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Sent on Thursday, 2011 Oct 06Search kinetoplastids OR kinetoplastid OR Kinetoplastida OR "trypanosoma brucei" OR leishmania OR brucei OR leishmaniasis OR "African trypanosomiasis"
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| PubMed Results |
| 1. | Virulence. 2011 Nov 1;2(6). [Epub ahead of print]Muco-cutaneous leishmaniasis in the New World: The ultimate subversion.Ronet C, Beverley SM, Fasel N.SourceDepartment of Biochemistry; University of Lausanne; Epalinges, Switzerland. AbstractInfection by the human protozoan parasite Leishmania can lead, depending primarily on the parasite species, to either cutaneous or mucocutaneous lesions, or fatal generalized visceral infection. In the New World, Leishmania (Viannia) species can cause mucocutaneous leishmaniasis (MCL). Clinical MCL involves a strong hyper-inflammatory response and parasitic dissemination (metastasis) from a primary lesion to distant sites, leading to destructive metastatic secondary lesions especially in the nasopharyngal areas. Recently, we reported that metastasizing, but not non-metastatic strains of Leishmania (Viannia) guyanensis, have high burden of a non-segmented dsRNA virus, Leishmania RNA Virus (LRV). Viral dsRNA is sensed by the host Toll-like Receptor 3 (TLR3) thereby inducing a pro-inflammatory response and exacerbating the disease. The presence of LRV in Leishmania opens new perspectives not only in basic understanding of the intimate relation between the parasite and LRV, but also in understanding the importance of the inflammatory response in MCL patients. |
| 2. | Mol Biochem Parasitol. 2011 Sep 29. [Epub ahead of print]Development of an efficient in vitro transcription system for bloodstream form Trypanosoma brucei reveals life cycle-independent functionality of class I transcription factor A.Park SH, Nguyen TN, Günzl A.SourceDepartment of Genetics and Developmental Biology, University of Connecticut Health Center, 400 Farmington Avenue, Farmington, CT 06030-6403, USA. AbstractTrypanosomatid parasites possess extremely divergent transcription factors whose identification typically relied on biochemical, structural and functional analyses because they could not be identified by standard sequence analysis. For example, subunits of the Trypanosoma brucei mediator and class I transcription factor A (CITFA) have no sequence resemblance to putative counterparts in higher eukaryotes. Therefore, homologous in vitro transcription systems have been crucial in evaluating the transcriptional roles of T. brucei proteins but so far such systems have been restricted to the insect-stage, procyclic form (PF) of the parasite. Here, we report the development of a homologous system for the mammalian-infective, bloodstream form (BF) of T. brucei which supports accurately initiated transcription from three different RNA polymerase (pol) I promoters as well as from the RNA pol II-recruiting spliced leader RNA gene promoter. The system is based on a small scale extract preparation procedure which accommodates the low cell densities obtainable in BF culture. BF and PF systems behave surprisingly similar and we show that the CITFA complex purified from procyclic extract is fully functional in the BF system indicating that the transcriptional machinery in general is equivalent in both life cycle stages. A notable difference, however, was observed with the RNA pol I-recruiting GPEET procyclin promoter whose reduced promoter strength and increased sensitivity to manganese ions in the BF system suggests the specific presence of a transcriptional activator in the PF system. Copyright © 2011. Published by Elsevier B.V. |
| 3. | Int J Parasitol. 2011 Oct;41(12):1273-83. Epub 2011 Aug 26.The characterization and evolutionary relationships of a trypanosomal thiolase.Mazet M , Harijan RK, Kiema TR, Haapalainen AM, Morand P, Morales J, Bringaud F, Wierenga RK, Michels PA.SourceResearch Unit for Tropical Diseases, de Duve Institute and Laboratory of Biochemistry, Université catholique de Louvain, TROP 74.39, Avenue Hippocrate 74, B-1200 Brussels, Belgium. AbstractThiolases are enzymes that remove an acetyl-coenzyme A group from acyl-CoA in the catabolic β-oxidation of fatty acids, or catalyse the reverse condensation reaction for anabolic processes such as the biosynthesis of sterols and ketone bodies. In humans, six homologous isoforms of thiolase have been described, differing from each other in sequence, oligomeric state, substrate specificity and subcellular localization. A bioinformatics analysis of parasite genomes, being (i) different species of African trypanosomes, (ii) Trypanosoma cruzi and (iii) Leishmania spp., using the six human sequences as queries, showed that the distribution of thiolases in human and each of the studied Trypanosomatidae is completely different. Only one of these isoforms, called SCP2-thiolase, was found in each of the Trypanosomatidae, whereas the TFE-thiolase was also found in T. cruzi and Leishmania spp., and the AB-thiolase only in T. cruzi. Each of the trypanosomatid thiolases clusters with its orthologues from other organisms in a phylogenetic analysis and shares with them the isoform-specific sequence fingerprints. The single T. brucei SCP2-thiolase has been expressed in Escherichia coli and characterized. It shows activity in both the degradative and synthetic directions. Transcripts of this thiolase were detected in both bloodstream- and procyclic-form trypanosomes, but the protein was found only in the procyclic form. The encoded protein has both a predicted N-terminal mitochondrial signal peptide and a C-terminal candidate type 1 peroxisomal-targeting signal for sorting it into glycosomes. However experimentally, only a mitochondrial localization was found for both procyclic trypanosomes grown with glucose and cells cultured with amino acids as an energy source. When the thiolase expression in procyclic cells was knocked down by RNA interference, no important change in growth rate occurred, irrespective of whether the cells were grown with or without glucose, indicating that the metabolic pathway(s) involving this enzyme is/are not essential for the parasite under either of these growth conditions. Copyright © 2011 Australian Society for Parasitology Inc. Published by Elsevier Ltd. All rights reserved. |
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| 4. | Parasit Vectors. 2011 Aug 26;4:166.Identification of the HSP70-II gene in Leishmania braziliensis HSP70 locus: genomic organization and UTRs characterization.Ramírez CA, Requena JM, Puerta CJ.SourceLaboratorio de Parasitología Molecular, Departamento de Microbiología, Facultad de Ciencias, Pontificia Universidad Javeriana, Carrera 7 No, 43-82, Edificio 52, Oficina 608, Bogotá, Colombia. cpuerta@javeriana.edu.co. AbstractABSTRACT: BACKGROUND:The heat stress suffered by Leishmania sp during its digenetic life-cycle is a key trigger for its stage differentiation. In Leishmania subgenera two classes of HSP70 genes differing in their 3' UTR were described. Although the presence of HSP70-I genes was previously suggested in Leishmania (Viannia) braziliensis, HSP70-II genes had been reluctant to be uncovered. RESULTS:Here, we report the existence of two types of HSP70 genes in L. braziliensis and the genomic organization of the HSP70 locus. RT-PCR experiments were used to map the untranslated regions (UTR) of both types of genes. The 3' UTR-II has a low sequence identity (55-57%) when compared with this region in other Leishmania species. In contrast, the 5' UTR, common to both types of genes, and the 3' UTR-I were found to be highly conserved among all Leishmania species (77-81%). Southern blot assays suggested that L. braziliensis HSP70 gene cluster may contain around 6 tandemly-repeated HSP70-I genes followed by one HSP70-II gene, located at chromosome 28. Northern blot analysis indicated that levels of both types of mRNAs are not affected by heat shock. CONCLUSIONS:This study has led to establishing the composition and structure of the HSP70 locus of L. braziliensis, complementing the information available in the GeneDB genome database for this species. L. braziliensis HSP70 gene regulation does not seem to operate by mRNA stabilization as occurs in other Leishmania species. |
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| 5. | Photomed Laser Surg. 2011 Oct;29(10):711-5. Epub 2011 Jun 14.Photodynamic therapy using methylene blue to treat cutaneous leishmaniasis.Song D, Lindoso JA, Oyafuso LK, Kanashiro EH, Cardoso JL, Uchoa AF, Tardivo JP, Baptista MS.Source1 Departamento de Bioquímica-Instituto de Química, Universidade de São Paulo , São Paulo-SP, Brazil . AbstractAbstract Objective: The purpose of this study was to show the efficiency and underlying mechanism of action of photodynamic therapy (PDT) using methylene blue (MB) and non-coherent light sources to treat cutaneous leishmaniasis (CL). Background data: Systemic treatment can cause severe side effects, and PDT using porphyrin precursors as sensitizers has been used as an alternative to treat CL. MB has been used under illumination or in the dark to treat a wide range of medical conditions, and it exhibits antimicrobial activity against protozoa and viruses. Methods: In in vitro tests, the cell viability (via a MTT colorimetric assay) of Leishmania amazonensis parasites was evaluated as a function of MB concentration. In in vivo experiments, we analyzed the treatment of two lesions from a patient with leishmaniasis. The patient received a low dose of pentavalent antimony (SbV), and one lesion was treated with PDT. Results: We observed IC(50) decreases from 100 to 20 μM in response to PDT when MB was used in different concentrations in in vitro tests. Use of SbV in combination with the PDT protocol produced faster wound recovery when compared with the use of SbV alone. Conclusions: The in vitro experiments and the results from the clinical case suggest that the inexpensive PDT protocol that is based on MB and RL50® may be used to treat CL caused by L. amazonensis. |
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| 6. | Biochem J. 2011 Sep 1;438(2):303-13.Molecular diversity of the Trypanosoma cruzi TcSMUG family of mucin genes and proteins.Urban I, Santurio LB, Chidichimo A, Yu H, Chen X, Mucci J, Agüero F, Buscaglia CA.SourceInstituto de Investigaciones Biotecnológicas, Universidad Nacional de General San Martín-CONICET, Buenos Aires, Argentina. AbstractThe surface of the protozoan Trypanosoma cruzi is covered by a dense coat of mucin-type glycoconjugates, which make a pivotal contribution to parasite protection and host immune evasion. Their importance is further underscored by the presence of >1000 mucin-like genes in the parasite genome. In the present study we demonstrate that one such group of genes, termed TcSMUG L, codes for previously unrecognized mucin-type glycoconjugates anchored to and secreted from the surface of insect-dwelling epimastigotes. These features are supported by the in vivo tracing and characterization of endogenous TcSMUG L products and recombinant tagged molecules expressed by transfected parasites. Besides displaying substantial homology to TcSMUG S products, which provide the scaffold for the major Gp35/50 mucins also present in insect-dwelling stages of the T. cruzi lifecycle, TcSMUG L products display unique structural and functional features, including being completely refractory to sialylation by parasite trans-sialidases. Although quantitative real time-PCR and gene sequencing analyses indicate a high degree of genomic conservation across the T. cruzi species, TcSMUG L product expression and processing is quite variable among different parasite isolates. |
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