1
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Xu J, Sun X, Chen Z, Ma H, Liu Y. Super-resolution imaging of T lymphocyte activation reveals chromatin decondensation and disrupted nuclear envelope. Commun Biol 2024; 7:717. [PMID: 38858440 PMCID: PMC11164909 DOI: 10.1038/s42003-024-06393-1] [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: 10/12/2023] [Accepted: 05/23/2024] [Indexed: 06/12/2024] Open
Abstract
T lymphocyte activation plays a pivotal role in adaptive immune response and alters the spatial organization of nuclear architecture that subsequently impacts transcription activities. Here, using stochastic optical reconstruction microscopy (STORM), we observe dramatic de-condensation of chromatin and the disruption of nuclear envelope at a nanoscale resolution upon T lymphocyte activation. Super-resolution imaging reveals that such alterations in nuclear architecture are accompanied by the release of nuclear DNA into the cytoplasm, correlating with the degree of chromatin decompaction within the nucleus. The authors show that under the influence of metabolism, T lymphocyte activation de-condenses chromatin, disrupts the nuclear envelope, and releases DNA into the cytoplasm. Taken together, this result provides a direct, molecular-scale insight into the alteration in nuclear architecture. It suggests the release of nuclear DNA into the cytoplasm as a general consequence of chromatin decompaction after lymphocyte activation.
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Affiliation(s)
- Jianquan Xu
- Biomedical Optical Imaging Laboratory, Departments of Medicine and Bioengineering, University of Pittsburgh, Pittsburgh, PA, 15213, USA
| | - Xuejiao Sun
- Biomedical Optical Imaging Laboratory, Departments of Medicine and Bioengineering, University of Pittsburgh, Pittsburgh, PA, 15213, USA
| | - Zhangguo Chen
- UPMC Hillman Cancer Center, Division of Hematology and Oncology, Department of Medicine, University of Pittsburgh, Pittsburgh, PA, 15213, USA
| | - Hongqiang Ma
- Biomedical Optical Imaging Laboratory, Departments of Medicine and Bioengineering, University of Pittsburgh, Pittsburgh, PA, 15213, USA
- Department of Bioengineering, Beckman Institute for Advanced Science and Technology, University of Illinois Urbana-Champaign, Urbana, IL, 61801, USA
| | - Yang Liu
- Biomedical Optical Imaging Laboratory, Departments of Medicine and Bioengineering, University of Pittsburgh, Pittsburgh, PA, 15213, USA.
- Department of Bioengineering, Department of Electrical and Computer Engineering, Beckman Institute for Advanced Science and Technology, Cancer Center at Illinois, University of Illinois Urbana-Champaign, Urbana, IL, 61801, USA.
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2
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Benham CJ. DNA superhelicity. Nucleic Acids Res 2024; 52:22-48. [PMID: 37994702 PMCID: PMC10783518 DOI: 10.1093/nar/gkad1092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2023] [Revised: 10/20/2023] [Accepted: 11/06/2023] [Indexed: 11/24/2023] Open
Abstract
Closing each strand of a DNA duplex upon itself fixes its linking number L. This topological condition couples together the secondary and tertiary structures of the resulting ccDNA topoisomer, a constraint that is not present in otherwise identical nicked or linear DNAs. Fixing L has a range of structural, energetic and functional consequences. Here we consider how L having different integer values (that is, different superhelicities) affects ccDNA molecules. The approaches used are primarily theoretical, and are developed from a historical perspective. In brief, processes that either relax or increase superhelicity, or repartition what is there, may either release or require free energy. The energies involved can be substantial, sufficient to influence many events, directly or indirectly. Here two examples are developed. The changes of unconstrained superhelicity that occur during nucleosome attachment and release are examined. And a simple theoretical model of superhelically driven DNA structural transitions is described that calculates equilibrium distributions for populations of identical topoisomers. This model is used to examine how these distributions change with superhelicity and other factors, and applied to analyze several situations of biological interest.
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Affiliation(s)
- Craig J Benham
- UC Davis Genome Center, University of California, One Shields Avenue, Davis, CA 95616, USA
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3
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Sala L, Kumar M, Prajapat M, Chandrasekhar S, Cosby RL, La Rocca G, Macfarlan TS, Awasthi P, Chari R, Kruhlak M, Vidigal JA. AGO2 silences mobile transposons in the nucleus of quiescent cells. Nat Struct Mol Biol 2023; 30:1985-1995. [PMID: 37985687 DOI: 10.1038/s41594-023-01151-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Accepted: 09/27/2023] [Indexed: 11/22/2023]
Abstract
Argonaute 2 (AGO2) is a cytoplasmic component of the miRNA pathway, with essential roles in development and disease. Yet little is known about its regulation in vivo. Here we show that in quiescent mouse splenocytes, AGO2 localizes almost exclusively to the nucleus. AGO2 subcellular localization is modulated by the Pi3K-AKT-mTOR pathway, a well-established regulator of quiescence. Signaling through this pathway in proliferating cells promotes AGO2 cytoplasmic accumulation, at least in part by stimulating the expression of TNRC6, an essential AGO2 binding partner in the miRNA pathway. In quiescent cells in which mTOR signaling is low, AGO2 accumulates in the nucleus, where it binds to young mobile transposons co-transcriptionally to repress their expression via its catalytic domain. Our data point to an essential but previously unrecognized nuclear role for AGO2 during quiescence as part of a genome-defense system against young mobile elements and provide evidence of RNA interference in the soma of mammals.
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Affiliation(s)
- Laura Sala
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, The National Institutes of Health, Bethesda, MD, USA
| | - Manish Kumar
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, The National Institutes of Health, Bethesda, MD, USA
| | - Mahendra Prajapat
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, The National Institutes of Health, Bethesda, MD, USA
| | - Srividya Chandrasekhar
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, The National Institutes of Health, Bethesda, MD, USA
| | - Rachel L Cosby
- The Eunice Kennedy Shriver National Institute of Child Health and Human Development, The National Institutes of Health, Bethesda, MD, USA
- The National Institute for General Medical Sciences, The National Institutes of Health, Bethesda, MD, USA
| | - Gaspare La Rocca
- Cancer Biology and Genetics Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Todd S Macfarlan
- The Eunice Kennedy Shriver National Institute of Child Health and Human Development, The National Institutes of Health, Bethesda, MD, USA
| | - Parirokh Awasthi
- Laboratory Animal Sciences Program, Frederick National Lab for Cancer Research, The National Institutes of Health, Frederick, MD, USA
| | - Raj Chari
- Laboratory Animal Sciences Program, Frederick National Lab for Cancer Research, The National Institutes of Health, Frederick, MD, USA
| | - Michael Kruhlak
- CCR Confocal Microscopy Core Facility, National Cancer Institute, The National Institutes of Health, Bethesda, MD, USA
| | - Joana A Vidigal
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, The National Institutes of Health, Bethesda, MD, USA.
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4
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Malik S, Roeder RG. Regulation of the RNA polymerase II pre-initiation complex by its associated coactivators. Nat Rev Genet 2023; 24:767-782. [PMID: 37532915 PMCID: PMC11088444 DOI: 10.1038/s41576-023-00630-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/15/2023] [Indexed: 08/04/2023]
Abstract
The RNA polymerase II (Pol II) pre-initiation complex (PIC) is a critical node in eukaryotic transcription regulation, and its formation is the major rate-limiting step in transcriptional activation. Diverse cellular signals borne by transcriptional activators converge on this large, multiprotein assembly and are transduced via intermediary factors termed coactivators. Cryogenic electron microscopy, multi-omics and single-molecule approaches have recently offered unprecedented insights into both the structure and cellular functions of the PIC and two key PIC-associated coactivators, Mediator and TFIID. Here, we review advances in our understanding of how Mediator and TFIID interact with activators and affect PIC formation and function. We also discuss how their functions are influenced by their chromatin environment and selected cofactors. We consider how, through its multifarious interactions and functionalities, a Mediator-containing and TFIID-containing PIC can yield an integrated signal processing system with the flexibility to determine the unique temporal and spatial expression pattern of a given gene.
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Affiliation(s)
- Sohail Malik
- Laboratory of Biochemistry & Molecular Biology, The Rockefeller University, New York, NY, USA.
| | - Robert G Roeder
- Laboratory of Biochemistry & Molecular Biology, The Rockefeller University, New York, NY, USA
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5
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Salerno F, Howden AJM, Matheson LS, Gizlenci Ö, Screen M, Lingel H, Brunner-Weinzierl MC, Turner M. An integrated proteome and transcriptome of B cell maturation defines poised activation states of transitional and mature B cells. Nat Commun 2023; 14:5116. [PMID: 37612319 PMCID: PMC10447577 DOI: 10.1038/s41467-023-40621-2] [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: 02/09/2023] [Accepted: 08/03/2023] [Indexed: 08/25/2023] Open
Abstract
During B cell maturation, transitional and mature B cells acquire cell-intrinsic features that determine their ability to exit quiescence and mount effective immune responses. Here we use label-free proteomics to quantify the proteome of B cell subsets from the mouse spleen and map the differential expression of environmental sensing, transcription, and translation initiation factors that define cellular identity and function. Cross-examination of the full-length transcriptome and proteome identifies mRNAs related to B cell activation and antibody secretion that are not accompanied by detection of the encoded proteins. In addition, proteomic data further suggests that the translational repressor PDCD4 restrains B cell responses, in particular those from marginal zone B cells, to a T-cell independent antigen. In summary, our molecular characterization of B cell maturation presents a valuable resource to further explore the mechanisms underpinning the specialized functions of B cell subsets, and suggest the presence of 'poised' mRNAs that enable expedited B cell responses.
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Affiliation(s)
- Fiamma Salerno
- Immunology programme, The Babraham Institute, Cambridge, UK.
| | | | | | - Özge Gizlenci
- Immunology programme, The Babraham Institute, Cambridge, UK
| | - Michael Screen
- Immunology programme, The Babraham Institute, Cambridge, UK
| | - Holger Lingel
- Department of Experimental Pediatrics, Otto-von-Guericke-University, Magdeburg, Germany
| | | | - Martin Turner
- Immunology programme, The Babraham Institute, Cambridge, UK.
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6
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Xu D, Huang Y, Luo L, Tang L, Lu M, Cao H, Wang F, Diao Y, Lyubchenko L, Kapranov P. Genome-Wide Profiling of Endogenous Single-Stranded DNA Using the SSiNGLe-P1 Method. Int J Mol Sci 2023; 24:12062. [PMID: 37569439 PMCID: PMC10418711 DOI: 10.3390/ijms241512062] [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: 06/30/2023] [Revised: 07/23/2023] [Accepted: 07/25/2023] [Indexed: 08/13/2023] Open
Abstract
Endogenous single-stranded DNA (essDNA) can form in a mammalian genome as the result of a variety of molecular processes and can both play important roles inside the cell as well as have detrimental consequences to genome integrity, much of which remains to be fully understood. Here, we established the SSiNGLe-P1 approach based on limited digestion by P1 endonuclease for high-throughput genome-wide identification of essDNA regions. We applied this method to profile essDNA in both human mitochondrial and nuclear genomes. In the mitochondrial genome, the profiles of essDNA provide new evidence to support the strand-displacement model of mitochondrial DNA replication. In the nuclear genome, essDNA regions were found to be enriched in certain types of functional genomic elements, particularly, the origins of DNA replication, R-loops, and to a lesser degree, in promoters. Furthermore, interestingly, many of the essDNA regions identified by SSiNGLe-P1 have not been annotated and thus could represent yet unknown functional elements.
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Affiliation(s)
- Dongyang Xu
- Institute of Genomics, School of Medicine, Huaqiao University, 668 Jimei Road, Xiamen 361021, China; (D.X.)
| | - Yu Huang
- Institute of Genomics, School of Medicine, Huaqiao University, 668 Jimei Road, Xiamen 361021, China; (D.X.)
| | - Lingcong Luo
- Institute of Genomics, School of Medicine, Huaqiao University, 668 Jimei Road, Xiamen 361021, China; (D.X.)
| | - Lu Tang
- Institute of Genomics, School of Medicine, Huaqiao University, 668 Jimei Road, Xiamen 361021, China; (D.X.)
| | - Meng Lu
- Institute of Genomics, School of Medicine, Huaqiao University, 668 Jimei Road, Xiamen 361021, China; (D.X.)
| | - Huifen Cao
- Institute of Genomics, School of Medicine, Huaqiao University, 668 Jimei Road, Xiamen 361021, China; (D.X.)
| | - Fang Wang
- Institute of Genomics, School of Medicine, Huaqiao University, 668 Jimei Road, Xiamen 361021, China; (D.X.)
| | - Yong Diao
- Institute of Genomics, School of Medicine, Huaqiao University, 668 Jimei Road, Xiamen 361021, China; (D.X.)
| | - Liudmila Lyubchenko
- National Medical Research Center for Radiology, Ministry of Health of Russia, 125284 Moscow, Russia
| | - Philipp Kapranov
- Institute of Genomics, School of Medicine, Huaqiao University, 668 Jimei Road, Xiamen 361021, China; (D.X.)
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen 361102, China
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7
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Herbert A, Pavlov F, Konovalov D, Poptsova M. Conserved microRNAs and Flipons Shape Gene Expression during Development by Altering Promoter Conformations. Int J Mol Sci 2023; 24:ijms24054884. [PMID: 36902315 PMCID: PMC10003719 DOI: 10.3390/ijms24054884] [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: 12/27/2022] [Revised: 02/09/2023] [Accepted: 02/14/2023] [Indexed: 03/06/2023] Open
Abstract
The classical view of gene regulation draws from prokaryotic models, where responses to environmental changes involve operons regulated by sequence-specific protein interactions with DNA, although it is now known that operons are also modulated by small RNAs. In eukaryotes, pathways based on microRNAs (miR) regulate the readout of genomic information from transcripts, while alternative nucleic acid structures encoded by flipons influence the readout of genetic programs from DNA. Here, we provide evidence that miR- and flipon-based mechanisms are deeply connected. We analyze the connection between flipon conformation and the 211 highly conserved human miR that are shared with other placental and other bilateral species. The direct interaction between conserved miR (c-miR) and flipons is supported by sequence alignments and the engagement of argonaute proteins by experimentally validated flipons as well as their enrichment in promoters of coding transcripts important in multicellular development, cell surface glycosylation and glutamatergic synapse specification with significant enrichments at false discovery rates as low as 10-116. We also identify a second subset of c-miR that targets flipons essential for retrotransposon replication, exploiting that vulnerability to limit their spread. We propose that miR can act in a combinatorial manner to regulate the readout of genetic information by specifying when and where flipons form non-B DNA (NoB) conformations, providing the interactions of the conserved hsa-miR-324-3p with RELA and the conserved hsa-miR-744 with ARHGAP5 genes as examples.
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Affiliation(s)
- Alan Herbert
- InsideOutBio, 42 8th Street, Charlestown, MA 02129, USA
- Correspondence:
| | - Fedor Pavlov
- Laboratory of Bioinformatics, Faculty of Computer Science, National Research University Higher School of Economics, 11 Pokrovsky Bulvar, 101000 Moscow, Russia
| | - Dmitrii Konovalov
- Laboratory of Bioinformatics, Faculty of Computer Science, National Research University Higher School of Economics, 11 Pokrovsky Bulvar, 101000 Moscow, Russia
| | - Maria Poptsova
- Laboratory of Bioinformatics, Faculty of Computer Science, National Research University Higher School of Economics, 11 Pokrovsky Bulvar, 101000 Moscow, Russia
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8
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A de novo transcription-dependent TAD boundary underpins critical multiway interactions during antibody class switch recombination. Mol Cell 2023; 83:681-697.e7. [PMID: 36736317 DOI: 10.1016/j.molcel.2023.01.014] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2022] [Revised: 11/04/2022] [Accepted: 01/09/2023] [Indexed: 02/05/2023]
Abstract
Interactions between transcription and cohesin-mediated loop extrusion can influence 3D chromatin architecture. However, their relevance in biology is unclear. Here, we report a direct role for such interactions in the mechanism of antibody class switch recombination (CSR) at the murine immunoglobulin heavy chain locus (Igh). Using Tri-C to measure higher-order multiway interactions on single alleles, we find that the juxtaposition (synapsis) of transcriptionally active donor and acceptor Igh switch (S) sequences, an essential step in CSR, occurs via the interaction of loop extrusion complexes with a de novo topologically associating domain (TAD) boundary formed via transcriptional activity across S regions. Surprisingly, synapsis occurs predominantly in proximity to the 3' CTCF-binding element (3'CBE) rather than the Igh super-enhancer, suggesting a two-step mechanism whereby transcription of S regions is not topologically coupled to synapsis, as has been previously proposed. Altogether, these insights advance our understanding of how 3D chromatin architecture regulates CSR.
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9
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He X, Zhao J, Adilijiang A, Hong P, Chen P, Lin X, Xie J, Du Y, Liu Y, Lin L, Jin HY, Hong Y, Liu WH, Xiao C. Dhx33 promotes B-cell growth and proliferation by controlling activation-induced rRNA upregulation. Cell Mol Immunol 2023; 20:277-291. [PMID: 36631557 PMCID: PMC9970960 DOI: 10.1038/s41423-022-00972-0] [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: 08/29/2022] [Accepted: 12/21/2022] [Indexed: 01/12/2023] Open
Abstract
Upon recognition of foreign antigens, naïve B cells undergo rapid activation, growth, and proliferation. How B-cell growth and proliferation are coupled with activation remains poorly understood. Combining CRISPR/Cas9-mediated functional analysis and mouse genetics approaches, we found that Dhx33, an activation-induced RNA helicase, plays a critical role in coupling B-cell activation with growth and proliferation. Mutant mice with B-cell-specific deletion of Dhx33 exhibited impaired B-cell development, germinal center reactions, plasma cell differentiation, and antibody production. Dhx33-deficient B cells appeared normal in the steady state and early stage of activation but were retarded in growth and proliferation. Mechanistically, Dhx33 played an indispensable role in activation-induced upregulation of ribosomal DNA (rDNA) transcription. In the absence of Dhx33, activated B cells were compromised in their ability to ramp up 47S ribosomal RNA (rRNA) production and ribosome biogenesis, resulting in nucleolar stress, p53 accumulation, and cellular death. Our findings demonstrate an essential role for Dhx33 in coupling B-cell activation with growth and proliferation and suggest that Dhx33 inhibition is a potential therapy for lymphoma and antibody-mediated autoimmune diseases.
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Affiliation(s)
- Xiaoyu He
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Faculty of Medicine and Life Sciences, Xiamen University, Xiamen, Fujian, China
| | - Jiayi Zhao
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Faculty of Medicine and Life Sciences, Xiamen University, Xiamen, Fujian, China
| | - Abidan Adilijiang
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Faculty of Medicine and Life Sciences, Xiamen University, Xiamen, Fujian, China
| | - Peicheng Hong
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Faculty of Medicine and Life Sciences, Xiamen University, Xiamen, Fujian, China
| | - Pengda Chen
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Faculty of Medicine and Life Sciences, Xiamen University, Xiamen, Fujian, China
| | - Xinyong Lin
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Faculty of Medicine and Life Sciences, Xiamen University, Xiamen, Fujian, China
| | - Jun Xie
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Faculty of Medicine and Life Sciences, Xiamen University, Xiamen, Fujian, China
| | - Ying Du
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Faculty of Medicine and Life Sciences, Xiamen University, Xiamen, Fujian, China
| | - Yun Liu
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Faculty of Medicine and Life Sciences, Xiamen University, Xiamen, Fujian, China
| | - Lianghua Lin
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Faculty of Medicine and Life Sciences, Xiamen University, Xiamen, Fujian, China
| | - Hyun Yong Jin
- Department of Immunology and Microbiology, The Scripps Research Institute, La Jolla, CA, 92037, USA
- Genentech Inc., South San Francisco, CA, 94080, USA
| | - Yazhen Hong
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Faculty of Medicine and Life Sciences, Xiamen University, Xiamen, Fujian, China
| | - Wen-Hsien Liu
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Faculty of Medicine and Life Sciences, Xiamen University, Xiamen, Fujian, China.
| | - Changchun Xiao
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Faculty of Medicine and Life Sciences, Xiamen University, Xiamen, Fujian, China.
- Department of Immunology and Microbiology, The Scripps Research Institute, La Jolla, CA, 92037, USA.
- Sanofi Institute for Biomedical Research, Suzhou, Jiangsu, 215123, China.
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10
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O’Grady TM, Baddoo M, Flemington SA, Ishaq EY, Ungerleider NA, Flemington EK. Reversal of splicing infidelity is a pre-activation step in B cell differentiation. Front Immunol 2022; 13:1060114. [PMID: 36601126 PMCID: PMC9806119 DOI: 10.3389/fimmu.2022.1060114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2022] [Accepted: 11/28/2022] [Indexed: 12/23/2022] Open
Abstract
Introduction B cell activation and differentiation is central to the adaptive immune response. Changes in exon usage can have major impacts on cellular signaling and differentiation but have not been systematically explored in differentiating B cells. Methods We analyzed exon usage and intron retention in RNA-Seq data from subsets of human B cells at various stages of differentiation, and in an in vitro laboratory model of B cell activation and differentiation (Epstein Barr virus infection). Results Blood naïve B cells were found to have an unusual splicing profile, with unannotated splicing events in over 30% of expressed genes. Splicing changed substantially upon naïve B cell entry into secondary lymphoid tissue and before activation, involving significant increases in exon commitment and reductions in intron retention. These changes preferentially involved short introns with weak splice sites and were likely mediated by an overall increase in splicing efficiency induced by the lymphoid environment. The majority of transcripts affected by splicing changes showed restoration of encoded conserved protein domains and/or reduced targeting to the nonsense-mediated decay pathway. Affected genes were enriched in functionally important immune cell activation pathways such as antigen-mediated signaling, cell cycle control and mRNA processing and splicing. Discussion Functional observations from donor B cell subsets in progressive states of differentiation and from timecourse experiments using the in vitro model suggest that these widespread changes in mRNA splicing play a role in preparing naïve B cells for the decisive step of antigen-mediated activation and differentiation.
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Affiliation(s)
- Tina M. O’Grady
- Department of Pathology & Laboratory Medicine, Tulane University School of Medicine, New Orleans, LA, United States
| | - Melody Baddoo
- Department of Pathology & Laboratory Medicine, Tulane University School of Medicine, New Orleans, LA, United States
| | - Samuel A. Flemington
- Tulane Cancer Center, Tulane University School of Medicine, New Orleans, LA, United States
| | - Eman Y. Ishaq
- Department of Pathology & Laboratory Medicine, Tulane University School of Medicine, New Orleans, LA, United States
| | - Nathan A. Ungerleider
- Department of Pathology & Laboratory Medicine, Tulane University School of Medicine, New Orleans, LA, United States
| | - Erik K. Flemington
- Department of Pathology & Laboratory Medicine, Tulane University School of Medicine, New Orleans, LA, United States
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11
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Salloum D, Singh K, Davidson NR, Cao L, Kuo D, Sanghvi VR, Jiang M, Lafoz MT, Viale A, Ratsch G, Wendel HG. A Rapid Translational Immune Response Program in CD8 Memory T Lymphocytes. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2022; 209:1189-1199. [PMID: 36002234 PMCID: PMC9492650 DOI: 10.4049/jimmunol.2100537] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Accepted: 05/25/2022] [Indexed: 01/04/2023]
Abstract
The activation of memory T cells is a very rapid and concerted cellular response that requires coordination between cellular processes in different compartments and on different time scales. In this study, we use ribosome profiling and deep RNA sequencing to define the acute mRNA translation changes in CD8 memory T cells following initial activation events. We find that initial translation enables subsequent events of human and mouse T cell activation and expansion. Briefly, early events in the activation of Ag-experienced CD8 T cells are insensitive to transcriptional blockade with actinomycin D, and instead depend on the translation of pre-existing mRNAs and are blocked by cycloheximide. Ribosome profiling identifies ∼92 mRNAs that are recruited into ribosomes following CD8 T cell stimulation. These mRNAs typically have structured GC and pyrimidine-rich 5' untranslated regions and they encode key regulators of T cell activation and proliferation such as Notch1, Ifngr1, Il2rb, and serine metabolism enzymes Psat1 and Shmt2 (serine hydroxymethyltransferase 2), as well as translation factors eEF1a1 (eukaryotic elongation factor α1) and eEF2 (eukaryotic elongation factor 2). The increased production of receptors of IL-2 and IFN-γ precedes the activation of gene expression and augments cellular signals and T cell activation. Taken together, we identify an early RNA translation program that acts in a feed-forward manner to enable the rapid and dramatic process of CD8 memory T cell expansion and activation.
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Affiliation(s)
- Darin Salloum
- Cancer Biology and Genetics Program, Memorial Sloan Kettering Cancer Center, New York, NY
| | - Kamini Singh
- Cancer Biology and Genetics Program, Memorial Sloan Kettering Cancer Center, New York, NY.,Department of Molecular Pharmacology, Albert Einstein College of Medicine, Albert Einstein Cancer Center, Bronx, NY
| | - Natalie R Davidson
- Department of Computer Science, ETH Zurich, Zurich, Switzerland.,Department of Biology, ETH Zurich, Zurich, Switzerland.,Swiss Institute for Bioinformatics, Lausanne, Switzerland
| | - Linlin Cao
- Swiss Institute for Experimental Cancer Research, EPFL, Lausanne, Switzerland
| | - David Kuo
- Department of Physiology, Biophysics, and Systems Biology, Weill Cornell Graduate School of Medical Sciences, New York, NY
| | - Viraj R Sanghvi
- Cancer Biology and Genetics Program, Memorial Sloan Kettering Cancer Center, New York, NY.,Department of Molecular and Cellular Pharmacology, Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami FL
| | - Man Jiang
- Cancer Biology and Genetics Program, Memorial Sloan Kettering Cancer Center, New York, NY
| | - Maria Tello Lafoz
- Immunology Program, Memorial Sloan Kettering Cancer Center, New York, NY; and
| | - Agnes Viale
- Integrated Genomics Operation, Marie-Josée and Henry R. Kravis Center for Molecular Oncology, Memorial Sloan Kettering Cancer Center, New York, NY
| | - Gunnar Ratsch
- Department of Computer Science, ETH Zurich, Zurich, Switzerland.,Department of Biology, ETH Zurich, Zurich, Switzerland.,Swiss Institute for Bioinformatics, Lausanne, Switzerland
| | - Hans-Guido Wendel
- Cancer Biology and Genetics Program, Memorial Sloan Kettering Cancer Center, New York, NY;
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12
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Zhao Y, Vartak SV, Conte A, Wang X, Garcia DA, Stevens E, Kyoung Jung S, Kieffer-Kwon KR, Vian L, Stodola T, Moris F, Chopp L, Preite S, Schwartzberg PL, Kulinski JM, Olivera A, Harly C, Bhandoola A, Heuston EF, Bodine DM, Urrutia R, Upadhyaya A, Weirauch MT, Hager G, Casellas R. "Stripe" transcription factors provide accessibility to co-binding partners in mammalian genomes. Mol Cell 2022; 82:3398-3411.e11. [PMID: 35863348 PMCID: PMC9481673 DOI: 10.1016/j.molcel.2022.06.029] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Revised: 04/06/2022] [Accepted: 06/22/2022] [Indexed: 10/17/2022]
Abstract
Regulatory elements activate promoters by recruiting transcription factors (TFs) to specific motifs. Notably, TF-DNA interactions often depend on cooperativity with colocalized partners, suggesting an underlying cis-regulatory syntax. To explore TF cooperativity in mammals, we analyze ∼500 mouse and human primary cells by combining an atlas of TF motifs, footprints, ChIP-seq, transcriptomes, and accessibility. We uncover two TF groups that colocalize with most expressed factors, forming stripes in hierarchical clustering maps. The first group includes lineage-determining factors that occupy DNA elements broadly, consistent with their key role in tissue-specific transcription. The second one, dubbed universal stripe factors (USFs), comprises ∼30 SP, KLF, EGR, and ZBTB family members that recognize overlapping GC-rich sequences in all tissues analyzed. Knockouts and single-molecule tracking reveal that USFs impart accessibility to colocalized partners and increase their residence time. Mammalian cells have thus evolved a TF superfamily with overlapping DNA binding that facilitate chromatin accessibility.
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Affiliation(s)
- Yongbing Zhao
- The NIH Regulome Project, National Institutes of Health, Bethesda, MD 20892, USA; Lymphocyte Nuclear Biology, NIAMS-NCI, NIH, Bethesda, MD 20892, USA.
| | - Supriya V Vartak
- The NIH Regulome Project, National Institutes of Health, Bethesda, MD 20892, USA; Lymphocyte Nuclear Biology, NIAMS-NCI, NIH, Bethesda, MD 20892, USA
| | - Andrea Conte
- The NIH Regulome Project, National Institutes of Health, Bethesda, MD 20892, USA; Lymphocyte Nuclear Biology, NIAMS-NCI, NIH, Bethesda, MD 20892, USA
| | - Xiang Wang
- The NIH Regulome Project, National Institutes of Health, Bethesda, MD 20892, USA; Lymphocyte Nuclear Biology, NIAMS-NCI, NIH, Bethesda, MD 20892, USA
| | - David A Garcia
- Laboratory of Receptor Biology and Gene Expression, NCI, NIH, Bethesda, MD 20893, USA; Department of Physics, University of Maryland, College Park, MD 20742, USA
| | - Evan Stevens
- Lymphocyte Nuclear Biology, NIAMS-NCI, NIH, Bethesda, MD 20892, USA
| | - Seol Kyoung Jung
- The NIH Regulome Project, National Institutes of Health, Bethesda, MD 20892, USA; Lymphocyte Nuclear Biology, NIAMS-NCI, NIH, Bethesda, MD 20892, USA
| | | | - Laura Vian
- Lymphocyte Nuclear Biology, NIAMS-NCI, NIH, Bethesda, MD 20892, USA
| | - Timothy Stodola
- Genomic Sciences and Precision Medicine Center (GSPMC), Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Francisco Moris
- EntreChem S.L., Vivero Ciencias de la Salud, 33011 Oviedo, Spain
| | - Laura Chopp
- Laboratory of Immune Cell Biology, NCI, NIH, Bethesda, MD 20892, USA
| | - Silvia Preite
- Laboratory of Immune System Biology, NIAID, NIH, Bethesda, MD 20892, USA
| | | | - Joseph M Kulinski
- Mast cell Biology Section, Laboratory of Allergic Diseases, NIAID, NIH, Bethesda, MD 20892, USA
| | - Ana Olivera
- Mast cell Biology Section, Laboratory of Allergic Diseases, NIAID, NIH, Bethesda, MD 20892, USA
| | - Christelle Harly
- Laboratory of Genome Integrity, NCI, NIH, Bethesda, MD 20892, USA
| | | | | | - David M Bodine
- Genetics and Molecular Biology Branch, NHGRI, NIH, Bethesda, MD 20892, USA
| | - Raul Urrutia
- Genomic Sciences and Precision Medicine Center (GSPMC), Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Arpita Upadhyaya
- Department of Physics, University of Maryland, College Park, MD 20742, USA
| | - Matthew T Weirauch
- Divisions of Biomedical Informatics and Developmental Biology, Center for Autoimmune Genomics and Etiology (CAGE), Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA; Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45229, USA
| | - Gordon Hager
- Laboratory of Receptor Biology and Gene Expression, NCI, NIH, Bethesda, MD 20893, USA
| | - Rafael Casellas
- The NIH Regulome Project, National Institutes of Health, Bethesda, MD 20892, USA; Lymphocyte Nuclear Biology, NIAMS-NCI, NIH, Bethesda, MD 20892, USA.
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13
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How to Shut Down Transcription in Archaea during Virus Infection. Microorganisms 2022; 10:microorganisms10091824. [PMID: 36144426 PMCID: PMC9501531 DOI: 10.3390/microorganisms10091824] [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: 08/10/2022] [Revised: 09/09/2022] [Accepted: 09/10/2022] [Indexed: 11/16/2022] Open
Abstract
Multisubunit RNA polymerases (RNAPs) carry out transcription in all domains of life; during virus infection, RNAPs are targeted by transcription factors encoded by either the cell or the virus, resulting in the global repression of transcription with distinct outcomes for different host–virus combinations. These repressors serve as versatile molecular probes to study RNAP mechanisms, as well as aid the exploration of druggable sites for the development of new antibiotics. Here, we review the mechanisms and structural basis of RNAP inhibition by the viral repressor RIP and the crenarchaeal negative regulator TFS4, which follow distinct strategies. RIP operates by occluding the DNA-binding channel and mimicking the initiation factor TFB/TFIIB. RIP binds tightly to the clamp and locks it into one fixed position, thereby preventing conformational oscillations that are critical for RNAP function as it progresses through the transcription cycle. TFS4 engages with RNAP in a similar manner to transcript cleavage factors such as TFS/TFIIS through the NTP-entry channel; TFS4 interferes with the trigger loop and bridge helix within the active site by occlusion and allosteric mechanisms, respectively. The conformational changes in RNAP described above are universally conserved and are also seen in inactive dimers of eukaryotic RNAPI and several inhibited RNAP complexes of both bacterial and eukaryotic RNA polymerases, including inactive states that precede transcription termination. A comparison of target sites and inhibitory mechanisms reveals that proteinaceous repressors and RNAP-specific antibiotics use surprisingly common ways to inhibit RNAP function.
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14
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Abstract
TOP1 CAD-seq enables mapping of TOP1 sites of covalent engagement with DNA. The procedure depends upon enrichment of DNA-covalent adducts using chaotropic salts and immunoprecipitation with an antibody specific for TOP1. Here, we describe a step-by-step protocol compatible with Illumina sequencing and bioinformatic pipeline for preliminary data analysis. Compared to other approaches for the genomic study of topoisomerases, TOP1 CAD-seq provides information about active TOP1 engaged on the DNA, taking advantage of low background due to absence of crosslinking. For complete details on the use and execution of this protocol, please refer to Das et al. (2022). TOP1 CAD-seq maps sites of topoisomerase 1 catalytic engagement with the DNA The absence of a cross-linking step reduces the background signal The method is high throughput and takes no longer than a regular ChIP-seq protocol The method can be used as a proxy to assess the level of supercoiling in the genome
Publisher’s note: Undertaking any experimental protocol requires adherence to local institutional guidelines for laboratory safety and ethics.
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15
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Gala HP, Saha D, Venugopal N, Aloysius A, Purohit G, Dhawan J. A transcriptionally repressed quiescence program is associated with paused RNAPII and is poised for cell cycle reentry. J Cell Sci 2022; 135:275901. [PMID: 35781573 DOI: 10.1242/jcs.259789] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Accepted: 06/27/2022] [Indexed: 11/20/2022] Open
Abstract
Adult stem cells persist in mammalian tissues by entering a state of reversible quiescence/ G0, associated with low transcription. Using cultured myoblasts and muscle stem cells, we report that in G0, global RNA content and synthesis are substantially repressed, correlating with decreased RNA Polymerase II (RNAPII) expression and activation. Integrating RNAPII occupancy and transcriptome profiling, we identify repressed networks and a role for promoter-proximal RNAPII pausing in G0. Strikingly, RNAPII shows enhanced pausing in G0 on repressed genes encoding regulators of RNA biogenesis (Nucleolin, Rps24, Ctdp1); release of pausing is associated with their increased expression in G1. Knockdown of these transcripts in proliferating cells leads to induction of G0 markers, confirming the importance of their repression in establishment of G0. A targeted screen of RNAPII regulators revealed that knockdown of Aff4 (positive regulator of elongation) unexpectedly enhances expression of G0-stalled genes and hastens S phase; NELF, a regulator of pausing appears to be dispensable. We propose that RNAPII pausing contributes to transcriptional control of a subset of G0-repressed genes to maintain quiescence and impacts the timing of the G0-G1 transition.
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Affiliation(s)
- Hardik P Gala
- Centre for Cellular and Molecular Biology, Hyderabad, 500007, India.,Institute for Stem Cell Science and Regenerative Medicine, Bangalore, 560065, India
| | - Debarya Saha
- Centre for Cellular and Molecular Biology, Hyderabad, 500007, India
| | - Nisha Venugopal
- Centre for Cellular and Molecular Biology, Hyderabad, 500007, India.,Institute for Stem Cell Science and Regenerative Medicine, Bangalore, 560065, India
| | - Ajoy Aloysius
- Centre for Cellular and Molecular Biology, Hyderabad, 500007, India.,Institute for Stem Cell Science and Regenerative Medicine, Bangalore, 560065, India.,National Center for Biological Sciences, Bangalore, 560065, India
| | - Gunjan Purohit
- Centre for Cellular and Molecular Biology, Hyderabad, 500007, India
| | - Jyotsna Dhawan
- Centre for Cellular and Molecular Biology, Hyderabad, 500007, India.,Institute for Stem Cell Science and Regenerative Medicine, Bangalore, 560065, India
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16
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Martella C, Waast L, Pique C. [Tax, the puppet master of HTLV-1 transcription]. Med Sci (Paris) 2022; 38:359-365. [PMID: 35485896 DOI: 10.1051/medsci/2022039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Retroviruses exploit the RNA polymerase II transcription machinery for the transcription of their genes. This is the case of Human T-lymphotropic virus type 1 (HTLV-1), the retrovirus responsible for adult T-cell leukemia and for various inflammatory diseases. HTLV-1 transcription is under the control of the viral protein Tax, which exhibits an original mode of action since it does not rely on direct promoter interaction but rather on the recruitment of various cellular factors and cofactors of transcription. The factors that Tax recruits are involved in the initial step of promoter activation but also in the subsequent steps of the transcription process itself. This review describes this particular mechanism of viral transcription, from the epigenetic release of the viral promoter to the elongation of the neosynthesized viral silencing transcripts.
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Affiliation(s)
- Christophe Martella
- Équipe Rétrovirus, infection et latence, Université Paris Cité, Inserm U1016, CNRS UMR8104, Institut Cochin, 22 rue Méchain, 75014 Paris, France
| | - Laetitia Waast
- Équipe Rétrovirus, infection et latence, Université Paris Cité, Inserm U1016, CNRS UMR8104, Institut Cochin, 22 rue Méchain, 75014 Paris, France
| | - Claudine Pique
- Équipe Rétrovirus, infection et latence, Université Paris Cité, Inserm U1016, CNRS UMR8104, Institut Cochin, 22 rue Méchain, 75014 Paris, France
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17
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Abstract
Centromeres, the chromosomal loci where spindle fibers attach during cell division to segregate chromosomes, are typically found within satellite arrays in plants and animals. Satellite arrays have been difficult to analyze because they comprise megabases of tandem head-to-tail highly repeated DNA sequences. Much evidence suggests that centromeres are epigenetically defined by the location of nucleosomes containing the centromere-specific histone H3 variant cenH3, independently of the DNA sequences where they are located; however, the reason that cenH3 nucleosomes are generally found on rapidly evolving satellite arrays has remained unclear. Recently, long-read sequencing technology has clarified the structures of satellite arrays and sparked rethinking of how they evolve, and new experiments and analyses have helped bring both understanding and further speculation about the role these highly repeated sequences play in centromere identification.
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Affiliation(s)
- Paul B Talbert
- Howard Hughes Medical Institute, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA
| | - Steven Henikoff
- Howard Hughes Medical Institute, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA
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18
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Abstract
Gene transcription does not only require writers of active histone modifications; on-site opposition by erasers is essential for many genes. Here, we propose the concept of dynamic opposition of histone modifications to explain this conundrum. We highlight the requirement of HDACs for acetylation balance at superenhancers, and the requirement of KDM5A for H4K3me3 recycling at highly active gene promoters. We propose that histone post-translational modifications regulate charge balance for biomolecular condensate formation and nucleosome turnover and form a short-term memory that informs lock-and-step checkpoints for chromatin engagement by RNA polymerase II.
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Affiliation(s)
- Ana María Garzón-Porras
- Department of Genetics and Genome Sciences, Case Western Reserve University, Cleveland, Ohio 44106, United States
| | - Emma Chory
- Media Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts 02142, United States
| | - Berkley E. Gryder
- Department of Genetics and Genome Sciences, Case Western Reserve University, Cleveland, Ohio 44106, United States
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19
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Abstract
The compaction of linear DNA into micrometer-sized nuclear boundaries involves the establishment of specific three-dimensional (3D) DNA structures complexed with histone proteins that form chromatin. The resulting structures modulate essential nuclear processes such as transcription, replication, and repair to facilitate or impede their multi-step progression and these contribute to dynamic modification of the 3D-genome organization. It is generally accepted that protein–protein and protein–DNA interactions form the basis of 3D-genome organization. However, the constant generation of mechanical forces, torques, and other stresses produced by various proteins translocating along DNA could be playing a larger role in genome organization than currently appreciated. Clearly, a thorough understanding of the mechanical determinants imposed by DNA transactions on the 3D organization of the genome is required. We provide here an overview of our current knowledge and highlight the importance of DNA and chromatin mechanics in gene expression.
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Affiliation(s)
- Rajiv Kumar Jha
- Gene Regulation Section, Laboratory of Pathology, Nci/nih, Bethesda, MD USA
| | - David Levens
- Gene Regulation Section, Laboratory of Pathology, Nci/nih, Bethesda, MD USA
| | - Fedor Kouzine
- Gene Regulation Section, Laboratory of Pathology, Nci/nih, Bethesda, MD USA
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20
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KAS-seq: genome-wide sequencing of single-stranded DNA by N 3-kethoxal-assisted labeling. Nat Protoc 2022; 17:402-420. [PMID: 35013616 PMCID: PMC8923001 DOI: 10.1038/s41596-021-00647-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Accepted: 09/22/2021] [Indexed: 02/03/2023]
Abstract
Transcription and its dynamics are crucial for gene expression regulation. However, very few methods can directly read out transcriptional activity with low-input material and high temporal resolution. This protocol describes KAS-seq, a robust and sensitive approach for capturing genome-wide single-stranded DNA (ssDNA) profiles using N3-kethoxal-assisted labeling. We developed N3-kethoxal, an azido derivative of kethoxal that reacts with deoxyguanosine bases of ssDNA in live cells within 5-10 min at 37 °C, allowing the capture of dynamic changes. Downstream biotinylation of labeled DNA occurs via copper-free click chemistry. Altogether, the KAS-seq procedure involves N3-kethoxal labeling, DNA isolation, biotinylation, fragmentation, affinity pull-down, library preparation, sequencing and bioinformatics analysis. The pre-library construction labeling and enrichment can be completed in as little as 3-4 h and is applicable to both animal tissue and as few as 1,000 cultured cells. Our recent study shows that ssDNA signals measured by KAS-seq simultaneously reveal the dynamics of transcriptionally engaged RNA polymerase (Pol) II, transcribing enhancers, RNA Pol I and Pol III activities and potentially non-canonical DNA structures with high analytical sensitivity. In addition to the experimental protocol, we also introduce here KAS-pipe, a user-friendly integrative data analysis pipeline for KAS-seq.
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21
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Thomsen I, Kunowska N, de Souza R, Moody AM, Crawford G, Wang YF, Khadayate S, Whilding C, Strid J, Karimi MM, Barr AR, Dillon N, Sabbattini P. RUNX1 Regulates a Transcription Program That Affects the Dynamics of Cell Cycle Entry of Naive Resting B Cells. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2021; 207:2976-2991. [PMID: 34810221 PMCID: PMC8675107 DOI: 10.4049/jimmunol.2001367] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Accepted: 09/28/2021] [Indexed: 11/19/2022]
Abstract
RUNX1 is a transcription factor that plays key roles in hematopoietic development and in hematopoiesis and lymphopoiesis. In this article, we report that RUNX1 regulates a gene expression program in naive mouse B cells that affects the dynamics of cell cycle entry in response to stimulation of the BCR. Conditional knockout of Runx1 in mouse resting B cells resulted in accelerated entry into S-phase after BCR engagement. Our results indicate that Runx1 regulates the cyclin D2 (Ccnd2) gene, the immediate early genes Fosl2, Atf3, and Egr2, and the Notch pathway gene Rbpj in mouse B cells, reducing the rate at which transcription of these genes increases after BCR stimulation. RUNX1 interacts with the chromatin remodeler SNF-2-related CREB-binding protein activator protein (SRCAP), recruiting it to promoter and enhancer regions of the Ccnd2 gene. BCR-mediated activation triggers switching between binding of RUNX1 and its paralog RUNX3 and between SRCAP and the switch/SNF remodeling complex member BRG1. Binding of BRG1 is increased at the Ccnd2 and Rbpj promoters in the Runx1 knockout cells after BCR stimulation. We also find that RUNX1 exerts positive or negative effects on a number of genes that affect the activation response of mouse resting B cells. These include Cd22 and Bank1, which act as negative regulators of the BCR, and the IFN receptor subunit gene Ifnar1 The hyperresponsiveness of the Runx1 knockout B cells to BCR stimulation and its role in regulating genes that are associated with immune regulation suggest that RUNX1 could be involved in regulating B cell tolerance.
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Affiliation(s)
- Inesa Thomsen
- Gene Regulation and Chromatin Group, MRC London Institute of Medical Sciences, London, United Kingdom
| | - Natalia Kunowska
- Gene Regulation and Chromatin Group, MRC London Institute of Medical Sciences, London, United Kingdom
| | - Roshni de Souza
- Gene Regulation and Chromatin Group, MRC London Institute of Medical Sciences, London, United Kingdom
| | - Anne-Marie Moody
- Gene Regulation and Chromatin Group, MRC London Institute of Medical Sciences, London, United Kingdom
| | - Greg Crawford
- Department of Immunology and Inflammation, Imperial College London, London, United Kingdom
| | - Yi-Fang Wang
- Bioinformatics and Computing, MRC London Institute of Medical Sciences, London, United Kingdom
| | - Sanjay Khadayate
- Bioinformatics and Computing, MRC London Institute of Medical Sciences, London, United Kingdom
| | - Chad Whilding
- Microscopy Facility, MRC London Institute of Medical Sciences, London, United Kingdom
| | - Jessica Strid
- Department of Immunology and Inflammation, Imperial College London, London, United Kingdom
| | - Mohammad M Karimi
- Bioinformatics and Computing, MRC London Institute of Medical Sciences, London, United Kingdom
- Comprehensive Cancer Centre, School of Cancer & Pharmaceutical Sciences, King's College London, London, United Kingdom
| | - Alexis R Barr
- Cell Cycle Control Group, MRC London Institute of Medical Sciences, London, United Kingdom; and
- Institute of Clinical Sciences, Imperial College London, London, United Kingdom
| | - Niall Dillon
- Gene Regulation and Chromatin Group, MRC London Institute of Medical Sciences, London, United Kingdom;
- Institute of Clinical Sciences, Imperial College London, London, United Kingdom
| | - Pierangela Sabbattini
- Gene Regulation and Chromatin Group, MRC London Institute of Medical Sciences, London, United Kingdom;
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22
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Biochemical Analysis of Leukocytes after In Vitro and In Vivo Activation with Bacterial and Fungal Pathogens Using Raman Spectroscopy. Int J Mol Sci 2021; 22:ijms221910481. [PMID: 34638822 PMCID: PMC8508974 DOI: 10.3390/ijms221910481] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Revised: 09/14/2021] [Accepted: 09/23/2021] [Indexed: 11/25/2022] Open
Abstract
Biochemical information from activated leukocytes provide valuable diagnostic information. In this study, Raman spectroscopy was applied as a label-free analytical technique to characterize the activation pattern of leukocyte subpopulations in an in vitro infection model. Neutrophils, monocytes, and lymphocytes were isolated from healthy volunteers and stimulated with heat-inactivated clinical isolates of Candida albicans, Staphylococcus aureus, and Klebsiella pneumoniae. Binary classification models could identify the presence of infection for monocytes and lymphocytes, classify the type of infection as bacterial or fungal for neutrophils, monocytes, and lymphocytes and distinguish the cause of infection as Gram-negative or Gram-positive bacteria in the monocyte subpopulation. Changes in single-cell Raman spectra, upon leukocyte stimulation, can be explained with biochemical changes due to the leukocyte’s specific reaction to each type of pathogen. Raman spectra of leukocytes from the in vitro infection model were compared with spectra from leukocytes of patients with infection (DRKS-ID: DRKS00006265) with the same pathogen groups, and a good agreement was revealed. Our study elucidates the potential of Raman spectroscopy-based single-cell analysis for the differentiation of circulating leukocyte subtypes and identification of the infection by probing the molecular phenotype of those cells.
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23
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Scarpa M, Kapoor S, Tvedte ES, Doshi KA, Zou YS, Singh P, Lee JK, Chatterjee A, Ali MKM, Bromley RE, Hotopp JCD, Rassool FV, Baer MR. Pim kinase inhibitor co-treatment decreases alternative non-homologous end-joining DNA repair and genomic instability induced by topoisomerase 2 inhibitors in cells with FLT3 internal tandem duplication. Oncotarget 2021; 12:1763-1779. [PMID: 34504649 PMCID: PMC8416564 DOI: 10.18632/oncotarget.28042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Accepted: 07/28/2021] [Indexed: 01/11/2023] Open
Abstract
Acute myeloid leukemia (AML) with fms-like tyrosine kinase 3 internal tandem duplication (FLT3-ITD) relapses with new chromosome abnormalities following chemotherapy, implicating genomic instability. Error-prone alternative non-homologous end-joining (Alt-NHEJ) DNA double-strand break (DSB) repair is upregulated in FLT3-ITD-expresssing cells, driven by c-Myc. The serine/threonine kinase Pim-1 is upregulated downstream of FLT3-ITD, and inhibiting Pim increases topoisomerase 2 (TOP2) inhibitor chemotherapy drug induction of DNA DSBs and apoptosis. We hypothesized that Pim inhibition increases DNA DSBs by downregulating Alt-NHEJ, also decreasing genomic instability. Alt-NHEJ activity, measured with a green fluorescent reporter construct, increased in FLT3-ITD-transfected Ba/F3-ITD cells treated with TOP2 inhibitors, and this increase was abrogated by Pim kinase inhibitor AZD1208 co-treatment. TOP2 inhibitor and AZD1208 co-treatment downregulated cellular and nuclear expression of c-Myc and Alt-NHEJ repair pathway proteins DNA polymerase θ, DNA ligase 3 and XRCC1 in FLT3-ITD cell lines and AML patient blasts. ALT-NHEJ protein downregulation was preceded by c-Myc downregulation, inhibited by c-Myc overexpression and induced by c-Myc knockdown or inhibition. TOP2 inhibitor treatment increased chromosome breaks in metaphase spreads in FLT3-ITD-expressing cells, and AZD1208 co-treatment abrogated these increases. Thus Pim kinase inhibitor co-treatment both enhances TOP2 inhibitor cytotoxicity and decreases TOP2 inhibitor-induced genomic instability in cells with FLT3-ITD.
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Affiliation(s)
- Mario Scarpa
- University of Maryland Greenebaum Comprehensive Cancer Center, Baltimore, MD, USA
- Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Shivani Kapoor
- University of Maryland Greenebaum Comprehensive Cancer Center, Baltimore, MD, USA
| | | | - Kshama A. Doshi
- University of Maryland Greenebaum Comprehensive Cancer Center, Baltimore, MD, USA
| | - Ying S. Zou
- University of Maryland Greenebaum Comprehensive Cancer Center, Baltimore, MD, USA
- Department of Pathology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Prerna Singh
- University of Maryland Greenebaum Comprehensive Cancer Center, Baltimore, MD, USA
| | - Jonelle K. Lee
- University of Maryland Greenebaum Comprehensive Cancer Center, Baltimore, MD, USA
| | - Aditi Chatterjee
- University of Maryland Greenebaum Comprehensive Cancer Center, Baltimore, MD, USA
- Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Moaath K. Mustafa Ali
- University of Maryland Greenebaum Comprehensive Cancer Center, Baltimore, MD, USA
- Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, USA
| | | | - Julie C. Dunning Hotopp
- University of Maryland Greenebaum Comprehensive Cancer Center, Baltimore, MD, USA
- Institute for Genome Sciences, Baltimore, MD, USA
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Feyruz V. Rassool
- University of Maryland Greenebaum Comprehensive Cancer Center, Baltimore, MD, USA
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Maria R. Baer
- University of Maryland Greenebaum Comprehensive Cancer Center, Baltimore, MD, USA
- Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, USA
- Veterans Affairs Medical Center, Baltimore, MD, USA
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24
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Kumari R, Roy U, Desai S, Nilavar NM, Van Nieuwenhuijze A, Paranjape A, Radha G, Bawa P, Srivastava M, Nambiar M, Balaji KN, Liston A, Choudhary B, Raghavan SC. MicroRNA miR-29c regulates RAG1 expression and modulates V(D)J recombination during B cell development. Cell Rep 2021; 36:109390. [PMID: 34260911 DOI: 10.1016/j.celrep.2021.109390] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Revised: 03/07/2021] [Accepted: 06/22/2021] [Indexed: 12/13/2022] Open
Abstract
Recombination activating genes (RAGs), consisting of RAG1 and RAG2, are stringently regulated lymphoid-specific genes, which initiate V(D)J recombination in developing lymphocytes. We report the regulation of RAG1 through a microRNA (miRNA), miR-29c, in a B cell stage-specific manner in mice and humans. Various lines of experimentation, including CRISPR-Cas9 genome editing, demonstrate the target specificity and direct interaction of miR-29c to RAG1. Modulation of miR-29c levels leads to change in V(D)J recombination efficiency in pre-B cells. The miR-29c expression is inversely proportional to RAG1 in a B cell developmental stage-specific manner, and miR-29c null mice exhibit a reduction in mature B cells. A negative correlation of miR-29c and RAG1 levels is also observed in leukemia patients, suggesting the potential use of miR-29c as a biomarker and a therapeutic target. Thus, our results reveal the role of miRNA in the regulation of RAG1 and its relevance in cancer.
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Affiliation(s)
- Rupa Kumari
- Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India
| | - Urbi Roy
- Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India
| | - Sagar Desai
- Institute of Bioinformatics and Applied Biotechnology, Bangalore 560100, India; Manipal Academy of Higher Education, Manipal, Karnataka 576104, India
| | - Namrata M Nilavar
- Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India
| | | | - Amita Paranjape
- Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India
| | - Gudapureddy Radha
- Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India
| | - Pushpinder Bawa
- Institute of Bioinformatics and Applied Biotechnology, Bangalore 560100, India
| | - Mrinal Srivastava
- TIFR Centre for Interdisciplinary Sciences, Tata Institute of Fundamental Research (TIFR), Hyderabad 500046, India
| | - Mridula Nambiar
- Department of Biology, Indian Institute of Science Education and Research, Pune, India
| | | | - Adrian Liston
- Immunology Programme, Babraham Institute, Cambridge, United Kingdom
| | - Bibha Choudhary
- Institute of Bioinformatics and Applied Biotechnology, Bangalore 560100, India.
| | - Sathees C Raghavan
- Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India.
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25
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Krassovsky K, Ghosh RP, Meyer BJ. Genome-wide profiling reveals functional interplay of DNA sequence composition, transcriptional activity, and nucleosome positioning in driving DNA supercoiling and helix destabilization in C. elegans. Genome Res 2021; 31:1187-1202. [PMID: 34168009 PMCID: PMC8256864 DOI: 10.1101/gr.270082.120] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Accepted: 05/25/2021] [Indexed: 12/11/2022]
Abstract
DNA topology and alternative DNA structures are implicated in regulating diverse biological processes. Although biomechanical properties of these structures have been studied extensively in vitro, characterization in vivo, particularly in multicellular organisms, is limited. We devised new methods to map DNA supercoiling and single-stranded DNA in Caenorhabditis elegans embryos and diapause larvae. To map supercoiling, we quantified the incorporation of biotinylated psoralen into DNA using high-throughput sequencing. To map single-stranded DNA, we combined permanganate treatment with genome-wide sequencing of induced double-stranded breaks. We found high levels of negative supercoiling at transcription start sites (TSSs) in embryos. GC-rich regions flanked by a sharp GC-to-AT transition delineate boundaries of supercoil propagation. In contrast to TSSs in embryos, TSSs in diapause larvae showed dramatic reductions in negative supercoiling without concomitant attenuation of transcription, suggesting developmental-stage-specific regulation. To assess whether alternative DNA structures control chromosome architecture and gene expression, we examined DNA supercoiling in the context of X-Chromosome dosage compensation. We showed that the condensin dosage compensation complex creates negative supercoils locally at its highest-occupancy binding sites but found no evidence for large-scale supercoiling domains along X Chromosomes. In contrast to transcription-coupled negative supercoiling, single-strandedness, which is most pronounced at transcript end sites, is dependent on high AT content and symmetrically positioned nucleosomes. We propose that sharp transitions in sequence composition at functional genomic elements constitute a common regulatory code and that DNA structure and propagation of torsional stress at regulatory elements are critical parameters in shaping important developmental events.
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Affiliation(s)
- Kristina Krassovsky
- Department of Molecular and Cell Biology, University of California, Berkeley, California 94720-3204, USA
| | - Rajarshi P Ghosh
- Department of Molecular and Cell Biology, University of California, Berkeley, California 94720-3204, USA
- Howard Hughes Medical Institute, University of California, Berkeley, California 94720-3204, USA
| | - Barbara J Meyer
- Department of Molecular and Cell Biology, University of California, Berkeley, California 94720-3204, USA
- Howard Hughes Medical Institute, University of California, Berkeley, California 94720-3204, USA
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26
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Schilbach S, Aibara S, Dienemann C, Grabbe F, Cramer P. Structure of RNA polymerase II pre-initiation complex at 2.9 Å defines initial DNA opening. Cell 2021; 184:4064-4072.e28. [PMID: 34133942 DOI: 10.1016/j.cell.2021.05.012] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Revised: 04/13/2021] [Accepted: 05/10/2021] [Indexed: 01/05/2023]
Abstract
Transcription initiation requires assembly of the RNA polymerase II (Pol II) pre-initiation complex (PIC) and opening of promoter DNA. Here, we present the long-sought high-resolution structure of the yeast PIC and define the mechanism of initial DNA opening. We trap the PIC in an intermediate state that contains half a turn of open DNA located 30-35 base pairs downstream of the TATA box. The initially opened DNA region is flanked and stabilized by the polymerase "clamp head loop" and the TFIIF "charged region" that both contribute to promoter-initiated transcription. TFIIE facilitates initiation by buttressing the clamp head loop and by regulating the TFIIH translocase. The initial DNA bubble is then extended in the upstream direction, leading to the open promoter complex and enabling start-site scanning and RNA synthesis. This unique mechanism of DNA opening may permit more intricate regulation than in the Pol I and Pol III systems.
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Affiliation(s)
- Sandra Schilbach
- Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Shintaro Aibara
- Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Christian Dienemann
- Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Frauke Grabbe
- Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Patrick Cramer
- Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany.
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27
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Three-dimensional genome rewiring during the development of antibody-secreting cells. Biochem Soc Trans 2021; 48:1109-1119. [PMID: 32453419 PMCID: PMC7329350 DOI: 10.1042/bst20191104] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 04/26/2020] [Accepted: 04/28/2020] [Indexed: 01/08/2023]
Abstract
The development of B lymphocytes into antibody-secreting plasma cells is central to the adaptive immune system in that it confers protective and specific antibody response against invading pathogen. This developmental process involves extensive morphological and functional alterations that begin early after antigenic stimulation. These include chromatin restructuring that is critical in regulating gene expression, DNA rearrangement and other cellular processes. Here we outline the recent understanding of the three-dimensional architecture of the genome, specifically focused on its contribution to the process of B cell activation and terminal differentiation into antibody-secreting cells.
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28
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Wiggins KJ, Scharer CD. Roadmap to a plasma cell: Epigenetic and transcriptional cues that guide B cell differentiation. Immunol Rev 2020; 300:54-64. [PMID: 33278036 DOI: 10.1111/imr.12934] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2020] [Revised: 11/06/2020] [Accepted: 11/16/2020] [Indexed: 12/11/2022]
Abstract
Antibody-secreting cells (ASCs) or plasma cells secrete antibodies and form a cornerstone of humoral immunity. B cells that receive activation signals in the presence or absence of T cells initiate a differentiation program that requires epigenetic and transcriptional reprogramming in order to ultimately form ASC. Reprogramming is accomplished through the interplay of transcription factors that initiate gene expression programs and epigenetic mechanisms that maintain these programs and cell fates. An important consideration is that all of these factors are operating in the context of cell division. Recent technical advances now allow mechanistic studies to move beyond genetic studies to identify the promoters and enhancer repertoires that are regulated by epigenetic mechanisms and transcription factors in rare cell types and differentiation stages in vivo. This review will detail efforts to integrate transcriptional and epigenetic changes during B cell differentiation with cell division in vivo. What has emerged is a multiphased differentiation model that requires distinct transcription factors and epigenetic programs at each step. The identification of markers that define each phase will help facilitate the manipulation of B cell differentiation for vaccine development or to treat diseases where antibodies are a component.
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Affiliation(s)
- Keenan J Wiggins
- Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, GA, USA
| | - Christopher D Scharer
- Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, GA, USA
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29
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Szlachta K, Manukyan A, Raimer HM, Singh S, Salamon A, Guo W, Lobachev KS, Wang YH. Topoisomerase II contributes to DNA secondary structure-mediated double-stranded breaks. Nucleic Acids Res 2020; 48:6654-6671. [PMID: 32501506 PMCID: PMC7337936 DOI: 10.1093/nar/gkaa483] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 05/20/2020] [Accepted: 06/01/2020] [Indexed: 12/12/2022] Open
Abstract
DNA double-stranded breaks (DSBs) trigger human genome instability, therefore identifying what factors contribute to DSB induction is critical for our understanding of human disease etiology. Using an unbiased, genome-wide approach, we found that genomic regions with the ability to form highly stable DNA secondary structures are enriched for endogenous DSBs in human cells. Human genomic regions predicted to form non-B-form DNA induced gross chromosomal rearrangements in yeast and displayed high indel frequency in human genomes. The extent of instability in both analyses is in concordance with the structure forming ability of these regions. We also observed an enrichment of DNA secondary structure-prone sites overlapping transcription start sites (TSSs) and CCCTC-binding factor (CTCF) binding sites, and uncovered an increase in DSBs at highly stable DNA secondary structure regions, in response to etoposide, an inhibitor of topoisomerase II (TOP2) re-ligation activity. Importantly, we found that TOP2 deficiency in both yeast and human leads to a significant reduction in DSBs at structure-prone loci, and that sites of TOP2 cleavage have a greater ability to form highly stable DNA secondary structures. This study reveals a direct role for TOP2 in generating secondary structure-mediated DNA fragility, advancing our understanding of mechanisms underlying human genome instability.
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Affiliation(s)
- Karol Szlachta
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA 22908-0733, USA
| | - Arkadi Manukyan
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA 22908-0733, USA
| | - Heather M Raimer
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA 22908-0733, USA
| | - Sandeep Singh
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA 22908-0733, USA
| | - Anita Salamon
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA 22908-0733, USA
| | - Wenying Guo
- School of Biological Sciences and Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Kirill S Lobachev
- School of Biological Sciences and Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Yuh-Hwa Wang
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA 22908-0733, USA
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30
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Li Z, Zhao S, Nelakanti RV, Lin K, Wu TP, Alderman MH, Guo C, Wang P, Zhang M, Min W, Jiang Z, Wang Y, Li H, Xiao AZ. N 6-methyladenine in DNA antagonizes SATB1 in early development. Nature 2020; 583:625-630. [PMID: 32669713 PMCID: PMC8596487 DOI: 10.1038/s41586-020-2500-9] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2019] [Accepted: 05/04/2020] [Indexed: 02/08/2023]
Abstract
The recent discovery of N6-mA in mammalian genomes suggests that it may serve as an epigenetic regulatory mechanism1. However, the biological role of N6-mA and molecular pathways exerting its function remain elusive. Herein, we demonstrate that N6-mA plays a critical role in changing the epigenetic landscape during cell fate transitions in early development. We found that N6-mA is upregulated during trophoblast stem cell development, specifically at Stress Induced DNA Double Helix Destabilization (SIDD) regions2-4. It is well-known that SIDD regions are conducive to topological stress-induced double helix unpairing and play critical roles in organizing large-scale chromatin structures3,5,6. We demonstrated that the presence of N6-mA abolishes (>500-fold) the in vitro interactions between SIDD and SATB1, a critical chromatin organizer interacting with SIDD regions; N6-mA deposition also effectively antagonizes SATB1 function in vivo by preventing its binding to chromatin. Concordantly, N6-mA functions at the boundaries between eu-/hetero- chromatin to restrict the spreading of euchromatin. N6-mA mediated repression is critical for gene regulation during trophoblast development in cell culture models and in vivo. Overall, our study discovers an unexpected molecular mechanism for N6-mA function via SATB1, and reveals surprising connections between DNA modification, DNA secondary structures and large chromatin domains in early embryonic development.
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Affiliation(s)
- Zheng Li
- Department of Genetics and Yale Stem Cell Center, Yale School of Medicine, New Haven, CT, USA
| | - Shuai Zhao
- MOE Key Laboratory of Protein Sciences, Beijing Advanced Innovation Center for Structural Biology, Beijing Frontier Research Center for Biological Structure, Tsinghua-Peking Joint Center for Life Sciences, Department of Basic Medical Sciences, School of Medicine, Tsinghua University, Beijing, China
| | - Raman V Nelakanti
- Department of Genetics and Yale Stem Cell Center, Yale School of Medicine, New Haven, CT, USA
| | - Kaixuan Lin
- Department of Genetics and Yale Stem Cell Center, Yale School of Medicine, New Haven, CT, USA
| | - Tao P Wu
- Department of Genetics and Yale Stem Cell Center, Yale School of Medicine, New Haven, CT, USA.,Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Myles H Alderman
- Department of Genetics and Yale Stem Cell Center, Yale School of Medicine, New Haven, CT, USA
| | - Cheng Guo
- Department of Chemistry, University of California, Riverside, CA, USA.,Cancer Institute, Key Laboratory of Cancer Prevention and Intervention, China National Ministry of Education, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Pengcheng Wang
- Department of Chemistry, University of California, Riverside, CA, USA
| | - Min Zhang
- MOE Key Laboratory of Protein Sciences, Beijing Advanced Innovation Center for Structural Biology, Beijing Frontier Research Center for Biological Structure, Tsinghua-Peking Joint Center for Life Sciences, Department of Basic Medical Sciences, School of Medicine, Tsinghua University, Beijing, China
| | - Wang Min
- Interdepartmental Program in Vascular Biology and Therapeutics, Department of Pathology, Yale University School of Medicine, New Haven, CT, USA
| | - Zongliang Jiang
- School of Animal Sciences, AgCenter, Louisiana State University, Baton Rouge, LA, USA
| | - Yinsheng Wang
- Department of Chemistry, University of California, Riverside, CA, USA
| | - Haitao Li
- MOE Key Laboratory of Protein Sciences, Beijing Advanced Innovation Center for Structural Biology, Beijing Frontier Research Center for Biological Structure, Tsinghua-Peking Joint Center for Life Sciences, Department of Basic Medical Sciences, School of Medicine, Tsinghua University, Beijing, China.
| | - Andrew Z Xiao
- Department of Genetics and Yale Stem Cell Center, Yale School of Medicine, New Haven, CT, USA.
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31
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Wolf T, Jin W, Zoppi G, Vogel IA, Akhmedov M, Bleck CKE, Beltraminelli T, Rieckmann JC, Ramirez NJ, Benevento M, Notarbartolo S, Bumann D, Meissner F, Grimbacher B, Mann M, Lanzavecchia A, Sallusto F, Kwee I, Geiger R. Dynamics in protein translation sustaining T cell preparedness. Nat Immunol 2020; 21:927-937. [PMID: 32632289 PMCID: PMC7610365 DOI: 10.1038/s41590-020-0714-5] [Citation(s) in RCA: 87] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Accepted: 05/19/2020] [Indexed: 12/16/2022]
Abstract
In response to pathogenic threats, naïve T cells rapidly transition from a quiescent to activated state, yet the underlying mechanisms are incompletely understood. Using a pulsed SILAC approach, we investigated the dynamics of mRNA translation kinetics and protein turnover in human naïve and activated T cells. Our datasets uncovered that transcription factors maintaining T cell quiescence had constitutively high turnover, which facilitated their depletion upon activation. Furthermore, naïve T cells maintained a surprisingly large number of idling ribosomes as well as 242 repressed mRNA species and a reservoir of glycolytic enzymes. These components were rapidly engaged following stimulation, promoting an immediate translational and glycolytic switch to ramp up the T cell activation program. Our data elucidate new insights into how T cells maintain a prepared state to mount a rapid immune response, and provide a resource of protein turnover, absolute translation kinetics and protein synthesis rates in T cells (www.immunomics.ch).
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Affiliation(s)
- Tobias Wolf
- Institute for Research in Biomedicine, Università della Svizzera italiana, Bellinzona, Switzerland.,Institute of Microbiology, ETH Zürich, Zurich, Switzerland
| | - Wenjie Jin
- Institute for Research in Biomedicine, Università della Svizzera italiana, Bellinzona, Switzerland
| | - Giada Zoppi
- Institute for Research in Biomedicine, Università della Svizzera italiana, Bellinzona, Switzerland
| | - Ian A Vogel
- Institute for Research in Biomedicine, Università della Svizzera italiana, Bellinzona, Switzerland
| | - Murodzhon Akhmedov
- Institute for Research in Biomedicine, Università della Svizzera italiana, Bellinzona, Switzerland
| | | | - Tim Beltraminelli
- Institute for Research in Biomedicine, Università della Svizzera italiana, Bellinzona, Switzerland
| | - Jan C Rieckmann
- Experimental Systems Immunology, Max Planck Institute of Biochemistry, Munich, Germany
| | - Neftali J Ramirez
- Institute for Immunodeficiency, Center for Chronic Immunodeficiency, Medical Center, Faculty of Medicine, Albert-Ludwigs-University of Freiburg, Freiburg, Germany.,Integrated Research Training Group (IRTG) Medical Epigenetics, Collaborative Research Centre 992, Freiburg, Germany
| | - Marco Benevento
- Institute for Research in Biomedicine, Università della Svizzera italiana, Bellinzona, Switzerland
| | - Samuele Notarbartolo
- Institute for Research in Biomedicine, Università della Svizzera italiana, Bellinzona, Switzerland
| | - Dirk Bumann
- Biozentrum, University of Basel, Basel, Switzerland
| | - Felix Meissner
- Experimental Systems Immunology, Max Planck Institute of Biochemistry, Munich, Germany.,Institute of Innate Immunity, Department of Systems Immunology and Proteomics, Medical Faculty, University of Bonn, Bonn, Germany
| | - Bodo Grimbacher
- Institute for Immunodeficiency, Center for Chronic Immunodeficiency, Medical Center, Faculty of Medicine, Albert-Ludwigs-University of Freiburg, Freiburg, Germany.,DZIF - German Center for Infection Research, Satellite Center Freiburg, Freiburg, Germany.,CIBSS - Centre for Integrative Biological Signalling Studies, Albert-Ludwigs University, Freiburg, Germany.,RESIST - Cluster of Excellence 2155 to Hanover Medical School, Satellite Center Freiburg, Freiburg, Germany
| | - Matthias Mann
- Department of Proteomics and Signal Transduction, Max Planck Institute of Biochemistry, Munich, Germany
| | - Antonio Lanzavecchia
- Institute for Research in Biomedicine, Università della Svizzera italiana, Bellinzona, Switzerland
| | - Federica Sallusto
- Institute for Research in Biomedicine, Università della Svizzera italiana, Bellinzona, Switzerland.,Institute of Microbiology, ETH Zürich, Zurich, Switzerland
| | - Ivo Kwee
- Institute for Research in Biomedicine, Università della Svizzera italiana, Bellinzona, Switzerland
| | - Roger Geiger
- Institute for Research in Biomedicine, Università della Svizzera italiana, Bellinzona, Switzerland.
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32
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Dang J, Xu Z, Xu A, Liu Y, Fu Q, Wang J, Huang F, Zheng Y, Qi G, Sun B, Bellanti JA, Kandalam U, Emam HA, Jarjour W, Zheng SG. Human gingiva-derived mesenchymal stem cells are therapeutic in lupus nephritis through targeting of CD39 -CD73 signaling pathway. J Autoimmun 2020; 113:102491. [PMID: 32565049 DOI: 10.1016/j.jaut.2020.102491] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Revised: 04/30/2020] [Accepted: 05/18/2020] [Indexed: 12/21/2022]
Abstract
Cell specific and cytokine targeted therapeutics have underperformed in systemic lupus erythematosus (SLE). Mesenchymal stem cells (MSCs) have emerged as a novel therapy to address the dysregulation in autoimmune diseases but also have limitations. Human gingiva derived MSCs (GMSCs) are superior in regulating immune responses. Here, we demonstrate that the adoptive transfer of GMSCs homes to and maintains in the kidney and has a robust therapeutic effect in a spontaneous lupus nephritis model. Specifically, GMSCs limits the development of autoantibodies as well as proteinuria, decreases the frequency of plasma cells and lupus nephritis histopathological scores by directly suppressing B cells activation, proliferation and differentiation. The blockage of CD39-CD73 pathway dramatically abrogates the suppressive capacities of GMSCs in vitro and in vivo and highlights the significance of this signaling pathway in SLE. Collectively, manipulation of GMSCs provides a promising strategy for the treatment of patients with SLE and other autoimmune diseases.
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Affiliation(s)
- Junlong Dang
- Department of Clinical Immunology, Third Affiliated Hospital at Sun Yat-sen University, Guangzhou, China; Division of Rheumatology, Department of Medicine, Penn State College of Medicine, Hershey, PA, USA
| | - Zhenjian Xu
- Division of Rheumatology, Department of Medicine, Penn State College of Medicine, Hershey, PA, USA; Department of Nephrology, Sun Yat-sen Memorial Hospital of Sun Yat-sen University, Guangzhou, China
| | - Anping Xu
- Department of Nephrology, Sun Yat-sen Memorial Hospital of Sun Yat-sen University, Guangzhou, China
| | - Yan Liu
- Department of Clinical Immunology, Third Affiliated Hospital at Sun Yat-sen University, Guangzhou, China
| | - Qingling Fu
- Otorhinolaryngology Department, The First Affiliated Hospital of Sun Yat-Sen University, Guangzhou, China
| | - Julie Wang
- Division of Immunology and Rheumatology, Department of Internal Medicine, Ohio State University College of Medicine, USA
| | - Feng Huang
- Department of Clinical Immunology, Third Affiliated Hospital at Sun Yat-sen University, Guangzhou, China
| | - Yuejuan Zheng
- Center for Traditional Chinese Medicine and Immunology Research, School of Basic Medical Sciences, Shanghai University of Traditional Chinese Medicine, Shanghai, China.
| | - Guangying Qi
- Guangxi State Key Lab, Guilin College of Medicine, Guilin, China
| | - Boqing Sun
- Department of Allergy and Clinical Immunology, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Joseph A Bellanti
- Departments of Pediatrics and Microbiology-Immunology, Georgetown University Medical Center, Washington DC, USA
| | - Umadevi Kandalam
- Department of Pediatric Dentistry, College of Dental Medicine, Nova Southeastern University, Davie, FL, USA
| | - Hany A Emam
- Department of Oral & Maxillofacial Surgery, The Ohio State University, Columbus, USA
| | - Wael Jarjour
- Division of Immunology and Rheumatology, Department of Internal Medicine, Ohio State University College of Medicine, USA
| | - Song Guo Zheng
- Division of Immunology and Rheumatology, Department of Internal Medicine, Ohio State University College of Medicine, USA.
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33
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Kouzine F, Wojtowicz D, Yamane A, Casellas R, Przytycka TM, Levens DL. In Vivo Chemical Probing for G-Quadruplex Formation. Methods Mol Biol 2020; 2035:369-382. [PMID: 31444763 DOI: 10.1007/978-1-4939-9666-7_23] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
While DNA inside the cells is predominantly canonical right-handed double helix, guanine-rich DNAs have potential to fold into four-stranded structures that contain stacks of G-quartets (G4 DNA quadruplex). Genome sequencing has revealed G4 sequences tend to localize at the gene control regions, especially in the promoters of oncogenes. A growing body of evidence indicates that G4 DNA quadruplexes might have important regulatory roles in genome function, highlighting the need for techniques to detect genome-wide folding of DNA into this structure. Potassium permanganate in vivo treatment of cells results in oxidizing of nucleotides in single-stranded DNA regions that accompany G4 DNA quadruplexes formation, providing an excellent probe for the conformational state of DNA inside the living cells. Here, we describe a permanganate-based methodology to detect G4 DNA quadruplex, genome-wide. This methodology combined with high-throughput sequencing provides a snapshot of the DNA conformation over the whole genome in vivo.
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Affiliation(s)
- Fedor Kouzine
- Laboratory of Pathology, National Cancer Institute, National Institutes of Health (USA), Bethesda, MD, USA
| | - Damian Wojtowicz
- Laboratory of Pathology, National Cancer Institute, National Institutes of Health (USA), Bethesda, MD, USA
| | - Arito Yamane
- Laboratory of Pathology, National Cancer Institute, National Institutes of Health (USA), Bethesda, MD, USA
| | - Rafael Casellas
- Laboratory of Pathology, National Cancer Institute, National Institutes of Health (USA), Bethesda, MD, USA
| | - Teresa M Przytycka
- Laboratory of Pathology, National Cancer Institute, National Institutes of Health (USA), Bethesda, MD, USA
| | - David L Levens
- Laboratory of Pathology, National Cancer Institute, National Institutes of Health (USA), Bethesda, MD, USA.
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34
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Kethoxal-assisted single-stranded DNA sequencing captures global transcription dynamics and enhancer activity in situ. Nat Methods 2020; 17:515-523. [PMID: 32251394 PMCID: PMC7205578 DOI: 10.1038/s41592-020-0797-9] [Citation(s) in RCA: 54] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Accepted: 03/02/2020] [Indexed: 02/06/2023]
Abstract
Transcription is a highly dynamic process that generates single-stranded DNA (ssDNA) in the genome as ‘transcription bubbles’. Here we describe a kethoxal-assisted single-stranded DNA sequencing (KAS-seq) approach, based on the fast and specific reaction between N3-kethoxal and guanines in ssDNA in live cells and mouse tissues. KAS-seq enables rapid (within 5 min), sensitive, and genome-wide capture and mapping of ssDNA produced by transcriptionally active RNA polymerases or other processes in situ by using as few as 1,000 cells. KAS-seq defines a group of enhancers that are single-stranded, which enrich unique sequence motifs and are associated with specific transcription factor binding and more enhancer-promotor interactions. Under protein condensation inhibition conditions, KAS-seq uncovers a rapid release of RNA polymerase II (Pol II) from a group of promotors. KAS-seq thus facilitates fast, comprehensive, and accurate analysis of transcription dynamics and enhancer activities simultaneously in a low input and high-throughput manner.
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35
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Human T-Cell Lymphotropic Virus Type 1 Transactivator Tax Exploits the XPB Subunit of TFIIH during Viral Transcription. J Virol 2020; 94:JVI.02171-19. [PMID: 32024775 DOI: 10.1128/jvi.02171-19] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2019] [Accepted: 01/29/2020] [Indexed: 01/14/2023] Open
Abstract
Human T-cell lymphotropic virus type 1 (HTLV-1) Tax oncoprotein is required for viral gene expression. Tax transactivates the viral promoter by recruiting specific transcription factors but also by interfering with general transcription factors involved in the preinitiation step, such as TFIIA and TFIID. However, data are lacking regarding Tax interplay with TFIIH, which intervenes during the last step of preinitiation. We previously reported that XPB, the TFIIH subunit responsible for promoter opening and promoter escape, is required for Tat-induced human-immunodeficiency virus promoter transactivation. Here, we investigated whether XPB may also play a role in HTLV-1 transcription. We report that Tax and XPB directly interact in vitro and that endogenous XPB produced by HTLV-1-infected T cells binds to Tax and is recruited on proviral LTRs. In contrast, XPB recruitment at the LTR is not detected in Tax-negative HTLV-1-infected T cells and is strongly reduced when Tax-induced HTLV-1 LTR transactivation is blocked. XPB overexpression does not affect basal HTLV-1 promoter activation but enhances Tax-mediated transactivation in T cells. Conversely, downregulating XPB strongly reduces Tax-mediated transactivation. Importantly, spironolactone (SP)-mediated inhibition of LTR activation can be rescued by overexpressing XPB but not XPD, another TFIIH subunit. Furthermore, an XPB mutant defective for the ATPase activity responsible for promoter opening does not show rescue of the effect of SP. Finally, XPB downregulation reduces viability of Tax-positive but not Tax-negative HTLV-1-transformed T cell lines. These findings reveal that XPB is a novel cellular cofactor hijacked by Tax to facilitate HTLV-1 transcription.IMPORTANCE HTLV-1 is considered the most potent human oncovirus and is also responsible for severe inflammatory disorders. HTLV-1 transcription is undertaken by RNA polymerase II and is controlled by the viral oncoprotein Tax. Tax transactivates the viral promoter first via the recruitment of CREB and its cofactors to the long terminal repeat (LTR). However, how Tax controls subsequent steps of the transcription process remains unclear. In this study, we explore the link between Tax and the XPB subunit of TFIIH that governs, via its ATPase activity, the promoter-opening step of transcription. We demonstrate that XPB is a novel physical and functional partner of Tax, recruited on HTLV-1 LTR, and required for viral transcription. These findings extend the mechanism of Tax transactivation to the recruitment of TFIIH and reinforce the link between XPB and transactivator-induced viral transcription.
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36
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Talbert PB, Henikoff S. What makes a centromere? Exp Cell Res 2020; 389:111895. [PMID: 32035948 DOI: 10.1016/j.yexcr.2020.111895] [Citation(s) in RCA: 87] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2019] [Revised: 01/18/2020] [Accepted: 02/05/2020] [Indexed: 12/26/2022]
Abstract
Centromeres are the eukaryotic chromosomal sites at which the kinetochore forms and attaches to spindle microtubules to orchestrate chromosomal segregation in mitosis and meiosis. Although centromeres are essential for cell division, their sequences are not conserved and evolve rapidly. Centromeres vary dramatically in size and organization. Here we categorize their diversity and explore the evolutionary forces shaping them. Nearly all centromeres favor AT-rich DNA that is gene-free and transcribed at a very low level. Repair of frequent centromere-proximal breaks probably contributes to their rapid sequence evolution. Point centromeres are only ~125 bp and are specified by common protein-binding motifs, whereas short regional centromeres are 1-5 kb, typically have unique sequences, and may have pericentromeric repeats adapted to facilitate centromere clustering. Transposon-rich centromeres are often ~100-300 kb and are favored by RNAi machinery that silences transposons, by suppression of meiotic crossovers at centromeres, and by the ability of some transposons to target centromeres. Megabase-length satellite centromeres arise in plants and animals with asymmetric female meiosis that creates centromere competition, and favors satellite monomers one or two nucleosomes in length that position and stabilize centromeric nucleosomes. Holocentromeres encompass the length of a chromosome and may differ dramatically between mitosis and meiosis. We propose a model in which low level transcription of centromeres facilitates the formation of non-B DNA that specifies centromeres and promotes loading of centromeric nucleosomes.
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Affiliation(s)
- Paul B Talbert
- Howard Hughes Medical Institute, Fred Hutchinson Cancer Research Center, 1100 Fairview Ave N, Seattle, WA, 98109, USA
| | - Steven Henikoff
- Howard Hughes Medical Institute, Fred Hutchinson Cancer Research Center, 1100 Fairview Ave N, Seattle, WA, 98109, USA.
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37
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Weidlich D, Klostermeier D. Functional interactions between gyrase subunits are optimized in a species-specific manner. J Biol Chem 2020; 295:2299-2312. [PMID: 31953321 DOI: 10.1074/jbc.ra119.010245] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Revised: 01/03/2020] [Indexed: 11/06/2022] Open
Abstract
DNA gyrase is a bacterial DNA topoisomerase that catalyzes ATP-dependent negative DNA supercoiling and DNA decatenation. The enzyme is a heterotetramer comprising two GyrA and two GyrB subunits. Its overall architecture is conserved, but species-specific elements in the two subunits are thought to optimize subunit interaction and enzyme function. Toward understanding the roles of these different elements, we compared the activities of Bacillus subtilis, Escherichia coli, and Mycobacterium tuberculosis gyrases and of heterologous enzymes reconstituted from subunits of two different species. We show that B. subtilis and E. coli gyrases are proficient DNA-stimulated ATPases and efficiently supercoil and decatenate DNA. In contrast, M. tuberculosis gyrase hydrolyzes ATP only slowly and is a poor supercoiling enzyme and decatenase. The heterologous enzymes are generally less active than their homologous counterparts. The only exception is a gyrase reconstituted from mycobacterial GyrA and B. subtilis GyrB, which exceeds the activity of M. tuberculosis gyrase and reaches the activity of the B. subtilis gyrase, indicating that the activities of enzymes containing mycobacterial GyrB are limited by ATP hydrolysis. The activity pattern of heterologous gyrases is in agreement with structural features present: B. subtilis gyrase is a minimal enzyme, and its subunits can functionally interact with subunits from other bacteria. In contrast, the specific insertions in E. coli and mycobacterial gyrase subunits appear to prevent efficient functional interactions with heterologous subunits. Understanding the molecular details of gyrase adaptations to the specific physiological requirements of the respective organism might aid in the development of species-specific gyrase inhibitors.
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Affiliation(s)
- Daniela Weidlich
- Institute for Physical Chemistry, University of Muenster, Corrensstrasse 30, D-48149 Muenster, Germany
| | - Dagmar Klostermeier
- Institute for Physical Chemistry, University of Muenster, Corrensstrasse 30, D-48149 Muenster, Germany.
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38
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Organization and regulation of gene transcription. Nature 2019; 573:45-54. [PMID: 31462772 DOI: 10.1038/s41586-019-1517-4] [Citation(s) in RCA: 343] [Impact Index Per Article: 68.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Accepted: 07/30/2019] [Indexed: 12/18/2022]
Abstract
The regulated transcription of genes determines cell identity and function. Recent structural studies have elucidated mechanisms that govern the regulation of transcription by RNA polymerases during the initiation and elongation phases. Microscopy studies have revealed that transcription involves the condensation of factors in the cell nucleus. A model is emerging for the transcription of protein-coding genes in which distinct transient condensates form at gene promoters and in gene bodies to concentrate the factors required for transcription initiation and elongation, respectively. The transcribing enzyme RNA polymerase II may shuttle between these condensates in a phosphorylation-dependent manner. Molecular principles are being defined that rationalize transcriptional organization and regulation, and that will guide future investigations.
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39
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Lis JT. A 50 year history of technologies that drove discovery in eukaryotic transcription regulation. Nat Struct Mol Biol 2019; 26:777-782. [PMID: 31439942 DOI: 10.1038/s41594-019-0288-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Accepted: 07/26/2019] [Indexed: 01/12/2023]
Abstract
Transcription regulation is critical to organism development and homeostasis. Control of expression of the 20,000 genes in human cells requires many hundreds of proteins acting through sophisticated multistep mechanisms. In this Historical Perspective, I highlight the progress that has been made in elucidating eukaryotic transcriptional mechanisms through an array of disciplines and approaches, and how this concerted effort has been driven by the development of new technologies.
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Affiliation(s)
- John T Lis
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, USA.
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40
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El Khattabi L, Zhao H, Kalchschmidt J, Young N, Jung S, Van Blerkom P, Kieffer-Kwon P, Kieffer-Kwon KR, Park S, Wang X, Krebs J, Tripathi S, Sakabe N, Sobreira DR, Huang SC, Rao SSP, Pruett N, Chauss D, Sadler E, Lopez A, Nóbrega MA, Aiden EL, Asturias FJ, Casellas R. A Pliable Mediator Acts as a Functional Rather Than an Architectural Bridge between Promoters and Enhancers. Cell 2019; 178:1145-1158.e20. [PMID: 31402173 PMCID: PMC7533040 DOI: 10.1016/j.cell.2019.07.011] [Citation(s) in RCA: 131] [Impact Index Per Article: 26.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Revised: 05/24/2019] [Accepted: 07/09/2019] [Indexed: 12/11/2022]
Abstract
While Mediator plays a key role in eukaryotic transcription, little is known about its mechanism of action. This study combines CRISPR-Cas9 genetic screens, degron assays, Hi-C, and cryoelectron microscopy (cryo-EM) to dissect the function and structure of mammalian Mediator (mMED). Deletion analyses in B, T, and embryonic stem cells (ESC) identified a core of essential subunits required for Pol II recruitment genome-wide. Conversely, loss of non-essential subunits mostly affects promoters linked to multiple enhancers. Contrary to current models, however, mMED and Pol II are dispensable to physically tether regulatory DNA, a topological activity requiring architectural proteins. Cryo-EM analysis revealed a conserved core, with non-essential subunits increasing structural complexity of the tail module, a primary transcription factor target. Changes in tail structure markedly increase Pol II and kinase module interactions. We propose that Mediator's structural pliability enables it to integrate and transmit regulatory signals and act as a functional, rather than an architectural bridge, between promoters and enhancers.
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Affiliation(s)
| | - Haiyan Zhao
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical School, Aurora CO 80045, USA
| | | | - Natalie Young
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical School, Aurora CO 80045, USA
| | - Seolkyoung Jung
- Lymphocyte Nuclear Biology, NIAMS, NIH, Bethesda, MD 20892, USA
| | - Peter Van Blerkom
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical School, Aurora CO 80045, USA
| | | | | | - Solji Park
- Lymphocyte Nuclear Biology, NIAMS, NIH, Bethesda, MD 20892, USA
| | - Xiang Wang
- Lymphocyte Nuclear Biology, NIAMS, NIH, Bethesda, MD 20892, USA
| | - Jordan Krebs
- Lymphocyte Nuclear Biology, NIAMS, NIH, Bethesda, MD 20892, USA
| | | | - Noboru Sakabe
- Department of Human Genetics, University of Chicago, Chicago, IL, USA
| | - Débora R Sobreira
- Department of Human Genetics, University of Chicago, Chicago, IL, USA
| | - Su-Chen Huang
- The Center for Genome Architecture, Baylor College of Medicine, Houston, TX 77030, USA
| | - Suhas S P Rao
- The Center for Genome Architecture, Baylor College of Medicine, Houston, TX 77030, USA; Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | | | - Daniel Chauss
- Lymphocyte Nuclear Biology, NIAMS, NIH, Bethesda, MD 20892, USA
| | - Erica Sadler
- Lymphocyte Nuclear Biology, NIAMS, NIH, Bethesda, MD 20892, USA
| | - Andrea Lopez
- Lymphocyte Nuclear Biology, NIAMS, NIH, Bethesda, MD 20892, USA
| | - Marcelo A Nóbrega
- Department of Human Genetics, University of Chicago, Chicago, IL, USA
| | - Erez Lieberman Aiden
- The Center for Genome Architecture, Baylor College of Medicine, Houston, TX 77030, USA; Center for Theoretical Biological Physics, Rice University, Houston, TX 77030, USA; Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, Shanghai, China
| | - Francisco J Asturias
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical School, Aurora CO 80045, USA.
| | - Rafael Casellas
- Lymphocyte Nuclear Biology, NIAMS, NIH, Bethesda, MD 20892, USA; Center for Cancer Research, NCI, NIH, Bethesda, MD 20892, USA.
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41
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Morrish RB, Hermes M, Metz J, Stone N, Pagliara S, Chahwan R, Palombo F. Single Cell Imaging of Nuclear Architecture Changes. Front Cell Dev Biol 2019; 7:141. [PMID: 31396512 PMCID: PMC6668442 DOI: 10.3389/fcell.2019.00141] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Accepted: 07/10/2019] [Indexed: 12/31/2022] Open
Abstract
The dynamic architecture of chromatin, the macromolecular complex comprised primarily of DNA and histones, is vital for eukaryotic cell growth. Chemical and conformational changes to chromatin are important markers of functional and developmental processes in cells. However, chromatin architecture regulation has not yet been fully elucidated. Therefore, novel approaches to assessing chromatin changes at the single-cell level are required. Here we report the use of FTIR imaging and microfluidic cell-stretcher chips to assess changes to chromatin architecture and its effect on the mechanical properties of the nucleus in immune cells. FTIR imaging enables label-free chemical imaging with subcellular resolution. By optimizing the FTIR methodology and coupling it with cell segmentation analysis approach, we have identified key spectral changes corresponding to changes in DNA levels and chromatin conformation at the single cell level. By further manipulating live single cells using pressure-driven microfluidics, we found that chromatin decondensation – either during general transcriptional activation or during specific immune cell maturation – can ultimately lead to nuclear auxeticity which is a new biological phenomenon recently identified. Taken together our findings demonstrate the tight and, potentially bilateral, link between extra-cellular mechanotransduction and intra-cellular nuclear architecture.
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Affiliation(s)
- Rikke Brandstrup Morrish
- School of Physics and Astronomy, University of Exeter, Exeter, United Kingdom.,Living Systems Institute and School of Biosciences, University of Exeter, Exeter, United Kingdom
| | - Michael Hermes
- School of Physics and Astronomy, University of Exeter, Exeter, United Kingdom
| | - Jeremy Metz
- Living Systems Institute and School of Biosciences, University of Exeter, Exeter, United Kingdom
| | - Nicholas Stone
- School of Physics and Astronomy, University of Exeter, Exeter, United Kingdom
| | - Stefano Pagliara
- Living Systems Institute and School of Biosciences, University of Exeter, Exeter, United Kingdom
| | - Richard Chahwan
- Institute of Experimental Immunology, University of Zurich, Zurich, Switzerland
| | - Francesca Palombo
- School of Physics and Astronomy, University of Exeter, Exeter, United Kingdom
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42
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Tesi A, de Pretis S, Furlan M, Filipuzzi M, Morelli MJ, Andronache A, Doni M, Verrecchia A, Pelizzola M, Amati B, Sabò A. An early Myc-dependent transcriptional program orchestrates cell growth during B-cell activation. EMBO Rep 2019; 20:e47987. [PMID: 31334602 DOI: 10.15252/embr.201947987] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2019] [Revised: 06/18/2019] [Accepted: 06/27/2019] [Indexed: 12/18/2022] Open
Abstract
Upon activation, lymphocytes exit quiescence and undergo substantial increases in cell size, accompanied by activation of energy-producing and anabolic pathways, widespread chromatin decompaction, and elevated transcriptional activity. These changes depend upon prior induction of the Myc transcription factor, but how Myc controls them remains unclear. We addressed this issue by profiling the response to LPS stimulation in wild-type and c-myc-deleted primary mouse B-cells. Myc is rapidly induced, becomes detectable on virtually all active promoters and enhancers, but has no direct impact on global transcriptional activity. Instead, Myc contributes to the swift up- and down-regulation of several hundred genes, including many known regulators of the aforementioned cellular processes. Myc-activated promoters are enriched for E-box consensus motifs, bind Myc at the highest levels, and show enhanced RNA Polymerase II recruitment, the opposite being true at down-regulated loci. Remarkably, the Myc-dependent signature identified in activated B-cells is also enriched in Myc-driven B-cell lymphomas: hence, besides modulation of new cancer-specific programs, the oncogenic action of Myc may largely rely on sustained deregulation of its normal physiological targets.
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Affiliation(s)
- Alessandra Tesi
- Center for Genomic Science of IIT@SEMM, Fondazione Istituto Italiano di Tecnologia (IIT), Milan, Italy
| | - Stefano de Pretis
- Center for Genomic Science of IIT@SEMM, Fondazione Istituto Italiano di Tecnologia (IIT), Milan, Italy
| | - Mattia Furlan
- Center for Genomic Science of IIT@SEMM, Fondazione Istituto Italiano di Tecnologia (IIT), Milan, Italy
| | - Marco Filipuzzi
- Department of Experimental Oncology, European Institute of Oncology (IEO)-IRCCS, Milan, Italy
| | - Marco J Morelli
- Center for Genomic Science of IIT@SEMM, Fondazione Istituto Italiano di Tecnologia (IIT), Milan, Italy
| | - Adrian Andronache
- Center for Genomic Science of IIT@SEMM, Fondazione Istituto Italiano di Tecnologia (IIT), Milan, Italy
| | - Mirko Doni
- Department of Experimental Oncology, European Institute of Oncology (IEO)-IRCCS, Milan, Italy
| | - Alessandro Verrecchia
- Department of Experimental Oncology, European Institute of Oncology (IEO)-IRCCS, Milan, Italy
| | - Mattia Pelizzola
- Center for Genomic Science of IIT@SEMM, Fondazione Istituto Italiano di Tecnologia (IIT), Milan, Italy
| | - Bruno Amati
- Department of Experimental Oncology, European Institute of Oncology (IEO)-IRCCS, Milan, Italy
| | - Arianna Sabò
- Department of Experimental Oncology, European Institute of Oncology (IEO)-IRCCS, Milan, Italy
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43
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Barwick BG, Gupta VA, Vertino PM, Boise LH. Cell of Origin and Genetic Alterations in the Pathogenesis of Multiple Myeloma. Front Immunol 2019; 10:1121. [PMID: 31231360 PMCID: PMC6558388 DOI: 10.3389/fimmu.2019.01121] [Citation(s) in RCA: 89] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Accepted: 05/02/2019] [Indexed: 12/22/2022] Open
Abstract
B cell activation and differentiation yields plasma cells with high affinity antibodies to a given antigen in a time-frame that allows for host protection. Although the end product is most commonly humoral immunity, the rapid proliferation and somatic mutation of the B cell receptor also results in oncogenic mutations that cause B cell malignancies including plasma cell neoplasms such as multiple myeloma. Myeloma is the second most common hematological malignancy and results in over 100,000 deaths per year worldwide. The genetic alterations that occur in the germinal center, however, are not sufficient to cause myeloma, but rather impart cell proliferation potential on plasma cells, which are normally non-dividing. This pre-malignant state, referred to as monoclonal gammopathy of undetermined significance or MGUS, provides the opportunity for further genetic and epigenetic alterations eventually resulting in a progressive disease that becomes symptomatic. In this review, we will provide a brief history of clonal gammopathies and detail how some of the key discoveries were interwoven with the study of plasma cells. We will also review the genetic and epigenetic alterations discovered over the past 25 years, how these are instrumental to myeloma pathogenesis, and what these events teach us about myeloma and plasma cell biology. These data will be placed in the context of normal B cell development and differentiation and we will discuss how understanding the biology of plasma cells can lead to more effective therapies targeting multiple myeloma.
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Affiliation(s)
- Benjamin G. Barwick
- Department of Hematology and Medical Oncology, Emory University School of Medicine, Atlanta, GA, United States
- Winship Cancer Institute, Emory University, Atlanta, GA, United States
| | - Vikas A. Gupta
- Department of Hematology and Medical Oncology, Emory University School of Medicine, Atlanta, GA, United States
- Winship Cancer Institute, Emory University, Atlanta, GA, United States
| | - Paula M. Vertino
- Department of Biomedical Genetics and the Wilmot Cancer Institute, University of Rochester Medical Center, Rochester, NY, United States
| | - Lawrence H. Boise
- Department of Hematology and Medical Oncology, Emory University School of Medicine, Atlanta, GA, United States
- Winship Cancer Institute, Emory University, Atlanta, GA, United States
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44
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Baluapuri A, Hofstetter J, Dudvarski Stankovic N, Endres T, Bhandare P, Vos SM, Adhikari B, Schwarz JD, Narain A, Vogt M, Wang SY, Düster R, Jung LA, Vanselow JT, Wiegering A, Geyer M, Maric HM, Gallant P, Walz S, Schlosser A, Cramer P, Eilers M, Wolf E. MYC Recruits SPT5 to RNA Polymerase II to Promote Processive Transcription Elongation. Mol Cell 2019; 74:674-687.e11. [PMID: 30928206 PMCID: PMC6527870 DOI: 10.1016/j.molcel.2019.02.031] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Revised: 11/27/2018] [Accepted: 02/21/2019] [Indexed: 01/17/2023]
Abstract
The MYC oncoprotein binds to promoter-proximal regions of virtually all transcribed genes and enhances RNA polymerase II (Pol II) function, but its precise mode of action is poorly understood. Using mass spectrometry of both MYC and Pol II complexes, we show here that MYC controls the assembly of Pol II with a small set of transcription elongation factors that includes SPT5, a subunit of the elongation factor DSIF. MYC directly binds SPT5, recruits SPT5 to promoters, and enables the CDK7-dependent transfer of SPT5 onto Pol II. Consistent with known functions of SPT5, MYC is required for fast and processive transcription elongation. Intriguingly, the high levels of MYC that are expressed in tumors sequester SPT5 into non-functional complexes, thereby decreasing the expression of growth-suppressive genes. Altogether, these results argue that MYC controls the productive assembly of processive Pol II elongation complexes and provide insight into how oncogenic levels of MYC permit uncontrolled cellular growth. MYC enhances productive transcription by defining the protein composition of Pol II MYC directly binds SPT5 and hands it over to Pol II in a CDK7-dependent manner Transfer of SPT5 increases speed and processivity of Pol II MYC’s effects on Pol II function shape its tumor-specific gene expression profile
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Affiliation(s)
- Apoorva Baluapuri
- Cancer Systems Biology Group, Theodor Boveri Institute, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Julia Hofstetter
- Cancer Systems Biology Group, Theodor Boveri Institute, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Nevenka Dudvarski Stankovic
- Cancer Systems Biology Group, Theodor Boveri Institute, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Theresa Endres
- Department of Biochemistry and Molecular Biology, Theodor Boveri Institute, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Pranjali Bhandare
- Cancer Systems Biology Group, Theodor Boveri Institute, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Seychelle Monique Vos
- Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Bikash Adhikari
- Cancer Systems Biology Group, Theodor Boveri Institute, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Jessica Denise Schwarz
- Cancer Systems Biology Group, Theodor Boveri Institute, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Ashwin Narain
- Cancer Systems Biology Group, Theodor Boveri Institute, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Markus Vogt
- Cancer Systems Biology Group, Theodor Boveri Institute, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Shuang-Yan Wang
- Rudolf Virchow Center for Experimental Biomedicine, Josef-Schneider-Str. 2, 97080 Würzburg, Germany
| | - Robert Düster
- Institute of Structural Biology, University of Bonn, Sigmund-Freud-Str. 25, 53127 Bonn, Germany
| | - Lisa Anna Jung
- Karolinska Institutet, Department of Biosciences and Nutrition, Hälsovägen 7C, 14157 Huddinge, Sweden
| | - Jens Thorsten Vanselow
- Rudolf Virchow Center for Experimental Biomedicine, Josef-Schneider-Str. 2, 97080 Würzburg, Germany
| | - Armin Wiegering
- Department of Biochemistry and Molecular Biology, Theodor Boveri Institute, University of Würzburg, Am Hubland, 97074 Würzburg, Germany; Department of General, Visceral, Transplant, Vascular and Pediatric Surgery, University Hospital Würzburg, Josef-Schneider-Str. 2, 97080 Würzburg, Germany
| | - Matthias Geyer
- Institute of Structural Biology, University of Bonn, Sigmund-Freud-Str. 25, 53127 Bonn, Germany
| | - Hans Michael Maric
- Rudolf Virchow Center for Experimental Biomedicine, Josef-Schneider-Str. 2, 97080 Würzburg, Germany
| | - Peter Gallant
- Department of Biochemistry and Molecular Biology, Theodor Boveri Institute, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Susanne Walz
- Core Unit Bioinformatics, Comprehensive Cancer Center Mainfranken, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Andreas Schlosser
- Rudolf Virchow Center for Experimental Biomedicine, Josef-Schneider-Str. 2, 97080 Würzburg, Germany
| | - Patrick Cramer
- Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany; Karolinska Institutet, Department of Biosciences and Nutrition, Hälsovägen 7C, 14157 Huddinge, Sweden
| | - Martin Eilers
- Department of Biochemistry and Molecular Biology, Theodor Boveri Institute, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Elmar Wolf
- Cancer Systems Biology Group, Theodor Boveri Institute, University of Würzburg, Am Hubland, 97074 Würzburg, Germany.
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45
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Stretton C, Lipina C, Hyde R, Cwiklinski E, Hoffmann TM, Taylor PM, Hundal HS. CDK7 is a component of the integrated stress response regulating SNAT2 (SLC38A2)/System A adaptation in response to cellular amino acid deprivation. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2019; 1866:978-991. [PMID: 30857869 PMCID: PMC6456927 DOI: 10.1016/j.bbamcr.2019.03.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Revised: 03/04/2019] [Accepted: 03/06/2019] [Indexed: 12/31/2022]
Abstract
Extracellular amino acid (AA) withdrawal/restriction invokes an integrated stress response (ISR) that induces global suppression of protein synthesis whilst allowing transcription and translation of a select group of genes, whose protein products facilitate cellular adaptation to AA insufficiency. Transcriptional induction of the System A/SNAT2 AA transporter represents a classic adaptation response and crucially depends upon activation of the General Control Nonderepressible-2 kinase/Activating transcription factor 4 (GCN2/ATF4) pathway. However, the ISR may also include additional signalling inputs operating in conjunction or independently of GCN2/ATF4 to upregulate SNAT2. Herein, we show that whilst pharmacological inhibition of MEK-ERK, mTORC1 and p38 MAP kinase signalling has no detectable effect on System A upregulation, inhibitors targeting GSK3 (e.g. SB415286) caused significant repression of the SNAT2 adaptation response. Strikingly, the effects of SB415286 persist in cells in which GSK3α/β have been stably silenced indicating an off-target effect. We show that SB415286 can also inhibit cyclin-dependent kinases (CDK) and that roscovitine and flavopiridol (two pan CDK inhibitors) are effective repressors of the SNAT2 adaptive response. In particular, our work reveals that CDK7 activity is upregulated in AA-deprived cells in a GCN-2-dependent manner and that a potent and selective CDK7 inhibitor, THZ-1, not only attenuates the increase in ATF4 expression but blocks System A adaptation. Importantly, the inhibitory effects of THZ-1 on System A adaptation are mitigated in cells expressing a doxycycline-inducible drug-resistant form of CDK7. Our data identify CDK7 as a novel component of the ISR regulating System A adaptation in response to AA insufficiency. Roscovitine and flavopiridol (CDK inhibitors) block the System A adaptive response. Extracellular amino acid (AA) withdrawal induces CDK7 activation. Pharmacological inhibition of GCN2 represses CDK7 activation in AA-deprived cells. Targeted suppression of CDK7 represses ATF4 expression and System A adaptation.
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Affiliation(s)
- Clare Stretton
- Division of Cell Signalling and Immunology, Sir James Black Centre, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Christopher Lipina
- Division of Cell Signalling and Immunology, Sir James Black Centre, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Russell Hyde
- Division of Cell Signalling and Immunology, Sir James Black Centre, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Emma Cwiklinski
- Division of Cell Signalling and Immunology, Sir James Black Centre, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Thorsten M Hoffmann
- Division of Cell Signalling and Immunology, Sir James Black Centre, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Peter M Taylor
- Division of Cell Signalling and Immunology, Sir James Black Centre, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Harinder S Hundal
- Division of Cell Signalling and Immunology, Sir James Black Centre, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK.
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46
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Abstract
Animal and plant centromeres are embedded in repetitive "satellite" DNA, but are thought to be epigenetically specified. To define genetic characteristics of centromeres, we surveyed satellite DNA from diverse eukaryotes and identified variation in <10-bp dyad symmetries predicted to adopt non-B-form conformations. Organisms lacking centromeric dyad symmetries had binding sites for sequence-specific DNA-binding proteins with DNA-bending activity. For example, human and mouse centromeres are depleted for dyad symmetries, but are enriched for non-B-form DNA and are associated with binding sites for the conserved DNA-binding protein CENP-B, which is required for artificial centromere function but is paradoxically nonessential. We also detected dyad symmetries and predicted non-B-form DNA structures at neocentromeres, which form at ectopic loci. We propose that centromeres form at non-B-form DNA because of dyad symmetries or are strengthened by sequence-specific DNA binding proteins. This may resolve the CENP-B paradox and provide a general basis for centromere specification.
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Affiliation(s)
- Sivakanthan Kasinathan
- Medical Scientist Training Program, University of Washington School of Medicine, Seattle, WA.,Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA
| | - Steven Henikoff
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA.,Howard Hughes Medical Institute, Seattle, WA
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Structures of an RNA polymerase promoter melting intermediate elucidate DNA unwinding. Nature 2019; 565:382-385. [PMID: 30626968 DOI: 10.1038/s41586-018-0840-5] [Citation(s) in RCA: 71] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Accepted: 11/28/2018] [Indexed: 01/25/2023]
Abstract
A key regulated step of transcription is promoter melting by RNA polymerase (RNAP) to form the open promoter complex1-3. To generate the open complex, the conserved catalytic core of the RNAP combines with initiation factors to locate promoter DNA, unwind 12-14 base pairs of the DNA duplex and load the template-strand DNA into the RNAP active site. Formation of the open complex is a multi-step process during which transient intermediates of unknown structure are formed4-6. Here we present cryo-electron microscopy structures of bacterial RNAP-promoter DNA complexes, including structures of partially melted intermediates. The structures show that late steps of promoter melting occur within the RNAP cleft, delineate key roles for fork-loop 2 and switch 2-universal structural features of RNAP-in restricting access of DNA to the RNAP active site, and explain why clamp opening is required to allow entry of single-stranded template DNA into the active site. The key roles of fork-loop 2 and switch 2 suggest a common mechanism for late steps in promoter DNA opening to enable gene expression across all domains of life.
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48
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PRMT5 is essential for B cell development and germinal center dynamics. Nat Commun 2019; 10:22. [PMID: 30604754 PMCID: PMC6318318 DOI: 10.1038/s41467-018-07884-6] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Accepted: 12/04/2018] [Indexed: 01/05/2023] Open
Abstract
Mechanisms regulating B cell development, activation, education in the germinal center (GC) and differentiation, underpin the humoral immune response. Protein arginine methyltransferase 5 (Prmt5), which catalyzes most symmetric dimethyl arginine protein modifications, is overexpressed in B cell lymphomas but its function in normal B cells is poorly defined. Here we show that Prmt5 is necessary for antibody responses and has essential but distinct functions in all proliferative B cell stages in mice. Prmt5 is necessary for B cell development by preventing p53-dependent and p53-independent blocks in Pro-B and Pre-B cells, respectively. By contrast, Prmt5 protects, via p53-independent pathways, mature B cells from apoptosis during activation, promotes GC expansion, and counters plasma cell differentiation. Phenotypic and RNA-seq data indicate that Prmt5 regulates GC light zone B cell fate by regulating transcriptional programs, achieved in part by ensuring RNA splicing fidelity. Our results establish Prmt5 as an essential regulator of B cell biology. Protective antibody responses depend critically on proper B cell development and differentiation at multiple stages. Here the authors show that a protein arginine methyltransferase, Prmt5 uses multiples pathways to prevent death of immature B cells, yet modulates, in p53-independent manners, the survival and differentiation of mature B cells.
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Erickson B, Sheridan RM, Cortazar M, Bentley DL. Dynamic turnover of paused Pol II complexes at human promoters. Genes Dev 2018; 32:1215-1225. [PMID: 30150253 PMCID: PMC6120720 DOI: 10.1101/gad.316810.118] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Accepted: 07/11/2018] [Indexed: 12/30/2022]
Abstract
Paused RNA polymerase II (Pol II) that piles up near most human promoters is the target of mechanisms that control entry into productive elongation. Whether paused Pol II is a stable or dynamic target remains unresolved. We report that most 5' paused Pol II throughout the genome is turned over within 2 min. This process is revealed under hypertonic conditions that prevent Pol II recruitment to promoters. This turnover requires cell viability but is not prevented by inhibiting transcription elongation, suggesting that it is mediated at the level of termination. When initiation was prevented by triptolide during recovery from high salt, a novel preinitiated state of Pol II lacking the pausing factor Spt5 accumulated at transcription start sites. We propose that Pol II occupancy near 5' ends is governed by a cycle of ongoing assembly of preinitiated complexes that transition to pause sites followed by eviction from the DNA template. This model suggests that mechanisms regulating the transition to productive elongation at pause sites operate on a dynamic population of Pol II that is turning over at rates far higher than previously suspected. We suggest that a plausible alternative to elongation control via escape from a stable pause is by escape from premature termination.
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Affiliation(s)
- Benjamin Erickson
- Department of Biochemistry and Molecular Genetics, RNA Bioscience Initiative, University of Colorado School of Medicine, Aurora, Colorado 80045, USA
| | - Ryan M Sheridan
- Department of Biochemistry and Molecular Genetics, RNA Bioscience Initiative, University of Colorado School of Medicine, Aurora, Colorado 80045, USA
| | - Michael Cortazar
- Department of Biochemistry and Molecular Genetics, RNA Bioscience Initiative, University of Colorado School of Medicine, Aurora, Colorado 80045, USA
| | - David L Bentley
- Department of Biochemistry and Molecular Genetics, RNA Bioscience Initiative, University of Colorado School of Medicine, Aurora, Colorado 80045, USA
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50
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Talbert PB, Henikoff S. Transcribing Centromeres: Noncoding RNAs and Kinetochore Assembly. Trends Genet 2018; 34:587-599. [DOI: 10.1016/j.tig.2018.05.001] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Revised: 05/08/2018] [Accepted: 05/09/2018] [Indexed: 12/20/2022]
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