Abstract
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.
Publication types
-
Research Support, N.I.H., Intramural
MeSH terms
-
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
-
RGS Proteins / antagonists & inhibitors
-
RGS Proteins / genetics
-
RGS Proteins / immunology*
-
RNA, Small Interfering / genetics
-
Receptors, G-Protein-Coupled / agonists
-
Receptors, G-Protein-Coupled / genetics
-
Receptors, G-Protein-Coupled / immunology
-
Sphingosine / analogs & derivatives
-
Sphingosine / immunology
-
Sphingosine / pharmacology
Substances
-
Allergens
-
Antigens
-
CXCL12 protein, human
-
CXCL8 protein, human
-
Chemokine CXCL12
-
Interleukin-8
-
Ligands
-
Lysophospholipids
-
RGS Proteins
-
RGS13 protein, human
-
RNA, Small Interfering
-
Receptors, G-Protein-Coupled
-
sphingosine 1-phosphate
-
Immunoglobulin E
-
Complement C5a
-
Proto-Oncogene Proteins c-akt
-
Adenosine
-
Sphingosine
-
Calcium