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Ballmer D, Akiyoshi B. Dynamic localization of the chromosomal passenger complex in trypanosomes is controlled by the orphan kinesins KIN-A and KIN-B. eLife 2024; 13:RP93522. [PMID: 38564240 PMCID: PMC10987093 DOI: 10.7554/elife.93522] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/04/2024] Open
Abstract
The chromosomal passenger complex (CPC) is an important regulator of cell division, which shows dynamic subcellular localization throughout mitosis, including kinetochores and the spindle midzone. In traditional model eukaryotes such as yeasts and humans, the CPC consists of the catalytic subunit Aurora B kinase, its activator INCENP, and the localization module proteins Borealin and Survivin. Intriguingly, Aurora B and INCENP as well as their localization pattern are conserved in kinetoplastids, an evolutionarily divergent group of eukaryotes that possess unique kinetochore proteins and lack homologs of Borealin or Survivin. It is not understood how the kinetoplastid CPC assembles nor how it is targeted to its subcellular destinations during the cell cycle. Here, we identify two orphan kinesins, KIN-A and KIN-B, as bona fide CPC proteins in Trypanosoma brucei, the kinetoplastid parasite that causes African sleeping sickness. KIN-A and KIN-B form a scaffold for the assembly of the remaining CPC subunits. We show that the C-terminal unstructured tail of KIN-A interacts with the KKT8 complex at kinetochores, while its N-terminal motor domain promotes CPC translocation to spindle microtubules. Thus, the KIN-A:KIN-B complex constitutes a unique 'two-in-one' CPC localization module, which directs the CPC to kinetochores from S phase until metaphase and to the central spindle in anaphase. Our findings highlight the evolutionary diversity of CPC proteins and raise the possibility that kinesins may have served as the original transport vehicles for Aurora kinases in early eukaryotes.
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Affiliation(s)
- Daniel Ballmer
- Department of Biochemistry, University of OxfordOxfordUnited Kingdom
- The Wellcome Centre for Cell Biology, Institute of Cell Biology, School of Biological SciencesEdinburghUnited Kingdom
| | - Bungo Akiyoshi
- Department of Biochemistry, University of OxfordOxfordUnited Kingdom
- The Wellcome Centre for Cell Biology, Institute of Cell Biology, School of Biological SciencesEdinburghUnited Kingdom
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2
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Briggs EM, Marques CA, Oldrieve GR, Hu J, Otto TD, Matthews KR. Profiling the bloodstream form and procyclic form Trypanosoma brucei cell cycle using single-cell transcriptomics. eLife 2023; 12:e86325. [PMID: 37166108 PMCID: PMC10212563 DOI: 10.7554/elife.86325] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Accepted: 05/10/2023] [Indexed: 05/12/2023] Open
Abstract
African trypanosomes proliferate as bloodstream forms (BSFs) and procyclic forms in the mammal and tsetse fly midgut, respectively. This allows them to colonise the host environment upon infection and ensure life cycle progression. Yet, understanding of the mechanisms that regulate and drive the cell replication cycle of these forms is limited. Using single-cell transcriptomics on unsynchronised cell populations, we have obtained high resolution cell cycle regulated (CCR) transcriptomes of both procyclic and slender BSF Trypanosoma brucei without prior cell sorting or synchronisation. Additionally, we describe an efficient freeze-thawing protocol that allows single-cell transcriptomic analysis of cryopreserved T. brucei. Computational reconstruction of the cell cycle using periodic pseudotime inference allowed the dynamic expression patterns of cycling genes to be profiled for both life cycle forms. Comparative analyses identify a core cycling transcriptome highly conserved between forms, as well as several genes where transcript levels dynamics are form specific. Comparing transcript expression patterns with protein abundance revealed that the majority of genes with periodic cycling transcript and protein levels exhibit a relative delay between peak transcript and protein expression. This work reveals novel detail of the CCR transcriptomes of both forms, which are available for further interrogation via an interactive webtool.
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Affiliation(s)
- Emma M Briggs
- Institute for Immunology and Infection Research, School of Biological Sciences, University of EdinburghEdinburghUnited Kingdom
- Wellcome Centre for Integrative Parasitology, School of Infection & Immunity, University of GlasgowGlasgowUnited Kingdom
| | - Catarina A Marques
- Wellcome Centre for Integrative Parasitology, School of Infection & Immunity, University of GlasgowGlasgowUnited Kingdom
| | - Guy R Oldrieve
- Institute for Immunology and Infection Research, School of Biological Sciences, University of EdinburghEdinburghUnited Kingdom
| | - Jihua Hu
- Institute for Immunology and Infection Research, School of Biological Sciences, University of EdinburghEdinburghUnited Kingdom
| | - Thomas D Otto
- Wellcome Centre for Integrative Parasitology, School of Infection & Immunity, University of GlasgowGlasgowUnited Kingdom
| | - Keith R Matthews
- Institute for Immunology and Infection Research, School of Biological Sciences, University of EdinburghEdinburghUnited Kingdom
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3
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Kasozi KI, MacLeod ET, Ntulume I, Welburn SC. An Update on African Trypanocide Pharmaceutics and Resistance. Front Vet Sci 2022; 9:828111. [PMID: 35356785 PMCID: PMC8959112 DOI: 10.3389/fvets.2022.828111] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Accepted: 01/12/2022] [Indexed: 12/22/2022] Open
Abstract
African trypanosomiasis is associated with Trypanosoma evansi, T. vivax, T. congolense, and T. brucei pathogens in African animal trypanosomiasis (AAT) while T. b gambiense and T. b rhodesiense are responsible for chronic and acute human African trypanosomiasis (HAT), respectively. Suramin sodium suppresses ATP generation during the glycolytic pathway and is ineffective against T. vivax and T. congolense infections. Resistance to suramin is associated with pathogen altered transport proteins. Melarsoprol binds irreversibly with pyruvate kinase protein sulfhydryl groups and neutralizes enzymes which interrupts the trypanosome ATP generation. Melarsoprol resistance is associated with the adenine-adenosine transporter, P2, due to point mutations within this transporter. Eflornithine is used in combination with nifurtimox. Resistance to eflornithine is caused by the deletion or mutation of TbAAT6 gene which encodes the transmembrane amino acid transporter that delivers eflornithine into the cell, thus loss of transporter protein results in eflornithine resistance. Nifurtimox alone is regarded as a poor trypanocide, however, it is effective in melarsoprol-resistant gHAT patients. Resistance is associated with loss of a single copy of the genes encoding for nitroreductase enzymes. Fexinidazole is recommended for first-stage and non-severe second-stage illnesses in gHAT and resistance is associated with trypanosome bacterial nitroreductases which reduce fexinidazole. In AAT, quinapyramine sulfate interferes with DNA synthesis and suppression of cytoplasmic ribosomal activity in the mitochondria. Quinapyramine sulfate resistance is due to variations in the potential of the parasite's mitochondrial membrane. Pentamidines create cross-links between two adenines at 4–5 pairs apart in adenine-thymine-rich portions of Trypanosoma DNA. It also suppresses type II topoisomerase in the mitochondria of Trypanosoma parasites. Pentamidine resistance is due to loss of mitochondria transport proteins P2 and HAPT1. Diamidines are most effective against Trypanosome brucei group and act via the P2/TbAT1 transporters. Diminazene aceturate resistance is due to mutations that alter the activity of P2, TeDR40 (T. b. evansi). Isometamidium chloride is primarily employed in the early stages of trypanosomiasis and resistance is associated with diminazene resistance. Phenanthridine (homidium bromide, also known as ethidium bromide) acts by a breakdown of the kinetoplast network and homidium resistance is comparable to isometamidium. In humans, the development of resistance and adverse side effects against monotherapies has led to the adoption of nifurtimox-eflornithine combination therapy. Current efforts to develop new prodrug combinations of nifurtimox and eflornithine and nitroimidazole fexinidazole as well as benzoxaborole SCYX-7158 (AN5568) for HAT are in progress while little comparable progress has been done for the development of novel therapies to address trypanocide resistance in AAT.
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Affiliation(s)
- Keneth Iceland Kasozi
- Infection Medicine, Deanery of Biomedical Sciences, College of Medicine and Veterinary Medicine, The University of Edinburgh, Edinburgh, United Kingdom
- School of Medicine, Kabale University, Kabale, Uganda
- *Correspondence: Keneth Iceland Kasozi ;
| | - Ewan Thomas MacLeod
- Infection Medicine, Deanery of Biomedical Sciences, College of Medicine and Veterinary Medicine, The University of Edinburgh, Edinburgh, United Kingdom
| | - Ibrahim Ntulume
- School of Biosecurity Biotechnical and Laboratory Sciences, College of Medicine and Veterinary Medicine, Makerere University, Kampala, Uganda
| | - Susan Christina Welburn
- Infection Medicine, Deanery of Biomedical Sciences, College of Medicine and Veterinary Medicine, The University of Edinburgh, Edinburgh, United Kingdom
- Zhejiang University-University of Edinburgh Joint Institute, Zhejiang University, Hangzhou, China
- Susan Christina Welburn
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Oxidative Phosphorylation Is Required for Powering Motility and Development of the Sleeping Sickness Parasite Trypanosoma brucei in the Tsetse Fly Vector. mBio 2022; 13:e0235721. [PMID: 35012336 PMCID: PMC8749461 DOI: 10.1128/mbio.02357-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The single-celled parasite Trypanosoma brucei is transmitted by hematophagous tsetse flies. Life cycle progression from mammalian bloodstream form to tsetse midgut form and, subsequently, infective salivary gland form depends on complex developmental steps and migration within different fly tissues. As the parasite colonizes the glucose-poor insect midgut, ATP production is thought to depend on activation of mitochondrial amino acid catabolism via oxidative phosphorylation (OXPHOS). This process involves respiratory chain complexes and F1Fo-ATP synthase and requires protein subunits of these complexes that are encoded in the parasite's mitochondrial DNA (kDNA). Here, we show that progressive loss of kDNA-encoded functions correlates with a decreasing ability to initiate and complete development in the tsetse. First, parasites with a mutated F1Fo-ATP synthase with reduced capacity for OXPHOS can initiate differentiation from bloodstream to insect form, but they are unable to proliferate in vitro. Unexpectedly, these cells can still colonize the tsetse midgut. However, these parasites exhibit a motility defect and are severely impaired in colonizing or migrating to subsequent tsetse tissues. Second, parasites with a fully disrupted F1Fo-ATP synthase complex that is completely unable to produce ATP by OXPHOS can still differentiate to the first insect stage in vitro but die within a few days and cannot establish a midgut infection in vivo. Third, parasites lacking kDNA entirely can initiate differentiation but die soon after. Together, these scenarios suggest that efficient ATP production via OXPHOS is not essential for initial colonization of the tsetse vector but is required to power trypanosome migration within the fly. IMPORTANCE African trypanosomes cause disease in humans and their livestock and are transmitted by tsetse flies. The insect ingests these parasites with its blood meal, but to be transmitted to another mammal, the trypanosome must undergo complex development within the tsetse fly and migrate from the insect's gut to its salivary glands. Crucially, the parasite must switch from a sugar-based diet while in the mammal to a diet based primarily on amino acids when it develops in the insect. Here, we show that efficient energy production by an organelle called the mitochondrion is critical for the trypanosome's ability to swim and to migrate through the tsetse fly. Surprisingly, trypanosomes with impaired mitochondrial energy production are only mildly compromised in their ability to colonize the tsetse fly midgut. Our study adds a new perspective to the emerging view that infection of tsetse flies by trypanosomes is more complex than previously thought.
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Benz C, Urbaniak MD. Synchronization of Trypanosoma brucei by Counter-Flow Centrifugal Elutriation. Methods Mol Biol 2022; 2579:137-144. [PMID: 36045204 DOI: 10.1007/978-1-0716-2736-5_11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Centrifugal counter-flow elutriation is a non-invasive technique that separates cells based on their hydrodynamic volume in a specialized centrifugation chamber that allows the application of a counter-flow of buffer to oppose sedimentation. Here, we report a centrifugal counter-flow elutriation protocol for Trypanosoma brucei cells that is able to rapidly isolate highly enriched G1 subpopulations (>95%) of synchronized cells. The cells obtained are viable and proliferate without lag, allowing subsequent cell cycle phases to be obtained by continued culture. The synchronized cell cultures obtained by this process have uniform DNA content, a narrow size distribution, undergo synchronous division, and maintain synchrony into subsequent cell cycles.
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Affiliation(s)
- Corinna Benz
- Division of Biomedical and Life Sciences, Faculty of Health and Medicine, Lancaster University, Lancaster, UK
| | - Michael D Urbaniak
- Division of Biomedical and Life Sciences, Faculty of Health and Medicine, Lancaster University, Lancaster, UK.
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6
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Trypanosoma brucei Tim50 Possesses PAP Activity and Plays a Critical Role in Cell Cycle Regulation and Parasite Infectivity. mBio 2021; 12:e0159221. [PMID: 34517757 PMCID: PMC8546626 DOI: 10.1128/mbio.01592-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Trypanosoma brucei, the infective agent for African trypanosomiasis, possesses a homologue of the translocase of the mitochondrial inner membrane 50 (TbTim50). It has a pair of characteristic phosphatase signature motifs, DXDX(T/V). Here, we demonstrated that, besides its protein phosphatase activity, the recombinant TbTim50 binds and hydrolyzes phosphatidic acid in a concentration-dependent manner. Mutations of D242 and D244, but not of D345and D347, to alanine abolished these activities. In silico structural homology models identified the putative binding interfaces that may accommodate different phosphosubstrates. Interestingly, TbTim50 depletion in the bloodstream form (BF) of T. brucei reduced cardiolipin (CL) levels and decreased mitochondrial membrane potential (ΔΨ). TbTim50 knockdown (KD) also reduced the population of G2/M phase and increased that of G1 phase cells; inhibited segregation and caused overreplication of kinetoplast DNA (kDNA), and reduced BF cell growth. Depletion of TbTim50 increased the levels of AMPK phosphorylation, and parasite morphology was changed with upregulation of expression of a few stumpy marker genes. Importantly, we observed that TbTim50-depleted parasites were unable to establish infection in mice. Proteomics analysis showed reductions in levels of the translation factors, flagellar transport proteins, and many proteasomal subunits, including those of the mitochondrial heat shock locus ATPase (HslVU), which is known to play a role in regulation of kinetoplast DNA (kDNA) replication. Reduction of the level of HslV in TbTim50 KD cells was further validated by immunoblot analysis. Together, our results showed that TbTim50 is essential for mitochondrial function, regulation of kDNA replication, and the cell cycle in the BF. Therefore, TbTim50 is an important target for structure-based drug design to combat African trypanosomiasis.
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Malfara MF, Silverberg LJ, DiMaio J, Lagalante AF, Olsen MA, Madison E, Povelones ML. 2,3-Diphenyl-2,3-dihydro-4H-1,3-thiaza-4-one heterocycles inhibit growth and block completion of cytokinesis in kinetoplastid parasites. Mol Biochem Parasitol 2021; 245:111396. [PMID: 34302898 DOI: 10.1016/j.molbiopara.2021.111396] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Revised: 07/07/2021] [Accepted: 07/09/2021] [Indexed: 11/16/2022]
Abstract
Kinetoplastid parasites are model eukaryotes with a complex cell cycle that is highly regulated both spatially and temporally. In addition, diseases caused by these parasites continue to have a significant impact on human and animal health worldwide. While there have been advancements in chemotherapy for these diseases, there is a continual need for an arsenal of compounds that have robust anti-parasite activity with minimal impact on the human host. While investigating a series of 2,3-diphenyl-2,3-dihydro-4H-1,3-thiaza-4-one heterocycles with potential activity against these parasites, we found a pyridothiazinone that inhibits growth of the monoxenous parasite Crithidia fasciculata and two life cycle stages of Trypanosoma brucei. This inhibition is more pronounced in T. brucei and is associated with an unusual pre-abscission cell cycle arrest. Exploring the mode of action for these and related compounds in kinetoplastids may provide tools with which to explore cell cycle regulation in these important organisms.
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Affiliation(s)
| | - Lee J Silverberg
- Pennsylvania State University, Schuylkill Campus, Schuylkill Haven, PA, 17972, USA
| | - John DiMaio
- Pennsylvania State University, Brandywine Campus, Media, PA, 19063, USA
| | | | - Mark A Olsen
- Department of Chemistry, Villanova University, Villanova, PA, 19085, USA
| | - Ekaterina Madison
- Pennsylvania State University, Brandywine Campus, Media, PA, 19063, USA
| | - Megan L Povelones
- Department of Biology, Villanova University, Villanova, PA, 19085, USA.
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8
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Lee KJ, Li Z. The CRK2-CYC13 complex functions as an S-phase cyclin-dependent kinase to promote DNA replication in Trypanosoma brucei. BMC Biol 2021; 19:29. [PMID: 33568178 PMCID: PMC7876812 DOI: 10.1186/s12915-021-00961-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Accepted: 01/15/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Faithful DNA replication is essential to maintain genomic stability in all living organisms, and the regulatory pathway for DNA replication initiation is conserved from yeast to humans. The evolutionarily ancient human parasite Trypanosoma brucei, however, lacks many of the conserved DNA replication factors and may employ unusual mechanisms for DNA replication. Neither the S-phase cyclin-dependent kinase (CDK) nor the regulatory pathway governing DNA replication has been previously identified in T. brucei. RESULTS Here we report that CRK2 (Cdc2-related kinase 2) complexes with CYC13 (Cyclin13) and functions as an S-phase CDK to promote DNA replication in T. brucei. We further show that CRK2 phosphorylates Mcm3, a subunit of the Mcm2-7 sub-complex of the Cdc45-Mcm2-7-GINS complex, and demonstrate that Mcm3 phosphorylation by CRK2 facilitates interaction with Sld5, a subunit of the GINS sub-complex of the Cdc45-Mcm2-7-GINS complex. CONCLUSIONS These results identify the CRK2-CYC13 complex as an S-phase regulator in T. brucei and reveal its role in regulating DNA replication through promoting the assembly of the Cdc45-Mcm2-7-GINS complex.
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Affiliation(s)
- Kyu Joon Lee
- Department of Microbiology and Molecular Genetics, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX, 77030, USA
| | - Ziyin Li
- Department of Microbiology and Molecular Genetics, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX, 77030, USA.
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Kurasawa Y, An T, Li Z. Polo-like kinase in trypanosomes: an odd member out of the Polo family. Open Biol 2020; 10:200189. [PMID: 33050792 PMCID: PMC7653357 DOI: 10.1098/rsob.200189] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 09/17/2020] [Indexed: 12/12/2022] Open
Abstract
Polo-like kinases (Plks) are evolutionarily conserved serine/threonine protein kinases playing crucial roles during multiple stages of mitosis and cytokinesis in yeast and animals. Plks are characterized by a unique Polo-box domain, which plays regulatory roles in controlling Plk activation, interacting with substrates and targeting Plk to specific subcellular locations. Plk activity and protein abundance are subject to temporal and spatial control through transcription, phosphorylation and proteolysis. In the early branching protists, Plk orthologues are present in some taxa, such as kinetoplastids and Giardia, but are lost in apicomplexans, such as Plasmodium. Works from characterizing a Plk orthologue in Trypanosoma brucei, a kinetoplastid protozoan, discover its essential roles in regulating the inheritance of flagellum-associated cytoskeleton and the initiation of cytokinesis, but not any stage of mitosis. These studies reveal evolutionarily conserved and species-specific features in the control of Plk activation, substrate recognition and protein abundance, and suggest the divergence of Plk function and regulation for specialized needs in this flagellated unicellular eukaryote.
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Affiliation(s)
| | | | - Ziyin Li
- Department of Microbiology and Molecular Genetics, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX 77030, USA
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Pérez-Posada A, Dudin O, Ocaña-Pallarès E, Ruiz-Trillo I, Ondracka A. Cell cycle transcriptomics of Capsaspora provides insights into the evolution of cyclin-CDK machinery. PLoS Genet 2020; 16:e1008584. [PMID: 32176685 PMCID: PMC7098662 DOI: 10.1371/journal.pgen.1008584] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Revised: 03/26/2020] [Accepted: 12/23/2019] [Indexed: 12/19/2022] Open
Abstract
Progression through the cell cycle in eukaryotes is regulated on multiple levels. The main driver of the cell cycle progression is the periodic activity of cyclin-dependent kinase (CDK) complexes. In parallel, transcription during the cell cycle is regulated by a transcriptional program that ensures the just-in-time gene expression. Many core cell cycle regulators are widely conserved in eukaryotes, among them cyclins and CDKs; however, periodic transcriptional programs are divergent between distantly related species. In addition, many otherwise conserved cell cycle regulators have been lost and independently evolved in yeast, a widely used model organism for cell cycle research. For a better understanding of the evolution of the cell cycle regulation in opisthokonts, we investigated the transcriptional program during the cell cycle of the filasterean Capsaspora owczarzaki, a unicellular species closely related to animals. We developed a protocol for cell cycle synchronization in Capsaspora cultures and assessed gene expression over time across the entire cell cycle. We identified a set of 801 periodic genes that grouped into five clusters of expression over time. Comparison with datasets from other eukaryotes revealed that the periodic transcriptional program of Capsaspora is most similar to that of animal cells. We found that orthologues of cyclin A, B and E are expressed at the same cell cycle stages as in human cells and in the same temporal order. However, in contrast to human cells where these cyclins interact with multiple CDKs, Capsaspora cyclins likely interact with a single ancestral CDK1-3. Thus, the Capsaspora cyclin-CDK system could represent an intermediate state in the evolution of animal-like cyclin-CDK regulation. Overall, our results demonstrate that Capsaspora could be a useful unicellular model system for animal cell cycle regulation.
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Affiliation(s)
- Alberto Pérez-Posada
- Institut de Biologia Evolutiva (CSIC-Universitat Pompeu Fabra), Barcelona, Catalonia, Spain
| | - Omaya Dudin
- Institut de Biologia Evolutiva (CSIC-Universitat Pompeu Fabra), Barcelona, Catalonia, Spain
| | - Eduard Ocaña-Pallarès
- Institut de Biologia Evolutiva (CSIC-Universitat Pompeu Fabra), Barcelona, Catalonia, Spain
| | - Iñaki Ruiz-Trillo
- Institut de Biologia Evolutiva (CSIC-Universitat Pompeu Fabra), Barcelona, Catalonia, Spain
- Departament de Genètica, Microbiologia i Estadística, Universitat de Barcelona, Barcelona, Catalonia, Spain
- ICREA, Barcelona, Catalonia, Spain
| | - Andrej Ondracka
- Institut de Biologia Evolutiva (CSIC-Universitat Pompeu Fabra), Barcelona, Catalonia, Spain
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11
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Benz C, Urbaniak MD. Organising the cell cycle in the absence of transcriptional control: Dynamic phosphorylation co-ordinates the Trypanosoma brucei cell cycle post-transcriptionally. PLoS Pathog 2019; 15:e1008129. [PMID: 31830130 PMCID: PMC6907760 DOI: 10.1371/journal.ppat.1008129] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Accepted: 10/07/2019] [Indexed: 11/18/2022] Open
Abstract
The cell division cycle of the unicellular eukaryote Trypanosome brucei is tightly regulated despite the paucity of transcriptional control that results from the arrangement of genes in polycistronic units and lack of dynamically regulated transcription factors. To identify the contribution of dynamic phosphorylation to T. brucei cell cycle control we have combined cell cycle synchronisation by centrifugal elutriation with quantitative phosphoproteomic analysis. Cell cycle regulated changes in phosphorylation site abundance (917 sites, average 5-fold change) were more widespread and of a larger magnitude than changes in protein abundance (443 proteins, average 2-fold change) and were mostly independent of each other. Hierarchical clustering of co-regulated phosphorylation sites according to their cell cycle profile revealed that a bulk increase in phosphorylation occurs across the cell cycle, with a significant enrichment of known cell cycle regulators and RNA binding proteins (RBPs) within the largest clusters. Cell cycle regulated changes in essential cell cycle kinases are temporally co-ordinated with differential phosphorylation of components of the kinetochore and eukaryotic initiation factors, along with many RBPs not previously linked to the cell cycle such as eight PSP1-C terminal domain containing proteins. The temporal profiles demonstrate the importance of dynamic phosphorylation in co-ordinating progression through the cell cycle, and provide evidence that RBPs play a central role in post-transcriptional regulation of the T. brucei cell cycle. Data are available via ProteomeXchange with identifier PXD013488.
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Affiliation(s)
- Corinna Benz
- Biomedical and Life Sciences, Faculty of Health and Medicine, Lancaster University, Lancaster, United Kingdom
| | - Michael D. Urbaniak
- Biomedical and Life Sciences, Faculty of Health and Medicine, Lancaster University, Lancaster, United Kingdom
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12
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Hu H, An T, Kurasawa Y, Zhou Q, Li Z. The trypanosome-specific proteins FPRC and CIF4 regulate cytokinesis initiation by recruiting CIF1 to the cytokinesis initiation site. J Biol Chem 2019; 294:16672-16683. [PMID: 31540971 DOI: 10.1074/jbc.ra119.010538] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Revised: 09/18/2019] [Indexed: 11/06/2022] Open
Abstract
The evolutionarily early divergent human parasite Trypanosoma brucei proliferates through binary cell fission in both its tsetse fly vector and mammalian host. The parasite divides unidirectionally along the longitudinal cell axis from the anterior cell tip toward the posterior cell tip through a mechanism distinct from that in the cells of its human host. Initiation of cytokinesis in T. brucei is regulated by two evolutionarily conserved protein kinases, the Polo-like kinase TbPLK and the Aurora B kinase TbAUK1, and a cohort of trypanosome-specific proteins, including the three cytokinesis initiation factors CIF1, CIF2, and CIF3. Here, using RNAi, in situ epitope tagging of proteins, GST pulldown, and coimmunoprecipitation assays, and immunofluorescence and scanning electron microscopy analyses, we report the identification and functional characterization of two trypanosome-specific proteins, flagellum attachment zone tip-localizing protein required for cytokinesis (FPRC) and CIF4. We found that the two proteins colocalize to the distal tips of the new and the old flagellum attachment zones and are required for cytokinesis initiation. Knockdown of FPRC or CIF4 disrupted the localization of CIF1, suggesting that they function upstream of CIF1. Moreover, depletion of CIF4 abolished FPRC localization, indicating that CIF4 acts upstream of FPRC. Together, these results identify two new cytokinesis regulators in T. brucei and integrate them into the CIF1-mediated cytokinesis regulatory pathway. These findings highlight the existence of a cytokinesis pathway in T. brucei that is different from that of its mammalian host and therefore suggest that cytokinesis in T. brucei could potentially be exploited as a new drug target.
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Affiliation(s)
- Huiqing Hu
- Department of Microbiology and Molecular Genetics, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, Texas 77030
| | - Tai An
- Department of Microbiology and Molecular Genetics, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, Texas 77030
| | - Yasuhiro Kurasawa
- Department of Microbiology and Molecular Genetics, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, Texas 77030
| | - Qing Zhou
- Department of Microbiology and Molecular Genetics, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, Texas 77030
| | - Ziyin Li
- Department of Microbiology and Molecular Genetics, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, Texas 77030
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Abstract
Trypanosomes have complex life cycles within which there are both proliferative and differentiation cell divisions. The coordination of the cell cycle to achieve these different divisions is critical for the parasite to infect both host and vector. From studying the regulation of the proliferative cell cycle of the Trypanosoma brucei procyclic life cycle stage, three subcycles emerge that control the duplication and segregation of ( a) the nucleus, ( b) the kinetoplast, and ( c) a set of cytoskeletal structures. We discuss how the clear dependency relationships within these subcycles, and the potential for cross talk between them, are likely required for overall cell cycle coordination. Finally, we look at the implications this interdependence has for proliferative and differentiation divisions through the T. brucei life cycle and in related parasitic trypanosomatid species.
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Affiliation(s)
- Richard J. Wheeler
- Nuffield Department of Medicine, University of Oxford, Oxford OX1 3SY, United Kingdom
| | - Keith Gull
- Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, United Kingdom
| | - Jack D. Sunter
- Department of Biological and Medical Sciences, Oxford Brookes University, Oxford OX3 0BP, United Kingdom
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14
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Prestes EB, Stoco PH, de Moraes MH, Moura H, Grisard EC. Messenger RNA levels of the Polo-like kinase gene (PLK) correlate with cytokinesis in the Trypanosoma rangeli cell cycle. Exp Parasitol 2019; 204:107727. [PMID: 31344389 DOI: 10.1016/j.exppara.2019.107727] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2019] [Revised: 07/06/2019] [Accepted: 07/21/2019] [Indexed: 10/26/2022]
Abstract
BACKGROUND Trypanosoma rangeli is a protozoan parasite that is non-virulent to the mammalian host and is morphologically and genomically related to Trypanosoma cruzi, whose proliferation within the mammalian host is controversially discussed. OBJECTIVES We aimed to investigate the T. rangeli cell cycle in vitro and in vivo by characterizing the timespan of the parasite life cycle and by proposing a molecular marker to assess cytokinesis. METHODOLOGY The morphological events and their timing during the cell cycle of T. rangeli epimastigotes were assessed using DNA staining, flagellum labelling and bromodeoxyuridine incorporation. Messenger RNA levels of four genes previously associated with the cell cycle of trypanosomatids (AUK1, PLK, MOB1 and TRACK) were evaluated in the different T. rangeli forms. FINDINGS T. rangeli epimastigotes completed the cell cycle in vitro in 20.8 h. PLK emerged as a potential molecular marker for cell division, as its mRNA levels were significantly increased in exponentially growing epimastigotes compared with growth-arrested parasites or in vitro-differentiated trypomastigotes. PLK expression in T. rangeli can be detected near the flagellum protrusion site, reinforcing its role in the cell cycle. Interestingly, T. rangeli bloodstream trypomastigotes exhibited very low mRNA levels of PLK and were almost entirely composed of parasites in G1 phase. MAIN CONCLUSIONS Our work is the first to describe the T. rangeli cell cycle in vitro and proposes that PLK mRNA levels could be a useful tool to investigate the T. rangeli ability to proliferate within the mammalian host bloodstream.
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Affiliation(s)
- Elisa Beatriz Prestes
- Laboratórios de Protozoologia e de Bioinformática, MIP/CCB, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil; Laboratório de Inflamação e Imunidade, IMPG/CCS, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
| | - Patrícia Hermes Stoco
- Laboratórios de Protozoologia e de Bioinformática, MIP/CCB, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil
| | - Milene Höehr de Moraes
- Laboratórios de Protozoologia e de Bioinformática, MIP/CCB, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil
| | - Hércules Moura
- Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention (CDC), Atlanta, GA, USA
| | - Edmundo Carlos Grisard
- Laboratórios de Protozoologia e de Bioinformática, MIP/CCB, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil.
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15
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Kim HS. Genome-wide function of MCM-BP in Trypanosoma brucei DNA replication and transcription. Nucleic Acids Res 2019; 47:634-647. [PMID: 30407533 PMCID: PMC6344857 DOI: 10.1093/nar/gky1088] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Accepted: 10/21/2018] [Indexed: 12/13/2022] Open
Abstract
In Trypanosoma brucei, genes are arranged in Polycistronic Transcription Units (PTUs), which are demarcated by transcription start and stop sites. Transcription start sites are also binding sites of Origin Recognition Complex 1 (ORC1). This spatial coincidence implies that transcription and replication in trypanosomes must occur in a highly ordered and cooperative manner. Interestingly, a previously published genetic screen identified the T. brucei MCM-BP, which interacts with subunits of MCM helicase, as a protein whose downregulation results in the loss of transcriptional silencing at subtelomeric loci. Here, I show that TbMCM-BP is required for DNA replication and transcription. TbMCM-BP depletion causes a significant reduction of replicating cells in S phase and genome-wide impairments of replication origin activation. Moreover, levels of sense and antisense transcripts increase at boundaries of PTUs in the absence of TbMCM-BP. TbMCM-BP is also important for transcriptional repression of the specialized subtelomeric PTUs, the Bloodstream-form Expression-Sites (BESs), which house the major antigenic determinant (the Variant Surface Glycoprotein, VSG gene) as well as TbORC1 binding sites. Overall, this study reveals that TbMCM-BP, a replication initiation protein, also guides the initiation, termination and directionality of transcription.
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Affiliation(s)
- Hee-Sook Kim
- Laboratory of Lymphocyte Biology, Rockefeller University, 1275 York Avenue, New York, NY 10065, USA.,Department of Biological, Geological, and Environmental Sciences, Center for Gene Regulation in Health and Disease, Cleveland State University, 2121 Euclid Avenue, Cleveland, OH 44115, USA
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16
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Glover L, Marques CA, Suska O, Horn D. Persistent DNA Damage Foci and DNA Replication with a Broken Chromosome in the African Trypanosome. mBio 2019; 10:e01252-19. [PMID: 31289179 PMCID: PMC6747728 DOI: 10.1128/mbio.01252-19] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Accepted: 06/06/2019] [Indexed: 02/06/2023] Open
Abstract
Damaged DNA typically imposes stringent controls on eukaryotic cell cycle progression, ensuring faithful transmission of genetic material. Some DNA breaks, and the resulting rearrangements, are advantageous, however. For example, antigenic variation in the parasitic African trypanosome, Trypanosoma brucei, relies upon homologous recombination-based rearrangements of telomeric variant surface glycoprotein (VSG) genes, triggered by breaks. Surprisingly, trypanosomes with a severed telomere continued to grow while progressively losing subtelomeric DNA, suggesting a nominal telomeric DNA damage checkpoint response. Here, we monitor the single-stranded DNA-binding protein replication protein A (RPA) in response to induced, locus-specific DNA breaks in T. brucei RPA foci accumulated at nucleolar sites following a break within ribosomal DNA and at extranucleolar sites following a break elsewhere, including adjacent to transcribed or silent telomeric VSG genes. As in other eukaryotes, RPA foci were formed in S phase and γH2A and RAD51 damage foci were disassembled prior to mitosis. Unlike in other eukaryotes, however, and regardless of the damaged locus, RPA foci persisted through the cell cycle, and these cells continued to replicate their DNA. We conclude that a DNA break, regardless of the damaged locus, fails to trigger a stringent cell cycle checkpoint in T. brucei This DNA damage tolerance may facilitate the generation of virulence-enhancing genetic diversity, within subtelomeric domains in particular. Stringent checkpoints may be similarly lacking in some other eukaryotic cells.IMPORTANCE Chromosome damage must be repaired to prevent the proliferation of defective cells. Alternatively, cells with damage must be eliminated. This is true of human and several other cell types but may not be the case for single-celled parasites, such as trypanosomes. African trypanosomes, which cause lethal diseases in both humans and livestock, can actually exploit chromosomal damage to activate new surface coat proteins and to evade host immune responses, for example. We monitored responses to single chromosomal breaks in trypanosomes using a DNA-binding protein that, in response to DNA damage, forms nuclear foci visible using a microscope. Surprisingly, and unlike what is seen in mammalian cells, these foci persist while cells continue to divide. We also demonstrate chromosome replication even when one chromosome is broken. These results reveal a remarkable degree of damage tolerance in trypanosomes, which may suit the lifestyle of a single-celled parasite, potentially facilitating adaptation and enhancing virulence.
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Affiliation(s)
- Lucy Glover
- Wellcome Trust Centre for Anti-Infectives Research, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Catarina A Marques
- Wellcome Trust Centre for Anti-Infectives Research, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Olga Suska
- 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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17
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Functional Analyses of Cytokinesis Regulators in Bloodstream Stage Trypanosoma brucei Parasites Identify Functions and Regulations Specific to the Life Cycle Stage. mSphere 2019; 4:4/3/e00199-19. [PMID: 31043517 PMCID: PMC6495339 DOI: 10.1128/msphere.00199-19] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
The early divergent protozoan parasite Trypanosoma brucei is the causative agent of sleeping sickness in humans and nagana in cattle in sub-Saharan Africa. This parasite has a complex life cycle by alternating between the insect vector and the mammalian hosts and proliferates by binary cell fission. The control of cell division in trypanosomes appears to be distinct from that in its human host and differs substantially between two life cycle stages, the procyclic (insect) form and the bloodstream form. Cytokinesis, the final step of binary cell fission, is regulated by a novel signaling cascade consisting of two evolutionarily conserved protein kinases and a cohort of trypanosome-specific regulators in the procyclic form, but whether this signaling pathway operates in a similar manner in the bloodstream form is unclear. In this report, we performed a functional analysis of multiple cytokinesis regulators and discovered their distinct functions and regulations in the bloodstream form. The early divergent protozoan parasite Trypanosoma brucei alternates between the insect vector and the mammalian hosts during its life cycle and proliferates through binary cell fission. The cell cycle control system in T. brucei differs substantially from that in its mammalian hosts and possesses distinct mitosis-cytokinesis checkpoint controls between two life cycle stages, the procyclic form and the bloodstream form. T. brucei undergoes an unusual mode of cytokinesis, which is controlled by a novel signaling cascade consisting of evolutionarily conserved protein kinases and trypanosome-specific regulatory proteins in the procyclic form. However, given the distinct mitosis-cytokinesis checkpoints between the two forms, it is unclear whether the cytokinesis regulatory pathway discovered in the procyclic form also operates in a similar manner in the bloodstream form. Here, we showed that the three regulators of cytokinesis initiation, cytokinesis initiation factor 1 (CIF1), CIF2, and CIF3, are interdependent for subcellular localization but not for protein stability as in the procyclic form. Further, we demonstrated that KLIF, a regulator of cytokinesis completion in the procyclic form, plays limited roles in cytokinesis in the bloodstream form. Finally, we showed that the cleavage furrow-localizing protein FRW1 is required for cytokinesis initiation in the bloodstream form but is nonessential for cytokinesis in the procyclic form. Together, these results identify conserved and life cycle-specific functions of cytokinesis regulators, highlighting the distinction in the regulation of cytokinesis between different life cycle stages of T. brucei. IMPORTANCE The early divergent protozoan parasite Trypanosoma brucei is the causative agent of sleeping sickness in humans and nagana in cattle in sub-Saharan Africa. This parasite has a complex life cycle by alternating between the insect vector and the mammalian hosts and proliferates by binary cell fission. The control of cell division in trypanosomes appears to be distinct from that in its human host and differs substantially between two life cycle stages, the procyclic (insect) form and the bloodstream form. Cytokinesis, the final step of binary cell fission, is regulated by a novel signaling cascade consisting of two evolutionarily conserved protein kinases and a cohort of trypanosome-specific regulators in the procyclic form, but whether this signaling pathway operates in a similar manner in the bloodstream form is unclear. In this report, we performed a functional analysis of multiple cytokinesis regulators and discovered their distinct functions and regulations in the bloodstream form.
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18
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The DNA damage response is developmentally regulated in the African trypanosome. DNA Repair (Amst) 2018; 73:78-90. [PMID: 30470509 PMCID: PMC6329875 DOI: 10.1016/j.dnarep.2018.11.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Revised: 10/12/2018] [Accepted: 11/12/2018] [Indexed: 01/19/2023]
Abstract
Genomes are affected by a wide range of damage, which has resulted in the evolution of a number of widely conserved DNA repair pathways. Most of these repair reactions have been described in the African trypanosome Trypanosoma brucei, which is a genetically tractable eukaryotic microbe and important human and animal parasite, but little work has considered how the DNA damage response operates throughout the T. brucei life cycle. Using quantitative PCR we have assessed damage induction and repair in both the nuclear and mitochondrial genomes of the parasite. We show differing kinetics of repair for three forms of DNA damage, and dramatic differences in repair between replicative life cycle forms found in the testse fly midgut and the mammal. We find that mammal-infective T. brucei cells repair oxidative and crosslink-induced DNA damage more efficiently than tsetse-infective cells and, moreover, very distinct patterns of induction and repair of DNA alkylating damage in the two life cycle forms. We also reveal robust repair of DNA lesions in the highly unusual T. brucei mitochondrial genome (the kinetoplast). By examining mutants we show that nuclear alkylation damage is repaired by the concerted action of two repair pathways, and that Rad51 acts in kinetoplast repair. Finally, we correlate repair with cell cycle arrest and cell growth, revealing that induced DNA damage has strikingly differing effects on the two life cycle stages, with distinct timing of alkylation-induced cell cycle arrest and higher levels of damage induced death in mammal-infective cells. Our data reveal that T. brucei regulates the DNA damage response during its life cycle, a capacity that may be shared by many microbial pathogens that exist in variant environments during growth and transmission.
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19
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Hilton NA, Sladewski TE, Perry JA, Pataki Z, Sinclair-Davis AN, Muniz RS, Tran HL, Wurster JI, Seo J, de Graffenried CL. Identification of TOEFAZ1-interacting proteins reveals key regulators of Trypanosoma brucei cytokinesis. Mol Microbiol 2018; 109:306-326. [PMID: 29781112 PMCID: PMC6359937 DOI: 10.1111/mmi.13986] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/13/2018] [Indexed: 01/07/2023]
Abstract
The protist parasite Trypanosoma brucei is an obligate extracellular pathogen that retains its highly polarized morphology during cell division and has evolved a novel cytokinetic process independent of non-muscle myosin II. The polo-like kinase homolog TbPLK is essential for transmission of cell polarity during division and for cytokinesis. We previously identified a putative TbPLK substrate named Tip of the Extending FAZ 1 (TOEFAZ1) as an essential kinetoplastid-specific component of the T. brucei cytokinetic machinery. We performed a proximity-dependent biotinylation identification (BioID) screen using TOEFAZ1 as a means to identify additional proteins that are involved in cytokinesis. Using quantitative proteomic methods, we identified nearly 500 TOEFAZ1-proximal proteins and characterized 59 in further detail. Among the candidates, we identified an essential putative phosphatase that regulates the expression level and localization of both TOEFAZ1 and TbPLK, a previously uncharacterized protein that is necessary for the assembly of a new cell posterior, and a microtubule plus-end directed orphan kinesin that is required for completing cleavage furrow ingression. The identification of these proteins provides new insight into T. brucei cytokinesis and establishes TOEFAZ1 as a key component of this essential and uniquely configured process in kinetoplastids.
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Affiliation(s)
- Nicholas A. Hilton
- Department of Molecular Microbiology and Immunology, Brown University, Providence, RI, 02912
| | - Thomas E. Sladewski
- Department of Molecular Microbiology and Immunology, Brown University, Providence, RI, 02912
| | - Jenna A. Perry
- Department of Molecular Microbiology and Immunology, Brown University, Providence, RI, 02912
| | - Zemplen Pataki
- Department of Molecular Microbiology and Immunology, Brown University, Providence, RI, 02912
| | - Amy N. Sinclair-Davis
- Department of Molecular Microbiology and Immunology, Brown University, Providence, RI, 02912
| | - Richard S. Muniz
- Department of Molecular Microbiology and Immunology, Brown University, Providence, RI, 02912
| | - Holly L. Tran
- Department of Molecular Microbiology and Immunology, Brown University, Providence, RI, 02912
| | - Jenna I. Wurster
- Department of Molecular Microbiology and Immunology, Brown University, Providence, RI, 02912
| | - Jiwon Seo
- Department of Molecular Biology, Cell Biology, and Biochemistry, Brown University, Providence, RI, 02912
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20
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Santos CMBD, Ludwig A, Kessler RL, Rampazzo RDCP, Inoue AH, Krieger MA, Pavoni DP, Probst CM. Trypanosoma cruzi transcriptome during axenic epimastigote growth curve. Mem Inst Oswaldo Cruz 2018; 113:e170404. [PMID: 29668769 PMCID: PMC5907844 DOI: 10.1590/0074-02760170404] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Accepted: 01/29/2018] [Indexed: 01/23/2023] Open
Abstract
BACKGROUND Trypanosoma cruzi is an important protozoan parasite and the causative agent of Chagas disease. A critical step in understanding T. cruzi biology is the study of cellular and molecular features exhibited during its growth curve. OBJECTIVES We aimed to acquire a global view of the gene expression profile of T. cruzi during epimastigote growth. METHODS RNA-Seq analysis of total and polysomal/granular RNA fractions was performed along the 10 days T. cruzi epimastigote growth curve in vitro, in addition to cell viability and cell cycle analyses. We also analysed the polysome profile and investigated the presence of granular RNA by FISH and western blotting. FINDINGS We identified 1082 differentially expressed genes (DEGs), of which 220 were modulated in both fractions. According to the modulation pattern, DEGs were grouped into 12 clusters and showed enrichment of important gene ontology (GO) terms. Moreover, we showed that by the sixth day of the growth curve, polysomal content declined greatly and the RNA granules content appeared to increase, suggesting that a portion of mRNAs isolated from the sucrose gradient during late growth stages was associated with RNA granules and not only polyribosomes. Furthermore, we discuss several modulated genes possibly involved in T. cruzi growth, mainly during the stationary phase, such as genes related to cell cycle, pathogenesis, metabolic processes and RNA-binding proteins.
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Affiliation(s)
| | - Adriana Ludwig
- Instituto Carlos Chagas, Fundação Oswaldo Cruz, Curitiba, PR, Brasil
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21
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Abstract
Kinetoplastids have a nucleus that contains the nuclear genome and a kinetoplast that contains the mitochondrial genome. These single-copy organelles must be duplicated and segregated faithfully to daughter cells at each cell division. In Trypanosoma brucei, although duplication of both organelles starts around the same time, segregation of the kinetoplast precedes that of the nucleus. Cytokinesis subsequently takes place so that daughter cells inherit a single copy of each organelle. Very little is known about the molecular mechanism that governs the timing of these events. Furthermore, it is thought that T. brucei lacks a spindle checkpoint that delays the onset of nuclear division in response to spindle defects. Here we show that a mitotic cyclin CYC6 has a dynamic localization pattern during the cell cycle, including kinetochore localization. Using CYC6 as a molecular cell cycle marker, we confirmed that T. brucei cannot delay the onset of anaphase in response to a bipolar spindle assembly defect. Interestingly, expression of a stabilized form of CYC6 caused the nucleus to arrest in a metaphase-like state without preventing cytokinesis. We propose that trypanosomes have an ability to regulate the timing of nuclear division by modulating the CYC6 protein level, without a spindle checkpoint.
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Affiliation(s)
- Hanako Hayashi
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK
| | - Bungo Akiyoshi
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK
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22
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Machado FC, Franco CH, Dos Santos Neto JV, Dias-Teixeira KL, Moraes CB, Lopes UG, Aktas BH, Schenkman S. Identification of di-substituted ureas that prevent growth of trypanosomes through inhibition of translation initiation. Sci Rep 2018; 8:4857. [PMID: 29559670 PMCID: PMC5861040 DOI: 10.1038/s41598-018-23259-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Accepted: 03/08/2018] [Indexed: 01/25/2023] Open
Abstract
Some 1,3-diarylureas and 1-((1,4-trans)−4-aryloxycyclohexyl)−3-arylureas (cHAUs) activate heme-regulated kinase causing protein synthesis inhibition via phosphorylation of the eukaryotic translation initiation factor 2 (eIF2) in mammalian cancer cells. To evaluate if these agents have potential to inhibit trypanosome multiplication by also affecting the phosphorylation of eIF2 alpha subunit (eIF2α), we tested 25 analogs of 1,3-diarylureas and cHAUs against Trypanosoma cruzi, the agent of Chagas disease. One of them (I-17) presented selectivity close to 10-fold against the insect replicative forms and also inhibited the multiplication of T. cruzi inside mammalian cells with an EC50 of 1–3 µM and a selectivity of 17-fold. I-17 also prevented replication of African trypanosomes (Trypanosoma brucei bloodstream and procyclic forms) at similar doses. It caused changes in the T. cruzi morphology, arrested parasite cell cycle in G1 phase, and promoted phosphorylation of eIF2α with a robust decrease in ribosome association with mRNA. The activity against T. brucei also implicates eIF2α phosphorylation, as replacement of WT-eIF2α with a non-phosphorylatable eIF2α, or knocking down eIF2 protein kinase-3 by RNAi increased resistance to I-17. Therefore, we demonstrate that eIF2α phosphorylation can be engaged to develop trypanosome-static agents in general, and particularly by interfering with activity of eIF2 kinases.
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Affiliation(s)
- Fabricio Castro Machado
- Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, 04039-032, São Paulo, SP, Brazil
| | - Caio Haddad Franco
- Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, 04039-032, São Paulo, SP, Brazil.,Instituto Butantan, São Paulo, SP, Brazil
| | - Jose Vitorino Dos Santos Neto
- Laboratório de Parasitologia Molecular, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Karina Luiza Dias-Teixeira
- Laboratório de Parasitologia Molecular, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Carolina Borsoi Moraes
- Instituto Butantan, São Paulo, SP, Brazil.,Departamento de Microbiologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, SP, Brazil
| | - Ulisses Gazos Lopes
- Laboratório de Parasitologia Molecular, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Bertal Huseyin Aktas
- Hematology Laboratory for Translational Research, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, 75 Francis Street, Boston, MA, 02115, United States.
| | - Sergio Schenkman
- Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, 04039-032, São Paulo, SP, Brazil.
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23
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Crozier TWM, Tinti M, Wheeler RJ, Ly T, Ferguson MAJ, Lamond AI. Proteomic Analysis of the Cell Cycle of Procylic Form Trypanosoma brucei. Mol Cell Proteomics 2018; 17:1184-1195. [PMID: 29555687 PMCID: PMC5986242 DOI: 10.1074/mcp.ra118.000650] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Revised: 03/01/2018] [Indexed: 12/24/2022] Open
Abstract
We describe a single-step centrifugal elutriation method to produce synchronous Gap1 (G1)-phase procyclic trypanosomes at a scale amenable for proteomic analysis of the cell cycle. Using ten-plex tandem mass tag (TMT) labeling and mass spectrometry (MS)-based proteomics technology, the expression levels of 5325 proteins were quantified across the cell cycle in this parasite. Of these, 384 proteins were classified as cell-cycle regulated and subdivided into nine clusters with distinct temporal regulation. These groups included many known cell cycle regulators in trypanosomes, which validates the approach. In addition, we identify 40 novel cell cycle regulated proteins that are essential for trypanosome survival and thus represent potential future drug targets for the prevention of trypanosomiasis. Through cross-comparison to the TrypTag endogenous tagging microscopy database, we were able to validate the cell-cycle regulated patterns of expression for many of the proteins of unknown function detected in our proteomic analysis. A convenient interface to access and interrogate these data is also presented, providing a useful resource for the scientific community. Data are available via ProteomeXchange with identifier PXD008741 (https://www.ebi.ac.uk/pride/archive/).
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Affiliation(s)
- Thomas W M Crozier
- From the ‡Wellcome Centre for Anti-Infectives Research, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK.,§Centre for Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK
| | - Michele Tinti
- From the ‡Wellcome Centre for Anti-Infectives Research, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK
| | - Richard J Wheeler
- ‖Sir William Dunn School of Pathology, University of Oxford, Oxford, OX1 3RE, UK
| | - Tony Ly
- §Centre for Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK
| | - Michael A J Ferguson
- From the ‡Wellcome Centre for Anti-Infectives Research, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK;
| | - Angus I Lamond
- §Centre for Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK;
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24
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Morriswood B, Engstler M. Let's get fISSical: fast in silico synchronization as a new tool for cell division cycle analysis. Parasitology 2018; 145:196-209. [PMID: 28166845 PMCID: PMC5964468 DOI: 10.1017/s0031182017000038] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Revised: 12/23/2016] [Accepted: 01/05/2017] [Indexed: 12/23/2022]
Abstract
Cell cycle progression is a question of fundamental biological interest. The coordinated duplication and segregation of all cellular structures and organelles is however an extremely complex process, and one which remains only partially understood even in the most intensively researched model organisms. Trypanosomes are in an unusual position in this respect - they are both outstanding model systems for fundamental questions in eukaryotic cell biology, and pathogens that are the causative agents of three of the neglected tropical diseases. As a failure to successfully complete cell division will be deleterious or lethal, analysis of the cell division cycle is of relevance both to basic biology and drug design efforts. Cell division cycle analysis is however experimentally challenging, as the analysis of phenotypes associated with it remains hypothesis-driven and therefore biased. Current methods of analysis are extremely labour-intensive, and cell synchronization remains difficult and unreliable. Consequently, there exists a need - both in basic and applied trypanosome biology - for a global, unbiased, standardized and high-throughput analysis of cell division cycle progression. In this review, the requirements - both practical and computational - for such a system are considered and compared with existing techniques for cell cycle analysis.
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Affiliation(s)
- Brooke Morriswood
- Department of Cell & Developmental Biology,University of Würzburg,Biocentre, Am Hubland, 97074 Würzburg,Germany
| | - Markus Engstler
- Department of Cell & Developmental Biology,University of Würzburg,Biocentre, Am Hubland, 97074 Würzburg,Germany
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Benz C, Dondelinger F, McKean PG, Urbaniak MD. Cell cycle synchronisation of Trypanosoma brucei by centrifugal counter-flow elutriation reveals the timing of nuclear and kinetoplast DNA replication. Sci Rep 2017; 7:17599. [PMID: 29242601 PMCID: PMC5730572 DOI: 10.1038/s41598-017-17779-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Accepted: 11/29/2017] [Indexed: 01/06/2023] Open
Abstract
We report an optimised centrifugal counter-flow elutriation protocol for the rapid and direct isolation of G1 cell cycle synchronised populations of both the procyclic and bloodstream form stages of Trypanosoma brucei that yields viable and proliferative cells. The high quality of the synchronisation achieved can be judged by the uniform DNA content, narrow size distribution, synchronous division, and the maintenance of synchronicity into subsequent cell cycles. We show that early-eluting fractions represent different G1 subpopulations that progress through the cell cycle with distinct temporal profiles post-elutriation, as exemplified by the observation of the maturation of a second flagellar basal body in late G1 phase, DNA replication in S phase, and dimethylation of histone H3 in mitosis/cytokinesis. We use our temporal observations to construct a revised model of the relative timing and duration of the nuclear and kinetoplast cell cycle that differs from the current model.
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Affiliation(s)
- Corinna Benz
- Biomedical and Life Sciences, Faculty of Health and Medicine, Lancaster University, Lancaster, LA1 4YG, UK
| | - Frank Dondelinger
- Lancaster Medical School, Faculty of Health and Medicine, Lancaster University, Lancaster, LA1 4YG, UK
| | - Paul G McKean
- Biomedical and Life Sciences, Faculty of Health and Medicine, Lancaster University, Lancaster, LA1 4YG, UK
| | - Michael D Urbaniak
- Biomedical and Life Sciences, Faculty of Health and Medicine, Lancaster University, Lancaster, LA1 4YG, UK.
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De Lima AR, Noris-Suárez K, Bretaña A, Contreras VT, Navarro MC, Pérez-Ybarra L, Bubis J. Growth arrest and morphological changes triggered by emodin on Trypanosoma cruzi epimastigotes cultivated in axenic medium. Biochimie 2017; 142:31-40. [PMID: 28803999 DOI: 10.1016/j.biochi.2017.08.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2016] [Accepted: 08/08/2017] [Indexed: 12/13/2022]
Abstract
Emodin is an anthraquinone obtained from Rheum palmatum rootstocks. Here we tested the cytotoxic effects of emodin on Trypanosoma cruzi epimastigotes, as well as the morphological changes that were induced by this compound in the parasite. Emodin was permeable and blocked in vitro cell division of T. cruzi epimastigotes in axenic medium, causing growth arrest in a dose-dependent but reversible manner. Emodin-exposed epimastigotes underwent duplication of organelles, such as the nucleus, kinetoplast and flagellum, but were incapable of completing cytokinesis. Neither elongation of the parasite body nor appearance of the regular longitudinal cleavage furrow was displayed, suggesting that emodin is most likely affecting components of the parasite cytoskeleton. Moreover, drug-treated parasites acquired alterations such as protuberances, folds and indentations on their membrane surface. Since emodin has been shown to be a potent protein kinase CK2 inhibitor, and we have previously described an association between tubulin and CK2 in T. cruzi epimastigotes (De Lima et al. Parasitology132, 511-523, 2006), we also measured the indirect effect of the drug on tubulin. Incubation of epimastigotes with axenic medium containing emodin hindered the endogenous phosphorylation of tubulin in whole-cell parasite extracts. All our results suggested that the parasite CK2 may be important for the maintenance of the morphology and for the regulation of mitosis-cytokinesis transition in T. cruzi epimastigotes.
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Affiliation(s)
- Ana R De Lima
- Departamento de Biología Celular, Universidad Simón Bolívar, Caracas, Venezuela; Laboratorio de Protozoología, Instituto BioMolP, Facultad de Ciencias de la Salud, Universidad de Carabobo, Valencia, Venezuela.
| | - Karem Noris-Suárez
- Departamento de Biología Celular, Universidad Simón Bolívar, Caracas, Venezuela.
| | - Antonio Bretaña
- Laboratorio de Microscopía Electrónica, Centro de Estudios Biomédicos y Veterinarios, Instituto de Estudios Científicos y Tecnológicos IDECYT, Universidad Nacional Experimental Simón Rodríguez, Caracas, Venezuela.
| | - Victor T Contreras
- Laboratorio de Protozoología, Instituto BioMolP, Facultad de Ciencias de la Salud, Universidad de Carabobo, Valencia, Venezuela.
| | - Maria C Navarro
- Laboratorio de Protozoología, Instituto BioMolP, Facultad de Ciencias de la Salud, Universidad de Carabobo, Valencia, Venezuela.
| | - Luis Pérez-Ybarra
- Departamento de Ciencias Básicas, Escuela de Bioanálisis, Universidad de Carabobo, Sede Aragua, Maracay, Venezuela.
| | - José Bubis
- Departamento de Biología Celular, Universidad Simón Bolívar, Caracas, Venezuela.
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Zacarias DA, Rolão N, de Pinho FA, Sene I, Silva JC, Pereira TC, Costa DL, Costa CHN. Causes and consequences of higher Leishmania infantum burden in patients with kala-azar: a study of 625 patients. Trop Med Int Health 2017; 22:679-687. [PMID: 28380279 DOI: 10.1111/tmi.12877] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND An infected host's Leishmania infantum load in blood is considered to be an estimate of his or her total parasite burden. Therefore, the measurement of blood parasite burden is important in the identification of factors involved in parasite control. METHODS Quantitative polymerase chain reaction was performed on blood samples from 625 patients with kala-azar consecutively admitted to a reference hospital in Teresina, Brazil. Primers were used to amplify a segment of kDNA using the TaqMan system. Non-parametric statistical tests were applied. RESULTS The median blood parasite burden was 499.2 amastigote equivalents (AE)/ml. Children <1 year old (yo) had a high parasite burden, which dropped sharply after the first year of life (192.8, AE/ml at 1 < 2 yo) and remained lower until adolescence. Following adolescence, the parasite burden increased with age, peaking among elderly individuals. Men had a higher parasite burden than women. HIV-infected patients had a much higher parasite burden than non-infected patients. The parasite burden of children under 5 years with acute moderate to severe malnourishment (weight-for-age and body mass index z-scores <-2) was almost three times greater than that of better-nourished children. The parasite burden identified in deceased patients was more than twice that of surviving patients; those with a higher risk of death, sepsis, pneumonia and jaundice also had increased parasite burdens. All of these differences were statistically significant at P-values <0.05. CONCLUSIONS These data indicate that the parasite burden in patients with kala-azar was associated with age- and gender-associated factors and with HIV infection status. Acute malnutrition could be either a cause or a consequence of a higher parasite burden. An individual's parasite burden influences his or her clinical profile, disease severity and mortality risk. The best explanation for the presence of a higher parasite burden in individuals with these immunoregulatory conditions and severe disease is the occurrence of acquired immunosuppression followed by heightened innate immunity.
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Affiliation(s)
- Danielle A Zacarias
- Laboratório de Leishmanioses, Instituto de Doenças Tropicais Natan Portella, Universidade Federal do Piauí, Teresina, Brazil
| | - Nuno Rolão
- Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa, Lisboa, Portugal
| | - Flaviane A de Pinho
- Setor de Patologia Animal, Centro de Ciências Agrárias, Universidade Federal do Piauí, Teresina, Brazil
| | - Ingridi Sene
- Laboratório de Leishmanioses, Instituto de Doenças Tropicais Natan Portella, Universidade Federal do Piauí, Teresina, Brazil
| | - Jailthon C Silva
- Laboratório de Leishmanioses, Instituto de Doenças Tropicais Natan Portella, Universidade Federal do Piauí, Teresina, Brazil
| | - Teresinha C Pereira
- Laboratório de Leishmanioses, Instituto de Doenças Tropicais Natan Portella, Universidade Federal do Piauí, Teresina, Brazil
| | - Dorcas L Costa
- Departamento Materno-Infantil, Universidade Federal do Piauí, Teresina, Brazil
| | - Carlos H N Costa
- Laboratório de Leishmanioses, Instituto de Doenças Tropicais Natan Portella, Universidade Federal do Piauí, Teresina, Brazil
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da Silva MS, Muñoz PAM, Armelin HA, Elias MC. Differences in the Detection of BrdU/EdU Incorporation Assays Alter the Calculation for G1, S, and G2 Phases of the Cell Cycle in Trypanosomatids. J Eukaryot Microbiol 2017; 64:756-770. [PMID: 28258618 DOI: 10.1111/jeu.12408] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Revised: 02/17/2017] [Accepted: 02/23/2017] [Indexed: 01/22/2023]
Abstract
Trypanosomatids are the etiologic agents of various infectious diseases in humans. They diverged early during eukaryotic evolution and have attracted attention as peculiar models for evolutionary and comparative studies. Here, we show a meticulous study comparing the incorporation and detection of the thymidine analogs BrdU and EdU in Leishmania amazonensis, Trypanosoma brucei, and Trypanosoma cruzi to monitor their DNA replication. We used BrdU- and EdU-incorporated parasites with the respective standard detection approaches: indirect immunofluorescence to detect BrdU after standard denaturation (2 M HCl) and "click" chemistry to detect EdU. We found a discrepancy between these two thymidine analogs due to the poor detection of BrdU, which is reflected on the estimative of the duration of the cell cycle phases G1, S, and G2. To solve this discrepancy, we increase the exposure of incorporated BrdU using different concentrations of HCl. Using a new value for HCl concentration, we re-estimated the phases G1, S, G2 + M, and cytokinesis durations, confirming the values found by this approach using EdU. In conclusion, we suggest that the studies using BrdU with standard detection approach, not only in trypanosomatids but also in others cell types, should be reviewed to ensure an accurate estimation of DNA replication monitoring.
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Affiliation(s)
- Marcelo Santos da Silva
- Laboratório Especial de Ciclo Celular, Center of Toxins, Immune Response and Cell Signaling (CeTICS), Butantan Institute, 1500, Vital Brasil Avenue, 05503-900, São Paulo, Brazil
| | - Paula Andrea Marin Muñoz
- Laboratório Especial de Ciclo Celular, Center of Toxins, Immune Response and Cell Signaling (CeTICS), Butantan Institute, 1500, Vital Brasil Avenue, 05503-900, São Paulo, Brazil
| | - Hugo Aguirre Armelin
- Laboratório Especial de Ciclo Celular, Center of Toxins, Immune Response and Cell Signaling (CeTICS), Butantan Institute, 1500, Vital Brasil Avenue, 05503-900, São Paulo, Brazil
| | - Maria Carolina Elias
- Laboratório Especial de Ciclo Celular, Center of Toxins, Immune Response and Cell Signaling (CeTICS), Butantan Institute, 1500, Vital Brasil Avenue, 05503-900, São Paulo, Brazil
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Sullenberger C, Piqué D, Ogata Y, Mensa-Wilmot K. AEE788 Inhibits Basal Body Assembly and Blocks DNA Replication in the African Trypanosome. Mol Pharmacol 2017; 91:482-498. [PMID: 28246189 PMCID: PMC5399642 DOI: 10.1124/mol.116.106906] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2016] [Accepted: 02/17/2017] [Indexed: 12/15/2022] Open
Abstract
Trypanosoma brucei causes human African trypanosomiasis (HAT). The pyrrolopyrimidine AEE788 (a hit for anti-HAT drug discovery) associates with three trypanosome protein kinases. Herein we delineate the effects of AEE788 on T. brucei using chemical biology strategies. AEE788 treatment inhibits DNA replication in the kinetoplast (mitochondrial nucleoid) and nucleus. In addition, AEE788 blocks duplication of the basal body and the bilobe without affecting mitosis. Thus, AEE788 prevents entry into the S-phase of the cell division cycle. To study the kinetics of early events in trypanosome division, we employed an "AEE788 block and release" protocol to stage entry into the S-phase. A time-course of DNA synthesis (nuclear and kinetoplast DNA), duplication of organelles (basal body, bilobe, kinetoplast, nucleus), and cytokinesis was obtained. Unexpected findings include the following: 1) basal body and bilobe duplication are concurrent; 2) maturation of probasal bodies, marked by TbRP2 recruitment, is coupled with nascent basal body assembly, monitored by localization of TbSAS6 at newly forming basal bodies; and 3) kinetoplast division is observed in G2 after completion of nuclear DNA synthesis. Prolonged exposure of trypanosomes to AEE788 inhibited transferrin endocytosis, altered cell morphology, and decreased cell viability. To discover putative effectors for the pleiotropic effects of AEE788, proteome-wide changes in protein phosphorylation induced by the drug were determined. Putative effectors include an SR protein kinase, bilobe proteins, TbSAS4, TbRP2, and BILBO-1. Loss of function of one or more of these effectors can, from published literature, explain the polypharmacology of AEE788 on trypanosome biology.
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Affiliation(s)
- Catherine Sullenberger
- Department of Cellular Biology, and Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia (C.S., D.P., K.M.-W.); and the Proteomics Facility, Fred Hutchinson Cancer Research Center, Seattle, Washington (Y.O.)
| | - Daniel Piqué
- Department of Cellular Biology, and Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia (C.S., D.P., K.M.-W.); and the Proteomics Facility, Fred Hutchinson Cancer Research Center, Seattle, Washington (Y.O.)
| | - Yuko Ogata
- Department of Cellular Biology, and Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia (C.S., D.P., K.M.-W.); and the Proteomics Facility, Fred Hutchinson Cancer Research Center, Seattle, Washington (Y.O.)
| | - Kojo Mensa-Wilmot
- Department of Cellular Biology, and Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia (C.S., D.P., K.M.-W.); and the Proteomics Facility, Fred Hutchinson Cancer Research Center, Seattle, Washington (Y.O.)
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30
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Ausiannikava D, Allers T. Diversity of DNA Replication in the Archaea. Genes (Basel) 2017; 8:genes8020056. [PMID: 28146124 PMCID: PMC5333045 DOI: 10.3390/genes8020056] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Accepted: 01/20/2017] [Indexed: 02/07/2023] Open
Abstract
DNA replication is arguably the most fundamental biological process. On account of their shared evolutionary ancestry, the replication machinery found in archaea is similar to that found in eukaryotes. DNA replication is initiated at origins and is highly conserved in eukaryotes, but our limited understanding of archaea has uncovered a wide diversity of replication initiation mechanisms. Archaeal origins are sequence-based, as in bacteria, but are bound by initiator proteins that share homology with the eukaryotic origin recognition complex subunit Orc1 and helicase loader Cdc6). Unlike bacteria, archaea may have multiple origins per chromosome and multiple Orc1/Cdc6 initiator proteins. There is no consensus on how these archaeal origins are recognised—some are bound by a single Orc1/Cdc6 protein while others require a multi- Orc1/Cdc6 complex. Many archaeal genomes consist of multiple parts—the main chromosome plus several megaplasmids—and in polyploid species these parts are present in multiple copies. This poses a challenge to the regulation of DNA replication. However, one archaeal species (Haloferax volcanii) can survive without replication origins; instead, it uses homologous recombination as an alternative mechanism of initiation. This diversity in DNA replication initiation is all the more remarkable for having been discovered in only three groups of archaea where in vivo studies are possible.
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Affiliation(s)
- Darya Ausiannikava
- School of Life Sciences, University of Nottingham, Nottingham NG7 2UH, UK;.
| | - Thorsten Allers
- School of Life Sciences, University of Nottingham, Nottingham NG7 2UH, UK;.
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31
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Ponce I, Aldunate C, Valenzuela L, Sepúlveda S, Garrido G, Kemmerling U, Cabrera G, Galanti N. A Flap Endonuclease (TcFEN1) Is Involved in Trypanosoma cruzi
Cell Proliferation, DNA Repair, and Parasite Survival. J Cell Biochem 2016; 118:1722-1732. [DOI: 10.1002/jcb.25830] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Accepted: 12/07/2016] [Indexed: 11/06/2022]
Affiliation(s)
- Ivan Ponce
- Programa de Biología Celular y Molecular, Instituto de Ciencias Biomédicas, Facultad de Medicina; Universidad de Chile; Santiago 8380453 Chile
| | - Carmen Aldunate
- Programa de Biología Celular y Molecular, Instituto de Ciencias Biomédicas, Facultad de Medicina; Universidad de Chile; Santiago 8380453 Chile
| | - Lucia Valenzuela
- Programa de Biología Celular y Molecular, Instituto de Ciencias Biomédicas, Facultad de Medicina; Universidad de Chile; Santiago 8380453 Chile
| | - Sofia Sepúlveda
- Programa de Biología Celular y Molecular, Instituto de Ciencias Biomédicas, Facultad de Medicina; Universidad de Chile; Santiago 8380453 Chile
| | - Gilda Garrido
- Programa de Biología Celular y Molecular, Instituto de Ciencias Biomédicas, Facultad de Medicina; Universidad de Chile; Santiago 8380453 Chile
| | - Ulrike Kemmerling
- Programa de Anatomía y Biología del Desarrollo, Instituto de Ciencias Biomédicas, Facultad de Medicina; Universidad de Chile; Santiago 8380453 Chile
| | - Gonzalo Cabrera
- Programa de Biología Celular y Molecular, Instituto de Ciencias Biomédicas, Facultad de Medicina; Universidad de Chile; Santiago 8380453 Chile
| | - Norbel Galanti
- Programa de Biología Celular y Molecular, Instituto de Ciencias Biomédicas, Facultad de Medicina; Universidad de Chile; Santiago 8380453 Chile
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32
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Uzcanga G, Lara E, Gutiérrez F, Beaty D, Beske T, Teran R, Navarro JC, Pasero P, Benítez W, Poveda A. Nuclear DNA replication and repair in parasites of the genus Leishmania: Exploiting differences to develop innovative therapeutic approaches. Crit Rev Microbiol 2016; 43:156-177. [PMID: 27960617 DOI: 10.1080/1040841x.2016.1188758] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Leishmaniasis is a common tropical disease that affects mainly poor people in underdeveloped and developing countries. This largely neglected infection is caused by Leishmania spp, a parasite from the Trypanosomatidae family. This parasitic disease has different clinical manifestations, ranging from localized cutaneous to more harmful visceral forms. The main limitations of the current treatments are their high cost, toxicity, lack of specificity, and long duration. Efforts to improve treatments are necessary to deal with this infectious disease. Many approved drugs to combat diseases as diverse as cancer, bacterial, or viral infections take advantage of specific features of the causing agent or of the disease. Recent evidence indicates that the specific characteristics of the Trypanosomatidae replication and repair machineries could be used as possible targets for the development of new treatments. Here, we review in detail the molecular mechanisms of DNA replication and repair regulation in trypanosomatids of the genus Leishmania and the drugs that could be useful against this disease.
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Affiliation(s)
- Graciela Uzcanga
- a Centro Internacional de Zoonosis, Facultad de Ciencias Químicas, Facultad de Medicina Veterinaria , Universidad Central del Ecuador , Quito , Ecuador.,b Programa Prometeo , SENESCYT, Whymper E7-37 y Alpallana, Quito , Ecuador.,c Facultad de Ciencias Naturales y Ambientales, Universidad Internacional SEK Calle Alberto Einstein sn y 5ta transversal , Quito , Ecuador.,d Fundación Instituto de Estudios Avanzados-IDEA , Caracas , Venezuela
| | - Eliana Lara
- a Centro Internacional de Zoonosis, Facultad de Ciencias Químicas, Facultad de Medicina Veterinaria , Universidad Central del Ecuador , Quito , Ecuador.,e Institute of Human Genetics , CNRS UPR 1142, 141 rue de la Cardonille, Equipe Labellisée Ligue Contre le Cancer , Montpellier cedex 5 , France
| | - Fernanda Gutiérrez
- a Centro Internacional de Zoonosis, Facultad de Ciencias Químicas, Facultad de Medicina Veterinaria , Universidad Central del Ecuador , Quito , Ecuador
| | - Doyle Beaty
- a Centro Internacional de Zoonosis, Facultad de Ciencias Químicas, Facultad de Medicina Veterinaria , Universidad Central del Ecuador , Quito , Ecuador
| | - Timo Beske
- a Centro Internacional de Zoonosis, Facultad de Ciencias Químicas, Facultad de Medicina Veterinaria , Universidad Central del Ecuador , Quito , Ecuador
| | - Rommy Teran
- a Centro Internacional de Zoonosis, Facultad de Ciencias Químicas, Facultad de Medicina Veterinaria , Universidad Central del Ecuador , Quito , Ecuador
| | - Juan-Carlos Navarro
- a Centro Internacional de Zoonosis, Facultad de Ciencias Químicas, Facultad de Medicina Veterinaria , Universidad Central del Ecuador , Quito , Ecuador.,f Universidad Central de Venezuela, Instituto de Zoología y Ecología Tropical , Caracas , Venezuela.,g Facultad de Ciencias Naturales y Ambientales, Universidad Internacional SEK, Calle Alberto Einstein sn y 5ta transversal , Quito , Ecuador
| | - Philippe Pasero
- e Institute of Human Genetics , CNRS UPR 1142, 141 rue de la Cardonille, Equipe Labellisée Ligue Contre le Cancer , Montpellier cedex 5 , France
| | - Washington Benítez
- a Centro Internacional de Zoonosis, Facultad de Ciencias Químicas, Facultad de Medicina Veterinaria , Universidad Central del Ecuador , Quito , Ecuador
| | - Ana Poveda
- a Centro Internacional de Zoonosis, Facultad de Ciencias Químicas, Facultad de Medicina Veterinaria , Universidad Central del Ecuador , Quito , Ecuador
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Liao S, Hu H, Wang T, Tu X, Li Z. The Protein Neddylation Pathway in Trypanosoma brucei: FUNCTIONAL CHARACTERIZATION AND SUBSTRATE IDENTIFICATION. J Biol Chem 2016; 292:1081-1091. [PMID: 27956554 DOI: 10.1074/jbc.m116.766741] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Revised: 11/28/2016] [Indexed: 11/06/2022] Open
Abstract
Protein posttranslational modifications such as neddylation play crucial roles in regulating protein function. Only a few neddylated substrates have been validated to date, and the role of neddylation remains poorly understood. Here, using Trypanosoma brucei as the model organism, we investigated the function and substrates of TbNedd8. TbNedd8 is distributed throughout the cytosol but enriched in the nucleus and the flagellum. Depletion of TbNedd8 by RNAi abolished global protein ubiquitination, caused DNA re-replication in postmitotic cells, impaired spindle assembly, and compromised the flagellum attachment zone filament, leading to flagellum detachment. Through affinity purification and mass spectrometry, we identified 70 TbNedd8-conjugated and -associated proteins, including known Nedd8-conjugated and -associated proteins, putative TbNedd8 conjugation system enzymes, proteins of diverse biological functions, and proteins of unknown function. Finally, we validated six Cullins as bona fide TbNedd8 substrates and identified the TbNedd8 conjugation site in three Cullins. This work lays the foundation for understanding the roles of protein neddylation in this early divergent parasitic protozoan.
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Affiliation(s)
- Shanhui Liao
- From the Hefei National Laboratory for Physical Sciences at Microscale, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230026, China and.,the Department of Microbiology and Molecular Genetics, McGovern Medical School, University of Texas Health Science Center, Houston, Texas 77030
| | - Huiqing Hu
- the Department of Microbiology and Molecular Genetics, McGovern Medical School, University of Texas Health Science Center, Houston, Texas 77030
| | - Tao Wang
- the Department of Microbiology and Molecular Genetics, McGovern Medical School, University of Texas Health Science Center, Houston, Texas 77030
| | - Xiaoming Tu
- From the Hefei National Laboratory for Physical Sciences at Microscale, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230026, China and
| | - Ziyin Li
- the Department of Microbiology and Molecular Genetics, McGovern Medical School, University of Texas Health Science Center, Houston, Texas 77030
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Thomas SM, Purmal A, Pollastri M, Mensa-Wilmot K. Discovery of a Carbazole-Derived Lead Drug for Human African Trypanosomiasis. Sci Rep 2016; 6:32083. [PMID: 27561392 PMCID: PMC5000474 DOI: 10.1038/srep32083] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2015] [Accepted: 08/02/2016] [Indexed: 02/07/2023] Open
Abstract
The protozoan parasite Trypanosoma brucei causes the fatal illness human African trypanosomiasis (HAT). Standard of care medications currently used to treat HAT have severe limitations, and there is a need to find new chemical entities that are active against infections of T. brucei. Following a "drug repurposing" approach, we tested anti-trypanosomal effects of carbazole-derived compounds called "Curaxins". In vitro screening of 26 compounds revealed 22 with nanomolar potency against axenically cultured bloodstream trypanosomes. In a murine model of HAT, oral administration of compound 1 cured the disease. These studies established 1 as a lead for development of drugs against HAT. Pharmacological time-course studies revealed the primary effect of 1 to be concurrent inhibition of mitosis coupled with aberrant licensing of S-phase entry. Consequently, polyploid trypanosomes containing 8C equivalent of DNA per nucleus and three or four kinetoplasts were produced. These effects of 1 on the trypanosome are reminiscent of "mitotic slippage" or endoreplication observed in some other eukaryotes.
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Affiliation(s)
- Sarah M Thomas
- Department of Cellular Biology, Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia 30602, USA
| | - Andrei Purmal
- Cleveland BioLabs, Inc., Buffalo, New York 14203, USA
| | - Michael Pollastri
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, Massachusetts 02115, USA
| | - Kojo Mensa-Wilmot
- Department of Cellular Biology, Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia 30602, USA
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35
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Stijlemans B, Caljon G, Van Den Abbeele J, Van Ginderachter JA, Magez S, De Trez C. Immune Evasion Strategies of Trypanosoma brucei within the Mammalian Host: Progression to Pathogenicity. Front Immunol 2016; 7:233. [PMID: 27446070 PMCID: PMC4919330 DOI: 10.3389/fimmu.2016.00233] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Accepted: 05/30/2016] [Indexed: 12/26/2022] Open
Abstract
The diseases caused by African trypanosomes (AT) are of both medical and veterinary importance and have adversely influenced the economic development of sub-Saharan Africa. Moreover, so far not a single field applicable vaccine exists, and chemotherapy is the only strategy available to treat the disease. These strictly extracellular protozoan parasites are confronted with different arms of the host's immune response (cellular as well as humoral) and via an elaborate and efficient (vector)-parasite-host interplay they have evolved efficient immune escape mechanisms to evade/manipulate the entire host immune response. This is of importance, since these parasites need to survive sufficiently long in their mammalian/vector host in order to complete their life cycle/transmission. Here, we will give an overview of the different mechanisms AT (i.e. T. brucei as a model organism) employ, comprising both tsetse fly saliva and parasite-derived components to modulate host innate immune responses thereby sculpturing an environment that allows survival and development within the mammalian host.
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Affiliation(s)
- Benoît Stijlemans
- Laboratory of Myeloid Cell Immunology, VIB Inflammation Research Center, Ghent, Belgium; Laboratory of Cellular and Molecular Immunology, Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Guy Caljon
- Laboratory for Microbiology, Parasitology and Hygiene (LMPH), University of Antwerp, Wilrijk, Belgium; Unit of Veterinary Protozoology, Department of Biomedical Sciences, Institute of Tropical Medicine Antwerp (ITM), Antwerp, Belgium
| | - Jan Van Den Abbeele
- Unit of Veterinary Protozoology, Department of Biomedical Sciences, Institute of Tropical Medicine Antwerp (ITM) , Antwerp , Belgium
| | - Jo A Van Ginderachter
- Laboratory of Myeloid Cell Immunology, VIB Inflammation Research Center, Ghent, Belgium; Laboratory of Cellular and Molecular Immunology, Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Stefan Magez
- Laboratory of Cellular and Molecular Immunology, Vrije Universiteit Brussel (VUB), Brussels, Belgium; Department of Structural Biology, VIB, Brussels, Belgium
| | - Carl De Trez
- Laboratory of Cellular and Molecular Immunology, Vrije Universiteit Brussel (VUB), Brussels, Belgium; Department of Structural Biology, VIB, Brussels, Belgium
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36
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Zhou Q, Hu H, Li Z. An EF-hand-containing Protein in Trypanosoma brucei Regulates Cytokinesis Initiation by Maintaining the Stability of the Cytokinesis Initiation Factor CIF1. J Biol Chem 2016; 291:14395-409. [PMID: 27226595 DOI: 10.1074/jbc.m116.726133] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Indexed: 11/06/2022] Open
Abstract
Trypanosoma brucei undergoes cytokinesis uni-directionally from the anterior tip of the new flagellum attachment zone (FAZ) toward the posterior end of the cell. We recently delineated a novel signaling pathway composed of polo-like kinase, cytokinesis initiation factor 1 (CIF1), and aurora B kinase that acts in concert at the new FAZ tip to regulate cytokinesis initiation. To identify new cytokinesis regulators, we carried out proximity-dependent biotin identification and identified many CIF1 binding partners and near neighbors. Here we report a novel CIF1-binding protein, named CIF2, and its mechanistic role in cytokinesis initiation. CIF2 interacts with CIF1 in vivo and co-localizes with CIF1 at the new FAZ tip during early cell cycle stages. RNAi of CIF2 inhibited the normal, anterior-to-posterior cytokinesis but activated an alternative, posterior-to-anterior cytokinesis. CIF2 depletion destabilized CIF1 and disrupted the localization of polo-like kinase and aurora B kinase to the new FAZ tip, thus revealing the mechanistic role of CIF2 in cytokinesis initiation. Surprisingly, overexpression of CIF2 also inhibited the normal, anterior-to-posterior cytokinesis and triggered the alternative, posterior-to-anterior cytokinesis, suggesting a tight control of CIF2 protein abundance. These results identified a new regulator in the cytokinesis regulatory pathway and reiterated that a backup cytokinesis pathway is activated by inhibiting the normal cytokinesis pathway.
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Affiliation(s)
- Qing Zhou
- From the Department of Microbiology and Molecular Genetics, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, Texas 77030
| | - Huiqing Hu
- From the Department of Microbiology and Molecular Genetics, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, Texas 77030
| | - Ziyin Li
- From the Department of Microbiology and Molecular Genetics, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, Texas 77030
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37
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Marques CA, Tiengwe C, Lemgruber L, Damasceno JD, Scott A, Paape D, Marcello L, McCulloch R. Diverged composition and regulation of the Trypanosoma brucei origin recognition complex that mediates DNA replication initiation. Nucleic Acids Res 2016; 44:4763-84. [PMID: 26951375 PMCID: PMC4889932 DOI: 10.1093/nar/gkw147] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Accepted: 03/01/2016] [Indexed: 01/14/2023] Open
Abstract
Initiation of DNA replication depends upon recognition of genomic sites, termed origins, by AAA+ ATPases. In prokaryotes a single factor binds each origin, whereas in eukaryotes this role is played by a six-protein origin recognition complex (ORC). Why eukaryotes evolved a multisubunit initiator, and the roles of each component, remains unclear. In Trypanosoma brucei, an ancient unicellular eukaryote, only one ORC-related initiator, TbORC1/CDC6, has been identified by sequence homology. Here we show that three TbORC1/CDC6-interacting factors also act in T. brucei nuclear DNA replication and demonstrate that TbORC1/CDC6 interacts in a high molecular complex in which a diverged Orc4 homologue and one replicative helicase subunit can also be found. Analysing the subcellular localization of four TbORC1/CDC6-interacting factors during the cell cycle reveals that one factor, TbORC1B, is not a static constituent of ORC but displays S-phase restricted nuclear localization and expression, suggesting it positively regulates replication. This work shows that ORC architecture and regulation are diverged features of DNA replication initiation in T. brucei, providing new insight into this key stage of eukaryotic genome copying.
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Affiliation(s)
- Catarina A Marques
- The Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, Sir Graeme Davis Building, 120 University Place, Glasgow, G12 8TA, UK
| | - Calvin Tiengwe
- The Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, Sir Graeme Davis Building, 120 University Place, Glasgow, G12 8TA, UK
| | - Leandro Lemgruber
- The Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, Sir Graeme Davis Building, 120 University Place, Glasgow, G12 8TA, UK
| | - Jeziel D Damasceno
- The Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, Sir Graeme Davis Building, 120 University Place, Glasgow, G12 8TA, UK
| | - Alan Scott
- The Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, Sir Graeme Davis Building, 120 University Place, Glasgow, G12 8TA, UK
| | - Daniel Paape
- The Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, Sir Graeme Davis Building, 120 University Place, Glasgow, G12 8TA, UK
| | - Lucio Marcello
- The Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, Sir Graeme Davis Building, 120 University Place, Glasgow, G12 8TA, UK
| | - Richard McCulloch
- The Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, Sir Graeme Davis Building, 120 University Place, Glasgow, G12 8TA, UK
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38
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Two distinct cytokinesis pathways drive trypanosome cell division initiation from opposite cell ends. Proc Natl Acad Sci U S A 2016; 113:3287-92. [PMID: 26929336 DOI: 10.1073/pnas.1601596113] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Cytokinesis in Trypanosoma brucei, an early branching protozoan, occurs along its longitudinal axis uni-directionally from the anterior tip of the new flagellum attachment zone filament toward the cell's posterior end. However, the underlying mechanisms remain elusive. Here we report that cytokinesis in T. brucei is regulated by a concerted action of Polo-like kinase, Aurora B kinase, and a trypanosome-specific protein CIF1. Phosphorylation of CIF1 by Polo-like kinase targets it to the anterior tip of the new flagellum attachment zone filament, where it subsequently recruits Aurora B kinase to initiate cytokinesis. Consistent with its role, CIF1 depletion inhibits cytokinesis initiation from the anterior end of the cell, but, surprisingly, triggers cytokinesis initiation from the posterior end of the cell, suggesting the activation of an alternative cytokinesis from the opposite cell end. Our results reveal the mechanistic roles of CIF1 and Polo-like kinase in cytokinesis initiation and elucidate the mechanism underlying the recruitment of Aurora B kinase to the cytokinesis initiation site at late anaphase. These findings also delineate a signaling cascade controlling cytokinesis initiation from the anterior end of the cell and uncover a backup cytokinesis that is initiated from the posterior end of the cell when the typical anterior-to-posterior cytokinesis is compromised.
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39
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Kumar G, Kajuluri LP, Gupta CM, Sahasrabuddhe AA. A twinfilin-like protein coordinates karyokinesis by influencing mitotic spindle elongation and DNA replication in Leishmania. Mol Microbiol 2016; 100:173-87. [PMID: 26713845 DOI: 10.1111/mmi.13310] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/13/2015] [Indexed: 11/30/2022]
Abstract
Twinfilin is an evolutionarily conserved actin-binding protein, which regulates actin-dynamics in eukaryotic cells. Homologs of this protein have been detected in the genome of various protozoan parasites causing diseases in human. However, very little is known about their core functions in these organisms. We show here that a twinfilin homolog in a human pathogen Leishmania, primarily localizes to the nucleolus and, to some extent, also in the basal body region. In the dividing cells, nucleolar twinfilin redistributes to the mitotic spindle and remains there partly associated with the spindle microtubules. We further show that approximately 50% depletion of this protein significantly retards the cell growth due to sluggish progression of S phase of the cell division cycle, owing to the delayed nuclear DNA synthesis. Interestingly, overexpression of this protein results in significantly increased length of the mitotic spindle in the dividing Leishmania cells, whereas, its depletion adversely affects spindle elongation and architecture. Our results indicate that twinfilin controls on one hand, the DNA synthesis and on the other, the mitotic spindle elongation, thus contributing to karyokinesis in Leishmania.
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Affiliation(s)
- Gaurav Kumar
- CSIR-Central Drug Research Institute, Jankipuram Extension-10, Sitapur Road, Lucknow, PIN-226 031, India
| | - Lova P Kajuluri
- CSIR-Central Drug Research Institute, Jankipuram Extension-10, Sitapur Road, Lucknow, PIN-226 031, India
| | - Chhitar M Gupta
- Department of Biosciences, Institute of Bioinformatics and Applied Biotechnology, Biotech Park, Electronics City, Phase-I, Bangaluru, PIN-560 100, India
| | - Amogh A Sahasrabuddhe
- CSIR-Central Drug Research Institute, Jankipuram Extension-10, Sitapur Road, Lucknow, PIN-226 031, India
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40
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Sphingosine Kinase Regulates Microtubule Dynamics and Organelle Positioning Necessary for Proper G1/S Cell Cycle Transition in Trypanosoma brucei. mBio 2015; 6:e01291-15. [PMID: 26443455 PMCID: PMC4611037 DOI: 10.1128/mbio.01291-15] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
UNLABELLED Sphingolipids are important constituents of cell membranes and also serve as mediators of cell signaling and cell recognition. Sphingolipid metabolites such as sphingosine-1-phosphate and ceramide regulate signaling cascades involved in cell proliferation and differentiation, autophagy, inflammation, and apoptosis. Little is known about how sphingolipids and their metabolites function in single-celled eukaryotes. In the present study, we investigated the role of sphingosine kinase (SPHK) in the biology of the protozoan parasite Trypanosoma brucei, the agent of African sleeping sickness. T. brucei SPHK (TbSPHK) is constitutively but differentially expressed during the life cycle of T. brucei. Depletion of TbSPHK in procyclic-form T. brucei causes impaired growth and attenuation in the G1/S phase of the cell cycle. TbSPHK-depleted cells also develop organelle positioning defects and an accumulation of tyrosinated α-tubulin at the elongated posterior end of the cell, known as the "nozzle" phenotype, caused by other molecular perturbations in this organism. Our studies indicate that TbSPHK is involved in G1-to-S cell cycle progression, organelle positioning, and maintenance of cell morphology. Cytotoxicity assays using TbSPHK inhibitors revealed a favorable therapeutic index between T. brucei and human cells, suggesting TbSPHK to be a novel drug target. IMPORTANCE Trypanosoma brucei is a single-celled parasite that is transmitted between humans and other animals by the tsetse fly. T. brucei is endemic in sub-Saharan Africa, where over 70 million people and countless livestock are at risk of developing T. brucei infection, called African sleeping sickness, resulting in economic losses of ~$35 million from the loss of cattle alone. New drugs for this infection are sorely needed and scientists are trying to identify essential enzymes in the parasite that can be targets for new therapies. One possible enzyme target is sphingosine kinase, an enzyme involved in the synthesis of lipids important for cell surface integrity and regulation of cell functions. In this study, we found that sphingosine kinase is essential for normal growth and structure of the parasite, raising the possibility that it could be a good target for new chemotherapy for sleeping sickness.
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41
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Zhou Q, Li Z. γ-Tubulin complex in Trypanosoma brucei: molecular composition, subunit interdependence and requirement for axonemal central pair protein assembly. Mol Microbiol 2015. [PMID: 26224545 DOI: 10.1111/mmi.13149] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
γ-Tubulin complex constitutes a key component of the microtubule-organizing center and nucleates microtubule assembly. This complex differs in complexity in different organisms: the budding yeast contains the γ-tubulin small complex (γTuSC) composed of γ-tubulin, gamma-tubulin complex protein (GCP)2 and GCP3, whereas animals contain the γ-tubulin ring complex (γTuRC) composed of γTuSC and three additional proteins, GCP4, GCP5 and GCP6. In Trypanosoma brucei, the composition of the γ-tubulin complex remains elusive, and it is not known whether it also regulates assembly of the subpellicular microtubules and the spindle microtubules. Here we report that the γ-tubulin complex in T. brucei is composed of γ-tubulin and three GCP proteins, GCP2-GCP4, and is primarily localized in the basal body throughout the cell cycle. Depletion of GCP2 and GCP3, but not GCP4, disrupted the axonemal central pair microtubules, but not the subpellicular microtubules and the spindle microtubules. Furthermore, we showed that the γTuSC is required for assembly of two central pair proteins and that γTuSC subunits are mutually required for stability. Together, these results identified an unusual γ-tubulin complex in T. brucei, uncovered an essential role of γTuSC in central pair protein assembly, and demonstrated the interdependence of individual γTuSC components for maintaining a stable complex.
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Affiliation(s)
- Qing Zhou
- Department of Microbiology and Molecular Genetics, University of Texas Medical School at Houston, Houston, Texas, 77030, USA
| | - Ziyin Li
- Department of Microbiology and Molecular Genetics, University of Texas Medical School at Houston, Houston, Texas, 77030, USA
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42
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Levy GV, Bañuelos CP, Níttolo AG, Ortiz GE, Mendiondo N, Moretti G, Tekiel VS, Sánchez DO. Depletion of the SR-Related Protein TbRRM1 Leads to Cell Cycle Arrest and Apoptosis-Like Death in Trypanosoma brucei. PLoS One 2015; 10:e0136070. [PMID: 26284933 PMCID: PMC4540419 DOI: 10.1371/journal.pone.0136070] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Accepted: 07/29/2015] [Indexed: 11/19/2022] Open
Abstract
Arginine-Serine (RS) domain-containing proteins are RNA binding proteins with multiple functions in RNA metabolism. In mammalian cells this group of proteins is also implicated in regulation and coordination of cell cycle and apoptosis. In trypanosomes, an early branching group within the eukaryotic lineage, this group of proteins is represented by 3 members, two of them are SR proteins and have been recently shown to be involved in rRNA processing as well as in pre-mRNA splicing and stability. Here we report our findings on the 3rd member, the SR-related protein TbRRM1. In the present study, we showed that TbRRM1 ablation by RNA-interference in T. brucei procyclic cells leads to cell-cycle block, abnormal cell elongation compatible with the nozzle phenotype and cell death by an apoptosis-like mechanism. Our results expand the role of the trypanosomal RS-domain containing proteins in key cellular processes such as cell cycle and apoptosis-like death, roles also carried out by the mammalian SR proteins, and thus suggesting a conserved function in this phylogenetically conserved protein family.
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Affiliation(s)
- Gabriela V. Levy
- Instituto de Investigaciones Biotecnológicas, Universidad Nacional de San Martín (IIB-UNSAM)—Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), 25 de Mayo y Francia. Gral. San Martín, Buenos Aires, Argentina
- * E-mail:
| | - Carolina P. Bañuelos
- Instituto de Investigaciones Biotecnológicas, Universidad Nacional de San Martín (IIB-UNSAM)—Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), 25 de Mayo y Francia. Gral. San Martín, Buenos Aires, Argentina
| | - Analía G. Níttolo
- Instituto de Investigaciones Biotecnológicas, Universidad Nacional de San Martín (IIB-UNSAM)—Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), 25 de Mayo y Francia. Gral. San Martín, Buenos Aires, Argentina
| | - Gastón E. Ortiz
- Instituto de Investigaciones Biotecnológicas, Universidad Nacional de San Martín (IIB-UNSAM)—Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), 25 de Mayo y Francia. Gral. San Martín, Buenos Aires, Argentina
| | - Nicolás Mendiondo
- Instituto de Investigaciones Biotecnológicas, Universidad Nacional de San Martín (IIB-UNSAM)—Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), 25 de Mayo y Francia. Gral. San Martín, Buenos Aires, Argentina
| | - Georgina Moretti
- Instituto de Investigaciones Biotecnológicas, Universidad Nacional de San Martín (IIB-UNSAM)—Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), 25 de Mayo y Francia. Gral. San Martín, Buenos Aires, Argentina
| | - Valeria S. Tekiel
- Instituto de Investigaciones Biotecnológicas, Universidad Nacional de San Martín (IIB-UNSAM)—Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), 25 de Mayo y Francia. Gral. San Martín, Buenos Aires, Argentina
| | - Daniel O. Sánchez
- Instituto de Investigaciones Biotecnológicas, Universidad Nacional de San Martín (IIB-UNSAM)—Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), 25 de Mayo y Francia. Gral. San Martín, Buenos Aires, Argentina
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43
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Merritt C, Silva L, Tanner AL, Stuart K, Pollastri MP. Kinases as druggable targets in trypanosomatid protozoan parasites. Chem Rev 2014; 114:11280-304. [PMID: 26443079 PMCID: PMC4254031 DOI: 10.1021/cr500197d] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Indexed: 12/21/2022]
Affiliation(s)
- Christopher Merritt
- Seattle
Biomedical Research Institute, 307 Westlake Avenue North, Suite 500, Seattle, Washington 98109-5219, United States
| | - Lisseth
E. Silva
- Department
of Chemistry & Chemical Biology, Northeastern
University, 417 Egan
Research Center, 360 Huntington Avenue, Boston, Massachusetts 02115, United States
| | - Angela L. Tanner
- Department
of Chemistry & Chemical Biology, Northeastern
University, 417 Egan
Research Center, 360 Huntington Avenue, Boston, Massachusetts 02115, United States
| | - Kenneth Stuart
- Seattle
Biomedical Research Institute, 307 Westlake Avenue North, Suite 500, Seattle, Washington 98109-5219, United States
| | - Michael P. Pollastri
- Department
of Chemistry & Chemical Biology, Northeastern
University, 417 Egan
Research Center, 360 Huntington Avenue, Boston, Massachusetts 02115, United States
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44
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Han X, Li Z. Comparative analysis of chromosome segregation in human, yeasts and trypanosome. ACTA ACUST UNITED AC 2014; 9:472-480. [PMID: 25844087 DOI: 10.1007/s11515-014-1334-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Chromosome segregation is a tightly regulated process through which duplicated genetic materials are equally partitioned into daughter cells. During the past decades, tremendous efforts have been made to understand the molecular mechanism of chromosome segregation using animals and yeasts as model systems. Recently, new insights into chromosome segregation have gradually emerged using trypanosome, an early branching parasitic protozoan, as a model organism. To uncover the unique aspects of chromosome segregation in trypanosome, which potentially could serve as new drug targets for anti-trypanosome chemotherapy, it is necessary to perform a comparative analysis of the chromosome segregation machinery between trypanosome and its human host. Here, we briefly review the current knowledge about chromosome segregation in human and Trypanosoma brucei, with a focus on the regulation of cohesin and securin degradation triggered by the activation of the anaphase promoting complex/cyclosome (APC/C). We also include yeasts in our comparative analysis since some of the original discoveries were made using budding and fission yeasts as the model organisms and, therefore, these could provide hints about the evolution of the machinery. We highlight both common and unique features in these model systems and also provide perspectives for future research in trypanosome.
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Affiliation(s)
- Xianxian Han
- Department of Microbiology and Molecular Genetics, University of Texas Medical School, Houston, TX 77030, USA
| | - Ziyin Li
- Department of Microbiology and Molecular Genetics, University of Texas Medical School, Houston, TX 77030, USA
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45
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Cavalier-Smith T. The neomuran revolution and phagotrophic origin of eukaryotes and cilia in the light of intracellular coevolution and a revised tree of life. Cold Spring Harb Perspect Biol 2014; 6:a016006. [PMID: 25183828 PMCID: PMC4142966 DOI: 10.1101/cshperspect.a016006] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Three kinds of cells exist with increasingly complex membrane-protein targeting: Unibacteria (Archaebacteria, Posibacteria) with one cytoplasmic membrane (CM); Negibacteria with a two-membrane envelope (inner CM; outer membrane [OM]); eukaryotes with a plasma membrane and topologically distinct endomembranes and peroxisomes. I combine evidence from multigene trees, palaeontology, and cell biology to show that eukaryotes and archaebacteria are sisters, forming the clade neomura that evolved ~1.2 Gy ago from a posibacterium, whose DNA segregation and cell division were destabilized by murein wall loss and rescued by the evolving novel neomuran endoskeleton, histones, cytokinesis, and glycoproteins. Phagotrophy then induced coevolving serial major changes making eukaryote cells, culminating in two dissimilar cilia via a novel gliding-fishing-swimming scenario. I transfer Chloroflexi to Posibacteria, root the universal tree between them and Heliobacteria, and argue that Negibacteria are a clade whose OM, evolving in a green posibacterium, was never lost.
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46
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Rothberg KG, Jetton N, Hubbard JG, Powell DA, Pandarinath V, Ruben L. Identification of a protein phosphatase 2A family member that regulates cell cycle progression in Trypanosoma brucei. Mol Biochem Parasitol 2014; 194:48-52. [PMID: 24780109 DOI: 10.1016/j.molbiopara.2014.04.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2013] [Revised: 04/12/2014] [Accepted: 04/18/2014] [Indexed: 11/30/2022]
Abstract
The cell cycle consists of an orderly sequence of events, whose purpose is to faithfully replicate and segregate cellular components. Many events in the cell cycle are triggered by protein kinases and counteracting phosphoprotein phosphatases (PPP). In Trypanosoma brucei, RNAi has been used to characterize numerous regulatory kinases, while the role of protein phosphatases has primarily been deduced with inhibitors such as okadaic acid and calyculin. In the present study, we identify for the first time a protein phosphatase 2A family member (TbPP2A-1) whose knockdown with RNAi phenocopies the effects of okadaic acid (OKA). In bloodstream forms (BF) and insect stage procyclic forms (PF) RNAi of TbPP2A-1 generates a cell population characterized by: an inhibition of cell growth, a block in cytokinesis; continued synthesis of nuclear DNA leading to aneuploidy; continued mitosis leading to cells with N>2, and an unusual phenotype where number of kinetoplasts (and flagella) is less than the number of nuclei. An engineered cell line was constructed to further study TbPP2A-1 and to facilitate the discovery of other cell cycle regulatory genes.
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Affiliation(s)
- Karen G Rothberg
- Department of Biological Sciences, Southern Methodist University, Dallas, TX 75275, United States
| | - Neal Jetton
- Department of Biological Sciences, Southern Methodist University, Dallas, TX 75275, United States
| | - James G Hubbard
- Department of Biological Sciences, Southern Methodist University, Dallas, TX 75275, United States
| | - Daniel A Powell
- Department of Biological Sciences, Southern Methodist University, Dallas, TX 75275, United States
| | - Vidya Pandarinath
- Department of Biological Sciences, Southern Methodist University, Dallas, TX 75275, United States
| | - Larry Ruben
- Department of Biological Sciences, Southern Methodist University, Dallas, TX 75275, United States.
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47
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PPL2 translesion polymerase is essential for the completion of chromosomal DNA replication in the African trypanosome. Mol Cell 2014; 52:554-65. [PMID: 24267450 PMCID: PMC3898837 DOI: 10.1016/j.molcel.2013.10.034] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2013] [Revised: 10/07/2013] [Accepted: 10/15/2013] [Indexed: 01/23/2023]
Abstract
Faithful copying of the genome is essential for life. In eukaryotes, a single archaeo-eukaryotic primase (AEP), DNA primase, is required for the initiation and progression of DNA replication. Here we have identified additional eukaryotic AEP-like proteins with DNA-dependent primase and/or polymerase activity. Uniquely, the genomes of trypanosomatids, a group of kinetoplastid protozoa of significant medical importance, encode two PrimPol-like (PPL) proteins. In the African trypanosome, PPL2 is a nuclear enzyme present in G2 phase cells. Following PPL2 knockdown, a cell-cycle arrest occurs after the bulk of DNA synthesis, the DNA damage response is activated, and cells fail to recover. Consistent with this phenotype, PPL2 replicates damaged DNA templates in vitro, including templates containing the UV-induced pyrimidine-pyrimidone (6-4) photoproduct. Furthermore, PPL2 accumulates at sites of nuclear DNA damage. Taken together, our results indicate an essential role for PPL2 in postreplication tolerance of endogenous DNA damage, thus allowing completion of genome duplication. Trypanosomatids contain two archaeo-eukaryotic primase-polymerase-like proteins PPL2 is essential in the pathogenic bloodstream form African trypanosome PPL2 suppresses DNA damage and allows completion of chromosomal replication PPL2 mediates translesion DNA synthesis
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48
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Abstract
Faithful transmission of genetic material is essential for the survival of all organisms. Eukaryotic chromosome segregation is driven by the kinetochore that assembles onto centromeric DNA to capture spindle microtubules and govern the movement of chromosomes. Its molecular mechanism has been actively studied in conventional model eukaryotes, such as yeasts, worms, flies and human. However, these organisms are closely related in the evolutionary time scale and it therefore remains unclear whether all eukaryotes use a similar mechanism. The evolutionary origins of the segregation apparatus also remain enigmatic. To gain insights into these questions, it is critical to perform comparative studies. Here, we review our current understanding of the mitotic mechanism in Trypanosoma brucei, an experimentally tractable kinetoplastid parasite that branched early in eukaryotic history. No canonical kinetochore component has been identified, and the design principle of kinetochores might be fundamentally different in kinetoplastids. Furthermore, these organisms do not appear to possess a functional spindle checkpoint that monitors kinetochore-microtubule attachments. With these unique features and the long evolutionary distance from other eukaryotes, understanding the mechanism of chromosome segregation in T. brucei should reveal fundamental requirements for the eukaryotic segregation machinery, and may also provide hints about the origin and evolution of the segregation apparatus.
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Affiliation(s)
- Bungo Akiyoshi
- Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, UK
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49
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Meyer KJ, Shapiro TA. Potent antitrypanosomal activities of heat shock protein 90 inhibitors in vitro and in vivo. J Infect Dis 2013; 208:489-99. [PMID: 23630365 DOI: 10.1093/infdis/jit179] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
African sleeping sickness, caused by the protozoan parasite Trypanosoma brucei, is universally fatal if untreated, and current drugs are limited by severe toxicities and difficult administration. New antitrypanosomals are greatly needed. Heat shock protein 90 (Hsp90) is a conserved and ubiquitously expressed molecular chaperone essential for stress responses and cellular signaling. We investigated Hsp90 inhibitors for their antitrypanosomal activity. Geldanamycin and radicicol had nanomolar potency in vitro against bloodstream-form T. brucei; novobiocin had micromolar activity. In structure-activity studies of geldanamycin analogs, 17-AAG and 17-DMAG were most selective against T. brucei as compared to mammalian cells. 17-AAG treatment sensitized trypanosomes to heat shock and caused severe morphological abnormalities and cell cycle disruption. Both oral and parenteral 17-DMAG cured mice of a normally lethal infection of T. brucei. These promising results support the use of inhibitors to study Hsp90 function in trypanosomes and to expand current clinical development of Hsp90 inhibitors to include T. brucei.
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Affiliation(s)
- Kirsten J Meyer
- Department of Pharmacology and Molecular Sciences, The Johns Hopkins UniversitySchool of Medicine, Baltimore, MD, USA
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Trypanosome cdc2-related kinase 9 controls spliced leader RNA cap4 methylation and phosphorylation of RNA polymerase II subunit RPB1. Mol Cell Biol 2013; 33:1965-75. [PMID: 23478263 DOI: 10.1128/mcb.00156-13] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Conserved from yeast to mammals, phosphorylation of the heptad repeat sequence Tyr(1)-Ser(2)-Pro(3)-Thr(4)-Ser(5)-Pro(6)-Ser(7) in the carboxy-terminal domain (CTD) of the largest RNA polymerase II (RNA Pol II) subunit, RPB1, mediates the enzyme's promoter escape and binding of RNA-processing factors, such as the m(7)G capping enzymes. The first critical step, Ser(5) phosphorylation, is carried out by cyclin-dependent kinase 7 (CDK7), a subunit of the basal transcription factor TFIIH. Many early-diverged protists, such as the lethal human parasite Trypanosoma brucei, however, lack the heptad repeats and, apparently, a CDK7 ortholog. Accordingly, characterization of trypanosome TFIIH did not identify a kinase component. The T. brucei CTD, however, is phosphorylated and essential for transcription. Here we show that silencing the expression of T. brucei cdc2-related kinase 9 (CRK9) leads to a loss of RPB1 phosphorylation. Surprisingly, this event did not impair RNA Pol II transcription or cotranscriptional m(7)G capping. Instead, we observed that CRK9 silencing led to a block of spliced leader (SL) trans splicing, an essential step in trypanosome mRNA maturation, that was caused by hypomethylation of the SL RNA's unique cap4.
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