title: New Insights into Mechanisms and Functions of Chemokine (C-X-C Motif) Receptor 4 Heteromerization in Vascular Smooth Muscle.
abstract: Recent evidence suggests that C-X-C chemokine receptor type 4 (CXCR4) heteromerizes with α1A/B-adrenoceptors (AR) and atypical chemokine receptor 3 (ACKR3) and that CXCR4:α1A/B-AR heteromers are important for α₁-AR function in vascular smooth muscle cells (VSMC). Structural determinants for CXCR4 heteromerization and functional consequences of CXCR4:α1A/B-AR heteromerization in intact arteries, however, remain unknown. Utilizing proximity ligation assays (PLA) to visualize receptor interactions in VSMC, we show that peptide analogs of transmembrane-domain (TM) 2 and TM4 of CXCR4 selectively reduce PLA signals for CXCR4:α1A-AR and CXCR4:ACKR3 interactions, respectively. While both peptides inhibit CXCL12-induced chemotaxis, only the TM2 peptide inhibits phenylephrine-induced Ca(2+)-fluxes, contraction of VSMC and reduces efficacy of phenylephrine to constrict isolated arteries. In a Cre-loxP mouse model to delete CXCR4 in VSMC, we observed 60% knockdown of CXCR4. PLA signals for CXCR4:α1A/B-AR and CXCR4:ACKR3 interactions in VSMC, however, remained constant. Our observations point towards TM2/4 of CXCR4 as possible contact sites for heteromerization and suggest that TM-derived peptide analogs permit selective targeting of CXCR4 heteromers. A molecular dynamics simulation of a receptor complex in which the CXCR4 homodimer interacts with α1A-AR via TM2 and with ACKR3 via TM4 is presented. Our findings further imply that CXCR4:α1A-AR heteromers are important for intrinsic α₁-AR function in intact arteries and provide initial and unexpected insights into the regulation of CXCR4 heteromerization in VSMC.
authors.affiliation: Burn and Shock Trauma Research Institute, Department of Surgery, Loyola University Chicago Stritch School of Medicine, 2160 S. First Avenue, Maywood, IL 60153, USA. anevans@lumc.edu.
authors.forename: Ann E
authors.initials: AE
authors.lastname: Evans
authors.affiliation: Burn and Shock Trauma Research Institute, Department of Surgery, Loyola University Chicago Stritch School of Medicine, 2160 S. First Avenue, Maywood, IL 60153, USA. omnamahshiva80@gmail.com.
authors.forename: Abhishek
authors.initials: A
authors.lastname: Tripathi
authors.affiliation: Burn and Shock Trauma Research Institute, Department of Surgery, Loyola University Chicago Stritch School of Medicine, 2160 S. First Avenue, Maywood, IL 60153, USA. hlaporte@luc.edu.
authors.forename: Heather M
authors.initials: HM
authors.lastname: LaPorte
authors.affiliation: Department of Molecular Pharmacology and Therapeutics, Loyola University Chicago Stritch School of Medicine, 2160 S. First Avenue, Maywood, IL 60153, USA. lbruegg@luc.edu.
authors.forename: Lioubov I
authors.initials: LI
authors.lastname: Brueggemann
authors.affiliation: Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, 1100 South Grand Blvd., St. Louis, MO 63104, USA. singh@slu.edu.
authors.forename: Abhay Kumar
authors.initials: AK
authors.lastname: Singh
authors.affiliation: Burn and Shock Trauma Research Institute, Department of Surgery, Loyola University Chicago Stritch School of Medicine, 2160 S. First Avenue, Maywood, IL 60153, USA. lalbee@luc.edu.
authors.forename: Lauren J
authors.initials: LJ
authors.lastname: Albee
authors.affiliation: Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, 1100 South Grand Blvd., St. Louis, MO 63104, USA. kbyron@luc.edu.
authors.forename: Kenneth L
authors.initials: KL
authors.lastname: Byron
authors.affiliation: Cancer and Inflammation Program, National Cancer Institute, PO Box B, Frederick, MD 21702-1201, USA. tarasovn@mail.nih.gov.
authors.forename: Nadya I
authors.initials: NI
authors.lastname: Tarasova
authors.affiliation: Department of Biochemistry, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA. bvolkman@gmail.com.
authors.forename: Brian F
authors.initials: BF
authors.lastname: Volkman
authors.affiliation: Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, 1100 South Grand Blvd., St. Louis, MO 63104, USA. ycho9@slu.edu.
authors.forename: Thomas Yoonsang
authors.initials: TY
authors.lastname: Cho
authors.affiliation: Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, 900 S Ashland, Chicago, IL 60607, USA. vadimg@uic.edu.
authors.forename: Vadim
authors.initials: V
authors.lastname: Gaponenko
authors.affiliation: Burn and Shock Trauma Research Institute, Department of Surgery, Loyola University Chicago Stritch School of Medicine, 2160 S. First Avenue, Maywood, IL 60153, USA. mmajetschak@luc.edu.|Department of Molecular Pharmacology and Therapeutics, Loyola University Chicago Stritch School of Medicine, 2160 S. First Avenue, Maywood, IL 60153, USA. mmajetschak@luc.edu.
authors.forename: Matthias
authors.initials: M
authors.lastname: Majetschak
mesh_terms: D000818:Animals; D001665:Binding Sites; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D002478:Cells, Cultured; D005260:Female; D006801:Humans; D008297:Male; D051379:Mice; D056004:Molecular Dynamics Simulation; D009131:Muscle, Smooth, Vascular / Q000378:metabolism*; D011485:Protein Binding; D055503:Protein Multimerization; D051381:Rats; D017207:Rats, Sprague-Dawley; D018340:Receptors, Adrenergic, alpha-1 / Q000378:metabolism*; D054387:Receptors, CXCR / Q000235:genetics / Q000378:metabolism; D019718:Receptors, CXCR4 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: C501897:Cmkor1 protein, mouse; D018340:Receptors, Adrenergic, alpha-1; D054387:Receptors, CXCR; D019718:Receptors, CXCR4; D002118:Calcium
keywords: (C-X-C motif) receptor 7; G protein-coupled receptor; adrenergic receptor; atypical chemokine receptor 3; blood pressure; receptor heteromer; structural modeling; vascular function