Allosteric modulation of adenosine A1 and cannabinoid 1 receptor signaling by G-peptides

Anja M. Touma, Rabia U. Malik, Tejas Gupte, Sivaraj Sivaramakrishnan

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

While allosteric modulation of GPCR signaling has gained prominence to address the need for receptor specificity, efforts have mainly focused on allosteric sites adjacent to the orthosteric ligand-binding pocket and lipophilic molecules that target transmembrane helices. In this study, we examined the allosteric influence of native peptides derived from the C-terminus of the Gα subunit (G-peptides) on signaling from two Gi-coupled receptors, adenosine A1 receptor (A1R) and cannabinoid receptor 1 (CB1). We expressed A1R and CB1 fusions with G-peptides derived from Gαs, Gαi, and Gαq in HEK 293 cells using systematic protein affinity strength modulation (SPASM) and monitored the impact on downstream signaling in the cell compared to a construct lacking G-peptides. We used agonists N6-Cyclopentyladenosine (CPA) and 5’-N-Ethylcarboxamidoadenosine (NECA) for A1R and 2-Arachidonoylglycerol (2-AG) and WIN 55,212-2 mesylate (WN) for CB1. G-peptides derived from Gαi and Gαq enhance agonist-dependent cAMP inhibition, demonstrating their effect as positive allosteric modulators of Gi-coupled signaling. In contrast, both G-peptides suppress agonist-dependent IP1 levels suggesting that they differentially function as negative allosteric modulators of Gq-coupled signaling. Taken together with our previous studies on Gs-coupled receptors, this study provides an extended model for the allosteric effects of G-peptides on GPCR signaling, and highlights their potential as probe molecules to enhance receptor specificity.

Original languageEnglish (US)
Article numbere00673
JournalPharmacology Research and Perspectives
Volume8
Issue number6
DOIs
StatePublished - Dec 2020

Bibliographical note

Funding Information:
This work was supported by the National Institutes of Health National Institute of General Medical Sciences [Grant 1R35GM126940‐01 to SS] and the National Heart Lung and Blood Institute [5F30HL146089‐02 to A.T]. We thank Ansley Semack for technical assistance. We also thank Michael Ritt for helpful discussions in writing this manuscript.

Publisher Copyright:
© 2020 The Authors. Pharmacology Research & Perspectives published by John Wiley & Sons Ltd, British Pharmacological Society and American Society for Pharmacology and Experimental Therapeutics.

Keywords

  • CB1
  • GTP-binding proteins
  • N(6)-cyclopentyladenosine
  • SCH 442 416
  • adenosine A1
  • adenosine-5’-(N-ethylcarboxamide)
  • cannabinoid
  • receptor
  • receptor
  • signal transduction

PubMed: MeSH publication types

  • Journal Article
  • Research Support, N.I.H., Extramural

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