Fig. 1

Inhibition of NAMPT or SIRT2 suppresses the proliferation of human iPS cells by enhanced apoptosis and cell cycle arrest. a Schematic of the NAMPT-NAD⁺-SIRT2 pathway. NAMPT is the rate-limiting enzyme that converts nicotinamide (NA) into NAD⁺ that subsequently activates the NAD⁺ dependent protein deacetylase, SIRT2. Specific small molecule inhibitors for NAMPT (FK866) and SIRT2 (AC93253) are depicted in red. b 5 × 10⁴ human iPS cells were seeded on a Geltrex-coated 6-well plates, as described in MM. After 48 h of culture, different doses of FK866 or AC93253 were added to the culture medium. DMSO was used as vehicle control. Cell numbers were counted after 48 h of culture. c Numbers of viable iPS cells treated with FK866 (left) or AC93253 (right) were quantified using trypan blue dead cell exclusion. DMSO was used as vehicle control. Fold change differences of live cells relative to DMSO-treated cells are shown. Data represent means ± SD from two independent experiments, each in triplicates (*p < 0.05, ***p < 0.001, ****p < 0.0001). d Representative images of human iPS cells treated with DMSO, FK866, or AC93253 for 48 h. Scale bars: 50 μm. e Analysis of apoptosis of FK866 (left) or AC93253 (right)-treated human iPS cells using Annexin V assay. DMSO was used as vehicle control. Diagrams show the fold change differences in the percentage of each cell fraction (early apoptosis, late apoptosis, viable cells) relative to DMSO-treated cells. Data represent means ± SD from two independent experiments, each in triplicates (***p < 0.001, ****p < 0.0001, compared to DMSO-treated cells). f Analysis of cell cycle of FK866 (left) or AC93253 (right)-treated human iPS cells using BrdU assay. DMSO was used as vehicle control. Data represent means ± SD from two independent experiments, each in triplicates, (*p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001)