UNDERPIN · Untranslated regions of RNAs and protein networks in pathological phase separation: UNDERPIN

Aggregation of RNA binding proteins (RBPs) is a pathological hallmark of neurodegenerative pathologies such as Amyotrophic Lateral Sclerosis. The mechanism leading to RBP aggregation relies on the ability of these proteins to transition into membrane-less compartments such as the stress granules (SG) whose formation is normally regulated in physiological conditions. Yet, as RBPs are intrinsically prone to coalesce in large assemblies, their accumulation, when unregulated, can lead to cell toxicity. While the effects of amino acid mutations on RBP aggregation have been extensively investigated, a large amount of evidence indicates that nucleotide variants in untranslated regions (UTRs) can strongly impact RBP expression by altering the interactions with specific regulatory proteins. UTRs provide a platform where multiple RBPs bind to orchestrate post-transcriptional regulation. I envision that UTRs, by directing contacting specific protein networks are crucial in aggregate formation and that alteration of their interactomesdue to disease-linked mutationscould impact the propensity to form SG and other assemblies. The main objective of UNDERPIN is to reveal interactions in regulatory regions of RBPs and to understand their effects on phase separation in physiology and pathology. Firstly, I plan to investigate the effects of disease-linked mutations on UTRs of RNAs encoding RBPs by large-scale predictions of UTR-RBP interactors. Secondly, interactions between RBP and selected UTRs, with and without disease-linked mutations, will be revealed in human cells by RNA-protein interaction detection experimental method RaPID. Finally, the biological implications of UTR-mediated recruitment of RBPs will be deciphered providing molecular details on how UTRs and RBPs promote the formation of aggregates. Successful completion of this project will not only lead to new insights into RBP biology, but will also pave the way to understand early events of neurodegeneration.