H1152 promotes the degradation of polyglutamine-expanded ataxin-3 or ataxin-7 independently of its ROCK-inhibiting effect and ameliorates mutant ataxin-3-induced neurodegeneration in the SCA3 transgenic mouse

► H1152 decreased protein level of mutant ataxin-3-Q79 expressed in 293 cells. ► H1152 promoted the degradation of ataxin-3-Q79 by augmenting proteasome activity. ► H1152 enhanced ataxin-3-Q79 degradation independently of its ROCK-inhibiting effect. ► H1152 reduced ataxin-3-Q79 level in SCA3 affected CNS areas of SCA3 transgenic mice. ► H1152 ameliorated pontine neuronal death and ataxic symptom of SCA3 transgenic mice.