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Romagnoli BAA, Holetz FB, Alves LR, Goldenberg S. RNA Binding Proteins and Gene Expression Regulation in Trypanosoma cruzi. Front Cell Infect Microbiol 2020; 10:56. [PMID: 32154189 PMCID: PMC7045066 DOI: 10.3389/fcimb.2020.00056] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Accepted: 02/03/2020] [Indexed: 01/24/2023] Open
Abstract
The regulation of gene expression in trypanosomatids occurs mainly at the post-transcriptional level. In the case of Trypanosoma cruzi, the characterization of messenger ribonucleoprotein (mRNP) particles has allowed the identification of several classes of RNA binding proteins (RBPs), as well as non-canonical RBPs, associated with mRNA molecules. The protein composition of the mRNPs as well as the localization and functionality of the mRNAs depend on their associated proteins. mRNPs can also be organized into larger complexes forming RNA granules, which function as stress granules or P-bodies depending on the associated proteins. The fate of mRNAs in the cell, and consequently the genes expressed, depends on the set of proteins associated with the messenger molecule. These proteins allow the coordinated expression of mRNAs encoding proteins that are related in function, resulting in the formation of post-transcriptional operons. However, the puzzle posed by the combinatorial association of sets of RBPs with mRNAs and how this relates to the expressed genes remain to be elucidated. One important tool in this endeavor is the use of the CRISPR/CAS system to delete genes encoding RBPs, allowing the evaluation of their effect on the formation of mRNP complexes and associated mRNAs in the different compartments of the translation machinery. Accordingly, we recently established this methodology for T. cruzi and deleted the genes encoding RBPs containing zinc finger domains. In this manuscript, we will discuss the data obtained and the potential of the CRISPR/CAS methodology to unveil the role of RBPs in T. cruzi gene expression regulation.
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Affiliation(s)
- Bruno A A Romagnoli
- Gene Expression Regulation Laboratory, Institute Carlos Chagas, Curitiba, Brazil
| | - Fabiola B Holetz
- Gene Expression Regulation Laboratory, Institute Carlos Chagas, Curitiba, Brazil
| | - Lysangela R Alves
- Gene Expression Regulation Laboratory, Institute Carlos Chagas, Curitiba, Brazil
| | - Samuel Goldenberg
- Gene Expression Regulation Laboratory, Institute Carlos Chagas, Curitiba, Brazil
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Zoltner M, Krienitz N, Field MC, Kramer S. Comparative proteomics of the two T. brucei PABPs suggests that PABP2 controls bulk mRNA. PLoS Negl Trop Dis 2018; 12:e0006679. [PMID: 30040867 PMCID: PMC6075789 DOI: 10.1371/journal.pntd.0006679] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Revised: 08/03/2018] [Accepted: 07/10/2018] [Indexed: 01/17/2023] Open
Abstract
Poly(A)-binding proteins (PABPs) regulate mRNA fate by controlling stability and translation through interactions with both the poly(A) tail and eIF4F complex. Many organisms have several paralogs of PABPs and eIF4F complex components and it is likely that different eIF4F/PABP complex combinations regulate distinct sets of mRNAs. Trypanosomes have five eIF4G paralogs, six of eIF4E and two PABPs, PABP1 and PABP2. Under starvation, polysomes dissociate and the majority of mRNAs, most translation initiation factors and PABP2 reversibly localise to starvation stress granules. To understand this more broadly we identified a protein interaction cohort for both T. brucei PABPs by cryo-mill/affinity purification-mass spectrometry. PABP1 very specifically interacts with the previously identified interactors eIF4E4 and eIF4G3 and few others. In contrast PABP2 is promiscuous, with a larger set of interactors including most translation initiation factors and most prominently eIF4G1, with its two partners TbG1-IP and TbG1-IP2. Only RBP23 was specific to PABP1, whilst 14 RNA-binding proteins were exclusively immunoprecipitated with PABP2. Significantly, PABP1 and associated proteins are largely excluded from starvation stress granules, but PABP2 and most interactors translocate to granules on starvation. We suggest that PABP1 regulates a small subpopulation of mainly small-sized mRNAs, as it interacts with a small and distinct set of proteins unable to enter the dominant pathway into starvation stress granules and localises preferentially to a subfraction of small polysomes. By contrast PABP2 likely regulates bulk mRNA translation, as it interacts with a wide range of proteins, enters stress granules and distributes over the full range of polysomes.
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Affiliation(s)
- Martin Zoltner
- School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Nina Krienitz
- School of Life Sciences, University of Dundee, Dundee, United Kingdom
- Department of Cell and Developmental Biology, Biocenter, University of Würzburg, Am Hubland, Würzburg, Germany
| | - Mark C. Field
- School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Susanne Kramer
- Department of Cell and Developmental Biology, Biocenter, University of Würzburg, Am Hubland, Würzburg, Germany
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Courel M, Bénard M, Ernoult-Lange M, Chouaib R, Hubstenberger A, Kress M, Weil D. [P-bodies: microscopic droplets to store mRNAs encoding regulatory proteins]. Med Sci (Paris) 2018; 34:306-308. [PMID: 29658471 DOI: 10.1051/medsci/20183404009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Maïté Courel
- Sorbonne université, CNRS, institut de biologie Paris-Seine (IBPS), Laboratoire de biologie du développement, 7, quai Saint Bernard, F-75005 Paris, France
| | - Marianne Bénard
- Sorbonne université, CNRS, institut de biologie Paris-Seine (IBPS), Laboratoire de biologie du développement, 7, quai Saint Bernard, F-75005 Paris, France
| | - Michèle Ernoult-Lange
- Sorbonne université, CNRS, institut de biologie Paris-Seine (IBPS), Laboratoire de biologie du développement, 7, quai Saint Bernard, F-75005 Paris, France
| | - Racha Chouaib
- Sorbonne université, CNRS, institut de biologie Paris-Seine (IBPS), Laboratoire de biologie du développement, 7, quai Saint Bernard, F-75005 Paris, France - Département de biologie, faculté de sciences, université du Liban, Beyrouth, Liban
| | - Arnaud Hubstenberger
- Sorbonne université, CNRS, institut de biologie Paris-Seine (IBPS), Laboratoire de biologie du développement, 7, quai Saint Bernard, F-75005 Paris, France - Université Côte d'Azur, CNRS, Inserm, institut de biologie Valrose, Nice, France
| | - Michel Kress
- Sorbonne université, CNRS, institut de biologie Paris-Seine (IBPS), Laboratoire de biologie du développement, 7, quai Saint Bernard, F-75005 Paris, France
| | - Dominique Weil
- Sorbonne université, CNRS, institut de biologie Paris-Seine (IBPS), Laboratoire de biologie du développement, 7, quai Saint Bernard, F-75005 Paris, France
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Min KW, Davila S, Zealy RW, Lloyd LT, Lee IY, Lee R, Roh KH, Jung A, Jemielity J, Choi EJ, Chang JH, Yoon JH. eIF4E phosphorylation by MST1 reduces translation of a subset of mRNAs, but increases lncRNA translation. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2017; 1860:761-772. [PMID: 28487214 DOI: 10.1016/j.bbagrm.2017.05.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Revised: 05/03/2017] [Accepted: 05/05/2017] [Indexed: 10/19/2022]
Abstract
Post-transcriptional gene regulation is an important step in eukaryotic gene expression. The last step to govern production of nascent peptides is during the process of mRNA translation. mRNA translation is controlled by many translation initiation factors that are susceptible to post-translational modifications. Here we report that one of the translation initiation factors, eIF4E, is phosphorylated by Mammalian Ste20-like kinase (MST1). Upon phosphorylation, eIF4E weakly interacts with the 5' CAP to inhibit mRNA translation. Simultaneously, active polyribosome is more associated with long noncoding RNAs (lncRNAs). Moreover, the linc00689-derived micropeptide, STORM (Stress- and TNF-α-activated ORF Micropeptide), is triggered by TNF-α-induced and MST1-mediated eIF4E phosphorylation, which exhibits molecular mimicry of SRP19 and, thus, competes for 7SL RNA. Our findings have uncovered a novel function of MST1 in mRNA and lncRNA translation by direct phosphorylation of eIF4E. This novel signaling pathway will provide new platforms for regulation of mRNA translation via post-translational protein modification.
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Affiliation(s)
- Kyung-Won Min
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC 29425, USA
| | - Sylvia Davila
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC 29425, USA
| | - Richard W Zealy
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC 29425, USA
| | - Lawson T Lloyd
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC 29425, USA
| | - In Young Lee
- Laboratory of Cell Death and Human Diseases, Department of Life Sciences, School of Life Sciences and Biotechnology, Korea University, Seoul, Republic of Korea
| | - Rumi Lee
- Laboratory of Cell Death and Human Diseases, Department of Life Sciences, School of Life Sciences and Biotechnology, Korea University, Seoul, Republic of Korea
| | - Kyung Hye Roh
- Laboratory of Cell Death and Human Diseases, Department of Life Sciences, School of Life Sciences and Biotechnology, Korea University, Seoul, Republic of Korea
| | - Ahjin Jung
- Department of Biology Education, Kyungpook National University, Daegu 41566, Republic of Korea
| | - Jacek Jemielity
- Centre of New Technologies, University of Warsaw, S. Banacha 2c, 02-097 Warsaw, Poland
| | - Eui-Ju Choi
- Laboratory of Cell Death and Human Diseases, Department of Life Sciences, School of Life Sciences and Biotechnology, Korea University, Seoul, Republic of Korea
| | - Jeong Ho Chang
- Department of Biology Education, Kyungpook National University, Daegu 41566, Republic of Korea.
| | - Je-Hyun Yoon
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC 29425, USA; Laboratory of Genetics, National Institute on Aging-Intramural Research Program, NIH, Baltimore, MD 21224, USA.
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Bai Y, Dong Z, Shang Q, Zhao H, Wang L, Guo C, Gao F, Zhang L, Wang Q. Pdcd4 Is Involved in the Formation of Stress Granule in Response to Oxidized Low-Density Lipoprotein or High-Fat Diet. PLoS One 2016; 11:e0159568. [PMID: 27454120 PMCID: PMC4959751 DOI: 10.1371/journal.pone.0159568] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2016] [Accepted: 07/04/2016] [Indexed: 12/26/2022] Open
Abstract
Stress granules (SGs) in response to various stresses have been reported in many diseases. We previously reported the implication of programmed cell death 4 (Pdcd4) in obesity-induced stress responses, but the possible link between Pdcd4 and SGs remains lacking. In this study we showed that oxidized low-density lipoprotein (ox-LDL) or high-fat diet (HFD) induced SG formation in mouse macrophages and liver tissues, and Pdcd4 deficiency in mice remarkably reduced its formation. In response to ox-LDL, either endogenous or ectopic Pdcd4 displayed granule-like expression and co-localized with SG markers including T-cell-restricted intracellular antigen-1, fragile X mental retardation-related protein 1, and eukaryotic initiation factor 4A. Ectopic expression of truncated Pdcd4 that depleted specific RNA-binding motif significantly disrupted the SG formation, suggesting the direct involvement of Pdcd4 in ox-LDL-induced SGs through its RNA-binding activity. Additionally, Pdcd4 deficiency drove AKT activation and suppression of eIF2α phosphorylation, thereby contributing to the resistance to ox-LDL or HFD-induced SG formation. Collectively, our data suggest that Pdcd4 as a crucial regulator in SGs induced by ox-LDL or HFD maybe a potential target for mitigating SG-associated stress responses in obesity and related diseases.
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Affiliation(s)
- Yang Bai
- Department of Immunology, Shandong University School of Medicine, Jinan 250012, Shandong, China
| | - Zhaojing Dong
- Department of Immunology, Shandong University School of Medicine, Jinan 250012, Shandong, China
| | - Qianwen Shang
- Department of Immunology, Shandong University School of Medicine, Jinan 250012, Shandong, China
| | - Hui Zhao
- Department of Immunology, Shandong University School of Medicine, Jinan 250012, Shandong, China
| | - Liyang Wang
- Department of Immunology, Shandong University School of Medicine, Jinan 250012, Shandong, China
| | - Chun Guo
- Department of Immunology, Shandong University School of Medicine, Jinan 250012, Shandong, China
| | - Fei Gao
- The Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Public Health, Qilu Hospital, Shandong University, Jinan 250012, Shandong, China
| | - Lining Zhang
- Department of Immunology, Shandong University School of Medicine, Jinan 250012, Shandong, China
| | - Qun Wang
- Department of Immunology, Shandong University School of Medicine, Jinan 250012, Shandong, China
- * E-mail:
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Podszywalow-Bartnicka P, Wolczyk M, Kusio-Kobialka M, Wolanin K, Skowronek K, Nieborowska-Skorska M, Dasgupta Y, Skorski T, Piwocka K. Downregulation of BRCA1 protein in BCR-ABL1 leukemia cells depends on stress-triggered TIAR-mediated suppression of translation. Cell Cycle 2015; 13:3727-41. [PMID: 25483082 DOI: 10.4161/15384101.2014.965013] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
BRCA1 tumor suppressor regulates crucial cellular processes involved in DNA damage repair and cell cycle control. We showed that expression of BCR-ABL1 correlates with decreased level of BRCA1 protein, which promoted aberrant mitoses and aneuploidy as well as altered DNA damage response. Using polysome profiling and luciferase-BRCA1 3'UTR reporter system here we demonstrate that downregulation of BRCA1 protein in CML is caused by inhibition of BRCA1 mRNA translation, but not by increased protein degradation or reduction of mRNA level and half-life. We investigated 2 mRNA-binding proteins - HuR and TIAR showing specificity to AU-Rich Element (ARE) sites in 3'UTR of mRNA. BCR-ABL1 promoted cytosolic localization of TIAR and HuR, their binding to BRCA1 mRNA and formation of the TIAR-HuR complex. HuR protein positively regulated BRCA1 mRNA stability and translation, conversely TIAR negatively regulated BRCA1 translation and was found localized predominantly in the cytosolic stress granules in CML cells. TIAR-dependent downregulation of BRCA1 protein level was a result of ER stress, which is activated in BCR-ABL1 expressing cells, as we previously shown. Silencing of TIAR in CML cells strongly elevated BRCA1 level. Altogether, we determined that TIAR-mediated repression of BRCA1 mRNA translation is responsible for downregulation of BRCA1 protein level in BCR-ABL1 -positive leukemia cells. This mechanism may contribute to genomic instability and provide justification for targeting PARP1 and/or RAD52 to induce synthetic lethality in "BRCAness" CML and BCR-ABL1 -positive ALL cells.
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Key Words
- ARE, AU-rich element
- ATM, Ataxia telangiectasia mutated kinase
- ATR, Ataxia telangiectasia and Rad3-related kinase
- BCR-ABL
- BRCA1
- BRCA1, Breast cancer type 1 susceptibility
- CML, chronic myeloid leukemia
- DNA damage response
- HuR
- HuR, Hu antigen R (alternative name: ELAV-like protein 1)
- TIAR
- TIAR, TIA1 cytotoxic granule-associated RNA-binding protein-like 1
- UPR, unfolded protein response
- UTR, untranslated region
- cell cycle
- eIF, eukaryotic initiation factor
- mRNA binding protein
- stress response
- synthetic lethality
- translation
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Fritz M, Vanselow J, Sauer N, Lamer S, Goos C, Siegel TN, Subota I, Schlosser A, Carrington M, Kramer S. Novel insights into RNP granules by employing the trypanosome's microtubule skeleton as a molecular sieve. Nucleic Acids Res 2015; 43:8013-32. [PMID: 26187993 PMCID: PMC4652759 DOI: 10.1093/nar/gkv731] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2015] [Accepted: 07/07/2015] [Indexed: 02/07/2023] Open
Abstract
RNP granules are ribonucleoprotein assemblies that regulate the post-transcriptional fate of mRNAs in all eukaryotes. Their exact function remains poorly understood, one reason for this is that RNP granule purification has not yet been achieved. We have exploited a unique feature of trypanosomes to prepare a cellular fraction highly enriched in starvation stress granules. First, granules remain trapped within the cage-like, subpellicular microtubule array of the trypanosome cytoskeleton while soluble proteins are washed away. Second, the microtubules are depolymerized and the granules are released. RNA sequencing combined with single molecule mRNA FISH identified the short and highly abundant mRNAs encoding ribosomal mRNAs as being excluded from granules. By mass spectrometry we have identified 463 stress granule candidate proteins. For 17/49 proteins tested by eYFP tagging we have confirmed the localization to granules, including one phosphatase, one methyltransferase and two proteins with a function in trypanosome life-cycle regulation. The novel method presented here enables the unbiased identification of novel RNP granule components, paving the way towards an understanding of RNP granule function.
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Affiliation(s)
- Melanie Fritz
- Biocenter, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Jens Vanselow
- Rudolf Virchow Center, University of Würzburg, Josef-Schneider-Str. 2, 97080 Würzburg, Germany
| | - Nadja Sauer
- Biocenter, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Stephanie Lamer
- Rudolf Virchow Center, University of Würzburg, Josef-Schneider-Str. 2, 97080 Würzburg, Germany
| | - Carina Goos
- Biocenter, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - T Nicolai Siegel
- Research Center for Infectious Diseases, University of Würzburg, Josef-Schneider-Str. 2, 97080 Würzburg, Germany
| | - Ines Subota
- Biocenter, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Andreas Schlosser
- Rudolf Virchow Center, University of Würzburg, Josef-Schneider-Str. 2, 97080 Würzburg, Germany
| | - Mark Carrington
- Department of Biochemistry, Tennis Court Road, Cambridge CB2 1QW, UK
| | - Susanne Kramer
- Biocenter, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
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Ayache J, Bénard M, Ernoult-Lange M, Minshall N, Standart N, Kress M, Weil D. P-body assembly requires DDX6 repression complexes rather than decay or Ataxin2/2L complexes. Mol Biol Cell 2015; 26:2579-95. [PMID: 25995375 PMCID: PMC4501357 DOI: 10.1091/mbc.e15-03-0136] [Citation(s) in RCA: 112] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Revised: 05/13/2015] [Accepted: 05/13/2015] [Indexed: 01/04/2023] Open
Abstract
P-bodies are cytoplasmic ribonucleoprotein granules involved in posttranscriptional regulation. DDX6 is a key component of their assembly in human cells. This DEAD-box RNA helicase is known to be associated with various complexes, including the decapping complex, the CPEB repression complex, RISC, and the CCR4/NOT complex. To understand which DDX6 complexes are required for P-body assembly, we analyzed the DDX6 interactome using the tandem-affinity purification methodology coupled to mass spectrometry. Three complexes were prominent: the decapping complex, a CPEB-like complex, and an Ataxin2/Ataxin2L complex. The exon junction complex was also found, suggesting DDX6 binding to newly exported mRNAs. Finally, some DDX6 was associated with polysomes, as previously reported in yeast. Despite its high enrichment in P-bodies, most DDX6 is localized out of P-bodies. Of the three complexes, only the decapping and CPEB-like complexes were recruited into P-bodies. Investigation of P-body assembly in various conditions allowed us to distinguish required proteins from those that are dispensable or participate only in specific conditions. Three proteins were required in all tested conditions: DDX6, 4E-T, and LSM14A. These results reveal the variety of pathways of P-body assembly, which all nevertheless share three key factors connecting P-body assembly to repression.
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Affiliation(s)
- Jessica Ayache
- UPMC Université de Paris 06, Institut de Biologie Paris-Seine, CNRS UMR-7622, F-75005 Paris, France
| | - Marianne Bénard
- UPMC Université de Paris 06, Institut de Biologie Paris-Seine, CNRS UMR-7622, F-75005 Paris, France
| | - Michèle Ernoult-Lange
- UPMC Université de Paris 06, Institut de Biologie Paris-Seine, CNRS UMR-7622, F-75005 Paris, France
| | - Nicola Minshall
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, United Kingdom
| | - Nancy Standart
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, United Kingdom
| | - Michel Kress
- UPMC Université de Paris 06, Institut de Biologie Paris-Seine, CNRS UMR-7622, F-75005 Paris, France
| | - Dominique Weil
- UPMC Université de Paris 06, Institut de Biologie Paris-Seine, CNRS UMR-7622, F-75005 Paris, France
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Qiu LQ, Abey S, Harris S, Shah R, Gerrish KE, Blackshear PJ. Global analysis of posttranscriptional gene expression in response to sodium arsenite. ENVIRONMENTAL HEALTH PERSPECTIVES 2015; 123:324-30. [PMID: 25493608 PMCID: PMC4383576 DOI: 10.1289/ehp.1408626] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Accepted: 11/19/2014] [Indexed: 05/26/2023]
Abstract
BACKGROUND Inorganic arsenic species are potent environmental toxins and causes of numerous health problems. Most studies have assumed that arsenic-induced changes in mRNA levels result from effects on gene transcription. OBJECTIVES We evaluated the prevalence of changes in mRNA stability in response to sodium arsenite in human fibroblasts. METHODS We used microarray analyses to determine changes in steady-state mRNA levels and mRNA decay rates following 24-hr exposure to noncytotoxic concentrations of sodium arsenite, and we confirmed some of these changes using real-time reverse-transcription polymerase chain reaction (RT-PCR). RESULTS In arsenite-exposed cells, 186 probe set-identified transcripts were significantly increased and 167 were significantly decreased. When decay rates were analyzed after actinomycin D treatment, only 4,992 (9.1%) of probe set-identified transcripts decayed by > 25% after 4 hr. Of these, 70 were among the 353 whose steady-state levels were altered by arsenite, and of these, only 4 exhibited significantly different decay rates between arsenite and control treatment. Real-time RT-PCR confirmed a major, significant arsenite-induced stabilization of the mRNA encoding δ aminolevulinate synthase 1 (ALAS1), the rate-limiting enzyme in heme biosynthesis. This change presumably accounted for at least part of the 2.7-fold increase in steady-state ALAS1 mRNA levels seen after arsenite treatment. This could reflect decreases in cellular heme caused by the massive induction by arsenite of heme oxygenase mRNA (HMOX1; 68-fold increase), the rate-limiting enzyme in heme catabolism. CONCLUSIONS We conclude that arsenite modification of mRNA stability is relatively uncommon, but in some instances can result in significant changes in gene expression.
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Affiliation(s)
- Lian-Qun Qiu
- Laboratory of Signal Transduction, National Institute of Environmental Health Sciences (NIEHS), National Institutes of Health (NIH), Department of Health and Human Services (DHHS), Research Triangle Park, North Carolina, USA
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10
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Wang JT, Smith J, Chen BC, Schmidt H, Rasoloson D, Paix A, Lambrus BG, Calidas D, Betzig E, Seydoux G. Regulation of RNA granule dynamics by phosphorylation of serine-rich, intrinsically disordered proteins in C. elegans. eLife 2014; 3:e04591. [PMID: 25535836 PMCID: PMC4296509 DOI: 10.7554/elife.04591] [Citation(s) in RCA: 255] [Impact Index Per Article: 25.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Accepted: 12/18/2014] [Indexed: 12/19/2022] Open
Abstract
RNA granules have been likened to liquid droplets whose dynamics depend on the controlled dissolution and condensation of internal components. The molecules and reactions that drive these dynamics in vivo are not well understood. In this study, we present evidence that a group of intrinsically disordered, serine-rich proteins regulate the dynamics of P granules in C. elegans embryos. The MEG (maternal-effect germline defective) proteins are germ plasm components that are required redundantly for fertility. We demonstrate that MEG-1 and MEG-3 are substrates of the kinase MBK-2/DYRK and the phosphatase PP2A(PPTR-½). Phosphorylation of the MEGs promotes granule disassembly and dephosphorylation promotes granule assembly. Using lattice light sheet microscopy on live embryos, we show that GFP-tagged MEG-3 localizes to a dynamic domain that surrounds and penetrates each granule. We conclude that, despite their liquid-like behavior, P granules are non-homogeneous structures whose assembly in embryos is regulated by phosphorylation.
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Affiliation(s)
- Jennifer T Wang
- Department of Molecular Biology and Genetics, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, United States
| | - Jarrett Smith
- Department of Molecular Biology and Genetics, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, United States
| | - Bi-Chang Chen
- Research Center for Applied Sciences, Academica Sinica, Taipei, Taiwan
| | - Helen Schmidt
- Department of Molecular Biology and Genetics, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, United States
| | - Dominique Rasoloson
- Department of Molecular Biology and Genetics, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, United States
| | - Alexandre Paix
- Department of Molecular Biology and Genetics, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, United States
| | - Bramwell G Lambrus
- Department of Molecular Biology and Genetics, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, United States
| | - Deepika Calidas
- Department of Molecular Biology and Genetics, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, United States
| | - Eric Betzig
- Janelia Farm Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Geraldine Seydoux
- Department of Molecular Biology and Genetics, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, United States
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