Figure 4. HDAC7 but not HDAC2 re-expression allows to resume proliferation in pre-senescent cells. Pre-senescent AG04431 HDFs, i.e. cells at few passages from the onset of replicative senescence, were transduced with lentiviruses expressing EGFP (pLV EGFP), HDAC2 (pLV HDAC2) or HDAC7 (pLV HDAC7). (A) Representative Western blots showing HDAC2 and HDAC7 expression after transduction. GAPDH was used as a loading control. (B) Quantification of the relative protein abundance of HDAC2 and HDAC7. Signal intensities were quantified and normalized relative to the abundance of GAPDH and are expressed relatively to the control condition (CTL). (C) Representative growth curves of the cells with indicated conditions. The passages studied are indicated by an arrow. (D) Representative confocal images of cells labelled with Ki-67 staining (red) and DAPI (nucleus staining, blue) (scale bar = 50 μM). (E) Percentage of Ki-67-positive cells. (F) Percentage of SA-βgal positive cells. (G) Steady-state mRNA level of IL-6, IL-8, MMP-1 and MMP-3. GAPDH was used as housekeeping gene. Results were expressed as fold induction in comparison with the control condition. Statistical analyses were performed using an ANOVA I (*: p<0.05; **: p<0.01).