TY - JOUR
T1 - Mutational analysis of the extracellular disulphide bridges of the atypical chemokine receptor ACKR3/CXCR7 uncovers multiple binding and activation modes for its chemokine and endogenous non-chemokine agonists
AU - Szpakowska, Martyna
AU - Meyrath, Max
AU - Reynders, Nathan
AU - Counson, Manuel
AU - Hanson, Julien
AU - Steyaert, Jan
AU - Chevigné, Andy
N1 - Funding Information:
This study was supported by the Luxembourg Institute of Health (LIH) MESR (grants 20160116 and 20170113), Luxembourg National Research Fund (INTER/FWO “Nanokine” - grant 15/10358798), F.R.S.-FNRS-Télévie (grants 7456814 and 7461515) and F.R.S.-FNRS incentive grant for scientific research (MIS-F.4510.14). MM and NR are the Luxembourg National Research Fund PhD fellows (grants AFR-3004509 and PRIDE-11012546 “NextImmune”). JH is a “Fonds de la Recherche Scientifique” (F.R.S.-FNRS, Belgium) research associate. The authors wish to thank Arkadiusz Rybicki for his technical help and support.
Publisher Copyright:
© 2018 Elsevier Inc.
PY - 2018/7
Y1 - 2018/7
N2 - The atypical chemokine receptor ACKR3/CXCR7 plays crucial roles in numerous physiological processes but also in viral infection and cancer. ACKR3 shows strong propensity for activation and, unlike classical chemokine receptors, can respond to chemokines from both the CXC and CC families as well as to the endogenous peptides BAM22 and adrenomedullin. Moreover, despite belonging to the G protein coupled receptor family, its function appears to be mainly dependent on β-arrestin. ACKR3 has also been shown to continuously cycle between the plasma membrane and the endosomal compartments, suggesting a possible role as a scavenging receptor. So far, the molecular basis accounting for these atypical binding and signalling properties remains elusive. Noteworthy, ACKR3 extracellular domains bear three disulphide bridges. Two of them lie on top of the two main binding subpockets and are conserved among chemokine receptors, and one, specific to ACKR3, forms an intra-N terminus four-residue-loop of so far unknown function. Here, by mutational and functional studies, we examined the impact of the different disulphide bridges for ACKR3 folding, ligand binding and activation. We showed that, in contrast to most classical chemokine receptors, none of the extracellular disulphide bridges was essential for ACKR3 function. However, the disruption of the unique ACKR3 N-terminal loop drastically reduced the binding of CC chemokines whereas it only had a mild impact on CXC chemokine binding. Mutagenesis also uncovered that chemokine and endogenous non-chemokine ligands interact and activate ACKR3 according to distinct binding modes characterized by different transmembrane domain subpocket occupancy and N-terminal loop contribution, with BAM22 mimicking the binding mode of CC chemokine N terminus.
AB - The atypical chemokine receptor ACKR3/CXCR7 plays crucial roles in numerous physiological processes but also in viral infection and cancer. ACKR3 shows strong propensity for activation and, unlike classical chemokine receptors, can respond to chemokines from both the CXC and CC families as well as to the endogenous peptides BAM22 and adrenomedullin. Moreover, despite belonging to the G protein coupled receptor family, its function appears to be mainly dependent on β-arrestin. ACKR3 has also been shown to continuously cycle between the plasma membrane and the endosomal compartments, suggesting a possible role as a scavenging receptor. So far, the molecular basis accounting for these atypical binding and signalling properties remains elusive. Noteworthy, ACKR3 extracellular domains bear three disulphide bridges. Two of them lie on top of the two main binding subpockets and are conserved among chemokine receptors, and one, specific to ACKR3, forms an intra-N terminus four-residue-loop of so far unknown function. Here, by mutational and functional studies, we examined the impact of the different disulphide bridges for ACKR3 folding, ligand binding and activation. We showed that, in contrast to most classical chemokine receptors, none of the extracellular disulphide bridges was essential for ACKR3 function. However, the disruption of the unique ACKR3 N-terminal loop drastically reduced the binding of CC chemokines whereas it only had a mild impact on CXC chemokine binding. Mutagenesis also uncovered that chemokine and endogenous non-chemokine ligands interact and activate ACKR3 according to distinct binding modes characterized by different transmembrane domain subpocket occupancy and N-terminal loop contribution, with BAM22 mimicking the binding mode of CC chemokine N terminus.
KW - ACKR3
KW - Adrenomedullin
KW - BAM22
KW - CXCL12
KW - CXCR4
KW - CXCR7
KW - Chemokine receptor
UR - http://www.scopus.com/inward/record.url?scp=85045006490&partnerID=8YFLogxK
U2 - 10.1016/j.bcp.2018.03.007
DO - 10.1016/j.bcp.2018.03.007
M3 - Article
C2 - 29530506
AN - SCOPUS:85045006490
SN - 0006-2952
VL - 153
SP - 299
EP - 309
JO - Biochemical Pharmacology
JF - Biochemical Pharmacology
ER -