TFEB controls syncytiotrophoblast formation and estrogen production in placenta

TFEB, a bHLH-leucine zipper transcription factor belonging to the MiT/TFE family, is a renowned global modulator of cell metabolism by regulating autophagy and lysosomal functions. Remarkably, loss of TFEB in mice causes embryonic lethality due to severe defects in placentation associated with aberrant vascularization and resulting hypoxia. However, the molecular mechanism underlying the described phenotype has yet to be elucidated. By integrating multi-omics approaches with functional assays, we uncover an unprecedented function for TFEB in promoting the formation of a functional syncytiotrophoblast in the placenta. Here, we showed that syncytiotrophoblast formation is marked by TFEB nuclear translocation and its association with the promoters of crucial placental genes, including fusogenic proteins (Syncytin-1 and Syncythin-2) and enzymes involved in the steroidogenic pathway, such as CYP19A1, the rate-limiting enzyme for the synthesis of 17β-Estradiol (E2). Conversely, the depletion of TFEB negatively impacts both the syncytial fusion and the endocrine properties of the syncytiotrophoblast, as demonstrated by a significant decrease in the secretion of placenta hormones and E2 production. Notably, the restoration of TFEB expression resets the syncytiotrophoblast identity. Finally, we identified reduced expression levels of TFEB and its target CYP19A1 in the placenta of pre-eclampsia women, suggesting that dysregulation of the TFEB-CYP19A1 axis might underlie the impairment of placental steroidogenesis described in pre-eclampsia. Our findings elect TFEB as a central controller of the metabolic properties of the placenta by orchestrating both the transcriptional program underlying trophoblast fusion and the acquisition of endocrine function, which are crucial for the bioenergetic requirements of embryonic development.