Research Paper Volume 11, Issue 21 pp 9672—9688

Glycogen synthase kinase-3β suppresses the expression of protein phosphatase methylesterase-1 through β-catenin

Figure 6. PI3K/AKT signaling upregulates the PME-1 expression through GSK-3β/β-catenin. (AC) HEK-293T cells were transfected with β-catenin and cultured without Fetal bovine serum (FBS, as control, con) or with 2% FBS for 48 hr. The cell lysates were analyzed for total GSK-3β, β-catenin, PME-1 and the phosphorylation of β-catenin and GSK-3β by Western blots (A). Levels of phosphorylated β-catenin and GSK-3β were normalized with corresponding proteins (B). The mRNA level of PME-1 was measured by qPCR and normalized with GAPDH (C). The protein level of PME-1 was quantified from panel A and normalized with GAPDH. (D) SH-SY5Y cells were treated with 100 nM insulin for 0.5 hr or 18 hr and analyzed by Western blots developed with indicated antibodies. (E, F) Primary cortical neurons were treated with 100 nM insulin for 18 hr. The levels of β-catenin and PME-1 were analyzed by Western blots (E) and normalized with GAPDH (F). (G) Primary cortical neurons were cultured and treated with the indicated concentration LY294002 for 4.5 hr. The PME-1 mRNA level was measured by qPCR and normalized with GAPDH. Data are presented as mean ± SD (n=3); *P < 0.05; **P < 0.01.