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Author Notes:

To whom correspondence should be addressed: Emory University School of Medicine, Dept. of Pharmacology, 1510 Clifton Rd. NE, Atlanta, GA 30322., E-mail: rhall3@emory.edu.

A. K. and R. A. H. designed experiments and wrote the manuscript.

A. K. performed the experiments. A. K. and R. A. H. analyzed the data and created the figures.

All authors made intellectual contributions to the paper and take responsibility for the data.

We thank Dr. Thomas Kukar (Emory University) for helpful comments on this work and for kindly providing the use of imaging instruments to facilitate these studies.

We also thank members of the Hall laboratory for helpful comments and discussion about the studies described here with special thanks to Anqi Gao for technical assistance in addition to discussion.

The authors declare that they have no conflicts of interest with the contents of this article.

The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

Subjects:

Research Funding:

This work was supported by National Institutes of Health Grant R01-NS72394 (to R. A. H.).

Keywords:

  • Science & Technology
  • Life Sciences & Biomedicine
  • Biochemistry & Molecular Biology
  • BILATERAL FRONTOPARIETAL POLYMICROGYRIA
  • CELL-ADHESION
  • TETHERED AGONIST
  • GPCR
  • ANGIOGENESIS
  • MIGRATION
  • BRAIN
  • GPR56/ADGRG1
  • TRAFFICKING
  • EXPRESSION

Disease-associated extracellular loop mutations in the adhesion G protein-coupled receptor G1 (ADGRG1; GPR56) differentially regulate downstream signaling

Tools:

Journal Title:

Journal of Biological Chemistry

Volume:

Volume 292, Number 23

Publisher:

, Pages 9711-9720

Type of Work:

Article | Final Publisher PDF

Abstract:

Mutations to the adhesion G protein-coupled receptor ADGRG1 (G1; also known as GPR56) underlie the neurological disorder bilateral frontoparietal polymicrogyria. Disease-associated mutations in G1 studied to date are believed to induce complete loss of receptor function through disruption of either receptor trafficking or signaling activity. Given that N-terminal truncation of G1 and other adhesion G protein-coupled receptors has been shown to significantly increase the receptors' constitutive signaling, we examined two different bilateral frontoparietal polymicrogyria-inducing extracellular loop mutations (R565W and L640R) in the context of both full-length and N-terminally truncated (ΔNT) G1. Interestingly, we found that these mutations reduced surface expression of full-length G1 but not G1-ΔNT in HEK-293 cells. Moreover, the mutations ablated receptor-mediated activation of serum response factor luciferase, a classic measure of Gα12/13-mediated signaling, but had no effect on G1-mediated signaling to nuclear factor of activated T cells (NFAT) luciferase. Given these differential signaling results, we sought to further elucidate the pathway by which G1 can activate NFAT luciferase. We found no evidence that ΔNT activation of NFAT is dependent on Gαq/11-mediated or β-arrestin-mediated signaling but rather involves liberation of Gβγ subunits and activation of calcium channels. These findings reveal that disease-associated mutations to the extracellular loops of G1 differentially alter receptor trafficking, depending on the presence of the N terminus, and differentially alter signaling to distinct downstream pathways.

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© 2017 by The American Society for Biochemistry and Molecular Biology, Inc

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