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First published online 5 February 2008
doi: 10.1242/jcs.023234

This Article Figures Only Full Text Full Text (PDF) All Versions of this Article: jcs.023234v1 121/5/571    most recent Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Related articles in JCS Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Google Scholar Articles by Morey, C. Articles by Bickmore, W. A. PubMed PubMed Citation Articles by Morey, C. Articles by Bickmore, W. A.

Ectopic nuclear reorganisation driven by a Hoxb1 transgene transposed into Hoxd

¹ MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, Edinburgh University, Crewe Road, Edinburgh EH4 2XU, UK
² Institut National de la Transfusion Sanguine (INTS), 6 rue Alexandre Cabanel, 75015 Paris, France
³ Laboratory of Genetics and Development, Institut de Recherches Cliniques de Montréal (IRCM), Université de Montréal, 110 avenue des Pins Ouest, H2W 1R7, Montréal, Quebec, Canada
⁴ Department of Zoology and Animal Biology and National Research Centre `Frontiers in Genetics', University of Geneva, Sciences III, and School of Life Science, Ecole Polytechnique Federale, Lausanne, Switzerland

^* Author for correspondence (e-mail: W.Bickmore{at}hgu.mrc.ac.uk)

Accepted 19 November 2007

The extent to which the nuclear organisation of a gene impacts on its ability to be expressed, or whether nuclear organisation merely reflects gene expression states, remains an important but unresolved issue. A model system that has been instrumental in investigating this question utilises the murine Hox gene clusters encoding homeobox-containing proteins. Nuclear reorganisation and chromatin decondensation, initiated towards the 3' end of the clusters, accompanies activation of Hox genes in both differentiation and development, and might be linked to mechanisms underlying colinearity. To investigate this, and to delineate the cis-acting elements involved, here we analyse the nuclear behaviour of a 3' Hoxb1 transgene transposed to the 5' end of the Hoxd cluster. We show that this transgene contains the cis-acting elements sufficient to initiate ectopic local nuclear reorganisation and chromatin decondensation and to break Hoxd colinearity in the primitive streak region of the early embryo. Significantly, in rhombomere 4, the transgene is able to induce attenuated nuclear reorganisation and decondensation of Hoxd even though there is no detectable expression of the transgene at this site. This shows that reorganisation of chromosome territories and chromatin decondensation can be uncoupled from transcription itself and suggests that they can therefore operate upstream of gene expression.

Key words: Chromatin condensation, Chromosome territory, Colinearity, Hox, Nuclear organisation

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Nuclear reorganisation: no expression necessary

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				C. Morey, N. R. DaSilva, M. Kmita, D. Duboule, and W. A. Bickmore Ectopic nuclear reorganisation driven by a Hoxb1 transgene transposed into Hoxd Development, March 15, 2008; 135(6): e1 - e1. [Full Text]