PI3K regulates pleckstrin-2 in T-cell cytoskeletal reorganization

TL Bach, WT Kerr, Y Wang, EM Bauman, P Kine… - Blood, 2007 - ashpublications.org
TL Bach, WT Kerr, Y Wang, EM Bauman, P Kine, EL Whiteman, RS Morgan, EK Williamson…
Blood, 2007ashpublications.org
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 α4β1. A pleckstrin-2 variant containing point
mutations in both PH domains failed to associate with the Jurkat membrane and had no …
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 α4β1. 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.
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