First published online February 20, 2008
Journal of Cell Science 121, 502e (2008)
© The Company of Biologists Limited
Nuclear reorganisation: no expression necessary
The activation of gene expression is intimately linked to nuclear organisation. In regions of the genome that are transcriptionally active, chromatin becomes decondensed and often loops out from its normal chromosome territory – but are these changes merely a result of gene activation, or can they promote transcription? On page 571, Wendy Bickmore and colleagues explore this question. The authors analyse nuclear organisation in transgenic mouse embryos in which the Hoxb1 gene, which is normally expressed early in development (E7.5), is transposed to the Hoxd cluster, adjacent to genes that are expressed later (E9.5). In the primitive streak of E7.5 embryos, the authors show, the Hoxb1 transgene loops out of its chromosome territory and becomes activated (just as the endogenous Hoxb1 does) and, in addition, the transgene promotes chromatin decondensation in adjacent areas of the Hoxd cluster. In rhombomere 4 of the developing hindbrain, the transgene promotes the looping of adjacent Hoxd areas, as well as chromatin decondensation. Importantly, however, this is not accompanied by gene expression. Thus, nuclear reorganisation can occur independently of transcription, indicating that it is not always a mere byproduct of gene activation.
Related articles in JCS:
- Ectopic nuclear reorganisation driven by a Hoxb1 transgene transposed into Hoxd
- Céline Morey, Nelly R. Da Silva, Marie Kmita, Denis Duboule, and Wendy A. Bickmore
JCS 2008 121: 571-577.
[Abstract]
[Full Text]
