title: Regulation of cytosolic phospholipase A2 phosphorylation by proteolytic cleavage of annexin A1 in activated mast cells.
abstract: Annexin A1 (ANXA1) is cleaved at the N terminal in some activated cells, such as macrophages, neutrophils, and epithelial cells. We previously observed that ANXA1 was proteolytically cleaved in lung extracts prepared from a murine OVA-induced asthma model. However, the cleavage and regulatory mechanisms of ANXA1 in the allergic response remain unclear. In this study, we found that ANXA1 was cleaved in both Ag-induced activated rat basophilic leukemia 2H3 (RBL-2H3) cells and bone marrow-derived mast cells. This cleavage event was inhibited when intracellular Ca(2+) signaling was blocked. ANXA1-knockdown RBL-2H3 cells produced a greater amount of eicosanoids with simultaneous upregulation of cytosolic phospholipase A(2) (cPLA(2)) activity. However, there were no changes in degranulation activity or cytokine production in the knockdown cells. We also found that cPLA(2) interacted with either full-length or cleaved ANXA1 in activated mast cells. cPLA(2) mainly interacted with full-length ANXA1 in the cytosol and cleaved ANXA1 in the membrane fraction. In addition, introduction of a cleavage-resistant ANXA1 mutant had inhibitory effects on both the phosphorylation of cPLA(2) and release of eicosanoids during the activation of RBL-2H3 cells and bone marrow-derived mast cells. These data suggest that cleavage of ANXA1 causes proinflammatory reactions by increasing the phosphorylation of cPLA(2) and production of eicosanoids during mast-cell activation.
authors.affiliation: Laboratory of Cellular and Molecular Biochemistry, School of Life Sciences and Biotechnology, Korea University, Anam-Dong, Sungbuk-Ku, Seoul 136-701, Korea.
authors.forename: Joon Hyun
authors.initials: JH
authors.lastname: Kwon
authors.forename: Jea Hwang
authors.initials: JH
authors.lastname: Lee
authors.forename: Ki Soon
authors.initials: KS
authors.lastname: Kim
authors.forename: Youn Wook
authors.initials: YW
authors.lastname: Chung
authors.forename: Ick Young
authors.initials: IY
authors.lastname: Kim
mesh_terms: D000818:Animals; D017305:Annexin A1 / Q000378:metabolism* / Q000502:physiology; D002460:Cell Line; D002478:Cells, Cultured; D015777:Eicosanoids / Q000096:biosynthesis; D018836:Inflammation Mediators / Q000378:metabolism / Q000502:physiology; D008407:Mast Cells / Q000201:enzymology / Q000276:immunology* / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D054510:Phospholipases A2, Cytosolic / Q000378:metabolism* / Q000502:physiology; D010766:Phosphorylation / Q000276:immunology; D059748:Proteolysis
chemical_list: D017305:Annexin A1; D015777:Eicosanoids; D018836:Inflammation Mediators; D054510:Phospholipases A2, Cytosolic