B08: Metabolic signaling as a safeguard of translational fidelity

Multiple signaling pathways including PI3K-Akt, Ras-MEK-ERK, (m)TOR and stress responses (Hülsmann…Weith et al. 2018; Weith et al. 2018) balance protein biosynthetic activity with cellular resources. Despite this intricate regulation, intrinsic and extrinsic demands on translational output can strain the capacities of the translational machinery and of quality control processes that protect against unfolding of nascent polypeptides. We have previously shown that altered kinetics of translation in unfavorable conditions such as insufficient loading of tRNAs can cause protein misfolding (Rauscher…Ignatova, 2021; Davyt…Ignatova, 2023). Furthermore, accumulation of translational stress during ageing can overwhelm ribosome-associated quality control (Stein et al. 2022). Conversely, interventions that reduce the activity of mTOR and ERK and consequently dampen translational activity were shown to improve cellular stress resistance and to increase longevity (Lu…Gorbunova, 2022). However, it remains elusive to what extent those beneficial effects are mediated via changes in translational fidelity or via changes in other cellular processes. In this project, we aim to delineate the importance of pathways that sense and signal the cellular metabolic state for the fidelity of translation and consequential effects on cellular homeostasis. We have previously established scoring of the combined outcome of PKA and TOR signaling in yeast based on marker protein levels (Weith et al. 2023). These pathways represent a central axis of the cellular network state that controls translational activity. In this project we will use similar methods to quantify the activity of translation-regulatory pathways in mammals. We will assess translation fidelity using reporter assays and ribosomal profiling in the presence of metabolic challenges such as nutrient deprivation, hypoxia and oxidative stress in a cellular model that allows titration of mTOR and ERK activity. These experiments will reveal how metabolic signaling alters the fidelity of translation and how those changes impact on the quality of the cellular transcriptome and proteome. We envision that pathway activity scoring and translational fidelity assessment in bulk proteomics data can be used to determine their relationship in health and disease.