Elsevier

Molecular Metabolism

Volume 6, Issue 10, October 2017, Pages 1173-1185
Molecular Metabolism

Original Article
Gαs regulates Glucagon-Like Peptide 1 Receptor-mediated cyclic AMP generation at Rab5 endosomal compartment

https://doi.org/10.1016/j.molmet.2017.08.002Get rights and content
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Highlights

  • Prolonged association of Gαs with activated GLP-1 R contributes to sustained c AMP generation in pancreatic beta cells.

  • Beta arrestin-1 association with the receptor does not attenuate GLP-1R mediated cyclic AMP generation.

  • Rab5A endosomes serve as a niche for sustained endosomal cyclic AMP generation upon GLP-1 receptor activation.

Abstract

Objective

Upon activation, G protein coupled receptors (GPCRs) associate with heterotrimeric G proteins at the plasma membrane to initiate second messenger signaling. Subsequently, the activated receptor experiences desensitization, internalization, and recycling back to the plasma membrane, or it undergoes lysosomal degradation. Recent reports highlight specific cases of persistent cyclic AMP generation by internalized GPCRs, although the functional significance and mechanistic details remain to be defined. Cyclic AMP generation from internalized Glucagon-Like Peptide-1 Receptor (GLP-1R) has previously been reported from our laboratory. This study aimed at deciphering the molecular mechanism by which internalized GLP-R supports sustained cyclic AMP generation upon receptor activation in pancreatic beta cells.

Methods

We studied the time course of cyclic AMP generation following GLP-1R activation with particular emphasis on defining the location where cyclic AMP is generated. Detection involved a novel GLP-1 conjugate coupled with immunofluorescence using specific endosomal markers. Finally, we employed co-immunoprecipitation as well as immunofluorescence to assess the protein–protein interactions that regulate GLP-1R mediated cyclic AMP generation at endosomes.

Results

Our data reveal that prolonged association of G protein α subunit Gαs with activated GLP-1R contributed to sustained cyclic AMP generation at Rab 5 endosomal compartment.

Conclusions

The findings provide the mechanism of endosomal cyclic AMP generation following GLP-1R activation. We identified the specific compartment that serves as an organizing center to generate endosomal cyclic AMP by internalized activated receptor complex.

Keywords

GLP-1 receptor
Rab5
Cyclic AMP
Insulin secretion
Gαs
Beta arrestin-1
Pancreatic beta cells

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