CC chemokine receptor 5 (CCR5) is a G protein-coupled receptor (GPCR) involved in the recruitment of a subset of leukocytes to sites of inflammation. In addition, CCR5 functions as a co-receptor for several strains of the human immunodeficiency virus (HIV). The finding that agonist-induced internalisation of CCR5 can protect susceptible cells from infection in vitro has stimulated research demonstrating that activated receptors are phosphorylated on C-tail serine residues and bind p-arrestins, which couple them to the clathrin-mediated endocytic machinery. After internalisation, receptors are recycled to the cell surface via a perinuclear recycling compartment, identified as the recycling endosome. Here, I extend these findings, demonstrating that CCR5 also traffics through the trans- Golgi network (TGN), and thus, the perinuclear recycling compartment can be considered to comprise both recycling endosome and TGN elements. Moreover, I show that Rabll regulates trafficking through this compartment and that dynamin inhibition blocks the recycling of CCR5. In combination with other electron microscopy studies, my data support the notion that clathrin and dynamin are involved in the recycling of CCR5 from the recycling compartment. Through morphological and biochemical analysis, I also show that p-arrestins maintain an interaction with CCR5 into the recycling compartment. Kinetic analysis of receptor recycling suggests that p-arrestin2 acts a negative regulator of CCR5 recycling but my data do not discount the possibility that p-arrestins couple CCR5 to clathrin to effect recycling. In keeping with the sustained p-arrestin interaction, CCR5 molecules remain phosphorylated as they traffic to the recycling compartment, but contrary to previous reports showing that receptor C-tail phosphorylation is required for high-affinity p-arrestin binding, I show that a phosphorylation-deficient CCR5 mutant undergoes p-arrestin-dependent agonist-induced internalisation. In addition to its relevance for HIV biology and inflammation, this study contributes to an understanding of GPCR trafficking in general.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:505294 |
| Date | January 2008 |
| Creators | Kershaw, Tom |
| Publisher | University College London (University of London) |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://discovery.ucl.ac.uk/1444245/ |
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