The carboxyl terminus of the chemokine receptor CCR3 contains distinct domains which regulate chemotactic signaling and receptor down-regulation in a ligand-dependent manner.
The chemokine receptor CCR3 regulates the chemotaxis of leukocytes implicated in allergic disease, such as eosinophils. Incubation of eosinophils with CCL11, CCL13 or CCL5 resulted in a rapid decrease of cell-surface CCR3 which was replicated using CCR3 transfectants. Progressive truncation of the CCR3 C terminus by 15 amino acids produced three constructs, Delta340, Delta325 and Delta310. Delta340 and Delta325 were able to bind CCL11 with affinities similar to wild-type CCR3. Delta340 transfectants exhibited enhanced migration and reduced receptor down-regulation in response to CCL11 and CCL13. Delta325 transfectants displayed chemotactic responses to CCL11 and CCL13 similar to wild-type CCR3, and had impaired down-regulation when stimulated with CCL13 but not CCL11. In contrast, neither the Delta325 nor Delta340 truncation affected chemotaxis or receptor down-regulation induced by CCL5. Delta310 transfectants bound CCL11 poorly and were biologically inactive. Inhibitors of p38 mitogen-activated protein kinase and PI3-kinase antagonized eosinophil shape change responses and chemotaxis of transfectants to CCL11 and CCL13. In contrast, shape change but not chemotaxis was sensitive to inhibition of the extracellular signal-regulated kinase kinase pathway suggesting differential regulation of the two responses. Thus, the CCR3 C terminus contains distinct domains responsible for the regulation of receptor desensitization and for coupling to chemotactic responses.
Sabroe
Ian
I
Leukocyte Biology Section, Biomedical Sciences Division, Imperial College London, UK.
Jorritsma
Annelies
A
Stubbs
Victoria E L
VE
Xanthou
Georgina
G
Jopling
Louise A
LA
Ponath
Paul D
PD
Williams
Timothy J
TJ
Murphy
Philip M
PM
Pease
James E
JE
D000818:Animals; D054413:Chemokine CCL11; D019742:Chemokines, CC / Q000378:metabolism; D002633:Chemotaxis / Q000502:physiology*; D015536:Down-Regulation; D006801:Humans; D008024:Ligands; D020930:MAP Kinase Kinase Kinases / Q000037:antagonists & inhibitors; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors; D018945:Monocyte Chemoattractant Proteins / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D017434:Protein Structure, Tertiary; D054397:Receptors, CCR3; D019707:Receptors, Chemokine / Q000737:chemistry / Q000378:metabolism*; D015854:Up-Regulation
C515456:CCL11 protein, human; C099677:CCL13 protein, human; C515350:CCR3 protein, human; D054413:Chemokine CCL11; D019742:Chemokines, CC; D008024:Ligands; D018945:Monocyte Chemoattractant Proteins; D054397:Receptors, CCR3; D019707:Receptors, Chemokine; D019869:Phosphatidylinositol 3-Kinases; D020928:Mitogen-Activated Protein Kinases; D020930:MAP Kinase Kinase Kinases