A group of proteins has been shown to help hold the reins on embryonic stem (ES) cell differentiation. ES cells are unique in their ability to self-renew while maintaining the ability to develop into virtually all adult cell types. Researchers report online in Nature that Polycomb group (PcG) proteins suppress the activation of many genes involved in cell developmental pathways.
Specifically, Rudolph Jaenisch and colleagues use a genome-wide location analysis in mouse ES cells to determine the genomic sites occupied by PcG protein complexes. They find that these complexes occupy the regulatory regions of a large number of target genes involved in cell differentiation - genes whose expression is repressed in undifferentiated ES cells. However, these genes are activated when the ES cells are induced to differentiate, and so it seems that the role of the PcG complexes is to keep their expression (and thus cell differentiation) in check in undifferentiated cells. When PcG complexes are disrupted in ES cells, expression of the target genes becomes activated and the cells tend to differentiate.
This research continues to build on our understanding of how ES cells are maintained and their potential as a therapeutic for many diseases.
udolph Jaenisch (Massaschusetts Institute of Technology, Cambridge, MA, USA)
Abstract available online.
(C) Nature press release.
Message posted by: Trevor M. D'Souza