Fig. 5: Tau phosphorylation affects envelope functionality in vitro.
From: Tau phosphorylation impedes functionality of protective tau envelopes
a, Schematics and multichannel fluorescence micrographs of 120 nM phospho-tau on GMPCPP (red) and GMPCPP-capped GDP (green) microtubules. MT, microtubule. Here, 100 nM katanin–GFP was added at t = 0 min in the presence of tau, leading to severing of GMPCPP microtubules while GDP microtubules remained protected. Experiments were performed six times for both dephospho-tau and phospho-tau, yielding similar results. Scale bar, 2 μm. b, Normalized microtubule density over time for GMPCPP (red) and GDP (green) microtubules covered by phospho-tau envelopes after the addition of katanin at t = 0 s. Data of GMPCPP and GDP microtubules are presented as the mean (center line) ± s.d. (shaded area) (n = 25 and 40 microtubules, respectively, in six independent experiments). c, Normalized microtubule density over time as in b, but with dephospho-tau envelopes. Data of GMPCPP and GDP microtubules are presented as the mean (center line) ± s.d. (shaded area) (n = 9 and 29 microtubules, respectively, in six independent experiments). d, Fluorescence micrographs of 30 nM dephospho-tau (left; cyan) or 120 nM phospho-tau (right; magenta) on GMPCPP (red) and taxol-stabilized (blue) microtubules. Here, 500 nM katanin–GFP was added at t = 40 s, leading to GMPCPP microtubules severing while taxol-stabilized microtubules remained protected. Katanin severing eventually led to disassembly of envelope-covered portions of taxol-stabilized microtubules mainly from their boundaries (orange arrows), with occasional katanin severing within a tau envelope (white arrow). Experiments were performed ten (dephospho-tau) and eight (phospho-tau) times, yielding similar results. Scale bars, 2 μm. e, Normalized microtubule density over time for taxol-stabilized microtubules covered with either 120 nM phospho-tau (magenta) or 30 nM dephospho-tau (cyan). Data for phospho-tau and dephospho-tau are presented as the mean (center line) ± s.d. (shaded area) (n = 12 and 19 microtubules, respectively, in eight and ten independent experiments). f, Normalized microtubule density over time for GMPCPP microtubules covered with either 120 nM phospho-tau (magenta) or 30 nM dephospho-tau (cyan). Data for phospho-tau and dephospho-tau are presented as the mean (center line) ± s.d. (shaded area) (n = 16 and 28 microtubules, respectively, in eight and ten independent experiments).
