Prostaglandin E2 activates and utilizes mTORC2 as a central signaling locus for the regulation of mast cell chemotaxis and mediator release.
Prostaglandin (PG) E(2), a potent mediator produced in inflamed tissues, can substantially influence mast cell responses including adhesion to basement membrane proteins, chemotaxis, and chemokine production. However, the signaling pathways by which PGE(2) induces mast cell chemotaxis and chemokine production remains undefined. In this study, we identified the downstream target of phosphatidylinositol 3-kinase, mammalian target of rapamycin (mTOR), as a key regulator of these responses. In mouse bone marrow-derived mast cells, PGE(2) was found to induce activation of mTORC1 (mTOR complexed to raptor) as indicated by increased p70S6K and 4E-BP1 phosphorylation, and activation of mTORC2 (mTOR complexed to rictor), as indicated by increased phosphorylation of AKT at position Ser(473). Selective inhibition of the mTORC1 cascade by rapamycin or by the use of raptor-targeted shRNA failed to decrease PGE(2)-mediated chemotaxis or chemokine generation. However, inhibition of the mTORC2 cascade through the dual mTORC1/mTORC2 inhibitor Torin, or through rictor-targeted shRNA, resulted in a significant attenuation in PGE(2)-mediated chemotaxis, which was associated with a comparable decrease in actin polymerization. Furthermore, mTORC2 down-regulation decreased PGE(2)-induced production of the chemokine monocyte chemoattractant protein-1 (CCL2), which was linked to a significant reduction in ROS production. These findings are consistent with the conclusion that activation of mTORC2, downstream of PI3K, represents a critical signaling locus for chemotaxis and chemokine release from PGE(2)-activated mast cells.
Kuehn
Hye Sun
HS
Laboratory of Allergic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA.
Jung
Mi-Yeon
MY
Beaven
Michael A
MA
Metcalfe
Dean D
DD
Gilfillan
Alasdair M
AM
D000199:Actins / Q000737:chemistry; D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology; D018932:Chemokine CCL2 / Q000096:biosynthesis; D018925:Chemokines / Q000378:metabolism*; D002633:Chemotaxis / Q000187:drug effects*; D015232:Dinoprostone / Q000494:pharmacology*; D055785:Gene Knockdown Techniques; D008407:Mast Cells / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D000076222:Mechanistic Target of Rapamycin Complex 1; D051379:Mice; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D046912:Multiprotein Complexes; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D015230:Prostaglandin D2 / Q000096:biosynthesis; D055503:Protein Multimerization / Q000187:drug effects; D020836:Protein Structure, Quaternary; D011506:Proteins / Q000378:metabolism; D058308:Receptors, Prostaglandin E, EP3 Subtype / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*; D058570:TOR Serine-Threonine Kinases; D015534:Trans-Activators / Q000037:antagonists & inhibitors / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000037:antagonists & inhibitors / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*
D000199:Actins; D018932:Chemokine CCL2; D018925:Chemokines; D015232:Dinoprostone; D000076222:Mechanistic Target of Rapamycin Complex 1; D020928:Mitogen-Activated Protein Kinases; D046912:Multiprotein Complexes; D019869:Phosphatidylinositol 3-Kinases; D015230:Prostaglandin D2; D011506:Proteins; D058308:Receptors, Prostaglandin E, EP3 Subtype; D058570:TOR Serine-Threonine Kinases; D015534:Trans-Activators; D014157:Transcription Factors; C504923:Crtc2 protein, mouse