ABSTRACT
The peptide hormone glucagon-like peptide (GLP)-1 has important actions resulting in glucose lowering along with weight loss in patients with type 2 diabetes. As a peptide hormone, GLP-1 has to be administered by injection. Only a few small-molecule agonists to peptide hormone receptors have been described and none in the B family of the G protein coupled receptors to which the GLP-1 receptor belongs. We have discovered a series of small molecules known as ago-allosteric modulators selective for the human GLP-1 receptor. These compounds act as both allosteric activators of the receptor and independent agonists. Potency of GLP-1 was not changed by the allosteric agonists, but affinity of GLP-1 for the receptor was increased. The most potent compound identified stimulates glucose-dependent insulin release from normal mouse islets but, importantly, not from GLP-1 receptor knockout mice. Also, the compound stimulates insulin release from perfused rat pancreas in a manner additive with GLP-1 itself. These compounds may lead to the identification or design of orally active GLP-1 agonists.
Subject(s)
Quinoxalines/pharmacology , Receptors, Glucagon/agonists , Sulfones/pharmacology , Thiadiazoles/pharmacology , Animals , Cells, Cultured , Cricetinae , Drug Evaluation, Preclinical , Glucagon-Like Peptide-1 Receptor , Glucagon-Like Peptides/chemistry , Glucagon-Like Peptides/metabolism , Humans , Insulin/metabolism , Insulin Secretion , Mice , Mice, Knockout , Molecular Structure , Pancreas/drug effects , Pancreas/metabolism , Pancreas/surgery , Perfusion , Quinoxalines/chemistry , Receptors, Glucagon/genetics , Receptors, Glucagon/metabolism , Sulfones/chemistry , Thiadiazoles/chemistryABSTRACT
Derivatization of insulin with phenylboronic acids is described, thereby equipping insulin with novel glucose sensing ability. It is furthermore demonstrated that such insulins are useful in glucose-responsive polymer-based release systems. The preferred phenylboronic acids are sulfonamide derivatives, which, contrary to naïve boronic acids, ensure glucose binding at physiological pH, and simultaneously operate as handles for insulin derivatization at LysB29. The glucose affinities of the novel insulins were evaluated by glucose titration in a competitive assay with alizarin. The affinities were in the range 15-31 mM (K(d)), which match physiological glucose fluctuations. The dose-responsive glucose-mediated release of the novel insulins was demonstrated using glucamine-derived polyethylene glycol polyacrylamide (PEGA) as a model, and it was shown that Zn(II) hexamer formulation of the boronated insulins resulted in steeper glucose sensitivity relative to monomeric insulin formulation. Notably, two of the boronated insulins displayed enhanced insulin receptor affinity relative to native insulin (113%-122%) which is unusual for insulin LysB29 derivatives.
Subject(s)
Biosensing Techniques , Glucose/pharmacology , Insulin/analogs & derivatives , Insulin/chemistry , Insulin/metabolism , Amino Acid Sequence , Humans , Indicators and Reagents , Insulin/chemical synthesis , Insulin Secretion , Molecular Sequence Data , Peptides, Cyclic/chemical synthesis , Peptides, Cyclic/chemistry , Receptor, Insulin/genetics , Receptor, Insulin/metabolism , Sequence DeletionABSTRACT
A novel class of GSK-3 inhibitors with favorable water solubility was identified in a HTS screen. SAR studies identified bioisosteric structural moieties in this class of compounds. The compounds were tested in a GSK-3 inhibition assay at 100 microM ATP giving IC(50)'s in the range from 0.1 to 10 microM. The compounds are ATP competitive inhibitors. They modulate glycogen metabolism and stimulate the accumulation of intracellular beta-catenin in whole cell assays with EC(50)'s in the range from 2 to 18 microM and 4.5-44 microM, respectively. For selected compounds, only a 10-fold lower potency was obtained in cellular assays compared to the potency obtained for inhibition of the isolated enzyme, reflecting a good cell permeability of this compound class. At 10 microM of test compound a 3-fold stimulation of the glycogen synthesis in rat soleus muscle was obtained compared to the level of glycogen synthesis observed at 0.2 nM insulin. This stimulation of glycogen synthesis is comparable to the maximal stimulation by insulin itself.
Subject(s)
Enzyme Inhibitors/chemical synthesis , Glycogen Synthase Kinase 3/antagonists & inhibitors , Oxadiazoles/chemical synthesis , Triazoles/chemical synthesis , Animals , CHO Cells , Cricetinae , Cytoskeletal Proteins/metabolism , Databases, Factual , Enzyme Inhibitors/chemistry , Enzyme Inhibitors/pharmacology , Glycogen/biosynthesis , Humans , In Vitro Techniques , Male , Muscle, Skeletal/drug effects , Muscle, Skeletal/metabolism , Oxadiazoles/chemistry , Oxadiazoles/pharmacology , Rats , Rats, Wistar , Solubility , Structure-Activity Relationship , Trans-Activators/metabolism , Triazoles/chemistry , Triazoles/pharmacology , Water , beta CateninABSTRACT
Using a virtual screening strategy based on a methodology derived from the CATS molecular descriptor, a novel compound class with inhibitory activity against the GSK-3 enzyme was identified through scaffold hopping. These compounds were readily synthesized, either by solid-phase or solution-phase chemistry. Compounds with inhibitory activity below 1 microM were identified.
