Caviston Juliane P, Cohen Lee Ann, Donaldson Julie G
Cell Biology and Physiology Center, NHLBI, NIH, Bethesda, Maryland.
Cytoskeleton (Hoboken). 2014 Jun;71(6):380-94. doi: 10.1002/cm.21181. Epub 2014 Jun 26.
Arf proteins regulate membrane traffic and organelle structure. Although Arf6 is known to initiate actin-based changes in cell surface architecture, Arf1 may also function at the plasma membrane. Here we show that acute activation of protein kinase C (PKC) induced by the phorbol ester PMA led to the formation of motile actin structures on the ventral surface of Beas-2b cells, a lung bronchial epithelial cell line. Ventral actin structures also formed in PMA-treated HeLa cells that had elevated levels of Arf activation. For both cell types, formation of the ventral actin structures was enhanced by expression of active forms of either Arf1 or Arf6 and by the expression of guanine nucleotide exchange factors that activate these Arfs. By contrast, formation of these structures was blocked by inhibitors of PKC and Src and required phosphatidylinositol 4, 5-bisphosphate, Rac, Arf6, and Arf1. Furthermore, expression of ASAP1, an Arf1 GTPase activating protein (GAP) was more effective at inhibiting the ventral actin structures than was ACAP1, an Arf6 GAP. This study adds to the expanding role for Arf1 in the periphery and identifies a requirement for Arf1, a "Golgi Arf," in the reorganization of the cortical actin cytoskeleton on ventral surfaces, against the substratum.
Arf蛋白调节膜运输和细胞器结构。尽管已知Arf6可引发细胞表面结构中基于肌动蛋白的变化，但Arf1也可能在质膜发挥作用。在此我们表明，佛波酯PMA诱导的蛋白激酶C（PKC）急性激活导致肺支气管上皮细胞系Beas-2b细胞腹侧表面形成动态肌动蛋白结构。在Arf激活水平升高的经PMA处理的HeLa细胞中也形成了腹侧肌动蛋白结构。对于这两种细胞类型，Arf1或Arf6的活性形式的表达以及激活这些Arfs的鸟嘌呤核苷酸交换因子的表达均增强了腹侧肌动蛋白结构的形成。相比之下，这些结构的形成被PKC和Src的抑制剂阻断，并且需要磷脂酰肌醇4,5-二磷酸、Rac、Arf6和Arf1。此外，Arf1 GTP酶激活蛋白（GAP）ASAP1的表达在抑制腹侧肌动蛋白结构方面比Arf6 GAP ACAP1更有效。这项研究增加了Arf1在外周的扩展作用，并确定了“高尔基体Arf”Arf1在腹侧表面对抗基质的皮质肌动蛋白细胞骨架重组中的需求。
