Homer3 regulates the establishment of neutrophil polarity.
Homer3 regulates the establishment of neutrophil polarity.
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DOI：
10.1091/mbc.e14-07-1197
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发表时间：
2015-05-01
影响因子：
3.3
通讯作者：
Weiner OD
中科院分区：
文献类型：
--
作者：
Wu J;Pipathsouk A;Keizer-Gunnink A;Fusetti F;Alkema W;Liu S;Altschuler S;Wu L;Kortholt A;Weiner OD
大多数趋化因子依赖异源三聚体G蛋白Gαi的激活来调节细胞的定向迁移，但从Gαi到趋化效应物的联系却鲜为人知。Homer3是一种新型的与Gαi2相互作用的蛋白质，它在空间上组织肌动蛋白组装，以支持中性粒细胞有效的极性和运动性。
大多数趋化因子依赖异源三聚体G蛋白Gαi的激活来调节细胞的定向迁移，但从Gαi到趋化效应物的联系却鲜为人知。通过使用原代中性粒细胞裂解物进行亲和层析，我们将Homer3鉴定为一种新型的Gαi2结合蛋白。在类中性粒细胞HL - 60细胞中，RNA干扰介导的Homer3敲低会损害趋化性以及磷脂酰肌醇3,4,5 - 三磷酸（PIP3）和肌动蛋白细胞骨架极性的建立，以及WAVE2复合物的持续性。大多数先前已被鉴定为细胞极性所必需的蛋白质是肌动蛋白组装或核心趋化效应物（如Rac GTP酶）激活所需要的。相比之下，Homer3敲低的细胞显示出趋化因子诱导的磷酸肌醇3 - 激酶和Rac效应物激活的正常幅度和动力学。趋化因子刺激的Homer3敲低细胞也表现出肌动蛋白聚合的正常初始幅度，但无法使肌动蛋白组装和细胞内PIP3极化，并且在细胞极性和运动性的起始方面存在缺陷。我们的数据表明，Homer3作为一种支架，在空间上组织肌动蛋白组装，以支持G蛋白偶联受体激活下游的中性粒细胞极性和运动性。
Most chemoattractants rely on activation of the heterotrimeric G-protein Gαi to regulate directional cell migration, but few links from Gαi to chemotactic effectors are known. Homer3 is a novel Gαi2-interacting protein that spatially organizes actin assembly to support efficient polarity and motility in neutrophils. Most chemoattractants rely on activation of the heterotrimeric G-protein Gαi to regulate directional cell migration, but few links from Gαi to chemotactic effectors are known. Through affinity chromatography using primary neutrophil lysate, we identify Homer3 as a novel Gαi2-binding protein. RNA interference–mediated knockdown of Homer3 in neutrophil-like HL-60 cells impairs chemotaxis and the establishment of polarity of phosphatidylinositol 3,4,5-triphosphate (PIP3) and the actin cytoskeleton, as well as the persistence of the WAVE2 complex. Most previously characterized proteins that are required for cell polarity are needed for actin assembly or activation of core chemotactic effectors such as the Rac GTPase. In contrast, Homer3-knockdown cells show normal magnitude and kinetics of chemoattractant-induced activation of phosphoinositide 3-kinase and Rac effectors. Chemoattractant-stimulated Homer3-knockdown cells also exhibit a normal initial magnitude of actin polymerization but fail to polarize actin assembly and intracellular PIP3 and are defective in the initiation of cell polarity and motility. Our data suggest that Homer3 acts as a scaffold that spatially organizes actin assembly to support neutrophil polarity and motility downstream of GPCR activation.