Inhibition of chemokine receptor function by membrane cholesterol oxidation.
Membrane cholesterol is required to maintain chemokine receptor conformation and function for CXCR4 and CCR5. We previously demonstrated that chemokines preferentially bind to receptors within lipid rafts, which are cholesterol- and sphingolipid-rich membrane microdomains. To further elucidate the role of cholesterol in chemokine receptor function, we examined the effects of membrane cholesterol oxidation by cholesterol oxidase (CO), which enzymatically converts cholesterol to 4-cholesten-3-one. Here, we demonstrate that CO treatment (0.25-2.0 U/ml) of human T cells inhibits CXCL12 (SDF-1alpha) and CCL4 (MIP-1beta) binding to cell surface CXCR4 and CCR5, respectively, resulting in the inhibition of chemokine-mediated intracellular calcium mobilization and chemotaxis. The effects were significantly enhanced by cotreatment with low-dose sphingomyelinase (SMase) (0.125 mU/ml), which produced little inhibitory effect by itself. CO and SMase treatment also inhibited HIV-1 infection through CXCR4, but not virus replication. Similar to the removal of membrane cholesterol, CO/SMase treatment induced conformation changes in the chemokine receptors as detected by differential loss in binding of epitope-specific monoclonal antibodies. We conclude that the native form of cholesterol with the hydroxyl group at C3 is critical to CXCR4 and CCR5 conformation and function.
Laboratory of Immunology, Intramural Research Program, National Institute on Aging, National Institutes of Health, 5600 Nathan Shock Dr., Baltimore, MD 21224-6825, USA.
Dzung H
DH
Nguyen
Dennis D
DD
Taub
D001665:Binding Sites / Q000187:drug effects / Q000502:physiology; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology; D002460:Cell Line; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism*; D054407:Chemokine CCL4; D054377:Chemokine CXCL12; D019743:Chemokines, CXC / Q000378:metabolism; D002633:Chemotaxis / Q000187:drug effects / Q000502:physiology; D002784:Cholesterol / Q000378:metabolism*; D002789:Cholesterol Oxidase / Q000378:metabolism* / Q000494:pharmacology; D000939:Epitopes / Q000187:drug effects / Q000378:metabolism; D015497:HIV-1 / Q000187:drug effects / Q000472:pathogenicity; D006801:Humans; D017665:Hydroxyl Radical / Q000378:metabolism; D019402:Macrophage Inflammatory Proteins / Q000378:metabolism; D008563:Membrane Lipids / Q000378:metabolism*; D008968:Molecular Conformation; D010084:Oxidation-Reduction / Q000187:drug effects; D019713:Receptors, CCR5 / Q000378:metabolism; D019718:Receptors, CXCR4 / Q000378:metabolism; D019707:Receptors, Chemokine / Q000187:drug effects / Q000378:metabolism*; D013108:Sphingomyelin Phosphodiesterase / Q000187:drug effects / Q000378:metabolism; D014779:Virus Replication / Q000187:drug effects / Q000502:physiology
C515255:CXCL12 protein, human; D054407:Chemokine CCL4; D054377:Chemokine CXCL12; D019743:Chemokines, CXC; D000939:Epitopes; D019402:Macrophage Inflammatory Proteins; D008563:Membrane Lipids; D019713:Receptors, CCR5; D019718:Receptors, CXCR4; D019707:Receptors, Chemokine; D017665:Hydroxyl Radical; D002784:Cholesterol; D002789:Cholesterol Oxidase; D013108:Sphingomyelin Phosphodiesterase