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Mutation Induced Functional Alterations in CCR6 – a GPCR Mediator of Inflammation
Author(s) -
Julian Bina,
Gao Kevin,
Harwood Benjamin,
Kopin Alan
Publication year - 2015
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.29.1_supplement.772.15
Subject(s) - c c chemokine receptor type 6 , chemokine receptor , biology , receptor , g protein coupled receptor , signal transduction , mutant , missense mutation , microbiology and biotechnology , transmembrane domain , hek 293 cells , chemokine , chemistry , mutation , genetics , gene
The chemokine receptor subfamily of GPCRs plays a central role in the migration of immune cells. Family member C‐C Chemokine Receptor 6 (CCR6) is associated with the trafficking of the pro‐inflammatory T helper 17 (Th17) cell, and thus is a promising therapeutic target. Genome wide association studies have linked non‐coding polymorphisms in the CCR6 gene to chronic inflammatory diseases (e.g. Rheumatoid Arthritis, Crohn's Disease). However the impact of naturally occurring missense mutations on CCR6 signaling and function remains unknown. We studied ligand dependent and independent Gαi signaling of WT CCR6 and five naturally occurring variants using a Gq5i mediated SRE luciferase reporter assay in HEK293 cells. WT CCR6 was determined to exhibit constitutive activity that accounted for 10‐15% of maximal endogenous ligand (CCL20) induced receptor activation. Compared to WT CCR6, all five variants had decreased ligand independent activity, with mutants A150V and R155W exhibiting the most significant loss. In contrast, the potency for CCL20 was conserved across all receptors. To complement the study of these loss of function variants, we performed an alanine scan across transmembrane domain 6 and have identified several constitutively active CCR6 mutants. Comparable surface expression levels of HA‐tagged receptors do not explain the observed differences in basal signaling. Work is in progress to assess the chemotactic effects of the CCR6 mutants. In future studies, it will be of interest to determine whether naturally occurring CCR6 mutations alter susceptibility to inflammatory disease and infection.