eLife (Dec 2023)

Phosphorylation bar-coding of free fatty acid receptor 2 is generated in a tissue-specific manner

  • Natasja Barki,
  • Laura Jenkins,
  • Sara Marsango,
  • Domonkos Dedeo,
  • Daniele Bolognini,
  • Louis Dwomoh,
  • Aisha M Abdelmalik,
  • Margaret Nilsen,
  • Manon Stoffels,
  • Falko Nagel,
  • Stefan Schulz,
  • Andrew B Tobin,
  • Graeme Milligan

DOI
https://doi.org/10.7554/eLife.91861
Journal volume & issue
Vol. 12

Abstract

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Free fatty acid receptor 2 (FFAR2) is activated by short-chain fatty acids and expressed widely, including in white adipocytes and various immune and enteroendocrine cells. Using both wild-type human FFAR2 and a designer receptor exclusively activated by designer drug (DREADD) variant we explored the activation and phosphorylation profile of the receptor, both in heterologous cell lines and in tissues from transgenic knock-in mouse lines expressing either human FFAR2 or the FFAR2-DREADD. FFAR2 phospho-site-specific antisera targeting either pSer296/pSer297 or pThr306/pThr310 provided sensitive biomarkers of both constitutive and agonist-mediated phosphorylation as well as an effective means to visualise agonist-activated receptors in situ. In white adipose tissue, phosphorylation of residues Ser296/Ser297 was enhanced upon agonist activation whilst Thr306/Thr310 did not become phosphorylated. By contrast, in immune cells from Peyer’s patches Thr306/Thr310 become phosphorylated in a strictly agonist-dependent fashion whilst in enteroendocrine cells of the colon both Ser296/Ser297 and Thr306/Thr310 were poorly phosphorylated. The concept of phosphorylation bar-coding has centred to date on the potential for different agonists to promote distinct receptor phosphorylation patterns. Here, we demonstrate that this occurs for the same agonist-receptor pairing in different patho-physiologically relevant target tissues. This may underpin why a single G protein-coupled receptor can generate different functional outcomes in a tissue-specific manner.

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