Project description:In this study we are examining the paracrine effect induced by feline calicivirus (FCV) infection on stress granule (SG) accumulation. We provided an understanding of paracrine granules function and specificity through their affinity purification followed RNAseq to systematically analyse their RNA content.
Project description:We are here presenting a new paracrine induction of RNA granules by viruses. Infection by viruses imposes major stress on the host cell. In response to this stress, infected cells can induce several defence mechanisms, which include the activation of stress response pathways and the innate immune response. These often result in an inhibition of translation culminating in the assembly of cytoplasmic granules called stress granules (SGs). SGs assembly follows from liquid phase separation of aggregation-prone proteins such G3BP1 and TIA-1, leading to the sequestration of mRNAs. Because this threatens viral gene expression, viruses need to evade these stress response pathways to propagate. Using feline calicivirus (FCV), surrogate for norovirus, the main virus responsible for gastroenteritis outbreaks worldwide, we previously showed that FCV impairs SGs assembly by cleaving the scaffold protein G3BP1. Interestingly, we observed that uninfected bystander cells assembled G3BP1 granules, suggesting a paracrine response trigged by the infection. We now present evidence that virus-free supernatant generated from infected cells can induce the formation of RNA granules. We have characterised the dynamic of the granules assembly via confocal microscopy. Moreover, we provide an understanding of paracrine granules function and specificity through their affinity purification followed by proteomics and RNAseq analysis of their proteins and mRNAs content. This helps to define rules of assembly and novel functions for paracrine granules highlighting fundamental differences with canonical stress granules.
