1
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Liu D, Sonalkar J, Prasanth SG. ORChestra coordinates the replication and repair music. Bioessays 2023; 45:e2200229. [PMID: 36811379 PMCID: PMC10023367 DOI: 10.1002/bies.202200229] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 02/03/2023] [Accepted: 02/06/2023] [Indexed: 02/24/2023]
Abstract
Error-free genome duplication and accurate cell division are critical for cell survival. In all three domains of life, bacteria, archaea, and eukaryotes, initiator proteins bind replication origins in an ATP-dependent manner, play critical roles in replisome assembly, and coordinate cell-cycle regulation. We discuss how the eukaryotic initiator, Origin recognition complex (ORC), coordinates different events during the cell cycle. We propose that ORC is the maestro driving the orchestra to coordinately perform the musical pieces of replication, chromatin organization, and repair.
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Affiliation(s)
- Dazhen Liu
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, 601S Goodwin Avenue, Urbana, IL 61801 USA
| | - Jay Sonalkar
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, 601S Goodwin Avenue, Urbana, IL 61801 USA
| | - Supriya G. Prasanth
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, 601S Goodwin Avenue, Urbana, IL 61801 USA
- Cancer center at Illinois, UIUC
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2
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Anachkova BB, Djeliova VL. Stability of proteins involved in initiation of DNA replication in UV damaged human cells. ACTA ACUST UNITED AC 2021; 77:113-123. [PMID: 34333892 DOI: 10.1515/znc-2020-0286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Accepted: 07/17/2021] [Indexed: 11/15/2022]
Abstract
The protein stability of the initiation factors Orc2, Orc3, Orc4, and Cdc6 was analyzed after UV light exposure in two human cell lines. In the cell line with higher repair capacity, HEK 293, no changes in the cell cycle distribution or in the protein levels of the investigated factors were detected. In HeLa cells that are characterized by lower repair capacity, UV irradiation caused a reduction of the levels of Cdc6, Orc2 and Orc3, but not of Orc4 or triggered apoptosis. The appearance of the truncated 49 kDa form of Cdc6 suggested the involvement of the caspase pathway in the degradation of the proteins. Reduced protein levels of Cdc6 were detected in UV damaged HeLa cells in which the apoptotic process was blocked with the caspase inhibitor Z-VAD-fmk, indicating that the degradation of Cdc6 is mediated by the proteasome pathway instead. In the presence of caffeine, an inhibitor of the cell cycle checkpoint kinases, Cdc6 was stabilized, demonstrating that its degradation is controlled by the DNA damage cell cycle checkpoint. We conclude that in response to DNA damage, the activation of origins of replication can be prevented by the degradation of Cdc6, most likely through the proteasome pathway.
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Affiliation(s)
- Boyka Borisova Anachkova
- Department of the Molecular Biology of the Cell Cycle, Institute of Molecular Biology "RoumenTsanev", Bulgarian Academy of Sciences, Akad. G. Bonchev Street, Bl. 21, Sofia1113, Bulgaria
| | - Vera Lyubchova Djeliova
- Department of the Molecular Biology of the Cell Cycle, Institute of Molecular Biology "RoumenTsanev", Bulgarian Academy of Sciences, Akad. G. Bonchev Street, Bl. 21, Sofia1113, Bulgaria
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3
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Zhao M, Wang Y, Zhao Y, He S, Zhao R, Song Y, Cheng J, Gong Y, Xie J, Wang Y, Hu B, Tian L, Huang Q. Caspase-3 knockout attenuates radiation-induced tumor repopulation via impairing the ATM/p53/Cox-2/PGE 2 pathway in non-small cell lung cancer. Aging (Albany NY) 2020; 12:21758-21776. [PMID: 33180744 PMCID: PMC7695367 DOI: 10.18632/aging.103984] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Accepted: 07/14/2020] [Indexed: 12/14/2022]
Abstract
Radiotherapy is an effective treatment for non-small cell lung cancer (NSCLC). However, irradiated, dying tumor cells generate potent growth stimulatory signals during radiotherapy that promote the repopulation of adjacent surviving tumor cells to cause tumor recurrence. We investigated the function of caspase-3 in NSCLC repopulation after radiotherapy. We found that radiotherapy induced a DNA damage response (DDR), activated caspase-3, and promoted tumor repopulation in NSCLC cells. Unexpectedly, caspase-3 knockout attenuated the ataxia-telangiectasia mutated (ATM)/p53-initiated DDR by decreasing nuclear migration of endonuclease G (EndoG), thereby reducing the growth-promoting effect of irradiated, dying tumor cells. We also identified p53 as a regulator of the Cox-2/PGE2 axis and its involvement in caspase-3-induced tumor repopulation after radiotherapy. In addition, injection of caspase-3 knockout NSCLC cells impaired tumor growth in a nude mouse model. Our findings reveal that caspase-3 promotes tumor repopulation in NSCLC cells by activating DDR and the downstream Cox-2/PGE2 axis. Thus, caspase-3-induced ATM/p53/Cox-2/PGE2 signaling pathway could provide potential therapeutic targets to reduce NSCLC recurrence after radiotherapy.
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Affiliation(s)
- Minghui Zhao
- Cancer Center, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 201620, China
| | - Yiwei Wang
- Cancer Center, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 201620, China
| | - Yucui Zhao
- Cancer Center, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 201620, China
| | - Sijia He
- Cancer Center, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 201620, China
| | - Ruyi Zhao
- Cancer Center, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 201620, China
| | - Yanwei Song
- Cancer Center, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 201620, China
| | - Jin Cheng
- Cancer Center, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 201620, China
| | - Yanping Gong
- Cancer Center, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 201620, China
| | - Jianzhu Xie
- Cancer Center, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 201620, China
| | - Yulan Wang
- Cancer Center, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 201620, China
| | - Binjie Hu
- Cancer Center, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 201620, China
| | - Ling Tian
- Shanghai Key Laboratory for Pancreatic Diseases, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 201620, China.,Department of Central Laboratory, Shanghai Chest Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200030, China
| | - Qian Huang
- Cancer Center, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 201620, China
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4
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Wang C, Chang CC, Wang L, Yuan F. Inhibition of Caspases Improves Non-Viral T Cell Receptor Editing. Cancers (Basel) 2020; 12:E2603. [PMID: 32933048 PMCID: PMC7565551 DOI: 10.3390/cancers12092603] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2020] [Revised: 09/04/2020] [Accepted: 09/08/2020] [Indexed: 12/13/2022] Open
Abstract
T cell receptor (TCR) knockout is a critical step in producing universal chimeric antigen receptor T cells for cancer immunotherapy. A promising approach to achieving the knockout is to deliver the CRISPR/Cas9 system into cells using electrotransfer technology. However, clinical applications of the technology are currently limited by the low cell viability. In this study, we attempt to solve the problem by screening small molecule drugs with an immortalized human T cell line, Jurkat clone E6-1, for inhibition of apoptosis. The study identifies a few caspase inhibitors that could be used to simultaneously enhance the cell viability and the efficiency of plasmid DNA electrotransfer. Additionally, we show that the enhancement could be achieved through knockdown of caspase 3 expression in siRNA treated cells, suggesting that the cell death in electrotransfer experiments was caused mainly by caspase 3-dependent apoptosis. Finally, we investigated if the caspase inhibitors could improve TCR gene-editing with electrotransferred ribonucleoprotein, a complex of Cas9 protein and a T cell receptor-α constant (TRAC)-targeting single guide RNA (sgRNA). Our data showed that inhibition of caspases post electrotransfer could significantly increase cell viability without compromising the TCR disruption efficiency. These new findings can be used to improve non-viral T cell engineering.
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Affiliation(s)
| | | | | | - Fan Yuan
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA; (C.W.); (C.-C.C.); or (L.W.)
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5
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Chen B, Wen P, Hu G, Gao Y, Qi X, Zhu K, Chen S, Wu L, Xu A, Zhao G. Antagonizing CDK8 Sensitizes Colorectal Cancer to Radiation Through Potentiating the Transcription of e2f1 Target Gene apaf1. Front Cell Dev Biol 2020; 8:408. [PMID: 32596239 PMCID: PMC7304162 DOI: 10.3389/fcell.2020.00408] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Accepted: 05/04/2020] [Indexed: 12/12/2022] Open
Abstract
Radiotherapy is an essential curative treatment modality for colorectal cancer. Apoptosis is the major mechanism of IR-induced cell death and aberrant apoptotic signaling results in radioresistance, which is a hallmark of most, perhaps all, types of human cancers. Potentiating the induction of apoptosis is an emerging strategy for cancer radiotherapy. Here, we determined that targeting CDK8 selectively radiosensitized colorectal cancer through the mitochondria-dependent intrinsic apoptotic signaling, which was mediated through the induction of the transcription of apaf1 that was e2f1- and not p53-dependent. Importantly, the enhanced transcriptional activity of e2f1 was dependent on the kinase activity of CDK8 itself and not on the assembling of the mediator complex. In addition, clinical inhibitor, and in vivo studies confirmed the radiosensitizing effect of CDK8. Our results provide a new targeting strategy to improve the radiotherapy of CRC.
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Affiliation(s)
- Bin Chen
- Key Laboratory of High Magnetic Field and Ion Beam Physical Biology, Anhui Province Key Laboratory of Environmental Toxicology and Pollution Control Technology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, China.,University of Science and Technology of China, Hefei, China
| | - Pengbo Wen
- Key Laboratory of High Magnetic Field and Ion Beam Physical Biology, Anhui Province Key Laboratory of Environmental Toxicology and Pollution Control Technology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, China.,University of Science and Technology of China, Hefei, China
| | - Guanshuo Hu
- Key Laboratory of High Magnetic Field and Ion Beam Physical Biology, Anhui Province Key Laboratory of Environmental Toxicology and Pollution Control Technology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, China.,University of Science and Technology of China, Hefei, China
| | - Yang Gao
- Key Laboratory of High Magnetic Field and Ion Beam Physical Biology, Anhui Province Key Laboratory of Environmental Toxicology and Pollution Control Technology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, China.,University of Science and Technology of China, Hefei, China
| | - Xiaojing Qi
- Key Laboratory of High Magnetic Field and Ion Beam Physical Biology, Anhui Province Key Laboratory of Environmental Toxicology and Pollution Control Technology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, China.,University of Science and Technology of China, Hefei, China
| | - Kaili Zhu
- Key Laboratory of High Magnetic Field and Ion Beam Physical Biology, Anhui Province Key Laboratory of Environmental Toxicology and Pollution Control Technology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, China.,University of Science and Technology of China, Hefei, China
| | - Shaopeng Chen
- Key Laboratory of High Magnetic Field and Ion Beam Physical Biology, Anhui Province Key Laboratory of Environmental Toxicology and Pollution Control Technology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, China
| | - Lijun Wu
- Key Laboratory of High Magnetic Field and Ion Beam Physical Biology, Anhui Province Key Laboratory of Environmental Toxicology and Pollution Control Technology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, China
| | - An Xu
- Key Laboratory of High Magnetic Field and Ion Beam Physical Biology, Anhui Province Key Laboratory of Environmental Toxicology and Pollution Control Technology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, China
| | - Guoping Zhao
- Key Laboratory of High Magnetic Field and Ion Beam Physical Biology, Anhui Province Key Laboratory of Environmental Toxicology and Pollution Control Technology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, China
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6
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Connolly P, Garcia-Carpio I, Villunger A. Cell-Cycle Cross Talk with Caspases and Their Substrates. Cold Spring Harb Perspect Biol 2020; 12:a036475. [PMID: 31727679 PMCID: PMC7263087 DOI: 10.1101/cshperspect.a036475] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Caspases play central roles in mediating both cell death and inflammation. It has more recently become evident that caspases also drive other biological processes. Most prominently, caspases have been shown to be involved in differentiation. Several stem and progenitor cell types rely on caspases to initiate and execute their differentiation processes. These range from neural and glial cells, to skeletal myoblasts and osteoblasts, and several cell types of the hematopoietic system. Beyond differentiation, caspases have also been shown to play roles in other "noncanonical" processes, including cell proliferation, arrest, and senescence, thereby contributing to the mechanisms that regulate tissue homeostasis at multiple levels. Remarkably, caspases directly influence the course of the cell cycle in both a positive and negative manner. Caspases both cleave elements of the cell-cycle machinery and are themselves substrates of cell-cycle kinases. Here we aim to summarize the breadth of interactions between caspases and cell-cycle regulators. We also highlight recent developments in this area.
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Affiliation(s)
- Patrick Connolly
- Division of Developmental Immunology, Biocenter, Medical University of Innsbruck, Innsbruck 6020, Austria
| | - Irmina Garcia-Carpio
- Division of Developmental Immunology, Biocenter, Medical University of Innsbruck, Innsbruck 6020, Austria
| | - Andreas Villunger
- Division of Developmental Immunology, Biocenter, Medical University of Innsbruck, Innsbruck 6020, Austria
- Ludwig Boltzmann Institute for Rare and Undiagnosed Diseases, Vienna 1090, Austria
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna 1090, Austria
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7
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Yavuz S, Çetin A, Akdemir A, Doyduk D, Dişli A, Çelik Turgut G, Şen A, Yıldırır Y. Synthesis and Functional Investigations of Computer Designed Novel Cladribine-Like Compounds for the Treatment of Multiple Sclerosis. Arch Pharm (Weinheim) 2017; 350. [PMID: 28960496 DOI: 10.1002/ardp.201700185] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Revised: 08/29/2017] [Accepted: 09/05/2017] [Indexed: 12/08/2022]
Abstract
Cladribine (2-CdA) is used as an anti-cancer drug but is currently studied as a potential treatment for use in relapsing-remitting multiple sclerosis (MS). In this study, we computer designed, synthesized, and characterized two novel derivatives of 2-CdA, K1-5d and K2-4c, and investigated their underlying mechanism of beneficial effect using the CCRF-CEM and RAJI cell lines. For this purpose, we first determined their effect on MS and DNA damage and repair-related gene expression profiles using custom arrays along with 2-CdA treatment at non-toxic doses. Then, we determined whether cells underwent apoptosis after treatment with 2-CdA, K1-5d, and K2-4c in CCRF-CEM and RAJI cells, using the DNA fragmentation assay. It was found that both derivatives modulated the expression of the pathway-related genes that are important in inflammatory signaling, apoptosis, ATM/ATR, double-strand break repair, and the cell cycle. Furthermore, 2-CdA, K1-5d, and K2-4c significantly activated apoptosis in both cell lines. In summary, our data demonstrate that although both derivatives act as anti-inflammatory and apoptotic agents, inducing the accumulation of DNA strand breaks and activating the ultimate tumor suppressor p53 in T and B lymphocytes, the K1-5d derivative has shown more promising activities for further studies.
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Affiliation(s)
- Serkan Yavuz
- Faculty of Science, Department of Chemistry, Gazi University, Ankara, Turkey
| | - Aysu Çetin
- Faculty of Science, Department of Chemistry, Gazi University, Ankara, Turkey
| | - Atilla Akdemir
- Faculty of Pharmacy, Department of Pharmacology, Bezmialem Vakıf University, İstanbul, Turkey
| | - Doğukan Doyduk
- Faculty of Science, Department of Chemistry, Gazi University, Ankara, Turkey
| | - Ali Dişli
- Faculty of Science, Department of Chemistry, Gazi University, Ankara, Turkey
| | - Gurbet Çelik Turgut
- Faculty of Arts and Sciences, Department of Biology, Pamukkale University, Kınıklı, Denizli, Turkey
| | - Alaattin Şen
- Faculty of Arts and Sciences, Department of Biology, Pamukkale University, Kınıklı, Denizli, Turkey
| | - Yılmaz Yıldırır
- Faculty of Science, Department of Chemistry, Gazi University, Ankara, Turkey
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8
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Beggs KM, Maiuri AR, Fullerton AM, Poulsen KL, Breier AB, Ganey PE, Roth RA. Trovafloxacin-induced replication stress sensitizes HepG2 cells to tumor necrosis factor-alpha-induced cytotoxicity mediated by extracellular signal-regulated kinase and ataxia telangiectasia and Rad3-related. Toxicology 2015; 331:35-46. [PMID: 25748550 DOI: 10.1016/j.tox.2015.03.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2014] [Revised: 02/11/2015] [Accepted: 03/04/2015] [Indexed: 01/23/2023]
Abstract
Use of the fluoroquinolone antibiotic trovafloxacin (TVX) was restricted due to idiosyncratic, drug-induced liver injury (IDILI). Previous studies demonstrated that tumor necrosis factor-alpha (TNF) and TVX interact to cause death of hepatocytes in vitro that was associated with prolonged activation of c-Jun N-terminal kinase (JNK), activation of caspases 9 and 3, and DNA damage. The purpose of this study was to explore further the mechanism by which TVX interacts with TNF to cause cytotoxicity. Treatment with TVX caused cell cycle arrest, enhanced expression of p21 and impaired proliferation, but cell death only occurred after cotreatment with TVX and TNF. Cell death involved activation of extracellular signal-related kinase (ERK), which in turn activated caspase 3 and ataxia telangiectasia and Rad3-related (ATR), both of which contributed to cytotoxicity. Cotreatment of HepG2 cells with TVX and TNF caused double-strand breaks in DNA, and ERK contributed to this effect. Inhibition of caspase activity abolished the DNA strand breaks. The data suggest a complex interaction of TVX and TNF in which TVX causes replication stress, and the downstream effects are exacerbated by TNF, leading to hepatocellular death. These results raise the possibility that IDILI from TVX results from MAPK and ATR activation in hepatocytes initiated by interaction of cytokine signaling with drug-induced replication stress.
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Affiliation(s)
- Kevin M Beggs
- Michigan State University, Department of Pharmacology & Toxicology, Center for Integrative Toxicology, 1129 Farm Lane, East Lansing, MI 48824, United States
| | - Ashley R Maiuri
- Michigan State University, Department of Pharmacology & Toxicology, Center for Integrative Toxicology, 1129 Farm Lane, East Lansing, MI 48824, United States
| | - Aaron M Fullerton
- Michigan State University, Department of Pharmacology & Toxicology, Center for Integrative Toxicology, 1129 Farm Lane, East Lansing, MI 48824, United States
| | - Kyle L Poulsen
- Michigan State University, Department of Pharmacology & Toxicology, Center for Integrative Toxicology, 1129 Farm Lane, East Lansing, MI 48824, United States
| | - Anna B Breier
- Michigan State University, Department of Pharmacology & Toxicology, Center for Integrative Toxicology, 1129 Farm Lane, East Lansing, MI 48824, United States
| | - Patricia E Ganey
- Michigan State University, Department of Pharmacology & Toxicology, Center for Integrative Toxicology, 1129 Farm Lane, East Lansing, MI 48824, United States
| | - Robert A Roth
- Michigan State University, Department of Pharmacology & Toxicology, Center for Integrative Toxicology, 1129 Farm Lane, East Lansing, MI 48824, United States.
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9
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Quantitative proteomics of Xenopus laevis embryos: expression kinetics of nearly 4000 proteins during early development. Sci Rep 2014; 4:4365. [PMID: 24626130 PMCID: PMC3953746 DOI: 10.1038/srep04365] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2014] [Accepted: 02/17/2014] [Indexed: 02/07/2023] Open
Abstract
While there is a rich literature on transcription dynamics during the development of many organisms, protein data is limited. We used iTRAQ isotopic labeling and mass spectrometry to generate the largest developmental proteomic dataset for any animal. Expression dynamics of nearly 4,000 proteins of Xenopuslaevis was generated from fertilized egg to neurula embryo. Expression clusters into groups. The cluster profiles accurately reflect the major events that mark changes in gene expression patterns during early Xenopus development. We observed decline in the expression of ten DNA replication factors after the midblastula transition (MBT), including a marked decline of the licensing factor XCdc6. Ectopic expression of XCdc6 leads to apoptosis; temporal changes in this protein are critical for proper development. Measurement of expression in single embryos provided no evidence for significant protein heterogeneity between embryos at the same stage of development.
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10
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Liu L, Yim H, Choi JH, Kim ST, Jin Y, Lee SK. ATM kinase promotes both caspase-8 and caspase-9 activation during TNF-α-induced apoptosis of HeLa cells. FEBS Lett 2014; 588:929-35. [PMID: 24530529 DOI: 10.1016/j.febslet.2014.01.050] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2013] [Revised: 12/31/2013] [Accepted: 01/04/2014] [Indexed: 11/24/2022]
Abstract
In this study, we show that atraxia telangiectasia mutated kinase (ATM) activity is generally upregulated by different apoptotic stimuli, i.e. TNF-α, TRAIL, paclitaxel, or UV. Apoptotic progression is markedly attenuated by siATM-RNA through down regulation of caspase-8 and caspase-9 in parallel with decreases in FLIP-S (short form of cellular FLICE inhibitory protein) protein levels and Bid cleavage. In addition, ATM activity is upregulated through t-Cdc6 while caspase-8 and caspase-9 activities increase. Taken together, we suggest that ATM regulates caspase-8 activation by influencing levels of FLIP-S, ATM kinase activity is upregulated by t-Cdc6, and increased ATM activity plays an essential role in the amplification of apoptosis in TNF-α-stimulated HeLa cells.
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Affiliation(s)
- Linhua Liu
- Department of Biochemistry, Institute of Glycobiology, Dalian Medical University, 9 South Lvshun Road Western Section, Dalian, 116044 Liaoning, China; Division of Pharmaceutical Biosciences, Research Institute for Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Seoul 151-742, South Korea.
| | - Hyungshin Yim
- Division of Pharmaceutical Biosciences, Research Institute for Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Seoul 151-742, South Korea; Department of Pharmacy, College of Pharmacy, Hanyang University, 55 Hanyangdaehak-ro, Sangrok-gu, Ansan, Kyeonggi-do 426-791, South Korea
| | - Jae Hyuk Choi
- Division of Pharmaceutical Biosciences, Research Institute for Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Seoul 151-742, South Korea
| | - Seung-Tak Kim
- Division of Pharmaceutical Biosciences, Research Institute for Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Seoul 151-742, South Korea
| | - Yinghua Jin
- Department of Life Science, Jilin University, Jiefang Road, Changchun, China
| | - Seung Ki Lee
- Division of Pharmaceutical Biosciences, Research Institute for Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Seoul 151-742, South Korea
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11
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Hwang IS, Woo SU, Park JW, Lee SK, Yim H. Two nuclear export signals of Cdc6 are differentially associated with CDK-mediated phosphorylation residues for cytoplasmic translocation. BIOCHIMICA ET BIOPHYSICA ACTA 2014; 1843:223-33. [PMID: 24216307 DOI: 10.1016/j.bbamcr.2013.10.024] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2013] [Revised: 10/25/2013] [Accepted: 10/31/2013] [Indexed: 11/16/2022]
Abstract
Cdc6 is cleaved at residues 442 and 290 by caspase-3 during apoptosis producing p49-tCdc6 and p32-tCdc6, respectively. While p32-tCdc6 is unable to translocate into the cytoplasm, p49-tCdc6 retains cytoplasmic translocation activity, but it has a lower efficiency than wild-type Cdc6. We hypothesized that a novel nuclear export signal (NES) sequence exists between amino acids 290 and 442. Cdc6 contains a novel NES in the region of amino acids 300-315 (NES2) that shares sequence similarity with NES1 at residues 462-476. In mutant versions of Cdc6, we replaced leucine with alanine in NES1 and NES2 and co-expressed the mutant constructs with cyclin A. We observed that the cytoplasmic translocation of these mutants was reduced in comparison to wild-type Cdc6. Moreover, the cytoplasmic translocation of a mutant in which all four leucine residues were mutated to alanine was significantly inhibited in comparison to the translocation of wild-type Cdc6. The Crm1 binding activities of Cdc6 NES mutants were consistent with the efficiency of its cytoplasmic translocation. Further studies have revealed that L468 and L470 of NES1 are required for cytoplasmic translocation of Cdc6 phosphorylated at S74, while L311 and L313 of NES2 accelerate the cytoplasmic translocation of Cdc6 phosphorylated at S54. These results suggest that the two NESs of Cdc6 work cooperatively and distinctly for the cytoplasmic translocation of Cdc6 phosphorylated at S74 and S54 by cyclin A/Cdk2.
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Affiliation(s)
- In Sun Hwang
- Division of Pharmaceutical Biosciences, Research Institute for Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Seoul 151-742, Republic of Korea
| | - Sang Uk Woo
- Department of Pharmacy, College of Pharmacy, Institute of Pharmaceutical Science and Technology, Hanyang University, Ansan, Gyeonggi-do 426-791, Republic of Korea
| | - Ji-Woong Park
- Division of Pharmaceutical Biosciences, Research Institute for Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Seoul 151-742, Republic of Korea
| | - Seung Ki Lee
- Division of Pharmaceutical Biosciences, Research Institute for Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Seoul 151-742, Republic of Korea
| | - Hyungshin Yim
- Department of Pharmacy, College of Pharmacy, Institute of Pharmaceutical Science and Technology, Hanyang University, Ansan, Gyeonggi-do 426-791, Republic of Korea.
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12
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Solier S, Pommier Y. The nuclear γ-H2AX apoptotic ring: implications for cancers and autoimmune diseases. Cell Mol Life Sci 2014; 71:2289-97. [PMID: 24448903 DOI: 10.1007/s00018-013-1555-2] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2013] [Revised: 12/11/2013] [Accepted: 12/30/2013] [Indexed: 01/10/2023]
Abstract
Apoptosis is a fundamental process for metazoan development. It is also relevant to the pathophysiology of immune diseases and cancers and to the outcome of cancer chemotherapies, as well as being a target for cancer therapies. Apoptosis involves intrinsic pathways typically initiated by DNA damaging agents and engaging mitochondria, and extrinsic pathways typically initiated by "death receptors" and their ligands TRAIL and TNF at the cell surface. Recently, we discovered the apoptotic ring, which microscopically looks like a nuclear annular staining early in apoptosis. This ring is, in three-dimensional space, a thick intranuclear shell consisting of epigenetic modifications including histone H2AX and DNA damage response (DDR) proteins. It excludes the DNA repair factors usually associated with γ-H2AX in the DDR nuclear foci. Here, we summarize our knowledge of the apoptotic ring, and discuss its biological and pathophysiological relevance, as well as its value as a potential pharmacodynamic biomarker for anticancer therapies.
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Affiliation(s)
- Stéphanie Solier
- Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, Bldg. 37, Rm.5068, NIH, Bethesda, MD, 20892-4255, USA
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Chen S, Qu X, Wan P, Li QW, Wang Z, Guo F, Bai L, Hu Z, Tan W, Li J. Norcantharidin inhibits pre-replicative complexes assembly of HepG2 cells. THE AMERICAN JOURNAL OF CHINESE MEDICINE 2013; 41:665-82. [PMID: 23711148 DOI: 10.1142/s0192415x13500468] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Norcantharidin (NCTD) is currently used for anticancer therapy but the exact mechanism of action remains unknown. Pre-replicative complexes (pre-RCs) are essential for cell DNA replication and highly related to malignant proliferation. Here, we examined the inhibitory effect of NCTD on pre-RC components in HepG2 cells. We showed that NCTD induced degradation of Cdc6 and Mcm2 in a dose-dependent manner. Under 100 μM NCTD concentration, about 70% of Cdc6 and 50% of Mcm2 were degraded. In addition, the nuclear translocation of Mcm6 was inhibited by NCTD. Further studies aiming at G1 synchronous cells showed that, NCTD reduced the chromatin-bound Cdc6, Mcm2 and Mcm6. Moreover, the cells were blocked from entering the S phase and accumulated at the G1 phase when released synchronously into the cell cycle. Consistently, the DNA replication was inhibited by NCTD. Finally, the combination NCTD with Cdc6 depletion lead to more severe cytotoxicity (88%) than NCTD (52%) and Cdc6 depletion (39%) alone. A synergic cytotoxicity was observed between Cdc6 depletion and NCTD. In conclusion, our results demonstrate that NCTD inhibits pre-RC assembly; subsequently blocks the G1 to S transition; and inhibits DNA replication in HepG2 cells. Pre-RCs are an intriguing target for cancer therapy, which merits further investigations for anticancer development.
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Affiliation(s)
- Sansan Chen
- Institute of Biotherapy, School of Biotechnology, Southern Medical University, Guangzhou, China
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14
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Jeong CH, Chun KS, Kundu J, Park B. Phosphorylation of Smac by Akt promotes the caspase-3 activation during etoposide-induced apoptosis in HeLa cells. Mol Carcinog 2013; 54:83-92. [DOI: 10.1002/mc.22075] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Revised: 07/01/2013] [Accepted: 07/08/2013] [Indexed: 11/10/2022]
Affiliation(s)
- Chul-Ho Jeong
- College of Pharmacy; Keimyung University; Daegu Republic of Korea
| | - Kyung-Soo Chun
- College of Pharmacy; Keimyung University; Daegu Republic of Korea
| | - Juthika Kundu
- College of Pharmacy; Keimyung University; Daegu Republic of Korea
| | - Byoungduck Park
- College of Pharmacy; Keimyung University; Daegu Republic of Korea
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15
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Yim H, Park JW, Woo SU, Kim ST, Liu L, Lee CH, Lee SK. Phosphorylation of Cdc6 at serine 74, but not at serine 106, drives translocation of Cdc6 to the cytoplasm. J Cell Physiol 2013; 228:1221-8. [PMID: 23129444 DOI: 10.1002/jcp.24275] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2012] [Accepted: 10/19/2012] [Indexed: 11/08/2022]
Abstract
Phosphorylation-dependent cytoplasmic translocation of human Cdc6 during S phase is sufficient to control its activity after origin firing. Export from the nucleus also serves as a mechanism for preventing re-replication in mammalian cells. Phosphorylation of the CDK consensus serine residues 54, 74, and 106 has been suggested to be involved in the cytoplasmic translocation of Cdc6. To determine the relative importance of the three phosphorylation sites, we have generated Cdc6 variants by substituting one or more of the three serine residues with alanine or aspartic acid and have assessed their cytoplasmic translocation behavior. Phosphorylation of serine 74 mainly contributes to the cytoplasmic translocation of Cdc6, while serine 54 phosphorylation provides a minor contribution. In contrast, phosphorylation at serine 106 does not affect the nuclear export of Cdc6. Comparative results were found in cells coexpressing the phosphorylation defective mutants of Cdc6 and cyclin A as well as in non-transfected cells synchronized by their release from a double thymidine block. We conclude that Cdk-mediated phosphorylation of Cdc6 at serine 74 is required for the cytoplasmic translocalization of Cdc6 during the cell cycle. Phosphorylation of Cdc6 at serine 54 plays a minor role and phosphorylation of serine 106 plays no role in the cytoplasmic localization of Cdc6. The phosphorylation of S74 in Cdc6 could be important for binding to the nuclear export protein for translocalization.
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Affiliation(s)
- Hyungshin Yim
- Division of Pharmaceutical Biosciences, Research Institute for Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Seoul, Republic of Korea.
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16
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Martin DDO, Ahpin CY, Heit RJ, Perinpanayagam MA, Yap MC, Veldhoen RA, Goping IS, Berthiaume LG. Tandem reporter assay for myristoylated proteins post‐translationally (TRAMPP) identifies novel substrates for post‐translational myristoylation: PKC∊, a case study. FASEB J 2011; 26:13-28. [DOI: 10.1096/fj.11-182360] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- Dale D. O. Martin
- Department of Cell Biology, School of Molecular and Systems MedicineFaculty of Medicine and Dentistry, University of Alberta Edmonton Alberta Canada
| | - Chrisselle Y. Ahpin
- Department of Cell Biology, School of Molecular and Systems MedicineFaculty of Medicine and Dentistry, University of Alberta Edmonton Alberta Canada
| | - Ryan J. Heit
- Department of Cell Biology, School of Molecular and Systems MedicineFaculty of Medicine and Dentistry, University of Alberta Edmonton Alberta Canada
| | - Maneka A. Perinpanayagam
- Department of Cell Biology, School of Molecular and Systems MedicineFaculty of Medicine and Dentistry, University of Alberta Edmonton Alberta Canada
| | - Megan C. Yap
- Department of Cell Biology, School of Molecular and Systems MedicineFaculty of Medicine and Dentistry, University of Alberta Edmonton Alberta Canada
| | - Richard A. Veldhoen
- Department of Biochemistry, School of Molecular and Systems MedicineFaculty of Medicine and Dentistry, University of Alberta Edmonton Alberta Canada
| | - Ing Swie Goping
- Department of Biochemistry, School of Molecular and Systems MedicineFaculty of Medicine and Dentistry, University of Alberta Edmonton Alberta Canada
| | - Luc G. Berthiaume
- Department of Cell Biology, School of Molecular and Systems MedicineFaculty of Medicine and Dentistry, University of Alberta Edmonton Alberta Canada
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17
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Xiong XD, Zeng LQ, Xiong QY, Lu SX, Zhang ZZ, Luo XP, Liu XG. Association between the CDC6 G1321A polymorphism and the risk of cervical cancer. Int J Gynecol Cancer 2010; 20:856-61. [PMID: 20606534 DOI: 10.1111/igc.0b013e3181df3cab] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
INTRODUCTION Cell division cycle protein 6 (CDC6) plays critical roles in DNA replication and carcinogenesis. The biological significance of the CDC6 G1321A polymorphism (V441I, rs13706) on cervical carcinogenesis is still unknown. Here, we examined the potential influence of this polymorphism on cell proliferation and the individual's susceptibility to cervical cancer. METHODS We genotyped the CDC6 G1321A polymorphism in 87 cervical cancer cases and 110 healthy female subjects. Unconditional logistic regression analysis was used to estimate the association between the genotypes and the risk of cervical cancer. The BrdU incorporation assay was applied to analyze the effect of this polymorphism on cell proliferation. RESULTS Compared with the GG homozygotes, the cervical cancer risk was significantly reduced in the individuals with the heterozygous AG genotype (odds ratio [OR], 0.53; 95% confidence interval [CI], 0.28-0.98; P = 0.042) or the homozygous AA genotype (OR, 0.29; 95% CI, 0.09-0.89; P = 0.030). Further stratified analyses showed that the decreased risk of cervical cancer was more evident among younger subjects (≤44 years old) with the AG or AA genotypes (OR, 0.44; 95% CI, 0.21-0.92; P = 0.029 and OR, 0.12; 95% CI, 0.03-0.61; P = 0.010, respectively). The BrdU incorporation assay showed that 293T cells transfected with CDC6-441I (1321A) had a lower proliferation rate in comparison with those transfected with CDC6-441V (1321G), although the difference did not reach statistical significance at the 0.05 level. CONCLUSIONS The CDC6 G1321A polymorphism may contribute to the risk of cervical cancer. Further studies with more subjects and in diverse ethnic populations are necessary to confirm the general validity of our findings.
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Affiliation(s)
- Xing-Dong Xiong
- Department of Biochemistry and Molecular Biology, Guangdong Medical College, Dongguan, China
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18
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Tissue-spanning redox gradient-dependent assembly of native human papillomavirus type 16 virions. J Virol 2009; 83:10515-26. [PMID: 19656879 DOI: 10.1128/jvi.00731-09] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Papillomavirus capsids are composed of 72 pentamers reinforced through inter- and intrapentameric disulfide bonds. Recent research suggests that virus-like particles and pseudovirions (PsV) can undergo a redox-dependent conformational change involving disulfide interactions. We present here evidence that native virions exploit a tissue-spanning redox gradient that facilitates assembly events in the context of the complete papillomavirus life cycle. DNA encapsidation and infectivity titers are redox dependent in that they can be temporally modulated via treatment of organotypic cultures with oxidized glutathione. These data provide evidence that papillomavirus assembly and maturation is redox-dependent, utilizing multiple steps within both suprabasal and cornified layers.
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19
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Hasegawa M, Kurata M, Yamamoto K, Yoshida K, Aizawa S, Kitagawa M. A novel role for acinus and MCM2 as host-specific signaling enhancers of DNA-damage-induced apoptosis in association with viral protein gp70. Leuk Res 2009; 33:1100-7. [DOI: 10.1016/j.leukres.2008.10.025] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2008] [Revised: 09/22/2008] [Accepted: 10/27/2008] [Indexed: 12/13/2022]
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20
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Yim H, Erikson RL. Polo-like kinase 1 depletion induces DNA damage in early S prior to caspase activation. Mol Cell Biol 2009; 29:2609-21. [PMID: 19289504 PMCID: PMC2682042 DOI: 10.1128/mcb.01277-08] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2008] [Revised: 09/22/2008] [Accepted: 03/04/2009] [Indexed: 11/20/2022] Open
Abstract
Polo-like kinase 1 (Plk1) plays several roles in mitosis, and it has been suggested to have a role in tumorigenesis. We have previously reported that Plk1 depletion results in cell death in cancer cells, whereas normal cells survive similar depletion. However, Plk1 depletion together with p53 depletion induces cell death in normal cells as well. This communication presents evidence on the sequence of events that leads to cell death in cancer cells. DNA damage is detected at the first S phase following Plk1 depletion and is more severe in Plk1-depleted p53-null cancer cells. As a consequence of Plk1 depletion using lentivirus-based small interfering RNA techniques, prereplicative complex (pre-RC) formation is disrupted at the G(1)/S transition, and DNA synthesis is reduced during S phase of the first cycle after depletion. The levels of geminin, an inhibitor of DNA pre-RC, and Emi1, an inhibitor of anaphase-promoting complex/cyclosome, are elevated in Plk1-depleted cells. The rate of cell cycling is slower in Plk1-depleted cells than in control cells when synchronized by serum starvation. Plk1 depletion results in disrupted DNA pre-RC formation, reduced DNA synthesis, and DNA damage before cells display severe mitotic catastrophe or apoptosis. Our data suggest that Plk1 is required for cell cycle progression not only in mitosis but also for DNA synthesis, maintenance of DNA integrity, and prevention of cell death.
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Affiliation(s)
- Hyungshin Yim
- Department of Molecular and Cellular Biology, Harvard University, 16 Divinity Ave., Cambridge, MA 02138, USA.
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21
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Takabatake N, Toriyama S, Igarashi A, Tokairin Y, Takeishi Y, Konta T, Inoue S, Abe S, Shibata Y, Kubota I. A novel polymorphism in CDC6 is associated with the decline in lung function of ex-smokers in COPD. Biochem Biophys Res Commun 2009; 381:554-9. [DOI: 10.1016/j.bbrc.2009.02.080] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2009] [Accepted: 02/17/2009] [Indexed: 10/21/2022]
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22
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Liu L, Choi JH, Yim H, Choi JS, Park BD, Cho SJ, Lee SK. ATR (AT mutated Rad3 related) activity stabilizes Cdc6 and delays G2/M-phase entry during hydroxyurea-induced S-phase arrest of HeLa cells. Int J Biochem Cell Biol 2008; 41:1410-20. [PMID: 19154794 DOI: 10.1016/j.biocel.2008.12.014] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2008] [Revised: 12/10/2008] [Accepted: 12/10/2008] [Indexed: 11/18/2022]
Abstract
The Cdc6 protein, a key DNA replication initiation factor, contributes to the long-term maintenance of the S-phase checkpoint by anchoring the Rad3-Rad26 complex to chromatin. Here, we demonstrate that ATR (AT mutated and Rad3 related) activity is essential for maintaining high chromatin levels of the Cdc6 protein, thereby delaying entry into mitosis during hydroxyurea (HU)-induced S-phase arrest of HeLa cells. Downregulation of ATR (AT mutated and Rad3 related) (i.e., using ATR-siRNA) reduced the protein levels of chromatin Cdc6 and significantly increased the cellular levels of phospho-histone H3 (Ser 10), an index of mitosis. Downregulation of Cdc6 was completely restored by pretreatment with MG132, a proteasome inhibitor. Moreover, mitotic entry of MG132-pretreated cells was significantly downregulated. Our results also show that ATR (AT mutated and Rad3 related) kinase phosphorylates Cdc6 at serine residue 6. Thus, this ATR (AT mutated and Rad3 related)-mediated phosphorylation of Cdc6 is likely associated with stabilization of Cdc6 protein, thereby maintaining high levels of chromatin Cdc6 and delaying premature mitotic entry. This novel mechanism likely contributes to the functional regulation of chromatin Cdc6, which delays the cell cycle of hydroxyurea-induced cells to enter mitosis at the S-phase checkpoint.
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Affiliation(s)
- Linhua Liu
- Division of Pharmaceutical Biosciences, Research Institute for Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Seoul 151-742, Republic of Korea.
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23
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Xiong XD, Qiu FE, Fang JH, Shen Y, Liang C, Jiang W, Zhuang SM. Association analysis between the Cdc6 G1321A polymorphism and the risk for non-Hodgkin lymphoma and hepatocellular carcinoma. Mutat Res 2008; 662:10-5. [PMID: 19101572 DOI: 10.1016/j.mrfmmm.2008.11.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2008] [Revised: 10/28/2008] [Accepted: 11/21/2008] [Indexed: 12/20/2022]
Abstract
Cdc6 play crucial roles in DNA replication and carcinogenesis. The biological significance of the Cdc6 G1321A polymorphism (V441I, rs13706) is still not elucidated. Here we examined the influence of this polymorphism on the function of Cdc6 and the individual's susceptibility to non-Hodgkin lymphoma (NHL) and hepatocellular carcinoma (HCC). Unconditional logistic regression analysis revealed that the risk for NHL was significantly reduced in both AG heterozygotes [odds ratio (OR)=0.67, P=0.019] and AA homozygotes (OR=0.54, P=0.026), compared with GG homozygotes. Further stratification by subtypes of NHL showed that the AG as well as combined AA/AG genotypes were associated with decreased risk for B-cell-NHL (OR=0.62, P=0.011 and OR=0.61, P=0.006, respectively), especially for diffuse large B-cell lymphoma (DLBCL, OR=0.63, P=0.025 and OR=0.62, P=0.012, respectively). In addition, male individuals with the AA genotype displayed borderline significantly reduced risk for HCC (OR=0.48, P=0.054). Interestingly, the G1321A polymorphism did not affect caspase-mediated cleavage of Cdc6 during etoposide-induced apoptosis, but it was predicted to alter the secondary structure of Cdc6 mRNA. Our data provide the first evidence that the Cdc6 G1321A polymorphism is associated with decreased risk of cancer. Further studies are necessary to confirm the general validity of our findings.
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Affiliation(s)
- Xing-Dong Xiong
- Key Laboratory of Gene Engineering of the Ministry of Education, School of Life Sciences, Sun Yat-Sen University, Guangzhou, PR China
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A caspase-dependent cleavage of CDC25A generates an active fragment activating cyclin-dependent kinase 2 during apoptosis. Cell Death Differ 2008; 16:208-18. [PMID: 18927589 DOI: 10.1038/cdd.2008.142] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The cellular level of the CDC25A phosphatase is tightly regulated during both the normal and genotoxic-perturbed cell cycle. Here, we describe a caspase-dependent cleavage of this protein at residue D223 in non-genotoxic apoptotic conditions. This specific proteolysis generates a catalytically active C-terminal fragment that localizes to the nuclear compartment. Accumulation of this active CDC25A fragment leads to reduced inhibitory phosphorylation of the CDC25A substrate cyclin-dependent kinase 2 (CDK2) on Tyr15. Moreover, CDK2 was found stably associated with this fragment, as well as with an ectopically expressed CDC25A224-525 truncation mutant that mimicks the cleavage product. Ectopic expression of this mutant induced CDK2 Tyr15 dephosphorylation, whereas its catalytically inactive version did not. Finally, this 224-525 mutant initiated apoptosis when transfected into HeLa cells, whereas its catalytic inactive form did not. Altogether, this study demonstrates for the first time that caspase-dependent cleavage of CDC25A is a central step linking CDK2 activation with non-genotoxic apoptotic induction.
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Generation of an indestructible cyclin B1 by caspase-6-dependent cleavage during mitotic catastrophe. Oncogene 2008; 28:170-83. [PMID: 18820706 DOI: 10.1038/onc.2008.369] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Overriding the G(2) DNA damage checkpoint permits precocious entry into mitosis that ultimately leads to mitotic catastrophe. Mitotic catastrophe is manifested by an unscheduled activation of CDK1, caspase activation and apoptotic cell death. We found that although cyclin B1 was required for mitotic catastrophe, it was cleaved into a approximately 35 kDa protein by a caspase-dependent mechanism during the process. Cyclin B1 cleavage occurred after Asp123 in the motif ILVD(123) downward arrow, and mutation of this motif attenuated the cleavage. Cleavage was abolished by a pan-caspase inhibitor as well as by specific inhibitors for the effector caspase-6 and the initiator caspase-8. Cleavage created a truncated cyclin B1 lacking part of the NH(2)-terminal regulatory domain that included the destruction box sequence. Although cleavage of cyclin B1 itself was not absolutely required for mitotic catastrophe, expression of the truncated product enhanced cell death. In support of this, ectopic expression of this truncated cyclin B1 was not only sufficient to induce mitotic block and apoptosis but also enhanced mitotic catastrophe induced by ionizing radiation and caffeine. These data underscore a possible linkage between mitotic and apoptotic functions by caspase-dependent processing of mitotic activators.
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26
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Cleavage of phospholipase D1 by caspase promotes apoptosis via modulation of the p53-dependent cell death pathway. Cell Death Differ 2008; 15:1782-93. [PMID: 18636075 DOI: 10.1038/cdd.2008.111] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The enzymatic activity of phospholipase D (PLD) is known to be essential for cell survival and protection from apoptosis. However, the mechanisms regulating PLD activity during apoptosis remain unknown. Here we report that cleavage of PLD1 by caspases facilitates p53-mediated apoptosis. Cleavage of PLD1 into an N-terminal fragment (NF-PLD1) and a C-terminal fragment at the amino-acid sequence, DDVD(545), led to a reduction in PLD1 activity. However, a caspase-resistant mutant form of PLD1 retained significant levels of enzymatic activity and apoptotic function as compared to wild-type PLD1. Exogenous NF-PLD1 expression induced apoptosis through a dominant-negative effect on the activity of endogenous PLD1. During apoptosis, a small fraction of PLD1 is cleaved by caspases in a p53-independent manner and NF-PLD1 amplifies apoptotic signaling through inhibition of the remaining PLD1 activity. As PLD1 suppresses the ATM-Chk2-p53 pathway, elimination of PLD1 activity through NF-PLD1 or si-RNA against PLD1 increases apoptosis in a p53-dependent manner. Taken together, our results reveal that cleavage of PLD1 by caspases promotes apoptosis via modulation of the p53-dependent cell death pathway.
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27
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Xiong XD, Fang JH, Qiu FE, Zhao J, Cheng J, Yuan Y, Li SP, Zhuang SM. A novel functional polymorphism in the Cdc6 promoter is associated with the risk for hepatocellular carcinoma. Mutat Res 2008; 643:70-4. [PMID: 18640135 DOI: 10.1016/j.mrfmmm.2008.06.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2008] [Revised: 06/06/2008] [Accepted: 06/19/2008] [Indexed: 11/25/2022]
Abstract
Cdc6 is essential for DNA replication and its deregulation is involved in carcinogenesis. To date, the biological significance of the polymorphism in Cdc6 promoter is still unknown. In this study, we aimed to evaluate the influence of the Cdc6 -515A>G polymorphism (rs4134994) on the individual's susceptibility to cancer and on the function of Cdc6. The Cdc6 -515A>G polymorphism was genotyped in 387 hepatocellular carcinoma (HCC) and 389 age- and sex-matched healthy subjects. The association between the genotypes and the risk for HCC was then estimated by unconditional logistic regression analysis with adjustment for age, sex and HBV status. Compared with the AA homozygotes, the homozygous GG genotype (adjusted OR=0.36, 95% confidence interval (CI)=0.18-0.72, P=0.004) or the combined AG/GG genotypes (adjusted OR=0.56, 95% CI=0.36-0.86, P=0.008) were statistically significantly associated with the reduced risk for HCC. Moreover, the analysis using luciferase reporter system showed that the G-allelic Cdc6 promoter displayed a decreased transcriptional activity compared with the A-allelic one. These results indicate that the individuals with G allele may have reduced Cdc6 expression and are therefore in reduced risk for HCC. Further investigation using electrophoretic mobility shift assay (EMSA) revealed that the G allele had a stronger binding strength to nuclear protein(s) which might function as negative regulator(s) for Cdc6 transcription. Our findings suggest that the -515A>G polymorphism may affect the Cdc6 promoter binding affinity with nuclear protein(s) and in turn the Cdc6 expression, which consequently modulates the individual's susceptibility to HCC.
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Affiliation(s)
- Xing-Dong Xiong
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-Sen University, Guangzhou, PR China
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28
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Hook SS, Lin JJ, Dutta A. Mechanisms to control rereplication and implications for cancer. Curr Opin Cell Biol 2007; 19:663-71. [PMID: 18053699 DOI: 10.1016/j.ceb.2007.10.007] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2007] [Revised: 10/11/2007] [Accepted: 10/11/2007] [Indexed: 12/19/2022]
Abstract
Recent advances in the replication field have highlighted how the replication initiator proteins are negatively regulated by inhibitor proteins and ubiquitin-mediated degradation in mammalian cells to prevent rereplication. When these regulatory pathways go awry, uncontrolled rereplication ensues and a G2/M checkpoint is evoked to prevent cellular death. Many components of the checkpoints activated by rereplicaton are important for cancer prevention by facilitating DNA damage repair processes. The pathways that prevent rereplication themselves have also recently been implicated in preventing tumorigenesis. Studies from patient tumors, genetically altered mice, and mammalian cell culture suggest that deregulation of replication licensing proteins results in an increase in aneuploidy, chromosomal fusions, and DNA breaks. These studies provide a framework to address how regulators of replication function to maintain genomic stability.
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Affiliation(s)
- Sara S Hook
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA 22908, USA.
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