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McQuarrie DWJ, Alizada A, Nicholson BC, Soller M. Rapid evolution of promoters from germline-specifically expressed genes including transposon silencing factors. BMC Genomics 2024; 25:678. [PMID: 38977960 PMCID: PMC11229233 DOI: 10.1186/s12864-024-10584-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2024] [Accepted: 07/01/2024] [Indexed: 07/10/2024] Open
Abstract
BACKGROUND The piRNA pathway in animal gonads functions as an 'RNA-based immune system', serving to silence transposable elements and prevent inheritance of novel invaders. In Drosophila, this pathway relies on three gonad-specific Argonaute proteins (Argonaute-3, Aubergine and Piwi) that associate with 23-28 nucleotide piRNAs, directing the silencing of transposon-derived transcripts. Transposons constitute a primary driver of genome evolution, yet the evolution of piRNA pathway factors has not received in-depth exploration. Specifically, channel nuclear pore proteins, which impact piRNA processing, exhibit regions of rapid evolution in their promoters. Consequently, the question arises whether such a mode of evolution is a general feature of transposon silencing pathways. RESULTS By employing genomic analysis of coding and promoter regions within genes that function in transposon silencing in Drosophila, we demonstrate that the promoters of germ cell-specific piRNA factors are undergoing rapid evolution. Our findings indicate that rapid promoter evolution is a common trait among piRNA factors engaged in germline silencing across insect species, potentially contributing to gene expression divergence in closely related taxa. Furthermore, we observe that the promoters of genes exclusively expressed in germ cells generally exhibit rapid evolution, with some divergence in gene expression. CONCLUSION Our results suggest that increased germline promoter evolution, in partnership with other factors, could contribute to transposon silencing and evolution of species through differential expression of genes driven by invading transposons.
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Affiliation(s)
- David W J McQuarrie
- School of Biosciences, College of Life and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
- Birmingham Centre for Genome Biology, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Azad Alizada
- Cancer Research UK Cambridge Institute, University of Cambridge, Li Ka Shing Centre, Cambridge, CB2 0RE, UK
| | - Benjamin Czech Nicholson
- Cancer Research UK Cambridge Institute, University of Cambridge, Li Ka Shing Centre, Cambridge, CB2 0RE, UK
| | - Matthias Soller
- School of Biosciences, College of Life and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
- Birmingham Centre for Genome Biology, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
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2
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Joy J, Fusari E, Milán M. Aneuploidy-induced cellular behaviors: Insights from Drosophila. Dev Cell 2024; 59:295-307. [PMID: 38320484 DOI: 10.1016/j.devcel.2023.12.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Revised: 08/09/2023] [Accepted: 12/15/2023] [Indexed: 02/08/2024]
Abstract
A balanced gene complement is crucial for proper cell function. Aneuploidy, the condition of having an imbalanced chromosome set, alters the stoichiometry of gene copy numbers and protein complexes and has dramatic consequences at the cellular and organismal levels. In humans, aneuploidy is associated with different pathological conditions including cancer, microcephaly, mental retardation, miscarriages, and aging. Over the last century, Drosophila has provided a valuable system for studying the consequences of systemic aneuploidies. More recently, it has contributed to the identification and molecular dissection of aneuploidy-induced cellular behaviors and their impact at the tissue and organismal levels. In this perspective, we review this active field of research, first by comparing knowledge from yeast, mouse, and human cells, then by highlighting the contributions of Drosophila. The aim of these discussions was to further our understanding of the functional interplay between aneuploidy, cell physiology, and tissue homeostasis in human development and disease.
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Affiliation(s)
- Jery Joy
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac, 10-12, 08028 Barcelona, Spain
| | - Elena Fusari
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac, 10-12, 08028 Barcelona, Spain
| | - Marco Milán
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac, 10-12, 08028 Barcelona, Spain; Institució Catalana de Recerca i Estudis Avançats (ICREA), Pg. Lluis Companys, 23, 08010 Barcelona, Spain.
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Lv M, Yao Y, Li F, Xu L, Yang L, Gong Q, Xu YZ, Shi Y, Fan YJ, Tang Y. Structural insights reveal the specific recognition of roX RNA by the dsRNA-binding domains of the RNA helicase MLE and its indispensable role in dosage compensation in Drosophila. Nucleic Acids Res 2019; 47:3142-3157. [PMID: 30649456 PMCID: PMC6451107 DOI: 10.1093/nar/gky1308] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Revised: 12/19/2018] [Accepted: 12/24/2018] [Indexed: 02/04/2023] Open
Abstract
In Drosophila, dosage compensation globally upregulates the expression of genes located on male single X-chromosome. Maleless (MLE) helicase plays an essential role to incorporate the roX lncRNA into the dosage compensation complex (MSL-DCC), and such function is essentially dependent on its dsRNA-binding domains (dsRBDs). Here, we report a 2.90Å crystal structure of tandem dsRBDs of MLE in complex with a 55mer stem-loop of roX2 (R2H1). MLE dsRBDs bind to R2H1 cooperatively and interact with two successive minor grooves and a major groove of R2H1, respectively. The recognition of R2H1 by MLE dsRBDs involves both shape- and sequence-specificity. Moreover, dsRBD2 displays a stronger RNA affinity than dsRBD1, and mutations of key residues in either MLE dsRBD remarkably reduce their affinities for roX2 both in vitro and in vivo. In Drosophila, the structure-based mle mutations generated using the CRISPR/Cas9 system, are partially male-lethal and indicate the inter-regulation among the components of the MSL-DCC at multiple levels. Hence, our research provides structural insights into the interactions between MLE dsRBDs and R2H1 and facilitates a deeper understanding of the mechanism by which MLE tandem dsRBDs play an indispensable role in specific recognition of roX and the assembly of the MSL-DCC in Drosophila dosage compensation.
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Affiliation(s)
- Mengqi Lv
- Hefei National Laboratory for Physical Sciences at Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Yixiang Yao
- Hefei National Laboratory for Physical Sciences at Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Fudong Li
- Hefei National Laboratory for Physical Sciences at Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Ling Xu
- Hefei National Laboratory for Physical Sciences at Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Lingna Yang
- Hefei National Laboratory for Physical Sciences at Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Qingguo Gong
- Hefei National Laboratory for Physical Sciences at Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Yong-Zhen Xu
- State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Yunyu Shi
- Hefei National Laboratory for Physical Sciences at Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230026, China.,CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Yu-Jie Fan
- State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Wuhan University, Wuhan 430072, China.,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
| | - Yajun Tang
- Hefei National Laboratory for Physical Sciences at Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230026, China
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Gu L, Walters JR, Knipple DC. Conserved Patterns of Sex Chromosome Dosage Compensation in the Lepidoptera (WZ/ZZ): Insights from a Moth Neo-Z Chromosome. Genome Biol Evol 2017; 9:802-816. [PMID: 28338816 PMCID: PMC5381563 DOI: 10.1093/gbe/evx039] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/01/2017] [Indexed: 02/07/2023] Open
Abstract
Where previously described, patterns of sex chromosome dosage compensation in the Lepidoptera (moths and butterflies) have several unusual characteristics. Other female-heterogametic (ZW/ZZ) species exhibit female Z-linked expression that is reduced compared with autosomal expression and male Z expression. In the Lepidoptera, however, Z expression typically appears balanced between sexes but overall reduced relative to autosomal expression, that is Z ≈ ZZ < AA. This pattern is not easily reconciled with theoretical expectations for the evolution of sex chromosome dosage compensation. Moreover, conflicting results linger due to discrepancies in data analyses and tissues sampled among lepidopterans. To address these issues, we performed RNA-seq to analyze sex chromosome dosage compensation in the codling moth, Cydia pomonella, which is a species from the earliest diverging lepidopteran lineage yet examined for dosage compensation and has a neo-Z chromosome resulting from an ancient Z:autosome fusion. While supported by intraspecific analyses, the Z ≈ ZZ < AA pattern was further evidenced by comparative study using autosomal orthologs of C. pomonella neo-Z genes in outgroup species. In contrast, dosage compensation appears to be absent in reproductive tissues. We thus argue that inclusion of reproductive tissues may explain the incongruence from a prior study on another moth species and that patterns of dosage compensation are likely conserved in the Lepidoptera. Notably, this pattern appears convergent with patterns in eutherian mammals (X ≈ XX < AA). Overall, our results contribute to the notion that the Lepidoptera present challenges both to classical theories regarding the evolution of sex chromosome dosage compensation and the emerging view of the association of dosage compensation with sexual heterogamety.
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Affiliation(s)
- Liuqi Gu
- Department of Entomology, Cornell University, Geneva, NY
| | - James R Walters
- Department of Ecology & Evolutionary Biology, The University of Kansas, Lawrence, KS
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Mujoo K, Hunt CR, Horikoshi N, Pandita TK. A multifaceted role for MOF histone modifying factor in genome maintenance. Mech Ageing Dev 2016; 161:177-180. [PMID: 27038808 DOI: 10.1016/j.mad.2016.03.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Revised: 03/24/2016] [Accepted: 03/28/2016] [Indexed: 11/19/2022]
Abstract
MOF (males absent on the first) was initially identified as a dosage compensation factor in Drosophila that acetylates lysine 16 of histone H4 (H4K16ac) and increased gene transcription from the single copy male X-chromosome. In humans, however, the ortholog of Drosophila MOF has been shown to interact with a range of proteins that extend its potential significance well beyond transcription. For example, recent results indicate MOF is an upstream regulator of the ATM (ataxia-telangiectasia mutated) protein, the loss of which is responsible for ataxia telangiectasia (AT). ATM is a key regulatory kinase that interacts with and phosphorylates multiple substrates that influence critical, cell-cycle control and DNA damage repair pathways in addition to other pathways. Thus, directly or indirectly, MOF may be involved in a wide range of cellular functions. This review will focus on the contribution of MOF to cellular DNA repair and new results that are beginning to examine the in vivo physiological role of MOF.
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Affiliation(s)
- Kalpana Mujoo
- Department of Radiation Oncology, The Houston Methodist Research Institute, Houston, TX 77030, United States
| | - Clayton R Hunt
- Department of Radiation Oncology, The Houston Methodist Research Institute, Houston, TX 77030, United States
| | - Nobuo Horikoshi
- Department of Radiation Oncology, The Houston Methodist Research Institute, Houston, TX 77030, United States
| | - Tej K Pandita
- Department of Radiation Oncology, The Houston Methodist Research Institute, Houston, TX 77030, United States.
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6
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More complex transcriptional regulation and stress response by MOF. Oncogene 2015; 35:2681-3. [PMID: 26434593 DOI: 10.1038/onc.2015.373] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Accepted: 08/12/2015] [Indexed: 12/11/2022]
Abstract
MOF (males absent on the first) was initially discovered as a dosage compensation factor that regulates the epigenetic acetylation of histone H4 lysine 16. In this issue, Sheikh et al. demonstrate that MOF expression is not required for normal kidney tissue function but is required for maintaining transcriptional regulation under conditions of stress. This work along with results from previous investigators highlights the importance of the cell lineage-chromatin modification interaction in determining transcriptional programs and physiological outcomes under normal and stress conditions.
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7
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Milán M, Clemente-Ruiz M, Dekanty A, Muzzopappa M. Aneuploidy and tumorigenesis in Drosophila. Semin Cell Dev Biol 2014; 28:110-5. [DOI: 10.1016/j.semcdb.2014.03.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2014] [Revised: 03/03/2014] [Accepted: 03/10/2014] [Indexed: 12/15/2022]
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8
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Andersen TA, Troelsen KDLL, Larsen LA. Of mice and men: molecular genetics of congenital heart disease. Cell Mol Life Sci 2013; 71:1327-52. [PMID: 23934094 PMCID: PMC3958813 DOI: 10.1007/s00018-013-1430-1] [Citation(s) in RCA: 101] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Revised: 07/16/2013] [Accepted: 07/18/2013] [Indexed: 12/21/2022]
Abstract
Congenital heart disease (CHD) affects nearly 1 % of the population. It is a complex disease, which may be caused by multiple genetic and environmental factors. Studies in human genetics have led to the identification of more than 50 human genes, involved in isolated CHD or genetic syndromes, where CHD is part of the phenotype. Furthermore, mapping of genomic copy number variants and exome sequencing of CHD patients have led to the identification of a large number of candidate disease genes. Experiments in animal models, particularly in mice, have been used to verify human disease genes and to gain further insight into the molecular pathology behind CHD. The picture emerging from these studies suggest that genetic lesions associated with CHD affect a broad range of cellular signaling components, from ligands and receptors, across down-stream effector molecules to transcription factors and co-factors, including chromatin modifiers.
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Affiliation(s)
- Troels Askhøj Andersen
- Wilhelm Johannsen Centre for Functional Genome Research, Department of Cellular and Molecular Medicine, University of Copenhagen, Blegdamsvej 3, 2200, Copenhagen, Denmark
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9
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Jennings BH. Pausing for thought: disrupting the early transcription elongation checkpoint leads to developmental defects and tumourigenesis. Bioessays 2013; 35:553-60. [PMID: 23575664 PMCID: PMC3698693 DOI: 10.1002/bies.201200179] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Accepted: 03/04/2013] [Indexed: 12/30/2022]
Abstract
Factors affecting transcriptional elongation have been characterized extensively in in vitro, single cell (yeast) and cell culture systems; however, data from the context of multicellular organisms has been relatively scarce. While studies in homogeneous cell populations have been highly informative about the underlying molecular mechanisms and prevalence of polymerase pausing, they do not reveal the biological impact of perturbing this regulation in an animal. The core components regulating pausing are expressed in all animal cells and are recruited to the majority of genes, however, disrupting their function often results in discrete phenotypic effects. Mutations in genes encoding key regulators of transcriptional pausing have been recovered from several genetic screens for specific phenotypes or interactions with specific factors in mice, zebrafish and flies. Analysis of these mutations has revealed that control of transcriptional pausing is critical for a diverse range of biological pathways essential for animal development and survival.
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10
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White-Cooper H, Caporilli S. Transcriptional and post-transcriptional regulation of Drosophila germline stem cells and their differentiating progeny. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013; 786:47-61. [PMID: 23696351 DOI: 10.1007/978-94-007-6621-1_4] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
In this chapter we will concentrate on the transcriptional and translational regulations that govern the development and differentiation of male germline cells. Our focus will be on the processes that occur during differentiation, that distinguish the differentiating population of cells from their stem cell parents. We discuss how these defining features are established as cells transit from a stem cell character to that of a fully committed differentiating cell. The focus will be on how GSCs differentiate, via spermatogonia, to spermatocytes. We will achieve this by first describing the transcriptional activity in the differentiating spermatocytes, cataloguing the known transcriptional regulators in these cells and then investigating how the transcription programme is set up by processes in the progentior cells. This process is particularly interesting to study from a stem cell perspective as the male GSCs are unipotent, so lineage decisions in differentiating progeny of stem cells, which occurs in many other stem cell systems, do not impinge on the behaviour of these cells.
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Abstract
Epigenetics is a major field of biomedical research, and epigenetic drug discovery shows great promise for new drugs. The first epigenetic inhibitors are already approved for human treatment. Here, we review a number of case studies that cover different aspects of epigenetic drug discovery spanning from sequencing of epigenetic modifications, assays development over screening to medicinal chemistry, in vivo testing and clinical application.
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12
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Contrepois K, Thuret JY, Courbeyrette R, Fenaille F, Mann C. Deacetylation of H4-K16Ac and heterochromatin assembly in senescence. Epigenetics Chromatin 2012; 5:15. [PMID: 22932127 PMCID: PMC3487866 DOI: 10.1186/1756-8935-5-15] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2012] [Accepted: 08/02/2012] [Indexed: 01/20/2023] Open
Abstract
Background Cellular senescence is a stress response of mammalian cells leading to a durable arrest of cell proliferation that has been implicated in tumor suppression, wound healing, and aging. The proliferative arrest is mediated by transcriptional repression of genes essential for cell division by the retinoblastoma protein family. This repression is accompanied by varying degrees of heterochromatin assembly, but little is known regarding the molecular mechanisms involved. Results We found that both deacetylation of H4-K16Ac and expression of HMGA1/2 can contribute to DNA compaction during senescence. SIRT2, an NAD-dependent class III histone deacetylase, contributes to H4-K16Ac deacetylation and DNA compaction in human fibroblast cell lines that assemble striking senescence-associated heterochromatin foci (SAHFs). Decreased H4-K16Ac was observed in both replicative and oncogene-induced senescence of these cells. In contrast, this mechanism was inoperative in a fibroblast cell line that did not assemble extensive heterochromatin during senescence. Treatment of senescent cells with trichostatin A, a class I/II histone deacetylase inhibitor, also induced rapid and reversible decondensation of SAHFs. Inhibition of DNA compaction did not significantly affect the stability of the senescent state. Conclusions Variable DNA compaction observed during senescence is explained in part by cell-type specific regulation of H4 deacetylation and HMGA1/2 expression. Deacetylation of H4-K16Ac during senescence may explain reported decreases in this mark during mammalian aging and in cancer cells.
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Affiliation(s)
- Kévin Contrepois
- CEA, iBiTecS, Service de Biologie Intégrative et de Génétique Moléculaire (SBIGeM), F-91191, Gif-sur-Yvette, France.
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WANG YY, CHEN M, LI B. Dosage compensation mechanism of X chromosome. YI CHUAN = HEREDITAS 2012; 34:977-84. [DOI: 10.3724/sp.j.1005.2012.00977] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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14
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Shilatifard A. The COMPASS family of histone H3K4 methylases: mechanisms of regulation in development and disease pathogenesis. Annu Rev Biochem 2012; 81:65-95. [PMID: 22663077 PMCID: PMC4010150 DOI: 10.1146/annurev-biochem-051710-134100] [Citation(s) in RCA: 768] [Impact Index Per Article: 64.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The Saccharomyces cerevisiae Set1/COMPASS was the first histone H3 lysine 4 (H3K4) methylase identified over 10 years ago. Since then, it has been demonstrated that Set1/COMPASS and its enzymatic product, H3K4 methylation, is highly conserved across the evolutionary tree. Although there is only one COMPASS in yeast, Drosophila possesses three and humans bear six COMPASS family members, each capable of methylating H3K4 with nonredundant functions. In yeast, the histone H2B monoubiquitinase Rad6/Bre1 is required for proper H3K4 and H3K79 trimethylations. The machineries involved in this process are also highly conserved from yeast to human. In this review, the process of histone H2B monoubiquitination-dependent and -independent histone H3K4 methylation as a mark of active transcription, enhancer signatures, and developmentally poised genes is discussed. The misregulation of histone H2B monoubiquitination and H3K4 methylation result in the pathogenesis of human diseases, including cancer. Recent findings in this regard are also examined.
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Affiliation(s)
- Ali Shilatifard
- Stowers Institute for Medical Research, Kansas City, Missouri 64110, USA.
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15
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Affiliation(s)
- Denise P. Barlow
- CeMM, Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria;
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16
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Jeon Y, Lee JT. YY1 tethers Xist RNA to the inactive X nucleation center. Cell 2011; 146:119-33. [PMID: 21729784 DOI: 10.1016/j.cell.2011.06.026] [Citation(s) in RCA: 382] [Impact Index Per Article: 29.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2010] [Revised: 03/27/2011] [Accepted: 06/14/2011] [Indexed: 12/16/2022]
Abstract
The long noncoding Xist RNA inactivates one X chromosome in the female mammal. Current models posit that Xist induces silencing as it spreads along X and recruits Polycomb complexes. However, the mechanisms for Xist loading and spreading are currently unknown. Here, we define the nucleation center for Xist RNA and show that YY1 docks Xist particles onto the X chromosome. YY1 is a "bivalent" protein, capable of binding both RNA and DNA through different sequence motifs. Xist's exclusive attachment to the inactive X is determined by an epigenetically regulated trio of YY1 sites as well as allelic origin. Specific YY1-to-RNA and YY1-to-DNA contacts are required to load Xist particles onto X. YY1 interacts with Xist RNA through Repeat C. We propose that YY1 acts as adaptor between regulatory RNA and chromatin targets.
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Affiliation(s)
- Yesu Jeon
- Howard Hughes Medical Institute, Department of Molecular Biology, Massachusetts General Hospital and Department of Genetics, Harvard Medical School, Boston, MA 02114, USA
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17
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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] [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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Graindorge A, Militti C, Gebauer F. Posttranscriptional control of X-chromosome dosage compensation. WILEY INTERDISCIPLINARY REVIEWS-RNA 2011; 2:534-45. [PMID: 21957042 DOI: 10.1002/wrna.75] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
RNA regulation plays a major role in the generation of diversity at the molecular and cellular levels, and furnishes the cell with flexibility potential to adapt to changing environments. Often, the regulation by/of RNA dictates when, where, and how the information encoded in the nucleus is revealed. One example is the regulation of X-chromosome dosage compensation. In Drosophila, differences in X-linked gene dosage between males and females are compensated by the transcriptional upregulation of the single male X chromosome. Mechanisms of alternative splicing and translational control, among others, enforce dosage compensation in males while inhibiting this process in females. In this review, we discuss the posttranscriptional RNA regulatory mechanisms that ensure appropriate dosage compensation in Drosophila, drawing parallels with the mammalian system when appropriate.
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Affiliation(s)
- Antoine Graindorge
- Gene Regulation Programme, Centre for Genomic Regulation (CRG), UPF, Barcelona, Spain
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19
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Eaton ML, Prinz JA, MacAlpine HK, Tretyakov G, Kharchenko PV, MacAlpine DM. Chromatin signatures of the Drosophila replication program. Genome Res 2010; 21:164-74. [PMID: 21177973 DOI: 10.1101/gr.116038.110] [Citation(s) in RCA: 147] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
DNA replication initiates from thousands of start sites throughout the Drosophila genome and must be coordinated with other ongoing nuclear processes such as transcription to ensure genetic and epigenetic inheritance. Considerable progress has been made toward understanding how chromatin modifications regulate the transcription program; in contrast, we know relatively little about the role of the chromatin landscape in defining how start sites of DNA replication are selected and regulated. Here, we describe the Drosophila replication program in the context of the chromatin and transcription landscape for multiple cell lines using data generated by the modENCODE consortium. We find that while the cell lines exhibit similar replication programs, there are numerous cell line-specific differences that correlate with changes in the chromatin architecture. We identify chromatin features that are associated with replication timing, early origin usage, and ORC binding. Primary sequence, activating chromatin marks, and DNA-binding proteins (including chromatin remodelers) contribute in an additive manner to specify ORC-binding sites. We also generate accurate and predictive models from the chromatin data to describe origin usage and strength between cell lines. Multiple activating chromatin modifications contribute to the function and relative strength of replication origins, suggesting that the chromatin environment does not regulate origins of replication as a simple binary switch, but rather acts as a tunable rheostat to regulate replication initiation events.
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Affiliation(s)
- Matthew L Eaton
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710, USA
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