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Previtali V, Myers SH, Poppi L, Wynne K, Casamassima I, Girotto S, Di Stefano G, Farabegoli F, Roberti M, Oliviero G, Cavalli A. Preomic profile of BxPC-3 cells after treatment with BRC4. J Proteomics 2023; 288:104983. [PMID: 37536521 DOI: 10.1016/j.jprot.2023.104983] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Revised: 07/26/2023] [Accepted: 07/26/2023] [Indexed: 08/05/2023]
Abstract
BRCA2 and RAD51 are two proteins that play a central role in homologous recombination (HR) and DNA double strand break (DSB) repair. BRCA2 assists RAD51 fibrillation and defibrillation through binding with its eight BRC repeats, with BRC4 being one of the most efficient and best characterized. RAD51 inactivation by small molecules has been proposed as a strategy to impair BRCA2/RAD51 binding and, ultimately, the HR pathway, with the aim of making cancer cells more sensitive to PARP inhibitors (PARPi). This strategy, which mimics a synthetic lethality (SL) approach, has been successfully performed in vitro by using the myristoylated derivative of BRC4 (myr-BRC4), designed for a more efficient cell entry. The present study applies a method to obtain a proteomic fingerprint after cellular treatment with the myr-BRC4 peptide using a mass spectroscopy (MS) proteomic approach. (Data are available via ProteomeXchange with identifier PXD042696.) We performed a comparative proteomic profiling of the myr-BRC4 treated vs. untreated BxPC-3 pancreatic cancer cells and evaluated the differential expression of proteins. Among the identified proteins, we focused our attention on proteins shared by both the RAD51 and the BRCA2 interactomes, and on those whose reduction showed high statistical significance. Three downregulated proteins were identified (FANCI, FANCD2, and RPA3), and protein downregulation was confirmed through immunoblotting analysis, validating the MS approach. Our results suggest that, being a direct consequence of myr-BRC4 treatment, the detection of FANCD2, FANCI, and RPA3 downregulation could be used as an indicator for monitoring HR impairment. SIGNIFICANCE: RAD51's inhibition has gained increasing attention because of its possible implications in personalized medicine through the SL approach. Chemical disruption of protein-protein interactions (PPIs) between RAD51 and BRCA2, or some of its partner proteins, could potentiate PARPi DNA damage-induced cell death. This could have application for difficult to treat cancers, such as BRCA-competent and olaparib (PARPi) resistant pancreatic adenocarcinoma. Despite RAD51 being a widely studied target, researchers still lack detailed mechanistic information. This has stifled progress in the field with only a few RAD51 inhibitors having been identified, none of which have gained regulatory approval. Nevertheless, the peptide BRC4 is one of the most specific and best characterized RAD51 binder and inhibitor reported to date. Our study is the first to report the proteomic fingerprint consequent to cellular treatment of myr-BRC4, to offer a reference for the discovery of specific protein/pathway alterations within DNA damage repair. Our results suggest that, being a direct consequence of myr-BRC4 treatment, and ultimately ofBRCA2/RAD51 disruption, the detection of FANCD2, FANCI, and RPA3 downregulation could be used as an indicator for monitoring DNA damage repair impairment and therefore be used to potentiate the development of new effective therapeutic strategies.
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Affiliation(s)
- Viola Previtali
- Computational & Chemical Biology, Istituto Italiano di Tecnologia, 16163 Genova, Italy
| | - Samuel H Myers
- Computational & Chemical Biology, Istituto Italiano di Tecnologia, 16163 Genova, Italy
| | - Laura Poppi
- Department of Pharmacy and Biotechnology, University of Bologna, 40126 Bologna, Italy
| | - Kieran Wynne
- Systems Biology Ireland, School of Medicine, University College Dublin, Belfield Dublin 4, Ireland; Conway Institute of Biomolecular & Biomedical Research, University College Dublin, Dublin 4, Ireland
| | - Irene Casamassima
- Computational & Chemical Biology, Istituto Italiano di Tecnologia, 16163 Genova, Italy
| | - Stefania Girotto
- Computational & Chemical Biology, Istituto Italiano di Tecnologia, 16163 Genova, Italy; Structural Biophysics and Translational Pharmacology Facility, Istituto Italiano di Tecnologia, via Morego 30, 16163 Genova, Italy
| | - Giuseppina Di Stefano
- Department of Surgical and Medical Sciences, University of Bologna, 40126 Bologna, Italy
| | - Fulvia Farabegoli
- Department of Pharmacy and Biotechnology, University of Bologna, 40126 Bologna, Italy
| | - Marinella Roberti
- Department of Pharmacy and Biotechnology, University of Bologna, 40126 Bologna, Italy
| | - Giorgio Oliviero
- Systems Biology Ireland, School of Medicine, University College Dublin, Belfield Dublin 4, Ireland
| | - Andrea Cavalli
- Computational & Chemical Biology, Istituto Italiano di Tecnologia, 16163 Genova, Italy; Department of Pharmacy and Biotechnology, University of Bologna, 40126 Bologna, Italy.
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2
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Application of neural network-based image analysis to detect sister chromatid cohesion defects. Sci Rep 2023; 13:2133. [PMID: 36747022 PMCID: PMC9902603 DOI: 10.1038/s41598-023-28742-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Accepted: 01/24/2023] [Indexed: 02/08/2023] Open
Abstract
Sister chromatid cohesion (SCC) is mediated by the cohesin complex and its regulatory proteins. To evaluate the involvement of a protein in cohesin regulation, preparations of metaphase chromosome spreads and classifications of chromosome shapes after depletion of the target protein are commonly employed. Although this is a convenient and approved method, the evaluation and classification of each chromosome shape has to be performed manually by researchers. Therefore, this method is time consuming, and the results might be affected by the subjectivity of researchers. In this study, we developed neural network-based image recognition models to judge the positional relationship of sister chromatids, and thereby detect SCC defects. Transfer learning models based on SqueeezeNet or ResNet-18 were trained with more than 600 chromosome images labeled with the type of chromosome, which were classified according to the positional relationship between sister chromatids. The SqueezeNet-based trained model achieved a concordance rate of 73.1% with the sample answers given by a researcher. Importantly, the model successfully detected the SCC defect in the CTF18 deficient cell line, which was used as an SCC-defective model. These results indicate that neural-network-based image recognition models are valuable tools for examining SCC defects in different genetic backgrounds.
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3
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Bolgi O, Silva-Garcia M, Ross B, Pilla E, Kari V, Killisch M, Spitzner M, Stark N, Lenz C, Weiss K, Donzelli L, Gorrell MD, Grade M, Riemer J, Urlaub H, Dobbelstein M, Huber R, Geiss-Friedlander R. Dipeptidyl peptidase 9 triggers BRCA2 degradation and promotes DNA damage repair. EMBO Rep 2022; 23:e54136. [PMID: 35912982 PMCID: PMC9535758 DOI: 10.15252/embr.202154136] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Revised: 07/01/2022] [Accepted: 07/07/2022] [Indexed: 12/30/2022] Open
Abstract
N-terminal sequences are important sites for post-translational modifications that alter protein localization, activity, and stability. Dipeptidyl peptidase 9 (DPP9) is a serine aminopeptidase with the rare ability to cleave off N-terminal dipeptides with imino acid proline in the second position. Here, we identify the tumor-suppressor BRCA2 as a DPP9 substrate and show this interaction to be induced by DNA damage. We present crystallographic structures documenting intracrystalline enzymatic activity of DPP9, with the N-terminal Met1-Pro2 of a BRCA21-40 peptide captured in its active site. Intriguingly, DPP9-depleted cells are hypersensitive to genotoxic agents and are impaired in the repair of DNA double-strand breaks by homologous recombination. Mechanistically, DPP9 targets BRCA2 for degradation and promotes the formation of RAD51 foci, the downstream function of BRCA2. N-terminal truncation mutants of BRCA2 that mimic a DPP9 product phenocopy reduced BRCA2 stability and rescue RAD51 foci formation in DPP9-deficient cells. Taken together, we present DPP9 as a regulator of BRCA2 stability and propose that by fine-tuning the cellular concentrations of BRCA2, DPP9 alters the BRCA2 interactome, providing a possible explanation for DPP9's role in cancer.
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Affiliation(s)
- Oguz Bolgi
- Institute of Molecular Medicine and Cell Research, Medical Faculty, University of Freiburg, Freiburg, Germany.,Department of Molecular Biology, University Medical Center Göttingen, Göttingen, Germany
| | - Maria Silva-Garcia
- Department of Molecular Biology, University Medical Center Göttingen, Göttingen, Germany
| | - Breyan Ross
- Max Planck Institut für Biochemie, Martinsried, Germany.,Proteros Biostructures GmbH, Martinsried, Germany
| | - Esther Pilla
- Department of Molecular Biology, University Medical Center Göttingen, Göttingen, Germany
| | - Vijayalakshmi Kari
- Department of General, Visceral and Pediatric Surgery, University Medical Center Göttingen, Göttingen, Germany
| | - Markus Killisch
- Department of Molecular Biology, University Medical Center Göttingen, Göttingen, Germany
| | - Melanie Spitzner
- Department of General, Visceral and Pediatric Surgery, University Medical Center Göttingen, Göttingen, Germany
| | - Nadine Stark
- Institute of Molecular Oncology, Göttingen Center of Molecular Biosciences (GZMB), University Medical Center Göttingen, Göttingen, Germany
| | - Christof Lenz
- Bioanalytics, Institute of Clinical Chemistry, University Medical Center, Göttingen, Germany.,Bioanalytical Mass Spectrometry Group, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Konstantin Weiss
- Institute of Biochemistry, Redox Biochemistry, and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
| | - Laura Donzelli
- Institute of Molecular Medicine and Cell Research, Medical Faculty, University of Freiburg, Freiburg, Germany
| | - Mark D Gorrell
- Centenary Institute, The University of Sydney Faculty of Medicine and Health, Sydney, NSW, Australia
| | - Marian Grade
- Department of General, Visceral and Pediatric Surgery, University Medical Center Göttingen, Göttingen, Germany
| | - Jan Riemer
- Institute of Biochemistry, Redox Biochemistry, and Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
| | - Henning Urlaub
- Bioanalytics, Institute of Clinical Chemistry, University Medical Center, Göttingen, Germany.,Bioanalytical Mass Spectrometry Group, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Matthias Dobbelstein
- Institute of Molecular Oncology, Göttingen Center of Molecular Biosciences (GZMB), University Medical Center Göttingen, Göttingen, Germany
| | - Robert Huber
- Max Planck Institut für Biochemie, Martinsried, Germany.,Zentrum für Medizinische Biotechnologie, Universität Duisburg-Essen, Essen, Germany.,Fakultät für Chemie, Technische Universität München, Garching, Germany
| | - Ruth Geiss-Friedlander
- Institute of Molecular Medicine and Cell Research, Medical Faculty, University of Freiburg, Freiburg, Germany.,Department of Molecular Biology, University Medical Center Göttingen, Göttingen, Germany
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4
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Kawasumi R, Abe T, Psakhye I, Miyata K, Hirota K, Branzei D. Vertebrate CTF18 and DDX11 essential function in cohesion is bypassed by preventing WAPL-mediated cohesin release. Genes Dev 2021; 35:1368-1382. [PMID: 34503989 PMCID: PMC8494208 DOI: 10.1101/gad.348581.121] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Accepted: 08/16/2021] [Indexed: 01/26/2023]
Abstract
The alternative PCNA loader containing CTF18-DCC1-CTF8 facilitates sister chromatid cohesion (SCC) by poorly defined mechanisms. Here we found that in DT40 cells, CTF18 acts complementarily with the Warsaw breakage syndrome DDX11 helicase in mediating SCC and proliferation. We uncover that the lethality and cohesion defects of ctf18 ddx11 mutants are associated with reduced levels of chromatin-bound cohesin and rescued by depletion of WAPL, a cohesin-removal factor. On the contrary, high levels of ESCO1/2 acetyltransferases that acetylate cohesin to establish SCC do not rescue ctf18 ddx11 phenotypes. Notably, the tight proximity of sister centromeres and increased anaphase bridges characteristic of WAPL-depleted cells are abrogated by loss of both CTF18 and DDX11 The results reveal that vertebrate CTF18 and DDX11 collaborate to provide sufficient amounts of chromatin-loaded cohesin available for SCC generation in the presence of WAPL-mediated cohesin-unloading activity. This process modulates chromosome structure and is essential for cellular proliferation in vertebrates.
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Affiliation(s)
- Ryotaro Kawasumi
- International Foundation of Medicine (IFOM), the Fondazione Italiana per la Ricerca sul Cancro (FIRC) Institute for Molecular Oncology Foundation, Milan 20139, Italy
| | - Takuya Abe
- International Foundation of Medicine (IFOM), the Fondazione Italiana per la Ricerca sul Cancro (FIRC) Institute for Molecular Oncology Foundation, Milan 20139, Italy
- Department of Chemistry, Graduate School of Science and Engineering, Tokyo Metropolitan University, Hachioji-shi, Tokyo 192-0397, Japan
| | - Ivan Psakhye
- International Foundation of Medicine (IFOM), the Fondazione Italiana per la Ricerca sul Cancro (FIRC) Institute for Molecular Oncology Foundation, Milan 20139, Italy
| | - Keiji Miyata
- Department of Chemistry, Graduate School of Science and Engineering, Tokyo Metropolitan University, Hachioji-shi, Tokyo 192-0397, Japan
| | - Kouji Hirota
- Department of Chemistry, Graduate School of Science and Engineering, Tokyo Metropolitan University, Hachioji-shi, Tokyo 192-0397, Japan
| | - Dana Branzei
- International Foundation of Medicine (IFOM), the Fondazione Italiana per la Ricerca sul Cancro (FIRC) Institute for Molecular Oncology Foundation, Milan 20139, Italy
- Istituto di Genetica Molecolare, Consiglio Nazionale delle Ricerche (IGM-CNR), Pavia 27100, Italy
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5
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Abe T, Suzuki Y, Ikeya T, Hirota K. Targeting chromosome trisomy for chromosome editing. Sci Rep 2021; 11:18054. [PMID: 34508128 PMCID: PMC8433146 DOI: 10.1038/s41598-021-97580-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Accepted: 08/25/2021] [Indexed: 11/09/2022] Open
Abstract
A trisomy is a type of aneuploidy characterised by an additional chromosome. The additional chromosome theoretically accepts any kind of changes since it is not necessary for cellular proliferation. This advantage led us to apply two chromosome manipulation methods to autosomal trisomy in chicken DT40 cells. We first corrected chromosome 2 trisomy to disomy by employing counter-selection markers. Upon construction of cells carrying markers targeted in one of the trisomic chromosome 2s, cells that have lost markers integrated in chromosome 2 were subsequently selected. The loss of one of the chromosome 2s had little impacts on the proliferative capacity, indicating unsubstantial role of the additional chromosome 2 in DT40 cells. We next tested large-scale truncations of chromosome 2 to make a mini-chromosome for the assessment of chromosome stability by introducing telomere repeat sequences to delete most of p-arm or q-arm of chromosome 2. The obtained cell lines had 0.7 Mb mini-chromosome, and approximately 0.2% of mini-chromosome was lost per cell division in wild-type background while the rate of chromosome loss was significantly increased by the depletion of DDX11, a cohesin regulatory protein. Collectively, our findings propose that trisomic chromosomes are good targets to make unique artificial chromosomes.
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Affiliation(s)
- Takuya Abe
- Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Minamiosawa 1-1, Hachioji-shi, Tokyo, 192-0397, Japan.
| | - Yuya Suzuki
- Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Minamiosawa 1-1, Hachioji-shi, Tokyo, 192-0397, Japan
| | - Teppei Ikeya
- Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Minamiosawa 1-1, Hachioji-shi, Tokyo, 192-0397, Japan
| | - Kouji Hirota
- Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Minamiosawa 1-1, Hachioji-shi, Tokyo, 192-0397, Japan
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6
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Kojima K, Ooka M, Abe T, Hirota K. Pold4, the fourth subunit of replicative polymerase δ, suppresses gene conversion in the immunoglobulin-variable gene in avian DT40 cells. DNA Repair (Amst) 2021; 100:103056. [PMID: 33588156 DOI: 10.1016/j.dnarep.2021.103056] [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: 12/22/2020] [Revised: 01/26/2021] [Accepted: 01/28/2021] [Indexed: 10/22/2022]
Abstract
The replicative polymerase δ (Polδ), consisting of four subunits, plays a pivotal role in chromosomal replication. Pold4, the smallest subunit of Polδ, is believed to contribute to the regulation of replication by facilitating repair in response to DNA damage. However, that contribution has not been fully elucidated. We here show that Pold4 contributes to the suppression of gene conversion in immunoglobulin-variable (IgV) gene diversification in the chicken DT40 lymphocyte cell line, where gene conversion diversifies the IgV gene through intragenic homologous recombination (HR) between diverged pseudo-V segments. IgV gene conversion is initiated by activation-induced cytidine deaminase-mediated uracil formation in the IgV gene, which in turn converts into an abasic site, leading to replication arrest. POLD4-/- cells exhibited an increased rate of IgV gene conversion. Moreover, the gene-conversion tract was lengthened and the usage of pseudo-V segments was altered, showing a preference, to use the diverged sequence as a donor in POLD4-/- cells. These data suggest that Pold4 is involved in the regulation of HR-mediated gene conversion in IgV diversification. By contrast, the rate in HR-mediated, sister-chromatid exchange and gene-targeting induced by an I-SceI endonclease-mediated DNA double-strand break exhibited by POLD4-/- cells was indistinguishable from that by wild-type cells. These findings indicate that the functionality of general HR is preserved in POLD4-/- cells. In conclusion, Pold4 is involved in the suppression of IgV-gene conversion without affecting the general functionality of HR.
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Affiliation(s)
- Kota Kojima
- Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Minamiosawa 1-1, Hachioji-shi, Tokyo, 192-0397, Japan
| | - Masato Ooka
- Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Minamiosawa 1-1, Hachioji-shi, Tokyo, 192-0397, Japan
| | - Takuya Abe
- Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Minamiosawa 1-1, Hachioji-shi, Tokyo, 192-0397, Japan
| | - Kouji Hirota
- Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Minamiosawa 1-1, Hachioji-shi, Tokyo, 192-0397, Japan.
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7
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Póti Á, Gyergyák H, Németh E, Rusz O, Tóth S, Kovácsházi C, Chen D, Szikriszt B, Spisák S, Takeda S, Szakács G, Szallasi Z, Richardson AL, Szüts D. Correlation of homologous recombination deficiency induced mutational signatures with sensitivity to PARP inhibitors and cytotoxic agents. Genome Biol 2019; 20:240. [PMID: 31727117 PMCID: PMC6857305 DOI: 10.1186/s13059-019-1867-0] [Citation(s) in RCA: 65] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Accepted: 10/28/2019] [Indexed: 01/19/2023] Open
Abstract
BACKGROUND Homologous recombination (HR) repair deficiency arising from defects in BRCA1 or BRCA2 is associated with characteristic patterns of somatic mutations. In this genetic study, we ask whether inactivating mutations in further genes of the HR pathway or the DNA damage checkpoint also give rise to somatic mutation patterns that can be used for treatment prediction. RESULTS Using whole genome sequencing of an isogenic knockout cell line panel, we find a universal HR deficiency-specific base substitution signature that is similar to COSMIC signature 3. In contrast, we detect different deletion phenotypes corresponding to specific HR mutants. The inactivation of BRCA2 or PALB2 leads to larger deletions, typically with microhomology, when compared to the disruption of BRCA1, RAD51 paralogs, or RAD54. Comparison with the deletion spectrum of Cas9 cut sites suggests that most spontaneously arising genomic deletions are not the consequence of double-strand breaks. Surprisingly, the inactivation of checkpoint kinases ATM and CHK2 has no mutagenic consequences. Analysis of tumor exomes with biallelic inactivating mutations in the investigated genes confirms the validity of the cell line models. We present a comprehensive analysis of sensitivity of the investigated mutants to 13 therapeutic agents for the purpose of correlating genomic mutagenic phenotypes with drug sensitivity. CONCLUSION Our results suggest that no single genomic mutational class shows perfect correlation with sensitivity to common treatments, but the contribution of COSMIC signature 3 to base substitutions, or a combined measure of different features, may be reasonably good at predicting platinum and PARP inhibitor sensitivity.
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Affiliation(s)
- Ádám Póti
- Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar tudosok krt 2, Budapest, H-1117, Hungary
| | - Hella Gyergyák
- Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar tudosok krt 2, Budapest, H-1117, Hungary
| | - Eszter Németh
- Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar tudosok krt 2, Budapest, H-1117, Hungary
| | - Orsolya Rusz
- Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar tudosok krt 2, Budapest, H-1117, Hungary
- Department of Oncotherapy, University of Szeged, Szeged, Hungary
| | - Szilárd Tóth
- Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar tudosok krt 2, Budapest, H-1117, Hungary
| | - Csenger Kovácsházi
- Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar tudosok krt 2, Budapest, H-1117, Hungary
| | - Dan Chen
- Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar tudosok krt 2, Budapest, H-1117, Hungary
| | - Bernadett Szikriszt
- Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar tudosok krt 2, Budapest, H-1117, Hungary
| | - Sándor Spisák
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA, 02215, USA
- Center for Functional Cancer Epigenetics, Dana-Farber Cancer Institute, Boston, MA, 02215, USA
| | - Shunichi Takeda
- Department of Radiation Genetics, Kyoto University Medical School, Kyoto, 606-8501, Japan
| | - Gergely Szakács
- Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar tudosok krt 2, Budapest, H-1117, Hungary
- Institute of Cancer Research, Medical University Vienna, Vienna, Austria
| | - Zoltan Szallasi
- Computational Health Informatics Program (CHIP), Boston Children's Hospital, Boston, MA, USA
- Harvard Medical School, Boston, MA, USA
- Danish Cancer Society Research Center, Copenhagen, Denmark
- SE-NAP, Brain Metastasis Research Group, 2nd Department of Pathology, Semmelweis University, Budapest, Hungary
| | | | - Dávid Szüts
- Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar tudosok krt 2, Budapest, H-1117, Hungary.
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8
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Huang L, Xia B, Shi X, Gao J, Yang Y, Xu F, Qi F, Liang C, Huang J, Luo Z. Time-restricted release of multiple neurotrophic factors promotes axonal regeneration and functional recovery after peripheral nerve injury. FASEB J 2019; 33:8600-8613. [PMID: 30995417 DOI: 10.1096/fj.201802065rr] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Delivery of multiple neurotrophic factors (NTFs), especially with time-restricted release kinetics, holds great potential for nerve repair. In this study, we utilized the tetracycline-regulatable Tet-On 3G system to control the expression of c-Jun, which is a common regulator of multiple NTFs in Schwann cells (SCs). In vitro, Tet-On/c-Jun-modified SCs showed a tightly controllable secretion of multiple NTFs, including glial cell line-derived NTF, nerve growth factor, brain-derived NTF, and artemin, by the addition or removal of doxycycline (Dox). When Tet-On/c-Jun-transduced SCs were grafted in vivo, the expression of NTFs could also be regulated by oral administration or removal of Dox. Fluoro-Gold retrograde tracing results indicated that a biphasic NTF expression scheme (Dox+3/-9, NTFs were up-regulated for 3 wk and declined to physiologic levels for another 9 wk) achieved more axonal regeneration than continuous up-regulation of NTFs (Dox+12) or no NTF induction (Dox-12). More importantly, the Dox+3/-9-group animals showed much better functional recovery than the animals in the Dox+12 and Dox-12 groups. Our findings, for the first time, demonstrated drug-controllable expression of multiple NTFs in nerve repair cells both in vitro and in vivo. These findings provide new hope for developing an optimal therapeutic alternative for nerve repair through the time-restricted release of multiple NTFs using Tet-On/c-Jun-modified SCs.-Huang, L., Xia, B., Shi, X., Gao, J., Yang, Y., Xu, F., Qi, F., Liang, C., Huang, J., Luo, Z. Time-restricted release of multiple neurotrophic factors promotes axonal regeneration and functional recovery after peripheral nerve injury.
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Affiliation(s)
- Liangliang Huang
- Department of Orthopaedics, Xijing Hospital, The Fourth Military Medical University, Xi'an, China.,Department of Orthopaedics, General Hospital of Central Theater Command of People's Liberation Army, Wuhan, China
| | - Bing Xia
- Department of Orthopaedics, Xijing Hospital, The Fourth Military Medical University, Xi'an, China
| | - Xiaowei Shi
- Department of Orthopaedics, Xijing Hospital, The Fourth Military Medical University, Xi'an, China
| | - Jianbo Gao
- Department of Orthopaedics, Xijing Hospital, The Fourth Military Medical University, Xi'an, China
| | - Yujie Yang
- Department of Orthopaedics, Xijing Hospital, The Fourth Military Medical University, Xi'an, China
| | - Feng Xu
- Department of Orthopaedics, General Hospital of Central Theater Command of People's Liberation Army, Wuhan, China
| | - Fengyu Qi
- Department of Orthopaedics, General Hospital of Central Theater Command of People's Liberation Army, Wuhan, China
| | - Chao Liang
- Department of Orthopaedics, Xijing Hospital, The Fourth Military Medical University, Xi'an, China
| | - Jinghui Huang
- Department of Orthopaedics, Xijing Hospital, The Fourth Military Medical University, Xi'an, China
| | - Zhuojing Luo
- Department of Orthopaedics, Xijing Hospital, The Fourth Military Medical University, Xi'an, China
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9
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Peng B, Ortega J, Gu L, Chang Z, Li GM. Phosphorylation of proliferating cell nuclear antigen promotes cancer progression by activating the ATM/Akt/GSK3β/Snail signaling pathway. J Biol Chem 2019; 294:7037-7045. [PMID: 30858175 DOI: 10.1074/jbc.ra119.007897] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2019] [Revised: 03/03/2019] [Indexed: 12/19/2022] Open
Abstract
Proliferating cell nuclear antigen (PCNA) and its posttranslational modifications regulate DNA metabolic reactions, including DNA replication and repair, at replication forks. PCNA phosphorylation at Tyr-211 (PCNA-Y211p) inhibits DNA mismatch repair and induces misincorporation during DNA synthesis. Here, we describe an unexpected role of PCNA-Y211p in cancer promotion and development. Cells expressing phosphorylation-mimicking PCNA, PCNA-Y211D, show elevated hallmarks specific to the epithelial-mesenchymal transition (EMT), including the up-regulation of the EMT-promoting factor Snail and the down-regulation of EMT-inhibitory factors E-cadherin and GSK3β. The PCNA-Y211D-expressing cells also exhibited active cell migration and underwent G2/M arrest. Interestingly, all of these EMT-associated activities required the activation of ATM and Akt kinases, as inactivating these protein kinases by gene knockdown or inhibitors blocked EMT-associated signaling and cell migration. We concluded that PCNA phosphorylation promotes cancer progression via the ATM/Akt/GSK3β/Snail signaling pathway. In conclusion, this study identifies a novel PCNA function and reveals the molecular basis of phosphorylated PCNA-mediated cancer development and progression.
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Affiliation(s)
- Bo Peng
- From the Department of Basic Medical Sciences, Tsinghua University School of Medicine, Beijing, China 100084 and
| | - Janice Ortega
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Liya Gu
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Zhijie Chang
- From the Department of Basic Medical Sciences, Tsinghua University School of Medicine, Beijing, China 100084 and
| | - Guo-Min Li
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, Texas 75390
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10
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AND-1 fork protection function prevents fork resection and is essential for proliferation. Nat Commun 2018; 9:3091. [PMID: 30082684 PMCID: PMC6079002 DOI: 10.1038/s41467-018-05586-7] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Accepted: 07/13/2018] [Indexed: 12/31/2022] Open
Abstract
AND-1/Ctf4 bridges the CMG helicase and DNA polymerase alpha, facilitating replication. Using an inducible degron system in avian cells, we find that AND-1 depletion is incompatible with proliferation, owing to cells accumulating in G2 with activated DNA damage checkpoint. Replication without AND-1 causes fork speed slow-down and accumulation of long single-stranded DNA (ssDNA) gaps at the replication fork junction, with these regions being converted to DNA double strand breaks (DSBs) in G2. Strikingly, resected forks and DNA damage accumulation in G2, but not fork slow-down, are reverted by treatment with mirin, an MRE11 nuclease inhibitor. Domain analysis of AND-1 further revealed that the HMG box is important for fast replication but not for proliferation, whereas conversely, the WD40 domain prevents fork resection and subsequent DSB-associated lethality. Thus, our findings uncover a fork protection function of AND-1/Ctf4 manifested via the WD40 domain that is essential for proliferation and averts genome instability. AND-1, the vertebrate orthologue of Ctf4, is a critical player during DNA replication and for maintenance of genome integrity. Here the authors use a conditional AND-1 depletion system in avian DT40 cells to reveal the consequences of the lack of AND-1 on cell proliferation and DNA replication.
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11
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Warsaw breakage syndrome DDX11 helicase acts jointly with RAD17 in the repair of bulky lesions and replication through abasic sites. Proc Natl Acad Sci U S A 2018; 115:8412-8417. [PMID: 30061412 PMCID: PMC6099846 DOI: 10.1073/pnas.1803110115] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
Warsaw breakage syndrome, a developmental disorder caused by mutations in the conserved DDX11/ChlR1 DNA helicase, shows features of genome instability partly overlapping with those of Fanconi anemia (FA). Here, using avian cellular models of DDX11 deficiency, we find that DDX11 functions as backup to the FA pathway and facilitates, jointly with the checkpoint clamp 9-1-1, a homologous recombination pathway of DNA bulky-lesion repair that does not affect replication fork speed and stalled fork stability. DDX11 also promotes diversification of the immunoglobulin-variable gene locus by facilitating hypermutation and gene conversion at programmed abasic sites that constitute endogenous replication blocks. The results suggest commonality between postreplicative gap filling and replication through abasic sites and pinpoint DDX11 as a critical player in both these processes. Warsaw breakage syndrome, a developmental disorder caused by mutations in the DDX11/ChlR1 helicase, shows cellular features of genome instability similar to Fanconi anemia (FA). Here we report that DDX11-deficient avian DT40 cells exhibit interstrand crosslink (ICL)-induced chromatid breakage, with DDX11 functioning as backup for the FA pathway in regard to ICL repair. Importantly, we establish that DDX11 acts jointly with the 9-1-1 checkpoint clamp and its loader, RAD17, primarily in a postreplicative fashion, to promote homologous recombination repair of bulky lesions, but is not required for intra-S checkpoint activation or efficient fork progression. Notably, we find that DDX11 also promotes diversification of the chicken Ig-variable gene, a process triggered by programmed abasic sites, by facilitating both hypermutation and homeologous recombination-mediated gene conversion. Altogether, our results uncover that DDX11 orchestrates jointly with 9-1-1 and its loader, RAD17, DNA damage tolerance at sites of bulky lesions, and endogenous abasic sites. These functions may explain the essential roles of DDX11 and its similarity with 9-1-1 during development.
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12
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Nakazato A, Kajita K, Ooka M, Akagawa R, Abe T, Takeda S, Branzei D, Hirota K. SPARTAN promotes genetic diversification of the immunoglobulin-variable gene locus in avian DT40 cells. DNA Repair (Amst) 2018; 68:50-57. [PMID: 29935364 DOI: 10.1016/j.dnarep.2018.06.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Revised: 06/12/2018] [Accepted: 06/13/2018] [Indexed: 11/17/2022]
Abstract
Prolonged replication arrest on damaged templates is a cause of fork collapse, potentially resulting in genome instability. Arrested replication is rescued by translesion DNA synthesis (TLS) and homologous recombination (HR)-mediated template switching. SPARTAN, a ubiquitin-PCNA-interacting regulator, regulates TLS via mechanisms incompletely understood. Here we show that SPARTAN promotes diversification of the chicken DT40 immunoglobulin-variable λ gene by facilitating TLS-mediated hypermutation and template switch-mediated gene-conversion, both induced by replication blocks at abasic sites. SPARTAN-/- and SPARTAN-/-/Polη-/-/Polζ-/- cells showed defective and similar decrease in hypermutation rates, as well as alterations in the mutation spectra, with decreased dG-to-dC transversions and increased dG-to-dA transitions. Strikingly, SPARTAN-/- cells also showed reduced template switch-mediated gene-conversion at the immunoglobulin locus, while being proficient in HR-mediated double strand break repair, and sister chromatid recombination. Notably, SPARTAN's ubiquitin-binding zinc-finger 4 domain, but not the PCNA interacting peptide domain or its DNA-binding domain, was specifically required for the promotion of immunoglobulin gene-conversion, while all these three domains were shown to contribute similarly to TLS. In all, our results suggest that SPARTAN mediates TLS in concert with the Polη-Polζ pathway and that it facilitates HR-mediated template switching at a subset of stalled replication forks, potentially by interacting with unknown ubiquitinated proteins.
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Affiliation(s)
- Arisa Nakazato
- Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Minamiosawa 1-1, Hachioji-shi, Tokyo, 192-0397, Japan
| | - Kinumi Kajita
- Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Minamiosawa 1-1, Hachioji-shi, Tokyo, 192-0397, Japan
| | - Masato Ooka
- Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Minamiosawa 1-1, Hachioji-shi, Tokyo, 192-0397, Japan
| | - Remi Akagawa
- Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Yoshidakonoe, Sakyo-ku, Kyoto, 606-8501, Japan
| | - Takuya Abe
- Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Minamiosawa 1-1, Hachioji-shi, Tokyo, 192-0397, Japan; IFOM, The FIRC Institute of Molecular Oncology, Via Adamello 16, 20139 Milan, Italy
| | - Shunichi Takeda
- Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Yoshidakonoe, Sakyo-ku, Kyoto, 606-8501, Japan
| | - Dana Branzei
- IFOM, The FIRC Institute of Molecular Oncology, Via Adamello 16, 20139 Milan, Italy; Istituto di Genetica Molecolare, Consiglio Nazionale delle Ricerche (IGM-CNR), Via Abbiategrasso 207, 27100, Pavia, Italy.
| | - Kouji Hirota
- Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Minamiosawa 1-1, Hachioji-shi, Tokyo, 192-0397, Japan.
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13
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Trenner A, Godau J, Sartori AA. A Short BRCA2-Derived Cell-Penetrating Peptide Targets RAD51 Function and Confers Hypersensitivity toward PARP Inhibition. Mol Cancer Ther 2018; 17:1392-1404. [PMID: 29654063 DOI: 10.1158/1535-7163.mct-17-1156] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Revised: 03/01/2018] [Accepted: 04/04/2018] [Indexed: 11/16/2022]
Abstract
Under conditions of genotoxic stress, cancer cells strongly rely on efficient DNA repair to survive and proliferate. The human BRCA2 tumor suppressor protein is indispensable for the repair of DNA double-strand breaks by homologous recombination (HR) by virtue of its ability to promote RAD51 loading onto single-stranded DNA. Therefore, blocking the interaction between BRCA2 and RAD51 could significantly improve the efficacy of conventional anticancer therapies. However, targeting protein-protein interaction (PPI) interfaces has proven challenging because flat and large PPI surfaces generally do not support binding of small-molecule inhibitors. In contrast, peptides are more potent for targeting PPIs but are otherwise difficult to deliver into cells. Here, we report that a synthetic 16-mer peptide derived from the BRC4 repeat motif of BRCA2 is capable of blocking RAD51 binding to BRCA2. Efficient noncytotoxic cellular uptake of a nona-arginine (R9)-conjugated version of the BRC4 peptide interferes with DNA damage-induced RAD51 foci formation and HR. Moreover, transduction of the BRC4 peptide impairs replication fork-protective function of BRCA2 and triggers MRE11-dependent degradation of nascent DNA in response to DNA replication stress. Finally, the BRC4 cell-penetrating peptide (CPP) confers selective hypersensitivity to PARP inhibition in cancer cells but spares noncancerous cells. Taken together, our data highlight an innovative approach to develop novel peptide-based DNA repair inhibitors and establish BRCA2-derived CPPs as promising anticancer agents. Mol Cancer Ther; 17(7); 1392-404. ©2018 AACR.
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Affiliation(s)
- Anika Trenner
- Institute of Molecular Cancer Research, University of Zurich, Zurich, Switzerland
| | - Julia Godau
- Institute of Molecular Cancer Research, University of Zurich, Zurich, Switzerland
| | - Alessandro A Sartori
- Institute of Molecular Cancer Research, University of Zurich, Zurich, Switzerland.
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14
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Abe T, Kawasumi R, Arakawa H, Hori T, Shirahige K, Losada A, Fukagawa T, Branzei D. Chromatin determinants of the inner-centromere rely on replication factors with functions that impart cohesion. Oncotarget 2018; 7:67934-67947. [PMID: 27636994 PMCID: PMC5356530 DOI: 10.18632/oncotarget.11982] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Accepted: 09/06/2016] [Indexed: 01/08/2023] Open
Abstract
Replication fork-associated factors promote genome integrity and protect against cancer. Mutations in the DDX11 helicase and the ESCO2 acetyltransferase also cause related developmental disorders classified as cohesinopathies. Here we generated vertebrate model cell lines of these disorders and cohesinopathies-related genes. We found that vertebrate DDX11 and Tim-Tipin are individually needed to compensate for ESCO2 loss in chromosome segregation, with DDX11 also playing complementary roles with ESCO2 in centromeric cohesion. Our study reveals that overt centromeric cohesion loss does not necessarily precede chromosome missegregation, while both these problems correlate with, and possibly originate from, inner-centromere defects involving reduced phosphorylation of histone H3T3 (pH3T3) in the region. Interestingly, the mitotic pH3T3 mark was defective in all analyzed replication-related mutants with functions in cohesion. The results pinpoint mitotic pH3T3 as a postreplicative chromatin mark that is sensitive to replication stress and conducts with different kinetics to robust centromeric cohesion and correct chromosome segregation.
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Affiliation(s)
- Takuya Abe
- IFOM, The FIRC Institute for Molecular Oncology Foundation, Milan, Italy
| | - Ryotaro Kawasumi
- IFOM, The FIRC Institute for Molecular Oncology Foundation, Milan, Italy.,Department of Chemistry, Graduate School of Science and Engineering, Tokyo Metropolitan University, Minamiosawa, Hachioji-shi, Tokyo, Japan
| | - Hiroshi Arakawa
- IFOM, The FIRC Institute for Molecular Oncology Foundation, Milan, Italy
| | - Tetsuya Hori
- Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka, Japan
| | - Katsuhiko Shirahige
- Laboratory of Genome Structure and Function, Research Center for Epigenetic Disease, Institute of Molecular and Cellular Biosciences, University of Tokyo, Yayoi Bunkyo-Ku, Tokyo, Japan
| | - Ana Losada
- Chromosome Dynamics Group, Molecular Oncology Program, Spanish National Cancer Research Centre, Madrid, Spain
| | - Tatsuo Fukagawa
- Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka, Japan
| | - Dana Branzei
- IFOM, The FIRC Institute for Molecular Oncology Foundation, Milan, Italy
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15
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Kawasumi R, Abe T, Arakawa H, Garre M, Hirota K, Branzei D. ESCO1/2's roles in chromosome structure and interphase chromatin organization. Genes Dev 2017; 31:2136-2150. [PMID: 29196537 PMCID: PMC5749162 DOI: 10.1101/gad.306084.117] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Accepted: 11/09/2017] [Indexed: 11/24/2022]
Abstract
In this study, Kawasumi et al. researched how ESCO1/2 acetyltransferases mediating SMC3 acetylation and sister chromatid cohesion (SCC) interact and contribute to chromosome structure and proliferation. Using chicken DT40 cell lines with mutations in ESCO1/2, SMC3 acetylation, and the cohesin remover WAPL, they show that cohesion establishment by vertebrate ESCO1/2 is linked to interphase chromatin architecture formation. ESCO1/2 acetyltransferases mediating SMC3 acetylation and sister chromatid cohesion (SCC) are differentially required for genome integrity and development. Here we established chicken DT40 cell lines with mutations in ESCO1/2, SMC3 acetylation, and the cohesin remover WAPL. Both ESCO1 and ESCO2 promoted SCC, while ESCO2 was additionally and specifically required for proliferation and centromere integrity. ESCO1 overexpression fully suppressed the slow proliferation and centromeric separation phenotypes of esco2 cells but only partly suppressed its chromosome arm SCC defects. Concomitant inactivation of ESCO1 and ESCO2 caused lethality owing to compromised mitotic chromosome segregation. Neither wapl nor acetyl-mimicking smc3-QQ mutations rescued esco1 esco2 lethality. Notably, esco1 esco2 wapl conditional mutants showed very severe proliferation defects associated with catastrophic mitoses and also abnormal interphase chromatin organization patterns. The results indicate that cohesion establishment by vertebrate ESCO1/2 is linked to interphase chromatin architecture formation, a newly identified function of cohesin acetyltransferases that is both fundamentally and medically relevant.
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Affiliation(s)
- Ryotaro Kawasumi
- The FIRC (Italian Foundation for Cancer Research) Institute of Molecular Oncology (IFOM), 20139 Milan, Italy
| | - Takuya Abe
- The FIRC (Italian Foundation for Cancer Research) Institute of Molecular Oncology (IFOM), 20139 Milan, Italy.,Department of Chemistry, Graduate School of Science and Engineering, Tokyo Metropolitan University, Hachioji-shi, Tokyo 192-0397, Japan
| | - Hiroshi Arakawa
- The FIRC (Italian Foundation for Cancer Research) Institute of Molecular Oncology (IFOM), 20139 Milan, Italy
| | - Massimiliano Garre
- The FIRC (Italian Foundation for Cancer Research) Institute of Molecular Oncology (IFOM), 20139 Milan, Italy
| | - Kouji Hirota
- Department of Chemistry, Graduate School of Science and Engineering, Tokyo Metropolitan University, Hachioji-shi, Tokyo 192-0397, Japan
| | - Dana Branzei
- The FIRC (Italian Foundation for Cancer Research) Institute of Molecular Oncology (IFOM), 20139 Milan, Italy.,Istituto di Genetica Molecolare, Consiglio Nazionale delle Ricerche (IGM-CNR), 27100 Pavia, Italy
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16
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Bastianello G, Arakawa H. A double-strand break can trigger immunoglobulin gene conversion. Nucleic Acids Res 2016; 45:231-243. [PMID: 27701075 PMCID: PMC5224512 DOI: 10.1093/nar/gkw887] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2016] [Revised: 09/22/2016] [Accepted: 09/26/2016] [Indexed: 12/23/2022] Open
Abstract
All three B cell-specific activities of the immunoglobulin (Ig) gene re-modeling system—gene conversion, somatic hypermutation and class switch recombination—require activation-induced deaminase (AID). AID-induced DNA lesions must be further processed and dissected into different DNA recombination pathways. In order to characterize potential intermediates for Ig gene conversion, we inserted an I-SceI recognition site into the complementarity determining region 1 (CDR1) of the Ig light chain locus of the AID knockout DT40 cell line, and conditionally expressed I-SceI endonuclease. Here, we show that a double-strand break (DSB) in CDR1 is sufficient to trigger Ig gene conversion in the absence of AID. The pattern and pseudogene usage of DSB-induced gene conversion were comparable to those of AID-induced gene conversion; surprisingly, sometimes a single DSB induced multiple gene conversion events. These constitute direct evidence that a DSB in the V region can be an intermediate for gene conversion. The fate of the DNA lesion downstream of a DSB had more flexibility than that of AID, suggesting two alternative models: (i) DSBs during the physiological gene conversion are in the minority compared to single-strand breaks (SSBs), which are frequently generated following DNA deamination, or (ii) the physiological gene conversion is mediated by a tightly regulated DSB that is locally protected from non-homologous end joining (NHEJ) or other non-homologous DNA recombination machineries.
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Affiliation(s)
- Giulia Bastianello
- IFOM - FIRC Institute of Molecular Oncology Foundation, Via Adamello 16, 20139 Milan, Italy.,Università degli Studi di Milano, Dipartimento di Bioscienze, Via Celoria 26, 20133 Milan, Italy
| | - Hiroshi Arakawa
- IFOM - FIRC Institute of Molecular Oncology Foundation, Via Adamello 16, 20139 Milan, Italy
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17
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Martinez JS, Baldeyron C, Carreira A. Molding BRCA2 function through its interacting partners. Cell Cycle 2016; 14:3389-95. [PMID: 26566862 DOI: 10.1080/15384101.2015.1093702] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The role of the tumor suppressor BRCA2 has been shaped over 2 decades thanks to the discovery of its protein and nucleic acid partners, biochemical and structural studies of the protein, and the functional evaluation of germline variants identified in breast cancer patients. Yet, the pathogenic and functional effect of many germline mutations in BRCA2 remains undetermined, and the heterogeneity of BRCA2-associated tumors challenges the identification of causative variants that drive tumorigenesis. In this review, we propose an overview of the established and emerging interacting partners and functional pathways attributed to BRCA2, and we speculate on how variants altering these functions may contribute to cancer susceptibility.
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Affiliation(s)
- Juan S Martinez
- a Institut Curie; Centre de Recherche ; Orsay , France.,b CNRS UMR3348; Genotoxic Stress and Cancer; Centre Universitaire ; Orsay , France
| | - Céline Baldeyron
- a Institut Curie; Centre de Recherche ; Orsay , France.,b CNRS UMR3348; Genotoxic Stress and Cancer; Centre Universitaire ; Orsay , France
| | - Aura Carreira
- a Institut Curie; Centre de Recherche ; Orsay , France.,b CNRS UMR3348; Genotoxic Stress and Cancer; Centre Universitaire ; Orsay , France
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