Fig. 4.

Tau competes with CX3CL1 for binding to CX3CR1. a-b Representative images of Tau-Cy5 attached to the surface of WT (a) and KO (b) microglia after treatment with Tau-Cy5 for 5 min at 4 °C. c Quantification of Cy5 fluorescence intensity on the microglial surface. In the absence of CX3CR1, the levels of Tau-Cy5 on the membrane of microglial cells are markedly reduced. d Tau profile in the competition assay between Tau and CX3CL1 detected with anti-Tau5. Note that the profiles indicate that the binding of Tau to the column was weaker in the presence of CX3CL1. e-g In vitro competition assay performed in primary microglial cell culture. Representative images and quantification of Cy5 fluorescence intensity (red) and Iba1 (green) in cells treated with Tau-Cy5 in the absence (c) or presence (d) of CX3CL1. As shown, Tau internalization is reduced in the presence of CX3CL1. Bars show means ± S.E. ∗∗∗p ≤ 0.001. White scale bar: 100 μm, purple scale bar: 50 μm