IQGAP1 scaffolding links phosphoinositide kinases to cytoskeletal reorganization
IQGAP1 scaffolding links phosphoinositide kinases to cytoskeletal reorganization
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DOI：
10.1016/j.bpj.2022.01.018
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发表时间：
2022-03-01
影响因子：
3.4
通讯作者：
Gericke，Arne
中科院分区：
文献类型：
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作者：
Yerramilli，V. Siddartha;Ross，Alonzo H.;Gericke，Arne
IQGAP1是一种多结构域支架蛋白，通过支架其不同的结合伙伴来协调多个信号通路的方向和影响。然而，IQGAP1支架的空间和时间分辨率仍然不清楚。在这里，我们使用荧光成像和相关方法，允许实时的活细胞变化的IQGAP1定位和复杂的形成在信号过程中。我们发现IQGAP1和PIPKIγ在细胞膜和胞浆中都相互作用。表皮生长因子(EGF)的刺激可以启动细胞骨架的改变，推动细胞液池向质膜移动，从而促进细胞骨架的改变。我们还观察到，大量的胞内IQGAP1-PIPKIγ复合体定位于早期的内小体，在某些情况下形成聚集的簇，在表皮生长因子刺激下变得高度移动。我们的成像研究表明，PIPKIγ和PI3K同时与IQGAP1结合，这可能会加速PI4P转化为细胞骨架改变所需的PI(3，4，5)P3。此外，我们还发现，在表皮生长因子刺激过程中，IQGAP1与两种与细胞骨架变化相关的蛋白质Talin和CDc42与PIPKIγ有关。这些结果直接表明，在表皮生长因子刺激下，IQGAP1在磷脂酰肌醇(通过PIPKIγ)、局部黏附形成(通过Talin)和细胞骨架重组(通过CDC42)之间提供了物理联系。综上所述，我们的结果支持IQGAP1通过将磷脂酰肌醇脂质信号与细胞骨架重组联系起来来调节细胞迁移的重要性。
IQGAP1 is a multidomain scaffold protein that coordinates the direction and impact of multiple signaling pathways by scaffolding its various binding partners. However, the spatial and temporal resolution of IQGAP1 scaffolding remains unclear. Here, we use fluorescence imaging and correlation methods that allow for real-time live-cell changes in IQGAP1 localization and complex formation during signaling. We find that IQGAP1 and PIPKIγ interact on both the plasma membrane and in cytosol. Epidermal growth factor (EGF) stimulation, which can initiate cytoskeletal changes, drives the movement of the cytosolic pool toward the plasma membrane to promote cytoskeletal changes. We also observe that a significant population of cytosolic IQGAP1-PIPKIγ complexes localize to early endosomes, and in some instances form aggregated clusters which become highly mobile upon EGF stimulation. Our imaging studies show that PIPKIγ and PI3K bind simultaneously to IQGAP1, which may accelerate conversion of PI4P to PI(3,4,5)P3that is required for cytoskeletal changes. Additionally, we find that IQGAP1 is responsible for PIPKIγ association with two proteins associated with cytoskeletal changes, talin and Cdc42, during EGF stimulation. These results directly show that IQGAP1 provides a physical link between phosphoinositides (through PIPKIγ), focal adhesion formation (through talin), and cytoskeletal reorganization (through Cdc42) upon EGF stimulation. Taken together, our results support the importance of IQGAP1 in regulating cell migration by linking phosphoinositide lipid signaling with cytoskeletal reorganization.