Supplemental Treatment for Huntington's Disease with miR-132 that Is Deficient in Huntington's Disease Brain

Huntington's disease (HD) is an intractable neurodegenerative disorder caused by mutant Huntingtin (HTT) proteins that adversely affect various biomolecules and genes. MicroRNAs (miRNAs), which are functional small non-coding RNAs, are also affected by mutant HTT proteins. Here, we show amelioration in motor function and lifespan of HD-model mice, R6/2 mice, by supplying miR-132 to HD brains using a recombinant adeno-associated virus (rAAV) miRNA expression system. miR-132 is an miRNA related to neuronal maturation and function, but the level of miR-132 in the brain of R6/2 mice was significantly lower than that of wild-type mice. Our miR-132 supplemental treatment, i.e., supplying miR-132 to the brain, produced symptomatic improvement or retarded disease progression in R6/2 mice; interestingly, it had little effect on disease-causing mutant HTT mRNA expression and its products. Therefore, the findings suggest that there may be a therapeutic way to treat HD without inhibiting and/or repairing disease-causing HTT genes and gene products. Although miR-132 supplement may not be a definitive treatment for HD, it may become a therapeutic method for relieving HD symptoms and delaying HD progression.