Regulating a G Protein‐Coupled Receptor by Topological Inversion through Regulated Alternative Translocation

Abstract

BackgroundWe have recently reported the first example that ceramide stimulates the topology inversion of a newly synthesized transmembrane protein. This novel regulation, which is designated as Regulated Alternative Translocation (RAT), requires a GXXXN motif in the first transmembrane domain. Utilizing a bioinformatics approach, we have discovered over 100 proteins that contain a GXXXN motif in the first transmembrane domain and therefore can potentially undergo RAT. Greater than 90% of these proteins are G Protein‐Coupled Receptors, including nearly all of the C‐C and C‐X‐C Chemokine Receptors. In the current study, we determine whether C‐C Chemokine Receptor 5 (CCR5) can be regulated through RAT.Study SummaryWe demonstrate though multiple approaches that CCR5 undergoes topological inversion via RAT in response to exogenously added ceramide in transfected cells. In primary macrophages, we demonstrate Lipopolysaccharide (LPS) treatment induces dihydroceramide to catalyze the RAT of CCR5. LPS‐induced RAT of CCR5 is the mechanism by which LPS inhibits chemotaxis of macrophages towards C‐C Motif Chemokine Ligand (CCL5).ConclusionsThis study demonstrates that LPS‐induced dihydroceramide causes the topology inversion of CCR5 through RAT in primary macrophages. The resulting topology inversion of CCR5 prevents macrophage migration towards CCL5. This finding provides a novel regulation of macrophage chemotaxis and suggests that topological inversion through RAT is a general mechanism to regulate G Protein‐Coupled Receptors.Support or Funding InformationNIH GM‐116106 and HL‐20948This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.