| Resumo: | The mammalian target of rapamycin (mTOR) is a conserved serine/threonine kinase that integrates signals from the cellular nutrient- and energy-status, acting namely on the protein synthesis machinery. Deregulation of mTOR signaling is implicated in major diseases, such as cancer, mainly due to its role in regulating protein synthesis. Major advances are emerging regarding the regulators and effects of mTOR signaling pathway; however, regulation of mTOR gene expression is not well known. Here, we show that the 5’ untranslated region of the human mTOR transcript forms a highly folded RNA scaffold capable of binding directly to the 40S ribosomal subunit. We further demonstrate that this cis-acting RNA regulon is active both in normal and stress conditions, and that its activation status in response to translational adverse conditions parallels mTOR protein levels. Moreover, our data reveal that the cap-independent translation of mTOR is necessary for its ability to induce cell cycle progression into S-phase. These results suggest a novel regulatory mechanism of mTOR gene expression that integrates the protein profile rearrangement triggered by global translation inhibitory conditions.
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