Mbele Gaelh Ouengue, Deloulme Jean Christophe, Gentil Benoît Jean, Delphin Christian, Ferro Myriam, Garin Jérôme, Takahashi Miyoko, Baudier Jacques
Département Réponse et Différenciation Cellulaires du Commissariat à l'Energie Atomique (CEA), INSERM EMI-0104 DRDC-TS, Grenoble 38054, France.
J Biol Chem. 2002 Dec 20;277(51):49998-50007. doi: 10.1074/jbc.M205363200. Epub 2002 Oct 10.
The Zn(2+)- and Ca(2+)-binding S100B protein is implicated in multiple intracellular and extracellular regulatory events. In glial cells, a relationship exists between cytoplasmic S100B accumulation and cell morphological changes. We have identified the IQGAP1 protein as the major cytoplasmic S100B target protein in different rat and human glial cell lines in the presence of Zn(2+) and Ca(2+). Zn(2+) binding to S100B is sufficient to promote interaction with IQGAP1. IQ motifs on IQGAP1 represent the minimal interaction sites for S100B. We also provide evidence that, in human astrocytoma cell lines, S100B co-localizes with IQGAP1 at the polarized leading edge and areas of membrane ruffling and that both proteins relocate in a Ca(2+)-dependent manner within newly formed vesicle-like structures. Our data identify IQGAP1 as a potential target protein of S100B during processes of dynamic rearrangement of cell membrane morphology. They also reveal an additional cellular function for IQGAP1 associated with Zn(2+)/Ca(2+)-dependent relocation of S100B.
锌离子（Zn²⁺）和钙离子（Ca²⁺）结合的S100B蛋白参与多种细胞内和细胞外调节事件。在神经胶质细胞中，细胞质S100B的积累与细胞形态变化之间存在关联。我们已确定IQGAP1蛋白是在锌离子（Zn²⁺）和钙离子（Ca²⁺）存在的情况下，不同大鼠和人类神经胶质细胞系中主要的细胞质S100B靶蛋白。锌离子（Zn²⁺）与S100B的结合足以促进其与IQGAP1的相互作用。IQGAP1上的IQ基序代表了与S100B相互作用的最小位点。我们还提供了证据表明，在人类星形细胞瘤细胞系中，S100B与IQGAP1在极化的前沿和膜皱襞区域共定位，并且这两种蛋白在新形成的囊泡状结构内以钙离子（Ca²⁺）依赖的方式重新定位。我们的数据确定IQGAP1是细胞膜形态动态重排过程中S100B的潜在靶蛋白。它们还揭示了与S100B的锌离子（Zn²⁺）/钙离子（Ca²⁺）依赖的重新定位相关的IQGAP1的另一种细胞功能。
