Figure 7. Rapamycin treatment attenuates loss of RPE-characteristic markers, RPE cell growth, and photoreceptor dysfunction in RPEΔMT mice.

(A) An immunoblot shows reduced phosphorylation of P70SK6^Thr389 and S6^Ser235/236 in both control and RPEΔMT mice after rapamycin treatment. (B and C) Immunostaining for p-S6^Ser235/236 (green) and cre (red) shows reduced reactivity of p-S6^Ser235/236 in cre-expressing RPE cells in rapamycin-treated (C) versus vehicle-treated (B) RPEΔMT mice. Rapa, rapamycin. Original magnification, ×400. (D) Rapamycin treatment normalizes cellular protein content in RPEΔMT mice (R + rapa) at 16 weeks of age (triplicates). (E) The percentage of RPE with normal thickness (2.5–5 μm) is significantly increased in rapamycin-treated RPEΔMT mice at 22 weeks (n = 5), compared with that in vehicle-treated RPEΔMT mice (n = 3). (F) An immunoblot demonstrates the normalizing effect of rapamycin on the levels of RPE characteristic proteins and AIF in RPE cells from 16-week-old RPEΔMT mice. (G and H) RPE65 reactivity (red) is preserved in RPEΔMT mice by rapamycin treatment (H). Original magnification, ×200. (I) Quantification of proteins (triplicates) detected by immunoblot (e.g., F) shows rapamycin-induced increases in several RPE-characteristic markers in RPEΔMT RPE cells (normalized to vehicle-treated control mice). (J) Rapamycin treatment of RPEΔMT mice (n = 6) preserves cone density at 22 weeks, compared with that of vehicle-treated RPEΔMT mice (n = 3). (K) Electroretinography demonstrates significantly increased scotopic responses in 22-week-old RPEΔMT mice treated with rapamycin (n = 5), compared with those of vehicle-treated RPEΔMT mice (n = 4). Verticle bars clarify the 2 groups of values used for statistical comparison. Data represent mean ± SEM. *P < 0.05; ^§P < 0.01.