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Mol Immunol. 2019 Feb;106:12-21. doi: 10.1016/j.molimm.2018.12.016. Epub 2018 Dec 18.

Chemerin-activated functions of CMKLR1 are regulated by G protein-coupled receptor kinase 6 (GRK6) and β-arrestin 2 in inflammatory macrophages.

Author information

1
Thurston Arthritis Research Center and the Department of Medicine, Division of Rheumatology, Allergy, and Immunology, University of North Carolina, Chapel Hill, NC 27599, United States.
2
Thurston Arthritis Research Center and the Department of Medicine, Division of Rheumatology, Allergy, and Immunology, University of North Carolina, Chapel Hill, NC 27599, United States; Duke University, Department of Medicine, Division of Rheumatology and Immunology, Durham, NC 27710, United States.
3
Department of Pharmacology, University of North Carolina, Chapel Hill, NC 27599, United States.
4
Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, NC 27599, United States; Duke University, Department of Medicine, Division of Rheumatology and Immunology, Durham, NC 27710, United States.
5
Department of Physiology & Pharmacology, West Virginia University, Morgantown, WV, 26506, United States.
6
Department of Biostatistics, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC 27599, United States.
7
Yale School of Public Health, New Haven, CT 06510, United States.
8
Thurston Arthritis Research Center and the Department of Medicine, Division of Rheumatology, Allergy, and Immunology, University of North Carolina, Chapel Hill, NC 27599, United States; Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, NC 27599, United States. Electronic address: mbillard@unc.edu.

Abstract

Chemerin receptor (CMKLR1) is a G protein-coupled receptor (GPCR) implicated in macrophage-mediated inflammation and in several forms of human arthritis. Analogous to other GPCR, CMKLR1 is likely regulated by G protein-coupled receptor kinase (GRK) phosphorylation of intracellular domains in an activation-dependent manner, which leads to recruitment and termination of intracellular signaling via desensitization and internalization of the receptor. The ubiquitously expressed GRK family members include GRK2, GRK3, GRK5, and GRK6, but it is unknown which GRK regulates CMKLR1 cellular and signaling functions. Our data show that activation of CMKLR1 by chemerin in primary macrophages leads to signaling and functional outcomes that are regulated by GRK6 and β-arrestin 2. We show that arrestin recruitment to CMKLR1 following chemerin stimulation is enhanced with co-expression of GRK6. Further, internalization of endogenous CMKLR1, following the addition of chemerin, is decreased in inflammatory macrophages from GRK6- and β-arrestin 2-deficient mice. These GRK6- and β-arrestin 2-deficient macrophages display increased migration toward chemerin and altered AKT and Extracellular-signal Related Kinase (ERK) signaling. Our findings show that chemerin-activated CMKLR1 regulation in inflammatory macrophages is largely GRK6 and β-arrestin mediated, which may impact innate immunity and have therapeutic implications in rheumatic disease.

KEYWORDS:

Arrestin; Arthritis; Chemerin; G protein-coupled receptor (GPCR); G protein-coupled receptor kinase (GRK); Macrophage

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