Figure 1.
Increased membrane-bound PrPc levels are associated with Fyn activation in AD. A, Representative Western blot (WB) for PrPc, Fyn, pY416-Fyn, and NeuN in 10 of 84 specimens of NCI (N), MCI (M), and AD (A) composing our cohort. PrPc, Fyn, and α-tubulin were measured by direct WB, while pY416-Fyn levels were estimated following total Fyn immunoprecipitation. B–D, Box plots for PrPc (B), Fyn (C), and pY416-Fyn (D) protein levels in the MB fraction of NCI, MCI, and AD groups. Total Fyn levels were unchanged, whereas the levels of its active phosphorylated form, pY416-Fyn, were increased in the AD group compared with NCI and MCI [Kruskal–Wallis followed by Mann–Whitney's U test and Bonferroni's correction (p < 0.05)]. E, F, Linear regression analyses between PrPc/Fyn (E) and PrPc/pY416-Fyn (F) protein levels (Spearman's rank correlation). PrPc and total Fyn showed a strong association regardless of clinical status (E). In contrast, a significant positive correlation was only found in the AD group linking activated Fyn and PrPc levels. In the figure legends, the italicized numbers between parentheses indicate group sizes. NCI is shown in green, MCI in yellow/orange, and AD in red. In box plots, the bar inside the box indicates the median; the upper and lower limits of boxes represent the 75th and 25th percentiles, respectively; and the bars flanking the box represent 95th and 5th percentiles. *p < 0.05; **p < 0.01. EC, extracellular-enriched fraction; IC, intracellular-enriched fraction; MB, membrane-associated fraction; Tg, transgenic; DLU, densitometry light unit; A.U., arbitrary unit.