Fig. 3

Active calpain-1 amounts are elevated early in AD and are sustained throughout disease progression. a Representative blots of cortical homogenates from postmortem brain. Blots were probed with antibodies to detect active calpain-1 at 76 kDa and active/cleaved caspase-3 at 19 kDa. An antibody against calpastatin (CAST) was used to detect CAST holoprotein at 110 kDa, active CAST at > 25 kDa and inactive CAST at < 25 kDa. An antibody against α-spectrin was used to detect holoprotein at 240 kDa, calpain- and caspase-cleaved fragments at 140 to 150 kDa and caspase-cleaved fragments at 110 to 130 kDa. Blots were also probed with an antibody against neuron-specific enolase (NSE, 45 kDa) as a loading control. Bar graphs show amounts of (b) active calpain-1 relative to NSE in each sample, (c) active CAST and (d) inactive CAST both as a proportion of total CAST (e) active caspase-3 relative to NSE, (f) caspase- and calpain- cleaved 140–150 kDa α-spectrin fragments and (g) caspase-cleaved 110–125 kD α-spectrin fragments, both standardized to NSE. CTRL: control (n = 5), Braak II AD (n = 4), Braak III AD (n = 3), Braak IV AD (n = 4), Braak V AD (n = 3), Braak VI AD (n = 5). Data is mean ± SEM. *p < 0.05, **p < 0.01, ***p < 0.001