Peri-implantation expression and regulation of ITGB8 in goat uterus

Pericardial delta like non-canonical NOTCH ligand 1 (Dlk1) augments fibrosis in the heart through epithelial to mesenchymal transition

BACKGROUND

Heart failure due to myocardial infarction (MI) involves fibrosis driven by epicardium-derived cells (EPDCs) and cardiac fibroblasts, but strategies to inhibit and provide cardio-protection remains poor. The imprinted gene, non-canonical NOTCH ligand 1 (Dlk1), has previously been shown to mediate fibrosis in the skin, lung and liver, but very little is known on its effect in the heart.

METHODS

Herein, human pericardial fluid/plasma and tissue biopsies were assessed for DLK1, whereas the spatiotemporal expression of Dlk1 was determined in mouse hearts. The Dlk1 heart phenotype in normal and MI hearts was assessed in transgenic mice either lacking or overexpressing Dlk1. Finally, in/ex vivo cell studies provided knowledge on the molecular mechanism.

RESULTS

Dlk1 was demonstrated in non-myocytes of the developing human myocardium but exhibited a restricted pericardial expression in adulthood. Soluble DLK1 was twofold higher in pericardial fluid (median 45.7 [34.7 (IQR)) μg/L] from cardiovascular patients (n = 127) than in plasma (median 26.1 μg/L [11.1 (IQR)]. The spatial and temporal expression pattern of Dlk1 was recapitulated in mouse and rat hearts. Similar to humans lacking Dlk1, adult Dlk1-/- mice exhibited a relatively mild developmental, although consistent cardiac phenotype with some abnormalities in heart size, shape, thorax orientation and non-myocyte number, but were functionally normal. However, after MI, scar size was substantially reduced in Dlk1-/- hearts as compared with Dlk1+/+ littermates. In line, high levels of Dlk1 in transgenic mice Dlk1fl/fl xWT1GFPCre and Dlk1fl/fl xαMHCCre/+Tam increased scar size following MI. Further mechanistic and cellular insight demonstrated that pericardial Dlk1 mediates cardiac fibrosis through epithelial to mesenchymal transition (EMT) of the EPDC lineage by maintaining Integrin β8 (Itgb8), a major activator of transforming growth factor β and EMT.

CONCLUSIONS

Our results suggest that pericardial Dlk1 embraces a, so far, unnoticed role in the heart augmenting cardiac fibrosis through EMT. Monitoring DLK1 levels as well as targeting pericardial DLK1 may thus offer new venues for cardio-protection.

Epidermal growth factor: Expression in goat endometrial epithelia during early pregnancy and regulation by interferon tau and FOXO1

In ruminants, establishment and maintenance of pregnancy depends upon a well-coordinated interaction between the conceptus and the maternal endometrium. Epidermal growth factor (EGF) is important for embryo implantation and pregnancy establishment. However, the regulatory mechanisms of EGF expression remain unclear. FOXO1, a member of the Forkhead box O (FOXO) subfamily of transcription factors, is currently accepted as a novel endometrial receptivity marker for humans and mice owing to its timely and specific expression at the window of implantation. In this study, we examined the spatiotemporal expression profile of EGF in goat uterus during early pregnancy (Day 0 to Day 50 of pregnancy) and verified that EGF expression was regulated by FOXO1 and interferon tau (IFNT). Our results showed that EGF was highly expressed in the luminal epithelium (LE) and the glandular epithelium (GE) during conceptus adhesion (Day 16 to Day 25 of pregnancy). After implantation, EGF protein signals were continuously detected in the endometrial epithelia and appeared in the conceptus trophectoderm. Furthermore, EGF expression could be up-regulated by IFNT in goat uterus and primary endometrial epithelium cells (EECs). The luciferase assay results showed that FOXO1 could promote EGF transcription by binding to its promoter. And FOXO1 positively regulates EGF expression in goat EECs. These findings contribute to better understanding the role and regulation mechanisms of EGF during ruminant early pregnancy.

An IFNT/FOXO1/PTGS2 axis regulates prostaglandin F2α synthesis in goat uterus during early pregnancy

In ruminants, IFN-tau (IFNT) regulates the production of prostaglandins (PG) in the endometrium, which is crucial for conceptus adhesion. However, the related molecular regulatory mechanisms remain unclear. Forkhead box O1 (FOXO1), a member of the FOXO subfamily of transcription factors, is known to be important for mouse implantation and decidualization. In this study, we determined the spatiotemporal expression profile of FOXO1 in goat endometrium during early pregnancy. FOXO1 was highly expressed in the glandular epithelium since the onset of conceptus adhesion (d 16 of pregnancy). Then, we validated that FOXO1 could bind to the promoter of prostaglandin-endoperoxide synthase 2 (PTGS2) and increase its transcription. And the expression profile of PTGS2 was similar to that of FOXO1 in the peri-implantation uterus. Moreover, IFNT could upregulate the levels of FOXO1 and PTGS2 in goat uterus and primary endometrial epithelium cells (EEC). In EEC, the intracellular content of PGF2α was positively correlated with the levels of IFNT and FOXO1. Altogether, we found an IFNT/FOXO1/PTGS2 axis that controls the synthesis of PGF2α but not prostaglandin E2 in goat uterine glands. These findings contribute to better understanding the function of FOXO1 in the reproductive physiology of goats and provide more insights into the implantation of small ruminants.

USP18 promotes endometrial receptivity via the JAK/STAT1 and the ISGylation pathway

Interferon-tau (IFNT), a pregnancy recognition signal in ruminants, promotes the establishment of endometrial receptivity by inducing the expression of interferon-stimulated genes (ISGs) via the Janus kinase/signal transducer and activator of transcription (JAK/STATs) signaling pathway. However, the precise mechanisms remain largely unknown. Ubiquitin-specific protease 18 (USP18) acts specifically on the ISGylation modification system to exert deubiquitination and participates in the regulation of the type I IFN signaling pathway. The purpose of this study was to determine the role and mechanism of USP18 on endometrial receptivity in goat. USP18 was mainly localized in the uterine luminal and glandular epithelium, and its expression levels were significantly increased from days 5-18 of early pregnancy. Progesterone (P₄), estradiol (E₂), and IFNT significantly stimulated USP18 expression in goat endometrial epithelial cells (gEECs) cultured in vitro. Meanwhile, the markers of endometrial receptivity HOXA11, ITGB1, ITGB3, and ITGB5 were significantly upregulated after USP18 overexpression in gEECs. However, USP18 interference significantly inhibited the expression of HOXA10, ITGB1, ITGB3, and ITGB5 in gEECs. In addition, both the phosphorylation levels of STAT1 and the expression of ISGylation-modified proteins were significantly increased after USP18 silencing in gEECs. Furthermore, pretreatment with the STAT1 inhibitor Fludara markedly restored the effect of USP18 interference in gEECs. In summary, USP18 may play an important role in promoting goat endometrial receptivity by regulating the JAK/STAT1 pathway and ISGylation.

A regulatory network controlling ovarian granulosa cell death

Follicular atresia triggered by granulosa cell (GC) apoptosis severely reduces female fertility and accelerates reproductive aging. GC apoptosis is a complex process regulated by multiple factors, regulatory axes, and signaling pathways. Here, we report a novel, small regulatory network involved in GC apoptosis and follicular atresia. miR-187, a miRNA down-regulated during follicular atresia in sows, maintains TGFBR2 mRNA stability in sow GCs by directly binding to its 5'-UTR. miR-187 activates the transforming growth factor-β (TGF-β) signaling pathway and suppresses GC apoptosis via TGFBR2 activation. NORHA, a pro-apoptotic lncRNA expressed in sow GCs, inhibits TGFBR2-mediated activation of the TGF-β signaling pathway by sponging miR-187. In contrast, NORFA, a functional lncRNA associated with sow follicular atresia and GC apoptosis, enhances miR-187 and TGFBR2 expression by inhibiting NORHA and activating NFIX. Our findings define a simple regulatory network that controls GC apoptosis and follicular atresia, providing new insights into the mechanisms of GC apoptosis, follicular atresia, and female fertility.

Screening genes related to embryo implantation in Dazu black goats (Capra Hircus) by morphological and transcriptome analyses

Embryo implantation is a critical step in the establishment of pregnancy. However, the mechanisms of embryo implantation during early pregnancy in goats remain unclear due to the lack of published studies examining the genes involved in embryo implantation. As a popular goat breed in southwest China, Dazu black goats (DBGs) are highly adaptable and exhibit high fertility, making this breed a good model in which to study reproductive performance of goats. Here, morphological analysis showed that compared with the non-pregnant (NP) groups, the endometrial thickness of the goats in the P15 and P19 groups (15 and 19-day pregnant groups, respectively) were increased (P < 0.01). Proliferating Cell Nuclear Antigen (PCNA) staining showed that PCNA was expressed in the NP, P15, and P19 groups. Transcriptome analysis was then conducted to identify gene expression patterns in uterine tissue during DBG embryo implantation. By comparing uterine tissue at different stages of embryonic implantation, 48 in NP_vs._P15, 318 in NP_vs._P19, and 1439 in P15_vs._P19, differentially expressed mRNAs were identified. Gene Ontology (GO) enrichments of the differentially expressed genes were enriched in the extracellular region, extracellular space, transporter activity, extracellular region, immune system process, immune response, and defense response etc. Through Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, the biological metabolic pathways with which the differentially expressed genes are associated were explored. Through KEGG analysis, the DBGs were associated with oxidative phosphorylation, complement and coagulation cascades, arginine and proline metabolism, metabolic pathways, arachidonic acid metabolism, and ECM-receptor interaction. These candidate genes (CSF1, C1S, CST6, SLC24A4, HOXA10, HOXA11, MMP9, and ITGA11) and enriched signaling pathways could be valuable references for exploring the molecular mechanisms underlying goat embryo implantation.

Expression and hormone regulation of UCP2 in goat uterus

Pregnancy success is closely related to the molecular mechanisms that control energy metabolism balance. However, the mechanisms have not been fully understood. Uncoupling protein 2 (UCP2) plays a physiological role by regulating energy metabolism in numerous tissues. In this study, we determined the expression and hormone regulation of UCP2 in goat uterus. UCP2 is expressed in the luminal and glandular epithelia of goat uterus during early pregnancy, as revealed by in situ hybridization and immunohistochemistry conducted on pregnant goats. The signals were detected from day 0 (D0) to D30 of pregnancy, though weak on D16 (the adhesion period). The low levels of UCP2 on D16 were confirmed by RT-qPCR and western blot. In goat uterus and endometrial epithelial cells (EECs), UCP2 was up-regulated by progesterone and estrogen. In addition, after goat EECs were treated with genipin (an inhibitor of UCP2), not only UCP2 expression but also cell proliferation was inhibited. Collectively, UCP2 is dynamically expressed in goat uterus and can affect EEC proliferation, suggesting that it may participate in regulating the energy metabolism balance of goat uterus during early pregnancy.