1
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Forey R, Poveda A, Sharma S, Barthe A, Padioleau I, Renard C, Lambert R, Skrzypczak M, Ginalski K, Lengronne A, Chabes A, Pardo B, Pasero P. Mec1 Is Activated at the Onset of Normal S Phase by Low-dNTP Pools Impeding DNA Replication. Mol Cell 2020; 78:396-410.e4. [PMID: 32169162 DOI: 10.1016/j.molcel.2020.02.021] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Revised: 01/09/2020] [Accepted: 02/24/2020] [Indexed: 10/24/2022]
Abstract
The Mec1 and Rad53 kinases play a central role during acute replication stress in budding yeast. They are also essential for viability in normal growth conditions, but the signal that activates the Mec1-Rad53 pathway in the absence of exogenous insults is currently unknown. Here, we show that this pathway is active at the onset of normal S phase because deoxyribonucleotide triphosphate (dNTP) levels present in G1 phase may not be sufficient to support processive DNA synthesis and impede DNA replication. This activation can be suppressed experimentally by increasing dNTP levels in G1 phase. Moreover, we show that unchallenged cells entering S phase in the absence of Rad53 undergo irreversible fork collapse and mitotic catastrophe. Together, these data indicate that cells use suboptimal dNTP pools to detect the onset of DNA replication and activate the Mec1-Rad53 pathway, which in turn maintains functional forks and triggers dNTP synthesis, allowing the completion of DNA replication.
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Affiliation(s)
- Romain Forey
- Institut de Génétique Humaine, CNRS, Université de Montpellier, Montpellier, France
| | - Ana Poveda
- Institut de Génétique Humaine, CNRS, Université de Montpellier, Montpellier, France; Instituto de Investigación en Salud Pública y Zoonosis, Facultad de Ciencias Químicas, Universidad Central del Ecuador, Quito, Ecuador
| | - Sushma Sharma
- Department of Medical Biochemistry and Biophysics and Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Umeå, Sweden
| | - Antoine Barthe
- Institut de Génétique Humaine, CNRS, Université de Montpellier, Montpellier, France
| | - Ismael Padioleau
- Institut de Génétique Humaine, CNRS, Université de Montpellier, Montpellier, France
| | - Claire Renard
- Institut de Génétique Humaine, CNRS, Université de Montpellier, Montpellier, France
| | - Robin Lambert
- Institut de Génétique Humaine, CNRS, Université de Montpellier, Montpellier, France
| | - Magdalena Skrzypczak
- Laboratory of Bioinformatics and Systems Biology, Centre of New Technologies, University of Warsaw, Zwirki i Wigury 93, 02-089 Warsaw, Poland
| | - Krzysztof Ginalski
- Laboratory of Bioinformatics and Systems Biology, Centre of New Technologies, University of Warsaw, Zwirki i Wigury 93, 02-089 Warsaw, Poland
| | - Armelle Lengronne
- Institut de Génétique Humaine, CNRS, Université de Montpellier, Montpellier, France
| | - Andrei Chabes
- Department of Medical Biochemistry and Biophysics and Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Umeå, Sweden
| | - Benjamin Pardo
- Institut de Génétique Humaine, CNRS, Université de Montpellier, Montpellier, France.
| | - Philippe Pasero
- Institut de Génétique Humaine, CNRS, Université de Montpellier, Montpellier, France.
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2
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Ovejero S, Bueno A, Sacristán MP. Working on Genomic Stability: From the S-Phase to Mitosis. Genes (Basel) 2020; 11:E225. [PMID: 32093406 PMCID: PMC7074175 DOI: 10.3390/genes11020225] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Revised: 02/17/2020] [Accepted: 02/18/2020] [Indexed: 12/15/2022] Open
Abstract
Fidelity in chromosome duplication and segregation is indispensable for maintaining genomic stability and the perpetuation of life. Challenges to genome integrity jeopardize cell survival and are at the root of different types of pathologies, such as cancer. The following three main sources of genomic instability exist: DNA damage, replicative stress, and chromosome segregation defects. In response to these challenges, eukaryotic cells have evolved control mechanisms, also known as checkpoint systems, which sense under-replicated or damaged DNA and activate specialized DNA repair machineries. Cells make use of these checkpoints throughout interphase to shield genome integrity before mitosis. Later on, when the cells enter into mitosis, the spindle assembly checkpoint (SAC) is activated and remains active until the chromosomes are properly attached to the spindle apparatus to ensure an equal segregation among daughter cells. All of these processes are tightly interconnected and under strict regulation in the context of the cell division cycle. The chromosomal instability underlying cancer pathogenesis has recently emerged as a major source for understanding the mitotic processes that helps to safeguard genome integrity. Here, we review the special interconnection between the S-phase and mitosis in the presence of under-replicated DNA regions. Furthermore, we discuss what is known about the DNA damage response activated in mitosis that preserves chromosomal integrity.
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Affiliation(s)
- Sara Ovejero
- Instituto de Biología Molecular y Celular del Cáncer (IBMCC), Universidad de Salamanca-CSIC, Campus Miguel de Unamuno, 37007 Salamanca, Spain
- Institute of Human Genetics, CNRS, University of Montpellier, 34000 Montpellier, France
- Department of Biological Hematology, CHU Montpellier, 34295 Montpellier, France
| | - Avelino Bueno
- Instituto de Biología Molecular y Celular del Cáncer (IBMCC), Universidad de Salamanca-CSIC, Campus Miguel de Unamuno, 37007 Salamanca, Spain
- Departamento de Microbiología y Genética, Universidad de Salamanca, Campus Miguel de Unamuno, 37007 Salamanca, Spain
| | - María P. Sacristán
- Instituto de Biología Molecular y Celular del Cáncer (IBMCC), Universidad de Salamanca-CSIC, Campus Miguel de Unamuno, 37007 Salamanca, Spain
- Departamento de Microbiología y Genética, Universidad de Salamanca, Campus Miguel de Unamuno, 37007 Salamanca, Spain
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3
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Liu C, Nie J, Wang R, Mao W. The Cell Cycle G2/M Block Is an Indicator of Cellular Radiosensitivity. Dose Response 2019; 17:1559325819891008. [PMID: 31839758 PMCID: PMC6902394 DOI: 10.1177/1559325819891008] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Revised: 10/28/2019] [Accepted: 10/29/2019] [Indexed: 01/06/2023] Open
Abstract
Background: Determination of the radiosensitivity of a specific tumor is essential to its precision tumor radiotherapy, but the measurement of cellular radiosensitivity with a routine colony forming assay is both labor- and time-consuming. An alternative option allowing rapid and precise prediction of radiosensitivity is necessary. Methods: In this study, we exposed 4 in vitro cultured cell lines to various doses of X-rays or carbon ions and then measured their radiosensitivities with a routine colony-forming assay, and monitored the kinetics of cell cycle distribution with routine propidium iodine staining and flow cytometry. Results: Based on the results, we correlated cellular radiosensitivity with a dynamic assay of cell cycle distribution, specifically, the negative correlation of cellular radiosensitivity with the accumulated G2/M arrested cells at 48 hours after exposure. The higher the proportion of accumulated G2/M arrested cells at 48 hours after exposure, the lower the radiosensitivity of the cell line, that is, the higher radioresistance of the cell line. Conclusion: These findings provide an optional application of regular cell cycle analysis for the prediction of tumor radiosensitivity.
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Affiliation(s)
- Chang Liu
- Department of Radiotherapy, the First Affiliated Hospital of Guangxi Medical University, Nanning, China
| | - Jing Nie
- State Key Laboratory of Radiation Medicine and Protection, School of Radiation Medicine and Protection, Medical College of Soochow University, Suzhou, China.,Collaborative Innovation Center of Radiological Medicine of Jiangsu Higher Education Institutions, Suzhou, China
| | - Rensheng Wang
- Department of Radiotherapy, the First Affiliated Hospital of Guangxi Medical University, Nanning, China
| | - Weidong Mao
- State Key Laboratory of Radiation Medicine and Protection, School of Radiation Medicine and Protection, Medical College of Soochow University, Suzhou, China.,Department of Radiotherapy & Oncology, The Second Affiliated Hospital of Soochow University, Suzhou, China
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4
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Lanz MC, Dibitetto D, Smolka MB. DNA damage kinase signaling: checkpoint and repair at 30 years. EMBO J 2019; 38:e101801. [PMID: 31393028 PMCID: PMC6745504 DOI: 10.15252/embj.2019101801] [Citation(s) in RCA: 151] [Impact Index Per Article: 30.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Revised: 07/03/2019] [Accepted: 07/24/2019] [Indexed: 12/27/2022] Open
Abstract
From bacteria to mammalian cells, damaged DNA is sensed and targeted by DNA repair pathways. In eukaryotes, kinases play a central role in coordinating the DNA damage response. DNA damage signaling kinases were identified over two decades ago and linked to the cell cycle checkpoint concept proposed by Weinert and Hartwell in 1988. Connections between the DNA damage signaling kinases and DNA repair were scant at first, and the initial perception was that the importance of these kinases for genome integrity was largely an indirect effect of their roles in checkpoints, DNA replication, and transcription. As more substrates of DNA damage signaling kinases were identified, it became clear that they directly regulate a wide range of DNA repair factors. Here, we review our current understanding of DNA damage signaling kinases, delineating the key substrates in budding yeast and humans. We trace the progress of the field in the last 30 years and discuss our current understanding of the major substrate regulatory mechanisms involved in checkpoint responses and DNA repair.
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Affiliation(s)
- Michael Charles Lanz
- Department of Molecular Biology and GeneticsWeill Institute for Cell and Molecular BiologyCornell UniversityIthacaNYUSA
| | - Diego Dibitetto
- Department of Molecular Biology and GeneticsWeill Institute for Cell and Molecular BiologyCornell UniversityIthacaNYUSA
| | - Marcus Bustamante Smolka
- Department of Molecular Biology and GeneticsWeill Institute for Cell and Molecular BiologyCornell UniversityIthacaNYUSA
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5
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Zhu L, Wang Q, Hu Y, Wang F. The Circadian Gene Per1 Plays an Important Role in Radiation-Induced Apoptosis and DNA Damage in Glioma. Asian Pac J Cancer Prev 2019; 20:2195-2201. [PMID: 31350984 PMCID: PMC6745214 DOI: 10.31557/apjcp.2019.20.7.2195] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Indexed: 01/27/2023] Open
Abstract
Objective: Period1 (PER1), a core circadian gene, not only modulates circadian rhythm but may also play an important role in other biological processes, including pathways involved in the proliferation and apoptosis of tumor cells. In this study, we investigated the mechanism by which the downregulated expression of PER1 promotes the apoptosis of wild-type P53 human glioma U343 cells exposed to X-rays. Methods: U343 cells were exposed to 6 mV 10 Gy X-ray irradiation after infection with an shRNA lentivirus to reduce the expression of PER1 and were analyzed by SCGE analysis, flow cytometry, qRT-PCR, and western blotting. Result: SCGE analysis revealed that compared with the controls, U343 cells expressing low levels of PER1 showed minor DNA damage when exposed to X-ray irradiation (P<0.05), and the flow cytometry assay showed lower death rates (P<0.05). RT-PCR and western blot analysis both revealed decreased expression of CHK2 and P53, which regulate DNA damage and repair via the CHK2-P53 pathway, and decreased expression of C-MYC, which is related to cell apoptosis. Conclusion: Our research suggests that PER1 may play an important role in tumor radiotherapy, which is attributable to enhanced chk2-P53 signaling and proapoptotic processes. These findings provide a new target for the clinical treatment of glioma and a reliable basis for postradiation therapy and gene therapy for glioma and other cancers.
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Affiliation(s)
- Ling Zhu
- Department of Neurosurgery, The First People's Hospital of Jingmen, Jingmen, China.
| | - Qunli Wang
- Department of Neurosurgery, The Second People's Hospital of Jingmen, Jingmen, China
| | - Yi Hu
- Department of Neurosurgery, The Second People's Hospital of Jingmen, Jingmen, China
| | - Fan Wang
- Department of Neurosurgery, The Second People's Hospital of Jingmen, Jingmen, China
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6
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Lee JY, Lim W, Ryu S, Kim J, Song G. Ochratoxin A mediates cytotoxicity through the MAPK signaling pathway and alters intracellular homeostasis in bovine mammary epithelial cells. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2019; 246:366-373. [PMID: 30577004 DOI: 10.1016/j.envpol.2018.12.032] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Revised: 11/18/2018] [Accepted: 12/11/2018] [Indexed: 06/09/2023]
Abstract
Ochratoxin A (OTA), a secondary metabolite of the genera Penicillium and Aspergillus, contaminates many types of food and causes apoptosis as well as immunosuppression in many animal species. However, a mechanistic analysis of OTA-mediated cytotoxicity in bovine mammary epithelial cells has not yet been performed. Hence, we investigated the effects of OTA on bovine mammary epithelial (MAC-T) cells using several mechanistic analyses. We report that OTA may induce cell cycle arrest and apoptosis via MAPK and JNK signaling pathways in MAC-T cells. Moreover, homeostasis of cellular components, such as that of the mitochondrial membrane, was disrupted by OTA, leading to a decrease in mitochondrial and cytosolic Ca2+ in MAC-T cells. In addition, we evaluated the effects of OTA on inflammatory responses and major tight junction regulators, such as occludin and claudin 3. In summation, we suggest that OTA contamination may adversely affect bovine mammary epithelial cells, leading to improper lactation and decreased milk quality. This article aims to improve the understanding of physiological mechanisms involved in lactation, in addition to providing a guideline for the stabilization of industrial milk production by countering exogenous contaminants in livestock.
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Affiliation(s)
- Jin-Young Lee
- Department of Pharmacy, College of Pharmacy, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 08826, Republic of Korea
| | - Whasun Lim
- Department of Biomedical Sciences, Catholic Kwandong University, Gangneung, 25601, Republic of Korea
| | - Soomin Ryu
- Institute of Animal Molecular Biotechnology and Department of Biotechnology, College of Life Sciences and Biotechnology, Korea University, Seoul, 02841, Republic of Korea
| | - Jinyoung Kim
- Department of Animal Resources Science, Dankook University, Cheonan, 330-714, Republic of Korea
| | - Gwonhwa Song
- Institute of Animal Molecular Biotechnology and Department of Biotechnology, College of Life Sciences and Biotechnology, Korea University, Seoul, 02841, Republic of Korea.
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7
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Syn NL, Lim PL, Kong LR, Wang L, Wong ALA, Lim CM, Loh TKS, Siemeister G, Goh BC, Hsieh WS. Pan-CDK inhibition augments cisplatin lethality in nasopharyngeal carcinoma cell lines and xenograft models. Signal Transduct Target Ther 2018; 3:9. [PMID: 29666673 PMCID: PMC5897350 DOI: 10.1038/s41392-018-0010-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2017] [Revised: 01/03/2018] [Accepted: 01/25/2018] [Indexed: 01/28/2023] Open
Abstract
In addition to their canonical roles in regulating cell cycle transition and transcription, cyclin-dependent kinases (CDKs) have been shown to coordinate DNA damage response pathways, suggesting a rational pairing of CDK inhibitors with genotoxic chemotherapeutic agents in the treatment of human malignancies. Here, we report that roniciclib (BAY1000394), a potent pan-CDK inhibitor, displays promising anti-neoplastic activity as a single agent and potentiates cisplatin lethality in preclinical nasopharyngeal carcinoma (NPC) models. Proliferation of the NPC cell lines HONE-1, CNE-2, C666-1, and HK-1 was effectively curbed by roniciclib treatment, with IC50 values between 11 and 38 nmol/L. These anticancer effects were mediated by pleiotropic mechanisms consistent with successful blockade of cell cycle CDKs 1, 2, 3, and 4 and transcriptional CDKs 7 and 9, ultimately resulting in arrest at G1/S and G2/M, downregulation of the transcriptional apparatus, and repression of anti-apoptotic proteins. Considerably enhanced tumor cell apoptosis was achieved following combined treatment with 10 nmol/L roniciclib and 2.0 μmol/L cisplatin; this combination therapy achieved a response over 250% greater than either drug alone. Although roniciclib chemosensitized NPC cells to cisplatin, it did not sensitize untransformed (NP69) cells. The administration of 0.5 mg/kg roniciclib to BALB/c xenograft mice was well tolerated and effectively restrained tumor growth comparable to treatment with 6 mg/kg cisplatin, whereas combining these two agents produced far greater tumor suppression than either of the monotherapies. In summary, these data demonstrate that roniciclib has strong anti-NPC activity and synergizes with cisplatin chemotherapy at clinically relevant doses, thus justifying further evaluation of this combinatorial approach in clinical settings. Nasopharyngeal carcinoma (NPC) is an uncommon malignancy arising from the nasopharynx epithelium, and is endemic to east and southeast parts of Asia where they account for 70% of worldwide incidence. Researchers from the Cancer Science Institute of Singapore examined the anti-tumor effects of roniciclib—a small-molecule drug that blocks a family of enzymes known as cyclin-dependent kinases (CDKs) which are classically involved in cell cycle progression and transcription—in cell lines and mouse models of nasopharyngeal carcinoma. Because CDK/cyclin complexes have a putative role in DNA repair, roniciclib was combined with cisplatin, a DNA-damaging agent which is currently used in chemotherapy of NPC. The authors found that roniciclib had potent anti-NPC effects when given alone, whereas the combination of roniciclib and cisplatin proved to be highly synergistic and restrained tumor growth to a greater extent than either drugs given alone. Interestingly, roniciclib appeared to selectively enhance the anti-cancer effects of cisplatin in cancerous cells while this “chemo-sensitizing” phenomenon was not seen in non-cancerous cells, suggesting that giving both drugs together could improve the effectiveness of standard chemotherapy without incurring additional toxicities. These findings suggest that roniciclib should be evaluated clinically in patients with NPC.
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Affiliation(s)
- Nicholas L Syn
- 1Cancer Science Institute of Singapore, National University of Singapore, Singapore, Singapore.,2Department of Haematology-Oncology, National University Cancer Institute, Singapore, Singapore
| | - Pei Li Lim
- 1Cancer Science Institute of Singapore, National University of Singapore, Singapore, Singapore
| | - Li Ren Kong
- 1Cancer Science Institute of Singapore, National University of Singapore, Singapore, Singapore
| | - Lingzhi Wang
- 1Cancer Science Institute of Singapore, National University of Singapore, Singapore, Singapore.,3Department of Pharmacology, Yong Loo Lin School of Medicine, National University Health System, Singapore, Singapore
| | - Andrea Li-Ann Wong
- 1Cancer Science Institute of Singapore, National University of Singapore, Singapore, Singapore.,2Department of Haematology-Oncology, National University Cancer Institute, Singapore, Singapore
| | - Chwee Ming Lim
- 4Department of Otolaryngology-Head and Neck Surgery, National University Health System, Singapore, Singapore
| | - Thomas Kwok Seng Loh
- 4Department of Otolaryngology-Head and Neck Surgery, National University Health System, Singapore, Singapore
| | | | - Boon Cher Goh
- 1Cancer Science Institute of Singapore, National University of Singapore, Singapore, Singapore.,2Department of Haematology-Oncology, National University Cancer Institute, Singapore, Singapore.,3Department of Pharmacology, Yong Loo Lin School of Medicine, National University Health System, Singapore, Singapore
| | - Wen-Son Hsieh
- 1Cancer Science Institute of Singapore, National University of Singapore, Singapore, Singapore
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8
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Ovatodiolide isolated from Anisomeles indica induces cell cycle G2/M arrest and apoptosis via a ROS-dependent ATM/ATR signaling pathways. Eur J Pharmacol 2018; 819:16-29. [DOI: 10.1016/j.ejphar.2017.09.050] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Revised: 09/24/2017] [Accepted: 09/28/2017] [Indexed: 12/23/2022]
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9
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Zhanfeng N, Chengquan W, Hechun X, Jun W, Lijian Z, Dede M, Wenbin L, Lei Y. Period2 downregulation inhibits glioma cell apoptosis by activating the MDM2-TP53 pathway. Oncotarget 2017; 7:27350-62. [PMID: 27036047 PMCID: PMC5053655 DOI: 10.18632/oncotarget.8439] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Accepted: 03/16/2016] [Indexed: 12/21/2022] Open
Abstract
The Period2 (Per2) gene is an essential component of the mammalian circadian clock and is strongly linked to glioma occurrence and its response to radiotherapy. Here, we examined the role of Per2 in the response to X-ray-induced DNA damage in U343 glioma cells and in a mouse cancer model. Following low dose X-ray irradiation, we observed that lowering Per2 expression using RNAi reduces DNA damage and cell death in U343 cells and glioma tissue. Additionally, Per2 was associated with increased TP53 activity and was involved in the DNA damage during TP53-mediated apoptosis. These findings suggest that Per2, a core circadian gene, is not only a tumor suppressor gene but can also be regarded as an upstream regulator of TP53. It thus appears that Per2 is an important inhibitor of tumor growth that acts by increasing TP53 expression, DNA damage repair, and apoptosis.
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Affiliation(s)
- Niu Zhanfeng
- Department of Neurosurgery, The General Hospital of Ningxia Medical University, Yinchuan, 750004, China.,Incubation Base of National Key Laboratory for Cerebrocranial Diseases, Ningxia Medical University, Yinchuan, 750004, China
| | - Wang Chengquan
- The People's Hospital of Liaocheng City, Liaocheng, 252000, China
| | - Xia Hechun
- Department of Neurosurgery, The General Hospital of Ningxia Medical University, Yinchuan, 750004, China.,Incubation Base of National Key Laboratory for Cerebrocranial Diseases, Ningxia Medical University, Yinchuan, 750004, China
| | - Wang Jun
- Ningxia Medical University, Yinchuan, 750004, China.,Incubation Base of National Key Laboratory for Cerebrocranial Diseases, Ningxia Medical University, Yinchuan, 750004, China
| | - Zhang Lijian
- Ningxia Medical University, Yinchuan, 750004, China.,Incubation Base of National Key Laboratory for Cerebrocranial Diseases, Ningxia Medical University, Yinchuan, 750004, China
| | - Ma Dede
- Ningxia Medical University, Yinchuan, 750004, China.,Incubation Base of National Key Laboratory for Cerebrocranial Diseases, Ningxia Medical University, Yinchuan, 750004, China
| | - Liu Wenbin
- Ningxia Medical University, Yinchuan, 750004, China.,Incubation Base of National Key Laboratory for Cerebrocranial Diseases, Ningxia Medical University, Yinchuan, 750004, China
| | - Yin Lei
- Department of ICU, The General Hospital of Ningxia Medical University, Yinchuan, 750004, China.,Incubation Base of National Key Laboratory for Cerebrocranial Diseases, Ningxia Medical University, Yinchuan, 750004, China
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10
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Lu Y, Knapp M, Crawford K, Warne R, Elling R, Yan K, Doyle M, Pardee G, Zhang L, Ma S, Mamo M, Ornelas E, Pan Y, Bussiere D, Jansen J, Zaror I, Lai A, Barsanti P, Sim J. Rationally Designed PI3Kα Mutants to Mimic ATR and Their Use to Understand Binding Specificity of ATR Inhibitors. J Mol Biol 2017; 429:1684-1704. [PMID: 28433539 DOI: 10.1016/j.jmb.2017.04.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Revised: 04/08/2017] [Accepted: 04/11/2017] [Indexed: 12/16/2022]
Abstract
ATR, a protein kinase in the PIKK family, plays a critical role in the cell DNA-damage response and is an attractive anticancer drug target. Several potent and selective inhibitors of ATR have been reported showing significant antitumor efficacy, with most advanced ones entering clinical trials. However, due to the absence of an experimental ATR structure, the determinants contributing to ATR inhibitors' potency and specificity are not well understood. Here we present the mutations in the ATP-binding site of PI3Kα to progressively transform the pocket to mimic that of ATR. The generated PI3Kα mutants exhibit significantly improved affinity for selective ATR inhibitors in multiple chemical classes. Furthermore, we obtained the X-ray structures of the PI3Kα mutants in complex with the ATR inhibitors. The crystal structures together with the analysis on the inhibitor affinity profile elucidate the roles of individual amino acid residues in the binding of ATR inhibitors, offering key insights for the binding mechanism and revealing the structure features important for the specificity of ATR inhibitors. The ability to obtain structural and binding data for these PI3Kα mutants, together with their ATR-like inhibitor binding profiles, makes these chimeric PI3Kα proteins valuable model systems for structure-based inhibitor design.
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Affiliation(s)
- Yipin Lu
- Global Discovery Chemistry, Novartis Institutes for Biomedical Research, Emeryville, CA 94608, USA.
| | - Mark Knapp
- Global Discovery Chemistry, Novartis Institutes for Biomedical Research, Emeryville, CA 94608, USA.
| | - Kenneth Crawford
- Oncology, Novartis Institutes for Biomedical Research, Emeryville, CA 94608, USA
| | - Robert Warne
- Oncology, Novartis Institutes for Biomedical Research, Emeryville, CA 94608, USA
| | - Robert Elling
- Global Discovery Chemistry, Novartis Institutes for Biomedical Research, Emeryville, CA 94608, USA
| | - Kelly Yan
- Oncology, Novartis Institutes for Biomedical Research, Emeryville, CA 94608, USA
| | - Michael Doyle
- Oncology, Novartis Institutes for Biomedical Research, Emeryville, CA 94608, USA
| | - Gwynn Pardee
- Oncology, Novartis Institutes for Biomedical Research, Emeryville, CA 94608, USA
| | - Li Zhang
- Oncology, Novartis Institutes for Biomedical Research, Emeryville, CA 94608, USA
| | - Sylvia Ma
- Oncology, Novartis Institutes for Biomedical Research, Emeryville, CA 94608, USA
| | - Mulugeta Mamo
- Global Discovery Chemistry, Novartis Institutes for Biomedical Research, Emeryville, CA 94608, USA
| | - Elizabeth Ornelas
- Global Discovery Chemistry, Novartis Institutes for Biomedical Research, Emeryville, CA 94608, USA
| | - Yue Pan
- Global Discovery Chemistry, Novartis Institutes for Biomedical Research, Emeryville, CA 94608, USA
| | - Dirksen Bussiere
- Global Discovery Chemistry, Novartis Institutes for Biomedical Research, Emeryville, CA 94608, USA
| | - Johanna Jansen
- Global Discovery Chemistry, Novartis Institutes for Biomedical Research, Emeryville, CA 94608, USA
| | - Isabel Zaror
- Oncology, Novartis Institutes for Biomedical Research, Emeryville, CA 94608, USA
| | - Albert Lai
- Oncology, Novartis Institutes for Biomedical Research, Emeryville, CA 94608, USA
| | - Paul Barsanti
- Global Discovery Chemistry, Novartis Institutes for Biomedical Research, Emeryville, CA 94608, USA
| | - Janet Sim
- Oncology, Novartis Institutes for Biomedical Research, Emeryville, CA 94608, USA
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11
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Winter M, Dokic I, Schlegel J, Warnken U, Debus J, Abdollahi A, Schnölzer M. Deciphering the Acute Cellular Phosphoproteome Response to Irradiation with X-rays, Protons and Carbon Ions. Mol Cell Proteomics 2017; 16:855-872. [PMID: 28302921 DOI: 10.1074/mcp.m116.066597] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Revised: 03/15/2017] [Indexed: 12/15/2022] Open
Abstract
Radiotherapy is a cornerstone of cancer therapy. The recently established particle therapy with raster-scanning protons and carbon ions landmarks a new era in the field of high-precision cancer medicine. However, molecular mechanisms governing radiation induced intracellular signaling remain elusive. Here, we present the first comprehensive proteomic and phosphoproteomic study applying stable isotope labeling by amino acids in cell culture (SILAC) in combination with high-resolution mass spectrometry to decipher cellular response to irradiation with X-rays, protons and carbon ions. At protein expression level limited alterations were observed 2 h post irradiation of human lung adenocarcinoma cells. In contrast, 181 phosphorylation sites were found to be differentially regulated out of which 151 sites were not hitherto attributed to radiation response as revealed by crosscheck with the PhosphoSitePlus database.Radiation-induced phosphorylation of the p(S/T)Q motif was the prevailing regulation pattern affecting proteins involved in DNA damage response signaling. Because radiation doses were selected to produce same level of cell kill and DNA double-strand breakage for each radiation quality, DNA damage responsive phosphorylation sites were regulated to same extent. However, differential phosphorylation between radiation qualities was observed for 55 phosphorylation sites indicating the existence of distinct signaling circuitries induced by X-ray versus particle (proton/carbon) irradiation beyond the canonical DNA damage response. This unexpected finding was confirmed in targeted spike-in experiments using synthetic isotope labeled phosphopeptides. Herewith, we successfully validated uniform DNA damage response signaling coexisting with altered signaling involved in apoptosis and metabolic processes induced by X-ray and particle based treatments.In summary, the comprehensive insight into the radiation-induced phosphoproteome landscape is instructive for the design of functional studies aiming to decipher cellular signaling processes in response to radiotherapy, space radiation or ionizing radiation per se Further, our data will have a significant impact on the ongoing debate about patient treatment modalities.
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Affiliation(s)
- Martin Winter
- From the ‡Functional Proteome Analysis, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 580, D-69120 Heidelberg, Germany.,§Translational Radiation Oncology, National Center for Tumor diseases (NCT), German Cancer Research Center (DKFZ), Im Neuenheimer Feld 460, D-69120 Heidelberg, Germany.,¶German Cancer Consortium (DKTK), Heidelberg, Germany
| | - Ivana Dokic
- §Translational Radiation Oncology, National Center for Tumor diseases (NCT), German Cancer Research Center (DKFZ), Im Neuenheimer Feld 460, D-69120 Heidelberg, Germany.,¶German Cancer Consortium (DKTK), Heidelberg, Germany.,‖Heidelberg Ion Beam Therapy Center (HIT), Department of Radiation Oncology, University of Heidelberg Medical School, Im Neuenheimer Feld 450, D-69120 Heidelberg, Germany.,**Heidelberg Institute of Radiation Oncology (HIRO), National Center for Radiation Research in Oncology (NCRO), Heidelberg, Germany
| | - Julian Schlegel
- §Translational Radiation Oncology, National Center for Tumor diseases (NCT), German Cancer Research Center (DKFZ), Im Neuenheimer Feld 460, D-69120 Heidelberg, Germany.,¶German Cancer Consortium (DKTK), Heidelberg, Germany.,‖Heidelberg Ion Beam Therapy Center (HIT), Department of Radiation Oncology, University of Heidelberg Medical School, Im Neuenheimer Feld 450, D-69120 Heidelberg, Germany.,**Heidelberg Institute of Radiation Oncology (HIRO), National Center for Radiation Research in Oncology (NCRO), Heidelberg, Germany
| | - Uwe Warnken
- From the ‡Functional Proteome Analysis, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 580, D-69120 Heidelberg, Germany
| | - Jürgen Debus
- §Translational Radiation Oncology, National Center for Tumor diseases (NCT), German Cancer Research Center (DKFZ), Im Neuenheimer Feld 460, D-69120 Heidelberg, Germany.,¶German Cancer Consortium (DKTK), Heidelberg, Germany.,‖Heidelberg Ion Beam Therapy Center (HIT), Department of Radiation Oncology, University of Heidelberg Medical School, Im Neuenheimer Feld 450, D-69120 Heidelberg, Germany.,**Heidelberg Institute of Radiation Oncology (HIRO), National Center for Radiation Research in Oncology (NCRO), Heidelberg, Germany
| | - Amir Abdollahi
- §Translational Radiation Oncology, National Center for Tumor diseases (NCT), German Cancer Research Center (DKFZ), Im Neuenheimer Feld 460, D-69120 Heidelberg, Germany.,¶German Cancer Consortium (DKTK), Heidelberg, Germany.,‖Heidelberg Ion Beam Therapy Center (HIT), Department of Radiation Oncology, University of Heidelberg Medical School, Im Neuenheimer Feld 450, D-69120 Heidelberg, Germany.,**Heidelberg Institute of Radiation Oncology (HIRO), National Center for Radiation Research in Oncology (NCRO), Heidelberg, Germany
| | - Martina Schnölzer
- From the ‡Functional Proteome Analysis, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 580, D-69120 Heidelberg, Germany;
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12
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Liberio MS, Sadowski MC, Davis RA, Rockstroh A, Vasireddy R, Lehman ML, Nelson CC. The ascidian natural product eusynstyelamide B is a novel topoisomerase II poison that induces DNA damage and growth arrest in prostate and breast cancer cells. Oncotarget 2016; 6:43944-63. [PMID: 26733491 PMCID: PMC4791278 DOI: 10.18632/oncotarget.6267] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2015] [Accepted: 10/08/2015] [Indexed: 12/25/2022] Open
Abstract
As part of an anti-cancer natural product drug discovery program, we recently identified eusynstyelamide B (EB), which displayed cytotoxicity against MDA-MB-231 breast cancer cells (IC50 = 5 μM) and induced apoptosis. Here, we investigated the mechanism of action of EB in cancer cell lines of the prostate (LNCaP) and breast (MDA-MB-231). EB inhibited cell growth (IC50 = 5 μM) and induced a G2 cell cycle arrest, as shown by a significant increase in the G2/M cell population in the absence of elevated levels of the mitotic marker phospho-histone H3. In contrast to MDA-MB-231 cells, EB did not induce cell death in LNCaP cells when treated for up to 10 days. Transcript profiling and Ingenuity Pathway Analysis suggested that EB activated DNA damage pathways in LNCaP cells. Consistent with this, CHK2 phosphorylation was increased, p21CIP1/WAF1 was up-regulated and CDC2 expression strongly reduced by EB. Importantly, EB caused DNA double-strand breaks, yet did not directly interact with DNA. Analysis of topoisomerase II-mediated decatenation discovered that EB is a novel topoisomerase II poison.
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Affiliation(s)
- Michelle S Liberio
- Australian Prostate Cancer Research Centre - Queensland, Institute of Health and Biomedical Innovation, Queensland University of Technology, Princess Alexandra Hospital, Translational Research Institute, Brisbane, Queensland, Australia.,Eskitis Institute for Drug Discovery, Griffith University, Nathan, Queensland, Australia
| | - Martin C Sadowski
- Australian Prostate Cancer Research Centre - Queensland, Institute of Health and Biomedical Innovation, Queensland University of Technology, Princess Alexandra Hospital, Translational Research Institute, Brisbane, Queensland, Australia
| | - Rohan A Davis
- Eskitis Institute for Drug Discovery, Griffith University, Nathan, Queensland, Australia
| | - Anja Rockstroh
- Australian Prostate Cancer Research Centre - Queensland, Institute of Health and Biomedical Innovation, Queensland University of Technology, Princess Alexandra Hospital, Translational Research Institute, Brisbane, Queensland, Australia
| | - Raj Vasireddy
- Australian Prostate Cancer Research Centre - Queensland, Institute of Health and Biomedical Innovation, Queensland University of Technology, Princess Alexandra Hospital, Translational Research Institute, Brisbane, Queensland, Australia
| | - Melanie L Lehman
- Vancouver Prostate Centre, University of British Columbia, Vancouver, British Columbia, Canada
| | - Colleen C Nelson
- Australian Prostate Cancer Research Centre - Queensland, Institute of Health and Biomedical Innovation, Queensland University of Technology, Princess Alexandra Hospital, Translational Research Institute, Brisbane, Queensland, Australia
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13
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Wang C, Zhang F, Cao Y, Zhang M, Wang A, Xu M, Su M, Zhang M, Zhuge Y. Etoposide Induces Apoptosis in Activated Human Hepatic Stellate Cells via ER Stress. Sci Rep 2016; 6:34330. [PMID: 27680712 PMCID: PMC5041150 DOI: 10.1038/srep34330] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Accepted: 09/12/2016] [Indexed: 12/11/2022] Open
Abstract
The activation of hepatic stellate cells (HSCs) plays a vital role in the progression of liver fibrosis, and the induction of HSCs apoptosis may attenuate or reverse fibrogenesis. The therapeutic effects of etoposide(VP-16), a widely used anticancer agent, on HSCs apoptosis and liver fibrosis resolution are still unclear. Here, we report that VP-16 reduced the proliferation of LX-2 cells and led to significantly high levels of apoptosis, as indicated by Annexin V staining and the proteolytic cleavage of the executioner caspase-3 and PARP. Additionally, the unfolded protein response regulators CHOP, BIP, caspase-12, p-eIF2α and IRE1α, which are considered endoplasmic reticulum (ER) stress markers, were upregulated by VP-16. The strong inhibitory effect of VP-16 on LX-2 cells was mainly dependent on ER stress, which activated JNK signaling pathway. Remarkably, VP-16 treatment decreased the expression of α-SMA and type I collagen and simultaneously increased the ratio of matrix metalloproteinases (MMPs) to tissue inhibitor of matrix metalloproteinases (TIMPs). In contrast, VP-16 induced significantly more apoptosis in HSCs than in normal hepatocytes. Taken together, our findings demonstrate that VP-16 exerts a proapoptotic effect on LX-2 cells and has an antifibrogenic effect on collagen deposition, suggesting a new strategy for the treatment of liver fibrosis.
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Affiliation(s)
- Chen Wang
- Department of Gastroenterology, Drum Tower Hospital, Medical School of Nanjing University, Nanjing, China
| | - Feng Zhang
- Department of Gastroenterology, Drum Tower Hospital, Medical School of Nanjing University, Nanjing, China
| | - Yu Cao
- Department of Gastroenterology, Drum Tower Hospital, Medical School of Nanjing University, Nanjing, China
| | - Mingming Zhang
- Department of Gastroenterology, Drum Tower Hospital, Medical School of Nanjing University, Nanjing, China
| | - Aixiu Wang
- Department of Gastroenterology, Drum Tower Hospital, Medical School of Nanjing University, Nanjing, China
| | - Mingcui Xu
- Department of Gastroenterology, Affiliated Drum Tower Clinical Medical School of Nanjing Medical University, Nanjing, China
| | - Min Su
- Department of Gastroenterology, Drum Tower Hospital, Medical School of Nanjing University, Nanjing, China
| | - Ming Zhang
- Department of Gastroenterology, Drum Tower Hospital, Medical School of Nanjing University, Nanjing, China
| | - Yuzheng Zhuge
- Department of Gastroenterology, Drum Tower Hospital, Medical School of Nanjing University, Nanjing, China
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14
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Barsanti PA, Pan Y, Lu Y, Jain R, Cox M, Aversa RJ, Dillon MP, Elling R, Hu C, Jin X, Knapp M, Lan J, Ramurthy S, Rudewicz P, Setti L, Subramanian S, Mathur M, Taricani L, Thomas G, Xiao L, Yue Q. Structure-Based Drug Design of Novel, Potent, and Selective Azabenzimidazoles (ABI) as ATR Inhibitors. ACS Med Chem Lett 2015; 6:42-6. [PMID: 25589928 DOI: 10.1021/ml500352s] [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: 08/29/2014] [Accepted: 10/30/2014] [Indexed: 12/15/2022] Open
Abstract
Compound 13 was discovered through morphing of the ATR biochemical HTS hit 1. The ABI series was potent and selective for ATR. Incorporation of a 6-azaindole afforded a marked increase in cellular potency but was associated with poor PK and hERG ion channel inhibition. DMPK experiments established that CYP P450 and AO metabolism in conjunction with Pgp and BCRP efflux were major causative mechanisms for the observed PK. The series also harbored the CYP3A4 TDI liability driven by the presence of both a morpholine and an indole moiety. Incorporation of an adjacent fluorine or nitrogen into the 6-azaindole addressed many of the various medicinal chemistry issues encountered.
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Affiliation(s)
- Paul A Barsanti
- Global
Discovery Chemistry/Oncology, Novartis Institutes for Biomedical Research, 5300 Chiron Way, Emeryville, California 94608, United States
| | - Yue Pan
- Global
Discovery Chemistry/Oncology, Novartis Institutes for Biomedical Research, 5300 Chiron Way, Emeryville, California 94608, United States
| | - Yipin Lu
- Global
Discovery Chemistry/Oncology, Novartis Institutes for Biomedical Research, 5300 Chiron Way, Emeryville, California 94608, United States
| | - Rama Jain
- Global
Discovery Chemistry/Oncology, Novartis Institutes for Biomedical Research, 5300 Chiron Way, Emeryville, California 94608, United States
| | - Matthew Cox
- Global
Discovery Chemistry/Oncology, Novartis Institutes for Biomedical Research, 5300 Chiron Way, Emeryville, California 94608, United States
| | - Robert J. Aversa
- Global
Discovery Chemistry/Oncology, Novartis Institutes for Biomedical Research, 5300 Chiron Way, Emeryville, California 94608, United States
| | - Michael P. Dillon
- Global
Discovery Chemistry/Oncology, Novartis Institutes for Biomedical Research, 5300 Chiron Way, Emeryville, California 94608, United States
| | - Robert Elling
- Global
Discovery Chemistry/Oncology, Novartis Institutes for Biomedical Research, 5300 Chiron Way, Emeryville, California 94608, United States
| | - Cheng Hu
- Global
Discovery Chemistry/Oncology, Novartis Institutes for Biomedical Research, 5300 Chiron Way, Emeryville, California 94608, United States
| | - Xianming Jin
- Global
Discovery Chemistry/Oncology, Novartis Institutes for Biomedical Research, 5300 Chiron Way, Emeryville, California 94608, United States
| | - Mark Knapp
- Global
Discovery Chemistry/Oncology, Novartis Institutes for Biomedical Research, 5300 Chiron Way, Emeryville, California 94608, United States
| | - Jiong Lan
- Global
Discovery Chemistry/Oncology, Novartis Institutes for Biomedical Research, 5300 Chiron Way, Emeryville, California 94608, United States
| | - Savithri Ramurthy
- Global
Discovery Chemistry/Oncology, Novartis Institutes for Biomedical Research, 5300 Chiron Way, Emeryville, California 94608, United States
| | - Patrick Rudewicz
- Global
Discovery Chemistry/Oncology, Novartis Institutes for Biomedical Research, 5300 Chiron Way, Emeryville, California 94608, United States
| | - Lina Setti
- Global
Discovery Chemistry/Oncology, Novartis Institutes for Biomedical Research, 5300 Chiron Way, Emeryville, California 94608, United States
| | - Sharadha Subramanian
- Global
Discovery Chemistry/Oncology, Novartis Institutes for Biomedical Research, 5300 Chiron Way, Emeryville, California 94608, United States
| | - Michelle Mathur
- Global
Discovery Chemistry/Oncology, Novartis Institutes for Biomedical Research, 5300 Chiron Way, Emeryville, California 94608, United States
| | - Lorena Taricani
- Global
Discovery Chemistry/Oncology, Novartis Institutes for Biomedical Research, 5300 Chiron Way, Emeryville, California 94608, United States
| | - George Thomas
- Global
Discovery Chemistry/Oncology, Novartis Institutes for Biomedical Research, 5300 Chiron Way, Emeryville, California 94608, United States
| | - Linda Xiao
- Global
Discovery Chemistry/Oncology, Novartis Institutes for Biomedical Research, 5300 Chiron Way, Emeryville, California 94608, United States
| | - Qin Yue
- Global
Discovery Chemistry/Oncology, Novartis Institutes for Biomedical Research, 5300 Chiron Way, Emeryville, California 94608, United States
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15
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Barsanti PA, Aversa RJ, Jin X, Pan Y, Lu Y, Elling R, Jain R, Knapp M, Lan J, Lin X, Rudewicz P, Sim J, Taricani L, Thomas G, Xiao L, Yue Q. Structure-Based Drug Design of Novel Potent and Selective Tetrahydropyrazolo[1,5-a]pyrazines as ATR Inhibitors. ACS Med Chem Lett 2015; 6:37-41. [PMID: 25589927 DOI: 10.1021/ml500353p] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2014] [Accepted: 11/20/2014] [Indexed: 12/14/2022] Open
Abstract
A saturation strategy focused on improving the selectivity and physicochemical properties of ATR inhibitor HTS hit 1 led to a novel series of highly potent and selective tetrahydropyrazolo[1,5-a]pyrazines. Use of PI3Kα mutants as ATR crystal structure surrogates was instrumental in providing cocrystal structures to guide the medicinal chemistry designs. Detailed DMPK studies involving cyanide and GSH as trapping agents during microsomal incubations, in addition to deuterium-labeled compounds as mechanistic probes uncovered the molecular basis for the observed CYP3A4 TDI in the series.
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Affiliation(s)
- Paul A Barsanti
- Global
Discovery Chemistry
Oncology, Novartis Institutes for Biomedical Research, 5300 Chiron
Way, Emeryville, California 94608, United States
| | - Robert J. Aversa
- Global
Discovery Chemistry
Oncology, Novartis Institutes for Biomedical Research, 5300 Chiron
Way, Emeryville, California 94608, United States
| | - Xianming Jin
- Global
Discovery Chemistry
Oncology, Novartis Institutes for Biomedical Research, 5300 Chiron
Way, Emeryville, California 94608, United States
| | - Yue Pan
- Global
Discovery Chemistry
Oncology, Novartis Institutes for Biomedical Research, 5300 Chiron
Way, Emeryville, California 94608, United States
| | - Yipin Lu
- Global
Discovery Chemistry
Oncology, Novartis Institutes for Biomedical Research, 5300 Chiron
Way, Emeryville, California 94608, United States
| | - Robert Elling
- Global
Discovery Chemistry
Oncology, Novartis Institutes for Biomedical Research, 5300 Chiron
Way, Emeryville, California 94608, United States
| | - Rama Jain
- Global
Discovery Chemistry
Oncology, Novartis Institutes for Biomedical Research, 5300 Chiron
Way, Emeryville, California 94608, United States
| | - Mark Knapp
- Global
Discovery Chemistry
Oncology, Novartis Institutes for Biomedical Research, 5300 Chiron
Way, Emeryville, California 94608, United States
| | - Jiong Lan
- Global
Discovery Chemistry
Oncology, Novartis Institutes for Biomedical Research, 5300 Chiron
Way, Emeryville, California 94608, United States
| | - Xiaodong Lin
- Global
Discovery Chemistry
Oncology, Novartis Institutes for Biomedical Research, 5300 Chiron
Way, Emeryville, California 94608, United States
| | - Patrick Rudewicz
- Global
Discovery Chemistry
Oncology, Novartis Institutes for Biomedical Research, 5300 Chiron
Way, Emeryville, California 94608, United States
| | - Janet Sim
- Global
Discovery Chemistry
Oncology, Novartis Institutes for Biomedical Research, 5300 Chiron
Way, Emeryville, California 94608, United States
| | - Lorena Taricani
- Global
Discovery Chemistry
Oncology, Novartis Institutes for Biomedical Research, 5300 Chiron
Way, Emeryville, California 94608, United States
| | - George Thomas
- Global
Discovery Chemistry
Oncology, Novartis Institutes for Biomedical Research, 5300 Chiron
Way, Emeryville, California 94608, United States
| | - Linda Xiao
- Global
Discovery Chemistry
Oncology, Novartis Institutes for Biomedical Research, 5300 Chiron
Way, Emeryville, California 94608, United States
| | - Qin Yue
- Global
Discovery Chemistry
Oncology, Novartis Institutes for Biomedical Research, 5300 Chiron
Way, Emeryville, California 94608, United States
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16
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Menezes DL, Holt J, Tang Y, Feng J, Barsanti P, Pan Y, Ghoddusi M, Zhang W, Thomas G, Holash J, Lees E, Taricani L. A Synthetic Lethal Screen Reveals Enhanced Sensitivity to ATR Inhibitor Treatment in Mantle Cell Lymphoma with ATM Loss-of-Function. Mol Cancer Res 2014; 13:120-9. [DOI: 10.1158/1541-7786.mcr-14-0240] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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17
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Zhang D, Cui Y, Shen H, Xing L, Cui J, Wang J, Zhang X. Sterigmatocystin-induced DNA damage triggers G2 arrest via an ATM/p53-related pathway in human gastric epithelium GES-1 cells in vitro. PLoS One 2013; 8:e65044. [PMID: 23705030 PMCID: PMC3660384 DOI: 10.1371/journal.pone.0065044] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2012] [Accepted: 04/25/2013] [Indexed: 11/18/2022] Open
Abstract
Sterigmatocystin (ST), which is commonly detected in food and feed commodities, is a mutagenic and carcinogenic mycotoxin that has been recognized as a possible human carcinogen. Our previous study showed that ST can induce G2 phase arrest in GES-1 cells in vitro and that the MAPK and PI3K signaling pathways are involved in the ST-induced G2 arrest. It is now widely accepted that DNA damage plays a critical role in the regulation of cell cycle arrest and apoptosis. In response to DNA damage, a complex signaling network is activated in eukaryotic cells to trigger cell cycle arrest and facilitate DNA repair. To further explore the molecular mechanism through which ST induces G2 arrest, the current study was designed to precisely dissect the role of DNA damage and the DNA damage sensor ataxia telangiectasia-mutated (ATM)/p53-dependent pathway in the ST-induced G2 arrest in GES-1 cells. Using the comet assay, we determined that ST induces DNA damage, as evidenced by the formation of DNA comet tails, in GES-1 cells. We also found that ST induces the activation of ATM and its downstream molecules, Chk2 and p53, in GES-1 cells. The ATM pharmacological inhibitor caffeine was found to effectively inhibit the activation of the ATM-dependent pathways and to rescue the ST-induced G2 arrest in GES-1 cells, which indicating its ATM-dependent characteristic. Moreover, the silencing of the p53 expression with siRNA effectively attenuated the ST-induced G2 arrest in GES-1 cells. We also found that ST induces apoptosis in GES-1 cells. Thus, our results show that the ST-induced DNA damage activates the ATM/53-dependent signaling pathway, which contributes to the induction of G2 arrest in GES-1 cells.
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Affiliation(s)
- Donghui Zhang
- Laboratory of Pathology, Hebei Medical University, Shijiazhuang, China
- Department of Pathology, The Second Hospital, Hebei Medical University, Shijiazhuang, China
| | - Yu Cui
- Laboratory of Pathology, Hebei Medical University, Shijiazhuang, China
| | - Haitao Shen
- Laboratory of Pathology, Hebei Medical University, Shijiazhuang, China
| | - Lingxiao Xing
- Laboratory of Pathology, Hebei Medical University, Shijiazhuang, China
| | - Jinfeng Cui
- Department of Pathology, The Second Hospital, Hebei Medical University, Shijiazhuang, China
| | - Juan Wang
- Laboratory of Pathology, Hebei Medical University, Shijiazhuang, China
| | - Xianghong Zhang
- Laboratory of Pathology, Hebei Medical University, Shijiazhuang, China
- Department of Pathology, The Second Hospital, Hebei Medical University, Shijiazhuang, China
- * E-mail:
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18
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Johnson N, Shapiro GI. Cyclin-dependent kinases (cdks) and the DNA damage response: rationale for cdk inhibitor-chemotherapy combinations as an anticancer strategy for solid tumors. Expert Opin Ther Targets 2010; 14:1199-212. [PMID: 20932174 PMCID: PMC3957489 DOI: 10.1517/14728222.2010.525221] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
IMPORTANCE OF THE FIELD The eukaryotic cell division cycle is a tightly regulated series of events coordinated by the periodic activation of multiple cyclin-dependent kinases (cdks). Small-molecule cdk-inhibitory compounds have demonstrated preclinical synergism with DNA-damaging agents in solid tumor models. An improved understanding of how cdks regulate the DNA damage response now provides an opportunity for optimization of combinations of cdk inhibitors and DNA damaging chemotherapy agents that can be translated to clinical settings. AREAS COVERED IN THIS REVIEW Here, we discuss novel work uncovering multiple roles for cdks in the DNA-damage-response network. First, they activate DNA damage checkpoint and repair pathways. Later their activity is turned off, resulting in cell cycle arrest, allowing time for DNA repair to occur. Recent clinical data on cdk inhibitor-DNA-damaging agent combinations are also discussed. WHAT THE READER WILL GAIN Readers will learn about novel areas of cdk biology, the complexity of DNA damage signaling networks and clinical implications. TAKE HOME MESSAGE New data demonstrate that cdks are 'master' regulators of DNA damage checkpoint and repair pathways. Cdk inhibition may therefore provide a means of potentiating the clinical activity of DNA-damaging chemotherapeutic agents for the treatment of cancer.
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Affiliation(s)
- Neil Johnson
- Dana-Farber Cancer Institute, Department of Medical Oncology, Dana 810A, 44 Binney Street, Boston, MA 02215, USA
- Brigham and Women's Hospital and Harvard Medical School, Department of Medicine, Boston, MA 02215, USA
| | - Geoffrey I Shapiro
- Dana-Farber Cancer Institute, Department of Medical Oncology, Dana 810A, 44 Binney Street, Boston, MA 02215, USA
- Brigham and Women's Hospital and Harvard Medical School, Department of Medicine, Boston, MA 02215, USA
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19
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Cui J, Xing L, Li Z, Wu S, Wang J, Liu J, Wang J, Yan X, Zhang X. Ochratoxin A induces G2 phase arrest in human gastric epithelium GES-1 cells in vitro. Toxicol Lett 2010; 193:152-8. [PMID: 20060447 DOI: 10.1016/j.toxlet.2009.12.019] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2009] [Revised: 12/23/2009] [Accepted: 12/30/2009] [Indexed: 12/28/2022]
Affiliation(s)
- Jinfeng Cui
- Department of Pathology, The Second Hospital, Hebei Medical University, Shijiazhuang, China
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20
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Sugimoto K, Sasaki M, Isobe Y, Tsutsui M, Suto H, Ando J, Tamayose K, Ando M, Oshimi K. Hsp90-inhibitor geldanamycin abrogates G2 arrest in p53-negative leukemia cell lines through the depletion of Chk1. Oncogene 2007; 27:3091-101. [PMID: 18071310 DOI: 10.1038/sj.onc.1210978] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Checkpoint protein Chk1 has been identified as an Hsp90 client. Treatment with 100 nM geldanamycin (GM) for 24 h markedly reduced the Chk1 amount in Jurkat and ML-1 leukemia cell lines. Because Chk1 plays a central role in G2 checkpoint, we added GM to G2-arrested Jurkat and HL-60 cells pretreated with 50 nM doxorubicin for 24 h. GM slowly released both cell lines from doxorubicin-induced G2 arrest into G1 phase. GM also abrogated ICRF-193-induced decatenation G2 checkpoint in Jurkat and HL-60 cells. Western blot analysis showed that addition of GM attenuates doxorubicin- and ICRF-193-induced Chk1 phosphorylation at Ser345. GM, however, failed to abrogate G2 arrest in p53-positive ML-1 cells maybe due to the p21 induction. GM released HeLa cells from doxorubicin-induced G2 arrest but trapped them at M phase. Flow cytometric analysis showed that addition of GM converted doxorubicin-induced necrosis into apoptosis in Jurkat cells. Colony assay indicated that although GM has a weak cytotoxic effect as a single agent, it dramatically intensifies the cytotoxicity of doxorubicin and ICRF-193 in Jurkat and HL-60 cells. These results suggest that abrogation of G2 checkpoint by GM may play a central role in sensitizing p53-negative tumor cells to DNA-damaging and decatenation-inhibiting agents.
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Affiliation(s)
- K Sugimoto
- Division of Hematology, Department of Internal Medicine, Juntendo University School of Medicine, Tokyo, Japan.
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21
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Huang JY, Morley G, Li D, Whitaker M. Cdk1 phosphorylation sites on Cdc27 are required for correct chromosomal localisation and APC/C function in syncytial Drosophila embryos. J Cell Sci 2007; 120:1990-7. [PMID: 17519285 PMCID: PMC2082081 DOI: 10.1242/jcs.006833] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Anaphase-promoting complex or cyclosome (APC/C) controls the metaphase-to-anaphase transition and mitosis exit by triggering the degradation of key cell cycle regulators such as securin and B-type cyclins. However, little is known about the functions of individual APC/C subunits and how they might regulate APC/C activity in space and time. Here, we report that two potential Cdk1 kinase phosphorylation sites are required for the chromosomal localisation of GFP::Cdc27 during mitosis. Either or both of the highly conserved proline residues in the Cdk1 phosphorylation consensus sequence motifs were mutated to alanine (Cdc27 P304A or P456A). The singly mutated fusion proteins, GFP::Cdc27P304A and GFP::Cdc27P456A, can still localise to mitotic chromosomes in a manner identical to wild-type GFP::Cdc27 and are functional in that they can rescue the phenotype of the cdc27L7123 mutant in vivo. However, when both of the Cdk1 phosphorylation sequence motifs were mutated, the resulting GFP::Cdc27P304A,P456A construct was not localised to the chromosomes during mitosis and was no longer functional, as it failed to rescue mutant phenotypes of the cdc27L7123 gene. High levels of cyclin B and cyclin A were detected in mutant third instar larvae brain samples compared with its wild-type control. These results show for the first time that the two potential Cdk1 phosphorylation sites on Drosophila Cdc27 are required for its chromosomal localisation during mitosis and imply that these localisations specific to Cdc27 are crucial for APC/C functions.
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Affiliation(s)
- Jun-Yong Huang
- Institute for Cell and Molecular Biosciences, Faculty of Medical Sciences, University of Newcastle upon Tyne, Catherine Cookson Building, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK.
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Tazuke Y, Wildhaber BE, Yang H, Washburn J, Teitelbaum DH. Total parenteral nutrition leads to alteration of hepatocyte cell cycle gene expression and proliferation in the mouse. Dig Dis Sci 2007; 52:920-30. [PMID: 17342396 DOI: 10.1007/s10620-006-9364-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/10/2005] [Accepted: 01/30/2006] [Indexed: 12/09/2022]
Abstract
Total parenteral nutrition (TPN) is correlated with progressive liver injury. Such injury may be associated with either an increase or decrease in hepatocyte growth. The goal of these experiments was to determine TPN-related alterations in intrahepatic genes, as they relate with the cell cycle, using microarray techniques. After 7 days of infusion of saline or TPN-solution, hepatocyte gene expression was examined with a 5000-cDNA microarray chip. TPN was associated with an up-regulation of the cyclin kinase Cdc25B mRNA, which controls the cell cycle at the G2/M phase. Based on this, our studies were directed at alterations in genes related to mitosis in this phase of the cell cycle. mRNA expression of mitotic phase inducers and inhibitors were examined. Cdc25B1 mRNA expression increased with TPN. TPN also led to additional significant alterations in the expression of other factors which mediate proliferation in this phase of mitosis. Histologically, TPN resulted in a significant decline in hepatocyte proliferation. Coincident with the alteration in cyclin expression was a significant decrease in hepatocytes in the G2/M phase with TPN administration. This study demonstrates significant alterations in cell cycle gene expression with TPN. The findings correlate with a loss of hepatocyte proliferation and may give insight into the potential mechanism of TPN-induced hepatocyte injury.
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Affiliation(s)
- Yuko Tazuke
- Section of Pediatric Surgery, C.S. Mott Children's Hospital, Department of Surgery, University of Michigan Medical School, F3970 Mott Children's Hospital, Box 0245, Ann Arbor, MI 48109, USA
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23
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Abstract
Spermatocytes normally sustain many meiotically induced double-strand DNA breaks (DSBs) early in meiotic prophase; in autosomal chromatin, these are repaired by initiation of meiotic homologous-recombination processes. Little is known about how spermatocytes respond to environmentally induced DNA damage after recombination-related DSBs have been repaired. The experiments described here tested the hypothesis that, even though actively completing meiotic recombination, pachytene spermatocytes cultured in the absence of testicular somatic cells initiate appropriate chromatin remodeling and cell-cycle responses to environmentally induced DNA damage. Two DNA-damaging agents were employed for in vitro treatment of pachytene spermatocytes: gamma-irradiation and etoposide, a topoisomerase II (TOP2) inhibitor that results in persistent unligated DSBs. Chromatin modifications associated with DSBs were monitored after exposure by labeling surface-spread chromatin with antibodies against RAD51 (which recognizes DSBs) and the phosphorylated variant of histone H2AFX (herein designated by its commonly used symbol, H2AX), gammaH2AX (which modifies chromatin associated with DSBs). Both gammaH2AX and RAD51 were rapidly recruited to irradiation- or etoposide-damaged chromatin. These chromatin modifications imply that spermatocytes recruit active DNA damage responses, even after recombination is substantially completed. Furthermore, irradiation-induced DNA damage inhibited okadaic acid-induced progression of spermatocytes from meiotic prophase to metaphase I (MI), implying efficacy of DNA damage checkpoint mechanisms. Apoptotic responses of spermatocytes with DNA damage differed, with an increase in frequency of early apoptotic spermatocytes after etoposide treatment, but not following irradiation. Taken together, these results demonstrate modification of pachytene spermatocyte chromatin and inhibition of meiotic progress after DNA damage by mechanisms that may ensure gametic genetic integrity.
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Affiliation(s)
- Shannon Matulis
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, USA
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24
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Guan H, Chen H, Peng W, Ma Y, Cao R, Liu X, Xu A. Design of β-carboline derivatives as DNA-targeting antitumor agents. Eur J Med Chem 2006; 41:1167-79. [PMID: 16790297 DOI: 10.1016/j.ejmech.2006.05.004] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 04/29/2006] [Accepted: 05/05/2006] [Indexed: 11/21/2022]
Abstract
This research studied the structure-activity relationship of beta-carboline derivatives as antitumor agents, in which 41 synthesized compounds and their cytotoxicity to tumor and normal cell lines were assayed. It was proved that substituent in position-9 of the beta-carboline ring could reinforce the DNA intercalating ability and consequently cytotoxicity to tumor cell lines, and the amidation of amino group at the end of the DNA targeting side chain in position-3 could cripple the DNA intercalating activity of these compounds, which resultingly initiated the cytotoxic selectivity to tumor cell lines rather than to normal ones. Furthermore, the S and G2-M arrest induced by these compounds confirmed that they could target DNA and lead to DNA destructions in Hela cells. In short, this study may provide a framework to design a novel antitumor drug that could surpass Adriamycin.
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Affiliation(s)
- Huaji Guan
- State Key Laboratory of Biocontrol, Guangdong Key Laboratory of Therapeutic Functional Genes, Department of Biochemistry, College of Life Sciences, Sun Yat-sen (Zhongshan) University, 135, Xin Gang Xi Road, Guangzhou 510275, China
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25
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Ashra H, Rao KVK. Elevated phosphorylation of Chk1 and decreased phosphorylation of Chk2 are associated with abrogation of G2/M checkpoint control during transformation of Syrian hamster embryo (SHE) cells by Malachite green. Cancer Lett 2006; 237:188-98. [PMID: 16085357 DOI: 10.1016/j.canlet.2005.05.044] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2005] [Revised: 05/26/2005] [Accepted: 05/30/2005] [Indexed: 10/25/2022]
Abstract
Malachite green (MG), consisting of green crystals with a metallic lustre, is highly soluble in water, cytotoxic to various mammalian cells and also acts as a liver tumor promoter. In view of its industrial importance and possible exposure to human beings, MG poses a potential environmental health hazard. We have earlier reported the malignant transformation of Syrian hamster embryo (SHE) cells in primary culture by MG. In this study, we have studied the ability of MG to cause DNA damage, cell cycle arrest in mimosine synchronised and the possible roles of Chk1, Chk2, Cdc2, Cdc25C, 14-3-3 and Cyclin B1 in control and MG transformed SHE cells in order to understand the differential mechanisms associated with G2/M checkpoint control. Exposure of MG to control and transformed cells causes DNA damage. Flow cytometric analysis of mimosine synchronised cells when exposed to MG showed an increase of G2/M phase in control cells whereas no such accumulation of cells at the G2/M phase was observed in response to MG in transformed cells. Western blots of phosphoactive forms of Chk1 and Chk2 cells showed opposing levels. Control cells treated with MG showed a decrease in Chk1 and increase in Chk2, whereas the transformed cells treated with MG showed an increase in Chk1 and decrease in Chk2. Also a decrease in Cdc25C, 14-3-3 and Cyclin B1 was observed in MG treated transformed cells, whereas MG treated control cells showed elevated levels. Stabilization of the proteins seems to be the possible mechanism. The present study indicates elevated phosphorylation of Chk1 and decreased phosphorylation of Chk2 and decreased levels of Cyclin B1 are the critical changes associated with abrogation of G2/M checkpoint control during transformation of SHE cells by MG.
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Affiliation(s)
- Hima Ashra
- Chemical Carcinogenesis Group, Advanced Centre for Treatment, Research and Education in Cancer (ACTREC), Tata Memorial Centre, Kharghar, Navi Mumbai 410208, India
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26
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Guan H, Liu X, Peng W, Cao R, Ma Y, Chen H, Xu A. β-carboline derivatives: Novel photosensitizers that intercalate into DNA to cause direct DNA damage in photodynamic therapy. Biochem Biophys Res Commun 2006; 342:894-901. [PMID: 16598841 DOI: 10.1016/j.bbrc.2006.02.035] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Novel 1,3,9-trisubstituted beta-carboline derivatives were found to exhibit DNA photocleavage properties under visible light irradiation in a cell-free system, which could be reduced by antioxidant vitamin E. Their photo-cytotoxicity to human tumor cell line HeLa was confirmed, in which apoptosis only contributed a small part to the cell death, and necrosis was the dominating outcome of HeLa cells in photodynamic therapy (PDT) using beta-carboline derivatives. Different from other clinical PDT drugs, beta-carboline derivatives were demonstrated to be able to distribute in the nucleus and intercalate into DNA, and consequently cause direct DNA damage by photochemical reaction products in PDT, which was proved by the distinct DNA tails in the comet assay and the considerable amount of DNA damaged cells quantified by flow cytometry. This mechanism could be the explanation for the delay of cell proliferation at DNA synthesis and mitosis.
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Affiliation(s)
- Huaji Guan
- State Key Laboratory of Biocontrol, Guangdong Key Laboratory of Therapeutic Functional Genes, Department of Biochemistry, College of Life Sciences, Sun Yat-sen (Zhongshan) University, 135 Xin Gang Xi Road, Guangzhou 510275, People's Republic of China
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27
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A graphical chain model for inferring regulatory system networks from gene expression profiles. ACTA ACUST UNITED AC 2006. [DOI: 10.1016/j.stamet.2005.08.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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28
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Chiu CC, Lin CHMY, Fang K. Etoposide (VP-16) sensitizes p53-deficient human non-small cell lung cancer cells to caspase-7-mediated apoptosis. Apoptosis 2005; 10:643-50. [PMID: 15909125 DOI: 10.1007/s10495-005-1898-8] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Human non-small-cell-lung-cancer (NSCLC) cells of (p)53-null genotype were exposed to low-dosage topoisomearse II inhibitor etoposide (VP-16). The cellular proliferation rate could be effectively inhibited by VP-16 in dose-dependent manner. The effective drug concentration for growth inhibition could be as low as 0.5 microM and the apoptotic phenotype became evident 48 h later. In H1299 cells, VP-16-induced cytotoxic effect was demonstrated associated with apoptosis that disappeared when restored with wild-type p53. Cell cycle analysis revealed that, upon VP-16 induction, cell death began with growth arrest by accumulating cells at the G(2)-M phase. The cells at sub-G(1) phase increased at the expense of those at G(2)-M transition state. To assess the regulation of cell cycle modulators, western blot analysis of H1299 cell lysates showed the release of apoptosis initiator, cytochrome c and apaf-1 hours following drug induction. The cleavage of downstream effectors, procaspase-9 and procaspase-7, but not procaspase-3, was accompanied with proteolysis of poly-(ADP-ribose) polymerase (PARP). VP-16-activated procaspase-7 cleavage was abrogated in cells with ectopically expressed p53. On the other hand, the inhibited procaspase-7 fragmentation by caspase-specific inhibitor reversed apoptotic phenotype caused by drug induction. Thus, VP-16-induced apoptotic cell death was contributed by caspase-7 activation in(p)53-deficient human NSCLC cells.
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Affiliation(s)
- C-C Chiu
- Department of Biological Science, National Taiwan Normal University, Taipei, Taiwan
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29
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Reitmair A, Shurland DL, Tsang KY, Chandraratna RAS, Brown G. Retinoid-related molecule AGN193198 potently induces G2M arrest and apoptosis in bladder cancer cells. Int J Cancer 2005; 115:917-23. [PMID: 15729717 DOI: 10.1002/ijc.20961] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The novel synthetic retinoid-related molecule 4-[3-(1-heptyl-4,4-dimethyl-2-oxo-1,2,3,4-tetrahydroquinolin-6-yl)-3-oxo-propenyl]benzoic acid (AGN193198) neither binds effectively to retinoic acid receptors (RARs) and retinoid X receptors (RXRs) nor transactivates in RAR- and RXR-mediated reporter assays. Even so, AGN193198 is potent in inducing apoptosis in human prostate and breast carcinoma cells (Keedwell et al., Cancer Res 2004;64:3302-12). Here, we extend these findings to show that AGN193198 potently and rapidly induces apoptosis in bladder carcinoma cell lines. One micromolar of AGN193198 completely abolished the growth of the transitional cell carcinoma lines UM-UC-3 and J82, and the squamous cell carcinoma line SCaBER; the transitional cell papilloma line RT-4 was slightly less sensitive to the growth inhibitory effect of AGN193198. Treated cells accumulated in the G2M phase of the cell cycle. This was accompanied by apoptosis, as revealed by staining cells for exposure of phosphatidylserine at their surface (binding of Annexin V) and FACS analysis of propidium iodide labeled cells. As reported for prostate cancer cells, AGN193198 provoked rapid activation of caspases-3 (by 6 hr), -8 (by 16 hr) and -9 (by 6 hr) in bladder cancer cells. These findings suggest that AGN193198 and related compounds, whose mechanism of action does not appear to involve RARs and RXRs, may be useful in the treatment of bladder cancer.
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Affiliation(s)
- Armin Reitmair
- Department of Biological Sciences, Allergan, Inc., Irvine, CA, USA
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30
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Gonzalez S, Prives C, Cordon-Cardo C. p73alpha regulation by Chk1 in response to DNA damage. Mol Cell Biol 2003; 23:8161-71. [PMID: 14585975 PMCID: PMC262369 DOI: 10.1128/mcb.23.22.8161-8171.2003] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The checkpoint kinase 1 (Chk1) is an essential component of the DNA damage checkpoint. Previous studies have demonstrated an indispensable role for the p53-related transcription factor p73alpha in DNA damage-induced apoptosis. Here, we provide evidence that p73alpha is a target of Chk1. We found that endogenous p73alpha is serine phosphorylated by endogenous Chk1 upon DNA damage, which is a mechanism required for the apoptotic-inducing function of p73alpha. Consistent with this, we discovered that endogenous p73alpha interacts with Chk1 and is phosphorylated by Chk1 at serine 47 in vitro and in vivo. In contrast, Chk2 does not phosphorylate p73alpha in vitro. Moreover, mutation of serine 47 abolishes both Chk1-dependent phosphorylation of p73alpha upon DNA damage in vivo and the ability of Chk1 to upregulate the transactivation capacity of p73alpha. Our data indicate a novel biochemical pathway through which the p73alpha proapoptotic function requires DNA damage-triggered p73alpha phosphorylation by Chk1.
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Affiliation(s)
- Susana Gonzalez
- Division of Molecular Pathology, Memorial Sloan-Kettering Cancer Center, New York, NY 10021, USA
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31
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Yuan L, Yu WM, Qu CK. DNA damage-induced G2/M checkpoint in SV40 large T antigen-immortalized embryonic fibroblast cells requires SHP-2 tyrosine phosphatase. J Biol Chem 2003; 278:42812-20. [PMID: 12937170 DOI: 10.1074/jbc.m305075200] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
DNA damage induced by radiation or DNA-damaging agents leads to apoptosis and cell cycle arrest. However, DNA damage-triggered signal transduction involved in these cellular responses is not well understood. We previously demonstrated an important role for SHP-2, a ubiquitously expressed SH2 domain-containing tyrosine phosphatase, in the DNA damage-induced apoptotic response. Here we report a potential role for SHP-2 in a DNA damage-activated cell cycle checkpoint. Cell cycle analysis and the mitotic index assay showed that following DNA damage induced by cisplatin or gamma-irradiation, the G2 (but not S) arrest response was diminished in SV40 large T antigen-immortalized embryonic fibroblast cells lacking functional SHP-2. Notably, reintroduction of wild-type SHP-2 into the mutant cells fully restored the DNA damage-induced G2 arrest response, suggesting a direct role of SHP-2 in the G2/M checkpoint. Further biochemical analysis revealed that SHP-2 constitutively associated with 14-3-3beta, and that Cdc25C cytoplasmic translocation induced by DNA damage was essentially blocked in SHP-2 mutant cells. Additionally, we showed that following DNA damage, activation of p38 kinase was significantly elevated, while Erk kinase activation was decreased in mutant cells, and treatment of SHP-2 mutant cells with SB203580, a selective inhibitor for p38 kinase, partially restored the DNA damage-induced G2 arrest response. These results together provide the first evidence that SHP-2 tyrosine phosphatase enhances the DNA damage G2/M checkpoint in SV40 large T antigen immortalized murine embryonic fibroblast cells.
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Affiliation(s)
- Liangping Yuan
- Department of Hematopoiesis, Jerome H. Holland Laboratory for the Biomedical Sciences, American Red Cross, Rockville, Maryland 20855, USA
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32
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Eymin B, Leduc C, Coll JL, Brambilla E, Gazzeri S. p14ARF induces G2 arrest and apoptosis independently of p53 leading to regression of tumours established in nude mice. Oncogene 2003; 22:1822-35. [PMID: 12660818 DOI: 10.1038/sj.onc.1206303] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Until recently, the ability of ARF (human p14(ARF), murine p19(ARF)) tumour-suppressor protein, encoded by the INK4A/ARF locus, to inhibit cell growth in response to various stimuli was related to its ability to stabilize p53 through the so-called ARF/MDM2/p53 pathway. However, recent data have demonstrated that ARF is not implicated in this unique p53-dependent pathway. By use of transient and stable expression, we show here that human p14(ARF) inhibits the growth of human tumoral cells lacking functional p53 by inducing a transient G(2) arrest and subsequently apoptosis. This p14(ARF)-induced G(2) arrest was correlated with inhibition of CDC2 activity, inactivation of CDC25C phosphatase and induction of the CDK inhibitor p21(WAFI). Apoptosis was demonstrated using Hoechst 33352 staining, proteolytic activation of caspase-3 and PARP cleavage. Similar results were obtained in experiments with cells synchronized by hydroxyurea block. Importantly, we were able to reproduce these effects 'in vivo' by showing that p14(ARF) inhibits the growth of p53 nullizygous human tumours in nude mice and induces the regression of p53 -/- established tumours. In these experiments, tumoral regression was associated with inhibition of cell proliferation as well as induction of apoptosis confirming the data obtained in cell lines.
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Affiliation(s)
- Béatrice Eymin
- Groupe de Recherche sur le Cancer du Poumon, EA 2021, Equipe INSERM 9924, Institut Albert Bonniot, La Tronche, France
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Abstract
A Cre/lox-conditional mouse line was generated to evaluate the role of ATR in checkpoint responses to ionizing radiation (IR) and stalled DNA replication. We demonstrate that after IR treatment, ATR and ATM each contribute to early delay in M-phase entry but that ATR regulates a majority of the late phase (2-9 h post-IR). Double deletion of ATR and ATM eliminates nearly all IR-induced delay, indicating that ATR and ATM cooperate in the IR-induced G2/M-phase checkpoint. In contrast to the IR-induced checkpoint, checkpoint delay in response to stalled DNA replication is intact in ATR knockout cells and ATR/ATM and ATR/p53 double-knockout cells. The DNA replication checkpoint remains intact in ATR knockout cells even though the checkpoint-stimulated inhibitory phosphorylation of Cdc2 on T14/Y15 and activating phosphorylation of the Chk1 kinase no longer occur. Thus, incomplete DNA replication in mammalian cells can prevent M-phase entry independently of ATR and inhibitory phosphorylation of Cdc2. When DNA replication inhibitors are removed, ATR knockout cells proceed to mitosis but do so with chromosome breaks, indicating that ATR provides a key genome maintenance function in S phase.
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Affiliation(s)
- Eric J Brown
- California Institute of Technology, Pasadena, California 91125, USA.
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Mamane Y, Grandvaux N, Hernandez E, Sharma S, Innocente SA, Lee JM, Azimi N, Lin R, Hiscott J. Repression of IRF-4 target genes in human T cell leukemia virus-1 infection. Oncogene 2002; 21:6751-65. [PMID: 12360402 DOI: 10.1038/sj.onc.1205843] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2002] [Revised: 06/26/2002] [Accepted: 07/05/2002] [Indexed: 11/10/2022]
Abstract
The human T cell leukemia/lymphotropic virus-1 (HTLV-I) is the etiologic agent of adult T cell leukemia (ATL), an aggressive and fatal leukemia of CD4+ T lymphocytes. Interferon regulatory factor-4 (IRF-4) was shown previously to be constitutively expressed in T cells infected with HTLV-1. In this study, we investigated the role of IRF-4 gene regulation in the context of HTLV-1 infection using gene array technology and IRF-4 expressing T cells. Many potential IRF-4 regulated genes were identified, the vast majority of which were repressed by IRF-4 expression. Cyclin B1, a G2-M checkpoint protein identified as an IRF-4 repressed gene in the array, was further characterized in the context of HTLV-1 infection. All HTLV-1 infected cell lines and ATL patient lymphocytes demonstrated a dramatic decrease in cyclin B1 levels; subsequent analysis of the cyclin B1 promoter identified two sites important in IRF-4 binding and repression of cyclin B1 expression. Furthermore, IRF-4-mediated repression of cyclin B1 led to a significant decrease in CDC2 kinase activity in HTLV-1 infected T cells. IRF-4 expression in HTLV-1 infected T cells also downregulated other genes implicated in the mitotic checkpoint as well as genes involved in actin cytoskeletal rearrangement, DNA repair, apoptosis, metastasis and immune recognition. Several of the identified genes are dysregulated in ATL and may provide important mechanistic information concerning pathways critical to the emergence of ATL.
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Affiliation(s)
- Yaël Mamane
- Terry Fox Molecular Oncology Group, Lady Davis Institute for Medical Research, and Department of Microbiology and Immunology, McGill University, Montreal, Canada H3T 1E2
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35
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Okamoto K, Nakajo N, Sagata N. The existence of two distinct Wee1 isoforms in Xenopus: implications for the developmental regulation of the cell cycle. EMBO J 2002; 21:2472-84. [PMID: 12006499 PMCID: PMC126008 DOI: 10.1093/emboj/21.10.2472] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
In eukaryotic cells, the Wee1 protein kinase phosphorylates and inhibits Cdc2, thereby creating an interphase of the cell cycle. In Xenopus, the conventional Wee1 homolog (termed Xe-Wee1A, or Wee1A for short) is maternally expressed and functions in pregastrula embryos with rapid cell cycles. Here, we have isolated a second, zygotic isoform of Xenopus Wee1, termed Xe-Wee1B (or Wee1B for short), that is expressed in postgastrula embryos and various adult tissues. When ectopically expressed in immature oocytes, Wee1B inhibits Cdc2 activity and oocyte maturation (or entry into M phase) much more strongly than Wee1A, due to its short C-terminal regulatory domain. Moreover, ectopic Wee1B, unlike Wee1A, is very labile during meiosis II and cannot accumulate in mature oocytes due to the presence of PEST-like sequences in its N-terminal regulatory domain. Finally, when expressed in fertilized eggs, ectopic Wee1B but not Wee1A does affect cell division and impair cell viability in early embryos, due primarily to its very strong kinase activity. These results suggest strongly that the differential expression of Wee1A and Wee1B is crucial for the developmental regulation of the cell cycle in Xenopus.
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Affiliation(s)
| | | | - Noriyuki Sagata
- Department of Biology, Graduate School of Sciences, Kyushu University, Hakozaki 6-10-1, Fukuoka 812-8581, Japan
Corresponding author e-mail:
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36
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Lincoln AJ, Wickramasinghe D, Stein P, Schultz RM, Palko ME, De Miguel MP, Tessarollo L, Donovan PJ. Cdc25b phosphatase is required for resumption of meiosis during oocyte maturation. Nat Genet 2002; 30:446-9. [PMID: 11912493 DOI: 10.1038/ng856] [Citation(s) in RCA: 221] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
In a wide variety of animal species, oocyte maturation is arrested temporarily at prophase of meiosis I (ref. 1). Resumption of meiosis requires activation of cyclin-dependent kinase-1 (CDK1, p34cdc2), one component of maturation-promoting factor (MPF). The dual specificity phosphatases Cdc25a, Cdc25b and Cdc25c are activators of cyclin-dependent kinases; consequently, they are postulated to regulate cell-cycle progression in meiosis and mitosis as well as the DNA-damage response. We generated Cdc25b-deficient (Cdc25b-/-) mice and found that they are viable. As compared with wildtype cells, fibroblasts from Cdc25b-/- mice grew vigorously in culture and arrested normally in response to DNA damage. Female Cdc25b-/- mice were sterile, and Cdc25b-/- oocytes remained arrested at prophase with low MPF activity. Microinjection of wildtype Cdc25b mRNA into Cdc25b-/- oocytes caused activation of MPF and resumption of meiosis. Thus, Cdc25b-/- female mice are sterile because of permanent meiotic arrest resulting from the inability to activate MPF. Cdc25b is therefore essential for meiotic resumption in female mice. Mice lacking Cdc25b provide the first genetic model for studying the mechanisms regulating prophase arrest in vertebrates.
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Cummings M, Siitonen T, Higginbottom K, Newland AC, Allen PD. p53-mediated downregulation of Chk1 abrogates the DNA damage-induced G2M checkpoint in K562 cells, resulting in increased apoptosis. Br J Haematol 2002; 116:421-8. [PMID: 11841447 DOI: 10.1046/j.1365-2141.2002.03262.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BCR-ABL confers apoptotic resistance to a range of genotoxic agents, and this protection is mediated in part by prolonging the G2 checkpoint. The p53 tumour suppressor protein regulates the transcription of regulatory genes involved in cell cycle arrest and apoptosis. To investigate the effect of p53 on the BCR-ABL-mediated G2M checkpoint response, we transiently transfected the BCR-ABL-positive, p53-negative cell line K562 with wild-type human p53. The p53-transfected cells showed a decreased ability to arrest in G2 and an increase in apoptosis in response to etoposide treatment, relative to the control mock-transfected cells. p53-transfected and control cells were treated with etoposide and trapped at mitosis with nocodazole. The mitotic index of p53-transfected cells was higher than that of the control cells, which suggests that p53 abrogates the G2 checkpoint response to etoposide treatment in K562 cells. We found that the expression of the cell cycle checkpoint protein Chk1 was reduced in the etoposide-treated p53-transfected cells by 24 h, and this correlated with a reduction in the extent of etoposide-induced phosphorylation of CDK1 at tyrosine 15 (Y15). We conclude, therefore, that p53 overrides the strong G2 checkpoint response to etoposide in K562 cells, by directly or indirectly downregulating Chk1 expression, which, in turn, contributes to the proapoptotic effect of p53.
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Affiliation(s)
- Michele Cummings
- Department of Haematology, St. Bartholomew's and The Royal London School of Medicine and Dentistry, London, UK.
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38
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Wolkow TD, Enoch T. Fission yeast Rad26 is a regulatory subunit of the Rad3 checkpoint kinase. Mol Biol Cell 2002; 13:480-92. [PMID: 11854406 PMCID: PMC65643 DOI: 10.1091/mbc.01-03-0104] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2001] [Revised: 10/24/2001] [Accepted: 11/01/2001] [Indexed: 11/11/2022] Open
Abstract
Fission yeast Rad3 is a member of a family of phosphoinositide 3-kinase -related kinases required for the maintenance of genomic stability in all eukaryotic cells. In fission yeast, Rad3 regulates the cell cycle arrest and recovery activities associated with the G2/M checkpoint. We have developed an assay that directly measures Rad3 kinase activity in cells expressing physiological levels of the protein. Using the assay, we demonstrate directly that Rad3 kinase activity is stimulated by checkpoint signals. Of the five other G2/M checkpoint proteins (Hus1, Rad1, Rad9, Rad17, and Rad26), only Rad26 was required for Rad3 kinase activity. Because Rad26 has previously been shown to interact constitutively with Rad3, our results demonstrate that Rad26 is a regulatory subunit, and Rad3 is the catalytic subunit, of the Rad3/Rad26 kinase complex. Analysis of Rad26/Rad3 kinase activation in rad26.T12, a mutant that is proficient for cell cycle arrest, but defective in recovery, suggests that these two responses to checkpoint signals require quantitatively different levels of kinase activity from the Rad3/Rad26 complex.
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Affiliation(s)
- Tom D Wolkow
- Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA.
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39
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Wang H, Liu D, Wang Y, Qin J, Elledge SJ. Pds1 phosphorylation in response to DNA damage is essential for its DNA damage checkpoint function. Genes Dev 2001; 15:1361-72. [PMID: 11390356 PMCID: PMC312708 DOI: 10.1101/gad.893201] [Citation(s) in RCA: 112] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
In Saccharomyces cerevisiae, Pds1 is an anaphase inhibitor and plays an essential role in DNA damage and spindle checkpoint pathways. Pds1 is phosphorylated in response to DNA damage but not spindle disruption, indicating distinct mechanisms delaying anaphase entry. Phosphorylation of Pds1 is Mec1 and Chk1 dependent in vivo. Here, we show that Pds1 is phosphorylated at multiple sites in vivo in response to DNA damage by Chk1. Mutation of the Chk1 phosphorylation sites on Pds1 abolished most of its DNA damage-inducible phosphorylation and its checkpoint function, whereas its anaphase inhibitor functions and spindle checkpoint functions remain intact. Loss of Pds1 phosphorylation correlates with APC-dependent Pds1 destruction in response to DNA damage. We also show that APC(Cdc20) is active in preanaphase arrested cells after DNA damage. This suggests that Pds1 is stabilized by phosphorylation in response to DNA damage, but APC(Cdc20) activity is not altered. Our results indicate that phosphorylation of Pds1 by Chk1 is the key function of Chk1 required to prevent anaphase entry.
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Affiliation(s)
- H Wang
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas 77030, USA
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40
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Damia G, Sanchez Y, Erba E, Broggini M. DNA Damage Induces p53-dependent Down-regulation of hCHK1. J Biol Chem 2001; 276:10641-5. [PMID: 11152453 DOI: 10.1074/jbc.m007178200] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The levels of the human checkpoint gene hCHK1 were measured in human cancer cells growing in vitro after treatment with the DNA damaging agent cis-dichlorodiammine platinum(II) (DDP). Treatment of human cancer cell lines with DDP induced a decrease in the hCHK1 protein levels starting 6 h after treatment, with a further decline at 24 and 48 h. A similar decrease in the levels of hCHK1 was found at the mRNA level by using Northern blot analysis. By using isogenic cell systems in which p53 was disrupted either by transfection with HPV-E6 or by targeted homologous recombination, we found that the DNA damage-induced down-regulation of hCHK1 was only observable in wild type p53-expressing cells, with only a minor decline in the hCHK1 levels observable 48 h after treatment in cells with disrupted p53. Similarly, treatment of mutant p53-expressing human cancer cell lines with DDP did not result in changes in the levels of hCHK1. The p53-dependent down-regulation of hCHK1 is likely to be at transcriptional levels, as suggested by the lack of down-regulation of the hCHK1 when transfected under the control of a heterologous viral promoter. In addition, p53 is able to down-regulate the luciferase activity under the control of the 5' flanking region of the hCHK1 gene. The data suggest a strict link between p53 and hCHK1 governing the activation and repression of the G(2) checkpoint in which both proteins participate.
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Affiliation(s)
- G Damia
- Molecular Pharmacology Unit, Department of Oncology, Istituto di Ricerche Farmacologiche "Mario Negri," Via Eritrea 62, 20157 Milan, Italy.
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41
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Abstract
The mammalian cell cycle is exquisitely controlled by a 'machinery' composed of cyclin-dependent kinases and their binding partners, the cyclins. These kinases regulate transitions into DNA synthesis and mitosis, and their inactivity contributes to cellular quiescence, differentiation and senescence. Cell cycle transitions are, in turn, controlled by checkpoints that monitor ribonucleotide pools, oxygen tension, the extracellular environment, growth signalling programmes, the status of DNA replication, and the mitotic spindle apparatus. Genes positively controlling cell cycle checkpoints can be targets for oncogenic activation in cancer, whereas negative regulators, such as tumour suppressor genes, are targeted for inactivation. Understanding the molecular details of cell cycle regulation and checkpoint abnormalities in cancer offers insight into potential therapeutic strategies.
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Affiliation(s)
- E R McDonald
- Department of Medicine, Genetics and Pharmacology, University of Pennsylvania School of Medicine, Philadelphia 19104, USA
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42
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Oe T, Nakajo N, Katsuragi Y, Okazaki K, Sagata N. Cytoplasmic occurrence of the Chk1/Cdc25 pathway and regulation of Chk1 in Xenopus oocytes. Dev Biol 2001; 229:250-61. [PMID: 11133168 DOI: 10.1006/dbio.2000.9968] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Chk1, a nuclear DNA damage/replication G2 checkpoint kinase, phosphorylates Cdc25 and causes its nuclear exclusion in yeast and mammalian cells, thereby arresting the cell at the G2 phase until DNA repair/replication is completed. Chk1 is also involved, at least in part, in the natural G2 arrest of immature Xenopus oocytes, but it is unknown how Chk1 inhibits Cdc25 function and undergoes regulation during oocyte maturation. By using enucleated oocytes, we show here that Chk1 inhibits Cdc25 function in the cytoplasm of G2-arrested oocytes and that Cdc25 is activated exclusively in the cytoplasm of maturing oocytes. Moreover, we show that Chk1 activity is not appreciably altered during maturation, being maintained at basal levels, and that C-terminal truncation mutants of Chk1 have very high kinase activities, strong abilities to inhibit maturation, and altered subcellular localization in oocytes. These results, together with other results, suggest that the Chk1/Cdc25 pathway is involved cytoplasmically in G2 arrest of Xenopus oocytes, but moderately and independent of the G2 checkpoint, and that the C-terminal region of Chk1 negatively regulates its kinase activity and also determines its subcellular localization. Based on these results, we discuss the possibility that Chk1 (with the basal activity) may function as an ordinary regulator of Cdc25 in oocytes (and in other cell types) and that Chk1 might be hyperactivated in response to the G2 checkpoint via its dramatic conformational change.
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Affiliation(s)
- T Oe
- Department of Biology, Graduate School of Sciences, Kyushu University, Hakozaki 6-10-1, Fukuoka, 812-8581, Japan
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43
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Griffiths DJ, Liu VF, Nurse P, Wang TS. Role of fission yeast primase catalytic subunit in the replication checkpoint. Mol Biol Cell 2001; 12:115-28. [PMID: 11160827 PMCID: PMC30572 DOI: 10.1091/mbc.12.1.115] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2000] [Revised: 10/13/2000] [Accepted: 10/30/2000] [Indexed: 11/11/2022] Open
Abstract
To investigate the cell cycle checkpoint response to aberrant S phase-initiation, we analyzed mutations of the two DNA primase subunit genes of Schizosaccharomyces pombe, spp1(+) and spp2(+) (S. pombe primase 1 and 2). spp1(+) encodes the catalytic subunit that synthesizes the RNA primer, which is then utilized by Polalpha to synthesize the initiation DNA. Here, we reported the isolation of the fission yeast spp1(+) gene and cDNA and the characterization of Spp1 protein and its cellular localization during the cell cycle. Spp1 is essential for cell viability, and thermosensitive mutants of spp1(+) exhibit an allele-specific abnormal mitotic phenotype. Mutations of spp1(+) reduce the steady-state cellular levels of Spp1 protein and compromised the formation of Polalpha-primase complex. The spp1 mutant displaying an aberrant mitotic phenotype also fails to properly activate the Chk1 checkpoint kinase, but not the Cds1 checkpoint kinase. Mutational analysis of Polalpha has previously shown that activation of the replication checkpoint requires the initiation of DNA synthesis by Polalpha. Together, these have led us to propose that suboptimal cellular levels of polalpha-primase complex due to the allele-specific mutations of Spp1 might not allow Polalpha to synthesize initiation DNA efficiently, resulting in failure to activate a checkpoint response. Thus, a functional Spp1 is required for the Chk1-mediated, but not the Cds1-mediated, checkpoint response after an aberrant initiation of DNA synthesis.
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Affiliation(s)
- D J Griffiths
- Department of Pathology, Stanford University School of Medicine, Stanford, California 94305-5324, USA
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44
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Cortes-Bratti X, Chaves-Olarte E, Lagergård T, Thelestam M. Cellular internalization of cytolethal distending toxin from Haemophilus ducreyi. Infect Immun 2000; 68:6903-11. [PMID: 11083812 PMCID: PMC97797 DOI: 10.1128/iai.68.12.6903-6911.2000] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The chancroid bacterium Haemophilus ducreyi produces a toxin (HdCDT) which is a member of the recently discovered family of cytolethal distending toxins (CDTs). These protein toxins prevent the cyclin-dependent kinase cdc2 from being activated, thus blocking the transition of cells from the G(2) phase into mitosis, with the consequent arrest of intoxicated cells in G(2). It is not known whether these toxins act by signaling from the cell surface or intracellularly only. Here we report that HdCDT has to undergo at least internalization before being able to act. Cellular intoxication was inhibited (i) by removal of clathrin coats via K(+) depletion, (ii) by treatment with drugs that inhibit receptor clustering into coated pits, and (iii) in cells genetically manipulated to fail in clathrin-dependent endocytosis. Intoxication was also completely inhibited in cells treated with bafilomycin A1 or nocodazole and in cells incubated at 18 degrees C, i.e., under conditions known to block the fusion of early endosomes with downstream compartments. Moreover, disruption of the Golgi complex by treatment with brefeldin A or ilimaquinone blocked intoxication. In conclusion, our data indicate that HdCDT enters cells via clathrin-coated pits and has to be transported via the Golgi complex in order to intoxicate cells. This is the first member of the family of CDTs for which cellular internalization and some details of the pathway have been demonstrated.
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Affiliation(s)
- X Cortes-Bratti
- Microbiology and Tumorbiology Center, Karolinska Institutet, S-171 77 Stockholm, Sweden
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45
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Rhind N, Russell P. Chk1 and Cds1: linchpins of the DNA damage and replication checkpoint pathways. J Cell Sci 2000; 113 ( Pt 22):3889-96. [PMID: 11058076 PMCID: PMC2863124 DOI: 10.1242/jcs.113.22.3889] [Citation(s) in RCA: 161] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Recent work on the mechanisms of DNA damage and replication cell cycle checkpoints has revealed great similarity between the checkpoint pathways of organisms as diverse as yeasts, flies and humans. However, there are differences in the ways these organisms regulate their cell cycles. To connect the conserved checkpoint pathways with various cell cycle targets requires an adaptable link that can target different cell cycle components in different organisms. The Chk1 and Cds1 protein kinases, downstream effectors in the checkpoint pathways, seem to play just such roles. Perhaps more surprisingly, the two kinases not only have different targets in different organisms but also seem to respond to different signals in different organisms. So, whereas in fission yeast Chk1 is required for the DNA damage checkpoint and Cds1 is specifically involved in the replication checkpoint, their roles seem to be shuffled in metazoans.
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46
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Sugimoto K, Tamayose K, Takagi M, Yamada K, Sasaki M, Mizutani S, Oshimi K. Activation of an ataxia telangiectasia mutation-dependent intra-S-phase checkpoint by anti-tumour drugs in HL-60 and human lymphoblastoid cells. Br J Haematol 2000; 110:819-25. [PMID: 11054063 DOI: 10.1046/j.1365-2141.2000.02304.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In yeast cells, the intra-S-phase checkpoint slows down the rate of DNA replication in response to DNA damage. Here we showed that a similar checkpoint mechanism is present and activated by anti-tumour drugs in HL-60 and Epstein-Barr virus (EBV)-transformed human lymphoblastoid cells. Using bromodeoxyuridine (BrdU) pulse labelling combined with two-dimensional flow cytometric analysis, we clearly visualized the cell-cycle progression of the BrdU-positive population (cells originally belonging to the S phase) and detected even subtle changes in S-phase progression induced by mild drug treatment conditions free of apoptosis. The DNA topoisomerase II inhibitors, doxorubicin and etoposide (250 nmol/l and 400 nmol/l, respectively, for 8 h), retained the BrdU-positive HL-60 cells in the latter half of S and G2/M positions, and the pyrimidine analogue anti-metabolite, cytosine beta-D-arabinofuranose (Ara-C; 50 nmol/l), kept them in early-to-late S phase after 8 h of incubation. Because 10 micromol/l of caffeine added 2 h later attenuated the S-phase retardation by these drugs in HL-60 cells, slowing of the S-phase progression should be actively regulated. Furthermore, two ataxia telangiectasia (AT)-derived lymphoblastoid cell lines were impaired in the doxorubicin-induced S-phase retardation, which indicated that the process is at least partially dependent on ataxia telangiectasia mutated (ATM) gene product. The inhibitory mechanism on S-phase progression elicited by anti-tumour drugs in HL-60 and lymphoblastoid cells may therefore correspond to the intra-S-phase checkpoint of the yeast cells.
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Affiliation(s)
- K Sugimoto
- Department of Haematology, Juntendo University School of Medicine, Tokyo, Japan.
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47
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Wilson DW, Lamé MW, Dunston SK, Segall HJ. DNA damage cell checkpoint activities are altered in monocrotaline pyrrole-induced cell cycle arrest in human pulmonary artery endothelial cells. Toxicol Appl Pharmacol 2000; 166:69-80. [PMID: 10896848 DOI: 10.1006/taap.2000.8966] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Monocrotaline pyrrole (MCTP) causes cyto- and karyomegaly and persistent cell cycle arrest in the G2 stage of the cell cycle in cultured bovine pulmonary artery endothelial cells. To better characterize the cell cycle regulatory mechanisms of this process as well as determine whether this process would occur in cells of human origin, we treated human pulmonary artery endothelial cell (HPAEC) cultures with MCTP and determined, by flow cytometry, the expression of cyclin B1 and p53 in conjunction with DNA content. We also validated by Western blots that the persistence of cdc2 in its inactivated phosphorylated state, previously described in bovine cell cultures, occurred in HPAEC. Alterations in p53, cyclin A, cyclin B1, and cdc25c expression were also examined in Western blots of treated HPAEC extracts. The response of HPAEC to MCTP was compared with that of adriamycin and nocodazole, agents known to cause cell cycle alterations. Results of these experiments demonstrate that HPAEC treated with MCTP develop a population of cells in G2 that has increased cyclin B1 expression. These cells express increased amounts of cdc2 but not cdc25c. The ratio of inactive triphosphorylated cdc2 to the active monophosphorylated form increased moderately from control cultures in contrast to predominance of the active form in nocodazole-treated cultures. In addition, a second population of cells expressing cyclin B1 had continued incorporation of BrdU and DNA content consistent with 8 N chromosomes. A similar 8 N cell population was evident in nocodazole-treated cells but these cells had both cyclin B1 positive and negative components. Compared with adriamycin, a known inducer of p53, MCTP-treated HPAEC expressed p53 only at high concentrations and p53 expression was not coordinated with G2 arrest or polyploidy. We conclude that HPAEC treated with low concentrations of MCTP develop G2 arrest in association with persistent cyclin B1 expression, failure to completely activate cdc2, and continued DNA synthesis through a pathway that is unrelated to altered expression of p53.
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Affiliation(s)
- D W Wilson
- Department of Veterinary Pathology, Microbiology, and Immunology, University of California at Davis, Davis, California 95616, USA.
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48
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Houston CT, Taylor WP, Widlanski TS, Reilly JP. Investigation of enzyme kinetics using quench-flow techniques with MALDI-TOF mass spectrometry. Anal Chem 2000; 72:3311-9. [PMID: 10939405 DOI: 10.1021/ac991499m] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry is combined off-line with rapid chemical quench-flow methods to investigate the pre-steady-state kinetics of a protein-tyrosine phosphatase (PTPase). PTPase kinetics are generally interrogated spectrophotometrically by the employment of an artificial, chromophoric substrate. However, that methodology places a constraint on the experiment, hampering studies of natural, biochemically relevant substrates that do not incorporate a chromophore. The mass spectrometric assay reported herein is based on the formation of a covalent phosphoenzyme intermediate during substrate turnover. This species is generated in the reaction regardless of the substrate studied and has a molecular weight 80 Da greater than that of the native enzyme. By following the appearance of this intermediate in a time-resolved manner, we can successfully measure pre-steady-state kinetics, regardless of the incorporation of a chromophore. The strengths of the mass-spectrometric assay are its uniform response to all substrates, simple and direct detection of covalent enzyme-substrate intermediates, and facile identification of enzyme heterogeneities that may affect enzymatic activity.
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Affiliation(s)
- C T Houston
- Department of Chemistry, Indiana University, Bloomington 47405, USA
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49
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Abstract
The 14-3-3 proteins constitute a family that is highly conserved in a wide range of organisms, including higher eukaryotes, invertebrates and plants. Variants of 14-3-3 proteins assembled in homo- and heterodimers were found to interact with diverse cellular proteins. Until recently, the biological role of 14-3-3 members was still poorly understood. However, the results of an increasing number of studies on their structure and function are converging to define 14-3-3 proteins as a novel type of adaptor that modulates interactions between components involved in signal transduction pathway and in cell cycle control.
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Affiliation(s)
- V Baldin
- Laboratoire de Biologie Cellulaire et Moléculaire du Contrôle de la Prolifération Université Paul Sabatier-CNRS, Toulouse, France
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50
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Abstract
Transgenesis refers to the modification of a genome to carry specified exogenous DNA sequences (transgenes, tgs) in a plant or animal; tgs are ideally transmissible through the germline. It has recently been shown that a membrane-disrupted spermatozoon mixed with exogenous DNA can be microinjected into an unfertilized, metaphase II (mII) oocyte to generate transgenic mouse embryos and offspring. This is here referred to as metaphase II (mII) transgenesis. Exogenous DNA clearly becomes genomically integrated in this process, but how? Presumably, the integration process utilizes DNA repair and recombinational machinery resident within mII oocytes. With recent advances in the description of DNA recombination and repair per se and in relation to meiotic and mitotic cell cycles, we are now poised to explain features of mIl transgenesis. Conversely, the method may of itself provide a new tool to probe these aspects of DNA metabolism. This article describes mil transgenesis in the context of DNA recombination and homeostasis in mII oocytes. A fuller understanding of the underlying recombinational mechanisms may enable improved methods of manipulating mammalian genomes and lead to gene targeting and genetic surgery in mII oocytes.
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Affiliation(s)
- A C Perry
- Laboratory of Developmental Biology and Neurogenetics, The Rockefeller University, New York, New York 10021, USA.
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