1
|
Hino M, Tatsuke T, Morio A, Mon H, Lee JM, Masuda A, Kakino K, Tonooka Y, Kusakabe T. Characterization of a Novel Heterochromatin Protein 1 Homolog “HP1c” in the Silkworm, Bombyx mori. Insects 2022; 13:631. [PMID: 35886807 PMCID: PMC9316600 DOI: 10.3390/insects13070631] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 07/09/2022] [Accepted: 07/11/2022] [Indexed: 12/04/2022]
Abstract
Simple Summary Heterochromatin protein 1 (HP1) plays a major role in the formation and maintenance of heterochromatin and in the regulation of gene expression. Five HP1 genes have been found in Drosophila melanogaster and three HP1 genes in Homo sapiens, while in Bombyx mori, two HP1 genes (BmHP1a and BmHP1b) have been reported. In the present study, we analyzed the function of the novel Bombyx mori HP1 gene (BmHP1c), the third HP1 gene in silkworm. BmHP1c has different characteristics from BmHP1a and BmHP1b in terms of transcriptional repression activity, dimer formation, subcellular localization, and effects of RNAi on cell cycle progression. These findings indicate that BmHP1c plays a different role than BmHP1a and BmHP1b. Abstract Heterochromatin protein 1 plays an important role in chromatin structure and gene expression regulation. Three HP1 genes have been found in Homo sapiens, and five HP1 genes have been reported in Drosophila melanogaster. On the other hand, in Bombyx mori, only two HP1 genes, BmHP1a and BmHP1b, were reported. In this research, we have reported the molecular and functional characterization of a novel Bombyx mori HP1 gene (BmHP1c), which had stronger transcriptional repression activity than BmHP1a. BmHP1a and BmHP1b is reported to form homo- and heterodimers, but in co-immunoprecipitation experiments, no homo- or hetero-dimer formation of BmHP1c with the other silkworm HP1s is detected. The intracellular localization of BmHP1c is not only in the nucleus but also in the cytoplasm like mammalian HP1γ. In contrast to human HP1a and b, all three BmHP1s were localized preferentially in the regions poorly stained with DAPI. Interestingly, the double knockdown of BmHP1a and b, but not BmHP1c with a or b, arrested the cell cycle at the G2/M phase. These results suggest that BmHP1c is not essential for cell progression and plays a different role than BmHP1a and BmHP1b.
Collapse
|
2
|
Abstract
In eukaryotes, DNA is packaged into chromatin, which presents significant barriers to transcription. Non-histone chromatin proteins such as the Heterochromatin Protein 1 (HP1) proteins are critical regulators of transcription, contributing to gene regulation through a variety of molecular mechanisms. HP1 proteins are highly conserved, and many eukaryotic genomes contain multiple HP1 genes. Given the presence of multiple HP1 family members within a genome, HP1 proteins can have unique as well as shared functions. Here, we review the mechanisms by which HP1 proteins contribute to the regulation of transcription. Focusing on the Drosophila melanogaster HP1 proteins, we examine the role of these proteins in regulating the transcription of genes, transposable elements, and piRNA clusters. In D. melanogaster, as in other species, HP1 proteins can act as transcriptional repressors and activators. The available data reveal that the precise impact of HP1 proteins on gene expression is highly context dependent, on the specific HP1 protein involved, on its protein partners present, and on the specific chromatin context the interaction occurs in. As a group, HP1 proteins utilize a variety of mechanisms to contribute to transcriptional regulation, including both transcriptional (i.e. chromatin-based) and post-transcriptional (i.e. RNA-based) processes. Despite extensive studies of this important protein family, open questions regarding their functions in gene regulation remain, specifically regarding the role of hetero- versus homodimerization and post-translational modifications of HP1 proteins.
Collapse
Affiliation(s)
- John M Schoelz
- Department of Biology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Nicole C Riddle
- Department of Biology, University of Alabama at Birmingham, Birmingham, AL, USA.
| |
Collapse
|
3
|
Fahham N, Zandi F, Ghahremani MH, Ostad SN, Vaziri B, Shahraeini SS, Sardari S. Unraveling Potential Candidate Targets Associated with Expression of
p16INK4a or p16 Truncated Fragment by Comparative Proteomics Analysis. CURR PROTEOMICS 2022. [DOI: 10.2174/1570164618666210728121529] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Background:
p16 is a tumor suppressor protein that is significantly involved in cycle
regulation through the reduction of cell progression from the G1 phase to the S phase via CDK-cyclin
D/p16INK4a/pRb/E2F cascade. The minimum functional domain of p16 has been uncovered that
may function comparable to wild type p16.
Objective:
To expand the knowledge on molecules and mechanisms by which p16 or p1666-156 fragment
suppresses human fibrosarcoma cell line growth, differential proteome profiles of fibrosarcoma
cells following p16 full length or the functional domain overexpression, were analyzed.
Methods:
Following transfecting HT-1080 fibrosarcoma cells with p16 full length, p1666-156 truncated
form, and pcDNA3.1 empty vector, protein extract of each sample was harvested and clarified
by centrifugation, and then the protein content was determined via Bradford assay. All protein extract
of each sample was analyzed by two-dimensional gel electrophoresis. Immunoblot analysis
was performed as further validation of the expression status of identified proteins.
Results:
Expression of p16 or p1666-156 fragment could induce mostly the common alterations (up/-
down-regulation) of proteome profile of HT-1080 cells. Mass spectrometry identification of the differentially
expressed protein spots revealed several proteins that were grouped in functional clusters,
including cell cycle regulation and proliferation, cell migration and structure, oxidative stress,
protein metabolism, epigenetic regulation, and signal transduction.
Conclusion:
The minimum functional domain of p16 could act in the same way as p16 full length.
Also, these new findings can significantly enrich the understanding of p16 growth-suppressive
function at the molecular level by the introduction of potential candidate targets for new treatment
strategies. Furthermore, the present study provides strong evidence on the functional efficacy of
the identified fragment of p16 for further attempts toward peptidomimetic drug design or gene
transfer to block cancer cell proliferation.
Collapse
Affiliation(s)
- Najmeh Fahham
- Protein Chemistry and Proteomics Laboratory, Biotechnology Research Center, Pasteur Institute of Iran, Tehran,
Iran
| | - Fatemeh Zandi
- Protein Chemistry and Proteomics Laboratory, Biotechnology Research Center, Pasteur Institute of Iran, Tehran,
Iran
| | - Mohammad Hossein Ghahremani
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Tehran University of Medical Sciences,
Tehran, Iran
| | - Seyed Nasser Ostad
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Tehran University of Medical Sciences,
Tehran, Iran
| | - Behrouz Vaziri
- Protein Chemistry and Proteomics Laboratory, Biotechnology Research Center, Pasteur Institute of Iran, Tehran,
Iran
| | - Seyed Sadegh Shahraeini
- Drug Design and Bioinformatics Unit, Department of Medical Biotechnology, Biotechnology Research
Centre, Pasteur Institute of Iran, Tehran, Iran
| | - Soroush Sardari
- Drug Design and Bioinformatics Unit, Department of Medical Biotechnology, Biotechnology Research
Centre, Pasteur Institute of Iran, Tehran, Iran
| |
Collapse
|
4
|
Chang CW, Shen YC, Yan SJ. HP1a-mediated heterochromatin formation inhibits high dietary sugar-induced tumor progression. Cell Death Dis 2021; 12:1130. [PMID: 34866135 DOI: 10.1038/s41419-021-04414-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Revised: 11/08/2021] [Accepted: 11/22/2021] [Indexed: 12/24/2022]
Abstract
High dietary sugar (HDS) is a modern dietary concern that involves excessive consumption of carbohydrates and added sugars, and increases the risk of metabolic disorders and associated cancers. However, epigenetic mechanisms by which HDS induces tumor progression remain unclear. Here, we investigate the role of heterochromatin, an important yet poorly understood part of the epigenome, in HDS-induced tumor progression of Drosophila Ras/Src and Ras/scrib tumor systems. We found that increased heterochromatin formation with overexpression of heterochromatin protein 1a (HP1a), specifically in tumor cells, not only decreases HDS-induced tumor growth/burden but also drastically improves survival of Drosophila with HDS and Ras/Src or Ras/scrib tumors. Moreover, HDS reduces heterochromatin levels in tumor cells. Mechanistically, we demonstrated that increased heterochromatin formation decreases wingless (wg) and Hippo (Hpo) signaling, thereby promoting apoptosis, via inhibition of Yorkie (Yki) nuclear accumulation and upregulation of apoptotic genes, and reduces DNA damage in tumor cells under HDS. Taken together, our work identified a novel epigenetic mechanism by which HP1a-mediated heterochromatin formation suppresses HDS-induced tumor progression likely by decreasing wingless and Hippo signaling, increasing apoptosis, and maintaining genome stability. Our model explains that the molecular, cellular, and organismal aspects of HDS-aggravated tumor progression are dependent on heterochromatin formation, and highlights heterochromatin as a therapeutic target for cancers associated with HDS-induced metabolic disorders.
Collapse
|
5
|
Li CL, Pu M, Wang W, Chaturbedi A, Emerson FJ, Lee SS. Region-specific H3K9me3 gain in aged somatic tissues in Caenorhabditis elegans. PLoS Genet 2021; 17:e1009432. [PMID: 34506495 PMCID: PMC8457455 DOI: 10.1371/journal.pgen.1009432] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 09/22/2021] [Accepted: 08/17/2021] [Indexed: 12/13/2022] Open
Abstract
Epigenetic alterations occur as organisms age, and lead to chromatin deterioration, loss of transcriptional silencing and genomic instability. Dysregulation of the epigenome has been associated with increased susceptibility to age-related disorders. In this study, we aimed to characterize the age-dependent changes of the epigenome and, in turn, to understand epigenetic processes that drive aging phenotypes. We focused on the aging-associated changes in the repressive histone marks H3K9me3 and H3K27me3 in C. elegans. We observed region-specific gain and loss of both histone marks, but the changes are more evident for H3K9me3. We further found alteration of heterochromatic boundaries in aged somatic tissues. Interestingly, we discovered that the most statistically significant changes reflected H3K9me3-marked regions that are formed during aging, and are absent in developing worms, which we termed "aging-specific repressive regions" (ASRRs). These ASRRs preferentially occur in genic regions that are marked by high levels of H3K9me2 and H3K36me2 in larval stages. Maintenance of high H3K9me2 levels in these regions have been shown to correlate with a longer lifespan. Next, we examined whether the changes in repressive histone marks lead to de-silencing of repetitive DNA elements, as reported for several other organisms. We observed increased expression of active repetitive DNA elements but not global re-activation of silent repeats in old worms, likely due to the distributed nature of repetitive elements in the C. elegans genome. Intriguingly, CELE45, a putative short interspersed nuclear element (SINE), was greatly overexpressed at old age and upon heat stress. SINEs have been suggested to regulate transcription in response to various cellular stresses in mammals. It is likely that CELE45 RNAs also play roles in stress response and aging in C. elegans. Taken together, our study revealed significant and specific age-dependent changes in repressive histone modifications and repetitive elements, providing important insights into aging biology.
Collapse
Affiliation(s)
- Cheng-Lin Li
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York, United States of America
| | - Mintie Pu
- State Key Laboratory for Conservation and Utilization of Bio-Resources and Center for Life Science, School of Life Sciences, Yunnan University, Kunming, Yunnan, China
| | - Wenke Wang
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York, United States of America
| | - Amaresh Chaturbedi
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York, United States of America
| | - Felicity J Emerson
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York, United States of America
| | - Siu Sylvia Lee
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York, United States of America
| |
Collapse
|
6
|
Koiwai K, Koyama T, Tsuda S, Toyoda A, Kikuchi K, Suzuki H, Kawano R. Single-cell RNA-seq analysis reveals penaeid shrimp hemocyte subpopulations and cell differentiation process. eLife 2021; 10:e66954. [PMID: 34132195 PMCID: PMC8266392 DOI: 10.7554/elife.66954] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Accepted: 06/15/2021] [Indexed: 01/03/2023] Open
Abstract
Crustacean aquaculture is expected to be a major source of fishery commodities in the near future. Hemocytes are key players of the immune system in shrimps; however, their classification, maturation, and differentiation are still under debate. To date, only discrete and inconsistent information on the classification of shrimp hemocytes has been reported, showing that the morphological characteristics are not sufficient to resolve their actual roles. Our present study using single-cell RNA sequencing revealed six types of hemocytes of Marsupenaeus japonicus based on their transcriptional profiles. We identified markers of each subpopulation and predicted the differentiation pathways involved in their maturation. We also predicted cell growth factors that might play crucial roles in hemocyte differentiation. Different immune roles among these subpopulations were suggested from the analysis of differentially expressed immune-related genes. These results provide a unified classification of shrimp hemocytes, which improves the understanding of its immune system.
Collapse
Affiliation(s)
- Keiichiro Koiwai
- Department of Biotechnology and Life Science, Tokyo University of Agriculture and TechnologyKoganeiJapan
- Laboratory of Genome Science, Tokyo University of Marine Science and TechnologyMinatoJapan
| | - Takashi Koyama
- Fisheries Laboratory, Graduate School of Agricultural and Life Sciences, The University of TokyoHamamatsuJapan
- Graduate School of Fisheries and Environmental Sciences, Nagasaki UniversityNagasakiJapan
| | | | - Atsushi Toyoda
- Advanced Genomics Center, National Institute of GeneticsMishimaJapan
| | - Kiyoshi Kikuchi
- Fisheries Laboratory, Graduate School of Agricultural and Life Sciences, The University of TokyoHamamatsuJapan
| | - Hiroaki Suzuki
- Department of Precision Mechanics, Faculty of Science and Engineering, Chuo UniversityBunkyoJapan
| | - Ryuji Kawano
- Department of Biotechnology and Life Science, Tokyo University of Agriculture and TechnologyKoganeiJapan
| |
Collapse
|
7
|
Casale AM, Cappucci U, Piacentini L. Unravelling HP1 functions: post-transcriptional regulation of stem cell fate. Chromosoma 2021; 130:103-111. [PMID: 34128099 PMCID: PMC8426308 DOI: 10.1007/s00412-021-00760-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Revised: 05/17/2021] [Accepted: 06/01/2021] [Indexed: 12/20/2022]
Abstract
Heterochromatin protein 1 (HP1) is a non-histone chromosomal protein first identified in Drosophila as a major component of constitutive heterochromatin, required for stable epigenetic gene silencing in many species including humans. Over the years, several studies have highlighted additional roles of HP1 in different cellular processes including telomere maintenance, DNA replication and repair, chromosome segregation and, surprisingly, positive regulation of gene expression. In this review, we briefly summarize past research and recent results supporting the unexpected and emerging role of HP1 in activating gene expression. In particular, we discuss the role of HP1 in post-transcriptional regulation of mRNA processing because it has proved decisive in the control of germline stem cells homeostasis in Drosophila and has certainly added a new dimension to our understanding on HP1 targeting and functions in epigenetic regulation of stem cell behaviour.
Collapse
Affiliation(s)
- Assunta Maria Casale
- Department of Biology and Biotechnology "C. Darwin", Sapienza University of Rome, Rome, Italy.
| | - Ugo Cappucci
- Department of Biology and Biotechnology "C. Darwin", Sapienza University of Rome, Rome, Italy
| | - Lucia Piacentini
- Department of Biology and Biotechnology "C. Darwin", Sapienza University of Rome, Rome, Italy.
| |
Collapse
|
8
|
Abstract
The eukaryotic genome is packaged into transcriptionally active euchromatin and silent heterochromatin, with most studies focused on the former encompassing the majority of protein-coding genes. The recent development of various sequencing techniques has refined this classic dichromatic partition and has better illuminated the composition, establishment, and evolution of this genomic and epigenomic "dark matter" in the context of topologically associated domains and phase-separated droplets. Heterochromatin includes genomic regions that can be densely stained by chemical dyes, which have been shown to be enriched for repetitive elements and epigenetic marks, including H3K9me2/3 and H3K27me3. Heterochromatin is usually replicated late, concentrated at the nuclear periphery or around nucleoli, and usually lacks highly expressed genes; and now it is considered to be as neither genetically inert nor developmentally static. Heterochromatin guards genome integrity against transposon activities and exerts important regulatory functions by targeting beyond its contained genes. Both its nucleotide sequences and regulatory proteins exhibit rapid coevolution between species. In addition, there are dynamic transitions between euchromatin and heterochromatin during developmental and evolutionary processes. We summarize here the ever-changing characteristics of heterochromatin and propose models and principles for the evolutionary transitions of heterochromatin that have been mainly learned from studies of Drosophila and yeast. Finally, we highlight the role of sex chromosomes in studying heterochromatin evolution.
Collapse
Affiliation(s)
- Jing Liu
- MOE Laboratory of Biosystems Homeostasis & Protection, Life Sciences InstituteZhejiang UniversityHangzhouChina
- Department of Molecular Evolution and DevelopmentUniversity of ViennaViennaAustria
| | - Mujahid Ali
- Department of Molecular Evolution and DevelopmentUniversity of ViennaViennaAustria
| | - Qi Zhou
- MOE Laboratory of Biosystems Homeostasis & Protection, Life Sciences InstituteZhejiang UniversityHangzhouChina
- Department of Molecular Evolution and DevelopmentUniversity of ViennaViennaAustria
- Center for Reproductive Medicine, The 2nd Affiliated Hospital, School of MedicineZhejiang UniversityHangzhouChina
| |
Collapse
|
9
|
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: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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.
Collapse
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.)
| |
Collapse
|
10
|
Ilyin AA, Stolyarenko AD, Klenov MS, Shevelyov YY. Various modes of HP1a interactions with the euchromatic chromosome arms in Drosophila ovarian somatic cells. Chromosoma 2020; 129:201-214. [PMID: 32500264 DOI: 10.1007/s00412-020-00738-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Revised: 05/05/2020] [Accepted: 05/26/2020] [Indexed: 12/20/2022]
Abstract
Heterochromatin protein 1a (HP1a) is a well-known component of pericentromeric and telomeric heterochromatin in Drosophila. However, its role and the mechanisms of its binding in the chromosome arms (ChAs) remain largely unclear. Here, we identified HP1a-interacting domains in the somatic cells of Drosophila ovaries using a DamID-seq approach and compared them with insertion sites of transposable elements (TEs) revealed by genome sequencing. Although HP1a domains cover only 13% of ChAs, they non-randomly associate with 42% of TE insertions. Furthermore, HP1a on average propagates at 2-kb distances from the TE insertions. These data confirm the role of TEs in formation of HP1a islands in ChAs. However, only 18% of HP1a domains have adjacent TEs, indicating the existence of other mechanisms of HP1a domain formation besides spreading from TEs. In particular, many TE-independent HP1a domains correspond to the regions attached to the nuclear pore complexes (NPCs) or contain active gene promoters. However, HP1a occupancy on the promoters does not significantly influence expression of corresponding genes. At the same time, the steady-state transcript level of many genes located outside of HP1a domains was altered upon HP1a knockdown in the somatic cells of ovaries, thus pointing to the strong indirect effect of HP1a depletion. Collectively, our results support an existence of at least three different mechanisms of HP1a domain emergence in ChAs: spreading from TE insertions, transient interactions with the chromatin located near NPCs, and targeting to the promoters of moderately expressed genes.
Collapse
Affiliation(s)
- Artem A Ilyin
- Department of Molecular Genetics of Cell, Institute of Molecular Genetics, Russian Academy of Sciences, Kurchatov Sq. 2, Moscow, Russia, 123182
| | - Anastasia D Stolyarenko
- Department of Molecular Genetics of Cell, Institute of Molecular Genetics, Russian Academy of Sciences, Kurchatov Sq. 2, Moscow, Russia, 123182
| | - Mikhail S Klenov
- Department of Molecular Genetics of Cell, Institute of Molecular Genetics, Russian Academy of Sciences, Kurchatov Sq. 2, Moscow, Russia, 123182.
| | - Yuri Y Shevelyov
- Department of Molecular Genetics of Cell, Institute of Molecular Genetics, Russian Academy of Sciences, Kurchatov Sq. 2, Moscow, Russia, 123182.
| |
Collapse
|
11
|
Di Mauro G, Carbonell A, Escudero-Ferruz P, Azorín F. The zinc-finger proteins WOC and ROW play distinct functions within the HP1c transcription complex. Biochim Biophys Acta Gene Regul Mech 2020; 1863:194492. [PMID: 32006714 DOI: 10.1016/j.bbagrm.2020.194492] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Revised: 01/28/2020] [Accepted: 01/29/2020] [Indexed: 11/20/2022]
Abstract
In Drosophila, the Heterochromatin Protein 1c (HP1c) forms a transcriptional complex with the zinc-finger proteins WOC and ROW, and the extraproteasomal ubiquitin receptor Dsk2. This complex localizes at promoters of active genes and it is required for transcription. The functions played by the different components of the HP1c complex are not fully understood. In this study we show that WOC and ROW are required for chromatin binding of both Dsk2 and HP1c. However, while impairing chromatin binding strongly destabilizes HP1c, it does not affect Dsk2 stability. We also show that WOC, but not ROW, is required for nuclear localization of Dsk2. Moreover, WOC and Dsk2 co-immunoprecitate upon ROW depletion. These results suggest that WOC and Dsk2 interact to form a subcomplex that mediates nuclear translocation of Dsk2. We also show that ROW mediates chromatin binding of the WOC/Dsk2 subcomplex, as well as of HP1c. Altogether these observations favor a model by which the interaction with WOC recruits Dsk2 to the HP1c complex that, in its turn, binds chromatin in a ROW-dependent manner.
Collapse
Affiliation(s)
- Gianmarco Di Mauro
- Institute of Molecular Biology of Barcelona, CSIC, Baldiri Reixac, 10-12, 08028 Barcelona, Spain; Institute for Research in Biomedicine, IRB Barcelona, The Barcelona Institute for Science and Technology, Baldiri Reixac, 10-12, 08028 Barcelona, Spain
| | - Albert Carbonell
- Institute of Molecular Biology of Barcelona, CSIC, Baldiri Reixac, 10-12, 08028 Barcelona, Spain; Institute for Research in Biomedicine, IRB Barcelona, The Barcelona Institute for Science and Technology, Baldiri Reixac, 10-12, 08028 Barcelona, Spain
| | - Paula Escudero-Ferruz
- Institute of Molecular Biology of Barcelona, CSIC, Baldiri Reixac, 10-12, 08028 Barcelona, Spain; Institute for Research in Biomedicine, IRB Barcelona, The Barcelona Institute for Science and Technology, Baldiri Reixac, 10-12, 08028 Barcelona, Spain
| | - Fernando Azorín
- Institute of Molecular Biology of Barcelona, CSIC, Baldiri Reixac, 10-12, 08028 Barcelona, Spain; Institute for Research in Biomedicine, IRB Barcelona, The Barcelona Institute for Science and Technology, Baldiri Reixac, 10-12, 08028 Barcelona, Spain.
| |
Collapse
|
12
|
Zimmermann MT, Williams MM, Klee EW, Lomberk GA, Urrutia R. Modeling post-translational modifications and cancer-associated mutations that impact the heterochromatin protein 1α-importin α heterodimers. Proteins 2019; 87:904-916. [PMID: 31152607 PMCID: PMC6790107 DOI: 10.1002/prot.25752] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Accepted: 05/27/2019] [Indexed: 12/27/2022]
Abstract
Heterochromatin protein 1α (HP1α) is a protein that mediates cancer-associated processes in the cell nucleus. Proteomic experiments, reported here, demonstrate that HP1α complexes with importin α (IMPα), a protein necessary for its nuclear transport. This data is congruent with Simple Linear Motif (SLiM) analyses that identify an IMPα-binding motif within the linker that joins the two globular domains of this protein. Using molecular modeling and dynamics simulations, we develop a model of the IMPα-HP1α complex and investigate the impact of phosphorylation and genomic variants on their interaction. We demonstrate that phosphorylation of the HP1α linker likely regulates its association with IMPα, which has implications for HP1α access to the nucleus, where it functions. Cancer-associated genomic variants do not abolish the interaction of HP1α but instead lead to rearrangements where the variant proteins maintain interaction with IMPα, but with less specificity. Combined, this new mechanistic insight bears biochemical, cell biological, and biomedical relevance.
Collapse
Affiliation(s)
- Michael T. Zimmermann
- Bioinformatics Research and Development Laboratory, and Precision Medicine Simulation Unit, Genomic Science and Precision Medicine Center (GSPMC)Medical College of WisconsinMilwaukeeWisconsin
- Clinical and Translational Sciences InstituteMedical College of WisconsinMilwaukeeWisconsin
| | - Monique M. Williams
- Department of BiochemistryMayo ClinicRochesterMinnesota
- Division of Biomedical Statistics and InformaticsMayo ClinicRochesterMinnesota
| | - Eric W. Klee
- Department of BiochemistryMayo ClinicRochesterMinnesota
- Division of Biomedical Statistics and InformaticsMayo ClinicRochesterMinnesota
| | - Gwen A. Lomberk
- Division of Research, Department of SurgeryMedical College of WisconsinMilwaukeeWisconsin
- Department of Pharmacology and ToxicologyMedical College of WisconsinMilwaukeeWisconsin
- Genomic Science and Precision Medicine Center (GSPMC)Medical College of WisconsinMilwaukeeWisconsin
| | - Raul Urrutia
- Division of Research, Department of SurgeryMedical College of WisconsinMilwaukeeWisconsin
- Genomic Science and Precision Medicine Center (GSPMC)Medical College of WisconsinMilwaukeeWisconsin
- Department of BiochemistryMedical College of WisconsinMilwaukeeWisconsin
| |
Collapse
|
13
|
Wojtala M, Dąbek A, Rybaczek D, Śliwińska A, Świderska E, Słapek K, El-Osta A, Balcerczyk A. Silencing Lysine-Specific Histone Demethylase 1 (LSD1) Causes Increased HP1-Positive Chromatin, Stimulation of DNA Repair Processes, and Dysregulation of Proliferation by Chk1 Phosphorylation in Human Endothelial Cells. Cells 2019; 8:E1212. [PMID: 31591366 DOI: 10.3390/cells8101212] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2019] [Revised: 09/21/2019] [Accepted: 09/30/2019] [Indexed: 12/13/2022] Open
Abstract
The methylation of histone lysine residues modifies chromatin conformation and regulates the expression of genes implicated in cell metabolism. Lysine-specific demethylase 1 (LSD1) is a flavin-dependent monoamine oxidase that can demethylate mono- and dimethylated histone lysines 4 and 9 (H3K4 and H3K9). The removal of methyl groups from the lysine residues of histone and non-histone proteins was found to be an important regulatory factor of cell proliferation. However, its role has not been fully elucidated. In this study, we assessed LSD1-mediated cell cycle progression using a human endothelial cell model. The short hairpin RNA knockdown of LSD1 inhibits the G2/M phase of cell cycle progression by checkpoint kinase 1 (Chk1) phosphorylation (S137). We observed elevated DNA damage, which was consistent with the increased detection of double-strand breaks as well as purines and pyrimidines oxidation, which accompanied the activation of ATR/ATRIP signaling by H2AXS139 phosphorylation. The irreversible pharmacological inhibition of LSD1 by 2-phenylcyclopropylamine (2-PCPA) inactivated its enzymatic activity, causing significant changes in heterochromatin and euchromatin conformation assessed by chromatin assembly factor 1 subunit A (CAF1A) and heterochromatin protein 1 isoform α and γ (HP1α/γ) immunofluorescence analysis. We conclude that the knockdown of LSD1 in endothelial cells leads to increased HP1-positive chromatin, the stimulation of DNA repair processes, and the dysregulation of proliferation machinery.
Collapse
|
14
|
Li J, Ha S, Li Z, Huang Y, Lin E, Xiao W. Aurora B prevents aneuploidy via MAD2 during the first mitotic cleavage in oxidatively damaged embryos. Cell Prolif 2019; 52:e12657. [PMID: 31264311 PMCID: PMC6797512 DOI: 10.1111/cpr.12657] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2019] [Revised: 05/07/2019] [Accepted: 05/27/2019] [Indexed: 02/05/2023] Open
Abstract
OBJECTIVES A high rate of chromosome aneuploidy is exhibited in in vitro fertilization (IVF)-derived embryos. Our previous experiments suggested that reactive oxygen species (ROS) can activate Mad2, a key protein in the spindle assembly checkpoint (SAC), and delay the first mitotic, providing time to prevent the formation of embryonic aneuploidy. We aimed to determine whether mitotic kinase Aurora B was involved in the SAC function to prevent aneuploidy in IVF-derived embryos. MATERIALS AND METHODS We analysed aneuploidy formation and repair during embryo pre-implantation via 4',6-diamidino-2-phenylindole (DAPI) staining and karyotype analysis. We assessed Aurora B activation by immunofluorescence and investigated the effect of Aurora B inhibition on embryo injury-related variables, such as embryonic development, ROS levels, mitochondrial membrane potential and γH2AX-positive expression. RESULTS We observed the expression and phosphorylation of Thr232 in Aurora B in oxidative stress-induced zygotes. Moreover, inhibition of Aurora B caused chromosome mis-segregation, abnormal spindle structures, abnormal chromosome number and reduced expression of Mad2 in IVF embryos. Our results suggest that Aurora B causes mitotic arrest and participates in SAC via Mad2 and H3S10P, which is required for self-correction of aneuploidies. CONCLUSIONS We demonstrate here that oxidative stress-induced DNA damage triggers Aurora B-mediated activation of SAC, which prevents aneuploidy at the first mitotic cleavage in early mouse IVF embryos.
Collapse
Affiliation(s)
- Jiena Li
- Reproductive Center, The First Affiliated Hospital of Shantou University Medical CollegeShantou UniversityShantouChina
| | - Siyao Ha
- Laboratory for Reproductive Immunology, Hospital & Institute of Obstetrics & GynecologyFudan University Shanghai Medical CollegeShanghaiChina
| | - Zhiling Li
- Reproductive Center, The First Affiliated Hospital of Shantou University Medical CollegeShantou UniversityShantouChina
| | - Yue Huang
- Reproductive Center, The First Affiliated Hospital of Shantou University Medical CollegeShantou UniversityShantouChina
| | - En Lin
- Reproductive Center, The First Affiliated Hospital of Shantou University Medical CollegeShantou UniversityShantouChina
| | - Wanfen Xiao
- Reproductive Center, The First Affiliated Hospital of Shantou University Medical CollegeShantou UniversityShantouChina
| |
Collapse
|
15
|
Casale AM, Cappucci U, Fanti L, Piacentini L. Heterochromatin protein 1 (HP1) is intrinsically required for post-transcriptional regulation of Drosophila Germline Stem Cell (GSC) maintenance. Sci Rep 2019; 9:4372. [PMID: 30867469 DOI: 10.1038/s41598-019-40152-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Accepted: 02/07/2019] [Indexed: 01/05/2023] Open
Abstract
A very important open question in stem cells regulation is how the fine balance between GSCs self-renewal and differentiation is orchestrated at the molecular level. In the past several years much progress has been made in understanding the molecular mechanisms underlying intrinsic and extrinsic controls of GSC regulation but the complex gene regulatory networks that regulate stem cell behavior are only partially understood. HP1 is a dynamic epigenetic determinant mainly involved in heterochromatin formation, epigenetic gene silencing and telomere maintenance. Furthermore, recent studies have revealed the importance of HP1 in DNA repair, sister chromatid cohesion and, surprisingly, in positive regulation of gene expression. Here, we show that HP1 plays a crucial role in the control of GSC homeostasis in Drosophila. Our findings demonstrate that HP1 is required intrinsically to promote GSC self-renewal and progeny differentiation by directly stabilizing the transcripts of key genes involved in GSCs maintenance.
Collapse
|
16
|
Lee DH, Ryu HW, Kim GW, Kwon SH. Comparison of three heterochromatin protein 1 homologs in Drosophila. J Cell Sci 2019; 132:jcs.222729. [PMID: 30659116 DOI: 10.1242/jcs.222729] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Accepted: 12/22/2018] [Indexed: 01/20/2023] Open
Abstract
Heterochromatin protein 1 (HP1) is an epigenetic regulator of chromatin structure and genome function in eukaryotes. Despite shared features, most eukaryotes have a minimum of three HP1 homologs with differential localization patterns and functions. Most studies focus on Drosophila HP1a [also known as Su(var)205], and little is known about the properties of HP1b and HP1c. To determine the features of the three HP1 homologs, we performed the first comprehensive comparative analysis of Drosophila HP1 homologs. HP1 differentially homodimerizes and heterodimerizes in vivo and in vitro HP1b and HP1c, but not HP1a, are localized to both the nucleus and cytoplasm. The C-terminal extension region (CTE) targets HP1c and HP1b to the cytoplasm. Biochemical approaches show that HP1 binds to various interacting partners with different binding affinities. Each HP1 associates differently with RNA polymerase II; a gene reporter assay revealed that HP1a and HP1b, but not HP1c, inhibit transcriptional activity, suggesting that HP1c serves as a positive regulator in transcription. Thus, these studies provide the basic clues pertaining to the molecular mechanism by which HP1 might control cellular processes in a homolog-specific manner.
Collapse
Affiliation(s)
- Dong Hoon Lee
- College of Pharmacy, Yonsei Institute of Pharmaceutical Sciences, Yonsei University, Incheon, 21983, Republic of Korea.,Department of Integrated OMICS for Biomedical Science, Yonsei University, Seoul 03722, Republic of Korea
| | - Hyun Wook Ryu
- College of Pharmacy, Yonsei Institute of Pharmaceutical Sciences, Yonsei University, Incheon, 21983, Republic of Korea
| | - Go Woon Kim
- College of Pharmacy, Yonsei Institute of Pharmaceutical Sciences, Yonsei University, Incheon, 21983, Republic of Korea
| | - So Hee Kwon
- College of Pharmacy, Yonsei Institute of Pharmaceutical Sciences, Yonsei University, Incheon, 21983, Republic of Korea .,Department of Integrated OMICS for Biomedical Science, Yonsei University, Seoul 03722, Republic of Korea
| |
Collapse
|
17
|
Armstrong RL, Penke TJR, Chao SK, Gentile GM, Strahl BD, Matera AG, McKay DJ, Duronio RJ. H3K9 Promotes Under-Replication of Pericentromeric Heterochromatin in Drosophila Salivary Gland Polytene Chromosomes. Genes (Basel) 2019; 10:E93. [PMID: 30700014 DOI: 10.3390/genes10020093] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 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.
Collapse
|
18
|
Park AR, Liu N, Neuenkirchen N, Guo Q, Lin H. The Role of Maternal HP1a in Early Drosophila Embryogenesis via Regulation of Maternal Transcript Production. Genetics 2019; 211:201-17. [PMID: 30442760 DOI: 10.1534/genetics.118.301704] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2018] [Accepted: 11/07/2018] [Indexed: 11/18/2022] Open
Abstract
Heterochromatin protein 1a (HP1a) is a highly conserved and versatile epigenetic factor that can both silence and activate transcription. However, the function of HP1a in development has been underinvestigated. Here, we report the role of maternal HP1a in producing maternal transcripts that drive early Drosophila embryogenesis. Maternal HP1a upregulates genes involved in translation, mRNA splicing, and cell division, but downregulates genes involved in neurogenesis, organogenesis, and germline development, which all occur later in development. Our study reveals the earliest contribution of HP1a during oogenesis in regulating the production of maternal transcripts that drive early Drosophila embryogenesis.
Collapse
|
19
|
Pindyurin AV, Ilyin AA, Ivankin AV, Tselebrovsky MV, Nenasheva VV, Mikhaleva EA, Pagie L, van Steensel B, Shevelyov YY. The large fraction of heterochromatin in Drosophila neurons is bound by both B-type lamin and HP1a. Epigenetics Chromatin 2018; 11:65. [PMID: 30384843 PMCID: PMC6211408 DOI: 10.1186/s13072-018-0235-8] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Accepted: 10/26/2018] [Indexed: 12/22/2022] Open
Abstract
Background In most mammalian cell lines, chromatin located at the nuclear periphery is represented by condensed heterochromatin, as evidenced by microscopy observations and DamID mapping of lamina-associated domains (LADs) enriched in dimethylated Lys9 of histone H3 (H3K9me2). However, in Kc167 cell culture, the only Drosophilla cell type where LADs have previously been mapped, they are neither H3K9me2-enriched nor overlapped with the domains of heterochromatin protein 1a (HP1a). Results Here, using cell type-specific DamID we mapped genome-wide LADs, HP1a and Polycomb (Pc) domains from the central brain, Repo-positive glia, Elav-positive neurons and the fat body of Drosophila third instar larvae. Strikingly, contrary to Kc167 cells of embryonic origin, in neurons and, to a lesser extent, in glia and the fat body, HP1a domains appear to overlap strongly with LADs in both the chromosome arms and pericentromeric regions. Accordingly, centromeres reside closer to the nuclear lamina in neurons than in Kc167 cells. As expected, active gene promoters are mostly not present in LADs, HP1a and Pc domains. These domains are occupied by silent or weakly expressed genes with genes residing in the HP1a-bound LADs expressed at the lowest level. Conclusions In various differentiated Drosophila cell types, we discovered the existence of peripheral heterochromatin, similar to that observed in mammals. Our findings support the model that peripheral heterochromatin matures enhancing the repression of unwanted genes as cells terminally differentiate. Electronic supplementary material The online version of this article (10.1186/s13072-018-0235-8) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Alexey V Pindyurin
- Division of Gene Regulation, Netherlands Cancer Institute, 1066 CX, Amsterdam, The Netherlands. .,Department of Regulation of Genetic Processes, Institute of Molecular and Cellular Biology, Siberian Branch of Russian Academy of Sciences, Novosibirsk, Russia, 630090. .,Laboratory of Structural, Functional and Comparative Genomics, Novosibirsk State University, Novosibirsk, Russia, 630090.
| | - Artem A Ilyin
- Department of Molecular Genetics of Cell, Institute of Molecular Genetics, Russian Academy of Sciences, Moscow, Russia, 123182
| | - Anton V Ivankin
- Department of Regulation of Genetic Processes, Institute of Molecular and Cellular Biology, Siberian Branch of Russian Academy of Sciences, Novosibirsk, Russia, 630090
| | - Mikhail V Tselebrovsky
- Department of Molecular Genetics of Cell, Institute of Molecular Genetics, Russian Academy of Sciences, Moscow, Russia, 123182.,QC Biochemistry Lab, Yaroslavl Pharmaceutical Complex for Production of Finished Dosage Forms, R-Pharm Group, Yaroslavl, Russia, 150061
| | - Valentina V Nenasheva
- Department of Viral and Cellular Molecular Genetics, Institute of Molecular Genetics, Russian Academy of Sciences, Moscow, Russia, 123182
| | - Elena A Mikhaleva
- Department of Molecular Genetics of Cell, Institute of Molecular Genetics, Russian Academy of Sciences, Moscow, Russia, 123182
| | - Ludo Pagie
- Division of Gene Regulation, Netherlands Cancer Institute, 1066 CX, Amsterdam, The Netherlands
| | - Bas van Steensel
- Division of Gene Regulation, Netherlands Cancer Institute, 1066 CX, Amsterdam, The Netherlands.,Department of Cell Biology, Erasmus University Medical Center, 3015 GE, Rotterdam, The Netherlands
| | - Yuri Y Shevelyov
- Department of Molecular Genetics of Cell, Institute of Molecular Genetics, Russian Academy of Sciences, Moscow, Russia, 123182.
| |
Collapse
|
20
|
Wojtala M, Macierzyńska-Piotrowska E, Rybaczek D, Pirola L, Balcerczyk A. Pharmacological and transcriptional inhibition of the G9a histone methyltransferase suppresses proliferation and modulates redox homeostasis in human microvascular endothelial cells. Pharmacol Res 2018; 128:252-263. [DOI: 10.1016/j.phrs.2017.10.014] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Revised: 07/27/2017] [Accepted: 10/26/2017] [Indexed: 12/25/2022]
|
21
|
Vo N, Anh Suong DN, Yoshino N, Yoshida H, Cotterill S, Yamaguchi M. Novel roles of HP1a and Mcm10 in DNA replication, genome maintenance and photoreceptor cell differentiation. Nucleic Acids Res 2017; 45:1233-1254. [PMID: 28180289 PMCID: PMC5388399 DOI: 10.1093/nar/gkw1174] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Revised: 11/04/2016] [Accepted: 11/13/2016] [Indexed: 01/21/2023] Open
Abstract
Both Mcm10 and HP1a are known to be required for DNA replication. However, underlying mechanism is not clarified yet especially for HP1. Knockdown of both HP1a and Mcm10 genes inhibited the progression of S phase in Drosophila eye imaginal discs. Proximity Ligation Assay (PLA) demonstrated that HP1a is in close proximity to DNA replication proteins including Mcm10, RFC140 and DNA polymerase ε 255 kDa subunit in S-phase. This was further confirmed by co-immunoprecipitation assay. The PLA signals between Mcm10 and HP1a are specifically observed in the mitotic cycling cells, but not in the endocycling cells. Interestingly, many cells in the posterior regions of eye imaginal discs carrying a double knockdown of Mcm10 and HP1a induced ectopic DNA synthesis and DNA damage without much of ectopic apoptosis. Therefore, the G1-S checkpoint may be affected by knockdown of both proteins. This event was also the case with other HP family proteins such as HP4 and HP6. In addition, both Mcm10 and HP1a are required for differentiation of photoreceptor cells R1, R6 and R7. Further analyses on several developmental genes involved in the photoreceptor cell differentiation suggest that a role of both proteins is mediated by regulation of the lozenge gene.
Collapse
Affiliation(s)
- Nicole Vo
- Department of Applied Biology, Kyoto Institute of Technology, Kyoto, Japan.,The Center for Advanced Insect Research, Kyoto Institute of Technology, Kyoto, Japan
| | - Dang Ngoc Anh Suong
- Department of Applied Biology, Kyoto Institute of Technology, Kyoto, Japan.,The Center for Advanced Insect Research, Kyoto Institute of Technology, Kyoto, Japan
| | - Natsuki Yoshino
- Department of Applied Biology, Kyoto Institute of Technology, Kyoto, Japan.,The Center for Advanced Insect Research, Kyoto Institute of Technology, Kyoto, Japan
| | - Hideki Yoshida
- Department of Applied Biology, Kyoto Institute of Technology, Kyoto, Japan.,The Center for Advanced Insect Research, Kyoto Institute of Technology, Kyoto, Japan
| | - Sue Cotterill
- Department of Basic Medical Sciences, St Georges, University of London, London, UK
| | - Masamitsu Yamaguchi
- Department of Applied Biology, Kyoto Institute of Technology, Kyoto, Japan.,The Center for Advanced Insect Research, Kyoto Institute of Technology, Kyoto, Japan
| |
Collapse
|
22
|
Yang Z, Sun J, Hu Y, Wang F, Wang X, Qiao HH, Xu J, Mao D, Ren X, Pan LX, Xu RG, Xu BW, Zhang Y, Li H, Miao W, Hu Y, Chang Z, Wang D, Li H, Chang Z, Liu LP, Liu Q, Ni JQ. Histone H1 defect in escort cells triggers germline tumor in Drosophila ovary. Dev Biol 2017; 424:40-9. [PMID: 28232075 DOI: 10.1016/j.ydbio.2017.02.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Revised: 02/19/2017] [Accepted: 02/19/2017] [Indexed: 12/19/2022]
Abstract
Drosophila ovary is recognized as one of the best model systems to study stem cell biology in vivo. We had previously identified an autonomous role of the histone H1 in germline stem cell (GSC) maintenance. Here, we found that histone H1 depletion in escort cells (ECs) resulted in an increase of spectrosome-containing cells (SCCs), an ovary tumor-like phenotype. Further analysis showed that the Dpp pathway is excessively activated in these SCC cells, while the expression of bam is attenuated. In the H1-depleted ECs, both transposon activity and DNA damage had increased dramatically, followed by EC apoptosis, which is consistent with the role of H1 in other somatic cells. Surprisingly, H1-depleted ECs acquired cap cell characteristics including dpp expression, and the resulting abnormal Dpp level inhibits SCC further differentiation. Most interestingly, double knockdown of H1 and dpp in ECs can reduce the number of SCCs to the normal level, indicating that the additional Dpp secreted by ECs contributes to the germline tumor. Taken together, our findings indicate that histone H1 is an important epigenetic factor in controlling EC characteristics and a key suppressor of germline tumor.
Collapse
|
23
|
Feng J, Lu J. LHP1 Could Act as an Activator and a Repressor of Transcription in Plants. Front Plant Sci 2017; 8:2041. [PMID: 29234344 PMCID: PMC5712405 DOI: 10.3389/fpls.2017.02041] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Accepted: 11/14/2017] [Indexed: 05/19/2023]
Abstract
Polycomb group (PcG) proteins within the polycomb repressive complex 1 (PRC1) and PRC2 are significant epigenetic regulatory factors involved in important cellular and developmental processes in eukaryotes. In Arabidopsis, LIKE HETEROCHROMATIN PROTEIN 1 (LHP1), also known as TERMINAL FLOWER 2, has been proposed as a plant specific subunit of PRC1 that could bind the trimethylated lysine 27 of histone H3 (H3K27me3), which is established by PRC2 and is required for a functional plant PcG system. LHP1 not only interacts with PRC1 to catalyze monoubiquitination at lysine 119 of histone H2A but also functions with PRC2 to establish H3K27me3. This review is about the interaction of LHP1 with PRC1 and PRC2, in which LHP1 may act as a bridge between the two. Meantime, this review highlights that LHP1 could act as an activator and a repressor of transcription.
Collapse
Affiliation(s)
- Jing Feng
- Guangxi Crop Genetic Improvement and Biotechnology Laboratory, Guangxi Academy of Agricultural Sciences, Nanning, China
- *Correspondence: Jiang Lu, Jing Feng,
| | - Jiang Lu
- Guangxi Crop Genetic Improvement and Biotechnology Laboratory, Guangxi Academy of Agricultural Sciences, Nanning, China
- Center for Viticulture and Enology, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China
- *Correspondence: Jiang Lu, Jing Feng,
| |
Collapse
|
24
|
Abramov YA, Shatskikh AS, Maksimenko OG, Bonaccorsi S, Gvozdev VA, Lavrov SA. The Differences Between Cis- and Trans-Gene Inactivation Caused by Heterochromatin in Drosophila. Genetics 2016; 202:93-106. [PMID: 26500261 DOI: 10.1534/genetics.115.181693] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Accepted: 10/13/2015] [Indexed: 11/18/2022] Open
Abstract
Position-effect variegation (PEV) is the epigenetic disruption of gene expression near the de novo-formed euchromatin-heterochromatin border. Heterochromatic cis-inactivation may be accompanied by the trans-inactivation of genes on a normal homologous chromosome in trans-heterozygous combination with a PEV-inducing rearrangement. We characterize a new genetic system, inversion In(2)A4, demonstrating cis-acting PEV as well as trans-inactivation of the reporter transgenes on the homologous nonrearranged chromosome. The cis-effect of heterochromatin in the inversion results not only in repression but also in activation of genes, and it varies at different developmental stages. While cis-actions affect only a few juxtaposed genes, trans-inactivation is observed in a 500-kb region and demonstrates а nonuniform pattern of repression with intermingled regions where no transgene repression occurs. There is no repression around the histone gene cluster and in some other euchromatic sites. trans-Inactivation is accompanied by dragging of euchromatic regions into the heterochromatic compartment, but the histone gene cluster, located in the middle of the trans-inactivated region, was shown to be evicted from the heterochromatin. We demonstrate that trans-inactivation is followed by de novo HP1a accumulation in the affected transgene; trans-inactivation is specifically favored by the chromatin remodeler SAYP and prevented by Argonaute AGO2.
Collapse
|
25
|
Bodega G, Segura B, Ciordia S, Mena MDC, López-Fernández LA, García MI, Trabado I, Suárez I. Ammonia Affects Astroglial Proliferation in Culture. PLoS One 2015; 10:e0139619. [PMID: 26421615 PMCID: PMC4589356 DOI: 10.1371/journal.pone.0139619] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Accepted: 09/14/2015] [Indexed: 11/19/2022] Open
Abstract
Primary cultures of rat astroglial cells were exposed to 1, 3 and 5 mM NH4Cl for up to 10 days. Dose- and time-dependent reductions in cell numbers were seen, plus an increase in the proportion of cells in the S phase. The DNA content was reduced in the treated cells, and BrdU incorporation diminished. However, neither ammonia nor ammonia plus glutamine had any effect on DNA polymerase activity. iTRAQ analysis showed that exposure to ammonia induced a significant reduction in histone and heterochromatin protein 1 expression. A reduction in cell viability was also noted. The ammonia-induced reduction of proliferative activity in these cultured astroglial cells seems to be due to a delay in the completion of the S phase provoked by the inhibition of chromatin protein synthesis.
Collapse
Affiliation(s)
- Guillermo Bodega
- Departamento de Biomedicina y Biotecnología, Universidad de Alcalá, 28871 Alcalá de Henares, Madrid, Spain
- * E-mail:
| | - Berta Segura
- Instituto de Salud Carlos III, UFIEC, Unidad de Neuro-Oncología, 28220 Majadahonda, Madrid, Spain
| | - Sergio Ciordia
- Proteomics, Centro Nacional de Biotecnología/CSIC, Campus de Cantoblanco, Madrid, Spain
| | - María del Carmen Mena
- Proteomics, Centro Nacional de Biotecnología/CSIC, Campus de Cantoblanco, Madrid, Spain
| | - Luis Andrés López-Fernández
- Servicio de Farmacia, Instituto de Investigación Sanitaria Gregorio Marañón, Hospital General Universitario Gregorio Marañón, Madrid, Spain
| | - María Isabel García
- Servicio de Farmacia, Instituto de Investigación Sanitaria Gregorio Marañón, Hospital General Universitario Gregorio Marañón, Madrid, Spain
| | - Isabel Trabado
- Unidad de Cultivos, Facultad de Medicina, Universidad de Alcalá, 28871 Alcalá de Henares, Madrid, Spain
| | - Isabel Suárez
- Departamento de Biomedicina y Biotecnología, Universidad de Alcalá, 28871 Alcalá de Henares, Madrid, Spain
| |
Collapse
|
26
|
Gacek-Matthews A, Noble LM, Gruber C, Berger H, Sulyok M, Marcos AT, Strauss J, Andrianopoulos A. KdmA, a histone H3 demethylase with bipartite function, differentially regulates primary and secondary metabolism in Aspergillus nidulans. Mol Microbiol 2015; 96:839-60. [PMID: 25712266 PMCID: PMC4949671 DOI: 10.1111/mmi.12977] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/17/2015] [Indexed: 12/28/2022]
Abstract
Aspergillus nidulans kdmA encodes a member of the KDM4 family of jumonji histone demethylase proteins, highly similar to metazoan orthologues both within functional domains and in domain architecture. This family of proteins exhibits demethylase activity towards lysines 9 and 36 of histone H3 and plays a prominent role in gene expression and chromosome structure in many species. Mass spectrometry mapping of A. nidulans histones revealed that around 3% of bulk histone H3 carried trimethylated H3K9 (H3K9me3) but more than 90% of histones carried either H3K36me2 or H3K36me3. KdmA functions as H3K36me3 demethylase and has roles in transcriptional regulation. Genetic manipulation of KdmA levels is tolerated without obvious effect in most conditions, but strong phenotypes are evident under various conditions of stress. Transcriptome analysis revealed that – in submerged early and late cultures – between 25% and 30% of the genome is under KdmA influence respectively. Transcriptional imbalance in the kdmA deletion mutant may contribute to the lethal phenotype observed upon exposure of mutant cells to low‐density visible light on solid medium. Although KdmA acts as transcriptional co‐repressor of primary metabolism genes, it is required for full expression of several genes involved in biosynthesis of secondary metabolites.
Collapse
Affiliation(s)
- Agnieszka Gacek-Matthews
- Fungal Genetics and Genomics Unit, Department of Applied Genetics and Cell Biology, BOKU-University of Natural Resources and Life Sciences, Campus Tulln, Tulln, 3430, Austria
| | - Luke M Noble
- Department of Genetics, University of Melbourne, Victoria, 3010, Australia
| | - Clemens Gruber
- Department of Chemistry, BOKU-University of Natural Resources and Life Sciences, Campus Muthgasse, Vienna, A-1190, Austria
| | - Harald Berger
- Health and Environment Department, AIT - Austrian Institute of Technology GmbH, Campus Tulln, Tulln, 3430, Austria
| | - Michael Sulyok
- Center for Analytical Chemistry, Department IFA Tulln, BOKU-University of Natural Resources and Life Sciences, Campus Tulln, Tulln, 3430, Austria
| | - Ana T Marcos
- Departamento de Genética, Facultad de Biología, Universidad de Sevilla, Sevilla, 41012, Spain
| | - Joseph Strauss
- Fungal Genetics and Genomics Unit, Department of Applied Genetics and Cell Biology, BOKU-University of Natural Resources and Life Sciences, Campus Tulln, Tulln, 3430, Austria.,Health and Environment Department, AIT - Austrian Institute of Technology GmbH, Campus Tulln, Tulln, 3430, Austria
| | | |
Collapse
|
27
|
Chen S, Wang C, Sun L, Wang DL, Chen L, Huang Z, Yang Q, Gao J, Yang XB, Chang JF, Chen P, Lan L, Mao Z, Sun FL. RAD6 promotes homologous recombination repair by activating the autophagy-mediated degradation of heterochromatin protein HP1. Mol Cell Biol 2015; 35:406-16. [PMID: 25384975 DOI: 10.1128/MCB.01044-14] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Efficient DNA double-strand break (DSB) repair is critical for the maintenance of genome stability. Unrepaired or misrepaired DSBs cause chromosomal rearrangements that can result in severe consequences, such as tumorigenesis. RAD6 is an E2 ubiquitin-conjugating enzyme that plays a pivotal role in repairing UV-induced DNA damage. Here, we present evidence that RAD6 is also required for DNA DSB repair via homologous recombination (HR) by specifically regulating the degradation of heterochromatin protein 1α (HP1α). Our study indicates that RAD6 physically interacts with HP1α and ubiquitinates HP1α at residue K154, thereby promoting HP1α degradation through the autophagy pathway and eventually leading to an open chromatin structure that facilitates efficient HR DSB repair. Furthermore, bioinformatics studies have indicated that the expression of RAD6 and HP1α exhibits an inverse relationship and correlates with the survival rate of patients.
Collapse
|
28
|
Shoji K, Hara K, Kawamoto M, Kiuchi T, Kawaoka S, Sugano S, Shimada T, Suzuki Y, Katsuma S. Silkworm HP1a transcriptionally enhances highly expressed euchromatic genes via association with their transcription start sites. Nucleic Acids Res 2014; 42:11462-71. [PMID: 25237056 PMCID: PMC4191426 DOI: 10.1093/nar/gku862] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Heterochromatin protein 1 (HP1) is an evolutionarily conserved protein across different eukaryotic species and is crucial for heterochromatin establishment and maintenance. The silkworm, Bombyx mori, encodes two HP1 proteins, BmHP1a and BmHP1b. In order to investigate the role of BmHP1a in transcriptional regulation, we performed genome-wide analyses of the transcriptome, transcription start sites (TSSs), chromatin modification states and BmHP1a-binding sites of the silkworm ovary-derived BmN4 cell line. We identified a number of BmHP1a-binding loci throughout the silkworm genome and found that these loci included TSSs and frequently co-occurred with neighboring euchromatic histone modifications. In addition, we observed that genes with BmHP1a-associated TSSs were relatively highly expressed in BmN4 cells. RNA interference-mediated BmHP1a depletion resulted in the transcriptional repression of highly expressed genes with BmHP1a-associated TSSs, whereas genes not coupled with BmHP1a-binding regions were less affected by the treatment. These results demonstrate that BmHP1a binds near TSSs of highly expressed euchromatic genes and positively regulates their expression. Our study revealed a novel mode of transcriptional regulation mediated by HP1 proteins.
Collapse
Affiliation(s)
- Keisuke Shoji
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Kahori Hara
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Munetaka Kawamoto
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Takashi Kiuchi
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Shinpei Kawaoka
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Sumio Sugano
- Department of Medical Genome Sciences, Graduate School of Frontier Sciences, The University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan
| | - Toru Shimada
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Yutaka Suzuki
- Department of Medical Genome Sciences, Graduate School of Frontier Sciences, The University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan
| | - Susumu Katsuma
- Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan
| |
Collapse
|
29
|
Frost B, Hemberg M, Lewis J, Feany MB. Tau promotes neurodegeneration through global chromatin relaxation. Nat Neurosci 2014; 17:357-66. [PMID: 24464041 PMCID: PMC4012297 DOI: 10.1038/nn.3639] [Citation(s) in RCA: 314] [Impact Index Per Article: 31.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2013] [Accepted: 12/24/2013] [Indexed: 12/16/2022]
Abstract
The microtubule-associated protein tau is involved in a number of neurodegenerative disorders, including Alzheimer’s disease (AD). Previous studies link oxidative stress and subsequent DNA damage to neuronal death in AD and related tauopathies. Since DNA damage can significantly alter chromatin structure, we examined epigenetic changes in tau-induced neurodegeneration. We have found widespread loss of heterochromatin in tau transgenic Drosophila and mice, and in human AD. Importantly, genetic rescue of tau-induced heterochromatin loss substantially reduced neurodegeneration in Drosophila. We identified oxidative stress and subsequent DNA damage as a mechanistic link between transgenic tau expression and heterochromatin relaxation, and found that heterochromatin loss permits aberrant gene expression in tauopathies. Furthermore, large-scale analyses from human AD brains revealed a widespread transcriptional increase in genes that are heterochromatically silenced in controls. Our results establish heterochromatin loss as a toxic effector of tau-induced neurodegeneration, and identify chromatin structure as a potential therapeutic target in AD.
Collapse
Affiliation(s)
- Bess Frost
- Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Martin Hemberg
- Department of Ophthalmology and Program in Neurobiology, Boston Children's Hospital, Boston, Massachusetts, USA
| | - Jada Lewis
- Department of Neuroscience and Center for Translational Research in Neurodegenerative Disease, University of Florida, Gainesville, Florida, USA
| | - Mel B Feany
- Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| |
Collapse
|
30
|
Ruiz-Estévez M, Bakkali M, Cabrero J, Camacho JP, López-León MD. HP1 knockdown is associated with abnormal condensation of almost all chromatin types in a grasshopper (Eyprepocnemis plorans). Chromosome Res 2014; 22:253-66. [PMID: 24398928 DOI: 10.1007/s10577-013-9399-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2013] [Revised: 12/11/2013] [Accepted: 12/12/2013] [Indexed: 10/25/2022]
Abstract
Heterochromatin protein 1 (HP1) is a highly conserved family of eukaryotic proteins required for heterochromatic gene silencing and euchromatic gene transcription regulation. In addition, HP1 is involved in chromatin organization and protection of chromosome integrity during cell division. Here, we present a cytological and molecular analysis of the effects of HP1 knockdown in Eyprepocnemis plorans, a grasshopper species polymorphic for supernumerary heterochromatic chromosomes. Our results revealed contrasting effects of HP1 knockdown on gene activity. While the Bub1 gene decreased in expression level in HP1 knockdown animals, NOR activity, rRNA and, contrarily to previous reports in Drosophila, Hsp70 gene expression remained unchanged. Furthermore, HP1 knockdown resulted in abnormal chromatin condensation, chromosomal bridges, higher frequency of macrospermatids, loss of muscle mass and hemolymph amount as well as a low number of dividing cells and survival reduction. All these phenotypes are very likely due to the chromatin condensation disruption observed for almost all kinds of chromatin.
Collapse
|
31
|
Abstract
Genomic instability, which occurs through both genetic mechanisms (underlying inheritable phenotypic variations caused by DNA sequence-dependent alterations, such as mutation, deletion, insertion, inversion, translocation, and chromosomal aneuploidy) and epigenomic aberrations (underlying inheritable phenotypic variations caused by DNA sequence-independent alterations caused by a change of chromatin structure, such as DNA methylation and histone modifications), is known to promote tumorigenesis and tumor progression. Mechanisms involve both genomic instability and epigenomic aberrations that lose or gain the function of genes that impinge on tumor suppression/prevention or oncogenesis. Growing evidence points to an epigenome-wide disruption that involves large-scale DNA hypomethylation but specific hypermethylation of tumor suppressor genes, large blocks of aberrant histone modifications, and abnormal miRNA expression profile. Emerging molecular details regarding the modulation of these epigenetic events in cancer are used to illustrate the alterations of epigenetic molecules, and their consequent malfunctions could contribute to cancer biology. More recently, intriguing evidence supporting that genetic and epigenetic mechanisms are not separate events in cancer has been emerging; they intertwine and take advantage of each other during tumorigenesis. In addition, we discuss the collusion between epigenetics and genetics mediated by heterochromatin protein 1, a major component of heterochromatin, in order to maintain genome integrity.
Collapse
Affiliation(s)
- Jae Duk Choi
- Department of Life Science, College of Natural Sciences, Ajou University, Suwon 443-749, Korea
| | - Jong-Soo Lee
- Department of Life Science, College of Natural Sciences, Ajou University, Suwon 443-749, Korea
| |
Collapse
|
32
|
Abstract
The canonical JAK-STAT signaling pathway transmits signals from the cell membrane to the nucleus, to regulate transcription of particular genes involved in development and many other physiological processes. It has been shown in Drosophila that JAK and STAT also function in a non-canonical mode, to regulate heterochromatin. This review discusses the non-canonical functioning of JAK and STAT, and its effects on biological processes. Decreased levels of activated JAK and increased levels of unphosphorylated STAT generate higher levels of heterochromatin. These higher heterochromatin levels result in suppression of hematopoietic tumor-like masses, increased resistance to DNA damage, and longer lifespan.
Collapse
Affiliation(s)
- Louise Silver-Morse
- Department of Medicine; University of California San Diego; La Jolla, CA USA
| | | |
Collapse
|
33
|
Zeng A, Li YQ, Wang C, Han XS, Li G, Wang JY, Li DS, Qin YW, Shi Y, Brewer G, Jing Q. Heterochromatin protein 1 promotes self-renewal and triggers regenerative proliferation in adult stem cells. ACTA ACUST UNITED AC 2013; 201:409-25. [PMID: 23629965 PMCID: PMC3639387 DOI: 10.1083/jcb.201207172] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Adult stem cells (ASCs) capable of self-renewal and differentiation confer the potential of tissues to regenerate damaged parts. Epigenetic regulation is essential for driving cell fate decisions by rapidly and reversibly modulating gene expression programs. However, it remains unclear how epigenetic factors elicit ASC-driven regeneration. In this paper, we report that an RNA interference screen against 205 chromatin regulators identified 12 proteins essential for ASC function and regeneration in planarians. Surprisingly, the HP1-like protein SMED-HP1-1 (HP1-1) specifically marked self-renewing, pluripotent ASCs, and HP1-1 depletion abrogated self-renewal and promoted differentiation. Upon injury, HP1-1 expression increased and elicited increased ASC expression of Mcm5 through functional association with the FACT (facilitates chromatin transcription) complex, which consequently triggered proliferation of ASCs and initiated blastema formation. Our observations uncover an epigenetic network underlying ASC regulation in planarians and reveal that an HP1 protein is a key chromatin factor controlling stem cell function. These results provide important insights into how epigenetic mechanisms orchestrate stem cell responses during tissue regeneration.
Collapse
Affiliation(s)
- An Zeng
- Key Laboratory of Stem Cell Biology, Institute of Health Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences and Shanghai Jiao-Tong University School of Medicine, 200025 Shanghai, China
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
34
|
Lee DH, Li Y, Shin D, Yi SA, Bang S, Park EK, Han J, Kwon SH. DNA microarray profiling of genes differentially regulated by three heterochromatin protein 1 (HP1) homologs in Drosophila. Biochem Biophys Res Commun 2013; 434:820-8. [DOI: 10.1016/j.bbrc.2013.04.020] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2013] [Accepted: 04/13/2013] [Indexed: 01/24/2023]
|
35
|
Abstract
The DNA damage response (DDR) involves both the control of DNA damage repair and signaling to cell cycle checkpoints. Therefore, unraveling the underlying mechanisms of the DDR is important for understanding tumor suppression and cellular resistance to clastogenic cancer therapeutics. Because the DDR is likely to be influenced by chromatin regulation at the sites of DNA damage, we investigated the role of heterochromatin protein 1 (HP1) during the DDR process. We monitored double-strand breaks (DSBs) using the γH2AX foci marker and found that depleting cells of HP1 caused genotoxic stress, a delay in the repair of DSBs and elevated levels of apoptosis after irradiation. Furthermore, we found that these defects in repair were associated with impaired BRCA1 function. Depleting HP1 reduced recruitment of BRCA1 to DSBs and caused defects in two BRCA1-mediated DDR events: (i) the homologous recombination repair pathway and (ii) the arrest of cell cycle at the G2/M checkpoint. In contrast, depleting HP1 from cells did not affect the non-homologous end-joining (NHEJ) pathway: instead it elevated the recruitment of the 53BP1 NHEJ factor to DSBs. Notably, all three subtypes of HP1 seemed to be almost equally important for these DDR functions. We suggest that the dynamic interaction of HP1 with chromatin and other DDR factors could determine DNA repair choice and cell fate after DNA damage. We also suggest that compromising HP1 expression could promote tumorigenesis by impairing the function of the BRCA1 tumor suppressor.
Collapse
Affiliation(s)
- Young-Ho Lee
- Department of Molecular Pharmacology, Beckman Research Institute, City of Hope, Duarte, CA 91010, USA
| | | | | | | | | |
Collapse
|
36
|
Lundberg LE, Stenberg P, Larsson J. HP1a, Su(var)3-9, SETDB1 and POF stimulate or repress gene expression depending on genomic position, gene length and expression pattern in Drosophila melanogaster. Nucleic Acids Res 2013; 41:4481-94. [PMID: 23476027 PMCID: PMC3632140 DOI: 10.1093/nar/gkt158] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Heterochromatin protein 1a (HP1a) is a chromatin-associated protein important for the formation and maintenance of heterochromatin. In Drosophila, the two histone methyltransferases SETDB1 and Su(var)3-9 mediate H3K9 methylation marks that initiates the establishment and spreading of HP1a-enriched chromatin. Although HP1a is generally regarded as a factor that represses gene transcription, several reports have linked HP1a binding to active genes, and in some cases, it has been shown to stimulate transcriptional activity. To clarify the function of HP1a in transcription regulation and its association with Su(var)3-9, SETDB1 and the chromosome 4-specific protein POF, we conducted genome-wide expression studies and combined the results with available binding data in Drosophila melanogaster. The results suggest that HP1a, SETDB1 and Su(var)3-9 repress genes on chromosome 4, where non-ubiquitously expressed genes are preferentially targeted, and stimulate genes in pericentromeric regions. Further, we showed that on chromosome 4, Su(var)3-9, SETDB1 and HP1a target the same genes. In addition, we found that transposons are repressed by HP1a and Su(var)3-9 and that the binding level and expression effects of HP1a are affected by gene length. Our results indicate that genes have adapted to be properly expressed in their local chromatin environment.
Collapse
Affiliation(s)
- Lina E Lundberg
- Department of Molecular Biology, Umeå University, SE-90187 Umeå, Sweden
| | | | | |
Collapse
|
37
|
Lin CH, Paulson A, Abmayr SM, Workman JL. HP1a targets the Drosophila KDM4A demethylase to a subset of heterochromatic genes to regulate H3K36me3 levels. PLoS One 2012; 7:e39758. [PMID: 22761891 PMCID: PMC3384587 DOI: 10.1371/journal.pone.0039758] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2012] [Accepted: 05/31/2012] [Indexed: 12/12/2022] Open
Abstract
The KDM4 subfamily of JmjC domain-containing demethylases mediates demethylation of histone H3K36me3/me2 and H3K9me3/me2. Several studies have shown that human and yeast KDM4 proteins bind to specific gene promoters and regulate gene expression. However, the genome-wide distribution of KDM4 proteins and the mechanism of genomic-targeting remain elusive. We have previously identified Drosophila KDM4A (dKDM4A) as a histone H3K36me3 demethylase that directly interacts with HP1a. Here, we performed H3K36me3 ChIP-chip analysis in wild type and dkdm4a mutant embryos to identify genes regulated by dKDM4A demethylase activity in vivo. A subset of heterochromatic genes that show increased H3K36me3 levels in dkdm4a mutant embryos overlap with HP1a target genes. More importantly, binding to HP1a is required for dKDM4A-mediated H3K36me3 demethylation at a subset of heterochromatic genes. Collectively, these results show that HP1a functions to target the H3K36 demethylase dKDM4A to heterochromatic genes in Drosophila.
Collapse
Affiliation(s)
- Chia-Hui Lin
- Stowers Institute for Medical Research, Kansas City, Missouri, United States of America
| | - Ariel Paulson
- Stowers Institute for Medical Research, Kansas City, Missouri, United States of America
| | - Susan M. Abmayr
- Stowers Institute for Medical Research, Kansas City, Missouri, United States of America
- Department of Anatomy and Cell Biology, University of Kansas Medical Center, Kansas City, Kansas, United States of America
| | - Jerry L. Workman
- Stowers Institute for Medical Research, Kansas City, Missouri, United States of America
- * E-mail:
| |
Collapse
|
38
|
Salvany L, Requena D, Azpiazu N. Functional association between eyegone and HP1a mediates wingless transcriptional repression during development. Mol Cell Biol 2012; 32:2407-15. [PMID: 22547675 DOI: 10.1128/MCB.06311-11] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The eyegone (eyg) gene encodes Eyg, a transcription factor of the Pax family with multiple roles during Drosophila development. Although Eyg has been shown to act as a repressor, nothing is known about the mechanism by which it represses its target genes. Here, we show that Eyg forms a protein complex with heterochromatin protein 1a (HP1a). Both proteins bind to the same chromatin regions on polytene chromosomes and act cooperatively to suppress variegation and mediate gene silencing. In addition, Eyg binds to a wingless (wg) enhancer region, recruiting HP1a to assemble a closed, heterochromatin-like conformation that represses transcription of the wg gene. We describe here the evidence that suggests that Eyg, encoded by eyegone (eyg), represses wingless (wg) during eye development by association with HP1a. We show that Eyg forms a protein complex with HP1a and both proteins colocalize on salivary gland polytene chromosomes. Using position effect variegation (PEV) experiments, we demonstrated that eyg has a dose-dependent effect on heterochromatin gene silencing and identified a genetic interaction with HP1a in this process. We further demonstrated that HP1a binds to the same wg enhancer element as Eyg. DNase I sensitivity assays indicated that this enhancer region has a closed heterochromatin-like conformation, which becomes open in eyg mutants. In these mutants, much less HP1a binds to the wg enhancer region, as shown by ChIP experiments. Furthermore, as previously described for Eyg, a reduction in the amount of HP1a in the eye imaginal disc derepresses wg. Together, our results suggest a model in which Eyg specifically binds to the wg enhancer region, recruiting HP1a to that site. The recruitment of HP1a prevents transcription by favoring a closed, heterochromatin-like structure. Thus, for the first time, we show that HP1a plays a direct role in the repression of a developmentally regulated gene, wg, during Drosophila eye development.
Collapse
|
39
|
Rashmi RN, Eckes B, Glöckner G, Groth M, Neumann S, Gloy J, Sellin L, Walz G, Schneider M, Karakesisoglou I, Eichinger L, Noegel AA. The nuclear envelope protein Nesprin-2 has roles in cell proliferation and differentiation during wound healing. Nucleus 2012; 3:172-86. [PMID: 22198684 PMCID: PMC3383573 DOI: 10.4161/nucl.19090] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Nesprin-2, a type II transmembrane protein of the nuclear envelope, is a component of the LINC complex that connects the nuclear lamina with the actin cytoskeleton. To elucidate its physiological role we studied wound healing in Nesprin-2 Giant deficient mice and found that a loss of the protein affected wound healing particularly at later stages during fibroblast differentiation and keratinocyte proliferation leading to delayed wound closure. We identified altered expression and localization of transcription factors as one of the underlying mechanisms. Furthermore, the actin cytoskeleton which surrounds the nucleus was altered and keratinocyte migration was slowed down and focal adhesion formation enhanced. We also uncovered a new activity of Nesprin-2. When we probed for an interaction of Nesprin-2 Giant with chromatin we observed in ChIP Seq experiments an association of the protein with heterochromatic and centromeric DNA. Through this activity Nesprin-2 can affect the nuclear landscape and gene regulation. Our findings suggest functions for Nesprin-2 at the nuclear envelope (NE) in gene regulation and in regulation of the actin cytoskeleton which impact on wound healing.
Collapse
Affiliation(s)
- R N Rashmi
- Institute of Biochemistry I, Medical Faculty, University of Cologne, Cologne, Germany
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
40
|
Yin H, Sweeney S, Raha D, Snyder M, Lin H. A high-resolution whole-genome map of key chromatin modifications in the adult Drosophila melanogaster. PLoS Genet 2011; 7:e1002380. [PMID: 22194694 DOI: 10.1371/journal.pgen.1002380] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2010] [Accepted: 09/27/2011] [Indexed: 01/21/2023] Open
Abstract
Epigenetic research has been focused on cell-type-specific regulation; less is known about common features of epigenetic programming shared by diverse cell types within an organism. Here, we report a modified method for chromatin immunoprecipitation and deep sequencing (ChIP–Seq) and its use to construct a high-resolution map of the Drosophila melanogaster key histone marks, heterochromatin protein 1a (HP1a) and RNA polymerase II (polII). These factors are mapped at 50-bp resolution genome-wide and at 5-bp resolution for regulatory sequences of genes, which reveals fundamental features of chromatin modification landscape shared by major adult Drosophila cell types: the enrichment of both heterochromatic and euchromatic marks in transposons and repetitive sequences, the accumulation of HP1a at transcription start sites with stalled polII, the signatures of histone code and polII level/position around the transcriptional start sites that predict both the mRNA level and functionality of genes, and the enrichment of elongating polII within exons at splicing junctions. These features, likely conserved among diverse epigenomes, reveal general strategies for chromatin modifications. Just as a genome sequence map is indispensible to genetic studies, an epigenome map is crucial for epigenetic research. This is especially true for a sophisticated genetic model such as Drosophila melanogaster, where the wealth of information on genetics and developmental biology awaits systematic epigenetic interpretation on a whole-genome scale. In this manuscript, we report a high-resolution map of key chromatin modifications in the Drosophila genome constructed by the ChIP–Seq approach. This map is derived from all cell types in the adult Drosophila weighted by their natural abundance. It contains key histone marks, HP1a and RNA polymerase II, mapped at 50-bp resolution throughout the genome and at 5-bp resolution for regulatory sequences of genes. It reveals striking features of chromatin modification and transcriptional regulation shared by major adult Drosophila cell types. We anticipate that this map and the salient chromatin modification landscapes revealed by this map should have broad utility to the fields of epigenetics, developmental biology, and stem cell biology.
Collapse
|
41
|
Studencka M, Konzer A, Moneron G, Wenzel D, Opitz L, Salinas-Riester G, Bedet C, Krüger M, Hell SW, Wisniewski JR, Schmidt H, Palladino F, Schulze E, Jedrusik-Bode M. Novel roles of Caenorhabditis elegans heterochromatin protein HP1 and linker histone in the regulation of innate immune gene expression. Mol Cell Biol 2012; 32:251-65. [PMID: 22083954 DOI: 10.1128/MCB.05229-11] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Linker histone (H1) and heterochromatin protein 1 (HP1) are essential components of heterochromatin which contribute to the transcriptional repression of genes. It has been shown that the methylation mark of vertebrate histone H1 is specifically recognized by the chromodomain of HP1. However, the exact biological role of linker histone binding to HP1 has not been determined. Here, we investigate the function of the Caenorhabditis elegans H1 variant HIS-24 and the HP1-like proteins HPL-1 and HPL-2 in the cooperative transcriptional regulation of immune-relevant genes. We provide the first evidence that HPL-1 interacts with HIS-24 monomethylated at lysine 14 (HIS-24K14me1) and associates in vivo with promoters of genes involved in antimicrobial response. We also report an increase in overall cellular levels and alterations in the distribution of HIS-24K14me1 after infection with pathogenic bacteria. HIS-24K14me1 localization changes from being mostly nuclear to both nuclear and cytoplasmic in the intestinal cells of infected animals. Our results highlight an antimicrobial role of HIS-24K14me1 and suggest a functional link between epigenetic regulation by an HP1/H1 complex and the innate immune system in C. elegans.
Collapse
|
42
|
Abstract
Chromatin structure regulates the dynamics of the recognition and repair of DNA double strand breaks; open chromatin enhances the recruitment of DNA damage response factors, while compact chromatin is refractory to the assembly of radiation-induced repair foci. MU2, an orthologue of human MDC1, a scaffold for ionizing radiation-induced repair foci, is a widely distributed chromosomal protein in Drosophila melanogaster that moves to DNA repair foci after irradiation. Here we show using yeast 2 hybrid screens and co-immunoprecipitation that MU2 binds the chromoshadow domain of the heterochromatin protein HP1 in untreated cells. We asked what role HP1 plays in the formation of repair foci and cell cycle control in response to DNA damage. After irradiation repair foci form in heterochromatin but are shunted to the edge of heterochromatic regions an HP1-dependent manner, suggesting compartmentalized repair. Hydroxyurea-induced repair foci that form at collapsed replication forks, however, remain in the heterochromatic compartment. HP1a depletion in irradiated imaginal disc cells increases apoptosis and disrupts G2/M arrest. Further, cells irradiated in mitosis produced more and brighter repair foci than to cells irradiated during interphase. Thus, the interplay between MU2 and HP1a is dynamic and may be different in euchromatin and heterochromatin during DNA break recognition and repair.
Collapse
Affiliation(s)
- Raghuvar Dronamraju
- Laboratory of Molecular Genetics, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina, United States of America
| | - James M. Mason
- Laboratory of Molecular Genetics, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina, United States of America
- * E-mail:
| |
Collapse
|
43
|
Kwon SH, Workman JL. The changing faces of HP1: From heterochromatin formation and gene silencing to euchromatic gene expression: HP1 acts as a positive regulator of transcription. Bioessays 2011; 33:280-9. [PMID: 21271610 DOI: 10.1002/bies.201000138] [Citation(s) in RCA: 120] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Heterochromatin protein 1 (HP1) is a positive regulator of active transcription in euchromatin. HP1 was first identified in Drosophila melanogaster as a major component of heterochromatin. Most eukaryotes have at least three isoforms of HP1, which are conserved in overall structure but localize differentially to heterochromatin and euchromatin. Although initial studies revealed a key role for HP1 in heterochromatin formation and gene silencing, recent progress has shed light on additional roles for HP1 in processes such as euchromatic gene expression. Recent studies have highlighted the importance of HP1-mediated gene regulation in euchromatin. Here, we focus on recent advances in understanding the role of HP1 in active transcription in euchromatin and how modification and localization of HP1 can regulate distinct functions for this protein in different contexts.
Collapse
Affiliation(s)
- So Hee Kwon
- Stowers Institute for Medical Research, Kansas City, MO, USA
| | | |
Collapse
|
44
|
Kwon SH, Florens L, Swanson SK, Washburn MP, Abmayr SM, Workman JL. Heterochromatin protein 1 (HP1) connects the FACT histone chaperone complex to the phosphorylated CTD of RNA polymerase II. Genes Dev 2010; 24:2133-45. [PMID: 20889714 DOI: 10.1101/gad.1959110] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Heterochromatin protein 1 (HP1) is well known as a silencing protein found at pericentric heterochromatin. Most eukaryotes have at least three isoforms of HP1 that play differential roles in heterochromatin and euchromatin. In addition to its role in heterochromatin, HP1 proteins have been shown to function in transcription elongation. To gain insights into the transcription functions of HP1, we sought to identify novel HP1-interacting proteins. Biochemical and proteomic approaches revealed that HP1 interacts with the histone chaperone complex FACT (facilitates chromatin transcription). HP1c interacts with the SSRP1 (structure-specific recognition protein 1) subunit and the intact FACT complex. Moreover, HP1c guides the recruitment of FACT to active genes and links FACT to active forms of RNA polymerase II. The absence of HP1c partially impairs the recruitment of FACT into heat-shock loci and causes a defect in heat-shock gene expression. Thus, HP1c functions to recruit the FACT complex to RNA polymerase II.
Collapse
Affiliation(s)
- So Hee Kwon
- Stowers Institute for Medical Research, Kansas City, Missouri 64110, USA
| | | | | | | | | | | |
Collapse
|
45
|
Zhang D, Wang D, Sun F. Drosophila melanogaster heterochromatin protein HP1b plays important roles in transcriptional activation and development. Chromosoma 2011; 120:97-108. [PMID: 20857302 DOI: 10.1007/s00412-010-0294-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2010] [Revised: 09/05/2010] [Accepted: 09/06/2010] [Indexed: 12/30/2022]
Abstract
The condensed heterochromatic domains are known to be associated with transcriptional repression and cell differentiation. Here, we investigate the function of heterochromatin protein HP1b, a member of the HP1 family in Drosophila melanogaster, in transcription and development. Both knockdown and overexpression of HP1b resulted in partial lethality, indicating that HP1b is essential for the normal development. In contrast to the positive role of HP1a in heterochromatin formation, overexpression of HP1b decondensed the pericentromeric heterochromatin and reduced the association of HP1a and H3K9me2 with it, both known markers of pericentric heterochromatin. Interestingly, the structure of the heterochromatic fourth chromosome appeared not to be affected. Further experiments showed that the presence of HP1a partially rescued the lethality caused by HP1b overexpression in males, and it fully rescued the lethality in females. Consistent with this observation, the defective transcription of heterochromatic genes was also partially restored in the presence of HP1a. Overall, this study argues that HP1b counteracts HP1a function both in heterochromatin formation and in the transcriptional regulation of euchromatic genes.
Collapse
|
46
|
Bulchand S, Menon SD, George SE, Chia W. Muscle wasted: a novel component of the Drosophila histone locus body required for muscle integrity. J Cell Sci 2010; 123:2697-707. [DOI: 10.1242/jcs.063172] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Skeletal muscles arise by cellular differentiation and regulated gene expression. Terminal differentiation programmes such as muscle growth, extension and attachment to the epidermis, lead to maturation of the muscles. These events require changes in chromatin organization as genes are differentially regulated. Here, we identify and characterise muscle wasted (mute), a novel component of the Drosophila histone locus body (HLB). We demonstrate that a mutation in mute leads to severe loss of muscle mass and an increase in levels of normal histone transcripts. Importantly, Drosophila Myocyte enhancer factor 2 (Mef2), a central myogenic differentiation factor, and how, an RNA binding protein required for muscle and tendon cell differentiation, are downregulated. Mef2 targets are, in turn, misregulated. Notably, the degenerating muscles in mute mutants show aberrant localisation of heterochromatin protein 1 (HP1). We further show a genetic interaction between mute and the Stem-loop binding protein (Slbp) and a loss of muscle striations in Lsm11 mutants. These data demonstrate a novel role of HLB components and histone processing factors in the maintenance of muscle integrity. We speculate that mute regulates terminal muscle differentiation possibly through heterochromatic reorganisation.
Collapse
Affiliation(s)
- Sarada Bulchand
- Temasek Lifesciences Laboratory, National University of Singapore, 1 Research Link, 117604, Singapore
| | - Sree Devi Menon
- Temasek Lifesciences Laboratory, National University of Singapore, 1 Research Link, 117604, Singapore
| | - Simi Elizabeth George
- Temasek Lifesciences Laboratory, National University of Singapore, 1 Research Link, 117604, Singapore
| | - William Chia
- Temasek Lifesciences Laboratory, National University of Singapore, 1 Research Link, 117604, Singapore
| |
Collapse
|
47
|
Heffernan C, Whiley PAF, Milionis A, Verma PJ, Holland MK, Jans DA, D'Cruz NT. Lineage-specific expression of heterochromatin protein 1gamma in post-compaction, in vitro-produced bovine embryos. Reprod Fertil Dev 2010; 22:1022-31. [PMID: 20591336 DOI: 10.1071/rd09265] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2009] [Accepted: 02/01/2010] [Indexed: 01/27/2023] Open
Abstract
Heterochromatin protein 1gamma (HP1gamma) is a highly conserved regulator of euchromatic and heterochromatic gene expression. Mammalian HP1gamma is essential for both successful preimplantation embryo development and maintenance of pluripotency in embryonic stem cells in vitro. Here, we describe HP1gamma protein localisation in matured (MII) bovine oocytes and IVF preimplantation embryos at defined developmental stages. HP1gamma is expressed in post-compaction embryos in a highly lineage-specific pattern. In embryonic stages preceding the maternal to embryonic transition (MET), HP1gamma protein was primarily cytoplasmic, whereas in 8-16-cell embryos (post MET), HP1gamma was primarily nuclear. Lineage-specific patterns of HP1gamma protein localisation become evident from compaction, being restricted to peripheral, extraembryonic cells at the morula and blastocyst stages (Days 7-9). Surprisingly, we detected HP1gamma mRNA in both embryonic and extraembryonic cells in blastocysts by fluorescence in situ hybridisation. In trophectoderm cells, HP1gamma protein was localised in specific patterns at the mitotic and interphase stages of the cell cycle. These results demonstrate lineage- and cell cycle-specific patterns of HP1gamma protein localisation in the post-compaction, preimplantation bovine embryo and raise interesting questions about the role of HP1gamma in early embryo development.
Collapse
Affiliation(s)
- Corey Heffernan
- Monash Institute of Medical Research, Monash University, Clayton, Vic., Australia
| | | | | | | | | | | | | |
Collapse
|
48
|
De Koning L, Savignoni A, Boumendil C, Rehman H, Asselain B, Sastre-Garau X, Almouzni G. Heterochromatin protein 1alpha: a hallmark of cell proliferation relevant to clinical oncology. EMBO Mol Med 2010; 1:178-91. [PMID: 20049717 PMCID: PMC3378125 DOI: 10.1002/emmm.200900022] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Mammalian cells contain three closely related heterochromatin protein 1 (HP1) isoforms, HP1α, β and γ, which, by analogy to their unique counterpart in Schizosaccharomyces pombe, have been implicated in gene silencing, genome stability and chromosome segregation. However, the individual importance of each isoform during normal cell cycle and disease has remained an unresolved issue. Here, we reveal that HP1α shows a proliferation-dependent regulation, which neither HP1β nor γ display. During transient cell cycle exit, the HP1α mRNA and protein levels diminish. Transient depletion of HP1α, but not HP1β or γ, in tumoural and primary human cells leads to defects in chromosome segregation. Notably, analysis of an annotated collection of samples derived from carcinomas reveals an overexpression of HP1α mRNA and protein, which correlates with clinical data and disease outcome. Our results unveil a specific expression pattern for the HP1α isoform, suggesting a unique function related to cell division and tumour growth. The overexpression of HP1α constitutes a new example of a potential epigenetic contribution to tumourigenesis that is of clinical interest for cancer prognosis.
Collapse
Affiliation(s)
- Leanne De Koning
- Laboratory of Nuclear Dynamics and Genome Plasticity (UMR218), Institut Curie/CNRS/UPMC, 26 Rue d'Ulm, 75248 Paris Cedex 05, France
| | | | | | | | | | | | | |
Collapse
|
49
|
Piacentini L, Fanti L, Negri R, Del Vescovo V, Fatica A, Altieri F, Pimpinelli S. Heterochromatin protein 1 (HP1a) positively regulates euchromatic gene expression through RNA transcript association and interaction with hnRNPs in Drosophila. PLoS Genet 2009; 5:e1000670. [PMID: 19798443 DOI: 10.1371/journal.pgen.1000670] [Citation(s) in RCA: 121] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2009] [Accepted: 09/02/2009] [Indexed: 11/19/2022] Open
Abstract
Heterochromatin Protein 1 (HP1a) is a well-known conserved protein involved in heterochromatin formation and gene silencing in different species including humans. A general model has been proposed for heterochromatin formation and epigenetic gene silencing in different species that implies an essential role for HP1a. According to the model, histone methyltransferase enzymes (HMTases) methylate the histone H3 at lysine 9 (H3K9me), creating selective binding sites for itself and the chromodomain of HP1a. This complex is thought to form a higher order chromatin state that represses gene activity. It has also been found that HP1a plays a role in telomere capping. Surprisingly, recent studies have shown that HP1a is present at many euchromatic sites along polytene chromosomes of Drosophila melanogaster, including the developmental and heat-shock-induced puffs, and that this protein can be removed from these sites by in vivo RNase treatment, thus suggesting an association of HP1a with the transcripts of many active genes. To test this suggestion, we performed an extensive screening by RIP-chip assay (RNA–immunoprecipitation on microarrays), and we found that HP1a is associated with transcripts of more than one hundred euchromatic genes. An expression analysis in HP1a mutants shows that HP1a is required for positive regulation of these genes. Cytogenetic and molecular assays show that HP1a also interacts with the well known proteins DDP1, HRB87F, and PEP, which belong to different classes of heterogeneous nuclear ribonucleoproteins (hnRNPs) involved in RNA processing. Surprisingly, we found that all these hnRNP proteins also bind heterochromatin and are dominant suppressors of position effect variegation. Together, our data show novel and unexpected functions for HP1a and hnRNPs proteins. All these proteins are in fact involved both in RNA transcript processing and in heterochromatin formation. This suggests that, in general, similar epigenetic mechanisms have a significant role on both RNA and heterochromatin metabolisms. Heterochromatin Protein 1 (HP1a) is a very well known prototype protein of a general model for heterochromatin formation and epigenetic gene silencing in different species including humans. Here, we report our experiments showing that HP1a is also required for the positive regulation of more than one hundred euchromatic genes by its association with the corresponding RNA transcripts and by its interaction with heterogeneous nuclear ribonucleoproteins (hnRNPs) belonging to different classes. Importantly, we also found that all the tested hnRNP proteins bind to the heterochromatin and are dominant suppressors of position effect variegation, thus suggesting they also have a role in heterochromatin organization. Taken together, our data show novel and important functions, not only for HP1a, but also for hnRNPs, which were previously believed to participate only in RNA processing. These results shed new light on the epigenetic mechanisms of gene silencing and gene expression. They also establish a link between RNA transcript metabolism and heterochromatin formation and change several aspects of the canonical views about these apparently different processes.
Collapse
|
50
|
Serrano Á, Rodríguez-Corsino M, Losada A. Heterochromatin protein 1 (HP1) proteins do not drive pericentromeric cohesin enrichment in human cells. PLoS One 2009; 4:e5118. [PMID: 19352502 PMCID: PMC2662427 DOI: 10.1371/journal.pone.0005118] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2008] [Accepted: 03/09/2009] [Indexed: 01/02/2023] Open
Abstract
Sister chromatid cohesion mediated by cohesin is essential for accurate chromosome segregation. Classical studies suggest that heterochromatin promotes cohesion, but whether this happens through regulation of cohesin remains to be determined. Heterochromatin protein 1 (HP1) is a major component of heterochromatin. In fission yeast, the HP1 homologue Swi6 interacts with cohesin and is required for proper targeting and/or stabilization of cohesin at the centromeric region. To test whether this pathway is conserved in human cells, we have examined the behavior of cohesin in cells in which the levels of HP1 alpha, beta or gamma (the three HP1 proteins present in mammalian organisms) have been reduced by siRNA. We have also studied the consequences of treating human cells with drugs that change the histone modification profile of heterochromatin and thereby affect HP1 localization. Our results show no evidence for a requirement of HP1 proteins for either loading of bulk cohesin onto chromatin in interphase or retention of cohesin at pericentric heterochromatin in mitosis. However, depletion of HP1gamma leads to defects in mitotic progression.
Collapse
Affiliation(s)
- Ángel Serrano
- Chromosome Dynamics Group, Molecular Oncology Programme, Spanish National Cancer Research Centre (CNIO), Madrid, Spain
| | - Miriam Rodríguez-Corsino
- Chromosome Dynamics Group, Molecular Oncology Programme, Spanish National Cancer Research Centre (CNIO), Madrid, Spain
| | - Ana Losada
- Chromosome Dynamics Group, Molecular Oncology Programme, Spanish National Cancer Research Centre (CNIO), Madrid, Spain
| |
Collapse
|