title: Overlapping signaling pathways of sphingosine 1-phosphate and TGF-beta in the murine Langerhans cell line XS52.
abstract: TGF-beta has been defined as a key mediator for the induction and maintenance of immunological tolerance. Concomitantly, it is essential for homeostasis of specialized epithelial dendritic cells, namely, Langerhans cells (LC). Our data reveal that TGF-beta induces migration of the immature LC, XS52, a cell line expressing the signaling components, TGF-beta type I and II receptors and Smad2, 3, and 4 mRNA. TGF-beta stimulation induced transient Smad3/4 oligomerization and Smad3/DNA binding. Antisense oligonucleotides (ASO) targeting Smad3 abrogated TGF-beta-induced XS52 chemotaxis, proving the involvement of this Smad protein in the TGF-beta-dependent migration. In contrast, the typical CCR6-dependent chemotaxis of immature LC induced by CCL20/MIP-3alpha was not affected by Smad3 ASO. Most notably, we also identified the lysophospholipid sphingosine 1-phosphate (S1P) as a potent chemoattractant for immature LC, which expressed mRNA transcripts of lysophospholipid receptors S1P(1-4). Additional experiments with specific ASO showed that the Galpha(i)-coupled receptors S1P(1) and S1P(3) were dominantly involved in the S1P-induced migration. In contrast, lysophosphatidic acid (LPA), also binding to members of the lysophospholipid receptor family, failed to induce XS52 migration. Intriguingly, we raised evidence that TGF-beta and S1P signal transduction pathways are indeed overlapping, as S1P augmented Smad activation and targeted DNA binding with kinetics comparable to TGF-beta. Finally, S1P failed to stimulate XS52 chemotaxis when Smad3 protein expression was abrogated. Thus, our data indicate a cross-communication between S1P and TGF-beta signaling that might be relevant for more than only migratory activities of immature LC.
authors.affiliation: pharmazentrum frankfurt, Clinic of the Johann Wolfgang Goethe-University, Frankfurt/Main, Germany.
authors.forename: Heinfried H
authors.initials: HH
authors.lastname: Radeke
authors.forename: Henrik
authors.initials: H
authors.lastname: von Wenckstern
authors.forename: Kirsten
authors.initials: K
authors.lastname: Stoidtner
authors.forename: Bettina
authors.initials: B
authors.lastname: Sauer
authors.forename: Stefanie
authors.initials: S
authors.lastname: Hammer
authors.forename: Burkhard
authors.initials: B
authors.lastname: Kleuser
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000276:immunology; D002460:Cell Line; D002630:Chemotactic Factors / Q000502:physiology*; D002633:Chemotaxis / Q000276:immunology; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000378:metabolism / Q000502:physiology; D007801:Langerhans Cells / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D008246:Lysophospholipids / Q000494:pharmacology / Q000502:physiology*; D051379:Mice; D012333:RNA, Messenger / Q000502:physiology; D049349:Receptors, Lysosphingolipid / Q000502:physiology; D018125:Receptors, Transforming Growth Factor beta / Q000235:genetics / Q000502:physiology; D015398:Signal Transduction / Q000276:immunology; D051785:Smad Proteins; D051900:Smad3 Protein; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000502:physiology*; D015534:Trans-Activators / Q000096:biosynthesis / Q000378:metabolism / Q000502:physiology; D016212:Transforming Growth Factor beta / Q000502:physiology*
chemical_list: D002630:Chemotactic Factors; D004268:DNA-Binding Proteins; D008246:Lysophospholipids; D012333:RNA, Messenger; D049349:Receptors, Lysosphingolipid; D018125:Receptors, Transforming Growth Factor beta; D051785:Smad Proteins; D051900:Smad3 Protein; C497791:Smad3 protein, mouse; D015534:Trans-Activators; D016212:Transforming Growth Factor beta; C060506:sphingosine 1-phosphate; D013110:Sphingosine; C032881:lysophosphatidic acid