Correction of RBFOX1 deficit rescues Huntington's disease mis-splicing and pathology

Abstract

RNA mis-splicing correction therapies have been developed for neurological disorders like spinal muscular atrophy and neuronal ceroid lipofuscinosis. In Huntingtons disease (HD), pathogenic mis-splicing was initially observed in genes linked to neurodegeneration, such as HTT itself, MAPT, and TAF1. Later, genome-wide analyses identified a broader mis-splicing signature in HD brains, involving additional neurodegeneration-related genes. Correcting each mis-spliced gene individually would be unfeasible, highlighting the need to target upstream splicing factors altered in HD. Our previous motif-enrichment analyses of intronic sequences flanking the exons mis-spliced in HD identified RBFOX and U2AF2 as candidate splicing factors, both of which are reduced in HD brains. In this study, we tested their pathogenic relevance generating conditional transgenic mouse models that overexpress RBFOX1 or U2AF2 in forebrain neurons and combining them with HD mice. Our results show that moderate overexpression of RBFOX1, but not U2AF2, corrects multiple HD-associated mis-splicing events and alleviates HD mice neuropathology and motor symptoms. These findings demonstrate that RBFOX1 downregulation contributes to HD pathology and underscore the therapeutic potential of strategies aimed at increasing RBFOX1 levels.