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de la Rosa S, del Mar Rigual M, Vargiu P, Ortega S, Djouder N. Endogenous retroviruses shape pluripotency specification in mouse embryos. SCIENCE ADVANCES 2024; 10:eadk9394. [PMID: 38266080 PMCID: PMC10807815 DOI: 10.1126/sciadv.adk9394] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Accepted: 12/22/2023] [Indexed: 01/26/2024]
Abstract
The smooth and precise transition from totipotency to pluripotency is a key process in embryonic development, generating pluripotent stem cells capable of forming all cell types. While endogenous retroviruses (ERVs) are essential for early development, their precise roles in this transition remains mysterious. Using cutting-edge genetic and biochemical techniques in mice, we identify MERVL-gag, a retroviral protein, as a crucial modulator of pluripotent factors OCT4 and SOX2 during lineage specification. MERVL-gag tightly operates with URI, a prefoldin protein that concurs with pluripotency bias in mouse blastomeres, and which is indeed required for totipotency-to-pluripotency transition. Accordingly, URI loss promotes a stable totipotent-like state and embryo arrest at 2C stage. Mechanistically, URI binds and shields OCT4 and SOX2 from proteasome degradation, while MERVL-gag displaces URI from pluripotent factor interaction, causing their degradation. Our findings reveal the symbiotic coevolution of ERVs with their host cells to ensure the smooth and timely progression of early embryo development.
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Affiliation(s)
- Sergio de la Rosa
- Growth Factors, Nutrients and Cancer Group, Molecular Oncology Programme, Spanish National Cancer Research Centre (CNIO), Madrid 28029, Spain
| | - María del Mar Rigual
- Growth Factors, Nutrients and Cancer Group, Molecular Oncology Programme, Spanish National Cancer Research Centre (CNIO), Madrid 28029, Spain
| | - Pierfrancesco Vargiu
- Mouse Genome Editing Core Unit, Biotechnology Programme, Spanish National Cancer Research Centre (CNIO), Madrid 28029, Spain
| | - Sagrario Ortega
- Mouse Genome Editing Core Unit, Biotechnology Programme, Spanish National Cancer Research Centre (CNIO), Madrid 28029, Spain
| | - Nabil Djouder
- Growth Factors, Nutrients and Cancer Group, Molecular Oncology Programme, Spanish National Cancer Research Centre (CNIO), Madrid 28029, Spain
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The Adenine/Thymine Deleterious Selection Model for GC Content Evolution at the Third Codon Position of the Histone Genes in Drosophila. Genes (Basel) 2021; 12:genes12050721. [PMID: 34065869 PMCID: PMC8150595 DOI: 10.3390/genes12050721] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 05/07/2021] [Accepted: 05/07/2021] [Indexed: 12/02/2022] Open
Abstract
The evolution of the GC (guanine cytosine) content at the third codon position of the histone genes (H1, H2A, H2B, H3, H4, H2AvD, H3.3A, H3.3B, and H4r) in 12 or more Drosophila species is reviewed. For explaining the evolution of the GC content at the third codon position of the genes, a model assuming selection with a deleterious effect for adenine/thymine and a size effect is presented. The applicability of the model to whole-genome genes is also discussed.
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Positioning of nucleosomes containing γ-H2AX precedes active DNA demethylation and transcription initiation. Nat Commun 2021; 12:1072. [PMID: 33594057 PMCID: PMC7886895 DOI: 10.1038/s41467-021-21227-y] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Accepted: 01/12/2021] [Indexed: 01/09/2023] Open
Abstract
In addition to nucleosomes, chromatin contains non-histone chromatin-associated proteins, of which the high-mobility group proteins are the most abundant. Chromatin-mediated regulation of transcription involves DNA methylation and histone modifications. However, the order of events and the precise function of high-mobility group proteins during transcription initiation remain unclear. Here we show that high-mobility group AT-hook 2 protein (HMGA2) induces DNA nicks at the transcription start site, which are required by the histone chaperone FACT complex to incorporate nucleosomes containing the histone variant H2A.X. Further, phosphorylation of H2A.X at S139 (γ-H2AX) is required for repair-mediated DNA demethylation and transcription activation. The relevance of these findings is demonstrated within the context of TGFB1 signaling and idiopathic pulmonary fibrosis, suggesting therapies against this lethal disease. Our data support the concept that chromatin opening during transcriptional initiation involves intermediates with DNA breaks that subsequently require DNA repair mechanisms to ensure genome integrity. The order of DNA methylation and histone modifications during transcription remained unclear. Here the authors show that HMGA2 induces DNA nicks at TGFB1-responsive genes, promoting nucleosome incorporation containing γ-H2AX, which is required for repair-mediated DNA demethylation and transcription.
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4
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Liu CF, Tang WW. Epigenetics in Cardiac Hypertrophy and Heart Failure. JACC Basic Transl Sci 2019; 4:976-993. [PMID: 31909304 PMCID: PMC6938823 DOI: 10.1016/j.jacbts.2019.05.011] [Citation(s) in RCA: 64] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Revised: 05/29/2019] [Accepted: 05/30/2019] [Indexed: 12/14/2022]
Abstract
Heart failure (HF) is a complex syndrome affecting millions of people around the world. Over the past decade, the therapeutic potential of targeting epigenetic regulators in HF has been discussed extensively. Recent advances in next-generation sequencing techniques have contributed substantial progress in our understanding of the role of DNA methylation, post-translational modifications of histones, adenosine triphosphate (ATP)-dependent chromatin conformation and remodeling, and non-coding RNAs in HF pathophysiology. In this review, we summarize epigenomic studies on human and animal models in HF.
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Key Words
- BET, bromodomain
- EZH2, Enhancer of zeste homolog 2
- HAT, histone acetyltransferase
- HDAC, histone deacetylase
- HDM, histone demethylase
- HF, heart failure
- HMT, histone methyltransferase
- PRC2, polycomb repressor complex 2
- PTMs, post-translational modifications
- TAD, topologically associating domains
- TMAO, trimethylamine N-oxide
- cardiac hypertrophy
- epigenetics
- heart failure
- lnc-RNAs, long ncRNAs
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Affiliation(s)
- Chia-Feng Liu
- Department of Cardiovascular and Metabolic Sciences, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio
| | - W.H. Wilson Tang
- Department of Cardiovascular and Metabolic Sciences, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio
- Department of Cardiovascular Medicine, Heart and Vascular Institute, Cleveland Clinic, Cleveland, Ohio
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Abstract
Following fertilization, the two specified gametes must unite to create an entirely new organism. The genome is initially transcriptionally quiescent, allowing the zygote to be reprogrammed into a totipotent state. Gradually, the genome is activated through a process known as the maternal-to-zygotic transition, which enables zygotic gene products to replace the maternal supply that initiated development. This essential transition has been broadly characterized through decades of research in several model organisms. However, we still lack a full mechanistic understanding of how genome activation is executed and how this activation relates to the reprogramming of the zygotic chromatin architecture. Recent work highlights the central role of transcriptional activators and suggests that these factors may coordinate transcriptional activation with other developmental changes.
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Wang T, Chuffart F, Bourova-Flin E, Wang J, Mi J, Rousseaux S, Khochbin S. Histone variants: critical determinants in tumour heterogeneity. Front Med 2019; 13:289-297. [PMID: 30280307 DOI: 10.1007/s11684-018-0667-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Accepted: 07/02/2018] [Indexed: 12/25/2022]
Abstract
Malignant cell transformation could be considered as a series of cell reprogramming events driven by oncogenic transcription factors and upstream signalling pathways. Chromatin plasticity and dynamics are critical determinants in the control of cell reprograming. An increase in chromatin dynamics could therefore constitute an essential step in driving oncogenesis and in generating tumour cell heterogeneity, which is indispensable for the selection of aggressive properties, including the ability of cells to disseminate and acquire resistance to treatments. Histone supply and dosage, as well as histone variants, are the best-known regulators of chromatin dynamics. By facilitating cell reprogramming, histone under-dosage and histone variants should also be crucial in cell transformation and tumour metastasis. Here we summarize and discuss our knowledge of the role of histone supply and histone variants in chromatin dynamics and their ability to enhance oncogenic cell reprogramming and tumour heterogeneity.
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Affiliation(s)
- Tao Wang
- CNRS UMR 5309, Inserm, U1209, University of Grenoble Alpes, Institute for Advanced Biosciences, 38706, Grenoble, France.,State Key Laboratory for Medical Genomics and Department of Hematology, Shanghai Institute of Hematology, Collaborative Innovation Center of Systems Biomedicine, Pôle Sino-Français des Sciences du Vivant et Genomique, Ruijin Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Florent Chuffart
- CNRS UMR 5309, Inserm, U1209, University of Grenoble Alpes, Institute for Advanced Biosciences, 38706, Grenoble, France
| | - Ekaterina Bourova-Flin
- CNRS UMR 5309, Inserm, U1209, University of Grenoble Alpes, Institute for Advanced Biosciences, 38706, Grenoble, France
| | - Jin Wang
- State Key Laboratory for Medical Genomics and Department of Hematology, Shanghai Institute of Hematology, Collaborative Innovation Center of Systems Biomedicine, Pôle Sino-Français des Sciences du Vivant et Genomique, Ruijin Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Jianqing Mi
- State Key Laboratory for Medical Genomics and Department of Hematology, Shanghai Institute of Hematology, Collaborative Innovation Center of Systems Biomedicine, Pôle Sino-Français des Sciences du Vivant et Genomique, Ruijin Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Sophie Rousseaux
- CNRS UMR 5309, Inserm, U1209, University of Grenoble Alpes, Institute for Advanced Biosciences, 38706, Grenoble, France
| | - Saadi Khochbin
- CNRS UMR 5309, Inserm, U1209, University of Grenoble Alpes, Institute for Advanced Biosciences, 38706, Grenoble, France.
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Xu Q, Xie W. Epigenome in Early Mammalian Development: Inheritance, Reprogramming and Establishment. Trends Cell Biol 2017; 28:237-253. [PMID: 29217127 DOI: 10.1016/j.tcb.2017.10.008] [Citation(s) in RCA: 137] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Revised: 10/25/2017] [Accepted: 10/27/2017] [Indexed: 01/17/2023]
Abstract
Drastic epigenetic reprogramming takes place during preimplantation development, leading to the conversion of terminally differentiated gametes to a totipotent embryo. Deficiencies in remodeling of the epigenomes can cause severe developmental defects, including embryonic lethality. However, how chromatin modifications and chromatin organization are reprogrammed upon fertilization in mammals has long remained elusive. Here, we review recent progress in understanding how the epigenome is dynamically regulated during early mammalian development. The latest studies, including many from genome-wide perspectives, have revealed unusual principles of reprogramming for histone modifications, chromatin accessibility, and 3D chromatin architecture. These advances have shed light on the regulatory network controlling the earliest development and maternal-zygotic transition.
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Affiliation(s)
- Qianhua Xu
- Center for Stem Cell Biology and Regenerative Medicine, MOE Key Laboratory of Bioinformatics, THU-PKU Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Wei Xie
- Center for Stem Cell Biology and Regenerative Medicine, MOE Key Laboratory of Bioinformatics, THU-PKU Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China.
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Valenzuela N, Soibam B, Li L, Wang J, Byers LA, Liu Y, Schwartz RJ, Stewart MD. HIRA deficiency in muscle fibers causes hypertrophy and susceptibility to oxidative stress. J Cell Sci 2017; 130:2551-2563. [PMID: 28600325 DOI: 10.1242/jcs.200642] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2016] [Accepted: 06/05/2017] [Indexed: 01/14/2023] Open
Abstract
Nucleosome assembly proceeds through DNA replication-coupled or replication-independent mechanisms. For skeletal myocytes, whose nuclei have permanently exited the cell cycle, replication-independent assembly is the only mode available for chromatin remodeling. For this reason, any nucleosome composition alterations accompanying transcriptional responses to physiological signals must occur through a DNA replication-independent pathway. HIRA is the histone chaperone primarily responsible for replication-independent incorporation of histone variant H3.3 across gene bodies and regulatory regions. Thus, HIRA would be expected to play an important role in epigenetically regulating myocyte gene expression. The objective of this study was to determine the consequence of eliminating HIRA from mouse skeletal myocytes. At 6 weeks of age, myofibers lacking HIRA showed no pathological abnormalities; however, genes involved in transcriptional regulation were downregulated. By 6 months of age, myofibers lacking HIRA exhibited hypertrophy, sarcolemmal perforation and oxidative damage. Genes involved in muscle growth and development were upregulated, but those associated with responses to cellular stresses were downregulated. These data suggest that elimination of HIRA produces a hypertrophic response in skeletal muscle and leaves myofibers susceptible to stress-induced degeneration.
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Affiliation(s)
- Nicolas Valenzuela
- Department of Biology and Biochemistry, University of Houston, Houston, TX 77204, USA
| | - Benjamin Soibam
- Department of Computer Science and Engineering Technology, University of Houston-Downtown, Houston, TX 77002, USA
| | - Lerong Li
- Department of Bioinformatics and Computational Biology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Jing Wang
- Department of Bioinformatics and Computational Biology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Lauren A Byers
- Department of Thoracic Head & Neck Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Yu Liu
- Department of Biology and Biochemistry, University of Houston, Houston, TX 77204, USA
| | - Robert J Schwartz
- Department of Biology and Biochemistry, University of Houston, Houston, TX 77204, USA.,Stem Cell Engineering Department, Texas Heart Institute at St. Luke's Episcopal Hospital, Houston, TX 77030, USA
| | - M David Stewart
- Department of Biology and Biochemistry, University of Houston, Houston, TX 77204, USA .,Stem Cell Engineering Department, Texas Heart Institute at St. Luke's Episcopal Hospital, Houston, TX 77030, USA
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Talbert PB, Henikoff S. Histone variants on the move: substrates for chromatin dynamics. Nat Rev Mol Cell Biol 2016; 18:115-126. [PMID: 27924075 DOI: 10.1038/nrm.2016.148] [Citation(s) in RCA: 208] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Most histones are assembled into nucleosomes behind the replication fork to package newly synthesized DNA. By contrast, histone variants, which are encoded by separate genes, are typically incorporated throughout the cell cycle. Histone variants can profoundly change chromatin properties, which in turn affect DNA replication and repair, transcription, and chromosome packaging and segregation. Recent advances in the study of histone replacement have elucidated the dynamic processes by which particular histone variants become substrates of histone chaperones, ATP-dependent chromatin remodellers and histone-modifying enzymes. Here, we review histone variant dynamics and the effects of replacing DNA synthesis-coupled histones with their replication-independent variants on the chromatin landscape.
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Affiliation(s)
- Paul B Talbert
- Howard Hughes Medical Institute, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue North, Seattle, Washington 98109-1024, USA
| | - Steven Henikoff
- Howard Hughes Medical Institute, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue North, Seattle, Washington 98109-1024, USA
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Schiera G, Di Liegro CM, Puleo V, Colletta O, Fricano A, Cancemi P, Di Cara G, Di Liegro I. Extracellular vesicles shed by melanoma cells contain a modified form of H1.0 linker histone and H1.0 mRNA-binding proteins. Int J Oncol 2016; 49:1807-1814. [PMID: 27633859 PMCID: PMC5063456 DOI: 10.3892/ijo.2016.3692] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Accepted: 06/13/2016] [Indexed: 12/20/2022] Open
Abstract
Extracellular vesicles (EVs) are now recognized as a fundamental way for cell-to-cell horizontal transfer of properties, in both physiological and pathological conditions. Most of EV-mediated cross-talk among cells depend on the exchange of proteins, and nucleic acids, among which mRNAs, and non-coding RNAs such as different species of miRNAs. Cancer cells, in particular, use EVs to discard molecules which could be dangerous to them (for example differentiation-inducing proteins such as histone H1.0, or antitumor drugs), to transfer molecules which, after entering the surrounding cells, are able to transform their phenotype, and even to secrete factors, which allow escaping from immune surveillance. Herein we report that melanoma cells not only secrete EVs which contain a modified form of H1.0 histone, but also transport the corresponding mRNA. Given the already known role in tumorigenesis of some RNA binding proteins (RBPs), we also searched for proteins of this class in EVs. This study revealed the presence in A375 melanoma cells of at least three RBPs, with apparent MW of about 65, 45 and 38 kDa, which are able to bind H1.0 mRNA. Moreover, we purified one of these proteins, which by MALDI-TOF mass spectrometry was identified as the already known transcription factor MYEF2.
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Affiliation(s)
- Gabriella Schiera
- Department of Biological Chemical and Pharmaceutical Sciences and Technologies (STEBICEF), I-90128 Palermo, Italy
| | - Carlo Maria Di Liegro
- Department of Biological Chemical and Pharmaceutical Sciences and Technologies (STEBICEF), I-90128 Palermo, Italy
| | - Veronica Puleo
- Department of Biological Chemical and Pharmaceutical Sciences and Technologies (STEBICEF), I-90128 Palermo, Italy
| | - Oriana Colletta
- Department of Biological Chemical and Pharmaceutical Sciences and Technologies (STEBICEF), I-90128 Palermo, Italy
| | - Anna Fricano
- Department of Biological Chemical and Pharmaceutical Sciences and Technologies (STEBICEF), I-90128 Palermo, Italy
| | - Patrizia Cancemi
- Department of Biological Chemical and Pharmaceutical Sciences and Technologies (STEBICEF), I-90128 Palermo, Italy
| | - Gianluca Di Cara
- Center of Experimental Oncobiology (C.OB.S.), La Maddalena Hospital III Level Oncological Dept., Palermo, Italy
| | - Italia Di Liegro
- Department of Experimental Biomedicine and Clinical Neurosciences (BIONEC), University of Palermo, I-90127 Palermo, Italy
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Shih HT, Chen WY, Liu KY, Shih ZS, Chen YJ, Hsieh PC, Kuo KL, Huang KH, Hsu PH, Liu YW, Chan SP, Lee HH, Tsai YC, Wu JT. dBRWD3 Regulates Tissue Overgrowth and Ectopic Gene Expression Caused by Polycomb Group Mutations. PLoS Genet 2016; 12:e1006262. [PMID: 27588417 PMCID: PMC5010193 DOI: 10.1371/journal.pgen.1006262] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Accepted: 07/27/2016] [Indexed: 12/20/2022] Open
Abstract
To maintain a particular cell fate, a unique set of genes should be expressed while another set is repressed. One way to repress gene expression is through Polycomb group (PcG) proteins that compact chromatin into a silent configuration. In addition to cell fate maintenance, PcG proteins also maintain normal cell physiology, for example cell cycle. In the absence of PcG, ectopic activation of the PcG-repressed genes leads to developmental defects and malignant tumors. Little is known about the molecular nature of ectopic gene expression; especially what differentiates expression of a given gene in the orthotopic tissue (orthotopic expression) and the ectopic expression of the same gene due to PcG mutations. Here we present that ectopic gene expression in PcG mutant cells specifically requires dBRWD3, a negative regulator of HIRA/Yemanuclein (YEM)-mediated histone variant H3.3 deposition. dBRWD3 mutations suppress both the ectopic gene expression and aberrant tissue overgrowth in PcG mutants through a YEM-dependent mechanism. Our findings identified dBRWD3 as a critical regulator that is uniquely required for ectopic gene expression and aberrant tissue overgrowth caused by PcG mutations. Genetic information is stored in our genomic DNA, and different cells retrieve distinct sets of information from our genome. While it is important to activate genomic regions encoding proteins that are essential for a given cell type, it is equally important to silence genomic regions encoding proteins that are potentially harmful to this type of cells. One of the gene silencing mechanisms frequently used during and after development is mediated by the Polycomb group (PcG) proteins. If this guardian function does not perform correctly due to PcG mutations, genes that are normally silenced—such as oncogenes—are expressed aberrantly. Due to the activation of oncogenes and the loss of other PcG functions, PcG mutant cells often begin to display hallmarks of cancer, such as proliferating beyond control, acquiring stem-cell-like properties, and migrating to distant sites. If the transcriptional mechanisms underlying aberrant gene expression in PcG-mutant cancer cells differ from gene expression in normal cells, we may be able to selectively inhibit the growth of cancer cells without affecting their normal counterparts. Here we show that the difference between these two types of gene expression resides in their sensitivity to dBRWD3, a negative regulator of the deposition of histone H3 variant H3.3. Our results indicate that the inactivation of dBRWD3 or promotion of H3.3 deposition may selectively suppress ectopic gene expression and tumorigenesis driven by mutations in PcG.
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Affiliation(s)
- Hsueh-Tzu Shih
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Wei-Yu Chen
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Kwei-Yan Liu
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Zong-Siou Shih
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Yi-Jyun Chen
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Paul-Chen Hsieh
- Department of Anatomical Pathology, Far Eastern Memorial Hospital, New Taipei City, Taiwan
| | - Kuan-Lin Kuo
- Graduate Institute of Toxicology, National Taiwan University College of Medicine, Taipei, Taiwan
- Department of Urology, National Taiwan University College of Medicine and Hospital, Taipei, Taiwan
| | - Kuo-How Huang
- Department of Urology, National Taiwan University College of Medicine and Hospital, Taipei, Taiwan
| | - Pang-Hung Hsu
- Department of Bioscience and Biotechnology, National Taiwan Ocean University, Keelung, Taiwan
| | - Ya-Wen Liu
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Shih-Peng Chan
- Graduate Institute of Microbiology, College of Medicine, National Taiwan University, Taipei, Taiwan
- Genome and Systems Biology Degree Program, College of Life Science, National Taiwan University, Taipei, Taiwan
| | - Hsiu-Hsiang Lee
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Yu-Chen Tsai
- Department of Life Science and Life Science Center, Tunghai University, Taichung, Taiwan
- * E-mail: (YCT); (JTW)
| | - June-Tai Wu
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan
- * E-mail: (YCT); (JTW)
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Pinter SF. A Tale of Two Cities: How Xist and its partners localize to and silence the bicompartmental X. Semin Cell Dev Biol 2016; 56:19-34. [PMID: 27072488 DOI: 10.1016/j.semcdb.2016.03.023] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2016] [Revised: 03/30/2016] [Accepted: 03/30/2016] [Indexed: 10/22/2022]
Abstract
Sex chromosomal dosage compensation in mammals takes the form of X chromosome inactivation (XCI), driven by the non-coding RNA Xist. In contrast to dosage compensation systems of flies and worms, mammalian XCI has to restrict its function to the Xist-producing X chromosome, while leaving autosomes and active X untouched. The mechanisms behind the long-range yet cis-specific localization and silencing activities of Xist have long been enigmatic, but genomics, proteomics, super-resolution microscopy, and innovative genetic approaches have produced significant new insights in recent years. In this review, I summarize and integrate these findings with a particular focus on the redundant yet mutually reinforcing pathways that enable long-term transcriptional repression throughout the soma. This includes an exploration of concurrent epigenetic changes acting in parallel within two distinct compartments of the inactive X. I also examine how Polycomb repressive complexes 1 and 2 and macroH2A may bridge XCI establishment and maintenance. XCI is a remarkable phenomenon that operates across multiple scales, combining changes in nuclear architecture, chromosome topology, chromatin compaction, and nucleosome/nucleotide-level epigenetic cues. Learning how these pathways act in concert likely holds the answer to the riddle posed by Cattanach's and other autosomal translocations: What makes the X especially receptive to XCI?
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Affiliation(s)
- Stefan F Pinter
- Department of Genetics and Genome Sciences, Institute for Systems Genomics, University of Connecticut Health Center, 263 Farmington Ave, Farmington, CT 06030-6403, USA.
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