Lack of RAN-mediated toxicity in Huntington’s disease knock-in mice

Identification of repeat-associated non-AUG (RAN) translation in trinucleotide (CAG) repeat diseases leads to an emerging concept that CAG repeat diseases are caused by non-polyglutamine products. Nonetheless, the exact contribution of RAN translation to the pathogenesis of CAG repeat diseases remains elusive. Via CRISPR/Cas9-mediated genome editing, we established new knock-in mouse models that harbor expanded CAG repeats in the mouse huntingtin gene, which express RAN translated products or polyglutamine products respectively. Here we report that RAN translation is not detected in the knock-in mouse models, and that only the expanded polyglutamine products can cause neuropathology and behavioral phenotypes. Therefore, polyglutamine products, rather than RAN translated products, play a major role in the pathogenesis of CAG repeat diseases. We performed RNA sequencing analysis using striatal tissues from 6-month old WT, E1 and KI-96 mice, each group includes at least four biological replicates.