Fig. 2

rl (dERK) is upregulated in TDP-43 flies and downregulation of the fly MEK/ERK pathway suppresses TDP-43 toxicity. a-b’ TDP-43-induced eye degeneration (by GMR-Gal4) is suppressed by transgenic RNAi KD of rl. RNAi-mCherry flies are used as the control for RNAi-rl. c The degeneration scores in (a-b’) are quantified and shown as violin plots with mean. d qPCR analysis of the KD efficiency of RNAi-rl. Note that the rl mRNA levels are not fully decreased because the RNAi-rl transgene is expressed in the fly eye only (with GMR-Gal4), while the mRNA levels are examined in the homogenates of the entire fly head that includes many other cells expressing rl but not RNAi-rl. e Adult-onset neuronal downregulation of rl (by elavGS) suppresses TDP-43-induced, age-dependent climbing decline. f Neuronal upregulation of rl abolishes the suppressive effect of RNAi-Dsor1 (dMEK) on TDP-43-induced climbing defects. g-h qPCR analysis of the mRNA levels of Dsor1 (g) and rl (h) in TDP-43 fly heads. All mRNA levels are normalized to actin and shown as percentages to that of the respective control flies (which is set to 100%): RNAi-mCherry in (d) and UAS-lacZ in (g-h). i-p Representative western blot images (i, m) and quantifications of the relative dERK protein levels (j, n) as well as phosphorylated dERK (p-dERK) levels normalized to total dERK (k, o) or GAPDH (l, p) in the “elavGS > hTDP-43” (i-l) or the “elavGS > hTDP-43 + RNAi-Dsor1” (m-p) fly heads are shown. Of note, because the anti-ERK and the anti-pERK antibodies are both of the rabbit origin, for western blotting of ERK and pERK in this study, equal amounts of the same samples were examined on two parallel gels. Mean ± SEM; n = 10 eyes/group in (c), n = 3 in (d, g-h, j-l, n-p), and n =  ~ 10 vials/group with ~ 20 flies each vial in (e–f). Student’s t-test except for one-way ANOVA in (f). *p < 0.05, **p < 0.01, ***p < 0.001; ns, no significance. Scale bar: 100 μm