Figure 4. Effects of protein quality control factors in Drosophila.

(a) Scheme of the climbing (negative geotaxis) assay in adult Drosophila expressing human SOD1^A4V in motor neurons (left). Quantification of the climbing ability of Drosophila expressing human SOD1^A4V in motor neurons together with gene-specific or control RNAi is shown (right; n=4 independent groups; ** P(l3mbt)=0.007, * P(Pr-set7)=0.025, ** P(dp53)=0.002). (b) Protein levels of mutant SOD1^A4V in adult Drosophila motor neurons, upon treatment with gene specific or control RNAi (n=3 independent groups; ** P(l3mbt)=0.002, * P(Pr-set7)=0.036, * P(dp53)=0.036). (c) The reduction of l(3)mbt by RNAi strongly suppressed the eye degeneration phenotypes in both poly-GR or poly-PR strains when compared with the control Luc RNAi strain. Scale Bar: 100 μm. (d) Quantification of pigment content in adult eyes confirms the protection against degeneration by loss of l(3)mbt in both poly-GR or poly-PR strains. The measurements represent three independent groups with each containing fly heads from four males and four females (n=3; ** P(l3mbt)=0.0016, * P(Su(Var)3–3)=0.046, * P(Pr-set7)=0.015 with poly-GR. ** P(l3mbt)=0.0025, * P(Su(Var)3–3)=0.027, **** P(Pr-set7)<0.0001 with poly-PR). (e) The degenerative rough-eye phenotype of adult flies is alleviated by the reduction of protein demethylase Su(Var)3–3, but aggravated by the reduction of Drosophila homolog of SETD8, Pr-set7, or dp53. Scale Bar: 100 μm. (f) Quantification of the pigment content from degenerating eyes confirms the observation of the rough-eye phenotypes in the suppressor and enhancer strains. The measurements represent three independent groups with each containing fly heads from four males and four females (n=3; *** P(l3mbt)=0.0008, * P(l3mbt+dp53)=0.036 with poly-GR. ** P(l3mbt)=0.002, ** P(l3mbt+dp53)=0.0011 with poly-PR). Error bars represent ± SEM.