Sphingosine 1-phosphate dynamically regulates myosin light chain phosphatase activity in human endothelial cells.
Sphingosine 1-phosphate (S1P) is known to induce reorganization of the actin cytoskeleton through activation of the GTPase Rho. We have investigated the dynamic behavior of Rho/Rho kinase-regulated myosin light chain (MLC) phosphatase activity and MLC phosphorylation in Human Umbilical Vein Endothelial Cells (HUVEC) stimulated with S1P. Immediately (30-60 s) after S1P stimulation, MLC phosphatase activity dropped and MLC phosphorylation increased in a Rho/Rho kinase-dependent manner. Shortly thereafter (2 min), MLC phosphatase increased above baseline and MLC phosphorylation correspondingly decreased to near control values. At this time point, formation of actin ruffles and Rac activity assays indicated activation of Rac. Finally, between 5 and 15 min, MLC phosphatase dropped to a plateau below baseline. In parallel, MLC phosphorylation became constantly elevated above control values. These findings indicate that S1P is able to induce dynamic cycles of MLC phosphatase deactivation and activation. This novel feature of S1P could contribute to its chemotactic and angiogenic activity.
Essler
Markus
M
Institut für Prophylaxe und Epidemiologie der Kreislaufkrankheiten, Universität München, Pettenkoferstr. 9, 80336, München, Germany. messler@klp.med.uni-muenchen.de
Retzer
Michaela
M
Ilchmann
Heiko
H
Linder
Stefan
S
Weber
Peter C
PC
D008841:Actin Cytoskeleton / Q000187:drug effects / Q000648:ultrastructure; D004730:Endothelium, Vascular / Q000187:drug effects / Q000201:enzymology* / Q000648:ultrastructure; D006801:Humans; D007700:Kinetics; D008246:Lysophospholipids / Q000494:pharmacology; D018994:Myosin Light Chains / Q000378:metabolism; D043263:Myosin-Light-Chain Phosphatase; D010749:Phosphoprotein Phosphatases / Q000378:metabolism*; D010766:Phosphorylation; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000494:pharmacology*; D020741:rho GTP-Binding Proteins / Q000502:physiology
D008246:Lysophospholipids; D018994:Myosin Light Chains; C060506:sphingosine 1-phosphate; D010749:Phosphoprotein Phosphatases; D043263:Myosin-Light-Chain Phosphatase; D020741:rho GTP-Binding Proteins; D013110:Sphingosine