title: The inositol 5'-phosphatase SHIP-2 negatively regulates IgE-induced mast cell degranulation and cytokine production.
abstract: Aggregation of the high-affinity IgE receptor (FcepsilonRI) on mast cells initiates signaling pathways leading to degranulation and cytokine release. It has been reported that SHIP-1 negatively regulates FcepsilonRI-triggered pathways but it is unknown whether its homologous protein SHIP-2 has the same function. We have used a lentiviral-based RNA interference technique to obtain SHIP-2 knockdown bone marrow-derived mast cells (BMMCs) and have found that elimination of SHIP-2 results in both increased mast cell degranulation and cytokine (IL-4 and IL-13) gene expression upon FcepsilonRI stimulation. Elimination of SHIP-2 from BMMCs has no effect on FcepsilonRI-triggered calcium flux, tyrosine phosphorylation of MAPKs or in actin depolymerization following activation. Rather, we observe that absence of SHIP-2 results in increased activation of the small GTPase Rac-1 and in enhanced microtubule polymerization upon FcepsilonRI engagement. Coimmunoprecipitation experiments in rat basophilic leukemia (RBL 2H3) cells show that SHIP-2 interacts with the FcepsilonRI beta-chain, Gab2 and Lyn and that unlike SHIP-1, it does not associate with SHC in mast cells. Our results report a negative regulatory role of SHIP-2 on mast cell activation that is calcium independent and distinct from the regulation by SHIP-1.
authors.affiliation: Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 12441 Parklawn Drive, Rockville, MD 20852, USA.
authors.forename: Wai-Hang
authors.initials: WH
authors.lastname: Leung
authors.forename: Silvia
authors.initials: S
authors.lastname: Bolland
mesh_terms: D000818:Animals; D001854:Bone Marrow Cells / Q000201:enzymology / Q000276:immunology / Q000378:metabolism; D015550:Cell Degranulation / Q000276:immunology*; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D016207:Cytokines / Q000037:antagonists & inhibitors* / Q000096:biosynthesis; D015536:Down-Regulation / Q000276:immunology*; D005822:Genetic Vectors; D007073:Immunoglobulin E / Q000502:physiology*; D000072181:Inositol Polyphosphate 5-Phosphatases; D016086:Lentivirus / Q000235:genetics; D008407:Mast Cells / Q000166:cytology / Q000201:enzymology / Q000276:immunology* / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D008870:Microtubules / Q000378:metabolism; D000072183:Phosphatidylinositol-3,4,5-Trisphosphate 5-Phosphatases; D010744:Phosphoric Monoester Hydrolases / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D034622:RNA Interference; D051381:Rats
chemical_list: D016207:Cytokines; D007073:Immunoglobulin E; D010744:Phosphoric Monoester Hydrolases; D000072181:Inositol Polyphosphate 5-Phosphatases; C000606433:Inpp5d protein, mouse; C000606435:Inppl1 protein, mouse; C000606436:Inppl1 protein, rat; D000072183:Phosphatidylinositol-3,4,5-Trisphosphate 5-Phosphatases