ABSTRACT
Type 2 diabetes (T2D) is caused by loss of pancreatic ß-cell mass and failure of the remaining ß-cells to deliver sufficient insulin to meet demand. ß-Cell glucolipotoxicity (GLT), which refers to combined, deleterious effects of elevated glucose and fatty acid levels on ß-cell function and survival, contributes to T2D-associated ß-cell failure. Drugs and mechanisms that protect ß-cells from GLT stress could potentially improve metabolic control in patients with T2D. In a phenotypic screen seeking low-molecular-weight compounds that protected ß-cells from GLT, we identified compound A that selectively blocked GLT-induced apoptosis in rat insulinoma cells. Compound A and its optimized analogs also improved viability and function in primary rat and human islets under GLT. We discovered that compound A analogs decreased GLT-induced cytosolic calcium influx in islet cells, and all measured ß-cell-protective effects correlated with this activity. Further studies revealed that the active compound from this series largely reversed GLT-induced global transcriptional changes. Our results suggest that taming cytosolic calcium overload in pancreatic islets can improve ß-cell survival and function under GLT stress and thus could be an effective strategy for T2D treatment.
Subject(s)
Calcium Channels, L-Type/metabolism , Calcium/toxicity , Glycolipids/antagonists & inhibitors , Glycolipids/toxicity , Insulin-Secreting Cells/drug effects , Animals , Apoptosis , Cell Line , Cell Survival , Heterocyclic Compounds/chemistry , Heterocyclic Compounds/pharmacology , Humans , Molecular Structure , Rats , Rats, Sprague-Dawley , TranscriptomeABSTRACT
The relaxin family peptide receptors have been implicated in numerous physiological processes including energy homeostasis, cardiac function, wound healing, and reproductive function. Two family members, RXFP3 and RXFP4, are class A GPCRs with endogenous peptide ligands (relaxin-3 and insulin-like peptide 5 (INSL5), respectively). Polymorphisms in relaxin-3 and RXFP3 have been associated with obesity, diabetes, and hypercholesterolemia. Moreover, central administration of relaxin-3 in rats has been shown to increase food intake, leading to body weight gain. Reported RXFP3 and RXFP4 ligands have been restricted to peptides (both endogenous and synthetic) as well as a low molecular weight positive allosteric modulator requiring a non-endogenous orthosteric ligand. Described here is the discovery of the first potent low molecular weight dual agonists of RXFP3/4. The scaffold identified is competitive with a chimeric relaxin-3/INSL5 peptide for RXFP3 binding, elicits similar downstream signaling as relaxin-3, and increases food intake in rats following acute central administration. This is the first report of small molecule RXFP3/4 agonism.
Subject(s)
Eating/drug effects , Receptors, G-Protein-Coupled/agonists , Small Molecule Libraries/chemistry , Animals , CHO Cells , Cricetinae , Cricetulus , Cyclic AMP/metabolism , Drug Discovery , Ligands , Peptides/chemistry , Peptides/pharmacology , Rats , Receptors, G-Protein-Coupled/genetics , Receptors, G-Protein-Coupled/metabolism , Receptors, Peptide/agonists , Receptors, Peptide/genetics , Receptors, Peptide/metabolism , Relaxin/pharmacology , Small Molecule Libraries/pharmacologyABSTRACT
New N-functionalized benziodazoles were prepared by the peracetic oxidation of 2-iodobenzamides derived from alanine or valine. X-ray crystal structural analysis of two benziodazole-based phenyliodonium derivatives provides insight into facile interchange between benziodazoles and iminium benziodoxoles under acidic or basic conditions. [reaction: see text]