Nuclear Factor Erythroid-derived 2 (Nfe2) Regulates JunD DNA-binding Activity via Acetylation: A NOVEL MECHANISM REGULATING TROPHOBLAST DIFFERENTIATION

Abstract

We recently demonstrated that the bZip transcription factor nuclear factor erythroid-derived 2 (Nfe2) represses protein acetylation and expression of the transcription factor glial cell missing 1 (Gcm1) in trophoblast cells, preventing excess syncytiotrophoblast formation and permitting normal placental vascularization and embryonic growth. However, the Gcm1 promoter lacks a Nfe2-binding site and hence the mechanisms linking Nfe2 and Gcm1 expression remained unknown. Here we show that Nfe2 represses JunD DNA-binding activity to the Gcm1 promoter during syncytiotrophoblast differentiation. Interventional studies using knockdown and knockin approaches show that enhanced JunD DNA-binding activity is required for increased expression of Gcm1 and syncytiotrophoblast formation as well as impaired placental vascularization and reduced growth of Nfe2(-/-) embryos. Induction of Gcm1 expression requires binding of JunD to the -1441 site within the Gcm1 promoter, which is distinct from the -1314 site previously shown to induce Gcm1 expression by other bZip transcription factors. Nfe2 modulates JunD binding to the Gcm1 promoter via acetylation, as reducing JunD acetylation using the histone acetyltransferase inhibitor curcumin reverses the increased JunD DNA-binding activity observed in the absence of Nfe2. This identifies a novel mechanism through which bZip transcription factors interact. Within the placenta this interaction regulates Gcm1 expression, syncytiotrophoblast formation, placental vascularization, and embryonic growth.