title: PI3K regulates pleckstrin-2 in T-cell cytoskeletal reorganization.
abstract: Pleckstrin-2 is composed of 2 pleckstrin homology (PH) domains and a disheveled-Egl-10-pleckstrin (DEP) domain. A lipid-binding assay revealed that pleckstrin-2 binds with greatest affinity to D3 and D5 phosphoinositides. Pleckstrin-2 expressed in Jurkat T cells bound to the cellular membrane and enhanced actin-dependent spreading only after stimulation of the T-cell antigen receptor or the integrin alpha4beta1. A pleckstrin-2 variant containing point mutations in both PH domains failed to associate with the Jurkat membrane and had no effect on spreading under the same conditions. Although still membrane bound, a pleckstrin-2 variant containing point mutations in the DEP domain demonstrated a decreased ability to induce membrane ruffles and spread. Pleckstrin-2 also colocalized with actin at the immune synapse and integrin clusters via its PH domains. Although pleckstrin-2 can bind to purified D3 and D5 phosphoinositides, the intracellular membrane association of pleckstrin-2 and cell spreading are dependent on D3 phosphoinositides, because these effects were disrupted by pharmacologic inhibition of phosphatidylinositol 3-kinase (PI3K). Our results indicate that pleckstrin-2 uses its modular domains to bind to membrane-associated phosphatidylinositols generated by PI3K, whereby it coordinates with the actin cytoskeleton in lymphocyte spreading and immune synapse formation.
authors.affiliation: Department of Medicine, University of Pennsylvania School of Medicine, and Department of Pathology, Children's Hospital of Philadelphia 19104, USA.
authors.forename: Tami L
authors.initials: TL
authors.lastname: Bach
authors.forename: Wesley T
authors.initials: WT
authors.lastname: Kerr
authors.forename: Yanfeng
authors.initials: Y
authors.lastname: Wang
authors.forename: Eve Marie
authors.initials: EM
authors.lastname: Bauman
authors.forename: Purnima
authors.initials: P
authors.lastname: Kine
authors.forename: Eileen L
authors.initials: EL
authors.lastname: Whiteman
authors.forename: Renell S
authors.initials: RS
authors.lastname: Morgan
authors.forename: Edward K
authors.initials: EK
authors.lastname: Williamson
authors.forename: E Michael
authors.initials: EM
authors.lastname: Ostap
authors.forename: Janis K
authors.initials: JK
authors.lastname: Burkhardt
authors.forename: Gary A
authors.initials: GA
authors.lastname: Koretzky
authors.forename: Morris J
authors.initials: MJ
authors.lastname: Birnbaum
authors.forename: Charles S
authors.initials: CS
authors.lastname: Abrams
mesh_terms: D000199:Actins / Q000378:metabolism; D001665:Binding Sites; D002448:Cell Adhesion; D003599:Cytoskeleton / Q000378:metabolism*; D006801:Humans; D019169:Jurkat Cells; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology / Q000502:physiology*; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology*; D010716:Phosphatidylinositols / Q000378:metabolism; D017354:Point Mutation; D013601:T-Lymphocytes / Q000166:cytology*; D014161:Transduction, Genetic
chemical_list: D000199:Actins; D008565:Membrane Proteins; C120651:PLEK2 protein, human; D010716:Phosphatidylinositols; D019869:Phosphatidylinositol 3-Kinases