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Peña-Gómez SG, Cristóbal-Mondragón GR, Vega-Palomo CR, Mora-García M, Félix-Pérez T, Rebolloso-Gómez Y, Calera MR, Sánchez-Olea R. Nucleocytoplasmic shuttling of the GPN-loop GTPase Gpn3 is regulated by serum and cell density in MCF-12A mammary cells. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2024; 1871:119685. [PMID: 38342311 DOI: 10.1016/j.bbamcr.2024.119685] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Revised: 01/07/2024] [Accepted: 02/01/2024] [Indexed: 02/13/2024]
Abstract
The best-known function of the essential GPN-loop GTPase Gpn3 is to contribute to RNA polymerase II assembly, a prerequisite for its nuclear targeting. Although this process occurs in the cytoplasm, we have previously shown that Gpn3 enters the cell nucleus before being polyubiquitinated. Here, we show that inhibiting Crm1-mediated nuclear export with leptomycin B, or the proteasome with MG132, caused the nuclear accumulation of recombinant and endogenous Gpn3 in MCF-12A cells. When added simultaneously, leptomycin B and MG132 had an additive effect. Analysis of Gpn3 primary sequence revealed the presence of at least five nuclear export sequence (NES) motifs, with some having a higher exposure to the solvent in the GTP-bound than GDP-bound state in a Gpn3 structural model. Inactivation of any of these NESes led to some degree of Gpn3 nuclear accumulation, although mutating NES1 or NES3 had the more robust effect. MCF-12A cells expressing exclusively a NES-deficient version of Gpn3R-Flag proliferated slower than cells expressing Gpn3R-Flag wt, indicating that nuclear export is important for Gpn3 function. Next, we searched for physiological conditions regulating Gpn3 nucleocytoplasmic shuttling. Interestingly, whereas Gpn3R-Flag was both nuclear and cytoplasmic in low-density growing MCF-12A cells, it was exclusively cytoplasmic in high-density areas. Furthermore, Gpn3R-Flag was cytoplasmic, mostly perinuclear, in sparse but starved MCF-12A cells, and serum-stimulation caused a rapid, although transient, Gpn3R-Flag nuclear accumulation. We conclude that Gpn3 nucleocytoplasmic shuttling is regulated by cell density and growth factors, and propose that Gpn3 has an unknown nuclear function positively linked to cell growth and/or proliferation.
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Affiliation(s)
- Sonia G Peña-Gómez
- Instituto de Física, Universidad Autónoma de San Luis Potosí, SLP, México
| | | | | | - Martín Mora-García
- Instituto de Física, Universidad Autónoma de San Luis Potosí, SLP, México
| | - Tania Félix-Pérez
- Instituto de Física, Universidad Autónoma de San Luis Potosí, SLP, México
| | | | - Mónica R Calera
- Instituto de Física, Universidad Autónoma de San Luis Potosí, SLP, México.
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2
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Korf L, Ye X, Vogt MS, Steinchen W, Watad M, van der Does C, Tourte M, Sivabalasarma S, Albers SV, Essen LO. Archaeal GPN-loop GTPases involve a lock-switch-rock mechanism for GTP hydrolysis. mBio 2023; 14:e0085923. [PMID: 37962382 PMCID: PMC10746158 DOI: 10.1128/mbio.00859-23] [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: 04/05/2023] [Accepted: 10/05/2023] [Indexed: 11/15/2023] Open
Abstract
IMPORTANCE GPN-loop GTPases have been found to be crucial for eukaryotic RNA polymerase II assembly and nuclear trafficking. Despite their ubiquitous occurrence in eukaryotes and archaea, the mechanism by which these GTPases mediate their function is unknown. Our study on an archaeal representative from Sulfolobus acidocaldarius showed that these dimeric GTPases undergo large-scale conformational changes upon GTP hydrolysis, which can be summarized as a lock-switch-rock mechanism. The observed requirement of SaGPN for motility appears to be due to its large footprint on the archaeal proteome.
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Affiliation(s)
- Lukas Korf
- Department of Chemistry, Philipps University, Marburg, Germany
| | - Xing Ye
- University of Freiburg, Institute of Biology, Molecular Biology of Archaea, Freiburg, Germany
| | - Marian S. Vogt
- Department of Chemistry, Philipps University, Marburg, Germany
| | - Wieland Steinchen
- Department of Chemistry, Philipps University, Marburg, Germany
- Center for Synthetic Microbiology (SYNMIKRO), Karl-von-Frisch-Strasse, Marburg, Germany
| | - Mohamed Watad
- Department of Chemistry, Philipps University, Marburg, Germany
| | - Chris van der Does
- University of Freiburg, Institute of Biology, Molecular Biology of Archaea, Freiburg, Germany
| | - Maxime Tourte
- University of Freiburg, Institute of Biology, Molecular Biology of Archaea, Freiburg, Germany
| | - Shamphavi Sivabalasarma
- University of Freiburg, Institute of Biology, Molecular Biology of Archaea, Freiburg, Germany
- Spemann Graduate School of Biology and Medicine, University of Freiburg, Freiburg, Germany
| | - Sonja-Verena Albers
- University of Freiburg, Institute of Biology, Molecular Biology of Archaea, Freiburg, Germany
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3
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Targeting HNRNPM Inhibits Cancer Stemness and Enhances Antitumor Immunity in Wnt-activated Hepatocellular Carcinoma. Cell Mol Gastroenterol Hepatol 2022; 13:1413-1447. [PMID: 35158098 PMCID: PMC8938476 DOI: 10.1016/j.jcmgh.2022.02.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/25/2021] [Revised: 02/04/2022] [Accepted: 02/04/2022] [Indexed: 01/10/2023]
Abstract
BACKGROUND & AIMS Cancer stemness and immune evasion are closely associated and play critical roles in tumor development and resistance to immunotherapy. However, little is known about the underlying molecular mechanisms that coordinate this association. METHODS The expressions of heterogeneous nuclear ribonucleoprotein M (HNRNPM) in 240 hepatocellular carcinoma (HCC) samples, public databases, and liver development databases were analyzed. Chromatin immunoprecipitation assays were performed to explore the associations between stem-cell transcription factors and HNRNPM. HNRNPM-regulated alternative splicing (AS) and its binding motif were identified by RNA-seq and RIP-seq. HNRNPM-specific antisense oligonucleotides were developed to explore potential therapeutic targets in HCC. CD8+ T cells that were co-cultured with tumor cells were sorted by flow cytometry assays. RESULTS We identified an elevated oncofetal splicing factor in HCC, HNRNPM, that unifies and regulates the positive association between cancer stemness and immune evasion. HNRNPM knockdown abolished HCC tumorigenesis and diminished cancer stem cell properties in vitro and in vivo. Mechanistically, HNRNPM regulated the AS of MBD2 by binding its flanking introns, whose isoforms played opposing roles. Although MBD2a and MBD2c competitively bound to CpG islands in the FZD3 promoter, MBD2a preferentially increased FZD3 expression and then activated the WNT/β-catenin pathway. Interestingly, FZD3 and β-catenin further provided additional regulation by targeting OCT4 and SOX2. We found that HNRNPM inhibition significantly promoted CD8+ T cell activation and that HNRNPM- antisense oligonucleotides effectively inhibited WNT/β-catenin to enhance anti-programmed cell death protein-1 immunotherapy by promoting CD8+ T cell infiltration. CONCLUSIONS HNRNPM has a tumor-intrinsic function in generating an immunosuppressive HCC environment through an AS-dependent mechanism and demonstrates proof of the concept of targeting HNRNPM in tailoring HCC immunotherapeutic approaches.
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Minaker SW, Kofoed MC, Hieter P, Stirling PC. A nuclear proteome localization screen reveals the exquisite specificity of Gpn2 in RNA polymerase biogenesis. Cell Cycle 2021; 20:1361-1373. [PMID: 34180355 DOI: 10.1080/15384101.2021.1943879] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
The GPN proteins are a conserved family of GTP-binding proteins that are involved in the assembly and subsequent import of RNA polymerase II and III. In this study, we sought to ascertain the specificity of yeast GPN2 for RNA polymerases by screening the localization of a collection of 1350 GFP-tagged nuclear proteins in WT or GPN2 mutant cells. We found that the strongest mislocalization occurred for RNA polymerase II and III subunits and only a handful of other RNAPII associated proteins were altered in GPN2 mutant cells. Our screen identified Ess1, an Rpb1 C-terminal domain (CTD) prolyl isomerase, as mislocalized in GPN2 mutants. Building on this observation we tested for effects of mutations in other factors which regulate Rpb1-CTD phosphorylation status. This uncovered significant changes in nuclear-cytoplasmic distribution of Rpb1-GFP in strains with disrupted RNA polymerase CTD kinases or phosphatases. Overall, this screen shows the exquisite specificity of GPN2 for RNA polymerase transport, and reveals a previously unappreciated role for CTD modification in RNAPII nuclear localization.
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Affiliation(s)
- Sean W Minaker
- Terry Fox Laboratories, BC Cancer Research Institute, Vancouver, Canada
| | - Megan C Kofoed
- Michael Smith Laboratory, University of British Columbia, Vancouver, Canada
| | - Philip Hieter
- Michael Smith Laboratory, University of British Columbia, Vancouver, Canada.,Department of Medical Genetics, University of British Columbia, Vancouver, Canada
| | - Peter C Stirling
- Terry Fox Laboratories, BC Cancer Research Institute, Vancouver, Canada
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5
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Liu Z, Sun L, Cai Y, Shen S, Zhang T, Wang N, Wu G, Ma W, Li ST, Suo C, Hao Y, Jia WD, Semenza GL, Gao P, Zhang H. Hypoxia-Induced Suppression of Alternative Splicing of MBD2 Promotes Breast Cancer Metastasis via Activation of FZD1. Cancer Res 2021; 81:1265-1278. [PMID: 33402389 DOI: 10.1158/0008-5472.can-20-2876] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Revised: 11/19/2020] [Accepted: 12/29/2020] [Indexed: 11/16/2022]
Abstract
Metastasis is responsible for the majority of breast cancer-related deaths, however, the mechanisms underlying metastasis in this disease remain largely elusive. Here we report that under hypoxic conditions, alternative splicing of MBD2 is suppressed, favoring the production of MBD2a, which facilitates breast cancer metastasis. Specifically, MBD2a promoted, whereas its lesser known short form MBD2c suppressed metastasis. Activation of HIF1 under hypoxia facilitated MBD2a production via repression of SRSF2-mediated alternative splicing. As a result, elevated MBD2a outcompeted MBD2c for binding to promoter CpG islands to activate expression of FZD1, thereby promoting epithelial-to-mesenchymal transition and metastasis. Strikingly, clinical data reveal significantly correlated expression of MBD2a and MBD2c with the invasiveness of malignancy, indicating opposing roles for MBD2 splicing variants in regulating human breast cancer metastasis. Collectively, our findings establish a novel link between MBD2 switching and tumor metastasis and provide a promising therapeutic strategy and predictive biomarkers for hypoxia-driven breast cancer metastasis. SIGNIFICANCE: This study defines the opposing roles and clinical relevance of MBD2a and MBD2c, two MBD2 alternative splicing products, in hypoxia-driven breast cancer metastasis. GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/81/5/1265/F1.large.jpg.
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Affiliation(s)
- Zhaoji Liu
- Department of General Surgery, Anhui Provincial Hospital, The First Affiliated Hospital of USTC, University of Science and Technology of China, Hefei, China
- Hefei National Laboratory for Physical Sciences at Microscale, The CAS Key Laboratory of Innate Immunity and Chronic Disease, School of Life Sciences and Medical Center, University of Science and Technology of China, Hefei, China
| | - Linchong Sun
- Department of General Surgery, Anhui Provincial Hospital, The First Affiliated Hospital of USTC, University of Science and Technology of China, Hefei, China
- Laboratory of Cancer and Stem Cell Metabolism, School of Medicine, Institutes for Life Sciences, South China University of Technology, Guangzhou, China
| | - Yongping Cai
- Department of Pathology, School of Medicine, Anhui Medical University, Hefei, China
| | - Shengqi Shen
- Department of General Surgery, Anhui Provincial Hospital, The First Affiliated Hospital of USTC, University of Science and Technology of China, Hefei, China
- Hefei National Laboratory for Physical Sciences at Microscale, The CAS Key Laboratory of Innate Immunity and Chronic Disease, School of Life Sciences and Medical Center, University of Science and Technology of China, Hefei, China
| | - Tong Zhang
- Department of General Surgery, Anhui Provincial Hospital, The First Affiliated Hospital of USTC, University of Science and Technology of China, Hefei, China
- Hefei National Laboratory for Physical Sciences at Microscale, The CAS Key Laboratory of Innate Immunity and Chronic Disease, School of Life Sciences and Medical Center, University of Science and Technology of China, Hefei, China
| | - Nana Wang
- Department of Pathology, School of Medicine, Anhui Medical University, Hefei, China
| | - Gongwei Wu
- Department of General Surgery, Anhui Provincial Hospital, The First Affiliated Hospital of USTC, University of Science and Technology of China, Hefei, China
| | - Wenhao Ma
- Department of General Surgery, Anhui Provincial Hospital, The First Affiliated Hospital of USTC, University of Science and Technology of China, Hefei, China
| | - Shi-Ting Li
- Department of General Surgery, Anhui Provincial Hospital, The First Affiliated Hospital of USTC, University of Science and Technology of China, Hefei, China
| | - Caixia Suo
- Laboratory of Cancer and Stem Cell Metabolism, School of Medicine, Institutes for Life Sciences, South China University of Technology, Guangzhou, China
| | - Yijie Hao
- Department of General Surgery, Anhui Provincial Hospital, The First Affiliated Hospital of USTC, University of Science and Technology of China, Hefei, China
| | - Wei-Dong Jia
- Department of General Surgery, Anhui Provincial Hospital, The First Affiliated Hospital of USTC, University of Science and Technology of China, Hefei, China
| | - Gregg L Semenza
- School of Medicine, Johns Hopkins University, Baltimore, Maryland
| | - Ping Gao
- Hefei National Laboratory for Physical Sciences at Microscale, The CAS Key Laboratory of Innate Immunity and Chronic Disease, School of Life Sciences and Medical Center, University of Science and Technology of China, Hefei, China.
- Laboratory of Cancer and Stem Cell Metabolism, School of Medicine, Institutes for Life Sciences, South China University of Technology, Guangzhou, China
- Guangzhou Regenerative Medicine and Health Guangdong Laboratory, Guangzhou, China
| | - Huafeng Zhang
- Department of General Surgery, Anhui Provincial Hospital, The First Affiliated Hospital of USTC, University of Science and Technology of China, Hefei, China.
- Hefei National Laboratory for Physical Sciences at Microscale, The CAS Key Laboratory of Innate Immunity and Chronic Disease, School of Life Sciences and Medical Center, University of Science and Technology of China, Hefei, China
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6
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Barbosa-Camacho AA, Méndez-Hernández LE, Lara-Chacón B, Peña-Gómez SG, Romero V, González-González R, Guerra-Moreno JA, Robledo-Rivera AY, Sánchez-Olea R, Calera MR. The Gpn3 Q279* cancer-associated mutant inhibits Gpn1 nuclear export and is deficient in RNA polymerase II nuclear targeting. FEBS Lett 2017; 591:3555-3566. [PMID: 28940195 DOI: 10.1002/1873-3468.12856] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2017] [Revised: 09/11/2017] [Accepted: 09/15/2017] [Indexed: 11/07/2022]
Abstract
Gpn3 is required for RNA polymerase II (RNAPII) nuclear targeting. Here, we investigated the effect of a cancer-associated Q279* nonsense mutation in Gpn3 cellular function. Employing RNAi, we replaced endogenous Gpn3 by wt or Q279* RNAi-resistant Gpn3R in epithelial model cells. RNAPII nuclear accumulation and transcriptional activity were markedly decreased in cells expressing only Gpn3R Q279*. Wild-type Gpn3R localized to the cytoplasm but a fraction of Gpn3R Q279* entered the cell nucleus and inhibited Gpn1-EYFP nuclear export. This property and the transcriptional deficit in Gpn3R Q279*-expressing cells required a PDZ-binding motif generated by the Q279* mutation. We conclude that an acquired PDZ-binding motif in Gpn3 Q279* caused Gpn3 nuclear entry, and inhibited Gpn1 nuclear export and Gpn3-mediated RNAPII nuclear targeting.
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Affiliation(s)
| | | | | | | | - Violeta Romero
- Instituto de Física, Universidad Autónoma de San Luis Potosí, Mexico
| | | | | | | | | | - Mónica R Calera
- Instituto de Física, Universidad Autónoma de San Luis Potosí, Mexico
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7
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Sugitani N, Voehler MW, Roh MS, Topolska-Woś AM, Chazin WJ. Analysis of DNA binding by human factor xeroderma pigmentosum complementation group A (XPA) provides insight into its interactions with nucleotide excision repair substrates. J Biol Chem 2017; 292:16847-16857. [PMID: 28860187 DOI: 10.1074/jbc.m117.800078] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2017] [Revised: 08/31/2017] [Indexed: 11/06/2022] Open
Abstract
Xeroderma pigmentosum (XP) complementation group A (XPA) is an essential scaffolding protein in the multiprotein nucleotide excision repair (NER) machinery. The interaction of XPA with DNA is a core function of this protein; a number of mutations in the DNA-binding domain (DBD) are associated with XP disease. Although structures of the central globular domain of human XPA and data on binding of DNA substrates have been reported, the structural basis for XPA's DNA-binding activity remains unknown. X-ray crystal structures of the central globular domain of yeast XPA (Rad14) with lesion-containing DNA duplexes have provided valuable insights, but the DNA substrates used for this study do not correspond to the substrates of XPA as it functions within the NER machinery. To better understand the DNA-binding activity of human XPA in NER, we used NMR to investigate the interaction of its DBD with a range of DNA substrates. We found that XPA binds different single-stranded/double-stranded junction DNA substrates with a common surface. Comparisons of our NMR-based mapping of binding residues with the previously reported Rad14-DNA crystal structures revealed similarities and differences in substrate binding between XPA and Rad14. This includes direct evidence for DNA contacts to the residues extending C-terminally from the globular core, which are lacking in the Rad14 construct. Moreover, mutation of the XPA residue corresponding to Phe-262 in Rad14, previously reported as being critical for DNA binding, had only a moderate effect on the DNA-binding activity of XPA. The DNA-binding properties of several disease-associated mutations in the DBD were investigated. These results suggest that for XPA mutants exhibiting altered DNA-binding properties, a correlation exists between the extent of reduction in DNA-binding affinity and the severity of symptoms in XP patients.
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Affiliation(s)
- Norie Sugitani
- From the Departments of Chemistry and.,the Center for Structural Biology, Vanderbilt University, Nashville, Tennessee 37232-7917
| | - Markus W Voehler
- From the Departments of Chemistry and.,the Center for Structural Biology, Vanderbilt University, Nashville, Tennessee 37232-7917
| | | | - Agnieszka M Topolska-Woś
- the Center for Structural Biology, Vanderbilt University, Nashville, Tennessee 37232-7917.,Biochemistry and
| | - Walter J Chazin
- From the Departments of Chemistry and .,the Center for Structural Biology, Vanderbilt University, Nashville, Tennessee 37232-7917.,Biochemistry and
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8
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Human Gpn1 purified from bacteria binds guanine nucleotides and hydrolyzes GTP as a protein dimer stabilized by its C-terminal tail. Protein Expr Purif 2017; 132:85-96. [PMID: 28153773 DOI: 10.1016/j.pep.2017.01.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2016] [Revised: 12/23/2016] [Accepted: 01/25/2017] [Indexed: 12/20/2022]
Abstract
The essential GTPase Gpn1 mediates RNA polymerase II nuclear targeting and controls microtubule dynamics in yeast and human cells by molecular mechanisms still under investigation. Here, we purified human HisGpn1 expressed as a recombinant protein in bacteria E. coli BL-21 (DE3). Affinity purified HisGpn1 eluted from a size exclusion column as a protein dimer, a state conserved after removing the hexa-histidine tail and confirmed by separating HisGpn1 in native gels, and in dynamic light scattering experiments. Human HisGpn1 purity was higher than 95%, molecularly monodisperse and could be concentrated to more than 10 mg/mL without aggregating. Circular dichroism spectra showed that human HisGpn1 was properly folded and displayed a secondary structure rich in alpha helices. HisGpn1 effectively bound GDP and the non-hydrolyzable GTP analogue GMPPCP, and hydrolyzed GTP. We next tested the importance of the C-terminal tail, present in eukaryotic Gpn1 but not in the ancestral archaeal Gpn protein, on HisGpn1 dimer formation. C-terminal deleted human HisGpn1 (HisGpn1ΔC) was also purified as a protein dimer, indicating that the N-terminal GTPase domain contains the interaction surface needed for dimer formation. In contrast to HisGpn1, however, HisGpn1ΔC dimer spontaneously dissociated into monomers. In conclusion, we have developed a method to purify properly folded and functionally active human HisGpn1 from bacteria, and showed that the C-terminal tail, universally conserved in all eukaryotic Gpn1 orthologues, stabilizes the GTPase domain-mediated Gpn1 protein dimer. The availability of recombinant human Gpn1 will open new research avenues to unveil the molecular and pharmacological properties of this essential GTPase.
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9
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Sugitani N, Sivley RM, Perry KE, Capra JA, Chazin WJ. XPA: A key scaffold for human nucleotide excision repair. DNA Repair (Amst) 2016; 44:123-135. [PMID: 27247238 DOI: 10.1016/j.dnarep.2016.05.018] [Citation(s) in RCA: 82] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Nucleotide excision repair (NER) is essential for removing many types of DNA lesions from the genome, yet the mechanisms of NER in humans remain poorly understood. This review summarizes our current understanding of the structure, biochemistry, interaction partners, mechanisms, and disease-associated mutations of one of the critical NER proteins, XPA.
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Affiliation(s)
- Norie Sugitani
- Departments of Biochemistry, Biological Sciences, Biomedical Informatics, Chemistry, and Computer Science, and Vanderbilt Genetics Institute and Center for Structural Biology, Vanderbilt University, Nashville, TN 37232-7917, United States
| | - Robert M Sivley
- Departments of Biochemistry, Biological Sciences, Biomedical Informatics, Chemistry, and Computer Science, and Vanderbilt Genetics Institute and Center for Structural Biology, Vanderbilt University, Nashville, TN 37232-7917, United States
| | - Kelly E Perry
- Departments of Biochemistry, Biological Sciences, Biomedical Informatics, Chemistry, and Computer Science, and Vanderbilt Genetics Institute and Center for Structural Biology, Vanderbilt University, Nashville, TN 37232-7917, United States
| | - John A Capra
- Departments of Biochemistry, Biological Sciences, Biomedical Informatics, Chemistry, and Computer Science, and Vanderbilt Genetics Institute and Center for Structural Biology, Vanderbilt University, Nashville, TN 37232-7917, United States
| | - Walter J Chazin
- Departments of Biochemistry, Biological Sciences, Biomedical Informatics, Chemistry, and Computer Science, and Vanderbilt Genetics Institute and Center for Structural Biology, Vanderbilt University, Nashville, TN 37232-7917, United States.
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10
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Structure of GPN-Loop GTPase Npa3 and Implications for RNA Polymerase II Assembly. Mol Cell Biol 2015; 36:820-31. [PMID: 26711263 DOI: 10.1128/mcb.01009-15] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Accepted: 12/21/2015] [Indexed: 11/20/2022] Open
Abstract
Biogenesis of the 12-subunit RNA polymerase II (Pol II) transcription complex requires so-called GPN-loop GTPases, but the function of these enzymes is unknown. Here we report the first crystal structure of a eukaryotic GPN-loop GTPase, the Saccharomyces cerevisiae enzyme Npa3 (a homolog of human GPN1, also called RPAP4, XAB1, and MBDin), and analyze its catalytic mechanism. The enzyme was trapped in a GDP-bound closed conformation and in a novel GTP analog-bound open conformation displaying a conserved hydrophobic pocket distant from the active site. We show that Npa3 has chaperone activity and interacts with hydrophobic peptide regions of Pol II subunits that form interfaces in the assembled Pol II complex. Biochemical results are consistent with a model that the hydrophobic pocket binds peptides and that this can allosterically stimulate GTPase activity and subsequent peptide release. These results suggest that GPN-loop GTPases are assembly chaperones for Pol II and other protein complexes.
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11
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Alteration of Scn3a expression is mediated via CpG methylation and MBD2 in mouse hippocampus during postnatal development and seizure condition. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2014; 1849:1-9. [PMID: 25459751 DOI: 10.1016/j.bbagrm.2014.11.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2014] [Revised: 10/13/2014] [Accepted: 11/12/2014] [Indexed: 12/21/2022]
Abstract
Increased expression of sodium channel SCN3A, an embryonic-expressed gene, has been identified in epileptic tissues, which is believed to contribute to the development of epilepsy. However, the regulatory mechanism of SCN3A expression under epileptic condition is still unknown. Here we showed a high level of Scn3a mRNA expression in mouse embryonic hippocampus with gradually decreasing to a low level during the postnatal development and a methylation of a specific CpG site (-39C) in the Scn3a promoter was increased in hippocampus during postnatal development, corresponding to the downregulation of Scn3a expression. Furthermore, in vitro methylation and -39C>T mutation of the Scn3a promoter decreased the reporter gene expression, suggesting an important role of the -39C site in regulating gene expression. We then demonstrated that the sequence containing -39C was a MBD2-binding motif and the CpG methylation of the promoter region increased the capability of MBD2's binding to the motif. Knockdown of MBD2 in mouse N1E-115 cells led to the -39C methylation and the downregulation of Scn3a transcription by decreasing the Scn3a promoter activity. In the hippocampus of seizure mice, the expressions of Scn3a and Mbd2 were upregulated after 10-day KA treatment. At the same time point, the -39C site was demethylated and the capability of MBD2's binding to the Scn3a promoter motif was decreased. Taken together, these findings suggest that CpG methylation and MBD2 are involved in altering Scn3a expression during postnatal development and seizure condition.
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12
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Gpn1 and Gpn3 associate tightly and their protein levels are mutually dependent in mammalian cells. FEBS Lett 2014; 588:3823-9. [DOI: 10.1016/j.febslet.2014.08.038] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2014] [Revised: 08/03/2014] [Accepted: 08/28/2014] [Indexed: 11/24/2022]
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13
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Forget D, Lacombe AA, Cloutier P, Lavallée-Adam M, Blanchette M, Coulombe B. Nuclear import of RNA polymerase II is coupled with nucleocytoplasmic shuttling of the RNA polymerase II-associated protein 2. Nucleic Acids Res 2013; 41:6881-91. [PMID: 23723243 PMCID: PMC3737550 DOI: 10.1093/nar/gkt455] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The RNA polymerase II (RNAP II)-associated protein (RPAP) 2 has been discovered through its association with various subunits of RNAP II in affinity purification coupled with mass spectrometry experiments. Here, we show that RPAP2 is a mainly cytoplasmic protein that shuttles between the cytoplasm and the nucleus. RPAP2 shuttling is tightly coupled with nuclear import of RNAP II, as RPAP2 silencing provokes abnormal accumulation of RNAP II in the cytoplasmic space. Most notably, RPAP4/GPN1 silencing provokes the retention of RPAP2 in the nucleus. Our results support a model in which RPAP2 enters the nucleus in association with RNAP II and returns to the cytoplasm in association with the GTPase GPN1/RPAP4. Although binding of RNAP II to RPAP2 is mediated by an N-terminal domain (amino acids 1–170) that contains a nuclear retention domain, and binding of RPAP4/GPN1 to RPAP2 occurs through a C-terminal domain (amino acids 156–612) that has a dominant cytoplasmic localization domain. In conjunction with previously published data, our results have important implications, as they indicate that RPAP2 controls gene expression by two distinct mechanisms, one that targets RNAP II activity during transcription and the other that controls availability of RNAP II in the nucleus.
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Affiliation(s)
- Diane Forget
- Institut de Recherches Cliniques de Montréal (IRCM), Montréal, Québec, Canada H2W 1R7, McGill Centre for Bioinformatics and School of Computer Science, McGill University, Montréal, Québec, Canada H3A 2B4
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14
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Alonso B, Beraud C, Meguellati S, Chen SW, Pellequer JL, Armengaud J, Godon C. Eukaryotic GPN-loop GTPases paralogs use a dimeric assembly reminiscent of archeal GPN. Cell Cycle 2013; 12:463-72. [PMID: 23324351 PMCID: PMC3587447 DOI: 10.4161/cc.23367] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
GTPases are molecular switches that regulate a wide-range of cellular processes. The GPN-loop GTPase (GPN) is a sub-family of P-loop NTPase that evolved from a single gene copy in archaea to triplicate paralog genes in eukaryotes, each having a non-redundant essential function in cell. In Saccharomyces cerevisiae, yGPN1 and yGPN2 are involved in sister chromatid cohesion mechanism, whereas nothing is known regarding yGPN3 function. Previous high-throughput experiments suggested that GPN paralogs interaction may occur. In this work, GPN|GPN contact was analyzed in details using TAP-Tag approach, yeast two-hybrid assay, in silico energy computation and site-directed mutagenesis of a conserved Glu residue located at the center of the interaction interface. It is demonstrated that this residue is essential for cell viability. A chromatid cohesion assay revealed that, like yGPN1 and yGPN2, yGPN3 also plays a role in sister chromatid cohesion. These results suggest that all three GPN proteins act at the molecular level in sister chromatid cohesion mechanism as a GPN|GPN complex reminiscent of the homodimeric structure of PAB0955, an archaeal member of GPN-loop GTPase.
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Affiliation(s)
- Béatrice Alonso
- CEA, iBEB, Service de Biochimie et Toxicologie Nucléaire/LBSP, Bagnols-sur-Cèze, France
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15
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Szemes M, Dallosso AR, Melegh Z, Curry T, Li Y, Rivers C, Uney J, Mägdefrau AS, Schwiderski K, Park JH, Brown KW, Shandilya J, Roberts SGE, Malik K. Control of epigenetic states by WT1 via regulation of de novo DNA methyltransferase 3A. Hum Mol Genet 2013; 22:74-83. [PMID: 23042785 PMCID: PMC6296327 DOI: 10.1093/hmg/dds403] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2012] [Accepted: 09/20/2012] [Indexed: 12/21/2022] Open
Abstract
Although tumour suppressor gene hypermethylation is a universal feature of cancer cells, little is known about the necessary molecular triggers. Here, we show that Wilms' tumour 1 (WT1), a developmental master regulator that can also act as a tumour suppressor or oncoprotein, transcriptionally regulates the de novo DNA methyltransferase 3A (DNMT3A) and that cellular WT1 levels can influence DNA methylation of gene promoters genome-wide. Specifically, we demonstrate that depletion of WT1 by short-interfering RNAs leads to reduced DNMT3A in Wilms' tumour cells and human embryonal kidney-derived cell lines. Chromatin immunoprecipitation assays demonstrate WT1 recruitment to the DNMT3A promoter region and reporter assays confirm that WT1 directly transactivates DNMT3A expression. Consistent with this regulatory role, immunohistochemical analysis shows co-expression of WT1 and DNMT3A proteins in nuclei of blastemal cells in human fetal kidney and Wilms' tumours. Using genome-wide promoter methylation arrays, we show that human embryonal kidney cells over-expressing WT1 acquire DNA methylation changes at specific gene promoters where DNMT3A recruitment is increased, with hypermethylation being associated with silencing of gene expression. Elevated DNMT3A is also demonstrated at hypermethylated genes in Wilms' tumour cells, including a region of long-range epigenetic silencing. Finally, we show that depletion of WT1 in Wilms' tumour cells can lead to reactivation of gene expression from methylated promoters, such as TGFB2, a key modulator of epithelial-mesenchymal transitions. Collectively, our work defines a new regulatory modality for WT1 involving elicitation of epigenetic alterations which is most likely crucial to its functions in development and disease.
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Affiliation(s)
| | | | - Zsombor Melegh
- Department of Cellular Pathology, Southmead Hospital, Bristol, UK
| | | | - Yifan Li
- Cancer Epigenetics Laboratory and
| | - Caroline Rivers
- Henry Wellcome Laboratories, Dorothy Hodgkin Building, University of Bristol, Bristol, UK and
| | - James Uney
- Henry Wellcome Laboratories, Dorothy Hodgkin Building, University of Bristol, Bristol, UK and
| | | | | | | | | | - Jayasha Shandilya
- Department of Biological Sciences, University at Buffalo (SUNY), 625 Cooke Hall, Buffalo, NY 14260, USA
| | - Stefan G. E. Roberts
- Gene Expression Laboratory, Cellular and Molecular Medicine, School of Medical Sciences, University of Bristol, Bristol BS8 1TD, UK
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16
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Reyes-Pardo H, Barbosa-Camacho AA, Pérez-Mejía AE, Lara-Chacón B, Salas-Estrada LA, Robledo-Rivera AY, Montero-Morán GM, Lara-González S, Calera MR, Sánchez-Olea R. A nuclear export sequence in GPN-loop GTPase 1, an essential protein for nuclear targeting of RNA polymerase II, is necessary and sufficient for nuclear export. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012; 1823:1756-66. [PMID: 22796641 DOI: 10.1016/j.bbamcr.2012.07.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2012] [Revised: 07/02/2012] [Accepted: 07/03/2012] [Indexed: 11/16/2022]
Abstract
XAB1/Gpn1 is a GTPase that associates with RNA polymerase II (RNAPII) in a GTP-dependent manner. Although XAB1/Gpn1 is essential for nuclear accumulation of RNAPII, the underlying mechanism is not known. A XAB1/Gpn1-EYFP fluorescent protein, like endogenous XAB1/Gpn1, localized to the cytoplasm but it rapidly accumulated in the cell nucleus in the presence of leptomycin B, a chemical inhibitor of the nuclear transport receptor Crm1. Crm1 recognizes short peptides in substrate proteins called nuclear export sequences (NES). Here, we employed site-directed mutagenesis and fluorescence microscopy to assess the functionality of all six putative NESs in XAB1/Gpn1. Mutating five of the six putative NESs did not alter the cytoplasmic localization of XAB1/Gpn1-EYFP. However, a V302A/L304A double mutant XAB1/Gpn1-EYFP protein was clearly accumulated in the cell nucleus, indicating the disruption of a functional NES. This functional XAB1/Gpn1 NES displays all features present in most common and potent NESs, including, in addition to Φ1-Φ4, a critical fifth hydrophobic amino acid Φ0. Therefore, in human Gpn1 this NES spans amino acids 292-LERLRKDMGSVAL-304. XAB1/Gpn1 NES is remarkably conserved during evolution. XAB1/Gpn1 NES was sufficient for nuclear export activity, as it caused a complete exclusion of EYFP from the cell nucleus. Molecular modeling of XAB1/Gpn1 provided a mechanistic reason for NES selection, as functionality correlated with accessibility, and it also suggested a mechanism for NES inhibition by intramolecular masking. In conclusion, we have identified a highly active, evolutionarily conserved NES in XAB1/Gpn1 that is critical for nucleo-cytoplasmic shuttling and steady-state cytoplasmic localization of XAB1/Gpn1.
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Affiliation(s)
- Humberto Reyes-Pardo
- Instituto de Física, Universidad Autónoma de San Luis Potosí, Zona Universitaria, San Luis Potosí, San Luis Potosí, México
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17
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Pero R, Palmieri D, Angrisano T, Valentino T, Federico A, Franco R, Lembo F, Klein-Szanto AJ, Del Vecchio L, Montanaro D, Keller S, Arra C, Papadopoulou V, Wagner SD, Croce CM, Fusco A, Chiariotti L, Fedele M. POZ-, AT-hook-, and zinc finger-containing protein (PATZ) interacts with human oncogene B cell lymphoma 6 (BCL6) and is required for its negative autoregulation. J Biol Chem 2012; 287:18308-17. [PMID: 22493480 DOI: 10.1074/jbc.m112.346270] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The PATZ1 gene encoding a POZ/AT-hook/Kruppel zinc finger (PATZ) transcription factor, is considered a cancer-related gene because of its loss or misexpression in human neoplasias. As for other POZ/domain and Kruppel zinc finger (POK) family members, the transcriptional activity of PATZ is due to the POZ-mediated oligomer formation, suggesting that it might be not a typical transactivator but an architectural transcription factor, thus functioning either as activator or as repressor depending on the presence of proteins able to interact with it. Therefore, to better elucidate PATZ function, we searched for its molecular partners. By yeast two-hybrid screenings, we found a specific interaction between PATZ and BCL6, a human oncogene that plays a key role in germinal center (GC) derived neoplasias. We demonstrate that PATZ and BCL6 interact in germinal center-derived B lymphoma cells, through the POZ domain of PATZ. Moreover, we show that PATZ is able to bind the BCL6 regulatory region, where BCL6 itself acts as a negative regulator, and to contribute to negatively modulate its activity. Consistently, disruption of one or both Patz1 alleles in mice causes focal expansion of thymus B cells, in which BCL6 is up-regulated. This phenotype was almost completely rescued by crossing Patz1(+/-) with Bcl6(+/-) mice, indicating a key role for Bcl6 expression in its development. Finally, a significant number of Patz1 knock-out mice (both heterozygous and homozygous) also develop BCL6-expressing lymphomas. Therefore, the disruption of one or both Patz1 alleles may favor lymphomagenesis by activating the BCL6 pathway.
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Affiliation(s)
- Raffaela Pero
- Dipartimento di Biologia e Patologia Cellulare e Molecolare, Università di Napoli Federico II and Consiglio Nazionale delle Ricerche (CNR), Naples, Italy
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18
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Staresincic L, Walker J, Dirac-Svejstrup AB, Mitter R, Svejstrup JQ. GTP-dependent binding and nuclear transport of RNA polymerase II by Npa3 protein. J Biol Chem 2011; 286:35553-35561. [PMID: 21844196 PMCID: PMC3195585 DOI: 10.1074/jbc.m111.286161] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2011] [Indexed: 11/06/2022] Open
Abstract
We identified XAB1 in a proteomic screen for factors that interact with human RNA polymerase II (RNAPII). Because XAB1 has a conserved Saccharomyces cerevisiae homologue called Npa3, yeast genetics and biochemical analysis were used to dissect the significance of the interaction. Degron-dependent Npa3 depletion resulted in genome-wide transcription decreases, correlating with a loss of RNAPII from genes as measured by chromatin immunoprecipitation. Surprisingly, however, transcription in vitro was unaffected by Npa3, suggesting that it affects a process that is not required for transcription in yeast extracts. Indeed, Npa3 depletion in vivo affects nuclear localization of RNAPII; the polymerase accumulates in the cytoplasm. Npa3 is a member of the GPN-LOOP family of GTPases. Npa3 mutants that either cannot bind GTP or that bind but cannot hydrolyze it are inviable and unable to support nuclear transport of RNAPII. Surprisingly, we were unable to detect interactions between Npa3 and proteins in the classical importin α/β pathway for nuclear import. Interestingly, Npa3-RNAPII binding is significantly increased by the addition of GTP or its slowly hydrolyzable analogue guanosine 5'-3-O-(thio)triphosphate (GTPγS). Moreover, the Npa3 mutant that binds GTP, but cannot hydrolyze it, binds RNAPII even in the absence of added GTP, whereas the mutant that cannot bind GTP is unable to bind the polymerase. Together, our data suggest that Npa3 defines an unconventional pathway for nuclear import of RNAPII, which involves GTP-dependent binding of Npa3 to the polymerase.
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Affiliation(s)
- Lidija Staresincic
- Mechanisms of Transcription Laboratory, Clare Hall Laboratories, Cancer Research UK London Research Institute, South Mimms EN6 3LD
| | - Jane Walker
- Mechanisms of Transcription Laboratory, Clare Hall Laboratories, Cancer Research UK London Research Institute, South Mimms EN6 3LD
| | - A Barbara Dirac-Svejstrup
- Mechanisms of Transcription Laboratory, Clare Hall Laboratories, Cancer Research UK London Research Institute, South Mimms EN6 3LD
| | - Richard Mitter
- Bioinformatics and Biostatistics Group, Cancer Research UK London Research Institute, 44 Lincoln's Inn Fields, London WC2A 3LY, United Kingdom
| | - Jesper Q Svejstrup
- Mechanisms of Transcription Laboratory, Clare Hall Laboratories, Cancer Research UK London Research Institute, South Mimms EN6 3LD.
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19
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Human GTPases associate with RNA polymerase II to mediate its nuclear import. Mol Cell Biol 2011; 31:3953-62. [PMID: 21768307 DOI: 10.1128/mcb.05442-11] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Small GTPases share a biochemical mechanism and act as binary molecular switches. One important function of small GTPases in the cell is nucleocytoplasmic transport of both proteins and RNA. Here, we show the stable association of human GPN1 and GPN3, small GTPases related to Ran, with RNA polymerase II (RNAPII) isolated from either the cytoplasmic or nuclear fraction. GPN1 and GPN3 directly interact with RNAPII subunit 7 (RPB7)/RPB4 and the C-terminal domain (CTD) of RNAPII. Depletion of GPN1 or GPN3 using small interfering RNAs led to decreased RNAPII levels in the nucleus and an accumulation of this enzyme in the cytoplasm of human cells. Furthermore, isolation of a GPN1/GPN3/RNAPII complex from stable cell lines expressing a dominant negative GPN1 harboring mutations in the GTP-binding pocket demonstrated a role for these proteins in nuclear import of RNAPII. Thus, GPN1/GPN3 define a new family of small GTPases that are specialized for the transport of RNA polymerase II into the nucleus.
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20
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Angrisano T, Sacchetti S, Natale F, Cerrato A, Pero R, Keller S, Peluso S, Perillo B, Avvedimento VE, Fusco A, Bruni CB, Lembo F, Santoro M, Chiariotti L. Chromatin and DNA methylation dynamics during retinoic acid-induced RET gene transcriptional activation in neuroblastoma cells. Nucleic Acids Res 2010; 39:1993-2006. [PMID: 20952403 PMCID: PMC3064803 DOI: 10.1093/nar/gkq864] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Although it is well known that RET gene is strongly activated by retinoic acid (RA) in neuroblastoma cells, the mechanisms underlying such activation are still poorly understood. Here we show that a complex series of molecular events, that include modifications of both chromatin and DNA methylation state, accompany RA-mediated RET activation. Our results indicate that the primary epigenetic determinants of RA-induced RET activation differ between enhancer and promoter regions. At promoter region, the main mark of RET activation was the increase of H3K4me3 levels while no significant changes of the methylation state of H3K27 and H3K9 were observed. At RET enhancer region a bipartite chromatin domain was detected in unstimulated cells and a prompt demethylation of H3K27me3 marked RET gene activation upon RA exposure. Moreover, ChIP experiments demonstrated that EZH2 and MeCP2 repressor complexes were associated to the heavily methylated enhancer region in the absence of RA while both complexes were displaced during RA stimulation. Finally, our data show that a demethylation of a specific CpG site at the enhancer region could favor the displacement of MeCP2 from the heavily methylated RET enhancer region providing a novel potential mechanism for transcriptional regulation of methylated RA-regulated loci.
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Affiliation(s)
- T Angrisano
- Dipartimento di Biologia e Patologia Cellulare e Molecolare and Istituto di Endocrinologia ed Oncologia Sperimentale CNR, Università degli Studi di Napoli 'Federico II' 80131 Naples, Italy
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21
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Forget D, Lacombe AA, Cloutier P, Al-Khoury R, Bouchard A, Lavallée-Adam M, Faubert D, Jeronimo C, Blanchette M, Coulombe B. The protein interaction network of the human transcription machinery reveals a role for the conserved GTPase RPAP4/GPN1 and microtubule assembly in nuclear import and biogenesis of RNA polymerase II. Mol Cell Proteomics 2010; 9:2827-39. [PMID: 20855544 PMCID: PMC3002788 DOI: 10.1074/mcp.m110.003616] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
RNA polymerase II (RNAPII), the 12-subunit enzyme that synthesizes all mRNAs and several non-coding RNAs in eukaryotes, plays a central role in cell function. Although multiple proteins are known to regulate the activity of RNAPII during transcription, little is known about the machinery that controls the fate of the enzyme before or after transcription. We used systematic protein affinity purification coupled to mass spectrometry (AP-MS) to characterize the high resolution network of protein interactions of RNAPII in the soluble fraction of human cell extracts. Our analysis revealed that many components of this network participate in RNAPII biogenesis. We show here that RNAPII-associated protein 4 (RPAP4/GPN1) shuttles between the nucleus and the cytoplasm and regulates nuclear import of POLR2A/RPB1 and POLR2B/RPB2, the two largest subunits of RNAPII. RPAP4/GPN1 is a member of a newly discovered GTPase family that contains a unique and highly conserved GPN loop motif that we show is essential, in conjunction with its GTP-binding motifs, for nuclear localization of POLR2A/RPB1 in a process that also requires microtubule assembly. A model for RNAPII biogenesis is presented.
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Affiliation(s)
- Diane Forget
- Institut de recherches cliniques de Montréal, Montréal, Québec H2W1R7, Canada
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22
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Shell SM, Zou Y. Other proteins interacting with XP proteins. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2009; 637:103-12. [PMID: 19181115 DOI: 10.1007/978-0-387-09599-8_11] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Steven M Shell
- Department of Biochemistry and Molecular Biology, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, Tennessee 37614, USA
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23
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Szyf M. DNA demethylation and cancer metastasis: therapeutic implications. Expert Opin Drug Discov 2008; 3:519-31. [DOI: 10.1517/17460441.3.5.519] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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24
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Berthon J, Cortez D, Forterre P. Genomic context analysis in Archaea suggests previously unrecognized links between DNA replication and translation. Genome Biol 2008; 9:R71. [PMID: 18400081 PMCID: PMC2643942 DOI: 10.1186/gb-2008-9-4-r71] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2007] [Revised: 02/22/2008] [Accepted: 04/09/2008] [Indexed: 11/05/2022] Open
Abstract
Specific functional interactions of proteins involved in DNA replication and/or DNA repair or transcription might occur in Archaea, suggesting a previously unrecognized regulatory network coupling DNA replication and translation, which might also exist in Eukarya. Background Comparative analysis of genomes is valuable to explore evolution of genomes, deduce gene functions, or predict functional linking between proteins. Here, we have systematically analyzed the genomic environment of all known DNA replication genes in 27 archaeal genomes to infer new connections for DNA replication proteins from conserved genomic associations. Results Two distinct sets of DNA replication genes frequently co-localize in archaeal genomes: the first includes the genes for PCNA, the small subunit of the DNA primase (PriS), and Gins15; the second comprises the genes for MCM and Gins23. Other genomic associations of genes encoding proteins involved in informational processes that may be functionally relevant at the cellular level have also been noted; in particular, the association between the genes for PCNA, transcription factor S, and NudF. Surprisingly, a conserved cluster of genes coding for proteins involved in translation or ribosome biogenesis (S27E, L44E, aIF-2 alpha, Nop10) is almost systematically contiguous to the group of genes coding for PCNA, PriS, and Gins15. The functional relevance of this cluster encoding proteins conserved in Archaea and Eukarya is strongly supported by statistical analysis. Interestingly, the gene encoding the S27E protein, also known as metallopanstimulin 1 (MPS-1) in human, is overexpressed in multiple cancer cell lines. Conclusion Our genome context analysis suggests specific functional interactions for proteins involved in DNA replication between each other or with proteins involved in DNA repair or transcription. Furthermore, it suggests a previously unrecognized regulatory network coupling DNA replication and translation in Archaea that may also exist in Eukarya.
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Affiliation(s)
- Jonathan Berthon
- Univ. Paris-Sud 11, CNRS, UMR8621, Institut de Génétique et Microbiologie, 91405 Orsay CEDEX, France.
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25
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Tshuikina M, Nilsson K, Öberg F. Positive histone marks are associated with active transcription from a methylated ICSBP/IRF8 gene. Gene 2008; 410:259-67. [DOI: 10.1016/j.gene.2007.12.013] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2007] [Revised: 12/04/2007] [Accepted: 12/13/2007] [Indexed: 12/20/2022]
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26
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Patra SK, Patra A, Rizzi F, Ghosh TC, Bettuzzi S. Demethylation of (Cytosine-5-C-methyl) DNA and regulation of transcription in the epigenetic pathways of cancer development. Cancer Metastasis Rev 2008; 27:315-34. [DOI: 10.1007/s10555-008-9118-y] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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27
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Wischnewski F, Friese O, Pantel K, Schwarzenbach H. Methyl-CpG binding domain proteins and their involvement in the regulation of the MAGE-A1, MAGE-A2, MAGE-A3, and MAGE-A12 gene promoters. Mol Cancer Res 2007; 5:749-59. [PMID: 17634428 DOI: 10.1158/1541-7786.mcr-06-0364] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Promoter hypermethylation is responsible for the restricted expression of the tumor-associated MAGE antigens. In order to elucidate the mechanism underlying methylation-dependent repression, we examined the involvement of methyl-CpG binding proteins, MBD1, MBD2a, and MeCP2, in silencing of MAGE-A1, MAGE-A2, MAGE-A3, and MAGE-A12 genes. Electrophoretic mobility shift assays displayed binding of MBD1 to the methylated and unmethylated MAGE-A promoters. Using chromatin immunoprecipitation assays, in vivo binding of MBD1 and MeCP2 to the promoters could be observed in MCF-7 and T47D cells. Transient transfection assays of MCF-7 cells were done with the transcriptional repression domains (TRD) of MBD1, MBD2a, and MeCP2, and MAGE-A1, MAGE-A2, MAGE-A3, and MAGE-A12 promoters. Whereas the TRD of MBD1 and MeCP2 repressed the MAGE-A promoters, the TRD of MBD2 had no inhibiting effect on the promoter activity. Furthermore, cotransfections of Mbd1-deficient mouse fibroblasts and MCF-7 cells with MBD2a, MeCP2, and the MBD1 splice variants, 1v1 and 1v3, showed that strong methylation-dependent repression of the MAGE-A promoters could not be further down-regulated by these proteins. However, the two MBD1 splice variants, 1v1 and 1v3, were able to repress the basal activity of unmethylated MAGE-A promoters. Additional cotransfection experiments with both isoforms of MBD1 and the transcription factor Ets-1 showed that Ets-1 could not abrogate the MBD1-mediated suppression. In contrast with the repressive effect mediated by MBD1, MBD2a was found to up-regulate the basal activity of the promoters. In conclusion, these data show, for the first time, the involvement of methyl-CpG binding domain proteins in the regulation of the MAGE-A genes.
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Affiliation(s)
- Frank Wischnewski
- Institute of Tumor Biology, University Medical Center Hamburg-Eppendorf, Martinstrasse 52, 20246 Hamburg, Germany
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28
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Jeronimo C, Forget D, Bouchard A, Li Q, Chua G, Poitras C, Thérien C, Bergeron D, Bourassa S, Greenblatt J, Chabot B, Poirier GG, Hughes TR, Blanchette M, Price DH, Coulombe B. Systematic analysis of the protein interaction network for the human transcription machinery reveals the identity of the 7SK capping enzyme. Mol Cell 2007; 27:262-274. [PMID: 17643375 PMCID: PMC4498903 DOI: 10.1016/j.molcel.2007.06.027] [Citation(s) in RCA: 341] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2006] [Revised: 05/16/2007] [Accepted: 06/22/2007] [Indexed: 01/20/2023]
Abstract
We have performed a survey of soluble human protein complexes containing components of the transcription and RNA processing machineries using protein affinity purification coupled to mass spectrometry. Thirty-two tagged polypeptides yielded a network of 805 high-confidence interactions. Remarkably, the network is significantly enriched in proteins that regulate the formation of protein complexes, including a number of previously uncharacterized proteins for which we have inferred functions. The RNA polymerase II (RNAP II)-associated proteins (RPAPs) are physically and functionally associated with RNAP II, forming an interface between the enzyme and chaperone/scaffolding proteins. BCDIN3 is the 7SK snRNA methylphosphate capping enzyme (MePCE) present in an snRNP complex containing both RNA processing and transcription factors, including the elongation factor P-TEFb. Our results define a high-density protein interaction network for the mammalian transcription machinery and uncover multiple regulatory factors that target the transcription machinery.
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Affiliation(s)
- Célia Jeronimo
- Laboratory of Gene Transcription and Proteomics Discovery Platform, Institut de recherches cliniques de Montréal, 110 avenue des Pins Ouest, Montréal, QC H2W 1R7, Canada
| | - Diane Forget
- Laboratory of Gene Transcription and Proteomics Discovery Platform, Institut de recherches cliniques de Montréal, 110 avenue des Pins Ouest, Montréal, QC H2W 1R7, Canada
| | - Annie Bouchard
- Laboratory of Gene Transcription and Proteomics Discovery Platform, Institut de recherches cliniques de Montréal, 110 avenue des Pins Ouest, Montréal, QC H2W 1R7, Canada
| | - Qintong Li
- Biochemistry Department, University of Iowa, Iowa City, IA 52242-1109, USA
| | - Gordon Chua
- Banting and Best Department of Medical Research, University of Toronto, Toronto, ON M5G 1L6, Canada
| | - Christian Poitras
- Laboratory of Gene Transcription and Proteomics Discovery Platform, Institut de recherches cliniques de Montréal, 110 avenue des Pins Ouest, Montréal, QC H2W 1R7, Canada
| | - Cynthia Thérien
- Laboratory of Gene Transcription and Proteomics Discovery Platform, Institut de recherches cliniques de Montréal, 110 avenue des Pins Ouest, Montréal, QC H2W 1R7, Canada
| | - Dominique Bergeron
- Laboratory of Gene Transcription and Proteomics Discovery Platform, Institut de recherches cliniques de Montréal, 110 avenue des Pins Ouest, Montréal, QC H2W 1R7, Canada
| | - Sylvie Bourassa
- Centre hospitalier universitaire de Québec, Université Laval, Québec, QC G1V 4G2, Canada
| | - Jack Greenblatt
- Banting and Best Department of Medical Research, University of Toronto, Toronto, ON M5G 1L6, Canada
| | - Benoit Chabot
- Département de microbiologie et infectiologie, Université de Sherbrooke, Sherbrooke, QC J1H 5N4, Canada
| | - Guy G Poirier
- Centre hospitalier universitaire de Québec, Université Laval, Québec, QC G1V 4G2, Canada
| | - Timothy R Hughes
- Banting and Best Department of Medical Research, University of Toronto, Toronto, ON M5G 1L6, Canada
| | - Mathieu Blanchette
- McGill Centre for Bioinformatics, McGill University, Montréal, QC H3A 2B4, Canada
| | - David H Price
- Biochemistry Department, University of Iowa, Iowa City, IA 52242-1109, USA
| | - Benoit Coulombe
- Laboratory of Gene Transcription and Proteomics Discovery Platform, Institut de recherches cliniques de Montréal, 110 avenue des Pins Ouest, Montréal, QC H2W 1R7, Canada.
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Gras S, Chaumont V, Fernandez B, Carpentier P, Charrier-Savournin F, Schmitt S, Pineau C, Flament D, Hecker A, Forterre P, Armengaud J, Housset D. Structural insights into a new homodimeric self-activated GTPase family. EMBO Rep 2007; 8:569-75. [PMID: 17468740 PMCID: PMC2002535 DOI: 10.1038/sj.embor.7400958] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2006] [Revised: 01/25/2007] [Accepted: 02/28/2007] [Indexed: 11/09/2022] Open
Abstract
The human XAB1/MBDin GTPase and its close homologues form one of the ten phylogenetically distinct families of the SIMIBI (after signal recognition particle, MinD and BioD) class of phosphate-binding loop NTPases. The genomic context and the partners identified for the archaeal and eukaryotic homologues indicate that they are involved in genome maintenance--DNA repair or replication. The crystal structure of PAB0955 from Pyrococcus abyssi shows that, unlike other SIMIBI class G proteins, these highly conserved GTPases are homodimeric, regardless of the presence of nucleotides. The nucleotide-binding site of PAB0955 is rather rigid and its conformation is closest to that of the activated SRP G domain. One insertion to the G domain bears a strictly conserved GPN motif, which is part of the catalytic site of the other monomer and stabilizes the phosphate ion formed. Owing to this unique functional feature, we propose to call this family as GPN-loop GTPase.
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Affiliation(s)
- Stéphanie Gras
- Laboratoire de Cristallographie et Cristallogénèse des Protéines, Institut de Biologie Structurale J.-P. Ebel, CEA-CNRS-UJF, UMR 5075, 41, Rue Jules Horowitz, F-38027 Grenoble, France
| | - Valérie Chaumont
- Laboratoire de Biochimie des Systèmes Perturbés, Service de Biochimie et Toxicologie Nucléaire, Institut de Biologie Environnementale et Biotechnologie, CEA-VALRHO, Marcoule, BP 17171, F-30207 Bagnols sur Cèze, France
| | - Bernard Fernandez
- Laboratoire de Biochimie des Systèmes Perturbés, Service de Biochimie et Toxicologie Nucléaire, Institut de Biologie Environnementale et Biotechnologie, CEA-VALRHO, Marcoule, BP 17171, F-30207 Bagnols sur Cèze, France
| | - Philippe Carpentier
- Laboratoire de Cristallographie et Cristallogénèse des Protéines, Institut de Biologie Structurale J.-P. Ebel, CEA-CNRS-UJF, UMR 5075, 41, Rue Jules Horowitz, F-38027 Grenoble, France
| | - Fabienne Charrier-Savournin
- Laboratoire de Biochimie des Systèmes Perturbés, Service de Biochimie et Toxicologie Nucléaire, Institut de Biologie Environnementale et Biotechnologie, CEA-VALRHO, Marcoule, BP 17171, F-30207 Bagnols sur Cèze, France
| | - Sophie Schmitt
- Laboratoire de Microbiologie des Environnements Extrêmes, UMR6197, IFREMER-Centre de Brest, BP 70, F-29280 Plouzané cedex, France
| | - Charles Pineau
- INSERM, U625, UPRES JE 2459, Campus de Beaulieu, Rennes F-35042, France
| | - Didier Flament
- Laboratoire de Microbiologie des Environnements Extrêmes, UMR6197, IFREMER-Centre de Brest, BP 70, F-29280 Plouzané cedex, France
| | - Arnaud Hecker
- UMR CNRS/Université Paris-Sud 8621, Institut de Génétique et de Microbiologie – Bât. 409, F-91405 Orsay cedex, France
| | - Patrick Forterre
- UMR CNRS/Université Paris-Sud 8621, Institut de Génétique et de Microbiologie – Bât. 409, F-91405 Orsay cedex, France
- Laboratoire de Microbiologie et de Biotechnologie des Extremophiles, Département de Microbiologie Fondamentale et Médicale, Institut Pasteur, 28 Rue du Dr Roux, F-75724 Paris cedex 15, France
| | - Jean Armengaud
- Laboratoire de Biochimie des Systèmes Perturbés, Service de Biochimie et Toxicologie Nucléaire, Institut de Biologie Environnementale et Biotechnologie, CEA-VALRHO, Marcoule, BP 17171, F-30207 Bagnols sur Cèze, France
| | - Dominique Housset
- Laboratoire de Cristallographie et Cristallogénèse des Protéines, Institut de Biologie Structurale J.-P. Ebel, CEA-CNRS-UJF, UMR 5075, 41, Rue Jules Horowitz, F-38027 Grenoble, France
- Tel: +33 4 76 20 94 69; Fax: +33 4 38 78 51 22; E-mail:
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D'Alessio AC, Szyf M. Epigenetic tête-à-tête: the bilateral relationship between chromatin modifications and DNA methylation. Biochem Cell Biol 2007; 84:463-76. [PMID: 16936820 DOI: 10.1139/o06-090] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The epigenome, which comprises chromatin, associated proteins, and the pattern of covalent modification of DNA by methylation, sets up and maintains gene expression programs. It was originally believed that DNA methylation was the dominant reaction in determining the chromatin structure. However, emerging data suggest that chromatin can affect DNA methylation in both directions, triggering either de novo DNA methylation or demethylation. These events are particularly important for the understanding of cellular transformation, which requires a coordinated change in gene expression profiles. While genetic alterations can explain some of the changes, the important role of epigenetic reprogramming is becoming more and more evident. Cancer cells exhibit a paradoxical coexistence of global loss of DNA methylation with regional hypermethylation.
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Affiliation(s)
- Ana C D'Alessio
- Department of Pharmacology and Therapeutics, McGill University, 3655 Promenade Sir William Osler, Montreal, QC H3G 1Y6, Canada
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31
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Angrisano T, Lembo F, Pero R, Natale F, Fusco A, Avvedimento VE, Bruni CB, Chiariotti L. TACC3 mediates the association of MBD2 with histone acetyltransferases and relieves transcriptional repression of methylated promoters. Nucleic Acids Res 2006; 34:364-72. [PMID: 16410616 PMCID: PMC1331987 DOI: 10.1093/nar/gkj400] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We have recently reported that a novel MBD2 interactor (MBDin) has the capacity to reactivate transcription from MBD2-repressed methylated promoters even in the absence of demethylation events. Here we show that another unrelated protein, TACC3, displays a similar activity on methylated genes. In addition the data reported here provide possible molecular mechanisms for the observed phenomenon. Immunoprecipitation experiments showed that MBD2/TACC3 form a complex in vivo with the histone acetyltransferase pCAF. MBD2 could also associate with HDAC2, a component of MeCP1 repression complex. However, we found that the complexes formed by MBD2 with TACC3/pCAF and with HDAC2 were mutually exclusive. Moreover, HAT enzymatic assays demonstrated that HAT activity associates with MBD2 in vivo and that such association significantly increased when TACC3 was over-expressed. Overall our findings suggest that TACC3 can be recruited by MBD2 on methylated promoters and is able to reactivate transcription possibly by favoring the formation of an HAT-containing MBD2 complex and, thus, switching the repression potential of MBD2 in activation even prior to eventual demethylation.
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Affiliation(s)
- Tiziana Angrisano
- Dipartimento di Biologia e Patologia Cellulare e Molecolare ‘L. Califano’, Università degli Studi di Napoli ‘Federico II’80131 Naples, Italy
| | - Francesca Lembo
- Dipartimento di Chimica Farmaceutica e Tossicologica, Università degli Studi di Napoli ‘Federico II’80131 Naples, Italy
| | - Raffaela Pero
- Dipartimento di Biologia e Patologia Cellulare e Molecolare ‘L. Califano’, Università degli Studi di Napoli ‘Federico II’80131 Naples, Italy
| | - Francesco Natale
- Dipartimento di Biologia e Patologia Cellulare e Molecolare ‘L. Califano’, Università degli Studi di Napoli ‘Federico II’80131 Naples, Italy
| | - Alfredo Fusco
- Dipartimento di Biologia e Patologia Cellulare e Molecolare ‘L. Califano’, Università degli Studi di Napoli ‘Federico II’80131 Naples, Italy
- NOGEC, Naples Oncogenomic Center, CEINGE Biotecnologie AvanzateNaples, Italy
| | - Vittorio E. Avvedimento
- Dipartimento di Biologia e Patologia Cellulare e Molecolare ‘L. Califano’, Università degli Studi di Napoli ‘Federico II’80131 Naples, Italy
- NOGEC, Naples Oncogenomic Center, CEINGE Biotecnologie AvanzateNaples, Italy
| | - Carmelo B. Bruni
- Dipartimento di Biologia e Patologia Cellulare e Molecolare ‘L. Califano’, Università degli Studi di Napoli ‘Federico II’80131 Naples, Italy
| | - Lorenzo Chiariotti
- Dipartimento di Biologia e Patologia Cellulare e Molecolare ‘L. Califano’, Università degli Studi di Napoli ‘Federico II’80131 Naples, Italy
- Dipartimento di Scienze per la Salute, Università degli Studi del Molise86100 Campobasso, Italy
- NOGEC, Naples Oncogenomic Center, CEINGE Biotecnologie AvanzateNaples, Italy
- To whom correspondence should be addressed. Tel: +39 081 7462056; Fax: +39 081 7703285;
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Fan J, Kodama EI, Koh Y, Nakao M, Matsuoka M. Halogenated thymidine analogues restore the expression of silenced genes without demethylation. Cancer Res 2005; 65:6927-33. [PMID: 16061677 DOI: 10.1158/0008-5472.can-04-3495] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Transcriptional silencing of tumor suppressor genes by aberrant DNA methylation is a characteristic frequently observed in cancer cells. Therefore, reversing this process is a therapeutic target against cancer. In this study, we established a screening system for silencing inhibitors with cell lines transfected by a retroviral vector containing a luciferase gene. More than 100 nucleosides were tested for antisilencing activity with a selected clone in which the silenced expression of luciferase could be recovered by 5-aza-2'-deoxycytidine. A group of halogenated thymidine analogues was found to reactivate transcription of not only the reporter retrovirus vector but also endogenous glutathione-S-transferase 1 gene, without influence to DNA hypermethylation. Gel mobility shift assay showed that 5-bromo-2'-deoxyuridine (BrdUrd) or 5-iodo-2'-deoxyuridine incorporation did not affect the binding of the methyl-CpG binding protein motif to methylated DNA. Finally, in the retroviral promoter, BrdUrd treatment increased the acetylated histone H3 level and decreased methylation of histone H3 Lys9 in accordance with recovered transcription. This study shows that halogenated thymidines have an antisilencing effect without changing DNA methylation status by interfering with step(s) between DNA methylation and histone acetylation.
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Affiliation(s)
- Jun Fan
- Laboratory of Virus Immunology, Institute for Virus Research, Kyoto University, Kyoto, Japan
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33
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Niesen MI, Osborne AR, Yang H, Rastogi S, Chellappan S, Cheng JQ, Boss JM, Blanck G. Activation of a methylated promoter mediated by a sequence-specific DNA-binding protein, RFX. J Biol Chem 2005; 280:38914-22. [PMID: 16166088 DOI: 10.1074/jbc.m504633200] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The roles of eukaryotic DNA methylation in the repression of mRNA transcription and in the formation of heterochromatin have been extensively elucidated over the past several years. However, the role of DNA methylation in transcriptional activation remains a mystery. In particular, it is not known whether the transcriptional activation of methylated DNA is promoter-specific, depends directly on sequence-specific DNA-binding proteins, or is facilitated by the methylation. Here we report that the sequence-specific DNA-binding protein, RFX, previously shown to mediate the transition from an inactive to an active chromatin structure, activates a methylated promoter. RFX is capable of mediating enhanceosome formation on a methylated promoter, thereby mediating a transition from a methylation-dependent repression of the promoter to a methylation-dependent activation of the promoter. These results indicate novel roles for DNA methylation and sequence-specific DNA-binding proteins in transcriptional activation.
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Affiliation(s)
- Melissa I Niesen
- Department of Biochemistry and Molecular Biology, College of Medicine, University of South Florida, Tampa, Florida 33612, USA
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34
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Ballestar E, Esteller M. Methyl-CpG-binding proteins in cancer: blaming the DNA methylation messenger. Biochem Cell Biol 2005; 83:374-84. [PMID: 15959563 DOI: 10.1139/o05-035] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
In recent years, epigenetic alterations have come to prominence in cancer research. In particular, hypermethylation of CpG islands located in the promoter regions of tumor-suppressor genes is now firmly established as an important mechanism for gene inactivation in cancer. One of the most remarkable achievements in the field has been the identification of the methyl-CpG-binding domain family of proteins, which provide mechanistic links between specific patterns of DNA methylation and histone modifications. Although many of the current data indicate that methyl-CpG-binding proteins play a key role in maintaining a transcriptionally inactive state of methylated genes, MBD4 is also known to be involved in excision repair of T:G mismatches. The latter is a member of this family of proteins and appears to play a role in reducing mutations at 5-methylcytosine. This review examines the contribution of methyl-CpG-binding proteins in the epigenetic pathway of cancer.Key words: methyl-CpG-binding, MeCP2, DNA methylation, Rett syndrome, cancer epigenetics.
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Affiliation(s)
- Esteban Ballestar
- Cancer Epigenetics Laboratory, Spanish National Cancer Centre, Madrid, Spain
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35
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Matarazzo MR, Lembo F, Angrisano T, Ballestar E, Ferraro M, Pero R, De Bonis ML, Bruni CB, Esteller M, D'Esposito M, Chiariotti L. In vivo analysis of DNA methylation patterns recognized by specific proteins: coupling CHIP and bisulfite analysis. Biotechniques 2005; 37:666-8, 670, 672-3. [PMID: 15517979 DOI: 10.2144/04374dd02] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
The three-way connection between DNA methylation, chromatin configuration, and transcriptional regulation is under increasing attention, but the fine rules governing the epigenetic control are still poorly understood. In several studies, the authors have concluded that the methylation status of CpG sites could be critical for the binding of factors to DNA and, consequently, for chromatin conformation. We tested the possibility that a novel technical approach combining chromatin immunoprecipitation and bisulfite genomic sequencing analysis (ChIP-BA) could provide useful information on the role of specific CpG methylation patterns in driving the association in vivo of proteins to given genomic regions. Our results show that ChIP-BA permits the establishment in vivo of the methylation patterns required for the binding of a methyl-CpG binding protein and, in addition, can potentially identify methylation patterns that do not allow a protein to bind specific genomic regions. Possible fields of application are discussed. We believe that wide use of ChIP-BA could make possible the exploration of a novel aspect of the intricate epigenetic web.
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36
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Uno T, Nomura Y, Nakamura M, Nakao A, Tajima S, Kanamaru K, Yamagata H, Iwanaga Y. Expression, purification and characterization of methyl DNA binding protein from Bombyx mori. JOURNAL OF INSECT SCIENCE (ONLINE) 2005; 5:8. [PMID: 16299598 PMCID: PMC1283889 DOI: 10.1093/jis/5.1.8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2004] [Accepted: 10/09/2004] [Indexed: 05/01/2023]
Abstract
A cDNA clone encoding methyl DNA binding domain-containing protein (bMBD2/3) was obtained by homology searches using a Bombyx mori fat body cDNA library. The cDNA encoded a polypeptide with 249 amino acids sharing 54% similarity with the methyl DNA binding protein from Drosophila melanogaster. To characterize the biochemical properties of bMBD2/3, the clone was expressed in Escherichia coli as His-tagged protein. The recombinant protein was purified to homogeneity using Ni-NTA superflow resin and heparin agarose. The protein showed specific methyl DNA binding activity and was phosphorylated by protein kinase in vitro. Immunoblotting using the purified antibody indicated that bMBD2/3 was expressed in almost all tissues. Using west-western blotting analysis, some proteins that interact with bMBD2/3 were identified in the brain. This is the first report that insect MBD is phosphorylated and is present in adult tissues. These results suggest that bMBD2/3 plays important roles in the DNA methylation-specific transcription of Bombyx mori.
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Affiliation(s)
- Tomohide Uno
- Laboratory of Biological Chemistry, Department of Biofunctional Chemistry, Faculty of Agriculture, Kobe University, Nada-ku, Kobe, Hyogo, 657-8501, Japan.
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Fitzpatrick DR, Wilson CB. Methylation and demethylation in the regulation of genes, cells, and responses in the immune system. Clin Immunol 2003; 109:37-45. [PMID: 14585274 DOI: 10.1016/s1521-6616(03)00205-5] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
DNA methylation is a focus of epigenetic research in the immune system. This overview begins with a synopsis of the players and processes involved in DNA methylation, demethylation, methyl-CpG-recognition, histone modification, and chromatin remodeling. The role of these mechanisms in immune responses, with a focus on T lymphocytes, is then reviewed. There is evidence for epigenetic regulation of several key immune processes including thymocyte development, antigen presentation, differentiation, cytokine expression, effector function, and memory. DNA methylation contributes, along with other epigenetic mechanisms, to the establishment of transcriptional thresholds that vary between genes and T cell types. The immune system is a fertile field for studies of epigenetic regulation of cell fate and function.
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Affiliation(s)
- David R Fitzpatrick
- Immunological Systems Department, Amgen Inc, 51 University St, Seattle, WA 98101, USA.
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