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Kramer S, Karolak NK, Odenwald J, Gabiatti B, Castañeda Londoño P, Zavřelová A, Freire E, Almeida K, Braune S, Moreira C, Eder A, Goos C, Field M, Carrington M, Holetz F, Górna M, Zoltner M. A unique mRNA decapping complex in trypanosomes. Nucleic Acids Res 2023; 51:7520-7540. [PMID: 37309887 PMCID: PMC10415143 DOI: 10.1093/nar/gkad497] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Revised: 05/18/2023] [Accepted: 06/06/2023] [Indexed: 06/14/2023] Open
Abstract
Removal of the mRNA 5' cap primes transcripts for degradation and is central for regulating gene expression in eukaryotes. The canonical decapping enzyme Dcp2 is stringently controlled by assembly into a dynamic multi-protein complex together with the 5'-3'exoribonuclease Xrn1. Kinetoplastida lack Dcp2 orthologues but instead rely on the ApaH-like phosphatase ALPH1 for decapping. ALPH1 is composed of a catalytic domain flanked by C- and N-terminal extensions. We show that T. brucei ALPH1 is dimeric in vitro and functions within a complex composed of the trypanosome Xrn1 ortholog XRNA and four proteins unique to Kinetoplastida, including two RNA-binding proteins and a CMGC-family protein kinase. All ALPH1-associated proteins share a unique and dynamic localization to a structure at the posterior pole of the cell, anterior to the microtubule plus ends. XRNA affinity capture in T. cruzi recapitulates this interaction network. The ALPH1 N-terminus is not required for viability in culture, but essential for posterior pole localization. The C-terminus, in contrast, is required for localization to all RNA granule types, as well as for dimerization and interactions with XRNA and the CMGC kinase, suggesting possible regulatory mechanisms. Most significantly, the trypanosome decapping complex has a unique composition, differentiating the process from opisthokonts.
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Affiliation(s)
| | - Natalia Katarzyna Karolak
- Biological and Chemical Research Centre, Department of Chemistry, University of Warsaw, Warsaw, Poland
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland
| | | | - Bernardo Gabiatti
- Biocenter, University of Würzburg, Würzburg, Germany
- Carlos Chagas Institute (ICC), FIOCRUZ/PR, Curitiba, Brazil
| | | | - Anna Zavřelová
- Department of Parasitology, Faculty of Science, Charles University in Prague, Biocev, Vestec, Czech Republic
| | | | | | - Silke Braune
- Biocenter, University of Würzburg, Würzburg, Germany
| | - Claudia Moreira
- Biocenter, University of Würzburg, Würzburg, Germany
- Carlos Chagas Institute (ICC), FIOCRUZ/PR, Curitiba, Brazil
| | - Amelie Eder
- Biocenter, University of Würzburg, Würzburg, Germany
| | - Carina Goos
- Biocenter, University of Würzburg, Würzburg, Germany
| | - Mark Field
- School of Life Sciences, University of Dundee, Dundee, UK
- Biology Centre, Czech Academy of Sciences, Institute of Parasitology, České Budějovice, Czech Republic
| | - Mark Carrington
- Department of Biochemistry, University of Cambridge, Cambridge, UK
| | - Fabiola Holetz
- Carlos Chagas Institute (ICC), FIOCRUZ/PR, Curitiba, Brazil
| | - Maria Wiktoria Górna
- Biological and Chemical Research Centre, Department of Chemistry, University of Warsaw, Warsaw, Poland
| | - Martin Zoltner
- Department of Parasitology, Faculty of Science, Charles University in Prague, Biocev, Vestec, Czech Republic
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Ren J, Zhang Y, Guo W, Feng K, Yuan Y, Huang T, Cai YD. Identification of Genes Associated with the Impairment of Olfactory and Gustatory Functions in COVID-19 via Machine-Learning Methods. Life (Basel) 2023; 13:798. [PMID: 36983953 PMCID: PMC10051382 DOI: 10.3390/life13030798] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Revised: 03/10/2023] [Accepted: 03/13/2023] [Indexed: 03/17/2023] Open
Abstract
The coronavirus disease 2019 (COVID-19), as a severe respiratory disease, affects many parts of the body, and approximately 20-85% of patients exhibit functional impairment of the senses of smell and taste, some of whom even experience the permanent loss of these senses. These symptoms are not life-threatening but severely affect patients' quality of life and increase the risk of depression and anxiety. The pathological mechanisms of these symptoms have not been fully identified. In the current study, we aimed to identify the important biomarkers at the expression level associated with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection-mediated loss of taste or olfactory ability, and we have suggested the potential pathogenetic mechanisms of COVID-19 complications. We designed a machine-learning-based approach to analyze the transcriptome of 577 COVID-19 patient samples, including 84 COVID-19 samples with a decreased ability to taste or smell and 493 COVID-19 samples without impairment. Each sample was represented by 58,929 gene expression levels. The features were analyzed and sorted by three feature selection methods (least absolute shrinkage and selection operator, light gradient boosting machine, and Monte Carlo feature selection). The optimal feature sets were obtained through incremental feature selection using two classification algorithms: decision tree (DT) and random forest (RF). The top genes identified by these multiple methods (H3-5, NUDT5, and AOC1) are involved in olfactory and gustatory impairments. Meanwhile, a high-performance RF classifier was developed in this study, and three sets of quantitative rules that describe the impairment of olfactory and gustatory functions were obtained based on the optimal DT classifiers. In summary, this study provides a new computation analysis and suggests the latent biomarkers (genes and rules) for predicting olfactory and gustatory impairment caused by COVID-19 complications.
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Affiliation(s)
- Jingxin Ren
- School of Life Sciences, Shanghai University, Shanghai 200444, China
| | - Yuhang Zhang
- Channing Division of Network Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Wei Guo
- Key Laboratory of Stem Cell Biology, Shanghai Jiao Tong University School of Medicine (SJTUSM) & Shanghai Institutes for Biological Sciences (SIBS), Chinese Academy of Sciences (CAS), Shanghai 200030, China
| | - Kaiyan Feng
- Department of Computer Science, Guangdong AIB Polytechnic College, Guangzhou 510507, China
| | - Ye Yuan
- Institute of Image Processing and Pattern Recognition, Shanghai Jiao Tong University, and Key Laboratory of System Control and Information Processing, Ministry of Education of China, Shanghai 200240, China
| | - Tao Huang
- Bio-Med Big Data Center, CAS Key Laboratory of Computational Biology, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, China
- CAS Key Laboratory of Tissue Microenvironment and Tumor, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Yu-Dong Cai
- School of Life Sciences, Shanghai University, Shanghai 200444, China
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Abstract
Abstract
In Trypanosoma brucei and related Kinetoplastids, regulation of gene expression occurs mostly post-transcriptionally, and RNA-binding proteins play a critical role in the regulation of mRNA and protein abundance. Trypanosoma brucei ZC3H28 is a 114 KDa cytoplasmic mRNA-binding protein with a single C(x)7C(x)5C(x)sH zinc finger at the C-terminus and numerous proline-, histidine- or glutamine-rich regions. ZC3H28 is essential for normal bloodstream-form trypanosome growth, and when tethered to a reporter mRNA, ZC3H28 increased reporter mRNA and protein levels. Purification of N-terminally tagged ZC3H28 followed by mass spectrometry showed enrichment of ribosomal proteins, various RNA-binding proteins including both poly(A) binding proteins, the translation initiation complex EIF4E4/EIF4G3, and the activator MKT1. Tagged ZC3H28 was preferentially associated with long RNAs that have low complexity sequences in their 3′-untranslated regions; their coding regions also have low ribosome densities. In agreement with the tethering results, after ZC3H28 depletion, the levels of a significant proportion of its bound mRNAs decreased. We suggest that ZC3H28 is implicated in the stabilization of long mRNAs that are poorly translated.
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Abstract
Trypanosoma brucei is unusually reliant on mRNA-binding proteins to control mRNA fate, because its protein-coding genes lack individual promoters. We here focus on three trypanosome RNA-binding proteins. ZC3H22 is specific to Tsetse fly forms, RBP9 is preferentially expressed in bloodstream forms; and DRBD7 is constitutively expressed. Depletion of RBP9 or DRBD7 did not affect bloodstream-form trypanosome growth. ZC3H22 depletion from procyclic forms caused cell clumping, decreased expression of genes required for cell growth and proliferation, and increased expression of some epimastigote markers. Apart from decreases in mRNAs encoding enzymes of glucose metabolism, levels of most ZC3H22-bound transcripts were unaffected by ZC3H22 depletion. We compared ZC3H22, RBP9 and DRBD7 RNA binding with that of 16 other RNA-binding proteins. ZC3H22, PUF3 and ERBP1 show a preference for ribosomal protein mRNAs. RBP9 preferentially binds mRNAs that are more abundant in bloodstream forms than in procyclic forms. RBP9, ZC3H5, ZC3H30 and DRBD7 prefer mRNAs with long coding regions; UBP1-associated mRNAs have long 3′-untranslated regions; and RRM1 prefers mRNAs with long 3′or 5′-untranslated regions. We suggest that proteins that prefer long mRNAs may have relatively short or degenerate binding sites, and that preferences for A or U increase binding in untranslated regions.
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Roles of the Pumilio domain protein PUF3 in Trypanosoma brucei growth and differentiation. Parasitology 2020; 147:1171-1183. [PMID: 32513341 DOI: 10.1017/s003118202000092x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Trypanosomes strongly rely on post-transcriptional mechanisms to control gene expression. Several Opisthokont Pumilio domain proteins are known to suppress expression when bound to mRNAs. The Trypanosoma brucei Pumilio domain protein PUF3 is a cytosolic mRNA-binding protein that suppresses expression when tethered to a reporter mRNA. RNA-binding studies showed that PUF3 preferentially binds to mRNAs with a classical Pumilio-domain recognition motif, UGUA[U/C]AUU. RNA-interference-mediated reduction of PUF3 in bloodstream forms caused a minor growth defect, but the transcriptome was not affected. Depletion of PUF3 also slightly delayed differentiation to the procyclic form. However, both PUF3 genes could be deleted in cultured bloodstream- and procyclic-form trypanosomes. Procyclic forms without PUF3 also grew somewhat slower than wild-type, but ectopic expression of C-terminally tagged PUF3 impaired their viability. PUF3 was not required for RBP10-induced differentiation of procyclic forms to bloodstream forms. Mass spectrometry revealed no PUF3 binding partners that might explain its suppressive activity. We conclude that PUF3 may have a role in fine-tuning gene expression. Since PUF3 is conserved in all Kinetoplastids, including those that do not infect vertebrates, we suggest that it might confer advantages within the invertebrate host.
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Abstract
In trypanosomes, RNA polymerase II transcription is polycistronic and individual mRNAs are excised by trans-splicing and polyadenylation. The lack of individual gene transcription control is compensated by control of mRNA processing, translation and degradation. Although the basic mechanisms of mRNA decay and translation are evolutionarily conserved, there are also unique aspects, such as the existence of six cap-binding translation initiation factor homologues, a novel decapping enzyme and an mRNA stabilizing complex that is recruited by RNA-binding proteins. High-throughput analyses have identified nearly a hundred regulatory mRNA-binding proteins, making trypanosomes valuable as a model system to investigate post-transcriptional regulation.
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Affiliation(s)
- Christine Clayton
- University of Heidelberg Center for Molecular Biology (ZMBH), Im Neuenheimer Feld 282, D69120 Heidelberg, Germany
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Mudogo CN, Werner SF, Mogk S, Betzel C, Duszenko M. The conserved hypothetical protein Tb427.10.13790 is required for cytokinesis in Trypanosoma brucei. Acta Trop 2018; 188:34-40. [PMID: 30153427 DOI: 10.1016/j.actatropica.2018.08.029] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Revised: 08/22/2018] [Accepted: 08/24/2018] [Indexed: 11/17/2022]
Abstract
Trypanosoma brucei, a flagellated protozoan causing the deadly tropical disease Human African Trypanosomiasis (HAT), affects people in sub-Saharan Africa. HAT therapy relies upon drugs which use is limited by toxicity and rigorous treatment regimes, while development of vaccines remains elusive, due to the effectiveness of the parasite´s antigenic variation. Here, we evaluate a hypothetical protein Tb427.10.13790, as a potential drug target. This protein is conserved among all kinetoplastids, but lacks homologs in all other pro- and eukaryotes. Knockdown of Tb427.10.13790 resulted in appearance of monster cells containing multiple nuclei and multiple flagella, a considerable enlargement of the flagellar pocket and eventually a lethal phenotype. Furthermore, analysis of kinetoplast and nucleus division in the knockdown cell line revealed a partial cell cycle arrest and failure to initiate cytokinesis. Likewise, overexpression of the respective protein fused with enhanced green fluorescent protein was also lethal for T. brucei. In these cells, the labelled protein appeared as a single dot near kinetoplast and flagellar pocket. Our results reveal that Tb427.10.13790 is essential for the parasite´s viability and may be a suitable new anti-trypanosomatid drug target candidate. Furthermore, we suggest that it might be worthwhile to investigate also other of the many so far just annotated trypanosome genes as a considerable number of them to lack human homologs but may be of critical importance for the kinetoplastid parasites.
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Affiliation(s)
- Celestin Nzanzu Mudogo
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany; Institute of Biochemistry and Molecular Biology, University of Hamburg, Laboratory for Structural Biology of Infection and Inflammation, Hamburg, Germany; Department of Basic Sciences, School of Medicine, University of Kinshasa, Democratic Republic of Congo.
| | | | - Stefan Mogk
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany.
| | - Christian Betzel
- Institute of Biochemistry and Molecular Biology, University of Hamburg, Laboratory for Structural Biology of Infection and Inflammation, Hamburg, Germany.
| | - Michael Duszenko
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany; School of Medicine, Tongji University, Shanghai, China.
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Abstract
Protein abundance differs from a few to millions of copies per cell. Trypanosoma brucei presents an excellent model for studies on codon bias and differential gene expression because transcription is broadly unregulated and uniform across the genome. T. brucei is also a major human and animal protozoal pathogen. Here, an experimental assessment, using synthetic reporter genes, revealed that GC3 codons have a major positive impact on both mRNA and protein abundance. Our estimates of relative expression, based on coding sequences alone (codon usage and sequence length), are within 2-fold of the observed values for the majority of measured cellular mRNAs (n > 7000) and proteins (n > 2000). Our estimates also correspond with expression measures from published transcriptome and proteome datasets from other trypanosomatids. We conclude that codon usage is a key factor affecting global relative mRNA and protein expression in trypanosomatids and that relative abundance can be effectively estimated using only protein coding sequences.
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Affiliation(s)
- Laura Jeacock
- Wellcome Trust Centre for Anti-Infectives Research, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Joana Faria
- Wellcome Trust Centre for Anti-Infectives Research, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - David Horn
- Wellcome Trust Centre for Anti-Infectives Research, School of Life Sciences, University of Dundee, Dundee, United Kingdom
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Mulindwa J, Leiss K, Ibberson D, Kamanyi Marucha K, Helbig C, Melo do Nascimento L, Silvester E, Matthews K, Matovu E, Enyaru J, Clayton C. Transcriptomes of Trypanosoma brucei rhodesiense from sleeping sickness patients, rodents and culture: Effects of strain, growth conditions and RNA preparation methods. PLoS Negl Trop Dis 2018; 12:e0006280. [PMID: 29474390 PMCID: PMC5842037 DOI: 10.1371/journal.pntd.0006280] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Revised: 03/07/2018] [Accepted: 01/29/2018] [Indexed: 11/18/2022] Open
Abstract
All of our current knowledge of African trypanosome metabolism is based on results from trypanosomes grown in culture or in rodents. Drugs against sleeping sickness must however treat trypanosomes in humans. We here compare the transcriptomes of Trypanosoma brucei rhodesiense from the blood and cerebrospinal fluid of human patients with those of trypanosomes from culture and rodents. The data were aligned and analysed using new user-friendly applications designed for Kinetoplastid RNA-Seq data. The transcriptomes of trypanosomes from human blood and cerebrospinal fluid did not predict major metabolic differences that might affect drug susceptibility. Usefully, there were relatively few differences between the transcriptomes of trypanosomes from patients and those of similar trypanosomes grown in rats. Transcriptomes of monomorphic laboratory-adapted parasites grown in in vitro culture closely resembled those of the human parasites, but some differences were seen. In poly(A)-selected mRNA transcriptomes, mRNAs encoding some protein kinases and RNA-binding proteins were under-represented relative to mRNA that had not been poly(A) selected; further investigation revealed that the selection tends to result in loss of longer mRNAs.
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Affiliation(s)
- Julius Mulindwa
- Centre for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, Heidelberg, Germany
- Department of Biochemistry and Sports Science, College of Natural Sciences, Makerere University, Kampala, Uganda
| | - Kevin Leiss
- Centre for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, Heidelberg, Germany
| | | | - Kevin Kamanyi Marucha
- Centre for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, Heidelberg, Germany
| | - Claudia Helbig
- Centre for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, Heidelberg, Germany
| | - Larissa Melo do Nascimento
- Centre for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, Heidelberg, Germany
| | - Eleanor Silvester
- Institute for Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Keith Matthews
- Institute for Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Enock Matovu
- Department of Biotechnology and Diagnostic Sciences, College of Veterinary medicine, Animal resources and Biosecurity, Makerere University, Kampala, Uganda
| | - John Enyaru
- Department of Biochemistry and Sports Science, College of Natural Sciences, Makerere University, Kampala, Uganda
| | - Christine Clayton
- Centre for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, Heidelberg, Germany
- * E-mail:
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Azizi H, Dumas C, Papadopoulou B. The Pumilio-domain protein PUF6 contributes to SIDER2 retroposon-mediated mRNA decay in Leishmania. RNA (NEW YORK, N.Y.) 2017; 23:1874-1885. [PMID: 28877997 PMCID: PMC5689007 DOI: 10.1261/rna.062950.117] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Accepted: 09/05/2017] [Indexed: 06/07/2023]
Abstract
Leishmania and other trypanosomatid protozoa lack control at the level of transcription initiation and regulate gene expression exclusively post-transcriptionally. We have reported previously that Leishmania harbors a unique class of short interspersed degenerate retroposons (SIDERs) that are predominantly located within 3'UTRs and play a major role in post-transcriptional control. We have shown that members of the SIDER2 subfamily initiate mRNA decay through endonucleolytic cleavage within the second conserved 79-nt signature sequence of SIDER2 retroposons. Here, we have developed an optimized MS2 coat protein tethering system to capture trans-acting factor(s) regulating SIDER2-mediated mRNA decay. Tethering of the MS2 coat protein to a reporter RNA harboring two MS2 stem-loop aptamers and the cognate SIDER2-containing 3'UTR in combination with immunoprecipitation and mass spectrometry analysis led to the identification of RNA-binding proteins with known functions in mRNA decay. Among the candidate SIDER2-interacting proteins that were individually tethered to a SIDER2 reporter RNA, the Pumilio-domain protein PUF6 was shown to enhance degradation and reduce transcript half-life. Furthermore, we showed that PUF6 binds to SIDER2 sequences that include the regulatory 79-nt signature motif, hence contributing to the mRNA decay process. Consistent with a role of PUF6 in SIDER2-mediated decay, genetic inactivation of PUF6 resulted in increased accumulation and higher stability of endogenous SIDER2-bearing transcripts. Overall, these studies provide new insights into regulated mRNA decay pathways in Leishmania controlled by SIDER2 retroposons and propose a broader role for PUF proteins in mRNA decay within the eukaryotic kingdom.
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Affiliation(s)
- Hiva Azizi
- Research Center in Infectious Diseases, CHU de Quebec Research Center-Laval University, Quebec, QC, G1V 4G2 Canada
- Department of Microbiology, Infectious Diseases and Immunology, Faculty of Medicine, Laval University, Quebec, QC, G1V 0A6 Canada
| | - Carole Dumas
- Research Center in Infectious Diseases, CHU de Quebec Research Center-Laval University, Quebec, QC, G1V 4G2 Canada
- Department of Microbiology, Infectious Diseases and Immunology, Faculty of Medicine, Laval University, Quebec, QC, G1V 0A6 Canada
| | - Barbara Papadopoulou
- Research Center in Infectious Diseases, CHU de Quebec Research Center-Laval University, Quebec, QC, G1V 4G2 Canada
- Department of Microbiology, Infectious Diseases and Immunology, Faculty of Medicine, Laval University, Quebec, QC, G1V 0A6 Canada
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Klein C, Terrao M, Clayton C. The role of the zinc finger protein ZC3H32 in bloodstream-form Trypanosoma brucei. PLoS One 2017; 12:e0177901. [PMID: 28545140 PMCID: PMC5435347 DOI: 10.1371/journal.pone.0177901] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Accepted: 05/04/2017] [Indexed: 01/06/2023] Open
Abstract
Kinetoplastids rely heavily on post-transcriptional mechanisms for control of gene expression, with regulation of mRNA processing, translation and degradation by RNA-binding proteins. ZC3H32 is a cytosolic mRNA-binding protein with three non-canonical CCCH zinc finger domains. It is much more abundant in bloodstream-form Trypanosoma brucei than in procyclic forms. Tethering of ZC3H32 to a reporter mRNA suppressed translation and resulted in mRNA degradation, and deletion analysis suggested that this activity was present in both the N- and C-terminal domains, but not the central zinc finger-containing domain. Tandem affinity purification, however, revealed no interaction partners that might account for this activity. RNASeq analyses did not yield any evidence for sequence-specific binding or regulation of specific mRNAs. The presence of ZC3H32 homologues in monogenetic and free-living Euglenids also argues against a role in developmental regulation, although its function may have diverged in evolution. T. brucei ZC3H32 might be implicated in basal mRNA metabolism, with this role perhaps being taken over by another protein in procyclic forms.
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Affiliation(s)
- Cornelia Klein
- Centre for Molecular Biology of Heidelberg University, DKFZ-ZMBH Alliance, Heidelberg, Germany
| | - Monica Terrao
- Centre for Molecular Biology of Heidelberg University, DKFZ-ZMBH Alliance, Heidelberg, Germany
| | - Christine Clayton
- Centre for Molecular Biology of Heidelberg University, DKFZ-ZMBH Alliance, Heidelberg, Germany
- * E-mail:
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12
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Clayton CE. Gene expression in Kinetoplastids. Curr Opin Microbiol 2016; 32:46-51. [PMID: 27177350 DOI: 10.1016/j.mib.2016.04.018] [Citation(s) in RCA: 115] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Revised: 04/18/2016] [Accepted: 04/21/2016] [Indexed: 12/17/2022]
Abstract
Kinetoplastid parasites adapt to different environments with wide-reaching control of gene expression, but transcription of nuclear protein-coding genes is polycistronic: there is no individual control of transcription initiation. Mature mRNAs are made by co-transcriptional trans splicing and polyadenylation, and competition between processing and nuclear degradation may contribute to regulation of mRNA levels. In the cytosol both the extent to which mRNAs are translated, and mRNA decay rates, vary enormously. I here highlight gaps in our knowledge: no measurements of transcription initiation or elongation rates; no measurements of how, precisely, mRNA processing and nuclear degradation control mRNA levels; and extremely limited understanding of the contributions of different translation initiation factors and RNA-binding proteins to mRNA fate.
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Affiliation(s)
- C E Clayton
- Universität Heidelberg Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, 69120 Heidelberg, Germany.
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13
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Antwi EB, Haanstra JR, Ramasamy G, Jensen B, Droll D, Rojas F, Minia I, Terrao M, Mercé C, Matthews K, Myler PJ, Parsons M, Clayton C. Integrative analysis of the Trypanosoma brucei gene expression cascade predicts differential regulation of mRNA processing and unusual control of ribosomal protein expression. BMC Genomics 2016; 17:306. [PMID: 27118143 PMCID: PMC4845500 DOI: 10.1186/s12864-016-2624-3] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Accepted: 04/16/2016] [Indexed: 11/25/2022] Open
Abstract
Background Trypanosoma brucei is a unicellular parasite which multiplies in mammals (bloodstream form) and Tsetse flies (procyclic form). Trypanosome RNA polymerase II transcription is polycistronic, individual mRNAs being excised by trans splicing and polyadenylation. We previously made detailed measurements of mRNA half-lives in bloodstream and procyclic forms, and developed a mathematical model of gene expression for bloodstream forms. At the whole transcriptome level, many bloodstream-form mRNAs were less abundant than was predicted by the model. Results We refined the published mathematical model and extended it to the procyclic form. We used the model, together with known mRNA half-lives, to predict the abundances of individual mRNAs, assuming rapid, unregulated mRNA processing; then we compared the results with measured mRNA abundances. Remarkably, the abundances of most mRNAs in procyclic forms are predicted quite well by the model, being largely explained by variations in mRNA decay rates and length. In bloodstream forms substantially more mRNAs are less abundant than predicted. We list mRNAs that are likely to show particularly slow or inefficient processing, either in both forms or with developmental regulation. We also measured ribosome occupancies of all mRNAs in trypanosomes grown in the same conditions as were used to measure mRNA turnover. In procyclic forms there was a weak positive correlation between ribosome density and mRNA half-life, suggesting cross-talk between translation and mRNA decay; ribosome density was related to the proportion of the mRNA on polysomes, indicating control of translation initiation. Ribosomal protein mRNAs in procyclics appeared to be exceptionally rapidly processed but poorly translated. Conclusions Levels of mRNAs in procyclic form trypanosomes are determined mainly by length and mRNA decay, with some control of precursor processing. In bloodstream forms variations in nuclear events play a larger role in transcriptome regulation, suggesting aquisition of new control mechanisms during adaptation to mammalian parasitism. Electronic supplementary material The online version of this article (doi:10.1186/s12864-016-2624-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Enoch B Antwi
- Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, D-69120, Heidelberg, Germany
| | - Jurgen R Haanstra
- Department of Molecular Cell Physiology, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081 HV, Amsterdam, The Netherlands.,Systems Bioinformatics, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081 HV, Amsterdam, The Netherlands
| | - Gowthaman Ramasamy
- Center for Infectious Disease Research (formerly Seattle Biomedical Research Institute), 307 Westlake Ave N, Seattle, WA, 98109-5219, USA
| | - Bryan Jensen
- Center for Infectious Disease Research (formerly Seattle Biomedical Research Institute), 307 Westlake Ave N, Seattle, WA, 98109-5219, USA
| | - Dorothea Droll
- Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, D-69120, Heidelberg, Germany.,Current address: Biology of Host Parasite Interactions, 25 rue du Docteur Roux, 75724, Paris cedex 15, France
| | - Federico Rojas
- Centre for Immunity, Infection and Evolution, Institute for Immunology and infection Research, School of Biological Sciences, Ashworth Laboratories, University of Edinburgh, West Mains Road, Edinburgh, EH9 3JT, UK
| | - Igor Minia
- Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, D-69120, Heidelberg, Germany
| | - Monica Terrao
- Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, D-69120, Heidelberg, Germany
| | - Clémentine Mercé
- Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, D-69120, Heidelberg, Germany
| | - Keith Matthews
- Centre for Immunity, Infection and Evolution, Institute for Immunology and infection Research, School of Biological Sciences, Ashworth Laboratories, University of Edinburgh, West Mains Road, Edinburgh, EH9 3JT, UK
| | - Peter J Myler
- Center for Infectious Disease Research (formerly Seattle Biomedical Research Institute), 307 Westlake Ave N, Seattle, WA, 98109-5219, USA.,Department of Global Health, University of Washington, Harris Hydraulics Building, 1705 NE Pacific St #310E, Box 357965, Seattle, WA, 98195, USA.,Department of Biomedical Informatics and Medical Education, University of Washington, Seattle, WA, 98195, USA
| | - Marilyn Parsons
- Center for Infectious Disease Research (formerly Seattle Biomedical Research Institute), 307 Westlake Ave N, Seattle, WA, 98109-5219, USA.,Department of Global Health, University of Washington, Harris Hydraulics Building, 1705 NE Pacific St #310E, Box 357965, Seattle, WA, 98195, USA
| | - Christine Clayton
- Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, D-69120, Heidelberg, Germany.
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Lueong S, Merce C, Fischer B, Hoheisel JD, Erben ED. Gene expression regulatory networks in Trypanosoma brucei: insights into the role of the mRNA-binding proteome. Mol Microbiol 2016; 100:457-71. [PMID: 26784394 DOI: 10.1111/mmi.13328] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/14/2016] [Indexed: 12/11/2022]
Abstract
Control of gene expression at the post-transcriptional level is essential in all organisms, and RNA-binding proteins play critical roles from mRNA synthesis to decay. To fully understand this process, it is necessary to identify the complete set of RNA-binding proteins and the functional consequences of the protein-mRNA interactions. Here, we provide an overview of the proteins that bind to mRNAs and their functions in the pathogenic bloodstream form of Trypanosoma brucei. We describe the production of a small collection of open-reading frames encoding proteins potentially involved in mRNA metabolism. With this ORFeome collection, we used tethering to screen for proteins that play a role in post-transcriptional control. A yeast two-hybrid screen showed that several of the discovered repressors interact with components of the CAF1/NOT1 deadenylation complex. To identify the RNA-binding proteins, we obtained the mRNA-bound proteome. We identified 155 high-confidence candidates, including many not previously annotated as RNA-binding proteins. Twenty seven of these proteins affected reporter expression in the tethering screen. Our study provides novel insights into the potential trypanosome mRNPs composition, architecture and function.
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Affiliation(s)
- Smiths Lueong
- Functional Genome Analysis, Deutsche Krebsforschungszentrum (DKFZ), Im Neuenheimer Feld 580, 69120 Heidelberg, Germany
| | - Clementine Merce
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282
| | - Bernd Fischer
- Computational Genome Biology, Deutsches Krebsforschungszentrum (DKFZ), Im Neuenheimer Feld 580, 69120 Heidelberg
| | - Jörg D Hoheisel
- Functional Genome Analysis, Deutsche Krebsforschungszentrum (DKFZ), Im Neuenheimer Feld 580, 69120 Heidelberg, Germany
| | - Esteban D Erben
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282
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15
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Mulindwa J, Mercé C, Matovu E, Enyaru J, Clayton C. Transcriptomes of newly-isolated Trypanosoma brucei rhodesiense reveal hundreds of mRNAs that are co-regulated with stumpy-form markers. BMC Genomics 2015; 16:1118. [PMID: 26715446 PMCID: PMC4696300 DOI: 10.1186/s12864-015-2338-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Accepted: 12/22/2015] [Indexed: 12/02/2022] Open
Abstract
Background During natural Trypanosoma brucei infections, the parasites differentiate spontaneously into a non-dividing “stumpy” form when a certain level of parasitaemia is attained. This form is metabolically adapted for rapid further differentiation into procyclic forms upon uptake by Tsetse flies. Results We describe here four central Ugandan isolates of Trypanosoma brucei rhodesiense that have undergone only three rodent passages since isolation from human patients. As expected, SNP analysis shows that these isolates are more closely related to each other than to the commonly used strains Lister 427, Antat1.1, and TREU927. TREU927 generally has smaller copy numbers of repeated genes than the other strains, while Lister 427 trypanosomes with a 30-year history of in vitro culture and cloning have more histone genes than the other isolates. The recently isolated trypanosomes were grown in rats, and their transcriptomes characterised. In comparison with cultured procyclic and bloodstream forms, there were increases in mRNAs encoding the stumpy-form markers ESAG9 and PIP39, with coordinated alterations in the levels of over 600 additional mRNAs. Numerous mRNAs encoding proteins of no known function were either increased or decreased. The products of the mRNAs that were increased in parallel with PIP39 included not only enzymes of procyclic-form metabolism, but also components of the translational and RNA control machineries. Many of the mRNAs that were decreased in cells with elevated PIP39 reflected reduced cell division. Conclusions These transcriptomes suggest new avenues for research into the regulation of trypanosome differentiation. Electronic supplementary material The online version of this article (doi:10.1186/s12864-015-2338-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Julius Mulindwa
- Department of Biochemistry and Sports Science, College of Natural Sciences, Makerere University, P.O.Box 7062, Kampala, Uganda. .,Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, D-69120, Heidelberg, Germany.
| | - Clémentine Mercé
- Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, D-69120, Heidelberg, Germany.
| | - Enock Matovu
- Department of Biotechnical and Diagnostic Sciences, College of Veterinary Medicine, Animal Resources and Biosecurity, Makerere University, P.O.Box 7062, Kampala, Uganda.
| | - John Enyaru
- Department of Biochemistry and Sports Science, College of Natural Sciences, Makerere University, P.O.Box 7062, Kampala, Uganda.
| | - Christine Clayton
- Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, D-69120, Heidelberg, Germany.
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16
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Polysomes of Trypanosoma brucei: Association with Initiation Factors and RNA-Binding Proteins. PLoS One 2015; 10:e0135973. [PMID: 26287607 PMCID: PMC4545788 DOI: 10.1371/journal.pone.0135973] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Accepted: 07/28/2015] [Indexed: 12/16/2022] Open
Abstract
We report here the results of experiments designed to identify RNA-binding proteins that might be associated with Trypanosoma brucei polysomes. After some preliminary mass spectrometry of polysomal fractions, we investigated the distributions of selected tagged proteins using sucrose gradients and immunofluorescence. As expected, the polysomal fractions contained nearly all annotated ribosomal proteins, the translation-associated protein folding complex, and many translation factors, but also many other abundant proteins. Results suggested that cap-binding proteins EIF4E3 and EIF4E4 were associated with both free and membrane-bound polysomes. The EIF4E binding partners EIF4G4 and EIF4G3 were present but the other EIF4E and EIF4G paralogues were not detected. The dominant EIF4E in the polysomal fraction is EIF4E4 and very few polysomal mRNAs are associated with EIF4G. Thirteen potential mRNA-binding proteins were detected in the polysomes, including the known polysome-associated protein RBP42. The locations of two of the other proteins were tested after epitope tagging: RBP29 was in the nucleus and ZC3H29 was in the cytoplasm. Quantitative analyses showed that specific association of an RNA-binding protein with the polysome fraction in sucrose gradients will not be detected if the protein is in more than 25-fold molar excess over its target binding sites.
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17
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Bühlmann M, Walrad P, Rico E, Ivens A, Capewell P, Naguleswaran A, Roditi I, Matthews KR. NMD3 regulates both mRNA and rRNA nuclear export in African trypanosomes via an XPOI-linked pathway. Nucleic Acids Res 2015; 43:4491-504. [PMID: 25873624 PMCID: PMC4482084 DOI: 10.1093/nar/gkv330] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Revised: 03/30/2015] [Accepted: 03/31/2015] [Indexed: 02/03/2023] Open
Abstract
Trypanosomes mostly regulate gene expression through post-transcriptional mechanisms, particularly mRNA stability. However, much mRNA degradation is cytoplasmic such that mRNA nuclear export must represent an important level of regulation. Ribosomal RNAs must also be exported from the nucleus and the trypanosome orthologue of NMD3 has been confirmed to be involved in rRNA processing and export, matching its function in other organisms. Surprisingly, we found that TbNMD3 depletion also generates mRNA accumulation of procyclin-associated genes (PAGs), these being co-transcribed by RNA polymerase I with the procyclin surface antigen genes expressed on trypanosome insect forms. By whole transcriptome RNA-seq analysis of TbNMD3-depleted cells we confirm the regulation of the PAG transcripts by TbNMD3 and using reporter constructs reveal that PAG1 regulation is mediated by its 5'UTR. Dissection of the mechanism of regulation demonstrates that it is not dependent upon translational inhibition mediated by TbNMD3 depletion nor enhanced transcription. However, depletion of the nuclear export factors XPO1 or MEX67 recapitulates the effects of TbNMD3 depletion on PAG mRNAs and mRNAs accumulated in the nucleus of TbNMD3-depleted cells. These results invoke a novel RNA regulatory mechanism involving the NMD3-dependent nuclear export of mRNA cargos, suggesting a shared platform for mRNA and rRNA export.
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Affiliation(s)
- Melanie Bühlmann
- Centre for Immunity, Infection and Evolution, Institute for Immunology and Infection Research, School of Biological Sciences, Kings Buildings, University of Edinburgh, West Mains Road, Edinburgh EH9 3JT, UK
| | - Pegine Walrad
- Centre for Immunity, Infection and Evolution, Institute for Immunology and Infection Research, School of Biological Sciences, Kings Buildings, University of Edinburgh, West Mains Road, Edinburgh EH9 3JT, UK Centre for Immunology and Infection, Department of Biology, University of York, YO10 5DD, UK
| | - Eva Rico
- Centre for Immunity, Infection and Evolution, Institute for Immunology and Infection Research, School of Biological Sciences, Kings Buildings, University of Edinburgh, West Mains Road, Edinburgh EH9 3JT, UK
| | - Alasdair Ivens
- Centre for Immunity, Infection and Evolution, Institute for Immunology and Infection Research, School of Biological Sciences, Kings Buildings, University of Edinburgh, West Mains Road, Edinburgh EH9 3JT, UK
| | - Paul Capewell
- Centre for Immunity, Infection and Evolution, Institute for Immunology and Infection Research, School of Biological Sciences, Kings Buildings, University of Edinburgh, West Mains Road, Edinburgh EH9 3JT, UK
| | | | - Isabel Roditi
- Institute of Cell Biology, University of Bern, CH-3012 Bern, Switzerland
| | - Keith R Matthews
- Centre for Immunity, Infection and Evolution, Institute for Immunology and Infection Research, School of Biological Sciences, Kings Buildings, University of Edinburgh, West Mains Road, Edinburgh EH9 3JT, UK
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18
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Abstract
TbRRM1 of Trypanosoma brucei is a nucleoprotein that was previously identified in a search for splicing factors in T. brucei. We show that TbRRM1 associates with mRNAs and with the auxiliary splicing factor polypyrimidine tract-binding protein 2, but not with components of the core spliceosome. TbRRM1 also interacts with several retrotransposon hot spot (RHS) proteins and histones. RNA immunoprecipitation of a tagged form of TbRRM1 from procyclic (insect) form trypanosomes identified ca. 1,500 transcripts that were enriched and 3,000 transcripts that were underrepresented compared to cellular mRNA. Enriched transcripts encoded RNA-binding proteins, including TbRRM1 itself, several RHS transcripts, mRNAs with long coding regions, and a high proportion of stage-regulated mRNAs that are more highly expressed in bloodstream forms. Transcripts encoding ribosomal proteins, other factors involved in translation, and procyclic-specific transcripts were underrepresented. Knockdown of TbRRM1 by RNA interference caused widespread changes in mRNA abundance, but these changes did not correlate with the binding of the protein to transcripts, and most splice sites were unchanged, negating a general role for TbRRM1 in splice site selection. When changes in mRNA abundance were mapped across the genome, regions with many downregulated mRNAs were identified. Two regions were analyzed by chromatin immunoprecipitation, both of which exhibited increases in nucleosome occupancy upon TbRRM1 depletion. In addition, subjecting cells to heat shock resulted in translocation of TbRRM1 to the cytoplasm and compaction of chromatin, consistent with a second role for TbRRM1 in modulating chromatin structure. Trypanosoma brucei, the parasite that causes human sleeping sickness, is transmitted by tsetse flies. The parasite progresses through different life cycle stages in its two hosts, altering its pattern of gene expression in the process. In trypanosomes, protein-coding genes are organized as polycistronic units that are processed into monocistronic mRNAs. Since genes in the same unit can be regulated independently of each other, it is believed that gene regulation is essentially posttranscriptional. In this study, we investigated the role of a nuclear RNA-binding protein, TbRRM1, in the insect stage of the parasite. We found that TbRRM1 binds nuclear mRNAs and also affects chromatin status. Reduction of nuclear TbRRM1 by RNA interference or heat shock resulted in chromatin compaction. We propose that TbRRM1 regulates RNA polymerase II-driven gene expression both cotranscriptionally, by facilitating transcription and efficient splicing, and posttranscriptionally, via its interaction with nuclear mRNAs.
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Fadda A, Ryten M, Droll D, Rojas F, Färber V, Haanstra JR, Merce C, Bakker BM, Matthews K, Clayton C. Transcriptome-wide analysis of trypanosome mRNA decay reveals complex degradation kinetics and suggests a role for co-transcriptional degradation in determining mRNA levels. Mol Microbiol 2014; 94:307-26. [PMID: 25145465 PMCID: PMC4285177 DOI: 10.1111/mmi.12764] [Citation(s) in RCA: 92] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/19/2014] [Indexed: 01/14/2023]
Abstract
African trypanosomes are an excellent system for quantitative modelling of post-transcriptional mRNA control. Transcription is constitutive and polycistronic; individual mRNAs are excised by trans splicing and polyadenylation. We here measure mRNA decay kinetics in two life cycle stages, bloodstream and procyclic forms, by transcription inhibition and RNASeq. Messenger RNAs with short half-lives tend to show initial fast degradation, followed by a slower phase; they are often stabilized by depletion of the 5′–3′ exoribonuclease XRNA. Many longer-lived mRNAs show initial slow degradation followed by rapid destruction: we suggest that the slow phase reflects gradual deadenylation. Developmentally regulated mRNAs often show regulated decay, and switch their decay pattern. Rates of mRNA decay are good predictors of steady state levels for short mRNAs, but mRNAs longer than 3 kb show unexpectedly low abundances. Modelling shows that variations in splicing and polyadenylation rates can contribute to steady-state mRNA levels, but this is completely dependent on competition between processing and co-transcriptional mRNA precursor destruction.
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Affiliation(s)
- Abeer Fadda
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, 69120, Heidelberg, Germany
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