Sphingosine 1-phosphate mediates chemotaxis of human primary fibroblasts via the S1P-receptor subtypes S1P₁ and S1P₃ and Smad-signalling.
The sphingolipid sphingosine 1-phosphate (S1P) induces chemotaxis of primary fibroblasts. Thus, S1P exhibited a chemotactic effect in a concentration-dependent manner from 10⁻⁶ to 10⁻⁹ M; higher concentrations resulted in a loss of migration, and lower amounts were ineffective to evoke movement toward a concentration gradient of S1P. In congruence with the migratory response, S1P caused an extension of lamellipodia at the cell periphery of human fibroblasts and a rearrangement of the cytoskeleton. These effects were visible by phalloidin staining of actin filaments as well as focal adhesion turnover. As the molecular mechanism of S1P-mediated migration of fibroblasts has not been well characterized, we investigated whether S1P-receptors are involved in the chemotactic response. Indeed, inhibition of G(i) signalling markedly reduced motility towards S1P, suggesting an involvement of S1P-receptor subtypes. Moreover, downregulation of S1P₁ and S1P₃ indicated that these S1P-receptor subtypes are responsible for the chemotactic action of the bioactive sphingolipid. After having identified a crosstalk between Smad-proteins and S1P-signalling, we investigated whether Smad-activation is involved in the chemotactic response induced by S1P. Indeed S1P caused a Smad-activation via the S1P receptor subtypes S1P₁ and S1P₃. Moreover, downregulation of Smad3 diminished the ability of S1P to mediate a chemotactic response in fibroblasts, indicating a crosstalk between TGF-β- and S1P-signalling.
Gil
Pilar Rivera
PR
Institute of Pharmacy, Free University of Berlin and Physics Department, Phillips University of Marburg, Germany.
Japtok
Lukasz
L
Kleuser
Burkhard
B
D002462:Cell Membrane / Q000378:metabolism; D002465:Cell Movement / Q000502:physiology; D002633:Chemotaxis / Q000187:drug effects* / Q000502:physiology; D003599:Cytoskeleton / Q000378:metabolism; D005347:Fibroblasts / Q000166:cytology* / Q000378:metabolism; D006801:Humans; D047468:Immunoprecipitation; D008246:Lysophospholipids / Q000378:metabolism / Q000494:pharmacology*; D049349:Receptors, Lysosphingolipid / Q000378:metabolism*; D015398:Signal Transduction; D051900:Smad3 Protein / Q000378:metabolism*; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology
D008246:Lysophospholipids; D049349:Receptors, Lysosphingolipid; C497790:SMAD3 protein, human; D051900:Smad3 Protein; C060506:sphingosine 1-phosphate; D013110:Sphingosine