New Insights into Mechanisms and Functions of Chemokine (C-X-C Motif) Receptor 4 Heteromerization in Vascular Smooth Muscle Journal Article

Authors: Evans, A. E.; Tripathi, A; LaPorte, H. M.; Brueggemann, L. I.; Singh, A. K.; Albee, L. J.; Byron, K. L.; Tarasova, N. I.; Volkman, B. F.; Cho, T. Y.; Gaponenko, V.; Majetschak, M
Article 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 alpha1A/B-adrenoceptors (AR) and atypical chemokine receptor 3 (ACKR3) and that CXCR4:alpha1A/B-AR heteromers are important for alpha(1)-AR function in vascular smooth muscle cells (VSMC). Structural determinants for CXCR4 heteromerization and functional consequences of CXCR4:alpha1A/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:alpha1A-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:alpha1A/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 alpha1A-AR via TM2 and with ACKR3 via TM4 is presented. Our findings further imply that CXCR4:alpha1A-AR heteromers are important for intrinsic alpha(1)-AR function in intact arteries and provide initial and unexpected insights into the regulation of CXCR4 heteromerization in VSMC.
Journal Title: International journal of molecular sciences
Volume: 17
Issue: 5
ISSN: 1422-0067; 1422-0067
Publisher: Unknown  
Journal Place: Switzerland
Date Published: 2016
Start Page: 10.3390/ijms17060971
Language: eng
Notes: LR: 20160708; JID: 101092791; OID: NLM: PMC4926503; OTO: NOTNLM; 2016/04/28 [received]; 2016/06/07 [revised]; 2016/06/13 [accepted]; epublish