Proanthocyanidins Modulate β-Catenin Signaling

The purified fraction of proanthocyanidins from grape seeds were obtained from the Kikkoman Corp. (Noda, Japan). The β-catenin^S33Y pcDNA plasmid bearing FLAG tag used for the overexpression of non-degradable, constitutively active mutant form of β-catenin was obtained from Addgene (Cambridge, MA, USA), while β-catenin siRNA kit for knocking down the expression level of β-catenin along with the siRNA transfection reagents, and antibodies specific to PCNA, cyclin D1, cyclin D2, Cdks (2 (link),4 (link),6 (link)), Cip1/p21, Kip1/p27, β-catenin, β-actin, histone H3, horseradish peroxidase conjugated rabbit anti-goat and goat anti-rabbit secondary antibodies were purchased from Santa Cruz Biotechnology (Santa Cruz, CA, USA). The antibodies specific for Bax, Bcl-2, Bcl-xl, cleaved caspase-3, caspase-9, PARP, casein kinase 1α (CK1α), glycogen synthase kinase-3β (GSK-3β), and phospho forms of β-catenin were obtained from Cell Signaling Technology (Beverly, MA, USA). Annexin V-conjugated Alexa Fluor 488 apoptosis detection kit was purchased from Molecular Probes, Inc. (Eugene, OR, USA).