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Ravi K, Bentounsi Z, Tariq A, Brazeal A, Daudu D, Back F, Elhadi M, Badwi N, Shah SSNH, Bandyopadhyay S, Khalil H, Kimura H, Sekyi-Djan MN, Abdelrahman A, Shaheen A, Mbonda Noula AG, Wong AT, Ndajiwo A, Souadka A, Maina AN, Nyalundja AD, Sabry A, Hind B, Nteranya DS, Ngugi DW, de Wet E, Tolis EA, Wafqui FZ, Essangri H, Moujtahid H, Moola H, Narain K, Ravi K, Wassim K, Odiero LA, Nyaboke LS, Metwalli M, Naisiae M, Pueschel MG, Turabi N, El Aroussi N, Makram OM, Shawky OA, Outani O, Carides P, Patil P, Halley-Stott RP, Kurbegovic S, Marchant S, Moujtahid S, El Hadrati S, Agarwal T, Kidavasi VA, Agarwal V, Steyn W, Matumo W, Fahmy YA, Omar Z, Amod Z, Eloff M, Hussein NA, Sharma D. Systematic analysis of authorship demographics in global surgery. BMJ Glob Health 2021; 6:bmjgh-2021-006672. [PMID: 34666988 PMCID: PMC8527109 DOI: 10.1136/bmjgh-2021-006672] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2021] [Accepted: 09/09/2021] [Indexed: 02/06/2023] Open
Abstract
Background Global surgery has recently gained prominence as an academic discipline within global health. Authorship inequity has been a consistent feature of global health publications, with over-representation of authors from high-income countries (HICs), and disenfranchisement of researchers from low-income and middle-income countries (LMICs). In this study, we investigated authorship demographics within recently published global surgery literature. Methods We performed a systematic analysis of author characteristics, including gender, seniority and institutional affiliation, for global surgery studies published between 2016 and 2020 and indexed in the PubMed database. We compared the distribution of author gender and seniority across studies related to different topics; between authors affiliated with HICs and LMICs; and across studies with different authorship networks. Results 1240 articles were included for analysis. Most authors were male (60%), affiliated only with HICs (51%) and of high seniority (55% were fully qualified specialist or generalist clinicians, Principal Investigators, or in senior leadership or management roles). The proportion of male authors increased with increasing seniority for last and middle authors. Studies related to Obstetrics and Gynaecology had similar numbers of male and female authors, whereas there were more male authors in studies related to surgery (69% male) and Anaesthesia and Critical care (65% male). Compared with HIC authors, LMIC authors had a lower proportion of female authors at every seniority grade. This gender gap among LMIC middle authors was reduced in studies where all authors were affiliated only with LMICs. Conclusion Authorship disparities are evident within global surgery academia. Remedial actions to address the lack of authorship opportunities for LMIC authors and female authors are required.
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Affiliation(s)
- Krithi Ravi
- University Hospital Southampton NHS Foundation Trust, Southampton, UK
| | - Zineb Bentounsi
- University Hospital Southampton NHS Foundation Trust, Southampton, UK
| | - Aiman Tariq
- National Institute of Cardiovascular Diseases, Karachi, Pakistan
| | | | - Davina Daudu
- The University of Western Australia Faculty of Health and Medical Sciences, Perth, Western Australia, Australia
| | - Francesca Back
- University of Oxford Medical Sciences Division, Oxford, UK
| | | | - Nermin Badwi
- Zagazig University Faculty of Human Medicine, Zagazig, Egypt.,InciSioN Egypt, Zagazig, Egypt
| | | | | | - Halimah Khalil
- Birmingham Medical School, University of Birmingham College of Medical and Dental Sciences, Birmingham, UK
| | | | | | | | - Ahmed Shaheen
- Alexandria University Faculty of Medicine, Alexandria, Egypt
| | | | - Ai-Ting Wong
- Red Cross War Memorial Children's Hospital, Rondebosch, South Africa
| | | | - Amine Souadka
- National Institute of Oncology, Mohammed V University of Rabat, Rabat, Morocco
| | | | | | | | - Bourja Hind
- Ibn Rochd University Hospital Center, Casablanca, Morocco
| | - Daniel Safari Nteranya
- Department of Surgery, Official University of Bukavu, Bukavu, Congo.,Association of Future African Neurosurgeons, Yaoundé, Cameroon
| | | | - Elsa de Wet
- University of the Free State, Bloemfontein, South Africa
| | | | - F Z Wafqui
- Faculty of Medicine and Pharmacy, Casablanca, Morocco
| | - Hajar Essangri
- National Institute of Oncology, Mohammed V University of Rabat, Rabat, Morocco
| | - Hajar Moujtahid
- Faculty of Medicine and Pharmacy, Mohammed V University of Rabat, Rabat, Morocco
| | - Husna Moola
- University of Cape Town, Rondebosch, South Africa
| | - Kapil Narain
- University of KwaZulu-Natal Nelson R Mandela School of Medicine, Durban, South Africa
| | - Krupa Ravi
- University of Oxford Medical Sciences Division, Oxford, UK
| | - Kyrillos Wassim
- Cairo University Kasr Alainy Faculty of Medicine, Cairo, Egypt
| | | | | | | | - Maryanne Naisiae
- University of Nairobi College of Health Sciences, Nairobi, Kenya
| | | | - Nafisa Turabi
- Netaji Subhash Chandra Bose Medical College and Hospital, Jabalpur, India
| | - Nouhaila El Aroussi
- Faculty of Medicine and Pharmacy, Mohammed V University of Rabat, Rabat, Morocco
| | - Omar Mohamed Makram
- Department of Cardiology, Faculty of Medicine, October 6 University, 6th of October City, Egypt.,London School of Hygiene and Tropical Medicine Faculty of Public Health and Policy, London, UK
| | - Omar A Shawky
- Cairo University Kasr Alainy Faculty of Medicine, Cairo, Egypt
| | - Oumaima Outani
- Faculty of Medicine and Pharmacy, Mohammed V University of Rabat, Rabat, Morocco
| | - Peter Carides
- University of the Witwatersrand, Johannesburg-Braamfontein, South Africa
| | | | | | - Sabina Kurbegovic
- Medical Faculty, University of Sarajevo, Sarajevo, Bosnia and Herzegovina
| | | | - Sara Moujtahid
- Ibn Sina University Hospital Center, Rabat, Morocco.,Mohammed V University, Rabat, Morocco
| | - Soukaina El Hadrati
- Faculty of Medicine and Pharmacy, Mohammed V University of Rabat, Rabat, Morocco
| | | | | | | | - Wilme Steyn
- Chris Hani Baragwanath Hospital, Bertsham, South Africa
| | | | | | - Zaayid Omar
- Rondebosch Medical Centre, Cape Town, South Africa
| | - Zachary Amod
- University of Cape Town, Rondebosch, South Africa
| | - Madelein Eloff
- University of KwaZulu-Natal Nelson R Mandela School of Medicine, Durban, South Africa
| | | | - Dhananjaya Sharma
- Department of Surgery, Netaji Subhash Chandra Bose Medical College and Hospital, Jabalpur, India
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2
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Halley-Stott RP, Adeola HA, Khumalo NP. Destruction of the stem cell Niche, Pathogenesis and Promising Treatment Targets for Primary Scarring Alopecias. Stem Cell Rev Rep 2020; 16:1105-1120. [PMID: 32789558 DOI: 10.1007/s12015-020-09985-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The Primary Scarring Alopecias are characterised by the irreversible destruction and fibrosis of hair follicles, leading to permanent and often disfiguring loss of hair. The pathophysiology of these diseases is not well understood. However, follicular-fibrosis and loss of the stem-cell niche appears to be a common theme. This review explores the pathogenesis of primary scarring alopecias, asking what happens to the stem cells of the hair follicle and how they may contribute to the progression of these diseases. Bulge-resident cells are lost (leading to loss of capacity for hair growth) from the follicle either by inflammatory-mediate apoptosis or through epigenetic reprogramming to assume a mesenchymal-like identity. What proportion of bulge cells is lost to which process is unknown and probably differs depending on the individual PCA and its specific inflammatory cell infiltrate. The formation of fibroblast-like cells from follicular stem cells may also mean that the cells of the bulge have a direct role in the pathogenesis. The identification of specific cells involved in the pathogenesis of these diseases could provide unique diagnostic and therapeutic opportunities to prevent disease progression by preventing EMT and specific pro-fibrotic signals.
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Affiliation(s)
- Richard P Halley-Stott
- Faculty of Health Sciences, University of Cape Town, Anzio Road, Observatory, Cape Town, South Africa.
| | - Henry A Adeola
- Hair and Skin Research Laboratory, Groote Schuur Hospital, Cape Town, South Africa
| | - Nonhlanhla P Khumalo
- Hair and Skin Research Laboratory, Groote Schuur Hospital, Cape Town, South Africa
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3
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Halley-Stott RP. Nuclear Reprogramming and Mitosis--how does mitosis enhance changes in gene expression? Transcription 2015; 6:17-20. [PMID: 25668203 DOI: 10.1080/21541264.2015.1014262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Abstract
Nuclear reprogramming changes the identity of cells by changing gene expression programmes. Two recent pieces of work have highlighted the role that mitosis plays in enhancing the success of nuclear reprogramming. This Point of View article examines this work in the context of nuclear reprogramming.
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Affiliation(s)
- Richard P Halley-Stott
- a Faculty of Health Sciences, University of Cape Town , Anzio Road, Observatory , Cape Town , South Africa
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4
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Jullien J, Miyamoto K, Pasque V, Allen GE, Bradshaw CR, Garrett NJ, Halley-Stott RP, Kimura H, Ohsumi K, Gurdon JB. Hierarchical molecular events driven by oocyte-specific factors lead to rapid and extensive reprogramming. Mol Cell 2014; 55:524-36. [PMID: 25066233 PMCID: PMC4156308 DOI: 10.1016/j.molcel.2014.06.024] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Revised: 05/15/2014] [Accepted: 06/12/2014] [Indexed: 12/31/2022]
Abstract
Nuclear transfer to oocytes is an efficient way to transcriptionally reprogram somatic nuclei, but its mechanisms remain unclear. Here, we identify a sequence of molecular events that leads to rapid transcriptional reprogramming of somatic nuclei after transplantation to Xenopus oocytes. RNA-seq analyses reveal that reprogramming by oocytes results in a selective switch in transcription toward an oocyte rather than pluripotent type, without requiring new protein synthesis. Time-course analyses at the single-nucleus level show that transcriptional reprogramming is induced in most transplanted nuclei in a highly hierarchical manner. We demonstrate that an extensive exchange of somatic- for oocyte-specific factors mediates reprogramming and leads to robust oocyte RNA polymerase II binding and phosphorylation on transplanted chromatin. Moreover, genome-wide binding of oocyte-specific linker histone B4 supports its role in transcriptional reprogramming. Thus, our study reveals the rapid, abundant, and stepwise loading of oocyte-specific factors onto somatic chromatin as important determinants for successful reprogramming. Xenopus oocytes induce an oocyte transcription pattern in mouse nuclei in 2 days Reprogramming requires a switch from somatic to oocyte transcriptional components Unusually high amounts of oocyte-derived RNA polymerase II drive reprogramming The pattern of oocyte linker histone binding to somatic chromatin is revealed
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Affiliation(s)
- Jerome Jullien
- Wellcome Trust/Cancer Research UK Gurdon Institute, Tennis Court Road, Cambridge CB2 1QN, UK; Department of Zoology, University of Cambridge, Cambridge CB2 1QN, UK
| | - Kei Miyamoto
- Wellcome Trust/Cancer Research UK Gurdon Institute, Tennis Court Road, Cambridge CB2 1QN, UK; Department of Zoology, University of Cambridge, Cambridge CB2 1QN, UK
| | - Vincent Pasque
- Wellcome Trust/Cancer Research UK Gurdon Institute, Tennis Court Road, Cambridge CB2 1QN, UK; Department of Zoology, University of Cambridge, Cambridge CB2 1QN, UK
| | - George E Allen
- Wellcome Trust/Cancer Research UK Gurdon Institute, Tennis Court Road, Cambridge CB2 1QN, UK; Department of Zoology, University of Cambridge, Cambridge CB2 1QN, UK
| | - Charles R Bradshaw
- Wellcome Trust/Cancer Research UK Gurdon Institute, Tennis Court Road, Cambridge CB2 1QN, UK; Department of Zoology, University of Cambridge, Cambridge CB2 1QN, UK
| | - Nigel J Garrett
- Wellcome Trust/Cancer Research UK Gurdon Institute, Tennis Court Road, Cambridge CB2 1QN, UK; Department of Zoology, University of Cambridge, Cambridge CB2 1QN, UK
| | - Richard P Halley-Stott
- Wellcome Trust/Cancer Research UK Gurdon Institute, Tennis Court Road, Cambridge CB2 1QN, UK; Department of Zoology, University of Cambridge, Cambridge CB2 1QN, UK
| | - Hiroshi Kimura
- Graduate School of Frontier Biosciences, Osaka University, Suita 565-0871, Japan
| | - Keita Ohsumi
- Laboratory of Molecular Genetics, Division of Biological Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602, Japan
| | - John B Gurdon
- Wellcome Trust/Cancer Research UK Gurdon Institute, Tennis Court Road, Cambridge CB2 1QN, UK; Department of Zoology, University of Cambridge, Cambridge CB2 1QN, UK.
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5
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Christophorou MA, Castelo-Branco G, Halley-Stott RP, Oliveira CS, Loos R, Radzisheuskaya A, Mowen KA, Bertone P, Silva JCR, Zernicka-Goetz M, Nielsen ML, Gurdon JB, Kouzarides T. Citrullination regulates pluripotency and histone H1 binding to chromatin. Nature 2014; 507:104-8. [PMID: 24463520 PMCID: PMC4843970 DOI: 10.1038/nature12942] [Citation(s) in RCA: 280] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2012] [Accepted: 12/06/2013] [Indexed: 12/23/2022]
Abstract
Citrullination is the post-translational conversion of an arginine residue within a protein to the non-coded amino acid citrulline. This modification leads to the loss of a positive charge and reduction in hydrogen-bonding ability. It is carried out by a small family of tissue-specific vertebrate enzymes called peptidylarginine deiminases (PADIs) and is associated with the development of diverse pathological states such as autoimmunity, cancer, neurodegenerative disorders, prion diseases and thrombosis. Nevertheless, the physiological functions of citrullination remain ill-defined, although citrullination of core histones has been linked to transcriptional regulation and the DNA damage response. PADI4 (also called PAD4 or PADV), the only PADI with a nuclear localization signal, was previously shown to act in myeloid cells where it mediates profound chromatin decondensation during the innate immune response to infection. Here we show that the expression and enzymatic activity of Padi4 are also induced under conditions of ground-state pluripotency and during reprogramming in mouse. Padi4 is part of the pluripotency transcriptional network, binding to regulatory elements of key stem-cell genes and activating their expression. Its inhibition lowers the percentage of pluripotent cells in the early mouse embryo and significantly reduces reprogramming efficiency. Using an unbiased proteomic approach we identify linker histone H1 variants, which are involved in the generation of compact chromatin, as novel PADI4 substrates. Citrullination of a single arginine residue within the DNA-binding site of H1 results in its displacement from chromatin and global chromatin decondensation. Together, these results uncover a role for citrullination in the regulation of pluripotency and provide new mechanistic insights into how citrullination regulates chromatin compaction.
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Affiliation(s)
- Maria A Christophorou
- 1] The Gurdon Institute, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK [2]
| | - Gonçalo Castelo-Branco
- 1] The Gurdon Institute, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK [2] Laboratory of Molecular Neurobiology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, SE-17177 Stockholm, Sweden [3]
| | - Richard P Halley-Stott
- 1] The Gurdon Institute, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK [2] Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
| | - Clara Slade Oliveira
- 1] The Gurdon Institute, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK [2] EMBRAPA Dairy Cattle Research Center, Juiz de Fora, Brazil [3] Department of Physiology, Development and Neuroscience, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK
| | - Remco Loos
- European Molecular Biology Laboratory, European Bioinformatics Institute, Wellcome Trust Genome Campus, Cambridge CB10 1SD, UK
| | - Aliaksandra Radzisheuskaya
- 1] Wellcome Trust-Medical Research Council Cambridge Stem Cell Institute, University of Cambridge, Tennis Court Road, Cambridge CB2 1QR, UK [2] Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QR, UK
| | - Kerri A Mowen
- Department of Chemical Physiology, The Scripps Research Institute, La Jolla, California 92037, USA
| | - Paul Bertone
- 1] European Molecular Biology Laboratory, European Bioinformatics Institute, Wellcome Trust Genome Campus, Cambridge CB10 1SD, UK [2] Wellcome Trust-Medical Research Council Cambridge Stem Cell Institute, University of Cambridge, Tennis Court Road, Cambridge CB2 1QR, UK [3] Genome Biology and Developmental Biology Units, European Molecular Biology Laboratory, Meyerhofstraße 1, 69117 Heidelberg, Germany
| | - José C R Silva
- 1] Wellcome Trust-Medical Research Council Cambridge Stem Cell Institute, University of Cambridge, Tennis Court Road, Cambridge CB2 1QR, UK [2] Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QR, UK
| | - Magdalena Zernicka-Goetz
- 1] The Gurdon Institute, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK [2] Department of Physiology, Development and Neuroscience, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK
| | - Michael L Nielsen
- Department of proteomics, The Novo Nordisk Foundation Center for Protein Research, University of Copenhagen, Faculty of Health Sciences, Blegdamsvej 3b, DK-2200 Copenhagen, Denmark
| | - John B Gurdon
- 1] The Gurdon Institute, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK [2] Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
| | - Tony Kouzarides
- 1] The Gurdon Institute, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK [2] Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK
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6
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Abstract
There is currently particular interest in the field of nuclear reprogramming, a process by which the identity of specialised cells may be changed, typically to an embryonic-like state. Reprogramming procedures provide insight into many mechanisms of fundamental cell biology and have several promising applications, most notably in healthcare through the development of human disease models and patient-specific tissue-replacement therapies. Here, we introduce the field of nuclear reprogramming and briefly discuss six of the procedures by which reprogramming may be experimentally performed: nuclear transfer to eggs or oocytes, cell fusion, extract treatment, direct reprogramming to pluripotency and transdifferentiation.
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Affiliation(s)
- Richard P Halley-Stott
- The Wellcome Trust/Cancer Research UK Gurdon Institute, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QN, UK.
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7
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Abstract
Epigenetic memory represents a natural mechanism whereby the identity of a cell is maintained through successive cell cycles, allowing the specification and maintenance of differentiation during development and in adult cells. Cancer is a loss or reversal of the stable differentiated state of adult cells and may be mediated in part by epigenetic changes. The identity of somatic cells can also be reversed experimentally by nuclear reprogramming. Nuclear reprogramming experiments reveal the mechanisms required to activate embryonic gene expression in adult cells and thus provide insight into the reversal of epigenetic memory. In this article, we will introduce epigenetic memory and the mechanisms by which it may operate. We limit our discussion primarily to the context of nuclear reprogramming and briefly discuss the relevance of memory and reprogramming to cancer biology.
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Affiliation(s)
- Richard P Halley-Stott
- The Wellcome Trust/Cancer Research UK Gurdon Institute, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QN United Kingdom
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8
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Pasque V, Radzisheuskaya A, Gillich A, Halley-Stott RP, Panamarova M, Zernicka-Goetz M, Surani MA, Silva JCR. Histone variant macroH2A marks embryonic differentiation in vivo and acts as an epigenetic barrier to induced pluripotency. J Cell Sci 2012; 125:6094-104. [PMID: 23077180 PMCID: PMC3585521 DOI: 10.1242/jcs.113019] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/24/2012] [Indexed: 01/05/2023] Open
Abstract
How cell fate becomes restricted during somatic cell differentiation is a long-lasting question in biology. Epigenetic mechanisms not present in pluripotent cells and acquired during embryonic development are expected to stabilize the differentiated state of somatic cells and thereby restrict their ability to convert to another fate. The histone variant macroH2A acts as a component of an epigenetic multilayer that heritably maintains the silent X chromosome and has been shown to restrict tumor development. Here we show that macroH2A marks the differentiated cell state during mouse embryogenesis. MacroH2A.1 was found to be present at low levels upon the establishment of pluripotency in the inner cell mass and epiblast, but it was highly enriched in the trophectoderm and differentiated somatic cells later in mouse development. Chromatin immunoprecipitation revealed that macroH2A.1 is incorporated in the chromatin of regulatory regions of pluripotency genes in somatic cells such as mouse embryonic fibroblasts and adult neural stem cells, but not in embryonic stem cells. Removal of macroH2A.1, macroH2A.2 or both increased the efficiency of induced pluripotency up to 25-fold. The obtained induced pluripotent stem cells reactivated pluripotency genes, silenced retroviral transgenes and contributed to chimeras. In addition, overexpression of macroH2A isoforms prevented efficient reprogramming of epiblast stem cells to naïve pluripotency. In summary, our study identifies for the first time a link between an epigenetic mark and cell fate restriction during somatic cell differentiation, which helps to maintain cell identity and antagonizes induction of a pluripotent stem cell state.
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Affiliation(s)
- Vincent Pasque
- Wellcome Trust Cancer Research UK Gurdon Institute, Tennis Court Road, Cambridge CB2 1QN, UK
- Department of Zoology, University of Cambridge, CB2 1QN Cambridge, UK
| | - Aliaksandra Radzisheuskaya
- Wellcome Trust - Medical Research Council Cambridge Stem Cell Institute and Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QR, UK
| | - Astrid Gillich
- Wellcome Trust Cancer Research UK Gurdon Institute, Tennis Court Road, Cambridge CB2 1QN, UK
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 1QN, UK
| | - Richard P. Halley-Stott
- Wellcome Trust Cancer Research UK Gurdon Institute, Tennis Court Road, Cambridge CB2 1QN, UK
- Department of Zoology, University of Cambridge, CB2 1QN Cambridge, UK
| | - Maryna Panamarova
- Wellcome Trust Cancer Research UK Gurdon Institute, Tennis Court Road, Cambridge CB2 1QN, UK
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 1QN, UK
| | - Magdalena Zernicka-Goetz
- Wellcome Trust Cancer Research UK Gurdon Institute, Tennis Court Road, Cambridge CB2 1QN, UK
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 1QN, UK
| | - M. Azim Surani
- Wellcome Trust Cancer Research UK Gurdon Institute, Tennis Court Road, Cambridge CB2 1QN, UK
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 1QN, UK
| | - José C. R. Silva
- Wellcome Trust - Medical Research Council Cambridge Stem Cell Institute and Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QR, UK
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9
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Abstract
Nucleocytoplasmic hybrid (cybrid) embryos result from the combination of the nucleus of one species, and the egg cytoplasm of another species. Cybrid embryos can be obtained either in the haploid state by the cross-fertilization or intra-cytoplasmic injection of an enucleated egg with sperm from another species, or in the diploid state by the technique of interspecies somatic cell nuclear transfer (iSCNT). Cybrids that originate from the combination of the nucleus and the cytoplasm of distantly related species commonly expire during early embryonic development, and the cause of this arrest is currently under investigation. Here we show that cells isolated from a Xenopus cybrid (Xenopus (Silurana) tropicalis haploid nucleus combined with Xenopus laevis egg cytoplasm) embryo are unable to proliferate and expand normally in vitro. We also provide evidence that the lack of nuclear donor species maternal poly(A)+ RNA-dependent factors in the recipient species egg may contribute to the developmental dead-end of distantly-related cybrid embryos. Overall, the data are consistent with the view that the development promoted by one species’ nucleus is dependent on the presence of maternally-derived, mRNA encoded, species-specific factors. These results also show that cybrid development can be improved without nuclear species mitochondria supplementation or replacement.
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Affiliation(s)
- Patrick Narbonne
- The Wellcome Trust/Cancer Research UK Gurdon Institute; The Henry Wellcome Building of Cancer and Developmental Biology; University of Cambridge; Cambridge, UK ; Department of Zoology; University of Cambridge; Cambridge, UK
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10
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Pasque V, Jullien J, Miyamoto K, Halley-Stott RP, Gurdon J. Epigenetic factors influencing resistance to nuclear reprogramming. Trends Genet 2011; 27:516-25. [PMID: 21940062 PMCID: PMC3814186 DOI: 10.1016/j.tig.2011.08.002] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2011] [Revised: 08/16/2011] [Accepted: 08/22/2011] [Indexed: 12/16/2022]
Abstract
Patient-specific somatic cell reprogramming is likely to have a large impact on medicine by providing a source of cells for disease modelling and regenerative medicine. Several strategies can be used to reprogram cells, yet they are generally characterised by a low reprogramming efficiency, reflecting the remarkable stability of the differentiated state. Transcription factors, chromatin modifications, and noncoding RNAs can increase the efficiency of reprogramming. However, the success of nuclear reprogramming is limited by epigenetic mechanisms that stabilise the state of gene expression in somatic cells and thereby resist efficient reprogramming. We review here the factors that influence reprogramming efficiency, especially those that restrict the natural reprogramming mechanisms of eggs and oocytes. We see this as a step towards understanding the mechanisms by which nuclear reprogramming takes place.
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Affiliation(s)
- Vincent Pasque
- Wellcome Trust/Cancer Research UK Gurdon Institute, The Henry Wellcome Building of Cancer and Developmental Biology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QN, UK
- Department of Zoology, University of Cambridge, Downing Street, Cambridge, CB2 3EJ, UK
| | - Jerome Jullien
- Wellcome Trust/Cancer Research UK Gurdon Institute, The Henry Wellcome Building of Cancer and Developmental Biology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QN, UK
- Department of Zoology, University of Cambridge, Downing Street, Cambridge, CB2 3EJ, UK
- These authors contributed equally to this work
| | - Kei Miyamoto
- Wellcome Trust/Cancer Research UK Gurdon Institute, The Henry Wellcome Building of Cancer and Developmental Biology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QN, UK
- Department of Zoology, University of Cambridge, Downing Street, Cambridge, CB2 3EJ, UK
- These authors contributed equally to this work
| | - Richard P. Halley-Stott
- Wellcome Trust/Cancer Research UK Gurdon Institute, The Henry Wellcome Building of Cancer and Developmental Biology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QN, UK
- Department of Zoology, University of Cambridge, Downing Street, Cambridge, CB2 3EJ, UK
- These authors contributed equally to this work
| | - J.B. Gurdon
- Wellcome Trust/Cancer Research UK Gurdon Institute, The Henry Wellcome Building of Cancer and Developmental Biology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QN, UK
- Department of Zoology, University of Cambridge, Downing Street, Cambridge, CB2 3EJ, UK
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11
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Pasque V, Halley-Stott RP, Gillich A, Garrett N, Gurdon JB. Epigenetic stability of repressed states involving the histone variant macroH2A revealed by nuclear transfer to Xenopus oocytes. Nucleus 2011; 2:533-9. [PMID: 22064467 PMCID: PMC3324342 DOI: 10.4161/nucl.2.6.17799] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
How various epigenetic mechanisms restrict chromatin plasticity to determine the stability of repressed genes is poorly understood. Nuclear transfer to Xenopus oocytes induces the transcriptional reactivation of previously silenced genes. Recent work suggests that it can be used to analyze the epigenetic stability of repressed states. The notion that the epigenetic state of genes is an important determinant of the efficiency of nuclear reprogramming is supported by the differential reprogramming of given genes from different starting epigenetic configurations. After nuclear transfer, transcription from the inactive X chromosome of post-implantation-derived epiblast stem cells is reactivated. However, the same chromosome is resistant to reactivation when embryonic fibroblasts are used. Here, we discuss different kinds of evidence that link the histone variant macroH2A to the increased stability of repressed states. We focus on developmentally regulated X chromosome inactivation and repression of autosomal pluripotency genes, where macroH2A may help maintain the long-term stability of the differentiated state of somatic cells.
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Affiliation(s)
- Vincent Pasque
- Wellcome Trust/Cancer Research UK Gurdon Institute, University of Cambridge, Cambridge, UK.
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Regnard GL, Halley-Stott RP, Tanzer FL, Hitzeroth II, Rybicki EP. High level protein expression in plants through the use of a novel autonomously replicating geminivirus shuttle vector. Plant Biotechnol J 2010; 8:38-46. [PMID: 19929900 DOI: 10.1111/j.1467-7652.2009.00462.x] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
We constructed a novel autonomously replicating gene expression shuttle vector, with the aim of developing a system for transiently expressing proteins at levels useful for commercial production of vaccines and other proteins in plants. The vector, pRIC, is based on the mild strain of the geminivirus Bean yellow dwarf virus (BeYDV-m) and is replicationally released into plant cells from a recombinant Agrobacterium tumefaciens Ti plasmid. pRIC differs from most other geminivirus-based vectors in that the BeYDV replication-associated elements were included in cis rather than from a co-transfected plasmid, while the BeYDV capsid protein (CP) and movement protein (MP) genes were replaced by an antigen encoding transgene expression cassette derived from the non-replicating A. tumefaciens vector, pTRAc. We tested vector efficacy in Nicotiana benthamiana by comparing transient cytoplasmic expression between pRIC and pTRAc constructs encoding either enhanced green fluorescent protein (EGFP) or the subunit vaccine antigens, human papillomavirus subtype 16 (HPV-16) major CP L1 and human immunodeficiency virus subtype C p24 antigen. The pRIC constructs were amplified in planta by up to two orders of magnitude by replication, while 50% more HPV-16 L1 and three- to seven-fold more EGFP and HIV-1 p24 were expressed from pRIC than from pTRAc. Vector replication was shown to be correlated with increased protein expression. We anticipate that this new high-yielding plant expression vector will contribute towards the development of a viable plant production platform for vaccine candidates and other pharmaceuticals.
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Affiliation(s)
- Guy L Regnard
- Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Observatory, South Africa
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Halley-Stott RP, Tanzer F, Martin DP, Rybicki EP. The complete nucleotide sequence of a mild strain of Bean yellow dwarf virus. Arch Virol 2007; 152:1237-40. [PMID: 17347772 DOI: 10.1007/s00705-006-0933-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2006] [Accepted: 12/21/2006] [Indexed: 10/23/2022]
Affiliation(s)
- R P Halley-Stott
- Department of Molecular and Cell Biology, Faculty of Science, University of Cape Town, Cape Town, South Africa
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