G Protein-Coupled Receptor 119 (GPR119) Agonists for the Treatment of Diabetes: Recent Progress and Prevailing Challenges

GPR119 agonist enhances gefitinib responsiveness through lactate-mediated inhibition of autophagy

Background

Ligand-dependent activation of the G-protein coupled receptor 119 (GPR119) lowers blood glucose via glucose-dependent insulin secretion and intestinal glucagon-like peptide-1 production. However, the function of GPR119 in cancer cells has not been studied.

Methods

GPR119 expression was assessed by real-time qPCR and immunohistochemistry in human breast cancer cell lines and breast cancer tissues. Cell proliferation and cell cycle analyses were performed by Incucyte® live cell analysis system and flow cutometry, respectively. Autophagy activity was estimeated by western blottings and LC3-GFP transfection.

Results

mRNA or protein expression of GPR119 was detected in 9 cancer cell lines and 19 tissue samples. Cotreatment with GPR119 agonist (MBX-2982 or GSK1292263) significantly potentiated gefitinib-induced cell growth inhibition in gefitinib-insensitive MCF-7 and MDA-MB-231 breast cancer cells. We observed that caspase-3/7 activity was enhanced with the downregulation of Bcl-2 in MCF-7 cells exposed to MBX-2982. Gefitinib-induced autophagy is related with cancer cell survival and chemoresistance. GPR119 agonists inhibit gefitinib-induced autophagosome formation in MCF-7 and MDA-MB-231 cells. MBX-2982 also caused a metabolic shift to enhanced glycolysis accompanied by reduced mitochondrial oxidative phosphorylation. MBX-2982 increased intracellular (~ 2.5 mM) and extracellular lactate (~ 20 mM) content. Gefitinib-mediated autophagy was suppressed by 20 mM lactate in MCF-7 cells.

Conclusions

GPR119 agonists reduced mitochondrial OXPHOS and stimulated glycolysis in breast cancer cells, with consequent overproduction of lactate that inhibited autophagosome formation. Because autophagy is crucial for the survival of cancer cells exposed to TKIs, GPR119 agonists potentiated the anticancer effects of TKIs.

Electronic supplementary material

The online version of this article (10.1186/s13046-018-0949-2) contains supplementary material, which is available to authorized users.

DS-8500a, an Orally Available G Protein-Coupled Receptor 119 Agonist, Upregulates Glucagon-Like Peptide-1 and Enhances Glucose-Dependent Insulin Secretion and Improves Glucose Homeostasis in Type 2 Diabetic Rats

G protein-coupled receptor 119 (GPR119) has been shown to be highly expressed in small intestinal L-cells and pancreatic β-cells and mediates intracellular cAMP concentration, glucagon-like peptide (GLP-1) secretion, and glucose-stimulated insulin secretion (GSIS). This study examined the pharmacological effects of 4-(5-{(1R)-1-[4-(cyclopropylcarbonyl) phenoxy]propyl}-1,2,4-oxadiazol-3-yl)-2-fluoro-N-[(2R)-1-hydroxypropan-2-yl]benzamide (DS-8500a), a novel, orally available, selective GPR119 agonist. In in vitro studies, DS-8500a increased intracellular cAMP in a concentration-dependent manner in human, rat, and mouse GPR119-expressing Chinese hamster ovary (CHO)-K1 cells, with EC₅₀ values of 51.5, 98.4, and 108.1 nmol/l, respectively. DS-8500a had no effect on intracellular cAMP in pcDNA3.1/CHO-K1 cells. In in vivo studies, DS-8500a augmented plasma GLP-1 concentration in Zucker fatty (ZF) rats, and enhanced GSIS and did not change plasma glucose concentration in fasted Sprague-Dawley (SD) rats. A single dose of DS-8500a showed dose-dependent glucose-lowering effects at oral glucose tolerance test (OGTT) in ZF rats. In a repeat-dosing study, DS-8500a had statistically significant glucose-lowering effects at OGTT performed at the 1st day and after 2 weeks of treatment in neonatal streptozotocin-treated (nSTZ) rats, and the efficacy levels of DS-8500a in each test were greater than those of GSK1292263 or MBX-2982, which had been clinically tested previously as GPR119 agonists. Through pharmacokinetics and pharmacodynamics assessment, the high intrinsic activity of DS-8500a was suggested to be one of the reasons for the greater glucose lowering effect in the nSTZ rats. DS-8500a is a useful compound among GPR119 agonists that can maximize the potential benefit of GPR119 in type 2 diabetes.

Design, synthesis, and biological evaluation of 2-(4-(methylsulfonyl)phenyl)pyridine derivatives as GPR119 agonists

This study describes the design, synthesis, and biological evaluation of a series of novel small molecule GPR119 agonists with improved potency and moderate physiochemical characteristics. Among them, the most promising compounds 19 and 20 were obtained with EC₅₀ values of 75 and 25 nM, respectively, in vitro cAMP assays and effectively decreased blood glucose excursion in oral glucose tolerance test (OGTT) of normal mice. Furthermore, in OGTT with type 2 diabetic mice induced by streptozotocin and high-fat diet, compound 19 also showed significant reduction in blood glucose level compared to vehicle control group, which demonstrated an attractive in vitro and in vivo profile for further development.

Pharmacokinetics and Safety of DS-8500a, an Antidiabetic Drug, in Japanese Subjects with Hepatic or Renal Impairment: A Single-Center, Open-Label, Single-Dose Study

INTRODUCTION

The pharmacokinetics, safety, and tolerability of DS-8500a (a G protein receptor 119 agonist) up to 100 mg have been investigated in healthy Japanese adults. The objective of this study was to evaluate the effects of hepatic or renal impairment on the pharmacokinetics of a single 25-mg oral dose of DS-8500a.

METHODS

This single-center, open-label study enrolled subjects into eight groups according to hepatic function (normal; mild or moderate impairment) and renal function [normal; mild, moderate, or severe impairment; and end-stage renal disease (ESRD)]. Drug concentrations were measured by liquid-chromatography tandem mass spectrometry. Pharmacokinetic parameters were evaluated by non-compartmental analysis. Adverse events (AEs) were evaluated for safety.

RESULTS

The hepatic and renal groups enrolled 15 and 30 subjects, respectively. Pharmacokinetic parameters of DS-8500a were comparable between the normal hepatic function and mild hepatic impairment groups, but the mean area under the concentration-time curve (AUC) was 1.37-fold higher, and the half-life was longer in the moderate hepatic impairment group compared with the normal hepatic function group. The maximum concentration (C_max) and AUC values were 0.704- and 0.609-fold lower, respectively, in the ESRD group compared with the values in the other renal impairment groups; no clear differences in AUC and time to C_max were observed in the normal function and mild, moderate, and severe renal impairment groups. There was no relationship between apparent total body clearance and estimated glomerular filtration rate. The incidence of AEs was similar among all groups.

CONCLUSION

DS-8500a exposure in the mild hepatic impairment and mild to severe renal impairment groups was similar to that in the corresponding normal hepatic and renal function groups, but dose adjustments may be required in those with moderate hepatic impairment and ESRD.

TRIAL REGISTRATION

Japic CTI-No. 163135.

FUNDING

Daiichi Sankyo Co. Ltd., Tokyo, Japan.

GPR119 Agonism Increases Glucagon Secretion During Insulin-Induced Hypoglycemia

Insulin-induced hypoglycemia in diabetes is associated with impaired glucagon secretion. In this study, we tested whether stimulation of GPR119, a G-protein-coupled receptor expressed in pancreatic islet as well as enteroendocrine cells and previously shown to stimulate insulin and incretin secretion, might enhance glucagon secretion during hypoglycemia. In the study, GPR119 agonists were applied to isolated islets or perfused pancreata to assess insulin and glucagon secretion during hypoglycemic or hyperglycemic conditions. Insulin infusion hypoglycemic clamps were performed with or without GPR119 agonist pretreatment to assess glucagon counterregulation in healthy and streptozotocin (STZ)-induced diabetic rats, including those exposed to recurrent bouts of insulin-induced hypoglycemia that leads to suppression of hypoglycemia-induced glucagon release. Hypoglycemic clamp studies were also conducted in GPR119 knockout (KO) mice to evaluate whether the pharmacological stimulatory actions of GPR119 agonists on glucagon secretion during hypoglycemia were an on-target effect. The results revealed that GPR119 agonist-treated pancreata or cultured islets had increased glucagon secretion during low glucose perfusion. In vivo, GPR119 agonists also significantly increased glucagon secretion during hypoglycemia in healthy and STZ-diabetic rats, a response that was absent in GPR119 KO mice. In addition, impaired glucagon counterregulatory responses were restored by a GPR119 agonist in STZ-diabetic rats that were exposed to antecedent bouts of hypoglycemia. Thus, GPR119 agonists have the ability to pharmacologically augment glucagon secretion, specifically in response to hypoglycemia in diabetic rodents. Whether this effect might serve to diminish the occurrence and severity of iatrogenic hypoglycemia during intensive insulin therapy in patients with diabetes remains to be established.

Discovery of MK-8282 as a Potent G-Protein-Coupled Receptor 119 Agonist for the Treatment of Type 2 Diabetes

The ever-growing prevalence of type 2 diabetes in the world has necessitated an urgent need for multiple orally effective agents that can regulate glucose homeostasis with a concurrent reduction in body weight. G-Protein coupled receptor 119 (GPR119) is a GPCR target at which agonists have demonstrated glucose-dependent insulin secretion and shows beneficial effects on glycemic control. Herein, we describe our efforts leading to the identification of a potent, oral GPR-119 agonist, MK-8282, which shows improved glucose tolerance in multiple animal models and has excellent off-target profile. The key design elements in the compounds involved a combination of a fluoro-pyrimidine and a conformationally constrained bridged piperidine to impart good potency and efficacy.

Bidirectional GPR119 Agonism Requires Peptide YY and Glucose for Activity in Mouse and Human Colon Mucosa

The lipid sensor G protein-coupled receptor 119 (GPR119) is highly expressed by enteroendocrine L-cells and pancreatic β-cells that release the hormones, peptide YY (PYY) and glucagonlike peptide 1, and insulin, respectively. Endogenous oleoylethanolamide (OEA) and the dietary metabolite, 2-monoacylglycerol (2-OG), can each activate GPR119. Here, we compared mucosal responses with selective, synthetic GPR119 agonists (AR440006 and AR231453) and the lipids, OEA, 2-OG, and N-oleoyldopamine (OLDA), monitoring epithelial ion transport as a readout for L-cell activity in native mouse and human gastrointestinal (GI) mucosae. We also assessed GPR119 modulation of colonic motility in wild-type (WT), GPR119-deficient (GPR119-/-), and PYY-deficient (PYY-/-) mice. The water-soluble GPR119 agonist, AR440006 (that cannot traverse epithelial tight junctions), elicited responses, when added apically or basolaterally in mouse and human colonic mucosae. In both species, GPR119 responses were PYY, Y1 receptor mediated, and glucose dependent. AR440006 efficacy matched the GI distribution of L-cells in WT tissues but was absent from GPR119-/- tissue. OEA and 2-OG responses were significantly reduced in the GPR119-/- colon, but OLDA responses were unchanged. Alternative L-cell activation via free fatty acid receptors 1, 3, and 4 and the G protein-coupled bile acid receptor TGR5 or by the melanocortin 4 receptor, was unchanged in GPR119-/- tissues. The GPR119 agonist slowed transit in WT but not the PYY-/- colon in vitro. AR440006 (intraperitoneally) slowed WT colonic and upper-GI transit significantly in vivo. These data indicate that luminal or blood-borne GPR119 agonism can stimulate L-cell PYY release with paracrine consequences and slower motility. We suggest that this glucose-dependent L-cell response to a gut-restricted GPR119 stimulus has potential therapeutic advantage in modulating insulinotropic signaling with reduced risk of hypoglycemia.

The current state of GPCR-based drug discovery to treat metabolic disease

One approach of modern drug discovery is to identify agents that enhance or diminish signal transduction cascades in various cell types and tissues by modulating the activity of GPCRs. This strategy has resulted in the development of new medicines to treat many conditions, including cardiovascular disease, psychiatric disorders, HIV/AIDS, certain forms of cancer and Type 2 diabetes mellitus (T2DM). These successes justify further pursuit of GPCRs as disease targets and provide key learning that should help guide identifying future therapeutic agents. This report reviews the current landscape of GPCR drug discovery with emphasis on efforts aimed at developing new molecules for treating T2DM and obesity. We analyse historical efforts to generate GPCR-based drugs to treat metabolic disease in terms of causal factors leading to success and failure in this endeavour.

LINKED ARTICLES

This article is part of a themed section on Molecular Pharmacology of GPCRs. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.21/issuetoc.

YH18968, a Novel 1,2,4-Triazolone G-Protein Coupled Receptor 119 Agonist for the Treatment of Type 2 Diabetes Mellitus

G protein-coupled receptor 119 (GPR119) is expressed in the pancreas and gastrointestinal tract, and its activation promotes insulin secretion in the beta cells of the pancreatic islets as well as the secretion of glucagon-like peptide-1 (GLP-1) in intestinal L cells, consequently improving glucose-stimulated insulin secretion. Due to this dual mechanism of action, the development of small-molecule GPR119 agonists has received significant interest for the treatment of type 2 diabetes. We newly synthesized 1,2,4-triazolone derivatives of GPR119 agonists, which demonstrated excellent outcomes in a cyclic adenosine monophosphate (cAMP) assay. Among the synthesized derivatives, YH18968 showed cAMP=2.8 nM; in GLUTag cell, GLP-1secretion=2.3 fold; in the HIT-T15 cell, and insulin secretion=1.9 fold. Single oral administration of YH18968 improved glucose tolerance and combined treatment with a dipeptidyl peptidase 4 (DPP-4) inhibitor augmented the glucose lowering effect as well as the plasma level of active GLP-1 in normal mice. Single oral administration of YH18968 improved glucose tolerance in a diet induced obese mice model. This effect was maintained after repeated dosing for 4 weeks. The results indicate that YH18968 combined with a DPP-4 inhibitor may be an effective therapeutic candidate for the treatment of type 2 diabetes.

Structure and biological activity of endogenous and synthetic agonists of GPR119

A G-protein-coupled receptor, GPR119, is a promising pharmacological target for a new class of hypoglycaemic drugs with an original mechanism of action, namely, increase in the glucose-dependent incretin and insulin secretion. In 2005, the first ligands were found and in the subsequent years, a large number of GPR119 agonists were synthesized in laboratories in various countries; the safest and most promising agonists have entered phase I and II clinical trials as agents for the treatment of type 2 diabetes mellitus and obesity. The review describes the major endogenous GPR119 agonists and the main trends in the design and modification of synthetic structures for increasing the hypoglycaemic activity. The data on synthetic agonists are arranged according to the type of the central core of the molecules.

The bibliography includes 104 references.

Therapeutic application of GPR119 ligands in metabolic disorders

GPR119 belongs to the G protein-coupled receptor family and exhibits dual modes of action upon ligand-dependent activation: pancreatic secretion of insulin in a glucose-dependent manner and intestinal secretion of incretins. Hence, GPR119 has emerged as a promising target for treating type 2 diabetes mellitus without causing hypoglycaemia. However, despite continuous efforts by many major pharmaceutical companies, no synthetic GPR119 ligand has been approved as a new class of anti-diabetic agents thus far, nor has any passed beyond phase II clinical studies. Herein, we summarize recent advances in research concerning the physiological/pharmacological effects of GPR119 and its synthetic ligands on the regulation of energy metabolism, and we speculate on future applications of GPR119 ligands for the treatment of metabolic diseases, focusing on non-alcoholic fatty liver disease.

Chemistry and Hypoglycemic Activity of GPR119 Agonist ZB-16

This article is to highlight the chemical properties and primary pharmacology of novel GPR119 agonist ZB-16 and its analogs, which were rejected during the screening. Experiments were performed in vitro (specific activity, metabolism and cell toxicity) and in vivo (hypoglycemic activity and pharmacokinetics). ZB-16 exhibits nanomolar activity (EC50 = 7.3-9.7 nM) on target receptor GPR119 in vitro associated with hypoglycemic activity in vivo. In animals with streptozotocin-nicotinamide induced type 2 diabetes mellitus (STZ-NA T2D) daily oral dose of ZB-16 (1 mg/kg) or sitagliptin (10 mg/kg) for 28 days resulted in the reduction of blood glucose levels. The effects of ZB-16 were comparable to the hypoglycemic action of sitagliptin. ZB-16 demonstrated relatively low plasma exposition, high distribution volume, mild clearance and a prolonged half-life (more than 12 h). The present study demonstrates that the targeted search for selective GPR119 receptor agonists is a well-founded approach for developing novel drugs for the therapy of T2D. Based on the combination of high in vitro activity (compared to competitor standards), a useful ADME profile, distinct hypoglycemic activity which is comparable to the efficacy of sitagliptin in rats with experimental T2D, and the acceptable pharmacokinetic profile, we recommend the ZB-16 compound for further research.

Dissecting the Physiology and Pathophysiology of Glucagon-Like Peptide-1

An aging world population exposed to a sedentary life style is currently plagued by chronic metabolic diseases, such as type-2 diabetes, that are spreading worldwide at an unprecedented rate. One of the most promising pharmacological approaches for the management of type 2 diabetes takes advantage of the peptide hormone glucagon-like peptide-1 (GLP-1) under the form of protease resistant mimetics, and DPP-IV inhibitors. Despite the improved quality of life, long-term treatments with these new classes of drugs are riddled with serious and life-threatening side-effects, with no overall cure of the disease. New evidence is shedding more light over the complex physiology of GLP-1 in health and metabolic diseases. Herein, we discuss the most recent advancements in the biology of gut receptors known to induce the secretion of GLP-1, to bridge the multiple gaps into our understanding of its physiology and pathology.

Gut Microbiota Dysbiosis Drives and Implies Novel Therapeutic Strategies for Diabetes Mellitus and Related Metabolic Diseases

Accumulating evidence over the past decade has linked the development of metabolic syndrome related to diabetes to variations in gut microbiota, an emerging, critical homeostatic regulator of host energy metabolism and immune responses. Mechanistic studies in rodent models have revealed an ever-increasing multitude of molecular mechanisms whereby the gut microbiota interacts with various host sensing and signaling pathways, leading to modulation of endocrine system, immune responses, nervous system activity, and hence, the predisposition to metabolic diseases. Remarkably, the microbiota-driven immune responses in metabolic tissues and the host nutrient-sensing mechanisms of gut microbial metabolites, in particular short-chain fatty acids, have been significantly associated with the proneness to diabetes and related disorders. This review will synthesize the recent efforts on unraveling the mediating role of gut microbiota in the pathogenesis of metabolic diseases, aiming to reveal new therapeutic opportunities.

Trends in GPCR drug discovery: new agents, targets and indications

G protein-coupled receptors (GPCRs) are the most intensively studied drug targets, mostly due to their substantial involvement in human pathophysiology and their pharmacological tractability. Here, we report an up-to-date analysis of all GPCR drugs and agents in clinical trials, which reveals current trends across molecule types, drug targets and therapeutic indications, including showing that 475 drugs (~34% of all drugs approved by the US Food and Drug Administration (FDA)) act at 108 unique GPCRs. Approximately 321 agents are currently in clinical trials, of which ~20% target 66 potentially novel GPCR targets without an approved drug, and the number of biological drugs, allosteric modulators and biased agonists has increased. The major disease indications for GPCR modulators show a shift towards diabetes, obesity and Alzheimer disease, although several central nervous system disorders are also highly represented. The 224 (56%) non-olfactory GPCRs that have not yet been explored in clinical trials have broad untapped therapeutic potential, particularly in genetic and immune system disorders. Finally, we provide an interactive online resource to analyse and infer trends in GPCR drug discovery.

Commensal bacteria make GPCR ligands that mimic human signalling molecules

Commensal bacteria are believed to have important roles in human health. The mechanisms by which they affect mammalian physiology remain poorly understood, but bacterial metabolites are likely to be key components of host interactions. Here we use bioinformatics and synthetic biology to mine the human microbiota for N-acyl amides that interact with G-protein-coupled receptors (GPCRs). We found that N-acyl amide synthase genes are enriched in gastrointestinal bacteria and the lipids that they encode interact with GPCRs that regulate gastrointestinal tract physiology. Mouse and cell-based models demonstrate that commensal GPR119 agonists regulate metabolic hormones and glucose homeostasis as efficiently as human ligands, although future studies are needed to define their potential physiological role in humans. Our results suggest that chemical mimicry of eukaryotic signalling molecules may be common among commensal bacteria and that manipulation of microbiota genes encoding metabolites that elicit host cellular responses represents a possible small-molecule therapeutic modality (microbiome-biosynthetic gene therapy).

Design, synthesis, and biological evaluation of aryl N-methoxyamide derivatives as GPR119 agonists

A series of N-methoxyamide derivatives was identified and evaluated as GPR119 agonists. Several N-methoxyamides with thienopyrimidine and pyridine scaffolds showed potent GPR119 agonistic activities. Among them, compound 9c displayed good in vitro activity and potency. Moreover, compound 9c lowered glucose excursion in mice in an oral glucose tolerance test and increased GLP-1 secretion in intestinal cells.

YH18421, a novel GPR119 agonist exerts sustained glucose lowering and weight loss in diabetic mouse model

G-protein-coupled receptor 119 (GPR119) represents a promising target for the treatment of type 2 diabetes as it can increase both GLP-1 secretion from intestinal L cells and glucose-stimulated insulin secretion (GSIS) from pancreatic β cells. Due to this dual mechanism of action, the development of small molecule GPR119 agonists has received much interest for the treatment of type 2 diabetes. Here, we identified a novel small-molecule GPR119 agonist, YH18421 and evaluated its therapeutic potential. YH18421 specifically activated human GPR119 with high potency and potentiated GLP-1 secretion and GSIS in vitro cell based systems. In normal mice, single oral administration of YH18421 improved glucose tolerance. Combined treatment of YH18421 and the DPP-4 inhibitor augmented both plasma active GLP-1 levels and glycemic control. In diet induced obese (DIO) mice model, glucose lowering effect of YH18421 was maintained after 4 weeks of repeat dosing and YH18421 acted additively with DPP-IV inhibitor. We also observed that YH18421 inhibited weight gain during 4 weeks of administration in DIO mice. These data demonstrate that YH18421 is capable of delivering sustained glucose control and preventing weight gain and combination with the DPP-IV inhibitor maybe an effective strategy for the treatment of type 2 diabetes.

β-Cell Inactivation of Gpr119 Unmasks Incretin Dependence of GPR119-Mediated Glucoregulation

GPR119 was originally identified as an orphan β-cell receptor; however, subsequent studies demonstrated that GPR119 also regulates β-cell function indirectly through incretin hormone secretion. We assessed the importance of GPR119 for β-cell function in Gpr119^-/- mice and in newly generated Gpr119^βcell-/- mice. Gpr119^-/- mice displayed normal body weight and glucose tolerance on a regular chow (RC) diet. After high-fat feeding, Gpr119^-/- mice exhibited reduced fat mass, decreased levels of circulating adipokines, improved insulin sensitivity, and better glucose tolerance. Unexpectedly, oral and intraperitoneal glucose tolerance and the insulin response to glycemic challenge were not perturbed in Gpr119^βcell-/- mice on RC and high-fat diets. Moreover, islets from Gpr119^-/- and Gpr119^βcell-/- mice exhibited normal insulin responses to glucose and β-cell secretagogues. Furthermore, the selective GPR119 agonist AR231453 failed to directly enhance insulin secretion from perifused islets. In contrast, AR231453 increased plasma glucagon-like peptide 1 (GLP-1) and insulin levels and improved glucose tolerance in wild-type and Gpr119^βcell-/- mice. These findings demonstrate that β-cell GPR119 expression is dispensable for the physiological control of insulin secretion and the pharmacological response to GPR119 agonism, findings that may inform the lack of robust efficacy in clinical programs assessing GPR119 agonists for the therapy of type 2 diabetes.

Synthesis and biological evaluation of pyrimidine derivatives with diverse azabicyclic ether/amine as novel GPR119 agonist

A class of novel pyrimidine derivatives bearing diverse conformationally restricted azabicyclic ether/amine were designed, synthesized and evaluated for their GPR119 agonist activities against type 2 diabetes. Most compounds exhibited superior hEC₅₀ values to endogenous lipid oleoylethanolamide (OEA). Analogs with 2-fluoro substitution in the aryl ring showed more potent GPR119 activation than those without fluorine. Especially compound 27m synthesized from endo-azabicyclic alcohol was observed to have the best EC₅₀ value (1.2nM) and quite good agonistic activity (112.2% max) as a full agonist.

ZB-16, a Novel GPR119 Agonist, Relieves the Severity of Streptozotocin-Nicotinamide-Induced Diabetes in Rats

GPR119 is involved in the regulation of incretin and insulin secretion, so the GPR119 agonists have been suggested as novel antidiabetic medications. The purpose of this work was to assess the influence of novel GPR119 agonist ZB-16 on the glucose utilization, insulin, and glucagon-like peptide-1 (GLP-1) secretion and the morphology of pancreas in rats with streptozotocin-nicotinamide-induced diabetes. 45 male Wistar rats were used in the study. The criteria of streptozotocin-nicotinamide-induced diabetes were blood glucose levels of 9-14 mmol/l measured in fasting conditions on the third day since administration of streptozotocin (65 mg/kg) and nicotinamide (230 mg/kg). Animals failed to reach the criteria were excluded from the experiment. The substances were administered per os once per day for 28 days. Measurements included blood glucose monitoring (every 7 days), glucose tolerance test (every 14 days), the assessment of insulin and GLP-1 levels in blood plasma (28 days after beginning), and the results of immunohistochemical staining of pancreas. It was found that ZB-16 (1 mg/kg per os, once a day) decreases the blood glucose levels under fasting conditions and improves the glucose utilization. These changes were associated with the increase in stimulated secretion of GLP-1 and insulin, accompanied by the growth of insulin-positive cells in pancreas. Thus, ZB-16 could be a promising antidiabetic drug for oral administration.

Synthesis and biological evaluation of 1, 2, 4-oxadiazole derivatives as novel GPR119 agonists

A series of 1, 2, 4-oxadiazole derivatives have been designed and synthesized, and 25 compounds were evaluated their abilities by the assay of cAMP concentration in GPR119-transfected HEK293T cells. All compounds showed acceptable agonistic effects on GPR119. Among these compounds, 4p exhibited the best agonistic effects with the EC₅₀ of 20.6 nm, which was comparable to that of positive control GPR119 agonist GSK1292263. The agonistic activity of these 1,2,4-oxadiazole derivatives led to the establishment of a structure-activity relationship.

Never Waste a Good Crisis: Confronting Reproducibility in Translational Research

The lack of reproducibility of preclinical experimentation has implications for sustaining trust in and ensuring the viability and funding of the academic research enterprise. Here I identify problematic behaviors and practices and suggest solutions to enhance reproducibility in translational research.

GPR119 Agonist AS1269574 Activates TRPA1 Cation Channels to Stimulate GLP-1 Secretion

GPR119 is a G protein-coupled receptor expressed on intestinal L cells that synthesize and secrete the blood glucose-lowering hormone glucagon-like peptide-1 (GLP-1). GPR119 agonists stimulate the release of GLP-1 from L cells, and for this reason there is interest in their potential use as a new treatment for type 2 diabetes mellitus. AS1269574 is one such GPR119 agonist, and it is the prototype of a series of 2,4,6 trisubstituted pyrimidines that exert positive glucoregulatory actions in mice. Here we report the unexpected finding that AS1269574 stimulates GLP-1 release from the STC-1 intestinal cell line by directly promoting Ca(2+) influx through transient receptor potential ankyrin 1 (TRPA1) cation channels. These GPR119-independent actions of AS1269574 are inhibited by TRPA1 channel blockers (AP-18, A967079, HC030031) and are not secondary to intracellular Ca(2+) release or cAMP production. Patch clamp studies reveal that AS1269574 activates an outwardly rectifying membrane current with properties expected of TRPA1 channels. However, the TRPA1 channel-mediated action of AS1269574 to increase intracellular free calcium concentration is not replicated by GPR119 agonists (AR231453, oleoylethanolamide) unrelated in structure to AS1269574. Using human embryonic kidney-293 cells expressing recombinant rat TRPA1 channels but not GPR119, direct TRPA1 channel activating properties of AS1269574 are validated. Because we find that AS1269574 also acts in a conventional GPR119-mediated manner to stimulate proglucagon gene promoter activity in the GLUTag intestinal L cell line, new findings reported here reveal the surprising capacity of AS1269574 to act as a dual agonist at two molecular targets (GPR119/TRPA1) important to the control of L-cell function and type 2 diabetes mellitus drug discovery research.