Tyrosine Sulfation Regulates Biased Agonism of the Chemokine Receptor CCR2 — ASN Events
  1. Schedule
  2. Session Seven - Poster Session B Including Happy Hour & Trade Display
  3. Tyrosine Sulfation Regulates Biased Agonism of the Chemokine Receptor CCR2

Tyrosine Sulfation Regulates Biased Agonism of the Chemokine Receptor CCR2 (#223)

Martin J Stone 1 , Jessica L Bridgford 1 , Meritxell Canals 2 , Christopher J Millard 1 , Justin P Ludeman 1 , Mark G Hinds 3 , Zil e Huma 1 , Julie Sanchez 1 , Jiann G Pazhamalil 1 , Richard Payne 4
  1. Monash University, Clayton, VIC, Australia
  2. Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
  3. School of Chemistry and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville , VIC, Australia
  4. School of Chemistry, University of Sydney, Sydney, NSW, Australia

Activation of G protein-coupled receptors (GPCRs) can induce a variety of intracellular signals. Biased agonism is the phenomenon by which different agonists induce distinct arrays of signals by activation of the same receptor. In this presentation we: (1) describe biased agonism of the chemokine receptor CCR2; (2) show that the biased agonism is dependent on receptor tyrosine sulfation; and (3) present structural evidence to support a novel mechanism for regulation of chemokine receptor activation.

Activation of chemokine receptors, GPCRs expressed on leukocytes, by their cognate chemokines induces trafficking of leukocytes to sites of inflammation. Chemokine receptors commonly contain sulfated tyrosine residues in their amino-terminal regions, which are critical for recognition of their chemokine ligands.

Chemokine receptor CCR2 is expressed on monocytes/macrophages and activation of CCR2 by the monocyte chemoattractant proteins (MCP-1, -2 and -3) induces infiltration of monocytic cells in inflammatory diseases such as atherosclerosis. The existence of multiple chemokine agonists for the same receptor has previously been viewed as redundancy. However, we have now observed that the different MCP proteins exhibit biased agonism of CCR2. Thus, when CCR2 signalling was detected using a Ca2+ mobilisation assay, MCP-1 and MCP-3 had similar potencies to each other and were ~10-fold more potent than MCP-2. In contrast, when receptor signalling was detected using an ERK-1/2 phosphorylation assay, MCP-3 displayed ~10-fold higher potency than both MCP-1 and MCP-2. Moreover, when tyrosine sulfation of CCR2 was blocked by culturing cells in the presence of sodium chlorate, the biased agonism was significantly reduced.

The dependence of CCR2 biased agonism on sulfation suggests a model in which the ability of the chemokines to induce different active conformations of the receptor is dependent on initial interactions with the flexible, sulfated N-terminal tail of the receptor. This model is supported by our recent NMR structure of the chemokine eotaxin-1 bound to the sulfated N-terminal tail of the chemokine receptor CCR3. Ongoing structural, binding and receptor activation experiments and studies of chimeric chemokines are providing insights into the structural mechanism of biased chemokine receptor agonism.