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Ma Y, Liu L, Wei Z, Zhu M, Huang L, Wang S, Yi X, Ying F, Zhao S, Cai J, Wang Z, Sun S. Loss of CBX2 causes genomic instability and Wnt activation in high grade serous ovarian carcinoma cells. Mol Carcinog 2023; 62:479-492. [PMID: 36621979 DOI: 10.1002/mc.23500] [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: 09/01/2022] [Revised: 11/24/2022] [Accepted: 12/09/2022] [Indexed: 01/10/2023]
Abstract
High grade serous ovarian carcinoma (HGSOC) is lethal with insidious onset, rapid progression, poor prognosis, and limited treatment options. Polycomb repressor complexes (PRC) 1 and 2 are intimately involved in progression of many types of cancer including HGSOC. Unlike the consistent constitution of PRC2, PRC1 consists of diverse components whose clinical significance in HGSOC are not entirely clear. Here, prognosis-associated PRC1 components were identified through data-mining. CBX2 promoted proliferation and reduced apoptosis of HGSOC cell lines OVCAR4, OVCAR3, and CAOV3. Complete loss of CBX2 by CRISPR-cas9 editing (CBX2KO ) destabilized genome stability with increased spontaneous chromosomal breaks and tendency to polyploidy accompanied by disrupted cell cycle especially stalled G2/M transition and caused severe cell death. Wnt/β-catenin/LEF1/TCF7L1 was activated in surviving OVCAR4-CBX2KO clones to bypass the crisis caused by loss of CBX2. The relieve of TCF7L1 core-promoter region occupied by CBX2 might be one of the possible explanations to TCF7L1 increase in OVCAR4-CBX2KO clones. Subcutaneous tumor model further validated that depletion of CBX2 repressed HGSOC cell line derived tumor growth. High immunohistochemistry score of CBX2 in primary ovarian cancer tissue associated with advanced clinical stage (p = 0.033), poor overall survival (HR = 3.056, 95% CI: 1.024-9.123), and progression free survival (HR = 4.455, 95% CI: 1.513-13.118) in HGSOC. Overall, our results suggested that CBX2 was a promising prognostic factor and therapeutic target in HGSOC.
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Affiliation(s)
- Yujia Ma
- Department of Obstetrics and Gynecology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Lin Liu
- Department of Obstetrics and Gynecology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Zheng Wei
- Department of Obstetrics and Gynecology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Mengna Zhu
- Department of Obstetrics and Gynecology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Lin Huang
- Department of Obstetrics and Gynecology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Shan Wang
- Department of Obstetrics and Gynecology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xiaoqing Yi
- Department of Obstetrics and Gynecology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Feiquan Ying
- Department of Obstetrics and Gynecology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Simei Zhao
- Department of Obstetrics and Gynecology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Jing Cai
- Department of Obstetrics and Gynecology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Zehua Wang
- Department of Obstetrics and Gynecology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Si Sun
- Department of Obstetrics and Gynecology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
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2
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Kim JJ, Kingston RE. Context-specific Polycomb mechanisms in development. Nat Rev Genet 2022; 23:680-695. [PMID: 35681061 PMCID: PMC9933872 DOI: 10.1038/s41576-022-00499-0] [Citation(s) in RCA: 40] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/11/2022] [Indexed: 12/11/2022]
Abstract
Polycomb group (PcG) proteins are crucial chromatin regulators that maintain repression of lineage-inappropriate genes and are therefore required for stable cell fate. Recent advances show that PcG proteins form distinct multi-protein complexes in various cellular environments, such as in early development, adult tissue maintenance and cancer. This surprising compositional diversity provides the basis for mechanistic diversity. Understanding this complexity deepens and refines the principles of PcG complex recruitment, target-gene repression and inheritance of memory. We review how the core molecular mechanism of Polycomb complexes operates in diverse developmental settings and propose that context-dependent changes in composition and mechanism are essential for proper epigenetic regulation in development.
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Affiliation(s)
- Jongmin J. Kim
- Department of Molecular Biology and MGH Research Institute, Massachusetts General Hospital, Boston, MA, USA.,Department of Genetics, Harvard Medical School, Boston, MA, USA
| | - Robert E. Kingston
- Department of Molecular Biology and MGH Research Institute, Massachusetts General Hospital, Boston, MA, USA.,Department of Genetics, Harvard Medical School, Boston, MA, USA.,
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3
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The Role of Polycomb Proteins in Cell Lineage Commitment and Embryonic Development. EPIGENOMES 2022; 6:epigenomes6030023. [PMID: 35997369 PMCID: PMC9397020 DOI: 10.3390/epigenomes6030023] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Revised: 08/09/2022] [Accepted: 08/10/2022] [Indexed: 11/17/2022] Open
Abstract
Embryonic development is a highly intricate and complex process. Different regulatory mechanisms cooperatively dictate the fate of cells as they progress from pluripotent stem cells to terminally differentiated cell types in tissues. A crucial regulator of these processes is the Polycomb Repressive Complex 2 (PRC2). By catalyzing the mono-, di-, and tri-methylation of lysine residues on histone H3 tails (H3K27me3), PRC2 compacts chromatin by cooperating with Polycomb Repressive Complex 1 (PRC1) and represses transcription of target genes. Proteomic and biochemical studies have revealed two variant complexes of PRC2, namely PRC2.1 which consists of the core proteins (EZH2, SUZ12, EED, and RBBP4/7) interacting with one of the Polycomb-like proteins (MTF2, PHF1, PHF19), and EPOP or PALI1/2, and PRC2.2 which contains JARID2 and AEBP2 proteins. MTF2 and JARID2 have been discovered to have crucial roles in directing and recruiting PRC2 to target genes for repression in embryonic stem cells (ESCs). Following these findings, recent work in the field has begun to explore the roles of different PRC2 variant complexes during different stages of embryonic development, by examining molecular phenotypes of PRC2 mutants in both in vitro (2D and 3D differentiation) and in vivo (knock-out mice) assays, analyzed with modern single-cell omics and biochemical assays. In this review, we discuss the latest findings that uncovered the roles of different PRC2 proteins during cell-fate and lineage specification and extrapolate these findings to define a developmental roadmap for different flavors of PRC2 regulation during mammalian embryonic development.
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4
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Piunti A, Shilatifard A. The roles of Polycomb repressive complexes in mammalian development and cancer. Nat Rev Mol Cell Biol 2021; 22:326-345. [PMID: 33723438 DOI: 10.1038/s41580-021-00341-1] [Citation(s) in RCA: 189] [Impact Index Per Article: 63.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/22/2021] [Indexed: 12/14/2022]
Abstract
More than 80 years ago, the first Polycomb-related phenotype was identified in Drosophila melanogaster. Later, a group of diverse genes collectively called Polycomb group (PcG) genes were identified based on common mutant phenotypes. PcG proteins, which are well-conserved in animals, were originally characterized as negative regulators of gene transcription during development and subsequently shown to function in various biological processes; their deregulation is associated with diverse phenotypes in development and in disease, especially cancer. PcG proteins function on chromatin and can form two distinct complexes with different enzymatic activities: Polycomb repressive complex 1 (PRC1) is a histone ubiquitin ligase and PRC2 is a histone methyltransferase. Recent studies have revealed the existence of various mutually exclusive PRC1 and PRC2 variants. In this Review, we discuss new concepts concerning the biochemical and molecular functions of these new PcG complex variants, and how their epigenetic activities are involved in mammalian development and cancer.
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Affiliation(s)
- Andrea Piunti
- Simpson Querrey Institute for Epigenetics, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.,Department of Biochemistry and Molecular Genetics, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Ali Shilatifard
- Simpson Querrey Institute for Epigenetics, Northwestern University Feinberg School of Medicine, Chicago, IL, USA. .,Department of Biochemistry and Molecular Genetics, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.
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5
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Gentile C, Kmita M. Polycomb Repressive Complexes in Hox Gene Regulation: Silencing and Beyond: The Functional Dynamics of Polycomb Repressive Complexes in Hox Gene Regulation. Bioessays 2020; 42:e1900249. [PMID: 32743818 DOI: 10.1002/bies.201900249] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Revised: 06/17/2020] [Indexed: 11/10/2022]
Abstract
The coordinated expression of the Hox gene family encoding transcription factors is critical for proper embryonic development and patterning. Major efforts have thus been dedicated to understanding mechanisms controlling Hox expression. In addition to the temporal and spatial sequential activation of Hox genes, proper embryonic development requires that Hox genes get differentially silenced in a cell-type specific manner as development proceeds. Factors contributing to Hox silencing include the polycomb repressive complexes (PRCs), which control gene expression through epigenetic modifications. This review focuses on PRC-dependent regulation of the Hox genes and is aimed at integrating the growing complexity of PRC functional properties in the context of Hox regulation. In particular, mechanisms underlying PRC binding dynamics as well as a series of studies that have revealed the impact of PRC on the 3D organization of the genome is discussed, which has a significant role on Hox regulation during development.
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Affiliation(s)
- Claudia Gentile
- Genetics and Development Research Unit, Institut de Recherches Cliniques de Montréal, Montréal, Québec, H2W 1R7, Canada.,Department of Experimental Medicine, McGill University, Montreal, Quebec, H4A 3J1, Canada.,Dana-Farber Cancer Institute and Harvard Medical School, Boston, MA, 02215, USA
| | - Marie Kmita
- Genetics and Development Research Unit, Institut de Recherches Cliniques de Montréal, Montréal, Québec, H2W 1R7, Canada.,Department of Experimental Medicine, McGill University, Montreal, Quebec, H4A 3J1, Canada.,Département de Médecine, Université de Montréal, Montréal, Quebec, H3C 3J7, Canada
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6
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Stamoulis G, Garieri M, Makrythanasis P, Letourneau A, Guipponi M, Panousis N, Sloan-Béna F, Falconnet E, Ribaux P, Borel C, Santoni F, Antonarakis SE. Single cell transcriptome in aneuploidies reveals mechanisms of gene dosage imbalance. Nat Commun 2019; 10:4495. [PMID: 31582743 PMCID: PMC6776538 DOI: 10.1038/s41467-019-12273-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Accepted: 08/16/2019] [Indexed: 12/13/2022] Open
Abstract
Aneuploidy is a major source of gene dosage imbalance due to copy number alterations (CNA), and viable human trisomies are model disorders of altered gene expression. We study gene and allele-specific expression (ASE) of 9668 single-cell fibroblasts from trisomy 21 (T21) discordant twins and from mosaic T21, T18, T13 and T8. We examine 928 single cells with deep scRNAseq. Expected and observed overexpression of trisomic genes in trisomic vs. diploid bulk RNAseq is not detectable in trisomic vs. diploid single cells. Instead, for trisomic genes with low-to-average expression, their altered gene dosage is mainly due to the higher fraction of trisomic cells simultaneously expressing these genes, in agreement with a stochastic 2-state burst-like model of transcription. These results, confirmed in a further analysis of 8740 single fibroblasts with shallow scRNAseq, suggest that the specific transcriptional profile of each gene contributes to the phenotypic variability of trisomies. We propose an improved model to understand the effects of CNA and, generally, of gene regulation on gene dosage imbalance.
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Affiliation(s)
- Georgios Stamoulis
- Department of Genetic Medicine and Development, University of Geneva Medical School, 1211 Geneva 4, Geneva, Switzerland
| | - Marco Garieri
- Department of Genetic Medicine and Development, University of Geneva Medical School, 1211 Geneva 4, Geneva, Switzerland
| | - Periklis Makrythanasis
- Department of Genetic Medicine and Development, University of Geneva Medical School, 1211 Geneva 4, Geneva, Switzerland
- Biomedical Research Institute Academy of Athens, Athens, Greece
| | - Audrey Letourneau
- Department of Genetic Medicine and Development, University of Geneva Medical School, 1211 Geneva 4, Geneva, Switzerland
| | - Michel Guipponi
- Geneva University Hospitals, Service of Genetic Medicine, 1211 Geneva 4, Geneva, Switzerland
| | - Nikolaos Panousis
- Department of Genetic Medicine and Development, University of Geneva Medical School, 1211 Geneva 4, Geneva, Switzerland
| | - Frédérique Sloan-Béna
- Geneva University Hospitals, Service of Genetic Medicine, 1211 Geneva 4, Geneva, Switzerland
| | - Emilie Falconnet
- Department of Genetic Medicine and Development, University of Geneva Medical School, 1211 Geneva 4, Geneva, Switzerland
| | - Pascale Ribaux
- Department of Genetic Medicine and Development, University of Geneva Medical School, 1211 Geneva 4, Geneva, Switzerland
| | - Christelle Borel
- Department of Genetic Medicine and Development, University of Geneva Medical School, 1211 Geneva 4, Geneva, Switzerland
| | - Federico Santoni
- Service of Endocrinology, Diabetes and Metabolism, University Hospital of Lausanne - CHUV, Lausanne, 1011, Switzerland.
| | - Stylianos E Antonarakis
- Department of Genetic Medicine and Development, University of Geneva Medical School, 1211 Geneva 4, Geneva, Switzerland.
- Geneva University Hospitals, Service of Genetic Medicine, 1211 Geneva 4, Geneva, Switzerland.
- iGE3 Institute of Genetics and Genomics of Geneva, University of Geneva, 1211 Geneva 4, Geneva, Switzerland.
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7
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Hu T, Kitano A, Luu V, Dawson B, Hoegenauer KA, Lee BH, Nakada D. Bmi1 Suppresses Adipogenesis in the Hematopoietic Stem Cell Niche. Stem Cell Reports 2019; 13:545-558. [PMID: 31257132 PMCID: PMC6739622 DOI: 10.1016/j.stemcr.2019.05.027] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Revised: 05/28/2019] [Accepted: 05/29/2019] [Indexed: 12/11/2022] Open
Abstract
Bone marrow stromal cells (BMSCs) that express high levels of stem cell factor (SCF) and CXC chemokine ligand 12 (CXCL12) are one crucial component of the hematopoietic stem cell (HSC) niche. While the secreted factors produced by BMSCs to support HSCs have been well described, little is known regarding the transcriptional regulators controlling the cell fate of BMSCs and thus indirectly maintaining HSCs. BMI1 is a polycomb group protein that regulates HSCs both cell intrinsically and extrinsically, but it is unknown in which cell type and how BMI1 functions to maintain HSCs extrinsically. Here we show that Bmi1 maintains HSCs by preventing adipogenic differentiation of BMSCs. Bmi1 is highly expressed in BMSCs but becomes downregulated upon adipogenic differentiation and during aging. Deleting Bmi1 from BMSCs increased marrow adipocytes, induced HSC quiescence and depletion, and impaired hematopoiesis. We found that BMI1 repressed multiple developmental programs in BMSCs by safeguarding the repressive epigenetic marks histone H2A ubiquitylation and H3 lysine 27 trimethylation. We identified a novel adipogenic program governed by Pax3, which BMI1 repressed in BMSCs. Our results establish Bmi1 as a critical regulator of BMSC cell fate that suppresses marrow adipogenesis to create a supportive niche for HSCs.
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Affiliation(s)
- Tianyuan Hu
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Ayumi Kitano
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Victor Luu
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Brian Dawson
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Kevin A Hoegenauer
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Brendan H Lee
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Daisuke Nakada
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA.
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8
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Chen G, Zhang Y, Yu S, Sun W, Miao D. Bmi1 Overexpression in Mesenchymal Stem Cells Exerts Antiaging and Antiosteoporosis Effects by Inactivating p16/p19 Signaling and Inhibiting Oxidative Stress. Stem Cells 2019; 37:1200-1211. [PMID: 30895687 PMCID: PMC6851636 DOI: 10.1002/stem.3007] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2019] [Revised: 02/24/2019] [Accepted: 03/03/2019] [Indexed: 01/19/2023]
Abstract
We previously demonstrated that Bmi1 deficiency leads to osteoporosis phenotype by inhibiting the proliferation and osteogenic differentiation of bone marrow mesenchymal stem cells (MSCs), but it is unclear whether overexpression of Bmi1 in MSCs stimulates skeletal development and rescues Bmi1 deficiency-induced osteoporosis. To answer this question, we constructed transgenic mice (Bmi1Tg ) that overexpressed Bmi1 driven by the Prx1 gene and analyzed their skeletal phenotype differences with that of wild-type littermates. We then hybridized Bmi1Tg to Bmi1-/- mice to generate Bmi1-/- mice overexpressing Bmi1 in MSCs and compared their skeletal phenotypes with those of Bmi1-/- and wild-type mice using imaging, histopathological, immunohistochemical, histomorphometric, cellular, and molecular methods. Bmi1Tg mice exhibited enhanced bone growth and osteoblast formation, including the augmentation of bone size, cortical and trabecular volume, number of osteoblasts, alkaline phosphatase (ALP)-positive and type I collagen-positive areas, number of total colony forming unit fibroblasts (CFU-f) and ALP+ CFU-f, and osteogenic gene expression levels. Consistently, MSC overexpressing Bmi1 in the Bmi1-/- background not only largely reversed Bmi1 systemic deficiency-induced skeletal growth retardation and osteoporosis, but also partially reversed Bmi1 deficiency-induced systemic growth retardation and premature aging. To further explore the mechanism of action of MSCs overexpressing Bmi1 in antiosteoporosis and antiaging, we examined changes in oxidative stress and expression levels of p16 and p19. Our results showed that overexpression of Bmi1 in MSCs inhibited oxidative stress and downregulated p16 and p19. Taken together, the results of this study indicate that overexpression of Bmi1 in MSCs exerts antiaging and antiosteoporosis effects by inactivating p16/p19 signaling and inhibiting oxidative stress. Stem Cells 2019;37:1200-1211.
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Affiliation(s)
- Guangpei Chen
- Department of Human Anatomy, Guangzhou University of Chinese Medicine, Guangzhou, People's Republic of China.,The Research Center for Bone and Stem Cells, Nanjing Medical University, Nanjing, People's Republic of China
| | - Ying Zhang
- The Research Center for Bone and Stem Cells, Nanjing Medical University, Nanjing, People's Republic of China.,Department of Anatomy, Histology, and Embryology, Suzhou Health and Technology College, Suzhou, People's Republic of China
| | - Shuxiang Yu
- The Research Center for Bone and Stem Cells, Nanjing Medical University, Nanjing, People's Republic of China
| | - Wen Sun
- The Research Center for Bone and Stem Cells, Nanjing Medical University, Nanjing, People's Republic of China
| | - Dengshun Miao
- The Research Center for Bone and Stem Cells, Nanjing Medical University, Nanjing, People's Republic of China.,The Research Center for Aging, Affiliated Friendship Plastic Surgery Hospital of Nanjing Medical University, Nanjing Medical University, Nanjing, People's Republic of China
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9
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Katoh-Fukui Y, Baba T, Sato T, Otake H, Nagakui-Noguchi Y, Shindo M, Suyama M, Ohkawa Y, Tsumura H, Morohashi KI, Fukami M. Mouse polycomb group gene Cbx2 promotes osteoblastic but suppresses adipogenic differentiation in postnatal long bones. Bone 2019; 120:219-231. [PMID: 30389610 DOI: 10.1016/j.bone.2018.10.021] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Revised: 10/19/2018] [Accepted: 10/19/2018] [Indexed: 12/29/2022]
Abstract
A set of key developmental genes is essential for skeletal growth from multipotent progenitor cells at weaning. Polycomb group proteins, which regulate such genes contributes to the cell lineage commitment and subsequent differentiation via epigenetic chromatin modification and remodeling. However, it is unclear which cell lineage and gene sets are targeted by polycomb proteins during skeletal growth. We now report that mice deficient in a polycomb group gene Cbx2cterm/cterm exhibited skeletal hypoplasia in the tibia, femur, and cranium. Long bone cavities in these mice contained fewer multipotent mesenchymal stromal cells. RNA-sequencing of bone marrow cells showed downregulation and upregulation of osteoblastic and adipogenic genes, respectively. Furthermore, the expression levels of genes specifically expressed in B-cell precursors were decreased. Forced expression of Cbx2 in Cbx2cterm/cterm bone marrow stromal cell recovered fibroblastic colony formation and suppressed adipogenic differentiation. Collectively, our results suggest that Cbx2 controls the maintenance and adipogenic differentiation of mesenchymal stromal cells in the bone marrow.
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Affiliation(s)
- Yuko Katoh-Fukui
- Department of Molecular Endocrinology, National Research Institute of Child Health and Development, Tokyo 157-8535, Japan.
| | - Takashi Baba
- Department of Molecular Biology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan; Department of Systems Life Sciences, Graduate School of Systems Life Sciences, Kyushu University, Fukuoka, Japan
| | - Tetsuya Sato
- Department of Systems Life Sciences, Graduate School of Systems Life Sciences, Kyushu University, Fukuoka, Japan; Division of Bioinformatics, Kyushu University, Fukuoka, Japan; AMED-CREST, Japan Agency for Medical Research and Development, Fukuoka, Japan
| | - Hiroyuki Otake
- Department of Molecular Biology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | | | - Miyuki Shindo
- Department of Experimental Animals, National Research Institute of Child Health and Development, Tokyo, Japan
| | - Mikita Suyama
- Department of Systems Life Sciences, Graduate School of Systems Life Sciences, Kyushu University, Fukuoka, Japan; Division of Bioinformatics, Kyushu University, Fukuoka, Japan; AMED-CREST, Japan Agency for Medical Research and Development, Fukuoka, Japan
| | - Yasuyuki Ohkawa
- Department of Systems Life Sciences, Graduate School of Systems Life Sciences, Kyushu University, Fukuoka, Japan; AMED-CREST, Japan Agency for Medical Research and Development, Fukuoka, Japan; Research Center for Transomics Medicine, Medical Institute of Bioregulation, Kyushu University, Fukuoka, Japan
| | - Hideki Tsumura
- Department of Experimental Animals, National Research Institute of Child Health and Development, Tokyo, Japan
| | - Ken-Ichirou Morohashi
- Department of Molecular Biology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan; Department of Systems Life Sciences, Graduate School of Systems Life Sciences, Kyushu University, Fukuoka, Japan
| | - Maki Fukami
- Department of Molecular Endocrinology, National Research Institute of Child Health and Development, Tokyo 157-8535, Japan
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10
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Yoshioka T, Fukuda A, Araki O, Ogawa S, Hanyu Y, Matsumoto Y, Yamaga Y, Nakanishi Y, Kawada K, Sakai Y, Chiba T, Seno H. Bmi1 marks gastric stem cells located in the isthmus in mice. J Pathol 2019; 248:179-190. [DOI: 10.1002/path.5244] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2018] [Revised: 12/23/2018] [Accepted: 01/21/2019] [Indexed: 01/10/2023]
Affiliation(s)
- Takuto Yoshioka
- Department of Gastroenterology and HepatologyKyoto University Graduate School of Medicine Kyoto Japan
| | - Akihisa Fukuda
- Department of Gastroenterology and HepatologyKyoto University Graduate School of Medicine Kyoto Japan
| | - Osamu Araki
- Department of Gastroenterology and HepatologyKyoto University Graduate School of Medicine Kyoto Japan
| | - Satoshi Ogawa
- Department of Gastroenterology and HepatologyKyoto University Graduate School of Medicine Kyoto Japan
| | - Yuta Hanyu
- Department of Gastroenterology and HepatologyKyoto University Graduate School of Medicine Kyoto Japan
| | - Yoshihide Matsumoto
- Department of Gastroenterology and HepatologyKyoto University Graduate School of Medicine Kyoto Japan
| | - Yuichi Yamaga
- Department of Gastroenterology and HepatologyKyoto University Graduate School of Medicine Kyoto Japan
| | - Yuki Nakanishi
- Department of Gastroenterology and HepatologyKyoto University Graduate School of Medicine Kyoto Japan
| | - Kenji Kawada
- Department of SurgeryKyoto University Graduate School of Medicine Kyoto Japan
| | - Yoshiharu Sakai
- Department of SurgeryKyoto University Graduate School of Medicine Kyoto Japan
| | - Tsutomu Chiba
- Department of Gastroenterology and HepatologyKyoto University Graduate School of Medicine Kyoto Japan
- Kansai Electric Power Hospital Osaka Japan
| | - Hiroshi Seno
- Department of Gastroenterology and HepatologyKyoto University Graduate School of Medicine Kyoto Japan
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11
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Young M, Selleri L, Capellini TD. Genetics of scapula and pelvis development: An evolutionary perspective. Curr Top Dev Biol 2019; 132:311-349. [PMID: 30797513 PMCID: PMC6430119 DOI: 10.1016/bs.ctdb.2018.12.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
In tetrapods, the scapular and pelvic girdles perform the important function of anchoring the limbs to the trunk of the body and facilitating the movement of each appendage. This shared function, however, is one of relatively few similarities between the scapula and pelvis, which have significantly different morphologies, evolutionary histories, embryonic origins, and underlying genetic pathways. The scapula evolved in jawless fish prior to the pelvis, and its embryonic development is unique among bones in that it is derived from multiple progenitor cell populations, including the dermomyotome, somatopleure, and neural crest. Conversely, the pelvis evolved several million years later in jawed fish, and it develops from an embryonic somatopleuric cell population. The genetic networks controlling the formation of the pelvis and scapula also share similarities and differences, with a number of genes shaping only one or the other, while other gene products such as PBX transcription factors act as hierarchical developmental regulators of both girdle structures. Here, we provide a detailed review of the cellular processes and genetic networks underlying pelvis and scapula formation in tetrapods, while also highlighting unanswered questions about girdle evolution and development.
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Affiliation(s)
- Mariel Young
- Department of Human Evolutionary Biology, Harvard University, Cambridge, MA, United States
| | - Licia Selleri
- Program in Craniofacial Biology, Department of Orofacial Sciences, Eli and Edythe Broad Center of Regeneration Medicine & Stem Cell Research, University of California, Institute of Human Genetics, San Francisco, CA, United States; Program in Craniofacial Biology, Department of Anatomy, Eli and Edythe Broad Center of Regeneration Medicine & Stem Cell Research, University of California, Institute of Human Genetics, San Francisco, CA, United States.
| | - Terence D Capellini
- Department of Human Evolutionary Biology, Harvard University, Cambridge, MA, United States; Broad Institute of Harvard and MIT, Cambridge, MA, United States.
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12
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Brocal J, De Decker S, José-López R, Manzanilla EG, Penderis J, Stalin C, Bertram S, Schoenebeck JJ, Rusbridge C, Fitzpatrick N, Gutierrez-Quintana R. C7 vertebra homeotic transformation in domestic dogs - are Pug dogs breaking mammalian evolutionary constraints? J Anat 2018; 233:255-265. [PMID: 29761492 DOI: 10.1111/joa.12822] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/11/2018] [Indexed: 12/20/2022] Open
Abstract
The number of cervical vertebrae in mammals is almost constant at seven, regardless of their neck length, implying that there is selection against variation in this number. Homebox (Hox) genes are involved in this evolutionary mammalian conservation, and homeotic transformation of cervical into thoracic vertebrae (cervical ribs) is a common phenotypic abnormality when Hox gene expression is altered. This relatively benign phenotypic change can be associated with fatal traits in humans. Mutations in genes upstream of Hox, inbreeding and stressors during organogenesis can also cause cervical ribs. The aim of this study was to describe the prevalence of cervical ribs in a large group of domestic dogs of different breeds, and explore a possible relation with other congenital vertebral malformations (CVMs) in the breed with the highest prevalence of cervical ribs. By phenotyping we hoped to give clues as to the underlying genetic causes. Twenty computed tomography studies from at least two breeds belonging to each of the nine groups recognized by the Federation Cynologique Internationale, including all the brachycephalic 'screw-tailed' breeds that are known to be overrepresented for CVMs, were reviewed. The Pug dog was more affected by cervical ribs than any other breed (46%; P < 0.001), and was selected for further analysis. No association was found between the presence of cervical ribs and vertebral body formation defect, bifid spinous process, caudal articular process hypoplasia/aplasia and an abnormal sacrum, which may infer they have a different aetiopathogenesis. However, Pug dogs with cervical ribs were more likely to have a transitional thoraco-lumbar vertebra (P = 0.041) and a pre-sacral vertebral count of 26 (P < 0.001). Higher C7/T1 dorsal spinous processes ratios were associated with the presence of cervical ribs (P < 0.001), supporting this is a true homeotic transformation. Relaxation of the stabilizing selection has likely occurred, and the Pug dog appears to be a good naturally occurring model to further investigate the aetiology of cervical ribs, other congenital vertebral anomalies and numerical alterations.
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Affiliation(s)
- J Brocal
- School of Veterinary Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - S De Decker
- Department of Veterinary Clinical Science and Services, The Royal Veterinary College, University of London, North Mymms, Hertfordshire, UK
| | - R José-López
- School of Veterinary Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - E G Manzanilla
- Teagasc Animal and Grassland Research and Innovation Centre, Moorepark, Fermoy, Co. Cork, Ireland
| | - J Penderis
- Vet-Extra Neurology, Broadleys Veterinary Hospital, Stirling, UK
| | - C Stalin
- School of Veterinary Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - S Bertram
- Department of Veterinary Clinical Science and Services, The Royal Veterinary College, University of London, North Mymms, Hertfordshire, UK
| | - J J Schoenebeck
- Royal (Dick) School of Veterinary Studies and Roslin Institute, University of Edinburgh, Easter Bush, Midlothian, UK
| | - C Rusbridge
- Fitzpatrick Referrals, Eashing, Surrey, UK.,School of Veterinary Medicine, Faculty of Health & Medical Sciences, University of Surrey, Guildford, Surrey, UK
| | | | - R Gutierrez-Quintana
- School of Veterinary Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
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13
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Villamil CI. Phenotypic integration of the cervical vertebrae in the Hominoidea (Primates). Evolution 2018; 72:490-517. [DOI: 10.1111/evo.13433] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Revised: 01/11/2018] [Accepted: 01/12/2018] [Indexed: 12/30/2022]
Affiliation(s)
- Catalina I. Villamil
- Department of Anthropology; Dickinson College; P.O. Box 1773 Carlisle Pennsylvania 17013
- Center for the Study of Human Origins, Department of Anthropology; New York University; 25 Waverly Place New York New York 10003
- New York Consortium in Evolutionary Primatology; New York New York 10024
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14
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From Flies to Mice: The Emerging Role of Non-Canonical PRC1 Members in Mammalian Development. EPIGENOMES 2018. [DOI: 10.3390/epigenomes2010004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
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15
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Zhou X, Dai X, Wu X, Ji J, Karaplis A, Goltzman D, Yang X, Miao D. Overexpression of Bmi1 in Lymphocytes Stimulates Skeletogenesis by Improving the Osteogenic Microenvironment. Sci Rep 2016; 6:29171. [PMID: 27373231 PMCID: PMC4931581 DOI: 10.1038/srep29171] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Accepted: 06/15/2016] [Indexed: 12/13/2022] Open
Abstract
To investigate whether overexpression of Bmi1 in lymphocytes can stimulate skeletogenesis by improving the osteogenic microenvironment, we examined the skeletal phenotype of EμBmi1 transgenic mice with overexpression of Bmi1 in lymphocytes. The size of the skeleton, trabecular bone volume and osteoblast number, indices of proliferation and differentiation of bone marrow mesenchymal stem cells (BM-MSCs) were increased significantly, ROS levels were reduced and antioxidative capacity was enhanced in EμBmi1 mice compared to WT mice. In PTHrP1-84 knockin (Pthrp(KI/KI)) mice, the expression levels of Bmi1 are reduced and potentially can mediate the premature osteoporosis observed. We therefore generated a Pthrp(KI/KI) mice overexpressing Bmi1 in lymphocytes and compared them with Pthrp(KI/KI) and WT littermates. Overexpression of Bmi1 in Pthrp(KI/KI) mice resulted in a longer lifespan, increased body weight and improvement in skeletal growth and parameters of osteoblastic bone formation with reduced ROS levels and DNA damage response parameters. Our results demonstrate that overexpression of Bmi1 in lymphocytes can stimulate osteogenesis in vivo and partially rescue defects in skeletal growth and osteogenesis in Pthrp(KI/KI) mice. These studies therefore indicate that overexpression of Bmi1 in lymphocytes can stimulate skeletogenesis by inhibiting oxidative stress and improving the osteogenic microenvironment.
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Affiliation(s)
- Xichao Zhou
- Department of Orthopedics, The First Affiliated Hospital of Soochow University, Suzhou, China
- The State Key Laboratory of Reproductive Medicine, the Research Center for Bone and Stem Cells, Department of Anatomy, Histology and Embryology, Nanjing Medical University, Nanjing, China
| | - Xiuliang Dai
- The State Key Laboratory of Reproductive Medicine, the Research Center for Bone and Stem Cells, Department of Anatomy, Histology and Embryology, Nanjing Medical University, Nanjing, China
| | - Xuan Wu
- The State Key Laboratory of Reproductive Medicine, the Research Center for Bone and Stem Cells, Department of Anatomy, Histology and Embryology, Nanjing Medical University, Nanjing, China
| | - Ji Ji
- The State Key Laboratory of Reproductive Medicine, the Research Center for Bone and Stem Cells, Department of Anatomy, Histology and Embryology, Nanjing Medical University, Nanjing, China
- Department of Fundamentals of Nursing, School of Nursing, Nanjing Medical University, Nanjing, China
| | - Andrew Karaplis
- The Department of Medicine, McGill University, Montreal, Canada
| | - David Goltzman
- The Department of Medicine, McGill University, Montreal, Canada
| | - Xiangjiao Yang
- The Department of Medicine, McGill University, Montreal, Canada
- Rosalind & Morris Goodman Cancer Research Center, Department of Biochemistry, McGill University, Montreal, Quebec, Canada
| | - Dengshun Miao
- The State Key Laboratory of Reproductive Medicine, the Research Center for Bone and Stem Cells, Department of Anatomy, Histology and Embryology, Nanjing Medical University, Nanjing, China
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16
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Harikumar A, Meshorer E. Chromatin remodeling and bivalent histone modifications in embryonic stem cells. EMBO Rep 2015; 16:1609-19. [PMID: 26553936 DOI: 10.15252/embr.201541011] [Citation(s) in RCA: 158] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Accepted: 10/05/2015] [Indexed: 11/09/2022] Open
Abstract
Pluripotent embryonic stem cells (ESCs) are characterized by distinct epigenetic features including a relative enrichment of histone modifications related to active chromatin. Among these is tri-methylation of lysine 4 on histone H3 (H3K4me3). Several thousands of the H3K4me3-enriched promoters in pluripotent cells also contain a repressive histone mark, namely H3K27me3, a situation referred to as "bivalency". While bivalent promoters are not unique to pluripotent cells, they are relatively enriched in these cell types, largely marking developmental and lineage-specific genes which are silent but poised for immediate action. The H3K4me3 and H3K27me3 modifications are catalyzed by lysine methyltransferases which are usually found within, although not entirely limited to, the Trithorax group (TrxG) and Polycomb group (PcG) protein complexes, respectively, but these do not provide selective bivalent specificity. Recent studies highlight the family of ATP-dependent chromatin remodeling proteins as regulators of bivalent domains. Here, we discuss bivalency in general, describe the machineries that catalyze bivalent chromatin domains, and portray the emerging connection between bivalency and the action of different families of chromatin remodelers, namely INO80, esBAF, and NuRD, in pluripotent cells. We posit that chromatin remodeling proteins may enable "bivalent specificity", often selectively acting on, or selectively depleted from, bivalent domains.
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Affiliation(s)
- Arigela Harikumar
- Department of Genetics, Institute of Life Sciences and The Edmond and Lily Safra Center for Brain Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Eran Meshorer
- Department of Genetics, Institute of Life Sciences and The Edmond and Lily Safra Center for Brain Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
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17
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Chen LL, Zhao JC. Functional analysis of long noncoding RNAs in development and disease. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 825:129-58. [PMID: 25201105 DOI: 10.1007/978-1-4939-1221-6_4] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Once viewed as part of the "dark matter" of genome, long noncoding RNAs (lncRNAs), which are mRNA-like but lack open reading frames, have emerged as an integral part of the mammalian transcriptome. Recent work demonstrated that lncRNAs play multiple structural and functional roles, and their analysis has become a new frontier in biomedical research. In this chapter, we provide an overview of different lncRNA families, describe methodologies available to study lncRNA-protein and lncRNA-DNA interactions systematically, and use well-studied lncRNAs as examples to illustrate their functional importance during normal development and in disease states.
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Affiliation(s)
- Ling-Ling Chen
- State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200031, China,
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18
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Aloia L, Di Stefano B, Di Croce L. Polycomb complexes in stem cells and embryonic development. Development 2013; 140:2525-34. [PMID: 23715546 DOI: 10.1242/dev.091553] [Citation(s) in RCA: 228] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Polycomb group (PcG) proteins are epigenetic modifiers involved in controlling gene repression. Organized within multiprotein complexes, they regulate developmental genes in multiple cell types and tissue contexts, including embryonic and adult stem cells, and are essential for cell fate transitions and proper development. Here, we summarize recent breakthroughs that have revealed the diversity of PcG complexes acting in different cell types and genomic contexts. Intriguingly, it appears that particular PcG proteins have specific functions in embryonic development, in pluripotent stem cells and in reprogramming somatic cells into a pluripotent-like state. Finally, we highlight recent results from analyzing PcG protein functions in multipotent stem cells, such as neural, hematopoietic and epidermal stem cells.
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Affiliation(s)
- Luigi Aloia
- Centre for Genomic Regulation (CRG), and UPF, Dr Aiguader 88, 08003 Barcelona,Spain
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19
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Pan X, Papasani M, Hao Y, Calamito M, Wei F, Quinn Iii WJ, Basu A, Wang J, Hodawadekar S, Zaprazna K, Liu H, Shi Y, Allman D, Cancro M, Atchison ML. YY1 controls Igκ repertoire and B-cell development, and localizes with condensin on the Igκ locus. EMBO J 2013; 32:1168-82. [PMID: 23531880 DOI: 10.1038/emboj.2013.66] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2012] [Accepted: 02/11/2013] [Indexed: 12/25/2022] Open
Abstract
Conditional knock-out (KO) of Polycomb Group (PcG) protein YY1 results in pro-B cell arrest and reduced immunoglobulin locus contraction needed for distal variable gene rearrangement. The mechanisms that control these crucial functions are unknown. We deleted the 25 amino-acid YY1 REPO domain necessary for YY1 PcG function, and used this mutant (YY1ΔREPO), to transduce bone marrow from YY1 conditional KO mice. While wild-type YY1 rescued B-cell development, YY1ΔREPO failed to rescue the B-cell lineage yielding reduced numbers of B lineage cells. Although the IgH rearrangement pattern was normal, there was a selective impact at the Igκ locus that showed a dramatic skewing of the expressed Igκ repertoire. We found that the REPO domain interacts with proteins from the condensin and cohesin complexes, and that YY1, EZH2 and condensin proteins co-localize at numerous sites across the Ig kappa locus. Knock-down of a condensin subunit protein or YY1 reduced rearrangement of Igκ Vκ genes suggesting a direct role for YY1-condensin complexes in Igκ locus structure and rearrangement.
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Affiliation(s)
- Xuan Pan
- Department of Animal Biology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA
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20
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21
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Golden MG, Dasen JS. Polycomb repressive complex 1 activities determine the columnar organization of motor neurons. Genes Dev 2012; 26:2236-50. [PMID: 23028147 DOI: 10.1101/gad.199133.112] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Polycomb repressive complexes (PRCs) establish and maintain gene repression through chromatin modifications, but their specific roles in cell fate determination events are poorly understood. Here we show an essential role for the PRC1 component Bmi1 in motor neuron (MN) subtype differentiation through dose-dependent effects on Hox gene expression. While Bmi1 is dispensable for generating MNs as a class, it has an essential role in specifying and determining the position of Hox-dependent MN columnar and pool subtypes. These actions are mediated through limiting anterior Hox expression boundaries, functions deployed in post-mitotic MNs, temporally downstream from morphogen gradients. Within the HoxC gene cluster, we found a progressive depletion of PRC-associated marks from rostral to caudal levels of the spinal cord, corresponding to major demarcations of MN subtypes. Selective ablation of Bmi1 elicits a derepression of more posterior Hox genes, leading to a switch in MN fates. Unexpectedly, Hox patterns and MN fates appear to be sensitive to absolute PRC1 activity levels; while reducing Bmi1 switches forelimb lateral motor column (LMC) MNs to a thoracic preganglionic (PGC) identity, elevating Bmi1 expression at thoracic levels converts PGC to LMC MNs. These results suggest that graded PRC1 activities are essential in determining MN topographic organization.
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Affiliation(s)
- Molly G Golden
- Department of Physiology and Neuroscience, Smilow Neuroscience Program, Howard Hughes Medical Institute, New York University School of Medicine, New York, New York 10016, USA
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22
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Abstract
Polycomb group proteins have long been linked to the occurrence of different forms of cancer. Polycomb proteins form at least two distinct complexes, the Polycomb-repressive complexes 1 and 2 (PRC1 and PRC2). Some of the PRC complex subunits have been found to be overexpressed in a variety of different tumors. Epigenetic perturbations are likely to be the cause for transcriptional misregulation of tumor suppressor genes and of certain cell fates. It is especially critical for stem cells that their potential to self-renewal and to differentiate is tightly controlled and properly orchestrated. Misregulation of Polycomb protein levels often leads to either a block or unscheduled activation of developmental pathways, thereby enhancing the proliferation capability of a cell. The consequences of this misregulation have been linked to the establishment of cancer stem cells, which can produce tumors through a combination of increased self-renewal and the lack of complete cellular differentiation. Cancer stem cells are believed to persist within tumors and to elicit relapse and metastasis. In this review, we recapitulate the roles of Polycomb proteins in stem cell biology, and the impact their misregulation can have on cancer.
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Affiliation(s)
- H Richly
- Department of Differentiation and Cancer, Centre de Regulació Genòmica (CRG), Universitat Pompeu Fabra, Barcelona, Spain
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23
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Bots J, Wijnaendts LCD, Delen S, Van Dongen S, Heikinheimo K, Galis F. Analysis of cervical ribs in a series of human fetuses. J Anat 2011; 219:403-9. [PMID: 21689099 DOI: 10.1111/j.1469-7580.2011.01400.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
In humans, an increasing body of evidence has linked the frequency of cervical ribs to stillbirths, other malformations and early childhood cancers. However, the frequency of cervical ribs in a putatively healthy fetal population is not sufficiently known to assess the actual medical risks of these prenatal findings. We therefore analyzed the presence of skeletal anomalies in a series of 199 electively aborted fetuses, which were whole-mount stained with alizarin red specific for skeletal tissues. Results show that approximately 40% of the fetuses had cervical ribs, even though external congenital abnormalities such as craniofacial and limb defects were absent. A literature overview indicates that the observed frequency of cervical ribs is comparable to results previously obtained for deceased fetuses with no or minor congenital anomalies, and higher than expected for healthy fetuses. This unexpected result can probably in part be explained by a higher detection rate of small cervical ribs when using alizarin red staining instead of radiographs. Additionally, studies in the literature suggest that the size of a cervical rib may indicate the severity of abnormalities, but this possibility requires further research. Anomalies of the axial skeleton are known to be caused by a disturbance of early development, which alters Hox gene expression, but in this study the origin of the stress could not be verified as maternal medical data were not available. The co-occurrence of rudimentary or absent 12th ribs in 23.6% of the cases with cervical ribs indicates that in approximately 8% of the fetuses a homeotic shift occurred over a larger part of the vertebral column. This suggests that the expression of multiple Hox genes may have been affected in these fetuses. Together, the high incidence of cervical ribs and also their co-occurrence with rudimentary or absent 12th ribs suggests that there may have been a disturbance of early development such that the studied fetuses are probably not informative about the general population. Future studies determining the frequency of cervical ribs in a more healthy fetal population are therefore needed to evaluate their potential as an indicator of medical risks.
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Affiliation(s)
- Jessica Bots
- Evolutionary Ecology Group, Department of Biology, University of Antwerp, Antwerp, Belgium.
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24
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Abstract
Controlling cell fate-determining gene expression is key to stem cell differentiation, tissue regeneration, and cancer therapy. To date, custom-built transcription factors recognize the information encoded in specific DNA sequences. Chromatin proteins undergo covalent modifications and form complexes that encode a second layer of information that determines proximal gene activity. Here, we employ a novel gene-targeting approach that exploits a specific chromatin modification to reactivate silenced loci in human cells. We used the human Polycomb chromatin protein and homologues from other species to construct modular synthetic transcription factors, called Pc-TFs, that recognize the repressive trimethyl-histone H3 lysine 27 (H3K27me3) signal and switch silenced genes to an active state. Pc-TF expression in U2OS osteosarcoma cells leads to increased transcription of the senescence locus CDKN2A (p16) and other loci in a chromodomain- and activation module-dependent manner, a switch to a senescence phenotype, and reduced cell proliferation. These results indicate that silenced developmental regulators can be reactivated by a synthetic transcription factor that interacts with chromatin rather than DNA, resulting in an altered cell state. As such, our work extends the flexibility of transcription factor engineering and is the first example of chromatin-mediated synthetic transcription factor targeting.
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Affiliation(s)
- Karmella A Haynes
- Department of Systems Biology, Harvard Medical School, Boston, Massachusetts 02115, USA
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25
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Breaking evolutionary and pleiotropic constraints in mammals: On sloths, manatees and homeotic mutations. EvoDevo 2011; 2:11. [PMID: 21548920 PMCID: PMC3120709 DOI: 10.1186/2041-9139-2-11] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2010] [Accepted: 05/06/2011] [Indexed: 01/25/2023] Open
Abstract
Background Mammals as a rule have seven cervical vertebrae, except for sloths and manatees. Bateson proposed that the change in the number of cervical vertebrae in sloths is due to homeotic transformations. A recent hypothesis proposes that the number of cervical vertebrae in sloths is unchanged and that instead the derived pattern is due to abnormal primaxial/abaxial patterning. Results We test the detailed predictions derived from both hypotheses for the skeletal patterns in sloths and manatees for both hypotheses. We find strong support for Bateson's homeosis hypothesis. The observed vertebral and rib patterns cannot be explained by changes in primaxial/abaxial patterning. Vertebral patterns in sloths and manatees are similar to those in mice and humans with abnormal numbers of cervical vertebrae: incomplete and asymmetric homeotic transformations are common and associated with skeletal abnormalities. In sloths the homeotic vertebral shift involves a large part of the vertebral column. As such, similarity is greatest with mice mutant for genes upstream of Hox. Conclusions We found no skeletal abnormalities in specimens of sister taxa with a normal number of cervical vertebrae. However, we always found such abnormalities in conspecifics with an abnormal number, as in many of the investigated dugongs. These findings strongly support the hypothesis that the evolutionary constraints on changes of the number of cervical vertebrae in mammals is due to deleterious pleitropic effects. We hypothesize that in sloths and manatees low metabolic and activity rates severely reduce the usual stabilizing selection, allowing the breaking of the pleiotropic constraints. This probably also applies to dugongs, although to a lesser extent.
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Lu YW, Li J, Guo WJ. Expression and clinicopathological significance of Mel-18 and Bmi-1 mRNA in gastric carcinoma. JOURNAL OF EXPERIMENTAL & CLINICAL CANCER RESEARCH : CR 2010; 29:143. [PMID: 21059209 PMCID: PMC2993658 DOI: 10.1186/1756-9966-29-143] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/31/2010] [Accepted: 11/08/2010] [Indexed: 01/03/2023]
Abstract
Background The Polycomb group (PcG) genes are a class of regulators responsible for maintaining homeotic gene expression throughout cell division. PcG expression is deregulated in some types of human cancer. Both Bmi-1 and Mel-18 are of the key PcG proteins. We investigate the expression and clinicopathological roles of Mel-18 and Bmi-1 mRNA in gastric cancer. Methods The expression of Mel-18 and Bmi-1 in a series of 71 gastric cancer tissues and paired normal mucosal tissues distant from the tumorous lesion was assayed by quantitative real time RT-PCR. The correlation between Mel-18 and Bmi-1 mRNA expression, and between Mel-18 or Bmi-1 mRNA level and clinicopathological characteristics were analyzed. Results Expression of Mel-18 and Bmi-1 genes was variably detected, but overexpression of Bmi-1 mRNA and decreased expression of Mel-18 mRNA were the most frequent alteration. In addition, the expression of Bmi-1 and Mel-18 mRNA inversely correlates in gastric tumors. Moreover, a significant positive correlation between Bmi-1 overexpression and tumor size, depth of invasion, or lymph node metastasis, and a significant negative correlation between Mel-18 low-expression with lymph node metastasis or the clinical stage were observed. Conclusion Our data suggest that Mel-18 and Bmi-1 may play crucial but opposite roles in gastric cancer. Decreased Mel-18 and increased Bmi-1 mRNA expression was associated with the carcinogenesis and progression of gastric cancer. It is possible to list Bmi-1 and Mel-18 as biomarkers for predicting the prognosis of gastric cancer.
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Affiliation(s)
- You-Wei Lu
- Department of Medical Oncology, Fudan University Shanghai Cancer Center; China.
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27
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Hu D, Wu J, Hu F, Yang Y, Liang C, Chen J, Wang L, Wang P, Wang X, Xu J, Hu X, Yu X. Stage and tissue specific differences in SjBMI1, a Polycomb protein in Schistosoma japonicum. Parasitol Res 2010; 106:677-82. [PMID: 20098996 DOI: 10.1007/s00436-010-1734-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2009] [Accepted: 01/04/2010] [Indexed: 12/16/2022]
Abstract
Polycomb group protein BMI1, plays a central role in the stem cell pluripotency and development in metazoans. A gene encoding BMI1 homologue in the Schistosoma japonicum (SjBMI1) was cloned and identified. The deduced amino acid sequence shows high identity to the homologues from Schistosoma mansoni and Homo sapiens. Quantitative real time polymerase chain reaction (RT-PCR) and Western blot analysis revealed that the SjBMI1 is highly expressed in adult worms and eggs, not in cercariae. By immunofluorescent studies, SjBMI1 was localized to testes, ovaries of mixed sex infected adult worms, but not of single sex infected adult worms. The study reveals the SjBMI1 expression profile in developmental stages and localization characteristic and provides a clue that it may be associated with reproductive development of S. japonicum.
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Affiliation(s)
- Dong Hu
- Department of Parasitology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, People's Republic of China
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Abstract
Glioblastoma multiforme (GBM) is one of the most common and aggressive types of brain tumors. In GBM, a subpopulation of CD133-positive cancer initiating cells displays stem cell characteristics. The Polycomb group (PcG) and oncogene BMI1 is part of the Polycomb repressive complex 1 (PRC1) that regulates gene expression by modifying chromatin organization. Here we show that BMI1 is expressed in human GBM tumors and highly enriched in CD133-positive cells. Stable BMI1 knockdown using short hairpin RNA-expressing lentiviruses resulted in inhibition of clonogenic potential in vitro and of brain tumor formation in vivo. Cell biology studies support the notion that BMI1 prevents CD133-positive cell apoptosis and/or differentiation into neurons and astrocytes, depending on the cellular context. Gene expression analyses suggest that BMI1 represses alternate tumor suppressor pathways that attempt to compensate for INK4A/ARF/P53 deletion and PI(3)K/AKT hyperactivity. Inhibition of EZH2, the main component of the PRC2, also impaired GBM tumor growth. Our results reveal that PcG proteins are involved in GBM tumor growth and required to sustain cancer initiating stem cell renewal.
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Yakushiji N, Yokoyama H, Tamura K. Repatterning in amphibian limb regeneration: A model for study of genetic and epigenetic control of organ regeneration. Semin Cell Dev Biol 2009; 20:565-74. [DOI: 10.1016/j.semcdb.2008.12.007] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2008] [Revised: 12/09/2008] [Accepted: 12/13/2008] [Indexed: 02/05/2023]
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30
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Becker M, Korn C, Sienerth AR, Voswinckel R, Luetkenhaus K, Ceteci F, Rapp UR. Polycomb group protein Bmi1 is required for growth of RAF driven non-small-cell lung cancer. PLoS One 2009; 4:e4230. [PMID: 19156217 PMCID: PMC2626631 DOI: 10.1371/journal.pone.0004230] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2008] [Accepted: 12/05/2008] [Indexed: 01/02/2023] Open
Abstract
BACKGROUND We have previously described a RAF oncogene driven transgenic mouse model for non small cell lung cancer (NSCLC). Here we examine whether tumor initiation and growth requires the stem cell self-renewal factor Bmi1. PRINCIPAL FINDINGS In order to evaluate Bmi1 function in NSCLC two founder lines that differ in incidence and latency of tumor formation were compared. Ablation of Bmi1 expression in both lines had a dramatically decreased tumor growth. As the line with shorter latency matched the life span of Bmi1 knock out mice, these mice were chosen for further study. The absence of Bmi1 did not decrease the number of tumor initiation in these mice as only the size and not the number of tumors decreased. Reduction in tumor growth resulted from an increase in cell death and decrease in cell cycle progression that corresponded with up-regulation of the p16(INK4a) and p19(ARF). SIGNIFICANCE The data identifies Bmi1 as an important factor for expansion but not initiation of RAF driven NSCLC.
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Affiliation(s)
- Matthias Becker
- Bayerisches Krebsforschungszentrum (MSZ), University of Wuerzburg, Wuerzburg, Germany
| | - Christian Korn
- Bayerisches Krebsforschungszentrum (MSZ), University of Wuerzburg, Wuerzburg, Germany
| | - Arnold R. Sienerth
- Bayerisches Krebsforschungszentrum (MSZ), University of Wuerzburg, Wuerzburg, Germany
| | - Robert Voswinckel
- University of Giessen Lung Center, Department of Internal Medicine, University Hospital Giessen, Giessen, Germany
| | - Katharina Luetkenhaus
- Bayerisches Krebsforschungszentrum (MSZ), University of Wuerzburg, Wuerzburg, Germany
| | - Fatih Ceteci
- Bayerisches Krebsforschungszentrum (MSZ), University of Wuerzburg, Wuerzburg, Germany
| | - Ulf R. Rapp
- Bayerisches Krebsforschungszentrum (MSZ), University of Wuerzburg, Wuerzburg, Germany
- * E-mail:
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Fulcher ML, Gabriel SE, Olsen JC, Tatreau JR, Gentzsch M, Livanos E, Saavedra MT, Salmon P, Randell SH. Novel human bronchial epithelial cell lines for cystic fibrosis research. Am J Physiol Lung Cell Mol Physiol 2008; 296:L82-91. [PMID: 18978040 DOI: 10.1152/ajplung.90314.2008] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Immortalization of human bronchial epithelial (hBE) cells often entails loss of differentiation. Bmi-1 is a protooncogene that maintains stem cells, and its expression creates cell lines that recapitulate normal cell structure and function. We introduced Bmi-1 and the catalytic subunit of telomerase (hTERT) into three non-cystic fibrosis (CF) and three DeltaF508 homozygous CF primary bronchial cell preparations. This treatment extended cell life span, although not as profoundly as viral oncogenes, and at passages 14 and 15, the new cell lines had a diploid karyotype. Ussing chamber analysis revealed variable transepithelial resistances, ranging from 200 to 1,200 Omega.cm(2). In the non-CF cell lines, short-circuit currents were stimulated by forskolin and inhibited by CFTR(inh)-172 at levels mostly comparable to early passage primary cells. CF cell lines exhibited no forskolin-stimulated current and minimal CFTR(inh)-172 response. Amiloride-inhibitable and UTP-stimulated currents were present, but at lower and higher amplitudes than in primary cells, respectively. The cells exhibited a pseudostratified morphology, with prominent apical membrane polarization, few apoptotic bodies, numerous mucous secretory cells, and occasional ciliated cells. CF and non-CF cell lines produced similar levels of IL-8 at baseline and equally increased IL-8 secretion in response to IL-1beta, TNF-alpha, and the Toll-like receptor 2 agonist Pam3Cys. Although they have lower growth potential and more fastidious growth requirements than viral oncogene transformed cells, Bmi-1/hTERT airway epithelial cell lines will be useful for several avenues of investigation and will help fill gaps currently hindering CF research and therapeutic development.
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Affiliation(s)
- M L Fulcher
- Univ. of North Carolina Cystic Fibrosis Center, CB 7248, Rm. 4011 Thurston-Bowles Bldg., Chapel Hill, NC 27599, USA
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Abstract
The papillomavirus life cycle is intimately coupled to the differentiation state of the infected epithelium. Since papillomaviruses lack most of the rate-limiting enzymes required for genome synthesis, they need to uncouple keratinocyte differentiation from cell cycle arrest and maintain or reestablish a replication-competent state within terminally differentiated keratinocytes. The human papillomavirus (HPV) E7 protein appears to be a major determinant for this activity and induces aberrant S-phase entry through the inactivation of the retinoblastoma tumor suppressor and related pocket proteins. In addition, E7 can abrogate p21 and p27. Together, this leads to the activation of E2F1 to E2F5, enhanced expression of E2F-responsive genes, and increased cdk2 activity. E2F6 is a pRB-independent, noncanonical member of the E2F transcription factor family that acts as a transcriptional repressor. E2F6 expression is activated in S phase through an E2F-dependent mechanism and thus may provide a negative-feedback mechanism that slows down S-phase progression and/or exit in response to the activation of the other E2F transcription factors. Here, we show that low- and high-risk HPV E7 proteins, as well as simian virus 40 T antigen and adenovirus E1A, can associate with and inactivate the transcriptional repression activity of E2F6, thereby subverting a critical cellular defense mechanism. This may result in the extended S-phase competence of HPV-infected cells. E2F6 is a component of polycomb group complexes, which bind to silenced chromatin and are critical for the maintenance of cell fate. We show that E7-expressing cells show decreased staining for E2F6/polycomb complexes and that this is at least in part dependent on the association with E2F6.
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Silva J, García JM, Peña C, García V, Domínguez G, Suárez D, Camacho FI, Espinosa R, Provencio M, España P, Bonilla F. Implication of polycomb members Bmi-1, Mel-18, and Hpc-2 in the regulation of p16INK4a, p14ARF, h-TERT, and c-Myc expression in primary breast carcinomas. Clin Cancer Res 2007; 12:6929-36. [PMID: 17145810 DOI: 10.1158/1078-0432.ccr-06-0788] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE Deregulation of mammalian Polycomb group (PcG) members may contribute to human carcinogenesis. p16INK4a and p14ARF tumor suppressors, human telomerase reverse transcriptase (h-TERT), and oncoprotein c-Myc have been implicated in the regulation of the cell cycle and proliferation mediated by PcG proteins, mainly Bmi-1, in mice and in cell culture experiments. Here, we examine whether these in vitro findings can be extrapolated to the in vivo situation. EXPERIMENTAL DESIGN We measure the expression of PcG members Bmi-1, Mel-18, and Hpc-2 and their potential targets by reverse transcription-PCR, immunostaining, and Western blotting in a series of 134 breast carcinomas and correlate the data with several clinical-pathologic variables of the tumors. RESULTS Expression of PcG genes was variably detected, but overexpression of Bmi-1 was the most frequent PcG alteration observed. In addition, statistical direct correlation in expression level of the three PcG members was detected. A correlation between c-Myc and Bmi-1 expression levels was observed; however, there was no correlation between expression of Bmi-1 and p16INK4a, p14ARF, or h-TERT. However, expression of the other PcG members Mel-18 and Hpc-2 correlated with the cell cycle regulators. Moreover, PcG mRNA-altered expression correlated significantly with certain clinical-pathologic variables associated with poor prognosis. CONCLUSIONS Our data suggest that the oncogenic role of Bmi-1 in human primary breast carcinomas is not determined by its capacity to inhibit INK4a/ARF proteins or to induce telomerase activity.
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Affiliation(s)
- Javier Silva
- Department of Medical Oncology, Hospital Universitario Puerta de Hierro, Madrid, Spain
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Scott CL, Gil J, Hernando E, Teruya-Feldstein J, Narita M, Martínez D, Visakorpi T, Mu D, Cordon-Cardo C, Peters G, Beach D, Lowe SW. Role of the chromobox protein CBX7 in lymphomagenesis. Proc Natl Acad Sci U S A 2007; 104:5389-94. [PMID: 17374722 PMCID: PMC1828941 DOI: 10.1073/pnas.0608721104] [Citation(s) in RCA: 129] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Chromobox 7 (CBX7) is a chromobox family protein and a component of the Polycomb repressive complex 1 (PRC1) that extends the lifespan of cultured epithelial cells and can act independently of BMI-1 to repress the INK4a/ARF tumor suppressor locus. To determine whether CBX7 might be oncogenic, we examined its expression pattern in a range of normal human tissues and tumor samples. CBX7 was expressed at high levels in germinal center lymphocytes and germinal center-derived follicular lymphomas, where elevated expression correlated with high c-Myc expression and a more advanced tumor grade. By targeting Cbx7 expression to the lymphoid compartment in mice, we showed that Cbx7 can initiate T cell lymphomagenesis and cooperate with c-Myc to produce highly aggressive B cell lymphomas. Furthermore, Cbx7 repressed transcription from the Ink4a/Arf locus and acted epistatically to the Arf-p53 pathway during tumorigenesis. These data identify CBX7 as a chromobox protein causally linked to cancer development and may help explain the low frequency of INK4a/ARF mutations observed in human follicular lymphoma.
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Pardal R, Molofsky AV, He S, Morrison SJ. Stem cell self-renewal and cancer cell proliferation are regulated by common networks that balance the activation of proto-oncogenes and tumor suppressors. COLD SPRING HARBOR SYMPOSIA ON QUANTITATIVE BIOLOGY 2006; 70:177-85. [PMID: 16869752 DOI: 10.1101/sqb.2005.70.057] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Networks of proto-oncogenes and tumor suppressors that control cancer cell proliferation also regulate stem cell self-renewal and possibly stem cell aging. Proto-oncogenes promote regenerative capacity by promoting stem cell function but must be balanced with tumor suppressor activity to avoid neoplastic proliferation. Conversely, tumor suppressors inhibit regenerative capacity by promoting cell death or senescence in stem cells. For example, the polycomb family proto-oncogene, Bmi-1, is consistently required for the self-renewal of diverse adult stem cells, as well as for the proliferation of cancer cells in the same tissues. Bmi-1 promotes stem cell self-renewal partly by repressing the expression of Ink4a and Arf, tumor suppressor genes that are commonly deleted in cancer. Despite ongoing Bmi-1 expression, Ink4a expression increases with age, potentially reducing stem cell frequency and function. Increased tumor suppressor activity during aging therefore may partly account for age-related declines in stem cell function. Thus, networks of proto-oncogenes and tumor suppressors have evolved to coordinately regulate stem cell function throughout life. Imbalances within such networks cause cancer or premature declines in stem cell activity that resemble accelerated aging.
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Affiliation(s)
- R Pardal
- Howard Hughes Medical Institute and Department of Internal Medicine, University of Michigan, Ann Arbor, 48109-0934, USA
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Okada A, Fujiwara M. Molecular approaches to developmental malformations using analogous forms of valproic acid. Congenit Anom (Kyoto) 2006; 46:68-75. [PMID: 16732764 DOI: 10.1111/j.1741-4520.2006.00105.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The teratogenic potential of valproic acid has been well established both in experimental models and in human clinical studies. Evidence from many previous studies has shown that VPA is an appropriate drug model for studying chemical structure-teratogenicity relationships. Using molecular techniques of DNA microarray (GeneChip system) or quantitative real-time polymerase chain reaction with low teratogenic VPA analogs as comparative control drugs, we attempted to identify the genes involved with the molecular mechanisms of VPA teratogenicity in the neural tube and the axial skeleton of the mouse embryo. The recent development of DNA microarray enables a genome-wide approach to the identification of genes correlated with the teratogenicity of chemicals (teratogenomics). The VPA-induced changes in gene expression seen during mouse embryogenesis provides information for understanding how VPA disrupts normal embryonic development, and also provides leads for the development of safer medicines.
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Affiliation(s)
- Akinobu Okada
- Drug Safety Research Laboratories, Astellas Pharma, Yodogawa-ku, Osaka, Japan.
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Kazanjian A, Gross EA, Grimes HL. The growth factor independence-1 transcription factor: new functions and new insights. Crit Rev Oncol Hematol 2006; 59:85-97. [PMID: 16716599 PMCID: PMC2830489 DOI: 10.1016/j.critrevonc.2006.02.002] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2005] [Revised: 01/30/2006] [Accepted: 02/01/2006] [Indexed: 12/21/2022] Open
Abstract
The growth factor independence-1 (Gfi1) transcription factor is required for proper development of neuroendocrine cells, sensory neurons, and blood. Patients with mutations in Gfi1 exhibit severe congenital neutropenia (SCN) or non-immune chronic idiopathic neutropenia of adults. Gfi1 was initially described as an oncoprotein that mediates tumor progression in a mouse model of leukemia; however, recent data suggest that Gfi1 may act as either an oncogene or an anti-proliferative tumor suppressor gene depending on the cell type. Here we review the latest literature on Gfi1, and emphasize its role in the hematopoietic, sensory and neuroendocrine systems.
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Affiliation(s)
- Avedis Kazanjian
- Institute for Cellular Therapeutics, University of Louisville School of Medicine, Louisville, KY 40202, USA
- Department of Biochemistry and Molecular Biology, University of Louisville School of Medicine, Louisville, KY 40202, USA
| | - Eleanore A. Gross
- Institute for Cellular Therapeutics, University of Louisville School of Medicine, Louisville, KY 40202, USA
| | - H. Leighton Grimes
- Institute for Cellular Therapeutics, University of Louisville School of Medicine, Louisville, KY 40202, USA
- Department of Surgery, University of Louisville School of Medicine, Louisville, KY 40202, USA
- Department of Biochemistry and Molecular Biology, University of Louisville School of Medicine, Louisville, KY 40202, USA
- Corresponding author. Present address: Cincinnati Children’s Hospital Medical Center, Division of Immunobiology – MLC 7038, 3333 Burnet Avenue, Room 5564, Cincinnati, OH 45229-3039, USA. Tel.: +1 513 636 6089; fax: +1 513 636 5355.
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38
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Raaphorst FM. Deregulated expression of Polycomb-group oncogenes in human malignant lymphomas and epithelial tumors. Hum Mol Genet 2005; 14 Spec No 1:R93-R100. [PMID: 15809278 DOI: 10.1093/hmg/ddi111] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Genes belonging to the Polycomb-group (PcG) are epigenetic gene silencers with a vital role in the maintenance of cell identity. They contribute to regulation of various processes in both embryos and adults, including the cell cycle and lymphopoiesis. A growing body of work has linked human PcG genes to various hematological and epithelial cancers, identifying novel mechanisms of malignant transformation and paving the way to development of new cancer treatments and identification of novel diagnostic markers. This review addresses the current insights in the role of PcG genes in development of human malignancies.
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Affiliation(s)
- Frank M Raaphorst
- Department of Pathology, VU Medical Center, De Boelelaan 1117, 1081 HV Amsterdam, The Netherlands.
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Shakhova O, Leung C, Marino S. Bmi1 in development and tumorigenesis of the central nervous system. J Mol Med (Berl) 2005; 83:596-600. [PMID: 15976916 DOI: 10.1007/s00109-005-0682-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2005] [Accepted: 04/05/2005] [Indexed: 12/16/2022]
Abstract
The role of the Polycomb group gene Bmi1 in proliferation control of lymphoid and neuronal progenitors as well as in self-renewal of haematopoietic and neural stem cells has been recently demonstrated. Here we review these recent findings with particular regard to their implications for central nervous system development and tumorigenesis.
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Affiliation(s)
- Olga Shakhova
- Institute of Clinical Pathology, University Hospital, Schmelzbergstrasse 12, 8091 Zürich, Switzerland
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40
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Okada A, Aoki Y, Kushima K, Kurihara H, Bialer M, Fujiwara M. Polycomb homologs are involved in teratogenicity of valproic acid in mice. ACTA ACUST UNITED AC 2005; 70:870-9. [PMID: 15523661 DOI: 10.1002/bdra.20085] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
BACKGROUND Valproic acid (VPA) is widely used to treat epilepsy and bipolar disorder and is also a potent teratogen, but its teratogenic mechanisms are unknown. We have attempted to describe a fundamental role of the Polycomb group (Pc-G) in VPA-induced transformations of the axial skeleton. METHODS Pregnant NMRI mice were given a single subcutaneous injection of vehicle or VPA (800 mg/kg) on gestation day (GD) 8. The expression of genes encoding Polycomb and trithorax groups was measured by quantitative real-time RT-PCR using total RNA isolated from the embryos exposed to vehicle or VPA for 1, 3, and 6 hr. In addition, the use of two less teratogenic antiepileptic chemicals valpromide (VPD) and valnoctamide (VCD) provide reliable evidence to support the relationship between VPA teratogenicity and the Polycomb group. RESULTS At a teratogenic level, VPA inhibits the expression of the Polycomb group genes, including Eed, Ezh2, Zfp144, Bmi1, Cbx2, Rnf2, and YY1 in the mouse embryos. In contrast, neither VPD nor VCD have significant effects on the expression of those genes affected by VPA. The trithorax group (trx-G) gene MLL, which is known to be required to maintain homeobox gene expression such as the Polycomb gene, is not affected by a teratogenic dose of VPA. CONCLUSIONS We propose that, during embryonic development, VPA may affect the gene silencing pathway mediated by the Polycomb group complex. The epigenetic mechanism of VPA teratogenicity on anteroposterior patterning is suspected.
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Affiliation(s)
- Akinobu Okada
- Safety Research Laboratories, Yamanouchi Pharmaceutical Co., Ltd., Tokyo, Japan
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Merks JHM, Smets AM, Van Rijn RR, Kobes J, Caron HN, Maas M, Hennekam RCM. Prevalence of rib anomalies in normal Caucasian children and childhood cancer patients. Eur J Med Genet 2005; 48:113-29. [PMID: 16053903 DOI: 10.1016/j.ejmg.2005.01.029] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2004] [Indexed: 10/25/2022]
Abstract
PURPOSE To evaluate the prevalence of abnormalities of rib development in normal Caucasian children and patients with childhood cancer. MATERIALS AND METHODS Chest radiographs of 881 Caucasian pediatric controls and 906 childhood cancer patients were reviewed, and independently scored by four blinded observers, using strict definitions. Prevalences of 6 major rib anomaly categories in controls were compared to their prevalence in the total group of childhood cancer patients, and the 12 individual larger tumor groups using Chi-square tests. RESULTS Values in the control population were generated for the occurrence of six major rib anomaly categories; cervical rib anomalies were present in 6.1% of controls, aplasia of 12th ribs in 6.6%, lumbar ribs in 0.9%, bifurcations in 0.7%, synostosis-bridging in 0.3%, and segmentations were not found. The overall prevalence of total rib anomalies in cases and controls was equal (14.9% and 14.2%, respectively). Cervical rib anomalies were found significantly more often in cases (8.6%) compared to controls (p-value=0.047), three groups accounting for this higher prevalence: 12.1% of acute lymphoblastic leukemia patients (p=0.011), 18.2% of astrocytoma patients (p=0.023), and 14.7% of germ cell tumor patients (p=0.046) had a cervical rib anomaly. CONCLUSION Prevalence figures for the presence and type of rib anomalies in a large group of normal Caucasian children were generated. In childhood cancer patients a significantly higher prevalence of cervical rib anomalies was demonstrated in patients with acute lymphoblastic leukemia, astrocytoma, and germ cell tumors.
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Affiliation(s)
- Johannes H M Merks
- Department of Pediatric Oncology, Emma Children's Hospital, Academic Medical Center, Amsterdam, The Netherlands.
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Abstract
To be seriously considered, a theory about the pathogenesis of a multiple congenital anomaly syndrome should meet three criteria: (1) it should explain all of the anomalies associated with the syndrome; (2) it should explain why certain anomalies are not associated with the syndrome; and (3) it should predict anomalies that could be associated with the syndrome, but have not yet been described. The theory must eventually pass the ultimate test, that is, molecular confirmation of the proposed mechanism. Several theories about the pathogenesis of CHARGE syndrome have been proposed, but none of these meet the three criteria stated above. In this study, the author proposes that CHARGE syndrome is due to a disruption of mesenchymal-epithelial interaction (epithelial includes ectoderm and endoderm). The theory is tested against the major, minor, and occasional anomalies that are used to make the clinical diagnosis of CHARGE syndrome. Review of the known embryology of the organs and tissues involved in CHARGE syndrome confirms that mesenchymal-epithelial interactions are necessary for proper formation of these organs and tissues. The presence of limb anomalies in approximately one-third of CHARGE syndrome patients fulfills criteria #3 above, in that limb anomalies were not felt to be a part of CHARGE syndrome until relatively recently. It is known that some patients with chromosomal abnormalities have a phenotype that overlaps with CHARGE syndrome. Given that critical developmental pathways must be robust and redundant in order to minimize errors, it may be that disruption of more than one gene is necessary to generate the CHARGE phenotype, as has been proposed for the holoprosencephaly sequence. Mutations and deletions of CHD7 have recently been identified as causing CHARGE syndrome in more than 50% of tested patients. Given this gene classes' putative role as a general controller of developmental gene expression as well as mesodermal patterning, it would fit the hypothesized mechanisms discussed in the study.
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Affiliation(s)
- Marc S Williams
- Department of Pediatrics, Gundersen Lutheran Medical Center, La Crosse, Wisconsin, USA.
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Oostra RJ, Hennekam RCM, de Rooij L, Moorman AFM. Malformations of the axial skeleton inMuseum Vrolik I: Homeotic transformations and numerical anomalies. Am J Med Genet A 2005; 134:268-81. [PMID: 15732082 DOI: 10.1002/ajmg.a.30639] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The Museum Vrolik collection of anatomical specimens in Amsterdam, The Netherlands, comprises over 5,000 specimens of human and animal anatomy, embryology, pathology, and congenital anomalies. Recently, we rediagnosed a subset of the collection comprising dried human trunk skeletons and cranial base preparations presenting with homeotic transformations (vertebral phenotypic shifts) and numerical vertebral anomalies. We identified 11 trunk skeletons with either anterior or posterior homeotic transformations (AHT or PHT), 5 trunk skeletons with either less or more than the normal number of vertebrae, and well over a hundred cranial base preparations with either AHT (atlas-assimilation) or PHT (occipital vertebra). We found that, although homeotic transformations and numerical anomalies are distinct conditions, both can be described in terms of mismatch between homeotic patterning and morphological segmentation of the paraxial mesoderm. Therefore these two processes are perhaps not as tightly linked as they may seem on the basis of recent molecular studies. In homeotic transformations there is a constant mismatch between homeotic patterning and morphological segmentation throughout the affected region of the vertebral column. In numerical anomalies there is a variable mismatch between homeotic patterning and morphological segmentation, either because of stretching or squeezing of the homeotic pattern or because of oligo- or polysegmentation of the presomitic mesoderm (PSM). Homeotic transformations of the axial skeleton have an incidence of about 1%-5%, apart from their occurrence in malformation syndromes. Of the various etiological possibilities, explaining their frequent but mostly sporadic occurrence, maternal hyperthermia seems an attractive candidate.
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Affiliation(s)
- Roelof-Jan Oostra
- Department of Anatomy and Embryology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
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Antonarakis SE, Lyle R, Dermitzakis ET, Reymond A, Deutsch S. Chromosome 21 and down syndrome: from genomics to pathophysiology. Nat Rev Genet 2004; 5:725-38. [PMID: 15510164 DOI: 10.1038/nrg1448] [Citation(s) in RCA: 436] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The sequence of chromosome 21 was a turning point for the understanding of Down syndrome. Comparative genomics is beginning to identify the functional components of the chromosome and that in turn will set the stage for the functional characterization of the sequences. Animal models combined with genome-wide analytical methods have proved indispensable for unravelling the mysteries of gene dosage imbalance.
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Affiliation(s)
- Stylianos E Antonarakis
- Department of Genetic Medicine and Development, University of Geneva Medical School and University Hospitals of Geneva, 1 rue Michel-Servet, 1211 Geneva, Switzerland.
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Attwooll C, Oddi S, Cartwright P, Prosperini E, Agger K, Steensgaard P, Wagener C, Sardet C, Moroni MC, Helin K. A novel repressive E2F6 complex containing the polycomb group protein, EPC1, that interacts with EZH2 in a proliferation-specific manner. J Biol Chem 2004; 280:1199-208. [PMID: 15536069 DOI: 10.1074/jbc.m412509200] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The transcriptional repressor E2F6 has been identified as a component of two distinct polycomb group protein (PcG)-containing complexes, suggesting a mechanism for the recruitment of repressive complexes to target sequences in DNA. Whereas one complex is involved in the repression of classic E2F target genes in G0, a role for E2F6 within the cell cycle has yet to be defined. We searched for novel E2F6-binding proteins using a yeast two-hybrid screen and identified the PcG protein, EPC1. We showed that, both in vitro and in vivo, E2F6, DP1, and EPC1 form a stable core complex with repressive activity. Furthermore, we identified the proliferation-specific PcG, EZH2, as an EPC1-interacting protein. Using affinity purification, we showed that E2F6, DP1, EPC1, EZH2, and Sin3B co-elute, suggesting the identification of a novel E2F6 complex that exists in vivo in both normal and transformed human cell lines. EZH2 is required for cellular proliferation and consistent with this, EZH2 elutes with the E2F6-EPC1 complex only in proliferating cells. Thus we have identified a novel E2F6-PcG complex (E2F6-EPC1) that interacts with EZH2 and may regulate genes required for cell cycle progression.
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Affiliation(s)
- Claire Attwooll
- European Institute of Oncology, Department of Experimental Oncology, Via Ripamonti 435, Milan, 20141, Italy
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Fraser PE, Sauka-Spengler T. Expression of the polycomb group gene bmi-1 in the early chick embryo. Gene Expr Patterns 2004; 5:23-7. [PMID: 15533814 DOI: 10.1016/j.modgep.2004.06.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2004] [Revised: 06/25/2004] [Accepted: 06/28/2004] [Indexed: 11/27/2022]
Abstract
Bmi-1 is a protooncogene of the polycomb group that has important functions in self-renewal of adult stem cells and maintenance of anterior identity along the embryonic body axis. Despite these important functions, surprisingly little is known about its distribution pattern in the embryo. Here, we have isolated the chick homologue of bmi-1 and examined its expression pattern from gastrulation through neurulation and establishment of organ rudiments. During gastrulation, bmi-1 transcripts were expressed in the epiblast cells adjacent to the primitive streak. During early nervous system development, robust expression was observed in the open neural plate and later in the dorsal neural tube and much of the brain. Bmi-1 expression was also present in the developing heart primordia and the sensory placodes. The data show that bmi-1 is present in, but not restricted to, tissue containing multipotent precursor cells.
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Affiliation(s)
- Paige E Fraser
- Division of Biology, 139-74, California Institute of Technology, Pasadena, CA 91125, USA
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Kim JY, Sawada A, Tokimasa S, Endo H, Ozono K, Hara J, Takihara Y. Defective long-term repopulating ability in hematopoietic stem cells lacking the Polycomb-group gene rae28. Eur J Haematol 2004; 73:75-84. [PMID: 15245505 DOI: 10.1111/j.1600-0609.2004.00268.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The rae28 gene (rae28) is a member of a Polycomb-group (PcG) complex 1, which is known to help maintain transcription states once these have been initiated, by generating heritable higher-order chromatin structures. In this study, we examined the capacity of rae28-deficient (rae28-/-) hematopoietic stem cells (HSCs) to generate long-term marrow reconstitution. rae28-/- fetal liver cells containing 20 competitive repopulation units (CRUs) were able to support the survival of lethally irradiated congenic mice for as long as 6 months. The marrow reconstituted with the rae28-/- cells, however, could not increase HSCs efficiently. This was evidenced by its inability to reconstitute marrow in serial transplantation experiments, as well as by the reduction in HSC-enriched Lin- c-kit+ Sca-1high+ subpopulation in the bone marrow cells. Moreover, the reconstituted marrow produced less than half of the peripheral blood cells in each of the lineages examined. We also monitored the mean stem cell activity (MAS). MAS of rae28-/- CRUs was progressively reduced after transplantation, and after 12 months it was reduced to one-tenth of that of the wild-type. These in vivo results clearly indicate that rae28 is indispensable for the long-term repopulating ability of HSCs. We further referred to the plausible mechanisms underlying defective long-term repopulating ability of rae28-deficient HSCs and argued for its involvement in maintenance of cell proliferation capability as well as that in self-renewal ability.
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Affiliation(s)
- Ji Yoo Kim
- Department of Developmental Biology and Medicine, Osaka Medical Center for Cancer and Cardiovascular Diseases, Osaka, Japan
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Scheijen B, Bronk M, van der Meer T, De Jong D, Bernards R. High incidence of thymic epithelial tumors in E2F2 transgenic mice. J Biol Chem 2003; 279:10476-83. [PMID: 14684733 DOI: 10.1074/jbc.m313682200] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
In virtually all human tumors, genetic and epigenetic alterations have been found which affect the INK4/-CYCLIN D/RB pathway, which regulates cell cycle entry and exit in normal cells. E2F transcription factors are important downstream components of this pathway, which act by controlling the expression of genes involved in DNA replication and cell cycle progression. To determine whether E2F2 deregulation promotes proliferation and tumorigenesis in vivo, we generated E2F2 transgenic mice, in which the Emu and murine pim1 promoter (pp) direct high expression of E2F2 in thymic epithelial cells. Emu-pp-E2F2 mice start to develop cytokeratin- and ER-TR4-positive cortical thymomas from the age of 20 weeks, and within 1 year, nearly all mice succumb to gross thymic epithelial tumors. General thymic morphology is largely maintained, but T cell development is perturbed in thymomas, with proportionately less CD4(+)CD8(+) double-positive thymocytes. In the first 3 months, E2F2 transgenic thymi exhibit only mild epithelial hyperplasia, and thereafter thymomas arise stochastically, probably following additional mutations. Interestingly, Emu-pp-E2F1 mice do not display cortical thymomas. These data argue that E2F2 promotes unscheduled cell division and oncogenic transformation of thymic epithelial cells.
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Affiliation(s)
- Blanca Scheijen
- Division of Molecular Carcinogenesis and Center for Biomedical Genetics, Netherlands Cancer Institute, Amsterdam 1066 CX, Netherlands
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Molofsky AV, Pardal R, Iwashita T, Park IK, Clarke MF, Morrison SJ. Bmi-1 dependence distinguishes neural stem cell self-renewal from progenitor proliferation. Nature 2003; 425:962-7. [PMID: 14574365 PMCID: PMC2614897 DOI: 10.1038/nature02060] [Citation(s) in RCA: 1006] [Impact Index Per Article: 47.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2003] [Accepted: 09/01/2003] [Indexed: 11/09/2022]
Abstract
Stem cells persist throughout life by self-renewing in numerous tissues including the central and peripheral nervous systems. This raises the issue of whether there is a conserved mechanism to effect self-renewing divisions. Deficiency in the polycomb family transcriptional repressor Bmi-1 leads to progressive postnatal growth retardation and neurological defects. Here we show that Bmi-1 is required for the self-renewal of stem cells in the peripheral and central nervous systems but not for their survival or differentiation. The reduced self-renewal of Bmi-1-deficient neural stem cells leads to their postnatal depletion. In the absence of Bmi-1, the cyclin-dependent kinase inhibitor gene p16Ink4a is upregulated in neural stem cells, reducing the rate of proliferation. p16Ink4a deficiency partially reverses the self-renewal defect in Bmi-1-/- neural stem cells. This conserved requirement for Bmi-1 to promote self-renewal and to repress p16Ink4a expression suggests that a common mechanism regulates the self-renewal and postnatal persistence of diverse types of stem cell. Restricted neural progenitors from the gut and forebrain proliferate normally in the absence of Bmi-1. Thus, Bmi-1 dependence distinguishes stem cell self-renewal from restricted progenitor proliferation in these tissues.
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Affiliation(s)
- Anna V Molofsky
- Howard Hughes Medical Institute, and Departments of Internal Medicine and Cell and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109-0934, USA
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Lessard J, Sauvageau G. Polycomb group genes as epigenetic regulators of normal and leukemic hemopoiesis. Exp Hematol 2003; 31:567-85. [PMID: 12842702 DOI: 10.1016/s0301-472x(03)00081-x] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Epigenetic modification of chromatin structure underlies the differentiation of pluripotent hemopoietic stem cells (HSCs) into their committed/differentiated progeny. Compelling evidence indicates that Polycomb group (PcG) genes play a key role in normal and leukemic hemopoiesis through epigenetic regulation of HSC self-renewal/proliferation and commitment. The PcG proteins are constituents of evolutionary highly conserved molecular pathways regulating cell fate in several other tissues through diverse mechanisms, including 1) regulation of self-renewal/proliferation, 2) regulation of senescence/immortalization, 3) interaction with the initiation transcription machinery, 4) interaction with chromatin-condensation proteins, 5) modification of histones, 6) inactivation of paternal X chromosome, and 7) regulation of cell death. It is therefore not surprising that PcG genes lead to pleiotropic phenotypes when mutated and have been associated with malignancies in several systems in both mice and humans. Although much remains to be learned regarding the PcG mechanism(s) of action, advances in identifying the functional domains and enzymatic activities of these multimeric protein complexes have provided insights into how PcG proteins accomplish such processes. Some of the new insights into a role for the PcG cellular memory system in regulating normal and leukemic hemopoiesis are reviewed here, with special emphasis on their potential involvement in epigenetic regulation of gene expression through modification of chromatin structure.
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Affiliation(s)
- Julie Lessard
- Laboratory of Molecular Genetics of Hemopoietic Stem Cells, Clinical Research Institute of Montreal, Montreal, Quebec, Canada
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