RESUMO
Humans and a wide range of mammals are generally susceptible to Schistosoma infection, while some rodents such as Rattus rats and Microtus spp are not. We previously demonstrated that inherent high expression levels of nitric oxide (NO), produced by inducible nitric oxide synthase (iNOS), plays an important role in blocking the growth and development of Schistosoma japonicum in wild-type rats. However, the potential regulatory effects of NO on the immune system and immune response to S. japonicum infection in rats are still unknown. In this study, we used iNOS-knockout (KO) rats to determine the role of iNOS-derived NO in the immune system and immunopathological responses to S. japonicum infection in rats. Our data showed that iNOS deficiency led to weakened immune activity against S. japonicum infection. This was characterized by the impaired T cell responses and a significant decrease in S. japonicum-elicited Th2/Th1 responses and cytokine and chemokine-producing capability in the infected iNOS-KO rats. Unlike iNOS-KO mice, Th1-associated cytokines were also decreased in the absence of iNOS in rats. In addition, a profile of pro-inflammatory and pro-fibrogenic cytokines was detected in serum associated with iNOS deficiency. The alterations in immune responses and cytokine patterns were correlated with a slower clearance of parasites, exacerbated granuloma formation, and fibrosis following S. japonicum infection in iNOS-KO rats. Furthermore, we have provided direct evidence that high levels of NO in rats can promote the development of pulmonary fibrosis induced by egg antigens of S. japonicum, but not inflammation, which was negatively correlated with the expression of TGF-ß3. These studies are the first description of the immunological and pathological profiles in iNOS-KO rats infected with S. japonicum and demonstrate key differences between the responses found in mice. Our results significantly enhance our understanding of the immunoregulatory effects of NO on defensive and immunopathological responses in rats and the broader nature of resistance to pathogens such as S. japonicum.
Assuntos
Óxido Nítrico Sintase Tipo II , Schistosoma japonicum , Esquistossomose Japônica , Células Th1 , Células Th2 , Animais , Quimiocinas/metabolismo , Citocinas/metabolismo , Óxido Nítrico/metabolismo , Óxido Nítrico Sintase Tipo II/genética , Óxido Nítrico Sintase Tipo II/metabolismo , Óxido Nítrico Sintase Tipo II/fisiologia , Ratos , Esquistossomose Japônica/enzimologia , Esquistossomose Japônica/imunologia , Células Th1/imunologia , Células Th2/imunologiaRESUMO
Toxoplasma gondii can infect almost all warm-blooded vertebrates with pathogensis being largely influenced by the host immune status. As important epidemiological hosts, rodents are globally distributed and are also commonly found infected with haemoflagellates, such as those in the genus Trypanosoma. We here address whether and how co-infection with trypanosomes can influence T. gondii infection in laboratory models. Rats of five strains, co-infected with T. lewisi and mice of four strains, co-infected with T. musculi, were found to be more or less susceptible to T. gondii infection, respectively, with corresponding increased or decreased brain cyst burdens. Downregulation of iNOS expression and decreased NO production or reverse were observed in the peritoneal macrophages of rats or mice, infected with trypanosomes, respectively. Trypanosoma lewisi and T. musculi can modulate host immune responses, either by enhancement or suppression and influence the outcome of Toxoplasma infection.
Assuntos
Toxoplasmose/complicações , Trypanosoma lewisi/fisiologia , Tripanossomíase/complicações , Animais , Western Blotting , Encéfalo/parasitologia , Modelos Animais de Doenças , Macrófagos Peritoneais , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Ratos , Ratos Endogâmicos F344 , Ratos Sprague-Dawley , Ratos Wistar , Organismos Livres de Patógenos Específicos , Esplenomegalia , Toxoplasma/fisiologia , Toxoplasmose/epidemiologia , Trypanosoma/classificação , Trypanosoma/fisiologia , Tripanossomíase/imunologia , Tripanossomíase/parasitologiaRESUMO
Pleomorphic Trypanosoma brucei are best known for their tightly controlled cell growth and developmental program, which ensures their transmissibility and host fitness between the mammalian host and insect vector. However, after long-term adaptation in the laboratory or by natural evolution, monomorphic parasites can be derived. The origin of these monomorphic forms is currently unclear. Here, we produced a series of monomorphic trypanosome stocks by artificially syringe-passage in mice, creating snapshots of the transition from pleomorphism to monomorphism. We then compared these artificial monomorphic trypanosomes, alongside several naturally monomorphic T. evansi and T. equiperdum strains, with the pleomorphic T. brucei. In addition to failing to generate stumpy forms in animal bloodstream, we found that monomorphic trypanosomes from laboratory and nature exhibited distinct differentiation patterns, which are reflected by their distinct differentiation potential and transcriptional changes. Lab-adapted monomorphic trypanosomes could still be induced to differentiate, and showed only minor transcriptional differences to that of the pleomorphic slender forms but some accumulated differences were observed as the passages progress. All naturally monomorphic strains completely fail to differentiate, corresponding to their impaired differentiation regulation. We propose that the natural phenomenon of trypanosomal monomorphism is actually a malignant manifestation of protozoal cells. From a disease epidemiological and evolutionary perspective, our results provide evidence for a new way of thinking about the origin of these naturally monomorphic strains, the malignant evolution of trypanosomes may raise some concerns. Additionally, these monomorphic trypanosomes may reflect the quantitative and qualitative changes in the malignant evolution of T. brucei, suggesting that single-celled protozoa may also provide the most primitive model of cellular malignancy, which could be a primitive and inherent biological phenomenon of eukaryotic organisms from protozoans to mammals.
RESUMO
Kinetoplastid flagellates are known for several unusual features, one of which is their complex mitochondrial genome, known as kinetoplast (k) DNA, composed of mutually catenated maxi- and minicircles. Trypanosoma lewisi is a member of the Stercorarian group of trypanosomes which is, based on human infections and experimental data, now considered a zoonotic pathogen. By assembling a total of 58 minicircle classes, which fall into two distinct categories, we describe a novel type of kDNA organization in T. lewisi. RNA-seq approaches allowed us to map the details of uridine insertion and deletion editing events upon the kDNA transcriptome. Moreover, sequencing of small RNA molecules enabled the identification of 169 unique guide (g) RNA genes, with two differently organized minicircle categories both encoding essential gRNAs. The unprecedented organization of minicircles and gRNAs in T. lewisi broadens our knowledge of the structure and expression of the mitochondrial genomes of these human and animal pathogens. Finally, a scenario describing the evolution of minicircles is presented.
Assuntos
Mitocôndrias/genética , RNA Guia de Cinetoplastídeos/genética , RNA de Protozoário/genética , Trypanosoma lewisi/genética , Adenosina Trifosfatases/genética , DNA de Protozoário/genética , Genoma Mitocondrial , Sequenciamento de Nucleotídeos em Larga Escala , Filogenia , Subunidades Proteicas/genética , Edição de RNARESUMO
Trichomonas vaginalis is a primary urogenital parasite that causes trichomoniasis, a common sexually transmitted disease. As the first line of host defense, vaginal epithelial cells play critical roles in orchestrating vaginal innate immunity and modulate intracellular Cl- homeostasis via the cystic fibrosis transmembrane conductance regulator (CFTR), an anion channel that plays positive roles in regulating nuclear factor-κB (NF-κB) signalling. However, the association between T. vaginalis infection and intracellular Cl- disequilibrium remains elusive. This study showed that after T. vaginalis infection, CFTR was markedly down-regulated by cysteine proteases in vaginal epithelial cells. The intracellular Cl- concentration ([Cl-]i) was consequently elevated, leading to NF-κB signalling activation via serum- and glucocorticoid-inducible kinase-1. Moreover, heightened [Cl-]i and activated NF-κB signalling could be sustained in a positive feedback regulatory manner resulting from decreased intracellular cAMP through NF-κB-mediated up-regulation of phosphodiesterase 4. The results conclusively revealed that the intracellular Cl- of the human vaginal epithelium could be dynamically modulated by T. vaginalis, which contributed to mediation of epithelial inflammation in the human vagina.
Assuntos
Cloretos/metabolismo , Vaginite por Trichomonas/prevenção & controle , Trichomonas vaginalis/efeitos dos fármacos , Vagina/patologia , Western Blotting , Linhagem Celular , Nucleotídeo Cíclico Fosfodiesterase do Tipo 4/metabolismo , Cisteína Proteases/metabolismo , Regulador de Condutância Transmembrana em Fibrose Cística/metabolismo , Regulação para Baixo , Ensaio de Imunoadsorção Enzimática , Epitélio/metabolismo , Epitélio/parasitologia , Epitélio/patologia , Feminino , Humanos , Proteínas Imediatamente Precoces/metabolismo , NF-kappa B/metabolismo , Proteínas Serina-Treonina Quinases/metabolismo , Reação em Cadeia da Polimerase em Tempo Real , Vaginite por Trichomonas/parasitologia , Vagina/metabolismo , Vagina/parasitologiaRESUMO
Toxoplasma gondii is an important human and animal pathogen that causes life-threatening toxoplasmosis. Interferon-γ (IFN-γ) is critical for anti-T. gondii cell-autonomous immunity in both humans and mice. To proliferate efficiently within the hosts, virulent strains of T. gondii can suppress IFN-γ-dependent immunity. During parasite infection, it is well-characterized that various virulence effectors are secreted to transcriptionally or post-translationally target IFN-γ-inducible GTPases, which are essential for anti-parasite responses in mice. However, the role of IFN-γ-inducible GTPases in anti-T. gondii responses in human cells is controversial since they are non-functional or absent in humans. Instead, IFN-γ-induced tryptophan degradation by indole-2,3-dioxygenase (IDO) is important for the anti-T. gondii human response. To date, the T. gondii virulent mechanism targeting IDO in human cells remains elusive. Here we show that although humans possess two IDO isozymes, IDO1 and IDO2, human cells of various origins require IDO1 but not IDO2 for IFN-γ-induced cell-autonomous immunity to T. gondii. T. gondii secretes an effector TgIST to inhibit IDO1 mRNA expression. Taken together, the data suggests that T. gondii possesses virulence programs operated by TgIST to antagonize IFN-γ-induced IDO1-mediated anti-parasite cell-autonomous immunity in human cells.
Assuntos
Imunidade Celular/imunologia , Indolamina-Pirrol 2,3,-Dioxigenase/imunologia , Interferon gama/imunologia , Toxoplasma/imunologia , Toxoplasmose/imunologia , Animais , Autofagia/genética , Autofagia/imunologia , Proteínas Relacionadas à Autofagia/genética , Proteínas Relacionadas à Autofagia/imunologia , Proteínas Relacionadas à Autofagia/metabolismo , Linhagem Celular Tumoral , Células Cultivadas , GTP Fosfo-Hidrolases/genética , GTP Fosfo-Hidrolases/imunologia , GTP Fosfo-Hidrolases/metabolismo , Células HeLa , Humanos , Imunidade Celular/genética , Indolamina-Pirrol 2,3,-Dioxigenase/genética , Indolamina-Pirrol 2,3,-Dioxigenase/metabolismo , Interferon gama/metabolismo , Camundongos Knockout , Toxoplasma/patogenicidade , Toxoplasmose/enzimologia , Toxoplasmose/parasitologia , Virulência/genética , Virulência/imunologiaRESUMO
Trypanosoma musculi, a common blood flagellate found in mice, is similar in morphology and life cycle to the rat trypanosome T. lewisi. Both species belong to the subgenus Herpetosoma, and as T. lewisi has recently been shown to be a zoonotic pathogen, there is concern that T. musculi could also be potentially infective to humans. To test this hypothesis, a well-established method, the normal human serum (NHS) incubation test, was carried out which distinguishes human and non-human infective trypanosomes. We found that T. musculi could grow in 0.31% NHS in vitro, and even kept their infectivity to mice after incubation with 10% NHS for 24â¯h. In in vivo experiments, T. musculi were only slightly affected by NHS injection, confirming that it was less sensitive to the NHS than T. b. brucei, but more sensitive than T. lewisi. This resistance probably does not rely on a restricted uptake of ApoL-1. Due to this partial resistance, we cannot definitively confirm that T. musculi has the potential for infection to humans. As resistance is less than that of T. lewisi, our data suggest that it is unlikely to be a zoonotic pathogen although we would advise caution in the case of immunocompromised people such as AIDS and cancer patients.
Assuntos
Hospedeiro Imunocomprometido/imunologia , Soro/imunologia , Trypanosoma/imunologia , Tripanossomíase/imunologia , Adulto , Animais , Apolipoproteína L1/genética , Apolipoproteína L1/imunologia , Apolipoproteína L1/metabolismo , Western Blotting , DNA de Protozoário/química , DNA de Protozoário/isolamento & purificação , DNA Ribossômico/química , Eletroforese em Gel de Poliacrilamida , Endocitose/imunologia , Haplótipos , Humanos , Hospedeiro Imunocomprometido/genética , Camundongos , Parasitemia/imunologia , Parasitemia/parasitologia , Reação em Cadeia da Polimerase , RNA Ribossômico 18S/genética , Ratos , Ratos Sprague-Dawley , Alinhamento de Sequência , Trypanosoma/genética , Tripanossomíase/genética , Tripanossomíase/parasitologiaRESUMO
Human schistosomiasis, caused by Schistosoma species, is a major public health problem affecting more than 700 million people in 78 countries, with over 40 mammalian host reservoir species complicating the transmission ecosystem. The primary cause of morbidity is considered to be granulomas induced by fertilized eggs of schistosomes in the liver and intestines. Some host species, like rats (Rattus norvegicus), are naturally intolerant to Schistosoma japonicum infection, and do not produce granulomas or pose a threat to transmission, while others, like mice and hamsters, are highly susceptible. The reasons behind these differences are still a mystery. Using inducible nitric oxide synthase knockout (iNOS-/-) Sprague-Dawley rats, we found that inherent high expression levels of iNOS in wild-type (WT) rats play an important role in blocking growth, reproductive organ formation, and egg development in S. japonicum, resulting in production of nonfertilized eggs. Granuloma formation, induced by fertilized eggs in the liver, was considerably exacerbated in the iNOS-/- rats compared with the WT rats. This inhibition by nitric oxide acts by affecting mitochondrial respiration and energy production in the parasite. Our work not only elucidates the innate mechanism that blocks the development and production of fertilized eggs in S. japonicum but also offers insights into a better understanding of host-parasite interactions and drug development strategies against schistosomiasis.
Assuntos
Interações Hospedeiro-Parasita , Óxido Nítrico Sintase Tipo II/metabolismo , Óxido Nítrico , Schistosoma japonicum/crescimento & desenvolvimento , Transferência Adotiva , Animais , Respiração Celular , Feminino , Masculino , Camundongos Endogâmicos BALB C , Óxido Nítrico Sintase Tipo II/genética , Ratos Sprague-Dawley , Schistosoma japonicum/metabolismoRESUMO
Mesenchymal stromal cells (MSCs) have recently been shown to play important roles in mammalian host defenses against intracellular pathogens, but the molecular mechanism still needs to be clarified. We confirmed that human MSCs (hMSCs) prestimulated with IFN-γ showed a significant and dose-dependent ability to inhibit the growth of two types of Toxoplasma gondii [type I RH strain with green fluorescent proteins (RH/GFP) or type II PLK strain with red fluorescent proteins (PLK/RED)]. However, in contrast to previous reports, the anti-T. gondii activity of hMSCs was not mediated by indoleamine 2,3-dioxygenase (IDO). Genome-wide RNA sequencing (RNA-seq) analysis revealed that IFN-γ increased the expression of the p65 family of human guanylate-binding proteins (hGBPs) in hMSCs, especially hGBP1. To analyze the functional role of hGBPs, stable knockdowns of hGBP1, -2, and -5 in hMSCs were established using a lentiviral transfection system. hGBP1 knockdown in hMSCs resulted in a significant loss of the anti-T. gondii host defense property, compared with hMSCs infected with nontargeted control sequences. hGBP2 and -5 knockdowns had no effect. Moreover, the hGBP1 accumulation on the parasitophorous vacuole (PV) membranes of IFN-γ-stimulated hMSCs might protect against T. gondii infection. Taken together, our results suggest that hGBP1 plays a pivotal role in anti-T. gondii protection of hMSCs and may shed new light on clarifying the mechanism of host defense properties of hMSCs.
Assuntos
Proteínas de Ligação ao GTP/imunologia , Células-Tronco Mesenquimais/imunologia , Toxoplasma/imunologia , Vacúolos/imunologia , Animais , Células Cultivadas , Embrião de Mamíferos/citologia , Fibroblastos/citologia , Fibroblastos/imunologia , Fibroblastos/parasitologia , Proteínas de Ligação ao GTP/genética , Proteínas de Ligação ao GTP/metabolismo , Expressão Gênica/efeitos dos fármacos , Expressão Gênica/imunologia , Células HeLa , Interações Hospedeiro-Parasita/efeitos dos fármacos , Interações Hospedeiro-Parasita/imunologia , Humanos , Interferon gama/imunologia , Interferon gama/farmacologia , Proteínas Luminescentes/genética , Proteínas Luminescentes/metabolismo , Células-Tronco Mesenquimais/metabolismo , Células-Tronco Mesenquimais/parasitologia , Camundongos , Interferência de RNA , Toxoplasma/genética , Toxoplasma/fisiologia , Vacúolos/efeitos dos fármacos , Vacúolos/parasitologiaRESUMO
The subgenus Trypanozoon includes three species Trypanosoma brucei, Trypanosoma evansi and Trypanosoma equiperdum, which are morphologically identical and indistinguishable even using some molecular methods. In this study, PCR-based single strand conformation polymorphism (PCR-SSCP) was used to analyze the ribosomal DNA of the Trypanozoon species. Data indicate different patterns of ITS2 fragments between T. brucei, T. evansi and T. equiperdum by SSCP. Furthermore, analysis of total ITS sequences within these three members of the subgenus Trypanozoon showed a high degree of homology using phylogenetic analysis but were polyphyletic in haplotype networks. These data provide novel nuclear evidence to further support the notion that T. evansi and T. equiperdum should be subspecies or even strains of T. brucei.
Assuntos
DNA de Protozoário/genética , DNA Ribossômico/genética , Filogenia , Trypanosoma brucei brucei/classificação , Trypanosoma/classificação , Tripanossomíase/epidemiologia , África/epidemiologia , Animais , Sequência de Bases , China/epidemiologia , Haplótipos , Humanos , Insetos Vetores/parasitologia , Reação em Cadeia da Polimerase , Polimorfismo Conformacional de Fita Simples , Alinhamento de Sequência , Homologia de Sequência do Ácido Nucleico , Trypanosoma/genética , Trypanosoma/isolamento & purificação , Trypanosoma brucei brucei/genética , Trypanosoma brucei brucei/isolamento & purificação , Tripanossomíase/parasitologia , Tripanossomíase/transmissão , Moscas Tsé-Tsé/parasitologiaRESUMO
The oriental liver fluke, Clonorchis sinensis, a pathogen causing clonorchiasis, is of major socio-economic importance in East Asia, including China, Korea and Vietnam. This parasite is now recognized as a biocarcinogen strongly linked to cholangiocarcinoma in humans. Here, we describe the status of clonorchiasis in China, where it has been estimated that more than 15 million patients are affected. This paper also summarizes the major advances in the field of clonorchiasis research during last decade, including diagnosis techniques, pathogenesis and genome/transcriptome/proteome studies in the last years. We strongly hope that our work can stimulate the governments of the countries or regions where clonorchiasis is endemic to pay more attention to this disease and establish related guidelines to prevent and control it.
Assuntos
Clonorquíase/epidemiologia , Clonorchis sinensis , Animais , Anti-Helmínticos/uso terapêutico , China/epidemiologia , Clonorquíase/diagnóstico , Clonorquíase/tratamento farmacológico , Clonorchis sinensis/genética , Clonorchis sinensis/isolamento & purificação , Clonorchis sinensis/fisiologia , DNA de Helmintos/análise , Variação Genética , Interações Hospedeiro-Parasita/fisiologia , Humanos , Estágios do Ciclo de VidaRESUMO
Cancer is a general name for more than 100 malignant diseases. It is postulated that all cancers start from a single abnormal cell that grows out of control. Untreated cancers can cause serious consequences and deaths. Great progress has been made in cancer research that has significantly improved our knowledge and understanding of the nature and mechanisms of the disease, but the origins of cancer are far from being well understood due to the limitations of suitable model systems and to the complexities of the disease. In view of the fact that cancers are found in various species of vertebrates and other metazoa, here, we suggest that cancer also occurs in parasitic protozoans such as Trypanosoma brucei, a blood parasite, and Toxoplasma gondii, an obligate intracellular pathogen. Without treatment, these protozoan cancers may cause severe disease and death in mammals, including humans. The simpler genomes of these single-cell organisms, in combination with their complex life cycles and fascinating life cycle differentiation processes, may help us to better understand the origins of cancers and, in particular, leukemias.
Assuntos
Neoplasias/patologia , Parasitos/fisiologia , Toxoplasma/fisiologia , Trypanosoma brucei brucei/fisiologia , Animais , Proliferação de Células , Humanos , Estágios do Ciclo de Vida , Modelos Biológicos , Mutação/genética , Metástase Neoplásica , Neoplasias/genética , Toxoplasma/genética , Toxoplasma/crescimento & desenvolvimento , Trypanosoma brucei brucei/genética , Trypanosoma brucei brucei/crescimento & desenvolvimentoRESUMO
Mouse models differ considerably from humans with regard to clinical symptoms of toxoplasmosis caused by Toxoplasma gondii and, by comparison, the rat model is more representative of this disease in humans. In the present study, we found that different strains of adult and newborn rats (Lewis, Wistar, Sprague Dawley, Brown Norway and Fischer 344) exhibited remarkable variation in the number of brain cysts following inoculation with the T.gondii Prugniaud strain. In adult rats, large numbers of cysts (1231 ± 165.6) were observed in Fischer 344, but none in the other four. This situation was different in newborn rats aged from 5 to 20 days old. All Fischer 344 and Brown Norway newborns were cyst-positive while cyst-positive infection in Sprague Dawley neonates ranged from 54.5% to 60% depending on their age at infection. In Wistar and Lewis rat neonates, however, cyst-positivity rates of 0-42.9% and 0-25% were found respectively. To investigate whether rat strain differences in infectivity could be related to inherent strain and genetic differences in the host immune response, we correlated our data with previously reported strain differences in iNOS/Arginase ratio in adult rats and found them to be linked. These results show that interactions between host genetic background and age of rat influence T.gondii infection.
Assuntos
Arginase/metabolismo , Óxido Nítrico Sintase Tipo II/metabolismo , Toxoplasma/crescimento & desenvolvimento , Toxoplasmose Animal/genética , Toxoplasmose Animal/metabolismo , Fatores Etários , Análise de Variância , Animais , Animais Recém-Nascidos , Encéfalo/parasitologia , Distribuição de Qui-Quadrado , Modelos Animais de Doenças , Resistência à Doença/genética , Suscetibilidade a Doenças , Feminino , Masculino , Ratos , Ratos Endogâmicos BN , Ratos Endogâmicos F344 , Ratos Endogâmicos Lew , Ratos Sprague-Dawley , Ratos Wistar , Especificidade da Espécie , Toxoplasma/patogenicidade , Toxoplasmose Animal/enzimologia , Toxoplasmose Cerebral/genética , Toxoplasmose Cerebral/parasitologiaRESUMO
The canonical photosynthetic plastid genomes consist of a single circular-mapping chromosome that encodes a highly conserved protein core, involved in photosynthesis and ATP generation. Here, we demonstrate that the plastid genome of the photosynthetic relative of apicomplexans, Chromera velia, departs from this view in several unique ways. Core photosynthesis proteins PsaA and AtpB have been broken into two fragments, which we show are independently transcribed, oligoU-tailed, translated, and assembled into functional photosystem I and ATP synthase complexes. Genome-wide transcription profiles support expression of many other highly modified proteins, including several that contain extensions amounting to hundreds of amino acids in length. Canonical gene clusters and operons have been fragmented and reshuffled into novel putative transcriptional units. Massive genomic coverage by paired-end reads, coupled with pulsed-field gel electrophoresis and polymerase chain reaction, consistently indicate that the C. velia plastid genome is linear-mapping, a unique state among all plastids. Abundant intragenomic duplication probably mediated by recombination can explain protein splits, extensions, and genome linearization and is perhaps the key driving force behind the many features that defy the conventional ways of plastid genome architecture and function.
Assuntos
Complexos de ATP Sintetase/genética , Alveolados/genética , Genoma de Protozoário , Complexo de Proteína do Fotossistema I/genética , Proteínas de Protozoários/genética , Complexos de ATP Sintetase/química , Complexos de ATP Sintetase/metabolismo , Trifosfato de Adenosina/metabolismo , Sequência de Bases , Mapeamento Cromossômico , Evolução Molecular , Perfilação da Expressão Gênica , Modelos Moleculares , Dados de Sequência Molecular , Família Multigênica , Fotossíntese/genética , Complexo de Proteína do Fotossistema I/química , Complexo de Proteína do Fotossistema I/metabolismo , Estrutura Terciária de Proteína , Proteínas de Protozoários/química , Proteínas de Protozoários/metabolismoRESUMO
Polyprenyl-diphosphate synthase is a key enzyme in the biosynthesis of ubiquinone, a molecule considered essential for a typical eukaryotic cell. Its orthologue in the American stercorarian flagellate Trypanosoma cruzi, solanesyl diphosphate synthase, has been previously localized into the glycosomes. We wondered whether this unique cellular localization is shared by other trypanosome species. Using digitonin permeabilization, immunofluorescence and in situ tagging techniques, we show that in Trypanosoma brucei, the African salivarian flagellate, the enzyme localizes to the mitochondrion.
Assuntos
Alquil e Aril Transferases/análise , Mitocôndrias/química , Mitocôndrias/enzimologia , Trypanosoma brucei brucei/química , Trypanosoma brucei brucei/enzimologia , Humanos , Microscopia de FluorescênciaRESUMO
Throughout eukaryotes, the gene encoding subunit 6 (ATP6) of the F(1)F(O)-ATP synthase (complex V) is maintained in mitochondrial (mt) genomes, presumably because of its high hydrophobicity due to its incorporation into the membrane-bound F(O) moiety. In Trypanosoma species, a mt transcript that undergoes extensive processing by RNA editing has a very low sequence similarity to ATP6 from other organisms. The notion that the putative ATP6 subunit is assembled into the F(O) sub-complex is ostensibly challenged by the existence of naturally occurring dyskinetoplastic (Dk) and akinetoplastid (Ak) trypanosomes, which are viable despite lacking the mtDNA required for its expression. Taking advantage of the different phenotypes between RNA interference knock-down cell lines in which the expression of proteins involved in mtRNA metabolism and editing can be silenced, we provide support for the view that ATP6 is encoded in the mt genome of Trypanosoma species and that it is incorporated into complex V. The reduction of the F(1)F(O) oligomer of complex V coincides with the accumulation of the F(1) moiety in ATP6-lacking cells, which also appear to lack the F(O) ATP9 multimeric ring. The oligomycin sensitivity of ATPase activity of complex V in ATP6-lacking cells is reduced, reflecting the insensitivity of the Dk and Ak cells to this drug. In addition, the F(1) moiety of complex V appears to exist as a dimer in steady state conditions and contains the ATP4 subunit traditionally assigned to the F(O) sub-complex.
Assuntos
ATPases Translocadoras de Prótons/antagonistas & inibidores , ATPases Translocadoras de Prótons/metabolismo , Edição de RNA , Interferência de RNA , Trypanosoma brucei brucei/enzimologia , Animais , Inibidores Enzimáticos/farmacologia , Potenciais da Membrana , Mitocôndrias/genética , Mitocôndrias/metabolismo , Oligomicinas/farmacologia , ATPases Translocadoras de Prótons/genética , Proteínas de Protozoários/genética , Proteínas de Protozoários/metabolismo , Trypanosoma brucei brucei/efeitos dos fármacos , Trypanosoma brucei brucei/genética , Trypanosoma brucei brucei/crescimento & desenvolvimentoRESUMO
The oriental liverfluke, Clonorchis sinensis, is of major socioeconomic importance in parts of Asia, including China, Japan, Korea, Taiwan, and Vietnam. The parasite is transmitted via snails to freshwater fish, and then to human beings and other piscivorous mammals, and causes substantial clinical or subclinical disease, known as clonorchiasis. There is considerable evidence for an aetiological relation between clonorchiasis and cholangiocarcinoma in human beings. It is estimated that about 35 million people are infected globally, of whom approximately 15 million are in China. Although very little information from China has been published in the English language, recent analyses of epidemiological data sets suggest that clonorchiasis is having an increased human-health impact due to the greater consumption of raw freshwater fish. To gain an improved insight into clonorchiasis in China, this review provides a background on the parasite and its life cycle, summarises key aspects regarding the pathogenesis, diagnosis, and treatment of clonorchiasis, describes the geographic distribution and prevalence of clonorchiasis, and makes some recommendations for future research and the control of this important disease.