beta-catenin

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beta-catenin

A cell–cell adhesion protein that binds to the cytoplasmic domain of E-cadherin. The beta-catenin-cadherin complex recruits alpha-catenin, which in turn binds actin of the cytoskeleton, together forming intercellular adherens junction. Beta-catenin also acts as a component of the Wnt signal transduction pathway, which regulates cell proliferation and differentiation. Tissue concentrations of free beta-catenin are controlled by a protein complex (adenomatous polyposis coli protein and glycogen synthetase kinase3a) which facilitates its breakdown. Wnt inactivates glycogen synthetase kinase3b, allowing beta-catenin to accumulate in cytoplasm and in the nucleus, where it activates the TCF/LEF transcription factors, which in turn act on c-myc, tcf-1 and cyclin D1.

Normal expression
Normal cells show membrane staining for beta-catenin. Beta-catenin expression is regulated by the adenomatous polyposis coli (APC) gene.
 
Abnormal expression
Cytoplasmic and/or nuclear staining is abnormal. Mutant CTNNB1 can lead to stabilisation of beta-catenin in the cytoplasm and translocation to the nucleus; disregulation of beta-catenin occurs in Gardner syndrome, leading to familial adenomatous polyposis and fibromatosis. Beta-catenin expression is increased in aggressive fibromatosis, synovial sarcoma, osteosarcoma, liposarcoma and malignant fibrous histiocytoma. High nuclear expression is seen in some mesenchymal tumours; cytoplasmic staining is seen in many. In contrast, cytoplasmic accumulation of beta-catenin is a generally good prognostic marker in upper and lower GI adenocarcinomas.
References in periodicals archive ?
SPN shows strong nuclear and cytoplasmic beta catenin immunoreactivity in 100% cases and loss of membrane staining for E-cadherin (due to activation of the Wnt signaling pathway).
Omega-3 fatty acids present in fish appear to reduce the levels of beta catenin. Elevated levels of beta catenin are associated with the development of variety of tumours.
The present paper focuses on chemo prevention with phytochemicals [15,19] at the same time avoiding of beta catenin from diet [18] which is associated with the development of tumours which may ultimately turn to be malignant [3].
Timing a lithium-induced rise in beta catenin with the arrival of these cells may optimize healing, he says.--N.S.
Medical experts claim the miracle chemical beta catenin could be used to "reprogramme" hairless adult skin to grow new folicles.