Genome-wide screening differential long non-coding RNAs expression profiles discloses its roles involved in OHSS development

Influence of Long Non-Coding RNAs on Human Oocyte Development

Recent research findings have highlighted the pivotal roles played by lncRNAs in both normal human development and disease pathogenesis. LncRNAs are expressed in oocytes and early embryos, and their expression levels change dynamically once the embryonic genome is activated during early human embryonic development. Abnormal expression of lncRNAs was found in follicular fluid, granulosa cells and oocytes of patients, and these lncRNAs were related to cell proliferation and apoptosis, nuclear maturation and follicle development. The expression levels of some lncRNAs in cumulus cells demonstrate correlations with the quality of oocytes and early embryos. This paper aims to present a comprehensive overview of the influence of LncRNAs on the developmental process of human oocytes as well as their involvement in certain infertility-related diseases.

lncRNA-FMR6 directly binds SAV1 to increase apoptosis of granulosa cells in premature ovarian failure

BACKGROUND

A regulatory mechanism of lncRNA binding to protein has been detected in premature ovarian failure (POF). Therefore, this study was expected to illustrate the mechanism of lncRNA-FMR6 and SAV1 regulating POF.

METHODS

Follicular fluid and ovarian granulosa cells (OGCs) from POF patients and healthy volunteers were collected. Using RT-qPCR and western blotting, lncRNA-FMR6 and SAV1 expression were detected. KGN cells were cultured, and the subcellular localization analysis of lncRNA-FMR6 was carried out. In addition, KGN cells were treated with lncRNA-FMR6 knockdown/overexpression or SAV1 knockdown. Then, cell optical density (proliferation), apoptosis rate, Bax and Bcl-2 mRNA expression were explored by CCK-8, caspase-3 activity, flow cytometry and RT-qPCR analysis. By performing RIP and RNA pull-down experiments, the interactions among lncRNA-FMR6 and SAV1 was investigated.

RESULTS

Up-regulation of lncRNA-FMR6 was shown in follicular fluid and OGCs of POF patients, and ectopic overexpression of lncRNA-FMR6 promoted KGN cells apoptosis and inhibited proliferation. lncRNA-FMR6 was localized in the cytoplasm of KGN cells. SAV1 bounding to lncRNA-FMR6 was negatively regulated by lncRNA-FMR6, and was down-regulated in POF. SAV1 knockdown promoted KGN cells proliferation and inhibited apoptosis, and partially eliminated the effect of lncRNA-FMR6 low expression on KGN cells.

CONCLUSION

Overall, lncRNA-FMR6 accelerates POF progression by binding to SAV1.

Exosomal miR-27 negatively regulates ROS production and promotes granulosa cells apoptosis by targeting SPRY2 in OHSS

Ovarian hyperstimulation syndrome (OHSS) is one of the most dangerous iatrogenic complications in controlled ovarian hyperstimulation (COH). The exact molecular mechanism that induces OHSS remains unclear. In recent years, accumulating evidence found that exosomal miRNAs participate in many diseases of reproductive system. However, the specific role of miRNAs, particularly the follicular fluid-derived exosomal miRNAs in OHSS remains controversial. To identify differentially expressed follicular fluid exosomal miRNAs from OHSS and non-OHSS patients, the analysis based on miRNA-sequence was conducted. The levels of 291 miRNAs were significantly differed in exosomes from OHSS patients compared with normal control, and exosomal miR-27 was one of the most significantly down-regulated miRNAs in the OHSS group. By using MiR-27 mimic, we found it could increase ROS stress and apoptosis by down-regulating the expression of p-ERK/Nrf2 pathway by negatively regulating SPRY2. These data demonstrate that exosomal miRNAs are differentially expressed in follicular fluid between patients with and without OHSS, and follicular fluid exosomal miR-27 may involve in the pathological process of OHSS development.

Long noncoding RNA HCP5 participates in premature ovarian insufficiency by transcriptionally regulating MSH5 and DNA damage repair via YB1

The genetic etiology of premature ovarian insufficiency (POI) has been well established to date, however, the role of long noncoding RNAs (lncRNAs) in POI is largely unknown. In this study, we identified a down-expressed lncRNA HCP5 in granulosa cells (GCs) from biochemical POI (bPOI) patients, which impaired DNA damage repair and promoted apoptosis of GCs. Mechanistically, we discovered that HCP5 stabilized the interaction between YB1 and its partner ILF2, which could mediate YB1 transferring into the nucleus of GCs. HCP5 silencing affected the localization of YB1 into nucleus and reduced the binding of YB1 to the promoter of MSH5 gene, thereby diminishing MSH5 expression. Taken together, we identified that the decreased expression of HCP5 in bPOI contributed to dysfunctional GCs by regulating MSH5 transcription and DNA damage repair via the interaction with YB1, providing a novel epigenetic mechanism for POI pathogenesis.

Long non-coding RNAs in ovarian granulosa cells

Granulosa cells (GCs) are somatic cells surrounding oocytes within follicles and are essential for folliculogenesis. Pathological changes in GCs are found in several ovarian disorders. Recent reports have indicated that long non-coding RNAs (lncRNAs), which modulate gene expression via multiple mechanisms, are key regulators of the normal development of GCs, follicles, and ovaries. In addition, accumulating evidence has suggested that lncRNAs can be utilized as biomarkers for the diagnosis and prognosis of GC-related diseases, such as polycystic ovary syndrome (PCOS) and premature ovarian insufficiency (POI). Therefore, lncRNAs not only play a role in GCs that are involved in normal folliculogenesis, but they may also be considered as potential candidate biomarkers and therapeutic targets in GCs under pathological conditions. In the future, a detailed investigation of the in vivo delivery or targeting of lncRNAs and large-cohort-validation of the clinical applicability of lncRNAs is required.