JNK3 indeed phosphorylates APP at T668P in FAD brains, without affecting the total APP protein levels ( Figure 5G): while the human APP levels in whole-cell

lysates were not very different between FAD:JNK3+/+ and FAD:JNK3−/− mice, p-T668P signals as well as human APP protein levels were significantly reduced when membrane fractions were analyzed ( Figure 5G). It should be noted that sw192 antibody is specific to Swedish mutation in human APP ( Haass et al., 1995), thus it was used as a marker for FAD mice. In particular, p-T668P levels in membrane fractions were reduced to a much greater extent in α and β CTF than in the full-length APP with JNK3 deletion. This finding closely parallels the observation in human AD brains, wherein increased T668P phosphorylation mainly associated with α and β CTF and not the full-length APP ( Lee et al., 2003). In addition, total protein levels of α and β CTF were also reduced to a much CSF-1R inhibitor greater extent than those in the full-length APP in the membrane fraction ( Figure 5G). These results correlate faithfully with our Aβ42 Elisa results at 6 months. We therefore interpret these results as suggesting that JNK3 phosphorylates APP preferentially in membranous compartments, such as vesicles/endosomes,

thereby promoting APP processing. It should be noted that although BACE1 and PS1 levels were increased in FAD mice compared to those in normal mice as reported ( O’Connor Paclitaxel in vitro et al., 2008), JNK3 deletion did not affect their levels greatly ( Figure 5H). Similarly, neither the levels nor the extent

of tau phosphorylation old was altered by JNK3 deletion in FAD mice (data not shown). In a preliminary RNaseq-based transcriptome analysis of 3-month-old FAD mice with and without JNK3 and the control cortices from JNK3+/+ and JNK3−/− mice, we obtained the results that suggest that there is a general translational block in FAD:JNK3+/+ mice; genes involved in translation, such as ribosomes and translation-initiation factors, were dramatically reduced in FAD:JNK3+/+ compared to JNK3+/+ mice and JNK3 deletion restored the effect on these genes to nearly normal levels (data not shown). We therefore tested whether there is indeed a global translational block in FAD mice by western blotting cortical lysates with an antibody against phospho-S6235/236 ribosomal protein, a marker for active translation. Indeed, the p-S6 signal was reduced by 48% in FAD: JNK3+/+ mice, compared to that in the normal mice and FAD:JNK3−/− mice ( Figures 6A and 6B). Immunohistochemistry with p-S6 antibody also revealed similar findings: both the number of cells that are positive for p-S6 signals and the intensity of its signals decreased significantly in the cortex of FAD:JNK3+/+ mice, compared to those in other genotypes ( Figure 6C). It should also be pointed out that p-RaptorS792 levels were increased by 4-fold in FAD:JNK3+/+ compared to those in FAD:JNK3−/− ( Figures 6A and 6B).