1
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Jalloh B, Lancaster CL, Rounds JC, Brown BE, Leung SW, Banerjee A, Morton DJ, Bienkowski RS, Fasken MB, Kremsky IJ, Tegowski M, Meyer K, Corbett A, Moberg K. The Drosophila Nab2 RNA binding protein inhibits m 6A methylation and male-specific splicing of Sex lethal transcript in female neuronal tissue. eLife 2023; 12:e64904. [PMID: 37458420 PMCID: PMC10351920 DOI: 10.7554/elife.64904] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2020] [Accepted: 06/23/2023] [Indexed: 07/20/2023] Open
Abstract
The Drosophila polyadenosine RNA binding protein Nab2, which is orthologous to a human protein lost in a form of inherited intellectual disability, controls adult locomotion, axon projection, dendritic arborization, and memory through a largely undefined set of target RNAs. Here, we show a specific role for Nab2 in regulating splicing of ~150 exons/introns in the head transcriptome and focus on retention of a male-specific exon in the sex determination factor Sex-lethal (Sxl) that is enriched in female neurons. Previous studies have revealed that this splicing event is regulated in females by N6-methyladenosine (m6A) modification by the Mettl3 complex. At a molecular level, Nab2 associates with Sxl pre-mRNA in neurons and limits Sxl m6A methylation at specific sites. In parallel, reducing expression of the Mettl3, Mettl3 complex components, or the m6A reader Ythdc1 rescues mutant phenotypes in Nab2 flies. Overall, these data identify Nab2 as an inhibitor of m6A methylation and imply significant overlap between Nab2 and Mettl3 regulated RNAs in neuronal tissue.
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Affiliation(s)
- Binta Jalloh
- Department of Biology, Emory UniversityAtlantaUnited States
- Department of Cell Biology Emory University School of MedicineAtlantaUnited States
- Graduate Program in Genetics and Molecular Biology, Emory UniversityAtlantaUnited States
| | - Carly L Lancaster
- Department of Biology, Emory UniversityAtlantaUnited States
- Department of Cell Biology Emory University School of MedicineAtlantaUnited States
- Graduate Program in Biochemistry, Cell and Developmental Biology, Emory UniversityAtlantaUnited States
| | - J Christopher Rounds
- Department of Biology, Emory UniversityAtlantaUnited States
- Department of Cell Biology Emory University School of MedicineAtlantaUnited States
- Graduate Program in Genetics and Molecular Biology, Emory UniversityAtlantaUnited States
| | - Brianna E Brown
- Department of Biology, Emory UniversityAtlantaUnited States
- Department of Cell Biology Emory University School of MedicineAtlantaUnited States
| | - Sara W Leung
- Department of Biology, Emory UniversityAtlantaUnited States
| | - Ayan Banerjee
- Department of Biology, Emory UniversityAtlantaUnited States
| | - Derrick J Morton
- Department of Biology, Emory UniversityAtlantaUnited States
- Emory Institutional Research and Academic Career Development Award (IRACDA), Fellowships in Research and Science Teaching (FIRST) Postdoctoral FellowshipAtlantaUnited States
| | - Rick S Bienkowski
- Department of Biology, Emory UniversityAtlantaUnited States
- Department of Cell Biology Emory University School of MedicineAtlantaUnited States
- Graduate Program in Genetics and Molecular Biology, Emory UniversityAtlantaUnited States
| | - Milo B Fasken
- Department of Biology, Emory UniversityAtlantaUnited States
| | | | - Matthew Tegowski
- Department of Biochemistry, Duke University School of MedicineDurhamUnited States
| | - Kate Meyer
- Department of Biochemistry, Duke University School of MedicineDurhamUnited States
- Department of Neurobiology, Duke University School of MedicineDurhamUnited States
| | - Anita Corbett
- Department of Biology, Emory UniversityAtlantaUnited States
| | - Ken Moberg
- Department of Cell Biology Emory University School of MedicineAtlantaUnited States
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2
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Nanni AV, Martinez N, Graze R, Morse A, Newman JRB, Jain V, Vlaho S, Signor S, Nuzhdin SV, Renne R, McIntyre LM. Sex-biased expression is associated with chromatin state in D. melanogaster and D. simulans. bioRxiv 2023:2023.01.13.523946. [PMID: 36711631 PMCID: PMC9882225 DOI: 10.1101/2023.01.13.523946] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
We propose a new model for the association of chromatin state and sex-bias in expression. We hypothesize enrichment of open chromatin in the sex where we see expression bias (OS) and closed chromatin in the opposite sex (CO). In this study of D. melanogaster and D. simulans head tissue, sex-bias in expression is associated with H3K4me3 (open mark) in males for male-biased genes and in females for female-biased genes in both species. Sex-bias in expression is also largely conserved in direction and magnitude between the two species on the X and autosomes. In male-biased orthologs, the sex-bias ratio is more divergent between species if both species have H3K27me2me3 marks in females compared to when either or neither species has H3K27me2me3 in females. H3K27me2me3 marks in females are associated with male-bias in expression on the autosomes in both species, but on the X only in D. melanogaster . In female-biased orthologs the relationship between the species for the sex-bias ratio is similar regardless of the H3K27me2me3 marks in males. Female-biased orthologs are more similar in the ratio of sex-bias than male-biased orthologs and there is an excess of male-bias in expression in orthologs that gain/lose sex-bias. There is an excess of male-bias in sex-limited expression in both species suggesting excess male-bias is due to rapid evolution between the species. The X chromosome has an enrichment in male-limited H3K4me3 in both species and an enrichment of sex-bias in expression compared to the autosomes.
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Affiliation(s)
- Adalena V Nanni
- Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, FL
- University of Florida Genetics Institute, University of Florida, Gainesville, FL, USA
| | - Natalie Martinez
- Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, FL
| | - Rita Graze
- Department of Biological Sciences, Auburn University, Auburn, AL, USA
| | - Alison Morse
- Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, FL
- University of Florida Genetics Institute, University of Florida, Gainesville, FL, USA
| | - Jeremy R B Newman
- University of Florida Genetics Institute, University of Florida, Gainesville, FL, USA
| | - Vaibhav Jain
- Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, FL
| | - Srna Vlaho
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, USA
| | - Sarah Signor
- Department of Biological Sciences, North Dakota State University, Fargo, ND, USA
| | - Sergey V Nuzhdin
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, USA
| | - Rolf Renne
- Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, FL
- University of Florida Genetics Institute, University of Florida, Gainesville, FL, USA
| | - Lauren M McIntyre
- Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, FL
- University of Florida Genetics Institute, University of Florida, Gainesville, FL, USA
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3
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Saccone G. A history of the genetic and molecular identification of genes and their functions controlling insect sex determination. Insect Biochem Mol Biol 2022; 151:103873. [PMID: 36400424 DOI: 10.1016/j.ibmb.2022.103873] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Revised: 11/01/2022] [Accepted: 11/02/2022] [Indexed: 06/16/2023]
Abstract
The genetics of the sex determination regulatory cascade in Drosophila melanogaster has a fascinating history, interlinked with the foundation of the Genetics discipline itself. The discovery that alternative splicing rather than differential transcription is the molecular mechanism underlying the upstream control of sex differences in the Drosophila model system was surprising. This notion is now fully integrated into the scientific canon, appearing in many genetics textbooks and online education resources. In the last three decades, it was a key reference point for starting evolutionary studies in other insect species by using homology-based approaches. This review will introduce a very brief history of Drosophila genetics. It will describe the genetic and molecular approaches applied for the identifying and cloning key genes involved in sex determination in Drosophila and in many other insect species. These comparative analyses led to supporting the idea that sex-determining pathways have evolved mainly by recruiting different upstream signals/genes while maintaining widely conserved intermediate and downstream regulatory genes. The review also provides examples of the link between technological advances and research achievements, to stimulate reflections on how science is produced. It aims to hopefully strengthen the related historical and conceptual knowledge of general readers of other disciplines and of younger geneticists, often focused on the latest technical-molecular approaches.
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Affiliation(s)
- Giuseppe Saccone
- Department of Biology, University of Naples Federico II, Via Cinthia 26, 80126, Naples, Italy.
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4
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Shevelyov YY, Ulianov SV, Gelfand MS, Belyakin SN, Razin SV. Dosage Compensation in Drosophila: Its Canonical and Non-Canonical Mechanisms. Int J Mol Sci 2022; 23:10976. [PMID: 36142884 DOI: 10.3390/ijms231810976] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 09/16/2022] [Accepted: 09/17/2022] [Indexed: 11/17/2022] Open
Abstract
Dosage compensation equalizes gene expression in a single male X chromosome with that in the pairs of autosomes and female X chromosomes. In the fruit fly Drosophila, canonical dosage compensation is implemented by the male-specific lethal (MSL) complex functioning in all male somatic cells. This complex contains acetyl transferase males absent on the first (MOF), which performs H4K16 hyperacetylation specifically in the male X chromosome, thus facilitating transcription of the X-linked genes. However, accumulating evidence points to an existence of additional, non-canonical dosage compensation mechanisms operating in somatic and germline cells. In this review, we discuss current advances in the understanding of both canonical and non-canonical mechanisms of dosage compensation in Drosophila.
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5
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Tomihara K, Katsuma S, Kiuchi T. Transcriptome analysis in the silkworm Bombyx mori overexpressing piRNA-resistant Masculinizer gene. Biochem Biophys Res Commun 2022; 616:104-109. [PMID: 35653824 DOI: 10.1016/j.bbrc.2022.05.073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Accepted: 05/21/2022] [Indexed: 11/02/2022]
Abstract
Dosage compensation is a process that produces a similar expression of sex-linked and autosomal genes. In the silkworm Bombyx mori with a WZ sex-determination system, the expression from the single Z in WZ females matches that of ZZ males due to the suppression of Z-linked genes in males. A primary maleness determinant gene, Masculinizer (Masc), is also required for dosage compensation. In females, silkworm Piwi is complexed with the W chromosome-derived female-specific Feminizer (Fem) PIWI-interacting RNA (piRNA) and cleaves Masc mRNA. When Fem piRNA-resistant Masc cDNA (Masc-R) is overexpressed in both sexes, only female larvae are dead during the larval stage. In this study, transcriptome analysis was performed in neonate larvae to examine the effects of Masc-R overexpression on a global gene expression profile. Z-linked genes were globally repressed in Masc-R-overexpressing females due to force-driven dosage compensation. In contrast, Masc-R overexpression had little effect on the expression of Z-linked genes and the male-specific isoform of B. mori insulin-like growth factor II mRNA-binding protein in males, indicating that excessive Masc expression strengthens neither dosage compensation nor maleness in males. Fourteen genes were differentially expressed between Masc-R-overexpressing and control neonate larvae in both sexes, suggesting Masc functions other than dosage compensation and masculinization.
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Affiliation(s)
- Kenta Tomihara
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, 113-8657, Japan
| | - Susumu Katsuma
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, 113-8657, Japan.
| | - Takashi Kiuchi
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, 113-8657, Japan.
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6
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Makki R, Meller VH. When Down Is Up: Heterochromatin, Nuclear Organization and X Upregulation. Cells 2021; 10:3416. [PMID: 34943924 DOI: 10.3390/cells10123416] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2021] [Revised: 11/29/2021] [Accepted: 12/01/2021] [Indexed: 12/21/2022] Open
Abstract
Organisms with highly differentiated sex chromosomes face an imbalance in X-linked gene dosage. Male Drosophila solve this problem by increasing expression from virtually every gene on their single X chromosome, a process known as dosage compensation. This involves a ribonucleoprotein complex that is recruited to active, X-linked genes to remodel chromatin and increase expression. Interestingly, the male X chromosome is also enriched for several proteins associated with heterochromatin. Furthermore, the polytenized male X is selectively disrupted by the loss of factors involved in repression, silencing, heterochromatin formation or chromatin remodeling. Mutations in many of these factors preferentially reduce male survival or enhance the lethality of mutations that prevent normal recognition of the X chromosome. The involvement of primarily repressive factors in a process that elevates expression has long been puzzling. Interestingly, recent work suggests that the siRNA pathway, often associated with heterochromatin formation and repression, also helps the dosage compensation machinery identify the X chromosome. In light of this finding, we revisit the evidence that links nuclear organization and heterochromatin to regulation of the male X chromosome.
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7
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Keller Valsecchi CI, Marois E, Basilicata MF, Georgiev P, Akhtar A. Distinct mechanisms mediate X chromosome dosage compensation in Anopheles and Drosophila. Life Sci Alliance 2021; 4:4/9/e202000996. [PMID: 34266874 PMCID: PMC8321682 DOI: 10.26508/lsa.202000996] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 06/27/2021] [Accepted: 06/28/2021] [Indexed: 12/14/2022] Open
Abstract
CRISPR knockout of msl-2 and epigenome analyses in Anopheles reveal that X chromosome dosage compensation in mosquitos and Drosophila is achieved by two different molecular mechanisms. Sex chromosomes induce potentially deleterious gene expression imbalances that are frequently corrected by dosage compensation (DC). Three distinct molecular strategies to achieve DC have been previously described in nematodes, fruit flies, and mammals. Is this a consequence of distinct genomes, functional or ecological constraints, or random initial commitment to an evolutionary trajectory? Here, we study DC in the malaria mosquito Anopheles gambiae. The Anopheles and Drosophila X chromosomes evolved independently but share a high degree of homology. We find that Anopheles achieves DC by a mechanism distinct from the Drosophila MSL complex–histone H4 lysine 16 acetylation pathway. CRISPR knockout of Anopheles msl-2 leads to embryonic lethality in both sexes. Transcriptome analyses indicate that this phenotype is not a consequence of defective X chromosome DC. By immunofluorescence and ChIP, H4K16ac does not preferentially enrich on the male X. Instead, the mosquito MSL pathway regulates conserved developmental genes. We conclude that a novel mechanism confers X chromosome up-regulation in Anopheles. Our findings highlight the pluralism of gene-dosage buffering mechanisms even under similar genomic and functional constraints.
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Affiliation(s)
| | - Eric Marois
- Université de Strasbourg, Centre National de la Recherche Scientifique (CNRS) UPR9022, Inserm U1257, Strasbourg, France
| | - M Felicia Basilicata
- Max Planck Institute of Immunobiology and Epigenetics, Freiburg, Germany.,Institute of Molecular Biology (IMB), Mainz, Germany
| | - Plamen Georgiev
- Max Planck Institute of Immunobiology and Epigenetics, Freiburg, Germany
| | - Asifa Akhtar
- Max Planck Institute of Immunobiology and Epigenetics, Freiburg, Germany
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8
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Villa R, Jagtap PKA, Thomae AW, Campos Sparr A, Forné I, Hennig J, Straub T, Becker PB. Divergent evolution toward sex chromosome-specific gene regulation in Drosophila. Genes Dev 2021; 35:1055-1070. [PMID: 34140353 PMCID: PMC8247607 DOI: 10.1101/gad.348411.121] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Accepted: 05/04/2021] [Indexed: 02/07/2023]
Abstract
The dosage compensation complex (DCC) of Drosophila identifies its X-chromosomal binding sites with exquisite selectivity. The principles that assure this vital targeting are known from the D. melanogaster model: DCC-intrinsic specificity of DNA binding, cooperativity with the CLAMP protein, and noncoding roX2 RNA transcribed from the X chromosome. We found that in D. virilis, a species separated from melanogaster by 40 million years of evolution, all principles are active but contribute differently to X specificity. In melanogaster, the DCC subunit MSL2 evolved intrinsic DNA-binding selectivity for rare PionX sites, which mark the X chromosome. In virilis, PionX motifs are abundant and not X-enriched. Accordingly, MSL2 lacks specific recognition. Here, roX2 RNA plays a more instructive role, counteracting a nonproductive interaction of CLAMP and modulating DCC binding selectivity. Remarkably, roX2 triggers a stable chromatin binding mode characteristic of DCC. Evidently, X-specific regulation is achieved by divergent evolution of protein, DNA, and RNA components.
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Affiliation(s)
- Raffaella Villa
- Molecular Biology Division, Biomedical Center, Ludwig-Maximilians-University Munich, 82152 Planegg-Martinsried, Germany
| | - Pravin Kumar Ankush Jagtap
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), 69117 Heidelberg, Germany
| | - Andreas W Thomae
- Molecular Biology Division, Biomedical Center, Ludwig-Maximilians-University Munich, 82152 Planegg-Martinsried, Germany.,Core Facility Bioimaging, Biomedical Center, Ludwig-Maximilians-University Munich, 82152 Planegg-Martinsried, Germany
| | - Aline Campos Sparr
- Molecular Biology Division, Biomedical Center, Ludwig-Maximilians-University Munich, 82152 Planegg-Martinsried, Germany
| | - Ignasi Forné
- Protein Analysis Unit, Biomedical Center, Ludwig-Maximilians-University Munich, 82152 Planegg-Martinsried, Germany
| | - Janosch Hennig
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), 69117 Heidelberg, Germany
| | - Tobias Straub
- Bioinformatics Unit, Biomedical Center, Ludwig-Maximilians-University Munich, 82152 Planegg-Martinsried, Germany
| | - Peter B Becker
- Molecular Biology Division, Biomedical Center, Ludwig-Maximilians-University Munich, 82152 Planegg-Martinsried, Germany
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9
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Primus S, Pozmanter C, Baxter K, Van Doren M. Tudor-domain containing protein 5-like promotes male sexual identity in the Drosophila germline and is repressed in females by Sex lethal. PLoS Genet 2019; 15:e1007617. [PMID: 31329582 DOI: 10.1371/journal.pgen.1007617] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Accepted: 06/26/2019] [Indexed: 11/19/2022] Open
Abstract
For sexually reproducing organisms, production of male or female gametes depends on specifying the correct sexual identity in the germline. In D. melanogaster, Sex lethal (Sxl) is the key gene that controls sex determination in both the soma and the germline, but how it does so in the germline is unknown, other than that it is different than in the soma. We conducted an RNA expression profiling experiment to identify direct and indirect germline targets of Sxl specifically in the undifferentiated germline. We find that, in these cells, Sxl loss does not lead to a global masculinization observed at the whole-genome level. In contrast, Sxl appears to affect a discrete set of genes required in the male germline, such as Phf7. We also identify Tudor domain containing protein 5-like (Tdrd5l) as a target for Sxl regulation that is important for male germline identity. Tdrd5l is repressed by Sxl in female germ cells, but is highly expressed in male germ cells where it promotes proper male fertility and germline differentiation. Additionally, Tdrd5l localizes to cytoplasmic granules with some characteristics of RNA Processing (P-) Bodies, suggesting that it promotes male identity in the germline by regulating post-transcriptional gene expression.
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10
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Primus S, Pozmanter C, Baxter K, Van Doren M. Tudor-domain containing protein 5-like promotes male sexual identity in the Drosophila germline and is repressed in females by Sex lethal. PLoS Genet 2019. [PMID: 31329582 DOI: 10.1101/388850] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/28/2023] Open
Abstract
For sexually reproducing organisms, production of male or female gametes depends on specifying the correct sexual identity in the germline. In D. melanogaster, Sex lethal (Sxl) is the key gene that controls sex determination in both the soma and the germline, but how it does so in the germline is unknown, other than that it is different than in the soma. We conducted an RNA expression profiling experiment to identify direct and indirect germline targets of Sxl specifically in the undifferentiated germline. We find that, in these cells, Sxl loss does not lead to a global masculinization observed at the whole-genome level. In contrast, Sxl appears to affect a discrete set of genes required in the male germline, such as Phf7. We also identify Tudor domain containing protein 5-like (Tdrd5l) as a target for Sxl regulation that is important for male germline identity. Tdrd5l is repressed by Sxl in female germ cells, but is highly expressed in male germ cells where it promotes proper male fertility and germline differentiation. Additionally, Tdrd5l localizes to cytoplasmic granules with some characteristics of RNA Processing (P-) Bodies, suggesting that it promotes male identity in the germline by regulating post-transcriptional gene expression.
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Affiliation(s)
- Shekerah Primus
- Department of Biology, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Caitlin Pozmanter
- Department of Biology, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Kelly Baxter
- Department of Biology, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Mark Van Doren
- Department of Biology, Johns Hopkins University, Baltimore, Maryland, United States of America
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11
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Andrew DJ, Chen EH, Manoli DS, Ryner LC, Arbeitman MN. Sex and the Single Fly: A Perspective on the Career of Bruce S. Baker. Genetics 2019; 212:365-376. [PMID: 31167898 PMCID: PMC6553822 DOI: 10.1534/genetics.119.301928] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Accepted: 04/01/2019] [Indexed: 11/18/2022] Open
Abstract
Bruce Baker, a preeminent Drosophila geneticist who made fundamental contributions to our understanding of the molecular genetic basis of sex differences, passed away July 1, 2018 at the age of 72. Members of Bruce's laboratory remember him as an intensely dedicated, rigorous, creative, deep-thinking, and fearless scientist. His trainees also remember his strong commitment to teaching students at every level. Bruce's career studying sex differences had three major epochs, where the laboratory was focused on: (1) sex determination and dosage compensation, (2) the development of sex-specific structures, and (3) the molecular genetic basis for sex differences in behavior. Several members of the Baker laboratory have come together to honor Bruce by highlighting some of the laboratory's major scientific contributions in these areas.
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Affiliation(s)
- Deborah J Andrew
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Elizabeth H Chen
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390
- Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Devanand S Manoli
- Department of Psychiatry, University of California, San Francisco, California 94158
- Weill Institute for Neuroscience, Center for Integrative Neuroscience, University of California, San Francisco, California 94158
| | - Lisa C Ryner
- Development Sciences Division, Roche Genentech, South San Francisco, California 94080
| | - Michelle N Arbeitman
- Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, Florida 32306
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12
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Qi Y, Wu Y, Saunders R, Chen XG, Mao C, Biedler JK, Tu ZJ. Guy1, a Y-linked embryonic signal, regulates dosage compensation in Anopheles stephensi by increasing X gene expression. eLife 2019; 8:43570. [PMID: 30888319 PMCID: PMC6440743 DOI: 10.7554/elife.43570] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Accepted: 03/16/2019] [Indexed: 12/22/2022] Open
Abstract
We previously showed that Guy1, a primary signal expressed from the Y chromosome, is a strong candidate for a male-determining factor that confers female-specific lethality in Anopheles stephensi (Criscione et al., 2016). Here, we present evidence that Guy1 increases X gene expression in Guy1-transgenic females from two independent lines, providing a mechanism underlying the Guy1-conferred female lethality. The median level gene expression (MGE) of X-linked genes is significantly higher than autosomal genes in Guy1-transgenic females while there is no significant difference in MGE between X and autosomal genes in wild-type females. Furthermore, Guy1 significantly upregulates at least 40% of the 996 genes across the X chromosome in transgenic females. Guy1-conferred female-specific lethality is remarkably stable and completely penetrant. These findings indicate that Guy1 regulates dosage compensation in An. stephensi and components of dosage compensation may be explored to develop novel strategies to control mosquito-borne diseases.
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Affiliation(s)
- Yumin Qi
- Department of Biochemistry, Virginia Tech, Blacksburg, Virginia, United States.,Fralin Life Science Institute, Virginia Tech, Blacksburg, Virginia, United States
| | - Yang Wu
- Department of Pathogen Biology, School of Public Health, Southern Medical University, Guangdong, China
| | - Randy Saunders
- Department of Biochemistry, Virginia Tech, Blacksburg, Virginia, United States.,Fralin Life Science Institute, Virginia Tech, Blacksburg, Virginia, United States
| | - Xiao-Guang Chen
- Fralin Life Science Institute, Virginia Tech, Blacksburg, Virginia, United States
| | - Chunhong Mao
- Biocomplexity Institute of Virginia Tech, Virginia Tech, Blacksburg, Virginia, United States
| | - James Kite Biedler
- Department of Biochemistry, Virginia Tech, Blacksburg, Virginia, United States.,Fralin Life Science Institute, Virginia Tech, Blacksburg, Virginia, United States
| | - Zhijian Jake Tu
- Department of Biochemistry, Virginia Tech, Blacksburg, Virginia, United States.,Fralin Life Science Institute, Virginia Tech, Blacksburg, Virginia, United States
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13
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Abstract
Sexual size dimorphism (SSD), a sex difference in body size, is widespread throughout the animal kingdom, raising the question of how sex influences existing growth regulatory pathways to bring about SSD. In insects, somatic sexual differentiation has long been considered to be controlled strictly cell-autonomously. Here, we discuss our surprising finding that in Drosophila larvae, the sex determination gene Sex-lethal (Sxl) functions in neurons to non-autonomously specify SSD. We found that Sxl is required in specific neuronal subsets to upregulate female body growth, including in the neurosecretory insulin producing cells, even though insulin-like peptides themselves appear not to be involved. SSD regulation by neuronal Sxl is also independent of its known splicing targets, transformer and msl-2, suggesting that it involves a new molecular mechanism. Interestingly, SSD control by neuronal Sxl is selective for larval, not imaginal tissue types, and operates in addition to cell-autonomous effects of Sxl and Tra, which are present in both larval and imaginal tissues. Overall, our findings add to a small but growing number of studies reporting non-autonomous, likely hormonal, control of sex differences in Drosophila, and suggest that the principles of sexual differentiation in insects and mammals may be more similar than previously thought.
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Affiliation(s)
- Annick Sawala
- a Physiology & Metabolism Laboratory , The Francis Crick Institute , London , UK
| | - Alex P Gould
- a Physiology & Metabolism Laboratory , The Francis Crick Institute , London , UK
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14
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Abstract
X chromosome regulation represents a prime example of an epigenetic phenomenon where coordinated regulation of a whole chromosome is required. In flies, this is achieved by transcriptional upregulation of X chromosomal genes in males to equalize the gene dosage differences in females. Chromatin-bound proteins and long noncoding RNAs (lncRNAs) constituting a ribonucleoprotein complex known as the male-specific lethal (MSL) complex or the dosage compensation complex mediate this process. MSL complex members decorate the male X chromosome, and their absence leads to male lethality. The male X chromosome is also enriched with histone H4 lysine 16 acetylation (H4K16ac), indicating that the chromatin compaction status of the X chromosome also plays an important role in transcriptional activation. How the X chromosome is specifically targeted and how dosage compensation is mechanistically achieved are central questions for the field. Here, we review recent advances, which reveal a complex interplay among lncRNAs, the chromatin landscape, transcription, and chromosome conformation that fine-tune X chromosome gene expression.
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Affiliation(s)
- Maria Samata
- Department of Chromatin Regulation, Max Planck Institute of Immunobiology and Epigenetics, 79108 Freiburg im Breisgau, Germany; .,Faculty of Biology, University of Freiburg, 79104 Freiburg im Breisgau, Germany
| | - Asifa Akhtar
- Department of Chromatin Regulation, Max Planck Institute of Immunobiology and Epigenetics, 79108 Freiburg im Breisgau, Germany;
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15
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Cheetham SW, Brand AH. RNA-DamID reveals cell-type-specific binding of roX RNAs at chromatin-entry sites. Nat Struct Mol Biol 2017; 25:109-114. [PMID: 29323275 PMCID: PMC5813796 DOI: 10.1038/s41594-017-0006-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Accepted: 11/09/2017] [Indexed: 02/08/2023]
Abstract
Thousands of long noncoding RNAs (lncRNAs) have been identified in eukaryotic genomes, many of which are expressed in spatially and temporally restricted patterns. Nonetheless, the roles of the majority of these transcripts are still unknown. One of the mechanisms by which lncRNAs function is through the modulation of chromatin state. To assess the functions of lncRNAs we developed RNA-DamID, a novel approach that detects lncRNA-genome interactions in a cell-type specific manner in vivo with high sensitivity and accuracy. Identifying the cell-type-specific genome occupancy of lncRNAs is key to understanding their mechanisms of action in development and disease. We used RNA-DamID to investigate targeting of the lncRNAs in the Drosophila dosage compensation complex (DCC) and show that initial targeting is cell-type-specific.
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Affiliation(s)
- Seth W Cheetham
- The Gurdon Institute and Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, UK.,Mater Research Institute, University of Queensland, Wooloongabba, Queensland, Australia
| | - Andrea H Brand
- The Gurdon Institute and Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, UK.
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16
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Rogell B, Fischer B, Rettel M, Krijgsveld J, Castello A, Hentze MW. Specific RNP capture with antisense LNA/DNA mixmers. RNA 2017; 23:1290-1302. [PMID: 28476952 PMCID: PMC5513073 DOI: 10.1261/rna.060798.117] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Accepted: 04/25/2017] [Indexed: 05/07/2023]
Abstract
RNA-binding proteins (RBPs) play essential roles in RNA biology, responding to cellular and environmental stimuli to regulate gene expression. Important advances have helped to determine the (near) complete repertoires of cellular RBPs. However, identification of RBPs associated with specific transcripts remains a challenge. Here, we describe "specific ribonucleoprotein (RNP) capture," a versatile method for the determination of the proteins bound to specific transcripts in vitro and in cellular systems. Specific RNP capture uses UV irradiation to covalently stabilize protein-RNA interactions taking place at "zero distance." Proteins bound to the target RNA are captured by hybridization with antisense locked nucleic acid (LNA)/DNA oligonucleotides covalently coupled to a magnetic resin. After stringent washing, interacting proteins are identified by quantitative mass spectrometry. Applied to in vitro extracts, specific RNP capture identifies the RBPs bound to a reporter mRNA containing the Sex-lethal (Sxl) binding motifs, revealing that the Sxl homolog sister of Sex lethal (Ssx) displays similar binding preferences. This method also revealed the repertoire of RBPs binding to 18S or 28S rRNAs in HeLa cells, including previously unknown rRNA-binding proteins.
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Affiliation(s)
- Birgit Rogell
- European Molecular Biology Laboratory (EMBL), 69117 Heidelberg, Germany
| | - Bernd Fischer
- European Molecular Biology Laboratory (EMBL), 69117 Heidelberg, Germany
- German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany
| | - Mandy Rettel
- European Molecular Biology Laboratory (EMBL), 69117 Heidelberg, Germany
| | - Jeroen Krijgsveld
- European Molecular Biology Laboratory (EMBL), 69117 Heidelberg, Germany
- German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany
| | - Alfredo Castello
- European Molecular Biology Laboratory (EMBL), 69117 Heidelberg, Germany
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, United Kingdom
| | - Matthias W Hentze
- European Molecular Biology Laboratory (EMBL), 69117 Heidelberg, Germany
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17
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Kuroda MI, Hilfiker A, Lucchesi JC. Dosage Compensation in Drosophila-a Model for the Coordinate Regulation of Transcription. Genetics 2016; 204:435-50. [PMID: 27729494 DOI: 10.1534/genetics.115.185108] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Accepted: 07/25/2016] [Indexed: 12/20/2022] Open
Abstract
The sex chromosomes have special significance in the history of genetics. The chromosomal basis of inheritance was firmly established when Calvin Bridges demonstrated that exceptions to Mendel's laws of segregation were accompanied at the cytological level by exceptional sex chromosome segregation. The morphological differences between X and Y exploited in Bridges' experiments arose as a consequence of the evolution of the sex chromosomes. Originally a homologous chromosome pair, the degeneration of the Y chromosome has been accompanied by a requirement for increased expression of the single X chromosome in males. Drosophila has been a model for the study of this dosage compensation and has brought key strengths, including classical genetics, the exceptional cytology of polytene chromosomes, and more recently, comprehensive genomics. The impact of these studies goes beyond sex chromosome regulation, providing valuable insights into mechanisms for the establishment and maintenance of chromatin domains, and for the coordinate regulation of transcription.
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18
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Abstract
Nucleus is the residence and place of work for a plethora of long noncoding RNAs. Here, we provide a summary of the functions and functional mechanisms of several relatively well studied examples of nuclear long noncoding RNAs (lncRNAs) in the nucleus, such as Xist, NEAT1, MALAT1 and TERRA. The recently identified novel EIciRNA is also highlighted. These nuclear lncRNAs play a variety of roles with diverse molecular mechanisms in animal cells. We also discuss insights and concerns about current and future studies of nuclear lnc RNAs.
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Affiliation(s)
- Bin Yu
- a The CAS Key Laboratory of Innate Immunity and Chronic Disease , CAS Center for Excellence in Molecular Cell Science , School of Life Sciences , University of Science and Technology of China , Hefei , Anhui Province , China
| | - Ge Shan
- a The CAS Key Laboratory of Innate Immunity and Chronic Disease , CAS Center for Excellence in Molecular Cell Science , School of Life Sciences , University of Science and Technology of China , Hefei , Anhui Province , China
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19
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Moschall R, Gaik M, Medenbach J. Promiscuity in post-transcriptional control of gene expression: Drosophila sex-lethal and its regulatory partnerships. FEBS Lett 2017; 591:1471-1488. [PMID: 28391641 PMCID: PMC5488161 DOI: 10.1002/1873-3468.12652] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Revised: 03/08/2017] [Accepted: 04/04/2017] [Indexed: 12/28/2022]
Abstract
The Drosophila RNA‐binding protein Sex‐lethal (Sxl) is a potent post‐transcriptional regulator of gene expression that controls female development. It regulates the expression of key factors involved in sex‐specific differences in morphology, behavior, and dosage compensation. Functional Sxl protein is only expressed in female flies, where it binds to U‐rich RNA motifs present in its target mRNAs to regulate their fate. Sxl is a very versatile regulator that, by shuttling between the nucleus and the cytoplasm, can regulate almost all aspects of post‐transcriptional gene expression including RNA processing, nuclear export, and translation. For these functions, Sxl employs multiple interactions to either antagonize RNA‐processing factors or to recruit various coregulators, thus allowing it to establish a female‐specific gene expression pattern. Here, we summarize the current knowledge about Sxl function and review recent mechanistic and structural studies that further our understanding of how such a seemingly ‘simple’ RNA‐binding protein can exert this plethora of different functions.
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Affiliation(s)
| | - Monika Gaik
- Max Planck Research Group at the Malopolska Centre of Biotechnology, Jagiellonian University, Krakow, Poland
| | - Jan Medenbach
- Institute of Biochemistry I, University of Regensburg, Germany
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20
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Cheng B, Kuppanda N, Aldrich JC, Akbari OS, Ferree PM. Male-Killing Spiroplasma Alters Behavior of the Dosage Compensation Complex during Drosophila melanogaster Embryogenesis. Curr Biol 2016; 26:1339-45. [PMID: 27161498 DOI: 10.1016/j.cub.2016.03.050] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Revised: 03/16/2016] [Accepted: 03/21/2016] [Indexed: 01/11/2023]
Abstract
Numerous arthropods harbor maternally transmitted bacteria that induce the preferential death of males [1-7]. This sex-specific lethality benefits the bacteria because males are "dead ends" regarding bacterial transmission, and their absence may result in additional resources for their viable female siblings who can thereby more successfully transmit the bacteria [5]. Although these symbionts disrupt a range of developmental processes [8-10], the underlying cellular mechanisms are largely unknown. It was previously shown that mutations in genes of the dosage compensation pathway of Drosophila melanogaster suppressed male killing caused by the bacterium, Spiroplasma [10]. This result suggested that dosage compensation is a target of Spiroplasma. However, it remains unclear how this pathway is affected, and whether the underlying interactions require the male-specific cellular environment. Here, we investigated the cellular basis of male embryonic lethality in D. melanogaster induced by Spiroplasma. We found that the dosage compensation complex (DCC), which acetylates X chromatin in males [11], becomes mis-localized to ectopic regions of the nucleus immediately prior to the killing phase. This effect was accompanied by inappropriate histone acetylation and genome-wide mis-regulation of gene expression. Artificially induced formation of the DCC in infected females, through transgenic expression of the DCC-specific gene msl-2, resulted in mis-localization of this complex to non-X regions and early Spiroplasma-induced death, mirroring the killing effects in males. These findings strongly suggest that Spiroplasma initiates male killing by targeting the dosage compensation machinery directly and independently of other cellular features characteristic of the male sex.
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Affiliation(s)
- Becky Cheng
- W.M. Keck Science Department, Claremont McKenna, Pitzer and Scripps Colleges, 925 N. Mills Avenue, Claremont, CA 91711, USA
| | - Nitin Kuppanda
- W.M. Keck Science Department, Claremont McKenna, Pitzer and Scripps Colleges, 925 N. Mills Avenue, Claremont, CA 91711, USA
| | - John C Aldrich
- W.M. Keck Science Department, Claremont McKenna, Pitzer and Scripps Colleges, 925 N. Mills Avenue, Claremont, CA 91711, USA
| | - Omar S Akbari
- Department of Entomology and Riverside Center for Disease Vector Research, Institute for Integrative Genome Biology, University of California, Riverside, Riverside, CA 92521, USA.
| | - Patrick M Ferree
- W.M. Keck Science Department, Claremont McKenna, Pitzer and Scripps Colleges, 925 N. Mills Avenue, Claremont, CA 91711, USA.
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21
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Erickson JW. Primary Sex Determination in Drosophila melanogaster Does Not Rely on the Male-Specific Lethal Complex. Genetics 2016; 202:541-9. [PMID: 26614741 DOI: 10.1534/genetics.115.182931] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Accepted: 11/21/2015] [Indexed: 11/18/2022] Open
Abstract
It has been proposed that the Male Specific Lethal (MSL) complex is active in Drosophila melanogaster embryos of both sexes prior to the maternal-to-zygotic transition. Elevated gene expression from the two X chromosomes of female embryos is proposed to facilitate the stable establishment of Sex-lethal (Sxl) expression, which determines sex and represses further activity of the MSL complex, leaving it active only in males. Important supporting data included female-lethal genetic interactions between the seven msl genes and either Sxl or scute and sisterlessA, two of the X-signal elements (XSE) that regulate early Sxl expression. Here I report contrary findings that there are no female-lethal genetic interactions between the msl genes and Sxl or its XSE regulators. Fly stocks containing the msl3(1) allele were found to exhibit a maternal-effect interaction with Sxl, scute, and sisterlessA mutations, but genetic complementation experiments showed that msl3 is neither necessary nor sufficient for the female-lethal interactions, which appear to be due to an unidentified maternal regulator of Sxl. Published data cited as evidence for an early function of the MSL complex in females, including a maternal effect of msl2, have been reevaluated and found not to support a maternal, or other effect, of the MSL complex in sex determination. These findings suggest that the MSL complex is not involved in primary sex determination or in X chromosome dosage compensation prior to the maternal-to-zygotic transition.
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22
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Affiliation(s)
- Justin J.-L. Wong
- Gene and Stem Cell Therapy Program, Centenary Institute; Royal Prince Alfred Hospital; Camperdown Australia
- Sydney Medical School; University of Sydney; Camperdown Australia
| | - Amy Y. M. Au
- Gene and Stem Cell Therapy Program, Centenary Institute; Royal Prince Alfred Hospital; Camperdown Australia
- Sydney Medical School; University of Sydney; Camperdown Australia
| | - William Ritchie
- Gene and Stem Cell Therapy Program, Centenary Institute; Royal Prince Alfred Hospital; Camperdown Australia
- Sydney Medical School; University of Sydney; Camperdown Australia
- Department of Bioinformatics, Centenary Institute; Royal Prince Alfred Hospital; Camperdown Australia
| | - John E. J. Rasko
- Gene and Stem Cell Therapy Program, Centenary Institute; Royal Prince Alfred Hospital; Camperdown Australia
- Sydney Medical School; University of Sydney; Camperdown Australia
- Cell and Molecular Therapies; Royal Prince Alfred Hospital; Camperdown Australia
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23
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Sun X, Yang H, Sturgill D, Oliver B, Rabinow L, Samson ML. Sxl-Dependent, tra/tra2-Independent Alternative Splicing of the Drosophila melanogaster X-Linked Gene found in neurons. G3 (Bethesda) 2015; 5:2865-74. [PMID: 26511498 DOI: 10.1534/g3.115.023721] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Somatic sexual determination and behavior in Drosophila melanogaster are under the control of a genetic cascade initiated by Sex lethal (Sxl). In the female soma, SXL RNA-binding protein regulates the splicing of transformer (tra) transcripts into a female-specific form. The RNA-binding protein TRA and its cofactor TRA2 function in concert in females, whereas SXL, TRA, and TRA2 are thought to not function in males. To better understand sex-specific regulation of gene expression, we analyzed male and female head transcriptome datasets for expression levels and splicing, quantifying sex-biased gene expression via RNA-Seq and qPCR. Our data uncouple the effects of Sxl and tra/tra2 in females in the-sex-biased alternative splicing of head transcripts from the X-linked locus found in neurons (fne), encoding a pan-neuronal RNA-binding protein of the ELAV family. We show that FNE protein levels are downregulated by Sxl in female heads, also independently of tra/tra2. We argue that this regulation may have important sexually dimorphic consequences for the regulation of nervous system development or function.
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24
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Linger RJ, Belikoff EJ, Scott MJ. Dosage Compensation of X-Linked Muller Element F Genes but Not X-Linked Transgenes in the Australian Sheep Blowfly. PLoS One 2015; 10:e0141544. [PMID: 26506426 PMCID: PMC4624761 DOI: 10.1371/journal.pone.0141544] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Accepted: 10/10/2015] [Indexed: 11/25/2022] Open
Abstract
In most animals that have X and Y sex chromosomes, chromosome-wide mechanisms are used to balance X-linked gene expression in males and females. In the fly Drosophila melanogaster, the dosage compensation mechanism also generally extends to X-linked transgenes. Over 70 transgenic lines of the Australian sheep blowfly Lucilia cuprina have been made as part of an effort to develop male-only strains for a genetic control program of this major pest of sheep. All lines carry a constitutively expressed fluorescent protein marker gene. In all 12 X-linked lines, female larvae show brighter fluorescence than male larvae, suggesting the marker gene is not dosage compensated. This has been confirmed by quantitative RT-PCR for selected lines. To determine if endogenous X-linked genes are dosage compensated, we isolated 8 genes that are orthologs of genes that are on the fourth chromosome in D. melanogaster. Recent evidence suggests that the D. melanogaster fourth chromosome, or Muller element F, is the ancestral X chromosome in Diptera that has reverted to an autosome in Drosophila species. We show by quantitative PCR of male and female DNA that 6 of the 8 linkage group F genes reside on the X chromosome in L. cuprina. The other two Muller element F genes were found to be autosomal in L. cuprina, whereas two Muller element B genes were found on the same region of the X chromosome as the L. cuprina orthologs of the D. melanogaster Ephrin and gawky genes. We find that the L. cuprina X chromosome genes are equally expressed in males and females (i.e., fully dosage compensated). Thus, unlike in Drosophila, it appears that the Lucilia dosage compensation system is specific for genes endogenous to the X chromosome and cannot be co-opted by recently arrived transgenes.
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Affiliation(s)
- Rebecca J. Linger
- Department of Entomology, North Carolina State University, Campus Box 7613, Raleigh, NC, 27695–7613, United States of America
| | - Esther J. Belikoff
- Department of Entomology, North Carolina State University, Campus Box 7613, Raleigh, NC, 27695–7613, United States of America
| | - Maxwell J. Scott
- Department of Entomology, North Carolina State University, Campus Box 7613, Raleigh, NC, 27695–7613, United States of America
- * E-mail:
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25
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Abstract
Coherent splicing networks arise from many discrete splicing decisions regulated in unison. Here, we examine the properties of robust, context-specific splicing networks. We propose that a subset of key splicing regulators, or "master splicing factors," respond to environmental cues to establish and maintain tissue transcriptomes during development.
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Affiliation(s)
- Mohini Jangi
- David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Phillip A Sharp
- David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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26
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Abstract
DNA replication is a dynamic process that occurs in a temporal order along each of the chromosomes. A consequence of the temporally coordinated activation of replication origins is the establishment of broad domains (>100 kb) that replicate either early or late in S phase. This partitioning of the genome into early and late replication domains is important for maintaining genome stability, gene dosage, and epigenetic inheritance; however, the molecular mechanisms that define and establish these domains are poorly understood. The modENCODE Project provided an opportunity to investigate the chromatin features that define the Drosophila replication timing program in multiple cell lines. The majority of early and late replicating domains in the Drosophila genome were static across all cell lines; however, a small subset of domains was dynamic and exhibited differences in replication timing between the cell lines. Both origin selection and activation contribute to defining the DNA replication program. Our results suggest that static early and late replicating domains were defined at the level of origin selection (ORC binding) and likely mediated by chromatin accessibility. In contrast, dynamic domains exhibited low ORC densities in both cell types, suggesting that origin activation and not origin selection governs the plasticity of the DNA replication program. Finally, we show that the male-specific early replication of the X chromosome is dependent on the dosage compensation complex (DCC), suggesting that the transcription and replication programs respond to the same chromatin cues. Specifically, MOF-mediated hyperacetylation of H4K16 on the X chromosome promotes both the up-regulation of male-specific transcription and origin activation.
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Affiliation(s)
- Yoav Lubelsky
- Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710, USA
| | - Joseph A Prinz
- Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710, USA
| | - Leyna DeNapoli
- Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710, USA
| | - Yulong Li
- Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710, USA
| | - Jason A Belsky
- Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710, USA
| | - David M MacAlpine
- Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710, USA
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27
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Figueiredo MLA, Kim M, Philip P, Allgardsson A, Stenberg P, Larsson J. Non-coding roX RNAs prevent the binding of the MSL-complex to heterochromatic regions. PLoS Genet 2014; 10:e1004865. [PMID: 25501352 PMCID: PMC4263465 DOI: 10.1371/journal.pgen.1004865] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2014] [Accepted: 10/30/2014] [Indexed: 12/29/2022] Open
Abstract
Long non-coding RNAs contribute to dosage compensation in both mammals and Drosophila by inducing changes in the chromatin structure of the X-chromosome. In Drosophila melanogaster, roX1 and roX2 are long non-coding RNAs that together with proteins form the male-specific lethal (MSL) complex, which coats the entire male X-chromosome and mediates dosage compensation by increasing its transcriptional output. Studies on polytene chromosomes have demonstrated that when both roX1 and roX2 are absent, the MSL-complex becomes less abundant on the male X-chromosome and is relocated to the chromocenter and the 4th chromosome. Here we address the role of roX RNAs in MSL-complex targeting and the evolution of dosage compensation in Drosophila. We performed ChIP-seq experiments which showed that MSL-complex recruitment to high affinity sites (HAS) on the X-chromosome is independent of roX and that the HAS sequence motif is conserved in D. simulans. Additionally, a complete and enzymatically active MSL-complex is recruited to six specific genes on the 4th chromosome. Interestingly, our sequence analysis showed that in the absence of roX RNAs, the MSL-complex has an affinity for regions enriched in Hoppel transposable elements and repeats in general. We hypothesize that roX mutants reveal the ancient targeting of the MSL-complex and propose that the role of roX RNAs is to prevent the binding of the MSL-complex to heterochromatin. In both fruit flies and humans, males and females have different sets of sex chromosomes. This generates differences in gene dosage that must be compensated for by adjusting the transcriptional output of most genes located on the X-chromosome. The specific recognition and targeting of the X-chromosome is essential for such dosage compensation. In fruit flies, dosage compensation is mediated by the male-specific lethal (MSL) complex, which upregulates gene transcription on the male X-chromosome. The MSL-complex consists of five proteins and two non-coding RNAs, roX1 and roX2. While non-coding RNAs are known to be critical for dosage compensation in both flies and mammals, their precise functions remain elusive. Here we present a study on the targeting and function of the MSL-complex in the absence of roX RNAs. The results obtained suggest that the dosage compensating MSL-complex has an intrinsic tendency to target repeat-rich regions and that the function of roX RNAs is to prevent its binding to such targets. Our findings reveal an ancient targeting and regulatory function of the MSL-complex that has been adapted for use in dosage compensation and modified by the rapidly evolving noncoding roX RNAs.
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Affiliation(s)
| | - Maria Kim
- Department of Molecular Biology, Umeå University, Umeå, Sweden
| | - Philge Philip
- Department of Molecular Biology, Umeå University, Umeå, Sweden
- Computational Life Science Cluster (CLiC), Umeå University, Umeå, Sweden
| | | | - Per Stenberg
- Department of Molecular Biology, Umeå University, Umeå, Sweden
- Computational Life Science Cluster (CLiC), Umeå University, Umeå, Sweden
| | - Jan Larsson
- Department of Molecular Biology, Umeå University, Umeå, Sweden
- * E-mail:
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28
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Abstract
Post-transcriptional pre-mRNA splicing has emerged as a critical step in the gene expression cascade greatly influencing diversification and spatiotemporal control of the proteome in many developmental processes. The percentage of genes targeted by alternative splicing (AS) is shown to be over 95% in humans and 60% in Drosophila. Therefore, it is evident that deregulation of this process underlies many genetic diseases. Among all tissues, the brain shows the highest transcriptome diversity, which is not surprising in view of the complex inter- and intracellular networks underlying the development of this organ. Reports of isoforms known to function at different steps during Drosophila nervous system development are rapidly increasing as well as knowledge on their regulation and function, highlighting the role of AS during neuronal development in Drosophila.
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Affiliation(s)
- Carmen Mohr
- Institute of Human Genetics, University Medical Center Freiburg , Freiburg , Germany
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29
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Wang XY, Zheng ZZ, Song HS, Xu YZ. Conserved RNA cis-elements regulate alternative splicing of Lepidopteran doublesex. Insect Biochem Mol Biol 2014; 44:1-11. [PMID: 24239545 DOI: 10.1016/j.ibmb.2013.10.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2013] [Revised: 10/10/2013] [Accepted: 10/29/2013] [Indexed: 06/02/2023]
Abstract
Doublesex (dsx) is a downstream key regulator in insect sex determination pathway. In Drosophila, alternative splicing of Dm-dsx gene is sex-specifically regulated by transformer (tra), in which the functional TRA promotes female-specific Dm-dsx. However, the sex determination pathway in Lepidoptera is not well understood; here we focused on alternative splicing of doublesex (dsx) in two agricultural pests, Asian corn borer (Ostrinia furnacalis) and cotton bollworm (Helicoverpa armigera), as well as the silkworm (Bombyx mori). More than a dozen new alternative splicing isoforms of dsx were found in the Lepidopteran females, which exist in all tested developmental stages and differentiated tissues. Alignment of mRNA and protein sequences of doublesex revealed high conservation of this gene in Lepidoptera. Strength analysis of splice sites revealed a weak 5' splice site at intron 3 in Lepidopteran dsx, which was experimentally confirmed. Furthermore, we identified highly conserved RNA sequences in the Lepidopteran dsx, including RNA elements I (14 nt), II (11 nt), III (26 nt), IV (17 nt), 3E-1 (8 nt) and 3E-2 (8 nt). The RNA elements III and IV were previously found in exon 4 of B. mori dsx and bound with Bm-PSI, which suppressed the inclusion of exons 3 & 4 into the male-specific Bm-dsx. Then we identified and analyzed the homologous genes of Bm-psi in the two Lepidopteran pests, which expressed at similar levels and exhibited a unique isoform in the males and females from each Lepidoptera. Importantly, mutagenesis of Bm-dsx mini-genes and their expression in BmN cell line demonstrated that three RNA elements are involved in the female-specific alternative splicing of Bm-dsx. Mutations in the RNA cis-elements 3E-1 and 3E-2 resulted in decreased inclusion of exon 3 into the female-specific dsx mRNA, suggesting that these two elements would be exonic splicing enhancers that facilitate the recognition of the weak 5' splice site at intron 3 of Lepidopteran dsx. We propose that the 5' splice sites at intron 3 are weak, resulting in multiple alternative splicing events in intron 3 of female Lepidoptera dsx. Activation of the 5' splice site requires regulatory cis-elements in exons 3 for female-specific splicing of Lepidoptera dsx.
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Affiliation(s)
- Xiu-Ye Wang
- Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | - Zeng-Zhang Zheng
- Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | - Hong-Sheng Song
- College of Life Sciences, Shanghai University, Shanghai 200444, China
| | - Yong-Zhen Xu
- Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China.
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Horiuchi K, Kawamura T, Iwanari H, Ohashi R, Naito M, Kodama T, Hamakubo T. Identification of Wilms' tumor 1-associating protein complex and its role in alternative splicing and the cell cycle. J Biol Chem 2013; 288:33292-302. [PMID: 24100041 DOI: 10.1074/jbc.m113.500397] [Citation(s) in RCA: 239] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Wilms' tumor 1-associating protein (WTAP) is a putative splicing regulator that is thought to be required for cell cycle progression through the stabilization of cyclin A2 mRNA and mammalian early embryo development. To further understand how WTAP acts in the context of the cellular machinery, we identified its interacting proteins in human umbilical vein endothelial cells and HeLa cells using shotgun proteomics. Here we show that WTAP forms a novel protein complex including Hakai, Virilizer homolog, KIAA0853, RBM15, the arginine/serine-rich domain-containing proteins BCLAF1 and THRAP3, and certain general splicing regulators, most of which have reported roles in post-transcriptional regulation. The depletion of these respective components of the complex resulted in reduced cell proliferation along with G2/M accumulation. Double knockdown of the serine/arginine-rich (SR)-like proteins BCLAF1 and THRAP3 by siRNA resulted in a decrease in the nuclear speckle localization of WTAP, whereas the nuclear speckles were intact. Furthermore, we found that the WTAP complex regulates alternative splicing of the WTAP pre-mRNA by promoting the production of a truncated isoform, leading to a change in WTAP protein expression. Collectively, these findings show that the WTAP complex is a novel component of the RNA processing machinery, implying an important role in both posttranscriptional control and cell cycle regulation.
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Affiliation(s)
- Keiko Horiuchi
- From the Department of Quantitative Biology and Medicine and
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Abstract
Translational regulation plays an essential role in many phases of the Drosophila life cycle. During embryogenesis, specification of the developing body pattern requires co-ordination of the translation of oskar, gurken and nanos mRNAs with their subcellular localization. In addition, dosage compensation is controlled by Sex-lethal-mediated translational regulation while dFMR1 (the Drosophila homologue of the fragile X mental retardation protein) controls translation of various mRNAs which function in the nervous system. Here we describe some of the mechanisms that are utilized to regulate these various processes. Our review highlights the complexity that can be involved with multiple factors employing different mechanisms to control the translation of a single mRNA.
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Affiliation(s)
- James E Wilhelm
- Department of Embryology, Carnegie Institution of Washington, Baltimore, MD 21210, USA
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Maenner S, Müller M, Becker PB. Roles of long, non-coding RNA in chromosome-wide transcription regulation: lessons from two dosage compensation systems. Biochimie 2012; 94:1490-8. [PMID: 22239950 DOI: 10.1016/j.biochi.2011.12.026] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2011] [Accepted: 12/31/2011] [Indexed: 11/17/2022]
Abstract
A large part of higher eukaryotic genomes is transcribed into RNAs lacking any significant open reading frame. This "non-coding part" has been shown to actively contribute to regulating gene expression, but the mechanisms are largely unknown. Particularly instructive examples are provided by the dosage compensation systems, which assure that the single X chromosome in male cells and the two X chromosomes in female cells give rise to similar amounts of gene product. Although this is achieved by very different strategies in mammals and fruit flies, long, non-coding RNAs (lncRNAs) are involved in both cases. Here we summarize recent progress towards unraveling the mechanisms, by which the Xist and roX RNAs mediate the selective association of regulators with individual target chromosomes, to initiate dosage compensation in mammals and fruit flies, respectively.
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Affiliation(s)
- Sylvain Maenner
- Adolf-Butenandt-Institute and Center for Integrated Protein Science (CIPSM), Ludwig Maximilian University Munich, Schillerstrasse 44, 80336 München, Germany.
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Abstract
Equalizing sex chromosome expression between the sexes when they have largely differing gene content appears to be necessary, and across species, is accomplished in a variety of ways. Even in birds, where the process is less than complete, a mechanism to reduce the difference in gene dose between the sexes exists. In early development, while the dosage difference is unregulated and still in flux, it is frequently exploited by sex determination mechanisms. The Drosophila female sex determination process is one clear example, determining the sexes based on X chromosome dose. Recent data show that in Drosophila, the female sex not only reads this gene balance difference, but at the same time usurps the moment. Taking advantage of the transient default state of male dosage compensation, the sex determination master-switch Sex-lethal which resides on the X, has its expression levels enhanced before it works to correct the gene imbalance. Intriguingly, key developmental genes which could create developmental havoc if their levels were unbalanced show more exquisite regulation, suggesting nature distinguishes them and ensures their expression is kept in the desirable range.
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Affiliation(s)
- Jamila I Horabin
- Department of Biomedical Sciences, Florida State University, Tallahassee, FL, USA.
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Medenbach J, Seiler M, Hentze MW. Translational control via protein-regulated upstream open reading frames. Cell 2011; 145:902-13. [PMID: 21663794 DOI: 10.1016/j.cell.2011.05.005] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2010] [Revised: 03/21/2011] [Accepted: 05/02/2011] [Indexed: 12/22/2022]
Abstract
Analysis of the regulation of msl-2 mRNA by Sex lethal (SXL), which is critical for dosage compensation in Drosophila, has uncovered a mode of translational control based on common 5' untranslated region elements, upstream open reading frames (uORFs), and interaction sites for RNA-binding proteins. We show that SXL binding downstream of a short uORF imposes a strong negative effect on major reading frame translation. The underlying mechanism involves increasing initiation of scanning ribosomes at the uORF and augmenting its impediment to downstream translation. Our analyses reveal that SXL exerts its effect controlling initiation, not elongation or termination, at the uORF. Probing the generality of the underlying mechanism, we show that the regulatory module that we define experimentally functions in a heterologous context, and we identify natural Drosophila mRNAs that are regulated via this module. We propose that protein-regulated uORFs constitute a systematic principle for the regulation of protein synthesis.
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Laverty C, Li F, Belikoff EJ, Scott MJ. Abnormal dosage compensation of reporter genes driven by the Drosophila glass multiple reporter (GMR) enhancer-promoter. PLoS One 2011; 6:e20455. [PMID: 21655213 PMCID: PMC3105068 DOI: 10.1371/journal.pone.0020455] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2011] [Accepted: 04/26/2011] [Indexed: 11/19/2022] Open
Abstract
In Drosophila melanogaster the male specific lethal (MSL) complex is required for upregulation of expression of most X-linked genes in males, thereby achieving X chromosome dosage compensation. The MSL complex is highly enriched across most active X-linked genes with a bias towards the 3′ end. Previous studies have shown that gene transcription facilitates MSL complex binding but the type of promoter did not appear to be important. We have made the surprising observation that genes driven by the glass multiple reporter (GMR) enhancer-promoter are not dosage compensated at X-linked sites. The GMR promoter is active in all cells in, and posterior to, the morphogenetic furrow of the developing eye disc. Using phiC31 integrase-mediated targeted integration, we measured expression of lacZ reporter genes driven by either the GMR or armadillo (arm) promoters at each of three X-linked sites. At all sites, the arm-lacZ reporter gene was dosage compensated but GMR-lacZ was not. We have investigated why GMR-driven genes are not dosage compensated. Earlier or constitutive expression of GMR-lacZ did not affect the level of compensation. Neither did proximity to a strong MSL binding site. However, replacement of the hsp70 minimal promoter with a minimal promoter from the X-linked 6-Phosphogluconate dehydrogenase gene did restore partial dosage compensation. Similarly, insertion of binding sites for the GAGA and DREF factors upstream of the GMR promoter led to significantly higher lacZ expression in males than females. GAGA and DREF have been implicated to play a role in dosage compensation. We conclude that the gene promoter can affect MSL complex-mediated upregulation and dosage compensation. Further, it appears that the nature of the basal promoter and the presence of binding sites for specific factors influence the ability of a gene promoter to respond to the MSL complex.
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Affiliation(s)
- Corey Laverty
- Institute of Molecular BioSciences, Massey University, Palmerston North, New Zealand
| | - Fang Li
- Institute of Molecular BioSciences, Massey University, Palmerston North, New Zealand
| | - Esther J. Belikoff
- Institute of Molecular BioSciences, Massey University, Palmerston North, New Zealand
| | - Maxwell J. Scott
- Institute of Molecular BioSciences, Massey University, Palmerston North, New Zealand
- * E-mail:
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Abstract
Dosage compensation of X-linked genes is a phenomenon of concerted, chromosome-wide regulation of gene expression underpinned by sustained and tightly regulated histone modifications and chromatin remodeling, coupled with constrains of nuclear architecture. This elaborate process allows the accomplishment of regulated expression of genes on the single male X chromosome to levels comparable to those expressed from the two X chromosomes in females. The ribonucleoprotein Male Specific Lethal (MSL) complex is enriched on the male X chromosome and is intricately involved in this process in Drosophila melanogaster. In this review we discuss the recent advances that highlight the complexity lying behind regulation of gene expression by just two-fold.
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Affiliation(s)
- Plamen Georgiev
- Max Planck Institute of Immunobiology and Epigenetics, Freiburg, Germany
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Hartmann B, Castelo R, Miñana B, Peden E, Blanchette M, Rio DC, Singh R, Valcárcel J. Distinct regulatory programs establish widespread sex-specific alternative splicing in Drosophila melanogaster. RNA 2011; 17:453-468. [PMID: 21233220 PMCID: PMC3039145 DOI: 10.1261/rna.2460411] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2010] [Accepted: 11/22/2010] [Indexed: 05/30/2023]
Abstract
In Drosophila melanogaster, female-specific expression of Sex-lethal (SXL) and Transformer (TRA) proteins controls sex-specific alternative splicing and/or translation of a handful of regulatory genes responsible for sexual differentiation and behavior. Recent findings in 2009 by Telonis-Scott et al. document widespread sex-biased alternative splicing in fruitflies, including instances of tissue-restricted sex-specific splicing. Here we report results arguing that some of these novel sex-specific splicing events are regulated by mechanisms distinct from those established by female-specific expression of SXL and TRA. Bioinformatic analysis of SXL/TRA binding sites, experimental analysis of sex-specific splicing in S2 and Kc cells lines and of the effects of SXL knockdown in Kc cells indicate that SXL-dependent and SXL-independent regulatory mechanisms coexist within the same cell. Additional determinants of sex-specific splicing can be provided by sex-specific differences in the expression of RNA binding proteins, including Hrp40/Squid. We report that sex-specific alternative splicing of the gene hrp40/squid leads to sex-specific differences in the levels of this hnRNP protein. The significant overlap between sex-regulated alternative splicing changes and those induced by knockdown of hrp40/squid and the presence of related sequence motifs enriched near subsets of Hrp40/Squid-regulated and sex-regulated splice sites indicate that this protein contributes to sex-specific splicing regulation. A significant fraction of sex-specific splicing differences are absent in germline-less tudor mutant flies. Intriguingly, these include alternative splicing events that are differentially spliced in tissues distant from the germline. Collectively, our results reveal that distinct genetic programs control widespread sex-specific splicing in Drosophila melanogaster.
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Gladstein N, McKeon MN, Horabin JI. Requirement of male-specific dosage compensation in Drosophila females--implications of early X chromosome gene expression. PLoS Genet 2010; 6:e1001041. [PMID: 20686653 PMCID: PMC2912388 DOI: 10.1371/journal.pgen.1001041] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2009] [Accepted: 06/24/2010] [Indexed: 11/18/2022] Open
Abstract
Dosage compensation equates between the sexes the gene dose of sex chromosomes that carry substantially different gene content. In Drosophila, the single male X chromosome is hypertranscribed by approximately two-fold to effect this correction. The key genes are male lethal and appear not to be required in females, or affect their viability. Here, we show these male lethals do in fact have a role in females, and they participate in the very process which will eventually shut down their function—female determination. We find the male dosage compensation complex is required for upregulating transcription of the sex determination master switch, Sex-lethal, an X-linked gene which is specifically activated in females in response to their two X chromosomes. The levels of some X-linked genes are also affected, and some of these genes are used in the process of counting the number of X chromosomes early in development. Our data suggest that before the female state is set, the ground state is male and female X chromosome expression is elevated. Females thus utilize the male dosage compensation process to amplify the signal which determines their fate. When substantially different, sex chromosomes present the challenge of not only gene dose inequity between the sexes, in the heterogametic sex where one chromosome (frequently the Y) carries few genes, but also an inequity relative to the autosomes which are diploid. Dosage compensation refers to the process which equates gene dose between the sexes. Recent results, however, indicate that the mammalian X chromosome avoids monosomy and has a level of expression that is two-fold relative to the autosomes. Hyperactive X chromosome expression in Caenorhabditis elegans has also been suggested, and dosage compensation in the hermaphrodite appears to lower expression of the X chromosomes to match autosome levels. We find that, before the female state is set in Drosophila, the X chromosomes may also express their genes at the two-fold male level and that this level of expression is used to female advantage to consolidate their sex determination. Together, the results suggest that elevated X chromosome expression may be the norm, and that the various dosage compensation processes different organisms utilize reflect a mechanism to counteract an initial hyperactive X chromosome state.
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Affiliation(s)
- Natalie Gladstein
- Department of Biomedical Sciences, Florida State University, Tallahassee, Florida, United States of America
| | - Meghan N. McKeon
- Department of Biomedical Sciences, Florida State University, Tallahassee, Florida, United States of America
| | - Jamila I. Horabin
- Department of Biomedical Sciences, Florida State University, Tallahassee, Florida, United States of America
- * E-mail:
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Prabhakaran M, Kelley RL. A new strategy for isolating genes controlling dosage compensation in Drosophila using a simple epigenetic mosaic eye phenotype. BMC Biol 2010; 8:80. [PMID: 20537125 PMCID: PMC2893135 DOI: 10.1186/1741-7007-8-80] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2010] [Accepted: 06/10/2010] [Indexed: 12/18/2022] Open
Abstract
Background The Drosophila Male Specific Lethal (MSL) complex contains chromatin modifying enzymes and non-coding roX RNA. It paints the male X at hundreds of bands where it acetylates histone H4 at lysine 16. This epigenetic mark increases expression from the single male X chromosome approximately twofold above what gene-specific factors produce from each female X chromosome. This equalises X-linked gene expression between the sexes. Previous screens for components of dosage compensation relied on a distinctive male-specific lethal phenotype. Results Here, we report a new strategy relying upon an unusual male-specific mosaic eye pigmentation phenotype produced when the MSL complex acts upon autosomal roX1 transgenes. Screening the second chromosome identified at least five loci, two of which are previously described components of the MSL complex. We focused our analysis on the modifier alleles of MSL1 and MLE (for 'maleless'). The MSL1 lesions are not simple nulls, but rather alter the PEHE domain that recruits the MSL3 chromodomain and MOF ('males absent on first') histone acetyltransferase subunits to the complex. These mutants are compromised in their ability to recruit MSL3 and MOF, dosage compensate the X, and support long distance spreading from roX1 transgenes. Yet, paradoxically, they were isolated because they somehow increase MSL complex activity immediately around roX1 transgenes in combination with wild-type MSL1 subunits. Conclusions We propose that these diverse phenotypes arise from perturbations in assembly of MSL subunits onto nascent roX transcripts. This strategy is a promising alternative route for identifying previously unknown components of the dosage compensation pathway and novel alleles of known MSL proteins.
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Abstract
Drosophila maleless (MLE) is a member of helicase superfamily 2 and functions as a dosage compensation factor essential for the development of male flies. This function provides a good opportunity to investigate diverse biochemical activities associated with MLE in the context of a defined in vivo pathway, i.e., the transcriptional activation of X-linked genes. We have shown for the first time that MLE catalyzes the unwinding of both DNA and RNA and that MLE helicase activity is essential for its in vivo function. Also, we have provided evidence that MLE stimulates the transcriptional activity of roX2 on the X chromosome. We have also found that MLE interacts with dsDNA, topoisomerase II, and nucleosome. This observation supports a current model of dosage compensation: transcriptional activation of X-linked genes is causally associated with conformational change in the male X chromosome, subsequent to the targeted association of the dosage compensation complex (DCC).
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Gallach M, Arnau V, Aldecoa R, Marín I. A sequence motif enriched in regions bound by the Drosophila dosage compensation complex. BMC Genomics 2010; 11:169. [PMID: 20226017 PMCID: PMC2848247 DOI: 10.1186/1471-2164-11-169] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2009] [Accepted: 03/12/2010] [Indexed: 11/29/2022] Open
Abstract
Background In Drosophila melanogaster, dosage compensation is mediated by the action of the dosage compensation complex (DCC). How the DCC recognizes the fly X chromosome is still poorly understood. Characteristic sequence signatures at all DCC binding sites have not hitherto been found. Results In this study, we compare the known binding sites of the DCC with oligonucleotide profiles that measure the specificity of the sequences of the D. melanogaster X chromosome. We show that the X chromosome regions bound by the DCC are enriched for a particular type of short, repetitive sequences. Their distribution suggests that these sequences contribute to chromosome recognition, the generation of DCC binding sites and/or the local spreading of the complex. Comparative data indicate that the same sequences may be involved in dosage compensation in other Drosophila species. Conclusions These results offer an explanation for the wild-type binding of the DCC along the Drosophila X chromosome, contribute to delineate the forces leading to the establishment of dosage compensation and suggest new experimental approaches to understand the precise biochemical features of the dosage compensation system.
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Affiliation(s)
- Miguel Gallach
- Instituto de Biomedicina de Valencia, Consejo Superior de Investigaciones Científicas (IBV-CSIC), Valencia, Spain
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43
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Abstract
In Drosophila, dosage compensation of the single male X chromosome involves upregulation of expression of X linked genes. Dosage compensation complex or the male specific lethal (MSL) complex is intimately involved in this regulation. The MSL complex members decorate the male X chromosome by binding on hundreds of sites along the X chromosome. Recent genome wide analysis has brought new light into X chromosomal regulation. It is becoming increasingly clear that although the X chromosome achieves male specific regulation via the MSL complex members, a number of general factors also impinge on this regulation. Future studies integrating these aspects promise to shed more light into this epigenetic phenomenon.
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Abstract
In many eukaryotic organisms, gender is determined by a pair of heteromorphic sex chromosomes. Degeneration of the non-recombining Y chromosome is a general facet of sex chromosome evolution. Selective pressure to restore expression levels of X-linked genes relative to autosomes accompanies Y-chromosome degeneration, thus driving the evolution of dosage compensation mechanisms. This review focuses on evolutionary aspects of dosage compensation, in light of recent advances in comparative and functional genomics that have substantially increased our understanding of the molecular mechanisms of dosage compensation and how it evolved. We review processes involved in sex chromosome evolution, and discuss the dynamic interaction between Y degeneration and the acquisition of dosage compensation. We compare mechanisms of dosage compensation and the origin of dosage compensation genes between different taxa and comment on sex chromosomes that apparently lack compensation mechanisms. Finally, we discuss how dosage compensation systems can also influence the evolution of well-established sex chromosomes.
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Affiliation(s)
- Beatriz Vicoso
- Department of Integrative Biology, University of California Berkeley, Berkeley, CA 94720, USA.
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Lucchesi JC. The structure-function link of compensated chromatin in Drosophila. Curr Opin Genet Dev 2009; 19:550-6. [PMID: 19880310 DOI: 10.1016/j.gde.2009.10.004] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2009] [Revised: 09/04/2009] [Accepted: 10/07/2009] [Indexed: 01/26/2023]
Abstract
All the aspects of transcription are controlled by complexes that modify or remodel chromatin at the level of individual genes, gene clusters, or whole chromosomes. The MSL complex that is responsible for dosage compensation in Drosophila is an example of complexes that operate at the whole-chromosome level on the transcription of individual genes. Recent experiments using traditional genetic analysis, molecular cytology, chromatin immunoprecipitation, or microarray technology have characterized the function of the two known enzymatic components of the MSL core complex and have identified the sequence characteristics that allow spreading of the complex along the X chromosome and a specific histone modification of active X-linked genes to which it is attracted. Further progress in understanding the function of this complex will benefit from biophysical approaches.
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Kind J, Vaquerizas JM, Gebhardt P, Gentzel M, Luscombe NM, Bertone P, Akhtar A. Genome-wide analysis reveals MOF as a key regulator of dosage compensation and gene expression in Drosophila. Cell 2008; 133:813-28. [PMID: 18510926 DOI: 10.1016/j.cell.2008.04.036] [Citation(s) in RCA: 124] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2007] [Revised: 03/10/2008] [Accepted: 04/29/2008] [Indexed: 12/18/2022]
Abstract
Dosage compensation, mediated by the MSL complex, regulates X-chromosomal gene expression in Drosophila. Here we report that the histone H4 lysine 16 (H4K16) specific histone acetyltransferase MOF displays differential binding behavior depending on whether the target gene is located on the X chromosome versus the autosomes. More specifically, on the male X chromosome, where MSL1 and MSL3 are preferentially associated with the 3' end of dosage compensated genes, MOF displays a bimodal distribution binding to promoters and the 3' ends of genes. In contrast, on MSL1/MSL3 independent X-linked genes and autosomal genes in males and females, MOF binds primarily to promoters. Binding of MOF to autosomes is functional, as H4K16 acetylation and the transcription levels of a number of genes are affected upon MOF depletion. Therefore, MOF is not only involved in the onset of dosage compensation, but also acts as a regulator of gene expression in the Drosophila genome.
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Affiliation(s)
- Jop Kind
- Gene Expression Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany
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47
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Abstract
In Drosophila, dosage compensation augments X chromosome-linked transcription in males relative to females. This process is achieved by the Dosage Compensation Complex (DCC), which associates specifically with the male X chromosome. We previously found that the morphology of this chromosome is sensitive to the amounts of the heterochromatin-associated protein SU(VAR)3-7. In this study, we examine the impact of change in levels of SU(VAR)3-7 on dosage compensation. We first demonstrate that the DCC makes the X chromosome a preferential target for heterochromatic markers. In addition, reduced or increased amounts of SU(VAR)3-7 result in redistribution of the DCC proteins MSL1 and MSL2, and of Histone 4 acetylation of lysine 16, indicating that a wild-type dose of SU(VAR)3-7 is required for X-restricted DCC targeting. SU(VAR)3-7 is also involved in the dosage compensated expression of the X-linked white gene. Finally, we show that absence of maternally provided SU(VAR)3-7 renders dosage compensation toxic in males, and that global amounts of heterochromatin affect viability of ectopic MSL2-expressing females. Taken together, these results bring to light a link between heterochromatin and dosage compensation. In Drosophila, females have two X chromosomes and males only one. The difference in the dose of X-associated genes is compensated by male-specific protein machinery, the Dosage Compensation Complex (DCC), which augments the activity of genes of the single male X. We report that the specific targeting of the DCC on the male X chromosome depends critically on the correct dose of the SU(VAR)3-7 protein. This protein was previously known to associate with condensed and silenced regions of the chromosomes called heterochromatin by contrast with the active form of chromatin called euchromatin. Loss of SU(VAR)3-7 in males causes displacement of the DCC to heterochromatin and bloating of the X chromosome. In contrast, excess of SU(VAR)3-7 leads to a delocalization of the DCC to other chromosomes and to massive shrinking of the X chromosome. We show that SU(VAR)3-7 is involved in the dosage compensated expression of the X-linked white gene and in the viability of dosage compensated flies. Altogether, these results bring to light a link between silencing mechanisms of heterochromatin and mechanisms controlling the balance of sex-chromosome activity (dosage compensation). This opens new perspectives on how complexes that control the global chromosome organisation impact the fine tuning of gene expression.
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Affiliation(s)
- Anne Spierer
- NCCR “Frontiers in Genetics”, Department of Zoology and Animal Biology, University of Geneva, Geneva, Switzerland
| | - Flora Begeot
- NCCR “Frontiers in Genetics”, Department of Zoology and Animal Biology, University of Geneva, Geneva, Switzerland
| | - Pierre Spierer
- NCCR “Frontiers in Genetics”, Department of Zoology and Animal Biology, University of Geneva, Geneva, Switzerland
- * E-mail:
| | - Marion Delattre
- NCCR “Frontiers in Genetics”, Department of Zoology and Animal Biology, University of Geneva, Geneva, Switzerland
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48
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Abstract
Epigenetics describes changes in genome function that occur without a change in the DNA sequence. Dosage compensation is a prime example of the regulation of gene expression by an epigenetic mechanism. Dosage compensation has evolved to balance the expression of sex-linked genes in males and females, which possess different numbers of sex chromosomes. However, the genetic sequence of the chromosomes is the same in both sexes. This mechanism therefore needs (1) to function in a sex-specific manner, (2) to target the sex chromosome from amongst the autosomes and (3) to establish and maintain through development a precise, equalised level of gene expression in one sex compared to the other. The process by which dosage compensation is orchestrated has been well characterised in fruit flies and mammals. Although each has evolved a specific dosage-compensation mechanism, these systems share some underlying themes; the molecular components that mediate dosage compensation in both include non-coding RNA molecules, which act as nucleation points for the compensation process. Both systems utilise chromatin-modifying enzymes to remodel large domains of a chromosome. This review will discuss the mechanism of dosage compensation in Drosophila in light of recent developments that have brought into question the previous model of dosage compensation.
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Affiliation(s)
- S Rea
- Gene expression programme, European Molecular Biology Laboratory, Heidelberg, Germany
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Duncan K, Grskovic M, Strein C, Beckmann K, Niggeweg R, Abaza I, Gebauer F, Wilm M, Hentze MW. Sex-lethal imparts a sex-specific function to UNR by recruiting it to the msl-2 mRNA 3' UTR: translational repression for dosage compensation. Genes Dev 2006; 20:368-79. [PMID: 16452508 PMCID: PMC1361707 DOI: 10.1101/gad.371406] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
MSL-2 (male-specific lethal 2) is the limiting component of the Drosophila dosage compensation complex (DCC) that specifically increases transcription from the male X chromosome. Ectopic expression of MSL-2 protein in females causes DCC assembly on both X chromosomes and lethality. Inhibition of MSL-2 synthesis requires the female-specific protein sex-lethal (SXL), which binds to the msl-2 mRNA 5' and 3' untranslated regions (UTRs) and blocks translation through distinct UTR-specific mechanisms. Here, we purify translationally silenced msl-2 mRNPs and identify UNR (upstream of N-ras) as a protein recruited to the 3' UTR by SXL. We demonstrate that SXL requires UNR as a corepressor for 3'-UTR-mediated regulation, imparting a female-specific function to the ubiquitously expressed UNR protein. Our results reveal a novel functional role for UNR as a translational repressor and indicate that UNR is a key component of a "fail-safe" dosage compensation regulatory system that prevents toxic MSL-2 synthesis in female cells.
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Affiliation(s)
- Kent Duncan
- Gene Expression Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
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Gilfillan GD, Straub T, de Wit E, Greil F, Lamm R, van Steensel B, Becker PB. Chromosome-wide gene-specific targeting of the Drosophila dosage compensation complex. Genes Dev 2006; 20:858-70. [PMID: 16547172 PMCID: PMC1475731 DOI: 10.1101/gad.1399406] [Citation(s) in RCA: 140] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The dosage compensation complex (DCC) of Drosophila melanogaster is capable of distinguishing the single male X from the other chromosomes in the nucleus. It selectively interacts in a discontinuous pattern with much of the X chromosome. How the DCC identifies and binds the X, including binding to the many genes that require dosage compensation, is currently unknown. To identify bound genes and attempt to isolate the targeting cues, we visualized male-specific lethal 1 (MSL1) protein binding along the X chromosome by combining chromatin immunoprecipitation with high-resolution microarrays. More than 700 binding regions for the DCC were observed, encompassing more than half the genes found on the X chromosome. In addition, several rare autosomal binding sites were identified. Essential genes are preferred targets, and genes binding high levels of DCC appear to experience the most compensation (i.e., greatest increase in expression). DCC binding clearly favors genes over intergenic regions, and binds most strongly to the 3' end of transcription units. Within the targeted genes, the DCC exhibits a strong preference for exons and coding sequences. Our results demonstrate gene-specific binding of the DCC, and identify several sequence elements that may partly direct its targeting.
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Affiliation(s)
- Gregor D Gilfillan
- Adolf-Butenandt-Institut, Molekularbiologie, Ludwig-Maximilians-Universität München, 80336 München, Germany
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