The Rtf1 Component of the Paf1 Transcriptional Elongation Complex Is Required for Ubiquitination of Histone H2B

Abstract Diffuse intrinsic pontine glioma (DIPG) is highly aggressive brain stem tumor and needed to develop novel therapeutic agents for the treatment. The super elongation complex (SEC) is essential for transcription elongation through release of RNA polymerase II (Pol II). We found that AFF4, a scaffold protein of the SEC, is required for the growth of H3K27M-mutant DIPG cells. In addition, the small molecule SEC inhibitor, KL-1, increased promoter-proximal pausing of Pol II, and reduced transcription elongation, resulting in down-regulate cell cycle, transcription and DNA repair genes. KL-1 treatment decreased cell growth and increased apoptosis in H3K27M-mutant DIPG cells, and prolonged animal survival in our human H3K27M-mutant DIPG xenograft model. Our results demonstrate that the SEC disruption by KL-1 is a novel therapeutic strategy for H3K27M-mutant DIPG.

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Regulation of P-TEFb Elongation Complex Activity by CDK9 Acetylation

Molecular and Cellular Biology ◽

10.1128/mcb.00857-06 ◽

2007 ◽

Vol 27 (13) ◽

pp. 4641-4651 ◽

Cited By ~ 40

Author(s):

Junjiang Fu ◽

Ho-Geun Yoon ◽

Jun Qin ◽

Jiemin Wong

Keyword(s):

Rna Polymerase Ii ◽

Elongation Factor ◽

Transcriptional Elongation ◽

Elongation Complex ◽

Complex Activity ◽

Interacting Protein ◽

Pol Ii ◽

Carboxy Terminal

ABSTRACT P-TEFb, comprised of CDK9 and a cyclin T subunit, is a global transcriptional elongation factor important for most RNA polymerase II (pol II) transcription. P-TEFb facilitates transcription elongation in part by phosphorylating Ser2 of the heptapeptide repeat of the carboxy-terminal domain (CTD) of the largest subunit of pol II. Previous studies have shown that P-TEFb is subjected to negative regulation by forming an inactive complex with 7SK small RNA and HEXIM1. In an effort to investigate the molecular mechanism by which corepressor N-CoR mediates transcription repression, we identified HEXIM1 as an N-CoR-interacting protein. This finding led us to test whether the P-TEFb complex is regulated by acetylation. We demonstrate that CDK9 is an acetylated protein in cells and can be acetylated by p300 in vitro. Through both in vitro and in vivo assays, we identified lysine 44 of CDK9 as a major acetylation site. We present evidence that CDK9 is regulated by N-CoR and its associated HDAC3 and that acetylation of CDK9 affects its ability to phosphorylate the CTD of pol II. These results suggest that acetylation of CDK9 is an important posttranslational modification that is involved in regulating P-TEFb transcriptional elongation function.

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Coordinate activities of BRD4 and CDK9 in the transcriptional elongation complex are required for TGFβ-induced Nox4 expression and myofibroblast transdifferentiation

Cell Death and Disease ◽

10.1038/cddis.2016.434 ◽

2017 ◽

Vol 8 (2) ◽

pp. e2606-e2606 ◽

Cited By ~ 16

Author(s):

Talha Ijaz ◽

Mohammad Jamaluddin ◽

Yingxin Zhao ◽

Yueqing Zhang ◽

Jayson Jay ◽

...

Keyword(s):

Transcriptional Elongation ◽

Elongation Complex

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Promoter-specific changes in initiation, elongation and homeostasis of histone H3 acetylation during CBP/p300 inhibition

eLife ◽

10.7554/elife.63512 ◽

2021 ◽

Vol 10 ◽

Author(s):

Emily Hsu ◽

Nathan R Zemke ◽

Arnold J Berk

Keyword(s):

Rna Polymerase Ii ◽

Control Point ◽

Histone H3 ◽

Airway Epithelial Cells ◽

Proximal Region ◽

Transferase Activity ◽

Transcriptional Elongation ◽

Elongation Complex ◽

Histone H3 Acetylation ◽

H3 Acetylation

Regulation of RNA Polymerase II (Pol2) elongation in the promoter proximal region is an important and ubiquitous control point for gene expression in metazoans. We report that transcription of the adenovirus 5 E4 region is regulated during the release of paused Pol2 into productive elongation by recruitment of the super elongation complex (SEC), dependent on promoter H3K18/27 acetylation by CBP/p300. We also establish that this is a general transcriptional regulatory mechanism that applies to ~6% of expressed protein-coding genes in primary human airway epithelial cells. We observed that a homeostatic mechanism maintains promoter, but not enhancer H3K18/27ac in response to extensive inhibition of CBP/p300 acetyl transferase activity by the highly specific small molecule inhibitor A-485. Further, our results suggest a function for BRD4 association at enhancers in regulating paused Pol2 release at nearby promoters. Taken together, our results uncover processes regulating transcriptional elongation by promoter region histone H3 acetylation and homeostatic maintenance of promoter, but not enhancer, H3K18/27ac in response to inhibition of CBP/p300 acetyl transferase activity.

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Histone Monoubiquitination in Chromatin Remodelling: Focus on the Histone H2B Interactome and Cancer

Cancers ◽

10.3390/cancers12113462 ◽

2020 ◽

Vol 12 (11) ◽

pp. 3462

Author(s):

Deborah J. Marsh ◽

Yue Ma ◽

Kristie-Ann Dickson

Keyword(s):

Dna Damage ◽

Rna Polymerase Ii ◽

Target Genes ◽

Chromatin Remodelling ◽

Extensive Literature ◽

Transcriptional Elongation ◽

Post Translational Modification ◽

Coding Region ◽

Histone H2b ◽

Related Proteins

Chromatin remodelling is a major mechanism by which cells control fundamental processes including gene expression, the DNA damage response (DDR) and ensuring the genomic plasticity required by stem cells to enable differentiation. The post-translational modification of histone H2B resulting in addition of a single ubiquitin, in humans at lysine 120 (K120; H2Bub1) and in yeast at K123, has key roles in transcriptional elongation associated with the RNA polymerase II-associated factor 1 complex (PAF1C) and in the DDR. H2Bub1 itself has been described as having tumour suppressive roles and a number of cancer-related proteins and/or complexes are recognised as part of the H2Bub1 interactome. These include the RING finger E3 ubiquitin ligases RNF20, RNF40 and BRCA1, the guardian of the genome p53, the PAF1C member CDC73, subunits of the switch/sucrose non-fermenting (SWI/SNF) chromatin remodelling complex and histone methyltransferase complexes DOT1L and COMPASS, as well as multiple deubiquitinases including USP22 and USP44. While globally depleted in many primary human malignancies, including breast, lung and colorectal cancer, H2Bub1 is selectively enriched at the coding region of certain highly expressed genes, including at p53 target genes in response to DNA damage, functioning to exercise transcriptional control of these loci. This review draws together extensive literature to cement a significant role for H2Bub1 in a range of human malignancies and discusses the interplay between key cancer-related proteins and H2Bub1-associated chromatin remodelling.

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Transcriptional Elongation Control of Hepatitis B Virus Covalently Closed Circular DNA Transcription by Super Elongation Complex and BRD4

Molecular and Cellular Biology ◽

10.1128/mcb.00040-17 ◽

2017 ◽

Vol 37 (19) ◽

Cited By ~ 8

Author(s):

Joel Celio Francisco ◽

Qian Dai ◽

Zhuojuan Luo ◽

Yan Wang ◽

Roxanne Hui-Heng Chong ◽

...

Keyword(s):

Hepatitis B Virus ◽

Hepatitis B ◽

Hbv Infection ◽

Intermediate Step ◽

Hbv Reactivation ◽

Transcriptional Elongation ◽

Elongation Complex ◽

Super Elongation Complex ◽

Chronic Hepatitis B Virus ◽

B Virus

ABSTRACT Chronic hepatitis B virus (HBV) infection can lead to liver cirrhosis and hepatocellular carcinoma. HBV reactivation during or after chemotherapy is a potentially fatal complication for cancer patients with chronic HBV infection. Transcription of HBV is a critical intermediate step of the HBV life cycle. However, factors controlling HBV transcription remain largely unknown. Here, we found that different P-TEFb complexes are involved in the transcription of the HBV viral genome. Both BRD4 and the super elongation complex (SEC) bind to the HBV genome. The treatment of bromodomain inhibitor JQ1 stimulates HBV transcription and increases the occupancy of BRD4 on the HBV genome, suggesting the bromodomain-independent recruitment of BRD4 to the HBV genome. JQ1 also leads to the increased binding of SEC to the HBV genome, and SEC is required for JQ1-induced HBV transcription. These findings reveal a novel mechanism by which the HBV genome hijacks the host P-TEFb-containing complexes to promote its own transcription. Our findings also point out an important clinical implication, that is, the potential risk of HBV reactivation during therapy with a BRD4 inhibitor, such as JQ1 or its analogues, which are a potential treatment for acute myeloid leukemia.

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Promoter-specific changes in initiation, elongation and homeostasis of histone H3 acetylation during CBP/p300 Inhibition

10.1101/2020.09.26.315002 ◽

2020 ◽

Author(s):

E Hsu ◽

NR Zemke ◽

AJ Berk

Keyword(s):

Rna Polymerase Ii ◽

Control Point ◽

Histone H3 ◽

Airway Epithelial Cells ◽

Proximal Region ◽

Transferase Activity ◽

Transcriptional Elongation ◽

Elongation Complex ◽

Histone H3 Acetylation ◽

H3 Acetylation

SummaryRegulation of RNA Polymerase II (Pol2) elongation in the promoter proximal region is an important and ubiquitous control point for gene expression in metazoan cells. We report that transcription of the adenovirus 5 E4 region is regulated during the release of paused Pol2 into productive elongation by recruitment of the super elongation complex (SEC), dependent on promoter H3K18/27 acetylation by CBP/p300. We also establish that this is a general transcriptional regulatory mechanism for ∼6% of genes expressed with FPKM>1 in primary human airway epithelial cells. We observed that a homeostatic mechanism maintains promoter, but not enhancer H3K18/27ac in response to extensive inhibition of CBP/p300 acetyl transferase activity by the highly specific small molecule inhibitor A-485. Further, our results suggest a function for BRD4 association at enhancers in regulating paused Pol2 release at nearby promoters. Taken together, our results uncover processes regulating transcriptional elongation by promoter region histone H3 acetylation and homeostatic maintenance of promoter, but not enhancer, H3K18/27ac in response to inhibition of CBP/p300 acetyl transferase activity.

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Host cell factors stimulate HIV-1 transcription by antagonizing substrate-binding function of Siah1 ubiquitin ligase to stabilize transcription elongation factor ELL2

Nucleic Acids Research ◽

10.1093/nar/gkaa461 ◽

2020 ◽

Cited By ~ 1

Author(s):

Jun Wu ◽

Yuhua Xue ◽

Xiang Gao ◽

Qiang Zhou

Keyword(s):

Host Cell ◽

Stress Responses ◽

Substrate Binding ◽

Elongation Factor ◽

Transcriptional Elongation ◽

Elongation Complex ◽

Binding Function ◽

Cellular Stress Responses ◽

Host Cell Factors ◽

Hiv 1

Abstract The Siah1 and Siah2 ubiquitin ligases are implicated in diverse biological processes ranging from cellular stress responses, signaling to transcriptional regulation. A key substrate of Siah1 is ELL2, which undergoes proteolysis upon polyubiquitination. ELL2 stimulates transcriptional elongation and is a subunit of the Super Elongation Complex (SEC) essential for HIV-1 transactivation. Previously, multiple transcriptional and post-translational mechanisms are reported to control Siah's expression and activity. Here we show that the activity of Siah1/2 can also be suppressed by host cell factor 1 (HCF1), and the hitherto poorly characterized HCF2, which themselves are not degraded but can bind and block the substrate-binding domain (SBD) of Siah1/2 to prevent their autoubiquitination and trans-ubiquitination of downstream targets including ELL2. This effect stabilizes ELL2 and enhances the ELL2-SEC formation for robust HIV-1 transactivation. Thus, our study not only identifies HCF1/2 as novel activators of HIV-1 transcription through inhibiting Siah1 to stabilize ELL2, but also reveals the SBD of Siah1/2 as a previously unrecognized new target for HCF1/2 to exert this inhibition.

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