Glucagon-like peptide-1 receptor dimerization differentially regulates agonist signaling but does not affect small molecule allostery

Kaleeckal G. Harikumar, Denise Wootten, Delia I. Pinon, Cassandra Koole, Alicja M. Ball, Sebastian G.B. Furness, Bim Graham, Maoqing Dong, Arthur Christopoulos, Laurence J. Miller, Patrick M. Sexton

Research output: Contribution to journalArticle

41 Scopus citations

Abstract

The glucagon-like peptide-1 receptor (GLP-1R) is a family B G protein-coupled receptor and an important drug target for the treatment of type II diabetes, with activation of pancreatic GLP-1Rs eliciting glucose-dependent insulin secretion. Currently, approved therapeutics acting at this receptor are peptide based, and there is substantial interest in small molecule modulators for the GLP-1R. Using a variety of resonance energy transfer techniques, we demonstrate that the GLP-1R forms homodimers and that transmembrane helix 4 (TM4) provides the primary dimerization interface. We showthat disruption of dimerization using a TM4 peptide, a minigene construct encoding TM4, or by mutation of TM4, eliminates G protein-dependent high-affinity binding to GLP-1(7-36)NH2 but has selective effects on receptor signaling. There was <10-fold decrease in potency in cAMP accumulation or ERK1/2 phosphorylation assays but marked loss of intracellular calcium mobilization by peptide agonists. In contrast, there was near-complete abrogation of the cAMP response to an allosteric agonist, compound 2, but preservation of ERK phosphorylation. Collectively, this indicates that GLP-1R dimerization is important for control of signal bias. Furthermore,we reveal that two small molecule ligands are unaltered in their ability to allosterically modulate signaling from peptide ligands, demonstrating that these modulators act in cis within a single receptor protomer, and this has important implications for small molecule drug design.

Original languageEnglish (US)
Pages (from-to)18607-18612
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume109
Issue number45
DOIs
StatePublished - Nov 6 2012

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Keywords

  • Allosteric modulation
  • Biased signaling
  • Family B GPCRs
  • G protein-coupled receptors

ASJC Scopus subject areas

  • General

Cite this

Harikumar, K. G., Wootten, D., Pinon, D. I., Koole, C., Ball, A. M., Furness, S. G. B., Graham, B., Dong, M., Christopoulos, A., Miller, L. J., & Sexton, P. M. (2012). Glucagon-like peptide-1 receptor dimerization differentially regulates agonist signaling but does not affect small molecule allostery. Proceedings of the National Academy of Sciences of the United States of America, 109(45), 18607-18612. https://doi.org/10.1073/pnas.1205227109