Nuclear distribution of transcription factors in relation to sites of transcription and RNA polymerase II

Abstract

We have investigated the spatial relationship between sites containing newly synthesized RNA and domains containing proteins involved in transcription, such as RNA polymerase II and the transcription factors TFIIH, Oct1, BRG1, E2F-1 and glucocorticoid receptors, using dual immunofluorescence labelling followed by confocal microscopy on cultured cells. As expected, a high degree of colocalisation between the RNA polymerase II and sites containing newly synthesised RNA was observed. Like the newly synthesised RNA and the RNA polymerase II, we found that all the transcription factors that we studied are distributed more or less homogeneously throughout the nucleoplasm, occupying numerous small domains. In addition to these small domains, TFIIH was found concentrated in coiled bodies and Oct1 in a single large domain of about 1.5 microm in 30% of the cells in an asynchronous HeLa cell culture. Remarkably, we found little or no relationship between the spatial distribution of the glucocorticoid receptor, Oct1 and E2F-1 on the one hand and RNA polymerase II and transcription sites on the other hand. In contrast, a significant but incomplete overlap was observed between the spatial distributions of transcription sites and BRG1 and TFIIH. These results indicate that many of the transcription factor-rich nuclear domains are not actively involved in transcription. They may represent incomplete transcription initiation complexes, inhibitory complexes, or storage sites.

Correction: Transcription and Chromatin Organization of a Housekeeping Gene Cluster Containing an Integrated β-Globin Locus Control Region

“…We then analyzed whether the LCR influenced the association of 8C3/C4 with foci containing the transcriptionally active (serine2-phosphorylated) form of RNAP II, which marks transcription factories as determined after co-localization with sites of Br-UTP incorporation [29,42]. Using cryo-immuno-FISH to simultaneously visualize the elongating isoform of RNAP II and 8C3/C4, we found that 51% of the WT alleles associated with RNAP II foci, as scored visually, meaning that signals overlapped or touched (without background pixels in between; Figure 4A).…”

Spatio-temporal dynamics of nuclear CREB1: what does it mean?

“…Our understanding is not yet clear about CREB1 spatio-temporal distribution and how CREB1 interacts with the chromatin and interchromatin elements of the pinealocyte nuclei. Dynamic spatial distribution of transcription factors is considered a feature of the highly plastic and compartmentalized structure of a cell nucleus, and it is expected to impact in nuclear functions (37)(38)(39)(40)(41)(42)(43)(44).…”