title: Essential role of class II phosphatidylinositol-3-kinase-C2α in sphingosine 1-phosphate receptor-1-mediated signaling and migration in endothelial cells.
abstract: The phosphatidylinositol (PtdIns) 3-kinase (PI3K) family regulates diverse cellular processes, including cell proliferation, migration, and vesicular trafficking, through catalyzing 3'-phosphorylation of phosphoinositides. In contrast to class I PI3Ks, including p110α and p110β, functional roles of class II PI3Ks, comprising PI3K-C2α, PI3K-C2β, and PI3K-C2γ, are little understood. The lysophospholipid mediator sphingosine 1-phosphate (S1P) plays the important roles in regulating vascular functions, including vascular formation and barrier integrity, via the G-protein-coupled receptors S1P(1-3). We studied the roles of PI3K-C2α in S1P-induced endothelial cell (EC) migration and tube formation. S1P stimulated cell migration and activation of Akt, ERK, and Rac1, the latter of which acts as a signaling molecule essential for cell migration and tube formation, via S1P(1) in ECs. Knockdown of either PI3K-C2α or class I p110β markedly inhibited S1P-induced migration, lamellipodium formation, and tube formation, whereas that of p110α or Vps34 did not. Only p110β was necessary for S1P-iduced Akt activation, but both PI3K-C2α and p110β were required for Rac1 activation. FRET imaging showed that S1P induced Rac1 activation in both the plasma membrane and PtdIns 3-phosphate (PtdIns(3)P)-enriched endosomes. Knockdown of PI3K-C2α but not p110β markedly reduced PtdIns(3)P-enriched endosomes and suppressed endosomal Rac1 activation. Also, knockdown of PI3K-C2α but not p110β suppressed S1P-induced S1P(1) internalization into PtdIns(3)P-enriched endosomes. Finally, pharmacological inhibition of endocytosis suppressed S1P-induced S1P(1) internalization, Rac1 activation, migration, and tube formation. These observations indicate that PI3K-C2α plays the crucial role in S1P(1) internalization into the intracellular vesicular compartment, Rac1 activation on endosomes, and thereby migration through regulating vesicular trafficking in ECs.
authors.affiliation: Department of Physiology, Kanazawa University School of Medicine, 13-1 Takara-machi, Kanazawa, Ishikawa 920-8640, Japan.
authors.forename: Kuntal
authors.initials: K
authors.lastname: Biswas
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Yoshioka
authors.forename: Ken
authors.initials: K
authors.lastname: Asanuma
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Okamoto
authors.forename: Noriko
authors.initials: N
authors.lastname: Takuwa
authors.forename: Takehiko
authors.initials: T
authors.lastname: Sasaki
authors.forename: Yoh
authors.initials: Y
authors.lastname: Takuwa
mesh_terms: D002465:Cell Movement; D002478:Cells, Cultured; D058541:Class II Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000502:physiology*; D004705:Endocytosis; D011992:Endosomes / Q000378:metabolism; D042783:Endothelial Cells / Q000166:cytology; D031541:Fluorescence Resonance Energy Transfer; D015971:Gene Expression Regulation, Enzymologic; D061307:Human Umbilical Vein Endothelial Cells; D006801:Humans; D008246:Lysophospholipids / Q000378:metabolism; D034741:RNA, Small Interfering / Q000378:metabolism; D049349:Receptors, Lysosphingolipid / Q000235:genetics*; D015398:Signal Transduction; D014162:Transfection; D020744:rac GTP-Binding Proteins / Q000378:metabolism
chemical_list: D008246:Lysophospholipids; D034741:RNA, Small Interfering; D049349:Receptors, Lysosphingolipid; D058541:Class II Phosphatidylinositol 3-Kinases; D020744:rac GTP-Binding Proteins; C032881:lysophosphatidic acid