Figure 1

Suppression of PP2A potentiates the Wnt/β-catenin signaling. Panel A, OA enhanced the Lef/Tcf-sensitive transcription activity in response to Wnt3a. F9 cells expressing Rfz1 were treated with Wnt3a for 8 hr in the absence or presence of OA, added 60 min prior to stimulation with Wnt3a. Cells were lysed and the Lef/Tcf-sensitive gene transcription was assayed in samples of cell lysates using the M50 luciferase gene reporter. The results showed mean values ± S.E. that were obtained from five separate experiments. Statistical significance is noted (*, p < 0.001; **, p < 0.05). Panel B, OA enhanced the time-course of activation of Lef/Tcf-sensitive transcription in response to stimulation by Wnt3a. F9 cells expressing Rfz1 were treated without (open circle) or with (closed circle) OA and Wnt3a added for a 10 hr stimulation. Cells were harvested at indicated time points and disrupted. The Lef/Tcf-sensitive gene transcription was assayed. The results shown are mean values ± S.E. obtained from four separate experiments. Statistical significance is denoted (*, for p < 0.005). Panel C, effects of OA on the cellular abundance of Wnt/β-catenin signaling elements in response to long-term (0–10 hr) stimulation by Wnt3a. The cellular content of β-catenin, Dvl2, GSK3β, and GAPDH (as a control) were established in F9 cells expressing Rfz1 and stimulated with Wnt3a, in the absence or presence of OA, for 0–10 hr. The results shown are mean values ± S.E. obtained from four separate experiments. Representative blots are displayed.