Phosphorylation-independent membrane relocalization of ezrin following association with Dbl in vivo
Phosphorylation-independent membrane relocalization of ezrin following association with Dbl in vivo
复制标题
体内与 Dbl 结合后埃兹蛋白的磷酸化依赖性膜重新定位
作者：
C. Vanni;A. Parodi;P. Mancini;V. Visco;C. Ottaviano;M. Torrisi;A. Eva
Ezrin是一种广泛存在的参与细胞迁移、形态发生和细胞粘附的蛋白质，属于称为ERM的蛋白质大家族（ezrin、radixin、moesin）。这三种密切相关的蛋白质被认为是质膜和肌动蛋白细胞骨架之间的连接物，它们的功能受到小GTP结合蛋白Rho的调节。先前已经表明，活性形式的根蛋白可以在体外结合Dbl，Rho特异性鸟嘌呤核苷酸交换因子，虽然在体内的相互作用尚未得到证实。在本文中，我们试图调查是否ezrin也可以与Dbl。我们在这里表明，Dbl蛋白可以有效地结合在体外和体内的N-末端区域（氨基酸1 - 531）的ezrin的组成型活性突变体和全长分子。我们发现，这种结合是介导的Dbl pleckstrin同源结构域，负责适当的亚细胞定位的Dbl蛋白。此外，我们表明，Dbl诱导定位到质膜的活性缺失突变体和全长ezrin蛋白。最后，我们表明，ezrin的重新定位是独立的Dbl GEF活动。这些结果表明，Dbl可以通过一种不需要通过Rho相关激酶将ezrin C-末端磷酸化的机制诱导ezrin易位至质膜。
Ezrin, a widespread protein involved in cell migration, morphogenesis and cell adhesion, belongs to a large family of proteins known as ERM (ezrin, radixin, moesin). These three closely related proteins are thought to function as linkers between plasma membrane and actin cytoskeleton and their function is regulated by the small GTP-binding protein Rho. It has been previously shown that the active form of radixin can bind in vitro to Dbl, a Rho-specific guanine nucleotide exchange factor, although an in vivo interaction has not yet been demonstrated. In this paper, we attempted to investigate whether ezrin can also associate with Dbl. We show here that Dbl protein can effectively bind both in vitro and in vivo to the N-terminal region (amino acids 1–531) of a constitutively active mutant of ezrin and with the full-length molecule. We found that this binding is mediated by the Dbl pleckstrin homology domain, responsible for the proper subcellular localization of the Dbl protein. Moreover, we show that Dbl induces localization to the plasma membrane of both the active deletion mutant and the full-length ezrin proteins. Finally, we show that the relocalization of ezrin is independent of Dbl GEF activity. These results indicate that Dbl could induce translocation of ezrin to the plasma membrane through a mechanism that does not require ezrin C-terminus phosphorylation by Rho-associated kinases.