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Novel agonist and antagonist radioligands for the GLP‐2 receptor. Useful tools for studies of basic GLP‐2 receptor pharmacology
Author(s) -
Gadgaard Sarina,
Velden Wijnand J. C.,
Schiellerup Sine P.,
Hunt Jenna Elizabeth,
Gabe Maria B. N.,
Windeløv Johanne Agerlin,
Boer Geke Aline,
Kissow Hannelouise,
Ørskov Cathrine,
Holst Jens J.,
Hartmann Bolette,
Rosenkilde Mette M.
Publication year - 2022
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/bph.15766
Subject(s) - receptor , agonist , chemistry , medicine , endocrinology , biology , biochemistry
Background Glucagon‐like peptide‐2 (GLP‐2) is a pro‐glucagon‐derived hormone secreted from intestinal enteroendocrine L cells with actions on gut and bones. GLP‐2(1–33) is cleaved by DPP‐4, forming GLP‐2(3–33), having low intrinsic activity and competitive antagonism properties at GLP‐2 receptors. We created radioligands based on these two molecules. Experimental approach The methionine in position 10 of GLP‐2(1–33) and GLP‐2(3–33) was substituted with tyrosine (M10Y) enabling oxidative iodination, creating [ 125 I]‐hGLP‐2(1–33,M10Y) and [ 125 I]‐hGLP‐2(3–33,M10Y). Both were characterized by competition binding, on‐and‐off‐rate determination and receptor activation. Receptor expression was determined by target‐tissue autoradiography and immunohistochemistry. Key results Both M10Y‐substituted peptides induced cAMP production via the GLP‐2 receptor comparable to the wildtype peptides. GLP‐2(3–33,M10Y) maintained the antagonistic properties of GLP‐2(3–33). However, hGLP‐2(1–33,M10Y) had lower arrestin recruitment than hGLP‐2(1–33). High affinities for the hGLP‐2 receptor were observed using [ 125 I]‐hGLP‐2(1–33,M10Y) and [ 125 I]‐hGLP‐2(3–33,M10Y) with K D values of 59.3 and 40.6 nM. The latter (with antagonistic properties) had higher B max and faster on and off rates compared to the former (full agonist). Both bound the hGLP‐1 receptor with low affinity ( K i of 130 and 330 nM, respectively). Autoradiography in wildtype mice revealed strong labelling of subepithelial myofibroblasts, confirmed by immunohistochemistry using a GLP‐2 receptor specific antibody that in turn was confirmed in GLP‐2 receptor knock‐out mice. Conclusion and implications Two new radioligands with different binding kinetics, one a full agonist and the other a weak partial agonist with antagonistic properties were developed and subepithelial myofibroblasts identified as a major site for GLP‐2 receptor expression.