Identification of the Axin and Frat binding region of glycogen synthase kinase-3
Identification of the Axin and Frat binding region of glycogen synthase kinase-3
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DOI：
10.1074/jbc.m109462200
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发表时间：
2002-01-18
影响因子：
4.8
通讯作者：
Dale, TC
中科院分区：
文献类型：
--
作者：
Fraser, E;Young, N;Dale, TC
糖原合成酶激酶-3（GSK-3）是包括Wnt和胰岛素配体调节的信号通路在内的多种信号通路的关键组分。GSK-3信号传导的特异性被认为涉及与定位GSK-3调节剂和底物的支架蛋白的相互作用。该报告显示GSK-3形成低亲和力同源二聚体，其通过与Axin和Frat结合而被破坏。基于GSK-3的晶体结构，我们使用表面扫描诱变来鉴定差异影响GSK-3相互作用的残基。在二聚体界面破坏Frat和Axin簇的突变解释了它们对同源二聚体形成的影响。Axin结合位点的缺失阻断了显性阴性GSK-3引起爪蟾胚胎中轴复制的能力。Axin结合位点在所有GSK-3蛋白中都是保守的，它的丢失影响非后生动物网骨藻中的细胞运动性和基因表达。令人惊讶的是，我们发现非Axin结合GSK-3突变体和T细胞因子活性之间没有遗传相互作用，认为Axin相互作用本身不能解释T细胞因子介导的基因表达调控。
Glycogen synthase kinase-3 (GSK-3) is a key component of several signaling pathways including those regulated by Wnt and insulin ligands. Specificity in GSK-3 signaling is thought to involve interactions with scaffold proteins that localize GSK-3 regulators and substrates. This report shows that GSK-3 forms a low affinity homodimer that is disrupted by binding to Axin and Frat. Based on the crystal structure of GSK-3, we have used surface-scanning mutagenesis to identify residues that differentially affect GSK-3 interactions. Mutations that disrupt Frat and Axin cluster at the dimer interface explaining their effect on homodimer formation. Loss of the Axin binding site blocks the ability of dominant negative GSK-3 to cause axis duplication in Xenopus embryos. The Axin binding site is conserved within all GSK-3 proteins, and its loss affects both cell motility and gene expression in the nonmetazoan, Dictyostelium. Surprisingly, we find no genetic interaction between a non-Axin-binding GSK-3 mutant and T-cell factor activity, arguing that Axin interactions alone cannot explain the regulation of T-cell factor-mediated gene expression.