Fig. 6: PQBP1 is essential for in vivo activation of microglia by extrinsic Tau.
From: Tau activates microglia via the PQBP1-cGAS-STING pathway to promote brain inflammation
a Protocol of Tau 410 monomer (2.2 μg/μl, 1 μl/injection, 4.4 μg/mouse) or equivalent PBS injection to bilateral entorhinal cortices of non-induced or tamoxifen-induced Pqbp1-cKO mice. Four groups were made for analyses. i.p. intra-peritoneal injection, qPCR quantitative RT-PCR, IHC immunohistochemistry. b Immunohistochemistry of Iba1-positive microglia with PQBP1-Tau colocalization, cGAS-tau colocalization, and NFκB nuclear translocation in injected areas of non-induced Pqbp1-cKO and tamoxifen-induced Pqbp1-cKO. (Right) Quantitative analyses of PQBP1-Tau colocalized microglia, cGAS-tau colocalized microglia, and activated microglia (nuclear NFκB-positive) among Tau-incorporating microglia. N = 5. P value: [Upper] 3.55e−9 (non-induced), 5.71e−9 (Tau410). [Middle] 1.00e−7 (non-induced), 1.00e−7 (Tau410). [Lower] 2.29e−14 (non-induced), 6.98e−12 (Tau410). c RT-qPCR of induction of Tnf and Isg54 by Tau 410 in entorhinal cortex from non-induced or tamoxifen-induced Pqbp1-cKO mice. N = (4, 6, 3, 6). P value: [Upper] 0.0011 (non-induced), 0.0005 (Tau410). [Lower] 0.0031 (non-induced), 0.0080 (Tau410). d Y-maze test at 7, 10, and 14 days and Morris water maze test at 14 days after tau injection into bilateral entorhinal. Data points (Morris water maze test): mean ± SEM. Y-maze: N = (8, 8, 7, 8) for 7 days, (7, 8, 7, 8) for 10 days and (8, 8, 7, 8) for 14 days. Morris water maze: N = (7, 8, 6, 7). P value: [Y-maze; 10 days] 0.0439 (non-induced), and 0.0055 (Tau410). [14 days] 0.0014 (non-induced), and 0.0018 (Tau410). [Morris water maze, Day4] 0.0043 (non-induced), and 0.0048 (Tau410). e In vivo live imaging of microglia by two-photon microscopy with B6.129P2(Cg)-Cx3cr1tm1Litt/J (Cx3cr-1GFP) mice in which microglia were labeled by the endogenous Cx3cr1 enhancer/promoter-driven EGFP protein. f Immunohistochemistry confirmed PQBP1-KD by siRNA-PQBP1 injection. (Graph) Quantification of PQBP1 signal intensity/cell. Data points: mean ± SEM. n = 100 microglia. P = 1.71e−102, **P < 0.01 in two-sided Student’s t-test. Box plots show the median, quartiles, and whiskers that represent data outside the 25th to 75th percentile range. Tuple of N numbers indicates PBS/non-induced, Tau410/non-induced, PBS/induced Pqbp1-cKO, and Tau410/induced Pqbp1-cKO), respectively. For multiple group comparisons, Tukey’s HSD test was performed (##P < 0.01, #P < 0.05).
