Click here to close
Hello! We notice that you are using Internet Explorer, which is not supported by Xenbase and may cause the site to display incorrectly.
We suggest using a current version of Chrome,
FireFox, or Safari.
???displayArticle.abstract???
BACKGROUND: Glucagon-like peptide-1 (GLP-1) is an incretin hormone produced by cleavage of proglucagon in intestinal L-cells. In the pancreas, GLP-1 stimulates post-prandial insulin secretion, promotes insulin biosynthesis, and improves insulin sensitivity. Because of its insulinotropic activity, GLP-1 has been considered a good candidate drug for treatment of diabetes mellitus. However, clinical use of GLP-1 has been limited by its short half-life, as a result of rapid degradation by dipeptidyl peptidase-IV (DPP-IV).
METHODS: We designed a novel GLP-1 analog, Xenopus GLP-1 (xGLP)-E4. The Ala residue in the second position of xGLP was replaced with a Ser residue to increase the half-life in the body. The C-terminal tail of exendin-4 was added to enhance the binding affinity for the GLP-1 receptor (GLP1R). The potency of GLP-1 and its analogs was determined by luciferase assay. The stability of GLP1R agonists was evaluated by determining the activity of agonists that had been preincubated in the presence of fetal bovine serum, which contains innate DPP-IV activity. The effects of xGLP-E4 on insulin secretion and β-cell growth were investigated using insulin enzyme-linked immunosorbent assay and cell counting.
RESULTS: xGLP-E4 exhibited improved stability against DPP-IV activity and increased potency to GLP1R, compared with GLP-1. An increase in glucose-dependent insulin secretion was observed in xGLP-E4-treated pancreatic β-cells. The effect of xGLP-E4 on β-cell growth was greater than that of GLP-1.
CONCLUSION: We developed a novel GLP-1 analog, xGLP-E4, that shows prolonged longevity and improved efficacy. This analog is a potential candidate for treatment of type 2 diabetes.
Fig. 1. Potency of glucagon-like peptide-1 (GLP-1) analogs toward GLP-1 receptor (GLP1R). Ligand potencies of GLP-1 analogs were examined using HEK293T cells expressing GLP1R. Cells were treated with increasing concentrations of GLP-1 analogs for 6 hours, and luciferase activity was measured. The data on the sigmoidal curves and EC50 values are presented as means±standard error of the mean of at least three independent experiments. CRE-luc, cAMP response element-luciferase; xGLP, Xenopus GLP-1.
Fig. 2. Stability of glucagon-like peptide-1 (GLP-1) analogs. The stability of GLP-1 and GLP-1 analogs against dipeptidyl peptidase-IV (DPP-IV) activity was evaluated by incubating the individual peptides in medium containing 10% fetal bovine serum (FBS) (A) or in 100% FBS (B). Peptides were incubated at an initial concentration of 100 nM in Dulbecco's Modified Eagle's medium containing 10% FBS or 100% FBS at 37â in the presence or absence of 0.2 mM of the peptidase inhibitor diprotin A. Peptide activity was then assessed by measuring luciferase activity in cells expressing GLP1R and CRE-luc. Results are presented as mean±standard error of the mean of at least three independent experiments.
Fig. 3. Induction of glucose-dependent insulin secretion by (xGLP-E4). (A) INS-1 cells and (B) β-TC-6 cells were cultured in 24-well plates until 90% confluence. Cells were washed and incubated in Krebs-Ringer Bicarbonate (KRB) buffer and treated with glucose for 2 hours at 37â. Cells were incubated with 10 nM glucagon-like peptide-1 (GLP-1) analog in KRB buffer containing low and high glucose for another 2 hours, and insulin secretion into the buffer was then determined. CTL, control; GLP-1, glucagon-like peptide-1; Exe-4, exendin-4; xGLP, Xenopus GLP-1.
Fig. 4. Induction of β-cell growth by (xGLP-E4). INS-1 cells were seeded in 12-well plates at a density of 4Ã104 cells/well. Every 2 days, the respective peptides were added to the cultures in fresh medium containing the appropriate concentration of glucose. (A) Six and (B) 10 days after cell seeding, cells were washed, harvested, and counted. Results are presented as mean±standard error of the mean of at least three independent experiments. GLP-1, glucagon-like peptide-1; Exe-4, exendin-4; xGLP, Xenopus GLP-1. a vs. control (CTL) (P<0.05); b vs. CTL (P<0.001).
Adelhorst,
Structure-activity studies of glucagon-like peptide-1.
1994, Pubmed
Adelhorst,
Structure-activity studies of glucagon-like peptide-1.
1994,
Pubmed
Ahrén,
Inhibition of dipeptidyl peptidase IV improves metabolic control over a 4-week study period in type 2 diabetes.
2002,
Pubmed
Al-Sabah,
A model for receptor-peptide binding at the glucagon-like peptide-1 (GLP-1) receptor through the analysis of truncated ligands and receptors.
2003,
Pubmed
Baggio,
Harnessing the therapeutic potential of glucagon-like peptide-1: a critical review.
2002,
Pubmed
Baggio,
Lymphocytic infiltration and immune activation in metallothionein promoter-exendin-4 (MT-Exendin) transgenic mice.
2006,
Pubmed
Burcelin,
Long-lasting antidiabetic effect of a dipeptidyl peptidase IV-resistant analog of glucagon-like peptide-1.
1999,
Pubmed
Buse,
Effects of exenatide (exendin-4) on glycemic control over 30 weeks in sulfonylurea-treated patients with type 2 diabetes.
2004,
Pubmed
Chen,
Biochemical properties of recombinant prolyl dipeptidases DPP-IV and DPP8.
2006,
Pubmed
Deacon,
Both subcutaneously and intravenously administered glucagon-like peptide I are rapidly degraded from the NH2-terminus in type II diabetic patients and in healthy subjects.
1995,
Pubmed
Drucker,
Minireview: the glucagon-like peptides.
2001,
Pubmed
Drucker,
Glucagon-like peptides: regulators of cell proliferation, differentiation, and apoptosis.
2003,
Pubmed
Edwards,
Exendin-4 reduces fasting and postprandial glucose and decreases energy intake in healthy volunteers.
2001,
Pubmed
Fehmann,
Insulinotropic hormone glucagon-like peptide-I(7-37) stimulation of proinsulin gene expression and proinsulin biosynthesis in insulinoma beta TC-1 cells.
1992,
Pubmed
Fehmann,
Cell and molecular biology of the incretin hormones glucagon-like peptide-I and glucose-dependent insulin releasing polypeptide.
1995,
Pubmed
Gallwitz,
GLP-1-analogues resistant to degradation by dipeptidyl-peptidase IV in vitro.
2000,
Pubmed
Göke,
Exendin-4 is a high potency agonist and truncated exendin-(9-39)-amide an antagonist at the glucagon-like peptide 1-(7-36)-amide receptor of insulin-secreting beta-cells.
1993,
Pubmed
Gossrau,
[Peptidases II. Localization of dipeptidylpeptidase IV (DPP IV). Histochemical and biochemical study].
1979,
Pubmed
Graziano,
Cloning and functional expression of a human glucagon-like peptide-1 receptor.
1993,
Pubmed
Holst,
Inhibition of the activity of dipeptidyl-peptidase IV as a treatment for type 2 diabetes.
1998,
Pubmed
Hwang,
Expansion of secretin-like G protein-coupled receptors and their peptide ligands via local duplications before and after two rounds of whole-genome duplication.
2013,
Pubmed
Irwin,
The Xenopus proglucagon gene encodes novel GLP-1-like peptides with insulinotropic properties.
1997,
Pubmed
,
Xenbase
Kaung,
Effect of glucose on beta cell proliferation and population size in organ culture of foetal and neonatal rat pancreases.
1983,
Pubmed
Kendall,
Effects of exenatide (exendin-4) on glycemic control over 30 weeks in patients with type 2 diabetes treated with metformin and a sulfonylurea.
2005,
Pubmed
Kieffer,
Degradation of glucose-dependent insulinotropic polypeptide and truncated glucagon-like peptide 1 in vitro and in vivo by dipeptidyl peptidase IV.
1995,
Pubmed
Mentlein,
Dipeptidyl-peptidase IV hydrolyses gastric inhibitory polypeptide, glucagon-like peptide-1(7-36)amide, peptide histidine methionine and is responsible for their degradation in human serum.
1993,
Pubmed
Moon,
Tyr1 and Ile7 of glucose-dependent insulinotropic polypeptide (GIP) confer differential ligand selectivity toward GIP and glucagon-like peptide-1 receptors.
2010,
Pubmed
Moon,
Evolutionarily conserved residues at glucagon-like peptide-1 (GLP-1) receptor core confer ligand-induced receptor activation.
2012,
Pubmed
Moon,
Structural and molecular conservation of glucagon-like Peptide-1 and its receptor confers selective ligand-receptor interaction.
2012,
Pubmed
Moore,
On the treatment of Diabetus mellitus by acid extract of Duodenal Mucous Membrane.
1906,
Pubmed
Nauck,
Effects of glucagon-like peptide 1 on counterregulatory hormone responses, cognitive functions, and insulin secretion during hyperinsulinemic, stepped hypoglycemic clamp experiments in healthy volunteers.
2002,
Pubmed
Nauck,
Influence of glucagon-like peptide 1 on fasting glycemia in type 2 diabetic patients treated with insulin after sulfonylurea secondary failure.
1998,
Pubmed
Nauck,
Glucagon-like peptide 1 inhibition of gastric emptying outweighs its insulinotropic effects in healthy humans.
1997,
Pubmed
Orskov,
Glucagon-like peptides GLP-1 and GLP-2, predicted products of the glucagon gene, are secreted separately from pig small intestine but not pancreas.
1986,
Pubmed
Park,
A novel glucagon-related peptide (GCRP) and its receptor GCRPR account for coevolution of their family members in vertebrates.
2013,
Pubmed
,
Xenbase
Pauly,
Improved glucose tolerance in rats treated with the dipeptidyl peptidase IV (CD26) inhibitor Ile-thiazolidide.
1999,
Pubmed
Perfetti,
Glucagon-like peptide-1: a major regulator of pancreatic beta-cell function.
2000,
Pubmed
Perfetti,
Glucagon-like peptide-1 induces cell proliferation and pancreatic-duodenum homeobox-1 expression and increases endocrine cell mass in the pancreas of old, glucose-intolerant rats.
2000,
Pubmed
Shen,
The effect of glucose and glucagon-like peptide-1 stimulation on insulin release in the perfused pancreas in a non-insulin-dependent diabetes mellitus animal model.
1998,
Pubmed
Underwood,
Crystal structure of glucagon-like peptide-1 in complex with the extracellular domain of the glucagon-like peptide-1 receptor.
2010,
Pubmed
