Design, synthesis and in vitro characterization of Glucagon-Like Peptide-1 derivatives for pancreatic beta cell imaging by SPECT.
Novel Glucagon-Like Peptide-1 (GLP-1) derivatives containing the metal chelator DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) and naturally occurring Indium ((113/115)In) were prepared using solid-phase Fmoc methods. All synthesized peptides contained d-Ala-8, a modification known to improve resistance towards degradation by dipeptidyl peptidase-IV. The effect of increased distance between DOTA and the peptide chain was investigated using an (aminoethyl) ethoxy acetyl linker, in order to reduce steric effects imposed by DOTA. Placement of linker and DOTA moieties were also varied within the GLP-1 sequence to test for optimal metal-complex location. The binding affinity of the peptide derivatives was determined in vitro with Chinese hamster ovary cells stably transfected with a human GLP-1 receptor (CHO/GLP-1R) cell line and was shown to be in the nM range. Gamma camera imaging of an insulinoma cell line was carried out using (111)In-labeled peptides. Our results suggest that the prepared GLP-1 derivatives are suitable imaging probes for studying pancreatic islet function in vivo.
Behnam Azad
Babak
B
Departments of Chemistry, The University of Western Ontario, 1151 Richmond Street, London, Ontario, Canada.
Rota
Vanessa A
VA
Breadner
Daniel
D
Dhanvantari
Savita
S
Luyt
Leonard G
LG
D000595:Amino Acid Sequence; D000818:Animals; D001667:Binding, Competitive; D016466:CHO Cells; D002460:Cell Line; D006224:Cricetinae; D003412:Cricetulus; D000242:Cyclic AMP / Q000378:metabolism; D005720:Gamma Rays; D052216:Glucagon-Like Peptide 1 / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism; D000067757:Glucagon-Like Peptide-1 Receptor; D006573:Heterocyclic Compounds, 1-Ring / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D007204:Indium / Q000737:chemistry* / Q000378:metabolism; D050417:Insulin-Secreting Cells / Q000166:cytology*; D008969:Molecular Sequence Data; D010949:Plasma / Q000378:metabolism; D011485:Protein Binding; D011859:Radiography / Q000379:methods*; D051381:Rats; D018027:Receptors, Glucagon / Q000378:metabolism
C000593833:GLP1R protein, human; C000593835:Glp1r protein, rat; D000067757:Glucagon-Like Peptide-1 Receptor; D006573:Heterocyclic Compounds, 1-Ring; D018027:Receptors, Glucagon; D007204:Indium; C071349:1,4,7,10-tetraazacyclododecane- 1,4,7,10-tetraacetic acid; D052216:Glucagon-Like Peptide 1; D000242:Cyclic AMP