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Pereira MA, Alexandre-Pires G, Câmara M, Santos M, Martins C, Rodrigues A, Adriana J, Passero LFD, Pereira da Fonseca I, Santos-Gomes G. Canine neutrophils cooperate with macrophages in the early stages of Leishmania infantum in vitro infection. Parasite Immunol 2019; 41:e12617. [PMID: 30735568 DOI: 10.1111/pim.12617] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Accepted: 01/31/2019] [Indexed: 11/28/2022]
Abstract
Leishmania infantum is the aetiological agent of human visceral leishmaniasis and canine leishmaniasis, both systemic and potentially fatal diseases. Polymorphonuclear neutrophils (PMN) are the first cells to phagocyte this parasite at the inoculation site, but macrophages (MØ) are the definitive host cells, ensuring parasite replication. The interaction between dog MØ, PMN and L infantum promastigotes was in vitro investigated. It was observed that promastigotes establish contact with blood monocyte-derived MØ mainly by the tip of the flagellum. These cells, that efficiently bind and internalize parasites, underwent major morphological changes, produced nitric oxide (NO) and released histone H1 in order to inactivate the parasite. Transfer of intracellular parasites from PMN to MØ was confirmed by flow cytometry, using L infantum expressing a green fluorescent protein. The interaction of MØ with L infantum-infected PMN lead to NO production and release of extracellular traps, which may contribute to parasite containment and inactivation. This study highlights for the first time the diversity of cellular and molecular events triggered by the interaction between canine PMN and MØ, which can promote a reduction of parasite burden in the early phase of L infantum infection.
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Affiliation(s)
- Maria A Pereira
- Global Health and Tropical Medicine (GHTM), Instituto de Higiene e Medicina Tropical (IHMT), Universidade Nova de Lisboa (UNL), Lisboa, Portugal.,Instituto Politécnico de Portalegre (IPP), Portalegre, Portugal
| | - Graça Alexandre-Pires
- Centro Interdisciplinar de Investigação em Sanidade Animal (CIISA), Faculdade de Medicina Veterinária (FMV), Universidade de Lisboa (UL), Lisboa, Portugal
| | - Margarida Câmara
- Câmara Municipal de Évora, Serviço Veterinário Municipal, Évora, Portugal
| | - Marcos Santos
- Centro Interdisciplinar de Investigação em Sanidade Animal (CIISA), Faculdade de Medicina Veterinária (FMV), Universidade de Lisboa (UL), Lisboa, Portugal
| | - Catarina Martins
- CEDOC-Chronic Diseases Research Center, Immunology, NOVA Medical School, Universidade Nova de Lisboa, Lisboa, Portugal
| | - Armanda Rodrigues
- Global Health and Tropical Medicine (GHTM), Instituto de Higiene e Medicina Tropical (IHMT), Universidade Nova de Lisboa (UNL), Lisboa, Portugal
| | - Jéssica Adriana
- Laboratory of Pathology of Infectious Diseases (LIM50), Department of Pathology, Medical School of São Paulo University, São Paulo, Brazil
| | - Luiz Felipe D Passero
- São Paulo State University (UNESP), Institute of Biosciences, São Paulo, Brazil.,São Paulo State University (UNESP), Institute for Advanced Studies of Ocean, São Paulo, Brazil
| | - Isabel Pereira da Fonseca
- Centro Interdisciplinar de Investigação em Sanidade Animal (CIISA), Faculdade de Medicina Veterinária (FMV), Universidade de Lisboa (UL), Lisboa, Portugal
| | - Gabriela Santos-Gomes
- Global Health and Tropical Medicine (GHTM), Instituto de Higiene e Medicina Tropical (IHMT), Universidade Nova de Lisboa (UNL), Lisboa, Portugal
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Nucleolar Division in the Promastigote Stage of Leishmania major Parasite: A Nop56 Point of View. BIOMED RESEARCH INTERNATIONAL 2018; 2018:1641839. [PMID: 30406129 PMCID: PMC6199852 DOI: 10.1155/2018/1641839] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Revised: 08/14/2018] [Accepted: 09/13/2018] [Indexed: 11/23/2022]
Abstract
Nucleogenesis is the cellular event responsible for the formation of the new nucleoli at the end of mitosis. This process depends on the synthesis and processing of ribosomal RNA (rRNA) and, in some eukaryotes, the transfer of nucleolar material contained in prenucleolar bodies (PNBs) to active transcription sites. The lack of a comprehensive description of the nucleolus throughout the cell cycle of the human pathogen Leishmania major prompted us to analyze the distribution of nucleolar protein 56 (Nop56) during interphase and mitosis in the promastigote stage of the parasite. By in silico analysis we show that the orthologue of Nop56 in L. major (LmNop56) contains the three characteristic Nop56 domains and that its predicted three-dimensional structure is also conserved. Fluorescence microscopy observations indicate that the nucleolar localization of LmNop56 is similar, but not identical, to that of the nucleolar protein Elp3b. Notably, unlike other nucleolar proteins, LmNop56 remains associated with the nucleolus in nonproliferative cells. Moreover, epifluorescent images indicate the preservation of the nucleolar structure throughout the closed nuclear division. Experiments performed with the related parasite Trypanosoma brucei show that nucleolar division is carried out by an analogous mechanism.
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Staneva D, Georgieva M, Miloshev G. Kluyveromyces lactis genome harbours a functional linker histone encoding gene. FEMS Yeast Res 2016; 16:fow034. [PMID: 27189369 DOI: 10.1093/femsyr/fow034] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/02/2016] [Indexed: 11/14/2022] Open
Abstract
Linker histones are essential components of chromatin in eukaryotes. Through interactions with linker DNA and nucleosomes they facilitate folding and maintenance of higher-order chromatin structures and thus delicately modulate gene activity. The necessity of linker histones in lower eukaryotes appears controversial and dubious. Genomic data have shown that Schizosaccharomyces pombe does not possess genes encoding linker histones while Kluyveromyces lactis has been reported to have a pseudogene. Regarding this controversy, we have provided the first direct experimental evidence for the existence of a functional linker histone gene, KlLH1, in K. lactis genome. Sequencing of KlLH1 from both genomic DNA and copy DNA confirmed the presence of an intact open reading frame. Transcription and splicing of the KlLH1 sequence as well as translation of its mRNA have been studied. In silico analysis revealed homology of KlLH1p to the histone H1/H5 protein family with predicted three domain structure characteristic for the linker histones of higher eukaryotes. This strongly proves that the yeast K. lactis does indeed possess a functional linker histone gene thus entailing the evolutionary preservation and significance of linker histones. The nucleotide sequences of KlLH1 are deposited in the GenBank under accession numbers KT826576, KT826577 and KT826578.
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Affiliation(s)
- Dessislava Staneva
- Laboratory of Yeast Molecular Genetics, Institute of Molecular Biology, Bulgarian Academy of Sciences, 'Acad. Roumen Tsanev', Sofia 1113, Bulgaria
| | - Milena Georgieva
- Laboratory of Yeast Molecular Genetics, Institute of Molecular Biology, Bulgarian Academy of Sciences, 'Acad. Roumen Tsanev', Sofia 1113, Bulgaria
| | - George Miloshev
- Laboratory of Yeast Molecular Genetics, Institute of Molecular Biology, Bulgarian Academy of Sciences, 'Acad. Roumen Tsanev', Sofia 1113, Bulgaria
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Pena AC, Pimentel MR, Manso H, Vaz-Drago R, Pinto-Neves D, Aresta-Branco F, Rijo-Ferreira F, Guegan F, Pedro Coelho L, Carmo-Fonseca M, Barbosa-Morais NL, Figueiredo LM. Trypanosoma brucei histone H1 inhibits RNA polymerase I transcription and is important for parasite fitness in vivo. Mol Microbiol 2014; 93:645-63. [PMID: 24946224 PMCID: PMC4285223 DOI: 10.1111/mmi.12677] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/15/2014] [Indexed: 11/30/2022]
Abstract
Trypanosoma brucei is a unicellular parasite that causes sleeping sickness in humans. Most of its transcription is constitutive and driven by RNA polymerase II. RNA polymerase I (Pol I) transcribes not only ribosomal RNA genes, but also protein-encoding genes, including variant surface glycoproteins (VSGs) and procyclins. In T. brucei, histone H1 (H1) is required for VSG silencing and chromatin condensation. However, whether H1 has a genome-wide role in transcription is unknown. Here, using RNA sequencing we show that H1 depletion changes the expression of a specific cohort of genes. Interestingly, the predominant effect is partial loss of silencing of Pol I loci, such as VSG and procyclin genes. Labelling of nascent transcripts with 4-thiouridine showed that H1 depletion does not alter the level of labelled Pol II transcripts. In contrast, the levels of 4sU-labelled Pol I transcripts were increased by two- to sixfold, suggesting that H1 preferentially blocks transcription at Pol I loci. Finally, we observed that parasites depleted of H1 grow almost normally in culture but they have a reduced fitness in mice, suggesting that H1 is important for host-pathogen interactions.
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Affiliation(s)
- Ana C Pena
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Av. Prof. Egas Moniz, Edifício Egas Moniz, 1649-028, Lisboa, Portugal
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Alexandratos A, Clos J, Samiotaki M, Efstathiou A, Panayotou G, Soteriadou K, Smirlis D. The loss of virulence of histone H1 overexpressingLeishmania donovaniparasites is directly associated with a reduction of HSP83 rate of translation. Mol Microbiol 2013; 88:1015-31. [DOI: 10.1111/mmi.12240] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/15/2013] [Indexed: 01/15/2023]
Affiliation(s)
- Alexandros Alexandratos
- Laboratory of Molecular Parasitology; Department of Microbiology; Hellenic Pasteur Institute; 127 Vas Sofias Ave. Athens Greece
- Chemistry Department; University of Ioannina; Ioannina Greece
| | - Joachim Clos
- Bernhard Nocht Institute for Tropical Medicine; Hamburg Germany
| | - Martina Samiotaki
- Biomedical Sciences Research Center; ‘Alexander Fleming’; Vari Greece
| | - Antonia Efstathiou
- Laboratory of Molecular Parasitology; Department of Microbiology; Hellenic Pasteur Institute; 127 Vas Sofias Ave. Athens Greece
| | - George Panayotou
- Biomedical Sciences Research Center; ‘Alexander Fleming’; Vari Greece
| | - Ketty Soteriadou
- Laboratory of Molecular Parasitology; Department of Microbiology; Hellenic Pasteur Institute; 127 Vas Sofias Ave. Athens Greece
| | - Despina Smirlis
- Laboratory of Molecular Parasitology; Department of Microbiology; Hellenic Pasteur Institute; 127 Vas Sofias Ave. Athens Greece
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Povelones ML, Gluenz E, Dembek M, Gull K, Rudenko G. Histone H1 plays a role in heterochromatin formation and VSG expression site silencing in Trypanosoma brucei. PLoS Pathog 2012; 8:e1003010. [PMID: 23133390 PMCID: PMC3486875 DOI: 10.1371/journal.ppat.1003010] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2012] [Accepted: 09/20/2012] [Indexed: 11/30/2022] Open
Abstract
The African sleeping sickness parasite Trypanosoma brucei evades the host immune system through antigenic variation of its variant surface glycoprotein (VSG) coat. Although the T. brucei genome contains ∼1500 VSGs, only one VSG is expressed at a time from one of about 15 subtelomeric VSG expression sites (ESs). For antigenic variation to work, not only must the vast VSG repertoire be kept silent in a genome that is mainly constitutively transcribed, but the frequency of VSG switching must be strictly controlled. Recently it has become clear that chromatin plays a key role in silencing inactive ESs, thereby ensuring monoallelic expression of VSG. We investigated the role of the linker histone H1 in chromatin organization and ES regulation in T. brucei. T. brucei histone H1 proteins have a different domain structure to H1 proteins in higher eukaryotes. However, we show that they play a key role in the maintenance of higher order chromatin structure in bloodstream form T. brucei as visualised by electron microscopy. In addition, depletion of histone H1 results in chromatin becoming generally more accessible to endonucleases in bloodstream but not in insect form T. brucei. The effect on chromatin following H1 knock-down in bloodstream form T. brucei is particularly evident at transcriptionally silent ES promoters, leading to 6–8 fold derepression of these promoters. T. brucei histone H1 therefore appears to be important for the maintenance of repressed chromatin in bloodstream form T. brucei. In particular H1 plays a role in downregulating silent ESs, arguing that H1-mediated chromatin functions in antigenic variation in T. brucei. Trypanosoma brucei causes African sleeping sickness, endemic to sub-Saharan Africa. Bloodstream form T. brucei is covered with a dense coat of variant surface glycoprotein (VSG). Only one VSG is expressed at a time out of a vast repertoire of ∼1500 VSGs. The active VSG is transcribed in a telomeric VSG expression site (ES), and VSG switching allows immune evasion. Exactly how monoallelic exclusion of VSG ESs operates, and how switching between ESs is mediated remains mysterious, although epigenetics and chromatin structure clearly play a major role. The linker histone H1 is thought to orchestrate higher order chromatin structure in eukaryotes, but its exact function is unclear. We investigated the role of histone H1 in the regulation of antigenic variation in T. brucei. We show that histone H1 is associated with chromatin and is required for higher order chromatin structure. Depletion of histone H1 results in derepression of silent VSG ES promoters, indicating that H1-mediated chromatin functions in antigenic variation in T. brucei.
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Affiliation(s)
- Megan L. Povelones
- Division of Cell and Molecular Biology, Imperial College London, South Kensington, London, United Kingdom
| | - Eva Gluenz
- The Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Marcin Dembek
- Division of Cell and Molecular Biology, Imperial College London, South Kensington, London, United Kingdom
| | - Keith Gull
- The Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Gloria Rudenko
- Division of Cell and Molecular Biology, Imperial College London, South Kensington, London, United Kingdom
- * E-mail:
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7
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Characterization of monomeric DNA-binding protein Histone H1 in Leishmania braziliensis. Parasitology 2011; 138:1093-101. [PMID: 21767437 DOI: 10.1017/s0031182011000898] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Histone H1 in Leishmania presents relevant differences compared to higher eukaryote counterparts, such as the lack of a DNA-binding central globular domain. Despite that, it is apparently fully functional since its differential expression levels have been related to changes in chromatin condensation and infectivity, among other features. The localization and the aggregation state of L. braziliensis H1 has been determined by immunolocalization, mass spectrometry, cross-linking and electrophoretic mobility shift assays. Analysis of H1 sequences from the Leishmania Genome Database revealed that our protein is included in a very divergent group of histones H1 that is present only in L. braziliensis. An antibody raised against recombinant L. braziliensis H1 recognized specifically that protein by immunoblot in L. braziliensis extracts, but not in other Leishmania species, a consequence of the sequence divergences observed among Leishmania species. Mass spectrometry analysis and in vitro DNA-binding experiments have also proven that L. braziliensis H1 is monomeric in solution, but oligomerizes upon binding to DNA. Finally, despite the lack of a globular domain, L. braziliensis H1 is able to form complexes with DNA in vitro, with higher affinity for supercoiled compared to linear DNA.
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8
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Kelly BL, Singh G, Aiyar A. Molecular and cellular characterization of an AT-hook protein from Leishmania. PLoS One 2011; 6:e21412. [PMID: 21731738 PMCID: PMC3121789 DOI: 10.1371/journal.pone.0021412] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2011] [Accepted: 05/27/2011] [Indexed: 11/26/2022] Open
Abstract
AT-rich DNA, and the proteins that bind it (AT-hook proteins), modulate chromosome structure and function in most eukaryotes. Unlike other trypanosomatids, the genome of Leishmania species is unusually GC-rich, and the regulation of Leishmania chromosome structure, replication, partitioning is not fully understood. Because AT-hook proteins modulate these functions in other eukaryotes, we examined whether AT-hook proteins are encoded in the Leishmania genome, to test their potential functions. Several Leishmania ORFs predicted to be AT-hook proteins were identified using in silico approaches based on sequences shared between eukaryotic AT-hook proteins. We have used biochemical, molecular and cellular techniques to characterize the L. amazonensis ortholog of the L. major protein LmjF06.0720, a potential AT-hook protein that is highly conserved in Leishmania species. Using a novel fusion between the AT-hook domain encoded by LmjF06.0720 and a herpesviral protein, we have demonstrated that LmjF06.0720 functions as an AT-hook protein in mammalian cells. Further, as observed for mammalian and viral AT-hook proteins, the AT-hook domains of LmjF06.0720 bind specific regions of condensed mammalian metaphase chromosomes, and support the licensed replication of DNA in mammalian cells. LmjF06.0720 is nuclear in Leishmania, and this localization is disrupted upon exposure to drugs that displace AT-hook proteins from AT-rich DNA. Coincidentally, these drugs dramatically alter the cellular physiology of Leishmania promastigotes. Finally, we have devised a novel peptido-mimetic agent derived from the sequence of LmjF06.0720 that blocks the proliferation of Leishmania promastigotes, and lowers amastigote parasitic burden in infected macrophages. Our results indicate that AT-hook proteins are critical for the normal biology of Leishmania. In addition, we have described a simple technique to examine the function of Leishmania chromatin-binding proteins in a eukaryotic context amenable to studying chromosome structure and function. Lastly, we demonstrate the therapeutic potential of compounds directed against AT-hook proteins in Leishmania.
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Affiliation(s)
- Ben L. Kelly
- Department of Microbiology, Immunology and Parasitology, Lousiana State University Health Sciences Center, New Orleans, Louisiana, United States of America
| | - Gyanendra Singh
- Stanley S. Scott Cancer Center, Lousiana State University Health Sciences Center, New Orleans, Louisiana, United States of America
| | - Ashok Aiyar
- Department of Microbiology, Immunology and Parasitology, Lousiana State University Health Sciences Center, New Orleans, Louisiana, United States of America
- Stanley S. Scott Cancer Center, Lousiana State University Health Sciences Center, New Orleans, Louisiana, United States of America
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Singh R, Kumar D, Duncan RC, Nakhasi HL, Salotra P. Overexpression of histone H2A modulates drug susceptibility in Leishmania parasites. Int J Antimicrob Agents 2010; 36:50-7. [DOI: 10.1016/j.ijantimicag.2010.03.012] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2009] [Revised: 01/22/2010] [Accepted: 03/03/2010] [Indexed: 12/01/2022]
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10
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Gene expression in trypanosomatid parasites. J Biomed Biotechnol 2010; 2010:525241. [PMID: 20169133 PMCID: PMC2821653 DOI: 10.1155/2010/525241] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2009] [Accepted: 11/04/2009] [Indexed: 12/21/2022] Open
Abstract
The parasites Leishmania spp., Trypanosoma brucei, and Trypanosoma cruzi are the trypanosomatid protozoa that cause the deadly human diseases leishmaniasis, African sleeping sickness, and Chagas disease, respectively. These organisms possess unique mechanisms for gene expression such as constitutive polycistronic transcription of protein-coding genes and trans-splicing. Little is known about either the DNA sequences or the proteins that are involved in the initiation and termination of transcription in trypanosomatids. In silico analyses of the genome databases of these parasites led to the identification of a small number of proteins involved in gene expression. However, functional studies have revealed that trypanosomatids have more general transcription factors than originally estimated. Many posttranslational histone modifications, histone variants, and chromatin modifying enzymes have been identified in trypanosomatids, and recent genome-wide studies showed that epigenetic regulation might play a very important role in gene expression in this group of parasites. Here, we review and comment on the most recent findings related to transcription initiation and termination in trypanosomatid protozoa.
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Thomas S, Green A, Sturm NR, Campbell DA, Myler PJ. Histone acetylations mark origins of polycistronic transcription in Leishmania major. BMC Genomics 2009; 10:152. [PMID: 19356248 PMCID: PMC2679053 DOI: 10.1186/1471-2164-10-152] [Citation(s) in RCA: 100] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2008] [Accepted: 04/08/2009] [Indexed: 11/19/2022] Open
Abstract
Background Many components of the RNA polymerase II transcription machinery have been identified in kinetoplastid protozoa, but they diverge substantially from other eukaryotes. Furthermore, protein-coding genes in these organisms lack individual transcriptional regulation, since they are transcribed as long polycistronic units. The transcription initiation sites are assumed to lie within the 'divergent strand-switch' regions at the junction between opposing polycistronic gene clusters. However, the mechanism by which Kinetoplastidae initiate transcription is unclear, and promoter sequences are undefined. Results The chromosomal location of TATA-binding protein (TBP or TRF4), Small Nuclear Activating Protein complex (SNAP50), and H3 histones were assessed in Leishmania major using microarrays hybridized with DNA obtained through chromatin immunoprecipitation (ChIP-chip). The TBP and SNAP50 binding patterns were almost identical and high intensity peaks were associated with tRNAs and snRNAs. Only 184 peaks of acetylated H3 histone were found in the entire genome, with substantially higher intensity in rapidly-dividing cells than stationary-phase. The majority of the acetylated H3 peaks were found at divergent strand-switch regions, but some occurred at chromosome ends and within polycistronic gene clusters. Almost all these peaks were associated with lower intensity peaks of TBP/SNAP50 binding a few kilobases upstream, evidence that they represent transcription initiation sites. Conclusion The first genome-wide maps of DNA-binding protein occupancy in a kinetoplastid organism suggest that H3 histones at the origins of polycistronic transcription of protein-coding genes are acetylated. Global regulation of transcription initiation may be achieved by modifying the acetylation state of these origins.
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Affiliation(s)
- Sean Thomas
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA.
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12
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Leishmania amazonensis promastigotes induce and are killed by neutrophil extracellular traps. Proc Natl Acad Sci U S A 2009; 106:6748-53. [PMID: 19346483 DOI: 10.1073/pnas.0900226106] [Citation(s) in RCA: 405] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Neutrophils are short-lived leukocytes that die by apoptosis, necrosis, and NETosis. Upon death by NETosis, neutrophils release fibrous traps of DNA, histones, and granule proteins named neutrophil extracellular traps (NETs), which can kill bacteria and fungi. Inoculation of the protozoan Leishmania into the mammalian skin causes local inflammation with neutrophil recruitment. Here, we investigated the release of NETs by human neutrophils upon their interaction with Leishmania parasites and NETs' ability to kill this protozoan. The NET constituents DNA, elastase, and histones were detected in traps associated to promastigotes by immunofluorescence. Electron microscopy revealed that Leishmania was ensnared by NETs released by neutrophils. Moreover, Leishmania and its surface lipophosphoglycan induced NET release by neutrophils in a parasite number- and dose-dependent manner. Disruption of NETs by DNase treatment during Leishmania-neutrophil interaction increased parasite survival, evidencing NETs' leishmanicidal effect. Leishmania killing was also elicited by NET-rich supernatants from phorbol 12-myristate 13-acetate-activated neutrophils. Immunoneutralization of histone during Leishmania-neutrophil interaction partially reverted Leishmania killing, and purified histone killed the parasites. Meshes composed of DNA and elastase were evidenced in biopsies of human cutaneous leishmaniasis. NET is an innate response that might contribute to diminish parasite burden in the Leishmania inoculation site.
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Histone H1 of Trypanosoma cruzi is concentrated in the nucleolus region and disperses upon phosphorylation during progression to mitosis. EUKARYOTIC CELL 2008; 7:560-8. [PMID: 18281601 DOI: 10.1128/ec.00460-07] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Phosphorylation of histone H1 is intimately related to the cell cycle progression in higher eukaryotes, reaching maximum levels during mitosis. We have previously shown that in the flagellated protozoan Trypanosoma cruzi, which does not condense chromatin during mitosis, histone H1 is phosphorylated at a single cyclin-dependent kinase site. By using an antibody that recognizes specifically the phosphorylated T. cruzi histone H1 site, we have now confirmed that T. cruzi histone H1 is also phosphorylated in a cell cycle-dependent manner. Differently from core histones, the bulk of nonphosphorylated histone H1 in G(1) and S phases of the cell cycle is concentrated in the central regions of the nucleus, which contains the nucleolus and less densely packed chromatin. When cells pass G(2), histone H1 becomes phosphorylated and starts to diffuse. At the onset of mitosis, histone H1 phosphorylation is maximal and found in the entire nuclear space. As permeabilized parasites preferentially lose phosphorylated histone H1, we conclude that this modification promotes its release from less condensed and nucleolar chromatin after G(2).
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