1
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Jones RM, Ruiz JH, Scaramuzza S, Nath S, Liu C, Henklewska M, Natsume T, Bristow RG, Romero F, Kanemaki MT, Gambus A. Characterizing replisome disassembly in human cells. iScience 2024; 27:110260. [PMID: 39055910 PMCID: PMC11269944 DOI: 10.1016/j.isci.2024.110260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Revised: 03/22/2024] [Accepted: 06/10/2024] [Indexed: 07/28/2024] Open
Abstract
To ensure timely duplication of the entire eukaryotic genome, thousands of replication machineries (replisomes) act on genomic DNA at any time during S phase. In the final stages of this process, replisomes are unloaded from chromatin. Unloading is driven by polyubiquitylation of MCM7, a subunit of the terminated replicative helicase, and processed by p97/VCP segregase. Most of our knowledge of replication termination comes from model organisms, and little is known about how this process is executed and regulated in human somatic cells. Here we show that replisome disassembly in this system requires CUL2LRR1-driven MCM7 ubiquitylation, p97, and UBXN7 for unloading and provide evidence for "backup" mitotic replisome disassembly, demonstrating conservation of such mechanisms. Finally, we find that small-molecule inhibitors against Cullin ubiquitin ligases (CULi) and p97 (p97i) affect replisome unloading but also lead to induction of replication stress in cells, which limits their usefulness to specifically target replisome disassembly processes.
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Affiliation(s)
- Rebecca M. Jones
- Institute of Cancer and Genomic Sciences, Birmingham Centre for Genome Biology, University of Birmingham, Birmingham, UK
| | - Joaquin Herrero Ruiz
- Institute of Cancer and Genomic Sciences, Birmingham Centre for Genome Biology, University of Birmingham, Birmingham, UK
- Department of Genetics, The Graduate University for Advanced Studies (SOKENDAI), Mishima, Shizuoka, Japan
| | - Shaun Scaramuzza
- Institute of Cancer and Genomic Sciences, Birmingham Centre for Genome Biology, University of Birmingham, Birmingham, UK
| | - Sarmi Nath
- Institute of Cancer and Genomic Sciences, Birmingham Centre for Genome Biology, University of Birmingham, Birmingham, UK
| | - Chaoyu Liu
- Institute of Cancer and Genomic Sciences, Birmingham Centre for Genome Biology, University of Birmingham, Birmingham, UK
| | - Marta Henklewska
- Institute of Cancer and Genomic Sciences, Birmingham Centre for Genome Biology, University of Birmingham, Birmingham, UK
| | - Toyoaki Natsume
- Department of Chromosome Science, National Institute of Genetics, Research Organization of Information and Systems, Mishima, Shizuoka, Japan
- Department of Genetics, The Graduate University for Advanced Studies (SOKENDAI), Mishima, Shizuoka, Japan
| | - Robert G. Bristow
- Cancer Research UK – Manchester Institute, Manchester Cancer Research Center, Manchester, UK
| | - Francisco Romero
- Department of Microbiology, University of Seville, Seville, Spain
| | - Masato T. Kanemaki
- Department of Chromosome Science, National Institute of Genetics, Research Organization of Information and Systems, Mishima, Shizuoka, Japan
- Department of Genetics, The Graduate University for Advanced Studies (SOKENDAI), Mishima, Shizuoka, Japan
- Department of Biological Science, The University of Tokyo, Tokyo, Japan
| | - Agnieszka Gambus
- Institute of Cancer and Genomic Sciences, Birmingham Centre for Genome Biology, University of Birmingham, Birmingham, UK
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2
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Ganipineni VDP, Idavalapati ASKK, Tamalapakula SS, Moparthi V, Potru M, Owolabi OJ. Depression and Hand-Grip: Unraveling the Association. Cureus 2023; 15:e38632. [PMID: 37159619 PMCID: PMC10163904 DOI: 10.7759/cureus.38632] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/06/2023] [Indexed: 05/11/2023] Open
Abstract
This review article explores the association between hand-grip strength and depression. A total of 14 studies were carefully considered to provide a comprehensive analysis of the topic. The studies reveal a consistent association between low hand-grip strength and depressive symptoms, independent of age, gender, and chronic disease status. The evidence suggests that hand-grip strength assessment could be a useful tool for identifying individuals at risk of depression, particularly older adults and those with chronic diseases. Incorporating physical activity and strength training into treatment plans can contribute to better mental health outcomes. Hand-grip strength assessment can also be used as a monitoring tool to track changes in physical and mental health over time in individuals with depression. Healthcare professionals should consider the relationship between hand-grip strength and depression when evaluating patients and developing treatment plans. The findings from this comprehensive clinical review have important clinical implications and highlight the importance of considering physical health factors in the context of mental health.
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Affiliation(s)
- Vijay Durga Pradeep Ganipineni
- Department of General Medicine, SRM Medical College Hospital and Research Center, Chennai, IND
- Department of General Medicine, Andhra Medical College/King George Hospital, Visakhapatnam, IND
| | | | | | - Vagdevi Moparthi
- Department of Medicine, Dr. Pinnamaneni Siddhartha Institute of Medical Sciences and Research Foundation, Vijayawada, IND
| | - Monica Potru
- Department of Medicine, Guntur Medial College, Guntur, IND
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3
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Pelletier B, Duhamel S, Tambutet G, Jarvis S, Cléroux P, David M, Tanguay PL, Voisin L, James C, Lavoie R, Gareau Y, Flynn-Robitaille J, Lorca T, Ruel R, Marinier A, Meloche S. Discovery of Benzodiazepine-Based Inhibitors of the E2 Enzyme UBCH10 from a Cell-Based p21 Degradation Screen. ACS Chem Biol 2023; 18:1039-1046. [PMID: 37097827 DOI: 10.1021/acschembio.2c00909] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/26/2023]
Abstract
p21Cip1 (p21) is a universal cyclin-dependent kinase (CDK) inhibitor that halts cell proliferation and tumor growth by multiple mechanisms. The expression of p21 is often downregulated in cancer cells as a result of the loss of function of transcriptional activators, such as p53, or the increased degradation rate of the protein. To identify small molecules that block the ubiquitin-mediated degradation of p21 as a future avenue for cancer drug discovery, we have screened a compound library using a cell-based reporter assay of p21 degradation. This led to the identification of a benzodiazepine series of molecules that induce the accumulation of p21 in cells. Using a chemical proteomic strategy, we identified the ubiquitin-conjugating enzyme UBCH10 as a cellular target of this benzodiazepine series. We show that an optimized benzodiazepine analogue inhibits UBCH10 ubiquitin-conjugating activity and substrate proteolysis by the anaphase-promoting complex.
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Affiliation(s)
- Benoit Pelletier
- Institute for Research in Immunology and Cancer, Montreal, Quebec H3C 3J7, Canada
| | - Stéphanie Duhamel
- Institute for Research in Immunology and Cancer, Montreal, Quebec H3C 3J7, Canada
| | - Guillaume Tambutet
- Institute for Research in Immunology and Cancer, Montreal, Quebec H3C 3J7, Canada
| | - Scott Jarvis
- Institute for Research in Immunology and Cancer, Montreal, Quebec H3C 3J7, Canada
| | - Patrick Cléroux
- Institute for Research in Immunology and Cancer, Montreal, Quebec H3C 3J7, Canada
| | - Maud David
- Institute for Research in Immunology and Cancer, Montreal, Quebec H3C 3J7, Canada
| | - Pierre-Luc Tanguay
- Institute for Research in Immunology and Cancer, Montreal, Quebec H3C 3J7, Canada
| | - Laure Voisin
- Institute for Research in Immunology and Cancer, Montreal, Quebec H3C 3J7, Canada
| | - Clint James
- Institute for Research in Immunology and Cancer, Montreal, Quebec H3C 3J7, Canada
| | - Rico Lavoie
- Institute for Research in Immunology and Cancer, Montreal, Quebec H3C 3J7, Canada
| | - Yves Gareau
- Institute for Research in Immunology and Cancer, Montreal, Quebec H3C 3J7, Canada
| | | | - Thierry Lorca
- Université de Montpellier, Centre de Recherche en Biologie Cellulaire de Montpellier (CRBM), CNRS, UMR 5237, 34293 Montpellier Cedex 05, France
| | - Réjean Ruel
- Institute for Research in Immunology and Cancer, Montreal, Quebec H3C 3J7, Canada
| | - Anne Marinier
- Institute for Research in Immunology and Cancer, Montreal, Quebec H3C 3J7, Canada
- Department of Chemistry, Université de Montréal, Montreal, Quebec H3C 3J7, Canada
- Department of Pharmacology and Physiology, Université de Montréal, Montreal, Quebec H3C 3J7, Canada
| | - Sylvain Meloche
- Institute for Research in Immunology and Cancer, Montreal, Quebec H3C 3J7, Canada
- Department of Pharmacology and Physiology, Université de Montréal, Montreal, Quebec H3C 3J7, Canada
- Molecular Biology Program, Faculty of Medicine, Université de Montréal, Montreal, Quebec H3C 3J7, Canada
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4
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A genetic correlation and bivariate genome-wide association study of grip strength and depression. PLoS One 2022; 17:e0278392. [PMID: 36520780 PMCID: PMC9754196 DOI: 10.1371/journal.pone.0278392] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2022] [Accepted: 11/15/2022] [Indexed: 12/23/2022] Open
Abstract
Grip strength is an important biomarker reflecting muscle strength, and depression is a psychiatric disorder all over the world. Several studies found a significant inverse association between grip strength and depression, and there is also evidence for common physiological mechanisms between them. We used twin data from Qingdao, China to calculate genetic correlations, and we performed a bivariate GWAS to explore potential SNPs, genes, and pathways in common between grip strength and depression. 139 pairs of Dizygotic twins were used for bivariate GWAS. VEAGSE2 and PASCAL software were used for gene-based analysis and pathway enrichment analysis, respectively. And the resulting SNPs were subjected to eQTL analysis and pleiotropy analysis. The genetic correlation coefficient between grip strength and depression was -0.41 (-0.96, -0.15). In SNP-based analysis, 7 SNPs exceeded the genome-wide significance level (P<5×10-8) and a total of 336 SNPs reached the level of suggestive significance (P<1×10-5). Gene-based analysis and pathway-based analysis identified genes and pathways related to muscle strength and the nervous system. The results of eQTL analysis were mainly enriched in tissues such as the brain, thyroid, and skeletal muscle. Pleiotropy analysis shows that 9 of the 15 top SNPs were associated with both grip strength and depression. In conclusion, this bivariate GWAS identified potentially common pleiotropic SNPs, genes, and pathways in grip strength and depression.
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5
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Le TT, Ainsworth J, Polo Rivera C, Macartney T, Labib KP. Reconstitution of human CMG helicase ubiquitylation by CUL2LRR1 and multiple E2 enzymes. Biochem J 2021; 478:2825-2842. [PMID: 34195792 PMCID: PMC8331092 DOI: 10.1042/bcj20210315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Revised: 06/25/2021] [Accepted: 06/29/2021] [Indexed: 11/17/2022]
Abstract
Cullin ubiquitin ligases drive replisome disassembly during DNA replication termination. In worm, frog and mouse cells, CUL2LRR1 is required to ubiquitylate the MCM7 subunit of the CMG helicase. Here, we show that cullin ligases also drive CMG-MCM7 ubiquitylation in human cells, thereby making the helicase into a substrate for the p97 unfoldase. Using purified human proteins, including a panel of E2 ubiquitin-conjugating enzymes, we have reconstituted CMG helicase ubiquitylation, dependent upon neddylated CUL2LRR1. The reaction is highly specific to CMG-MCM7 and requires the LRR1 substrate targeting subunit, since replacement of LRR1 with the alternative CUL2 adaptor VHL switches ubiquitylation from CMG-MCM7 to HIF1. CUL2LRR1 firstly drives monoubiquitylation of CMG-MCM7 by the UBE2D class of E2 enzymes. Subsequently, CUL2LRR1 activates UBE2R1/R2 or UBE2G1/G2 to extend a single K48-linked ubiquitin chain on CMG-MCM7. Thereby, CUL2LRR1 converts CMG into a substrate for p97, which disassembles the ubiquitylated helicase during DNA replication termination.
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Affiliation(s)
- Thanh Thi Le
- The MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, U.K
| | - Johanna Ainsworth
- The MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, U.K
| | - Cristian Polo Rivera
- The MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, U.K
| | - Thomas Macartney
- The MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, U.K
| | - Karim P.M. Labib
- The MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, U.K
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6
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The Involvement of Ubiquitination Machinery in Cell Cycle Regulation and Cancer Progression. Int J Mol Sci 2021; 22:ijms22115754. [PMID: 34072267 PMCID: PMC8198665 DOI: 10.3390/ijms22115754] [Citation(s) in RCA: 49] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 05/12/2021] [Accepted: 05/26/2021] [Indexed: 02/07/2023] Open
Abstract
The cell cycle is a collection of events by which cellular components such as genetic materials and cytoplasmic components are accurately divided into two daughter cells. The cell cycle transition is primarily driven by the activation of cyclin-dependent kinases (CDKs), which activities are regulated by the ubiquitin-mediated proteolysis of key regulators such as cyclins, CDK inhibitors (CKIs), other kinases and phosphatases. Thus, the ubiquitin-proteasome system (UPS) plays a pivotal role in the regulation of the cell cycle progression via recognition, interaction, and ubiquitination or deubiquitination of key proteins. The illegitimate degradation of tumor suppressor or abnormally high accumulation of oncoproteins often results in deregulation of cell proliferation, genomic instability, and cancer occurrence. In this review, we demonstrate the diversity and complexity of the regulation of UPS machinery of the cell cycle. A profound understanding of the ubiquitination machinery will provide new insights into the regulation of the cell cycle transition, cancer treatment, and the development of anti-cancer drugs.
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7
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Fan Y, Köberlin MS, Ratnayeke N, Liu C, Deshpande M, Gerhardt J, Meyer T. LRR1-mediated replisome disassembly promotes DNA replication by recycling replisome components. J Cell Biol 2021; 220:212186. [PMID: 34037657 PMCID: PMC8160578 DOI: 10.1083/jcb.202009147] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Revised: 03/30/2021] [Accepted: 05/04/2021] [Indexed: 11/22/2022] Open
Abstract
After two converging DNA replication forks meet, active replisomes are disassembled and unloaded from chromatin. A key process in replisome disassembly is the unloading of CMG helicases (CDC45–MCM–GINS), which is initiated in Caenorhabditis elegans and Xenopus laevis by the E3 ubiquitin ligase CRL2LRR1. Here, we show that human cells lacking LRR1 fail to unload CMG helicases and accumulate increasing amounts of chromatin-bound replisome components as cells progress through S phase. Markedly, we demonstrate that the failure to disassemble replisomes reduces the rate of DNA replication increasingly throughout S phase by sequestering rate-limiting replisome components on chromatin and blocking their recycling. Continued binding of CMG helicases to chromatin during G2 phase blocks mitosis by activating an ATR-mediated G2/M checkpoint. Finally, we provide evidence that LRR1 is an essential gene for human cell division, suggesting that CRL2LRR1 enzyme activity is required for the proliferation of cancer cells and is thus a potential target for cancer therapy.
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Affiliation(s)
- Yilin Fan
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA.,Department of Cell and Developmental Biology, Weill Cornell Medicine, New York, NY
| | - Marielle S Köberlin
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA
| | - Nalin Ratnayeke
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA.,Department of Cell and Developmental Biology, Weill Cornell Medicine, New York, NY
| | - Chad Liu
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA
| | - Madhura Deshpande
- Ronald O. Perelman and Claudia Cohen Center for Reproductive Medicine, Weill Cornell Medicine, New York, NY
| | - Jeannine Gerhardt
- Ronald O. Perelman and Claudia Cohen Center for Reproductive Medicine, Weill Cornell Medicine, New York, NY.,Department of Obstetrics and Gynecology, Weill Cornell Medicine, New York, NY
| | - Tobias Meyer
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA.,Department of Cell and Developmental Biology, Weill Cornell Medicine, New York, NY
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8
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Villa F, Fujisawa R, Ainsworth J, Nishimura K, Lie‐A‐Ling M, Lacaud G, Labib KPM. CUL2 LRR1 , TRAIP and p97 control CMG helicase disassembly in the mammalian cell cycle. EMBO Rep 2021; 22:e52164. [PMID: 33590678 PMCID: PMC7926238 DOI: 10.15252/embr.202052164] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Revised: 12/16/2020] [Accepted: 01/07/2021] [Indexed: 11/26/2022] Open
Abstract
The eukaryotic replisome is disassembled in each cell cycle, dependent upon ubiquitylation of the CMG helicase. Studies of Saccharomyces cerevisiae, Caenorhabditis elegans and Xenopus laevis have revealed surprising evolutionary diversity in the ubiquitin ligases that control CMG ubiquitylation, but regulated disassembly of the mammalian replisome has yet to be explored. Here, we describe a model system for studying the ubiquitylation and chromatin extraction of the mammalian CMG replisome, based on mouse embryonic stem cells. We show that the ubiquitin ligase CUL2LRR1 is required for ubiquitylation of the CMG-MCM7 subunit during S-phase, leading to disassembly by the p97 ATPase. Moreover, a second pathway of CMG disassembly is activated during mitosis, dependent upon the TRAIP ubiquitin ligase that is mutated in primordial dwarfism and mis-regulated in various cancers. These findings indicate that replisome disassembly in diverse metazoa is regulated by a conserved pair of ubiquitin ligases, distinct from those present in other eukaryotes.
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Affiliation(s)
- Fabrizio Villa
- The MRC Protein Phosphorylation and Ubiquitylation UnitSchool of Life SciencesUniversity of DundeeDundeeUK
| | - Ryo Fujisawa
- The MRC Protein Phosphorylation and Ubiquitylation UnitSchool of Life SciencesUniversity of DundeeDundeeUK
| | - Johanna Ainsworth
- The MRC Protein Phosphorylation and Ubiquitylation UnitSchool of Life SciencesUniversity of DundeeDundeeUK
| | - Kohei Nishimura
- The MRC Protein Phosphorylation and Ubiquitylation UnitSchool of Life SciencesUniversity of DundeeDundeeUK
- Division of Biological ScienceGraduate School of ScienceNagoya UniversityNagoyaJapan
| | - Michael Lie‐A‐Ling
- Cancer Research U.K. Manchester InstituteThe University of ManchesterAlderley ParkUK
| | - Georges Lacaud
- Cancer Research U.K. Manchester InstituteThe University of ManchesterAlderley ParkUK
| | - Karim PM Labib
- The MRC Protein Phosphorylation and Ubiquitylation UnitSchool of Life SciencesUniversity of DundeeDundeeUK
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9
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Song Q, Feng S, Peng W, Li A, Ma T, Yu B, Liu HM. Cullin-RING Ligases as Promising Targets for Gastric Carcinoma Treatment. Pharmacol Res 2021; 170:105493. [PMID: 33600940 DOI: 10.1016/j.phrs.2021.105493] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 02/07/2021] [Accepted: 02/11/2021] [Indexed: 12/14/2022]
Abstract
Gastric carcinoma has serious morbidity and mortality, which seriously threats human health. The studies on gastrointestinal cell biology have shown that the ubiquitination modification that occurs after protein translation plays an essential role in the pathogenesis of gastric carcinoma. Protein ubiquitination is catalyzed by E3 ubiquitin ligase and can regulate various substrate proteins in different cellular pathways. Cullin-RING E3 ligase (CRLs) is a representative of the E3 ubiquitin ligase family, which requires cullin (CUL) neddylation modification for activation to regulate homeostasis of ~20% of cellular proteins. The substrate molecules regulated by CRLs are often involved in many cell progressions such as cell cycle progression, cell apoptosis, DNA damage and repair. Given that CRLs play an important role in modulation of biological activities, so targeting a certain CULs member neddylation may be an attractive strategy for selectively controlling the cellular proteins levels to achieve the goal of cancer treatment. In this review, we will discuss the roles of CULs and Ring protein in gastric carcinoma and summarize the current neddylation modulators for gastric carcinoma treatment.
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Affiliation(s)
- Qianqian Song
- School of Pharmaceutical Sciences, Key Laboratory of Advanced Drug Preparation Technologies, Ministry of Education, Zhengzhou University, Zhengzhou 450001, PR China
| | - Siqi Feng
- School of Pharmaceutical Sciences, Key Laboratory of Advanced Drug Preparation Technologies, Ministry of Education, Zhengzhou University, Zhengzhou 450001, PR China
| | - Wenjun Peng
- School of Pharmaceutical Sciences, Key Laboratory of Advanced Drug Preparation Technologies, Ministry of Education, Zhengzhou University, Zhengzhou 450001, PR China
| | - Anqi Li
- School of Pharmaceutical Sciences, Key Laboratory of Advanced Drug Preparation Technologies, Ministry of Education, Zhengzhou University, Zhengzhou 450001, PR China
| | - Ting Ma
- School of Pharmaceutical Sciences, Key Laboratory of Advanced Drug Preparation Technologies, Ministry of Education, Zhengzhou University, Zhengzhou 450001, PR China; State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing 210009, PR China.
| | - Bin Yu
- School of Pharmaceutical Sciences, Key Laboratory of Advanced Drug Preparation Technologies, Ministry of Education, Zhengzhou University, Zhengzhou 450001, PR China; State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing 210009, PR China.
| | - Hong-Min Liu
- School of Pharmaceutical Sciences, Key Laboratory of Advanced Drug Preparation Technologies, Ministry of Education, Zhengzhou University, Zhengzhou 450001, PR China.
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10
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Vieyra-Garcia PA, Wolf P. A deep dive into UV-based phototherapy: Mechanisms of action and emerging molecular targets in inflammation and cancer. Pharmacol Ther 2020; 222:107784. [PMID: 33316286 DOI: 10.1016/j.pharmthera.2020.107784] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Accepted: 11/25/2020] [Indexed: 02/07/2023]
Abstract
UV-based phototherapy (including psoralen plus UVA (PUVA), UVB and UVA1) has a long, successful history in the management of numerous cutaneous disorders. Photoresponsive diseases are etiologically diverse, but most involve disturbances in local (and occasionally systemic) inflammatory cells and/or abnormalities in keratinocytes that trigger inflammation. UV-based phototherapy works by regulating the inflammatory component and inducing apoptosis of pathogenic cells. This results in a fascinating and complex network of simultaneous events-immediate transcriptional changes in keratinocytes, immune cells, and pigment cells; the emergence of apoptotic bodies; and the trafficking of antigen-presenting cells in skin-that quickly transform the microenvironment of UV-exposed skin. Molecular elements in this system of UV recognition and response include chromophores, metabolic byproducts, innate immune receptors, neurotransmitters and mediators such as chemokines and cytokines, antimicrobial peptides, and platelet activating factor (PAF) and PAF-like molecules that simultaneously shape the immunomodulatory effects of UV and their interplay with the microbiota of the skin and beyond. Phototherapy's key effects-proapoptotic, immunomodulatory, antipruritic, antifibrotic, propigmentary, and pro-prebiotic-promote clinical improvement in various skin diseases such as psoriasis, atopic dermatitis (AD), graft-versus-host disease (GvHD), vitiligo, scleroderma, and cutaneous T-cell lymphoma (CTCL) as well as prevention of polymorphic light eruption (PLE). As understanding of phototherapy improves, new therapies (UV- and non-UV-based) are being developed that will modify regulatory T-cells (Treg), interact with (resident) memory T-cells and /or utilize agonists and antagonists as well as antibodies targeting soluble molecules such as cytokines and chemokines, transcription factors, and a variety of membrane-associated receptors.
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Affiliation(s)
- Pablo A Vieyra-Garcia
- Department of Dermatology, Medical University of Graz, Auenbruggerplatz 8, Graz A-8036, Austria.
| | - Peter Wolf
- Department of Dermatology, Medical University of Graz, Auenbruggerplatz 8, Graz A-8036, Austria.
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11
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Jang SM, Redon CE, Thakur BL, Bahta MK, Aladjem MI. Regulation of cell cycle drivers by Cullin-RING ubiquitin ligases. Exp Mol Med 2020; 52:1637-1651. [PMID: 33005013 PMCID: PMC8080560 DOI: 10.1038/s12276-020-00508-4] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Accepted: 08/10/2020] [Indexed: 12/11/2022] Open
Abstract
The last decade has revealed new roles for Cullin-RING ubiquitin ligases (CRLs) in a myriad of cellular processes, including cell cycle progression. In addition to CRL1, also named SCF (SKP1-Cullin 1-F box protein), which has been known for decades as an important factor in the regulation of the cell cycle, it is now evident that all eight CRL family members are involved in the intricate cellular pathways driving cell cycle progression. In this review, we summarize the structure of CRLs and their functions in driving the cell cycle. We focus on how CRLs target key proteins for degradation or otherwise alter their functions to control the progression over the various cell cycle phases leading to cell division. We also summarize how CRLs and the anaphase-promoting complex/cyclosome (APC/C) ligase complex closely cooperate to govern efficient cell cycle progression.
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Affiliation(s)
- Sang-Min Jang
- Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD, 20892-4255, USA.
| | - Christophe E Redon
- Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD, 20892-4255, USA
| | - Bhushan L Thakur
- Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD, 20892-4255, USA
| | - Meriam K Bahta
- Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD, 20892-4255, USA
| | - Mirit I Aladjem
- Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD, 20892-4255, USA.
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12
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Liu X, Zurlo G, Zhang Q. The Roles of Cullin-2 E3 Ubiquitin Ligase Complex in Cancer. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1217:173-186. [PMID: 31898228 DOI: 10.1007/978-981-15-1025-0_11] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Posttranslational protein modifications play an important role in regulating protein stability and cellular function. There are at least eight Cullin family members. Among them, Cullin-2 forms a functional E3 ligase complex with elongin B, elongin C, RING-box protein 1 (RBX1, also called ROC1), as well as the substrate recognition subunit (SRS) to promote the substrate ubiquitination and degradation. In this book chapter, we will review Cullin-2 E3 ligase complexes that include various SRS proteins, including von Hippel Lindau (pVHL), leucine-rich repeat protein-1 (LRR-1), preferentially expressed antigen of melanoma (PRAME), sex-determining protein FEM-1 and early embryogenesis protein ZYG-11. We will focus on the VHL signaling pathway in clear cell renal cell carcinoma (ccRCC), which may reveal various therapeutic avenues in treating this lethal cancer.
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Affiliation(s)
- Xijuan Liu
- Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, NC, USA
| | - Giada Zurlo
- Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, NC, USA.,Department of Pathology, UT Southwestern Medical Center, Dallas, TX, USA
| | - Qing Zhang
- Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, NC, USA. .,Department of Pharmacology, University of North Carolina, Chapel Hill, NC, USA. .,Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, NC, USA. .,Department of Pathology, UT Southwestern Medical Center, Dallas, TX, USA.
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13
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Nazarie FW, Shih B, Angus T, Barnett MW, Chen SH, Summers KM, Klein K, Faulkner GJ, Saini HK, Watson M, Dongen SV, Enright AJ, Freeman TC. Visualization and analysis of RNA-Seq assembly graphs. Nucleic Acids Res 2019; 47:7262-7275. [PMID: 31305886 PMCID: PMC6698738 DOI: 10.1093/nar/gkz599] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Revised: 05/31/2019] [Accepted: 07/10/2019] [Indexed: 01/20/2023] Open
Abstract
RNA-Seq is a powerful transcriptome profiling technology enabling transcript discovery and quantification. Whilst most commonly used for gene-level quantification, the data can be used for the analysis of transcript isoforms. However, when the underlying transcript assemblies are complex, current visualization approaches can be limiting, with splicing events a challenge to interpret. Here, we report on the development of a graph-based visualization method as a complementary approach to understanding transcript diversity from short-read RNA-Seq data. Following the mapping of reads to a reference genome, a read-to-read comparison is performed on all reads mapping to a given gene, producing a weighted similarity matrix between reads. This is used to produce an RNA assembly graph, where nodes represent reads and edges similarity scores between them. The resulting graphs are visualized in 3D space to better appreciate their sometimes large and complex topology, with other information being overlaid on to nodes, e.g. transcript models. Here we demonstrate the utility of this approach, including the unusual structure of these graphs and how they can be used to identify issues in assembly, repetitive sequences within transcripts and splice variants. We believe this approach has the potential to significantly improve our understanding of transcript complexity.
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Affiliation(s)
- Fahmi W Nazarie
- Systems Immunology Group, The Roslin Institute and Royal (Dick) School of Veterinary Studies, The University of Edinburgh, Edinburgh EH25 9RG, UK
| | - Barbara Shih
- Systems Immunology Group, The Roslin Institute and Royal (Dick) School of Veterinary Studies, The University of Edinburgh, Edinburgh EH25 9RG, UK
| | - Tim Angus
- Systems Immunology Group, The Roslin Institute and Royal (Dick) School of Veterinary Studies, The University of Edinburgh, Edinburgh EH25 9RG, UK
| | - Mark W Barnett
- Systems Immunology Group, The Roslin Institute and Royal (Dick) School of Veterinary Studies, The University of Edinburgh, Edinburgh EH25 9RG, UK
| | - Sz-Hau Chen
- Systems Immunology Group, The Roslin Institute and Royal (Dick) School of Veterinary Studies, The University of Edinburgh, Edinburgh EH25 9RG, UK
| | - Kim M Summers
- Genetics and Genomics, The Roslin Institute and Royal (Dick) School of Veterinary Studies, The University of Edinburgh, Edinburgh EH25 9RG, UK.,Mater Research Institute - The University of Queensland, Translational Research Institute, 37 Kent St, Woolloongabba QLD 4102, Australia
| | - Karsten Klein
- Life Science Informatics Group, Department of Computer Science, Konstanz University, 78457 Konstanz, Germany
| | - Geoffrey J Faulkner
- Mater Research Institute - The University of Queensland, Translational Research Institute, 37 Kent St, Woolloongabba QLD 4102, Australia
| | - Harpreet K Saini
- Astex Pharmaceuticals, 436 Cambridge Science Park, Cambridge CB4 0QA, UK
| | - Mick Watson
- Genetics and Genomics, The Roslin Institute and Royal (Dick) School of Veterinary Studies, The University of Edinburgh, Edinburgh EH25 9RG, UK
| | - Stijn van Dongen
- Cellular Genetics Informatics, Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, CB10 1SA UK
| | - Anton J Enright
- Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK
| | - Tom C Freeman
- Systems Immunology Group, The Roslin Institute and Royal (Dick) School of Veterinary Studies, The University of Edinburgh, Edinburgh EH25 9RG, UK
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14
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Wang X, Rusin A, Walkey CJ, Lin JJ, Johnson DL. The RNA polymerase III repressor MAF1 is regulated by ubiquitin-dependent proteasome degradation and modulates cancer drug resistance and apoptosis. J Biol Chem 2019; 294:19255-19268. [PMID: 31645432 DOI: 10.1074/jbc.ra119.008849] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Revised: 10/01/2019] [Indexed: 01/03/2023] Open
Abstract
MAF1 homolog, negative regulator of RNA polymerase III (MAF1) is a key repressor of RNA polymerase (pol) III-dependent transcription and functions as a tumor suppressor. Its expression is frequently down-regulated in primary human hepatocellular carcinomas (HCCs). However, this reduction in MAF1 protein levels does not correlate with its transcript levels, indicating that MAF1 is regulated post-transcriptionally. Here, we demonstrate that MAF1 is a labile protein whose levels are regulated through the ubiquitin-dependent proteasome pathway. We found that MAF1 ubiquitination is enhanced upon mTOR complex 1 (TORC1)-mediated phosphorylation at Ser-75. Moreover, we observed that the E3 ubiquitin ligase cullin 2 (CUL2) critically regulates MAF1 ubiquitination and controls its stability and subsequent RNA pol III-dependent transcription. Analysis of the phenotypic consequences of modulating either CUL2 or MAF1 protein expression revealed changes in actin cytoskeleton reorganization and altered sensitivity to doxorubicin-induced apoptosis. Repression of RNA pol III-dependent transcription by chemical inhibition or knockdown of BRF1 RNA pol III transcription initiation factor subunit (BRF1) enhanced HCC cell sensitivity to doxorubicin, suggesting that MAF1 regulates doxorubicin resistance in HCC by controlling RNA pol III-dependent transcription. Together, our results identify the ubiquitin proteasome pathway and CUL2 as important regulators of MAF1 levels. They suggest that decreases in MAF1 protein underlie chemoresistance in HCC and perhaps other cancers and point to an important role for MAF1 and RNA pol III-mediated transcription in chemosensitivity and apoptosis.
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Affiliation(s)
- Xianlong Wang
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas 77030
| | - Aleksandra Rusin
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas 77030
| | - Christopher J Walkey
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas 77030
| | | | - Deborah L Johnson
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas 77030
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15
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Kreis NN, Louwen F, Yuan J. The Multifaceted p21 (Cip1/Waf1/ CDKN1A) in Cell Differentiation, Migration and Cancer Therapy. Cancers (Basel) 2019; 11:cancers11091220. [PMID: 31438587 PMCID: PMC6770903 DOI: 10.3390/cancers11091220] [Citation(s) in RCA: 154] [Impact Index Per Article: 30.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Revised: 08/15/2019] [Accepted: 08/17/2019] [Indexed: 12/12/2022] Open
Abstract
Loss of cell cycle control is characteristic of tumorigenesis. The protein p21 is the founding member of cyclin-dependent kinase inhibitors and an important versatile cell cycle protein. p21 is transcriptionally controlled by p53 and p53-independent pathways. Its expression is increased in response to various intra- and extracellular stimuli to arrest the cell cycle ensuring genomic stability. Apart from its roles in cell cycle regulation including mitosis, p21 is involved in differentiation, cell migration, cytoskeletal dynamics, apoptosis, transcription, DNA repair, reprogramming of induced pluripotent stem cells, autophagy and the onset of senescence. p21 acts either as a tumor suppressor or as an oncogene depending largely on the cellular context, its subcellular localization and posttranslational modifications. In the present review, we briefly mention the general functions of p21 and summarize its roles in differentiation, migration and invasion in detail. Finally, regarding its dual role as tumor suppressor and oncogene, we highlight the potential, difficulties and risks of using p21 as a biomarker as well as a therapeutic target.
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Affiliation(s)
- Nina-Naomi Kreis
- Department of Gynecology and Obstetrics, University Hospital, J. W. Goethe-University, Theodor-Stern-Kai 7, D-60590 Frankfurt, Germany.
| | - Frank Louwen
- Department of Gynecology and Obstetrics, University Hospital, J. W. Goethe-University, Theodor-Stern-Kai 7, D-60590 Frankfurt, Germany
| | - Juping Yuan
- Department of Gynecology and Obstetrics, University Hospital, J. W. Goethe-University, Theodor-Stern-Kai 7, D-60590 Frankfurt, Germany
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16
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Developmental Control of the Cell Cycle: Insights from Caenorhabditis elegans. Genetics 2019; 211:797-829. [PMID: 30846544 PMCID: PMC6404260 DOI: 10.1534/genetics.118.301643] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2018] [Accepted: 10/10/2018] [Indexed: 12/11/2022] Open
Abstract
During animal development, a single fertilized egg forms a complete organism with tens to trillions of cells that encompass a large variety of cell types. Cell cycle regulation is therefore at the center of development and needs to be carried out in close coordination with cell differentiation, migration, and death, as well as tissue formation, morphogenesis, and homeostasis. The timing and frequency of cell divisions are controlled by complex combinations of external and cell-intrinsic signals that vary throughout development. Insight into how such controls determine in vivo cell division patterns has come from studies in various genetic model systems. The nematode Caenorhabditis elegans has only about 1000 somatic cells and approximately twice as many germ cells in the adult hermaphrodite. Despite the relatively small number of cells, C. elegans has diverse tissues, including intestine, nerves, striated and smooth muscle, and skin. C. elegans is unique as a model organism for studies of the cell cycle because the somatic cell lineage is invariant. Somatic cells divide at set times during development to produce daughter cells that adopt reproducible developmental fates. Studies in C. elegans have allowed the identification of conserved cell cycle regulators and provided insights into how cell cycle regulation varies between tissues. In this review, we focus on the regulation of the cell cycle in the context of C. elegans development, with reference to other systems, with the goal of better understanding how cell cycle regulation is linked to animal development in general.
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17
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Chen T, Huang H, Zhou Y, Geng L, Shen T, Yin S, Zhou L, Zheng S. HJURP promotes hepatocellular carcinoma proliferation by destabilizing p21 via the MAPK/ERK1/2 and AKT/GSK3β signaling pathways. J Exp Clin Cancer Res 2018; 37:193. [PMID: 30111352 PMCID: PMC6094877 DOI: 10.1186/s13046-018-0866-4] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Accepted: 08/06/2018] [Indexed: 12/04/2022] Open
Abstract
BACKGROUND Holliday junction recognition protein (HJURP) has been implicated in many cancers including hepatocellular carcinoma (HCC). However, the underlying mechanism by which HJURP promotes HCC cell proliferation remains unclear. METHODS RT-qPCR and immunohistochemistry were used to detect HJURP expression in HCC and adjacent tumor tissues and HCC cell lines. The localization of p21 were determined by immunofluorescence and western blot. Co-immunoprecipitation and western blot were used to validate the p21 stability and signaling pathways affected by HJURP. The effects of HJURP on HCC cell proliferation were assessed both in vivo and in vitro. The ERK1/2 pathway inhibitor U0126 and AKT pathway agonist SC-79 were used to treat HCC cell lines for further mechanistic investigations. RESULTS HJURP expression was higher in HCC tissues than in para-tumor tissues. Moreover, ectopic HJURP expression facilitated the proliferation of HCC cells, whereas the depletion of HJURP resulted in decreased cell growth in vitro and in vivo. Furthermore, the effects of HJURP silencing were reversed by p21 knockdown. Likewise, p21 overexpression inhibited cell growth ability mediated by HJURP elevation. Mechanistically, HJURP destabilized p21 via the MAPK/ERK1/2 and AKT/GSK3β pathways, which regulated the nucleus-cytoplasm translocation and ubiquitin-mediated degradation of p21. Clinically, high HJURP expression was correlated with unfavorable prognoses in HCC individuals. CONCLUSIONS Our data revealed that HJURP is an oncogene that drives cell cycle progression upstream of p21 in HCC. These findings may provide a potential therapeutic and prognostic target for HCC.
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Affiliation(s)
- Tianchi Chen
- Division of Hepatobiliary and Pancreatic Surgery, Department of Surgery, First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
- Key Laboratory of Combined Multi-organ Transplantation, Ministry of Public Health, Hangzhou, China
- Key Laboratory of Organ Transplantation, Zhejiang Province, Hangzhou, China
- Key Laboratory of the diagnosis and treatment of organ Transplantation, CAMS, Hangzhou, China
- Collaborative Innovation Center for Diagnosis Treatment of Infectious Diseases, Zhejiang University, Hangzhou, China
| | - Hechen Huang
- Division of Hepatobiliary and Pancreatic Surgery, Department of Surgery, First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
- Key Laboratory of Combined Multi-organ Transplantation, Ministry of Public Health, Hangzhou, China
- Key Laboratory of Organ Transplantation, Zhejiang Province, Hangzhou, China
- Key Laboratory of the diagnosis and treatment of organ Transplantation, CAMS, Hangzhou, China
- Collaborative Innovation Center for Diagnosis Treatment of Infectious Diseases, Zhejiang University, Hangzhou, China
| | - Yuan Zhou
- Division of Hepatobiliary and Pancreatic Surgery, Department of Surgery, First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
- Key Laboratory of Combined Multi-organ Transplantation, Ministry of Public Health, Hangzhou, China
- Key Laboratory of Organ Transplantation, Zhejiang Province, Hangzhou, China
- Key Laboratory of the diagnosis and treatment of organ Transplantation, CAMS, Hangzhou, China
- Collaborative Innovation Center for Diagnosis Treatment of Infectious Diseases, Zhejiang University, Hangzhou, China
| | - Lei Geng
- Division of Hepatobiliary and Pancreatic Surgery, Department of Surgery, First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Tian Shen
- Division of Hepatobiliary and Pancreatic Surgery, Department of Surgery, First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Shengyong Yin
- Key Laboratory of Combined Multi-organ Transplantation, Ministry of Public Health, Hangzhou, China
- Key Laboratory of Organ Transplantation, Zhejiang Province, Hangzhou, China
- Key Laboratory of the diagnosis and treatment of organ Transplantation, CAMS, Hangzhou, China
| | - Lin Zhou
- Key Laboratory of Combined Multi-organ Transplantation, Ministry of Public Health, Hangzhou, China
- Key Laboratory of Organ Transplantation, Zhejiang Province, Hangzhou, China
- Key Laboratory of the diagnosis and treatment of organ Transplantation, CAMS, Hangzhou, China
- Collaborative Innovation Center for Diagnosis Treatment of Infectious Diseases, Zhejiang University, Hangzhou, China
| | - Shusen Zheng
- Division of Hepatobiliary and Pancreatic Surgery, Department of Surgery, First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
- Key Laboratory of Combined Multi-organ Transplantation, Ministry of Public Health, Hangzhou, China
- Key Laboratory of Organ Transplantation, Zhejiang Province, Hangzhou, China
- Key Laboratory of the diagnosis and treatment of organ Transplantation, CAMS, Hangzhou, China
- Collaborative Innovation Center for Diagnosis Treatment of Infectious Diseases, Zhejiang University, Hangzhou, China
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18
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Jang SM, Redon CE, Aladjem MI. Chromatin-Bound Cullin-Ring Ligases: Regulatory Roles in DNA Replication and Potential Targeting for Cancer Therapy. Front Mol Biosci 2018; 5:19. [PMID: 29594129 PMCID: PMC5859106 DOI: 10.3389/fmolb.2018.00019] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Accepted: 02/12/2018] [Indexed: 12/14/2022] Open
Abstract
Cullin-RING (Really Interesting New Gene) E3 ubiquitin ligases (CRLs), the largest family of E3 ubiquitin ligases, are functional multi-subunit complexes including substrate receptors, adaptors, cullin scaffolds, and RING-box proteins. CRLs are responsible for ubiquitination of ~20% of cellular proteins and are involved in diverse biological processes including cell cycle progression, genome stability, and oncogenesis. Not surprisingly, cullins are deregulated in many diseases and instances of cancer. Recent studies have highlighted the importance of CRL-mediated ubiquitination in the regulation of DNA replication/repair, including specific roles in chromatin assembly and disassembly of the replication machinery. The development of novel therapeutics targeting the CRLs that regulate the replication machinery and chromatin in cancer is now an attractive therapeutic strategy. In this review, we summarize the structure and assembly of CRLs and outline their cellular functions and their diverse roles in cancer, emphasizing the regulatory functions of nuclear CRLs in modulating the DNA replication machinery. Finally, we discuss the current strategies for targeting CRLs against cancer in the clinic.
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Affiliation(s)
| | | | - Mirit I. Aladjem
- Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD, United States
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19
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Wang S, Xia W, Qiu M, Wang X, Jiang F, Yin R, Xu L. Atlas on substrate recognition subunits of CRL2 E3 ligases. Oncotarget 2018; 7:46707-46716. [PMID: 27107416 PMCID: PMC5216831 DOI: 10.18632/oncotarget.8732] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Accepted: 04/02/2016] [Indexed: 12/16/2022] Open
Abstract
The Cullin2-type ubiquitin ligases belong to the Cullin-Ring Ligase (CRL) family, which is a crucial determinant of proteasome-based degradation processes in eukaryotes. Because of the finding of von Hippel-Lindau tumor suppressor (VHL), the Cullin2-type ubiquitin ligases gain focusing in the research of many diseases, especially in tumors. These multisubunit enzymes are composed of the Ring finger protein, the Cullin2 scaffold protein, the Elongin B&C linker protein and the variant substrate recognition subunits (SRSs), among which the Cullin2 scaffold protein is the determining factor of the enzyme mechanism. Substrate recognition of Cullin2-type ubiquitin ligases depends on SRSs and results in the degradation of diseases associated substrates by intracellular signaling events. This review focuses on the diversity and the multifunctionality of SRSs in the Cullin2-type ubiquitin ligases, including VHL, LRR-1, FEM1b, PRAME and ZYG11. Recently, as more SRSs are being discovered and more aspects of substrate recognition have been illuminated, insight into the relationship between Cul2-dependent SRSs and substrates provides a new area for cancer research.
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Affiliation(s)
- Siwei Wang
- Department of Thoracic Surgery, Nanjing Medical University Affiliated Cancer Hospital, Jiangsu Key Laboratory of Molecular and Translational Cancer Research, Cancer Institute of Jiangsu Province, Nanjing, China.,The Fourth Clinical College of Nanjing Medical University, Nanjing, China
| | - Wenjia Xia
- Department of Thoracic Surgery, Nanjing Medical University Affiliated Cancer Hospital, Jiangsu Key Laboratory of Molecular and Translational Cancer Research, Cancer Institute of Jiangsu Province, Nanjing, China.,The Fourth Clinical College of Nanjing Medical University, Nanjing, China
| | - Mantang Qiu
- Department of Thoracic Surgery, Nanjing Medical University Affiliated Cancer Hospital, Jiangsu Key Laboratory of Molecular and Translational Cancer Research, Cancer Institute of Jiangsu Province, Nanjing, China.,The Fourth Clinical College of Nanjing Medical University, Nanjing, China
| | - Xin Wang
- Department of Thoracic Surgery, Nanjing Medical University Affiliated Cancer Hospital, Jiangsu Key Laboratory of Molecular and Translational Cancer Research, Cancer Institute of Jiangsu Province, Nanjing, China.,The Fourth Clinical College of Nanjing Medical University, Nanjing, China
| | - Feng Jiang
- Department of Thoracic Surgery, Nanjing Medical University Affiliated Cancer Hospital, Jiangsu Key Laboratory of Molecular and Translational Cancer Research, Cancer Institute of Jiangsu Province, Nanjing, China
| | - Rong Yin
- Department of Thoracic Surgery, Nanjing Medical University Affiliated Cancer Hospital, Jiangsu Key Laboratory of Molecular and Translational Cancer Research, Cancer Institute of Jiangsu Province, Nanjing, China
| | - Lin Xu
- Department of Thoracic Surgery, Nanjing Medical University Affiliated Cancer Hospital, Jiangsu Key Laboratory of Molecular and Translational Cancer Research, Cancer Institute of Jiangsu Province, Nanjing, China
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20
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21
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Sonneville R, Moreno SP, Knebel A, Johnson C, Hastie CJ, Gartner A, Gambus A, Labib K. CUL-2 LRR-1 and UBXN-3 drive replisome disassembly during DNA replication termination and mitosis. Nat Cell Biol 2017; 19:468-479. [PMID: 28368371 PMCID: PMC5410169 DOI: 10.1038/ncb3500] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Accepted: 02/27/2017] [Indexed: 02/06/2023]
Abstract
Replisome disassembly is the final step of DNA replication in eukaryotes, involving the ubiquitylation and CDC48-dependent dissolution of the CMG helicase (CDC45-MCM-GINS). Using Caenorhabditis elegans early embryos and Xenopus laevis egg extracts, we show that the E3 ligase CUL-2LRR-1 associates with the replisome and drives ubiquitylation and disassembly of CMG, together with the CDC-48 cofactors UFD-1 and NPL-4. Removal of CMG from chromatin in frog egg extracts requires CUL2 neddylation, and our data identify chromatin recruitment of CUL2LRR1 as a key regulated step during DNA replication termination. Interestingly, however, CMG persists on chromatin until prophase in worms that lack CUL-2LRR-1, but is then removed by a mitotic pathway that requires the CDC-48 cofactor UBXN-3, orthologous to the human tumour suppressor FAF1. Partial inactivation of lrr-1 and ubxn-3 leads to synthetic lethality, suggesting future approaches by which a deeper understanding of CMG disassembly in metazoa could be exploited therapeutically.
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Affiliation(s)
- Remi Sonneville
- MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, UK
| | - Sara Priego Moreno
- Institute of Cancer and Genomic Sciences, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Axel Knebel
- MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, UK
| | - Clare Johnson
- MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, UK
| | - C James Hastie
- MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, UK
| | - Anton Gartner
- Centre for Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, UK
| | - Agnieszka Gambus
- Institute of Cancer and Genomic Sciences, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Karim Labib
- MRC Protein Phosphorylation and Ubiquitylation Unit, School of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, UK
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22
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Expression of SOCS1 and the downstream targets of its putative tumor suppressor functions in prostate cancer. BMC Cancer 2017; 17:157. [PMID: 28235401 PMCID: PMC5326496 DOI: 10.1186/s12885-017-3141-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Accepted: 02/15/2017] [Indexed: 01/28/2023] Open
Abstract
Background Suppressor of cytokine signaling 1 (SOCS1) is considered a tumor suppressor due to frequent epigenetic and micro-RNA-mediated repression of its gene expression in diverse cancers. In prostate cancer (PCa), elevated expression of miR-30d that targets SOCS1 mRNA is associated with increased risk of disease recurrence. SOCS1 can mediate its tumor suppressor functions by diverse mechanisms such as inhibiting the JAK-STAT signaling pathway, promoting the tumor suppressor functions of p53, attenuating MET receptor tyrosine kinase signaling and blocking the oncogenic potential of the cell cycle inhibitor p21CIP1 (p21). Here, we studied the expression of SOCS1 and the downstream targets of its putative tumor suppressor functions (p53, MET and p21) in human PCa specimens to evaluate their significance as markers of disease prognosis. Methods Tissue microarrays were constructed of 78 archived prostatectomy specimens that were grouped according to the recommendations of the International Society of Urological Pathology (ISUP) based on the Gleason patterns. SOCS1, p53, MET and p21 protein expression were evaluated by immunohistochemical staining alongside the common prostate cancer-related markers Ki67, prostein and androgen receptor. Statistical correlations between the staining intensities of these markers and ISUP grade groups, local invasion or lymph node metastasis were evaluated. Results SOCS1 showed diffuse staining in the prostatic epithelium. SOCS1 staining intensity correlated inversely with the ISUP grade groups (ρ = −0.4687, p <0.0001) and Ki67 (ρ = −0.2444, p = 0.031), and positively with prostein (ρ = 0.3511, p = 0.0016). Changes in SOCS1 levels did not significantly associate with those of p53, MET or p21. However, p21 positively correlated with androgen receptor expression (ρ = −0.1388, p = 0.0003). A subset of patients with regional lymph node metastasis, although small in number, showed reduced SOCS1 expression and increased expression of MET and p21. Conclusions Our findings suggest that evaluating SOCS1 and p21 protein expression in prostatectomy specimens may have a prognostic value in identifying the aggressive disease. Hence, prospective studies with larger numbers of metastatic PCa specimens incorporating clinical correlates such as disease-free and overall survival are warranted. Electronic supplementary material The online version of this article (doi:10.1186/s12885-017-3141-8) contains supplementary material, which is available to authorized users.
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Blondelle J, Shapiro P, Domenighetti AA, Lange S. Cullin E3 Ligase Activity Is Required for Myoblast Differentiation. J Mol Biol 2017; 429:1045-1066. [PMID: 28238764 DOI: 10.1016/j.jmb.2017.02.012] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Revised: 02/17/2017] [Accepted: 02/18/2017] [Indexed: 01/06/2023]
Abstract
The role of cullin E3-ubiquitin ligases for muscle homeostasis is best known during muscle atrophy, as the cullin-1 substrate adaptor atrogin-1 is among the most well-characterized muscle atrogins. We investigated whether cullin activity was also crucial during terminal myoblast differentiation and aggregation of acetylcholine receptors for the establishment of neuromuscular junctions in vitro. The activity of cullin E3-ligases is modulated through post-translational modification with the small ubiquitin-like modifier nedd8. Using either the Nae1 inhibitor MLN4924 (Pevonedistat) or siRNA against nedd8 in early or late stages of differentiation on C2C12 myoblasts, and primary satellite cells from mouse and human, we show that cullin E3-ligase activity is necessary for each step of the muscle cell differentiation program in vitro. We further investigate known transcriptional repressors for terminal muscle differentiation, namely ZBTB38, Bhlhe41, and Id1. Due to their identified roles for terminal muscle differentiation, we hypothesize that the accumulation of these potential cullin E3-ligase substrates may be partially responsible for the observed phenotype. MLN4924 is currently undergoing clinical trials in cancer patients, and our experiments highlight concerns on the homeostasis and regenerative capacity of muscles in these patients who often experience cachexia.
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Affiliation(s)
- Jordan Blondelle
- Division of Cardiology, University of California San Diego, La Jolla, CA-92093 USA
| | - Paige Shapiro
- Division of Cardiology, University of California San Diego, La Jolla, CA-92093 USA
| | - Andrea A Domenighetti
- Rehabilitation Institute of Chicago, Chicago, IL-60611 USA; Department of Physical Medicine and Rehabilitation, Northwestern University, Chicago, IL-60611, USA
| | - Stephan Lange
- Division of Cardiology, University of California San Diego, La Jolla, CA-92093 USA.
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24
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Damiani E, Puebla-Osorio N, Lege BM, Liu J, Neelapu SS, Ullrich SE. Platelet activating factor-induced expression of p21 is correlated with histone acetylation. Sci Rep 2017; 7:41959. [PMID: 28157211 PMCID: PMC5291204 DOI: 10.1038/srep41959] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Accepted: 12/30/2016] [Indexed: 02/07/2023] Open
Abstract
Ultraviolet (UV)-irradiated keratinocytes secrete the lipid mediator of inflammation, platelet-activating factor (PAF). PAF plays an essential role in UV-induced immune suppression and skin cancer induction. Dermal mast cell migration from the skin to the draining lymph nodes plays a prominent role in activating systemic immune suppression. UV-induced PAF activates mast cell migration by up-regulating mast cell CXCR4 surface expression. Recent findings indicate that PAF up-regulates CXCR4 expression via histone acetylation. UV-induced PAF also activates cell cycle arrest and disrupts DNA repair, in part by increasing p21 expression. Do epigenetic alterations play a role in p21 up-regulation? Here we show that PAF increases Acetyl-CREB-binding protein (CBP/p300) histone acetyltransferase expression in a time and dose-dependent fashion. Partial deletion of the HAT domain in the CBP gene, blocked these effects. Chromatin immunoprecipitation assays indicated that PAF-treatment activated the acetylation of the p21 promoter. PAF-treatment had no effect on other acetylating enzymes (GCN5L2, PCAF) indicating it is not a global activator of histone acetylation. This study provides further evidence that PAF activates epigenetic mechanisms to affect important cellular processes, and we suggest this bioactive lipid can serve as a link between the environment and the epigenome.
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Affiliation(s)
- Elisabetta Damiani
- Dipartimento di Scienze della Vita e dell'Ambiente, Universita' Politecnica delle Marche, Ancona, Italy
| | - Nahum Puebla-Osorio
- Department of Lymphoma and Myeloma, The University of Texas, MD Anderson Cancer Center, Houston, Texas, USA
| | - Bree M Lege
- Department of Lymphoma and Myeloma, The University of Texas, MD Anderson Cancer Center, Houston, Texas, USA
| | - Jingwei Liu
- Department of Lymphoma and Myeloma, The University of Texas, MD Anderson Cancer Center, Houston, Texas, USA
| | - Sattva S Neelapu
- Department of Lymphoma and Myeloma, The University of Texas, MD Anderson Cancer Center, Houston, Texas, USA
| | - Stephen E Ullrich
- Department of Immunology and The Center for Cancer Immunology Research, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA.,The University of Texas Graduate School for Biomedical Sciences at Houston, The University of Texas, MD Anderson Cancer Center, Houston, Texas, USA
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Zhao H, Lu Z, Bauzon F, Fu H, Cui J, Locker J, Zhu L. p27T187A knockin identifies Skp2/Cks1 pocket inhibitors for advanced prostate cancer. Oncogene 2017; 36:60-70. [PMID: 27181203 PMCID: PMC5112153 DOI: 10.1038/onc.2016.175] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Revised: 03/04/2016] [Accepted: 04/11/2016] [Indexed: 12/27/2022]
Abstract
SCFSkp2/Cks1 ubiquitinates Thr187-phosphorylated p27 for degradation. Overexpression of Skp2 coupled with underexpression of p27 are frequent characteristics of cancer cells. When the role of SCFSkp2/Cks1-mediated p27 ubiquitination in cancer was specifically tested by p27 Thr187-to-Ala knockin (p27T187A KI), it was found dispensable for KrasG12D-induced lung tumorigenesis but essential for Rb1-deficient pituitary tumorigenesis. Here we identify pRb and p53 doubly deficient (DKO) prostate tumorigenesis as a context in which p27 ubiquitination by SCFSkp2/Cks1 is required for p27 downregulation. p27 protein accumulated in prostate when p27T187A KI mice underwent DKO prostate tumorigenesis. p27T187A KI or Skp2 knockdown (KD) induced similar degrees of p27 protein accumulation in DKO prostate cells, and Skp2 KD did not further increase p27 protein in DKO prostate cells that contained p27T187A KI (AADKO prostate cells). p27T187A KI activated an E2F1-p73-apoptosis axis in DKO prostate tumorigenesis, slowed disease progression and significantly extended survival. Querying co-occurrence relationships among RB1, TP53, PTEN, NKX3-1 and MYC in TCGA of prostate cancer identified co-inactivation of RB1 and TP53 as the only statistically significant co-occurrences in metastatic castration-resistant prostate cancer (mCRPC). Together, our study identifies Skp2/Cks1 pocket inhibitors as potential therapeutics for mCRPC. Procedures for establishing mCRPC organoid cultures from contemporary patients were recently established. An Skp2/Cks1 pocket inhibitor preferentially collapsed DKO prostate tumor organoids over AADKO organoids, which spontaneously disintegrated over time when DKO prostate tumor organoids grew larger, setting the stage to translate mouse model findings to precision medicine in the clinic on the organoid platform.
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Affiliation(s)
- Hongling Zhao
- Department of Developmental and Molecular Biology, and Ophthalmology & Visual Sciences, and Medicine, The Albert Einstein Comprehensive Cancer Center and Liver Research Center, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Zhonglei Lu
- Department of Developmental and Molecular Biology, and Ophthalmology & Visual Sciences, and Medicine, The Albert Einstein Comprehensive Cancer Center and Liver Research Center, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Frederick Bauzon
- Department of Developmental and Molecular Biology, and Ophthalmology & Visual Sciences, and Medicine, The Albert Einstein Comprehensive Cancer Center and Liver Research Center, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Hao Fu
- Department of Developmental and Molecular Biology, and Ophthalmology & Visual Sciences, and Medicine, The Albert Einstein Comprehensive Cancer Center and Liver Research Center, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Jinhua Cui
- Department of Developmental and Molecular Biology, and Ophthalmology & Visual Sciences, and Medicine, The Albert Einstein Comprehensive Cancer Center and Liver Research Center, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Joseph Locker
- Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
| | - Liang Zhu
- Department of Developmental and Molecular Biology, and Ophthalmology & Visual Sciences, and Medicine, The Albert Einstein Comprehensive Cancer Center and Liver Research Center, Albert Einstein College of Medicine, Bronx, NY 10461, USA
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Gambus A. Termination of Eukaryotic Replication Forks. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 1042:163-187. [DOI: 10.1007/978-981-10-6955-0_8] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Regulation of the MEI-1/MEI-2 Microtubule-Severing Katanin Complex in Early Caenorhabditis elegans Development. G3-GENES GENOMES GENETICS 2016; 6:3257-3268. [PMID: 27527792 PMCID: PMC5068946 DOI: 10.1534/g3.116.031666] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
After fertilization, rapid changes of the Caenorhabditis elegans cytoskeleton occur in the transition from meiosis to mitosis, requiring precise regulation. The MEI-1/MEI-2 katanin microtubule-severing complex is essential for meiotic spindle formation but must be quickly inactivated to allow for proper formation of the mitotic spindle. MEI-1/MEI-2 inactivation is dependent on multiple redundant pathways. The primary pathway employs the MEL-26 substrate adaptor for the CUL-3/cullin-based E3 ubiquitin ligase, which targets MEI-1 for proteosomal degradation. Here, we used quantitative antibody staining to measure MEI-1 levels to determine how other genes implicated in MEI-1 regulation act relative to CUL-3/MEL-26. The anaphase-promoting complex/cyclosome, APC/C, the DYRK (Dual-specificity tyrosine-regulated kinase), MBK-2, and the CUL-2-based E3 ubiquitin ligase act together to degrade MEI-1, in parallel to MEL-26/CUL-3. CUL-2 is known to keep MEL-26 low during meiosis, so CUL-2 apparently changes its target from MEL-26 in meiosis to MEI-1 in mitosis. RFL-1, an activator of cullin E3 ubiquitin ligases, activates CUL-2 but not CUL-3 for MEI-1 elimination. HECD-1 (HECT/Homologous to the E6AP carboxyl terminus domain) E3 ligase acts as a MEI-1 activator in meiosis but functions as an inhibitor during mitosis, without affecting levels of MEI-1 or MEI-2. Our results highlight the multiple layers of MEI-1 regulation that are required during the switch from the meiotic to mitotic modes of cell division.
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SCFFbl12 Increases p21Waf1/Cip1 Expression Level through Atypical Ubiquitin Chain Synthesis. Mol Cell Biol 2016; 36:2182-94. [PMID: 27215384 DOI: 10.1128/mcb.00174-16] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Accepted: 05/17/2016] [Indexed: 11/20/2022] Open
Abstract
The cyclin-dependent kinase (CDK) inhibitor p21 is an unstructured protein regulated by multiple turnover pathways. p21 abundance is tightly regulated, and its defect causes tumor development. However, the mechanisms that underlie the control of p21 level are not fully understood. Here, we report a novel mechanism by which a component of the SCF ubiquitin ligase, Fbl12, augments p21 via the formation of atypical ubiquitin chains. We found that Fbl12 binds and ubiquitinates p21. Unexpectedly, Fbl12 increases the expression level of p21 by enhancing the mixed-type ubiquitination, including not only K48- but also K63-linked ubiquitin chains, followed by promotion of binding between p21 and CDK2. We also found that proteasome activator PA28γ attenuates p21 ubiquitination by interacting with Fbl12. In addition, UV irradiation induces a dissociation of p21 from Fbl12 and decreases K63-linked ubiquitination, leading to p21 degradation. These data suggest that Fbl12 is a key factor that maintains adequate intracellular concentration of p21 under normal conditions. Our finding may provide a novel possibility that p21's fate is governed by diverse ubiquitin chains.
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Cai W, Yang H. The structure and regulation of Cullin 2 based E3 ubiquitin ligases and their biological functions. Cell Div 2016; 11:7. [PMID: 27222660 PMCID: PMC4878042 DOI: 10.1186/s13008-016-0020-7] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Accepted: 05/11/2016] [Indexed: 11/23/2022] Open
Abstract
Background Cullin-RING E3 ubiquitin ligase complexes play a central role in targeting cellular proteins for ubiquitination-dependent protein turnover through 26S proteasome. Cullin-2 is a member of the Cullin family, and it serves as a scaffold protein for Elongin B and C, Rbx1 and various substrate recognition receptors to form E3 ubiquitin ligases. Main body of the abstract First, the composition, structure and the regulation of Cullin-2 based E3 ubiquitin ligases were introduced. Then the targets, the biological functions of complexes that use VHL, Lrr-1, Fem1b, Prame, Zyg-11, BAF250, Rack1 as substrate targeting subunits were described, and their involvement in diseases was discussed. A small molecule inhibitor of Cullins as a potential anti-cancer drug was introduced. Furthermore, proteins with VHL box that might bind to Cullin-2 were described. Finally, how different viral proteins form E3 ubiquitin ligase complexes with Cullin-2 to counter host viral defense were explained. Conclusions Cullin-2 based E3 ubiquitin ligases, using many different substrate recognition receptors, recognize a number of substrates and regulate their protein stability. These complexes play critical roles in biological processes and diseases such as cancer, germline differentiation and viral defense. Through the better understanding of their biology, we can devise and develop new therapeutic strategies to treat cancers, inherited diseases and viral infections.
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Affiliation(s)
- Weijia Cai
- Department of Pathology and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107 USA
| | - Haifeng Yang
- Department of Pathology and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107 USA
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Biology of the cell cycle inhibitor p21CDKN1A: molecular mechanisms and relevance in chemical toxicology. Arch Toxicol 2014; 89:155-78. [DOI: 10.1007/s00204-014-1430-4] [Citation(s) in RCA: 127] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Accepted: 12/03/2014] [Indexed: 02/07/2023]
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Moniot B, Ujjan S, Champagne J, Hirai H, Aritake K, Nagata K, Dubois E, Nidelet S, Nakamura M, Urade Y, Poulat F, Boizet-Bonhoure B. Prostaglandin D2 acts through the Dp2 receptor to influence male germ cell differentiation in the foetal mouse testis. Development 2014; 141:3561-71. [DOI: 10.1242/dev.103408] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Through intercellular signalling, the somatic compartment of the foetal testis is able to program primordial germ cells to undergo spermatogenesis. Fibroblast growth factor 9 and several members of the transforming growth factor β superfamily are involved in this process in the foetal testis, counteracting the induction of meiosis by retinoic acid and activating germinal mitotic arrest. Here, using in vitro and in vivo approaches, we show that prostaglandin D2 (PGD2), which is produced through both L-Pgds and H-Pgds enzymatic activities in the somatic and germ cell compartments of the foetal testis, plays a role in mitotic arrest in male germ cells by activating the expression and nuclear localization of the CDK inhibitor p21Cip1 and by repressing pluripotency markers. We show that PGD2 acts through its Dp2 receptor, at least in part through direct effects in germ cells, and contributes to the proper differentiation of male germ cells through the upregulation of the master gene Nanos2. Our data identify PGD2 signalling as an early pathway that acts in both paracrine and autocrine manners, and contributes to the differentiation of germ cells in the foetal testis.
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Affiliation(s)
- Brigitte Moniot
- Genetic and Development department, Institute of Human Genetics, CNRS UPR1142, Montpellier 34094, Cedex 05, France
| | - Safdar Ujjan
- Genetic and Development department, Institute of Human Genetics, CNRS UPR1142, Montpellier 34094, Cedex 05, France
| | - Julien Champagne
- Genetic and Development department, Institute of Human Genetics, CNRS UPR1142, Montpellier 34094, Cedex 05, France
| | - Hiroyuki Hirai
- Department of Advanced Technology and Development, BML, Matoba, Kawagoe, Saitama 350-1101, Japan
| | - Kosuke Aritake
- Department of Molecular Behavioral Biology, Osaka Bioscience Institute, Osaka 565-0874, Japan
| | - Kinya Nagata
- Department of Advanced Technology and Development, BML, Matoba, Kawagoe, Saitama 350-1101, Japan
| | - Emeric Dubois
- Plateforme MGX, Functional Genomic Institute, CNRS UMR 5203 – INSERM U 661, Montpellier 34094, Cedex 05, France
| | - Sabine Nidelet
- Plateforme MGX, Functional Genomic Institute, CNRS UMR 5203 – INSERM U 661, Montpellier 34094, Cedex 05, France
| | - Masataka Nakamura
- Human Gene Sciences Center, Tokyo Medical and Dental University, Yushima, Bunkyo-ku, Tokyo 113-8510, Japan
| | - Yoshihiro Urade
- Department of Molecular Behavioral Biology, Osaka Bioscience Institute, Osaka 565-0874, Japan
| | - Francis Poulat
- Genetic and Development department, Institute of Human Genetics, CNRS UPR1142, Montpellier 34094, Cedex 05, France
| | - Brigitte Boizet-Bonhoure
- Genetic and Development department, Institute of Human Genetics, CNRS UPR1142, Montpellier 34094, Cedex 05, France
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Cukras S, Morffy N, Ohn T, Kee Y. Inactivating UBE2M impacts the DNA damage response and genome integrity involving multiple cullin ligases. PLoS One 2014; 9:e101844. [PMID: 25025768 PMCID: PMC4099125 DOI: 10.1371/journal.pone.0101844] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Accepted: 06/12/2014] [Indexed: 12/28/2022] Open
Abstract
Protein neddylation is involved in a wide variety of cellular processes. Here we show that the DNA damage response is perturbed in cells inactivated with an E2 Nedd8 conjugating enzyme UBE2M, measured by RAD51 foci formation kinetics and cell based DNA repair assays. UBE2M knockdown increases DNA breakages and cellular sensitivity to DNA damaging agents, further suggesting heightened genomic instability and defective DNA repair activity. Investigating the downstream Cullin targets of UBE2M revealed that silencing of Cullin 1, 2, and 4 ligases incurred significant DNA damage. In particular, UBE2M knockdown, or defective neddylation of Cullin 2, leads to a blockade in the G1 to S progression and is associated with delayed S-phase dependent DNA damage response. Cullin 4 inactivation leads to an aberrantly high DNA damage response that is associated with increased DNA breakages and sensitivity of cells to DNA damaging agents, suggesting a DNA repair defect is associated. siRNA interrogation of key Cullin substrates show that CDT1, p21, and Claspin are involved in elevated DNA damage in the UBE2M knockdown cells. Therefore, UBE2M is required to maintain genome integrity by activating multiple Cullin ligases throughout the cell cycle.
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Affiliation(s)
- Scott Cukras
- Department of Cell Biology, Microbiology, and Molecular Biology, College of Arts and Sciences, University of South Florida, Tampa, Florida, United States of America
| | - Nicholas Morffy
- Department of Cell Biology, Microbiology, and Molecular Biology, College of Arts and Sciences, University of South Florida, Tampa, Florida, United States of America
| | - Takbum Ohn
- Department of Cellular & Molecular Medicine, College of Medicine, Chosun University, Gwangju, Republic of Korea
| | - Younghoon Kee
- Department of Cell Biology, Microbiology, and Molecular Biology, College of Arts and Sciences, University of South Florida, Tampa, Florida, United States of America
- * E-mail:
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Less understood issues: p21Cip1 in mitosis and its therapeutic potential. Oncogene 2014; 34:1758-67. [DOI: 10.1038/onc.2014.133] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Revised: 04/16/2014] [Accepted: 04/16/2014] [Indexed: 12/18/2022]
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Merlet J, Pintard L. Role of the CRL2(LRR-1) E3 ubiquitin-ligase in the development of the germline in C. elegans. WORM 2013; 2:e25716. [PMID: 24778939 PMCID: PMC3875651 DOI: 10.4161/worm.25716] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/05/2013] [Accepted: 07/10/2013] [Indexed: 01/16/2023]
Abstract
The ubiquitin-proteolytic system (UPS) regulates a variety of cellular and biological processes by controlling the stability of regulatory proteins, in space and time. Not surprisingly, defects in this system have been associated with various syndromes and pathologies, including cancer, illustrating the importance of understanding the regulation and the multiple functions of this system. C. elegans is a powerful model system to identify components of the UPS and to study their function during development in multicellular organisms. In C. elegans, the evolutionarily conserved CRL2LRR-1 E3-ligase is critical for the development of the germline. Inactivation of the CUL-2 scaffold or the LRR-1 substrate-recognition subunit leads to a cell cycle arrest in germline stem cells resulting in sterility. Through a genetic screen, we have identified a cul-2 temperature-sensitive allele and we have used this allele to show that CUL-2 plays multiple roles in the development of the germline. CUL-2 (1) promotes germ cell proliferation, (2) influences the balance between mitotic proliferation and meiotic differentiation, and (3) inhibits the first step of meiotic prophase. Here, we discuss how CUL-2 regulates and coordinates these different processes. We suggest that ubiquitin-mediated protein degradation constitutes an important additional layer of regulation that contributes to the spatial organization of the germline.
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Affiliation(s)
- Jorge Merlet
- Institut Jacques Monod; Monod; CNRS; UMR 7592; Univ. Paris Diderot; Sorbonne Paris Cité; F-75205 Paris, France
| | - Lionel Pintard
- Institut Jacques Monod; Monod; CNRS; UMR 7592; Univ. Paris Diderot; Sorbonne Paris Cité; F-75205 Paris, France
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Abstract
PURPOSE OF REVIEW This review provides an overview of the structure, regulation and physiological functions of p21, the product of the cyclin-dependent kinase inhibitor 1A (CDKN1A) gene, with a focus on its dual role in promoting and repressing biological processes that are hallmarks of tumourigenesis. RECENT FINDINGS Recent work has provided a better understanding of the molecular mechanisms of how oncogenic signalling pathways influence p21 expression. In response to cellular stimuli, p21 expression is tightly regulated at transcriptional and post-translational levels through mechanisms involving RNA stabilization, phosphorylation and ubiquitination. As a result, growing evidence reveals that several important tumour suppressor and oncogenic signalling pathways alter p21 expression to elicit their effects on cell cycle progression and survival. Thus, p21 expression can both promote and inhibit tumourigenic processes, depending on the cellular context. SUMMARY Since its discovery, it has become increasingly clear that p21 can function as both a classical tumour suppressor and an oncogene. In order to effectively utilize p21 as a therapeutic target, it will be necessary to design therapeutic strategies that preferentially block the ability of p21 to promote senescence, stem cell renewal and cyclin/CDK activation, while leaving its tumour suppressive functions intact.
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CRL2(LRR-1) E3-ligase regulates proliferation and progression through meiosis in the Caenorhabditis elegans germline. PLoS Genet 2013; 9:e1003375. [PMID: 23555289 PMCID: PMC3610609 DOI: 10.1371/journal.pgen.1003375] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2012] [Accepted: 01/29/2013] [Indexed: 11/19/2022] Open
Abstract
The ubiquitin-proteolytic system controls the stability of proteins in space and time. In this study, using a temperature-sensitive mutant allele of the cul-2 gene, we show that CRL2(LRR-1) (CUL-2 RING E3 ubiquitin-ligase and the Leucine Rich Repeat 1 substrate recognition subunit) acts at multiple levels to control germline development. CRL2(LRR-1) promotes germ cell proliferation by counteracting the DNA replication ATL-1 checkpoint pathway. CRL2(LRR-1) also participates in the mitotic proliferation/meiotic entry decision, presumably controlling the stability of meiotic promoting factors in the mitotic zone of the germline. Finally, CRL2(LRR-1) inhibits the first steps of meiotic prophase by targeting in mitotic germ cells degradation of the HORMA domain-containing protein HTP-3, required for loading synaptonemal complex components onto meiotic chromosomes. Given its widespread evolutionary conservation, CUL-2 may similarly regulate germline development in other organisms as well.
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Wang W, Huang J, Wang X, Yuan J, Li X, Feng L, Park JI, Chen J. PTPN14 is required for the density-dependent control of YAP1. Genes Dev 2012; 26:1959-71. [PMID: 22948661 DOI: 10.1101/gad.192955.112] [Citation(s) in RCA: 151] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Through an shRNA-mediated loss-of-function screen, we identified PTPN14 as a potential tumor suppressor. PTPN14 interacts with yes-associated protein 1 (YAP1), a member of the hippo signaling pathway. We showed that PTPN14 promotes the nucleus-to-cytoplasm translocation of YAP1 during contact inhibition and thus inhibits YAP1 transactivation activity. Interestingly, PTPN14 protein stability was positively controlled by cell density. We identified the CRL2(LRR1) (cullin2 RING ubiquitin ligase complex/leucine-rich repeat protein 1) complex as the E3 ligase that targets PTPN14 for degradation at low cell density. Collectively, these data suggest that PTPN14 acts to suppress cell proliferation by promoting cell density-dependent cytoplasmic translocation of YAP1.
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Affiliation(s)
- Wenqi Wang
- Department of Experimental Radiation Oncology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030, USA
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Dai M, Al-Odaini AA, Arakelian A, Rabbani SA, Ali S, Lebrun JJ. A novel function for p21Cip1 and acetyltransferase p/CAF as critical transcriptional regulators of TGFβ-mediated breast cancer cell migration and invasion. Breast Cancer Res 2012; 14:R127. [PMID: 22995475 PMCID: PMC4053104 DOI: 10.1186/bcr3322] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2012] [Accepted: 08/24/2012] [Indexed: 12/20/2022] Open
Abstract
Introduction Tumor cell migration and invasion are critical initiation steps in the process of breast cancer metastasis, the primary cause of breast cancer morbidity and death. Here we investigated the role of p21Cip1 (p21), a member of the core cell cycle machinery, in transforming growth factor-beta (TGFβ)-mediated breast cancer cell migration and invasion. Methods A mammary fat pad xenograft mouse model was used to assess the mammary tumor growth and local invasion. The triple negative human breast cancer cell lines MDA-MB231 and its sub-progenies SCP2 and SCP25, SUM159PT, SUM149PT, SUM229PE and SUM1315MO2 were treated with 5 ng/ml TGFβ and the protein expression levels were measured by Western blot. Cell migration and invasion were examined using the scratch/wound healing and Transwell assay. TGFβ transcriptional activity was measured by a TGFβ/Smad reporter construct (CAGA12-luc) using luciferase assay. q-PCR was used for assessing TGFβ downstream target genes. The interactions among p21, p/CAF and Smad3 were performed by co-immunoprecipitation. In addition, Smad3 on DNA binding ability was measured by DNA immunoprecipitation using biotinylated Smad binding element DNA probes. Finally, the association among active TGFβ/Smad signaling, p21 and p/CAF with lymph node metastasis was examined by immunohistochemistry in tissue microarray containing 50 invasive ductal breast tumors, 25 of which are lymph node positive. Results We found p21 expression to correlate with poor overall and distant metastasis free survival in breast cancer patients. Furthermore, using xenograft animal models and in vitro studies, we found p21 to be essential for tumor cell invasion. The invasive effects of p21 were found to correlate with Smad3, and p/CAF interaction downstream of TGFβ. p21 and p/CAF regulates TGFβ-mediated transcription of pro-metastatic genes by controlling Smad3 acetylation, DNA binding and transcriptional activity. In addition, we found that active TGFβ/Smad signaling correlates with high p21 and p/CAF expression levels and lymph node involvement using tissue microarrays from breast cancer patients. Conclusions Together these results highlight an important role for p21 and p/CAF in promoting breast cancer cell migration and invasion at the transcriptional level and may open new avenues for breast cancer therapy.
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Okumura F, Matsuzaki M, Nakatsukasa K, Kamura T. The Role of Elongin BC-Containing Ubiquitin Ligases. Front Oncol 2012; 2:10. [PMID: 22649776 PMCID: PMC3355856 DOI: 10.3389/fonc.2012.00010] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2011] [Accepted: 01/17/2012] [Indexed: 02/06/2023] Open
Abstract
The Elongin complex was originally identified as a positive regulator of RNA polymerase II and is composed of a transcriptionally active subunit (A) and two regulatory subunits (B and C). The Elongin BC complex enhances the transcriptional activity of Elongin A. “Classical” SOCS box-containing proteins interact with the Elongin BC complex and have ubiquitin ligase activity. They also interact with the scaffold protein Cullin (Cul) and the RING domain protein Rbx and thereby are members of the Cullin RING ligase (CRL) superfamily. The Elongin BC complex acts as an adaptor connecting Cul and SOCS box proteins. Recently, it was demonstrated that classical SOCS box proteins can be further divided into two groups, Cul2- and Cul5-type proteins. The classical SOCS box-containing protein pVHL is now classified as a Cul2-type protein. The Elongin BC complex containing CRL family is now considered two distinct protein assemblies, which play an important role in regulating a variety of cellular processes such as tumorigenesis, signal transduction, cell motility, and differentiation.
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Affiliation(s)
- Fumihiko Okumura
- Division of Biological Science, Graduate School of Science, Nagoya University Nagoya, Aichi, Japan
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Multiple degradation pathways regulate versatile CIP/KIP CDK inhibitors. Trends Cell Biol 2011; 22:33-41. [PMID: 22154077 DOI: 10.1016/j.tcb.2011.10.004] [Citation(s) in RCA: 119] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2011] [Revised: 10/18/2011] [Accepted: 10/24/2011] [Indexed: 01/06/2023]
Abstract
The mammalian CIP/KIP family of cyclin-dependent kinase (CDK) inhibitors (CKIs) comprises three proteins--p21(Cip1/WAF1), p27(Kip1), and p57(Kip2)--that bind and inhibit cyclin-CDK complexes, which are key regulators of the cell cycle. CIP/KIP CKIs have additional independent functions in regulating transcription, apoptosis and actin cytoskeletal dynamics. These divergent functions are performed in distinct cellular compartments and contribute to the seemingly contradictory observation that the CKIs can both suppress and promote cancer. Multiple ubiquitin ligases (E3s) direct the proteasome-mediated degradation of p21, p27 and p57. This review analyzes recent data highlighting our current understanding of how distinct E3 pathways regulate subpopulations of the CKIs to control their diverse functions.
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Darzynkiewicz Z. Redundancy in response to DNA damage: the key to protection of genome integrity. Cell Cycle 2011; 10:3425. [PMID: 22024932 DOI: 10.4161/cc.10.20.17525] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
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Liu Q, Mier JW, Panka DJ. Differential modulatory effects of GSK-3β and HDM2 on sorafenib-induced AIF nuclear translocation (programmed necrosis) in melanoma. Mol Cancer 2011; 10:115. [PMID: 21929745 PMCID: PMC3189171 DOI: 10.1186/1476-4598-10-115] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2011] [Accepted: 09/19/2011] [Indexed: 01/08/2023] Open
Abstract
Background GSK-3β phosphorylates numerous substrates that govern cell survival. It phosphorylates p53, for example, and induces its nuclear export, HDM2-dependent ubiquitination, and proteasomal degradation. GSK-3β can either enhance or inhibit programmed cell death, depending on the nature of the pro-apoptotic stimulus. We previously showed that the multikinase inhibitor sorafenib activated GSK-3β and that this activation attenuated the cytotoxic effects of the drug in various BRAF-mutant melanoma cell lines. In this report, we describe the results of studies exploring the effects of GSK-3β on the cytotoxicity and antitumor activity of sorafenib combined with the HDM2 antagonist MI-319. Results MI-319 alone increased p53 levels and p53-dependent gene expression in melanoma cells but did not induce programmed cell death. Its cytotoxicity, however, was augmented in some melanoma cell lines by the addition of sorafenib. In responsive cell lines, the MI-319/sorafenib combination induced the disappearance of p53 from the nucleus, the down modulation of Bcl-2 and Bcl-xL, the translocation of p53 to the mitochondria and that of AIF to the nuclei. These events were all GSK-3β-dependent in that they were blocked with a GSK-3β shRNA and facilitated in otherwise unresponsive melanoma cell lines by the introduction of a constitutively active form of the kinase (GSK-3β-S9A). These modulatory effects of GSK-3β on the activities of the sorafenib/MI-319 combination were the exact reverse of its effects on the activities of sorafenib alone, which induced the down modulation of Bcl-2 and Bcl-xL and the nuclear translocation of AIF only in cells in which GSK-3β activity was either down modulated or constitutively low. In A375 xenografts, the antitumor effects of sorafenib and MI-319 were additive and associated with the down modulation of Bcl-2 and Bcl-xL, the nuclear translocation of AIF, and increased suppression of tumor angiogenesis. Conclusions Our data demonstrate a complex partnership between GSK-3β and HDM2 in the regulation of p53 function in the nucleus and mitochondria. The data suggest that the ability of sorafenib to activate GSK-3β and alter the intracellular distribution of p53 may be exploitable as an adjunct to agents that prevent the HDM2-dependent degradation of p53 in the treatment of melanoma.
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Affiliation(s)
- Qingjun Liu
- Division of Hematology-Oncology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA, USA
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Abstract
Morphogenesis is an important component of animal development. Genetic redundancy has been proposed to be common among morphogenesis genes, posing a challenge to the genetic dissection of morphogenesis mechanisms. Genetic redundancy is more generally a challenge in biology, as large proportions of the genes in diverse organisms have no apparent loss of function phenotypes. Here, we present a screen designed to uncover redundant and partially redundant genes that function in an example of morphogenesis, gastrulation in Caenorhabditis elegans. We performed an RNA interference (RNAi) enhancer screen in a gastrulation-sensitized double-mutant background, targeting genes likely to be expressed in gastrulating cells or their neighbors. Secondary screening identified 16 new genes whose functions contribute to normal gastrulation in a nonsensitized background. We observed that for most new genes found, the closest known homologs were multiple other C. elegans genes, suggesting that some may have derived from rounds of recent gene duplication events. We predict that such genes are more likely than single copy genes to comprise redundant or partially redundant gene families. We explored this prediction for one gene that we identified and confirmed that this gene and five close relatives, which encode predicted substrate recognition subunits (SRSs) for a CUL-2 ubiquitin ligase, do indeed function partially redundantly with each other in gastrulation. Our results implicate new genes in C. elegans gastrulation, and they show that an RNAi-based enhancer screen in C. elegans can be used as an efficient means to identify important but redundant or partially redundant developmental genes.
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Abstract
Just as the activity of many multifunctional proteins is restricted by subcellular localization, so is their regulation. In this issue of Development Cell, Starostina et al. identify an E3 ubiquitin ligase, CRL2(LRR1), for the cyclin-dependent kinase inhibitor p21 that specifically ubiquitylates cytoplasmic p21 to facilitate cell migration.
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Affiliation(s)
- Yue Xiong
- Department of Biochemistry and Biophysics, Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, NC 27599, USA.
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Jia L, Bickel JS, Wu J, Morgan MA, Li H, Yang J, Yu X, Chan RC, Sun Y. RBX1 (RING box protein 1) E3 ubiquitin ligase is required for genomic integrity by modulating DNA replication licensing proteins. J Biol Chem 2010; 286:3379-86. [PMID: 21115485 DOI: 10.1074/jbc.m110.188425] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
RBX1 (RING box protein 1), also known as ROC1 (Regulator of Cullin 1), is an essential component of SCF (Skp1/Cullins/F-box) E3 ubiquitin ligases, which target diverse proteins for proteasome-mediated degradation. Our recent study showed that RBX1 silencing triggered a DNA damage response (DDR) leading to G(2)-M arrest, senescence, and apoptosis, with the mechanism remaining elusive. Here, we show that, in human cancer cells, RBX1 silencing causes the accumulation of DNA replication licensing proteins CDT1 and ORC1, leading to DNA double-strand breaks, DDR, G(2) arrest, and, eventually, aneuploidy. Whereas CHK1 activation by RBX1 silencing is responsible for the G(2) arrest, enhanced DNA damage renders cancer cells more sensitive to radiation. In Caenorhabditis elegans, RBX-1 silencing causes CDT-1 accumulation, triggering DDR in intestinal cells, which is largely abrogated by simultaneous CDT-1 silencing. RBX-1 silencing also induces lethality during development of embryos and in adulthood. Thus, RBX1 E3 ligase is essential for the maintenance of mammalian genome integrity and the proper development and viability in C. elegans.
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Affiliation(s)
- Lijun Jia
- Division of Radiation and Cancer Biology, Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan 48109, USA.
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