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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.

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Inhibition of cAMP accumulation by C9 through CMKLR1. A, In human ASMCs stimulated with NKH477 (3 μmol/L), C9 (1 μmol/L) significantly (Student t test; *P<0.05; n=3 patient cell lines) inhibited cAMP accumulation. Pretreatment with CCX832 (100 nmol/L) blocked this response. Responses are expressed as mean±SEM. (B) In rat aorta primed to produce cAMP (see trace), C9 induced greater contractions (▼), compared to a C9 control response from baseline (▼). Responses are shown as % of contraction evoked by 100 mmol/L of KCl and expressed as mean±SEM (n=4 rats). ASMCs indicates aortic smooth muscle cells; CMKLR1, chemokine‐like receptor 1.
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jah31763-fig-0006: Inhibition of cAMP accumulation by C9 through CMKLR1. A, In human ASMCs stimulated with NKH477 (3 μmol/L), C9 (1 μmol/L) significantly (Student t test; *P<0.05; n=3 patient cell lines) inhibited cAMP accumulation. Pretreatment with CCX832 (100 nmol/L) blocked this response. Responses are expressed as mean±SEM. (B) In rat aorta primed to produce cAMP (see trace), C9 induced greater contractions (▼), compared to a C9 control response from baseline (▼). Responses are shown as % of contraction evoked by 100 mmol/L of KCl and expressed as mean±SEM (n=4 rats). ASMCs indicates aortic smooth muscle cells; CMKLR1, chemokine‐like receptor 1.

Mentions: In human ASMCs stimulated with NKH477 to directly activate adenylyl cyclase, addition of C9 caused a significant reduction in the amount of cAMP accumulated. This inhibition of cAMP accumulation by C9 was blocked by CCX832 (Figure 6A), suggesting that C9 is modulating the response through CMKLR1. In preconstricted rat aorta where NKH477 had caused relaxation to the basal state, C9 induced more contraction (pD2=6.42±0.17; Emax=144±17% of that evoked by KCl) than it did in naïve tissue (pD2=6.39±0.22; Emax=62±10%; Figure 6B). Consistent with a role in contraction, these mechanistic studies show that activation of CMKLR1 in the vasculature inhibits cAMP accumulation.


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
Inhibition of cAMP accumulation by C9 through CMKLR1. A, In human ASMCs stimulated with NKH477 (3 μmol/L), C9 (1 μmol/L) significantly (Student t test; *P<0.05; n=3 patient cell lines) inhibited cAMP accumulation. Pretreatment with CCX832 (100 nmol/L) blocked this response. Responses are expressed as mean±SEM. (B) In rat aorta primed to produce cAMP (see trace), C9 induced greater contractions (▼), compared to a C9 control response from baseline (▼). Responses are shown as % of contraction evoked by 100 mmol/L of KCl and expressed as mean±SEM (n=4 rats). ASMCs indicates aortic smooth muscle cells; CMKLR1, chemokine‐like receptor 1.
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Related In: Results  -  Collection

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jah31763-fig-0006: Inhibition of cAMP accumulation by C9 through CMKLR1. A, In human ASMCs stimulated with NKH477 (3 μmol/L), C9 (1 μmol/L) significantly (Student t test; *P<0.05; n=3 patient cell lines) inhibited cAMP accumulation. Pretreatment with CCX832 (100 nmol/L) blocked this response. Responses are expressed as mean±SEM. (B) In rat aorta primed to produce cAMP (see trace), C9 induced greater contractions (▼), compared to a C9 control response from baseline (▼). Responses are shown as % of contraction evoked by 100 mmol/L of KCl and expressed as mean±SEM (n=4 rats). ASMCs indicates aortic smooth muscle cells; CMKLR1, chemokine‐like receptor 1.
Mentions: In human ASMCs stimulated with NKH477 to directly activate adenylyl cyclase, addition of C9 caused a significant reduction in the amount of cAMP accumulated. This inhibition of cAMP accumulation by C9 was blocked by CCX832 (Figure 6A), suggesting that C9 is modulating the response through CMKLR1. In preconstricted rat aorta where NKH477 had caused relaxation to the basal state, C9 induced more contraction (pD2=6.42±0.17; Emax=144±17% of that evoked by KCl) than it did in naïve tissue (pD2=6.39±0.22; Emax=62±10%; Figure 6B). Consistent with a role in contraction, these mechanistic studies show that activation of CMKLR1 in the vasculature inhibits cAMP accumulation.

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&#8208;like receptor 1 (CMKLR1 or ChemR23) and is proposed to activate the &ldquo;orphan&rdquo; G&#8208;protein&#8208;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&ndash;157) contracted human saphenous vein (pD2=7.30&plusmn;0.31) and resistance arteries (pD2=7.05&plusmn;0.54) and increased blood pressure in rats by 9.1&plusmn;1.0&nbsp;mm&nbsp;Hg at 200&nbsp;nmol. Crucially, these in&nbsp;vitro and in&nbsp;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=&asymp;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