FIGURE 8.

Prefoldin specifically affects cell viability by targeting polyQ-expanded HTT. A, Neuro-2a cells in 96-well plates were transfected with PFD2 siRNA, PFD5 siRNA, or nonspecific siRNA (N.S.) as a control. At 24 h after transfection, cells were treated with various amounts of staurosporine (A, panel a) and thapsigargin (A, panel b) for 24 h, and cell viability was examined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays. A negative control, shown as “nega,” indicates cells that were added with a transfection buffer and DMSO and then killed with 20% Triton X-100 before measuring their viability. A positive control, shown as “posi,” indicates cells that were added with a transfection buffer and DMSO. B, Neuro-2a cells were transfected with PFD2 siRNA, PFD5 siRNA, or nonspecific siRNA as a control for 24 h. Cells were then transfected with expression vectors for HTTQ78-GFP and HTTQ23-GFP. Twenty-four h after transfection, cells were treated with bafilomycin A1, an inhibitor of the late phase of autophagy, for 12 h. SDS-insoluble aggregates were then examined by a filter trap assay as described under “Experimental Procedures.”