Dataset Information

Asymmetrical ligand-induced cross-regulation of chemokine (C-X-C motif) receptor 4 by ?1-adrenergic receptors at the heteromeric receptor complex.

ABSTRACT: Recently, we reported that chemokine (C-X-C motif) receptor (CXCR)4 and atypical chemokine receptor 3 regulate ?1-adrenergic receptors (?1-AR) through the formation of hetero-oligomeric complexes. Whether ?1-ARs also regulate chemokine receptor function within such heteromeric receptor complexes is unknown. We observed that activation of ?1b-AR within the ?1b-AR:CXCR4 heteromeric complex leads to cross-recruitment of ?-arrestin2 to CXCR4, which could not be inhibited with AMD3100. Activation of CXCR4 did not cross-recruit ?-arrestin2 to ?1b-AR. A peptide analogue of transmembrane domain 2 of CXCR4 interfered with ?1b-AR:CXCR4 heteromerization and inhibited ?1b-AR-mediated ?-arrestin2 cross-recruitment. Phenylephrine (PE) induced internalization of CXCR4 in HEK293 cells co-expressing CXCR4 and ?1b-AR and of endogenous CXCR4 in human vascular smooth muscle cells (hVSMC). The latter was detectable despite blockade of CXCR4 with the neutralizing antibody 12G5. hVSMC migrated towards CXCL12 and PE, but not towards a combination of CXCL12 and PE. PE inhibited CXCL12-induced chemotaxis of hVSMC (IC50: 77?±?30?nM). Phentolamine cross-inhibited CXCL12-induced chemotaxis of hVSMC, whereas AMD3100 did not cross-inhibit PE-induced chemotaxis. These data provide evidence for asymmetrical cross-regulation of CXCR4 by ?1-adrenergic receptors within the heteromeric receptor complex. Our findings provide mechanistic insights into the function of ?1-AR:CXCR4 heteromers and suggest alternative approaches to modulate CXCR4 in disease conditions.

SUBMITTER: Gao X

PROVIDER: S-EPMC5807542 | biostudies-literature | 2018 Feb

REPOSITORIES: biostudies-literature

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Publications

Asymmetrical ligand-induced cross-regulation of chemokine (C-X-C motif) receptor 4 by α1-adrenergic receptors at the heteromeric receptor complex.

Gao Xianlong X Albee Lauren J LJ Volkman Brian F BF Gaponenko Vadim V Majetschak Matthias M

Scientific reports 20180209 1

Recently, we reported that chemokine (C-X-C motif) receptor (CXCR)4 and atypical chemokine receptor 3 regulate α1-adrenergic receptors (α1-AR) through the formation of hetero-oligomeric complexes. Whether α1-ARs also regulate chemokine receptor function within such heteromeric receptor complexes is unknown. We observed that activation of α1b-AR within the α1b-AR:CXCR4 heteromeric complex leads to cross-recruitment of β-arrestin2 to CXCR4, wh ...[more]

PMID: 29426850

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Project description:Recently, we reported that chemokine (C-X-C motif) receptor 4 (CXCR4) heteromerizes with α1-adrenergic receptors (AR) on the cell surface of vascular smooth muscle cells, through which the receptors cross-talk. Direct biophysical evidence for CXCR4:α1-AR heteromers, however, is lacking. Here we utilized bimolecular luminescence/fluorescence complementation (BiLC/BiFC) combined with intermolecular bioluminescence resonance energy transfer (BRET) assays in HEK293T cells to evaluate CXCR4:α1a/b/d-AR heteromerization. Atypical chemokine receptor 3 (ACKR3) and metabotropic glutamate receptor 1 (mGlu1R) were utilized as controls. BRET between CXCR4-RLuc (Renilla reniformis) and enhanced yellow fluorescent protein (EYFP)-tagged ACKR3 or α1a/b/d-ARs fulfilled criteria for constitutive heteromerization. BRET between CXCR4-RLuc and EYFP or mGlu1R-EYFP were nonspecific. BRET50 for CXCR4:ACKR3 and CXCR4:α1a/b/d-AR heteromers were comparable. Stimulation of cells with phenylephrine increased BRETmax of CXCR4:α1a/b/d-AR heteromers without affecting BRET50; stimulation with CXCL12 reduced BRETmax of CXCR4:α1a-AR heteromers, but did not affect BRET50 or BRETmax/50 for CXCR4:α1b/d-AR. A peptide analogue of transmembrane domain (TM) 2 of CXCR4 reduced BRETmax of CXCR4:α1a/b/d-AR heteromers and increased BRET50 of CXCR4:α1a/b-AR interactions. A TM4 analogue of CXCR4 did not alter BRET. We observed CXCR4, α1a-AR and mGlu1R homodimerization by BiFC/BiLC, and heteromerization of homodimeric CXCR4 with proto- and homodimeric α1a-AR by BiFC/BiLC BRET. BiFC/BiLC BRET for interactions between homodimeric CXCR4 and homodimeric mGlu1R was nonspecific. Our findings suggest that the heteromerization affinity of CXCR4 for ACKR3 and α1-ARs is comparable, provide evidence for conformational changes of the receptor complexes upon agonist binding and support the concept that proto- and oligomeric CXCR4 and α1-ARs constitutively form higher-order hetero-oligomeric receptor clusters.

Project description:Recently, we provided evidence that α1-adrenergic receptors (ARs) in vascular smooth muscle are regulated by chemokine (C-X-C motif) receptor (CXCR) 4 and atypical chemokine receptor 3 (ACKR3). While we showed that CXCR4 controls α1-ARs through formation of heteromeric receptor complexes in human vascular smooth muscle cells (hVSMCs), the molecular basis underlying cross-talk between ACKR3 and α1-ARs is unknown. We show that ACKR3 agonists inhibit inositol trisphosphate production in hVSMCs on stimulation with phenylephrine. In proximity ligation assays and co-immunoprecipitation experiments, we observed that recombinant and endogenous ACKR3 form heteromeric complexes with α1A/B/D-AR. While small interfering RNA knockdown of ACKR3 in hVSMCs reduced α1B/D-AR:ACKR3, CXCR4:ACKR3, and α1B/D-AR:CXCR4 complexes, small interfering RNA knockdown of CXCR4 reduced α1B/D-AR:ACKR3 heteromers. Phenylephrine-induced inositol trisphosphate production from hVSMCs was abolished after ACKR3 and CXCR4 small interfering RNA knockdown. Peptide analogs of transmembrane domains 2/4/7 of ACKR3 showed differential effects on heteromerization between ACKR3, α1A/B/D-AR, and CXCR4. While the transmembrane domain 2 peptide interfered with α1B/D-AR:ACKR3 and CXCR4:ACKR3 heteromerization, it increased heteromerization between CXCR4 and α1A/B-AR. The transmembrane domain 2 peptide inhibited ACKR3 but did not affect α1b-AR in β-arrestin recruitment assays. Furthermore, the transmembrane domain 2 peptide inhibited phenylephrine-induced inositol trisphosphate production in hVSMCs and attenuated phenylephrine-induced constriction of mesenteric arteries. α1-ARs form hetero-oligomeric complexes with the ACKR3:CXCR4 heteromer, which is required for α1B/D-AR function, and activation of ACKR3 negatively regulates α1-ARs. G protein-coupled receptor hetero-oligomerization is a dynamic process, which depends on the relative abundance of available receptor partners. Endogenous α1-ARs function within a network of hetero-oligomeric receptor complexes.

Project description:We observed in PRESTO-Tango β-arrestin recruitment assays that the α1-adrenergic receptor (AR) antagonist prazosin activates chemokine (C-X-C motif) receptor (CXCR)4. This prompted us to further examine this unexpected pharmacological behavior. We screened a panel of 14 α1/2- and β1/2/3-AR antagonists for CXCR4 and atypical chemokine receptor (ACKR)3 agonist activity in PRESTO-Tango assays against the cognate agonist CXCL12. We observed that multiple α1-AR antagonists activate CXCR4 (CXCL12 = prazosin = cyclazosin > doxazosin) and ACKR3 (CXCL12 = prazosin = cyclazosin > alfuzosin = doxazosin = phentolamine > terazosin = silodosin = tamsulosin). The two strongest CXCR4/ACKR3 activators, prazosin and cyclazosin, were selected for a more detailed evaluation. We found that the drugs dose-dependently activate both receptors in β-arrestin recruitment assays, stimulate ERK1/2 phosphorylation in HEK293 cells overexpressing each receptor, and that their effects on CXCR4 could be inhibited with AMD3100. Both α1-AR antagonists induced significant chemical shift changes in the 1H-13C-heteronuclear single quantum correlation spectrum of CXCR4 and ACKR3 in membranes, suggesting receptor binding. Furthermore, prazosin and cyclazosin induced internalization of endogenous CXCR4/ACKR3 in human vascular smooth muscle cells (hVSMC). While these drugs did not in induce chemotaxis in hVSMC, they inhibited CXCL12-induced chemotaxis with high efficacy and potency (IC50: prazosin-4.5 nM, cyclazosin 11.6 pM). Our findings reveal unexpected pharmacological properties of prazosin, cyclazosin, and likely other α1-AR antagonists. The results of the present study imply that prazosin and cyclazosin are biased or partial CXCR4/ACKR3 agonists, which function as potent CXCL12 antagonists. Our findings could provide a mechanistic basis for previously observed anti-cancer properties of α1-AR antagonists and support the concept that prazosin could be re-purposed for the treatment of disease processes in which CXCR4 and ACKR3 are thought to play significant pathophysiological roles, such as cancer metastases or various autoimmune pathologies.

Dataset Information

Asymmetrical ligand-induced cross-regulation of chemokine (C-X-C motif) receptor 4 by ?1-adrenergic receptors at the heteromeric receptor complex.

Publications

Asymmetrical ligand-induced cross-regulation of chemokine (C-X-C motif) receptor 4 by α<sub>1</sub>-adrenergic receptors at the heteromeric receptor complex.

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