Journal: The Journal of Neuroscience
Article Title: AMPK Preferentially Depresses Retrograde Transport of Axonal Mitochondria during Localized Nutrient Deprivation
doi: 10.1523/JNEUROSCI.2067-19.2020
Figure Lengend Snippet: Localized substitution of glucose for lactate at the distal axon reduced mean distance of mitochondrial transport events in both directions. A, Representative Western blot image and quantification of group data confirm that neither (AI) phosphorylated AMPK (pAMPK) nor (AIII) total AMPK levels are altered when glucose is substituted for the metabolic equivalent concentration of lactate as the cell's main energy source. AIV, The ratio of pAMPK to total AMPK is also unchanged. Beta-actin serves as a loading control. p > 0.05 (two-tailed unpaired t test). Western blots were prepared from three independent culture preparations. B, Schematic of experimental design. The somatodendritic compartment was exposed to glucose-rich buffer while the axonal compartment was exposed either to buffer containing glucose (15 mm) or the metabolic equivalent concentration of lactate (30 mm). Baseline mitochondrial mobility was measured in the distal axon segment contained in the microgroove (FOV) for 30 min. The kinetics of mitochondrial transport events were compared in axons, which were exposed locally to glucose (Glu) or lactate (Lact) as their main energy source. C, Axons exposed to lactate showed a significantly higher proportion of stationary mitochondria than those exposed to glucose. D, Substitution of glucose with lactate did not affect the proportion of mitochondrial transport events or the velocity (E) in either direction. However, a significant change in the mean distance (F) of mitochondrial movement events in both anterograde and retrograde directions was noted. *p < 0.0001 (two-tailed unpaired t test). n ≥ 21 from at least five independent culture preparations.
Article Snippet: Stationary mitochondria were classified on each kymograph by identifying vertical lines using a MATLAB (R2017a) self-written function, the code for which is available at https://github.com/niamhconno/Watters-et-al-2020-jNeurosci .
Techniques: Western Blot, Concentration Assay, Control, Two Tailed Test