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Jelinska C, Kannan S, Frosi Y, Ramlan SR, Winnerdy F, Lakshminarayanan R, Johannes CW, Brown CJ, Phan AT, Rhodes D, Verma CS. Stitched peptides as potential cell permeable inhibitors of oncogenic DAXX protein. RSC Chem Biol 2023; 4:1096-1110. [PMID: 38033728 PMCID: PMC10685803 DOI: 10.1039/d3cb00149k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2023] [Accepted: 09/25/2023] [Indexed: 12/02/2023] Open
Abstract
DAXX (Death Domain Associated Protein 6) is frequently upregulated in various common cancers, and its suppression has been linked to reduced tumor progression. Consequently, DAXX has gained significant interest as a therapeutic target in such cancers. DAXX is known to function in several critical biological pathways including chromatin remodelling, transcription regulation, and DNA repair. Leveraging structural information, we have designed and developed a novel set of stapled/stitched peptides that specifically target a surface on the N-terminal helical bundle domain of DAXX. This surface serves as the anchor point for binding to multiple interaction partners, such as Rassf1C, p53, Mdm2, and ATRX, as well as for the auto-regulation of the DAXX N-terminal SUMO interaction motif (SIM). Our experiments demonstrate that these peptides effectively bind to and inhibit DAXX with a higher affinity than the known interaction partners. Furthermore, these peptides release the auto-inhibited SIM, enabling it to interact with SUMO-1. Importantly, we have developed stitched peptides that can enter cells, maintaining their intracellular concentrations at nanomolar levels even after 24 hours, without causing any membrane perturbation. Collectively, our findings suggest that these stitched peptides not only serve as valuable tools for probing the molecular interactions of DAXX but also hold potential as precursors to the development of therapeutic interventions.
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Affiliation(s)
- Clare Jelinska
- NTU Institute of Structural Biology, Experimental Medicine Building Level 06-01, 59 Nanyang Drive 636921 Singapore
- NTU School of Biological Sciences, 60 Nanyang Drive 637551 Singapore
- NTU Lee Kong Chian School of Medicine, Experimental Medicine Building, 59 Nanyang Drive 636921 Singapore
| | | | - Yuri Frosi
- DITL, Institute of Cellular and Molecular Biology (A*STAR), 8a Biomedical Grove 138648 Singapore
| | - Siti Radhiah Ramlan
- DITL, Institute of Cellular and Molecular Biology (A*STAR), 8a Biomedical Grove 138648 Singapore
| | - Fernaldo Winnerdy
- NTU Institute of Structural Biology, Experimental Medicine Building Level 06-01, 59 Nanyang Drive 636921 Singapore
| | - Rajamani Lakshminarayanan
- Ocular Infections and Anti-Microbials Research Group, Singapore Eye Research Institute, The Academia, 20 College Road Singapore 169856 Singapore
- Department of Pharmacy, National University of Singapore Singapore 117543 Singapore
- Academic Clinical Program in Ophthalmology and Visual Sciences Academic Clinical Program, Duke-NUS Medical School 169857 Singapore
| | - Charles W Johannes
- DITL, Institute of Cellular and Molecular Biology (A*STAR), 8a Biomedical Grove 138648 Singapore
| | - Christopher J Brown
- DITL, Institute of Cellular and Molecular Biology (A*STAR), 8a Biomedical Grove 138648 Singapore
| | - Anh-Tuan Phan
- NTU Institute of Structural Biology, Experimental Medicine Building Level 06-01, 59 Nanyang Drive 636921 Singapore
- NTU School of Physical and Mathematical Sciences. 21 Nanyang link 637371 Singapore
| | - Daniela Rhodes
- NTU Institute of Structural Biology, Experimental Medicine Building Level 06-01, 59 Nanyang Drive 636921 Singapore
- NTU School of Biological Sciences, 60 Nanyang Drive 637551 Singapore
- NTU Lee Kong Chian School of Medicine, Experimental Medicine Building, 59 Nanyang Drive 636921 Singapore
| | - Chandra S Verma
- NTU School of Biological Sciences, 60 Nanyang Drive 637551 Singapore
- Bioinformatics institute (A*STAR), 30 Biopolis Street, Matrix Level 07-01 138671 Singapore
- Department of Biological Sciences, National University of Singapore Block S3 #05-01 16 Science Drive 4 117558 Singapore
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2
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Canat A, Veillet A, Batrin R, Dubourg C, Lhoumaud P, Arnau-Romero P, Greenberg MVC, Bonhomme F, Arimondo PB, Illingworth R, Fabre E, Therizols P. DAXX safeguards heterochromatin formation in embryonic stem cells. J Cell Sci 2023; 136:jcs261092. [PMID: 37655670 DOI: 10.1242/jcs.261092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Accepted: 08/25/2023] [Indexed: 09/02/2023] Open
Abstract
Genomes comprise a large fraction of repetitive sequences folded into constitutive heterochromatin, which protect genome integrity and cell identity. De novo formation of heterochromatin during preimplantation development is an essential step for preserving the ground-state of pluripotency and the self-renewal capacity of embryonic stem cells (ESCs). However, the molecular mechanisms responsible for the remodeling of constitutive heterochromatin are largely unknown. Here, we identify that DAXX, an H3.3 chaperone essential for the maintenance of mouse ESCs in the ground state, accumulates in pericentromeric regions independently of DNA methylation. DAXX recruits PML and SETDB1 to promote the formation of heterochromatin, forming foci that are hallmarks of ground-state ESCs. In the absence of DAXX or PML, the three-dimensional (3D) architecture and physical properties of pericentric and peripheral heterochromatin are disrupted, resulting in de-repression of major satellite DNA, transposable elements and genes associated with the nuclear lamina. Using epigenome editing tools, we observe that H3.3, and specifically H3.3K9 modification, directly contribute to maintaining pericentromeric chromatin conformation. Altogether, our data reveal that DAXX is crucial for the maintenance and 3D organization of the heterochromatin compartment and protects ESC viability.
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Affiliation(s)
- Antoine Canat
- Université de Paris, Laboratoire Génomes, Biologie Cellulaire et Thérapeutiques, CNRS UMR7212, INSERM U944, Institut de Recherche St Louis, F-75010 Paris, France
| | - Adeline Veillet
- Université de Paris, Laboratoire Génomes, Biologie Cellulaire et Thérapeutiques, CNRS UMR7212, INSERM U944, Institut de Recherche St Louis, F-75010 Paris, France
| | - Renaud Batrin
- Université de Paris, Laboratoire Génomes, Biologie Cellulaire et Thérapeutiques, CNRS UMR7212, INSERM U944, Institut de Recherche St Louis, F-75010 Paris, France
| | - Clara Dubourg
- Université de Paris, Laboratoire Génomes, Biologie Cellulaire et Thérapeutiques, CNRS UMR7212, INSERM U944, Institut de Recherche St Louis, F-75010 Paris, France
| | | | - Pol Arnau-Romero
- Université Paris Cité, CNRS, Institut Jacques Monod, F-75013 Paris, France
| | | | - Frédéric Bonhomme
- Institut Pasteur, Université Paris Cité, CNRS, Epigenetic Chemical Biology, UMR 3523, F-75724 Paris, France
| | - Paola B Arimondo
- Institut Pasteur, Université Paris Cité, CNRS, Epigenetic Chemical Biology, UMR 3523, F-75724 Paris, France
| | - Robert Illingworth
- Centre for Regenerative Medicine, Institute for Regeneration and Repair, The University of Edinburgh, Edinburgh BioQuarter, 5 Little France Drive, Edinburgh EH16 4UU, UK
| | - Emmanuelle Fabre
- Université de Paris, Laboratoire Génomes, Biologie Cellulaire et Thérapeutiques, CNRS UMR7212, INSERM U944, Institut de Recherche St Louis, F-75010 Paris, France
| | - Pierre Therizols
- Université de Paris, Laboratoire Génomes, Biologie Cellulaire et Thérapeutiques, CNRS UMR7212, INSERM U944, Institut de Recherche St Louis, F-75010 Paris, France
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3
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Mahmud I, Tian G, Wang J, Hutchinson TE, Kim BJ, Awasthee N, Hale S, Meng C, Moore A, Zhao L, Lewis JE, Waddell A, Wu S, Steger JM, Lydon ML, Chait A, Zhao LY, Ding H, Li JL, Purayil HT, Huo Z, Daaka Y, Garrett TJ, Liao D. DAXX drives de novo lipogenesis and contributes to tumorigenesis. Nat Commun 2023; 14:1927. [PMID: 37045819 PMCID: PMC10097704 DOI: 10.1038/s41467-023-37501-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2019] [Accepted: 03/20/2023] [Indexed: 04/14/2023] Open
Abstract
Cancer cells exhibit elevated lipid synthesis. In breast and other cancer types, genes involved in lipid production are highly upregulated, but the mechanisms that control their expression remain poorly understood. Using integrated transcriptomic, lipidomic, and molecular studies, here we report that DAXX is a regulator of oncogenic lipogenesis. DAXX depletion attenuates, while its overexpression enhances, lipogenic gene expression, lipogenesis, and tumor growth. Mechanistically, DAXX interacts with SREBP1 and SREBP2 and activates SREBP-mediated transcription. DAXX associates with lipogenic gene promoters through SREBPs. Underscoring the critical roles for the DAXX-SREBP interaction for lipogenesis, SREBP2 knockdown attenuates tumor growth in cells with DAXX overexpression, and DAXX mutants unable to bind SREBP1/2 have weakened activity in promoting lipogenesis and tumor growth. Remarkably, a DAXX mutant deficient of SUMO-binding fails to activate SREBP1/2 and lipogenesis due to impaired SREBP binding and chromatin recruitment and is defective of stimulating tumorigenesis. Hence, DAXX's SUMO-binding activity is critical to oncogenic lipogenesis. Notably, a peptide corresponding to DAXX's C-terminal SUMO-interacting motif (SIM2) is cell-membrane permeable, disrupts the DAXX-SREBP1/2 interactions, and inhibits lipogenesis and tumor growth. These results establish DAXX as a regulator of lipogenesis and a potential therapeutic target for cancer therapy.
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Affiliation(s)
- Iqbal Mahmud
- Department of Anatomy and Cell Biology, UF Health Cancer Center, University of Florida College of Medicine, Gainesville, FL, USA
- Southeast Center for Integrated Metabolomics, Clinical and Translational Science Institute, University of Florida, Gainesville, FL, USA
- Department of Pathology, Immunology and Laboratory Medicine, University of Florida College of Medicine, Gainesville, FL, USA
- Department of Bioinformatics and Computational Biology, University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Guimei Tian
- Department of Anatomy and Cell Biology, UF Health Cancer Center, University of Florida College of Medicine, Gainesville, FL, USA
| | - Jia Wang
- Department of Anatomy and Cell Biology, UF Health Cancer Center, University of Florida College of Medicine, Gainesville, FL, USA
- The Affiliated Cancer Hospital of Zhengzhou University & Henan Cancer Hospital, 450008, Zhengzhou, Henan, China
| | - Tarun E Hutchinson
- Department of Anatomy and Cell Biology, UF Health Cancer Center, University of Florida College of Medicine, Gainesville, FL, USA
| | - Brandon J Kim
- Department of Anatomy and Cell Biology, UF Health Cancer Center, University of Florida College of Medicine, Gainesville, FL, USA
| | - Nikee Awasthee
- Department of Anatomy and Cell Biology, UF Health Cancer Center, University of Florida College of Medicine, Gainesville, FL, USA
| | - Seth Hale
- Department of Anatomy and Cell Biology, UF Health Cancer Center, University of Florida College of Medicine, Gainesville, FL, USA
| | - Chengcheng Meng
- Department of Anatomy and Cell Biology, UF Health Cancer Center, University of Florida College of Medicine, Gainesville, FL, USA
| | - Allison Moore
- Department of Anatomy and Cell Biology, UF Health Cancer Center, University of Florida College of Medicine, Gainesville, FL, USA
| | - Liming Zhao
- Department of Anatomy and Cell Biology, UF Health Cancer Center, University of Florida College of Medicine, Gainesville, FL, USA
| | - Jessica E Lewis
- Department of Anatomy and Cell Biology, UF Health Cancer Center, University of Florida College of Medicine, Gainesville, FL, USA
| | - Aaron Waddell
- Department of Anatomy and Cell Biology, UF Health Cancer Center, University of Florida College of Medicine, Gainesville, FL, USA
| | - Shangtao Wu
- Department of Anatomy and Cell Biology, UF Health Cancer Center, University of Florida College of Medicine, Gainesville, FL, USA
| | - Julia M Steger
- Department of Anatomy and Cell Biology, UF Health Cancer Center, University of Florida College of Medicine, Gainesville, FL, USA
| | - McKenzie L Lydon
- Department of Anatomy and Cell Biology, UF Health Cancer Center, University of Florida College of Medicine, Gainesville, FL, USA
| | - Aaron Chait
- Department of Anatomy and Cell Biology, UF Health Cancer Center, University of Florida College of Medicine, Gainesville, FL, USA
| | - Lisa Y Zhao
- Department of Anatomy and Cell Biology, UF Health Cancer Center, University of Florida College of Medicine, Gainesville, FL, USA
- Department of Medicine, University of Florida College of Medicine, Gainesville, FL, USA
| | - Haocheng Ding
- Department of Biostatistics, University of Florida, Gainesville, FL, USA
| | - Jian-Liang Li
- Integrative Bioinformatics, National Institute of Environmental Health Sciences, Research Triangle Park, NC, USA
| | - Hamsa Thayele Purayil
- Department of Anatomy and Cell Biology, UF Health Cancer Center, University of Florida College of Medicine, Gainesville, FL, USA
| | - Zhiguang Huo
- Department of Biostatistics, University of Florida, Gainesville, FL, USA
| | - Yehia Daaka
- Department of Anatomy and Cell Biology, UF Health Cancer Center, University of Florida College of Medicine, Gainesville, FL, USA
| | - Timothy J Garrett
- Southeast Center for Integrated Metabolomics, Clinical and Translational Science Institute, University of Florida, Gainesville, FL, USA
- Department of Pathology, Immunology and Laboratory Medicine, University of Florida College of Medicine, Gainesville, FL, USA
| | - Daiqing Liao
- Department of Anatomy and Cell Biology, UF Health Cancer Center, University of Florida College of Medicine, Gainesville, FL, USA.
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Wen T, Chen QY. Dynamic Activity of Histone H3-Specific Chaperone Complexes in Oncogenesis. Front Oncol 2022; 11:806974. [PMID: 35087762 PMCID: PMC8786718 DOI: 10.3389/fonc.2021.806974] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Accepted: 12/15/2021] [Indexed: 11/30/2022] Open
Abstract
Canonical histone H3.1 and variant H3.3 deposit at different sites of the chromatin via distinct histone chaperones. Histone H3.1 relies on chaperone CAF-1 to mediate replication-dependent nucleosome assembly during S-phase, while H3.3 variant is regulated and incorporated into the chromatin in a replication-independent manner through HIRA and DAXX/ATRX. Current literature suggests that dysregulated expression of histone chaperones may be implicated in tumor progression. Notably, ectopic expression of CAF-1 can promote a switch between canonical H3.1 and H3 variants in the chromatin, impair the chromatic state, lead to chromosome instability, and impact gene transcription, potentially contributing to carcinogenesis. This review focuses on the chaperone proteins of H3.1 and H3.3, including structure, regulation, as well as their oncogenic and tumor suppressive functions in tumorigenesis.
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Affiliation(s)
- Ting Wen
- Department of Cell Biology and Genetics, School of Basic Medical Sciences, Xi'an Jiaotong University, Xi'an, China
| | - Qiao Yi Chen
- Department of Cell Biology and Genetics, School of Basic Medical Sciences, Xi'an Jiaotong University, Xi'an, China
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5
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Bogolyubova I, Bogolyubov D. DAXX Is a Crucial Factor for Proper Development of Mammalian Oocytes and Early Embryos. Int J Mol Sci 2021; 22:ijms22031313. [PMID: 33525665 PMCID: PMC7866053 DOI: 10.3390/ijms22031313] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Revised: 01/22/2021] [Accepted: 01/26/2021] [Indexed: 12/18/2022] Open
Abstract
The Death-domain associated protein 6 (DAXX) is an evolutionarily conserved and ubiquitously expressed multifunctional protein that is implicated in many cellular processes, including transcription, cellular proliferation, cell cycle regulation, Fas-induced apoptosis, and many other events. In the nucleus, DAXX interacts with transcription factors, epigenetic modifiers, and chromatin-remodeling proteins such as the transcription regulator ATRX-the α-thalassemia/mental retardation syndrome X-linked ATP-dependent helicase II. Accordingly, DAXX is considered one of the main players involved in chromatin silencing and one of the most important factors that maintain integrity of the genome. In this brief review, we summarize available data regarding the general and specific functions of DAXX in mammalian early development, with special emphasis on the function of DAXX as a chaperone of the histone variant H3.3. Since H3.3 plays a key role in the developmental processes, especially in the pronounced rearrangements of heterochromatin compartment during oogenesis and embryogenesis, DAXX can be considered as an important factor supporting proper development. Specifically, loss of DAXX affects the recruitment of ATRX, transcription of tandem repeats and telomere functions, which results in a decrease in the viability of early embryos.
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Liu H, Liu Z, Gao M, Hu X, Sun R, Shen X, Liu F, Shen J, Shan Z, Lei L. The Effects of Daxx Knockout on Pluripotency and Differentiation of Mouse Induced Pluripotent Stem Cells. Cell Reprogram 2020; 22:90-98. [PMID: 32150692 DOI: 10.1089/cell.2019.0071] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Induced pluripotent stem cell (iPSC) technology refers to the reprogramming of terminally differentiated somatic cells into pluripotent stem cells by introducing specific transcription factors that are known to regulate pluripotency, including Oct4, Sox2, Klf4, and c-Myc. In this study, we reprogrammed the primary fibroblasts isolated from the Daxxflox/flox mice, which carry the Oct4-green fluorescent protein reporter, and employed wild-type littermates as a control to induce iPSCs, then knocked out Daxx by infecting with Cre virus at the cellular level. The pluripotency and self-renewal capacity of iPSCs were determined. In addition, Daxx deletion altered the pluripotency marker (Nanog, Oct4) expression and displayed neural differentiation defects. Particularly, by performing transcriptome analysis, we observed that numerous ribosome biogenesis-related genes were altered, and quantitative polymerase chain reaction revealed that the expression of rDNA-related genes, 47S and 18S, was elevated after Daxx deletion. Finally, we illustrated that the expression of the neurodevelopment-related gene was upregulated both in iPSCs and differentiated neurospheres. Taken together, we demonstrated that Daxx knockout promotes the expression of rDNA, pluripotency, and neurodevelopment genes, which may improve the differentiation abilities of mouse iPSCs (miPSCs).
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Affiliation(s)
- Hui Liu
- Department of Histology and Embryology, Harbin Medical University, Harbin, China
| | - Zhaojun Liu
- Department of Histology and Embryology, Harbin Medical University, Harbin, China
| | - Meng Gao
- Department of Histology and Embryology, Harbin Medical University, Harbin, China
| | - Xinglin Hu
- Department of Histology and Embryology, Harbin Medical University, Harbin, China
| | - Ruizhen Sun
- Department of Histology and Embryology, Harbin Medical University, Harbin, China
| | - Xinghui Shen
- Department of Histology and Embryology, Harbin Medical University, Harbin, China
| | - Feng Liu
- Department of Breast Surgery, Cancer Hospital Affiliated to Harbin Medical University, Harbin, China
| | - Jingling Shen
- Institute of Life Science, Wenzhou University, Wenzhou, China
| | - Zhiyan Shan
- Department of Histology and Embryology, Harbin Medical University, Harbin, China
| | - Lei Lei
- Department of Histology and Embryology, Harbin Medical University, Harbin, China
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Mahmud I, Liao D. DAXX in cancer: phenomena, processes, mechanisms and regulation. Nucleic Acids Res 2019; 47:7734-7752. [PMID: 31350900 PMCID: PMC6735914 DOI: 10.1093/nar/gkz634] [Citation(s) in RCA: 68] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Revised: 07/05/2019] [Accepted: 07/12/2019] [Indexed: 12/13/2022] Open
Abstract
DAXX displays complex biological functions. Remarkably, DAXX overexpression is a common feature in diverse cancers, which correlates with tumorigenesis, disease progression and treatment resistance. Structurally, DAXX is modular with an N-terminal helical bundle, a docking site for many DAXX interactors (e.g. p53 and ATRX). DAXX's central region folds with the H3.3/H4 dimer, providing a H3.3-specific chaperoning function. DAXX has two functionally critical SUMO-interacting motifs. These modules are connected by disordered regions. DAXX's structural features provide a framework for deciphering how DAXX mechanistically imparts its functions and how its activity is regulated. DAXX modulates transcription through binding to transcription factors, epigenetic modifiers, and chromatin remodelers. DAXX's localization in the PML nuclear bodies also plays roles in transcriptional regulation. DAXX-regulated genes are likely important effectors of its biological functions. Deposition of H3.3 and its interactions with epigenetic modifiers are likely key events for DAXX to regulate transcription, DNA repair, and viral infection. Interactions between DAXX and its partners directly impact apoptosis and cell signaling. DAXX's activity is regulated by posttranslational modifications and ubiquitin-dependent degradation. Notably, the tumor suppressor SPOP promotes DAXX degradation in phase-separated droplets. We summarize here our current understanding of DAXX's complex functions with a focus on how it promotes oncogenesis.
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Affiliation(s)
- Iqbal Mahmud
- Department of Anatomy and Cell Biology, UF Health Cancer Center, University of Florida College of Medicine, 1333 Center Drive, Gainesville, FL 32610-0235, USA
| | - Daiqing Liao
- Department of Anatomy and Cell Biology, UF Health Cancer Center, University of Florida College of Medicine, 1333 Center Drive, Gainesville, FL 32610-0235, USA
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Abstract
OBJECTIVES DAXX immunohistochemistry (IHC) is often used as a surrogate for sequencing. We aimed to elucidate the sensitivity of IHC for DAXX mutation. METHODS All pancreatic neuroendocrine tumors (PanNETs) with DAXX mutations detected by sequencing and a subset of DAXX wild-type PanNETs were analyzed for DAXX expression by IHC. RESULTS Of 154 PanNETs with MSK-IMPACT testing, 36 (30%) harbored DAXX mutations. DAXX mutations were associated with TSC2 mutations (46% vs 10%, P < 0.0001), tended to co-occur with MEN1 mutations (63% vs 49%, P = 0.11), and tended to be mutually exclusive with ATRX mutations (11% vs 25%, P = 0.053). Of 27 available DAXX mutant PanNETs, 23 lost DAXX expression (85.2%). All 4 DAXX mutants with retained expression harbored DAXX mutations within the SUMO-interacting motif of the last exon. Telomere-specific fluorescence in situ hybridization demonstrated alternative lengthening of telomeres in all 4 cases. Of 20 PanNETs with wild-type DAXX, 19 retained DAXX IHC expression (95%). CONCLUSIONS The sensitivity and specificity of IHC for DAXX mutation are 85% and 95%, respectively. Last exon DAXX mutant PanNETs often show alternative lengthening of telomeres despite retained DAXX expression, likely due to escape of nonmediated decay.
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Cancer Mutations of the Tumor Suppressor SPOP Disrupt the Formation of Active, Phase-Separated Compartments. Mol Cell 2018; 72:19-36.e8. [PMID: 30244836 DOI: 10.1016/j.molcel.2018.08.027] [Citation(s) in RCA: 238] [Impact Index Per Article: 39.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Revised: 05/29/2018] [Accepted: 08/03/2018] [Indexed: 12/30/2022]
Abstract
Mutations in the tumor suppressor SPOP (speckle-type POZ protein) cause prostate, breast, and other solid tumors. SPOP is a substrate adaptor of the cullin3-RING ubiquitin ligase and localizes to nuclear speckles. Although cancer-associated mutations in SPOP interfere with substrate recruitment to the ligase, mechanisms underlying assembly of SPOP with its substrates in liquid nuclear bodies and effects of SPOP mutations on assembly are poorly understood. Here, we show that substrates trigger phase separation of SPOP in vitro and co-localization in membraneless organelles in cells. Enzymatic activity correlates with cellular co-localization and in vitro mesoscale assembly formation. Disease-associated SPOP mutations that lead to the accumulation of proto-oncogenic proteins interfere with phase separation and co-localization in membraneless organelles, suggesting that substrate-directed phase separation of this E3 ligase underlies the regulation of ubiquitin-dependent proteostasis.
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Ueda H, Akiyama Y, Shimada S, Mogushi K, Serizawa M, Matsumura S, Mitsunori Y, Aihara A, Ban D, Ochiai T, Kudo A, Tanabe M, Tanaka S. Tumor suppressor functions of DAXX through histone H3.3/H3K9me3 pathway in pancreatic NETs. Endocr Relat Cancer 2018; 25:619-631. [PMID: 29599123 DOI: 10.1530/erc-17-0328] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Accepted: 03/28/2018] [Indexed: 12/13/2022]
Abstract
Pancreatic neuroendocrine tumors (PanNETs) have considerable malignant potential. Frequent somatic mutations and loss of DAXX protein expression have been found in PanNETs. DAXX is known as a transcriptional repressor; however, molecular functions underlying DAXX loss remain unclear in PanNETs. We evaluated DAXX expression by immunohistochemistry in 44 PanNETs. DAXX-knockdown (KD) and -knockout (KO) PanNET cells were analyzed for in vitro and vivo The target genes were screened by microarray and chromatin immunoprecipitation (ChIP) assays for DAXX, histone H3.3 and H3K9me3 complex. In clinicopathological features, low DAXX expression was significantly correlated with nonfunctional tumors, higher Ki-67 index and WHO grade. Microarray and ChIP assays of DAXX-KD/KO identified 12 genes as the direct targets of DAXX transcriptional repressor. Among them, expression of five genes including STC2 was suppressed by DAXX/H3.3/H3K9me3 pathway. DAXX-KD/KO cells enhanced sphere forming activity, but its effect was suppressed by knockdown of STC2 In xenograft models, tumorigenicity and tumor vessel density were significantly increased in DAXX-KO cells with high expression of STC2. Clinically, higher recurrence rate was recognized in PanNETs with low expression of DAXX and high expression of STC2 than others (P = 0.018). Our data suggest that DAXX plays as a tumor suppressor and DAXX/H3.3 complex suppresses target genes by promoting H3K9me3 in PanNETs. Combination of DAXX loss and its target gene STC2 overexpression might be effective biomarkers and therapeutic candidates.
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Affiliation(s)
- Hiroki Ueda
- Department of Molecular OncologyGraduate School of Medicine, Tokyo Medical and Dental University, Tokyo, Japan
- Department of Hepatobiliary and Pancreatic SurgeryGraduate School of Medicine, Tokyo Medical and Dental University, Tokyo, Japan
| | - Yoshimitsu Akiyama
- Department of Molecular OncologyGraduate School of Medicine, Tokyo Medical and Dental University, Tokyo, Japan
| | - Shu Shimada
- Department of Molecular OncologyGraduate School of Medicine, Tokyo Medical and Dental University, Tokyo, Japan
| | - Kaoru Mogushi
- Department of Molecular OncologyGraduate School of Medicine, Tokyo Medical and Dental University, Tokyo, Japan
| | - Misaki Serizawa
- Department of Molecular OncologyGraduate School of Medicine, Tokyo Medical and Dental University, Tokyo, Japan
| | - Satoshi Matsumura
- Department of Hepatobiliary and Pancreatic SurgeryGraduate School of Medicine, Tokyo Medical and Dental University, Tokyo, Japan
| | - Yusuke Mitsunori
- Department of Hepatobiliary and Pancreatic SurgeryGraduate School of Medicine, Tokyo Medical and Dental University, Tokyo, Japan
| | - Arihiro Aihara
- Department of Hepatobiliary and Pancreatic SurgeryGraduate School of Medicine, Tokyo Medical and Dental University, Tokyo, Japan
| | - Daisuke Ban
- Department of Hepatobiliary and Pancreatic SurgeryGraduate School of Medicine, Tokyo Medical and Dental University, Tokyo, Japan
| | - Takanori Ochiai
- Department of Hepatobiliary and Pancreatic SurgeryGraduate School of Medicine, Tokyo Medical and Dental University, Tokyo, Japan
| | - Atsushi Kudo
- Department of Hepatobiliary and Pancreatic SurgeryGraduate School of Medicine, Tokyo Medical and Dental University, Tokyo, Japan
| | - Minoru Tanabe
- Department of Hepatobiliary and Pancreatic SurgeryGraduate School of Medicine, Tokyo Medical and Dental University, Tokyo, Japan
| | - Shinji Tanaka
- Department of Molecular OncologyGraduate School of Medicine, Tokyo Medical and Dental University, Tokyo, Japan
- Department of Hepatobiliary and Pancreatic SurgeryGraduate School of Medicine, Tokyo Medical and Dental University, Tokyo, Japan
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11
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12
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Li Z, Zhao D, Xiang B, Li H. Structural and biochemical characterization of DAXX-ATRX interaction. Protein Cell 2018; 8:762-766. [PMID: 28875283 PMCID: PMC5636754 DOI: 10.1007/s13238-017-0463-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Affiliation(s)
- Zhuang Li
- College of Life Sciences, Peking University, Beijing, 100871, China.,MOE Key Laboratory of Protein Sciences, Tsinghua-Peking Joint Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, Department of Basic Medical Sciences, School of Medicine, Tsinghua University, Beijing, 100084, China
| | - Dan Zhao
- MOE Key Laboratory of Protein Sciences, Tsinghua-Peking Joint Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, Department of Basic Medical Sciences, School of Medicine, Tsinghua University, Beijing, 100084, China
| | - Bin Xiang
- College of Life Sciences, Peking University, Beijing, 100871, China.,MOE Key Laboratory of Protein Sciences, Tsinghua-Peking Joint Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, Department of Basic Medical Sciences, School of Medicine, Tsinghua University, Beijing, 100084, China
| | - Haitao Li
- MOE Key Laboratory of Protein Sciences, Tsinghua-Peking Joint Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, Department of Basic Medical Sciences, School of Medicine, Tsinghua University, Beijing, 100084, China.
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13
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Hoelper D, Huang H, Jain AY, Patel DJ, Lewis PW. Structural and mechanistic insights into ATRX-dependent and -independent functions of the histone chaperone DAXX. Nat Commun 2017; 8:1193. [PMID: 29084956 PMCID: PMC5662737 DOI: 10.1038/s41467-017-01206-y] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Accepted: 08/29/2017] [Indexed: 12/20/2022] Open
Abstract
The ATRX–DAXX histone chaperone complex incorporates the histone variant H3.3 at heterochromatic regions in a replication-independent manner. Here, we present a high-resolution x-ray crystal structure of an interaction surface between ATRX and DAXX. We use single amino acid substitutions in DAXX that abrogate formation of the complex to explore ATRX-dependent and ATRX-independent functions of DAXX. We find that the repression of specific murine endogenous retroviruses is dependent on DAXX, but not on ATRX. In support, we reveal the existence of two biochemically distinct DAXX-containing complexes: the ATRX–DAXX complex involved in gene repression and telomere chromatin structure, and a DAXX–SETDB1–KAP1–HDAC1 complex that represses endogenous retroviruses independently of ATRX and H3.3 incorporation into chromatin. We find that histone H3.3 stabilizes DAXX protein levels and can affect DAXX-regulated gene expression without incorporation into nucleosomes. Our study demonstrates a nucleosome-independent function for the H3.3 histone variant. The ATRX-DAXX histone chaperone complex incorporates H3.3 in heterochromatin in a replication-independent manner. Here, the authors present a high-resolution x-ray crystal structure of an interaction surface between ATRX and DAXX, and characterize ATRX-dependent and-independent functions of DAXX.
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Affiliation(s)
- Dominik Hoelper
- Department of Biomolecular Chemistry, School of Medicine and Public Health, University of Wisconsin, Madison, WI, 53706, USA.,Wisconsin Institute for Discovery, University of Wisconsin, Madison, WI, 53715, USA
| | - Hongda Huang
- Structural Biology Program, Memorial Sloan-Kettering Cancer Center, New York, NY, 10065, USA.,Department of Biology, South University of Science and Technology, Shenzhen, Guangdong, 518055, China
| | - Aayushi Y Jain
- Department of Biomolecular Chemistry, School of Medicine and Public Health, University of Wisconsin, Madison, WI, 53706, USA.,Wisconsin Institute for Discovery, University of Wisconsin, Madison, WI, 53715, USA
| | - Dinshaw J Patel
- Structural Biology Program, Memorial Sloan-Kettering Cancer Center, New York, NY, 10065, USA
| | - Peter W Lewis
- Department of Biomolecular Chemistry, School of Medicine and Public Health, University of Wisconsin, Madison, WI, 53706, USA. .,Wisconsin Institute for Discovery, University of Wisconsin, Madison, WI, 53715, USA.
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14
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Svadlenka J, Brazina J, Hanzlikova H, Cermak L, Andera L. Multifunctional adaptor protein Daxx interacts with chromatin-remodelling ATPase Brg1. Biochem Biophys Rep 2015; 5:246-252. [PMID: 28955830 PMCID: PMC5600331 DOI: 10.1016/j.bbrep.2015.12.012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Revised: 11/25/2015] [Accepted: 12/28/2015] [Indexed: 01/22/2023] Open
Abstract
Multifunctional adapter and chaperone protein Daxx participates in the regulation of a number of mainly transcription-related processes. Most notably in a complex with chromatin-remodelling ATPase ATRX, Daxx serves as a histone H3.3 chaperone at telomeric regions and certain genes. In this report we document that Daxx interacts with another chromatin-remodelling, ATPase Brg1. We confirm the Daxx-Brg1 association both in vitro and in cells and show that Daxx interacts with Brg1 in high-molecular-weight complexes. Ectopic co-expression of Daxx with Brg1 and PML could shift disperse nuclear localisation of Brg1 into PML bodies. Mapping the Daxx-Brg1 interaction revealed that Daxx preferentially binds the region between Brg1 N-terminal QLQ and HSA domains, but also weakly interacts with its C-terminal part. Brg1 interacted with both the central and N-terminal parts of Daxx. SiRNA-mediated down-regulation of Daxx in SW13 adrenal carcinoma cells markedly enhanced expression of Brg1-activated genes CD44 or SCEL, suggesting that Daxx either directly through Brg1 and/or indirectly via other factors is a negative regulator of their transcription. Our findings point to Brg1 as another chromatin-remodelling protein that might similarly, as ATRX, target Daxx to specific chromatin regions where it can carry out its chromatin- and transcription-regulating functions.
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Affiliation(s)
- Jan Svadlenka
- Institute of Molecular Genetics AS CR, Czech Republic
| | - Jan Brazina
- Institute of Molecular Genetics AS CR, Czech Republic
| | | | - Lukas Cermak
- Department of Pathology, New York University School of Medicine, New York, USA
| | - Ladislav Andera
- Institute of Molecular Genetics AS CR, Czech Republic.,Institute of Biotechnology AS CR, Prague, Czech Republic
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15
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Brazina J, Svadlenka J, Macurek L, Andera L, Hodny Z, Bartek J, Hanzlikova H. DNA damage-induced regulatory interplay between DAXX, p53, ATM kinase and Wip1 phosphatase. Cell Cycle 2015; 14:375-87. [PMID: 25659035 PMCID: PMC4353233 DOI: 10.4161/15384101.2014.988019] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Death domain-associated protein 6 (DAXX) is a histone chaperone, putative regulator of apoptosis and transcription, and candidate modulator of p53-mediated gene expression following DNA damage. DAXX becomes phosphorylated upon DNA damage, however regulation of this modification, and its relationship to p53 remain unclear. Here we show that in human cells exposed to ionizing radiation or genotoxic drugs etoposide and neocarzinostatin, DAXX became rapidly phosphorylated in an ATM kinase-dependent manner. Our deletion and site-directed mutagenesis experiments identified Serine 564 (S564) as the dominant ATM-targeted site of DAXX, and immunofluorescence experiments revealed localization of S564-phosphorylated DAXX to PML nuclear bodies. Furthermore, using a panel of human cell types, we identified the p53-regulated Wip1 protein phosphatase as a key negative regulator of DAXX phosphorylation at S564, both in vitro and in cells. Consistent with the emerging oncogenic role of Wip1, its DAXX-dephosphorylating impact was most apparent in cancer cell lines harboring gain-of-function mutant and/or overexpressed Wip1. Unexpectedly, while Wip1 depletion increased DAXX phosphorylation both before and after DNA damage and increased p53 stability and transcriptional activity, knock-down of DAXX impacted neither p53 stabilization nor p53-mediated expression of Gadd45a, Noxa, Mdm2, p21, Puma, Sesn2, Tigar or Wip1. Consistently, analyses of cells with genetic, TALEN-mediated DAXX deletion corroborated the notion that neither phosphorylated nor non-phosphorylated DAXX is required for p53-mediated gene expression upon DNA damage. Overall, we identify ATM kinase and Wip1 phosphatase as opposing regulators of DAXX-S564 phosphorylation, and propose that the role of DAXX phosphorylation and DAXX itself are independent of p53-mediated gene expression.
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Affiliation(s)
- Jan Brazina
- a Department of Cell Signaling and Apoptosis
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16
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DeNizio JE, Elsässer SJ, Black BE. DAXX co-folds with H3.3/H4 using high local stability conferred by the H3.3 variant recognition residues. Nucleic Acids Res 2014; 42:4318-31. [PMID: 24493739 PMCID: PMC3985662 DOI: 10.1093/nar/gku090] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2013] [Revised: 12/17/2013] [Accepted: 01/08/2014] [Indexed: 01/08/2023] Open
Abstract
Histone chaperones are a diverse class of proteins that facilitate chromatin assembly. Their ability to stabilize highly abundant histone proteins in the cellular environment prevents non-specific interactions and promotes nucleosome formation, but the various mechanisms for doing so are not well understood. We now focus on the dynamic features of the DAXX histone chaperone that have been elusive from previous structural studies. Using hydrogen/deuterium exchange coupled to mass spectrometry (H/DX-MS), we elucidate the concerted binding-folding of DAXX with histone variants H3.3/H4 and H3.2/H4 and find that high local stability at the variant-specific recognition residues rationalizes its known selectivity for H3.3. We show that the DAXX histone binding domain is largely disordered in solution and that formation of the H3.3/H4/DAXX complex induces folding and dramatic global stabilization of both histone and chaperone. Thus, DAXX uses a novel strategy as a molecular chaperone that paradoxically couples its own folding to substrate recognition and binding. Further, we propose a model for the chromatin assembly reaction it mediates, including a stepwise folding pathway that helps explain the fidelity of DAXX in associating with the H3.3 variant, despite an extensive and nearly identical binding surface on its counterparts, H3.1 and H3.2.
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Affiliation(s)
- Jamie E. DeNizio
- Department of Biochemistry and Biophysics, Graduate Program in Biochemistry and Molecular Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6059, USA and MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK
| | - Simon J. Elsässer
- Department of Biochemistry and Biophysics, Graduate Program in Biochemistry and Molecular Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6059, USA and MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK
| | - Ben E. Black
- Department of Biochemistry and Biophysics, Graduate Program in Biochemistry and Molecular Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6059, USA and MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK
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17
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Volodko N, Gordon M, Salla M, Ghazaleh HA, Baksh S. RASSF tumor suppressor gene family: Biological functions and regulation. FEBS Lett 2014; 588:2671-84. [DOI: 10.1016/j.febslet.2014.02.041] [Citation(s) in RCA: 92] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Revised: 02/25/2014] [Accepted: 02/25/2014] [Indexed: 01/22/2023]
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18
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Santiago A, Li D, Zhao LY, Godsey A, Liao D. p53 SUMOylation promotes its nuclear export by facilitating its release from the nuclear export receptor CRM1. Mol Biol Cell 2013; 24:2739-52. [PMID: 23825024 PMCID: PMC3756925 DOI: 10.1091/mbc.e12-10-0771] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Revised: 06/24/2013] [Accepted: 06/24/2013] [Indexed: 12/11/2022] Open
Abstract
Chromosomal region maintenance 1 (CRM1) mediates p53 nuclear export. Although p53 SUMOylation promotes its nuclear export, the underlying mechanism is unclear. Here we show that tethering of a small, ubiquitin-like modifier (SUMO) moiety to p53 markedly increases its cytoplasmic localization. SUMO attachment to p53 does not affect its oligomerization, suggesting that subunit dissociation required for exposing p53's nuclear export signal (NES) is unnecessary for p53 nuclear export. Surprisingly, SUMO-mediated p53 nuclear export depends on the SUMO-interacting motif (SIM)-binding pocket of SUMO-1. The CRM1 C-terminal domain lacking the NES-binding groove interacts with tetrameric p53, and the proper folding of the p53 core domain, rather than the presence of the N- or C-terminal tails, appears to be important for p53-CRM1 interaction. The CRM1 Huntington, EF3, a subunit of PP2A, and TOR1 9 (HEAT9) loop, which regulates GTP-binding nuclear protein Ran binding and cargo release, contains a prototypical SIM. Remarkably, disruption of this SIM in conjunction with a mutated SIM-binding groove of SUMO-1 markedly enhances the binding of CRM1 to p53-SUMO-1 and their accumulation in the nuclear pore complexes (NPCs), as well as their persistent association in the cytoplasm. We propose that SUMOylation of a CRM1 cargo such as p53 at the NPCs unlocks the HEAT9 loop of CRM1 to facilitate the disassembly of the transporting complex and cargo release to the cytoplasm.
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Affiliation(s)
- Aleixo Santiago
- Department of Anatomy and Cell Biology, UF Health Cancer Center, and UF Genetics Institute, University of Florida College of Medicine, Gainesville, FL 32610
| | - Dawei Li
- Department of Anatomy and Cell Biology, UF Health Cancer Center, and UF Genetics Institute, University of Florida College of Medicine, Gainesville, FL 32610
- Department of Urology, Qilu Hospital, Shandong University, Jinan 250012, Shandong, China
| | - Lisa Y. Zhao
- Department of Anatomy and Cell Biology, UF Health Cancer Center, and UF Genetics Institute, University of Florida College of Medicine, Gainesville, FL 32610
| | - Adam Godsey
- Department of Anatomy and Cell Biology, UF Health Cancer Center, and UF Genetics Institute, University of Florida College of Medicine, Gainesville, FL 32610
| | - Daiqing Liao
- Department of Anatomy and Cell Biology, UF Health Cancer Center, and UF Genetics Institute, University of Florida College of Medicine, Gainesville, FL 32610
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19
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Halder UC, Bhowmick R, Roy Mukherjee T, Nayak MK, Chawla-Sarkar M. Phosphorylation drives an apoptotic protein to activate antiapoptotic genes: paradigm of influenza A matrix 1 protein function. J Biol Chem 2013; 288:14554-14568. [PMID: 23548901 DOI: 10.1074/jbc.m112.447086] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
During infection, viral proteins target cellular pathways that regulate cellular innate immune responses and cell death. We demonstrate that influenza A virus matrix 1 protein (M1), an established proapoptotic protein, activates nuclear factor-κB member RelB-mediated survival genes (cIAP1, cIAP2, and cFLIP), a function that is linked with its nuclear translocation during early infection. Death domain-associated protein 6 (Daxx) is a transcription co-repressor of the RelB-responsive gene promoters. During influenza virus infection M1 binds to and stabilizes Daxx protein by preventing its ubiquitination and proteasomal degradation. Binding of M1 with Daxx through its Daxx binding motif prevents binding of RelB and Daxx, resulting in up-regulation of survival genes. This interaction also prevents promoter recruitment of DNA methyltransferases (Dnmt1 and Dnmt3a) and lowers CpG methylation of the survival gene promoters, leading to the activation of these genes. Thus, M1 prevents repressional function of Daxx during infection, thereby exerting a survival role. In addition to its nuclear localization signal, translocation of M1 to the nucleus depends on cellular kinase-mediated phosphorylation as the protein kinase C inhibitor calphostin C effectively down-regulates virus replication. The study reconciles the ambiguity of dual antagonistic function of viral protein and potentiates a possible target to limit virus infection.
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Affiliation(s)
- Umesh Chandra Halder
- Division of Virology, National Institute of Cholera and Enteric Diseases, P-33 C.I.T. Road, Scheme-XM, Beliaghata, Kolkata 700010, India
| | - Rahul Bhowmick
- Division of Virology, National Institute of Cholera and Enteric Diseases, P-33 C.I.T. Road, Scheme-XM, Beliaghata, Kolkata 700010, India
| | - Tapasi Roy Mukherjee
- Division of Virology, National Institute of Cholera and Enteric Diseases, P-33 C.I.T. Road, Scheme-XM, Beliaghata, Kolkata 700010, India
| | - Mukti Kant Nayak
- Department of Zoology, University of Calcutta, 35 Ballygunge Circular Road, Kolkata 700019, India
| | - Mamta Chawla-Sarkar
- Division of Virology, National Institute of Cholera and Enteric Diseases, P-33 C.I.T. Road, Scheme-XM, Beliaghata, Kolkata 700010, India.
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20
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Shalginskikh N, Poleshko A, Skalka AM, Katz RA. Retroviral DNA methylation and epigenetic repression are mediated by the antiviral host protein Daxx. J Virol 2013; 87:2137-50. [PMID: 23221555 PMCID: PMC3571491 DOI: 10.1128/jvi.02026-12] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2012] [Accepted: 11/28/2012] [Indexed: 12/23/2022] Open
Abstract
Integrated retroviral DNA is subject to epigenetic transcriptional silencing at different frequencies. This process is mediated by repressive DNA methylation and histone modifications on viral chromatin. However, the detailed mechanisms by which retroviral silencing is initiated and maintained are not well understood. Using a model system in which avian sarcoma virus (ASV) DNA is epigenetically repressed in mammalian cells, we previously found that a cellular scaffolding protein, Daxx, acts as an antiretroviral factor that promotes epigenetic repression through recruitment of histone deacetylases (HDACs). Here we show that human Daxx protein levels are increased in response to retroviral infection and that Daxx acts at the time of infection to initiate epigenetic repression. Consistent with a rapid and active antiviral epigenetic response, we found that repressive histone marks and long terminal repeat (LTR) DNA methylation could be detected within 12 h to 3 days postinfection, respectively. Daxx was also found to be required for long-term ASV silencing maintenance and full viral DNA methylation, and it was physically associated with both viral DNA and DNA methyltransferases (DNMTs). These findings support a model in which incoming retroviral protein-DNA complexes are detected by Daxx, and the integrated provirus is rapidly chromatinized and repressed by DNA methylation and histone modification as part of an antiviral response. These results uncover a possible direct and active antiviral mechanism by which DNMTs can be recruited to retroviral DNA.
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Affiliation(s)
- Natalia Shalginskikh
- Institute for Cancer Research, Fox Chase Cancer Center, Philadelphia, Pennsylvania, USA
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21
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RASSF Signalling and DNA Damage: Monitoring the Integrity of the Genome? Mol Biol Int 2012; 2012:141732. [PMID: 22577550 PMCID: PMC3337673 DOI: 10.1155/2012/141732] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2011] [Accepted: 01/27/2012] [Indexed: 12/14/2022] Open
Abstract
The RASSF family of proteins has been extensively studied in terms of their genetics, structure and function. One of the functions that has been increasingly studied is the role of the RASSF proteins in the DNA damage response. Surprisingly, this research, which encompasses both the classical and N-terminal RASSF proteins, has revealed an involvement of the RASSFs in oncogenic pathways as well as the more familiar tumour suppressor pathways usually associated with the RASSF family members. The most studied protein with respect to DNA damage is RASSF1A, which has been shown, not only to be activated by ATM, a major regulator of the DNA damage response, but also to bind to and activate a number of different pathways which all lead to and feedback from the guardian of the genome, p53. In this review we discuss the latest research linking the RASSF proteins to DNA damage signalling and maintenance of genomic integrity and look at how this knowledge is being utilised in the clinic to enhance the effectiveness of traditional cancer therapies such as radiotherapy.
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22
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Abstract
Current theories suggest that mitotic checkpoint proteins are essential for proper cellular response to taxanes, a widely-used family of chemotherapeutic compounds. We recently demonstrated that absence or depletion of protein Daxx increases cellular taxol (paclitaxel) resistance—a common trait of patients diagnosed with several malignancies, including breast cancer. Further investigation of Daxx-mediated taxol response revealed that Daxx is important for the proper timing of mitosis progression and cyclin B stability. Daxx interacts with mitotic checkpoint protein Rassf1 and partially co-localizes with this protein during mitosis. Rassf1/Daxx depletion or expression of Daxx binding domain of Rassf1 elevates cyclin B stability and increases taxol resistance in cells and mouse xenograft models. In breast cancer patients, we observed the inverse correlation between Daxx and clinical response to taxane-based chemotherapy. These data suggest that Daxx and Rassf1 define a mitotic stress checkpoint that enables cells to exit mitosis as micronucleated cells (and eventually die) when encountered with specific mitotic stress stimuli, including taxol. Surprisingly, depletion of Daxx or Rassf1 does not change activity of E3 ubiquitin ligase APC/C in in vitro settings, suggesting necessity of mitotic cellular environment for proper activation of this checkpoint. Daxx and Rassf1 may become useful predictive markers for the proper selection of patients for taxane chemotherapy.
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Escobar-Cabrera E, Okon M, Lau DKW, Dart CF, Bonvin AMJJ, McIntosh LP. Characterizing the N- and C-terminal Small ubiquitin-like modifier (SUMO)-interacting motifs of the scaffold protein DAXX. J Biol Chem 2011; 286:19816-29. [PMID: 21383010 DOI: 10.1074/jbc.m111.231647] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
DAXX is a scaffold protein with diverse roles that often depend upon binding SUMO via its N- and/or C-terminal SUMO-interacting motifs (SIM-N and SIM-C). Using NMR spectroscopy, we characterized the in vitro binding properties of peptide models of SIM-N and SIM-C to SUMO-1 and SUMO-2. In each case, binding was mediated by hydrophobic and electrostatic interactions and weakened with increasing ionic strength. Neither isolated SIM showed any significant paralog specificity, and the measured μM range K(D) values of SIM-N toward both SUMO-1 and SUMO-2 were ∼4-fold lower than those of SIM-C. Furthermore, SIM-N bound SUMO-1 predominantly in a parallel orientation, whereas SIM-C interconverted between parallel and antiparallel binding modes on an ms to μs time scale. The differences in affinities and binding modes are attributed to the differences in charged residues that flank the otherwise identical hydrophobic core sequences of the two SIMs. In addition, within its native context, SIM-N bound intramolecularly to the adjacent N-terminal helical bundle domain of DAXX, thus reducing its apparent affinity for SUMO. This behavior suggests a possible autoregulatory mechanism for DAXX. The interaction of a C-terminal fragment of DAXX with an N-terminal fragment of the sumoylated Ets1 transcription factor was mediated by SIM-C. Importantly, this interaction did not involve any direct contacts between DAXX and Ets1, but rather was derived from the non-covalent binding of SIM-C to SUMO-1, which in turn was covalently linked to the unstructured N-terminal segment of Ets1. These results provide insights into the binding mechanisms and hence biological roles of the DAXX SUMO-interacting motifs.
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Affiliation(s)
- Eric Escobar-Cabrera
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada
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