How ubiquitin silences genes

A novel mechanism of gene silencing that plays an unexpected role in inactivating the X chromosome is published in Developmental Cell this week. But the paper by Neil Brockdorff's group in London appears several weeks after an almost identical report from Yi Zhang and colleagues from the University of North Carolina at Chapel Hill in Nature.

Brockdorff, at the Medical Research Council's Clinical Sciences Centre, found that the presence of ubiquitylated histone H2A (uH2A) on the inactive X temporally correlated with the recruitment of Polycomb group (PcG) proteins belonging to Polycomb repressor complex 1 (PRC1), known to be involved in gene silencing, according to Mary Ann Osley, who is based at the Department of Molecular Genetics and Microbiology, University of New Mexico Health Sciences Center. This suggested that the events were coupled. The team also demonstrated a role for PRC1 Ring1B protein in genome-wide H2A ubiquitylation, and Ring1B and its ...