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Yang B, Lin Y, Huang Y, Shen YQ, Chen Q. Thioredoxin (Trx): A redox target and modulator of cellular senescence and aging-related diseases. Redox Biol 2024; 70:103032. [PMID: 38232457 PMCID: PMC10827563 DOI: 10.1016/j.redox.2024.103032] [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: 10/14/2023] [Revised: 12/03/2023] [Accepted: 01/04/2024] [Indexed: 01/19/2024] Open
Abstract
Thioredoxin (Trx) is a compact redox-regulatory protein that modulates cellular redox state by reducing oxidized proteins. Trx exhibits dual functionality as an antioxidant and a cofactor for diverse enzymes and transcription factors, thereby exerting influence over their activity and function. Trx has emerged as a pivotal biomarker for various diseases, particularly those associated with oxidative stress, inflammation, and aging. Recent clinical investigations have underscored the significance of Trx in disease diagnosis, treatment, and mechanistic elucidation. Despite its paramount importance, the intricate interplay between Trx and cellular senescence-a condition characterized by irreversible growth arrest induced by multiple aging stimuli-remains inadequately understood. In this review, our objective is to present a comprehensive and up-to-date overview of the structure and function of Trx, its involvement in redox signaling pathways and cellular senescence, its association with aging and age-related diseases, as well as its potential as a therapeutic target. Our review aims to elucidate the novel and extensive role of Trx in senescence while highlighting its implications for aging and age-related diseases.
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Affiliation(s)
- Bowen Yang
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, Chinese Academy of Medical Sciences Research Unit of Oral Carcinogenesis and Management, West China Hospital of Stomatology, Sichuan University, Chengdu, 610041, China.
| | - Yumeng Lin
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, Chinese Academy of Medical Sciences Research Unit of Oral Carcinogenesis and Management, West China Hospital of Stomatology, Sichuan University, Chengdu, 610041, China.
| | - Yibo Huang
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, Chinese Academy of Medical Sciences Research Unit of Oral Carcinogenesis and Management, West China Hospital of Stomatology, Sichuan University, Chengdu, 610041, China.
| | - Ying-Qiang Shen
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, Chinese Academy of Medical Sciences Research Unit of Oral Carcinogenesis and Management, West China Hospital of Stomatology, Sichuan University, Chengdu, 610041, China.
| | - Qianming Chen
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, Chinese Academy of Medical Sciences Research Unit of Oral Carcinogenesis and Management, West China Hospital of Stomatology, Sichuan University, Chengdu, 610041, China
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Creamer KM, Kolpa HJ, Lawrence JB. Nascent RNA scaffolds contribute to chromosome territory architecture and counter chromatin compaction. Mol Cell 2021; 81:3509-3525.e5. [PMID: 34320406 DOI: 10.1016/j.molcel.2021.07.004] [Citation(s) in RCA: 50] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2021] [Revised: 07/06/2021] [Accepted: 07/06/2021] [Indexed: 12/17/2022]
Abstract
Nuclear chromosomes transcribe far more RNA than required to encode protein. Here we investigate whether non-coding RNA broadly contributes to cytological-scale chromosome territory architecture. We develop a procedure that depletes soluble proteins, chromatin, and most nuclear RNA from the nucleus but does not delocalize XIST, a known architectural RNA, from an insoluble chromosome "scaffold." RNA-seq analysis reveals that most RNA in the nuclear scaffold is repeat-rich, non-coding, and derived predominantly from introns of nascent transcripts. Insoluble, repeat-rich (C0T-1) RNA co-distributes with known scaffold proteins including scaffold attachment factor A (SAF-A), and distribution of these components inversely correlates with chromatin compaction in normal and experimentally manipulated nuclei. We further show that RNA is required for SAF-A to interact with chromatin and for enrichment of structurally embedded "scaffold attachment regions" prevalent in euchromatin. Collectively, the results indicate that long nascent transcripts contribute a dynamic structural role that promotes the open architecture of active chromosome territories.
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Affiliation(s)
- Kevin Michael Creamer
- Department of Neurology and Pediatrics, University of Massachusetts Medical School, 55 Lake Avenue North, Worcester, MA 01655, USA
| | - Heather Jill Kolpa
- Department of Neurology and Pediatrics, University of Massachusetts Medical School, 55 Lake Avenue North, Worcester, MA 01655, USA
| | - Jeanne Bentley Lawrence
- Department of Neurology and Pediatrics, University of Massachusetts Medical School, 55 Lake Avenue North, Worcester, MA 01655, USA.
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Maintenance of epigenetic landscape requires CIZ1 and is corrupted in differentiated fibroblasts in long-term culture. Nat Commun 2019; 10:460. [PMID: 30692537 PMCID: PMC6484225 DOI: 10.1038/s41467-018-08072-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Accepted: 12/04/2018] [Indexed: 01/09/2023] Open
Abstract
The inactive X chromosome (Xi) serves as a model for establishment and maintenance of repressed chromatin and the function of polycomb repressive complexes (PRC1/2). Here we show that Xi transiently relocates from the nuclear periphery towards the interior during its replication, in a process dependent on CIZ1. Compromised relocation of Xi in CIZ1-null primary mouse embryonic fibroblasts is accompanied by loss of PRC-mediated H2AK119Ub1 and H3K27me3, increased solubility of PRC2 catalytic subunit EZH2, and genome-wide deregulation of polycomb-regulated genes. Xi position in S phase is also corrupted in cells adapted to long-term culture (WT or CIZ1-null), and also accompanied by specific changes in EZH2 and its targets. The data are consistent with the idea that chromatin relocation during S phase contributes to maintenance of epigenetic landscape in primary cells, and that elevated soluble EZH2 is part of an error-prone mechanism by which modifying enzyme meets template when chromatin relocation is compromised. The inactive X chromosome (Xi) is a model for establishment and maintenance of repressed chromatin and the function of polycomb repressive complexes. Here the authors show that Xi transiently relocates from the nuclear periphery during replication in a CIZ1-dependent manner, which plays a role in maintaining PRC-mediated repressed chromatin.
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Kucherlapati M. Examining transcriptional changes to DNA replication and repair factors over uveal melanoma subtypes. BMC Cancer 2018; 18:818. [PMID: 30107825 PMCID: PMC6092802 DOI: 10.1186/s12885-018-4705-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Accepted: 07/30/2018] [Indexed: 12/20/2022] Open
Abstract
Background Uncontrolled replication is a process common to all cancers facilitated by the summation of changes accumulated as tumors progress. The aim of this study was to examine small groups of genes with known biology in replication and repair at the transcriptional and genomic levels, correlating alterations with survival in uveal melanoma tumor progression. Selected components of Pre-Replication, Pre-Initiation, and Replisome Complexes, DNA Damage Response and Mismatch Repair have been observed. Methods Two groups have been generated for selected genes above and below the average alteration level and compared for expression and survival across The Cancer Genome Atlas uveal melanoma subtypes. Significant differences in expression between subtypes monosomic or disomic for chromosome 3 have been identified by Fisher’s exact test. Kaplan Meier survival distribution based on disease specific survival has been compared by Log-rank test. Results Genes with significant alteration include MCM2, MCM4, MCM5, CDC45, MCM10, CIZ1, PCNA, FEN1, LIG1, POLD1, POLE, HUS1, CHECK1, ATRIP, MLH3, and MSH6. Exon 4 skipping in CIZ1 previously identified as a cancer variant, and reportedly used as an early serum biomarker in lung cancer was found. Mismatch Repair protein MLH3 was found to have splicing variations with deletions to both Exon 5 and Exon 7 simultaneously. PCNA, FEN1, and LIG1 had increased relative expression levels not due to mutation or to copy number variation. Conclusion The current study proposes changes in relative and differential expression to replication and repair genes that support the concept their products are causally involved in uveal melanoma. Specific avenues for early biomarker identification and therapeutic approach are suggested.
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Affiliation(s)
- Melanie Kucherlapati
- Department of Genetics, Harvard Medical School, Boston, 02115, MA, USA. .,Department of Medicine, Division of Genetics, Brigham and Women's Hospital, 77 Avenue Louis Pasteur NRB 160B, Boston, 02115, MA, USA.
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Transformation-induced changes in the DNA-nuclear matrix interface, revealed by high-throughput analysis of DNA halos. Sci Rep 2017; 7:6475. [PMID: 28743923 PMCID: PMC5526987 DOI: 10.1038/s41598-017-06459-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Accepted: 06/13/2017] [Indexed: 01/22/2023] Open
Abstract
In higher eukaryotic nuclei, DNA is periodically anchored to an extraction-resistant protein structure, via matrix attachment regions. We describe a refined and accessible method to non-subjectively, rapidly and reproducibly measure both size and stability of the intervening chromatin loops, and use it to demonstrate that malignant transformation compromises the DNA-nuclear matrix interface.
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Emerging Roles for Ciz1 in Cell Cycle Regulation and as a Driver of Tumorigenesis. Biomolecules 2016; 7:biom7010001. [PMID: 28036012 PMCID: PMC5372713 DOI: 10.3390/biom7010001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Revised: 12/12/2016] [Accepted: 12/14/2016] [Indexed: 12/19/2022] Open
Abstract
Precise duplication of the genome is a prerequisite for the health and longevity of multicellular organisms. The temporal regulation of origin specification, replication licensing, and firing at replication origins is mediated by the cyclin-dependent kinases. Here the role of Cip1 interacting Zinc finger protein 1 (Ciz1) in regulation of cell cycle progression is discussed. Ciz1 contributes to regulation of the G1/S transition in mammalian cells. Ciz1 contacts the pre-replication complex (pre-RC) through cell division cycle 6 (Cdc6) interactions and aids localization of cyclin A- cyclin-dependent kinase 2 (CDK2) activity to chromatin and the nuclear matrix during initiation of DNA replication. We discuss evidence that Ciz1 serves as a kinase sensor that regulates both initiation of DNA replication and prevention of re-replication. Finally, the emerging role for Ciz1 in cancer biology is discussed. Ciz1 is overexpressed in common tumors and tumor growth is dependent on Ciz1 expression, suggesting that Ciz1 is a driver of tumor growth. We present evidence that Ciz1 may contribute to deregulation of the cell cycle due to its ability to alter the CDK activity thresholds that are permissive for initiation of DNA replication. We propose that Ciz1 may contribute to oncogenesis by induction of DNA replication stress and that Ciz1 may be a multifaceted target in cancer therapy.
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Wilson RHC, Hesketh EL, Coverley D. The Nuclear Matrix: Fractionation Techniques and Analysis. Cold Spring Harb Protoc 2016; 2016:pdb.top074518. [PMID: 26729911 DOI: 10.1101/pdb.top074518] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The first descriptions of an insoluble nuclear structure appeared more than 70 years ago, but it is only in recent years that a sophisticated picture of its significance has begun to emerge. Here we introduce multiple methods for the study of the nuclear matrix.
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Affiliation(s)
| | - Emma L Hesketh
- Department of Biology, University of York, York YO10 5DD, United Kingdom
| | - Dawn Coverley
- Department of Biology, University of York, York YO10 5DD, United Kingdom
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Wilson RHC, Hesketh EL, Coverley D. Preparation of the Nuclear Matrix for Parallel Microscopy and Biochemical Analyses. Cold Spring Harb Protoc 2016; 2016:pdb.prot083758. [PMID: 26729903 DOI: 10.1101/pdb.prot083758] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Immobilized proteins within the nucleus are usually identified by treating cells with detergent. The detergent-resistant fraction is often assumed to be chromatin and is described as such in many studies. However, this fraction consists of both chromatin-bound and nuclear-matrix-bound proteins. To investigate nuclear-matrix-bound proteins alone, further separation of these fractions is required; the DNA must be removed so that the remaining proteins can be compared with those from untreated cells. This protocol uses a nonionic detergent (Triton X-100) to remove membranes and soluble proteins from cells under physiologically relevant salt concentrations, followed by extraction with 0.5 m NaCl, digestion with DNase I, and removal of fragmented DNA. It uses a specialized buffer (cytoskeletal buffer) to stabilize the cytoskeleton and nuclear matrix in relatively gentle conditions. Nuclear matrix proteins can then be assessed by either immunofluorescence (IF) and immunoblotting (IB). IB has the advantage of resolving different forms of a protein of interest, and the soluble fractions can be analyzed. The major advantage of IF analysis is that individual cells (rather than homogenized populations) can be monitored, and the spatial arrangement of proteins bound to residual nuclear structures can be revealed.
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Affiliation(s)
- Rosemary H C Wilson
- Department of Biology, University of York, Wentworth Way, York YO10 5DD, United Kingdom
| | - Emma L Hesketh
- Department of Biology, University of York, Wentworth Way, York YO10 5DD, United Kingdom
| | - Dawn Coverley
- Department of Biology, University of York, Wentworth Way, York YO10 5DD, United Kingdom
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Hesketh EL, Knight JRP, Wilson RHC, Chong JPJ, Coverley D. Transient association of MCM complex proteins with the nuclear matrix during initiation of mammalian DNA replication. Cell Cycle 2015; 14:333-41. [PMID: 25659032 DOI: 10.4161/15384101.2014.980647] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The minichromosome maintenance complex (MCM2-7) is the putative DNA helicase in eukaryotes, and essential for DNA replication. By applying serial extractions to mammalian cells synchronized by release from quiescence, we reveal dynamic changes to the sub-nuclear compartmentalization of MCM2 as cells pass through late G1 and early S phase, identifying a brief window when MCM2 becomes transiently attached to the nuclear-matrix. The data distinguish 3 states that correspond to loose association with chromatin prior to DNA replication, transient highly stable binding to the nuclear-matrix coincident with initiation, and a post-initiation phase when MCM2 remains tightly associated with chromatin but not the nuclear-matrix. The data suggests that functional MCM complex loading takes place at the nuclear-matrix.
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Affiliation(s)
- Emma L Hesketh
- a Department of Biology ; University of York ; York , UK
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Hesketh EL, Parker-Manuel RP, Chaban Y, Satti R, Coverley D, Orlova EV, Chong JPJ. DNA induces conformational changes in a recombinant human minichromosome maintenance complex. J Biol Chem 2015; 290:7973-9. [PMID: 25648893 PMCID: PMC4367295 DOI: 10.1074/jbc.m114.622738] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Revised: 02/02/2015] [Indexed: 11/30/2022] Open
Abstract
ATP-dependent DNA unwinding activity has been demonstrated for recombinant archaeal homohexameric minichromosome maintenance (MCM) complexes and their yeast heterohexameric counterparts, but in higher eukaryotes such as Drosophila, MCM-associated DNA helicase activity has been observed only in the context of a co-purified Cdc45-MCM-GINS complex. Here, we describe the production of the recombinant human MCM (hMCM) complex in Escherichia coli. This protein displays ATP hydrolysis activity and is capable of unwinding duplex DNA. Using single-particle asymmetric EM reconstruction, we demonstrate that recombinant hMCM forms a hexamer that undergoes a conformational change when bound to DNA. Recombinant hMCM produced without post-translational modifications is functional in vitro and provides an important tool for biochemical reconstitution of the human replicative helicase.
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Affiliation(s)
- Emma L Hesketh
- From the Department of Biology, University of York, York YO10 5DD and
| | | | - Yuriy Chaban
- the Department of Crystallography, Birkbeck College London, London WC1E 7HX, United Kingdom
| | - Rabab Satti
- From the Department of Biology, University of York, York YO10 5DD and
| | - Dawn Coverley
- From the Department of Biology, University of York, York YO10 5DD and
| | - Elena V Orlova
- the Department of Crystallography, Birkbeck College London, London WC1E 7HX, United Kingdom
| | - James P J Chong
- From the Department of Biology, University of York, York YO10 5DD and
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Copeland NA, Sercombe HE, Wilson RHC, Coverley D. Cyclin A/CDK2 phosphorylation of CIZ1 blocks replisome formation and initiation of mammalian DNA replication. J Cell Sci 2015; 128:1518-27. [DOI: 10.1242/jcs.161919] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2014] [Accepted: 02/23/2015] [Indexed: 12/25/2022] Open
Abstract
CIZ1 is a nuclear matrix protein that cooperates with cyclin A/CDK2 to promote mammalian DNA replication. We show here that cyclin A/CDK2 also negatively regulates CIZ1 activity via phosphorylation at threonines 144, 192, and 293. Phosphomimetic mutants do not promote DNA replication in cell-free and cell-based assays, and also have a dominant negative effect on replisome formation at the level of PCNA recruitment. Phosphorylation blocks direct interaction with cyclin A/CDK2, and recruitment of endogenous cyclin A to the nuclear matrix. In contrast, phosphomimetic CIZ1 retains nuclear matrix binding capability, and interaction with CDC6 is not affected. Phospho-threonine 192-specific antibodies confirm that CIZ1 is phosphorylated during S-phase and G2, and show that phosphorylation at this site occurs at post-initiation concentrations of cyclin A/CDK2. Together the data suggest that CIZ1 is a kinase sensor that promotes initiation of DNA replication at low kinase levels, when in a hypophosphorylated state that is permissive for cyclin A-CDK2 interaction and delivery to licensed origins, but blocks delivery at higher kinase levels when it is itself phosphorylated.
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Munkley J, Rajan P, Laferty NP, Dalgliesh C, Jackson RM, Robson CN, Leung HY, Elliott DJ. A novel androgen-regulated isoform of the TSC2 tumour suppressor gene increases cell proliferation. Oncotarget 2014; 5:131-9. [PMID: 24318044 PMCID: PMC3960195 DOI: 10.18632/oncotarget.1405] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2013] [Accepted: 10/19/2013] [Indexed: 01/07/2023] Open
Abstract
TSC2 (Tuberous sclerosis complex 2) is an important tumour suppressor gene, mutations within which are linked to the development of tuberous sclerosis and implicated in multiple tumour types. TSC2 protein complexes with TSC1 and blocks the ability of the Rheb (Ras homolog enriched in brain) GTPase to activate mTOR (mammalian target of rapamycin), a crucial signal transducer which regulates protein synthesis and cell growth. Here, we report the characterisation of a novel isoform of TSC2 which is under direct control of the ligand-activated androgen receptor. TSC2 isoform A (TSC2A) is derived from an internal androgen-regulated alternative promoter and encodes a 508-amino acid cytoplasmic protein corresponding to the C-terminal region of full-length TSC2, lacking the interaction domain for TSC1 and containing an incomplete interaction domain required for Rheb inactivation. Expression of TSC2A is induced in response to androgens and full-length TSC2 is co-ordinately down-regulated, indicating an androgen-driven switch in TSC2 protein isoforms. In contrast to the well-characterised suppressive effect on cell proliferation of full-length TSC2 protein, both LNCaP and HEK293 cells over-expressing TSC2 isoform A proliferate more rapidly (measured by MTT assays) and have increased levels of cells in S-phase (measured by both Edu staining and FACS analysis). Our work indicates, for the first time, a novel role for this well-known tumour suppressor gene, which encodes an activator of cell proliferation in response to androgen stimulation.
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Affiliation(s)
- Jennifer Munkley
- Institute of Genetic Medicine, Newcastle University, Newcastle-upon-Tyne, United Kingdom
| | - Prabhakar Rajan
- Beatson Institute for Cancer Research, Glasgow, United Kingdom
- Institute of Cancer Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Nicholas P. Laferty
- Institute of Genetic Medicine, Newcastle University, Newcastle-upon-Tyne, United Kingdom
| | - Caroline Dalgliesh
- Institute of Genetic Medicine, Newcastle University, Newcastle-upon-Tyne, United Kingdom
| | - Robert M. Jackson
- Institute of Genetic Medicine, Newcastle University, Newcastle-upon-Tyne, United Kingdom
| | - Craig N. Robson
- Northern Institute for Cancer Research, Newcastle University, Newcastle-upon-Tyne, United Kingdom
| | - Hing Y. Leung
- Beatson Institute for Cancer Research, Glasgow, United Kingdom
- Institute of Cancer Sciences, University of Glasgow, Glasgow, United Kingdom
| | - David J. Elliott
- Institute of Genetic Medicine, Newcastle University, Newcastle-upon-Tyne, United Kingdom
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Wilson RHC, Coverley D. Relationship between DNA replication and the nuclear matrix. Genes Cells 2012; 18:17-31. [PMID: 23134523 PMCID: PMC3564400 DOI: 10.1111/gtc.12010] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2012] [Accepted: 09/10/2012] [Indexed: 01/24/2023]
Abstract
There is an extensive list of primary published work related to the nuclear matrix (NM). Here we review the aspects that are required to understand its relationship with DNA replication, while highlighting some of the difficulties in studying such a structure, and possible differences that arise from the choice of model system. We consider NM attachment regions of DNA and discuss their characteristics and potential function before reviewing data that deal specifically with functional interaction with DNA replication factors. Data have long existed indicating that newly synthesized DNA is associated with a nuclease-resistant NM, allowing the conclusion that the elongation step of DNA synthesis is immobilized within the nucleus. We review in more detail the emerging data that suggest that prereplication complex proteins and origins of replication are transiently recruited to the NM during late G1 and early S-phase. Collectively, these data suggest that the initiation step of the DNA replication process is also immobilized by attachment to the NM. We outline models that discuss the possible spatial relationships and highlight the emerging evidence that suggests there may be important differences between cell types.
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Variant Ciz1 is a circulating biomarker for early-stage lung cancer. Proc Natl Acad Sci U S A 2012; 109:E3128-35. [PMID: 23074256 DOI: 10.1073/pnas.1210107109] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
There is an unmet need for circulating biomarkers that can detect early-stage lung cancer. Here we show that a variant form of the nuclear matrix-associated DNA replication factor Ciz1 is present in 34/35 lung tumors but not in adjacent tissue, giving rise to stable protein quantifiable by Western blot in less than a microliter of plasma from lung cancer patients. In two independent sets, with 170 and 160 samples, respectively, variant Ciz1 correctly identified patients who had stage 1 lung cancer with clinically useful accuracy. For set 1, mean variant Ciz1 level in individuals without diagnosed tumors established a threshold that correctly classified 98% of small cell lung cancers (SCLC) and non-SCLC patients [receiver operator characteristic area under the curve (AUC) 0.958]. Within set 2, comparison of patients with stage 1 non-SCLC with asymptomatic age-matched smokers or individuals with benign lung nodules correctly classified 95% of patients (AUCs 0.913 and 0.905), with overall specificity of 76% and 71%, respectively. Moreover, using the mean of controls in set 1, we achieved 95% sensitivity among patients with stage 1 non-SCLC patients in set 2 with 74% specificity, demonstrating the robustness of the classification. RNAi-mediated selective depletion of variant Ciz1 is sufficient to restrain the growth of tumor cells that express it, identifying variant Ciz1 as a functionally relevant driver of cell proliferation in vitro and in vivo. The data show that variant Ciz1 is a strong candidate for a cancer-specific single marker capable of identifying early-stage lung cancer within at-risk groups without resort to invasive procedures.
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15
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Greaves EA, Copeland NA, Coverley D, Ainscough JFX. Cancer associated variant expression and interaction of CIZ1 with cyclin A1 in differentiating male germ cells. J Cell Sci 2012; 125:2466-77. [DOI: 10.1242/jcs.101097] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
CIZ1 is a nuclear matrix associated DNA replication factor unique to higher eukaryotes, for which alternatively spliced isoforms have been associated with a range of disorders. In vitro the CIZ1 N-terminus interacts with cyclins E and A via distinct sites, enabling functional cooperation with cyclin A-Cdk2 to promote replication initiation. C-terminal sequences anchor CIZ1 to fixed sites on the nuclear matrix imposing spatial constraint on cyclin dependent kinase activity. Here we demonstrate that CIZ1 is predominantly expressed as predicted full-length product throughout mouse development, consistent with a ubiquitous role in cell and tissue renewal. CIZ1 is expressed in proliferating stem cells of the testis, but is notably down-regulated following commitment to differentiation. Significantly, CIZ1 is re-expressed at high levels in non-proliferative spermatocytes prior to meiotic division. Sequence analysis identifies at least seven alternatively spliced variants at this time, including a dominant cancer-associated form and a set of novel isoforms. Furthermore, we show that in these post-replicative cells CIZ1 interacts with the germ cell specific cyclin, A1, that has been implicated in DNA double-strand break repair. Consistent with this role, antibody depletion of CIZ1 reduces the capacity for testis extract to repair digested plasmid DNA in vitro. Together, the data imply novel post-replicative roles for CIZ1 in germ cell differentiation that may include meiotic recombination, a process intrinsic to genome stability and diversification.
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