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Mohanraj L, Wolf H, Silvey S, Liu J, Toor A, Swift-Scanlan T. DNA Methylation Changes in Autologous Hematopoietic Stem Cell Transplant Patients. Biol Res Nurs 2023; 25:310-325. [PMID: 36321693 PMCID: PMC10236442 DOI: 10.1177/10998004221135628] [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] [Indexed: 11/07/2022]
Abstract
BACKGROUND Blood cancers may be potentially cured with hematopoietic stem cell transplantation (HCT); however, standard pre-assessments for transplant eligibility do not capture all contributing factors for transplant outcomes. Epigenetic biomarkers predict outcomes in various diseases. This pilot study aims to explore epigenetic changes (epigenetic age and differentially methylated genes) in patients before and after autologous HCT, that can serve as potential biomarkers to better predict HCT outcomes. METHODS This study used a prospective longitudinal study design to compare genome wide DNA methylation changes in 36 autologous HCT eligible patients recruited from the Cellular Immunotherapies and Transplant clinic at a designated National Cancer Center. RESULTS Genome-wide DNA methylation, measured by the Illumina Infinium Human Methylation 850K BeadChip, showed a significant difference in DNA methylation patterns post-HCT compared to pre-HCT. Compared to baseline levels of DNA methylation pre-HCT, 3358 CpG sites were hypo-methylated and 3687 were hyper-methylated. Identified differentially methylated positions overlapped with genes involved in hematopoiesis, blood cancers, inflammation and immune responses. Enrichment analyses showed significant alterations in biological processes such as immune response and cell structure organization, however no significant pathways were noted. Though participants had an advanced epigenetic age compared to chronologic age before and after HCT, both epigenetic age and accelerated age decreased post-HCT. CONCLUSION Epigenetic changes, both in epigenetic age and differentially methylated genes were observed in autologous HCT recipients, and should be explored as biomarkers to predict transplant outcomes after autologous HCT in larger, longitudinal studies.
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Affiliation(s)
- Lathika Mohanraj
- Department of Adult Health and Nursing
Systems, VCU School of Nursing, Richmond, VA, USA
| | - Hope Wolf
- Department of Human and Molecular Genetics, VCU School of Medicine, Richmond, VA, USA
| | - Scott Silvey
- Department of Biostatistics, VCU School of Medicine, Richmond, VA, USA
| | - Jinze Liu
- Department of Biostatistics, VCU School of Medicine, Richmond, VA, USA
| | - Amir Toor
- Department of Internal Medicine, VCU School of Medicine, Richmond, VA, USA
| | - Theresa Swift-Scanlan
- Endowed Professor and Director,
Biobehavioral Research Lab, VCU School of Nursing, Richmond, VA, USA
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DAXX ameliorates metabolic dysfunction in mice with diet-induced obesity by activating the AMP-activated protein kinase-related kinase MPK38/MELK. Biochem Biophys Res Commun 2021; 572:164-170. [PMID: 34365141 DOI: 10.1016/j.bbrc.2021.08.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Accepted: 08/02/2021] [Indexed: 11/21/2022]
Abstract
Death domain-associated protein (DAXX) is involved in the activation of adipocyte apoptosis and is downregulated in response to a high-fat diet (HFD), which implies that the inhibition of adipocyte apoptosis may cause obesity. However, the anti-obesity effects of DAXX in diet-induced obesity (DIO) remain to be characterized. Here, we identified DAXX as an interacting partner of murine protein serine-threonine kinase 38 (MPK38). This interaction was mediated by the C-terminal (amino acids 270-643) domain of MPK38 and the N-terminal (amino acids 1-440) domain of DAXX and was increased by diverse signals that activate ASK1/TGF-β/p53 signaling. MPK38 phosphorylated DAXX at Thr578. Wild-type DAXX, but not a DAXX T578A mutant, stimulated MPK38-dependent ASK1/TGF-β/p53 signaling by increasing the stability of MPK38 and complex formation between MPK38 and its downstream targets, such as ASK1, Smad3, and p53. This mechanism was also shown in MEF cells that were null (-/-) for DAXX. Furthermore, the adenovirally-mediated reinstatement of DAXX expression activated MPK38 and ameliorated diet-induced defects in glucose and lipid metabolism in mice. These results indicate that DAXX limits obesity-induced metabolic abnormalities in DIO mice by activating MPK38.
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Jing X, Ren D, Gao F, Chen Y, Wu X, Han Y, Han Q, Li L, Wang X, Tang W, Zhang Y. Gene deficiency or pharmacological inhibition of PDCD4-mediated FGR signaling protects against acute kidney injury. Acta Pharm Sin B 2021; 11:394-405. [PMID: 33643819 PMCID: PMC7893143 DOI: 10.1016/j.apsb.2020.10.024] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2020] [Revised: 09/23/2020] [Accepted: 10/13/2020] [Indexed: 12/28/2022] Open
Abstract
Recent studies have shown that programmed cell death 4 (PDCD4) modulates distinct signal transduction pathways in different pathological conditions. Despite acute and chronic immune responses elicited by ischemia contributing to the functional deterioration of the kidney, the contributions and mechanisms of PDCD4 in acute kidney injury (AKI) have remained unclear. Using two murine AKI models including renal ischemia/reperfusion injury (IRI) and cisplatin-induced AKI, we found that PDCD4 deficiency markedly ameliorated renal dysfunction and inflammatory responses in AKI mice. Consistently, upregulation of PDCD4 was also confirmed in the kidneys from patients with biopsy confirmed acute tubular necrosis from a retrospective cohort study. Moreover, we found that overexpression of Fgr, a member of the tyrosine kinase family, dramatically aggravated renal injury and counteracted the protective effects of PDCD4 deficiency in AKI mice. We discovered that FGR upregulated NOTCH1 expression through activating STAT3. Most importantly, we further found that systemic administration of ponatinib, a tyrosine kinase inhibitor, significantly ameliorated AKI in mice. In summary, we identified that PDCD4 served as an important regulator, at least in part, of FGR/NOTCH1-mediated tubular apoptosis and inflammation in AKI mice. Furthermore, our findings suggest that ponatinib-mediated pharmacologic targeting of this pathway had therapeutic potential for mitigating AKI.
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Affiliation(s)
- Xu Jing
- Department of Pharmacology, School of Basic Medical Science, Shandong University, Jinan 250012, China
- Department of Clinical Laboratory, the Second Hospital of Shandong University, Jinan 250033, China
| | - Dandan Ren
- Department of Pharmacology, School of Basic Medical Science, Shandong University, Jinan 250012, China
- Chengda Biology Co., Ltd., Shenyang 110179, China
| | - Fei Gao
- The Key Laboratory of Cardiovascular Remodeling and Function Research, Department of Cardiology, Qilu Hospital of Shandong University, Jinan 250012, China
| | - Ye Chen
- Department of Pharmacology, School of Basic Medical Science, Shandong University, Jinan 250012, China
| | - Xiao Wu
- The Key Laboratory of Cardiovascular Remodeling and Function Research, Department of Cardiology, Qilu Hospital of Shandong University, Jinan 250012, China
| | - Yue Han
- Department of Pharmacology, School of Basic Medical Science, Shandong University, Jinan 250012, China
| | - Qingsheng Han
- Department of Pharmacology, School of Basic Medical Science, Shandong University, Jinan 250012, China
| | - Liang Li
- Department of Pharmacology, School of Basic Medical Science, Shandong University, Jinan 250012, China
| | - Xiaojie Wang
- Department of Pharmacology, School of Basic Medical Science, Shandong University, Jinan 250012, China
| | - Wei Tang
- Department of Microbiology, School of Basic Medical Science, Shandong University, Jinan 250012, China
| | - Yan Zhang
- Department of Pharmacology, School of Basic Medical Science, Shandong University, Jinan 250012, China
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An integrated multi-omics approach identifies epigenetic alterations associated with Alzheimer's disease. Nat Genet 2020; 52:1024-1035. [PMID: 32989324 PMCID: PMC8098004 DOI: 10.1038/s41588-020-0696-0] [Citation(s) in RCA: 186] [Impact Index Per Article: 46.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2019] [Accepted: 08/20/2020] [Indexed: 12/19/2022]
Abstract
Protein aggregation is the hallmark of neurodegeneration but the molecular mechanisms underlying late-onset Alzheimer’s disease (AD) remain unclear. Here we integrated transcriptomic, proteomic and epigenomic analyses of post-mortem human brains to identify molecular pathways involved in AD. RNA-seq analysis revealed upregulation of transcription- and chromatin-related genes, including the histone acetyltransferases for H3K27ac and H3K9ac. An unbiased proteomic screening singled out H3K27ac and H3K9ac as main enrichments specific to AD. In turn, epigenomic profiling revealed gains of H3K27ac and H3K9ac linked to transcription, chromatin, and disease pathways in AD. Increasing genome-wide H3K27ac and H3K9ac in a fly model of AD exacerbated amyloid-β42-driven neurodegeneration. Together, these findings suggest that AD involves a reconfiguration of the epigenome, where H3K27ac and H3K9ac impact disease pathways by dysregulating transcription- and chromatin-gene feedback loops. The identification of this process highlights potential epigenetic strategies for early-stage disease treatment.
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Abstract
The tumor suppressor phosphatase and tension homolog (PTEN) is frequently mutated in human cancers, and it functions in multiple ways to safeguard cells from tumorigenesis. In the cytoplasm, PTEN antagonizes the PI3K/AKT pathway and suppresses cellular proliferation and survival. In the nucleus, PTEN is indispensable for the maintenance of genomic stability. In addition, PTEN loss leads to extensive changes in gene expression at the transcriptional level. The linker histone H1, generally considered as a transcriptional repressor, binds to the nucleosome to form a structure named the chromatosome. The dynamics between H1 and chromatin play an important role in determining gene expression. Here, we summarize the current understanding of roles of PTEN in controlling chromatin dynamics and global gene expression, which is crucial function of nuclear PTEN. We will also introduce the recent discovery of the PTEN family members and their functions.
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Affiliation(s)
- Jingyi Yang
- Institute of Systems Biomedicine, Beijing Key Laboratory of Tumor Systems Biology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing 100191, China
| | - Yuxin Yin
- Institute of Systems Biomedicine, Beijing Key Laboratory of Tumor Systems Biology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing 100191, China.,Peking-Tsinghua Center for Life Sciences, Peking University Health Science Center, Beijing 100191, China
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Liu SB, Lin XP, Xu Y, Shen ZF, Pan WW. DAXX promotes ovarian cancer ascites cell proliferation and migration by activating the ERK signaling pathway. J Ovarian Res 2018; 11:90. [PMID: 30336783 PMCID: PMC6193355 DOI: 10.1186/s13048-018-0462-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Accepted: 10/03/2018] [Indexed: 01/12/2023] Open
Abstract
BACKGROUND The death-domain-associated protein (DAXX) was originally identified as a protein that binds to the transmembrane death receptor FAS and enhances both FAS-induced and transforming growth factor-β-dependent apoptosis. In a previous study, we found that nude mice injected with DAXX-overexpressing cells (ES-2-DAXX) accumulated large concentrations of first-generation ascites cells (I ascites cells). The role of DAXX in the development of ascites is unknown. The aim of this study was to analyze the effect of DAXX on proliferation and migration of ascites cells in ovarian cancer in vitro and in vivo. METHODS Nude mice were housed in cages with a 14:10 h light:dark cycle; water and food were provided ad libitum. ES-2-DAXX cells (1×106) were injected intraperitoneally into athymic nude mice (8-week-old female mice). After 4 weeks, I ascites cells were collected. The I ascites cells were injected intraperitoneally into athymic nude mice (8-week-old female mice). After 4 weeks, II ascites cells were collected and cultured. Ascites cell survival, migration, and colony formation were measured using colony formation and cell growth assays. Immunofluorescent staining revealed the co-localization of DAXX and promyelocytic leukemia protein (PML) in ascites cell nuclei. Western blotting and immunohistochemistry showed that extracellular signal-related kinase (p-ERK) 1/2 and CEBP-β were highly expressed in tumor tissues formed by II ascites cells. Through immunoprecipitation, we also found that DAXX can interact with CEBP-β. RESULTS DAXX enhanced ascites cell survival, migration, and colony formation. DAXX and PML nuclear foci dramatically increased in a passage-dependent manner in ascites cells, DAXX promoted the tumor growth of ascites cells in vivo, increased ascites cell proliferation in vivo, and enhanced ascites cell survival and migration by activating the ERK signalling pathway and integrating with CEBP-β. CONCLUSIONS DAXX can interact with CEBP-β. DAXX can induce ovarian cancer ascites formation by activating the ERK signal pathway and binding to CEBP-β.
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Affiliation(s)
- Sheng-Bing Liu
- College of Medicine, Jiaxing University, Jiaxing, 314001, China
| | - Xue-Ping Lin
- College of Medicine, Jiaxing University, Jiaxing, 314001, China
| | - Ying Xu
- College of Medicine, Jiaxing University, Jiaxing, 314001, China
| | - Zhong-Fei Shen
- College of Medicine, Jiaxing University, Jiaxing, 314001, China
| | - Wei-Wei Pan
- College of Medicine, Jiaxing University, Jiaxing, 314001, China.
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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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Liu SB, Shen ZF, Guo YJ, Cao LX, Xu Y. PML silencing inhibits cell proliferation and induces DNA damage in cultured ovarian cancer cells. Biomed Rep 2017; 7:29-35. [PMID: 28685056 PMCID: PMC5492820 DOI: 10.3892/br.2017.919] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Accepted: 05/17/2017] [Indexed: 01/03/2023] Open
Abstract
The promyelocytic leukemia (PML) gene is a tumor suppressor gene. It was first identified in acute promyelocytic leukemia, in which it is fused to retinoic acid receptor α by the (15;17) chromosomal translocation. The function of the PML protein is frequently lost or aberrant in human solid tumors. In human ovarian carcinoma tissue, PML detected by immunohistochemistry was highly expressed. A PML-silencing vector, pSRG-shPml, was constructed and used to transfect human ovarian cancer cells. Cells were cultured and selected with puromycin for 10–15 days, and then the PML mRNA expression levels were detected by RT-qPCR and immunofluorescence. Proliferation and clone number of PML-depleted cells were detected using MTT assay and colony-forming assay. The protein expression associated with DNA damage and apoptosis was assessed in PML-depleted cells using western blot analysis and immunofluorescence. The results showed that PML was highly expressed in human ovarian tissue. The proliferation and colony formation of ovarian cancer cells were significantly inhibited after PML was depleted. Western blot analysis and immunofluorescence revealed that p-H2AX and cleaved caspase-3 expression significantly increased after PML silencing. PML was located in the nucleus, and it formed foci after X-ray irradiation. PML foci increased significantly with increasing irradiation doses.
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Affiliation(s)
- Sheng-Bing Liu
- College of Medicine, Jiaxing University, Jiaxing, Zhejiang 314001, P.R. China
| | - Zhong-Fei Shen
- College of Medicine, Jiaxing University, Jiaxing, Zhejiang 314001, P.R. China
| | - Yan-Jun Guo
- College of Medicine, Jiaxing University, Jiaxing, Zhejiang 314001, P.R. China
| | - Li-Xian Cao
- College of Medicine, Jiaxing University, Jiaxing, Zhejiang 314001, P.R. China
| | - Ying Xu
- College of Medicine, Jiaxing University, Jiaxing, Zhejiang 314001, P.R. China
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PTEN regulates glioblastoma oncogenesis through chromatin-associated complexes of DAXX and histone H3.3. Nat Commun 2017; 8:15223. [PMID: 28497778 PMCID: PMC5437297 DOI: 10.1038/ncomms15223] [Citation(s) in RCA: 74] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Accepted: 03/10/2017] [Indexed: 01/05/2023] Open
Abstract
Glioblastoma (GBM) is the most lethal type of human brain cancer, where deletions and mutations in the tumour suppressor gene PTEN (phosphatase and tensin homolog) are frequent events and are associated with therapeutic resistance. Herein, we report a novel chromatin-associated function of PTEN in complex with the histone chaperone DAXX and the histone variant H3.3. We show that PTEN interacts with DAXX and, in turn PTEN directly regulates oncogene expression by modulating DAXX-H3.3 association on the chromatin, independently of PTEN enzymatic activity. Furthermore, DAXX inhibition specifically suppresses tumour growth and improves the survival of orthotopically engrafted mice implanted with human PTEN-deficient glioma samples, associated with global H3.3 genomic distribution changes leading to upregulation of tumour suppressor genes and downregulation of oncogenes. Moreover, DAXX expression anti-correlates with PTEN expression in GBM patient samples. Since loss of chromosome 10 and PTEN are common events in cancer, this synthetic growth defect mediated by DAXX suppression represents a therapeutic opportunity to inhibit tumorigenesis specifically in the context of PTEN deletion. PTEN mutations are frequent in glioblastoma and often are associated with therapeutic resistance. Here, the authors demonstrate that PTEN regulates gene expression at the chromatin level by interacting with the histone chaperone DAXX and H3.3, and that DAXX inhibition inhibits PTEN-deficient GBM growth in vivo.
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10
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Pulido-Salgado M, Vidal-Taboada JM, Saura J. C/EBPβ and C/EBPδ transcription factors: Basic biology and roles in the CNS. Prog Neurobiol 2015; 132:1-33. [PMID: 26143335 DOI: 10.1016/j.pneurobio.2015.06.003] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2015] [Revised: 05/08/2015] [Accepted: 06/16/2015] [Indexed: 02/01/2023]
Abstract
CCAAT/enhancer binding protein (C/EBP) β and C/EBPδ are transcription factors of the basic-leucine zipper class which share phylogenetic, structural and functional features. In this review we first describe in depth their basic molecular biology which includes fascinating aspects such as the regulated use of alternative initiation codons in the C/EBPβ mRNA. The physical interactions with multiple transcription factors which greatly opens the number of potentially regulated genes or the presence of at least five different types of post-translational modifications are also remarkable molecular mechanisms that modulate C/EBPβ and C/EBPδ function. In the second part, we review the present knowledge on the localization, expression changes and physiological roles of C/EBPβ and C/EBPδ in neurons, astrocytes and microglia. We conclude that C/EBPβ and C/EBPδ share two unique features related to their role in the CNS: whereas in neurons they participate in memory formation and synaptic plasticity, in glial cells they regulate the pro-inflammatory program. Because of their role in neuroinflammation, C/EBPβ and C/EBPδ in microglia are potential targets for treatment of neurodegenerative disorders. Any strategy to reduce C/EBPβ and C/EBPδ activity in neuroinflammation needs to take into account its potential side-effects in neurons. Therefore, cell-specific treatments will be required for the successful application of this strategy.
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Affiliation(s)
- Marta Pulido-Salgado
- Biochemistry and Molecular Biology Unit, School of Medicine, University of Barcelona, IDIBAPS, Casanova 143, planta 3, 08036 Barcelona, Spain
| | - Jose M Vidal-Taboada
- Biochemistry and Molecular Biology Unit, School of Medicine, University of Barcelona, IDIBAPS, Casanova 143, planta 3, 08036 Barcelona, Spain
| | - Josep Saura
- Biochemistry and Molecular Biology Unit, School of Medicine, University of Barcelona, IDIBAPS, Casanova 143, planta 3, 08036 Barcelona, Spain.
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Pan WW, Yi FP, Cao LX, Liu XM, Shen ZF, Bu YQ, Xu Y, Fan HY, Song FZ. DAXX silencing suppresses mouse ovarian surface epithelial cell growth by inducing senescence and DNA damage. Gene 2013; 526:287-94. [DOI: 10.1016/j.gene.2013.03.103] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2012] [Revised: 02/02/2013] [Accepted: 03/16/2013] [Indexed: 01/08/2023]
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12
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Pan WW, Zhou JJ, Liu XM, Xu Y, Guo LJ, Yu C, Shi QH, Fan HY. Death domain-associated protein DAXX promotes ovarian cancer development and chemoresistance. J Biol Chem 2013; 288:13620-30. [PMID: 23539629 DOI: 10.1074/jbc.m112.446369] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
BACKGROUND The role of DAXX in ovarian cancer development and metastasis has not been investigated before now. RESULTS Overexpression of DAXX enhanced ovarian cancer cell proliferation, colony formation, and migration, whereas Daxx depletion had the opposite effects. CONCLUSION DAXX promotes ovarian cancer cell proliferation and chemoresistance. SIGNIFICANCE ModulatingDAXXmay be an effective strategy for preventing the recurrence and chemoresistance of ovarian cancers. Understanding the genes involved in apoptosis and DNA damage responses may improve therapeutic strategies for ovarian cancer. The death domain-associated protein DAXX can be either a pro-apoptotic or an anti-apoptotic factor, depending on the cell type and context. In this study, we found that DAXX was highly expressed in human ovarian surface epithelial tumors but not in granulosa cell tumors. In cultured ovarian cancer cells, DAXX interacted with promyelocytic leukemia protein (PML) and localized to subnuclear domains (so-called PML nuclear bodies). A role for DAXX in ovarian cancer cell proliferation, metastasis, and radio/chemoresistance was examined. Overexpression of DAXX enhanced multiple ovarian cancer cell lines' proliferation, colony formation, and migration, whereas Daxx depletion by RNA interference had the opposite effects. When transplanted into nude mice, ovarian cancer cells that overexpressed DAXX displayed enhanced tumorigenesis capability in vivo, whereas Daxx depletion inhibited tumor development. Importantly, Daxx induced tumorigenic transformation of normal ovarian surface epithelial cells. Daxx also protected ovarian cancer cells against x-irradiation- and chemotherapy-induced DNA damage by interacting with PML. Taken together, our results suggest that DAXX is a novel ovarian cancer oncogene that promotes ovarian cancer cell proliferation and chemoresistance in ovarian cancer cells. Thus, modulating DAXX-PML nuclear body activity may be an effective strategy for preventing the recurrence and chemoresistance of ovarian cancers.
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Affiliation(s)
- Wei-Wei Pan
- Life Sciences Institute, Zhejiang University, Hangzhou, 310058, China
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13
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Li J, Gu L, Zhang H, Liu T, Tian D, Zhou M, Zhou S. Berberine represses DAXX gene transcription and induces cancer cell apoptosis. J Transl Med 2013; 93:354-64. [PMID: 23295648 PMCID: PMC3961588 DOI: 10.1038/labinvest.2012.172] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Death-domain-associated protein (DAXX) is a multifunctional protein that regulates a wide range of cellular signaling pathways for both cell survival and apoptosis. Regulation of DAXX gene expression remains largely obscure. We recently reported that berberine (BBR), a natural product derived from a plant used in Chinese herbal medicine, downregulates DAXX expression at the transcriptional level. Here, we further investigate the mechanisms underlying the transcriptional suppression of DAXX by BBR. By analyzing and mapping the putative DAXX gene promoter, we identified the core promoter region (from -161 to -1), which contains consensus sequences for the transcriptional factors Sp1 and Ets1. We confirmed that Sp1 and Ets1 bound to the core promoter region of DAXX and stimulated DAXX transcriptional activity. In contrast, BBR bound to the DAXX core promoter region and suppressed its transcriptional activity. Following studies demonstrated a possible mechanism that BBR inhibited the DAXX promoter activity through blocking or disrupting the association of Sp1 or Ets1 and their consensus sequences in the promoter. Downregulation of DAXX by BBR resulted in inhibition of MDM2 and subsequently, activation of p53, leading to cancer cell death. Our results reveal a novel possible mechanism: by competitively binding to the Sp1 and Ets1 consensus sequences, BBR inhibits the transcription of DAXX, thus inducing cancer cell apoptosis through a p53-dependent pathway.
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Affiliation(s)
- Jiansha Li
- Institute of Pathology, Tongji hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Lubing Gu
- Departments of Pediatrics, Aflac Center and Blood Disorders Center, Emory University School of Medicine, Atlanta, GA, USA
| | - Hailong Zhang
- Departments of Pediatrics, Aflac Center and Blood Disorders Center, Emory University School of Medicine, Atlanta, GA, USA
| | - Tao Liu
- Departments of Pediatrics, Aflac Center and Blood Disorders Center, Emory University School of Medicine, Atlanta, GA, USA
| | - Dan Tian
- Departments of Pediatrics, Aflac Center and Blood Disorders Center, Emory University School of Medicine, Atlanta, GA, USA
| | - Muxiang Zhou
- Departments of Pediatrics, Aflac Center and Blood Disorders Center, Emory University School of Medicine, Atlanta, GA, USA
| | - Sheng Zhou
- Institute of Pathology, Tongji hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
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Kumar N, Wethkamp N, Waters LC, Carr MD, Klempnauer KH. Tumor suppressor protein Pdcd4 interacts with Daxx and modulates the stability of Daxx and the Hipk2-dependent phosphorylation of p53 at serine 46. Oncogenesis 2013; 2:e37. [PMID: 23536002 PMCID: PMC3564021 DOI: 10.1038/oncsis.2012.37] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The tumor suppressor protein Pdcd4 is a nuclear/cytoplasmic shuttling protein that has been implicated in the development of several types of human cancer. In the nucleus, Pdcd4 affects the transcription of specific genes by modulating the activity of several transcription factors. We have identified the Daxx protein as a novel interaction partner of Pdcd4. Daxx is a scaffold protein with roles in diverse processes, including transcriptional regulation, DNA-damage signaling, apoptosis and chromatin remodeling. We show that the interaction of both proteins is mediated by the N-terminal domain of Pdcd4 and the central part of Daxx, and that binding to Pdcd4 stimulates the degradation of Daxx, presumably by disrupting the interaction of Daxx with the de-ubiquitinylating enzyme Hausp. Daxx has previously been shown to serve as a scaffold for protein kinase Hipk2 and tumor suppressor protein p53 and to stimulate the phosphorylation of p53 at serine 46 (Ser-46) in response to genotoxic stress. We show that Pdcd4 also disrupts the Daxx–Hipk2 interaction and inhibits the phosphorylation of p53. We also show that ultraviolet irradiation decreases the expression of Pdcd4. Taken together, our results support a model in which Pdcd4 serves to suppress the phosphorylation of p53 in the absence of DNA damage, while the suppressive effect of Pdcd4 is abrogated after DNA damage owing to the decrease of Pdcd4. Overall, our data demonstrate that Pdcd4 is a novel modulator of Daxx function and provide evidence for a role of Pdcd4 in restraining p53 activity in unstressed cells.
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Affiliation(s)
- N Kumar
- 1] Institut für Biochemie, Westfälische-Wilhelms-Universität Münster, Münster, Germany [2] Graduate School of Chemistry (GSC-MS), Westfälische-Wilhelms-Universität Münster, Germany
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15
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Zhang H, He J, Li J, Tian D, Gu L, Zhou M. Methylation of RASSF1A gene promoter is regulated by p53 and DAXX. FASEB J 2012; 27:232-42. [PMID: 23038753 DOI: 10.1096/fj.12-215491] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Inactivation of the tumor suppressor Ras-association domain family 1 isoform A (RASSF1A) due to epigenetic silencing occurs in a variety of human cancers, and still largely unknown are the regulators and mechanisms underlying RASSF1A gene promoter methylation. Herein, we report that this methylation is regulated by p53 and death-associated protein 6 (DAXX) in acute lymphoblastic leukemia (ALL). We found that p53 bound to the RASSF1A promoter, recruiting DAXX as well as DNA methyltransferase 1 (DNMT1) for DNA methylation, which subsequently resulted in inactivation of RASSF1A in wild-type p53 ALL cells. Although the presence of p53 was required for the recruitment of DAXX and DNMT1 to the RASSF1A promoter, fluctuation in p53 protein levels did not affect the rates of RASSF1A methylation. Conversely, methylation of RASSF1A promoter was critically controlled by DAXX, as the enforced overexpression of DAXX led to enhanced RASSF1A promoter methylation, whereas inhibition of DAXX reduced RASSF1A methylation. Interestingly, we found that the p53/DAXX-mediated RASSF1A methylation regulated murine double minute 2 (MDM2) protein stability in ALL. Our results reveal a novel function for p53 in the methylation of RASSF1A promoter by its interaction with DAXX. Discovery of this mechanism provides new insight into the interactions among the tumor-related factors p53, RASSF1A, DAXX, and MDM2 in cancer pathogenesis.
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Affiliation(s)
- Hailong Zhang
- Division of Hematology/Oncology, Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia 30322, USA
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16
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Regulation of C/EBPβ and resulting functions in cells of the monocytic lineage. Cell Signal 2012; 24:1287-96. [DOI: 10.1016/j.cellsig.2012.02.007] [Citation(s) in RCA: 120] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2012] [Accepted: 02/14/2012] [Indexed: 01/10/2023]
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17
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Transcriptional activation of the adenoviral genome is mediated by capsid protein VI. PLoS Pathog 2012; 8:e1002549. [PMID: 22427750 PMCID: PMC3303589 DOI: 10.1371/journal.ppat.1002549] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2011] [Accepted: 01/10/2012] [Indexed: 12/12/2022] Open
Abstract
Gene expression of DNA viruses requires nuclear import of the viral genome. Human
Adenoviruses (Ads), like most DNA viruses, encode factors within early
transcription units promoting their own gene expression and counteracting
cellular antiviral defense mechanisms. The cellular transcriptional repressor
Daxx prevents viral gene expression through the assembly of repressive chromatin
remodeling complexes targeting incoming viral genomes. However, it has remained
unclear how initial transcriptional activation of the adenoviral genome is
achieved. Here we show that Daxx mediated repression of the immediate early Ad
E1A promoter is efficiently counteracted by the capsid protein VI. This requires
a conserved PPxY motif in protein VI. Capsid proteins from other DNA viruses
were also shown to activate the Ad E1A promoter independent of Ad gene
expression and support virus replication. Our results show how Ad entry is
connected to transcriptional activation of their genome in the nucleus. Our data
further suggest a common principle for genome activation of DNA viruses by
counteracting Daxx related repressive mechanisms through virion proteins. To initiate infection, DNA viruses deliver their genome to the nucleus and
express viral genes required for genome replication. Efficient transport is
achieved by packing the viral genome as a condensed, transcriptionally inactive
nucleo-protein complex. However, for most DNA viruses, including Adenoviruses
(Ads), it remains unclear how the viral genome is decondensed and how
transcription is initiated inside the nucleus. Cells control unwanted gene
expression by chromatin modification mediated through transcriptionally
repressive complexes. A key factor in repressive complex assemblies is the
transcriptional repressor Daxx. The Ad structural capsid protein VI is required
for endosomal escape and nuclear transport. Here we show that protein VI also
activates the Ad E1A promoter to initiate Ad gene expression. This is achieved
through the removal of Daxx repression from the E1A promoter, which requires a
conserved ubiquitin ligase interacting motif (PPxY-motif) in protein VI. We
further show that capsid proteins from other unrelated DNA viruses also activate
the Ad E1A promoter and support Ad replication by counteracting Daxx repression,
functionally replacing protein VI. Our data suggest that reversal of Daxx
repression by virion proteins is a widespread mechanism among DNA viruses that
is not restricted to a single virus family.
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18
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Lan HC, Wu CF, Shih HM, Chung BC. Death-associated protein 6 (Daxx) mediates cAMP-dependent stimulation of Cyp11a1 (P450scc) transcription. J Biol Chem 2011; 287:5910-6. [PMID: 22199361 DOI: 10.1074/jbc.m111.307603] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
SF-1 is a key transcription factor for all steroidogenic genes. It up-regulates the expression of the steroidogenic Cyp11a1 gene in the adrenal in a pathway stimulated by cAMP through HIPK3-mediated JNK/c-Jun phosphorylation. In the present study, we have investigated the factors mediating cAMP-dependent HIPK3 action to potentiate the activity of SF-1 for Cyp11a1 transcription in mouse adrenocortical Y1 cells. We found Daxx, a HIPK kinase substrate in the apoptosis pathway, was phosphorylated by HIPK3 at Ser-669 in response to cAMP stimulation. Daxx participated in SF-1-dependent Cyp11a1 expression as shown by experiments involving both overexpression and down-regulation via a dominant negative Daxx mutant. The S669A mutant of Daxx, which could not be phosphorylated by HIPK3, lost the ability to potentiate SF-1 activity for Cyp11a1 expression. The enhancement of SF-1 activity by Daxx required JNK and c-Jun phosphorylation. Thus, Daxx functioned as a signal transducer linking cAMP-stimulated HIPK3 activity with JNK/c-Jun phosphorylation and SF-1-dependent Cyp11a1 transcription for steroid synthesis.
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Affiliation(s)
- Hsin-Chieh Lan
- Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan
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19
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Wedeken L, Singh P, Klempnauer KH. Tumor suppressor protein Pdcd4 inhibits translation of p53 mRNA. J Biol Chem 2011; 286:42855-62. [PMID: 22033922 DOI: 10.1074/jbc.m111.269456] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
The tumor suppressor protein Pdcd4 is thought to suppress translation of mRNAs containing structured 5'-UTRs by interacting with translation initiation factor eIF4A and inhibiting its helicase activity. However, natural target mRNAs regulated by Pdcd4 so far are mostly unknown. Here, we identified p53 mRNA as a translational target of Pdcd4. We found that Pdcd4 is associated with p53 mRNA and suppresses its translation. The inhibitory effect of Pdcd4 on the translation of p53 mRNA depends on the ability of Pdcd4 to interact with eIF4A and is mediated by the 5'-UTR of p53 mRNA, which is able to form a stable stem-loop structure. We show that treatment of cells with DNA-damaging agents decreases the expression of Pdcd4. This suggests that translational suppression by Pdcd4 plays a role in maintaining a low level of p53 in unstressed cells and that this suppression is abrogated due to low levels of Pdcd4 after DNA damage. Overall, our work demonstrates for the first time that Pdcd4 is directly involved in translational suppression of a natural mRNA with a 5'-structured UTR and provides novel insight into the translational control of p53 expression.
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Affiliation(s)
- Lena Wedeken
- Institut für Biochemie, Westfälische-Wilhelms-Universität Münster, D-48149 Münster, Germany
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20
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Wethkamp N, Hanenberg H, Funke S, Suschek CV, Wetzel W, Heikaus S, Grinstein E, Ramp U, Engers R, Gabbert HE, Mahotka C. Daxx-beta and Daxx-gamma, two novel splice variants of the transcriptional co-repressor Daxx. J Biol Chem 2011; 286:19576-88. [PMID: 21482821 DOI: 10.1074/jbc.m110.196311] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Daxx is involved in transcriptional control and apoptosis. It comprises several domains, including a regulatory C terminus that is responsible for the interaction with numerous proteins such as p53, promyelocytic leukemia protein (PML), and Hsp27. Here, we describe the identification and characterization of two novel variants of Daxx termed Daxx-β and Daxx-γ, which are generated by alternative splicing. Alternative splicing results in a truncated regulatory C terminus in both proteins. As a consequence, Daxx-β and Daxx-γ show a markedly decreased affinity to PML, which in turn is associated with a different subnuclear localization of these proteins compared with Daxx. Although Daxx is localized mainly in PML-oncogenic domains (PODs) Daxx-β and Daxx-γ display a distinct distribution pattern. Furthermore, Daxx-β and Daxx-γ show a decreased affinity to p53 also due to the truncated C terminus. We provide evidence that the p53 recruitment into PODs is Daxx isoform-dependent. The decreased affinity of Daxx-β/-γ to p53 and PML results in a diffuse localization of p53 throughout the nucleus. In contrast to Daxx, Daxx-β and Daxx-γ are unable to repress p53-mediated transcription. Therefore, alternative splicing of Daxx might indicate an additional level in the cellular apoptosis network.
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Affiliation(s)
- Nils Wethkamp
- Institute of Pathology, Heinrich Heine University, University Hospital, Medical Faculty, Düsseldorf, Germany
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21
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Muromoto R, Kuroda M, Togi S, Sekine Y, Nanbo A, Shimoda K, Oritani K, Matsuda T. Functional involvement of Daxx in gp130-mediated cell growth and survival in BaF3 cells. Eur J Immunol 2010; 40:3570-80. [PMID: 21108476 DOI: 10.1002/eji.201040688] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2010] [Revised: 08/02/2010] [Accepted: 09/02/2010] [Indexed: 01/05/2023]
Abstract
Death domain-associated protein (Daxx) is a multifunctional protein that modulates both cell death and transcription. Several recent studies have indicated that Daxx is a mediator of lymphocyte death and/or growth suppression, although the detailed mechanism is unclear. Previously, we reported that Daxx suppresses IL-6 family cytokine-induced gene expression by interacting with STAT3. STAT3 is important for the growth and survival of lymphocytes; therefore, we here examined the role of Daxx in the gp130/STAT3-dependent cell growth/survival signals. We found that Daxx suppresses the gp130/STAT3-dependent cell growth and that Daxx endogenously interacts with STAT3 and inhibits the DNA-binding activity of STAT3. Moreover, small-interfering RNA-mediated knockdown of Daxx enhanced the expression of STAT3-target genes and accelerated the STAT3-mediated cell cycle progression. In addition, knockdown of Daxx-attenuated lactate dehydrogenase leakage from cells, indicating that Daxx positively regulates cell death during gp130/STAT3-mediated cell proliferation. Notably, Daxx specifically suppressed the levels of Bcl2 mRNA and protein, even in cytokine-unstimulated cells, indicating that Daxx regulates Bcl2 expression independently of activated STAT3. These results suggest that Daxx suppresses gp130-mediated cell growth and survival by two independent mechanisms: inhibition of STAT3-induced transcription and down-regulation of Bcl2 expression.
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Affiliation(s)
- Ryuta Muromoto
- Department of Immunology, Graduate School of Pharmaceutical Sciences, Hokkaido University, Kita-Ku, Sapporo, Japan
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22
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Zhang J, Hu YZ, Xueli L, Li S, Wang M, Kong X, Li T, Shen P, Ma Y. The inhibition of CMV promoter by heat shock factor 4b is regulated by Daxx. Int J Biochem Cell Biol 2010; 42:1698-707. [PMID: 20620219 DOI: 10.1016/j.biocel.2010.06.024] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2010] [Revised: 06/13/2010] [Accepted: 06/30/2010] [Indexed: 11/18/2022]
Abstract
Heat shock factor 4 (Hsf4b) has been identified as a novel cataractogenic protein whose mutation has been closely associated with hereditary cataracts in humans and animals. It acts both as a transcription activator and a transcription inhibitor in the regulation of its downstream targets during lens development. However, the signaling factors that regulate Hsf4b transcription activity are still not completely defined. Here, we found that Hsf4b, not Hsf4a (another isoform of Hsf4), acts as the inhibitor of CMV promoter as well as the activator of Hsp25 in the Hsf4-/- mouse lens epithelial cell line (mLEC/hsf4-/-). Hsf4b inhibits CMV-promoter activity by directly binding to TTCC (HSE motif) at 173-176bps in the CMV promoter. The phosphorylation of Hsf4b/S299 in the PDSM motif, which is absent in Hsf4a, participates in the negative regulation of the CMV promoter. The transcriptional inhibition of Hsf4b is associated with transcriptional inhibitor Daxx. Hsf4b can interact and co-localize with Daxx in the nucleus, and their association is regulated by the phosphorylation of Hsf4b/S299. In addition, we found that Hsf4a and Hsf1 were also associated with Daxx. However, in contrast to activating Hsf1, Daxx can repress Hsf4b-induced expression of Hsp25 in the mLEC/hsf4-/- cell line. Our results demonstrate that the transcription-inhibitory function of Hsf4b is regulated by the phosphorylation of Hsf4b/S299 and phosphorylation-dependent association with Daxx.
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Affiliation(s)
- Jun Zhang
- Key Laboratory of Molecular and Cellular Immunology, Henan University School of Medicine, Kaifeng, China
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23
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Tang J, Qu L, Pang M, Yang X. Daxx is reciprocally regulated by Mdm2 and Hausp. Biochem Biophys Res Commun 2010; 393:542-5. [PMID: 20153724 DOI: 10.1016/j.bbrc.2010.02.051] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2010] [Accepted: 02/09/2010] [Indexed: 01/05/2023]
Abstract
Daxx is a multifunctional protein, regulating a wide range of important functions including apoptosis and transcription. However, the way Daxx is regulated is poorly understood. In our previous studies, we have found that Daxx forms a complex with the E3 ubiquitin ligase Mdm2 and the de-ubiquitinase Hausp. In the present work, we show that Daxx is ubiquitinated by Mdm2 in both in vitro and in vivo systems and Mdm2 reduces Daxx expression upon over-expression. We further demonstrate that Hausp critically controls the cellular level of Daxx most likely by inducing Daxx de-ubiquitination. These results reveal Mdm2 and Hausp as important regulators for Daxx functions by controlling Daxx ubiquitination and stability.
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Affiliation(s)
- Jun Tang
- State Key Laboratory of Agrobiotechnology, College of Veterinary Medicine, China Agricultural University, 2 Yuanmingyuan W. Rd., Haidian District, Beijing 100193, China.
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