Fig. 7.

Increased DNA content in SirT1-deficient cells suppressed by the additional disruption of Parp-1. A FACS analysis of Parp-1^+/+; SirT1^+/+, Parp-1^+/+;SirT1^−/−, Parp-1^+/−;SirT1^−/−, and Parp-1^−/−;SirT1^−/− cells. The right hand part shows the identification of cells in G2/M by phosH3S10 staining versus DNA content. The majority of Parp-1^+/+;SirT1^−/− cells display an increased DNA content compared to the control Parp-1^+/+;SirT1^+/+ or the Parp-1^+/−;SirT1^−/− and Parp-1^−/−;SirT1^−/− cells. Some Parp-1^−/−;SirT1^−/− cells also evidence a lower DNA content. The profiles shown are representative of three independent experiments. B Karyotype analysis showing a significantly increased chromosome number in Parp-1^+/+;SirT1^−/− cells (b) compared to the control Parp-1^+/+;SirT1^+/+ (a) or the Parp-1^+/−;SirT1^−/− (c) and Parp-1^−/−;SirT1^−/− cells (d). At least 30 individual metaphases were counted per cell line. The mean value (±SD) of three independent experiments is shown on the histogram bars. The range of chromosome numbers is indicated on the top. Note, the identification of Parp-1^−/−;SirT1^−/− cells with a reduced number of chromosomes (n = 38) compared to Parp-1^+/+;SirT1^+/+ cells (n = 50). P value was calculated by ANOVA test: ***P < 0.001