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1.
J Cell Sci ; 134(5)2021 03 10.
Artículo en Inglés | MEDLINE | ID: mdl-33692153

RESUMEN

Chagas disease (American trypanosomiasis) is a 'neglected' pathology that affects millions of people worldwide, mainly in Latin America. Trypanosoma cruzi, the causative agent, is an obligate intracellular parasite with a complex and diverse biology that infects several mammalian species, including humans. Because of genetic variability among strains and the presence of four biochemically and morphologically distinct parasite forms, the outcome of T. cruzi infection varies considerably depending on host cell type and parasite strain. During the initial contact, cellular communication is established by host-recognition-mediated responses, followed by parasite adherence and penetration. For this purpose, T. cruzi expresses a variety of proteins that modify the host cell, enabling it to safely reach the cytoplasm. After entry into the host cell, T. cruzi forms a transitory structure termed 'parasitophorous vacuole' (PV), followed by its cytoplasmic replication and differentiation after PV rupture, and subsequent invasion of other cells. The success of infection, maintenance and survival inside host cells is facilitated by the ability of T. cruzi to subvert various host signaling mechanisms. We focus in this Review on the various mechanisms that induce host cytoskeletal rearrangements, activation of autophagy-related proteins and crosstalk among major immune response regulators, as well as recent studies on the JAK-STAT pathway.


Asunto(s)
Enfermedad de Chagas , Trypanosoma cruzi , Animales , Comunicación Celular , Citoplasma , Humanos , Transducción de Señal
2.
Cell Microbiol ; 17(12): 1797-810, 2015 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-26096820

RESUMEN

Trypanosoma cruzi extracellular amastigotes (EAs) display unique mechanisms for cell invasion that are highly dependent on host actin filaments. Protein kinase D1 (PKD1) phosphorylates and modulates the activity of cortactin, a key regulator of actin dynamics. We evaluated the role of host cortactin and PKD1 in actin filament dynamics during HeLa cell invasion by EAs. Host cortactin, PKD1 and actin are recruited by EAs based on experiments in fixed and live cells by time lapse confocal microscopy. EAs trigger PKD1 and extracellular signal-regulated kinase 1/2 activation, but not Src family kinases, and selectively phosphorylate cortactin. Heat-killed EAs and non-infective epimastigotes both triggered distinct host responses and did not recruit the molecules studied herein. EA invasion was influenced by depletion or overexpression of host cortactin and PKD1, respectively, suggesting the involvement of both proteins in this event. Collectively, these results show new host cell mechanisms subverted during EA internalization into non-phagocytic cells.


Asunto(s)
Actinas/metabolismo , Cortactina/metabolismo , Endocitosis , Interacciones Huésped-Patógeno , Proteína Quinasa C/metabolismo , Transducción de Señal , Trypanosoma cruzi/fisiología , Células Epiteliales/parasitología , Células Epiteliales/fisiología , Células HeLa , Humanos , Microscopía Confocal , Análisis de Secuencia de ADN , Imagen de Lapso de Tiempo
3.
Microbes Infect ; : 105385, 2024 Jun 29.
Artículo en Inglés | MEDLINE | ID: mdl-38950642

RESUMEN

Trypanosoma cruzi, the etiological agent of Chagas' disease, can infect both phagocytic and non-phagocytic cells. T. cruzi gp82 and gp90 are cell surface proteins belonging to Group II trans-sialidases known to be involved in host cell binding and invasion. Phosphatidylinositol kinases (PIK) are lipid kinases that phosphorylate phospholipids in their substrates or in themselves, regulating important cellular functions such as metabolism, cell cycle and survival. Vps34, a class III PIK, regulates autophagy, trimeric G-protein signaling, and the mTOR (mammalian Target of Rapamycin) nutrient-sensing pathway. The mammalian autophagy gene Beclin1 interacts to Vps34 forming Beclin 1-Vps34 complexes involved in autophagy and protein sorting. In T. cruzi epimastigotes, (a non-infective replicative form), TcVps34 has been related to morphological and functional changes associated to vesicular trafficking, osmoregulation and receptor-mediated endocytosis. We aimed to characterize the role of TcVps34 during invasion of HeLa cells by metacyclic (MT) forms. MTs overexpressing TcVps34 showed lower invasion rates compared to controls, whilst exhibiting a significant decrease in gp82 expression in the parasite surface. In addition, we showed that T. cruzi Beclin (TcBeclin1) colocalizes with TcVps34 in epimastigotes, thus suggesting the formation of complexes that may play conserved cellular roles already described for other eukaryotes.

4.
Front Microbiol ; 13: 901442, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-35898912

RESUMEN

Candida albicans is a human commensal fungus and the etiologic agent of nosocomial infections in immunocompromised individuals. Candida spp. is the most studied human fungal pathogen, and the mechanisms by which this fungus can evade the immune system affecting immunosuppressed individuals have been extensively studied. Most of these studies focus on different species of Candida, and there is much to be understood in virulence variability among lineages, specifically different C. albicans clinical isolates. To better understand the main mechanisms of its virulence variability modulated in C. albicans clinical isolates, we characterized L3881 lineage, which has been previously classified as hypovirulent, and SC5314 lineage, a virulent wild-type control, by using both in vitro and in vivo assays. Our findings demonstrated that L3881 presented higher capacity to avoid macrophage phagocytosis and higher resistance to oxidative stress than the wild type. These characteristics prevented higher mortality rates for L3881 in the animal model of candidiasis. Conversely, L3881 has been able to induce an upregulation of pro-inflammatory mediators both in vitro and in vivo. These results indicated that in vitro and in vivo functional characterizations are necessary for determination of virulence in different clinical isolates due to its modulation in the host-pathogen interactions.

5.
Front Cell Infect Microbiol ; 12: 905757, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-36250059

RESUMEN

In early 2020, one of the most prevalent symptoms of SARS-CoV-2 infection was the loss of smell (anosmia), found in 60-70% of all cases. Anosmia used to occur early, concomitantly with other symptoms, and often persisted after recovery for an extended period, sometimes for months. In addition to smell disturbance, COVID-19 has also been associated with loss of taste (ageusia). The latest research suggests that SARS-CoV-2 could spread from the respiratory system to the brain through receptors in sustentacular cells localized to the olfactory epithelium. The virus invades human cells via the obligatory receptor, angiotensin-converting enzyme II (ACE2), and a priming protease, TMPRSS2, facilitating viral penetration. There is an abundant expression of both ACE2 and TMPRSS2 in sustentacular cells. In this study, we evaluated 102 COVID-19 hospitalized patients, of which 17.60% presented anosmia and 9.80% ageusia. ACE1, ACE2, and TMPRSS2 gene expression levels in nasopharyngeal tissue were obtained by RT-qPCR and measured using ΔCT analysis. ACE1 Alu287bp association was also evaluated. Logistic regression models were generated to estimate the effects of variables on ageusia and anosmia Association of ACE2 expression levels with ageusia. was observed (OR: 1.35; 95% CI: 1.098-1.775); however, no association was observed between TMPRSS2 and ACE1 expression levels and ageusia. No association was observed among the three genes and anosmia, and the Alu287bp polymorphism was not associated with any of the outcomes. Lastly, we discuss whetherthere is a bridge linking these initial symptoms, including molecular factors, to long-term COVID-19 health consequences such as cognitive dysfunctions.


Asunto(s)
Ageusia , Enzima Convertidora de Angiotensina 2/genética , COVID-19 , Trastornos del Olfato , Ageusia/etiología , Anosmia , COVID-19/genética , Cognición , Expresión Génica , Humanos , Trastornos del Olfato/genética , Receptores de Angiotensina , SARS-CoV-2
6.
Biochem Biophys Res Commun ; 408(3): 427-31, 2011 May 13.
Artículo en Inglés | MEDLINE | ID: mdl-21514274

RESUMEN

Protein tyrosine phosphatases (PTPs) form a large family of enzymes involved in the regulation of numerous cellular functions in eukaryotes. Several protein tyrosine phosphatases have been recently identified in trypanosomatides. Here we report the purification and biochemical characterization of TcPTP1, a protein tyrosine phosphatase from Trypanosoma cruzi, the causing agent of Chagas' disease. The enzyme was cloned and expressed recombinantly in Escherichia coli and purified by Ni-affinity chromatography. Biochemical characterization of recombinant TcPTP1 with the PTP pseudo-substrate pNPP allowed the estimation of a Michaelis-Menten constant K(m) of 4.5mM and a k(cat) of 2.8s(-1). We were able to demonstrate inhibition of the enzyme by the PTP1b inhibitor BZ3, which on its turn was able to accelerate the differentiation of epimastigotes into metacyclic forms of T. cruzi induced by nutritional stress. Additionally, this compound was able to inhibit by 50% the infectivity of T. cruzi trypomastigotes in a separate cellular assay. In conclusion our results indicate that TcPTP1 is of importance for cellular differentiation and invasivity of this parasite and thus is a valid target for the rational drug design of potential antibiotics directed against T. cruzi.


Asunto(s)
Proteínas Tirosina Fosfatasas/química , Trypanosoma cruzi/enzimología , Trypanosoma cruzi/patogenicidad , Ciclo Celular , Proteínas Tirosina Fosfatasas/genética
7.
Mem Inst Oswaldo Cruz ; 105(4): 391-7, 2010 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-20721481

RESUMEN

CA88 is the first long nuclear repetitive DNA sequence identified in the blood fluke, Schistosoma mansoni. The assembled S. mansoni sequence, which contains the CA88 repeat, has 8,887 nucleotides and at least three repeat units of approximately 360 bp. In addition, CA88 also possesses an internal CA microsatellite, identified as SmBr18. Both PCR and BLAST analysis have been used to analyse and confirm the CA88 sequence in other S. mansoni sequences in the public database. PCR-acquired nuclear repetitive DNA sequence profiles from nine Schistosoma species were used to classify this organism into four genotypes. Included among the nine species analysed were five sequences of both African and Asian lineages that are known to infect humans. Within these genotypes, three of them refer to recognised species groups. A panel of four microsatellite loci, including SmBr18 and three previously published loci, has been used to characterise the nine Schistosoma species. Each species has been identified and classified based on its CA88 DNA fingerprint profile. Furthermore, microsatellite sequences and intra-specific variation have also been observed within the nine Schistosoma species sequences. Taken together, these results support the use of these markers in studying the population dynamics of Schistosoma isolates from endemic areas and also provide new methods for investigating the relationships between different populations of parasites. In addition, these data also indicate that Schistosoma magrebowiei is not a sister taxon to Schistosoma mattheei, prompting a new designation to a basal clade.


Asunto(s)
ADN de Helmintos/genética , Repeticiones de Microsatélite/genética , Secuencias Repetitivas de Ácidos Nucleicos/genética , Schistosoma/genética , Animales , Dermatoglifia del ADN , Genotipo , Filogenia , Reacción en Cadena de la Polimerasa , Schistosoma/clasificación , Schistosoma mansoni/genética
8.
Front Cell Dev Biol ; 8: 396, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32587854

RESUMEN

The trypanosomatid (protozoan) parasites Trypanosoma cruzi and Leishmania spp. are causative agents of Chagas disease and Leishmaniasis, respectively. They display high morphological plasticity, are capable of developing in both invertebrate and vertebrate hosts, and are the only trypanosomatids that can survive and multiply inside mammalian host cells. During internalization by host cells, these parasites are lodged in "parasitophorous vacuoles" (PVs) comprised of host cell endolysosomal system components. PVs effectively shelter parasites within the host cell. PV development and maturation (acidification, acquisition of membrane markers, and/or volumetric expansion) precede parasite escape from the vacuole and ultimately from the host cell, which are key determinants of infective burden and persistence. PV biogenesis varies, depending on trypanosomatid species, in terms of morphology (e.g., size), biochemical composition, and parasite-mediated processes that coopt host cell machinery. PVs play essential roles in the intracellular development (i.e., morphological differentiation and/or multiplication) of T. cruzi and Leishmania spp. They are of great research interest as potential gateways for drug delivery systems and other therapeutic strategies for suppression of parasite multiplication and control of the large spectrum of diseases caused by these trypanosomatids. This mini-review focuses on mechanisms of PV biogenesis, and processes whereby PVs of T. cruzi and Leishmania spp. promote parasite persistence within and dissemination among mammalian host cells.

9.
Front Cell Dev Biol ; 8: 439, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32582714

RESUMEN

The World Health Organization (WHO) has estimated that in 2016, there were 87 million new cases of gonorrhea. Gonorrhea is caused by the sexually transmitted human-exclusive agent Neisseria gonorrhoeae, a Gram-negative diplococcus that causes cervicitis in females and urethritis in males and may lead to more severe complications. Currently, there is no vaccine against N. gonorrhoeae. Its resistance to antibiotics has been increasing in the past few years, reducing the range of treatment options. N. gonorrhoeae requires a surface protein/receptor (Opa proteins, porin, Type IV pili, LOS) to adhere to and invade epithelial cells. During invasion and transcytosis, N. gonorrhoeae is targeted by the autophagy pathway, a cellular maintenance process which balances sources of energy at critical times by degrading damaged organelles and macromolecules in the lysosome. Autophagy is an important host defense mechanism which targets invading pathogens. Based on transmission electron microscopy (TEM) analysis, the intracellular bacteria occupy the autophagosome, a double-membraned vesicle that is formed around molecules or microorganisms during macroautophagy and fuses with lysosomes for degradation. Most of the gonococci end up in autolysosomes for degradation, but a subpopulation of the intracellular bacteria inhibits the maturation of the autophagosome and its fusion with lysosomes by activating mTORC1 (a known suppressor of the autophagy signaling), thus escaping autophagic elimination. This mini review focuses on the cellular features of N. gonorrhoeae during epithelial cell invasion, with a particular focus on how N. gonorrhoeae evades the autophagy pathway.

10.
Front Immunol ; 11: 1774, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32973747

RESUMEN

Chagas disease, a zoonosis caused by the flagellate protozoan Trypanosoma cruzi, is a chronic and systemic parasitic infection that affects ~5-7 million people worldwide, mainly in Latin America. Chagas disease is an emerging public health problem due to the lack of vaccines and effective treatments. According to recent studies, several T. cruzi secreted proteins interact with the human host during cell invasion. Moreover, some comparative studies with T. rangeli, which is non-pathogenic in humans, have been performed to identify proteins directly involved in the pathogenesis of the disease. In this study, we present an integrated analysis of canonical putative secreted proteins (PSPs) from both species. Additionally, we propose an interactome with human host and gene family clusters, and a phylogenetic inference of a selected protein. In total, we identified 322 exclusively PSPs in T. cruzi and 202 in T. rangeli. Among the PSPs identified in T. cruzi, we found several trans-sialidases, mucins, MASPs, proteins with phospholipase 2 domains (PLA2-like), and proteins with Hsp70 domains (Hsp70-like) which have been previously characterized and demonstrated to be related to T. cruzi virulence. PSPs found in T. rangeli were related to protozoan metabolism, specifically carboxylases and phosphatases. Furthermore, we also identified PSPs that may interact with the human immune system, including heat shock and MASP proteins, but in a lower number compared to T. cruzi. Interestingly, we describe a hypothetical hybrid interactome of PSPs which reveals that T. cruzi secreted molecules may be down-regulating IL-17 whilst T. rangeli may enhance the production of IL-15. These results will pave the way for a better understanding of the pathophysiology of Chagas disease and may ultimately lead to the identification of molecular targets, such as key PSPs, that could be used to minimize the health outcomes of Chagas disease by modulating the immune response triggered by T. cruzi infection.


Asunto(s)
Enfermedad de Chagas/parasitología , Proteoma , Proteínas Protozoarias/metabolismo , Trypanosoma cruzi/metabolismo , Trypanosoma rangeli/metabolismo , Enfermedad de Chagas/inmunología , Enfermedad de Chagas/metabolismo , Biología Computacional , Regulación Viral de la Expresión Génica , Redes Reguladoras de Genes , Genómica , Interacciones Huésped-Patógeno , Humanos , Filogenia , Mapas de Interacción de Proteínas , Proteínas Protozoarias/genética , Proteínas Protozoarias/inmunología , Vías Secretoras , Transducción de Señal , Trypanosoma cruzi/genética , Trypanosoma cruzi/inmunología , Trypanosoma rangeli/genética , Trypanosoma rangeli/inmunología
11.
Immunobiology ; 225(3): 151904, 2020 05.
Artículo en Inglés | MEDLINE | ID: mdl-31959539

RESUMEN

B cells contribute to the immune system in many ways such as antigen presentation to CD4+ T cells, secretion of cytokines and lymphoid tissue organogenesis. Furthermore, they are the only cell type capable of producing immunoglobulins. B cells also account for critical aspects of the resistance against intracellular pathogens. Trypanosoma cruzi is an intracellular parasite that sabotages humoral response by depletion of immature B cells. Polyclonal activation and secretion of non-specific antibodies are also other mechanisms used by T cruzi to evade and subvert the mammalian host immune system, leading to increased parasitemia and susceptibility to Chagas' disease. It remained unclear whether B cell depletion occurs due to direct contact with T. cruzi or results from a global increase in inflammation. Unlike previous reports, we demonstrated in this study that T. cruzi infects human B cells, resulting in parasite-induced activation of caspase-7 followed by proteolytic cleavage of phospholipase Cγ1 and cell death. These data contribute to explain the mechanisms ruling B-cell depletion and evasion of the immune response by T. cruzi.


Asunto(s)
Actinas/metabolismo , Linfocitos B/inmunología , Linfocitos B/metabolismo , Caspasa 7/metabolismo , Interacciones Huésped-Patógeno , Fosfolipasa C gamma/metabolismo , Trypanosoma cruzi/inmunología , Muerte Celular , Enfermedad de Chagas/inmunología , Enfermedad de Chagas/metabolismo , Enfermedad de Chagas/parasitología , Humanos , Proteolisis
12.
Biochem Biophys Res Commun ; 380(3): 525-30, 2009 Mar 13.
Artículo en Inglés | MEDLINE | ID: mdl-19250641

RESUMEN

Phosphatidylinositol kinases (PIK) are at the heart of one of the major pathways of intracellular signal transduction. The signals made by PIK influence a wide variety of cellular functions, including cell growth, differentiation and survival, glucose metabolism and cytoskeletal organization. Wortmannin strongly binds in vitro to all PIK subtypes and it is therefore an effective antiproliferative agent. This study is the first report on a survey made by similarity searches against Schistosoma mansoni genome available to date for phosphatidylinositol- and related-kinases (SmPIKs). We classified the SmPIKs according to five models (1-5). SmPIK sequences were retrieved from GeneDB (http://www.genedb.org) by means of a combinatorial approach which uses terms defined in genome annotation associated with PFAM (Protein Families) domains, BLAST analysis and COGs (Clusters of Orthologous Groups of proteins). This approach detects the kinase (catalytic) domain structure and also the recently described FAT and FATC motifs.


Asunto(s)
Antihelmínticos/química , Diseño de Fármacos , Inhibidores Enzimáticos/química , Genoma de los Helmintos , Fosfatidilinositol 3-Quinasas/clasificación , Schistosoma mansoni/enzimología , Secuencia de Aminoácidos , Animales , Antihelmínticos/farmacología , Biología Computacional , Inhibidores Enzimáticos/farmacología , Datos de Secuencia Molecular , Fosfatidilinositol 3-Quinasas/química , Fosfatidilinositol 3-Quinasas/genética , Inhibidores de las Quinasa Fosfoinosítidos-3 , Filogenia , Schistosoma mansoni/genética , Análisis de Secuencia de ADN
13.
Biochem Biophys Res Commun ; 390(3): 963-70, 2009 Dec 18.
Artículo en Inglés | MEDLINE | ID: mdl-19852933

RESUMEN

Phosphatidylinositol (PI) kinases are at the heart of one of the major pathways of intracellular signal transduction. Herein, we present the first report on a survey made by similarity searches against the five human pathogenic trypanosomatids Trypanosoma brucei, Trypanosoma cruzi, Leishmania major, Leishmania braziliensis and Leishmania infantum genomes available to date for phosphatidylinositol- and related-kinases (TryPIKs). In addition to generating a panel called "The TryPIKinome", we propose a model of signaling pathways for these TryPIKs. The involvement of TryPIKs in fundamental pathways, such as intracellular signal transduction and host invasion processes, makes the study of TryPIKs an important area for further inquiry. New subtype-specific inhibitors are expected to work on individual members of the PIK family and, therefore, can presumably neutralize trypanosomatid invasion processes.


Asunto(s)
1-Fosfatidilinositol 4-Quinasa/clasificación , Diseño de Fármacos , Inhibidores Enzimáticos/química , Tripanocidas/química , Trypanosomatina/enzimología , 1-Fosfatidilinositol 4-Quinasa/antagonistas & inhibidores , 1-Fosfatidilinositol 4-Quinasa/genética , Secuencia de Aminoácidos , Androstadienos/química , Androstadienos/farmacología , Autofagia , Membrana Celular/enzimología , Citocinesis/efectos de los fármacos , Inhibidores Enzimáticos/aislamiento & purificación , Inhibidores Enzimáticos/farmacología , Humanos , Leishmania braziliensis/efectos de los fármacos , Leishmania braziliensis/enzimología , Leishmania braziliensis/crecimiento & desarrollo , Leishmania infantum/efectos de los fármacos , Leishmania infantum/enzimología , Leishmania infantum/crecimiento & desarrollo , Leishmania major/efectos de los fármacos , Leishmania major/enzimología , Leishmania major/crecimiento & desarrollo , Lisina/genética , Datos de Secuencia Molecular , Filogenia , Tripanocidas/aislamiento & purificación , Tripanocidas/farmacología , Trypanosoma brucei brucei/efectos de los fármacos , Trypanosoma brucei brucei/enzimología , Trypanosoma brucei brucei/crecimiento & desarrollo , Trypanosoma cruzi/efectos de los fármacos , Trypanosoma cruzi/enzimología , Trypanosoma cruzi/crecimiento & desarrollo , Trypanosomatina/efectos de los fármacos , Trypanosomatina/crecimiento & desarrollo , Wortmanina
14.
Microbes Infect ; 21(10): 485-489, 2019 12.
Artículo en Inglés | MEDLINE | ID: mdl-31247328

RESUMEN

Cell invasion by Trypanosoma cruzi extracellular amastigotes involves different signaling pathways to induce phagocytosis-like mechanisms. Previous works indicated that PI3K/Akt, Src and Erk might be involved in EA invasion; however, participation of these molecules in this process remains elusive. Here, we observed that EA activated Akt, Erk but not Src. Interference of EA invasion with specific inhibitors corroborated this observation. Our results show that EA is capable of selectively triggering complex signaling pathways. Activation of PI3K/Akt and Erk, kinases related to actin cytoskeleton rearrangement and phagocytosis, reinforces the idea that T. cruzi EA subverts the phagocytic machinery during invasion.


Asunto(s)
Enfermedad de Chagas/metabolismo , Quinasas MAP Reguladas por Señal Extracelular/metabolismo , Proteínas Proto-Oncogénicas c-akt/metabolismo , Transducción de Señal , Trypanosoma cruzi/fisiología , Enfermedad de Chagas/parasitología , Inhibidores Enzimáticos/farmacología , Quinasas MAP Reguladas por Señal Extracelular/antagonistas & inhibidores , Células HeLa , Humanos , Inhibidores de las Quinasa Fosfoinosítidos-3/farmacología , Fosforilación/efectos de los fármacos , Proteínas Proto-Oncogénicas c-akt/antagonistas & inhibidores , Transducción de Señal/efectos de los fármacos
15.
Artículo en Inglés | MEDLINE | ID: mdl-30042928

RESUMEN

The mevalonate pathway is an essential part of isoprenoid biosynthesis leading to production of a diverse class of >30,000 biomolecules including cholesterol, heme, and all steroid hormones. In trypanosomatids, the mevalonate pathway also generates dolichols, which play an essential role in construction of glycosylphosphatidylinositol (GPI) molecules that anchor variable surface proteins (VSGs) to the plasma membrane. Isoprenoid biosynthesis involves one of the most highly regulated enzymes in nature, 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR), which catalyzes the conversion of HMG-CoA to mevalonic acid. The enzyme mevalonate kinase (MVK) subsequently converts mevalonic acid to 5-phosphomevalonic acid. Trypanosoma evansi is a flagellate protozoan parasite that causes the disease "Surra" in domesticated large mammals, with great economic impact. T. evansi has only a trypomastigote bloodstream form and requires constant modification of the variant surface glycoprotein (VSG) coat for protection against the host immune system. We identified MVK of T. evansi (termed TeMVK) and performed a preliminary characterization at molecular, biochemical, and cellular levels. TeMVK from parasite extract displayed molecular weight ~36 kDa, colocalized with aldolase (a glycosomal marker enzyme) in glycosomes, and is structurally similar to Leishmania major MVK. Interestingly, the active form of TeMVK is the tetrameric oligomer form, in contrast to other MVKs in which the dimeric form is active. Despite lacking organized mitochondria, T. evansi synthesizes both HMGCR transcripts and protein. Both MVK and HMGCR are expressed in T. evansi during the course of infection in animals, and therefore are potential targets for therapeutic drug design.


Asunto(s)
Ácido Mevalónico/análogos & derivados , Ácido Mevalónico/metabolismo , Fosfotransferasas (Aceptor de Grupo Alcohol)/genética , Fosfotransferasas (Aceptor de Grupo Alcohol)/metabolismo , Trypanosoma/enzimología , Perfilación de la Expresión Génica , Microcuerpos/enzimología , Peso Molecular , Fosfotransferasas (Aceptor de Grupo Alcohol)/química , Fosfotransferasas (Aceptor de Grupo Alcohol)/aislamiento & purificación , Multimerización de Proteína
16.
Mol Biochem Parasitol ; 154(2): 134-40, 2007 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-17568698

RESUMEN

Single nucleotide polymorphism (SNP) markers have been shown to be useful in genetic investigations of medically important parasites and their hosts. In this paper, we describe the prediction and validation of SNPs in ESTs of Schistosoma mansoni. We used 107,417 public sequences of S. mansoni and identified 15,614 high-quality candidate SNPs in 12,184 contigs. The presence of predicted SNPs was observed in well characterized antigens and vaccine candidates such as those coding for myosin; Sm14 and Sm23; cathepsin B and triosephosphate isomerase (TPI). Additionally, SNPs were experimentally validated for the cathepsin B. A comparative model of the S. mansoni cathepsin B was built for predicting the possible consequences of amino acid substitutions on the protein structure. An analysis of the substitutions indicated that the amino acids were mostly located on the surface of the molecule, and we found no evidence for a significant conformational change of the enzyme. However, at least one of the substitutions could result in a structural modification of an epitope.


Asunto(s)
Schistosoma mansoni/genética , Animales , Antígenos Helmínticos/genética , Catepsina B/química , Catepsina B/genética , Proteínas de Transporte de Ácidos Grasos/genética , Genes de Helminto/genética , Proteínas del Helminto/genética , Modelos Moleculares , Miosinas/genética , Polimorfismo de Nucleótido Simple , Triosa-Fosfato Isomerasa/genética
17.
Front Microbiol ; 8: 1453, 2017.
Artículo en Inglés | MEDLINE | ID: mdl-28824583

RESUMEN

Inositol phosphorylceramide (IPC), the major sphingolipid in the genus Leishmania but not found in mammals, is considered a potentially useful target for chemotherapy against leishmaniasis. Leishmania (Viannia) braziliensis is endemic in Latin America and causes American tegumentary leishmaniasis. We demonstrated that IPCs are localized internally in parasites, using a specific monoclonal antibody. Treatment with 5 µM myriocin (a serine palmitoyltransferase inhibitor) rendered promastigotes 8-fold less infective than controls in experimental hamster infection, as determined by number of parasites per inguinal lymph node after 8 weeks infection, suggesting the importance of parasite IPC or sphingolipid derivatives in parasite infectivity or survival in the host. IPC was isolated from promastigotes of three L. (V.) braziliensis strains and analyzed by positive- and negative-ion ESI-MS. The major IPC ions were characterized as eicosasphinganine and eicosasphingosine. Negative-ion ESI-MS revealed IPC ion species at m/z 778.6 (d20:1/14:0), 780.6 (d20:0/14:0), 796.6 (t20:0/14:0), 806.6 (d20:1/16:0), and 808.6 (d20:0/16:0). IPCs isolated from L. (V.) braziliensis and L. (L.) major showed significant differences in IPC ceramide composition. The major IPC ion from L. (L.) major, detected in negative-ion ESI-MS at m/z 780.6, was composed of ceramide d16:1/18:0. Our results suggest that sphingosine synthase (also known as serine palmitoyltransferase; SPT) in L. (V.) braziliensis is responsible for synthesis of a long-chain base of 20 carbons (d20), whereas SPT in L. (L.) major synthesizes a 16-carbon long-chain base (d16). A phylogenetic tree based on SPT proteins was constructed by analysis of sequence homologies in species of the Leishmania and Viannia subgenera. Results indicate that SPT gene position in L. (V.) braziliensis is completely separated from that of members of subgenus Leishmania, including L. (L.) major, L. (L.) infantum, and L. (L.) mexicana. Our findings clearly demonstrate sphingoid base differences between L. (V.) braziliensis and members of subgenus Leishmania, and are relevant to future development of more effective targeted anti-leishmaniasis drugs.

18.
Front Microbiol ; 8: 1235, 2017.
Artículo en Inglés | MEDLINE | ID: mdl-28769876

RESUMEN

In its hyphal form, Candida albicans invades epithelial and endothelial cells by two distinct mechanisms: active penetration and induced endocytosis. The latter is dependent on a reorganization of the host cytoskeleton (actin/cortactin recruitment), whilst active penetration does not rely on the host's cellular machinery. The first obstacle for the fungus to reach deep tissues is the epithelial barrier and this interaction is crucial for commensal growth, fungal pathogenicity and host defense. This study aimed to characterize in vitro epithelial HeLa cell invasion by four different isolates of C. albicans with distinct clinical backgrounds, including a C. albicans SC5314 reference strain. All isolates invaded HeLa cells, recruited actin and cortactin, and induced the phosphorylation of both Src-family kinases (SFK) and cortactin. Curiously, L3881 isolated from blood culture of a patient exhibited the highest resistance to oxidative stress, although this isolate showed reduced hyphal length and displayed the lowest cell damage and invasion rates. Collectively, these data suggest that the ability of C. albicans to invade HeLa cells, and to reach and adapt to the host's blood, including resistance to oxidative stress, may be independent of hyphal length.

19.
Artículo en Inglés | MEDLINE | ID: mdl-16901822

RESUMEN

Macromolecular nuclear import is an energy-and signal-dependent process. The best characterized type of nuclear import consists of proteins carrying the classical NLS that is mediated by the heterodimeric receptor importin alpha/beta. Spliceosomal snRNPs U1, U2, U4, and U5 nuclear import depend both on the 5' terminal m3G (trimethylguanosine) cap structure of the U snRNA and the Sm core domain. Snurportin 1 recognizes the m3G-cap structure of m3G-capped U snRNPs. In this report, we show how a synthesized trimethylguanosine nucleoside affects the binding of Snurportin 1 to m3G-capped U1 snRNA in a UV-cross-linking assay. The data indicated that TMG nucleoside is an essential component required in the recognition by Snurportin 1, thus suggesting that interaction of Snurportin 1 with U1 snRNA is not strictly dependent on the presence of the whole cap structure, but rather on the presence of the TMG nucleoside structure. These results indicate that the free nucleoside TMG could be a candidate to be an inhibitor of the interaction between Snurportin 1 and U snRNAs. We also show the behavior of free TMG nucleoside in in vitro U snRNPs nuclear import.


Asunto(s)
Guanosina/análogos & derivados , Nucleósidos/farmacología , Proteínas de Unión a Caperuzas de ARN/efectos de los fármacos , Caperuzas de ARN/efectos de los fármacos , ARN Nuclear Pequeño/efectos de los fármacos , Receptores Citoplasmáticos y Nucleares/efectos de los fármacos , Animales , Transporte Biológico/efectos de los fármacos , Células Cultivadas , Guanosina/farmacología , Humanos , Nucleósidos/química , Proteínas de Unión a Caperuzas de ARN/metabolismo , Proteínas de Unión a Caperuzas de ARN/efectos de la radiación , Caperuzas de ARN/metabolismo , Caperuzas de ARN/efectos de la radiación , ARN Nuclear Pequeño/metabolismo , ARN Nuclear Pequeño/efectos de la radiación , Receptores Citoplasmáticos y Nucleares/metabolismo , Receptores Citoplasmáticos y Nucleares/efectos de la radiación , Rayos Ultravioleta
20.
Front Microbiol ; 7: 388, 2016.
Artículo en Inglés | MEDLINE | ID: mdl-27065960

RESUMEN

Chagas disease is one of the prevalent neglected tropical diseases, affecting at least 6-7 million individuals in Latin America. It is caused by the protozoan parasite Trypanosoma cruzi, which is transmitted to vertebrate hosts by blood-sucking insects. After infection, the parasite invades and multiplies in the myocardium, leading to acute myocarditis that kills around 5% of untreated individuals. T. cruzi secretes proteins that manipulate multiple host cell signaling pathways to promote host cell invasion. The primary secreted lysosomal peptidase in T. cruzi is cruzipain, which has been shown to modulate the host immune response. Cruzipain hinders macrophage activation during the early stages of infection by interrupting the NF-kB P65 mediated signaling pathway. This allows the parasite to survive and replicate, and may contribute to the spread of infection in acute Chagas disease. Another secreted protein P21, which is expressed in all of the developmental stages of T. cruzi, has been shown to modulate host phagocytosis signaling pathways. The parasite also secretes soluble factors that exert effects on host extracellular matrix, such as proteolytic degradation of collagens. Finally, secreted phospholipase A from T. cruzi contributes to lipid modifications on host cells and concomitantly activates the PKC signaling pathway. Here, we present a brief review of the interaction between secreted proteins from T. cruzi and the host cells, emphasizing the manipulation of host signaling pathways during invasion.

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