ABSTRACT
Sleep disturbances are associated with various metabolic diseases such as hypertension and diabetes. We had previously established a mouse model of a psychophysiological stress-induced chronic sleep disorder (CSD) characterized by disrupted circadian rhythms of wheel-running activity, core body temperature, and sleep-wake cycles. To evaluate the underlying mechanisms of metabolic disorders induced by CSD, we created mice with CSD for six weeks and fed them with a high-fat diet. Glucose intolerance with hyperglycemia resulted, although plasma insulin levels and body weight increases were identical between control and CSD mice. Gluconeogenesis and glycolysis were enhanced and suppressed, respectively, in the livers of CSD mice, because the mRNA expression of Pck1 was significantly increased, whereas that of Gck and Pklr were significantly decreased in the CSD mice. Adipose inflammation induced by the high-fat diet seemed suppressed by the CSD, because the mRNA expression levels of Adgre1, Ccl2, and Tnf were significantly downregulated in the adipose tissues of CSD mice. These findings suggest that CSD impair glucose tolerance by inducing gluconeogenesis and suppressing glycolysis. Hyperphasia with hypoleptinemia, hypercorticosteronemia, and increased plasma free fatty acids might be involved in the impaired glucose metabolism under a CSD. Further studies are needed to elucidate the endocrine and molecular mechanisms underlying the associations between sleep disorders and impaired glucose homeostasis that consequently causes diabetes.
Subject(s)
Glucose Intolerance/etiology , Glucose Intolerance/physiopathology , Sleep Wake Disorders/etiology , Sleep Wake Disorders/physiopathology , Stress, Psychological/complications , Stress, Psychological/physiopathology , Animals , Chronic Disease , Cytokines/metabolism , Male , Mice , Panniculitis/etiology , Panniculitis/physiopathologyABSTRACT
The efficacy and tolerability of once weekly dulaglutide 0.75 mg in Japanese patients with type 2 diabetes (T2D) were evaluated by subgroups defined by key demographic characteristics. This post hoc analysis included data from patients who received dulaglutide 0.75 mg for up to 26 weeks in three phase 3 trials (one open-label, randomized; one double-blind and open-label, randomized; one open-label, nonrandomized). Patients were classified into subgroups on the basis of sex (male, female), age (<65, ≥65 years), body weight (<70, ≥70 kg), body mass index (BMI; <25, ≥25 kg/m(2)), duration of diabetes (<7, ≥7 years), HbA1c (≤8.5, >8.5%), use of concomitant sulfonylurea (yes, no), and use of concomitant biguanide (yes, no). Efficacy measures analyzed were changes from baseline in HbA1c and body weight and percentages of patients achieving HbA1c <7.0%. Safety measures analyzed were incidence of hypoglycemia and nausea and change from baseline in seated pulse rate. A total of 855 patients were analyzed. Once weekly dulaglutide 0.75 mg improved blood glucose control as measured by HbA1c regardless of patient characteristics; patients with higher baseline HbA1c values had greater improvements compared to patients with lower baseline values. Weight loss was greater in patients with lower baseline HbA1c and in patients taking concomitant biguanides. Concomitant use of sulfonylureas had the greatest effect on the incidence of hypoglycemia. Treatment of T2D with once weekly dulaglutide 0.75 mg for 26 weeks was associated with significant improvement in glycemic control irrespective of age, sex, duration of diabetes, body weight, BMI, or concomitant medication.
Subject(s)
Diabetes Mellitus, Type 2/drug therapy , Glucagon-Like Peptide-1 Receptor/agonists , Glucagon-Like Peptides/analogs & derivatives , Hyperglycemia/prevention & control , Hypoglycemia/prevention & control , Hypoglycemic Agents/therapeutic use , Immunoglobulin Fc Fragments/therapeutic use , Recombinant Fusion Proteins/therapeutic use , Aged , Biguanides/administration & dosage , Biguanides/adverse effects , Biguanides/therapeutic use , Body Mass Index , Combined Modality Therapy/adverse effects , Diabetes Mellitus, Type 2/blood , Diabetes Mellitus, Type 2/complications , Diabetes Mellitus, Type 2/therapy , Double-Blind Method , Drug Administration Schedule , Drug Therapy, Combination/adverse effects , Female , Glucagon-Like Peptide-1 Receptor/metabolism , Glucagon-Like Peptides/administration & dosage , Glucagon-Like Peptides/adverse effects , Glucagon-Like Peptides/therapeutic use , Glycated Hemoglobin/analysis , Humans , Hypoglycemia/chemically induced , Hypoglycemia/epidemiology , Hypoglycemic Agents/administration & dosage , Hypoglycemic Agents/adverse effects , Immunoglobulin Fc Fragments/administration & dosage , Immunoglobulin Fc Fragments/adverse effects , Male , Middle Aged , Nausea/chemically induced , Nausea/epidemiology , Overweight/complications , Overweight/diet therapy , Overweight/therapy , Recombinant Fusion Proteins/administration & dosage , Recombinant Fusion Proteins/adverse effects , Sulfonylurea Compounds/administration & dosage , Sulfonylurea Compounds/adverse effects , Sulfonylurea Compounds/therapeutic use , Weight Loss/drug effectsABSTRACT
Psychological stressors prominently affect diurnal rhythms, including locomotor activity, sleep, blood pressure, and body temperature, in humans. Here, we found that a novel continuous stress imposed by the perpetual avoidance of water on a wheel (PAWW) affected several physiological diurnal rhythms in mice. One week of PAWW stress decayed robust circadian locomotor rhythmicity, while locomotor activity was evident even during the light period when the mice are normally asleep. Daytime activity was significantly upregulated, whereas nighttime activity was downregulated, resulting in a low amplitude of activity. Total daily activity gradually decreased with increasing exposure to PAWW stress. The mice could be exposed to PAWW stress for over 3 weeks without adaptation. Furthermore, continuous PAWW stress enhanced food intake, but decreased body weight and plasma leptin levels, indicating that sleep loss and PAWW stress altered the energy balance in these mice. The diurnal rhythm of corticosterone levels was not severely affected. The body temperature rhythm was diurnal in the stressed mice, but significantly dysregulated during the dark period. Plasma catecholamines were elevated in the stressed mice. Continuous PAWW stress reduced the duration of daytime sleep, especially during the first half of the light period, and increased nighttime sleepiness. Continuous PAWW stress also simultaneously obscured sleep/wake and locomotor activity rhythms compared with control mice. These sleep architecture phenotypes under stress are similar to those of patients with insomnia. The stressed mice could be entrained to the light/dark cycle, and when they were transferred to constant darkness, they exhibited a free-running circadian rhythm with a timing of activity onset predicted by the phase of their entrained rhythms. Circadian gene expression in the liver and muscle was unaltered, indicating that the peripheral clocks in these tissues remained intact.
Subject(s)
Circadian Rhythm/physiology , Motor Activity/physiology , Sleep Disorders, Circadian Rhythm/etiology , Stress, Psychological/physiopathology , Water , ARNTL Transcription Factors/metabolism , Analysis of Variance , Animals , Body Temperature Regulation/physiology , Catecholamines/blood , Corticosterone/blood , DNA Primers/genetics , Electroencephalography , Enzyme-Linked Immunosorbent Assay , Gene Expression Regulation/physiology , Male , Mice , Period Circadian Proteins/metabolism , Real-Time Polymerase Chain Reaction , Stress, Psychological/complicationsABSTRACT
Glucokinase activators (GKAs) are small-molecule agents that enhance glucose sensing by pancreatic ß cells and glucose metabolism by hepatocytes. There is strong interest in these agents as potential therapies for type 2 diabetes. Here, we report key pharmacokinetic and pharmacodynamic findings from preclinical studies of the GKA 3-[[6-(ethylsulfonyl)-3-pyridinyl]oxy]-5-[(1S)-2-hydroxy-1-methylethoxy]-N-(1-methyl-1H-pyrazol-3-yl)benzamide (MK-0941). Incubated in vitro with recombinant human glucokinase, 1 µM MK-0941 lowered the S(0.5) of this enzyme for glucose from 6.9 to 1.4 mM and increased the maximum velocity of glucose phosphorylation by 1.5-fold. In 2.5 and 10 mM glucose, the EC(50) values for activation of GK by MK-0941 were 0.240 and 0.065 µM, respectively. Treatment of isolated rat islets of Langerhans and hepatocytes with 10 µM MK-0941 increased insulin secretion by 17-fold and glucose uptake up to 18-fold, respectively. MK-0941 exhibited strong glucose-lowering activity in C57BL/6J mice maintained on a high-fat diet (HFD), db/db mice, HFD plus low-dose streptozotocin-treated mice, and nondiabetic dogs. In both mice and dogs, oral doses of MK-0941 were rapidly absorbed and rapidly cleared from the blood; plasma levels reached maximum within 1 h and fell thereafter with a half-life of ~2 h. During oral glucose tolerance testing in dogs, MK-0941 reduced total area-under-the-curve postchallenge (0-2 h) plasma glucose levels by up to 48% compared with vehicle-treated controls. When administered twice daily to mice for 16 days, and once daily to the dog for 4 days, MK-0941 remained efficacious on successive days. These findings support further investigation of MK-0941 as a potential therapeutic agent for treatment of type 2 diabetes.
Subject(s)
Benzamides/pharmacokinetics , Diabetes Mellitus, Type 2/enzymology , Disease Models, Animal , Glucokinase/metabolism , Hypoglycemic Agents/pharmacokinetics , Sulfones/pharmacokinetics , Animals , Benzamides/pharmacology , Blood Glucose/drug effects , Blood Glucose/metabolism , Cells, Cultured , Diabetes Mellitus, Type 2/drug therapy , Dogs , Enzyme Activation/drug effects , Enzyme Activation/physiology , Humans , Hypoglycemic Agents/pharmacology , Hypoglycemic Agents/therapeutic use , Male , Mice , Mice, Inbred C57BL , Mice, Inbred ICR , Rats , Rats, Sprague-Dawley , Rats, Wistar , Sulfones/pharmacologyABSTRACT
We investigated the long-term effect of a glucokinase (GK) activator (GKA) on the changes in hepatic gene expression, glucose metabolism, lipid profiles and hepatic function in wild-type mice and the haploinsufficiency of ß-cell-specific GK mice on a high-fat (HF) diet. Twenty weeks of GKA treatment had no effect on hepatic GK activity or expression of genes related to glucose or lipid metabolism, suggesting that chronic GK activation by GKA showed a sustained reduction of ambient blood glucose levels without causing significant impact on hepatic lipid and glucose metabolisms. Furthermore, GKA exerted glucose-lowering efficacy lasted for up to 40 weeks without increasing bodyweight or exerting adverse effects on lipid metabolism or hepatic function in either genotype on the HF diet. The present results show that GKA is capable of chronically improving glucose metabolism in mice on the HF diet without exerting a harmful influence on their lipid profile or hepatic function. (J Diabetes Invest,doi: 10.1111/j.2040-1124.2011.00103.x, 2011).
ABSTRACT
Glucokinase activators increase insulin release from pancreatic beta-cells and hepatic glucose utilization by modifying the activity of glucokinase, a key enzyme in glucose-sensing and glycemic regulation. Sulfonylureas are antihyperglycemic agents that stimulate insulin secretion via a glucose-independent mechanism that is vulnerable to secondary failure through beta-cell desensitization. The present study determined whether glucokinase activator treatment retains its glucose-lowering efficacy in male, adult, non-diabetic Sprague-Dawley rats desensitized to sulfonylurea treatment and whether glucose-lowering during chronic glucokinase activator treatment is subject to secondary failure. Animals were given food containing either glimepiride (a sulfonylurea), Compound B (3-[(1S)-2-hydroxy-1-methylethoxy]-5-[4-(methylsulfonyl)phenoxy]-N-1,3-thiazol-2-ylbenzamide, an experimental glucokinase activator), or no drug for up to 5 weeks. Food containing 0.04% of either drug produced acute (within 4-8 h) and significant (P<0.05) reductions in blood glucose to approximately 50% of control levels. Chronic treatment with either 0.01% or 0.04% glimepiride resulted in complete failure of glucose-lowering efficacy within 3 days whereas the efficacy of Compound B was sustained throughout the entire study. Glipizide, also a sulfonylurea, had no glucose-lowering effect when given by gavage (3mg/kg) to glimepiride-desensitized animals whereas Compound B retained full glucose-lowering efficacy in glimepiride-desensitized animals. Oral glucose tolerance was significantly impaired, compared with controls, in animals treated with glimepiride for two weeks but was enhanced to a small extent in animals treated with Compound B. Compound B also significantly increased pancreatic insulin content, compared with controls. These findings suggest that Compound B has sustained glucose-lowering effects in a rat model of sulfonylurea failure.
Subject(s)
Blood Glucose/metabolism , Glucokinase/metabolism , Sulfonylurea Compounds/pharmacology , Animals , Drug Interactions , Enzyme Activation/drug effects , Ethers/chemistry , Ethers/pharmacology , Hydrocarbons, Fluorinated/chemistry , Hydrocarbons, Fluorinated/pharmacology , Insulin/metabolism , Male , Pancreas/drug effects , Pancreas/metabolism , Rats , Rats, Sprague-Dawley , Time FactorsABSTRACT
We describe design, syntheses and structure-activity relationships of a novel class of 4,6-disubstituted quinazoline glucokinase activators. Prototype quinazoline leads (4 and 5) were designed based on the X-ray analyses of the previous 2-aminobenzamide lead classes. Modifications of the quinazoline leads led to the identification of a potent GK activator (21d).
Subject(s)
Glucokinase/chemistry , Hypoglycemic Agents/chemistry , Quinazolines/chemistry , Animals , Blood Glucose/analysis , Drug Discovery , Glucokinase/metabolism , Hypoglycemic Agents/chemical synthesis , Hypoglycemic Agents/pharmacology , Mice , Quinazolines/chemical synthesis , Quinazolines/pharmacology , Rats , Rats, Sprague-Dawley , Structure-Activity RelationshipABSTRACT
The optimization of a series of benzimidazole glucokinase activators is described. We identified a novel and potent achiral benzimidazole derivative as an allosteric GK activator. This activator was designed and synthesized via removal of the chiral center of the lead compound, 6-(N-acylpyrrolidin-2-yl)benzimidazole. The activator exhibited good PK profiles in rats and dogs, and significant hypoglycemic efficacy at 1 mg/kg po dosing in a rat OGTT model. The binding site and binding mode of the benzimidazole class of GKA with GK protein was confirmed by X-ray crystallographic analysis.
Subject(s)
Benzimidazoles/chemical synthesis , Glucokinase/drug effects , Allosteric Regulation/drug effects , Animals , Benzimidazoles/pharmacology , Binding Sites , Crystallography, X-Ray , Dogs , Drug Design , Hypoglycemic Agents/chemical synthesis , RatsABSTRACT
The synthesis and structure-activity-relationships (SARs) of novel 2-(pyridine-2-yl)-1H-benzimidazole glucokinase activators are described. Systematic modification of benzimidazole lead 5a identified from a high-throughput screening led to the discovery of a potent and metabolically stable glucokinase activator 16p(R) with greater structural diversity from GKAs reported to date. The compound also demonstrated acute oral glucose lowering efficacy in rat OGTT model.
Subject(s)
Benzimidazoles/chemical synthesis , Glucokinase/metabolism , Allosteric Site , Animals , Benzimidazoles/pharmacology , Binding Sites , Chemistry, Pharmaceutical/methods , Diabetes Mellitus, Experimental/drug therapy , Drug Design , Enzyme Activation , Glucose Tolerance Test , Hypoglycemic Agents/chemical synthesis , Hypoglycemic Agents/pharmacology , Models, Chemical , Molecular Conformation , Rats , Structure-Activity RelationshipABSTRACT
The optimization of our lead GK activator 2a to 3-[(1S)-2-hydroxy-1-methylethoxy]-5-[4-(methylsulfonyl)phenoxy]-N-1,3-thiazol-2-ylbenzamide (6g), a potent GK activator with good oral availability, is described, including to uncouple the relationship between potency and hydrophobicity. Following oral administration, this compound exhibited robust glucose lowering in diabetic model rodents.
Subject(s)
Benzamides/chemistry , Benzamides/pharmacology , Enzyme Activation/drug effects , Enzyme Activators/chemistry , Enzyme Activators/pharmacology , Glucokinase/chemistry , Glucokinase/metabolism , Animals , Dogs , Humans , Male , Mice , Molecular Structure , Rats , Structure-Activity RelationshipABSTRACT
Glucagon-like peptide-1 (GLP-1) is an incretin hormone that potentiates insulin secretion in a glucose-dependent manner. Selective GLP-1 secretagogue would be one of the potential therapeutic targets for type 2 diabetes. Here, we describe a newly identified small molecule compound (compound A) that stimulates secretion of GLP-1 in murine enteroendocrine cell lines, STC-1 and GLUTag cells, and in primary cultured fetal rat intestinal cells (FRIC). The underlying mechanism by which compound A stimulated GLP-1 secretion was also examined. Compound A stimulated GLP-1 secretion from STC-1 cells in a concentration-dependent manner, and also from GLUTag cells and FRIC. The action of compound A was selective against other tested endocrine functions such as secretion of insulin from rat islets, growth hormone from rat pituitary gland cells, and norepinephrine from rat PC-12 cells. In STC-1 cells, the compound A-stimulated GLP-1 secretion was neither due to cyclic AMP production nor to Ca(2+) release from intracellular stores, but to extracellular Ca(2+) influx. The response was inhibited by the presence of either L-type Ca(2+) channel blockers or K(+) ionophore. Perforated-patch clamp study revealed that compound A induces membrane depolarization. These results suggest that neither Galphas- nor Galphaq-coupled signaling account for the mechanism of action, but depolarization-coupled Ca(2+) influx from extracellular space is the primary cause for the GLP-1 secretion stimulated by compound A. Identifying a specific target molecule for compound A will reveal a selective regulatory pathway that leads to depolarization-mediated GLP-1 secretion.
Subject(s)
Calcium Channel Agonists/pharmacology , Calcium/metabolism , Glucagon-Like Peptide 1/metabolism , Membrane Potentials/drug effects , Secretory Pathway/drug effects , Animals , Calcium/physiology , Calcium Channel Blockers/pharmacology , Cells, Cultured , Drug Evaluation, Preclinical , Enteroendocrine Cells/drug effects , Enteroendocrine Cells/metabolism , Female , Isoindoles/pharmacology , Male , Membrane Potentials/physiology , Mice , Oxazoles/pharmacology , PC12 Cells , Pregnancy , Rats , Rats, Wistar , Substrate Specificity , Verapamil/pharmacologyABSTRACT
A novel class of 3,6-disubstituted 2-pyridinecarboxamide derivatives was designed based on X-ray analysis of the 2-aminobenzamide lead class. Subsequent chemical modification led to the discovery of potent GK activators which eliminate potential toxicity concerns associated with an aniline group of the lead structure. Compound 7 demonstrated glucose lowering effect in a rat OGTT model.
Subject(s)
Amides/chemistry , Glucokinase/metabolism , Hypoglycemic Agents/chemistry , Pyridines/chemistry , Amides/chemical synthesis , Amides/pharmacokinetics , Animals , Crystallography, X-Ray , Disease Models, Animal , Drug Discovery , Glucokinase/chemistry , Hypoglycemic Agents/chemical synthesis , Hypoglycemic Agents/pharmacokinetics , Pyridines/chemical synthesis , Pyridines/pharmacokinetics , Rats , Structure-Activity RelationshipABSTRACT
Identification and synthesis of novel 3-alkoxy-5-phenoxy-N-thiazolyl benzamides as glucokinase activators are described. Removal of an aniline structure of the prototype lead (2a) and incorporation of an alkoxy or phenoxy substituent led to the identification of 3-Isopropoxy-5-[4-(methylsulfonyl)phenoxy]-N-(4-methyl-1,3-thiazol-2-yl)benzamide (27e) as a novel, potent, and orally bioavailable GK activator. Rat oral glucose tolerance test indicated that 27e exhibited a glucose-lowering effect after 10 mg/kg oral administration.
Subject(s)
Benzamides/chemical synthesis , Glucokinase/chemistry , Hypoglycemic Agents/chemical synthesis , Hypoglycemic Agents/pharmacology , Administration, Oral , Allosteric Regulation , Animals , Benzamides/chemistry , Benzamides/pharmacology , Drug Discovery , Glucokinase/metabolism , Glucose/metabolism , Hypoglycemic Agents/chemistry , Male , Mice , Mice, Inbred ICR , Rats , Rats, Wistar , Structure-Activity RelationshipABSTRACT
The identification and structure-activity-relationships (SARs) of novel 2-amino benzamide glucokinase activators are described. Compounds in this series were developed to be potent GK activators, and their binding mode to the GK protein was determined by crystal structure analysis. In vivo pharmacokinetic and acute in vivo efficacy studies of compound 18 are also described.
Subject(s)
Benzamides/chemistry , Glucokinase/metabolism , Allosteric Regulation/drug effects , Allosteric Regulation/physiology , Animals , Benzamides/pharmacology , Binding Sites/drug effects , Binding Sites/physiology , Enzyme Activation/drug effects , Enzyme Activation/physiology , Male , Rats , Rats, Wistar , Structure-Activity RelationshipABSTRACT
We investigated the effect of glucokinase activator (GKA) on glucose metabolism and beta-cell mass. We analyzed four mouse groups: wild-type mice and beta-cell-specific haploinsufficiency of glucokinase gene (Gck(+/-)) mice on a high-fat (HF) diet. Each genotype was also treated with GKA mixed in the HF diet. Rodent insulinoma cells and isolated islets were used to evaluate beta-cell proliferation by GKA. After 20 wk on the above diets, there were no differences in body weight, lipid profiles, and liver triglyceride content among the four groups. Glucose tolerance was improved shortly after the GKA treatment in both genotypes of mice. beta-Cell mass increased in wild-type mice compared with Gck(+/-) mice, but a further increase was not observed after the administration of GKA in both genotypes. Interestingly, GKA was able to up-regulate insulin receptor substrate-2 (Irs-2) expression in insulinoma cells and isolated islets. The administration of GKA increased 5-bromo-2-deoxyuridine (BrdU) incorporation in insulinoma cells, and 3 d administration of GKA markedly increased BrdU incorporation in mice treated with GKA in both genotypes, compared with those without GKA. In conclusion, GKA was able to chronically improve glucose metabolism for mice on the HF diet. Although chronic GKA administration failed to cause a further increase in beta-cell mass in vivo, GKA was able to increase beta cell proliferation in vitro and with a 3-d administration in vivo. This apparent discrepancy can be explained by a chronic reduction in ambient blood glucose levels by GKA treatment.
Subject(s)
Glucokinase/metabolism , Glucose/metabolism , Hypoglycemic Agents/pharmacology , Insulin-Secreting Cells/cytology , Animals , Body Weight/drug effects , Bromodeoxyuridine/pharmacokinetics , Cells, Cultured , Diet, Atherogenic , Dietary Fats/pharmacology , Drug Evaluation, Preclinical , Enzyme Activation/drug effects , Enzyme Activation/physiology , Glucokinase/genetics , Glucose Intolerance/drug therapy , Hypoglycemic Agents/therapeutic use , Insulin/metabolism , Insulin Receptor Substrate Proteins/genetics , Insulin Receptor Substrate Proteins/metabolism , Insulin Secretion , Insulin-Secreting Cells/drug effects , Insulin-Secreting Cells/metabolism , Mice , Mice, Transgenic , Organ Size/drug effectsABSTRACT
To investigate the effect of elevation of liver glycogen synthase (GYS2) activity on glucose and glycogen metabolism, we performed adenoviral overexpression of the mutant GYS2 with six serine-to-alanine substitutions in rat primary hepatocytes. Cell-free assays demonstrated that the serine-to-alanine substitutions caused constitutive activity and electrophoretic mobility shift. In rat primary hepatocytes, overexpression of the mutant GYS2 significantly reduced glucose production by 40% and dramatically induced glycogen synthesis via the indirect pathway rather than the direct pathway. Thus, we conclude that elevation of glycogen synthase activity has an inhibitory effect on glucose production in hepatocytes by shunting gluconeogenic precursors into glycogen. In addition, although intracellular compartmentation of glucose-6-phosphate (G6P) remains unclear in hepatocytes, our results imply that there are at least two G6P pools via gluconeogenesis and due to glucose phosphorylation, and that G6P via gluconeogenesis is preferentially used for glycogen synthesis in hepatocytes.
Subject(s)
Alanine/genetics , Glycogen Synthase/biosynthesis , Hepatocytes/metabolism , Serine/genetics , Amino Acid Substitution , Animals , Cells, Cultured , Glucose/biosynthesis , Glucose-6-Phosphate/metabolism , Glycogen/metabolism , Glycogen Synthase/genetics , Male , Rats , Rats, WistarABSTRACT
Glucokinase (GK) plays a key role in the control of blood glucose homeostasis. We identified a small molecule GK activator, compound A, that increased the glucose affinity and maximal velocity (V(max)) of GK. Compound A augmented insulin secretion from isolated rat islets and enhanced glucose utilization in primary cultured rat hepatocytes. In rat oral glucose tolerance tests, orally administrated compound A lowered plasma glucose elevation with a concomitant increase in plasma insulin and hepatic glycogen. In liver, GK activity is acutely controlled by its association to the glucokinase regulatory protein (GKRP). In order to decipher the molecular aspects of how GK activator affects the shuttling of GK between nucleus and cytoplasm, the effect of compound A on GK-GKRP interaction was further investigated. Compound A increased the level of cytoplasmic GK in both isolated rat primary hepatocytes and the liver tissues from rats. Experiments in a cell-free system revealed that compound A interacted with glucose-bound free GK, thereby impairing the association of GK and GKRP. On the other hand, compound A did not bind to glucose-unbound GK or GKRP-associated GK. Furthermore, we found that glucose-dependent GK-GKRP interaction also required ATP. Given the combined prominent role of GK on insulin secretion and hepatic glucose metabolism where the GK-GKRP mechanism is involved, activation of GK has a new therapeutic potential in the treatment of type 2 diabetes.