First published online February 23, 2005
Journal of Cell Science 118, 505e (2005)
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Transcription before decondensation
It is generally accepted that for genes to become transcriptionally active the chromatin surrounding them has to decondense. However, this proposal is supported only by data from systems in which foreign promoters drive gene expression. Now, Peter Shaw and co-workers describe the induction of large-scale chromatin decondensation in two transgenic wheat loci under the control of their normal, developmentally regulated promoter (see p. 1021). The storage protein glutenin is expressed in the endosperm of the developing wheat grain. The authors use fluorescence in-situ hybridization and confocal imaging to examine two transgenic wheat lines containing about 20 or 50 copies of the genes encoding two glutenin subunits together with their promoters. Each transgene locus is visible as one or two condensed foci in tissues where glutenin is not transcribed but decondenses extensively into many foci upon activation of transcription. Unexpectedly, the authors find that the initiation of transcription can precede extensive decondensation but not vice-versa. Future experiments should determine the DNA and/or chromatin modifications that underlie these changes in higher chromatin order.
Related articles in JCS:
- Large-scale chromatin decondensation induced in a developmentally activated transgene locus
- Eva Wegel, Ruben H. Vallejos, Paul Christou, Eva Stöger, and Peter Shaw
JCS 2005 118: 1021-1031.
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