Fig. 6

SIRT1 increases cleaved caspase 3 and PARP while decreasing full-length forms of these pro-apoptotic proteins. A-D Cells were treated with either control media or SRT2104 (50 μmol/L) for 24 h and 48 h or with Staurosporine (STS, 50 nmol/L) for 2 h (A-D). F Cells were transfected with 10 nmol/L of either scrambled siRNA (siNC) or SIRT1 siRNA (siSIRT1). At 6 and 24 h post-transfection, the media were changed, and protein was extracted at 48 h post-transfection. Full-length caspase 3 and cleaved caspase 3 protein levels (A and B, respectively), full-length PARP and cleaved PARP (C and D, respectively), were determined in cell extracts by specific antibodies in western blotting; cropped images representative of western blots are presented (E). Densitometric quantifications are relative to cells cultured in control media or transfected with siNC and normalized relative to the abundance of total MAPK (p44/42; loading control). The results are presented as the means ± SEM from 4 independent experiments. Asterisks indicate significant differences from their respective controls (*p < 0.05, ** p < 0.01, ***p < 0.001)