Conclusions
Treatment with a FOXO1 inhibitor during TE induction from naive iPSCs promotes early TE differentiation but hinders the progression of differentiation into ST and EVT. The suppression of ERV-associated genes may be involved in this process.
Methods
We induced TE differentiation from naive iPSCs in the presence or absence of a FOXO1 inhibitor, and the resulting cells were subjected to trophoblast differentiation procedures without the FOXO1 inhibitor. The cells obtained in these processes were assessed for morphology, gene expression, and hCG secretion using phase-contrast microscopy, reverse transcription polymerase chain reaction (RT-PCR), quantitative RT-PCR (RT-qPCR), RNA-seq, immunochromatography, and a chemiluminescent enzyme immunoassay.
Results
In the induction of trophoblast differentiation from naive iPSCs, treatment with a FOXO1 inhibitor resulted in the enhanced expression of TE markers, CDX2 and HAND1, but conversely decreased the expression of ST markers, such as ERVW1 (Syncytin-1) and GCM1, and an EVT marker, HLA-G. The proportion of cells positive for an early TE marker TACSTD2 and negative for a late TE marker ENPEP was higher in FOXO1 inhibitor-treated cells than in non-treated cells. The expressions of ERVW1 (Syncytin-1), ERVFRD-1 (Syncytin-2), and other endogenous retrovirus (ERV)-associated genes that have been reported to be expressed in trophoblasts were suppressed in the cells obtained by differentiating the TE cells treated with FOXO1 inhibitor. Conclusions: Treatment with a FOXO1 inhibitor during TE induction from naive iPSCs promotes early TE differentiation but hinders the progression of differentiation into ST and EVT. The suppression of ERV-associated genes may be involved in this process.