Navegando por Autor "Carvalho, Omar"

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    Molecular characterization of SUMO E2 conjugation enzyme : differential expression profile in Schistosoma mansoni.
    (2011) Pereira, Roberta Verciano; Cabral, Fernanda Janku; Gomes, Matheus de Souza; Babá, Élio Hideo; Passos, Liana Konovaloff Jannotti; Carvalho, Omar; Rodrigues, Vanderlei; Afonso, Robson José de Cássia Franco; Borges, William de Castro; Cota, Renata Guerra de Sá
    SUMO-dependent post-translational modification is implicated in a variety of cellular functions including gene expression regulation, nuclear sub-localization, and signal transduction. Conjugation of SUMO to other proteins occurs in a similar process to ubiquitination, which involves three classes of enzymes: an E1 activating, an E2 conjugating, and an E3 target-specific ligase. Ubc9 is the unique SUMO E2 enzyme known to conjugate SUMO to target substrates. Here, we present the molecular characterization of this enzyme and demonstrate its expression profile during the S. mansoni life cycle. We have used bioinformatic approaches to identify the SUMO-conjugating enzyme, the SmUbc9-like protein, in the Schistosoma mansoni databases. Quantitative RT-PCR was employed to measure the transcript levels of SUMO E2 in cercariae, adult worms, and in vitro cultivated schistosomula. Furthermore, recombinant SmUbc9 was expressed using the Gateway system, and antibodies raised in rats were used to measure SmUbc9 protein levels in S. mansoni stages by Western blotting. Our data revealed upregulation of the SmUbc9 transcript in early schistosomula followed by a marked differential gene expression in the other analyzed stages. The protein levels were maintained fairly constant suggesting a post-transcriptional regulation of the SmUbc9 mRNA. Our results show for the first time that S. mansoni employs a functional SUMO E2 enzyme, for the conjugation of the SUMO proteins to its target substrates.
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    Preliminary analysis of miRNA pathway in Schistosoma mansoni.
    (2009) Gomes, Matheus de Souza; Cabral, Fernanda Janku; Passos, Liana Konovaloff Jannotti; Carvalho, Omar; Rodrigues, Vanderlei; Babá, Élio Hideo; Cota, Renata Guerra de Sá
    RNA silencing refers to a series of nuclear and cytoplasmatic processes involved in the post-transcriptional regulation of gene expression or post-transcriptional gene silencing (PTGS), either by sequence-specific mRNA degradation or by translational arrest. The best characterized small RNAs are microRNAs (miRNAs), which predominantly perform gene silencing through post-transcriptional mechanisms. In this work we used bioinformatic approaches to identify the parasitic trematode Schistosoma mansoni sequences that are similar to enzymes involved in the post-transcriptional gene silencing mediated by miRNA pathway.We used amino acid sequences of well-known proteins involved in the miRNA pathway against S. mansoni genome and transcriptome databases identifying a total of 13 putative proteins in the parasite. In addition, the transcript levels of SmDicer1 and SmAgo2/3/4 were identified by qRT-PCR using cercariae, adult worms, eggs and in vitro cultivated schistosomula. Our results showed that the SmDicer1 and SmAgo2/3/4 are differentially expressed during schistosomula development, suggesting that the miRNA pathway is regulated at the transcript level and therefore may control gene expression during the life cycle of S. mansoni.