BRG1 GovernsNanogTranscription in Early Mouse Embryos and Embryonic Stem Cells via Antagonism of Histone H3 Lysine 9/14 Acetylation
During mouse preimplantation development, the generation of the inner cell mass (ICM) and trophoblast lineages comprises upregulation ofNanogexpression in the ICM and its silencing in the trophoblast. However, the underlying epigenetic mechanisms that differentially regulateNanogin the first cell lineages are poorly understood. Here, we report that BRG1 (Brahma-related gene 1) cooperates with histone deacetylase 1 (HDAC1) to regulateNanogexpression. BRG1 depletion in preimplantation embryos andCdx2-inducible embryonic stem cells (ESCs) revealed that BRG1 is necessary forNanogsilencing in the trophoblast lineage. Conversely, in undifferentiated ESCs, loss of BRG1 augmentedNanogexpression. Analysis of histone H3 within theNanogproximal enhancer revealed that H3 lysine 9/14 (H3K9/14) acetylation increased in BRG1-depleted embryos and ESCs. Biochemical studies demonstrated that HDAC1 was present in BRG1-BAF155 complexes and BRG1-HDAC1 interactions were enriched in the trophoblast lineage. HDAC1 inhibition triggered an increase in H3K9/14 acetylation and a corresponding rise inNanogmRNA and protein, phenocopying BRG1 knockdown embryos and ESCs. Lastly, nucleosome-mapping experiments revealed that BRG1 is indispensable for nucleosome remodeling at theNanogenhancer during trophoblast development. In summary, our data suggest that BRG1 governsNanogexpression via a dual mechanism involving histone deacetylation and nucleosome remodeling.