Wnt5a-Ror signaling is a conserved pathway that regulates morphogenetic processes during vertebrate development [R. T. Moon et al., Development 119, 97–111 (1993); I. Oishi et al., Genes Cells 8, 645–654 (2003)], but its downstream signaling events remain poorly understood. Through a large-scale proteomic screen in mouse embryonic fibroblasts, we identified the E3 ubiquitin ligase Pdzrn3 as a regulatory target of the Wnt5a-Ror pathway. Upon pathway activation, Pdzrn3 is degraded in a β-catenin–independent, ubiquitin-proteasome system–dependent manner. We developed a flow cytometry-based reporter to monitor Pdzrn3 abundance and delineated a signaling cascade involving Frizzled, Dishevelled, Casein kinase 1, and Glycogen synthase kinase 3 that regulates Pdzrn3 stability. Epistatically, Pdzrn3 is regulated independently of Kif26b, another Wnt5a-Ror effector. Wnt5a-dependent degradation of Pdzrn3 requires phosphorylation of three conserved amino acids within its C-terminal LNX3H domain [M. Flynn, O. Saha, P. Young, BMC Evol. Biol. 11, 235 (2011)], which acts as a bona fide Wnt5a-responsive element. Importantly, this phospho-dependent degradation is essential for Wnt5a-Ror modulation of cell migration. Collectively, this work establishes a Wnt5a-Ror cell morphogenetic cascade involving Pdzrn3 phosphorylation and degradation.

Wnt5a-Ror 信号传导是在脊椎动物发育过程中调节形态发生过程的保守途径 [RT Moon等人，Development 119, 97-111 (1993)；I. Oishi等人，基因细胞8, 645–654 (2003)]，但其下游信号事件仍然知之甚少。通过对小鼠胚胎成纤维细胞的大规模蛋白质组学筛选，我们将 E3 泛素连接酶 Pdzrn3 鉴定为 Wnt5a-Ror 通路的调节靶点。在通路激活后，Pdzrn3 以不依赖 β-连环蛋白、依赖泛素-蛋白酶体系统的方式降解。我们开发了一种基于流式细胞术的报告器来监测 Pdzrn3 的丰度，并描绘了一个涉及 Frizzled、Dishevelled、酪蛋白激酶 1 和调节 Pdzrn3 稳定性的糖原合酶激酶 3 的信号级联。在上位性上，Pdzrn3 独立于 Kif26b（另一种 Wnt5a-Ror 效应器）进行调节。Pdzrn3 的 Wnt5a 依赖性降解需要磷酸化其 C 端 LNX3H 结构域内的三个保守氨基酸 [M. 弗林，O. Saha，P. Young，BMC进化版。生物学。11, 235 (2011)]，它作为真正的 Wnt5a 响应元件。重要的是，这种磷酸依赖性降解对于 Wnt5a-Ror 调节细胞迁移至关重要。总的来说，这项工作建立了一个涉及 Pdzrn3 磷酸化和降解的 Wnt5a-Ror 细胞形态发生级联。