title: Phosphatidic acid regulation of PIPKI is critical for actin cytoskeletal reorganization.
abstract: Type I phosphatidylinositol-4-phosphate 5-kinase (PIPKI) is the main enzyme generating the lipid second messenger phosphatidylinositol-4,5-bisphosphate [PI(4,5)P2], which has critical functions in many cellular processes, such as cytoskeletal reorganization, membrane trafficking, and signal transduction. All three members of the PIPKI family are activated by phosphatidic acid (PA). However, how PA regulates the activity and functions of PIPKI have not been fully elucidated. In this study, we identify a PA-binding site on PIPKIγ. Mutation of this site inhibited the PA-stimulated activity and membrane localization of PIPKIγ as well as the formation of actin comets and foci induced by PIPKIγ. We also demonstrate that phospholipase D (PLD) generates a pool of PA involved in PIPKIγ regulation by showing that PLD inhibitors blocked the membrane localization of PIPKIγ and its ability to induce actin cytoskeletal reorganization. Targeting the PIPKIγ PA-binding-deficient mutant to membranes by a membrane localization sequence failed to restore the actin reorganization activity of PIPKIγ, suggesting that PA binding is not only involved in recruiting PIPKIγ to membranes but also may induce a conformational change. Taken together, these results reveal a new molecular mechanism through which PA regulates PIPKI and provides direct evidence that PA is important for the localization and functions of PIPKI in intact cells.
authors.affiliation: Department of Pharmacology and Center for Developmental Genetics, Stony Brook University, Stony Brook, NY 11794, USA.
authors.forename: Akua N
authors.initials: AN
authors.lastname: Roach
authors.forename: Ziqing
authors.initials: Z
authors.lastname: Wang
authors.forename: Ping
authors.initials: P
authors.lastname: Wu
authors.forename: Feng
authors.initials: F
authors.lastname: Zhang
authors.forename: Robin B
authors.initials: RB
authors.lastname: Chan
authors.forename: Yoshiya
authors.initials: Y
authors.lastname: Yonekubo
authors.forename: Gilbert
authors.initials: G
authors.lastname: Di Paolo
authors.forename: Alemayehu A
authors.initials: AA
authors.lastname: Gorfe
authors.forename: Guangwei
authors.initials: G
authors.lastname: Du
mesh_terms: D000199:Actins / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D001665:Binding Sites / Q000187:drug effects; D019556:COS Cells; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D003599:Cytoskeleton / Q000187:drug effects / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D008958:Models, Molecular; D009154:Mutation; D010712:Phosphatidic Acids / Q000494:pharmacology*; D010739:Phospholipase D / Q000037:antagonists & inhibitors / Q000378:metabolism; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D017422:Sequence Analysis, DNA; D013329:Structure-Activity Relationship
chemical_list: D000199:Actins; D004791:Enzyme Inhibitors; D010712:Phosphatidic Acids; D011994:Recombinant Proteins; D017853:Phosphotransferases (Alcohol Group Acceptor); C020077:1-phosphatidylinositol-4-phosphate 5-kinase; D010739:Phospholipase D