Date of Award

2018

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Cell Biology, Neurobiology and Anatomy

Abstract

G protein-coupled receptor (GPCR) heteromerization is rapidly evolving field. Traditionally, GPCRs were thought to behave has independent entities or protomers. However, that line of reasoning has since been brought into question. Currently, it appears that many, if not all, GPCRs signal and function as heteromeric receptor complexes. The roles of GPCR heteromerization are vast and can include: maturation and trafficking; dynamic regulation; allostery and cooperativity; signal transduction; and receptor internalization.

The majority of studies identifying and characterizing GPCR heteromers were performed using recombinant receptors. Only four receptor pairs have been identified and validated in native tissues. The overall objective of this dissertation was to identify and validate additional GPCR heteromeric complexes that are essential for vascular smooth muscle cell function.

Previous studies from our laboratory identified that chemokine (C-X-C motif) receptor type 4 (CXCR4) forms heteromers with α1-AR in human vascular smooth muscle cells (hVSMC). Activation of CXCR4 potentiates α1-AR -mediated responses. Additionally, our laboratory demonstrated that atypical chemokine receptor 3 (ACKR3) activation antagonizes α1-adrenergic receptor (AR)-mediated vasoconstriction in isolated mesenteric arteries. However, the mechanism for this cross-talk remains elusive. Thus, we tested whether ACKR3 forms heteromeric receptor complexes with α1-AR in hVSMC. As many GPCRs can influence vascular reactivity, we also tested whether the arginine vasopressin receptor type 1A (AVPR1A) can also interact with ACKR3 in native cells.

Using proximity ligation assays we identified that ACKR3 forms heteromers with α1A/B/D-AR and AVPR1A in hVSMC. By disrupting the heteromers we were able to establish a biochemical fingerprint for ACKR3:α1-AR and ACKR3:AVPR1A heteromers in hVSMC. The results from our studies indicate that heteromerization with ACKR3 is necessary for effective α1-AR and AVPR1A signaling and function. ACKR3:α1-AR and ACKR3:AVPR1A heteromers may provide potential therapeutic targets to better control vascular reactivity in both healthy and diseased states.

Creative Commons License

Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License.

Available for download on Sunday, May 21, 2023

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