Unique Trophoblast Chromatin Environment Mediated by the PcG Protein SFMBT2

Stem/progenitor cells are maintained by a chromatin environment, mediated in part by Polycomb group (PcG) proteins, that depresses differentiation. The trophoblast-specific PcG protein SFMBT2 is known to be required for maintenance of trophoblast progenitors. Rather than binding to trophoblast specific genes repressed in TSC, SFMBT2 is concentrated at chromocenters and regions rich in repetitive elements, specifically LINE sequences and major satellites, suggesting that it is involved in higher order organization of the trophoblast genome. It is also found enriched at a subset of ncRNAs. Comparison of ChIP-seq data sets for other chromatin proteins reveals several stereotypical distribution patterns, suggesting that SFMBT2 interacts with several different types of chromatin complexes specific to the trophoblast lineage.