Comparative transcriptome profile analysis of granulosa cells from porcine ovarian follicles during early atresia

Abstract

At various stages of ovarian follicular development, more than 99% of follicles will be eliminated through a degenerative process called atresia. The regulatory mechanisms of atresia have been elucidated to some extent, involving hormones, growth factors, cytokines, and other factors. However, the stimuli initiating atresia in follicular granulosa cells remain unknown. In this study, we isolated the granulosa cells from porcine ovarian follicles (3–5 mm diameter) divided into healthy follicles (HFs) and early atretic follicles (EAFs). We applied high-throughput RNA sequencing to identify and compare differentially expressed genes (DEGs) between HFs and EAFs. A total of 31,694 genes were detected, of which 21,806 were co-expressed in six samples, and 243 genes (p < 0.05; FDR < 0.05) were differentially expressed (DEGs), including 123 downregulated and 120 upregulated in EAFs. GO analysis highlighted hormone metabolism, plasma membrane localization, and transporter activity. The pathway analysis indicated that 51 DEGs, involved in steroidogenesis, cell adhesion molecules, and TGF-beta signaling pathways, were highly related to atresia. Additionally, the interaction network of DEGs (p < 0.01; FDR < 0.05) using STRING highlighted LHR, ACACB, and CXCR4 as central nodes. In summary, this transcriptome analysis enriched our knowledge of the shifted mechanisms in granulosa cells during early atresia and provided novel perspectives into the atresia initiation.

Keywords:

• Follicle atresia
• antral follicles
• RNA sequencing
• granulosa cells
• pig

Authors’ contributions

Conception and design: J.Z. and Z.P.; Manuscript preparation: J.Z. and J.L.; Manuscript revision/review: Z.P. and S.X.; Animal and laboratory experiments: C.W., X.Q., Y. Z., and Y. D.; Interpretation, final approval of the manuscript: Z.P.

Ethics statement

All experiments were conducted according to the guidelines and were approved by the Animal Ethics Committee of Nanjing Agricultural University, Nanjing, Jiangsu, China.

Disclosure statement

We certify no conflict of interest with any financial organization regarding the material discussed in the manuscript. All authors have read and approved the final manuscript.

Additional information

Funding

This study was financially supported by the National Natural Science Foundation of China [Grant Nos. 31902123, 32002175 and 31672421]; the Scientific Research Fund of Jinling Institute of Science and Technology [Grant No. jit-b-202126]; the Key Discipline of Zootechnics of Jinling Institute of Science and Technology and the Jinling Institute of Science and Technology Ecological Breeding Information Technology Innovation Team.