Exchange of extracellular domains of CCR1 and CCR5 reveals confined functions in CCL5-mediated cell recruitment.
The chemokine CCL5 recruits monocytes into inflamed tissues by triggering primarily CCR1-mediated arrest on endothelial cells, whereas subsequent spreading is dominated by CCR5. The CCL5-induced arrest can be enhanced by heteromer formation with CXCL4. To identify mechanisms for receptor-specific functions, we employed CCL5 mutants and transfectants expressing receptor chimeras carrying transposed extracellular regions. Mutation of the basic 50s cluster of CCL5, a coordinative site for CCL5 surface presentation, reduced CCR5- but not CCR1-mediated arrest and transmigration. Impaired arrest was restored by exchanging the CCR5-N-terminus for that of CCR1, which supported arrest even without the 50s cluster, whereas mutation of the basic 40s cluster essential for proteoglycan binding of CCL5 could not be rescued. The enhancement of CCL5-induced arrest by CXCL4 was mediated by CCR1 requiring its third extracellular loop. The domain exchanges did not affect formation and co-localisation of receptor dimers, indicating a sensing role of the third extracellular loop for hetero-oligomers in an arrest microenvironment. Our data identify confined targetable regions of CCR1 specialised to facilitate CCL5-induced arrest and enhanced responsiveness to the CXCL4-CCL5 heteromer.
Philipp von Hundelshausen, Institute for Cardiovascular Prevention, Ludwig-Maximilians-University of Munich, Munich, Germany, Tel.: +49 89 5160 4359, Fax: +49 89 5160 4352, E-mail: phundels@med.lmu.de.
Birgit K
BK
Kramp
Remco T A
RT
Megens
Alisina
A
Sarabi
Sabine
S
Winkler
Delia
D
Projahn
Christian
C
Weber
Rory R
RR
Koenen
Philipp
P
von Hundelshausen
D000818:Animals; D002465:Cell Movement / Q000235:genetics; D018946:Chemokine CCL5 / Q000235:genetics / Q000378:metabolism; D032621:DNA Shuffling / Q000379:methods; D019281:Dimerization; D057809:HEK293 Cells; D006801:Humans; D051379:Mice; D009154:Mutation / Q000235:genetics; D010978:Platelet Factor 4 / Q000235:genetics / Q000378:metabolism; D011487:Protein Conformation; D015202:Protein Engineering; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary / Q000235:genetics; D019713:Receptors, CCR5 / Q000235:genetics / Q000378:metabolism*; D019076:Transgenes / Q000235:genetics
D018946:Chemokine CCL5; D019713:Receptors, CCR5; D010978:Platelet Factor 4; C071570:SNF1-related protein kinases; D017346:Protein Serine-Threonine Kinases
Arrest; RANTES; chemokine receptor chimera; chemotaxis; inflammation