Abstract
The mammalian target of rapamycin (mTOR) kinase is a well-known master regulator of growth-dependent gene expression in higher eukaryotes. Translation regulation is an important function of the mTORC1 pathway that controls the synthesis of many ribosomal proteins and translation factors. Housekeeping genes such as β-actin (ACTB) are widely used as negative control genes in studies of growth-dependent translation. Here we demonstrate that translation of both endogenous and reporter ACTB mRNA is inhibited in the presence of mTOR kinase inhibitor (Torin1) and under amino acid starvation. Notably, 5’UTR and promoter of ACTB are sufficient for the mTOR-dependent translational response, and the degree of mTOR-sensitivity of ACTB mRNA translation is cell type-dependent.
Highlights
The mammalian target of rapamycin (mTOR) signaling pathway is a well-known regulator of cell growth that responds to various growth stimuli, nutrients, energy, and stresses
Translation of Reporter mRNA with Promoter and 5’ UTR of ACTB is mTOR-Sensitive in HEK293T Cells
SLU7
Summary
The mTOR (mammalian target of rapamycin) signaling pathway is a well-known regulator of cell growth that responds to various growth stimuli, nutrients, energy, and stresses. As a master regulator of protein biosynthesis, the mTORC1 pathway is involved in cancer progression, obesity, diabetes, autism and aging [1,2,3]. Translation of mRNA of ribosomal and other translation-related proteins, such as elongation and initiation factors, is reduced under mTOR inhibition [5,6]. This class of mRNA targets share a common TOP motif (terminal oligopyrimidine tract) located at the extreme 5’end and described as an uninterrupted stretch of. With inhibited cell growth, the translation initiation factor eIF4E can discriminate 2–3 nucleotides at the mRNA 5’ end [9]. There are other mRNAs exhibiting growth-dependent translation inhibition, such as mRNAs with short 5’ UTRs carrying a specific TISU motif
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