N6-methyladenosine Demethylase FTO Induces the Dysfunctions of Ovarian Granulosa Cells by Upregulating Flotillin 2

Fat mass and obesity-associated protein (FTO)-induced upregulation of flotillin-2 (FLOT2) contributes to cancer aggressiveness in diffuse large B-cell lymphoma (DLBCL) via activating the PI3K/Akt/mTOR signal pathway

The role of fat mass and obesity-associated protein (FTO)-mediated N6-methyladenosine (m6A)-demethylation has been investigated in various types of cancers, but it is still unclear whether FTO participates in the progression of diffuse large B-cell lymphoma (DLBCL). Here, by conducting Real-Time qPCR and Western Blot analysis, we verified that FTO was especially enriched in the DLBCL cells (RCK-8, LY-3, DHL-6 and U2932) compared to normal WIL2S cells. Then, the overexpression and silencing vectors for FTO were delivered into the LY-3 and U2932 cells, and our functional experiments confirmed that silencing of FTO suppressed cell viability and division, and induced apoptotic cell death in the DLBCL cells, whereas FTO-overexpression exerted opposite effects. Further mechanical experiments showed that FTO demethylated m6A modifications in flotillin-2 (FLOT2) mRNA to sustain its stability for FLOT2 upregulation, and elevated FLOT2 subsequently increased the expression levels of phosphorylated PI3K (p-PI3K), p-Akt and p-mTOR to activate the tumor-initiating PI3K/Akt/mTOR signal pathway. Of note, FLOT2 also serve as an oncogene to enhance cancer malignancy in DLBCL, and the rescuing experiments showed that FTO-ablation induced suppressing effects on the malignant phenotypes in DLBCL were all abrogated by overexpressing FLOT2. Taken together, those data hinted that FTO-mediated m6A-demethylation upregulated FLOT2 to activate the downstream PI3K/Akt/mTOR signal pathway, leading to the aggressiveness of DLBCL, which potentially provided diagnostic, therapeutic and prognostic biomarkers for DLBCL.

FTO demethylates regulates cell-cycle progression by controlling CCND1 expression in luteinizing goat granulosa cells

In mammals, N6-methyladenosine (m6A) stands out as one of the most abundant internal mRNA modifications and plays a crucial role in follicular development. Nonetheless, the precise mechanism by which the demethylase FTO regulates the progression of the goat luteinizing granulosa cells (LGCs) cycle remains to be elucidated. In our study, we primarily assessed the protein and mRNA expression levels of genes using Western blotting and quantitative real-time polymerase chain reaction (qRT-PCR), cell proliferation via EdU, cell viability with CCK-8, and apoptosis and cell cycle progression through flow cytometry. Here, the results demonstrated that knockdown of FTO significantly enhanced apoptosis, impeded cell proliferation, and increased autophagy levels in goat LGCs. Furthermore, the silencing of FTO substantially reduced cyclin D1 (CCND1) expression through the recognition and degradation of YTHDF2, consequently prolonging the cell cycle progression. This study sheds light on the mechanism by which FTO demethylation governs cell cycle progression by controlling the expression of CCND1 in goat LGCs, underscoring the dynamic role of m6A modification in the regulation of cell cycle progression.

YTHDF2 as a Mediator in BDNF-Induced Proliferation of Porcine Follicular Granulosa Cells

In female mammals, the proliferation and apoptosis of granulosa cells (GCs) are critical in determining the fate of follicles and are influenced by various factors, including brain-derived neurotrophic factor (BDNF). Previous research has shown that BDNF primarily regulates GC proliferation through the PI3K/AKT, NF-kB, and CREB tumour pathways; however, the role of other molecular mechanisms in mediating BDNF-induced GC proliferation remains unclear. In this study, we investigated the involvement of the m6A reader YTH domain-containing family member 2 (YTHDF2) in BDNF-stimulated GC proliferation and its underlying mechanism. GCs were cultured in DMEM medium supplemented with varying BDNF concentrations (0, 10, 30, 75, and 150 ng/mL) for 24 h. The viability, number, and cell cycle of GCs were assessed using the CCK-8 assay, cell counting, and flow cytometry, respectively. Further exploration into YTHDF2's role in BDNF-stimulated GC proliferation was conducted using RT-qPCR, Western blotting, and sequencing. Our findings indicate that YTHDF2 mediates the effect of BDNF on GC proliferation. Additionally, this study suggests for the first time that BDNF promotes YTHDF2 expression by increasing the phosphorylation level of the ERK1/2 signalling pathway. This study offers a new perspective and foundation for further elucidating the mechanism by which BDNF regulates GC proliferation.

FTO: a critical role in obesity and obesity-related diseases

In recent years, obesity is a growing pandemic in the world and has likely contributed to increasing the incidence of obesity-related diseases. Fat mass and obesity-associated gene (FTO) is the first gene discovered which has a close connection with fat. Recent studies suggested that FTO gene has played an important role in the molecular mechanisms of many diseases. Obesity is considered to be a hereditary disease and can evoke many kinds of diseases, including polycystic ovary syndrome (PCOS), type 2 diabetes mellitus (T2DM), cancer, etc., whose exact possible molecular mechanisms responsible for the effect of FTO on obesity and obesity-related diseases remain largely unknown. In this review, we comprehensively discuss the correlation between FTO gene and obesity, cancer, PCOS, T2DM, as well as the molecular mechanism involved in these diseases.

N6-methyladenosine demethylase FTO related to hyperandrogenism in PCOS via AKT pathway

BACKGROUND

Polycystic ovary syndrome (PCOS) was known as the common endocrine disease in women, featured as hyperandrogenism, ovulation disorders, etc. Fat mass and obesity-associated protein (FTO), a m6A demethylase, is abnormal in the occurrence of ovarian diseases. However, the mechanism of FTO in the pathogenesis of PCOS is still unclear.

METHODS

The level of FTO in clinical samples, PCOS rat with hyperandrogenism and granulosa cells (GCs) lines effected by DHT were investigated by ELISA, qRT-PCR, WB, and IHC, while m6A RNA methylation level was studied by m6A Colorimetric and androgen level was tested through ELISA. Changes in steroid hormone synthetase and androgen receptor (AR)/prostate-specific antigen (PSA) levels in vitro were visualized by WB after transient transfection silenced FTO. The effect of DHT combined with FTO inhibitor meclofenamic acid (MA) on FTO, AR/PSA, and AKT phosphorylation were also demonstrated by WB. The co-localization of FTO and AR in KGN cells was analyzed by confocal microscopy, and the physiological interaction between FTO and AR was studied by Co-IP assay. The effect of FTO-specific inhibitor MA, AKT phosphorylation inhibitor LY294002, and the combined them on GCs proliferation and cell cycle were evaluated by drug combination index, EDU assay, and flow cytometry analysis.

RESULTS

FTO expression was upregulated in follicular fluid and GCs in PCOS patients clinically. The high FTO expression in patients was negative with the level of m6A, but positive with the level of androgen. The upregulation of FTO was accompanied with a decrease in the level of m6A in PCOS rat with hyperandrogenism. Dihydrotestosterone (DHT) promoted the FTO expression and inhibited m6A content as a dose-dependent way in vitro. In contrast, suppression of FTO with siRNA attenuated the expression of steroid hormone synthetase such as CYP11A1, CYP17A1, HSD11B1, HSD3B2 except CYP19A1 synthetase, ultimately inducing the decrease of androgen level. Suppression of FTO also decreased the biological activity of androgen through downregulation AR/PSA. MA treatment as the specific FTO antagonist decreased cell survival in time- and dose-dependent way in GCs lines. Correspondingly, MA treatment decreased the expression of FTO, AR/PSA expression, and AKT phosphorylation in the presence of DHT stimulation. Additionally, we also speculate there is a potential relation between FTO and AR according to FTO was co-localized and interacted with AR in KGN cells. Compared with AKT phosphorylation inhibitor LY294002 or MA alone, LY294002 combined with MA synergistically inhibited cell survival and increased G2/M phase arrest in GC line.

CONCLUSIONS

We first evaluated the correlation of FTO and m6A in PCOS clinically, and further explored the mechanism between FTO and hyperandrogenism in PCOS animal and cell models. These findings contributed the potential therapy by targeting the FTO for hyperandrogenism in PCOS.

FLOT1, stabilized by WTAP/IGF2BP2 mediated N6-methyladenosine modification, predicts poor prognosis and promotes growth and invasion in gliomas

The expression, function, and mechanism of FLOT1 (flotillin-1) remains unknown in gliomas. Here, the expression and clinical value of FLOT1 in gliomas was bioinformatically and experimentally analyzed via online omics data and local tissues. Moreover, the effects of FLOT1 depletion on cell proliferation and invasion were also detected. Besides, the underlying roles of N6-methyladenosine modification (m6A) in FLOT1 upregulation was further explored. The results demonstrated that FLOT1 was significantly upregulated in gliomas and positively correlated with advanced progression and poor prognosis of patients. FLOT1 silencing notably suppressed the cell proliferation and invasion in gliomas. The expression of WTAP and IGF2BP2was positively correlated with FLOT1 expression and served as the writer and reader of FLOT1 m6A, respectively, which stabilized FLOT1 mRNA and maintained its upregulation in gliomas. Lastly, ectopic expression of FLOT1 could notably restore the inhibitory effects caused by WTAP and IGF2BP2 depletion in glioma cells. Collectively, our results originally confirmed the upregulation and oncogenic roles of FLOT1, and revealed that WTAP/IGF2BP2 mediated m6A contributed to the upregulation of FLOT1 in gliomas, highlighting the promising application of WTAP/IGF2BP2/FLOT1 axis in target treatment of gliomas.

Multi-omics insights and therapeutic implications in polycystic ovary syndrome: a review

Polycystic ovary syndrome (PCOS) is a common gynecological disease that causes adverse effects in women in their reproductive phase. Nonetheless, the molecular mechanisms remain unclear. Over the last decade, sequencing and omics approaches have advanced at an increased pace. Omics initiatives have come to the forefront of biomedical research by presenting the significance of biological functions and processes. Thus, multi-omics profiling has yielded important insights into understanding the biology of PCOS by identifying potential biomarkers and therapeutic targets. Multi-omics platforms provide high-throughput data to leverage the molecular mechanisms and pathways involving genetic alteration, epigenetic regulation, transcriptional regulation, protein interaction, and metabolic alterations in PCOS. The purpose of this review is to outline the prospects of multi-omics technologies in PCOS research by revealing novel biomarkers and therapeutic targets. Finally, we address the knowledge gaps and emerging treatment strategies for the management of PCOS. Future PCOS research in multi-omics at the single-cell level may enhance diagnostic and treatment options.

METTL3-mediated m6A methylation regulates granulosa cells autophagy during follicular atresia in pig ovaries

Follicular atresia is a normal physiological event in mammals, yet its mechanism remains to be studied. Granulosa cell (GC) autophagy is closely associated with follicular atresia. The N6-methyladenosine (m6A) modification is the most common post-transcriptional modification in eukaryotes, but its role in follicular atresia is still unknown. In this study, the possible relationship amongst follicular atresia, GC autophagy and m6A modification was studied. Our results showed that the level of autophagy in GCs increased with the degree of follicle atresia, whereas the overall m6A level decreased. Rapamycin treatment induced atresia in vitro cultured follicles, whereas 3-Methyladenine inhibited follicular atresia. Progressed atretic follicle (PAF) GCs had significantly lower METTL3 levels and significantly higher FTO levels than healthy follicle (HF) GCs. Differential gene expression analysis of GCs in PAF and HF by RNA sequencing was showed that the autophagy-related genes ULK1, ULK2, ATG2A, and ATG2B were significantly elevated in the PAF. In cultured GCs, overexpression of METTL3 significantly decreased the mRNA level of ULK1, as well as the autophagy level, whereas knockdown of METTL3 by RNAi significantly increased the mRNA level of ULK1, as well as the autophagy level. Our results indicate that m6A modification can regulate autophagy in GCs and play a role in the process of porcine follicular atresia.

N6-methyladenosine regulator-mediated methylation modification patterns and immune infiltration characterization in Polycystic Ovary Syndrome (PCOS)

BACKGROUND

Polycystic ovary syndrome (PCOS) is a multisystem-related disease whose pathophysiology is still unclear. Several regulators of N6-methyladenosine (m6A) modification were confirmed to play a regulatory role in PCOS. Nonetheless, the roles of m6A regulators in PCOS are not fully demonstrated.

MATERIALS AND METHODS

Four mRNA expression profiling microarrays were obtained from the Gene Expression Omnibus (GEO) database. Differentially expressed m6A regulators between PCOS and normal patients were identified by R software. A random forest modal and nomogram were developed to assess the relationship between m6A regulators and the occurrence risk of PCOS. A consensus clustering method was utilized to distinctly divide PCOS patients into two m6A subtypes (m6A cluster A/B). The patterns of differential expression and immune infiltration were explored between the two m6A clusters.

RESULTS

In this study, 22 significant m6A regulators were identified between healthy controls and PCOS patients. The random forest model determined three optimal m6A regulators which are related to the occurrence risk of PCOS, including YTHDF1, RBM15 and METTL14. A nomogram was established based on these genes, and its predictive reliability was validated by decision curve analysis. The consensus clustering algorithm distinctly divided PCOS cases into two m6A subtypes. The ssGSEA algorithm found that the immune infiltration was markedly enriched in m6A cluster B than in cluster A. The m6A-pattern related differentially expressed genes (DEGs) of the two m6A subtypes were demonstrated by differential expression analysis. We found that they were enriched in immune-related genes and various infection pathways. Based on the m6A-pattern related DEGs, the PCOS patients were classified into two m6A-pattern related genomic subtypes (gene clusters A and B).

CONCLUSIONS

The present study provided evidence concerning the different modification patterns of m6A regulators in PCOS compared with normal patients. This study will help clarify the overall impact of m6A modification patterns and related immune infiltration on PCOS.

RNA N6-methyladenosine modification in female reproductive biology and pathophysiology

Gene expression and posttranscriptional regulation can be strongly influenced by epigenetic modifications. N⁶-methyladenosine, the most extensive RNA modification, has been revealed to participate in many human diseases. Recently, the role of RNA epigenetic modifications in the pathophysiological mechanism of female reproductive diseases has been intensively studied. RNA m⁶A modification is involved in oogenesis, embryonic growth, and foetal development, as well as preeclampsia, miscarriage, endometriosis and adenomyosis, polycystic ovary syndrome, premature ovarian failure, and common gynaecological tumours such as cervical cancer, endometrial cancer, and ovarian cancer. In this review, we provide a summary of the research results of m⁶A on the female reproductive biology and pathophysiology in recent years and aim to discuss future research directions and clinical applications of m⁶A-related targets. Hopefully, this review will add to our understanding of the cellular mechanisms, diagnostic biomarkers, and underlying therapeutic strategies of female reproductive system diseases. Video Abstract.

Identifying novel genetic loci associated with polycystic ovary syndrome based on its shared genetic architecture with type 2 diabetes

Genome-wide association studies (GWAS) have identified several common variants associated with polycystic ovary syndrome (PCOS). However, the etiology behind PCOS remains incomplete. Available evidence suggests a potential genetic correlation between PCOS and type 2 diabetes (T2D). The publicly available data may provide an opportunity to enhance the understanding of the PCOS etiology. Here, we quantified the polygenic overlap between PCOS and T2D using summary statistics of PCOS and T2D and then identified the novel genetic variants associated with PCOS behind this phenotypic association. A bivariate causal mixture model (MiXeR model) found a moderate genetic overlap between PCOS and T2D (Dice coefficient = 44.1% and after adjusting for body mass index, 32.1%). The conditional/conjunctional false discovery rate method identified 11 potential risk variants of PCOS conditional on associations with T2D, 9 of which were novel and 6 of which were jointly associated with two phenotypes. The functional annotation of these genetic variants supports a significant role for genes involved in lipid metabolism, immune response, and the insulin signaling pathway. An expression quantitative trait locus functionality analysis successfully repeated that 5 loci were significantly associated with the expression of candidate genes in many tissues, including the whole blood, subcutaneous adipose, adrenal gland, and cerebellum. We found that SCN2A gene is co-localized with PCOS in subcutaneous adipose using GWAS-eQTL co-localization analyses. A total of 11 candidate genes were differentially expressed in multiple tissues of the PCOS samples. These findings provide a new understanding of the shared genetic architecture between PCOS and T2D and the underlying molecular genetic mechanism of PCOS.

The Role of m6A on Female Reproduction and Fertility: From Gonad Development to Ovarian Aging

The growth and maturation of oocyte is accompanied by the accumulation of abundant RNAs and posttranscriptional regulation. N6-methyladenosine (m⁶A) is the most prevalent epigenetic modification in mRNA, and precisely regulates the RNA metabolism as well as gene expression in diverse physiological processes. Recent studies showed that m⁶A modification and regulators were essential for the process of ovarian development and its aberrant manifestation could result in ovarian aging. Moreover, the specific deficiency of m⁶A regulators caused oocyte maturation disorder and female infertility with defective meiotic initiation, subsequently the oocyte failed to undergo germinal vesicle breakdown and consequently lost the ability to resume meiosis by disrupting spindle organization as well as chromosome alignment. Accumulating evidence showed that dysregulated m⁶A modification contributed to ovarian diseases including polycystic ovarian syndrome (PCOS), primary ovarian insufficiency (POI), ovarian aging and other ovarian function disorders. However, the complex and subtle mechanism of m⁶A modification involved in female reproduction and fertility is still unknown. In this review, we have summarized the current findings of the RNA m⁶A modification and its regulators in ovarian life cycle and female ovarian diseases. And we also discussed the role and potential clinical application of the RNA m⁶A modification in promoting oocyte maturation and delaying the reproduction aging.

FTO Alleviates CdCl2-Induced Apoptosis and Oxidative Stress via the AKT/Nrf2 Pathway in Bovine Granulosa Cells

Cadmium (Cd) is a common environmental heavy metal contaminant of reproduction toxicity. Cd accumulation in animals leads to the damage of granulosa cells. However, its mechanism needs to be elucidated. This research found that treating granulosa cells with Cd resulted in reduced cell viability. The flow cytometry results showed that Cd increased the degree of apoptosis and level of superoxide anion (O₂^-) in granulosa cells. Further analysis showed that Cd treatment resulted in reduced expression levels of nuclear factor erythroid 2-related factor-2 (Nrf2), superoxide dismutase (SOD), catalase (CAT) and NAD(P)H: quinone oxidoreductase 1 (NQO1), and an increased expression level of malondialdehyde (MDA); the expression levels of Bcl-2 associated X (Bax) and caspase-3 increased, whereas that of B-cell lymphoma 2 (Bcl-2) decreased. Changes in m⁶A methylation-related enzymes were noted with Cd-induced damage to granulosa cells. The results of transcriptome and MeRIP sequencing revealed that the AKT pathway participated in Cd-induced damage in granulosa cells, and the MAX network transcriptional repressor (MNT) may be a potential target gene of fat mass and obesity-associated protein (FTO). FTO and YTH domain family member 2 (YTHDF2) regulated MNT expression through m⁶A modification. FTO overexpression alleviated Cd-induced apoptosis and oxidative stress through the activation of the AKT/Nrf2 pathway; this process could be reversed using siMNT. Overall, these findings associated m⁶A with Cd-induced damage to granulosa cells and provided insights into Cd-induced granulosa cell cytotoxicity from a new perspective centered on m⁶A modification.

N6-Methyladenosine Modifications in the Female Reproductive System: Roles in Gonad Development and Diseases

N6-methyladenosine (m⁶A) is the most prevalent chemical modification in eukaryotic messenger RNAs. By participating in various RNA-related bioprocesses including RNA decay, splicing, transport and translation, m⁶A serves as a pivotal regulator of RNA fate and plays an irreplaceable role in cellular activities. The m⁶A modifications of transcripts are coordinately regulated by methyltransferase “writers” and demethylase “erasers”, and produce variable effects via different m⁶A reading protein “readers”. There is emerging evidence that m⁶A modifications play a critical role in a variety of physiological and pathological processes in the female reproductive system, subsequently affecting female fertility. Here, we introduce recent advances in research on m⁶A regulators and their functions, then highlight the role of m⁶A in gonad development and female reproductive diseases, as well as the underlying mechanisms driving these processes.

Profile of Bile Acid Metabolomics in the Follicular Fluid of PCOS Patients

Polycystic ovary syndrome (PCOS) is a complex heterogeneous endocrine disease affected by genetic and environmental factors. In this manuscript, we aimed to describe the composition of bile acid metabolomics in the follicular fluid (FF) of PCOS. The FF was collected from 31 control patients and 35 PCOS patients diagnosed according to the Rotterdam diagnostic criteria. The Bile Acid Assay Kit and ultra-performance liquid chromatography/tandem mass spectrometry (UPLC-MS/MS) were used in this study to detect the total bile acid and 24 bile acid metabolites. Glycocholic acid (GC3A), taurocholic acid (TCA), glycochenodeoxycholic acid (GCDCA), and chenodeoxycholic acid-3-β-d-glucuronide (CDCA-3Gln) were elevated in the PCOS group. GCDCA was positively correlated with the serum follicle-stimulating hormone (FSH) (r = 0.3787, p = 0.0017) and luteinizing hormone (LH) (r = 0.2670, p = 0.0302). The level of CDCA-3Gln also rose with the increase in antral follicle counts (AFC) (r = 0.3247, p = 0.0078). Compared with the control group, the primary bile acids (p = 0.0207) and conjugated bile acids (p = 0.0283) were elevated in PCOS. For the first time, our study described the changes in bile acid metabolomics in the FF of PCOS patients, suggesting that bile acids may play an important role in the pathogenesis of PCOS.