1
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Zhang L, Ye B, Xu Z, Li X, D M C, Shao Z. Genome-wide identification of mammalian cell-cycle invariant and mitotic-specific macroH2A1 domains. Biosci Trends 2023; 17:393-400. [PMID: 37778979 DOI: 10.5582/bst.2023.01214] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/03/2023]
Abstract
The histone variant macroH2A has been found to play important regulatory roles in genomic processes, especially in regulating transcriptomes. However, whether macroH2A nucleosomes are retained on mitotic chromosomes to enable maintenance of cell-specific transcriptomes is not known. Here, examining mouse embryonic fibroblast cells (NIH-3T3) with native chromatin immunoprecipitation and sequencing (nChIP-seq), we show that the overwhelming majority (~90%) of macroH2A1 domains identified at the G1/S stage are indeed stably retained on mitotic chromosomes. Unexpectedly though, we also find that there are a number of macroH2A domains that are specific for either mitotic or G1/S cells. Notably, more than 7,000 interphase expressed genes flanked by macroH2A1 domains are loaded with macroH2A1 nucleosomes on the mitotic chromosome to form extended domains. Overall, these results reveal that, while the majority of macroH2A1 domains are indeed faithfully transmitted through the mitotic chromosomes, there is a previously unknown cell-cycle dependent exchange of macroH2A1 nucleosomes at numerous genomic loci, indicating the existence of molecular machineries for this dynamically regulated process. We anticipate that these findings will prove to be essential for the integrity of mitotic progression and the maintenance of cellular identity.
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Affiliation(s)
- Le Zhang
- State Key Laboratory of Systems Medicine for Cancer, Shanghai Jiao Tong University, Shanghai, China
- Bio-ID Center, Shanghai Jiao Tong University, Shanghai, China
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Bishan Ye
- Bio-ID Center, Shanghai Jiao Tong University, Shanghai, China
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Zeqian Xu
- Bio-ID Center, Shanghai Jiao Tong University, Shanghai, China
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Xinhui Li
- Bio-ID Center, Shanghai Jiao Tong University, Shanghai, China
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Czajkowsky D M
- Bio-ID Center, Shanghai Jiao Tong University, Shanghai, China
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Zhifeng Shao
- State Key Laboratory of Systems Medicine for Cancer, Shanghai Jiao Tong University, Shanghai, China
- Bio-ID Center, Shanghai Jiao Tong University, Shanghai, China
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China
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2
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Zheng Y, Zhong G, He C, Li M. Targeted splicing therapy: new strategies for colorectal cancer. Front Oncol 2023; 13:1222932. [PMID: 37664052 PMCID: PMC10470845 DOI: 10.3389/fonc.2023.1222932] [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: 05/15/2023] [Accepted: 08/07/2023] [Indexed: 09/05/2023] Open
Abstract
RNA splicing is the process of forming mature mRNA, which is an essential phase necessary for gene expression and controls many aspects of cell proliferation, survival, and differentiation. Abnormal gene-splicing events are closely related to the development of tumors, and the generation of oncogenic isoform in splicing can promote tumor progression. As a main process of tumor-specific splicing variants, alternative splicing (AS) can promote tumor progression by increasing the production of oncogenic splicing isoforms and/or reducing the production of normal splicing isoforms. This is the focus of current research on the regulation of aberrant tumor splicing. So far, AS has been found to be associated with various aspects of tumor biology, including cell proliferation and invasion, resistance to apoptosis, and sensitivity to different chemotherapeutic drugs. This article will review the abnormal splicing events in colorectal cancer (CRC), especially the tumor-associated splicing variants arising from AS, aiming to offer an insight into CRC-targeted splicing therapy.
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Affiliation(s)
| | | | - Chengcheng He
- Department of Gastroenterology, The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong, China
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3
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Beierle JA, Yao EJ, Goldstein SI, Scotellaro JL, Sena KD, Linnertz CA, Willits AB, Kader L, Young EE, Peltz G, Emili A, Ferris MT, Bryant CD. Genetic basis of thermal nociceptive sensitivity and brain weight in a BALB/c reduced complexity cross. Mol Pain 2022; 18:17448069221079540. [PMID: 35088629 PMCID: PMC8891926 DOI: 10.1177/17448069221079540] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Accepted: 01/20/2022] [Indexed: 11/30/2022] Open
Abstract
Thermal nociception involves the transmission of temperature-related noxious information from the periphery to the CNS and is a heritable trait that could predict transition to persistent pain. Rodent forward genetics complement human studies by controlling genetic complexity and environmental factors, analysis of end point tissue, and validation of variants on appropriate genetic backgrounds. Reduced complexity crosses between nearly identical inbred substrains with robust trait differences can greatly facilitate unbiased discovery of novel genes and variants. We found BALB/cByJ mice showed enhanced sensitivity on the 53.5°C hot plate and mechanical stimulation in the von Frey test compared to BALB/cJ mice and replicated decreased gross brain weight in BALB/cByJ versus BALB/cJ. We then identified a quantitative trait locus (QTL) on chromosome 13 for hot plate sensitivity (LOD = 10.7; p < 0.001; peak = 56 Mb) and a QTL for brain weight on chromosome 5 (LOD = 8.7; p < 0.001). Expression QTL mapping of brain tissues identified H2afy (56.07 Mb) as the top transcript with the strongest association at the hot plate locus (FDR = 0.0002) and spliceome analysis identified differential exon usage within H2afy associated with the same locus. Whole brain proteomics further supported decreased H2AFY expression could underlie enhanced hot plate sensitivity, and identified ACADS as a candidate for reduced brain weight. To summarize, a BALB/c reduced complexity cross combined with multiple-omics approaches facilitated identification of candidate genes underlying thermal nociception and brain weight. These substrains provide a powerful, reciprocal platform for future validation of candidate variants.
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Affiliation(s)
- Jacob A Beierle
- Program in Biomolecular Pharmacology, Boston University School of Medicine, Boston, MA, USA
- Laboratory of Addiction Genetics, Department of Pharmacology and Experimental Therapeutics and Psychiatry, Boston University School of Medicine, Boston, MA, USA
| | - Emily J Yao
- Laboratory of Addiction Genetics, Department of Pharmacology and Experimental Therapeutics and Psychiatry, Boston University School of Medicine, Boston, MA, USA
| | - Stanley I Goldstein
- Program in Biomolecular Pharmacology, Boston University School of Medicine, Boston, MA, USA
- Department of Biology and Biochemistry, Center for Network Systems Biology, Boston University School of Medicine, Boston, MA, USA
| | - Julia L Scotellaro
- Department of Biology and Biochemistry, Center for Network Systems Biology, Boston University School of Medicine, Boston, MA, USA
- Undergraduate Research Opportunity Program, Boston University, Boston, MA, USA
| | - Katherine D Sena
- Department of Biology and Biochemistry, Center for Network Systems Biology, Boston University School of Medicine, Boston, MA, USA
- Undergraduate Research Opportunity Program, Boston University, Boston, MA, USA
| | - Colton A Linnertz
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Adam B Willits
- Neuroscience Program, University of Kansas Medical Center, Kansas City, KS, USA
| | - Leena Kader
- Neuroscience Program, University of Kansas Medical Center, Kansas City, KS, USA
| | - Erin E Young
- Department of Anesthesiology, University of Kansas Medical Center, Kansas City, KS, USA
| | - Gary Peltz
- Department of Anesthesiology, Pain, and Preoperative Medicine, Stanford University School of Medicine, Stanford, CA, USA
| | - Andrew Emili
- Department of Biology and Biochemistry, Center for Network Systems Biology, Boston University School of Medicine, Boston, MA, USA
| | - Martin T Ferris
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Camron D Bryant
- Laboratory of Addiction Genetics, Department of Pharmacology and Experimental Therapeutics and Psychiatry, Boston University School of Medicine, Boston, MA, USA
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4
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Caron P, Pobega E, Polo SE. DNA Double-Strand Break Repair: All Roads Lead to HeterochROMAtin Marks. Front Genet 2021; 12:730696. [PMID: 34539757 PMCID: PMC8440905 DOI: 10.3389/fgene.2021.730696] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Accepted: 08/06/2021] [Indexed: 12/21/2022] Open
Abstract
In response to DNA double-strand breaks (DSBs), chromatin modifications orchestrate DNA repair pathways thus safeguarding genome integrity. Recent studies have uncovered a key role for heterochromatin marks and associated factors in shaping DSB repair within the nucleus. In this review, we present our current knowledge of the interplay between heterochromatin marks and DSB repair. We discuss the impact of heterochromatin features, either pre-existing in heterochromatin domains or de novo established in euchromatin, on DSB repair pathway choice. We emphasize how heterochromatin decompaction and mobility further support DSB repair, focusing on recent mechanistic insights into these processes. Finally, we speculate about potential molecular players involved in the maintenance or the erasure of heterochromatin marks following DSB repair, and their implications for restoring epigenome function and integrity.
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Affiliation(s)
- Pierre Caron
- Epigenetics and Cell Fate Centre, CNRS, University of Paris, Paris, France
| | - Enrico Pobega
- Epigenetics and Cell Fate Centre, CNRS, University of Paris, Paris, France
| | - Sophie E Polo
- Epigenetics and Cell Fate Centre, CNRS, University of Paris, Paris, France
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5
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Kim SP, Srivatsan SN, Chavez M, Shirai CL, White BS, Ahmed T, Alberti MO, Shao J, Nunley R, White LS, Bednarski J, Pehrson JR, Walter MJ. Mutant U2AF1-induced alternative splicing of H2afy (macroH2A1) regulates B-lymphopoiesis in mice. Cell Rep 2021; 36:109626. [PMID: 34469727 PMCID: PMC8454217 DOI: 10.1016/j.celrep.2021.109626] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 05/19/2021] [Accepted: 08/05/2021] [Indexed: 12/13/2022] Open
Abstract
Somatic mutations in spliceosome genes are found in ∼50% of patients with myelodysplastic syndromes (MDS), a myeloid malignancy associated with low blood counts. Expression of the mutant splicing factor U2AF1(S34F) alters hematopoiesis and mRNA splicing in mice. Our understanding of the functionally relevant alternatively spliced target genes that cause hematopoietic phenotypes in vivo remains incomplete. Here, we demonstrate that reduced expression of H2afy1.1, an alternatively spliced isoform of the histone H2A variant gene H2afy, is responsible for reduced B cells in U2AF1(S34F) mice. Deletion of H2afy or expression of U2AF1(S34F) reduces expression of Ebf1 (early B cell factor 1), a key transcription factor for B cell development, and mechanistically, H2AFY is enriched at the EBF1 promoter. Induced expression of H2AFY1.1 in U2AF1(S34F) cells rescues reduced EBF1 expression and B cells numbers in vivo. Collectively, our data implicate alternative splicing of H2AFY as a contributor to lymphopenia induced by U2AF1(S34F) in mice and MDS.
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Affiliation(s)
- Sanghyun P Kim
- Division of Oncology, Department of Internal Medicine, Washington University School of Medicine, St Louis, MO 63110, USA
| | - Sridhar N Srivatsan
- Division of Oncology, Department of Internal Medicine, Washington University School of Medicine, St Louis, MO 63110, USA
| | - Monique Chavez
- Division of Oncology, Department of Internal Medicine, Washington University School of Medicine, St Louis, MO 63110, USA
| | - Cara L Shirai
- Department of Pathology and Immunology, Washington University School of Medicine, St Louis, MO 63110, USA
| | - Brian S White
- Division of Oncology, Department of Internal Medicine, Washington University School of Medicine, St Louis, MO 63110, USA
| | - Tanzir Ahmed
- Division of Oncology, Department of Internal Medicine, Washington University School of Medicine, St Louis, MO 63110, USA
| | - Michael O Alberti
- Department of Pathology and Immunology, Washington University School of Medicine, St Louis, MO 63110, USA
| | - Jin Shao
- Division of Oncology, Department of Internal Medicine, Washington University School of Medicine, St Louis, MO 63110, USA
| | - Ryan Nunley
- Department of Orthopedic Surgery, Washington University School of Medicine, Barnes-Jewish Hospital, St. Louis, MO 63110, USA
| | - Lynn S White
- Department of Pediatrics, Washington University School of Medicine, St Louis, MO 63110, USA
| | - Jeff Bednarski
- Department of Pediatrics, Washington University School of Medicine, St Louis, MO 63110, USA
| | - John R Pehrson
- Department of Animal Biology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Matthew J Walter
- Division of Oncology, Department of Internal Medicine, Washington University School of Medicine, St Louis, MO 63110, USA.
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6
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Broggi G, Filetti V, Ieni A, Rapisarda V, Ledda C, Vitale E, Varricchio S, Russo D, Lombardo C, Tuccari G, Caltabiano R, Loreto C. MacroH2A1 Immunoexpression in Breast Cancer. Front Oncol 2020; 10:1519. [PMID: 32974186 PMCID: PMC7471871 DOI: 10.3389/fonc.2020.01519] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2020] [Accepted: 07/15/2020] [Indexed: 12/11/2022] Open
Abstract
MacroH2A1 has two splice isoforms, macroH2A1.1 and macroH2A1.2, that have been studied in several form of cancer. In the literature there are not many scientific papers dealing with the role of macroH2A1 in breast cancer. Breast cancer is the most frequent form of malignancy in females. It tend to metastasize to the bone in ~70% of patients. Despite treatment, new bone metastases will still occur in 30–50% of cases with advanced disease. Overall 5-year survival after the diagnosis of bone metastasis is ~20%. Osteoclasts and osteoblasts of the bone microenvironment are engaged by soluble factors released by neoplastic cells, resulting in bone matrix breakdown. This malfunction enhances the proliferation of the cancer cells, creating a vicious cycle. We investigated immunohistochemical expression of macroH2A1 in primitive breast cancer, focusing on the comparison of metastatic and non-metastatic cases. Furthermore, the immunohistochemical expression of macroH2A1 has been evaluated both in all cases of nodal metastases and in distant metastases. Our data demonstrated that macroH2A1 expression was higher expressed in metastatic breast cancer (77%) vs. non-metastatic breast cancer (32%). Also in analyzed metastases cases, a high macroH2A1 expression was detected: 85 and 80% in nodal and distant metastases cases, respectively. These results supported the fact that macroH2A1 is more highly expressed in breast cancer with worst prognosis.
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Affiliation(s)
- Giuseppe Broggi
- Section of Anatomic Pathology, Department Gian Filippo Ingrassia, University of Catania, Catania, Italy
| | - Veronica Filetti
- Human Anatomy and Histology, Department of Biomedical and Biotechnology Sciences, University of Catania, Catania, Italy
| | - Antonio Ieni
- Department of Human Pathology in Adult and Developmental Age "Gaetano Barresi", Section of Pathology, University of Messina, Messina, Italy
| | - Venerando Rapisarda
- Occupational Medicine, Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy
| | - Caterina Ledda
- Occupational Medicine, Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy
| | - Ermanno Vitale
- Occupational Medicine, Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy
| | - Silvia Varricchio
- Department of Advanced Biomedical Sciences, Pathology Unit, University of Naples Federico II, Naples, Italy
| | - Daniela Russo
- Department of Advanced Biomedical Sciences, Pathology Unit, University of Naples Federico II, Naples, Italy
| | - Claudia Lombardo
- Human Anatomy and Histology, Department of Biomedical and Biotechnology Sciences, University of Catania, Catania, Italy
| | - Giovanni Tuccari
- Department of Human Pathology in Adult and Developmental Age "Gaetano Barresi", Section of Pathology, University of Messina, Messina, Italy
| | - Rosario Caltabiano
- Section of Anatomic Pathology, Department Gian Filippo Ingrassia, University of Catania, Catania, Italy
| | - Carla Loreto
- Human Anatomy and Histology, Department of Biomedical and Biotechnology Sciences, University of Catania, Catania, Italy
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7
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Histone variant macroH2A: from chromatin deposition to molecular function. Essays Biochem 2019; 63:59-74. [DOI: 10.1042/ebc20180062] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Revised: 02/28/2019] [Accepted: 03/01/2019] [Indexed: 01/01/2023]
Abstract
Abstract
The eukaryotic genome is regulated in the context of chromatin. Specialized histones, known as histone variants, incorporate into chromatin to replace their canonical counterparts and represent an important layer of regulation to diversify the structural characteristics and functional outputs of chromatin. MacroH2A is an unusual histone variant with a bulky C-terminal non-histone domain that distinguishes it from all other histones. It is a critical player in stabilizing differentiated cell identity by posing as a barrier to somatic cell reprogramming toward pluripotency and acts as a tumor suppressor in a wide range of cancers. MacroH2A histones are generally regarded as repressive variants that are enriched at the inactive X chromosome (Xi) and broad domains across autosomal chromatin. Recent studies have shed light on to how macroH2A influences transcriptional outputs within distinct genomic contexts and revealed new intriguing molecular functions of macroH2A variants beyond transcriptional regulation. Furthermore, the mechanisms of its mysterious chromatin deposition are beginning to be unraveled, facilitating our understanding of its complex regulation of genome function.
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8
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Cedeno RJ, Nakauka-Ddamba A, Yousefi M, Sterling S, Leu NA, Li N, Pehrson JR, Lengner CJ. The histone variant macroH2A confers functional robustness to the intestinal stem cell compartment. PLoS One 2017; 12:e0185196. [PMID: 28934364 PMCID: PMC5608326 DOI: 10.1371/journal.pone.0185196] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Accepted: 09/07/2017] [Indexed: 12/20/2022] Open
Abstract
A stem cell's epigenome directs cell fate during development, homeostasis, and regeneration. Epigenetic dysregulation can lead to inappropriate cell fate decisions, aberrant cell function, and even cancer. The histone variant macroH2A has been shown to influence gene expression, guide cell fate, and safeguard against genotoxic stress. Interestingly, mice lacking functional macroH2A histones (hereafter referred to as macroH2A DKO) are viable and fertile; yet suffer from increased perinatal death and reduced weight and size compared to wildtype (WT). Here, we ask whether the ostensible reduced vigor of macroH2A DKO mice extends to intestinal stem cell (ISC) function during homeostasis, regeneration, and oncogenesis. Lgr5-eGFP-IRES-CreERT2 or Hopx-CreERT2::Rosa26-LSL-tdTomato ISC reporter mice or the C57BL/6J-Apcmin/J murine intestinal adenoma model were bred into a macroH2A DKO or strain-matched WT background and assessed for ISC functionality, regeneration and tumorigenesis. High-dose (12Gy) whole-body γ-irradiation was used as an injury model. We show that macroH2A is dispensable for intestinal homeostasis and macroH2A DKO mice have similar numbers of active crypt-base columnar ISCs (CBCs). MacroH2A DKO intestine exhibits impaired regeneration following injury, despite having significantly more putative reserve ISCs. DKO reserve ISCs disproportionately undergo apoptosis compared to WT after DNA damage infliction. Interestingly, a macroH2A DKO background does not significantly increase tumorigenesis in the Apcmin model of intestinal adenoma. We conclude that macroH2A influences reserve ISC number and function during homeostasis and regeneration. These data suggest macroH2A enhances reserve ISC survival after DNA damage and thus confers functional robustness to the intestinal epithelium.
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Affiliation(s)
- Ryan James Cedeno
- Department of Biomedical Sciences, University of Pennsylvania School of Veterinary Medicine, Philadelphia, Pennsylvania, United States of America.,Cell and Molecular Biology Graduate Program, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, United States of America
| | - Angela Nakauka-Ddamba
- Department of Biomedical Sciences, University of Pennsylvania School of Veterinary Medicine, Philadelphia, Pennsylvania, United States of America
| | - Maryam Yousefi
- Department of Biomedical Sciences, University of Pennsylvania School of Veterinary Medicine, Philadelphia, Pennsylvania, United States of America.,Cell and Molecular Biology Graduate Program, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, United States of America
| | - Stephanie Sterling
- Department of Biomedical Sciences, University of Pennsylvania School of Veterinary Medicine, Philadelphia, Pennsylvania, United States of America.,Center for Animal Transgenesis, University of Pennsylvania School of Veterinary Medicine, Philadelphia, Pennsylvania, United States of America
| | - Nicolae Adrian Leu
- Department of Biomedical Sciences, University of Pennsylvania School of Veterinary Medicine, Philadelphia, Pennsylvania, United States of America.,Center for Animal Transgenesis, University of Pennsylvania School of Veterinary Medicine, Philadelphia, Pennsylvania, United States of America
| | - Ning Li
- Department of Biomedical Sciences, University of Pennsylvania School of Veterinary Medicine, Philadelphia, Pennsylvania, United States of America
| | - John R Pehrson
- Department of Biomedical Sciences, University of Pennsylvania School of Veterinary Medicine, Philadelphia, Pennsylvania, United States of America
| | - Christopher Joachim Lengner
- Department of Biomedical Sciences, University of Pennsylvania School of Veterinary Medicine, Philadelphia, Pennsylvania, United States of America.,Center for Animal Transgenesis, University of Pennsylvania School of Veterinary Medicine, Philadelphia, Pennsylvania, United States of America.,Center for Molecular Studies in Digestive and Liver Disease, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America.,Institute for Regenerative Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
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9
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Douet J, Corujo D, Malinverni R, Renauld J, Sansoni V, Posavec Marjanović M, Cantariño N, Valero V, Mongelard F, Bouvet P, Imhof A, Thiry M, Buschbeck M. MacroH2A histone variants maintain nuclear organization and heterochromatin architecture. J Cell Sci 2017; 130:1570-1582. [PMID: 28283545 DOI: 10.1242/jcs.199216] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Accepted: 03/07/2017] [Indexed: 12/15/2022] Open
Abstract
Genetic loss-of-function studies on development, cancer and somatic cell reprogramming have suggested that the group of macroH2A histone variants might function through stabilizing the differentiated state by a yet unknown mechanism. Here, we present results demonstrating that macroH2A variants have a major function in maintaining nuclear organization and heterochromatin architecture. Specifically, we find that a substantial amount of macroH2A is associated with heterochromatic repeat sequences. We further identify macroH2A on sites of interstitial heterochromatin decorated by histone H3 trimethylated on K9 (H3K9me3). Loss of macroH2A leads to major defects in nuclear organization, including reduced nuclear circularity, disruption of nucleoli and a global loss of dense heterochromatin. Domains formed by DNA repeat sequences are disorganized, expanded and fragmented, and mildly re-expressed when depleted of macroH2A. At the molecular level, we find that macroH2A is required for the interaction of repeat sequences with the nucleostructural protein lamin B1. Taken together, our results argue that a major function of macroH2A histone variants is to link nucleosome composition to higher-order chromatin architecture.
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Affiliation(s)
- Julien Douet
- Josep Carreras Leukaemia Research Institute (IJC), Campus ICO - Germans Trias i Pujol, Campus Can Ruti, Badalona 08916, Spain
- Program of Predictive and Personalized Medicine of Cancer, Germans Trias and Pujol Research Institute (PMPPC-IGTP), Campus Can Ruti, Badalona 08916, Spain
| | - David Corujo
- Josep Carreras Leukaemia Research Institute (IJC), Campus ICO - Germans Trias i Pujol, Campus Can Ruti, Badalona 08916, Spain
- Program of Predictive and Personalized Medicine of Cancer, Germans Trias and Pujol Research Institute (PMPPC-IGTP), Campus Can Ruti, Badalona 08916, Spain
| | - Roberto Malinverni
- Josep Carreras Leukaemia Research Institute (IJC), Campus ICO - Germans Trias i Pujol, Campus Can Ruti, Badalona 08916, Spain
- Program of Predictive and Personalized Medicine of Cancer, Germans Trias and Pujol Research Institute (PMPPC-IGTP), Campus Can Ruti, Badalona 08916, Spain
| | - Justine Renauld
- Cell and tissue biology unit, GIGA-Neurosciences, University of Liege, C.H.U. Sart Tilman, Liege 4000, Belgium
| | - Viola Sansoni
- BioMedical Center and Center for Integrated Protein Sciences Munich, Ludwig-Maximilians-University of Munich, Großhaderner Straße 9, Planegg-Martinsried 82152, Germany
| | - Melanija Posavec Marjanović
- Josep Carreras Leukaemia Research Institute (IJC), Campus ICO - Germans Trias i Pujol, Campus Can Ruti, Badalona 08916, Spain
| | - Neus Cantariño
- Josep Carreras Leukaemia Research Institute (IJC), Campus ICO - Germans Trias i Pujol, Campus Can Ruti, Badalona 08916, Spain
| | - Vanesa Valero
- Josep Carreras Leukaemia Research Institute (IJC), Campus ICO - Germans Trias i Pujol, Campus Can Ruti, Badalona 08916, Spain
- Program of Predictive and Personalized Medicine of Cancer, Germans Trias and Pujol Research Institute (PMPPC-IGTP), Campus Can Ruti, Badalona 08916, Spain
| | - Fabien Mongelard
- Université de Lyon, Ecole normale Supérieure de Lyon, Centre de Recherche en Cancérologie de Lyon, Cancer Cell Plasticity Department, UMR INSERM 1052 CNRS5286, Centre Léon Bérard, 69008 Lyon, France
| | - Philippe Bouvet
- Université de Lyon, Ecole normale Supérieure de Lyon, Centre de Recherche en Cancérologie de Lyon, Cancer Cell Plasticity Department, UMR INSERM 1052 CNRS5286, Centre Léon Bérard, 69008 Lyon, France
| | - Axel Imhof
- BioMedical Center and Center for Integrated Protein Sciences Munich, Ludwig-Maximilians-University of Munich, Großhaderner Straße 9, Planegg-Martinsried 82152, Germany
| | - Marc Thiry
- Cell and tissue biology unit, GIGA-Neurosciences, University of Liege, C.H.U. Sart Tilman, Liege 4000, Belgium
| | - Marcus Buschbeck
- Josep Carreras Leukaemia Research Institute (IJC), Campus ICO - Germans Trias i Pujol, Campus Can Ruti, Badalona 08916, Spain
- Program of Predictive and Personalized Medicine of Cancer, Germans Trias and Pujol Research Institute (PMPPC-IGTP), Campus Can Ruti, Badalona 08916, Spain
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10
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Unusual maintenance of X chromosome inactivation predisposes female lymphocytes for increased expression from the inactive X. Proc Natl Acad Sci U S A 2016; 113:E2029-38. [PMID: 27001848 DOI: 10.1073/pnas.1520113113] [Citation(s) in RCA: 178] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Females have a greater immunological advantage than men, yet they are more prone to autoimmune disorders. The basis for this sex bias lies in the X chromosome, which contains many immunity-related genes. Female mammals use X chromosome inactivation (XCI) to generate a transcriptionally silent inactive X chromosome (Xi) enriched with heterochromatic modifications and XIST/Xist RNA, which equalizes gene expression between the sexes. Here, we examine the maintenance of XCI in lymphocytes from females in mice and humans. Strikingly, we find that mature naïve T and B cells have dispersed patterns of XIST/Xist RNA, and they lack the typical heterochromatic modifications of the Xi. In vitro activation of lymphocytes triggers the return of XIST/Xist RNA transcripts and some chromatin marks (H3K27me3, ubiquitin-H2A) to the Xi. Single-cell RNA FISH analysis of female T cells revealed that the X-linked immunity genes CD40LG and CXCR3 are biallelically expressed in some cells. Using knockout and knockdown approaches, we find that Xist RNA-binding proteins, YY1 and hnRNPU, are critical for recruitment of XIST/Xist RNA back to the Xi. Furthermore, we examined B cells from patients with systemic lupus erythematosus, an autoimmune disorder with a strong female bias, and observed different XIST RNA localization patterns, evidence of biallelic expression of immunity-related genes, and increased transcription of these genes. We propose that the Xi in female lymphocytes is predisposed to become partially reactivated and to overexpress immunity-related genes, providing the first mechanistic evidence to our knowledge for the enhanced immunity of females and their increased susceptibility for autoimmunity.
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11
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Borghesan M, Fusilli C, Rappa F, Panebianco C, Rizzo G, Oben JA, Mazzoccoli G, Faulkes C, Pata I, Agodi A, Rezaee F, Minogue S, Warren A, Peterson A, Sedivy JM, Douet J, Buschbeck M, Cappello F, Mazza T, Pazienza V, Vinciguerra M. DNA Hypomethylation and Histone Variant macroH2A1 Synergistically Attenuate Chemotherapy-Induced Senescence to Promote Hepatocellular Carcinoma Progression. Cancer Res 2016; 76:594-606. [PMID: 26772755 DOI: 10.1158/0008-5472.can-15-1336] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Accepted: 11/02/2015] [Indexed: 12/11/2022]
Abstract
Aging is a major risk factor for progression of liver diseases to hepatocellular carcinoma (HCC). Cellular senescence contributes to age-related tissue dysfunction, but the epigenetic basis underlying drug-induced senescence remains unclear. macroH2A1, a variant of histone H2A, is a marker of senescence-associated heterochromatic foci that synergizes with DNA methylation to silence tumor-suppressor genes in human fibroblasts. In this study, we investigated the relationship between macroH2A1 splice variants, macroH2A1.1 and macroH2A1.2, and liver carcinogenesis. We found that protein levels of both macroH2A1 isoforms were increased in the livers of very elderly rodents and humans, and were robust immunohistochemical markers of human cirrhosis and HCC. In response to the chemotherapeutic and DNA-demethylating agent 5-aza-deoxycytidine (5-aza-dC), transgenic expression of macroH2A1 isoforms in HCC cell lines prevented the emergence of a senescent-like phenotype and induced synergistic global DNA hypomethylation. Conversely, macroH2A1 depletion amplified the antiproliferative effects of 5-aza-dC in HCC cells, but failed to enhance senescence. Senescence-associated secretory phenotype and whole-transcriptome analyses implicated the p38 MAPK/IL8 pathway in mediating macroH2A1-dependent escape of HCC cells from chemotherapy-induced senescence. Furthermore, chromatin immunoprecipitation sequencing revealed that this hepatic antisenescence state also required active transcription that could not be attributed to genomic occupancy of these histones. Collectively, our findings reveal a new mechanism by which drug-induced senescence is epigenetically regulated by macroH2A1 and DNA methylation and suggest macroH2A1 as a novel biomarker of hepatic senescence that could potentially predict prognosis and disease progression.
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Affiliation(s)
- Michela Borghesan
- Institute for Liver and Digestive Health, Royal Free Hospital, University College London, London, United Kingdom. Division of Internal Medicine, Department of Medical Sciences, IRCCS "Casa Sollievo della Sofferenza" Hospital, San Giovanni Rotondo, Italy
| | - Caterina Fusilli
- Bioinformatics Unit, IRCCS "Casa Sollievo della Sofferenza"-Mendel Laboratory, Rome, Italy
| | - Francesca Rappa
- Department of Experimental Biomedicine and Clinical Neurosciences, Section of Human Anatomy, University of Palermo, Palermo, Italy
| | - Concetta Panebianco
- Gastroenterology Unit, IRCCS "Casa Sollievo della Sofferenza" Hospital, San Giovanni Rotondo, Italy
| | - Giovanni Rizzo
- Institute for Liver and Digestive Health, Royal Free Hospital, University College London, London, United Kingdom
| | - Jude A Oben
- Institute for Liver and Digestive Health, Royal Free Hospital, University College London, London, United Kingdom
| | - Gianluigi Mazzoccoli
- Division of Internal Medicine, Department of Medical Sciences, IRCCS "Casa Sollievo della Sofferenza" Hospital, San Giovanni Rotondo, Italy
| | - Chris Faulkes
- School of Biological and Chemical Sciences, Queen Mary University of London, London, United Kingdom
| | - Illar Pata
- Department of Gene Technology, Tallinn University of Technology (TTU), IVEX Lab, Tallinn, Estonia
| | - Antonella Agodi
- Department GF Ingrassia, University of Catania, Catania, Italy
| | - Farhad Rezaee
- Department of Cell Biology, University Medical Center Groningen, Groningen, the Netherlands
| | - Shane Minogue
- Institute for Liver and Digestive Health, Royal Free Hospital, University College London, London, United Kingdom
| | - Alessandra Warren
- Institute for Liver and Digestive Health, Royal Free Hospital, University College London, London, United Kingdom. Centre for Education and Research on Aging (CERA) and the ANZAC Research Institute, Concord RG Hospital, University of Sydney, Sydney, Australia
| | - Abigail Peterson
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, Rhode Island
| | - John M Sedivy
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, Rhode Island
| | - Julien Douet
- Institute for Predictive and Personalized Medicine of Cancer, Campus Can Ruti, Badalona, Spain. Josep Carreras Institute for Leukaemia Research, Campus ICO-HGTP, Campus Can Ruti, Badalona, Spain
| | - Marcus Buschbeck
- Institute for Predictive and Personalized Medicine of Cancer, Campus Can Ruti, Badalona, Spain. Josep Carreras Institute for Leukaemia Research, Campus ICO-HGTP, Campus Can Ruti, Badalona, Spain
| | - Francesco Cappello
- Department of Experimental Biomedicine and Clinical Neurosciences, Section of Human Anatomy, University of Palermo, Palermo, Italy. Euro-Mediterranean Institute of Science and Technology (IEMEST), Palermo, Italy
| | - Tommaso Mazza
- Bioinformatics Unit, IRCCS "Casa Sollievo della Sofferenza"-Mendel Laboratory, Rome, Italy
| | - Valerio Pazienza
- Gastroenterology Unit, IRCCS "Casa Sollievo della Sofferenza" Hospital, San Giovanni Rotondo, Italy
| | - Manlio Vinciguerra
- Institute for Liver and Digestive Health, Royal Free Hospital, University College London, London, United Kingdom. Gastroenterology Unit, IRCCS "Casa Sollievo della Sofferenza" Hospital, San Giovanni Rotondo, Italy. Euro-Mediterranean Institute of Science and Technology (IEMEST), Palermo, Italy. School of Science and Technology, Nottingham Trent University, Nottingham, United Kingdom.
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12
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Won KJ, Choi I, LeRoy G, Zee BM, Sidoli S, Gonzales-Cope M, Garcia BA. Proteogenomics analysis reveals specific genomic orientations of distal regulatory regions composed by non-canonical histone variants. Epigenetics Chromatin 2015; 8:13. [PMID: 25878728 PMCID: PMC4397702 DOI: 10.1186/s13072-015-0005-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Accepted: 03/19/2015] [Indexed: 01/05/2023] Open
Abstract
Background Histone variants play further important roles in DNA packaging and controlling gene expression. However, our understanding about their composition and their functions is limited. Results Integrating proteomic and genomic approaches, we performed a comprehensive analysis of the epigenetic landscapes containing the four histone variants H3.1, H3.3, H2A.Z, and macroH2A. These histones were FLAG-tagged in HeLa cells and purified using chromatin immunoprecipitation (ChIP). By adopting ChIP followed by mass spectrometry (ChIP-MS), we quantified histone post-translational modifications (PTMs) and histone variant nucleosomal ratios in highly purified mononucleosomes. Subsequent ChIP followed by next-generation sequencing (ChIP-seq) was used to map the genome-wide localization of the analyzed histone variants and define their chromatin domains. Finally, we included in our study large datasets contained in the ENCODE database. We newly identified a group of regulatory regions enriched in H3.1 and the histone variant associated with repressive marks macroH2A. Systematic analysis identified both symmetric and asymmetric patterns of histone variant occupancies at intergenic regulatory regions. Strikingly, these directional patterns were associated with RNA polymerase II (PolII). These asymmetric patterns correlated with the enhancer activities measured using global run-on sequencing (GRO-seq) data. Conclusions Our studies show that H2A.Z and H3.3 delineate the orientation of transcription at enhancers as observed at promoters. We also showed that enhancers with skewed histone variant patterns well facilitate enhancer activity. Collectively, our study indicates that histone variants are deposited at regulatory regions to assist gene regulation. Electronic supplementary material The online version of this article (doi:10.1186/s13072-015-0005-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Kyoung-Jae Won
- The Institute for Diabetes, Obesity, and Metabolism, Philadelphia, PA 19104 USA.,Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104 USA
| | - Inchan Choi
- The Institute for Diabetes, Obesity, and Metabolism, Philadelphia, PA 19104 USA.,Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104 USA.,Department of Agricultural Biotechnology, National Academy of Agricultural Science, 370 Nongsaengmyeong-ro, Wansan-gu, Jeonju-si, Jeollabuk-do 560-500 South Korea
| | - Gary LeRoy
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544 USA
| | - Barry M Zee
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544 USA.,Epigenetics Program, Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104 USA
| | - Simone Sidoli
- Epigenetics Program, Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104 USA
| | - Michelle Gonzales-Cope
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544 USA.,Epigenetics Program, Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104 USA
| | - Benjamin A Garcia
- Epigenetics Program, Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104 USA
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13
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Abstract
MacroH2A core histone variants have a unique structure that includes a C-terminal nonhistone domain. They are highly conserved in vertebrates and are thought to regulate gene expression. However, the nature of genes regulated by macroH2As and their biological significance remain unclear. Here, we examine macroH2A function in vivo by knocking out both macroH2A1 and macroH2A2 in the mouse. While macroH2As are not required for early development, the absence of macroH2As impairs prenatal and postnatal growth and can significantly reduce reproductive efficiency. The distributions of macroH2A.1- and macroH2A.2-containing nucleosomes show substantial overlap, as do their effects on gene expression. Our studies in fetal and adult liver indicate that macroH2As can exert large positive or negative effects on gene expression, with macroH2A.1 and macroH2A.2 acting synergistically on the expression of some genes and apparently having opposing effects on others. These effects are very specific and in the adult liver preferentially involve genes related to lipid metabolism, including the leptin receptor. MacroH2A-dependent gene regulation changes substantially in postnatal development and can be strongly affected by fasting. We propose that macroH2As produce adaptive changes to gene expression, which in the liver focus on metabolism.
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14
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Chen H, Ruiz PD, Novikov L, Casill AD, Park JW, Gamble MJ. MacroH2A1.1 and PARP-1 cooperate to regulate transcription by promoting CBP-mediated H2B acetylation. Nat Struct Mol Biol 2014; 21:981-9. [PMID: 25306110 PMCID: PMC4221384 DOI: 10.1038/nsmb.2903] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2014] [Accepted: 09/16/2014] [Indexed: 12/29/2022]
Abstract
The histone variant macroH2A1 regulates gene expression important for differentiation, stem cell reprogramming and tumor suppression. Here, we demonstrate that in primary human cells, macroH2A1 participates in two physically and functionally distinct types of chromatin either marked by H3K27me3 or nine histone acetylations. Using RNA-seq, we found that macroH2A1-regulated genes, which have roles in cancer progression, are specifically found in macroH2A1-containing acetylated chromatin. Of the two macroH2A1 variants, macroH2A1.1 and macroH2A1.2, the former is suppressed in cancer and can interact with PARP-generated poly(ADP-ribose). Through the recruitment of PARP-1, macroH2A1.1 promotes the CBP-mediated acetylation of H2B K12 and K120 which either positively or negatively regulates the expression of macroH2A1-target genes. While macroH2A1-regulated H2B acetylation is a common feature of primary cells, this regulation is typically lost in cancer cells. Consequently, our results provide important insight into macroH2A1.1’s role in cancer suppression.
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Affiliation(s)
- Hongshan Chen
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Yeshiva University, Bronx, New York, USA
| | - Penelope D Ruiz
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Yeshiva University, Bronx, New York, USA
| | - Leonid Novikov
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Yeshiva University, Bronx, New York, USA
| | - Alyssa D Casill
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Yeshiva University, Bronx, New York, USA
| | - Jong Woo Park
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Yeshiva University, Bronx, New York, USA
| | - Matthew J Gamble
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Yeshiva University, Bronx, New York, USA
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15
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Yildirim O, Hung JH, Cedeno RJ, Weng Z, Lengner CJ, Rando OJ. A system for genome-wide histone variant dynamics in ES cells reveals dynamic MacroH2A2 replacement at promoters. PLoS Genet 2014; 10:e1004515. [PMID: 25102063 PMCID: PMC4125097 DOI: 10.1371/journal.pgen.1004515] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2014] [Accepted: 06/03/2014] [Indexed: 12/30/2022] Open
Abstract
Dynamic exchange of a subset of nucleosomes in vivo plays important roles in epigenetic inheritance of chromatin states, chromatin insulator function, chromosome folding, and the maintenance of the pluripotent state of embryonic stem cells. Here, we extend a pulse-chase strategy for carrying out genome-wide measurements of histone dynamics to several histone variants in murine embryonic stem cells and somatic tissues, recapitulating expected characteristics of the well characterized H3.3 histone variant. We extended this system to the less-studied MacroH2A2 variant, commonly described as a "repressive" histone variant whose accumulation in chromatin is thought to fix the epigenetic state of differentiated cells. Unexpectedly, we found that while large intergenic blocks of MacroH2A2 were stably associated with the genome, promoter-associated peaks of MacroH2A2 exhibited relatively rapid exchange dynamics in ES cells, particularly at highly-transcribed genes. Upon differentiation to embryonic fibroblasts, MacroH2A2 was gained primarily in additional long, stably associated blocks across gene-poor regions, while overall turnover at promoters was greatly dampened. Our results reveal unanticipated dynamic behavior of the MacroH2A2 variant in pluripotent cells, and provide a resource for future studies of tissue-specific histone dynamics in vivo.
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Affiliation(s)
- Ozlem Yildirim
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Jui-Hung Hung
- Program in Bioinformatics and Integrative Biology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Ryan J. Cedeno
- Department of Animal Biology, School of Veterinary Medicine and Institute for Regenerative Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Zhiping Weng
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
- Program in Bioinformatics and Integrative Biology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Christopher J. Lengner
- Department of Animal Biology, School of Veterinary Medicine and Institute for Regenerative Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- * E-mail: (CJL); (OJR)
| | - Oliver J. Rando
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
- * E-mail: (CJL); (OJR)
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16
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Peeters SB, Cotton AM, Brown CJ. Variable escape from X-chromosome inactivation: identifying factors that tip the scales towards expression. Bioessays 2014; 36:746-56. [PMID: 24913292 PMCID: PMC4143967 DOI: 10.1002/bies.201400032] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
In humans over 15% of X-linked genes have been shown to ‘escape’ from X-chromosome inactivation (XCI): they continue to be expressed to some extent from the inactive X chromosome. Mono-allelic expression is anticipated within a cell for genes subject to XCI, but random XCI usually results in expression of both alleles in a cell population. Using a study of allelic expression from cultured lymphoblasts and fibroblasts, many of which showed substantial skewing of XCI, we recently reported that the expression of genes lies on a contiunuum between those that are subject to inactivation, and those that escape. We now review allelic expression studies from mouse, and discuss the variability in escape seen in both humans and mice in genic expression levels, between X chromosomes and between tissues. We also discuss current knowledge of the heterochromatic features, DNA elements and three-dimensional topology of the inactive X that contribute to the balance of expression from the otherwise inactive X chromosome.
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Affiliation(s)
- Samantha B Peeters
- Department of Medical Genetics, Molecular Epigenetics Group, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada
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17
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Abstract
Induced pluripotent stem (iPS) cells have provided a rational means of obtaining histo-compatible tissues for ‘patient-specific’ regenerative therapies (Hanna et al. 2010; Yamanaka & Blau 2010). Despite the obvious potential of iPS cell-based therapies, there are certain problems that must be overcome before these therapies can become safe and routine (Ohi et al. 2011; Pera 2011). As an alternative, we have recently explored the possibility of using ‘epigenetic rejuvenation’, where the specialized functions of an old cell are rejuvenated in the absence of any change in its differentiated state (Singh & Zacouto 2010). The mechanism(s) that underpin ‘epigenetic rejuvenation’ are unknown and here we discuss model systems, using key epigenetic modifiers, which might shed light on the processes involved. Epigenetic rejuvenation has advantages over iPS cell techniques that are currently being pursued. First, the genetic and epigenetic abnormalities that arise through the cycle of dedifferentiation of somatic cells to iPS cells followed by redifferentiation of iPS cells into the desired cell type are avoided (Gore et al. 2011; Hussein et al. 2011; Pera 2011): epigenetic rejuvenation does not require passage through the de-/redifferentiation cycle. Second, because the aim of epigenetic rejuvenation is to ensure that the differentiated cell type retains its specialized function it makes redundant the question of transcriptional memory that is inimical to iPS cell-based therapies (Ohi et al. 2011). Third, to produce unrelated cell types using the iPS technology takes a long time, around three weeks, whereas epigenetic rejuvenation of old cells will take only a matter of days. Epigenetic rejuvenation provides the most safe, rapid and cheap route to successful regenerative medicine.
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Affiliation(s)
- Maria Manukyan
- Albert-Ludwigs-Universität Freiburg, BIOSS Centre for Biological Signalling Studies, Zentrum für Biosystemanalyse - ZBSA, Habsburgerstrasse 49, 79104 Freiburg, Germany
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18
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Creppe C, Posavec M, Douet J, Buschbeck M. MacroH2A in stem cells: a story beyond gene repression. Epigenomics 2012; 4:221-7. [PMID: 22449192 DOI: 10.2217/epi.12.8] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The importance of epigenetic mechanisms is most clearly illustrated during early development when a totipotent cell goes through multiple cell fate transitions to form the many different cell types and tissues that constitute the embryo and the adult. The exchange of a canonical H2A histone for the ‘repressive’ macroH2A variant is one of the most striking epigenetic chromatin alterations that can occur at the level of the nucleosome. Here, we discuss recent data on macroH2A in zebrafish and mouse embryos, in embryonic and adult stem cells and also in nuclear reprogramming. We highlight the role of macroH2A in the establishment and maintenance of differentiated states and we discuss its still poorly recognized function in transcriptional activation.
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Affiliation(s)
- Catherine Creppe
- Institute for Predictive & Personalized Medicine of Cancer (IMPPC), Crta. Can Ruti, Cami de les Escoles, 08916 Badalona, Barcelona, Spain
| | - Melanija Posavec
- Institute for Predictive & Personalized Medicine of Cancer (IMPPC), Crta. Can Ruti, Cami de les Escoles, 08916 Badalona, Barcelona, Spain
| | - Julien Douet
- Institute for Predictive & Personalized Medicine of Cancer (IMPPC), Crta. Can Ruti, Cami de les Escoles, 08916 Badalona, Barcelona, Spain
| | - Marcus Buschbeck
- Institute for Predictive & Personalized Medicine of Cancer (IMPPC), Crta. Can Ruti, Cami de les Escoles, 08916 Badalona, Barcelona, Spain
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19
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Berletch JB, Yang F, Xu J, Carrel L, Disteche CM. Genes that escape from X inactivation. Hum Genet 2011; 130:237-45. [PMID: 21614513 PMCID: PMC3136209 DOI: 10.1007/s00439-011-1011-z] [Citation(s) in RCA: 254] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2011] [Accepted: 05/17/2011] [Indexed: 12/30/2022]
Abstract
To achieve a balanced gene expression dosage between males (XY) and females (XX), mammals have evolved a compensatory mechanism to randomly inactivate one of the female X chromosomes. Despite this chromosome-wide silencing, a number of genes escape X inactivation: in women about 15% of X-linked genes are bi-allelically expressed and in mice, about 3%. Expression from the inactive X allele varies from a few percent of that from the active allele to near equal expression. While most genes have a stable inactivation pattern, a subset of genes exhibit tissue-specific differences in escape from X inactivation. Escape genes appear to be protected from the repressive chromatin modifications associated with X inactivation. Differences in the identity and distribution of escape genes between species and tissues suggest a role for these genes in the evolution of sex differences in specific phenotypes. The higher expression of escape genes in females than in males implies that they may have female-specific roles and may be responsible for some of the phenotypes observed in X aneuploidy.
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Affiliation(s)
- Joel B. Berletch
- Department of Pathology, University of Washington School of Medicine, Seattle, WA 98195, USA
| | - Fan Yang
- Department of Pathology, University of Washington School of Medicine, Seattle, WA 98195, USA
| | - Jun Xu
- Department of Biomedical Sciences, Tufts University Cummings School of Veterinary Medicine, North Grafton, MA 01536, USA
| | - Laura Carrel
- Department of Biochemistry and Molecular Biology, Pennsylvania State College of Medicine, Hershey, PA 17033, USA
| | - Christine M. Disteche
- Department of Pathology, University of Washington School of Medicine, Seattle, WA 98195, USA. Department of Medicine, University of Washington School of Medicine, Seattle, WA 98195, USA
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20
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Tanasijevic B, Rasmussen TP. X chromosome inactivation and differentiation occur readily in ES cells doubly-deficient for macroH2A1 and macroH2A2. PLoS One 2011; 6:e21512. [PMID: 21738686 PMCID: PMC3127949 DOI: 10.1371/journal.pone.0021512] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2011] [Accepted: 05/31/2011] [Indexed: 12/29/2022] Open
Abstract
Macrohistones (mH2As) are unusual histone variants found exclusively in vertebrate chromatin. In mice, the H2afy gene encodes two splice variants, mH2A1.1 and mH2A1.2 and a second gene, H2afy2, encodes an additional mH2A2 protein. Both mH2A isoforms have been found enriched on the inactive X chromosome (Xi) in differentiated mammalian female cells, and are incorporated into the chromatin of developmentally-regulated genes. To investigate the functional significance of mH2A isoforms for X chromosome inactivation (XCI), we produced male and female embryonic stem cell (ESC) lines with stably-integrated shRNA constructs that simultaneously target both mH2A1 and mH2A2. Surprisingly, we find that female ESCs deficient for both mH2A1 and mH2A2 readily execute and maintain XCI upon differentiation. Furthermore, male and female mH2A-deficient ESCs proliferate normally under pluripotency culture conditions, and respond to several standard differentiation procedures efficiently. Our results show that XCI can readily proceed with substantially reduced total mH2A content.
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Affiliation(s)
- Borko Tanasijevic
- Center for Regenerative Biology, University of Connecticut, Storrs, Connecticut, United States of America
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, Connecticut, United States of America
| | - Theodore P. Rasmussen
- Center for Regenerative Biology, University of Connecticut, Storrs, Connecticut, United States of America
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, Connecticut, United States of America
- Department of Pharmaceutical Sciences, University of Connecticut, Storrs, Connecticut, United States of America
- * E-mail:
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21
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Evolutionary diversity and developmental regulation of X-chromosome inactivation. Hum Genet 2011; 130:307-27. [PMID: 21687993 PMCID: PMC3132430 DOI: 10.1007/s00439-011-1029-2] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2011] [Accepted: 05/31/2011] [Indexed: 12/26/2022]
Abstract
X-chromosome inactivation (XCI) results in the transcriptional silencing of one X-chromosome in females to attain gene dosage parity between XX female and XY male mammals. Mammals appear to have developed rather diverse strategies to initiate XCI in early development. In placental mammals XCI depends on the regulatory noncoding RNA X-inactive specific transcript (Xist), which is absent in marsupials and monotremes. Surprisingly, even placental mammals show differences in the initiation of XCI in terms of Xist regulation and the timing to acquire dosage compensation. Despite this, all placental mammals achieve chromosome-wide gene silencing at some point in development, and this is maintained by epigenetic marks such as chromatin modifications and DNA methylation. In this review, we will summarise recent findings concerning the events that occur downstream of Xist RNA coating of the inactive X-chromosome (Xi) to ensure its heterochromatinization and the maintenance of the inactive state in the mouse and highlight similarities and differences between mammals.
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22
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Muthurajan UM, McBryant SJ, Lu X, Hansen JC, Luger K. The linker region of macroH2A promotes self-association of nucleosomal arrays. J Biol Chem 2011; 286:23852-64. [PMID: 21532035 PMCID: PMC3129167 DOI: 10.1074/jbc.m111.244871] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
MacroH2A is a histone variant found in higher eukaryotes localized at the inactive X chromosome and is known to maintain heterochromatic regions in the genome. MacroH2A consists of a conserved histone domain and a macro domain connected by a linker region. To understand the contributions of the three domains to chromatin condensation, we incorporated various constructs of macroH2A into defined nucleosomal arrays and analyzed their impact on in vitro chromatin compaction. The folding and oligomerization properties of arrays containing full-length macroH2A (macroH2AFL), macroH2A(1–161) (encompassing the histone domain and linker region), and macroH2A(1–122) (histone domain only) were compared with major-type H2A arrays. Analytical ultracentrifugation and atomic force microscope imaging indicate that macroH2A(1–161)-containing arrays favor condensation under conditions where major-type arrays are nearly fully extended. In contrast, arrays with macroH2AFL exhibit behavior similar to that of major-type arrays. This suggests that the linker region of macroH2A facilitates array condensation and that this behavior is inhibited by the macro domain. Furthermore, chimeric major-type H2A arrays containing the macroH2A linker domain (H2AML) exhibited the same condensation properties as macroH2A(1–161) arrays, thus emphasizing the intriguing behavior of the macroH2A linker region.
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23
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Kreiling JA, Tamamori-Adachi M, Sexton AN, Jeyapalan JC, Munoz-Najar U, Peterson AL, Manivannan J, Rogers ES, Pchelintsev NA, Adams PD, Sedivy JM. Age-associated increase in heterochromatic marks in murine and primate tissues. Aging Cell 2011; 10:292-304. [PMID: 21176091 DOI: 10.1111/j.1474-9726.2010.00666.x] [Citation(s) in RCA: 113] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Chromatin is highly dynamic and subject to extensive remodeling under many physiologic conditions. Changes in chromatin that occur during the aging process are poorly documented and understood in higher organisms, such as mammals. We developed an immunofluorescence assay to quantitatively detect, at the single cell level, changes in the nuclear content of chromatin-associated proteins. We found increased levels of the heterochromatin-associated proteins histone macro H2A (mH2A) and heterochromatin protein 1 beta (HP1β) in human fibroblasts during replicative senescence in culture, and for the first time, an age-associated increase in these heterochromatin marks in several tissues of mice and primates. Mouse lung was characterized by monophasic mH2A expression histograms at both ages, and an increase in mean staining intensity at old age. In the mouse liver, we observed increased age-associated localization of mH2A to regions of pericentromeric heterochromatin. In the skeletal muscle, we found two populations of cells with either low or high mH2A levels. This pattern of expression was similar in mouse and baboon, and showed a clear increase in the proportion of nuclei with high mH2A levels in older animals. The frequencies of cells displaying evidence of increased heterochromatinization are too high to be readily accounted for by replicative or oncogene-induced cellular senescence, and are prominently found in terminally differentiated, postmitotic tissues that are not conventionally thought to be susceptible to senescence. Our findings distinguish specific chromatin states in individual cells of mammalian tissues, and provide a foundation to investigate further the progressive epigenetic changes that occur during aging.
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Kreiling JA, Tamamori-Adachi M, Sexton AN, Jeyapalan JC, Munoz-Najar U, Peterson AL, Manivannan J, Rogers ES, Pchelintsev NA, Adams PD, Sedivy JM. Age-associated increase in heterochromatic marks in murine and primate tissues. Aging Cell 2011. [PMID: 21176091 DOI: 10.1111/j.1474-9726.2010.00666.x.age-associated] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/20/2023] Open
Abstract
Chromatin is highly dynamic and subject to extensive remodeling under many physiologic conditions. Changes in chromatin that occur during the aging process are poorly documented and understood in higher organisms, such as mammals. We developed an immunofluorescence assay to quantitatively detect, at the single cell level, changes in the nuclear content of chromatin-associated proteins. We found increased levels of the heterochromatin-associated proteins histone macro H2A (mH2A) and heterochromatin protein 1 beta (HP1β) in human fibroblasts during replicative senescence in culture, and for the first time, an age-associated increase in these heterochromatin marks in several tissues of mice and primates. Mouse lung was characterized by monophasic mH2A expression histograms at both ages, and an increase in mean staining intensity at old age. In the mouse liver, we observed increased age-associated localization of mH2A to regions of pericentromeric heterochromatin. In the skeletal muscle, we found two populations of cells with either low or high mH2A levels. This pattern of expression was similar in mouse and baboon, and showed a clear increase in the proportion of nuclei with high mH2A levels in older animals. The frequencies of cells displaying evidence of increased heterochromatinization are too high to be readily accounted for by replicative or oncogene-induced cellular senescence, and are prominently found in terminally differentiated, postmitotic tissues that are not conventionally thought to be susceptible to senescence. Our findings distinguish specific chromatin states in individual cells of mammalian tissues, and provide a foundation to investigate further the progressive epigenetic changes that occur during aging.
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Affiliation(s)
- Jill A Kreiling
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, 70 Ship Street, Providence, RI 02903, USA.
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Abstract
Autoimmune diseases appear to have multiple contributing factors including genetics, epigenetics, environmental factors, and aging. The predominance of females among patients with autoimmune diseases suggests possible involvement of the X chromosome and X chromosome inactivation. X chromosome inactivation is an epigenetic event resulting in multiple levels of control for modulation of the expression of X-linked genes in normal female cells such that there remains only one active X chromosome in the cell. The extent of this control is unique among the chromosomes and has the potential for problems when regulation is disrupted. Here we discuss the X chromosome inactivation process and how the X chromosome and X chromosome inactivation may be involved in development of autoimmune disorders.
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Affiliation(s)
- Wesley H Brooks
- Experimental HTS, Drug Discovery, H. Lee Moffitt Cancer Center & Research Institute, Tampa, FL 33612-9416, USA.
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Barzily-Rokni M, Friedman N, Ron-Bigger S, Isaac S, Michlin D, Eden A. Synergism between DNA methylation and macroH2A1 occupancy in epigenetic silencing of the tumor suppressor gene p16(CDKN2A). Nucleic Acids Res 2010; 39:1326-35. [PMID: 21030442 PMCID: PMC3045621 DOI: 10.1093/nar/gkq994] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Promoter hypermethylation and heterochromatinization is a frequent event leading to gene inactivation and tumorigenesis. At the molecular level, inactivation of tumor suppressor genes in cancer has many similarities to the inactive X chromosome in female cells and is defined and maintained by DNA methylation and characteristic histone modifications. In addition, the inactive-X is marked by the histone macroH2A, a variant of H2A with a large non-histone region of unknown function. Studying tumor suppressor genes (TSGs) silenced in cancer cell lines, we find that when active, these promoters are associated with H2A.Z but become enriched for macroH2A1 once silenced. Knockdown of macroH2A1 was not sufficient for reactivation of silenced genes. However, when combined with DNA demethylation, macroH2A1 deficiency significantly enhanced reactivation of the tumor suppressor genes p16, MLH1 and Timp3 and inhibited cell proliferation. Our findings link macroH2A1 to heterochromatin of epigenetically silenced cancer genes and indicate synergism between macroH2A1 and DNA methylation in maintenance of the silenced state.
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Affiliation(s)
- Michal Barzily-Rokni
- Department of Cell & Developmental Biology, Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
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Genome-wide distribution of macroH2A1 histone variants in mouse liver chromatin. Mol Cell Biol 2010; 30:5473-83. [PMID: 20937776 DOI: 10.1128/mcb.00518-10] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Studies of macroH2A histone variants indicate that they have a role in regulating gene expression. To identify direct targets of the macroH2A1 variants, we produced a genome-wide map of the distribution of macroH2A1 nucleosomes in mouse liver chromatin using high-throughput DNA sequencing. Although macroH2A1 nucleosomes are widely distributed across the genome, their local concentration varies over a range of 100-fold or more. The transcribed regions of most active genes are depleted of macroH2A1, often in sharply localized domains that show depletion of 4-fold or more relative to bulk mouse liver chromatin. We used macroH2A1 enrichment to help identify genes that appear to be directly regulated by macroH2A1 in mouse liver. These genes functionally cluster in the area of lipid metabolism. All but one of these genes has increased expression in macroH2A1 knockout mice, indicating that macroH2A1 functions primarily as a repressor in adult liver. This repressor activity is further supported by the substantial and relatively uniform macroH2A1 enrichment along the inactive X chromosome, which averages 4-fold. Genes that escape X inactivation stand out as domains of macroH2A1 depletion. The rarity of such genes indicates that few genes escape X inactivation in mouse liver, in contrast to what has been observed in human cells.
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Araya I, Nardocci G, Morales J, Vera M, Molina A, Alvarez M. MacroH2A subtypes contribute antagonistically to the transcriptional regulation of the ribosomal cistron during seasonal acclimatization of the carp fish. Epigenetics Chromatin 2010; 3:14. [PMID: 20670405 PMCID: PMC2919529 DOI: 10.1186/1756-8935-3-14] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2010] [Accepted: 07/29/2010] [Indexed: 11/18/2022] Open
Abstract
Background Incorporation of histone variants into chromatin is one of the epigenetic mechanisms used for regulation of gene expression. Macro (m)H2A is a histone variant that has two different subtypes in vertebrates: mH2A1 and mH2A2. It is known that mH2A is associated with gene silencing, but recent studies indicate that these mH2A subtypes could contribute more widely to transcriptional regulation. We have previously demonstrated that the gene-reprogramming response mediates adaptation of the carp fish to its environment, and that ribosomal gene transcription is seasonally regulated in carp. However, there have been few studies investigating how epigenetic mechanisms contribute to environmental adaptation and, in particular, to ribosomal cistron regulation. Results In this paper, we report the occurrence of differential incorporation of mH2A subtypes into chromatin during seasonal adaptation in the carp, an event that concurs with opposing transcriptional states. Moreover, we observed that enrichment of mH2A1 in the ribosomal cistron during winter, and conversely, enrichment of mH2A2 during summer. mH2A1 consistently colocalizes with a heterochromatin marker (H3K27me2; histone H3 trimethylated at lysine 27) and mH2A2 with a euchromatin marker (H3K4me3; histone H3 trimethylated at lysine 4). Similar results were found for the L41gene, with enrichment of mH2A in the promoter region. Conclusions We have characterized both mH2A subtypes from carp fish, and evaluated their participation in the regulation of the ribosomal cistron. Our findings indicate that differential incorporation of mH2A subtypes into the ribosome could regulate gene expression during the acclimatization process in carp. Our results reveal differential chromatin incorporation of the mH2A subtypes during the environmental adaptation process, correlating wtih antagonistic transcriptional states in the carp ribosomal cistron.
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Affiliation(s)
- I Araya
- Laboratorio de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Universidad Andrés Bello, Avenida República 217, MIFAB, Santiago, Chile.
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29
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Abstract
A subset of X-linked genes escapes silencing by X inactivation and is expressed from both X chromosomes in mammalian females. Species-specific differences in the identity of these genes have recently been discovered, suggesting a role in the evolution of sex differences. Chromatin analyses have aimed to discover how genes remain expressed within a repressive environment.
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Affiliation(s)
- Joel B Berletch
- Department of Pathology, University of Washington, Seattle, Washington 98195, USA
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30
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Gamble MJ, Frizzell KM, Yang C, Krishnakumar R, Kraus WL. The histone variant macroH2A1 marks repressed autosomal chromatin, but protects a subset of its target genes from silencing. Genes Dev 2009; 24:21-32. [PMID: 20008927 DOI: 10.1101/gad.1876110] [Citation(s) in RCA: 130] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
MacroH2A1 is a histone variant that is enriched on the inactive X chromosome (Xi) in mammals and is postulated to play an important, but unknown, role in the repression of gene expression. Here we show that, although macroH2A1 marks repressed autosomal chromatin, it positively regulates transcription when located in the transcribed regions of a subset of its target genes. We used chromatin immunoprecipitation (ChIP) coupled with tiling microarrays (ChIP-chip) to determine the genomic localization of macroH2A1 in IMR90 human primary lung fibroblasts and MCF-7 breast cancer cells. The patterns of macroH2A1 deposition are largely similar across the autosomes of both cell lines. Our studies revealed a genomic localization pattern unique among histone variants; namely, the occupation by macroH2A1 of large chromatin domains (>500 kb in some cases) that contain repressive chromatin marks (e.g., histone H3 Lys 27 trimethylation). The boundaries of macroH2A1-containing domains tend to occur in promoter-proximal regions. Not all promoters, however, serve as macroH2A1 boundaries; many macroH2A1-containing chromatin domains invade the transcribed regions of genes whose products play key roles in development and cell-cell signaling. Surprisingly, the expression of a subset of these genes is positively regulated by macroH2A1. MacroH2A1 also plays a role in augmenting signal-regulated transcription, specifically for genes responsive to serum starvation. Collectively, our results document an unexpected role for macroH2A1 in the escape from heterochromatin-associated silencing and the enhancement of autosomal gene transcription.
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Affiliation(s)
- Matthew J Gamble
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14853, USA
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31
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The histone variant macroH2A is an epigenetic regulator of key developmental genes. Nat Struct Mol Biol 2009; 16:1074-9. [PMID: 19734898 DOI: 10.1038/nsmb.1665] [Citation(s) in RCA: 147] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2009] [Accepted: 08/07/2009] [Indexed: 01/22/2023]
Abstract
The histone variants macroH2A1 and macroH2A2 are associated with X chromosome inactivation in female mammals. However, the physiological function of macroH2A proteins on autosomes is poorly understood. Microarray-based analysis in human male pluripotent cells uncovered occupancy of both macroH2A variants at many genes encoding key regulators of development and cell fate decisions. On these genes, the presence of macroH2A1+2 is a repressive mark that overlaps locally and functionally with Polycomb repressive complex 2. We demonstrate that macroH2A1+2 contribute to the fine-tuning of temporal activation of HOXA cluster genes during neuronal differentiation. Furthermore, elimination of macroH2A2 function in zebrafish embryos produced severe but specific phenotypes. Taken together, our data demonstrate that macroH2A variants constitute an important epigenetic mark involved in the concerted regulation of gene expression programs during cellular differentiation and vertebrate development.
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32
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The polycomb group protein Bmi1 binds to the herpes simplex virus 1 latent genome and maintains repressive histone marks during latency. J Virol 2009; 83:8173-81. [PMID: 19515780 DOI: 10.1128/jvi.00686-09] [Citation(s) in RCA: 118] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The mechanism by which herpes simplex virus 1 (HSV-1) establishes latency in sensory neurons is largely unknown. Recent studies indicate that epigenetic modifications of the chromatin associated with the latent genome may play a key role in the transcriptional control of lytic genes during latency. In this study, we found both constitutive and facultative types of heterochromatin to be present on the latent HSV-1 genome. Deposition of the facultative marks trimethyl H3K27 and histone variant macroH2A varied at different sites on the genome, whereas the constitutive marker trimethyl H3K9 did not. In addition, we show that in the absence of the latency-associated transcript (LAT), the latent genome shows a dramatic increase in trimethyl H3K27, suggesting that expression of the LAT during latency may act to promote an appropriate heterochromatic state that represses lytic genes but is still poised for reactivation. Due to the presence of the mark trimethyl H3K27, we examined whether Polycomb group proteins, which methylate H3K27, were present on the HSV-1 genome during latency. Our data indicate that Bmi1, a member of the Polycomb repressive complex 1 (PRC1) maintenance complex, associates with specific sites in the genome, with the highest level of enrichment at the LAT enhancer. To our knowledge, these are the first data demonstrating that a virus can repress its gene transcription to enter latency by exploiting the mechanism of Polycomb-mediated repression.
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33
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Abstract
Genomic imprinting results in the expression of genes in a parent-of-origin-dependent manner. The mechanism and developmental consequences of genomic imprinting are most well characterized in mammals, plants, and certain insect species (e.g., sciarid flies and coccid insects). However, researchers have observed imprinting phenomena in species in which imprinting of endogenous genes is not known to exist or to be developmentally essential. In this review, I survey the known mechanisms of imprinting, focusing primarily on examples from mammals, where imprinting is relatively well characterized. Where appropriate, I draw attention to imprinting mechanisms in other organisms to compare and contrast how diverse organisms employ different strategies to perform the same process. I discuss how the various mechanisms come into play in the context of the imprint life cycle. Finally, I speculate why imprinting may be more widely prevalent than previously thought.
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Affiliation(s)
- Ky Sha
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
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34
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Weak but uniform enrichment of the histone variant macroH2A1 along the inactive X chromosome. Mol Cell Biol 2008; 29:150-6. [PMID: 18936163 DOI: 10.1128/mcb.00997-08] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
We studied the enrichment and distribution of the histone variant mH2A1 in the condensed inactive X (Xi) chromosome. By using highly specific antibodies against mH2A1 and stable HEK 293 cell lines expressing either green fluorescent protein (GFP)-mH2A1 or GFP-H2A, we found that the Xi chromosome contains approximately 1.5-fold more mH2A1 than the autosomes. To determine the in vivo distribution of mH2A1 along the X chromosome, we used a native chromatin immunoprecipitation-on-chip technique. DNA isolated from mH2A1-immunoprecipitated nucleosomes from either male or female mouse liver were hybridized to tiling microarrays covering 5 kb around most promoters or the entire X chromosome. The data show that mH2A1 is uniformly distributed across the entire Xi chromosome. Interestingly, a stronger mH2A1 enrichment along the pseudoautosomal X chromosome region was observed in both sexes. Our results indicate a potential role for macroH2A in large-scale chromosome structure and genome stability.
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35
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Allemand E, Batsché E, Muchardt C. Splicing, transcription, and chromatin: a ménage à trois. Curr Opin Genet Dev 2008; 18:145-51. [PMID: 18372167 DOI: 10.1016/j.gde.2008.01.006] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2007] [Revised: 01/16/2008] [Accepted: 01/18/2008] [Indexed: 01/31/2023]
Abstract
Alternative splicing allows for one gene to encode multiple proteins. This mechanism is regulated by dedicated splicing factors. However, recent data have shown that these factors contact the RNA polymerase II as well as transcription factors and chromatin remodeling enzymes present inside the coding region of the gene. These observations favor a model where cotranscriptional splice decisions are assisted by factors recruited at the promoter or by the elongating polymerase. We also suggest that chromatin could function as an RNA-binding matrix displaying the immature transcripts to the spliceosomes.
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Affiliation(s)
- Eric Allemand
- Institut Pasteur, CNRS URA2578, Unité de Régulation Epigénétique, Avenir INSERM, Département de Biologie du Développement, Paris, France
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36
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Abstract
We show that macroH2A1 histone variants are important for repressing the expression of endogenous murine leukemia viruses (MLVs) in mouse liver. Intact MLV proviruses and proviruses with deletions in env were nearly silent in normal mouse liver and showed substantial derepression in macroH2A1 knockout liver. In contrast, MLV proviruses with a deletion in the 5' end of pro-pol were expressed in normal liver and showed relatively low levels of derepression in knockout liver. macroH2A1 nucleosomes were enriched on endogenous MLVs, with the highest enrichment occurring on the 5' end of pro-pol. The absence of macroH2A1 also led to a localized loss of DNA methylation on the 5' ends of MLV proviruses. These results demonstrate that macroH2A1 histones have a significant role in silencing endogenous MLVs in vivo and suggest that specific internal MLV sequences are targeted by a macroH2A1-dependent silencing mechanism.
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37
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Salstrom JL. X-inactivation and the dynamic maintenance of gene silencing. Mol Genet Metab 2007; 92:56-62. [PMID: 17604203 DOI: 10.1016/j.ymgme.2007.05.015] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/10/2007] [Revised: 05/23/2007] [Accepted: 05/23/2007] [Indexed: 01/25/2023]
Abstract
X-inactivation has long been a topic of fascination for educators, researchers, and clinicians alike. From complex patterns of inheritance to phenotypic variation among females with X-linked traits, a myriad of hypothesis and interpretations exist. Once thought to be random yet complete, X-inactivation has proven itself the poster child of the exception rather than the rule. Indeed, patterns of X-inactivation are all too often non-random, and many X-linked genes are capable of escaping X-inactivation. Similarly, X-inactivation is well-known for being stably maintained for life, but some previously inactivated X-linked genes reactivate with increasing age. Moreover, recent papers illustrate that X-inactivation can be challenged in other ways, thereby rendering the stability of X-inactivation compromised. This review describes factors involved in the maintenance of X-inactivation as we know it and discusses these emerging data that suggest a more dynamic model of the maintenance of X-inactivation may be in order.
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Affiliation(s)
- Jennifer L Salstrom
- Department of Human Genetics, David Geffen School of Medicine at UCLA, 6505 Gonda Center-Mail Code 708822, 695 Charles E Young Drive South, Los Angeles, CA 90095-708822, USA.
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38
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Wutz A. Xist function: bridging chromatin and stem cells. Trends Genet 2007; 23:457-64. [PMID: 17681633 DOI: 10.1016/j.tig.2007.07.004] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2007] [Revised: 06/06/2007] [Accepted: 07/18/2007] [Indexed: 11/19/2022]
Abstract
In mammals, dosage compensation is achieved by transcriptional silencing of one of the two female X chromosomes. X inactivation is dynamically regulated in development. The non-coding Xist RNA localizes to the inactive X, initiates gene repression in the early embryo, and later stabilizes the inactive state. Different functions of Xist are observed depending on which epigenetic regulatory pathways are active in a given cell. Because Xist has evolved recently, with the origin of placental mammals, the underlying pathways are also important in regulating developmental control genes. This review emphasizes the opportunity that Xist provides to functionally define epigenetic transitions in development, to understand cell identity, pluripotency and stem cell differentiation.
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Affiliation(s)
- Anton Wutz
- Research Institute of Molecular Pathology, Dr. Bohr-Gasse 7, 1030 Vienna, Austria.
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39
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Adams PD. Remodeling of chromatin structure in senescent cells and its potential impact on tumor suppression and aging. Gene 2007; 397:84-93. [PMID: 17544228 PMCID: PMC2755200 DOI: 10.1016/j.gene.2007.04.020] [Citation(s) in RCA: 127] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2007] [Accepted: 04/09/2007] [Indexed: 11/18/2022]
Abstract
Cellular senescence is an important tumor suppression process, and a possible contributor to tissue aging. Senescence is accompanied by extensive changes in chromatin structure. In particular, many senescent cells accumulate specialized domains of facultative heterochromatin, called Senescence-Associated Heterochromatin Foci (SAHF), which are thought to repress expression of proliferation-promoting genes, thereby contributing to senescence-associated proliferation arrest. This article reviews our current understanding of the structure, assembly and function of these SAHF at a cellular level. The possible contribution of SAHF to tumor suppression and tissue aging is also critically discussed.
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Affiliation(s)
- Peter D Adams
- W446, Fox Chase Cancer Center, Philadelphia, PA 19111, USA.
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40
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Damelin M, Bestor TH. Biological functions of DNA methyltransferase 1 require its methyltransferase activity. Mol Cell Biol 2007; 27:3891-9. [PMID: 17371843 PMCID: PMC1900033 DOI: 10.1128/mcb.00036-07] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
DNA methyltransferase 1 (DNMT1) has been reported to interact with a wide variety of factors and to contain intrinsic transcriptional repressor activity. When a conservative point mutation was introduced at the key catalytic residue, mutant DNMT1 failed to rescue any of the phenotypes of Dnmt1-null embryonic stem (ES) cells, which indicated that the biological functions of DNMT1 are exerted through the methylation of DNA. ES cells that expressed the mutant protein did not survive differentiation. Intracisternal A-particle family retrotransposons were no longer methylated and were transcribed at high levels. The proper localization of DNMT1 depended on normal genomic methylation, and we discuss the implications of this finding for epigenetic dysregulation in cancer.
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Affiliation(s)
- Marc Damelin
- Department of Genetics and Development, College of Physicians and Surgeons of Columbia University, 701 W. 168th Street, New York, NY 10032, USA
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41
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Nusinow DA, Hernández-Muñoz I, Fazzio TG, Shah GM, Kraus WL, Panning B. Poly(ADP-ribose) polymerase 1 is inhibited by a histone H2A variant, MacroH2A, and contributes to silencing of the inactive X chromosome. J Biol Chem 2007; 282:12851-9. [PMID: 17322296 DOI: 10.1074/jbc.m610502200] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Poly(ADP-ribose) polymerase 1 (PARP-1) is a nuclear enzyme that is involved in modulating chromatin structure, regulation of gene expression, and sensing DNA damage. Here, we report that PARP-1 enzymatic activity is inhibited by macroH2A, a vertebrate histone H2A variant that is enriched on facultative heterochromatin. MacroH2A family members have a large C-terminal non-histone domain (NHD) and H2A-like histone domain. MacroH2A1.2 and PARP-1 interact in vivo and in vitro via the NHD. The NHD of each macroH2A family member was sufficient to inhibit PARP-1 enzymatic activity in vitro. The NHD of macroH2A1.2 was a mixed inhibitor of PARP-1 catalytic activity, with affects on both catalytic activity and the substrate binding affinity of PARP-1. Depletion of PARP-1 by RNA interference caused reactivation of a reporter gene on the inactive X chromosome, demonstrating that PARP-1 participates in the maintenance of silencing. These results suggest that one function of macroH2A in gene silencing is to inhibit PARP-1 enzymatic activity, and this may affect PARP-1 association with chromatin.
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Affiliation(s)
- Dmitri A Nusinow
- Department of Biochemistry and Biophysics, University of California, San Francisco, California 94158, USA
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42
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Changolkar LN, Costanzi C, Leu NA, Chen D, McLaughlin KJ, Pehrson JR. Developmental changes in histone macroH2A1-mediated gene regulation. Mol Cell Biol 2007; 27:2758-64. [PMID: 17242180 PMCID: PMC1899912 DOI: 10.1128/mcb.02334-06] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
macroH2A histone variants have been implicated to function in gene silencing by several studies, including ones showing a preferential association of macroH2A on the inactive X chromosome. To examine macroH2A function in vivo, we knocked out macroH2A1. macroH2A1 knockout mice are viable and fertile. A broad screen of liver gene expression showed no evidence of defects in X inactivation but did identify genes that have increased expression levels in macroH2A1 knockouts. macroH2A1-containing nucleosomes are enriched on the coding and/or upstream regions of these genes, suggesting that their increased expression levels are a direct effect of the absence of macroH2A1. The concentrations of macroH2A1 nucleosomes on these genes are low in the livers of newborn mice, and the macroH2A1 knockout had little effect on the expression levels of these genes in newborn liver. Our results indicate that an increase in liver macroH2A1 during the transition from newborn to young-adult status contributes to a decrease in the expression levels of these genes. These genes cluster in the area of lipid metabolism, and we observed metabolic effects in macroH2A1 knockouts. Our results indicate that the function of macroH2A1 histones is not restricted to gene silencing but also involves fine tuning the expression of specific genes.
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Affiliation(s)
- Lakshmi N Changolkar
- Department of Animal Biology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
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Valley CM, Pertz LM, Balakumaran BS, Willard HF. Chromosome-wide, allele-specific analysis of the histone code on the human X chromosome. Hum Mol Genet 2006; 15:2335-47. [PMID: 16787966 DOI: 10.1093/hmg/ddl159] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Variation in the composition of chromatin has been proposed to generate a 'histone code' that epigenetically regulates gene expression in a variety of eukaryotic systems. As a result of the process of X chromosome inactivation, chromatinon the mammalian inactive X chromosome (Xi) is marked by several modifications, including histone hypoacetylation, trimethylation of lysine 9 on histone H3 (H3TrimK9) and substitution of core histone H2A with the histone variant MacroH2A. H3TrimK9 is a well-studied marker for heterochromatin in many organisms, but the distribution and function of MacroH2A are less clear. Cytologically, the Xi in human cells comprises alternating and largely non-overlapping approximately 10-15 Mb domains marked by MacroH2A and H3TrimK9. To examine the genomic deposition of MacroH2A, H3TrimK9 and acetylated histone H4 modifications on the Xi at higher resolution, we used chromatin immunoprecipitation in combination with a SNP-based assay to distinguish the Xi and active X (Xa) in a diploid female cell line and to determine quantitatively the relative enrichment of these histone code elements on the Xi relative to the Xa. Although we found a majority of sites were enriched for either MacroH2A or H3TrimK9 in a manner consistent with the cytological appearance of the Xi, a range of different histone code types were detected at different sites along the X. These findings suggest that the nature of the heterochromatin histone code associated with X inactivation may be more heterogeneous than previously thought and imply that gene silencing can be achieved by a variety of different epigenetic mechanisms whose genomic, evolutionary or developmental basis is now amenable to investigation.
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Affiliation(s)
- Cory M Valley
- Institute for Genome Sciences & Policy, Duke University, Durham, NC 27708, USA
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