Ezrin oligomers are major cytoskeletal components of placental microvilli: a proposal for their involvement in cortical morphogenesis.
Ezrin oligomers are major cytoskeletal components of placental microvilli: a proposal for their involvement in cortical morphogenesis.
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DOI：
10.1083/jcb.131.5.1231
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发表时间：
1995-12
期刊：
影响因子：
--
通讯作者：
Bretscher A
中科院分区：
文献类型：
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作者：
Berryman M;Gary R;Bretscher A
Ezrin是多种极化上皮细胞微绒毛细胞骨架的组成部分，被认为是膜-细胞骨架连接物。在这项研究中，我们从人胎盘合体滋养层细胞中分离出微绒毛，作为Ezrin功能的生化分析的模型系统。与肠道微绒毛相比，Ezrin是胎盘微绒毛的主要蛋白质组分，约占总蛋白质量的5%，约占肌动蛋白摩尔丰度的四分之一。凝胶过滤和化学交联研究表明，Ezrin主要以非共价二聚体和高阶低聚物的形式存在于胎盘微绒毛提取物中。一种新的形式的Ezrin，显然代表共价交联的加合物，作为胎盘微绒毛的相对次要的成分存在。寡聚体和加合物仍然与洗涤剂不溶的细胞骨架结合，表明与肌动蛋白细丝的紧密相互作用。此外，EGF对人A431癌细胞的刺激可以在体内诱导Ezrin寡聚体的快速形成，从而识别出一条与Ezrin寡聚和微绒毛组装相一致的信号转导途径。除了时间进程研究外，使用酪氨酸激酶和酪氨酸磷酸酶抑制剂的实验显示，Ezrin在酪氨酸上的磷酸化与低聚物形成的开始之间存在相关性，这与Ezrin可能需要磷酸化才能产生稳定的低聚物的可能性是一致的。在此基础上，提出了细胞表面结构组装的模型。
Ezrin is a component of the microvillus cytoskeleton of a variety of polarized epithelial cells and is believed to function as a membrane- cytoskeletal linker. In this study, we isolated microvilli from human placental syncytiotrophoblast as a model system for biochemical analysis of ezrin function. In contrast to intestinal microvilli, ezrin is a major protein component of placental microvilli, comprising approximately 5% of the total protein mass and present at about one quarter of the molar abundance of actin. Gel filtration and chemical cross-linking studies demonstrated that ezrin exists mainly in the form of noncovalent dimers and higher order oligomers in extracts of placental microvilli. A novel form of ezrin, apparently representing covalently cross-linked adducts, was present as a relatively minor constituent of placental microvilli. Both oligomers and adducts remained associated with the detergent-insoluble cytoskeleton, indicating a tight interaction with actin filaments. Moreover, stimulation of human A431 carcinoma cells with EGF induces the rapid formation of ezrin oligomers in vivo, thus identifying a signal transduction pathway involving ezrin oligomerization coincident with microvillus assembly. In addition to time course studies, experiments with tyrosine kinase and tyrosine phosphatase inhibitors revealed a correlation between the phosphorylation of ezrin on tyrosine and the onset of oligomer formation, consistent with the possibility that phosphorylation of ezrin might be required for the generation of stable oligomers. Based on these observations, a model for the assembly of cell surface structures is proposed.