scholarly journals Interaction between P-TEFb and the C-Terminal Domain of RNA Polymerase II Activates Transcriptional Elongation from Sites Upstream or Downstream of Target Genes

2002 ◽  
Vol 22 (1) ◽  
pp. 321-331 ◽  
Author(s):  
Ran Taube ◽  
Xin Lin ◽  
Dan Irwin ◽  
Koh Fujinaga ◽  
B. Matija Peterlin
Keyword(s):  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Target Genes ◽  
Elongation Factor ◽  
Transcriptional Elongation ◽  
Cyclin T1 ◽  
Positive Transcription Elongation Factor ◽  
Terminal Domain ◽  
Activation Of Transcription

ABSTRACT Transcriptional elongation by RNA polymerase II (RNAPII) is regulated by the positive transcription elongation factor b (P-TEFb). P-TEFb is composed of Cdk9 and C-type cyclin T1 (CycT1), CycT2a, CycT2b, or CycK. The role of the C-terminal region of CycT1 and CycT2 remains unknown. In this report, we demonstrate that these sequences are essential for the activation of transcription by P-TEFb via DNA, i.e., when CycT1 is tethered upstream or downstream of promoters and coding sequences. A histidine-rich stretch, which is conserved between CycT1 and CycT2 in this region, bound the C-terminal domain of RNAPII. This binding was required for the subsequent expression of full-length transcripts from target genes. Thus, P-TEFb could mediate effects of enhancers on the elongation of transcription.

scholarly journals The Role of RNA Polymerase II Elongation Control in HIV-1 Gene Expression, Replication, and Latency

2011 ◽  
Vol 2011 ◽  
pp. 1-9 ◽  
Author(s):  
Kyle A. Nilson ◽  
David H. Price
Keyword(s):  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Elongation Factor ◽  
Health Concern ◽  
Pol Ii ◽  
Positive Transcription Elongation Factor ◽  
Elongation Control ◽  
Hiv 1 ◽  
Latent Phase

HIV-1 usurps the RNA polymerase II elongation control machinery to regulate the expression of its genome during lytic and latent viral stages. After integration into the host genome, the HIV promoter within the long terminal repeat (LTR) is subject to potent downregulation in a postinitiation step of transcription. Once produced, the viral protein Tat commandeers the positive transcription elongation factor, P-TEFb, and brings it to the engaged RNA polymerase II (Pol II), leading to the production of viral proteins and genomic RNA. HIV can also enter a latent phase during which factors that regulate Pol II elongation may play a role in keeping the virus silent. HIV, the causative agent of AIDS, is a worldwide health concern. It is hoped that knowledge of the mechanisms regulating the expression of the HIV genome will lead to treatments and ultimately a cure.

scholarly journals Runx1 Binds Positive Transcription Elongation Factor b and Represses Transcriptional Elongation by RNA Polymerase II: Possible Mechanism of CD4 Silencing

2005 ◽  
Vol 25 (24) ◽  
pp. 10675-10683 ◽  
Author(s):  
Huimin Jiang ◽  
Fan Zhang ◽  
Takeshi Kurosu ◽  
B. Matija Peterlin
Keyword(s):  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Chromatin Immunoprecipitation ◽  
T Cell Development ◽  
Elongation Factor ◽  
Transcriptional Elongation ◽  
Positive Transcription Elongation Factor ◽  
Transcription Elongation Factor ◽  
Inhibitory Domain

ABSTRACT Runx1 binds the silencer and represses CD4 transcription in immature thymocytes. In this study, we found that Runx1 inhibits P-TEFb, which contains CycT1, CycT2, or CycK and Cdk9 and stimulates transcriptional elongation by RNA polymerase II (RNAPII) in eukaryotic cells. Indeed, its inhibitory domain, spanning positions 371 to 411, not only bound CycT1 but was required for silencing CD4 transcription in vivo. Our chromatin immunoprecipitation assays revealed that Runx1 inhibits the elongation but not initiation of transcription and that RNAPII is engaged at the CD4 promoter but is unable to elongate in CD4− CD8+ thymoma cells. These results suggest that active repression by Runx1 occurs by blocking the elongation by RNAPII, which may contribute to CD4 silencing during T-cell development.

scholarly journals The Ability of Positive Transcription Elongation Factor b To Transactivate Human Immunodeficiency Virus Transcription Depends on a Functional Kinase Domain, Cyclin T1, and Tat

1998 ◽  
Vol 72 (9) ◽  
pp. 7154-7159 ◽  
Author(s):  
Koh Fujinaga ◽  
Thomas P. Cujec ◽  
Junmin Peng ◽  
Judit Garriga ◽  
David H. Price ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Elongation Factor ◽  
Response Element ◽  
Factor B ◽  
Cyclin T1 ◽  
Positive Transcription Elongation Factor ◽  
Transcription Elongation Factor ◽  
Immunodeficiency Virus

ABSTRACT By binding to the transactivation response element (TAR) RNA, the transcriptional transactivator (Tat) from the human immunodeficiency virus increases rates of elongation rather than initiation of viral transcription. Two cyclin-dependent serine/threonine kinases, CDK7 and CDK9, which phosphorylate the C-terminal domain of RNA polymerase II, have been implicated in Tat transactivation in vivo and in vitro. In this report, we demonstrate that CDK9, which is the kinase component of the positive transcription elongation factor b (P-TEFb) complex, can activate viral transcription when tethered to the heterologous Rev response element RNA via the regulator of expression of virion proteins (Rev). The kinase activity of CDK9 and cyclin T1 is essential for these effects. Moreover, P-TEFb binds to TAR only in the presence of Tat. We conclude that Tat–P-TEFb complexes bind to TAR, where CDK9 modifies RNA polymerase II for the efficient copying of the viral genome.

scholarly journals MAQ1 and 7SK RNA Interact with CDK9/Cyclin T Complexes in a Transcription-Dependent Manner

2003 ◽  
Vol 23 (14) ◽  
pp. 4859-4869 ◽  
Author(s):  
Annemieke A. Michels ◽  
Van Trung Nguyen ◽  
Alessandro Fraldi ◽  
Valérie Labas ◽  
Mia Edwards ◽  
...  
Keyword(s):  
Rna Polymerase Ii ◽  
Specific Interaction ◽  
Elongation Factor ◽  
Virus Genome ◽  
Transcriptional Elongation ◽  
Dependent Manner ◽  
Small Nuclear Rna ◽  
Cyclin T1 ◽  
Terminal Domain ◽  
Immunodeficiency Virus

ABSTRACT Positive transcription elongation factor b (P-TEFb) comprises a cyclin (T1 or T2) and a kinase, cyclin-dependent kinase 9 (CDK9), which phosphorylates the carboxyl-terminal domain of RNA polymerase II. P-TEFb is essential for transcriptional elongation in human cells. A highly specific interaction among cyclin T1, the viral protein Tat, and the transactivation response (TAR) element RNA determines the productive transcription of the human immunodeficiency virus genome. In growing HeLa cells, half of P-TEFb is kinase inactive and binds to the 7SK small nuclear RNA. We now report on a novel protein termed MAQ1 (for ménage à quatre) that is also present in this complex. Since 7SK RNA is required for MAQ1 to associate with P-TEFb, a structural role for 7SK RNA is proposed. Inhibition of transcription results in the release of both MAQ1 and 7SK RNA from P-TEFb. Thus, MAQ1 cooperates with 7SK RNA to form a novel type of CDK inhibitor. According to yeast two-hybrid analysis and immunoprecipitations from extracts of transfected cells, MAQ1 binds directly to the N-terminal cyclin homology region of cyclins T1 and T2. Since Tat also binds to this cyclin T1 N-terminal domain and since the association between 7SK RNA/MAQ1 and P-TEFb competes with the binding of Tat to cyclin T1, we speculate that the TAR RNA/Tat lentivirus system has evolved to subvert the cellular 7SK RNA/MAQ1 system.

scholarly journals HIF-1 Interacts with TRIM28 and DNA-PK to release paused RNA polymerase II and activate target gene transcription in response to hypoxia

2022 ◽  
Vol 13 (1) ◽  
Author(s):  
Yongkang Yang ◽  
Haiquan Lu ◽  
Chelsey Chen ◽  
Yajing Lyu ◽  
Robert N. Cole ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Gene Transcription ◽  
Target Genes ◽  
Large Subunit ◽  
Hypoxia Inducible Factor ◽  
Elongation Factor ◽  
Transcriptional Elongation ◽  
Pol Ii

AbstractHypoxia-inducible factor-1 (HIF-1) is a transcription factor that acts as a regulator of oxygen (O2) homeostasis in metazoan species by binding to hypoxia response elements (HREs) and activating the transcription of hundreds of genes in response to reduced O2 availability. RNA polymerase II (Pol II) initiates transcription of many HIF target genes under non-hypoxic conditions but pauses after approximately 30–60 nucleotides and requires HIF-1 binding for release. Here we report that in hypoxic breast cancer cells, HIF-1 recruits TRIM28 and DNA-dependent protein kinase (DNA-PK) to HREs to release paused Pol II. We show that HIF-1α and TRIM28 assemble the catalytically-active DNA-PK heterotrimer, which phosphorylates TRIM28 at serine-824, enabling recruitment of CDK9, which phosphorylates serine-2 of the Pol II large subunit C-terminal domain as well as the negative elongation factor to release paused Pol II, thereby stimulating productive transcriptional elongation. Our studies reveal a molecular mechanism by which HIF-1 stimulates gene transcription and reveal that the anticancer effects of drugs targeting DNA-PK in breast cancer may be due in part to their inhibition of HIF-dependent transcription.

Identification of rpo30, a vaccinia virus RNA polymerase gene with structural similarity to a eucaryotic transcription elongation factor

1990 ◽  
Vol 10 (10) ◽  
pp. 5433-5441
Author(s):  
B Y Ahn ◽  
P D Gershon ◽  
E V Jones ◽  
B Moss
Keyword(s):  
Rna Polymerase ◽  
Vaccinia Virus ◽  
Rna Polymerase Ii ◽  
Elongation Factor ◽  
Viral Rna ◽  
In Vitro Translation ◽  
Virus Protein ◽  
Transcriptional Elongation

Eucaryotic transcription factors that stimulate RNA polymerase II by increasing the efficiency of elongation of specifically or randomly initiated RNA chains have been isolated and characterized. We have identified a 30-kilodalton (kDa) vaccinia virus-encoded protein with apparent homology to SII, a 34-kDa mammalian transcriptional elongation factor. In addition to amino acid sequence similarities, both proteins contain C-terminal putative zinc finger domains. Identification of the gene, rpo30, encoding the vaccinia virus protein was achieved by using antibody to the purified viral RNA polymerase for immunoprecipitation of the in vitro translation products of in vivo-synthesized early mRNA selected by hybridization to cloned DNA fragments of the viral genome. Western immunoblot analysis using antiserum made to the vaccinia rpo30 protein expressed in bacteria indicated that the 30-kDa protein remains associated with highly purified viral RNA polymerase. Thus, the vaccinia virus protein, unlike its eucaryotic homolog, is an integral RNA polymerase subunit rather than a readily separable transcription factor. Further studies showed that the expression of rpo30 is regulated by dual early and later promoters.

scholarly journals JMJD5 couples with CDK9 to release the paused RNA polymerase II

2020 ◽  
Vol 117 (33) ◽  
pp. 19888-19895
Author(s):  
Haolin Liu ◽  
Srinivas Ramachandran ◽  
Nova Fong ◽  
Tzu Phang ◽  
Schuyler Lee ◽  
...  
Keyword(s):  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Elongation Factor ◽  
Pol Ii ◽  
Transcription Start Sites ◽  
Terminal Domain ◽  
Carboxyl Terminal Domain ◽  
Pol Ii Pausing ◽  
Carboxyl Terminal ◽  
Heptad Repeats

More than 30% of genes in higher eukaryotes are regulated by RNA polymerase II (Pol II) promoter proximal pausing. Pausing is released by the positive transcription elongation factor complex (P-TEFb). However, the exact mechanism by which this occurs and whether phosphorylation of the carboxyl-terminal domain of Pol II is involved in the process remains unknown. We previously reported that JMJD5 could generate tailless nucleosomes at position +1 from transcription start sites (TSS), thus perhaps enable progression of Pol II. Here we find that knockout of JMJD5 leads to accumulation of nucleosomes at position +1. Absence of JMJD5 also results in loss of or lowered transcription of a large number of genes. Interestingly, we found that phosphorylation, by CDK9, of Ser2 within two neighboring heptad repeats in the carboxyl-terminal domain of Pol II, together with phosphorylation of Ser5 within the second repeat, HR-Ser2p (1, 2)-Ser5p (2) for short, allows Pol II to bind JMJD5 via engagement of the N-terminal domain of JMJD5. We suggest that these events bring JMJD5 near the nucleosome at position +1, thus allowing JMJD5 to clip histones on this nucleosome, a phenomenon that may contribute to release of Pol II pausing.

scholarly journals Postrecruitment Regulation of RNA Polymerase II Directs Rapid Signaling Responses at the Promoters of Estrogen Target Genes

2008 ◽  
Vol 29 (5) ◽  
pp. 1123-1133 ◽  
Author(s):  
Miltiadis Kininis ◽  
Gary D. Isaacs ◽  
Leighton J. Core ◽  
Nasun Hah ◽  
W. Lee Kraus
Keyword(s):  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Target Genes ◽  
Elongation Factor ◽  
Estrogen Signaling ◽  
Gene Promoters ◽  
Pol Ii ◽  
Activator Proteins ◽  
Classical Models ◽  
Target Promoters

ABSTRACT Under classical models for signal-dependent transcription in eukaryotes, DNA-binding activator proteins regulate the recruitment of RNA polymerase II (Pol II) to a set of target promoters. However, recent studies, as well as our results herein, show that Pol II is widely distributed (i.e., “preloaded”) at the promoters of many genes prior to specific signaling events. How Pol II recruitment and Pol II preloading fit within a unified model of gene regulation is unclear. In addition, the mechanisms through which cellular signals activate preloaded Pol II across mammalian genomes remain largely unknown. We show here that the predominant genomic outcome of estrogen signaling is the postrecruitment regulation of Pol II activity at target gene promoters, likely through specific changes in Pol II phosphorylation rather than through recruitment of Pol II to the promoters. Furthermore, we show that negative elongation factor binds to estrogen target promoters in conjunction with preloaded Pol II and represses gene expression until the appropriate signal is received. Finally, our studies reveal that the estrogen-dependent activation of preloaded Pol II facilitates rapid gene regulatory responses which play important physiological roles in regulating estrogen signaling itself. Our results reveal a broad use of postrecruitment Pol II regulation by the estrogen signaling pathway, a mode of regulation that is likely to apply to a wide variety of signal-regulated pathways.

Iron Chelator ICL670 Inhibits HIV-1 Transcription.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 3863-3863
Author(s):  
Zufan Debebe ◽  
Tatyana Ammosova ◽  
Hanspeter Nick ◽  
Xiaomei Niu ◽  
Marina Jerebtsova ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Protein Level ◽  
Iron Chelator ◽  
Iron Chelators ◽  
Cyclin T1 ◽  
Terminal Domain ◽  
Cycle Dependent ◽  
Hiv 1

Abstract HIV-1 replication is induced by the excess of iron and iron chelation by desferrioxamine (DFO) inhibits viral replication in HIV-1 infected CEM T cells [1]. Treatment of cells with DFO or 2-hydroxy-1-naphthylaldehyde isonicotinoyl hydrazone inhibits expression of proteins that regulate cell-cycle progression, including cycle-dependent kinase 2 (CDK2) [2]. HIV-1 transcription is activated by Tat protein, which recruits transcriptional co-activators to the HIV-1 promoter. Elongation of HIV-1 transcription is mediated by the interaction of HIV Tat with host cell cycle-dependent kinase 9 (CDK9)/cyclin T1, which phosphorylates the C-terminal domain of RNA polymerase II. Our recent studies showed that CDK2 participates in HIV-1 transcription by phosphorylating Tat [3]. Thus inhibition of CDK2 by iron chelators might present a new approach to inhibit HIV-1 transcription. We evaluated the effect of a clinically approved orally effective iron chelator, 4-[3,5-bis-(hydroxyphenyl) -1,2,4-triazol-1-yl]-benzoic acid (ICL670 or deferasirox) on HIV-1 transcription. ICL670 inhibited Tat-induced HIV-1 transcription in CEM, 293T and HeLa cells at concentrations that did not induce cytotoxicity. The chelator decreased cellular activity of CDK2 but not its protein level and reduced HIV-1 Tat phosphorylation by CDK2. ICL670 did not decrease CDK9 protein level but significantly reduced association of CDK9 with cyclin T1 and reduced phosphorylation of Ser-2 residues of RNA polymerase II C-terminal domain. In conclusion, our findings add to the evidence that iron chelators may inhibit HIV-1 transcription by deregulating CDK2 and Cdk9. Further consideration should be given to the evaluation of ICL670 for future anti-retroviral therapeutics and to the development of iron chelators specifically as anti-retroviral agents.

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