Figure 1.

A model illustrating the importance of epigenetic regulation of noncoding PCH in mediating the balance between pluripotency and priming for differentiation. The pluripotent transcription factors NANOG and SALL1 co-bind to PCH to maintain an open heterochromatin state in ESCs that is characterized by elevated PCH transcript levels and lower levels of repressive marks including H3K9me3. As Nanog levels decrease upon transition to EpiSCs, PCH loci adopt an inaccessible and transcriptionally repressed epigenetic state, triggering the formation of constitutive heterochromatic and potentially repressive nuclear compartments.