RESUMO
Toxoplasmosis is a highly prevalent human disease, and virulent strains of this parasite emerge from wild biotopes. Here, we report on the potential of a histone deacetylase (HDAC) inhibitor we previously synthesized, named JF363, to act in vitro against a large panel of Toxoplasma strains, as well as against the liver and blood stages of Plasmodium parasites, the causative agents of malaria. In vivo administration of the drug significantly increases the survival of mice during the acute phase of infection by T. gondii, thus delaying its spreading. We further provide evidence of the compound's efficiency in controlling the formation of cysts in the brain of T. gondii-infected mice. A convincing docking of the JF363 compound in the active site of the five annotated ME49 T. gondii HDACs was performed by extensive sequence-structure comparison modeling. The resulting complexes show a similar mode of binding in the five paralogous structures and a quite similar prediction of affinities in the micromolar range. Altogether, these results pave the way for further development of this compound to treat acute and chronic toxoplasmosis. It also shows promise for the future development of anti-Plasmodium therapeutic interventions.
Assuntos
Parasitos , Plasmodium , Toxoplasma , Toxoplasmose , Animais , Inibidores de Histona Desacetilases/farmacologia , Inibidores de Histona Desacetilases/uso terapêutico , Histona Desacetilases , Camundongos , Toxoplasmose/tratamento farmacológicoRESUMO
Natural immunity or resistance to pathogens most often relies on the genetic make-up of the host. In a LEW rat model of refractoriness to toxoplasmosis, we previously identified on chromosome 10 the Toxo1 locus that directs toxoplasmosis outcome and controls parasite spreading by a macrophage-dependent mechanism. Now, we narrowed down Toxo1 to a 891 kb interval containing 29 genes syntenic to human 17p13 region. Strikingly, Toxo1 is included in a haplotype block strictly conserved among all refractory rat strains. The sequencing of Toxo1 in nine rat strains (5 refractory and 4 susceptible) revealed resistant-restricted conserved polymorphisms displaying a distribution gradient that peaks at the bottom border of Toxo1, and highlighting the NOD-like receptor, Nlrp1a, as a major candidate. The Nlrp1 inflammasome is known to trigger, upon pathogen intracellular sensing, pyroptosis programmed-cell death involving caspase-1 activation and cleavage of IL-1ß. Functional studies demonstrated that the Toxo1-dependent refractoriness in vivo correlated with both the ability of macrophages to restrict T. gondii growth and a T. gondii-induced death of intracellular parasites and its host macrophages. The parasite-induced cell death of infected macrophages bearing the LEW-Toxo1 alleles was found to exhibit pyroptosis-like features with ROS production, the activation of caspase-1 and IL1-ß secretion. The pharmacological inactivation of caspase-1 using YVAD and Z-VAD inhibitors prevented the death of both intravacuolar parasites and host non-permissive macrophages but failed to restore parasite proliferation. These findings demonstrated that the Toxo1-dependent response of rat macrophages to T. gondii infection may trigger two pathways leading to the control of parasite proliferation and the death of parasites and host macrophages. The NOD-like receptor NLRP1a/Caspase-1 pathway is the best candidate to mediate the parasite-induced cell death. These data represent new insights towards the identification of a major pathway of innate resistance to toxoplasmosis and the prediction of individual resistance.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Proteínas Reguladoras de Apoptose/metabolismo , Caspase 1/metabolismo , Loci Gênicos , Haplótipos , Macrófagos Peritoneais/metabolismo , Toxoplasma/metabolismo , Toxoplasmose/metabolismo , Animais , Caspase 1/genética , Inibidores de Caspase/farmacologia , Morte Celular/efeitos dos fármacos , Morte Celular/genética , Ativação Enzimática/efeitos dos fármacos , Ativação Enzimática/genética , Humanos , Inflamassomos/genética , Inflamassomos/metabolismo , Interleucina-1beta/genética , Interleucina-1beta/metabolismo , Macrófagos Peritoneais/parasitologia , Macrófagos Peritoneais/patologia , Camundongos , Oligopeptídeos/farmacologia , Ratos , Toxoplasmose/genética , Toxoplasmose/patologiaRESUMO
The analysis of the first plant genomes provided unexpected evidence for genome duplication events in species that had previously been considered as true diploids on the basis of their genetics. These polyploidization events may have had important consequences in plant evolution, in particular for species radiation and adaptation and for the modulation of functional capacities. Here we report a high-quality draft of the genome sequence of grapevine (Vitis vinifera) obtained from a highly homozygous genotype. The draft sequence of the grapevine genome is the fourth one produced so far for flowering plants, the second for a woody species and the first for a fruit crop (cultivated for both fruit and beverage). Grapevine was selected because of its important place in the cultural heritage of humanity beginning during the Neolithic period. Several large expansions of gene families with roles in aromatic features are observed. The grapevine genome has not undergone recent genome duplication, thus enabling the discovery of ancestral traits and features of the genetic organization of flowering plants. This analysis reveals the contribution of three ancestral genomes to the grapevine haploid content. This ancestral arrangement is common to many dicotyledonous plants but is absent from the genome of rice, which is a monocotyledon. Furthermore, we explain the chronology of previously described whole-genome duplication events in the evolution of flowering plants.
Assuntos
Evolução Molecular , Genoma de Planta/genética , Poliploidia , Vitis/classificação , Vitis/genética , Arabidopsis/genética , DNA Intergênico/genética , Éxons/genética , Genes de Plantas/genética , Íntrons/genética , Cariotipagem , MicroRNAs/genética , Dados de Sequência Molecular , Oryza/genética , Populus/genética , RNA de Plantas/genética , RNA de Transferência/genética , Análise de Sequência de DNARESUMO
BACKGROUND: Melon (Cucumis melo), an economically important vegetable crop, belongs to the Cucurbitaceae family which includes several other important crops such as watermelon, cucumber, and pumpkin. It has served as a model system for sex determination and vascular biology studies. However, genomic resources currently available for melon are limited. RESULT: We constructed eleven full-length enriched and four standard cDNA libraries from fruits, flowers, leaves, roots, cotyledons, and calluses of four different melon genotypes, and generated 71,577 and 22,179 ESTs from full-length enriched and standard cDNA libraries, respectively. These ESTs, together with ~35,000 ESTs available in public domains, were assembled into 24,444 unigenes, which were extensively annotated by comparing their sequences to different protein and functional domain databases, assigning them Gene Ontology (GO) terms, and mapping them onto metabolic pathways. Comparative analysis of melon unigenes and other plant genomes revealed that 75% to 85% of melon unigenes had homologs in other dicot plants, while approximately 70% had homologs in monocot plants. The analysis also identified 6,972 gene families that were conserved across dicot and monocot plants, and 181, 1,192, and 220 gene families specific to fleshy fruit-bearing plants, the Cucurbitaceae family, and melon, respectively. Digital expression analysis identified a total of 175 tissue-specific genes, which provides a valuable gene sequence resource for future genomics and functional studies. Furthermore, we identified 4,068 simple sequence repeats (SSRs) and 3,073 single nucleotide polymorphisms (SNPs) in the melon EST collection. Finally, we obtained a total of 1,382 melon full-length transcripts through the analysis of full-length enriched cDNA clones that were sequenced from both ends. Analysis of these full-length transcripts indicated that sizes of melon 5' and 3' UTRs were similar to those of tomato, but longer than many other dicot plants. Codon usages of melon full-length transcripts were largely similar to those of Arabidopsis coding sequences. CONCLUSION: The collection of melon ESTs generated from full-length enriched and standard cDNA libraries is expected to play significant roles in annotating the melon genome. The ESTs and associated analysis results will be useful resources for gene discovery, functional analysis, marker-assisted breeding of melon and closely related species, comparative genomic studies and for gaining insights into gene expression patterns.
Assuntos
Cucumis melo/genética , Etiquetas de Sequências Expressas , Biblioteca Gênica , Perfilação da Expressão Gênica , Marcadores Genéticos/genética , Genoma de Planta/genética , Genômica , Especificidade de Órgãos , Controle de Qualidade , Análise de Sequência de DNARESUMO
BACKGROUND: Real-time PCR is becoming a common tool for detecting and quantifying expression profiling of selected genes. Cytokines mRNA quantification is widely used in immunological research to dissect the early steps of immune responses or pathophysiological pathways. It is also growing to be of clinical relevancy to immuno-monitoring and evaluation of the disease status of patients. The techniques currently used for "absolute quantification" of cytokine mRNA are based on a DNA standard curve and do not take into account the critical impact of RT efficiency. RESULTS: To overcome this pitfall, we designed a strategy using external RNA as standard in the RT-PCR. Use of synthetic RNA standards, by comparison with the corresponding DNA standard, showed significant variations in the yield of retro-transcription depending the target amplified and the experiment. We then developed primers to be used under one single experimental condition for the specific amplification of human IL-1beta, IL-4, IL-10, IL-12p40, IL-13, IL-15, IL-18, IFN-gamma, MIF, TGF-beta1 and TNF-alpha mRNA. We showed that the beta-2 microglobulin (beta2-MG) gene was suitable for data normalisation since the level of beta2-MG transcripts in naive PBMC varied less than 5 times between individuals and was not affected by LPS or PHA stimulation. The technique, we named CyProQuant-PCR (Cytokine Profiling Quantitative PCR) was validated using a kinetic measurement of cytokine transcripts under in vitro stimulation of human PBMC by lipopolysaccharide (LPS) or Staphylococcus aureus strain Cowan (SAC). Results obtained show that CyProQuant-PCR is powerful enough to precociously detect slight cytokine induction. Finally, having demonstrated the reproducibility of the method, it was applied to malaria patients and asymptomatic controls for the quantification of TGF-beta1 transcripts and showed an increased capacity of cells from malaria patients to accumulate TGF-beta1 mRNA in response to LPS. CONCLUSION: The real-time RT-PCR technique based on a RNA standard curve, CyProQuant-PCR, outlined here, allows for a genuine absolute quantification and a simultaneous analysis of a large panel of human cytokine mRNA. It represents a potent and attractive tool for immunomonitoring, lending itself readily to automation and with a high throughput. This opens the possibility of an easy and reliable cytokine profiling for clinical applications.
Assuntos
Citocinas/genética , Perfilação da Expressão Gênica/métodos , RNA Mensageiro/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa/métodos , Adulto , Automação , Células Cultivadas/efeitos dos fármacos , Células Cultivadas/metabolismo , Criança , DNA/genética , Ensaio de Imunoadsorção Enzimática , Regulação da Expressão Gênica/efeitos dos fármacos , Humanos , Lipopolissacarídeos/farmacologia , Fatores Inibidores da Migração de Macrófagos/genética , Malária Falciparum/genética , Malária Falciparum/metabolismo , Padrões de Referência , Fator de Crescimento Transformador beta/biossíntese , Fator de Crescimento Transformador beta/genética , Fator de Crescimento Transformador beta1 , Fator de Necrose Tumoral alfa/genéticaRESUMO
Measurements of local Ca2+ signalling at different developmental stages and/or in specific cell types is important for understanding aspects of brain functioning. The use of light excitation in fluorescence imaging can cause phototoxicity, photobleaching and auto-fluorescence. In contrast, bioluminescence does not require the input of radiative energy and can therefore be measured over long periods, with very high temporal resolution. Aequorin is a genetically encoded Ca(2+)-sensitive bioluminescent protein, however, its low quantum yield prevents dynamic measurements of Ca2+ responses in single cells. To overcome this limitation, we recently reported the bi-functional Ca2+ reporter gene, GFP-aequorin (GA), which was developed specifically to improve the light output and stability of aequorin chimeras [V. Baubet, et al., (2000) PNAS, 97, 7260-7265]. In the current study, we have genetically targeted GA to different microdomains important in synaptic transmission, including to the mitochondrial matrix, endoplasmic reticulum, synaptic vesicles and to the postsynaptic density. We demonstrate that these reporters enable 'real-time' measurements of subcellular Ca2+ changes in single mammalian neurons using bioluminescence. The high signal-to-noise ratio of these reporters is also important in that it affords the visualization of Ca2+ dynamics in cell-cell communication in neuronal cultures and tissue slices. Further, we demonstrate the utility of this approach in ex-vivo preparations of mammalian retina, a paradigm in which external light input should be controlled. This represents a novel molecular imaging approach for non-invasive monitoring of local Ca2+ dynamics and cellular communication in tissue or whole animal studies.
Assuntos
Sinalização do Cálcio/fisiologia , Medições Luminescentes/métodos , Proteínas Luminescentes/análise , Proteínas Luminescentes/genética , Equorina/análise , Equorina/genética , Animais , Células COS , Células Cultivadas , Córtex Cerebral/química , Chlorocebus aethiops , Humanos , Técnicas In Vitro , CamundongosRESUMO
In Arabidopsis, the basic leucine zipper transcription factor ABI5 activates several late embryogenesis-abundant genes, including AtEm1 and AtEm6. However, the expression of many other seed maturation genes is independent of ABI5. We investigated the possibility that ABI5 homologs also participate in the regulation of gene expression during seed maturation. We identified 13 ABI5-related genes in the Arabidopsis genomic sequence. RNA gel blot analysis showed that seven of these genes are active during seed maturation and that they display distinct expression kinetics. We isolated and characterized two mutant alleles of one of these genes, AtbZIP12/EEL. Unlike abi5, the eel mutations did not inhibit the expression of any of the maturation marker genes that we monitored. On the contrary, the accumulation of the AtEm1 and AtEm6 mRNAs was enhanced in eel mutant seeds compared with wild-type seeds. Gel mobility shift assays, combined with analysis of the genetic interactions among the eel and abi5 mutations, indicated that ABI5 and EEL compete for the same binding sites within the AtEm1 promoter. This study illustrates how two homologous transcription factors can play antagonistic roles to fine-tune gene expression.
Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/genética , Regulação da Expressão Gênica de Plantas , Proteínas de Plantas/genética , Sementes/fisiologia , Fatores de Transcrição/metabolismo , Sequência de Aminoácidos , Arabidopsis/crescimento & desenvolvimento , Proteínas de Arabidopsis/antagonistas & inibidores , Proteínas de Arabidopsis/genética , Sequência de Bases , Fatores de Transcrição de Zíper de Leucina Básica , Primers do DNA , Regulação da Expressão Gênica no Desenvolvimento , Genes de Plantas , Zíper de Leucina , Dados de Sequência Molecular , Família Multigênica , Filogenia , Proteínas de Plantas/química , Reação em Cadeia da Polimerase , Regiões Promotoras Genéticas , Alinhamento de Sequência , Fatores de Transcrição/antagonistas & inibidores , Fatores de Transcrição/genéticaRESUMO
Using a transgenic line that overexpresses a fusion of the KNAT2 (KNOTTED-like Arabidopsis) homeodomain protein and the hormone-binding domain of the glucocorticoid receptor (GR), we have investigated the possible relations between KNAT2 and various hormones. Upon activation of the KNAT2-GR fusion, we observed a delayed senescence of the leaves and a higher rate of shoot initiation, two processes that are also induced by cytokinins and inhibited by ethylene. Furthermore, the activation of the KNAT2-GR fusion induced lobing of the leaves. This feature was partially suppressed by treatment with the ethylene precursor 1-aminocyclopropane-1-carboxylic acid, or by the constitutive ethylene response ctr1 mutation. Conversely, some phenotypic traits of the ctr1 mutant were suppressed by the activation of the KNAT2-GR fusion. These data suggest that KNAT2 acts synergistically with cytokinins and antagonistically with ethylene. In the shoot apical meristem, the KNAT2 gene is expressed in the L3 layer and the rib zone. 1-Aminocyclopropane-1-carboxylic acid treatment restricted the KNAT2 expression domain in the shoot apical meristem and reduced the number of cells in the L3. The latter effect was suppressed by the activation of the KNAT2-GR construct. Conversely, the KNAT2 gene expression domain was enlarged in the ethylene-resistant etr1-1 mutant or in response to cytokinin treatment. These data suggest that ethylene and cytokinins act antagonistically in the meristem via KNAT2 to regulate the meristem activity.