Fig. 4: JNK activity in early puc expressing neurons affects mitochondrial axonal transport.
a and b Flat-prepped, stage 16 embryos expressing Mito-GFP under the control of the RN2-Gal4 (a) and MzVum-Gal4 (b) lines immunostained for GFP (gray scale - top panels and green - bottom panels) and Fas2 (magenta - bottom panel). The grey rectangle marks the medial part of the ISN, where mitochondrial axonal transport was monitored (see Supplementary Movie 3). Scale bar is 25 µm. c and d Histograms showing mitochondrial density and directional motility in control (grey) versus HepCA expressing (green) aCC/RP2 (c) and VUM motoneurons (d) (n = 9 for RN2 controls, n = 8 for RN2 experimental, n = 9 for MzVum controls and n = 8 for MzVum experimental). Data presented as mean ± SD. Parametric student t-tests were employed. Statistically significant differences were observed between control and JNK overactive neurons for both conditions [RN2 total (*p = 0.0266), RN2 retrograde (p = 0.1884), RN2 paused (p = 0.5501), RN2 anterograde (p = 0.0966), VUMs total (***p < 0.0001), VUMs retrograde (**p = 0.0046), VUMs paused (p = 0.6968) and VUMs anterograde (p = 0.1003). e and f Lifetime range distribution (expressed as per-unit) of motile mitochondria in aCC/RP2 (grey) and HepCA expressing (green) embryos. g and h Mean velocity range distribution (expressed as per-unit) comparison of motile mitochondria in aCC/RP2 (g) and VUMs (h) motoneurons between control (grey) and JNK gain-of-function (green) conditions. For both sets of motoneurons the distribution was shifted to higher velocity classes in JNK hyperactive neurons.
