scholarly journals The HIV-1 Tat protein recruits a ubiquitin ligase to reorganize the 7SK snRNP for transcriptional activation

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Tyler B Faust ◽  
Yang Li ◽  
Curtis W Bacon ◽  
Gwendolyn M Jang ◽  
Amit Weiss ◽  
...  
Keyword(s):  
Rna Polymerase Ii ◽  
Ubiquitin Ligase ◽  
Transcriptional Activation ◽  
Transcriptional Activity ◽  
Kinase Inhibitor ◽  
Tat Protein ◽  
Viral Promoter ◽  
Rnap Ii ◽  
Elongation Control ◽  
Hiv 1

The HIV-1 Tat protein hijacks P-TEFb kinase to activate paused RNA polymerase II (RNAP II) at the viral promoter. Tat binds additional host factors, but it is unclear how they regulate RNAP II elongation. Here, we identify the cytoplasmic ubiquitin ligase UBE2O as critical for Tat transcriptional activity. Tat hijacks UBE2O to ubiquitinate the P-TEFb kinase inhibitor HEXIM1 of the 7SK snRNP, a fraction of which also resides in the cytoplasm bound to P-TEFb. HEXIM1 ubiquitination sequesters it in the cytoplasm and releases P-TEFb from the inhibitory 7SK complex. Free P-TEFb then becomes enriched in chromatin, a process that is also stimulated by treating cells with a CDK9 inhibitor. Finally, we demonstrate that UBE2O is critical for P-TEFb recruitment to the HIV-1 promoter. Together, the data support a unique model of elongation control where non-degradative ubiquitination of nuclear and cytoplasmic 7SK snRNP pools increases P-TEFb levels for transcriptional activation.

scholarly journals Author response: The HIV-1 Tat protein recruits a ubiquitin ligase to reorganize the 7SK snRNP for transcriptional activation

2018 ◽  
Author(s):  
Tyler B Faust ◽  
Yang Li ◽  
Curtis W Bacon ◽  
Gwendolyn M Jang ◽  
Amit Weiss ◽  
...  
Keyword(s):  
Ubiquitin Ligase ◽  
Transcriptional Activation ◽  
Author Response ◽  
Tat Protein ◽  
Hiv 1

scholarly journals Transcriptional Cofactor CA150 Regulates RNA Polymerase II Elongation in a TATA-Box-Dependent Manner

1999 ◽  
Vol 19 (7) ◽  
pp. 4719-4728 ◽  
Author(s):  
Carlos Suñé ◽  
Mariano A. Garcia-Blanco
Keyword(s):  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Transcriptional Activation ◽  
Tata Box ◽  
Dependent Manner ◽  
Functional Requirements ◽  
Tat Protein ◽  
Transcription Complexes ◽  
Hiv 1

ABSTRACT Tat protein strongly activates transcription from the human immunodeficiency virus type 1 (HIV-1) long terminal repeat (LTR) by enhancing the elongation efficiency of RNA polymerase II complexes. Tat-mediated transcriptional activation requires cellular cofactors and specific cis-acting elements within the HIV-1 promoter, among them a functional TATA box. Here, we have investigated the mechanism by which one of these cofactors, termed CA150, regulates HIV-1 transcription in vivo. We present a series of functional assays that demonstrate that the regulation of the HIV-1 LTR by CA150 has the same functional requirements as the activation by Tat. We found that CA150 affects elongation of transcription complexes assembled on the HIV-1 promoter in a TATA-box-dependent manner. We discuss the data in terms of the involvement of CA150 in the regulation of Tat-activated HIV-1 gene expression. In addition, we also provide evidence suggesting a role for CA150 in the regulation of cellular transcriptional processes.

scholarly journals Induction of TAK (Cyclin T1/P-TEFb) in Purified Resting CD4+ T Lymphocytes by Combination of Cytokines

2001 ◽  
Vol 75 (23) ◽  
pp. 11336-11343 ◽  
Author(s):  
Romi Ghose ◽  
Li-Ying Liou ◽  
Christine H. Herrmann ◽  
Andrew P. Rice
Keyword(s):  
T Lymphocytes ◽  
Rna Polymerase Ii ◽  
Interleukin 2 ◽  
Cellular Protein ◽  
Peripheral Blood Lymphocytes ◽  
Tat Protein ◽  
Necrosis Factor Alpha ◽  
Cyclin T1 ◽  
Protein Levels ◽  
Hiv 1

ABSTRACT Combinations of cytokines are known to reactivate transcription and replication of latent human immunodeficiency virus type 1 (HIV-1) proviruses in resting CD4+ T lymphocytes isolated from infected individuals. Transcription of the HIV-1 provirus by RNA polymerase II is strongly stimulated by the viral Tat protein. Tat function is mediated by a cellular protein kinase known as TAK (cyclin T1/P-TEFb) that is composed of Cdk9 and cyclin T1. We have found that treatment of peripheral blood lymphocytes and purified resting CD4+ T lymphocytes with the combination of interleukin-2 (IL-2), IL-6, and tumor necrosis factor alpha resulted in an increase in Cdk9 and cyclin T1 protein levels and an increase in TAK enzymatic activity. The cytokine induction of TAK in resting CD4+ T lymphocytes did not appear to require proliferation of lymphocytes. These results suggest that induction of TAK by cytokines secreted in the microenvironment of lymphoid tissue may be involved in the reactivation of HIV-1 in CD4+ T lymphocytes harboring a latent provirus.

scholarly journals The AFF4 scaffold binds human P-TEFb adjacent to HIV Tat

eLife ◽  
2013 ◽  
Vol 2 ◽  
Author(s):  
Ursula Schulze-Gahmen ◽  
Heather Upton ◽  
Andrew Birnberg ◽  
Katherine Bao ◽  
Seemay Chou ◽  
...  
Keyword(s):  
Rna Polymerase Ii ◽  
Elongation Factor ◽  
Regulatory Proteins ◽  
Tat Protein ◽  
Elongation Complex ◽  
Cyclin T1 ◽  
Subunit Interface ◽  
Hiv Tat ◽  
Gene Transcripts ◽  
Hiv 1

Human positive transcription elongation factor b (P-TEFb) phosphorylates RNA polymerase II and regulatory proteins to trigger elongation of many gene transcripts. The HIV-1 Tat protein selectively recruits P-TEFb as part of a super elongation complex (SEC) organized on a flexible AFF1 or AFF4 scaffold. To understand this specificity and determine if scaffold binding alters P-TEFb conformation, we determined the structure of a tripartite complex containing the recognition regions of P-TEFb and AFF4. AFF4 meanders over the surface of the P-TEFb cyclin T1 (CycT1) subunit but makes no stable contacts with the CDK9 kinase subunit. Interface mutations reduced CycT1 binding and AFF4-dependent transcription. AFF4 is positioned to make unexpected direct contacts with HIV Tat, and Tat enhances P-TEFb affinity for AFF4. These studies define the mechanism of scaffold recognition by P-TEFb and reveal an unanticipated intersubunit pocket on the AFF4 SEC that potentially represents a target for therapeutic intervention against HIV/AIDS.

scholarly journals Phosphorylation of Serine 177 of the Small Hepatitis Delta Antigen Regulates Viral Antigenomic RNA Replication by Interacting with the Processive RNA Polymerase II

2009 ◽  
Vol 84 (3) ◽  
pp. 1430-1438 ◽  
Author(s):  
Shiao-Ya Hong ◽  
Pei-Jer Chen
Keyword(s):  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Posttranslational Modifications ◽  
Transcription Initiation ◽  
Kinase Inhibitor ◽  
Rna Replication ◽  
Hepatitis Delta ◽  
Delta Antigen ◽  
Hepatitis Delta Antigen ◽  
Rnap Ii

ABSTRACT Recent studies revealed that posttranslational modifications (e.g., phosphorylation and methylation) of the small hepatitis delta antigen (SHDAg) are required for hepatitis delta virus (HDV) replication from antigenomic to genomic RNA. The phosphorylation of SHDAg at serine 177 (Ser177) is involved in this step, and this residue is crucial for interaction with RNA polymerase II (RNAP II), the enzyme assumed to be responsible for antigenomic RNA replication. This study demonstrated that SHDAg dephosphorylated at Ser177 interacted preferentially with hypophosphorylated RNAP II (RNAP IIA), which generally binds at the transcription initiation sites. In contrast, the Ser177-phosphorylated counterpart (pSer177-SHDAg) exhibited preferential binding to hyperphosphorylated RNAP II (RNAP IIO). In addition, RNAP IIO associated with pSer177-SHDAg was hyperphosphorylated at both the Ser2 and Ser5 residues of its carboxyl-terminal domain (CTD), which is a hallmark of the transcription elongation isoform. Moreover, the RNAP II CTD kinase inhibitor 5,6-dichloro-1-β-d-ribofuranosyl-benzimidazole (DRB) not only blocked the interaction between pSer177-SHDAg and RNAP IIO but also inhibited HDV antigenomic replication. Our results suggest that the phosphorylation of SHDAg at Ser177 shifted its affinity toward the RNA RNAP IIO isoform and thus is a switch for HDV antigenomic RNA replication from the initiation to the elongation stage.

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 Domains in the SPT5 Protein That Modulate Its Transcriptional Regulatory Properties

2000 ◽  
Vol 20 (9) ◽  
pp. 2970-2983 ◽  
Author(s):  
Dmitri Ivanov ◽  
Youn Tae Kwak ◽  
Jun Guo ◽  
Richard B. Gaynor
Keyword(s):  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Transcriptional Repression ◽  
Transcriptional Elongation ◽  
Tat Protein ◽  
C Terminus ◽  
Heptad Repeats ◽  
And Function ◽  
Hiv 1

ABSTRACT SPT5 and its binding partner SPT4 regulate transcriptional elongation by RNA polymerase II. SPT4 and SPT5 are involved in both 5,6-dichloro-1-β-d-ribofuranosylbenzimidazole (DRB)-mediated transcriptional inhibition and the activation of transcriptional elongation by the human immunodeficiency virus type 1 (HIV-1) Tat protein. Recent data suggest that P-TEFb, which is composed of CDK9 and cyclin T1, is also critical in regulating transcriptional elongation by SPT4 and SPT5. In this study, we analyze the domains of SPT5 that regulate transcriptional elongation in the presence of either DRB or the HIV-1 Tat protein. We demonstrate that SPT5 domains that bind SPT4 and RNA polymerase II, in addition to a region in the C terminus of SPT5 that contains multiple heptad repeats and is designated CTR1, are critical for in vitro transcriptional repression by DRB and activation by the Tat protein. Furthermore, the SPT5 CTR1 domain is a substrate for P-TEFb phosphorylation. These results suggest that C-terminal repeats in SPT5, like those in the RNA polymerase II C-terminal domain, are sites for P-TEFb phosphorylation and function in modulating its transcriptional elongation properties.

Hypoxia Inhibits HIV-1 Transcription.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 1305-1305
Author(s):  
Sergei Nekhai ◽  
Charles Sharroya ◽  
Tatyana Ammosova ◽  
Xiaomei Nui ◽  
Marina Jerebtsova ◽  
...  
Keyword(s):  
Rna Polymerase Ii ◽  
Oxygen Tension ◽  
Protein Phosphatase ◽  
Tissue Oxygenation ◽  
Protein Phosphatase 1 ◽  
Tat Protein ◽  
Cyclin T1 ◽  
Hiv Transcription ◽  
Hiv 1

Abstract The hypoxic response is an important component of the body’s reaction to impaired tissue oxygenation associated with the anemia and vasoocclusive episodes of sickle cell disease (SCD). It has been reported that HIV infection progresses relatively slowly in patients with SCD (Am J Hematol1998;59:199–207). HIV-1 Tat protein promotes transcription of HIV-1 genes by inducing CDK9/cyclin T1 to phosphorylate the C-terminal domain of RNA polymerase-II. Our previous studies indicate that protein phosphatase-1 (PP1) promotes Tat-induced HIV-1 transcription (J Biol Chem2003;278:32189–941), apparently by interacting with HIV-1 Tat, for disruption of this interaction prevents induction of transcription (J Biol Chem2005;280:36364–71). Recently PP1 activity was shown to be decreased in hypoxia in part through increased association of PP1 with NIPP1 (J Cell Physiol 2006 Jul 6; Epub ahead of print). We hypothesized that decreased PP1 activity during hypoxia would reduce HIV-1 transcription and viral replication, and we have obtained experimental results consistent with this hypothesis.Increased expression of nuclear inhibitor of PP1 (NIPP1) was associated with inhibition of HIV-1 transcription and viral replication.Low oxygen tension (3%–6% O2) was associated with transient inhibition of HIV-1 transcription in transfected 293T and HeLa cells.Low oxygen tension was associated with inhibition of HIV-1 transcription in CEM T cells infected with pseudotyped HIV-1 virus. We are now planning to examine the possible role of altered PP1 activity in the observed inhibition of HIV-1 transcription during hypoxia. Thus, a clinical insight from patients with SCD has pointed the way to investigating the influence of hypoxia on HIV transcription. An improved understanding of how oxygen status influences viral activation versus inactivation might open new possibilities for treatment of hidden HIV-1 reservoirs that harbor non-replicating HIV-1 virus.

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