1
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Bai G, Endres T, Kühbacher U, Greer BH, Peacock EM, Crossley MP, Sathirachinda A, Cortez D, Eichman BF, Cimprich KA. HLTF Prevents G4 Accumulation and Promotes G4-induced Fork Slowing to Maintain Genome Stability. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.27.563641. [PMID: 37961428 PMCID: PMC10634870 DOI: 10.1101/2023.10.27.563641] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
G-quadruplexes (G4s) form throughout the genome and influence important cellular processes, but their deregulation can challenge DNA replication fork progression and threaten genome stability. Here, we demonstrate an unexpected, dual role for the dsDNA translocase HLTF in G4 metabolism. First, we find that HLTF is enriched at G4s in the human genome and suppresses G4 accumulation throughout the cell cycle using its ATPase activity. This function of HLTF affects telomere maintenance by restricting alternative lengthening of telomeres, a process stimulated by G4s. We also show that HLTF and MSH2, a mismatch repair factor that binds G4s, act in independent pathways to suppress G4s and to promote resistance to G4 stabilization. In a second, distinct role, HLTF restrains DNA synthesis upon G4 stabilization by suppressing PrimPol-dependent repriming. Together, the dual functions of HLTF in the G4 response prevent DNA damage and potentially mutagenic replication to safeguard genome stability.
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2
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Role of Histone Tails and Single Strand DNA Breaks in Nucleosomal Arrest of RNA Polymerase. Int J Mol Sci 2023; 24:ijms24032295. [PMID: 36768621 PMCID: PMC9917218 DOI: 10.3390/ijms24032295] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2022] [Revised: 01/13/2023] [Accepted: 01/19/2023] [Indexed: 01/26/2023] Open
Abstract
Transcription through nucleosomes by RNA polymerases (RNAP) is accompanied by formation of small intranucleosomal DNA loops (i-loops). The i-loops form more efficiently in the presence of single-strand breaks or gaps in a non-template DNA strand (NT-SSBs) and induce arrest of transcribing RNAP, thus allowing detection of NT-SSBs by the enzyme. Here we examined the role of histone tails and extranucleosomal NT-SSBs in i-loop formation and arrest of RNAP during transcription of promoter-proximal region of nucleosomal DNA. NT-SSBs present in linker DNA induce arrest of RNAP +1 to +15 bp in the nucleosome, suggesting formation of the i-loops; the arrest is more efficient in the presence of the histone tails. Consistently, DNA footprinting reveals formation of an i-loop after stalling RNAP at the position +2 and backtracking to position +1. The data suggest that histone tails and NT-SSBs present in linker DNA strongly facilitate formation of the i-loops during transcription through the promoter-proximal region of nucleosomal DNA.
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3
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Roles of G4-DNA and G4-RNA in Class Switch Recombination and Additional Regulations in B-Lymphocytes. Molecules 2023; 28:molecules28031159. [PMID: 36770824 PMCID: PMC9921937 DOI: 10.3390/molecules28031159] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Revised: 01/18/2023] [Accepted: 01/19/2023] [Indexed: 01/26/2023] Open
Abstract
Mature B cells notably diversify immunoglobulin (Ig) production through class switch recombination (CSR), allowing the junction of distant "switch" (S) regions. CSR is initiated by activation-induced deaminase (AID), which targets cytosines adequately exposed within single-stranded DNA of transcribed targeted S regions, with a specific affinity for WRCY motifs. In mammals, G-rich sequences are additionally present in S regions, forming canonical G-quadruplexes (G4s) DNA structures, which favor CSR. Small molecules interacting with G4-DNA (G4 ligands), proved able to regulate CSR in B lymphocytes, either positively (such as for nucleoside diphosphate kinase isoforms) or negatively (such as for RHPS4). G4-DNA is also implicated in the control of transcription, and due to their impact on both CSR and transcriptional regulation, G4-rich sequences likely play a role in the natural history of B cell malignancies. Since G4-DNA stands at multiple locations in the genome, notably within oncogene promoters, it remains to be clarified how it can more specifically promote legitimate CSR in physiology, rather than pathogenic translocation. The specific regulatory role of G4 structures in transcribed DNA and/or in corresponding transcripts and recombination hereby appears as a major issue for understanding immune responses and lymphomagenesis.
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Ye M, Chen EV, Pfeil SH, Martin KN, Atrafi T, Yun S, Martinez Z, Yatsunyk LA. Homopurine guanine-rich sequences in complex with N-methyl mesoporphyrin IX form parallel G-quadruplex dimers and display a unique symmetry tetrad. Bioorg Med Chem 2023; 77:117112. [PMID: 36508994 PMCID: PMC9812923 DOI: 10.1016/j.bmc.2022.117112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Revised: 11/24/2022] [Accepted: 11/28/2022] [Indexed: 12/03/2022]
Abstract
DNA can fold into G-quadruplexes (GQs), non-canonical secondary structures formed by π-π stacking of G-tetrads. GQs are important in many biological processes, which makes them promising therapeutic targets. We identified a 42-nucleotide long, purine-only G-rich sequence from human genome, which contains eight G-stretches connected by A and AAAA loops. We divided this sequence into five unique segments, four guanine stretches each, named GA1-5. In order to investigate the role of adenines in GQ structure formation, we performed biophysical and X-ray crystallographic studies of GA1-5 and their complexes with a highly selective GQ ligand, N-methyl mesoporphyrin IX (NMM). Our data indicate that all variants form parallel GQs whose stability depends on the number of flexible AAAA loops. GA1-3 bind NMM with 1:1 stoichiometry. The Ka for GA1 and GA3 is modest, ∼0.3 μM -1, and that for GA2 is significantly higher, ∼1.2 μM -1. NMM stabilizes GA1-3 by 14.6, 13.1, and 7.0 °C, respectively, at 2 equivalents. We determined X-ray crystal structures of GA1-NMM (1.98 Å resolution) and GA3-NMM (2.01 Å). The structures confirm the parallel topology of GQs with all adenines forming loops and display NMM binding at the 3' G-tetrad. Both complexes dimerize through the 5' interface. We observe two novel structural features: 1) a 'symmetry tetrad' at the dimer interface, which is formed by two guanines from each GQ monomer and 2) a NMM dimer in GA1-NMM. Our structural work confirms great flexibility of adenines as structural elements in GQ formation and contributes greatly to our understanding of the structural diversity of GQs and their modes of interaction with small molecule ligands.
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Affiliation(s)
- Ming Ye
- Department of Chemistry and Biochemistry, Swarthmore College, Swarthmore, PA 19081, United States
| | - Erin V Chen
- Department of Chemistry and Biochemistry, Swarthmore College, Swarthmore, PA 19081, United States
| | - Shawn H Pfeil
- Department of Physics, West Chester University, West Chester, PA 19383, United States
| | - Kailey N Martin
- Department of Chemistry and Biochemistry, Swarthmore College, Swarthmore, PA 19081, United States
| | - Tamanaa Atrafi
- Department of Chemistry and Biochemistry, Swarthmore College, Swarthmore, PA 19081, United States
| | - Sara Yun
- Department of Chemistry and Biochemistry, Swarthmore College, Swarthmore, PA 19081, United States
| | - Zahara Martinez
- Department of Chemistry and Biochemistry, Swarthmore College, Swarthmore, PA 19081, United States
| | - Liliya A Yatsunyk
- Department of Chemistry and Biochemistry, Swarthmore College, Swarthmore, PA 19081, United States.
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5
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Masnovo C, Lobo AF, Mirkin SM. Replication dependent and independent mechanisms of GAA repeat instability. DNA Repair (Amst) 2022; 118:103385. [PMID: 35952488 PMCID: PMC9675320 DOI: 10.1016/j.dnarep.2022.103385] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Revised: 07/28/2022] [Accepted: 07/30/2022] [Indexed: 11/20/2022]
Abstract
Trinucleotide repeat instability is a driver of human disease. Large expansions of (GAA)n repeats in the first intron of the FXN gene are the cause Friedreich's ataxia (FRDA), a progressive degenerative disorder which cannot yet be prevented or treated. (GAA)n repeat instability arises during both replication-dependent processes, such as cell division and intergenerational transmission, as well as in terminally differentiated somatic tissues. Here, we provide a brief historical overview on the discovery of (GAA)n repeat expansions and their association to FRDA, followed by recent advances in the identification of triplex H-DNA formation and replication fork stalling. The main body of this review focuses on the last decade of progress in understanding the mechanism of (GAA)n repeat instability during DNA replication and/or DNA repair. We propose that the discovery of additional mechanisms of (GAA)n repeat instability can be achieved via both comparative approaches to other repeat expansion diseases and genome-wide association studies. Finally, we discuss the advances towards FRDA prevention or amelioration that specifically target (GAA)n repeat expansions.
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Affiliation(s)
- Chiara Masnovo
- Department of Biology, Tufts University, Medford, MA 02155, USA
| | - Ayesha F Lobo
- Department of Biology, Tufts University, Medford, MA 02155, USA
| | - Sergei M Mirkin
- Department of Biology, Tufts University, Medford, MA 02155, USA.
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6
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Belotserkovskii BP, Hanawalt PC. Topology and kinetics of R-loop formation. Biophys J 2022; 121:3345-3357. [PMID: 36004778 PMCID: PMC9515371 DOI: 10.1016/j.bpj.2022.08.026] [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: 04/11/2022] [Revised: 07/06/2022] [Accepted: 08/18/2022] [Indexed: 11/19/2022] Open
Abstract
R-loops are structures containing an RNA-DNA duplex and an unpaired DNA strand. They can be formed upon "invasion" of an RNA strand into a DNA duplex, during which the RNA displaces the homologous DNA strand and binds the complementary strand. R-loops have many significant beneficial or deleterious biological effects, so it is important to understand the mechanisms for their generation and processing. We propose a model for co-transcriptional R-loop formation, in which their generation requires passage of the nascent RNA "tail" through the gap between the separated DNA strands. This passage becomes increasingly difficult with lengthening of the RNA tail. The length of the tail increases upon increasing distance between the transcription start site and the site of R-loop initiation. This causes reduced yields of R-loops with greater distance from the transcription start site. However, alternative pathways for R-loop formation are possible, involving either transient disruption of the transcription complex or the hypothetical formation of a triple-stranded structure, as a "collapsed R-loop." These alternative pathways could account for the fact that in many systems R-loops are observed very far from the transcription start site. Our model is consistent with experimental data and makes general predictions about the kinetics of R-loop formation.
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7
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Yousuf A, Ahmed N, Qurashi A. Non-canonical DNA/RNA structures associated with the pathogenesis of Fragile X-associated tremor/ataxia syndrome and Fragile X syndrome. Front Genet 2022; 13:866021. [PMID: 36110216 PMCID: PMC9468596 DOI: 10.3389/fgene.2022.866021] [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: 01/30/2022] [Accepted: 07/22/2022] [Indexed: 11/13/2022] Open
Abstract
Fragile X-associated tremor/ataxia syndrome (FXTAS) and fragile X syndrome (FXS) are primary examples of fragile X-related disorders (FXDs) caused by abnormal expansion of CGG repeats above a certain threshold in the 5′-untranslated region of the fragile X mental retardation (FMR1) gene. Both diseases have distinct clinical manifestations and molecular pathogenesis. FXTAS is a late-adult-onset neurodegenerative disorder caused by a premutation (PM) allele (CGG expansion of 55–200 repeats), resulting in FMR1 gene hyperexpression. On the other hand, FXS is a neurodevelopmental disorder that results from a full mutation (FM) allele (CGG expansions of ≥200 repeats) leading to heterochromatization and transcriptional silencing of the FMR1 gene. The main challenge is to determine how CGG repeat expansion affects the fundamentally distinct nature of FMR1 expression in FM and PM ranges. Abnormal CGG repeat expansions form a variety of non-canonical DNA and RNA structures that can disrupt various cellular processes and cause distinct effects in PM and FM alleles. Here, we review these structures and how they are related to underlying mutations and disease pathology in FXS and FXTAS. Finally, as new CGG expansions within the genome have been identified, it will be interesting to determine their implications in disease pathology and treatment.
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8
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Structure of an Intranucleosomal DNA Loop That Senses DNA Damage during Transcription. Cells 2022; 11:cells11172678. [PMID: 36078089 PMCID: PMC9454427 DOI: 10.3390/cells11172678] [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: 07/29/2022] [Revised: 08/22/2022] [Accepted: 08/24/2022] [Indexed: 11/16/2022] Open
Abstract
Transcription through chromatin by RNA polymerase II (Pol II) is accompanied by the formation of small intranucleosomal DNA loops containing the enzyme (i-loops) that are involved in survival of core histones on the DNA and arrest of Pol II during the transcription of damaged DNA. However, the structures of i-loops have not been determined. Here, the structures of the intermediates formed during transcription through a nucleosome containing intact or damaged DNA were studied using biochemical approaches and electron microscopy. After RNA polymerase reaches position +24 from the nucleosomal boundary, the enzyme can backtrack to position +20, where DNA behind the enzyme recoils on the surface of the histone octamer, forming an i-loop that locks Pol II in the arrested state. Since the i-loop is formed more efficiently in the presence of SSBs positioned behind the transcribing enzyme, the loop could play a role in the transcription-coupled repair of DNA damage hidden in the chromatin structure.
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High-throughput techniques enable advances in the roles of DNA and RNA secondary structures in transcriptional and post-transcriptional gene regulation. Genome Biol 2022; 23:159. [PMID: 35851062 PMCID: PMC9290270 DOI: 10.1186/s13059-022-02727-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Accepted: 07/07/2022] [Indexed: 12/27/2022] Open
Abstract
The most stable structure of DNA is the canonical right-handed double helix termed B DNA. However, certain environments and sequence motifs favor alternative conformations, termed non-canonical secondary structures. The roles of DNA and RNA secondary structures in transcriptional regulation remain incompletely understood. However, advances in high-throughput assays have enabled genome wide characterization of some secondary structures. Here, we describe their regulatory functions in promoters and 3’UTRs, providing insights into key mechanisms through which they regulate gene expression. We discuss their implication in human disease, and how advances in molecular technologies and emerging high-throughput experimental methods could provide additional insights.
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Mechanism for R-loop formation remote from the transcription start site: Topological issues and possible facilitation by dissociation of RNA polymerase. DNA Repair (Amst) 2022; 110:103275. [DOI: 10.1016/j.dnarep.2022.103275] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2021] [Revised: 01/13/2022] [Accepted: 01/17/2022] [Indexed: 11/18/2022]
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11
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Teng FY, Jiang ZZ, Guo M, Tan XZ, Chen F, Xi XG, Xu Y. G-quadruplex DNA: a novel target for drug design. Cell Mol Life Sci 2021; 78:6557-6583. [PMID: 34459951 PMCID: PMC11072987 DOI: 10.1007/s00018-021-03921-8] [Citation(s) in RCA: 50] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Revised: 07/13/2021] [Accepted: 08/12/2021] [Indexed: 02/08/2023]
Abstract
G-quadruplex (G4) DNA is a type of quadruple helix structure formed by a continuous guanine-rich DNA sequence. Emerging evidence in recent years authenticated that G4 DNA structures exist both in cell-free and cellular systems, and function in different diseases, especially in various cancers, aging, neurological diseases, and have been considered novel promising targets for drug design. In this review, we summarize the detection method and the structure of G4, highlighting some non-canonical G4 DNA structures, such as G4 with a bulge, a vacancy, or a hairpin. Subsequently, the functions of G4 DNA in physiological processes are discussed, especially their regulation of DNA replication, transcription of disease-related genes (c-MYC, BCL-2, KRAS, c-KIT et al.), telomere maintenance, and epigenetic regulation. Typical G4 ligands that target promoters and telomeres for drug design are also reviewed, including ellipticine derivatives, quinoxaline analogs, telomestatin analogs, berberine derivatives, and CX-5461, which is currently in advanced phase I/II clinical trials for patients with hematologic cancer and BRCA1/2-deficient tumors. Furthermore, since the long-term stable existence of G4 DNA structures could result in genomic instability, we summarized the G4 unfolding mechanisms emerged recently by multiple G4-specific DNA helicases, such as Pif1, RecQ family helicases, FANCJ, and DHX36. This review aims to present a general overview of the field of G-quadruplex DNA that has progressed in recent years and provides potential strategies for drug design and disease treatment.
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Affiliation(s)
- Fang-Yuan Teng
- Experimental Medicine Center, The Affiliated Hospital of Southwest Medical University, Luzhou, 646000, Sichuan, China
- Department of Endocrinology and Metabolism, The Affiliated Hospital of Southwest Medical University, Luzhou, 646000, Sichuan, China
- Cardiovascular and Metabolic Diseases Key Laboratory of Luzhou, and Sichuan Clinical Research Center for Nephropathy, and Academician (Expert) Workstation of Sichuan Province, The Affiliated Hospital of Southwest Medical University, Luzhou, 646000, Sichuan, China
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, 712100, Shaanxi, China
| | - Zong-Zhe Jiang
- Experimental Medicine Center, The Affiliated Hospital of Southwest Medical University, Luzhou, 646000, Sichuan, China
- Department of Endocrinology and Metabolism, The Affiliated Hospital of Southwest Medical University, Luzhou, 646000, Sichuan, China
- Cardiovascular and Metabolic Diseases Key Laboratory of Luzhou, and Sichuan Clinical Research Center for Nephropathy, and Academician (Expert) Workstation of Sichuan Province, The Affiliated Hospital of Southwest Medical University, Luzhou, 646000, Sichuan, China
| | - Man Guo
- Department of Endocrinology and Metabolism, The Affiliated Hospital of Southwest Medical University, Luzhou, 646000, Sichuan, China
- Cardiovascular and Metabolic Diseases Key Laboratory of Luzhou, and Sichuan Clinical Research Center for Nephropathy, and Academician (Expert) Workstation of Sichuan Province, The Affiliated Hospital of Southwest Medical University, Luzhou, 646000, Sichuan, China
| | - Xiao-Zhen Tan
- Experimental Medicine Center, The Affiliated Hospital of Southwest Medical University, Luzhou, 646000, Sichuan, China
- Department of Endocrinology and Metabolism, The Affiliated Hospital of Southwest Medical University, Luzhou, 646000, Sichuan, China
- Cardiovascular and Metabolic Diseases Key Laboratory of Luzhou, and Sichuan Clinical Research Center for Nephropathy, and Academician (Expert) Workstation of Sichuan Province, The Affiliated Hospital of Southwest Medical University, Luzhou, 646000, Sichuan, China
| | - Feng Chen
- Experimental Medicine Center, The Affiliated Hospital of Southwest Medical University, Luzhou, 646000, Sichuan, China
| | - Xu-Guang Xi
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, 712100, Shaanxi, China.
- LBPA, Ecole Normale Supérieure Paris-Saclay, CNRS, Université Paris Saclay, 61, Avenue du Président Wilson, 94235, Cachan, France.
| | - Yong Xu
- Experimental Medicine Center, The Affiliated Hospital of Southwest Medical University, Luzhou, 646000, Sichuan, China.
- Department of Endocrinology and Metabolism, The Affiliated Hospital of Southwest Medical University, Luzhou, 646000, Sichuan, China.
- Cardiovascular and Metabolic Diseases Key Laboratory of Luzhou, and Sichuan Clinical Research Center for Nephropathy, and Academician (Expert) Workstation of Sichuan Province, The Affiliated Hospital of Southwest Medical University, Luzhou, 646000, Sichuan, China.
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12
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Consistent Assignment of Risk and Benign Allele at rs2303153 in the CF Modifier Gene SCNN1B in Three Independent F508del- CFTR Homozygous Patient Populations. Genes (Basel) 2021; 12:genes12101554. [PMID: 34680949 PMCID: PMC8535344 DOI: 10.3390/genes12101554] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Revised: 09/27/2021] [Accepted: 09/28/2021] [Indexed: 11/17/2022] Open
Abstract
CFTR encodes for a chloride and bicarbonate channel expressed at the apical membrane of polarized epithelial cells. Transepithelial sodium transport mediated by the amiloride-sensitive sodium channel ENaC is thought to contribute to the manifestation of CF disease. Thus, ENaC is a therapeutic target in CF and a valid cystic fibrosis modifier gene. We have characterized SCNN1B as a genetic modifier in the three independent patient cohorts of F508del-CFTR homozygotes. We could identify a regulatory element at SCNN1B to the genomic segment rs168748-rs2303153-rs4968000 by fine-mapping (Pbest = 0.0177), consistently observing the risk allele rs2303153-C and the contrasting benign allele rs2303153-G in all three patient cohorts. Furthermore, our results show that expression levels of SCNN1B are associated with rs2303153 genotype in intestinal epithelia (p = 0.003). Our data confirm that the well-established biological role of SCNN1B can be recognized by an association study on informative endophenotypes in the rare disease cystic fibrosis and calls attention to reproducible results in association studies obtained from small, albeit carefully characterized patient populations.
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Transcription Inhibition by PNA-Induced R-Loops. Methods Mol Biol 2021; 2105:141-155. [PMID: 32088868 DOI: 10.1007/978-1-0716-0243-0_8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
R-loops are structures consisting of an RNA-DNA duplex and an unpaired DNA strand. They can form during transcription upon nascent RNA "threadback" invasion into the DNA duplex to displace the non-template DNA strand. R-loops occur naturally in all kingdoms of life, and they have multiple biological effects. Therefore, it is of interest to study the artificial induction of R-loops and to monitor their effects in model in vitro systems to learn mechanisms. Here we describe transcription blockage in vitro by R-loop formation induced by peptide nucleic acid (PNA) binding to the non-template DNA strand.
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Oh J, Xu J, Chong J, Wang D. Molecular basis of transcriptional pausing, stalling, and transcription-coupled repair initiation. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2020; 1864:194659. [PMID: 33271312 DOI: 10.1016/j.bbagrm.2020.194659] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Revised: 11/21/2020] [Accepted: 11/23/2020] [Indexed: 12/24/2022]
Abstract
Transcription elongation by RNA polymerase II (Pol II) is constantly challenged by numerous types of obstacles that lead to transcriptional pausing or stalling. These obstacles include DNA lesions, DNA epigenetic modifications, DNA binding proteins, and non-B form DNA structures. In particular, lesion-induced prolonged transcriptional blockage or stalling leads to genome instability, cellular dysfunction, and cell death. Transcription-coupled nucleotide excision repair (TC-NER) pathway is the first line of defense that detects and repairs these transcription-blocking DNA lesions. In this review, we will first summarize the recent research progress toward understanding the molecular basis of transcriptional pausing and stalling by different kinds of obstacles. We will then discuss new insights into Pol II-mediated lesion recognition and the roles of CSB in TC-NER.
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Affiliation(s)
- Juntaek Oh
- Division of Pharmaceutical Sciences, Skaggs School of Pharmacy & Pharmaceutical Sciences; University of California, San Diego, La Jolla, CA 92093, United States
| | - Jun Xu
- Division of Pharmaceutical Sciences, Skaggs School of Pharmacy & Pharmaceutical Sciences; University of California, San Diego, La Jolla, CA 92093, United States
| | - Jenny Chong
- Division of Pharmaceutical Sciences, Skaggs School of Pharmacy & Pharmaceutical Sciences; University of California, San Diego, La Jolla, CA 92093, United States
| | - Dong Wang
- Division of Pharmaceutical Sciences, Skaggs School of Pharmacy & Pharmaceutical Sciences; University of California, San Diego, La Jolla, CA 92093, United States; Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093, United States; Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093, United States.
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Current understanding of CREPT and p15RS, carboxy-terminal domain (CTD)-interacting proteins, in human cancers. Oncogene 2020; 40:705-716. [PMID: 33239754 DOI: 10.1038/s41388-020-01544-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Revised: 10/21/2020] [Accepted: 10/28/2020] [Indexed: 12/27/2022]
Abstract
CREPT and p15RS, also named RPRD1B and RPRD1A, are RPRD (regulation of nuclear pre-mRNA-domain-containing) proteins containing C-terminal domain (CTD)-interacting domain (CID), which mediates the binding to the CTD of Rpb1, the largest subunit of RNA polymerase II (RNAPII). CREPT and p15RS are highly conserved, with a common yeast orthologue Rtt103. Intriguingly, human CREPT and p15RS possess opposite functions in the regulation of cell proliferation and tumorigenesis. While p15RS inhibits cell proliferation, CREPT promotes cell cycle and tumor growth. Aberrant expression of both CREPT and p15RS was found in numerous types of cancers. At the molecular level, both CREPT and p15RS were reported to regulate gene transcription by interacting with RNAPII. However, CREPT also exerts a key function in the processes linked to DNA damage repairs. In this review, we summarized the recent studies regarding the biological roles of CREPT and p15RS, as well as the molecular mechanisms underlying their activities. Fully revealing the mechanisms of CREPT and p15RS functions will not only provide new insights into understanding gene transcription and maintenance of DNA stability in tumors, but also promote new approach development for tumor diagnosis and therapy.
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16
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Vågbø CB, Slupphaug G. RNA in DNA repair. DNA Repair (Amst) 2020; 95:102927. [DOI: 10.1016/j.dnarep.2020.102927] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 07/07/2020] [Accepted: 07/08/2020] [Indexed: 12/22/2022]
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17
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R-loop induced G-quadruplex in non-template promotes transcription by successive R-loop formation. Nat Commun 2020; 11:3392. [PMID: 32636376 PMCID: PMC7341879 DOI: 10.1038/s41467-020-17176-7] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Accepted: 06/17/2020] [Indexed: 01/06/2023] Open
Abstract
G-quadruplex (G4) is a noncanonical secondary structure of DNA or RNA which can enhance or repress gene expression, yet the underlying molecular mechanism remains uncertain. Here we show that when positioned downstream of transcription start site, the orientation of potential G4 forming sequence (PQS), but not the sequence alters transcriptional output. Ensemble in vitro transcription assays indicate that PQS in the non-template increases mRNA production rate and yield. Using sequential single molecule detection stages, we demonstrate that while binding and initiation of T7 RNA polymerase is unchanged, the efficiency of elongation and the final mRNA output is higher when PQS is in the non-template. Strikingly, the enhanced elongation arises from the transcription-induced R-loop formation, which in turn generates G4 structure in the non-template. The G4 stabilized R-loop leads to increased transcription by a mechanism involving successive rounds of R-loop formation. G-quadruplex (G4) forming sequences are highly enriched in the human genome and function as important regulators of diverse range of biological processes. Here the authors show that while G4 structures on template strand block transcription, folding on the non-template strand enhances transcription by means of successive R-loop formation.
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Subramanian H, Gatenby RA. Evolutionary advantage of anti-parallel strand orientation of duplex DNA. Sci Rep 2020; 10:9883. [PMID: 32555277 PMCID: PMC7303137 DOI: 10.1038/s41598-020-66705-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2020] [Accepted: 05/22/2020] [Indexed: 11/09/2022] Open
Abstract
DNA in all living systems shares common properties that are remarkably well suited to its function, suggesting refinement by evolution. However, DNA also shares some counter-intuitive properties which confer no obvious benefit, such as strand directionality and anti-parallel strand orientation, which together result in the complicated lagging strand replication. The evolutionary dynamics that led to these properties of DNA remain unknown but their universality suggests that they confer as yet unknown selective advantage to DNA. In this article, we identify an evolutionary advantage of anti-parallel strand orientation of duplex DNA, within a given set of plausible premises. The advantage stems from the increased rate of replication, achieved by dividing the DNA into predictable, independently and simultaneously replicating segments, as opposed to sequentially replicating the entire DNA, thereby parallelizing the replication process. We show that anti-parallel strand orientation is essential for such a replicative organization of DNA, given our premises, the most important of which is the assumption of the presence of sequence-dependent asymmetric cooperativity in DNA.
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Affiliation(s)
| | - Robert A Gatenby
- Integrated Mathematical Oncology Department, Cancer Biology and Evolution Program, H. Lee Moffitt Cancer Center and Research Institute, 12902, USF Magnolia Dr, Tampa, Florida, USA
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19
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Kim N. The Interplay between G-quadruplex and Transcription. Curr Med Chem 2019; 26:2898-2917. [PMID: 29284393 PMCID: PMC6026074 DOI: 10.2174/0929867325666171229132619] [Citation(s) in RCA: 83] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2017] [Revised: 11/22/2017] [Accepted: 12/21/2017] [Indexed: 12/25/2022]
Abstract
G4 DNA is a non-canonical DNA structure consisting of a stacked array of Gquartets held together by base pairing between guanine bases. The formation of G4 DNA requires a cluster of guanine-runs within a strand of DNA. Even though the chemistry of this remarkable DNA structure has been under investigation for decades, evidence supporting the biological relevance of G4 DNA has only begun to emerge and point to very important and conserved biological functions. This review will specifically focus on the interplay between transcription and G4 DNA and discuss two alternative but interconnected perspectives. The first part of the review will describe the evidence substantiating the intriguing idea that a shift in DNA structural conformation could be another layer of non-genetic or epigenetic regulator of gene expression and thereby an important determinant of cell fate. The second part will describe the recent genetic studies showing that those genomic loci containing G4 DNA-forming guanine-rich sequences are potential hotspots of genome instability and that the level and orientation of transcription is critical in the materialization of genome instability associated with these sequences.
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Affiliation(s)
- Nayun Kim
- Department of Microbiology and Molecular Genetics, The University of Texas Health Science Center at Houston; The University of Texas Graduate School of Biomedical Sciences, Houston, TX, United States
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20
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Abstract
R‐loops are potentially mutagenic three‐stranded structures where RNA has hybridized to one strand of DNA and displaced the other, exposing ssDNA . Long repeated R‐loop‐forming sequences are known to cause genomic instability and are associated with disease. Šviković et al (2019 ) show that even short tandem (microsatellite) repeats, abundant in the vertebrate genome, do form R‐loops and present a barrier to replication. However, the replication fork can move past these short R‐loop‐forming repeats through the re‐priming action of primase–polymerase (PrimPol), thus avoiding the loss of epigenetic information or DNA damage.
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Affiliation(s)
- Jane EA Reid
- The John Curtin School of Medical ResearchThe Australian National UniversityCanberraACTAustralia
| | - Tamás Fischer
- The John Curtin School of Medical ResearchThe Australian National UniversityCanberraACTAustralia
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21
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de Oliveira Martins E, Basílio Barbosa V, Weber G. DNA/RNA hybrid mesoscopic model shows strong stability dependence with deoxypyrimidine content and stacking interactions similar to RNA/RNA. Chem Phys Lett 2019. [DOI: 10.1016/j.cplett.2018.11.015] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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22
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Belotserkovskii BP, Tornaletti S, D'Souza AD, Hanawalt PC. R-loop generation during transcription: Formation, processing and cellular outcomes. DNA Repair (Amst) 2018; 71:69-81. [PMID: 30190235 PMCID: PMC6340742 DOI: 10.1016/j.dnarep.2018.08.009] [Citation(s) in RCA: 79] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
R-loops are structures consisting of an RNA-DNA duplex and an unpaired DNA strand. They can form during transcription upon nascent RNA "threadback" invasion into the DNA duplex to displace the non-template strand. Although R-loops occur naturally in all kingdoms of life and serve regulatory roles, they are often deleterious and can cause genomic instability. Of particular importance are the disastrous consequences when replication forks or transcription complexes collide with R-loops. The appropriate processing of R-loops is essential to avoid a number of human neurodegenerative and other clinical disorders. We provide a perspective on mechanistic aspects of R-loop formation and their resolution learned from studies in model systems. This should contribute to improved understanding of R-loop biological functions and enable their practical applications. We propose the novel employment of artificially-generated stable R-loops to selectively inactivate tumor cells.
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Affiliation(s)
- Boris P Belotserkovskii
- Department of Biology, Stanford University, 371 Serra Mall, Stanford, CA, 94305-5020, United States
| | - Silvia Tornaletti
- Department of Biology, Stanford University, 371 Serra Mall, Stanford, CA, 94305-5020, United States
| | - Alicia D D'Souza
- Department of Biology, Stanford University, 371 Serra Mall, Stanford, CA, 94305-5020, United States
| | - Philip C Hanawalt
- Department of Biology, Stanford University, 371 Serra Mall, Stanford, CA, 94305-5020, United States.
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23
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Szlachta K, Thys RG, Atkin ND, Pierce LCT, Bekiranov S, Wang YH. Alternative DNA secondary structure formation affects RNA polymerase II promoter-proximal pausing in human. Genome Biol 2018; 19:89. [PMID: 30001206 PMCID: PMC6042338 DOI: 10.1186/s13059-018-1463-8] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Accepted: 06/13/2018] [Indexed: 01/24/2023] Open
Abstract
BACKGROUND Alternative DNA secondary structures can arise from single-stranded DNA when duplex DNA is unwound during DNA processes such as transcription, resulting in the regulation or perturbation of these processes. We identify sites of high propensity to form stable DNA secondary structure across the human genome using Mfold and ViennaRNA programs with parameters for analyzing DNA. RESULTS The promoter-proximal regions of genes with paused transcription are significantly and energetically more favorable to form DNA secondary structure than non-paused genes or genes without RNA polymerase II (Pol II) binding. Using Pol II ChIP-seq, GRO-seq, NET-seq, and mNET-seq data, we arrive at a robust set of criteria for Pol II pausing, independent of annotation, and find that a highly stable secondary structure is likely to form about 10-50 nucleotides upstream of a Pol II pausing site. Structure probing data confirm the existence of DNA secondary structures enriched at the promoter-proximal regions of paused genes in human cells. Using an in vitro transcription assay, we demonstrate that Pol II pausing at HSPA1B, a human heat shock gene, is affected by manipulating DNA secondary structure upstream of the pausing site. CONCLUSIONS Our results indicate alternative DNA secondary structure formation as a mechanism for how GC-rich sequences regulate RNA Pol II promoter-proximal pausing genome-wide.
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Affiliation(s)
- Karol Szlachta
- Department of Biochemistry and Molecular Genetics, University of Virginia, 1340 Jefferson Park Avenue, Charlottesville, VA, 22908-0733, USA
| | - Ryan G Thys
- Department of Biochemistry and Molecular Genetics, University of Virginia, 1340 Jefferson Park Avenue, Charlottesville, VA, 22908-0733, USA
| | - Naomi D Atkin
- Department of Biochemistry and Molecular Genetics, University of Virginia, 1340 Jefferson Park Avenue, Charlottesville, VA, 22908-0733, USA
| | | | - Stefan Bekiranov
- Department of Biochemistry and Molecular Genetics, University of Virginia, 1340 Jefferson Park Avenue, Charlottesville, VA, 22908-0733, USA.
| | - Yuh-Hwa Wang
- Department of Biochemistry and Molecular Genetics, University of Virginia, 1340 Jefferson Park Avenue, Charlottesville, VA, 22908-0733, USA.
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24
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McGinty RJ, Mirkin SM. Cis- and Trans-Modifiers of Repeat Expansions: Blending Model Systems with Human Genetics. Trends Genet 2018; 34:448-465. [PMID: 29567336 PMCID: PMC5959756 DOI: 10.1016/j.tig.2018.02.005] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Revised: 02/15/2018] [Accepted: 02/19/2018] [Indexed: 12/30/2022]
Abstract
Over 30 hereditary diseases are caused by the expansion of microsatellite repeats. The length of the expandable repeat is the main hereditary determinant of these disorders. They are also affected by numerous genomic variants that are either nearby (cis) or physically separated from (trans) the repetitive locus, which we review here. These genetic variants have largely been elucidated in model systems using gene knockouts, while a few have been directly observed as single-nucleotide polymorphisms (SNPs) in patients. There is a notable disconnect between these two bodies of knowledge: knockouts poorly approximate the SNP-level variation in human populations that gives rise to medically relevant cis- and trans-modifiers, while the rarity of these diseases limits the statistical power of SNP-based analysis in humans. We propose that high-throughput SNP-based screening in model systems could become a useful approach to quickly identify and characterize modifiers of clinical relevance for patients.
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Affiliation(s)
- Ryan J McGinty
- Department of Biology, Tufts University, Medford, MA 02155, USA
| | - Sergei M Mirkin
- Department of Biology, Tufts University, Medford, MA 02155, USA.
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25
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D'Souza AD, Belotserkovskii BP, Hanawalt PC. A novel mode for transcription inhibition mediated by PNA-induced R-loops with a model in vitro system. BIOCHIMICA ET BIOPHYSICA ACTA. GENE REGULATORY MECHANISMS 2018; 1861:158-166. [PMID: 29357316 PMCID: PMC5820110 DOI: 10.1016/j.bbagrm.2017.12.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Revised: 12/20/2017] [Accepted: 12/20/2017] [Indexed: 01/01/2023]
Abstract
The selective inhibition of transcription of a chosen gene by an artificial agent has numerous applications. Usually, these agents are designed to bind a specific nucleotide sequence in the promoter or within the transcribed region of the chosen gene. However, since optimal binding sites might not exist within the gene, it is of interest to explore the possibility of transcription inhibition when the agent is designed to bind at other locations. One of these possibilities arises when an additional transcription initiation site (e.g. secondary promoter) is present upstream from the primary promoter of the target gene. In this case, transcription inhibition might be achieved by inducing the formation of an RNA-DNA hybrid (R-loop) upon transcription from the secondary promoter. The R-loop could extend into the region of the primary promoter, to interfere with promoter recognition by RNA polymerase and thereby inhibit transcription. As a sequence-specific R-loop-inducing agent, a peptide nucleic acid (PNA) could be designed to facilitate R-loop formation by sequestering the non-template DNA strand. To investigate this mode for transcription inhibition, we have employed a model system in which a PNA binding site is localized between the T3 and T7 phage RNA polymerase promoters, which respectively assume the roles of primary and secondary promoters. In accord with our model, we have demonstrated that with PNA-bound DNA substrates, transcription from the T7 promoter reduces transcription from the T3 promoter by 30-fold, while in the absence of PNA binding there is no significant effect of T7 transcription upon T3 transcription.
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Affiliation(s)
- Alicia D D'Souza
- Department of Biology, Stanford University, Stanford, CA 94305-5020, United States
| | | | - Philip C Hanawalt
- Department of Biology, Stanford University, Stanford, CA 94305-5020, United States.
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26
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Belotserkovskii BP, Soo Shin JH, Hanawalt PC. Strong transcription blockage mediated by R-loop formation within a G-rich homopurine-homopyrimidine sequence localized in the vicinity of the promoter. Nucleic Acids Res 2017; 45:6589-6599. [PMID: 28498974 PMCID: PMC5499740 DOI: 10.1093/nar/gkx403] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Accepted: 05/08/2017] [Indexed: 02/07/2023] Open
Abstract
Guanine-rich (G-rich) homopurine–homopyrimidine nucleotide sequences can block transcription with an efficiency that depends upon their orientation, composition and length, as well as the presence of negative supercoiling or breaks in the non-template DNA strand. We report that a G-rich sequence in the non-template strand reduces the yield of T7 RNA polymerase transcription by more than an order of magnitude when positioned close (9 bp) to the promoter, in comparison to that for a distal (∼250 bp) location of the same sequence. This transcription blockage is much less pronounced for a C-rich sequence, and is not significant for an A-rich sequence. Remarkably, the blockage is not pronounced if transcription is performed in the presence of RNase H, which specifically digests the RNA strands within RNA–DNA hybrids. The blockage also becomes less pronounced upon reduced RNA polymerase concentration. Based upon these observations and those from control experiments, we conclude that the blockage is primarily due to the formation of stable RNA–DNA hybrids (R-loops), which inhibit successive rounds of transcription. Our results could be relevant to transcription dynamics in vivo (e.g. transcription ‘bursting’) and may also have practical implications for the design of expression vectors.
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Affiliation(s)
| | - Jane Hae Soo Shin
- Department of Biology, Stanford University, Stanford, CA 94305-5020, USA
| | - Philip C Hanawalt
- Department of Biology, Stanford University, Stanford, CA 94305-5020, USA
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27
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Applications of PNA-Based Artificial Restriction DNA Cutters. Molecules 2017; 22:molecules22101586. [PMID: 28934140 PMCID: PMC6151779 DOI: 10.3390/molecules22101586] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2017] [Revised: 09/16/2017] [Accepted: 09/18/2017] [Indexed: 12/14/2022] Open
Abstract
More than ten years ago, artificial restriction DNA cutters were developed by combining two pseudo-complementary peptide nucleic acid (pcPNA) strands with either Ce(IV)/EDTA or S1 nuclease. They have remarkably high site-specificity and can cut only one predetermined site in the human genome. In this article, recent progress of these man-made tools have been reviewed. By cutting the human genome site-selectively, desired fragments can be clipped from either the termini of chromosomes (telomeres) or from the middle of genome. These fragments should provide important information on the biological functions of complicated genome system. DNA/RNA hybrid duplexes, which are formed in living cells, are also site-selectively hydrolyzed by these cutters. In order to further facilitate the applications of the artificial DNA cutters, various chemical modifications have been attempted. One of the most important successes is preparation of PNA derivatives which can form double-duplex invasion complex even under high salt conditions. This is important for in vivo applications, since the inside of living cells is abundant of metal ions. Furthermore, site-selective DNA cutters which require only one PNA strand, in place of a pair of pcPNA strands, are developed. This progress has opened a way to new fields of PNA-based biochemistry and biotechnology.
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28
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Abstract
Topoisomerases manage the torsional stress associated with the separation of DNA strands during transcription and DNA replication. Eukaryotic Topoisomerase I (Top1) is a Type IB enzyme that nicks and rejoins only one strand of duplex DNA, and it is especially important during transcription. By resolving transcription-associated torsional stress, Top1 reduces the accumulation of genome-destabilizing R-loops and non-B DNA structures. The DNA nicking activity of Top1, however, can also initiate genome instability in the form of illegitimate recombination, homologous recombination and mutagenesis. In this review, we focus on the diverse, and often opposing, roles of Top1 in regulating eukaryotic genome stability.
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29
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Shafiq S, Chen C, Yang J, Cheng L, Ma F, Widemann E, Sun Q. DNA Topoisomerase 1 Prevents R-loop Accumulation to Modulate Auxin-Regulated Root Development in Rice. MOLECULAR PLANT 2017; 10:821-833. [PMID: 28412545 DOI: 10.1016/j.molp.2017.04.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Revised: 03/02/2017] [Accepted: 04/03/2017] [Indexed: 05/21/2023]
Abstract
R-loop structures (RNA:DNA hybrids) have important functions in many biological processes, including transcriptional regulation and genome instability among diverse organisms. DNA topoisomerase 1 (TOP1), an essential manipulator of DNA topology during RNA transcription and DNA replication processes, can prevent R-loop accumulation by removing the positive and negative DNA supercoiling that is made by RNA polymerases during transcription. TOP1 is required for plant development, but little is known about its function in preventing co-transcriptional R-loop accumulation in various biological processes in plants. Here we show that knockdown of OsTOP1 strongly affects rice development, causing defects in root architecture and gravitropism, which are the consequences of misregulation of auxin signaling and transporter genes. We found that R-loops are naturally formed at rice auxin-related gene loci, and overaccumulate when OsTOP1 is knocked down or OsTOP1 protein activity is inhibited. OsTOP1 therefore sets the accurate expression levels of auxin-related genes by preventing the overaccumulation of inherent R-loops. Our data reveal R-loops as important factors in polar auxin transport and plant root development, and highlight that OsTOP1 functions as a key to link transcriptional R-loops with plant hormone signaling, provide new insights into transcriptional regulation of hormone signaling in plants.
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Affiliation(s)
- Sarfraz Shafiq
- Center for Plant Biology and Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China; Permanent affiliation: Department of Environmental Sciences, COMSATS Institute of Information Technology, Abbottabad 22060, Pakistan
| | - Chunli Chen
- College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, China.
| | - Jing Yang
- College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, China
| | - Lingling Cheng
- Center for Plant Biology and Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Fei Ma
- College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, China
| | - Emilie Widemann
- Center for Plant Biology and Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Qianwen Sun
- Center for Plant Biology and Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China.
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30
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Menoni H, Di Mascio P, Cadet J, Dimitrov S, Angelov D. Chromatin associated mechanisms in base excision repair - nucleosome remodeling and DNA transcription, two key players. Free Radic Biol Med 2017; 107:159-169. [PMID: 28011149 DOI: 10.1016/j.freeradbiomed.2016.12.026] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Revised: 12/13/2016] [Accepted: 12/19/2016] [Indexed: 12/30/2022]
Abstract
Genomic DNA is prone to a large number of insults by a myriad of endogenous and exogenous agents. The base excision repair (BER) is the major mechanism used by cells for the removal of various DNA lesions spontaneously or environmentally induced and the maintenance of genome integrity. The presence of persistent DNA damage is not compatible with life, since abrogation of BER leads to early embryonic lethality in mice. There are several lines of evidences showing existence of a link between deficient BER, cancer proneness and ageing, thus illustrating the importance of this DNA repair pathway in human health. Although the enzymology of BER mechanisms has been largely elucidated using chemically defined DNA damage substrates and purified proteins, the complex interplay of BER with another vital process like transcription or when DNA is in its natural state (i.e. wrapped in nucleosome and assembled in chromatin fiber is largely unexplored. Cells use chromatin remodeling factors to overcome the general repression associated with the nucleosomal organization. It is broadly accepted that energy-dependent nucleosome remodeling factors disrupt histones-DNA interactions at the expense of ATP hydrolysis to favor transcription as well as DNA repair. Importantly, unlike transcription, BER is not part of a regulated developmental process but represents a maintenance system that should be efficient anytime and anywhere in the genome. In this review we will discuss how BER can deal with chromatin organization to maintain genetic information. Emphasis will be placed on the following challenging question: how BER is initiated within chromatin?
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Affiliation(s)
- Hervé Menoni
- Laboratoire de Biologie et Modélisation de la Cellule (LBMC) CNRS/ENSL/UCBL UMR 5239 and Institut NeuroMyoGène - INMG CNRS/UCBL UMR 5310, Université de Lyon, Ecole Normale Supérieure de Lyon, 69007 Lyon, France; Université de Grenoble Alpes/INSERM U1209/CNRS UMR 5309, 38042 Grenoble Cedex 9, France.
| | - Paolo Di Mascio
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, CP 26077, CEP 05508-000 São Paulo, SP, Brazil
| | - Jean Cadet
- Département de Médecine Nucléaire et de Radiobiologie, Université de Sherbrooke, Sherbrooke, Québec, Canada J1H 5N4
| | - Stefan Dimitrov
- Université de Grenoble Alpes/INSERM U1209/CNRS UMR 5309, 38042 Grenoble Cedex 9, France
| | - Dimitar Angelov
- Laboratoire de Biologie et Modélisation de la Cellule (LBMC) CNRS/ENSL/UCBL UMR 5239 and Institut NeuroMyoGène - INMG CNRS/UCBL UMR 5310, Université de Lyon, Ecole Normale Supérieure de Lyon, 69007 Lyon, France.
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31
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Physiological functions of programmed DNA breaks in signal-induced transcription. Nat Rev Mol Cell Biol 2017; 18:471-476. [PMID: 28537575 DOI: 10.1038/nrm.2017.43] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The idea that signal-dependent transcription might involve the generation of transient DNA nicks or even breaks in the regulatory regions of genes, accompanied by activation of DNA damage repair pathways, would seem to be counterintuitive, as DNA damage is usually considered harmful to cellular integrity. However, recent studies have generated a substantial body of evidence that now argues that programmed DNA single- or double-strand breaks can, at least in specific cases, have a role in transcription regulation. Here, we discuss the emerging functions of DNA breaks in the relief of DNA torsional stress and in promoter and enhancer activation.
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32
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Pipathsouk A, Belotserkovskii BP, Hanawalt PC. When transcription goes on Holliday: Double Holliday junctions block RNA polymerase II transcription in vitro. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2016; 1860:282-288. [PMID: 27923713 DOI: 10.1016/j.bbagrm.2016.12.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Revised: 11/22/2016] [Accepted: 12/02/2016] [Indexed: 01/04/2023]
Abstract
Non-canonical DNA structures can obstruct transcription. This transcription blockage could have various biological consequences, including genomic instability and gratuitous transcription-coupled repair. Among potential structures causing transcription blockage are Holliday junctions (HJs), which can be generated as intermediates in homologous recombination or during processing of stalled replication forks. Of particular interest is the double Holliday junction (DHJ), which contains two HJs. Topological considerations impose the constraint that the total number of helical turns in the DNA duplexes between the junctions cannot be altered as long as the flanking DNA duplexes are intact. Thus, the DHJ structure should strongly resist transient unwinding during transcription; consequently, it is predicted to cause significantly stronger blockage than single HJ structures. The patterns of transcription blockage obtained for RNA polymerase II transcription in HeLa cell nuclear extracts were in accordance with this prediction. However, we did not detect transcription blockage with purified T7 phage RNA polymerase; we discuss a possible explanation for this difference. In general, our findings implicate naturally occurring Holliday junctions in transcription arrest.
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Affiliation(s)
- Anne Pipathsouk
- Department of Biology, Stanford University, Stanford, CA 94305, USA
| | | | - Philip C Hanawalt
- Department of Biology, Stanford University, Stanford, CA 94305, USA.
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33
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Transient RNA-DNA Hybrids Are Required for Efficient Double-Strand Break Repair. Cell 2016; 167:1001-1013.e7. [DOI: 10.1016/j.cell.2016.10.001] [Citation(s) in RCA: 259] [Impact Index Per Article: 32.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Revised: 08/16/2016] [Accepted: 09/29/2016] [Indexed: 11/19/2022]
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34
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Topoisomerase IB of Deinococcus radiodurans resolves guanine quadruplex DNA structures in vitro. J Biosci 2015; 40:833-43. [DOI: 10.1007/s12038-015-9571-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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35
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Xu L, Wang W, Chong J, Shin JH, Xu J, Wang D. RNA polymerase II transcriptional fidelity control and its functional interplay with DNA modifications. Crit Rev Biochem Mol Biol 2015; 50:503-19. [PMID: 26392149 DOI: 10.3109/10409238.2015.1087960] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Accurate genetic information transfer is essential for life. As a key enzyme involved in the first step of gene expression, RNA polymerase II (Pol II) must maintain high transcriptional fidelity while it reads along DNA template and synthesizes RNA transcript in a stepwise manner during transcription elongation. DNA lesions or modifications may lead to significant changes in transcriptional fidelity or transcription elongation dynamics. In this review, we will summarize recent progress toward understanding the molecular basis of RNA Pol II transcriptional fidelity control and impacts of DNA lesions and modifications on Pol II transcription elongation.
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Affiliation(s)
- Liang Xu
- a Skaggs School of Pharmacy and Pharmaceutical Sciences, The University of California San Diego , La Jolla , CA , USA
| | - Wei Wang
- a Skaggs School of Pharmacy and Pharmaceutical Sciences, The University of California San Diego , La Jolla , CA , USA
| | - Jenny Chong
- a Skaggs School of Pharmacy and Pharmaceutical Sciences, The University of California San Diego , La Jolla , CA , USA
| | - Ji Hyun Shin
- a Skaggs School of Pharmacy and Pharmaceutical Sciences, The University of California San Diego , La Jolla , CA , USA
| | - Jun Xu
- a Skaggs School of Pharmacy and Pharmaceutical Sciences, The University of California San Diego , La Jolla , CA , USA
| | - Dong Wang
- a Skaggs School of Pharmacy and Pharmaceutical Sciences, The University of California San Diego , La Jolla , CA , USA
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36
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Chromatin, DNA structure and alternative splicing. FEBS Lett 2015; 589:3370-8. [PMID: 26296319 DOI: 10.1016/j.febslet.2015.08.002] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Revised: 07/31/2015] [Accepted: 08/04/2015] [Indexed: 02/07/2023]
Abstract
Coupling of transcription and alternative splicing via regulation of the transcriptional elongation rate is a well-studied phenomenon. Template features that act as roadblocks for the progression of RNA polymerase II comprise histone modifications and variants, DNA-interacting proteins and chromatin compaction. These may affect alternative splicing decisions by inducing pauses or decreasing elongation rate that change the time-window for splicing regulatory sequences to be recognized. Herein we discuss the evidence supporting the influence of template structural modifications on transcription and splicing, and provide insights about possible roles of non-B DNA conformations on the regulation of alternative splicing.
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37
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Khodursky A, Guzmán EC, Hanawalt PC. Thymineless Death Lives On: New Insights into a Classic Phenomenon. Annu Rev Microbiol 2015; 69:247-63. [PMID: 26253395 DOI: 10.1146/annurev-micro-092412-155749] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The primary mechanisms by which bacteria lose viability when deprived of thymine have been elusive for over half a century. Early research focused on stalled replication forks and the deleterious effects of uracil incorporation into DNA from thymidine-deficient nucleotide pools. The initiation of the replication cycle and origin-proximal DNA degradation during thymine starvation have now been quantified via whole-genome microarrays and other approaches. These advances have fostered innovative models and informative experiments in bacteria since this topic was last reviewed. Given that thymineless death is similar in mammalian cells and that certain antibacterial and chemotherapeutic drugs elicit thymine deficiency, a mechanistic understanding of this phenomenon might have valuable biomedical applications.
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Affiliation(s)
- Arkady Khodursky
- Biotechnology Institute and Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, St. Paul, Minnesota 55108;
| | - Elena C Guzmán
- Departamento de Bioquímica Biología Molecular y Genética, Universidad de Extremadura, 06071 Badajoz, Spain;
| | - Philip C Hanawalt
- Department of Biology, Stanford University, Stanford, California 94305;
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38
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Abstract
Structure-prone DNA repeats are common components of genomic DNA in all kingdoms of life. In humans, these repeats are linked to genomic instabilities that result in various hereditary disorders, including many cancers. It has long been known that DNA repeats are not only highly polymorphic in length but can also cause chromosomal fragility and stimulate gross chromosomal rearrangements, i.e., deletions, duplications, inversions, translocations and more complex shuffles. More recently, it has become clear that inherently unstable DNA repeats dramatically elevate mutation rates in surrounding DNA segments and that these mutations can occur up to ten kilobases away from the repetitive tract, a phenomenon we call repeat-induced mutagenesis (RIM). This review describes experimental data that led to the discovery and characterization of RIM and discusses the molecular mechanisms that could account for this phenomenon.
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Affiliation(s)
- Kartik A Shah
- Department of Biology, Tufts University, Medford, MA 02155, USA
| | - Sergei M Mirkin
- Department of Biology, Tufts University, Medford, MA 02155, USA.
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39
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Pestov NA, Gerasimova NS, Kulaeva OI, Studitsky VM. Structure of transcribed chromatin is a sensor of DNA damage. SCIENCE ADVANCES 2015; 1:e1500021. [PMID: 26601207 PMCID: PMC4646769 DOI: 10.1126/sciadv.1500021] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Accepted: 05/03/2015] [Indexed: 06/05/2023]
Abstract
Early detection and repair of damaged DNA is essential for cell functioning and survival. Although multiple cellular systems are involved in the repair of single-strand DNA breaks (SSBs), it remains unknown how SSBs present in the nontemplate strand (NT-SSBs) of DNA organized in chromatin are detected. The effect of NT-SSBs on transcription through chromatin by RNA polymerase II was studied. NT-SSBs localized in the promoter-proximal region of nucleosomal DNA and hidden in the nucleosome structure can induce a nearly quantitative arrest of RNA polymerase downstream of the break, whereas more promoter-distal SSBs moderately facilitate transcription. The location of the arrest sites on nucleosomal DNA suggests that formation of small intranucleosomal DNA loops causes the arrest. This mechanism likely involves relief of unconstrained DNA supercoiling accumulated during transcription through chromatin by NT-SSBs. These data suggest the existence of a novel chromatin-specific mechanism that allows the detection of NT-SSBs by the transcribing enzyme.
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Affiliation(s)
- Nikolay A. Pestov
- Department of Pharmacology, Rutgers Robert Wood Johnson Medical School, Piscataway, NJ 08854, USA
| | | | - Olga I. Kulaeva
- Biology Faculty, Lomonosov Moscow State University, Moscow, Russia
- Fox Chase Cancer Center, Philadelphia, PA 19111, USA
| | - Vasily M. Studitsky
- Department of Pharmacology, Rutgers Robert Wood Johnson Medical School, Piscataway, NJ 08854, USA
- Biology Faculty, Lomonosov Moscow State University, Moscow, Russia
- Fox Chase Cancer Center, Philadelphia, PA 19111, USA
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40
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Pandey S, Ogloblina AM, Belotserkovskii BP, Dolinnaya NG, Yakubovskaya MG, Mirkin SM, Hanawalt PC. Transcription blockage by stable H-DNA analogs in vitro. Nucleic Acids Res 2015; 43:6994-7004. [PMID: 26101261 PMCID: PMC4538819 DOI: 10.1093/nar/gkv622] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Accepted: 06/03/2015] [Indexed: 11/14/2022] Open
Abstract
DNA sequences that can form unusual secondary structures are implicated in regulating gene expression and causing genomic instability. H-palindromes are an important class of such DNA sequences that can form an intramolecular triplex structure, H-DNA. Within an H-palindrome, the H-DNA and canonical B-DNA are in a dynamic equilibrium that shifts toward H-DNA with increased negative supercoiling. The interplay between H- and B-DNA and the fact that the process of transcription affects supercoiling makes it difficult to elucidate the effects of H-DNA upon transcription. We constructed a stable structural analog of H-DNA that cannot flip into B-DNA, and studied the effects of this structure on transcription by T7 RNA polymerase in vitro. We found multiple transcription blockage sites adjacent to and within sequences engaged in this triplex structure. Triplex-mediated transcription blockage varied significantly with changes in ambient conditions: it was exacerbated in the presence of Mn(2+) or by increased concentrations of K(+) and Li(+). Analysis of the detailed pattern of the blockage suggests that RNA polymerase is sterically hindered by H-DNA and has difficulties in unwinding triplex DNA. The implications of these findings for the biological roles of triple-stranded DNA structures are discussed.
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Affiliation(s)
- Shristi Pandey
- Department of Biology, Stanford University, Stanford, CA 94305, USA
| | | | | | - Nina G Dolinnaya
- Department of Chemistry, Lomonosov Moscow State University, Moscow, Russia
| | | | - Sergei M Mirkin
- Department of Biology, Tufts University, Medford, MA 02155, USA
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41
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Belotserkovskii BP, Hanawalt PC. 24 Interference of PNA binding to the non-template strand with transcription supports the general model for transcription blockage by R-loop formation. J Biomol Struct Dyn 2015. [DOI: 10.1080/07391102.2015.1032564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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42
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Komiyama M. Chemical modifications of artificial restriction DNA cutter (ARCUT) to promote its in vivo and in vitro applications. ARTIFICIAL DNA, PNA & XNA 2014; 5:e1112457. [PMID: 26744220 PMCID: PMC5329899 DOI: 10.1080/1949095x.2015.1112457] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Revised: 10/14/2015] [Accepted: 10/15/2015] [Indexed: 05/10/2023]
Abstract
Recently, completely chemistry-based tools for site-selective scission of DNA (ARCUT) have been prepared by combining 2 strands of pseudo-complementary PNA (pcPNA: site-selective activator) and a Ce(IV)-EDTA complex (molecular scissors). Its site-specificity is sufficient to cut the whole human genome at one predetermined site. In this first-generation ARCUT, however, there still remain several problems to be solved for wider applications. This review presents recent approaches to solve these problems. They are divided into (i) covalent modification of pcPNA with other functional groups and (ii) new strategies using conventional PNA, in place of pcPNA, as site-selective activator. Among various chemical modifications, conjugation with positively-charged nuclear localization signal peptide is especially effective. Furthermore, unimolecular activators, a single strand of which successfully activates the target site in DNA for site-selective scission, have been also developed. As the result of these modifications, the site-selective scission by Ce(IV)-EDTA was achieved promptly even under high salt conditions which are otherwise unfavourable for double-duplex invasion. Furthermore, it has been shown that "molecular crowding effect," which characterizes the inside of living cells, enormously promotes the invasion, and thus the invasion seems to proceed effectively and spontaneously in the cells. Strong potential of pcPNA for further applications in vivo and in vitro has been confirmed.
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Affiliation(s)
- Makoto Komiyama
- Life Science Center of Tsukuba Advanced Research Alliance; University of Tsukuba; Tsukuba, Ibaraki, Japan
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43
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Yadav P, Harcy V, Argueso JL, Dominska M, Jinks-Robertson S, Kim N. Topoisomerase I plays a critical role in suppressing genome instability at a highly transcribed G-quadruplex-forming sequence. PLoS Genet 2014; 10:e1004839. [PMID: 25473964 PMCID: PMC4256205 DOI: 10.1371/journal.pgen.1004839] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Accepted: 10/20/2014] [Indexed: 11/18/2022] Open
Abstract
G-quadruplex or G4 DNA is a non-B secondary DNA structure that comprises a stacked array of guanine-quartets. Cellular processes such as transcription and replication can be hindered by unresolved DNA secondary structures potentially endangering genome maintenance. As G4-forming sequences are highly frequent throughout eukaryotic genomes, it is important to define what factors contribute to a G4 motif becoming a hotspot of genome instability. Using a genetic assay in Saccharomyces cerevisiae, we previously demonstrated that a potential G4-forming sequence derived from a guanine-run containing immunoglobulin switch Mu (Sμ) region becomes highly unstable when actively transcribed. Here we describe assays designed to survey spontaneous genome rearrangements initiated at the Sμ sequence in the context of large genomic areas. We demonstrate that, in the absence of Top1, a G4 DNA-forming sequence becomes a strong hotspot of gross chromosomal rearrangements and loss of heterozygosity associated with mitotic recombination within the ∼20 kb or ∼100 kb regions of yeast chromosome V or III, respectively. Transcription confers a critical strand bias since genome rearrangements at the G4-forming Sμ are elevated only when the guanine-runs are located on the non-transcribed strand. The direction of replication and transcription, when in a head-on orientation, further contribute to the elevated genome instability at a potential G4 DNA-forming sequence. The implications of our identification of Top1 as a critical factor in suppression of instability associated with potential G4 DNA-forming sequences are discussed. Genome instability is not evenly distributed, but rather is highly elevated at certain genomic loci containing DNA sequences that can fold into non-canonical secondary structures. The four-stranded G-quadruplex or G4 DNA is one such DNA structure capable of instigating transcription and/or replication obstruction and subsequent genome instability. In this study, we used a reporter system to quantitatively measure the level of genome instability occurring at a G4 DNA motif integrated into the yeast genome. We showed that the disruption of Topoisomerase I function significantly elevated various types of genome instability at the highly transcribed G4 motif generating loss of heterozygosity and copy number alterations (deletions and duplications), both of which are frequently observed in cancer genomes.
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Affiliation(s)
- Puja Yadav
- Department of Microbiology and Molecular Genetics, University of Texas Health Science Center at Houston, Houston, Texas, United States of America
| | - Victoria Harcy
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - Juan Lucas Argueso
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - Margaret Dominska
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Sue Jinks-Robertson
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Nayun Kim
- Department of Microbiology and Molecular Genetics, University of Texas Health Science Center at Houston, Houston, Texas, United States of America
- * E-mail:
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44
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Felipe-Abrio I, Lafuente-Barquero J, García-Rubio ML, Aguilera A. RNA polymerase II contributes to preventing transcription-mediated replication fork stalls. EMBO J 2014; 34:236-50. [PMID: 25452497 DOI: 10.15252/embj.201488544] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Transcription is a major contributor to genome instability. A main cause of transcription-associated instability relies on the capacity of transcription to stall replication. However, we know little of the possible role, if any, of the RNA polymerase (RNAP) in this process. Here, we analyzed 4 specific yeast RNAPII mutants that show different phenotypes of genetic instability including hyper-recombination, DNA damage sensitivity and/or a strong dependency on double-strand break repair functions for viability. Three specific alleles of the RNAPII core, rpb1-1, rpb1-S751F and rpb9∆, cause a defect in replication fork progression, compensated for by additional origin firing, as the main action responsible for instability. The transcription elongation defects of rpb1-S751F and rpb9∆ plus our observation that rpb1-1 causes RNAPII retention on chromatin suggest that RNAPII could participate in facilitating fork progression upon a transcription-replication encounter. Our results imply that the RNAPII or ancillary factors actively help prevent transcription-associated genome instability.
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Affiliation(s)
- Irene Felipe-Abrio
- Centro Andaluz de Biología Molecular y Medicina Regenerativa CABIMER, Universidad de Sevilla, Seville, Spain
| | - Juan Lafuente-Barquero
- Centro Andaluz de Biología Molecular y Medicina Regenerativa CABIMER, Universidad de Sevilla, Seville, Spain
| | - María L García-Rubio
- Centro Andaluz de Biología Molecular y Medicina Regenerativa CABIMER, Universidad de Sevilla, Seville, Spain
| | - Andrés Aguilera
- Centro Andaluz de Biología Molecular y Medicina Regenerativa CABIMER, Universidad de Sevilla, Seville, Spain
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45
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Belotserkovskii BP, Hanawalt PC. PNA binding to the non-template DNA strand interferes with transcription, suggesting a blockage mechanism mediated by R-loop formation. Mol Carcinog 2014; 54:1508-12. [PMID: 25175074 DOI: 10.1002/mc.22209] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Revised: 06/26/2014] [Accepted: 07/03/2014] [Indexed: 11/10/2022]
Abstract
Peptide Nucleic Acids (PNAs) are artificial DNA mimics with superior nucleic acid binding capabilities. T7 RNA polymerase (T7 RNAP) transcription upon encountering PNA bound to the non-template DNA strand was studied in vitro. A characteristic pattern of blockage signals was observed, extending downstream from the PNA binding site, similar to that produced by G-rich homopurine-homopyrimidine (hPu-hPy) sequences and likely caused by R-loop formation. Since blocked transcription complexes in association with stable R-loops may interfere with replication and in some cases trigger apoptosis, targeted R-loop formation might be employed to inactivate selected cells, such as those in tumors, based upon their unique complement of expressed genes.
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46
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Britton S, Dernoncourt E, Delteil C, Froment C, Schiltz O, Salles B, Frit P, Calsou P. DNA damage triggers SAF-A and RNA biogenesis factors exclusion from chromatin coupled to R-loops removal. Nucleic Acids Res 2014; 42:9047-62. [PMID: 25030905 PMCID: PMC4132723 DOI: 10.1093/nar/gku601] [Citation(s) in RCA: 129] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
We previously identified the heterogeneous ribonucleoprotein SAF-A/hnRNP U as a substrate for DNA-PK, a protein kinase involved in DNA damage response (DDR). Using laser micro-irradiation in human cells, we report here that SAF-A exhibits a two-phase dynamics at sites of DNA damage, with a rapid and transient recruitment followed by a prolonged exclusion. SAF-A recruitment corresponds to its binding to Poly(ADP-ribose) while its exclusion is dependent on the activity of ATM, ATR and DNA-PK and reflects the dissociation from chromatin of SAF-A associated with ongoing transcription. Having established that SAF-A RNA-binding domain recapitulates SAF-A dynamics, we show that this domain is part of a complex comprising several mRNA biogenesis proteins of which at least two, FUS/TLS and TAFII68/TAF15, exhibit similar biphasic dynamics at sites of damage. Using an original reporter for live imaging of DNA:RNA hybrids (R-loops), we show a transient transcription-dependent accumulation of R-loops at sites of DNA damage that is prolonged upon inhibition of RNA biogenesis factors exclusion. We propose that a new component of the DDR is an active anti-R-loop mechanism operating at damaged transcribed sites which includes the exclusion of mRNA biogenesis factors such as SAF-A, FUS and TAF15.
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Affiliation(s)
- Sébastien Britton
- CNRS, IPBS (Institut de Pharmacologie et de Biologie Structurale), BP 64182, 205 route de Narbonne, F-31077 Toulouse, Cedex 4, France Université de Toulouse, UPS, IPBS, F-31077 Toulouse, France Equipe Labellisée Ligue Nationale Contre le Cancer
| | - Emma Dernoncourt
- CNRS, IPBS (Institut de Pharmacologie et de Biologie Structurale), BP 64182, 205 route de Narbonne, F-31077 Toulouse, Cedex 4, France Université de Toulouse, UPS, IPBS, F-31077 Toulouse, France Equipe Labellisée Ligue Nationale Contre le Cancer
| | - Christine Delteil
- CNRS, IPBS (Institut de Pharmacologie et de Biologie Structurale), BP 64182, 205 route de Narbonne, F-31077 Toulouse, Cedex 4, France Université de Toulouse, UPS, IPBS, F-31077 Toulouse, France Equipe Labellisée Ligue Nationale Contre le Cancer
| | - Carine Froment
- CNRS, IPBS (Institut de Pharmacologie et de Biologie Structurale), BP 64182, 205 route de Narbonne, F-31077 Toulouse, Cedex 4, France Université de Toulouse, UPS, IPBS, F-31077 Toulouse, France
| | - Odile Schiltz
- CNRS, IPBS (Institut de Pharmacologie et de Biologie Structurale), BP 64182, 205 route de Narbonne, F-31077 Toulouse, Cedex 4, France Université de Toulouse, UPS, IPBS, F-31077 Toulouse, France
| | - Bernard Salles
- CNRS, IPBS (Institut de Pharmacologie et de Biologie Structurale), BP 64182, 205 route de Narbonne, F-31077 Toulouse, Cedex 4, France Université de Toulouse, UPS, IPBS, F-31077 Toulouse, France
| | - Philippe Frit
- CNRS, IPBS (Institut de Pharmacologie et de Biologie Structurale), BP 64182, 205 route de Narbonne, F-31077 Toulouse, Cedex 4, France Université de Toulouse, UPS, IPBS, F-31077 Toulouse, France Equipe Labellisée Ligue Nationale Contre le Cancer
| | - Patrick Calsou
- CNRS, IPBS (Institut de Pharmacologie et de Biologie Structurale), BP 64182, 205 route de Narbonne, F-31077 Toulouse, Cedex 4, France Université de Toulouse, UPS, IPBS, F-31077 Toulouse, France Equipe Labellisée Ligue Nationale Contre le Cancer
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47
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Xu L, Da L, Plouffe SW, Chong J, Kool E, Wang D. Molecular basis of transcriptional fidelity and DNA lesion-induced transcriptional mutagenesis. DNA Repair (Amst) 2014; 19:71-83. [PMID: 24767259 DOI: 10.1016/j.dnarep.2014.03.024] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Maintaining high transcriptional fidelity is essential for life. Some DNA lesions lead to significant changes in transcriptional fidelity. In this review, we will summarize recent progress towards understanding the molecular basis of RNA polymerase II (Pol II) transcriptional fidelity and DNA lesion-induced transcriptional mutagenesis. In particular, we will focus on the three key checkpoint steps of controlling Pol II transcriptional fidelity: insertion (specific nucleotide selection and incorporation), extension (differentiation of RNA transcript extension of a matched over mismatched 3'-RNA terminus), and proofreading (preferential removal of misincorporated nucleotides from the 3'-RNA end). We will also discuss some novel insights into the molecular basis and chemical perspectives of controlling Pol II transcriptional fidelity through structural, computational, and chemical biology approaches.
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Affiliation(s)
- Liang Xu
- Skaggs School of Pharmacy and Pharmaceutical Science, University of California San Diego, La Jolla, CA 92093-0625, United States
| | - Linati Da
- Skaggs School of Pharmacy and Pharmaceutical Science, University of California San Diego, La Jolla, CA 92093-0625, United States
| | - Steven W Plouffe
- Skaggs School of Pharmacy and Pharmaceutical Science, University of California San Diego, La Jolla, CA 92093-0625, United States
| | - Jenny Chong
- Skaggs School of Pharmacy and Pharmaceutical Science, University of California San Diego, La Jolla, CA 92093-0625, United States
| | - Eric Kool
- Department of Chemistry, Stanford University, Stanford, CA 94305-5080, United States.
| | - Dong Wang
- Skaggs School of Pharmacy and Pharmaceutical Science, University of California San Diego, La Jolla, CA 92093-0625, United States.
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48
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Belotserkovskii BP. Relationships between the winding angle, the characteristic radius, and the torque for a long polymer chain wound around a cylinder: implications for RNA winding around DNA during transcription. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2014; 89:022709. [PMID: 25353511 DOI: 10.1103/physreve.89.022709] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2013] [Indexed: 06/04/2023]
Abstract
Long polymer chains are ubiquitous in biological systems and their mechanical properties have significant impact upon biological processes. Of particular interest is the situation in which polymer chains are wound around each other or around other objects. We have analyzed the parameters of a long Gaussian polymer chain wound around a cylinder as a function of the torque applied to the ends of the chain. We have shown that for sufficiently long polymer chains, an average winding angle and a characteristic radius of the chain can be determined from a modified Bessel function of purely imaginary order, in which the value of the order is equivalent to the applied torque, normalized to the product of the absolute temperature and the Boltzmann constant. The obtained results are consistent with a simplified interpretation in terms of "torsional blobs," and this could be extended to nonideal chains with excluded volumes. We have also extended our results to the case of a polymer chain rotating in viscous medium. Our results could be used to estimate the mechanical strains that appear in DNA and RNA during transcription, as these might initiate formation of unusual DNA structures, invasion of RNA into the DNA duplex (R-loop formation), and modulation of the interactions of DNA and RNA with proteins.
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Affiliation(s)
- Boris P Belotserkovskii
- Department of Biology, Stanford University, 371 Serra Mall, Herrin Labs, Stanford, California 94305-5020, USA
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49
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Xiao X, Agris PF, Hall CK. Molecular recognition mechanism of peptide chain bound to the tRNA(Lys3) anticodon loop in silico. J Biomol Struct Dyn 2014; 33:14-27. [PMID: 24417415 DOI: 10.1080/07391102.2013.869660] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
The mechanism by which proteins recognize and bind the post-transcriptional modifications of RNAs is unknown, yet these interactions play important functions in biology. Atomistic molecular dynamics simulations were performed to examine the folding of the model peptide chain -RVTHHAFLGAHRTVG- and the complex formed by the folded peptide with the native anticodon stem and loop of the human tRNA(Lys3) (hASL(Lys3)) in order to explore the binding mechanism. By analyzing and comparing two folded conformations of this peptide obtained from the folding simulation, we found that the van der Waals (VDW) energy is necessary for the thermal stability of the peptide, and the charge-charge (ELE + EGB) energy is crucial for determining the three-dimensional folded structure of the peptide backbone. Subsequently, two conformations of the peptide were employed to investigate their binding behaviors to hASL(Lys3). The metastable folded peptide was found to bind to hASL(Lys3) much easier than the stable folded peptide in the binding simulations. An energetic analysis reveals that the VDW energy favors the binding, whereas the ELE + EGB energies disfavor the binding. Arginines on the peptide preferentially attract the phosphate backbone via the inter-chain ELE + EGB interaction, significantly contributing to the binding affinity. The hydrophobic phenylalanine interacts with the anticodon loop of hASL(Lys3) via the inter-chain VDW interaction, significantly contributing to the binding specificity.
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Affiliation(s)
- Xingqing Xiao
- a Chemical and Biomolecular Engineering Department , North Carolina State University , Engineering Building I, 911 Partners Way, Raleigh , NC 27695-7905 , USA
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50
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Hanawalt PC. The awakening of DNA repair at Yale. THE YALE JOURNAL OF BIOLOGY AND MEDICINE 2013; 86:517-23. [PMID: 24348216 PMCID: PMC3848106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
As a graduate student with Professor Richard Setlow at Yale in the late 1950s, I studied the effects of ultraviolet and visible light on the syntheses of DNA, RNA, and protein in bacteria. I reflect upon my research in the Yale Biophysics Department, my subsequent postdoctoral experiences, and the eventual analyses in the laboratories of Setlow, Paul Howard-Flanders, and myself that constituted the discovery of the ubiquitous pathway of DNA excision repair in the early 1960s. I then offer a brief perspective on a few more recent developments in the burgeoning DNA repair field and their relationships to human disease.
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