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Smith PR, Pandit SC, Loerch S, Campbell ZT. The space between notes: emerging roles for translationally silent ribosomes. Trends Biochem Sci 2022; 47:477-491. [PMID: 35246374 PMCID: PMC9106873 DOI: 10.1016/j.tibs.2022.02.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 01/31/2022] [Accepted: 02/04/2022] [Indexed: 01/02/2023]
Abstract
In addition to their central functions in translation, ribosomes can adopt inactive structures that are fully assembled yet devoid of mRNA. We describe how the abundance of idle eukaryotic ribosomes is influenced by a broad range of biological conditions spanning viral infection, nutrient deprivation, and developmental cues. Vacant ribosomes may provide a means to exclude ribosomes from translation while also shielding them from degradation, and the variable identity of factors that occlude ribosomes may impart distinct functionality. We propose that regulated changes in the balance of idle and active ribosomes provides a means to fine-tune translation. We provide an overview of idle ribosomes, describe what is known regarding their function, and highlight questions that may clarify their biological roles.
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Affiliation(s)
- Patrick R Smith
- The University of Texas at Dallas, Department of Biological Sciences, Richardson, TX, USA
| | - Sapna C Pandit
- University of California, Santa Cruz, Department of Chemistry and Biochemistry, Santa Cruz, CA, USA
| | - Sarah Loerch
- University of California, Santa Cruz, Department of Chemistry and Biochemistry, Santa Cruz, CA, USA
| | - Zachary T Campbell
- The University of Texas at Dallas, Department of Biological Sciences, Richardson, TX, USA; The Center for Advanced Pain Studies (CAPS), University of Texas at Dallas, Richardson, TX, USA.
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2
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Chiu SC, Huang YRJ, Wei TYW, Chen JMM, Kuo YC, Huang YTJ, Liao YTA, Yu CTR. The PRMT5/HURP axis retards Golgi repositioning by stabilizing acetyl-tubulin and Golgi apparatus during cell migration. J Cell Physiol 2021; 237:1033-1043. [PMID: 34541678 DOI: 10.1002/jcp.30589] [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] [Received: 06/02/2021] [Revised: 08/29/2021] [Accepted: 08/31/2021] [Indexed: 11/10/2022]
Abstract
The Golgi apparatus (GA) translocates to the cell leading end during directional migration, thereby determining cell polarity and transporting essential factors to the migration apparatus. The study provides mechanistic insights into how GA repositioning (GR) is regulated. We show that the methyltransferase PRMT5 methylates the microtubule regulator HURP at R122. The HURP methylation mimicking mutant 122F impairs GR and cell migration. Mechanistic studies revealed that HURP 122F or endogenous methylated HURP, that is, HURP m122, interacts with acetyl-tubulin. Overexpression of HURP 122F stabilizes the bundling pattern of acetyl-tubulin by decreasing the sensitivity of the latter to a microtubule disrupting agent nocodazole. HURP 122F also rigidifies GA via desensitizing the organelle to several GA disrupting chemicals. Similarly, the acetyl-tubulin mimicking mutant 40Q or tubulin acetyltransferase αTAT1 can rigidify GA, impair GR, and retard cell migration. Reversal of HURP 122F-induced GA rigidification, by knocking down GA assembly factors such as GRASP65 or GM130, attenuates 122F-triggered GR and cell migration. Remarkably, PRMT5 is found downregulated and the level of HURP m122 is decreased during the early hours of wound healing-based cell migration, collectively implying that the PRMT5-HURP-acetyl-tubulin axis plays the role of brake, preventing GR and cell migration before cells reach empty space.
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Affiliation(s)
- Shao-Chih Chiu
- Graduate Institute of Biomedical Sciences, China Medical University, Taichung, Taiwan.,Department of Medical Research, Translational Cell Therapy Center, China Medical University Hospital, Taichung, Taiwan
| | | | - Tong-You Wade Wei
- Graduate Institute of Biomedicine and Biomedical Technology, National Chi Nan University, Nantou, Taiwan.,Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Jo-Mei Maureen Chen
- Department of Applied Chemistry, National Chi Nan University, Nantou, Taiwan
| | - Yi-Chun Kuo
- Graduate Institute of Biomedicine and Biomedical Technology, National Chi Nan University, Nantou, Taiwan
| | - Yu-Ting Jenny Huang
- Department of Applied Chemistry, National Chi Nan University, Nantou, Taiwan
| | - Yu-Ting Amber Liao
- Department of Applied Chemistry, National Chi Nan University, Nantou, Taiwan
| | - Chang-Tze Ricky Yu
- Department of Applied Chemistry, National Chi Nan University, Nantou, Taiwan.,Graduate Institute of Biomedicine and Biomedical Technology, National Chi Nan University, Nantou, Taiwan
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3
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Halabelian L, Barsyte-Lovejoy D. Structure and Function of Protein Arginine Methyltransferase PRMT7. Life (Basel) 2021; 11:768. [PMID: 34440512 PMCID: PMC8399567 DOI: 10.3390/life11080768] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Revised: 07/28/2021] [Accepted: 07/28/2021] [Indexed: 01/06/2023] Open
Abstract
PRMT7 is a member of the protein arginine methyltransferase (PRMT) family, which methylates a diverse set of substrates. Arginine methylation as a posttranslational modification regulates protein-protein and protein-nucleic acid interactions, and as such, has been implicated in various biological functions. PRMT7 is a unique, evolutionarily conserved PRMT family member that catalyzes the mono-methylation of arginine. The structural features, functional aspects, and compounds that inhibit PRMT7 are discussed here. Several studies have identified physiological substrates of PRMT7 and investigated the substrate methylation outcomes which link PRMT7 activity to the stress response and RNA biology. PRMT7-driven substrate methylation further leads to the biological outcomes of gene expression regulation, cell stemness, stress response, and cancer-associated phenotypes such as cell migration. Furthermore, organismal level phenotypes of PRMT7 deficiency have uncovered roles in muscle cell physiology, B cell biology, immunity, and brain function. This rapidly growing information on PRMT7 function indicates the critical nature of context-dependent functions of PRMT7 and necessitates further investigation of the PRMT7 interaction partners and factors that control PRMT7 expression and levels. Thus, PRMT7 is an important cellular regulator of arginine methylation in health and disease.
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Affiliation(s)
- Levon Halabelian
- Structural Genomics Consortium, Temerty Faculty of Medicine, University of Toronto, Toronto, ON M5S 1A8, Canada;
| | - Dalia Barsyte-Lovejoy
- Structural Genomics Consortium, Temerty Faculty of Medicine, University of Toronto, Toronto, ON M5S 1A8, Canada;
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, ON M5S 1A8, Canada
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4
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İNANDIKLIOGLU N, DEMİRHAN O, BAYRAM İ, TANYELİ A. Çukurova Bölgesinde akut lenfoblastik lösemili çocuklarda vasküler endotelyal büyüme faktörü (VEGF-C) ve temel fibroblast büyüme faktörü (bFGF) plazma ekspresyonu ve metilasyon seviyeleri. CUKUROVA MEDICAL JOURNAL 2020. [DOI: 10.17826/cumj.676515] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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5
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Jain K, Clarke SG. PRMT7 as a unique member of the protein arginine methyltransferase family: A review. Arch Biochem Biophys 2019; 665:36-45. [PMID: 30802433 PMCID: PMC6461449 DOI: 10.1016/j.abb.2019.02.014] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2019] [Revised: 02/16/2019] [Accepted: 02/18/2019] [Indexed: 12/14/2022]
Abstract
Protein arginine methyltransferases (PRMTs) are found in a wide variety of eukaryotic organisms and can regulate gene expression, DNA repair, RNA splicing, and stem cell biology. In mammalian cells, nine genes encode a family of sequence-related enzymes; six of these PRMTs catalyze the formation of ω-asymmetric dimethyl derivatives, two catalyze ω-symmetric dimethyl derivatives, and only one (PRMT7) solely catalyzes ω-monomethylarginine formation. Purified recombinant PRMT7 displays a number of unique enzymatic properties including a substrate preference for arginine residues in R-X-R motifs with additional flanking basic amino acid residues and a temperature optimum well below 37 °C. Evidence has been presented for crosstalk between PRMT7 and PRMT5, where methylation of a histone H4 peptide at R17, a PRMT7 substrate, may activate PRMT5 for methylation of R3. Defects in muscle stem cells (satellite cells) and immune cells are found in mouse Prmt7 homozygous knockouts, while humans lacking PRMT7 are characterized by significant intellectual developmental delays, hypotonia, and facial dysmorphisms. The overexpression of the PRMT7 gene has been correlated with cancer metastasis in humans. Current research challenges include identifying cellular factors that control PRMT7 expression and activity, identifying the physiological substrates of PRMT7, and determining the effect of methylation on these substrates.
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Affiliation(s)
- Kanishk Jain
- Lineberger Comprehensive Cancer Center and Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, School of Medicine, Chapel Hill, NC, 27599, USA
| | - Steven G Clarke
- Department of Chemistry and Biochemistry and the Molecular Biology Institute, University of California, Los Angeles, CA, 90095, USA.
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6
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Haghandish N, Baldwin RM, Morettin A, Dawit HT, Adhikary H, Masson JY, Mazroui R, Trinkle-Mulcahy L, Côté J. PRMT7 methylates eukaryotic translation initiation factor 2α and regulates its role in stress granule formation. Mol Biol Cell 2019; 30:778-793. [PMID: 30699057 PMCID: PMC6589776 DOI: 10.1091/mbc.e18-05-0330] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Protein arginine methyltransferases (PRMTs) are a family of enzymes that modify proteins by methylating the guanidino nitrogen atoms of arginine residues to regulate cellular processes such as chromatin remodeling, pre-mRNA splicing, and signal transduction. PRMT7 is the single type III PRMT solely capable of arginine monomethylation. To date, other than histone proteins, there are very few identified substrates of PRMT7. We therefore performed quantitative mass spectrometry experiments to identify PRMT7’s interactome and potential substrates to better characterize the enzyme’s biological function(s) in cells. These experiments revealed that PRMT7 interacts with and can methylate eukaryotic translation initiation factor 2 alpha (eIF2α), in vitro and in breast cancer cells. Furthermore, we uncovered a potential regulatory interplay between eIF2α arginine methylation by PRMT7 and stress-induced phosphorylation status of eIF2α at serine 51. Finally, we demonstrated that PRMT7 is required for eIF2α-dependent stress granule formation in the face of various cellular stresses. Altogether, our findings implicate PRMT7 as a novel mediator of eIF2α-dependent cellular stress response pathways.
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Affiliation(s)
- Nasim Haghandish
- Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
| | - R Mitchell Baldwin
- Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
| | - Alan Morettin
- Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
| | - Haben Tesfu Dawit
- Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
| | - Hemanta Adhikary
- Oncology Division, CHU de Québec-Université Laval, Québec City, QC G1R 3S3, Canada.,Department of Molecular Biology, Medical Biochemistry and Pathology, Laval University Cancer Research Center, Québec City, QC G1V 0A6, Canada
| | - Jean-Yves Masson
- Oncology Division, CHU de Québec-Université Laval, Québec City, QC G1R 3S3, Canada.,Department of Molecular Biology, Medical Biochemistry and Pathology, Laval University Cancer Research Center, Québec City, QC G1V 0A6, Canada
| | - Rachid Mazroui
- Oncology Division, CHU de Québec-Université Laval, Québec City, QC G1R 3S3, Canada.,Department of Molecular Biology, Medical Biochemistry and Pathology, Laval University Cancer Research Center, Québec City, QC G1V 0A6, Canada
| | - Laura Trinkle-Mulcahy
- Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
| | - Jocelyn Côté
- Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
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7
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PRMT7 Interacts with ASS1 and Citrullinemia Mutations Disrupt the Interaction. J Mol Biol 2017; 429:2278-2289. [DOI: 10.1016/j.jmb.2017.05.026] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2017] [Revised: 05/25/2017] [Accepted: 05/31/2017] [Indexed: 11/23/2022]
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8
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Cura V, Troffer-Charlier N, Wurtz JM, Bonnefond L, Cavarelli J. Structural insight into arginine methylation by the mouse protein arginine methyltransferase 7: a zinc finger freezes the mimic of the dimeric state into a single active site. ACTA ACUST UNITED AC 2014; 70:2401-12. [PMID: 25195753 DOI: 10.1107/s1399004714014278] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2014] [Accepted: 06/18/2014] [Indexed: 01/18/2023]
Abstract
Protein arginine methyltransferase 7 (PRMT7) is a type III arginine methyltransferase which has been implicated in several biological processes such as transcriptional regulation, DNA damage repair, RNA splicing, cell differentiation and metastasis. PRMT7 is a unique but less characterized member of the family of PRMTs. The crystal structure of full-length PRMT7 from Mus musculus refined at 1.7 Å resolution is described. The PRMT7 structure is composed of two catalytic modules in tandem forming a pseudo-dimer and contains only one AdoHcy molecule bound to the N-terminal module. The high-resolution crystal structure presented here revealed several structural features showing that the second active site is frozen in an inactive state by a conserved zinc finger located at the junction between the two PRMT modules and by the collapse of two degenerated AdoMet-binding loops.
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Affiliation(s)
- Vincent Cura
- Département de Biologie Structurale Intégrative, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Université de Strasbourg, CNRS UMR7104, INSERM U596, 1 Rue Laurent Fries, F-67404 Illkirch, France
| | - Nathalie Troffer-Charlier
- Département de Biologie Structurale Intégrative, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Université de Strasbourg, CNRS UMR7104, INSERM U596, 1 Rue Laurent Fries, F-67404 Illkirch, France
| | - Jean Marie Wurtz
- Département de Biologie Structurale Intégrative, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Université de Strasbourg, CNRS UMR7104, INSERM U596, 1 Rue Laurent Fries, F-67404 Illkirch, France
| | - Luc Bonnefond
- Département de Biologie Structurale Intégrative, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Université de Strasbourg, CNRS UMR7104, INSERM U596, 1 Rue Laurent Fries, F-67404 Illkirch, France
| | - Jean Cavarelli
- Département de Biologie Structurale Intégrative, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Université de Strasbourg, CNRS UMR7104, INSERM U596, 1 Rue Laurent Fries, F-67404 Illkirch, France
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9
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Cura V, Troffer-Charlier N, Lambert MA, Bonnefond L, Cavarelli J. Cloning, expression, purification and preliminary X-ray crystallographic analysis of mouse protein arginine methyltransferase 7. Acta Crystallogr F Struct Biol Commun 2014; 70:80-6. [PMID: 24419624 PMCID: PMC3943109 DOI: 10.1107/s2053230x13032871] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2013] [Accepted: 12/03/2013] [Indexed: 11/10/2022] Open
Abstract
Protein arginine methyltransferase 7 (PRMT7) is a unique but less characterized member of the family of protein arginine methyltransferases (PRMTs) that plays a role in male germline gene imprinting. PRMT7 is the only known PRMT member that catalyzes the monomethylation but not the dimethylation of the target arginine residues and harbours two catalytic domains in tandem. PRMT7 genes from five different species were cloned and expressed in Escherichia coli and Sf21 insect cells. Four gave soluble proteins from Sf21 cells, of which two were homogeneous and one gave crystals. The mouse PRMT7 structure was solved by the single anomalous dispersion method using a crystal soaked with thimerosal that diffracted to beyond 2.1 Å resolution. The crystal belonged to space group P4(3)2(1)2, with unit-cell parameters a = b = 97.4, c = 168.1 Å and one PRMT7 monomer in the asymmetric unit. The structure of another crystal form belonging to space group I222 was solved by molecular replacement.
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Affiliation(s)
- Vincent Cura
- Département de Biologie Structurale Intégrative, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U964/CNRS UMR 7104/Université de Strasbourg, 1 Rue Laurent Fries, 67404 Illkirch, France
| | - Nathalie Troffer-Charlier
- Département de Biologie Structurale Intégrative, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U964/CNRS UMR 7104/Université de Strasbourg, 1 Rue Laurent Fries, 67404 Illkirch, France
| | - Marie-Annick Lambert
- Département de Biologie Structurale Intégrative, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U964/CNRS UMR 7104/Université de Strasbourg, 1 Rue Laurent Fries, 67404 Illkirch, France
| | - Luc Bonnefond
- Département de Biologie Structurale Intégrative, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U964/CNRS UMR 7104/Université de Strasbourg, 1 Rue Laurent Fries, 67404 Illkirch, France
| | - Jean Cavarelli
- Département de Biologie Structurale Intégrative, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U964/CNRS UMR 7104/Université de Strasbourg, 1 Rue Laurent Fries, 67404 Illkirch, France
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10
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Nicholas C, Yang J, Peters SB, Bill MA, Baiocchi RA, Yan F, Sïf S, Tae S, Gaudio E, Wu X, Grever MR, Young GS, Lesinski GB. PRMT5 is upregulated in malignant and metastatic melanoma and regulates expression of MITF and p27(Kip1.). PLoS One 2013; 8:e74710. [PMID: 24098663 PMCID: PMC3786975 DOI: 10.1371/journal.pone.0074710] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2013] [Accepted: 08/05/2013] [Indexed: 12/16/2022] Open
Abstract
Protein arginine methyltransferase-5 (PRMT5) is a Type II arginine methyltransferase that regulates various cellular functions. We hypothesized that PRMT5 plays a role in regulating the growth of human melanoma cells. Immunohistochemical analysis indicated significant upregulation of PRMT5 in human melanocytic nevi, malignant melanomas and metastatic melanomas as compared to normal epidermis. Furthermore, nuclear PRMT5 was significantly decreased in metastatic melanomas as compared to primary cutaneous melanomas. In human metastatic melanoma cell lines, PRMT5 was predominantly cytoplasmic, and associated with its enzymatic cofactor Mep50, but not STAT3 or cyclin D1. However, histologic examination of tumor xenografts from athymic mice revealed heterogeneous nuclear and cytoplasmic PRMT5 expression. Depletion of PRMT5 via siRNA inhibited proliferation in a subset of melanoma cell lines, while it accelerated growth of others. Loss of PRMT5 also led to reduced expression of MITF (microphthalmia-associated transcription factor), a melanocyte-lineage specific oncogene, and increased expression of the cell cycle regulator p27Kip1. These results are the first to report elevated PRMT5 expression in human melanoma specimens and indicate this protein may regulate MITF and p27Kip1 expression in human melanoma cells.
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Affiliation(s)
- Courtney Nicholas
- Department of Internal Medicine, Division of Medical Oncology, The Ohio State University Comprehensive Cancer Center, Columbus, Ohio, United States of America
| | - Jennifer Yang
- Department of Internal Medicine, Division of Medical Oncology, The Ohio State University Comprehensive Cancer Center, Columbus, Ohio, United States of America
| | - Sara B. Peters
- Department of Pathology, Division of Dermatopathology, The Ohio State University Comprehensive Cancer Center, Columbus, Ohio, United States of America
| | - Matthew A. Bill
- Department of Internal Medicine, Division of Medical Oncology, The Ohio State University Comprehensive Cancer Center, Columbus, Ohio, United States of America
| | - Robert A. Baiocchi
- Department of Internal Medicine, Division of Hematology, The Ohio State University Comprehensive Cancer Center, Columbus, Ohio, United States of America
| | - Fengting Yan
- Department of Internal Medicine, Division of Hematology, The Ohio State University Comprehensive Cancer Center, Columbus, Ohio, United States of America
| | - Saïd Sïf
- Department of Molecular and Cellular Biochemistry, The Ohio State University, Columbus, Ohio, United States of America
| | - Sookil Tae
- Department of Molecular and Cellular Biochemistry, The Ohio State University, Columbus, Ohio, United States of America
| | - Eugenio Gaudio
- Department of Molecular Virology, Immunology and Medical Genetics, The Ohio State University, Columbus, Ohio, United States of America
| | - Xin Wu
- The Ohio State University Comprehensive Cancer Center, Columbus, Ohio, United States of America
| | - Michael R. Grever
- Department of Internal Medicine, Division of Hematology, The Ohio State University Comprehensive Cancer Center, Columbus, Ohio, United States of America
| | - Gregory S. Young
- Center for Biostatistics, Arthur G. James Cancer Hospital and Richard J. Solove Research Institute, The Ohio State University, Columbus, Ohio, United States of America
| | - Gregory B. Lesinski
- Department of Internal Medicine, Division of Medical Oncology, The Ohio State University Comprehensive Cancer Center, Columbus, Ohio, United States of America
- * E-mail:
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11
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González-Terán B, Cortés JR, Manieri E, Matesanz N, Verdugo Á, Rodríguez ME, González-Rodríguez Á, Valverde ÁM, Valverde Á, Martín P, Davis RJ, Sabio G. Eukaryotic elongation factor 2 controls TNF-α translation in LPS-induced hepatitis. J Clin Invest 2012. [PMID: 23202732 DOI: 10.1172/jci65124] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Bacterial LPS (endotoxin) has been implicated in the pathogenesis of acute liver disease through its induction of the proinflammatory cytokine TNF-α. TNF-α is a key determinant of the outcome in a well-established mouse model of acute liver failure during septic shock. One possible mechanism for regulating TNF-α expression is through the control of protein elongation during translation, which would allow rapid cell adaptation to physiological changes. However, the regulation of translational elongation is poorly understood. We found that expression of p38γ/δ MAPK proteins is required for the elongation of nascent TNF-α protein in macrophages. The MKK3/6-p38γ/δ pathway mediated an inhibitory phosphorylation of eukaryotic elongation factor 2 (eEF2) kinase, which in turn promoted eEF2 activation (dephosphorylation) and subsequent TNF-α elongation. These results identify a new signaling pathway that regulates TNF-α production in LPS-induced liver damage and suggest potential cell-specific therapeutic targets for liver diseases in which TNF-α production is involved.
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Affiliation(s)
- Bárbara González-Terán
- Department of Vascular Biology and Inflammation, Fundación Centro Nacional de Investigaciones Cardiovasculares Carlos III, Madrid, Spain
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12
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Wei TYW, Juan CC, Hisa JY, Su LJ, Lee YCG, Chou HY, Chen JMM, Wu YC, Chiu SC, Hsu CP, Liu KL, Yu CTR. Protein arginine methyltransferase 5 is a potential oncoprotein that upregulates G1 cyclins/cyclin-dependent kinases and the phosphoinositide 3-kinase/AKT signaling cascade. Cancer Sci 2012; 103:1640-50. [PMID: 22726390 DOI: 10.1111/j.1349-7006.2012.02367.x] [Citation(s) in RCA: 150] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2012] [Revised: 05/29/2012] [Accepted: 06/05/2012] [Indexed: 11/30/2022] Open
Abstract
Increasing evidence suggests that PRMT5, a protein arginine methyltransferase, is involved in tumorigenesis. However, no systematic research has demonstrated the cell-transforming activity of PRMT5. We investigated the involvement of PRMT5 in tumor formation. First, we showed that PRMT5 was associated with many human cancers, through statistical analysis of microarray data in the NCBI GEO database. Overexpression of ectopic PRMT5 per se or its specific shRNA enhanced or reduced cell growth under conditions of normal or low concentrations of serum, low cell density, and poor cell attachment. A stable clone that expressed exogenous PRMT5 formed tumors in nude mice, which demonstrated that PRMT5 is a potential oncoprotein. PRMT5 accelerated cell cycle progression through G1 phase and modulated regulators of G1; for example, it upregulated cyclin-dependent kinase (CDK) 4, CDK6, and cyclins D1, D2 and E1, and inactivated retinoblastoma protein (Rb). Moreover, PRMT5 activated phosphoinositide 3-kinase (PI3K)/AKT and suppressed c-Jun N-terminal kinase (JNK)/c-Jun signaling cascades. However, only inhibition of PI3K activity, and not overexpression of JNK, blocked PRMT5-induced cell proliferation. Further analysis of PRMT5 expression in 64 samples of human lung cancer tissues by microarray and western blot analysis revealed a tight association of PRMT5 with lung cancer. Knockdown of PRMT5 retarded cell growth of lung cancer cell lines A549 and H1299. In conclusion, to the best of our knowledge, we have characterized the cell-transforming activity of PRMT5 and delineated its underlying mechanisms for the first time.
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Affiliation(s)
- Tong-You W Wei
- Graduate Institute of Biomedicine and Biomedical Technology, National Chi Nan University, Puli, Taiwan
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