CAG repeat expansion in the Huntington ’s disease gene shapes linear and circular RNAs biogenesis

by Dilara Ayyildiz, Guendalina Bergonzoni, Alan Monziani, Takshashila Tripathi, Jessica D öring, Emanuela Kerschbamer, Francesca Di Leva, Elia Pennati, Luisa Donini, Marina Kovalenko, Jacopo Zasso, Luciano Conti, Vanessa C. Wheeler, Christoph Dieterich, Silvano Piazza, Erik Dassi, Marta Biagioli Alternative splicing (AS) appears to be altered in Huntington ’s disease (HD), but its significance for early, pre-symptomatic disease stages has not been inspected. Here, taking advantage ofHtt CAG knock-in mousein vitro andin vivo models, we demonstrate a correlation betweenHtt CAG repeat length and increased aberrant linear AS, specifically affecting neural progenitors and,in vivo, the striatum prior to overt behavioral phenotypes stages. Remarkably, a significant proportion (36%) of the aberrantly spliced isoforms are not-functional and meant to non-sense mediated decay (NMD). The expandedHtt CAG repeats further reflect on a previously neglected, global impairment of back-splicing, leading to decreased circular RNAs production in neural progenitors. Integrative transcriptomic analyses unveil a network of transcriptionally altered micro-RNAs and RNA-binding proteins (CELF, hnRNPS, PTBP, SRSF, UPF1, YTHD2) which might influence the AS machinery, primarily in neural cells. We suggest that this unbalanced expression of linear and circular RNAs might alter neural fitness, contributing to HD pathogenesis.
Source: PLoS Genetics - Category: Genetics & Stem Cells Authors: Source Type: research