Targeting Staufen 1 with antisense oligonucleotides for treating ALS and SCA2

ABSTRACTStaufen1 (STAU1) is a multifunctional RNA binding protein that controls mRNA degradation and subcellular localization. STAU1 interacts with the ATXN2 protein, that is polyglutamine expanded in spinocerebellar ataxia type 2 (SCA2). We previously showed that STAU1 is elevated and aggregated in cells from SCA2 patients, cells from amyotrophic lateral sclerosis (ALS) patients, and in SCA2 and ALS mouse models. We also found that reduction of STAU1 abundancein vivoby genetic interaction improved motor behavior in an SCA2 mouse model, normalized the levels of several SCA2-related proteins, and reduced aggregation of polyglutamine-expanded ATXN2. Here we developed antisense oligonucleotides (ASOs) lowering STAU1 expression toward developing a therapeutic that may be effective for treating SCA2 and ALS. We performed a screen of 118 20mer phosphorothioate 2’-O-methoxyethyl (MOE) ASO gapmers targeting across theSTAU1mRNA coding region for lowering STAU1 expression in HEK-293 cells. ASO hits lowering STAU1 by >45 % were rescreened in SCA2 patient fibroblasts, and 10 of these were tested for lowering STAU1 abundancein vivoin a new BAC-STAU1 mouse model. This identified efficacious ASOs targeting humanSTAU1 in vivothat normalized autophagy marker proteins, including ASO-45 that also targets mouseStau1. When delivered by intracerebroventricular (ICV) injection, ASO-45 normalized autophagy markers and abnormal mRNA abundances in cerebella of ATXN2-Q127 SCA2 mice, as well as ChAT, NeuN and cleaved caspase-3 in spinal cord ofThy1-TDP-43 transgenic mice. TargetingSTAU1may be an effective strategy for treating ALS and SCA2 as well as other disorders characterized by its overabundance.