BDNF and Huntington disease: In contrast, miR-124 overexpression would up-regulate BDNF and peroxisome proliferator-activated receptor gamma coactivator 1 (PGC1) expression and down-regulate SOX9 expression in the striatum of R6/2 mouse brain, which implies that miR-124 slows down the HD progression (Meza-Sosa et al., 2012).