Figure 5: Aβ increases acetylated tau and induces missorting of tau.
From: HDAC6 and RhoA are novel players in Abeta-driven disruption of neuronal polarity
(a) Representative immunoblot showing acetylation of tau immunoprecipitated from lysates of cortical neurons treated with either 0.05% DMSO (ctrl), 100 nM Aβ (Aβ 0.1), 1 μM Aβ (Aβ 1.0) or 100 nM TSA. Immunoprecipitated tau (bottom panel) was overlaid for acetylated lysine (top panel). (b) Quantification of the ratio between the protein level of acetylated tau and total tau in tau immunoprecipitates from neurons treated with either 0.05% DMSO (ctrl, 1.00±0.00, n=7), 100 nM Aβ (Aβ 0.1, 1.42±0.17, n=5), 1 μM Aβ (Aβ 1.0, 1.34±0.18, n=4) or 100 nM TSA (TSA, 2.22±0.52, n=7). Statistical significance determined by two-tailed t-test. Ctrl/Aβ 0.1:*P=0.012; ctrl/Aβ 1.0: *P=0.030; ctrl/TSA: *P=0.038. (c) Immunofluorescence analysis of tau localization (blue) in FLAG/GFP or HDAC6-FLAG/GFP-electroporated neurons (green), treated with either 0.05% DMSO (ctrl), 100 nM Aβ (Aβ) or 10 μM tubacin (tubacin), showing missorting of tau in minor neurites in the presence of Aβ, which is prevented by HDAC6 overexpression. Note, in the bottom panels showing neurons treated with Aβ, the presence of a non-electroporated neuron showing unpolarized tau staining (white arrow), and a neighbouring neuron overexpressing HDAC6 showing polarization of tau. Scale bar, 25 μm. Enlarged images of merged channels (far-right panels) showing minor neurites close to the cell body. Scale bar: 5 μm. (d) Quantification of the percentage of neurons showing polarized immunostaining of tau in axons, in neurons electroporated with FLAG/GFP and treated with either 0.05% DMSO (FLAG ctrl, 78.66±1.95, n=91), 100 nM Aβ (FLAG Aβ, 29.26±4.16, n=94), 10 μM tubacin (FLAG tubacin, 24.75±2.53, n=20) or electroporated with HDAC6-FLAG/GFP and treated with 0.05% DMSO (HDAC6 ctrl, 85.00±5.00, n=25) or 100 nM Aβ (HDAC6 Aβ, 64.32±0.68, n=31). Statistical significance determined by one-way ANOVA, ***P<0.001. In b and d, data are expressed as mean±s.e.m. and as mean percentage±s.e.m., respectively. ANOVA, analysis of variance.
