Signal transduction-related responses to phytohormones and environmental challenges in sugarcane

Background: Sugarcane is an increasingly economically and environmentally important C4 grass, used for the production of sugar and bioethanol, a low-carbon emission fuel. Sugarcane originated from crosses of Saccharum species and is noted for its unique capacity to accumulate high amounts of sucrose in its stems. Environmental stresses limit enormously sugarcane productivity worldwide. To investigate transcriptome changes in response to environmental inputs that alter yield we used cDNA microarrays to profile expression of 1,545 genes in plants submitted to drought, phosphate starvation, herbivory and N-2-fixing endophytic bacteria. We also investigated the response to phytohormones (abscisic acid and methyl jasmonate). The arrayed elements correspond mostly to genes involved in signal transduction, hormone biosynthesis, transcription factors, novel genes and genes corresponding to unknown proteins.Results: Adopting an outliers searching method 179 genes with strikingly different expression levels were identified as differentially expressed in at least one of the treatments analysed. Self Organizing Maps were used to cluster the expression profiles of 695 genes that showed a highly correlated expression pattern among replicates. The expression data for 22 genes was evaluated for 36 experimental data points by quantitative RT-PCR indicating a validation rate of 80.5% using three biological experimental replicates. The SUCAST Database was created that provides public access to the data described in this work, linked to tissue expression profiling and the SUCAST gene category and sequence analysis. The SUCAST database also includes a categorization of the sugarcane kinome based on a phylogenetic grouping that included 182 undefined kinases.Conclusion: An extensive study on the sugarcane transcriptome was performed. Sugarcane genes responsive to phytohormones and to challenges sugarcane commonly deals with in the field were identified. Additionally, the protein kinases were annotated based on a phylogenetic approach. The experimental design and statistical analysis applied proved robust to unravel genes associated with a diverse array of conditions attributing novel functions to previously unknown or undefined genes. The data consolidated in the SUCAST database resource can guide further studies and be useful for the development of improved sugarcane varieties.

Transcription profiling of signal transduction-related genes in sugarcane tissues

A collection of 237,954 sugarcane ESTs was examined in search of signal transduction genes. Over 3,500 components involved in several aspects of signal transduction, transcription, development, cell cycle, stress responses and pathogen interaction were compiled into the Sugarcane Signal Transduction (SUCAST) Catalogue. Sequence comparisons and protein domain analysis revealed 477 receptors, 510 protein kinases, 107 protein phosphatases, 75 small GTPases, 17 G-proteins, 114 calcium and inositol metabolism proteins, and over 600 transcription factors. The elements were distributed into 29 main categories subdivided into 409 sub-categories. Genes with no matches in the public databases and of unknown function were also catalogued. A cDNA microarray was constructed to profile individual variation of plants cultivated in the field and transcript abundance in six plant organs (flowers, roots, leaves, lateral buds, and 1(st) and 4(th) internodes). From 1280 distinct elements analyzed, 217 (17%) presented differential expression in two biological samples of at least one of the tissues tested. A total of 153 genes (12%) presented highly similar expression levels in all tissues. A virtual profile matrix was constructed and the expression profiles were validated by real-time PCR. The expression data presented can aid in assigning function for the sugarcane genes and be useful for promoter characterization of this and other economically important grasses.

Effects of fluoride intake on insulin sensitivity and insulin signal transduction

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Endurance training improves responsiveness to insulin and modulates insulin signal transduction through the phosphatidylinositol 3-kinase/Akt-1 pathway

Background: Endurance training increases insulin-stimulated muscle glucose transport and leads to improved metabolic control in diabetic patients.Objective: To analyze the effects of endurance training on the early steps of insulin action in muscle of rats. Design: Male rats submitted to daily swimming for 6 weeks were compared with sedentary controls. At the end of the training period, anesthetized animals received an intravenous (i.v.) injection of insulin and had a fragment of their gastrocnemius muscle excised for the experiments.Methods: Associations between insulin receptor, insulin receptor substrates (IRS)-1 and -2 and phosphatidylinositol 3-kinase (PI3-kinase) were analyzed by immunoprecipitation and immunoblotting. Akt-1 serine phosphorylation and specific protein quantification were detected by immunoblotting of total extracts, and IRS-1/IRS-2-associated PI3-kinase activity were determined by thin-layer chromatography.Results: Insulin-induced phosphorylation of IRS-1 and IRS-2 increased respectively by 1.8-fold (P < 0.05) and 1.5-fold (P < 0.05), whereas their association with PI3-kinase increased by 2.3-fold (P < 0.05) and 1.9-fold (P < 0.05) in trained rats as compared with sedentary controls, respectively. The activity of PI3-kinase associated with IRS-1 and IRS-2 increased by 1.8-fold (P < 0.05) and 1.7-fold (P < 0.05) respectively, in trained rats as compared with their untrained counterparts. Serine phosphorylation of Akt-1/PKB increased 1.7-fold (P < 0.05) in trained rats in response to insulin. These findings were accompanied by increased responsiveness to insulin as demonstrated by a reduced area under the curve for insulin during an i.v. glucose tolerance test, by increased glucose disappearance rate during an insulin tolerance test, and by increased expression of glucose transporter-4.Conclusions: the increased responsiveness to insulin induced by chronic exercise in rat skeletal muscle may result, at least in part, from the modulation of the insulin signaling pathway at different molecular levels.

Chemotactic signal transduction and phosphate metabolism as adaptive strategies during citrus canker induction by Xanthomonas citri

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Crystal structure of Bn IV in complex with myristic acid: A Lys49 myotoxic phospholipase A(2) from Bothrops neuwiedi venom

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Sugarcane genes differentially expressed during water deficit

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Análise do perfil de expressão dos genes da cana-de-açúcar envolvidos na interação com Leifsonia xyli subsp: xyli

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Induction of apoptosis in A549 pulmonary cells by two Paracoccidioides brasiliensis samples

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Gene Expression Profiles Stratified according to Type 1 Diabetes Mellitus Susceptibility Regions

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Epithelial cells treated with genistein inhibit adhesion and endocytosis of Paracoccidioides brasiliensis

Paracoccidioidomycosis is caused by Paracoccidioides brasiliensis, which although not formally considered an intracellular pathogen, can be internalized by epithelial cells in vitro and in vivo. The mechanisms used by P. brasiliensis to adhere to and invade non-professional phagocytes have not been identified. The signal-transduction networks, involving protein tyrosine kinase (PTK) and protein phosphatase activities, can modulate crucial events during fungal infections. In this study, the involvement of PTK has been investigated in P. brasiliensis adherence and invasion in mammalian epithelial cells. A significant inhibition of the fungal invasion occurred after the pre-treatment of the epithelial cells with genistein, a specific tyrosine kinase inhibitor, indicating that the tyrosine kinase pathway is involved in P. brasiliensis internalization. In contrast, when the fungus was treated, a slight (not significant) inhibition of PTK was observed, suggesting that PTK might not be the fungus' transduction signal pathway during the invasion process of epithelial cells. An intense PTK immunofluorescence labeling was observed in the periphery of the P. brasiliensis infected cells, little PTK labeling was found in both uninfected cells and yeast cells, at later infection times (8 and 24 h). Moreover, when the epithelial cells were treated with genistein and infected with P. brasiliensis, no labeling was observed, suggesting the importance of the PTK in the infectious process. These results suggest that PTK pathway participates in the transduction signal during the initial events of the adhesion and invasion processes of P. brasiliensis to mammalian epithelial cells.

Context-specific modulation of cocaine-induced locomotor sensitization and ERK and CREB phosphorylation in the rat nucleus accumbens

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Analysis and functional annotation of an expressed sequence tag collection for tropical crop sugarcane

To contribute to our understanding of the genome complexity of sugarcane, we undertook a large-scale expressed sequence tag (EST),program. More than 260,000 cDNA clones were partially sequenced from 26 standard cDNA libraries generated from different sugarcane tissues. After the processing of the sequences, 237,954 high-quality ESTs were identified. These ESTs were assembled into 43,141 putative transcripts. of the assembled sequences, 35.6% presented no matches with existing sequences in public databases. A global analysis of the whole SUCEST data set indicated that 14,409 assembled sequences (33% of the total) contained at least one cDNA clone with a full-length insert. Annotation of the 43,141 assembled sequences associated almost 50% of the putative identified sugarcane genes with protein metabolism, cellular communication/signal transduction, bioenergetics, and stress responses. Inspection of the translated assembled sequences for conserved protein domains revealed 40,821 amino acid sequences with 1415 Pfam domains. Reassembling the consensus sequences of the 43,141 transcripts revealed a 22% redundancy in the first assembling. This indicated that possibly 33,620 unique genes had been identified and indicated that >90% of the sugarcane expressed genes were tagged.

Periodontal Disease Decreases Insulin Sensitivity and Insulin Signaling

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Lipopolysaccharide-induced Stem Cell Factor Messenger RNA Expression and Production in Odontoblast-like Cells

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)