Figure 1: Extracellular Aβ induces neurite retraction via ROCK-dependent pathway.
From: HDAC6 and RhoA are novel players in Abeta-driven disruption of neuronal polarity
(a) Bar graph showing the mean axonal length of neurons incubated either with 0.05% DMSO (ctrl, 98.79±4.44, n=134) or with 1 μM Aβ (Aβ, 67.51±2.77, n=159) for 1 h, measured by axon tracing. Statistical significance determined by two-tailed t-test, **P<0.001. (b) Fluorescence analysis of tau (green) and tubulin-βIII (blue) localization in cultured hippocampal neuron at 3 DIV, showing tau polarization in axons. Scale bar, 25 μm. (c) Images taken at 0, 15, 30 and 40 min from time-lapse movies of embryonic hippocampal neurons in the presence of optically driven microspheres coated with scrambled Aβ (top panels), Aβ (middle panels), with Aβ and 10 μM Y27632, a ROCK inhibitor (lower panels), or with Aβ and 10 μM blebbistatin, a myosin II inhibitor. The growth cone area (highlighted in yellow) shows a reduction upon contact with the Aβ-coated microsphere that is prevented by Y27632 and by blebbistatin. Scale bar, 25 μm. (d) Confocal image showing successful coating of microspheres with fluorescently labelled Aβ peptide. Scale bar, 1 μm. (e) Bar graph showing the ratio between the growth cone area at the end and that at the start of time-lapse movies as in c. Scrambled Aβ (ctrl, 1.05±0.11, n=6), Aβ (Aβ, 0.43±0.04, n=7), Aβ+10 μM Y27632 (Aβ +Y27632, 0.93±0.24, n=4) and Aβ+10 μM blebbistatin (Aβ+blebb, 0.70±0.07, n=3). Statistical significance determined by two-tailed t-test, **P<0.001 (ctrl/Aβ), *P=0.034 (Aβ/Aβ +Y27632), *P=0.009 (Aβ/Aβ+blebb). In a and e, data are expressed as mean±s.e.m.
