CircRNA circ_0043533 facilitates cell growth in polycystic ovary syndrome by targeting miR-1179

Biomarker potential of competing endogenous RNA networks in Polycystic Ovary Syndrome (PCOS)

Polycystic ovary syndrome (PCOS) is the most common condition affecting women of reproductive age globally. PCOS continues to be the largest contributing factor to female infertility despite significant progress in our knowledge of the molecular underpinnings and treatment of the condition. The fact that PCOS is a very diverse condition makes it one of the key reasons why we haven't been able to overcome it. Non-coding RNAs (ncRNAs) are implicated in the development of PCOS, according to growing evidence. However, it is unclear how the complex regulatory relationships between the many ncRNA types contribute to the growth of this malignancy. Competing endogenous RNA (ceRNA), a recently identified mechanism in the RNA world, suggests regulatory interactions between various RNAs, including long non-coding RNAs (lncRNAs), microRNAs (miRNAs), transcribed pseudogenes, and circular RNAs (circRNAs). Recent studies on PCOS have shown that dysregulation of multiple ceRNA networks (ceRNETs) between these ncRNAs plays crucial roles in developing the defining characteristics of PCOS development. And it is believed that such a finding may open a new door for a deeper comprehension of PCOS's unexplored facets. In addition, it may be able to provide fresh biomarkers and effective therapy targets for PCOS. This review will go over the body of information that exists about the primary roles of ceRNETs before highlighting the developing involvement of several newly found ceRNETs in a number of PCOS characteristics.

Role of circular RNA/miRNA axes in the pathophysiology of polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is a disorder resulted from interactions between genetic and environmental factors. Based on the importance of epigenetic factors in the pathoetiology of PCOS, the current review focused on identification of circular RNAs (circRNAs) that are involved in PCOS through acting as molecular sponges for microRNAs (miRNAs). The literature search led to identification of circ_0043533/miR-1179, circ_0030018/miR-136, circ_FURIN/miR-423-5p, circ-FURIN/miR-195-5p, circ_0043532/miR-182, circ_RANBP9/miR-136-5p, circRHBG/miR-515-5p, circMTO1/miR-320b, circASPH/miR-375, circPSMC3/miR-296-3p, circLDLR/miR-1294, circPUM1/miR-760, and hsa_circ_0118530/miR-136 as molecular axes contributing to the pathogenesis of PCOS. To set the stage for future research on the role of the ceRNA network in PCOS, in-silico analyses were performed using miRWalk, miRNet, and miRDIP databases. miRWalk identified 80 genes regulated by 5 miRNAs, miRNet revealed 6449 circRNAs potentially controlling 11 miRNAs, and miRDIP identified 11 miRNAs associated with 35 human pathways. These targets can be used in the treatment options, design of personalized medicine and prediction of prognosis of PCOS.

Berberine Protects Against Dihydrotestosterone-Induced Human Ovarian Granulosa Cell Injury and Ferroptosis by Regulating the Circ_0097636/MiR-186-5p/SIRT3 Pathway

Polycystic ovarian syndrome (PCOS) is an endocrine syndrome in women of reproductive age. Berberine (BBR) is a Chinese herbal monomer that exhibits many pharmacological properties related to PCOS treatment. This study aims to analyze the effect of BBR on a cell model of PCOS and the underlying mechanism. Human ovarian granulosa (KGN) cells were treated with dihydrotestosterone (DHT) to mimic a PCOS cell model. The RNA expression of circ_0097636, miR-186-5p, and sirtuin3 (SIRT3) was determined by quantitative real-time polymerase chain reaction (qRT-PCR). Protein expression was detected by western blotting. Cell viability was analyzed by CCK-8 assay. Cell proliferation and apoptosis were investigated by 5-ethynyl-2'-deoxyuridine (EdU) assay and flow cytometry assay, respectively. The levels of interleukin-6 (IL-6), IL-1β, and tumor necrosis factor-α (TNF-α) were analyzed by enzyme-linked immunosorbent assays (ELISAs). Fe2+ concentration was assessed by an iron assay kit. Oxidative stress was assessed by detecting reactive oxygen species (ROS) level and malondialdehyde (MDA) level using commercial kits. The association of miR-186-5p with circ_0097636 and SIRT3 was identified by dual-luciferase reporter assay and RNA pull-down assay. Circ_0097636 expression was downregulated in the follicular fluid of PCOS patients and DHT-treated KGN cells when compared with control groups. BBR treatment partially relieved the DHT-induced inhibitory effect on cell proliferation and promoted effects on cell apoptosis, inflammation, ferroptosis, and oxidative stress in KGN cells. Additionally, circ_0097636 bound to miR-186-5p, and SIRT3 was identified as a target gene of miR-186-5p in KGN cells. BBR treatment ameliorated DHT-induced KGN cell injury by upregulating circ_0097636 and SIRT3 expression and downregulating miR-186-5p expression. Moreover, circ_0097636 overexpression protected KGN cells from DHT-induced injury by increasing SIRT3 expression. BBR ameliorated DHT-induced KGN cell injury and ferroptosis by regulating the circ_0097636/miR-186-5p/SIRT3 pathway.

Circular RNA as a Novel Regulator and Promising Biomarker in Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is a prevalent metabolic and reproductive disorder that causes low fertility in females. Despite its detrimental effects on women's health, care for PCOS has been impeded by its undefined pathogenesis. Thus, there is an urgent need to explore novel biomarkers and therapeutic targets for the diagnosis and treatment of PCOS. Circular RNAs (circRNAs) are a class of noncoding RNAs with covalently closed cyclic structures, present in high abundance, and show development-stage specific expression patterns. Recent studies have demonstrated that circRNAs participate in PCOS progression by modulating various biological functions, including cell proliferation, apoptosis, and steroidogenesis. In addition, circRNAs are widely present in the follicular fluid of women with PCOS, indicating their potential as diagnostic biomarkers and therapeutic targets for PCOS. This review provides the current knowledge of circRNAs in PCOS, including their regulatory functions and molecular mechanisms, and explores their potential as diagnostic biomarkers and therapeutic targets.

Exosomal circ_0008285 in follicle fluid regulates the lipid metabolism through the miR-4644/ LDLR axis in polycystic ovary syndrome

PURPOSE

Exosomal circRNA, as an essential mediator of the follicular microenvironment, has been implicated in the etiological and pathobiological studies of polycystic ovarian syndrome (PCOS). This study aimed to determine abnormal circular RNA (circRNA) expression profiles in follicle fluid (FF) exosomes in patients with PCOS and identify the role of circ_0008285/microRNA (miR)-4644/low-density lipoprotein receptor (LDLR) axis in PCOS.

METHODS

Sixty-seven women undergoing IVF/ICSI, 31 PCOS patients and 36 non-PCOS patients were included in the cohort study. The circRNA expression profiles of FF exosomes in PCOS (n = 3) and control group (n = 3) were compared by RNA sequencing. In an additional cohort (PCOS:28 vs Control:33), the mRNA expression levels of four circRNAs from FF exosomes were further verified by qRT-PCR. Bioinformatic analysis and dual luciferase reporter gene assay verified the relationship between circ_0008285 and miR-4644 and between miR-4644 and LDLR. KGN cells were infected with sh-circ0008285 and transfected with miR-4644 mimic to verify their roles in lipid metabolism.

RESULTS

Four circRNAs showed significantly different expressions. Circ_0044234 was overexpressed in PCOS patients, while circ_0006877, circ_0013167 and circ0008285 were decreased in PCOS. Among four differentially expressed circRNAs, circ0008285 was enriched in lipoprotein particle receptor activity and cholesterol metabolism pathway by GO and KEGG pathway analyses. Luciferase assay confirmed the competing endogenous RNA (ceRNA) network circ_0008285/miR-4644 /LDLR. The intercellular experiments on circ_0008285 and its reduction in KGN cells showed that the consumption of circ_0008285 in exosomes could increase the expression of miR-4644 in recipient cells and inhibit the expression of LDLR, as well as increase free fatty acid secretion.

CONCLUSION

Circ_0008285 can combine with miR-4644 to promote the expression of LDLR and affect the cholesterol metabolism of ovarian granulosa cells in PCOS. Our findings revealed the ceRNA network of circ_0008285 and provided a new path to investigate lipid metabolism abnormalities in PCOS.

The Role of Circular RNAs in the Physiology and Pathology of the Mammalian Ovary

Circular RNAs (circRNAs) are an abundant class of endogenous non-coding RNAs (ncRNAs) generated from exonic, intronic, or untranslated regions of protein-coding genes or intergenic regions. The diverse, stable, and specific expression patterns of circRNAs and their possible functions through cis/trans regulation and protein-coding mechanisms make circRNA a research hotspot in various biological and pathological processes. It also shows practical value as biomarkers, diagnostic indicators, and therapeutic targets. This review summarized the characteristics, classification, biogenesis and elimination, detection and confirmation, and functions of circRNAs. We focused on research advances circRNAs in the mammalian ovary under conditions including ovarian cancer, polycystic ovarian syndrome (PCOS), and maternal aging, as well as during reproductive status, including ovarian follicle development and atresia. The roles of circRNAs in high reproductive traits in domestic animals were also summarized. Finally, we outlined some obstructive factors and prospects to work with circRNA, aiming to provide insights into the functional research interests of circRNAs in the reproduction and gynecology areas.