1
|
Arends T, Tsuchida H, Adeyemi RO, Tapscott SJ. DUX4-induced HSATII transcription causes KDM2A/B-PRC1 nuclear foci and impairs DNA damage response. J Cell Biol 2024; 223:e202303141. [PMID: 38451221 PMCID: PMC10919155 DOI: 10.1083/jcb.202303141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Revised: 11/02/2023] [Accepted: 02/01/2024] [Indexed: 03/08/2024] Open
Abstract
Polycomb repressive complexes regulate developmental gene programs, promote DNA damage repair, and mediate pericentromeric satellite repeat repression. Expression of pericentromeric satellite repeats has been implicated in several cancers and diseases, including facioscapulohumeral dystrophy (FSHD). Here, we show that DUX4-mediated transcription of HSATII regions causes nuclear foci formation of KDM2A/B-PRC1 complexes, resulting in a global loss of PRC1-mediated monoubiquitination of histone H2A. Loss of PRC1-ubiquitin signaling severely impacts DNA damage response. Our data implicate DUX4-activation of HSATII and sequestration of KDM2A/B-PRC1 complexes as a mechanism of regulating epigenetic and DNA repair pathways.
Collapse
Affiliation(s)
- Tessa Arends
- Human Biology Division, Fred Hutchinson Cancer Center, Seattle, WA, USA
| | - Hiroshi Tsuchida
- Basic Sciences Division, Fred Hutchinson Cancer Center, Seattle, WA, USA
| | - Richard O. Adeyemi
- Basic Sciences Division, Fred Hutchinson Cancer Center, Seattle, WA, USA
| | - Stephen J. Tapscott
- Human Biology Division, Fred Hutchinson Cancer Center, Seattle, WA, USA
- Clinical Research Division, Fred Hutchinson Cancer Center, Seattle, WA, USA
- Department of Neurology, University of Washington, Seattle, WA, USA
| |
Collapse
|
2
|
Showman S, Talbert PB, Xu Y, Adeyemi RO, Henikoff S. Expansion of human centromeric arrays in cells undergoing break-induced replication. Cell Rep 2024; 43:113851. [PMID: 38427559 PMCID: PMC11034957 DOI: 10.1016/j.celrep.2024.113851] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2023] [Revised: 01/10/2024] [Accepted: 02/07/2024] [Indexed: 03/03/2024] Open
Abstract
Human centromeres are located within α-satellite arrays and evolve rapidly, which can lead to individual variation in array length. Proposed mechanisms for such alterations in length are unequal crossover between sister chromatids, gene conversion, and break-induced replication. However, the underlying molecular mechanisms responsible for the massive, complex, and homogeneous organization of centromeric arrays have not been experimentally validated. Here, we use droplet digital PCR assays to demonstrate that centromeric arrays can expand and contract within ∼20 somatic cell divisions of an alternative lengthening of telomere (ALT)-positive cell line. We find that the frequency of array variation among single-cell-derived subclones ranges from a minimum of ∼7% to a maximum of ∼100%. Further clonal evolution revealed that centromere expansion is favored over contraction. We find that the homologous recombination protein RAD52 and the helicase PIF1 are required for extensive array change, suggesting that centromere sequence evolution can occur via break-induced replication.
Collapse
Affiliation(s)
- Soyeon Showman
- Basic Sciences Division, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA; Molecular and Cellular Biology Graduate Program, University of Washington, Seattle, WA 98195, USA; Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA
| | - Paul B Talbert
- Basic Sciences Division, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA; Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA
| | - Yiling Xu
- Basic Sciences Division, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA; Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA
| | - Richard O Adeyemi
- Basic Sciences Division, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA
| | - Steven Henikoff
- Basic Sciences Division, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA; Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA.
| |
Collapse
|
3
|
Tischler JD, Tsuchida H, Bosire R, Oda TT, Park A, Adeyemi RO. FLIP(C1orf112)-FIGNL1 complex regulates RAD51 chromatin association to promote viability after replication stress. Nat Commun 2024; 15:866. [PMID: 38286805 PMCID: PMC10825145 DOI: 10.1038/s41467-024-45139-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Accepted: 01/16/2024] [Indexed: 01/31/2024] Open
Abstract
Homologous recombination (HR) plays critical roles in repairing lesions that arise during DNA replication and is thus essential for viability. RAD51 plays important roles during replication and HR, however, how RAD51 is regulated downstream of nucleofilament formation and how the varied RAD51 functions are regulated is not clear. We have investigated the protein c1orf112/FLIP that previously scored in genome-wide screens for mediators of DNA inter-strand crosslink (ICL) repair. Upon ICL agent exposure, FLIP loss leads to marked cell death, elevated chromosomal instability, increased micronuclei formation, altered cell cycle progression and increased DNA damage signaling. FLIP is recruited to damage foci and forms a complex with FIGNL1. Both proteins have epistatic roles in ICL repair, forming a stable complex. Mechanistically, FLIP loss leads to increased RAD51 amounts and foci on chromatin both with or without exogenous DNA damage, defective replication fork progression and reduced HR competency. We posit that FLIP is essential for limiting RAD51 levels on chromatin in the absence of damage and for RAD51 dissociation from nucleofilaments to properly complete HR. Failure to do so leads to replication slowing and inability to complete repair.
Collapse
Affiliation(s)
- Jessica D Tischler
- Basic Sciences Division, Fred Hutchinson Cancer Center, Seattle, WA, 98109, USA
| | - Hiroshi Tsuchida
- Basic Sciences Division, Fred Hutchinson Cancer Center, Seattle, WA, 98109, USA
| | | | - Tommy T Oda
- Basic Sciences Division, Fred Hutchinson Cancer Center, Seattle, WA, 98109, USA
- University of Washington, Seattle, 98195, USA
| | - Ana Park
- Basic Sciences Division, Fred Hutchinson Cancer Center, Seattle, WA, 98109, USA
- University of Washington, Seattle, 98195, USA
| | - Richard O Adeyemi
- Basic Sciences Division, Fred Hutchinson Cancer Center, Seattle, WA, 98109, USA.
| |
Collapse
|
4
|
Showman S, Talbert PB, Xu Y, Adeyemi RO, Henikoff S. Expansion of human centromeric arrays in cells undergoing break-induced replication. bioRxiv 2023:2023.11.11.566714. [PMID: 38014305 PMCID: PMC10680626 DOI: 10.1101/2023.11.11.566714] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
Human centromeres are located within α-satellite arrays and evolve rapidly, which can lead to individual variation in array lengths. Proposed mechanisms for such alterations in lengths are unequal cross-over between sister chromatids, gene conversion, and break-induced replication. However, the underlying molecular mechanisms responsible for the massive, complex, and homogeneous organization of centromeric arrays have not been experimentally validated. Here, we use droplet digital PCR assays to demonstrate that centromeric arrays can expand and contract within ~20 somatic cell divisions of a cell line. We find that the frequency of array variation among single-cell-derived subclones ranges from a minimum of ~7% to a maximum of ~100%. Further clonal evolution revealed that centromere expansion is favored over contraction. We find that the homologous recombination protein RAD52 and the helicase PIF1 are required for extensive array change, suggesting that centromere sequence evolution can occur via break-induced replication.
Collapse
Affiliation(s)
- Soyeon Showman
- Basic Sciences Division, Fred Hutchinson Cancer Center, Seattle, WA, USA
- Molecular and Cellular Biology Graduate Program, University of Washington, Seattle, USA
- Howard Hughes Medical Institute, Chevy Chase, MD, USA
| | - Paul B. Talbert
- Basic Sciences Division, Fred Hutchinson Cancer Center, Seattle, WA, USA
- Howard Hughes Medical Institute, Chevy Chase, MD, USA
| | - Yiling Xu
- Basic Sciences Division, Fred Hutchinson Cancer Center, Seattle, WA, USA
- Howard Hughes Medical Institute, Chevy Chase, MD, USA
| | - Richard O. Adeyemi
- Basic Sciences Division, Fred Hutchinson Cancer Center, Seattle, WA, USA
| | - Steven Henikoff
- Basic Sciences Division, Fred Hutchinson Cancer Center, Seattle, WA, USA
- Howard Hughes Medical Institute, Chevy Chase, MD, USA
| |
Collapse
|
5
|
Tischler JD, Tsuchida H, Oda TT, Park A, Adeyemi RO. RADIF(C1orf112)-FIGNL1 Complex Regulates RAD51 Chromatin Association to Promote Viability After Replication Stress. bioRxiv 2023:2023.09.25.556595. [PMID: 37808755 PMCID: PMC10557588 DOI: 10.1101/2023.09.25.556595] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/10/2023]
Abstract
Homologous recombination (HR) plays critical roles in repairing lesions that arise during DNA replication and is thus essential for viability. RAD51 plays important roles during replication and HR, however, how RAD51 is regulated downstream of nucleofilament formation and how the varied RAD51 functions are regulated is not clear. We have investigated the poorly characterized protein c1orf112/RADIF that previously scored in genome-wide screens for mediators of DNA inter-strand crosslink (ICL) repair. Upon ICL agent exposure, RADIF loss leads to marked cell death, elevated chromosomal instability, increased micronuclei formation, altered cell cycle progression and increased DNA damage signaling. RADIF is recruited to damage foci and forms a complex with FIGNL1. Both proteins have epistatic roles in ICL repair, forming a co-stable complex. Mechanistically, RADIF loss leads to increased RAD51 amounts and foci on chromatin both with or without exogenous DNA damage, defective replication fork progression and reduced HR competency. We posit that RADIF is essential for limiting RAD51 levels on chromatin in the absence of damage and for RAD51 dissociation from nucleofilaments to properly complete HR. Failure to do so leads to replication slowing and inability to complete repair.
Collapse
|
6
|
Adeyemi RO. Transcription and DNA repair collide after UV exposure. Proc Natl Acad Sci U S A 2023; 120:e2303201120. [PMID: 37036973 PMCID: PMC10120015 DOI: 10.1073/pnas.2303201120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/12/2023] Open
Affiliation(s)
- Richard O. Adeyemi
- Basic Sciences Division, Fred Hutchinson Cancer Center, Seattle, WA98109
| |
Collapse
|
7
|
Adeyemi RO, Willis NA, Elia AEH, Clairmont C, Li S, Wu X, D'Andrea AD, Scully R, Elledge SJ. The Protexin complex counters resection on stalled forks to promote homologous recombination and crosslink repair. Mol Cell 2021; 81:4440-4456.e7. [PMID: 34597596 PMCID: PMC8588999 DOI: 10.1016/j.molcel.2021.09.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2019] [Revised: 07/11/2021] [Accepted: 09/07/2021] [Indexed: 02/06/2023]
Abstract
Protection of stalled replication forks is critical to genomic stability. Using genetic and proteomic analyses, we discovered the Protexin complex containing the ssDNA binding protein SCAI and the DNA polymerase REV3. Protexin is required specifically for protecting forks stalled by nucleotide depletion, fork barriers, fragile sites, and DNA inter-strand crosslinks (ICLs), where it promotes homologous recombination and repair. Protexin loss leads to ssDNA accumulation and profound genomic instability in response to ICLs. Protexin interacts with RNA POL2, and both oppose EXO1's resection of DNA on forks remodeled by the FANCM translocase activity. This pathway acts independently of BRCA/RAD51-mediated fork stabilization, and cells with BRCA2 mutations were dependent on SCAI for survival. These data suggest that Protexin and its associated factors establish a new fork protection pathway that counteracts fork resection in part through a REV3 polymerase-dependent resynthesis mechanism of excised DNA, particularly at ICL stalled forks.
Collapse
Affiliation(s)
- Richard O Adeyemi
- Department of Genetics, Harvard Medical School, and Division of Genetics, Brigham and Women's Hospital, Howard Hughes Medical Institute, Boston, MA 02115, USA
| | - Nicholas A Willis
- Department of Medicine and Cancer Research Institute, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | - Andrew E H Elia
- Department of Genetics, Harvard Medical School, and Division of Genetics, Brigham and Women's Hospital, Howard Hughes Medical Institute, Boston, MA 02115, USA
| | - Connor Clairmont
- Department of Radiation Oncology and Center for DNA Damage and Repair, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02215, USA
| | - Shibo Li
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Xiaohua Wu
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Alan D D'Andrea
- Department of Radiation Oncology and Center for DNA Damage and Repair, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02215, USA
| | - Ralph Scully
- Department of Medicine and Cancer Research Institute, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | - Stephen J Elledge
- Department of Genetics, Harvard Medical School, and Division of Genetics, Brigham and Women's Hospital, Howard Hughes Medical Institute, Boston, MA 02115, USA.
| |
Collapse
|
8
|
Guerra SL, Maertens O, Kuzmickas R, De Raedt T, Adeyemi RO, Guild CJ, Guillemette S, Redig AJ, Chambers ES, Xu M, Tiv H, Santagata S, Jänne PA, Elledge SJ, Cichowski K. A Deregulated HOX Gene Axis Confers an Epigenetic Vulnerability in KRAS-Mutant Lung Cancers. Cancer Cell 2020; 37:705-719.e6. [PMID: 32243838 PMCID: PMC10805385 DOI: 10.1016/j.ccell.2020.03.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Revised: 11/12/2019] [Accepted: 03/03/2020] [Indexed: 01/02/2023]
Abstract
While KRAS mutations are common in non-small cell lung cancer (NSCLC), effective treatments are lacking. Here, we report that half of KRAS-mutant NSCLCs aberrantly express the homeobox protein HOXC10, largely due to unappreciated defects in PRC2, which confers sensitivity to combined BET/MEK inhibitors in xenograft and PDX models. Efficacy of the combination is dependent on suppression of HOXC10 by BET inhibitors. We further show that HOXC10 regulates the expression of pre-replication complex (pre-RC) proteins in sensitive tumors. Accordingly, BET/MEK inhibitors suppress pre-RC proteins in cycling cells, triggering stalled replication, DNA damage, and death. These studies reveal a promising therapeutic strategy for KRAS-mutant NSCLCs, identify a predictive biomarker of response, and define a subset of NSCLCs with a targetable epigenetic vulnerability.
Collapse
Affiliation(s)
- Stephanie L Guerra
- Genetics Division, Department of Medicine, Brigham and Women's Hospital, Boston, MA 02115, USA; Harvard Medical School, Boston, MA 02115, USA
| | - Ophélia Maertens
- Genetics Division, Department of Medicine, Brigham and Women's Hospital, Boston, MA 02115, USA; Harvard Medical School, Boston, MA 02115, USA
| | - Ryan Kuzmickas
- Genetics Division, Department of Medicine, Brigham and Women's Hospital, Boston, MA 02115, USA; Harvard Medical School, Boston, MA 02115, USA
| | - Thomas De Raedt
- Genetics Division, Department of Medicine, Brigham and Women's Hospital, Boston, MA 02115, USA; Harvard Medical School, Boston, MA 02115, USA
| | - Richard O Adeyemi
- Genetics Division, Department of Medicine, Brigham and Women's Hospital, Boston, MA 02115, USA; Harvard Medical School, Boston, MA 02115, USA
| | - Caroline J Guild
- Genetics Division, Department of Medicine, Brigham and Women's Hospital, Boston, MA 02115, USA; Harvard Medical School, Boston, MA 02115, USA
| | - Shawna Guillemette
- Genetics Division, Department of Medicine, Brigham and Women's Hospital, Boston, MA 02115, USA; Harvard Medical School, Boston, MA 02115, USA
| | - Amanda J Redig
- Lowe Center for Thoracic Oncology, Dana-Farber Cancer Institute, Boston, MA 02115, USA
| | - Emily S Chambers
- Lowe Center for Thoracic Oncology, Dana-Farber Cancer Institute, Boston, MA 02115, USA
| | - Man Xu
- Belfer Center for Applied Cancer Science, Boston, MA 02115, USA
| | - Hong Tiv
- Experimental Therapeutic Core, Dana-Farber Cancer Institute, Boston, MA 02115, USA
| | - Sandro Santagata
- Harvard Medical School, Boston, MA 02115, USA; Departments of Pathology, Brigham and Women's Hospital, Dana-Farber Cancer Institute, Boston, MA 02115, USA; Ludwig Center at Harvard, Harvard Medical School, Boston, MA 02115, USA
| | - Pasi A Jänne
- Harvard Medical School, Boston, MA 02115, USA; Lowe Center for Thoracic Oncology, Dana-Farber Cancer Institute, Boston, MA 02115, USA; Belfer Center for Applied Cancer Science, Boston, MA 02115, USA
| | - Stephen J Elledge
- Genetics Division, Department of Medicine, Brigham and Women's Hospital, Boston, MA 02115, USA; Ludwig Center at Harvard, Harvard Medical School, Boston, MA 02115, USA; Department of Genetics, Harvard Medical School, Boston, MA 02115, USA; Howard Hughes Medical Institute, 77 Avenue Louis Pasteur, Boston, MA 02115, USA
| | - Karen Cichowski
- Genetics Division, Department of Medicine, Brigham and Women's Hospital, Boston, MA 02115, USA; Harvard Medical School, Boston, MA 02115, USA; Ludwig Center at Harvard, Harvard Medical School, Boston, MA 02115, USA.
| |
Collapse
|
9
|
Mengwasser KE, Adeyemi RO, Leng Y, Choi MY, Clairmont C, D'Andrea AD, Elledge SJ. Genetic Screens Reveal FEN1 and APEX2 as BRCA2 Synthetic Lethal Targets. Mol Cell 2019. [PMID: 30686591 DOI: 10.1016/j.molcel.2018.12.008]] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
BRCA1 or BRCA2 inactivation drives breast and ovarian cancer but also creates vulnerability to poly(ADP-ribose) polymerase (PARP) inhibitors. To search for additional targets whose inhibition is synthetically lethal in BRCA2-deficient backgrounds, we screened two pairs of BRCA2 isogenic cell lines with DNA-repair-focused small hairpin RNA (shRNA) and CRISPR (clustered regularly interspaced short palindromic repeats)-based libraries. We found that BRCA2-deficient cells are selectively dependent on multiple pathways including base excision repair, ATR signaling, and splicing. We identified APEX2 and FEN1 as synthetic lethal genes with both BRCA1 and BRCA2 loss of function. BRCA2-deficient cells require the apurinic endonuclease activity and the PCNA-binding domain of Ape2 (APEX2), but not Ape1 (APEX1). Furthermore, BRCA2-deficient cells require the 5' flap endonuclease but not the 5'-3' exonuclease activity of Fen1, and chemically inhibiting Fen1 selectively targets BRCA-deficient cells. Finally, we developed a microhomology-mediated end-joining (MMEJ) reporter and showed that Fen1 participates in MMEJ, underscoring the importance of MMEJ as a collateral repair pathway in the context of homologous recombination (HR) deficiency.
Collapse
Affiliation(s)
- Kristen E Mengwasser
- Howard Hughes Medical Institute, Department of Genetics, Ludwig Center, Harvard Medical School, Boston, MA 02115, USA; Division of Genetics, Brigham and Women's Hospital, Boston, MA 02115, USA
| | - Richard O Adeyemi
- Howard Hughes Medical Institute, Department of Genetics, Ludwig Center, Harvard Medical School, Boston, MA 02115, USA; Division of Genetics, Brigham and Women's Hospital, Boston, MA 02115, USA
| | - Yumei Leng
- Howard Hughes Medical Institute, Department of Genetics, Ludwig Center, Harvard Medical School, Boston, MA 02115, USA; Division of Genetics, Brigham and Women's Hospital, Boston, MA 02115, USA
| | - Mei Yuk Choi
- Howard Hughes Medical Institute, Department of Genetics, Ludwig Center, Harvard Medical School, Boston, MA 02115, USA; Division of Genetics, Brigham and Women's Hospital, Boston, MA 02115, USA
| | - Connor Clairmont
- Department of Radiation Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02215, USA
| | - Alan D D'Andrea
- Department of Radiation Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02215, USA
| | - Stephen J Elledge
- Howard Hughes Medical Institute, Department of Genetics, Ludwig Center, Harvard Medical School, Boston, MA 02115, USA; Division of Genetics, Brigham and Women's Hospital, Boston, MA 02115, USA.
| |
Collapse
|
10
|
Mengwasser KE, Adeyemi RO, Leng Y, Choi MY, Clairmont C, D'Andrea AD, Elledge SJ. Genetic Screens Reveal FEN1 and APEX2 as BRCA2 Synthetic Lethal Targets. Mol Cell 2019; 73:885-899.e6. [PMID: 30686591 DOI: 10.1016/j.molcel.2018.12.008] [Citation(s) in RCA: 124] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Revised: 09/24/2018] [Accepted: 12/12/2018] [Indexed: 11/15/2022]
Abstract
BRCA1 or BRCA2 inactivation drives breast and ovarian cancer but also creates vulnerability to poly(ADP-ribose) polymerase (PARP) inhibitors. To search for additional targets whose inhibition is synthetically lethal in BRCA2-deficient backgrounds, we screened two pairs of BRCA2 isogenic cell lines with DNA-repair-focused small hairpin RNA (shRNA) and CRISPR (clustered regularly interspaced short palindromic repeats)-based libraries. We found that BRCA2-deficient cells are selectively dependent on multiple pathways including base excision repair, ATR signaling, and splicing. We identified APEX2 and FEN1 as synthetic lethal genes with both BRCA1 and BRCA2 loss of function. BRCA2-deficient cells require the apurinic endonuclease activity and the PCNA-binding domain of Ape2 (APEX2), but not Ape1 (APEX1). Furthermore, BRCA2-deficient cells require the 5' flap endonuclease but not the 5'-3' exonuclease activity of Fen1, and chemically inhibiting Fen1 selectively targets BRCA-deficient cells. Finally, we developed a microhomology-mediated end-joining (MMEJ) reporter and showed that Fen1 participates in MMEJ, underscoring the importance of MMEJ as a collateral repair pathway in the context of homologous recombination (HR) deficiency.
Collapse
Affiliation(s)
- Kristen E Mengwasser
- Howard Hughes Medical Institute, Department of Genetics, Ludwig Center, Harvard Medical School, Boston, MA 02115, USA; Division of Genetics, Brigham and Women's Hospital, Boston, MA 02115, USA
| | - Richard O Adeyemi
- Howard Hughes Medical Institute, Department of Genetics, Ludwig Center, Harvard Medical School, Boston, MA 02115, USA; Division of Genetics, Brigham and Women's Hospital, Boston, MA 02115, USA
| | - Yumei Leng
- Howard Hughes Medical Institute, Department of Genetics, Ludwig Center, Harvard Medical School, Boston, MA 02115, USA; Division of Genetics, Brigham and Women's Hospital, Boston, MA 02115, USA
| | - Mei Yuk Choi
- Howard Hughes Medical Institute, Department of Genetics, Ludwig Center, Harvard Medical School, Boston, MA 02115, USA; Division of Genetics, Brigham and Women's Hospital, Boston, MA 02115, USA
| | - Connor Clairmont
- Department of Radiation Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02215, USA
| | - Alan D D'Andrea
- Department of Radiation Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02215, USA
| | - Stephen J Elledge
- Howard Hughes Medical Institute, Department of Genetics, Ludwig Center, Harvard Medical School, Boston, MA 02115, USA; Division of Genetics, Brigham and Women's Hospital, Boston, MA 02115, USA.
| |
Collapse
|
11
|
Abstract
Parvoviruses halt cell cycle progression following initiation of their replication during S-phase and continue to replicate their genomes for extended periods of time in arrested cells. The parvovirus minute virus of mice (MVM) induces a DNA damage response that is required for viral replication and induction of the S/G2 cell cycle block. However, p21 and Chk1, major effectors typically associated with S-phase and G2-phase cell cycle arrest in response to diverse DNA damage stimuli, are either down-regulated, or inactivated, respectively, during MVM infection. This suggested that parvoviruses can modulate cell cycle progression by another mechanism. In this work we show that the MVM-induced, p21- and Chk1-independent, cell cycle block proceeds via a two-step process unlike that seen in response to other DNA-damaging agents or virus infections. MVM infection induced Chk2 activation early in infection which led to a transient S-phase block associated with proteasome-mediated CDC25A degradation. This step was necessary for efficient viral replication; however, Chk2 activation and CDC25A loss were not sufficient to keep infected cells in the sustained G2-arrested state which characterizes this infection. Rather, although the phosphorylation of CDK1 that normally inhibits entry into mitosis was lost, the MVM induced DDR resulted first in a targeted mis-localization and then significant depletion of cyclin B1, thus directly inhibiting cyclin B1-CDK1 complex function and preventing mitotic entry. MVM infection thus uses a novel strategy to ensure a pseudo S-phase, pre-mitotic, nuclear environment for sustained viral replication. DNA viruses induce cellular DNA damage responses that can present a block to infection that must be overcome, or alternatively, can be utilized to viral advantage. Parvoviruses, the only known viruses of vertebrates that contain single-stranded linear DNA genomes, induce a robust DNA damage response (DDR) that features a cell cycle arrest that facilitates their replication. We show that the autonomous parvovirus MVM-induced cell cycle arrest is caused by a novel two-step mechanism that ensures a pseudo S phase, pre-mitotic, nuclear environment for sustained viral replication. A feature of this arrest is virally-induced depletion of the critical cell cycle regulator cyclin B1. Parvoviruses are important infectious agents that infect many vertebrate species including humans, and our study makes an important contribution to how these viruses achieve productive infection in host cells.
Collapse
Affiliation(s)
- Richard O. Adeyemi
- University of Missouri-Columbia, School of Medicine, Columbia, Missouri, United States of America
| | - David J. Pintel
- University of Missouri-Columbia, School of Medicine, Columbia, Missouri, United States of America
- * E-mail:
| |
Collapse
|
12
|
Adeyemi RO, Landry S, Davis ME, Weitzman MD, Pintel DJ. Parvovirus minute virus of mice induces a DNA damage response that facilitates viral replication. PLoS Pathog 2010; 6:e1001141. [PMID: 20949077 PMCID: PMC2951379 DOI: 10.1371/journal.ppat.1001141] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2010] [Accepted: 09/08/2010] [Indexed: 01/04/2023] Open
Abstract
Infection by DNA viruses can elicit DNA damage responses (DDRs) in host cells. In some cases the DDR presents a block to viral replication that must be overcome, and in other cases the infecting agent exploits the DDR to facilitate replication. We find that low multiplicity infection with the autonomous parvovirus minute virus of mice (MVM) results in the activation of a DDR, characterized by the phosphorylation of H2AX, Nbs1, RPA32, Chk2 and p53. These proteins are recruited to MVM replication centers, where they co-localize with the main viral replication protein, NS1. The response is seen in both human and murine cell lines following infection with either the MVMp or MVMi strains. Replication of the virus is required for DNA damage signaling. Damage response proteins, including the ATM kinase, accumulate in viral-induced replication centers. Using mutant cell lines and specific kinase inhibitors, we show that ATM is the main transducer of the signaling events in the normal murine host. ATM inhibitors restrict MVM replication and ameliorate virus-induced cell cycle arrest, suggesting that DNA damage signaling facilitates virus replication, perhaps in part by promoting cell cycle arrest. Thus it appears that MVM exploits the cellular DNA damage response machinery early in infection to enhance its replication in host cells.
Collapse
Affiliation(s)
- Richard O. Adeyemi
- University of Missouri-Columbia, School of Medicine, Columbia, Missouri, United States of America
| | | | - Meredith E. Davis
- University of Missouri-Columbia, School of Medicine, Columbia, Missouri, United States of America
| | | | - David J. Pintel
- University of Missouri-Columbia, School of Medicine, Columbia, Missouri, United States of America
- * E-mail:
| |
Collapse
|