One of the first responses to eukaryotic cellular stress is the formation of cytoplasmic granules like processing bodies (PBs) and stress granules (SGs). PBs are membrane-less structures that are dynamic in their assembly/disassembly and composition depending on the type of stress that they encounter. While glucose starvation is the main stress applied to study PB formation and dynamics, much less is known about PBs under other stresses, especially endoplasmic reticulum (ER) and mitochondrial/lysosomal stresses. We propose to study the formation, content and dynamics of PBs under ER and mitochondrial/lysosomal stresses, together with their turnover (autophagy/dissolution) during stress recovery. I plan to use pharmacological and acute genetic interventions to induce stresses. PBs will be purified according to the established protocol in the laboratory, which enables subsequent Liquid chromatography-mass spectrometry (LC-MS) analysis for proteins and RNA-sequencing for the RNA content. Probing stress response further, we will also perform total RNA-sequencing and Ribosome-profiling. The fate of specific sets of mRNAs will be determined by FISH-IF and RNA decay analysis, thereby identifying the signals effectuating PB localization and fate (storage or decay) during ER and mitochondrial/lysosomal stress. The study will be extended to check conservation of PB stress response in mammalian cells. The proposed research will provide a holistic view on the pathways that are up- or down-regulated during ER and mitochondrial/lysosomal stress, the identification of common pathways between the different stresses and PB -mRNA and protein- turnover. This project will be of high impact in the fields of cancer, cell, and neuro biology.