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Promoter elements associated with RNA Pol II stalling in the Drosophila embryo.

ABSTRACT: RNA Polymerase II (Pol II) is bound to the promoter regions of many or most developmental control genes before their activation during Drosophila embryogenesis. It has been suggested that Pol II stalling is used to produce dynamic and rapid responses of developmental patterning genes to transient cues such as extracellular signaling molecules. Here, we present a combined computational and experimental analysis of stalled promoters to determine how they come to bind Pol II in the early Drosophila embryo. At least one-fourth of the stalled promoters contain a shared sequence motif, the "pause button" (PB): KCGRWCG. The PB motif is sometimes located in the position of the DPE, and over one-fifth of the stalled promoters contain the following arrangement of core elements: GAGA, Inr, PB, and/or DPE. This arrangement was used to identify additional stalled promoters in the Drosophila genome, and permanganate footprint assays were used to confirm that the segmentation gene engrailed contains paused Pol II as seen for heat-shock genes. We discuss different models for Pol II binding and gene activation in the early embryo.

SUBMITTER: Hendrix DA

PROVIDER: S-EPMC2396556 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Global analysis of short RNAs reveals widespread promoter-proximal stalling and arrest of Pol II in Drosophila.

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NELF-mediated stalling of Pol II can enhance gene expression by blocking promoter-proximal nucleosome assembly.

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NELF Regulates a Promoter-Proximal Step Distinct from RNA Pol II Pause-Release.

Project description:RNA polymerase II (RNA Pol II) is generally paused at promoter-proximal regions in most metazoans, and based on in vitro studies, this function has been attributed to the negative elongation factor (NELF). Here, we show that upon rapid depletion of NELF, RNA Pol II fails to be released into gene bodies, stopping instead around the +1 nucleosomal dyad-associated region. The transition to the 2nd pause region is independent of positive transcription elongation factor P-TEFb. During the heat shock response, RNA Pol II is rapidly released from pausing at heat shock-induced genes, while most genes are paused and transcriptionally downregulated. Both of these aspects of the heat shock response remain intact upon NELF loss. We find that NELF depletion results in global loss of cap-binding complex from chromatin without global reduction of nascent transcript 5' cap stability. Thus, our studies implicate NELF functioning in early elongation complexes distinct from RNA Pol II pause-release.

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Global Analysis of Short RNAs Reveals Widespread Promoter-Proximal Stalling and Arrest of Pol II

Project description:We developed a novel approach to isolate and characterize, at nucleotide-level resolution, the RNAs derived from RNA polymerase II (Pol II) in early elongation complexes. We find that high numbers of these short RNAs are not correlated with gene expression but instead are indicative of promoter-proximally stalled polymerase. High amounts of these short RNAs are generated from more than one third of all genes, indicating that Pol II stalls in the promoter-proximal region on global scale. We also find that the nucleotide composition of the initially transcribed sequence plays an important role in promoting transcriptional stalling and that early elongation complexes are highly susceptible to backtracking and arrest. Global analysis of RNAs produced by promoter-proximal Pol II.

2009-12-11 | E-GEOD-18643 | biostudies-arrayexpress

The polycomb group mutant esc leads to augmented levels of paused Pol II in the Drosophila embryo.

Project description:Many developmental control genes contain paused RNA polymerase II (Pol II) and are thereby "poised" for rapid and synchronous activation in the early Drosophila embryo. Evidence is presented that Polycomb group (PcG) repressors can influence paused Pol II. ChIP-Seq and GRO-Seq assays were used to determine the genome-wide distributions of Pol II, H3K27me3, and H3K4me3 in extra sex combs (esc) mutant embryos. ESC is a key component of the Polycomb repressive complex 2 (PRC2), which mediates H3K27me3 modification. Enhanced Pol II occupancy is observed for thousands of genes in esc mutant embryos, including genes not directly regulated by PRC2. Thus, it would appear that silent genes lacking promoter-associated paused Pol II in wild-type embryos are converted into "poised" genes with paused Pol II in esc mutants. We suggest that this conversion of silent genes into poised genes might render differentiated cell types susceptible to switches in identity in PcG mutants.

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