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A chemical-genetic approach to study G protein regulation of beta cell function in vivo

Jean-Marc Guettier1, Dinesh Gautam, Marco Scarselli

  • 1Molecular Signaling Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA. guettierj@mail.nih.gov

Proceedings of the National Academy of Sciences of the United States of America
|October 28, 2009
PubMed

Insights

Scientists developed a novel chemical-genetic method to activate specific G proteins in pancreatic beta cells. This approach improved insulin release and glucose tolerance in mice, offering new insights into type 2 diabetes.

Area of Science:

  • Endocrinology
  • Molecular Biology
  • Genetics

Background:

  • Pancreatic beta cell dysfunction is central to type 2 diabetes.
  • Heterotrimeric G proteins modulate beta cell function, but their in vivo roles are unclear due to broad tissue expression of receptors.
  • A selective method to study beta cell G protein signaling is needed.

Purpose of the Study:

  • To develop a chemical-genetic strategy for conditional and selective activation of specific G proteins in pancreatic beta cells in vivo.
  • To investigate the functional consequences of activating G(q/11) and G(s) signaling pathways in beta cells.

Main Methods:

  • Created transgenic mouse lines expressing designer G protein-coupled receptors (GPCRs) exclusively in beta cells.
  • Utilized clozapine-N-oxide to activate designer GPCRs, enabling conditional activation of beta cell G(q/11) or G(s) proteins.
  • Assessed insulin secretion, glucose tolerance, beta cell mass, and islet gene expression.

Main Results:

  • Conditional activation of beta cell G(q/11) signaling significantly increased first- and second-phase insulin release.
  • Improved glucose tolerance and elevated beta cell mass were observed in obese, insulin-resistant mice.
  • Selective G(s) pathway stimulation yielded similar metabolic improvements.
  • Pathway-specific changes in islet gene expression were identified.

Conclusions:

  • The developed chemical-genetic approach allows for precise in vivo study of G protein signaling in beta cells.
  • Targeting beta cell G(q/11) and G(s) pathways shows therapeutic potential for improving beta cell function and glucose homeostasis.
  • This strategy provides a powerful tool for dissecting G protein regulation of beta cell function and exploring type 2 diabetes mechanisms.

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