Figure 1. Depolarization-induced influx... | Rockefeller University Press

Figure 1.

Depolarization-induced influx of Zn2+, not Ca2+, arrests axonal transport of lysosomes. (A) Representative kymographs (left) and measured tracks (identified using KymoButler; right) of LAMP1-mCherry motility along axons from primary cultured rat hippocampal neurons prior to (“baseline”; top) or after initiation of Zn2+ influx induced by 50 mM KCl depolarization (middle), and then following washout and addition of 100 µM TPEN (bottom). (B) Mean instantaneous speed (±SEM) of lysosomes moving retrograde (blue) or anterograde (green) across baseline, Zn2+ influx by 50 mM KCl depolarization, and TPEN treatment (60-s binned, representing 10 axons). (C) Mean speed (±SEM) of lysosomes moving in the indicated directions for each condition (n = 10 axons from six independent replicates). Least-squares regression with post-hoc Tukey HSD. (D) Proportions of lysosomes moving in the indicated directions across baseline, depolarization, and TPEN treatment (60-s binned, representing 10 axons). (E) Mean proportions of lysosomal motility for each condition. (F) Mean instantaneous speed (±SEM) of lysosomes moving retrograde (blue) or anterograde (green) across baseline, 2 mM Ca2+ influx by 50 mM KCl depolarization, and washout (60-s binned, representing 10 axons). (G) Mean speed (±SEM) of lysosomes moving in the indicated directions for each condition (n = 10 axons from six independent replicates). Least-squares regression with post-hoc Tukey HSD. (H) Proportions of lysosomes moving in the indicated directions across baseline, 2 mM Ca2+ with 50 mM KCl, and washout (60-s binned, representing 10 axons). (I) Mean proportions of lysosomal motility for each condition. **** P < 0.0001, *** P < 0.001, ** P < 0.01, * P < 0.05, n.s. not significant.

Depolarization-induced influx of Zn ²⁺ , not Ca ²⁺ , arrests axonal transport of lysosomes. (A) Representative kymographs (left) and measured tracks (identified using KymoButler; right) of LAMP1-mCherry motility along axons from primary cultured rat hippocampal neurons prior to (“baseline”; top) or after initiation of Zn²⁺ influx induced by 50 mM KCl depolarization (middle), and then following washout and addition of 100 µM TPEN (bottom). (B) Mean instantaneous speed (±SEM) of lysosomes moving retrograde (blue) or anterograde (green) across baseline, Zn²⁺ influx by 50 mM KCl depolarization, and TPEN treatment (60-s binned, representing 10 axons). (C) Mean speed (±SEM) of lysosomes moving in the indicated directions for each condition (n = 10 axons from six independent replicates). Least-squares regression with post-hoc Tukey HSD. (D) Proportions of lysosomes moving in the indicated directions across baseline, depolarization, and TPEN treatment (60-s binned, representing 10 axons). (E) Mean proportions of lysosomal motility for each condition. (F) Mean instantaneous speed (±SEM) of lysosomes moving retrograde (blue) or anterograde (green) across baseline, 2 mM Ca²⁺ influx by 50 mM KCl depolarization, and washout (60-s binned, representing 10 axons). (G) Mean speed (±SEM) of lysosomes moving in the indicated directions for each condition (n = 10 axons from six independent replicates). Least-squares regression with post-hoc Tukey HSD. (H) Proportions of lysosomes moving in the indicated directions across baseline, 2 mM Ca²⁺ with 50 mM KCl, and washout (60-s binned, representing 10 axons). (I) Mean proportions of lysosomal motility for each condition. **** P < 0.0001, *** P < 0.001, ** P < 0.01, * P < 0.05, n.s. not significant.