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Recurrent miscarriage (RM) is related to the dysfunction of extravillous trophoblast cells (EVTs), but the comprehensive mechanisms remain largely unexplored. We analyzed single-cell RNA sequencing (scRNA-seq), bulk RNA sequencing and microarray datasets obtained from Gene Expression Omnibus (GEO) database to explore the hub genes in the mechanisms of RM. We identified 1724 differentially expressed genes (DEGs) in EVTs from the RM, and they were all expressed along the trajectory of EVTs. These DEGs were associated with hypoxia and glucose metabolism. Single-cell Regulatory Network Inference and Clustering (SCENIC) analysis revealed that E2F transcription factor (E2F) 8 (E2F8) was a key transcription factor for these DEGs. And the expression of ENO1 can be positively regulated by E2F8 via RNA sequencing analysis. Subsequently, we performed immunofluorescence assay (IF), plasmid transfection, western blotting, chromatin immunoprecipitation (ChIP), real-time quantitative polymerase chain reaction (qRT-PCR), and transwell assays for validation experiments. We found that the expression of alpha-Enolase 1 (ENO1) was lower in the placentas of RM. Importantly, E2F8 can transcriptionally regulate the expression of ENO1 to promote the invasion of trophoblast cells by inhibiting secreted frizzled-related protein 1/4 (SFRP1/4) to activate Wnt signaling pathway. Our results suggest that ENO1 can promote trophoblast invasion via an E2F8-dependent manner, highlighting a potential novel target for the physiological mechanisms of RM., (© 2024 Federation of American Societies for Experimental Biology.)

In Brief: Preeclampsia (PE) is a severe complication that leads to major maternal and fetal mortality and morbidity, and one of its causes is extravillous trophoblast (EVT) dysfunction. This study revealed the role of CD74 in the invasion and proliferation of EVTs., Abstract: PE is a severe hypertensive disorder during pregnancy, and one of its causes is the dysfunction of EVTs. In this study, we analyzed single-cell RNA sequencing (scRNA-seq) data of placentas from PE patients and the sirtuin 1 (SIRT1) heterozygous knockout mouse model, which exhibited typical PE-like symptoms. We identified 134 differentially expressed genes (DEGs) with similar trends in EVTs of PE patients and in parietal trophoblast giant cells (P-TGCs) of Sirt1-/- (HO) placentas from Sirt1+/- (HE) pregnant mice. Interestingly, Kyoto Encyclopedia of Genes and Genomes analysis showed that 134 overlapping genes were related to the MAPK signaling pathway. We validated several DEGs using immunofluorescence at the protein level. Finally, we selected CD74 for further experiments, which showed a decrease in EVTs of PE patients and in P-TGCs of Sirt1-/- placentas from Sirt1+/- pregnant mice. Additionally, cell proliferation assays and transwell assays showed that the proliferation and invasion abilities were decreased in CD74 knockdown HTR8/SVneo cells using lentivirus transfection, which can be improved by adding the SIRT1 agonist SRT1720 or metformin, an agonist of the MAPK signaling pathway. Importantly, the expression of CD74 can be positively regulated by SIRT1. These data suggest that CD74 plays an important protective role in the pathogenesis of preeclampsia by regulating the MAPK signaling pathway, which can be regulated by SIRT1.

Transformation of the spiral arteries including the displacement of vascular endothelial cells by extravillous trophoblasts is an essential prerequisite to normal placentation. However, the activated endothelial cells resist the invasion of trophoblasts, which contributes to the pathologies of some pregnant disorders. Our previous studies have demonstrated that Cyclosporin A (CsA) promotes the migration and invasion of human first-trimester trophoblasts. In the present study, we further investigated whether CsA could promote the ability of trophoblasts to displace the activated human umbilical vein endothelial cell (HUVEC) monolayers and the possible molecular mechanisms. Human choriocarcinoma Jar cells were used as a model of invasive trophoblasts. CsA pretreated JAR cells (red) were added to HUVEC monolayers (green) activated with either necrotic JAR cells or tumor necrosis factor alpha (TNFα). The ability of JAR cells to displace HUVECs from the monolayers was examined by confocal microscopy. The effects of CsA on Titin and E-cadherin expression, matrix metalloproteinases (MMPs) activity and CXCL12 secretion of JAR cells were evaluated by western blot, gelatin zymography and enzyme-linked immunosorbent assay (ELISA), respectively. We found that CsA pretreatment increased the ability of JAR cells to displace activated HUVECs from the monolayers. However, the displacement was reduced by untreated JAR cells. Moreover, CsA pretreatment up-regulated Titin expression, down-regulated E-cadherin expression, improved MMP2 and MMP9 activity, and increased the CXCL12 secretion in JAR cells. These results indicate that CsA may improve the trophoblast invasion to activated HUVEC monolayers through different downstream targets, and ultimately, improve the transformation and remodeling of spiral arteries.

Previous studies showed that aberrant HLA-G expression in trophoblast cells plays important roles in trophoblast invasion; however, the mechanisms remain to be explored. In this study, we found that suppressed HLA-G expression could dramatically decrease the mRNA and protein expression levels of matrix metalloproteinase 2 and matrix metalloproteinase 9, and in the proteome assay, there were 3 identified proteins namely, prefoldin 1, eukaryotic translation elongation factor 2 and malate dehydrogenase 2, which were verified by Western blot and known to be associated with invasion, cell cycle and cell metabolism, respectively. Collectively, our study indicated a potential involvement of HLA-G in autocrine networks that may regulate prefoldin, MMPs and trophoblast invasion at the maternal-fetal interface in human pregnancy.