Cell migration requires the coordination of multiple signaling pathways involved in membrane dynamics and cytoskeletal rearrangement. The Arf-like small GTPase Arl4A has been shown to modulate actin cytoskeleton remodeling. However, evidence of the function of Arl4A in cell migration is insufficient. Here, we report that Arl4A acts with the serine/threonine protein kinase Pak1 to modulate cell migration through their cooperative recruitment to the plasma membrane. We first observed that Arl4A and its isoform Arl4D interact with Pak1 and Pak2 and showed that Arl4A recruits Pak1 and Pak2 to the plasma membrane. The fibronectin-induced Pak1 localization at the plasma membrane is reduced in Arl4A-depleted cells. Unexpectedly, we found that Pak1, but not Arl4A-binding-defective Pak1, can recruit a cytoplasmic myristoylation-deficient Arl4A-G2A mutant to the plasma membrane. Furthermore, we found that the Arl4A-Pak1 interaction, which is independent of Rac1 binding to Pak1, is required for Arl4A-induced cell migration. Thus, we infer that there is feedback regulation between Arl4A and Pak1, in which they mutually recruit each other to the plasma membrane for Pak1 activation, thereby modulating cell migration through direct interaction.

中文翻译：

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Arl4A 和 Pak1 协同募集到质膜有助于细胞迁移的持续 Pak1 激活。

细胞迁移需要参与膜动力学和细胞骨架重排的多个信号通路的协调。Arf 样小 GTP 酶 Arl4A 已被证明可以调节肌动蛋白细胞骨架重塑。然而，Arl4A 在细胞迁移中的功能证据不足。在这里，我们报告 Arl4A 与丝氨酸/苏氨酸蛋白激酶 Pak1 一起作用，通过它们协同募集到质膜来调节细胞迁移。我们首先观察到 Arl4A 及其亚型 Arl4D 与 Pak1 和 Pak2 相互作用，并表明 Arl4A 将 Pak1 和 Pak2 募集到质膜。在 Arl4A 耗尽的细胞中，纤连蛋白诱导的 Pak1 在质膜上的定位减少。出乎意料的是，我们发现 Pak1（而不是 Arl4A 结合缺陷型 Pak1）可以将细胞质肉豆蔻酰化缺陷的 Arl4A-G2A 突变体招募到质膜上。此外，我们发现 Arl4A-Pak1 相互作用独立于 Rac1 与 Pak1 的结合，是 Arl4A 诱导的细胞迁移所必需的。因此，我们推断Arl4A和Pak1之间存在反馈调节，它们相互招募到质膜上以激活Pak1，从而通过直接相互作用调节细胞迁移。