101
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Ziai JM, Siddon AJ. Pathology Consultation on Gene Mutations in Acute Myeloid Leukemia. Am J Clin Pathol 2015; 144:539-54. [PMID: 26386075 DOI: 10.1309/ajcp77zfpuqgygwy] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
OBJECTIVES Acute myeloid leukemia (AML) is a rapidly fatal disease without the use of aggressive chemotherapy regimens. Cytogenetic and molecular studies are commonly used to classify types of AML based on prognosis, as well as to determine therapeutic regimens. METHODS Although there are several AML classifications determined by particular translocations, cytogenetically normal AML represents a molecularly, as well as clinically, heterogeneous group of diseases. Laboratory evaluation of AML will become increasingly important as new mutations with both prognostic and therapeutic implications are being recognized. Moreover, because many patients with AML are being treated more effectively, these mutations may become increasingly useful as markers of minimal residual disease, which can be interpreted in an individualized approach. RESULTS Current laboratory studies of gene mutations in AML include analysis of NPM1, FLT3, CEBPA, and KIT. In addition to these genes, many other genes are emerging as potentially useful in determining patients' prognosis, therapy, and disease course. CONCLUSIONS This article briefly reviews the current most clinically relevant gene mutations and their clinical and immunophenotypic features, prognostic information, and methods used for detection.
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Affiliation(s)
| | - Alexa J. Siddon
- Departments of Pathology, Yale School of Medicine, New Haven, CT
- Laboratory Medicine, Yale School of Medicine, New Haven, CT
- VA Connecticut Healthcare, West Haven, CT
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102
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Chen J, Sun J, Yang L, Yan Y, Shi W, Shi J, Huang Q, Chen J, Lan Q. Upregulation of B23 promotes tumor cell proliferation and predicts poor prognosis in glioma. Biochem Biophys Res Commun 2015; 466:124-30. [PMID: 26343305 DOI: 10.1016/j.bbrc.2015.08.118] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Accepted: 08/26/2015] [Indexed: 12/13/2022]
Abstract
B23 (also known as Nucleophosmin, NPM, numatrin or NO38) is a ubiquitously expressed phosphoprotein belonging to the nucleoplasmin family of chaperones. In this study we intended to investigate the clinical significance of B23 expression in human glioma and its biological function in glioma cells. Western blot and immunohistochemistry analysis showed that B23 was overexpressed in glioma tissues and glioma cell lines. In addition, the expression level of B23 was positively correlated with glioma pathological grade and Ki-67 expression. Kaplan-Meier analysis revealed that a higher B23 expression in patients with glioma was associated with a poorer prognosis. In vitro, after the release of glioma cell lines from serum starvation, the expression of B23 was upregulated, as well as PCNA (Proliferating Cell Nuclear Antigen) and cyclin A. In addition, knockdown of B23 by small interfering RNA transfection diminished the expression of PCNA, cyclin D1 and arrested cell growth at G1 phase. Taken together, our results implied that B23 could be a candidate prognostic biomarker as well as a potential therapeutical target of glioma.
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Affiliation(s)
- Jianguo Chen
- Department of Neurosurgery, The Second Affiliated Hospital of Soochow University, 1055 Sanxiang Road, Suzhou, 215004, Jiangsu Province, China; Department of Neurosurgery, Affiliated Hospital of Nantong University, 20 Xisi Road, Nantong, 226001, Jiangsu Province, China
| | - Jie Sun
- Department of Neurosurgery, Affiliated Hospital of Nantong University, 20 Xisi Road, Nantong, 226001, Jiangsu Province, China
| | - Liu Yang
- Department of Neurosurgery, Affiliated Hospital of Nantong University, 20 Xisi Road, Nantong, 226001, Jiangsu Province, China
| | - Yaohua Yan
- Department of Neurosurgery, Affiliated Hospital of Nantong University, 20 Xisi Road, Nantong, 226001, Jiangsu Province, China
| | - Wei Shi
- Department of Neurosurgery, Affiliated Hospital of Nantong University, 20 Xisi Road, Nantong, 226001, Jiangsu Province, China
| | - Jinlong Shi
- Department of Neurosurgery, Affiliated Hospital of Nantong University, 20 Xisi Road, Nantong, 226001, Jiangsu Province, China
| | - Qingfeng Huang
- Department of Neurosurgery, Affiliated Hospital of Nantong University, 20 Xisi Road, Nantong, 226001, Jiangsu Province, China
| | - Jian Chen
- Department of Neurosurgery, Affiliated Hospital of Nantong University, 20 Xisi Road, Nantong, 226001, Jiangsu Province, China
| | - Qing Lan
- Department of Neurosurgery, The Second Affiliated Hospital of Soochow University, 1055 Sanxiang Road, Suzhou, 215004, Jiangsu Province, China.
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103
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Kim JY, Cho YE, Park JH. The Nucleolar Protein GLTSCR2 Is an Upstream Negative Regulator of the Oncogenic Nucleophosmin-MYC Axis. THE AMERICAN JOURNAL OF PATHOLOGY 2015; 185:2061-8. [DOI: 10.1016/j.ajpath.2015.03.016] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Revised: 02/13/2015] [Accepted: 03/19/2015] [Indexed: 11/16/2022]
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104
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Wang J, Ding S, Duan Z, Xie Q, Zhang T, Zhang X, Wang Y, Chen X, Zhuang H, Lu F. Role of p14ARF-HDM2-p53 axis in SOX6-mediated tumor suppression. Oncogene 2015; 35:1692-702. [PMID: 26119940 PMCID: PMC4820682 DOI: 10.1038/onc.2015.234] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Revised: 05/05/2015] [Accepted: 05/10/2015] [Indexed: 12/12/2022]
Abstract
Sex-determining region Y box 6 (SOX6) has been described as a tumor-suppressor gene in several cancers. Our previous work has suggested that SOX6 upregulated p21Waf1/Cip1(p21) expression in a p53-dependent manner; however, the underlying mechanism has remained elusive. In this study, we confirmed that SOX6 can suppress cell proliferation in vitro and in vivo by stabilizing p53 protein and subsequently upregulating p21. Co-immunoprecipitation and immunocytofluorescence assays demonstrated that SOX6 can promote formation of the p14ARF-HDM2-p53 ternary complex by promoting translocation of p14ARF (p14 alternate reading frame tumor suppressor) to the nucleoplasm, thereby inhibiting HDM2-mediated p53 nuclear export and degradation. Chromatin immunoprecipitation combined with PCR assay proved that SOX6 can bind to a potential binding site in the regulatory region of the c-Myc gene. Furthermore, we confirmed that SOX6 can downregulate the expression of c-Myc, as well as its direct target gene nucleophosmin 1 (NPM1), and that the SOX6-induced downregulation of NPM1 is linked to translocation of p14ARF to the nucleoplasm. Finally, we showed that the highly conserved high-mobility group (HMG) domain of SOX6 is required for SOX6-mediated p53 stabilization and tumor inhibitory activity. Collectively, these results reveal a new mechanism of SOX6-mediated tumor suppression involving p21 upregulation via the p14ARF-HDM2-p53 axis in an HMG domain-dependent manner.
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Affiliation(s)
- J Wang
- Department of Microbiology and Infectious Disease Center, School of Basic Medicine, Peking University Health Science Center, Beijing, China
| | - S Ding
- Department of Microbiology and Infectious Disease Center, School of Basic Medicine, Peking University Health Science Center, Beijing, China
| | - Z Duan
- Department of Microbiology and Infectious Disease Center, School of Basic Medicine, Peking University Health Science Center, Beijing, China
| | - Q Xie
- Department of Microbiology and Infectious Disease Center, School of Basic Medicine, Peking University Health Science Center, Beijing, China
| | - T Zhang
- Department of Microbiology and Infectious Disease Center, School of Basic Medicine, Peking University Health Science Center, Beijing, China
| | - X Zhang
- Department of Microbiology and Infectious Disease Center, School of Basic Medicine, Peking University Health Science Center, Beijing, China
| | - Y Wang
- Department of Microbiology and Infectious Disease Center, School of Basic Medicine, Peking University Health Science Center, Beijing, China
| | - X Chen
- Department of Microbiology and Infectious Disease Center, School of Basic Medicine, Peking University Health Science Center, Beijing, China
| | - H Zhuang
- Department of Microbiology and Infectious Disease Center, School of Basic Medicine, Peking University Health Science Center, Beijing, China
| | - F Lu
- Department of Microbiology and Infectious Disease Center, School of Basic Medicine, Peking University Health Science Center, Beijing, China
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105
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de Las Heras-Rubio A, Perucho L, Paciucci R, Vilardell J, LLeonart ME. Ribosomal proteins as novel players in tumorigenesis. Cancer Metastasis Rev 2015; 33:115-41. [PMID: 24375388 DOI: 10.1007/s10555-013-9460-6] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Ribosome biogenesis is the most demanding energetic and metabolic expenditure of the cell. The nucleolus, a nuclear compartment, coordinates rRNA transcription, maturation, and assembly into ribosome subunits. The transcription process is highly coordinated with ribosome biogenesis. In this context, ribosomal proteins (RPs) play a crucial role. In the last decade, an increasing number of studies have associated RPs with extraribosomal functions related to proliferation. Importantly, the expression of RPs appears to be deregulated in several human disorders due, at least in part, to genetic mutations. Although the deregulation of RPs in human malignancies is commonly observed, a more complex mechanism is believed to be involved, favoring the tumorigenic process, its progression and metastasis. This review explores the roles of the most frequently mutated oncogenes and tumor suppressor genes in human cancer that modulate ribosome biogenesis, including their interaction with RPs. In this regard, we propose a new focus for novel therapies.
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Affiliation(s)
- A de Las Heras-Rubio
- Oncology and Pathology Group, Institut de Recerca Hospital Vall d'Hebron, Passeig Vall d'Hebron 119-129, 08035, Barcelona, Spain
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106
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Kumazawa T, Nishimura K, Katagiri N, Hashimoto S, Hayashi Y, Kimura K. Gradual reduction in rRNA transcription triggers p53 acetylation and apoptosis via MYBBP1A. Sci Rep 2015; 5:10854. [PMID: 26044764 PMCID: PMC4456663 DOI: 10.1038/srep10854] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Accepted: 05/05/2015] [Indexed: 12/19/2022] Open
Abstract
The nucleolus, whose primary function is ribosome biogenesis, plays an essential role in p53 activation. Ribosome biogenesis is inhibited in response to cellular stress and several nucleolar proteins translocate from the nucleolus to the nucleoplasm, where they activate p53. In this study, we analysed precisely how impaired ribosome biogenesis regulates the activation of p53 by depleting nucleolar factors involved in rRNA transcription or rRNA processing. Nucleolar RNA content decreased when rRNA transcription was inhibited. In parallel with the reduced levels of nucleolar RNA content, the nucleolar protein Myb-binding protein 1 A (MYBBP1A) translocated to the nucleoplasm and increased p53 acetylation. The acetylated p53 enhanced p21 and BAX expression and induced apoptosis. In contrast, when rRNA processing was inhibited, MYBBP1A remained in the nucleolus and nonacetylated p53 accumulated, causing cell cycle arrest at the G1 phase by inducing p21 but not BAX. We propose that the nucleolus functions as a stress sensor to modulate p53 protein levels and its acetylation status, determining cell fate between cell cycle arrest and apoptosis by regulating MYBBP1A translocation.
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Affiliation(s)
- Takuya Kumazawa
- 1] Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennnoudai, Tsukuba 305-8577, Japan [2] First Department of Internal Medicine, Nara Medical University, 840 Shijo-cho Kashihara, Nara 634-8522, Japan
| | - Kazuho Nishimura
- Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennnoudai, Tsukuba 305-8577, Japan
| | - Naohiro Katagiri
- Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennnoudai, Tsukuba 305-8577, Japan
| | - Sayaka Hashimoto
- Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennnoudai, Tsukuba 305-8577, Japan
| | - Yuki Hayashi
- Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennnoudai, Tsukuba 305-8577, Japan
| | - Keiji Kimura
- Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennnoudai, Tsukuba 305-8577, Japan
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107
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Li Z, Shi K, Guan L, Jiang Q, Yang Y, Xu C. Activation of p53 by sodium selenite switched human leukemia NB4 cells from autophagy to apoptosis. Oncol Res 2015; 21:325-31. [PMID: 25198662 DOI: 10.3727/096504014x14024160459087] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
It was revealed by our previous research that sodium selenite repressed autophagy accompanied by the induction of apoptosis in human leukemia NB4 cells. The inhibition of autophagy exerted a facilitative effect on apoptosis. In the present study, we further explored the mechanisms underlying the switch from autophagy to apoptosis and elucidated p53 played a key role. Selenite induced phosphorylation of p53 at the vital site Ser15 via p38MAPK and ERK. Subsequently p53 dissociated with its inhibitory protein mouse double minute 2 (MDM2). Meanwhile, the nucleolar protein B23 transferred from the nucleolus to the nucleoplasm and associated with MDM2, probably stabilizing p53. The active p53 participated in the decrease of autophagic protein Beclin-1 and LC-3, as well as activation of apoptosis-related caspases. Furthermore, in p53 mutant U937 leukemia cells, selenite could not elicit such a switch from autophagy to apoptosis, laying emphasis on the crucial role p53 played in this process.
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Affiliation(s)
- Zhushi Li
- State Key Laboratory of Medical Molecular Biology, Department of Biochemistry and Molecular Biology, Institute of Basic Medical Sciences and School of Basic Medicine, Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing, China
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108
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Marcar L, Ihrig B, Hourihan J, Bray SE, Quinlan PR, Jordan LB, Thompson AM, Hupp TR, Meek DW. MAGE-A Cancer/Testis Antigens Inhibit MDM2 Ubiquitylation Function and Promote Increased Levels of MDM4. PLoS One 2015; 10:e0127713. [PMID: 26001071 PMCID: PMC4441487 DOI: 10.1371/journal.pone.0127713] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Accepted: 04/17/2015] [Indexed: 02/04/2023] Open
Abstract
Melanoma antigen A (MAGE-A) proteins comprise a structurally and biochemically similar sub-family of Cancer/Testis antigens that are expressed in many cancer types and are thought to contribute actively to malignancy. MAGE-A proteins are established regulators of certain cancer-associated transcription factors, including p53, and are activators of several RING finger-dependent ubiquitin E3 ligases. Here, we show that MAGE-A2 associates with MDM2, a ubiquitin E3 ligase that mediates ubiquitylation of more than 20 substrates including mainly p53, MDM2 itself, and MDM4, a potent p53 inhibitor and MDM2 partner that is structurally related to MDM2. We find that MAGE-A2 interacts with MDM2 via the N-terminal p53-binding pocket and the RING finger domain of MDM2 that is required for homo/hetero-dimerization and for E2 ligase interaction. Consistent with these data, we show that MAGE-A2 is a potent inhibitor of the E3 ubiquitin ligase activity of MDM2, yet it does not have any significant effect on p53 turnover mediated by MDM2. Strikingly, however, increased MAGE-A2 expression leads to reduced ubiquitylation and increased levels of MDM4. Similarly, silencing of endogenous MAGE-A expression diminishes MDM4 levels in a manner that can be rescued by the proteasomal inhibitor, bortezomid, and permits increased MDM2/MDM4 association. These data suggest that MAGE-A proteins can: (i) uncouple the ubiquitin ligase and degradation functions of MDM2; (ii) act as potent inhibitors of E3 ligase function; and (iii) regulate the turnover of MDM4. We also find an association between the presence of MAGE-A and increased MDM4 levels in primary breast cancer, suggesting that MAGE-A-dependent control of MDM4 levels has relevance to cancer clinically.
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Affiliation(s)
- Lynnette Marcar
- Division of Cancer Research, University of Dundee, Clinical Research Centre and Jacqui Wood Cancer Centre, Ninewells Hospital, James Arrott Drive, Dundee, United Kingdom
| | - Bianca Ihrig
- Division of Cancer Research, University of Dundee, Clinical Research Centre and Jacqui Wood Cancer Centre, Ninewells Hospital, James Arrott Drive, Dundee, United Kingdom
| | - John Hourihan
- Division of Cancer Research, University of Dundee, Clinical Research Centre and Jacqui Wood Cancer Centre, Ninewells Hospital, James Arrott Drive, Dundee, United Kingdom
| | - Susan E. Bray
- Division of Cancer Research, University of Dundee, Clinical Research Centre and Jacqui Wood Cancer Centre, Ninewells Hospital, James Arrott Drive, Dundee, United Kingdom
| | - Philip R. Quinlan
- School of Veterinary Medicine and Science, University of Nottingham, Sutton Bonington Campus, Leicestershire, United Kingdom
- School of Computer Science, University of Nottingham, Jubilee Campus, Nottingham, United Kingdom
- Advanced Data Analysis Centre, University of Nottingham, Nottingham, United Kingdom
| | - Lee B. Jordan
- Division of Cancer Research, University of Dundee, Clinical Research Centre and Jacqui Wood Cancer Centre, Ninewells Hospital, James Arrott Drive, Dundee, United Kingdom
| | - Alastair M. Thompson
- M. D. Anderson Cancer Center, University of Texas, 1400 Pressler Drive, Unit 1484, Houston, United States of America
| | - Ted R. Hupp
- p53 Signal Transduction Laboratory, Edinburgh Cancer Research UK Centre, The University of Edinburgh, Crewe Road South, Edinburgh, United Kingdom
| | - David W. Meek
- Division of Cancer Research, University of Dundee, Clinical Research Centre and Jacqui Wood Cancer Centre, Ninewells Hospital, James Arrott Drive, Dundee, United Kingdom
- * E-mail:
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109
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Pfister JA, D'Mello SR. Insights into the regulation of neuronal viability by nucleophosmin/B23. Exp Biol Med (Maywood) 2015; 240:774-86. [PMID: 25908633 DOI: 10.1177/1535370215579168] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The vastness of the neuronal network that constitutes the human brain proves challenging when trying to understand its complexity. Furthermore, due to the senescent state they enter into upon maturation, neurons lack the ability to regenerate in the face of insult, injury or death. Consequently, their excessive death can be detrimental to the proper functioning of the brain. Therefore, elucidating the mechanisms regulating neuronal survival is, while challenging, of great importance as the incidence of neurological disease is becoming more prevalent in today's society. Nucleophosmin/B23 (NPM) is an abundant and ubiquitously expressed protein that regulates vital cellular processes such as ribosome biogenesis, cell proliferation and genomic stability. As a result, it is necessary for proper embryonic development, but has also been implicated in many cancers. While highly studied in the context of proliferative cells, there is a lack of understanding NPM's role in post-mitotic neurons. By exploring its role in healthy neurons as well as its function in the regulation of cell death and neurodegeneration, there can be a better understanding of how these diseases initiate and progress. Owing to what is thus far known about its function in the cell, NPM could be an attractive therapeutic target in the treatment of neurodegenerative diseases.
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Affiliation(s)
- Jason A Pfister
- Department of Biological Sciences, University of Texas at Dallas, Richardson, TX 75080, USA Department of Biological Sciences, Southern Methodist University, Dallas, TX 75275, USA
| | - Santosh R D'Mello
- Department of Biological Sciences, Southern Methodist University, Dallas, TX 75275, USA
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110
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Kim JY, Cho YE, An YM, Kim SH, Lee YG, Park JH, Lee S. GLTSCR2 is an upstream negative regulator of nucleophosmin in cervical cancer. J Cell Mol Med 2015; 19:1245-52. [PMID: 25818168 PMCID: PMC4459840 DOI: 10.1111/jcmm.12474] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Accepted: 09/24/2014] [Indexed: 11/29/2022] Open
Abstract
Nucleophosmin (NPM)/B23, a multifunctional nucleolar phosphoprotein, plays an important role in ribosome biogenesis, cell cycle regulation, apoptosis and cancer pathogenesis. The role of NPM in cells is determined by several factors, including total expression level, oligomerization or phosphorylation status, and subcellular localization. In the nucleolus, NPM participates in rRNA maturation to enhance ribosomal biogenesis. Consistent with this finding, NPM expression is increased in rapidly proliferating cells and many types of human cancers. In response to ribosomal stress, NPM is redistributed to the nucleoplasm, where it inactivates mouse double minute 2 homologue to stabilize p53 and inhibit cell cycle progression. These observations indicate that nucleolus-nucleoplasmic mobilization of NPM is one of the key molecular mechanisms that determine the role of NPM within the cell. However, the regulatory molecule(s) that control(s) NPM stability and subcellular localization, crucial to the pluripotency of intercellular NPM, remain(s) unidentified. In this study, we showed that nucleolar protein GLTSCR2/Pict-1 induced nucleoplasmic translocation and enhanced the degradation of NPM via the proteasomal polyubiquitination pathway. In addition, we showed that GLTSCR2 expression decreased the transforming activity of cells mediated by NPM and that the expression of NPM is reciprocally related to that of GLTSCR2 in cervical cancer tissue. In this study, we demonstrated that GLTSCR2 is an upstream negative regulator of NPM.
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Affiliation(s)
- Jee-Youn Kim
- Department of Pathology, College of Medicine, Kyung Hee University, Seoul, Korea
| | - Young-Eun Cho
- Department of Pathology, College of Medicine, Kyung Hee University, Seoul, Korea
| | - Yong-Min An
- Department of Pathology, College of Medicine, Kyung Hee University, Seoul, Korea
| | - Sang-Hoon Kim
- Department of Pathology, College of Medicine, Kyung Hee University, Seoul, Korea
| | - Yong-Gwan Lee
- Department of Pathology, College of Medicine, Kyung Hee University, Seoul, Korea
| | - Jae-Hoon Park
- Department of Pathology, College of Medicine, Kyung Hee University, Seoul, Korea
| | - Sun Lee
- Department of Pathology, College of Medicine, Kyung Hee University, Seoul, Korea
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111
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Mukherjee H, Chan KP, Andresen V, Hanley ML, Gjertsen BT, Myers AG. Interactions of the natural product (+)-avrainvillamide with nucleophosmin and exportin-1 Mediate the cellular localization of nucleophosmin and its AML-associated mutants. ACS Chem Biol 2015; 10:855-63. [PMID: 25531824 PMCID: PMC4652655 DOI: 10.1021/cb500872g] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Nucleophosmin (NPM1) is a multifunctional phosphoprotein localized predominantly within the nucleoli of eukaryotic cells. Mutations within its C-terminal domain are frequently observed in patients with acute myeloid leukemia (AML), are thought to play a key role in the initiation of the disease, and result in aberrant, cytoplasmic localization of the mutant protein. We have previously shown that the electrophilic antiproliferative natural product (+)-avrainvillamide (1) binds to proteins, including nucleophosmin, by S-alkylation of cysteine residues. Here, we report that avrainvillamide restores nucleolar localization of certain AML-associated mutant forms of NPM1 and provide evidence that this relocalization is mediated by interactions of avrainvillamide with mutant NPM1 and exportin-1 (Crm1). Immunofluorescence and mass spectrometric experiments employing a series of different NPM1 constructs suggest that a specific interaction between avrainvillamide and Cys275 of certain NPM1 mutants mediates the relocalization of these proteins to the nucleolus. Avrainvillamide treatment is also shown to inhibit nuclear export of Crm1 cargo proteins, including AML-associated NPM1 mutants. We also observe that avrainvillamide treatment displaces Thr199-phosphorylated NPM1 from duplicated centrosomes, leads to an accumulation of supernumerary centrosomes, and inhibits dephosphorylation of Thr199-phosphorylated NPM1 by protein phosphatase 1. Avrainvillamide is the first small molecule reported to relocalize specific cytoplasmic AML-associated NPM1 mutants to the nucleolus, providing an important demonstration of principle that small molecule induction of a wild-type NPM1 localization phenotype is feasible in certain human cancer cells.
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Affiliation(s)
- Herschel Mukherjee
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States
| | - Kok-Ping Chan
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States
| | - Vibeke Andresen
- Centre for Cancer Biomarkers, CCBIO, Department of Clinical Science, University of Bergen, Bergen, Norway
| | - Mariah L. Hanley
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States
| | - Bjørn Tore Gjertsen
- Centre for Cancer Biomarkers, CCBIO, Department of Clinical Science, University of Bergen, Bergen, Norway
- Department of Internal Medicine, Hematology Section, Haukeland University Hospital, Bergen, Norway
| | - Andrew G. Myers
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States
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112
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Liu M, Varela-Ramirez A, Li J, Dai L, Aguilera RJ, Zhang JY. Humoral autoimmune response to nucleophosmin in the immunodiagnosis of hepatocellular carcinoma. Oncol Rep 2015; 33:2245-52. [PMID: 25779011 PMCID: PMC4391589 DOI: 10.3892/or.2015.3854] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Accepted: 01/26/2015] [Indexed: 02/07/2023] Open
Abstract
Hepatocellular carcinoma (HCC) is a worldwide prevalent cancer with an exremely poor prognosis. Detection of serum α-fetoprotein (AFP) and liver imaging techniques are the conventional methods used clinically for the identification of this malignancy. However, these techniques are not reliable for early diagnosis, and particularly the sensitivity and specificity of AFP in HCC diagnosis are not optimal. Therefore, there is an urgent need for the development of more sensitive and specific methods that can improve AFP quantification in the early detection of HCC. In the present study, autoantibody responses to nucleophosmin (NPM1) in HCC patients were evaluated by enzyme-linked immunosorbent assay (ELISA), western blotting and indirect immunofluorescence. Immunohistochemistry (IHC) with tissue array slides was also performed to analyze protein expression of NPM1 in HCC and control tissues. The prevalence of autoantibodies against NPM1 was 22.4% (17/76) in HCC, which was significantly higher than that in sera from patients with liver cirrhosis (LC), chronic hepatitis (CH) and systemic lupus erythematosus (SLE) (P<0.01). The average titer of autoantibodies against NPM1 in HCC sera was higher compared to that in LC, CH, SLE and normal human sera (NHS) (P<0.01). In addition, anti-NMP1 autoantibodies were detected in sera from several HCC patients with serial bleeding samples. A stronger reactive band corresponding to NMP1 was visualized in the western blot analyses, utilizing sera from patients 3–6 months before the clinical diagnosis of HCC. Our data indicate that NPM1 and the anti-NPM1 system may have potential as an early-stage biomarker for HCC screening and diagnosis.
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Affiliation(s)
- Mei Liu
- Department of Biological Sciences and Border Biomedical Research Center, The University of Texas at El Paso, El Paso, TX 79968, USA
| | - Armando Varela-Ramirez
- Department of Biological Sciences and Border Biomedical Research Center, The University of Texas at El Paso, El Paso, TX 79968, USA
| | - Jitian Li
- Department of Biological Sciences and Border Biomedical Research Center, The University of Texas at El Paso, El Paso, TX 79968, USA
| | - Liping Dai
- Department of Biological Sciences and Border Biomedical Research Center, The University of Texas at El Paso, El Paso, TX 79968, USA
| | - Renato J Aguilera
- Department of Biological Sciences and Border Biomedical Research Center, The University of Texas at El Paso, El Paso, TX 79968, USA
| | - Jian-Ying Zhang
- Department of Biological Sciences and Border Biomedical Research Center, The University of Texas at El Paso, El Paso, TX 79968, USA
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113
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Katagiri N, Kuroda T, Kishimoto H, Hayashi Y, Kumazawa T, Kimura K. The nucleolar protein nucleophosmin is essential for autophagy induced by inhibiting Pol I transcription. Sci Rep 2015; 5:8903. [PMID: 25754892 PMCID: PMC4354046 DOI: 10.1038/srep08903] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Accepted: 02/10/2015] [Indexed: 12/19/2022] Open
Abstract
Various cellular stresses activate autophagy, which is involved in lysosomal degradation of cytoplasmic materials for maintaining nutrient homeostasis and eliminating harmful components. Here, we show that RNA polymerase I (Pol I) transcription inhibition induces nucleolar disruption and autophagy. Treatment with autophagy inhibitors or siRNA specific for autophagy-related (ATG) proteins inhibited autophagy but not nucleolar disruption induced by Pol I transcription inhibition, which suggested that nucleolar disruption was upstream of autophagy. Furthermore, treatment with siRNA specific for nucleolar protein nucleophosmin (NPM) inhibited this type of autophagy. This showed that NPM was involved in autophagy when the nucleolus was disrupted by Pol I inhibition. In contrast, NPM was not required for canonical autophagy induced by nutrient starvation, as it was not accompanied by nucleolar disruption. Thus, our results revealed that, in addition to canonical autophagy, there may be NPM-dependent autophagy associated with nucleolar disruption.
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Affiliation(s)
- Naohiro Katagiri
- Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennnoudai, Tsukuba 305-8577, Japan
| | - Takao Kuroda
- Center of Tsukuba Advanced Research Alliance, University of Tsukuba, 1-1-1 Tennnoudai, Tsukuba 305-8577, Japan
| | - Hiroyuki Kishimoto
- 1] Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennnoudai, Tsukuba 305-8577, Japan [2] Center of Tsukuba Advanced Research Alliance, University of Tsukuba, 1-1-1 Tennnoudai, Tsukuba 305-8577, Japan
| | - Yuki Hayashi
- Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennnoudai, Tsukuba 305-8577, Japan
| | - Takuya Kumazawa
- Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennnoudai, Tsukuba 305-8577, Japan
| | - Keiji Kimura
- Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennnoudai, Tsukuba 305-8577, Japan
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Shahab S, Shamsi TS, Ahmed N. Prognostic involvement of nucleophosmin mutations in acute myeloid leaukemia. Asian Pac J Cancer Prev 2015; 14:5615-20. [PMID: 24289551 DOI: 10.7314/apjcp.2013.14.10.5615] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/08/2022] Open
Abstract
Nucleophosmin (NPM1) is a protein of highly conserved nature which works as a molecular chaperone and is mostly found in nucleoli. NPM also involved in the maturation of preribosomes and duplication of centrosomes. Furthermore, it is also active in control and regulation of the ARF-p53 tumor suppressor pathway. A high rate of incidence and prognostic involvement is reported by various authors in AML patients. In AML it behaves as a favorable prognostic marker. NPM mutations are more frequently associated with normal-karyotype AML and are usually absent in patients having abnormal or poor cytogenetic. NPM mutations are not frequent in other hematopoietic tumors .Two main types of mutations have been described to date. Both of these cause abnormal cytoplasmic localization of NPM1. Their high incidence rate in normal karyoptype and their favorable nature make those mutations hot spot or front face mutations which should be checked before treatment starts.
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Affiliation(s)
- Sadaf Shahab
- Molecular Biology, Pure and Applied Research, National Institute Blood Diseases and Bone Marrow Transplantation, Karachi, Pakistan E-mail :
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Stixová L, Sehnalová P, Legartová S, Suchánková J, Hrušková T, Kozubek S, Sorokin DV, Matula P, Raška I, Kovařík A, Fulneček J, Bártová E. HP1β-dependent recruitment of UBF1 to irradiated chromatin occurs simultaneously with CPDs. Epigenetics Chromatin 2014; 7:39. [PMID: 25587355 PMCID: PMC4293114 DOI: 10.1186/1756-8935-7-39] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Accepted: 12/12/2014] [Indexed: 11/24/2022] Open
Abstract
Background The repair of spontaneous and induced DNA lesions is a multistep process. Depending on the type of injury, damaged DNA is recognized by many proteins specifically involved in distinct DNA repair pathways. Results We analyzed the DNA-damage response after ultraviolet A (UVA) and γ irradiation of mouse embryonic fibroblasts and focused on upstream binding factor 1 (UBF1), a key protein in the regulation of ribosomal gene transcription. We found that UBF1, but not nucleolar proteins RPA194, TCOF, or fibrillarin, was recruited to UVA-irradiated chromatin concurrently with an increase in heterochromatin protein 1β (HP1β) level. Moreover, Förster Resonance Energy Transfer (FRET) confirmed interaction between UBF1 and HP1β that was dependent on a functional chromo shadow domain of HP1β. Thus, overexpression of HP1β with a deleted chromo shadow domain had a dominant-negative effect on UBF1 recruitment to UVA-damaged chromatin. Transcription factor UBF1 also interacted directly with DNA inside the nucleolus but no interaction of UBF1 and DNA was confirmed outside the nucleolus, where UBF1 recruitment to DNA lesions appeared simultaneously with cyclobutane pyrimidine dimers; this occurrence was cell-cycle-independent. Conclusions We propose that the simultaneous presence and interaction of UBF1 and HP1β at DNA lesions is activated by the presence of cyclobutane pyrimidine dimers and mediated by the chromo shadow domain of HP1β. This might have functional significance for nucleotide excision repair. Electronic supplementary material The online version of this article (doi:10.1186/1756-8935-7-39) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Lenka Stixová
- Academy of Sciences of the Czech Republic, Institute of Biophysics, v.v.i., Královopolská 135, 612 65 Brno, Czech Republic
| | - Petra Sehnalová
- Academy of Sciences of the Czech Republic, Institute of Biophysics, v.v.i., Královopolská 135, 612 65 Brno, Czech Republic
| | - Soňa Legartová
- Academy of Sciences of the Czech Republic, Institute of Biophysics, v.v.i., Královopolská 135, 612 65 Brno, Czech Republic
| | - Jana Suchánková
- Academy of Sciences of the Czech Republic, Institute of Biophysics, v.v.i., Královopolská 135, 612 65 Brno, Czech Republic
| | - Tereza Hrušková
- Academy of Sciences of the Czech Republic, Institute of Biophysics, v.v.i., Královopolská 135, 612 65 Brno, Czech Republic
| | - Stanislav Kozubek
- Academy of Sciences of the Czech Republic, Institute of Biophysics, v.v.i., Královopolská 135, 612 65 Brno, Czech Republic
| | - Dmitry V Sorokin
- Academy of Sciences of the Czech Republic, Institute of Biophysics, v.v.i., Královopolská 135, 612 65 Brno, Czech Republic ; Faculty of Informatics, Masaryk University, Botanická 68a, 602 00 Brno, Czech Republic
| | - Pavel Matula
- Academy of Sciences of the Czech Republic, Institute of Biophysics, v.v.i., Královopolská 135, 612 65 Brno, Czech Republic ; Faculty of Informatics, Masaryk University, Botanická 68a, 602 00 Brno, Czech Republic
| | - Ivan Raška
- Institute of Cellular Biology and Pathology, the First Faculty of Medicine, Charles University in Prague, Albertov 4, 128 01 Prague, Czech Republic
| | - Aleš Kovařík
- Academy of Sciences of the Czech Republic, Institute of Biophysics, v.v.i., Královopolská 135, 612 65 Brno, Czech Republic
| | - Jaroslav Fulneček
- Academy of Sciences of the Czech Republic, Institute of Biophysics, v.v.i., Královopolská 135, 612 65 Brno, Czech Republic
| | - Eva Bártová
- Academy of Sciences of the Czech Republic, Institute of Biophysics, v.v.i., Královopolská 135, 612 65 Brno, Czech Republic
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Dynamic conformations of nucleophosmin (NPM1) at a key monomer-monomer interface affect oligomer stability and interactions with granzyme B. PLoS One 2014; 9:e115062. [PMID: 25490769 PMCID: PMC4260957 DOI: 10.1371/journal.pone.0115062] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2014] [Accepted: 11/05/2014] [Indexed: 01/02/2023] Open
Abstract
Nucleophosmin (NPM1) is an abundant, nucleolar tumor antigen with important roles in cell proliferation and putative contributions to oncogenesis. Wild-type NPM1 forms pentameric oligomers through interactions at the amino-terminal core domain. A truncated form of NPM1 found in some hepatocellular carcinoma tissue formed an unusually stable oligomer and showed increased susceptibility to cleavage by granzyme B. Initiation of translation at the seventh methionine generated a protein (M7-NPM) that shared all these properties. We used deuterium exchange mass spectrometry (DXMS) to perform a detailed structural analysis of wild-type NPM1 and M7-NPM, and found dynamic conformational shifts or local “unfolding” at a specific monomer-monomer interface which included the β-hairpin “latch.” We tested the importance of interactions at the β-hairpin “latch” by replacing a conserved tyrosine in the middle of the β-hairpin loop with glutamic acid, generating Y67E-NPM. Y67E-NPM did not form stable oligomers and further, prevented wild-type NPM1 oligomerization in a dominant-negative fashion, supporting the critical role of the β-hairpin “latch” in monomer-monomer interactions. Also, we show preferential cleavage by granzyme B at one of two available aspartates (either D161 or D122) in M7-NPM and Y67E-NPM, whereas wild-type NPM1 was cleaved at both sites. Thus, we observed a correlation between the propensity to form oligomers and granzyme B cleavage site selection in nucleophosmin proteins, suggesting that a small change at an important monomer-monomer interface can affect conformational shifts and impact protein-protein interactions.
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117
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Kiran S, Anwar T, Kiran M, Ramakrishna G. Sirtuin 7 in cell proliferation, stress and disease: Rise of the Seventh Sirtuin! Cell Signal 2014; 27:673-82. [PMID: 25435428 DOI: 10.1016/j.cellsig.2014.11.026] [Citation(s) in RCA: 85] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2014] [Accepted: 11/21/2014] [Indexed: 01/23/2023]
Abstract
Sirtuin 7 is a member of the sirtuin family of proteins. Sirtuins were originally discovered in yeast for its role in prolonging replicative lifespan. Until recently SIRT7 happened to be the least studied sirtuin of the seven mammalian sirtuins. However, a number of recent breakthrough reports have provided significant clarity to SIRT7 biology. SIRT7 is now seen as a vital regulator of rRNA and protein synthesis for maintenance of normal cellular homeostasis. Proteins like p53, H3K18, PAF53, NPM1 and GABP-β1 are the known substrates for the deacetylase activity of SIRT7, thereby making it a key mediator of many cellular activities. Studies using in vitro based assays and also knockout mice have revealed a role of SIRT7 in certain disease pathologies as well. High expression of SIRT7 has been reported in few cancer types and is steadily propelling SIRT7 towards an oncogene status. The role of SIRT7 as a pro-survival adaptor molecule in conditions of cellular stress has recently emerged in view of the fact that SIRT7 can regulate molecules like HIF and IRE1α. Additionally, SIRT7 plays a key role in maintenance of the epigenome as it caused the deacetylation of histone (H3K18) and global proteomics studies have shown its interaction with many chromatin remodelling complexes such as B-WICH and other proteins. Lately, the role of SIRT7 in hepatic lipid metabolism has been debated. This review attempts to summarize these recent findings and present the role of SIRT7 as an important cellular regulator.
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Affiliation(s)
- Shashi Kiran
- Laboratory of Cancer Biology, Centre for DNA Fingerprinting and Diagnostics, Hyderabad, Telangana 500001, India
| | - Tarique Anwar
- Laboratory of Cancer Biology, Centre for DNA Fingerprinting and Diagnostics, Hyderabad, Telangana 500001, India
| | - Manjari Kiran
- Laboratory of Computational Biology, Centre for DNA Fingerprinting and Diagnostics, Hyderabad, Telangana 500001, India
| | - Gayatri Ramakrishna
- Laboratory of Cancer Cell Biology, Department of Research, Institute of Liver and Biliary Sciences, Delhi 110070, India
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118
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Identification of novel DNA-damage tolerance genes reveals regulation of translesion DNA synthesis by nucleophosmin. Nat Commun 2014; 5:5437. [PMID: 25421715 PMCID: PMC4263322 DOI: 10.1038/ncomms6437] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Accepted: 10/01/2014] [Indexed: 01/13/2023] Open
Abstract
Cells cope with replication-blocking lesions via translesion DNA synthesis (TLS). TLS is carried out by low-fidelity DNA polymerases that replicate across lesions, thereby preventing genome instability at the cost of increased point mutations. Here we perform a two-stage siRNA-based functional screen for mammalian TLS genes and identify 17 validated TLS genes. One of the genes, NPM1, is frequently mutated in acute myeloid leukaemia (AML). We show that NPM1 (nucleophosmin) regulates TLS via interaction with the catalytic core of DNA polymerase-η (polη), and that NPM1 deficiency causes a TLS defect due to proteasomal degradation of polη. Moreover, the prevalent NPM1c+ mutation that causes NPM1 mislocalization in ~30% of AML patients results in excessive degradation of polη. These results establish the role of NPM1 as a key TLS regulator, and suggest a mechanism for the better prognosis of AML patients carrying mutations in NPM1. Cells cope with replication-blocking DNA lesions by translesion DNA synthesis (TLS) polymerases, including polη. Here, the authors show that NPM1, a gene frequently mutated in acute myeloid leukaemia, protects polη from proteasomal degradation, and that NPM1 deficiency causes a TLS defect.
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119
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Woods SJ, Hannan KM, Pearson RB, Hannan RD. The nucleolus as a fundamental regulator of the p53 response and a new target for cancer therapy. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2014; 1849:821-9. [PMID: 25464032 DOI: 10.1016/j.bbagrm.2014.10.007] [Citation(s) in RCA: 98] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2014] [Revised: 10/30/2014] [Accepted: 10/31/2014] [Indexed: 01/10/2023]
Abstract
BACKGROUND Recent studies have highlighted the fundamental role that key oncogenes such as MYC, RAS and PI3K occupy in driving RNA Polymerase I transcription in the nucleolus. In addition to maintaining essential levels of protein synthesis, hyperactivated ribosome biogenesis and nucleolar function plays a central role in suppressing p53 activation in response to oncogenic stress. Consequently, disruption of ribosome biogenesis by agents such as the small molecule inhibitor of RNA Polymerase I transcription, CX-5461, has shown unexpected, potent, and selective effects in killing tumour cells via disruption of nucleolar function leading to activation of p53, independent of DNA damage. SCOPE OF REVIEW This review will explore the mechanism of DNA damage-independent activation of p53 via the nucleolar surveillance pathway and how this can be utilised to design novel cancer therapies. MAJOR CONCLUSION AND GENERAL SIGNIFICANCE Non-genotoxic targeting of nucleolar function may provide a new paradigm for treatment of a broad range of oncogene-driven malignancies with improved therapeutic windows. This article is part of a Special Issue entitled: Translation and Cancer.
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Affiliation(s)
- Simone J Woods
- Division of Research, Peter MacCallum Cancer Centre, East Melbourne, Victoria 3002, Australia
| | - Katherine M Hannan
- Division of Research, Peter MacCallum Cancer Centre, East Melbourne, Victoria 3002, Australia; Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, Victoria 3052, Australia
| | - Richard B Pearson
- Division of Research, Peter MacCallum Cancer Centre, East Melbourne, Victoria 3002, Australia; Sir Peter MacCallum Department of Oncology, University of Melbourne, Parkville, Victoria 3052, Australia; Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, Victoria 3052, Australia; Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3168, Australia.
| | - Ross D Hannan
- Division of Research, Peter MacCallum Cancer Centre, East Melbourne, Victoria 3002, Australia; Sir Peter MacCallum Department of Oncology, University of Melbourne, Parkville, Victoria 3052, Australia; Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, Victoria 3052, Australia; Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3168, Australia; School of Biomedical Sciences, University of Queensland, Queensland 4072, Australia.
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120
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Holmberg Olausson K, Nistér M, Lindström MS. Loss of nucleolar histone chaperone NPM1 triggers rearrangement of heterochromatin and synergizes with a deficiency in DNA methyltransferase DNMT3A to drive ribosomal DNA transcription. J Biol Chem 2014; 289:34601-19. [PMID: 25349213 DOI: 10.1074/jbc.m114.569244] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Nucleoli are prominent nuclear structures assembled and organized around actively transcribed ribosomal DNA (rDNA). The nucleolus has emerged as a platform for the organization of chromatin enriched for repressive histone modifications associated with repetitive DNA. NPM1 is a nucleolar protein required for the maintenance of genome stability. However, the role of NPM1 in nucleolar chromatin dynamics and ribosome biogenesis remains unclear. We found that normal fibroblasts and cancer cells depleted of NPM1 displayed deformed nucleoli and a striking rearrangement of perinucleolar heterochromatin, as identified by immunofluorescence staining of trimethylated H3K9, trimethylated H3K27, and heterochromatin protein 1γ (HP1γ/CBX3). By co-immunoprecipitation we found NPM1 associated with HP1γ and core and linker histones. Moreover, NPM1 was required for efficient tethering of HP1γ-enriched chromatin to the nucleolus. We next tested whether the alterations in perinucleolar heterochromatin architecture correlated with a difference in the regulation of rDNA. U1242MG glioma cells depleted of NPM1 presented with altered silver staining of nucleolar organizer regions, coupled to a modest decrease in H3K9 di- and trimethylation at the rDNA promoter. rDNA transcription and cell proliferation were sustained in these cells, indicating that altered organization of heterochromatin was not secondary to inhibition of rDNA transcription. Furthermore, knockdown of DNA methyltransferase DNMT3A markedly enhanced rDNA transcription in NPM1-depleted U1242MG cells. In summary, this study highlights a function of NPM1 in the spatial organization of nucleolus-associated heterochromatin.
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Affiliation(s)
- Karl Holmberg Olausson
- From the Department of Oncology-Pathology, Karolinska Institutet, Cancer Center Karolinska, Karolinska University Hospital, SE-17176 Stockholm, Sweden
| | - Monica Nistér
- From the Department of Oncology-Pathology, Karolinska Institutet, Cancer Center Karolinska, Karolinska University Hospital, SE-17176 Stockholm, Sweden
| | - Mikael S Lindström
- From the Department of Oncology-Pathology, Karolinska Institutet, Cancer Center Karolinska, Karolinska University Hospital, SE-17176 Stockholm, Sweden
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Peltonen K, Colis L, Liu H, Jäämaa S, Zhang Z, Af Hällström T, Moore HM, Sirajuddin P, Laiho M. Small molecule BMH-compounds that inhibit RNA polymerase I and cause nucleolar stress. Mol Cancer Ther 2014; 13:2537-46. [PMID: 25277384 DOI: 10.1158/1535-7163.mct-14-0256] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Activation of the p53 pathway has been considered a therapeutic strategy to target cancers. We have previously identified several p53-activating small molecules in a cell-based screen. Two of the compounds activated p53 by causing DNA damage, but this modality was absent in the other four. We recently showed that one of these, BMH-21, inhibits RNA polymerase I (Pol I) transcription, causes the degradation of Pol I catalytic subunit RPA194, and has potent anticancer activity. We show here that three remaining compounds in this screen, BMH-9, BMH-22, and BMH-23, cause reorganization of nucleolar marker proteins consistent with segregation of the nucleolus, a hallmark of Pol I transcription stress. Further, the compounds destabilize RPA194 in a proteasome-dependent manner and inhibit nascent rRNA synthesis and expression of the 45S rRNA precursor. BMH-9- and BMH-22-mediated nucleolar stress was detected in ex vivo-cultured human prostate tissues indicating good tissue bioactivity. Testing of closely related analogues showed that their activities were chemically constrained. Viability screen for BMH-9, BMH-22, and BMH-23 in the NCI60 cancer cell lines showed potent anticancer activity across many tumor types. Finally, we show that the Pol I transcription stress by BMH-9, BMH-22, and BMH-23 is independent of p53 function. These results highlight the dominant impact of Pol I transcription stress on p53 pathway activation and bring forward chemically novel lead molecules for Pol I inhibition, and, potentially, cancer targeting.
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Affiliation(s)
- Karita Peltonen
- Center for Drug Research, University of Helsinki, Helsinki, Finland
| | - Laureen Colis
- Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Hester Liu
- Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Sari Jäämaa
- Center for Drug Research, University of Helsinki, Helsinki, Finland
| | - Zhewei Zhang
- Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Taija Af Hällström
- Institute for Molecular Medicine Finland FIMM, University of Helsinki, Helsinki, Finland
| | - Henna M Moore
- Center for Drug Research, University of Helsinki, Helsinki, Finland
| | - Paul Sirajuddin
- Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Marikki Laiho
- Center for Drug Research, University of Helsinki, Helsinki, Finland. Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland. Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, Maryland.
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122
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Hamilton G, Abraham AG, Morton J, Sampson O, Pefani DE, Khoronenkova S, Grawenda A, Papaspyropoulos A, Jamieson N, McKay C, Sansom O, Dianov GL, O'Neill E. AKT regulates NPM dependent ARF localization and p53mut stability in tumors. Oncotarget 2014; 5:6142-67. [PMID: 25071014 PMCID: PMC4171619 DOI: 10.18632/oncotarget.2178] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2014] [Accepted: 07/07/2014] [Indexed: 12/31/2022] Open
Abstract
Nucleophosmin (NPM) is known to regulate ARF subcellular localization and MDM2 activity in response to oncogenic stress, though the precise mechanism has remained elusive. Here we describe how NPM and ARF associate in the nucleoplasm to form a MDM2 inhibitory complex. We find that oligomerization of NPM drives nucleolar accumulation of ARF. Moreover, the formation of NPM and ARF oligomers antagonizes MDM2 association with the inhibitory complex, leading to activation of MDM2 E3-ligase activity and targeting of p53. We find that AKT phosphorylation of NPM-Ser48 prevents oligomerization that results in nucleoplasmic localization of ARF, constitutive MDM2 inhibition and stabilization of p53. We also show that ARF promotes p53 mutant stability in tumors and suppresses p73 mediated p21 expression and senescence. We demonstrate that AKT and PI3K inhibitors may be effective in treatment of therapeutically resistant tumors with elevated AKT and carrying gain of function mutations in p53. Our results show that the clinical candidate AKT inhibitor MK-2206 promotes ARF nucleolar localization, reduced p53(mut) stability and increased sensitivity to ionizing radiation in a xenograft model of pancreatic cancer. Analysis of human tumors indicates that phospho-S48-NPM may be a useful biomarker for monitoring AKT activity and in vivo efficacy of AKT inhibitor treatment. Critically, we propose that combination therapy involving PI3K-AKT inhibitors would benefit from a patient stratification rationale based on ARF and p53(mut) status.
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Affiliation(s)
- Garth Hamilton
- Cancer Research UK/MRC Oxford Institute, Department of Oncology, University of Oxford, Old Road Campus, Roosevelt Drive, UK; These authors contributed equally to this work
| | - Aswin G Abraham
- Cancer Research UK/MRC Oxford Institute, Department of Oncology, University of Oxford, Old Road Campus, Roosevelt Drive, UK; These authors contributed equally to this work
| | - Jennifer Morton
- Beatson Institute for Cancer Research, Garscube Estate, Switchback Road, Glasgow, UK
| | - Oliver Sampson
- Cancer Research UK/MRC Oxford Institute, Department of Oncology, University of Oxford, Old Road Campus, Roosevelt Drive, UK
| | - Dafni E Pefani
- Cancer Research UK/MRC Oxford Institute, Department of Oncology, University of Oxford, Old Road Campus, Roosevelt Drive, UK
| | - Svetlana Khoronenkova
- Cancer Research UK/MRC Oxford Institute, Department of Oncology, University of Oxford, Old Road Campus, Roosevelt Drive, UK
| | - Anna Grawenda
- Cancer Research UK/MRC Oxford Institute, Department of Oncology, University of Oxford, Old Road Campus, Roosevelt Drive, UK
| | - Angelos Papaspyropoulos
- Cancer Research UK/MRC Oxford Institute, Department of Oncology, University of Oxford, Old Road Campus, Roosevelt Drive, UK
| | - Nigel Jamieson
- West of Scotland Pancreatic Unit and University Department of Surgery, Glasgow Royal Infirmary, Alexandra Parade. Glasgow
| | - Colin McKay
- West of Scotland Pancreatic Unit and University Department of Surgery, Glasgow Royal Infirmary, Alexandra Parade. Glasgow
| | - Owen Sansom
- Beatson Institute for Cancer Research, Garscube Estate, Switchback Road, Glasgow, UK
| | - Grigory L Dianov
- Cancer Research UK/MRC Oxford Institute, Department of Oncology, University of Oxford, Old Road Campus, Roosevelt Drive, UK
| | - Eric O'Neill
- Cancer Research UK/MRC Oxford Institute, Department of Oncology, University of Oxford, Old Road Campus, Roosevelt Drive, UK
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Physical and functional interaction of the TPL2 kinase with nucleophosmin. Oncogene 2014; 34:2516-26. [PMID: 24998852 DOI: 10.1038/onc.2014.183] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2013] [Revised: 05/01/2014] [Accepted: 05/21/2014] [Indexed: 12/18/2022]
Abstract
Tumor Progression Locus 2 (TPL2) is widely recognized as a cytoplasmic mitogen-activated protein 3 kinase with a prominent role in the regulation of inflammatory and oncogenic signal transduction. Herein we report that TPL2 may also operate in the nucleus as a physical and functional partner of nucleophosmin (NPM/B23), a major nucleolar phosphoprotein with diverse cellular activities linked to malignancy. We demonstrate that TPL2 mediates the phosphorylation of a fraction of NPM at threonine 199, an event required for its proteasomal degradation and maintenance of steady-state NPM levels. Upon exposure to ultraviolet C, Tpl2 is required for the translocation of de-phosphorylated NPM from the nucleolus to the nucleoplasm. NPM is an endogenous inhibitor of HDM2:p53 interaction and knockdown of TPL2 was found to result in reduced binding of NPM to HDM2, with concomitant defects in p53 accumulation following genotoxic or ribosomal stress. These findings expand our understanding of the function of TPL2 as a negative regulator of carcinogenesis by defining a nuclear role for this kinase in the topological sequestration of NPM, linking p53 signaling to the generation of threonine 199-phosphorylated NPM.
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The nucleolus—guardian of cellular homeostasis and genome integrity. Chromosoma 2014; 122:487-97. [PMID: 24022641 DOI: 10.1007/s00412-013-0430-0] [Citation(s) in RCA: 144] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2013] [Accepted: 08/05/2013] [Indexed: 01/25/2023]
Abstract
All organisms sense and respond to conditions that stress their homeostasis by downregulating the synthesis of rRNA and ribosome biogenesis, thus designating the nucleolus as the central hub in coordinating the cellular stress response. One of the most intriguing roles of the nucleolus, long regarded as a mere ribosome-producing factory, is its participation in monitoring cellular stress signals and transmitting them to the RNA polymerase I (Pol I) transcription machinery. As rRNA synthesis is a most energy-consuming process, switching off transcription of rRNA genes is an effective way of saving the energy required to maintain cellular homeostasis during acute stress. The Pol I transcription machinery is the key convergence point that collects and integrates a vast array of information from cellular signaling cascades to regulate ribosome production which, in turn, guides cell growth and proliferation. This review focuses on the mechanisms that link cell physiology to rDNA silencing, a prerequisite for nucleolar integrity and cell survival.
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Downregulation of rRNA transcription triggers cell differentiation. PLoS One 2014; 9:e98586. [PMID: 24879416 PMCID: PMC4039485 DOI: 10.1371/journal.pone.0098586] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2013] [Accepted: 05/05/2014] [Indexed: 11/19/2022] Open
Abstract
Responding to various stimuli is indispensable for the maintenance of homeostasis. The downregulation of ribosomal RNA (rRNA) transcription is one of the mechanisms involved in the response to stimuli by various cellular processes, such as cell cycle arrest and apoptosis. Cell differentiation is caused by intra- and extracellular stimuli and is associated with the downregulation of rRNA transcription as well as reduced cell growth. The downregulation of rRNA transcription during differentiation is considered to contribute to reduced cell growth. However, the downregulation of rRNA transcription can induce various cellular processes; therefore, it may positively regulate cell differentiation. To test this possibility, we specifically downregulated rRNA transcription using actinomycin D or a siRNA for Pol I-specific transcription factor IA (TIF-IA) in HL-60 and THP-1 cells, both of which have differentiation potential. The inhibition of rRNA transcription induced cell differentiation in both cell lines, which was demonstrated by the expression of the common differentiation marker CD11b. Furthermore, TIF-IA knockdown in an ex vivo culture of mouse hematopoietic stem cells increased the percentage of myeloid cells and reduced the percentage of immature cells. We also evaluated whether differentiation was induced via the inhibition of cell cycle progression because rRNA transcription is tightly coupled to cell growth. We found that cell cycle arrest without affecting rRNA transcription did not induce differentiation. To the best of our knowledge, our results demonstrate the first time that the downregulation of rRNA levels could be a trigger for the induction of differentiation in mammalian cells. Furthermore, this phenomenon was not simply a reflection of cell cycle arrest. Our results provide a novel insight into the relationship between rRNA transcription and cell differentiation.
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126
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Martinelli C, Colombo E, Piccini D, Sironi C, Pelicci PG, de Marco A. An intrabody specific for the nucleophosmin carboxy-terminal mutant and fused to a nuclear localization sequence binds its antigen but fails to relocate it in the nucleus. ACTA ACUST UNITED AC 2014. [PMID: 28626645 PMCID: PMC5466097 DOI: 10.1016/j.btre.2014.05.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A scFv intrabody specific for the NPMc+ mutant NES sequence was isolated. It was expressed as a fusion with a NLS and such construct accumulates in the nucleus. The scFv-NLS fusion binds its antigen in the cytoplasm of eukaryotic cells. The complex shuttles to the nucleus but accumulates in the cytoplasm. Stronger NLS should be developed to revert the strength of pathogenic NES.
The cytoplasmic accumulation of NPM1 (NPMc+) is found in acute myeloid leukemia (AML) with NPM1 mutation. NPM1 must shuttle between nucleus and cytoplasm to assure physiological protein synthesis and, therefore, the elimination of NPMc+ is not a suitable therapeutic option. We isolated, characterized, and produced a functional scFv intrabody fused to nuclear localization signal(s) (NLS) that does not recognize NPM1 but binds to the mutant-specific C-terminal NES (nuclear export signal) of NPMc+, responsible for its cytoplasmic accumulation. The scFv-NLS fusion accumulated in the nuclei of wild type cells and strongly bound to its antigen in the cytoplasm of NPMc+ expressing cells. However, it failed to relocate the majority of NPMc+ in the nucleus, even when fused to four NLS. Our results show the technical feasibility of producing recombinant intrabodies with defined sub-cellular targeting and nuclear accumulation but the lack of information concerning the features that confer variable strength to the signal peptides impairs the development of biomolecules able to counteract pathological sub-cellular distribution of shuttling proteins.
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Affiliation(s)
| | - Emanuela Colombo
- Department of Experimental Oncology, IEO, Via Adamello 16, 20139 Milan, Italy.,Department of Health Sciences, University of Milan, 20133 Milan, Italy
| | | | - Cristina Sironi
- Department of Experimental Oncology, IEO, Via Adamello 16, 20139 Milan, Italy
| | - Pier Giuseppe Pelicci
- Department of Experimental Oncology, IEO, Via Adamello 16, 20139 Milan, Italy.,Department of Health Sciences, University of Milan, 20133 Milan, Italy
| | - Ario de Marco
- Department of Biomedical Sciences and Engineering, University of Nova Gorica, Glavni Trg 9, SI-5261 Vipava, Slovenia
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127
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Shaiken TE, Opekun AR. Dissecting the cell to nucleus, perinucleus and cytosol. Sci Rep 2014; 4:4923. [PMID: 24815916 PMCID: PMC4017230 DOI: 10.1038/srep04923] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Accepted: 04/22/2014] [Indexed: 12/25/2022] Open
Abstract
Cells have been described under the microscope as organelles containing cytoplasm and the nucleus. However, an unnoted structure exists between the cytoplasm and the nucleoplasm of eukaryotic cells. In addition to the nuclear envelope, there exists a perinuclear region (PNR or perinucleus) with unknown composition and function. Until now, an investigation of the role of the perinucleus has been restricted by the absence of a PNR isolation method. This manuscript describes a perinucleus isolation technique on the basis of its unique compact organization. The perinucleus was found to contain approximately 15 to 18% of the total proteins of the mammalian cell, almost half of the proteins of nuclei. Using four different normal and cancer cell lines, it was shown that the composition of PNR is highly dynamic. Application of the method showed that translocation of the p53 tumor-suppressor protein to the perinucleus in immortalized MEF cells is correlated with the translocation of p53-stabilizing protein, nucleophosmin (B23), to the PNR. Herein, the concept of the perinuclear region is advanced as a formal, identifiable structure. The roles of the perinucleus in maintaining genome integrity, regulation of gene expression and understanding of malignant transformation are discussed.
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Affiliation(s)
- Tattym E Shaiken
- Department of Molecular and Cellular Oncology, University of Texas M. D. Anderson Cancer Center, Houston, TX 77030, USA
| | - Antone R Opekun
- Departments of Medicine & Pediatrics G.I. & S.A.H.S. Baylor College of Medicine-McNair Faculty Center A10.019 One Baylor Plaza (GI Medicine MS901), Houston, Texas 77030, USA
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128
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Ren Z, Aerts JL, Pen JJ, Heirman C, Breckpot K, De Grève J. Phosphorylated STAT3 physically interacts with NPM and transcriptionally enhances its expression in cancer. Oncogene 2014; 34:1650-7. [PMID: 24793791 DOI: 10.1038/onc.2014.109] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2013] [Revised: 03/04/2014] [Accepted: 03/17/2014] [Indexed: 12/15/2022]
Abstract
The signal transducer and activator of transcription 3 (STAT3) can be activated by the tyrosine kinase domain of the chimeric protein nucleophosmin/anaplastic lymphoma kinase (NPM/ALK), and has a pivotal role in mediating NPM/ALK-related malignant cell transformation. Although the role of STAT3 and wild-type NPM in oncogenesis has been extensively investigated, the relationship between both molecules in cancer remains poorly understood. In the present study, we first demonstrate that STAT3 phosphorylation at tyrosine 705 is accompanied by a concomitant increase in the expression level of NPM. Nuclear co-translocation of phosphorylated STAT3 with NPM can be triggered by interferon-alpha (IFN-α) stimulation of Jurkat cells and phosphorylated STAT3 co-localizes with NPM in cancer cells showing constitutive STAT3 activation. We further demonstrate that STAT3 phosphorylation can transcriptionally mediate NPM upregulation in IFN-α-stimulated Jurkat cells and is responsible for maintaining its expression in cancer cells showing constitutive STAT3 activation. Inhibition of STAT3 phosphorylation or knockdown of NPM expression abrogates their simultaneous transnuclear movements. Finally, we found evidence for a physical interaction between NPM and STAT3 in conditions of STAT3 activation. In conclusion, NPM is a downstream effector of the STAT3 signaling, and can facilitate the nuclear entry of phosphorylated STAT3. These observations might open novel opportunities for targeting the STAT3 pathway in cancer.
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Affiliation(s)
- Z Ren
- 1] Laboratory of Medical and Molecular Oncology (LMMO), Department of Medical Oncology, UZ Brussel, Vrije Universiteit Brussel, Brussels, Belgium [2] Department of General Surgery, The first People's Hospital of Shanghai, Shanghai Jiaotong University, Shanghai, China [3] Department of Medical Oncology, Oncologisch Centrum of the Universitair Ziekenhuis Brussel, Vrije Universiteit Brussel, Brussels, Belgium
| | - J L Aerts
- Department of Immunology-Physiology, Vrije Universiteit Brussel, Brussels, Belgium
| | - J J Pen
- 1] Department of Medical Oncology, Oncologisch Centrum of the Universitair Ziekenhuis Brussel, Vrije Universiteit Brussel, Brussels, Belgium [2] Department of Immunology-Physiology, Vrije Universiteit Brussel, Brussels, Belgium
| | - C Heirman
- Department of Immunology-Physiology, Vrije Universiteit Brussel, Brussels, Belgium
| | - K Breckpot
- Department of Immunology-Physiology, Vrije Universiteit Brussel, Brussels, Belgium
| | - J De Grève
- 1] Laboratory of Medical and Molecular Oncology (LMMO), Department of Medical Oncology, UZ Brussel, Vrije Universiteit Brussel, Brussels, Belgium [2] Department of Medical Oncology, Oncologisch Centrum of the Universitair Ziekenhuis Brussel, Vrije Universiteit Brussel, Brussels, Belgium
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129
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Poletto M, Lirussi L, Wilson DM, Tell G. Nucleophosmin modulates stability, activity, and nucleolar accumulation of base excision repair proteins. Mol Biol Cell 2014; 25:1641-52. [PMID: 24648491 PMCID: PMC4019495 DOI: 10.1091/mbc.e13-12-0717] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Revised: 02/19/2014] [Accepted: 03/10/2014] [Indexed: 01/25/2023] Open
Abstract
Nucleophosmin (NPM1) is a multifunctional protein that controls cell growth and genome stability via a mechanism that involves nucleolar-cytoplasmic shuttling. It is clear that NPM1 also contributes to the DNA damage response, yet its exact function is poorly understood. We recently linked NPM1 expression to the functional activation of the major abasic endonuclease in mammalian base excision repair (BER), apurinic/apyrimidinic endonuclease 1 (APE1). Here we unveil a novel role for NPM1 as a modulator of the whole BER pathway by 1) controlling BER protein levels, 2) regulating total BER capacity, and 3) modulating the nucleolar localization of several BER enzymes. We find that cell treatment with the genotoxin cisplatin leads to concurrent relocalization of NPM1 and BER components from nucleoli to the nucleoplasm, and cellular experiments targeting APE1 suggest a role for the redistribution of nucleolar BER factors in determining cisplatin toxicity. Finally, based on the use of APE1 as a representative protein of the BER pathway, our data suggest a function for BER proteins in the regulation of ribogenesis.
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Affiliation(s)
- Mattia Poletto
- Department of Medical and Biological Sciences, University of Udine, Udine 33100, Italy
| | - Lisa Lirussi
- Department of Medical and Biological Sciences, University of Udine, Udine 33100, Italy
| | - David M Wilson
- Laboratory of Molecular Gerontology, National Institute on Aging, Intramural Research Program, National Institutes of Health, Baltimore, MD 21224
| | - Gianluca Tell
- Department of Medical and Biological Sciences, University of Udine, Udine 33100, Italy
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130
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Abstract
Long known as the center of ribosome synthesis, the nucleolus is connected to cell cycle regulation in more subtle ways. One is a surveillance system that reacts promptly when rRNA synthesis or processing is impaired, halting cell cycle progression. Conversely, the nucleolus also acts as a first-responder to growth-related stress signals. Here we review emerging concepts on how these "infraribosomal" links between the nucleolus and cell cycle progression operate in both forward and reverse gears. We offer perspectives on how new cancer therapeutic designs that target this infraribosomal mode of cell growth control may shape future clinical progress.
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Affiliation(s)
- Robert Y L Tsai
- Center for Cancer and Stem Cell Biology, Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, Texas, USA; and
| | - Thoru Pederson
- Program in Cell and Developmental Dynamics, Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts, USA
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131
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Golomb L, Volarevic S, Oren M. p53 and ribosome biogenesis stress: the essentials. FEBS Lett 2014; 588:2571-9. [PMID: 24747423 DOI: 10.1016/j.febslet.2014.04.014] [Citation(s) in RCA: 166] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2014] [Revised: 04/04/2014] [Accepted: 04/04/2014] [Indexed: 12/18/2022]
Abstract
Cell proliferation and cell growth are two tightly linked processes, as the proliferation program cannot be executed without proper accumulation of cell mass, otherwise endangering the fate of the two daughter cells. It is therefore not surprising that ribosome biogenesis, a key element in cell growth, is regulated by many cell cycle regulators. This regulation is exerted transcriptionally and post-transcriptionally, in conjunction with numerous intrinsic and extrinsic signals. Those signals eventually converge at the nucleolus, the cellular compartment that is not only responsible for executing the ribosome biogenesis program, but also serves as a regulatory hub, responsible for integrating and transmitting multiple stress signals to the omnipotent cell fate gatekeeper, p53. In this review we discuss when, how and why p53 is activated upon ribosomal biogenesis stress, and how perturbation of this critical regulatory interplay may impact human disease.
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Affiliation(s)
- Lior Golomb
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Sinisa Volarevic
- Department of Molecular Medicine and Biotechnology, School of Medicine, University of Rijeka, Croatia
| | - Moshe Oren
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel.
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132
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Mitrea DM, Grace CR, Buljan M, Yun MK, Pytel NJ, Satumba J, Nourse A, Park CG, Madan Babu M, White SW, Kriwacki RW. Structural polymorphism in the N-terminal oligomerization domain of NPM1. Proc Natl Acad Sci U S A 2014; 111:4466-71. [PMID: 24616519 PMCID: PMC3970533 DOI: 10.1073/pnas.1321007111] [Citation(s) in RCA: 138] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Nucleophosmin (NPM1) is a multifunctional phospho-protein with critical roles in ribosome biogenesis, tumor suppression, and nucleolar stress response. Here we show that the N-terminal oligomerization domain of NPM1 (Npm-N) exhibits structural polymorphism by populating conformational states ranging from a highly ordered, folded pentamer to a highly disordered monomer. The monomer-pentamer equilibrium is modulated by posttranslational modification and protein binding. Phosphorylation drives the equilibrium in favor of monomeric forms, and this effect can be reversed by Npm-N binding to its interaction partners. We have identified a short, arginine-rich linear motif in NPM1 binding partners that mediates Npm-N oligomerization. We propose that the diverse functional repertoire associated with NPM1 is controlled through a regulated unfolding mechanism signaled through posttranslational modifications and intermolecular interactions.
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Affiliation(s)
- Diana M. Mitrea
- Department of Structural Biology, St. Jude Children’s Research Hospital, Memphis, TN 38105
| | - Christy R. Grace
- Department of Structural Biology, St. Jude Children’s Research Hospital, Memphis, TN 38105
| | - Marija Buljan
- Medical Research Council Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom; and
| | - Mi-Kyung Yun
- Department of Structural Biology, St. Jude Children’s Research Hospital, Memphis, TN 38105
| | - Nicholas J. Pytel
- Department of Structural Biology, St. Jude Children’s Research Hospital, Memphis, TN 38105
| | - John Satumba
- Department of Structural Biology, St. Jude Children’s Research Hospital, Memphis, TN 38105
| | - Amanda Nourse
- Department of Structural Biology, St. Jude Children’s Research Hospital, Memphis, TN 38105
| | - Cheon-Gil Park
- Department of Structural Biology, St. Jude Children’s Research Hospital, Memphis, TN 38105
| | - M. Madan Babu
- Medical Research Council Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom; and
| | - Stephen W. White
- Department of Structural Biology, St. Jude Children’s Research Hospital, Memphis, TN 38105
- Department of Microbiology, Immunology and Biochemistry, University of Tennessee Health Science Center, Memphis, TN 38163
| | - Richard W. Kriwacki
- Department of Structural Biology, St. Jude Children’s Research Hospital, Memphis, TN 38105
- Department of Microbiology, Immunology and Biochemistry, University of Tennessee Health Science Center, Memphis, TN 38163
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133
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Dobbelstein M, Moll U. Targeting tumour-supportive cellular machineries in anticancer drug development. Nat Rev Drug Discov 2014; 13:179-96. [DOI: 10.1038/nrd4201] [Citation(s) in RCA: 175] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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134
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Reed SM, Hagen J, Tompkins VS, Thies K, Quelle FW, Quelle DE. Nuclear interactor of ARF and Mdm2 regulates multiple pathways to activate p53. Cell Cycle 2014; 13:1288-98. [PMID: 24621507 DOI: 10.4161/cc.28202] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The p53 tumor suppressor is controlled by an interactive network of factors that stimulate or inhibit its transcriptional activity. Within that network, Mdm2 functions as the major antagonist of p53 by promoting its ubiquitylation and degradation. Conversely, Tip60 activates p53 through direct association on target promoters as well as acetylation of p53 at lysine 120 (K120). This study examines the functional relationship between Mdm2 and Tip60 with a novel p53 regulator, NIAM (nuclear interactor of ARF and Mdm2). Previous work showed NIAM can suppress proliferation and activate p53 independently of ARF, indicating that other factors mediate those activities. Here, we demonstrate that NIAM is a chromatin-associated protein that binds Tip60. NIAM can promote p53 K120 acetylation, although that modification is not required for NIAM to inhibit proliferation or induce p53 transactivation of the p21 promoter. Notably, Tip60 silencing showed it contributes to but is not sufficient for NIAM-mediated p53 activation, suggesting other mechanisms are involved. Indeed, growth-inhibitory forms of NIAM also bind to Mdm2, and increased NIAM expression levels disrupt p53-Mdm2 association, inhibit p53 polyubiquitylation, and prevent Mdm2-mediated inhibition of p53 transcriptional activity. Importantly, loss of NIAM significantly impairs p53 activation. Together, these results show that NIAM activates p53 through multiple mechanisms involving Tip60 association and Mdm2 inhibition. Thus, NIAM regulates 2 critical pathways that control p53 function and are altered in human cancers, implying an important role for NIAM in tumorigenesis.
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Affiliation(s)
- Sara M Reed
- Department of Pharmacology; University of Iowa College of Medicine; Iowa City, IA USA; Medical Scientist Training Program; University of Iowa College of Medicine; Iowa City, IA USA
| | - Jussara Hagen
- Department of Pharmacology; University of Iowa College of Medicine; Iowa City, IA USA
| | - Van S Tompkins
- Department of Pathology; University of Iowa College of Medicine; Iowa City, IA USA
| | - Katie Thies
- Department of Pharmacology; University of Iowa College of Medicine; Iowa City, IA USA
| | - Frederick W Quelle
- Department of Pharmacology; University of Iowa College of Medicine; Iowa City, IA USA
| | - Dawn E Quelle
- Department of Pharmacology; University of Iowa College of Medicine; Iowa City, IA USA; Medical Scientist Training Program; University of Iowa College of Medicine; Iowa City, IA USA; Department of Pathology; University of Iowa College of Medicine; Iowa City, IA USA
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135
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Brd4 and HEXIM1: multiple roles in P-TEFb regulation and cancer. BIOMED RESEARCH INTERNATIONAL 2014; 2014:232870. [PMID: 24592384 PMCID: PMC3925632 DOI: 10.1155/2014/232870] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/06/2013] [Accepted: 12/19/2013] [Indexed: 12/31/2022]
Abstract
Bromodomain-containing protein 4 (Brd4) and hexamethylene bisacetamide (HMBA) inducible protein 1 (HEXIM1) are two opposing regulators of the positive transcription elongation factor b (P-TEFb), which is the master modulator of RNA polymerase II during transcriptional elongation. While Brd4 recruits P-TEFb to promoter-proximal chromatins to activate transcription, HEXIM1 sequesters P-TEFb into an inactive complex containing the 7SK small nuclear RNA. Besides regulating P-TEFb's transcriptional activity, recent evidence demonstrates that both Brd4 and HEXIM1 also play novel roles in cell cycle progression and tumorigenesis. Here we will discuss the current knowledge on Brd4 and HEXIM1 and their implication as novel therapeutic options against cancer.
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136
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Peltonen K, Colis L, Liu H, Trivedi R, Moubarek MS, Moore HM, Bai B, Rudek MA, Bieberich CJ, Laiho M. A targeting modality for destruction of RNA polymerase I that possesses anticancer activity. Cancer Cell 2014; 25:77-90. [PMID: 24434211 PMCID: PMC3930145 DOI: 10.1016/j.ccr.2013.12.009] [Citation(s) in RCA: 206] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Revised: 10/03/2013] [Accepted: 12/16/2013] [Indexed: 01/07/2023]
Abstract
We define the activity and mechanisms of action of a small molecule lead compound for cancer targeting. We show that the compound, BMH-21, has wide and potent antitumorigenic activity across NCI60 cancer cell lines and represses tumor growth in vivo. BMH-21 binds GC-rich sequences, which are present at a high frequency in ribosomal DNA genes, and potently and rapidly represses RNA polymerase I (Pol I) transcription. Strikingly, we find that BMH-21 causes proteasome-dependent destruction of RPA194, the large catalytic subunit protein of Pol I holocomplex, and this correlates with cancer cell killing. Our results show that Pol I activity is under proteasome-mediated control, which reveals an unexpected therapeutic opportunity.
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Affiliation(s)
- Karita Peltonen
- Molecular Cancer Biology Program and Centre for Drug Research, University of Helsinki, Helsinki 00014, Finland
| | - Laureen Colis
- Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21231, USA
| | - Hester Liu
- Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21231, USA
| | - Rishi Trivedi
- Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21231, USA
| | - Michael S Moubarek
- Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, MD 21250, USA
| | - Henna M Moore
- Molecular Cancer Biology Program and Centre for Drug Research, University of Helsinki, Helsinki 00014, Finland
| | - Baoyan Bai
- Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21231, USA
| | - Michelle A Rudek
- Department of Oncology and The Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, MD 21231, USA
| | - Charles J Bieberich
- Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, MD 21250, USA
| | - Marikki Laiho
- Molecular Cancer Biology Program and Centre for Drug Research, University of Helsinki, Helsinki 00014, Finland; Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21231, USA; Department of Oncology and The Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, MD 21231, USA.
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137
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Quin JE, Devlin JR, Cameron D, Hannan KM, Pearson RB, Hannan RD. Targeting the nucleolus for cancer intervention. Biochim Biophys Acta Mol Basis Dis 2014; 1842:802-16. [PMID: 24389329 DOI: 10.1016/j.bbadis.2013.12.009] [Citation(s) in RCA: 170] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2013] [Accepted: 12/17/2013] [Indexed: 12/17/2022]
Abstract
The contribution of the nucleolus to cancer is well established with respect to its traditional role in facilitating ribosome biogenesis and proliferative capacity. More contemporary studies however, infer that nucleoli contribute a much broader role in malignant transformation. Specifically, extra-ribosomal functions of the nucleolus position it as a central integrator of cellular proliferation and stress signaling, and are emerging as important mechanisms for modulating how oncogenes and tumor suppressors operate in normal and malignant cells. The dependence of certain tumor cells to co-opt nucleolar processes to maintain their cancer phenotypes has now clearly been demonstrated by the application of small molecule inhibitors of RNA Polymerase I to block ribosomal DNA transcription and disrupt nucleolar function (Bywater et al., 2012 [1]). These drugs, which selectively kill tumor cells in vivo while sparing normal cells, have now progressed to clinical trials. It is likely that we have only just begun to scratch the surface of the potential of the nucleolus as a new target for cancer therapy, with "suppression of nucleolar stress" representing an emerging "hallmark" of cancer. This article is part of a Special Issue entitled: Role of the Nucleolus in Human Disease.
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Affiliation(s)
- Jaclyn E Quin
- Oncogenic Signalling and Growth Control Program, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia; Department of Biochemistry and Molecular Biology, The University of Melbourne, Parkville, Victoria, Australia
| | - Jennifer R Devlin
- Oncogenic Signalling and Growth Control Program, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia; Department of Biochemistry and Molecular Biology, The University of Melbourne, Parkville, Victoria, Australia
| | - Donald Cameron
- Oncogenic Signalling and Growth Control Program, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia
| | - Kate M Hannan
- Oncogenic Signalling and Growth Control Program, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia; Department of Biochemistry and Molecular Biology, The University of Melbourne, Parkville, Victoria, Australia
| | - Richard B Pearson
- Oncogenic Signalling and Growth Control Program, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia; Department of Biochemistry and Molecular Biology, The University of Melbourne, Parkville, Victoria, Australia; Sir Peter MacCallum Department of Oncology, The University of Melbourne, Parkville, Victoria, Australia; Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia
| | - Ross D Hannan
- Oncogenic Signalling and Growth Control Program, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia; Department of Biochemistry and Molecular Biology, The University of Melbourne, Parkville, Victoria, Australia; Sir Peter MacCallum Department of Oncology, The University of Melbourne, Parkville, Victoria, Australia; Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia; Department of Pathology, The University of Melbourne, Parkville, Victoria, Australia; School of Biomedical Sciences, The University of Queensland, St Lucia, Queensland, Australia.
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138
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Hock AK, Vousden KH. The role of ubiquitin modification in the regulation of p53. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1843:137-49. [DOI: 10.1016/j.bbamcr.2013.05.022] [Citation(s) in RCA: 121] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Revised: 04/16/2013] [Accepted: 05/23/2013] [Indexed: 01/09/2023]
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139
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Reddy D, Bhattacharya S, Gupta S. Histone Chaperones: Functions beyond Nucleosome Deposition. ACTA ACUST UNITED AC 2014. [DOI: 10.4236/abb.2014.56064] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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140
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Ono W, Hayashi Y, Yokoyama W, Kuroda T, Kishimoto H, Ito I, Kimura K, Akaogi K, Waku T, Yanagisawa J. The nucleolar protein Myb-binding protein 1A (MYBBP1A) enhances p53 tetramerization and acetylation in response to nucleolar disruption. J Biol Chem 2013; 289:4928-40. [PMID: 24375404 DOI: 10.1074/jbc.m113.474049] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Tetramerization of p53 is crucial to exert its biological activity, and nucleolar disruption is sufficient to activate p53. We previously demonstrated that nucleolar stress induces translocation of the nucleolar protein MYBBP1A from the nucleolus to the nucleoplasm and enhances p53 activity. However, whether and how MYBBP1A regulates p53 tetramerization in response to nucleolar stress remain unclear. In this study, we demonstrated that MYBBP1A enhances p53 tetramerization, followed by acetylation under nucleolar stress. We found that MYBBP1A has two regions that directly bind to lysine residues of the p53 C-terminal regulatory domain. MYBBP1A formed a self-assembled complex that provided a molecular platform for p53 tetramerization and enhanced p300-mediated acetylation of the p53 tetramer. Moreover, our results show that MYBBP1A functions to enhance p53 tetramerization that is necessary for p53 activation, followed by cell death with actinomycin D treatment. Thus, we suggest that MYBBP1A plays a pivotal role in the cellular stress response.
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Affiliation(s)
- Wakana Ono
- From the Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba Science City, Ibaraki 305-8577, Japan
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141
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Shamaa S, Laimon N, Aladle DA, Azmy E, Elghannam DM, Salem DA, Taalab MM. Prognostic implications of NPM1 mutations and FLT3 internal tandem duplications in Egyptian patients with cytogenetically normal acute myeloid leukemia. Hematology 2013; 19:22-30. [DOI: 10.1179/1607845413y.0000000085] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Affiliation(s)
- Sameh Shamaa
- Department of Medical OncologyFaculty of Medicine, Mansoura University, Egypt
| | - Nabil Laimon
- Department of Internal MedicineFaculty of Medicine, Mansoura University, Egypt
| | - Doaa A. Aladle
- Department of Clinical PathologyFaculty of Medicine, Mansoura University, Egypt
| | - Emad Azmy
- Department of Clinical HematologyFaculty of Medicine, Mansoura University, Egypt
| | - Doaa M. Elghannam
- Department of Clinical PathologyFaculty of Medicine, Mansoura University, Egypt
| | - Dalia A. Salem
- Department of Clinical PathologyFaculty of Medicine, Mansoura University, Egypt
| | - Mona M. Taalab
- Department of Clinical HematologyFaculty of Medicine, Mansoura University, Egypt
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142
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Tsuda Y, Mori Y, Abe T, Yamashita T, Okamoto T, Ichimura T, Moriishi K, Matsuura Y. Nucleolar Protein B23 Interacts with Japanese Encephalitis Virus Core Protein and Participates in Viral Replication. Microbiol Immunol 2013; 50:225-34. [PMID: 16547420 DOI: 10.1111/j.1348-0421.2006.tb03789.x] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Japanese encephalitis virus (JEV) core protein is detected not only in the cytoplasm but also in the nucleoli of infected cells. We previously showed that a mutant JEV lacking the nucleolar localization of the core protein impaired viral replication in mammalian cells. In this study, we identified a nucleolar phosphoprotein B23 as a protein binding with the core protein of JEV but not with that of dengue virus. The region binding with JEV core protein was mapped to amino acid residues 38 to 77 of B23. Upon JEV infection, some fraction of B23 was translocated from the nucleoli to the cytoplasm, and cytoplasmic B23 was colocalized with the core protein of wild-type JEV but not with that of the mutant JEV. Furthermore, overexpression of dominant negatives of B23 reduced JEV replication. These results suggest that B23 plays an important role in the intracellular localization of the core protein and replication of JEV.
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Affiliation(s)
- Yoshimi Tsuda
- Department of Molecular Virology, Research Institute for Microbial Diseases, Osaka University, Suita, Osaka 565-0871, Japan
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143
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Bursac S, Brdovcak MC, Donati G, Volarevic S. Activation of the tumor suppressor p53 upon impairment of ribosome biogenesis. Biochim Biophys Acta Mol Basis Dis 2013; 1842:817-30. [PMID: 24514102 DOI: 10.1016/j.bbadis.2013.08.014] [Citation(s) in RCA: 114] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Accepted: 08/27/2013] [Indexed: 12/31/2022]
Abstract
Errors in ribosome biogenesis can result in quantitative or qualitative defects in protein synthesis and consequently lead to improper execution of the genetic program and the development of specific diseases. Evidence has accumulated over the last decade suggesting that perturbation of ribosome biogenesis triggers a p53-activating checkpoint signaling pathway, often referred to as the ribosome biogenesis stress checkpoint pathway. Although it was originally suggested that p53 has a prominent role in preventing diseases by monitoring the fidelity of ribosome biogenesis, recent work has demonstrated that p53 activation upon impairment of ribosome biogenesis also mediates pathological manifestations in humans. Perturbations of ribosome biogenesis can trigger a p53-dependent checkpoint signaling pathway independent of DNA damage and the tumor suppressor ARF through inhibitory interactions of specific ribosomal components with the p53 negative regulator, Mdm2. Here we review the recent advances made toward understanding of this newly-recognized checkpoint signaling pathway, its role in health and disease, and discuss possible future directions in this exciting research field. This article is part of a Special Issue entitled: Role of the Nucleolus in Human Disease.
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Affiliation(s)
- Sladana Bursac
- Department of Molecular Medicine and Biotechnology, School of Medicine, University of Rijeka, Braće Branchetta 20, 51000 Rijeka, Croatia
| | - Maja Cokaric Brdovcak
- Department of Molecular Medicine and Biotechnology, School of Medicine, University of Rijeka, Braće Branchetta 20, 51000 Rijeka, Croatia
| | - Giulio Donati
- Catalan Institute of Oncology, Bellvitge Biomedical Research Institute, Institut d'Investigacio' Biome'dica de Bellvitge (IDIBELL), 08908 Hospitalet de Llobregat, Barcelona, Spain
| | - Sinisa Volarevic
- Department of Molecular Medicine and Biotechnology, School of Medicine, University of Rijeka, Braće Branchetta 20, 51000 Rijeka, Croatia.
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144
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Burger K, Mühl B, Kellner M, Rohrmoser M, Gruber-Eber A, Windhager L, Friedel CC, Dölken L, Eick D. 4-thiouridine inhibits rRNA synthesis and causes a nucleolar stress response. RNA Biol 2013; 10:1623-30. [PMID: 24025460 DOI: 10.4161/rna.26214] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
High concentrations (> 100 µM) of the ribonucleoside analog 4-thiouridine (4sU) is widely used in methods for RNA analysis like photoactivatable-ribonucleoside-enhanced crosslinking and immunoprecipitation (PAR-CLIP) and nascent messenger (m)RNA labeling (4sU-tagging). Here, we show that 4sU-tagging at low concentrations ≤ 10 µM can be used to measure production and processing of ribosomal (r)RNA. However, elevated concentrations of 4sU (> 50 µM), which are usually used for mRNA labeling experiments, inhibit production and processing of 47S rRNA. The inhibition of rRNA synthesis is accompanied by nucleoplasmic translocation of nucleolar nucleophosmin (NPM1), induction of the tumor suppressor p53, and inhibition of proliferation. We conclude that metabolic labeling of RNA by 4sU triggers a nucleolar stress response, which might influence the interpretation of results. Therefore, functional ribosome biogenesis, nucleolar integrity, and cell cycle should be addressed in 4sU labeling experiments.
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Affiliation(s)
- Kaspar Burger
- Department of Molecular Epigenetics; Helmholtz Center Munich; Center for Integrated Protein Science Munich (CIPSM); Munich, Germany
| | - Bastian Mühl
- Department of Molecular Epigenetics; Helmholtz Center Munich; Center for Integrated Protein Science Munich (CIPSM); Munich, Germany
| | - Markus Kellner
- Department of Molecular Epigenetics; Helmholtz Center Munich; Center for Integrated Protein Science Munich (CIPSM); Munich, Germany
| | - Michaela Rohrmoser
- Department of Molecular Epigenetics; Helmholtz Center Munich; Center for Integrated Protein Science Munich (CIPSM); Munich, Germany
| | - Anita Gruber-Eber
- Department of Molecular Epigenetics; Helmholtz Center Munich; Center for Integrated Protein Science Munich (CIPSM); Munich, Germany
| | - Lukas Windhager
- Institute for Informatics, Teaching and Research Unit Bioinformatics; Ludwig-Maximilians-University Munich; Munich, Germany
| | - Caroline C Friedel
- Institute for Informatics, Teaching and Research Unit Bioinformatics; Ludwig-Maximilians-University Munich; Munich, Germany
| | - Lars Dölken
- Department of Medicine; Addenbrooke's Hospital; University of Cambridge; Cambridge, UK
| | - Dirk Eick
- Department of Molecular Epigenetics; Helmholtz Center Munich; Center for Integrated Protein Science Munich (CIPSM); Munich, Germany
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145
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Lew QJ, Chu KL, Chia YL, Cheong N, Chao SH. HEXIM1, a New Player in the p53 Pathway. Cancers (Basel) 2013; 5:838-56. [PMID: 24202322 PMCID: PMC3795367 DOI: 10.3390/cancers5030838] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2013] [Revised: 06/24/2013] [Accepted: 06/24/2013] [Indexed: 01/10/2023] Open
Abstract
Hexamethylene bisacetamide-inducible protein 1 (HEXIM1) is best known as the inhibitor of positive transcription elongation factor b (P-TEFb), which controls transcription elongation of RNA polymerase II and Tat transactivation of human immunodeficiency virus. Besides P-TEFb, several proteins have been identified as HEXIM1 binding proteins. It is noteworthy that more than half of the HEXIM1 binding partners are involved in cancers. P53 and two key regulators of the p53 pathway, nucleophosmin (NPM) and human double minute-2 protein (HDM2), are among the factors identified. This review will focus on the functional importance of the interactions between HEXIM1 and p53/NPM/HDM2. NPM and the cytoplasmic mutant of NPM, NPMc+, were found to regulate P-TEFb activity and RNA polymerase II transcription through the interaction with HEXIM1. Importantly, more than one-third of acute myeloid leukemia (AML) patients carry NPMc+, suggesting the involvement of HEXIM1 in tumorigenesis of AML. HDM2 was found to ubiquitinate HEXIM1. The HDM2-mediated ubiquitination of HEXIM1 did not lead to protein degradation of HEXIM1 but enhanced its inhibitory activity on P-TEFb. Recently, HEXIM1 was identified as a novel positive regulator of p53. HEXIM1 prevented p53 ubiquitination by competing with HDM2 in binding to p53. Taken together, the new evidence suggests a role of HEXIM1 in regulating the p53 pathway and tumorigenesis.
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Affiliation(s)
- Qiao Jing Lew
- Expression Engineering Group, Bioprocessing Technology Institute, A*STAR (Agency for Science, Technology and Research), 20 Biopolis Way, #06-01, Singapore 138668, Singapore.
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146
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Ishigami T, Abe K, Aoki I, Minegishi S, Ryo A, Matsunaga S, Matsuoka K, Takeda H, Sawasaki T, Umemura S, Endo Y. Anti‐interleukin‐5 and multiple autoantibodies are associated with human atherosclerotic diseases and serum interleukin‐5 levels. FASEB J 2013; 27:3437-45. [DOI: 10.1096/fj.12-222653] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Tomoaki Ishigami
- Department of Medical Science and Cardiorenal MedicineYokohama City University Graduate School of MedicineYokohamaJapan
| | - Kaito Abe
- Department of Medical Science and Cardiorenal MedicineYokohama City University Graduate School of MedicineYokohamaJapan
| | - Ichiro Aoki
- Department of Molecular PathologyYokohama City University Graduate School of MedicineYokohamaJapan
| | - Shintaro Minegishi
- Department of Medical Science and Cardiorenal MedicineYokohama City University Graduate School of MedicineYokohamaJapan
| | - Akihide Ryo
- Department of MicrobiologyYokohama City University Graduate School of MedicineYokohamaJapan
| | - Satoko Matsunaga
- Department of MicrobiologyYokohama City University Graduate School of MedicineYokohamaJapan
| | - Kazuhiro Matsuoka
- Ehime University Cell‐Free Science and Technology Research Center Division of Proteomedical Sciences; EhimeJapan
| | - Hiroyuki Takeda
- Ehime University Cell‐Free Science and Technology Research Center Division of Proteomedical Sciences; EhimeJapan
| | - Tatsuya Sawasaki
- Ehime University Cell‐Free Science and Technology Research Center Division of Proteomedical Sciences; EhimeJapan
| | - Satoshi Umemura
- Department of Medical Science and Cardiorenal MedicineYokohama City University Graduate School of MedicineYokohamaJapan
| | - Yaeta Endo
- Ehime University Cell‐Free Science and Technology Research Center Division of Proteomedical Sciences; EhimeJapan
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147
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Kojima K, Kornblau SM, Ruvolo V, Dilip A, Duvvuri S, Davis RE, Zhang M, Wang Z, Coombes KR, Zhang N, Qiu YH, Burks JK, Kantarjian H, Shacham S, Kauffman M, Andreeff M. Prognostic impact and targeting of CRM1 in acute myeloid leukemia. Blood 2013; 121:4166-74. [PMID: 23564911 PMCID: PMC3656451 DOI: 10.1182/blood-2012-08-447581] [Citation(s) in RCA: 164] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2012] [Accepted: 03/28/2013] [Indexed: 11/20/2022] Open
Abstract
Chromosomal region maintenance 1 (CRM1) is a nuclear export receptor recognizing proteins bearing a leucine-rich nuclear export signal. CRM1 is involved in nuclear export of tumor suppressors such as p53. We investigated the prognostic significance of CRM1 in acute myeloid leukemia (AML) and effects of a novel small-molecule selective inhibitor of CRM1. CRM1 protein expression was determined in 511 newly diagnosed AML patients and was correlated with mouse double minute 2 (MDM2) and p53 levels. High CRM1 expression was associated with short survival of patients and remained an adverse prognostic factor in multivariate analysis. CRM1 inhibitor KPT-185 induced mainly full-length p53 and apoptosis in a p53-dependent manner, whereas inhibition of proliferation was p53 independent. Patient samples with p53 mutations showed low sensitivity to KPT-185. Nuclear retention of p53 induced by CRM1 inhibition synergized with increased levels of p53 induced by MDM2 inhibition in apoptosis induction. KPT-185 and Nutlin-3a, alone and in combination, induced synergistic apoptosis in patient-derived CD34(+)/CD38(-) AML, but not in normal progenitor cells. Data suggest that CRM1 exerts an antiapoptotic function and is highly prognostic in AML. We propose a novel combinatorial approach for the therapy of AML, aimed at maximal activation of p53-mediated apoptosis by concomitant MDM2 and CRM1 inhibition.
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MESH Headings
- Acrylates/therapeutic use
- Antineoplastic Agents/therapeutic use
- Biomarkers, Tumor/genetics
- Biomarkers, Tumor/physiology
- Cells, Cultured
- Drug Evaluation, Preclinical
- Drug Resistance, Neoplasm/genetics
- Female
- HL-60 Cells
- Humans
- Karyopherins/antagonists & inhibitors
- Karyopherins/genetics
- Karyopherins/physiology
- Leukemia, Myeloid, Acute/diagnosis
- Leukemia, Myeloid, Acute/drug therapy
- Leukemia, Myeloid, Acute/genetics
- Male
- Molecular Targeted Therapy
- Prognosis
- Receptors, Cytoplasmic and Nuclear/antagonists & inhibitors
- Receptors, Cytoplasmic and Nuclear/genetics
- Receptors, Cytoplasmic and Nuclear/physiology
- Triazoles/therapeutic use
- Tumor Suppressor Protein p53/genetics
- Tumor Suppressor Protein p53/metabolism
- Tumor Suppressor Protein p53/physiology
- U937 Cells
- Exportin 1 Protein
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Affiliation(s)
- Kensuke Kojima
- Section of Molecular Hematology and Therapy, Department of Leukemia, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Blvd, Houston, TX 77030, USA.
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148
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Catalano A, O'Day DH. Rad53 homologue forkhead-associated kinase A (FhkA) and Ca2+-binding protein 4a (CBP4a) are nucleolar proteins that differentially redistribute during mitosis in Dictyostelium. Cell Div 2013; 8:4. [PMID: 23587254 PMCID: PMC3637376 DOI: 10.1186/1747-1028-8-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2013] [Accepted: 04/05/2013] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND During mitosis most nucleolar proteins redistribute to other locales providing an opportunity to study the relationship between nucleolar protein localization and function. Dictyostelium is a model organism for the study of several fundamental biological processes and human diseases but only two nucleolar proteins have been studied during mitosis: NumA1 and Snf12. Both of them are linked to the cell cycle. To acquire a better understanding of nucleolar protein localization and dynamics in Dictyostelium we studied the nucleolar localization of two additional proteins during mitosis: Snf12-linked forkhead-associated kinase A (FhkA), which is involved in the cell cycle, and Ca2+-binding protein 4a (CBP4a), which is a binding partner of NumA1. METHODS Polyclonal antibodies were produced in-house. Cells were fixed and probed with either anti-FhkA or anti-CBP4a in order to determine cellular localization during interphase and throughout the stages of mitosis. Colocalization with DAPI nuclear stain allowed us to determine the location of the nucleus and nucleolus while colocalization with anti-α-tubulin allowed us to determine the cell cycle stage. RESULTS Here we verify two novel nucleolar proteins, Rad53 homologue FhkA which localized around the edge of the nucleolus and CBP4a which was detected throughout the entire nucleolus. Treatment with the Ca2+ chelator BAPTA (5 mM) showed that the nucleolar localization of CBP4a is Ca2+-dependent. In response to actinomycin D (0.05 mg/mL) CBP4a disappeared from the nucleolus while FhkA protruded from the nucleus, eventually pinching off as cytoplasmic circles. FhkA and CBP4a redistributed differently during mitosis. FhkA redistributed throughout the entire cell and at the nuclear envelope region from prometaphase through telophase. In contrast, during prometaphase CBP4a relocated to many large, discrete "CBP4a islands" throughout the nucleoplasm. Two larger "CBP4a islands" were also detected specifically at the metaphase plate region. CONCLUSIONS FhkA and CBP4a represent the sixth and seventh nucleolar proteins that have been verified to date in Dictyostelium and the third and fourth studied during mitosis. The protein-specific distributions of all of these nucleolar proteins during interphase and mitosis provide unique insight into nucleolar protein dynamics in this model organism setting the stage for future work.
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Affiliation(s)
- Andrew Catalano
- Department of Cell and Systems Biology, University of Toronto, 25 Harbord st,, Toronto, ON M5S 3G5, Canada.
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149
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Piganeau M, Ghezraoui H, De Cian A, Guittat L, Tomishima M, Perrouault L, René O, Katibah GE, Zhang L, Holmes MC, Doyon Y, Concordet JP, Giovannangeli C, Jasin M, Brunet E. Cancer translocations in human cells induced by zinc finger and TALE nucleases. Genome Res 2013; 23:1182-93. [PMID: 23568838 PMCID: PMC3698511 DOI: 10.1101/gr.147314.112] [Citation(s) in RCA: 107] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Chromosomal translocations are signatures of numerous cancers and lead to expression of fusion genes that act as oncogenes. The wealth of genomic aberrations found in cancer, however, makes it challenging to assign a specific phenotypic change to a specific aberration. In this study, we set out to use genome editing with zinc finger (ZFN) and transcription activator-like effector (TALEN) nucleases to engineer, de novo, translocation-associated oncogenes at cognate endogenous loci in human cells. Using ZFNs and TALENs designed to cut precisely at relevant translocation breakpoints, we induced cancer-relevant t(11;22)(q24;q12) and t(2;5)(p23;q35) translocations found in Ewing sarcoma and anaplastic large cell lymphoma (ALCL), respectively. We recovered both translocations with high efficiency, resulting in the expression of the EWSR1–FLI1 and NPM1–ALK fusions. Breakpoint junctions recovered after ZFN cleavage in human embryonic stem (ES) cell–derived mesenchymal precursor cells fully recapitulated the genomic characteristics found in tumor cells from Ewing sarcoma patients. This approach with tailored nucleases demonstrates that expression of fusion genes found in cancer cells can be induced from the native promoter, allowing interrogation of both the underlying mechanisms and oncogenic consequences of tumor-related translocations in human cells. With an analogous strategy, the ALCL translocation was reverted in a patient cell line to restore the integrity of the two participating chromosomes, further expanding the repertoire of genomic rearrangements that can be engineered by tailored nucleases.
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Affiliation(s)
- Marion Piganeau
- Museum National d'Histoire Naturelle, CNRS UMR7196, Inserm U565, 75005 Paris, France
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150
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Abstract
Lung cancer is a heterogeneous disease at both clinical and molecular levels, posing conceptual and practical bottlenecks in defining key pathways affecting its initiation and progression. Molecules with a central role in lung carcinogenesis are likely to be targeted by multiple deregulated pathways and may have prognostic, predictive, and/or therapeutic value. Here, we report that Tumor Progression Locus 2 (TPL2), a kinase implicated in the regulation of innate and adaptive immune responses, fulfils a role as a suppressor of lung carcinogenesis and is subject to diverse genetic and epigenetic aberrations in lung cancer patients. We show that allelic imbalance at the TPL2 locus, up-regulation of microRNA-370, which targets TPL2 transcripts, and activated RAS (rat sarcoma) signaling may result in down-regulation of TPL2 expression. Low TPL2 levels correlate with reduced lung cancer patient survival and accelerated onset and multiplicity of urethane-induced lung tumors in mice. Mechanistically, TPL2 was found to antagonize oncogene-induced cell transformation and survival through a pathway involving p53 downstream of cJun N-terminal kinase (JNK) and be required for optimal p53 response to genotoxic stress. These results identify multiple oncogenic pathways leading to TPL2 deregulation and highlight its major tumor-suppressing function in the lung.
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