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Mbonye U, Karn J. The cell biology of HIV-1 latency and rebound. Retrovirology 2024; 21:6. [PMID: 38580979 PMCID: PMC10996279 DOI: 10.1186/s12977-024-00639-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/07/2024] Open
Abstract
Transcriptionally latent forms of replication-competent proviruses, present primarily in a small subset of memory CD4+ T cells, pose the primary barrier to a cure for HIV-1 infection because they are the source of the viral rebound that almost inevitably follows the interruption of antiretroviral therapy. Over the last 30 years, many of the factors essential for initiating HIV-1 transcription have been identified in studies performed using transformed cell lines, such as the Jurkat T-cell model. However, as highlighted in this review, several poorly understood mechanisms still need to be elucidated, including the molecular basis for promoter-proximal pausing of the transcribing complex and the detailed mechanism of the delivery of P-TEFb from 7SK snRNP. Furthermore, the central paradox of HIV-1 transcription remains unsolved: how are the initial rounds of transcription achieved in the absence of Tat? A critical limitation of the transformed cell models is that they do not recapitulate the transitions between active effector cells and quiescent memory T cells. Therefore, investigation of the molecular mechanisms of HIV-1 latency reversal and LRA efficacy in a proper physiological context requires the utilization of primary cell models. Recent mechanistic studies of HIV-1 transcription using latently infected cells recovered from donors and ex vivo cellular models of viral latency have demonstrated that the primary blocks to HIV-1 transcription in memory CD4+ T cells are restrictive epigenetic features at the proviral promoter, the cytoplasmic sequestration of key transcription initiation factors such as NFAT and NF-κB, and the vanishingly low expression of the cellular transcription elongation factor P-TEFb. One of the foremost schemes to eliminate the residual reservoir is to deliberately reactivate latent HIV-1 proviruses to enable clearance of persisting latently infected cells-the "Shock and Kill" strategy. For "Shock and Kill" to become efficient, effective, non-toxic latency-reversing agents (LRAs) must be discovered. Since multiple restrictions limit viral reactivation in primary cells, understanding the T-cell signaling mechanisms that are essential for stimulating P-TEFb biogenesis, initiation factor activation, and reversing the proviral epigenetic restrictions have become a prerequisite for the development of more effective LRAs.
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Affiliation(s)
- Uri Mbonye
- Department of Molecular Biology and Microbiology, Case Western Reserve University School of Medicine, Cleveland, OH, 44106, USA.
| | - Jonathan Karn
- Department of Molecular Biology and Microbiology, Case Western Reserve University School of Medicine, Cleveland, OH, 44106, USA.
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2
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Reda O, Monde K, Sugata K, Rahman A, Sakhor W, Rajib SA, Sithi SN, Tan BJY, Niimura K, Motozono C, Maeda K, Ono M, Takeuchi H, Satou Y. HIV-Tocky system to visualize proviral expression dynamics. Commun Biol 2024; 7:344. [PMID: 38509308 PMCID: PMC10954732 DOI: 10.1038/s42003-024-06025-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Accepted: 03/07/2024] [Indexed: 03/22/2024] Open
Abstract
Determinants of HIV-1 latency establishment are yet to be elucidated. HIV reservoir comprises a rare fraction of infected cells that can survive host and virus-mediated killing. In vitro reporter models so far offered a feasible means to inspect this population, but with limited capabilities to dissect provirus silencing dynamics. Here, we describe a new HIV reporter model, HIV-Timer of cell kinetics and activity (HIV-Tocky) with dual fluorescence spontaneous shifting to reveal provirus silencing and reactivation dynamics. This unique feature allows, for the first time, identifying two latent populations: a directly latent, and a recently silenced subset, with the latter having integration features suggestive of stable latency. Our proposed model can help address the heterogeneous nature of HIV reservoirs and offers new possibilities for evaluating eradication strategies.
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Affiliation(s)
- Omnia Reda
- Division of Genomics and Transcriptomics, Joint Research Center for Human Retrovirus Infection, Kumamoto University, Kumamoto, Japan
- Microbiology Department, High Institute of Public Health, Alexandria University, Alexandria, Egypt
| | - Kazuaki Monde
- Department of Microbiology, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
| | - Kenji Sugata
- Division of Genomics and Transcriptomics, Joint Research Center for Human Retrovirus Infection, Kumamoto University, Kumamoto, Japan
| | - Akhinur Rahman
- Division of Genomics and Transcriptomics, Joint Research Center for Human Retrovirus Infection, Kumamoto University, Kumamoto, Japan
| | - Wajihah Sakhor
- Division of Genomics and Transcriptomics, Joint Research Center for Human Retrovirus Infection, Kumamoto University, Kumamoto, Japan
| | - Samiul Alam Rajib
- Division of Genomics and Transcriptomics, Joint Research Center for Human Retrovirus Infection, Kumamoto University, Kumamoto, Japan
| | - Sharmin Nahar Sithi
- Division of Genomics and Transcriptomics, Joint Research Center for Human Retrovirus Infection, Kumamoto University, Kumamoto, Japan
| | - Benjy Jek Yang Tan
- Division of Genomics and Transcriptomics, Joint Research Center for Human Retrovirus Infection, Kumamoto University, Kumamoto, Japan
| | - Koki Niimura
- School of Medicine, Kumamoto University, Kumamoto, Japan
| | - Chihiro Motozono
- Division of Infection and Immunology, Joint Research Center for Human Retrovirus Infection, Kumamoto University, Kumamoto, Japan
| | - Kenji Maeda
- Division of Antiviral Therapy, Joint Research Center for Human Retrovirus Infection, Kagoshima University, Kagoshima, Japan
| | - Masahiro Ono
- Department of Life Sciences, Imperial College London, London, UK
| | - Hiroaki Takeuchi
- Department of High-risk Infectious Disease Control, Tokyo Medical and Dental University (TMDU), Tokyo, Japan
| | - Yorifumi Satou
- Division of Genomics and Transcriptomics, Joint Research Center for Human Retrovirus Infection, Kumamoto University, Kumamoto, Japan.
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3
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Cisneros WJ, Walter M, Soliman SH, Simons LM, Cornish D, Halle AW, Kim EY, Wolinsky SM, Shilatifard A, Hultquist JF. Release of P-TEFb from the Super Elongation Complex promotes HIV-1 latency reversal. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.01.582881. [PMID: 38464055 PMCID: PMC10925308 DOI: 10.1101/2024.03.01.582881] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/12/2024]
Abstract
The persistence of HIV-1 in long-lived latent reservoirs during suppressive antiretroviral therapy (ART) remains one of the principal barriers to a functional cure. Blocks to transcriptional elongation play a central role in maintaining the latent state, and several latency reversal strategies focus on the release of positive transcription elongation factor b (P-TEFb) from sequestration by negative regulatory complexes, such as the 7SK complex and BRD4. Another major cellular reservoir of P-TEFb is in Super Elongation Complexes (SECs), which play broad regulatory roles in host gene expression. Still, it is unknown if the release of P-TEFb from SECs is a viable latency reversal strategy. Here, we demonstrate that the SEC is not required for HIV-1 replication in primary CD4+ T cells and that a small molecular inhibitor of the P-TEFb/SEC interaction (termed KL-2) increases viral transcription. KL-2 acts synergistically with other latency reversing agents (LRAs) to reactivate viral transcription in several cell line models of latency in a manner that is, at least in part, dependent on the viral Tat protein. Finally, we demonstrate that KL-2 enhances viral reactivation in peripheral blood mononuclear cells (PBMCs) from people living with HIV on suppressive ART, most notably in combination with inhibitor of apoptosis protein antagonists (IAPi). Taken together, these results suggest that the release of P-TEFb from cellular SECs may be a novel route for HIV-1 latency reactivation.
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Affiliation(s)
- William J. Cisneros
- Division of Infectious Diseases, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
- Center for Pathogen Genomics and Microbial Evolution, Havey Institute for Global Health, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Miriam Walter
- Division of Infectious Diseases, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Shimaa H.A. Soliman
- Simpson Querrey Institute for Epigenetics, Department of Biochemistry and Molecular Genetics Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Lacy M. Simons
- Division of Infectious Diseases, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
- Center for Pathogen Genomics and Microbial Evolution, Havey Institute for Global Health, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Daphne Cornish
- Division of Infectious Diseases, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
- Center for Pathogen Genomics and Microbial Evolution, Havey Institute for Global Health, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Ariel W. Halle
- Division of Infectious Diseases, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
- Center for Pathogen Genomics and Microbial Evolution, Havey Institute for Global Health, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Eun-Young Kim
- Division of Infectious Diseases, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Steven M. Wolinsky
- Division of Infectious Diseases, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Ali Shilatifard
- Simpson Querrey Institute for Epigenetics, Department of Biochemistry and Molecular Genetics Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Judd F. Hultquist
- Division of Infectious Diseases, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
- Center for Pathogen Genomics and Microbial Evolution, Havey Institute for Global Health, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
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4
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Hyder U, Shukla A, Challa A, D’Orso I. HIV-1 Proviral Genome Engineering with CRISPR-Cas9 for Mechanistic Studies. Viruses 2024; 16:287. [PMID: 38400062 PMCID: PMC10892460 DOI: 10.3390/v16020287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2023] [Revised: 02/01/2024] [Accepted: 02/08/2024] [Indexed: 02/25/2024] Open
Abstract
HIV-1 latency remains a barrier to a functional cure because of the ability of virtually silent yet inducible proviruses within reservoir cells to transcriptionally reactivate upon cell stimulation. HIV-1 reactivation occurs through the sequential action of host transcription factors (TFs) during the "host phase" and the viral TF Tat during the "viral phase", which together facilitate the positive feedback loop required for exponential transcription, replication, and pathogenesis. The sequential action of these TFs poses a challenge to precisely delineate the contributions of the host and viral phases of the transcriptional program to guide future mechanistic and therapeutic studies. To address this limitation, we devised a genome engineering approach to mutate tat and create a genetically matched pair of Jurkat T cell clones harboring HIV-1 at the same integration site with and without Tat expression. By comparing the transcriptional profile of both clones, the transition point between the host and viral phases was defined, providing a system that enables the temporal mechanistic interrogation of HIV-1 transcription prior to and after Tat synthesis. Importantly, this CRISPR method is broadly applicable to knockout individual viral proteins or genomic regulatory elements to delineate their contributions to various aspects of the viral life cycle and ultimately may facilitate therapeutic approaches in our race towards achieving a functional cure.
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Affiliation(s)
| | | | | | - Iván D’Orso
- Department of Microbiology, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; (U.H.); (A.S.); (A.C.)
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5
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Meeussen JVW, Lenstra TL. Time will tell: comparing timescales to gain insight into transcriptional bursting. Trends Genet 2024; 40:160-174. [PMID: 38216391 PMCID: PMC10860890 DOI: 10.1016/j.tig.2023.11.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 11/27/2023] [Accepted: 11/27/2023] [Indexed: 01/14/2024]
Abstract
Recent imaging studies have captured the dynamics of regulatory events of transcription inside living cells. These events include transcription factor (TF) DNA binding, chromatin remodeling and modification, enhancer-promoter (E-P) proximity, cluster formation, and preinitiation complex (PIC) assembly. Together, these molecular events culminate in stochastic bursts of RNA synthesis, but their kinetic relationship remains largely unclear. In this review, we compare the timescales of upstream regulatory steps (input) with the kinetics of transcriptional bursting (output) to generate mechanistic models of transcription dynamics in single cells. We highlight open questions and potential technical advances to guide future endeavors toward a quantitative and kinetic understanding of transcription regulation.
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Affiliation(s)
- Joseph V W Meeussen
- Division of Gene Regulation, The Netherlands Cancer Institute, Oncode Institute, Amsterdam 1066CX, The Netherlands
| | - Tineke L Lenstra
- Division of Gene Regulation, The Netherlands Cancer Institute, Oncode Institute, Amsterdam 1066CX, The Netherlands.
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6
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Hunt G, Vaid R, Pirogov S, Pfab A, Ziegenhain C, Sandberg R, Reimegård J, Mannervik M. Tissue-specific RNA Polymerase II promoter-proximal pause release and burst kinetics in a Drosophila embryonic patterning network. Genome Biol 2024; 25:2. [PMID: 38166964 PMCID: PMC10763363 DOI: 10.1186/s13059-023-03135-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2023] [Accepted: 11/30/2023] [Indexed: 01/05/2024] Open
Abstract
BACKGROUND Formation of tissue-specific transcriptional programs underlies multicellular development, including dorsoventral (DV) patterning of the Drosophila embryo. This involves interactions between transcriptional enhancers and promoters in a chromatin context, but how the chromatin landscape influences transcription is not fully understood. RESULTS Here we comprehensively resolve differential transcriptional and chromatin states during Drosophila DV patterning. We find that RNA Polymerase II pausing is established at DV promoters prior to zygotic genome activation (ZGA), that pausing persists irrespective of cell fate, but that release into productive elongation is tightly regulated and accompanied by tissue-specific P-TEFb recruitment. DV enhancers acquire distinct tissue-specific chromatin states through CBP-mediated histone acetylation that predict the transcriptional output of target genes, whereas promoter states are more tissue-invariant. Transcriptome-wide inference of burst kinetics in different cell types revealed that while DV genes are generally characterized by a high burst size, either burst size or frequency can differ between tissues. CONCLUSIONS The data suggest that pausing is established by pioneer transcription factors prior to ZGA and that release from pausing is imparted by enhancer chromatin state to regulate bursting in a tissue-specific manner in the early embryo. Our results uncover how developmental patterning is orchestrated by tissue-specific bursts of transcription from Pol II primed promoters in response to enhancer regulatory cues.
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Affiliation(s)
- George Hunt
- Department Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Roshan Vaid
- Department Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Sergei Pirogov
- Department Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Alexander Pfab
- Department Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | | | - Rickard Sandberg
- Department Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden
| | - Johan Reimegård
- Department Cell and Molecular Biology, National Bioinformatics Infrastructure Sweden, Science for Life Laboratory, Uppsala University, Uppsala, Sweden
| | - Mattias Mannervik
- Department Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden.
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7
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Chang J, Parent LJ. HIV-1 Gag co-localizes with euchromatin histone marks at the nuclear periphery. J Virol 2023; 97:e0117923. [PMID: 37991367 PMCID: PMC10734548 DOI: 10.1128/jvi.01179-23] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Accepted: 10/27/2023] [Indexed: 11/23/2023] Open
Abstract
IMPORTANCE The traditional view of retrovirus assembly posits that packaging of gRNA by HIV-1 Gag occurs in the cytoplasm or at the plasma membrane. However, our previous studies showing that HIV-1 Gag enters the nucleus and binds to USvRNA at transcription sites suggest that gRNA selection may occur in the nucleus. In the present study, we observed that HIV-1 Gag trafficked to the nucleus and co-localized with USvRNA within 8 hours of expression. In infected T cells (J-Lat 10.6) reactivated from latency and in a HeLa cell line stably expressing an inducible Rev-dependent HIV-1 construct, we found that Gag preferentially localized with euchromatin histone marks associated with enhancer and promoter regions near the nuclear periphery, which is the favored site HIV-1 integration. These observations support the innovative hypothesis that HIV-1 Gag associates with euchromatin-associated histones to localize to active transcription sites, promoting capture of newly synthesized gRNA for packaging.
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Affiliation(s)
- Jordan Chang
- Department of Medicine, Pennsylvania State University College of Medicine, Hershey, Pennsylvania, USA
| | - Leslie J. Parent
- Department of Medicine, Pennsylvania State University College of Medicine, Hershey, Pennsylvania, USA
- Department of Microbiology and Immunology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania, USA
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8
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Wang Z, Luo S, Zhang Z, Zhou T, Zhang J. 4D nucleome equation predicts gene expression controlled by long-range enhancer-promoter interaction. PLoS Comput Biol 2023; 19:e1011722. [PMID: 38109463 PMCID: PMC10760824 DOI: 10.1371/journal.pcbi.1011722] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Revised: 01/02/2024] [Accepted: 11/28/2023] [Indexed: 12/20/2023] Open
Abstract
Recent experimental evidence strongly supports that three-dimensional (3D) long-range enhancer-promoter (E-P) interactions have important influences on gene-expression dynamics, but it is unclear how the interaction information is translated into gene expression over time (4D). To address this question, we developed a general theoretical framework (named as a 4D nucleome equation), which integrates E-P interactions on chromatin and biochemical reactions of gene transcription. With this equation, we first present the distribution of mRNA counts as a function of the E-P genomic distance and then reveal a power-law scaling of the expression level in this distance. Interestingly, we find that long-range E-P interactions can induce bimodal and trimodal mRNA distributions. The 4D nucleome equation also allows for model selection and parameter inference. When this equation is applied to the mouse embryonic stem cell smRNA-FISH data and the E-P genomic-distance data, the predicted E-P contact probability and mRNA distribution are in good agreement with experimental results. Further statistical inference indicates that the E-P interactions prefer to modulate the mRNA level by controlling promoter activation and transcription initiation rates. Our model and results provide quantitative insights into both spatiotemporal gene-expression determinants (i.e., long-range E-P interactions) and cellular fates during development.
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Affiliation(s)
- Zihao Wang
- Guangdong Province Key Laboratory of Computational, Sun Yat-sen University, Guangzhou, People’s Republic of China
- School of Mathematics, Sun Yat-Sen University, Guangzhou, People’s Republic of China
| | - Songhao Luo
- Guangdong Province Key Laboratory of Computational, Sun Yat-sen University, Guangzhou, People’s Republic of China
- School of Mathematics, Sun Yat-Sen University, Guangzhou, People’s Republic of China
| | - Zhenquan Zhang
- Guangdong Province Key Laboratory of Computational, Sun Yat-sen University, Guangzhou, People’s Republic of China
- School of Mathematics, Sun Yat-Sen University, Guangzhou, People’s Republic of China
| | - Tianshou Zhou
- Guangdong Province Key Laboratory of Computational, Sun Yat-sen University, Guangzhou, People’s Republic of China
- School of Mathematics, Sun Yat-Sen University, Guangzhou, People’s Republic of China
| | - Jiajun Zhang
- Guangdong Province Key Laboratory of Computational, Sun Yat-sen University, Guangzhou, People’s Republic of China
- School of Mathematics, Sun Yat-Sen University, Guangzhou, People’s Republic of China
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9
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D’Orso I, Forst CV. Mathematical Models of HIV-1 Dynamics, Transcription, and Latency. Viruses 2023; 15:2119. [PMID: 37896896 PMCID: PMC10612035 DOI: 10.3390/v15102119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Revised: 10/10/2023] [Accepted: 10/18/2023] [Indexed: 10/29/2023] Open
Abstract
HIV-1 latency is a major barrier to curing infections with antiretroviral therapy and, consequently, to eliminating the disease globally. The establishment, maintenance, and potential clearance of latent infection are complex dynamic processes and can be best described with the help of mathematical models followed by experimental validation. Here, we review the use of viral dynamics models for HIV-1, with a focus on applications to the latent reservoir. Such models have been used to explain the multi-phasic decay of viral load during antiretroviral therapy, the early seeding of the latent reservoir during acute infection and the limited inflow during treatment, the dynamics of viral blips, and the phenomenon of post-treatment control. Finally, we discuss that mathematical models have been used to predict the efficacy of potential HIV-1 cure strategies, such as latency-reversing agents, early treatment initiation, or gene therapies, and to provide guidance for designing trials of these novel interventions.
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Affiliation(s)
- Iván D’Orso
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA;
| | - Christian V. Forst
- Department of Genetics and Genomic Sciences, Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
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10
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Chen PT, Zoller B, Levo M, Gregor T. Gene Activity as the Predictive Indicator for Transcriptional Bursting Dynamics. ARXIV 2023:arXiv:2304.08770v2. [PMID: 37131882 PMCID: PMC10153294] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Transcription commonly occurs in bursts, with alternating productive (ON) and quiescent (OFF) periods, governing mRNA production rates. Yet, how transcription is regulated through bursting dynamics remains unresolved. In this study, we conduct real-time measurements of endogenous transcriptional bursting with single-mRNA sensitivity. Leveraging the diverse transcriptional activities in early fly embryos, we uncover stringent relationships between bursting parameters. Specifically, we find that the durations of ON and OFF periods are linked. Regardless of the developmental stage or body-axis position, gene activity levels predict the average ON and OFF periods of individual alleles. Lowly transcribing alleles predominantly modulate OFF durations (burst frequency), while highly transcribing alleles primarily tune ON durations (burst size). Importantly, these relationships persist even under perturbation of cis-regulatory elements or trans-factors. This suggests a novel mechanistic constraint governing bursting dynamics rather than a modular control of distinct parameters by distinct regulatory processes. Our study provides a foundation for future investigations into the molecular mechanisms underpinning spatiotemporal transcriptional control.
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Affiliation(s)
- Po-Ta Chen
- Joseph Henry Laboratories of Physics & Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA
| | - Benjamin Zoller
- Joseph Henry Laboratories of Physics & Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA
- Department of Stem Cell and Developmental Biology, CNRS UMR3738 Paris Cité, Institut Pasteur, 25 rue du Docteur Roux, 75015 Paris, France
| | - Michal Levo
- Joseph Henry Laboratories of Physics & Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA
| | - Thomas Gregor
- Joseph Henry Laboratories of Physics & Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA
- Department of Stem Cell and Developmental Biology, CNRS UMR3738 Paris Cité, Institut Pasteur, 25 rue du Docteur Roux, 75015 Paris, France
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11
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Damour A, Slaninova V, Radulescu O, Bertrand E, Basyuk E. Transcriptional Stochasticity as a Key Aspect of HIV-1 Latency. Viruses 2023; 15:1969. [PMID: 37766375 PMCID: PMC10535884 DOI: 10.3390/v15091969] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Revised: 09/16/2023] [Accepted: 09/18/2023] [Indexed: 09/29/2023] Open
Abstract
This review summarizes current advances in the role of transcriptional stochasticity in HIV-1 latency, which were possible in a large part due to the development of single-cell approaches. HIV-1 transcription proceeds in bursts of RNA production, which stem from the stochastic switching of the viral promoter between ON and OFF states. This switching is caused by random binding dynamics of transcription factors and nucleosomes to the viral promoter and occurs at several time scales from minutes to hours. Transcriptional bursts are mainly controlled by the core transcription factors TBP, SP1 and NF-κb, the chromatin status of the viral promoter and RNA polymerase II pausing. In particular, spontaneous variability in the promoter chromatin creates heterogeneity in the response to activators such as TNF-α, which is then amplified by the Tat feedback loop to generate high and low viral transcriptional states. This phenomenon is likely at the basis of the partial and stochastic response of latent T cells from HIV-1 patients to latency-reversing agents, which is a barrier for the development of shock-and-kill strategies of viral eradication. A detailed understanding of the transcriptional stochasticity of HIV-1 and the possibility to precisely model this phenomenon will be important assets to develop more effective therapeutic strategies.
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Affiliation(s)
- Alexia Damour
- MFP UMR 5234 CNRS, Université de Bordeaux, 33076 Bordeaux, France;
| | - Vera Slaninova
- IGH UMR 9002 CNRS, Université de Montpellier, 34094 Montpellier, France;
| | - Ovidiu Radulescu
- LPHI, UMR 5294 CNRS, University of Montpellier, 34095 Montpellier, France;
| | - Edouard Bertrand
- IGH UMR 9002 CNRS, Université de Montpellier, 34094 Montpellier, France;
| | - Eugenia Basyuk
- MFP UMR 5234 CNRS, Université de Bordeaux, 33076 Bordeaux, France;
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12
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Douaihy M, Topno R, Lagha M, Bertrand E, Radulescu O. BurstDECONV: a signal deconvolution method to uncover mechanisms of transcriptional bursting in live cells. Nucleic Acids Res 2023; 51:e88. [PMID: 37522372 PMCID: PMC10484743 DOI: 10.1093/nar/gkad629] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Revised: 06/23/2023] [Accepted: 07/17/2023] [Indexed: 08/01/2023] Open
Abstract
Monitoring transcription in living cells gives access to the dynamics of this complex fundamental process. It reveals that transcription is discontinuous, whereby active periods (bursts) are separated by one or several types of inactive periods of distinct lifetimes. However, decoding temporal fluctuations arising from live imaging and inferring the distinct transcriptional steps eliciting them is a challenge. We present BurstDECONV, a novel statistical inference method that deconvolves signal traces into individual transcription initiation events. We use the distribution of waiting times between successive polymerase initiation events to identify mechanistic features of transcription such as the number of rate-limiting steps and their kinetics. Comparison of our method to alternative methods emphasizes its advantages in terms of precision and flexibility. Unique features such as the direct determination of the number of promoter states and the simultaneous analysis of several potential transcription models make BurstDECONV an ideal analytic framework for live cell transcription imaging experiments. Using simulated realistic data, we found that our method is robust with regards to noise or suboptimal experimental designs. To show its generality, we applied it to different biological contexts such as Drosophila embryos or human cells.
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Affiliation(s)
- Maria Douaihy
- LPHI, University of Montpellier and CNRS, Place Eugène Bataillon, Montpellier 34095, France
- IGMM, University of Montpellier and CNRS, 1919 Rte de Mende, Montpellier 34090, France
| | - Rachel Topno
- LPHI, University of Montpellier and CNRS, Place Eugène Bataillon, Montpellier 34095, France
- IGH, University of Montpellier and CNRS, 141 Rue de la Cardonille, Montpellier 34094, France
| | - Mounia Lagha
- IGMM, University of Montpellier and CNRS, 1919 Rte de Mende, Montpellier 34090, France
| | - Edouard Bertrand
- IGH, University of Montpellier and CNRS, 141 Rue de la Cardonille, Montpellier 34094, France
| | - Ovidiu Radulescu
- LPHI, University of Montpellier and CNRS, Place Eugène Bataillon, Montpellier 34095, France
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13
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Wildner C, Mehta GD, Ball DA, Karpova TS, Koeppl H. Bayesian analysis dissects kinetic modulation during non-stationary gene expression. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.20.545522. [PMID: 37503023 PMCID: PMC10370195 DOI: 10.1101/2023.06.20.545522] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
Labelling of nascent stem loops with fluorescent proteins has fostered the visualization of transcription in living cells. Quantitative analysis of recorded fluorescence traces can shed light on kinetic transcription parameters and regulatory mechanisms. However, existing methods typically focus on steady state dynamics. Here, we combine a stochastic process transcription model with a hierarchical Bayesian method to infer global as well locally shared parameters for groups of cells and recover unobserved quantities such as initiation times and polymerase loading of the gene. We apply our approach to the cyclic response of the yeast CUP1 locus to heavy metal stress. Within the previously described slow cycle of transcriptional activity on the scale of minutes, we discover fast time-modulated bursting on the scale of seconds. Model comparison suggests that slow oscillations of transcriptional output are regulated by the amplitude of the bursts. Several polymerases may initiate during a burst.
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Affiliation(s)
- Christian Wildner
- Centre for Synthetic Biology, Technische Universität Darmstadt, Darmstadt, 64283, Germany
| | - Gunjan D. Mehta
- Department of Biotechnology, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, Telangana-502285, India
| | - David A. Ball
- National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Tatiana S. Karpova
- National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Heinz Koeppl
- Centre for Synthetic Biology, Technische Universität Darmstadt, Darmstadt, 64283, Germany
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14
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Forbes Beadle L, Zhou H, Rattray M, Ashe HL. Modulation of transcription burst amplitude underpins dosage compensation in the Drosophila embryo. Cell Rep 2023; 42:112382. [PMID: 37060568 PMCID: PMC10283159 DOI: 10.1016/j.celrep.2023.112382] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Revised: 02/03/2023] [Accepted: 03/27/2023] [Indexed: 04/16/2023] Open
Abstract
Dosage compensation, the balancing of X-linked gene expression between sexes and to the autosomes, is critical to an organism's fitness and survival. In Drosophila, dosage compensation involves hypertranscription of the male X chromosome. Here, we use quantitative live imaging and modeling at single-cell resolution to study X chromosome dosage compensation in Drosophila. We show that the four X chromosome genes studied undergo transcriptional bursting in male and female embryos. Mechanistically, our data reveal that transcriptional upregulation of male X chromosome genes is primarily mediated by a higher RNA polymerase II initiation rate and burst amplitude across the expression domain. In contrast, burst frequency is spatially modulated in nuclei within the expression domain in response to different transcription factor concentrations to tune the transcriptional response. Together, these data show how the local and global regulation of distinct burst parameters can establish the complex transcriptional outputs underpinning developmental patterning.
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Affiliation(s)
- Lauren Forbes Beadle
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PT, UK
| | - Hongpeng Zhou
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PT, UK
| | - Magnus Rattray
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PT, UK.
| | - Hilary L Ashe
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PT, UK.
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15
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Luo S, Zhang Z, Wang Z, Yang X, Chen X, Zhou T, Zhang J. Inferring transcriptional bursting kinetics from single-cell snapshot data using a generalized telegraph model. ROYAL SOCIETY OPEN SCIENCE 2023; 10:221057. [PMID: 37035293 PMCID: PMC10073913 DOI: 10.1098/rsos.221057] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Accepted: 03/13/2023] [Indexed: 06/19/2023]
Abstract
Gene expression has inherent stochasticity resulting from transcription's burst manners. Single-cell snapshot data can be exploited to rigorously infer transcriptional burst kinetics, using mathematical models as blueprints. The classical telegraph model (CTM) has been widely used to explain transcriptional bursting with Markovian assumptions. However, growing evidence suggests that the gene-state dwell times are generally non-exponential, as gene-state switching is a multi-step process in organisms. Therefore, interpretable non-Markovian mathematical models and efficient statistical inference methods are urgently required in investigating transcriptional burst kinetics. We develop an interpretable and tractable model, the generalized telegraph model (GTM), to characterize transcriptional bursting that allows arbitrary dwell-time distributions, rather than exponential distributions, to be incorporated into the ON and OFF switching process. Based on the GTM, we propose an inference method for transcriptional bursting kinetics using an approximate Bayesian computation framework. This method demonstrates an efficient and scalable estimation of burst frequency and burst size on synthetic data. Further, the application of inference to genome-wide data from mouse embryonic fibroblasts reveals that GTM would estimate lower burst frequency and higher burst size than those estimated by CTM. In conclusion, the GTM and the corresponding inference method are effective tools to infer dynamic transcriptional bursting from static single-cell snapshot data.
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Affiliation(s)
- Songhao Luo
- Guangdong Province Key Laboratory of Computational Science, Sun Yat-sen University, Guangzhou, Guangdong Province 510275, People's Republic of China
- School of Mathematics, Sun Yat-sen University, Guangzhou, Guangdong Province 510275, People's Republic of China
| | - Zhenquan Zhang
- Guangdong Province Key Laboratory of Computational Science, Sun Yat-sen University, Guangzhou, Guangdong Province 510275, People's Republic of China
- School of Mathematics, Sun Yat-sen University, Guangzhou, Guangdong Province 510275, People's Republic of China
| | - Zihao Wang
- Guangdong Province Key Laboratory of Computational Science, Sun Yat-sen University, Guangzhou, Guangdong Province 510275, People's Republic of China
- School of Mathematics, Sun Yat-sen University, Guangzhou, Guangdong Province 510275, People's Republic of China
| | - Xiyan Yang
- School of Financial Mathematics and Statistics, Guangdong University of Finance, Guangzhou 510521, People's Republic of China
| | - Xiaoxuan Chen
- Guangdong Province Key Laboratory of Computational Science, Sun Yat-sen University, Guangzhou, Guangdong Province 510275, People's Republic of China
- School of Mathematics, Sun Yat-sen University, Guangzhou, Guangdong Province 510275, People's Republic of China
| | - Tianshou Zhou
- Guangdong Province Key Laboratory of Computational Science, Sun Yat-sen University, Guangzhou, Guangdong Province 510275, People's Republic of China
- School of Mathematics, Sun Yat-sen University, Guangzhou, Guangdong Province 510275, People's Republic of China
| | - Jiajun Zhang
- Guangdong Province Key Laboratory of Computational Science, Sun Yat-sen University, Guangzhou, Guangdong Province 510275, People's Republic of China
- School of Mathematics, Sun Yat-sen University, Guangzhou, Guangdong Province 510275, People's Republic of China
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16
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Soliman SH, Cisneros WJ, Iwanaszko M, Aoi Y, Ganesan S, Walter M, Zeidner JM, Mishra RK, Kim EY, Wolinsky SM, Hultquist JF, Shilatifard A. Enhancing HIV-1 latency reversal through regulating the elongating RNA Pol II pause-release by a small-molecule disruptor of PAF1C. SCIENCE ADVANCES 2023; 9:eadf2468. [PMID: 36888719 PMCID: PMC9995073 DOI: 10.1126/sciadv.adf2468] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/08/2022] [Accepted: 02/03/2023] [Indexed: 05/03/2023]
Abstract
The polymerase-associated factor 1 complex (PAF1C) is a key, post-initiation transcriptional regulator of both promoter-proximal pausing and productive elongation catalyzed by RNA Pol II and is also involved in transcriptional repression of viral gene expression during human immunodeficiency virus-1 (HIV-1) latency. Using a molecular docking-based compound screen in silico and global sequencing-based candidate evaluation in vivo, we identified a first-in-class, small-molecule inhibitor of PAF1C (iPAF1C) that disrupts PAF1 chromatin occupancy and induces global release of promoter-proximal paused RNA Pol II into gene bodies. Transcriptomic analysis revealed that iPAF1C treatment mimics acute PAF1 subunit depletion and impairs RNA Pol II pausing at heat shock-down-regulated genes. Furthermore, iPAF1C enhances the activity of diverse HIV-1 latency reversal agents both in cell line latency models and in primary cells from persons living with HIV-1. In sum, this study demonstrates that efficient disruption of PAF1C by a first-in-class, small-molecule inhibitor may have therapeutic potential for improving current HIV-1 latency reversal strategies.
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Affiliation(s)
- Shimaa H. A. Soliman
- Simpson Querrey Institute for Epigenetics, Department of Biochemistry and Molecular Genetics Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - William J. Cisneros
- Division of Infectious Diseases, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
- Center for Pathogen Genomics and Microbial Evolution, Havey Institute for Global Health, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Marta Iwanaszko
- Simpson Querrey Institute for Epigenetics, Department of Biochemistry and Molecular Genetics Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Yuki Aoi
- Simpson Querrey Institute for Epigenetics, Department of Biochemistry and Molecular Genetics Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Sheetal Ganesan
- Simpson Querrey Institute for Epigenetics, Department of Biochemistry and Molecular Genetics Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Miriam Walter
- Division of Infectious Diseases, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Jacob M. Zeidner
- Simpson Querrey Institute for Epigenetics, Department of Biochemistry and Molecular Genetics Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Rama K. Mishra
- Simpson Querrey Institute for Epigenetics, Department of Biochemistry and Molecular Genetics Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Eun-Young Kim
- Division of Infectious Diseases, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Steven M. Wolinsky
- Division of Infectious Diseases, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Judd F. Hultquist
- Division of Infectious Diseases, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
- Center for Pathogen Genomics and Microbial Evolution, Havey Institute for Global Health, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Ali Shilatifard
- Simpson Querrey Institute for Epigenetics, Department of Biochemistry and Molecular Genetics Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
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17
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Chang J, Parent LJ. HIV-1 Gag colocalizes with euchromatin histone marks at the nuclear periphery. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.24.529990. [PMID: 36865288 PMCID: PMC9980143 DOI: 10.1101/2023.02.24.529990] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2023]
Abstract
The retroviral Gag protein of human immunodeficiency virus type 1 (HIV-1) plays a central role in the selection of unspliced viral genomic RNA for packaging into new virions. Previously, we demonstrated that full-length HIV-1 Gag undergoes nuclear trafficking where it associates with unspliced viral RNA (vRNA) at transcription sites. To further explore the kinetics of HIV-1 Gag nuclear localization, we used biochemical and imaging techniques to examine the timing of HIV-1 entry into the nucleus. We also aimed to determine more precisely Gag's subnuclear distribution to test the hypothesis that Gag would be associated with euchromatin, the transcriptionally active region of the nucleus. We observed that HIV-1 Gag localized to the nucleus shortly after its synthesis in the cytoplasm, suggesting that nuclear trafficking was not strictly concentration-dependent. Furthermore, we found that HIV-1 Gag preferentially localized to the transcriptionally active euchromatin fraction compared to the heterochromatin-rich region in a latently-infected CD4+ T cell line (J-Lat 10.6) treated with latency-reversal agents. Interestingly, HIV-1 Gag was more closely associated with transcriptionally-active histone markers near the nuclear periphery, where the HIV-1 provirus was previously shown to integrate. Although the precise function of Gag's association with histones in transcriptionally-active chromatin remains uncertain, together with previous reports, this finding is consistent with a potential role for euchromatin-associated Gag molecules to select newly transcribed unspliced vRNA during the initial stage of virion assembly. Importance The traditional view of retroviral assembly posits that HIV-1 Gag selection of unspliced vRNA begins in the cytoplasm. However, our previous studies demonstrated that HIV-1 Gag enters the nucleus and binds to unspliced HIV-1 RNA at transcription sites, suggesting that genomic RNA selection may occur in the nucleus. In the present study, we observed nuclear entry of HIV-1 Gag and co-localization with unspliced viral RNA within 8 hours post-expression. In CD4+ T cells (J-Lat 10.6) treated with latency reversal agents, as well as a HeLa cell line stably expressing an inducible Rev-dependent provirus, we found that HIV-1 Gag preferentially localized with histone marks associated with enhancer and promoter regions of transcriptionally active euchromatin near the nuclear periphery, which favors HIV-1 proviral integration sites. These observations support the hypothesis that HIV-1 Gag hijacks euchromatin-associated histones to localize to active transcription sites, promoting capture of newly synthesized genomic RNA for packaging.
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18
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Luo S, Wang Z, Zhang Z, Zhou T, Zhang J. Genome-wide inference reveals that feedback regulations constrain promoter-dependent transcriptional burst kinetics. Nucleic Acids Res 2022; 51:68-83. [PMID: 36583343 PMCID: PMC9874261 DOI: 10.1093/nar/gkac1204] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Revised: 11/06/2022] [Accepted: 12/06/2022] [Indexed: 12/31/2022] Open
Abstract
Gene expression in mammalian cells is highly variable and episodic, resulting in a series of discontinuous bursts of mRNAs. A challenge is to understand how static promoter architecture and dynamic feedback regulations dictate bursting on a genome-wide scale. Although single-cell RNA sequencing (scRNA-seq) provides an opportunity to address this challenge, effective analytical methods are scarce. We developed an interpretable and scalable inference framework, which combined experimental data with a mechanistic model to infer transcriptional burst kinetics (sizes and frequencies) and feedback regulations. Applying this framework to scRNA-seq data generated from embryonic mouse fibroblast cells, we found Simpson's paradoxes, i.e. genome-wide burst kinetics exhibit different characteristics in two cases without and with distinguishing feedback regulations. We also showed that feedbacks differently modulate burst frequencies and sizes and conceal the effects of transcription start site distributions on burst kinetics. Notably, only in the presence of positive feedback, TATA genes are expressed with high burst frequencies and enhancer-promoter interactions mainly modulate burst frequencies. The developed inference method provided a flexible and efficient way to investigate transcriptional burst kinetics and the obtained results would be helpful for understanding cell development and fate decision.
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Affiliation(s)
| | | | - Zhenquan Zhang
- Guangdong Province Key Laboratory of Computational Science, Sun Yat-sen University, Guangzhou, 510275, P. R. China,School of Mathematics, Sun Yat-sen University, Guangzhou, Guangdong Province, 510275, P. R. China
| | - Tianshou Zhou
- Correspondence may also be addressed to Tianshou Zhou. Tel: +86 20 84134958;
| | - Jiajun Zhang
- To whom correspondence should be addressed. Tel: +86 20 84111829;
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19
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Nühn MM, Gumbs SBH, Buchholtz NVEJ, Jannink LM, Gharu L, de Witte LD, Wensing AMJ, Lewin SR, Nijhuis M, Symons J. Shock and kill within the CNS: A promising HIV eradication approach? J Leukoc Biol 2022; 112:1297-1315. [PMID: 36148896 PMCID: PMC9826147 DOI: 10.1002/jlb.5vmr0122-046rrr] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Revised: 08/12/2022] [Accepted: 08/15/2022] [Indexed: 01/18/2023] Open
Abstract
The most studied HIV eradication approach is the "shock and kill" strategy, which aims to reactivate the latent reservoir by latency reversing agents (LRAs) and allowing elimination of these cells by immune-mediated clearance or viral cytopathic effects. The CNS is an anatomic compartment in which (persistent) HIV plays an important role in HIV-associated neurocognitive disorder. Restriction of the CNS by the blood-brain barrier is important for maintenance of homeostasis of the CNS microenvironment, which includes CNS-specific cell types, expression of transcription factors, and altered immune surveillance. Within the CNS predominantly myeloid cells such as microglia and perivascular macrophages are thought to be a reservoir of persistent HIV infection. Nevertheless, infection of T cells and astrocytes might also impact HIV infection in the CNS. Genetic adaptation to this microenvironment results in genetically distinct, compartmentalized viral populations with differences in transcription profiles. Because of these differences in transcription profiles, LRAs might have different effects within the CNS as compared with the periphery. Moreover, reactivation of HIV in the brain and elimination of cells within the CNS might be complex and could have detrimental consequences. Finally, independent of activity on latent HIV, LRAs themselves can have adverse neurologic effects. We provide an extensive overview of the current knowledge on compartmentalized (persistent) HIV infection in the CNS and on the "shock and kill" strategy. Subsequently, we reflect on the impact and promise of the "shock and kill" strategy on the elimination of persistent HIV in the CNS.
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Affiliation(s)
- Marieke M. Nühn
- Translational Virology, Department of Medical MicrobiologyUniversity Medical CenterUtrechtthe Netherlands
| | - Stephanie B. H. Gumbs
- Translational Virology, Department of Medical MicrobiologyUniversity Medical CenterUtrechtthe Netherlands
| | - Ninée V. E. J. Buchholtz
- Translational Virology, Department of Medical MicrobiologyUniversity Medical CenterUtrechtthe Netherlands
| | - Lisanne M. Jannink
- Translational Virology, Department of Medical MicrobiologyUniversity Medical CenterUtrechtthe Netherlands
| | - Lavina Gharu
- Translational Virology, Department of Medical MicrobiologyUniversity Medical CenterUtrechtthe Netherlands
| | - Lot D. de Witte
- Translational Virology, Department of Medical MicrobiologyUniversity Medical CenterUtrechtthe Netherlands,Department of PsychiatryIcahn School of MedicineNew YorkNew YorkUSA
| | - Annemarie M. J. Wensing
- Translational Virology, Department of Medical MicrobiologyUniversity Medical CenterUtrechtthe Netherlands
| | - Sharon R. Lewin
- Department of Infectious DiseasesThe University of Melbourne at the Peter Doherty Institute of Immunity and InfectionMelbourneVICAustralia,Victorian Infectious Diseases ServiceThe Royal Melbourne Hospital at the Peter Doherty Institute of Immunity and InfectionMelbourneVICAustralia,Department of Infectious DiseasesAlfred Hospital and Monash UniversityMelbourneVICAustralia
| | - Monique Nijhuis
- Translational Virology, Department of Medical MicrobiologyUniversity Medical CenterUtrechtthe Netherlands
| | - Jori Symons
- Translational Virology, Department of Medical MicrobiologyUniversity Medical CenterUtrechtthe Netherlands
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20
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Eid J, Socol M, Naillon A, Feuillard J, Ciandrini L, Margeat E, Charlot B, Mougel M. Viro-fluidics: Real-time analysis of virus production kinetics at the single-cell level. BIOPHYSICAL REPORTS 2022; 2:100068. [PMID: 36425325 PMCID: PMC9680794 DOI: 10.1016/j.bpr.2022.100068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Accepted: 08/05/2022] [Indexed: 06/16/2023]
Abstract
Real-time visualization and quantification of viruses released by a cell are crucial to further decipher infection processes. Kinetics studies at the single-cell level will circumvent the limitations of bulk assays with asynchronous virus replication. We have implemented a "viro-fluidic" method, which combines microfluidics and virology at single-cell and single-virus resolutions. As an experimental model, we used standard cell lines producing fluorescent HIV-like particles (VLPs). First, to scale the strategy to the single-cell level, we validated a sensitive flow virometry system to detect VLPs in low concentration samples (≥104 VLPs/mL). Then, this system was coupled to a single-cell trapping device to monitor in real-time the VLPs released, one at a time, from single cells under cell culture conditions. Our results revealed an average production rate of 50 VLPs/h/cell similar to the rate estimated for the same cells grown in population. Thus, the virus-producing capacities of the trapped cells were preserved and its real-time monitoring was accurate. Moreover, single-cell analysis revealed a release of VLPs with stochastic bursts with typical time intervals of few minutes, revealing the existence of limiting step(s) in the virus biogenesis process. Our tools can be applied to other pathogens or to extracellular vesicles to elucidate the dissemination mechanisms of these biological nanoparticles.
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Affiliation(s)
- Joëlle Eid
- Team R2D2: Retroviral RNA Dynamics and Delivery, IRIM, UMR9004, CNRS, University of Montpellier, Montpellier, France
| | - Marius Socol
- Team R2D2: Retroviral RNA Dynamics and Delivery, IRIM, UMR9004, CNRS, University of Montpellier, Montpellier, France
| | - Antoine Naillon
- Université Grenoble Alpes, CNRS, Grenoble INP, 3SR, Grenoble, France
| | - Jérôme Feuillard
- Team R2D2: Retroviral RNA Dynamics and Delivery, IRIM, UMR9004, CNRS, University of Montpellier, Montpellier, France
| | - Luca Ciandrini
- CBS, Université de Montpellier, CNRS, INSERM, Montpellier, France
| | - Emmanuel Margeat
- CBS, Université de Montpellier, CNRS, INSERM, Montpellier, France
| | - Benoit Charlot
- IES, Université de Montpellier, CNRS, Montpellier, France
| | - Marylène Mougel
- Team R2D2: Retroviral RNA Dynamics and Delivery, IRIM, UMR9004, CNRS, University of Montpellier, Montpellier, France
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21
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A transcriptional cycling model recapitulates chromatin-dependent features of noisy inducible transcription. PLoS Comput Biol 2022; 18:e1010152. [PMID: 36084132 PMCID: PMC9491597 DOI: 10.1371/journal.pcbi.1010152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 09/21/2022] [Accepted: 08/12/2022] [Indexed: 11/23/2022] Open
Abstract
Activation of gene expression in response to environmental cues results in substantial phenotypic heterogeneity between cells that can impact a wide range of outcomes including differentiation, viral activation, and drug resistance. An important source of gene expression noise is transcriptional bursting, or the process by which transcripts are produced during infrequent bursts of promoter activity. Chromatin accessibility impacts transcriptional bursting by regulating the assembly of transcription factor and polymerase complexes on promoters, suggesting that the effect of an activating signal on transcriptional noise will depend on the initial chromatin state at the promoter. To explore this possibility, we simulated transcriptional activation using a transcriptional cycling model with three promoter states that represent chromatin remodeling, polymerase binding and pause release. We initiated this model over a large parameter range representing target genes with different chromatin environments, and found that, upon increasing the polymerase pause release rate to activate transcription, changes in gene expression noise varied significantly across initial promoter states. This model captured phenotypic differences in activation of latent HIV viruses integrated at different chromatin locations and mediated by the transcription factor NF-κB. Activating transcription in the model via increasing one or more of the transcript production rates, as occurs following NF-κB activation, reproduced experimentally measured transcript distributions for four different latent HIV viruses, as well as the bimodal pattern of HIV protein expression that leads to a subset of reactivated virus. Importantly, the parameter ‘activation path’ differentially affected gene expression noise, and ultimately viral activation, in line with experimental observations. This work demonstrates how upstream signaling pathways can be connected to biological processes that underlie transcriptional bursting, resulting in target gene-specific noise profiles following stimulation of a single upstream pathway. Many genes are transcribed in infrequent bursts of mRNA production through a process called transcriptional bursting, which contributes to variability in responses between cells. Heterogeneity in cell responses can have important biological impacts, such as whether a cell supports viral replication or responds to a drug, and thus there is an effort to describe this process with mathematical models to predict biological outcomes. Previous models described bursting as a transition between an “OFF” state or an “ON” state, an elegant and simple mathematical representation of complex molecular mechanisms, but one which failed to capture how upstream activation signals affected bursting. To address this, we added an additional promoter state to better reflect biological mechanisms underlying bursting. By fitting this model to variable activation of quiescent HIV infections in T cells, we showed that our model more accurately described viral expression variability across cells in response to an upstream stimulus. Our work highlights how mathematical models can be further developed to understand complex biological mechanisms and suggests ways to connect transcriptional bursting to upstream activation pathways.
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22
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Kuniholm J, Coote C, Henderson AJ. Defective HIV-1 genomes and their potential impact on HIV pathogenesis. Retrovirology 2022; 19:13. [PMID: 35764966 PMCID: PMC9238239 DOI: 10.1186/s12977-022-00601-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Accepted: 06/17/2022] [Indexed: 11/28/2022] Open
Abstract
Defective HIV-1 proviruses represent a population of viral genomes that are selected for by immune pressures, and clonally expanded to dominate the persistent HIV-1 proviral genome landscape. There are examples of RNA and protein expression from these compromised genomes which are generated by a variety of mechanisms. Despite the evidence that these proviruses are transcribed and translated, their role in HIV pathogenesis has not been fully explored. The potential for these genomes to participate in immune stimulation is particularly relevant considering the accumulation of cells harboring these defective proviruses over the course of antiretroviral therapy in people living with HIV. The expression of defective proviruses in different cells and tissues could drive innate sensing mechanisms and inflammation. They may also alter antiviral T cell responses and myeloid cell functions that directly contribute to HIV-1 associated chronic comorbidities. Understanding the impact of these defective proviruses needs to be considered as we advance cure strategies that focus on targeting the diverse population of HIV-1 proviral genomes.
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Affiliation(s)
- Jeffrey Kuniholm
- Department of Microbiology, Section of Infectious Diseases, Boston University School of Medicine, Boston, MA, 02116, USA
| | - Carolyn Coote
- Department of Medicine, Section of Infectious Diseases, Boston University School of Medicine, Boston, MA, 02116, USA
| | - Andrew J Henderson
- Department of Microbiology, Section of Infectious Diseases, Boston University School of Medicine, Boston, MA, 02116, USA. .,Department of Medicine, Section of Infectious Diseases, Boston University School of Medicine, Boston, MA, 02116, USA.
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23
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van Heuvel Y, Schatz S, Rosengarten JF, Stitz J. Infectious RNA: Human Immunodeficiency Virus (HIV) Biology, Therapeutic Intervention, and the Quest for a Vaccine. Toxins (Basel) 2022; 14:toxins14020138. [PMID: 35202165 PMCID: PMC8876946 DOI: 10.3390/toxins14020138] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 02/02/2022] [Accepted: 02/09/2022] [Indexed: 11/16/2022] Open
Abstract
Different mechanisms mediate the toxicity of RNA. Genomic retroviral mRNA hijacks infected host cell factors to enable virus replication. The viral genomic RNA of the human immunodeficiency virus (HIV) encompasses nine genes encoding in less than 10 kb all proteins needed for replication in susceptible host cells. To do so, the genomic RNA undergoes complex alternative splicing to facilitate the synthesis of the structural, accessory, and regulatory proteins. However, HIV strongly relies on the host cell machinery recruiting cellular factors to complete its replication cycle. Antiretroviral therapy (ART) targets different steps in the cycle, preventing disease progression to the acquired immunodeficiency syndrome (AIDS). The comprehension of the host immune system interaction with the virus has fostered the development of a variety of vaccine platforms. Despite encouraging provisional results in vaccine trials, no effective vaccine has been developed, yet. However, novel promising vaccine platforms are currently under investigation.
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Affiliation(s)
- Yasemin van Heuvel
- Research Group Pharmaceutical Biotechnology, Faculty of Applied Natural Sciences, TH Köln—University of Applied Sciences, Chempark Leverkusen, Kaiser-Wilhelm-Allee, 51368 Leverkusen, Germany; (Y.v.H.); (S.S.); (J.F.R.)
- Institute of Technical Chemistry, Leibniz University Hannover, Callinstraße 3-9, 30167 Hannover, Germany
| | - Stefanie Schatz
- Research Group Pharmaceutical Biotechnology, Faculty of Applied Natural Sciences, TH Köln—University of Applied Sciences, Chempark Leverkusen, Kaiser-Wilhelm-Allee, 51368 Leverkusen, Germany; (Y.v.H.); (S.S.); (J.F.R.)
- Institute of Technical Chemistry, Leibniz University Hannover, Callinstraße 3-9, 30167 Hannover, Germany
| | - Jamila Franca Rosengarten
- Research Group Pharmaceutical Biotechnology, Faculty of Applied Natural Sciences, TH Köln—University of Applied Sciences, Chempark Leverkusen, Kaiser-Wilhelm-Allee, 51368 Leverkusen, Germany; (Y.v.H.); (S.S.); (J.F.R.)
- Institute of Technical Chemistry, Leibniz University Hannover, Callinstraße 3-9, 30167 Hannover, Germany
| | - Jörn Stitz
- Research Group Pharmaceutical Biotechnology, Faculty of Applied Natural Sciences, TH Köln—University of Applied Sciences, Chempark Leverkusen, Kaiser-Wilhelm-Allee, 51368 Leverkusen, Germany; (Y.v.H.); (S.S.); (J.F.R.)
- Correspondence:
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24
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Yang X, Luo S, Zhang Z, Wang Z, Zhou T, Zhang J. Silent transcription intervals and translational bursting lead to diverse phenotypic switching. Phys Chem Chem Phys 2022; 24:26600-26608. [DOI: 10.1039/d2cp03703c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
For complex process of gene expression, we use theoretical analysis and stochastic simulations to study the phenotypic diversity induced by silent transcription intervals and translational bursting.
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Affiliation(s)
- Xiyan Yang
- School of Financial Mathematics and Statistics, Guangdong University of Finance, Guangzhou 510521, P. R. China
| | - Songhao Luo
- School of Mathematics, Sun Yat-Sen University, Guangzhou 510275, P. R. China
- Guangdong Province Key Laboratory of Computational Science, Guangzhou 510275, P. R. China
| | - Zhenquan Zhang
- School of Mathematics, Sun Yat-Sen University, Guangzhou 510275, P. R. China
- Guangdong Province Key Laboratory of Computational Science, Guangzhou 510275, P. R. China
| | - Zihao Wang
- School of Mathematics, Sun Yat-Sen University, Guangzhou 510275, P. R. China
- Guangdong Province Key Laboratory of Computational Science, Guangzhou 510275, P. R. China
| | - Tianshou Zhou
- School of Mathematics, Sun Yat-Sen University, Guangzhou 510275, P. R. China
- Guangdong Province Key Laboratory of Computational Science, Guangzhou 510275, P. R. China
| | - Jiajun Zhang
- School of Mathematics, Sun Yat-Sen University, Guangzhou 510275, P. R. China
- Guangdong Province Key Laboratory of Computational Science, Guangzhou 510275, P. R. China
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25
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Abstract
To identify novel host factors as putative targets to reverse HIV-1 latency, we performed an insertional mutagenesis genetic screen in a latent HIV-1 infected pseudohaploid KBM7 cell line (Hap-Lat). Following mutagenesis, insertions were mapped to the genome, and bioinformatic analysis resulted in the identification of 69 candidate host genes involved in maintaining HIV-1 latency. A select set of candidate genes was functionally validated using short hairpin RNA (shRNA)-mediated depletion in latent HIV-1 infected J-Lat A2 and 11.1 T cell lines. We confirmed ADK, CHD9, CMSS1, EVI2B, EXOSC8, FAM19A, GRIK5, IRF2BP2, NF1, and USP15 as novel host factors involved in the maintenance of HIV-1 latency. Chromatin immunoprecipitation assays indicated that CHD9, a chromodomain helicase DNA-binding protein, maintains HIV-1 latency via direct association with the HIV-1 5′ long terminal repeat (LTR), and its depletion results in increased histone acetylation at the HIV-1 promoter, concomitant with HIV-1 latency reversal. FDA-approved inhibitors 5-iodotubercidin, trametinib, and topiramate, targeting ADK, NF1, and GRIK5, respectively, were characterized for their latency reversal potential. While 5-iodotubercidin exhibited significant cytotoxicity in both J-Lat and primary CD4+ T cells, trametinib reversed latency in J-Lat cells but not in latent HIV-1 infected primary CD4+ T cells. Importantly, topiramate reversed latency in cell line models, in latently infected primary CD4+ T cells, and crucially in CD4+ T cells from three people living with HIV-1 (PLWH) under suppressive antiretroviral therapy, without inducing T cell activation or significant toxicity. Thus, using an adaptation of a haploid forward genetic screen, we identified novel and druggable host factors contributing to HIV-1 latency.
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26
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Acchioni C, Palermo E, Sandini S, Acchioni M, Hiscott J, Sgarbanti M. Fighting HIV-1 Persistence: At the Crossroads of "Shoc-K and B-Lock". Pathogens 2021; 10:pathogens10111517. [PMID: 34832672 PMCID: PMC8622007 DOI: 10.3390/pathogens10111517] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Revised: 11/10/2021] [Accepted: 11/17/2021] [Indexed: 12/12/2022] Open
Abstract
Despite the success of highly active antiretroviral therapy (HAART), integrated HIV-1 proviral DNA cannot be eradicated from an infected individual. HAART is not able to eliminate latently infected cells that remain invisible to the immune system. Viral sanctuaries in specific tissues and immune-privileged sites may cause residual viral replication that contributes to HIV-1 persistence. The “Shock or Kick, and Kill” approach uses latency reversing agents (LRAs) in the presence of HAART, followed by cell-killing due to viral cytopathic effects and immune-mediated clearance. Different LRAs may be required for the in vivo reactivation of HIV-1 in different CD4+ T cell reservoirs, leading to the activation of cellular transcription factors acting on the integrated proviral HIV-1 LTR. An important requirement for LRA drugs is the reactivation of viral transcription and replication without causing a generalized immune activation. Toll-like receptors, RIG-I like receptors, and STING agonists have emerged recently as a new class of LRAs that augment selective apoptosis in reactivated T lymphocytes. The challenge is to extend in vitro observations to HIV-1 positive patients. Further studies are also needed to overcome the mechanisms that protect latently infected cells from reactivation and/or elimination by the immune system. The Block and Lock alternative strategy aims at using latency promoting/inducing agents (LPAs/LIAs) to block the ability of latent proviruses to reactivate transcription in order to achieve a long term lock down of potential residual virus replication. The Shock and Kill and the Block and Lock approaches may not be only alternative to each other, but, if combined together (one after the other), or given all at once [namely “Shoc-K(kill) and B(block)-Lock”], they may represent a better approach to a functional cure.
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Affiliation(s)
- Chiara Acchioni
- Department of Infectious Diseases, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy; (C.A.); (S.S.); (M.A.)
| | - Enrico Palermo
- Istituto Pasteur Italia—Cenci Bolognetti Foundation, Viale Regina Elena 291, 00161 Rome, Italy; (E.P.); (J.H.)
| | - Silvia Sandini
- Department of Infectious Diseases, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy; (C.A.); (S.S.); (M.A.)
| | - Marta Acchioni
- Department of Infectious Diseases, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy; (C.A.); (S.S.); (M.A.)
| | - John Hiscott
- Istituto Pasteur Italia—Cenci Bolognetti Foundation, Viale Regina Elena 291, 00161 Rome, Italy; (E.P.); (J.H.)
| | - Marco Sgarbanti
- Department of Infectious Diseases, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy; (C.A.); (S.S.); (M.A.)
- Correspondence: ; Tel.: +39-06-4990-3266
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27
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Coffin JM, Hughes SH. Clonal Expansion of Infected CD4+ T Cells in People Living with HIV. Viruses 2021; 13:v13102078. [PMID: 34696507 PMCID: PMC8537114 DOI: 10.3390/v13102078] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Revised: 09/28/2021] [Accepted: 10/05/2021] [Indexed: 01/16/2023] Open
Abstract
HIV infection is not curable with current antiretroviral therapy (ART) because a small fraction of CD4+ T cells infected prior to ART initiation persists. Understanding the nature of this latent reservoir and how it is created is essential to development of potentially curative strategies. The discovery that a large fraction of the persistently infected cells in individuals on suppressive ART are members of large clones greatly changed our view of the reservoir and how it arises. Rather than being the products of infection of resting cells, as was once thought, HIV persistence is largely or entirely a consequence of infection of cells that are either expanding or are destined to expand, primarily due to antigen-driven activation. Although most of the clones carry defective proviruses, some carry intact infectious proviruses; these clones comprise the majority of the reservoir. A large majority of both the defective and the intact infectious proviruses in clones of infected cells are transcriptionally silent; however, a small fraction expresses a few copies of unspliced HIV RNA. A much smaller fraction is responsible for production of low levels of infectious virus, which can rekindle infection when ART is stopped. Further understanding of the reservoir will be needed to clarify the mechanism(s) by which provirus expression is controlled in the clones of cells that constitute the reservoir.
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Affiliation(s)
- John M. Coffin
- Department of Molecular Biology and Microbiology, Tufts University, Boston, MA 02111, USA;
| | - Stephen H. Hughes
- HIV Dynamics and Replication Program, National Cancer Institute in Frederick, Frederick, MD 21702, USA
- Correspondence:
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28
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Braichenko S, Holehouse J, Grima R. Distinguishing between models of mammalian gene expression: telegraph-like models versus mechanistic models. J R Soc Interface 2021; 18:20210510. [PMID: 34610262 PMCID: PMC8492181 DOI: 10.1098/rsif.2021.0510] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Two-state models (telegraph-like models) have a successful history of predicting distributions of cellular and nascent mRNA numbers that can well fit experimental data. These models exclude key rate limiting steps, and hence it is unclear why they are able to accurately predict the number distributions. To answer this question, here we compare these models to a novel stochastic mechanistic model of transcription in mammalian cells that presents a unified description of transcriptional factor, polymerase and mature mRNA dynamics. We show that there is a large region of parameter space where the first, second and third moments of the distributions of the waiting times between two consecutively produced transcripts (nascent or mature) of two-state and mechanistic models exactly match. In this region: (i) one can uniquely express the two-state model parameters in terms of those of the mechanistic model, (ii) the models are practically indistinguishable by comparison of their transcript numbers distributions, and (iii) they are distinguishable from the shape of their waiting time distributions. Our results clarify the relationship between different gene expression models and identify a means to select between them from experimental data.
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Affiliation(s)
- Svitlana Braichenko
- School of Biological Sciences, University of Edinburgh, Edinburgh, UK.,School of Informatics, University of Edinburgh, Edinburgh, UK
| | - James Holehouse
- School of Biological Sciences, University of Edinburgh, Edinburgh, UK
| | - Ramon Grima
- School of Biological Sciences, University of Edinburgh, Edinburgh, UK
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29
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Pimmett VL, Dejean M, Fernandez C, Trullo A, Bertrand E, Radulescu O, Lagha M. Quantitative imaging of transcription in living Drosophila embryos reveals the impact of core promoter motifs on promoter state dynamics. Nat Commun 2021; 12:4504. [PMID: 34301936 PMCID: PMC8302612 DOI: 10.1038/s41467-021-24461-6] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Accepted: 03/31/2021] [Indexed: 11/09/2022] Open
Abstract
Genes are expressed in stochastic transcriptional bursts linked to alternating active and inactive promoter states. A major challenge in transcription is understanding how promoter composition dictates bursting, particularly in multicellular organisms. We investigate two key Drosophila developmental promoter motifs, the TATA box (TATA) and the Initiator (INR). Using live imaging in Drosophila embryos and new computational methods, we demonstrate that bursting occurs on multiple timescales ranging from seconds to minutes. TATA-containing promoters and INR-containing promoters exhibit distinct dynamics, with one or two separate rate-limiting steps respectively. A TATA box is associated with long active states, high rates of polymerase initiation, and short-lived, infrequent inactive states. In contrast, the INR motif leads to two inactive states, one of which relates to promoter-proximal polymerase pausing. Surprisingly, the model suggests pausing is not obligatory, but occurs stochastically for a subset of polymerases. Overall, our results provide a rationale for promoter switching during zygotic genome activation.
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Affiliation(s)
- Virginia L Pimmett
- Institut de Génétique Moléculaire de Montpellier, Univ Montpellier, CNRS, Montpellier, France
| | - Matthieu Dejean
- Institut de Génétique Moléculaire de Montpellier, Univ Montpellier, CNRS, Montpellier, France
| | - Carola Fernandez
- Institut de Génétique Moléculaire de Montpellier, Univ Montpellier, CNRS, Montpellier, France
| | - Antonio Trullo
- Institut de Génétique Moléculaire de Montpellier, Univ Montpellier, CNRS, Montpellier, France
| | - Edouard Bertrand
- Institut de Génétique Moléculaire de Montpellier, Univ Montpellier, CNRS, Montpellier, France
- Institut de Génétique Humaine, Univ Montpellier, CNRS, Montpellier, France
| | - Ovidiu Radulescu
- Laboratory of Pathogen Host Interactions, Univ Montpellier, CNRS, Montpellier, France
| | - Mounia Lagha
- Institut de Génétique Moléculaire de Montpellier, Univ Montpellier, CNRS, Montpellier, France.
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