Small RNA sequencing reveals distinct nuclear microRNAs in pig granulosa cells during ovarian follicle growth

Derek Toms,Yinshan Bai,Bo Pan,Julang Li

doi:10.1186/s13048-021-00802-3

Derek Toms, Yinshan Bai + Show 2 more

Open Access

https://doi.org/10.1186/s13048-021-00802-3

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Abstract

Nuclear small RNAs have emerged as an important subset of non-coding RNA species that are capable of regulating gene expression. A type of small RNA, microRNA (miRNA) have been shown to regulate development of the ovarian follicle via canonical targeting and translational repression. Little has been done to study these molecules at a subcellular level. Using cell fractionation and high throughput sequencing, we surveyed cytoplasmic and nuclear small RNA found in the granulosa cells of the pig ovarian antral preovulatory follicle. Bioinformatics analysis revealed a diverse network of small RNA that differ in their subcellular distribution and implied function. We identified predicted genomic DNA binding sites for nucleus-enriched miRNAs that may potentially be involved in transcriptional regulation. The small nucleolar RNA (snoRNA) SNORA73, known to be involved in steroid synthesis, was also found to be highly enriched in the cytoplasm, suggesting a role for snoRNA species in ovarian function. Taken together, these data provide an important resource to study the small RNAome in ovarian follicles and how they may impact fertility.

Highlights

Increasing ovarian follicle size has long been an important indicator of oocyte quality, with oocytes obtained from large follicles showing consistently higher in vitro and in vivo developmental potential than their counterparts from small follicles [3, 51]
Six sequences aligned to other RNA species (e.g. Y RNA, Other small RNA species are present in the cytoplasm and nucleus As we had observed significant numbers of reads mapping to small nucleolar RNA (snoRNA) and piRNA (Fig. 2b), we looked further into their subcellular distributions in granulosa cells
This group found that whole-cell expression of miR-181a decreased during follicle development, which is in line with our findings

Summary

Introduction

Increasing ovarian follicle size has long been an important indicator of oocyte quality, with oocytes obtained from large follicles showing consistently higher in vitro and in vivo developmental potential than their counterparts from small follicles [3, 51]. Recent investigations have looked at the distinct populations of small RNA that perform key biological functions in the cytoplasmic and nuclear compartments of cells [19, 41, 47, 60] We present a survey of small RNA species present in gilt granulosa cells obtained from small and large preovulatory follicles, referred to as SGCs and LGCs. While we found a few significant differences between SGCs and LGCs, we did reveal a diverse network of small RNA that showed distinct subcellular localization. While we found a few significant differences between SGCs and LGCs, we did reveal a diverse network of small RNA that showed distinct subcellular localization This small RNAome of ovarian granulosa cells will provide an important resource for studying their subcellular function during follicle growth

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Conclusion