Laboratory of Cellular and Molecular Biology, National Cancer Institute, Bethesda, Maryland, United States of America.
PLoS One. 2010 Jan 7;5(1):e8624. doi: 10.1371/journal.pone.0008624.
Arfs and Arf GTPase-activating proteins (ArfGAPs) are regulators of membrane trafficking and actin dynamics in mammalian cells. In this study, we identified a primordial Arf, ArfA, and two ArfGAPs (ACAP-A/B) containing BAR, PH, ArfGAP and Ankyrin repeat domains in the eukaryote Dictyostelium discoideum. In vitro, ArfA has similar nucleotide binding properties as mammalian Arfs and, with GTP bound, is a substrate for ACAP-A and B. We also investigated the physiological functions of ACAP-A/B by characterizing cells lacking both ACAP-A and B. Although ACAP-A/B knockout cells showed no defects in cell growth, migration or chemotaxis, they exhibited abnormal actin protrusions and approximately 50% reduction in spore yield. We conclude that while ACAP-A/B have a conserved biochemical mechanism and effect on actin organization, their role in migration is not conserved. The absence of an effect on Dictyostelium migration may be due to a specific requirement for ACAPs in mesenchymal migration, which is observed in epithelial cancer cells where most studies of mammalian ArfGAPs were performed.
Arfs 和 Arf GTPase 激活蛋白 (ArfGAPs) 是哺乳动物细胞中膜运输和肌动蛋白动力学的调节剂。在这项研究中，我们在真核生物盘基网柄菌中鉴定了一种原始的 Arf（ArfA）和两种含有 BAR、PH、ArfGAP 和锚蛋白重复结构域的 ArfGAP（ACAP-A/B）。在体外，ArfA 具有与哺乳动物 Arfs 相似的核苷酸结合特性，并且与 GTP 结合时，是 ACAP-A 和 B 的底物。我们还通过表征缺失 ACAP-A 和 B 的细胞来研究 ACAP-A/B 的生理功能。尽管 ACAP-A/B 缺失细胞在细胞生长、迁移或趋化性方面没有缺陷，但它们表现出异常的肌动蛋白突起和孢子产量减少约 50%。我们得出的结论是，尽管 ACAP-A/B 在肌动蛋白组织方面具有保守的生化机制和作用，但它们在迁移中的作用并不保守。ACAP 对盘基网柄菌迁移没有影响可能是由于其在间质迁移中具有特定的要求，而在大多数哺乳动物 ArfGAP 研究中都观察到了上皮癌细胞中的这种迁移。
