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Kan Q, Peng Z, Wang K, Deng T, Zhou Z, Wu R, Yao C, Wang R. Vascular restenosis following paclitaxel-coated balloon therapy is attributable to NLRP3 activation and LIN9 upregulation. J Transl Med 2024; 22:871. [PMID: 39334121 PMCID: PMC11430030 DOI: 10.1186/s12967-024-05657-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2024] [Accepted: 09/04/2024] [Indexed: 09/30/2024] Open
Abstract
Lower limb arterial occlusive disease is treated with intraluminal devices, such as paclitaxel (PTX)-coated balloons (PCBs); however, post-procedural restenosis remains a significant challenge. NLRP3 activation is known to play a significant role in atherosclerosis, but its involvement in restenosis following PCB intervention remains to be investigated. We identified that NLRP3 was differentially expressed in lower-limb arterial tissues sourced from healthy controls and patients with arterial occlusive disease. Through cell experiments, we confirmed that PTX is involved in the activation of NLRP3. Subsequently, we demonstrated that NLRP3 activation promotes the proliferation and migration of vascular smooth muscle cell (VSMC), thereby reducing their sensitivity to PTX. NLRP3 activation also stimulates the secretion of the inflammatory cytokine interleukin IL-1β. RNA sequencing of IL-1β-treated VSMC revealed the upregulation of BRD4 and LIN9. Further mechanistic investigations confirmed that IL-1β facilitates BRD4 recruitment, leading to enhanced LIN9 expression. The transcription factor LIN9 binds to the promoter region of the cell-cycle regulator AURKA, thereby promoting its transcription and subsequently upregulating the expression of the cell proliferation-associated molecule FOXM1. These processes ultimately mediate the proliferation, migration, and PTX resistance of VSMC. Additionally, we discovered that JQ1 inhibited the overexpression of the above molecules, and exhibited a synergistic effect with PTX. Our conclusions were validated through in vivo experiments in Sprague-Dawley rats. Collectively, our findings provide insights into the molecular mechanisms underlying restenosis following PCB therapy, and suggest that the combined use of JQ1 and PTX devices may represent a promising therapeutic strategy.
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Affiliation(s)
- Qinghui Kan
- Division of Vascular Surgery, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, 510080, China
- National-Guangdong Joint Engineering Laboratory for Diagnosis and Treatment of Vascular Disease, First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, 510080, China
| | - Zhanli Peng
- Division of Vascular Surgery, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, 510080, China
- National-Guangdong Joint Engineering Laboratory for Diagnosis and Treatment of Vascular Disease, First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, 510080, China
| | - Kangjie Wang
- Division of Vascular Surgery, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, 510080, China
- National-Guangdong Joint Engineering Laboratory for Diagnosis and Treatment of Vascular Disease, First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, 510080, China
| | - Tang Deng
- Division of Vascular Surgery, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, 510080, China
- National-Guangdong Joint Engineering Laboratory for Diagnosis and Treatment of Vascular Disease, First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, 510080, China
| | - Zhihao Zhou
- Division of Vascular Surgery, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, 510080, China
- National-Guangdong Joint Engineering Laboratory for Diagnosis and Treatment of Vascular Disease, First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, 510080, China
| | - Ridong Wu
- Division of Vascular Surgery, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, 510080, China
| | - Chen Yao
- Division of Vascular Surgery, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, 510080, China.
| | - Rui Wang
- Division of Vascular Surgery, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, 510080, China.
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2
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Hou Q, Zhong Y, Liao M, Chen C, Li Y, Li X, Liu J. Upregulation of the tumor suppressor gene LIN9 enhances tumorigenesis and predicts poor prognosis of lung adenocarcinoma. Heliyon 2024; 10:e35012. [PMID: 39157309 PMCID: PMC11328102 DOI: 10.1016/j.heliyon.2024.e35012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2023] [Revised: 07/14/2024] [Accepted: 07/22/2024] [Indexed: 08/20/2024] Open
Abstract
Background LIN9, a gene associated with various cancers, is considered a tumor suppressor. However, the role of LIN9 in lung adenocarcinoma (LUAD) remains unknown. In this study, we aimed to assess the role of LIN9 in the occurrence and prognosis of LUAD. Methods Using three-tier HTSeq count RNA sequencing data from The Cancer Genome Atlas, we assessed LIN9 expression for the LUAD dataset using the DESeq2 R package and RT-qPCR experiments. Biological functions were assessed using gene set enrichment analysis (clusterProfiler and GOplot). The expression of LIN9 and the infiltration of immune cells were assessed by Single-sample gene set enrichment analysis. We conducted correlation study using clinical characteristics and receiver operating characteristic curve analysis. The predictive value of LIN9 was determined using univariate and multivariate Cox regression as well as Kaplan-Meier analysis. Additionally, functional studies were conducted to validate its role in the progression of LUAD. Results Expression of LIN9 was significantly elevated in LUAD, primarily influencing cell cycle, division, and signaling pathways. High LIN9 expression correlated positively with the infiltration of Th2 cells and inversely with that of plasmacytoid dendritic cells. Furthermore, LIN9 was associated with older age and advanced clinical stages, posing risks to overall, progression-free, and disease-specific survival. LIN9 served as a good diagnostic marker, particularly in females, patients aged over 65, and those with clinical N1-3 and M1 stages. Elevated LIN9 expression enhanced proliferation, migration, and invasion of LUAD cells. Conclusion High LIN9 expression potentially contributes to LUAD occurrence through cell cycle regulation and chromosomal modification. It promotes the malignant characteristics of LUAD cells and holds prognostic value for affected patients.
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Affiliation(s)
- Qinghua Hou
- Department of Thoracic Surgery, Peking University Shenzhen Hospital, Shenzhen, Guangdong, 518036, China
| | - Yanfeng Zhong
- Department of Central Laboratory, Peking University Shenzhen Hospital, Shenzhen, Guangdong, 518036, China
| | - Mengying Liao
- Department of Pathology, Peking University Shenzhen Hospital, Shenzhen, Guangdong, 518036, China
| | - Chao Chen
- Department of Thoracic Surgery, Peking University Shenzhen Hospital, Shenzhen, Guangdong, 518036, China
| | - Yanling Li
- Department of Central Laboratory, Peking University Shenzhen Hospital, Shenzhen, Guangdong, 518036, China
| | - Xiaoqing Li
- Department of Thoracic Surgery, Peking University Shenzhen Hospital, Shenzhen, Guangdong, 518036, China
| | - Jixian Liu
- Department of Thoracic Surgery, Peking University Shenzhen Hospital, Shenzhen, Guangdong, 518036, China
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Hoareau M, Rincheval-Arnold A, Gaumer S, Guénal I. DREAM a little dREAM of DRM: Model organisms and conservation of DREAM-like complexes: Model organisms uncover the mechanisms of DREAM-mediated transcription regulation. Bioessays 2024; 46:e2300125. [PMID: 38059789 DOI: 10.1002/bies.202300125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Revised: 11/23/2023] [Accepted: 11/24/2023] [Indexed: 12/08/2023]
Abstract
DREAM complexes are transcriptional regulators that control the expression of hundreds to thousands of target genes involved in the cell cycle, quiescence, differentiation, and apoptosis. These complexes contain many subunits that can vary according to the considered target genes. Depending on their composition and the nature of the partners they recruit, DREAM complexes control gene expression through diverse mechanisms, including chromatin remodeling, transcription cofactor and factor recruitment at various genomic binding sites. This complexity is particularly high in mammals. Since the discovery of the first dREAM complex (drosophila Rb, E2F, and Myb) in Drosophila melanogaster, model organisms such as Caenorhabditis elegans, and plants allowed a deeper understanding of the processes regulated by DREAM-like complexes. Here, we review the conservation of these complexes. We discuss the contribution of model organisms to the study of DREAM-mediated transcriptional regulatory mechanisms and their relevance in characterizing novel activities of DREAM complexes.
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Affiliation(s)
- Marion Hoareau
- Université Paris-Saclay, UVSQ, LGBC, Versailles, France
- Université PSL, EPHE, Paris, France
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4
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Abstract
Perfectly orchestrated periodic gene expression during cell cycle progression is essential for maintaining genome integrity and ensuring that cell proliferation can be stopped by environmental signals. Genetic and proteomic studies during the past two decades revealed remarkable evolutionary conservation of the key mechanisms that control cell cycle-regulated gene expression, including multisubunit DNA-binding DREAM complexes. DREAM complexes containing a retinoblastoma family member, an E2F transcription factor and its dimerization partner, and five proteins related to products of Caenorhabditis elegans multivulva (Muv) class B genes lin-9, lin-37, lin-52, lin-53, and lin-54 (comprising the MuvB core) have been described in diverse organisms, from worms to humans. This review summarizes the current knowledge of the structure, function, and regulation of DREAM complexes in different organisms, as well as the role of DREAM in human disease. Expected final online publication date for the Annual Review of Genetics, Volume 55 is November 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Hayley Walston
- Department of Human and Molecular Genetics, Virginia Commonwealth University, Richmond, Virginia 23298, USA;
| | - Audra N Iness
- School of Medicine, Virginia Commonwealth University, Richmond, Virginia 23298, USA
| | - Larisa Litovchick
- Department of Human and Molecular Genetics, Virginia Commonwealth University, Richmond, Virginia 23298, USA; .,Division of Hematology, Oncology and Palliative Care, Department of Internal Medicine, Virginia Commonwealth University, Richmond, Virginia 23298, USA.,Massey Cancer Center, Richmond, Virginia 23298, USA
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5
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Zhang X, Li M, Jiang X, Ma H, Fan S, Li Y, Yu C, Xu J, Khan R, Jiang H, Shi Q. Nuclear translocation of MTL5 from cytoplasm requires its direct interaction with LIN9 and is essential for male meiosis and fertility. PLoS Genet 2021; 17:e1009753. [PMID: 34388164 PMCID: PMC8386835 DOI: 10.1371/journal.pgen.1009753] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 08/25/2021] [Accepted: 07/29/2021] [Indexed: 01/09/2023] Open
Abstract
Meiosis is essential for the generation of gametes and sexual reproduction, yet the factors and underlying mechanisms regulating meiotic progression remain largely unknown. Here, we showed that MTL5 translocates into nuclei of spermatocytes during zygotene-pachytene transition and ensures meiosis advances beyond pachytene stage. MTL5 shows strong interactions with MuvB core complex components, a well-known transcriptional complex regulating mitotic progression, and the zygotene-pachytene transition of MTL5 is mediated by its direct interaction with the component LIN9, through MTL5 C-terminal 443–475 residues. Male Mtl5c-mu/c-mu mice expressing the truncated MTL5 (p.Ser445Arg fs*3) that lacks the interaction with LIN9 and is detained in cytoplasm showed male infertility and spermatogenic arrest at pachytene stage, same as that of Mtl5 knockout mice, indicating that the interaction with LIN9 is essential for the nuclear translocation and function of MTL5 during meiosis. Our data demonstrated MTL5 translocates into nuclei during the zygotene-pachytene transition to initiate its function along with the MuvB core complex in pachytene spermatocytes, highlighting a new mechanism regulating the progression of male meiosis. Meiosis is essential for spermatogenesis and male fertility. However, the factors regulating the progression of meiosis remain largely unknown. We reported the testis specific protein MTL5 translocated into the nuclei of spermatocytes at the zygotene-pachytene transition by direct interaction with LIN9, which is an essential component of MuvB core complex, to promote meiotic progression beyond the pachytene stage. We also showed that MTL5 pulls down MYBL1 and all of the MuvB core complex (except LIN54) in spermatocytes. Given the known role of the MuvB core complex as a cell cycle regulator in mitotic cells, we suggested that MTL5 promotes meiotic progression along with the MuvB core complex to ensure male fertility. Our results indicated a novel function of the MuvB complex in male meiosis and also shed light on the master regulator proteins that control meiotic progression at the pachytene stage. MTL5 is a novel and germ-cell specific regulator of cell cycle progression to function at a specific stage by nuclear translocation in meiosis.
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Affiliation(s)
- Xingxia Zhang
- First Affiliated Hospital of USTC, Hefei National Laboratory for Physical Sciences at Microscale, School of Basic Medical Sciences, Division of Life Sciences and Medicine, CAS Center for Excellence in Molecular Cell Science, University of Science and Technology of China, Hefei, China
| | - Ming Li
- First Affiliated Hospital of USTC, Hefei National Laboratory for Physical Sciences at Microscale, School of Basic Medical Sciences, Division of Life Sciences and Medicine, CAS Center for Excellence in Molecular Cell Science, University of Science and Technology of China, Hefei, China
| | - Xiaohua Jiang
- First Affiliated Hospital of USTC, Hefei National Laboratory for Physical Sciences at Microscale, School of Basic Medical Sciences, Division of Life Sciences and Medicine, CAS Center for Excellence in Molecular Cell Science, University of Science and Technology of China, Hefei, China
- * E-mail: (XJ); (HJ); (QS)
| | - Hui Ma
- First Affiliated Hospital of USTC, Hefei National Laboratory for Physical Sciences at Microscale, School of Basic Medical Sciences, Division of Life Sciences and Medicine, CAS Center for Excellence in Molecular Cell Science, University of Science and Technology of China, Hefei, China
| | - Suixing Fan
- First Affiliated Hospital of USTC, Hefei National Laboratory for Physical Sciences at Microscale, School of Basic Medical Sciences, Division of Life Sciences and Medicine, CAS Center for Excellence in Molecular Cell Science, University of Science and Technology of China, Hefei, China
| | - Yang Li
- First Affiliated Hospital of USTC, Hefei National Laboratory for Physical Sciences at Microscale, School of Basic Medical Sciences, Division of Life Sciences and Medicine, CAS Center for Excellence in Molecular Cell Science, University of Science and Technology of China, Hefei, China
| | - Changping Yu
- First Affiliated Hospital of USTC, Hefei National Laboratory for Physical Sciences at Microscale, School of Basic Medical Sciences, Division of Life Sciences and Medicine, CAS Center for Excellence in Molecular Cell Science, University of Science and Technology of China, Hefei, China
| | - Jianze Xu
- First Affiliated Hospital of USTC, Hefei National Laboratory for Physical Sciences at Microscale, School of Basic Medical Sciences, Division of Life Sciences and Medicine, CAS Center for Excellence in Molecular Cell Science, University of Science and Technology of China, Hefei, China
| | - Ranjha Khan
- First Affiliated Hospital of USTC, Hefei National Laboratory for Physical Sciences at Microscale, School of Basic Medical Sciences, Division of Life Sciences and Medicine, CAS Center for Excellence in Molecular Cell Science, University of Science and Technology of China, Hefei, China
| | - Hanwei Jiang
- First Affiliated Hospital of USTC, Hefei National Laboratory for Physical Sciences at Microscale, School of Basic Medical Sciences, Division of Life Sciences and Medicine, CAS Center for Excellence in Molecular Cell Science, University of Science and Technology of China, Hefei, China
- * E-mail: (XJ); (HJ); (QS)
| | - Qinghua Shi
- First Affiliated Hospital of USTC, Hefei National Laboratory for Physical Sciences at Microscale, School of Basic Medical Sciences, Division of Life Sciences and Medicine, CAS Center for Excellence in Molecular Cell Science, University of Science and Technology of China, Hefei, China
- * E-mail: (XJ); (HJ); (QS)
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6
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Dan VM, Raveendran RS, Baby S. Resistance to Intervention: Paclitaxel in Breast Cancer. Mini Rev Med Chem 2021; 21:1237-1268. [PMID: 33319669 DOI: 10.2174/1389557520999201214234421] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Revised: 09/22/2020] [Accepted: 11/02/2020] [Indexed: 12/22/2022]
Abstract
Breast cancer stands as the most prevalent cancer in women globally, and contributes to the highest percentage of mortality due to cancer-related deaths in women. Paclitaxel (PTX) is heavily relied on as a frontline chemotherapy drug in breast cancer treatment, especially in advanced metastatic cancer. Generation of resistance to PTX often derails clinical management and adversely affects patient outcomes. Understanding the molecular mechanism of PTX resistance is necessary to device methods to aid in overcoming the resistance. Recent studies exploring the mechanism of development of PTX resistance have led to unveiling of a range novel therapeutic targets. PTX resistance pathways that involve major regulatory proteins/RNAs like RNF8/Twist/ROR1, TLR, ErbB3/ErbB2, BRCA1- IRIS, MENA, LIN9, MiRNA, FoxM1 and IRAK1 have expanded the complexity of resistance mechanisms, and brought newer insights into the development of drug targets. These resistance-related targets can be dealt with synthetic/natural therapeutics in combination with PTX. The present review encompasses the recent understanding of PTX resistance mechanisms in breast cancer and possible therapeutic combinations to overcome resistance.
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Affiliation(s)
- Vipin Mohan Dan
- Microbiology Division, Jawaharlal Nehru Tropical Botanic Garden and Research Institute, Pacha-Palode 695562, Thiruvananthapuram, Kerala, India
| | - Reji Saradha Raveendran
- Microbiology Division, Jawaharlal Nehru Tropical Botanic Garden and Research Institute, Pacha-Palode 695562, Thiruvananthapuram, Kerala, India
| | - Sabulal Baby
- Phytochemistry and Phytopharmacology Division, Jawaharlal Nehru Tropical Botanic Garden and Research Institute, Pacha-Palode 695562, Thiruvananthapuram, Kerala, India
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7
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Cardon T, Franck J, Coyaud E, Laurent EMN, Damato M, Maffia M, Vergara D, Fournier I, Salzet M. Alternative proteins are functional regulators in cell reprogramming by PKA activation. Nucleic Acids Res 2020; 48:7864-7882. [PMID: 32324228 PMCID: PMC7641301 DOI: 10.1093/nar/gkaa277] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2019] [Revised: 04/06/2020] [Accepted: 04/21/2020] [Indexed: 12/28/2022] Open
Abstract
It has been recently shown that many proteins are lacking from reference databases used in mass spectrometry analysis, due to their translation templated on alternative open reading frames. This questions our current understanding of gene annotation and drastically expands the theoretical proteome complexity. The functions of these alternative proteins (AltProts) still remain largely unknown. We have developed a large-scale and unsupervised approach based on cross-linking mass spectrometry (XL-MS) followed by shotgun proteomics to gather information on the functional role of AltProts by mapping them back into known signalling pathways through the identification of their reference protein (RefProt) interactors. We have identified and profiled AltProts in a cancer cell reprogramming system: NCH82 human glioma cells after 0, 16, 24 and 48 h Forskolin stimulation. Forskolin is a protein kinase A activator inducing cell differentiation and epithelial–mesenchymal transition. Our data show that AltMAP2, AltTRNAU1AP and AltEPHA5 interactions with tropomyosin 4 are downregulated under Forskolin treatment. In a wider perspective, Gene Ontology and pathway enrichment analysis (STRING) revealed that RefProts associated with AltProts are enriched in cellular mobility and transfer RNA regulation. This study strongly suggests novel roles of AltProts in multiple essential cellular functions and supports the importance of considering them in future biological studies.
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Affiliation(s)
- Tristan Cardon
- Univ. Lille, Inserm, CHU Lille, U1192-Protéomique Réponse Inflammatoire Spectrométrie de Masse (PRISM), F-59000 Lille, France
| | - Julien Franck
- Univ. Lille, Inserm, CHU Lille, U1192-Protéomique Réponse Inflammatoire Spectrométrie de Masse (PRISM), F-59000 Lille, France
| | - Etienne Coyaud
- Univ. Lille, Inserm, CHU Lille, U1192-Protéomique Réponse Inflammatoire Spectrométrie de Masse (PRISM), F-59000 Lille, France
| | - Estelle M N Laurent
- Univ. Lille, Inserm, CHU Lille, U1192-Protéomique Réponse Inflammatoire Spectrométrie de Masse (PRISM), F-59000 Lille, France
| | - Marina Damato
- Univ. Lille, Inserm, CHU Lille, U1192-Protéomique Réponse Inflammatoire Spectrométrie de Masse (PRISM), F-59000 Lille, France.,Department of Biological and Environmental Sciences and Technologies, University of Salento, 73100 Lecce, Italy
| | - Michele Maffia
- Department of Biological and Environmental Sciences and Technologies, University of Salento, 73100 Lecce, Italy
| | - Daniele Vergara
- Department of Biological and Environmental Sciences and Technologies, University of Salento, 73100 Lecce, Italy
| | - Isabelle Fournier
- Univ. Lille, Inserm, CHU Lille, U1192-Protéomique Réponse Inflammatoire Spectrométrie de Masse (PRISM), F-59000 Lille, France.,Institut Universitaire de France (IUF),75005 Paris, France
| | - Michel Salzet
- Univ. Lille, Inserm, CHU Lille, U1192-Protéomique Réponse Inflammatoire Spectrométrie de Masse (PRISM), F-59000 Lille, France.,Institut Universitaire de France (IUF),75005 Paris, France
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8
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Cibis H, Biyanee A, Dörner W, Mootz HD, Klempnauer KH. Characterization of the zinc finger proteins ZMYM2 and ZMYM4 as novel B-MYB binding proteins. Sci Rep 2020; 10:8390. [PMID: 32439918 PMCID: PMC7242444 DOI: 10.1038/s41598-020-65443-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Accepted: 04/28/2020] [Indexed: 11/09/2022] Open
Abstract
B-MYB, a highly conserved member of the MYB transcription factor family, is expressed ubiquitously in proliferating cells and plays key roles in important cell cycle-related processes, such as control of G2/M-phase transcription, cytokinesis, G1/S-phase progression and DNA-damage reponse. Deregulation of B-MYB function is characteristic of several types of tumor cells, underlining its oncogenic potential. To gain a better understanding of the functions of B-MYB we have employed affinity purification coupled to mass spectrometry to discover novel B-MYB interacting proteins. Here we have identified the zinc-finger proteins ZMYM2 and ZMYM4 as novel B-MYB binding proteins. ZMYM4 is a poorly studied protein whose initial characterization reported here shows that it is highly SUMOylated and that its interaction with B-MYB is stimulated upon induction of DNA damage. Unlike knockdown of B-MYB, which causes G2/M arrest and defective cytokinesis in HEK293 cells, knockdown of ZMYM2 or ZMYM4 have no obvious effects on the cell cycle of these cells. By contrast, knockdown of ZMYM2 strongly impaired the G1/S-phase progression of HepG2 cells, suggesting that ZMYM2, like B-MYB, is required for entry into S-phase in these cells. Overall, our work identifies two novel B-MYB binding partners with possible functions in the DNA-damage response and the G1/S-transition.
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Affiliation(s)
- Hannah Cibis
- Institute for Biochemistry, Westfälische-Wilhelms-Universität, D-48149, Münster, Germany
| | - Abhiruchi Biyanee
- Institute for Biochemistry, Westfälische-Wilhelms-Universität, D-48149, Münster, Germany
| | - Wolfgang Dörner
- Institute for Biochemistry, Westfälische-Wilhelms-Universität, D-48149, Münster, Germany
| | - Henning D Mootz
- Institute for Biochemistry, Westfälische-Wilhelms-Universität, D-48149, Münster, Germany
| | - Karl-Heinz Klempnauer
- Institute for Biochemistry, Westfälische-Wilhelms-Universität, D-48149, Münster, Germany.
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9
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Manna T, Pal K, Jana K, Misra AK. Anti-cancer potential of novel glycosylated 1,4-substituted triazolylchalcone derivatives. Bioorg Med Chem Lett 2019; 29:126615. [DOI: 10.1016/j.bmcl.2019.08.019] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Revised: 08/09/2019] [Accepted: 08/11/2019] [Indexed: 12/18/2022]
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10
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Lai H, Wang R, Li S, Shi Q, Cai Z, Li Y, Liu Y. LIN9 confers paclitaxel resistance in triple negative breast cancer cells by upregulating CCSAP. SCIENCE CHINA-LIFE SCIENCES 2019; 63:419-428. [DOI: 10.1007/s11427-019-9581-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Accepted: 06/16/2019] [Indexed: 12/17/2022]
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11
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Abstract
Human retinoblastoma gene RB1 is the first tumor suppressor gene (TSG) isolated by positional cloning in 1986. RB is extensively studied for its ability to regulate cell cycle by binding to E2F1 and inhibiting the transcriptional activity of the latter. In human embryonic stem cells (ESCs), only a minute trace of RB is found in complex with E2F1. Increased activity of RB triggers differentiation, cell cycle arrest, and cell death. On the other hand, inactivation of the entire RB family (RB1, RBL1, and RBL2) in human ESC induces G2/M arrest and cell death. These observations indicate that both loss and overactivity of RB could be lethal for the stemness of cells. A question arises why inactive RB is required for the survival and stemness of cells? To shed some light on this question, we analyzed the RB-binding proteins. In this review we have focused on 27 RB-binding partners that may have potential roles in different aspects of stem cell biology.
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Affiliation(s)
- M Mushtaq
- Karolinska Institutet, Stockholm, Sweden
| | | | - E V Kashuba
- Karolinska Institutet, Stockholm, Sweden; R.E. Kavetsky Institute of Experimental Pathology, Oncology and Radiobiology, NASU, Kyiv, Ukraine.
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12
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Rashid NN, Rothan HA, Yusoff MSM. The association of mammalian DREAM complex and HPV16 E7 proteins. Am J Cancer Res 2015; 5:3525-3533. [PMID: 26885443 PMCID: PMC4731628] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Accepted: 11/12/2015] [Indexed: 06/05/2023] Open
Abstract
The mammalian DREAM (Drosophila, RB, E2F, and Myb) complex was discovered in 2004 by several research groups. It was initially identified in Drosophila followed by Caenorhaditis elegans and later in mammalian cells. The composition of DREAM is temporally regulated during cell cycle; being associated with E2F-4 and either p107 or p130 in G0/G1 (repressive DREAM complexes) and with B-myb transcription factor in S/G2 (activator DREAM complex). High risk human papillomavirus (HPV) E6 and E7 oncoproteins expression are important for malignant transformation of cervical cancer cells. In particular, the E7 of high risk HPV binds to pRB family members (pRB, p107 and p130) for degradation. It has recently been discovered that the p107 and p130 'pocket proteins' are members of mammalian DREAM complexes. With this understanding, we would like to hypothesise the mammalian DREAM complex could plays a critical role for malignant transformation in cervical cancer cells.
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Affiliation(s)
- Nurshamimi Nor Rashid
- Department of Molecular Medicine, Faculty of Medicine, University of Malaya Kuala Lumpur, Malaysia
| | - Hussin A Rothan
- Department of Molecular Medicine, Faculty of Medicine, University of Malaya Kuala Lumpur, Malaysia
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13
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Guiley KZ, Liban TJ, Felthousen JG, Ramanan P, Litovchick L, Rubin SM. Structural mechanisms of DREAM complex assembly and regulation. Genes Dev 2015; 29:961-74. [PMID: 25917549 PMCID: PMC4421984 DOI: 10.1101/gad.257568.114] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2014] [Indexed: 01/01/2023]
Abstract
To understand the biochemical mechanisms underpinning DREAM function and regulation, Guiley et al. investigated the structural basis for DREAM assembly. Together, the data inform a novel target interface for studying MuvB and p130 function and the design of inhibitors that prevent tumor escape in quiescence. The DREAM complex represses cell cycle genes during quiescence through scaffolding MuvB proteins with E2F4/5 and the Rb tumor suppressor paralog p107 or p130. Upon cell cycle entry, MuvB dissociates from p107/p130 and recruits B-Myb and FoxM1 for up-regulating mitotic gene expression. To understand the biochemical mechanisms underpinning DREAM function and regulation, we investigated the structural basis for DREAM assembly. We identified a sequence in the MuvB component LIN52 that binds directly to the pocket domains of p107 and p130 when phosphorylated on the DYRK1A kinase site S28. A crystal structure of the LIN52–p107 complex reveals that LIN52 uses a suboptimal LxSxExL sequence together with the phosphate at nearby S28 to bind the LxCxE cleft of the pocket domain with high affinity. The structure explains the specificity for p107/p130 over Rb in the DREAM complex and how the complex is disrupted by viral oncoproteins. Based on insights from the structure, we addressed how DREAM is disassembled upon cell cycle entry. We found that p130 and B-Myb can both bind the core MuvB complex simultaneously but that cyclin-dependent kinase phosphorylation of p130 weakens its association. Together, our data inform a novel target interface for studying MuvB and p130 function and the design of inhibitors that prevent tumor escape in quiescence.
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Affiliation(s)
- Keelan Z Guiley
- Department of Chemistry and Biochemistry, University of California at Santa Cruz, Santa Cruz, California 95064, USA
| | - Tyler J Liban
- Department of Chemistry and Biochemistry, University of California at Santa Cruz, Santa Cruz, California 95064, USA
| | - Jessica G Felthousen
- Division of Hematology, Oncology, and Palliative Care, Richmond, Virginia 23298, USA; Massey Cancer Center, Virginia Commonwealth University, Richmond, Virginia 23298, USA
| | - Parameshwaran Ramanan
- Department of Chemistry and Biochemistry, University of California at Santa Cruz, Santa Cruz, California 95064, USA
| | - Larisa Litovchick
- Division of Hematology, Oncology, and Palliative Care, Richmond, Virginia 23298, USA; Massey Cancer Center, Virginia Commonwealth University, Richmond, Virginia 23298, USA
| | - Seth M Rubin
- Department of Chemistry and Biochemistry, University of California at Santa Cruz, Santa Cruz, California 95064, USA;
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Abstract
The dimerization partner, RB-like, E2F and multi-vulval class B (DREAM) complex provides a previously unsuspected unifying role in the cell cycle by directly linking p130, p107, E2F, BMYB and forkhead box protein M1. DREAM mediates gene repression during the G0 phase and coordinates periodic gene expression with peaks during the G1/S and G2/M phases. Perturbations in DREAM complex regulation shift the balance from quiescence towards proliferation and contribute to the increased mitotic gene expression levels that are frequently observed in cancers with a poor prognosis.
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Affiliation(s)
- Subhashini Sadasivam
- Institute for Stem Cell Biology and Regenerative Medicine National Centre for Biological Sciences (TIFR), Bellary Road, Bangalore 560065, India
| | - James A. DeCaprio
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston MA 02215 USA Department of Medicine, Brigham and Women's Hospital, Boston MA 02115 USA Department of Medicine, Harvard Medical School, Boston, MA 02115 USA
- Corresponding author James A. DeCaprio Dana-Farber Cancer Institute 450 Brookline Avenue Boston, MA 02215 Tel: 617-632-3825 Fax: 617-582-8601
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15
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Abstract
The dimerization partner, RB-like, E2F and multi-vulval class B (DREAM) complex provides a previously unsuspected unifying role in the cell cycle by directly linking p130, p107, E2F, BMYB and forkhead box protein M1. DREAM mediates gene repression during the G0 phase and coordinates periodic gene expression with peaks during the G1/S and G2/M phases. Perturbations in DREAM complex regulation shift the balance from quiescence towards proliferation and contribute to the increased mitotic gene expression levels that are frequently observed in cancers with a poor prognosis.
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16
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Kumari G, Ulrich T, Gaubatz S. A role for p38 in transcriptional elongation of p21 (CIP1) in response to Aurora B inhibition. Cell Cycle 2013; 12:2051-60. [PMID: 23759594 DOI: 10.4161/cc.25100] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Aurora kinases play important functions in mitosis. They are overexpressed in many cancers and are targets for anticancer therapy. Inhibition of Aurora B results in cytokinesis failure and polyploidization, leading to activation of the p53 tumor suppressor and its target genes, including p21. The pathways that mediate p21 activation after Aurora B inhibition are not well understood. In this study, we identified a role for the p38 MAP kinase in activation of p21 when Aurora B is inhibited. We show that p38 is required for the acute cell cycle arrest in G 1 and to prevent endoreduplication when Aurora B is inhibited. Stabilization of p53 occurs independently of p38, and recruitment of p53 to the p21 promoter also does not require p38. Instead, enrichment of the elongating form of RNA PolII at the distal region of the p21 gene is strongly reduced when p38 is blocked, indicating that p38 acts in transcriptional elongation of p21. Thus, our results identify an unexpected role of p38 in cell cycle regulation in response to Aurora B inhibition, by promoting the transcriptional elongation of the cell cycle inhibitor p21.
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Affiliation(s)
- Geeta Kumari
- Theodor Boveri Institute, Biocenter, University of Wuerzburg, Wuerzburg, Germany
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17
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Begley U, Sosa MS, Avivar-Valderas A, Patil A, Endres L, Estrada Y, Chan CTY, Su D, Dedon PC, Aguirre-Ghiso JA, Begley T. A human tRNA methyltransferase 9-like protein prevents tumour growth by regulating LIN9 and HIF1-α. EMBO Mol Med 2013; 5:366-83. [PMID: 23381944 PMCID: PMC3598078 DOI: 10.1002/emmm.201201161] [Citation(s) in RCA: 80] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2011] [Revised: 12/05/2012] [Accepted: 12/07/2012] [Indexed: 12/31/2022] Open
Abstract
Emerging evidence points to aberrant regulation of translation as a driver of cell transformation in cancer. Given the direct control of translation by tRNA modifications, tRNA modifying enzymes may function as regulators of cancer progression. Here, we show that a tRNA methyltransferase 9-like (hTRM9L/KIAA1456) mRNA is down-regulated in breast, bladder, colorectal, cervix and testicular carcinomas. In the aggressive SW620 and HCT116 colon carcinoma cell lines, hTRM9L is silenced and its re-expression and methyltransferase activity dramatically suppressed tumour growth in vivo. This growth inhibition was linked to decreased proliferation, senescence-like G0/G1-arrest and up-regulation of the RB interacting protein LIN9. Additionally, SW620 cells re-expressing hTRM9L did not respond to hypoxia via HIF1-α-dependent induction of GLUT1. Importantly, hTRM9L-negative tumours were highly sensitive to aminoglycoside antibiotics and this was associated with altered tRNA modification levels compared to antibiotic resistant hTRM9L-expressing SW620 cells. Our study links hTRM9L and tRNA modifications to inhibition of tumour growth via LIN9 and HIF1-α-dependent mechanisms. It also suggests that aminoglycoside antibiotics may be useful to treat hTRM9L-deficient tumours.
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Affiliation(s)
- Ulrike Begley
- College of Nanoscale Science and Engineering, University at Albany, State University of New York, Albany, NY, USA
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18
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A dual role for the dREAM/MMB complex in the regulation of differentiation-specific E2F/RB target genes. Mol Cell Biol 2012; 32:2110-20. [PMID: 22451490 DOI: 10.1128/mcb.06314-11] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
E2F and RB proteins regulate the expression of genes involved in cell cycle progression, apoptosis, differentiation, and development. Recent studies indicate that they function as part of an evolutionarily conserved multiprotein complex termed dREAM/DREAM/LINC. Here we characterize the role of the Drosophila complex, dREAM, in the regulation of differentiation-specific E2F target genes in actively proliferating cells. These genes are regulated differently from cell cycle-related E2F targets, they do not depend on E2F activation, and E2F/RB repression is maintained throughout the cell cycle. In proliferating cells, their repression is dependent on dREAM. We find that dREAM plays a dual role in their regulation. First, it is required for the stability of the repressive dE2F2/RBF complexes at their promoters during S phase. Second, we find that dREAM is indispensable for both transcriptional repression mechanisms employed at these genes.
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19
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Wolter P, Schmitt K, Fackler M, Kremling H, Probst L, Hauser S, Gruss OJ, Gaubatz S. GAS2L3, a target gene of the DREAM complex, is required for proper cytokinesis and genomic stability. J Cell Sci 2012; 125:2393-406. [PMID: 22344256 DOI: 10.1242/jcs.097253] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The mammalian DREAM complex is a key regulator of cell-cycle-regulated gene transcription and drives the expression of many gene products required for mitosis and cytokinesis. In this study, we characterized GAS2L3, which belongs to the GAS2 family of proteins with putative actin- and microtubule-binding domains as a target gene of DREAM. We found that GAS2L3 localizes to the spindle midzone and the midbody during anaphase and cytokinesis, respectively. Biochemical studies show that GAS2L3 binds to and bundles microtubules as well as F-actin in vitro. Strikingly, the RNAi-mediated knockdown of GAS2L3 results in chromosome segregation defects in multinucleated cells and in cells with multi-lobed nuclei. Likewise, chronic downregulation of GAS2L3 causes chromosome loss and aneuploidy. Time-lapse videomicroscopy experiments in GAS2L3-knockdown cells reveal abnormal oscillation of chromatin and the spindle during cytokinesis. Taken together, our data reveal novel, important roles of GAS2L3 for faithful cell division. Our work thus contributes to the understanding of how DREAM regulates cytokinesis.
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20
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Hauser S, Ulrich T, Wurster S, Schmitt K, Reichert N, Gaubatz S. Loss of LIN9, a member of the DREAM complex, cooperates with SV40 large T antigen to induce genomic instability and anchorage-independent growth. Oncogene 2011; 31:1859-68. [PMID: 21860417 DOI: 10.1038/onc.2011.364] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The DREAM complex is an important regulator of mitotic gene expression during the cell cycle. Here we report that inactivation of LIN9, a subunit of DREAM, results in premature senescence, which can be overcome by the SV40 large T (LT) antigen. Together with the observation that p16(INK4a) and p21(Waf1) are upregulated upon loss of LIN9, these results indicate that senescence is triggered by the pRB and p53 tumor suppressor pathways. We also find that LIN9-null cells that escape senescence are chromosomally instable because of compromised mitotic fidelity. SV40 LT-expressing cells that adapt to the loss of LIN9 can grow anchorage-independently in soft agar, a hallmark of oncogenic transformation. Taken together, these results suggest an important role of mitotic gene regulation in the maintenance of genomic stability and tumor suppression.
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Affiliation(s)
- S Hauser
- Department of Physiological Chemistry I, Biocenter, University of Wuerzburg, Germany
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21
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Tschöp K, Conery AR, Litovchick L, DeCaprio JA, Settleman J, Harlow E, Dyson N. A kinase shRNA screen links LATS2 and the pRB tumor suppressor. Genes Dev 2011; 25:814-30. [PMID: 21498571 PMCID: PMC3078707 DOI: 10.1101/gad.2000211] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2010] [Accepted: 03/07/2011] [Indexed: 01/01/2023]
Abstract
pRB-mediated inhibition of cell proliferation is a complex process that depends on the action of many proteins. However, little is known about the specific pathways that cooperate with the Retinoblastoma protein (pRB) and the variables that influence pRB's ability to arrest tumor cells. Here we describe two shRNA screens that identify kinases that are important for pRB to suppress cell proliferation and pRB-mediated induction of senescence markers. The results reveal an unexpected effect of LATS2, a component of the Hippo pathway, on pRB-induced phenotypes. Partial knockdown of LATS2 strongly suppresses some pRB-induced senescence markers. Further analysis shows that LATS2 cooperates with pRB to promote the silencing of E2F target genes, and that reduced levels of LATS2 lead to defects in the assembly of DREAM (DP, RB [retinoblastoma], E2F, and MuvB) repressor complexes at E2F-regulated promoters. Kinase assays show that LATS2 can phosphorylate DYRK1A, and that it enhances the ability of DYRK1A to phosphorylate the DREAM subunit LIN52. Intriguingly, the LATS2 locus is physically linked with RB1 on 13q, and this region frequently displays loss of heterozygosity in human cancers. Our results reveal a functional connection between the pRB and Hippo tumor suppressor pathways, and suggest that low levels of LATS2 may undermine the ability of pRB to induce a permanent cell cycle arrest in tumor cells.
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Affiliation(s)
- Katrin Tschöp
- Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, Massachusetts 02129, USA
| | - Andrew R. Conery
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Larisa Litovchick
- Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachustts 02215, USA
| | - James A. DeCaprio
- Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachustts 02215, USA
| | - Jeffrey Settleman
- Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, Massachusetts 02129, USA
| | - Ed Harlow
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Nicholas Dyson
- Massachusetts General Hospital Cancer Center, Harvard Medical School, Charlestown, Massachusetts 02129, USA
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22
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Litovchick L, Florens LA, Swanson SK, Washburn MP, DeCaprio JA. DYRK1A protein kinase promotes quiescence and senescence through DREAM complex assembly. Genes Dev 2011; 25:801-13. [PMID: 21498570 PMCID: PMC3078706 DOI: 10.1101/gad.2034211] [Citation(s) in RCA: 213] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2011] [Accepted: 03/01/2011] [Indexed: 12/21/2022]
Abstract
In the absence of growth signals, cells exit the cell cycle and enter into G0 or quiescence. Alternatively, cells enter senescence in response to inappropriate growth signals such as oncogene expression. The molecular mechanisms required for cell cycle exit into quiescence or senescence are poorly understood. The DREAM (DP, RB [retinoblastoma], E2F, and MuvB) complex represses cell cycle-dependent genes during quiescence. DREAM contains p130, E2F4, DP1, and a stable core complex of five MuvB-like proteins: LIN9, LIN37, LIN52, LIN54, and RBBP4. In mammalian cells, the MuvB core dissociates from p130 upon entry into the cell cycle and binds to BMYB during S phase to activate the transcription of genes expressed late in the cell cycle. We used mass spectroscopic analysis to identify phosphorylation sites that regulate the switch of the MuvB core from BMYB to DREAM. Here we report that DYRK1A can specifically phosphorylate LIN52 on serine residue 28, and that this phosphorylation is required for DREAM assembly. Inhibiting DYRK1A activity or point mutation of LIN52 disrupts DREAM assembly and reduces the ability of cells to enter quiescence or undergo Ras-induced senescence. These data reveal an important role for DYRK1A in the regulation of DREAM activity and entry into quiescence.
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Affiliation(s)
- Larisa Litovchick
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts 02215, USA
- Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA
| | | | - Selene K. Swanson
- Stowers Institute for Biomedical Research, Kansas City, Missouri 64110, USA
| | - Michael P. Washburn
- Stowers Institute for Biomedical Research, Kansas City, Missouri 64110, USA
- Department of Pathology and Laboratory Medicine, The University of Kansas Medical Center, Kansas City, Kansas 66160, USA
| | - James A. DeCaprio
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts 02215, USA
- Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA
- Belfer Institute for Applied Cancer Science, Dana-Farber Cancer Institute, Boston, Massachusetts 02215, USA
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Kim YC, Kim SY, Mellado-Gil JM, Yadav H, Neidermyer W, Kamaraju AK, Rane SG. RB regulates pancreas development by stabilizing Pdx1. EMBO J 2011; 30:1563-76. [PMID: 21399612 DOI: 10.1038/emboj.2011.57] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2010] [Accepted: 02/08/2011] [Indexed: 12/15/2022] Open
Abstract
RB is a key substrate of Cdks and an important regulator of the mammalian cell cycle. RB either represses E2Fs that promote cell proliferation or enhances the activity of cell-specific factors that promote differentiation, although the mechanism that facilitates this dual interaction is unclear. Here, we demonstrate that RB associates with and stabilizes pancreatic duodenal homeobox-1 (Pdx-1) that is essential for embryonic pancreas development and adult β-cell function. Interestingly, Pdx-1 utilizes a conserved RB-interaction motif (RIM) that is also present in E2Fs. Point mutations within the RIM reduce RB-Pdx-1 complex formation, destabilize Pdx-1 and promote its proteasomal degradation. Glucose regulates RB and Pdx-1 levels, RB/Pdx-1 complex formation and Pdx-1 degradation. RB occupies the promoters of β-cell-specific genes, and knockdown of RB results in reduced expression of Pdx-1 and its target genes. Further, RB-deficiency in vivo results in reduced pancreas size due to decreased proliferation of Pdx-1(+) pancreatic progenitors, increased apoptosis and aberrant expression of regulators of pancreatic development. These results demonstrate an unanticipated regulatory mechanism for pancreatic development and β-cell function, which involves RB-mediated stabilization of the pancreas-specific transcription factor Pdx-1.
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Affiliation(s)
- Yong-Chul Kim
- Diabetes, Endocrinology, and Obesity Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
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Abstract
Although now dogma, the idea that nonvertebrate organisms such as yeast, worms, and flies could inform, and in some cases even revolutionize, our understanding of oncogenesis in humans was not immediately obvious. Aided by the conservative nature of evolution and the persistence of a cohort of devoted researchers, the role of model organisms as a key tool in solving the cancer problem has, however, become widely accepted. In this review, we focus on the nematode Caenorhabditis elegans and its diverse and sometimes surprising contributions to our understanding of the tumorigenic process. Specifically, we discuss findings in the worm that address a well-defined set of processes known to be deregulated in cancer cells including cell cycle progression, growth factor signaling, terminal differentiation, apoptosis, the maintenance of genome stability, and developmental mechanisms relevant to invasion and metastasis.
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Affiliation(s)
- Natalia V. Kirienko
- University of Wyoming, College of Agriculture, Department of Molecular Biology, Dept 3944, 1000 E. University Avenue, Laramie, WY 82071
| | - Kumaran Mani
- University of Wyoming, College of Agriculture, Department of Molecular Biology, Dept 3944, 1000 E. University Avenue, Laramie, WY 82071
| | - David S. Fay
- University of Wyoming, College of Agriculture, Department of Molecular Biology, Dept 3944, 1000 E. University Avenue, Laramie, WY 82071
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25
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Lin9, a subunit of the mammalian DREAM complex, is essential for embryonic development, for survival of adult mice, and for tumor suppression. Mol Cell Biol 2010; 30:2896-908. [PMID: 20404087 DOI: 10.1128/mcb.00028-10] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The retinoblastoma tumor suppressor protein (pRB) and related p107 and p130 "pocket proteins" function together with the E2F transcription factors to repress gene expression during the cell cycle and development. Recent biochemical studies have identified the multisubunit DREAM pocket protein complexes in Drosophila melanogaster and Caenorhabditis elegans in regulating developmental gene repression. Although a conserved DREAM complex has also been identified in mammalian cells, its physiological function in vivo has not been determined. Here we addressed this question by targeting Lin9, a conserved core subunit of DREAM. We found that LIN9 is essential for early embryonic development and for viability of adult mice. Loss of Lin9 abolishes proliferation and leads to multiple defects in mitosis and cytokinesis because of its requirement for the expression of a large set of mitotic genes, such as Plk1, Aurora A, and Kif20a. While Lin9 heterozygous mice are healthy and normal, they are more susceptible to lung tumorigenesis induced by oncogenic c-Raf than wild-type mice. Together these experiments provide the first direct genetic evidence for the role of LIN9 in development and mitotic gene regulation and they suggest that it may function as a haploinsufficient tumor suppressor.
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26
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Drosophila RB proteins repress differentiation-specific genes via two different mechanisms. Mol Cell Biol 2010; 30:2563-77. [PMID: 20176807 DOI: 10.1128/mcb.01075-09] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
The RB and E2F proteins play important roles in the regulation of cell division, cell death, and development by controlling the expression of genes involved in these processes. The mechanisms of repression by the retinoblastoma protein (pRB) have been extensively studied at cell cycle-regulated promoters. However, little is known about developmentally regulated E2F/RB genes. Here, we have taken advantage of the simplicity of the E2F/RB pathway in flies to inspect the regulation of differentiation-specific target genes. These genes are repressed by dE2F2/RBF and a recently identified RB-containing complex, dREAM/MMB, in a cell type- and cell cycle-independent manner. Our studies indicate that the mechanism of repression differs from that of cell cycle-regulated genes. We find that two different activities are involved in their regulation and that in proliferating cells, both are required to maintain repression. First, dE2F2/RBF and dREAM/MMB employ histone deacetylase (HDAC) activities at promoter regions. Remarkably, we have also uncovered an unconventional mechanism of repression by the Polycomb group (PcG) protein Enhancer of zeste [E(Z)], which is involved in silencing of these genes through the dimethylation of histone H3 Lys27 at nucleosomes located downstream of the transcription start sites (TSS).
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27
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Mannefeld M, Klassen E, Gaubatz S. B-MYB is required for recovery from the DNA damage-induced G2 checkpoint in p53 mutant cells. Cancer Res 2009; 69:4073-80. [PMID: 19383908 DOI: 10.1158/0008-5472.can-08-4156] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
In response to DNA damage, several signaling pathways that arrest the cell cycle in G(1) and G(2) are activated. The down-regulation of mitotic genes contributes to the stable maintenance of the G(2) arrest. The human LINC or DREAM complex, together with the B-MYB transcription factor, plays an essential role in the expression of G(2)-M genes. Here, we show that DNA damage results in the p53-dependent binding of p130 and E2F4 to LINC and the dissociation of B-MYB from LINC. We find that B-MYB fails to dissociate from LINC in p53 mutant cells, that this contributes to increased G(2)-M gene expression in response to DNA damage in these cells, and, importantly, that B-MYB is required for recovery from the G(2) DNA damage checkpoint in p53-negative cells. Reanalysis of microarray expression data sets revealed that high levels of B-MYB correlate with a p53 mutant status and an advanced tumor stage in primary human breast cancer. Taken together, these data suggest that B-MYB/LINC plays an important role in the DNA damage response downstream of p53.
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Affiliation(s)
- Mirijam Mannefeld
- Department of Physiological Chemistry I, Biocenter, University of Würzburg, Würzburg, Germany
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28
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Hassan MR, Hossain MM, Bailey J, Macintyre G, Ho JWK, Ramamohanarao K. A voting approach to identify a small number of highly predictive genes using multiple classifiers. BMC Bioinformatics 2009; 10 Suppl 1:S19. [PMID: 19208118 PMCID: PMC2648737 DOI: 10.1186/1471-2105-10-s1-s19] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Background Microarray gene expression profiling has provided extensive datasets that can describe characteristics of cancer patients. An important challenge for this type of data is the discovery of gene sets which can be used as the basis of developing a clinical predictor for cancer. It is desirable that such gene sets be compact, give accurate predictions across many classifiers, be biologically relevant and have good biological process coverage. Results By using a new type of multiple classifier voting approach, we have identified gene sets that can predict breast cancer prognosis accurately, for a range of classification algorithms. Unlike a wrapper approach, our method is not specialised towards a single classification technique. Experimental analysis demonstrates higher prediction accuracies for our sets of genes compared to previous work in the area. Moreover, our sets of genes are generally more compact than those previously proposed. Taking a biological viewpoint, from the literature, most of the genes in our sets are known to be strongly related to cancer. Conclusion We show that it is possible to obtain superior classification accuracy with our approach and obtain a compact gene set that is also biologically relevant and has good coverage of different biological processes.
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Affiliation(s)
- Md Rafiul Hassan
- Department of Computer Science and Software Engineering, The University of Melbourne, Victoria 3010, Australia.
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29
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Wan L, Li D, Zhang D, Liu X, Fu WJ, Zhu L, Deng M, Sun F, Qian M. Conservation and implications of eukaryote transcriptional regulatory regions across multiple species. BMC Genomics 2008; 9:623. [PMID: 19099599 PMCID: PMC2640395 DOI: 10.1186/1471-2164-9-623] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2008] [Accepted: 12/20/2008] [Indexed: 01/14/2023] Open
Abstract
BACKGROUND Increasing evidence shows that whole genomes of eukaryotes are almost entirely transcribed into both protein coding genes and an enormous number of non-protein-coding RNAs (ncRNAs). Therefore, revealing the underlying regulatory mechanisms of transcripts becomes imperative. However, for a complete understanding of transcriptional regulatory mechanisms, we need to identify the regions in which they are found. We will call these transcriptional regulation regions, or TRRs, which can be considered functional regions containing a cluster of regulatory elements that cooperatively recruit transcriptional factors for binding and then regulating the expression of transcripts. RESULTS We constructed a hierarchical stochastic language (HSL) model for the identification of core TRRs in yeast based on regulatory cooperation among TRR elements. The HSL model trained based on yeast achieved comparable accuracy in predicting TRRs in other species, e.g., fruit fly, human, and rice, thus demonstrating the conservation of TRRs across species. The HSL model was also used to identify the TRRs of genes, such as p53 or OsALYL1, as well as microRNAs. In addition, the ENCODE regions were examined by HSL, and TRRs were found to pervasively locate in the genomes. CONCLUSION Our findings indicate that 1) the HSL model can be used to accurately predict core TRRs of transcripts across species and 2) identified core TRRs by HSL are proper candidates for the further scrutiny of specific regulatory elements and mechanisms. Meanwhile, the regulatory activity taking place in the abundant numbers of ncRNAs might account for the ubiquitous presence of TRRs across the genome. In addition, we also found that the TRRs of protein coding genes and ncRNAs are similar in structure, with the latter being more conserved than the former.
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Affiliation(s)
- Lin Wan
- School of Mathematical Sciences, Peking University, Beijing 100871, PR China
- Center for Theoretical Biology, Peking University, Beijing 100871, PR China
| | - Dayong Li
- State Key Laboratory of Plant Genomics and National Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, PR China
| | - Donglei Zhang
- State Key Laboratory of Plant Genomics and National Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, PR China
| | - Xue Liu
- State Key Laboratory of Plant Genomics and National Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, PR China
| | - Wenjiang J Fu
- Department of Epidemiology, Michigan State University, East Lansing, Michigan 48824, USA
| | - Lihuang Zhu
- State Key Laboratory of Plant Genomics and National Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, PR China
| | - Minghua Deng
- School of Mathematical Sciences, Peking University, Beijing 100871, PR China
- Center for Theoretical Biology, Peking University, Beijing 100871, PR China
| | - Fengzhu Sun
- MOE Key Laboratory of Bioinformatics and Bioinformatics Division, TNLIST/Department of Automation, Tsinghua University, Beijing 100871, PR China
- Molecular and Computational Biology Program, University of Southern California, Los Angeles, California 90089, USA
| | - Minping Qian
- School of Mathematical Sciences, Peking University, Beijing 100871, PR China
- Center for Theoretical Biology, Peking University, Beijing 100871, PR China
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Targeted screening of SiRNA directed HBV polymerase gene for effective inhibition of HBV expression. ACTA ACUST UNITED AC 2008; 28:266-71. [DOI: 10.1007/s11596-008-0308-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2008] [Indexed: 02/06/2023]
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31
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Georlette D, Ahn S, MacAlpine DM, Cheung E, Lewis PW, Beall EL, Bell SP, Speed T, Manak JR, Botchan MR. Genomic profiling and expression studies reveal both positive and negative activities for the Drosophila Myb MuvB/dREAM complex in proliferating cells. Genes Dev 2007; 21:2880-96. [PMID: 17978103 DOI: 10.1101/gad.1600107] [Citation(s) in RCA: 122] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Myb-MuvB (MMB)/dREAM is a nine-subunit complex first described in Drosophila as a repressor of transcription, dependent on E2F2 and the RBFs. Myb, an integral member of MMB, curiously plays no role in the silencing of the test genes previously analyzed. Moreover, Myb plays an activating role in DNA replication in Drosophila egg chamber follicle cells. The essential functions for Myb are executed as part of MMB. This duality of function lead to the hypothesis that MMB, which contains both known activator and repressor proteins, might function as part of a switching mechanism that is dependent on DNA sites and developmental context. Here, we used proliferating Drosophila Kc tissue culture cells to explore both the network of genes regulated by MMB (employing RNA interference and microarray expression analysis) and the genomic locations of MMB following chromatin immunoprecipitation (ChIP) and tiling array analysis. MMB occupied 3538 chromosomal sites and was promoter-proximal to 32% of Drosophila genes. MMB contains multiple DNA-binding factors, and the data highlighted the combinatorial way by which the complex was targeted and utilized for regulation. Interestingly, only a subset of chromatin-bound complexes repressed genes normally expressed in a wide range of developmental pathways. At many of these sites, E2F2 was critical for repression, whereas at other nonoverlapping sites, Myb was critical for repression. We also found sites where MMB was a positive regulator of transcript levels that included genes required for mitotic functions (G2/M), which may explain some of the chromosome instability phenotypes attributed to loss of Myb function in myb mutants.
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Affiliation(s)
- Daphne Georlette
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, California 94720, USA
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Hofstetter JR, Hitzemann RJ, Belknap JK, Walter NAR, McWeeney SK, Mayeda AR. Characterization of the quantitative trait locus for haloperidol-induced catalepsy on distal mouse chromosome 1. GENES BRAIN AND BEHAVIOR 2007; 7:214-23. [PMID: 17696997 DOI: 10.1111/j.1601-183x.2007.00340.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We report here the confirmation of the quantitative trait locus for haloperidol-induced catalepsy on distal chromosome (Chr) 1. We determined that this quantitative trait locus was captured in the B6.D2-Mtv7a/Ty congenic mouse strain, whose introgressed genomic interval extends from approximately 169.1 to 191.3 Mb. We then constructed a group of overlapping interval-specific congenic strains to further break up the interval and remapped the locus between 177.5 and 183.4 Mb. We next queried single nucleotide polymorphism (SNP) data sets and identified three genes with nonsynonymous coding SNPs in the quantitative trait locus. We also queried two brain gene expression data sets and found five known genes in this 5.9-Mb interval that are differentially expressed in both whole brain and striatum. Three of the candidate quantitative trait genes were differentially expressed using quantitative real-time polymerase chain reaction analyses. Overall, the current study illustrates how multiple approaches, including congenic fine mapping, SNP analysis and microarray gene expression screens, can be integrated both to reduce the quantitative trait locus interval significantly and to detect promising candidate quantitative trait genes.
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Affiliation(s)
- J R Hofstetter
- Department of Veterans Affairs, Richard L. Roudebush Medical Center, Indianapolis, IN 46202, USA.
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33
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Litovchick L, Sadasivam S, Florens L, Zhu X, Swanson SK, Velmurugan S, Chen R, Washburn MP, Liu XS, DeCaprio JA. Evolutionarily conserved multisubunit RBL2/p130 and E2F4 protein complex represses human cell cycle-dependent genes in quiescence. Mol Cell 2007; 26:539-51. [PMID: 17531812 DOI: 10.1016/j.molcel.2007.04.015] [Citation(s) in RCA: 299] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2006] [Revised: 03/12/2007] [Accepted: 04/20/2007] [Indexed: 02/02/2023]
Abstract
The mammalian Retinoblastoma (RB) family including pRB, p107, and p130 represses E2F target genes through mechanisms that are not fully understood. In D. melanogaster, RB-dependent repression is mediated in part by the multisubunit protein complex Drosophila RBF, E2F, and Myb (dREAM) that contains homologs of the C. elegans synthetic multivulva class B (synMuvB) gene products. Using an integrated approach combining proteomics, genomics, and bioinformatic analyses, we identified a p130 complex termed DP, RB-like, E2F, and MuvB (DREAM) that contains mammalian homologs of synMuvB proteins LIN-9, LIN-37, LIN-52, LIN-54, and LIN-53/RBBP4. DREAM bound to more than 800 human promoters in G0 and was required for repression of E2F target genes. In S phase, MuvB proteins dissociated from p130 and formed a distinct submodule that bound MYB. This work reveals an evolutionarily conserved multisubunit protein complex that contains p130 and E2F4, but not pRB, and mediates the repression of cell cycle-dependent genes in quiescence.
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Affiliation(s)
- Larisa Litovchick
- Department of Medical Oncology, Dana-Farber Cancer Institute and Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, 44 Binney Street, Boston, MA 02115, USA
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Pilkinton M, Sandoval R, Barrett K, Tian X, Colamonici OR. Mip/LIN-9 can inhibit cell proliferation independent of the pocket proteins. Blood Cells Mol Dis 2007; 39:272-7. [PMID: 17618148 PMCID: PMC2184568 DOI: 10.1016/j.bcmd.2007.05.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2007] [Accepted: 05/21/2007] [Indexed: 12/21/2022]
Abstract
Progression through the G1-phase of the cell cycle requires that cyclin D and CDK4 phosphorylate pRB and the other pocket proteins, p107 and p130. Cyclin E and CDK2 further phosphorylate pRB to complete its inactivation and allow the cell to enter S-phase. These phosphorylation events lead to the inactivation of the antiproliferative effect of the pocket proteins. The pocket proteins are the main targets of CDK4, and its unregulated activity can contribute to carcinogenesis. Mip/LIN9 is a recently described protein with growth suppressor, as well as growth promoting effects due to its ability to stabilize B-Myb and induce genes required for S phase and mitosis. The finding that a mutation that deletes the first 84 amino acids of Mip/LIN-9 corrects the defects of the CDK4 knockout mouse suggests that it should have a growth repressor effect that is blocked by CDK4. However, overexpression of cyclin D only partially blocks the inhibitory effect of Mip/LIN-9 on cell proliferation. Here, we performed experiments to further understand the antiproliferative effect of Mip/LIN-9 within the context of the pocket proteins. Our results suggest that there is a pocket protein-independent mechanism of the Mip/LIN-9 antiproliferative effect since it can be observed in cells with ablation of the three members of the family, and in NIH3T3 cells expressing the adenovirus E1A-12S protein. Altogether, the independence from the pocket proteins and the partial blockade of the antiproliferative effect produced by expression of cyclin D suggest that the role of Mip/LIN-9 downstream of CDK4 may be more closely related to the activation of B-Myb and the induction of S/M genes. Importantly, the regulatory effect of CDK4 is not due to direct phosphorylation of Mip/LIN-9 by this kinase or even CDK2, suggesting an indirect mechanism such as phosphorylation of the pocket proteins.
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Affiliation(s)
| | | | | | | | - Oscar R. Colamonici
- Address correspondence to: Oscar R. Colamonici, M.D., University of Illinois, Department of Pharmacology, 835 S. Wolcott, Room E403 (M/C 868), Chicago, IL 60612. Phone: 312-413-4113, Fax: 312-413-4140 E-mail:
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Pilkinton M, Sandoval R, Colamonici OR. Mammalian Mip/LIN-9 interacts with either the p107, p130/E2F4 repressor complex or B-Myb in a cell cycle-phase-dependent context distinct from the Drosophila dREAM complex. Oncogene 2007; 26:7535-43. [PMID: 17563750 DOI: 10.1038/sj.onc.1210562] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Mammalian Mip/LIN-9 is a cell cycle regulatory protein that is negatively regulated by CDK4/cyclin D. It has been demonstrated that Mip/LIN-9 collaborates with B-Myb during S and G(2)/M in the induction of cyclins A and B, and CDK1. The ortholog of Mip/LIN-9 in Drosophila, Mip130, is part of a large multisubunit protein complex that includes RBF, repressor E2Fs and Myb, in what was termed the dREAM complex. A similar complex, although lacking B-Myb, was also described in Caenorhabditis elegans. Here, we demonstrate that unlike Drosophila, Mip/LIN-9 has mutually exclusive and cell cycle-phase-specific interactions with the mammalian orthologs of the dREAM complex. In G(0)/early G(1), Mip/LIN-9 forms a complex with E2F4 and p107 or p130, while in late G(1)/S phase, it associates with B-Myb. The separation of Mip/LIN-9 from p107,p130/E2F4 is likely driven by phosphorylation of the pocket proteins by CDK4 since Mip/LIN-9 fails to interact with phosphorylated forms of p107,p130. Importantly, the repressor complex that Mip/LIN-9 forms with p107 takes functional precedence over the transcriptional activation linked to the Mip/LIN-9 and B-Myb interaction since expression of p107 blocks the activation of the cyclin B promoter triggered by B-Myb and Mip/LIN-9.
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Affiliation(s)
- M Pilkinton
- Department of Pharmacology, University of Illinois, Chicago, IL 60612, USA
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36
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Beall EL, Lewis PW, Bell M, Rocha M, Jones DL, Botchan MR. Discovery of tMAC: a Drosophila testis-specific meiotic arrest complex paralogous to Myb-Muv B. Genes Dev 2007; 21:904-19. [PMID: 17403774 PMCID: PMC1847709 DOI: 10.1101/gad.1516607] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The Drosophila Myb-Muv B (MMB)/dREAM complex regulates gene expression and DNA replication site-specifically, but its activities in vivo have not been thoroughly explored. In ovarian amplification-stage follicle cell nuclei, the largest subunit, Mip130, is a negative regulator of replication, whereas another subunit, Myb, is a positive regulator. Here, we identified a mutation in mip40 and generated a mutation in mip120, two additional MMB subunits. Both mutants were viable, but mip120 mutants had many complex phenotypes including shortened longevity and severe eye defects. mip40 mutant females had severely reduced fertility, whereas mip120 mutant females were sterile, substantiating ovarian regulatory role(s) for MMB. Myb accumulation and binding to polytene chromosomes was dependent on the core factors of the MMB complex. In contrast to the documented mip130 mutant phenotypes, both mip40 and mip120 mutant males were sterile. We purified Mip40-containing complexes from testis nuclear extracts and identified tMAC, a new testis-specific meiotic arrest complex that contained Mip40, Caf1/p55, the Mip130 family member, Always early (Aly), and a Mip120 family member, Tombola (Tomb). Together, these data demonstrate that MMB serves diverse roles in different developmental pathways, and members of MMB can be found in alternative, noninteracting complexes in different cell types.
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Affiliation(s)
- Eileen L. Beall
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California 94720, USA
| | - Peter W. Lewis
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California 94720, USA
| | - Maren Bell
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California 94720, USA
| | - Michael Rocha
- The Salk Institute for Biological Studies, Laboratory of Genetics, La Jolla, California 92037, USA
| | - D. Leanne Jones
- The Salk Institute for Biological Studies, Laboratory of Genetics, La Jolla, California 92037, USA
| | - Michael R. Botchan
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California 94720, USA
- Corresponding author.E-MAIL ; FAX (510) 643-1729
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37
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Jiang J, Benson E, Bausek N, Doggett K, White-Cooper H. Tombola, a tesmin/TSO1-family protein, regulates transcriptional activation in the Drosophila male germline and physically interacts with always early. Development 2007; 134:1549-59. [PMID: 17360778 PMCID: PMC2229809 DOI: 10.1242/dev.000521] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
During male gametogenesis, a developmentally regulated and cell type-specific transcriptional programme is activated in primary spermatocytes to prepare for differentiation of sperm. The Drosophila aly-class meiotic-arrest loci (aly, comr, achi/vis and topi) are essential for activation of transcription of many differentiation-specific genes, and several genes important for meiotic cell cycle progression, thus linking meiotic divisions to cellular differentiation during spermatogenesis. Protein interaction studies suggest that the aly-class gene products form a chromatin-associated complex in primary spermatocytes. We identify, clone and characterise a new aly-class meiotic-arrest gene, tombola (tomb), which encodes a testis-specific CXC-domain protein that interacts with Aly. The tomb mutant phenotype is more like that of aly and comr mutants than that of achi/vis or topi mutants in terms of target gene profile and chromosome morphology. tomb encodes a chromatin-associated protein required for localisation of Aly and Comr, but not Topi, to chromatin Reciprocally, aly and comr, but not topi or achi/vis, are required to maintain the normal localisation of Tomb. tomb and aly might be components of a complex paralogous to the Drosophila dREAM/Myb-MuvB and C. elegans DRM transcriptional regulatory complexes.
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Affiliation(s)
- Jianqiao Jiang
- Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, UK
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38
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The SynMuv genes of Caenorhabditis elegans in vulval development and beyond. Dev Biol 2007; 306:1-9. [PMID: 17434473 DOI: 10.1016/j.ydbio.2007.03.016] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2006] [Revised: 02/26/2007] [Accepted: 03/05/2007] [Indexed: 01/12/2023]
Abstract
For a nonessential diminutive organ comprised of only 22 nuclei, the Caenorhabditis elegans vulva has done very well for itself. The status of the vulva as an overachiever is in part due to its inherent structural simplicity as well as to the intricate regulation of its induction and development. Studies over the past twenty years have shown the vulva to be a microcosm for organogenesis and a model for the integration of complex signaling pathways. Furthermore, many of these signaling molecules are themselves associated with cancer in mammals. This review focuses on what is perhaps the most intriguing and complex story to emerge from these studies thus far, the role of the Synthetic Multivulval (SynMuv) genes in controlling vulval cell-fate adoption. Recent advances have led to a greater mechanistic understanding of how these genes function during vulval development and have also identified roles for these genes in diverse developmental processes.
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Cobrinik D, Francis RO, Abramson DH, Lee TC. Rb induces a proliferative arrest and curtails Brn-2 expression in retinoblastoma cells. Mol Cancer 2006; 5:72. [PMID: 17163992 PMCID: PMC1764425 DOI: 10.1186/1476-4598-5-72] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2006] [Accepted: 12/12/2006] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND Retinoblastoma is caused by loss of the Rb protein in early retinal cells. Although numerous Rb functions have been identified, Rb effects that specifically relate to the suppression of retinoblastoma have not been defined. RESULTS In this study, we examined the effects of restoring Rb to Y79 retinoblastoma cells, using novel retroviral and lentiviral vectors that co-express green fluorescent protein (GFP). The lentiviral vector permitted transduction with sufficient efficiency to perform biochemical analyses. Wild type Rb (RbWT) and to a lesser extent the low penetrance mutant Rb661W induced a G0/G1 arrest associated with induction of p27KIP1 and repression of cyclin E1 and cyclin E2. Microarray analyses revealed that in addition to down-regulating E2F-responsive genes, Rb repressed expression of Brn-2 (POU3F2), which is implicated as an important transcriptional regulator in retinal progenitor cells and other neuroendocrine cell types. The repression of Brn-2 was a specific Rb effect, as ectopic p27 induced a G0/G1 block, but enhanced, rather than repressed, Brn-2 expression. CONCLUSION In addition to Rb effects that occur in many cell types, Rb regulates a gene that selectively governs the behavior of late retinal progenitors and related cells.
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Affiliation(s)
- David Cobrinik
- Margaret M. Dyson Vision Research Institute, Weill Medical College of Cornell University, New York, NY 10021, USA
- Department of Ophthalmology, Weill Medical College of Cornell University, New York, NY 10021, USA
| | - Richard O Francis
- Department of Pathology, Columbia University College of Physicians and Surgeons, New York, NY 10032, USA
| | - David H Abramson
- Department of Ophthalmology, Weill Medical College of Cornell University, New York, NY 10021, USA
- Ophthalmic Oncology Service, Memorial Sloan-Kettering Cancer Center, New York, NY 10021, USA
| | - Thomas C Lee
- Margaret M. Dyson Vision Research Institute, Weill Medical College of Cornell University, New York, NY 10021, USA
- Department of Ophthalmology, Weill Medical College of Cornell University, New York, NY 10021, USA
- Division of Ophthalmology, Department of Surgery, Childrens Hospital Los Angeles, Los Angeles, CA, USA
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40
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Osterloh L, von Eyss B, Schmit F, Rein L, Hübner D, Samans B, Hauser S, Gaubatz S. The human synMuv-like protein LIN-9 is required for transcription of G2/M genes and for entry into mitosis. EMBO J 2006; 26:144-57. [PMID: 17159899 PMCID: PMC1782375 DOI: 10.1038/sj.emboj.7601478] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2006] [Accepted: 11/16/2006] [Indexed: 01/06/2023] Open
Abstract
Regulated gene expression is critical for the proper timing of cell cycle transitions. Here we report that human LIN-9 has an important function in transcriptional regulation of G2/M genes. Depletion of LIN-9 by RNAi in human fibroblasts strongly impairs proliferation and delays progression from G2 to M. We identify a cluster of G2/M genes as direct targets of LIN-9. Activation of these genes is linked to an association between LIN-9 and B-MYB. Chromatin immunoprecipitation assays revealed binding of both LIN-9 and B-MYB to the promoters of G2/M regulated genes. Depletion of B-MYB recapitulated the biological outcome of LIN-9 knockdown, including impaired proliferation and reduced expression of G2/M genes. These data suggest a critical role for human LIN-9, together with B-MYB, in the activation of genes that are essential for progression into mitosis.
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Affiliation(s)
- Lisa Osterloh
- Department of Physiological Chemistry I, Biocenter, University of Würzburg, Am Hubland, Würzburg, Germany
| | - Björn von Eyss
- Department of Physiological Chemistry I, Biocenter, University of Würzburg, Am Hubland, Würzburg, Germany
| | - Fabienne Schmit
- Department of Physiological Chemistry I, Biocenter, University of Würzburg, Am Hubland, Würzburg, Germany
| | - Lena Rein
- Department of Physiological Chemistry I, Biocenter, University of Würzburg, Am Hubland, Würzburg, Germany
| | - Denise Hübner
- Department of Physiological Chemistry I, Biocenter, University of Würzburg, Am Hubland, Würzburg, Germany
| | - Birgit Samans
- Institute for Molecular Biology and Tumor Research, Philipps-University Marburg, Marburg, Germany
| | - Stefanie Hauser
- Department of Physiological Chemistry I, Biocenter, University of Würzburg, Am Hubland, Würzburg, Germany
| | - Stefan Gaubatz
- Department of Physiological Chemistry I, Biocenter, University of Würzburg, Am Hubland, Würzburg, Germany
- Department of Physiological Chemistry I, Biocenter, University of Würzburg, Am Hubland, 97074 Würzburg, Germany. Tel.: +49 931 888 4138; Fax: +49 931 888 4150; E-mail:
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Pilkinton M, Sandoval R, Song J, Ness SA, Colamonici OR. Mip/LIN-9 regulates the expression of B-Myb and the induction of cyclin A, cyclin B, and CDK1. J Biol Chem 2006; 282:168-75. [PMID: 17098733 DOI: 10.1074/jbc.m609924200] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Members of the novel family of proteins that include Drosophila Mip130, Caenorhabditis elegans LIN-9, and mammalian LIN-9 intervene in different cellular functions such as regulation of transcription, differentiation, transformation, and cell cycle progression. Here we demonstrate that LIN-9, designated as Mip/LIN-9, interacts with B-Myb but not with c-Myb or A-Myb. Mip/LIN-9 regulates the expression of B-Myb in a post-transcriptional manner, and its depletion not only decreases the level of the B-Myb protein but also affects the expression of S phase and mitotic genes (i.e. cyclin A, CDK1, and cyclin B). The critical role of Mip/LIN-9 on the expression of S and G(2)/M genes is further supported by the finding that coexpression of Mip/LIN-9 and B-Myb results in the activation of cyclin A and cyclin B promoter-luciferase reporters, and both proteins are detected on the cyclin A and B promoters. Interestingly, although Mip/LIN-9 promoter occupancy peaks earlier than B-Myb, the highest levels of expression of cyclins A and B correlate with the maximum binding of B-Myb to these promoters. These data support the concept that Mip/LIN-9 is required for the expression of B-Myb, and both proteins collaborate in the control of the cell cycle progression via the regulation of S phase and mitotic cyclins.
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Affiliation(s)
- Mark Pilkinton
- Department of Pharmacology, University of Illinois, Chicago, Illinois 60612, USA
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42
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Harrison MM, Ceol CJ, Lu X, Horvitz HR. Some C. elegans class B synthetic multivulva proteins encode a conserved LIN-35 Rb-containing complex distinct from a NuRD-like complex. Proc Natl Acad Sci U S A 2006; 103:16782-7. [PMID: 17075059 PMCID: PMC1636532 DOI: 10.1073/pnas.0608461103] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The Caenorhabditis elegans synthetic multivulva (synMuv) genes act redundantly to antagonize the specification of vulval cell fates, which are promoted by an RTK/Ras pathway. At least 26 synMuv genes have been genetically identified, several of which encode proteins with homologs that act in chromatin remodeling or transcriptional repression. Here we report the molecular characterization of two synMuv genes, lin-37 and lin-54. We show that lin-37 and lin-54 encode proteins in a complex with at least seven synMuv proteins, including LIN-35, the only C. elegans homolog of the mammalian tumor suppressor Rb. Biochemical analyses of mutants suggest that LIN-9, LIN-53, and LIN-54 are required for the stable formation of this complex. This complex is distinct from a second complex of synMuv proteins with a composition similar to that of the mammalian Nucleosome Remodeling and Deacetylase complex. The class B synMuv complex we identified is evolutionarily conserved and likely functions in transcriptional repression and developmental regulation.
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Affiliation(s)
- Melissa M. Harrison
- Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Craig J. Ceol
- Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Xiaowei Lu
- Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - H. Robert Horvitz
- Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139
- To whom correspondence should be addressed. E-mail:
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43
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Abstract
The Rb protein is a tumor suppressor, which plays a pivotal role in the negative control of the cell cycle and in tumor progression. It has been shown that Rb protein (pRb) is responsible for a major G1 checkpoint, blocking S-phase entry and cell growth. The retinoblastoma family includes three members, Rb/p105, p107 and Rb2/p130, collectively referred to as 'pocket proteins'. The pRb protein represses gene transcription, required for transition from G1 to S phase, by directly binding to the transactivation domain of E2F and by binding to the promoter of these genes as a complex with E2F. pRb represses transcription also by remodeling chromatin structure through interaction with proteins such as hBRM, BRG1, HDAC1 and SUV39H1, which are involved in nucleosome remodeling, histone acetylation/deacetylation and methylation, respectively. Loss of pRb functions may induce cell cycle deregulation and so lead to a malignant phenotype. Gene inactivation of pRB through chromosomal mutations is one of the principal reasons for retinoblastoma tumor development. Functional inactivation of pRb by viral oncoprotein binding is also shown in many neoplasias such as cervical cancer, mesothelioma and AIDS-related Burkitt's lymphoma.
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Affiliation(s)
- C Giacinti
- Sbarro Institute for Cancer Research and Molecular Medicine, Temple University, Philadelphia, PA 19122, USA
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44
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Chi W, Reinke V. Promotion of oogenesis and embryogenesis in the C. elegans gonad by EFL-1/DPL-1 (E2F) does not require LIN-35 (pRB). Development 2006; 133:3147-57. [PMID: 16854972 DOI: 10.1242/dev.02490] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
In Caenorhabditis elegans, EFL-1 (E2F), DPL-1 (DP) and LIN-35 (pRb) act coordinately in somatic tissues to inhibit ectopic cell division, probably by repressing the expression of target genes. EFL-1, DPL-1 and LIN-35 are also present in the germline, but do not always act together. Strong loss-of-function mutations in either efl-1 or dpl-1 cause defects in oogenesis that result in sterility, while lin-35 mutants are fertile with reduced broods. Microarray-based expression profiling of dissected gonads from efl-1, dpl-1 and lin-35 mutants reveals that EFL-1 and DPL-1 promote expression of an extensively overlapping set of target genes, consistent with the expectation that these two proteins function as a heterodimer. Regulatory regions upstream of many of these target genes have a canonical E2F-binding site, suggesting that their regulation by EFL-1/DPL-1 is direct. Many EFL-1/DPL-1 responsive genes encode proteins required for oogenesis and early embryogenesis, rather than cell cycle components. By contrast, LIN-35 appears to function primarily as a repressor of gene expression in the germline, and the genes that it acts on are for the most part distinct from those regulated by EFL-1 and/or DPL-1. Thus, in vivo, C. elegans E2F directly promotes oogenesis and embryogenesis through the activation of a tissue-specific transcriptional program that does not require LIN-35.
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Affiliation(s)
- Woo Chi
- Department of Genetics, Yale University School of Medicine, New Haven, CT 06520, USA
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Sandoval R, Xue J, Tian X, Barrett K, Pilkinton M, Ucker DS, Raychaudhuri P, Kineman RD, Luque RM, Baida G, Zou X, Valli VE, Cook JL, Kiyokawa H, Colamonici OR. A mutant allele of BARA/LIN-9 rescues the cdk4-/- phenotype by releasing the repression on E2F-regulated genes. Exp Cell Res 2006; 312:2465-75. [PMID: 16730350 DOI: 10.1016/j.yexcr.2006.04.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2005] [Revised: 04/05/2006] [Accepted: 04/10/2006] [Indexed: 11/22/2022]
Abstract
It has been proposed that C. elegans LIN-9 functions downstream of CDK4 in a pathway that regulates cell proliferation. Here, we report that mammalian BARA/LIN-9 is a predominantly nuclear protein that inhibits cell proliferation. More importantly, we demonstrate that BARA/LIN-9 also acts downstream of cyclin D/CDK4 in mammalian cells since (i) its antiproliferative effect is partially blocked by coexpression of cyclin D1, and (ii) a mutant form that lacks the first 84 amino acids rescues several phenotypic alterations observed in mice null for cdk4. Interestingly, mutation of BARA/LIN-9 restores the expression of E2F target genes in CDK4 null MEFs, indicating that the wild-type protein plays a role in the expression of genes required for the G1/S transition.
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Affiliation(s)
- Raudel Sandoval
- Department of Pharmacology, University of Illinois at Chicago, IL 60612, USA
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MacWilliams H, Doquang K, Pedrola R, Dollman G, Grassi D, Peis T, Tsang A, Ceccarelli A. A retinoblastoma ortholog controls stalk/spore preference in Dictyostelium. Development 2006; 133:1287-97. [PMID: 16495312 DOI: 10.1242/dev.02287] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
We describe rblA, the Dictyostelium ortholog of the retinoblastoma susceptibility gene Rb. In the growth phase, rblA expression is correlated with several factors that lead to 'preference' for the spore pathway. During multicellular development, expression increases 200-fold in differentiating spores. rblA-null strains differentiate stalk cells and spores normally, but in chimeras with wild type, the mutant shows a strong preference for the stalk pathway. rblA-null cells are hypersensitive to the stalk morphogen DIF, suggesting that rblA normally suppresses the DIF response in cells destined for the spore pathway. rblA overexpression during growth leads to G1 arrest, but as growing Dictyostelium are overwhelmingly in G2 phase, rblA does not seem to be important in the normal cell cycle. rblA-null cells show reduced cell size and a premature growth-development transition; the latter appears anomalous but may reflect selection pressures acting on social ameba.
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Affiliation(s)
- Harry MacWilliams
- Biozentrum der Ludwig-Maximilians-Universität, Grosshadernerstrasse 2, 82152 Planegg-Martinsried, Germany.
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Korenjak M, Brehm A. E2F-Rb complexes regulating transcription of genes important for differentiation and development. Curr Opin Genet Dev 2006; 15:520-7. [PMID: 16081278 DOI: 10.1016/j.gde.2005.07.001] [Citation(s) in RCA: 125] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2005] [Accepted: 07/21/2005] [Indexed: 01/22/2023]
Abstract
Inactivation of the retinoblastoma tumour suppressor protein (pRb) is a hallmark of most human cancers. Accordingly, pRb is serving as a paradigm in our quest to understand tumour suppressor function. The role played by pRb and the related 'pocket proteins', p107 and p130, in regulating cell cycle progression has been extensively studied over the past two decades. The function of pRb in regulating transcriptional programmes in differentiating cells is less well understood. Recently, the use of a variety of different cell, animal and plant model systems has allowed us a first glimpse at some of the molecular mechanisms underlying pRb-mediated transcriptional regulation during differentiation and development.
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Affiliation(s)
- Michael Korenjak
- Lehrstuhl für Molekularbiologie, Adolf-Butenandt-Institut, Ludwig-Maximilians-Universität, Schillerstrasse 44, 80336 München, Germany
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Abstract
Rb was the first tumour suppressor identified through human genetic studies. The most significant achievement after almost twenty years since its cloning is the revelation that Rb possesses functions of a transcription regulator. Rb serves as a transducer between the cell cycle machinery and promoter-specific transcription factors. In this capacity, Rb is best known as a repressor of the E2F/DP family of transcription factors, which regulate expression of genes involved in cell proliferation and survival. An equally important aspect of Rb as a transcription regulator is that Rb also activates certain differentiation transcription factors to promote cellular differentiation. The molecular mechanisms behind the repressive effects of Rb on E2Fs have come to light in significant details, while those relating to Rb activation of differentiation transcription factors are much less understood. Finally, it has become clear that there are other aspects to Rb function that are not immediately related to transcription regulation.
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Affiliation(s)
- Liang Zhu
- Department of Developmental and Molecular Biology, and Medicine, The Albert Einstein Comprehensive Cancer Center, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA.
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49
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Abstract
The retinoblastoma protein (pRB) and the pRB-related p107 and p130 comprise the 'pocket protein' family of cell cycle regulators. These proteins are best known for their roles in restraining the G1-S transition through the regulation of E2F-responsive genes. pRB and the p107/p130 pair are required for the repression of distinct sets of genes, potentially due to their selective interactions with E2Fs that are engaged at specific promoter elements. In addition to regulating E2F-responsive genes in a reversible manner, pocket proteins contribute to silencing of such genes in cells that are undergoing senescence or differentiation. Pocket proteins also affect the G1-S transition through E2F-independent mechanisms, such as by inhibiting Cdk2 or by stabilizing p27(Kip1), and they are implicated in the control of G0 exit, the spatial organization of replication, and genomic rereplication. New insights into pocket protein regulation have also been obtained. Kinases previously thought to be crucial to pocket protein phosphorylation have been shown to be redundant, and new modes of phosphorylation and dephosphorylation have been identified. Despite these advances, much remains to be learned about the pocket proteins, particularly with regard to their developmental and tumor suppressor functions. Thus continues the story of the pocket proteins and the cell cycle.
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Affiliation(s)
- David Cobrinik
- Dyson Vision Research Institute and Department of Ophthalmology, Weill Medical College of Cornell University, 1300 York Avenue, LC303, New York, NY 10021, USA.
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Zhou XM, Lin JS, Shi Y, Tian DA, Huang HJ, Zhou HJ, Jin YX. Establishment of a screening system for selection of siRNA target sites directed against hepatitis B virus surface gene. Acta Biochim Biophys Sin (Shanghai) 2005; 37:310-6. [PMID: 15880259 DOI: 10.1111/j.1745-7270.2005.00049.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
To study the inhibitory effects of plasmid-derived small interfering RNA (siRNA) and synthetic siRNA on the expression of the hepatitis B virus surface (HBs) gene, three plasmid-derived siRNAs and one synthetic siRNA that complement the coding region of the HBs gene were prepared. The HBs expression plasmid pHBs-EGFP was also constructed. HeLa cells were co-transfected with pHBs-EGFP and the above siRNAs. The HBs mRNA quantities were measured by reverse-transcription PCR, and the level of HBs-EGFP fusion protein was quantified by fluorescent microscope. The concentrations of the hepatitis B virus surface antigen (HBsAg) derived from the culture supernatant of transfected HepG2.2.15 cells were measured by an enzyme-linked immunosorbent assay (ELISA) kit. The results showed that the three plasmid-derived siRNAs and the synthetic siRNA can effectively reduce the quantities of HBs mRNA and protein. The plasmid-derived siRNA psiRNA1 was found to be the most effective inhibitor of HBs expression. It can inhibit HBs-EGFP expression by 63.3% and suppress HBs mRNA by 75.6%. To further substantiate the above observations, psiRNA1 was transfected into HepG2.2.15 cells (an HBV secreting cell line). The transfections resulted in almost complete blockage of HBsAg production, whereas control vector-transfected cells secreted high levels of HBsAg 7 days post-transfection. In conclusion, our data suggests that RNA interference (RNAi) is an efficient approach for reducing the level of HBs transcripts and proteins and for suppressing HBsAg production.
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Affiliation(s)
- Xiu-Min Zhou
- Institute of Liver Diseases, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
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