PKA activation enhances basal and stimulated Wnt/β-catenin -dependent transcriptional activity in MC3T3-E1 cells.

<p>A. Cells were transfected with a Wnt/β-catenin -reporter plasmid (TOPFlash) or the same plasmid with a mutation in the Wnt-responsive elements (FOPFlash). Luciferase assay was performed following treatment with vehicle, FSK, or Wnt3a (100 ng/ml) as indicated (* P<0.05, ** P<0.01). B. Luciferase assay was performed in cells with control or <i>Prkar1a</i> knockdown to measure the Wnt/β-catenin-reporter activity (** P<0.01). C. mRNA expression of Wnt/β-catenin target genes was determined using QPCR analysis. The expression of each was normalized to GAPDH expression (** P<0.01 versus DMSO treated cells). (D) Cells were transfected with TOPFlash or FOPFlash along with FLAG-tagged β-catenin or its PKA phosphorylation mutants, as indicated. The Wnt/β-catenin -reporter activity was measured by luciferase assay following stimulation of cells with forskolin. (** P<0.01 versus WT or single mutants, ∧ P<0.05 versus DMSO treated counterparts).