(A–D) Horizontal cryosections of 1-d flies indicate two modes of activity of suppressors on disease protein accumulations: reduction or no effect.
(A) Control flies showing NI of full-length SCA3Q84 protein. Genotype w; gmr-GAL4 UAS-SCA3Q84 /+.
(B) ImpEP1433 has no effect on NI. Genotype ImpEP1433; gmr-GAL4 UAS-SCA3Q84/+.
(C) Hsp68E407 and (D) CG5009B227.2 decrease NI. Genotypes (C) w; gmr-GAL4 UAS-SCA3Q84/+; E407/+ and (D) w; gmr-gal4 UAS-SCA3Q84 /B227.2.
(E) Western blot shows that all suppressors increase the solubility of the disease protein. Normally, no monomer is seen in the line expressing strong SCA3trQ78 (lane 1). Upon co-expression of suppressors, monomer level of disease protein increases, indicative of increased solubility. Genotype w; gmr-GAL4 UAS-SCA3Q84 in trans to indicated suppressors.
(F and H) Horizontal retinal sections of 7-d flies.
(F) NI in flies expressing SCA3trQ78 are strongly reduced by Dpld.
(H) Endogenous Hsp70 stress response is also strongly reduced by Dpld. Genotypes (F–H left panel) w; UAS-SCA3trQ78/+; rh1-GAL4 /+ and (F–H right panel) w; UAS-SCA3trQ78/+; rh1-GAL4 / dpld J990-P2.
(I) Western blots of 7-d flies showing that reduced stress response, as determined by levels of endogenous Hsp70, correlates with increased solubility of disease protein. Dpld increases disease protein monomer level and reduces stress-induced Hsp70. Genotype w; UAS-SCA3trQ78; rh1-GAL4 in trans to +, dpldJ990-P2, dpldJM265, dpldJM265ex, and hHsp70.