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Chen Y, Lian G, Zhang Q, Zeng L, Qian C, Chen S, Huang K. Overexpression of Bmi-1 induces the malignant transformation of gastric epithelial cells in vitro. Oncol Res 2014; 21:33-41. [PMID: 24330850 DOI: 10.3727/096504013x13786659070316] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Oncogene Bmi-1 (B-cell-specific Moloney murine leukemia virus integration site 1) has attracted much attention for its involvement in the initiation of a variety of tumors. Our previous study showed that Bmi-1 was highly expressed in gastric cancer and correlated with patient prognosis. However, whether aberrant Bmi-1 expression was critical for the transformation of gastric epithelial cells remains unknown. In this study, we stably expressed Bmi-1 in a human gastric epithelial immortalized cell line, GES-1. The overexpression of Bmi-1 promoted cell growth and proliferation, inhibited apoptosis, enhanced clone formation capability, possessed the characteristics of anchorage-independent growth, and increased migration and invasion abilities. Therefore, our findings demonstrated that ectopic expression of Bmi-1 played an important role in the malignant transformation of gastric epithelial cells.
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Affiliation(s)
- Yinting Chen
- Department of Gastroenterology, Sun Yat-Sen Memorial Hospital of Sun Yat-Sen University, Guangzhou, China
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2
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Steffen PA, Ringrose L. What are memories made of? How Polycomb and Trithorax proteins mediate epigenetic memory. Nat Rev Mol Cell Biol 2014; 15:340-56. [PMID: 24755934 DOI: 10.1038/nrm3789] [Citation(s) in RCA: 249] [Impact Index Per Article: 24.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
In any biological system with memory, the state of the system depends on its history. Epigenetic memory maintains gene expression states through cell generations without a change in DNA sequence and in the absence of initiating signals. It is immensely powerful in biological systems - it adds long-term stability to gene expression states and increases the robustness of gene regulatory networks. The Polycomb group (PcG) and Trithorax group (TrxG) proteins can confer long-term, mitotically heritable memory by sustaining silent and active gene expression states, respectively. Several recent studies have advanced our understanding of the molecular mechanisms of this epigenetic memory during DNA replication and mitosis.
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Affiliation(s)
- Philipp A Steffen
- Institute of Molecular Biotechnology (IMBA), Dr. Bohr-Gasse 3, 1030 Vienna, Austria
| | - Leonie Ringrose
- Institute of Molecular Biotechnology (IMBA), Dr. Bohr-Gasse 3, 1030 Vienna, Austria
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3
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Klose RJ, Cooper S, Farcas AM, Blackledge NP, Brockdorff N. Chromatin sampling--an emerging perspective on targeting polycomb repressor proteins. PLoS Genet 2013; 9:e1003717. [PMID: 23990804 PMCID: PMC3749931 DOI: 10.1371/journal.pgen.1003717] [Citation(s) in RCA: 103] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Affiliation(s)
- Robert J. Klose
- Laboratory of Chromatin Biology and Transcription, Department of Biochemistry, University of Oxford, Oxford, United Kingdom
- * E-mail: (RJK); (NB)
| | - Sarah Cooper
- Laboratory of Developmental Epigenetics, Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | - Anca M. Farcas
- Laboratory of Chromatin Biology and Transcription, Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | - Neil P. Blackledge
- Laboratory of Chromatin Biology and Transcription, Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | - Neil Brockdorff
- Laboratory of Developmental Epigenetics, Department of Biochemistry, University of Oxford, Oxford, United Kingdom
- * E-mail: (RJK); (NB)
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4
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Qüesta JI, Walbot V, Casati P. Mutator transposon activation after UV-B involves chromatin remodeling. Epigenetics 2010; 5:352-63. [PMID: 20421734 DOI: 10.4161/epi.5.4.11751] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Spontaneous silencing of MuDR/Mu transposons occurs in approximately 10-100% of the progeny of an active plant, and once silenced reactivation is very rare. To date, only radiation treatments have reactivated silenced Mu; for example UV-B radiation reactivated Mutator activities. Here we have investigated possible mechanisms by which UV-B could reactivate Mu transposons by monitoring transcript abundance, epigenetic DNA marks, and chromatin factors associated with these elements. We demonstrate that both mudrA and B transcripts are expressed at higher levels after an 8 h-UV-B treatment, in both active Mutator and silencing plants, and that different chromatin remodeling events occur in the promoter regions of MuDR than in non-autonomous Mu1 elements. Increased transcript abundance is accompanied by an increase in histone H3 acetylation and by decreased DNA and H3K9me2 methylation. No changes in siRNA levels were detected. In contrast, the decrease in H3K9me2 present at Mu elements after UV-B is significant in silencing plants, suggesting that early changes in H3 methylation in K9, chromatin remodeling, and transcription factor binding contribute directly to transposon reactivation by UV-B in maize.
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Affiliation(s)
- Julia I Qüesta
- Centro de Estudios Fotosintéticos y Bioquímicos, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
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5
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Wang Q, Li WL, You P, Su J, Zhu MH, Xie DF, Zhu HY, He ZY, Li JX, Ding XY, Wang X, Hu YP. Oncoprotein BMI-1 induces the malignant transformation of HaCaT cells. J Cell Biochem 2009; 106:16-24. [PMID: 19021148 DOI: 10.1002/jcb.21969] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
BMI-1 (B-cell-specific Moloney murine leukemia virus integration site 1), a novel oncogene, has attracted much attention in recent years for its involvement in the initiation of a variety of tumors. Recent evidence showed that BMI-1 was highly expressed in neoplastic skin lesions. However, whether dysregulated BMI-1 expression is causal for the transformation of skin cells remains unknown. In this study, we stably expressed BMI-1 in a human keratinocyte cell line, HaCaT. The expression of wild-type BMI-1 induced the malignant transformation of HaCaT cells in vitro. More importantly, we found that expression of BMI-1 promoted formation of squamous cell carcinomas in vivo. Furthermore, we showed that BMI-1 expression led to the downregulation of tumor suppressors, such as p16INK4a and p14ARF, cell adhesion molecules, such as E-Cadherin, and differentiation related factor, such as KRT6. Therefore, our findings demonstrated that dysregulated BMI-1 could indeed lead to keratinocytes transformation and tumorigenesis, potentially through promoting cell cycle progression and increasing cell mobility.
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Affiliation(s)
- Qian Wang
- Department of Cell Biology, Second Military Medical University, Shanghai 200433, PR China
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6
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Woodhouse MR, Freeling M, Lisch D. Initiation, establishment, and maintenance of heritable MuDR transposon silencing in maize are mediated by distinct factors. PLoS Biol 2007; 4:e339. [PMID: 16968137 PMCID: PMC1563492 DOI: 10.1371/journal.pbio.0040339] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2006] [Accepted: 08/16/2006] [Indexed: 11/19/2022] Open
Abstract
Paramutation and transposon silencing are two epigenetic phenomena that have intrigued and puzzled geneticists for decades. Each involves heritable changes in gene activity without changes in DNA sequence. Here we report the cloning of a gene whose activity is required for the maintenance of both silenced transposons and paramutated color genes in maize. We show that this gene, Mop1 (Mediator of paramutation1) codes for a putative RNA-dependent RNA polymerase, whose activity is required for the production of small RNAs that correspond to the MuDR transposon sequence. We also demonstrate that although Mop1 is required to maintain MuDR methylation and silencing, it is not required for the initiation of heritable silencing. In contrast, we present evidence that a reduction in the transcript level of a maize homolog of the nucleosome assembly protein 1 histone chaperone can reduce the heritability of MuDR silencing. Together, these data suggest that the establishment and maintenance of MuDR silencing have distinct requirements.
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Affiliation(s)
- Margaret Roth Woodhouse
- Department of Plant and Microbial Biology, University of California Berkeley, Berkeley, California, United States of America
| | - Michael Freeling
- Department of Plant and Microbial Biology, University of California Berkeley, Berkeley, California, United States of America
| | - Damon Lisch
- Department of Plant and Microbial Biology, University of California Berkeley, Berkeley, California, United States of America
- * To whom correspondence should be addressed. E-mail:
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7
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Melcon G, Kozlov S, Cutler DA, Sullivan T, Hernandez L, Zhao P, Mitchell S, Nader G, Bakay M, Rottman JN, Hoffman EP, Stewart CL. Loss of emerin at the nuclear envelope disrupts the Rb1/E2F and MyoD pathways during muscle regeneration. Hum Mol Genet 2006; 15:637-51. [PMID: 16403804 DOI: 10.1093/hmg/ddi479] [Citation(s) in RCA: 179] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Emery-Dreifuss muscular dystrophy (EDMD1) is caused by mutations in either the X-linked gene emerin (EMD) or the autosomal lamin A/C (LMNA) gene. Here, we describe the derivation of mice lacking emerin in an attempt to derive a mouse model for EDMD1. Although mice lacking emerin show no overt pathology, muscle regeneration in these mice revealed defects. A bioinformatic array analysis of regenerating Emd null muscle revealed abnormalities in cell-cycle parameters and delayed myogenic differentiation, which were associated with perturbations to transcriptional pathways regulated by the retinoblastoma (Rb1) and MyoD genes. Temporal activation of MyoD transcriptional targets was significantly delayed, whereas targets of the Rb1/E2F transcriptional repressor complex remained inappropriately active. The inappropriate modulation of Rb1/MyoD transcriptional targets was associated with up-regulation of Rb1, MyoD and their co-activators/repressors transcripts, suggesting a compensatory effort to overcome a molecular block to differentiation at the myoblast/myotube transition during regeneration. This compensation appeared to be effective for MyoD transcriptional targets, although was less effective for Rb1 targets. Analysis of Rb1 phosphorylation states showed prolonged hyper-phosphorylation at key developmental stages in Emd null myogenic cells, both in vivo and in vitro. We also analyzed the same pathways in Lmna null muscle, which shows extensive dystrophy. Surprisingly, Lmna null muscle did not show the same perturbations to Rb- and MyoD-dependent pathways. We did observe increased transcriptional expression of Lap2alpha and delayed expression of Rb1, which may regulate alternative transcriptional pathways in the Lmna null myoblasts. We suggest that the dominant LMNA mutations seen in many clinically disparate laminopathies may similarly alter Rb function, with regard to either the timing of exit from the cell cycle or terminal differentiation programs or both.
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Affiliation(s)
- Gisela Melcon
- Research Center for Genetic Medicine, Children's National Medical Center, Washington DC, USA
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8
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Ringrose L, Paro R. Epigenetic regulation of cellular memory by the Polycomb and Trithorax group proteins. Annu Rev Genet 2005; 38:413-43. [PMID: 15568982 DOI: 10.1146/annurev.genet.38.072902.091907] [Citation(s) in RCA: 775] [Impact Index Per Article: 40.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
During the development of multicellular organisms, cells become different from one another by changing their genetic program in response to transient stimuli. Long after the stimulus is gone, "cellular memory" mechanisms enable cells to remember their chosen fate over many cell divisions. The Polycomb and Trithorax groups of proteins, respectively, work to maintain repressed or active transcription states of developmentally important genes through many rounds of cell division. Here we review current ideas on the protein and DNA components of this transcriptional memory system and how they interact dynamically with each other to orchestrate cellular memory for several hundred genes.
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9
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Henikoff S, Furuyama T, Ahmad K. Histone variants, nucleosome assembly and epigenetic inheritance. Trends Genet 2004; 20:320-6. [PMID: 15219397 DOI: 10.1016/j.tig.2004.05.004] [Citation(s) in RCA: 203] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Affiliation(s)
- Steven Henikoff
- Howard Hughes Medical Institute, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue North, Seattle, WA 98109, USA.
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10
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Lavigne M, Francis NJ, King IFG, Kingston RE. Propagation of silencing; recruitment and repression of naive chromatin in trans by polycomb repressed chromatin. Mol Cell 2004; 13:415-25. [PMID: 14967148 DOI: 10.1016/s1097-2765(04)00006-1] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2003] [Revised: 11/24/2003] [Accepted: 12/10/2003] [Indexed: 11/20/2022]
Abstract
The Polycomb group (PcG) proteins maintain stable and heritable repression of homeotic genes. Typically, Polycomb response elements (PRE) that direct PcG repression are located at great distances (10s of kb) from the promoters of PcG-repressed genes, and it is not known how these PREs can communicate with promoters over such distances. Using Class II mouse PRC core complexes (mPCCs) assembled from recombinant subunits, we investigated how PcG complexes might bridge distant chromosomal regions. Like native and recombinant Drosophila Class II complexes, mPCC represses chromatin remodeling and transcription. Interestingly, mPCC bound to one polynucleosome template can recruit a second template from solution and renders it refractory to transcription and chromatin remodeling. A Drosophila PRC core complex (dPCC) also is able to recruit a second template. Posterior sex combs (PSC), a subunit of dPCC, inhibits chromatin remodeling and transcription efficiently but requires assembly with dRING1 to recruit chromatin. Thus, repression and template bridging require different subunits of PcG complexes, suggesting that long-range effects may be mechanistically distinct from repression.
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Affiliation(s)
- Marc Lavigne
- Department of Molecular Biology Massachusetts General Hospital, Massachusetts 02114, USA.
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11
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Abstract
Local differences in chromatin organisation may profoundly affect the activity of eukaryotic genomes. Regulation at the level of DNA packaging requires the targeting of structural proteins and histone-modifying enzymes to specific sites and their stable or dynamic interaction with the nucleosomal fiber. The "chromodomain", a domain shared by many regulators of chromatin structure, has long been suspected to serve as a module mediating chromatin interactions in a variety of different protein contexts. However, recent functional analyses of a number of different chromodomains revealed an unexpected diversity of interaction targets, including histones, DNA and even RNA. The chromodomains of today seem to have evolved from a common ancestral fold to fulfill various functions in different molecular contexts. Combining information gained from recent functional and structural studies of chromodomains with a bioinformatic classification of their structure could lead to the definition of sequence motifs with predictive quality for chromodomain function.
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Affiliation(s)
- Alexander Brehm
- Adolf-Butenandt-Institut, Molekularbiologie, München, Germany
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12
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Abstract
Cell identity is determined by selective gene activation and by the maintenance of other regulated genes in a silent state. Although activation mechanisms have been dissected in considerable depth, great strides towards an understanding of the molecular control of gene silencing have been made only recently. Molecular hallmarks of silent chromatin and proteins involved in its assembly and maintenance have been identified through genetic, cytological and biochemical studies in a variety of organisms. Immunologists are now beginning to use this knowledge to elucidate mechanisms underlying cell fate decisions and key developmental steps. This review surveys the current knowledge of gene silencing, with an emphasis on studies in lymphocytes that are advancing our general understanding of silencing mechanisms during development.
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Affiliation(s)
- Stephen T Smale
- Howard Hughes Medical Institute and Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, California 90095-1662, USA.
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13
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Abstract
Regulation of stem cell division is of particular interest, both for studies of development and for stem cell therapeutics. In this issue of Neuron, Bello et al. show that the number of divisions of Drosophila neural stem cells is limited, in a region-specific manner, by regulated apoptosis in response to a pulse of expression of the Hox gene abdominal-A (abdA).
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Affiliation(s)
- Andrea H Brand
- Wellcome Trust/Cancer Research UK Institute and Department of Genetics, University of Cambridge, Tennis Court Road, Cambridge CB2 1QR, United Kingdom
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14
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Bello BC, Hirth F, Gould AP. A pulse of the Drosophila Hox protein Abdominal-A schedules the end of neural proliferation via neuroblast apoptosis. Neuron 2003; 37:209-19. [PMID: 12546817 DOI: 10.1016/s0896-6273(02)01181-9] [Citation(s) in RCA: 153] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Postembryonic neuroblasts are stem cell-like precursors that generate most neurons of the adult Drosophila central nervous system (CNS). Their capacity to divide is modulated along the anterior-posterior body axis, but the mechanism underlying this is unclear. We use clonal analysis of identified precursors in the abdomen to show that neuron production stops because the cell death program is activated in the neuroblast while it is still engaged in the cell cycle. A burst of expression of the Hox protein Abdominal-A (AbdA) specifies the time at which apoptosis occurs, thereby determining the final number of progeny that each neuroblast generates. These studies identify a mechanism linking the Hox axial patterning system to neural proliferation, and this involves temporal regulation of precursor cell death rather than the cell cycle.
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Affiliation(s)
- Bruno C Bello
- Medical Research Council, National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, United Kingdom
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15
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Köhler C, Grossniklaus U. Epigenetic inheritance of expression states in plant development: the role of Polycomb group proteins. Curr Opin Cell Biol 2002; 14:773-9. [PMID: 12473353 DOI: 10.1016/s0955-0674(02)00394-0] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Polycomb group (PcG) proteins maintain a repressed state of gene expression over many cell divisions. The recent characterisation of several PcG proteins from plants revealed a remarkable structural and functional conservation of PcG proteins between different kingdoms. In both plants and animals, homeotic genes are among the target genes of PcG complexes, although the structure of these genes is not conserved. However, not all PcG proteins identified in animals are present in plants. Furthermore it becomes clear that PcG-mediated repression in plants is more transient compared with the long-lasting effects in animals. This may be related to the absence of PcG proteins thought to be involved in long-term maintenance of PcG repression, suggesting that the mechanisms underlying PcG-mediated repression differ between plants and animals.
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Affiliation(s)
- Claudia Köhler
- Institute of Plant Biology, University of Zürich, Zollikerstrasse 107, CH-8008, Zürich, Switzerland.
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Jacobs JJL, van Lohuizen M. Polycomb repression: from cellular memory to cellular proliferation and cancer. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1602:151-61. [PMID: 12020801 DOI: 10.1016/s0304-419x(02)00052-5] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
The transcriptional repressors of the Polycomb group (PcG), together with the counteracting Trithorax group (TrxG) proteins, establish a form of cellular memory by regulating gene expression in a heritable fashion at the level of chromatin. This cellular memory function is required for a correct cell fate/behavior, which is not only crucial during development for the generation of a correct body plan but also later in life to prevent cellular transformation. Here, we summarize the rapidly accumulating data that implicate several mammalian PcG members in the control of cellular proliferation and tumorigenesis.
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Affiliation(s)
- Jacqueline J L Jacobs
- Department of Molecular Genetics, The Netherlands Cancer Institute, H5, Plesmanlaan 121, Amsterdam, The Netherlands
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17
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Abstract
If the last common ancestor of plants and animals was unicellular, comparison of the developmental mechanisms of plants and animals would show that development was independently invented in each lineage. And if this is the case, comparison of plant and animal developmental processes would give us a truly comparative study of development, which comparisons merely among animals, or merely among plants, do not-because in each of these lineages, the fundamental mechanisms are similar by descent. Evidence from studies of developmental mechanisms in both kingdoms, and data from genome-sequencing projects, indicate that development evolved independently in the lineages leading to plants and to animals.
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Affiliation(s)
- Elliot M Meyerowitz
- Division of Biology 156-29, California Institute of Technology, Pasadena, CA 91125, USA.
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