Sphingosine-1-Phosphate Is a Crucial Signal for Migration of Retina Müller Glial Cells.
OBJECTIVE
Migration of Müller glial cells is enhanced in proliferative retinopathies, but the mechanisms involved are ill defined. Sphingosine-1-phosphate (S1P) is a bioactive sphingolipid synthesized by sphingosine kinase (SphK), which promotes proliferation, migration, and inflammation, acting as an intracellular mediator and activating a family of membrane receptors (S1PRs). We investigated whether S1P regulated glial migration.


METHODS
Müller glial cell cultures from rat retinas were supplemented with 5 μM S1P, and migration was evaluated by scratch-wound assays. Cultures were treated with SphK inhibitor 2 (SphKI 2), a SphK1 inhibitor, or with W146 and BML-241, S1P1 and S1P3 antagonists, respectively, to investigate whether Müller glial cells synthesized S1P and S1P-activated S1PRs to stimulate migration. The effects of LY294002, U0126, and SB203580, which are phosphatidylinositol-3 kinase (PI3K), extracellular signal regulated kinase/mitogen-activated protein kinase (ERK/MAPK), and p38 MAPK inhibitors, respectively, on glial migration were determined.


RESULTS
Sphingosine-1-phosphate addition prompted the formation of lamellipodia and enhanced glial migration. SphKI 2 almost completely prevented glial migration in controls; BML-241 inhibited this migration both in controls and in S1P-supplemented cultures, whereas W146 had no significant effect. Pretreatment with LY294002 and U0126 abrogated glial migration; SB203580 decreased it partially, although not significantly.


CONCLUSIONS
Our results suggest that Müller glial cells synthesize S1P, which signals through S1P3 and the PI3K and ERK/MAPK pathways to induce glial migration. As a whole, our data point to a central role for S1P in controlling glial cell motility. Because deregulation of this process is involved in several retinal pathologies, S1P signaling emerges as a potential tool for treating these diseases.
María V
MV
Simón
Facundo H
FH
Prado Spalm
Luis E
LE
Politi
Nora P
NP
Rotstein
D000818:Animals; D002465:Cell Movement / Q000187:drug effects* / Q000502:physiology; D002478:Cells, Cultured; D004791:Enzyme Inhibitors / Q000494:pharmacology; D008246:Lysophospholipids / Q000494:pharmacology* / Q000502:physiology; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors; D009457:Neuroglia / Q000187:drug effects* / Q000502:physiology; D000081082:Phosphoinositide-3 Kinase Inhibitors; D051381:Rats; D017208:Rats, Wistar; D049349:Receptors, Lysosphingolipid; D012160:Retina / Q000166:cytology / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology*; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000494:pharmacology / Q000502:physiology
D004791:Enzyme Inhibitors; D008246:Lysophospholipids; D000081082:Phosphoinositide-3 Kinase Inhibitors; D049349:Receptors, Lysosphingolipid; C060506:sphingosine 1-phosphate; D020928:Mitogen-Activated Protein Kinases; D013110:Sphingosine