Figure 3. Fibroblasts from longer-lived species of primates have increased mRNA expression of PSMB8 compared with those from shorter-lived species but no significant change in mRNA for PSMB5; fibroblasts from long-lived primates are also more responsive to IFN-γ signaling and have elevated expression of IFNGR2, relative to those from short-lived species.

(A) Scatter plot of relative PSMB8 mRNA levels. (B) Scatter plot of relative PSMB5 mRNA levels. (C) Scatter plot of PSMB8 mRNA levels following 24 hours exposure to 40 ng/ml of IFN-γ, as a percentage of PSMB8 mRNA in cells incubated without IFN-γ. (D) Plot of L’Hoest’s monkey (MLS 24.1 yr) cell viability, following exposure to a range of doses of H₂O₂, with or without a 24-hour incubation with 40 ng/ml of IFN-γ. (E) Plot of gorilla (MLS 55.4 yr) cell viability, following exposure to a range of doses of H₂O₂, with or without 24-hour incubation with 40 ng/ml IFN-γ. Error bars represent SEM of 6 replicate wells at each H₂O₂ concentration. (F) Scatter plot of the change in H₂O₂ dose required to reduce cell viability to 50% under incubation for 24 hours with 40 ng/ml of IFN-γ. Raw values are shown in Supplemental Figure 6. Statistical significance was established using simple linear regression analysis.