First published online February 9, 2007
Development 134, 504e (2007)
© The Company of Biologists Limited
Looping the loop with Hoxd
The relocalisation of gene loci outside chromosome territories and
chromatin decondensation are generally regarded as linked facets of gene
activation. Now, however, Wendy Bickmore and co-workers reveal that these
processes can occur separately during activation of the Hoxd gene cluster (see
p. 909). The
researchers analysed the nuclear organisation of the mouse Hoxd cluster in
differentiating embryonic stem (ES) cells and embryonic day 9.5 mouse embryos.
The Hoxd cluster, they report, like the Hoxb cluster, looped out from its
chromosome territory and unfolded after its activation in ES cells and in the
embryonic tailbud. But, in the limb bud (another site of Hoxd activation), the
chromatin unfolded without looping out. Furthermore, during ES cell
differentiation, parts of the Hoxd cluster looped out before their chromatin
visibly decondensed. Thus, although the chromosome remodelling mechanisms that
underlie Hox gene activation predate the duplication of mammalian Hox loci,
the exact mode of regulation of the Hoxd cluster depends on its developmental
context.
Related articles in Development:
- Nuclear reorganisation and chromatin decondensation are conserved, but distinct, mechanisms linked to Hox gene activation
- Céline Morey, Nelly R. Da Silva, Paul Perry, and Wendy A. Bickmore
Development 2007 134: 909-919.
[Abstract]
[Full Text]
