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Shlezinger N, Irmer H, Dhingra S, Beattie SR, Cramer RA, Braus GH, Sharon A, Hohl TM. Response to Comment on "Sterilizing immunity in the lung relies on targeting fungal apoptosis-like programmed cell death". Science 2018; 360:360/6395/eaas9457. [PMID: 29930111 DOI: 10.1126/science.aas9457] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Accepted: 05/10/2018] [Indexed: 12/22/2022]
Abstract
Aouacheria et al question the interpretation of contemporary assays to monitor programmed cell death with apoptosis-like features (A-PCD) in Aspergillus fumigatus Although our study focuses on fungal A-PCD for host immune surveillance and infectious outcomes, the experimental approach incorporates multiple independent A-PCD markers and genetic manipulations based on fungal rather than mammalian orthologs to circumvent the limitations associated with any single approach.
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Affiliation(s)
- Neta Shlezinger
- Infectious Disease Service, Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY 10075, USA
| | - Henriette Irmer
- Department of Molecular Microbiology and Genetics, Institute for Microbiology and Genetics, and Göttingen Center for Molecular Biosciences, University of Göttingen, D-37077 Göttingen, Germany
| | - Sourabh Dhingra
- Department of Microbiology and Immunology, Geisel School of Medicine, Dartmouth College, Hanover, NH 03755, USA
| | - Sarah R Beattie
- Department of Microbiology and Immunology, Geisel School of Medicine, Dartmouth College, Hanover, NH 03755, USA
| | - Robert A Cramer
- Department of Microbiology and Immunology, Geisel School of Medicine, Dartmouth College, Hanover, NH 03755, USA
| | - Gerhard H Braus
- Department of Molecular Microbiology and Genetics, Institute for Microbiology and Genetics, and Göttingen Center for Molecular Biosciences, University of Göttingen, D-37077 Göttingen, Germany
| | - Amir Sharon
- Department of Molecular Biology and Ecology of Plants, Tel Aviv University, Tel Aviv 69978, Israel.
| | - Tobias M Hohl
- Infectious Disease Service, Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY 10075, USA. .,Immunology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, NY 10075, USA
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Shlezinger N, Irmer H, Dhingra S, Beattie SR, Cramer RA, Braus GH, Sharon A, Hohl TM. Sterilizing immunity in the lung relies on targeting fungal apoptosis-like programmed cell death. Science 2018; 357:1037-1041. [PMID: 28883073 DOI: 10.1126/science.aan0365] [Citation(s) in RCA: 69] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Accepted: 06/22/2017] [Indexed: 01/24/2023]
Abstract
Humans inhale mold conidia daily and typically experience lifelong asymptomatic clearance. Conidial germination into tissue-invasive hyphae can occur in individuals with defects in myeloid function, although the mechanism of myeloid cell-mediated immune surveillance remains unclear. By monitoring fungal physiology in vivo, we demonstrate that lung neutrophils trigger programmed cell death with apoptosis-like features in Aspergillus fumigatus conidia, the most prevalent human mold pathogen. An antiapoptotic protein, AfBIR1, opposes this process by inhibiting fungal caspase activation and DNA fragmentation in the murine lung. Genetic and pharmacologic studies indicate that AfBIR1 expression and activity underlie conidial susceptibility to NADPH (reduced form of nicotinamide adenine dinucleotide phosphate) oxidase-dependent killing and, in turn, host susceptibility to invasive aspergillosis. Immune surveillance exploits a fungal apoptosis-like programmed cell death pathway to maintain sterilizing immunity in the lung.
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Affiliation(s)
- Neta Shlezinger
- Infectious Disease Service, Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Henriette Irmer
- Department of Molecular Microbiology and Genetics, Institute for Microbiology and Genetics and Göttingen Center for Molecular Biosciences, University of Göttingen, D-37077 Göttingen, Germany
| | - Sourabh Dhingra
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA
| | - Sarah R Beattie
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA
| | - Robert A Cramer
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA
| | - Gerhard H Braus
- Department of Molecular Microbiology and Genetics, Institute for Microbiology and Genetics and Göttingen Center for Molecular Biosciences, University of Göttingen, D-37077 Göttingen, Germany
| | - Amir Sharon
- Department of Molecular Biology and Ecology of Plants, Tel Aviv University, Tel Aviv 69978, Israel.
| | - Tobias M Hohl
- Infectious Disease Service, Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA. .,Immunology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
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Irmer H, Tarazona S, Sasse C, Olbermann P, Loeffler J, Krappmann S, Conesa A, Braus GH. RNAseq analysis of Aspergillus fumigatus in blood reveals a just wait and see resting stage behavior. BMC Genomics 2015; 16:640. [PMID: 26311470 PMCID: PMC4551469 DOI: 10.1186/s12864-015-1853-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Accepted: 08/17/2015] [Indexed: 12/20/2022] Open
Abstract
Background Invasive aspergillosis is started after germination of Aspergillus fumigatus conidia that are inhaled by susceptible individuals. Fungal hyphae can grow in the lung through the epithelial tissue and disseminate hematogenously to invade into other organs. Low fungaemia indicates that fungal elements do not reside in the bloodstream for long. Results We analyzed whether blood represents a hostile environment to which the physiology of A. fumigatus has to adapt. An in vitro model of A. fumigatus infection was established by incubating mycelium in blood. Our model allowed to discern the changes of the gene expression profile of A. fumigatus at various stages of the infection. The majority of described virulence factors that are connected to pulmonary infections appeared not to be activated during the blood phase. Three active processes were identified that presumably help the fungus to survive the blood environment in an advanced phase of the infection: iron homeostasis, secondary metabolism, and the formation of detoxifying enzymes. Conclusions We propose that A. fumigatus is hardly able to propagate in blood. After an early stage of sensing the environment, virtually all uptake mechanisms and energy-consuming metabolic pathways are shut-down. The fungus appears to adapt by trans-differentiation into a resting mycelial stage. This might reflect the harsh conditions in blood where A. fumigatus cannot take up sufficient nutrients to establish self-defense mechanisms combined with significant growth. Electronic supplementary material The online version of this article (doi10.1186/s12864-015-1853-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Henriette Irmer
- Institut für Mikrobiologie und Genetik, Georg-August-Universität Göttingen, Grisebachstraße 8, D-37077, Göttingen, Germany.
| | - Sonia Tarazona
- Genomics of Gene Expression Lab, Prince Felipe Research Center, Av. Eduardo Primo Yufera 3, 46012, Valencia, Spain.
| | - Christoph Sasse
- Institut für Mikrobiologie und Genetik, Georg-August-Universität Göttingen, Grisebachstraße 8, D-37077, Göttingen, Germany.
| | - Patrick Olbermann
- Research Center for Infectious Diseases, Julius-Maximilians University Würzburg, Würzburg, Germany.
| | - Jürgen Loeffler
- Laboratory WÜ4i, Medical Clinic and Policlinic II, University Clinic Würzburg, Würzburg, Germany.
| | - Sven Krappmann
- Research Center for Infectious Diseases, Julius-Maximilians University Würzburg, Würzburg, Germany. .,Mikrobiologisches Institut - Klinische Mikrobiologie, Immunologie und Hygiene, Universitätsklinik Erlangen and Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany.
| | - Ana Conesa
- Genomics of Gene Expression Lab, Prince Felipe Research Center, Av. Eduardo Primo Yufera 3, 46012, Valencia, Spain. .,Department of Microbiology and Cell Science, Institute for Food and Agricultura Sciences, University of Florida at Gainesville, Gainesville, FL, USA.
| | - Gerhard H Braus
- Institut für Mikrobiologie und Genetik, Georg-August-Universität Göttingen, Grisebachstraße 8, D-37077, Göttingen, Germany.
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von Bernstorff W, Irmer H, Menges P, Peters S, Heidecke CD, Busemann A. [Surgical History Taking and Clinical Examination: Establishing a Standardised System by Means of a Nation-Wide Academic Teaching Project]. Zentralbl Chir 2014; 142:39-45. [PMID: 25393734 DOI: 10.1055/s-0034-1383078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Background: History taking and systematic clinical examination are central techniques of physicians. Medicine in general and surgery in particular frequently require immediate decisions and start of therapies. So far, a standardised surgical system for history taking and clinical examination in teaching has been lacking at our faculty. A consensus of all medical faculties on a standardised system could be a tool to improve the medical teaching and education at our teaching institutions. Methods: The established Anglo-Saxonian system of history taking and clinical examination was adapted to our own clinical needs. Thereafter, this system was sent out to all chairmen of general and visceral surgery departments in German University Hospitals asking for evaluation and improvements. We adapted the system according to the chairmen's comments and suggestions. Since winter semester 2011 this system has been integrated into the clinical course of history taking and examination. It is compulsory for all 5th semester students (first clinical year/graduate course) at the Universitätsmedizin Greifswald. In addition, a video was produced demonstrating all major techniques of clinical examination. This video is available for all students on a password blocked site of the World Wide Web. Results: Altogether, 89 % of all contacted chairmen returned their comments and suggestions for improvements. After implementation of the new system, positive evaluations of students increased significantly from 63.5 to 77.0 % in general and abdominal surgery (p < 0.0001) and from 76.4 to 83.5 % in vascular and thoracic surgery (p < 0.0001). Conclusions: The presented system is a standardised tool of history taking and clinical examination applicable for students as well as qualified surgeons in daily routine work. It has been approved by the majority of the departments of surgery of all German university hospitals. Furthermore, it can be applied by other medical specialties, in particular, internal medicine. Furthermore, the standardisation of history taking and clinical examination can contribute to improve patients' safety as well as medical documentation. Also, the standardisation will be a sound basis for expert medical opinions in legal actions. Finally, it has improved the value of medical education at our medical faculty and could form the basis for the development of national medical standards.
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Affiliation(s)
- W von Bernstorff
- Abteilung für Allgemeine Chirurgie, Viszeral-, Thorax- und Gefäßchirurgie, Klinik und Poliklinik für Chirurgie, Universitätsmedizin Greifswald, Deutschland
| | - H Irmer
- Abteilung für Allgemeine Chirurgie, Viszeral-, Thorax- und Gefäßchirurgie, Klinik und Poliklinik für Chirurgie, Universitätsmedizin Greifswald, Deutschland
| | - P Menges
- Abteilung für Allgemeine Chirurgie, Viszeral-, Thorax- und Gefäßchirurgie, Klinik und Poliklinik für Chirurgie, Universitätsmedizin Greifswald, Deutschland
| | - S Peters
- Abteilung für Allgemeine Chirurgie, Viszeral-, Thorax- und Gefäßchirurgie, Klinik und Poliklinik für Chirurgie, Universitätsmedizin Greifswald, Deutschland
| | - C-D Heidecke
- Abteilung für Allgemeine Chirurgie, Viszeral-, Thorax- und Gefäßchirurgie, Klinik und Poliklinik für Chirurgie, Universitätsmedizin Greifswald, Deutschland
| | - A Busemann
- Abteilung für Allgemeine Chirurgie, Viszeral-, Thorax- und Gefäßchirurgie, Klinik und Poliklinik für Chirurgie, Universitätsmedizin Greifswald, Deutschland
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von Zeska Kress MR, Harting R, Bayram Ö, Christmann M, Irmer H, Valerius O, Schinke J, Goldman GH, Braus GH. The COP9 signalosome counteracts the accumulation of cullin SCF ubiquitin E3 RING ligases during fungal development. Mol Microbiol 2012; 83:1162-77. [PMID: 22329854 DOI: 10.1111/j.1365-2958.2012.07999.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Defects in the COP9 signalosome (CSN) impair multicellular development, including embryonic plant or animal death or a block in sexual development of the fungus Aspergillus nidulans. CSN deneddylates cullin-RING ligases (CRLs), which are activated by covalent linkage to ubiquitin-like NEDD8. Deneddylation allows CRL disassembly for subsequent reassembly. An attractive hypothesis is a consecutive order of CRLs for development, which demands repeated cycles of neddylation and deneddylation for reassembling CRLs. Interruption of these cycles could explain developmental blocks caused by csn mutations. This predicts an accumulation of neddylated CRLs exhibiting developmental functions when CSN is dysfunctional. We tested this hypothesis in A. nidulans, which tolerates reduced levels of neddylation for growth. We show that only genes for CRL subunits or neddylation are essential, whereas CSN is primarily required for development. We used functional tagged NEDD8, recruiting all three fungal cullins. Cullins are associated with the CSN1/CsnA subunit when deneddylation is defective. Two CRLs were identified which are specifically involved in differentiation and accumulate during the developmental block. This suggests that an active CSN complex is required to counteract the accumulation of specific CRLs during development.
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Affiliation(s)
- Marcia Regina von Zeska Kress
- Institut für Mikrobiologie und Genetik, Georg-August-Universität Göttingen, Grisebachstrasse 8, D-37077 Göttingen, Germany
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Šarić M, Irmer H, Eckert D, Bär AK, Bruchhaus I, Scholze H. The cysteine protease inhibitors EhICP1 and EhICP2 perform different tasks in the regulation of endogenous protease activity in trophozoites of Entamoeba histolytica. Protist 2011; 163:116-28. [PMID: 21440496 DOI: 10.1016/j.protis.2011.01.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2010] [Accepted: 01/24/2011] [Indexed: 11/26/2022]
Abstract
Trophozoites of E. histolytica are equipped with two chagasin-like cysteine protease inhibitors, EhICP1 and EhICP2, also known as amoebiasin 1 and 2. Expression studies using E. invadens as model organism showed that corresponding mRNAs were detectable in both life stages of the parasite, cyst and trophozoite state. Unlike EhICP1 known to act in the cytosol, EhICP2 co-localized with cysteine protease EhCP-A1 in lysosome-like vesicles, as demonstrated by immunofluorescence microscopy. Silencing or overexpressing of the two inhibitors did not show any effect on morphology and viability of the trophozoites. Overexpression of the EhICPs, however, although dramatically dampening the proteolytic activity of cell extracts from the corresponding cell lines, did not influence expression rate or localization of the major amoebic cysteine proteases as well as phagocytosis and digestion of erythrocytes. Activity gels of cell extracts from strains overexpressing ehicp1 showed a drastically reduced activity of EhCP-A1 suggesting a high affinity of EhICP1 towards this protease. From these data, we propose that EhCP-A1 accidentally released into the cytosol is the main target of EhICP1, whereas EhICP2, beside its role in house-keeping processes, may control the proteolytic processing of other hydrolases or fulfils other tasks different from protease inhibition.
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Affiliation(s)
- Mirela Šarić
- Faculty of Biology, Department of Biochemistry, University of Osnabrueck, Barbarastr. 13, D-49069 Osnabrueck, Germany
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Irmer H, Tillack M, Biller L, Handal G, Leippe M, Roeder T, Tannich E, Bruchhaus I. Major cysteine peptidases ofEntamoeba histolyticaare required for aggregation and digestion of erythrocytes but are dispensable for phagocytosis and cytopathogenicity. Mol Microbiol 2009; 72:658-67. [DOI: 10.1111/j.1365-2958.2009.06672.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Li CH, Irmer H, Gudjonsdottir-Planck D, Freese S, Salm H, Haile S, Estévez AM, Clayton C. Roles of a Trypanosoma brucei 5'->3' exoribonuclease homolog in mRNA degradation. RNA 2006; 12:2171-86. [PMID: 17077271 PMCID: PMC1664730 DOI: 10.1261/rna.291506] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2006] [Accepted: 09/21/2006] [Indexed: 05/09/2023]
Abstract
The genome of the kinetoplastid parasite Trypanosoma brucei encodes four homologs of the Saccharomyces cerevisiae 5'-->3' exoribonucleases Xrn1p and Xrn2p/Rat1p, XRNA, XRNB, XRNC, and XRND. In S. cerevisiae, Xrn1p is a cytosolic enzyme involved in degradation of mRNA, whereas Xrn2p is involved in RNA processing in the nucleus. Trypanosome XRND was found in the nucleus, XRNB and XRNC were found in the cytoplasm, and XRNA appeared to be in both compartments. XRND and XRNA were essential for parasite growth. Depletion of XRNA increased the abundances of highly unstable developmentally regulated mRNAs, perhaps by delaying a deadenylation-independent decay pathway. Degradation of more stable or unregulated mRNAs was not affected by XRNA depletion although a slight decrease in average poly(A) tail length was observed. We conclude that in trypanosomes 5'-->3' exonuclease activity is important in degradation of highly unstable, regulated mRNAs, but that for other mRNAs another step is more important in determining the decay rate.
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Affiliation(s)
- Chi-Ho Li
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), D-69120 Heidelberg, Germany
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Arhin GK, Shen S, Irmer H, Ullu E, Tschudi C. Role of a 300-kilodalton nuclear complex in the maturation of Trypanosoma brucei initiator methionyl-tRNA. Eukaryot Cell 2005; 3:893-9. [PMID: 15302822 PMCID: PMC500872 DOI: 10.1128/ec.3.4.893-899.2004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
tRNAs are transcribed as precursors containing 5' leader and 3' extensions that are removed by a series of posttranscriptional processing reactions to yield functional mature tRNAs. Here, we examined the maturation pathway of tRNA(Met) in Trypanosoma brucei, an early divergent unicellular eukaryote. We identified an approximately 300-kDa complex located in the nucleus of T. brucei that is required for trimming the 5' leader of initiator tRNA(Met) precursors. One of the subunits of the complex (T. brucei MT40 [TbMT40]) is a putative methyltransferase and a homolog of Saccharomyces cerevisiae Gcd14, which is essential for 1-methyladenosine modification in tRNAs. Down-regulation of TbMT40 by RNA interference resulted in the accumulation of precursor initiator tRNA(Met) containing 5' extensions but processed 3' ends. In addition, immunoprecipitations with anti-La antibodies revealed initiator tRNA(Met) molecules with 5' and 3' extensions in TbMT40-silenced cells, albeit at a much lower level. Interestingly, silencing of TbMT40, as well as of TbMT53, a second subunit of the complex, led to an increase in the levels of mature elongator tRNA(Met). Taken together, our data provide a glance at the maturation of tRNAs in parasitic protozoa and suggest that at least for initiator tRNA(Met), 3' trimming precedes 5' processing.
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Affiliation(s)
- George K Arhin
- Department of Epidemiology and Public Health, Yale University Medical School, 295 Congress Avenue, New Haven, CT 06536-0812, USA
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Quijada L, Guerra-Giraldez C, Drozdz M, Hartmann C, Irmer H, Ben-Dov C, Cristodero M, Ding M, Clayton C. Expression of the human RNA-binding protein HuR in Trypanosoma brucei increases the abundance of mRNAs containing AU-rich regulatory elements. Nucleic Acids Res 2002; 30:4414-24. [PMID: 12384588 PMCID: PMC137141 DOI: 10.1093/nar/gkf577] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The salivarian trypanosome Trypanosoma brucei infects mammals and is transmitted by tsetse flies. The mammalian 'bloodstream form' trypanosome has a variant surface glycoprotein coat and relies on glycolysis while the procyclic form from tsetse flies has EP protein on the surface and has a more developed mitochondrion. We show here that the mRNA for the procyclic-specific cytosolic phosphoglycerate kinase PGKB, like that for EP proteins, contains a regulatory AU-rich element (ARE) that destabilises the mRNA in bloodstream forms. The human HuR protein binds to, and stabilises, mammalian mRNAs containing AREs. Expression of HuR in bloodstream-form trypanosomes resulted in growth arrest and in stabilisation of the EP, PGKB and pyruvate, phosphate dikinase mRNAs, while three bloodstream-specific mRNAs were reduced in abundance. The synthesis and abundance of unregulated mRNAs and proteins were unaffected. Our results suggest that regulation of mRNA stability by AREs arose early in eukaryotic evolution.
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Affiliation(s)
- Luis Quijada
- ZMBH, Im Neuenheimer Feld 282, D-69120 Heidelberg, Germany
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Irmer H, Clayton C. Degradation of the unstable EP1 mRNA in Trypanosoma brucei involves initial destruction of the 3'-untranslated region. Nucleic Acids Res 2001; 29:4707-15. [PMID: 11713321 PMCID: PMC92565 DOI: 10.1093/nar/29.22.4707] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Kinetoplastid protozoa regulate their gene expression primarily through control of mRNA degradation and translation. We describe here the degradation of three reporter mRNAs in Trypanosoma brucei. One mRNA had the 3'-untranslated region (3'-UTR) from the developmentally regulated EP1 mRNA, which is abundant in the procyclic (tsetse fly) form of the parasite but is almost undetectable in the bloodstream form. This untranslated region includes a 26 nt U-rich sequence that causes extreme RNA instability in the bloodstream form. The two other RNAs, which are not developmentally regulated, had either the actin 3'-UTR, or a version of the EP1 sequence lacking the 26 nt bloodstream-form instability element. All RNAs had poly(A) tails approximately 200 nt long, in both bloodstream and procyclic forms. Degradation of the two constitutively expressed mRNAs involved deadenylation and degradation by both 5'-->3' and 3'-->5' exonucleases. In contrast, in bloodstream forms, the 3'-end of the RNA bearing the bloodstream-form instability element disappeared very rapidly after transcription inhibition and partially deadenylated intermediates were not seen. The instability element may cause extremely rapid deadenylation, or it may be targeted by an endonuclease.
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Affiliation(s)
- H Irmer
- Zentrum für Molekulare Biologie Heidelberg, Im Neuenheimer Feld 282, D-69120 Heidelberg, Germany
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Abstract
The homo-oligomeric Hip protein cooperates with the 70-kDa heat shock cognate Hsc70 in the folding of newly synthesized polypeptide chains and in the conformational regulation of signaling molecules known to interact with Hsc70 and Hsp90. In order to further assess the role of Hip during protein biogenesis, a structure-function analysis of the Hip protein was initiated. By employing the yeast two-hybrid system, the Hsc70-binding site of Hip was mapped to a domain comprising multiple tetratricopeptide repeats and flanking charged alpha-helices. Affinity chromatography confirmed direct interaction of isolated Hip fragments and protein fusions bearing this region with the ATPase domain of Hsc70 in an ATP- and salt-dependent manner. Contact of Hip with the ATPase domain appears to be mediated primarily by the positively charged alpha-helix following the tetratricopeptide repeats. Furthermore, a domain required for homo-oligomerization was identified at the extreme amino terminus of Hip.
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Affiliation(s)
- H Irmer
- Zentrum für Molekulare Biologie, Universität Heidelberg, Im Neuenheimer Feld 282, D-69120 Heidelberg, Germany
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Irmer H. [Prevention of water pollution of the Rhine river--from the thiodan accident until today]. Schriftenr Ver Wasser Boden Lufthyg 1995; 95:97-110. [PMID: 7777820] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Affiliation(s)
- H Irmer
- Landesumweltamt Nordrhein-Westfalen
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