Figure 1.

Tau is correlated with accumulation of ubiquitin and activation of PERK. A, Representative Western blots of ubiquitin and pPERK and PERK in the brains of 9-month old Tg and nontransgenic (Non) controls. Tau bands confirm tau overexpression; GAPDH was used as a loading control. B, Quantification of A (n = 6 Non and n = 7 Tg; 4- and 3-fold increases of **p < 0.01 and *p < 0.05, respectively). C–J, Representative immunofluorescent microscopy images of ubiquitin (C,D; green), pPERK (E,F; red), BiP (G,H; red), and tau (I,J; green) in the hippocampus of Non (C,E,G,I) and Tg (D,F,H,J) mice. DAPI (blue) was used to identify cell nuclei. Scale bar, 20 μm. K, Graph showing quantification of immunofluorescent-positive signal in C–J. Ubiquitin, pPERK, and BiP levels in the Tg brains were increased by 3.7-fold (n = 3 Non and n = 6 Tg; ***p < 0.001), 2.4-fold (n = 3 Non and n = 5 Tg; ***p = 0.0001), and 0.3-fold (n = 5 Non and n = 4 Tg; *p < 0.05), respectively; PHF1 tau levels were virtually undetectable above background in I. Statistical significance was determined using Student's t test.