Caspase-Mediated Truncation of Tau Potentiates Aggregation
Figure 4
Validity of GFP as an N-terminal marker of tau. (a) presents representative immunoblots of lysates from cell expressing GFP-3PO without any treatment and with treatment of either staurosporine or Z-VAD-fmk as indicated. Blots were probed with anti-GFP or Tau12 (aa9–18) to show N-terminal truncation of tau upon pharmacological manipulation of caspase activity. Migration of molecular weight standards is indicated on the left of each blot. Note the absence of anti-GFP specific band(s) absent in Tau12 blots. The accompanying graphs presents the mean intensities (±SEM) derived from 3 immunoblots. The relative intensities of the uppermost bands from anti-GFP and Tau12 were normalized to that of their respective untreated controls. Staurosporine decreased tau levels in both GFP and T12 blots. Z-VAD-fmk statistically increased tau levels as indicated by anti-GFP and displayed a trend towards significance by Tau 12 (, Student t-test). An asterisk indicates a statistical difference (; Student’s t-test). (b) presents double immunofluorescent staining of cells untreated or treated with either Z-VAD-fmk or staurosporine as indicated. The bar represents 20 μm. Note the identical colocalization pattern between anti-GFP and Tau12 stainings regardless of pharmacological manipulation of caspase activity.