Abstract B155: Impact of transcription initation on translation regulation by the mTOR pathway

Abstract

The two major processes of eukaryotic gene expression, transcription and translation, are spatially and temporally separated and commonly perceived to be independently regulated. Unexpectedly, the analysis of nascent transcription start sites (TSSs) genome-wide, proposes that alternative TSS can target mRNAs of the same gene to distinct modes of translational regulation.Our preliminary data found the TCT core promoter motif to function as a transcriptionally suboptimal Initiator (Inr) motif. Despite the rapid turnover of most regulatory elements, the TCT motif is remarkably conserved among the promoters of orthologous bilaterians genes. However, the translation of mRNAs starting from TCT but not Inr promoters is preferentially regulated by the Mammalian target of rapamycin complex 1 (mTORC1), likely via the La-related protein 1 (Larp1) that binds mRNAs starting on pyrimidine but not purines. These findings reveal a functional dependency between transcription initiation and translation regulation, and highlight the importance of TSS selection in promoters. Inhibitors of mTORC1, and more recently Larp1, are rapidly moving into clinical cancer therapy trials but did not live up to the expectations in patients. Markers for patient stratification and predicting mTOR inhibitor efficacy are needed. As TSSs reflect the integrated signals of gene regulatory pathways and also appear to impact translational regulation, our future research will address how far alternative TSSs facilitate acquired resistance to mTOR inhibitors in tumors and 2) TSSs can serve as a predictive marker for mTOR inhibitors efficacy. Citation Format: Sascha H. Duttke, Max Chang, Christopher K. Glass, Andrea Berman, Christopher Benner. Impact of transcription initation on translation regulation by the mTOR pathway [abstract]. In: Proceedings of the Fourth CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; Sept 30-Oct 3, 2018; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2019;7(2 Suppl):Abstract nr B155.