1
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Ames A, Seman M, Larkin A, Raiymbek G, Chen Z, Levashkevich A, Kim B, Biteen JS, Ragunathan K. Epigenetic memory is governed by an effector recruitment specificity toggle in Heterochromatin Protein 1. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.11.28.569027. [PMID: 38077059 PMCID: PMC10705379 DOI: 10.1101/2023.11.28.569027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/20/2023]
Abstract
HP1 proteins are essential for establishing and maintaining transcriptionally silent heterochromatin. They dimerize, forming a binding interface to recruit diverse chromatin-associated factors. HP1 proteins are specialized and rapidly evolve, but the extent of variation required to achieve functional specialization is unknown. To investigate how changes in amino acid sequence impacts epigenetic inheritance, we performed a targeted mutagenesis screen of the S. pombe HP1 homolog, Swi6. Substitutions within an auxiliary surface adjacent to the HP1 dimerization interface produced Swi6 variants with divergent maintenance properties. Remarkably, substitutions at a single amino acid position led to the persistent gain or loss of epigenetic inheritance. These substitutions increased Swi6 chromatin occupancy in vivo and altered Swi6-protein interactions that reprogram H3K9me maintenance. We show that relatively minor changes in Swi6 amino acid composition can lead to profound changes in epigenetic inheritance which provides a redundant mechanism to evolve novel effector specificity. .
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2
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Ding Z, Peng L, Zeng J, Yuan K, Tang Y, Yi Q. Functions of HP1 in preventing chromosomal instability. Cell Biochem Funct 2024; 42:e4017. [PMID: 38603595 DOI: 10.1002/cbf.4017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Revised: 04/03/2024] [Accepted: 04/03/2024] [Indexed: 04/13/2024]
Abstract
Chromosomal instability (CIN), caused by errors in the segregation of chromosomes during mitosis, is a hallmark of many types of cancer. The fidelity of chromosome segregation is governed by a sophisticated cellular signaling network, one crucial orchestrator of which is Heterochromatin protein 1 (HP1). HP1 dynamically localizes to distinct sites at various stages of mitosis, where it regulates key mitotic events ranging from chromosome-microtubule attachment to sister chromatid cohesion to cytokinesis. Our evolving comprehension of HP1's multifaceted role has positioned it as a central protein in the orchestration of mitotic processes.
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Affiliation(s)
- Zexian Ding
- Key Laboratory of Model Animals and Stem Cell Biology in Hunan Province, Hunan Normal University School of Medicine, Changsha, Hunan, China
| | - Lei Peng
- Key Laboratory of Model Animals and Stem Cell Biology in Hunan Province, Hunan Normal University School of Medicine, Changsha, Hunan, China
| | - Jinghua Zeng
- Key Laboratory of Model Animals and Stem Cell Biology in Hunan Province, Hunan Normal University School of Medicine, Changsha, Hunan, China
| | - Kejia Yuan
- Key Laboratory of Model Animals and Stem Cell Biology in Hunan Province, Hunan Normal University School of Medicine, Changsha, Hunan, China
| | - Yan Tang
- Key Laboratory of Model Animals and Stem Cell Biology in Hunan Province, Hunan Normal University School of Medicine, Changsha, Hunan, China
| | - Qi Yi
- Key Laboratory of Model Animals and Stem Cell Biology in Hunan Province, Hunan Normal University School of Medicine, Changsha, Hunan, China
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3
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Tortora MMC, Brennan LD, Karpen G, Jost D. HP1-driven phase separation recapitulates the thermodynamics and kinetics of heterochromatin condensate formation. Proc Natl Acad Sci U S A 2023; 120:e2211855120. [PMID: 37549295 PMCID: PMC10438847 DOI: 10.1073/pnas.2211855120] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Accepted: 06/28/2023] [Indexed: 08/09/2023] Open
Abstract
The spatial segregation of pericentromeric heterochromatin (PCH) into distinct, membrane-less nuclear compartments involves the binding of Heterochromatin Protein 1 (HP1) to H3K9me2/3-rich genomic regions. While HP1 exhibits liquid-liquid phase separation properties in vitro, its mechanistic impact on the structure and dynamics of PCH condensate formation in vivo remains largely unresolved. Here, using a minimal theoretical framework, we systematically investigate the mutual coupling between self-interacting HP1-like molecules and the chromatin polymer. We reveal that the specific affinity of HP1 for H3K9me2/3 loci facilitates coacervation in nucleo and promotes the formation of stable PCH condensates at HP1 levels far below the concentration required to observe phase separation in purified protein assays in vitro. These heterotypic HP1-chromatin interactions give rise to a strong dependence of the nucleoplasmic HP1 density on HP1-H3K9me2/3 stoichiometry, consistent with the thermodynamics of multicomponent phase separation. The dynamical cross talk between HP1 and the viscoelastic chromatin scaffold also leads to anomalously slow equilibration kinetics, which strongly depend on the genomic distribution of H3K9me2/3 domains and result in the coexistence of multiple long-lived, microphase-separated PCH compartments. The morphology of these complex coacervates is further found to be governed by the dynamic establishment of the underlying H3K9me2/3 landscape, which may drive their increasingly abnormal, aspherical shapes during cell development. These findings compare favorably to 4D microscopy measurements of HP1 condensate formation in live Drosophila embryos and suggest a general quantitative model of PCH formation based on the interplay between HP1-based phase separation and chromatin polymer mechanics.
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Affiliation(s)
- Maxime M. C. Tortora
- Laboratoire de Biologie et Modélisation de la Cellule, École Normale Supérieure de Lyon, CNRS, UMR5239, Inserm U1293, Université Claude Bernard Lyon 1, 69007Lyon, France
| | - Lucy D. Brennan
- Department of Molecular and Cell Biology, University of California, Berkeley, CA94720
| | - Gary Karpen
- Department of Molecular and Cell Biology, University of California, Berkeley, CA94720
- Department of BioEngineering and BioMedical Sciences, Lawrence Berkeley National Laboratory, Berkeley, CA94720
| | - Daniel Jost
- Laboratoire de Biologie et Modélisation de la Cellule, École Normale Supérieure de Lyon, CNRS, UMR5239, Inserm U1293, Université Claude Bernard Lyon 1, 69007Lyon, France
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4
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Yin L, Han Z, Feng M, Wang J, Xie Z, Yu W, Fu X, Shen N, Wang X, Duan A, Zhang Y, Ma J. Chimeric transcripts observed in non-canonical FGFR2 fusions with partner genes' breakpoint located in intergenic region in intrahepatic cholangiocarcinoma. Cancer Genet 2022; 266-267:39-43. [PMID: 35749865 DOI: 10.1016/j.cancergen.2022.06.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Revised: 05/29/2022] [Accepted: 06/11/2022] [Indexed: 11/28/2022]
Abstract
Intrahepatic cholangiocarcinoma (ICC) is a fatal bile duct cancer with dismal prognosis and limited therapeutic options. FGFR family fusion have been identified in many diseases, and FGFR2 fusion is a validated oncogenic driver in ICC. At present, a variety of fusion forms have been reported, including gene-gene, gene-intergenic, and intergenic-intergenic fusion. Here, by performing RNA- and DNA-sequencing analysis, FGFR2 fusions were found in 10.1% of ICC, including 4 gene-intergenic fusions. We confirmed that the non-canonical rearrangements can generate chimeric transcripts, and used conventional splicing mechanism to explain the event. Our study provides possible target therapy for these 4 patients and possibility analysis scheme for similar situation.
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Affiliation(s)
- Lei Yin
- 2nd Department of Biliary Truct Surgery, Eastern Hepatobiliary surgery hospital, 225#Changhai Road, Shanghai, China
| | - Zhijun Han
- Department of Bioinformatics, 3D Medicines Inc., Shanghai, China
| | - Meilin Feng
- Department of Data System, 3D Medicines Inc, Shanghai, China
| | - Jie Wang
- Department of Bioinformatics, 3D Medicines Inc., Shanghai, China
| | - Zhenghua Xie
- Department of Research and Development, 3D Medicines Inc, Shanghai, China
| | - Wenlong Yu
- 2nd Department of Biliary Truct Surgery, Eastern Hepatobiliary surgery hospital, 225#Changhai Road, Shanghai, China
| | - Xiaohui Fu
- 2nd Department of Biliary Truct Surgery, Eastern Hepatobiliary surgery hospital, 225#Changhai Road, Shanghai, China
| | - Ningjia Shen
- 2nd Department of Biliary Truct Surgery, Eastern Hepatobiliary surgery hospital, 225#Changhai Road, Shanghai, China
| | - Xiang Wang
- 2nd Department of Biliary Truct Surgery, Eastern Hepatobiliary surgery hospital, 225#Changhai Road, Shanghai, China
| | - Anqi Duan
- 2nd Department of Biliary Truct Surgery, Eastern Hepatobiliary surgery hospital, 225#Changhai Road, Shanghai, China
| | - Yongjie Zhang
- 2nd Department of Biliary Truct Surgery, Eastern Hepatobiliary surgery hospital, 225#Changhai Road, Shanghai, China.
| | - Jing Ma
- Department of Data System, 3D Medicines Inc, Shanghai, China.
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5
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Lamb KN, Dishman SN, Waybright JM, Engelberg IA, Rectenwald JM, Norris-Drouin JL, Cholensky SH, Pearce KH, James LI, Frye SV. Discovery of Potent Peptidomimetic Antagonists for Heterochromatin Protein 1 Family Proteins. ACS OMEGA 2022; 7:716-732. [PMID: 35036738 PMCID: PMC8757366 DOI: 10.1021/acsomega.1c05381] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Accepted: 12/07/2021] [Indexed: 06/14/2023]
Abstract
The heterochromatin protein 1 (HP1) sub-family of CBX chromodomains are responsible for the recognition of histone H3 lysine 9 tri-methyl (H3K9me3)-marked nucleosomal substrates through binding of the N-terminal chromodomain. These HP1 proteins, namely, CBX1 (HP1β), CBX3 (HP1γ), and CBX5 (HP1α), are commonly associated with regions of pericentric heterochromatin, but recent literature studies suggest that regulation by these proteins is likely more dynamic and includes other loci. Importantly, there are no chemical tools toward HP1 chromodomains to spatiotemporally explore the effects of HP1-mediated processes, underscoring the need for novel HP1 chemical probes. Here, we report the discovery of HP1 targeting peptidomimetic compounds, UNC7047 and UNC7560, and a biotinylated derivative tool compound, UNC7565. These compounds represent an important milestone, as they possess nanomolar affinity for the CBX5 chromodomain by isothermal titration calorimetry (ITC) and bind HP1-containing complexes in cell lysates. These chemical tools provide a starting point for further optimization and the study of CBX5-mediated processes.
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Affiliation(s)
- Kelsey N. Lamb
- Center
for Integrative Chemical Biology and Drug Discovery, Division of Chemical
Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Sarah N. Dishman
- Center
for Integrative Chemical Biology and Drug Discovery, Division of Chemical
Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Jarod M. Waybright
- Center
for Integrative Chemical Biology and Drug Discovery, Division of Chemical
Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Isabelle A. Engelberg
- Center
for Integrative Chemical Biology and Drug Discovery, Division of Chemical
Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Justin M. Rectenwald
- Center
for Integrative Chemical Biology and Drug Discovery, Division of Chemical
Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Jacqueline L. Norris-Drouin
- Center
for Integrative Chemical Biology and Drug Discovery, Division of Chemical
Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Stephanie H. Cholensky
- Center
for Integrative Chemical Biology and Drug Discovery, Division of Chemical
Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Kenneth H. Pearce
- Center
for Integrative Chemical Biology and Drug Discovery, Division of Chemical
Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Lindsey I. James
- Center
for Integrative Chemical Biology and Drug Discovery, Division of Chemical
Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Stephen V. Frye
- Center
for Integrative Chemical Biology and Drug Discovery, Division of Chemical
Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
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6
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Meyer-Nava S, Nieto-Caballero VE, Zurita M, Valadez-Graham V. Insights into HP1a-Chromatin Interactions. Cells 2020; 9:E1866. [PMID: 32784937 PMCID: PMC7465937 DOI: 10.3390/cells9081866] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Revised: 07/18/2020] [Accepted: 07/21/2020] [Indexed: 12/17/2022] Open
Abstract
Understanding the packaging of DNA into chromatin has become a crucial aspect in the study of gene regulatory mechanisms. Heterochromatin establishment and maintenance dynamics have emerged as some of the main features involved in genome stability, cellular development, and diseases. The most extensively studied heterochromatin protein is HP1a. This protein has two main domains, namely the chromoshadow and the chromodomain, separated by a hinge region. Over the years, several works have taken on the task of identifying HP1a partners using different strategies. In this review, we focus on describing these interactions and the possible complexes and subcomplexes associated with this critical protein. Characterization of these complexes will help us to clearly understand the implications of the interactions of HP1a in heterochromatin maintenance, heterochromatin dynamics, and heterochromatin's direct relationship to gene regulation and chromatin organization.
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Affiliation(s)
| | | | | | - Viviana Valadez-Graham
- Instituto de Biotecnología, Departamento de Genética del Desarrollo y Fisiología Molecular, Universidad Nacional Autónoma de México, Cuernavaca Morelos 62210, Mexico; (S.M.-N.); (V.E.N.-C.); (M.Z.)
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7
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Sanulli S, Gross JD, Narlikar GJ. Biophysical Properties of HP1-Mediated Heterochromatin. COLD SPRING HARBOR SYMPOSIA ON QUANTITATIVE BIOLOGY 2020; 84:217-225. [PMID: 32493764 PMCID: PMC9128075 DOI: 10.1101/sqb.2019.84.040360] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Heterochromatin is a classic context for studying the mechanisms of chromatin organization. At the core of a highly conserved type of heterochromatin is the complex formed between chromatin methylated on histone H3 lysine 9 and HP1 proteins. This type of heterochromatin plays central roles in gene repression, genome stability, and nuclear mechanics. Systematic studies over the last several decades have provided insight into the biophysical mechanisms by which the HP1-chromatin complex is formed. Here, we discuss these studies together with recent findings indicating a role for phase separation in heterochromatin organization and function. We suggest that the different functions of HP1-mediated heterochromatin may rely on the increasing diversity being uncovered in the biophysical properties of HP1-chromatin complexes.
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Affiliation(s)
- Serena Sanulli
- Department of Pharmaceutical Chemistry, University of California, San Francisco, California 94158, USA
| | - John D Gross
- Department of Pharmaceutical Chemistry, University of California, San Francisco, California 94158, USA
| | - Geeta J Narlikar
- Department of Biochemistry and Biophysics, University of California, San Francisco, California 94158, USA
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8
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Okamoto K, Tanaka Y, Ogasawara S, Obuse C, Nakayama JI, Yano H, Tsuneoka M. KDM2A-dependent reduction of rRNA transcription on glucose starvation requires HP1 in cells, including triple-negative breast cancer cells. Oncotarget 2019; 10:4743-4760. [PMID: 31413816 PMCID: PMC6677663 DOI: 10.18632/oncotarget.27092] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Accepted: 06/29/2019] [Indexed: 12/24/2022] Open
Abstract
Triple-negative breast cancer (TNBC) is very aggressive and lacks specific therapeutic targets. Ribosome RNAs (rRNAs) are central components of ribosomes and transcribed in nucleoli, and the level of rRNA transcription greatly affects ribosome production and cell proliferation. We have reported that an epigenetic protein, KDM2A, exists in nucleoli and reduces rRNA transcription on glucose starvation. However, the molecular mechanism is still unclear. The purpose of this study is to examine the KDM2A-dependent regulation mechanism of rRNA transcription. In this study, we turned our attention to the nucleolar accumulation of KDM2A. We found that KDM2A had multiple regions for its nucleolar localization, and one of the regions was directly bound by heterochromatin protein 1γ (HP1γ) using valine 801 in the LxVxL motif of KDM2A. A knockdown of HP1γ or a point mutation of valine 801 in KDM2A decreased the nucleolar accumulation of KDM2A, and suppressed the reduction of rRNA transcription on glucose starvation. These results uncovered a novel function of HP1γ: the regulation of rRNA transcription, and suggested that HP1γ stimulates the nucleolar accumulation of KDM2A to support the KDM2A-dependent regulation of rRNA transcription. HP1γ was expressed in cancer cells in all breast carcinoma tissues examined, including TNBC tissues. A knockdown of HP1γ in a TNBC cell line, MDA-MB-231 cells, reduced the nucleolar accumulation of KDM2A, and suppressed the reductions of rRNA transcription and cell proliferation on glucose starvation. These results suggest that the KDM2A-dependent regulation of rRNA transcription requires HP1γ, and thus may be applicable to the treatment of TNBC.
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Affiliation(s)
- Kengo Okamoto
- Laboratory of Molecular and Cellular Biology, Faculty of Pharmacy, Takasaki University of Health and Welfare, Takasaki, Japan
| | - Yuji Tanaka
- Laboratory of Molecular and Cellular Biology, Faculty of Pharmacy, Takasaki University of Health and Welfare, Takasaki, Japan
| | - Sachiko Ogasawara
- Department of Pathology, Kurume University School of Medicine, Kurume, Japan
| | - Chikashi Obuse
- Department of Biological Sciences, Graduate School of Science, Osaka University, Osaka Japan
| | - Jun-Ichi Nakayama
- Division of Chromatin Regulation, National Institute for Basic Biology, Okazaki, Japan
| | - Hirohisa Yano
- Department of Pathology, Kurume University School of Medicine, Kurume, Japan
| | - Makoto Tsuneoka
- Laboratory of Molecular and Cellular Biology, Faculty of Pharmacy, Takasaki University of Health and Welfare, Takasaki, Japan
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9
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Czech B, Munafò M, Ciabrelli F, Eastwood EL, Fabry MH, Kneuss E, Hannon GJ. piRNA-Guided Genome Defense: From Biogenesis to Silencing. Annu Rev Genet 2018; 52:131-157. [PMID: 30476449 PMCID: PMC10784713 DOI: 10.1146/annurev-genet-120417-031441] [Citation(s) in RCA: 270] [Impact Index Per Article: 45.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
PIWI-interacting RNAs (piRNAs) and their associated PIWI clade Argonaute proteins constitute the core of the piRNA pathway. In gonadal cells, this conserved pathway is crucial for genome defense, and its main function is to silence transposable elements. This is achieved through posttranscriptional and transcriptional gene silencing. Precursors that give rise to piRNAs require specialized transcription and transport machineries because piRNA biogenesis is a cytoplasmic process. The ping-pong cycle, a posttranscriptional silencing mechanism, combines the cleavage-dependent silencing of transposon RNAs with piRNA production. PIWI proteins also function in the nucleus, where they scan for nascent target transcripts with sequence complementarity, instructing transcriptional silencing and deposition of repressive chromatin marks at transposon loci. Although studies have revealed numerous factors that participate in each branch of the piRNA pathway, the precise molecular roles of these factors often remain unclear. In this review, we summarize our current understanding of the mechanisms involved in piRNA biogenesis and function.
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Affiliation(s)
- Benjamin Czech
- Cancer Research UK Cambridge Institute, University of Cambridge, Cambridge CB2 0RE, United Kingdom; ,
| | - Marzia Munafò
- Cancer Research UK Cambridge Institute, University of Cambridge, Cambridge CB2 0RE, United Kingdom; ,
| | - Filippo Ciabrelli
- Cancer Research UK Cambridge Institute, University of Cambridge, Cambridge CB2 0RE, United Kingdom; ,
| | - Evelyn L Eastwood
- Cancer Research UK Cambridge Institute, University of Cambridge, Cambridge CB2 0RE, United Kingdom; ,
| | - Martin H Fabry
- Cancer Research UK Cambridge Institute, University of Cambridge, Cambridge CB2 0RE, United Kingdom; ,
| | - Emma Kneuss
- Cancer Research UK Cambridge Institute, University of Cambridge, Cambridge CB2 0RE, United Kingdom; ,
| | - Gregory J Hannon
- Cancer Research UK Cambridge Institute, University of Cambridge, Cambridge CB2 0RE, United Kingdom; ,
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10
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Hosoya N, Ono M, Miyagawa K. Somatic role of SYCE2: an insulator that dissociates HP1α from H3K9me3 and potentiates DNA repair. Life Sci Alliance 2018; 1:e201800021. [PMID: 30456351 PMCID: PMC6238414 DOI: 10.26508/lsa.201800021] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Revised: 06/03/2018] [Accepted: 06/04/2018] [Indexed: 01/05/2023] Open
Abstract
The synaptonemal complex is a proteinaceous structure essential for meiotic recombination, and its components have been assumed to play a role exclusively in the germ line. However, SYCE2, a component constituting the synaptonemal complex, is expressed at varying levels in somatic cells. Considering its potent protein-binding activities, it may be possible that SYCE2 plays a somatic role by affecting nuclear functions. Here, we show that SYCE2 constitutively insulates HP1α from trimethylated histone H3 lysine 9 (H3K9me3) to promote DNA double-strand break repair. Unlike other HP1α-binding proteins, which use the canonical PXVXL motifs for their bindings, SYCE2 interacts with the chromoshadow domain of HP1α through its N-terminal hydrophobic sequence. SYCE2 reduces HP1α-H3K9me3 binding without affecting H3K9me3 levels and potentiates ataxia telangiectasia mutated-mediated double-strand break repair activity even in the absence of exogenous DNA damage. Such a somatic role of SYCE2 is ubiquitously observed even if its expression levels are low. These findings suggest that SYCE2 plays a somatic role in the link between the nuclear microenvironment and the DNA damage response potentials as a scaffold of HP1α localization.
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Affiliation(s)
- Noriko Hosoya
- Laboratory of Molecular Radiology, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
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11
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Wiley EA, Horrell S, Yoshino A, Schornak CC, Bagnani C, Chalker DL. Diversification of HP1-like Chromo Domain Proteins in Tetrahymena thermophila. J Eukaryot Microbiol 2017; 65:104-116. [PMID: 28692189 PMCID: PMC5762428 DOI: 10.1111/jeu.12443] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Revised: 06/23/2017] [Accepted: 06/27/2017] [Indexed: 12/18/2022]
Abstract
Proteins that possess a chromo domain are well-known for their roles in heterochromatin assembly and maintenance. The Heterochromatin Protein 1 (HP1) family, with a chromo domain and carboxy-terminal chromo shadow domain, targets heterochromatin through interaction with histone H3 methylated on lysine 9 (H3K9me2/3). The structural and functional diversity of these proteins observed in both fission yeast and metazoans correlate with chromatin specialization. To expand these studies, we examined chromo domain proteins in the ciliate Tetrahymena thermophila, which has functionally diverse and developmentally regulated heterochromatin domains. We identified thirteen proteins similar to HP1. Together they possess only a fraction of the possible chromo domain subtypes and most lack a recognizable chromo shadow domain. Using fluorescence microscopy to track chromatin localization of tagged proteins through the life cycle, we show evidence that in T. thermophila this family has diversified with biological roles in RNAi-directed DNA elimination, germline genome structure, and somatic heterochromatin. Those proteins with H3K27me3 binding sequence characteristics localize to chromatin in mature nuclei, whereas those with H3K9me2/3 binding characteristics localize to developing nuclei undergoing DNA elimination. Findings point to an expanded and diversified family of chromo domain proteins that parallels heterochromatin diversity in ciliates.
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Affiliation(s)
- Emily A Wiley
- W.M. Keck Science Center of Claremont McKenna, Pitzer, and Scripps Colleges, Claremont, California, 91711
| | - Scott Horrell
- Department of Biology, Washington University, St. Louis, Missouri, 63130
| | - Alyssa Yoshino
- W.M. Keck Science Center of Claremont McKenna, Pitzer, and Scripps Colleges, Claremont, California, 91711
| | - Cara C Schornak
- Department of Biology, Washington University, St. Louis, Missouri, 63130
| | - Claire Bagnani
- W.M. Keck Science Center of Claremont McKenna, Pitzer, and Scripps Colleges, Claremont, California, 91711
| | - Douglas L Chalker
- Department of Biology, Washington University, St. Louis, Missouri, 63130
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12
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Engineered holocytochrome c synthases that biosynthesize new cytochromes c. Proc Natl Acad Sci U S A 2017; 114:2235-2240. [PMID: 28196881 DOI: 10.1073/pnas.1615929114] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Cytochrome c (cyt c), required for electron transport in mitochondria, possesses a covalently attached heme cofactor. Attachment is catalyzed by holocytochrome c synthase (HCCS), leading to two thioether bonds between heme and a conserved CXXCH motif of cyt c In cyt c, histidine (His19) of CXXCH acts as an axial ligand to heme iron and upon release of holocytochrome c from HCCS, folding leads to formation of a second axial interaction with methionine (Met81). We previously discovered mutations in human HCCS that facilitate increased biosynthesis of cyt c in recombinant Escherichia coli Focusing on HCCS E159A, novel cyt c variants in quantities that are sufficient for biophysical analysis are biosynthesized. Cyt c H19M, the first bis-Met liganded cyt c, is compared with other axial ligand variants (M81A, M81H) and single thioether cyt c variants. For variants with axial ligand substitutions, electronic absorption, near-UV circular dichroism, and electron paramagnetic resonance spectroscopy provide evidence that axial ligands are changed and the heme environment is altered. Circular dichroism spectra in far UV and thermal denaturation analyses demonstrate that axial ligand changes do not affect secondary structures and stability. Redox potentials span a 400-mV range (+349 mV vs. standard hydrogen electrode, H19M; +252 mV, WT; -19 mV, M81A; -69 mV, M81H). We discuss the results in the context of a four-step mechanism for HCCS, whereby HCCS mutants such as E159A are enhanced in release (step 4) of cyt c from the HCCS active site; thus, we term these "release mutants."
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13
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Heterochromatin-Associated Proteins HP1a and Piwi Collaborate to Maintain the Association of Achiasmate Homologs in Drosophila Oocytes. Genetics 2016; 203:173-89. [PMID: 26984058 DOI: 10.1534/genetics.115.186460] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Accepted: 03/11/2016] [Indexed: 12/21/2022] Open
Abstract
Accurate segregation of homologous chromosomes during meiosis depends on their ability to remain physically connected throughout prophase I. For homologs that achieve a crossover, sister chromatid cohesion distal to the chiasma keeps them attached until anaphase I. However, in Drosophila melanogaster wild-type oocytes, chromosome 4 never recombines, and the X chromosome fails to cross over in 6-10% of oocytes. Proper segregation of these achiasmate homologs relies on their pericentric heterochromatin-mediated association, but the mechanism(s) underlying this attachment remains poorly understood. Using an inducible RNA interference (RNAi) strategy combined with fluorescence in situ hybridization (FISH) to monitor centromere proximal association of the achiasmate FM7a/X homolog pair, we asked whether specific heterochromatin-associated proteins are required for the association and proper segregation of achiasmate homologs in Drosophila oocytes. When we knock down HP1a, H3K9 methytransferases, or the HP1a binding partner Piwi during mid-prophase, we observe significant disruption of pericentric heterochromatin-mediated association of FM7a/X homologs. Furthermore, for both HP1a and Piwi knockdown oocytes, transgenic coexpression of the corresponding wild-type protein is able to rescue RNAi-induced defects, but expression of a mutant protein with a single amino acid change that disrupts the HP1a-Piwi interaction is unable to do so. We show that Piwi is stably bound to numerous sites along the meiotic chromosomes, including centromere proximal regions. In addition, reduction of HP1a or Piwi during meiotic prophase induces a significant increase in FM7a/X segregation errors. We present a speculative model outlining how HP1a and Piwi could collaborate to keep achiasmate chromosomes associated in a homology-dependent manner.
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Del Olmo I, López JA, Vázquez J, Raynaud C, Piñeiro M, Jarillo JA. Arabidopsis DNA polymerase ϵ recruits components of Polycomb repressor complex to mediate epigenetic gene silencing. Nucleic Acids Res 2016; 44:5597-614. [PMID: 26980282 PMCID: PMC4937302 DOI: 10.1093/nar/gkw156] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Accepted: 02/26/2016] [Indexed: 01/07/2023] Open
Abstract
Arabidopsis ESD7 locus encodes the catalytic subunit of the DNA Pol ϵ involved in the synthesis of the DNA leading strand and is essential for embryo viability. The hypomorphic allele esd7-1 is viable but displays a number of pleiotropic phenotypic alterations including an acceleration of flowering time. Furthermore, Pol ϵ is involved in the epigenetic silencing of the floral integrator genes FT and SOC1, but the molecular nature of the transcriptional gene silencing mechanisms involved remains elusive. Here we reveal that ESD7 interacts with components of the PRC2 such as CLF, EMF2 and MSI1, and that mutations in ESD7 cause a decrease in the levels of the H3K27me3 mark present in the chromatin of FT and SOC1. We also demonstrate that a domain of the C-terminal region of ESD7 mediates the binding to the different PRC2 components and this interaction is necessary for the proper recruitment of PRC2 to FT and SOC1 chromatin. We unveil the existence of interplay between the DNA replication machinery and the PcG complexes in epigenetic transcriptional silencing. These observations provide an insight into the mechanisms ensuring that the epigenetic code at pivotal loci in developmental control is faithfully transmitted to the progeny of eukaryotic cells.
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Affiliation(s)
- Iván Del Olmo
- Centro de Biotecnología y Genómica de Plantas (CBGP), UPM-INIA, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Campus de Montegancedo, 28223 Madrid, Spain
| | - Juan A López
- Proteomics Unit, Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), 28029 Madrid, Spain
| | - Jesús Vázquez
- Laboratory of Cardiovascular Proteomics, Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), 28029 Madrid, Spain
| | - Cécile Raynaud
- Université Paris-Sud, Institute of Plant Sciences Paris-Saclay IPS2 (Bâtiment 630), UMR CNRS-INRA 9213, Saclay Plant Sciences, 91405 Orsay, France
| | - Manuel Piñeiro
- Centro de Biotecnología y Genómica de Plantas (CBGP), UPM-INIA, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Campus de Montegancedo, 28223 Madrid, Spain
| | - José A Jarillo
- Centro de Biotecnología y Genómica de Plantas (CBGP), UPM-INIA, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Campus de Montegancedo, 28223 Madrid, Spain
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Yuan K, O'Farrell PH. TALE-light imaging reveals maternally guided, H3K9me2/3-independent emergence of functional heterochromatin in Drosophila embryos. Genes Dev 2016; 30:579-93. [PMID: 26915820 PMCID: PMC4782051 DOI: 10.1101/gad.272237.115] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Accepted: 01/26/2016] [Indexed: 11/25/2022]
Abstract
In this study, Yuan and O'Farrell investigated how heterochromatin is established during development. Using new methodology for live imaging that allows spatial and temporal resolution of heterochromatin formation during normal Drosophila embryogenesis, they show that a maternal signal can act transgenerationally to influence the formation of heterochromatin on a satellite sequence. Metazoans start embryogenesis with a relatively naïve genome. The transcriptionally inert, late-replicating heterochromatic regions, including the constitutive heterochromatin on repetitive sequences near centromeres and telomeres, need to be re-established during development. To explore the events initiating heterochromatin formation and examine their temporal control, sequence specificity, and immediate regulatory consequence, we established a live imaging approach that enabled visualization of steps in heterochromatin emergence on specific satellite sequences during the mid-blastula transition (MBT) in Drosophila. Unexpectedly, only a subset of satellite sequences, including the 359-base-pair (bp) repeat sequence, recruited HP1a at the MBT. The recruitment of HP1a to the 359-bp repeat was dependent on HP1a's chromoshadow domain but not its chromodomain and was guided by maternally provided signals. HP1a recruitment to the 359-bp repeat was required for its programmed shift to later replication, and ectopic recruitment of HP1a was sufficient to delay replication timing of a different repeat. Our results reveal that emergence of constitutive heterochromatin follows a stereotyped developmental program in which different repetitive sequences use distinct interactions and independent pathways to arrive at a heterochromatic state. This differential emergence of heterochromatin on various repetitive sequences changes their replication order and remodels the DNA replication schedule during embryonic development.
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Affiliation(s)
- Kai Yuan
- Department of Biochemistry, University of California at San Francisco, San Francisco, California 94158, USA
| | - Patrick H O'Farrell
- Department of Biochemistry, University of California at San Francisco, San Francisco, California 94158, USA
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16
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Vad-Nielsen J, Nielsen AL. Beyond the histone tale: HP1α deregulation in breast cancer epigenetics. Cancer Biol Ther 2015; 16:189-200. [PMID: 25588111 DOI: 10.1080/15384047.2014.1001277] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Heterochromatin protein 1α (HP1α) encoded from the CBX5-gene is an evolutionary conserved protein that binds histone H3 di- or tri-methylated at position lysine 9 (H3K9me2/3), a hallmark for heterochromatin, and has an essential role in forming higher order chromatin structures. HP1α has diverse functions in heterochromatin formation, gene regulation, and mitotic progression, and forms complex networks of gene, RNA, and protein interactions. Emerging evidence has shown that HP1α serves a unique biological role in breast cancer related processes and in particular for epigenetic control mechanisms involved in aberrant cell proliferation and metastasis. However, how HP1α deregulation plays dual mechanistic functions for cancer cell proliferation and metastasis suppression and the underlying cellular mechanisms are not yet comprehensively described. In this paper we provide an overview of the role of HP1α as a new sight of epigenetics in proliferation and metastasis of human breast cancer. This highlights the importance of addressing HP1α in breast cancer diagnostics and therapeutics.
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Key Words
- CBX, chromobox homolog
- CD, chromo domain
- CSC, cancer stem cells
- CSD, cromo shadow domain
- CTE, C-terminal extension
- DNMT, DNA-methyltransferase
- EMT, epithelial-to-mesenchymal transition
- HDMT, histone demethylase
- HMT, histone methyltransferase
- HP1, heterochromatin protein 1
- NTE, N-terminal extension
- PEV, position effect variegation
- SOMU, sumoylation
- TGS, transcriptional gene silencing
- TSS, transcriptional start site
- bp, base pair
- breast-cancer, metastasis
- chromatin
- epigenetics
- histone-modifications
- invasion
- mitosis
- proliferation
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Darré L, Machado MR, Brandner AF, González HC, Ferreira S, Pantano S. SIRAH: A Structurally Unbiased Coarse-Grained Force Field for Proteins with Aqueous Solvation and Long-Range Electrostatics. J Chem Theory Comput 2015; 11:723-39. [DOI: 10.1021/ct5007746] [Citation(s) in RCA: 99] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Leonardo Darré
- Institut Pasteur de Montevideo, Montevideo, Uruguay
- Department
of Chemistry, King’s College, London, United Kingdom
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Théron E, Dennis C, Brasset E, Vaury C. Distinct features of the piRNA pathway in somatic and germ cells: from piRNA cluster transcription to piRNA processing and amplification. Mob DNA 2014; 5:28. [PMID: 25525472 PMCID: PMC4269861 DOI: 10.1186/s13100-014-0028-y] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2014] [Accepted: 11/12/2014] [Indexed: 02/05/2023] Open
Abstract
Transposable elements (TEs) are major components of genomes. Their mobilization may affect genomic expression and be a threat to genetic stability. This is why they have to be tightly regulated by a dedicated system. In the reproductive tissues of a large range of organisms, they are repressed by a subclass of small interfering RNAs called piRNAs (PIWI interacting RNAs). In Drosophila melanogaster, piRNAs are produced both in the ovarian germline cells and in their surrounding somatic cells. Accumulating evidence suggests that germinal and somatic piRNA pathways are far more different than previously thought. Here we review the current knowledge on piRNA production in both these cell types, and explore their similarities and differences.
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Affiliation(s)
- Emmanuelle Théron
- Laboratoire GReD, Faculté de Médecine, Clermont Université, Université d'Auvergne, 28 Place H Dunant, 63000 Clermont-Ferrand, France.,Inserm, U 1103, F-63001 Clermont-Ferrand, France.,CNRS, UMR 6293, F-63001 Clermont-Ferrand, France
| | - Cynthia Dennis
- Laboratoire GReD, Faculté de Médecine, Clermont Université, Université d'Auvergne, 28 Place H Dunant, 63000 Clermont-Ferrand, France.,Inserm, U 1103, F-63001 Clermont-Ferrand, France.,CNRS, UMR 6293, F-63001 Clermont-Ferrand, France
| | - Emilie Brasset
- Laboratoire GReD, Faculté de Médecine, Clermont Université, Université d'Auvergne, 28 Place H Dunant, 63000 Clermont-Ferrand, France.,Inserm, U 1103, F-63001 Clermont-Ferrand, France.,CNRS, UMR 6293, F-63001 Clermont-Ferrand, France
| | - Chantal Vaury
- Laboratoire GReD, Faculté de Médecine, Clermont Université, Université d'Auvergne, 28 Place H Dunant, 63000 Clermont-Ferrand, France.,Inserm, U 1103, F-63001 Clermont-Ferrand, France.,CNRS, UMR 6293, F-63001 Clermont-Ferrand, France
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Nishibuchi G, Nakayama JI. Biochemical and structural properties of heterochromatin protein 1: understanding its role in chromatin assembly. J Biochem 2014; 156:11-20. [DOI: 10.1093/jb/mvu032] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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20
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Canzio D, Larson A, Narlikar GJ. Mechanisms of functional promiscuity by HP1 proteins. Trends Cell Biol 2014; 24:377-86. [PMID: 24618358 DOI: 10.1016/j.tcb.2014.01.002] [Citation(s) in RCA: 138] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2013] [Revised: 01/19/2014] [Accepted: 01/22/2014] [Indexed: 01/03/2023]
Abstract
Heterochromatin protein 1 (HP1) proteins were originally identified as critical components in heterochromatin-mediated gene silencing and are now recognized to play essential roles in several other processes including gene activation. Several eukaryotes possess more than one HP1 paralog. Despite high sequence conservation, the HP1 paralogs achieve diverse functions. Further, in many cases, the same HP1 paralog is implicated in multiple functions. Recent biochemical studies have revealed interesting paralog-specific biophysical differences and unanticipated conformational versatility in HP1 proteins that may account for this functional promiscuity. Here we review these findings and describe a molecular framework that aims to link the conformational flexibility of HP1 proteins observed in vitro with their functional promiscuity observed in vivo.
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Affiliation(s)
- Daniele Canzio
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Adam Larson
- Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, CA 94158, USA; Tetrad Graduate Program, University of California San Francisco, San Francisco, CA 94158, USA
| | - Geeta J Narlikar
- Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, CA 94158, USA.
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