1
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Kumar R, Evans T. Activation-Induced Cytidine Deaminase Regulates Fibroblast Growth Factor/Extracellular Signal-Regulated Kinases Signaling to Achieve the Naïve Pluripotent State During Reprogramming. Stem Cells 2019; 37:1003-1017. [PMID: 31021461 PMCID: PMC6766926 DOI: 10.1002/stem.3023] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Revised: 03/20/2019] [Accepted: 03/31/2019] [Indexed: 11/12/2022]
Abstract
Induced pluripotent stem cells (iPSCs) derived by in vitro reprogramming of somatic cells retain the capacity to self-renew and to differentiate into many cell types. Pluripotency encompasses multiple states, with naïve iPSCs considered as ground state, possessing high levels of self-renewal capacity and maximum potential without lineage restriction. We showed previously that activation-induced cytidine deaminase (AICDA) facilitates stabilization of pluripotency during reprogramming. Here, we report that Acida-/- iPSCs, even when successfully reprogrammed, fail to achieve the naïve pluripotent state and remain primed for differentiation because of a failure to suppress fibroblast growth factor (FGF)/extracellular signal-regulated kinases (ERK) signaling. Although the mutant cells display marked genomic hypermethylation, suppression of FGF/ERK signaling by AICDA is independent of deaminase activity. Thus, our study identifies AICDA as a novel regulator of naïve pluripotency through its activity on FGF/ERK signaling. Stem Cells 2019;37:1003-1017.
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Affiliation(s)
- Ritu Kumar
- Department of Surgery, Weill Cornell Medicine, New York, New York, USA
| | - Todd Evans
- Department of Surgery, Weill Cornell Medicine, New York, New York, USA
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2
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Nishihara K, Shiga T, Nakamura E, Akiyama T, Sasaki T, Suzuki S, Ko MSH, Tada N, Okano H, Akamatsu W. Induced Pluripotent Stem Cells Reprogrammed with Three Inhibitors Show Accelerated Differentiation Potentials with High Levels of 2-Cell Stage Marker Expression. Stem Cell Reports 2019; 12:305-318. [PMID: 30713040 PMCID: PMC6373546 DOI: 10.1016/j.stemcr.2018.12.018] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Revised: 12/29/2018] [Accepted: 12/30/2018] [Indexed: 02/06/2023] Open
Abstract
Although pluripotent stem cells can generate various types of differentiated cells, it is unclear why lineage-committed stem/progenitor cells derived from pluripotent stem cells are decelerated and why the differentiation-resistant propensity of embryonic stem cell (ESC)/induced pluripotent stem cell (iPSC)-derived cells is predominant compared with the in vivo equivalents derived from embryonic/adult tissues. In this study, we demonstrated that iPSCs reprogrammed and maintained with three chemical inhibitors of the fibroblast growth factor 4-mitogen-activated protein kinase cascade and GSK3β (3i) could be differentiated into all three germ layers more efficiently than the iPSCs reprogrammed without the 3i chemicals, even though they were maintained with 3i chemicals once they were reprogrammed. Although the iPSCs reprogrammed with 3i had increased numbers of Zscan4-positive cells, the Zscan4-positive cells among iPSCs that were reprogrammed without 3i did not have an accelerated differentiation ability. These observations suggest that 3i exposure during the reprogramming period determines the accelerated differentiation/maturation potentials of iPSCs that are stably maintained at the distinct state.
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Affiliation(s)
- Koji Nishihara
- Department of Physiology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan
| | - Takahiro Shiga
- Center for Genomic and Regenerative Medicine, Juntendo University School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan
| | - Eri Nakamura
- Research Institute for Diseases of Old Age, Juntendo University School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan
| | - Tomohiko Akiyama
- Department of Systems Medicine, Sakaguchi Laboratory, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan
| | - Takashi Sasaki
- Center for Supercentenarian Medical Research, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan
| | - Sadafumi Suzuki
- Department of Physiology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan
| | - Minoru S H Ko
- Department of Systems Medicine, Sakaguchi Laboratory, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan
| | - Norihiro Tada
- Research Institute for Diseases of Old Age, Juntendo University School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan
| | - Hideyuki Okano
- Department of Physiology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan.
| | - Wado Akamatsu
- Department of Physiology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan; Center for Genomic and Regenerative Medicine, Juntendo University School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan.
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3
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Hao F, Tian M, Feng Y, Quan C, Chen Y, Chen S, Wei M. Abrogation of Lupus Nephritis in Somatic Hypermutation-Deficient MRL/lpr Mice. THE JOURNAL OF IMMUNOLOGY 2018; 200:3905-3912. [PMID: 29728506 DOI: 10.4049/jimmunol.1800115] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Accepted: 03/31/2018] [Indexed: 01/31/2023]
Abstract
Systemic lupus erythematosus (SLE) is an autoimmune disease posing threats to multiple organs in the human body. As a typical manifestation of SLE, lupus nephritis is characterized by a series of pathological changes in glomerulus as well as accumulation of pathogenic autoreactive IgG with complement in the kidney that dramatically disrupts renal functions. Activation-induced deaminase (AID), which governs both somatic hypermutation (SHM) and class-switch recombination (CSR), has been shown to be essential for the regulation of SLE. However, the relative contributions of SHM and CSR to SLE pathology have not been determined. Based on the available AIDG23S mice, we successfully established an AIDG23S MRL/lpr mouse model, in which SHM is specifically abolished, although CSR is largely unaffected. We found that the abrogation of SHM effectively alleviated SLE-associated histopathological alterations, such as expansion of the mesangial matrix and thickening of the basement membrane of Bowman's capsule as well as infiltration of inflammatory cells. Compared with SLE mice, AIDG23S MRL/lpr mice exhibited decreased proteinuria, blood urea nitrogen, and creatinine, indicating that the loss of SHM contributed to the recovery of renal functions. As a consequence, the life span of those SHM-deficient MRL/lpr mice was extended. Together, we provide direct evidence pinpointing a vital role of SHM in the control of SLE development.
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Affiliation(s)
- Fengqi Hao
- Key Laboratory of Molecular Epigenetics of the Ministry of Education, Northeast Normal University, Changchun, 130024, People's Republic of China.,School of Life Science and Technology, Changchun University of Science and Technology, Changchun, 130022, People's Republic of China; and
| | - Miaomiao Tian
- Key Laboratory of Molecular Epigenetics of the Ministry of Education, Northeast Normal University, Changchun, 130024, People's Republic of China
| | - Yunpeng Feng
- Key Laboratory of Molecular Epigenetics of the Ministry of Education, Northeast Normal University, Changchun, 130024, People's Republic of China
| | - Chao Quan
- Ministry of Education Key Laboratory of Model Animal for Disease Study, State Key Laboratory of Pharmaceutical Biotechnology, Model Animal Research Center, Nanjing University, Nanjing, 210061, People's Republic of China
| | - Yixi Chen
- Key Laboratory of Molecular Epigenetics of the Ministry of Education, Northeast Normal University, Changchun, 130024, People's Republic of China
| | - Shuai Chen
- Ministry of Education Key Laboratory of Model Animal for Disease Study, State Key Laboratory of Pharmaceutical Biotechnology, Model Animal Research Center, Nanjing University, Nanjing, 210061, People's Republic of China
| | - Min Wei
- Key Laboratory of Molecular Epigenetics of the Ministry of Education, Northeast Normal University, Changchun, 130024, People's Republic of China;
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4
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Milagre I, Stubbs TM, King MR, Spindel J, Santos F, Krueger F, Bachman M, Segonds-Pichon A, Balasubramanian S, Andrews SR, Dean W, Reik W. Gender Differences in Global but Not Targeted Demethylation in iPSC Reprogramming. Cell Rep 2017; 18:1079-1089. [PMID: 28147265 PMCID: PMC5300890 DOI: 10.1016/j.celrep.2017.01.008] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Revised: 12/23/2016] [Accepted: 01/06/2017] [Indexed: 01/08/2023] Open
Abstract
Global DNA demethylation is an integral part of reprogramming processes in vivo and in vitro, but whether it occurs in the derivation of induced pluripotent stem cells (iPSCs) is not known. Here, we show that iPSC reprogramming involves both global and targeted demethylation, which are separable mechanistically and by their biological outcomes. Cells at intermediate-late stages of reprogramming undergo transient genome-wide demethylation, which is more pronounced in female cells. Global demethylation requires activation-induced cytidine deaminase (AID)-mediated downregulation of UHRF1 protein, and abolishing demethylation leaves thousands of hypermethylated regions in the iPSC genome. Independently of AID and global demethylation, regulatory regions, particularly ESC enhancers and super-enhancers, are specifically targeted for hypomethylation in association with transcription of the pluripotency network. Our results show that global and targeted DNA demethylation are conserved and distinct reprogramming processes, presumably because of their respective roles in epigenetic memory erasure and in the establishment of cell identity.
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Affiliation(s)
- Inês Milagre
- Epigenetics Programme, The Babraham Institute, Cambridge CB22 3AT, UK.
| | - Thomas M Stubbs
- Epigenetics Programme, The Babraham Institute, Cambridge CB22 3AT, UK
| | - Michelle R King
- Epigenetics Programme, The Babraham Institute, Cambridge CB22 3AT, UK
| | - Julia Spindel
- Epigenetics Programme, The Babraham Institute, Cambridge CB22 3AT, UK
| | - Fátima Santos
- Epigenetics Programme, The Babraham Institute, Cambridge CB22 3AT, UK
| | - Felix Krueger
- Bioinformatics Group, The Babraham Institute, Cambridge CB22 3AT, UK
| | - Martin Bachman
- Department of Chemistry, University of Cambridge, Cambridge CB2 1EW, UK; Cancer Research UK Cambridge Institute, University of Cambridge, Cambridge CB2 0RE, UK
| | | | - Shankar Balasubramanian
- Department of Chemistry, University of Cambridge, Cambridge CB2 1EW, UK; Cancer Research UK Cambridge Institute, University of Cambridge, Cambridge CB2 0RE, UK
| | - Simon R Andrews
- Bioinformatics Group, The Babraham Institute, Cambridge CB22 3AT, UK
| | - Wendy Dean
- Epigenetics Programme, The Babraham Institute, Cambridge CB22 3AT, UK
| | - Wolf Reik
- Epigenetics Programme, The Babraham Institute, Cambridge CB22 3AT, UK; Centre for Trophoblast Research, University of Cambridge, Cambridge CB2 3EG, UK; Wellcome Trust Sanger Institute, Hinxton CB10 1SA, UK.
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5
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Bochtler M, Kolano A, Xu GL. DNA demethylation pathways: Additional players and regulators. Bioessays 2016; 39:1-13. [PMID: 27859411 DOI: 10.1002/bies.201600178] [Citation(s) in RCA: 106] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
DNA demethylation can occur passively by "dilution" of methylation marks by DNA replication, or actively and independently of DNA replication. Direct conversion of 5-methylcytosine (5mC) to cytosine (C), as originally proposed, does not occur. Instead, active DNA methylation involves oxidation of the methylated base by ten-eleven translocations (TETs), or deamination of the methylated or a nearby base by activation induced deaminase (AID). The modified nucleotide, possibly together with surrounding nucleotides, is then replaced by the BER pathway. Recent data clarify the roles and the regulation of well-known enzymes in this process. They identify base excision repair (BER) glycosylases that may cooperate with or replace thymine DNA glycosylase (TDG) in the base excision step, and suggest possible involvement of DNA damage repair pathways other than BER in active DNA demethylation. Here, we review these new developments.
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Affiliation(s)
- Matthias Bochtler
- International Institute of Molecular and Cell Biology, Warsaw, Poland.,Institute of Biochemistry and Biophysics Polish Academy of Sciences, Warsaw, Poland
| | - Agnieszka Kolano
- International Institute of Molecular and Cell Biology, Warsaw, Poland
| | - Guo-Liang Xu
- Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai, China
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6
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Yamakawa T, Sato Y, Matsumura Y, Kobayashi Y, Kawamura Y, Goshima N, Yamanaka S, Okita K. Screening of Human cDNA Library Reveals Two differentiation-Related Genes, HHEX and HLX, as Promoters of Early Phase Reprogramming toward Pluripotency. Stem Cells 2016; 34:2661-2669. [PMID: 27335261 DOI: 10.1002/stem.2436] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Revised: 05/09/2016] [Accepted: 05/30/2016] [Indexed: 11/09/2022]
Abstract
Gene screenings have identified a number of reprogramming factors that induce pluripotency from somatic cells. However, the screening methods have mostly considered only factors that maintain pluripotency in embryonic stem cells, ignoring a potentially long list of other contributing factors involved. To expand the search, we developed a new screening method that examined 2,008 human genes in the generation of human induced pluripotent stem cells (iPSCs), including not only pluripotent genes but also differentiation-related genes that suppress pluripotency. We found the top 100 genes that increased reprogramming efficiency and discovered they contained many differentiation-related genes and homeobox genes. We selected two, HHEX and HLX, for further analysis. These genes enhanced the appearance of premature reprograming cells in the early phase of human iPSC induction, but had inhibitory effect on the late phase. In addition, when expressed in human iPSCs, HHEX and HLX interfered with the pluripotent state, indicating inverse effects on somatic reprograming and pluripotent maintenance. These results demonstrate that our screening is useful for identifying differentiation-related genes in somatic reprograming. Stem Cells 2016;34:2661-2669.
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Affiliation(s)
- Tatsuya Yamakawa
- Center for iPS Cell Research and Application, Kyoto University, Kyoto, Japan
| | - Yoshiko Sato
- Center for iPS Cell Research and Application, Kyoto University, Kyoto, Japan
| | - Yasuko Matsumura
- Center for iPS Cell Research and Application, Kyoto University, Kyoto, Japan
| | - Yukiko Kobayashi
- Center for iPS Cell Research and Application, Kyoto University, Kyoto, Japan
| | | | - Naoki Goshima
- Molecular Profiling Research Center for Drug Discovery, National Institute of Advanced Industrial Science and Technology, Tokyo, Japan
| | - Shinya Yamanaka
- Center for iPS Cell Research and Application, Kyoto University, Kyoto, Japan.,Gladstone Institute of Cardiovascular Disease, San Francisco, California, USA
| | - Keisuke Okita
- Center for iPS Cell Research and Application, Kyoto University, Kyoto, Japan
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7
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Abstract
Chromosomal translocations are a hallmark of cancer. Unraveling the molecular mechanism of these rare genetic events requires a clear distinction between correlative and causative risk-determinants, where technical and analytical issues can be excluded. To meet this goal, we performed in-depth analyses of publicly available genome-wide datasets. In contrast to several recent reports, we demonstrate that chromosomal translocation risk is causally unrelated to promoter stalling (Spt5), transcriptional activity, or off-targeting activity of the activation-induced cytidine deaminase. Rather, an open chromatin configuration, which is not promoter-specific, explained the elevated translocation risk of promoter regions. Furthermore, the fact that gene size directly correlates with the translocation risk in mice and human cancers further demonstrated the general irrelevance of promoter-specific activities. Interestingly, a subset of translocations observed in cancer patients likely initiates from double-strand breaks induced by an access-independent process. Together, these unexpected and novel insights are fundamental in understanding the origin of chromosome translocations and, consequently, cancer.
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8
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Schuermann D, Weber AR, Schär P. Active DNA demethylation by DNA repair: Facts and uncertainties. DNA Repair (Amst) 2016; 44:92-102. [PMID: 27247237 DOI: 10.1016/j.dnarep.2016.05.013] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Pathways that control and modulate DNA methylation patterning in mammalian cells were poorly understood for a long time, although their importance in establishing and maintaining cell type-specific gene expression was well recognized. The discovery of proteins capable of converting 5-methylcytosine (5mC) to putative substrates for DNA repair introduced a novel and exciting conceptual framework for the investigation and ultimate discovery of molecular mechanisms of DNA demethylation. Against the prevailing notion that DNA methylation is a static epigenetic mark, it turned out to be dynamic and distinct mechanisms appear to have evolved to effect global and locus-specific DNA demethylation. There is compelling evidence that DNA repair, in particular base excision repair, contributes significantly to the turnover of 5mC in cells. By actively demethylating DNA, DNA repair supports the developmental establishment as well as the maintenance of DNA methylation landscapes and gene expression patterns. Yet, while the biochemical pathways are relatively well-established and reviewed, the biological context, function and regulation of DNA repair-mediated active DNA demethylation remains uncertain. In this review, we will thus summarize and critically discuss the evidence that associates active DNA demethylation by DNA repair with specific functional contexts including the DNA methylation erasure in the early embryo, the control of pluripotency and cellular differentiation, the maintenance of cell identity, and the nuclear reprogramming.
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Affiliation(s)
- David Schuermann
- Department of Biomedicine, University of Basel, Mattenstrasse 28, CH-4058 Basel, Switzerland
| | - Alain R Weber
- Department of Biomedicine, University of Basel, Mattenstrasse 28, CH-4058 Basel, Switzerland
| | - Primo Schär
- Department of Biomedicine, University of Basel, Mattenstrasse 28, CH-4058 Basel, Switzerland.
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9
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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: 15] [Impact Index Per Article: 1.7] [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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10
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Seifert A, Werheid DF, Knapp SM, Tobiasch E. Role of Hox genes in stem cell differentiation. World J Stem Cells 2015; 7:583-595. [PMID: 25914765 PMCID: PMC4404393 DOI: 10.4252/wjsc.v7.i3.583] [Citation(s) in RCA: 107] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Revised: 11/20/2014] [Accepted: 12/17/2014] [Indexed: 02/06/2023] Open
Abstract
Hox genes are an evolutionary highly conserved gene family. They determine the anterior-posterior body axis in bilateral organisms and influence the developmental fate of cells. Embryonic stem cells are usually devoid of any Hox gene expression, but these transcription factors are activated in varying spatial and temporal patterns defining the development of various body regions. In the adult body, Hox genes are among others responsible for driving the differentiation of tissue stem cells towards their respective lineages in order to repair and maintain the correct function of tissues and organs. Due to their involvement in the embryonic and adult body, they have been suggested to be useable for improving stem cell differentiations in vitro and in vivo. In many studies Hox genes have been found as driving factors in stem cell differentiation towards adipogenesis, in lineages involved in bone and joint formation, mainly chondrogenesis and osteogenesis, in cardiovascular lineages including endothelial and smooth muscle cell differentiations, and in neurogenesis. As life expectancy is rising, the demand for tissue reconstruction continues to increase. Stem cells have become an increasingly popular choice for creating therapies in regenerative medicine due to their self-renewal and differentiation potential. Especially mesenchymal stem cells are used more and more frequently due to their easy handling and accessibility, combined with a low tumorgenicity and little ethical concerns. This review therefore intends to summarize to date known correlations between natural Hox gene expression patterns in body tissues and during the differentiation of various stem cells towards their respective lineages with a major focus on mesenchymal stem cell differentiations. This overview shall help to understand the complex interactions of Hox genes and differentiation processes all over the body as well as in vitro for further improvement of stem cell treatments in future regenerative medicine approaches.
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11
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Correction: Generation and characterization of induced pluripotent stem cells from aid-deficient mice. PLoS One 2015; 10:e0119209. [PMID: 25785711 PMCID: PMC4364784 DOI: 10.1371/journal.pone.0119209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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12
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Ramiro AR, Barreto VM. Activation-induced cytidine deaminase and active DNA demethylation. Trends Biochem Sci 2015; 40:172-81. [PMID: 25661247 DOI: 10.1016/j.tibs.2015.01.006] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Revised: 01/11/2015] [Accepted: 01/12/2015] [Indexed: 12/22/2022]
Abstract
The regulation of demethylation in vertebrates has begun to be elucidated in the past decade. However, a possible involvement of activation-induced cytidine deaminase (AID) in this process remains uncertain. We survey the data supporting or casting doubt on such a role, and propose that there is no strong evidence for an involvement of AID in genome-wide active demethylation processes. Conversely, we present evidence that favors AID involvement in gene-specific demethylation events underlying cell differentiation.
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Affiliation(s)
- Almudena R Ramiro
- B Cell Biology Lab, Centro Nacional de Investigaciones Cardiovasculares (CNIC), Calle de Melchor Fernandez Almagro 3, 28029 Madrid, Spain
| | - Vasco M Barreto
- Instituto Gulbenkian de Ciência, Rua da Quinta Grande 6, Oeiras, Portugal.
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13
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Dominguez PM, Shaknovich R. Epigenetic function of activation-induced cytidine deaminase and its link to lymphomagenesis. Front Immunol 2014; 5:642. [PMID: 25566255 PMCID: PMC4270259 DOI: 10.3389/fimmu.2014.00642] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2014] [Accepted: 12/02/2014] [Indexed: 01/16/2023] Open
Abstract
Activation-induced cytidine deaminase (AID) is essential for somatic hypermutation and class switch recombination of immunoglobulin (Ig) genes during B cell maturation and immune response. Expression of AID is tightly regulated due to its mutagenic and recombinogenic potential, which is known to target not only Ig genes, but also non-Ig genes, contributing to lymphomagenesis. In recent years, a new epigenetic function of AID and its link to DNA demethylation came to light in several developmental systems. In this review, we summarize existing evidence linking deamination of unmodified and modified cytidine by AID to base-excision repair and mismatch repair machinery resulting in passive or active removal of DNA methylation mark, with the focus on B cell biology. We also discuss potential contribution of AID-dependent DNA hypomethylation to lymphomagenesis.
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Affiliation(s)
- Pilar M Dominguez
- Division of Hematology and Oncology, Weill Cornell Medical College , New York, NY , USA
| | - Rita Shaknovich
- Division of Hematology and Oncology, Weill Cornell Medical College , New York, NY , USA ; Department of Pathology and Laboratory Medicine, Weill Cornell Medical College , New York, NY , USA
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14
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The pluripotency transcription factor network at work in reprogramming. Curr Opin Genet Dev 2014; 28:25-31. [DOI: 10.1016/j.gde.2014.08.004] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2014] [Revised: 08/12/2014] [Accepted: 08/12/2014] [Indexed: 11/18/2022]
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15
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Abstract
Deciphering the mechanisms of epigenetic reprogramming provides fundamental insights into cell fate decisions, which in turn reveal strategies to make the reprogramming process increasingly efficient. Here we review recent advances in epigenetic reprogramming to pluripotency with a focus on the principal molecular regulators. We examine the trajectories connecting somatic and pluripotent cells, genetic and chemical methodologies for inducing pluripotency, the role of endogenous master transcription factors in establishing the pluripotent state, and functional interactions between reprogramming factors and epigenetic regulators. Defining the crosstalk among the diverse molecular actors implicated in cellular reprogramming presents a major challenge for future inquiry.
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Affiliation(s)
| | - Rudolf Jaenisch
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA; Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142, USA.
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