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Chemerin Elicits Potent Constrictor Actions via Chemokine ‐ Like Receptor 1 ( CMKLR 1), not G ‐ Protein ‐ Coupled Receptor 1 ( GPR 1), in Human and Rat Vasculature

View Article: PubMed Central - PubMed

ABSTRACT

Background: Circulating levels of chemerin are significantly higher in hypertensive patients and positively correlate with blood pressure. Chemerin activates chemokine‐like receptor 1 (CMKLR1 or ChemR23) and is proposed to activate the “orphan” G‐protein‐coupled receptor 1 (GPR1), which has been linked with hypertension. Our aim was to localize chemerin, CMKLR1, and GPR1 in the human vasculature and determine whether 1 or both of these receptors mediate vasoconstriction.

Methods and results: Using immunohistochemistry and molecular biology in conduit arteries and veins and resistance vessels, we localized chemerin to endothelium, smooth muscle, and adventitia and found that CMKLR1 and GPR1 were widely expressed in smooth muscle. C9 (chemerin149–157) contracted human saphenous vein (pD2=7.30±0.31) and resistance arteries (pD2=7.05±0.54) and increased blood pressure in rats by 9.1±1.0 mm Hg at 200 nmol. Crucially, these in vitro and in vivo vascular actions were blocked by CCX832, which we confirmed to be highly selective for CMKLR1 over GPR1. C9 inhibited cAMP accumulation in human aortic smooth muscle cells and preconstricted rat aorta, consistent with the observed vasoconstrictor action. Downstream signaling was explored further and, compared to chemerin, C9 showed a bias factor=≈5000 for the Gi protein pathway, suggesting that CMKLR1 exhibits biased agonism.

Conclusions: Our data suggest that chemerin acts at CMKLR1, but not GPR1, to increase blood pressure. Chemerin has an established detrimental role in metabolic syndrome, and these direct vascular actions may contribute to hypertension, an additional risk factor for cardiovascular disease. This study provides proof of principle for the therapeutic potential of selective CMKLR1 antagonists.

No MeSH data available.


Related in: MedlinePlus

Binding and function of CMKLR1 in human tissues. Radiolabeled binding studies reveal that (A) C9 binds to 1 site, with a subnanomolar affinity (KD = 0.53±0.31 nmol/L; Bmax=0.05±0.007 fmol/mg; n=3), and B, unlabeled C9 (▼, pKi=9.11±0.52; n=5) and CCX832 (■, pKi=8.65±0.38; n=6, pink) compete for all the binding of radiolabeled C9 at native receptors. C9 induced a concentration‐dependent contraction of human vessels (blue), which was blocked by pretreatment with CCX832 (100 nmol/L, pink). Raw trace of the response in SV (C) and the corresponding concentration‐response curves to (▼) C9 and (■) C9+100 nmol/L CCX832 in human SV (D; n=6 patients) and resistance arteries (E; (n=5 patients). Responses are shown as % of maximal response to C9 and expressed as mean±SEM. CMKLR1 indicates chemokine‐like receptor 1; SV, saphenous vein.
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jah31763-fig-0004: Binding and function of CMKLR1 in human tissues. Radiolabeled binding studies reveal that (A) C9 binds to 1 site, with a subnanomolar affinity (KD = 0.53±0.31 nmol/L; Bmax=0.05±0.007 fmol/mg; n=3), and B, unlabeled C9 (▼, pKi=9.11±0.52; n=5) and CCX832 (■, pKi=8.65±0.38; n=6, pink) compete for all the binding of radiolabeled C9 at native receptors. C9 induced a concentration‐dependent contraction of human vessels (blue), which was blocked by pretreatment with CCX832 (100 nmol/L, pink). Raw trace of the response in SV (C) and the corresponding concentration‐response curves to (▼) C9 and (■) C9+100 nmol/L CCX832 in human SV (D; n=6 patients) and resistance arteries (E; (n=5 patients). Responses are shown as % of maximal response to C9 and expressed as mean±SEM. CMKLR1 indicates chemokine‐like receptor 1; SV, saphenous vein.

Mentions: Radiolabeled binding studies with [Tyr149][125I]C9, in human SV homogenate, revealed that C9 binds to a single site, with a subnanomolar affinity of KD=0.53±0.31 nmol/L and Bmax=0.05±0.007 fmol/mg (Figure 4A). Unlabeled C9 (pKi=9.11±0.52) and reported CMKLR1 antagonist, CCX832 (pKi=8.65±0.38), compete for all the binding of radiolabeled C9 (Figure 4B), suggesting that C9 is binding only to native CMKLR1 receptors in human SV.


Chemerin Elicits Potent Constrictor Actions via Chemokine ‐ Like Receptor 1 ( CMKLR 1), not G ‐ Protein ‐ Coupled Receptor 1 ( GPR 1), in Human and Rat Vasculature
Binding and function of CMKLR1 in human tissues. Radiolabeled binding studies reveal that (A) C9 binds to 1 site, with a subnanomolar affinity (KD = 0.53±0.31 nmol/L; Bmax=0.05±0.007 fmol/mg; n=3), and B, unlabeled C9 (▼, pKi=9.11±0.52; n=5) and CCX832 (■, pKi=8.65±0.38; n=6, pink) compete for all the binding of radiolabeled C9 at native receptors. C9 induced a concentration‐dependent contraction of human vessels (blue), which was blocked by pretreatment with CCX832 (100 nmol/L, pink). Raw trace of the response in SV (C) and the corresponding concentration‐response curves to (▼) C9 and (■) C9+100 nmol/L CCX832 in human SV (D; n=6 patients) and resistance arteries (E; (n=5 patients). Responses are shown as % of maximal response to C9 and expressed as mean±SEM. CMKLR1 indicates chemokine‐like receptor 1; SV, saphenous vein.
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jah31763-fig-0004: Binding and function of CMKLR1 in human tissues. Radiolabeled binding studies reveal that (A) C9 binds to 1 site, with a subnanomolar affinity (KD = 0.53±0.31 nmol/L; Bmax=0.05±0.007 fmol/mg; n=3), and B, unlabeled C9 (▼, pKi=9.11±0.52; n=5) and CCX832 (■, pKi=8.65±0.38; n=6, pink) compete for all the binding of radiolabeled C9 at native receptors. C9 induced a concentration‐dependent contraction of human vessels (blue), which was blocked by pretreatment with CCX832 (100 nmol/L, pink). Raw trace of the response in SV (C) and the corresponding concentration‐response curves to (▼) C9 and (■) C9+100 nmol/L CCX832 in human SV (D; n=6 patients) and resistance arteries (E; (n=5 patients). Responses are shown as % of maximal response to C9 and expressed as mean±SEM. CMKLR1 indicates chemokine‐like receptor 1; SV, saphenous vein.
Mentions: Radiolabeled binding studies with [Tyr149][125I]C9, in human SV homogenate, revealed that C9 binds to a single site, with a subnanomolar affinity of KD=0.53±0.31 nmol/L and Bmax=0.05±0.007 fmol/mg (Figure 4A). Unlabeled C9 (pKi=9.11±0.52) and reported CMKLR1 antagonist, CCX832 (pKi=8.65±0.38), compete for all the binding of radiolabeled C9 (Figure 4B), suggesting that C9 is binding only to native CMKLR1 receptors in human SV.

View Article: PubMed Central - PubMed

ABSTRACT

Background: Circulating levels of chemerin are significantly higher in hypertensive patients and positively correlate with blood pressure. Chemerin activates chemokine‐like receptor 1 (CMKLR1 or ChemR23) and is proposed to activate the “orphan” G‐protein‐coupled receptor 1 (GPR1), which has been linked with hypertension. Our aim was to localize chemerin, CMKLR1, and GPR1 in the human vasculature and determine whether 1 or both of these receptors mediate vasoconstriction.

Methods and results: Using immunohistochemistry and molecular biology in conduit arteries and veins and resistance vessels, we localized chemerin to endothelium, smooth muscle, and adventitia and found that CMKLR1 and GPR1 were widely expressed in smooth muscle. C9 (chemerin149–157) contracted human saphenous vein (pD2=7.30±0.31) and resistance arteries (pD2=7.05±0.54) and increased blood pressure in rats by 9.1±1.0 mm Hg at 200 nmol. Crucially, these in vitro and in vivo vascular actions were blocked by CCX832, which we confirmed to be highly selective for CMKLR1 over GPR1. C9 inhibited cAMP accumulation in human aortic smooth muscle cells and preconstricted rat aorta, consistent with the observed vasoconstrictor action. Downstream signaling was explored further and, compared to chemerin, C9 showed a bias factor=≈5000 for the Gi protein pathway, suggesting that CMKLR1 exhibits biased agonism.

Conclusions: Our data suggest that chemerin acts at CMKLR1, but not GPR1, to increase blood pressure. Chemerin has an established detrimental role in metabolic syndrome, and these direct vascular actions may contribute to hypertension, an additional risk factor for cardiovascular disease. This study provides proof of principle for the therapeutic potential of selective CMKLR1 antagonists.

No MeSH data available.


Related in: MedlinePlus