MiR-124-3p negatively impacts embryo implantation via suppressing uterine receptivity formation and embryo development

Whole transcriptome analysis in oviduct provides insight into microRNAs and ceRNA regulative networks that targeted reproduction of goat (Capra hircus)

BACKGROUND

Reproduction traits are crucial for livestock breeding and represent key economic indicators in the domestic goat (Capra hircus) industry. The oviduct, a critical organ in female mammals, plays a pivotal role in several reproductive processes; however, its molecular mechanisms remain largely unknown. Non-coding RNA and mRNAs are essential regulatory elements in reproductive processes; yet their specific roles and regulatory networks in goat oviducts remain unclear.

RESULTS

In this study, we conducted small RNA sequencing of the oviduct in high- and low-fecundity goats during the follicular (FH and FL groups, n = 10) and luteal (LH and LL groups, n = 10) phase, profiling 20 tissue samples. Combinatorial whole-transcriptome expression profiles were applied to the same samples to uncover the competitive endogenous RNA (ceRNA) regulation network associated with goat fecundity. RT-qPCR was employed to validate the miRNA profiling results, and ceRNA regulatory networks were analyzed through luciferase assay. Gene set enrichment analysis (GSEA) confirmed that the cytokine-cytokine receptor interaction and TGF-β signaling pathway, both related to embryonic development, were enriched in DEM target genes. Additionally, miR-328-3p, a core miRNA, targets SMAD3 and BOP1, which are involved in the negative regulation of cell growth and embryonic development. TOB1 and TOB2, targeted by miR-204-3p, regulate cell proliferation via the protein kinase C-activating G-protein coupled receptor signaling pathway. Analyses of ceRNA regulatory networks revealed that LNC_005981 - miR-328-3p - SMAD3 and circ_0021923 - miR-204-3p - DOT1L may affect goats' reproduction, findings that were validated using luciferase assay.

CONCLUSION

Analysis of whole-transcriptome profiling of goat oviducts identified several key miRNAs and ceRNAs that may regulate oocyte maturation, embryo development, and the interactions between the oviduct and gametes/early embryos, providing insights into the molecular mechanisms of reproductive regulatory networks.

MicroRNAs, endometrial receptivity and molecular pathways

MicroRNAs (miRNAs) are a type of specific molecules that control the activities of the uterus, such as the process of cellular maturing and evolution. A lot of substances like growth factors, cytokines, and transcription factors play a role in embryo-endometrial interaction. MiRNAs could regulate various these factors by attaching to the 3' UTR of their mRNAs. Moreover, current research show that miRNAs participate in formation of blood vessels in endometrium (miR-206, miR-17-5p, miR-16-5p…), decidualization (miR-154, miR-181, miR-9…), epithelial-mesenchymal transition (miR-30a-3p), immune response (miR-888, miR-376a, miR-300…) embryo attachment (miR-145, miR-27a,451…) and pinopod formation (mir-223-3p, mir-449a, mir-200c). In this study, the focus is on the role of miRNAs in managing the uterus' receptivity to an embryo and its ability to facilitate attachment. More specifically, we are exploring the mechanisms by which miRNAs regulate the presence of specific molecules involved in this crucial physiological process.

Altered DNA methylation and Dnmt expression in obese uterus may cause implantation failure

Obesity is defined by increased adipose tissue volume and has become a major risk factor for reproduction. Recent studies have revealed a substantial link between obesity and epigenetics. The epigenome is dynamically regulated mainly by DNA methylation. DNA methylation, which is controlled by DNA methyltransferases (Dnmts), has been widely studied because it is essential for imprinting and regulation of gene expression. In our previous study, we showed that the levels of Dnmt1, Dnmt3a and global DNA methylation was dramatically altered in the testis and ovary of high-fat diet (HFD)-induced obese mice. However, the effect of HFD on Dnmts and global DNA methylation in mouse uterus has not yet been demonstrated. Therefore, in the present study, we aimed to evaluate the effect of HFD on the level of Dnmt1, Dnmt3a, Dnmt3b, Dnmt3l and global DNA methylation in uterus. Our results showed that HFD significantly altered the levels of Dnmts and global DNA methylation in the uterus. The total expression of Dnmt1, Dnmt3a and Dnmt3b was significantly upregulated, while level of Dnmt3l and global DNA methylation were dramatically decreased (p < 0.05). Furthermore, we observed that the expression of Dnmt3b and Dnmt3l was significantly increased in endometrium including gland and epithelium (p < 0.05). Although Dnmt3b was the only protein whose expression significantly increased, the level of global DNA methylation and Dnmt3l significantly decreased in stroma and myometrium (p < 0.05). In conclusion, our results show for the first time that obesity dramatically alters global DNA methylation and expression of Dnmts, and decreased DNA methylation and Dnmt expression may cause abnormal gene expression, especially in the endometrium.

Chronic exposure to tire rubber-derived contaminant 6PPD-quinone impairs sperm quality and induces the damage of reproductive capacity in male mice

It has been reported that N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine-quinone (6PPD-Q), a derivative of the tire antioxidant, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD), exhibits acute toxicity towards organisms. However, the possible reproductive toxicity of 6PPD-Q in mammals has rarely been reported. In this study, the effects of 6PPD-Q on the reproductive toxicity of C57Bl/6 male mice were assessed after exposure to 6PPD-Q for 40 days at 4 mg/kg body weight (bw). Exposure to 6PPD-Q not only led to a decrease in testosterone levels but also adversely affected semen quality and in vitro fertilization (IVF) outcomes, thereby indicating impaired male fertility resulting from 6PPD-Q exposure. Additionally, transcriptomic and metabolomic analyses revealed that 6PPD-Q elicited differential expression of genes and metabolites primarily enriched in spermatogenesis, apoptosis, arginine biosynthesis, and sphingolipid metabolism in the testes of mice. In conclusion, our study reveals the toxicity of 6PPD-Q on the reproductive capacity concerning baseline endocrine disorders, sperm quality, germ cell apoptosis, and the sphingolipid signaling pathway in mice. These findings contribute to an enhanced understanding of the health hazards posed by 6PPD-Q to mammals, thereby facilitating the development of more robust safety regulations governing the utilization and disposal of rubber products.