Expression data from C2C12 murine myoblast cells infected with an inducible Msx1-ER fusion protein

The spatial and temporal control of gene expression during development requires the concerted actions of sequence-specific transcriptional regulators and epigenetic chromatin modifiers, which are thought to function within precise nuclear compartments. However, how these activities are coordinated within the dynamic context of the nuclear environment is still largely unresolved. Here we show that transcriptional repression by the Msx1 homeoprotein coordinates recruitment of Polycomb to genomic targets with localization to the nuclear periphery. Using genome-wide ChIP-Seq analyses to identify genomic binding sites for Msx1, we find that repressed target genes are enriched at the nuclear periphery in myoblast cells. We further show that the interaction of Msx1 with the Polycomb repressive complex PRC2 is required for transcriptional repression and regulation of myoblast differentiation, and promotes increased tri-methylation of lysine 27 on histone H3 (H3K27me3) at Msx1 target genes. Furthermore, Msx1 genomic binding promotes the dynamic spatial redistribution of the H3K27me3 repressive mark to the nuclear periphery in developing embryos in vivo. Thus, our findings suggest a hitherto unappreciated spatial coordination of transcription factor binding, Polycomb recruitment, and subnuclear localization in regulation of developmentgene expression programs.

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