Frontiers in Cell and Developmental Biology (Jan 2023)

The β2-adrenergic receptor in the apical membrane of intestinal enterocytes senses sugars to stimulate glucose uptake from the gut

  • Frederik Paulussen,
  • Frederik Paulussen,
  • Chetan P. Kulkarni,
  • Chetan P. Kulkarni,
  • Frank Stolz,
  • Frank Stolz,
  • Eveline Lescrinier,
  • Stijn De Graeve,
  • Stijn De Graeve,
  • Suzan Lambin,
  • Suzan Lambin,
  • Arnaud Marchand,
  • Patrick Chaltin,
  • Peter In't Veld,
  • Joseph Mebis,
  • Jan Tavernier,
  • Jan Tavernier,
  • Patrick Van Dijck,
  • Patrick Van Dijck,
  • Walter Luyten,
  • Johan M. Thevelein,
  • Johan M. Thevelein,
  • Johan M. Thevelein

DOI
https://doi.org/10.3389/fcell.2022.1041930
Journal volume & issue
Vol. 10

Abstract

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The presence of sugar in the gut causes induction of SGLT1, the sodium/glucose cotransporter in intestinal epithelial cells (enterocytes), and this is accompanied by stimulation of sugar absorption. Sugar sensing was suggested to involve a G-protein coupled receptor and cAMP - protein kinase A signalling, but the sugar receptor has remained unknown. We show strong expression and co-localization with SGLT1 of the β2-adrenergic receptor (β2-AR) at the enterocyte apical membrane and reveal its role in stimulating glucose uptake from the gut by the sodium/glucose-linked transporter, SGLT1. Upon heterologous expression in different reporter systems, the β2-AR responds to multiple sugars in the mM range, consistent with estimated gut sugar levels after a meal. Most adrenergic receptor antagonists inhibit sugar signaling, while some differentially inhibit epinephrine and sugar responses. However, sugars did not inhibit binding of I125-cyanopindolol, a β2-AR antagonist, to the ligand-binding site in cell-free membrane preparations. This suggests different but interdependent binding sites. Glucose uptake into everted sacs from rat intestine was stimulated by epinephrine and sugars in a β2-AR-dependent manner. STD-NMR confirmed direct physical binding of glucose to the β2-AR. Oral administration of glucose with a non-bioavailable β2-AR antagonist lowered the subsequent increase in blood glucose levels, confirming a role for enterocyte apical β2-ARs in stimulating gut glucose uptake, and suggesting enterocyte β2-AR as novel drug target in diabetic and obese patients. Future work will have to reveal how glucose sensing by enterocytes and neuroendocrine cells is connected, and whether β2-ARs mediate glucose sensing also in other tissues.

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