Transcription factories: gene expression in unions?

Key Points The fundamental process of gene transcription can be reconstituted in vitro , but an understanding of how it operates and how it is regulated in vivo is lacking. One hypothesis suggests that, rather than RNA polymerases being recruited to the promoters of active genes, it is the gene loci...

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Veröffentlicht in:Nature reviews. Genetics 2009-07, Vol.10 (7), p.457-466
Hauptverfasser: Bickmore, Wendy A, Sutherland, Heidi
Format: Artikel
Sprache:eng
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Zusammenfassung:Key Points The fundamental process of gene transcription can be reconstituted in vitro , but an understanding of how it operates and how it is regulated in vivo is lacking. One hypothesis suggests that, rather than RNA polymerases being recruited to the promoters of active genes, it is the gene loci that must move to sites in the nucleus — termed transcription factories — where RNA polymerase II is anchored. Cell biology approaches have driven the transcription factory model. Active genes can be seen in close spatial proximity to one another in the nucleus, at sites coincident with high concentrations of the active elongating form of RNA polymerase II. Molecular chromatin conformation capture (3C)-based approaches also indicate a spatial clustering of active genes in the cell nucleus. An unanswered question is whether transcription factories are a cause or a consequence of gene expression. The transcription factory model has implications for the evolution of gene order along and between chromosomes, and for the generation of chromosome translocations. Foci of transcriptional activity are observed in eukaryotic nuclei and have been called transcription factories. However, many uncertainties about their function and identity remain and the evidence can be conflicting, as the authors discuss in this Review. Transcription is a fundamental step in gene expression, yet it remains poorly understood at a cellular level. Visualization of transcription sites and active genes has led to the suggestion that transcription occurs at discrete sites in the nucleus, termed transcription factories, where multiple active RNA polymerases are concentrated and anchored to a nuclear substructure. However, this concept is not universally accepted. This Review discusses the experimental evidence in support of the transcription factory model and the evidence that argues against such a spatially structured view of transcription. The transcription factory model has implications for the regulation of transcription initiation and elongation, for the organization of genes in the genome, for the co-regulation of genes and for genome instability.
ISSN:1471-0056
1471-0064
DOI:10.1038/nrg2592