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Liu JCY, Ackermann L, Hoffmann S, Gál Z, Hendriks IA, Jain C, Morlot L, Tatham MH, McLelland GL, Hay RT, Nielsen ML, Brummelkamp T, Haahr P, Mailand N. Concerted SUMO-targeted ubiquitin ligase activities of TOPORS and RNF4 are essential for stress management and cell proliferation. Nat Struct Mol Biol 2024:10.1038/s41594-024-01294-7. [PMID: 38649616 DOI: 10.1038/s41594-024-01294-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Accepted: 03/26/2024] [Indexed: 04/25/2024]
Abstract
Protein SUMOylation provides a principal driving force for cellular stress responses, including DNA-protein crosslink (DPC) repair and arsenic-induced PML body degradation. In this study, using genome-scale screens, we identified the human E3 ligase TOPORS as a key effector of SUMO-dependent DPC resolution. We demonstrate that TOPORS promotes DPC repair by functioning as a SUMO-targeted ubiquitin ligase (STUbL), combining ubiquitin ligase activity through its RING domain with poly-SUMO binding via SUMO-interacting motifs, analogous to the STUbL RNF4. Mechanistically, TOPORS is a SUMO1-selective STUbL that complements RNF4 in generating complex ubiquitin landscapes on SUMOylated targets, including DPCs and PML, stimulating efficient p97/VCP unfoldase recruitment and proteasomal degradation. Combined loss of TOPORS and RNF4 is synthetic lethal even in unstressed cells, involving defective clearance of SUMOylated proteins from chromatin accompanied by cell cycle arrest and apoptosis. Our findings establish TOPORS as a STUbL whose parallel action with RNF4 defines a general mechanistic principle in crucial cellular processes governed by direct SUMO-ubiquitin crosstalk.
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Affiliation(s)
- Julio C Y Liu
- Protein Signaling Program, Novo Nordisk Foundation Center for Protein Research, University of Copenhagen, Copenhagen, Denmark
| | - Leena Ackermann
- Protein Signaling Program, Novo Nordisk Foundation Center for Protein Research, University of Copenhagen, Copenhagen, Denmark
| | - Saskia Hoffmann
- Protein Signaling Program, Novo Nordisk Foundation Center for Protein Research, University of Copenhagen, Copenhagen, Denmark
| | - Zita Gál
- Protein Signaling Program, Novo Nordisk Foundation Center for Protein Research, University of Copenhagen, Copenhagen, Denmark
| | - Ivo A Hendriks
- Proteomics Program, Novo Nordisk Foundation Center for Protein Research, University of Copenhagen, Copenhagen, Denmark
| | - Charu Jain
- Protein Signaling Program, Novo Nordisk Foundation Center for Protein Research, University of Copenhagen, Copenhagen, Denmark
| | - Louise Morlot
- Protein Signaling Program, Novo Nordisk Foundation Center for Protein Research, University of Copenhagen, Copenhagen, Denmark
| | - Michael H Tatham
- Centre for Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dundee, UK
| | - Gian-Luca McLelland
- Division of Biochemistry, The Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - Ronald T Hay
- Centre for Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dundee, UK
| | - Michael Lund Nielsen
- Proteomics Program, Novo Nordisk Foundation Center for Protein Research, University of Copenhagen, Copenhagen, Denmark
| | - Thijn Brummelkamp
- Division of Biochemistry, The Netherlands Cancer Institute, Amsterdam, The Netherlands
- Oncode Institute, Utrecht, The Netherlands
| | - Peter Haahr
- Division of Biochemistry, The Netherlands Cancer Institute, Amsterdam, The Netherlands.
- Department of Cellular and Molecular Medicine, Center for Gene Expression, University of Copenhagen, Copenhagen, Denmark.
| | - Niels Mailand
- Protein Signaling Program, Novo Nordisk Foundation Center for Protein Research, University of Copenhagen, Copenhagen, Denmark.
- Department of Cellular and Molecular Medicine, Center for Chromosome Stability, University of Copenhagen, Copenhagen, Denmark.
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2
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Zhang Z, Huang Y, Xu N, Wang J, Yao T, Xu Y, Qiao D, Gao J, Shen S, Ma J. PLK1 Mitigates Intervertebral Disc Degeneration by Delaying Senescence of Nucleus Pulposus Cells. Front Cell Dev Biol 2022; 10:819262. [PMID: 35372354 PMCID: PMC8964438 DOI: 10.3389/fcell.2022.819262] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2021] [Accepted: 02/11/2022] [Indexed: 01/07/2023] Open
Abstract
Intervertebral disc degeneration (IVDD) is the primary cause of low back pain; however, the molecular mechanisms involved in the pathogenesis of IVDD are not fully understood. Polo-like kinase 1 (PLK1) plays numerous roles in the cell cycle, including in cell proliferation and senescence. To investigate the involvement of PLK1 in IVDD, we used patient tissues and an animal model of IVDD. Samples were analyzed via immunoblotting, quantitative real-time polymerase chain reaction (qPCR), immunofluorescence, and immunohistochemistry. Our results demonstrated that PLK1 expression was decreased in nucleus pulposus cells (NPCs) of degenerative IVDs. The inhibition of PLK1 kinase activity in normal NPCs increased the expression of p53 protein, inhibited cell proliferation, and induced senescence. Our results suggest that PLK1 regulates the degeneration of the IVD through p53, revealing the function and mechanism of PLK1 in IVDD and providing a theoretical basis and experimental evidence for the potential treatment of low back pain.
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Affiliation(s)
- Zhenlei Zhang
- Department of Orthopaedic Surgery, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China.,Key Laboratory of Musculoskeletal System Degeneration and Regeneration Translational Research of Zhejiang University Zhejiang Province, Hangzhou, China
| | - Yizhen Huang
- Department of Orthopaedic Surgery, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China.,Key Laboratory of Musculoskeletal System Degeneration and Regeneration Translational Research of Zhejiang University Zhejiang Province, Hangzhou, China
| | - Nizhen Xu
- Department of Head and Neck Surgery, Institute of Micro-Invasive Surgery of Zhejiang University, Sir Run Run Shaw Hospital, Medical School, Hangzhou, China
| | - Jianle Wang
- Department of Orthopaedic Surgery, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China.,Key Laboratory of Musculoskeletal System Degeneration and Regeneration Translational Research of Zhejiang University Zhejiang Province, Hangzhou, China
| | - Teng Yao
- Department of Orthopaedic Surgery, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China.,Key Laboratory of Musculoskeletal System Degeneration and Regeneration Translational Research of Zhejiang University Zhejiang Province, Hangzhou, China
| | - Yining Xu
- Key Laboratory of Musculoskeletal System Degeneration and Regeneration Translational Research of Zhejiang University Zhejiang Province, Hangzhou, China.,Shaoxing University School of Medicine, Shaoxing, China
| | - Di Qiao
- Key Laboratory of Musculoskeletal System Degeneration and Regeneration Translational Research of Zhejiang University Zhejiang Province, Hangzhou, China.,Shaoxing University School of Medicine, Shaoxing, China
| | - Jun Gao
- Department of Orthopaedic Surgery, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China.,Key Laboratory of Musculoskeletal System Degeneration and Regeneration Translational Research of Zhejiang University Zhejiang Province, Hangzhou, China
| | - Shuying Shen
- Department of Orthopaedic Surgery, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China.,Key Laboratory of Musculoskeletal System Degeneration and Regeneration Translational Research of Zhejiang University Zhejiang Province, Hangzhou, China
| | - Jianjun Ma
- Department of Orthopaedic Surgery, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, China.,Key Laboratory of Musculoskeletal System Degeneration and Regeneration Translational Research of Zhejiang University Zhejiang Province, Hangzhou, China.,Shaoxing University School of Medicine, Shaoxing, China
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3
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Hariharasudhan G, Jeong SY, Kim MJ, Jung SM, Seo G, Moon JR, Lee S, Chang IY, Kee Y, You H, Lee JH. OUP accepted manuscript. Nucleic Acids Res 2022; 50:1501-1516. [PMID: 35061896 PMCID: PMC8860612 DOI: 10.1093/nar/gkac009] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Revised: 12/23/2021] [Accepted: 01/13/2022] [Indexed: 11/24/2022] Open
Abstract
Homologous recombination (HR) is critical for error-free repair of DNA double-strand breaks. Chromatin loading of RAD51, a key protein that mediates the recombination, is a crucial step in the execution of the HR repair. Here, we present evidence that SUMOylation of RAD51 is crucial for the RAD51 recruitment to chromatin and HR repair. We found that topoisomerase 1-binding arginine/serine-rich protein (TOPORS) induces the SUMOylation of RAD51 at lysine residues 57 and 70 in response to DNA damaging agents. The SUMOylation was facilitated by an ATM-induced phosphorylation of TOPORS at threonine 515 upon DNA damage. Knockdown of TOPORS or expression of SUMOylation-deficient RAD51 mutants caused reduction in supporting normal RAD51 functions during the HR repair, suggesting the physiological importance of the modification. We found that the SUMOylation-deficient RAD51 reduces the association with its crucial binding partner BRCA2, explaining its deficiency in supporting the HR repair. These findings altogether demonstrate a crucial role for TOPORS-mediated RAD51 SUMOylation in promoting HR repair and genomic maintenance.
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Affiliation(s)
- Gurusamy Hariharasudhan
- Laboratory of Genomic Instability and Cancer Therapeutics, Chosun University School of Medicine, 309 Pilmun-daero, Dong-gu, Gwangju 61452, Republic of Korea
- Department of Cellular and Molecular Medicine, Chosun University School of Medicine, 309 Pilmun-daero, Dong-gu, Gwangju 61452, Republic of Korea
| | - Seo-Yeon Jeong
- Laboratory of Genomic Instability and Cancer Therapeutics, Chosun University School of Medicine, 309 Pilmun-daero, Dong-gu, Gwangju 61452, Republic of Korea
- Department of Pharmacology, Chosun University School of Medicine, 309 Pilmun-daero, Dong-gu, Gwangju 61452, Republic of Korea
| | - Min-Ji Kim
- Laboratory of Genomic Instability and Cancer Therapeutics, Chosun University School of Medicine, 309 Pilmun-daero, Dong-gu, Gwangju 61452, Republic of Korea
- Department of Cellular and Molecular Medicine, Chosun University School of Medicine, 309 Pilmun-daero, Dong-gu, Gwangju 61452, Republic of Korea
| | - Sung Mi Jung
- Laboratory of Genomic Instability and Cancer Therapeutics, Chosun University School of Medicine, 309 Pilmun-daero, Dong-gu, Gwangju 61452, Republic of Korea
- Department of Cellular and Molecular Medicine, Chosun University School of Medicine, 309 Pilmun-daero, Dong-gu, Gwangju 61452, Republic of Korea
| | - Gwanwoo Seo
- Laboratory of Genomic Instability and Cancer Therapeutics, Chosun University School of Medicine, 309 Pilmun-daero, Dong-gu, Gwangju 61452, Republic of Korea
- Department of Pharmacology, Chosun University School of Medicine, 309 Pilmun-daero, Dong-gu, Gwangju 61452, Republic of Korea
| | - Ju-Ran Moon
- Laboratory of Genomic Instability and Cancer Therapeutics, Chosun University School of Medicine, 309 Pilmun-daero, Dong-gu, Gwangju 61452, Republic of Korea
- Department of Cellular and Molecular Medicine, Chosun University School of Medicine, 309 Pilmun-daero, Dong-gu, Gwangju 61452, Republic of Korea
| | - Sumi Lee
- Laboratory of Genomic Instability and Cancer Therapeutics, Chosun University School of Medicine, 309 Pilmun-daero, Dong-gu, Gwangju 61452, Republic of Korea
- Department of Cellular and Molecular Medicine, Chosun University School of Medicine, 309 Pilmun-daero, Dong-gu, Gwangju 61452, Republic of Korea
| | - In-Youb Chang
- Department of Anatomy, Chosun University School of Medicine, 309 Pilmun-daero, Dong-gu, Gwangju 61452, Republic of Korea
| | - Younghoon Kee
- Correspondence may also be addressed to Younghoon Kee. Tel: +82 53 785 1610;
| | - Ho Jin You
- Correspondence may also be addressed to Ho Jin You. Tel: +82 62 230 6337;
| | - Jung-Hee Lee
- To whom correspondence should be addressed. Tel: +82 62 230 6399;
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4
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Strong A, Simone L, Krentz A, Vaccaro C, Watson D, Ron H, Kalish JM, Pedro HF, Zackai EH, Hakonarson H. Expanding the genetic landscape of oral-facial-digital syndrome with two novel genes. Am J Med Genet A 2021; 185:2409-2416. [PMID: 34132027 PMCID: PMC8361718 DOI: 10.1002/ajmg.a.62337] [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: 04/24/2021] [Revised: 04/28/2021] [Accepted: 04/30/2021] [Indexed: 12/18/2022]
Abstract
Oral‐facial‐digital syndromes (OFDS) are a heterogeneous and rare group of Mendelian disorders characterized by developmental abnormalities of the oral cavity, face, and digits caused by dysfunction of the primary cilium, a mechanosensory organelle that exists atop most cell types that facilitates organ patterning and growth. OFDS is inherited both in an X‐linked dominant, X‐linked recessive, and autosomal recessive manner. Importantly, though many of the causal genes for OFDS have been identified, up to 40% of OFD syndromes are of unknown genetic basis. Here we describe three children with classical presentations of OFDS including lingual hamartomas, polydactyly, and characteristic facial features found by exome sequencing to harbor variants in causal genes not previously associated with OFDS. We describe a female with hypothalamic hamartoma, urogenital sinus, polysyndactyly, and multiple lingual hamartomas consistent with OFDVI with biallelic pathogenic variants in CEP164, a gene associated with ciliopathy‐spectrum disease, but never before with OFDS. We additionally describe two unrelated probands with postaxial polydactyly, multiple lingual hamartomas, and dysmorphic features both found to be homozygous for an identical TOPORS missense variant, c.29 C>A; (p.Pro10Gln). Heterozygous TOPORS pathogenic gene variants are associated with autosomal dominant retinitis pigmentosa, but never before with syndromic ciliopathy. Of note, both probands are of Dominican ancestry, suggesting a possible founder allele.
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Affiliation(s)
- Alanna Strong
- Division of Human Genetics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA.,The Center for Applied Genomics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Laurie Simone
- Center for Genetic and Genomic Medicine, Hackensack University Medical Center, Hackensack, New Jersey, USA
| | | | - Courtney Vaccaro
- The Center for Applied Genomics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Deborah Watson
- The Center for Applied Genomics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Hayley Ron
- Division of Human Genetics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Jennifer M Kalish
- Division of Human Genetics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA.,Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Helio F Pedro
- Center for Genetic and Genomic Medicine, Hackensack University Medical Center, Hackensack, New Jersey, USA
| | - Elaine H Zackai
- Division of Human Genetics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA.,Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Hakon Hakonarson
- Division of Human Genetics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA.,The Center for Applied Genomics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA.,Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.,Division of Pulmonary Medicine, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
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5
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Regulating tumor suppressor genes: post-translational modifications. Signal Transduct Target Ther 2020; 5:90. [PMID: 32532965 PMCID: PMC7293209 DOI: 10.1038/s41392-020-0196-9] [Citation(s) in RCA: 179] [Impact Index Per Article: 44.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Revised: 05/19/2020] [Accepted: 05/24/2020] [Indexed: 01/10/2023] Open
Abstract
Tumor suppressor genes cooperate with each other in tumors. Three important tumor suppressor proteins, retinoblastoma (Rb), p53, phosphatase, and tensin homolog deleted on chromosome ten (PTEN) are functionally associated and they regulated by post-translational modification (PTMs) as well. PTMs include phosphorylation, SUMOylation, acetylation, and other novel modifications becoming growing appreciated. Because most of PTMs are reversible, normal cells use them as a switch to control the state of cells being the resting or proliferating, and PTMs also involve in cell survival and cell cycle, which may lead to abnormal proliferation and tumorigenesis. Although a lot of studies focus on the importance of each kind of PTM, further discoveries shows that tumor suppressor genes (TSGs) form a complex “network” by the interaction of modification. Recently, there are several promising strategies for TSGs for they change more frequently than carcinogenic genes in cancers. We here review the necessity, characteristics, and mechanisms of each kind of post-translational modification on Rb, p53, PTEN, and its influence on the precise and selective function. We also discuss the current antitumoral therapies of Rb, p53 and PTEN as predictive, prognostic, and therapeutic target in cancer.
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6
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TOPORS, a tumor suppressor protein, contributes to the maintenance of higher-order chromatin architecture. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2020; 1863:194518. [PMID: 32113985 DOI: 10.1016/j.bbagrm.2020.194518] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2019] [Revised: 02/06/2020] [Accepted: 02/22/2020] [Indexed: 11/22/2022]
Abstract
In the nucleus, chromosomes are hierarchically folded into active (A) and inactive (B) compartments composed of topologically associating domains (TADs). Genomic regions interact with nuclear lamina, termed lamina-associated domains (LADs). However, the molecular mechanisms underlying these 3D chromatin architectures remain incompletely understood. Here, we investigated the role of a potential tumor suppressor, TOP1 Binding Arginine/Serine Rich Protein (TOPORS), in genome organization. In mouse hepatocytes, chromatin interactions between A and B compartments increase and compartmentalization strength is reduced significantly upon Topors knockdown. Correspondingly, strength of TAD boundaries located at A/B borders is weakened. In the absence of TOPORS, chromatin-lamina interactions decrease and the coverage of LADs reduces from 53.31% to 46.52%. Interestingly, these changes in 3D genome are associated with PML nuclear bodies and PML-associated domains (PADs). Moreover, chromatin accessibility is altered predominantly at intergenic regions upon Topors knockdown, including a subset of enhancers. These alterations of chromatin are concordant with transcriptome changes, which are associated with carcinogenesis. Collectively, our findings demonstrate that TOPORS functions as a regulator in chromatin structure, providing novel insight into the architectural roles of tumor suppressors in higher-order genome organization.
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7
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Graham AM, Lavretsky P, Muñoz-Fuentes V, Green AJ, Wilson RE, McCracken KG. Migration-Selection Balance Drives Genetic Differentiation in Genes Associated with High-Altitude Function in the Speckled Teal (Anas flavirostris) in the Andes. Genome Biol Evol 2018; 10:14-32. [PMID: 29211852 PMCID: PMC5757641 DOI: 10.1093/gbe/evx253] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/30/2017] [Indexed: 12/30/2022] Open
Abstract
Local adaptation frequently occurs across populations as a result of migration-selection balance between divergent selective pressures and gene flow associated with life in heterogeneous landscapes. Studying the effects of selection and gene flow on the adaptation process can be achieved in systems that have recently colonized extreme environments. This study utilizes an endemic South American duck species, the speckled teal (Anas flavirostris), which has both high- and low-altitude populations. High-altitude speckled teal (A. f. oxyptera) are locally adapted to the Andean environment and mostly allopatric from low-altitude birds (A. f. flavirostris); however, there is occasional gene flow across altitudinal gradients. In this study, we used next-generation sequencing to explore genetic patterns associated with high-altitude adaptation in speckled teal populations, as well as the extent to which the balance between selection and migration have affected genetic architecture. We identified a set of loci with allele frequencies strongly correlated with altitude, including those involved in the insulin-like signaling pathway, bone morphogenesis, oxidative phosphorylation, responders to hypoxia-induced DNA damage, and feedback loops to the hypoxia-inducible factor pathway. These same outlier loci were found to have depressed gene flow estimates, as well as being highly concentrated on the Z-chromosome. Our results suggest a multifactorial response to life at high altitudes through an array of interconnected pathways that are likely under positive selection and whose genetic components seem to be providing an effective genomic barrier to interbreeding, potentially functioning as an avenue for population divergence and speciation.
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Affiliation(s)
| | | | - Violeta Muñoz-Fuentes
- European Molecular Biology Laboratory, European Bioinformatics Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, United Kingdom
- Estación Biológica de Doñana, EBD-CSIC, Sevilla, Spain
| | - Andy J Green
- Estación Biológica de Doñana, EBD-CSIC, Sevilla, Spain
| | - Robert E Wilson
- Institute of Arctic Biology and University of Alaska Museum, University of Alaska, Fairbanks
| | - Kevin G McCracken
- Department of Biology, University of Miami
- Institute of Arctic Biology and University of Alaska Museum, University of Alaska, Fairbanks
- Rosenstiel School of Marine and Atmospheric Sciences, University of Miami
- John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine
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8
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Kumar S, Sharma G, Chakraborty C, Sharma AR, Kim J. Regulatory functional territory of PLK-1 and their substrates beyond mitosis. Oncotarget 2017; 8:37942-37962. [PMID: 28415805 PMCID: PMC5514964 DOI: 10.18632/oncotarget.16290] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Accepted: 03/03/2017] [Indexed: 12/04/2022] Open
Abstract
Polo-like kinase 1 (PLK-1) is a well-known (Ser/Thr) mitotic protein kinase and is considered as a proto-oncogene. As hyper-activation of PLK-1 is broadly associated with poor prognosis and cancer progression, it is one of the most extensively studied mitotic kinases. During mitosis, PLK-1 regulates various cell cycle events, such as spindle pole maturation, chromosome segregation and cytokinesis. However, studies have demonstrated that the role of PLK-1 is not only restricted to mitosis, but PLK-1 can also regulate other vital events beyond mitosis, including transcription, translation, ciliogenesis, checkpoint adaptation and recovery, apoptosis, chromosomes dynamics etc. Recent reviews have tried to define the regulatory role of PLK-1 during mitosis progression and tumorigenesis, but its' functional role beyond mitosis is still largely unexplored. PLK-1 can regulate the activity of many proteins that work outside of its conventional territory. The dysregulation of these proteins can cause diseases such as Alzheimer's disease, tumorigenesis etc. and may also lead to drug resistance. Thus, in this review, we discussed the versatile role of PLK-1 and tried to collect data to validate its' functional role in cell cycle regulation apart from mitosis.
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Affiliation(s)
- Shiv Kumar
- Department of Biochemistry, Institute of Cell Differentiation and Aging, Hallym University, College of Medicine, Chucheonsi, Gangwondo, Republic of Korea
| | - Garima Sharma
- Institute For Skeletal Aging & Orthopedic Surgery, Hallym University, College of Medicine, Chucheonsi, Gangwondo, Republic of Korea
| | - Chiranjib Chakraborty
- Department of Bio-informatics, School of Computer and Information Sciences, Galgotias University, Greater Noida, Uttar Pradesh, India
| | - Ashish Ranjan Sharma
- Institute For Skeletal Aging & Orthopedic Surgery, Hallym University, College of Medicine, Chucheonsi, Gangwondo, Republic of Korea
| | - Jaebong Kim
- Department of Biochemistry, Institute of Cell Differentiation and Aging, Hallym University, College of Medicine, Chucheonsi, Gangwondo, Republic of Korea
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TOPORS, a Dual E3 Ubiquitin and Sumo1 Ligase, Interacts with 26 S Protease Regulatory Subunit 4, Encoded by the PSMC1 Gene. PLoS One 2016; 11:e0148678. [PMID: 26872363 PMCID: PMC4752349 DOI: 10.1371/journal.pone.0148678] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2015] [Accepted: 01/20/2016] [Indexed: 11/19/2022] Open
Abstract
The significance of the ubiquitin-proteasome system (UPS) for protein degradation has been highlighted in the context of neurodegenerative diseases, including retinal dystrophies. TOPORS, a dual E3 ubiquitin and SUMO1 ligase, forms a component of the UPS and selected substrates for its enzymatic activities, such as DJ-1/PARK7 and APOBEC2, are important for neuronal as well as retinal homeostasis, respectively. TOPORS is ubiquitously expressed, yet its mutations are only known to result in autosomal dominant retinitis pigmentosa. We performed a yeast two-hybrid (Y2H) screen of a human retinal cDNA library in order to identify interacting protein partners of TOPORS from the retina, and thus begin delineating the putative disease mechanism(s) associated with the retina-specific phenotype resulting from mutations in TOPORS. The screen led to isolation of the 26 S protease regulatory subunit 4 (P26s4/ PSMC1), an ATPase indispensable for correct functioning of UPS-mediated proteostasis. The interaction between endogenous TOPORS and P26s4 proteins was validated by co-immuno-precipitation from mammalian cell extracts and further characterised by immunofluorescent co-localisation studies in cell lines and retinal sections. Findings from hTERT-RPE1 and 661W cells demonstrated that TOPORS and P26s4 co-localise at the centrosome in cultured cells. Immunofluorescent staining of mouse retinae revealed a strong P26s4 reactivity at the interface between retinal pigmented epithelium (RPE) layer and the photoreceptors outer segments (OS). This finding leads us to speculate that P26s4, along with TOPORS, may have a role(s) in RPE phagocytosis, in addition to contributing to the overall photoreceptor and retinal homeostasis via the UPS.
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10
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Seong KM, Nam SY, Kim JY, Yang KH, An S, Jin YW, Kim CS. TOPORS modulates H2AX discriminating genotoxic stresses. J Biochem Mol Toxicol 2012; 26:429-38. [PMID: 22972498 DOI: 10.1002/jbt.21438] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2012] [Revised: 07/26/2012] [Accepted: 08/11/2012] [Indexed: 11/07/2022]
Abstract
H2AX plays an important role in chromatin reorganization implicated in DNA repair and apoptosis under various DNA damaging conditions. In this study, the interaction between TOPORS (topoisomerase I-binding protein) and H2AX was verified using mammalian cell extracts exposed to diverse DNA damaging stresses such as ionizing radiation, doxorubicin, camptothecin, and hydrogen peroxide. In vitro assays for ubiquitination revealed that TOPORS functions as a novel E3 ligase for H2AX ubiquitination. TOPORS was found to be dissociated from H2AX proteins when cells were exposed to oxidative stress, but not replication-inducing DNA damaging stress. The protein stability of H2AX was decreased when TOPORS was ectopically expressed in cells, and oxidative stresses such as hydrogen peroxide and ionizing radiation induced recovery of the H2AX protein level. Therefore, these biochemical data suggest that TOPORS plays a key role in the turnover of H2AX protein, discriminating the type of DNA damaging stress.
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Affiliation(s)
- Ki Moon Seong
- Division of Radiation Effect Research, Radiation Health Research Institute, Korea Hydro & Nuclear Power Co., Ltd., 132-703, Seoul, Korea.
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11
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Braun KR, DeWispelaere AM, Bressler SL, Fukai N, Kenagy RD, Chen L, Clowes AW, Kinsella MG. Inhibition of PDGF-B induction and cell growth by syndecan-1 involves the ubiquitin and SUMO-1 ligase, Topors. PLoS One 2012; 7:e43701. [PMID: 22912899 PMCID: PMC3422340 DOI: 10.1371/journal.pone.0043701] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2012] [Accepted: 07/23/2012] [Indexed: 01/14/2023] Open
Abstract
Syndecans are receptors for soluble ligands, including heparin-binding growth factors, and matrix proteins. However, intracellular targets of syndecan-1 (Sdc-1)-mediated signaling are not fully understood. A yeast two-hybrid protein interaction screening of a mouse embryo library identified the ubiquitin and SUMO-1 E3 ligase, Topors, as a novel ligand of the Sdc-1 cytoplasmic domain (S1CD), a finding confirmed by ligand blotting and co-precipitation with Sdc-1 from cell lysates. Deletion mutagenesis identified an 18-amino acid sequence of Topors required for the interaction with the S1CD. By immunohistochemistry, Topors and Sdc-1 co-localized near the cell periphery in normal murine mammary gland (NMuMG) cells in vitro and in mouse embryonic epithelia in vivo. Finally, siRNA-mediated knockdown of Topors demonstrated that Topors is a growth promoter for murine arterial smooth muscle cells and is required for the inhibitory effect of Sdc-1 on cell growth and platelet-derived growth factor-B induction. These data suggest a novel mechanism for the inhibitory effects of Sdc-1 on cell growth that involves the interaction between the cytoplasmic domain of Sdc-1 and the SUMO-1 E3 ligase, Topors.
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Affiliation(s)
- Kathleen R. Braun
- Benaroya Research Institute at Virginia Mason, Seattle, Washington, United States of America
| | - Allison M. DeWispelaere
- Benaroya Research Institute at Virginia Mason, Seattle, Washington, United States of America
| | - Steven L. Bressler
- Benaroya Research Institute at Virginia Mason, Seattle, Washington, United States of America
| | - Nozomi Fukai
- Department of Surgery, University of Washington, Seattle, Washington, United States of America
| | - Richard D. Kenagy
- Department of Surgery, University of Washington, Seattle, Washington, United States of America
| | - Lihua Chen
- Department of Surgery, University of Washington, Seattle, Washington, United States of America
| | - Alexander W. Clowes
- Department of Surgery, University of Washington, Seattle, Washington, United States of America
| | - Michael G. Kinsella
- Benaroya Research Institute at Virginia Mason, Seattle, Washington, United States of America
- * E-mail:
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12
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Lee SW, Seong MW, Jeon YJ, Chung CH. Ubiquitin E3 ligases controlling p53 stability. Anim Cells Syst (Seoul) 2012. [DOI: 10.1080/19768354.2012.688769] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022] Open
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13
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Nuclear structure and chromosome segregation in Drosophila male meiosis depend on the ubiquitin ligase dTopors. Genetics 2011; 189:779-93. [PMID: 21900273 DOI: 10.1534/genetics.111.133819] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In many organisms, homolog pairing and synapsis at meiotic prophase depend on interactions between chromosomes and the nuclear membrane. Male Drosophila lack synapsis, but nonetheless, their chromosomes closely associate with the nuclear periphery at prophase I. To explore the functional significance of this association, we characterize mutations in nuclear blebber (nbl), a gene required for both spermatocyte nuclear shape and meiotic chromosome transmission. We demonstrate that nbl corresponds to dtopors, the Drosophila homolog of the mammalian dual ubiquitin/small ubiquitin-related modifier (SUMO) ligase Topors. We show that mutations in dtopors cause abnormalities in lamin localizations, centriole separation, and prophase I chromatin condensation and also cause anaphase I bridges that likely result from unresolved homolog connections. Bridge formation does not require mod(mdg4) in meiosis, suggesting that bridges do not result from misregulation of the male homolog conjunction complex. At the ultrastructural level, we observe disruption of nuclear shape, an uneven perinuclear space, and excess membranous structures. We show that dTopors localizes to the nuclear lamina at prophase, and also transiently to intranuclear foci. As a role of dtopors at gypsy insulator has been reported, we also asked whether these new alleles affected expression of the gypsy-induced mutation ct(6) and found that it was unaltered in dtopors homozygotes. Our results indicate that dTopors is required for germline nuclear structure and meiotic chromosome segregation, but in contrast, is not necessary for gypsy insulator function. We suggest that dtopors plays a structural role in spermatocyte lamina that is critical for multiple aspects of meiotic chromosome transmission.
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14
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Chakarova CF, Khanna H, Shah AZ, Patil SB, Sedmak T, Murga-Zamalloa CA, Papaioannou MG, Nagel-Wolfrum K, Lopez I, Munro P, Cheetham M, Koenekoop RK, Rios RM, Matter K, Wolfrum U, Swaroop A, Bhattacharya SS. TOPORS, implicated in retinal degeneration, is a cilia-centrosomal protein. Hum Mol Genet 2010; 20:975-87. [PMID: 21159800 DOI: 10.1093/hmg/ddq543] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
We recently reported that mutations in the widely expressed nuclear protein TOPORS (topoisomerase I-binding arginine/serine rich) are associated with autosomal dominant retinal degeneration. However, the precise localization and a functional role of TOPORS in the retina remain unknown. Here, we demonstrate that TOPORS is a novel component of the photoreceptor sensory cilium, which is a modified primary cilium involved with polarized trafficking of proteins. In photoreceptors, TOPORS localizes primarily to the basal bodies of connecting cilium and in the centrosomes of cultured cells. Morpholino-mediated silencing of topors in zebrafish embryos demonstrates in another species a comparable retinal problem as seen in humans, resulting in defective retinal development and failure to form outer segments. These defects can be rescued by mRNA encoding human TOPORS. Taken together, our data suggest that TOPORS may play a key role in regulating primary cilia-dependent photoreceptor development and function. Additionally, it is well known that mutations in other ciliary proteins cause retinal degeneration, which may explain why mutations in TOPORS result in the same phenotype.
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15
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Liu XS, Song B, Liu X. The substrates of Plk1, beyond the functions in mitosis. Protein Cell 2010; 1:999-1010. [PMID: 21153517 PMCID: PMC4875153 DOI: 10.1007/s13238-010-0131-x] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2010] [Accepted: 11/08/2010] [Indexed: 12/01/2022] Open
Abstract
Polo-like kinase 1 (Plk1) is a key regulator of cell division in eukaryotic cells. In this short review, we briefly summarized the well-established functions modulated by Plk1 during mitosis. Beyond mitosis, we focused mainly on the unexpected processes in which Plk1 emerges as a critical player, including microtubule dynamics, DNA replication, chromosome dynamics, p53 regulation, and recovery from the G2 DNA-damage checkpoint. Our discussion is mainly based on the critical substrates targeted by Plk1 during these cellular events and the functional significance associated with each phosphorylation event.
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Affiliation(s)
- X. Shawn Liu
- Department of Biochemistry, Purdue University, West Lafayette, Indiana 47907 USA
| | - Bing Song
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907 USA
| | - Xiaoqi Liu
- Department of Biochemistry, Purdue University, West Lafayette, Indiana 47907 USA
- Center for Cancer Research, Purdue University, West Lafayette, Indiana 47907 USA
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16
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Yang X, Li H, Deng A, Liu X. Plk1 phosphorylation of Topors is involved in its degradation. Mol Biol Rep 2010; 37:3023-8. [PMID: 19821153 PMCID: PMC4965875 DOI: 10.1007/s11033-009-9871-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2009] [Accepted: 09/29/2009] [Indexed: 10/20/2022]
Abstract
Topors is a DNA topoisomerase I- and p53-binding protein, and mainly functions as a p53 regulator. Accumulating evidence also supports the notion that Topors plays the role as a negative regulator of cell growth, and possibly as a tumor suppressor. Here, we demonstrated that Topors is also involved in normal mitotic progression, since Topors depletion delays mitotic entry and affects mitotic progression. Furthermore, Topors is degradated in response to the activation of the spindle checkpoint. Significantly, Polo-like kinase 1 (Plk1)-associated phosphorylation of Topors at S718 is essential for nocodazole-induced degradation of Topors.
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Affiliation(s)
- Xiaoming Yang
- College of Chemistry, Sichuan University, Chengdu 610064, China.
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17
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Selmer KK, Grøndahl J, Riise R, Brandal K, Braaten Ø, Bragadottir R, Undlien DE. Autosomal dominant pericentral retinal dystrophy caused by a novel missense mutation in the TOPORS gene. Acta Ophthalmol 2010; 88:323-8. [PMID: 19183411 DOI: 10.1111/j.1755-3768.2008.01465.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
PURPOSE This study aimed to identify the genetic cause of autosomal dominant pericentral retinal dystrophy (adPRD) in a large Norwegian family with 35 affected members. METHODS The family was characterized by clinical ophthalmological examination along with fundus photography, dark adaptometry and electroretinography. We performed a genome-wide linkage analysis followed by sequencing of a candidate gene to identify the mutation causing the disease. RESULTS The ophthalmological examinations revealed an atypical form of retinitis pigmentosa (RP), which we prefer to call adPRD. Compared with classical RP, this phenotype has a favourable prognosis. Linkage analysis showed a linkage peak covering the most recently reported adRP gene TOPORS. This gene was sequenced in 19 family members and a novel missense mutation, c.1205a>c, resulting in an amino acid substitution p.Q402P, was detected in all affected members. The mutation showed complete co-segregation with the disease in this family, with a LOD score of 7.3. It is located in a highly conserved region and alignment with the appropriate DNA sequence from other species shows complete conservation of this amino acid. The mutation was not detected in 207 healthy, unrelated controls of Norwegian origin. CONCLUSIONS We present a novel mutation in the TOPORS gene co-segregating with a distinct phenotype of adPRD in a large Norwegian family.
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18
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Yang Z, Carey JF, Champoux JJ. Mutational analysis of the preferential binding of human topoisomerase I to supercoiled DNA. FEBS J 2009; 276:5906-19. [PMID: 19740104 DOI: 10.1111/j.1742-4658.2009.07270.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Human topoisomerase I binds DNA in a topology-dependent fashion with a strong preference for supercoiled DNAs of either sign over relaxed circular DNA. One hypothesis to account for this preference is that a second DNA-binding site exists on the enzyme that mediates an association with the nodes present in supercoiled DNA. The failure of the enzyme to dimerize, even in the presence of DNA, appears to rule out the hypothesis that two binding sites are generated by dimerization of the protein. A series of mutant protein constructs was generated to test the hypotheses that the homeodomain-like core subdomain II (residues 233-319) provides a second DNA-binding site, or that the linker or basic residues in core subdomain III are involved in the preferential binding to supercoiled DNAs. When putative DNA contact points within core subdomain II were altered or the domain was removed altogether, there was no effect on the ability of the enzyme to recognize supercoiled DNA, as measured by both a gel shift assay and a competition binding assay. However, the preference for supercoils was noticeably reduced for a form of the enzyme lacking the coiled-coil linker region or when pairs of lysines were changed to glutamic acids in core subdomain III. The results obtained implicate the linker and solvent-exposed basic residues in core subdomain III in the preferential binding of human topoisomerase I to supercoiled DNA.
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Affiliation(s)
- Zheng Yang
- Department of Microbiology, School of Medicine, University of Washington, Seattle, WA 98195-7242, USA
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19
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Yang X, Li H, Zhou Z, Wang WH, Deng A, Andrisani O, Liu X. Plk1-mediated phosphorylation of Topors regulates p53 stability. J Biol Chem 2009; 284:18588-92. [PMID: 19473992 PMCID: PMC2707202 DOI: 10.1074/jbc.c109.001560] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2009] [Revised: 05/20/2009] [Indexed: 11/06/2022] Open
Abstract
Polo-like kinase 1 (Plk1) overexpression is associated with tumorigenesis by an unknown mechanism. Likewise, Plk1 was suggested to act as a negative regulator of tumor suppressor p53, but the mechanism remains to be determined. Herein, we have identified topoisomerase I-binding protein (Topors), a p53-binding protein, as a Plk1 target. We show that Plk1 phosphorylates Topors on Ser(718) in vivo. Significantly, expression of a Plk1-unphosphorylatable Topors mutant (S718A) leads to a dramatic accumulation of p53 through inhibition of p53 degradation. Topors is an ubiquitin and small ubiquitin-like modifier ubiquitin-protein isopeptide ligase (SUMO E3) ligase. Plk1-mediated phosphorylation of Topors inhibits Topors-mediated sumoylation of p53, whereas p53 ubiquitination is enhanced, leading to p53 degradation. These results demonstrate that Plk1 modulates Topors activity in suppressing p53 function and identify a likely mechanism for the tumorigenic potential of Plk1.
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Affiliation(s)
- Xiaoming Yang
- From the College of Chemistry, Sichuan University, Chengdu 610064, China and
- the Departments of Biochemistry and
| | | | | | - Wen-Horng Wang
- Basic Medical Sciences, Purdue University, West Lafayette, Indiana 47907
| | - Anping Deng
- From the College of Chemistry, Sichuan University, Chengdu 610064, China and
| | - Ourania Andrisani
- Basic Medical Sciences, Purdue University, West Lafayette, Indiana 47907
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20
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Lee MT, Bachant J. SUMO modification of DNA topoisomerase II: trying to get a CENse of it all. DNA Repair (Amst) 2009; 8:557-68. [PMID: 19230795 DOI: 10.1016/j.dnarep.2009.01.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
DNA topoisomerase II (topo II) is an essential determinant of chromosome structure and function, acting to resolve topological problems inherent in recombining, transcribing, replicating and segregating DNA. In particular, the unique decatenating activity of topo II is required for sister chromatids to disjoin and separate in mitosis. Topo II exhibits a dynamic localization pattern on mitotic chromosomes, accumulating at centromeres and axial chromosome cores prior to anaphase. In organisms ranging from yeast to humans, a fraction of topo II is targeted for SUMO conjugation in mitotic cells, and here we review our current understanding of the significance of this modification. As we shall see, an emerging consensus is that in metazoans SUMO modification is required for topo II to accumulate at centromeres, and that in the absence of this regulation there is an elevated frequency of chromosome non-disjunction, segregation errors, and aneuploidy. The underlying molecular mechanisms for how SUMO controls topo II are as yet unclear. In closing, however, we will evaluate two possible interpretations: one in which SUMO promotes enzyme turnover, and a second in which SUMO acts as a localization tag for topo II chromosome trafficking.
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Affiliation(s)
- Ming-Ta Lee
- Department of Cell Biology and Neuroscience, University of California, Riverside, Riverside, CA 92521, USA
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21
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Park HJ, Zheng H, Kulkarni D, Kerrigan J, Pungaliya P, Saleem A, Rubin EH. Identification of phosphorylation sites of TOPORS and a role for serine 98 in the regulation of ubiquitin but not SUMO E3 ligase activity. Biochemistry 2009; 47:13887-96. [PMID: 19053840 DOI: 10.1021/bi801904q] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
TOPORS is the first example of a protein that possesses both ubiquitin and SUMO E3 ligase activity. The ubiquitination activity maps to a conserved RING domain in the N-terminal region of the protein, which is not required for sumoylation activity. Similar to other E3 ligases, it is likely that the ubiquitin and sumoylation activities of TOPORS are regulated by post-translational modifications. Therefore, we employed mass spectrometry to identify post-translational modifications of TOPORS. Several putative phosphorylated regions were identified in conserved regions of the protein. We investigated the role of phosphorylation of serine 98, which is adjacent to the RING domain, in both cells and in vitro. Mutation of serine 98 to aspartic acid resulted in an increase in the ubiquitin ligase activity of TOPORS both in cells and in vitro. In addition, this mutation increased the binding of TOPORS to the E2 enzyme UbcH5a both in vitro and in cells. Conversely, a phospho-deficient mutant (S98A) exhibited little change in ubiquitin ligase activity compared to wild-type TOPORS, both in cells and in vitro. Neither of the mutants affected the localization of TOPORS to punctate nuclear regions. In addition, neither mutant affected the SUMO ligase activity of TOPORS in cells or in vitro. Molecular modeling studies support a role for serine 98 in regulating TOPORS-E2 interactions. Our findings indicate that phosphorylation of serine 98 regulates the ubiquitin but not the SUMO ligase activity of TOPORS, consistent with a potential binary switch function for TOPORS in protein ubiquitination versus sumoylation.
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Affiliation(s)
- Hye-Jin Park
- Departments of Pharmacology and Medicine, The Cancer Institute of New Jersey, Robert Wood Johnson Medical School, University of Medicine and Dentistry of New Jersey, 195 Little Albany Street, New Brunswick, New Jersey 08901, USA
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22
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Sordet O, Goldman A, Redon C, Solier S, Rao VA, Pommier Y. Topoisomerase I requirement for death receptor-induced apoptotic nuclear fission. J Biol Chem 2008; 283:23200-8. [PMID: 18556653 PMCID: PMC2516995 DOI: 10.1074/jbc.m801146200] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2008] [Revised: 06/12/2008] [Indexed: 12/31/2022] Open
Abstract
Topoisomerase I (Top1) is known to relax DNA supercoiling generated by transcription, replication, and chromatin remodeling. However, it can be trapped on DNA as cleavage complexes (Top1cc) by oxidative and carcinogenic DNA lesions, base damage, and camptothecin treatment. We show here that Top1 is also functionally involved in death receptor-induced programmed cell death. In cells exposed to TRAIL or Fas ligand, Top1cc form at the onset of apoptosis. Those apoptotic Top1cc are prevented by caspase inhibition and Bax inactivation, indicating that both caspases and the mitochondrial death pathway are required for their formation. Accordingly, direct activation of the mitochondrial pathway by BH3 mimetic molecules induces apoptotic Top1cc. We also show that TRAIL-induced apoptotic Top1cc are preferentially formed by caspase-3-cleaved Top1 at sites of oxidative DNA lesions with an average of one apoptotic Top1cc/100 kbp. Examination of Top1 knock-down cells treated with TRAIL revealed similar DNA fragmentation but a marked decrease in apoptotic nuclear fission with reduced formation of nuclear bodies. Thus, we propose that Top1 contributes to the full apoptotic responses induced by TRAIL.
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Affiliation(s)
- Olivier Sordet
- Laboratory of Molecular Pharmacology, Center for Cancer Research, NCI, National Institutes of Health, Bethesda, Maryland 20892-4255, USA
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23
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Guan B, Pungaliya P, Li X, Uquillas C, Mutton LN, Rubin EH, Bieberich CJ. Ubiquitination by TOPORS regulates the prostate tumor suppressor NKX3.1. J Biol Chem 2007; 283:4834-40. [PMID: 18077445 DOI: 10.1074/jbc.m708630200] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The NKX3.1 gene located at 8p21.2 encodes a homeodomain-containing transcription factor that acts as a haploinsufficient tumor suppressor in prostate cancer. Diminished protein expression of NKX3.1 has been observed in prostate cancer precursors and carcinomas. TOPORS is a ubiquitously expressed E3 ubiquitin ligase that can ubiquitinate tumor suppressor p53. Here we report interaction between NKX3.1 and TOPORS. NKX3.1 can be ubiquitinated by TOPORS in vitro and in vivo, and overexpression of TOPORS leads to NKX3.1 proteasomal degradation in prostate cancer cells. Conversely, small interfering RNA-mediated knockdown of TOPORS leads to an increased steady-state level and prolonged half-life of NKX3.1. These data establish TOPORS as a negative regulator of NKX3.1 and implicate TOPORS in prostate cancer progression.
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Affiliation(s)
- Bin Guan
- Department of Biological Sciences, University of Maryland, Baltimore County, Baltimore, Maryland 21250, USA
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24
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Chakarova CF, Papaioannou MG, Khanna H, Lopez I, Waseem N, Shah A, Theis T, Friedman J, Maubaret C, Bujakowska K, Veraitch B, Abd El-Aziz MM, Prescott DQ, Parapuram SK, Bickmore WA, Munro PMG, Gal A, Hamel CP, Marigo V, Ponting CP, Wissinger B, Zrenner E, Matter K, Swaroop A, Koenekoop RK, Bhattacharya SS. Mutations in TOPORS cause autosomal dominant retinitis pigmentosa with perivascular retinal pigment epithelium atrophy. Am J Hum Genet 2007; 81:1098-103. [PMID: 17924349 DOI: 10.1086/521953] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2007] [Accepted: 07/17/2007] [Indexed: 11/03/2022] Open
Abstract
We report mutations in the gene for topoisomerase I-binding RS protein (TOPORS) in patients with autosomal dominant retinitis pigmentosa (adRP) linked to chromosome 9p21.1 (locus RP31). A positional-cloning approach, together with the use of bioinformatics, identified TOPORS (comprising three exons and encoding a protein of 1,045 aa) as the gene responsible for adRP. Mutations that include an insertion and a deletion have been identified in two adRP-affected families--one French Canadian and one German family, respectively. Interestingly, a distinct phenotype is noted at the earlier stages of the disease, with an unusual perivascular cuff of retinal pigment epithelium atrophy, which was found surrounding the superior and inferior arcades in the retina. TOPORS is a RING domain-containing E3 ubiquitin ligase and localizes in the nucleus in speckled loci that are associated with promyelocytic leukemia bodies. The ubiquitous nature of TOPORS expression and a lack of mutant protein in patients are highly suggestive of haploinsufficiency, rather than a dominant negative effect, as the molecular mechanism of the disease and make rescue of the clinical phenotype amenable to somatic gene therapy.
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25
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Hammer E, Heilbronn R, Weger S. The E3 ligase Topors induces the accumulation of polysumoylated forms of DNA topoisomerase I in vitro and in vivo. FEBS Lett 2007; 581:5418-24. [PMID: 17976381 DOI: 10.1016/j.febslet.2007.10.040] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2007] [Revised: 10/22/2007] [Accepted: 10/22/2007] [Indexed: 11/30/2022]
Abstract
Human Topors has originally been identified as binding partner of p53 and DNA topoisomerase I (TOP1). It can function as both an ubiquitin and SUMO-1 E3 ligase for p53. Here we demonstrate that Topors enhances the formation of high-molecular weight SUMO-1 conjugates of TOP1 in a reconstituted in vitro system and also in human osteosarcoma cells, similar to treatment with CPT. In contrast to the situation observed with p53, overall sumoylation levels were rather unaffected. Experiments with TOP1 point mutants strongly suggest that the high-molecular weight conjugates represent SUMO-1 chains formed on a limited number of SUMO-1 acceptor sites.
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Affiliation(s)
- Eva Hammer
- Institute of Virology, Charité Campus Benjamin Franklin, Free University of Berlin, Hindenburgdamm 27, 12203 Berlin, Germany
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26
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Ii T, Mullen JR, Slagle CE, Brill SJ. Stimulation of in vitro sumoylation by Slx5-Slx8: evidence for a functional interaction with the SUMO pathway. DNA Repair (Amst) 2007; 6:1679-91. [PMID: 17669696 PMCID: PMC2100399 DOI: 10.1016/j.dnarep.2007.06.004] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2007] [Revised: 06/13/2007] [Accepted: 06/14/2007] [Indexed: 11/15/2022]
Abstract
The yeast genes SLX5 and SLX8 were identified based on their requirement for viability in the absence of the Sgs1 DNA helicase. Loss of these genes results in genome instability, nibbled colonies, and other phenotypes associated with defects in sumoylation. The Slx5 and Slx8 proteins form a stable complex and each subunit contains a single RING-finger domain at its C-terminus. To determine the physiological function of the Slx5-8 complex, we explored its interaction with the SUMO pathway. Curing 2micro circle from the mutants, suppressed their nibbled colony phenotype and partially improved their growth rate, but did not affect their sensitivity to hydroxyurea. The increase in sumoylation observed in slx5Delta and slx8Delta mutants was found to be dependent on the Siz1 SUMO ligase. Physical interactions between the Slx5-8 complex and both Ubc9 and Smt3 were identified and characterized. Using in vitro reactions, we show that Slx5, Slx8, or the Slx5-8 complex stimulates the formation of SUMO chains and the sumoylation of a test substrate. Interestingly, a functional RING-finger domain is not required for this stimulation in vitro. These biochemical data demonstrate for the first time that the Slx5 and Slx8 complex is capable of interacting directly with the SUMO pathway.
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Affiliation(s)
| | | | | | - Steven J. Brill
- *To whom correspondence should be addressed, Phone (732) 235-4197, Fax (732) 235-4880,
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27
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Yao Z, Duan S, Hou D, Heese K, Wu M. Death effector domain DEDa, a self-cleaved product of caspase-8/Mch5, translocates to the nucleus by binding to ERK1/2 and upregulates procaspase-8 expression via a p53-dependent mechanism. EMBO J 2007; 26:1068-80. [PMID: 17290218 PMCID: PMC1852837 DOI: 10.1038/sj.emboj.7601571] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2006] [Accepted: 01/02/2007] [Indexed: 02/08/2023] Open
Abstract
Activation of the apical caspase-8 is crucial to the extrinsic apoptotic pathway. Although the death effector domain (DED) of caspase-8 has been reported to be involved in death-inducing signaling complex formation, the detailed mechanism of how DED functions in regulating apoptosis remains largely unknown. Here, we demonstrate that the prodomain of the caspase-8/Mch5 can be further cleaved between two tandemly repeated DEDs (DEDa-DEDb) at the amino-acid residue Asp129 by caspase-8 itself. The DEDa fragment generated from the endogenous caspase-8 was detected in isolated nucleoli upon treatment with TRAIL (tumor necrosis factor-related apoptosis-inducing ligand). Cleaved DEDa appears to translocate into the nucleus by association with extracellular signal-regulated protein kinases-1/2 (ERK1/2). Elimination of ERK1/2 expression by RNA interference resulted in a significant attenuation of nuclear entry of DEDa and reduced caspase-8-dependent apoptosis. In the nucleus, DEDa interacts with TOPORS, a p53 and topoisomerase I binding protein, and possibly displaces p53 from TOPORS, allowing p53 to stimulate caspase-8 gene expression. In summary, we postulate a positive feedback loop involving DEDa, which enables the continual replenishment of procaspase-8 during apoptosis.
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Affiliation(s)
- Zhan Yao
- Hefei National Laboratory for Physical Sciences at Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, People's Republic of China
| | - Shanshan Duan
- Hefei National Laboratory for Physical Sciences at Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, People's Republic of China
| | - Dezhi Hou
- Hefei National Laboratory for Physical Sciences at Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, People's Republic of China
| | - Klaus Heese
- Department of Molecular and Cell Biology, School of Biological Sciences, Nanyang Technological University, Singapore
| | - Mian Wu
- Hefei National Laboratory for Physical Sciences at Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, People's Republic of China
- School of Life Sciences, University of Science and Technology of China, 443 Huang-Shan Road, Hefei, Anhui 230027, People's Republic of China. Tel.: +86 551 3607324; Fax: +86 551 3606264; E-mail:
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28
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Capelson M, Corces VG. The ubiquitin ligase dTopors directs the nuclear organization of a chromatin insulator. Mol Cell 2005; 20:105-16. [PMID: 16209949 DOI: 10.1016/j.molcel.2005.08.031] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2005] [Revised: 08/10/2005] [Accepted: 08/29/2005] [Indexed: 10/25/2022]
Abstract
Chromatin insulators are gene regulatory elements implicated in the establishment of independent chromatin domains. The gypsy insulator of D. melanogaster confers its activity through a protein complex that consists of three known components, Su(Hw), Mod(mdg4)2.2, and CP190. We have identified a factor, Drosophila Topoisomerase I-interacting RS protein (dTopors) that interacts with the insulator protein complex and is required for gypsy insulator function. In the absence of Mod(mdg4)2.2, nuclear clustering of insulator complexes is disrupted and insulator activity is compromised. Overexpression of dTopors in the mod(mdg4)2.2 null mutant rescues insulator activity and restores the formation of nuclear insulator bodies. dTopors associates with the nuclear lamina, and mutations in lamin disrupt dTopors localization as well as nuclear organization and activity of the gypsy insulator. Thus, dTopors appears to be involved in the establishment of chromatin organization through its ability to mediate the association of insulator complexes with a fixed nuclear substrate.
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Affiliation(s)
- Maya Capelson
- Department of Biology, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA
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29
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Weger S, Hammer E, Heilbronn R. Topors acts as a SUMO-1 E3 ligase for p53 in vitro and in vivo. FEBS Lett 2005; 579:5007-12. [PMID: 16122737 DOI: 10.1016/j.febslet.2005.07.088] [Citation(s) in RCA: 122] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2005] [Revised: 07/13/2005] [Accepted: 07/18/2005] [Indexed: 12/22/2022]
Abstract
Human Topors, which was originally identified as cellular binding partner of DNA topoisomerase I and of p53, has recently been shown to function as an ubiquitin E3 ligase for p53 in a manner dependent on its N'-terminally located RING finger. Here, we demonstrate that Topors also enhances the conjugation of the small ubiquitin-like modifier 1 (SUMO-1) to p53 in vivo and in a reconstituted in vitro system. The Topors SUMO-1 E3 ligase activity does not depend upon its RING finger motif. In HeLa cells, Topors induced p53 sumoylation was accompanied by an increase in endogenous p53 protein levels. Furthermore, Topors enhances the sumoylation of a variety of other, yet unidentified, cellular proteins.
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Affiliation(s)
- Stefan Weger
- Institute of Infectious Diseases, Department of Virology, Charité Campus Benjamin Franklin, Free University of Berlin, Hindenburgdamm 27, 12203 Berlin, Germany.
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30
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Czubaty A, Girstun A, Kowalska-Loth B, Trzcińska AM, Purta E, Winczura A, Grajkowski W, Staroń K. Proteomic analysis of complexes formed by human topoisomerase I. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2005; 1749:133-41. [PMID: 15848144 DOI: 10.1016/j.bbapap.2005.03.007] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2005] [Revised: 03/08/2005] [Accepted: 03/09/2005] [Indexed: 10/25/2022]
Abstract
Human topoisomerase I is a nuclear enzyme that catalyses DNA relaxation and phosphorylation of SR proteins. Topoisomerase I participates in several protein-protein interactions. We performed a proteomic analysis of protein partners of topoisomerase I. Two methods were applied to proteins of the nuclear extract of HeLa cells: a co-immunoprecipitation and an affinity chromatography combined with mass spectrometry. Complexes formed by topoisomerase I with its protein partners were immunoprecipitated by scleroderma anti-topoisomerase I antibodies. To identify binding sites for the protein partners, baits corresponding to fragments of topoisomerase I were constructed and used in the affinity chromatography. The N-terminal domain and the cap region of the core domain appeared to be the main regions that bound proteins. We identified 36 nuclear proteins that were associated with topoisomerase I. The proteins were mainly involved in RNA metabolism. We found 29 new and confirmed 7 previously identified protein partners of topoisomerase I. More than 40% proteins that associate with the cap region contain two closely spaced RRM domains. Docking calculations identified the RRM domains as a possible site for the interaction of these proteins with the cap region.
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Affiliation(s)
- Alicja Czubaty
- Institute of Biochemistry, Warsaw University, ul. Miecznikowa 1, 02-096 Warszawa, Poland
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31
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Park SY, Cheng YC. Poly(ADP-ribose) polymerase-1 could facilitate the religation of topoisomerase I-linked DNA inhibited by camptothecin. Cancer Res 2005; 65:3894-902. [PMID: 15867389 DOI: 10.1158/0008-5472.can-04-4014] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Poly(ADP-ribose) polymerase-1 (PARP-1) is known to have an important role in camptothecin sensitivity and interacts with topoisomerase I. In the present study, the impact of PARP-1 on the topoisomerase I-DNA complex stabilized by camptothecin was assessed. It was shown that NH2 terminus-truncated topoisomerase I (amino acids 201-765) showed at least 4-fold less sensitivity to camptothecin than full-length topoisomerase I in the oligonucleotide religation assay. PARP-1 could prevent the action of camptothecin on the religation activity of full-length topoisomerase I, which is linked to DNA in a stoichiometrical manner. However, the religation activity of NH2 terminus-truncated topoisomerase I, which is linked to DNA, could not be enhanced by PARP-1 in the presence of camptothecin. Both full-length and NH2 terminus-truncated topoisomerase I interact with PARP-1. This data suggests that PARP-1 destabilizes the topoisomerase I-camptothecin-DNA complex with the participation of the NH2-terminal domain of topoisomerase I. Poly(ADP-ribosyl)ation of topoisomerase I by PARP-1 in the presence its substrate, NAD, could also promote the religation activity of full-length topoisomerase I as well as NH2 terminus-truncated topoisomerase I. PARP-1 inhibitors (3-aminobenzamide, PJ34) could inhibit this process. Therefore, PARP-1 could facilitate the religation activity of topoisomerase I by itself through topoisomerase I-PARP-1 interaction (PARP-1 action) or by the formation of poly(ADP-ribosyl)ation of topoisomerase I (PARP-1/NAD action). This study also implies that PARP-1 and PARP-1/NAD actions need to be highly regulated by cellular factors for camptothecin to exert its cytotoxicity inside the cells. We propose ATP to be one of the important regulatory factors.
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Affiliation(s)
- Shin-Young Park
- Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut 06520-8066, USA
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32
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Coutts AS, La Thangue NB. The p53 response: emerging levels of co-factor complexity. Biochem Biophys Res Commun 2005; 331:778-85. [PMID: 15865933 DOI: 10.1016/j.bbrc.2005.03.150] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2005] [Indexed: 11/26/2022]
Affiliation(s)
- Amanda S Coutts
- Division of Biochemistry and Molecular Biology, Davidson Building, University of Glasgow, Glasgow G12 8QQ, UK
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33
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Lin L, Ozaki T, Takada Y, Kageyama H, Nakamura Y, Hata A, Zhang JH, Simonds WF, Nakagawara A, Koseki H. topors, a p53 and topoisomerase I-binding RING finger protein, is a coactivator of p53 in growth suppression induced by DNA damage. Oncogene 2005; 24:3385-96. [PMID: 15735665 DOI: 10.1038/sj.onc.1208554] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The RING family zinc-finger protein topors (topoisomerase I-binding protein) binds not only topoisomerase I, but also p53 and the AAV-2 Rep78/68 proteins. topors maps to human chromosome 9p21, which contains candidate tumor suppressor genes implicated in small cell lung cancers. In this study, we isolated the murine counterpart of topors and investigated its impact on p53 function. The deduced amino-acid sequence of mouse topors exhibits extensive similarity to human topors. Overexpressed myc-tagged topors associates with and stabilizes p53, and enhances the p53-dependent transcriptional activities of p21(Waf1), MDM2 and Bax promoters and elevates endogenous p21(Waf1) mRNA levels. Overexpression of topors consequently results in the suppression of cell growth by cell cycle arrest and/or by the induction of apoptosis. Taken together, these studies identify topors as a positive regulator of p53. The expression of topors is induced by exposure to the genotoxic reagents cisplatin and camptothecin, a DNA topoisomerase I inhibitor. We therefore postulate that topors mediates p53-dependent cellular responses induced by DNA damage, suggesting its physiological role as a tumor suppressor.
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Affiliation(s)
- Ling Lin
- Department of Molecular Embryology, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan
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34
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Leppard JB, Champoux JJ. Human DNA topoisomerase I: relaxation, roles, and damage control. Chromosoma 2005; 114:75-85. [PMID: 15830206 DOI: 10.1007/s00412-005-0345-5] [Citation(s) in RCA: 161] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2005] [Revised: 03/29/2005] [Accepted: 03/30/2005] [Indexed: 11/28/2022]
Abstract
Human DNA topoisomerase I is an essential enzyme involved in resolving the torsional stress associated with DNA replication, transcription, and chromatin condensation. The catalytic cycle of the enzyme consists of DNA cleavage to form a covalent enzyme-DNA intermediate, DNA relaxation, and finally, re-ligation of the phosphate backbone to restore the continuity of the DNA. Structure/function studies have elucidated a flexible enzyme that relaxes DNA through coordinated, controlled movements of distinct enzyme domains. The cellular roles of topoisomerase I are apparent throughout the nucleus, but the concentration of processes acting on ribosomal DNA results in topoisomerase I accumulation in the nucleolus. Although the activity of topoisomerase I is required in these processes, the enzyme can also have a deleterious effect on cells. In the event that the final re-ligation step of the reaction cycle is prevented, the covalent topoisomerase I-DNA intermediate becomes a toxic DNA lesion that must be repaired. The complexities of the relaxation reaction, the cellular roles, and the pathways that must exist to repair topoisomerase I-mediated DNA damage highlight the importance of continued study of this essential enzyme.
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Affiliation(s)
- John B Leppard
- Department of Microbiology, School of Medicine, University of Washington, P.O. Box 357242, 1959 N.E. Pacific St., Seattle, WA 98195-7242, USA
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35
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Yu D, Khan E, Khaleque MA, Lee J, Laco G, Kohlhagen G, Kharbanda S, Cheng YC, Pommier Y, Bharti A. Phosphorylation of DNA topoisomerase I by the c-Abl tyrosine kinase confers camptothecin sensitivity. J Biol Chem 2004; 279:51851-61. [PMID: 15448168 DOI: 10.1074/jbc.m404396200] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
DNA topoisomerase I (topo I) is involved in the regulation of DNA supercoiling, gene transcription, recombination, and DNA repair. The anticancer agent camptothecin specifically targets topo I. The mechanisms responsible for the regulation of topo I in cells, however, are not known. This study demonstrates that c-Abl-dependent phosphorylation up-regulates topo I activity. The c-Abl SH3 domain bound directly to the N-terminal region of topo I. The results demonstrate that c-Abl phosphorylated topo I at Tyr268 in core subdomain II. c-Abl-mediated phosphorylation of topo I Tyr268 in vitro and in cells conferred activation of the topo I isomerase function. Moreover, activation of c-Abl by treatment of cells with ionizing radiation was associated with c-Abl-dependent phosphorylation of topo I and induction of topo I activity. The functional significance of the c-Abl/topo I interaction is supported by the findings that (i) mutant topo I(Y268F) exhibited loss of c-Abl-induced topo I activity, and (ii) c-Abl-/- cells were deficient in the accumulation of protein-linked DNA breaks. In addition, loss of topo I phosphorylation in c-Abl-deficient cells conferred resistance to camptothecin-induced apoptosis. These findings collectively support a model in which c-Abl-mediated phosphorylation of topo I is functionally important to topo I activity and sensitivity to topo I poisons.
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Affiliation(s)
- Donghui Yu
- Department of Adult Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts 02115, USA
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36
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Saleem A, Dutta J, Malegaonkar D, Rasheed F, Rasheed Z, Rajendra R, Marshall H, Luo M, Li H, Rubin EH. The topoisomerase I- and p53-binding protein topors is differentially expressed in normal and malignant human tissues and may function as a tumor suppressor. Oncogene 2004; 23:5293-300. [PMID: 15107820 DOI: 10.1038/sj.onc.1207700] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Topors was identified recently as a human protein that binds to topoisomerase I and p53. Topors contains a highly conserved RING domain and localizes in promyelocytic leukemia nuclear bodies. Relatively little is known regarding topors expression patterns or function. We now demonstrate that topors mRNA and protein are widely expressed in normal human tissues. By contrast, topors mRNA and protein levels are decreased or undetectable in colon adenocarcinomas relative to normal colon tissue, and expression of the topors protein is not detectable in several colon cancer cell lines. The human TOPORS gene is located on chromosome 9p21, with loss of heterozygosity in this region frequently observed in several different malignancies. While we were unable to detect loss of heterozygosity of the TOPORS gene in 16 sporadic colon cancer cases, increased methylation of a CpG island in the TOPORS promoter was evident in colon adenocarcinoma specimens relative to matched normal tissues. Additional studies indicate that forced expression of topors inhibits cellular proliferation and is associated with an accumulation of cells in the G(0)/G(1) phase of the cell cycle. This effect is independent of the topors RING domain and maps to a C-terminal region of the protein. These results suggest that topors functions as a negative regulator of cell growth, and possibly as a tumor suppressor.
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Affiliation(s)
- Ahamed Saleem
- Department of Pharmacology, The Cancer Institute of New Jersey, Robert Wood Johnson Medical School, University of Medicine and Dentistry of New Jersey, New Brunswick, NJ, USA
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37
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Rajendra R, Malegaonkar D, Pungaliya P, Marshall H, Rasheed Z, Brownell J, Liu LF, Lutzker S, Saleem A, Rubin EH. Topors functions as an E3 ubiquitin ligase with specific E2 enzymes and ubiquitinates p53. J Biol Chem 2004; 279:36440-4. [PMID: 15247280 DOI: 10.1074/jbc.c400300200] [Citation(s) in RCA: 148] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The human topoisomerase I- and p53-binding protein topors contains a highly conserved, N-terminal C3HC4-type RING domain that is homologous to the RING domains of known E3 ubiquitin ligases. We demonstrate that topors functions in vitro as a RING-dependent E3 ubiquitin ligase with the E2 enzymes UbcH5a, UbcH5c, and UbcH6 but not with UbcH7, CDC34, or UbcH2b. Additional studies indicate that a conserved tryptophan within the topors RING domain is required for ubiquitination activity. Furthermore, both in vitro and cellular studies implicate p53 as a ubiquitination substrate for topors. Similar to MDM2, overexpression of topors results in a proteasome-dependent decrease in p53 protein expression in a human osteosarcoma cell line. These results are similar to the recent finding that a Drosophila topors orthologue ubiquitinates the Hairy transcriptional repressor and suggest that topors functions as a ubiquitin ligase for multiple transcription factors.
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Affiliation(s)
- Rajeev Rajendra
- Department of Pharmacology, The Cancer Institute of New Jersey, Robert Wood Johnson Medical School, University of Medicine and Dentistry of New Jersey, New Brunswick, NJ 08901, USA
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38
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Zhang HF, Tomida A, Koshimizu R, Ogiso Y, Lei S, Tsuruo T. Cullin 3 promotes proteasomal degradation of the topoisomerase I-DNA covalent complex. Cancer Res 2004; 64:1114-21. [PMID: 14871846 DOI: 10.1158/0008-5472.can-03-2858] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
DNA topoisomerase I (TOP1)-DNA covalent complexes are the initial lesions produced by antitumor camptothecins (CPTs). The TOP1-directed drugs stimulate degradation of TOP1 via the ubiquitin-proteasome pathway. We found that proteasome inhibition prevents degradation of DNA-bound TOP1 and sustains high levels of covalent complexes, thus enhancing CPT-induced cell death. Consistent with this, increased degradation of TOP1-DNA covalent complexes was seen in acquired CPT-resistant cells. We found that the resistant cells showed elevated expressions of Cul3, a member of the cullin family of E3 ubiquitin ligases. The reduction in Cul3 expression by small interfering RNA decreased degradation of TOP1-DNA covalent complexes. Conversely, Cul3 overexpression by stable transfection promoted covalent complex degradation and reduced CPT-induced cell death without affecting basal TOP1 expression levels. These results indicate that Cul3, by promoting proteasomal degradation of TOP1-DNA covalent complexes, becomes an important regulator for cellular CPT sensitivity.
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Affiliation(s)
- Hua-Feng Zhang
- Institute of Molecular and Cellular Biosciences, The University of Tokyo, Tokyo, Japan
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39
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Secombe J, Parkhurst SM. Drosophila Topors Is a RING Finger-containing Protein That Functions as a Ubiquitin-protein Isopeptide Ligase for the Hairy Basic Helix-Loop-Helix Repressor Protein. J Biol Chem 2004; 279:17126-33. [PMID: 14871887 DOI: 10.1074/jbc.m310097200] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Transcriptional repression plays an essential role in many aspects of metazoan development. Drosophila hairy is a primary pair-rule gene encoding a basic helix-loop-helix class transcriptional repressor that is required for proper segmentation. Previous characterization of Hairy-binding proteins has implicated two different classes of histone deacetylase as mediators of Hairy repression. Here, we present the characterization of a novel Hairy-interacting protein (dTopors) that binds specifically to the basic region of Hairy, but does not affect the ability of Hairy to bind DNA. By reducing the gene dose of dtopors, we demonstrate that it acts genetically as an antagonist of Hairy-mediated transcriptional repression. Consistent with this genetic interaction, we show that that recombinant dTopors protein possesses ubiquitin-protein isopeptide ligase activity in vitro and that dTopors mediates Hairy polyubiquitination and can lead to Hairy degradation. This work provides the first evidence that regulated proteolysis of Hairy is required for correct segmentation.
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Affiliation(s)
- Julie Secombe
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109-1024, USA
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40
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Alessandri M, Beretta GL, Ferretti E, Mancia A, Khobta A, Capranico G. Enhanced CPT Sensitivity of Yeast Cells and Selective Relaxation of Gal4 Motif-containing DNA by Novel Gal4–Topoisomerase I Fusion Proteins. J Mol Biol 2004; 337:295-305. [PMID: 15003448 DOI: 10.1016/j.jmb.2004.01.032] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2003] [Revised: 01/14/2004] [Accepted: 01/20/2004] [Indexed: 10/26/2022]
Abstract
Human topoisomerase I-B (Top1) efficiently relaxes DNA supercoils during basic cellular processes, and can be transformed into a DNA-damaging agent by antitumour drugs, enzyme mutations and DNA lesions. Here, we describe Gal4-Top1 chimeric proteins (GalTop) with an N-terminal truncation of Top1, and mutations of the Gal4 Zn-cluster and/or Top1 domains that impair their respective DNA-binding activities. Expression levels of chimeras were similar in yeast cells, however, GalTop conferred an increased CPT sensitivity to RAD52- yeast cells as compared to a GalTop with mutations of the Gal4 domain, showing that a functional Gal4 domain can alter in vivo functions of Top1. In vitro enzyme activity was tested with a DNA relaxation assay using negatively supercoiled plasmids with 0 to 5 Gal4 consensus motifs. Only GalTop with a functional Gal4 domain could direct DNA relaxation activity of Top1 specifically to DNA molecules containing Gal4 motifs. By using a substrate competition assay, we could demonstrate that the Gal4-anchored Top1 remains functional and efficiently relax DNA substrates in cis. The enhanced CPT sensitivity of GalTop in yeast cells may then be due to alterations of the chromatin-binding activity of Top1. The GalTop chimeras may indeed mimic a normal mechanism by which Top1 is recruited to chromatin sites in living cells. Such hybrid Top1s may be helpful in further dissecting enzyme functions, and constitute a prototype of a site-specific DNA cutter endowed with high cell lethality.
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Affiliation(s)
- Marco Alessandri
- Alma Mater Studiorum-University of Bologna, G. Moruzzi Department of Biochemistry, via S. Giacomo 11, 40126 Bologna, Italy
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41
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Christensen MO, Barthelmes HU, Boege F, Mielke C. Residues 190-210 of human topoisomerase I are required for enzyme activity in vivo but not in vitro. Nucleic Acids Res 2004; 31:7255-63. [PMID: 14654701 PMCID: PMC291868 DOI: 10.1093/nar/gkg927] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
DNA-topoisomerase I (topo I) unwinds the DNA- double helix by cutting one strand and allowing rotation of the other. In vitro, this function does not require the N-terminal domain of the enzyme, which is believed to regulate cellular properties. To assess this role, we studied the cellular distribution and mobility of green fluorescent protein-chimera of human topo I lacking either the entire N-terminal domain or a portion of it. We find that topo I truncated up to position 210 is not stabilized by camptothecin in covalent DNA-complexes inside a living cell, whereas in vitro it retains full DNA-relaxation activity, and is targeted by camptothecin in the usual manner. This difference is not shared with a fragment lacking the N-terminal domain up to position 190, indicating that residues 190-210 play a crucial role for the activity of the enzyme in its physiological environment, but not in vitro. Since it is impossible to discriminate in vivo whether this region is required for topo I to form covalent DNA intermediates in the cell, or just for camptothecin to bind and stabilize such complexes, we could not explain precisely these cellular observations. However, inactivity in vivo of the enzyme lacking this region is indicated by a lesser cytotoxicity.
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Affiliation(s)
- Morten O Christensen
- Institute of Clinical Chemistry and Laboratory Diagnostics, Heinrich-Heine-University, Medical School, Moorenstrasse 5, D-40225 Duesseldorf, Germany
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42
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Abstract
DNA topoisomerases are a class of enzymes that alter the topology of DNA and are targets of several anticancer drugs. Camptothecins (CPTs) are a relatively new family of compounds that specifically target topoisomerase I (Top1). These compounds "poison" Top1 by binding to the Top1-DNA complex in a manner that prevents the religation of DNA. Topotecan and irinotecan are two CPTs that are approved for the treatment of a variety of malignancies, including colorectal, ovarian, and small cell lung cancers, as well as myeloid malignancies. Although CPTs have proven to be effective anticancer drugs, resistance is still a critical clinical problem. The mechanisms underlying de novo and acquired clinical resistance to CPTs and the newer classes of Top1 poisons are unclear. However, based on preclinical studies, it is likely that clinical resistance to these drugs is the result of: (1) inadequate accumulation of drug in the tumor, (2) resistance-conferring alterations in Top1, or (3) alterations in the cellular response to the Top1-CPT interaction. This review will focus on the current knowledge regarding mechanisms of resistance to CPTs and other Top1-targeting drugs.
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Affiliation(s)
- Zeshaan A Rasheed
- The Cancer Institute of New Jersey, Department of Molecular and Cellular Pharmacology, UMDNJ-Robert Wood Johnson Medical School, 195 Little Albany Street, New Brunswick, NJ 08901, USA.
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43
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Weger S, Hammer E, Engstler M. The DNA topoisomerase I binding protein topors as a novel cellular target for SUMO-1 modification: characterization of domains necessary for subcellular localization and sumolation. Exp Cell Res 2003; 290:13-27. [PMID: 14516784 DOI: 10.1016/s0014-4827(03)00292-1] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Over the past years, modification by covalent attachment of SUMO (small ubiquitin-like modifier) has been demonstrated for of a number of cellular and viral proteins. While increasing evidence suggests a role for SUMO modification in the regulation of protein-protein interactions and/or subcellular localization, most SUMO targets are still at large. In this report we show that Topors, a Topoisomerase I and p53 interacting protein of hitherto unknown function, presents a novel cellular target for SUMO-1 modification. In a yeast two-hybrid system, Topors interacted with both SUMO-1 and the SUMO-1 conjugating enzyme UBC9. Multiple SUMO-1 modified forms of Topors could be detected after cotransfection of exogenous SUMO-1 and Topors induced the colocalization of a YFP tagged SUMO-1 protein in a speckled pattern in the nucleus. A subset of these Topors' nuclear speckles were closely associated with the PML nuclear bodies (POD, ND10). A central domain comprising Topors residues 437 to 574 was sufficient for both sumolation and localization to nuclear speckles. One SUMO-1 acceptor site at lysine residue 560 could be identified within this region. However, sumolation-deficient Topors mutants showed that sumolation obviously is not required for localization to nuclear speckles.
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Affiliation(s)
- Stefan Weger
- Department of Virology, Institute of Infectious Diseases, Free University of Berlin, Hindenburgdamm 27, 12203 Berlin, Germany.
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44
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Minenkova O, Pucci A, Pavoni E, De Tomassi A, Fortugno P, Gargano N, Cianfriglia M, Barca S, De Placido S, Martignetti A, Felici F, Cortese R, Monaci P. Identification of tumor-associated antigens by screening phage-displayed human cDNA libraries with sera from tumor patients. Int J Cancer 2003; 106:534-544. [PMID: 12845649 DOI: 10.1002/ijc.11269] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Screening cDNA libraries from solid human tumors with sera of autologous patients (SEREX) has proven to be a powerful approach to identifying tumor antigens recognized by the humoral arm of the immune system. In many cases, application of this methodology has led to the discovery of novel tumor antigens as unknown gene products. We tried to improve the potency of the SEREX approach by combining it with phage-display technology. We designed a new lambda vector to express protein fragments as N-terminal fusions to the D capsid protein and generated high-complexity cDNA libraries from human breast carcinoma cell lines and solid tumors. Screening these phage-displayed libraries required limited amounts of sera from patients and efficiently identified several tumor antigens specifically reacting with sera from breast cancer patients.
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Affiliation(s)
| | - Andrea Pucci
- Kenton Labs, c/o Sigma Tau, Pomezia (Roma), Italy
| | | | | | | | | | - Maurizio Cianfriglia
- Laboratorio di Immunologia, Reparto Immunologia dei Tumori, Istituto Superiore di Sanità, Roma, Italy
| | - Stefano Barca
- Laboratorio di Immunologia, Reparto Immunologia dei Tumori, Istituto Superiore di Sanità, Roma, Italy
| | - Sabino De Placido
- Dipartimento di Endocrinologia ed Oncologia Molecolare e Clinica, Università di Napoli Federico II, Napoli, Italy
| | - Angelo Martignetti
- Dipartimento di Endocrinologia ed Oncologia Molecolare e Clinica, Università di Napoli Federico II, Napoli, Italy
| | | | - Riccardo Cortese
- Istituto di Ricerche di Biologia Molecolare P. Angeletti, Pomezia (Roma), Italy
| | - Paolo Monaci
- Istituto di Ricerche di Biologia Molecolare P. Angeletti, Pomezia (Roma), Italy
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Qiu J, Gunaratne P, Peterson LE, Khurana D, Walsham N, Loulseged H, Karni RJ, Roussel E, Gibbs RA, Margolin JF, Gingras MC. Novel potential ALL low-risk markers revealed by gene expression profiling with new high-throughput SSH-CCS-PCR. Leukemia 2003; 17:1891-900. [PMID: 12970791 DOI: 10.1038/sj.leu.2403073] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The current systems of risk grouping in pediatric acute lymphoblastic leukemia (ALL) fail to predict therapeutic success in 10-35% of patients. To identify better predictive markers of clinical behavior in ALL, we have developed an integrated approach for gene expression profiling that couples suppression subtractive hybridization, concatenated cDNA sequencing, and reverse transcriptase real-time quantitative PCR. Using this approach, a total of 600 differentially expressed genes were identified between t(4;11) ALL and pre-B ALL with no determinant chromosomal translocation. The expression of 67 genes was analyzed in different cytogenetic ALL subgroups and B lymphocytes isolated from healthy donors. Three genes, BACH1, TP53BPL, and H2B/S, were consistently expressed as a significant cluster associated with the low-risk ALL subgroups. A total of 42 genes were differentially expressed in ALL vs normal B lymphocytes, with no specific association with any particular ALL subgroups. The remaining 22 genes were part of a specific expression profile associated with the hyperdiploid, t(12;21), or t(4;11) subgroups. Using an unsupervised hierarchical cluster analysis, the discriminating power of these specific expression profiles allowed the clustering of patients according to their subgroups. These genes could help to understand the difference in treatment response and become therapeutical targets to improve ALL clinical outcomes.
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Affiliation(s)
- J Qiu
- Texas Children's Cancer Center and Department of Pediatrics, department of Baylor College of Medicine, Baylor College of Medicine, Houston, TX 77030, USA
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Scott RE, Giannakouros T, Gao S, Peidis P. Functional potential of P2P-R: a role in the cell cycle and cell differentiation related to its interactions with proteins that bind to matrix associated regions of DNA? J Cell Biochem 2003; 90:6-12. [PMID: 12938151 DOI: 10.1002/jcb.10618] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
P2P-R is the alternately spliced product of the P2P-R/PACT gene in that P2P-R lacks one exon encoding 34 amino acids. The 250 kDa P2P-R protein is the predominate product expressed in multiple murine cell lines. It is a highly basic protein that contains multiple domains including an N-terminal RING type zinc finger, a proline rich domain, an RS region, and a C-terminal lysine-rich domain. P2P-R binds the p53 and the Rb1 tumor suppressors and is phosphorylated by the cdc2 and SRPK1a protein kinases. P2P-R also interacts with scaffold attachment factor-B (SAF-B), a well characterized MARs (for matrix attachment regions) binding factor, and may interact with nucleolin, another MARs binding factor. In addition, P2P-R binds single strand DNA (ssDNA). The expression of P2P-R is regulated by differentiation and cell cycle events. P2P-R mRNA is markedly repressed during differentiation, whereas immunoreactive P2P-R protein levels are >10-fold higher in mitotic than in G(0) cells. The localization of P2P-R also is modulated during the cell cycle. During interphase, P2P-R is present primarily in nucleoli and nuclear speckles whereas during mitosis, P2P-R associates with the periphery of chromosomes. Overexpression of near full length P2P-R induces mitotic arrest in prometaphase and mitotic apoptosis, and overexpression of selected P2P-R segments also can promote apoptosis. This compendium of data supports the possibility that P2P-R may form complexes with the Rb1 and/or p53 tumor suppressors and MARs-related factors, in a cell cycle and cell differentiation-dependent manner, to influence gene transcription/expression and nuclear organization.
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Affiliation(s)
- Robert E Scott
- Department of Pathology, University of Tennessee Health Science Center, Memphis, Tennessee 38163, USA.
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Desai SD, Zhang H, Rodriguez-Bauman A, Yang JM, Wu X, Gounder MK, Rubin EH, Liu LF. Transcription-dependent degradation of topoisomerase I-DNA covalent complexes. Mol Cell Biol 2003; 23:2341-50. [PMID: 12640119 PMCID: PMC150741 DOI: 10.1128/mcb.23.7.2341-2350.2003] [Citation(s) in RCA: 115] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Topoisomerase I (Top I)-DNA covalent complexes represent a unique type of DNA lesion whose repair and processing remain unclear. In this study, we show that Top I-DNA covalent complexes transiently arrest RNA transcription in normal nontransformed cells. Arrest of RNA transcription is coupled to activation of proteasomal degradation of Top I and the large subunit of RNA polymerase II. Recovery of transcription occurs gradually and depends on both proteasomal degradation of Top I and functional transcription-coupled repair (TCR). These results suggest that arrest of the RNA polymerase elongation complex by the Top I-DNA covalent complex triggers a 26S proteasome-mediated signaling pathway(s) leading to degradation of both Top I and the large subunit of RNA polymerase II. We propose that proteasomal degradation of Top I and RNA polymerase II precedes repair of the exposed single-strand breaks by TCR.
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Affiliation(s)
- Shyamal D Desai
- Department of Pharmacology, UMDNJ-Robert Wood Johnson Medical School, Piscataway, New Jersey 08854, USA
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Trzcińska AM, Girstun A, Piekiełko A, Kowalska-Loth B, Staroń K. Potential protein partners for the N-terminal domain of human topoisomerase I revealed by phage display. Mol Biol Rep 2002; 29:347-52. [PMID: 12549820 DOI: 10.1023/a:1021237021338] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Phage display procedure was applied to the N-terminal domain of human topoisomerase I. The consensus sequence identified for clones binding to the N-terminal domain was found in 35 human proteins that are either permanently or temporarily located in the nucleus. They are in majority involved in the DNA repair, transcription, RNA metabolism or cell cycle control. Four of identified proteins: Bub3 protein, Cockayne syndrome protein A, damaged DNA binding protein 2 and GRWD protein belong to WD-repeat proteins and their sequences recognized by the N-terminal domain are identically localized.
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Affiliation(s)
- Agata M Trzcińska
- Institute of Biochemistry, Warsaw University, ul. Miecznikowa 1, 02-093 Warsaw, Poland
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Søe K, Hartmann H, Schlott B, Stevnsner T, Grosse F. The tumor suppressor protein p53 stimulates the formation of the human topoisomerase I double cleavage complex in vitro. Oncogene 2002; 21:6614-23. [PMID: 12242659 DOI: 10.1038/sj.onc.1205912] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2002] [Revised: 07/24/2002] [Accepted: 07/25/2002] [Indexed: 11/08/2022]
Abstract
Previous studies have shown that human topoisomerase I interacts directly with the tumor-suppressor protein p53. In the past few years it has repeatedly been suggested that topoisomerase I and p53 may play a joint role in the response to genotoxic stress. This led to the suggestion that p53 and human topoisomerase I may cooperate in the process of DNA repair and/or apoptosis. Recently we have demonstrated that a human topoisomerase I cleavage complex can be recognized by an additional topoisomerase I molecule and thereby form a so-called double cleavage complex. The double cleavage complex creates an about 13 nucleotides long single-stranded gap that may provide an entry site for recombinational repair events. Here we demonstrate that p53 stimulates both the DNA relaxation activity as well as the formation of the human topoisomerase I double cleavage complex by at least a factor of six. Stimulation of topoisomerase I activity by p53 is mediated via the central part of topoisomerase I. We also show that human, bovine, and murine p53 stimulate human topoisomerase I relaxation activity equally well. From these results it is conceivable that p53's stimulatory activity on topoisomerase I may play a role in DNA recombination and repair as well as in apoptosis.
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Affiliation(s)
- Kent Søe
- Institute of Molecular Biotechnology, Department of Biochemistry, Beutenbergstrasse 11, D-07745 Jena, Germany
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