Gadkin negatively regulates cell spreading and motility via sequestration of the actin-nucleating ARP2/3 complex
Gadkin negatively regulates cell spreading and motility via sequestration of the actin-nucleating ARP2/3 complex
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DOI：
10.1073/pnas.1206468109
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发表时间：
2012-06-26
影响因子：
11.1
通讯作者：
Haucke, Volker
中科院分区：
文献类型：
--
作者：
Maritzen, Tanja;Zech, Tobias;Haucke, Volker
肌动蛋白动力学的调节是许多细胞生理过程的关键，从细胞突起的形成和细胞形状的控制到细胞运动、内吞作用和囊泡运动。肌动蛋白相关蛋白（ARP）2/3复合体是一个主要的肌动蛋白成核子，在板足突和促核因子（NPFs）下游的细胞迁移过程中组织支丝网络。尽管许多npf已被详细表征，但已知的ARP2/3抑制剂很少。在这里，我们确定了反式高尔基网络(TGN)/内体定位适配器蛋白(AP)-1相关适配器蛋白Gadkin作为ARP2/3功能的负调节因子。Gadkin缺失与ARP2/3向质膜的部分再分布以及细胞扩散和迁移增加有关，这些表型依赖于功能性ARP2/3复合物的存在。Gadkin通过保守的色氨酸酸性簇基序直接与ARP2/3结合，类似于npf的ARP2/3结合序列，但不能促进ARP2/3介导的肌动蛋白组装。与Gadkin对ARP2/3功能的抑制作用一致，在迁移抑制条件下，在NPFs激活后，在运动的含Gadkin的内体囊泡中发现了ARP2/3，从那里重新定位到质膜。再加上Gadkin介导的细胞扩散抑制需要与ARP2/3结合，这些数据表明Gadkin是细胞膜上ARP2/3功能的负调节因子。
Regulation of actin dynamics is key to many cell physiological processes, ranging from protrusion formation and control of cell shape to cellular motility, endocytosis, and vesicle movement. The actin-related protein (ARP)2/3 complex is a major actin nucleator organizing branched filament networks in lamellipodial protrusions and during cell migration downstream of nucleation-promoting factors (NPFs). Although many NPFs have been characterized in detail, only few ARP2/3 inhibitors are known. Here, we identify the trans-Golgi network (TGN)/endosomally localized adaptor protein (AP)-1-associated adaptor protein Gadkin as a negative regulator of ARP2/3 function. Loss of Gadkin is associated with a partial redistribution of ARP2/3 to the plasma membrane and with increased cell spreading and migration, phenotypes that depend on the presence of a functional ARP2/3 complex. Gadkin directly binds to ARP2/3 via a conserved tryptophan-based acidic cluster motif reminiscent of ARP2/3-binding sequences of NPFs but fails to facilitate ARP2/3-mediated actin assembly. Consistent with an inhibitory role of Gadkin on ARP2/3 function, ARP2/3 is found on motile Gadkin-containing endosomal vesicles under migration-inhibiting conditions from where it relocalizes to the plasma membrane following activation of NPFs. Together with the observation that Gadkin-mediated inhibition of cell spreading requires its binding to ARP2/3, these data indicate that Gadkin is a negative regulator of ARP2/3 function present on intracellular membranes.