Synthesis of phosphatidylinositol 4,5-bisphosphate [Pl(4,5)P2], a signaling phospholipid, is primarily carried out by phosphatidylinositol 4- phosphate 5-kinase [Pl(4)P5K], which has been reported to be regulated by RhoA and Rac1. Unexpectedly, we find that the GTPγ/S-dependent activator of Pl(4)P5Kα is the small G protein ADP-ribosylation factor (ARF) and that the activation strictly requires phosphatidic acid, the product of phospholipase D (PLD). In vivo, ARF6, but not ARF1 or ARF5, spatially coincides with Pl(4)P5Kα. This colocalization occurs in ruffling membranes formed upon AlF4 and EGF stimulation and is blocked by dominant-negative ARF6. PLD2 similarly translocates to the ruffles, as does the PH domain of phospholipase Cδ1, indicating locally elevated Pl(4,5)P2. Thus, Pl(4)P5Kα is a downstream effector of ARF6 and when ARF6 is activated by agonist stimulation, it triggers recruitment of a diverse but interactive set of signaling molecules into sites of active cytoskeletal and membrane rearrangement.
|Number of pages||12|
|State||Published - Nov 24 1999|
Bibliographical noteFunding Information:
We are grateful to Drs. U. Kikkawa, Y. Kaziro, J. I. Gordon, and K. Toda for providing pTB701-FLAG, Rac1 G12V and the Rac1 T17N, pBB131 plasmids, and ARF plasmids, respectively. We also thank Drs. H. Yagisawa, M. Fujii, and T. Osumi for providing GFP-PH/PLCδ1, Dr. M. Umeda for the anti-PI(4,5)P 2 antibody, and Dr. H. Taguchi for skillful support in the sequencing of the purified GTPγS-dependent activator of PI(4)P5Kα. This study was supported by research grant from the Ministry of Education, Science, Sports and Culture, Japan to Y. K. and grants from the NIH to A. J. M. (GM50388) and M. A. F. (GM54813). T. Y. and M. Y. are Research Fellows of the Japan Society for the Promotion of Science.
ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology (all)