The distribution and expression of vascular endothelial growth factor A (VEGFA) during follicular development and atresia in the pig

The vascular endothelial growth factor (VEGF) system as a key regulator of ovarian follicle angiogenesis and growth

The vascular endothelial growth factor-A (VEGFA) system is a complex set of proteins, with multiple isoforms and receptors, including both angiogenic (VEGFxxx, VEGFR2) and antiangiogenic members (VEGFxxxb, VEGFR1 and soluble forms of VEGFR). The members of the VEGF system affect the proliferation, survival, and migration of endothelial and nonendothelial cells and are involved in the regulation of follicular angiogenesis and development. The production of VEGF by secondary follicles stimulates preantral follicular development by directly affecting follicular cells and promoting the acquisition of the follicular vasculature and downstream antrum formation. Additionally, the pattern of expression of the components of the VEGF system may provide a proangiogenic milieu capable of triggering angiogenesis and stimulating follicular cells to promote antral follicle growth, whereas, during atresia, this milieu becomes antiangiogenic and blocks follicular development.

Effect of Angelica Sinensis extract on the angiogenesis of preovulatory follicles (F1-F3) in late-phase laying hens

In order to form follicles and ovulate normally, there must be abundant blood vessels. Angelica sinensis (Oliv.) Diels (AS), as a traditional Chinese medicinal herb, has the effects of tonifying the blood and activating the blood circulation. However, the effect of AS on angiogenesis in hen-follicles remains to be discovered. In this study, we identified vascular richness, granulosa layer thickness, expression of platelet endothelial cell adhesion molecule-1 (CD31) and the content of vascular endothelial growth factor A (VEGFA) in granulosa layers to elucidate the effect of AS extract on angiogenesis in preovulatory follicles (F1-F3) of late-phase laying hens (75 wk). Based on network pharmacology, we predicted beta-sitosterol, ferulic acid, and caffeic acid as the main active components of AS, and hypoxia-inducible factor-1α (HIF1α), vascular endothelial growth factor receptor 2 (VEGFR2) as hub targets of AS in angiogenesis. The intersection targets were enriched by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, and the hub targets were verified by immunofluorescence and western blot. Molecular docking of active components with hub targets was performed and verified in vitro. The results showed that AS extract promoted angiogenesis in preovulatory follicles and increased granulosa cell layer thickness, CD31 expression and content of VEGFA. Experiments in vitro and in vivo demonstrated that AS extract promoted the expression of HIF1α and VEGFA, up-regulated the phosphorylation levels of VEGFR2. These results further demonstrated the reliability of molecular docking and network pharmacology findings. In summary, AS extract can promote angiogenesis in the preovulatory follicles in late-phase laying hens.

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.

Non-targeted Metabolomics Reveals Metabolic Characteristics of Porcine Atretic Follicles

Follicular atresia is one of the main factors limiting the reproductive power of domestic animals. At present, the molecular mechanisms involved in porcine follicular atresia at the metabolic level remain unclear. In this study, we divided the follicles of Bama Xiang pigs into healthy follicles (HFs) and atretic follicles (AFs) based on the follicle morphology. The expression of genes related to atresia in granulosa cells (GCs) and the concentration of hormones in the follicular fluid (FF) from HFs and AFs were detected. We then used liquid chromatography–mass spectrometry-based non-targeted metabolomic approach to analyze the metabolites in the FF from HFs and AFs. The results showed that the content of estradiol was significantly lower in AFs than in HFs, whereas that of progesterone was significantly higher in AFs than that in HFs. The expression of BCL2, VEGFA, and CYP19A1 was significantly higher in HFs than in AFs. In contrast, the expression of BAX and CASPASE3 was significantly lower in HFs. A total of 18 differential metabolites (DMs) were identified, including phospholipids, bioactive substances, and amino acids. The DMs were involved in 12 metabolic pathways, including arginine biosynthesis and primary bile acid biosynthesis. The levels of eight DMs were higher in the HF group than those in the AF group (p < 0.01), and those of 10 DMs were higher in the AF group than those in the HF group (p < 0.01). These findings indicate that the metabolic characteristics of porcine AFs are lower levels of lipids such as phospholipids and higher levels of amino acids and bile acids than those in HFs. Disorders of amino acid metabolism and cholic acid metabolism may contribute to porcine follicular atresia.

Effect of Concentrate Supplementation on the Expression Profile of miRNA in the Ovaries of Yak during Non-Breeding Season

Simple Summary

Yak (Bos grunniens) is an important and remarkable livestock species that survives in the challenging environment of the Qinghai–Tibetan Plateau. However, its growth rate is slower and reproductive ability is generally lower than cattle. This may be due to the yak living in high altitudes all year round where in the whole year, grasses are only available in July, August, and September (warm season), and from November to the next year of May (cold season), there is a scarcity of pastures. So, the reproductive efficiency of yak is very low. Meanwhile, it has been reported that enhanced nutrition improves the reproductive efficiency of animals. Therefore, this study aimed to explore the effects of supplemental nutrition on the growth traits and reproductive performance of yaks in the cold season. In addition, miRNAs related to yak reproductive traits were screened by miRNA sequencing technology. This research might be helpful for improving the reproductive potential of yak during the non-breeding season.

Abstract

Yak (Bos grunniens) is an important and remarkable livestock species that survives in the challenging environment of the Qinghai–Tibetan Plateau. However, its growth rate is slower and reproductive potential is generally lower than cattle. Meanwhile, it has been reported that enhanced nutrition improves the reproductive efficiency of animals. The purpose of this study was to investigate the effect of concentrate supplementation on the miRNA expression profile in the ovaries of yak during the non-breeding season. The study displayed that non-breeding season supplementation significantly improved growth performance, serum biochemical indicators, and reproductive hormone concentrations in yaks. In this study, we also examined the differential expression analysis of miRNA in the ovaries of yak during non-breeding seasons using Illumina Hiseq sequencing technology. As a result, 51 differentially expressed miRNAs were found in the experimental group (CS) and control group (CON). Gene Ontology (go) and Kyoto Genome Encyclopedia (KEGG) analysis of target genes showed that beta-alanine metabolism; tryptophan metabolism; sphingolipid metabolism; alanine, aspartate and glutamate metabolism; and the inositol phosphate metabolism pathway attracted our attention. Based on qRT-PCR, seven miRNAs were assessed to verify the accuracy of the library database. We predicted and identified potential miRNA target genes, including LEP, KLF7, VEGFA, GNAQ, GTAT6, and CCND2. miRNA and corresponding target genes may regulate yaks’ seasonal reproduction through their nutritional status. This study will provide an experimental basis for improving the reproductive efficiency of yaks by supplementation in the non-breeding season.

miR-361-5p Mediates SMAD4 to Promote Porcine Granulosa Cell Apoptosis through VEGFA

Follicular atresia is an inevitable degenerative process that occurs in mammalian ovarian follicles. The molecular events involved in atresia, particularly granulosa cell apoptosis, have long attracted researchers’ attention. Vascular endothelial growth factor A (VEGFA) is downregulated during follicular atresia in porcine ovaries and serves as an inhibitor of apoptosis in granulosa cells. In addition, transforming growth factor (TGF)-βsignaling has been considered a central trigger in granulosa cell apoptosis. However, the link between TGF-β signaling and VEGFA is unknown. We proved that miR-361-5p is significantly upregulated during the atresia process and that it promotes GC apoptosis by directly targeting the VEGFA 3′UTR. In addition, we revealed that the miR-361-5p coding gene MIR361 was significantly downregulated by SMAD4, the central intracellular mediator of TGF-β signaling, that bound to the MIR361 promoter. In conclusion, our findings expanded what is known about VEGFA posttranscriptional regulation and revealed a complete SMAD4/miR-361-5p/VEGFA regulatory network in ovarian granulosa cell apoptosis. These data provide useful references for follicular atresia and ovarian physiological function studies.