Division of Developmental Biology, Institute of Biodynamics and Biocomplexity, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands.
Univ Rennes, CNRS, IGDR (Institut de Génétique et de Développement de Rennes), UMR 6290, F-35000 Rennes, France.
Development. 2020 Jul 22;147(14):dev188011. doi: 10.1242/dev.188011.
ERM proteins are conserved regulators of cortical membrane specialization that function as membrane-actin linkers and molecular hubs. The activity of ERM proteins requires a conformational switch from an inactive cytoplasmic form into an active membrane- and actin-bound form, which is thought to be mediated by sequential PIP binding and phosphorylation of a conserved C-terminal threonine residue. Here, we use the single ERM ortholog, ERM-1, to study the contribution of these regulatory events to ERM activity and tissue formation Using CRISPR/Cas9-generated mutant alleles, we demonstrate that a PIP-binding site is crucially required for ERM-1 function. By contrast, dynamic regulation of C-terminal T544 phosphorylation is not essential but modulates ERM-1 apical localization and dynamics in a tissue-specific manner, to control cortical actin organization and support lumen formation in epithelial tubes. Our work highlights the dynamic nature of ERM protein regulation during tissue morphogenesis and the importance of C-terminal phosphorylation in fine-tuning ERM activity in a tissue-specific context.
ERM 蛋白是皮质膜特化的保守调节因子，作为膜肌动蛋白连接子和分子枢纽发挥作用。ERM 蛋白的活性需要从非活性的细胞质形式转换为活性的膜和肌动蛋白结合形式，这被认为是通过顺序 PIP 结合和保守 C 末端苏氨酸残基的磷酸化介导的。在这里，我们使用单一的 ERM 直系同源物 ERM-1 来研究这些调节事件对 ERM 活性和组织形成的贡献。使用 CRISPR/Cas9 产生的突变等位基因，我们证明 PIP 结合位点对 ERM-1 功能至关重要。相比之下，C 末端 T544 磷酸化的动态调节不是必需的，但以组织特异性的方式调节 ERM-1 的顶端定位和动力学，以控制皮质肌动蛋白组织和支持上皮管腔的形成。我们的工作强调了 ERM 蛋白在组织形态发生过程中的动态调节性质，以及 C 末端磷酸化在特定组织环境中精细调节 ERM 活性的重要性。
