CRYSTAL STRUCTURE OF THE XTCF3-CBD/BETA-CATENIN ARMADILLO REPEAT COMPLEX
[CTNB1_HUMAN] Defects in CTNNB1 are associated with colorectal cancer (CRC) [MIM:114500]. Note=Activating mutations in CTNNB1 have oncogenic activity resulting in tumor development. Somatic mutations are found in various tumor types, including colon cancers, ovarian and prostate carcinomas, hepatoblastoma (HB), hepatocellular carcinoma (HCC). HBs are malignant embryonal tumors mainly affecting young children in the first three years of life. Defects in CTNNB1 are a cause of pilomatrixoma (PTR) [MIM:132600]; a common benign skin tumor.   Defects in CTNNB1 are a cause of medulloblastoma (MDB) [MIM:155255]. MDB is a malignant, invasive embryonal tumor of the cerebellum with a preferential manifestation in children.  Defects in CTNNB1 are a cause of susceptibility to ovarian cancer (OC) [MIM:167000]. Ovarian cancer common malignancy originating from ovarian tissue. Although many histologic types of ovarian neoplasms have been described, epithelial ovarian carcinoma is the most common form. Ovarian cancers are often asymptomatic and the recognized signs and symptoms, even of late-stage disease, are vague. Consequently, most patients are diagnosed with advanced disease. Note=A chromosomal aberration involving CTNNB1 is found in salivary gland pleiomorphic adenomas, the most common benign epithelial tumors of the salivary gland. Translocation t(3;8)(p21;q12) with PLAG1. Defects in CTNNB1 may be a cause of mesothelioma malignant (MESOM) [MIM:156240]. An aggressive neoplasm of the serosal lining of the chest. It appears as broad sheets of cells, with some regions containing spindle-shaped, sarcoma-like cells and other regions showing adenomatous patterns. Pleural mesotheliomas have been linked to exposure to asbestos.
[CTNB1_HUMAN] Key downstream component of the canonical Wnt signaling pathway. In the absence of Wnt, forms a complex with AXIN1, AXIN2, APC, CSNK1A1 and GSK3B that promotes phosphorylation on N-terminal Ser and Thr residues and ubiquitination of CTNNB1 via BTRC and its subsequent degradation by the proteasome. In the presence of Wnt ligand, CTNNB1 is not ubiquitinated and accumulates in the nucleus, where it acts as a coactivator for transcription factors of the TCF/LEF family, leading to activate Wnt responsive genes. Involved in the regulation of cell adhesion. Acts as a negative regulator of centrosome cohesion. Involved in the CDK2/PTPN6/CTNNB1/CEACAM1 pathway of insulin internalization. Blocks anoikis of malignant kidney and intestinal epithelial cells and promotes their anchorage-independent growth by down-regulating DAPK2.    [T7L1A_XENLA] Participates in the Wnt signaling pathway. Binds to DNA and acts as a repressor in the absence of ctnnb1-A and possibly ctnnb1-B, and as an activator in the presence of these proteins. Required early in development for the establishment of the dorsal body axis in response to maternal Wnt signaling. Also required during development of the CNS for the establishment of dorsal-ventral patterning in the prospective diencephalon.                
Publication Abstract from PubMed
The Wnt signaling pathway plays critical roles in embryonic development and tumorigenesis. Stimulation of the Wnt pathway results in the accumulation of a nuclear beta-catenin/Tcf complex, activating Wnt target genes. A crystal structure of beta-catenin bound to the beta-catenin binding domain of Tcf3 (Tcf3-CBD) has been determined. The Tcf3-CBD forms an elongated structure with three binding modules that runs antiparallel to beta-catenin along the positively charged groove formed by the armadillo repeats. Structure-based mutagenesis defines three sites in beta-catenin that are critical for binding the Tcf3-CBD and are differentially involved in binding APC, cadherin, and Axin. The structural and mutagenesis data reveal a potential target for molecular drug design studies.
Crystal structure of a beta-catenin/Tcf complex.,Graham TA, Weaver C, Mao F, Kimelman D, Xu W Cell. 2000 Dec 8;103(6):885-96. PMID:11136974
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.