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. 2002 Sep 18;99(20):13254–13259. doi: 10.1073/pnas.202355799

Figure 1.

Figure 1

Effect of the Gq signaling pathway on TCF/LEF-1-mediated transcriptional activity and proliferation. (a) Effects of various Gα subunits on β-catenin-dependent TCF/LEF-1 transcriptional activity. SW480 cells were transfected with 025 μg of empty vector as control or cDNAs encoding various constitutively activated Gα subunits, and relative TCF/LEF-1 activity was measured. The results are expressed as mean ± SD of duplicates. (b) Activation of Gq-coupled receptor inhibits β-catenin-dependent TCF/LEF-1 transcriptional activity. SW480 cells were transfected with empty vector as control or cDNAs expressing WT or mutant activated Gαq, M2R, or M3R as indicated. Carbachol (1 mM) was added 24 h after transfection, and transcriptional activity was measured 48 h after transfection. (c) Q209L–Gαq down-regulates the cyclin D1 protein level. SW480 cells were transfected with empty plasmid pIRES2-EGFP as control or pQ209L-Gαq-IRES2-EGFP expression plasmid. EGFP-positive cells were enriched by fluorescence-activated cell sorting. Cell extracts were prepared, electrophoretically resolved, and immunoblotted with cyclin D1 antibody. β-actin was used for loading control. WB, Western blot. (d) Q209L–Gαq inhibits proliferation of SW480 cells. Cells were prepared as in c. Indicated number of cells was plated on 96-well plates and assayed for proliferation by using a colorimeteric assay. Cell proliferation was normalized with corresponding control cells transfected with empty vector and shown as mean ± SD.