Hypermethylation and low expression of FOXM1 predisposes women to unexplained Recurrent Miscarriage by impairing Trophoblast Stem Cell Proliferation

Recurrent miscarriage (RM) is a distressing pregnancy complication, while the etiology of RM remains elusive. Increasing evidence indicates the relevance of dysregulation of the trophoblast stem cells (TSCs) to the pathogenesis of RM. Data analysis identified TEAD4 and Forkhead box M1 (FOXM1) as potential factors linked to RM. Given previous evidence of impaired TEAD4 expression in CTB progenitor cells, our study concentrates on FOXM1. FOXM1 is a typical transcription factor that plays principal roles in many pathophysiological processes. However, how FOXM1 functions in TSCs and RM has not been completely elucidated. Therefore, this study aims to study the role of FOXM1 in TSCs homeostasis regulation and its implications in RM. We decipher the underlying regulation mechanism of FOXM1 in hTSCs particularly using RNA-seq, CUT&Tag, ChIP-qPCR and sodium bisulfite conversion methods for methylation analysis. We reveal that FOXM1 is specifically expressed in cytotrophoblasts (CTBs) and extravillous cytotrophoblasts (EVTs) but absent in syncytiotrophoblasts (STBs), and provide evidence for a significant correlation between the downregulation of FOXM1 and the incidence of RM. Furthermore, we demonstrate that FOXM1 plays a pivotal role in regulating hTSCs proliferation and cell cycle by controlling the transcription of CDKN3, CCNB2, CCNA2, MAD2L1 and CDC25C. Notably, we observed that the downregulation of FOXM1 in RM corresponds to hypermethylation in its promoter region. These findings collectively shed light on the involvement FOXM1 in trophoblast regulation and offer a new perspective on RM.