Overlapping and distinct roles for PI3Kbeta and gamma isoforms in S1P-induced migration of human and mouse endothelial cells.
OBJECTIVE
Sphingosine-1-phosphate (S1P), a key regulator of vascular homeostasis and angiogenesis, promotes endothelial cell migration via stimulation of phosphoinositide 3-kinase (PI3K). The aim of this study was to identify the role of PI3Kbeta and gamma isoforms and their downstream effector pathways in mediating endothelial cell migration induced by S1P.


RESULTS
Experiments were performed in human umbilical vein endothelial cells (HUVEC) and murine lung endothelial cells (MLEC). A combination of specific inhibitors, RNA interference, and PI3Kgamma(-/-) mice were used to investigate the role of PI3Kbeta and gamma isoforms in endothelial cell migration. Both PI3Kbeta and gamma isoforms are required for full migration induced by S1P, with Rac1 being a major mediator downstream of both isoforms. In addition, PI3Kbeta but not PI3Kgamma mediates migration via Akt but independent of Rac1 and endothelial NO synthase (eNOS). Further, a S1P-mediated activation of extracellular signal-regulated kinases (Erk) 1/2 contributes to the chemotactic response independent of PI3Kbeta or PI3Kgamma.


CONCLUSIONS
Our data demonstrate that both PI3Kbeta and PI3Kgamma isoforms are required for S1P-induced endothelial cell migration through activation of Rac1. In addition, PI3Kbeta initiates an Akt-sensitive chemotactic response which is independent of Rac1 and eNOS. Thus, PI3Kbeta and PI3Kgamma have both overlapping and distinct roles in regulating endothelial cell migration, which may underlie S1P-triggered angiogenic differentiation.
Center for Molecular Biomedicine, Institute of Molecular Cell Biology, Friedrich Schiller University, Jena, Am Leutragraben 3, 07743 Jena, Germany. regine.heller@mti.uni-jena.de
Regine
R
Heller
Qing
Q
Chang
Gunter
G
Ehrlich
Sherry N
SN
Hsieh
Simone M
SM
Schoenwaelder
Peter J
PJ
Kuhlencordt
Klaus T
KT
Preissner
Emilio
E
Hirsch
Reinhard
R
Wetzker
D000818:Animals; D002465:Cell Movement; D002478:Cells, Cultured; D058544:Class Ib Phosphatidylinositol 3-Kinase; D042783:Endothelial Cells / Q000502:physiology*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism / Q000502:physiology; D008246:Lysophospholipids / Q000502:physiology*; D051379:Mice; D018345:Mice, Knockout; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology*; D010766:Phosphorylation; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000502:physiology; D020830:rac1 GTP-Binding Protein / Q000378:metabolism
D007527:Isoenzymes; D008246:Lysophospholipids; C060506:sphingosine 1-phosphate; D052250:Nitric Oxide Synthase Type III; D019869:Phosphatidylinositol 3-Kinases; D058544:Class Ib Phosphatidylinositol 3-Kinase; C546760:PIK3CG protein, human; C546764:Pik3cg protein, mouse; D051057:Proto-Oncogene Proteins c-akt; D048049:Extracellular Signal-Regulated MAP Kinases; D020830:rac1 GTP-Binding Protein; D013110:Sphingosine