Fig. 3

Modifying dZIP1 levels markedly influences the brain Aβ42 fibril deposition and lifespan in a Drosophila AD model. a-b Thioflavin-S (TS) staining was used to detect Aβ42 fibril deposits (bright green dots) in fly brains. Few deposits were found in the control brains (Elav-Gal4, top left) at 25 days after eclosion (dae). TS-positive deposits were found after Aβ42 expression in fly brains (Elav-Gal4 > UAS-Aβ42) at both a 25 and b 30 dae. c The quantitative content of Aβ42 deposits was summarized and expressed after normalization to 25-day old Aβ42 flies. The increase in Aβ42 deposits was age-dependent. Overexpression of dZIP1 in Aβ42-expressing brains (Elav-Gal4 > UAS-Aβ42/UAS-dZIP1) significantly increased fibril deposits at 25 dae, which was higher than 30 dae Aβ42 flies. However, inhibition of dZIP1 (Elav-Gal4 > UAS-Aβ42/UAS-dZIP1 RNAi) dramatically decreased deposit density at 30 dae, which was reduced compared to 25 dae Aβ42 flies. t test, **P < 0.01, ***P < 0.001. Data are expressed as means ± SEM. n = 6 or 8 hemispheres for each genotype. Scale bar: 25 μm. d dZip1 knockdown significantly prolongs the lifespan of Aβ42 flies. The percentage of survivorship was plotted against age (dae). Overexpression of dZIP1significantly shortened the lifespan of Aβ42 (elav-Gal4 > UAS-Aβ42) flies. Decreased dZIP1 levels (Elav-Gal4 > UAS-Aβ42/UAS-dZip1 RNAi) inhibited Aβ42 toxicity in a dose-dependent manner, and dZip1 RNAi #2 showed a more significant phenotype, in which dZip1-RNAi 2# (elav-Gal4 > UAS-Aβ42/UAS-dZip1-RNAi 2#) flies had much more reduced dZIP1 level than that of dZip1-RNAi 1# (elav-Gal4 > UAS-Aβ42/UAS-dZip1-RNAi 1#) flies. The differences shown are all statistically significant (p < 0.001). The reported P values are derived from Mantel-Cox log-rank statistical analysis