Research Paper Volume 7, Issue 3 pp 152—166
Serum from calorie-restricted animals delays senescence and extends the lifespan of normal human fibroblasts in vitro
Figure 4. SIRT1 protein levels in normal human diploid fibroblasts decrease with increasing passage number and CR treatment retards this effect.
(A) Representative immunoblots for SIRT1 (upper panels) and β-actin (lower panels) proteins from IMR-90 cells (left panel) and WI-38 cells (right panel) at different passage number. (B) Quantification of SIRT1 protein levels shown in (A), after correction for β-actin loading controls. Data represent the average -/+ SEM from three independent experiments; *= statistically significant (p<0.05). (C) Representative immunoblots of SIRT1 (upper panels) and β-actin (lower panels) proteins from IMR-90 cells at PDL 32 and PDL 45 (left panels) and WI-38 cells at PDL 37 (right panels) cultured for one week in media containing 10% CR or AL serum. (D) Quantification of SIRT1 protein levels shown in (C), after correction for β-actin loading control. Data represent the average -/+ SEM from three independent experiments (*and #= statistically significant (p<0.05) for PDL effect and CR vs. AL effect, respectively).