Visualization of Positive Transcription Elongation Factor b (P-TEFb) Activation in Living Cells

Fujinaga, Koh; Luo, Zeping; Schaufele, Fred; Peterlin, B. Matija

doi:10.1074/jbc.m114.605816

Cited by 29 publications

(31 citation statements)

References 50 publications

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“…Additionally, compounds that induce reactivation have recently been found to either induce release of P-TEFb (i.e. PKC agonist PMA, HMBA) (Bernstein and Kappes, 1988; Contreras et al, 2007; Fujinaga et al, 2015; Smith et al, 1992) or function as dual kinase-BET inhibitors targeting BRD4 (i.e. PI3K-mTOR inhibitor PP-242 and the PI3K inhibitor LY294002) (Camarena et al, 2010; Ciceri et al, 2014; Dittmann et al, 2014; Kobayashi et al, 2012).…”

Section: Discussionmentioning

confidence: 99%

Transcriptional Elongation of HSV Immediate Early Genes by the Super Elongation Complex Drives Lytic Infection and Reactivation from Latency

Alfonso

Turner

Beltran

et al. 2017

Cell Host & Microbe

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Summary The cellular transcriptional coactivator HCF-1 is required for initiation of herpes simplex virus (HSV) lytic infection and for reactivation from latency in sensory neurons. HCF-1 stabilizes the viral Immediate Early (IE) genes enhancer complex and mediates chromatin transitions to promote IE transcription initiation. In infected cells, HCF-1 was also found to be associated with a network of transcription elongation components including the Super Elongation Complex (SEC). IE genes exhibit characteristics of genes controlled by transcriptional elongation and the SEC-P-TEFb complex is specifically required to drive the levels of productive IE mRNAs. Significantly, compounds that enhance the levels of SEC-P-TEFb also potently stimulated HSV reactivation from latency both in a sensory ganglia model system and in vivo. Thus, transcriptional elongation of HSV IE genes is a key limiting parameter governing both the initiation of HSV infection and reactivation of latent genomes.

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Section: Discussionmentioning

confidence: 99%

Transcriptional Elongation of HSV Immediate Early Genes by the Super Elongation Complex Drives Lytic Infection and Reactivation from Latency

Alfonso

Turner

Beltran

et al. 2017

Cell Host & Microbe

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“…Multiple positive and negative signals are known to converge on NELF-driven transcriptional pausing. P-TEFb relieves NELF repression through phosphorylation [43] and is itself regulated by cellular stress and signals [44][45][46]. Furthermore, we have shown that NELF interacts with co-repressors including NCoR1-GPS2-HDAC3 at the HIV-1 promoter [47] which may reinforce HIV latency, especially during chronic infection, by facilitating post-translational modifications of histones and chromatin organization.…”

Section: Discussionmentioning

confidence: 99%

Strength of T cell signaling regulates HIV-1 replication and establishment of latency

Gagné

Michaels

Lester

et al. 2018

Preprint

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A major barrier to curing HIV is the long-lived latent reservoir that supports re-emergence of HIV upon treatment interruption. Targeting this reservoir will require mechanistic insights into the establishment and maintenance of HIV latency. Whether T cell signaling at the time of HIV-1 infection influences productive replication or latency is not fully understood. We used a panel of chimeric antigen receptors (CARs) with different ligand binding affinities to induce a range of signaling strengths to model differential T cell receptor signaling at the time of HIV-1 infection. Stimulation of T cell lines or primary CD4+ T cells expressing chimeric antigen receptorssupported HIV-1 infection regardless of affinity for ligand; however, only signaling by the highest affinity receptor facilitated HIV-1 expression. Activation of chimeric antigen receptors that had intermediate and low binding affinities did not support provirus transcription, suggesting that a minimal signal is required for optimal HIV-1 expression. In addition, strong signaling at the time of infection produced a latent population that was readily inducible, whereas latent cells generated in response to weaker signals were not easily reversed. Chromatin immunoprecipitation showed HIV-1 transcription was limited by transcriptional elongation and that robust signaling decreased the presence of negative elongation factor, a pausing factor, by more than 80%. These studies demonstrate that T cell signaling influences HIV-1 infection and the establishment of different subsets of latently infected cells, which may have implications for targeting the HIV reservoir. Author SummaryActivation of CD4+ T cells facilitates HIV-1 infection; however, whether there are minimal signals required for the establishment of infection, replication, and latency has not been explored. To determine how T cell signaling influences HIV-1 infection and the generation of latently infected cells, we used chimeric antigen receptors to create a tunable model. Stronger Gagne, et al. Page 3 signals result in robust HIV-1 expression and an inducible latent population. Minimal signals predispose cells towards latent infections that are refractory to reversal. We discovered that repression of HIV-1 transcription immediately after infection is due to RNA polymerase II pausing and inefficient transcription elongation. These studies demonstrate that signaling events influence the course of HIV-1 infection and have implications for cure strategies. They also provide a mechanistic explanation for why a significant portion of the HIV latent reservoir is not responsive to latency reversing agents which function by modifiying chromatin.

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“…Previously we demonstrated that most LRAs efficiently release P-TEFb from 7SK snRNP and stimulate CDK9 activity [128]. Other compounds such as HMBA; PKC agonists such as PMA, ingenols, and Bryostatin-1; DNA-damaging agents; and nucleotide analogues including Azacytidine also release P-TEFb [161,162,171,172,178,275]. Recently, we established an assay to monitor P-TEFb-release in live cells based on bimolecular fluorescence complementation (BiFC) [275].…”

Section: Increasing P-tefb Activitymentioning

confidence: 99%

“…Other compounds such as HMBA; PKC agonists such as PMA, ingenols, and Bryostatin-1; DNA-damaging agents; and nucleotide analogues including Azacytidine also release P-TEFb [161,162,171,172,178,275]. Recently, we established an assay to monitor P-TEFb-release in live cells based on bimolecular fluorescence complementation (BiFC) [275]. This Visualization of P-TEFb Activation in Cells (V-PAC) assay quickly tests the ability of compounds of interest to activate P-TEFb by releasing it from 7SK snRNP [275].…”

Section: Increasing P-tefb Activitymentioning

confidence: 99%

“…Recently, we established an assay to monitor P-TEFb-release in live cells based on bimolecular fluorescence complementation (BiFC) [275]. This Visualization of P-TEFb Activation in Cells (V-PAC) assay quickly tests the ability of compounds of interest to activate P-TEFb by releasing it from 7SK snRNP [275]. For "shock and kill" approaches for the treatment of HIV-infected patients, it is also necessary to increase the expression levels of CycT1 prior to the release of P-TEFb from 7SK snRNP, since CycT1 protein levels are reduced to undetectable levels in resting CD4+ T cells by post-transcriptional mechanisms [185][186][187].…”

Section: Increasing P-tefb Activitymentioning

confidence: 99%

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P-TEFb as A Promising Therapeutic Target

Fujinaga

2020

Molecules

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The positive transcription elongation factor b (P-TEFb) was first identified as a general factor that stimulates transcription elongation by RNA polymerase II (RNAPII), but soon afterwards it turned out to be an essential cellular co-factor of human immunodeficiency virus (HIV) transcription mediated by viral Tat proteins. Studies on the mechanisms of Tat-dependent HIV transcription have led to radical advances in our knowledge regarding the mechanism of eukaryotic transcription, including the discoveries that P-TEFb-mediated elongation control of cellular transcription is a main regulatory step of gene expression in eukaryotes, and deregulation of P-TEFb activity plays critical roles in many human diseases and conditions in addition to HIV/AIDS. P-TEFb is now recognized as an attractive and promising therapeutic target for inflammation/autoimmune diseases, cardiac hypertrophy, cancer, infectious diseases, etc. In this review article, I will summarize our knowledge about basic P-TEFb functions, the regulatory mechanism of P-TEFb-dependent transcription, P-TEFb’s involvement in biological processes and diseases, and current approaches to manipulating P-TEFb functions for the treatment of these diseases.

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Visualization of Positive Transcription Elongation Factor b (P-TEFb) Activation in Living Cells

Cited by 29 publications

References 50 publications

Transcriptional Elongation of HSV Immediate Early Genes by the Super Elongation Complex Drives Lytic Infection and Reactivation from Latency

Transcriptional Elongation of HSV Immediate Early Genes by the Super Elongation Complex Drives Lytic Infection and Reactivation from Latency

Strength of T cell signaling regulates HIV-1 replication and establishment of latency

P-TEFb as A Promising Therapeutic Target

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