Novel dipeptidyl peptidase IV resistant analogues of glucagon-like peptide-1(7-36)amide have preserved biological activities in vitro conferring improved glucose-lowering action in vivo.
Although the incretin hormone glucagon-like peptide-1 (GLP-1) is a potent stimulator of insulin release, its rapid degradation in vivo by the enzyme dipeptidyl peptidase IV (DPP IV) greatly limits its potential for treatment of type 2 diabetes. Here, we report two novel Ala(8)-substituted analogues of GLP-1, (Abu(8))GLP-1 and (Val(8))GLP-1 which were completely resistant to inactivation by DPP IV or human plasma. (Abu(8))GLP-1 and (Val(8))GLP-1 exhibited moderate affinities (IC(50): 4.76 and 81.1 nM, respectively) for the human GLP-1 receptor compared with native GLP-1 (IC(50): 0.37 nM). (Abu(8))GLP-1 and (Val(8))GLP-1 dose-dependently stimulated cAMP in insulin-secreting BRIN BD11 cells with reduced potency compared with native GLP-1 (1.5- and 3.5-fold, respectively). Consistent with other mechanisms of action, the analogues showed similar, or in the case of (Val(8))GLP-1 slightly impaired insulin releasing activity in BRIN BD11 cells. Using adult obese (ob/ob) mice, (Abu(8))GLP-1 had similar glucose-lowering potency to native GLP-1 whereas the action of (Val(8))GLP-1 was enhanced by 37%. The in vivo insulin-releasing activities were similar. These data indicate that substitution of Ala(8) in GLP-1 with Abu or Val confers resistance to DPP IV inactivation and that (Val(8))GLP-1 is a particularly potent N-terminally modified GLP-1 analogue of possible use in type 2 diabetes.
Green
B D
BD
School of Biomedical Sciences, University of Ulster, Coleraine BT52 1SA, Northern Ireland, UK. b.green@ulster.ac.uk
Gault
V A
VA
Mooney
M H
MH
Irwin
N
N
Bailey
C J
CJ
Harriott
P
P
Greer
B
B
Flatt
P R
PR
O'Harte
F P M
FP
D019943:Amino Acid Substitution / Q000235:genetics*; D000818:Animals; D002478:Cells, Cultured; D006224:Cricetinae; D000242:Cyclic AMP / Q000378:metabolism; D003924:Diabetes Mellitus, Type 2 / Q000378:metabolism*; D018819:Dipeptidyl Peptidase 4 / Q000378:metabolism*; D004798:Enzymes / Q000097:blood; D005934:Glucagon; D052216:Glucagon-Like Peptide 1; D000067757:Glucagon-Like Peptide-1 Receptor; D004763:Glucagon-Like Peptides; D007328:Insulin / Q000378:metabolism; D000078790:Insulin Secretion; D051379:Mice; D008820:Mice, Obese; D010446:Peptide Fragments / Q000032:analysis / Q000378:metabolism*; D018027:Receptors, Glucagon / Q000378:metabolism*; D021241:Spectrometry, Mass, Electrospray Ionization
D004798:Enzymes; C000593833:GLP1R protein, human; C000593834:Glp1r protein, mouse; D000067757:Glucagon-Like Peptide-1 Receptor; D007328:Insulin; D010446:Peptide Fragments; D018027:Receptors, Glucagon; C055453:glucagon-like peptide 1 (7-36)amide; D004763:Glucagon-Like Peptides; D052216:Glucagon-Like Peptide 1; D005934:Glucagon; D000242:Cyclic AMP; D018819:Dipeptidyl Peptidase 4