miR‑423 sponged by lncRNA NORHA inhibits granulosa cell apoptosis

Background Atresia and degeneration,a follicular developmental fate that reduces female fertility and is triggered by granulosa cell(GC)apoptosis,have been induced by dozens of miRNAs.Here,we report a miRNA,miR-423,that inhibits the initiation of follicular atresia(FA),and early apoptosis of GCs.Results We showed that miR-423 was down-regulated during sow FA,and its levels in follicles were negatively correlated with the GC density and the P4/E2 ratio in the follicular fluid in vivo.The in vitro gain-of-function experiments revealed that miR-423 suppresses cell apoptosis,especially early apoptosis in GCs.Mechanically speaking,the miR-423 targets and interacts with the 3’-UTR of the porcine SMAD7 gene,which encodes an apoptosis-inducing factor in GCs,and represses its expression and pro-apoptotic function.Interestingly,FA and the GC apoptosis-related lncRNA NORHA was demonstrated as a ceRNA of miR-423.Additionally,we showed that a single base deletion/insertion in the miR-423 promoter is significantly associated with the number of stillbirths(NSB)trait of sows.Conclusion These results demonstrate that miR-423 is a small molecule for inhibiting FA initiation and GC early apoptosis,suggesting that treating with miR-423 may be a novel approach for inhibiting FA initiation and improving female fertility.

NORHA,a novel follicular atresia-related lncRNA,promotes porcine granulosa cell apoptosis via the miR-183-96-182 cluster and FoxO1 axis

Background:Follicular atresia has been shown to be strongly associated with a low follicle utilization rate and female infertility,which are regulated by many factors such as microRNAs(miRNAs),which constitute a class of noncoding RNAs(ncRNAs).However,little is known about long noncoding RNAs(lncRNAs),which constitute another ncRNA family that regulate follicular atresia.Results:A total of 77 differentially expressed lncRNAs,including 67 upregulated and 10 downregulated lncRNAs,were identified in early atretic follicles compared to healthy follicles by RNA-Sequencing.We characterized a noncoding RNA that was highly expressed in atretic follicles(NORHA).As an intergenic lncRNA,NORHA was one of the upregulated lncRNAs identified in the atretic follicles.To determine NORHA function,RT-PCR,flow cytometry and western blotting were performed,and the results showed that NORHA was involved in follicular atresia by influencing GC apoptosis with or without oxidative stress.To determine the mechanism of action,bioinformatics analysis,luciferase reporter assay and RNA immunoprecipitation assay were performed,and the results showed that NORHA acted as a‘sponge’,that directly bound to the miR-183-96-182 cluster,and thus prevented its targeted inhibition of FoxO1,a major sensor and effector of oxidative stress.Conclusions:We provide a comprehensive perspective of lncRNA regulation of follicular atresia,and demonstrate that NORHA,a novel lncRNA related to follicular atresia,induces GC apoptosis by influencing the activities of the miR-183-96-182 cluster and FoxO1 axis.

Morphological and Hormonal Identifi cation of Porcine Atretic Follicles and Relationship Analysis of Hormone Receptor Levels During Granulosa Cell Apoptosis In vivo

Recent reports have demonstrated that follicular atresia is initiated or caused by granulosa cell apoptosis followed by theca cell degeneration in mammalian ovaries, but the mechanism of follicular atresia is still to be elucidated. Therefore, our present study was designed to examine our hypothesis that the changes of follicular microenvironment induce the granulosa cell apoptosis during pocrine follicular atresia in vivo. We firstly isolated intact porcine antral follicles and identified them into three groups, healthy follicles （HF）, early atretic follicles （EAF） and progressed atretic follicles （PAF） through morphology and histology. To further confirm their status, we detected hormone levels in follicular fluids and the expression level of apoptosis gene Bax in granulosa cells. The rate of progesterone （P） and estradiol （E2） was increased with the expression of Bax, indicating hormone can be used as a marker of granulosa cell apoptosis or follicular atresia. Finally, we analyzed the expression level of hormone receptor genes in granulosa cells and their relationship with follicular atresia. In PAF, the expression of Progesterone receptor （PGR） was increased significantly while estradiol receptor （ER） had no notable changes, which suggesting the increased-PGR accelerated the effect of P-stimulated granulosa cell apoptosis. The dramatic increasing of androgen receptor （AR） expression in PAF and the obvious increase of tumor necrosis factor-u receptor （TNFR） in EAF indicated that there are different pathways regulating granulosa cell apoptosis during follicular atresia. Together, our results suggested that different pathways of granulosa cell apoptosis was induced by changing the follicular microenvironment during follicular atresia.

Effects of chronic heat stress on granulosa cell apoptosis and follicular atresia in mouse ovary

Background： Heat stress is known to alter follicular dynamics and granulosa cell function and may contribute to the diminished reproductive efficiency commonly observed in mammals during the summer. Although several investigators have studied heat-induced ovarian injury, few reports have focused on the effects of chronic heat stress on ovarian function and the molecular mechanisms through which it induces ovarian injury.Methods： In Exp. 1, 48 female mice were assigned to a control or heat-stressed treatment. After exposure to a constant temperature of 25 ℃ for 7, 14, 21 or 28 d（n = 6） or to 42 ℃ for 3 h per d for 7, 14, 21 or 28 d（n = 6）, the mice were euthanized and their ovaries were analyzed for follicular atresia, granulosa cell apoptosis, changes in the abundance of HSP70 protein and serum concentrations of estradiol. In Exp. 2, the expression of HSP70 and aromatase was quantified in antral follicles cultured in vitro at 37 or 42 ℃ for 24 h. In Exp. 3, granulosa cells from ovaries maintained at 37 or 41 ℃ for 2 h were analyzed for their expression of HSP70, Bim, caspase-3 and cleaved caspase-3.Results： In Exp. 1, body weight and food intake of heat-stressed mice decreased（P 〈 0.05） compared with control mice while the concentration of estradiol in serum was lower（P 〈 0.05） in heat-stressed mice than in control mice. Compared with control mice, the percentage of atretic follicles and the number of antral follicles with severe apoptotic signals were increased（P 〈 0.05） after 21 d of heat-stressed treatment. HSP70 protein was more abundant（P 〈 0.05） in heat-stressed mice than control mice. In Exp. 2, heat stress increased HSP70 and decreased aromatase proteins（P 〈 0.05） in antral follicles. In Exp. 3, TUNEL-positive granulosa cells from heat-stressed ovaries were observed concomitant with a significant increase in HSP70, Bim and cleaved caspase-3 protein.Conclusion： Heat-stress in mice decrease estradiol in serum and aromatase in antral follicles but increased number of atretic follicles and granulosa cell undergoing apoptosis which may explain the decreased fertility commonly observed in heat-stressed animals.

Multi‑omics analysis reveals gut microbiota‑ovary axis contributed to the follicular development difference between Meishan and Landrace×Yorkshire sows

Background The mechanism by which Meishan(MS)sows are superior to white crossbred sows in ovarian follicle development remains unclear.Given gut microbiota could regulate female ovarian function and reproductive capacity,this study aimed to determine the role of gut microbiota-ovary axis on follicular development in sows.Methods We compared the ovarian follicular development,gut microbiota,plasma metabolome,and follicular fluid metabolome between MS and Landrace×Yorkshire(L×Y)sows.A H_(2)O_(2)-induced cell apoptosis model was used to evaluate the effects of multi-omics identified metabolites on the apoptosis of porcine ovarian granulosa cells in vitro.Results Compared with L×Y sows,MS sows have greater ovary weight and improved follicular development,including the greater counts of large follicles of diameter≥5 mm,secondary follicles,and antral follicles,but lesser atretic follicles.The ovarian granulosa cells in MS sows had alleviated apoptosis,which was indicated by the increased BCL-2,decreased caspases-3,and decreased cleaved caspases-3 than in L×Y sows.The ovarian follicular fluid of MS sows had higher concentrations of estradiol,progesterone,follicle-stimulating hormone,luteinizing hormone,and insulin like growth factor 1 than L×Y sows.Gut microbiota of MS sows formed a distinct cluster and had improved alpha diversity,including increased Shannon and decreased Simpson than those of L×Y sows.Corresponding to the enhanced function of carbohydrate metabolism and elevated short-chain fatty acids(SCFAs)in feces,the differential metabolites in plasma between MS and L×Y sows are also mainly enriched in pathways of fatty acid metabolism.There were significant correlations among SCFAs with follicular development,ovarian granulosa cells apoptosis,and follicular fluid hormones,respectively.Noteworthily,compared with L×Y sows,MS sows had higher follicular fluid SCFAs concentrations which could ameliorate H_(2)O_(2)-induced porcine granulosa cells apoptosis in vitro.Conclusion MS sows have more secondary and antral follicles,but fewer atretic follicles and apoptotic ovarian granulosa cells,as well as harbored a distinctive gut microbiota than L×Y sows.Gut microbiota may participate in regulating ovarian follicular development via SCFAs affecting granulosa cells apoptosis in sows.