Molecular Determinants For Polycomb Group Protein Yy1 Control Of Hematopoietic Stem Cell Quiescence

Hematopoietic stem cells (HSCs) are undifferentiated, long-lived cells that give rise to lineage-specific progenitors and retain their stem cell identity by undergoing self-renewal. Adult HSCs can remain in a quiescent state for a prolonged time, and quiescence is a fundamental characteristic of adult bone marrow-resident HSCs. A precisely regulated cell cycle is required for HSC-mediated generation of mature hematopoietic cells, while preventing stem cell exhaustion. Yin Yang 1 (YY1) is a ubiquitous transcription factor and mammalian Polycomb Group Protein (PcG) with important functions to regulate embryonic development, lineage differentiation and cell proliferation. YY1 mediates stable PcG-dependent transcriptional repression via recruitment of PcG proteins that catalyze histone modifications. Many questions remain unanswered regarding how cell-and tissue-specific regulation is achieved by PcG proteins …