Repeat RNA structure and protein interactions influence RAN translation and neurodegenerative phenotypes in models of FTD and ALS

Background The most common genetic cause of Frontotemporal dementia (FTD) and Amyotrophic Lateral Sclerosis (ALS) is an intronic GGGGCC hexanucleotide repeat expansion in C9orf72 (C9FTD/ALS). Transcribed RNAs sequester RNA-binding proteins (RBPs) into nuclear cytoplasmic foci, which inhibits their normal functions. also support translation toxic peptides through a process known as associated non-AUG (RAN) translation. Here we sought to understand how RNA secondary structure RBP engagements that occur during transcription, processing, trafficking influence RAN elicited toxicity, with goal identifying novel therapeutic targets. Method We developed cellular RNA-capture methodology coupled mass spectrometry identify RNA-interacting within specific compartments. In parallel, used chemical approaches probe structures inside cells assays determine whether and/or interacting RBPs efficiency. employed Drosophila neuronal models expansions evaluate potential disease modifiers. Result Our structural studies revealed form primarily hairpin structures, rather than G-quadruplex cells. Folding repat such hairpins supports whereas folding g-quadruplex strongly identified multiple enriching the fraction RNA-interactome, including hnRNPH1 SR (serine/arginine-rich domain) proteins, are components foci found C9FTD/ALS patient comparative analysis lowering protein expression or modifying its phosphorylation modified toxicity disorders. Currently investigating interactions dependent selectively modulate Conclusion present comprehensive approach roles critical underlying dementia-associated