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Dakal TC, Dhabhai B, Pant A, Moar K, Chaudhary K, Yadav V, Ranga V, Sharma NK, Kumar A, Maurya PK, Maciaczyk J, Schmidt‐Wolf IGH, Sharma A. Oncogenes and tumor suppressor genes: functions and roles in cancers. MedComm (Beijing) 2024; 5:e582. [PMID: 38827026 PMCID: PMC11141506 DOI: 10.1002/mco2.582] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Revised: 04/21/2024] [Accepted: 04/26/2024] [Indexed: 06/04/2024] Open
Abstract
Cancer, being the most formidable ailment, has had a profound impact on the human health. The disease is primarily associated with genetic mutations that impact oncogenes and tumor suppressor genes (TSGs). Recently, growing evidence have shown that X-linked TSGs have specific role in cancer progression and metastasis as well. Interestingly, our genome harbors around substantial portion of genes that function as tumor suppressors, and the X chromosome alone harbors a considerable number of TSGs. The scenario becomes even more compelling as X-linked TSGs are adaptive to key epigenetic processes such as X chromosome inactivation. Therefore, delineating the new paradigm related to X-linked TSGs, for instance, their crosstalk with autosome and involvement in cancer initiation, progression, and metastasis becomes utmost importance. Considering this, herein, we present a comprehensive discussion of X-linked TSG dysregulation in various cancers as a consequence of genetic variations and epigenetic alterations. In addition, the dynamic role of X-linked TSGs in sex chromosome-autosome crosstalk in cancer genome remodeling is being explored thoroughly. Besides, the functional roles of ncRNAs, role of X-linked TSG in immunomodulation and in gender-based cancer disparities has also been highlighted. Overall, the focal idea of the present article is to recapitulate the findings on X-linked TSG regulation in the cancer landscape and to redefine their role toward improving cancer treatment strategies.
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Affiliation(s)
- Tikam Chand Dakal
- Department of BiotechnologyGenome and Computational Biology LabMohanlal Sukhadia UniversityUdaipurRajasthanIndia
| | - Bhanupriya Dhabhai
- Department of BiotechnologyGenome and Computational Biology LabMohanlal Sukhadia UniversityUdaipurRajasthanIndia
| | - Anuja Pant
- Department of BiochemistryCentral University of HaryanaMahendergarhHaryanaIndia
| | - Kareena Moar
- Department of BiochemistryCentral University of HaryanaMahendergarhHaryanaIndia
| | - Kanika Chaudhary
- School of Life Sciences. Jawaharlal Nehru UniversityNew DelhiIndia
| | - Vikas Yadav
- School of Life Sciences. Jawaharlal Nehru UniversityNew DelhiIndia
| | - Vipin Ranga
- Dearptment of Agricultural BiotechnologyDBT‐NECAB, Assam Agricultural UniversityJorhatAssamIndia
| | | | - Abhishek Kumar
- Manipal Academy of Higher EducationManipalKarnatakaIndia
- Institute of Bioinformatics, International Technology ParkBangaloreIndia
| | - Pawan Kumar Maurya
- Department of BiochemistryCentral University of HaryanaMahendergarhHaryanaIndia
| | - Jarek Maciaczyk
- Department of Stereotactic and Functional NeurosurgeryUniversity Hospital of BonnBonnGermany
| | - Ingo G. H. Schmidt‐Wolf
- Department of Integrated OncologyCenter for Integrated Oncology (CIO)University Hospital BonnBonnGermany
| | - Amit Sharma
- Department of Stereotactic and Functional NeurosurgeryUniversity Hospital of BonnBonnGermany
- Department of Integrated OncologyCenter for Integrated Oncology (CIO)University Hospital BonnBonnGermany
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2
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Song QH, Zhao KX, Huang S, Chen T, He L. Escape from X-chromosome inactivation and sex differences in Alzheimer's disease. Rev Neurosci 2024; 35:341-354. [PMID: 38157427 DOI: 10.1515/revneuro-2023-0108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Accepted: 11/24/2023] [Indexed: 01/03/2024]
Abstract
Sex differences exist in the onset and progression of Alzheimer's disease. Globally, women have a higher prevalence, while men with Alzheimer's disease experience earlier mortality and more pronounced cognitive decline than women. The cause of sex differences in Alzheimer's disease remains unclear. Accumulating evidence suggests the potential role of X-linked genetic factors in the sex difference of Alzheimer's disease (AD). During embryogenesis, a remarkable process known as X-chromosome inactivation (XCI) occurs in females, leading to one of the X chromosomes undergoing transcriptional inactivation, which balances the effects of two X chromosomes in females. Nevertheless, certain genes exceptionally escape from XCI, which provides a basis for dual expression dosage of specific genes in females. Based on recent research findings, we explore key escape genes and their potential therapeutic use associated with Alzheimer's disease. Also, we discuss their possible role in driving the sex differences in Alzheimer's disease. This will provide new perspectives for precision medicine and gender-specific treatment of AD.
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Affiliation(s)
- Qing-Hua Song
- Department of Pharmacology, China Pharmaceutical University, No. 24 Tong Jia Xiang, Nanjing 210009, Jiangsu Province, China
| | - Ke-Xuan Zhao
- Department of Pharmacology, China Pharmaceutical University, No. 24 Tong Jia Xiang, Nanjing 210009, Jiangsu Province, China
| | - Shuai Huang
- Department of Pharmacology, China Pharmaceutical University, No. 24 Tong Jia Xiang, Nanjing 210009, Jiangsu Province, China
| | - Tong Chen
- Department of Pharmacology, China Pharmaceutical University, No. 24 Tong Jia Xiang, Nanjing 210009, Jiangsu Province, China
| | - Ling He
- Department of Pharmacology, China Pharmaceutical University, No. 24 Tong Jia Xiang, Nanjing 210009, Jiangsu Province, China
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3
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Cao W, Douglas KC, Samollow PB, VandeBerg JL, Wang X, Clark AG. Origin and Evolution of Marsupial-specific Imprinting Clusters Through Lineage-specific Gene Duplications and Acquisition of Promoter Differential Methylation. Mol Biol Evol 2023; 40:msad022. [PMID: 36721950 PMCID: PMC9937046 DOI: 10.1093/molbev/msad022] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Revised: 01/08/2023] [Accepted: 01/25/2023] [Indexed: 02/02/2023] Open
Abstract
Genomic imprinting is a parent-of-origin-specific expression phenomenon that plays fundamental roles in many biological processes. In animals, imprinting is only observed in therian mammals, with ∼200 imprinted genes known in humans and mice. The imprinting pattern in marsupials has been minimally investigated by examining orthologs to known eutherian imprinted genes. To identify marsupial-specific imprinting in an unbiased way, we performed RNA-seq studies on samples of fetal brain and placenta from the reciprocal cross progeny of two laboratory opossum stocks. We inferred allele-specific expression for >3,000 expressed genes and discovered/validated 13 imprinted genes, including three previously known imprinted genes, Igf2r, Peg10, and H19. We estimate that marsupials imprint ∼60 autosomal genes, which is a much smaller set compared with eutherians. Among the nine novel imprinted genes, three noncoding RNAs have no known homologs in eutherian mammals, while the remaining genes have important functions in pluripotency, transcription regulation, nucleolar homeostasis, and neural differentiation. Methylation analyses at promoter CpG islands revealed differentially methylated regions in five of these marsupial-specific imprinted genes, suggesting that differential methylation is a common mechanism in the epigenetic regulation of marsupial imprinting. Clustering and co-regulation were observed at marsupial imprinting loci Pou5f3-Npdc1 and Nkrfl-Ipncr2, but eutherian-type multi-gene imprinting clusters were not detected. Also differing from eutherian mammals, the brain and placenta imprinting profiles are remarkably similar in opossums, presumably due to the shared origin of these organs from the trophectoderm. Our results contribute to a fuller understanding of the origin, evolution, and mechanisms of genomic imprinting in therian mammals.
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Affiliation(s)
- Wenqi Cao
- Department of Pathobiology, College of Veterinary Medicine, Auburn University, Auburn, AL, USA
- Innovation, and Commerce, Alabama Agricultural Experiment Station, Auburn University Center for Advanced Science, Auburn, AL, USA
| | - Kory C Douglas
- Department of Veterinary Integrative Biosciences, School of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX, USA
| | - Paul B Samollow
- Department of Veterinary Integrative Biosciences, School of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX, USA
| | - John L VandeBerg
- South Texas Diabetes and Obesity Institute and Department of Human Genetics, School of Medicine, The University of Texas Rio Grande Valley, Brownsville, TX, USA
| | - Xu Wang
- Department of Pathobiology, College of Veterinary Medicine, Auburn University, Auburn, AL, USA
- Innovation, and Commerce, Alabama Agricultural Experiment Station, Auburn University Center for Advanced Science, Auburn, AL, USA
- Scott-Ritchey Research Center, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, USA
- HudsonAlpha Institute for Biotechnology, Huntsville, AL, USA
| | - Andrew G Clark
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, USA
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4
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Epigenetic regulation of fetal brain development in pig. Gene 2022; 844:146823. [PMID: 35988784 DOI: 10.1016/j.gene.2022.146823] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Revised: 07/27/2022] [Accepted: 08/15/2022] [Indexed: 02/01/2023]
Abstract
How fetal brain development is regulated at the molecular level is not well understood. Due to ethical challenges associated with research on the human fetus, large animals particularly pigs are increasingly used to study development and disorders of fetal brain. The pig fetal brain grows rapidly during the last ∼ 50 days before birth which is around day 60 (d60) of pig gestation. But what regulates the onset of accelerated growth of the brain is unknown. The current study tests the hypothesis that epigenetic alteration around d60 is involved in the onset of rapid growth of fetal brain of pig. To test this hypothesis, DNA methylation changes of fetal brain was assessed in a genome-wide manner by Enzymatic Methyl-seq (EM-seq) during two gestational periods (GP): d45 vs. d60 (GP1) and d60 vs. d90 (GP2). The cytosine-guanine (CpG) methylation data was analyzed in an integrative manner with the RNA-seq data generated from the same brain samples from our earlier study. A neural network based modeling approach was implemented to learn changes in methylation patterns of the differentially expressed genes, and then predict methylations of the brain in a genome-wide manner during rapid growth. This approach identified specific methylations that changed in a mutually informative manner during rapid growth of the fetal brain. These methylations were significantly overrepresented in specific genic as well as intergenic features including CpG islands, introns, and untranslated regions. In addition, sex-bias methylations of known single nucleotide polymorphic sites were also identified in the fetal brain ide during rapid growth.
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5
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Samanta MK, Gayen S, Harris C, Maclary E, Murata-Nakamura Y, Malcore RM, Porter RS, Garay PM, Vallianatos CN, Samollow PB, Iwase S, Kalantry S. Activation of Xist by an evolutionarily conserved function of KDM5C demethylase. Nat Commun 2022; 13:2602. [PMID: 35545632 PMCID: PMC9095838 DOI: 10.1038/s41467-022-30352-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Accepted: 04/26/2022] [Indexed: 12/03/2022] Open
Abstract
XX female and XY male therian mammals equalize X-linked gene expression through the mitotically-stable transcriptional inactivation of one of the two X chromosomes in female somatic cells. Here, we describe an essential function of the X-linked homolog of an ancestral X-Y gene pair, Kdm5c-Kdm5d, in the expression of Xist lncRNA, which is required for stable X-inactivation. Ablation of Kdm5c function in females results in a significant reduction in Xist RNA expression. Kdm5c encodes a demethylase that enhances Xist expression by converting histone H3K4me2/3 modifications into H3K4me1. Ectopic expression of mouse and human KDM5C, but not the Y-linked homolog KDM5D, induces Xist in male mouse embryonic stem cells (mESCs). Similarly, marsupial (opossum) Kdm5c but not Kdm5d also upregulates Xist in male mESCs, despite marsupials lacking Xist, suggesting that the KDM5C function that activates Xist in eutherians is strongly conserved and predates the divergence of eutherian and metatherian mammals. In support, prototherian (platypus) Kdm5c also induces Xist in male mESCs. Together, our data suggest that eutherian mammals co-opted the ancestral demethylase KDM5C during sex chromosome evolution to upregulate Xist for the female-specific induction of X-inactivation.
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Affiliation(s)
- Milan Kumar Samanta
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, MI, 48109-5618, USA
| | - Srimonta Gayen
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, MI, 48109-5618, USA
- Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bangalore, Karnataka, 560012, India
| | - Clair Harris
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, MI, 48109-5618, USA
| | - Emily Maclary
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, MI, 48109-5618, USA
- Department of Biology, University of Utah, Salt Lake City, UT, 84112, USA
| | - Yumie Murata-Nakamura
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, MI, 48109-5618, USA
| | - Rebecca M Malcore
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, MI, 48109-5618, USA
| | - Robert S Porter
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, MI, 48109-5618, USA
| | - Patricia M Garay
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, MI, 48109-5618, USA
- Neuroscience Graduate Program, University of Michigan Medical School, Ann Arbor, MI, 48109-5618, USA
| | - Christina N Vallianatos
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, MI, 48109-5618, USA
| | - Paul B Samollow
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX, 77843-4458, USA
| | - Shigeki Iwase
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, MI, 48109-5618, USA
- Neuroscience Graduate Program, University of Michigan Medical School, Ann Arbor, MI, 48109-5618, USA
| | - Sundeep Kalantry
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, MI, 48109-5618, USA.
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6
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Mechanisms of Choice in X-Chromosome Inactivation. Cells 2022; 11:cells11030535. [PMID: 35159344 PMCID: PMC8833938 DOI: 10.3390/cells11030535] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 01/30/2022] [Accepted: 01/31/2022] [Indexed: 12/04/2022] Open
Abstract
Early in development, placental and marsupial mammals harbouring at least two X chromosomes per nucleus are faced with a choice that affects the rest of their lives: which of those X chromosomes to transcriptionally inactivate. This choice underlies phenotypical diversity in the composition of tissues and organs and in their response to the environment, and can determine whether an individual will be healthy or affected by an X-linked disease. Here, we review our current understanding of the process of choice during X-chromosome inactivation and its implications, focusing on the strategies evolved by different mammalian lineages and on the known and unknown molecular mechanisms and players involved.
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7
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Xiong X, Samollow PB, Cao W, Metz R, Zhang C, Leandro AC, VandeBerg JL, Wang X. Genetic and genomic architecture in eight strains of the laboratory opossum Monodelphis domestica. G3-GENES GENOMES GENETICS 2021; 12:6423994. [PMID: 34751383 PMCID: PMC8728031 DOI: 10.1093/g3journal/jkab389] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Accepted: 10/24/2021] [Indexed: 11/21/2022]
Abstract
The gray short-tailed opossum (Monodelphis domestica) is an established laboratory-bred marsupial model for biomedical research. It is a critical species for comparative genomics research, providing the pivotal phylogenetic outgroup for studies of derived vs ancestral states of genomic/epigenomic characteristics for eutherian mammal lineages. To characterize the current genetic profile of this laboratory marsupial, we examined 79 individuals from eight established laboratory strains. Double digest restriction site-associated DNA sequencing and whole-genome resequencing experiments were performed to investigate the genetic architecture in these strains. A total of 66,640 high-quality single nucleotide polymorphisms (SNPs) were identified. We analyzed SNP density, average heterozygosity, nucleotide diversity, and population differentiation parameter Fst within and between the eight strains. Principal component and population structure analysis clearly resolve the strains at the level of their ancestral founder populations, and the genetic architecture of these strains correctly reflects their breeding history. We confirmed the successful establishment of the first inbred laboratory opossum strain LSD (inbreeding coefficient F > 0.99) and a nearly inbred strain FD2M1 (0.98 < F < 0.99), each derived from a different ancestral background. These strains are suitable for various experimental protocols requiring controlled genetic backgrounds and for intercrosses and backcrosses that can generate offspring with informative SNPs for studying a variety of genetic and epigenetic processes. Together with recent advances in reproductive manipulation and CRISPR/Cas9 techniques for Monodelphis domestica, the existence of distinctive inbred strains will enable genome editing on different genetic backgrounds, greatly expanding the utility of this marsupial model for biomedical research.
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Affiliation(s)
- Xiao Xiong
- Department of Pathobiology, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, USA.,School of Life Sciences and Technology, Tongji University, Shanghai 200092, China
| | - Paul B Samollow
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA
| | - Wenqi Cao
- Department of Pathobiology, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, USA
| | - Richard Metz
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA
| | - Chao Zhang
- Department of Plastic and Reconstructive Surgery, Shanghai Ninth People's Hospital, Shanghai Institute of Precision Medicine, Shanghai JiaoTong University School of Medicine, Shanghai 200240, China
| | - Ana C Leandro
- South Texas Diabetes and Obesity Institute and Department of Human Genetics, School of Medicine, The University of Texas Rio Grande Valley, Brownsville, TX 78520, USA
| | - John L VandeBerg
- South Texas Diabetes and Obesity Institute and Department of Human Genetics, School of Medicine, The University of Texas Rio Grande Valley, Brownsville, TX 78520, USA
| | - Xu Wang
- Department of Pathobiology, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, USA.,Alabama Agricultural Experiment Station, Auburn, AL 36849, USA.,HudsonAlpha Institute for Biotechnology, Huntsville, AL 35806, USA
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8
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Trotman JB, Braceros KCA, Cherney RE, Murvin MM, Calabrese JM. The control of polycomb repressive complexes by long noncoding RNAs. WILEY INTERDISCIPLINARY REVIEWS. RNA 2021; 12:e1657. [PMID: 33861025 PMCID: PMC8500928 DOI: 10.1002/wrna.1657] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 01/12/2021] [Accepted: 03/19/2021] [Indexed: 02/06/2023]
Abstract
The polycomb repressive complexes 1 and 2 (PRCs; PRC1 and PRC2) are conserved histone-modifying enzymes that often function cooperatively to repress gene expression. The PRCs are regulated by long noncoding RNAs (lncRNAs) in complex ways. On the one hand, specific lncRNAs cause the PRCs to engage with chromatin and repress gene expression over genomic regions that can span megabases. On the other hand, the PRCs bind RNA with seemingly little sequence specificity, and at least in the case of PRC2, direct RNA-binding has the effect of inhibiting the enzyme. Thus, some RNAs appear to promote PRC activity, while others may inhibit it. The reasons behind this apparent dichotomy are unclear. The most potent PRC-activating lncRNAs associate with chromatin and are predominantly unspliced or harbor unusually long exons. Emerging data imply that these lncRNAs promote PRC activity through internal RNA sequence elements that arise and disappear rapidly in evolutionary time. These sequence elements may function by interacting with common subsets of RNA-binding proteins that recruit or stabilize PRCs on chromatin. This article is categorized under: RNA Interactions with Proteins and Other Molecules > Protein-RNA Recognition RNA Interactions with Proteins and Other Molecules > RNA-Protein Complexes RNA Interactions with Proteins and Other Molecules > Protein-RNA Interactions: Functional Implications.
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Affiliation(s)
- Jackson B. Trotman
- Department of Pharmacology and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Keean C. A. Braceros
- Department of Pharmacology and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
- Curriculum in Mechanistic, Interdisciplinary Studies of Biological Systems, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Rachel E. Cherney
- Department of Pharmacology and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - McKenzie M. Murvin
- Department of Pharmacology and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - J. Mauro Calabrese
- Department of Pharmacology and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
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9
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Cook LE, Newton AH, Hipsley CA, Pask AJ. Postnatal development in a marsupial model, the fat-tailed dunnart (Sminthopsis crassicaudata; Dasyuromorphia: Dasyuridae). Commun Biol 2021; 4:1028. [PMID: 34475507 PMCID: PMC8413461 DOI: 10.1038/s42003-021-02506-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Accepted: 07/29/2021] [Indexed: 02/07/2023] Open
Abstract
Marsupials exhibit unique biological features that provide fascinating insights into many aspects of mammalian development. These include their distinctive mode of reproduction, altricial stage at birth, and the associated heterochrony that is required for their crawl to the pouch and teat attachment. Marsupials are also an invaluable resource for mammalian comparative biology, forming a distinct lineage from the extant placental and egg-laying monotreme mammals. Despite their unique biology, marsupial resources are lagging behind those available for placentals. The fat-tailed dunnart (Sminthopsis crassicaudata) is a laboratory based marsupial model, with simple and robust husbandry requirements and a short reproductive cycle making it amenable to experimental manipulations. Here we present a detailed staging series for the fat-tailed dunnart, focusing on their accelerated development of the forelimbs and jaws. This study provides the first skeletal developmental series on S. crassicaudata and provides a fundamental resource for future studies exploring mammalian diversification, development and evolution.
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Affiliation(s)
- Laura E Cook
- School of Biosciences, University of Melbourne, Parkville, VIC, Australia
| | - Axel H Newton
- Department of Anatomy and Developmental Biology, Monash University, Clayton, VIC, Australia
| | - Christy A Hipsley
- School of Biosciences, University of Melbourne, Parkville, VIC, Australia
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
- Department of Sciences, Museums Victoria, Carlton, VIC, Australia
| | - Andrew J Pask
- School of Biosciences, University of Melbourne, Parkville, VIC, Australia.
- Department of Sciences, Museums Victoria, Carlton, VIC, Australia.
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10
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Ingles ED, Deakin JE. Telomeres, species differences, and unusual telomeres in vertebrates: presenting challenges and opportunities to understanding telomere dynamics. AIMS GENETICS 2021. [DOI: 10.3934/genet.2016.1.1] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
AbstractThere has been increasing interest in the use of telomeres as biomarkers of stress, cellular ageing and life-histories. However, the telomere landscape is a diverse feature, with noticeable differences between species, a fact which is highlighted by the unusual telomeres of various vertebrate organisms. We broadly review differences in telomere dynamics among vertebrates, and emphasize the need to understand more about telomere processes and trends across species. As part of these species differences, we review unusual telomeres in vertebrates. This includes mega-telomeres, which are present across a diverse set of organisms, but also focusing on the unusual telomeres traits of marsupials and monotremes, which have seen little to no prior discussion, yet uniquely stand out from other unusual telomere features discovered thus far. Due to the presence of at least two unique telomere features in the marsupial family Dasyuridae, as well as to the presence of physiological strategies semelparity and torpor, which have implications for telomere life-histories in these species, we suggest that this family has a very large potential to uncover novel information on telomere evolution and dynamics.
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Affiliation(s)
- Emory D. Ingles
- Institute of Applied Ecology, University of Canberra, Canberra, ACT 2601, Australia
| | - Janine E. Deakin
- Institute of Applied Ecology, University of Canberra, Canberra, ACT 2601, Australia
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11
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Singh D, Sun D, King AG, Alquezar-Planas DE, Johnson RN, Alvarez-Ponce D, Yi SV. Koala methylomes reveal divergent and conserved DNA methylation signatures of X chromosome regulation. Proc Biol Sci 2021; 288:20202244. [PMID: 33622136 PMCID: PMC7934952 DOI: 10.1098/rspb.2020.2244] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
X chromosome inactivation (XCI) mediated by differential DNA methylation between sexes is an iconic example of epigenetic regulation. Although XCI is shared between eutherians and marsupials, the role of DNA methylation in marsupial XCI remains contested. Here, we examine genome-wide signatures of DNA methylation across fives tissues from a male and female koala (Phascolarctos cinereus), and present the first whole-genome, multi-tissue marsupial ‘methylome atlas’. Using these novel data, we elucidate divergent versus common features of representative marsupial and eutherian DNA methylation. First, tissue-specific differential DNA methylation in koalas primarily occurs in gene bodies. Second, females show significant global reduction (hypomethylation) of X chromosome DNA methylation compared to males. We show that this pattern is also observed in eutherians. Third, on average, promoter DNA methylation shows little difference between male and female koala X chromosomes, a pattern distinct from that of eutherians. Fourth, the sex-specific DNA methylation landscape upstream of Rsx, the primary lncRNA associated with marsupial XCI, is consistent with the epigenetic regulation of female-specific (and presumably inactive X chromosome-specific) expression. Finally, we use the prominent female X chromosome hypomethylation and classify 98 previously unplaced scaffolds as X-linked, contributing an additional 14.6 Mb (21.5%) to genomic data annotated as the koala X chromosome. Our work demonstrates evolutionarily divergent pathways leading to functionally conserved patterns of XCI in two deep branches of mammals.
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Affiliation(s)
- Devika Singh
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA
| | - Dan Sun
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA
| | - Andrew G King
- Australian Museum Research Institute, Australian Museum, Sydney, New South Wales, Australia
| | | | - Rebecca N Johnson
- Australian Museum Research Institute, Australian Museum, Sydney, New South Wales, Australia.,National Museum of Natural History, Smithsonian Institution, Washington, DC, USA
| | | | - Soojin V Yi
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA
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12
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Zhang X, Pavlicev M, Jones HN, Muglia LJ. Eutherian-Specific Gene TRIML2 Attenuates Inflammation in the Evolution of Placentation. Mol Biol Evol 2020; 37:507-523. [PMID: 31633784 PMCID: PMC6993854 DOI: 10.1093/molbev/msz238] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Evolution of highly invasive placentation in the stem lineage of eutherians and subsequent extension of pregnancy set eutherians apart from other mammals, that is, marsupials with short-lived placentas, and oviparous monotremes. Recent studies suggest that eutherian implantation evolved from marsupial attachment reaction, an inflammatory process induced by the direct contact of fetal placenta with maternal endometrium after the breakdown of the shell coat, and shortly before the onset of parturition. Unique to eutherians, a dramatic downregulation of inflammation after implantation prevents the onset of premature parturition, and is critical for the maintenance of gestation. This downregulation likely involved evolutionary changes on maternal as well as fetal/placental side. Tripartite-motif family-like2 (TRIML2) only exists in eutherian genomes and shows preferential expression in preimplantation embryos, and trophoblast-derived structures, such as chorion and placental disc. Comparative genomic evidence supports that TRIML2 originated from a gene duplication event in the stem lineage of Eutheria that also gave rise to eutherian TRIML1. Compared with TRIML1, TRIML2 lost the catalytic RING domain of E3 ligase. However, only TRIML2 is induced in human choriocarcinoma cell line JEG3 with poly(I:C) treatment to simulate inflammation during viral infection. Its knockdown increases the production of proinflammatory cytokines and reduces trophoblast survival during poly(I:C) stimulation, while its overexpression reduces proinflammatory cytokine production, supporting TRIML2’s role as a regulatory inhibitor of the inflammatory pathways in trophoblasts. TRIML2’s potential virus-interacting PRY/SPRY domain shows significant signature of selection, suggesting its contribution to the evolution of eutherian-specific inflammation regulation during placentation.
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Affiliation(s)
- Xuzhe Zhang
- Division of Human Genetics, Center for Prevention of Preterm Birth, Perinatal Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, OH.,Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH.,March of Dimes Prematurity Research Center Ohio Collaborative, Cincinnati, OH
| | - Mihaela Pavlicev
- Division of Human Genetics, Center for Prevention of Preterm Birth, Perinatal Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, OH.,Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH.,March of Dimes Prematurity Research Center Ohio Collaborative, Cincinnati, OH
| | - Helen N Jones
- Division of Pediatric Surgery, Cincinnati Children's Hospital Medical Center, Cincinnati, OH.,Department of Surgery, University of Cincinnati College of Medicine, Cincinnati, OH
| | - Louis J Muglia
- Division of Human Genetics, Center for Prevention of Preterm Birth, Perinatal Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, OH.,Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH.,March of Dimes Prematurity Research Center Ohio Collaborative, Cincinnati, OH
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13
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Mahadevaiah SK, Sangrithi MN, Hirota T, Turner JMA. A single-cell transcriptome atlas of marsupial embryogenesis and X inactivation. Nature 2020; 586:612-617. [PMID: 32814901 DOI: 10.1038/s41586-020-2629-6] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Accepted: 05/20/2020] [Indexed: 11/09/2022]
Abstract
Single-cell RNA sequencing of embryos can resolve the transcriptional landscape of development at unprecedented resolution. To date, single-cell RNA-sequencing studies of mammalian embryos have focused exclusively on eutherian species. Analysis of mammalian outgroups has the potential to identify deeply conserved lineage specification and pluripotency factors, and can extend our understanding of X dosage compensation. Metatherian (marsupial) mammals diverged from eutherians around 160 million years ago. They exhibit distinctive developmental features, including late implantation1 and imprinted X chromosome inactivation2, which is associated with expression of the XIST-like noncoding RNA RSX3. Here we perform a single-cell RNA-sequencing analysis of embryogenesis and X chromosome inactivation in a marsupial, the grey short-tailed opossum (Monodelphis domestica). We resolve the developmental trajectory and transcriptional signatures of the epiblast, primitive endoderm and trophectoderm, and identify deeply conserved lineage-specific markers that pre-date the eutherian-marsupial divergence. RSX coating and inactivation of the X chromosome occurs early and rapidly. This observation supports the hypothesis that-in organisms with early X chromosome inactivation-imprinted X chromosome inactivation prevents biallelic X silencing. We identify XSR, an RSX antisense transcript expressed from the active X chromosome, as a candidate for the regulator of imprinted X chromosome inactivation. Our datasets provide insights into the evolution of mammalian embryogenesis and X dosage compensation.
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Affiliation(s)
| | - Mahesh N Sangrithi
- Division of Obstetrics and Gynaecology, KK Women's and Children's Hospital, Singapore, Singapore.,Duke-NUS Graduate Medical School, Singapore, Singapore
| | - Takayuki Hirota
- Sex Chromosome Biology Laboratory, The Francis Crick Institute, London, UK
| | - James M A Turner
- Sex Chromosome Biology Laboratory, The Francis Crick Institute, London, UK.
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14
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Zou H, Yu D, Du X, Wang J, Chen L, Wang Y, Xu H, Zhao Y, Zhao S, Pang Y, Liu Y, Hao H, Zhao X, Du W, Dai Y, Li N, Wu S, Zhu H. No imprinted XIST expression in pigs: biallelic XIST expression in early embryos and random X inactivation in placentas. Cell Mol Life Sci 2019; 76:4525-4538. [PMID: 31139846 PMCID: PMC11105601 DOI: 10.1007/s00018-019-03123-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Revised: 04/12/2019] [Accepted: 04/29/2019] [Indexed: 11/29/2022]
Abstract
Dosage compensation, which is achieved by X-chromosome inactivation (XCI) in female mammals, ensures balanced X-linked gene expression levels between the sexes. Although eutherian mammals commonly display random XCI in embryonic and adult tissues, imprinted XCI has also been identified in extraembryonic tissues of mouse, rat, and cow. Little is known about XCI in pigs. Here, we sequenced the porcine XIST gene and identified an insertion/deletion mutation between Asian- and Western-origin pig breeds. Allele-specific analysis revealed biallelic XIST expression in porcine ICSI blastocysts. To investigate the XCI pattern in porcine placentas, we performed allele-specific RNA sequencing analysis on individuals from reciprocal crosses between Duroc and Rongchang pigs. Our results were the first to reveal that random XCI occurs in the placentas of pigs. Next, we investigated the H3K27me3 histone pattern in porcine blastocysts, showing that only 17-31.8% cells have attained XCI. The hypomethylation status of an important XIST DMR (differentially methylated region) in gametes and early embryos demonstrated that no methylation is pre-deposited on XIST in pigs. Our findings reveal that the XCI regulation mechanism in pigs is different from that in mice and highlight the importance of further study of the mechanisms regulating XCI during early porcine embryo development.
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Affiliation(s)
- Huiying Zou
- Key Laboratory of Animal (Poultry) Genetics Breeding and Reproduction, Ministry of Agriculture and Rural Affairs, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, 100193, China
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Dawei Yu
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Xuguang Du
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Jing Wang
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Lei Chen
- Chongqing Academy of Animal Science, Chongqing, 402460, China
| | - Yangyang Wang
- Key Laboratory of Animal (Poultry) Genetics Breeding and Reproduction, Ministry of Agriculture and Rural Affairs, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, 100193, China
| | - Huitao Xu
- Key Laboratory of Animal (Poultry) Genetics Breeding and Reproduction, Ministry of Agriculture and Rural Affairs, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, 100193, China
| | - Yunxuan Zhao
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Shanjiang Zhao
- Key Laboratory of Animal (Poultry) Genetics Breeding and Reproduction, Ministry of Agriculture and Rural Affairs, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, 100193, China
| | - Yunwei Pang
- Key Laboratory of Animal (Poultry) Genetics Breeding and Reproduction, Ministry of Agriculture and Rural Affairs, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, 100193, China
| | - Yan Liu
- Key Laboratory of Animal (Poultry) Genetics Breeding and Reproduction, Ministry of Agriculture and Rural Affairs, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, 100193, China
| | - Haisheng Hao
- Key Laboratory of Animal (Poultry) Genetics Breeding and Reproduction, Ministry of Agriculture and Rural Affairs, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, 100193, China
| | - Xueming Zhao
- Key Laboratory of Animal (Poultry) Genetics Breeding and Reproduction, Ministry of Agriculture and Rural Affairs, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, 100193, China
| | - Weihua Du
- Key Laboratory of Animal (Poultry) Genetics Breeding and Reproduction, Ministry of Agriculture and Rural Affairs, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, 100193, China
| | - Yunping Dai
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Ning Li
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Sen Wu
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing, 100193, China.
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, China Agricultural University, Beijing, 100193, China.
| | - Huabin Zhu
- Key Laboratory of Animal (Poultry) Genetics Breeding and Reproduction, Ministry of Agriculture and Rural Affairs, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, 100193, China.
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15
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Posynick BJ, Brown CJ. Escape From X-Chromosome Inactivation: An Evolutionary Perspective. Front Cell Dev Biol 2019; 7:241. [PMID: 31696116 PMCID: PMC6817483 DOI: 10.3389/fcell.2019.00241] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Accepted: 10/02/2019] [Indexed: 12/14/2022] Open
Abstract
Sex chromosomes originate as a pair of homologus autosomes that then follow a general pattern of divergence. This is evident in mammalian sex chromosomes, which have undergone stepwise recombination suppression events that left footprints of evolutionary strata on the X chromosome. The loss of genes on the Y chromosome led to Ohno’s hypothesis of dosage equivalence between XY males and XX females, which is achieved through X-chromosome inactivation (XCI). This process transcriptionally silences all but one X chromosome in each female cell, although 15–30% of human X-linked genes still escape inactivation. There are multiple evolutionary pathways that may lead to a gene escaping XCI, including remaining Y chromosome homology, or female advantage to escape. The conservation of some escape genes across multiple species and the ability of the mouse inactive X to recapitulate human escape status both suggest that escape from XCI is controlled by conserved processes. Evolutionary pressures to minimize dosage imbalances have led to the accumulation of genetic elements that favor either silencing or escape; lack of dosage sensitivity might also allow for the escape of flanking genes near another escapee, if a boundary element is not present between them. Delineation of the elements involved in escape is progressing, but mechanistic understanding of how they interact to allow escape from XCI is still lacking. Although increasingly well-studied in humans and mice, non-trivial challenges to studying escape have impeded progress in other species. Mouse models that can dissect the role of the sex chromosomes distinct from sex of the organism reveal an important contribution for escape genes to multiple diseases. In humans, with their elevated number of escape genes, the phenotypic consequences of sex chromosome aneuplodies and sexual dimorphism in disease both highlight the importance of escape genes.
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Affiliation(s)
- Bronwyn J Posynick
- Department of Medical Genetics, Molecular Epigenetics Group, Life Sciences Institute, The University of British Columbia, Vancouver, BC, Canada
| | - Carolyn J Brown
- Department of Medical Genetics, Molecular Epigenetics Group, Life Sciences Institute, The University of British Columbia, Vancouver, BC, Canada
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16
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Sprague D, Waters SA, Kirk JM, Wang JR, Samollow PB, Waters PD, Calabrese JM. Nonlinear sequence similarity between the Xist and Rsx long noncoding RNAs suggests shared functions of tandem repeat domains. RNA (NEW YORK, N.Y.) 2019; 25:1004-1019. [PMID: 31097619 PMCID: PMC6633197 DOI: 10.1261/rna.069815.118] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Accepted: 05/14/2019] [Indexed: 05/30/2023]
Abstract
The marsupial inactive X chromosome expresses a long noncoding RNA (lncRNA) called Rsx that has been proposed to be the functional analog of eutherian Xist Despite the possibility that Xist and Rsx encode related functions, the two lncRNAs harbor no linear sequence similarity. However, both lncRNAs harbor domains of tandemly repeated sequence. In Xist, these repeat domains are known to be critical for function. Using k-mer based comparison, we show that the repeat domains of Xist and Rsx unexpectedly partition into two major clusters that each harbor substantial levels of nonlinear sequence similarity. Xist Repeats B, C, and D were most similar to each other and to Rsx Repeat 1, whereas Xist Repeats A and E were most similar to each other and to Rsx Repeats 2, 3, and 4. Similarities at the level of k-mers corresponded to domain-specific enrichment of protein-binding motifs. Within individual domains, protein-binding motifs were often enriched to extreme levels. Our data support the hypothesis that Xist and Rsx encode similar functions through different spatial arrangements of functionally analogous protein-binding domains. We propose that the two clusters of repeat domains in Xist and Rsx function in part to cooperatively recruit PRC1 and PRC2 to chromatin. The physical manner in which these domains engage with protein cofactors may be just as critical to the function of the domains as the protein cofactors themselves. The general approaches we outline in this report should prove useful in the study of any set of RNAs.
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Affiliation(s)
- Daniel Sprague
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
- Curriculum in Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
| | - Shafagh A Waters
- School of Biotechnology and Biomolecular Sciences, Faculty of Science, University of New South Wales, Sydney, New South Wales 2052, Australia
- School of Women's and Children's Health, Faculty of Medicine, University of New South Wales, Sydney, New South Wales 2052, Australia
| | - Jessime M Kirk
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
- Curriculum in Bioinformatics and Computational Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
| | - Jeremy R Wang
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
| | - Paul B Samollow
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas 77843, USA
| | - Paul D Waters
- School of Biotechnology and Biomolecular Sciences, Faculty of Science, University of New South Wales, Sydney, New South Wales 2052, Australia
| | - J Mauro Calabrese
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
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17
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The Methylome of Vertebrate Sex Chromosomes. Genes (Basel) 2018; 9:genes9050230. [PMID: 29723955 PMCID: PMC5977170 DOI: 10.3390/genes9050230] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2018] [Revised: 04/17/2018] [Accepted: 04/26/2018] [Indexed: 01/08/2023] Open
Abstract
DNA methylation is a key epigenetic modification in vertebrate genomes known to be involved in the regulation of gene expression, X chromosome inactivation, genomic imprinting, chromatin structure, and control of transposable elements. DNA methylation is common to all eukaryote genomes, but we still lack a complete understanding of the variation in DNA methylation patterns on sex chromosomes and between the sexes in diverse species. To better understand sex chromosome DNA methylation patterns between different amniote vertebrates, we review literature that has analyzed the genome-wide distribution of DNA methylation in mammals and birds. In each system, we focus on DNA methylation patterns on the autosomes versus the sex chromosomes.
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18
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Abstract
Marsupials and monotremes differ from eutherian mammals in many features of their reproduction and development. Some features appear to be representative of transitional stages in evolution from therapsid reptiles to humans and mice, particularly with respect to the extraembryonic tissues that have undergone remarkable modifications to accommodate reduced egg size and quantity of yolk/deutoplasm, and increasing emphasis on viviparity and placentation. Trophoblast and hypoblast contribute the epithelial layers in most of the extraembryonic membranes and are the first two lineages to differentiate from the embryonic lineage. How they are specified varies greatly among mammals, perhaps largely due to heterochrony in the stage at which they must function. Differences probably also exist in the stage at which lineages are specified relative to the stage at which they fully commit to differentiation. The dogma of sequential commitment to trophoblast and hypoblast with progressive loss of potency may not be a fundamental feature of early mammalian development, but merely a recently acquired developmental pattern in eutherians, or at least mice.
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19
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Waters SA, Livernois AM, Patel H, O’Meally D, Craig JM, Marshall Graves JA, Suter CM, Waters PD. Landscape of DNA Methylation on the Marsupial X. Mol Biol Evol 2017; 35:431-439. [DOI: 10.1093/molbev/msx297] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
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20
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Wang Q, Mank JE, Li J, Yang N, Qu L. Allele-Specific Expression Analysis Does Not Support Sex Chromosome Inactivation on the Chicken Z Chromosome. Genome Biol Evol 2017; 9:619-626. [PMID: 28391319 PMCID: PMC5381566 DOI: 10.1093/gbe/evx031] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/22/2017] [Indexed: 12/27/2022] Open
Abstract
Heterogametic sex chromosomes have evolved many times independently, and in many cases, the loss of functional genes from the sex-limited Y or W chromosome leaves only one functional gene copy on the corresponding X or Z chromosome in the heterogametic sex. Because gene dose often correlates with gene expression level, this difference in gene dose between males and females for X- or Z-linked genes in some cases has selected for chromosome-wide transcriptional dosage compensation mechanisms to counteract any reduction in expression in the heterogametic sex. These mechanisms are thought to restore the balance between sex-linked loci and the autosomal genes they interact with, and this also typically results in equal expression between the sexes. However, dosage compensation in many other species is incomplete, and in the case of birds average expression from males (ZZ) remains higher than in females (ZW). Interestingly, recent reports in chickens and related species have shown that the Z chromosome is expressed less in males than would be expected from two copies of the chromosome, and recent data from cell-based approaches on 11 loci in chicken have suggested that one Z chromosome is partially inactivated in males, in a mechanism thought to be homologous to X inactivation in therian mammals. In the present study, we use controlled crosses in three tissues to test for the presence of Z inactivation in males, which would be expected to bias transcription to the active gene copy (allele-specific expression). We show that for the vast majority of genes on the chicken Z chromosome, males express both parental alleles at statistically similar levels, indicating no Z chromosome inactivation. For those Z chromosome loci with detectable ASE in males, we show that the most likely cause is cis-regulatory variation, rather than Z chromosome inactivation. Taken together, our results indicate that unlike the X chromosome in mammals, Z inactivation does not affect an appreciable number of loci in chicken.
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Affiliation(s)
- Qiong Wang
- Department of Animal Genetics and Breeding, National Engineering Laboratory for Animal Breeding, College of Animal Science and Technology, China Agricultural University, Beijing, China
| | - Judith E Mank
- Department of Genetics Evolution and Environment, University College London, United Kingdom
| | - Junying Li
- Department of Animal Genetics and Breeding, National Engineering Laboratory for Animal Breeding, College of Animal Science and Technology, China Agricultural University, Beijing, China
| | - Ning Yang
- Department of Animal Genetics and Breeding, National Engineering Laboratory for Animal Breeding, College of Animal Science and Technology, China Agricultural University, Beijing, China
| | - Lujiang Qu
- Department of Animal Genetics and Breeding, National Engineering Laboratory for Animal Breeding, College of Animal Science and Technology, China Agricultural University, Beijing, China
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21
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Hillman PR, Christian SGB, Doan R, Cohen ND, Konganti K, Douglas K, Wang X, Samollow PB, Dindot SV. Genomic imprinting does not reduce the dosage of UBE3A in neurons. Epigenetics Chromatin 2017; 10:27. [PMID: 28515788 PMCID: PMC5433054 DOI: 10.1186/s13072-017-0134-4] [Citation(s) in RCA: 14] [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: 03/31/2017] [Accepted: 05/03/2017] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND The ubiquitin protein E3A ligase gene (UBE3A) gene is imprinted with maternal-specific expression in neurons and biallelically expressed in all other cell types. Both loss-of-function and gain-of-function mutations affecting the dosage of UBE3A are associated with several neurodevelopmental syndromes and psychological conditions, suggesting that UBE3A is dosage-sensitive in the brain. The observation that loss of imprinting increases the dosage of UBE3A in brain further suggests that inactivation of the paternal UBE3A allele evolved as a dosage-regulating mechanism. To test this hypothesis, we examined UBE3A transcript and protein levels among cells, tissues, and species with different imprinting states of UBE3A. RESULTS Overall, we found no correlation between the imprinting status and dosage of UBE3A. Importantly, we found that maternal Ube3a protein levels increase in step with decreasing paternal Ube3a protein levels during neurogenesis in mouse, fully compensating for loss of expression of the paternal Ube3a allele in neurons. CONCLUSIONS Based on our findings, we propose that imprinting of UBE3A does not function to reduce the dosage of UBE3A in neurons but rather to regulate some other, as yet unknown, aspect of gene expression or protein function.
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Affiliation(s)
- Paul R. Hillman
- Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77845 USA
- Department of Molecular and Cellular Medicine, College of Medicine, Texas A&M Health Science Center, College Station, TX 77845 USA
| | - Sarah G. B. Christian
- Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77845 USA
| | - Ryan Doan
- Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77845 USA
- Interdisciplinary Genetics Program, College of Agriculture and Life Sciences, Texas A&M University, College Station, TX 77845 USA
| | - Noah D. Cohen
- Department of Large Animal Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX USA
| | - Kranti Konganti
- Institute for Genome Science and Society, Texas A&M University, College Station, TX 77845 USA
| | - Kory Douglas
- Department of Large Animal Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX USA
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843 USA
| | - Xu Wang
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853 USA
| | - Paul B. Samollow
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843 USA
| | - Scott V. Dindot
- Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77845 USA
- Department of Molecular and Cellular Medicine, College of Medicine, Texas A&M Health Science Center, College Station, TX 77845 USA
- Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, 4467 TAMU, College Station, TX 77843 USA
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22
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Weird mammals provide insights into the evolution of mammalian sex chromosomes and dosage compensation. J Genet 2016; 94:567-74. [PMID: 26690510 DOI: 10.1007/s12041-015-0572-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
The deep divergence of mammalian groups 166 and 190 million years ago (MYA) provide genetic variation to explore the evolution of DNA sequence, gene arrangement and regulation of gene expression in mammals. With encouragement from the founder of the field, Mary Lyon, techniques in cytogenetics and molecular biology were progressively adapted to characterize the sex chromosomes of kangaroos and other marsupials, platypus and echidna-and weird rodent species. Comparative gene mapping reveals the process of sex chromosome evolution from their inception 190 MYA (they are autosomal in platypus) to their inevitable end (the Y has disappeared in two rodent lineages). Our X and Y are relatively young, getting their start with the evolution of the sex-determining SRY gene, which triggered progressive degradation of the Y chromosome. Even more recently, sex chromosomes of placental mammals fused with an autosomal region which now makes up most of the Y. Exploration of gene activity patterns over four decades showed that dosage compensation via X-chromosome inactivation is unique to therian mammals, and that this whole chromosome control process is different in marsupials and absent in monotremes and reptiles, and birds. These differences can be exploited to deduce how mammalian sex chromosomes and epigenetic silencing evolved.
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23
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Ka S, Ahn H, Seo M, Kim H, Kim JN, Lee HJ. Status of dosage compensation of X chromosome in bovine genome. Genetica 2016; 144:435-44. [PMID: 27376899 DOI: 10.1007/s10709-016-9912-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Accepted: 06/27/2016] [Indexed: 01/18/2023]
Abstract
Dosage compensation system with X chromosome upregulation and inactivation have evolved to overcome the genetic imbalance between sex chromosomes in both male and female of mammals. Although recent development of chromosome-wide technologies has allowed us to test X upregulation, discrete data processing and analysis methods draw disparate conclusions. A series of expression studies revealed status of dosage compensation in some species belonging to monotremes, marsupials, rodents and primates. However, X upregulation in the Artiodactyla order including cattle have not been studied yet. In this study, we surveyed the genome-wide transcriptional upregulation in X chromosome in cattle RNA-seq data using different gene filtration methods. Overall examination of RNA-seq data revealed that X chromosome in the pituitary gland expressed more genes than in other peripheral tissues, which was consistent with the previous results observed in human and mouse. When analyzed with globally expressed genes, a median X:A expression ratio was 0.94. The ratio of 1-to-1 ortholog genes between chicken and mammals, however, showed considerable reduction to 0.68. These results indicate that status of dosage compensation for cattle is not deviated from those found in rodents and primate, and this is consistent with the evolutionary history of cattle.
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Affiliation(s)
- Sojeong Ka
- Department of Agricultural Biotechnology, College of Agriculture and Life Sciences, Seoul National University, Seoul, 08826, Republic of Korea
| | - Hyeonju Ahn
- Department of Agricultural Biotechnology, College of Agriculture and Life Sciences, Seoul National University, Seoul, 08826, Republic of Korea
| | - Minseok Seo
- Interdisciplinary Program in Bioinformatics, Seoul National University, Seoul, 08826, Republic of Korea
- C&K Genomics Inc., Seoul National University Research Park, Seoul, 08826, Republic of Korea
| | - Heebal Kim
- Department of Agricultural Biotechnology, College of Agriculture and Life Sciences, Seoul National University, Seoul, 08826, Republic of Korea
- Interdisciplinary Program in Bioinformatics, Seoul National University, Seoul, 08826, Republic of Korea
| | - Jin Nam Kim
- C&K Genomics Inc., Seoul National University Research Park, Seoul, 08826, Republic of Korea.
| | - Hyun-Jeong Lee
- Animal Nutritional Physiology Team, National Institute of Animal Science, Jeonju, Jeollabuk-Do, 55365, Republic of Korea.
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24
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Furlan G, Rougeulle C. Function and evolution of the long noncoding RNA circuitry orchestrating X-chromosome inactivation in mammals. WILEY INTERDISCIPLINARY REVIEWS-RNA 2016; 7:702-22. [PMID: 27173581 DOI: 10.1002/wrna.1359] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Revised: 03/30/2016] [Accepted: 03/31/2016] [Indexed: 12/20/2022]
Abstract
X-chromosome inactivation (XCI) is a chromosome-wide regulatory process that ensures dosage compensation for X-linked genes in Theria. XCI is established during early embryogenesis and is developmentally regulated. Different XCI strategies exist in mammalian infraclasses and the regulation of this process varies also among closely related species. In Eutheria, initiation of XCI is orchestrated by a cis-acting locus, the X-inactivation center (Xic), which is particularly enriched in genes producing long noncoding RNAs (lncRNAs). Among these, Xist generates a master transcript that coats and propagates along the future inactive X-chromosome in cis, establishing X-chromosome wide transcriptional repression through interaction with several protein partners. Other lncRNAs also participate to the regulation of X-inactivation but the extent to which their function has been maintained in evolution is still poorly understood. In Metatheria, Xist is not conserved, but another, evolutionary independent lncRNA with similar properties, Rsx, has been identified, suggesting that lncRNA-mediated XCI represents an evolutionary advantage. Here, we review current knowledge on the interplay of X chromosome-encoded lncRNAs in ensuring proper establishment and maintenance of chromosome-wide silencing, and discuss the evolutionary implications of the emergence of species-specific lncRNAs in the control of XCI within Theria. WIREs RNA 2016, 7:702-722. doi: 10.1002/wrna.1359 For further resources related to this article, please visit the WIREs website.
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Affiliation(s)
- Giulia Furlan
- Sorbonne Paris Cité, Epigenetics and Cell Fate, UMR7216 CNRS, Université Paris Diderot, Paris, France
| | - Claire Rougeulle
- Sorbonne Paris Cité, Epigenetics and Cell Fate, UMR7216 CNRS, Université Paris Diderot, Paris, France
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Abstract
Long non-coding RNAs (lncRNAs) are a diverse class of RNAs that engage in numerous biological processes across every branch of life. Although initially discovered as mRNA-like transcripts that do not encode proteins, recent studies have revealed features of lncRNAs that further distinguish them from mRNAs. In this Review, we describe special events in the lifetimes of lncRNAs - before, during and after transcription - and discuss how these events ultimately shape the unique characteristics and functional roles of lncRNAs.
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Affiliation(s)
- Jeffrey J Quinn
- Center for Personal Dynamic Regulomes, Stanford University School of Medicine, Stanford, California 94305, USA.,Department of Bioengineering, Stanford University School of Medicine and School of Engineering, Stanford, California 94305, USA
| | - Howard Y Chang
- Center for Personal Dynamic Regulomes, Stanford University School of Medicine, Stanford, California 94305, USA
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26
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An overview of X inactivation based on species differences. Semin Cell Dev Biol 2016; 56:111-116. [PMID: 26805440 DOI: 10.1016/j.semcdb.2016.01.024] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Revised: 01/14/2016] [Accepted: 01/19/2016] [Indexed: 12/29/2022]
Abstract
X inactivation, a developmental process that takes place in early stages of mammalian embryogenesis, balances the sex difference in dosage of X-linked genes. Although all mammals use this form of dosage compensation, the details differ from one species to another because of variations in the staging of embryogenesis and evolutionary tinkering with the DNA blueprint for development. Such differences provide a broader view of the process than that afforded by a single species. My overview of X inactivation is based on these species variations.
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The X factor: X chromosome dosage compensation in the evolutionarily divergent monotremes and marsupials. Semin Cell Dev Biol 2016; 56:117-121. [PMID: 26806635 DOI: 10.1016/j.semcdb.2016.01.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Revised: 12/21/2015] [Accepted: 01/06/2016] [Indexed: 11/22/2022]
Abstract
Marsupials and monotremes represent evolutionarily divergent lineages from the majority of extant mammals which are eutherian, or placental, mammals. Monotremes possess multiple X and Y chromosomes that appear to have arisen independently of eutherian and marsupial sex chromosomes. Dosage compensation of X-linked genes occurs in monotremes on a gene-by-gene basis, rather than through chromosome-wide silencing, as is the case in eutherians and marsupials. Specifically, studies in the platypus have shown that for any given X-linked gene, a specific proportion of nuclei within a cell population will silence one locus, with the percentage of cells undergoing inactivation at that locus being highly gene-specific. Hence, it is perhaps not surprising that the expression level of X-linked genes in female platypus is almost double that in males. This is in contrast to the situation in marsupials where one of the two X chromosomes is inactivated in females by the long non-coding RNA RSX, a functional analogue of the eutherian XIST. However, marsupial X chromosome inactivation differs from that seen in eutherians in that it is exclusively the paternal X chromosome that is silenced. In addition, marsupials appear to have globally upregulated X-linked gene expression in both sexes, thus balancing their expression levels with those of the autosomes, a process initially proposed by Ohno in 1967 as being a fundamental component of the X chromosome dosage compensation mechanism but which may not have evolved in eutherians.
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Abstract
Differentiated sex chromosomes in mammals and other vertebrates evolved independently but in strikingly similar ways. Vertebrates with differentiated sex chromosomes share the problems of the unequal expression of the genes borne on sex chromosomes, both between the sexes and with respect to autosomes. Dosage compensation of genes on sex chromosomes is surprisingly variable - and can even be absent - in different vertebrate groups. Systems that compensate for different gene dosages include a wide range of global, regional and gene-by-gene processes that differ in their extent and their molecular mechanisms. However, many elements of these control systems are similar across distant phylogenetic divisions and show parallels to other gene silencing systems. These dosage systems cannot be identical by descent but were probably constructed from elements of ancient silencing mechanisms that are ubiquitous among vertebrates and shared throughout eukaryotes.
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Alexander KA, Wang X, Shibata M, Clark AG, García-García MJ. TRIM28 Controls Genomic Imprinting through Distinct Mechanisms during and after Early Genome-wide Reprogramming. Cell Rep 2015; 13:1194-1205. [PMID: 26527006 DOI: 10.1016/j.celrep.2015.09.078] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2015] [Revised: 09/08/2015] [Accepted: 09/25/2015] [Indexed: 01/08/2023] Open
Abstract
Genomic imprinting depends on the establishment and maintenance of DNA methylation at imprinting control regions. However, the mechanisms by which these heritable marks influence allele-specific expression are not fully understood. By analyzing maternal, zygotic, maternal-zygotic, and conditional Trim28 mutants, we found that the transcription factor TRIM28 controls genomic imprinting through distinct mechanisms at different developmental stages. During early genome-wide reprogramming, both maternal and zygotic TRIM28 are required for the maintenance of methylation at germline imprints. However, in conditional Trim28 mutants, Gtl2-imprinted gene expression was lost despite normal methylation levels at the germline IG-DMR. These results provide evidence that TRIM28 controls imprinting after early embryonic reprogramming through a mechanism other than the maintenance of germline imprints. Additionally, our finding that secondary imprints were hypomethylated in TRIM28 mutants uncovers a requirement of TRIM28 after genome-wide reprogramming for interpreting germline imprints and regulating DNA methylation at imprinted gene promoters.
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Affiliation(s)
- Katherine A Alexander
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
| | - Xu Wang
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
| | - Maho Shibata
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
| | - Andrew G Clark
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
| | - María J García-García
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA.
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Slavney A, Arbiza L, Clark AG, Keinan A. Strong Constraint on Human Genes Escaping X-Inactivation Is Modulated by their Expression Level and Breadth in Both Sexes. Mol Biol Evol 2015; 33:384-93. [PMID: 26494842 PMCID: PMC4751236 DOI: 10.1093/molbev/msv225] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
In eutherian mammals, X-linked gene expression is normalized between XX females and XY males through the process of X chromosome inactivation (XCI). XCI results in silencing of transcription from one ChrX homolog per female cell. However, approximately 25% of human ChrX genes escape XCI to some extent and exhibit biallelic expression in females. The evolutionary basis of this phenomenon is not entirely clear, but high sequence conservation of XCI escapers suggests that purifying selection may directly or indirectly drive XCI escape at these loci. One hypothesis is that this signal results from contributions to developmental and physiological sex differences, but presently there is limited evidence supporting this model in humans. Another potential driver of this signal is selection for high and/or broad gene expression in both sexes, which are strong predictors of reduced nucleotide substitution rates in mammalian genes. Here, we compared purifying selection and gene expression patterns of human XCI escapers with those of X-inactivated genes in both sexes. When we accounted for the functional status of each ChrX gene’s Y-linked homolog (or “gametolog”), we observed that XCI escapers exhibit greater degrees of purifying selection in the human lineage than X-inactivated genes, as well as higher and broader gene expression than X-inactivated genes across tissues in both sexes. These results highlight a significant role for gene expression in both sexes in driving purifying selection on XCI escapers, and emphasize these genes’ potential importance in human disease.
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Affiliation(s)
- Andrea Slavney
- Department of Biological Statistics and Computational Biology, Cornell University Department of Molecular Biology and Genetics, Cornell University
| | - Leonardo Arbiza
- Department of Biological Statistics and Computational Biology, Cornell University
| | - Andrew G Clark
- Department of Biological Statistics and Computational Biology, Cornell University Department of Molecular Biology and Genetics, Cornell University
| | - Alon Keinan
- Department of Biological Statistics and Computational Biology, Cornell University
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Global DNA Methylation patterns on marsupial and devil facial tumour chromosomes. Mol Cytogenet 2015; 8:74. [PMID: 26435750 PMCID: PMC4591559 DOI: 10.1186/s13039-015-0176-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2015] [Accepted: 09/19/2015] [Indexed: 12/19/2022] Open
Abstract
Background Despite DNA methylation being one of the most widely studied epigenetic modifications in eukaryotes, only a few studies have examined the global methylation status of marsupial chromosomes. The emergence of devil facial tumour disease (DFTD), a clonally transmissible cancer spreading through the Tasmanian devil population, makes it a particularly pertinent time to determine the methylation status of marsupial and devil facial tumour chromosomes. DNA methylation perturbations are known to play a role in genome instability in human tumours. One of the interesting features of the devil facial tumour is its remarkable karyotypic stability over time as only four strains with minor karyotypic differences having been reported. The cytogenetic monitoring of devil facial tumour (DFT) samples collected over an eight year period and detailed molecular cytogenetic analysis performed on the different DFT strains enables chromosome rearrangements to be correlated with methylation status as the tumour evolves. Results We used immunofluorescent staining with an antibody to 5-methylcytosine on metaphase chromosomes prepared from fibroblast cells of three distantly related marsupials, including the Tasmanian devil, as well as DFTD chromosomes prepared from samples collected from different years and representing different karyotypic strains. Staining of chromosomes from male and female marsupial cell lines indicate species-specific differences in global methylation patterns but with the most intense staining regions corresponding to telomeric and/or centromeric regions of autosomes. In males, the X chromosome was hypermethylated as was one X in females. Similarly, telomeric regions on DFTD chromosomes and regions corresponding to material from one of the two X chromosomes were hypermethylated. No difference in global methylation in samples of the same strain taken in different years was observed. Conclusions The methylation patterns on DFTD chromosomes suggests that the hypermethylated active X was shattered in the formation of the tumour chromosomes, with atypical areas of methylation on DFTD chromosomes corresponding to locations of X chromosome material from the shattered X. The incredibly stable broad methylation patterns observed between strains and over time may reflect the overall genomic stability of the devil facial tumour. Electronic supplementary material The online version of this article (doi:10.1186/s13039-015-0176-x) contains supplementary material, which is available to authorized users.
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Early Developmental and Evolutionary Origins of Gene Body DNA Methylation Patterns in Mammalian Placentas. PLoS Genet 2015; 11:e1005442. [PMID: 26241857 PMCID: PMC4524645 DOI: 10.1371/journal.pgen.1005442] [Citation(s) in RCA: 79] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Accepted: 07/14/2015] [Indexed: 12/11/2022] Open
Abstract
Over the last 20-80 million years the mammalian placenta has taken on a variety of morphologies through both divergent and convergent evolution. Recently we have shown that the human placenta genome has a unique epigenetic pattern of large partially methylated domains (PMDs) and highly methylated domains (HMDs) with gene body DNA methylation positively correlating with level of gene expression. In order to determine the evolutionary conservation of DNA methylation patterns and transcriptional regulatory programs in the placenta, we performed a genome-wide methylome (MethylC-seq) analysis of human, rhesus macaque, squirrel monkey, mouse, dog, horse, and cow placentas as well as opossum extraembryonic membrane. We found that, similar to human placenta, mammalian placentas and opossum extraembryonic membrane have globally lower levels of methylation compared to somatic tissues. Higher relative gene body methylation was the conserved feature across all mammalian placentas, despite differences in PMD/HMDs and absolute methylation levels. Specifically, higher methylation over the bodies of genes involved in mitosis, vesicle-mediated transport, protein phosphorylation, and chromatin modification was observed compared with the rest of the genome. As in human placenta, higher methylation is associated with higher gene expression and is predictive of genic location across species. Analysis of DNA methylation in oocytes and preimplantation embryos shows a conserved pattern of gene body methylation similar to the placenta. Intriguingly, mouse and cow oocytes and mouse early embryos have PMD/HMDs but their placentas do not, suggesting that PMD/HMDs are a feature of early preimplantation methylation patterns that become lost during placental development in some species and following implantation of the embryo.
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Paternal X inactivation does not correlate with X chromosome evolutionary strata in marsupials. BMC Evol Biol 2014; 14:267. [PMID: 25539578 PMCID: PMC4302592 DOI: 10.1186/s12862-014-0267-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Accepted: 12/11/2014] [Indexed: 11/10/2022] Open
Abstract
Background X chromosome inactivation is the transcriptional silencing of one X chromosome in the somatic cells of female mammals. In eutherian mammals (e.g. humans) one of the two X chromosomes is randomly chosen for silencing, with about 15% (usually in younger evolutionary strata of the X chromosome) of genes escaping this silencing. In contrast, in the distantly related marsupial mammals the paternally derived X is silenced, although not as completely as the eutherian X. A chromosome wide examination of X inactivation, using RNA-seq, was recently undertaken in grey short-tailed opossum (Monodelphis domestica) brain and extraembryonic tissues. However, no such study has been conduced in Australian marsupials, which diverged from their American cousins ~80 million years ago, leaving a large gap in our understanding of marsupial X inactivation. Results We used RNA-seq data from blood or liver of a family (mother, father and daughter) of tammar wallabies (Macropus eugenii), which in conjunction with available genome sequence from the mother and father, permitted genotyping of 42 expressed heterozygous SNPs on the daughter’s X. These 42 SNPs represented 34 X loci, of which 68% (23 of the 34) were confirmed as inactivated on the paternally derived X in the daughter’s liver; the remaining 11 X loci escaped inactivation. Seven of the wallaby loci sampled were part of the old X evolutionary stratum, of which three escaped inactivation. Three loci were classified as part of the newer X stratum, of which two escaped inactivation. A meta-analysis of previously published opossum X inactivation data revealed that 5 of 52 genes in the old X stratum escaped inactivation. Conclusions We demonstrate that chromosome wide inactivation of the paternal X is common to an Australian marsupial representative, but that there is more escape from inactivation than reported for opossum (32% v 14%). We also provide evidence that, unlike the human X chromosome, the location of loci within the oldest evolutionary stratum on the marsupial X does not correlate with their probability of escape from inactivation. Electronic supplementary material The online version of this article (doi:10.1186/s12862-014-0267-z) contains supplementary material, which is available to authorized users.
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Bellott DW, Hughes JF, Skaletsky H, Brown LG, Pyntikova T, Cho TJ, Koutseva N, Zaghlul S, Graves T, Rock S, Kremitzki C, Fulton RS, Dugan S, Ding Y, Morton D, Khan Z, Lewis L, Buhay C, Wang Q, Watt J, Holder M, Lee S, Nazareth L, Alföldi J, Rozen S, Muzny DM, Warren WC, Gibbs RA, Wilson RK, Page DC. Mammalian Y chromosomes retain widely expressed dosage-sensitive regulators. Nature 2014; 508:494-9. [PMID: 24759411 PMCID: PMC4139287 DOI: 10.1038/nature13206] [Citation(s) in RCA: 452] [Impact Index Per Article: 45.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2013] [Accepted: 03/06/2014] [Indexed: 12/31/2022]
Abstract
The human X and Y chromosomes evolved from an ordinary pair of autosomes, but
millions of years ago genetic decay ravaged the Y chromosome, and only three percent of
its ancestral genes survived. We reconstructed the evolution of the Y chromosome across
eight mammals to identify biases in gene content and the selective pressures that
preserved the surviving ancestral genes. Our findings indicate that survival was
non-random, and in two cases, convergent across placental and marsupial mammals. We
conclude that the Y chromosome's gene content became specialized through selection
to maintain the ancestral dosage of homologous X-Y gene pairs that function as broadly
expressed regulators of transcription, translation and protein stability. We propose that
beyond its roles in testis determination and spermatogenesis, the Y chromosome is
essential for male viability, and plays unappreciated roles in Turner syndrome and in
phenotypic differences between the sexes in health and disease.
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Affiliation(s)
- Daniel W Bellott
- Whitehead Institute, Howard Hughes Medical Institute, & Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02142, USA
| | - Jennifer F Hughes
- Whitehead Institute, Howard Hughes Medical Institute, & Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02142, USA
| | - Helen Skaletsky
- Whitehead Institute, Howard Hughes Medical Institute, & Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02142, USA
| | - Laura G Brown
- Whitehead Institute, Howard Hughes Medical Institute, & Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02142, USA
| | - Tatyana Pyntikova
- Whitehead Institute, Howard Hughes Medical Institute, & Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02142, USA
| | - Ting-Jan Cho
- Whitehead Institute, Howard Hughes Medical Institute, & Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02142, USA
| | - Natalia Koutseva
- Whitehead Institute, Howard Hughes Medical Institute, & Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02142, USA
| | - Sara Zaghlul
- Whitehead Institute, Howard Hughes Medical Institute, & Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02142, USA
| | - Tina Graves
- The Genome Institute, Washington University School of Medicine, St. Louis, Missouri 63108, USA
| | - Susie Rock
- The Genome Institute, Washington University School of Medicine, St. Louis, Missouri 63108, USA
| | - Colin Kremitzki
- The Genome Institute, Washington University School of Medicine, St. Louis, Missouri 63108, USA
| | - Robert S Fulton
- The Genome Institute, Washington University School of Medicine, St. Louis, Missouri 63108, USA
| | - Shannon Dugan
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas 77030, USA
| | - Yan Ding
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas 77030, USA
| | - Donna Morton
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas 77030, USA
| | - Ziad Khan
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas 77030, USA
| | - Lora Lewis
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas 77030, USA
| | - Christian Buhay
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas 77030, USA
| | - Qiaoyan Wang
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas 77030, USA
| | - Jennifer Watt
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas 77030, USA
| | - Michael Holder
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas 77030, USA
| | - Sandy Lee
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas 77030, USA
| | - Lynne Nazareth
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas 77030, USA
| | - Jessica Alföldi
- Whitehead Institute, Howard Hughes Medical Institute, & Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02142, USA
| | - Steve Rozen
- Whitehead Institute, Howard Hughes Medical Institute, & Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02142, USA
| | - Donna M Muzny
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas 77030, USA
| | - Wesley C Warren
- The Genome Institute, Washington University School of Medicine, St. Louis, Missouri 63108, USA
| | - Richard A Gibbs
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas 77030, USA
| | - Richard K Wilson
- The Genome Institute, Washington University School of Medicine, St. Louis, Missouri 63108, USA
| | - David C Page
- Whitehead Institute, Howard Hughes Medical Institute, & Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02142, USA
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Yao Y, Des Marais TL, Costa M. Chromatin Memory in the Development of Human Cancers. GENE TECHNOLOGY 2014; 3:114. [PMID: 25606572 PMCID: PMC4297643] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Cancer is a complex disease with acquired genomic and epigenomic alterations that affect cell proliferation, viability and invasiveness. Almost all the epigenetic mechanisms including cytosine methylation and hydroxymethylation, chromatin remodeling and non-coding RNAs have been found associate with carcinogenesis and cancer specific expression profile. Altered histone modification as an epigenetic hallmark is frequently found in tumors. Understanding the epigenetic alterations induced by carcinogens or infectious agents may help us understand early epigenetic changes prior to the development of cancer. In this review, we focus on chromatin remodeling and the associated histone modifiers in the development of cancer; the application of these modifiers as a cancer therapy target in different clinical trial phases is also discussed.
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Affiliation(s)
- Yixin Yao
- Department of Environmental Medicine New York University, New York, USA,Corresponding author: Yixin Yao, Department of Environmental Medicine, New York University, New York, USA; Tel: 845-731-3517;
| | | | - Max Costa
- Department of Environmental Medicine New York University, New York, USA,Department of Biochemistry and Molecular Pharmacology, New York University Langone Medical Center, Tuxedo, New York, USA
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36
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Wang X, Clark AG. Using next-generation RNA sequencing to identify imprinted genes. Heredity (Edinb) 2014; 113:156-66. [PMID: 24619182 PMCID: PMC4105452 DOI: 10.1038/hdy.2014.18] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Revised: 12/02/2013] [Accepted: 12/19/2013] [Indexed: 12/15/2022] Open
Abstract
Genomic imprinting is manifested as differential allelic expression (DAE) depending on the parent-of-origin. The most direct way to identify imprinted genes is to directly score the DAE in a context where one can identify which parent transmitted each allele. Because many genes display DAE, simply scoring DAE in an individual is not sufficient to identify imprinted genes. In this paper, we outline many technical aspects of a scheme for identification of imprinted genes that makes use of RNA sequencing (RNA-seq) from tissues isolated from F1 offspring derived from the pair of reciprocal crosses. Ideally, the parental lines are from two inbred strains that are not closely related to each other. Aspects of tissue purity, RNA extraction, library preparation and bioinformatic inference of imprinting are all covered. These methods have already been applied in a number of organisms, and one of the most striking results is the evolutionary fluidity with which novel imprinted genes are gained and lost within genomes. The general methodology is also applicable to a wide range of other biological problems that require quantification of allele-specific expression using RNA-seq, such as cis-regulation of gene expression, X chromosome inactivation and random monoallelic expression.
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Affiliation(s)
- X Wang
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, USA
- Cornell Center for Comparative and Population Genomics, Cornell University, Ithaca, NY, USA
| | - A G Clark
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, USA
- Cornell Center for Comparative and Population Genomics, Cornell University, Ithaca, NY, USA
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37
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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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Deng X, Berletch JB, Nguyen DK, Disteche CM. X chromosome regulation: diverse patterns in development, tissues and disease. Nat Rev Genet 2014; 15:367-78. [PMID: 24733023 PMCID: PMC4117651 DOI: 10.1038/nrg3687] [Citation(s) in RCA: 220] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Genes on the mammalian X chromosome are present in one copy in males and two copies in females. The complex mechanisms that regulate the X chromosome lead to evolutionary and physiological variability in gene expression between species, the sexes, individuals, developmental stages, tissues and cell types. In early development, delayed and incomplete X chromosome inactivation (XCI) in some species causes variability in gene expression. Additional diversity stems from escape from XCI and from mosaicism or XCI skewing in females. This causes sex-specific differences that manifest as differential gene expression and associated phenotypes. Furthermore, the complexity and diversity of X dosage regulation affect the severity of diseases caused by X-linked mutations.
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Affiliation(s)
- Xinxian Deng
- Department of Pathology, School of Medicine, University of Washington, 1959 NE Pacific Street, Seattle, Washington 98115, USA
| | - Joel B Berletch
- Department of Pathology, School of Medicine, University of Washington, 1959 NE Pacific Street, Seattle, Washington 98115, USA
| | - Di K Nguyen
- Department of Pathology, School of Medicine, University of Washington, 1959 NE Pacific Street, Seattle, Washington 98115, USA
| | - Christine M Disteche
- 1] Department of Pathology, School of Medicine, University of Washington, 1959 NE Pacific Street, Seattle, Washington 98115, USA. [2] Department of Medicine, School of Medicine, University of Washington, 1959 NE Pacific Street, Seattle, Washington 98115, USA
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Wang HD, Hou QF, Guo QN, Li T, Wu D, Zhang XP, Chu Y, He M, Xiao H, Guo LJ, Yang K, Liao SX, Zhu BF. DNA methylation study of fetus genome through a genome-wide analysis. BMC Med Genomics 2014; 7:18. [PMID: 24731722 PMCID: PMC3996908 DOI: 10.1186/1755-8794-7-18] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2013] [Accepted: 04/10/2014] [Indexed: 01/15/2023] Open
Abstract
Background DNA methylation is a crucial epigenetic modification of the genome which is involved in embryonic development, transcription, chromatin structure, X chromosome inactivation, genomic imprinting and chromosome stability. Consistent with these important roles, DNA methylation has been demonstrated to be required for vertebrate early embryogenesis and essential for regulating temporal and spatial expression of genes controlling cell fate and differentiation. Further studies have shown that abnormal DNA methylation is associated with human diseases including the embryonic development diseases. We attempt to study the DNA methylation status of CpG islands in fetus related to fetus growth and development. Methods GeneChip® Human Tiling 2.0R Array set is used for analysis of methylated DNA in a whole-genome wide in 8 pairs amniotic fluid and maternal blood DNA samples. Results We found 1 fetus hypermethylation DNA markers and 4 fetus hypomethylation DNA markers though a Genome-wide analysis. These DNA markers all found to be associated with the critical genes for fetus growth and development (SH2D3C gene, EML3 gene, TRIM71 gene, HOXA3 gene and HOXA5 gene). Conclusions These genes can be used as a biomarker for association studying of embryonic development, pathological pregnancy and so on. The present study has provided new and fundamental insights into the roles that DNA methylation has in embryonic development and in the pathological pregnancy.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | - Shi-Xiu Liao
- Medical Genetic Institute of Henan Province, Henan Provincial People's Hospital, People's Hospital of Zhengzhou University, Zhengzhou 450003, PR China.
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Abstract
Genes on the mammalian X chromosome are present in one copy in males and two copies in females. The complex mechanisms that regulate the X chromosome lead to evolutionary and physiological variability in gene expression between species, the sexes, individuals, developmental stages, tissues and cell types. In early development, delayed and incomplete X chromosome inactivation (XCI) in some species causes variability in gene expression. Additional diversity stems from escape from XCI and from mosaicism or XCI skewing in females. This causes sex-specific differences that manifest as differential gene expression and associated phenotypes. Furthermore, the complexity and diversity of X dosage regulation affect the severity of diseases caused by X-linked mutations.
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Deng X, Berletch JB, Nguyen DK, Disteche CM. X chromosome regulation: diverse patterns in development, tissues and disease. Nat Rev Genet 2014. [PMID: 24733023 DOI: 10.1038/nrg3687,+10.1038/nrn3745] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Genes on the mammalian X chromosome are present in one copy in males and two copies in females. The complex mechanisms that regulate the X chromosome lead to evolutionary and physiological variability in gene expression between species, the sexes, individuals, developmental stages, tissues and cell types. In early development, delayed and incomplete X chromosome inactivation (XCI) in some species causes variability in gene expression. Additional diversity stems from escape from XCI and from mosaicism or XCI skewing in females. This causes sex-specific differences that manifest as differential gene expression and associated phenotypes. Furthermore, the complexity and diversity of X dosage regulation affect the severity of diseases caused by X-linked mutations.
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Affiliation(s)
- Xinxian Deng
- Department of Pathology, School of Medicine, University of Washington, 1959 NE Pacific Street, Seattle, Washington 98115, USA
| | - Joel B Berletch
- Department of Pathology, School of Medicine, University of Washington, 1959 NE Pacific Street, Seattle, Washington 98115, USA
| | - Di K Nguyen
- Department of Pathology, School of Medicine, University of Washington, 1959 NE Pacific Street, Seattle, Washington 98115, USA
| | - Christine M Disteche
- 1] Department of Pathology, School of Medicine, University of Washington, 1959 NE Pacific Street, Seattle, Washington 98115, USA. [2] Department of Medicine, School of Medicine, University of Washington, 1959 NE Pacific Street, Seattle, Washington 98115, USA
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Pessia E, Engelstädter J, Marais GAB. The evolution of X chromosome inactivation in mammals: the demise of Ohno's hypothesis? Cell Mol Life Sci 2014; 71:1383-94. [PMID: 24173285 PMCID: PMC11113734 DOI: 10.1007/s00018-013-1499-6] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Revised: 10/11/2013] [Accepted: 10/14/2013] [Indexed: 12/24/2022]
Abstract
Ohno's hypothesis states that dosage compensation in mammals evolved in two steps: a twofold hyperactivation of the X chromosome in both sexes to compensate for gene losses on the Y chromosome, and silencing of one X (X-chromosome inactivation, XCI) in females to restore optimal dosage. Recent tests of this hypothesis have returned contradictory results. In this review, we explain this ongoing controversy and argue that a novel view on dosage compensation evolution in mammals is starting to emerge. Ohno's hypothesis may be true for a few, dosage-sensitive genes only. If so few genes are compensated, then why has XCI evolved as a chromosome-wide mechanism? This and several other questions raised by the new data in mammals are discussed, and future research directions are proposed.
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Affiliation(s)
- Eugénie Pessia
- Laboratoire de Biométrie et Biologie Évolutive, Centre National de la Recherche Scientifique, Université Lyon 1, Bat. Gregor Mendel, 16 rue Raphaël Dubois, 69622, Villeurbanne Cedex, France,
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Genome-wide histone state profiling of fibroblasts from the opossum, Monodelphis domestica, identifies the first marsupial-specific imprinted gene. BMC Genomics 2014; 15:89. [PMID: 24484454 PMCID: PMC3912494 DOI: 10.1186/1471-2164-15-89] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2013] [Accepted: 01/23/2014] [Indexed: 01/05/2023] Open
Abstract
Background Imprinted genes have been extensively documented in eutherian mammals and found to exhibit significant interspecific variation in the suites of genes that are imprinted and in their regulation between tissues and developmental stages. Much less is known about imprinted loci in metatherian (marsupial) mammals, wherein studies have been limited to a small number of genes previously known to be imprinted in eutherians. We describe the first ab initio search for imprinted marsupial genes, in fibroblasts from the opossum, Monodelphis domestica, based on a genome-wide ChIP-seq strategy to identify promoters that are simultaneously marked by mutually exclusive, transcriptionally opposing histone modifications. Results We identified a novel imprinted gene (Meis1) and two additional monoallelically expressed genes, one of which (Cstb) showed allele-specific, but non-imprinted expression. Imprinted vs. allele-specific expression could not be resolved for the third monoallelically expressed gene (Rpl17). Transcriptionally opposing histone modifications H3K4me3, H3K9Ac, and H3K9me3 were found at the promoters of all three genes, but differential DNA methylation was not detected at CpG islands at any of these promoters. Conclusions In generating the first genome-wide histone modification profiles for a marsupial, we identified the first gene that is imprinted in a marsupial but not in eutherian mammals. This outcome demonstrates the practicality of an ab initio discovery strategy and implicates histone modification, but not differential DNA methylation, as a conserved mechanism for marking imprinted genes in all therian mammals. Our findings suggest that marsupials use multiple epigenetic mechanisms for imprinting and support the concept that lineage-specific selective forces can produce sets of imprinted genes that differ between metatherian and eutherian lines.
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