Cell-cell communication within the follicle involves many signaling molecules, and this process may be mediated by secretion and uptake of exosomes that contain several bioactive molecules including extra-cellular miRNAs. Follicular fluid and cells from individual follicles of cattle were grouped based on Brilliant Cresyl Blue (BCB) staining of the corresponding oocytes. Both Exoquick precipitation and differential ultracentrifugation were used to separate the exosome and non-exosomal fraction of follicular fluid. Following miRNA isolation from both fractions, the human miRCURY LNA™ Universal RT miRNA PCR array system was used to profile miRNA expression. This analysis found that miRNAs were present in both exosomal and non-exosomal fraction of bovine follicular fluid. We found 25 miRNAs differentially expressed (16 up and 9 down) in exosomes and 30 miRNAs differentially expressed (21 up and 9 down) in non-exosomal fraction of follicular fluid in comparison of BCB- versus BCB+ oocyte groups. Expression of selected miRNAs was detected in theca, granulosa and cumulus oocyte complex. To further explore the potential roles of these follicular fluid derived extra-cellular miRNAs, the potential target genes were predicted, and functional annotation and pathway analysis revealed most of these pathways are known regulators of follicular development and oocyte growth. In order to validate exosome mediated cell-cell communication within follicular microenvironment, we demonstrated uptake of exosomes and resulting increase of endogenous miRNA level and subsequent alteration of mRNA levels in follicular cells in vitro. This study demonstrates for the first time, the presence of exosome or non-exosome mediated transfer of miRNA in the bovine follicular fluid, and oocyte growth dependent variation in extra-cellular miRNA signatures in the follicular environment.

/pdf/exosomal-and-non-exosomal-transport-of-extra-cellular-3l5b38j8p2.pdf

Exosomal and Non-Exosomal Transport of Extra-Cellular microRNAs in Follicular Fluid: Implications for Bovine Oocyte Developmental Competence.

https://www.fertstert.org/article/S0015-0282(14)02064-0/pdf

Molecular characterization of exosomes and their microRNA cargo in human follicular fluid: bioinformatic analysis reveals that exosomal microRNAs control pathways involved in follicular maturation.

Background: Polycystic ovary syndrome (PCOS), the most common endocrinopathy in women of reproductive age, is characterized by polycystic ovaries, chronic anovulation, hyperandrogenism and insulin resistance. Despite the high prevalence of hyperandrogenemia, a definitive endocrine marker for PCOS has so far not been identified. Circulating miRNAs have recently been shown to serve as diagnostic/prognostic biomarkers in patients with cancers. Our current study focused on the altered expression of serum miRNAs and their correlation with PCOS. Method and Results: We systematically used the TaqMan Low Density Array followed by individual quantitative reverse transcription polymerase chain reaction assays to identify and validate the expression of serum miRNAs of PCOS patients. The expression levels of three miRNAs (miR-222, miR-146a and miR-30c) were significantly increased in PCOS patients with respect to the controls in our discovery evaluation and followed validation. The area under the receiver operating characteristic (ROC) curve (AUC) is 0.799, 0.706, and 0.688, respectively. The combination of the three miRNAs using multiple logistic regression analysis showed a larger AUC (0.852) that was more efficient for the diagnosis of PCOS. In addition, logistic binary regression analyses show miR-222 is positively associated with serum insulin, while miR-146a is negatively associated with serum testosterone. Furthermore, bioinformatics analysis indicated that the predicted targets function of the three miRNAs mainly involved in the metastasis, cell cycle, apoptosis and endocrine. Conclusion: Serum miRNAs are differentially expressed between PCOS patients and controls. We identified and validated a class of three serum miRNAs that could act as novel non-invasive biomarkers for diagnosis of PCOS. These miRNAs may be involved in the pathogenesis of PCOS.

/pdf/characterization-of-serum-micrornas-profile-of-pcos-and-1y67ivyb6s.pdf

Characterization of serum microRNAs profile of PCOS and identification of novel non-invasive biomarkers.

https://febs.onlinelibrary.wiley.com/doi/pdf/10.1016/j.febslet.2013.06.023

MicroRNA-133b stimulates ovarian estradiol synthesis by targeting Foxl2

MicroRNAs (miRNAs) are endogenous, small, noncoding single-stranded RNA molecules approximately 22 nucleotides in length. miRNAs are involved in the post-transcriptional regulation of various important cellular physiological and pathological processes, including cell proliferation, differentiation, apoptosis, and hormone biosynthesis and secretion. Ovarian follicles are the key functional units of female reproduction, and the development of these follicles is a complex and precise process accompanied by oocyte maturation as well as surrounding granulosa cell proliferation and differentiation. Numerous miRNAs expressed in the ovary regulate ovarian follicle growth, atresia, ovulation and steroidogenesis and play an important role in ovarian disorders. This review considers recent advances in the identification of miRNAs involved in the regulation of ovarian function as well as the possible influence of miRNAs on ovarian-derived disorders, such as ovarian cancer, polycystic ovarian syndrome and premature ovarian failure. An improved understanding of the regulation of ovarian function by miRNAs may shed light on new strategies for ovarian biology and ovarian disorders.

https://link.springer.com/content/pdf/10.1186%2Fs13048-015-0162-2.pdf

MicroRNAs in ovarian function and disorders.

MicroRNAs (miRNAs) are a class of small non-coding RNAs which function in gene regulation with an important role in cell proliferation, maturation, and activity. The regulatory role of these small RNA molecules has recently begun to be explored in ovarian cells, uncovering their influence on gonadal development, steroidogenesis, apoptosis, ovulation, and corpus luteum development. This emerging area of research has extended and reshaped our understanding on how ovarian function is regulated. Here, we review the current understanding of miRNA biogenesis, the role and mechanism that miRNAs play in post-transcriptional gene expression regulation, and specifically the current evidence of miRNA involvement in ovarian development and function. Future comprehensive understanding of the role of miRNAs in the ovary in both physiological and pathological conditions may offer new treatment strategies for infertility and other ovarian disorders.

/pdf/micrornas-and-ovarian-function-5fgt6yk3ex.pdf

Jason Baley

Papers

MicroRNAs and ovarian function