Abstract
Recent observations suggest that atypical chemokine receptor (ACKR)3 and chemokine (C-X-C motif) receptor (CXCR)4 regulate human vascular smooth muscle function through hetero-oligomerization with α1-adrenoceptors. Here, we show that ACKR3 also regulates arginine vasopressin receptor (AVPR)1A. We observed that ACKR3 agonists inhibit arginine vasopressin (aVP)-induced inositol trisphosphate (IP3) production in human vascular smooth muscle cells (hVSMCs) and antagonize aVP-mediated constriction of isolated arteries. Proximity ligation assays, co-immunoprecipitation and bioluminescence resonance energy transfer experiments suggested that recombinant and endogenous ACKR3 and AVPR1A interact on the cell surface. Interference with ACKR3 : AVPR1A heteromerization using siRNA and peptide analogues of transmembrane domains of ACKR3 abolished aVP-induced IP3 production. aVP stimulation resulted in β-arrestin 2 recruitment to AVPR1A and ACKR3. While ACKR3 activation failed to cross-recruit β-arrestin 2 to AVPR1A, the presence of ACKR3 reduced the efficacy of aVP-induced β-arrestin 2 recruitment to AVPR1A. AVPR1A and ACKR3 co-internalized upon agonist stimulation in hVSMC. These data suggest that AVPR1A : ACKR3 heteromers are constitutively expressed in hVSMC, provide insights into molecular events at the heteromeric receptor complex, and offer a mechanistic basis for interactions between the innate immune and vasoactive neurohormonal systems. Our findings suggest that ACKR3 is a regulator of vascular smooth muscle function and a possible drug target in diseases associated with impaired vascular reactivity.
Highlights
The 7-transmembrane domain (TM) receptors chemokine (C-X-C motif) receptor 4 (CXCR4) and atypical chemokine receptor 3 (ACKR3) are involved in the regulation of vascular function and blood pressure control [1,2,3,4,5,6,7]
We used pressure myography to assess whether CXCR4 and/ or ACKR3 activation influence arginine vasopressin (aVP)-induced constriction of isolated mesenteric resistance arteries. a1-adrenergic receptor (AR)-induced vasoconstriction upon phenylephrine (PE) stimulation was used as a positive control
Our findings are consistent with the recent observation that the potency of CXCL12 to induce b-arrestin recruitment to ACKR3 when measured in a bioluminescence resonance energy transfer (BRET)-based assay was twofold higher than that of CXCL11 [30]
Summary
The 7-transmembrane domain (TM) receptors chemokine (C-X-C motif) receptor 4 (CXCR4) and atypical chemokine receptor 3 (ACKR3) are involved in the regulation of vascular function and blood pressure control [1,2,3,4,5,6,7]. We have shown that simultaneous blockade of CXCR4 and activation of ACKR3 with the synthetic ligand TC14012 result in vasodilatory shock and cardiovascular collapse in normal animals [7] It appears unlikely, that these effects can be attributed exclusively to ACKR3-mediated inhibition of a1-AR in vascular smooth muscle, suggesting additional interactions between ACKR3 and the vasoactive neurohormonal system. We show that heteromerization between AVPR1A and ACKR3 facilitates AVPR1A-mediated Gaq signalling and limits aVP-induced b-arrestin 2 recruitment to AVPR1A, and that activation of ACKR3 inhibits aVP-mediated signalling and vasoconstriction These findings suggest that ACKR3 is a regulator of VSMC function, which controls endogenous and clinically important vasopressor actions
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