HTT and Huntington disease: Treatment with DH1 reduced HSF1 translocation to mitochondria in HD striatal cells, YAC128 mice, human striatal organoids, and two lines of patient fibroblasts (Fig 6G–J), whereas the total protein levels of HSF1, Drp1, and HTT were not affected by the presence of DH1 (Fig EV4D and E).