The transcriptional transactivator Tat selectively regulates viral splicing

Jablonski, Joseph; Amelio, Antonio L.; Giacca, Mauro; Caputi, Massimo

doi:10.1093/nar/gkp1105

Cited by 45 publications

(49 citation statements)

References 41 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For example, the regulatory Tat and Rev proteins are produced from fully spliced transcripts. Tat enhances transcription from the viral LTR promoter (Das et al, 2011 and references therein) and influences splice site selection (Jablonski et al, 2010). Rev stimulates nuclear export of the unspliced and singly spliced viral RNAs.…”

Section: Resultsmentioning

confidence: 99%

HIV-1 splicing is controlled by local RNA structure and binding of splicing regulatory proteins at the major 5′ splice site

Müeller

Berkhout

Das

2015

Journal of General Virology

View full text Add to dashboard Cite

The 59 leader region of the human immunodeficiency virus 1 (HIV-1) RNA genome contains the major 59 splice site (ss) that is used in the production of the many spliced viral RNAs. This splice-donor (SD) region can fold into a stable stem-loop structure and the thermodynamic stability of this RNA hairpin influences splicing efficiency. In addition, splicing may be modulated by binding of splicing regulatory (SR) proteins, in particular SF2/ASF (SRSF1), SC35 (SRSF2), SRp40 (SRSF5) and SRp55 (SRSF6), to sequence elements in the SD region. The role of RNA structure and SR protein binding in splicing control was previously studied by functional analysis of mutant SD sequences. The interpretation of these studies was complicated by the fact that most mutations simultaneously affect both structure and sequence elements. We therefore tried to disentangle the contribution of these two variables by designing more precise SD region mutants with a single effect on either the sequence or the structure. The current analysis indicates that HIV-1 splicing at the major 59ss is modulated by both the stability of the local RNA structure and the binding of splicing regulatory proteins.

show abstract

Section: Resultsmentioning

confidence: 99%

HIV-1 splicing is controlled by local RNA structure and binding of splicing regulatory proteins at the major 5′ splice site

Müeller

Berkhout

Das

2015

Journal of General Virology

View full text Add to dashboard Cite

show abstract

“…For example, Tat was shown to influence HIV-1 RNA splicing (38), capping (19,20,80), translation (15,16,18,68), and reverse transcription (3,36,43,44). Moreover, Tat has been proposed to modulate the expression of multiple cellular genes (reviewed in reference 63), to interact with a large number of cellular proteins (reference 32 and references therein), and to inhibit the cellular RNA interference mechanism (6,7,33,67).…”

mentioning

confidence: 99%

The HIV-1 Tat Protein Has a Versatile Role in Activating Viral Transcription

Das

Harwig

Berkhout

2011

J Virol

105

View full text Add to dashboard Cite

It is generally acknowledged that the Tat protein has a pivotal role in HIV-1 replication because it stimulates transcription from the viral long terminal repeat (LTR) promoter by binding to the TAR hairpin in the nascent RNA transcript. However, a multitude of additional Tat functions have been suggested. The importance of these functions is difficult to assess in replication studies with Tat-mutated HIV-1 variants because of the dominant negative effect on viral gene expression. We therefore used an HIV-1 construct that does not depend on the Tat-TAR interaction for transcription to reevaluate whether or not Tat has a second essential function in HIV-1 replication. This HIV-rtTA variant uses the incorporated Tet-On gene expression system for activation of transcription and replicates efficiently upon complete TAR deletion. Here we demonstrated that Tat inactivation does nevertheless severely inhibit replication. Upon long-term culturing, the Tat-minus HIV-rtTA variant acquired mutations in the U3 region that improved promoter activity and reestablished replication. We showed that in the absence of a functional TAR, Tat remains important for viral transcription via Sp1 sequence elements in the U3 promoter region. Substitution of these U3 sequences with nonrelated promoter elements created a virus that replicates efficiently without Tat in SupT1 T cells. These results indicate that Tat has a versatile role in transcription via TAR and U3 elements. The results also imply that Tat has no other essential function in viral replication in cultured T cells.

show abstract

“…In recent work, we show that depletion of Tat-SF1 by gene silencing did not affect basal or Tat-dependent transcription from an HIV-1 CAT reporter in HeLa and HEK293 cells [66]. These data contradict the results obtained by Caputi and coworkers, which have recently reported that down-regulation of Tat-SF1 by siRNAs induces a decrease in transcription and Tat-mediated activation of an HIV-1 reporter minigene in HEK293 cells [67]. In this later work, the effect of reduction of TCERG1 expression was also analyzed.…”

Section: Discussionmentioning

confidence: 57%

Transcription elongation regulator 1 (TCERG1) regulates competent RNA polymerase II-mediated elongation of HIV-1 transcription and facilitates efficient viral replication

et al. 2013

View full text Add to dashboard Cite

BackgroundControl of RNA polymerase II (RNAPII) release from pausing has been proposed as a checkpoint mechanism to ensure optimal RNAPII activity, especially in large, highly regulated genes. HIV-1 gene expression is highly regulated at the level of elongation, which includes transcriptional pausing that is mediated by both viral and cellular factors. Here, we present evidence for a specific role of the elongation-related factor TCERG1 in regulating the extent of HIV-1 elongation and viral replication in vivo.ResultsWe show that TCERG1 depletion diminishes the basal and viral Tat-activated transcription from the HIV-1 LTR. In support of a role for an elongation mechanism in the transcriptional control of HIV-1, we found that TCERG1 modifies the levels of pre-mRNAs generated at distal regions of HIV-1. Most importantly, TCERG1 directly affects the elongation rate of RNAPII transcription in vivo. Furthermore, our data demonstrate that TCERG1 regulates HIV-1 transcription by increasing the rate of RNAPII elongation through the phosphorylation of serine 2 within the carboxyl-terminal domain (CTD) of RNAPII and suggest a mechanism for the involvement of TCERG1 in relieving pausing. Finally, we show that TCERG1 is required for HIV-1 replication.ConclusionsOur study reveals that TCERG1 regulates HIV-1 transcriptional elongation by increasing the elongation rate of RNAPII and phosphorylation of Ser 2 within the CTD. Based on our data, we propose a general mechanism for TCERG1 acting on genes that are regulated at the level of elongation by increasing the rate of RNAPII transcription through the phosphorylation of Ser2. In the case of HIV-1, our evidence provides the basis for further investigation of TCERG1 as a potential therapeutic target for the inhibition of HIV-1 replication

show abstract

The transcriptional transactivator Tat selectively regulates viral splicing

Cited by 45 publications

References 41 publications

HIV-1 splicing is controlled by local RNA structure and binding of splicing regulatory proteins at the major 5′ splice site

HIV-1 splicing is controlled by local RNA structure and binding of splicing regulatory proteins at the major 5′ splice site

The HIV-1 Tat Protein Has a Versatile Role in Activating Viral Transcription

Transcription elongation regulator 1 (TCERG1) regulates competent RNA polymerase II-mediated elongation of HIV-1 transcription and facilitates efficient viral replication

Contact Info

Product

Resources

About