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Timing of transcription during the cell cycle: Protein complexes binding to E2F, E2F/CLE, CDE/CHR, or CHR promoter elements define early and late cell cycle gene expression. Oncotarget 2016; 8:97736-97748. [PMID: 29228647 PMCID: PMC5716687 DOI: 10.18632/oncotarget.10888] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Accepted: 06/28/2016] [Indexed: 12/20/2022] Open
Abstract
A central question in cell cycle control is how differential gene expression is regulated. Timing of expression is important for correct progression through the cell cycle. E2F, CDE, and CHR promoter sites have been linked to transcriptional repression in resting cells and activation during the cell cycle. Further, the DREAM complex binds CHR or CDE/CHR elements of G2/M genes resulting in repression during G0/G1. Here, we show that DREAM also binds to E2F sites of S phase genes in quiescence and upon p53 activation. Furthermore, we describe a novel class of promoter sites, the CHR-like elements (CLE), which can support binding of DREAM to E2F elements. Activation of such S phase genes is achieved through binding of E2F1-3/DP complexes to E2F sites. In contrast, the activating MuvB complexes MMB and FOXM1-MuvB bind to CHR elements and mediate peak expression in G2/M. In conclusion, data presented here in combination with earlier results leads us to propose a model that explains how DREAM can repress early cell cycle genes through E2F or E2F/CLE sites and late genes through CHR or CDE/CHR elements. Also p53-dependent indirect transcriptional repression through the p53-p21-Cyclin/CDK-DREAM-E2F/CLE/CDE/CHR pathway requires DREAM binding to E2F or E2F/CLE sites in early cell cycle genes and binding of DREAM to CHR or CDE/CHR elements of late cell cycle genes. Specific timing of activation is achieved through binding of E2F1-3/DP to E2F sites and MMB or FOXM1-MuvB complexes to CHR elements.
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Abstract
The dimerization partner, RB-like, E2F and multi-vulval class B (DREAM) complex provides a previously unsuspected unifying role in the cell cycle by directly linking p130, p107, E2F, BMYB and forkhead box protein M1. DREAM mediates gene repression during the G0 phase and coordinates periodic gene expression with peaks during the G1/S and G2/M phases. Perturbations in DREAM complex regulation shift the balance from quiescence towards proliferation and contribute to the increased mitotic gene expression levels that are frequently observed in cancers with a poor prognosis.
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Affiliation(s)
- Subhashini Sadasivam
- Institute for Stem Cell Biology and Regenerative Medicine National Centre for Biological Sciences (TIFR), Bellary Road, Bangalore 560065, India
| | - James A. DeCaprio
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston MA 02215 USA Department of Medicine, Brigham and Women's Hospital, Boston MA 02115 USA Department of Medicine, Harvard Medical School, Boston, MA 02115 USA
- Corresponding author James A. DeCaprio Dana-Farber Cancer Institute 450 Brookline Avenue Boston, MA 02215 Tel: 617-632-3825 Fax: 617-582-8601
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Abstract
The dimerization partner, RB-like, E2F and multi-vulval class B (DREAM) complex provides a previously unsuspected unifying role in the cell cycle by directly linking p130, p107, E2F, BMYB and forkhead box protein M1. DREAM mediates gene repression during the G0 phase and coordinates periodic gene expression with peaks during the G1/S and G2/M phases. Perturbations in DREAM complex regulation shift the balance from quiescence towards proliferation and contribute to the increased mitotic gene expression levels that are frequently observed in cancers with a poor prognosis.
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Zhan M, Riordon DR, Yan B, Tarasova YS, Bruweleit S, Tarasov KV, Li RA, Wersto RP, Boheler KR. The B-MYB transcriptional network guides cell cycle progression and fate decisions to sustain self-renewal and the identity of pluripotent stem cells. PLoS One 2012; 7:e42350. [PMID: 22936984 PMCID: PMC3427317 DOI: 10.1371/journal.pone.0042350] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2012] [Accepted: 07/04/2012] [Indexed: 01/08/2023] Open
Abstract
Embryonic stem cells (ESCs) are pluripotent and have unlimited self-renewal capacity. Although pluripotency and differentiation have been examined extensively, the mechanisms responsible for self-renewal are poorly understood and are believed to involve an unusual cell cycle, epigenetic regulators and pluripotency-promoting transcription factors. Here we show that B-MYB, a cell cycle regulated phosphoprotein and transcription factor critical to the formation of inner cell mass, is central to the transcriptional and co-regulatory networks that sustain normal cell cycle progression and self-renewal properties of ESCs. Phenotypically, B-MYB is robustly expressed in ESCs and induced pluripotent stem cells (iPSCs), and it is present predominantly in a hypo-phosphorylated state. Knockdown of B-MYB results in functional cell cycle abnormalities that involve S, G2 and M phases, and reduced expression of critical cell cycle regulators like ccnb1 and plk1. By conducting gene expression profiling on control and B-MYB deficient cells, ChIP-chip experiments, and integrative computational analyses, we unraveled a highly complex B-MYB-mediated transcriptional network that guides ESC self-renewal. The network encompasses critical regulators of all cell cycle phases and epigenetic regulators, pluripotency transcription factors, and differentiation determinants. B-MYB along with E2F1 and c-MYC preferentially co-regulate cell cycle target genes. B-MYB also co-targets genes regulated by OCT4, SOX2 and NANOG that are significantly associated with stem cell differentiation, embryonic development, and epigenetic control. Moreover, loss of B-MYB leads to a breakdown of the transcriptional hierarchy present in ESCs. These results coupled with functional studies demonstrate that B-MYB not only controls and accelerates cell cycle progression in ESCs it contributes to fate decisions and maintenance of pluripotent stem cell identity.
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Affiliation(s)
- Ming Zhan
- Bioinformatics Unit, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, United States of America
- The Methodist Hospital Research Institute, Cornell University Weill Cornell Medical College, Houston, Texas, United States of America
| | - Daniel R. Riordon
- Molecular Cardiology and Stem Cell Unit, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, United States of America
| | - Bin Yan
- Bioinformatics Unit, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, United States of America
- Department of Biology, Hong Kong Baptist University, Hong Kong, China
| | - Yelena S. Tarasova
- Molecular Cardiology and Stem Cell Unit, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, United States of America
| | - Sarah Bruweleit
- Molecular Cardiology and Stem Cell Unit, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, United States of America
| | - Kirill V. Tarasov
- Molecular Cardiology and Stem Cell Unit, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, United States of America
| | - Ronald A. Li
- Stem Cell and Regenerative Medicine Consortium, LKS Faculty of Medicine, University of Hong Kong, Hong Kong, China
| | - Robert P. Wersto
- Flow Cytometry Unit, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, United States of America
| | - Kenneth R. Boheler
- Molecular Cardiology and Stem Cell Unit, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, United States of America
- Stem Cell and Regenerative Medicine Consortium, LKS Faculty of Medicine, University of Hong Kong, Hong Kong, China
- * E-mail:
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Abstract
The transcription factor MYB has a key role as a regulator of stem and progenitor cells in the bone marrow, colonic crypts and a neurogenic region of the adult brain. It is in these compartments that a deficit in MYB activity leads to severe or lethal phenotypes. As was predicted from its leukaemogenicity in several animal species, MYB has now been identified as an oncogene that is involved in some human leukaemias. Moreover, recent evidence has strengthened the case that MYB is activated in colon and breast cancer: a block to MYB expression is overcome by mutation of the regulatory machinery in the former disease and by oestrogen receptor-alpha (ERalpha) in the latter.
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Affiliation(s)
- Robert G Ramsay
- Peter MacCallum Cancer Centre, St Andrew's Place, Melbourne, Victoria 3002, Australia
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