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

Green, BD; Gault, Victor; Mooney, MH; Irwin, Nigel; Bailey, Clifford J.; Harriott, Patrick; Greer, Brett; Flatt, Peter R.; O’Harte, Finbarr

doi:10.1677/jme.0.0310529

Cited by 37 publications

(52 citation statements)

References 51 publications

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“…44 This includes the design and generation of modified DPP-IVresistant GLP-1 peptides with mutations in His 7,26 and Ala 8 residues. 45 However, while some of the GLP-1-derived agonists are evidently DPP-IV resistant, they were purified using protein G Sepharose. Varying amounts of purified protein were used for detection of GLP-1 protein using a total GLP-1 RIA kit.…”

Section: Discussionmentioning

confidence: 99%

Gene therapy of diabetes using a novel GLP-1/IgG1-Fc fusion construct normalizes glucose levels in db/db mice

et al. 2006

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Glucagon-like peptide (GLP-1), a major physiological incretin, plays numerous important roles in modulating blood glucose homeostasis and has been proposed for the treatment of type 2 diabetes. The major obstacles for using native GLP-1 as a therapeutic agent are that it must be delivered by a parenteral route and has a short half-life. In an attempt to develop a strategy to prolong the physiological t 1/2 and enhance the potency of GLP-1, a fusion protein consisting of active human GLP-1 and mouse IgG 1 heavy chain constant regions (GLP-1/Fc) was generated. A plasmid encoding an IgK leader peptide-driven secretable fusion protein of the active GLP-1 and IgG 1 -Fc was constructed for mammalian expression. This plasmid allows for expression of bivalent GLP-1 peptide ligands as a result of IgG-Fc homodimerization. In vitro studies employing purified GLP-1/ Fc indicate that the fusion protein is functional and elevates cAMP levels in insulin-secreting INS-1 cells. In addition, it stimulates insulin secretion in a glucose concentrationdependent manner. Intramuscular gene transfer of the plasmid in db/db mice demonstrated that expression of the GLP-1/Fc peptide normalizes glucose tolerance by enhancing insulin secretion and suppressing glucagon release. This strategy of using a bivalent GLP-1/Fc fusion protein as a therapeutic agent is a novel approach for the treatment of diabetes.

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Section: Discussionmentioning

confidence: 99%

Gene therapy of diabetes using a novel GLP-1/IgG1-Fc fusion construct normalizes glucose levels in db/db mice

et al. 2006

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“…In-vivo they lowered circulating blood glucose and increased blood insulin concentrations in Zucker rats. )GLP-1 were 1.5-and 3.5-fold less potent, respectively, than native GLP-1 (Green et al 2003b). Despite these losses in receptor affinity and cAMP production, this did not compromise insulinotropic activity either in-vitro or in-vivo (Table 2).…”

Section: Position 2 (Ala 8 Substituted) Analogues Of Glp-1mentioning

confidence: 95%

“…This may be partially explained by the diverse mechanisms of action of GLP-1 on the pancreatic -cell. Glucose tolerance tests in obese diabetic (ob/ob) mice showed that (Abu )GLP-1 appeared to be equipotent insulin secretagogues in-vivo (Green et al 2003b). Amino acid substitution of GLP-1 at Ala 8 appears to be a particularly viable strategy for generating worthwhile stable therapeutic candidate peptides for the treatment of type 2 diabetes.…”

Section: Position 2 (Ala 8 Substituted) Analogues Of Glp-1mentioning

confidence: 99%

Targeting β-cell cyclic 3′5′adenosine monophosphate for the development of novel drugs for treating type 2 diabetes mellitus. A review

Furman

Pyne

Flatt³

et al. 2004

Journal of Pharmacy and Pharmacology

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Cyclic 3'5'AMP is an important physiological amplifier of glucose-induced insulin secretion by the pancreatic islet -cell, where it is formed by the activity of adenylyl cyclase, especially in response to the incretin hormones GLP-1 (glucagon-like peptide-1) and GIP (glucose-dependent insulinotropic peptide). These hormones are secreted from the small intestine during and following a meal, and are important in producing a full insulin secretory response to nutrient stimuli. Cyclic AMP influences many steps involved in glucose-induced insulin secretion and may be important in regulating pancreatic islet -cell differentiation, growth and survival. Cyclic AMP (cAMP) itself is rapidly degraded in the pancreatic islet -cell by cyclic nucleotide phosphodiesterase (PDE) enzymes. This review discusses the possibility of targeting cAMP mechanisms in the treatment of type 2 diabetes mellitus, in which insulin release in response to glucose is impaired. This could be achieved by the use of GLP-1 or GIP to elevate cAMP in the pancreatic islet -cell. However, these peptides are normally rapidly degraded by dipeptidyl peptidase IV (DPP IV). Thus longer-acting analogues of GLP-1 and GIP, resistant to enzymic degradation, and orally active inhibitors of DPP IV have also been developed, and these agents were found to improve metabolic control in experimentally diabetic animals and in patients with type 2 diabetes. The use of selective inhibitors of type 3 phosphodiesterase (PDE3B), which is probably the important pancreatic islet -cell PDE isoform, would require their targeting to the islet -cell, because inhibition of PDE3B in adipocytes and hepatocytes would induce insulin resistance.

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“…It makes the GLP-1 to render DPP-IV-resistant and to extend its circulating half-life. 42 The plasmid that contained a leader sequence, an intervening HA tag and a furin-recognition site upstream of the GLP-1 gene produced the greatest amount of GLP-1 and, interestingly, produced more GLP-1 than did a plasmid with a furin site but without an HA tag. Furin is a type of protein convertase that is involved in the conversion of pro-hormones and precursor proteins into biologically active peptides and proteins.…”

Section: Increased Gene Expression In the Liver And Pancreas Of Dsaavmentioning

confidence: 94%

Long-term, antidiabetogenic effects of GLP-1 gene therapy using a double-stranded, adeno-associated viral vector

Choi

Lee

2010

Gene Ther

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Diabetes is characterized by insulin resistance and a reduction in insulin secretion, leading to progressive b-cell failure and loss of b-cell mass. Its central therapeutic issues are how to restore glucose responsiveness of b-cells to normal and counteract defects in insulin secretion. Native glucagon-like peptide-1 (GLP-1), which makes b-cells competent and diabetic b-cells specifically more sensitive to glucose, has a major drawback of rapid inactivation. In this study, we describe the construction and analysis of a GLP-1 plasmid and double-stranded, adeno-associated viral (dsAAV) expression vector to overcome both the rapid degradation of native GLP-1 and limitations of gene therapy using standard single-stranded AAV. Our study results demonstrate that fasting blood glucose levels of db/db obese mice decreased significantly up to 4 months after a single injection of dsAAV GLP-1, and both insulin and circulating GLP-1 levels increased in dsAAV GLP-1-infected mice. These results demonstrate that dsAAV GLP-1 has long-term, efficient transgene expression with minimal toxicity and cellular immune responses. This study suggests that GLP-1 produced by dsAAV may be an alternative to the continuous infusions required for GLP-1 peptide therapy or daily injections of GLP-1. Gene Therapy (2011) (T2D) is a disorder of glucose homeostasis characterized by hyperglycemia, peripheral insulin resistance, impaired hepatic glucose metabolism and diminished glucose-dependent secretion of insulin from pancreatic b-cells. 1 These pathologies result in progressive b-cell failure, resulting in the loss of b-cell mass. 2,3 There is consequently a need for either single hypoglycemic agents or agents that can be combined with insulin surrogate therapy to control blood glucose. From a therapeutic viewpoint, an important issue is how to restore the normal responsiveness of b-cells to glucose so that insulin secretion can occur. The incretin hormone, glucagon-like peptide-1 (GLP-1), has attracted much attention as it can counteract uncontrolled insulin secretion. 4 The 'incretin effect' refers to the amplification of insulin secretion elicited by hormones secreted from the gastrointestinal tract. 5 The pro-glucagon-derived peptide GLP-1 is produced by L cells in the small intestine in response to fat and carbohydrates. GLP-1 makes b-cells competent and sensitizes diabetic b-cells specifically to glucose, thereby restoring normal insulin secretion by its insulinotropic actions on b-cells. These glucose-dependent effects include cAMP formation, insulin secretion, insulin biosynthesis and pro-insulin gene expression. 6,7 GLP-1 also enhances b-cell mass by inhibition of b-cell apoptosis and stimulation of b-cell proliferation in the rodents. 8,9 However, the use and development of GLP-1 as a therapeutic agent in vivo is hampered by its short half-life; this peptide hormone is degraded by dipeptidyl peptidase-4 (DPP-IV, natural inhibitor of GLP-1) and neutral endopeptidase, and is cleared by the kidneys. 10 Because of extensive degradation, pl...

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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

Abstract: 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

Cited by 37 publications

References 51 publications

Gene therapy of diabetes using a novel GLP-1/IgG1-Fc fusion construct normalizes glucose levels in db/db mice

Gene therapy of diabetes using a novel GLP-1/IgG1-Fc fusion construct normalizes glucose levels in db/db mice

Targeting β-cell cyclic 3′5′adenosine monophosphate for the development of novel drugs for treating type 2 diabetes mellitus. A review

Long-term, antidiabetogenic effects of GLP-1 gene therapy using a double-stranded, adeno-associated viral vector

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