The effects of markedly raised intracellular sphingosine kinase-1 activity in endothelial cells.
The enzyme sphingosine kinase-1 (SK1) promotes the formation of sphingosine-1-phosphate (S1P), which is an important survival factor for endothelial cells (EC). Modest increases in intracellular SK1 activity in the EC are known to confer a survival advantage upon the cells. Here, we investigated the effects of more dramatic increases in intracellular SK1 in the EC. We found that these cells show reduced cell survival under conditions of stress, enhanced caspase-3 activity, cell cycle inhibition, and cell-cell junction disruption. We propose that alterations in the phosphorylation state of the enzyme may explain the differential effects on the phenotype with modest versus high levels of enforced expression of SK1. Our results suggest that SK1 activity is subject to control in the EC, and that this control may be lost in conditions involving vascular regression.
Limaye
Vidya
V
Royal Adelaide Hospital, Department of Rheumatology, North Tce, Royal Adelaide Hospital, Adelaide, SA, 5000, Australia. vidya.limaye@health.sa.gov.au
Vadas
Mathew A
MA
Pitson
Stuart M
SM
Gamble
Jennifer R
JR
D017209:Apoptosis; D053148:Caspase 3 / Q000378:metabolism; D002453:Cell Cycle; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000201:enzymology*; D006801:Humans; D008246:Lysophospholipids / Q000096:biosynthesis; D010766:Phosphorylation; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism*; D013110:Sphingosine / Q000031:analogs & derivatives / Q000096:biosynthesis; D013997:Time Factors; D000099157:Sphingosine Kinase
D053148:Caspase 3; D008246:Lysophospholipids; D017853:Phosphotransferases (Alcohol Group Acceptor); D013110:Sphingosine; D000099157:Sphingosine Kinase; C060506:sphingosine 1-phosphate