6jck | pdb_00006jck
Complex structure of Axin-DIX and Dvl2-DIX
Structural highlights
DiseaseAXIN1_HUMAN Defects in AXIN1 are involved in hepatocellular carcinoma (HCC) [MIM:114550.[1] [2] Defects in AXIN1 are a cause of caudal duplication anomaly (CADUA) [MIM:607864. Caudal duplication anomaly is characterized by the occurrence of duplications of different organs in the caudal region. Note=Caudal duplication anomaly is associated with hypermethylation of the AXIN1 promoter.[3] FunctionAXIN1_HUMAN Component of the beta-catenin destruction complex required for regulating CTNNB1 levels through phosphorylation and ubiquitination, and modulating Wnt-signaling. Controls dorsoventral patterning via two opposing effects; down-regulates CTNNB1 to inhibit the Wnt signaling pathway and ventralize embryos, but also dorsalizes embryos by activating a Wnt-independent JNK signaling pathway. In Wnt signaling, probably facilitates the phosphorylation of CTNNB1 and APC by GSK3B. Likely to function as a tumor suppressor. Facilitates the phosphorylation of TP53 by HIPK2 upon ultraviolet irradiation. Enhances TGF-beta signaling by recruiting the RNF111 E3 ubiquitin ligase and promoting the degradation of inhibitory SMAD7. Also component of the AXIN1-HIPK2-TP53 complex which controls cell growth, apoptosis and development.[4] [5] [6] Publication Abstract from PubMedThe Wnt-beta-catenin signaling pathway regulates embryonic development and tissue homeostasis throughout the animal kingdom. Signaling through this pathway crucially depends on the opposing activities of two cytoplasmic multiprotein complexes: the Axin destruction complex, which destabilizes the downstream effector beta-catenin, and the Dishevelled signalosome, which inactivates the Axin complex and thus enables beta-catenin to accumulate and operate a transcriptional switch in the nucleus. These complexes are assembled by dynamic head-to-tail polymerization of the DIX domains of Axin or Dishevelled, respectively, which increases their avidity for signaling effectors. Axin also binds to Dishevelled through its DIX domain. Here, we report the crystal structure of the heterodimeric complex between the two DIX domains of Axin and Dishevelled. This heterotypic interface resembles the interfaces observed in the individual homopolymers, albeit exhibiting a slight rearrangement of electrostatic interactions and hydrogen bonds, consistent with the heterotypic interaction being favored over the homotypic Axin DIX interaction. Last, cell-based signaling assays showed that heterologous polymerizing domains functionally substituted for the DIX domain of Dishevelled provided that these Dishevelled chimeras retained a DIX head or tail surface capable of binding to Axin. These findings indicate that the interaction between Dishevelled and Axin through their DIX domains is crucial for signaling to beta-catenin. A direct heterotypic interaction between the DIX domains of Dishevelled and Axin mediates signaling to beta-catenin.,Yamanishi K, Fiedler M, Terawaki SI, Higuchi Y, Bienz M, Shibata N Sci Signal. 2019 Dec 10;12(611):eaaw5505. doi: 10.1126/scisignal.aaw5505. PMID:31822591[7] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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