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Wang J, Zhou X, Han T, Zhang H. Epigenetic signatures of trophoblast lineage and their biological functions. Cells Dev 2024:203934. [PMID: 38942294 DOI: 10.1016/j.cdev.2024.203934] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Revised: 03/13/2024] [Accepted: 06/13/2024] [Indexed: 06/30/2024]
Abstract
Trophoblasts play a crucial role in embryo implantation and in interacting with the maternal uterus. The trophoblast lineage develops into a substantial part of the placenta, a temporary extra-embryonic organ, capable of undergoing distinctive epigenetic events during development. The critical role of trophoblast-specific epigenetic signatures in regulating placental development has become known, significantly advancing our understanding of trophoblast identity and lineage development. Scientific efforts are revealing how trophoblast-specific epigenetic signatures mediate stage-specific gene regulatory programming during the development of the trophoblast lineage. These epigenetic signatures have a significant impact on blastocyst formation, placental development, as well as the growth and survival of embryos and fetuses. In evolution, DNA hypomethylation in the trophoblast lineage is conserved, and there is a significant disparity in the control of epigenetic dynamics and the landscape of genomic imprinting. Scientists have used murine and human multipotent trophoblast cells as in vitro models to recapitulate the essential epigenetic processes of placental development. Here, we review the epigenetic signatures of the trophoblast lineage and their biological functions to enhance our understanding of placental evolution, development, and function.
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Affiliation(s)
- Jianqi Wang
- Chongqing Key Laboratory of Maternal and Fetal Medicine, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, China; Department of Obstetrics and Gynecology, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, China
| | - Xiaobo Zhou
- Chongqing Key Laboratory of Maternal and Fetal Medicine, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, China; Department of Reproductive Center, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, China
| | - Tingli Han
- Chongqing Key Laboratory of Maternal and Fetal Medicine, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, China; Joint International Research Laboratory of Reproduction and Development of Chinese Ministry of Education, Chongqing Medical University, 400016, China; The Center for Reproductive Medicine, Obstetrics and Gynecology Department, The Second Affiliated Hospital of Chongqing Medical University, Chongqing 400010, China.
| | - Hua Zhang
- Chongqing Key Laboratory of Maternal and Fetal Medicine, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, China; Department of Obstetrics and Gynecology, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, China; Joint International Research Laboratory of Reproduction and Development of Chinese Ministry of Education, Chongqing Medical University, 400016, China.
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Lehle JD, Lin YH, Gomez A, Chavez L, McCarrey JR. Endocrine disruptor-induced epimutagenesis in vitro : Insight into molecular mechanisms. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.05.574355. [PMID: 38746310 PMCID: PMC11092511 DOI: 10.1101/2024.01.05.574355] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2024]
Abstract
Endocrine disrupting chemicals (EDCs) such as bisphenol S (BPS) are xenobiotic compounds that can disrupt endocrine signaling following exposure due to steric similarities to endogenous hormones within the body. EDCs have been shown to induce disruptions in normal epigenetic programming (epimutations) that accompany dysregulation of normal gene expression patterns that appear to predispose disease states. Most interestingly, the prevalence of epimutations following exposure to many different EDCs often persists over multiple subsequent generations, even with no further exposure to the causative EDC. Many previous studies have described both the direct and prolonged effects of EDC exposure in animal models, but many questions remain about molecular mechanisms by which EDCs initially induce epimutations or contribute to the propagation of EDC-induced epimutations either within the exposed generation or to subsequent generations. Additional questions remain regarding the extent to which there may be differences in cell-type specific susceptibilities to various EDCs, and whether this susceptibility is correlative with expression of relevant hormone receptors and/or the location of relevant hormone response elements (HREs) in the genome. To address these questions, we exposed cultured mouse pluripotent (induced pluripotent stem [iPS]), somatic (Sertoli and granulosa), and germ (primordial germ cell like [PGCLC]) cells to BPS and measured changes in DNA methylation levels at the epigenomic level and gene expression at the transcriptomic level. We found that there was indeed a difference in cell-type specific susceptibility to EDC-induced epimutagenesis and that this susceptibility correlated with differential expression of relevant hormone receptors and, in many cases, tended to generate epimutations near relevant HREs within the genome. Additionally, however, we also found that BPS can induce epimutations in a cell type that does not express relevant receptors and in genomic regions that do not contain relevant HREs, suggesting that both canonical and non-canonical signaling mechanisms can be disrupted by BPS exposure. Most interestingly, we found that when iPS cells were exposed to BPS and then induced to differentiate into PGCLCs, the prevalence of epimutations and differentially expressed genes (DEGs) initially induced in the iPSCs was largely retained in the resulting PGCLCs, however, >90% of the specific epimutations and DEGs were not conserved but were rather replaced by novel epimutations and DEGs following the iPSC to PGCLC transition. These results are consistent with a unique concept that many EDC-induced epimutations may normally be corrected by germline and/or embryonic epigenetic reprogramming but that due to disruption of the underlying chromatin architecture induced by the EDC exposure, many novel epimutations may emerge during the reprogramming process as well. Thus, it appears that following exposure to a disruptive agent such as an EDC, a prevalence of epimutations may transcend epigenetic reprogramming even though most individual epimutations are not conserved during this process.
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de Castro RCF, Buranello TW, Recchia K, de Souza AF, Pieri NCG, Bressan FF. Emerging Contributions of Pluripotent Stem Cells to Reproductive Technologies in Veterinary Medicine. J Dev Biol 2024; 12:14. [PMID: 38804434 PMCID: PMC11130827 DOI: 10.3390/jdb12020014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2024] [Revised: 04/10/2024] [Accepted: 04/22/2024] [Indexed: 05/29/2024] Open
Abstract
The generation of mature gametes and competent embryos in vitro from pluripotent stem cells has been successfully achieved in a few species, mainly in mice, with recent advances in humans and scarce preliminary reports in other domestic species. These biotechnologies are very attractive as they facilitate the understanding of developmental mechanisms and stages that are generally inaccessible during early embryogenesis, thus enabling advanced reproductive technologies and contributing to the generation of animals of high genetic merit in a short period. Studies on the production of in vitro embryos in pigs and cattle are currently used as study models for humans since they present more similar characteristics when compared to rodents in both the initial embryo development and adult life. This review discusses the most relevant biotechnologies used in veterinary medicine, focusing on the generation of germ-cell-like cells in vitro through the acquisition of totipotent status and the production of embryos in vitro from pluripotent stem cells, thus highlighting the main uses of pluripotent stem cells in livestock species and reproductive medicine.
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Affiliation(s)
- Raiane Cristina Fratini de Castro
- Department of Surgery, Faculty of Veterinary Medicine and Animal Sciences, University of Sao Paulo, São Paulo 01001-010, SP, Brazil; (R.C.F.d.C.); (T.W.B.); (K.R.)
| | - Tiago William Buranello
- Department of Surgery, Faculty of Veterinary Medicine and Animal Sciences, University of Sao Paulo, São Paulo 01001-010, SP, Brazil; (R.C.F.d.C.); (T.W.B.); (K.R.)
| | - Kaiana Recchia
- Department of Surgery, Faculty of Veterinary Medicine and Animal Sciences, University of Sao Paulo, São Paulo 01001-010, SP, Brazil; (R.C.F.d.C.); (T.W.B.); (K.R.)
| | - Aline Fernanda de Souza
- Department of Veterinary Medicine, School of Animal Sciences and Food Engineering, University of Sao Paulo, Pirassununga 13635-900, SP, Brazil;
| | - Naira Caroline Godoy Pieri
- Department of Veterinary Medicine, School of Animal Sciences and Food Engineering, University of Sao Paulo, Pirassununga 13635-900, SP, Brazil;
| | - Fabiana Fernandes Bressan
- Department of Surgery, Faculty of Veterinary Medicine and Animal Sciences, University of Sao Paulo, São Paulo 01001-010, SP, Brazil; (R.C.F.d.C.); (T.W.B.); (K.R.)
- Department of Veterinary Medicine, School of Animal Sciences and Food Engineering, University of Sao Paulo, Pirassununga 13635-900, SP, Brazil;
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Song QH, Zhao KX, Huang S, Chen T, He L. Escape from X-chromosome inactivation and sex differences in Alzheimer's disease. Rev Neurosci 2024; 35:341-354. [PMID: 38157427 DOI: 10.1515/revneuro-2023-0108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Accepted: 11/24/2023] [Indexed: 01/03/2024]
Abstract
Sex differences exist in the onset and progression of Alzheimer's disease. Globally, women have a higher prevalence, while men with Alzheimer's disease experience earlier mortality and more pronounced cognitive decline than women. The cause of sex differences in Alzheimer's disease remains unclear. Accumulating evidence suggests the potential role of X-linked genetic factors in the sex difference of Alzheimer's disease (AD). During embryogenesis, a remarkable process known as X-chromosome inactivation (XCI) occurs in females, leading to one of the X chromosomes undergoing transcriptional inactivation, which balances the effects of two X chromosomes in females. Nevertheless, certain genes exceptionally escape from XCI, which provides a basis for dual expression dosage of specific genes in females. Based on recent research findings, we explore key escape genes and their potential therapeutic use associated with Alzheimer's disease. Also, we discuss their possible role in driving the sex differences in Alzheimer's disease. This will provide new perspectives for precision medicine and gender-specific treatment of AD.
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Affiliation(s)
- Qing-Hua Song
- Department of Pharmacology, China Pharmaceutical University, No. 24 Tong Jia Xiang, Nanjing 210009, Jiangsu Province, China
| | - Ke-Xuan Zhao
- Department of Pharmacology, China Pharmaceutical University, No. 24 Tong Jia Xiang, Nanjing 210009, Jiangsu Province, China
| | - Shuai Huang
- Department of Pharmacology, China Pharmaceutical University, No. 24 Tong Jia Xiang, Nanjing 210009, Jiangsu Province, China
| | - Tong Chen
- Department of Pharmacology, China Pharmaceutical University, No. 24 Tong Jia Xiang, Nanjing 210009, Jiangsu Province, China
| | - Ling He
- Department of Pharmacology, China Pharmaceutical University, No. 24 Tong Jia Xiang, Nanjing 210009, Jiangsu Province, China
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Hauth A, Panten J, Kneuss E, Picard C, Servant N, Rall I, Pérez-Rico YA, Clerquin L, Servaas N, Villacorta L, Jung F, Luong C, Chang HY, Zaugg JB, Stegle O, Odom DT, Loda A, Heard E. Escape from X inactivation is directly modulated by levels of Xist non-coding RNA. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.22.581559. [PMID: 38559194 PMCID: PMC10979913 DOI: 10.1101/2024.02.22.581559] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
In placental females, one copy of the two X chromosomes is largely silenced during a narrow developmental time window, in a process mediated by the non-coding RNA Xist1. Here, we demonstrate that Xist can initiate X-chromosome inactivation (XCI) well beyond early embryogenesis. By modifying its endogenous level, we show that Xist has the capacity to actively silence genes that escape XCI both in neuronal progenitor cells (NPCs) and in vivo, in mouse embryos. We also show that Xist plays a direct role in eliminating TAD-like structures associated with clusters of escapee genes on the inactive X chromosome, and that this is dependent on Xist's XCI initiation partner, SPEN2. We further demonstrate that Xist's function in suppressing gene expression of escapees and topological domain formation is reversible for up to seven days post-induction, but that sustained Xist up-regulation leads to progressively irreversible silencing and CpG island DNA methylation of facultative escapees. Thus, the distinctive transcriptional and regulatory topologies of the silenced X chromosome is actively, directly - and reversibly - controlled by Xist RNA throughout life.
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Affiliation(s)
- Antonia Hauth
- European Molecular Biology Laboratory, Directors' Research, 69117 Heidelberg, Germany
- Collaboration for joint PhD degree between EMBL and Heidelberg University, Germany
| | - Jasper Panten
- Division of Regulatory Genomics and Cancer Evolution, German Cancer Research Centre (DKFZ), 69120, Heidelberg, Germany
- Division of Computational Genomics and Systems Genetics, German Cancer Research Centre (DKFZ), 69120, Heidelberg, Germany
- Faculty of Biosciences, Heidelberg University, 69117, Heidelberg, Germany
| | - Emma Kneuss
- European Molecular Biology Laboratory, Directors' Research, 69117 Heidelberg, Germany
| | - Christel Picard
- European Molecular Biology Laboratory, Directors' Research, 69117 Heidelberg, Germany
- Present address: Institute of Molecular Genetics of Montpellier University of Montpellier, CNRS, 34090 Montpellier, France
| | - Nicolas Servant
- Bioinformatics and Computational Systems Biology of Cancer, INSERM U900, Paris 75005, France
| | - Isabell Rall
- European Molecular Biology Laboratory, Directors' Research, 69117 Heidelberg, Germany
- Present address: Institute of Human Biology (IHB), Roche Innovation Center Basel, 4070 Basel, Switzerland
| | - Yuvia A Pérez-Rico
- European Molecular Biology Laboratory, Directors' Research, 69117 Heidelberg, Germany
| | - Lena Clerquin
- European Molecular Biology Laboratory, Directors' Research, 69117 Heidelberg, Germany
| | - Nila Servaas
- European Molecular Biology Laboratory, Structural and Computational Biology Unit, 69117 Heidelberg, Germany
| | - Laura Villacorta
- European Molecular Biology Laboratory, Genomics Core Facility, 69117 Heidelberg, Germany
| | - Ferris Jung
- European Molecular Biology Laboratory, Genomics Core Facility, 69117 Heidelberg, Germany
| | - Christy Luong
- Center for Personal Dynamic Regulomes, Stanford University, Stanford, CA 94305, USA
| | - Howard Y Chang
- Center for Personal Dynamic Regulomes, Stanford University, Stanford, CA 94305, USA
- Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Judith B Zaugg
- European Molecular Biology Laboratory, Structural and Computational Biology Unit, 69117 Heidelberg, Germany
- Molecular Medicine Partnership Unit, EMBL-University of Heidelberg, Heidelberg, Germany
| | - Oliver Stegle
- European Molecular Biology Laboratory, Genome Biology Unit, 69117 Heidelberg, Germany
- Division of Computational Genomics and Systems Genetics, German Cancer Research Centre (DKFZ), 69120, Heidelberg, Germany
| | - Duncan T Odom
- Division of Regulatory Genomics and Cancer Evolution, German Cancer Research Centre (DKFZ), 69120, Heidelberg, Germany
- Faculty of Biosciences, Heidelberg University, 69117, Heidelberg, Germany
- Cancer Research UK Cambridge Institute, University of Cambridge, Cambridge, UK
| | - Agnese Loda
- European Molecular Biology Laboratory, Directors' Research, 69117 Heidelberg, Germany
| | - Edith Heard
- European Molecular Biology Laboratory, Directors' Research, 69117 Heidelberg, Germany
- Collège de France, Paris 75005, France
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Li Y, Mo Y, Chen C, He J, Guo Z. Research advances of polycomb group proteins in regulating mammalian development. Front Cell Dev Biol 2024; 12:1383200. [PMID: 38505258 PMCID: PMC10950033 DOI: 10.3389/fcell.2024.1383200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2024] [Accepted: 02/26/2024] [Indexed: 03/21/2024] Open
Abstract
Polycomb group (PcG) proteins are a subset of epigenetic factors that are highly conserved throughout evolution. In mammals, PcG proteins can be classified into two muti-proteins complexes: Polycomb repressive complex 1 (PRC1) and PRC2. Increasing evidence has demonstrated that PcG complexes play critical roles in the regulation of gene expression, genomic imprinting, chromosome X-inactivation, and chromatin structure. Accordingly, the dysfunction of PcG proteins is tightly orchestrated with abnormal developmental processes. Here, we summarized and discussed the current knowledge of the biochemical and molecular functions of PcG complexes, especially the PRC1 and PRC2 in mammalian development including embryonic development and tissue development, which will shed further light on the deep understanding of the basic knowledge of PcGs and their functions for reproductive health and developmental disorders.
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Affiliation(s)
| | | | | | - Jin He
- Department of Obstetrics and Gynecology, The First Hospital of Jilin University, Changchun, Jilin, China
| | - Zhiheng Guo
- Department of Obstetrics and Gynecology, The First Hospital of Jilin University, Changchun, Jilin, China
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Malcore RM, Kalantry S. A Comparative Analysis of Mouse Imprinted and Random X-Chromosome Inactivation. EPIGENOMES 2024; 8:8. [PMID: 38390899 PMCID: PMC10885068 DOI: 10.3390/epigenomes8010008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2024] [Revised: 02/01/2024] [Accepted: 02/06/2024] [Indexed: 02/24/2024] Open
Abstract
The mammalian sexes are distinguished by the X and Y chromosomes. Whereas males harbor one X and one Y chromosome, females harbor two X chromosomes. To equalize X-linked gene expression between the sexes, therian mammals have evolved X-chromosome inactivation as a dosage compensation mechanism. During X-inactivation, most genes on one of the two X chromosomes in females are transcriptionally silenced, thus equalizing X-linked gene expression between the sexes. Two forms of X-inactivation characterize eutherian mammals, imprinted and random. Imprinted X-inactivation is defined by the exclusive inactivation of the paternal X chromosome in all cells, whereas random X-inactivation results in the silencing of genes on either the paternal or maternal X chromosome in individual cells. Both forms of X-inactivation have been studied intensively in the mouse model system, which undergoes both imprinted and random X-inactivation early in embryonic development. Stable imprinted and random X-inactivation requires the induction of the Xist long non-coding RNA. Following its induction, Xist RNA recruits proteins and complexes that silence genes on the inactive-X. In this review, we present a current understanding of the mechanisms of Xist RNA induction, and, separately, the establishment and maintenance of gene silencing on the inactive-X by Xist RNA during imprinted and random X-inactivation.
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Affiliation(s)
| | - Sundeep Kalantry
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, MI 48105, USA
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Richardson V, Engel N, Kulathinal RJ. Comparative developmental genomics of sex-biased gene expression in early embryogenesis across mammals. Biol Sex Differ 2023; 14:30. [PMID: 37208698 DOI: 10.1186/s13293-023-00520-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Accepted: 05/15/2023] [Indexed: 05/21/2023] Open
Abstract
BACKGROUND Mammalian gonadal sex is determined by the presence or absence of a Y chromosome and the subsequent production of sex hormones contributes to secondary sexual differentiation. However, sex chromosome-linked genes encoding dosage-sensitive transcription and epigenetic factors are expressed well before gonad formation and have the potential to establish sex-biased expression that persists beyond the appearance of gonadal hormones. Here, we apply a comparative bioinformatics analysis on a pair of published single-cell datasets from mouse and human during very early embryogenesis-from two-cell to pre-implantation stages-to characterize sex-specific signals and to assess the degree of conservation among early acting sex-specific genes and pathways. RESULTS Clustering and regression analyses of gene expression across samples reveal that sex initially plays a significant role in overall gene expression patterns at the earliest stages of embryogenesis which potentially may be the byproduct of signals from male and female gametes during fertilization. Although these transcriptional sex effects rapidly diminish, sex-biased genes appear to form sex-specific protein-protein interaction networks across pre-implantation stages in both mammals providing evidence that sex-biased expression of epigenetic enzymes may establish sex-specific patterns that persist beyond pre-implantation. Non-negative matrix factorization (NMF) on male and female transcriptomes generated clusters of genes with similar expression patterns across sex and developmental stages, including post-fertilization, epigenetic, and pre-implantation ontologies conserved between mouse and human. While the fraction of sex-differentially expressed genes (sexDEGs) in early embryonic stages is similar and functional ontologies are conserved, the genes involved are generally different in mouse and human. CONCLUSIONS This comparative study uncovers much earlier than expected sex-specific signals in mouse and human embryos that pre-date hormonal signaling from the gonads. These early signals are diverged with respect to orthologs yet conserved in terms of function with important implications in the use of genetic models for sex-specific disease.
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Affiliation(s)
- Victorya Richardson
- Department of Biology, Temple University, 1900 N. 12th Street, Philadelphia, PA, 19122, USA
| | - Nora Engel
- Department of Cancer Biology, Lewis Katz School of Medicine, Fels Cancer Institute for Personalized Medicine, Temple University, 3400 N. Broad Street, Philadelphia, PA, 19140, USA.
| | - Rob J Kulathinal
- Department of Biology, Temple University, 1900 N. 12th Street, Philadelphia, PA, 19122, USA.
- Institute for Genomics and Evolutionary Medicine, Temple University, Philadelphia, PA, 19122, USA.
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Miquel CH, Faz-Lopez B, Guéry JC. Influence of X chromosome in sex-biased autoimmune diseases. J Autoimmun 2023; 137:102992. [PMID: 36641351 DOI: 10.1016/j.jaut.2023.102992] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Accepted: 01/03/2023] [Indexed: 01/13/2023]
Abstract
Females have better ability to resolve infections, compared to males, but also, a greater susceptibility to develop autoimmunity. Besides the initial interest on the contribution of sex-steroid hormone signaling, the role of genetic factors linked to X chromosome has recently focused much attention. In human and mouse, the number of X chromosomes, rather than sex-steroid hormones, have been found associated with higher risk or susceptibility to develop autoimmunity, particularly rheumatic diseases, such as SLE, Sjögren's syndrome or Scleroderma. For all of these diseases, the Toll-like receptor TLR7 and TLR8, encoded on the same locus in the human Xp, have been demonstrated to be causal in disease development through gene dosage effect or gain of function mutations. During embryonic development in female mammals, one X chromosome is stochastically inactivated to balance X-linked gene expression between males and females, a process known as X chromosome inactivation (XCI). Nevertheless, some genes including immune related genes can escape XCI to variable degree and penetrance, resulting in a bi-allelic expression in some immune cells, such as TLR7. Because tight regulation of TLR expression is necessary for a healthy, self-tolerant immune environment, XCI escape has been proposed as a mechanism contributing to this sexual dimorphism. In this review, we will summarize general mechanisms of XCI, and describe the known escapee's genes in immune cells, the cellular diversity created by such mechanisms and its potential implication in autoimmune diseases, with a particular focus on the X-linked genes and immune cell populations involved in SLE. Whether dysregulated expression of X-linked genes could contribute to the enhanced susceptibility of females to develop such diseases remains to be proven. Shedding lights onto the X-linked genetic mechanisms contributing to modulation of immune cell functions will undoubtedly provide new insights into the intricate mechanisms underlying sex differences in immunity and autoimmunity.
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Affiliation(s)
- Charles-Henry Miquel
- Toulouse Institute for Infectious and Inflammatory Diseases (INFINITY), Université de Toulouse, INSERM, CNRS, UPS, 31300, France; Arthritis R&D, Neuilly-Sur-Seine, France
| | - Berenice Faz-Lopez
- Toulouse Institute for Infectious and Inflammatory Diseases (INFINITY), Université de Toulouse, INSERM, CNRS, UPS, 31300, France
| | - Jean-Charles Guéry
- Toulouse Institute for Infectious and Inflammatory Diseases (INFINITY), Université de Toulouse, INSERM, CNRS, UPS, 31300, France.
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Anesi N, Miquel CH, Laffont S, Guéry JC. The Influence of Sex Hormones and X Chromosome in Immune Responses. Curr Top Microbiol Immunol 2023; 441:21-59. [PMID: 37695424 DOI: 10.1007/978-3-031-35139-6_2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/12/2023]
Abstract
Males and females differ in their susceptibility to develop autoimmunity and allergy but also in their capacity to cope with infections and cancers. Cellular targets and molecular pathways underlying sexual dimorphism in immunity have started to emerge and appeared multifactorial. It became increasingly clear that sex-linked biological factors have important impact on the development, tissue maintenance and effector function acquisition of distinct immune cell populations, thereby regulating multiple layers of innate or adaptive immunity through distinct mechanisms. This review discusses the recent development in our understanding of the cell-intrinsic actions of biological factors linked to sex, sex hormones and sex chromosome complement, on immune cells, which may account for the sex differences in susceptibility to autoimmune diseases and allergies, and the sex-biased responses in natural immunity and cancer.
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Affiliation(s)
- Nina Anesi
- Toulouse Institute for Infectious and Inflammatory Diseases (INFINITY), Université de Toulouse, INSERM, CNRS, UPS, 31300, Toulouse, France
| | - Charles-Henry Miquel
- Toulouse Institute for Infectious and Inflammatory Diseases (INFINITY), Université de Toulouse, INSERM, CNRS, UPS, 31300, Toulouse, France
| | - Sophie Laffont
- Toulouse Institute for Infectious and Inflammatory Diseases (INFINITY), Université de Toulouse, INSERM, CNRS, UPS, 31300, Toulouse, France
| | - Jean-Charles Guéry
- Toulouse Institute for Infectious and Inflammatory Diseases (INFINITY), Université de Toulouse, INSERM, CNRS, UPS, 31300, Toulouse, France.
- INSERM UMR1291, Centre Hospitalier Universitaire Purpan, Place du Dr. Baylac, 31024, Toulouse Cedex 3, France.
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Cosentino L, Zidda F, Dukal H, Witt SH, De Filippis B, Flor H. Low levels of Methyl-CpG binding protein 2 are accompanied by an increased vulnerability to the negative outcomes of stress exposure during childhood in healthy women. Transl Psychiatry 2022; 12:506. [PMID: 36481643 PMCID: PMC9731965 DOI: 10.1038/s41398-022-02259-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2021] [Revised: 11/15/2022] [Accepted: 11/17/2022] [Indexed: 12/13/2022] Open
Abstract
Numerous mental illnesses arise following stressful events in vulnerable individuals, with females being generally more affected than males. Adverse childhood experiences are known to increase the risk of developing psychopathologies and DNA methylation was demonstrated to drive the long-lasting effects of early life stress and promote stress susceptibility. Methyl-CpG binding protein 2 (MECP2), an X-linked reader of the DNA methylome, is altered in many mental disorders of stress origin, suggesting MECP2 as a marker of stress susceptibility; previous works also suggest a link between MECP2 and early stress experiences. The present work explored whether a reduced expression of MECP2 is paralleled by an increased vulnerability to the negative outcomes of stress exposure during childhood. To this aim, blood MECP2 mRNA levels were analyzed in 63 people without history of mental disorders and traits pertaining to depressive and anxiety symptom clusters were assessed as proxies of the vulnerability to develop stress-related disorders; stress exposure during childhood was also evaluated. Using structural equation modeling, we demonstrate that reduced MECP2 expression is accompanied by symptoms of anxiety/depression in association with exposure to stress in early life, selectively in healthy women. These results suggest a gender-specific involvement of MECP2 in the maladaptive outcomes of childhood adversities, and shed new light on the complex biology underlying gender bias in stress susceptibility.
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Affiliation(s)
- Livia Cosentino
- grid.416651.10000 0000 9120 6856Center for Behavioral Sciences and Mental Health, Istituto Superiore di Sanità, Roma, Italy ,grid.7700.00000 0001 2190 4373Institute of Cognitive and Clinical Neuroscience, Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Francesca Zidda
- grid.7700.00000 0001 2190 4373Institute of Cognitive and Clinical Neuroscience, Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Helene Dukal
- grid.7700.00000 0001 2190 4373Department of Genetic Epidemiology in Psychiatry, Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Stephanie H. Witt
- grid.7700.00000 0001 2190 4373Department of Genetic Epidemiology in Psychiatry, Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Bianca De Filippis
- Center for Behavioral Sciences and Mental Health, Istituto Superiore di Sanità, Roma, Italy.
| | - Herta Flor
- Institute of Cognitive and Clinical Neuroscience, Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany.
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12
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Keniry A, Jansz N, Hickey PF, Breslin KA, Iminitoff M, Beck T, Gouil Q, Ritchie ME, Blewitt ME. A method for stabilising the XX karyotype in female mESC cultures. Development 2022; 149:285125. [PMID: 36355065 PMCID: PMC10112917 DOI: 10.1242/dev.200845] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Accepted: 10/30/2022] [Indexed: 11/12/2022]
Abstract
Female mouse embryonic stem cells (mESCs) present differently from male mESCs in several fundamental ways; however, complications with their in vitro culture have resulted in an under-representation of female mESCs in the literature. Recent studies show that the second X chromosome in female, and more specifically the transcriptional activity from both of these chromosomes due to absent X chromosome inactivation, sets female and male mESCs apart. To avoid this undesirable state, female mESCs in culture preferentially adopt an XO karyotype, with this adaption leading to loss of their unique properties in favour of a state that is near indistinguishable from male mESCs. If female pluripotency is to be studied effectively in this system, it is crucial that high-quality cultures of XX mESCs are available. Here, we report a method for better maintaining XX female mESCs in culture that also stabilises the male karyotype and makes study of female-specific pluripotency more feasible.
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Affiliation(s)
- Andrew Keniry
- The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC 3052, Australia.,The Department of Medical Biology, University of Melbourne, Parkville, VIC 3010, Australia
| | - Natasha Jansz
- The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC 3052, Australia.,The Department of Medical Biology, University of Melbourne, Parkville, VIC 3010, Australia
| | - Peter F Hickey
- The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC 3052, Australia.,The Department of Medical Biology, University of Melbourne, Parkville, VIC 3010, Australia
| | - Kelsey A Breslin
- The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC 3052, Australia
| | - Megan Iminitoff
- The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC 3052, Australia.,The Department of Medical Biology, University of Melbourne, Parkville, VIC 3010, Australia
| | - Tamara Beck
- The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC 3052, Australia
| | - Quentin Gouil
- The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC 3052, Australia.,The Department of Medical Biology, University of Melbourne, Parkville, VIC 3010, Australia
| | - Matthew E Ritchie
- The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC 3052, Australia.,The Department of Medical Biology, University of Melbourne, Parkville, VIC 3010, Australia
| | - Marnie E Blewitt
- The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC 3052, Australia.,The Department of Medical Biology, University of Melbourne, Parkville, VIC 3010, Australia
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13
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Lyu Q, Yang Q, Hao J, Yue Y, Wang X, Tian J, An L. A small proportion of X-linked genes contribute to X chromosome upregulation in early embryos via BRD4-mediated transcriptional activation. Curr Biol 2022; 32:4397-4410.e5. [PMID: 36108637 DOI: 10.1016/j.cub.2022.08.059] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Revised: 06/30/2022] [Accepted: 08/19/2022] [Indexed: 02/08/2023]
Abstract
Females have two X chromosomes and males have only one in most mammals. X chromosome inactivation (XCI) occurs in females to equalize X-dosage between sexes. Besides, mammals also balance the dosage between X chromosomes and autosomes via X chromosome upregulation (XCU) to fine-tune X-linked expression and thus maintain genomic homeostasis. Despite some studies highlighting the importance of XCU in somatic cells, little is known about how XCU is achieved and its developmental role during early embryogenesis. Herein, using mouse preimplantation embryos as the model, we reported that XCU initially occurs upon major zygotic genome activation and co-regulates X-linked expression in cooperation with imprinted XCI during preimplantation development. An in-depth analysis further indicated, unexpectedly, only a small proportion of, but not X chromosome-wide, X-linked genes contribute greatly to XCU. Furthermore, we identified that bromodomain containing 4 (BRD4) plays a key role in the transcription activation of XCU during preimplantation development. BRD4 deficiency or inhibition caused an impaired XCU, thus leading to reduced developmental potential and mitochondrial dysfunctions of blastocysts. Our finding was also supported by the tight association of BRD4 dysregulation and XCU disruption in the pathology of cholangiocarcinoma. Thus, our results not only advanced the current knowledge of X-dosage compensation and provided a mechanism for understanding XCU initiation but also presented an important clue for understanding the developmental and pathological role of XCU.
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Affiliation(s)
- Qingji Lyu
- Key Laboratory of Animal Genetics, Breeding and Reproduction of the Ministry of Agriculture and Rural Affairs, National Engineering Laboratory for Animal Breeding, College of Animal Science and Technology, China Agricultural University, Beijing 100193, P.R. China
| | - Qianying Yang
- Key Laboratory of Animal Genetics, Breeding and Reproduction of the Ministry of Agriculture and Rural Affairs, National Engineering Laboratory for Animal Breeding, College of Animal Science and Technology, China Agricultural University, Beijing 100193, P.R. China
| | - Jia Hao
- Key Laboratory of Animal Genetics, Breeding and Reproduction of the Ministry of Agriculture and Rural Affairs, National Engineering Laboratory for Animal Breeding, College of Animal Science and Technology, China Agricultural University, Beijing 100193, P.R. China
| | - Yuan Yue
- Key Laboratory of Animal Genetics, Breeding and Reproduction of the Ministry of Agriculture and Rural Affairs, National Engineering Laboratory for Animal Breeding, College of Animal Science and Technology, China Agricultural University, Beijing 100193, P.R. China
| | - Xiaodong Wang
- Key Laboratory of Animal Genetics, Breeding and Reproduction of the Ministry of Agriculture and Rural Affairs, National Engineering Laboratory for Animal Breeding, College of Animal Science and Technology, China Agricultural University, Beijing 100193, P.R. China
| | - Jianhui Tian
- Key Laboratory of Animal Genetics, Breeding and Reproduction of the Ministry of Agriculture and Rural Affairs, National Engineering Laboratory for Animal Breeding, College of Animal Science and Technology, China Agricultural University, Beijing 100193, P.R. China
| | - Lei An
- Key Laboratory of Animal Genetics, Breeding and Reproduction of the Ministry of Agriculture and Rural Affairs, National Engineering Laboratory for Animal Breeding, College of Animal Science and Technology, China Agricultural University, Beijing 100193, P.R. China.
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14
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Wanigasuriya I, Kinkel SA, Beck T, Roper EA, Breslin K, Lee HJ, Keniry A, Ritchie ME, Blewitt ME, Gouil Q. Maternal SMCHD1 controls both imprinted Xist expression and imprinted X chromosome inactivation. Epigenetics Chromatin 2022; 15:26. [PMID: 35843975 PMCID: PMC9290310 DOI: 10.1186/s13072-022-00458-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Accepted: 06/21/2022] [Indexed: 12/13/2022] Open
Abstract
Embryonic development is dependent on the maternal supply of proteins through the oocyte, including factors setting up the adequate epigenetic patterning of the zygotic genome. We previously reported that one such factor is the epigenetic repressor SMCHD1, whose maternal supply controls autosomal imprinted expression in mouse preimplantation embryos and mid-gestation placenta. In mouse preimplantation embryos, X chromosome inactivation is also an imprinted process. Combining genomics and imaging, we show that maternal SMCHD1 is required not only for the imprinted expression of Xist in preimplantation embryos, but also for the efficient silencing of the inactive X in both the preimplantation embryo and mid-gestation placenta. These results expand the role of SMCHD1 in enforcing the silencing of Polycomb targets. The inability of zygotic SMCHD1 to fully restore imprinted X inactivation further points to maternal SMCHD1’s role in setting up the appropriate chromatin environment during preimplantation development, a critical window of epigenetic remodelling.
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Affiliation(s)
- Iromi Wanigasuriya
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia.,The Department of Medical Biology, The University of Melbourne, Parkville, Australia
| | - Sarah A Kinkel
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia.,The Department of Medical Biology, The University of Melbourne, Parkville, Australia
| | - Tamara Beck
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia.,The Department of Medical Biology, The University of Melbourne, Parkville, Australia
| | - Ellise A Roper
- The School of Biomedical Sciences and Pharmacy, The University of Newcastle, Newcastle, Australia
| | - Kelsey Breslin
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia.,The Department of Medical Biology, The University of Melbourne, Parkville, Australia
| | - Heather J Lee
- The School of Biomedical Sciences and Pharmacy, The University of Newcastle, Newcastle, Australia
| | - Andrew Keniry
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia.,The Department of Medical Biology, The University of Melbourne, Parkville, Australia
| | - Matthew E Ritchie
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia.,The Department of Medical Biology, The University of Melbourne, Parkville, Australia.,The Department of Mathematics and Statistics, The University of Melbourne, Parkville, Australia
| | - Marnie E Blewitt
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia. .,The Department of Medical Biology, The University of Melbourne, Parkville, Australia.
| | - Quentin Gouil
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia. .,The Department of Medical Biology, The University of Melbourne, Parkville, Australia.
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15
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Dossin F, Heard E. The Molecular and Nuclear Dynamics of X-Chromosome Inactivation. Cold Spring Harb Perspect Biol 2022; 14:a040196. [PMID: 34312245 PMCID: PMC9121902 DOI: 10.1101/cshperspect.a040196] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
In female eutherian mammals, dosage compensation of X-linked gene expression is achieved during development through transcriptional silencing of one of the two X chromosomes. Following X chromosome inactivation (XCI), the inactive X chromosome remains faithfully silenced throughout somatic cell divisions. XCI is dependent on Xist, a long noncoding RNA that coats and silences the X chromosome from which it is transcribed. Xist coating triggers a cascade of chromosome-wide changes occurring at the levels of transcription, chromatin composition, chromosome structure, and spatial organization within the nucleus. XCI has emerged as a paradigm for the study of such crucial nuclear processes and the dissection of their functional interplay. In the past decade, the advent of tools to characterize and perturb these processes have provided an unprecedented understanding into their roles during XCI. The mechanisms orchestrating the initiation of XCI as well as its maintenance are thus being unraveled, although many questions still remain. Here, we introduce key aspects of the XCI process and review the recent discoveries about its molecular basis.
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Affiliation(s)
- François Dossin
- European Molecular Biology Laboratory, Director's Unit, 69117 Heidelberg, Germany
| | - Edith Heard
- European Molecular Biology Laboratory, Director's Unit, 69117 Heidelberg, Germany
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16
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Mechanisms of Choice in X-Chromosome Inactivation. Cells 2022; 11:cells11030535. [PMID: 35159344 PMCID: PMC8833938 DOI: 10.3390/cells11030535] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 01/30/2022] [Accepted: 01/31/2022] [Indexed: 12/04/2022] Open
Abstract
Early in development, placental and marsupial mammals harbouring at least two X chromosomes per nucleus are faced with a choice that affects the rest of their lives: which of those X chromosomes to transcriptionally inactivate. This choice underlies phenotypical diversity in the composition of tissues and organs and in their response to the environment, and can determine whether an individual will be healthy or affected by an X-linked disease. Here, we review our current understanding of the process of choice during X-chromosome inactivation and its implications, focusing on the strategies evolved by different mammalian lineages and on the known and unknown molecular mechanisms and players involved.
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17
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Gene regulation in time and space during X-chromosome inactivation. Nat Rev Mol Cell Biol 2022; 23:231-249. [PMID: 35013589 DOI: 10.1038/s41580-021-00438-7] [Citation(s) in RCA: 85] [Impact Index Per Article: 42.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/18/2021] [Indexed: 12/21/2022]
Abstract
X-chromosome inactivation (XCI) is the epigenetic mechanism that ensures X-linked dosage compensation between cells of females (XX karyotype) and males (XY). XCI is essential for female embryos to survive through development and requires the accurate spatiotemporal regulation of many different factors to achieve remarkable chromosome-wide gene silencing. As a result of XCI, the active and inactive X chromosomes are functionally and structurally different, with the inactive X chromosome undergoing a major conformational reorganization within the nucleus. In this Review, we discuss the multiple layers of genetic and epigenetic regulation that underlie initiation of XCI during development and then maintain it throughout life, in light of the most recent findings in this rapidly advancing field. We discuss exciting new insights into the regulation of X inactive-specific transcript (XIST), the trigger and master regulator of XCI, and into the mechanisms and dynamics that underlie the silencing of nearly all X-linked genes. Finally, given the increasing interest in understanding the impact of chromosome organization on gene regulation, we provide an overview of the factors that are thought to reshape the 3D structure of the inactive X chromosome and of the relevance of such structural changes for XCI establishment and maintenance.
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18
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Okamoto I, Nakamura T, Sasaki K, Yabuta Y, Iwatani C, Tsuchiya H, Nakamura SI, Ema M, Yamamoto T, Saitou M. The X chromosome dosage compensation program during the development of cynomolgus monkeys. Science 2021; 374:eabd8887. [PMID: 34793202 DOI: 10.1126/science.abd8887] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
[Figure: see text].
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Affiliation(s)
- Ikuhiro Okamoto
- Institute for the Advanced Study of Human Biology (ASHBi), Kyoto University, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan.,Department of Anatomy and Cell Biology, Graduate School of Medicine, Kyoto University, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan
| | - Tomonori Nakamura
- Institute for the Advanced Study of Human Biology (ASHBi), Kyoto University, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan.,Department of Anatomy and Cell Biology, Graduate School of Medicine, Kyoto University, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan.,Hakubi Center for Advanced Research, Kyoto University, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan
| | - Kotaro Sasaki
- Department of Anatomy and Cell Biology, Graduate School of Medicine, Kyoto University, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan
| | - Yukihiro Yabuta
- Institute for the Advanced Study of Human Biology (ASHBi), Kyoto University, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan.,Department of Anatomy and Cell Biology, Graduate School of Medicine, Kyoto University, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan
| | - Chizuru Iwatani
- Research Center for Animal Life Science, Shiga University of Medical Science, Seta-Tsukinowa-cho, Otsu, Shiga 520-2192, Japan
| | - Hideaki Tsuchiya
- Research Center for Animal Life Science, Shiga University of Medical Science, Seta-Tsukinowa-cho, Otsu, Shiga 520-2192, Japan
| | - Shin-Ichiro Nakamura
- Research Center for Animal Life Science, Shiga University of Medical Science, Seta-Tsukinowa-cho, Otsu, Shiga 520-2192, Japan
| | - Masatsugu Ema
- Institute for the Advanced Study of Human Biology (ASHBi), Kyoto University, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan.,Research Center for Animal Life Science, Shiga University of Medical Science, Seta-Tsukinowa-cho, Otsu, Shiga 520-2192, Japan
| | - Takuya Yamamoto
- Institute for the Advanced Study of Human Biology (ASHBi), Kyoto University, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan.,Center for iPS Cell Research and Application (CiRA), Kyoto University, 53 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8507, Japan.,AMED-CREST, AMED, 1-7-1 Otemachi, Chiyoda-ku, Tokyo 100-0004, Japan.,Medical-Risk Avoidance Based on iPS Cells Team, RIKEN Center for Advanced Intelligence Project (AIP), Kyoto 606-8507, Japan
| | - Mitinori Saitou
- Institute for the Advanced Study of Human Biology (ASHBi), Kyoto University, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan.,Department of Anatomy and Cell Biology, Graduate School of Medicine, Kyoto University, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan.,Center for iPS Cell Research and Application (CiRA), Kyoto University, 53 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8507, Japan
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19
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Trigiante G, Blanes Ruiz N, Cerase A. Emerging Roles of Repetitive and Repeat-Containing RNA in Nuclear and Chromatin Organization and Gene Expression. Front Cell Dev Biol 2021; 9:735527. [PMID: 34722514 PMCID: PMC8552494 DOI: 10.3389/fcell.2021.735527] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Accepted: 09/09/2021] [Indexed: 12/14/2022] Open
Abstract
Genomic repeats have been intensely studied as regulatory elements controlling gene transcription, splicing and genome architecture. Our understanding of the role of the repetitive RNA such as the RNA coming from genomic repeats, or repetitive sequences embedded in mRNA/lncRNAs, in nuclear and cellular functions is instead still limited. In this review we discuss evidence supporting the multifaceted roles of repetitive RNA and RNA binding proteins in nuclear organization, gene regulation, and in the formation of dynamic membrane-less aggregates. We hope that our review will further stimulate research in the consolidating field of repetitive RNA biology.
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Affiliation(s)
| | | | - Andrea Cerase
- Centre for Genomics and Child Health, Barts and The London School of Medicine and Dentistry, Blizard Institute, Queen Mary University of London, London, United Kingdom
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20
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Abstract
Long non-coding RNA (lncRNA) Xist has emerged as a key modulator in dosage compensation by randomly inactivating one of the X chromosomes in mammals during embryonic development. Dysregulation of X chromosome inactivation (XCI) due to deletion of Xist has been proven to induce hematologic cancer in mice. However, this phenomenon is not consistent in humans as growing evidence suggests Xist can suppress or promote cancer growth in different organs of the human body. In this review, we discuss recent advances of XCI in human embryonic stem cells and provide an explanation for the seemingly contradictory roles of Xist in development of human cancer.
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Affiliation(s)
- Yung-Kang Chen
- School of Medicine, Taipei Medical University, Taipei, Taiwan.,Department of General Medicine, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Yun Yen
- Graduate Institute of Medical Informatics, Taipei Medical University, Taipei, Taiwan. .,TMU Research Center of Cancer Translational Medicine, Taipei Medical University, 250 Wuxing Street, Taipei City, 110, Taiwan. .,Taipei Municipal Wanfang Hospital, Taipei Medical University, Taipei, Taiwan. .,Program for Cancer Molecular Biology and Drug Discovery, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan.
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21
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Żylicz JJ, Heard E. Molecular Mechanisms of Facultative Heterochromatin Formation: An X-Chromosome Perspective. Annu Rev Biochem 2020; 89:255-282. [PMID: 32259458 DOI: 10.1146/annurev-biochem-062917-012655] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Facultative heterochromatin (fHC) concerns the developmentally regulated heterochromatinization of different regions of the genome and, in the case of the mammalian X chromosome and imprinted loci, of only one allele of a homologous pair. The formation of fHC participates in the timely repression of genes, by resisting strong trans activators. In this review, we discuss the molecular mechanisms underlying the establishment and maintenance of fHC in mammals using a mouse model. We focus on X-chromosome inactivation (XCI) as a paradigm for fHC but also relate it to genomic imprinting and homeobox (Hox) gene cluster repression. A vital role for noncoding transcription and/or transcripts emerges as the general principle of triggering XCI and canonical imprinting. However, other types of fHC are established through an unknown mechanism, independent of noncoding transcription (Hox clusters and noncanonical imprinting). We also extensively discuss polycomb-group repressive complexes (PRCs), which frequently play a vital role in fHC maintenance.
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Affiliation(s)
- Jan J Żylicz
- Mammalian Developmental Epigenetics Group, Institut Curie, CNRS UMR 3215, INSERM U934, PSL University, 75248 Paris Cedex 05, France.,Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3EL, United Kingdom
| | - Edith Heard
- Directors' Research, EMBL Heidelberg, 69117 Heidelberg, Germany;
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22
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Initiation of X Chromosome Inactivation during Bovine Embryo Development. Cells 2020; 9:cells9041016. [PMID: 32325818 PMCID: PMC7226380 DOI: 10.3390/cells9041016] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Revised: 04/13/2020] [Accepted: 04/16/2020] [Indexed: 02/06/2023] Open
Abstract
X-chromosome inactivation (XCI) is a developmental process that aims to equalize the dosage of X-linked gene products between XY males and XX females in eutherian mammals. In female mouse embryos, paternal XCI is initiated at the 4-cell stage; however, the X chromosome is reactivated in the inner cell mass cells of blastocysts, and random XCI is subsequently initiated in epiblast cells. However, recent findings show that the patterns of XCI are not conserved among mammals. In this study, we used quantitative RT-PCR and RNA in situ hybridization combined with immunofluorescence to investigate the pattern of XCI during bovine embryo development. Expression of XIST (X-inactive specific transcript) RNA was significantly upregulated at the morula stage. For the first time, we demonstrate that XIST accumulation in bovine embryos starts in nuclei of female morulae, but its colocalization with histone H3 lysine 27 trimethylation was first detected in day 7 blastocysts. Both in the inner cell mass and in putative epiblast precursors, we observed a proportion of cells with XIST RNA and H3K27me3 colocalization. Surprisingly, the onset of XCI did not lead to a global downregulation of X-linked genes, even in day 9 blastocysts. Together, our findings confirm that diverse patterns of XCI initiation exist among developing mammalian embryos.
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23
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Fang H, Disteche CM, Berletch JB. X Inactivation and Escape: Epigenetic and Structural Features. Front Cell Dev Biol 2019; 7:219. [PMID: 31632970 PMCID: PMC6779695 DOI: 10.3389/fcell.2019.00219] [Citation(s) in RCA: 79] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Accepted: 09/18/2019] [Indexed: 12/27/2022] Open
Abstract
X inactivation represents a complex multi-layer epigenetic mechanism that profoundly modifies chromatin composition and structure of one X chromosome in females. The heterochromatic inactive X chromosome adopts a unique 3D bipartite structure and a location close to the nuclear periphery or the nucleolus. X-linked lncRNA loci and their transcripts play important roles in the recruitment of proteins that catalyze chromatin and DNA modifications for silencing, as well as in the control of chromatin condensation and location of the inactive X chromosome. A subset of genes escapes X inactivation, raising questions about mechanisms that preserve their expression despite being embedded within heterochromatin. Escape gene expression differs between males and females, which can lead to physiological sex differences. We review recent studies that emphasize challenges in understanding the role of lncRNAs in the control of epigenetic modifications, structural features and nuclear positioning of the inactive X chromosome. Second, we highlight new findings about the distribution of genes that escape X inactivation based on single cell studies, and discuss the roles of escape genes in eliciting sex differences in health and disease.
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Affiliation(s)
- He Fang
- Department of Pathology, University of Washington, Seattle, WA, United States
| | - Christine M. Disteche
- Department of Pathology, University of Washington, Seattle, WA, United States
- Department of Medicine, University of Washington, Seattle, WA, United States
| | - Joel B. Berletch
- Department of Pathology, University of Washington, Seattle, WA, United States
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24
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Talon I, Janiszewski A, Chappell J, Vanheer L, Pasque V. Recent Advances in Understanding the Reversal of Gene Silencing During X Chromosome Reactivation. Front Cell Dev Biol 2019; 7:169. [PMID: 31552244 PMCID: PMC6733891 DOI: 10.3389/fcell.2019.00169] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Accepted: 08/07/2019] [Indexed: 12/24/2022] Open
Abstract
Dosage compensation between XX female and XY male cells is achieved by a process known as X chromosome inactivation (XCI) in mammals. XCI is initiated early during development in female cells and is subsequently stably maintained in most somatic cells. Despite its stability, the robust transcriptional silencing of XCI is reversible, in the embryo and also in a number of reprogramming settings. Although XCI has been intensively studied, the dynamics, factors, and mechanisms of X chromosome reactivation (XCR) remain largely unknown. In this review, we discuss how new sequencing technologies and reprogramming approaches have enabled recent advances that revealed the timing of transcriptional activation during XCR. We also discuss the factors and chromatin features that might be important to understand the dynamics and mechanisms of the erasure of transcriptional gene silencing on the inactive X chromosome (Xi).
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Affiliation(s)
| | | | | | | | - Vincent Pasque
- Department of Development and Regeneration, Leuven Stem Cell Institute, KU Leuven, Leuven, Belgium
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25
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Zhang MZ, Cao XM, Xu FQ, Liang XW, Fu LL, Li B, Liu WG, Li SG, Sun FZ, Huang XY, Huang WH. In the human sperm nucleus, nucleosomes form spatially restricted domains consistent with programmed nucleosome positioning. Biol Open 2019; 8:bio.041368. [PMID: 31262721 PMCID: PMC6679404 DOI: 10.1242/bio.041368] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
In human sperm, a fraction of its chromatin retains nucleosomes that are positioned on specific sequences containing genes and regulatory units essential for embryonic development. This nucleosome positioning (NP) feature provides an inherited epigenetic mark for sperm. However, it is not known whether there is a structural constraint for these nucleosomes and, if so, how they are localized in a three-dimensional (3D) context of the sperm nucleus. In this study, we examine the 3D organization of sperm chromatin and specifically determine its 3D localization of nucleosomes using structured illumination microscopy. A fraction of the sperm chromatin form nucleosome domains (NDs), visible as microscopic puncta ranging from 40 μm to 700 μm in diameter, and these NDs are precisely localized in the post acrosome region (PAR), outside the sperm's core chromatin. Further, NDs exist mainly in sperm from fertile men in a pilot survey with a small sample size. Together, this study uncovers a new spatially-restricted sub-nuclear structure containing NDs that are consistent with NPs of the sperm, which might represent a novel mark for healthy sperm in human.
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Affiliation(s)
- Mei-Zi Zhang
- Reproductive Medicine Center, Tianjin First central hospital, Tianjin 300192, China
| | - Xiao-Min Cao
- Reproductive Medicine Center, Tianjin First central hospital, Tianjin 300192, China
| | - Feng-Qin Xu
- Reproductive Medicine Center, Tianjin First central hospital, Tianjin 300192, China
| | - Xiao-Wei Liang
- Bejing Human Sperm Bank and National Research Institute for Family Planning, Beijing 100101, China
| | - Long-Long Fu
- Bejing Human Sperm Bank and National Research Institute for Family Planning, Beijing 100101, China
| | - Bao Li
- Department of Urology, Affiliated Hospital of Weifang Medical University, 261000 Weifang, Shandong, China
| | - Wei-Guang Liu
- Department of Urology, Affiliated Hospital of Weifang Medical University, 261000 Weifang, Shandong, China
| | - Shuo-Guo Li
- Center for Biological Imaging, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Fang-Zhen Sun
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Xiu-Ying Huang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Wei-Hong Huang
- Department of Urology, Affiliated Hospital of Weifang Medical University, 261000 Weifang, Shandong, China .,State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
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26
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A novel approach to differentiate rat embryonic stem cells in vitro reveals a role for RNF12 in activation of X chromosome inactivation. Sci Rep 2019; 9:6068. [PMID: 30988473 PMCID: PMC6465393 DOI: 10.1038/s41598-019-42246-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Accepted: 03/27/2019] [Indexed: 02/07/2023] Open
Abstract
X chromosome inactivation (XCI) is a mammalian specific, developmentally regulated process relying on several mechanisms including antisense transcription, non-coding RNA-mediated silencing, and recruitment of chromatin remodeling complexes. In vitro modeling of XCI, through differentiation of embryonic stem cells (ESCs), provides a powerful tool to study the dynamics of XCI, overcoming the need for embryos, and facilitating genetic modification of key regulatory players. However, to date, robust initiation of XCI in vitro has been mostly limited to mouse pluripotent stem cells. Here, we adapted existing protocols to establish a novel monolayer differentiation protocol for rat ESCs to study XCI. We show that differentiating rat ESCs properly downregulate pluripotency factor genes, and present female specific Xist RNA accumulation and silencing of X-linked genes. We also demonstrate that RNF12 seems to be an important player in regulation of initiation of XCI in rat, acting as an Xist activator. Our work provides the basis to investigate the mechanisms directing the XCI process in a model organism different from the mouse.
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27
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DNA Methylation Contributes to the Differential Expression Levels of Mecp2 in Male Mice Neurons and Astrocytes. Int J Mol Sci 2019; 20:ijms20081845. [PMID: 31013990 PMCID: PMC6514911 DOI: 10.3390/ijms20081845] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Revised: 04/09/2019] [Accepted: 04/11/2019] [Indexed: 02/01/2023] Open
Abstract
Methyl CpG binding protein-2 (MeCP2) isoforms (E1 and E2) are important epigenetic regulators in brain cells. Accordingly, MeCP2 loss- or gain-of-function mutation causes neurodevelopmental disorders, including Rett syndrome (RTT), MECP2 duplication syndrome (MDS), and autism spectrum disorders (ASD). Within different types of brain cells, highest MeCP2 levels are detected in neurons and the lowest in astrocytes. However, our current knowledge of Mecp2/MeCP2 regulatory mechanisms remains largely elusive. It appears that there is a sex-dependent effect in X-linked MeCP2-associated disorders, as RTT primarily affects females, whereas MDS is found almost exclusively in males. This suggests that Mecp2 expression levels in brain cells might be sex-dependent. Here, we investigated the sex- and cell type-specific expression of Mecp2 isoforms in male and female primary neurons and astrocytes isolated from the murine forebrain. Previously, we reported that DNA methylation of six Mecp2 regulatory elements correlated with Mecp2 levels in the brain. We now show that in male brain cells, DNA methylation is significantly correlated with the transcript expression of these two isoforms. We show that both Mecp2 isoforms are highly expressed in male neurons compared to male astrocytes, with Mecp2e1 expressed at higher levels than Mecp2e2. Our data indicate that higher DNA methylation at the Mecp2 regulatory element(s) is associated with lower levels of Mecp2 isoforms in male astrocytes compared to male neurons.
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28
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Harris C, Cloutier M, Trotter M, Hinten M, Gayen S, Du Z, Xie W, Kalantry S. Conversion of random X-inactivation to imprinted X-inactivation by maternal PRC2. eLife 2019; 8:e44258. [PMID: 30938678 PMCID: PMC6541438 DOI: 10.7554/elife.44258] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Accepted: 04/01/2019] [Indexed: 01/15/2023] Open
Abstract
Imprinted X-inactivation silences genes exclusively on the paternally-inherited X-chromosome and is a paradigm of transgenerational epigenetic inheritance in mammals. Here, we test the role of maternal vs. zygotic Polycomb repressive complex 2 (PRC2) protein EED in orchestrating imprinted X-inactivation in mouse embryos. In maternal-null (Eedm-/-) but not zygotic-null (Eed-/-) early embryos, the maternal X-chromosome ectopically induced Xist and underwent inactivation. Eedm-/- females subsequently stochastically silenced Xist from one of the two X-chromosomes and displayed random X-inactivation. This effect was exacerbated in embryos lacking both maternal and zygotic EED (Eedmz-/-), suggesting that zygotic EED can also contribute to the onset of imprinted X-inactivation. Xist expression dynamics in Eedm-/- embryos resemble that of early human embryos, which lack oocyte-derived maternal PRC2 and only undergo random X-inactivation. Thus, expression of PRC2 in the oocyte and transmission of the gene products to the embryo may dictate the occurrence of imprinted X-inactivation in mammals.
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Affiliation(s)
- Clair Harris
- Department of Human GeneticsUniversity of MichiganAnn ArborUnited States
| | - Marissa Cloutier
- Department of Human GeneticsUniversity of MichiganAnn ArborUnited States
| | - Megan Trotter
- Department of Human GeneticsUniversity of MichiganAnn ArborUnited States
| | - Michael Hinten
- Department of Human GeneticsUniversity of MichiganAnn ArborUnited States
| | - Srimonta Gayen
- Department of Human GeneticsUniversity of MichiganAnn ArborUnited States
| | - Zhenhai Du
- Center for Stem Cell Biology and Regenerative Medicine, MOE Key Laboratory of Bioinformatics, School of Life Sciences, THU-PKU Center for Life ScienceTsinghua UniversityBeijingChina
| | - Wei Xie
- Center for Stem Cell Biology and Regenerative Medicine, MOE Key Laboratory of Bioinformatics, School of Life Sciences, THU-PKU Center for Life ScienceTsinghua UniversityBeijingChina
| | - Sundeep Kalantry
- Department of Human GeneticsUniversity of MichiganAnn ArborUnited States
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29
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Peeters SB, Korecki AJ, Baldry SEL, Yang C, Tosefsky K, Balaton BP, Simpson EM, Brown CJ. How do genes that escape from X-chromosome inactivation contribute to Turner syndrome? AMERICAN JOURNAL OF MEDICAL GENETICS PART C-SEMINARS IN MEDICAL GENETICS 2019; 181:28-35. [PMID: 30779428 DOI: 10.1002/ajmg.c.31672] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Accepted: 12/09/2018] [Indexed: 12/30/2022]
Abstract
X-chromosome inactivation generally results in dosage equivalence for expression of X-linked genes between 46,XY males and 46,XX females. The 20-30% of genes that escape silencing are thus candidates for having a role in the phenotype of Turner syndrome. Understanding which genes escape from silencing, and how they avoid this chromosome-wide inactivation is therefore an important step toward understanding Turner Syndrome. We have examined the mechanism of escape using a previously reported knock-in of a BAC containing the human escape gene RPS4X in mouse. We now demonstrate that escape from inactivation for RPS4X is already established by embryonic Day 9.5, and that both silencing and escape are faithfully maintained across the lifespan. No overt abnormalities were observed for transgenic mice up to 1 year of age despite robust transcription of the human RPS4X gene with no detectable downregulation of the mouse homolog. However, there was no significant increase in protein levels, suggesting translational compensation in the mouse. Finally, while many of the protein-coding genes have been assessed for their inactivation status, less is known about the X-linked RNA genes, and we propose that for many microRNA genes their inactivation status can be predicted as they are intronic to genes for which the inactivation status is known.
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Affiliation(s)
- Samantha B Peeters
- Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia, Canada.,Molecular Epigenetics Group, Life Sciences Institute, Vancouver, British Columbia, Canada
| | - Andrea J Korecki
- Centre for Molecular Medicine and Therapeutics, BC Children's Hospital Research Institute, University of British Columbia, Vancouver, Canada
| | - Sarah E L Baldry
- Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia, Canada.,Molecular Epigenetics Group, Life Sciences Institute, Vancouver, British Columbia, Canada
| | - Christine Yang
- Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia, Canada.,Molecular Epigenetics Group, Life Sciences Institute, Vancouver, British Columbia, Canada
| | - Kira Tosefsky
- Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia, Canada.,Molecular Epigenetics Group, Life Sciences Institute, Vancouver, British Columbia, Canada
| | - Bradley P Balaton
- Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia, Canada.,Molecular Epigenetics Group, Life Sciences Institute, Vancouver, British Columbia, Canada
| | - Elizabeth M Simpson
- Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia, Canada.,Centre for Molecular Medicine and Therapeutics, BC Children's Hospital Research Institute, University of British Columbia, Vancouver, Canada
| | - Carolyn J Brown
- Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia, Canada.,Molecular Epigenetics Group, Life Sciences Institute, Vancouver, British Columbia, Canada
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30
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Wang X, Mittal P, Castro CA, Rajkovic G, Rajkovic A. Med12 regulates ovarian steroidogenesis, uterine development and maternal effects in the mammalian egg. Biol Reprod 2019; 97:822-834. [PMID: 29126187 DOI: 10.1093/biolre/iox143] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Accepted: 11/07/2017] [Indexed: 12/21/2022] Open
Abstract
The transcriptional factor MED12 is part of the essential mediator transcriptional complex that acts as a transcriptional coactivator in all eukaryotes. Missense gain-of-function mutations in human MED12 are associated with uterine leiomyomas, yet the role of MED12 deficiency in tumorigenesis and reproductive biology has not been fully explored. We generated a Med12 reproductive conditional knockout mouse model to evaluate its role in uterine mesenchyme, granulosa cells, and oocytes. Mice heterozygous for Med12 deficiency in granulosa cells and uterus (Med12fl/+ Amhr2-Cre) were subfertile, while mice homozygous for Med12 deficiency in granulosa cells and uterus (Med12fl/fl Amhr2-Cre) were infertile. Morphological and histological analysis of the Med12fl/fl Amhr2-Cre reproductive tract revealed atrophic uteri and hyperchromatic granulosa cells with disrupted expression of Lhcgr, Esr1, and Esr2. Med12fl/fl Amhr2-Cre mice estrous cycle was disrupted, and serum analysis showed blunted rise in estradiol in response to pregnant mare serum gonadotropin. Uterine atrophy was partially rescued by exogenous steroid supplementation with dysregulation of Notch1 and Smo expression in steroid supplemented Med12fl/fl Amhr2-Cre uteri, indicating intrinsic uterine defects. Oocyte-specific ablation of Med12 caused infertility without disrupting normal folliculogenesis and ovulation, consistent with maternal effects of Med12 in early embryo development. These results show the critical importance of Med12 in reproductive tract development and that Med12 loss of function does not cause tumorigenesis in reproductive tissues.
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Affiliation(s)
- Xinye Wang
- Tsinghua MD Program, Tsinghua University School of Medicine, Beijing, China.,Department of Obstetrics, Gynecology and Reproductive Sciences, Magee-Womens Research Institute, Pittsburgh, Pennsylvania, USA
| | - Priya Mittal
- Department of Human Genetics, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.,Department of Oncology, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - Carlos A Castro
- Department of Obstetrics, Gynecology and Reproductive Sciences, Magee-Womens Research Institute, Pittsburgh, Pennsylvania, USA
| | - Gabriel Rajkovic
- Department of Obstetrics, Gynecology and Reproductive Sciences, Magee-Womens Research Institute, Pittsburgh, Pennsylvania, USA
| | - Aleksandar Rajkovic
- Department of Obstetrics, Gynecology and Reproductive Sciences, Magee-Womens Research Institute, Pittsburgh, Pennsylvania, USA.,Department of Human Genetics, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.,Department of Pathology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
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31
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Extensive cellular heterogeneity of X inactivation revealed by single-cell allele-specific expression in human fibroblasts. Proc Natl Acad Sci U S A 2018; 115:13015-13020. [PMID: 30510006 DOI: 10.1073/pnas.1806811115] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
X-chromosome inactivation (XCI) provides a dosage compensation mechanism where, in each female cell, one of the two X chromosomes is randomly silenced. However, some genes on the inactive X chromosome and outside the pseudoautosomal regions escape from XCI and are expressed from both alleles (escapees). We investigated XCI at single-cell resolution combining deep single-cell RNA sequencing with whole-genome sequencing to examine allelic-specific expression in 935 primary fibroblast and 48 lymphoblastoid single cells from five female individuals. In this framework we integrated an original method to identify and exclude doublets of cells. In fibroblast cells, we have identified 55 genes as escapees including five undescribed escapee genes. Moreover, we observed that all genes exhibit a variable propensity to escape XCI in each cell and cell type and that each cell displays a distinct expression profile of the escapee genes. A metric, the Inactivation Score-defined as the mean of the allelic expression profiles of the escapees per cell-enables us to discover a heterogeneous and continuous degree of cellular XCI with extremes represented by "inactive" cells, i.e., cells exclusively expressing the escaping genes from the active X chromosome and "escaping" cells expressing the escapees from both alleles. We found that this effect is associated with cell-cycle phases and, independently, with the XIST expression level, which is higher in the quiescent phase (G0). Single-cell allele-specific expression is a powerful tool to identify novel escapees in different tissues and provide evidence of an unexpected cellular heterogeneity of XCI.
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32
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Okamoto I. Combined Immunofluorescence, RNA FISH, and DNA FISH in Preimplantation Mouse Embryos. Methods Mol Biol 2018; 1861:149-159. [PMID: 30218366 DOI: 10.1007/978-1-4939-8766-5_12] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/17/2023]
Abstract
Transcriptional and epigenetic dynamics of the genome occur during early development in mammals. It has been difficult to study these dynamics due to the limitation of materials and the difficulty of handling. In this chapter, we describe our attempt to apply a combination of immunofluorescence (IF), and RNA and DNA fluorescent in situ hybridization (FISH) in preimplantation mouse embryos. We have concentrated on refining these techniques to study the dynamics of X chromosome inactivation in mouse embryos. The techniques and general underlying principles described here should be applicable to other mammals of interest.
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Affiliation(s)
- Ikuhiro Okamoto
- Department of Anatomy and Cell Biology, Graduate School of Medicine, Kyoto University, Kyoto, Japan. .,JST, ERATO, Kyoto, Japan.
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33
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Cantone I, Fisher AG. Human X chromosome inactivation and reactivation: implications for cell reprogramming and disease. Philos Trans R Soc Lond B Biol Sci 2018; 372:rstb.2016.0358. [PMID: 28947657 DOI: 10.1098/rstb.2016.0358] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/15/2017] [Indexed: 11/12/2022] Open
Abstract
X-chromosome inactivation (XCI) is an exemplar of epigenetic regulation that is set up as pluripotent cells differentiate. Once established, XCI is stably propagated, but can be reversed in vivo or by pluripotent reprogramming in vitro Although reprogramming provides a useful model for inactive X (Xi) reactivation in mouse, the relative instability and heterogeneity of human embryonic stem (ES) cells and induced pluripotent stem cells hampers comparable progress in human. Here we review studies aimed at reactivating the human Xi using different reprogramming strategies. We outline our recent results using mouse ES cells to reprogramme female human fibroblasts by cell-cell fusion. We show that pluripotent reprogramming induces widespread and rapid chromatin remodelling in which the human Xi loses XIST and H3K27m3 enrichment and selected Xi genes become reactivated, ahead of mitotic division. Using RNA sequencing to map the extent of human Xi reactivation, and chromatin-modifying drugs to potentiate reactivation, we outline how this approach could be used to better design strategies to re-express human X-linked loci. As cell fusion induces the expression of human pluripotency genes that represent both the 'primed' and 'naive' states, this approach may also offer a fresh opportunity to segregate human pluripotent states with distinct Xi expression profiles, using single-cell-based approaches.This article is part of the themed issue 'X-chromosome inactivation: a tribute to Mary Lyon'.
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Affiliation(s)
- Irene Cantone
- Lymphocyte Development, MRC London Institute of Medical Sciences (LMS), Du Cane Road, London W12 0NN, UK
| | - Amanda G Fisher
- Lymphocyte Development, MRC London Institute of Medical Sciences (LMS), Du Cane Road, London W12 0NN, UK .,Institute of Clinical Sciences (ICS), Faculty of Medicine, Imperial College London, Du Cane Road, London W12 0NN, UK
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34
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Studying X chromosome inactivation in the single-cell genomic era. Biochem Soc Trans 2018; 46:577-586. [PMID: 29678955 DOI: 10.1042/bst20170346] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Revised: 03/23/2018] [Accepted: 03/26/2018] [Indexed: 01/03/2023]
Abstract
Single-cell genomics is set to revolutionise our understanding of how epigenetic silencing works; by studying specific epigenetic marks or chromatin conformations in single cells, it is possible to ask whether they cause transcriptional silencing or are instead a consequence of the silent state. Here, we review what single-cell genomics has revealed about X chromosome inactivation, perhaps the best characterised mammalian epigenetic process, highlighting the novel findings and important differences between mouse and human X inactivation uncovered through these studies. We consider what fundamental questions these techniques are set to answer in coming years and propose that X chromosome inactivation is an ideal model to study gene silencing by single-cell genomics as technical limitations are minimised through the co-analysis of hundreds of genes.
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35
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Impact of Xist RNA on chromatin modifications and transcriptional silencing maintenance at different stages of imprinted X chromosome inactivation in vole Microtus levis. Chromosoma 2017; 127:129-139. [PMID: 29151149 DOI: 10.1007/s00412-017-0650-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Revised: 10/19/2017] [Accepted: 10/30/2017] [Indexed: 10/18/2022]
Abstract
In vole Microtus levis, cells of preimplantation embryo and extraembryonic tissues undergo imprinted X chromosome inactivation (iXCI) which is triggered by a long non-coding nuclear RNA, Xist. At early stages of iXCI, chromatin of vole inactive X chromosome is enriched with the HP1 heterochromatin-specific protein, trimethylated H3K9 and H4K20 attributable to constitutive heterochromatin. In the study, using vole trophoblast stem (TS) cells as a model of iXCI, we further investigated chromatin of the inactive X chromosome of M. levis and tried to find out the role of Xist RNA. We demonstrated that chromatin of the inactive X chromosome in vole TS cells also contained the SETDB1 histone methyltransferase and KAP1 protein. In addition, we observed that Xist RNA did not contribute significantly to maintenance of X chromosome inactive state during iXCI in vole TS cells. Xist repression affected neither transcriptional silencing caused by iXCI nor maintenance of trimethylated H3K9 and H4K20 as well as HP1, KAP1, and SETDB1 on the inactive X chromosome. Moreover, the unique repertoire of chromatin modifications on the inactive X chromosome in vole TS cells could be disrupted by a chemical compound, DZNep, and then restored even in the absence of Xist RNA. However, Xist transcript was necessary for recruitment of an additional repressive histone modification, trimethylated H3K27, to the inactive X chromosome during vole TS cell differentiation.
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36
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Carrel L, Brown CJ. When the Lyon(ized chromosome) roars: ongoing expression from an inactive X chromosome. Philos Trans R Soc Lond B Biol Sci 2017; 372:20160355. [PMID: 28947654 PMCID: PMC5627157 DOI: 10.1098/rstb.2016.0355] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/24/2017] [Indexed: 12/21/2022] Open
Abstract
A tribute to Mary Lyon was held in October 2016. Many remarked about Lyon's foresight regarding many intricacies of the X-chromosome inactivation process. One such example is that a year after her original 1961 hypothesis she proposed that genes with Y homologues should escape from X inactivation to achieve dosage compensation between males and females. Fifty-five years later we have learned many details about these escapees that we attempt to summarize in this review, with a particular focus on recent findings. We now know that escapees are not rare, particularly on the human X, and that most lack functionally equivalent Y homologues, leading to their increasingly recognized role in sexually dimorphic traits. Newer sequencing technologies have expanded profiling of primary tissues that will better enable connections to sex-biased disorders as well as provide additional insights into the X-inactivation process. Chromosome organization, nuclear location and chromatin environments distinguish escapees from other X-inactivated genes. Nevertheless, several big questions remain, including what dictates their distinct epigenetic environment, the underlying basis of species differences in escapee regulation, how different classes of escapees are distinguished, and the roles that local sequences and chromosome ultrastructure play in escapee regulation.This article is part of the themed issue 'X-chromosome inactivation: a tribute to Mary Lyon'.
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Affiliation(s)
- Laura Carrel
- Department of Biochemistry and Molecular Biology, Penn State College of Medicine, 500 University Drive, Mail code H171, Hershey, PA 17033, USA
| | - Carolyn J Brown
- Department of Medical Genetics, Molecular Epigenetics Group, Life Sciences Institute, University of British Columbia, 2350 Health Sciences Mall, Vancouver, Canada BC V6T 1Z3
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37
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Contribution of epigenetic landscapes and transcription factors to X-chromosome reactivation in the inner cell mass. Nat Commun 2017; 8:1297. [PMID: 29101321 PMCID: PMC5670228 DOI: 10.1038/s41467-017-01415-5] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Accepted: 09/15/2017] [Indexed: 12/11/2022] Open
Abstract
X-chromosome inactivation is established during early development. In mice, transcriptional repression of the paternal X-chromosome (Xp) and enrichment in epigenetic marks such as H3K27me3 is achieved by the early blastocyst stage. X-chromosome inactivation is then reversed in the inner cell mass. The mechanisms underlying Xp reactivation remain enigmatic. Using in vivo single-cell approaches (allele-specific RNAseq, nascent RNA-fluorescent in situ hybridization and immunofluorescence), we show here that different genes are reactivated at different stages, with more slowly reactivated genes tending to be enriched in H3meK27. We further show that in UTX H3K27 histone demethylase mutant embryos, these genes are even more slowly reactivated, suggesting that these genes carry an epigenetic memory that may be actively lost. On the other hand, expression of rapidly reactivated genes may be driven by transcription factors. Thus, some X-linked genes have minimal epigenetic memory in the inner cell mass, whereas others may require active erasure of chromatin marks. X-chromosome inactivation is reversed in the mouse inner cell mass (ICM) through a mechanism that is not fully understood. Here, the authors investigate this process and characterize the contributions of the epigenetic landscape and transcription factors in X-linked gene reactivation dynamics.
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38
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Yue M, Ogawa A, Yamada N, Charles Richard JL, Barski A, Ogawa Y. Xist RNA repeat E is essential for ASH2L recruitment to the inactive X and regulates histone modifications and escape gene expression. PLoS Genet 2017; 13:e1006890. [PMID: 28686623 PMCID: PMC5521851 DOI: 10.1371/journal.pgen.1006890] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Revised: 07/21/2017] [Accepted: 06/22/2017] [Indexed: 12/21/2022] Open
Abstract
Long non-coding RNA Xist plays a crucial role in establishing and maintaining X-chromosome inactivation (XCI) which is a paradigm of long non-coding RNA-mediated gene regulation. Xist has Xist-specific repeat elements A-F which are conserved among eutherian mammals, underscoring their functional importance. Here we report that Xist RNA repeat E, a conserved Xist repeat element in the Xist exon 7, interacts with ASH2L and contributes to maintenance of escape gene expression level on the inactive X-chromosome (Xi) during XCI. The Xist repeat E-deletion mutant female ES cells show the depletion of ASH2L from the Xi upon differentiation. Furthermore, a subset of escape genes exhibits unexpectedly higher expression in the repeat E mutant cells than the cells expressing wildtype Xist during X-inactivation, whereas the silencing of X-linked non-escape genes is not affected. We discuss the implications of these results to understand the role of ASH2L and Xist repeat E for histone modifications and escape gene regulation during random X-chromosome inactivation.
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Affiliation(s)
- Minghui Yue
- Division of Reproductive Sciences, Perinatal Institute, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio, United States of America
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America
| | - Akiyo Ogawa
- Division of Reproductive Sciences, Perinatal Institute, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio, United States of America
| | - Norishige Yamada
- Division of Reproductive Sciences, Perinatal Institute, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio, United States of America
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America
| | - John Lalith Charles Richard
- Division of Reproductive Sciences, Perinatal Institute, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio, United States of America
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America
| | - Artem Barski
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America
- Division of Allergy & Immunology and Human Genetics, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio, United States of America
| | - Yuya Ogawa
- Division of Reproductive Sciences, Perinatal Institute, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio, United States of America
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America
- * E-mail:
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39
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Sakata Y, Nagao K, Hoki Y, Sasaki H, Obuse C, Sado T. Defects in dosage compensation impact global gene regulation in the mouse trophoblast. Development 2017; 144:2784-2797. [PMID: 28684628 DOI: 10.1242/dev.149138] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Accepted: 06/27/2017] [Indexed: 12/11/2022]
Abstract
Xist RNA, which is responsible for X inactivation, is a key epigenetic player in the embryogenesis of female mammals. Of the several repeats conserved in Xist RNA, the A-repeat has been shown to be essential for its silencing function in differentiating embryonic stem cells. Here, we introduced a new Xist allele into mouse that produces mutated Xist RNA lacking the A-repeat (XistCAGΔ5' ). XistCAGΔ5' RNA expressed in the embryo coated the X chromosome but failed to silence it. Although imprinted X inactivation was substantially compromised upon paternal transmission, allele-specific RNA-seq in the trophoblast revealed that XistCAGΔ5' RNA still retained some silencing ability. Furthermore, the failure of imprinted X inactivation had more significant impacts than expected on genome-wide gene expression. It is likely that dosage compensation is required not only for equalizing X-linked gene expression between the sexes but also for proper global gene regulation in differentiated female somatic cells.
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Affiliation(s)
- Yuka Sakata
- Department of Bioscience, Graduate School of Agriculture, Kindai University, 3327-204, Nakamachi, Nara 631-8505, Japan.,Division of Epigenomics, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Koji Nagao
- Graduate School of Life Science, Hokkaido University, Sapporo, Hokkaido 001-0021, Japan.,Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - Yuko Hoki
- Division of Epigenomics, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Hiroyuki Sasaki
- Division of Epigenomics, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Chikashi Obuse
- Graduate School of Life Science, Hokkaido University, Sapporo, Hokkaido 001-0021, Japan.,Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - Takashi Sado
- Department of Bioscience, Graduate School of Agriculture, Kindai University, 3327-204, Nakamachi, Nara 631-8505, Japan .,Division of Epigenomics, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
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40
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Min B, Park JS, Jeon K, Kang YK. Characterization of X-Chromosome Gene Expression in Bovine Blastocysts Derived by In vitro Fertilization and Somatic Cell Nuclear Transfer. Front Genet 2017; 8:42. [PMID: 28443134 PMCID: PMC5385346 DOI: 10.3389/fgene.2017.00042] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2017] [Accepted: 03/24/2017] [Indexed: 12/26/2022] Open
Abstract
To better understand X-chromosome reactivation (XCR) during early development, we analyzed transcriptomic data obtained from bovine male and female blastocysts derived by in-vitro fertilization (IVF) or somatic-cell nuclear transfer (SCNT). We found that X-linked genes were upregulated by almost two-fold in female compared with male IVF blastocysts. The upregulation of X-linked genes in female IVFs indicated a transcriptional dimorphism between the sexes, because the mean autosomal gene expression levels were relatively constant, regardless of sex. X-linked genes were expressed equivalently in the inner-cell mass and the trophectoderm parts of female blastocysts, indicating no imprinted inactivation of paternal X in the trophectoderm. All these features of X-linked gene expression observed in IVFs were also detected in SCNT blastocysts, although to a lesser extent. A heatmap of X-linked gene expression revealed that the initial resemblance of X-linked gene expression patterns between male and female donor cells turned sexually divergent in host SCNTs, ultimately resembling the patterns of male and female IVFs. Additionally, we found that sham SCNT blastocysts, which underwent the same nuclear-transfer procedures, but retained their embryonic genome, closely mimicked IVFs for X-linked gene expression, which indicated that the embryo manipulation procedure itself does not interfere with XCR in SCNT blastocysts. Our findings indicated that female SCNTs have less efficient XCR, suggesting that clonal reprogramming of X chromosomes is incomplete and occurs variably among blastocysts, and even among cells in a single blastocyst.
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Affiliation(s)
- Byungkuk Min
- Development and Differentiation Research Center, Korea Research Institute of Bioscience BiotechnologyDaejeon, South Korea
| | - Jung Sun Park
- Development and Differentiation Research Center, Korea Research Institute of Bioscience BiotechnologyDaejeon, South Korea
| | - Kyuheum Jeon
- Development and Differentiation Research Center, Korea Research Institute of Bioscience BiotechnologyDaejeon, South Korea
| | - Yong-Kook Kang
- Development and Differentiation Research Center, Korea Research Institute of Bioscience BiotechnologyDaejeon, South Korea
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41
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Abstract
X chromosome inactivation (XCI) is a dosage compensation process that was adopted by female mammals to balance gene dosage between XX females and XY males. XCI starts with the upregulation of the non-coding RNA Xist, after which most X-linked genes are silenced and acquire a repressive chromatin state. Even though the chromatin marks of the inactive X have been fairly well described, the mechanisms responsible for the initiation of XCI remain largely unknown. In this review, we discuss recent developments that revealed unexpected factors playing a role in XCI and that might be of crucial importance to understand the mechanisms responsible for the very first steps of this chromosome-wide gene-silencing event.
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Affiliation(s)
- Ines Pinheiro
- Mammalian Developmental Epigenetics Group (équipe labellisée La Ligue), Institut Curie, PSL Research University, CNRS UMR3215, INSERM U934, 26 Rue d'Ulm, 11 75248 Paris Cedex 05, France
| | - Edith Heard
- Mammalian Developmental Epigenetics Group (équipe labellisée La Ligue), Institut Curie, PSL Research University, CNRS UMR3215, INSERM U934, 26 Rue d'Ulm, 11 75248 Paris Cedex 05, France
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42
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Xist-dependent imprinted X inactivation and the early developmental consequences of its failure. Nat Struct Mol Biol 2017; 24:226-233. [PMID: 28134930 DOI: 10.1038/nsmb.3365] [Citation(s) in RCA: 92] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2016] [Accepted: 12/20/2016] [Indexed: 12/18/2022]
Abstract
The long noncoding RNA Xist is expressed from only the paternal X chromosome in mouse preimplantation female embryos and mediates transcriptional silencing of that chromosome. In females, absence of Xist leads to postimplantation lethality. Here, through single-cell RNA sequencing of early preimplantation mouse embryos, we found that the initiation of imprinted X-chromosome inactivation absolutely requires Xist. Lack of paternal Xist leads to genome-wide transcriptional misregulation in the early blastocyst and to failure to activate the extraembryonic pathway that is essential for postimplantation development. We also demonstrate that the expression dynamics of X-linked genes depends on the strain and parent of origin as well as on the location along the X chromosome, particularly at the first 'entry' sites of Xist. This study demonstrates that dosage-compensation failure has an effect as early as the blastocyst stage and reveals genetic and epigenetic contributions to orchestrating transcriptional silencing of the X chromosome during early embryogenesis.
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43
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Cantone I, Dharmalingam G, Chan YW, Kohler AC, Lenhard B, Merkenschlager M, Fisher AG. Allele-specific analysis of cell fusion-mediated pluripotent reprograming reveals distinct and predictive susceptibilities of human X-linked genes to reactivation. Genome Biol 2017; 18:2. [PMID: 28118853 PMCID: PMC5264468 DOI: 10.1186/s13059-016-1136-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Accepted: 12/14/2016] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Inactivation of one X chromosome is established early in female mammalian development and can be reversed in vivo and in vitro when pluripotency factors are re-expressed. The extent of reactivation along the inactive X chromosome (Xi) and the determinants of locus susceptibility are, however, poorly understood. Here we use cell fusion-mediated pluripotent reprograming to study human Xi reactivation and allele-specific single nucleotide polymorphisms (SNPs) to identify reactivated loci. RESULTS We show that a subset of human Xi genes is rapidly reactivated upon re-expression of the pluripotency network. These genes lie within the most evolutionary recent segments of the human X chromosome that are depleted of LINE1 and enriched for SINE elements, predicted to impair XIST spreading. Interestingly, this cadre of genes displays stochastic Xi expression in human fibroblasts ahead of reprograming. This stochastic variability is evident between clones, by RNA-sequencing, and at the single-cell level, by RNA-FISH, and is not attributable to differences in repressive histone H3K9me3 or H3K27me3 levels. Treatment with the DNA demethylating agent 5-deoxy-azacytidine does not increase Xi expression ahead of reprograming, but instead reveals a second cadre of genes that only become susceptible to reactivation upon induction of pluripotency. CONCLUSIONS Collectively, these data not only underscore the multiple pathways that contribute to maintaining silencing along the human Xi chromosome but also suggest that transcriptional stochasticity among human cells could be useful for predicting and engineering epigenetic strategies to achieve locus-specific or domain-specific human Xi gene reactivation.
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Affiliation(s)
- Irene Cantone
- Lymphocyte Development Group, MRC London Institute of Medical Sciences, Hammersmith Campus, Imperial College London, Du Cane Road, London, W12 0NN, UK.
| | - Gopuraja Dharmalingam
- Bioinformatics and Computing facility, MRC London Institute of Medical Sciences, Imperial College, London, UK
| | - Yi-Wah Chan
- Lymphocyte Development Group, MRC London Institute of Medical Sciences, Hammersmith Campus, Imperial College London, Du Cane Road, London, W12 0NN, UK
| | - Anne-Celine Kohler
- Lymphocyte Development Group, MRC London Institute of Medical Sciences, Hammersmith Campus, Imperial College London, Du Cane Road, London, W12 0NN, UK
| | - Boris Lenhard
- Computational Regulatory Genomics Group, MRC London Institute of Medical Sciences, Imperial College, London, UK
| | - Matthias Merkenschlager
- Lymphocyte Development Group, MRC London Institute of Medical Sciences, Hammersmith Campus, Imperial College London, Du Cane Road, London, W12 0NN, UK
| | - Amanda G Fisher
- Lymphocyte Development Group, MRC London Institute of Medical Sciences, Hammersmith Campus, Imperial College London, Du Cane Road, London, W12 0NN, UK.
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44
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Ranisavljevic N, Okamoto I, Heard E, Ancelin K. RNA FISH to Study Zygotic Genome Activation in Early Mouse Embryos. Methods Mol Biol 2017; 1605:133-145. [PMID: 28456962 DOI: 10.1007/978-1-4939-6988-3_9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Characterizing the maternal-to-zygotic transition (MZT) is a central question in embryogenesis, and is critical for our understanding of early post-fertilization events in mammals. High-throughput RNA sequencing (RNA Seq) of mouse oocytes and early embryos has recently revealed that elaborate transcription patterns of genes and repeats are established post-fertilization. This occurs in the context of the gradually depleted maternal pool of RNA provided by the oocyte, which can confound the accurate analysis of the zygotic genome activation when the mRNA population is sequenced. In this context, and given the limited amounts of material available from embryos, particularly when studying mutants, as well as the cost of sequencing, an alternative, complementary single cell approach is RNA FISH. This approach can assay the expression of specific genes or genetic elements during preimplantation development, in particular during the MZT. Here, we describe how RNA FISH can be applied to visualize nascent transcription at specific genomic loci in embryos at different stages of preimplantation development and also discuss possible analytical methods of RNA FISH data.
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Affiliation(s)
- Noémie Ranisavljevic
- Unité de Génétique et Biologie du Développement, Institut Curie, PSL Research University, CNRS UMR 3215, INSERM U934, 26 rue d'Ulm, 75248 Paris Cedex 05, France
| | - Ikuhiro Okamoto
- Department of Anatomy and Cell Biology, Graduate School of Medicine, Kyoto university, yoshida-konoe-cho, saikyo-ku, Kyoto 606-0581, Japan
| | - Edith Heard
- Unité de Génétique et Biologie du Développement, Institut Curie, PSL Research University, CNRS UMR 3215, INSERM U934, 26 rue d'Ulm, 75248 Paris Cedex 05, France
| | - Katia Ancelin
- Unité de Génétique et Biologie du Développement, Institut Curie, PSL Research University, CNRS UMR 3215, INSERM U934, 26 rue d'Ulm, 75248 Paris Cedex 05, France.
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45
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Dupont C, Maduro C, Den Braanker H, Boers R, Kurek D, Gribnau J. Characterization of Histone Modifications Associated with Inactive X-Chromosome in Trophoblast Stem Cells, eXtra-Embryonic Endoderm Cells and in In Vitro Derived Undifferentiated and Differentiated Epiblast Like Stem Cells. PLoS One 2016; 11:e0167154. [PMID: 27977710 PMCID: PMC5157996 DOI: 10.1371/journal.pone.0167154] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Accepted: 11/09/2016] [Indexed: 11/30/2022] Open
Abstract
In mouse, X-chromosome inactivation (XCI) can either be imprinted or random. Imprinted XCI (iXCI) is considered unstable and depending on continuous Xist expression, whereas random XCI (rXCI) is stably maintained even in the absence of Xist. Here we have systematically examined epigenetic modifications associated with the inactive X-chromosome (Xi) in Trophoblast Stem cells, eXtra-Embryonic Endoderm Cells, undifferentiated and differentiated Epiblast Like Stem Cells in order to understand intrinsic differences in epigenetic mechanisms involved in silencing of the inactive X-chromosome in lineages presenting iXCI and rXCI. Whereas euchromatic histone modifications are predominantly lost from the Xi territory in all cell types, the accumulation of heterochromatic modifications diverges in between the analysed cell lineages. Particularly, only the Xi of multipotent Trophoblast (iXCI) and Epiblast stem cells (rXCI) display a visible accumulation of Polycomb Repressive Complexes (PRCs), in contrast to the Xi in differentiated Epiblast Like Stem Cells and eXtra-embryonic Endoderm cells. Despite this, the histone modifications catalysed by PRCs, ubH2AK119 and H3K27me3, remain the best heterochromatic markers for the Xi in all assessed lineages. Heterochromatic chromatin modifications associated with the Xi are a reflection of the epigenetic landscape of the entire genome of the assessed cell regardless whether XCI is imprinted or random.
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Affiliation(s)
- Cathérine Dupont
- Erasmus MC, Department of Developmental Biology, Rotterdam, The Netherlands
| | - Cheryl Maduro
- Erasmus MC, Department of Developmental Biology, Rotterdam, The Netherlands
| | | | - Ruben Boers
- Erasmus MC, Department of Developmental Biology, Rotterdam, The Netherlands
| | - Dorota Kurek
- Erasmus MC, Department of Developmental Biology, Rotterdam, The Netherlands
| | - Joost Gribnau
- Erasmus MC, Department of Developmental Biology, Rotterdam, The Netherlands
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46
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Dunford A, Weinstock DM, Savova V, Schumacher SE, Cleary JP, Yoda A, Sullivan TJ, Hess JM, Gimelbrant AA, Beroukhim R, Lawrence MS, Getz G, Lane AA. Tumor-suppressor genes that escape from X-inactivation contribute to cancer sex bias. Nat Genet 2016; 49:10-16. [PMID: 27869828 PMCID: PMC5206905 DOI: 10.1038/ng.3726] [Citation(s) in RCA: 261] [Impact Index Per Article: 32.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Accepted: 10/24/2016] [Indexed: 12/14/2022]
Abstract
There is a striking and unexplained male predominance across many cancer types. A subset of X-chromosome genes can escape X-inactivation, which would protect females from complete functional loss by a single mutation. To identify putative 'escape from X-inactivation tumor-suppressor' (EXITS) genes, we examined somatic alterations from >4,100 cancers across 21 tumor types for sex bias. Six of 783 non-pseudoautosomal region (PAR) X-chromosome genes (ATRX, CNKSR2, DDX3X, KDM5C, KDM6A, and MAGEC3) harbored loss-of-function mutations more frequently in males (based on a false discovery rate < 0.1), in comparison to zero of 18,055 autosomal and PAR genes (Fisher's exact P < 0.0001). Male-biased mutations in genes that escape X-inactivation were observed in combined analysis across many cancers and in several individual tumor types, suggesting a generalized phenomenon. We conclude that biallelic expression of EXITS genes in females explains a portion of the reduced cancer incidence in females as compared to males across a variety of tumor types.
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Affiliation(s)
- Andrew Dunford
- Broad Institute of Harvard and MIT, Cambridge, Massachusetts, USA
| | - David M Weinstock
- Broad Institute of Harvard and MIT, Cambridge, Massachusetts, USA.,Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts, USA
| | - Virginia Savova
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA.,Department of Genetics, Harvard Medical School, Boston, Massachusetts, USA
| | - Steven E Schumacher
- Broad Institute of Harvard and MIT, Cambridge, Massachusetts, USA.,Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA
| | - John P Cleary
- Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts, USA
| | - Akinori Yoda
- Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts, USA
| | | | - Julian M Hess
- Broad Institute of Harvard and MIT, Cambridge, Massachusetts, USA
| | - Alexander A Gimelbrant
- Broad Institute of Harvard and MIT, Cambridge, Massachusetts, USA.,Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA.,Department of Genetics, Harvard Medical School, Boston, Massachusetts, USA
| | - Rameen Beroukhim
- Broad Institute of Harvard and MIT, Cambridge, Massachusetts, USA.,Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts, USA.,Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA
| | - Michael S Lawrence
- Department of Pathology and Cancer Center, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Gad Getz
- Broad Institute of Harvard and MIT, Cambridge, Massachusetts, USA.,Department of Pathology and Cancer Center, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Andrew A Lane
- Broad Institute of Harvard and MIT, Cambridge, Massachusetts, USA.,Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts, USA
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47
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Wang F, Shin J, Shea JM, Yu J, Bošković A, Byron M, Zhu X, Shalek AK, Regev A, Lawrence JB, Torres EM, Zhu LJ, Rando OJ, Bach I. Regulation of X-linked gene expression during early mouse development by Rlim. eLife 2016; 5. [PMID: 27642011 PMCID: PMC5059138 DOI: 10.7554/elife.19127] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2016] [Accepted: 09/15/2016] [Indexed: 01/22/2023] Open
Abstract
Mammalian X-linked gene expression is highly regulated as female cells contain two and male one X chromosome (X). To adjust the X gene dosage between genders, female mouse preimplantation embryos undergo an imprinted form of X chromosome inactivation (iXCI) that requires both Rlim (also known as Rnf12) and the long non-coding RNA Xist. Moreover, it is thought that gene expression from the single active X is upregulated to correct for bi-allelic autosomal (A) gene expression. We have combined mouse genetics with RNA-seq on single mouse embryos to investigate functions of Rlim on the temporal regulation of iXCI and Xist. Our results reveal crucial roles of Rlim for the maintenance of high Xist RNA levels, Xist clouds and X-silencing in female embryos at blastocyst stages, while initial Xist expression appears Rlim-independent. We find further that X/A upregulation is initiated in early male and female preimplantation embryos. DOI:http://dx.doi.org/10.7554/eLife.19127.001
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Affiliation(s)
- Feng Wang
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, Worcester, United States
| | - JongDae Shin
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, Worcester, United States.,Department of Cell Biology, College of Medicine, Konyang University, Daejeon, Korea
| | - Jeremy M Shea
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, United States
| | - Jun Yu
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, Worcester, United States
| | - Ana Bošković
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, United States
| | - Meg Byron
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, United States
| | - Xiaochun Zhu
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, Worcester, United States
| | - Alex K Shalek
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, United States.,Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, United States.,Broad Institute of MIT and Harvard, Cambridge, United States.,Ragon Institute of MGH, MIT and Harvard, Cambridge, United States
| | - Aviv Regev
- Broad Institute of MIT and Harvard, Cambridge, United States.,Department of Biology, Massachusetts Institute of Technology, Cambridge, United States.,Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, United States
| | - Jeanne B Lawrence
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, United States
| | - Eduardo M Torres
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, Worcester, United States
| | - Lihua J Zhu
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, Worcester, United States.,Program in Bioinformatics and Integrative Biology, University of Massachusetts Medical School, Worcester, United States
| | - Oliver J Rando
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, United States
| | - Ingolf Bach
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, Worcester, United States
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48
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Corbel C, Heard E. Transcriptional Analysis by Nascent RNA FISH of In Vivo Trophoblast Giant Cells or In Vitro Short-term Cultures of Ectoplacental Cone Explants. J Vis Exp 2016:54386. [PMID: 27685354 PMCID: PMC5091979 DOI: 10.3791/54386] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The placenta derives from one extra-embryonic lineage, the trophectoderm. In the peri-implantation murine blastocyst, mural trophectoderm cells differentiate into primary trophoblast giant cells (TGCs) while the polar trophectoderm overlying the inner cell mass continues to proliferate later differentiating into secondary TGCs. TGCs play a key role in developing placenta and are essential for a successful pregnancy. Investigation of transcriptional regulation of specific genes during post-implantation development can give insights into TGCs development. Cells of the ectoplacental cone (EPC) from embryos at 7-7.5 days of gestation (E7-7.5), derived from the polar trophectoderm, differentiate into secondary TGCs1. TGCs can be studied in situ, on cryostat sections of embryos at E7 although the number of TGCs is very low at this stage. An alternative means of analyzing secondary TGCs is to use short-term cultures of individual EPCs from E7 embryos. We propose a technique to investigate the transcriptional status of genes of interest both in vivo and in vitro at the single-cell level using fluorescent in situ hybridization (RNA FISH) to visualize nascent transcripts. This technique provides a direct readout of gene expression and enables assessment of the chromosomal status of TGCs, which are large endoreplicating cells. Indeed, a key feature of terminal differentiation of TGCs is that they exit the cell cycle and undergo multiple rounds of endoreplication.This approach can be applied to detect expression of any gene expressed from autosomes and/or sex chromosomes and can provide important information into developmental mechanisms as well as placental diseases.
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Affiliation(s)
- Catherine Corbel
- Unité de Génétique et Biologie du Développement, Institut Curie, PSL Research University, CNRS UMR 3215, INSERM U934;
| | - Edith Heard
- Unité de Génétique et Biologie du Développement, Institut Curie, PSL Research University, CNRS UMR 3215, INSERM U934
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49
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Giorgetti L, Lajoie BR, Carter AC, Attia M, Zhan Y, Xu J, Chen CJ, Kaplan N, Chang HY, Heard E, Dekker J. Structural organization of the inactive X chromosome in the mouse. Nature 2016; 535:575-9. [PMID: 27437574 PMCID: PMC5443622 DOI: 10.1038/nature18589] [Citation(s) in RCA: 269] [Impact Index Per Article: 33.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Accepted: 05/18/2016] [Indexed: 12/23/2022]
Abstract
X-chromosome inactivation (XCI) involves major reorganization of the X chromosome as it becomes silent and heterochromatic. During female mammalian development, XCI is triggered by upregulation of the non-coding Xist RNA from one of the two X chromosomes. Xist coats the chromosome in cis and induces silencing of almost all genes via its A-repeat region, although some genes (constitutive escapees) avoid silencing in most cell types, and others (facultative escapees) escape XCI only in specific contexts. A role for Xist in organizing the inactive X (Xi) chromosome has been proposed. Recent chromosome conformation capture approaches have revealed global loss of local structure on the Xi chromosome and formation of large mega-domains, separated by a region containing the DXZ4 macrosatellite. However, the molecular architecture of the Xi chromosome, in both the silent and expressed regions,remains unclear. Here we investigate the structure, chromatin accessibility and expression status of the mouse Xi chromosome in highly polymorphic clonal neural progenitors (NPCs) and embryonic stem cells. We demonstrate a crucial role for Xist and the DXZ4-containing boundary in shaping Xi chromosome structure using allele-specific genome-wide chromosome conformation capture (Hi-C) analysis, an assay for transposase-accessible chromatin with high throughput sequencing (ATAC-seq) and RNA sequencing. Deletion of the boundary disrupts mega-domain formation, and induction of Xist RNA initiates formation of the boundary and the loss of DNA accessibility. We also show that in NPCs, the Xi chromosome lacks active/inactive compartments and topologically associating domains (TADs), except around genes that escape XCI. Escapee gene clusters display TAD-like structures and retain DNA accessibility at promoter-proximal and CTCF-binding sites. Furthermore, altered patterns of facultative escape genes indifferent neural progenitor clones are associated with the presence of different TAD-like structures after XCI. These findings suggest a key role for transcription and CTCF in the formation of TADs in the context of the Xi chromosome in neural progenitors.
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50
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Kobayashi S, Hosoi Y, Shiura H, Yamagata K, Takahashi S, Fujihara Y, Kohda T, Okabe M, Ishino F. Live imaging of X chromosome reactivation dynamics in early mouse development can discriminate naïve from primed pluripotent stem cells. Development 2016; 143:2958-64. [PMID: 27471261 DOI: 10.1242/dev.136739] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Accepted: 07/08/2016] [Indexed: 02/04/2023]
Abstract
Pluripotent stem cells can be classified into two distinct states, naïve and primed, which show different degrees of potency. One difficulty in stem cell research is the inability to distinguish these states in live cells. Studies on female mice have shown that reactivation of inactive X chromosomes occurs in the naïve state, while one of the X chromosomes is inactivated in the primed state. Therefore, we aimed to distinguish the two states by monitoring X chromosome reactivation. Thus far, X chromosome reactivation has been analysed using fixed cells; here, we inserted different fluorescent reporter gene cassettes (mCherry and eGFP) into each X chromosome. Using these knock-in 'Momiji' mice, we detected X chromosome reactivation accurately in live embryos, and confirmed that the pluripotent states of embryos were stable ex vivo, as represented by embryonic and epiblast stem cells in terms of X chromosome reactivation. Thus, Momiji mice provide a simple and accurate method for identifying stem cell status based on X chromosome reactivation.
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Affiliation(s)
- Shin Kobayashi
- Department of Epigenetics, Medical Research Institute, Tokyo Medical & Dental University, 1-5-45 Yushima Bunkyo-ku, Tokyo 113-8510, Japan
| | - Yusuke Hosoi
- Department of Epigenetics, Medical Research Institute, Tokyo Medical & Dental University, 1-5-45 Yushima Bunkyo-ku, Tokyo 113-8510, Japan
| | - Hirosuke Shiura
- Department of Epigenetics, Medical Research Institute, Tokyo Medical & Dental University, 1-5-45 Yushima Bunkyo-ku, Tokyo 113-8510, Japan
| | - Kazuo Yamagata
- Research Institute for Microbial Diseases, Osaka University, Yamadaoka 3-1, Suita, Osaka 565-0871, Japan
| | - Saori Takahashi
- Department of Epigenetics, Medical Research Institute, Tokyo Medical & Dental University, 1-5-45 Yushima Bunkyo-ku, Tokyo 113-8510, Japan
| | - Yoshitaka Fujihara
- Research Institute for Microbial Diseases, Osaka University, Yamadaoka 3-1, Suita, Osaka 565-0871, Japan
| | - Takashi Kohda
- Department of Epigenetics, Medical Research Institute, Tokyo Medical & Dental University, 1-5-45 Yushima Bunkyo-ku, Tokyo 113-8510, Japan
| | - Masaru Okabe
- Research Institute for Microbial Diseases, Osaka University, Yamadaoka 3-1, Suita, Osaka 565-0871, Japan
| | - Fumitoshi Ishino
- Department of Epigenetics, Medical Research Institute, Tokyo Medical & Dental University, 1-5-45 Yushima Bunkyo-ku, Tokyo 113-8510, Japan
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