Identification of Betulinic Acid Derivatives as Potent TGR5 Agonists with Antidiabetic Effects via Humanized TGR5^H88Y Mutant Mice

Takeda
G protein-coupled receptor 5 (TGR5) is a promising target
for treating metabolic syndrome and inflammatory diseases. Herein,
we identified a new series of betulinic acid derivatives as potent
TGR5 agonists, which show remarkable activity on human (h) and canine
(c) TGR5 but exhibit unpromising activity on murine (m) TGR5. Species
difference was also observed with many other reported TGR5 agonists.
Therefore, we screened 29 amino acids which were conserved in hTGR5
and cTGR5 but different in mTGR5 and found a key amino acid, H88 in
mTGR5 (Y89 in hTGR5), which contributed to the species difference.
With the CRISPR/Cas9 system, the mTGR5H88Y mutation was
introduced into mice, and the optimized compound 11d-Na displayed a significant glucose-lowering effect and stimulated GLP-1
and insulin secretion in TGR5H88Y mice but not in wild-type
animals. Taken together, our study provides a useful tool to bridge
the gap of species difference and discovers a potent TGR5 agonist
for further investigation.