Basal and angiopoietin-1-mediated endothelial permeability is regulated by sphingosine kinase-1.
Endothelial cells (ECs) regulate the barrier function of blood vessels. Here we show that basal and angiopoietin-1 (Ang-1)-regulated control of EC permeability is mediated by 2 different functional states of sphingosine kinase-1 (SK-1). Mice depleted of SK-1 have increased vascular leakiness, whereas mice transgenic for SK-1 in ECs show attenuation of leakiness. Furthermore, Ang-1 rapidly and transiently stimulates SK-1 activity and phosphorylation, and induces an increase in intracellular sphingosine-1-phosphate (S1P) concentration. Overexpression of SK-1 resulted in inhibition of permeability similar to that seen for Ang-1, whereas knockdown of SK-1 by small interfering RNA blocked Ang-1-mediated inhibition of permeability. Transfection with SKS225A, a nonphosphorylatable mutant of SK-1, inhibited basal leakiness, and both SKS225A and a dominant-negative SK-1 mutant removed the capacity of Ang-1 to inhibit permeability. These effects were independent of extracellular S1P as knockdown or inhibition of S1P1, S1P2, or S1P3, did not affect the Ang-1 response. Thus, SK-1 levels in ECs powerfully regulate basal permeability in vitro and in vivo. In addition, the Ang-1-induced inhibition of leakiness is mediated through activation of SK-1, defining a new signaling pathway in the Ang-1 regulation of permeability.
Li
Xiaochun
X
Division of Human Immunology, Hanson Institute, Adelaide, Australia.
Stankovic
Milena
M
Bonder
Claudine S
CS
Hahn
Christopher N
CN
Parsons
Michelle
M
Pitson
Stuart M
SM
Xia
Pu
P
Proia
Richard L
RL
Vadas
Mathew A
MA
Gamble
Jennifer R
JR
D019943:Amino Acid Substitution; D042683:Angiopoietin-1 / Q000378:metabolism*; D000818:Animals; D002199:Capillary Permeability / Q000502:physiology*; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000166:cytology / Q000201:enzymology*; D004789:Enzyme Activation / Q000502:physiology; D006801:Humans; D008246:Lysophospholipids / Q000235:genetics / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D020125:Mutation, Missense; D010766:Phosphorylation; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics; D049349:Receptors, Lysosphingolipid / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D013110:Sphingosine / Q000031:analogs & derivatives / Q000235:genetics / Q000378:metabolism; D014162:Transfection; D000099157:Sphingosine Kinase
D042683:Angiopoietin-1; D008246:Lysophospholipids; D017853:Phosphotransferases (Alcohol Group Acceptor); D034741:RNA, Small Interfering; D049349:Receptors, Lysosphingolipid; D013110:Sphingosine; D000099157:Sphingosine Kinase; C060506:sphingosine 1-phosphate