The Nina Ireland Laboratory of Developmental Neurobiology, Department of Psychiatry, University of California San Francisco, 1550 4th St, San Francisco CA 94158-2324, USA.
BMC Biochem. 2011 Jun 30;12:33. doi: 10.1186/1471-2091-12-33.
The Dact family of scaffold proteins was discovered by virtue of binding to Dvl proteins central to Wnt and Planar Cell Polarity (PCP) signaling. Subsequently Dact proteins have been linked to a growing list of potential partners implicated in β-catenin-dependent and β-catenin-independent forms of Wnt and other signaling. To clarify conserved and non-conserved roles for this protein family, we systematically compared molecular interactions of all three murine Dact paralogs by co-immunoprecipitation of proteins recombinantly expressed in cultured human embryonic kidney cells.
Every Dact paralog readily formed complexes with the Vangl, Dvl, and CK1δ/ε proteins of species ranging from fruit flies to humans, as well as with PKA and PKC. Dact proteins also formed complexes with themselves and with each other; their conserved N-terminal leucine-zipper domains, which have no known binding partners, were necessary and sufficient for this interaction, suggesting that it reflects leucine-zipper-mediated homo- and hetero-dimerization. We also found weaker, though conserved, interactions of all three Dact paralogs with the catenin superfamily member p120ctn. Complex formation with other previously proposed partners including most other catenins, GSK3, LEF/TCF, HDAC1, and TGFβ receptors was paralog-specific, comparatively weak, and/or more sensitive to empirical conditions.
Combined with published functional evidence from targeted knock-out mice, these data support a conserved role for Dact proteins in kinase-regulated biochemistry involving Vangl and Dvl. This strongly suggests that a principal role for all Dact family members is in the PCP pathway or a molecularly related signaling cascade in vertebrates.
支架蛋白 Dact 家族是通过与 Wnt 和平面细胞极性（PCP）信号通路中的 Dvl 蛋白结合而发现的。随后，Dact 蛋白与越来越多的潜在伴侣相关联，这些伴侣参与 β-连环蛋白依赖性和非依赖性 Wnt 和其他信号通路。为了阐明该蛋白家族的保守和非保守作用，我们通过在培养的人胚肾细胞中重组表达蛋白质的共免疫沉淀，系统地比较了所有三种鼠类 Dact 同源物的分子相互作用。
每个 Dact 同源物都与从果蝇到人类的 Vangl、Dvl 和 CK1δ/ε 蛋白以及 PKA 和 PKC 形成复合物。Dact 蛋白也与自身和彼此形成复合物；它们保守的 N 端亮氨酸拉链结构域没有已知的结合伙伴，对于这种相互作用是必需的和充分的，这表明它反映了亮氨酸拉链介导的同源和异源二聚化。我们还发现，所有三种 Dact 同源物与连接蛋白超家族成员 p120ctn 之间存在较弱但保守的相互作用。与其他先前提出的包括大多数其他连接蛋白、GSK3、LEF/TCF、HDAC1 和 TGFβ 受体的合作伙伴形成复合物是同种型特异性的、相对较弱的和/或对经验条件更敏感。
结合靶向敲除小鼠的已发表功能证据，这些数据支持 Dact 蛋白在涉及 Vangl 和 Dvl 的激酶调节生物化学中发挥保守作用。这强烈表明所有 Dact 家族成员的主要作用是在 PCP 途径或脊椎动物中分子相关的信号级联中。
