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Jiang D, Zhang J. Ascertainment Bias in the Genomic Test of Positive Selection on Regulatory Sequences. Mol Biol Evol 2024; 41:msad284. [PMID: 38149460 PMCID: PMC10766478 DOI: 10.1093/molbev/msad284] [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: 08/06/2023] [Revised: 11/12/2023] [Accepted: 12/22/2023] [Indexed: 12/28/2023] Open
Abstract
Evolution of gene expression mediated by cis-regulatory changes is thought to be an important contributor to organismal adaptation, but identifying adaptive cis-regulatory changes is challenging due to the difficulty in knowing the expectation under no positive selection. A new approach for detecting positive selection on transcription factor binding sites (TFBSs) was recently developed, thanks to the application of machine learning in predicting transcription factor (TF) binding affinities of DNA sequences. Given a TFBS sequence from a focal species and the corresponding inferred ancestral sequence that differs from the former at n sites, one can predict the TF-binding affinities of many n-step mutational neighbors of the ancestral sequence and obtain a null distribution of the derived binding affinity, which allows testing whether the binding affinity of the real derived sequence deviates significantly from the null distribution. Applying this test genomically to all experimentally identified binding sites of 3 TFs in humans, a recent study reported positive selection for elevated binding affinities of TFBSs. Here, we show that this genomic test suffers from an ascertainment bias because, even in the absence of positive selection for strengthened binding, the binding affinities of known human TFBSs are more likely to have increased than decreased in evolution. We demonstrate by computer simulation that this bias inflates the false positive rate of the selection test. We propose several methods to mitigate the ascertainment bias and show that almost all previously reported positive selection signals disappear when these methods are applied.
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Affiliation(s)
- Daohan Jiang
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI 48109, USA
- Present address: Department of Quantitative and Computational Biology, University of Southern California, Los Angeles, CA 90089, USA
| | - Jianzhi Zhang
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI 48109, USA
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2
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Zhang R, Yang M, Schreiber J, O'Day DR, Turner JMA, Shendure J, Disteche CM, Deng X, Noble WS. Cross-species imputation and comparison of single-cell transcriptomic profiles. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.19.563173. [PMID: 37905060 PMCID: PMC10614954 DOI: 10.1101/2023.10.19.563173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/02/2023]
Abstract
Cross-species comparison and prediction of gene expression profiles are important to understand regulatory changes during evolution and to transfer knowledge learned from model organisms to humans. Single-cell RNA-seq (scRNA-seq) profiles enable us to capture gene expression profiles with respect to variations among individual cells; however, cross-species comparison of scRNA-seq profiles is challenging because of data sparsity, batch effects, and the lack of one-to-one cell matching across species. Moreover, single-cell profiles are challenging to obtain in certain biological contexts, limiting the scope of hypothesis generation. Here we developed Icebear, a neural network framework that decomposes single-cell measurements into factors representing cell identity, species, and batch factors. Icebear enables accurate prediction of single-cell gene expression profiles across species, thereby providing high-resolution cell type and disease profiles in under-characterized contexts. Icebear also facilitates direct cross-species comparison of single-cell expression profiles for conserved genes that are located on the X chromosome in eutherian mammals but on autosomes in chicken. This comparison, for the first time, revealed evolutionary and diverse adaptations of X-chromosome upregulation in mammals.
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Affiliation(s)
- Ran Zhang
- Department of Genome Sciences, University of Washington
- eScience Institute, University of Washington
| | - Mu Yang
- Department of Biomedical Informatics and Medical Education, University of Washington
| | | | - Diana R O'Day
- Brotman Baty Institute for Precision Medicine, University of Washington
| | | | - Jay Shendure
- Department of Genome Sciences, University of Washington
- Brotman Baty Institute for Precision Medicine, University of Washington
- Howard Hughes Medical Institute
- Allen Center for Cell Lineage Tracing
| | - Christine M Disteche
- Department of Laboratory Medicine and Pathology, University of Washington
- Department of Medicine, University of Washington
| | - Xinxian Deng
- Department of Laboratory Medicine and Pathology, University of Washington
| | - William Stafford Noble
- Department of Genome Sciences, University of Washington
- Paul G. Allen School of Computer Science and Engineering, University of Washington
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3
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Jiang D, Zhang J. Ascertainment bias in the genomic test of positive selection on regulatory sequences. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.20.554030. [PMID: 37662307 PMCID: PMC10473660 DOI: 10.1101/2023.08.20.554030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/05/2023]
Abstract
Evolution of gene expression mediated by cis-regulatory changes is thought to be an important contributor to organismal adaptation, but identifying adaptive cis-regulatory changes is challenging due to the difficulty in knowing the expectation under no positive selection. A new approach for detecting positive selection on transcription factor binding sites (TFBSs) was recently developed, thanks to the application of machine learning in predicting transcription factor (TF) binding affinities of DNA sequences. Given a TFBS sequence from a focal species and the corresponding inferred ancestral sequence that differs from the former at n sites, one can predict the TF binding affinities of many n-step mutational neighbors of the ancestral sequence and obtain a null distribution of the derived binding affinity, which allows testing whether the binding affinity of the real derived sequence deviates significantly from the null distribution. Applying this test genomically to all experimentally identified binding sites of three TFs in humans, a recent study reported positive selection for elevated binding affinities of TFBSs. Here we show that this genomic test suffers from an ascertainment bias because, even in the absence of positive selection for strengthened binding, the binding affinities of known human TFBSs are more likely to have increased than decreased in evolution. We demonstrate by computer simulation that this bias inflates the false positive rate of the selection test. We propose several methods to mitigate the ascertainment bias and show that almost all previously reported positive selection signals disappear when these methods are applied.
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Affiliation(s)
- Daohan Jiang
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Jianzhi Zhang
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan 48109, USA
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4
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Rücklé C, Körtel N, Basilicata MF, Busch A, Zhou Y, Hoch-Kraft P, Tretow K, Kielisch F, Bertin M, Pradhan M, Musheev M, Schweiger S, Niehrs C, Rausch O, Zarnack K, Keller Valsecchi CI, König J. RNA stability controlled by m 6A methylation contributes to X-to-autosome dosage compensation in mammals. Nat Struct Mol Biol 2023; 30:1207-1215. [PMID: 37202476 PMCID: PMC10442230 DOI: 10.1038/s41594-023-00997-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Accepted: 04/06/2023] [Indexed: 05/20/2023]
Abstract
In mammals, X-chromosomal genes are expressed from a single copy since males (XY) possess a single X chromosome, while females (XX) undergo X inactivation. To compensate for this reduction in dosage compared with two active copies of autosomes, it has been proposed that genes from the active X chromosome exhibit dosage compensation. However, the existence and mechanisms of X-to-autosome dosage compensation are still under debate. Here we show that X-chromosomal transcripts have fewer m6A modifications and are more stable than their autosomal counterparts. Acute depletion of m6A selectively stabilizes autosomal transcripts, resulting in perturbed dosage compensation in mouse embryonic stem cells. We propose that higher stability of X-chromosomal transcripts is directed by lower levels of m6A, indicating that mammalian dosage compensation is partly regulated by epitranscriptomic RNA modifications.
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Affiliation(s)
| | - Nadine Körtel
- Institute of Molecular Biology (IMB), Mainz, Germany
| | - M Felicia Basilicata
- Institute of Molecular Biology (IMB), Mainz, Germany
- Institute of Human Genetics, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Anke Busch
- Institute of Molecular Biology (IMB), Mainz, Germany
| | - You Zhou
- Buchmann Institute for Molecular Life Sciences (BMLS) & Institute of Molecular Biosciences, Goethe University Frankfurt, Frankfurt, Germany
| | | | | | | | - Marco Bertin
- Institute of Human Genetics, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | | | | | - Susann Schweiger
- Institute of Molecular Biology (IMB), Mainz, Germany
- Institute of Human Genetics, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Christof Niehrs
- Institute of Molecular Biology (IMB), Mainz, Germany
- Division of Molecular Embryology, DKFZ-ZMBH Alliance, Heidelberg, Germany
| | | | - Kathi Zarnack
- Buchmann Institute for Molecular Life Sciences (BMLS) & Institute of Molecular Biosciences, Goethe University Frankfurt, Frankfurt, Germany
| | | | - Julian König
- Institute of Molecular Biology (IMB), Mainz, Germany.
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5
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Xing Z, Zhang Y, Tian Z, Wang M, Xiao W, Zhu C, Zhao S, Zhu Y, Hu L, Kong X. Escaping but not the inactive X-linked protein complex coding genes may achieve X-chromosome dosage compensation and underlie X chromosome inactivation-related diseases. Heliyon 2023; 9:e17721. [PMID: 37449161 PMCID: PMC10336589 DOI: 10.1016/j.heliyon.2023.e17721] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Revised: 06/05/2023] [Accepted: 06/26/2023] [Indexed: 07/18/2023] Open
Abstract
X chromosome dosage compensation (XDC) refers to the process by which X-linked genes acquire expression equivalence between two sexes. Ohno proposed that XDC is achieved by two-fold upregulations of X-linked genes in both sexes and by silencing one X chromosome (X chromosome inactivation, XCI) in females. However, genes subject to two-fold upregulations as well as the underlying mechanism remain unclear. It's reported that gene dosage changes may only affect X-linked dosage-sensitive genes, such as protein complex coding genes (PCGs). Our results showed that in human PCGs are more likely to escape XCI and escaping PCGs (EsP) show two-fold higher expression than inactivated PCGs (InP) or other X-linked genes at RNA and protein levels in both sexes, which suggest that EsP may achieve upregulations and XDC. The higher expressions of EsP possibly result from the upregulations of the single active X chromosome (Xa), rather than escaping expressions from the inactive X chromosome (Xi). EsP genes have relatively high expression levels in humans and lower dN/dS ratios, suggesting that they are likely under stronger selection pressure over evolutionary time. Our study also suggests that SP1 transcription factor is significantly enriched in EsP and may be involved in the up-regulations of EsP on the active X. Finally, human EsP genes in this study are enriched in the toll-like receptor pathway, NF-kB pathway, apoptotic pathway, and abnormal mental, developmental and reproductive phenotypes. These findings suggest misregulations of EsP may be involved in autoimmune, reproductive, and neurological diseases, providing insight for the diagnosis and treatment of these diseases.
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Affiliation(s)
- Zhihao Xing
- Clinical Laboratory, Institute of Pediatrics, Shenzhen Children’s' Hospital, Shenzhen, China
- CAS Key Laboratory of Tissue Microenvironment and Tumor, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, China
| | - Yuchao Zhang
- CAS Key Laboratory of Tissue Microenvironment and Tumor, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, China
| | - Zhongyuan Tian
- Zhoukou Traditional Chinese Medicine Hospital, Zhoukou, Henan, China
| | - Meng Wang
- CAS Key Laboratory of Tissue Microenvironment and Tumor, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, China
| | - Weiwei Xiao
- Clinical Laboratory, Institute of Pediatrics, Shenzhen Children’s' Hospital, Shenzhen, China
| | - Chunqing Zhu
- Clinical Laboratory, Institute of Pediatrics, Shenzhen Children’s' Hospital, Shenzhen, China
| | - Songhui Zhao
- CAS Key Laboratory of Tissue Microenvironment and Tumor, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, China
| | - Yufei Zhu
- CAS Key Laboratory of Tissue Microenvironment and Tumor, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, China
| | - Landian Hu
- CAS Key Laboratory of Tissue Microenvironment and Tumor, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, China
| | - Xiangyin Kong
- CAS Key Laboratory of Tissue Microenvironment and Tumor, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, China
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6
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Qian SH, Xiong YL, Chen L, Geng YJ, Tang XM, Chen ZX. Dynamic Spatial-temporal Expression Ratio of X Chromosome to Autosomes but Stable Dosage Compensation in Mammals. GENOMICS, PROTEOMICS & BIOINFORMATICS 2023; 21:589-600. [PMID: 36031057 PMCID: PMC10787176 DOI: 10.1016/j.gpb.2022.08.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2021] [Revised: 08/03/2022] [Accepted: 08/22/2022] [Indexed: 06/15/2023]
Abstract
In the evolutionary model of dosage compensation, per-allele expression level of the X chromosome has been proposed to have twofold up-regulation to compensate its dose reduction in males (XY) compared to females (XX). However, the expression regulation of X-linked genes is still controversial, and comprehensive evaluations are still lacking. By integrating multi-omics datasets in mammals, we investigated the expression ratios including X to autosomes (X:AA ratio) and X to orthologs (X:XX ratio) at the transcriptome, translatome, and proteome levels. We revealed a dynamic spatial-temporal X:AA ratio during development in humans and mice. Meanwhile, by tracing the evolution of orthologous gene expression in chickens, platypuses, and opossums, we found a stable expression ratio of X-linked genes in humans to their autosomal orthologs in other species (X:XX ≈ 1) across tissues and developmental stages, demonstrating stable dosage compensation in mammals. We also found that different epigenetic regulations contributed to the high tissue specificity and stage specificity of X-linked gene expression, thus affecting X:AA ratios. It could be concluded that the dynamics of X:AA ratios were attributed to the different gene contents and expression preferences of the X chromosome, rather than the stable dosage compensation.
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Affiliation(s)
- Sheng Hu Qian
- Hubei Key Laboratory of Agricultural Bioinformatics, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, China
| | - Yu-Li Xiong
- Hubei Key Laboratory of Agricultural Bioinformatics, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, China
| | - Lu Chen
- Hubei Key Laboratory of Agricultural Bioinformatics, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, China
| | - Ying-Jie Geng
- Hubei Key Laboratory of Agricultural Bioinformatics, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, China
| | - Xiao-Man Tang
- Hubei Key Laboratory of Agricultural Bioinformatics, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, China
| | - Zhen-Xia Chen
- Hubei Key Laboratory of Agricultural Bioinformatics, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, China; Hubei Hongshan Laboratory, College of Biomedicine and Health, Huazhong Agricultural University, Wuhan 430070, China; Interdisciplinary Sciences Institute, Huazhong Agricultural University, Wuhan 430070, China.
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7
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Zhang J. What Has Genomics Taught An Evolutionary Biologist? GENOMICS, PROTEOMICS & BIOINFORMATICS 2023; 21:1-12. [PMID: 36720382 PMCID: PMC10373158 DOI: 10.1016/j.gpb.2023.01.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Revised: 01/06/2023] [Accepted: 01/19/2023] [Indexed: 01/30/2023]
Abstract
Genomics, an interdisciplinary field of biology on the structure, function, and evolution of genomes, has revolutionized many subdisciplines of life sciences, including my field of evolutionary biology, by supplying huge data, bringing high-throughput technologies, and offering a new approach to biology. In this review, I describe what I have learned from genomics and highlight the fundamental knowledge and mechanistic insights gained. I focus on three broad topics that are central to evolutionary biology and beyond-variation, interaction, and selection-and use primarily my own research and study subjects as examples. In the next decade or two, I expect that the most important contributions of genomics to evolutionary biology will be to provide genome sequences of nearly all known species on Earth, facilitate high-throughput phenotyping of natural variants and systematically constructed mutants for mapping genotype-phenotype-fitness landscapes, and assist the determination of causality in evolutionary processes using experimental evolution.
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Affiliation(s)
- Jianzhi Zhang
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI 48109, USA.
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8
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Meisel RP, Asgari D, Schlamp F, Unckless RL. Induction and inhibition of Drosophila X chromosome gene expression are both impeded by the dosage compensation complex. G3 (BETHESDA, MD.) 2022; 12:6632659. [PMID: 35792851 PMCID: PMC9434221 DOI: 10.1093/g3journal/jkac165] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Accepted: 06/16/2022] [Indexed: 12/24/2022]
Abstract
Sex chromosomes frequently differ from the autosomes in the frequencies of genes with sexually dimorphic or tissue-specific expression. Multiple hypotheses have been put forth to explain the unique gene content of the X chromosome, including selection against male-beneficial X-linked alleles, expression limits imposed by the haploid dosage of the X in males, and interference by the dosage compensation complex on expression in males. Here, we investigate these hypotheses by examining differential gene expression in Drosophila melanogaster following several treatments that have widespread transcriptomic effects: bacterial infection, viral infection, and abiotic stress. We found that genes that are induced (upregulated) by these biotic and abiotic treatments are frequently under-represented on the X chromosome, but so are those that are repressed (downregulated) following treatment. We further show that whether a gene is bound by the dosage compensation complex in males can largely explain the paucity of both up- and downregulated genes on the X chromosome. Specifically, genes that are bound by the dosage compensation complex, or close to a dosage compensation complex high-affinity site, are unlikely to be up- or downregulated after treatment. This relationship, however, could partially be explained by a correlation between differential expression and breadth of expression across tissues. Nonetheless, our results suggest that dosage compensation complex binding, or the associated chromatin modifications, inhibit both up- and downregulation of X chromosome gene expression within specific contexts, including tissue-specific expression. We propose multiple possible mechanisms of action for the effect, including a role of Males absent on the first, a component of the dosage compensation complex, as a dampener of gene expression variance in both males and females. This effect could explain why the Drosophila X chromosome is depauperate in genes with tissue-specific or induced expression, while the mammalian X has an excess of genes with tissue-specific expression.
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Affiliation(s)
- Richard P Meisel
- Department of Biology and Biochemistry, University of Houston, 3455 Cullen Blvd, Houston, TX 77204-5001, USA
| | - Danial Asgari
- Department of Biology and Biochemistry, University of Houston, 3455 Cullen Blvd, Houston, TX 77204-5001, USA
| | - Florencia Schlamp
- Department of Medicine, NYU Grossman School of Medicine, 435 E 30th St, New York, NY 10016, USA
| | - Robert L Unckless
- Department of Molecular Biosciences, University of Kansas, 4055 Haworth Hall, 1200 Sunnyside Avenue, Lawrence, KS 66045, USA
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9
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Mammalian X-chromosome inactivation: proposed role in suppression of the male programme in genetic females. J Genet 2022. [DOI: 10.1007/s12041-022-01363-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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10
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Astro V, Alowaysi M, Fiacco E, Saera-Vila A, Cardona-Londoño KJ, Aiese Cigliano R, Adamo A. Pseudoautosomal Region 1 Overdosage Affects the Global Transcriptome in iPSCs From Patients With Klinefelter Syndrome and High-Grade X Chromosome Aneuploidies. Front Cell Dev Biol 2022; 9:801597. [PMID: 35186953 PMCID: PMC8850648 DOI: 10.3389/fcell.2021.801597] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Accepted: 12/28/2021] [Indexed: 01/19/2023] Open
Abstract
Klinefelter syndrome (KS) is the most prevalent aneuploidy in males and is characterized by a 47,XXY karyotype. Less frequently, higher grade sex chromosome aneuploidies (HGAs) can also occur. Here, using a paradigmatic cohort of KS and HGA induced pluripotent stem cells (iPSCs) carrying 49,XXXXY, 48,XXXY, and 47,XXY karyotypes, we identified the genes within the pseudoautosomal region 1 (PAR1) as the most susceptible to dosage-dependent transcriptional dysregulation and therefore potentially responsible for the progressively worsening phenotype in higher grade X aneuploidies. By contrast, the biallelically expressed non-PAR escape genes displayed high interclonal and interpatient variability in iPSCs and differentiated derivatives, suggesting that these genes could be associated with variable KS traits. By interrogating KS and HGA iPSCs at the single-cell resolution we showed that PAR1 and non-PAR escape genes are not only resilient to the X-inactive specific transcript (XIST)-mediated inactivation but also that their transcriptional regulation is disjointed from the absolute XIST expression level. Finally, we explored the transcriptional effects of X chromosome overdosage on autosomes and identified the nuclear respiratory factor 1 (NRF1) as a key regulator of the zinc finger protein X-linked (ZFX). Our study provides the first evidence of an X-dosage-sensitive autosomal transcription factor regulating an X-linked gene in low- and high-grade X aneuploidies.
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Affiliation(s)
- Veronica Astro
- Biological and Environmental Science and Engineering Division, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
| | - Maryam Alowaysi
- Biological and Environmental Science and Engineering Division, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
| | - Elisabetta Fiacco
- Biological and Environmental Science and Engineering Division, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
| | | | - Kelly J. Cardona-Londoño
- Biological and Environmental Science and Engineering Division, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
| | | | - Antonio Adamo
- Biological and Environmental Science and Engineering Division, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
- *Correspondence: Antonio Adamo,
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11
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Shared evolutionary trajectories of three independent neo-sex chromosomes in Drosophila. Genome Res 2021; 31:2069-2079. [PMID: 34675069 PMCID: PMC8559708 DOI: 10.1101/gr.275503.121] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Accepted: 07/22/2021] [Indexed: 11/25/2022]
Abstract
Dosage compensation (DC) on the X Chromosome counteracts the deleterious effects of gene loss on the Y Chromosome. However, DC is not efficient if the X Chromosome also degenerates. This indeed occurs in Drosophila miranda, in which both the neo-Y and the neo-X are under accelerated pseudogenization. To examine the generality of this pattern, we investigated the evolution of two additional neo-sex chromosomes that emerged independently in D. albomicans and D. americana and reanalyzed neo-sex chromosome evolution in D. miranda. Comparative genomic and transcriptomic analyses revealed that the pseudogenization rate on the neo-X is also accelerated in D. albomicans and D. americana although to a lesser extent than in D. miranda. In males, neo-X-linked genes whose neo-Y-linked homologs are pseudogenized tended to be up-regulated more than those whose neo-Y-linked homologs remain functional. Moreover, genes under strong functional constraint and genes highly expressed in the testis tended to remain functional on the neo-X and neo-Y, respectively. Focusing on the D. miranda and D. albomicans neo-sex chromosomes that emerged independently from the same autosome, we further found that the same genes tend to become pseudogenized in parallel on the neo-Y. These genes include Idgf6 and JhI-26, which may be unnecessary or even harmful in males. Our results indicate that neo-sex chromosomes in Drosophila share a common evolutionary trajectory after their emergence, which may prevent sex chromosomes from being an evolutionary dead end.
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12
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Bista B, Wu Z, Literman R, Valenzuela N. Thermosensitive sex chromosome dosage compensation in ZZ/ZW softshell turtles, Apalone spinifera. Philos Trans R Soc Lond B Biol Sci 2021; 376:20200101. [PMID: 34304598 DOI: 10.1098/rstb.2020.0101] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Sex chromosome dosage compensation (SCDC) overcomes gene-dose imbalances that disturb transcriptional networks, as when ZW females or XY males are hemizygous for Z/X genes. Mounting data from non-model organisms reveal diverse SCDC mechanisms, yet their evolution remains obscure, because most informative lineages with variable sex chromosomes are unstudied. Here, we discovered SCDC in turtles and an unprecedented thermosensitive SCDC in eukaryotes. We contrasted RNA-seq expression of Z-genes, their autosomal orthologues, and control autosomal genes in Apalone spinifera (ZZ/ZW) and Chrysemys picta turtles with temperature-dependent sex determination (TSD) (proxy for ancestral expression). This approach disentangled chromosomal context effects on Z-linked and autosomal expression, from lineage effects owing to selection or drift. Embryonic Apalone SCDC is tissue- and age-dependent, regulated gene-by-gene, complete in females via Z-upregulation in both sexes (Type IV) but partial and environmentally plastic via Z-downregulation in males (accentuated at colder temperature), present in female hatchlings and a weakly suggestive in adult liver (Type I). Results indicate that embryonic SCDC evolved with/after sex chromosomes in Apalone's family Tryonichidae, while co-opting Z-gene upregulation present in the TSD ancestor. Notably, Apalone's SCDC resembles pygmy snake's, and differs from the full-SCDC of Anolis lizards who share homologous sex chromosomes (XY), advancing our understanding of how XX/XY and ZZ/ZW systems compensate gene-dose imbalance. This article is part of the theme issue 'Challenging the paradigm in sex chromosome evolution: empirical and theoretical insights with a focus on vertebrates (Part II)'.
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Affiliation(s)
- Basanta Bista
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, IA 50011, USA
| | - Zhiqiang Wu
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, IA 50011, USA.,Guangdong Laboratory for Lingnan Modern Agriculture, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518120, People's Republic of China
| | - Robert Literman
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, IA 50011, USA
| | - Nicole Valenzuela
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, IA 50011, USA
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13
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Couger MB, Roy SW, Anderson N, Gozashti L, Pirro S, Millward LS, Kim M, Kilburn D, Liu KJ, Wilson TM, Epps CW, Dizney L, Ruedas LA, Campbell P. Sex chromosome transformation and the origin of a male-specific X chromosome in the creeping vole. Science 2021; 372:592-600. [PMID: 33958470 DOI: 10.1126/science.abg7019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Accepted: 04/07/2021] [Indexed: 12/17/2022]
Abstract
The mammalian sex chromosome system (XX female/XY male) is ancient and highly conserved. The sex chromosome karyotype of the creeping vole (Microtus oregoni) represents a long-standing anomaly, with an X chromosome that is unpaired in females (X0) and exclusively maternally transmitted. We produced a highly contiguous male genome assembly, together with short-read genomes and transcriptomes for both sexes. We show that M. oregoni has lost an independently segregating Y chromosome and that the male-specific sex chromosome is a second X chromosome that is largely homologous to the maternally transmitted X. Both maternally inherited and male-specific sex chromosomes carry fragments of the ancestral Y chromosome. Consequences of this recently transformed sex chromosome system include Y-like degeneration and gene amplification on the male-specific X, expression of ancestral Y-linked genes in females, and X inactivation of the male-specific chromosome in male somatic cells. The genome of M. oregoni elucidates the processes that shape the gene content and dosage of mammalian sex chromosomes and exemplifies a rare case of plasticity in an ancient sex chromosome system.
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Affiliation(s)
- Matthew B Couger
- Department of Thoracic Surgery, Brigham and Women's Hospital, Boston MA, 02115, USA
| | - Scott W Roy
- Department of Biology, San Francisco State University, San Francisco, CA 94117, USA.,Department of Molecular and Cell Biology, University of California, Merced, Merced, CA 95343, USA
| | - Noelle Anderson
- Department of Molecular and Cell Biology, University of California, Merced, Merced, CA 95343, USA
| | - Landen Gozashti
- Department of Organismic and Evolutionary Biology and Museum of Comparative Zoology, Harvard University, Cambridge, MA 02138, USA
| | - Stacy Pirro
- Iridian Genomes, Inc., Bethesda, MD 20817, USA
| | - Lindsay S Millward
- Department of Fisheries and Wildlife, Oregon State University, Corvallis, OR 97330, USA
| | | | | | | | - Todd M Wilson
- US Forest Service, PNW Research Station, Corvallis, OR 97331, USA
| | - Clinton W Epps
- Department of Fisheries and Wildlife, Oregon State University, Corvallis, OR 97330, USA
| | - Laurie Dizney
- Department of Biology, University of Portland, Portland, OR 97203, USA
| | - Luis A Ruedas
- Department of Biology and Museum of Natural History, Portland State University, Portland, OR 97207, USA
| | - Polly Campbell
- Department of Evolution, Ecology, and Organismal Biology, University of California, Riverside, Riverside, CA 92521, USA.
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14
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Panda A, Zylicz JJ, Pasque V. New Insights into X-Chromosome Reactivation during Reprogramming to Pluripotency. Cells 2020; 9:E2706. [PMID: 33348832 PMCID: PMC7766869 DOI: 10.3390/cells9122706] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2020] [Revised: 12/08/2020] [Accepted: 12/10/2020] [Indexed: 02/06/2023] Open
Abstract
Dosage compensation between the sexes results in one X chromosome being inactivated during female mammalian development. Chromosome-wide transcriptional silencing from the inactive X chromosome (Xi) in mammalian cells is erased in a process termed X-chromosome reactivation (XCR), which has emerged as a paradigm for studying the reversal of chromatin silencing. XCR is linked with germline development and induction of naive pluripotency in the epiblast, and also takes place upon reprogramming somatic cells to induced pluripotency. XCR depends on silencing of the long non-coding RNA (lncRNA) X inactive specific transcript (Xist) and is linked with the erasure of chromatin silencing. Over the past years, the advent of transcriptomics and epigenomics has provided new insights into the transcriptional and chromatin dynamics with which XCR takes place. However, multiple questions remain unanswered about how chromatin and transcription related processes enable XCR. Here, we review recent work on establishing the transcriptional and chromatin kinetics of XCR, as well as discuss a model by which transcription factors mediate XCR not only via Xist repression, but also by direct targeting of X-linked genes.
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Affiliation(s)
- Amitesh Panda
- Laboratory of Cellular Reprogramming and Epigenetic Regulation, Department of Development and Regeneration, Leuven Stem Cell Institute, KU Leuven-University of Leuven, 3000 Leuven, Belgium;
| | - Jan J. Zylicz
- The Novo Nordisk Foundation Center for Stem Cell Biology, University of Copenhagen, 2200 Copenhagen, Denmark;
| | - Vincent Pasque
- Laboratory of Cellular Reprogramming and Epigenetic Regulation, Department of Development and Regeneration, Leuven Stem Cell Institute, KU Leuven-University of Leuven, 3000 Leuven, Belgium;
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15
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The evolution of sex chromosome dosage compensation in animals. J Genet Genomics 2020; 47:681-693. [PMID: 33579636 DOI: 10.1016/j.jgg.2020.10.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 10/03/2020] [Accepted: 10/04/2020] [Indexed: 02/02/2023]
Abstract
The evolution of heteromorphic sex chromosomes shall lead to gene expression dosage problems, as in at least one of the sexes, the sex-linked gene dose has been reduced by half. It has been proposed that the transcriptional output of the whole X or Z chromosome should be doubled for complete dosage compensation in heterogametic sex. However, owing to the variability of the existing methods to determine the transcriptional differences between sex chromosomes and autosomes (S:A ratios) in different studies, we collected more than 500 public RNA-Seq data set from multiple tissues and species in major clades and proposed a unified computational framework for unbiased and comparable measurement of the S:A ratios of multiple species. We also tested the evolution of dosage compensation more directly by assessing changes in the expression levels of the current sex-linked genes relative to those of the ancestral sex-linked genes. We found that in mammals and birds, the S:A ratio is approximately 0.5, whereas in insects, fishes, and flatworms, the S:A ratio is approximately 1.0. Further analysis showed that the fraction of dosage-sensitive housekeeping genes on the X/Z chromosome is significantly correlated with the S:A ratio. In addition, the degree of degeneration of the Y chromosome may be responsible for the change in the S:A ratio in mammals without a dosage compensation mechanism. Our observations offer unequivocal support for the sex chromosome insensitivity hypothesis in animals and suggest that dosage sensitivity states of sex chromosomes are a major factor underlying different evolutionary strategies of dosage compensation.
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16
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Integrated functional genomic analyses of Klinefelter and Turner syndromes reveal global network effects of altered X chromosome dosage. Proc Natl Acad Sci U S A 2020; 117:4864-4873. [PMID: 32071206 PMCID: PMC7060706 DOI: 10.1073/pnas.1910003117] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Turner syndrome (TS) is caused by having only one X chromosome (X0), and Klinefelter syndrome (KS) by having two X chromosomes and one Y chromosome (XXY). In this study we carried out a direct comparison analysis of the effect these chromosome copy number aberrations have on gene expression networks, analyzing genes located on the X chromosome or anywhere else in the genome, in primary samples from KS and TS patients. In both KS and TS, we found gene expression level changes not only in genes on the X chromosome, but also in many genes on all the other chromosomes, revealing a genomewide ripple effect of the chromosome X copy number aberrations. In both Turner syndrome (TS) and Klinefelter syndrome (KS) copy number aberrations of the X chromosome lead to various developmental symptoms. We report a comparative analysis of TS vs. KS regarding differences at the genomic network level measured in primary samples by analyzing gene expression, DNA methylation, and chromatin conformation. X-chromosome inactivation (XCI) silences transcription from one X chromosome in female mammals, on which most genes are inactive, and some genes escape from XCI. In TS, almost all differentially expressed escape genes are down-regulated but most differentially expressed inactive genes are up-regulated. In KS, differentially expressed escape genes are up-regulated while the majority of inactive genes appear unchanged. Interestingly, 94 differentially expressed genes (DEGs) overlapped between TS and female and KS and male comparisons; and these almost uniformly display expression changes into opposite directions. DEGs on the X chromosome and the autosomes are coexpressed in both syndromes, indicating that there are molecular ripple effects of the changes in X chromosome dosage. Six potential candidate genes (RPS4X, SEPT6, NKRF, CX0rf57, NAA10, and FLNA) for KS are identified on Xq, as well as candidate central genes on Xp for TS. Only promoters of inactive genes are differentially methylated in both syndromes while escape gene promoters remain unchanged. The intrachromosomal contact map of the X chromosome in TS exhibits the structure of an active X chromosome. The discovery of shared DEGs indicates the existence of common molecular mechanisms for gene regulation in TS and KS that transmit the gene dosage changes to the transcriptome.
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17
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Abstract
Diverse dosage compensation mechanisms have evolved across species to equalize gene expression between sexes and between the sex chromosomes and autosomes. New results show that two opposite modes of dosage compensation can occur within one species, the monarch butterfly.
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Affiliation(s)
- Jingyue Duan
- Department of Molecular Biology, Cellular Biology and Biochemistry, Brown University, Providence, RI 02912, USA
| | - Erica N Larschan
- Department of Molecular Biology, Cellular Biology and Biochemistry, Brown University, Providence, RI 02912, USA.
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18
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Gu L, Reilly PF, Lewis JJ, Reed RD, Andolfatto P, Walters JR. Dichotomy of Dosage Compensation along the Neo Z Chromosome of the Monarch Butterfly. Curr Biol 2019; 29:4071-4077.e3. [PMID: 31735674 DOI: 10.1016/j.cub.2019.09.056] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Revised: 09/17/2019] [Accepted: 09/20/2019] [Indexed: 10/25/2022]
Abstract
Mechanisms of sex chromosome dosage compensation (SCDC) differ strikingly among animals. In Drosophila flies, chromosome-wide transcription is doubled from the single X chromosome in hemizygous (XY) males, whereas in Caenorhabditis nematodes, expression is halved for both X copies in homozygous (XX) females [1, 2]. Unlike other female-heterogametic (WZ female and ZZ male) animals, moths and butterflies exhibit sex chromosome dosage compensation patterns typically seen only in male-heterogametic species [3]. The monarch butterfly carries a newly derived Z chromosome segment that arose from an autosomal fusion with the ancestral Z [4]. Using a highly contiguous genome assembly, we show that gene expression is balanced between sexes along the entire Z chromosome but with distinct modes of compensation on the two segments. On the ancestral Z segment, depletion of H4K16ac corresponds to nearly halving of biallelic transcription in males, a pattern convergent to nematodes. Conversely, the newly derived Z segment shows a Drosophila-like mode of compensation, with enriched H4K16ac levels corresponding to doubled monoallelic transcription in females. Our work reveals that, contrary to the expectation of co-opting regulatory mechanisms readily in place, the evolution of plural modes of dosage compensation is also possible along a single sex chromosome within a species.
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Affiliation(s)
- Liuqi Gu
- Department of Ecology and Evolutionary Biology, The University of Kansas, Lawrence, KS 66045, USA.
| | - Patrick F Reilly
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA
| | - James J Lewis
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY 14850, USA
| | - Robert D Reed
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY 14850, USA
| | - Peter Andolfatto
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA
| | - James R Walters
- Department of Ecology and Evolutionary Biology, The University of Kansas, Lawrence, KS 66045, USA.
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19
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Chen Y, Li K, Chu X, Carey LB, Qian W. Synchronized replication of genes encoding the same protein complex in fast-proliferating cells. Genome Res 2019; 29:1929-1938. [PMID: 31662304 PMCID: PMC6886510 DOI: 10.1101/gr.254342.119] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Accepted: 10/28/2019] [Indexed: 02/07/2023]
Abstract
DNA replication perturbs the dosage balance among genes; at mid-S phase, early-replicating genes have doubled their copies while late-replicating ones have not. Dosage imbalance among genes, especially within members of a protein complex, is toxic to cells. However, the molecular mechanisms that cells use to deal with such imbalance remain not fully understood. Here, we validate at the genomic scale that the dosage between early- and late-replicating genes is imbalanced in HeLa cells. We propose the synchronized replication hypothesis that genes sensitive to stoichiometric relationships will be replicated simultaneously to maintain stoichiometry. In support of this hypothesis, we observe that genes encoding the same protein complex have similar replication timing but mainly in fast-proliferating cells such as embryonic stem cells and cancer cells. We find that the synchronized replication observed in cancer cells, but not in slow-proliferating differentiated cells, is due to convergent evolution during tumorigenesis that restores synchronized replication timing within protein complexes. Taken together, our study reveals that the demand for dosage balance during S phase plays an important role in the optimization of the replication-timing program; this selection is relaxed during differentiation as the cell cycle prolongs and is restored during tumorigenesis as the cell cycle shortens.
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Affiliation(s)
- Ying Chen
- State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.,Key Laboratory of Genetic Network Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Ke Li
- State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.,Key Laboratory of Genetic Network Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Xiao Chu
- State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.,Key Laboratory of Genetic Network Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Lucas B Carey
- Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Barcelona 08003, Spain.,Center for Quantitative Biology and Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
| | - Wenfeng Qian
- State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.,Key Laboratory of Genetic Network Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.,University of Chinese Academy of Sciences, Beijing 100049, China
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20
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Larsson AJM, Coucoravas C, Sandberg R, Reinius B. X-chromosome upregulation is driven by increased burst frequency. Nat Struct Mol Biol 2019; 26:963-969. [PMID: 31582851 DOI: 10.1038/s41594-019-0306-y] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Accepted: 08/20/2019] [Indexed: 12/14/2022]
Abstract
Ohno's hypothesis postulates that upregulation of X-linked genes rectifies their dosage imbalance relative to autosomal genes, which are present in two active copies per cell. Here we have dissected X-chromosome upregulation into the kinetics of transcription, inferred from allele-specific single-cell RNA sequencing data from somatic and embryonic mouse cells. We confirmed increased X-chromosome expression levels in female and male cells and found that the X chromosome achieved upregulation by elevated burst frequencies. By monitoring transcriptional kinetics in differentiating female mouse embryonic stem cells, we found that increased burst frequency was established on the active X chromosome when X inactivation took place on the other allele. Thus, our study provides mechanistic insights into X-chromosome upregulation.
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Affiliation(s)
- Anton J M Larsson
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden
| | - Christos Coucoravas
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Rickard Sandberg
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden
| | - Björn Reinius
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden.
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21
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Picard MAL, Vicoso B, Roquis D, Bulla I, Augusto RC, Arancibia N, Grunau C, Boissier J, Cosseau C. Dosage Compensation throughout the Schistosoma mansoni Lifecycle: Specific Chromatin Landscape of the Z Chromosome. Genome Biol Evol 2019; 11:1909-1922. [PMID: 31273378 PMCID: PMC6628874 DOI: 10.1093/gbe/evz133] [Citation(s) in RCA: 10] [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] [Accepted: 06/15/2019] [Indexed: 12/12/2022] Open
Abstract
Differentiated sex chromosomes are accompanied by a difference in gene dose between X/Z-specific and autosomal genes. At the transcriptomic level, these sex-linked genes can lead to expression imbalance, or gene dosage can be compensated by epigenetic mechanisms and results into expression level equalization. Schistosoma mansoni has been previously described as a ZW species (i.e., female heterogamety, in opposition to XY male heterogametic species) with a partial dosage compensation, but underlying mechanisms are still unexplored. Here, we combine transcriptomic (RNA-Seq) and epigenetic data (ChIP-Seq against H3K4me3, H3K27me3, and H4K20me1 histone marks) in free larval cercariae and intravertebrate parasitic stages. For the first time, we describe differences in dosage compensation status in ZW females, depending on the parasitic status: free cercariae display global dosage compensation, whereas intravertebrate stages show a partial dosage compensation. We also highlight regional differences of gene expression along the Z chromosome in cercariae, but not in the intravertebrate stages. Finally, we feature a consistent permissive chromatin landscape of the Z chromosome in both sexes and stages. We argue that dosage compensation in schistosomes is characterized by chromatin remodeling mechanisms in the Z-specific region.
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Affiliation(s)
- Marion A L Picard
- Université de Perpignan Via Domitia, IHPE UMR 5244, CNRS, IFREMER, Université de Montpellier, Perpignan, France
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - Beatriz Vicoso
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - David Roquis
- Université de Perpignan Via Domitia, IHPE UMR 5244, CNRS, IFREMER, Université de Montpellier, Perpignan, France
| | - Ingo Bulla
- Université de Perpignan Via Domitia, IHPE UMR 5244, CNRS, IFREMER, Université de Montpellier, Perpignan, France
| | - Ronaldo C Augusto
- Université de Perpignan Via Domitia, IHPE UMR 5244, CNRS, IFREMER, Université de Montpellier, Perpignan, France
| | - Nathalie Arancibia
- Université de Perpignan Via Domitia, IHPE UMR 5244, CNRS, IFREMER, Université de Montpellier, Perpignan, France
| | - Christoph Grunau
- Université de Perpignan Via Domitia, IHPE UMR 5244, CNRS, IFREMER, Université de Montpellier, Perpignan, France
| | - Jérôme Boissier
- Université de Perpignan Via Domitia, IHPE UMR 5244, CNRS, IFREMER, Université de Montpellier, Perpignan, France
| | - Céline Cosseau
- Université de Perpignan Via Domitia, IHPE UMR 5244, CNRS, IFREMER, Université de Montpellier, Perpignan, France
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22
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Yang JR, Chen X. Dosage sensitivity of X-linked genes in human embryonic single cells. BMC Genomics 2019; 20:42. [PMID: 30642250 PMCID: PMC6332578 DOI: 10.1186/s12864-019-5432-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Accepted: 01/03/2019] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND During the evolution of mammalian sex chromosomes, the degeneration of Y-linked homologs has led to a dosage imbalance between X-linked and autosomal genes. The evolutionary resolution to such dosage imbalance, as hypothesized by Susumu Ohno fifty years ago, should be doubling the expression of X-linked genes. Recent studies have nevertheless shown that the X to autosome expression ratio equals ~ 1 in haploid human parthenogenetic embryonic stem (pES) cells and ~ 0.5 in diploid pES cells, suggesting no doubled expression for X-linked genes and refuting Ohno's hypothesis. RESULTS Here, by reanalyzing an RNA-seq-based single-cell transcriptome dataset of human embryos, we found that from the 8-cell stage until the time-point just prior to implantation, the expression levels of X-linked genes are not two-fold upregulated in male cells and gradually decrease from two-fold in female cells. Additional analyses of gene expression noise further suggest that the dosage sensitivity of X-linked genes is weaker than that of autosomal genes in differentiated female cells, which contradicts a key assumption in Ohno's hypothesis, that most X-linked genes are dosage sensitive. Moreover, the dosage-sensitive housekeeping genes are preferentially located on autosomes, implying selection against X-linkage for dosage-sensitive genes. CONCLUSIONS We observed dosage imbalance between X-linked and autosomal genes, as well as relatively high expression noise from X-linked genes. These results collectively suggest that X-linked genes are less dosage sensitive than autosomal genes, putting one primary assumption of Ohno's hypothesis in question.
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Affiliation(s)
- Jian-Rong Yang
- Department of Biology, Zhongshan School of Medicine, Sun Yat-sen University, 1227 Medical Science and Technology Building, 74 Zhongshan 2nd Road, Guangzhou, 510080, Guangdong, China. .,RNA Biomedical Institute, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, 510120, China. .,Program in Cancer Research, The Fifth Affiliated Hospital, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China.
| | - Xiaoshu Chen
- Department of Medical Genetics, Zhongshan School of Medicine, Sun Yat-sen University, 1212 Medical Science and Technology Building, 74 Zhongshan 2nd Road, Guangzhou, 510080, Guangdong, China.
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23
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Duan JE, Flock K, Jue N, Zhang M, Jones A, Seesi SA, Mandoiu I, Pillai S, Hoffman M, O'Neill R, Zinn S, Govoni K, Reed S, Jiang H, Jiang ZC, Tian XC. Dosage Compensation and Gene Expression of the X Chromosome in Sheep. G3 (BETHESDA, MD.) 2019; 9:305-314. [PMID: 30482800 PMCID: PMC6325915 DOI: 10.1534/g3.118.200815] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Accepted: 11/26/2018] [Indexed: 12/20/2022]
Abstract
Ohno's hypothesis predicts that the expression of the single X chromosome in males needs compensatory upregulation to balance its dosage with that of the diploid autosomes. Additionally, X chromosome inactivation ensures that quadruple expression of the two X chromosomes is avoided in females. These mechanisms have been actively studied in mice and humans but lag behind in domestic species. Using RNA sequencing data, we analyzed the X chromosome upregulation in sheep fetal tissues from day 135 of gestation under control, over or restricted maternal diets (100%, 140% and 60% of National Research Council Total Digestible Nutrients), and in conceptuses, juvenile, and adult somatic tissues. By computing the mean expression ratio of all X-linked genes to all autosomal genes (X:A), we found that all samples displayed some levels of X chromosome upregulation. The degrees of X upregulation were not significant (P-value = 0.74) between ovine females and males in the same somatic tissues. Brain, however, displayed complete X upregulation. Interestingly, the male and female reproduction-related tissues exhibited divergent X dosage upregulation. Moreover, expression upregulation of the X chromosome in fetal tissues was not affected by maternal diets. Maternal nutrition, however, did change expression levels of several X-linked genes, such as sex determination genes SOX3 and NR0B1 In summary, our results showed that X chromosome upregulation occurred in nearly all sheep somatic tissues analyzed, thus support Ohno's hypothesis in a new species. However, the levels of upregulation differed by different subgroups of genes such as those that are house-keeping and "dosage-sensitive".
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Affiliation(s)
| | | | - Nathanial Jue
- School of Natural Sciences, California State University, Monterey Bay, Seaside, CA 93955
| | - Mingyuan Zhang
- Department of Animal Science
- Laboratory Animal Center, Guangxi Medical University, Nanning 530021, China
| | | | - Sahar Al Seesi
- Smith College Department of Computer Science, Northampton, MA 01063
- Department of Computer Science
| | | | | | | | - Rachel O'Neill
- Department of Molecular and Cell Biology, and University of Connecticut, Storrs, CT, 06269
| | | | | | | | - Hesheng Jiang
- College of Animal Science and Technology, Guangxi University, Nanning 530004, China, and
| | - Zongliang Carl Jiang
- Department of Animal Science
- School of Animal Science, Louisiana State University, Baton Rouge, LA 70803
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24
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Duan JE, Shi W, Jue NK, Jiang Z, Kuo L, O'Neill R, Wolf E, Dong H, Zheng X, Chen J, Tian XC. Dosage Compensation of the X Chromosomes in Bovine Germline, Early Embryos, and Somatic Tissues. Genome Biol Evol 2019; 11:242-252. [PMID: 30566637 PMCID: PMC6354180 DOI: 10.1093/gbe/evy270] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/12/2018] [Indexed: 12/15/2022] Open
Abstract
Dosage compensation of the mammalian X chromosome (X) was proposed by Susumu Ohno as a mechanism wherein the inactivation of one X in females would lead to doubling the expression of the other. This would resolve the dosage imbalance between eutherian females (XX) versus male (XY) and between a single active X versus autosome pairs (A). Expression ratio of X- and A-linked genes has been relatively well studied in humans and mice, despite controversial results over the existence of upregulation of X-linked genes. Here we report the first comprehensive test of Ohno’s hypothesis in bovine preattachment embryos, germline, and somatic tissues. Overall an incomplete dosage compensation (0.5 < X:A < 1) of expressed genes and an excess X dosage compensation (X:A > 1) of ubiquitously expressed “dosage-sensitive” genes were seen. No significant differences in X:A ratios were observed between bovine female and male somatic tissues, further supporting Ohno’s hypothesis. Interestingly, preimplantation embryos manifested a unique pattern of X dosage compensation dynamics. Specifically, X dosage decreased after fertilization, indicating that the sperm brings in an inactive X to the matured oocyte. Subsequently, the activation of the bovine embryonic genome enhanced expression of X-linked genes and increased the X dosage. As a result, an excess compensation was exhibited from the 8-cell stage to the compact morula stage. The X dosage peaked at the 16-cell stage and stabilized after the blastocyst stage. Together, our findings confirm Ohno’s hypothesis of X dosage compensation in the bovine and extend it by showing incomplete and over-compensation for expressed and “dosage-sensitive” genes, respectively.
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Affiliation(s)
| | - Wei Shi
- Department of Statistics, University of Connecticut, Storrs, CT
| | - Nathaniel K Jue
- School of Natural Sciences, California State University, Monterey Bay, CA
| | - Zongliang Jiang
- School of Animal Science, Louisiana State University, Agricultural Center, Baton Rouge, LA
| | - Lynn Kuo
- Department of Statistics, University of Connecticut, Storrs, CT
| | - Rachel O'Neill
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT
| | - Eckhard Wolf
- Gene Center and Department of Biochemistry, Ludwig-Maximilians-Universität Muünchen, Germany
| | - Hong Dong
- Institute of Animal Science, Xinjiang Academy of Animal Sciences, Urumqi, Xinjiang, P.R. China
| | - Xinbao Zheng
- Institute of Animal Science, Xinjiang Academy of Animal Sciences, Urumqi, Xinjiang, P.R. China
| | - Jingbo Chen
- Institute of Animal Science, Xinjiang Academy of Animal Sciences, Urumqi, Xinjiang, P.R. China
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25
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Affiliation(s)
- Roberta Bergero
- Institute of Evolutionary Biology, University of Edinburgh, Edinburgh, UK.
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26
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Nozawa M, Ikeo K, Gojobori T. Gene-by-Gene or Localized Dosage Compensation on the Neo-X Chromosome in Drosophila miranda. Genome Biol Evol 2018; 10:1875-1881. [PMID: 29986000 PMCID: PMC6071650 DOI: 10.1093/gbe/evy148] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/06/2018] [Indexed: 12/31/2022] Open
Abstract
Many organisms have a global mechanism for dosage compensation (DC) operating along the entire male X chromosome, which equalizes gene expression on the male X with that on the two Xs in females and/or on autosomes. At the initial stage of sex chromosome evolution, however, gene-by-gene (or localized) DC may also be necessary because the degeneration of Y-linked genes occurs independently at different times. We therefore tested whether the up-regulation of X-linked genes depends on the status of their Y-linked homologs, using the young sex chromosomes, neo-X and neo-Y, in Drosophila miranda. In support of the presence of gene-by-gene DC, the extent of up-regulation in males was indeed higher for neo-X-linked genes with pseudogenized neo-Y-linked homologs than for neo-X-linked genes with functional neo-Y-linked homologs. Further molecular evolutionary analysis also supports the idea that many individual neo-X-linked genes first acquired the potential for up-regulation, which then enabled the pseudogenization of neo-Y-linked homologs, without serious deleterious effects on male fitness.
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Affiliation(s)
- Masafumi Nozawa
- Department of Biological Sciences, Tokyo Metropolitan University, Hachioji, Japan
- Research Center for Genomics and Bioinformatics, Tokyo Metropolitan University, Hachioji, Japan
| | - Kazuho Ikeo
- Center for Information Biology, National Institute of Genetics, Mishima, Japan
- Department of Genetics, SOKENDAI, Mishima, Japan
| | - Takashi Gojobori
- King Abdullah University of Science and Technology (KAUST), Biological and Environmental Science and Engineering, Computational Bioscience Research Center, Thuwal, Kingdom of Saudi Arabia
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27
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Picard MAL, Cosseau C, Ferré S, Quack T, Grevelding CG, Couté Y, Vicoso B. Evolution of gene dosage on the Z-chromosome of schistosome parasites. eLife 2018; 7:e35684. [PMID: 30044216 PMCID: PMC6089595 DOI: 10.7554/elife.35684] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Accepted: 07/16/2018] [Indexed: 12/05/2022] Open
Abstract
XY systems usually show chromosome-wide compensation of X-linked genes, while in many ZW systems, compensation is restricted to a minority of dosage-sensitive genes. Why such differences arose is still unclear. Here, we combine comparative genomics, transcriptomics and proteomics to obtain a complete overview of the evolution of gene dosage on the Z-chromosome of Schistosoma parasites. We compare the Z-chromosome gene content of African (Schistosoma mansoni and S. haematobium) and Asian (S. japonicum) schistosomes and describe lineage-specific evolutionary strata. We use these to assess gene expression evolution following sex-linkage. The resulting patterns suggest a reduction in expression of Z-linked genes in females, combined with upregulation of the Z in both sexes, in line with the first step of Ohno's classic model of dosage compensation evolution. Quantitative proteomics suggest that post-transcriptional mechanisms do not play a major role in balancing the expression of Z-linked genes.
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Affiliation(s)
| | - Celine Cosseau
- University of Perpignan Via Domitia, IHPE UMR 5244, CNRS, IFREMER, University MontpellierPerpignanFrance
| | - Sabrina Ferré
- Université Grenoble Alpes, CEA, Inserm, BIG-BGEGrenobleFrance
| | - Thomas Quack
- Institute for Parasitology, Biomedical Research Center SeltersbergJustus-Liebig-UniversityGiessenGermany
| | - Christoph G Grevelding
- Institute for Parasitology, Biomedical Research Center SeltersbergJustus-Liebig-UniversityGiessenGermany
| | - Yohann Couté
- Université Grenoble Alpes, CEA, Inserm, BIG-BGEGrenobleFrance
| | - Beatriz Vicoso
- Institute of Science and Technology AustriaKlosterneuburgAustria
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28
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Gu L, Walters JR. Evolution of Sex Chromosome Dosage Compensation in Animals: A Beautiful Theory, Undermined by Facts and Bedeviled by Details. Genome Biol Evol 2018; 9:2461-2476. [PMID: 28961969 PMCID: PMC5737844 DOI: 10.1093/gbe/evx154] [Citation(s) in RCA: 70] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/22/2017] [Indexed: 12/17/2022] Open
Abstract
Many animals with genetic sex determination harbor heteromorphic sex chromosomes, where the heterogametic sex has half the gene dose of the homogametic sex. This imbalance, if reflected in the abundance of transcripts or proteins, has the potential to deleteriously disrupt interactions between X-linked and autosomal loci in the heterogametic sex. Classical theory predicts that molecular mechanisms will evolve to provide dosage compensation that recovers expression levels comparable to ancestral expression prior to sex chromosome divergence. Such dosage compensating mechanisms may also, secondarily, result in balanced sex-linked gene expression between males and females. However, numerous recent studies addressing sex chromosome dosage compensation (SCDC) in a diversity of animals have yielded a surprising array of patterns concerning dosage compensation in the heterogametic sex, as well as dosage balance between sexes. These results substantially contradict longstanding theory, catalyzing both novel perspectives and new approaches in dosage compensation research. In this review, we summarize the theory, analytical approaches, and recent results concerning evolutionary patterns of SCDC in animals. We also discuss methodological challenges and discrepancies encountered in this research, which often underlie conflicting results. Finally, we discuss what outstanding questions and opportunities exist for future research on SCDC.
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Affiliation(s)
- Liuqi Gu
- Department of Ecology & Evolution, University of Kansas
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29
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Rajpathak SN, Deobagkar DD. Aneuploidy: an important model system to understand salient aspects of functional genomics. Brief Funct Genomics 2018; 17:181-190. [PMID: 29228117 DOI: 10.1093/bfgp/elx041] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Maintaining a balance in gene dosage and protein activity is essential to sustain normal cellular functions. Males and females have a wide range of genetic as well as epigenetic differences, where X-linked gene dosage is an essential regulatory factor. Basic understanding of gene dosage maintenance has emerged from the studies carried out using mouse models with FCG (four core genotype) and chromosomal aneuploidy as well as from mono-chromosomal hybrid cells. In mammals, aneuploidy often leads to embryonic lethality particularly in early development with major developmental and structural abnormalities. Thus, in-depth analysis of the causes and consequences of gene dosage alterations is needed to unravel its effects on basic cellular and developmental functions as well as in understanding its medical implications. Cells isolated from individuals with naturally occurring chromosomal aneuploidy can be considered as true representatives, as these cells have stable chromosomal alterations/gene dosage imbalance, which have occurred by modulation of the basic molecular machinery. Therefore, innovative use of these natural aneuploidy cells/organisms with recent molecular and high-throughput techniques will provide an understanding of the basic mechanisms involved in gene dosage balance and the related consequences for functional genomics.
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30
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Systematic analysis and comparison of the PHD-Finger gene family in Chinese pear (Pyrus bretschneideri) and its role in fruit development. Funct Integr Genomics 2018; 18:519-531. [PMID: 29675811 DOI: 10.1007/s10142-018-0609-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2017] [Revised: 04/02/2018] [Accepted: 04/09/2018] [Indexed: 12/16/2022]
Abstract
PHD-finger proteins, which belongs to the type of zinc finger family, and that play an important role in the regulation of both transcription and the chromatin state in eukaryotes. Currently, PHD-finger proteins have been well studied in animals, while few studies have been carried out on their function in plants. In the present study, 129 non-redundant PHD-finger genes were identified from 5 Rosaceae species (pear, apple, strawberry, mei, and peach); among them, 31 genes were identified in pear. Subsequently, we carried out a bioinformatics analysis of the PHD-finger genes. Thirty-one PbPHD genes were divided into 7 subfamilies based on the phylogenetic analysis, which are consistent with the intron-exon and conserved motif analyses. In addition, we identified five segmental duplication events, implying that the segmental duplications might be a crucial role in the expansion of the PHD-finger gene family in pear. The microsynteny analysis of five Rosaceae species showed that there were independent duplication events in addition to the genome-wide duplication of the pear genome. Subsequently, ten expressed PHD-finger genes of pear fruit were identified using qRT-PCR, and one of these genes, PbPHD10, was identified as an important candidate gene for the regulation of lignin synthesis. Our research provides useful information for the further analysis of the function of PHD-finger gene family in pear.
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31
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Rapid regulatory evolution of a nonrecombining autosome linked to divergent behavioral phenotypes. Proc Natl Acad Sci U S A 2018; 115:2794-2799. [PMID: 29483264 PMCID: PMC5856536 DOI: 10.1073/pnas.1717721115] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
In the white-throated sparrow (Zonotrichia albicollis), the second chromosome bears a striking resemblance to sex chromosomes. First, within each breeding pair of birds, one bird is homozygous for the standard arrangement of the chromosome (ZAL2/ZAL2) and its mate is heterozygous for a different version (ZAL2/ZAL2m). Second, recombination is profoundly suppressed between the two versions, leading to genetic differentiation between them. Third, the ZAL2m version is linked with phenotypic traits, such as bright plumage, high aggression, and low parental behavior, which are usually associated with males. These similarities to sex chromosomes suggest that the evolutionary mechanisms that shape sex chromosomes, in particular genetic degeneration of the heterogametic version due to the suppression of recombination, are likely important in this system as well. Here, we investigated patterns of protein sequence evolution and gene expression evolution between the ZAL2 and ZAL2m chromosomes by whole-genome sequencing and transcriptome analyses. Patterns of protein evolution exhibited only weak signals of genetic degeneration, and few genes harbored signatures of positive selection. We found substantial evidence of transcriptome evolution, such as significant expression divergence between ZAL2 and ZAL2m alleles and signatures of dosage compensation for highly expressed genes. These results suggest that, early in the evolution of heteromorphic chromosomes, gene expression divergence and dosage compensation can prevail before large-scale genetic degeneration. Our results show further that suppression of recombination between heteromorphic chromosomes can lead to the evolution of alternative (sex-like) behavioral phenotypes before substantial genetic degeneration.
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32
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Naqvi S, Bellott DW, Lin KS, Page DC. Conserved microRNA targeting reveals preexisting gene dosage sensitivities that shaped amniote sex chromosome evolution. Genome Res 2018; 28:474-483. [PMID: 29449410 PMCID: PMC5880238 DOI: 10.1101/gr.230433.117] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Accepted: 02/06/2018] [Indexed: 02/02/2023]
Abstract
Mammalian X and Y Chromosomes evolved from an ordinary autosomal pair. Genetic decay of the Y led to X Chromosome inactivation (XCI) in females, but some Y-linked genes were retained during the course of sex chromosome evolution, and many X-linked genes did not become subject to XCI. We reconstructed gene-by-gene dosage sensitivities on the ancestral autosomes through phylogenetic analysis of microRNA (miRNA) target sites and compared these preexisting characteristics to the current status of Y-linked and X-linked genes in mammals. Preexisting heterogeneities in dosage sensitivity, manifesting as differences in the extent of miRNA-mediated repression, predicted either the retention of a Y homolog or the acquisition of XCI following Y gene decay. Analogous heterogeneities among avian Z-linked genes predicted either the retention of a W homolog or gene-specific dosage compensation following W gene decay. Genome-wide analyses of human copy number variation indicate that these heterogeneities consisted of sensitivity to both increases and decreases in dosage. We propose a model of XY/ZW evolution incorporating such preexisting dosage sensitivities in determining the evolutionary fates of individual genes. Our findings thus provide a more complete view of the role of dosage sensitivity in shaping the mammalian and avian sex chromosomes and reveal an important role for post-transcriptional regulatory sequences (miRNA target sites) in sex chromosome evolution.
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Affiliation(s)
- Sahin Naqvi
- Whitehead Institute, Cambridge, Massachusetts 02142, USA.,Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | | | - Kathy S Lin
- Whitehead Institute, Cambridge, Massachusetts 02142, USA.,Program in Computational and Systems Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - David C Page
- Whitehead Institute, Cambridge, Massachusetts 02142, USA.,Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.,Howard Hughes Medical Institute, Whitehead Institute, Cambridge, Massachusetts 02142, USA
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33
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Xu J, Peng X, Chen Y, Zhang Y, Ma Q, Liang L, Carter AC, Lu X, Wu CI. Free-living human cells reconfigure their chromosomes in the evolution back to uni-cellularity. eLife 2017; 6. [PMID: 29251591 PMCID: PMC5734875 DOI: 10.7554/elife.28070] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Accepted: 10/28/2017] [Indexed: 01/06/2023] Open
Abstract
Cells of multi-cellular organisms evolve toward uni-cellularity in the form of cancer and, if humans intervene, continue to evolve in cell culture. During this process, gene dosage relationships may evolve in novel ways to cope with the new environment and may regress back to the ancestral uni-cellular state. In this context, the evolution of sex chromosomes vis-a-vis autosomes is of particular interest. Here, we report the chromosomal evolution in ~ 600 cancer cell lines. Many of them jettisoned either Y or the inactive X; thus, free-living male and female cells converge by becoming ‘de-sexualized’. Surprisingly, the active X often doubled, accompanied by the addition of one haploid complement of autosomes, leading to an X:A ratio of 2:3 from the extant ratio of 1:2. Theoretical modeling of the frequency distribution of X:A karyotypes suggests that the 2:3 ratio confers a higher fitness and may reflect aspects of sex chromosome evolution. Multicellular life relies on a group of cells working together for a common interest. To study these cells, researchers take them out of the organism and grow them in the laboratory. Instead of growing as part of organs and tissues, the cells normally have a free-living lifestyle. Because multicellular life evolved from single-celled organisms, laboratory-grown cells can be considered as life forms that are evolving backward from a multicellular to a single-celled existence. Normally, the cells that make up most of the tissues in the human body have 22 pairs of chromosomes known as autosomes and a pair of sex chromosomes. The cells of women have two X sex chromosomes, one of which is inactive, while those of men have one X and one Y chromosome. However, free-living single cells do not need to distinguish between male and female cells. Xu, Peng, Chen et al. have now studied the chromosomes of cancer cells taken from over 600 people and grown in the laboratory. As the cells evolved in response to their free-living lifestyle, they became ‘de-sexualized’; male cells lost their Y chromosome, while female cells abandoned their inactive X chromosome. The cells then evolved toward a new state in which they possessed two active X chromosomes and three sets of autosomes. This new configuration suggests that the current X chromosome to autosome ratio may not be optimal for fitness and hence sheds some light on how mammalian sex chromosomes evolved. It is currently thought that as cancerous tumors grow, their cells evolve to favor their own interests over the common interests of the rest of the organism. In this way, they develop characteristics more like those of single cells. Further research is therefore needed to investigate whether changes occur to the chromosomes of cancer cells growing within the body, and whether this gives them an advantage over normal cells.
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Affiliation(s)
- Jin Xu
- Key Laboratory of Genomic and Precision Medicine, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing, China
| | - Xinxin Peng
- Key Laboratory of Genomic and Precision Medicine, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing, China
| | - Yuxin Chen
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-Sen University, Guangzhou, China
| | - Yuezheng Zhang
- Key Laboratory of Genomic and Precision Medicine, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing, China
| | - Qin Ma
- Key Laboratory of Genomic and Precision Medicine, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Liang Liang
- Key Laboratory of Genomic and Precision Medicine, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Ava C Carter
- Center for Personal Dynamic Regulomes, Stanford University School of Medicine, Stanford, United States
| | - Xuemei Lu
- Key Laboratory of Genomic and Precision Medicine, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China.,CAS Center for Excellence in Animal Evolution and Genetics, Chinese Academy of Sciences, Kunming, China
| | - Chung-I Wu
- Key Laboratory of Genomic and Precision Medicine, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing, China.,State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-Sen University, Guangzhou, China.,Department of Ecology and Evolution, University of Chicago, Chicago, United States
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34
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Marin R, Cortez D, Lamanna F, Pradeepa MM, Leushkin E, Julien P, Liechti A, Halbert J, Brüning T, Mössinger K, Trefzer T, Conrad C, Kerver HN, Wade J, Tschopp P, Kaessmann H. Convergent origination of a Drosophila-like dosage compensation mechanism in a reptile lineage. Genome Res 2017; 27:1974-1987. [PMID: 29133310 PMCID: PMC5741051 DOI: 10.1101/gr.223727.117] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Accepted: 10/23/2017] [Indexed: 01/01/2023]
Abstract
Sex chromosomes differentiated from different ancestral autosomes in various vertebrate lineages. Here, we trace the functional evolution of the XY Chromosomes of the green anole lizard (Anolis carolinensis), on the basis of extensive high-throughput genome, transcriptome and histone modification sequencing data and revisit dosage compensation evolution in representative mammals and birds with substantial new expression data. Our analyses show that Anolis sex chromosomes represent an ancient XY system that originated at least ≈160 million years ago in the ancestor of Iguania lizards, shortly after the separation from the snake lineage. The age of this system approximately coincides with the ages of the avian and two mammalian sex chromosomes systems. To compensate for the almost complete Y Chromosome degeneration, X-linked genes have become twofold up-regulated, restoring ancestral expression levels. The highly efficient dosage compensation mechanism of Anolis represents the only vertebrate case identified so far to fully support Ohno's original dosage compensation hypothesis. Further analyses reveal that X up-regulation occurs only in males and is mediated by a male-specific chromatin machinery that leads to global hyperacetylation of histone H4 at lysine 16 specifically on the X Chromosome. The green anole dosage compensation mechanism is highly reminiscent of that of the fruit fly, Drosophila melanogaster. Altogether, our work unveils the convergent emergence of a Drosophila-like dosage compensation mechanism in an ancient reptilian sex chromosome system and highlights that the evolutionary pressures imposed by sex chromosome dosage reductions in different amniotes were resolved in fundamentally different ways.
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Affiliation(s)
- Ray Marin
- Center for Integrative Genomics, University of Lausanne, CH-1015 Lausanne, Switzerland.,Swiss Institute of Bioinformatics, CH-1015 Lausanne, Switzerland
| | - Diego Cortez
- Center for Genomic Sciences, UNAM, CP62210 Cuernavaca, Mexico
| | - Francesco Lamanna
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, D-69120 Heidelberg, Germany
| | - Madapura M Pradeepa
- School of Biological Sciences, University of Essex, Colchester CO4 3SQ, United Kingdom
| | - Evgeny Leushkin
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, D-69120 Heidelberg, Germany
| | - Philippe Julien
- EMBL/CRG Systems Biology Research Unit, Centre for Genomic Regulation, 08003 Barcelona, Spain
| | - Angélica Liechti
- Center for Integrative Genomics, University of Lausanne, CH-1015 Lausanne, Switzerland
| | - Jean Halbert
- Center for Integrative Genomics, University of Lausanne, CH-1015 Lausanne, Switzerland
| | - Thoomke Brüning
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, D-69120 Heidelberg, Germany
| | - Katharina Mössinger
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, D-69120 Heidelberg, Germany
| | - Timo Trefzer
- Department of Theoretical Bioinformatics, German Cancer Research Center/BioQuant, D-69120 Heidelberg, Germany
| | - Christian Conrad
- Department of Theoretical Bioinformatics, German Cancer Research Center/BioQuant, D-69120 Heidelberg, Germany
| | - Halie N Kerver
- Neuroscience Program, Michigan State University, East Lansing, Michigan 48824, USA
| | - Juli Wade
- Neuroscience Program, Michigan State University, East Lansing, Michigan 48824, USA.,Department of Psychology, Michigan State University, East Lansing, Michigan 48824, USA
| | - Patrick Tschopp
- Institute of Zoology, University of Basel, 4051 Basel, Switzerland
| | - Henrik Kaessmann
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, D-69120 Heidelberg, Germany
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35
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Röpke A, Tüttelmann F. MECHANISMS IN ENDOCRINOLOGY: Aberrations of the X chromosome as cause of male infertility. Eur J Endocrinol 2017; 177:R249-R259. [PMID: 28611019 DOI: 10.1530/eje-17-0246] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Revised: 05/22/2017] [Accepted: 06/13/2017] [Indexed: 11/08/2022]
Abstract
Male infertility is most commonly caused by spermatogenetic failure, clinically noted as oligo- or a-zoospermia. Today, in approximately 20% of azoospermic patients, a causal genetic defect can be identified. The most frequent genetic causes of azoospermia (or severe oligozoospermia) are Klinefelter syndrome (47,XXY), structural chromosomal abnormalities and Y-chromosomal microdeletions. Consistent with Ohno's law, the human X chromosome is the most stable of all the chromosomes, but contrary to Ohno's law, the X chromosome is loaded with regions of acquired, rapidly evolving genes, which are of special interest because they are predominantly expressed in the testis. Therefore, it is not surprising that the X chromosome, considered as the female counterpart of the male-associated Y chromosome, may actually play an essential role in male infertility and sperm production. This is supported by the recent description of a significantly increased copy number variation (CNV) burden on both sex chromosomes in infertile men and point mutations in X-chromosomal genes responsible for male infertility. Thus, the X chromosome seems to be frequently affected in infertile male patients. Four principal X-chromosomal aberrations have been identified so far: (1) aneuploidy of the X chromosome as found in Klinefelter syndrome (47,XXY or mosaicism for additional X chromosomes). (2) Translocations involving the X chromosome, e.g. nonsyndromic 46,XX testicular disorders of sex development (XX-male syndrome) or X-autosome translocations. (3) CNVs affecting the X chromosome. (4) Point mutations disrupting X-chromosomal genes. All these are reviewed herein and assessed concerning their importance for the clinical routine diagnostic workup of the infertile male as well as their potential to shape research on spermatogenic failure in the next years.
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36
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Gu L, Walters JR, Knipple DC. Conserved Patterns of Sex Chromosome Dosage Compensation in the Lepidoptera (WZ/ZZ): Insights from a Moth Neo-Z Chromosome. Genome Biol Evol 2017; 9:802-816. [PMID: 28338816 PMCID: PMC5381563 DOI: 10.1093/gbe/evx039] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/01/2017] [Indexed: 02/07/2023] Open
Abstract
Where previously described, patterns of sex chromosome dosage compensation in the Lepidoptera (moths and butterflies) have several unusual characteristics. Other female-heterogametic (ZW/ZZ) species exhibit female Z-linked expression that is reduced compared with autosomal expression and male Z expression. In the Lepidoptera, however, Z expression typically appears balanced between sexes but overall reduced relative to autosomal expression, that is Z ≈ ZZ < AA. This pattern is not easily reconciled with theoretical expectations for the evolution of sex chromosome dosage compensation. Moreover, conflicting results linger due to discrepancies in data analyses and tissues sampled among lepidopterans. To address these issues, we performed RNA-seq to analyze sex chromosome dosage compensation in the codling moth, Cydia pomonella, which is a species from the earliest diverging lepidopteran lineage yet examined for dosage compensation and has a neo-Z chromosome resulting from an ancient Z:autosome fusion. While supported by intraspecific analyses, the Z ≈ ZZ < AA pattern was further evidenced by comparative study using autosomal orthologs of C. pomonella neo-Z genes in outgroup species. In contrast, dosage compensation appears to be absent in reproductive tissues. We thus argue that inclusion of reproductive tissues may explain the incongruence from a prior study on another moth species and that patterns of dosage compensation are likely conserved in the Lepidoptera. Notably, this pattern appears convergent with patterns in eutherian mammals (X ≈ XX < AA). Overall, our results contribute to the notion that the Lepidoptera present challenges both to classical theories regarding the evolution of sex chromosome dosage compensation and the emerging view of the association of dosage compensation with sexual heterogamety.
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Affiliation(s)
- Liuqi Gu
- Department of Entomology, Cornell University, Geneva, NY
| | - James R Walters
- Department of Ecology & Evolutionary Biology, The University of Kansas, Lawrence, KS
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37
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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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38
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Gianazza E, Miller I, Guerrini U, Palazzolo L, Parravicini C, Eberini I. Gender proteomics I. Which proteins in non-sexual organs. J Proteomics 2017; 178:7-17. [PMID: 28988882 DOI: 10.1016/j.jprot.2017.10.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Revised: 09/26/2017] [Accepted: 10/04/2017] [Indexed: 12/15/2022]
Abstract
Differences related to gender have long been neglected but recent investigations show that they are widespread and may be recognized with all types of omics approaches, both in tissues and in biological fluids. Our review compiles evidence collected with proteomics techniques in our species, mainly focusing on baseline parameters in non-sexual organs in healthy men and women. Data from human specimens had to be replaced with information from other mammals every time invasive procedures of sample procurement were involved. SIGNIFICANCE As our knowledge, and the methods to build it, get refined, gender differences need to receive more and more attention, as they influence the outcome of all aspects in lifestyle, including diet, exercise and environmental factors. In turn this background modulates a differential susceptibility to some disease, or a different pathogenetic mechanism, depending on gender, and a different response to pharmacological therapy. Preparing this review we meant to raise awareness about the gender issue. We anticipate that more and more often, in the future, separate evaluations will be carried out on male and female subjects as an alternative - and an upgrade - to the current approach of reference and test groups being 'matched for age and sex'.
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Affiliation(s)
- Elisabetta Gianazza
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Via Balzaretti 9, I-20133 Milano, Italy.
| | - Ingrid Miller
- Institut für Medizinische Biochemie, Veterinärmedizinische Universität Wien, Veterinärplatz 1, A-1210 Wien, Austria
| | - Uliano Guerrini
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Via Balzaretti 9, I-20133 Milano, Italy
| | - Luca Palazzolo
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Via Balzaretti 9, I-20133 Milano, Italy
| | - Chiara Parravicini
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Via Balzaretti 9, I-20133 Milano, Italy
| | - Ivano Eberini
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Via Balzaretti 9, I-20133 Milano, Italy
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39
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Mahajan S, Bachtrog D. Convergent evolution of Y chromosome gene content in flies. Nat Commun 2017; 8:785. [PMID: 28978907 PMCID: PMC5627270 DOI: 10.1038/s41467-017-00653-x] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Accepted: 07/18/2017] [Indexed: 11/25/2022] Open
Abstract
Sex-chromosomes have formed repeatedly across Diptera from ordinary autosomes, and X-chromosomes mostly conserve their ancestral genes. Y-chromosomes are characterized by abundant gene-loss and an accumulation of repetitive DNA, yet the nature of the gene repertoire of fly Y-chromosomes is largely unknown. Here we trace gene-content evolution of Y-chromosomes across 22 Diptera species, using a subtraction pipeline that infers Y genes from male and female genome, and transcriptome data. Few genes remain on old Y-chromosomes, but the number of inferred Y-genes varies substantially between species. Young Y-chromosomes still show clear evidence of their autosomal origins, but most genes on old Y-chromosomes are not simply remnants of genes originally present on the proto-sex-chromosome that escaped degeneration, but instead were recruited secondarily from autosomes. Despite almost no overlap in Y-linked gene content in different species with independently formed sex-chromosomes, we find that Y-linked genes have evolved convergent gene functions associated with testis expression. Thus, male-specific selection appears as a dominant force shaping gene-content evolution of Y-chromosomes across fly species. While X-chromosome gene content tends to be conserved, Y-chromosome evolution is dynamic and difficult to reconstruct. Here, Mahajan and Bachtrog use a subtraction pipeline to identify Y-linked genes in 22 Diptera species, revealing patterns of Y-chromosome gene-content evolution.
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Affiliation(s)
- Shivani Mahajan
- Department of Integrative Biology, University of California Berkeley, Berkeley, California, 94720, USA
| | - Doris Bachtrog
- Department of Integrative Biology, University of California Berkeley, Berkeley, California, 94720, USA.
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Huylmans AK, Macon A, Vicoso B. Global Dosage Compensation Is Ubiquitous in Lepidoptera, but Counteracted by the Masculinization of the Z Chromosome. Mol Biol Evol 2017; 34:2637-2649. [PMID: 28957502 PMCID: PMC5850747 DOI: 10.1093/molbev/msx190] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
While chromosome-wide dosage compensation of the X chromosome has been found in many species, studies in ZW clades have indicated that compensation of the Z is more localized and/or incomplete. In the ZW Lepidoptera, some species show complete compensation of the Z chromosome, while others lack full equalization, but what drives these inconsistencies is unclear. Here, we compare patterns of male and female gene expression on the Z chromosome of two closely related butterfly species, Papilio xuthus and Papilio machaon, and in multiple tissues of two moths species, Plodia interpunctella and Bombyx mori, which were previously found to differ in the extent to which they equalize Z-linked gene expression between the sexes. We find that, while some species and tissues seem to have incomplete dosage compensation, this is in fact due to the accumulation of male-biased genes and the depletion of female-biased genes on the Z chromosome. Once this is accounted for, the Z chromosome is fully compensated in all four species, through the up-regulation of Z expression in females and in some cases additional down-regulation in males. We further find that both sex-biased genes and Z-linked genes have increased rates of expression divergence in this clade, and that this can lead to fast shifts in patterns of gene expression even between closely related species. Taken together, these results show that the uneven distribution of sex-biased genes on sex chromosomes can confound conclusions about dosage compensation and that Z chromosome-wide dosage compensation is not only possible but ubiquitous among Lepidoptera.
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Affiliation(s)
| | - Ariana Macon
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - Beatriz Vicoso
- Institute of Science and Technology Austria, Klosterneuburg, Austria
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41
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Sex chromosomes drive gene expression and regulatory dimorphisms in mouse embryonic stem cells. Biol Sex Differ 2017; 8:28. [PMID: 28818098 PMCID: PMC5561606 DOI: 10.1186/s13293-017-0150-x] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Accepted: 08/10/2017] [Indexed: 01/21/2023] Open
Abstract
BACKGROUND Pre-implantation embryos exhibit sexual dimorphisms in both primates and rodents. To determine whether these differences reflected sex-biased expression patterns, we generated transcriptome profiles for six 40,XX, six 40,XY, and two 39,X mouse embryonic stem (ES) cells by RNA sequencing. RESULTS We found hundreds of coding and non-coding RNAs that were differentially expressed between male and female cells. Surprisingly, the majority of these were autosomal and included RNA encoding transcription and epigenetic and chromatin remodeling factors. We showed differential Prdm14-responsive enhancer activity in male and female cells, correlating with the sex-specific levels of Prdm14 expression. This is the first time sex-specific enhancer activity in ES cells has been reported. Evaluation of X-linked gene expression patterns between our XX and XY lines revealed four distinct categories: (1) genes showing 2-fold greater expression in the female cells; (2) a set of genes with expression levels well above 2-fold in female cells; (3) genes with equivalent RNA levels in male and female cells; and strikingly, (4) a small number of genes with higher expression in the XY lines. Further evaluation of autosomal gene expression revealed differential expression of imprinted loci, despite appropriate parent-of-origin patterns. The 39,X lines aligned closely with the XY cells and provided insights into potential regulation of genes associated with Turner syndrome in humans. Moreover, inclusion of the 39,X lines permitted three-way comparisons, delineating X and Y chromosome-dependent patterns. CONCLUSIONS Overall, our results support the role of the sex chromosomes in establishing sex-specific networks early in embryonic development and provide insights into effects of sex chromosome aneuploidies originating at those stages.
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42
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Dosage compensation in the process of inactivation/reactivation during both germ cell development and early embryogenesis in mouse. Sci Rep 2017. [PMID: 28623283 PMCID: PMC5473838 DOI: 10.1038/s41598-017-03829-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Ohno proposed that dosage compensation in mammals evolved as a two-step mechanism involving X-inactivation and X-upregulation. While X-inactivation is well characterized, it remains to further analysis whether upregulation of the single activated X chromosome in mammals occurs. We obtained RNA-seq data, including single-cell RNA-seq data, from cells undergoing inactivation/reactivation in both germ cell development and early embryogenesis stages in mouse and calculated the X: A ratio from the gene expression. Our results showed that the X: A ratio is always 1, regardless of the number of X chromosomes being transcribed for expressed genes. Furthermore, the single-cell RNA-seq data across individual cells of mouse preimplantation embryos of mixed backgrounds indicated that strain-specific SNPs could be used to distinguish transcription from maternal and paternal chromosomes and further showed that when the paternal was inactivated, the average gene dosage of the active maternal X chromosome was increased to restore the balance between the X chromosome and autosomes. In conclusion, our analysis of RNA-seq data (particularly single-cell RNA-seq) from cells undergoing the process of inactivation/reactivation provides direct evidence that the average gene dosage of the single active X chromosome is upregulated to achieve a similar level to that of two active X chromosomes and autosomes present in two copies.
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43
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Richard G, Legeai F, Prunier-Leterme N, Bretaudeau A, Tagu D, Jaquiéry J, Le Trionnaire G. Dosage compensation and sex-specific epigenetic landscape of the X chromosome in the pea aphid. Epigenetics Chromatin 2017. [PMID: 28638443 PMCID: PMC5471693 DOI: 10.1186/s13072-017-0137-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Background Heterogametic species display a differential number of sex chromosomes resulting in imbalanced transcription levels for these chromosomes between males and females. To correct this disequilibrium, dosage compensation mechanisms involving gene expression and chromatin accessibility regulations have emerged throughout evolution. In insects, these mechanisms have been extensively characterized only in Drosophila but not in insects of agronomical importance. Aphids are indeed major pests of a wide range of crops. Their remarkable ability to switch from asexual to sexual reproduction during their life cycle largely explains the economic losses they can cause. As heterogametic insects, male aphids are X0, while females (asexual and sexual) are XX. Results Here, we analyzed transcriptomic and open chromatin data obtained from whole male and female individuals to evaluate the putative existence of a dosage compensation mechanism involving differential chromatin accessibility of the pea aphid’s X chromosome. Transcriptomic analyses first showed X/AA and XX/AA expression ratios for expressed genes close to 1 in males and females, respectively, suggesting dosage compensation in the pea aphid. Analyses of open chromatin data obtained by Formaldehyde-Assisted Isolation of Regulatory Elements (FAIRE-seq) revealed a X chromosome chromatin accessibility globally and significantly higher in males than in females, while autosomes’ chromatin accessibility is similar between sexes. Moreover, chromatin environment of X-linked genes displaying similar expression levels in males and females—and thus likely to be compensated—is significantly more accessible in males. Conclusions Our results suggest the existence of an underlying epigenetic mechanism enhancing the X chromosome chromatin accessibility in males to allow X-linked gene dose correction between sexes in the pea aphid, similar to Drosophila. Our study gives new evidence into the comprehension of dosage compensation in link with chromatin biology in insects and newly in a major crop pest, taking benefits from both transcriptomic and open chromatin data. Electronic supplementary material The online version of this article (doi:10.1186/s13072-017-0137-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Gautier Richard
- EGI, UMR 1349, INRA, Institut de Génétique, Environnement et Protection des Plantes (IGEPP), Domaine de la Motte, BP 35327, Le Rheu, France
| | - Fabrice Legeai
- BIPAA, UMR 1349, INRA, Institut de Génétique, Environnement et Protection des Plantes (IGEPP), Campus Beaulieu, Rennes, France.,Genscale, INRIA, IRISA, Campus Beaulieu, Rennes, France
| | - Nathalie Prunier-Leterme
- EGI, UMR 1349, INRA, Institut de Génétique, Environnement et Protection des Plantes (IGEPP), Domaine de la Motte, BP 35327, Le Rheu, France
| | - Anthony Bretaudeau
- BIPAA, UMR 1349, INRA, Institut de Génétique, Environnement et Protection des Plantes (IGEPP), Campus Beaulieu, Rennes, France.,Genouest, INRIA, IRISA, Campus Beaulieu, Rennes, France
| | - Denis Tagu
- EGI, UMR 1349, INRA, Institut de Génétique, Environnement et Protection des Plantes (IGEPP), Domaine de la Motte, BP 35327, Le Rheu, France
| | - Julie Jaquiéry
- CNRS, UMR 6553, EcoBio, University of Rennes 1, 35042 Rennes, France
| | - Gaël Le Trionnaire
- EGI, UMR 1349, INRA, Institut de Génétique, Environnement et Protection des Plantes (IGEPP), Domaine de la Motte, BP 35327, Le Rheu, France
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Albritton SE, Kranz AL, Winterkorn LH, Street LA, Ercan S. Cooperation between a hierarchical set of recruitment sites targets the X chromosome for dosage compensation. eLife 2017; 6. [PMID: 28562241 PMCID: PMC5451215 DOI: 10.7554/elife.23645] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Accepted: 05/02/2017] [Indexed: 12/17/2022] Open
Abstract
In many organisms, it remains unclear how X chromosomes are specified for dosage compensation, since DNA sequence motifs shown to be important for dosage compensation complex (DCC) recruitment are themselves not X-specific. Here, we addressed this problem in C. elegans. We found that the DCC recruiter, SDC-2, is required to maintain open chromatin at a small number of primary DCC recruitment sites, whose sequence and genomic context are X-specific. Along the X, primary recruitment sites are interspersed with secondary sites, whose function is X-dependent. A secondary site can ectopically recruit the DCC when additional recruitment sites are inserted either in tandem or at a distance (>30 kb). Deletion of a recruitment site on the X results in reduced DCC binding across several megabases surrounded by topologically associating domain (TAD) boundaries. Our work elucidates that hierarchy and long-distance cooperativity between gene-regulatory elements target a single chromosome for regulation. DOI:http://dx.doi.org/10.7554/eLife.23645.001 The DNA inside living cells is organized in structures called chromosomes. In many animals, females have two X chromosomes, whereas males have only one. To ensure that females do not end up with a double dose of the proteins encoded by the genes on the X chromosome, animals use a process called dosage compensation to correct this imbalance. The mechanisms underlying this process vary between species, but they typically involve a regulatory complex that binds to the X chromosomes of one sex to modify gene expression. Caenorhabditis elegans, for example, is a species of nematode worm in which individuals with two X chromosomes are hermaphrodites and those with one X chromosome are males. In C. elegans, a regulatory complex, called the dosage compensation complex, attaches to both X chromosomes of a hermaphrodite, and reduces the expression of the genes on each by half to match the level seen in the males. Previous research has shown that short DNA sequences, known as motifs, recruit the dosage compensation complex to the X chromosomes. However, these sequences are also found on the other chromosomes and, until now, it was not known why the complex was only recruited to the X chromosomes. Albritton et al. now show the X chromosomes have a ‘hierarchical’ recruitment system. A few sites on the X chromosomes contain clusters of a specific DNA motif, which initiate the process and attract the dosage compensation complex more strongly than other sites. These ‘strong’ recruitment sites are placed across the length of the X chromosomes and cooperate with several ‘weaker’ ones located in between. This way, multiple recruitment sites can cooperate over a long distance, while non-sex chromosomes, which have only one or two stronger recruitment sites, do not have thisadvantage. Hierarchy and cooperativity may be general features of gene expression, in which proteins are targeted to chromosomes without the need for having specific motifs at every recruitment site. The way DNA sequences are distributed across the genome may give us clues about their role. Thus, knowing how genomes are structured will help us identify disrupted areas in diseases such as cancer. DOI:http://dx.doi.org/10.7554/eLife.23645.002
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Affiliation(s)
- Sarah Elizabeth Albritton
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, United States
| | - Anna-Lena Kranz
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, United States
| | - Lara Heermans Winterkorn
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, United States
| | - Lena Annika Street
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, United States
| | - Sevinc Ercan
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, United States
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45
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Chandler CH. When and why does sex chromosome dosage compensation evolve? Ann N Y Acad Sci 2017; 1389:37-51. [DOI: 10.1111/nyas.13307] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2016] [Revised: 11/21/2016] [Accepted: 12/01/2016] [Indexed: 01/07/2023]
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46
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Wang M, Lin F, Xing K, Liu L. Random X-chromosome inactivation dynamics in vivo by single-cell RNA sequencing. BMC Genomics 2017; 18:90. [PMID: 28095777 PMCID: PMC5240438 DOI: 10.1186/s12864-016-3466-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Accepted: 12/23/2016] [Indexed: 12/05/2022] Open
Abstract
Background Random X-chromosome inactivation (rXCI) is important for the maintenance of normal somatic cell functions in female eutherian mammals. The dynamics of X-chromosome inactivation initiation has been widely studied by assessing embryonic stem cell differentiation in vitro. To investigate the phenomenon in vivo, we applied RNA sequencing to single cells from female embryos obtained from a natural intercrossing of two genetically distant mouse strains. Instead of artificially assigning the parental origin of the inactive X chromosome, the inactive X chromosomes in this study were randomly selected from the natural developmental periods and thus included both paternal and maternal origins. Results The rXCI stages of single cells from the same developmental stage showed heterogeneity. The high resolution of the rXCI dynamics was exhibited. The inactivation orders of X chromosomal genes were determined by their functions, expression levels, and locations; generally, the inactivation order did not exhibit a parental origin preference. New escape genes were identified. Ohno’s hypothesis of dosage compensation was refuted by our post-implantation stage data. Conclusions We found the inactivation orders of X chromosomal genes were determined by their own properties. Generally, the inactivation order did not exhibit a parental origin preference. It provided insights into the gene silencing dynamics during rXCI in vivo. Electronic supplementary material The online version of this article (doi:10.1186/s12864-016-3466-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Menghan Wang
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, People's Republic of China
| | - Fangqin Lin
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, People's Republic of China
| | - Ke Xing
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, People's Republic of China
| | - Li Liu
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, People's Republic of China.
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47
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Chen X, Zhang J. The X to Autosome Expression Ratio in Haploid and Diploid Human Embryonic Stem Cells. Mol Biol Evol 2016; 33:3104-3107. [PMID: 27593371 DOI: 10.1093/molbev/msw187] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Ohno proposed that the expression levels of X-linked genes have been doubled to compensate the degeneration of Y-linked homologs during the evolution of mammalian sex chromosomes, but RNA sequencing in human somatic tissues showed no such upregulation for the vast majority of X-linked genes. Here we report that the X to autosome expression ratio equals ∼1 in haploid human parthenogenetic embryonic stem (pES) cells and ∼0.5 in diploidized pES cells, both with one active X chromosome. Although we confirmed the upregulation of ∼5% of X-linked genes encoding members of large protein complexes in diploids, these genes are also upregulated in haploids, breaking the otherwise balanced dosage. These findings argue against Ohno's hypothesis for both haploid and diploid cells and demonstrate that, at least in humans, precise gene regulation for dosage balance, even for members of large protein complexes, is much less critical than is commonly thought.
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Affiliation(s)
- Xiaoshu Chen
- Human Genome Research Institute and Deparment of Medical Genetics, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China.,Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI
| | - Jianzhi Zhang
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI
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48
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Mulugeta E, Wassenaar E, Sleddens-Linkels E, van IJcken WFJ, Heard E, Grootegoed JA, Just W, Gribnau J, Baarends WM. Genomes of Ellobius species provide insight into the evolutionary dynamics of mammalian sex chromosomes. Genome Res 2016; 26:1202-10. [PMID: 27510564 PMCID: PMC5052041 DOI: 10.1101/gr.201665.115] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Accepted: 07/11/2016] [Indexed: 11/24/2022]
Abstract
The X and Y sex chromosomes of placental mammals show hallmarks of a tumultuous evolutionary past. The X Chromosome has a rich and conserved gene content, while the Y Chromosome has lost most of its genes. In the Transcaucasian mole vole Ellobius lutescens, the Y Chromosome including Sry has been lost, and both females and males have a 17,X diploid karyotype. Similarly, the closely related Ellobius talpinus, has a 54,XX karyotype in both females and males. Here, we report the sequencing and assembly of the E. lutescens and E. talpinus genomes. The results indicate that the loss of the Y Chromosome in E. lutescens and E. talpinus occurred in two independent events. Four functional homologs of mouse Y-Chromosomal genes were detected in both female and male E. lutescens, of which three were also detected in the E. talpinus genome. One of these is Eif2s3y, known as the only Y-derived gene that is crucial for successful male meiosis. Female and male E. lutescens can carry one and the same X Chromosome with a largely conserved gene content, including all genes known to function in X Chromosome inactivation. The availability of the genomes of these mole vole species provides unique models to study the dynamics of sex chromosome evolution.
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Affiliation(s)
- Eskeatnaf Mulugeta
- Department of Developmental Biology, Erasmus MC, 3015CN, Rotterdam, The Netherlands; Institut Curie, Genetics and Developmental Biology Unit, 75248, Paris, France
| | - Evelyne Wassenaar
- Department of Developmental Biology, Erasmus MC, 3015CN, Rotterdam, The Netherlands
| | | | | | - Edith Heard
- Institut Curie, Genetics and Developmental Biology Unit, 75248, Paris, France
| | - J Anton Grootegoed
- Department of Developmental Biology, Erasmus MC, 3015CN, Rotterdam, The Netherlands
| | - Walter Just
- Institute of Human Genetics, University of Ulm, 89081, Ulm, Germany
| | - Joost Gribnau
- Department of Developmental Biology, Erasmus MC, 3015CN, Rotterdam, The Netherlands
| | - Willy M Baarends
- Department of Developmental Biology, Erasmus MC, 3015CN, Rotterdam, The Netherlands
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49
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Dean R, Mank JE. Tissue Specificity and Sex-Specific Regulatory Variation Permit the Evolution of Sex-Biased Gene Expression. Am Nat 2016; 188:E74-84. [PMID: 27501094 DOI: 10.1086/687526] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Genetic correlations between males and females are often thought to constrain the evolution of sexual dimorphism. However, sexually dimorphic traits and the underlying sexually dimorphic gene expression patterns are often rapidly evolving. We explore this apparent paradox by measuring the genetic correlation in gene expression between males and females (Cmf) across broad evolutionary timescales, using two RNA-sequencing data sets spanning multiple populations and multiple species. We find that unbiased genes have higher Cmf than sex-biased genes, consistent with intersexual genetic correlations constraining the evolution of sexual dimorphism. However, we found that highly sex-biased genes (both male and female biased) also had higher tissue specificity, and unbiased genes had greater expression breadth, suggesting that pleiotropy may constrain the breakdown of intersexual genetic correlations. Finally, we show that genes with high Cmf showed some degree of sex-specific changes in gene expression in males and females. Together, our results suggest that genetic correlations between males and females may be less important in constraining the evolution of sex-biased gene expression than pleiotropy. Sex-specific regulatory variation and tissue specificity may resolve the paradox of widespread sex bias within a largely shared genome.
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50
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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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