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1.
Respir Res ; 25(1): 211, 2024 May 18.
Artículo en Inglés | MEDLINE | ID: mdl-38762736

RESUMEN

BACKGROUND: Bronchiectasis is a condition characterized by abnormal and irreversible bronchial dilation resulting from lung tissue damage and can be categorized into two main groups: cystic fibrosis (CF) and non-CF bronchiectasis (NCFB). Both diseases are marked by recurrent infections, inflammatory exacerbations, and lung damage. Given that infections are the primary drivers of disease progression, characterization of the respiratory microbiome can shed light on compositional alterations and susceptibility to antimicrobial drugs in these cases compared to healthy individuals. METHODS: To assess the microbiota in the two studied diseases, 35 subjects were recruited, comprising 10 NCFB and 13 CF patients and 12 healthy individuals. Nasopharyngeal swabs and induced sputum were collected, and total DNA was extracted. The DNA was then sequenced by the shotgun method and evaluated using the SqueezeMeta pipeline and R. RESULTS: We observed reduced species diversity in both disease cohorts, along with distinct microbial compositions and profiles of antimicrobial resistance genes, compared to healthy individuals. The nasopharynx exhibited a consistent microbiota composition across all cohorts. Enrichment of members of the Burkholderiaceae family and an increased Firmicutes/Bacteroidetes ratio in the CF cohort emerged as key distinguishing factors compared to NCFB group. Staphylococcus aureus and Prevotella shahii also presented differential abundance in the CF and NCFB cohorts, respectively, in the lower respiratory tract. Considering antimicrobial resistance, a high number of genes related to antibiotic efflux were detected in both disease groups, which correlated with the patient's clinical data. CONCLUSIONS: Bronchiectasis is associated with reduced microbial diversity and a shift in microbial and resistome composition compared to healthy subjects. Despite some similarities, CF and NCFB present significant differences in microbiome composition and antimicrobial resistance profiles, suggesting the need for customized management strategies for each disease.


Asunto(s)
Bronquiectasia , Fibrosis Quística , Microbiota , Humanos , Bronquiectasia/microbiología , Bronquiectasia/tratamiento farmacológico , Bronquiectasia/diagnóstico , Fibrosis Quística/microbiología , Fibrosis Quística/tratamiento farmacológico , Fibrosis Quística/diagnóstico , Masculino , Femenino , Microbiota/fisiología , Microbiota/efectos de los fármacos , Adulto , Persona de Mediana Edad , Esputo/microbiología , Adulto Joven , Estudios de Cohortes , Anciano
2.
Fungal Genet Biol ; 165: 103780, 2023 03.
Artículo en Inglés | MEDLINE | ID: mdl-36780981

RESUMEN

Cryptococcus gattii is one of the etiological agents of cryptococcosis. To achieve a successful infection, C. gattii cells must overcome the inhospitable host environment and deal with the highly specialized immune system and poor nutrients availability. Inside the host, C. gattii uses a diversified set of tools to maintain homeostasis and establish infection, such as the expression of remarkable and diverse heat shock proteins (Hsps). Grouped by molecular weight, little is known about the Hsp12 subset in pathogenic fungi. In this study, the function of the C. gattii HSP12.1 and HSP12.2 genes was characterized. Both genes were upregulated during murine infection and heat shock. The hsp12.1 Δ null mutant cells were sensitive to plasma membrane and oxidative stressors. Moreover, HSP12 deletion induced C. gattii reactive oxygen species (ROS) accumulation associated with a differential expression pattern of oxidative stress-responsive genes compared to the wild type strain. Apart from these findings, the deletion of the paralog gene HSP12.2 did not lead to any detectable phenotype. Additionally, the double-deletion mutant strain hsp12.1 Δ /hsp12.2 Δ presented a similar phenotype to the single-deletion mutant hsp12.1 Δ, suggesting a minor participation of Hsp12.2 in these processes. Furthermore, HSP12.1 disruption remarkably affected C. gattii virulence and phagocytosis by macrophages in an invertebrate model of infection, demonstrating its importance for C. gattii pathogenicity.


Asunto(s)
Criptococosis , Cryptococcus gattii , Proteínas de Choque Térmico Pequeñas , Animales , Ratones , Criptococosis/microbiología , Cryptococcus gattii/genética , Proteínas de Choque Térmico Pequeñas/metabolismo , Fagocitosis , Virulencia
3.
Genomics ; 113(2): 805-814, 2021 03.
Artículo en Inglés | MEDLINE | ID: mdl-33529779

RESUMEN

Cryptococcus gattii is one of the causes of cryptococcosis, a life-threatening disease generally characterized by pneumonia and/or meningitis. Zinc is an essential element for life, being required for the activity of many proteins with catalytic and structural roles. Here, we characterize ZRG1 (zinc-related gene 1), which codes a product involved in zinc metabolism. Transcriptional profiling revealed that zinc availability regulated the expression of ZRG1, and its null mutants demonstrated impaired growth in zinc- and nitrogen-limiting conditions. Moreover, zrg1 strains displayed alterations in the expression of the zinc homeostasis-related genes ZAP1 and ZIP1. Notably, cryptococcal cells lacking Zrg1 displayed upregulation of autophagy-like phenotypes. Despite no differences were detected in the classical virulence-associated traits; cryptococcal cells lacking ZRG1 displayed decreased capacity for survival inside macrophages and attenuated virulence in an invertebrate model. Together, these results indicate that ZRG1 plays an important role in proper zinc metabolism, and is necessary for cryptococcal fitness and virulence.


Asunto(s)
Proteínas de Transporte de Catión/genética , Cryptococcus gattii/genética , Proteínas Fúngicas/genética , Animales , Autofagia , Proteínas de Transporte de Catión/metabolismo , Cryptococcus gattii/metabolismo , Cryptococcus gattii/patogenicidad , Proteínas Fúngicas/metabolismo , Ratones , Mutación , Células RAW 264.7 , Zinc/metabolismo
4.
BMC Genomics ; 22(1): 371, 2021 May 20.
Artículo en Inglés | MEDLINE | ID: mdl-34016042

RESUMEN

BACKGROUND: Brazil is the third country most affected by Coronavirus disease-2019 (COVID-19), but viral evolution in municipality resolution is still poorly understood in Brazil and it is crucial to understand the epidemiology of viral spread. We aimed to track molecular evolution and spread of Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in Esteio (Southern Brazil) using phylogenetics and phylodynamics inferences from 21 new genomes in global and regional context. Importantly, the case fatality rate (CFR) in Esteio (3.26%) is slightly higher compared to the Rio Grande do Sul (RS) state (2.56%) and the entire Brazil (2.74%). RESULTS: We provided a comprehensive view of mutations from a representative sampling from May to October 2020, highlighting two frequent mutations in spike glycoprotein (D614G and V1176F), an emergent mutation (E484K) in spike Receptor Binding Domain (RBD) characteristic of the B.1.351 and P.1 lineages, and the adjacent replacement of 2 amino acids in Nucleocapsid phosphoprotein (R203K and G204R). E484K was found in two genomes from mid-October, which is the earliest description of this mutation in Southern Brazil. Lineages containing this substitution must be subject of intense surveillance due to its association with immune evasion. We also found two epidemiologically-related clusters, including one from patients of the same neighborhood. Phylogenetics and phylodynamics analysis demonstrates multiple introductions of the Brazilian most prevalent lineages (B.1.1.33 and B.1.1.248) and the establishment of Brazilian lineages ignited from the Southeast to other Brazilian regions. CONCLUSIONS: Our data show the value of correlating clinical, epidemiological and genomic information for the understanding of viral evolution and its spatial distribution over time. This is of paramount importance to better inform policy making strategies to fight COVID-19.


Asunto(s)
COVID-19 , SARS-CoV-2 , Brasil/epidemiología , Genoma Viral , Genómica , Humanos
5.
Genet Mol Biol ; 44(3): e20200390, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-34352067

RESUMEN

Cryptococcus neoformans and Cryptococcus gattii are the etiological agents of cryptococcosis, a high mortality disease. The development of such disease depends on the interaction of fungal cells with macrophages, in which they can reside and replicate. In order to dissect the molecular mechanisms by which cryptococcal cells modulate the activity of macrophages, a genome-scale comparative analysis of transcriptional changes in macrophages exposed to Cryptococcus spp. was conducted. Altered expression of nearly 40 genes was detected in macrophages exposed to cryptococcal cells. The major processes were associated with the mTOR pathway, whose associated genes exhibited decreased expression in macrophages incubated with cryptococcal cells. Phosphorylation of p70S6K and GSK-3ß was also decreased in macrophages incubated with fungal cells. In this way, Cryptococci presence could drive the modulation of mTOR pathway in macrophages possibly to increase the survival of the pathogen.

6.
Fungal Genet Biol ; 144: 103438, 2020 11.
Artículo en Inglés | MEDLINE | ID: mdl-32738289

RESUMEN

Cryptococcus gattii is an etiologic agent of cryptococcosis, a potentially fatal disease that affects humans and animals. The successful infection of mammalian hosts by cryptococcal cells relies on their ability to infect and survive in macrophages. Such phagocytic cells present a hostile environment to intracellular pathogens via the production of reactive nitrogen and oxygen species, as well as low pH and reduced nutrient bioavailability. To overcome the low-metal environment found during infection, fungal pathogens express high-affinity transporters, including members of the ZIP family. Previously, we determined that functional zinc uptake driven by Zip1 and Zip2 is necessary for full C.gattiivirulence. Here, we characterized the ZIP3 gene of C. gattii, an ortholog of the Saccharomyces cerevisiae ATX2, which codes a manganese transporter localized to the membrane of the Golgi apparatus. Cryptococcal cells lacking Zip3 were tolerant to toxic concentrations of manganese and had imbalanced expression of intracellular metal transporters, such as the vacuolar Pmc1 and Vcx1, as well as the Golgi Pmr1. Moreover, null mutants of the ZIP3 gene displayed higher sensitivity to reactive oxygen species (ROS) and substantial alteration in the expression of ROS-detoxifying enzyme-coding genes. In line with these phenotypes, cryptococcal cells displayed decreased virulence in a non-vertebrate model of cryptococcosis. Furthermore, we found that the ZIP3 null mutant strain displayed decreased melanization and secretion of the major capsular component glucuronoxylomannan, as well as an altered extracellular vesicle dimensions profile. Collectively, our data suggest that Zip3 activity impacts the physiology, and consequently, several virulence traits of C. gattii.


Asunto(s)
Proteínas de Transporte de Catión/genética , Cryptococcus gattii/genética , Proteínas de Saccharomyces cerevisiae/genética , Ubiquitina-Proteína Ligasas/genética , Animales , Criptococosis/genética , Criptococosis/microbiología , Criptococosis/patología , Cryptococcus gattii/metabolismo , Cryptococcus gattii/patogenicidad , Humanos , Macrófagos/metabolismo , Manganeso/metabolismo , Fenotipo , Especies Reactivas de Oxígeno/metabolismo , Virulencia/genética
7.
Curr Top Microbiol Immunol ; 422: 31-43, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-30203395

RESUMEN

Pathogenic species of Cryptococcus kill approximately 200,000 people each year. The most important virulence mechanism of C. neoformans and C. gattii, the causative agents of human and animal cryptococcosis, is the ability to form a polysaccharide capsule. Acapsular mutants of C. neoformans are avirulent in mice models of infection, and extracellularly released capsular polysaccharides are deleterious to the immune system. The principal capsular component in the Cryptococcus genus is a complex mannan substituted with xylosyl and glucuronyl units, namely glucuronoxylomannan (GXM). The second most abundant component of the cryptococcal capsule is a galactan with multiple glucuronyl, xylosyl, and mannosyl substitutions, namely glucuronoxylomannogalactan (GXMGal). The literature about the structure and functions of these two polysaccharides is rich, and a number of comprehensive reviews on this topic are available. Here, we focus our discussion on the less explored glycan components associated with the cryptococcal capsule, including mannoproteins and chitin-derived molecules. These glycans were selected for discussion on the basis that i) they have been consistently detected not only in the cell wall but also within the cryptococcal capsular network and ii) they have functions that impact immunological and/or pathogenic mechanisms in the Cryptococcus genus. The reported functions of these molecules strongly indicate that the biological roles of the cryptococcal capsule go far beyond the well-known properties of GXM and GXMGal.


Asunto(s)
Cryptococcus neoformans/química , Cryptococcus neoformans/citología , Polisacáridos/análisis , Polisacáridos/metabolismo , Animales , Pared Celular/química , Criptococosis/microbiología , Cryptococcus neoformans/patogenicidad , Humanos , Virulencia
8.
FEMS Yeast Res ; 19(1)2019 01 01.
Artículo en Inglés | MEDLINE | ID: mdl-30418573

RESUMEN

Melanin formation is a promising target for antifungal development. We screened a collection of 727 compounds that were previously approved for clinical use in humans for inhibition of pigmentation in Cryptococcus gattii, a lethal fungal pathogen that causes damage to both immunocompetent and immunocompromised hosts. The pyrimidine analogues flucytosine (5-fluorocytosine [5-FC]), 5-fluorouracil (5-FU) and carmofur were identified as efficient inhibitors of pigmentation in the C. gattii model. Since melanin synthesis is enzymatically catalyzed by laccase in Cryptococcus, we investigated whether inhibition of pigmentation by the pyrimidine analogues was laccase-mediated. Enzyme activity and expression of LAC genes were not involved in the effects of the pyrimidine analogues, suggesting alternative cellular targets for inhibition of pigmentation. To address this hypothesis, we screened a collection of approximately 8000 mutants of C. gattii that were produced by insertional mutation after incubation with Agrobacterium tumefaciens and identified a gene product required for the anti-pigmentation activity of 5-FC as a beta-DNA polymerase. Reduced expression of this gene affected capsule formation and urease activity, suggesting essential roles in the cryptococcal physiology. These results demonstrate a previously unknown antifungal activity of 5-FC and reveal a promising target for the development of novel antifungals.


Asunto(s)
Antifúngicos/farmacología , Cryptococcus gattii/efectos de los fármacos , Melaninas/antagonistas & inhibidores , Melaninas/biosíntesis , Cryptococcus gattii/genética , Análisis Mutacional de ADN , Evaluación Preclínica de Medicamentos , Flucitosina/farmacología , Fluorouracilo/análogos & derivados , Fluorouracilo/farmacología , Pruebas Genéticas , Mutagénesis Insercional
9.
Cell Microbiol ; 20(2)2018 02.
Artículo en Inglés | MEDLINE | ID: mdl-29113016

RESUMEN

Cryptococcus neoformans is a basidiomycetous yeast and the cause of cryptococcosis in immunocompromised individuals. The most severe form of the disease is meningoencephalitis, which is one of the leading causes of death in HIV/AIDS patients. In order to access the central nervous system, C. neoformans relies on the activity of certain virulence factors such as urease, which allows transmigration through the blood-brain barrier. In this study, we demonstrate that the calcium transporter Pmc1 enables C. neoformans to penetrate the central nervous system, because the pmc1 null mutant failed to infect and to survive within the brain parenchyma in a murine systemic infection model. To investigate potential alterations in transmigration pathways in these mutants, global expression profiling of the pmc1 mutant strain was undertaken, and genes associated with urease, the Ca2+ -calcineurin pathway, and capsule assembly were identified as being differentially expressed. Also, a decrease in urease activity was observed in the calcium transporter null mutants. Finally, we demonstrate that the transcription factor Crz1 regulates urease activity and that the Ca2+ -calcineurin signalling pathway positively controls the transcription of calcium transporter genes and factors related to transmigration.


Asunto(s)
Sistema Nervioso Central/microbiología , Cryptococcus neoformans/metabolismo , Cryptococcus neoformans/patogenicidad , Proteínas Fúngicas/metabolismo , ATPasas Transportadoras de Calcio de la Membrana Plasmática/metabolismo , Animales , Transporte Biológico/fisiología , Barrera Hematoencefálica/metabolismo , Barrera Hematoencefálica/microbiología , Encéfalo/metabolismo , Encéfalo/microbiología , Calcineurina/metabolismo , Calcio/metabolismo , Línea Celular , Criptococosis/metabolismo , Criptococosis/microbiología , Modelos Animales de Enfermedad , Femenino , Células Endoteliales de la Vena Umbilical Humana , Humanos , Meningoencefalitis/metabolismo , Meningoencefalitis/microbiología , Ratones , Ratones Endogámicos BALB C , Vacuolas/metabolismo , Vacuolas/microbiología , Virulencia/fisiología , Factores de Virulencia/metabolismo
10.
BMC Genomics ; 18(1): 294, 2017 04 12.
Artículo en Inglés | MEDLINE | ID: mdl-28403818

RESUMEN

BACKGROUND: The absence of Argonaute genes in the fungal pathogen Cryptococcus gattii R265 and other VGII strains indicates that yeasts of this genotype cannot have a functional RNAi pathway, an evolutionarily conserved gene silencing mechanism performed by small RNAs. The success of the R265 strain as a pathogen that caused the Pacific Northwest and Vancouver Island outbreaks may imply that RNAi machinery loss could be beneficial under certain circumstances during evolution. As a result, a hypermutant phenotype would be created with high rates of genome retrotransposition, for instance. This study therefore aimed to evaluate in silicio the effect of retrotransposons and their control mechanisms by small RNAs on genomic stability and synteny loss of C. gattii R265 through retrotransposons sequence comparison and orthology analysis with other 16 C. gattii genomic sequences available. RESULTS: Retrotransposon mining identified a higher sequence count to VGI genotype compared to VGII, VGIII, and VGIV. However, despite the lower retrotransposon number, VGII exhibited increased synteny loss and genome rearrangement events. RNA-Seq analysis indicated highly expressed retrotransposons as well as sRNA production. CONCLUSIONS: Genome rearrangement and synteny loss may suggest a greater retrotransposon mobilization caused by RNAi pathway absence, but the effective presence of sRNAs that matches retrotransposon sequences means that an alternative retrotransposon silencing mechanism could be active in genomic integrity maintenance of C. gattii VGII strains.


Asunto(s)
Cryptococcus gattii/genética , ARN Interferente Pequeño/genética , Retroelementos , Análisis de Secuencia de ARN/métodos , Evolución Biológica , Simulación por Computador , Genotipo , Filogenia , ARN de Hongos/genética , Eliminación de Secuencia , Sintenía
11.
Am J Hum Biol ; 28(3): 381-6, 2016 05.
Artículo en Inglés | MEDLINE | ID: mdl-26458076

RESUMEN

OBJECTIVES: The aim of the present study was to evaluate the relationship between the rs9939609 fat mass and obesity-associated (FTO) polymorphism and cardiorespiratory fitness (CRF) with overweight/obesity outcomes in youth. METHODS: This study included 420 youths, comprising 211 boys and 209 girls aged 7-17. Overweight/obesity were evaluated by body mass index (BMI), waist circumference (WC), and the percentage of fat (PF) according to two skinfold thickness measurements. Genotyping of the rs9939609 polymorphism was conducted using real-time Polymerase Chain Reaction (PCR) utilizing TaqMan(®) probes, and CRF was evaluated through a 9-minute run/walk test, categorized as fit or unfit. Logistic regression was utilized to evaluate a possible association between the polymorphism and CRF, with three obesity indicators evaluated. RESULTS: Individuals with the genotype risk (AA) of FTO polymorphism rs9939609 showed higher prevalence of overweight/obesity, as evaluated by BMI (OR: 3.21; CI: 1.71-6.05), WC (OR: 2.59; CI: 1.35-4.97), and PF (OR: 2.59; CI: 1.36-4.92). Additionally, students with the AA genotype in the unfit model had a significant odds ratio for obesity (OR: 4.40; CI: 1.83-10.61 for BMI; OR: 3.54; CI: 1.58-7.96 for WC), whereas we did not observe associations between the AA genotype with BMI and WC using the fit model. Conversely, PF was associated with the AA genotype only in the fit model (OR: 3.24; CI: 1.26-8.34). CONCLUSIONS: This study demonstrated that the rs9939609 (FTO) polymorphism showed a relationship with obesity in the population studied and an interaction with CRF. Students with low levels of CRF and the AA genotype have a higher risk of being overweight/obese. This association was not found in students with higher levels of CRF. Am. J. Hum. Biol. 28:381-386, 2016. © 2015 Wiley Periodicals, Inc.


Asunto(s)
Dioxigenasa FTO Dependiente de Alfa-Cetoglutarato/genética , Capacidad Cardiovascular/fisiología , Obesidad Infantil/epidemiología , Polimorfismo Genético , Adolescente , Dioxigenasa FTO Dependiente de Alfa-Cetoglutarato/metabolismo , Brasil , Niño , Femenino , Humanos , Masculino , Obesidad Infantil/genética , Obesidad Infantil/fisiopatología , Prevalencia
13.
BMC Genomics ; 15: 822, 2014 Sep 29.
Artículo en Inglés | MEDLINE | ID: mdl-25263348

RESUMEN

BACKGROUND: Metarhizium anisopliae is an entomopathogenic fungus used in the biological control of some agricultural insect pests, and efforts are underway to use this fungus in the control of insect-borne human diseases. A large repertoire of proteins must be secreted by M. anisopliae to cope with the various available nutrients as this fungus switches through different lifestyles, i.e., from a saprophytic, to an infectious, to a plant endophytic stage. To further evaluate the predicted secretome of M. anisopliae, we employed genomic and transcriptomic analyses, coupled with phylogenomic analysis, focusing on the identification and characterization of secreted proteins. RESULTS: We determined the M. anisopliae E6 genome sequence and compared this sequence to other entomopathogenic fungi genomes. A robust pipeline was generated to evaluate the predicted secretomes of M. anisopliae and 15 other filamentous fungi, leading to the identification of a core of secreted proteins. Transcriptomic analysis using the tick Rhipicephalus microplus cuticle as an infection model during two periods of infection (48 and 144 h) allowed the identification of several differentially expressed genes. This analysis concluded that a large proportion of the predicted secretome coding genes contained altered transcript levels in the conditions analyzed in this study. In addition, some specific secreted proteins from Metarhizium have an evolutionary history similar to orthologs found in Beauveria/Cordyceps. This similarity suggests that a set of secreted proteins has evolved to participate in entomopathogenicity. CONCLUSIONS: The data presented represents an important step to the characterization of the role of secreted proteins in the virulence and pathogenicity of M. anisopliae.


Asunto(s)
Proteínas Fúngicas/genética , Genoma Fúngico , Metarhizium/genética , Animales , Hibridación Genómica Comparativa , Perfilación de la Expresión Génica , Interacciones Huésped-Patógeno/genética , Metarhizium/clasificación , Filogenia , Rhipicephalus/metabolismo , Rhipicephalus/microbiología , Análisis de Secuencia de ARN
14.
Fungal Genet Biol ; 60: 53-63, 2013 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-23954835

RESUMEN

The pathogenic yeast Cryptococcus neoformans secretes numerous proteins, such as heat shock proteins, by unconventional mechanisms during its interaction with host cells. Hsp70 is a conserved chaperone that plays important roles in various cellular processes, including the interaction of fungi with host immune cells. Here, we report that sera from individuals with cryptococcosis infection recognize a recombinant C. neoformans Hsp70 (Cn_rHsp70). Moreover, immunofluorescence assays using antibodies against Cn_rHsp70 revealed the localization of this protein at the cell surface mainly in association with the capsular network. We found that the addition of Cn_rHsp70 positively modulated the interaction of C. neoformans with human alveolar epithelial cells and decreased fungal killing by mouse macrophages, without affecting phagocytosis rates. Immunofluorescence analysis showed that there was a competitive association among the receptor, GXM and Cn_rHsp70, indicating that the Hsp70-binding sites in host cells appear to be shared by glucuronoxylomannan (GXM), the major capsular antigen in C. neoformans. Our observations suggest additional mechanisms by which Hsp70 influences the interaction of C. neoformans with host cells.


Asunto(s)
Cryptococcus neoformans/metabolismo , Proteínas HSP70 de Choque Térmico/metabolismo , Proteínas de la Membrana/metabolismo , Animales , Anticuerpos Antifúngicos/sangre , Anticuerpos Antifúngicos/inmunología , Sitios de Unión , Línea Celular , Criptococosis/inmunología , Cryptococcus neoformans/patogenicidad , Células Epiteliales/microbiología , Femenino , Técnica del Anticuerpo Fluorescente , Proteínas HSP70 de Choque Térmico/genética , Proteínas HSP70 de Choque Térmico/inmunología , Interacciones Huésped-Patógeno , Humanos , Macrófagos/inmunología , Ratones , Ratones Endogámicos BALB C , Fagocitosis/inmunología , Polisacáridos/metabolismo , Unión Proteica
15.
Fungal Genet Biol ; 60: 64-73, 2013 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-23608320

RESUMEN

The principal capsular component of Cryptococcus neoformans, glucuronoxylomannan (GXM), interacts with surface glycans, including chitin-like oligomers. Although the role of GXM in cryptococcal infection has been well explored, there is no information on how chitooligomers affect fungal pathogenesis. In this study, surface chitooligomers of C. neoformans were blocked through the use of the wheat germ lectin (WGA) and the effects on animal pathogenesis, interaction with host cells, fungal growth and capsule formation were analyzed. Treatment of C. neoformans cells with WGA followed by infection of mice delayed mortality relative to animals infected with untreated fungal cells. This observation was associated with reduced brain colonization by lectin-treated cryptococci. Blocking chitooligomers also rendered yeast cells less efficient in their ability to associate with phagocytes. WGA did not affect fungal viability, but inhibited GXM release to the extracellular space and capsule formation. In WGA-treated yeast cells, genes that are involved in capsule formation and GXM traffic had their transcription levels decreased in comparison with untreated cells. Our results suggest that cellular pathways required for capsule formation and pathogenic mechanisms are affected by blocking chitin-derived structures at the cell surface of C. neoformans. Targeting chitooligomers with specific ligands may reveal new therapeutic alternatives to control cryptococcosis.


Asunto(s)
Cryptococcus neoformans/patogenicidad , Cápsulas Fúngicas/metabolismo , Fagocitosis/efectos de los fármacos , Polisacáridos/metabolismo , Aglutininas del Germen de Trigo/farmacología , Animales , Encéfalo/microbiología , Quitina/metabolismo , Criptococosis/tratamiento farmacológico , Criptococosis/patología , Cryptococcus neoformans/crecimiento & desarrollo , Cryptococcus neoformans/metabolismo , Cápsulas Fúngicas/efectos de los fármacos , Macrófagos/efectos de los fármacos , Macrófagos/inmunología , Ratones , Ratones Endogámicos C57BL , Aglutininas del Germen de Trigo/metabolismo
16.
Virology ; 582: 1-11, 2023 05.
Artículo en Inglés | MEDLINE | ID: mdl-36989935

RESUMEN

SARS-CoV-2 is the virus responsible for the COVID-19 and has afflicted the world since the end of 2019. Different lineages have been discovered and the Gamma lineage, which started the second wave of infections, was first described in Brazil, one of the most affected countries by pandemic. Therefore, this study analyzed SARS-CoV-2 sequenced genomes from Esteio city in Rio Grande do Sul, Southern Brazil. We also comparatively analyzed genomes of the two first years of the pandemic from Rio Grande do Sul state for understanding their genomic and evolutionary patterns. The phylogenomic analysis showed monophyletic groups for Alpha, Gamma, Delta and Omicron, as well as for other circulating lineages in the state. Molecular evolutionary analysis identified several sites under adaptive selection in membrane and nucleocapsid proteins which could be related to a prevalent stabilizing effect on membrane protein structure, as well as majoritarily destabilizing effects on C-terminal nucleocapsid domain.


Asunto(s)
COVID-19 , SARS-CoV-2 , Humanos , SARS-CoV-2/genética , COVID-19/epidemiología , Brasil/epidemiología , Genómica , Evolución Molecular , Filogenia
17.
Mol Microbiol ; 81(1): 206-18, 2011 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-21542865

RESUMEN

Secretion of virulence factors is a critical mechanism for the establishment of cryptococcosis, a disease caused by the yeast pathogen Cryptococcus neoformans. One key virulence strategy of C. neoformans is the release of glucuronoxylomannan (GXM), a capsule-associated immune-modulatory polysaccharide that reaches the extracellular space through secretory vesicles. Golgi reassembly and stacking protein (GRASP) is required for unconventional protein secretion mechanisms in different eukaryotic cells, but its role in polysaccharide secretion is unknown. This study demonstrates that a C. neoformans functional mutant of a GRASP orthologue had attenuated virulence in an animal model of cryptococcosis, in comparison with wild-type (WT) and reconstituted cells. Mutant cells manifested altered Golgi morphology, failed to produce typical polysaccharide capsules and showed a reduced ability to secrete GXM both in vitro and during animal infection. Isolation of GXM from cultures of WT, reconstituted or mutant strains revealed that the GRASP orthologue mutant produced polysaccharides with reduced dimensions. The mutant was also more efficiently associated to and killed by macrophages than WT and reconstituted cells. These results demonstrate that GRASP, a protein involved in unconventional protein secretion, is also required for polysaccharide secretion and virulence in C. neoformans.


Asunto(s)
Cryptococcus neoformans/metabolismo , Cryptococcus neoformans/patogenicidad , Aparato de Golgi/metabolismo , Proteínas de la Membrana/metabolismo , Polisacáridos/metabolismo , Secuencia de Aminoácidos , Animales , Análisis por Conglomerados , Criptococosis/microbiología , Criptococosis/patología , Modelos Animales de Enfermedad , Eliminación de Gen , Prueba de Complementación Genética , Macrófagos/inmunología , Ratones , Ratones Endogámicos BALB C , Viabilidad Microbiana , Datos de Secuencia Molecular , Fagocitosis , Filogenia , Homología de Secuencia de Aminoácido , Análisis de Supervivencia , Virulencia
18.
Fungal Genet Biol ; 48(2): 192-9, 2011 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-20673806

RESUMEN

Nitrogen uptake and metabolism are essential to microbial growth. Gat1 belongs to a conserved family of zinc finger containing transcriptional regulators known as GATA-factors. These factors activate the transcription of Nitrogen Catabolite Repression (NCR) sensitive genes when preferred nitrogen sources are absent or limiting. Cryptococcus neoformans GAT1 is an ortholog to the Aspergillus nidulans AreA and Candida albicans GAT1 genes. In an attempt to define the function of this transcriptional regulator in C. neoformans, we generated null mutants (gat1Δ) of this gene. The gat1 mutant exhibited impaired growth on all amino acids tested as sole nitrogen sources, with the exception of arginine and proline. Furthermore, the gat1 mutant did not display resistance to rapamycin, an immunosuppressant drug that transiently mimics a low-quality nitrogen source. Gat1 is not required for C. neoformans survival during macrophage infection or for virulence in a mouse model of cryptococcosis. Microarray analysis allowed the identification of target genes that are regulated by Gat1 in the presence of proline, a poor and non-repressing nitrogen source. Genes involved in ergosterol biosynthesis, iron uptake, cell wall organization and capsule biosynthesis, in addition to NCR-sensitive genes, are Gat1-regulated in C. neoformans.


Asunto(s)
Cryptococcus neoformans/fisiología , Proteínas Fúngicas/metabolismo , Factores de Transcripción GATA/metabolismo , Regulación Fúngica de la Expresión Génica , Nitrógeno/metabolismo , Transactivadores/metabolismo , Animales , Aspergillus nidulans/genética , Candida albicans/genética , Criptococosis/microbiología , Cryptococcus neoformans/genética , Cryptococcus neoformans/crecimiento & desarrollo , Cryptococcus neoformans/metabolismo , Modelos Animales de Enfermedad , Femenino , Proteínas Fúngicas/genética , Factores de Transcripción GATA/genética , Eliminación de Gen , Perfilación de la Expresión Génica , Macrófagos/microbiología , Ratones , Ratones Endogámicos BALB C , Análisis por Micromatrices , Regulón , Homología de Secuencia de Aminoácido , Análisis de Supervivencia , Transactivadores/genética , Virulencia , Dedos de Zinc
19.
Eukaryot Cell ; 9(11): 1798-805, 2010 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-20889719

RESUMEN

Cryptococcus neoformans is an encapsulated yeast that causes a life-threatening meningoencephalitis in immunocompromised individuals. The ability to survive and proliferate at the human body temperature is an essential virulence attribute of this pathogen. This trait is controlled in part by the Ca²(+)-calcineurin pathway, which senses and utilizes cytosolic calcium for signaling. In the present study, the identification of the C. neoformans gene VCX1, which encodes a vacuolar calcium exchanger, is reported. The VCX1 knockout results in hypersensitivity to the calcineurin inhibitor cyclosporine A at 35°C, but not at 30°C. Furthermore, high concentrations of CaCl2 lead to growth inhibition of the vcx1 mutant strain only in the presence of cyclosporine A, indicating that Vcx1 acts in parallel with calcineurin. The loss of VCX1 does not influence cell wall integrity or capsule size but decreases secretion of the major capsular polysaccharide glucuronoxylomannan (GXM) in culture supernatants.Vcx1 also influences C. neoformans phagocytosis by murine macrophages and is required for full virulence in mice. Analysis of cellular distribution by confocal microscopy confirmed the vacuolar localization of Vcx1 in C. neoformans cells.


Asunto(s)
Antiportadores/metabolismo , Calcio/metabolismo , Cryptococcus neoformans/metabolismo , Cryptococcus neoformans/patogenicidad , Proteínas Fúngicas/metabolismo , Animales , Antiportadores/genética , Calcineurina/metabolismo , Línea Celular , Criptococosis/etiología , Cryptococcus neoformans/genética , Femenino , Proteínas Fúngicas/genética , Eliminación de Gen , Genes Fúngicos , Prueba de Complementación Genética , Humanos , Técnicas In Vitro , Macrófagos/inmunología , Macrófagos/microbiología , Ratones , Ratones Endogámicos BALB C , Mutación , Fagocitosis , Filogenia , Transducción de Señal , Vacuolas/metabolismo , Virulencia/genética , Virulencia/fisiología
20.
Microb Cell ; 8(5): 108-110, 2021 Apr 20.
Artículo en Inglés | MEDLINE | ID: mdl-33981763

RESUMEN

The regulation of virulence factor production and deployment is crucial for the establishment of microbial infection and subsequent pathogenesis. If these processes are not properly coordinated, the infecting pathogen is less likely to both survive the immune response and cause damage to the host. One key virulence factor of the opportunistic fungal pathogen Cryptococcus neoformans, which kills almost 200,000 people each year worldwide, is a polysaccharide capsule that surrounds the cell wall; this structure helps the fungal cells resist engulfment and elimination by host phagocytes. Another important virulence trait is the development of a giant (Titan) cell morphotype that increases fungal resistance to phagocytosis, oxidative stress, and antifungal treatment. We recently identified the transcription factor Pdr802 as essential for C. neoformans adaptation to and survival under host conditions both in vitro and in vivo (Reuwsaat et al., mBio, doi: 10.1128/mBio.03457-20). Cryptococci lacking Pdr802 display enlarged capsules and enhanced Titan cell production, along with dramatically reduced virulence in a mouse model of infection. These results demonstrate that more is not necessarily better when it comes to virulence factors. Instead, precise regulation of these traits, to avoid both under- and overexpression, is critical for the success of this pathogen as it faces the challenges imposed by the host environment.

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