1. Cell Biology
  2. Medicine

Glucagon-like peptide-1 receptor activation stimulates PKA-mediated phosphorylation of raptor and this contributes to the weight loss effect of liraglutide

  1. Thao DV Le
  2. Dianxin Liu
  3. Gai-Linn K Besing
  4. Ritika Raghavan
  5. Blair J Ellis
  6. Ryan P Ceddia
  7. Sheila Collins  Is a corresponding author
  8. Julio E Ayala  Is a corresponding author
  1. Vanderbilt University, United States
  2. Vanderbilt University Medical Center, United States
https://doi.org/10.7554/eLife.80944
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Cite this article
  1. Thao DV Le
  2. Dianxin Liu
  3. Gai-Linn K Besing
  4. Ritika Raghavan
  5. Blair J Ellis
  6. Ryan P Ceddia
  7. Sheila Collins
  8. Julio E Ayala
(2023)
Glucagon-like peptide-1 receptor activation stimulates PKA-mediated phosphorylation of raptor and this contributes to the weight loss effect of liraglutide
eLife 12:e80944.
https://doi.org/10.7554/eLife.80944
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Abstract

The canonical target of the glucagon-like peptide-1 receptor (GLP-1R), Protein Kinase A (PKA), has been shown to stimulate mechanistic Target of Rapamycin Complex 1 (mTORC1) by phosphorylating the mTOR-regulating protein Raptor at Ser791 following β-adrenergic stimulation. The objective of these studies is to test whether GLP-1R agonists similarly stimulate mTORC1 via PKA phosphorylation of Raptor at Ser791 and whether this contributes to the weight loss effect of the therapeutic GLP-1R agonist liraglutide. We measured phosphorylation of the mTORC1 signaling target ribosomal protein S6 in Chinese Hamster Ovary cells expressing GLP-1R (CHO-Glp1r) treated with liraglutide in combination with PKA inhibitors. We also assessed liraglutide-mediated phosphorylation of the PKA substrate RRXS*/T* motif in CHO-Glp1r cells expressing Myc-tagged wild-type (WT) Raptor or a PKA-resistant (Ser791Ala) Raptor mutant. Finally, we measured the body weight response to liraglutide in WT mice and mice with a targeted knock-in of PKA-resistant Ser791Ala Raptor. Liraglutide increased phosphorylation of S6 and the PKA motif in WT Raptor in a PKA-dependent manner but failed to stimulate phosphorylation of the PKA motif in Ser791Ala Raptor in CHO-Glp1r cells. Lean Ser791Ala Raptor knock-in mice were resistant to liraglutide-induced weight loss but not setmelanotide-induced (melanocortin-4 receptor-dependent) weight loss. Diet-induced obese Ser791Ala Raptor knock-in mice were not resistant to liraglutide-induced weight loss; however, there was weight-dependent variation such that there was a tendency for obese Ser791Ala Raptor knock-in mice of lower relative body weight to be resistant to liraglutide-induced weight loss compared to weight-matched controls. Together, these findings suggest that PKA-mediated phosphorylation of Raptor at Ser791 contributes to liraglutide-induced weight loss.

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All data generated or analysed during this study are included in the manuscript and supporting file.

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Author details

  1. Thao DV Le

    Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, United States
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-6242-2562

  2. Dianxin Liu

    Department of Medicine, Vanderbilt University Medical Center, Nashville, United States
    Competing interests
    The authors declare that no competing interests exist.

  3. Gai-Linn K Besing

    Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, United States
    Competing interests
    The authors declare that no competing interests exist.

  4. Ritika Raghavan

    Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, United States
    Competing interests
    The authors declare that no competing interests exist.

  5. Blair J Ellis

    Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, United States
    Competing interests
    The authors declare that no competing interests exist.

  6. Ryan P Ceddia

    Department of Medicine, Vanderbilt University Medical Center, Nashville, United States
    Competing interests
    The authors declare that no competing interests exist.

  7. Sheila Collins

    Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, United States
    For correspondence
    sheila.collins@vumc.org
    Competing interests
    The authors declare that no competing interests exist.

  8. Julio E Ayala

    Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, United States
    For correspondence
    julio.e.ayala@vanderbilt.edu
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0003-3224-2365

Funding

National Institutes of Health (R01DK097361)

  • Julio E Ayala

National Institutes of Health (R01DK116625)

  • Sheila Collins

National Institutes of Health (S10OD028455)

  • Julio E Ayala

National Institutes of Health (R01DK132852)

  • Julio E Ayala

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Ethics

Animal experimentation: Procedures were approved by the Institutional Animal Care and Use Committee at Vanderbilt University (Protocol #M100158).

Copyright

© 2023, Le et al.

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.

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  1. Thao DV Le
  2. Dianxin Liu
  3. Gai-Linn K Besing
  4. Ritika Raghavan
  5. Blair J Ellis
  6. Ryan P Ceddia
  7. Sheila Collins
  8. Julio E Ayala
(2023)
Glucagon-like peptide-1 receptor activation stimulates PKA-mediated phosphorylation of raptor and this contributes to the weight loss effect of liraglutide
eLife 12:e80944.
https://doi.org/10.7554/eLife.80944

Share this article

https://doi.org/10.7554/eLife.80944

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