title: Cytokine IL-6 secretion by trophoblasts regulated via sphingosine-1-phosphate receptor 2 involving Rho/Rho-kinase and Rac1 signaling pathways.
abstract: Various cytokines derived from placental cells are essential for normal placenta development and successful pregnancy. Interleukin-6 (IL-6) is a multifunctional cytokine produced by extravillous and cytotrophoblasts regulating the functions of these cells, e.g. migration, invasion, trophoblast differentiation and proliferation. In macrophages, newly synthesized IL-6 accumulates in the Golgi complex and exits in tubulovesicular carriers fused with recycling endosomes and secreted as a soluble protein. Sphingosine-1-phosphate (S1P) induces various cytokine secretions including IL-6 in different cell types. The signaling mechanisms regulating the IL-6 secretion are unknown. In this study, we found that S1PR2 was the major S1P receptor being expressed in BeWo cells. S1P regulated IL-6 protein secretion in early phase (6 h) and gene expression in later phase (24 h). IL-6 secretion was completely inhibited via inhibitor of transcription (Actinomycin D) or protein synthesis (Cycloheximide) confirming that IL-6 releases constitutively from BeWo cells. By using specific S1PR2 inhibitor JTE-013 and S1PR2 gene silencing, we found that S1PR2 was the main receptor that regulates IL-6 secretion. Furthermore, S1P induced RhoGTPases-dependent pathways that are required for IL-6 secretion. Pretreatment of cells with specific Rho-kinase inhibitor (Y27632) and Rac1 inhibitor (NSC23766) drastically inhibited S1P-induced IL-6 secretion. By using a specific Phosphoinositide 3-kinase (PI3K) inhibitor (LY294002), we found that basal activity of PI3K was required for secretion but was independent of S1P/S1PR2 axis activation. In summary, we report first time that binding of S1P to S1PR2 activates multiple RhoGTPases-dependent pathways that coordinate with PI3K pathway for secretion of IL-6 in BeWo cells.
authors.affiliation: Department of Obstetrics and Gynecology, University of Greifswald, Ferdinand-Sauerbruchstrasse, D-17489 Greifswald, Germany.
authors.forename: Pankaj
authors.initials: P
authors.lastname: Goyal
authors.forename: Daniela
authors.initials: D
authors.lastname: Brünnert
authors.forename: Jens
authors.initials: J
authors.lastname: Ehrhardt
authors.forename: Marike
authors.initials: M
authors.lastname: Bredow
authors.forename: Svea
authors.initials: S
authors.lastname: Piccenini
authors.forename: Marek
authors.initials: M
authors.lastname: Zygmunt
mesh_terms: D000577:Amides / Q000494:pharmacology; D000634:Aminoquinolines / Q000494:pharmacology; D002460:Cell Line; D002867:Chromones / Q000494:pharmacology; D003513:Cycloheximide / Q000494:pharmacology; D003609:Dactinomycin / Q000494:pharmacology; D005260:Female; D006801:Humans; D015850:Interleukin-6 / Q000378:metabolism*; D008246:Lysophospholipids / Q000378:metabolism; D009025:Morpholines / Q000494:pharmacology; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011247:Pregnancy; D011720:Pyrazoles; D011725:Pyridines / Q000494:pharmacology; D011743:Pyrimidines / Q000494:pharmacology; D034622:RNA Interference; D034741:RNA, Small Interfering; D049349:Receptors, Lysosphingolipid / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D013110:Sphingosine / Q000031:analogs & derivatives / Q000378:metabolism; D000081025:Sphingosine-1-Phosphate Receptors; D014327:Trophoblasts / Q000378:metabolism*; D020830:rac1 GTP-Binding Protein / Q000037:antagonists & inhibitors / Q000378:metabolism*; D020741:rho GTP-Binding Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D054460:rho-Associated Kinases / Q000378:metabolism*
chemical_list: D000577:Amides; D000634:Aminoquinolines; D002867:Chromones; D015850:Interleukin-6; C471998:JTE 013; D008246:Lysophospholipids; D009025:Morpholines; C487513:NSC 23766; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011720:Pyrazoles; D011725:Pyridines; D011743:Pyrimidines; D034741:RNA, Small Interfering; D049349:Receptors, Lysosphingolipid; C477522:S1PR2 protein, human; D000081025:Sphingosine-1-Phosphate Receptors; C108830:Y 27632; D003609:Dactinomycin; C060506:sphingosine 1-phosphate; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D003513:Cycloheximide; D054460:rho-Associated Kinases; D020830:rac1 GTP-Binding Protein; D020741:rho GTP-Binding Proteins; D013110:Sphingosine
keywords: IL-6; PI3-kinase; placenta; sphingosine 1-phosphate; trophoblast