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Krause MN, Sancho-Martinez I, Izpisua Belmonte JC. Understanding the molecular mechanisms of reprogramming. Biochem Biophys Res Commun 2015; 473:693-7. [PMID: 26655812 DOI: 10.1016/j.bbrc.2015.11.120] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Accepted: 11/25/2015] [Indexed: 12/28/2022]
Abstract
Despite the profound and rapid advancements in reprogramming technologies since the generation of the first induced pluripotent stem cells (iPSCs) in 2006[1], the molecular basics of the process and its implications are still not fully understood. Recent work has suggested that a subset of TFs, so called "Pioneer TFs", play an important role during the stochastic phase of iPSC reprogramming [2-6]. Pioneer TFs activities differ from conventional transcription factors in their mechanism of action. They bind directly to condensed chromatin and elicit a series of chromatin remodeling events that lead to opening of the chromatin. Chromatin decondensation by pioneer factors progressively occurs during cell division and in turn exposes specific gene promoters in the DNA to which TFs can now directly bind to promoters that are readily accessible[2, 6]. Here, we will summarize recent advancements on our understanding of the molecular mechanisms underlying reprogramming to iPSC as well as the implications that pioneer Transcription Factor activities might play during different lineage conversion processes.
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Affiliation(s)
- Marie N Krause
- Gene Expression Laboratory, Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla 92037, CA, USA; University Hospital of Würzburg, Department of Pediatrics, 2 Josef-Schneiderstrasse, 97080 Würzburg, Germany
| | - Ignacio Sancho-Martinez
- Gene Expression Laboratory, Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla 92037, CA, USA; Centre for Stem Cells and Regenerative Medicine, King's College London, 28th Floor, Tower Wing, Guy's Hospital, Great Maze Pond, London, UK
| | - Juan Carlos Izpisua Belmonte
- Gene Expression Laboratory, Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla 92037, CA, USA.
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104
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Ebrahimi B. Reprogramming barriers and enhancers: strategies to enhance the efficiency and kinetics of induced pluripotency. CELL REGENERATION (LONDON, ENGLAND) 2015; 4:10. [PMID: 26566431 PMCID: PMC4642739 DOI: 10.1186/s13619-015-0024-9] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/25/2015] [Accepted: 09/19/2015] [Indexed: 12/13/2022]
Abstract
Induced pluripotent stem cells are powerful tools for disease modeling, drug screening, and cell transplantation therapies. These cells can be generated directly from somatic cells by ectopic expression of defined factors through a reprogramming process. However, pluripotent reprogramming is an inefficient process because of various defined and unidentified barriers. Recent studies dissecting the molecular mechanisms of reprogramming have methodically improved the quality, ease, and efficiency of reprogramming. Different strategies have been applied for enhancing reprogramming efficiency, including depletion/inhibition of barriers (p53, p21, p57, p16(Ink4a)/p19(Arf), Mbd3, etc.), overexpression of enhancing genes (e.g., FOXH1, C/EBP alpha, UTF1, and GLIS1), and administration of certain cytokines and small molecules. The current review provides an in-depth overview of the cutting-edge findings regarding distinct barriers of reprogramming to pluripotency and strategies to enhance reprogramming efficiency. By incorporating the mechanistic insights from these recent findings, a combined method of inhibition of roadblocks and application of enhancing factors may yield the most reliable and effective approach in pluripotent reprogramming.
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Affiliation(s)
- Behnam Ebrahimi
- Yazd Cardiovascular Research Center, Shahid Sadoughi University of Medical Sciences, Yazd, Iran
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105
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Daniel MG, Pereira CF, Lemischka IR, Moore KA. Making a Hematopoietic Stem Cell. Trends Cell Biol 2015; 26:202-214. [PMID: 26526106 DOI: 10.1016/j.tcb.2015.10.002] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Revised: 09/29/2015] [Accepted: 10/01/2015] [Indexed: 12/22/2022]
Abstract
Previous attempts to either generate or expand hematopoietic stem cells (HSCs) in vitro have involved either ex vivo expansion of pre-existing patient or donor HSCs or de novo generation from pluripotent stem cells (PSCs), comprising both embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs). iPSCs alleviated ESC ethical issues but attempts to generate functional mature hematopoietic stem and progenitor cells (HSPCs) have been largely unsuccessful. New efforts focus on directly reprogramming somatic cells into definitive HSCs and HSPCs. To meet clinical needs and to advance drug discovery and stem cell therapy, alternative approaches are necessary. In this review, we synthesize the strategies used and the key findings made in recent years by those trying to make an HSC.
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Affiliation(s)
- Michael G Daniel
- Department of Developmental and Regenerative Biology, Icahn School of Medicine, New York, NY, USA; Black Family Stem Cell Institute, Icahn School of Medicine, New York, NY, USA; The Graduate School of Biomedical Science, Icahn School of Medicine, New York, NY, USA
| | - Carlos-Filipe Pereira
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra, UC Biotech Building, Biocant Park, 3060-197 Cantanhede, Portugal
| | - Ihor R Lemischka
- Department of Developmental and Regenerative Biology, Icahn School of Medicine, New York, NY, USA; Black Family Stem Cell Institute, Icahn School of Medicine, New York, NY, USA; Department of Pharmacology and Systems Therapeutics, Icahn School of Medicine, New York, NY, USA
| | - Kateri A Moore
- Department of Developmental and Regenerative Biology, Icahn School of Medicine, New York, NY, USA; Black Family Stem Cell Institute, Icahn School of Medicine, New York, NY, USA.
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107
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González F, Huangfu D. Mechanisms underlying the formation of induced pluripotent stem cells. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2015; 5:39-65. [PMID: 26383234 DOI: 10.1002/wdev.206] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2015] [Revised: 07/13/2015] [Accepted: 07/21/2015] [Indexed: 12/19/2022]
Abstract
Human pluripotent stem cells (hPSCs) offer unique opportunities for studying human biology, modeling diseases, and therapeutic applications. The simplest approach so far to generate human PSC lines is through reprogramming of somatic cells from an individual by defined factors, referred to simply as reprogramming. Reprogramming circumvents the ethical controversies associated with human embryonic stem cells (hESCs) and nuclear transfer hESCs (nt-hESCs), and the resulting induced pluripotent stem cells (hiPSCs) retain the same basic genetic makeup as the somatic cell used for reprogramming. Since the first report of iPSCs by Takahashi and Yamanaka (Cell 2006, 126:663-676), the molecular mechanisms of reprogramming have been extensively investigated. A better mechanistic understanding of reprogramming is fundamental not only to iPSC biology and improving the quality of iPSCs for therapeutic use, but also to our understanding of the molecular basis of cell identity, pluripotency, and plasticity. Here, we summarize the genetic, epigenetic, and cellular events during reprogramming, and the roles of various factors identified thus far in the reprogramming process. WIREs Dev Biol 2016, 5:39-65. doi: 10.1002/wdev.206 For further resources related to this article, please visit the WIREs website.
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Affiliation(s)
- Federico González
- Developmental Biology Program, Sloan-Kettering Institute, New York, NY, USA
| | - Danwei Huangfu
- Developmental Biology Program, Sloan-Kettering Institute, New York, NY, USA
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109
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Doppler SA, Deutsch MA, Lange R, Krane M. Direct Reprogramming-The Future of Cardiac Regeneration? Int J Mol Sci 2015; 16:17368-93. [PMID: 26230692 PMCID: PMC4581198 DOI: 10.3390/ijms160817368] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Revised: 07/17/2015] [Accepted: 07/22/2015] [Indexed: 12/12/2022] Open
Abstract
Today, the only available curative therapy for end stage congestive heart failure (CHF) is heart transplantation. This therapeutic option is strongly limited by declining numbers of available donor hearts and by restricted long-term performance of the transplanted graft. The disastrous prognosis for CHF with its restricted therapeutic options has led scientists to develop different concepts of alternative regenerative treatment strategies including stem cell transplantation or stimulating cell proliferation of different cardiac cell types in situ. However, first clinical trials with overall inconsistent results were not encouraging, particularly in terms of functional outcome. Among other approaches, very promising ongoing pre-clinical research focuses on direct lineage conversion of scar fibroblasts into functional myocardium, termed “direct reprogramming” or “transdifferentiation.” This review seeks to summarize strategies for direct cardiac reprogramming including the application of different sets of transcription factors, microRNAs, and small molecules for an efficient generation of cardiomyogenic cells for regenerative purposes.
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Affiliation(s)
- Stefanie A Doppler
- Division of Experimental Surgery, Department of Cardiovascular Surgery, Deutsches Herzzentrum München, Technische Universität München (TUM), Munich 80636, Germany.
| | - Marcus-André Deutsch
- Division of Experimental Surgery, Department of Cardiovascular Surgery, Deutsches Herzzentrum München, Technische Universität München (TUM), Munich 80636, Germany.
| | - Rüdiger Lange
- Division of Experimental Surgery, Department of Cardiovascular Surgery, Deutsches Herzzentrum München, Technische Universität München (TUM), Munich 80636, Germany.
- DZHK (German Center for Cardiovascular Research)-Partner Site Munich Heart Alliance, Munich 80802, Germany.
| | - Markus Krane
- Division of Experimental Surgery, Department of Cardiovascular Surgery, Deutsches Herzzentrum München, Technische Universität München (TUM), Munich 80636, Germany.
- DZHK (German Center for Cardiovascular Research)-Partner Site Munich Heart Alliance, Munich 80802, Germany.
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110
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Bar-Nur O, Verheul C, Sommer AG, Brumbaugh J, Schwarz BA, Lipchina I, Huebner AJ, Mostoslavsky G, Hochedlinger K. Lineage conversion induced by pluripotency factors involves transient passage through an iPSC stage. Nat Biotechnol 2015; 33:761-8. [PMID: 26098450 PMCID: PMC4840929 DOI: 10.1038/nbt.3247] [Citation(s) in RCA: 92] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Accepted: 04/16/2015] [Indexed: 02/07/2023]
Abstract
Brief expression of pluripotency-associated factors such as Oct4, Klf4, Sox2 and c-Myc (OKSM), in combination with differentiation-inducing signals, has been reported to trigger transdifferentiation of fibroblasts into other cell types. Here we show that OKSM expression in mouse fibroblasts gives rise to both induced pluripotent stem cells (iPSCs) and induced neural stem cells (iNSCs) under conditions previously shown to induce only iNSCs. Fibroblast-derived iNSC colonies silenced retroviral transgenes and reactivated silenced X chromosomes, both hallmarks of pluripotent stem cells. Moreover, lineage tracing with an Oct4-CreER labeling system demonstrated that virtually all iNSC colonies originated from cells transiently expressing Oct4, whereas ablation of Oct4(+) cells prevented iNSC formation. Lastly, an alternative transdifferentiation cocktail that lacks Oct4 and was reportedly unable to support induced pluripotency yielded iPSCs and iNSCs carrying the Oct4-CreER-derived lineage label. Together, these data suggest that iNSC generation from fibroblasts using OKSM and other pluripotency-related reprogramming factors requires passage through a transient iPSC state.
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Affiliation(s)
- Ori Bar-Nur
- 1] Center for Regenerative Medicine, Massachusetts General Hospital, Boston, Massachusetts, USA. [2] Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts, USA. [3] Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, Massachusetts, USA. [4] Howard Hughes Medical Institute, Chevy Chase, Maryland, USA. [5] Harvard Stem Cell Institute, Cambridge, Massachusetts, USA
| | - Cassandra Verheul
- 1] Center for Regenerative Medicine, Massachusetts General Hospital, Boston, Massachusetts, USA. [2] Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts, USA. [3] Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, Massachusetts, USA. [4] Howard Hughes Medical Institute, Chevy Chase, Maryland, USA. [5] Harvard Stem Cell Institute, Cambridge, Massachusetts, USA
| | - Andreia G Sommer
- 1] Center for Regenerative Medicine (CReM), Boston University School of Medicine, Boston, Massachusetts, USA. [2] Boston Medical Center, Boston, Massachusetts, USA
| | - Justin Brumbaugh
- 1] Center for Regenerative Medicine, Massachusetts General Hospital, Boston, Massachusetts, USA. [2] Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts, USA. [3] Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, Massachusetts, USA. [4] Howard Hughes Medical Institute, Chevy Chase, Maryland, USA. [5] Harvard Stem Cell Institute, Cambridge, Massachusetts, USA
| | - Benjamin A Schwarz
- 1] Center for Regenerative Medicine, Massachusetts General Hospital, Boston, Massachusetts, USA. [2] Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts, USA. [3] Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, Massachusetts, USA. [4] Howard Hughes Medical Institute, Chevy Chase, Maryland, USA. [5] Harvard Stem Cell Institute, Cambridge, Massachusetts, USA
| | - Inna Lipchina
- 1] Center for Regenerative Medicine, Massachusetts General Hospital, Boston, Massachusetts, USA. [2] Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts, USA. [3] Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, Massachusetts, USA. [4] Howard Hughes Medical Institute, Chevy Chase, Maryland, USA. [5] Harvard Stem Cell Institute, Cambridge, Massachusetts, USA
| | - Aaron J Huebner
- 1] Center for Regenerative Medicine, Massachusetts General Hospital, Boston, Massachusetts, USA. [2] Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts, USA. [3] Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, Massachusetts, USA. [4] Howard Hughes Medical Institute, Chevy Chase, Maryland, USA. [5] Harvard Stem Cell Institute, Cambridge, Massachusetts, USA
| | - Gustavo Mostoslavsky
- 1] Center for Regenerative Medicine (CReM), Boston University School of Medicine, Boston, Massachusetts, USA. [2] Boston Medical Center, Boston, Massachusetts, USA
| | - Konrad Hochedlinger
- 1] Center for Regenerative Medicine, Massachusetts General Hospital, Boston, Massachusetts, USA. [2] Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts, USA. [3] Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, Massachusetts, USA. [4] Howard Hughes Medical Institute, Chevy Chase, Maryland, USA. [5] Harvard Stem Cell Institute, Cambridge, Massachusetts, USA
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