The potential function of alternative translation initiation of Argonaute 1 in cancer

Vieira da Silva, Verónica; Lacerda, Rafaela; Romão, Luísa

http://hdl.handle.net/10400.18/10854

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Autores

Vieira da Silva, Verónica

Lacerda, Rafaela

Romão, Luísa

Resumo(s)

Translation is one of the most regulated and energy-consuming cellular processes crucial for proper cell function. Translation is initiated by the canonical cap-dependent mechanism. However, under stress conditions, the initiation of canonical translation is inhibited, which allows the translation of specific proteins via alternative mechanisms. This project aims to understand the biological relevance of alternative protein synthesis mechanisms in Argonaute 1 (AGO1) expression. The AGO1 protein is involved in microRNA regulation, gene expression modulation and inhibition. AGO1 is also involved in the regulation of gene expression by RNA interference (RNAi), and its deregulation can lead to the activation of oncogenes or the suppression of tumor suppressor genes, contributing to the development and progression of cancer. Our work has shown that AGO1 mRNA can be translated through a cap-independent initiation mechanism. An upstream open reading frame (uORF) has also been identified in its 5’ untranslated region (5’UTR), which may play a role in the initiation of AGO1 translation. The results showed that the 5’UTR of human AGO1 supports a cap-independent mechanism of translation initiation, which is maintained under stress conditions. However, our analyses did not provide conclusive evidence for a regulatory role of the uORF in this initiation process. To this end, the 5’UTR of human AGO1 was cloned into a bicistronic vector containing Renilla (RLuc) and Firefly luciferase (FLuc), with FLuc positioned downstream of the 5’UTR. Luminometry assays will be used to evaluate the relative FLuc/RLuc translation efficiency under the control of the AGO1 5’UTR. The same approach will be used with monocistronistic reporter vectors, contaning only FLuc. This project aims to understand how these alternative mechanisms of mRNA translation initiation can influence AGO1 expression and help explain their potential roles in certain pathologies and cancer progression, such as colorectal cancer.