Selective inhibition of histone deacetylase 1 and 3 improves motor phenotype and alleviates transcriptional dysregulation in Huntington's disease mice

Huntingtons disease (HD) is an autosomal dominant neurodegenerative disease characterized by a late clinical onset of psychiatric, cognitive, and motor symptoms. Transcriptional dysregulation is an early and central disease mechanism which is accompanied by epigenetic alterations in HD. Previous studies demonstrated that targeting transcriptional changes by inhibition of histone deacetylases (HDACs), especially the class I HDACs, provides therapeutic effects. Yet, their exact mechanisms of action and the features of HD pathology, on which these inhibitors act remain to be elucidated. Here, using transcriptional profiling, we found that selective inhibition of HDAC1 and HDAC3 by RGFP109 repaired the expression of a number of genes, including the transcription factor genes Neurod2 and Nr4a2, and 43% of the gene sets that were dysregulated by mutant Huntingtin expression in the striatum and improved motor skill learning deficit in the R6/1 mouse model of HD. RGFP109-treated R6/1 mice showed improved coordination on the RotaRod over four consecutive trials, while vehicle-treated R6/1 animals displayed no improvement in coordination skills and fell 50 seconds earlier off the rod in the fourth trial. We also found, by volumetric MRI, a widespread brain atrophy in the R6/1 mice at the symptomatic disease stage, on which RGFP109 showed a modest effect. Collectively, our combined work presents new evidence for specific HDAC1 and HDAC3 inhibition as a therapeutic strategy for alleviating the phenotypic and molecular features of HD.