1
|
Keown J, Baazaoui A, Šebesta M, Štefl R, Carrique L, Fodor E, Grimes JM. Structural and functional characterization of the interaction between the influenza A virus RNA polymerase and the CTD of host RNA polymerase II. J Virol 2024; 98:e0013824. [PMID: 38563748 PMCID: PMC11092357 DOI: 10.1128/jvi.00138-24] [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: 01/19/2024] [Accepted: 03/10/2024] [Indexed: 04/04/2024] Open
Abstract
Influenza A viruses, causing seasonal epidemics and occasional pandemics, rely on interactions with host proteins for their RNA genome transcription and replication. The viral RNA polymerase utilizes host RNA polymerase II (Pol II) and interacts with the serine 5 phosphorylated (pS5) C-terminal domain (CTD) of Pol II to initiate transcription. Our study, using single-particle electron cryomicroscopy (cryo-EM), reveals the structure of the 1918 pandemic influenza A virus polymerase bound to a synthetic pS5 CTD peptide composed of four heptad repeats mimicking the 52 heptad repeat mammalian Pol II CTD. The structure shows that the CTD peptide binds at the C-terminal domain of the PA viral polymerase subunit (PA-C) and reveals a previously unobserved position of the 627 domain of the PB2 subunit near the CTD. We identify crucial residues of the CTD peptide that mediate interactions with positively charged cavities on PA-C, explaining the preference of the viral polymerase for pS5 CTD. Functional analysis of mutants targeting the CTD-binding site within PA-C reveals reduced transcriptional function or defects in replication, highlighting the multifunctional role of PA-C in viral RNA synthesis. Our study provides insights into the structural and functional aspects of the influenza virus polymerase-host Pol II interaction and identifies a target for antiviral development.IMPORTANCEUnderstanding the intricate interactions between influenza A viruses and host proteins is crucial for developing targeted antiviral strategies. This study employs advanced imaging techniques to uncover the structural nuances of the 1918 pandemic influenza A virus polymerase bound to a specific host protein, shedding light on the vital process of viral RNA synthesis. The study identifies key amino acid residues in the influenza polymerase involved in binding host polymerase II (Pol II) and highlights their role in both viral transcription and genome replication. These findings not only deepen our understanding of the influenza virus life cycle but also pinpoint a potential target for antiviral development. By elucidating the structural and functional aspects of the influenza virus polymerase-host Pol II interaction, this research provides a foundation for designing interventions to disrupt viral replication and transcription, offering promising avenues for future antiviral therapies.
Collapse
Affiliation(s)
- Jeremy Keown
- Division of Structural Biology, Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Alaa Baazaoui
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Marek Šebesta
- CEITEC–Central European Institute of Technology, Masaryk University, Brno, Czechia
| | - Richard Štefl
- CEITEC–Central European Institute of Technology, Masaryk University, Brno, Czechia
- National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Brno, Czechia
| | - Loïc Carrique
- Division of Structural Biology, Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Ervin Fodor
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Jonathan M. Grimes
- Division of Structural Biology, Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| |
Collapse
|
2
|
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.
Collapse
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.
| |
Collapse
|
3
|
Archuleta SR, Goodrich JA, Kugel JF. Mechanisms and Functions of the RNA Polymerase II General Transcription Machinery during the Transcription Cycle. Biomolecules 2024; 14:176. [PMID: 38397413 PMCID: PMC10886972 DOI: 10.3390/biom14020176] [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: 12/21/2023] [Revised: 01/29/2024] [Accepted: 01/30/2024] [Indexed: 02/25/2024] Open
Abstract
Central to the development and survival of all organisms is the regulation of gene expression, which begins with the process of transcription catalyzed by RNA polymerases. During transcription of protein-coding genes, the general transcription factors (GTFs) work alongside RNA polymerase II (Pol II) to assemble the preinitiation complex at the transcription start site, open the promoter DNA, initiate synthesis of the nascent messenger RNA, transition to productive elongation, and ultimately terminate transcription. Through these different stages of transcription, Pol II is dynamically phosphorylated at the C-terminal tail of its largest subunit, serving as a control mechanism for Pol II elongation and a signaling/binding platform for co-transcriptional factors. The large number of core protein factors participating in the fundamental steps of transcription add dense layers of regulation that contribute to the complexity of temporal and spatial control of gene expression within any given cell type. The Pol II transcription system is highly conserved across different levels of eukaryotes; however, most of the information here will focus on the human Pol II system. This review walks through various stages of transcription, from preinitiation complex assembly to termination, highlighting the functions and mechanisms of the core machinery that participates in each stage.
Collapse
Affiliation(s)
| | - James A. Goodrich
- Department of Biochemistry, University of Colorado Boulder, 596 UCB, Boulder, CO 80309, USA;
| | - Jennifer F. Kugel
- Department of Biochemistry, University of Colorado Boulder, 596 UCB, Boulder, CO 80309, USA;
| |
Collapse
|
4
|
Huang L, Yang H, Chen K, Yuan J, Li J, Dai G, Gu M, Shi Y. The suppressive efficacy of THZ1 depends on KRAS mutation subtype and is associated with super-enhancer activity and the PI3K/AKT/mTOR signalling in pancreatic ductal adenocarcinoma: A hypothesis-generating study. Clin Transl Med 2023; 13:e1500. [PMID: 38037549 PMCID: PMC10689978 DOI: 10.1002/ctm2.1500] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2023] [Revised: 10/24/2023] [Accepted: 11/17/2023] [Indexed: 12/02/2023] Open
Abstract
BACKGROUND Inhibition of CDK7, a potent transcription regulator, may bring new hope for treating pancreatic ductal adenocarcinoma (PDAC), which is featured by large genetic heterogeneity and abundant KRAS mutations. This investigation aimed at exploring the discrepant efficacies of THZ1, a small-molecule covalent CDK7 inhibitor, on PDACs with different KRAS mutations and the underlying mechanisms. METHODS Associations of CDK7 expression with survival by KRAS mutations were first assessed. Effects of THZ1 on PDAC by different KRAS mutations were then investigated in vitro and in vivo. Moreover, the effects of THZ1 on gene transcription and phosphorylation of RNA polymerase II (RNAPOLII) in different KRAS mutant PDACs were assessed, and the effect of THZ1 on super-enhancer activity was evaluated using chromatin immunoprecipitation sequencing. Lastly, the effects of THZ1 on the binding of H3K27ac to PIK3CA and on the PI3K/AKT/mTOR signalling were analysed. RESULTS High CDK7 expression was significantly linked to worse survival within PDAC patients carrying KRAS-G12V mutation but not in those with KRAS-G12D mutation. The apoptosis-inducing effect of THZ1 was markedly stronger in KRAS-G12V PDAC than KRAS-G12D cancer. THZ1 significantly inhibited the growth of xenograft tumour with KRAS-G12V mutation, and the inhibition was markedly stronger than for KRAS-G12D tumour. In mini-cell-derived xenograft (CDX) models, THZ1 significantly suppressed KRAS-G12V PDAC but not KRAS-G12D cancer. THZ1 significantly suppressed the phosphorylation of RNAPOLII, and this effect was stronger in KRAS-G12V PDAC (especially at ser5). KRAS-G12V PDAC had more H3K27ac-binding super-enhancers, and the inhibition of THZ1 on super-enhancer activity was also stronger in KRAS-G12V PDAC. Furthermore, THZ1 significantly weakened the binding of H3K27ac to PIK3CA in KRAS-G12V PDAC. THZ1 significantly suppressed the PI3K/AKT/mTOR pathway and its downstream markers, and this effect was stronger in KRAS-G12V cells. CONCLUSIONS In this hypothesis-generating study, THZ1 might selectively inhibit certain PDACs with KRAS-G12V mutation more potently compared with some other PDACs with KRAS-G12D mutation, which might be associated with its effect on super-enhancer activity and the PI3K/AKT/mTOR signalling. Our findings might offer novel key clues for the precise management of PDAC and important evidence for future targeted trial design. HIGHLIGHTS THZ1 had a stronger effect on PDAC-bearing KRAS-G12V mutation than G12D mutation. Suppressive effect of THZ1 on phosphorylation of RNAPOLII was stronger in KRAS-G12V than KRAS-G12D PDAC. Inhibition of THZ1 on super-enhancer activity and H3K27ac binding to PIK3CA was stronger in KRAS-G12V PDAC. Suppressive effect of THZ1 on PI3K/AKT/mTOR pathway was stronger in KRAS-G12V PDAC.
Collapse
Affiliation(s)
- Lei Huang
- Department of OncologyRuijin HospitalShanghai Jiao Tong University School of MedicineShanghaiChina
| | - Hui Yang
- Department of OncologyRuijin HospitalShanghai Jiao Tong University School of MedicineShanghaiChina
| | - Kaidi Chen
- School of Pharmaceutical ScienceZhejiang Chinese Medical UniversityHangzhouChina
| | - Jing Yuan
- Department of PathologyChinese PLA General HospitalBeijingChina
| | - Jie Li
- Department of PathologyChinese PLA General HospitalBeijingChina
| | - Guanghai Dai
- Department of Medical OncologyChinese PLA General HospitalBeijingChina
| | - Mancang Gu
- School of Pharmaceutical ScienceZhejiang Chinese Medical UniversityHangzhouChina
- Academy of Chinese Medical SciencesZhejiang Chinese Medical UniversityHangzhouChina
| | - Yan Shi
- Department of General SurgeryShanghai Seventh People's HospitalShanghai University of Traditional Chinese MedicineShanghaiChina
| |
Collapse
|
5
|
Bihani A, Avvaru AK, Mishra RK. Biochemical Deconstruction and Reconstruction of Nuclear Matrix Reveals the Layers of Nuclear Organization. Mol Cell Proteomics 2023; 22:100671. [PMID: 37863319 PMCID: PMC10687341 DOI: 10.1016/j.mcpro.2023.100671] [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: 08/30/2023] [Revised: 10/11/2023] [Accepted: 10/15/2023] [Indexed: 10/22/2023] Open
Abstract
Nuclear matrix (NuMat) is the fraction of the eukaryotic nucleus insoluble to detergents and high-salt extractions that manifests as a pan-nuclear fiber-granule network. NuMat consists of ribonucleoprotein complexes, members of crucial nuclear functional modules, and DNA fragments. Although NuMat captures the organization of nonchromatin nuclear space, very little is known about components organization within NuMat. To understand the organization of NuMat components, we subfractionated it with increasing concentrations of the chaotrope guanidinium hydrochloride (GdnHCl) and analyzed the proteomic makeup of the fractions. We observe that the solubilization of proteins at different concentrations of GdnHCl is finite and independent of the broad biophysical properties of the protein sequences. Looking at the extraction pattern of the nuclear envelope and nuclear pore complex, we surmise that this fractionation represents easily solubilized/loosely bound and difficultly solubilized/tightly bound components of NuMat. Microscopic analyses of the localization of key NuMat proteins across sequential GdnHCl extractions of in situ NuMat further elaborate on the divergent extraction patterns. Furthermore, we solubilized NuMat in 8M GdnHCl and upon removal of GdnHCl through dialysis, en masse renaturation leads to RNA-dependent self-assembly of fibrous structures. The major proteome component of the self-assembled fibers comes from the difficultly solubilized, tightly bound component. This fractionation of the NuMat reveals different organizational levels within it which may reflect the structural and functional organization of nuclear architecture.
Collapse
Affiliation(s)
- Ashish Bihani
- CSIR - Centre for Cellular and Molecular Biology (CCMB), Hyderabad, India.
| | - Akshay K Avvaru
- CSIR - Centre for Cellular and Molecular Biology (CCMB), Hyderabad, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
| | - Rakesh K Mishra
- CSIR - Centre for Cellular and Molecular Biology (CCMB), Hyderabad, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India; Tata Institute for Genetics and Society (TIGS), Bengaluru, India.
| |
Collapse
|
6
|
Platz KR, Rudisel EJ, Paluch KV, Laurin TR, Dittenhafer-Reed KE. Assessing the Role of Post-Translational Modifications of Mitochondrial RNA Polymerase. Int J Mol Sci 2023; 24:16050. [PMID: 38003238 PMCID: PMC10671485 DOI: 10.3390/ijms242216050] [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: 10/10/2023] [Revised: 11/02/2023] [Accepted: 11/02/2023] [Indexed: 11/26/2023] Open
Abstract
The mitochondrial proteome is subject to abundant post-translational modifications, including lysine acetylation and phosphorylation of serine, threonine, and tyrosine. The biological function of the majority of these protein modifications is unknown. Proteins required for the transcription and translation of mitochondrial DNA (mtDNA) are subject to modification. This suggests that reversible post-translational modifications may serve as a regulatory mechanism for mitochondrial gene transcription, akin to mechanisms controlling nuclear gene expression. We set out to determine whether acetylation or phosphorylation controls the function of mitochondrial RNA polymerase (POLRMT). Mass spectrometry was used to identify post-translational modifications on POLRMT. We analyzed three POLRMT modification sites (lysine 402, threonine 315, threonine 993) found in distinct structural regions. Amino acid point mutants that mimic the modified and unmodified forms of POLRMT were employed to measure the effect of acetylation or phosphorylation on the promoter binding ability of POLRMT in vitro. We found a slight decrease in binding affinity for the phosphomimic at threonine 315. We did not identify large changes in viability, mtDNA content, or mitochondrial transcript level upon overexpression of POLRMT modification mimics in HeLa cells. Our results suggest minimal biological impact of the POLRMT post-translational modifications studied in our system.
Collapse
|
7
|
Kasiliauskaite A, Kubicek K, Klumpler T, Zanova M, Zapletal D, Koutna E, Novacek J, Stefl R. Cooperation between intrinsically disordered and ordered regions of Spt6 regulates nucleosome and Pol II CTD binding, and nucleosome assembly. Nucleic Acids Res 2022; 50:5961-5973. [PMID: 35640611 PMCID: PMC9177984 DOI: 10.1093/nar/gkac451] [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: 04/15/2021] [Revised: 04/29/2022] [Accepted: 05/16/2022] [Indexed: 11/14/2022] Open
Abstract
Transcription elongation factor Spt6 associates with RNA polymerase II (Pol II) and acts as a histone chaperone, which promotes the reassembly of nucleosomes following the passage of Pol II. The precise mechanism of nucleosome reassembly mediated by Spt6 remains unclear. In this study, we used a hybrid approach combining cryo-electron microscopy and small-angle X-ray scattering to visualize the architecture of Spt6 from Saccharomyces cerevisiae. The reconstructed overall architecture of Spt6 reveals not only the core of Spt6, but also its flexible N- and C-termini, which are critical for Spt6's function. We found that the acidic N-terminal region of Spt6 prevents the binding of Spt6 not only to the Pol II CTD and Pol II CTD-linker, but also to pre-formed intact nucleosomes and nucleosomal DNA. The N-terminal region of Spt6 self-associates with the tSH2 domain and the core of Spt6 and thus controls binding to Pol II and nucleosomes. Furthermore, we found that Spt6 promotes the assembly of nucleosomes in vitro. These data indicate that the cooperation between the intrinsically disordered and structured regions of Spt6 regulates nucleosome and Pol II CTD binding, and also nucleosome assembly.
Collapse
Affiliation(s)
- Aiste Kasiliauskaite
- CEITEC-Central European Institute of Technology, Masaryk University, Brno CZ-62500, Czech Republic.,National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Brno CZ-62500, Czech Republic
| | - Karel Kubicek
- CEITEC-Central European Institute of Technology, Masaryk University, Brno CZ-62500, Czech Republic.,Department of Condensed Matter Physics, Faculty of Science, Masaryk University, Brno CZ-61137, Czech Republic
| | - Tomas Klumpler
- CEITEC-Central European Institute of Technology, Masaryk University, Brno CZ-62500, Czech Republic
| | - Martina Zanova
- CEITEC-Central European Institute of Technology, Masaryk University, Brno CZ-62500, Czech Republic.,Department of Condensed Matter Physics, Faculty of Science, Masaryk University, Brno CZ-61137, Czech Republic
| | - David Zapletal
- CEITEC-Central European Institute of Technology, Masaryk University, Brno CZ-62500, Czech Republic.,National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Brno CZ-62500, Czech Republic
| | - Eliska Koutna
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Prague, Czech Republic.,Department of Cell Biology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Jiri Novacek
- CEITEC-Central European Institute of Technology, Masaryk University, Brno CZ-62500, Czech Republic
| | - Richard Stefl
- CEITEC-Central European Institute of Technology, Masaryk University, Brno CZ-62500, Czech Republic.,National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Brno CZ-62500, Czech Republic
| |
Collapse
|
8
|
Ran Y, Huang S, Shi J, Feng Q, Deng Y, Xiang AP, Yao C. CFIm25 regulates human stem cell function independently of its role in mRNA alternative polyadenylation. RNA Biol 2022; 19:686-702. [PMID: 35491945 PMCID: PMC9067535 DOI: 10.1080/15476286.2022.2071025] [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] [Indexed: 11/29/2022] Open
Abstract
It has recently been shown that CFIm25, a canonical mRNA 3’ processing factor, could play a variety of physiological roles through its molecular function in the regulation of mRNA alternative polyadenylation (APA). Here, we used CRISPR/Cas9-mediated gene editing approach in human embryonic stem cells (hESCs) for CFIm25, and obtained three gene knockdown/mutant cell lines. CFIm25 gene editing resulted in higher proliferation rate and impaired differentiation potential for hESCs, with these effects likely to be directly regulated by the target genes, including the pluripotency factor rex1. Mechanistically, we unexpected found that perturbation in CFIm25 gene expression did not significantly affect cellular mRNA 3’ processing efficiency and APA profile. Rather, we provided evidences that CFIm25 may impact RNA polymerase II (RNAPII) occupancy at the body of transcribed genes, and promote the expression level of a group of transcripts associated with cellular proliferation and/or differentiation. Taken together, these results reveal novel mechanisms underlying CFIm25ʹs modulation in determination of cell fate, and provide evidence that the process of mammalian gene transcription may be regulated by an mRNA 3’ processing factor.
Collapse
Affiliation(s)
- Yi Ran
- Center for Stem Cell Biology and Tissue Engineering, Key Laboratory for Stem Cells and Tissue Engineering, Ministry of Education, Sun Yat-Sen University, Guangzhou, China
| | - Shanshan Huang
- Center for Stem Cell Biology and Tissue Engineering, Key Laboratory for Stem Cells and Tissue Engineering, Ministry of Education, Sun Yat-Sen University, Guangzhou, China
| | - Junjie Shi
- Center for Stem Cell Biology and Tissue Engineering, Key Laboratory for Stem Cells and Tissue Engineering, Ministry of Education, Sun Yat-Sen University, Guangzhou, China
| | - Qiumin Feng
- Center for Stem Cell Biology and Tissue Engineering, Key Laboratory for Stem Cells and Tissue Engineering, Ministry of Education, Sun Yat-Sen University, Guangzhou, China
| | - Yanhui Deng
- Center for Stem Cell Biology and Tissue Engineering, Key Laboratory for Stem Cells and Tissue Engineering, Ministry of Education, Sun Yat-Sen University, Guangzhou, China
| | - Andy Peng Xiang
- Center for Stem Cell Biology and Tissue Engineering, Key Laboratory for Stem Cells and Tissue Engineering, Ministry of Education, Sun Yat-Sen University, Guangzhou, China
| | - Chengguo Yao
- Center for Stem Cell Biology and Tissue Engineering, Key Laboratory for Stem Cells and Tissue Engineering, Ministry of Education, Sun Yat-Sen University, Guangzhou, China
- Department of Genetics and Cell Biology, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China
| |
Collapse
|
9
|
Rippe K, Papantonis A. Functional organization of RNA polymerase II in nuclear subcompartments. Curr Opin Cell Biol 2022; 74:88-96. [PMID: 35217398 DOI: 10.1016/j.ceb.2022.01.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 01/08/2022] [Accepted: 01/14/2022] [Indexed: 12/22/2022]
Abstract
Distinct clusters of RNA polymerase II are responsible for gene transcription inside eukaryotic cell nuclei. Despite the functional implications of such subnuclear organization, the attributes of these clusters and the mechanisms underlying their formation remain only partially understood. Recently, the concept of proteins and RNA phase-separating into liquid-like droplets was proposed to drive the formation of transcriptionally-active subcompartments. Here, we attempt to reconcile previous with more recent findings, and discuss how the different ways of assembling the active RNA polymerase II transcriptional machinery relate to nuclear compartmentalization.
Collapse
Affiliation(s)
- Karsten Rippe
- Division of Chromatin Networks, German Cancer Research Center (DKFZ) and Bioquant, Heidelberg, Germany.
| | - Argyris Papantonis
- Translational Epigenetics Group, Institute of Pathology, University Medical Center Göttingen, Göttingen, Germany.
| |
Collapse
|
10
|
Control of non-productive RNA polymerase II transcription via its early termination in metazoans. Biochem Soc Trans 2022; 50:283-295. [PMID: 35166324 DOI: 10.1042/bst20201140] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Revised: 01/11/2022] [Accepted: 01/24/2022] [Indexed: 11/17/2022]
Abstract
Transcription establishes the universal first step of gene expression where RNA is produced by a DNA-dependent RNA polymerase. The most versatile of eukaryotic RNA polymerases, RNA polymerase II (Pol II), transcribes a broad range of DNA including protein-coding and a variety of non-coding transcription units. Although Pol II can be configured as a durable enzyme capable of transcribing hundreds of kilobases, there is reliable evidence of widespread abortive Pol II transcription termination shortly after initiation, which is often followed by rapid degradation of the associated RNA. The molecular details underlying this phenomenon are still vague but likely reflect the action of quality control mechanisms on the early Pol II complex. Here, we summarize current knowledge of how and when such promoter-proximal quality control is asserted on metazoan Pol II.
Collapse
|
11
|
Transcription and chromatin-based surveillance mechanism controls suppression of cryptic antisense transcription. Cell Rep 2021; 36:109671. [PMID: 34496258 PMCID: PMC8441049 DOI: 10.1016/j.celrep.2021.109671] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 08/26/2020] [Accepted: 08/13/2021] [Indexed: 12/25/2022] Open
Abstract
Phosphorylation of the RNA polymerase II C-terminal domain Y1S2P3T4S5P6S7 consensus sequence coordinates key events during transcription, and its deregulation leads to defects in transcription and RNA processing. Here, we report that the histone deacetylase activity of the fission yeast Hos2/Set3 complex plays an important role in suppressing cryptic initiation of antisense transcription when RNA polymerase II phosphorylation is dysregulated due to the loss of Ssu72 phosphatase. Interestingly, although single Hos2 and Set3 mutants have little effect, loss of Hos2 or Set3 combined with ssu72Δ results in a synergistic increase in antisense transcription globally and correlates with elevated sensitivity to genotoxic agents. We demonstrate a key role for the Ssu72/Hos2/Set3 mechanism in the suppression of cryptic antisense transcription at the 3' end of convergent genes that are most susceptible to these defects, ensuring the fidelity of gene expression within dense genomes of simple eukaryotes.
Collapse
|
12
|
LeBlanc BM, Moreno RY, Escobar EE, Venkat Ramani MK, Brodbelt JS, Zhang Y. What's all the phos about? Insights into the phosphorylation state of the RNA polymerase II C-terminal domain via mass spectrometry. RSC Chem Biol 2021; 2:1084-1095. [PMID: 34458825 PMCID: PMC8341212 DOI: 10.1039/d1cb00083g] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2021] [Accepted: 06/03/2021] [Indexed: 12/31/2022] Open
Abstract
RNA polymerase II (RNAP II) is one of the primary enzymes responsible for expressing protein-encoding genes and some small nuclear RNAs. The enigmatic carboxy-terminal domain (CTD) of RNAP II and its phosphorylation state are critically important in regulating transcription in vivo. Early methods of identifying phosphorylation on the CTD heptad were plagued by issues of low specificity and ambiguous signals. However, advancements in the field of mass spectrometry (MS) have presented the opportunity to gain new insights into well-studied processes as well as explore new frontiers in transcription. By using MS, residues which are modified within the CTD heptad and across repeats are now able to be pinpointed. Likewise, identification of kinase and phosphatase specificity towards residues of the CTD has reached a new level of accuracy. Now, MS is being used to investigate the crosstalk between modified residues of the CTD and may be a critical technique for understanding how phosphorylation plays a role in the new LLPS model of transcription. Herein, we discuss the development of various MS techniques and evaluate their capabilities. By highlighting the pros and cons of each technique, we aim to provide future investigators with a comprehensive overview of how MS can be used to investigate the complexities of RNAP-II mediated transcription.
Collapse
Affiliation(s)
- Blase M LeBlanc
- Department of Molecular Biosciences, University of Texas Austin USA
| | - R Yvette Moreno
- Department of Molecular Biosciences, University of Texas Austin USA
| | | | | | | | - Yan Zhang
- Department of Molecular Biosciences, University of Texas Austin USA
- Institute of Cellular and Molecular Biology, University of Texas Austin USA
| |
Collapse
|
13
|
Sharma KL, Jia S, Beacon TH, Adewumi I, López C, Hu P, Xu W, Davie JR. Mitogen-induced transcriptional programming in human fibroblasts. Gene 2021; 800:145842. [PMID: 34274479 DOI: 10.1016/j.gene.2021.145842] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Accepted: 07/13/2021] [Indexed: 11/17/2022]
Abstract
Treatment of serum-starved quiescent human cells with fetal bovine serum (FBS), epidermal growth factor (EGF), or the phorbol ester (12-O-tetradecanoylphorbol-13-acetate, TPA) activates the RAS-MAPK pathway which initiates a transcriptional program which drives cells toward proliferation. Stimulation of the RAS-MAPK pathway activates mitogen- and stress-activated kinases (MSK) 1 and 2, which phosphorylate histone H3 at S10 (H3S10ph) or S28 (H3S28ph) (nucleosomal response) located at the regulatory regions of immediate-early genes, setting in motion a series of chromatin remodeling events that result in transcription initiation. To investigate immediate-early genes regulated by the MSK, we have completed transcriptome analyses (RNA sequencing) of human normal fibroblast cells (CCD-1070Sk) stimulated with EGF or TPA ± H89, a potent MSK/PKA inhibitor. The induction of many immediate-early genes was independent of MSK activity. However, the induction of immediate-early genes attenuated with H89 also had reduced induction with the PKA inhibitor, Rp-cAMPS. Several EGF-induced genes, coding for transcriptional repressors, were further upregulated with H89 but not with Rp-cAMPS, suggesting a role for MSK in modulating the induction level of these genes.
Collapse
Affiliation(s)
- Kiran L Sharma
- Department of Biochemistry and Medical Genetics, University of Manitoba, Winnipeg, Manitoba R3E 0J9, Canada
| | - Shuo Jia
- Department of Biochemistry and Medical Genetics, University of Manitoba, Winnipeg, Manitoba R3E 0J9, Canada
| | - Tasnim H Beacon
- Department of Biochemistry and Medical Genetics, University of Manitoba, Winnipeg, Manitoba R3E 0J9, Canada; CancerCare Manitoba Research Institute, CancerCare Manitoba, Winnipeg, Manitoba R3E 0V9, Canada
| | - Ifeoluwa Adewumi
- Department of Biochemistry and Medical Genetics, University of Manitoba, Winnipeg, Manitoba R3E 0J9, Canada
| | - Camila López
- Department of Biochemistry and Medical Genetics, University of Manitoba, Winnipeg, Manitoba R3E 0J9, Canada
| | - Pingzhao Hu
- Department of Biochemistry and Medical Genetics, University of Manitoba, Winnipeg, Manitoba R3E 0J9, Canada; CancerCare Manitoba Research Institute, CancerCare Manitoba, Winnipeg, Manitoba R3E 0V9, Canada
| | - Wayne Xu
- Department of Biochemistry and Medical Genetics, University of Manitoba, Winnipeg, Manitoba R3E 0J9, Canada; CancerCare Manitoba Research Institute, CancerCare Manitoba, Winnipeg, Manitoba R3E 0V9, Canada
| | - James R Davie
- Department of Biochemistry and Medical Genetics, University of Manitoba, Winnipeg, Manitoba R3E 0J9, Canada; CancerCare Manitoba Research Institute, CancerCare Manitoba, Winnipeg, Manitoba R3E 0V9, Canada.
| |
Collapse
|
14
|
Dieci G. Removing quote marks from the RNA polymerase II CTD 'code'. Biosystems 2021; 207:104468. [PMID: 34216714 DOI: 10.1016/j.biosystems.2021.104468] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Revised: 06/24/2021] [Accepted: 06/27/2021] [Indexed: 11/27/2022]
Abstract
In eukaryotes, RNA polymerase II (Pol II) is responsible for the synthesis of all mRNAs and myriads of short and long untranslated RNAs, whose fabrication involves close spatiotemporal coordination between transcription, RNA processing and chromatin modification. Crucial for such a coordination is an unusual C-terminal domain (CTD) of the Pol II largest subunit, made of tandem repetitions (26 in yeast, 52 in chordates) of the heptapeptide with the consensus sequence YSPTSPS. Although largely unstructured and with poor sequence content, the Pol II CTD derives its extraordinary functional versatility from the fact that each amino acid in the heptapeptide can be posttranslationally modified, and that different combinations of CTD covalent marks are specifically recognized by different protein binding partners. These features have led to propose the existence of a Pol II CTD code, but this expression is generally used by authors with some caution, revealed by the frequent use of quote marks for the word 'code'. Based on the theoretical framework of code biology, it is argued here that the Pol II CTD modification system meets the requirements of a true organic code, where different CTD modification states represent organic signs whose organic meanings are biological reactions contributing to the many facets of RNA biogenesis in coordination with RNA synthesis by Pol II. Importantly, the Pol II CTD code is instantiated by adaptor proteins possessing at least two distinct domains, one of which devoted to specific recognition of CTD modification profiles. Furthermore, code rules can be altered by experimental interchange of CTD recognition domains of different adaptor proteins, a fact arguing in favor of the arbitrariness, and thus bona fide character, of the Pol II CTD code. Since the growing family of CTD adaptors includes RNA binding proteins and histone modification complexes, the Pol II CTD code is by its nature integrated with other organic codes, in particular the splicing code and the histone code. These issues will be discussed taking into account fascinating developments in Pol II CTD research, like the discovery of novel modifications at non-consensus sites, the recently recognized CTD physicochemical properties favoring liquid-liquid phase separation, and the discovery that the Pol II CTD, originated before the divergence of most extant eukaryotic taxa, has expanded and diversified with developmental complexity in animals and plants.
Collapse
Affiliation(s)
- Giorgio Dieci
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parco Area delle Scienze 23/A, 43124, Parma, Italy.
| |
Collapse
|