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Publication
Translational control of the human erythropoietin via an upstream open reading frame in cardiac and muscle tissue
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Advisor(s)
Abstract(s)
Beyond its well-known hematopoietic action, erythropoietin (EPO) has diverse cellular effects in non-hematopoietic tissues. For example, in cases of tissue injury, such as cardiac ischemia or acute myocardial infarct, EPO expression increases locally, providing a cardioprotective effect. 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, including upstream open reading frames (uORFs).
The human EPO 5’ untranslated region (5’UTR) has one uORF with 14 codons that is conserved among different species, indicating its potential regulatory role. To test whether EPO expression is translationally regulated in response to ischemia in cardiac tissue, reporter constructs containing the normal or mutant EPO 5’UTR fused to the Firefly luciferase cistron were expressed in H9c2 (heart/myocardium myoblasts) and C2C12 (muscle myoblasts) cell lines. Luminometry assays revealed that the EPO uORF represses translation of the main ORF at about 60-70%, in both cell lines. Under chemical ischemia, EPO uORF-mediated translation repression is specifically released in muscle cells. In response to hypoxia, translational derepression occurs in both cell lines. Although the eIF2-alpha phosphorylation occurs in both conditions, thapsigargin treatment does not affect EPO translation. We are currently exploring additional mechanisms through which EPO cardioprotection effects are regulated at the translational level.
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Keywords
Genómica Funcional e Estrutural Expressão Génica Síntese Proteica