Figure 9.

${\text{siI}}_2^{\text{PP2A}}$ attenuates tau hyperphosphorylation induced by okadaic acid in HEK293/tau or N2a/tau cells. ${\text{pSUP - siI}}_2^{\text{PP2A}}$ (pSUP-siI₂) was transfected into HEK293/tau (A–C) or N2a/tau cells (D) to knockdown the expression of ${\text{I}}_2^{\text{PP2A}}$, and pSUP and pSUP-siC were expressed as the controls. After 24 h, OA (okadaic acid, 25 nM) was administered for 24 h. (A,B) The relative levels of hyperphosphorylated tau at Ser-199 (pS199), Ser-198/202 (tau-1), Thr-205 (pT205), Ser-214 (pS214), Thr-231 (pT231), Ser-396 (pS396), and Ser-404 (pS404) epitopes were detected by Western blotting (A) and quantitative analysis (B). (C) The phosphorylated levels of tau at Ser-198/202 (tau-1), Ser-396, and Ser-404 epitopes were detected by immunofluorescence staining. (D) The relative levels of hyperphosphorylation tau at Ser-198/202 (tau-1) and Ser-396 (pS396) epitopes were detected by Western blotting and quantitative analysis. The relative intensity was normalized against total tau probed by R134d or tau-5 and expressed by setting pSUP as 1. DM1A serves as a loading control. The data were presented as mean ± SD of at least three independent experiments. *p < 0.05; **p < 0.01 vs. pSUP; ^#p < 0.05; ^##p < 0.01 vs. pSUP + OA.