Fig. 2: Spatial compartmentalization of neuronal mitochondria–lysosome contact dynamics.

a Representative time-lapse confocal images of contacts between mitochondria (red, Mito-RFP) and lysosomes (green, Lyso-GFP) in soma, dendrites, and axons of wild-type human dopaminergic iPSC-derived neurons. Time-lapse recordings were taken at 2 s intervals for 5 min. Yellow arrows mark stable M–L contacts. White arrows mark the site of M–L contacts before contact formation or after contact untethering. Black line shows duration of contacts. Scale bar = 500 nm (see Supplementary Movies 4–6). b Representative frames of live-cell imaging (left) and dual color kymographs (right) of M–L contacts in dendrites and axons (mitochondria: red, Mito–RFP; lysosomes: green, Lyso-GFP). In confocal image frames (left), contact sites are denoted by yellow arrows. In kymographs: white scale bar = 1 μm, yellow vertical bar = 30 s. Yellow arrows in kymograph point to start and end timepoints of M–L contact tethering. Left black line shows duration of contacts. c, d Quantification of M–L contacts across different neuronal compartments. One-way ANOVA followed by Tukey’s multiple comparisons test. c Comparison of average minimum durations of M–L contacts in soma, dendrites, and axons (n = 86 (soma), n = 35 (dendrite), n = 34 (axon) contacts from 26 neurons, N = 3 independent experiments), *p = 0.0335. d Percentage of lysosomes contacting mitochondria in soma, dendrites, and axons (for >20 s) (n = 14 (soma), n = 13 (dendrite), n = 14 (axon) neurons; N = 3 independent experiments). For all quantifications, data are means ± S.E.M; *p ≤ 0.05, ns: not significant.