1
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Anyetei-Anum CS, Leatham-Jensen MP, Fox GC, Smith BR, Chirasani VR, Krajewski K, Strahl BD, Dowen JM, Matera AG, Duronio RJ, McKay DJ. Evidence for dual roles of histone H3 lysine 4 in antagonizing Polycomb group function and promoting target gene expression. Genes Dev 2024; 38:1033-1046. [PMID: 39562140 PMCID: PMC11610931 DOI: 10.1101/gad.352181.124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2024] [Accepted: 11/05/2024] [Indexed: 11/21/2024]
Abstract
Tight control over cell identity gene expression is necessary for proper adult form and function. The opposing activities of Polycomb and trithorax complexes determine the on/off state of cell identity genes such as the Hox factors. Polycomb group complexes repress target genes, whereas trithorax group complexes are required for their expression. Although trithorax and its orthologs function as methyltransferases specific to histone H3 lysine 4 (H3K4), there is no direct evidence that H3K4 regulates Polycomb group target genes in vivo. Using histone gene replacement in Drosophila, we provide evidence of two key roles for replication-dependent histone H3.2K4 in Polycomb target gene control. First, we found that H3.2K4 mutants mimic H3.2K4me3 in antagonizing methyltransferase activity of the PRC2 Polycomb group complex. Second, we found that H3.2K4 is also required for proper activation of Polycomb targets. We conclude that H3.2K4 directly regulates Polycomb target gene expression.
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Affiliation(s)
- Cyril S Anyetei-Anum
- Curriculum in Genetics and Molecular Biology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
| | - Mary P Leatham-Jensen
- Integrative Program for Biological and Genome Sciences, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
| | - Geoffrey C Fox
- Curriculum in Genetics and Molecular Biology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
| | - B Rutledge Smith
- Department of Biology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
| | - Venkat R Chirasani
- Department of Biochemistry and Biophysics, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
| | - Krzysztof Krajewski
- Department of Biochemistry and Biophysics, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
| | - Brian D Strahl
- Curriculum in Genetics and Molecular Biology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
- Department of Biochemistry and Biophysics, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
- Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
| | - Jill M Dowen
- Curriculum in Genetics and Molecular Biology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
- Integrative Program for Biological and Genome Sciences, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
- Department of Biology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
- Department of Biochemistry and Biophysics, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
- Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
| | - A Gregory Matera
- Curriculum in Genetics and Molecular Biology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
- Integrative Program for Biological and Genome Sciences, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
- Department of Biology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
- Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
- Department of Genetics, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
| | - Robert J Duronio
- Curriculum in Genetics and Molecular Biology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
- Integrative Program for Biological and Genome Sciences, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
- Department of Biology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
- Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
- Department of Genetics, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
| | - Daniel J McKay
- Curriculum in Genetics and Molecular Biology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA;
- Integrative Program for Biological and Genome Sciences, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
- Department of Biology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
- Department of Genetics, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
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2
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Atinbayeva N, Valent I, Zenk F, Loeser E, Rauer M, Herur S, Quarato P, Pyrowolakis G, Gomez-Auli A, Mittler G, Cecere G, Erhardt S, Tiana G, Zhan Y, Iovino N. Inheritance of H3K9 methylation regulates genome architecture in Drosophila early embryos. EMBO J 2024; 43:2685-2714. [PMID: 38831123 PMCID: PMC11217351 DOI: 10.1038/s44318-024-00127-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Revised: 03/27/2024] [Accepted: 04/15/2024] [Indexed: 06/05/2024] Open
Abstract
Constitutive heterochromatin is essential for transcriptional silencing and genome integrity. The establishment of constitutive heterochromatin in early embryos and its role in early fruitfly development are unknown. Lysine 9 trimethylation of histone H3 (H3K9me3) and recruitment of its epigenetic reader, heterochromatin protein 1a (HP1a), are hallmarks of constitutive heterochromatin. Here, we show that H3K9me3 is transmitted from the maternal germline to the next generation. Maternally inherited H3K9me3, and the histone methyltransferases (HMT) depositing it, are required for the organization of constitutive heterochromatin: early embryos lacking H3K9 methylation display de-condensation of pericentromeric regions, centromere-centromere de-clustering, mitotic defects, and nuclear shape irregularities, resulting in embryo lethality. Unexpectedly, quantitative CUT&Tag and 4D microscopy measurements of HP1a coupled with biophysical modeling revealed that H3K9me2/3 is largely dispensable for HP1a recruitment. Instead, the main function of H3K9me2/3 at this developmental stage is to drive HP1a clustering and subsequent heterochromatin compaction. Our results show that HP1a binding to constitutive heterochromatin in the absence of H3K9me2/3 is not sufficient to promote proper embryo development and heterochromatin formation. The loss of H3K9 HMTs and H3K9 methylation alters genome organization and hinders embryonic development.
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Affiliation(s)
- Nazerke Atinbayeva
- Max Planck Institute of Immunobiology and Epigenetics, 79108, Freiburg im Breisgau, Germany
- Albert-Ludwigs-Universität Freiburg, Fahnenbergplatz, 79085, Freiburg im Breisgau, Germany
| | - Iris Valent
- Karlsruhe Institute of Technology (KIT), Zoological Institute, 76131, Karlsruhe, Germany
| | - Fides Zenk
- Brain Mind Institute, School of Life Sciences EPFL, SV3809, 1015, Lausanne, Switzerland
| | - Eva Loeser
- Max Planck Institute of Immunobiology and Epigenetics, 79108, Freiburg im Breisgau, Germany
| | - Michael Rauer
- Max Planck Institute of Immunobiology and Epigenetics, 79108, Freiburg im Breisgau, Germany
| | - Shwetha Herur
- Max Planck Institute of Immunobiology and Epigenetics, 79108, Freiburg im Breisgau, Germany
| | - Piergiuseppe Quarato
- San Raffaele Telethon Institute for Gene Therapy, IRCCS San Raffaele Scientific Institute, 20132, Milan, Italy
| | - Giorgos Pyrowolakis
- Centre for Biological signaling studies, University of Freiburg, 79104, Freiburg im Breisgau, Germany
| | - Alejandro Gomez-Auli
- Max Planck Institute of Immunobiology and Epigenetics, 79108, Freiburg im Breisgau, Germany
| | - Gerhard Mittler
- Max Planck Institute of Immunobiology and Epigenetics, 79108, Freiburg im Breisgau, Germany
| | - Germano Cecere
- Institute Pasteur, Mechanisms of Epigenetic Inheritance, Department of Developmental and Stem Cell Biology, UMR3738, CNRS, 75724, Cedex 15, Paris, France
| | - Sylvia Erhardt
- Karlsruhe Institute of Technology (KIT), Zoological Institute, 76131, Karlsruhe, Germany
| | - Guido Tiana
- Università degli Studi di Milano and INFN, Milan, Italy
| | - Yinxiu Zhan
- Department of Experimental Oncology, European Institute of Oncology-IRCCS, Milan, Italy.
| | - Nicola Iovino
- Max Planck Institute of Immunobiology and Epigenetics, 79108, Freiburg im Breisgau, Germany.
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3
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Stutzman AV, Hill CA, Armstrong RL, Gohil R, Duronio RJ, Dowen JM, McKay DJ. Heterochromatic 3D genome organization is directed by HP1a- and H3K9-dependent and independent mechanisms. Mol Cell 2024; 84:2017-2035.e6. [PMID: 38795706 PMCID: PMC11185254 DOI: 10.1016/j.molcel.2024.05.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Revised: 03/07/2024] [Accepted: 05/02/2024] [Indexed: 05/28/2024]
Abstract
Whether and how histone post-translational modifications and the proteins that bind them drive 3D genome organization remains unanswered. Here, we evaluate the contribution of H3K9-methylated constitutive heterochromatin to 3D genome organization in Drosophila tissues. We find that the predominant organizational feature of wild-type tissues is the segregation of euchromatic chromosome arms from heterochromatic pericentromeres. Reciprocal perturbation of HP1a⋅H3K9me binding, using a point mutation in the HP1a chromodomain or replacement of the replication-dependent histone H3 with H3K9R mutant histones, revealed that HP1a binding to methylated H3K9 in constitutive heterochromatin is required to limit contact frequency between pericentromeres and chromosome arms and regulate the distance between arm and pericentromeric regions. Surprisingly, the self-association of pericentromeric regions is largely preserved despite the loss of H3K9 methylation and HP1a occupancy. Thus, the HP1a⋅H3K9 interaction contributes to but does not solely drive the segregation of euchromatin and heterochromatin inside the nucleus.
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Affiliation(s)
- Alexis V Stutzman
- Curriculum in Genetics & Molecular Biology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Christina A Hill
- Integrative Program for Biological and Genome Sciences, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Robin L Armstrong
- Curriculum in Genetics & Molecular Biology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Riya Gohil
- Curriculum in Genetics & Molecular Biology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Robert J Duronio
- Integrative Program for Biological and Genome Sciences, University of North Carolina, Chapel Hill, NC 27599, USA; Department of Biology, University of North Carolina, Chapel Hill, NC 27599, USA; Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, USA; Department of Genetics, University of North Carolina, Chapel Hill, NC 27599, USA.
| | - Jill M Dowen
- Integrative Program for Biological and Genome Sciences, University of North Carolina, Chapel Hill, NC 27599, USA; Department of Biology, University of North Carolina, Chapel Hill, NC 27599, USA; Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, USA; Department of Biochemistry & Biophysics, University of North Carolina, Chapel Hill, NC 27599, USA.
| | - Daniel J McKay
- Integrative Program for Biological and Genome Sciences, University of North Carolina, Chapel Hill, NC 27599, USA; Department of Biology, University of North Carolina, Chapel Hill, NC 27599, USA; Department of Genetics, University of North Carolina, Chapel Hill, NC 27599, USA.
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4
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Brown JC, McMichael BD, Vandadi V, Mukherjee A, Salzler HR, Matera AG. Lysine-36 of Drosophila histone H3.3 supports adult longevity. G3 (BETHESDA, MD.) 2024; 14:jkae030. [PMID: 38366796 PMCID: PMC10989886 DOI: 10.1093/g3journal/jkae030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Revised: 01/16/2023] [Accepted: 02/04/2024] [Indexed: 02/18/2024]
Abstract
Aging is a multifactorial process that disturbs homeostasis, increases disease susceptibility, and ultimately results in death. Although the definitive set of molecular mechanisms responsible for aging remain to be discovered, epigenetic change over time is proving to be a promising piece of the puzzle. Several post-translational histone modifications have been linked to the maintenance of longevity. Here, we focus on lysine-36 of the replication-independent histone protein, H3.3 (H3.3K36). To interrogate the role of this residue in Drosophila developmental gene regulation, we generated a lysine-to-arginine mutant that blocks the activity of its cognate-modifying enzymes. We found that an H3.3BK36R mutation causes a significant reduction in adult lifespan, accompanied by dysregulation of the genomic and transcriptomic architecture. Transgenic co-expression of wild-type H3.3B completely rescues the longevity defect. Because H3.3 is known to accumulate in nondividing tissues, we carried out transcriptome profiling of young vs aged adult fly heads. The data show that loss of H3.3K36 results in age-dependent misexpression of NF-κB and other innate immune target genes, as well as defects in silencing of heterochromatin. We propose H3.3K36 maintains the postmitotic epigenomic landscape, supporting longevity by regulating both pericentric and telomeric retrotransposons and by suppressing aberrant immune signaling.
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Affiliation(s)
- John C Brown
- Integrative Program for Biological and Genome Sciences, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Benjamin D McMichael
- Integrative Program for Biological and Genome Sciences, University of North Carolina, Chapel Hill, NC 27599, USA
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Vasudha Vandadi
- Integrative Program for Biological and Genome Sciences, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Aadit Mukherjee
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Harmony R Salzler
- Integrative Program for Biological and Genome Sciences, University of North Carolina, Chapel Hill, NC 27599, USA
| | - A Gregory Matera
- Integrative Program for Biological and Genome Sciences, University of North Carolina, Chapel Hill, NC 27599, USA
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599, USA
- Department of Genetics, University of North Carolina, Chapel Hill, NC 27599, USA
- RNA Discovery Center, Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, USA
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5
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Koryakov DE. Diversity and functional specialization of H3K9-specific histone methyltransferases. Bioessays 2024; 46:e2300163. [PMID: 38058121 DOI: 10.1002/bies.202300163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2023] [Revised: 11/16/2023] [Accepted: 11/20/2023] [Indexed: 12/08/2023]
Abstract
Histone modifications play a critical role in the control over activities of the eukaryotic genome; among these chemical alterations, the methylation of lysine K9 in histone H3 (H3K9) is one of the most extensively studied. The number of enzymes capable of methylating H3K9 varies greatly across different organisms: in fission yeast, only one such methyltransferase is present, whereas in mammals, 10 are known. If there are several such enzymes, each of them must have some specific function, and they can interact with one another. Thus arises a complex system of interchangeability, "division of labor," and contacts with each other and with diverse proteins. Histone methyltransferases specialize in the number of methyl groups that they attach and have different intracellular localizations as well as different distributions on chromosomes. Each also shows distinct binding to different types of sequences and has a specific set of nonhistone substrates.
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Affiliation(s)
- Dmitry E Koryakov
- Lab of Molecular Cytogenetics, Institute of Molecular and Cellular Biology, Novosibirsk, Russia
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6
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Romanov SE, Shloma VV, Maksimov DA, Koryakov DE. SetDB1 and Su(var)3-9 are essential for late stages of larval development of Drosophila melanogaster. Chromosome Res 2023; 31:35. [PMID: 38099968 DOI: 10.1007/s10577-023-09743-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Revised: 10/25/2023] [Accepted: 11/02/2023] [Indexed: 12/18/2023]
Abstract
Methylation of H3K9 histone residue is a marker of gene silencing in eukaryotes. Three enzymes responsible for adding this modification - G9a, SetDB1/Egg, and Su(var)3-9 - are known in Drosophila. To understand how simultaneous mutations of SetDB1 and Su(var)3-9 may affect the fly development, appropriate combinations were obtained. Double mutants egg; Su(var)3-9 displayed pronounced embryonic lethality, slower larval growth and died before or during metamorphosis. Analysis of transcription in larval salivary glands and wing imaginal disks indicated that the effect of double mutation is tissue-specific. In salivary gland chromosomes, affected genes display low H3K9me2 enrichment and are rarely bound by SetDB1 or Su(var)3-9. We suppose that each of these enzymes directly or indirectly controls its own set of gene targets in different organs, and double mutation results in an imbalanced developmental program. This also indicates that SetDB1 and Su(var)3-9 may affect transcription via H3K9-independent mechanisms. Unexpectedly, in double and triple mutants, amount of di- and tri-methylated H3K9 is drastically reduced, but not completely absent. We hypothesize that this residual methylation implies the existence of additional H3K9-specific methyltransferase in Drosophila.
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Affiliation(s)
- Stanislav E Romanov
- Institute of Molecular and Cellular Biology SB RAS, Novosibirsk, 630090, Russia
| | - Viktor V Shloma
- Institute of Molecular and Cellular Biology SB RAS, Novosibirsk, 630090, Russia
| | - Daniil A Maksimov
- Institute of Molecular and Cellular Biology SB RAS, Novosibirsk, 630090, Russia
| | - Dmitry E Koryakov
- Institute of Molecular and Cellular Biology SB RAS, Novosibirsk, 630090, Russia.
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7
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Brown JC, McMichael BD, Vandadi V, Mukherjee A, Salzler HR, Matera AG. Lysine-36 of Drosophila histone H3.3 supports adult longevity. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.28.559962. [PMID: 38196611 PMCID: PMC10775331 DOI: 10.1101/2023.09.28.559962] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2024]
Abstract
Aging is a multifactorial process that disturbs homeostasis, increases disease susceptibility, and ultimately results in death. Although the definitive set of molecular mechanisms responsible for aging remain to be discovered, epigenetic change over time is proving to be a promising piece of the puzzle. Several posttranslational histone modifications (PTMs) have been linked to the maintenance of longevity. Here, we focus on lysine-36 of the replication-independent histone protein, H3.3 (H3.3K36). To interrogate the role of this residue in Drosophila developmental gene regulation, we generated a lysine to arginine mutant that blocks the activity of its cognate modifying enzymes. We found that an H3.3BK36R mutation causes a significant reduction in adult lifespan, accompanied by dysregulation of the genomic and transcriptomic architecture. Transgenic co-expression of wild-type H3.3B completely rescues the longevity defect. Because H3.3 is known to accumulate in non-dividing tissues, we carried out transcriptome profiling of young vs aged adult fly heads. The data show that loss of H3.3K36 results in age-dependent misexpression of NF-κB and other innate immune target genes, as well as defects in silencing of heterochromatin. We propose H3.3K36 maintains the postmitotic epigenomic landscape, supporting longevity by regulating both pericentric and telomeric retrotransposons and by suppressing aberrant immune signaling.
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Affiliation(s)
- John C. Brown
- Integrative Program for Biological and Genome Sciences, University of North Carolina, Chapel Hill, NC, USA
| | - Benjamin D. McMichael
- Integrative Program for Biological and Genome Sciences, University of North Carolina, Chapel Hill, NC, USA
- Department of Biology, University of North Carolina, Chapel Hill, NC, USA
| | - Vasudha Vandadi
- Integrative Program for Biological and Genome Sciences, University of North Carolina, Chapel Hill, NC, USA
| | - Aadit Mukherjee
- Department of Biology, University of North Carolina, Chapel Hill, NC, USA
| | - Harmony R. Salzler
- Integrative Program for Biological and Genome Sciences, University of North Carolina, Chapel Hill, NC, USA
| | - A. Gregory Matera
- Integrative Program for Biological and Genome Sciences, University of North Carolina, Chapel Hill, NC, USA
- Department of Biology, University of North Carolina, Chapel Hill, NC, USA
- Department of Genetics, University of North Carolina, Chapel Hill, NC, USA
- RNA Discovery Center, Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, USA
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8
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Salzler HR, Vandadi V, McMichael BD, Brown JC, Boerma SA, Leatham-Jensen MP, Adams KM, Meers MP, Simon JM, Duronio RJ, McKay DJ, Matera AG. Distinct roles for canonical and variant histone H3 lysine-36 in Polycomb silencing. SCIENCE ADVANCES 2023; 9:eadf2451. [PMID: 36857457 PMCID: PMC9977188 DOI: 10.1126/sciadv.adf2451] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Accepted: 01/31/2023] [Indexed: 05/26/2023]
Abstract
Polycomb complexes regulate cell type-specific gene expression programs through heritable silencing of target genes. Trimethylation of histone H3 lysine 27 (H3K27me3) is essential for this process. Perturbation of H3K36 is thought to interfere with H3K27me3. We show that mutants of Drosophila replication-dependent (H3.2K36R) or replication-independent (H3.3K36R) histone H3 genes generally maintain Polycomb silencing and reach later stages of development. In contrast, combined (H3.3K36RH3.2K36R) mutants display widespread Hox gene misexpression and fail to develop past the first larval stage. Chromatin profiling revealed that the H3.2K36R mutation disrupts H3K27me3 levels broadly throughout silenced domains, whereas these regions are mostly unaffected in H3.3K36R animals. Analysis of H3.3 distributions showed that this histone is enriched at presumptive Polycomb response elements located outside of silenced domains but relatively depleted from those inside. We conclude that H3.2 and H3.3 K36 residues collaborate to repress Hox genes using different mechanisms.
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Affiliation(s)
- Harmony R. Salzler
- Integrative Program for Biological and Genome Sciences, University of North Carolina, Chapel Hill, NC, USA
| | - Vasudha Vandadi
- Integrative Program for Biological and Genome Sciences, University of North Carolina, Chapel Hill, NC, USA
| | - Benjamin D. McMichael
- Integrative Program for Biological and Genome Sciences, University of North Carolina, Chapel Hill, NC, USA
- Department of Biology, University of North Carolina, Chapel Hill, NC, USA
| | - John C. Brown
- Integrative Program for Biological and Genome Sciences, University of North Carolina, Chapel Hill, NC, USA
| | - Sally A. Boerma
- Department of Biology, Carleton College, Northfield, MN, USA
| | - Mary P. Leatham-Jensen
- Integrative Program for Biological and Genome Sciences, University of North Carolina, Chapel Hill, NC, USA
| | - Kirsten M. Adams
- Department of Biology, University of North Carolina, Chapel Hill, NC, USA
| | - Michael P. Meers
- Integrative Program for Biological and Genome Sciences, University of North Carolina, Chapel Hill, NC, USA
- Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, NC, USA
| | - Jeremy M. Simon
- Department of Genetics, University of North Carolina, Chapel Hill, NC, USA
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, USA
| | - Robert J. Duronio
- Integrative Program for Biological and Genome Sciences, University of North Carolina, Chapel Hill, NC, USA
- Department of Biology, University of North Carolina, Chapel Hill, NC, USA
- Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, NC, USA
- Department of Genetics, University of North Carolina, Chapel Hill, NC, USA
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, USA
| | - Daniel J. McKay
- Integrative Program for Biological and Genome Sciences, University of North Carolina, Chapel Hill, NC, USA
- Department of Biology, University of North Carolina, Chapel Hill, NC, USA
- Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, NC, USA
- Department of Genetics, University of North Carolina, Chapel Hill, NC, USA
| | - A. Gregory Matera
- Integrative Program for Biological and Genome Sciences, University of North Carolina, Chapel Hill, NC, USA
- Department of Biology, University of North Carolina, Chapel Hill, NC, USA
- Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, NC, USA
- Department of Genetics, University of North Carolina, Chapel Hill, NC, USA
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, USA
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9
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Corcoran ET, Jacob Y. Direct assessment of histone function using histone replacement. Trends Biochem Sci 2023; 48:53-70. [PMID: 35853806 PMCID: PMC9789166 DOI: 10.1016/j.tibs.2022.06.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Revised: 06/15/2022] [Accepted: 06/22/2022] [Indexed: 02/09/2023]
Abstract
Histones serve many purposes in eukaryotic cells in the regulation of diverse genomic processes, including transcription, replication, DNA repair, and chromatin organization. As such, experimental systems to assess histone function are fundamental resources toward elucidating the regulation of activities occurring on chromatin. One set of important tools for investigating histone function are histone replacement systems, in which endogenous histone expression can be partially or completely replaced with a mutant histone. Histone replacement systems allow systematic screens of histone regulatory functions and the direct assessment of functions for histone residues. In this review, we describe existing histone replacement systems in model organisms, the benefits and limitations of these systems, and opportunities for future research with histone replacement strategies.
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Affiliation(s)
- Emma Tung Corcoran
- Yale University, Department of Molecular, Cellular and Developmental Biology, Faculty of Arts and Sciences, 260 Whitney Avenue, New Haven, CT 06511, USA
| | - Yannick Jacob
- Yale University, Department of Molecular, Cellular and Developmental Biology, Faculty of Arts and Sciences, 260 Whitney Avenue, New Haven, CT 06511, USA.
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10
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Crain AT, Klusza S, Armstrong RL, Santa Rosa P, Temple BRS, Strahl BD, McKay DJ, Matera AG, Duronio RJ. Distinct developmental phenotypes result from mutation of Set8/KMT5A and histone H4 lysine 20 in Drosophila melanogaster. Genetics 2022; 221:iyac054. [PMID: 35404465 PMCID: PMC9157153 DOI: 10.1093/genetics/iyac054] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Accepted: 03/28/2022] [Indexed: 01/27/2023] Open
Abstract
Mono-methylation of histone H4 lysine 20 (H4K20me1) is catalyzed by Set8/KMT5A and regulates numerous aspects of genome organization and function. Loss-of-function mutations in Drosophila melanogaster Set8 or mammalian KMT5A prevent H4K20me1 and disrupt development. Set8/KMT5A also has non-histone substrates, making it difficult to determine which developmental functions of Set8/KMT5A are attributable to H4K20me1 and which to other substrates or to non-catalytic roles. Here, we show that human KMT5A can functionally substitute for Set8 during Drosophila development and that the catalytic SET domains of the two enzymes are fully interchangeable. We also uncovered a role in eye development for the N-terminal domain of Set8 that cannot be complemented by human KMT5A. Whereas Set820/20 null mutants are inviable, we found that an R634G mutation in Set8 predicted from in vitro experiments to ablate catalytic activity resulted in viable adults. Additionally, Set8(R634G) mutants retain significant, albeit reduced, H4K20me1, indicating that the R634G mutation does not eliminate catalytic activity in vivo and is functionally hypomorphic rather than null. Flies engineered to express only unmodifiable H4 histones (H4K20A) can also complete development, but are phenotypically distinct from H4K20R, Set820/20 null, and Set8R634G mutants. Taken together, our results demonstrate functional conservation of KMT5A and Set8 enzymes, as well as distinct roles for Set8 and H4K20me1 in Drosophila development.
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Affiliation(s)
- Aaron T Crain
- Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, NC, 27599 USA
- Integrative Program for Biological and Genome Sciences, University of North Carolina, Chapel Hill, NC, 27599 USA
| | - Stephen Klusza
- Integrative Program for Biological and Genome Sciences, University of North Carolina, Chapel Hill, NC, 27599 USA
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, 27599 USA
| | - Robin L Armstrong
- Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, NC, 27599 USA
- Integrative Program for Biological and Genome Sciences, University of North Carolina, Chapel Hill, NC, 27599 USA
| | | | - Brenda R S Temple
- Integrative Program for Biological and Genome Sciences, University of North Carolina, Chapel Hill, NC, 27599 USA
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC, 27599 USA
| | - Brian D Strahl
- Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, NC, 27599 USA
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, 27599 USA
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC, 27599 USA
| | - Daniel J McKay
- Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, NC, 27599 USA
- Integrative Program for Biological and Genome Sciences, University of North Carolina, Chapel Hill, NC, 27599 USA
- Department of Biology, University of North Carolina, Chapel Hill, NC, 27599 USA
- Department of Genetics, University of North Carolina, Chapel Hill, NC, 27599 USA
| | - A Gregory Matera
- Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, NC, 27599 USA
- Integrative Program for Biological and Genome Sciences, University of North Carolina, Chapel Hill, NC, 27599 USA
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, 27599 USA
- Department of Biology, University of North Carolina, Chapel Hill, NC, 27599 USA
- Department of Genetics, University of North Carolina, Chapel Hill, NC, 27599 USA
| | - Robert J Duronio
- Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, NC, 27599 USA
- Integrative Program for Biological and Genome Sciences, University of North Carolina, Chapel Hill, NC, 27599 USA
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, 27599 USA
- Department of Biology, University of North Carolina, Chapel Hill, NC, 27599 USA
- Department of Genetics, University of North Carolina, Chapel Hill, NC, 27599 USA
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11
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Nevil M, Duronio RJ. The awesome power of histone genetics. Mol Cell 2021; 81:1593-1595. [PMID: 33861947 PMCID: PMC9531585 DOI: 10.1016/j.molcel.2021.03.023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Using a genetic platform to generate histone mutants in Drosophila, Regadas et al. (2021) discover a novel mechanism for tissue-specific gene expression requiring a chromatin state defined by acetylation of lysine 14 of H3 but lacking other activating histone post-translational modifications.
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Affiliation(s)
- Markus Nevil
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, USA; SPIRE, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Robert J Duronio
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, USA; Integrative Program for Biological and Genome Sciences, University of North Carolina, Chapel Hill, NC 27599, USA; Departments of Biology and Genetics, University of North Carolina, Chapel Hill, NC 27599, USA.
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12
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Abstract
Nucleosomes wrap DNA and impede access for the machinery of transcription. The core histones that constitute nucleosomes are subject to a diversity of posttranslational modifications, or marks, that impact the transcription of genes. Their functions have sometimes been difficult to infer because the enzymes that write and read them are complex, multifunctional proteins. Here, we examine the evidence for the functions of marks and argue that the major marks perform a fairly small number of roles in either promoting transcription or preventing it. Acetylations and phosphorylations on the histone core disrupt histone-DNA contacts and/or destabilize nucleosomes to promote transcription. Ubiquitylations stimulate methylations that provide a scaffold for either the formation of silencing complexes or resistance to those complexes, and carry a memory of the transcriptional state. Tail phosphorylations deconstruct silencing complexes in particular contexts. We speculate that these fairly simple roles form the basis of transcriptional regulation by histone marks.
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Affiliation(s)
- Paul B Talbert
- Howard Hughes Medical Institute, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA;
| | - Steven Henikoff
- Howard Hughes Medical Institute, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA;
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13
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Regadas I, Dahlberg O, Vaid R, Ho O, Belikov S, Dixit G, Deindl S, Wen J, Mannervik M. A unique histone 3 lysine 14 chromatin signature underlies tissue-specific gene regulation. Mol Cell 2021; 81:1766-1780.e10. [PMID: 33631105 DOI: 10.1016/j.molcel.2021.01.041] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 01/27/2021] [Accepted: 01/27/2021] [Indexed: 12/13/2022]
Abstract
Organismal development and cell differentiation critically depend on chromatin state transitions. However, certain developmentally regulated genes lack histone 3 lysine 9 and 27 acetylation (H3K9ac and H3K27ac, respectively) and histone 3 lysine 4 (H3K4) methylation, histone modifications common to most active genes. Here we describe a chromatin state featuring unique histone 3 lysine 14 acetylation (H3K14ac) peaks in key tissue-specific genes in Drosophila and human cells. Replacing H3K14 in Drosophila demonstrates that H3K14 is essential for expression of genes devoid of canonical histone modifications in the embryonic gut and larval wing imaginal disc, causing lethality and defective wing patterning. We find that the SWI/SNF protein Brahma (Brm) recognizes H3K14ac, that brm acts in the same genetic pathway as H3K14R, and that chromatin accessibility at H3K14ac-unique genes is decreased in H3K14R mutants. Our results show that acetylation of a single lysine is essential at genes devoid of canonical histone marks and uncover an important requirement for H3K14 in tissue-specific gene regulation.
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Affiliation(s)
- Isabel Regadas
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, 10691 Stockholm, Sweden
| | - Olle Dahlberg
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, 10691 Stockholm, Sweden
| | - Roshan Vaid
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, 10691 Stockholm, Sweden
| | - Oanh Ho
- Department of Cell and Molecular Biology, Science for Life Laboratory, Uppsala University, 75237, Uppsala, Sweden
| | - Sergey Belikov
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, 10691 Stockholm, Sweden
| | - Gunjan Dixit
- Department of Genome Sciences, The John Curtin School of Medical Research, Australian National University, Canberra, ACT 2600, Australia
| | - Sebastian Deindl
- Department of Cell and Molecular Biology, Science for Life Laboratory, Uppsala University, 75237, Uppsala, Sweden
| | - Jiayu Wen
- Department of Genome Sciences, The John Curtin School of Medical Research, Australian National University, Canberra, ACT 2600, Australia.
| | - Mattias Mannervik
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, 10691 Stockholm, Sweden.
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14
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Reevaluating the roles of histone-modifying enzymes and their associated chromatin modifications in transcriptional regulation. Nat Genet 2020; 52:1271-1281. [PMID: 33257899 DOI: 10.1038/s41588-020-00736-4] [Citation(s) in RCA: 223] [Impact Index Per Article: 44.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2020] [Accepted: 10/08/2020] [Indexed: 12/14/2022]
Abstract
Histone-modifying enzymes are implicated in the control of diverse DNA-templated processes including gene expression. Here, we outline historical and current thinking regarding the functions of histone modifications and their associated enzymes. One current viewpoint, based largely on correlative evidence, posits that histone modifications are instructive for transcriptional regulation and represent an epigenetic 'code'. Recent studies have challenged this model and suggest that histone marks previously associated with active genes do not directly cause transcriptional activation. Additionally, many histone-modifying proteins possess non-catalytic functions that overshadow their enzymatic activities. Given that much remains unknown regarding the functions of these proteins, the field should be cautious in interpreting loss-of-function phenotypes and must consider both cellular and developmental context. In this Perspective, we focus on recent progress relating to the catalytic and non-catalytic functions of the Trithorax-COMPASS complexes, Polycomb repressive complexes and Clr4/Suv39 histone-modifying machineries.
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15
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Meyer-Nava S, Nieto-Caballero VE, Zurita M, Valadez-Graham V. Insights into HP1a-Chromatin Interactions. Cells 2020; 9:E1866. [PMID: 32784937 PMCID: PMC7465937 DOI: 10.3390/cells9081866] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Revised: 07/18/2020] [Accepted: 07/21/2020] [Indexed: 12/17/2022] Open
Abstract
Understanding the packaging of DNA into chromatin has become a crucial aspect in the study of gene regulatory mechanisms. Heterochromatin establishment and maintenance dynamics have emerged as some of the main features involved in genome stability, cellular development, and diseases. The most extensively studied heterochromatin protein is HP1a. This protein has two main domains, namely the chromoshadow and the chromodomain, separated by a hinge region. Over the years, several works have taken on the task of identifying HP1a partners using different strategies. In this review, we focus on describing these interactions and the possible complexes and subcomplexes associated with this critical protein. Characterization of these complexes will help us to clearly understand the implications of the interactions of HP1a in heterochromatin maintenance, heterochromatin dynamics, and heterochromatin's direct relationship to gene regulation and chromatin organization.
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Affiliation(s)
| | | | | | - Viviana Valadez-Graham
- Instituto de Biotecnología, Departamento de Genética del Desarrollo y Fisiología Molecular, Universidad Nacional Autónoma de México, Cuernavaca Morelos 62210, Mexico; (S.M.-N.); (V.E.N.-C.); (M.Z.)
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16
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Meyer-Nava S, Torres A, Zurita M, Valadez-Graham V. Molecular effects of dADD1 misexpression in chromatin organization and transcription. BMC Mol Cell Biol 2020; 21:17. [PMID: 32293240 PMCID: PMC7092677 DOI: 10.1186/s12860-020-00257-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Accepted: 03/04/2020] [Indexed: 12/14/2022] Open
Abstract
Background dADD1 and dXNP proteins are the orthologs in Drosophila melanogaster of the ADD and SNF2 domains, respectively, of the ATRX vertebrate’s chromatin remodeler, they suppress position effect variegation phenotypes and participate in heterochromatin maintenance. Results We performed a search in human cancer databases and found that ATRX protein levels were elevated in more than 4.4% of the samples analyzed. Using the Drosophila model, we addressed the effects of over and under-expression of dADD1 proteins in polytene cells. Elevated levels of dADD1 in fly tissues caused different phenotypes, such as chromocenter disruption and loss of banding pattern at the chromosome arms. Analyses of the heterochromatin maintenance protein HP1a, the dXNP ATPase and the histone post-translational modification H3K9me3 revealed changes in their chromatin localization accompanied by mild transcriptional defects of genes embedded in heterochromatic regions. Furthermore, the expression of heterochromatin embedded genes in null dadd1 organisms is lower than in the wild-type conditions. Conclusion These data indicate that dADD1 overexpression induces chromatin changes, probably affecting the stoichiometry of HP1a containing complexes that lead to transcriptional and architectural changes. Our results place dADD1 proteins as important players in the maintenance of chromatin architecture and heterochromatic gene expression.
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Affiliation(s)
- Silvia Meyer-Nava
- Instituto de Biotecnología. Universidad Nacional Autónoma de México, Campus Morelos, Av. Universidad 2001, C.P, 62210, Cuernavaca, Morelos, Mexico
| | - Amada Torres
- Instituto de Biotecnología. Universidad Nacional Autónoma de México, Campus Morelos, Av. Universidad 2001, C.P, 62210, Cuernavaca, Morelos, Mexico
| | - Mario Zurita
- Instituto de Biotecnología. Universidad Nacional Autónoma de México, Campus Morelos, Av. Universidad 2001, C.P, 62210, Cuernavaca, Morelos, Mexico
| | - Viviana Valadez-Graham
- Instituto de Biotecnología. Universidad Nacional Autónoma de México, Campus Morelos, Av. Universidad 2001, C.P, 62210, Cuernavaca, Morelos, Mexico.
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17
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Seller CA, Cho CY, O'Farrell PH. Rapid embryonic cell cycles defer the establishment of heterochromatin by Eggless/SetDB1 in Drosophila. Genes Dev 2019; 33:403-417. [PMID: 30808658 PMCID: PMC6446540 DOI: 10.1101/gad.321646.118] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Accepted: 01/14/2019] [Indexed: 12/15/2022]
Abstract
Acquisition of chromatin modifications during embryogenesis distinguishes different regions of an initially naïve genome. In many organisms, repetitive DNA is packaged into constitutive heterochromatin that is marked by di/trimethylation of histone H3K9 and the associated protein HP1a. These modifications enforce the unique epigenetic properties of heterochromatin. However, in the early Drosophila melanogaster embryo, the heterochromatin lacks these modifications, which appear only later, when rapid embryonic cell cycles slow down at the midblastula transition (MBT). Here we focus on the initial steps restoring heterochromatic modifications in the embryo. We describe the JabbaTrap, a technique for inactivating maternally provided proteins in embryos. Using the JabbaTrap, we reveal a major requirement for the methyltransferase Eggless/SetDB1 in the establishment of heterochromatin. In contrast, other methyltransferases contribute minimally. Live imaging reveals that endogenous Eggless gradually accumulates on chromatin in interphase but then dissociates in mitosis, and its accumulation must restart in the next cell cycle. Cell cycle slowing as the embryo approaches the MBT permits increasing accumulation and action of Eggless at its targets. Experimental manipulation of interphase duration shows that cell cycle speed regulates Eggless. We propose that developmental slowing of the cell cycle times embryonic heterochromatin formation.
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Affiliation(s)
- Charles A Seller
- Department of Biochemistry and Biophysics, University of California at San Francisco, San Francisco, California 94143, USA
| | - Chun-Yi Cho
- Department of Biochemistry and Biophysics, University of California at San Francisco, San Francisco, California 94143, USA
| | - Patrick H O'Farrell
- Department of Biochemistry and Biophysics, University of California at San Francisco, San Francisco, California 94143, USA
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18
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Leatham-Jensen M, Uyehara CM, Strahl BD, Matera AG, Duronio RJ, McKay DJ. Lysine 27 of replication-independent histone H3.3 is required for Polycomb target gene silencing but not for gene activation. PLoS Genet 2019; 15:e1007932. [PMID: 30699116 PMCID: PMC6370247 DOI: 10.1371/journal.pgen.1007932] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Revised: 02/11/2019] [Accepted: 01/03/2019] [Indexed: 12/23/2022] Open
Abstract
Proper determination of cell fates depends on epigenetic information that is used to preserve memory of decisions made earlier in development. Post-translational modification of histone residues is thought to be a central means by which epigenetic information is propagated. In particular, modifications of histone H3 lysine 27 (H3K27) are strongly correlated with both gene activation and gene repression. H3K27 acetylation is found at sites of active transcription, whereas H3K27 methylation is found at loci silenced by Polycomb group proteins. The histones bearing these modifications are encoded by the replication-dependent H3 genes as well as the replication-independent H3.3 genes. Owing to differential rates of nucleosome turnover, H3K27 acetylation is enriched on replication-independent H3.3 histones at active gene loci, and H3K27 methylation is enriched on replication-dependent H3 histones across silenced gene loci. Previously, we found that modification of replication-dependent H3K27 is required for Polycomb target gene silencing, but it is not required for gene activation. However, the contribution of replication-independent H3.3K27 to these functions is unknown. Here, we used CRISPR/Cas9 to mutate the endogenous replication-independent H3.3K27 to a non-modifiable residue. Surprisingly, we find that H3.3K27 is also required for Polycomb target gene silencing despite the association of H3.3 with active transcription. However, the requirement for H3.3K27 comes at a later stage of development than that found for replication-dependent H3K27, suggesting a greater reliance on replication-independent H3.3K27 in post-mitotic cells. Notably, we find no evidence of global transcriptional defects in H3.3K27 mutants, despite the strong correlation between H3.3K27 acetylation and active transcription. During development, naïve precursor cells acquire distinct identities through differential regulation of gene expression. The process of cell fate specification is progressive and depends on memory of prior developmental decisions. Maintaining cell identities over time is not dependent on changes in genome sequence. Instead, epigenetic mechanisms propagate information on cell identity by maintaining select sets of genes in either the on or off state. Chemical modifications of histone proteins, which package and organize the genome within cells, are thought to play a central role in epigenetic gene regulation. However, identifying which histone modifications are required for gene regulation, and defining the mechanisms through which they function in the maintenance of cell identity, remains a longstanding research challenge. Here, we focus on the role of histone H3 lysine 27 (H3K27). Modifications of H3K27 are associated with both gene activation and gene silencing (i.e. H3K27 acetylation and methylation, respectively). The histones bearing these modifications are encoded by different histone genes. One set of histone genes is only expressed during cell division, whereas the other set of histone genes is expressed in both dividing and non-dividing cells. Because most cells permanently stop dividing by the end of development, these “replication-independent” histone genes are potentially important for long-term maintenance of cell identity. In this study, we demonstrate that replication-independent H3K27 is required for gene silencing by the Polycomb group of epigenetic regulators. However, despite a strong correlation between replication-independent histones and active genes, we find that replication-independent H3K27 is not required for gene activation. As mutations in replication-independent H3K27 have recently been identified in human cancers, this work may help to inform the mechanisms by which histone mutations contribute to human disease.
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Affiliation(s)
- Mary Leatham-Jensen
- Department of Biology, The University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America
- Department of Genetics, The University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America
- Integrative Program for Biological and Genome Sciences, The University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America
| | - Christopher M. Uyehara
- Department of Biology, The University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America
- Department of Genetics, The University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America
- Integrative Program for Biological and Genome Sciences, The University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America
- Curriculum in Genetics and Molecular Biology, The University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America
| | - Brian D. Strahl
- Department of Biochemistry and Biophysics, The University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America
- Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America
| | - A. Gregory Matera
- Department of Biology, The University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America
- Department of Genetics, The University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America
- Integrative Program for Biological and Genome Sciences, The University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America
- Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America
| | - Robert J. Duronio
- Department of Biology, The University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America
- Department of Genetics, The University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America
- Integrative Program for Biological and Genome Sciences, The University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America
- Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America
| | - Daniel J. McKay
- Department of Biology, The University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America
- Department of Genetics, The University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America
- Integrative Program for Biological and Genome Sciences, The University of North Carolina at Chapel Hill, Chapel Hill, NC, United States of America
- * E-mail:
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19
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H3K9 Promotes Under-Replication of Pericentromeric Heterochromatin in Drosophila Salivary Gland Polytene Chromosomes. Genes (Basel) 2019; 10:genes10020093. [PMID: 30700014 PMCID: PMC6409945 DOI: 10.3390/genes10020093] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Revised: 01/24/2019] [Accepted: 01/25/2019] [Indexed: 12/11/2022] Open
Abstract
Chromatin structure and its organization contributes to the proper regulation and timing of DNA replication. Yet, the precise mechanism by which chromatin contributes to DNA replication remains incompletely understood. This is particularly true for cell types that rely on polyploidization as a developmental strategy for growth and high biosynthetic capacity. During Drosophila larval development, cells of the salivary gland undergo endoreplication, repetitive rounds of DNA synthesis without intervening cell division, resulting in ploidy values of ~1350C. S phase of these endocycles displays a reproducible pattern of early and late replicating regions of the genome resulting from the activity of the same replication initiation factors that are used in diploid cells. However, unlike diploid cells, the latest replicating regions of polyploid salivary gland genomes, composed primarily of pericentric heterochromatic enriched in H3K9 methylation, are not replicated each endocycle, resulting in under-replicated domains with reduced ploidy. Here, we employ a histone gene replacement strategy in Drosophila to demonstrate that mutation of a histone residue important for heterochromatin organization and function (H3K9) but not mutation of a histone residue important for euchromatin function (H4K16), disrupts proper endoreplication in Drosophila salivary gland polyploid genomes thereby leading to DNA copy gain in pericentric heterochromatin. These findings reveal that H3K9 is necessary for normal levels of under-replication of pericentric heterochromatin and suggest that under-replication at pericentric heterochromatin is mediated through H3K9 methylation.
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20
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Sex-specific phenotypes of histone H4 point mutants establish dosage compensation as the critical function of H4K16 acetylation in Drosophila. Proc Natl Acad Sci U S A 2018; 115:13336-13341. [PMID: 30530664 PMCID: PMC6310812 DOI: 10.1073/pnas.1817274115] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
The posttranslational modification of nucleosomes is implicated in the regulation of gene expression and chromatin packaging in all eukaryotes. In this study, we investigate the function of histone H4 lysine 16 (H4K16) and its acetylation in Drosophila by generating strains in which lysine 16 is mutated to arginine, glutamine, or alanine. The main conclusion of our paper is that even though H4K16 acetylation was reported to be a critical regulator of chromatin folding in vitro and has therefore been assumed to affect many different nuclear processes, its essential function in Drosophila is in one process: X-chromosome dosage compensation in males. Acetylation of histone H4 at lysine 16 (H4K16) modulates nucleosome–nucleosome interactions and directly affects nucleosome binding by certain proteins. In Drosophila, H4K16 acetylation by the dosage compensation complex subunit Mof is linked to increased transcription of genes on the single X chromosome in males. Here, we analyzed Drosophila containing different H4K16 mutations or lacking Mof protein. An H4K16A mutation causes embryonic lethality in both sexes, whereas an H4K16R mutation permits females to develop into adults but causes lethality in males. The acetyl-mimic mutation H4K16Q permits both females and males to develop into adults. Complementary analyses reveal that males lacking maternally deposited and zygotically expressed Mof protein arrest development during gastrulation, whereas females of the same genotype develop into adults. Together, this demonstrates the causative role of H4K16 acetylation by Mof for dosage compensation in Drosophila and uncovers a previously unrecognized requirement for this process already during the onset of zygotic gene transcription.
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21
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Meers MP, Leatham-Jensen M, Penke TJR, McKay DJ, Duronio RJ, Matera AG. An Animal Model for Genetic Analysis of Multi-Gene Families: Cloning and Transgenesis of Large Tandemly Repeated Histone Gene Clusters. Methods Mol Biol 2018; 1832:309-325. [PMID: 30073535 DOI: 10.1007/978-1-4939-8663-7_17] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Histone post-translational modifications (PTMs) are thought to participate in a range of essential molecular and cellular processes, including gene expression, replication, and nuclear organization. Importantly, histone PTMs are also thought to be prime candidates for carriers of epigenetic information across cell cycles and generations. However, directly testing the necessity of histone PTMs themselves in these processes by mutagenesis has been extremely difficult to carry out because of the highly repetitive nature of histone genes in animal genomes. We developed a transgenic system to generate Drosophila melanogaster genotypes in which the entire complement of replication-dependent histone genes is mutant at a residue of interest. We built a BAC vector containing a visible marker for lineage tracking along with the capacity to clone large (60-100 kb) inserts that subsequently can be site-specifically integrated into the D. melanogaster genome. We demonstrate that artificial tandem arrays of the core 5 kb replication-dependent histone repeat can be generated with relative ease. This genetic platform represents the first histone replacement system to leverage a single tandem transgenic insertion for facile genetics and analysis of molecular and cellular phenotypes. We demonstrate the utility of our system for directly preventing histone residues from being modified, and studying the consequent phenotypes. This system can be generalized to the cloning and transgenic insertion of any tandemly repeated sequence of biological interest.
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Affiliation(s)
- Michael P Meers
- Integrative Program in Biological and Genome Sciences, Curriculum in Genetics and Molecular Biology, Department of Biology, Department of Genetics, Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, USA
| | - Mary Leatham-Jensen
- Integrative Program in Biological and Genome Sciences, Curriculum in Genetics and Molecular Biology, Department of Biology, Department of Genetics, Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, USA
| | - Taylor J R Penke
- Integrative Program in Biological and Genome Sciences, Curriculum in Genetics and Molecular Biology, Department of Biology, Department of Genetics, Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, USA
| | - Daniel J McKay
- Integrative Program in Biological and Genome Sciences, Curriculum in Genetics and Molecular Biology, Department of Biology, Department of Genetics, Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, USA
| | - Robert J Duronio
- Integrative Program in Biological and Genome Sciences, Curriculum in Genetics and Molecular Biology, Department of Biology, Department of Genetics, Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, USA
| | - A Gregory Matera
- Integrative Program in Biological and Genome Sciences, Curriculum in Genetics and Molecular Biology, Department of Biology, Department of Genetics, Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, USA.
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