Premium
G protein‐coupled receptor kinase 2 moderates recruitment of THP ‐1 cells to the endothelium by limiting histamine‐invoked W eibel‐ P alade body exocytosis
Author(s) -
Stevenson N. L.,
MartinMartin B.,
Freeman J.,
KristonVizi J.,
Ketteler R.,
Cutler D. F.
Publication year - 2014
Publication title -
journal of thrombosis and haemostasis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.947
H-Index - 178
eISSN - 1538-7836
pISSN - 1538-7933
DOI - 10.1111/jth.12470
Subject(s) - microbiology and biotechnology , g protein coupled receptor kinase , g protein coupled receptor , beta adrenergic receptor kinase , kinase , receptor , biology , endothelium , signal transduction , chemistry , endocrinology , biochemistry
Summary Background G protein‐coupled receptors ( GPCR s) are a major family of signaling molecules, central to the regulation of inflammatory responses. Their activation upon agonist binding is attenuated by GPCR kinases ( GRK s), which desensitize the receptors through phosphorylation. G protein‐coupled receptor kinase 2( GRK 2) down‐regulation in leukocytes has been closely linked to the progression of chronic inflammatory disorders such as rheumatoid arthritis and multiple sclerosis. Because leukocytes must interact with the endothelium to infiltrate inflamed tissues, we hypothesized that GRK 2 down‐regulation in endothelial cells would also be pro‐inflammatory. Objectives To determine whether GRK 2 down‐regulation in endothelial cells is pro‐inflammatory. Methods si RNA ‐mediated ablation of GRK 2 in human umbilical vein endothelial cells (HUVEC s) was used in analyses of the role of this kinase. Microscopic and biochemical analyses of W eibel‐ P alade body ( WPB ) formation and functioning, live cell imaging of calcium concentrations and video analyses of adhesion of monocyte‐like THP ‐1 cells provide clear evidence of GRK 2 function in histamine activation of endothelial cells. Results G protein‐coupled receptor kinase 2 depletion in HUVEC s increases WPB exocytosis and P‐selectin‐dependent adhesion of THP ‐1 cells to the endothelial surface upon histamine stimulation, relative to controls. Further, live imaging of intracellular calcium concentrations reveals amplified histamine receptor signaling in GRK 2‐depleted cells, suggesting GRK 2 moderates WPB exocytosis through receptor desensitization. Conclusions G protein‐coupled receptor kinase 2 deficiency in endothelial cells results in increased pro‐inflammatory signaling and enhanced leukocyte recruitment to activated endothelial cells. The ability of GRK 2 to modulate initiation of inflammatory responses in endothelial cells as well as leukocytes now places GRK 2 at the apex of control of this finely balanced process.