Fig. 3: Munc13-1 supramolecular clusters undergo rearrangement in response to stimulation.

a Representative confocal images of Munc13-1 in axonal growth cones of cultured motoneurons before and after Roscovitine (Ros) stimulation. b Graph shows increased Munc13-1 levels in stimulated control (Ctrl) (n = 4 biological replicates) and Smn KO^Rescue motoneurons (n = 3 biological replicates) (***P = 0.0004, ****P < 0.0001; n = 60-82 cells), but not in stimulated Smn KO (n = 4 biological replicates) and Smn KO^{RescueΔ3’UTR} motoneurons (n = 3 biological replicates). c Lattice-SIM shows Munc13-1 supramolecular clusters in presynaptic membranes at axonal growth cones of cultured motoneurons. Inset on the right side: Zoom-in shows colocalization of Munc13-1 with Snap25 in supramolecular clusters. d Upon Roscovitine stimulation, the number of Munc13-1 clusters per growth cone increases in control and Smn KO^Rescue motoneurons, but not in stimulated Smn KO and Smn KO^{RescueΔ3’UTR} motoneurons (from n = 3 biological replicates) (for statistical significance, refer to Supplementary Fig. 3f). Two-tailed Mann-Whitney U test in (b). Source data are provided as a Source Data file.