Browsing by Issue Date, starting with "2014-11-19"
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- Translational control of the human erythropoietin via an upstream open reading frame in cardiac tissuePublication . Onofre, Claudia; Barbosa, Cristina; Romão, LuísaErythropoietin (EPO) is the main hormone that regulates erythropoiesis. Beyond its well-known hematopoietic action, EPO has diverse cellular effects in non-hematopoietic tissues, including cardioprotection. Indeed, in cases of tissue injury the EPO expression increases locally providing a cardioprotective effect supported by numerous experimental data in animal models of ischemia and acute myocardial infarct. Cellular stress activates an integrated stress response, which includes rapid changes in global and gene-specific translation. Translational regulation of specific transcripts mostly occurs at translation initiation and is mediated via different cis-acting elements present in the mRNA 5’ untranslated region (5’UTR); which includes the upstream open reading frames (uORFs). These uORFs modulate translation of the main ORF by decreasing the number and/or efficiency of scanning ribosomes to reinitiate at the start codon of the main ORF. However, in response to abnormal stimuli, they mediate translational derepression of stress-responsive proteins. The 5’ leader sequence of the human EPO mRNA has one uORF with 14 codons that is conserved among different species, indicating its potential regulatory role. In the present work, we aimed to test whether EPO expression is translationally regulated in response to ischemia in cardiac tissue. Reporter constructs containing the normal or mutant EPO 5’ leader sequence fused to the Firefly luciferase cistron were tested in H9C2 (rat heart/myocardium myoblasts) and C2C12 (mouse muscle myoblasts) cell lines. Luciferase activity was measured by luminometry assays and normalized to the corresponding mRNA levels quantified by real-time RT-PCR. Results have revealed that the EPO uORF represses translation of the main ORF at about 60-70%, in both cell lines. The results also show the synthesis of EPO protein mainly occurs by reinitiation after uORF translation demonstrating that this uORF suffers low leaky scanning. In addition, our results show that specifically in C2C12 cells, the EPO 3’-enhancer induces a 4-fold increase in EPO expression, while in H9C2 cells the uORF-mediated translational repression is not affected by the presence of the EPO 3’-enhancer. Nevertheless, in C2C12 cells under chemical ischemia, EPO uORF-mediated translation repression seems to be released. These findings show that cardioprotection effects of EPO might be regulated at the translational level.
- Cytogenetic Laboratory microarray experience: case reports presentationPublication . Marques, Bárbara
- Protein Interaction Networks Reveal Novel Autism Risk Genes within GWAS Statistical NoisePublication . Correia, C.; Oliveira, G.; Vicente, A.M.Genome-wide association studies (GWAS) for Autism Spectrum Disorder (ASD) thus far met limited success in the identification of common risk variants, consistent with the notion that variants with small individual effects cannot be detected individually in single SNP analysis. To further capture disease risk gene information from ASD association studies, we applied a network-based strategy to the Autism Genome Project (AGP) and the Autism Genetics Resource Exchange GWAS datasets, combining family-based association data with Human Protein-Protein interaction (PPI) data. Our analysis showed that autism-associated proteins at higher than conventional levels of significance (P<0.1) directly interact more than random expectation and are involved in a limited number of interconnected biological processes, indicating that they are functionally related. The functionally coherent networks generated by this approach contain ASD-relevant disease biology, as demonstrated by an improved positive predictive value and sensitivity in retrieving known ASD candidate genes relative to the top associated genes from either GWAS, as well as a higher gene overlap between the two ASD datasets. Analysis of the intersection between the networks obtained from the two ASD GWAS and six unrelated disease datasets identified fourteen genes exclusively present in the ASD networks. These are mostly novel genes involved in abnormal nervous system phenotypes in animal models, and in fundamental biological processes previously implicated in ASD, such as axon guidance, cell adhesion or cytoskeleton organization. Overall, our results highlighted novel susceptibility genes previously hidden within GWAS statistical "noise" that warrant further analysis for causal variants.
- Avaliação do Estado Nutricional de crianças dos 0-3 anos da USF Cidadela, CascaisPublication . Leal, S.; Costa, C.; Arruda, N.; Vasco, Elsa; Alvito, Paula