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Tichy ED. Specialized Circuitry of Embryonic Stem Cells Promotes Genomic Integrity. Crit Rev Oncog 2023; 27:1-15. [PMID: 36734869 DOI: 10.1615/critrevoncog.2022042332] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Embryonic stem cells (ESCs) give rise to all cell types of the organism. Given the importance of these cells in this process, ESCs must employ robust mechanisms to protect genomic integrity or risk catastrophic propagation of mutations throughout the organism. Should such an event occur in daughter cells that will eventually contribute to the germline, the overall species health could dramatically decline. This review describes several key mechanisms employed by ESCs that are unique to these cells, in order to maintain their genomic integrity. Additionally, the contributions of cell cycle regulators in modulating ESC differentiation, after DNA damage exposure, are also examined. Where data are available, findings reported in ESCs are extended to include observations described in induced pluripotent stem cells (IPSCs).
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Affiliation(s)
- Elisia D Tichy
- Department of Orthopaedic Surgery, Perelman School of Medicine, The University of Pennsylvania, 371 Stemmler Hall, 3450 Hamilton Walk, Philadelphia, PA 19104-6081
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2
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Park JC, Jang HK, Kim J, Han JH, Jung Y, Kim K, Bae S, Cha HJ. High expression of uracil DNA glycosylase determines C to T substitution in human pluripotent stem cells. MOLECULAR THERAPY. NUCLEIC ACIDS 2022; 27:175-183. [PMID: 34976436 PMCID: PMC8688811 DOI: 10.1016/j.omtn.2021.11.023] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Accepted: 11/28/2021] [Indexed: 10/29/2022]
Abstract
Precise genome editing of human pluripotent stem cells (hPSCs) is crucial not only for basic science but also for biomedical applications such as ex vivo stem cell therapy and genetic disease modeling. However, hPSCs have unique cellular properties compared to somatic cells. For instance, hPSCs are extremely susceptible to DNA damage, and therefore Cas9-mediated DNA double-strand breaks (DSB) induce p53-dependent cell death, resulting in low Cas9 editing efficiency. Unlike Cas9 nucleases, base editors including cytosine base editor (CBE) and adenine base editor (ABE) can efficiently substitute single nucleotides without generating DSBs at target sites. Here, we found that the editing efficiency of CBE was significantly lower than that of ABE in human embryonic stem cells (hESCs), which are associated with high expression of DNA glycosylases, the key component of the base excision repair pathway. Sequential depletion of DNA glycosylases revealed that high expression of uracil DNA glycosylase (UNG) not only resulted in low editing efficiency but also affected CBE product purity (i.e., C to T) in hESCs. Therefore, additional suppression of UNG via transient knockdown would also improve C to T base substitutions in hESCs. These data suggest that the unique cellular characteristics of hPSCs could determine the efficiency of precise genome editing.
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Affiliation(s)
- Ju-Chan Park
- College of Pharmacy, Seoul National University, 1, Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea
| | - Hyeon-Ki Jang
- Institute for Convergence of Basic Sciences, Hanyang University, Seoul 04763, Republic of Korea
| | - Jumee Kim
- College of Pharmacy, Seoul National University, 1, Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea
| | - Jun Hee Han
- Department of Chemistry, Hanyang University, 222, Wangsimni-ro, Seongdong-gu, Seoul 04763, Republic of Korea
| | - Youngri Jung
- Department of Chemistry, Hanyang University, 222, Wangsimni-ro, Seongdong-gu, Seoul 04763, Republic of Korea
| | - Keuntae Kim
- College of Pharmacy, Seoul National University, 1, Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea
| | - Sangsu Bae
- Institute for Convergence of Basic Sciences, Hanyang University, Seoul 04763, Republic of Korea
- Department of Chemistry, Hanyang University, 222, Wangsimni-ro, Seongdong-gu, Seoul 04763, Republic of Korea
| | - Hyuk-Jin Cha
- College of Pharmacy, Seoul National University, 1, Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea
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3
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Munisha M, Schimenti JC. Genome maintenance during embryogenesis. DNA Repair (Amst) 2021; 106:103195. [PMID: 34358805 DOI: 10.1016/j.dnarep.2021.103195] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Revised: 07/26/2021] [Accepted: 07/27/2021] [Indexed: 12/25/2022]
Abstract
Genome maintenance during embryogenesis is critical, because defects during this period can be perpetuated and thus have a long-term impact on individual's health and longevity. Nevertheless, genome instability is normal during certain aspects of embryonic development, indicating that there is a balance between the exigencies of timely cell proliferation and mutation prevention. In particular, early embryos possess unique cellular and molecular features that underscore the challenge of having an appropriate balance. Here, we discuss genome instability during embryonic development, the mechanisms used in various cell compartments to manage genomic stress and address outstanding questions regarding the balance between genome maintenance mechanisms in key cell types that are important for adulthood and progeny.
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Affiliation(s)
- Mumingjiang Munisha
- Dept. of Biomedical Sciences, Cornell University College of Veterinary Medicine, Ithaca, NY 14853, United States
| | - John C Schimenti
- Dept. of Biomedical Sciences, Cornell University College of Veterinary Medicine, Ithaca, NY 14853, United States.
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4
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Rebuzzini P, Civello C, Nantia Akono E, Fassina L, Zuccotti M, Garagna S. Chronic cypermethrin exposure alters mouse embryonic stem cell growth kinetics, induces Phase II detoxification response and affects pluripotency and differentiation gene expression. Eur J Histochem 2020; 64. [PMID: 32214279 PMCID: PMC7036707 DOI: 10.4081/ejh.2020.3084] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Accepted: 02/05/2020] [Indexed: 12/21/2022] Open
Abstract
Worldwide uncontrolled use of synthetic pyrethroids contaminates water and soil leading to health hazards. Cypermethrin (CYP), the most used pyrethroid, induces detrimental effects on adults and embryos at different stages of development of several vertebrate species. In Mammals, CYP-induced alterations have been previously described in adult somatic cells and in post-implantation embryos. It remains unknown whether CYP has effects during pre-implantation development. Studies to access pre-implantation embryo toxicity are complicated by the restricted number of blastocysts that may be obtained, either in vivo or in vitro. Embryonic stem cells (ESCs) are an in vitro model study that overcomes these limitations, as millions of pluripotent cells are available to the analysis. Also, ESCs maintain the same pluripotency characteristics and differentiation capacity of the inner cell mass (ICM) present in the blastocyst, from which they derive. In this work, using mouse R1 ESCs, we studied CYP-induced cell death, ROS production, the activation of oxidative stress-related and detoxification responses and the population growth kinetics following 72 h exposure at the 0.3 mM LD50 dose. Also, the expression levels of pluripotency genes in exposed ESCs and of markers of the three germ layers after their differentiation into embryoid bodies (EBs) were determined. Two apoptotic waves were observed at 12-24 h and at 72 h. The increase of ROS production, at 24 h until the end of the culture period, was accompanied by the induction, at 48 h, of redox-related Cat, Sod1, Sod2, Gpx1 and Gpx4 genes. Up-regulation of Cyp1b1, but not of Cyp1a1, phase I gene was detected at 72 h and induction of Nqo1, Gsta1 and Ugt1a6 phase II genes began at 24 h exposure. The results show that exposed R1 ESCs activate oxidative stress-related and detoxification responses, although not sufficient, during the culture period tested, to warrant recovery of the growth rate observed in untreated cells. Also, CYP exposure altered the expression of Oct-4 and Nanog pluripotency genes in ESCs and, when differentiated into EBs, the expression of Fgf5, Brachyury and Foxa2, early markers of the ectoderm, mesoderm and endoderm germ layers, respectively. NIH/3T3 cells, a differentiated cell line of embryonic origin, were used for comparison.
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Affiliation(s)
- Paola Rebuzzini
- Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia.
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5
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Solari C, Petrone MV, Toro A, Vazquez Echegaray C, Cosentino MS, Waisman A, Francia M, Barañao L, Miriuka S, Guberman A. The pluripotency transcription factor Nanog represses glutathione reductase gene expression in mouse embryonic stem cells. BMC Res Notes 2019; 12:370. [PMID: 31262352 PMCID: PMC6604252 DOI: 10.1186/s13104-019-4411-0] [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: 05/02/2019] [Accepted: 06/26/2019] [Indexed: 01/23/2023] Open
Abstract
OBJECTIVE Redox homeostasis maintenance is essential to bring about cellular functions. Particularly, embryonic stem cells (ESCs) have high fidelity mechanisms for DNA repair, high activity of different antioxidant enzymes and low levels of oxidative stress. Although the expression and activity of antioxidant enzymes are reduced throughout the differentiation, the knowledge about the transcriptional regulation of genes involved in defense against oxidative stress is yet restricted. Since glutathione is a central component of a complex system involved in preserving cellular redox status, we aimed to study whether the expression of the glutathione reductase (Gsr) gene, which encodes an essential enzyme for cellular redox homeostasis, is modulated by the transcription factors critical for self-renewal and pluripotency of ESCs. RESULTS We found that Gsr gene is expressed in ESCs during the pluripotent state and it was upregulated when these cells were induced to differentiate, concomitantly with Nanog decreased expression. Moreover, we found an increase in Gsr mRNA levels when Nanog was downregulated by a specific shRNA targeting this transcription factor in ESCs. Our results suggest that Nanog represses Gsr gene expression in ESCs, evidencing a role of this crucial pluripotency transcription factor in preservation of redox homeostasis in stem cells.
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Affiliation(s)
- Claudia Solari
- Departamento de Química Biológica/Laboratorio de Regulación Génica en Células Madre, Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Buenos Aires, Argentina.,Instituto de Química Biológica (IQUIBICEN), CONICET - Universidad de Buenos Aires, Intendente Guiraldes 2160, Ciudad Universitaria, Pab. 2, 4to piso, QB-71, Buenos Aires, Argentina
| | - María Victoria Petrone
- Departamento de Química Biológica/Laboratorio de Regulación Génica en Células Madre, Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Buenos Aires, Argentina.,Instituto de Química Biológica (IQUIBICEN), CONICET - Universidad de Buenos Aires, Intendente Guiraldes 2160, Ciudad Universitaria, Pab. 2, 4to piso, QB-71, Buenos Aires, Argentina
| | - Ayelén Toro
- Departamento de Química Biológica/Laboratorio de Regulación Génica en Células Madre, Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Buenos Aires, Argentina.,Instituto de Química Biológica (IQUIBICEN), CONICET - Universidad de Buenos Aires, Intendente Guiraldes 2160, Ciudad Universitaria, Pab. 2, 4to piso, QB-71, Buenos Aires, Argentina
| | - Camila Vazquez Echegaray
- Departamento de Química Biológica/Laboratorio de Regulación Génica en Células Madre, Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Buenos Aires, Argentina.,Instituto de Química Biológica (IQUIBICEN), CONICET - Universidad de Buenos Aires, Intendente Guiraldes 2160, Ciudad Universitaria, Pab. 2, 4to piso, QB-71, Buenos Aires, Argentina
| | - María Soledad Cosentino
- Departamento de Química Biológica/Laboratorio de Regulación Génica en Células Madre, Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Buenos Aires, Argentina.,Instituto de Química Biológica (IQUIBICEN), CONICET - Universidad de Buenos Aires, Intendente Guiraldes 2160, Ciudad Universitaria, Pab. 2, 4to piso, QB-71, Buenos Aires, Argentina
| | - Ariel Waisman
- Departamento de Química Biológica/Laboratorio de Regulación Génica en Células Madre, Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Buenos Aires, Argentina.,Instituto de Química Biológica (IQUIBICEN), CONICET - Universidad de Buenos Aires, Intendente Guiraldes 2160, Ciudad Universitaria, Pab. 2, 4to piso, QB-71, Buenos Aires, Argentina
| | - Marcos Francia
- Departamento de Química Biológica/Laboratorio de Regulación Génica en Células Madre, Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Buenos Aires, Argentina.,Instituto de Química Biológica (IQUIBICEN), CONICET - Universidad de Buenos Aires, Intendente Guiraldes 2160, Ciudad Universitaria, Pab. 2, 4to piso, QB-71, Buenos Aires, Argentina
| | - Lino Barañao
- Departamento de Química Biológica/Laboratorio de Regulación Génica en Células Madre, Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Buenos Aires, Argentina.,Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Santiago Miriuka
- Laboratorio de Investigación de Aplicación a Neurociencias (LIAN), CONICET - Fundación para la Lucha contra las Enfermedades Neurológicas de la Infancia (FLENI), Buenos Aires, Argentina.,Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Alejandra Guberman
- Departamento de Química Biológica/Laboratorio de Regulación Génica en Células Madre, Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Buenos Aires, Argentina. .,Instituto de Química Biológica (IQUIBICEN), CONICET - Universidad de Buenos Aires, Intendente Guiraldes 2160, Ciudad Universitaria, Pab. 2, 4to piso, QB-71, Buenos Aires, Argentina. .,Departamento de Fisiología y Biología Molecular y Celular, Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Buenos Aires, Argentina. .,Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina.
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6
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Cho SJ, Kim KT, Jeong HC, Park JC, Kwon OS, Song YH, Shin JG, Kang S, Kim W, Shin HD, Lee MO, Moon SH, Cha HJ. Selective Elimination of Culture-Adapted Human Embryonic Stem Cells with BH3 Mimetics. Stem Cell Reports 2018; 11:1244-1256. [PMID: 30293852 PMCID: PMC6235677 DOI: 10.1016/j.stemcr.2018.09.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Revised: 09/04/2018] [Accepted: 09/05/2018] [Indexed: 01/05/2023] Open
Abstract
The selective survival advantage of culture-adapted human embryonic stem cells (hESCs) is a serious safety concern for their clinical application. With a set of hESCs with various passage numbers, we observed that a subpopulation of hESCs at late passage numbers was highly resistant to various cell death stimuli, such as YM155, a survivin inhibitor. Transcriptome analysis from YM155-sensitive (YM155S) and YM155-resistant (YM155R) hESCs demonstrated that BCL2L1 was highly expressed in YM155R hESCs. By matching the gene signature of YM155R hESCs with the Cancer Therapeutics Response Portal dataset, BH3 mimetics were predicted to selectively ablate these cells. Indeed, short-course treatment with a sub-optimal dose of BH3 mimetics induced the spontaneous death of YM155R, but not YM155S hESCs by disrupting the mitochondrial membrane potential. YM155S hESCs remained pluripotent following BH3 mimetics treatment. Therefore, the use of BH3 mimetics is a promising strategy to specifically eliminate hESCs with a selective survival advantage. Culture-adapted hESCs against YM155/genotoxic agents mediated by high BCL-xL expression Selective cell death of culture-adapted hPSCs by BH3 mimetics Pluripotency maintenance of normal hESCs after exposure to BH3 mimetics
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Affiliation(s)
- Seung-Ju Cho
- Department of Life Sciences, Sogang University, Seoul 04107, Republic of Korea
| | - Keun-Tae Kim
- Department of Life Sciences, Sogang University, Seoul 04107, Republic of Korea
| | - Ho-Chang Jeong
- Department of Life Sciences, Sogang University, Seoul 04107, Republic of Korea
| | - Ju-Chan Park
- School of Pharmacy, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea
| | - Ok-Seon Kwon
- School of Pharmacy, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea
| | - Yun-Ho Song
- Department of Medicine, School of Medicine, Konkuk University, 120 Neungdong-ro, Gwangjin-gu, Seoul 05029, Republic of Korea
| | - Joong-Gon Shin
- Department of Life Sciences, Sogang University, Seoul 04107, Republic of Korea
| | - Seungmin Kang
- Ewha Research Center for Systems Biology, Division of Molecular & Life Sciences, Ewha Womans University, Seoul 03760, Republic of Korea
| | - Wankyu Kim
- Ewha Research Center for Systems Biology, Division of Molecular & Life Sciences, Ewha Womans University, Seoul 03760, Republic of Korea
| | - Hyoung Doo Shin
- Department of Life Sciences, Sogang University, Seoul 04107, Republic of Korea
| | - Mi-Ok Lee
- Immunotherapy Convergence Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon 34141, Republic of Korea
| | - Sung-Hwan Moon
- Department of Medicine, School of Medicine, Konkuk University, 120 Neungdong-ro, Gwangjin-gu, Seoul 05029, Republic of Korea.
| | - Hyuk-Jin Cha
- School of Pharmacy, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea.
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7
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Solari C, Petrone MV, Vazquez Echegaray C, Cosentino MS, Waisman A, Francia M, Barañao L, Miriuka S, Guberman A. Superoxide dismutase 1 expression is modulated by the core pluripotency transcription factors Oct4, Sox2 and Nanog in embryonic stem cells. Mech Dev 2018; 154:116-121. [PMID: 29933066 DOI: 10.1016/j.mod.2018.06.004] [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] [Received: 03/27/2018] [Revised: 06/13/2018] [Accepted: 06/18/2018] [Indexed: 02/02/2023]
Abstract
Redox homeostasis is vital for cellular functions and to prevent the detrimental consequences of oxidative stress. Pluripotent stem cells (PSCs) have an enhanced antioxidant system which supports the preservation of their genome. Besides, reactive oxygen species (ROS) are proposed to be involved in both self-renewal maintenance and in differentiation in embryonic stem cells (ESCs). Increasing evidence shows that cellular systems related to the oxidative stress defense decline along differentiation of PSCs. Although redox homeostasis has been extensively studied for many years, the knowledge about the transcriptional regulation of the genes involved in these systems is still limited. In this work, we studied Sod1 gene modulation by the PSCs fundamental transcription factors Oct4, Sox2 and Nanog. We found that this gene, which is expressed in mouse ESCs (mESCs), was repressed when they were induced to differentiate. Accordingly, these factors induced Sod1 promoter activity in a trans-activation assay. Finally, Sod1 mRNA levels were reduced when Oct4, Sox2 and Nanog were down-regulated by a shRNA approach in mESCs. Taken together, we found that PSCs' key transcription factors are involved in the modulation of Sod1 gene, suggesting a relationship between the pluripotency core and redox homeostasis in these cells.
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Affiliation(s)
- Claudia Solari
- Laboratorio de Regulación Génica en Células Madre, Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina; Instituto de Química Biológica (IQUIBICEN), Universidad de Buenos Aires - CONICET, Buenos Aires, Argentina.
| | - María Victoria Petrone
- Laboratorio de Regulación Génica en Células Madre, Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina; Instituto de Química Biológica (IQUIBICEN), Universidad de Buenos Aires - CONICET, Buenos Aires, Argentina.
| | - Camila Vazquez Echegaray
- Laboratorio de Regulación Génica en Células Madre, Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina; Instituto de Química Biológica (IQUIBICEN), Universidad de Buenos Aires - CONICET, Buenos Aires, Argentina.
| | - María Soledad Cosentino
- Laboratorio de Regulación Génica en Células Madre, Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina; Instituto de Química Biológica (IQUIBICEN), Universidad de Buenos Aires - CONICET, Buenos Aires, Argentina.
| | - Ariel Waisman
- Laboratorio de Regulación Génica en Células Madre, Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina; Instituto de Química Biológica (IQUIBICEN), Universidad de Buenos Aires - CONICET, Buenos Aires, Argentina
| | - Marcos Francia
- Laboratorio de Regulación Génica en Células Madre, Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina; Instituto de Química Biológica (IQUIBICEN), Universidad de Buenos Aires - CONICET, Buenos Aires, Argentina
| | - Lino Barañao
- Laboratorio de Regulación Génica en Células Madre, Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina.
| | - Santiago Miriuka
- Laboratorio de Investigación de Aplicación a Neurociencias (LIAN), Fundación para la Lucha contra las Enfermedades Neurológicas de la Infancia (FLENI) - CONICET, Buenos Aires, Argentina.
| | - Alejandra Guberman
- Laboratorio de Regulación Génica en Células Madre, Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina; Instituto de Química Biológica (IQUIBICEN), Universidad de Buenos Aires - CONICET, Buenos Aires, Argentina; Departamento de Fisiología y Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina.
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8
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Chen IC, Hernandez C, Xu X, Cooney A, Wang Y, McCarrey JR. Dynamic Variations in Genetic Integrity Accompany Changes in Cell Fate. Stem Cells Dev 2016; 25:1698-1708. [PMID: 27627671 DOI: 10.1089/scd.2016.0221] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Pluripotent stem cells hold the potential to form the basis of novel approaches to treatment of disease in vivo as well as to facilitate the generation of models for human disease, providing powerful avenues to discovery of novel diagnostic biomarkers and/or innovative drug regimens in vitro. However, this will require extensive maintenance, expansion, and manipulation of these cells in culture, which raises a concern regarding the extent to which genetic integrity will be preserved throughout these manipulations. We used a mutation reporter (lacI) transgene approach to conduct direct comparisons of mutation frequencies in cell populations that shared a common origin and genetic identity, but were induced to undergo transitions in cell fate between pluripotent and differentiated states, or vice versa. We confirm that pluripotent cells normally maintain enhanced genetic integrity relative to that in differentiated cells, and we extend this finding to show that dynamic transformations in the relative stringency at which genetic integrity is maintained are associated with transitions between pluripotent and differentiated cellular states. These results provide insight into basic biological distinctions between pluripotent and differentiated cell types that impact genetic integrity in a manner that is directly relevant to the potential clinical use of these cell types.
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Affiliation(s)
- I-Chung Chen
- 1 Department of Biology, University of Texas at San Antonio , San Antonio, Texas
| | - Christine Hernandez
- 1 Department of Biology, University of Texas at San Antonio , San Antonio, Texas
| | - Xueping Xu
- 2 Institute for Applied Cancer Science, The University of Texas MD Anderson Cancer Center , Houston, Texas
| | - Austin Cooney
- 2 Institute for Applied Cancer Science, The University of Texas MD Anderson Cancer Center , Houston, Texas.,3 Department of Pediatrics, Dell Pediatric Research Institute, University of Texas at Austin Dell , Medical School, Austin, Texas
| | - Yufeng Wang
- 1 Department of Biology, University of Texas at San Antonio , San Antonio, Texas
| | - John R McCarrey
- 1 Department of Biology, University of Texas at San Antonio , San Antonio, Texas
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9
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Solari C, Vázquez Echegaray C, Cosentino MS, Petrone MV, Waisman A, Luzzani C, Francia M, Villodre E, Lenz G, Miriuka S, Barañao L, Guberman A. Manganese Superoxide Dismutase Gene Expression Is Induced by Nanog and Oct4, Essential Pluripotent Stem Cells' Transcription Factors. PLoS One 2015; 10:e0144336. [PMID: 26642061 PMCID: PMC4671669 DOI: 10.1371/journal.pone.0144336] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Accepted: 11/17/2015] [Indexed: 01/29/2023] Open
Abstract
Pluripotent stem cells possess complex systems that protect them from oxidative stress and ensure genomic stability, vital for their role in development. Even though it has been reported that antioxidant activity diminishes along stem cell differentiation, little is known about the transcriptional regulation of the involved genes. The reported modulation of some of these genes led us to hypothesize that some of them could be regulated by the transcription factors critical for self-renewal and pluripotency in embryonic stem cells (ESCs) and in induced pluripotent stem cells (iPSCs). In this work, we studied the expression profile of multiple genes involved in antioxidant defense systems in both ESCs and iPSCs. We found that Manganese superoxide dismutase gene (Mn-Sod/Sod2) was repressed during diverse differentiation protocols showing an expression pattern similar to Nanog gene. Moreover, Sod2 promoter activity was induced by Oct4 and Nanog when we performed a transactivation assay using two different reporter constructions. Finally, we studied Sod2 gene regulation by modulating the expression of Oct4 and Nanog in ESCs by shRNAs and found that downregulation of any of them reduced Sod2 expression. Our results indicate that pluripotency transcription factors positively modulate Sod2 gene transcription.
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Affiliation(s)
- Claudia Solari
- Laboratorio de Regulación Génica en Células Madre, Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
- Instituto de Química Biológica (IQUIBICEN), UBA-CONICET, Buenos Aires, Argentina
| | - Camila Vázquez Echegaray
- Laboratorio de Regulación Génica en Células Madre, Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
- Instituto de Química Biológica (IQUIBICEN), UBA-CONICET, Buenos Aires, Argentina
| | - María Soledad Cosentino
- Laboratorio de Regulación Génica en Células Madre, Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
- Instituto de Química Biológica (IQUIBICEN), UBA-CONICET, Buenos Aires, Argentina
| | - María Victoria Petrone
- Laboratorio de Regulación Génica en Células Madre, Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
- Instituto de Química Biológica (IQUIBICEN), UBA-CONICET, Buenos Aires, Argentina
| | - Ariel Waisman
- Laboratorio de Regulación Génica en Células Madre, Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
- Instituto de Química Biológica (IQUIBICEN), UBA-CONICET, Buenos Aires, Argentina
| | - Carlos Luzzani
- Laboratorio de Regulación Génica en Células Madre, Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
- Instituto de Química Biológica (IQUIBICEN), UBA-CONICET, Buenos Aires, Argentina
| | - Marcos Francia
- Laboratorio de Regulación Génica en Células Madre, Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
- Instituto de Química Biológica (IQUIBICEN), UBA-CONICET, Buenos Aires, Argentina
| | - Emilly Villodre
- Laboratório de Sinalização Celular, Departamento de Biofísica, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brasil
| | - Guido Lenz
- Laboratório de Sinalização Celular, Departamento de Biofísica, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brasil
| | - Santiago Miriuka
- Laboratorio de Investigación Aplicada a las Neurociencias (LIAN), Fundación para la Lucha contra las Enfermedades Neurológicas de la Infancia (FLENI), Buenos Aires, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Lino Barañao
- Laboratorio de Regulación Génica en Células Madre, Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
- Instituto de Química Biológica (IQUIBICEN), UBA-CONICET, Buenos Aires, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Alejandra Guberman
- Laboratorio de Regulación Génica en Células Madre, Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
- Instituto de Química Biológica (IQUIBICEN), UBA-CONICET, Buenos Aires, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
- Departamento de Fisiología y Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
- * E-mail:
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10
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Mathematical modeling of growth and death dynamics of mouse embryonic stem cells irradiated with γ-rays. J Theor Biol 2014; 363:374-80. [PMID: 25195003 DOI: 10.1016/j.jtbi.2014.08.042] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2014] [Revised: 08/12/2014] [Accepted: 08/24/2014] [Indexed: 11/22/2022]
Abstract
Following ionizing radiation, mouse embryonic stem cells (mESCs) undergo both apoptosis and block at G2/M phase of the cell cycle. The dynamics of cell growth and the transition through the apoptotic phases cannot be directly inferred from experimental data, limiting the understanding of the biological response to the treatment. Here, we propose a semi-mechanistic mathematical model, defined by five compartments, able to describe the time curves of untreated and γ-rays irradiated mESCs and to extract the information therein embedded. To this end, mESCs were irradiated with 2 or 5 Gy γ-rays, collected over a period of 48 h and, at each time point, analyzed for apoptosis by using the Annexin V assay. When compared to unirradiated mESCs, the model estimates an additional 0.2 probability to undergo apoptosis for the 5 Gy-treated cells, and only a 0.07 (not statistically significantly different from zero) when a 2 Gy-irradiation dose is administered. Moreover, the model allows us to estimate the duration of the overall apoptotic process and also the time length of its early, intermediate, and late apoptotic phase.
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11
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Inhibition of pluripotent stem cell-derived teratoma formation by small molecules. Proc Natl Acad Sci U S A 2013; 110:E3281-90. [PMID: 23918355 DOI: 10.1073/pnas.1303669110] [Citation(s) in RCA: 177] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The future of safe cell-based therapy rests on overcoming teratoma/tumor formation, in particular when using human pluripotent stem cells (hPSCs), such as human embryonic stem cells (hESCs) and human induced pluripotent stem cells (hiPSCs). Because the presence of a few remaining undifferentiated hPSCs can cause undesirable teratomas after transplantation, complete removal of these cells with no/minimal damage to differentiated cells is a prerequisite for clinical application of hPSC-based therapy. Having identified a unique hESC signature of pro- and antiapoptotic gene expression profile, we hypothesized that targeting hPSC-specific antiapoptotic factor(s) (i.e., survivin or Bcl10) represents an efficient strategy to selectively eliminate pluripotent cells with teratoma potential. Here we report the successful identification of small molecules that can effectively inhibit these antiapoptotic factors, leading to selective and efficient removal of pluripotent stem cells through apoptotic cell death. In particular, a single treatment of hESC-derived mixed population with chemical inhibitors of survivin (e.g., quercetin or YM155) induced selective and complete cell death of undifferentiated hPSCs. In contrast, differentiated cell types (e.g., dopamine neurons and smooth-muscle cells) derived from hPSCs survived well and maintained their functionality. We found that quercetin-induced selective cell death is caused by mitochondrial accumulation of p53 and is sufficient to prevent teratoma formation after transplantation of hESC- or hiPSC-derived cells. Taken together, these results provide the "proof of concept" that small-molecule targeting of hPSC-specific antiapoptotic pathway(s) is a viable strategy to prevent tumor formation by selectively eliminating remaining undifferentiated pluripotent cells for safe hPSC-based therapy.
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12
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Rebuzzini P, Fassina L, Mulas F, Bellazzi R, Redi CA, Di Liberto R, Magenes G, Adjaye J, Zuccotti M, Garagna S. Mouse embryonic stem cells irradiated with γ-rays differentiate into cardiomyocytes but with altered contractile properties. Mutat Res 2013; 756:37-45. [PMID: 23792212 DOI: 10.1016/j.mrgentox.2013.06.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2013] [Accepted: 06/11/2013] [Indexed: 12/15/2022]
Abstract
Embryonic stem cells (ESCs) for their derivation from the inner cell mass of a blastocyst represent a valuable in vitro model to investigate the effects of ionizing radiation on early embryonic cellular response. Following irradiation, both human and mouse ESCs (mESCs) maintain their pluripotent status and the capacity to differentiate into embryoid bodies and to form teratomas. Although informative of the maintenance of a pluripotent status, these studies never investigated the capability of irradiated ESCs to form specific differentiated phenotypes. Here, for the first time, 5Gy-irradiated mESCs were differentiated into cardiomyocytes, thus allowing the analysis of the long-term effects of ionizing radiations on the differentiation potential of a pluripotent stem cell population. On treated mESCs, 96h after irradiation, a genome-wide expression analysis was first performed in order to determine whether the treatment influenced gene expression of the surviving mESCs. Microarrays analysis showed that only 186 genes were differentially expressed in treated mESCs compared to control cells; a quarter of these genes were involved in cellular differentiation, with three main gene networks emerging, including cardiogenesis. Based on these results, we differentiated irradiated mESCs into cardiomyocytes. On day 5, 8 and 12 of differentiation, treated cells showed a significant alteration (qRT-PCR) of the expression of marker genes (Gata-4, Nkx-2.5, Tnnc1 and Alpk3) when compared to control cells. At day 15 of differentiation, although the organization of sarcomeric α-actinin and troponin T proteins appeared similar in cardiomyocytes differentiated from either mock or treated cells, the video evaluation of the kinematics and dynamics of the beating cardiac syncytium evidenced altered contractile properties of cardiomyocytes derived from irradiated mESCs. This alteration correlated with significant reduction of Connexin 43 foci. Our results indicate that mESCs populations that survive an ionizing irradiation treatment are capable to differentiate into cardiomyocytes, but they have altered contractile properties.
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Affiliation(s)
- Paola Rebuzzini
- Laboratorio di Biologia dello Sviluppo, Dipartimento di Biologia e Biotecnologie 'Lazzaro Spallanzani', Università degli Studi di Pavia, Via Ferrata 9, 27100 Pavia, Italy
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13
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Sverdlov ED, Mineev K. Mutation rate in stem cells: an underestimated barrier on the way to therapy. Trends Mol Med 2013; 19:273-80. [PMID: 23481596 DOI: 10.1016/j.molmed.2013.01.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2012] [Revised: 01/15/2013] [Accepted: 01/24/2013] [Indexed: 12/23/2022]
Abstract
Stem cells (SCs) are thought to have great therapeutic potential, but due to continuously and stochastically arising new mutations that unpredictably change the composition of a cell population, the large-scale manufacturing of SCs with uniform properties and predictable behavior is a challenge. Quantitative evaluation of the characteristic mutation rate of a given stem cell line could be an important criterion in making the decision to use the line in medical practice. Such an evaluation could provide a new quality standard for newly derived human embryonic stem cell (hESC) lines prior to depositing them in stem cell banks. Here, we substantiate this view with simple calculations showing the effect of the mutation rate on changes in the cell population composition due to amplification. Selection of SCs with low mutation rate could reduce the risk of negative side effects during treatment.
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Affiliation(s)
- Eugene D Sverdlov
- Institute of Molecular Genetics, Russian Academy of Sciences, 2 Kurchatov Sq., Moscow, 123182, Russia.
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14
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Murphey P, McLean DJ, McMahan CA, Walter CA, McCarrey JR. Enhanced genetic integrity in mouse germ cells. Biol Reprod 2013; 88:6. [PMID: 23153565 DOI: 10.1095/biolreprod.112.103481] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Genetically based diseases constitute a major human health burden, and de novo germline mutations represent a source of heritable genetic alterations that can cause such disorders in offspring. The availability of transgenic rodent systems with recoverable, mutation reporter genes has been used to assess the occurrence of spontaneous point mutations in germline cells. Previous studies using the lacI mutation reporter transgenic mouse system showed that the frequency of spontaneous mutations is significantly lower in advanced male germ cells than in somatic cell types from the same individuals. Here we used this same mutation reporter transgene system to show that female germ cells also display a mutation frequency that is lower than that in corresponding somatic cells and similar to that seen in male germ cells, indicating this is a common feature of germ cells in both sexes. In addition, we showed that statistically significant differences in mutation frequencies are evident between germ cells and somatic cells in both sexes as early as mid-fetal stages in the mouse. Finally, a comparison of the mutation frequency in a general population of early type A spermatogonia with that in a population enriched for Thy-1-positive spermatogonia suggests there is heterogeneity among the early spermatogonial population such that a subset of these cells are predestined to form true spermatogonial stem cells. Taken together, these results support the disposable soma theory, which posits that genetic integrity is normally maintained more stringently in the germ line than in the soma and suggests that this is achieved by minimizing the initial occurrence of mutations in early germline cells and their subsequent gametogenic progeny relative to that in somatic cells.
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Affiliation(s)
- Patricia Murphey
- Department of Biology, University of Texas at San Antonio, San Antonio, TX 78249, USA
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15
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Khromov T, Dressel R, Siamishi I, Nolte J, Opitz L, Engel W, Pantakani DVK. Apoptosis-related gene expression profiles of mouse ESCs and maGSCs: role of Fgf4 and Mnda in pluripotent cell responses to genotoxicity. PLoS One 2012; 7:e48869. [PMID: 23145002 PMCID: PMC3492253 DOI: 10.1371/journal.pone.0048869] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2012] [Accepted: 10/02/2012] [Indexed: 01/27/2023] Open
Abstract
Stem cells in the developing embryo proliferate and differentiate while maintaining genomic integrity, failure of which may lead to accumulation of mutations and subsequent damage to the embryo. Embryonic stem cells (ESCs), the in vitro counterpart of embryo stem cells are highly sensitive to genotoxic stress. Defective ESCs undergo either efficient DNA damage repair or apoptosis, thus maintaining genomic integrity. However, the genotoxicity- and apoptosis-related processes in germ-line derived pluripotent cells, multipotent adult germ-line stem cells (maGSCs), are currently unknown. Here, we analyzed the expression of apoptosis-related genes using OligoGEArray in undifferentiated maGSCs and ESCs and identified a similar set of genes expressed in both cell types. We detected the expression of intrinsic, but not extrinsic, apoptotic pathway genes in both cell types. Further, we found that apoptosis-related gene expression patterns of differentiated ESCs and maGSCs are identical to each other. Comparative analysis revealed that several pro- and anti-apoptotic genes are expressed specifically in pluripotent cells, but markedly downregulated in the differentiated counterparts of these cells. Activation of the intrinsic apoptotic pathway cause approximately ∼35% of both ESCs and maGSCs to adopt an early-apoptotic phenotype. Moreover, we performed transcriptome studies using early-apoptotic cells to identify novel pluripotency- and apoptosis-related genes. From these transcriptome studies, we selected Fgf4 (Fibroblast growth factor 4) and Mnda (Myeloid cell nuclear differentiating antigen), which are highly downregulated in early-apoptotic cells, as novel candidates and analyzed their roles in apoptosis and genotoxicity responses in ESCs. Collectively, our results show the existence of common molecular mechanisms for maintaining the pristine stem cell pool of both ESCs and maGSCs.
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Affiliation(s)
- Tatjana Khromov
- Institute of Human Genetics, University of Goettingen, Goettingen, Germany
| | - Ralf Dressel
- Department of Cellular and Molecular Immunology, University of Goettingen, Goettingen, Germany
| | - Iliana Siamishi
- Institute of Human Genetics, University of Goettingen, Goettingen, Germany
| | - Jessica Nolte
- Institute of Human Genetics, University of Goettingen, Goettingen, Germany
| | - Lennart Opitz
- DNA Microarray Facility, University of Goettingen, Goettingen, Germany
| | - Wolfgang Engel
- Institute of Human Genetics, University of Goettingen, Goettingen, Germany
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16
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Rebuzzini P, Pignalosa D, Mazzini G, Di Liberto R, Coppola A, Terranova N, Magni P, Redi CA, Zuccotti M, Garagna S. Mouse embryonic stem cells that survive γ-rays exposure maintain pluripotent differentiation potential and genome stability. J Cell Physiol 2012; 227:1242-9. [PMID: 21732352 DOI: 10.1002/jcp.22908] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
This study aimed to investigate the cell cycle, apoptosis, cytogenetics and differentiation capacity of mouse embryonic stem cells (mESCs) that survived a single dose of 2 or 5 Gy γ-rays during a period of up to 96 h of culture. After 2 Gy irradiation and 24 h culture, compared to control, a significant majority of cells was blocked at the G2/M phase and a massive apoptosis was recorded. Between 48 and 72 h post-irradiation, the parameters used to describe the cell cycle and apoptosis returned similar to those of control samples. When mESCs were irradiated with 5 Gy, a small fraction of cells, even after 96 h of culture, still presented clear evidences of a G2/M block and apoptosis. The cytogenetic analysis performed at 96 h showed that the structural stability of the aberrations did not change significantly when comparing control and 2 or 5 Gy-treated populations. However, the chromosomal damage observed in the progeny of the survived cells after 5 Gy exposure is significantly higher than that observed in control samples, although it is mostly of the stable and transmissible type. Ninety-six hours after irradiation, the survived mESCs maintained their undifferentiated status and capability to differentiate into the three germ layers. Overall, these results indicate a commitment of mESCs to maintain pluripotency and genome stability.
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Affiliation(s)
- Paola Rebuzzini
- Laboratorio di Biologia dello Sviluppo, Dipartimento di Biologia Animale, Università degli Studi di Pavia, Pavia, Italy
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17
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Abstract
The embryonic ventricular and subventricular zones (VZ/SVZ) contain the neuronal stem and progenitor cells and undergo rapid proliferation. The intermediate zone (IZ) contains nonreplicating, differentiated cells. The VZ/SVZ is hypersensitive to radiation-induced apoptosis. Ablation of DNA non-homologous end-joining (NHEJ) proteins, XRCC4 or DNA ligase IV (LigIV), confers ataxia telangiectasia mutated (ATM)-dependent apoptosis predominantly in the IZ. We examine the mechanistic basis underlying these distinct sensitivities using a viable LigIV (Lig4(Y288C)) mouse, which permits an examination of the DNA damage responses in the embryonic and adult brain. Via combined analysis of DNA breakage, apoptosis, and cell-cycle checkpoint control in tissues, we show that apoptosis in the VZ/SVZ and IZ is activated by low numbers of DNA double-strand breaks (DSBs). Unexpectedly, high sensitivity in the VZ/SVZ arises from sensitive activation of ATM-dependent apoptosis plus an ATM-independent process. In contrast, the IZ appears to be hypersensitive to persistent DSBs. NHEJ functions efficiently in both compartments. The VZ/SVZ and IZ regions incur high endogenous DNA breakage, which correlates with VZ proliferation. We demonstrate a functional G(2)/M checkpoint in VZ/SVZ cells and show that it is not activated by low numbers of DSBs, allowing damaged VZ/SVZ cells to transit into the IZ. We propose a novel model in which microcephaly in LIG4 syndrome arises from sensitive apoptotic induction from persisting DSBs in the IZ, which arise from high endogenous breakage in the VZ/SVZ and transit of damaged cells to the IZ. The VZ/SVZ, in contrast, is highly sensitive to acute radiation-induced DSB formation.
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18
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Guo YL, Chakraborty S, Rajan SS, Wang R, Huang F. Effects of oxidative stress on mouse embryonic stem cell proliferation, apoptosis, senescence, and self-renewal. Stem Cells Dev 2011; 19:1321-31. [PMID: 20092403 DOI: 10.1089/scd.2009.0313] [Citation(s) in RCA: 103] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Oxidative stress, associated with either normal metabolism or disease conditions, affects many cellular activities. Most of our knowledge in this field is derived from fully differentiated cells. Embryonic stem cells (ESCs) have attracted enormous attention for their potential applications in cell therapy, but little is known about how the unique properties of ESCs are affected by oxidative stress. We have investigated the effects of oxidative stress induced by H(2)O(2) on several cellular activities of mouse ESCs. Like differentiated cells, ESCs are sensitive to H(2)O(2)-induced apoptosis when continuously exposed to H(2)O(2) at the concentrations above 150 microM. However, unlike differentiated cells, ESCs are resistant to oxidative stress induced senescence. This is demonstrated by the results that when subjected to a short-term sublethal concentration and duration of H(2)O(2) treatment, fibroblasts enter the senescent state with enlarged flattened cell morphology concurrent with increased expression of senescence marker p21. On the contrary, ESCs neither show any sign of senescence nor express p21. Instead, ESCs enter a transient cell cycle arrest state, but they have remarkable recovery capacity to resume the normal cell proliferation rate without losing the ability of self-renewal and pluripotency. Our results further revealed that H(2)O(2) inhibits cell adhesion and the expression of cyclin D1, which are early events proceeding apoptosis and cell cycle arrest. In conclusion, our data suggest that ESCs are sensitive to H(2)O(2) toxicity, but may have unique mechanisms that prevent H(2)O(2)-induced senescence and protect self-renewal capacity.
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Affiliation(s)
- Yan-Lin Guo
- Department of Biological Sciences, The University of Southern Mississippi, Hattiesburg, Mississippi 39406, USA.
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19
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Abstract
Why do we age? Since ageing is a near-universal feature of complex organisms, a convincing theory must provide a robust evolutionary explanation for its ubiquity. This theory should be compatible with the physiological evidence that ageing is largely due to deterioration, which is, in principle, reversible through repair. Moreover, this theory should also explain why natural selection has favoured organisms that first improve with age (mortality rates decrease) and then deteriorate with age (mortality rates rise). We present a candidate for such a theory of life history, applied initially to a species with determinate growth. The model features both the quantity and the quality of somatic capital, where it is optimal to initially build up quantity, but to allow quality to deteriorate. The main theoretical result of the paper is that a life history where mortality decreases early in life and then increases late in life is evolutionarily optimal. In order to apply the model to humans, in particular, we include a budget constraint to allow intergenerational transfers. The resultant theory then accounts for all our basic demographic characteristics, including menopause with extended survival after reproduction has ceased.
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Affiliation(s)
- Hillard S Kaplan
- Department of Anthropology, University of New Mexico, Albuquerque, NM 87131, USA.
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20
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Banáth JP, Bañuelos CA, Klokov D, MacPhail SM, Lansdorp PM, Olive PL. Explanation for excessive DNA single-strand breaks and endogenous repair foci in pluripotent mouse embryonic stem cells. Exp Cell Res 2008; 315:1505-20. [PMID: 19154734 DOI: 10.1016/j.yexcr.2008.12.007] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2008] [Revised: 12/04/2008] [Accepted: 12/05/2008] [Indexed: 12/16/2022]
Abstract
Pluripotent mouse embryonic stem cells (mES cells) exhibit approximately 100 large gammaH2AX repair foci in the absence of measurable numbers of DNA double-strand breaks. Many of these cells also show excessive numbers of DNA single-strand breaks (>10,000 per cell) when analyzed using the alkaline comet assay. To understand the reasons for these unexpected observations, various methods for detecting DNA strand breaks were applied to wild-type mES cells and to mES cells lacking H2AX, ATM, or DNA-PKcs. H2AX phosphorylation and expression of other repair complexes were measured using flow and image analysis of antibody-stained cells. Results indicate that high numbers of endogenous gammaH2AX foci and single-strand breaks in pluripotent mES cells do not require ATM or DNA-PK kinase activity and appear to be associated with global chromatin decondensation rather than pre-existing DNA damage. This will limit applications of gammaH2AX foci analysis in mES cells to relatively high levels of initial or residual DNA damage. Excessive numbers of single-strand breaks in the alkaline comet assay can be explained by the vulnerability of replicating chromatin in mES cells to osmotic shock. This suggests that caution is needed in interpreting results with the alkaline comet assay when applied to certain cell types or after treatment with agents that make chromatin vulnerable to osmotic changes. Differentiation of mES cells caused a reduction in histone acetylation, gammaH2AX foci intensity, and DNA single-strand breakage, providing a link between chromatin structural organization, excessive gammaH2AX foci, and sensitivity of replicating mES cell chromatin to osmotic shock.
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Affiliation(s)
- J P Banáth
- British Columbia Cancer Research Centre, Vancouver, B.C., Canada, V5Z 1L3
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21
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Zhao H, Tanaka T, Mitlitski V, Heeter J, Balazs EA, Darzynkiewicz Z. Protective effect of hyaluronate on oxidative DNA damage in WI-38 and A549 cells. Int J Oncol 2008; 32:1159-67. [PMID: 18497977 DOI: 10.3892/ijo_32_6_1159] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Progressive DNA damage in live cells by oxidants is the key factor contributing to cell aging and preconditioning to neoplastic transformation. The strategies to slow aging or prevent cancer rely on protection of DNA from the damage. Since cells reside within intercellular matrix it is of interest to know whether matrix constituents possess properties of modulating oxidative DNA damage. We explored, therefore, the effect of hyaluronate (HA), the ubiquitous component of the matrix, on extent of DNA damage induced by exogenous and endogenously generated oxidants. WI-38 and A549 cells were exposed to 200 microM H2O2 in the absence or presence of HA and induction of histone H2AX phosphorylation and activation of ATM, the reporters of DNA damage, was assessed by multiparameter cytometry. Also explored was effect of HA on constitutive H2AX phosphorylation that reflects DNA damage caused by endogenous oxidants generated during aerobic metabolism. HA of average MW 5.4 million (high MW) and 2 million (medium MW) at 0.1% (w/v) in culture medium totally prevented the H2O2-induced H2AX phosphorylation in both cell types whereas effect of 60,000 average MW (low MW) HA was somewhat less pronounced. Constitutive H2AX phosphorylation in WI-38 cells growing in the presence of 0.1% HA of low MW and medium MW was reduced by about 35 and 30%, respectively; no reduction was observed in A549 cells. The data indicate that HA protected DNA from damage caused by the exogenous oxidant H2O2. In WI-38 fibroblasts, the cells that express the HA-receptor CD44, HA also protected DNA from damage caused by endogenous oxidants. We postulate that expression of CD44 in some cell types such as stem cells may provide the means to internalize HA by endocytosis and one of the functions of the internalized HA may be protection of DNA from oxidants. The mechanism of protective effect of HA may either: i) involve entrapment of iron ions thereby inhibiting the Fenton's reaction that produces secondary oxidative species, and/or: ii) directly scavenging of primary and secondary ROIs, as an antioxidant, resulting in HA degradation. Since no significant degradation of HA upon its exposure in tissue culture medium to H2O2 was detected the scavenging may occur intracellularly.
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Affiliation(s)
- Hong Zhao
- Brander Cancer Research Institute and Department of Pathology, New York Medical College, Valhalla, NY 10595, USA
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Abstract
PURPOSE OF REVIEW Many genes affect pathways that predispose to and protect against obesity. We ask how many different variants affect human obesity and how common are they? RECENT FINDINGS The current generation of genome-wide association scans is moderately powered to detect and replicate associations between single nucleotide polymorphisms, or common copy number variations and common diseases. They are not designed either to find rare germline variants or those somatic changes, unique to an individual, that arise with high frequency in adult stem cells. They do not directly assay the epigenetic reprogramming of outcomes related to maternal or environmental exposures. SUMMARY There are more gene variants, more gene-gene and gene-environmental interactions leading to obesity than current genome-wide association scan studies can verify. Those genetic associations that can be validated provide valuable insight into the pathways contributing to human obesity.
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Affiliation(s)
- Alan Herbert
- Department of Genetics and Genomics, Boston University School of Medicine, Boston, Massachusetts 02118, USA.
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23
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Saretzki G, Walter T, Atkinson S, Passos JF, Bareth B, Keith WN, Stewart R, Hoare S, Stojkovic M, Armstrong L, von Zglinicki T, Lako M. Downregulation of multiple stress defense mechanisms during differentiation of human embryonic stem cells. Stem Cells 2007; 26:455-64. [PMID: 18055443 DOI: 10.1634/stemcells.2007-0628] [Citation(s) in RCA: 190] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Evolutionary theory predicts that cellular maintenance, stress defense, and DNA repair mechanisms should be most active in germ line cells, including embryonic stem cells that can differentiate into germ line cells, whereas it would be energetically unfavorable to keep these up in mortal somatic cells. We tested this hypothesis by examining telomere maintenance, oxidative stress generation, and genes involved in antioxidant defense and DNA repair during spontaneous differentiation of two human embryonic stem cell lines. Telomerase activity was quickly downregulated during differentiation, probably due to deacetylation of histones H3 and H4 at the hTERT promoter and deacetylation of histone H3 at hTR promoter. Telomere length decreased accordingly. Mitochondrial superoxide production and cellular levels of reactive oxygen species increased as result of increased mitochondrial biogenesis. The expression of major antioxidant genes was downregulated despite this increased oxidative stress. DNA damage levels increased during differentiation, whereas expression of genes involved in different types of DNA repair decreased. These results confirm earlier data obtained during mouse embryonic stem cell differentiation and are in accordance with evolutionary predictions.
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Affiliation(s)
- Gabriele Saretzki
- Crucible Lab, Institute of Human Genetics, Central Parkway, Newcastle upon Tyne NE1 3BZ, United Kingdom.
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