Fig. 5.
Expression of a clinically protective Lrrk mutant reduces α-synuclein neurotoxicity and decreases Lrrk oligomerization. a, Expression of Lrrk-Q1003H, analogous to the protective human LRRK2-R1398H variant, rescues the locomotor dysfunction produced by expression of α-synuclein. b-c, Lrrk-Q1003H suppresses the loss of medullary hematoxylin-stained neurons (b), as quantified in (c), and tyrosine hydroxylase immunostained neurons (d arrows), as quantified in (e) when compared to flies expressing α-synuclein alone. Scale bars represent 10 µm in (b) and 5 µm in (d). n=6 per genotype. f, Western blotting reveals no change in transgenic human α-synuclein levels with expression of Lrrk-Q1003H. The blot is reprobed for GAPDH to illustrate equivalent protein loading. g, Increased levels of F-actin as assayed by phalloidin staining on whole mount brains (top) and quantified (bottom) are reversed by expressing Lrrk-Q1003H. Scale bar in (g) represents 75 µm. h, Similarly, the formation of actin rods (top arrows) and quantified (bottom) is also rescued by expression of Lrrk-Q1003H when compared to flies expressing α-synuclein alone. Scale bar in (h) represents 15 µm. i,j, The α-synuclein induced decline in OCR is partially rescued by expression of Lrrk-Q1003H when compared to flies expressing α-synuclein alone. k, Native gel electrophoresis followed by western blotting (k) and quantitative analysis (l) demonstrates a significant reduction in the ratio of Lrrk multimer to monomer in flies expressing Lrrk-Q1003H compared to Lrrk-HA control flies. Data are represented as mean ± SD. n=3-6 per genotype. *p<0.05, ** p<0.01, ***p<0.005, ns, not significant, ANOVA with Bonferroni post-test analysis. Control is nSyb-GAL4, nSybQF2/+ in (a-j). Control is nSyb-GAL4/+ in (k). Lrrk-HA is LrrkHA, nSyb-GAL4/+ in (k,l). Flies are 10 days old in (a-e, g-l) and 1 day old in (f)