1
|
Grabowska A, Sas-Nowosielska H, Wojtas B, Holm-Kaczmarek D, Januszewicz E, Yushkevich Y, Czaban I, Trzaskoma P, Krawczyk K, Gielniewski B, Martin-Gonzalez A, Filipkowski RK, Olszynski KH, Bernas T, Szczepankiewicz AA, Sliwinska MA, Kanhema T, Bramham CR, Bokota G, Plewczynski D, Wilczynski GM, Magalska A. Activation-induced chromatin reorganization in neurons depends on HDAC1 activity. Cell Rep 2022; 38:110352. [PMID: 35172152 DOI: 10.1016/j.celrep.2022.110352] [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: 02/09/2021] [Revised: 11/09/2021] [Accepted: 01/19/2022] [Indexed: 11/23/2022] Open
Abstract
Spatial chromatin organization is crucial for transcriptional regulation and might be particularly important in neurons since they dramatically change their transcriptome in response to external stimuli. We show that stimulation of neurons causes condensation of large chromatin domains. This phenomenon can be observed in vitro in cultured rat hippocampal neurons as well as in vivo in the amygdala and hippocampal neurons. Activity-induced chromatin condensation is an active, rapid, energy-dependent, and reversible process. It involves calcium-dependent pathways but is independent of active transcription. It is accompanied by the redistribution of posttranslational histone modifications and rearrangements in the spatial organization of chromosome territories. Moreover, it leads to the reorganization of nuclear speckles and active domains located in their proximity. Finally, we find that the histone deacetylase HDAC1 is the key regulator of this process. Our results suggest that HDAC1-dependent chromatin reorganization constitutes an important level of transcriptional regulation in neurons.
Collapse
Affiliation(s)
- Agnieszka Grabowska
- Laboratory of Molecular Basis of Cell Motility, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 02-093 Warsaw, Poland
| | - Hanna Sas-Nowosielska
- Laboratory of Molecular Basis of Cell Motility, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 02-093 Warsaw, Poland
| | - Bartosz Wojtas
- Laboratory of Sequencing, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 02-093 Warsaw, Poland
| | - Dagmara Holm-Kaczmarek
- Laboratory of Molecular Basis of Cell Motility, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 02-093 Warsaw, Poland
| | - Elzbieta Januszewicz
- Laboratory of Molecular and Systemic Neuromorphology, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 02-093 Warsaw, Poland
| | - Yana Yushkevich
- Laboratory of Molecular Basis of Cell Motility, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 02-093 Warsaw, Poland
| | - Iwona Czaban
- Laboratory of Molecular and Systemic Neuromorphology, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 02-093 Warsaw, Poland
| | - Pawel Trzaskoma
- Laboratory of Molecular and Systemic Neuromorphology, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 02-093 Warsaw, Poland
| | - Katarzyna Krawczyk
- Laboratory of Molecular and Systemic Neuromorphology, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 02-093 Warsaw, Poland
| | - Bartlomiej Gielniewski
- Laboratory of Sequencing, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 02-093 Warsaw, Poland
| | - Ana Martin-Gonzalez
- Laboratory of Molecular and Systemic Neuromorphology, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 02-093 Warsaw, Poland; Instituto de Neurociencias, Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas, San Juan de Alicante, 03550 Alicante, Spain
| | - Robert Kuba Filipkowski
- Behavior and Metabolism Research Laboratory, Mossakowski Medical Research Institute, Polish Academy of Sciences, 02-106 Warsaw, Poland
| | - Krzysztof Hubert Olszynski
- Behavior and Metabolism Research Laboratory, Mossakowski Medical Research Institute, Polish Academy of Sciences, 02-106 Warsaw, Poland
| | - Tytus Bernas
- Laboratory of Imaging Tissue Structure and Function, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 02-093 Warsaw, Poland; Department of Anatomy and Neurology, VCU School of Medicine, Richmond, VA 23284, USA
| | - Andrzej Antoni Szczepankiewicz
- Laboratory of Molecular and Systemic Neuromorphology, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 02-093 Warsaw, Poland
| | - Malgorzata Alicja Sliwinska
- Laboratory of Imaging Tissue Structure and Function, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 02-093 Warsaw, Poland
| | - Tambudzai Kanhema
- Department of Biomedicine, University of Bergen, 5020 Bergen, Norway; KG Jebsen Centre for Neuropsychiatric Disorders, University of Bergen, 5020 Bergen, Norway
| | - Clive R Bramham
- Department of Biomedicine, University of Bergen, 5020 Bergen, Norway; KG Jebsen Centre for Neuropsychiatric Disorders, University of Bergen, 5020 Bergen, Norway
| | - Grzegorz Bokota
- Centre of New Technologies, University of Warsaw, 02-097 Warsaw, Poland; Institute of Informatics, University of Warsaw, 02-097 Warsaw, Poland
| | - Dariusz Plewczynski
- Centre of New Technologies, University of Warsaw, 02-097 Warsaw, Poland; Faculty of Mathematics and Information Science, Warsaw University of Technology, 00-662 Warsaw, Poland
| | - Grzegorz Marek Wilczynski
- Laboratory of Molecular and Systemic Neuromorphology, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 02-093 Warsaw, Poland
| | - Adriana Magalska
- Laboratory of Molecular Basis of Cell Motility, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 02-093 Warsaw, Poland.
| |
Collapse
|
2
|
Wahab S, Saettone A, Nabeel-Shah S, Dannah N, Fillingham J. Exploring the Histone Acetylation Cycle in the Protozoan Model Tetrahymena thermophila. Front Cell Dev Biol 2020; 8:509. [PMID: 32695779 PMCID: PMC7339932 DOI: 10.3389/fcell.2020.00509] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Accepted: 05/28/2020] [Indexed: 12/22/2022] Open
Abstract
The eukaryotic histone acetylation cycle is composed of three classes of proteins, histone acetyltransferases (HATs) that add acetyl groups to lysine amino acids, bromodomain (BRD) containing proteins that are one of the most characterized of several protein domains that recognize acetyl-lysine (Kac) and effect downstream function, and histone deacetylases (HDACs) that catalyze the reverse reaction. Dysfunction of selected proteins of these three classes is associated with human disease such as cancer. Additionally, the HATs, BRDs, and HDACs of fungi and parasitic protozoa present potential drug targets. Despite their importance, the function and mechanisms of HATs, BRDs, and HDACs and how they relate to chromatin remodeling (CR) remain incompletely understood. Tetrahymena thermophila (Tt) provides a highly tractable single-celled free-living protozoan model for studying histone acetylation, featuring a massively acetylated somatic genome, a property that was exploited in the identification of the first nuclear/type A HAT Gcn5 in the 1990s. Since then, Tetrahymena remains an under-explored model for the molecular analysis of HATs, BRDs, and HDACs. Studies of HATs, BRDs, and HDACs in Tetrahymena have the potential to reveal the function of HATs and BRDs relevant to both fundamental eukaryotic biology and to the study of disease mechanisms in parasitic protozoa.
Collapse
Affiliation(s)
| | | | | | | | - Jeffrey Fillingham
- Department of Chemistry and Biology, Ryerson University, Toronto, ON, Canada
| |
Collapse
|
3
|
Garg J, Saettone A, Nabeel-Shah S, Cadorin M, Ponce M, Marquez S, Pu S, Greenblatt J, Lambert JP, Pearlman RE, Fillingham J. The Med31 Conserved Component of the Divergent Mediator Complex in Tetrahymena thermophila Participates in Developmental Regulation. Curr Biol 2019; 29:2371-2379.e6. [PMID: 31280994 DOI: 10.1016/j.cub.2019.06.052] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Revised: 05/18/2019] [Accepted: 06/18/2019] [Indexed: 11/24/2022]
Abstract
Mediator is a large protein complex required for basal and regulated expression of most RNA polymerase II (RNAP II)-transcribed genes, in part due to its interaction with and phosphorylation of the conserved C-terminal domain (CTD) of Rpb1 [1, 2]. Mediator has been implicated in many aspects of gene expression including chromatin looping [3], higher-order chromatin folding [4], mRNA processing [5] and export [6], and transcriptional memory [7]. Mediator is thought to have played a major role during eukaryotic diversification [8, 9], although its function remains unknown in evolutionarily deep branching eukaryotes lacking canonical CTD heptad repeats. We used the ciliate protozoan Tetrahymena thermophila as a model organism whose genome encodes a highly divergent Rpb1 lacking canonical CTD heptad repeats. We endogenously tagged the Med31 subunit of the Mediator complex and performed affinity purification coupled with mass spectrometry (AP-MS) to identify Mediator subunits. We found that Med31 physically interacts with a large number of proteins (>20), several of which share similarities to canonical Mediator subunits in yeast and humans as well as Tetrahymena-specific proteins. Furthermore, Med31 ChIP-seq analysis suggested a global role for Mediator in transcription regulation. We demonstrated that MED31 knockdown in growing Tetrahymena results in the ectopic expression of developmental genes important for programmed DNA rearrangements. In addition, indirect immunofluorescence revealed Med31 localization in meiotic micronuclei, implicating Mediator in RNAPII-dependent ncRNA transcription. Our results reveal structural and functional insights and implicate Mediator as an ancient cellular machinery for transcription regulation with a possible involvement in global transcription of ncRNAs.
Collapse
Affiliation(s)
- Jyoti Garg
- Department of Biology, York University, 4700 Keele Street, Toronto, ON M3J 1P3, Canada
| | - Alejandro Saettone
- Department of Chemistry and Biology, Ryerson University, 350 Victoria Street, Toronto, ON M5B 2K3, Canada
| | - Syed Nabeel-Shah
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada; Donnelly Centre, University of Toronto, Toronto, ON M5S 3E1, Canada
| | - Matthew Cadorin
- Department of Chemistry and Biology, Ryerson University, 350 Victoria Street, Toronto, ON M5B 2K3, Canada
| | - Marcelo Ponce
- SciNet HPC Consortium, University of Toronto, 661 University Avenue, Suite 1140, Toronto, ON M5G 1M1, Canada
| | - Susanna Marquez
- Department of Biology, York University, 4700 Keele Street, Toronto, ON M3J 1P3, Canada
| | - Shuye Pu
- Donnelly Centre, University of Toronto, Toronto, ON M5S 3E1, Canada
| | - Jack Greenblatt
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1A8, Canada; Donnelly Centre, University of Toronto, Toronto, ON M5S 3E1, Canada
| | - Jean-Philippe Lambert
- Department of Molecular Medicine and Cancer Research Centre, Université Laval, Quebec, QC, Canada; CHU de Québec Research Center, CHUL, 2705 Laurier Boulevard, Quebec, QC G1V 4G2, Canada
| | - Ronald E Pearlman
- Department of Biology, York University, 4700 Keele Street, Toronto, ON M3J 1P3, Canada
| | - Jeffrey Fillingham
- Department of Chemistry and Biology, Ryerson University, 350 Victoria Street, Toronto, ON M5B 2K3, Canada.
| |
Collapse
|
4
|
Adipocyte Metabolic Pathways Regulated by Diet Control the Female Germline Stem Cell Lineage in Drosophila melanogaster. Genetics 2017; 206:953-971. [PMID: 28396508 DOI: 10.1534/genetics.117.201921] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Accepted: 04/05/2017] [Indexed: 12/29/2022] Open
Abstract
Nutrients affect adult stem cells through complex mechanisms involving multiple organs. Adipocytes are highly sensitive to diet and have key metabolic roles, and obesity increases the risk for many cancers. How diet-regulated adipocyte metabolic pathways influence normal stem cell lineages, however, remains unclear. Drosophila melanogaster has highly conserved adipocyte metabolism and a well-characterized female germline stem cell (GSC) lineage response to diet. Here, we conducted an isobaric tags for relative and absolute quantification (iTRAQ) proteomic analysis to identify diet-regulated adipocyte metabolic pathways that control the female GSC lineage. On a rich (relative to poor) diet, adipocyte Hexokinase-C and metabolic enzymes involved in pyruvate/acetyl-CoA production are upregulated, promoting a shift of glucose metabolism toward macromolecule biosynthesis. Adipocyte-specific knockdown shows that these enzymes support early GSC progeny survival. Further, enzymes catalyzing fatty acid oxidation and phosphatidylethanolamine synthesis in adipocytes promote GSC maintenance, whereas lipid and iron transport from adipocytes controls vitellogenesis and GSC number, respectively. These results show a functional relationship between specific metabolic pathways in adipocytes and distinct processes in the GSC lineage, suggesting the adipocyte metabolism-stem cell link as an important area of investigation in other stem cell systems.
Collapse
|
5
|
Genetic analysis of common variants in the HDAC2 gene with schizophrenia susceptibility in Han Chinese. J Hum Genet 2015; 60:479-84. [DOI: 10.1038/jhg.2015.66] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2015] [Revised: 05/01/2015] [Accepted: 05/03/2015] [Indexed: 12/17/2022]
|
6
|
Zhang C, Gao S, Molascon AJ, Wang Z, Gorovsky MA, Liu Y, Andrews PC. Bioinformatic and proteomic analysis of bulk histones reveals PTM crosstalk and chromatin features. J Proteome Res 2014; 13:3330-7. [PMID: 24894457 PMCID: PMC4096215 DOI: 10.1021/pr5001829] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
![]()
Systems
analysis of chromatin has been constrained by complex patterns
and dynamics of histone post-translational modifications (PTMs), which
represent major challenges for both mass spectrometry (MS) and immuno-based
approaches (e.g., chromatin immuno-precipitation, ChIP). Here we present
a proof-of-concept study demonstrating that crosstalk among PTMs and
their functional significance can be revealed via systematic bioinformatic
and proteomic analysis of steady-state histone PTM levels from cells
under various perturbations. Using high resolution tandem MS, we quantified
53 modification states from all core histones and their conserved
variants in the unicellular eukaryotic model organism Tetrahymena. By correlating histone PTM patterns across 15 different conditions,
including various physiological states and mutations of key histone
modifying enzymes, we identified 5 specific chromatin states with
characteristic covarying histone PTMs and associated them with distinctive
functions in replication, transcription, and DNA repair. In addition
to providing a detailed picture on histone PTM crosstalk at global
levels, this work has established a novel bioinformatic and proteomic
approach, which can be adapted to other organisms and readily scaled
up to allow increased resolution of chromatin states.
Collapse
Affiliation(s)
- Chunchao Zhang
- Departments of †Computational Medicine and Bioinformatics, ‡Pathology, ∥Chemistry, and ⊥Biological Chemistry, University of Michigan , Ann Arbor, Michigan 48109, United States
| | | | | | | | | | | | | |
Collapse
|
7
|
Han H, Yu Y, Shi J, Yao Y, Li W, Kong N, Wu Y, Wang C, Wang S, Meng X, Kou C. Associations of histone deacetylase-2 and histone deacetylase-3 genes with schizophrenia in a Chinese population. Asia Pac Psychiatry 2013; 5:11-6. [PMID: 23857786 DOI: 10.1111/j.1758-5872.2012.00205.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2011] [Accepted: 04/03/2012] [Indexed: 12/14/2022]
Abstract
INTRODUCTION To explore the association between histone deacetylase-2 (HDAC2) and histone deacetylase-3 (HDAC3) gene polymorphisms and schizophrenia. METHODS A total of 208 family trios consisting of fathers, mothers and affected offspring with schizophrenia were recruited as our subjects. Four tag SNPs on HDAC2 (rs10499080, rs6568819, rs2499618 and rs13204445) and two tag SNPs on HDAC3 (rs11741808, rs2530223) genes were selected. The Mass ARRAY Assay Design software (Sequenom) was used to design amplification and allele specific extension primers. The Hardy-Weinberg equilibrium (HWE) for genotypic distributions was tested using the chi-square goodness-of-fit test. Allelic association for a single tag SNP was analyzed by using family-based association tests including the haplotype-based haplotype relative risk (HHRR) test and the transmission disequilibrium test (TDT). RESULTS The genotypic distributions of HDAC2 SNPs rs6568819, rs2499618 and rs13204445 and HDAC3 SNPs rs11741808 and rs2530223 were all in Hardy-Weinberg equilibrium (P > 0.05). HHRR analysis revealed no associations between the SNPs and schizophrenia (P > 0.05). In addition, the TDT did not show any significant associations between HDAC2 and HDAC3 SNPs and schizophrenia (P > 0.05). DISCUSSION HDAC2 and HDAC3 might not be associated with schizophrenia in the Chinese population.
Collapse
Affiliation(s)
- Hongzhi Han
- Department of Epidemiology and Biostatistics, School of Public Health, Jilin University, Changchun, China
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
8
|
Chaudhary N, Nakka KK, Maulik N, Chattopadhyay S. Epigenetic manifestation of metabolic syndrome and dietary management. Antioxid Redox Signal 2012; 17:254-81. [PMID: 22229755 DOI: 10.1089/ars.2011.4387] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
SIGNIFICANCE Metabolic syndrome constitutes a group of disorders such as insulin resistance, hypertension, and hypertriglyceridemia, predisposing an individual to risk factors such as cardiovascular disease, diabetes, obesity, and dyslipidemia. A majority of these diseases are influenced by the environmental factors, nutrient uptake, and genetic profile of an individual that together dysregulate gene function. These genetic and nongenetic factors are reported to introduce epigenetic cues that modulate the gene function which is inherited by the offspring. RECENT ADVANCES Considering the epigenetic modulation of the metabolic disorders, nutrigenomics has been distinctly categorized as a branch that deals with modulatory effect of nutrients on metabolic disorders and disease progression by supplementing the individuals with key nutrient-enriched diets which are derived from plant and animal sources. CRITICAL ISSUES Nutritional components of the diet regulate the metabolic health of an individual either by controlling the expression of some key genes related to metabolic pathways or by modulating the epigenetic events on such genes. The present article discusses various metabolic disorders in detail and the effect of nutrients on the specific genes causing those disorders. We also highlight the molecular mechanisms of some metabolic disorders through epigenetic modifications and possible therapeutic interventions. FUTURE DIRECTIONS With the advent of high-throughput technologies and epigenetic modulation of the metabolic disorders, an altered epigenetic code that is programmed due to improper nutrients can be reverted back by supplementing the diet with various plant-derived compounds. The implication of small molecular drugs is also of utmost significance for challenging the metabolic disorders.
Collapse
Affiliation(s)
- Nidhi Chaudhary
- Department of Chromatin and Disease, National Centre for Cell Science, Pune, India
| | | | | | | |
Collapse
|
9
|
Park JA, Kim AJ, Kang Y, Jung YJ, Kim HK, Kim KC. Deacetylation and methylation at histone H3 lysine 9 (H3K9) coordinate chromosome condensation during cell cycle progression. Mol Cells 2011; 31:343-9. [PMID: 21359677 PMCID: PMC3933963 DOI: 10.1007/s10059-011-0044-4] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2010] [Revised: 01/04/2011] [Accepted: 01/13/2011] [Indexed: 01/26/2023] Open
Abstract
Interphasic chromatin condenses into the chromosomes in order to facilitate the correct segregation of genetic information. It has been previously reported that the phosphorylation and methylation of the N-terminal tail of histone H3 are responsible for chromosome condensation. In this study, we demonstrate that the deacetylation and methylation of histone H3 lysine 9 (H3K9) are required for proper chromosome condensation. We confirmed that H3K9ac levels were reduced, whereas H3K9me3 levels were increased in mitotic cells, via immunofluorescence and Western blot analysis. Nocodazole treatment induced G2/M arrest but co-treatment with TSA, an HDAC inhibitor, delayed cell cycle progression. However, the HMTase inhibitor, AdoX, had no effect on nocodazole-induced G2/M arrest, thereby indicating that sequential modifications of H3K9 are required for proper chromosome condensation. The expression of SUV39H1 and SETDB1, H3K9me3-responsible HMTases, are specifically increased along with H3K9me3 in nocodazole-arrested buoyant cells, which suggests that the increased expression of those proteins is an important step in chromosome condensation. H3K9me3 was highly concentrated in the vertical chromosomal axis during prophase and prometaphase. Collectively, the results of this study indicate that sequential modifications at H3K9 are associated with correct chromosome condensation, and that H3K9me3 may be relevant to the condensation of chromosome length.
Collapse
Affiliation(s)
- Jin-Ah Park
- Medical and Bio-Material Research Center and Department of Biology, College of Natural Sciences, Kangwon National University, Chuncheon 200-701, Korea
| | - Ae-Jin Kim
- Medical and Bio-Material Research Center and Department of Biology, College of Natural Sciences, Kangwon National University, Chuncheon 200-701, Korea
| | - Yoonsung Kang
- DNA Repair Research Center and Department of Bio-Materials, Chosun University, Gwangju 501-759, Korea
| | - Yu-Jin Jung
- Medical and Bio-Material Research Center and Department of Biology, College of Natural Sciences, Kangwon National University, Chuncheon 200-701, Korea
| | - Hyong Kyu Kim
- College of Medicine, Chungbuk National University, Cheongju 361-763, Korea
| | - Keun-Cheol Kim
- Medical and Bio-Material Research Center and Department of Biology, College of Natural Sciences, Kangwon National University, Chuncheon 200-701, Korea
| |
Collapse
|
10
|
A class II histone deacetylase acts on newly synthesized histones in Tetrahymena. EUKARYOTIC CELL 2008; 7:471-82. [PMID: 18178773 DOI: 10.1128/ec.00409-07] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Newly synthesized histones are acetylated prior to their deposition into nucleosomes. Following nucleosome formation and positioning, they are rapidly deacetylated, an event that coincides with further maturation of the chromatin fiber. The histone deacetylases (HDACs) used for histone deposition and de novo chromatin formation are poorly understood. In the ciliate Tetrahymena thermophila, transcription-related deacetylation in the macronucleus is physically separated from deposition-related deacetylation in the micronucleus. This feature was utilized to identify an HDAC named Thd2, a class II HDAC that acts on newly synthesized histones to remove deposition-related acetyl moieties. The THD2 transcript is alternatively spliced, and the major form contains a putative inositol polyphosphate kinase (IPK) domain similar to Ipk2, an enzyme that promotes chromatin remodeling by SWI/SNF remodeling complexes. Cells lacking Thd2, which retain deposition-related acetyl moieties on new histones, exhibit chromatin and cytological phenotypes indicative of a role for Thd2 in chromatin maturation, including the proteolytic processing of histone H3.
Collapse
|