1
|
Zhao H, Li J, You Z, Lindsay HD, Yan S. Distinct regulation of ATM signaling by DNA single-strand breaks and APE1. Nat Commun 2024; 15:6517. [PMID: 39112456 PMCID: PMC11306256 DOI: 10.1038/s41467-024-50836-6] [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: 07/06/2023] [Accepted: 07/21/2024] [Indexed: 08/10/2024] Open
Abstract
In response to DNA double-strand breaks or oxidative stress, ATM-dependent DNA damage response (DDR) is activated to maintain genome integrity. However, it remains elusive whether and how DNA single-strand breaks (SSBs) activate ATM. Here, we provide direct evidence in Xenopus egg extracts that ATM-mediated DDR is activated by a defined SSB structure. Our mechanistic studies reveal that APE1 promotes the SSB-induced ATM DDR through APE1 exonuclease activity and ATM recruitment to SSB sites. APE1 protein can form oligomers to activate the ATM DDR in Xenopus egg extracts in the absence of DNA and can directly stimulate ATM kinase activity in vitro. Our findings reveal distinct mechanisms of the ATM-dependent DDR activation by SSBs in eukaryotic systems and identify APE1 as a direct activator of ATM kinase.
Collapse
Affiliation(s)
- Haichao Zhao
- Department of Biological Sciences, University of North Carolina at Charlotte, Charlotte, NC, 28223, USA
| | - Jia Li
- Department of Biological Sciences, University of North Carolina at Charlotte, Charlotte, NC, 28223, USA
| | - Zhongsheng You
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Howard D Lindsay
- Lancaster Medical School, Faculty of Health and Medicine, Lancaster University, Lancaster, LA1 4YQ, UK
| | - Shan Yan
- Department of Biological Sciences, University of North Carolina at Charlotte, Charlotte, NC, 28223, USA.
- School of Data Science, University of North Carolina at Charlotte, Charlotte, NC, 28223, USA.
- Center for Biomedical Engineering and Science, University of North Carolina at Charlotte, Charlotte, USA.
| |
Collapse
|
2
|
Alcón P, Kaczmarczyk AP, Ray KK, Liolios T, Guilbaud G, Sijacki T, Shen Y, McLaughlin SH, Sale JE, Knipscheer P, Rueda DS, Passmore LA. FANCD2-FANCI surveys DNA and recognizes double- to single-stranded junctions. Nature 2024:10.1038/s41586-024-07770-w. [PMID: 39085614 DOI: 10.1038/s41586-024-07770-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Accepted: 07/01/2024] [Indexed: 08/02/2024]
Abstract
DNA crosslinks block DNA replication and are repaired by the Fanconi anaemia pathway. The FANCD2-FANCI (D2-I) protein complex is central to this process as it initiates repair by coordinating DNA incisions around the lesion1. However, D2-I is also known to have a more general role in DNA repair and in protecting stalled replication forks from unscheduled degradation2-4. At present, it is unclear how DNA crosslinks are recognized and how D2-I functions in replication fork protection. Here, using single-molecule imaging, we show that D2-I is a sliding clamp that binds to and diffuses on double-stranded DNA. Notably, sliding D2-I stalls on encountering single-stranded-double-stranded (ss-ds) DNA junctions, structures that are generated when replication forks stall at DNA lesions5. Using cryogenic electron microscopy, we determined structures of D2-I on DNA that show that stalled D2-I makes specific interactions with the ss-dsDNA junction that are distinct from those made by sliding D2-I. Thus, D2-I surveys dsDNA and, when it reaches an ssDNA gap, it specifically clamps onto ss-dsDNA junctions. Because ss-dsDNA junctions are found at stalled replication forks, D2-I can identify sites of DNA damage. Therefore, our data provide a unified molecular mechanism that reconciles the roles of D2-I in the recognition and protection of stalled replication forks in several DNA repair pathways.
Collapse
Affiliation(s)
- Pablo Alcón
- MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Artur P Kaczmarczyk
- Department of Infectious Disease, Faculty of Medicine, Imperial College London, London, UK
- MRC Laboratory of Medical Sciences, London, UK
| | - Korak Kumar Ray
- Department of Infectious Disease, Faculty of Medicine, Imperial College London, London, UK
- MRC Laboratory of Medical Sciences, London, UK
| | - Themistoklis Liolios
- Oncode Institute, Hubrecht Institute-KNAW and University Medical Center Utrecht, Utrecht, The Netherlands
| | | | | | - Yichao Shen
- MRC Laboratory of Molecular Biology, Cambridge, UK
| | | | | | - Puck Knipscheer
- Oncode Institute, Hubrecht Institute-KNAW and University Medical Center Utrecht, Utrecht, The Netherlands
| | - David S Rueda
- Department of Infectious Disease, Faculty of Medicine, Imperial College London, London, UK.
- MRC Laboratory of Medical Sciences, London, UK.
| | | |
Collapse
|
3
|
Terui R, Berger SE, Sambel LA, Song D, Chistol G. Single-molecule imaging reveals the mechanism of bidirectional replication initiation in metazoa. Cell 2024; 187:3992-4009.e25. [PMID: 38866019 PMCID: PMC11283366 DOI: 10.1016/j.cell.2024.05.024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Revised: 03/28/2024] [Accepted: 05/13/2024] [Indexed: 06/14/2024]
Abstract
Metazoan genomes are copied bidirectionally from thousands of replication origins. Replication initiation entails the assembly and activation of two CMG helicases (Cdc45⋅Mcm2-7⋅GINS) at each origin. This requires several replication firing factors (including TopBP1, RecQL4, and DONSON) whose exact roles are still under debate. How two helicases are correctly assembled and activated at each origin is a long-standing question. By visualizing the recruitment of GINS, Cdc45, TopBP1, RecQL4, and DONSON in real time, we uncovered that replication initiation is surprisingly dynamic. First, TopBP1 transiently binds to the origin and dissociates before the start of DNA synthesis. Second, two Cdc45 are recruited together, even though Cdc45 alone cannot dimerize. Next, two copies of DONSON and two GINS simultaneously arrive at the origin, completing the assembly of two CMG helicases. Finally, RecQL4 is recruited to the CMG⋅DONSON⋅DONSON⋅CMG complex and promotes DONSON dissociation and CMG activation via its ATPase activity.
Collapse
Affiliation(s)
- Riki Terui
- Chemical and Systems Biology Department, Stanford School of Medicine, Stanford, CA 94305, USA
| | - Scott E Berger
- Biophysics Program, Stanford School of Medicine, Stanford, CA 94305, USA
| | - Larissa A Sambel
- Chemical and Systems Biology Department, Stanford School of Medicine, Stanford, CA 94305, USA
| | - Dan Song
- Chemical and Systems Biology Department, Stanford School of Medicine, Stanford, CA 94305, USA
| | - Gheorghe Chistol
- Chemical and Systems Biology Department, Stanford School of Medicine, Stanford, CA 94305, USA; Biophysics Program, Stanford School of Medicine, Stanford, CA 94305, USA; Cancer Biology Program, Stanford School of Medicine, Stanford, CA 94305, USA; Stanford Cancer Institute, Stanford School of Medicine, Stanford, CA 94305, USA; BioX Interdisciplinary Institute, Stanford School of Medicine, Stanford, CA 94305, USA.
| |
Collapse
|
4
|
Vontalge EJ, Kavlashvili T, Dahmen SN, Cranford MT, Dewar JM. Control of DNA replication in vitro using a reversible replication barrier. Nat Protoc 2024; 19:1940-1983. [PMID: 38594502 PMCID: PMC11230854 DOI: 10.1038/s41596-024-00977-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Accepted: 01/19/2024] [Indexed: 04/11/2024]
Abstract
A major obstacle to studying DNA replication is that it involves asynchronous and highly delocalized events. A reversible replication barrier overcomes this limitation and allows replication fork movement to be synchronized and localized, facilitating the study of replication fork function and replication coupled repair. Here we provide details on establishing a reversible replication barrier in vitro and using it to monitor different aspects of DNA replication. DNA template containing an array of lac operator (lacO) sequences is first bound to purified lac repressor (LacR). This substrate is then replicated in vitro using a biochemical replication system, which results in replication forks stalled on either side of the LacR array regardless of when or where they arise. Once replication forks are synchronized at the barrier, isopropyl-β-D-thiogalactopyranoside can be added to disrupt LacR binding so that replication forks synchronously resume synthesis. We describe how this approach can be employed to control replication fork elongation, termination, stalling and uncoupling, as well as assays that can be used to monitor these processes. We also explain how this approach can be adapted to control whether replication forks encounter a DNA lesion on the leading or lagging strand template and whether a converging fork is present. The required reagents can be prepared in 1-2 weeks and experiments using this approach are typically performed over 1-3 d. The main requirements for utilizing the LacR replication barrier are basic biochemical expertise and access to an in vitro system to study DNA replication. Investigators should also be trained in working with radioactive materials.
Collapse
Affiliation(s)
- Emma J Vontalge
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Tamar Kavlashvili
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Steven N Dahmen
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Matthew T Cranford
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - James M Dewar
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, USA.
| |
Collapse
|
5
|
Stillman B. Establishing a biochemical understanding of the initiation of chromosome replication in bacteria. Proc Natl Acad Sci U S A 2024; 121:e2400667121. [PMID: 38758693 PMCID: PMC11161774 DOI: 10.1073/pnas.2400667121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/19/2024] Open
Abstract
In the mid-1950s, Arthur Kornberg elucidated the enzymatic synthesis of DNA by DNA polymerase, for which he was recognized with the 1959 Nobel Prize in Physiology or Medicine. He then identified many of the proteins that cooperate with DNA polymerase to replicate duplex DNA of small bacteriophages. However, one major unanswered problem was understanding the mechanism and control of the initiation of chromosome replication in bacteria. In a seminal paper in 1981, Fuller, Kaguni, and Kornberg reported the development of a cell-free enzyme system that could replicate DNA that was dependent on the bacterial origin of DNA replication, oriC. This advance opened the door to a flurry of discoveries and important papers that elucidated the process and control of initiation of chromosome replication in bacteria.
Collapse
Affiliation(s)
- Bruce Stillman
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY11724
| |
Collapse
|
6
|
Cameron G, Gruszka D, Xie S, Kaya Ç, Nasmyth KA, Srinivasan M, Yardimci H. Sister chromatid cohesion establishment during DNA replication termination. Science 2024; 384:119-124. [PMID: 38484038 PMCID: PMC7615807 DOI: 10.1126/science.adf0224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Accepted: 02/27/2024] [Indexed: 04/06/2024]
Abstract
Newly copied sister chromatids are tethered together by the cohesin complex, but how sister chromatid cohesion coordinates with DNA replication is poorly understood. Prevailing models suggest that cohesin complexes, bound to DNA before replication, remain behind the advancing replication fork to keep sister chromatids together. By visualizing single replication forks colliding with preloaded cohesin complexes, we find that the replisome instead pushes cohesin to where a converging replisome is met. Whereas the converging replisomes are removed during DNA replication termination, cohesin remains on nascent DNA and provides cohesion. Additionally, we show that CMG (CDC45-MCM2-7-GINS) helicase disassembly during replication termination is vital for proper cohesion in budding yeast. Together, our results support a model wherein sister chromatid cohesion is established during DNA replication termination.
Collapse
Affiliation(s)
| | | | - Sherry Xie
- The Francis Crick Institute; London, United Kingdom
| | - Çağla Kaya
- The Francis Crick Institute; London, United Kingdom
| | - Kim A Nasmyth
- Department of Biochemistry, University of Oxford; Oxford, United Kingdom
| | | | | |
Collapse
|
7
|
Terui R, Berger S, Sambel L, Song D, Chistol G. Single-Molecule Imaging Reveals the Mechanism of Bidirectional Replication Initiation in Metazoa. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.28.587265. [PMID: 38585807 PMCID: PMC10996697 DOI: 10.1101/2024.03.28.587265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/09/2024]
Abstract
Metazoan genomes are copied bidirectionally from thousands of replication origins. Replication initiation entails the assembly and activation of two CMG (Cdc45•Mcm2-7•GINS) helicases at each origin. This requires several firing factors (including TopBP1, RecQL4, DONSON) whose exact roles remain unclear. How two helicases are correctly assembled and activated at every single origin is a long-standing question. By visualizing the recruitment of GINS, Cdc45, TopBP1, RecQL4, and DONSON in real time, we uncovered a surprisingly dynamic picture of initiation. Firing factors transiently bind origins but do not travel with replisomes. Two Cdc45 simultaneously arrive at each origin and two GINS are recruited together, even though neither protein can dimerize. The synchronized delivery of two GINS is mediated by DONSON, which acts as a dimerization scaffold. We show that RecQL4 promotes DONSON dissociation and facilitates helicase activation. The high fidelity of bidirectional origin firing can be explained by a Hopfield-style kinetic proofreading mechanism.
Collapse
Affiliation(s)
- Riki Terui
- Chemical and Systems Biology, Stanford School of Medicine, Stanford CA94305
| | - Scott Berger
- Biophysics Program, Stanford School of Medicine, Stanford CA94305
| | - Larissa Sambel
- Chemical and Systems Biology, Stanford School of Medicine, Stanford CA94305
| | - Dan Song
- Current Address: Eikon Therapeutics Inc
| | - Gheorghe Chistol
- Chemical and Systems Biology, Stanford School of Medicine, Stanford CA94305
- Biophysics Program, Stanford School of Medicine, Stanford CA94305
- Cancer Biology Program, Stanford School of Medicine, Stanford CA94305
- Stanford Cancer Institute, Stanford School of Medicine, Stanford CA94305
- BioX Interdisciplinary Institute, Stanford School of Medicine, Stanford CA94305
| |
Collapse
|
8
|
Chen Y, Huang JH, Phong C, Ferrell JE. Viscosity-dependent control of protein synthesis and degradation. Nat Commun 2024; 15:2149. [PMID: 38459041 PMCID: PMC10923802 DOI: 10.1038/s41467-024-46447-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2023] [Accepted: 02/28/2024] [Indexed: 03/10/2024] Open
Abstract
It has been proposed that the concentration of proteins in the cytoplasm maximizes the speed of important biochemical reactions. Here we have used Xenopus egg extracts, which can be diluted or concentrated to yield a range of cytoplasmic protein concentrations, to test the effect of cytoplasmic concentration on mRNA translation and protein degradation. We find that protein synthesis rates are maximal in ~1x cytoplasm, whereas protein degradation continues to rise to a higher optimal concentration of ~1.8x. We show that this difference in optima can be attributed to a greater sensitivity of translation to cytoplasmic viscosity. The different concentration optima could produce a negative feedback homeostatic system, where increasing the cytoplasmic protein concentration above the 1x physiological level increases the viscosity of the cytoplasm, which selectively inhibits translation and drives the system back toward the 1x set point.
Collapse
Affiliation(s)
- Yuping Chen
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA, 94305, USA.
| | - Jo-Hsi Huang
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA, 94305, USA
| | - Connie Phong
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA, 94305, USA
| | - James E Ferrell
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA, 94305, USA.
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, 94305, USA.
| |
Collapse
|
9
|
Kawasoe Y, Shimokawa S, Gillespie PJ, Blow JJ, Tsurimoto T, Takahashi TS. The Atad5 RFC-like complex is the major unloader of proliferating cell nuclear antigen in Xenopus egg extracts. J Biol Chem 2024; 300:105588. [PMID: 38141767 PMCID: PMC10827553 DOI: 10.1016/j.jbc.2023.105588] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2023] [Revised: 12/04/2023] [Accepted: 12/11/2023] [Indexed: 12/25/2023] Open
Abstract
Proliferating cell nuclear antigen (PCNA) is a homo-trimeric clamp complex that serves as the molecular hub for various DNA transactions, including DNA synthesis and post-replicative mismatch repair. Its timely loading and unloading are critical for genome stability. PCNA loading is catalyzed by Replication factor C (RFC) and the Ctf18 RFC-like complex (Ctf18-RLC), and its unloading is catalyzed by Atad5/Elg1-RLC. However, RFC, Ctf18-RLC, and even some subcomplexes of their shared subunits are capable of unloading PCNA in vitro, leaving an ambiguity in the division of labor in eukaryotic clamp dynamics. By using a system that specifically detects PCNA unloading, we show here that Atad5-RLC, which accounts for only approximately 3% of RFC/RLCs, nevertheless provides the major PCNA unloading activity in Xenopus egg extracts. RFC and Ctf18-RLC each account for approximately 40% of RFC/RLCs, while immunodepletion of neither Rfc1 nor Ctf18 detectably affects the rate of PCNA unloading in our system. PCNA unloading is dependent on the ATP-binding motif of Atad5, independent of nicks on DNA and chromatin assembly, and inhibited effectively by PCNA-interacting peptides. These results support a model in which Atad5-RLC preferentially unloads DNA-bound PCNA molecules that are free from their interactors.
Collapse
Affiliation(s)
| | - Sakiko Shimokawa
- Graduate School of Systems Life Sciences, Kyushu University, Fukuoka, Japan
| | - Peter J Gillespie
- Division of Molecular, Cell & Developmental Biology, School of Life Sciences, University of Dundee, Dundee, UK
| | - J Julian Blow
- Division of Molecular, Cell & Developmental Biology, School of Life Sciences, University of Dundee, Dundee, UK
| | | | | |
Collapse
|
10
|
Lim Y, Tamayo-Orrego L, Schmid E, Tarnauskaite Z, Kochenova OV, Gruar R, Muramatsu S, Lynch L, Schlie AV, Carroll PL, Chistol G, Reijns MAM, Kanemaki MT, Jackson AP, Walter JC. In silico protein interaction screening uncovers DONSON's role in replication initiation. Science 2023; 381:eadi3448. [PMID: 37590370 PMCID: PMC10801813 DOI: 10.1126/science.adi3448] [Citation(s) in RCA: 29] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Accepted: 08/08/2023] [Indexed: 08/19/2023]
Abstract
CDC45-MCM2-7-GINS (CMG) helicase assembly is the central event in eukaryotic replication initiation. In yeast, a multi-subunit "pre-loading complex" (pre-LC) accompanies GINS to chromatin-bound MCM2-7, leading to CMG formation. Here, we report that DONSON, a metazoan protein mutated in microcephalic primordial dwarfism, is required for CMG assembly in vertebrates. Using AlphaFold to screen for protein-protein interactions followed by experimental validation, we show that DONSON scaffolds a vertebrate pre-LC containing GINS, TOPBP1, and DNA pol ε. Our evidence suggests that DONSON docks the pre-LC onto MCM2-7, delivering GINS to its binding site in CMG. A patient-derived DONSON mutation compromises CMG assembly and recapitulates microcephalic dwarfism in mice. These results unify our understanding of eukaryotic replication initiation, implicate defective CMG assembly in microcephalic dwarfism, and illustrate how in silico protein-protein interaction screening accelerates mechanistic discovery.
Collapse
Affiliation(s)
- Yang Lim
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Blavatnik Institute; Boston, MA 02115, USA
| | - Lukas Tamayo-Orrego
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh; Edinburgh, EH4 2XU, UK
| | - Ernst Schmid
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Blavatnik Institute; Boston, MA 02115, USA
| | - Zygimante Tarnauskaite
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh; Edinburgh, EH4 2XU, UK
| | - Olga V. Kochenova
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Blavatnik Institute; Boston, MA 02115, USA
- Howard Hughes Medical Institute; Boston, MA 02115, USA
| | - Rhian Gruar
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Blavatnik Institute; Boston, MA 02115, USA
| | - Sachiko Muramatsu
- Department of Chromosome Science, National Institute of Genetics, Research Organization of Information and Systems (ROIS); Mishima, Shizuoka 411-8540, Japan
| | - Luke Lynch
- Biochemistry Department, Stanford School of Medicine; Stanford, CA 94305, USA
| | - Aitana Verdu Schlie
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh; Edinburgh, EH4 2XU, UK
| | - Paula L. Carroll
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh; Edinburgh, EH4 2XU, UK
| | - Gheorghe Chistol
- Chemical and Systems Biology Department, Stanford School of Medicine; Stanford, CA 94305, USA
| | - Martin A. M. Reijns
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh; Edinburgh, EH4 2XU, UK
| | - Masato T. Kanemaki
- Department of Chromosome Science, National Institute of Genetics, Research Organization of Information and Systems (ROIS); Mishima, Shizuoka 411-8540, Japan
- Graduate Institute for Advanced Studies, SOKENDAI; Mishima, Shizuoka 411-8540, Japan
- Department of Biological Science, The University of Tokyo; Tokyo 113-0033, Japan
| | - Andrew P. Jackson
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh; Edinburgh, EH4 2XU, UK
| | - Johannes C. Walter
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Blavatnik Institute; Boston, MA 02115, USA
- Howard Hughes Medical Institute; Boston, MA 02115, USA
| |
Collapse
|
11
|
Berger S, Chistol G. Visualizing the dynamics of DNA replication and repair at the single-molecule level. Methods Cell Biol 2023; 182:109-165. [PMID: 38359974 PMCID: PMC11246157 DOI: 10.1016/bs.mcb.2023.07.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2024]
Abstract
During cell division, the genome of each eukaryotic cell is copied by thousands of replisomes-large protein complexes consisting of several dozen proteins. Recent studies suggest that the eukaryotic replisome is much more dynamic than previously thought. To directly visualize replisome dynamics in a physiological context, we recently developed a single-molecule approach for imaging replication proteins in Xenopus egg extracts. These extracts contain all the soluble nuclear proteins and faithfully recapitulate DNA replication and repair in vitro, serving as a powerful platform for studying the mechanisms of genome maintenance. Here we present detailed protocols for conducting single-molecule experiments in nuclear egg extracts and preparing key reagents. This workflow can be easily adapted to visualize the dynamics and function of other proteins implicated in DNA replication and repair.
Collapse
Affiliation(s)
- Scott Berger
- Biophysics Program, Stanford School of Medicine, Stanford, CA, United States
| | - Gheorghe Chistol
- Biophysics Program, Stanford School of Medicine, Stanford, CA, United States; Chemical and Systems Biology Department, Cancer Biology Program, Stanford School of Medicine, Stanford, CA, United States.
| |
Collapse
|
12
|
Yaneva D, Sparks JL, Donsbach M, Zhao S, Weickert P, Bezalel-Buch R, Stingele J, Walter JC. The FANCJ helicase unfolds DNA-protein crosslinks to promote their repair. Mol Cell 2023; 83:43-56.e10. [PMID: 36608669 PMCID: PMC9881729 DOI: 10.1016/j.molcel.2022.12.005] [Citation(s) in RCA: 22] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Revised: 08/12/2022] [Accepted: 12/08/2022] [Indexed: 01/07/2023]
Abstract
Endogenous and exogenous agents generate DNA-protein crosslinks (DPCs), whose replication-dependent degradation by the SPRTN protease suppresses aging and liver cancer. SPRTN is activated after the replicative CMG helicase bypasses a DPC and polymerase extends the nascent strand to the adduct. Here, we identify a role for the 5'-to-3' helicase FANCJ in DPC repair. In addition to supporting CMG bypass, FANCJ is essential for SPRTN activation. FANCJ binds ssDNA downstream of the DPC and uses its ATPase activity to unfold the protein adduct, which exposes the underlying DNA and enables cleavage of the adduct. FANCJ-dependent DPC unfolding is also essential for translesion DNA synthesis past DPCs that cannot be degraded. In summary, our results show that helicase-mediated protein unfolding enables multiple events in DPC repair.
Collapse
Affiliation(s)
- Denitsa Yaneva
- Department of Biochemistry, Ludwig-Maximilians-University, 81377 Munich, Germany; Gene Center, Ludwig-Maximilians-University, 81377 Munich, Germany
| | - Justin L Sparks
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
| | - Maximilian Donsbach
- Department of Biochemistry, Ludwig-Maximilians-University, 81377 Munich, Germany; Gene Center, Ludwig-Maximilians-University, 81377 Munich, Germany
| | - Shubo Zhao
- Department of Biochemistry, Ludwig-Maximilians-University, 81377 Munich, Germany; Gene Center, Ludwig-Maximilians-University, 81377 Munich, Germany
| | - Pedro Weickert
- Department of Biochemistry, Ludwig-Maximilians-University, 81377 Munich, Germany; Gene Center, Ludwig-Maximilians-University, 81377 Munich, Germany
| | - Rachel Bezalel-Buch
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, Saint Louis, MO, USA
| | - Julian Stingele
- Department of Biochemistry, Ludwig-Maximilians-University, 81377 Munich, Germany; Gene Center, Ludwig-Maximilians-University, 81377 Munich, Germany.
| | - Johannes C Walter
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA; Howard Hughes Medical Institute.
| |
Collapse
|
13
|
Kavlashvili T, Liu W, Mohamed TM, Cortez D, Dewar JM. Replication fork uncoupling causes nascent strand degradation and fork reversal. Nat Struct Mol Biol 2023; 30:115-124. [PMID: 36593312 PMCID: PMC9868089 DOI: 10.1038/s41594-022-00871-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Accepted: 10/14/2022] [Indexed: 01/03/2023]
Abstract
Genotoxins cause nascent strand degradation (NSD) and fork reversal during DNA replication. NSD and fork reversal are crucial for genome stability and are exploited by chemotherapeutic approaches. However, it is unclear how NSD and fork reversal are triggered. Additionally, the fate of the replicative helicase during these processes is unknown. We developed a biochemical approach to study synchronous, localized NSD and fork reversal using Xenopus egg extracts and validated this approach with experiments in human cells. We show that replication fork uncoupling stimulates NSD of both nascent strands and progressive conversion of uncoupled forks to reversed forks. Notably, the replicative helicase remains bound during NSD and fork reversal. Unexpectedly, NSD occurs before and after fork reversal, indicating that multiple degradation steps take place. Overall, our data show that uncoupling causes NSD and fork reversal and elucidate key events that precede fork reversal.
Collapse
Affiliation(s)
- Tamar Kavlashvili
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Wenpeng Liu
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Taha M Mohamed
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - David Cortez
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - James M Dewar
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, USA.
| |
Collapse
|
14
|
Kochenova OV, Mukkavalli S, Raman M, Walter JC. Cooperative assembly of p97 complexes involved in replication termination. Nat Commun 2022; 13:6591. [PMID: 36329031 PMCID: PMC9633789 DOI: 10.1038/s41467-022-34210-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Accepted: 10/18/2022] [Indexed: 11/06/2022] Open
Abstract
The p97 ATPase extracts polyubiquitylated proteins from diverse cellular structures in preparation for destruction by the proteasome. p97 functions with Ufd1-Npl4 and a variety of UBA-UBX co-factors, but how p97 complexes assemble on ubiquitylated substrates is unclear. To address this, we investigated how p97 disassembles the CMG helicase after it is ubiquitylated during replication termination. We show that p97Ufd1-Npl4 recruitment to CMG requires the UBA-UBX protein Ubxn7, and conversely, stable Ubxn7 binding to CMG requires p97Ufd1-Npl4. This cooperative assembly involves interactions between Ubxn7, p97, Ufd1-Npl4, and ubiquitin. Another p97 co-factor, Faf1, partially compensates for the loss of Ubxn7. Surprisingly, p97Ufd1-Npl4-Ubxn7 and p97Ufd1-Npl4-Faf1 also assemble cooperatively on unanchored ubiquitin chains. We propose that cooperative and substrate-independent recognition of ubiquitin chains allows p97 to recognize an unlimited number of polyubiquitylated proteins while avoiding the formation of partial, inactive complexes.
Collapse
Affiliation(s)
- Olga V Kochenova
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Blavatnik Institute, Boston, MA, 02115, USA
- Howard Hughes Medical Institute, Boston, MA, USA
| | - Sirisha Mukkavalli
- Department of Developmental Molecular and Chemical Biology, Tufts University School of Medicine, Boston, MA, 02111, USA
| | - Malavika Raman
- Department of Developmental Molecular and Chemical Biology, Tufts University School of Medicine, Boston, MA, 02111, USA
| | - Johannes C Walter
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Blavatnik Institute, Boston, MA, 02115, USA.
- Howard Hughes Medical Institute, Boston, MA, USA.
| |
Collapse
|
15
|
Shintomi K. Making Mitotic Chromosomes in a Test Tube. EPIGENOMES 2022; 6:epigenomes6030020. [PMID: 35893016 PMCID: PMC9326633 DOI: 10.3390/epigenomes6030020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2022] [Revised: 07/18/2022] [Accepted: 07/18/2022] [Indexed: 02/01/2023] Open
Abstract
Mitotic chromosome assembly is an essential preparatory step for accurate transmission of the genome during cell division. During the past decades, biochemical approaches have uncovered the molecular basis of mitotic chromosomes. For example, by using cell-free assays of frog egg extracts, the condensin I complex central for the chromosome assembly process was first identified, and its functions have been intensively studied. A list of chromosome-associated proteins has been almost completed, and it is now possible to reconstitute structures resembling mitotic chromosomes with a limited number of purified factors. In this review, I introduce how far we have come in understanding the mechanism of chromosome assembly using cell-free assays and reconstitution assays, and I discuss their potential applications to solve open questions.
Collapse
Affiliation(s)
- Keishi Shintomi
- Chromosome Dynamics Laboratory, RIKEN, Wako 351-0198, Saitama, Japan
| |
Collapse
|
16
|
BRD4 promotes resection and homology-directed repair of DNA double-strand breaks. Nat Commun 2022; 13:3016. [PMID: 35641523 PMCID: PMC9156784 DOI: 10.1038/s41467-022-30787-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Accepted: 05/18/2022] [Indexed: 11/22/2022] Open
Abstract
Double-strand breaks (DSBs) are one of the most toxic forms of DNA damage and represent a major source of genomic instability. Members of the bromodomain and extra-terminal (BET) protein family are characterized as epigenetic readers that regulate gene expression. However, evidence suggests that BET proteins also play a more direct role in DNA repair. Here, we establish a cell-free system using Xenopus egg extracts to elucidate the gene expression-independent functions of BET proteins in DSB repair. We identify the BET protein BRD4 as a critical regulator of homologous recombination and describe its role in stimulating DNA processing through interactions with the SWI/SNF chromatin remodeling complex and resection machinery. These results establish BRD4 as a multifunctional regulator of chromatin binding that links transcriptional activity and homology-directed repair. BRD4 is a multifunctional regulator of chromatin binding that plays a direct role in DNA double-strand break repair. BRD4 interacts with the SWI/SNF chromatin remodeling complex and resection machinery to promote homologous recombination.
Collapse
|
17
|
Van Ravenstein SX, Mehta KP, Kavlashvili T, Byl JAW, Zhao R, Osheroff N, Cortez D, Dewar JM. Topoisomerase II poisons inhibit vertebrate DNA replication through distinct mechanisms. EMBO J 2022; 41:e110632. [PMID: 35578785 PMCID: PMC9194788 DOI: 10.15252/embj.2022110632] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Revised: 04/25/2022] [Accepted: 04/28/2022] [Indexed: 11/09/2022] Open
Abstract
Topoisomerase II (TOP2) unlinks chromosomes during vertebrate DNA replication. TOP2 "poisons" are widely used chemotherapeutics that stabilize TOP2 complexes on DNA, leading to cytotoxic DNA breaks. However, it is unclear how these drugs affect DNA replication, which is a major target of TOP2 poisons. Using Xenopus egg extracts, we show that the TOP2 poisons etoposide and doxorubicin both inhibit DNA replication through different mechanisms. Etoposide induces TOP2-dependent DNA breaks and TOP2-dependent fork stalling by trapping TOP2 behind replication forks. In contrast, doxorubicin does not lead to appreciable break formation and instead intercalates into parental DNA to stall replication forks independently of TOP2. In human cells, etoposide stalls forks in a TOP2-dependent manner, while doxorubicin stalls forks independently of TOP2. However, both drugs exhibit TOP2-dependent cytotoxicity. Thus, etoposide and doxorubicin inhibit DNA replication through distinct mechanisms despite shared genetic requirements for cytotoxicity.
Collapse
Affiliation(s)
| | - Kavi P Mehta
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Tamar Kavlashvili
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Jo Ann W Byl
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Runxiang Zhao
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Neil Osheroff
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, USA.,Department of Medicine (Hematology/Oncology), Vanderbilt University School of Medicine, Nashville, TN, USA
| | - David Cortez
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - James M Dewar
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, USA
| |
Collapse
|
18
|
Kavlashvili T, Dewar JM. Approaches to Monitor Termination of DNA Replication Using Xenopus Egg Extracts. Methods Mol Biol 2022; 2444:105-123. [PMID: 35290634 DOI: 10.1007/978-1-0716-2063-2_7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
DNA replication is crucial for cell viability and genome integrity. Despite its crucial role in genome duplication, the final stage of DNA replication, which is termed termination, is relatively unexplored. Our knowledge of termination is limited by cellular approaches to study DNA replication, which cannot readily detect termination. In contrast, the Xenopus laevis egg extract system allows for all of DNA replication to be readily detected. Here we describe the use of this system and assays to monitor replication termination.
Collapse
Affiliation(s)
- Tamar Kavlashvili
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - James M Dewar
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, USA.
| |
Collapse
|
19
|
Lo Furno E, Recolin B, van der Laan S, Aze A, Maiorano D. Studying the DNA damage response in embryonic systems. Methods Enzymol 2021; 661:95-120. [PMID: 34776225 DOI: 10.1016/bs.mie.2021.08.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Maintenance and surveillance of genome integrity is crucial during the very early steps of embryonic development, since de novo mutations generated during this stage can be propagated in differentiated adult cells and may lead to predisposition to diseases including cancer. Surprisingly, early embryos are characterized by a relaxed control of genome integrity, reminiscent of that observed in cancer cells. How embryos manage to produce healthy adult individuals in such conditions remains still unclear. Here, we describe protocols and methods to study and analyze the DNA damage response and genome integrity in two embryonic experimental systems, early Xenopus laevis embryos and mouse embryonic stem cells. We describe methods to study gene functions in the DNA damage response by mRNA microinjection in Xenopus embryos generated by in vitro fertilization, mutagenesis and developmental regulation of the DNA damage response. We also describe methods to analyze the DNA damage response in mESCs, including synchronization experiments that allow studying the DNA damage response at different cell cycle stages. Analysis of genome integrity in these systems may also help to shed light on the molecular mechanisms that preserve genome integrity and become dysregulated in cancer cells.
Collapse
Affiliation(s)
- Elena Lo Furno
- Institut de Génétique Humaine, Université de Montpellier, Genome Surveillance and Stability, CNRS-UMR9002, Montpellier, France
| | - Bénédicte Recolin
- Institut de Génétique Humaine, Université de Montpellier, Genome Surveillance and Stability, CNRS-UMR9002, Montpellier, France.
| | - Siem van der Laan
- Institut de Génétique Humaine, Université de Montpellier, Genome Surveillance and Stability, CNRS-UMR9002, Montpellier, France
| | - Antoine Aze
- Institut de Génétique Humaine, Université de Montpellier, Genome Surveillance and Stability, CNRS-UMR9002, Montpellier, France
| | - Domenico Maiorano
- Institut de Génétique Humaine, Université de Montpellier, Genome Surveillance and Stability, CNRS-UMR9002, Montpellier, France.
| |
Collapse
|
20
|
Fuchs RP, Isogawa A, Paulo JA, Onizuka K, Takahashi T, Amunugama R, Duxin JP, Fujii S. Crosstalk between repair pathways elicits double-strand breaks in alkylated DNA and implications for the action of temozolomide. eLife 2021; 10:e69544. [PMID: 34236314 PMCID: PMC8289412 DOI: 10.7554/elife.69544] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Accepted: 07/07/2021] [Indexed: 12/12/2022] Open
Abstract
Temozolomide (TMZ), a DNA methylating agent, is the primary chemotherapeutic drug used in glioblastoma treatment. TMZ induces mostly N-alkylation adducts (N7-methylguanine and N3-methyladenine) and some O6-methylguanine (O6mG) adducts. Current models propose that during DNA replication, thymine is incorporated across from O6mG, promoting a futile cycle of mismatch repair (MMR) that leads to DNA double-strand breaks (DSBs). To revisit the mechanism of O6mG processing, we reacted plasmid DNA with N-methyl-N-nitrosourea (MNU), a temozolomide mimic, and incubated it in Xenopus egg-derived extracts. We have shown that in this system, MMR proteins are enriched on MNU-treated DNA and we observed robust, MMR-dependent, repair synthesis. Our evidence also suggests that MMR, initiated at O6mG:C sites, is strongly stimulated in cis by repair processing of other lesions, such as N-alkylation adducts. Importantly, MNU-treated plasmids display DSBs in extracts, the frequency of which increases linearly with the square of alkylation dose. We suggest that DSBs result from two independent repair processes, one involving MMR at O6mG:C sites and the other involving base excision repair acting at a nearby N-alkylation adduct. We propose a new, replication-independent mechanism of action of TMZ, which operates in addition to the well-studied cell cycle-dependent mode of action.
Collapse
Affiliation(s)
- Robert P Fuchs
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical SchoolBostonUnited States
| | - Asako Isogawa
- Cancer Research Center of Marseille, UMR7258, CNRSMarseilleFrance
| | - Joao A Paulo
- Department of Cell Biology, Harvard Medical SchoolBostonUnited States
| | - Kazumitsu Onizuka
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku UniversitySendaiJapan
| | | | - Ravindra Amunugama
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical SchoolBostonUnited States
| | - Julien P Duxin
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical SchoolBostonUnited States
| | - Shingo Fujii
- Cancer Research Center of Marseille, UMR7258, CNRSMarseilleFrance
| |
Collapse
|
21
|
Barrows JK, Fullbright G, Long D. BRCA1-BARD1 regulates transcription through BRD4 in Xenopus nucleoplasmic extract. Nucleic Acids Res 2021; 49:3263-3273. [PMID: 33660782 PMCID: PMC8034626 DOI: 10.1093/nar/gkab111] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Revised: 02/03/2021] [Accepted: 02/08/2021] [Indexed: 12/19/2022] Open
Abstract
The tumor suppressor BRCA1 is considered a master regulator of genome integrity. Although widely recognized for its DNA repair functions, BRCA1 has also been implicated in various mechanisms of chromatin remodeling and transcription regulation. However, the precise role that BRCA1 plays in these processes has been difficult to establish due to the widespread consequences of its cellular dysfunction. Here, we use nucleoplasmic extract derived from the eggs of Xenopus laevis to investigate the role of BRCA1 in a cell-free transcription system. We report that BRCA1-BARD1 suppresses transcription initiation independent of DNA damage signaling and its established role in histone H2A ubiquitination. BRCA1-BARD1 acts through a histone intermediate, altering acetylation of histone H4K8 and recruitment of the chromatin reader and oncogene regulator BRD4. Together, these results establish a functional relationship between an established (BRCA1) and emerging (BRD4) regulator of genome integrity.
Collapse
Affiliation(s)
- John K Barrows
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC 29425, USA
| | - George Fullbright
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC 29425, USA
| | - David T Long
- To whom correspondence should be addressed. Tel: +1 843 792 6949;
| |
Collapse
|
22
|
Kumagai A, Dunphy WG. Binding of the Treslin-MTBP Complex to Specific Regions of the Human Genome Promotes the Initiation of DNA Replication. Cell Rep 2021; 32:108178. [PMID: 32966791 PMCID: PMC7523632 DOI: 10.1016/j.celrep.2020.108178] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Revised: 06/12/2020] [Accepted: 08/31/2020] [Indexed: 12/16/2022] Open
Abstract
The processes that control where higher eukaryotic cells initiate DNA replication throughout the genome are not understood clearly. In metazoans, the Treslin-MTBP complex mediates critical final steps in formation of the activated replicative helicase prior to initiation of replication. Here, we map the genome-wide distribution of the MTBP subunit of this complex in human cells. Our results indicate that MTBP binds to at least 30,000 sites in the genome. A majority of these sites reside in regions of open chromatin that contain transcriptional-regulatory elements (e.g., promoters, enhancers, and super-enhancers), which are known to be preferred areas for initiation of replication. Furthermore, many binding sites encompass two genomic features: a nucleosome-free DNA sequence (e.g., G-quadruplex DNA or AP-1 motif) and a nucleosome bearing histone marks characteristic of open chromatin, such as H3K4me2. Taken together, these findings indicate that Treslin-MTBP associates coordinately with multiple genomic signals to promote initiation of replication. Kumagai and Dunphy show that Treslin-MTBP, activator of the replicative helicase, binds to at least 30,000 sites in the human genome. Many sites contain a nucleosome with active chromatin marks and nucleosome-free DNA (G-quadruplex or AP-1 site). Thus, Treslin-MTBP associates with multiple genomic elements to promote initiation of DNA replication.
Collapse
Affiliation(s)
- Akiko Kumagai
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - William G Dunphy
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA.
| |
Collapse
|
23
|
Studying chromosome biology with single-molecule resolution in Xenopus laevis egg extracts. Essays Biochem 2021; 65:17-26. [PMID: 33438722 PMCID: PMC8056035 DOI: 10.1042/ebc20200026] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2020] [Revised: 11/16/2020] [Accepted: 11/25/2020] [Indexed: 01/11/2023]
Abstract
Cell-free extracts from Xenopus laevis eggs are a model system for studying chromosome biology. Xenopus egg extracts can be synchronised in different cell cycle stages, making them useful for studying DNA replication, DNA repair and chromosome organisation. Combining single-molecule approaches with egg extracts is an exciting development being used to reveal molecular mechanisms that are difficult to study using conventional approaches. Fluorescence-based single-molecule imaging of surface-tethered DNAs has been used to visualise labelled protein movements on stretched DNA, the dynamics of DNA–protein complexes and extract-dependent structural rearrangement of stained DNA. Force-based single-molecule techniques are an alternative approach to measure mechanics of DNA and proteins. In this essay, the details of these single-molecule techniques, and the insights into chromosome biology they provide, will be discussed.
Collapse
|
24
|
Vrtis KB, Dewar JM, Chistol G, Wu RA, Graham TGW, Walter JC. Single-strand DNA breaks cause replisome disassembly. Mol Cell 2021; 81:1309-1318.e6. [PMID: 33484638 DOI: 10.1016/j.molcel.2020.12.039] [Citation(s) in RCA: 49] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2020] [Revised: 12/11/2020] [Accepted: 12/23/2020] [Indexed: 11/16/2022]
Abstract
DNA damage impedes replication fork progression and threatens genome stability. Upon encounter with most DNA adducts, the replicative CMG helicase (CDC45-MCM2-7-GINS) stalls or uncouples from the point of synthesis, yet eventually resumes replication. However, little is known about the effect on replication of single-strand breaks or "nicks," which are abundant in mammalian cells. Using Xenopus egg extracts, we reveal that CMG collision with a nick in the leading strand template generates a blunt-ended double-strand break (DSB). Moreover, CMG, which encircles the leading strand template, "runs off" the end of the DSB. In contrast, CMG collision with a lagging strand nick generates a broken end with a single-stranded overhang. In this setting, CMG translocates along double-stranded DNA beyond the break and is then ubiquitylated and removed from chromatin by the same pathway used during replication termination. Our results show that nicks are uniquely dangerous DNA lesions that invariably cause replisome disassembly, and they suggest that CMG cannot be stored on dsDNA while cells resolve replication stress.
Collapse
Affiliation(s)
- Kyle B Vrtis
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Blavatnik Institute, Boston, MA 02115, USA
| | - James M Dewar
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Blavatnik Institute, Boston, MA 02115, USA
| | - Gheorghe Chistol
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Blavatnik Institute, Boston, MA 02115, USA
| | - R Alex Wu
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Blavatnik Institute, Boston, MA 02115, USA
| | - Thomas G W Graham
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Blavatnik Institute, Boston, MA 02115, USA
| | - Johannes C Walter
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Blavatnik Institute, Boston, MA 02115, USA; Howard Hughes Medical Institute, Boston, MA 02115, USA.
| |
Collapse
|
25
|
Hashimoto Y, Tanaka H. Ongoing replication forks delay the nuclear envelope breakdown upon mitotic entry. J Biol Chem 2021; 296:100033. [PMID: 33148697 PMCID: PMC7948514 DOI: 10.1074/jbc.ra120.015142] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Revised: 11/02/2020] [Accepted: 11/04/2020] [Indexed: 01/22/2023] Open
Abstract
DNA replication is a major contributor to genomic instability, and protection against DNA replication perturbation is essential for normal cell division. Certain types of replication stress agents, such as aphidicolin and hydroxyurea, have been shown to cause reversible replication fork stalling, wherein replisome complexes are stably maintained with competence to restart in the S phase of the cell cycle. If these stalled forks persist into the M phase without a replication restart, replisomes are disassembled in a p97-dependent pathway and under-replicated DNA is subjected to mitotic DNA repair synthesis. Here, using Xenopus egg extracts, we investigated the consequences that arise when stalled forks are released simultaneously with the induction of mitosis. Ara-cytidine-5'-triphosphate-induced stalled forks were able to restart with the addition of excess dCTP during early mitosis before the nuclear envelope breakdown (NEB). However, stalled forks could no longer restart efficiently after the NEB. Although replisome complexes were finally disassembled in a p97-dependent manner during mitotic progression whether or not fork stalling was relieved, the timing of the NEB was delayed with the ongoing forks, rather than the stalled forks, and the delay was dependent on Wee1/Myt1 kinase activities. Thus, ongoing DNA replication was found to be directly linked to the regulation of Wee1/Myt1 kinases to modulate cyclin-dependent kinase activities because of which DNA replication and mitosis occur in a mutually exclusive and sequential manner.
Collapse
Affiliation(s)
- Yoshitami Hashimoto
- School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo, Japan.
| | - Hirofumi Tanaka
- School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo, Japan
| |
Collapse
|
26
|
Abstract
The DNA damage response (DDR) is a coordinated cellular response to a variety of insults to the genome. DDR initiates the activation of cell cycle checkpoints preventing the propagation of damaged DNA followed by DNA repair, which are both critical in maintaining genome integrity. Several model systems have been developed to study the mechanisms and complexity of checkpoint function. Here we describe the application of cell-free extracts derived from Xenopus eggs as a model system to investigate signaling from DNA damage, modulation of DNA replication, checkpoint activation, and ultimately DNA repair. We outline the preparation of cell-free extracts, DNA substrates, and their subsequent use in assays aimed at understanding the cellular response to DNA damage. Cell-free extracts derived from the eggs of Xenopus laevis remain a robust and versatile system to decipher the biochemical steps underlying this essential characteristic of all cells, critical for genome stability.
Collapse
|
27
|
Heintzman DR, Campos LV, Byl JAW, Osheroff N, Dewar JM. Topoisomerase II Is Crucial for Fork Convergence during Vertebrate Replication Termination. Cell Rep 2020; 29:422-436.e5. [PMID: 31597101 PMCID: PMC6919565 DOI: 10.1016/j.celrep.2019.08.097] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Revised: 07/27/2019] [Accepted: 08/28/2019] [Indexed: 11/28/2022] Open
Abstract
Termination of DNA replication occurs when two replication forks converge upon the same stretch of DNA. Resolution of topological stress by topoisomerases is crucial for fork convergence in bacteria and viruses, but it is unclear whether similar mechanisms operate during vertebrate termination. Using Xenopus egg extracts, we show that topoisomerase II (Top2) resolves topological stress to prevent converging forks from stalling during termination. Under these conditions, stalling arises due to an inability to unwind the final stretch of DNA ahead of each fork. By promoting fork convergence, Top2 facilitates all downstream events of termination. Converging forks ultimately overcome stalling independently of Top2, indicating that additional mechanisms support fork convergence. Top2 acts throughout replication to prevent the accumulation of topological stress that would otherwise stall converging forks. Thus, termination poses evolutionarily conserved topological problems that can be mitigated by careful execution of the earlier stages of replication.
Collapse
Affiliation(s)
- Darren R Heintzman
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Lillian V Campos
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Jo Ann W Byl
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Neil Osheroff
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; Department of Medicine (Hematology, Oncology), Vanderbilt University School of Medicine, Nashville, TN 37232, USA; VA Tennessee Valley Healthcare System, Nashville, TN 37212, USA
| | - James M Dewar
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232, USA.
| |
Collapse
|
28
|
Rogers CM, Simmons Iii RH, Fluhler Thornburg GE, Buehler NJ, Bochman ML. Fanconi anemia-independent DNA inter-strand crosslink repair in eukaryotes. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2020; 158:33-46. [PMID: 32877700 DOI: 10.1016/j.pbiomolbio.2020.08.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Accepted: 08/21/2020] [Indexed: 02/07/2023]
Abstract
DNA inter-strand crosslinks (ICLs) are dangerous lesions that can be caused by a variety of endogenous and exogenous bifunctional compounds. Because covalently linking both strands of the double helix locally disrupts DNA replication and transcription, failure to remove even a single ICL can be fatal to the cell. Thus, multiple ICL repair pathways have evolved, with the best studied being the canonical Fanconi anemia (FA) pathway. However, recent research demonstrates that different types of ICLs (e.g., backbone distorting vs. non-distorting) can be discriminated by the cell, which then mounts a specific repair response using the FA pathway or one of a variety of FA-independent ICL repair pathways. This review focuses on the latter, covering current work on the transcription-coupled, base excision, acetaldehyde-induced, and SNM1A/RecQ4 ICL repair pathways and highlighting unanswered questions in the field. Answering these questions will provide mechanistic insight into the various pathways of ICL repair and enable ICL-inducing agents to be more effectively used as chemotherapeutics.
Collapse
Affiliation(s)
- Cody M Rogers
- Molecular and Cellular Biochemistry Department, Indiana University, 212 S. Hawthorne Dr., Simon Hall MSB1 room 405B, Bloomington, IN, 47405, USA
| | - Robert H Simmons Iii
- Molecular and Cellular Biochemistry Department, Indiana University, 212 S. Hawthorne Dr., Simon Hall MSB1 room 405B, Bloomington, IN, 47405, USA
| | - Gabriella E Fluhler Thornburg
- Molecular and Cellular Biochemistry Department, Indiana University, 212 S. Hawthorne Dr., Simon Hall MSB1 room 405B, Bloomington, IN, 47405, USA
| | - Nicholas J Buehler
- Molecular and Cellular Biochemistry Department, Indiana University, 212 S. Hawthorne Dr., Simon Hall MSB1 room 405B, Bloomington, IN, 47405, USA
| | - Matthew L Bochman
- Molecular and Cellular Biochemistry Department, Indiana University, 212 S. Hawthorne Dr., Simon Hall MSB1 room 405B, Bloomington, IN, 47405, USA.
| |
Collapse
|
29
|
Joseph SA, Taglialatela A, Leuzzi G, Huang JW, Cuella-Martin R, Ciccia A. Time for remodeling: SNF2-family DNA translocases in replication fork metabolism and human disease. DNA Repair (Amst) 2020; 95:102943. [PMID: 32971328 DOI: 10.1016/j.dnarep.2020.102943] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2020] [Revised: 07/24/2020] [Accepted: 07/26/2020] [Indexed: 02/07/2023]
Abstract
Over the course of DNA replication, DNA lesions, transcriptional intermediates and protein-DNA complexes can impair the progression of replication forks, thus resulting in replication stress. Failure to maintain replication fork integrity in response to replication stress leads to genomic instability and predisposes to the development of cancer and other genetic disorders. Multiple DNA damage and repair pathways have evolved to allow completion of DNA replication following replication stress, thus preserving genomic integrity. One of the processes commonly induced in response to replication stress is fork reversal, which consists in the remodeling of stalled replication forks into four-way DNA junctions. In normal conditions, fork reversal slows down replication fork progression to ensure accurate repair of DNA lesions and facilitates replication fork restart once the DNA lesions have been removed. However, in certain pathological situations, such as the deficiency of DNA repair factors that protect regressed forks from nuclease-mediated degradation, fork reversal can cause genomic instability. In this review, we describe the complex molecular mechanisms regulating fork reversal, with a focus on the role of the SNF2-family fork remodelers SMARCAL1, ZRANB3 and HLTF, and highlight the implications of fork reversal for tumorigenesis and cancer therapy.
Collapse
Affiliation(s)
- Sarah A Joseph
- Department of Genetics and Development, Herbert Irving Comprehensive Cancer Center, Columbia University Irving Medical Center, New York, NY, USA
| | - Angelo Taglialatela
- Department of Genetics and Development, Herbert Irving Comprehensive Cancer Center, Columbia University Irving Medical Center, New York, NY, USA
| | - Giuseppe Leuzzi
- Department of Genetics and Development, Herbert Irving Comprehensive Cancer Center, Columbia University Irving Medical Center, New York, NY, USA
| | - Jen-Wei Huang
- Department of Genetics and Development, Herbert Irving Comprehensive Cancer Center, Columbia University Irving Medical Center, New York, NY, USA
| | - Raquel Cuella-Martin
- Department of Genetics and Development, Herbert Irving Comprehensive Cancer Center, Columbia University Irving Medical Center, New York, NY, USA
| | - Alberto Ciccia
- Department of Genetics and Development, Herbert Irving Comprehensive Cancer Center, Columbia University Irving Medical Center, New York, NY, USA.
| |
Collapse
|
30
|
Distinct roles of XRCC1 in genome integrity in Xenopus egg extracts. Biochem J 2020; 476:3791-3804. [PMID: 31808793 DOI: 10.1042/bcj20190798] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 12/04/2019] [Accepted: 12/06/2019] [Indexed: 02/06/2023]
Abstract
Oxidative DNA damage represents one of the most abundant DNA lesions. It remains unclear how DNA repair and DNA damage response (DDR) pathways are co-ordinated and regulated following oxidative stress. While XRCC1 has been implicated in DNA repair, it remains unknown how exactly oxidative DNA damage is repaired and sensed by XRCC1. In this communication, we have demonstrated evidence that XRCC1 is dispensable for ATR-Chk1 DDR pathway following oxidative stress in Xenopus egg extracts. Whereas APE2 is essential for SSB repair, XRCC1 is not required for the repair of defined SSB and gapped plasmids with a 5'-OH or 5'-P terminus, suggesting that XRCC1 and APE2 may contribute to SSB repair via different mechanisms. Neither Polymerase beta nor Polymerase alpha is important for the repair of defined SSB structure. Nonetheless, XRCC1 is important for the repair of DNA damage following oxidative stress. Our observations suggest distinct roles of XRCC1 for genome integrity in oxidative stress in Xenopus egg extracts.
Collapse
|
31
|
Sato K, Brandsma I, van Rossum-Fikkert SE, Verkaik N, Oostra AB, Dorsman JC, van Gent DC, Knipscheer P, Kanaar R, Zelensky AN. HSF2BP negatively regulates homologous recombination in DNA interstrand crosslink repair. Nucleic Acids Res 2020; 48:2442-2456. [PMID: 31960047 PMCID: PMC7049687 DOI: 10.1093/nar/gkz1219] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Revised: 12/16/2019] [Accepted: 12/20/2019] [Indexed: 02/06/2023] Open
Abstract
The tumor suppressor BRCA2 is essential for homologous recombination (HR), replication fork stability and DNA interstrand crosslink (ICL) repair in vertebrates. We show that ectopic production of HSF2BP, a BRCA2-interacting protein required for meiotic HR during mouse spermatogenesis, in non-germline human cells acutely sensitize them to ICL-inducing agents (mitomycin C and cisplatin) and PARP inhibitors, resulting in a phenotype characteristic of cells from Fanconi anemia (FA) patients. We biochemically recapitulate the suppression of ICL repair and establish that excess HSF2BP compromises HR by triggering the removal of BRCA2 from the ICL site and thereby preventing the loading of RAD51. This establishes ectopic expression of a wild-type meiotic protein in the absence of any other protein-coding mutations as a new mechanism that can lead to an FA-like cellular phenotype. Naturally occurring elevated production of HSF2BP in tumors may be a source of cancer-promoting genomic instability and also a targetable vulnerability.
Collapse
Affiliation(s)
- Koichi Sato
- Oncode Institute, Hubrecht Institute-KNAW and University Medical Center Utrecht, 3584 CT Utrecht, The Netherlands
| | - Inger Brandsma
- Department of Molecular Genetics, Oncode Institute, Erasmus University Medical Center, 3000 CA Rotterdam, The Netherlands
| | - Sari E van Rossum-Fikkert
- Department of Molecular Genetics, Oncode Institute, Erasmus University Medical Center, 3000 CA Rotterdam, The Netherlands
| | - Nicole Verkaik
- Department of Molecular Genetics, Oncode Institute, Erasmus University Medical Center, 3000 CA Rotterdam, The Netherlands
| | - Anneke B Oostra
- Department of Clinical Genetics, VU University Medical Center, Van der Boechorststraat 7, 1081 BT Amsterdam, The Netherlands
| | - Josephine C Dorsman
- Department of Clinical Genetics, VU University Medical Center, Van der Boechorststraat 7, 1081 BT Amsterdam, The Netherlands
| | - Dik C van Gent
- Department of Molecular Genetics, Oncode Institute, Erasmus University Medical Center, 3000 CA Rotterdam, The Netherlands
| | - Puck Knipscheer
- Oncode Institute, Hubrecht Institute-KNAW and University Medical Center Utrecht, 3584 CT Utrecht, The Netherlands
| | - Roland Kanaar
- Department of Molecular Genetics, Oncode Institute, Erasmus University Medical Center, 3000 CA Rotterdam, The Netherlands
| | - Alex N Zelensky
- Department of Molecular Genetics, Oncode Institute, Erasmus University Medical Center, 3000 CA Rotterdam, The Netherlands
| |
Collapse
|
32
|
|
33
|
Barrows JK, Long DT. Cell-free transcription in Xenopus egg extract. J Biol Chem 2019; 294:19645-19654. [PMID: 31732562 DOI: 10.1074/jbc.ra119.011350] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Revised: 11/05/2019] [Indexed: 01/08/2023] Open
Abstract
Soluble extracts prepared from Xenopus eggs have been used extensively to study various aspects of cellular and developmental biology. During early egg development, transcription of the zygotic genome is suppressed. As a result, traditional extracts derived from unfertilized and early stage eggs possess little or no intrinsic transcriptional activity. In this study, we show that Xenopus nucleoplasmic extract (NPE) supports robust transcription of a chromatinized plasmid substrate. Although prepared from eggs in a transcriptionally inactive state, the process of making NPE resembles some aspects of egg fertilization and early embryo development that lead to transcriptional activation. With this system, we observed that promoter-dependent recruitment of transcription factors and RNA polymerase II leads to conventional patterns of divergent transcription and pre-mRNA processing, including intron splicing and 3' cleavage and polyadenylation. We also show that histone density controls transcription factor binding and RNA polymerase II activity, validating a mechanism proposed to regulate genome activation during development. Together, these results establish a new cell-free system to study the regulation, initiation, and processing of mRNA transcripts.
Collapse
Affiliation(s)
- John K Barrows
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, South Carolina
| | - David T Long
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, South Carolina
| |
Collapse
|
34
|
Hoogenboom WS, Boonen RACM, Knipscheer P. The role of SLX4 and its associated nucleases in DNA interstrand crosslink repair. Nucleic Acids Res 2019; 47:2377-2388. [PMID: 30576517 PMCID: PMC6411836 DOI: 10.1093/nar/gky1276] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Revised: 12/11/2018] [Accepted: 12/13/2018] [Indexed: 12/11/2022] Open
Abstract
A key step in the Fanconi anemia pathway of DNA interstrand crosslink (ICL) repair is the ICL unhooking by dual endonucleolytic incisions. SLX4/FANCP is a large scaffold protein that plays a central role in ICL unhooking. It contains multiple domains that interact with many proteins including three different endonucleases and also acts in several other DNA repair pathways. While it is known that its interaction with the endonuclease XPF-ERCC1 is required for its function in ICL repair, which other domains act in this process is unclear. Here, we used Xenopus egg extracts to determine ICL repair specific features of SLX4. We show that the SLX4-interacting endonuclease SLX1 is not required for ICL repair and demonstrate that all essential SLX4 domains are located at the N-terminal half of the protein. The MLR domain is crucial for the recruitment of XPF-ERCC1 but also has an unanticipated function in recruiting SLX4 to the site of damage. Although we find the BTB is not essential for ICL repair in our system, dimerization of SLX4 could be important. Our data provide new insights into the mechanism by which SLX4 acts in ICL repair.
Collapse
Affiliation(s)
- Wouter S Hoogenboom
- Oncode Institute, Hubrecht Institute-KNAW and University Medical Center Utrecht, Utrecht, The Netherlands
| | - Rick A C M Boonen
- Oncode Institute, Hubrecht Institute-KNAW and University Medical Center Utrecht, Utrecht, The Netherlands
| | - Puck Knipscheer
- Oncode Institute, Hubrecht Institute-KNAW and University Medical Center Utrecht, Utrecht, The Netherlands
| |
Collapse
|
35
|
Rycenga HB, Wolfe KB, Yeh ES, Long DT. Uncoupling of p97 ATPase activity has a dominant negative effect on protein extraction. Sci Rep 2019; 9:10329. [PMID: 31316150 PMCID: PMC6637110 DOI: 10.1038/s41598-019-46949-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Accepted: 07/04/2019] [Indexed: 12/13/2022] Open
Abstract
p97 is a highly abundant, homohexameric AAA+ ATPase that performs a variety of essential cellular functions. Characterized as a ubiquitin-selective chaperone, p97 recognizes proteins conjugated to K48-linked polyubiquitin chains and promotes their removal from chromatin and other molecular complexes. Changes in p97 expression or activity are associated with the development of cancer and several related neurodegenerative disorders. Although pathogenic p97 mutations cluster in and around p97’s ATPase domains, mutant proteins display normal or elevated ATPase activity. Here, we show that one of the most common p97 mutations (R155C) retains ATPase activity, but is functionally defective. p97-R155C can be recruited to ubiquitinated substrates on chromatin, but is unable to promote substrate removal. As a result, p97-R155C acts as a dominant negative, blocking protein extraction by a similar mechanism to that observed when p97’s ATPase activity is inhibited or inactivated. However, unlike ATPase-deficient proteins, p97-R155C consumes excess ATP, which can hinder high-energy processes. Together, our results shed new insight into how pathogenic mutations in p97 alter its cellular function, with implications for understanding the etiology and treatment of p97-associated diseases.
Collapse
Affiliation(s)
- Halley B Rycenga
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC, 29425, USA
| | - Kelly B Wolfe
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC, 29425, USA
| | - Elizabeth S Yeh
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - David T Long
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC, 29425, USA.
| |
Collapse
|
36
|
Lin Y, Bai L, Cupello S, Hossain MA, Deem B, McLeod M, Raj J, Yan S. APE2 promotes DNA damage response pathway from a single-strand break. Nucleic Acids Res 2019; 46:2479-2494. [PMID: 29361157 PMCID: PMC5861430 DOI: 10.1093/nar/gky020] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Accepted: 01/09/2018] [Indexed: 02/06/2023] Open
Abstract
As the most common type of DNA damage, DNA single-strand breaks (SSBs) are primarily repaired by the SSB repair mechanism. If not repaired properly or promptly, unrepaired SSBs lead to genome stability and have been implicated in cancer and neurodegenerative diseases. However, it remains unknown how unrepaired SSBs are recognized by DNA damage response (DDR) pathway, largely because of the lack of a feasible experimental system. Here, we demonstrate evidence showing that an ATR-dependent checkpoint signaling is activated by a defined plasmid-based site-specific SSB structure in Xenopus HSS (high-speed supernatant) system. Notably, the distinct SSB signaling requires APE2 and canonical checkpoint proteins, including ATR, ATRIP, TopBP1, Rad9 and Claspin. Importantly, the SSB-induced ATR DDR is essential for SSB repair. We and others show that APE2 interacts with PCNA via its PIP box and preferentially interacts with ssDNA via its C-terminus Zf–GRF domain, a conserved motif found in >100 proteins involved in DNA/RNA metabolism. Here, we identify a novel mode of APE2–PCNA interaction via APE2 Zf–GRF and PCNA C-terminus. Mechanistically, the APE2 Zf–GRF–PCNA interaction facilitates 3′-5′ SSB end resection, checkpoint protein complex assembly, and SSB-induced DDR pathway. Together, we propose that APE2 promotes ATR–Chk1 DDR pathway from a single-strand break.
Collapse
Affiliation(s)
- Yunfeng Lin
- Department of Biological Sciences, University of North Carolina at Charlotte, Charlotte, NC 28223, USA
| | - Liping Bai
- Department of Biological Sciences, University of North Carolina at Charlotte, Charlotte, NC 28223, USA
| | - Steven Cupello
- Department of Biological Sciences, University of North Carolina at Charlotte, Charlotte, NC 28223, USA
| | - Md Akram Hossain
- Department of Biological Sciences, University of North Carolina at Charlotte, Charlotte, NC 28223, USA
| | - Bradley Deem
- Department of Biological Sciences, University of North Carolina at Charlotte, Charlotte, NC 28223, USA
| | - Melissa McLeod
- Department of Biological Sciences, University of North Carolina at Charlotte, Charlotte, NC 28223, USA
| | - Jude Raj
- Department of Biological Sciences, University of North Carolina at Charlotte, Charlotte, NC 28223, USA
| | - Shan Yan
- Department of Biological Sciences, University of North Carolina at Charlotte, Charlotte, NC 28223, USA
| |
Collapse
|
37
|
Deng L, Wu RA, Sonneville R, Kochenova OV, Labib K, Pellman D, Walter JC. Mitotic CDK Promotes Replisome Disassembly, Fork Breakage, and Complex DNA Rearrangements. Mol Cell 2019; 73:915-929.e6. [PMID: 30849395 PMCID: PMC6410736 DOI: 10.1016/j.molcel.2018.12.021] [Citation(s) in RCA: 92] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2018] [Revised: 10/03/2018] [Accepted: 12/21/2018] [Indexed: 12/27/2022]
Abstract
DNA replication errors generate complex chromosomal rearrangements and thereby contribute to tumorigenesis and other human diseases. One mechanism that triggers these errors is mitotic entry before the completion of DNA replication. To address how mitosis might affect DNA replication, we used Xenopus egg extracts. When mitotic CDK (Cyclin B1-CDK1) is used to drive interphase egg extracts into a mitotic state, the replicative CMG (CDC45/MCM2-7/GINS) helicase undergoes ubiquitylation on its MCM7 subunit, dependent on the E3 ubiquitin ligase TRAIP. Whether replisomes have stalled or undergone termination, CMG ubiquitylation is followed by its extraction from chromatin by the CDC48/p97 ATPase. TRAIP-dependent CMG unloading during mitosis is also seen in C. elegans early embryos. At stalled forks, CMG removal results in fork breakage and end joining events involving deletions and templated insertions. Our results identify a mitotic pathway of global replisome disassembly that can trigger replication fork collapse and DNA rearrangements.
Collapse
Affiliation(s)
- Lin Deng
- Department of Pediatric Oncology, Dana-Farber Cancer Institute, Boston, MA 02215, USA; Department of Cell Biology, Harvard Medical School, Blavatnik Institute, Boston, MA 02115, USA; Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Blavatnik Institute, Boston, MA 02115, USA
| | - R Alex Wu
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Blavatnik Institute, Boston, MA 02115, USA
| | - Remi Sonneville
- MRC Protein Phosphorylation and Ubiquitylation Unit, Sir James Black Centre, School of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, UK
| | - Olga V Kochenova
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Blavatnik Institute, Boston, MA 02115, USA
| | - Karim Labib
- MRC Protein Phosphorylation and Ubiquitylation Unit, Sir James Black Centre, School of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, UK
| | - David Pellman
- Department of Pediatric Oncology, Dana-Farber Cancer Institute, Boston, MA 02215, USA; Department of Cell Biology, Harvard Medical School, Blavatnik Institute, Boston, MA 02115, USA; Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Howard Hughes Medical Institute, Boston, MA 02115, USA.
| | - Johannes C Walter
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Blavatnik Institute, Boston, MA 02115, USA; Howard Hughes Medical Institute, Boston, MA 02115, USA.
| |
Collapse
|
38
|
Wu RA, Semlow DR, Kamimae-Lanning AN, Kochenova OV, Chistol G, Hodskinson MR, Amunugama R, Sparks JL, Wang M, Deng L, Mimoso CA, Low E, Patel KJ, Walter JC. TRAIP is a master regulator of DNA interstrand crosslink repair. Nature 2019; 567:267-272. [PMID: 30842657 PMCID: PMC6417926 DOI: 10.1038/s41586-019-1002-0] [Citation(s) in RCA: 114] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Accepted: 02/01/2019] [Indexed: 12/24/2022]
Abstract
Cells often use multiple pathways to repair the same DNA lesion, and the choice of pathway has substantial implications for the fidelity of genome maintenance. DNA interstrand crosslinks covalently link the two strands of DNA, and thereby block replication and transcription; the cytotoxicity of these crosslinks is exploited for chemotherapy. In Xenopus egg extracts, the collision of replication forks with interstrand crosslinks initiates two distinct repair pathways. NEIL3 glycosylase can cleave the crosslink1; however, if this fails, Fanconi anaemia proteins incise the phosphodiester backbone that surrounds the interstrand crosslink, generating a double-strand-break intermediate that is repaired by homologous recombination2. It is not known how the simpler NEIL3 pathway is prioritized over the Fanconi anaemia pathway, which can cause genomic rearrangements. Here we show that the E3 ubiquitin ligase TRAIP is required for both pathways. When two replisomes converge at an interstrand crosslink, TRAIP ubiquitylates the replicative DNA helicase CMG (the complex of CDC45, MCM2-7 and GINS). Short ubiquitin chains recruit NEIL3 through direct binding, whereas longer chains are required for the unloading of CMG by the p97 ATPase, which enables the Fanconi anaemia pathway. Thus, TRAIP controls the choice between the two known pathways of replication-coupled interstrand-crosslink repair. These results, together with our other recent findings3,4 establish TRAIP as a master regulator of CMG unloading and the response of the replisome to obstacles.
Collapse
Affiliation(s)
- R Alex Wu
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA
| | - Daniel R Semlow
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA
| | | | - Olga V Kochenova
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA
| | - Gheorghe Chistol
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA
| | | | - Ravindra Amunugama
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA
| | - Justin L Sparks
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA
| | - Meng Wang
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, UK
- Department of Haematology, University of Cambridge, Cambridge, UK
| | - Lin Deng
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA
- Department of Pediatric Oncology, Dana-Farber Cancer Institute, Boston, MA, USA
- Department of Cell Biology, Harvard Medical School, Boston, MA, USA
| | - Claudia A Mimoso
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA
| | - Emily Low
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA
| | - Ketan J Patel
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, UK
- Department of Medicine, University of Cambridge, Addenbrooke's Hospital, Cambridge, UK
| | - Johannes C Walter
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA.
- Howard Hughes Medical Institute, Boston, MA, USA.
| |
Collapse
|
39
|
Rankin S. Reconstituting Nuclear and Chromosome Dynamics Using Xenopus Extracts. Cold Spring Harb Protoc 2019; 2019:pdb.top097105. [PMID: 30150319 DOI: 10.1101/pdb.top097105] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Extracts prepared from the eggs of frogs, particularly Xenopus species, have provided critical material for seminal studies of nuclear and chromosome dynamics over several decades. Their usefulness for these types of analyses lies in several important characteristics: stockpiled nuclear components, absence of endogenous DNA, and intact and functioning signaling networks. These factors have allowed detailed molecular analyses of many aspects of chromosome biology, including DNA replication, checkpoint signaling, epigenetic control, and chromosome condensation, cohesion, and segregation. In this introduction, the preparation and application of Xenopus egg extracts for the study of chromosomes and chromatin are described in detail.
Collapse
Affiliation(s)
- Susannah Rankin
- Program in Cell Cycle and Cancer Biology, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma 73104; .,Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104
| |
Collapse
|
40
|
Sparks J, Walter JC. Extracts for Analysis of DNA Replication in a Nucleus-Free System. Cold Spring Harb Protoc 2019; 2019:pdb.prot097154. [PMID: 29769389 DOI: 10.1101/pdb.prot097154] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Frog egg extracts represent a powerful approach with which to dissect molecular mechanisms of vertebrate DNA replication and repair. In the classical approach, sperm chromatin is added to a crude egg lysate to form replication-competent nuclei. We subsequently described a procedure that bypasses the requirement for nuclear assembly in DNA replication. In this method, DNA is first added to a high-speed supernatant (HSS) of egg lysate, which mimics the G1 phase of the cell cycle in that it supports replication licensing. Subsequent addition of a concentrated nucleoplasmic extract (NPE) leads to replication initiation followed by a single complete round of DNA replication. The advantage of the nucleus-free system is that it supports efficient replication of model DNA templates such as plasmids and lambda DNA that can be modified with specific features such as LacI arrays, DNA protein cross-links, or DNA interstrand cross-links. Here, we describe our current protocol for preparation of HSS and NPE. Methods for their use in DNA replication and repair are described elsewhere.
Collapse
Affiliation(s)
- Justin Sparks
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115
| | - Johannes C Walter
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115; .,Howard Hughes Medical Institute, Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115
| |
Collapse
|
41
|
da Silva EML, Rankin S. Chromosome Cohesion and Condensation in Xenopus Egg Extracts. Cold Spring Harb Protoc 2019; 2019:pdb.prot097121. [PMID: 29475994 PMCID: PMC6571020 DOI: 10.1101/pdb.prot097121] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Chromosome structure in both interphase and M-phase cells is strongly influenced by the action of the cohesin and condensin protein complexes. The cohesin complex tethers the identical copies of each chromosome, called sister chromatids, together following DNA replication and promotes normal interphase chromosome structure and gene expression. In contrast, condensin is active largely in M phase and promotes the compaction of individual chromosomes. The Xenopus egg extract system is uniquely suited to analyze the functions of both complexes. Egg extracts, in which the cell cycle state can be manipulated, contain stockpiles of nuclear proteins (including condensin and cohesin) sufficient for the assembly of thousands of nuclei per microliter. Extract prepared from unfertilized eggs is arrested by the presence of cytostatic factor (CSF) in a state with high levels of M-phase kinase activity, but can be stimulated to enter interphase, in which DNA replication occurs spontaneously. For cohesion assays, demembranated sperm nuclei are incubated in interphase extract, where they undergo rapid and synchronous DNA replication and cohesion establishment through the recruitment of proteins and other factors (e.g., nucleotides) from the extract. Sister chromatid cohesion is assessed by then driving the extract into M phase by the addition of fresh CSF-arrested extract. In contrast, because chromosome condensation occurs spontaneously in M-phase extracts, sperm nuclei are added directly to CSF extracts to assay condensation.
Collapse
Affiliation(s)
- Eulália M L da Silva
- Program in Cell Cycle and Cancer Biology, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma 73104
| | - Susannah Rankin
- Program in Cell Cycle and Cancer Biology, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma 73104;
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104
| |
Collapse
|
42
|
Lin Y, Ha A, Yan S. Methods for Studying DNA Single-Strand Break Repair and Signaling in Xenopus laevis Egg Extracts. Methods Mol Biol 2019; 1999:161-172. [PMID: 31127575 PMCID: PMC6550457 DOI: 10.1007/978-1-4939-9500-4_9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
DNA single-strand breaks (SSBs) are the most common type of DNA lesions as they are generated approximately 10,000 times per mammalian cell each day. Unrepaired SSBs compromise DNA replication and transcription programs, leading to genome instability, and have been implicated in many diseases including cancer. In this chapter, we introduce methods to study the ATR-Chk1 DNA damage response (DDR) pathway and DNA repair pathway in response to a site-specific, defined SSB plasmid in Xenopus laevis egg extracts. This experimental system can be applied in future studies to reveal many aspects of the molecular mechanisms of SSB repair and signaling in eukaryotes.
Collapse
Affiliation(s)
- Yunfeng Lin
- Department of Biological Sciences, University of North Carolina at Charlotte, Charlotte, NC, USA
| | - Anh Ha
- Department of Biological Sciences, University of North Carolina at Charlotte, Charlotte, NC, USA
| | - Shan Yan
- Department of Biological Sciences, University of North Carolina at Charlotte, Charlotte, NC, USA.
| |
Collapse
|
43
|
Larsen NB, Gao AO, Sparks JL, Gallina I, Wu RA, Mann M, Räschle M, Walter JC, Duxin JP. Replication-Coupled DNA-Protein Crosslink Repair by SPRTN and the Proteasome in Xenopus Egg Extracts. Mol Cell 2018; 73:574-588.e7. [PMID: 30595436 PMCID: PMC6375733 DOI: 10.1016/j.molcel.2018.11.024] [Citation(s) in RCA: 117] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Revised: 09/20/2018] [Accepted: 11/15/2018] [Indexed: 01/19/2023]
Abstract
DNA-protein crosslinks (DPCs) are bulky lesions that interfere with DNA metabolism and therefore threaten genomic integrity. Recent studies implicate the metalloprotease SPRTN in S phase removal of DPCs, but how SPRTN is targeted to DPCs during DNA replication is unknown. Using Xenopus egg extracts that recapitulate replication-coupled DPC proteolysis, we show that DPCs can be degraded by SPRTN or the proteasome, which act as independent DPC proteases. Proteasome recruitment requires DPC polyubiquitylation, which is partially dependent on the ubiquitin ligase activity of TRAIP. In contrast, SPRTN-mediated DPC degradation does not require DPC polyubiquitylation but instead depends on nascent strand extension to within a few nucleotides of the lesion, implying that polymerase stalling at the DPC activates SPRTN on both leading and lagging strand templates. Our results demonstrate that SPRTN and proteasome activities are coupled to DNA replication by distinct mechanisms that promote replication across immovable protein barriers.
Collapse
Affiliation(s)
- Nicolai B Larsen
- Faculty of Health and Medical Sciences, Novo Nordisk Foundation Center for Protein Research, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Alan O Gao
- Faculty of Health and Medical Sciences, Novo Nordisk Foundation Center for Protein Research, University of Copenhagen, DK-2200 Copenhagen, Denmark; Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
| | - Justin L Sparks
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
| | - Irene Gallina
- Faculty of Health and Medical Sciences, Novo Nordisk Foundation Center for Protein Research, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - R Alex Wu
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
| | - Matthias Mann
- Faculty of Health and Medical Sciences, Novo Nordisk Foundation Center for Protein Research, University of Copenhagen, DK-2200 Copenhagen, Denmark; Department of Proteomics and Signal Transduction, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | - Markus Räschle
- Department of Molecular Biotechnology and Systems Biology, Technical University of Kaiserslautern, 67653 Kaiserslautern, Germany
| | - Johannes C Walter
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA; Howard Hughes Medical Institute, Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA.
| | - Julien P Duxin
- Faculty of Health and Medical Sciences, Novo Nordisk Foundation Center for Protein Research, University of Copenhagen, DK-2200 Copenhagen, Denmark.
| |
Collapse
|
44
|
Broadus MR, Lee E. Chemical Screening Using Cell-Free Xenopus Egg Extract. Cold Spring Harb Protoc 2018; 2018:pdb.prot098277. [PMID: 29475996 DOI: 10.1101/pdb.prot098277] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Most drug screening methods use purified proteins, cultured cells, and/or small model organisms such as Xenopus, zebrafish, flies, or nematodes. These systems have proven successes in drug discovery, but they also have weaknesses. Although purified cellular components allow for identification of compounds with activity against specific targets, such systems lack the complex biological interactions present in cellular and organismal screens. In vivo systems overcome these weaknesses, but the lack of cellular permeability, efflux by cellular pumps, and/or toxicity can be major limitations. Xenopus laevis egg extract, a concentrated and biologically active cytosol, can potentially overcome these weaknesses. Drug interactions occur in a near-physiological milieu, thereby functioning in a "truer" endogenous manner than purified components. Also, Xenopus egg extract is a cell-free system that lacks intact plasma membranes that could restrict drug access to potential targets. Finally, Xenopus egg extract is readily manipulated at the protein level: Proteins are easily depleted or added to the system, an important feature for analyzing drug effects in disease states. Thus, Xenopus egg extract offers an attractive media for screening drugs that merges strengths of both in vitro and in vivo systems.
Collapse
Affiliation(s)
- Matthew R Broadus
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115
| | - Ethan Lee
- Department of Cell and Developmental Biology, Vanderbilt Ingram Cancer Center, Vanderbilt, University Medical Center, Nashville, Tennessee 37232
| |
Collapse
|
45
|
Amunugama R, Willcox S, Wu RA, Abdullah UB, El-Sagheer AH, Brown T, McHugh PJ, Griffith JD, Walter JC. Replication Fork Reversal during DNA Interstrand Crosslink Repair Requires CMG Unloading. Cell Rep 2018; 23:3419-3428. [PMID: 29924986 PMCID: PMC6086610 DOI: 10.1016/j.celrep.2018.05.061] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Revised: 03/29/2018] [Accepted: 05/17/2018] [Indexed: 01/08/2023] Open
Abstract
DNA interstrand crosslinks (ICLs) are extremely cytotoxic, but the mechanism of their repair remains incompletely understood. Using Xenopus egg extracts, we previously showed that repair of a cisplatin ICL is triggered when two replication forks converge on the lesion. After CDC45/MCM2-7/GINS (CMG) ubiquitylation and unloading by the p97 segregase, FANCI-FANCD2 promotes DNA incisions by XPF-ERCC1, leading to ICL unhooking. Here, we report that, during this cell-free ICL repair reaction, one of the two converged forks undergoes reversal. Fork reversal fails when CMG unloading is inhibited, but it does not require FANCI-FANCD2. After one fork has undergone reversal, the opposing fork that still abuts the ICL undergoes incisions. Our data show that replication fork reversal at an ICL requires replisome disassembly. We present a revised model of ICL repair that involves a reversed fork intermediate.
Collapse
Affiliation(s)
- Ravindra Amunugama
- Howard Hughes Medical Institute and Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
| | - Smaranda Willcox
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, Chapel Hill, NC 27599, USA
| | - R Alex Wu
- Howard Hughes Medical Institute and Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
| | - Ummi B Abdullah
- Department of Oncology, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, UK
| | | | - Tom Brown
- Department of Chemistry, University of Oxford, Oxford OX1 3TA, UK; Department of Oncology, University of Oxford, Old Road Campus Research Building, Oxford OX3 7DQ, UK
| | - Peter J McHugh
- Department of Oncology, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, UK
| | - Jack D Griffith
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, Chapel Hill, NC 27599, USA.
| | - Johannes C Walter
- Howard Hughes Medical Institute and Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA.
| |
Collapse
|
46
|
Nucleosomes around a mismatched base pair are excluded via an Msh2-dependent reaction with the aid of SNF2 family ATPase Smarcad1. Genes Dev 2018; 32:806-821. [PMID: 29899141 PMCID: PMC6049510 DOI: 10.1101/gad.310995.117] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Accepted: 04/27/2018] [Indexed: 01/01/2023]
Abstract
Here, Terui et al. studied the mechanisms underlying chromatin remodeling that occurs during MMR. They show that the eukaryotic MMR system has an ability to exclude local nucleosomes and identify Smarcad1/Fun30 as an accessory factor for the MMR reaction. Post-replicative correction of replication errors by the mismatch repair (MMR) system is critical for suppression of mutations. Although the MMR system may need to handle nucleosomes at the site of chromatin replication, how MMR occurs in the chromatin environment remains unclear. Here, we show that nucleosomes are excluded from a >1-kb region surrounding a mismatched base pair in Xenopus egg extracts. The exclusion was dependent on the Msh2–Msh6 mismatch recognition complex but not the Mlh1-containing MutL homologs and counteracts both the HIRA- and CAF-1 (chromatin assembly factor 1)-mediated chromatin assembly pathways. We further found that the Smarcad1 chromatin remodeling ATPase is recruited to mismatch-carrying DNA in an Msh2-dependent but Mlh1-independent manner to assist nucleosome exclusion and that Smarcad1 facilitates the repair of mismatches when nucleosomes are preassembled on DNA. In budding yeast, deletion of FUN30, the homolog of Smarcad1, showed a synergistic increase of spontaneous mutations in combination with MSH6 or MSH3 deletion but no significant increase with MSH2 deletion. Genetic analyses also suggested that the function of Fun30 in MMR is to counteract CAF-1. Our study uncovers that the eukaryotic MMR system has an ability to exclude local nucleosomes and identifies Smarcad1/Fun30 as an accessory factor for the MMR reaction.
Collapse
|
47
|
Madamba EV, Berthet EB, Francis NJ. Inheritance of Histones H3 and H4 during DNA Replication In Vitro. Cell Rep 2018; 21:1361-1374. [PMID: 29091772 DOI: 10.1016/j.celrep.2017.10.033] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Revised: 09/24/2017] [Accepted: 10/06/2017] [Indexed: 01/08/2023] Open
Abstract
Nucleosomes are believed to carry epigenetic information through the cell cycle, including through DNA replication. It has been known for decades that parental histones are reassembled on newly replicated chromatin, but the mechanisms underlying histone inheritance and dispersal during DNA replication are not fully understood. We monitored the fate of histones H3 or H4 from a single nucleosome through DNA replication in two in vitro systems. In the SV40 system, histones assembled on a single nucleosome positioning sequence can be inherited by their own daughter DNA but are dispersed from their original location. In Xenopus laevis extracts, histones are dynamic, and nucleosomes are repositioned independent of and prior to DNA replication. Nevertheless, a high fraction of histones H3 and H4 that are inherited through DNA replication remains near its starting location. Thus, inheritance of histone proteins and their dispersal can be mechanistically uncoupled.
Collapse
Affiliation(s)
- Egbert Vincent Madamba
- Department of Molecular and Cellular Biology, Harvard University, 7 Divinity Avenue, Cambridge, MA 02138, USA
| | - Ellora Bellows Berthet
- Department of Molecular and Cellular Biology, Harvard University, 7 Divinity Avenue, Cambridge, MA 02138, USA
| | - Nicole Jane Francis
- Institut de recherches clinique de Montréal (IRCM) and Département de biochimie et médecine moléculaire, Université de Montréal, Montréal, QC H2W 1R7 Canada.
| |
Collapse
|
48
|
Aze A, Fragkos M, Bocquet S, Cau J, Méchali M. RNAs coordinate nuclear envelope assembly and DNA replication through ELYS recruitment to chromatin. Nat Commun 2017; 8:2130. [PMID: 29242643 PMCID: PMC5730577 DOI: 10.1038/s41467-017-02180-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Accepted: 11/13/2017] [Indexed: 12/17/2022] Open
Abstract
Upon fertilisation, the sperm pronucleus acquires the competence to replicate the genome through a cascade of events that link chromatin remodelling to nuclear envelope formation. The factors involved have been partially identified and are poorly characterised. Here, using Xenopus laevis egg extracts we show that RNAs are required for proper nuclear envelope assembly following sperm DNA decondensation. Although chromatin remodelling and pre-replication complex formation occur normally, RNA-depleted extracts show a defect in pre-RC activation. The nuclear processes affected by RNA-depletion included ELYS recruitment, which accounts for the deficiency in nuclear pore complex assembly. This results in failure in chromatin relaxation as well as in the import and proper nuclear concentration of the S-phase kinases necessary for DNA replication activation. Our results highlight a translation-independent RNA function necessary for the parental genome progression towards the early embryonic cell cycle programme. The factors that link chromatin remodelling to nuclear envelope formation in the sperm pronucleus are not fully characterised. Here, the authors show that in RNA-depleted Xenopus laevis egg extracts, ELYS recruitment and nuclear pore complex formation are impaired, resulting in defective nuclear processes.
Collapse
Affiliation(s)
- Antoine Aze
- Institute of Human Genetics, UMR 9002, CNRS and the University of Montpellier, Replication and Genome Dynamics, 141 rue de la Cardonille, 34396, Montpellier, France.
| | - Michalis Fragkos
- Institute of Human Genetics, UMR 9002, CNRS and the University of Montpellier, Replication and Genome Dynamics, 141 rue de la Cardonille, 34396, Montpellier, France.,Institut Gustave Roussy, Genetic Stability and Oncogenesis Department, 39 rue Camille Desmoulins, 94805, Villejuif, France
| | - Stéphane Bocquet
- Institute of Human Genetics, UMR 9002, CNRS and the University of Montpellier, Replication and Genome Dynamics, 141 rue de la Cardonille, 34396, Montpellier, France
| | - Julien Cau
- Institute of Human Genetics, UMR 9002, CNRS and the University of Montpellier, Montpellier RIO Imaging, 141 rue de la Cardonille, 34396, Montpellier, France
| | - Marcel Méchali
- Institute of Human Genetics, UMR 9002, CNRS and the University of Montpellier, Replication and Genome Dynamics, 141 rue de la Cardonille, 34396, Montpellier, France.
| |
Collapse
|
49
|
Paudyal SC, Li S, Yan H, Hunter T, You Z. Dna2 initiates resection at clean DNA double-strand breaks. Nucleic Acids Res 2017; 45:11766-11781. [PMID: 28981724 PMCID: PMC5714177 DOI: 10.1093/nar/gkx830] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Revised: 08/30/2017] [Accepted: 09/06/2017] [Indexed: 02/07/2023] Open
Abstract
Nucleolytic resection of DNA double-strand breaks (DSBs) is essential for both checkpoint activation and homology-mediated repair; however, the precise mechanism of resection, especially the initiation step, remains incompletely understood. Resection of blocked ends with protein or chemical adducts is believed to be initiated by the MRN complex in conjunction with CtIP through internal cleavage of the 5' strand DNA. However, it is not clear whether resection of clean DSBs with free ends is also initiated by the same mechanism. Using the Xenopus nuclear extract system, here we show that the Dna2 nuclease directly initiates the resection of clean DSBs by cleaving the 5' strand DNA ∼10-20 nucleotides away from the ends. In the absence of Dna2, MRN together with CtIP mediate an alternative resection initiation pathway where the nuclease activity of MRN apparently directly cleaves the 5' strand DNA at more distal sites. MRN also facilitates resection initiation by promoting the recruitment of Dna2 and CtIP to the DNA substrate. The ssDNA-binding protein RPA promotes both Dna2- and CtIP-MRN-dependent resection initiation, but a RPA mutant can distinguish between these pathways. Our results strongly suggest that resection of blocked and clean DSBs is initiated via distinct mechanisms.
Collapse
Affiliation(s)
- Sharad C. Paudyal
- Department of Cell Biology and Physiology, Washington University School of Medicine, 660 S. Euclid Avenue, St. Louis, MO 63110, USA
| | - Shan Li
- Department of Cell Biology and Physiology, Washington University School of Medicine, 660 S. Euclid Avenue, St. Louis, MO 63110, USA
| | - Hong Yan
- Fox Chase Cancer Center, 333 Cottman Avenue, Philadelphia, PA 19111, USA
| | - Tony Hunter
- Salk Institute, 10010 N Torrey Pines Road, La Jolla, CA 92037, USA
| | - Zhongsheng You
- Department of Cell Biology and Physiology, Washington University School of Medicine, 660 S. Euclid Avenue, St. Louis, MO 63110, USA
| |
Collapse
|
50
|
Parisis N, Krasinska L, Harker B, Urbach S, Rossignol M, Camasses A, Dewar J, Morin N, Fisher D. Initiation of DNA replication requires actin dynamics and formin activity. EMBO J 2017; 36:3212-3231. [PMID: 28982779 DOI: 10.15252/embj.201796585] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Revised: 08/28/2017] [Accepted: 09/07/2017] [Indexed: 12/19/2022] Open
Abstract
Nuclear actin regulates transcriptional programmes in a manner dependent on its levels and polymerisation state. This dynamics is determined by the balance of nucleocytoplasmic shuttling, formin- and redox-dependent filament polymerisation. Here, using Xenopus egg extracts and human somatic cells, we show that actin dynamics and formins are essential for DNA replication. In proliferating cells, formin inhibition abolishes nuclear transport and initiation of DNA replication, as well as general transcription. In replicating nuclei from transcriptionally silent Xenopus egg extracts, we identified numerous actin regulators, and disruption of actin dynamics abrogates nuclear transport, preventing NLS (nuclear localisation signal)-cargo release from RanGTP-importin complexes. Nuclear formin activity is further required to promote loading of cyclin-dependent kinase (CDK) and proliferating cell nuclear antigen (PCNA) onto chromatin, as well as initiation and elongation of DNA replication. Therefore, actin dynamics and formins control DNA replication by multiple direct and indirect mechanisms.
Collapse
Affiliation(s)
- Nikolaos Parisis
- IGMM, CNRS Univ. Montpellier, Montpellier, France.,Laboratory of Functional Proteomics, INRA, Montpellier, France
| | | | | | - Serge Urbach
- Functional Proteomics Platform (FPP), Institute of Functional Genomics (IGF), CNRS UMR 5203 INSERM U661, Montpellier, France
| | | | | | | | | | | |
Collapse
|