Figure 6. SIRT1 regulates expression of α7 nAChR and αAPP by SH-SY5Y/APPswe cells through the MAPK pathway. Transfection with SIRT1 siRNA reduced the level of both SIRT1 protein (A) and mRNA (B), as determined by western blotting and qRT-PCR, respectively. (C) Knock-down of SIRT1 reduced the level of α7 nAChR protein. (D) Knock-down of SIRT1 reduced the level of p-ERK1/2 protein. After 24 h of transfection, the cells were treated with 10 μM U0126 for 2 hr and the levels of p-ERK1/2 (E), and α7 nAChR (F) then determined by Western blotting. (G) After 24 h of transfection, the cells were treated with 10μM U0126 or MLA for 2 hr, and the level of the αAPP then determined by Western blotting. (H) SH-SY5Y/APPswe cells were treated with 50 μM RSV+ 10 μM U1026 or 300 μg/ml suramin+10 μM U1026, and the level of α7 nAChR expression then determined by Western blotting. The values presented are means ± SD. *P<0.05 and **P<0.01 compared to the negative control group, #P<0.05 compared to the group treated with U1026, as determined by analysis of variance (ANOVA), followed by the Tukey HSD test. Representative western blots are shown beneath A and C–H.