In vivo Drosophila model
The nervous system driver line elav-GAL4 and the UAS-fl-HTT-Q128 (expressing human full-length HTT with 128Q when crossed to the GAL4 line) lines were obtained from the Bloomington Drosophila Stock Center at University of Indiana (http://flystocks.bio.indiana.edu/). The UAS-HTT-exon1-Q72 line was generated by injecting the pUAST-HTT-exon1-Q72 vector into w1118 Drosophila embryos, and the UAS-HTT-exon1-Q72 was integrated to chromosome 2 (33). This line expresses N-terminal human HTT-exon1 fragment with 72Q when crossed with the GAL4 line, and the expression was validated by both HTRF (see the “HTRF assay for Htt measurements” section below) and Western-blot analysis.
For Drosophila behavioral experiments, we placed 15 age-matched virgin females flies in an empty vial and tapped them down. The percentage of flies that climbed past a 9-cm-high line after 10 seconds was recorded and analyzed by two-way ANOVA tests. Blinding was used for performing the experiments. For survival analysis, we recorded the survival of 15 age-matched virgin female flies during the feeding with gossypol acetate. The survival time of flies was recorded and analyzed by two-way ANOVA tests. Blinding was used for performing the experiments.