Betacatenine

Betacatenine, commonly called beta-catenin (β-catenin), is a protein encoded by the CTNNB1 gene in humans. It has dual roles in cell–cell adhesion and Wnt signaling, making it a central component of both tissue architecture and transcriptional regulation.

In adherens junctions, beta-catenin binds cadherins through its armadillo repeats and interacts with alpha-catenin to connect the junction to the actin cytoskeleton, helping to maintain epithelial integrity.

In the canonical Wnt pathway, beta-catenin acts as a transcriptional co-activator. In the absence of Wnt, it is phosphorylated by a destruction complex (APC, Axin, GSK-3β, CK1) and targeted for proteasomal degradation. When Wnt signals are present, the destruction complex is inhibited, stabilizing beta-catenin, which accumulates in the cytoplasm and translocates to the nucleus to partner with TCF/LEF transcription factors and activate target genes involved in cell proliferation and differentiation.

Dysregulation of beta-catenin signaling, via CTNNB1 mutations or loss of APC, can lead to constitutive pathway activation and contributes to tumorigenesis, particularly in colorectal cancer, but also in hepatocellular, endometrial, and other tumors.

Beta-catenin is regulated by post-translational modifications and interacts with multiple signaling pathways, with isoforms and splice variants adding to functional complexity. It remains a focus of cancer research and developmental biology due to its central role in cell fate decisions and tissue homeostasis.