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McCarthy-Leo CE, Brush GS, Pique-Regi R, Luca F, Tainsky MA, Finley RL. Comprehensive analysis of the functional impact of single nucleotide variants of human CHEK2. PLoS Genet 2024; 20:e1011375. [PMID: 39146382 PMCID: PMC11349238 DOI: 10.1371/journal.pgen.1011375] [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: 01/07/2024] [Revised: 08/27/2024] [Accepted: 07/25/2024] [Indexed: 08/17/2024] Open
Abstract
Loss of function mutations in the checkpoint kinase gene CHEK2 are associated with increased risk of breast and other cancers. Most of the 3,188 unique amino acid changes that can result from non-synonymous single nucleotide variants (SNVs) of CHEK2, however, have not been tested for their impact on the function of the CHEK2-enocded protein (CHK2). One successful approach to testing the function of variants has been to test for their ability to complement mutations in the yeast ortholog of CHEK2, RAD53. This approach has been used to provide functional information on over 100 CHEK2 SNVs and the results align with functional assays in human cells and known pathogenicity. Here we tested all but two of the 4,887 possible SNVs in the CHEK2 open reading frame for their ability to complement RAD53 mutants using a high throughput technique of deep mutational scanning (DMS). Among the non-synonymous changes, 770 were damaging to protein function while 2,417 were tolerated. The results correlate well with previous structure and function data and provide a first or additional functional assay for all the variants of uncertain significance identified in clinical databases. Combined, this approach can be used to help predict the pathogenicity of CHEK2 variants of uncertain significance that are found in susceptibility screening and could be applied to other cancer risk genes.
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Affiliation(s)
- Claire E. McCarthy-Leo
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, Michigan, United States of America
| | - George S. Brush
- Department of Oncology, Molecular Therapeutics Program, Barbara Ann Karmanos Cancer Institute, Wayne State University School of Medicine, Detroit, Michigan, United States of America
| | - Roger Pique-Regi
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, Michigan, United States of America
- Department of Obstetrics and Gynecology, Wayne State University School of Medicine, Detroit, Michigan, United States of America
| | - Francesca Luca
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, Michigan, United States of America
- Department of Obstetrics and Gynecology, Wayne State University School of Medicine, Detroit, Michigan, United States of America
| | - Michael A. Tainsky
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, Michigan, United States of America
- Department of Oncology, Molecular Therapeutics Program, Barbara Ann Karmanos Cancer Institute, Wayne State University School of Medicine, Detroit, Michigan, United States of America
| | - Russell L. Finley
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, Michigan, United States of America
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2
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Medina-Suárez S, Ayra-Plasencia J, Pérez-Martínez L, Butter F, Machín F. Msc1 is a nuclear envelope protein that reinforces DNA repair in late mitosis. iScience 2024; 27:110250. [PMID: 39021806 PMCID: PMC11253511 DOI: 10.1016/j.isci.2024.110250] [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: 12/11/2023] [Revised: 04/15/2024] [Accepted: 06/08/2024] [Indexed: 07/20/2024] Open
Abstract
Precise double-strand break (DSB) repair is a paramount for genome stability. Homologous recombination (HR) repairs DSBs when cyclin-dependent kinase (CDK) activity is high, which correlates with the availability of the sister chromatid as a template. However, anaphase and telophase are paradoxical scenarios since high CDK favors HR despite sister chromatids being no longer aligned. To identify factors specifically involved in DSB repair in late mitosis, we have undertaken comparative proteomics in Saccharomyces cerevisiae and found that meiotic sister chromatid 1 (Msc1), a poorly characterized nuclear envelope protein, is significantly enriched upon both random and guided DSBs. We further show that Δmsc1 is more sensitive to DSBs in late mitosis, and has a delayed repair of DBSs, as indicated by increased Rad53 hyperphosphorylation, a higher presence of RPA foci, fewer Rad52 repair factories, and slower HR completion. We propose that Msc1 favors the later stages of HR and the timely completion of DSB repair before cytokinesis.
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Affiliation(s)
- Sara Medina-Suárez
- Unidad de Investigación, Hospital Universitario Nuestra Señora de Candelaria, 38010 Santa Cruz de Tenerife, Spain
- Instituto de Tecnologías Biomédicas, Universidad de La Laguna, 38200 San Cristóbal de La Laguna, Spain
| | - Jessel Ayra-Plasencia
- Unidad de Investigación, Hospital Universitario Nuestra Señora de Candelaria, 38010 Santa Cruz de Tenerife, Spain
- Instituto de Tecnologías Biomédicas, Universidad de La Laguna, 38200 San Cristóbal de La Laguna, Spain
| | | | - Falk Butter
- Institute of Molecular Biology (IMB), 55128 Mainz, Germany
- Institute of Molecular Virology and Cell Biology, Friedrich Loeffler Institute, 17493 Greifswald, Germany
| | - Félix Machín
- Unidad de Investigación, Hospital Universitario Nuestra Señora de Candelaria, 38010 Santa Cruz de Tenerife, Spain
- Instituto de Tecnologías Biomédicas, Universidad de La Laguna, 38200 San Cristóbal de La Laguna, Spain
- Facultad de Ciencias de la Salud, Universidad Fernando Pessoa Canarias, 35450 Las Palmas de Gran Canaria, Spain
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3
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Zhang Y, Cai H, Chen R, Feng J. DNA Damage Checkpoints Govern Global Gene Transcription and Exhibit Species-Specific Regulation on HOF1 in Candida albicans. J Fungi (Basel) 2024; 10:387. [PMID: 38921373 PMCID: PMC11204775 DOI: 10.3390/jof10060387] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2024] [Revised: 05/25/2024] [Accepted: 05/27/2024] [Indexed: 06/27/2024] Open
Abstract
DNA damage checkpoints are essential for coordinating cell cycle arrest and gene transcription during DNA damage response. Exploring the targets of checkpoint kinases in Saccharomyces cerevisiae and other fungi has expanded our comprehension of the downstream pathways involved in DNA damage response. While the function of checkpoint kinases, specifically Rad53, is well documented in the fungal pathogen Candida albicans, their targets remain poorly understood. In this study, we explored the impact of deleting RAD53 on the global transcription profiles and observed alterations in genes associated with ribosome biogenesis, DNA replication, and cell cycle. However, the deletion of RAD53 only affected a limited number of known DNA damage-responsive genes, including MRV6 and HMX1. Unlike S. cerevisiae, the downregulation of HOF1 transcription in C. albicans under the influence of Methyl Methanesulfonate (MMS) did not depend on Dun1 but still relied on Rad53 and Rad9. In addition, the transcription factor Mcm1 was identified as a regulator of HOF1 transcription, with evidence of dynamic binding to its promoter region; however, this dynamic binding was interrupted following the deletion of RAD53. Furthermore, Rad53 was observed to directly interact with the promoter region of HOF1, thus suggesting a potential role in governing its transcription. Overall, checkpoints regulate global gene transcription in C. albicans and show species-specific regulation on HOF1; these discoveries improve our understanding of the signaling pathway related to checkpoints in this pathogen.
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Affiliation(s)
| | | | | | - Jinrong Feng
- Department of Pathogen Biology, School of Medicine, Nantong University, Nantong 226007, China; (Y.Z.); (H.C.); (R.C.)
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4
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Leite AC, Costa V, Pereira C. Mitochondria and the cell cycle in budding yeast. Int J Biochem Cell Biol 2023; 161:106444. [PMID: 37419443 DOI: 10.1016/j.biocel.2023.106444] [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: 03/10/2023] [Revised: 06/05/2023] [Accepted: 07/03/2023] [Indexed: 07/09/2023]
Abstract
As centers for energy production and essential biosynthetic activities, mitochondria are vital for cell growth and proliferation. Accumulating evidence suggests an integrated regulation of these organelles and the nuclear cell cycle in distinct organisms. In budding yeast, a well-established example of this coregulation is the coordinated movement and positional control of mitochondria during the different phases of the cell cycle. The molecular determinants involved in the inheritance of the fittest mitochondria by the bud also seem to be cell cycle-regulated. In turn, loss of mtDNA or defects in mitochondrial structure or inheritance often lead to a cell cycle delay or arrest, indicating that mitochondrial function can also regulate cell cycle progression, possibly through the activation of cell cycle checkpoints. The up-regulation of mitochondrial respiration at G2/M, presumably to fulfil energetic requirements for progression at this phase, also supports a mitochondria-cell cycle interplay. Cell cycle-linked mitochondrial regulation is accomplished at the transcription level and through post-translational modifications, predominantly protein phosphorylation. Here, we address mitochondria-cell cycle interactions in the yeast Saccharomyces cerevisiae and discuss future challenges in the field.
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Affiliation(s)
- Ana Cláudia Leite
- i3S, Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Portugal; IBMC, Instituto de Biologia Celular e Molecular, Universidade do Porto, Portugal; ICBAS, Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Portugal
| | - Vítor Costa
- i3S, Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Portugal; IBMC, Instituto de Biologia Celular e Molecular, Universidade do Porto, Portugal; ICBAS, Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Portugal
| | - Clara Pereira
- i3S, Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Portugal; IBMC, Instituto de Biologia Celular e Molecular, Universidade do Porto, Portugal.
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5
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A review on regulation of cell cycle by extracellular matrix. Int J Biol Macromol 2023; 232:123426. [PMID: 36708893 DOI: 10.1016/j.ijbiomac.2023.123426] [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: 11/15/2022] [Revised: 01/12/2023] [Accepted: 01/21/2023] [Indexed: 01/26/2023]
Abstract
The extracellular matrix (ECM) is a network of structural proteins, glycoproteins and proteoglycans that assists independent cells in aggregating and forming highly organized functional structures. ECM serves numerous purposes and is an essential component of tissue structure and functions. Initially, the role of ECM was considered to be confined to passive functions like providing mechanical strength and structural identity to tissues, serving as barriers and platforms for cells. The doors to understanding ECM's proper role in tissue functioning opened with the discovery of cellular receptors, integrins to which ECM components binds and influences cellular activities. Understanding and utilizing ECM's potential to control cellular function has become a topic of much interest in recent decades, providing different outlooks to study processes involved in developmental programs, wound healing and tumour progression. On another front, the regulatory mechanisms operating to prevent errors in the cell cycle have been topics of a titanic amount of studies. This is expected as many diseases, most infamously cancer, are associated with defects in their functioning. This review focuses on how ECM, through different methods, influences the progression of the somatic cell cycle and provides deeper insights into molecular mechanisms of functional communication between adhesion complex, signalling pathways and cell cycle machinery.
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6
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Vanderwaeren L, Dok R, Voordeckers K, Nuyts S, Verstrepen KJ. Saccharomyces cerevisiae as a Model System for Eukaryotic Cell Biology, from Cell Cycle Control to DNA Damage Response. Int J Mol Sci 2022; 23:11665. [PMID: 36232965 PMCID: PMC9570374 DOI: 10.3390/ijms231911665] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Revised: 09/26/2022] [Accepted: 09/28/2022] [Indexed: 11/08/2022] Open
Abstract
The yeast Saccharomyces cerevisiae has been used for bread making and beer brewing for thousands of years. In addition, its ease of manipulation, well-annotated genome, expansive molecular toolbox, and its strong conservation of basic eukaryotic biology also make it a prime model for eukaryotic cell biology and genetics. In this review, we discuss the characteristics that made yeast such an extensively used model organism and specifically focus on the DNA damage response pathway as a prime example of how research in S. cerevisiae helped elucidate a highly conserved biological process. In addition, we also highlight differences in the DNA damage response of S. cerevisiae and humans and discuss the challenges of using S. cerevisiae as a model system.
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Affiliation(s)
- Laura Vanderwaeren
- Laboratory of Experimental Radiotherapy, Department of Oncology, KU Leuven, 3000 Leuven, Belgium
- Laboratory of Genetics and Genomics, Centre for Microbial and Plant Genetics, Department M2S, KU Leuven, 3001 Leuven, Belgium
- Laboratory for Systems Biology, VIB-KU Leuven Center for Microbiology, 3001 Leuven, Belgium
| | - Rüveyda Dok
- Laboratory of Experimental Radiotherapy, Department of Oncology, KU Leuven, 3000 Leuven, Belgium
| | - Karin Voordeckers
- Laboratory of Genetics and Genomics, Centre for Microbial and Plant Genetics, Department M2S, KU Leuven, 3001 Leuven, Belgium
- Laboratory for Systems Biology, VIB-KU Leuven Center for Microbiology, 3001 Leuven, Belgium
| | - Sandra Nuyts
- Laboratory of Experimental Radiotherapy, Department of Oncology, KU Leuven, 3000 Leuven, Belgium
- Department of Radiation Oncology, Leuven Cancer Institute, University Hospitals Leuven, 3000 Leuven, Belgium
| | - Kevin J. Verstrepen
- Laboratory of Genetics and Genomics, Centre for Microbial and Plant Genetics, Department M2S, KU Leuven, 3001 Leuven, Belgium
- Laboratory for Systems Biology, VIB-KU Leuven Center for Microbiology, 3001 Leuven, Belgium
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7
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Pizzul P, Casari E, Gnugnoli M, Rinaldi C, Corallo F, Longhese MP. The DNA damage checkpoint: A tale from budding yeast. Front Genet 2022; 13:995163. [PMID: 36186482 PMCID: PMC9520983 DOI: 10.3389/fgene.2022.995163] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Accepted: 08/30/2022] [Indexed: 11/30/2022] Open
Abstract
Studies performed in the yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe have led the way in defining the DNA damage checkpoint and in identifying most of the proteins involved in this regulatory network, which turned out to have structural and functional equivalents in humans. Subsequent experiments revealed that the checkpoint is an elaborate signal transduction pathway that has the ability to sense and signal the presence of damaged DNA and transduce this information to influence a multifaceted cellular response that is essential for cancer avoidance. This review focuses on the work that was done in Saccharomyces cerevisiae to articulate the checkpoint concept, to identify its players and the mechanisms of activation and deactivation.
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8
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Fun30 and Rtt109 Mediate Epigenetic Regulation of the DNA Damage Response Pathway in C. albicans. J Fungi (Basel) 2022; 8:jof8060559. [PMID: 35736042 PMCID: PMC9225650 DOI: 10.3390/jof8060559] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Revised: 03/27/2022] [Accepted: 03/29/2022] [Indexed: 01/27/2023] Open
Abstract
Fun30, an ATP-dependent chromatin remodeler from S. cerevisiae, is known to mediate both regulation of gene expression as well as DNA damage response/repair. The Fun30 from C. albicans has not yet been elucidated. We show that C. albicans Fun30 is functionally homologous to both S. cerevisiae Fun30 and human SMARCAD1. Further, C. albicans Fun30 can mediate double-strand break end resection as well as regulate gene expression. This protein regulates transcription of RTT109, TEL1, MEC1, and SNF2-genes that encode for proteins involved in DNA damage response and repair pathways. The regulation mediated by C. albicans Fun30 is dependent on its ATPase activity. The expression of FUN30, in turn, is regulated by histone H3K56 acetylation catalyzed by Rtt109 and encoded by RTT109. The RTT109Hz/FUN30Hz mutant strain shows sensitivity to oxidative stress and resistance to MMS as compared to the wild-type strain. Quantitative PCR showed that the sensitivity to oxidative stress results from downregulation of MEC1, RAD9, MRC1, and RAD5 expression; ChIP experiments showed that Fun30 but not H3K56ac regulates the expression of these genes in response to oxidative stress. In contrast, upon treatment with MMS, the expression of RAD9 is upregulated, which is modulated by both Fun30 and H3K56 acetylation. Thus, Fun30 and H3K56 acetylation mediate the response to genotoxic agents in C. albicans by regulating the expression of DNA damage response and repair pathway genes.
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9
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Xie D, Zhao X, Ma L, Wang L, Li P, Cheng H, Li Z, Zeng P, Zhang J, Zeng F. Rba50 and Gpn2 recruit the second largest subunits for the assembly of RNA polymerase II and III. Int J Biol Macromol 2022; 204:565-575. [PMID: 35176321 DOI: 10.1016/j.ijbiomac.2022.02.052] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Revised: 02/09/2022] [Accepted: 02/10/2022] [Indexed: 11/18/2022]
Abstract
Although remarkable progress has been made toward understanding the structures of eukaryotic RNA polymerases, the pathways and factors that facilitate their assembly remain unresolved. Essential proteins Rba50 and Gpn2 are required for Rpb3 subcomplex assembly, but whether they participate in subsequent assembly steps is unknown. Herein, we performed comprehensive genetic screens to explore Rba50 function. We identified two unique extragenic rba50-3-suppressing mutations that map to genes encoding the Rba50-interacting protein Gpn2, and Rpb2, the second largest subunit of RNAPII. Both gpn2-R347S and rpb2-V1171G variants bypass Rpb1 cytoplasmic arrest and temperature-sensitive growth defects of the rba50-3 mutant. GPN2 and RPB2 were also identified as novel multicopy suppressors of the rba50-3 mutant. Rapid depletion of Rba50 affected Rpb3-Rpb2 association during RNAPII assembly. Importantly, we demonstrated that Gpn2 facilitates the association of Rba50 and Rpb2. Our results imply that Rba50-Gpn2 interaction is essential for Rpb2 recruitment during RNAPII assembly following Rpb3 subcomplex assembly. Furthermore, the Rba50-Gpn2 complex appears to play a similar role in the assembly of RNAPIII. We therefore propose a model in which Rba50 interacts with Gpn2 and thereby promotes loading of the second largest subunit of RNAP II and III onto the previously assembled subcomplex.
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Affiliation(s)
- Debao Xie
- State Key Laboratory of North China Crop Improvement and Regulation, Baoding, Hebei 071001, China; College of Life Sciences, Hebei Agricultural University, Baoding, Hebei 071001, China
| | - Xiangdong Zhao
- State Key Laboratory of North China Crop Improvement and Regulation, Baoding, Hebei 071001, China; College of Life Sciences, Hebei Agricultural University, Baoding, Hebei 071001, China
| | - Lujie Ma
- State Key Laboratory of North China Crop Improvement and Regulation, Baoding, Hebei 071001, China; College of Life Sciences, Hebei Agricultural University, Baoding, Hebei 071001, China
| | - Le Wang
- State Key Laboratory of North China Crop Improvement and Regulation, Baoding, Hebei 071001, China; College of Life Sciences, Hebei Agricultural University, Baoding, Hebei 071001, China
| | - Pan Li
- State Key Laboratory of North China Crop Improvement and Regulation, Baoding, Hebei 071001, China; College of Life Sciences, Hebei Agricultural University, Baoding, Hebei 071001, China
| | - Hongqian Cheng
- State Key Laboratory of North China Crop Improvement and Regulation, Baoding, Hebei 071001, China; College of Life Sciences, Hebei Agricultural University, Baoding, Hebei 071001, China
| | - Zhaoying Li
- State Key Laboratory of North China Crop Improvement and Regulation, Baoding, Hebei 071001, China; College of Life Sciences, Hebei Agricultural University, Baoding, Hebei 071001, China
| | - Pei Zeng
- State Key Laboratory of North China Crop Improvement and Regulation, Baoding, Hebei 071001, China; College of Life Sciences, Hebei Agricultural University, Baoding, Hebei 071001, China
| | - Jing Zhang
- State Key Laboratory of North China Crop Improvement and Regulation, Baoding, Hebei 071001, China; College of Life Sciences, Hebei Agricultural University, Baoding, Hebei 071001, China
| | - Fanli Zeng
- State Key Laboratory of North China Crop Improvement and Regulation, Baoding, Hebei 071001, China; College of Life Sciences, Hebei Agricultural University, Baoding, Hebei 071001, China.
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10
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Mfarej MG, Skibbens RV. Genetically induced redox stress occurs in a yeast model for Roberts syndrome. G3 (BETHESDA, MD.) 2022; 12:jkab426. [PMID: 34897432 PMCID: PMC9210317 DOI: 10.1093/g3journal/jkab426] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Accepted: 11/01/2021] [Indexed: 12/31/2022]
Abstract
Roberts syndrome (RBS) is a multispectrum developmental disorder characterized by severe limb, craniofacial, and organ abnormalities and often intellectual disabilities. The genetic basis of RBS is rooted in loss-of-function mutations in the essential N-acetyltransferase ESCO2 which is conserved from yeast (Eco1/Ctf7) to humans. ESCO2/Eco1 regulate many cellular processes that impact chromatin structure, chromosome transmission, gene expression, and repair of the genome. The etiology of RBS remains contentious with current models that include transcriptional dysregulation or mitotic failure. Here, we report evidence that supports an emerging model rooted in defective DNA damage responses. First, the results reveal that redox stress is elevated in both eco1 and cohesion factor Saccharomyces cerevisiae mutant cells. Second, we provide evidence that Eco1 and cohesion factors are required for the repair of oxidative DNA damage such that ECO1 and cohesin gene mutations result in reduced cell viability and hyperactivation of DNA damage checkpoints that occur in response to oxidative stress. Moreover, we show that mutation of ECO1 is solely sufficient to induce endogenous redox stress and sensitizes mutant cells to exogenous genotoxic challenges. Remarkably, antioxidant treatment desensitizes eco1 mutant cells to a range of DNA damaging agents, raising the possibility that modulating the cellular redox state may represent an important avenue of treatment for RBS and tumors that bear ESCO2 mutations.
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Affiliation(s)
- Michael G Mfarej
- Department of Biological Sciences, Lehigh University, Bethlehem, PA 18015, USA
| | - Robert V Skibbens
- Department of Biological Sciences, Lehigh University, Bethlehem, PA 18015, USA
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11
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Yao S, Feng Y, Zhang Y, Feng J. DNA damage checkpoint and repair: From the budding yeast Saccharomyces cerevisiae to the pathogenic fungus Candida albicans. Comput Struct Biotechnol J 2021; 19:6343-6354. [PMID: 34938410 PMCID: PMC8645783 DOI: 10.1016/j.csbj.2021.11.033] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 11/16/2021] [Accepted: 11/20/2021] [Indexed: 01/09/2023] Open
Abstract
Cells are constantly challenged by internal or external genotoxic assaults, which may induce a high frequency of DNA lesions, leading to genome instability. Accumulation of damaged DNA is severe or even lethal to cells and can result in abnormal proliferation that can cause cancer in multicellular organisms, aging or cell death. Eukaryotic cells have evolved a comprehensive defence system termed the DNA damage response (DDR) to monitor and remove lesions in their DNA. The DDR has been extensively studied in the budding yeast Saccharomyces cerevisiae. Emerging evidence indicates that DDR genes in the pathogenic fungus Candida albicans show functional consistency with their orthologs in S. cerevisiae, but may act through distinct mechanisms. In particular, the DDR in C. albicans appears critical for resisting DNA damage stress induced by reactive oxygen species (ROS) produced from immune cells, and this plays a vital role in pathogenicity. Therefore, DDR genes could be considered as potential targets for clinical therapies. This review summarizes the identified DNA damage checkpoint and repair genes in C. albicans based on their orthologs in S. cerevisiae, and discusses their contribution to pathogenicity in C. albicans.
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Affiliation(s)
- Shuangyan Yao
- Department of Pathogen Biology, School of Medicine, Nantong University, Nantong 226001, Jiangsu, China
- Nantong Health College of Jiangsu Province, Nantong 226016, Jiangsu, China
| | - Yuting Feng
- Department of Pathogen Biology, School of Medicine, Nantong University, Nantong 226001, Jiangsu, China
| | - Yan Zhang
- Department of Pathogen Biology, School of Medicine, Nantong University, Nantong 226001, Jiangsu, China
| | - Jinrong Feng
- Department of Pathogen Biology, School of Medicine, Nantong University, Nantong 226001, Jiangsu, China
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12
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Endosomal trafficking and DNA damage checkpoint kinases dictate survival to replication stress by regulating amino acid uptake and protein synthesis. Dev Cell 2021; 56:2607-2622.e6. [PMID: 34534458 DOI: 10.1016/j.devcel.2021.08.019] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Revised: 06/11/2021] [Accepted: 08/20/2021] [Indexed: 12/22/2022]
Abstract
Atg6Beclin 1 mediates autophagy and endosomal trafficking. We investigated how Atg6 influences replication stress. Combining genetic, genomic, metabolomic, and proteomic approaches, we found that the Vps34-Vps15-Atg6Beclin 1-Vps38UVRAG-phosphatydilinositol-3 phosphate (PtdIns(3)P) axis sensitizes cells to replication stress by favoring the degradation of plasma membrane amino acid (AA) transporters via endosomal trafficking and ESCRT proteins, while the PtdIns(3)P phosphatases Ymr1 and Inp53 promote survival to replication stress by reversing this process. An impaired AA uptake triggers activation of Gcn2, which attenuates protein synthesis by phosphorylating eIF2α. Mec1Atr-Rad53Chk1/Chk2 activation during replication stress further hinders translation efficiency by counteracting eIF2α dephosphorylation through Glc7PP1. AA shortage-induced hyperphosphorylation of eIF2α inhibits the synthesis of 65 stress response proteins, thus resulting in cell sensitization to replication stress, while TORC1 promotes cell survival. Our findings reveal an integrated network mediated by endosomal trafficking, translational control pathways, and checkpoint kinases linking AA availability to the response to replication stress.
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Katheeja MN, Das SP, Laha S. The budding yeast protein Chl1p is required for delaying progression through G1/S phase after DNA damage. Cell Div 2021; 16:4. [PMID: 34493312 PMCID: PMC8424871 DOI: 10.1186/s13008-021-00072-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Accepted: 08/20/2021] [Indexed: 11/17/2022] Open
Abstract
Background The budding yeast protein Chl1p is a nuclear protein required for sister-chromatid cohesion, transcriptional silencing, rDNA recombination, ageing and plays an instrumental role in chromatin remodeling. This helicase is known to preserve genome integrity and spindle length in S-phase. Here we show additional roles of Chl1p at G1/S phase of the cell cycle following DNA damage. Results G1 arrested cells when exposed to DNA damage are more sensitive and show bud emergence with faster kinetics in chl1 mutants compared to wild-type cells. Also, more damage to DNA is observed in chl1 cells. The viability falls synergistically in rad24chl1 cells. The regulation of Chl1p on budding kinetics in G1 phase falls in line with Rad9p/Chk1p and shows a synergistic effect with Rad24p/Rad53p. rad9chl1 and chk1chl1 shows similar bud emergence as the single mutants chl1, rad9 and chk1. Whereas rad24chl1 and rad53chl1 shows faster bud emergence compared to the single mutants rad24, rad53 and chl1. In presence of MMS induced damage, synergistic with Rad24p indicates Chl1p’s role as a checkpoint at G1/S acting parallel to damage checkpoint pathway. The faster movement of DNA content through G1/S phase and difference in phosphorylation profile of Rad53p in wild type and chl1 cells confirms the checkpoint defect in chl1 mutant cells. Further, we have also confirmed that the checkpoint defect functions in parallel to the damage checkpoint pathway of Rad24p. Conclusion Chl1p shows Rad53p independent bud emergence and Rad53p dependent checkpoint activity in presence of damage. This confirms its requirement in two different pathways to maintain the G1/S arrest when cells are exposed to damaging agents. The bud emergence kinetics and DNA segregation were similar to wild type when given the same damage in nocodazole treated chl1 cells which establishes the absence of any role of Chl1p at the G2/M phase. The novelty of this paper lies in revealing the versatile role of Chl1p in checkpoints as well as repair towards regulating G1/S transition. Chl1p thus regulates the G1/S phase by affecting the G1 replication checkpoint pathway and shows an additive effect with Rad24p for Rad53p activation when damaging agents perturb the DNA. Apart from checkpoint activation, it also regulates the budding kinetics as a repair gene. Supplementary Information The online version contains supplementary material available at 10.1186/s13008-021-00072-x.
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Affiliation(s)
- Muhseena N Katheeja
- Cell Biology and Molecular Genetics Division, Yenepoya Research Centre, Yenepoya Medical College, Yenepoya (Deemed To Be University), University Road, 3rd floor, Academic block, Deralakatte, Mangalore, 575018, India
| | - Shankar Prasad Das
- Cell Biology and Molecular Genetics Division, Yenepoya Research Centre, Yenepoya Medical College, Yenepoya (Deemed To Be University), University Road, 3rd floor, Academic block, Deralakatte, Mangalore, 575018, India. .,Department of Biochemistry, Bose Institute, P1/12 CIT Scheme VII M, 700 054, Kolkata, India.
| | - Suparna Laha
- Cell Biology and Molecular Genetics Division, Yenepoya Research Centre, Yenepoya Medical College, Yenepoya (Deemed To Be University), University Road, 3rd floor, Academic block, Deralakatte, Mangalore, 575018, India. .,Department of Biochemistry, Bose Institute, P1/12 CIT Scheme VII M, 700 054, Kolkata, India.
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14
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Yahya G, Hashem Mohamed N, Pijuan J, Seleem NM, Mosbah R, Hess S, Abdelmoaty AA, Almeer R, Abdel‐Daim MM, Shulaywih Alshaman H, Juraiby I, Metwally K, Storchova Z. Profiling the physiological pitfalls of anti-hepatitis C direct-acting agents in budding yeast. Microb Biotechnol 2021; 14:2199-2213. [PMID: 34378349 PMCID: PMC8449668 DOI: 10.1111/1751-7915.13904] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 07/16/2021] [Accepted: 07/17/2021] [Indexed: 02/05/2023] Open
Abstract
Sofosbuvir and Daclatasvir are among the direct-acting antiviral (DAA) medications prescribed for the treatment of chronic hepatitis C (CHC) virus infection as combination therapy with other antiviral medications. DAA-based therapy achieves high cure rates, reaching up to 97% depending on the genotype of the causative hepatitis C virus (HCV). While DAAs have been approved as an efficient and well-tolerated therapy for CHC, emerging concerns about adverse cardiac side effects, higher risk of recurrence and occurrence of hepatocellular carcinoma (HCC) and doubts of genotoxicity have been reported. In our study, we investigated in detail physiological off-targets of DAAs and dissected the effects of these drugs on cellular organelles using budding yeast, a unicellular eukaryotic organism. DAAs were found to disturb the architecture of the endoplasmic reticulum (ER) and the mitochondria, while showing no apparent genotoxicity or DNA damaging effect. Our study provides evidence that DAAs are not associated with genotoxicity and highlights the necessity for adjunctive antioxidant therapy to mitigate the adverse effects of DAAs on ER and mitochondria.
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Affiliation(s)
- Galal Yahya
- Department of Microbiology and ImmunologyFaculty of PharmacyZagazig UniversityAl Sharqia44519Egypt
- Department of Molecular GeneticsFaculty of BiologyTechnical University of KaiserslauternPaul‐Ehrlich Str. 24Kaiserslautern67663Germany
| | | | - Jordi Pijuan
- Laboratory of Neurogenetics and Molecular Medicine ‐ IPERInstitut de Recerca Sant Joan de DéuBarcelona08950Spain
| | - Noura M. Seleem
- Department of Microbiology and ImmunologyFaculty of PharmacyZagazig UniversityAl Sharqia44519Egypt
| | - Rasha Mosbah
- Infection Control UnitHospitals of Zagazig UniversityAl SharqiaEgypt
| | - Steffen Hess
- Department of Cell BiologyFaculty of BiologyTechnical University of KaiserslauternKaiserslauternGermany
| | - Ahmed A. Abdelmoaty
- Department of Tropical MedicineFaculty of MedicineZagazig UniversityZagazig44519Egypt
| | - Rafa Almeer
- Department of ZoologyCollege of ScienceKing Saud UniversityP.O. Box 2455Riyadh11451Saudi Arabia
| | - Mohamed M. Abdel‐Daim
- Department of ZoologyCollege of ScienceKing Saud UniversityP.O. Box 2455Riyadh11451Saudi Arabia
- Pharmacology DepartmentCollege of Veterinary MedicineSuez Canal UniversityIsmailiaEgypt
| | | | - Ibrahim Juraiby
- General Directorate of Health AffairsMinistry of HealthJazan82723Saudi Arabia
| | - Kamel Metwally
- Department of Pharmaceutical ChemistryFaculty of PharmacyTabuk UniversityTabuk47713Saudi Arabia
- Department of Medicinal ChemistryFaculty of PharmacyZagazig UniversityZagazig44519Egypt
| | - Zuzana Storchova
- Department of Molecular GeneticsFaculty of BiologyTechnical University of KaiserslauternPaul‐Ehrlich Str. 24Kaiserslautern67663Germany
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15
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Learning Yeast Genetics from Miro Radman. Cells 2021; 10:cells10040945. [PMID: 33923882 PMCID: PMC8072546 DOI: 10.3390/cells10040945] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 04/13/2021] [Accepted: 04/13/2021] [Indexed: 11/17/2022] Open
Abstract
Miroslav Radman's far-sighted ideas have penetrated many aspects of our study of the repair of broken eukaryotic chromosomes. For over 35 years my lab has studied different aspects of the repair of chromosomal breaks in the budding yeast, Saccharomyces cerevisiae. From the start, we have made what we thought were novel observations that turned out to have been predicted by Miro's extraordinary work in the bacterium Escherichia coli and then later in the radiation-resistant Dienococcus radiodurans. In some cases, we have been able to extend some of his ideas a bit further.
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16
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Usui T, Shinohara A. Rad9, a 53BP1 Ortholog of Budding Yeast, Is Insensitive to Spo11-Induced Double-Strand Breaks During Meiosis. Front Cell Dev Biol 2021; 9:635383. [PMID: 33842461 PMCID: PMC8027355 DOI: 10.3389/fcell.2021.635383] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Accepted: 02/25/2021] [Indexed: 12/04/2022] Open
Abstract
Exogenous double-strand breaks (DSBs) induce a DNA damage response during mitosis as well as meiosis. The DNA damage response is mediated by a cascade involving Mec1/Tel1 (ATR/ATM) and Rad53 (Chk2) kinases. Meiotic cells are programmed to form DSBs for the initiation of meiotic recombination. In budding yeast, Spo11-mediated meiotic DSBs activate Mec1/Tel1, but not Rad53; however, the mechanism underlying the insensitivity of Rad53 to meiotic DSBs remains largely unknown. In this study, we found that meiotic cells activate Rad53 in response to exogenous DSBs and that this activation is dependent on an epigenetic marker, Dot1-dependent histone H3K79 methylation, which becomes a scaffold of an Rad53 mediator, Rad9, an ortholog of 53BP1. In contrast, Rad9 is insensitive to meiotic programmed DSBs. This insensitiveness of Rad9 derives from its inability to bind to the DSBs. Indeed, artificial tethering of Rad9 to the meiotic DSBs activated Rad53. The artificial activation of Rad53 kinase in meiosis decreases the repair of meiotic DSBs. These results suggest that the suppression of Rad53 activation is a key event in initiating a meiotic program that repairs programmed DSBs.
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Affiliation(s)
- Takehiko Usui
- Institute for Protein Research, Osaka University, Suita, Japan
| | - Akira Shinohara
- Institute for Protein Research, Osaka University, Suita, Japan
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17
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Abstract
In order to preserve genome integrity, all cells must mount appropriate responses to DNA damage, including slowing down or arresting the cell cycle to give the cells time to repair the damage and changing gene expression, for example to induce genes involved in DNA repair. The Rad53 protein kinase is a conserved central mediator of these responses in eukaryotic cells, and its extensive phosphorylation upon DNA damage is necessary for its activation and subsequent activity. DNA damage checkpoints are key guardians of genome integrity. Eukaryotic cells respond to DNA damage by triggering extensive phosphorylation of Rad53/CHK2 effector kinase, whereupon activated Rad53/CHK2 mediates further aspects of checkpoint activation, including cell cycle arrest and transcriptional changes. Budding yeast Candida glabrata, closely related to model eukaryote Saccharomyces cerevisiae, is an opportunistic pathogen characterized by high genetic diversity and rapid emergence of drug-resistant mutants. However, the mechanisms underlying this genetic variability are unclear. We used Western blotting and mass spectrometry to show that, unlike S. cerevisiae, C. glabrata cells exposed to DNA damage did not induce C. glabrata Rad53 (CgRad53) phosphorylation. Furthermore, flow cytometry analysis showed that, unlike S. cerevisiae, C. glabrata cells did not accumulate in S phase upon DNA damage. Consistent with these observations, time-lapse microscopy showed C. glabrata cells continuing to divide in the presence of DNA damage, resulting in mitotic errors and cell death. Finally, transcriptome sequencing (RNAseq) analysis revealed transcriptional rewiring of the DNA damage response in C. glabrata and identified several key protectors of genome stability upregulated by DNA damage in S. cerevisiae but downregulated in C. glabrata, including proliferating cell nuclear antigen (PCNA). Together, our results reveal a noncanonical fungal DNA damage response in C. glabrata, which may contribute to rapidly generating genetic change and drug resistance.
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18
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Tannous EA, Yates LA, Zhang X, Burgers PM. Mechanism of auto-inhibition and activation of Mec1 ATR checkpoint kinase. Nat Struct Mol Biol 2020; 28:50-61. [PMID: 33169019 PMCID: PMC7855233 DOI: 10.1038/s41594-020-00522-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Accepted: 09/24/2020] [Indexed: 01/01/2023]
Abstract
In response to DNA damage or replication fork stalling, the basal activity of Mec1ATR is stimulated in a cell-cycle-dependent manner, leading to cell-cycle arrest and the promotion of DNA repair. Mec1ATR dysfunction leads to cell death in yeast and causes chromosome instability and embryonic lethality in mammals. Thus, ATR is a major target for cancer therapies in homologous recombination-deficient cancers. Here we identify a single mutation in Mec1, conserved in ATR, that results in constitutive activity. Using cryo-electron microscopy, we determine the structures of this constitutively active form (Mec1(F2244L)-Ddc2) at 2.8 Å and the wild type at 3.8 Å, both in complex with Mg2+-AMP-PNP. These structures yield a near-complete atomic model for Mec1-Ddc2 and uncover the molecular basis for low basal activity and the conformational changes required for activation. Combined with biochemical and genetic data, we discover key regulatory regions and propose a Mec1 activation mechanism.
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Affiliation(s)
- Elias A Tannous
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, Saint Louis, MO, USA
| | - Luke A Yates
- Section of Structural Biology, Department of Infectious Disease, Imperial College London, South Kensington, London, UK
| | - Xiaodong Zhang
- Section of Structural Biology, Department of Infectious Disease, Imperial College London, South Kensington, London, UK.
| | - Peter M Burgers
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, Saint Louis, MO, USA.
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19
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Gupta P, Meena RC, Kumar N. Functional characterization of Candida glabrata ORF, CAGL0M02233g for its role in stress tolerance and virulence. Microb Pathog 2020; 149:104469. [PMID: 32890635 DOI: 10.1016/j.micpath.2020.104469] [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: 05/06/2020] [Revised: 08/24/2020] [Accepted: 08/25/2020] [Indexed: 01/06/2023]
Abstract
Present investigation is aimed to analyze the role of an uncharacterized ORF of Candida glabrata (CBS138), CAGL0M02233g (an ortholog of RAD53, a key DNA checkpoint effector in Saccharomyces cerevisiae) in tolerance of various stresses and in biofilm formation. The CAGL0M02233g was cloned in p416TEF shuttle vector for constitutive expression under TEF1 promoter in BG14 strain (ura3 auxotrophic C. glabrata), and upregulated expression of the cloned ORF was confirmed by immunoblotting. The constitutive expression of CAGL0M02233g rendered cells resistant to the DNA damage stressor (MMS), replication stressor (HU) and hypoxia mimetic (CoCl2) in plate spot and growth curve assays. Hypoxia (a low oxygen condition) is an imperative host factor that influences Candida pathogenesis. Biofilm formation by the BG14 cells transformed with p416TEF-CAGL0M02233g (REX cell) was reduced to approximately 50% under hypoxia. It is notable that biofilm formation by the REX cells was significantly lower than that of BG14 cells transformed with p416TEF vector (VC cell) under hypoxia. The biofilm of the REX cells has shown higher susceptibility to fluconazole than that of VC cells under hypoxia and REX cells at normoxia. This is the first report on the function of CAGL0M02233g in tolerance of various stressors and in modulation of the biofilm under hypoxia.
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Affiliation(s)
- Payal Gupta
- Department of Biotechnology, Graphic Era (Deemed to be University), 566/6, Bell Road, Clement Town, Dehradun, PIN-248002, India
| | - R C Meena
- Molecular Biology Division, Defence Institute of Physiology and Allied Sciences, Lucknow Road, Timarpur, Delhi, 110054, India
| | - Navin Kumar
- Department of Biotechnology, Graphic Era (Deemed to be University), 566/6, Bell Road, Clement Town, Dehradun, PIN-248002, India.
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20
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Abstract
Cells confront DNA damage in every cell cycle. Among the most deleterious types of DNA damage are DNA double-strand breaks (DSBs), which can cause cell lethality if unrepaired or cancers if improperly repaired. In response to DNA DSBs, cells activate a complex DNA damage checkpoint (DDC) response that arrests the cell cycle, reprograms gene expression, and mobilizes DNA repair factors to prevent the inheritance of unrepaired and broken chromosomes. Here we examine the DDC, induced by DNA DSBs, in the budding yeast model system and in mammals.
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Affiliation(s)
- David P Waterman
- Department of Biology and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, Massachusetts 02454, USA;
| | - James E Haber
- Department of Biology and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, Massachusetts 02454, USA;
| | - Marcus B Smolka
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, New York 14853, USA;
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21
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Saccharomyces cerevisiae Mus81-Mms4 prevents accelerated senescence in telomerase-deficient cells. PLoS Genet 2020; 16:e1008816. [PMID: 32469862 PMCID: PMC7286520 DOI: 10.1371/journal.pgen.1008816] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Revised: 06/10/2020] [Accepted: 04/30/2020] [Indexed: 01/31/2023] Open
Abstract
Alternative lengthening of telomeres (ALT) in human cells is a conserved process that is often activated in telomerase-deficient human cancers. This process exploits components of the recombination machinery to extend telomere ends, thus allowing for increased proliferative potential. Human MUS81 (Mus81 in Saccharomyces cerevisiae) is the catalytic subunit of structure-selective endonucleases involved in recombination and has been implicated in the ALT mechanism. However, it is unclear whether MUS81 activity at the telomere is specific to ALT cells or if it is required for more general aspects of telomere stability. In this study, we use S. cerevisiae to evaluate the contribution of the conserved Mus81-Mms4 endonuclease in telomerase-deficient yeast cells that maintain their telomeres by mechanisms akin to human ALT. Similar to human cells, we find that yeast Mus81 readily localizes to telomeres and its activity is important for viability after initial loss of telomerase. Interestingly, our analysis reveals that yeast Mus81 is not required for the survival of cells undergoing recombination-mediated telomere lengthening, i.e. for ALT itself. Rather we infer from genetic analysis that Mus81-Mms4 facilitates telomere replication during times of telomere instability. Furthermore, combining mus81 mutants with mutants of a yeast telomere replication factor, Rrm3, reveals that the two proteins function in parallel to promote normal growth during times of telomere stress. Combined with previous reports, our data can be interpreted in a consistent model in which both yeast and human MUS81-dependent nucleases participate in the recovery of stalled replication forks within telomeric DNA. Furthermore, this process becomes crucial under conditions of additional replication stress, such as telomere replication in telomerase-deficient cells. Cancer cell divisions require active chromosome lengthening through extension of their highly repetitive ends, called telomeres. This process is accomplished through two main mechanisms: the activity of an RNA-protein complex, telomerase, or through a telomerase-independent process termed alternative lengthening of telomeres (ALT). Human MUS81, the catalytic subunit of a set of structure-selective endonucleases, was found to be essential in human cells undergoing ALT and proposed to be directly involved in telomere lengthening. Using telomerase-deficient Saccharomyces cerevisiae cells as a model for ALT, we tested the hypothesis that Mus81-Mms4, the budding yeast homolog of human MUS81-dependent nucleases, is essential for telomere lengthening as proposed for human cells. Using genetic and molecular assays we confirm that Mus81-Mms4 is involved in telomere metabolism in yeast. However, to our surprise, we find that Mus81-Mms4 is not directly involved in recombination-based mechanisms of telomere lengthening. Rather it appears that Mus81-Mms4 is involved in resolving replication stress at telomeres, which is augmented in cells undergoing telomere instability. This model is consistent with observations in mammalian cells and suggest that cells undergoing telomere shortening experience replication stress at telomeres.
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22
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Morafraile EC, Bugallo A, Carreira R, Fernández M, Martín-Castellanos C, Blanco MG, Segurado M. Exo1 phosphorylation inhibits exonuclease activity and prevents fork collapse in rad53 mutants independently of the 14-3-3 proteins. Nucleic Acids Res 2020; 48:3053-3070. [PMID: 32020204 PMCID: PMC7102976 DOI: 10.1093/nar/gkaa054] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Revised: 01/15/2020] [Accepted: 01/20/2020] [Indexed: 01/04/2023] Open
Abstract
The S phase checkpoint is crucial to maintain genome stability under conditions that threaten DNA replication. One of its critical functions is to prevent Exo1-dependent fork degradation, and Exo1 is phosphorylated in response to different genotoxic agents. Exo1 seemed to be regulated by several post-translational modifications in the presence of replicative stress, but the specific contribution of checkpoint-dependent phosphorylation to Exo1 control and fork stability is not clear. We show here that Exo1 phosphorylation is Dun1-independent and Rad53-dependent in response to DNA damage or dNTP depletion, and in both situations Exo1 is similarly phosphorylated at multiple sites. To investigate the correlation between Exo1 phosphorylation and fork stability, we have generated phospho-mimic exo1 alleles that rescue fork collapse in rad53 mutants as efficiently as exo1-nuclease dead mutants or the absence of Exo1, arguing that Rad53-dependent phosphorylation is the mayor requirement to preserve fork stability. We have also shown that this rescue is Bmh1–2 independent, arguing that the 14-3-3 proteins are dispensable for fork stabilization, at least when Exo1 is downregulated. Importantly, our results indicated that phosphorylation specifically inhibits the 5' to 3'exo-nuclease activity, suggesting that this activity of Exo1 and not the flap-endonuclease, is the enzymatic activity responsible of the collapse of stalled replication forks in checkpoint mutants.
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Affiliation(s)
- Esther C Morafraile
- Instituto de Biología Funcional y Genómica (CSIC/USAL), Campus Miguel de Unamuno, Salamanca 37007, Spain
| | - Alberto Bugallo
- Instituto de Biología Funcional y Genómica (CSIC/USAL), Campus Miguel de Unamuno, Salamanca 37007, Spain
| | - Raquel Carreira
- Departamento de Bioquímica y Biología Molecular, Centro de Investigación en Medicina Molecular y Enfermedades Crónicas (CIMUS) - Instituto de Investigación Sanitaria (IDIS), Universidad de Santiago de Compostela, 15782 Santiago de Compostela, Spain
| | - María Fernández
- Instituto de Biología Funcional y Genómica (CSIC/USAL), Campus Miguel de Unamuno, Salamanca 37007, Spain
| | | | - Miguel G Blanco
- Departamento de Bioquímica y Biología Molecular, Centro de Investigación en Medicina Molecular y Enfermedades Crónicas (CIMUS) - Instituto de Investigación Sanitaria (IDIS), Universidad de Santiago de Compostela, 15782 Santiago de Compostela, Spain
| | - Mónica Segurado
- Instituto de Biología Funcional y Genómica (CSIC/USAL), Campus Miguel de Unamuno, Salamanca 37007, Spain.,Departamento de Microbiología y Genética, Campus Miguel de Unamuno, Universidad de Salamanca, Salamanca 37007, Spain
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23
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Cussiol JRR, Soares BL, Oliveira FMBD. From yeast to humans: Understanding the biology of DNA Damage Response (DDR) kinases. Genet Mol Biol 2019; 43:e20190071. [PMID: 31930279 PMCID: PMC7198005 DOI: 10.1590/1678-4685-gmb-2019-0071] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Accepted: 07/19/2019] [Indexed: 12/20/2022] Open
Abstract
The DNA Damage Response (DDR) is a complex network of biological processes that protect cells from accumulating aberrant DNA structures, thereby maintaining genomic stability and, as a consequence, preventing the development of cancer and other diseases. The DDR pathway is coordinated by a signaling cascade mediated by the PI3K-like kinases (PIKK) ATM and ATR and by their downstream kinases CHK2 and CHK1, respectively. Together, these kinases regulate several aspects of the cellular program in response to genomic stress. Much of our understanding of these kinases came from studies performed in the 1990s using yeast as a model organism. The purpose of this review is to present a historical perspective on the discovery of the DDR kinases in yeast and the importance of this model for the identification and functional understanding of their mammalian orthologues.
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Affiliation(s)
| | - Bárbara Luísa Soares
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
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24
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Lanz MC, Dibitetto D, Smolka MB. DNA damage kinase signaling: checkpoint and repair at 30 years. EMBO J 2019; 38:e101801. [PMID: 31393028 PMCID: PMC6745504 DOI: 10.15252/embj.2019101801] [Citation(s) in RCA: 159] [Impact Index Per Article: 31.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Revised: 07/03/2019] [Accepted: 07/24/2019] [Indexed: 12/27/2022] Open
Abstract
From bacteria to mammalian cells, damaged DNA is sensed and targeted by DNA repair pathways. In eukaryotes, kinases play a central role in coordinating the DNA damage response. DNA damage signaling kinases were identified over two decades ago and linked to the cell cycle checkpoint concept proposed by Weinert and Hartwell in 1988. Connections between the DNA damage signaling kinases and DNA repair were scant at first, and the initial perception was that the importance of these kinases for genome integrity was largely an indirect effect of their roles in checkpoints, DNA replication, and transcription. As more substrates of DNA damage signaling kinases were identified, it became clear that they directly regulate a wide range of DNA repair factors. Here, we review our current understanding of DNA damage signaling kinases, delineating the key substrates in budding yeast and humans. We trace the progress of the field in the last 30 years and discuss our current understanding of the major substrate regulatory mechanisms involved in checkpoint responses and DNA repair.
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Affiliation(s)
- Michael Charles Lanz
- Department of Molecular Biology and GeneticsWeill Institute for Cell and Molecular BiologyCornell UniversityIthacaNYUSA
| | - Diego Dibitetto
- Department of Molecular Biology and GeneticsWeill Institute for Cell and Molecular BiologyCornell UniversityIthacaNYUSA
| | - Marcus Bustamante Smolka
- Department of Molecular Biology and GeneticsWeill Institute for Cell and Molecular BiologyCornell UniversityIthacaNYUSA
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25
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Julius J, Peng J, McCulley A, Caridi C, Arnak R, See C, Nugent CI, Feng W, Bachant J. Inhibition of spindle extension through the yeast S phase checkpoint is coupled to replication fork stability and the integrity of centromeric DNA. Mol Biol Cell 2019; 30:2771-2789. [PMID: 31509480 PMCID: PMC6789157 DOI: 10.1091/mbc.e19-03-0156] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Budding yeast treated with hydroxyurea (HU) activate the S phase checkpoint kinase Rad53, which prevents DNA replication forks from undergoing aberrant structural transitions and nuclease processing. Rad53 is also required to prevent premature extension of the mitotic spindle that assembles during a HU-extended S phase. Here we present evidence that checkpoint restraint of spindle extension is directly coupled to Rad53 control of replication fork stability. In budding yeast, centromeres are flanked by replication origins that fire in early S phase. Mutations affecting the Zn2+-finger of Dbf4, an origin activator, preferentially reduce centromere-proximal origin firing in HU, corresponding with suppression of rad53 spindle extension. Inactivating Exo1 nuclease or displacing centromeres from origins provides a similar suppression. Conversely, short-circuiting Rad53 targeting of Dbf4, Sld3, and Dun1, substrates contributing to fork stability, induces spindle extension. These results reveal spindle extension in HU-treated rad53 mutants is a consequence of replication fork catastrophes at centromeres. When such catastrophes occur, centromeres become susceptible to nucleases, disrupting kinetochore function and spindle force balancing mechanisms. At the same time, our data indicate centromere duplication is not required to stabilize S phase spindle structure, leading us to propose a model for how monopolar kinetochore-spindle attachments may contribute to spindle force balance in HU.
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Affiliation(s)
- Jeff Julius
- Department of Molecular Cell Systems Biology, University of California, Riverside, Riverside, CA 92521
| | - Jie Peng
- Department of Biochemistry and Molecular Biology, State University of New York Upstate Medical University, Syracuse, NY 13210
| | - Andrew McCulley
- Department of Biochemistry and Molecular Biology, State University of New York Upstate Medical University, Syracuse, NY 13210
| | - Chris Caridi
- Department of Molecular Cell Systems Biology, University of California, Riverside, Riverside, CA 92521
| | - Remigiusz Arnak
- Department of Biochemistry and Molecular Biology, State University of New York Upstate Medical University, Syracuse, NY 13210
| | - Colby See
- Department of Molecular Cell Systems Biology, University of California, Riverside, Riverside, CA 92521
| | - Constance I Nugent
- Department of Molecular Cell Systems Biology, University of California, Riverside, Riverside, CA 92521
| | - Wenyi Feng
- Department of Biochemistry and Molecular Biology, State University of New York Upstate Medical University, Syracuse, NY 13210
| | - Jeff Bachant
- Department of Molecular Cell Systems Biology, University of California, Riverside, Riverside, CA 92521
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26
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Ayra-Plasencia J, Machín F. DNA double-strand breaks in telophase lead to coalescence between segregated sister chromatid loci. Nat Commun 2019; 10:2862. [PMID: 31253793 PMCID: PMC6598993 DOI: 10.1038/s41467-019-10742-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Accepted: 05/30/2019] [Indexed: 12/24/2022] Open
Abstract
DNA double strand breaks (DSBs) pose a high risk for genome integrity. Cells repair DSBs through homologous recombination (HR) when a sister chromatid is available. HR is upregulated by the cycling dependent kinase (CDK) despite the paradox of telophase, where CDK is high but a sister chromatid is not nearby. Here we study in the budding yeast the response to DSBs in telophase, and find they activate the DNA damage checkpoint (DDC), leading to a telophase-to-G1 delay. Outstandingly, we observe a partial reversion of sister chromatid segregation, which includes approximation of segregated material, de novo formation of anaphase bridges, and coalescence between sister loci. We finally show that DSBs promote a massive change in the dynamics of telophase microtubules (MTs), together with dephosphorylation and relocalization of kinesin-5 Cin8. We propose that chromosome segregation is not irreversible and that DSB repair using the sister chromatid is possible in telophase.
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Affiliation(s)
- Jessel Ayra-Plasencia
- Unidad de Investigación, Hospital Universitario Nuestra Señora de Candelaria, Santa Cruz de Tenerife, Spain
- Escuela de Doctorado y Estudios de Posgrado, Universidad de La Laguna, Santa Cruz de Tenerife, Spain
| | - Félix Machín
- Unidad de Investigación, Hospital Universitario Nuestra Señora de Candelaria, Santa Cruz de Tenerife, Spain.
- Instituto de Tecnologías Biomédicas, Universidad de La Laguna, Santa Cruz de Tenerife, Spain.
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27
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Barnum KJ, Nguyen YT, O'Connell MJ. XPG-related nucleases are hierarchically recruited for double-stranded rDNA break resection. J Biol Chem 2019; 294:7632-7643. [PMID: 30885940 DOI: 10.1074/jbc.ra118.005415] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Revised: 03/11/2019] [Indexed: 12/11/2022] Open
Abstract
dsDNA breaks (DSBs) are resected in a 5'→3' direction, generating single-stranded DNA (ssDNA). This promotes DNA repair by homologous recombination and also assembly of signaling complexes that activate the DNA damage checkpoint effector kinase Chk1. In fission yeast (Schizosaccharomyces pombe), genetic screens have previously uncovered a family of three xeroderma pigmentosum G (XPG)-related nucleases (XRNs), known as Ast1, Exo1, and Rad2. Collectively, these XRNs are recruited to a euchromatic DSB and are required for ssDNA production and end resection across the genome. Here, we studied why there are three related but distinct XRN enzymes that are all conserved across a range of species, including humans, whereas all other DSB response proteins are present as single species. Using S. pombe as a model, ChIP and DSB resection analysis assays, and highly efficient I-PpoI-induced DSBs in the 28S rDNA gene, we observed a hierarchy of recruitment for each XRN, with a progressive compensatory recruitment of the other XRNs as the responding enzymes are deleted. Importantly, we found that this hierarchy reflects the requirement for different XRNs to effect efficient DSB resection in the rDNA, demonstrating that the presence of three XRN enzymes is not a simple division of labor. Furthermore, we uncovered a specificity of XRN function with regard to the direction of transcription. We conclude that the DSB-resection machinery is complex, is nonuniform across the genome, and has built-in fail-safe mechanisms, features that are in keeping with the highly pathological nature of DSB lesions.
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Affiliation(s)
- Kevin J Barnum
- From the Department of Oncological Sciences and.,Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, New York, New York 10029
| | - Y Tram Nguyen
- From the Department of Oncological Sciences and.,Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, New York, New York 10029
| | - Matthew J O'Connell
- From the Department of Oncological Sciences and .,Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, New York, New York 10029
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28
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Rpd3L Contributes to the DNA Damage Sensitivity of Saccharomyces cerevisiae Checkpoint Mutants. Genetics 2018; 211:503-513. [PMID: 30559326 PMCID: PMC6366903 DOI: 10.1534/genetics.118.301817] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Accepted: 11/26/2018] [Indexed: 12/26/2022] Open
Abstract
DNA replication forks that are stalled by DNA damage activate an S-phase checkpoint that prevents irreversible fork arrest and cell death. The increased cell death caused by DNA damage in budding yeast cells lacking the Rad53 checkpoint protein kinase is partially suppressed by deletion of the EXO1 gene. Using a whole-genome sequencing approach, we identified two additional genes, RXT2 and RPH1, whose mutation can also partially suppress this DNA damage sensitivity. We provide evidence that RXT2 and RPH1 act in a common pathway, which is distinct from the EXO1 pathway. Analysis of additional mutants indicates that suppression works through the loss of the Rpd3L histone deacetylase complex. Our results suggest that the loss or absence of histone acetylation, perhaps at stalled forks, may contribute to cell death in the absence of a functional checkpoint.
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29
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Pathways and Mechanisms that Prevent Genome Instability in Saccharomyces cerevisiae. Genetics 2017; 206:1187-1225. [PMID: 28684602 PMCID: PMC5500125 DOI: 10.1534/genetics.112.145805] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Accepted: 04/26/2017] [Indexed: 12/13/2022] Open
Abstract
Genome rearrangements result in mutations that underlie many human diseases, and ongoing genome instability likely contributes to the development of many cancers. The tools for studying genome instability in mammalian cells are limited, whereas model organisms such as Saccharomyces cerevisiae are more amenable to these studies. Here, we discuss the many genetic assays developed to measure the rate of occurrence of Gross Chromosomal Rearrangements (called GCRs) in S. cerevisiae. These genetic assays have been used to identify many types of GCRs, including translocations, interstitial deletions, and broken chromosomes healed by de novo telomere addition, and have identified genes that act in the suppression and formation of GCRs. Insights from these studies have contributed to the understanding of pathways and mechanisms that suppress genome instability and how these pathways cooperate with each other. Integrated models for the formation and suppression of GCRs are discussed.
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30
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Saiz-Baggetto S, Méndez E, Quilis I, Igual JC, Bañó MC. Chimeric proteins tagged with specific 3xHA cassettes may present instability and functional problems. PLoS One 2017; 12:e0183067. [PMID: 28800621 PMCID: PMC5553802 DOI: 10.1371/journal.pone.0183067] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Accepted: 07/28/2017] [Indexed: 11/18/2022] Open
Abstract
Epitope-tagging of proteins has become a widespread technique for the analysis of protein function, protein interactions and protein localization among others. Tagging of genes by chromosomal integration of PCR amplified cassettes is a widely used and fast method to label proteins in vivo. Different systems have been developed during years in the yeast Saccharomyces cerevisiae. In the present study, we analysed systematically a set of yeast proteins that were fused to different tags. Analysis of the tagged proteins revealed an unexpected general effect on protein level when some specific tagging module was used. This was due in all cases to a destabilization of the proteins and caused a reduced protein activity in the cell that was only apparent in particular conditions. Therefore, an extremely cautious approach is required when using this strategy.
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Affiliation(s)
- Sara Saiz-Baggetto
- Departament de Bioquímica i Biologia Molecular and Estructura de Recerca Interdisciplinar en Biotecnologia i Biomedicina, Universitat de València, Burjassot (Valencia), Spain
| | - Ester Méndez
- Departament de Bioquímica i Biologia Molecular and Estructura de Recerca Interdisciplinar en Biotecnologia i Biomedicina, Universitat de València, Burjassot (Valencia), Spain
| | - Inma Quilis
- Departament de Bioquímica i Biologia Molecular and Estructura de Recerca Interdisciplinar en Biotecnologia i Biomedicina, Universitat de València, Burjassot (Valencia), Spain
| | - J. Carlos Igual
- Departament de Bioquímica i Biologia Molecular and Estructura de Recerca Interdisciplinar en Biotecnologia i Biomedicina, Universitat de València, Burjassot (Valencia), Spain
- * E-mail: (JCI); (MCB)
| | - M. Carmen Bañó
- Departament de Bioquímica i Biologia Molecular and Estructura de Recerca Interdisciplinar en Biotecnologia i Biomedicina, Universitat de València, Burjassot (Valencia), Spain
- * E-mail: (JCI); (MCB)
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31
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Abstract
Sake yeast was developed exclusively in Japan. Its diversification during breeding remains largely uncharacterized. To evaluate the breeding processes of the sake lineage, we thoroughly investigated the phenotypes and differentiation of 27 sake yeast strains using high-dimensional, single-cell, morphological phenotyping. Although the genetic diversity of the sake yeast lineage is relatively low, its morphological diversity has expanded substantially compared to that of the Saccharomycescerevisiae species as a whole. Evaluation of the different types of breeding processes showed that the generation of hybrids (crossbreeding) has more profound effects on cell morphology than the isolation of mutants (mutation breeding). Analysis of phenotypic robustness revealed that some sake yeast strains are more morphologically heterogeneous, possibly due to impairment of cellular network hubs. This study provides a new perspective for studying yeast breeding genetics and micro-organism breeding strategies.
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32
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Blackford AN, Jackson SP. ATM, ATR, and DNA-PK: The Trinity at the Heart of the DNA Damage Response. Mol Cell 2017; 66:801-817. [PMID: 28622525 DOI: 10.1016/j.molcel.2017.05.015] [Citation(s) in RCA: 1206] [Impact Index Per Article: 172.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Revised: 04/28/2017] [Accepted: 05/16/2017] [Indexed: 01/09/2023]
Abstract
In vertebrate cells, the DNA damage response is controlled by three related kinases: ATM, ATR, and DNA-PK. It has been 20 years since the cloning of ATR, the last of the three to be identified. During this time, our understanding of how these kinases regulate DNA repair and associated events has grown profoundly, although major questions remain unanswered. Here, we provide a historical perspective of their discovery and discuss their established functions in sensing and responding to genotoxic stress. We also highlight what is known regarding their structural similarities and common mechanisms of regulation, as well as emerging non-canonical roles and how our knowledge of ATM, ATR, and DNA-PK is being translated to benefit human health.
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Affiliation(s)
- Andrew N Blackford
- Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, UK; Cancer Research UK and Medical Research Council Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, Oxford OX3 7DQ, UK; Wellcome Trust and Cancer Research UK Gurdon Institute, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK.
| | - Stephen P Jackson
- Wellcome Trust and Cancer Research UK Gurdon Institute, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK; Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1GA, UK.
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33
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Abstract
The accurate and complete replication of genomic DNA is essential for all life. In eukaryotic cells, the assembly of the multi-enzyme replisomes that perform replication is divided into stages that occur at distinct phases of the cell cycle. Replicative DNA helicases are loaded around origins of DNA replication exclusively during G1 phase. The loaded helicases are then activated during S phase and associate with the replicative DNA polymerases and other accessory proteins. The function of the resulting replisomes is monitored by checkpoint proteins that protect arrested replisomes and inhibit new initiation when replication is inhibited. The replisome also coordinates nucleosome disassembly, assembly, and the establishment of sister chromatid cohesion. Finally, when two replisomes converge they are disassembled. Studies in Saccharomyces cerevisiae have led the way in our understanding of these processes. Here, we review our increasingly molecular understanding of these events and their regulation.
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34
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S-phase checkpoint regulations that preserve replication and chromosome integrity upon dNTP depletion. Cell Mol Life Sci 2017; 74:2361-2380. [PMID: 28220209 PMCID: PMC5487892 DOI: 10.1007/s00018-017-2474-4] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2016] [Revised: 12/29/2016] [Accepted: 01/23/2017] [Indexed: 11/18/2022]
Abstract
DNA replication stress, an important source of genomic instability, arises upon different types of DNA replication perturbations, including those that stall replication fork progression. Inhibitors of the cellular pool of deoxynucleotide triphosphates (dNTPs) slow down DNA synthesis throughout the genome. Following depletion of dNTPs, the highly conserved replication checkpoint kinase pathway, also known as the S-phase checkpoint, preserves the functionality and structure of stalled DNA replication forks and prevents chromosome fragmentation. The underlying mechanisms involve pathways extrinsic to replication forks, such as those involving regulation of the ribonucleotide reductase activity, the temporal program of origin firing, and cell cycle transitions. In addition, the S-phase checkpoint modulates the function of replisome components to promote replication integrity. This review summarizes the various functions of the replication checkpoint in promoting replication fork stability and genome integrity in the face of replication stress caused by dNTP depletion.
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35
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Dmowski M, Rudzka J, Campbell JL, Jonczyk P, Fijałkowska IJ. Mutations in the Non-Catalytic Subunit Dpb2 of DNA Polymerase Epsilon Affect the Nrm1 Branch of the DNA Replication Checkpoint. PLoS Genet 2017; 13:e1006572. [PMID: 28107343 PMCID: PMC5291541 DOI: 10.1371/journal.pgen.1006572] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Revised: 02/03/2017] [Accepted: 01/05/2017] [Indexed: 12/14/2022] Open
Abstract
To preserve genome integrity, the S-phase checkpoint senses damaged DNA or nucleotide depletion and when necessary, arrests replication progression and delays cell division. Previous studies, based on two pol2 mutants have suggested the involvement of DNA polymerase epsilon (Pol ε) in sensing DNA replication accuracy in Saccharomyces cerevisiae. Here we have studied the involvement of Pol ε in sensing proper progression of DNA replication, using a mutant in DPB2, the gene coding for a non-catalytic subunit of Pol ε. Under genotoxic conditions, the dpb2-103 cells progress through S phase faster than wild-type cells. Moreover, the Nrm1-dependent branch of the checkpoint, which regulates the expression of many replication checkpoint genes, is impaired in dpb2-103 cells. Finally, deletion of DDC1 in the dpb2-103 mutant is lethal supporting a model of strand-specific activation of the replication checkpoint. This lethality is suppressed by NRM1 deletion. We postulate that improper activation of the Nrm1-branch may explain inefficient replication checkpoint activation in Pol ε mutants. The viability of living organisms depends on the integrity of their genomes. Each cell has to constantly monitor DNA replication and coordinate it with cell division to avoid genomic instability. This is achieved through pathways known as cell cycle checkpoints. Therefore, upon replication perturbation, DNA synthesis slows down and cell division is delayed. For that, a specific signal is induced and propagated through a mechanism that have already been identified but still need investigations. We have isolated a mutated form of Dpb2, the essential subunit of DNA polymerase epsilon (Pol ε) holoenzyme. This mutated form of Pol ε impairs proper activation of the cellular response to replication stress. We show that yeast cells with mutations in the DPB2 gene fail to activate the Nrm1-regulated branch of the checkpoint, which controls numerous genes expressed in response to replication stress. Moreover, our results support the model of parallel activation of replication checkpoint from the leading and lagging DNA strands. This strongly suggests that Pol ε, the leading strand replicase, is involved in replication checkpoint activation from this strand. Our results contribute to the understanding of mechanisms of cellular response to replication stress, which are necessary to preserve genome stability.
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Affiliation(s)
- Michał Dmowski
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences Pawińskiego 5a, Warsaw, POLAND
- * E-mail:
| | - Justyna Rudzka
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences Pawińskiego 5a, Warsaw, POLAND
| | - Judith L. Campbell
- Braun Laboratories, California Institute of Technology, Pasadena, CA, United States of America
| | - Piotr Jonczyk
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences Pawińskiego 5a, Warsaw, POLAND
| | - Iwona J. Fijałkowska
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences Pawińskiego 5a, Warsaw, POLAND
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36
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Personalised Medicine: Genome Maintenance Lessons Learned from Studies in Yeast as a Model Organism. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 1007:157-178. [PMID: 28840557 DOI: 10.1007/978-3-319-60733-7_9] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Yeast research has been tremendously contributing to the understanding of a variety of molecular pathways due to the ease of its genetic manipulation, fast doubling time as well as being cost-effective. The understanding of these pathways did not only help scientists learn more about the cellular functions but also assisted in deciphering the genetic and cellular defects behind multiple diseases. Hence, yeast research not only opened the doors for transforming basic research into applied research, but also paved the roads for improving diagnosis and innovating personalized therapy of different diseases. In this chapter, we discuss how yeast research has contributed to understanding major genome maintenance pathways such as the S-phase checkpoint activation pathways, repair via homologous recombination and non-homologous end joining as well as topoisomerases-induced protein linked DNA breaks repair. Defects in these pathways lead to neurodegenerative diseases and cancer. Thus, the understanding of the exact genetic defects underlying these diseases allowed the development of personalized medicine, improving the diagnosis and treatment and overcoming the detriments of current conventional therapies such as the side effects, toxicity as well as drug resistance.
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37
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Mec1/ATR, the Program Manager of Nucleic Acids Inc. Genes (Basel) 2016; 8:genes8010010. [PMID: 28036033 PMCID: PMC5295005 DOI: 10.3390/genes8010010] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2016] [Revised: 12/19/2016] [Accepted: 12/22/2016] [Indexed: 11/17/2022] Open
Abstract
Eukaryotic cells are equipped with surveillance mechanisms called checkpoints to ensure proper execution of cell cycle events. Among these are the checkpoints that detect DNA damage or replication perturbations and coordinate cellular activities to maintain genome stability. At the forefront of damage sensing is an evolutionarily conserved molecule, known respectively in budding yeast and humans as Mec1 (Mitosis entry checkpoint 1) and ATR (Ataxia telangiectasia and Rad3-related protein). Through phosphorylation, Mec1/ATR activates downstream components of a signaling cascade to maintain nucleotide pool balance, protect replication fork integrity, regulate activation of origins of replication, coordinate DNA repair, and implement cell cycle delay. This list of functions continues to expand as studies have revealed that Mec1/ATR modularly interacts with various protein molecules in response to different cellular cues. Among these newly assigned functions is the regulation of RNA metabolism during checkpoint activation and the coordination of replication-transcription conflicts. In this review, I will highlight some of these new functions of Mec1/ATR with a focus on the yeast model organism.
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38
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Prevention of DNA Rereplication Through a Meiotic Recombination Checkpoint Response. G3-GENES GENOMES GENETICS 2016; 6:3869-3881. [PMID: 27678521 PMCID: PMC5144958 DOI: 10.1534/g3.116.033910] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
In the budding yeast Saccharomyces cerevisiae, unnatural stabilization of the cyclin-dependent kinase inhibitor Sic1 during meiosis can trigger extra rounds of DNA replication. When programmed DNA double-strand breaks (DSBs) are generated but not repaired due to absence of DMC1, a pathway involving the checkpoint gene RAD17 prevents this DNA rereplication. Further genetic analysis has now revealed that prevention of DNA rereplication also requires MEC1, which encodes a protein kinase that serves as a central checkpoint regulator in several pathways including the meiotic recombination checkpoint response. Downstream of MEC1, MEK1 is required through its function to inhibit repair between sister chromatids. By contrast, meiotic recombination checkpoint effectors that regulate gene expression and cyclin-dependent kinase activity are not necessary. Phosphorylation of histone H2A, which is catalyzed by Mec1 and the related Tel1 protein kinase in response to DSBs, and can help coordinate activation of the Rad53 checkpoint protein kinase in the mitotic cell cycle, is required for the full checkpoint response. Phosphorylation sites that are targeted by Rad53 in a mitotic S phase checkpoint response are also involved, based on the behavior of cells containing mutations in the DBF4 and SLD3 DNA replication genes. However, RAD53 does not appear to be required, nor does RAD9, which encodes a mediator of Rad53, consistent with their lack of function in the recombination checkpoint pathway that prevents meiotic progression. While this response is similar to a checkpoint mechanism that inhibits initiation of DNA replication in the mitotic cell cycle, the evidence points to a new variation on DNA replication control.
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39
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Recovery from the DNA Replication Checkpoint. Genes (Basel) 2016; 7:genes7110094. [PMID: 27801838 PMCID: PMC5126780 DOI: 10.3390/genes7110094] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Revised: 10/20/2016] [Accepted: 10/23/2016] [Indexed: 11/17/2022] Open
Abstract
Checkpoint recovery is integral to a successful checkpoint response. Checkpoint pathways monitor progress during cell division so that in the event of an error, the checkpoint is activated to block the cell cycle and activate repair pathways. Intrinsic to this process is that once repair has been achieved, the checkpoint signaling pathway is inactivated and cell cycle progression resumes. We use the term “checkpoint recovery” to describe the pathways responsible for the inactivation of checkpoint signaling and cell cycle re-entry after the initial stress has been alleviated. The DNA replication or S-phase checkpoint monitors the integrity of DNA synthesis. When replication stress is encountered, replication forks are stalled, and the checkpoint signaling pathway is activated. Central to recovery from the S-phase checkpoint is the restart of stalled replication forks. If checkpoint recovery fails, stalled forks may become unstable and lead to DNA breaks or unusual DNA structures that are difficult to resolve, causing genomic instability. Alternatively, if cell cycle resumption mechanisms become uncoupled from checkpoint inactivation, cells with under-replicated DNA might proceed through the cell cycle, also diminishing genomic stability. In this review, we discuss the molecular mechanisms that contribute to inactivation of the S-phase checkpoint signaling pathway and the restart of replication forks during recovery from replication stress.
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40
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Almawi AW, Matthews LA, Larasati, Myrox P, Boulton S, Lai C, Moraes T, Melacini G, Ghirlando R, Duncker BP, Guarné A. 'AND' logic gates at work: Crystal structure of Rad53 bound to Dbf4 and Cdc7. Sci Rep 2016; 6:34237. [PMID: 27681475 PMCID: PMC5041073 DOI: 10.1038/srep34237] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Accepted: 09/07/2016] [Indexed: 01/07/2023] Open
Abstract
Forkhead-associated (FHA) domains are phosphopeptide recognition modules found in many signaling proteins. The Saccharomyces cerevisiae protein kinase Rad53 is a key regulator of the DNA damage checkpoint and uses its two FHA domains to interact with multiple binding partners during the checkpoint response. One of these binding partners is the Dbf4-dependent kinase (DDK), a heterodimer composed of the Cdc7 kinase and its regulatory subunit Dbf4. Binding of Rad53 to DDK, through its N-terminal FHA (FHA1) domain, ultimately inhibits DDK kinase activity, thereby preventing firing of late origins. We have previously found that the FHA1 domain of Rad53 binds simultaneously to Dbf4 and a phosphoepitope, suggesting that this domain functions as an 'AND' logic gate. Here, we present the crystal structures of the FHA1 domain of Rad53 bound to Dbf4, in the presence and absence of a Cdc7 phosphorylated peptide. Our results reveal how the FHA1 uses a canonical binding interface to recognize the Cdc7 phosphopeptide and a non-canonical interface to bind Dbf4. Based on these data we propose a mechanism to explain how Rad53 enhances the specificity of FHA1-mediated transient interactions.
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Affiliation(s)
- Ahmad W. Almawi
- Department of Biochemistry and Biomedical Sciences, ON, Canada
| | | | - Larasati
- Department of Biology, University of Waterloo, Waterloo, ON, Canada
| | - Polina Myrox
- Department of Biology, University of Waterloo, Waterloo, ON, Canada
| | - Stephen Boulton
- Department of Chemistry and Chemical Biology, McMaster University, ON, Canada
| | - Christine Lai
- Department of Biochemistry, University of Toronto, Toronto, Canada
| | - Trevor Moraes
- Department of Biochemistry, University of Toronto, Toronto, Canada
| | - Giuseppe Melacini
- Department of Chemistry and Chemical Biology, McMaster University, ON, Canada
| | - Rodolfo Ghirlando
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | | | - Alba Guarné
- Department of Biochemistry and Biomedical Sciences, ON, Canada,
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41
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Miles S, Breeden L. A common strategy for initiating the transition from proliferation to quiescence. Curr Genet 2016; 63:179-186. [PMID: 27544284 DOI: 10.1007/s00294-016-0640-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Revised: 08/04/2016] [Accepted: 08/06/2016] [Indexed: 10/21/2022]
Abstract
Development, tissue renewal and long term survival of multi-cellular organisms is dependent upon the persistence of stem cells that are quiescent, but retain the capacity to re-enter the cell cycle to self-renew, or to produce progeny that can differentiate and re-populate the tissue. Deregulated release of these cells from the quiescent state, or preventing them from entering quiescence, results in uncontrolled proliferation and cancer. Conversely, loss of quiescent cells, or their failure to re-enter cell division, disrupts organ development and prevents tissue regeneration and repair. Understanding the quiescent state and how cells control the transitions in and out of this state is of fundamental importance. Investigations into the mechanics of G1 arrest during the transition to quiescence continue to identify striking parallels between the strategies used by yeast and mammals to regulate this transition. When cells commit to a stable but reversible arrest, the G1/S genes responsible for promoting S phase must be inhibited. This process, from yeast to humans, involves the formation of quiescence-specific complexes on their promoters. In higher cells, these so-called DREAM complexes of E2F4/DP/RBL/MuvB recruit the highly conserved histone deacetylase HDAC1, which leads to local histone deacetylation and repression of S phase-promoting transcripts. Quiescent yeast cells also show pervasive histone deacetylation by the HDAC1 counterpart Rpd3. In addition, these cells contain quiescence-specific regulators of G1/S genes: Msa1 and Msa2, which can be considered components of the yeast equivalent of the DREAM complex. Despite a lack of physical similarities, the goals and the strategies used to achieve a reversible transition to quiescence are highly conserved. This motivates a detailed study of this process in the simple model organism: budding yeast.
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Affiliation(s)
- Shawna Miles
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, 1100 Fairview Ave N, Seattle, WA, 98109, USA
| | - Linda Breeden
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, 1100 Fairview Ave N, Seattle, WA, 98109, USA.
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42
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Wemhoff S, Klassen R, Beetz A, Meinhardt F. DNA Damage Responses Are Induced by tRNA Anticodon Nucleases and Hygromycin B. PLoS One 2016; 11:e0157611. [PMID: 27472060 PMCID: PMC4966947 DOI: 10.1371/journal.pone.0157611] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Accepted: 06/01/2016] [Indexed: 12/26/2022] Open
Abstract
Previous studies revealed DNA damage to occur during the toxic action of PaT, a fungal anticodon ribonuclease (ACNase) targeting the translation machinery via tRNA cleavage. Here, we demonstrate that other translational stressors induce DNA damage-like responses in yeast as well: not only zymocin, another ACNase from the dairy yeast Kluyveromyces lactis, but also translational antibiotics, most pronouncedly hygromycin B (HygB). Specifically, DNA repair mechanisms BER (base excision repair), HR (homologous recombination) and PRR (post replication repair) provided protection, whereas NHEJ (non-homologous end-joining) aggravated toxicity of all translational inhibitors. Analysis of specific BER mutants disclosed a strong HygB, zymocin and PaT protective effect of the endonucleases acting on apurinic sites. In cells defective in AP endonucleases, inactivation of the DNA glycosylase Ung1 increased tolerance to ACNases and HygB. In addition, Mag1 specifically contributes to the repair of DNA lesions caused by HygB. Consistent with DNA damage provoked by translation inhibitors, mutation frequencies were elevated upon exposure to both fungal ACNases and HygB. Since polymerase ζ contributed to toxicity in all instances, error-prone lesion-bypass probably accounts for the mutagenic effects. The finding that differently acting inhibitors of protein biosynthesis induce alike cellular responses in DNA repair mutants is novel and suggests the dependency of genome stability on translational fidelity.
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Affiliation(s)
- Sabrina Wemhoff
- Institut für Molekulare Mikrobiologie und Biotechnologie, Westfälische Wilhelms-Universität Münster, Münster, Germany
| | - Roland Klassen
- Institut für Biologie, Fachgebiet Mikrobiologie, Universität Kassel, Kassel, Germany
| | - Anja Beetz
- Institut für Molekulare Mikrobiologie und Biotechnologie, Westfälische Wilhelms-Universität Münster, Münster, Germany
| | - Friedhelm Meinhardt
- Institut für Molekulare Mikrobiologie und Biotechnologie, Westfälische Wilhelms-Universität Münster, Münster, Germany
- * E-mail:
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43
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Profiling DNA damage-induced phosphorylation in budding yeast reveals diverse signaling networks. Proc Natl Acad Sci U S A 2016; 113:E3667-75. [PMID: 27298372 DOI: 10.1073/pnas.1602827113] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The DNA damage response (DDR) is regulated by a protein kinase signaling cascade that orchestrates DNA repair and other processes. Identifying the substrate effectors of these kinases is critical for understanding the underlying physiology and mechanism of the response. We have used quantitative mass spectrometry to profile DDR-dependent phosphorylation in budding yeast and genetically explored the dependency of these phosphorylation events on the DDR kinases MEC1, RAD53, CHK1, and DUN1. Based on these screens, a database containing many novel DDR-regulated phosphorylation events has been established. Phosphorylation of many of these proteins has been validated by quantitative peptide phospho-immunoprecipitation and examined for functional relevance to the DDR through large-scale analysis of sensitivity to DNA damage in yeast deletion strains. We reveal a link between DDR signaling and the metabolic pathways of inositol phosphate and phosphatidyl inositol synthesis, which are required for resistance to DNA damage. We also uncover links between the DDR and TOR signaling as well as translation regulation. Taken together, these data shed new light on the organization of DDR signaling in budding yeast.
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Miles S, Croxford MW, Abeysinghe AP, Breeden LL. Msa1 and Msa2 Modulate G1-Specific Transcription to Promote G1 Arrest and the Transition to Quiescence in Budding Yeast. PLoS Genet 2016; 12:e1006088. [PMID: 27272642 PMCID: PMC4894574 DOI: 10.1371/journal.pgen.1006088] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Accepted: 05/09/2016] [Indexed: 12/23/2022] Open
Abstract
Yeast that naturally exhaust their glucose source can enter a quiescent state that is characterized by reduced cell size, and high cell density, stress tolerance and longevity. The transition to quiescence involves highly asymmetric cell divisions, dramatic reprogramming of transcription and global changes in chromatin structure and chromosome topology. Cells enter quiescence from G1 and we find that there is a positive correlation between the length of G1 and the yield of quiescent cells. The Swi4 and Swi6 transcription factors, which form the SBF transcription complex and promote the G1 to S transition in cycling cells, are also critical for the transition to quiescence. Swi6 forms a second complex with Mbp1 (MBF), which is not required for quiescence. These are the functional analogues of the E2F complexes of higher eukaryotes. Loss of the RB analogue, Whi5, and the related protein Srl3/Whi7, delays G1 arrest, but it also delays recovery from quiescence. Two MBF- and SBF-Associated proteins have been identified that have little effect on SBF or MBF activity in cycling cells. We show that these two related proteins, Msa1 and Msa2, are specifically required for the transition to quiescence. Like the E2F complexes that are quiescence-specific, Msa1 and Msa2 are required to repress the transcription of many SBF target genes, including SWI4, the CLN2 cyclin and histones, specifically after glucose is exhausted from the media. They also activate transcription of many MBF target genes. msa1msa2 cells fail to G1 arrest and rapidly lose viability upon glucose exhaustion. msa1msa2 mutants that survive this transition are very large, but they attain the same thermo-tolerance and longevity of wild type quiescent cells. This indicates that Msa1 and Msa2 are required for successful transition to quiescence, but not for the maintenance of that state. In spite of the many differences between yeast and humans, the basic strategies that regulate the cell division cycle are fundamentally conserved. In this study, we extend these parallels to include a common strategy by which cells transition from proliferation to quiescence. The decision to divide is made in the G1 phase of the cell cycle. During G1, the genes that drive DNA replication are repressed by the E2F/RB complex. When a signal to divide is received, RB is removed and the complex is activated. When cells commit to a long term, but reversible G1 arrest, or quiescence, they express a novel E2F/RB-like complex, which promotes and maintains a stable repressive state. Yeast cells contain a functional analog of E2F/RB, called SBF/Whi5, which is activated by a similar mechanism in proliferating yeast cells. In this study, we identify two novel components of the SBF/Whi5 complex whose activity is specific to the transition to quiescence. These factors, Msa1 and Msa2, repress SBF targets and are required for the long term, but reversible G1 arrest that is critical for achieving a quiescent state.
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Affiliation(s)
- Shawna Miles
- Basic Science Division, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
| | - Matthew W Croxford
- Basic Science Division, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
| | - Amali P Abeysinghe
- Basic Science Division, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
| | - Linda L Breeden
- Basic Science Division, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
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Goshima T, Nakamura R, Kume K, Okada H, Ichikawa E, Tamura H, Hasuda H, Inahashi M, Okazaki N, Akao T, Shimoi H, Mizunuma M, Ohya Y, Hirata D. Identification of a mutation causing a defective spindle assembly checkpoint in high ethyl caproate-producing sake yeast strain K1801. Biosci Biotechnol Biochem 2016; 80:1657-62. [PMID: 27191586 DOI: 10.1080/09168451.2016.1184963] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
In high-quality sake brewing, the cerulenin-resistant sake yeast K1801 with high ethyl caproate-producing ability has been used widely; however, K1801 has a defective spindle assembly checkpoint (SAC). To identify the mutation causing this defect, we first searched for sake yeasts with a SAC-defect like K1801 and found that K13 had such a defect. Then, we searched for a common SNP in only K1801 and K13 by examining 15 checkpoint-related genes in 23 sake yeasts, and found 1 mutation, R48P of Cdc55, the PP2A regulatory B subunit that is important for the SAC. Furthermore, we confirmed that the Cdc55-R48P mutation was responsible for the SAC-defect in K1801 by molecular genetic analyses. Morphological analysis indicated that this mutation caused a high cell morphological variation. But this mutation did not affect the excellent brewing properties of K1801. Thus, this mutation is a target for breeding of a new risk-free K1801 with normal checkpoint integrity.
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Affiliation(s)
- Tetsuya Goshima
- a National Research Institute of Brewing , Higashi-Hiroshima , Japan
| | - Ryo Nakamura
- b Research and Development Department , Asahi Sake Brewing Co. Ltd. , Nagaoka , Niigata , Japan.,c Department of Molecular Biotechnology , Graduate School of Advanced Sciences of Matter, Hiroshima University , Higashi-Hiroshima , Japan
| | - Kazunori Kume
- c Department of Molecular Biotechnology , Graduate School of Advanced Sciences of Matter, Hiroshima University , Higashi-Hiroshima , Japan
| | - Hiroki Okada
- d Department of Integrated Biosciences, Graduate School of Frontier Sciences , The University of Tokyo , Kashiwa , Chiba , Japan.,e Department of Cell and Developmental Biology, Perelman School of Medicine , University of Pennsylvania , Philadelphia , PA , USA
| | - Eri Ichikawa
- b Research and Development Department , Asahi Sake Brewing Co. Ltd. , Nagaoka , Niigata , Japan
| | - Hiroyasu Tamura
- b Research and Development Department , Asahi Sake Brewing Co. Ltd. , Nagaoka , Niigata , Japan
| | | | | | - Naoto Okazaki
- f Brewing Society of Japan , Kita-ku , Tokyo , Japan
| | - Takeshi Akao
- a National Research Institute of Brewing , Higashi-Hiroshima , Japan
| | - Hitoshi Shimoi
- g Department of Biological Chemistry and Food Sciences , Iwate University , Morioka , Iwate , Japan
| | - Masaki Mizunuma
- c Department of Molecular Biotechnology , Graduate School of Advanced Sciences of Matter, Hiroshima University , Higashi-Hiroshima , Japan
| | - Yoshikazu Ohya
- d Department of Integrated Biosciences, Graduate School of Frontier Sciences , The University of Tokyo , Kashiwa , Chiba , Japan
| | - Dai Hirata
- b Research and Development Department , Asahi Sake Brewing Co. Ltd. , Nagaoka , Niigata , Japan.,c Department of Molecular Biotechnology , Graduate School of Advanced Sciences of Matter, Hiroshima University , Higashi-Hiroshima , Japan
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Abstract
This year's Albert Lasker Basic Medical Research Award honors Evelyn Witkin and Stephen J. Elledge, two pioneers in elucidating the DNA damage response, whose contributions span more than 40 years.
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Affiliation(s)
- James E Haber
- Department of Biology and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, MA 02454, USA.
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47
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Earp C, Rowbotham S, Merényi G, Chabes A, Cha RS. S phase block following MEC1ATR inactivation occurs without severe dNTP depletion. Biol Open 2015; 4:1739-43. [PMID: 26603472 PMCID: PMC4736042 DOI: 10.1242/bio.015347] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Inactivation of Mec1, the budding yeast ATR, results in a permanent S phase arrest followed by chromosome breakage and cell death during G2/M. The S phase arrest is proposed to stem from a defect in Mec1-mediated degradation of Sml1, a conserved inhibitor of ribonucleotide reductase (RNR), causing a severe depletion in cellular dNTP pools. Here, the casual link between the S phase arrest, Sml1, and dNTP-levels is examined using a temperature sensitive mec1 mutant. In addition to S phase arrest, thermal inactivation of Mec1 leads to constitutively high levels of Sml1 and an S phase arrest. Expression of a novel suppressor, GIS2, a conserved mRNA binding zinc finger protein, rescues the arrest without down-regulating Sml1 levels. The dNTP pool in mec1 is reduced by ∼17% and GIS2 expression restores it, but only partially, to ∼93% of a control. We infer that the permanent S phase block following Mec1 inactivation can be uncoupled from its role in Sml1 down-regulation. Furthermore, unexpectedly modest effects of mec1 and GIS2 on dNTP levels suggest that the S phase arrest is unlikely to result from a severe depletion of dNTP pool as assumed, but a heightened sensitivity to small changes in its availability. Summary: This study, using a temperature sensitive mec1 mutant, reveals that inactivation of Mec1 leads to S phase arrest, and that genome duplication in the absence of Mec1/ATR is exquisitely sensitive to small changes in dNTP levels.
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Affiliation(s)
- Caroline Earp
- Stem Cell Biology and Developmental Genetics, National Institute for Medical Research, MRC, London NW7 1AA, UK
| | - Samuel Rowbotham
- Stem Cell Biology and Developmental Genetics, National Institute for Medical Research, MRC, London NW7 1AA, UK
| | - Gábor Merényi
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå SE 901 87, Sweden
| | - Andrei Chabes
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå SE 901 87, Sweden
| | - Rita S Cha
- Stem Cell Biology and Developmental Genetics, National Institute for Medical Research, MRC, London NW7 1AA, UK North West Cancer Research Institute, School of Medical Sciences, Bangor University, Bangor LL57 2UW, UK
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Lafon A, Taranum S, Pietrocola F, Dingli F, Loew D, Brahma S, Bartholomew B, Papamichos-Chronakis M. INO80 Chromatin Remodeler Facilitates Release of RNA Polymerase II from Chromatin for Ubiquitin-Mediated Proteasomal Degradation. Mol Cell 2015; 60:784-796. [PMID: 26656161 DOI: 10.1016/j.molcel.2015.10.028] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Revised: 08/17/2015] [Accepted: 10/14/2015] [Indexed: 12/13/2022]
Abstract
Stalling of RNA Polymerase II (RNAPII) on chromatin during transcriptional stress results in polyubiquitination and degradation of the largest subunit of RNAPII, Rpb1, by the ubiquitin proteasome system (UPS). Here, we report that the ATP-dependent chromatin remodeling complex INO80 is required for turnover of chromatin-bound RNAPII in yeast. INO80 interacts physically and functionally with Cdc48/p97/VCP, a component of UPS required for degradation of RNAPII. Cells lacking INO80 are defective in Rpb1 degradation and accumulate tightly bound ubiquitinated Rpb1 on chromatin. INO80 forms a ternary complex with RNAPII and Cdc48 and targets Rpb1 primed for degradation. The function of INO80 in RNAPII turnover is required for cell growth and survival during genotoxic stress. Our results identify INO80 as a bona fide component of the proteolytic pathway for RNAPII degradation and suggest that INO80 nucleosome remodeling activity promotes the dissociation of ubiquitinated Rpb1 from chromatin to protect the integrity of the genome.
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Affiliation(s)
- Anne Lafon
- Institut Curie, PSL Research University, CNRS, UMR3664, 26 rue d'Ulm, 75248 Paris, France
| | - Surayya Taranum
- Institut Curie, PSL Research University, CNRS, UMR3664, 26 rue d'Ulm, 75248 Paris, France
| | - Federico Pietrocola
- Institut Curie, PSL Research University, CNRS, UMR3664, 26 rue d'Ulm, 75248 Paris, France
| | - Florent Dingli
- Institut Curie, PSL Research University, Laboratory of Proteomics and Mass Spectrometry, 26 rue d'Ulm, 75248 Paris, France
| | - Damarys Loew
- Institut Curie, PSL Research University, Laboratory of Proteomics and Mass Spectrometry, 26 rue d'Ulm, 75248 Paris, France
| | - Sandipan Brahma
- UT MD Anderson Cancer Center, Science Park, 1808 Park Road 1C, Smithville, TX 78957, USA
| | - Blaine Bartholomew
- UT MD Anderson Cancer Center, Science Park, 1808 Park Road 1C, Smithville, TX 78957, USA
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49
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Cortez D, Zhou Z, Sanchez Y. Stephen Elledge and the DNA damage response. DNA Repair (Amst) 2015; 35:156-7. [PMID: 26574138 DOI: 10.1016/j.dnarep.2015.11.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Affiliation(s)
- David Cortez
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232, United States.
| | - Zheng Zhou
- Department of Biochemistry & Molecular Biology, Baylor College of Medicine, Houston, TX 77030, United States
| | - Yolanda Sanchez
- Department of Pharmacology and Toxicology, Geisel School of Medicine, Dartmouth College, Hanover, NH 03755, United States; Dartmouth-Hitchcock Norris Cotton Cancer Center, Lebanon, NH 03756, United States
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50
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Jackson S. Evelyn Witkin and Stephen Elledge share the 2015 Lasker Basic Medical Award. J Clin Invest 2015; 125:3727-31. [PMID: 26345423 DOI: 10.1172/jci84318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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