The role of PGRMC2 in the trophoblast invasion.

Proper extravillous trophoblasts (EVTs) invasion is essential for normal placentation and pregnancy. However, the molecular mechanisms by which cytotrophoblasts (CTBs) differentiate into EVTs are unclear. We discovered that in the first trimester placentae, PGRMC2 was highly expressed in syncytiotrophoblast (STB) but significantly lower in EVTs and CTBs, indicating a divergent role for PGRMC2 in trophoblast functions. We aim to examine the role of PGRMC2 in EVTs invasion mediated by both intracellular and extracellular signals. PGRMC2 knockdown and overexpression cells were established in HTR8/SVneo cells, a first-trimester EVTs-derived cell model, by transfection with siRNA or PGRMC2 plasmids, respectively. We studied cell morphology through microscope observation and immunofluorescent staining for an epithelial biomarker, cytokeratin, and a mesenchymal biomarker, vimentin. The proliferation, invasiveness, and angiogenesis of HTR8/SVneo cells were assessed using an MTS assay, a 24-well Matrigel invasion chamber plates, and a tube formation assay, respectively. The expression of Hypoxia-Inducible Factor 1 α (HIF1α) was examined by Western blot and RT-qPCR. The methylation and translocation of HIF1α mRNA were examined by RNA immunoprecipitation and cellular fraction followed by RT-qPCR. Culture supernatants were assessed for mediating the invasiveness of these cells. PGRMC2 knockdown led to cellular morphological changes, specifically, an epithelial-mesenchymal cell transition, enhanced trophoblast proliferation, and invasion, and promoted tube formation. These effects were mediated by the activation of HIF1α and an increased expression of vascular endothelial growth factor A, a HIF1α target gene in PGRMC2 knockdown cells. The inhibition of HIF1α protein degradation through downregulation of HIF1AN and enhanced HIF1α mRNA stability through reduced HIF1A-AS2 and methylation (m6A levels) in HIF1α mRNA were attributed to the sustained activation of HIF1α in PGRMC2 knockdown EVTs. The dysregulation of methyltransferases by PGRMC2 pointed to the decreased mRNA methylation including downregulation of METTL3, METTL14, YTHDC2, and upregulated IGF2BP3. The culture supernatant collected from PGRMC2 knockdown cells did not significantly affect EVT invasion compared to the controls, indicating that extracellular signaling did not robustly regulate EVT invasion in this study. In conclusion, PGRMC2 plays a role in placentation by promoting cell proliferation, invasion, and angiogenesis in EVTs via activation of HIF1α signaling. We thus identified a new function of PGRMC2 and provide insights on understanding the mechanisms of trophoblast invasion. © The Author(s) 2023. Published by Oxford University Press on behalf of Society for the Study of Reproduction. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Citation

Tae Yokouchi-Konishi, Yongjie Liu, Liping Feng. The role of PGRMC2 in the trophoblast invasion. Biology of reproduction. 2023 Sep 04

PMID: 37665239

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