Functional characterization of the sciarid BhC4-1 core promoter in transgenic Drosophila

<p>Abstract</p> <p>Background</p> <p>Core promoters are <it>cis</it>-regulatory modules to which bind the basal transcriptional machinery and which participate in the regulation of transcription initiation. Although core promoters have not been extensively investigated through functional assays in a chromosomal context, the available data suggested that the response of a given core promoter might vary depending on the promoter context. Previous studies suggest that a (-57/+40) fragment constitutes the core promoter of the <it>BhC4-1 </it>gene which is located in DNA puff C4 of the sciarid fly <it>Bradysia hygida</it>. Here we tested this (-57/+40) fragment in distinct regulatory contexts in order to verify if promoter context affects its core promoter activity.</p> <p>Results</p> <p>Consistent with the activity of a core promoter, we showed that in the absence of upstream regulatory sequences the (-57/+40) fragment drives low levels of reporter gene mRNA expression throughout development in transgenic <it>Drosophila</it>. By assaying the (-57/+40) fragment in two distinct regulatory contexts, either downstream of the previously characterized <it>Fbp1 </it>enhancer or downstream of the UAS element, we showed that the <it>BhC4-1 </it>core promoter drives regulated transcription in both the germline and in various tissues throughout development. Furthermore, the use of the <it>BhC4-1 </it>core promoter in a UAS construct significantly reduced salivary gland ectopic expression in third instar larvae, which was previously described to occur in the context of the GAL4/UAS system.</p> <p>Conclusions</p> <p>Our results from functional analysis in transgenic <it>Drosophila </it>show that the <it>BhC4-1 </it>core promoter drives gene expression regardless of the promoter context that was assayed. New insights into the functioning of the GAL4/UAS system in <it>Drosophila </it>were obtained, indicating that the presence of the SV40 sequence in the 3' UTR of a UAS construct does not preclude expression in the germline. Furthermore, our analysis indicated that ectopic salivary gland expression in the GAL4/UAS system does not depend only on sequences present in the GAL4 construct, but can also be affected by the core promoter sequences in the UAS construct. In this context, we propose that the sciarid <it>BhC4-1 </it>core promoter constitutes a valuable core promoter which can be employed in functional assays in insects.</p

Genes e epilepsia I: epilepsia e alterações genéticas Genes and epilepsy I: epilepsy and genetic alterations

INTRODUÇÃO: Epilepsia é uma desordem neurológica caracterizada por crises espontâneas e recorrentes, que afeta de 2% a 3 % da população mundial. As crises epilépticas refletem atividade elétrica anormal e paroxística, preferencialmente em uma ou várias áreas do córtex cerebral, que podem ser causadas por inúmeras patologias estruturais ou neuroquímicas. Dentre os importantes estudos das últimas décadas no campo da epileptologia, destaca-se a identificação de genes associados a certos tipos de epilepsia. OBJETIVO: Nesta revisão, descrevemos as principais alterações genéticas associadas ao processo epileptogênico, discutindo as mais recentes descobertas e suas contribuições para a compreensão das bases genéticas das epilepsias idiopáticas monogênicas (EIM) e das epilepsias geneticamente complexas. RESULTADOS E CONCLUSÃO: Estudos de ligação e associação mostram que alterações em genes que codificam canais iônicos são as principais causas genéticas das epilepsias idiopáticas monogênicas e de predisposição nas epilepsias geneticamente complexas. Além disso, as síndromes nas quais a epilepsia é um aspecto importante do quadro clínico podem ser provocadas por genes envolvidos em diferentes vias celulares, tais como: migração neuronal, metabolismo de glicogênio e cadeia respiratória. Portanto, acredita-se que diferentes categorias de genes possam atuar na determinação do traço epiléptico. A identificação de tais famílias de genes não apenas nos ajudará a entender as vias moleculares associadas à hiperexcitabilidade neuronal e ao processo epileptogênico, mas também poderá conduzir ao desenvolvimento de novas e mais precisas estratégias de tratamento da epilepsia.<br>INTRODUCTION: Epilepsy is a neurological disorder characterized by spontaneous and recurrent seizures with an estimated prevalence of 2-3 % in the world population. Epileptic seizures are the result of paroxystic and hypersynchronous electrical activity, preferentially in cortical areas, caused by panoply of structural and neurochemical dysfunctions. Recent advances in the field have focused on the molecular mechanisms involved in the epileptogenic process. OBJECTIVES: In the present review, we describe the main genetic alterations associated to the process of epileptogenesis and discuss the new findings that are shedding light on the molecular substrates of monogenic idiopathic epilepsies (MIE) and on genetically complex epilepsies (GCE). RESULTS AND CONCLUSION: Linkage and association studies have shown that mutations in ion channel genes are the main causes of MIE and of predisposition for GCE. Moreover, mutations in genes involved in neuronal migration, glycogen metabolism and respiratory chain are associated to other syndromes involving seizures. Therefore, different gene classes contribute to the epileptic trait. The identification of epilepsy-related gene families can help us understand the molecular mechanisms of neuronal hyperexcitability and recognize markers of early diagnosis as well as new treatments for these epilepsies