Figure 1.

Annonacin causes a concentration-dependent cell death and redistribution of tau from the neurites to the cell body of neurons from embryonic rat striatum in culture. A, Representative photomicrographs of cultured neurons treated for 48 h with increasing concentrations of annonacin (Anno) and labeled with the antibody AD2 raised against pS396/pS404-tau (red). Nuclei are stained with 4′,6′-diamidino-2-phenylindole (DAPI; blue). Arrows show neurons with intact nuclear morphology and perinuclear AD2 immunoreactivity. B, Quantification of neuronal survival (percentage of untreated control cultures) and of neurons with AD2 immunoreactivity in the cell body (percentage of all neurons per culture well) after 48 h of annonacin treatment. ***p < 0.001 versus control. C, The redistribution of tau (arrows) in cultured neurons treated with 50 nm annonacin for 48 h is also detected by other antibodies against phosphorylated epitopes of tau: anti-AT8 raised against pS202/pT205-tau, anti-AT100 raised against pT212/pS214-tau, and anti-AT270 raised against pT181-tau (red). Nuclei are stained with DAPI (blue). Scale bars: A, C, 20 μm.