Fig. 5

Dynamic assembly of axonal rough ER is defective in Smn-deficient motoneurons. a Smn+/+;SMN2tgtg and Smn−/−;SMN2tgtg motoneurons expressing mCherry-KDEL were immunostained against mCherry-KDEL, Y10B and eEF2. White boxes indicate enlarged ROIs within growth cones. BDNF stimulation induces formation of Y10B/eEF2 co-clusters within 10 s as well as 1-min in control, but not in Smn-deficient motoneurons. b Quantification of Y10B/eEF2 co-clusters that are representative of ribosomes in the elongation phase of translation. In contrast to control motoneurons (**P = 0.0023; ****P < 0.0001; n = 30–37 cells), Smn−/−;SMN2tgtg motoneurons do not show an increase in the number of Y10B/eEF2 co-clusters in growth cones (n.s., P > 0.9999; n = 29–31 cells from 3 independent experiments). c Quantification of Y10B/eEF2 co-clusters that colocalize with ER after BDNF pulse application. The number of Y10B/eEF2/ER co-clusters increases within 10 s and 1-min poststimulation in control (***P = 0.0002; ****P < 0.0001; n = 28–37 cells), but not in Smn−/−;SMN2tgtg motoneurons (n.s., P = 0.8953; n = 23–29 cells from 3 independent experiments). In all graphs, the average number of co-clusters is shown per growth cone. All representative images are from maximum projection of five 0.12-µm z-stacks. Data are presented in scatter dot plot; error bars represent mean ± SEM. Statistical analyses were done by one-way ANOVA with Dunn’s post-hoc test