First published online May 23, 2006
Development 133, 1203e (2006)
© The Company of Biologists Limited
PcGs get complex with mammalian Hox genes
Polycomb group (PcG) proteins repress homeotic (Hox) gene expression in
specific embryonic regions of mammals but the molecular mechanism of this
control is poorly understood. Fujimura and co-workers now report that, in
mouse embryos, class 2 PcG components (which bind to DNA regulatory sequences)
form complexes of different compositions to control spatial Hoxb8
expression (shown in blue). The researchers on p.
2371 reveal that PcG
protein binding and histone modifications around Hoxb8 are different
in tissues that do and do not express Hoxb8. In particular, they show
that the binding near Hoxb8 of a class 2 PcG complex that contains
the E3 ubiquitin ligase Rnf2, together with trimethylation of histone H3,
which marks inactive chromatin, correlates with transcriptional silencing of
Hoxb8. Genetic impairment of Suz12 (a class 1 PcG protein that
trimethylates histone tails) and of Rnf2 produces Hox gene derepression. Thus,
interactions between class 1 and class 2 PcG proteins maintain repression of
Hox genes outside their expression domains in mice, as in
Drosophila.
Related articles in Development:
- Distinct roles of Polycomb group gene products in transcriptionally repressed and active domains of Hoxb8
- Yu-ichi Fujimura, Kyo-ichi Isono, Miguel Vidal, Mitsuhiro Endoh, Hiroshi Kajita, Yoko Mizutani-Koseki, Yoshihiro Takihara, Maarten van Lohuizen, Arie Otte, Thomas Jenuwein, Jacqueline Deschamps, and Haruhiko Koseki
Development 2006 133: 2371-2381.
[Abstract]
[Full Text]
