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 ?
The specific aims of this study are to (1) test whether the sponge homologs of Wnt/beta-catenin components interact (2) identify the tissue-specific and subcellular localization patterns of beta-catenin and TCF (these proteins form the transcriptional complex downstream of the Wnt/beta-catenin pathway) (3) identify which target genes are regulated by the beta-catenin/TCF transcriptional complex and (4) develop techniques for studying gene function in vivo in sponges.
University of North Carolina, Chapel Hill "Role of LINC Complex in Maintenance of MSC Beta-Catenin Signaling Under Microgravity" Mentor: Janet Rubin, M.
Activation of c-Myc and cyclin Dl by JCV T-antigen and beta-catenin in colon cancer.
Molecularly, type 1 tumors often exhibit mutations in phosphatase and tensin homolog (PTEN), Kras, and beta-catenin.
This protein, known as beta-catenin, which is normally found in intestinal epithelial cells where it facilitates their cohesion, builds up in large quantities in other areas of the cells when the tumour transformation begins.
and was shown to inhibit the Stat3 pathways, Nanog pathways and beta-catenin pathways in pre-clinical study.
A second study by the same group of researchers suggests that cosmic radiation prevents gut cells from destroying a protein called beta-catenin, which in turn, promotes uncontrolled cell growth.
20) Beta-catenin mutations that play a key role in liver development, regeneration and oncogenesis, are found in 50-90% of HB tumours.
This work builds on ours and [that of] other groups, and shows that it's possible to block the cancer-promoting interaction between BCL9 and beta-catenin, two key proteins in the Wnt signalling pathway," said Dr Mariann Bienz, a scientist from the MRC Laboratory of Molecular Biology in Cambridge, England.
Beta-catenin acts as a Wnt signaling mediator to induce gene expression which results in the regulation of cell proliferation and differentiation.