Dynamic transcriptome analysis of Maiwa yak corpus luteum during the estrous cycle

Maiwa yak is a special breed of animal living on the Qinghai-Tibet Plateau, which has great economic value, but its fertility rate is low. The corpus luteum (CL) is a temporary tissue that plays a crucial role in maintaining the physiological cycle. However, little is known about the transcriptome profile in Maiwa yak CL. In the present study, the transcriptome of Maiwa yak CL at early (EYCL), middle (MYCL) and late-stages (LYCL) was studied employing high-throughput sequencing. A total of 25,922 transcripts were identified, including 22,277 known as well as 3,645 novel ones. Furthermore, 690 and 212 differentially expressed (DE) mRNAs were detected in the EYCL vs. MYCL and MYCL vs. LYCL groups, respectively. KEGG pathway enrichment analysis of DEGs illustrated that the most enriched pathway was PI3K-Akt pathway. Furthermore, twenty-six DEGs were totally found to be associated with different biological processes of CL development. One of these genes, PGRMC1, displayed a dynamical expression trend during the lifespan of yak CL. The knockdown of PGRMC1 in luteinized yak granulosa cells resulted in defective steroidogenesis. In conclusion, this study analyzed the transcriptome profiles in yak CL of different stages, and provided a novel database for analyzing the gene network in yak CL.HIGHLIGHTSThe manuscript analyzed the transcriptome profiles in yak CL during the estrous cycle.Twenty-six DEGs were found to be associated with the development or function of CL.One of the DEGs, PGRMC1, was found to be responsible for steroidogenesis in luteinized yak granulosa cells. The manuscript analyzed the transcriptome profiles in yak CL during the estrous cycle. Twenty-six DEGs were found to be associated with the development or function of CL. One of the DEGs, PGRMC1, was found to be responsible for steroidogenesis in luteinized yak granulosa cells.

麦洼牦牛（Maiwa yak）是栖息于青藏高原的特有畜禽品种，具备极高经济价值，但繁殖率偏低。黄体（corpus luteum, CL）是维持动物生理周期的关键临时性组织，目前学界对麦洼牦牛黄体的转录组特征仍知之甚少。本研究采用高通量测序技术，对麦洼牦牛早期（early-stage CL, EYCL）、中期（middle-stage CL, MYCL）与晚期（late-stage CL, LYCL）黄体的转录组进行了分析。研究共鉴定得到25922条转录本，其中22277条为已知转录本，3645条为新预测转录本。此外，在EYCL与MYCL的对比组、MYCL与LYCL的对比组中，分别检测到690个和212个差异表达（differentially expressed, DE）mRNA。对差异表达基因（differentially expressed genes, DEGs）的KEGG通路富集分析结果显示，富集程度最高的通路为PI3K-Akt通路。进一步筛选发现，共计26个差异表达基因与黄体发育的不同生物学过程密切相关。其中，PGRMC1在牦牛黄体的整个生命周期中呈现动态表达趋势。在黄体化牦牛颗粒细胞中敲低PGRMC1会导致类固醇生成功能异常。综上，本研究解析了不同发育阶段麦洼牦牛黄体的转录组谱，为解析牦牛黄体的基因调控网络提供了全新的研究数据库。

研究亮点：
1. 本研究解析了发情周期内牦牛黄体的转录组特征；
2. 共鉴定出26个与黄体发育及功能相关的差异表达基因；
3. 差异表达基因PGRMC1可调控黄体化牦牛颗粒细胞的类固醇生成过程。