Arl4A和Pak1協同招集至細胞膜有助於維持Pak1活化並促進細胞爬行

Cooperative recruitment of Arl4A and Pak1 to the plasma membrane contributes to sustained Pak1 activation for cell migration

陳冠融(Kuan-Jung Chen)

指導教授 ： 李芳仁

國立臺灣大學/醫學院/分子醫學研究所/博士(2020年)

https://doi.org/10.6342/NTU202000060

摘要

細胞在遷移的過程中，需要協調多條信號通路，包括膜動力和細胞骨架重組。先前研究已顯示，小型GTP酶腺嘌呤核苷二磷酸核糖化因子相似蛋白四A(Arl4A)可以調節高爾基體的組織和肌動蛋白的細胞骨架重塑。然而，對於Arl4A在細胞遷移中所扮演的功能了解並不充足。在本篇論文中，我們發現Arl4A和絲氨酸/蘇氨酸蛋白激酶1 (Pak1)兩者扮演重要角色，通過相互協作募集彼此至質膜，來調控細胞的遷移。首先我們觀察到Arl4A會與Pak1直接性的相互結合，並以GTP依賴性方式將Pak1招募至質膜。在Arl4A缺少的細胞中，纖連蛋白(Fibronectin)所誘導的Pak1至細胞膜的程度有明顯減少。出乎意料的是，我們發現Pak1能招募胞質肉荳蔻酰化缺陷的Arl4A (G2A)突變體至細胞膜上，但與Arl4A結合缺陷型的Pak1就無法招募。此外， 我們發現，Arl4A-Pak1之間的結合，對於Arl4A誘導的細胞遷移是相當重要的。因此，我們推斷Arl4A和Pak1存在反饋調節，其中它們相互招募至細胞膜上造成Pak1的激活，從而通過直接相互作用調節細胞遷移。

關鍵字

Ras家族 ； ADP-核糖基化因子 ； 小型GTP? ； 細胞遷移 ； 絲氨酸/蘇氨酸蛋白激?1

並列摘要

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 Golgi organization and 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 cooperative recruitment of each other to the plasma membrane. We first observed that Arl4A directly interacts with Pak1 and recruits Pak1 to the plasma membrane in a GTP-dependent manner. The fibronectin-induced Pak1 localization at the plasma membrane is reduced in Arl4A-depletion 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 critical 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.

並列關鍵字

Ras superfamily ； ADP-ribosylation factor ； GTPase ； Cell migration ； Pak1

參考文獻

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