测序筛选猪卵巢中健康和早期闭锁腔前卵泡中的 circRNA。在卵泡中鉴定出 40567 个独特的 circRNA，其中 197 个 circRNA（108 个上调，89 个下调）在早期闭锁过程中明显变化。大多数差异表达的 circRNA（DECs）缺乏编码蛋白的潜力。对 DECs 的注释分析显示，有 162 个已知的宿主基因或非编码 RNA，以及 10 个基因间区。这些宿主基因参与的关键途径包括焦点黏附-PI3K-Akt-mTOR 信号通路、血管内皮生长因子 A（VEGFA）-血管内皮生长因子受体 2 信号通路和转化生长因子-β信号通路。在 DECs 的宿主基因和差异表达的线性信使 RNA 转录本之间进一步比较分析显示，circRNA 及其线性 mRNA 在抑制素β亚单位（INHBA 和 INHBB）、谷胱甘肽 S-转移酶（GSTA1）和 VEGFA 中共同转录。此外，我们在 77 个 DECs 和 101 个猪 miRNA 之间预测了 196 对潜在的 circRNA-miRNA（miRNA）相互作用。通过将 101 个 miRNA 与哺乳动物卵巢卵泡闭锁和颗粒细胞凋亡研究中报道的功能性 miRNA 进行比较，我们鉴定出了 16 个功能性 miRNA。本研究为猪卵巢卵泡中 circRNA 的分布谱提供了新的知识，为卵泡闭锁起始的转录组谱提供了有价值的参考，突出了值得进一步功能研究的 circRNA，并为卵巢功能障碍提供了可能的生物标志物。
