RGS13 Controls G Protein-Coupled Receptor-Evoked Responses of Human Mast Cells

• Published in: The Journal of immunology (1950) 2008-12, Vol.181 (11), p.7882-7890
• Main Authors: Bansal, Geetanjali, DiVietro, Jeffrey A, Kuehn, Hye Sun, Rao, Sudhir, Nocka, Karl H, Gilfillan, Alasdair M, Druey, Kirk M
• Format: Article
• Language: English
• Subjects: Adenosine - immunology; Adenosine - pharmacology; Allergens - genetics; Allergens - immunology; Allergens - pharmacology; Anaphylaxis - genetics; Anaphylaxis - immunology; Animals; Antigens - genetics; Antigens - immunology; Antigens - pharmacology; Calcium - immunology; Cell Degranulation - drug effects; Cell Degranulation - genetics; Cell Degranulation - immunology; Cell Line; Chemokine CXCL12 - immunology; Chemokine CXCL12 - pharmacology; Chemotaxis - drug effects; Chemotaxis - genetics; Chemotaxis - immunology; Complement C5a - immunology; Complement C5a - pharmacology; Humans; Immunoglobulin E - immunology; Immunoglobulin E - pharmacology; Interleukin-8 - genetics; Interleukin-8 - immunology; Ligands; Lysophospholipids - immunology; Lysophospholipids - pharmacology; Mast Cells - immunology; Mice; Phosphorylation - drug effects; Phosphorylation - genetics; Phosphorylation - immunology; Proto-Oncogene Proteins c-akt - genetics; Proto-Oncogene Proteins c-akt - immunology; Receptors, G-Protein-Coupled - agonists; Receptors, G-Protein-Coupled - genetics; Receptors, G-Protein-Coupled - immunology; RGS Proteins - antagonists & inhibitors; RGS Proteins - genetics; RGS Proteins - immunology; RNA, Small Interfering - genetics; Sphingosine - analogs & derivatives; Sphingosine - immunology; Sphingosine - pharmacology
• ISSN: 0022-1767; 1550-6606
• DOI: 10.4049/jimmunol.181.11.7882

IgE-mediated mast cell degranulation and release of vasoactive mediators induced by allergens elicits allergic responses. Although G protein-coupled receptor (GPCR)-induced signals may amplify IgE-dependent degranulation, how GPCR signaling in mast cells is regulated remains incompletely defined. We investigated the role of regulator of G protein signaling (RGS) proteins in the modulation of these pathways in human mast cells. Several RGS proteins were expressed in mast cells including RGS13, which we previously showed inhibited IgE-mediated mast cell degranulation and anaphylaxis in mice. To characterize how RGS13 affects GPCR-mediated functions of human mast cells, we analyzed human mast cell lines (HMC-1 and LAD2) depleted of RGS13 by specific small interfering RNA or short hairpin RNA and HMC-1 cells overexpressing RGS13. Transient RGS13 knockdown in LAD2 cells lead to increased degranulation to sphingosine-1-phosphate but not to IgE-Ag or C3a. Relative to control cells, HMC-1 cells stably expressing RGS13-targeted short hairpin RNA had greater Ca(2+) mobilization in response to several natural GPCR ligands such as adenosine, C5a, sphingosine-1-phosphate, and CXCL12 than wild-type cells. Akt phosphorylation, chemotaxis, and cytokine (IL-8) secretion induced by CXCL12 were also greater in short hairpin RGS13-HMC-1 cells compared with control. RGS13 overexpression inhibited CXCL12-evoked Ca(2+) mobilization, Akt phosphorylation and chemotaxis. These results suggest that RGS13 restricts certain GPCR-mediated biological responses of human mast cells.