Fig. 7
Significant changes in enzymes of the Ras/mitogen-activated protein kinase kinase (MEK)/extracellular signal-regulated kinase (ERK) signaling pathway and glycogen synthase kinase 3β (GSK3β) following DNA amyloid-β 1–42 peptide (Aβ42) immunization. Equal amounts of proteins from soluble brain lysates of 20-month-old triple-transgenic Alzheimer’s disease (3xTg-AD) mice (D1–D7 = DNA Aβ42-immunized mice, C1–C7 = 3xTg-AD control mice, wt = wild-type control mice) were separated by SDS-PAGE, blotted onto nitrocellulose filters, and probed using antibodies specific for MEK (a, upper panel) and its active form phosphorylated MEK (a lower panel), total ERK1/2 (b, upper panel) and the phosphorylated forms of ERK1/2 (b lower panel), and GSK3α/β (c, upper panel) and activated GSK3β (c, lower panel). Of note, a blot with GSK3α/β is shown in the comparison for activated GSK3β because it appears that there was weak cross-reactivity of this specific antibody with both GSK3 bands (c, lower panel), but differences were seen only for the strong reactivity with GSK3β phosphorylated at residue Y216 (46 kD band). As a loading control, the blots were reprobed with the housekeeping protein β-tubulin (d). All assays were performed three times in independent experiments. Shown are representative results from one of these assays