Porcine glucagon-like peptide-2: Structure, signaling, metabolism and effects

Abstract

Mass spectrometry of HPLC-purified porcine glucagon-like peptide-2 (pGLP-2) 1 1 AcN, Acetonitrile; AUC, Area under the curve; DPP-4, Dipeptidyl peptidase 4; GLP-1, Glucagon-like peptide-1; GLP-2, Glucagon-like peptide-2; GLP-2R, GLP-2 receptor; hGLP-2, human GLP-2; HPLC, High pressure liquid chromatography; IBMX, 3-isobutyl-1-methylxanthine; LYD, Landrace Yorkshire Duroc; LYY, Landrace Yorkshire Yorkshire; MALDI, Matrix-assisted laser desorption/ionization; MCR, Metabolic clearance rate; NCBI, National Center of Biotechnology Information; PBS, Phosphate buffered saline; pGLP-2, porcine GLP-2; RIA, Radioimmunoassay; SEM, Standard error of the mean; TFA, Trifluoroacetic acid; TOF, Time of flight. revealed a 35 amino acid sequence with C-terminal Ser and Leu, in contrast to the 33 amino acids of human, cow, rat and mouse GLP-2. Synthetic pGLP-2 stimulated cAMP-production in COS-7 cells expressing human GLP-2 (hGLP-2) receptor with the same potency and efficacy as hGLP-2. In anesthetized pigs ( n = 9) given intravenous pGLP-2 infusions, the half life ( t1/2) of intact pGLP-2 (8.4 ± 0.9 min) was shorter ( p < 0.01) than that of the primary metabolite pGLP-2 (3–35) (34.0 ± 5.2 min), generated by dipeptidyl peptidase-4 (DPP-4) cleavage. Adding the DPP-4 inhibitor valine-pyrrolidide prolonged t1/2 of intact pGLP-2 ( p < 0.05). The metabolic clearance rate (MCR) of intact pGLP-2 (23.9 ± 3.82 mL/(kg∙min)) was greater ( p < 0.0001) than that of pGLP-2 (3–35) (6.36 ± 1.45 mL/(kg∙min)) and larger than the previously reported MCR of hGLP-2 in pig. The MCR of intact pGLP-2 was reduced by valine-pyrrolidide ( p < 0.05), but was still greater than that of intact hGLP-2 previously reported. In the isolated perfused porcine pancreas, pGLP-2 stimulated glucagon release ( p < 0.05), but had no effect on insulin or somatostatin release. Exocrine secretion was unaffected and there was no apparent vasoactive effect. In mice ( n = 8), both subcutaneous hGLP-2 and pGLP-2 given twice daily for 10 days, significantly and equally increased small intestinal weight, length and cross-sectional area of proximal ileum. In conclusion, pGLP-2 and hGLP-2 have similar effects in vivo and in vitro in spite of the structural differences. However, pGLP-2 is cleared more rapidly in pigs than hGLP-2.