title: Modulation of RNA polymerase assembly dynamics in transcriptional regulation.
abstract: The interaction of transcription factors with target genes is highly dynamic. Whether the dynamic nature of these interactions is merely an intrinsic property of transcription factors or serves a regulatory role is unknown. Here we have used single-cell fluorescence imaging combined with computational modeling and chromatin immunoprecipitation to analyze transcription complex dynamics in gene regulation during the cell cycle in living cells. We demonstrate a link between the dynamics of RNA polymerase I (RNA Pol I) assembly and transcriptional output. We show that transcriptional upregulation is accompanied by prolonged retention of RNA Pol I components at the promoter, resulting in longer promoter dwell time, and an increase in the steady-state population of assembling polymerase. As a consequence, polymerase assembly efficiency and, ultimately, the rate of entry into processive elongation are elevated. Our results show that regulation of rDNA transcription in vivo occurs via modulation of the efficiency of transcription complex subunit capture and assembly.
authors.affiliation: National Cancer Institute, Laboratory of Receptor Biology and Gene Expression, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: Stanislaw A
authors.initials: SA
authors.lastname: Gorski
authors.forename: Sara K
authors.initials: SK
authors.lastname: Snyder
authors.forename: Sam
authors.initials: S
authors.lastname: John
authors.forename: Ingrid
authors.initials: I
authors.lastname: Grummt
authors.forename: Tom
authors.initials: T
authors.lastname: Misteli
mesh_terms: D000818:Animals; D002453:Cell Cycle / Q000502:physiology; D002478:Cells, Cultured; D004275:DNA, Ribosomal / Q000378:metabolism; D036681:Fluorescence Recovery After Photobleaching; D005786:Gene Expression Regulation; D006801:Humans; D011401:Promoter Regions, Genetic; D021122:Protein Subunits / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012318:RNA Polymerase I / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D004275:DNA, Ribosomal; D021122:Protein Subunits; D012318:RNA Polymerase I