Arf GTP-binding proteins and membrane traffic

Arf GTP 结合蛋白和膜运输

• 批准号: 8939753
• 负责人: Julie G Donaldson
• 金额: $ 17.13万
• 依托单位: NATIONAL HEART, LUNG, AND BLOOD INSTITUTE
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/8939753
• 关键词: Actins; Attention; Cell membrane; Cell surface; Cells; Cytoskeleton; DNA Sequence Rearrangement; Focal Adhesions; GTP-Binding Proteins; Generations; Goals; Golgi Apparatus; Guanine Nucleotide Exchange Factors; Guanosine Triphosphate; Laboratories; Lead; Membrane Protein Traffic; Organelles; Output; Pathway interactions; Phorbol Esters; Phospholipase D; Phosphotransferases; Protein Kinase C; Proteins; Signal Transduction; Sorting - Cell Movement; Structure; Tumor Promoters; Vesicle; insight; interest; phosphatidylinositol 4-phosphate; protein function; response; scaffold; src-Family Kinases

The Arf6 GTP-binding protein has been shown to function at the plasma membrane to coordinate an endosomal membrane trafficking pathway and maintain the cortical actin cytoskeleton. More recently, we turned our attention to examining whether other Arf proteins (especially Arf1), typically thought to function at the Golgi complex, could also serve a function at the cell surface. We previously showed that activation of Arf6 at the PM could lead to activation of Arf1 by the recruitment of the ARNO guanine nucleotide exchange factor, which activates Arf1 (Cohen et al., 2007 Mol Biol Cell 18:2244). Now we have shown that Golgi-associated Arfs like Arf1 are required at the plasma membrane to initiate specific cortical actin rearrangements (Caviston et al., 2014). We found that Arf1 is required for the generation of ventral actin structures formed in response to phorbol ester treatment. Phorbol esters like PMA are tumor promoters and lead to the activation of protein kinase C and Src family kinases. These ventral actin structures represent a major re-organization of the cortical actin cytoskeleton and focal adhesions. This adds to the growing list of cellular activities occurring at the plasma membrane that now are thought to involve Arf1. Athough all Arf protein share common effectors (stimulation of phospholipase D, and phosphatidylinositol 4-phosphate 5-kinase), they are activated by different guanine nucleotide exchange factors (GEFs) and inactivated by different GTP-ase activating proteins (GAPs). Furthermore these GEFs and GAPs themselves may have unique signaling and scaffolding functions giving rise to distinct signaling outputs. Our findings confirm the presence of a cascade of Arf functioning at the cell surface and open up new insights into the coordination of Arf functioning in the cell.

Arf6 gtp结合蛋白已被证明在质膜上起作用，协调内体膜运输途径并维持皮质肌动蛋白细胞骨架。最近，我们将注意力转向研究其他通常被认为在高尔基复合体上起作用的Arf蛋白（特别是Arf1）是否也可以在细胞表面起作用。我们之前的研究表明，Arf6在PM处的激活可以通过ARNO鸟嘌呤核苷酸交换因子的募集导致Arf1的激活，而ARNO鸟嘌呤核苷酸交换因子可以激活Arf1 （Cohen et al., 2007 Mol Biol Cell 18:2244）。现在我们已经证明，高尔基蛋白相关的Arfs，如Arf1，是质膜上启动特异性皮质肌动蛋白重排所必需的（Caviston等，2014）。我们发现Arf1是产生腹侧肌动蛋白结构所必需的，腹侧肌动蛋白结构是对磷酯处理的反应。磷酸酯类如PMA是肿瘤促进剂，可导致蛋白激酶C和Src家族激酶的激活。这些腹侧肌动蛋白结构代表了皮质肌动蛋白细胞骨架和局灶黏附的主要重组。这增加了在质膜上发生的越来越多的细胞活动，现在被认为与Arf1有关。尽管所有Arf蛋白具有共同的效应（刺激磷脂酶D和磷脂酰肌醇4-磷酸5激酶），但它们可被不同的鸟嘌呤核苷酸交换因子（gef）激活，并被不同的gtp酶激活蛋白（gap）灭活。此外，这些gef和gap本身可能具有独特的信号和支架功能，从而产生不同的信号输出。我们的发现证实了Arf在细胞表面的级联功能的存在，并为细胞中Arf功能的协调提供了新的见解。