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Effect of GRP119 Receptor Agonist, Compound MBX-2982, on Activity of Human Glucokinase. Bull Exp Biol Med 2017; 163:695-698. [DOI: 10.1007/s10517-017-3881-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Indexed: 10/18/2022]
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Hameed A, Al-Rashida M, Alharthy RD, Uroos M, Mughal EU, Ali SA, Khan KM. Small molecules as activators in medicinal chemistry (2000-2016). Expert Opin Ther Pat 2017; 27:1089-1110. [PMID: 28673105 DOI: 10.1080/13543776.2017.1349103] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
INTRODUCTION From therapeutic point of view, it is often beneficial to enhance the expression of certain enzymes whose low expression is responsible for the observed ailment. Small molecules as activators of several enzymes have great biological potential as anti-microbial and anti-cancer agents, for the treatment of diabetes, obesity, metabolic disorders, and for the treatment of neurological disorders including Alzheimer's disease. This review covers patents describing small molecules as activators, and provides structural leads for the design of even more potent activators. Area covered: This review is focused on small molecules that have been explored as activators of enzymes in the last and current decade (2000-2016). Expert opinion: The ability to modulate activity of enzymes has long been a quest of medicinal chemistry. This has been the impetus behind the development of a plethora of drugs as enzyme inhibitors. However only a few enzyme activators as drugs have made it to the market. Disorders characterized by supressed enzyme activity can be treated by enhancing the activity of a specific enzyme.
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Affiliation(s)
- Abdul Hameed
- a H. E. J. Research Institute of Chemistry, International Center for Chemical and Biological Sciences , University of Karachi , Karachi , Pakistan
| | - Mariya Al-Rashida
- b Department of Chemistry , Forman Christian College (A Chartered University) , Lahore , Pakistan
| | - Rima D Alharthy
- c Department of Chemistry, Science and Arts College , King Abdulaziz University , Jeddah , Saudi Arabia
| | - Maliha Uroos
- d Institute of Chemistry , University of the Punjab , Lahore , Pakistan
| | | | - Syed Abid Ali
- a H. E. J. Research Institute of Chemistry, International Center for Chemical and Biological Sciences , University of Karachi , Karachi , Pakistan
| | - Khalid Mohammed Khan
- a H. E. J. Research Institute of Chemistry, International Center for Chemical and Biological Sciences , University of Karachi , Karachi , Pakistan
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Discovery of potent and orally active 1,4-disubstituted indazoles as novel allosteric glucokinase activators. Bioorg Med Chem Lett 2017; 27:2678-2682. [DOI: 10.1016/j.bmcl.2017.04.041] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Revised: 04/10/2017] [Accepted: 04/12/2017] [Indexed: 01/23/2023]
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Wang P, Liu H, Chen L, Duan Y, Chen Q, Xi S. Effects of a Novel Glucokinase Activator, HMS5552, on Glucose Metabolism in a Rat Model of Type 2 Diabetes Mellitus. J Diabetes Res 2017; 2017:5812607. [PMID: 28191470 PMCID: PMC5278194 DOI: 10.1155/2017/5812607] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Revised: 12/01/2016] [Accepted: 12/27/2016] [Indexed: 01/20/2023] Open
Abstract
Glucokinase (GK) plays a critical role in the control of whole-body glucose homeostasis. We investigated the possible effects of a novel glucokinase activator (GKA), HMS5552, to the GK in rats with type 2 diabetes mellitus (T2DM). Male Sprague-Dawley (SD) rats were divided into four groups: control group, diabetic group, low-dose (10 mg/kg) HMS5552-treated diabetic group (HMS-L), and high-dose (30 mg/kg) HMS5552-treated diabetic group (HMS-H). HMS5552 was administered intragastrically to the T2DM rats for one month. The levels of total cholesterol, triglyceride, fasting plasma insulin (FINS), and glucagon (FG) were determined, and an oral glucose tolerance test was performed. The expression patterns of proteins and genes associated with insulin resistance and GK activity were assayed. Compared with diabetic rats, the FINS level was significantly decreased in the HMS5552-treated diabetic rats. HMS5552 treatment significantly lowered the blood glucose levels and improved GK activity and insulin resistance. The immunohistochemistry, western blot, and semiquantitative RT-PCR results further demonstrated the effects of HMS5552 on the liver and pancreas. Our data suggest that the novel GKA, HMS5552, exerts antidiabetic effects on the liver and pancreas by improving GK activity and insulin resistance, which holds promise as a novel drug for the treatment of T2DM patients.
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Affiliation(s)
- Ping Wang
- The Key Laboratory of Pharmacology and Medical Molecular Biology, Medical College, Henan University of Science and Technology, Luoyang 471023, China
| | - Huili Liu
- School Clinic, Henan University of Science and Technology, Luoyang 471023, China
| | - Li Chen
- Department of Clinical Research & Development, Hua Medicine, Shanghai 201203, China
| | - Yingli Duan
- The Key Laboratory of Pharmacology and Medical Molecular Biology, Medical College, Henan University of Science and Technology, Luoyang 471023, China
| | - Qunli Chen
- The Key Laboratory of Pharmacology and Medical Molecular Biology, Medical College, Henan University of Science and Technology, Luoyang 471023, China
| | - Shoumin Xi
- The Key Laboratory of Pharmacology and Medical Molecular Biology, Medical College, Henan University of Science and Technology, Luoyang 471023, China
- *Shoumin Xi:
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McCarty MF. In type 1 diabetics, high-dose biotin may compensate for low hepatic insulin exposure, promoting a more normal expression of glycolytic and gluconeogenic enyzymes and thereby aiding glycemic control. Med Hypotheses 2016; 95:45-48. [PMID: 27692165 DOI: 10.1016/j.mehy.2016.08.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Accepted: 08/09/2016] [Indexed: 10/21/2022]
Abstract
In type 1 diabetics, hepatic exposure to insulin is chronically subnormal even in the context of insulin therapy; as a result, expression of glycolytic enzymes is decreased, and that of gluconeogenic enzymes is enhanced, resulting in a physiologically inappropriate elevation of hepatic glucose output. Subnormal expression of glucokinase (GK) is of particular importance in this regard. Possible strategies for correcting this perturbation of hepatic enzyme expression include administration of small molecule allosteric activators of GK, as well as a procedure known as chronic intermittent intravenous insulin therapy (CIIIT); however, side effects accompany the use of GK activators, and CIIIT is time and labor intensive. Alternatively, administration of high-dose biotin has potential for modulating hepatic enzyme expression in a favorable way. Studies in rodents and in cultured hepatocytes demonstrate that, in the context of low insulin exposure, supra-physiological levels of biotin induce increased expression of GK while suppressing that of the key gluconeogenic enzyme phosphoenolpyruvate carboxykinase. These effects may be a downstream consequence of the fact that biotin down-regulates mRNA expression of FOXO1; insulin's antagonism of the activity of this transcription factor is largely responsible for its modulatory impact on hepatic glycolysis and gluconeogenesis. Hence, high-dose biotin may compensate for subnormal insulin exposure by suppressing FOXO1 levels. High-dose biotin also has the potential to oppose hepatic steatosis by down-regulating SREBP-1 expression. Two pilot trials of high-dose biotin (16 or 2mg per day) in type 1 diabetics have yielded promising results. There is also some reason to suspect that high-dose biotin could aid control of diabetic neuropathy and nephropathy via its stimulatory effect on cGMP production. Owing to the safety, good tolerance, moderate expense, and current availability of high-dose biotin, this strategy merits more extensive evaluation in type 1 diabetes.
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Affiliation(s)
- Mark F McCarty
- Catalytic Longevity, 7831 Rush Rose Drive, Apt. 316, Carlsbad, CA 92009, United States.
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Mulley JF, Hargreaves AD, Hegarty MJ, Heller RS, Swain MT. Transcriptomic analysis of the lesser spotted catshark (Scyliorhinus canicula) pancreas, liver and brain reveals molecular level conservation of vertebrate pancreas function. BMC Genomics 2014; 15:1074. [PMID: 25480530 PMCID: PMC4362833 DOI: 10.1186/1471-2164-15-1074] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Accepted: 11/27/2014] [Indexed: 12/20/2022] Open
Abstract
Background Understanding the evolution of the vertebrate pancreas is key to understanding its functions. The chondrichthyes (cartilaginous fish such as sharks and rays) have often been suggested to possess the most ancient example of a distinct pancreas with both hormonal (endocrine) and digestive (exocrine) roles. The lack of genetic, genomic and transcriptomic data for cartilaginous fish has hindered a more thorough understanding of the molecular-level functions of the chondrichthyan pancreas, particularly with respect to their “unusual” energy metabolism (where ketone bodies and amino acids are the main oxidative fuel source) and their paradoxical ability to both maintain stable blood glucose levels and tolerate extensive periods of hypoglycemia. In order to shed light on some of these processes, we carried out the first large-scale comparative transcriptomic survey of multiple cartilaginous fish tissues: the pancreas, brain and liver of the lesser spotted catshark, Scyliorhinus canicula. Results We generated a mutli-tissue assembly comprising 86,006 contigs, of which 44,794 were assigned to a particular tissue or combination of tissues based on mapping of sequencing reads. We have characterised transcripts encoding genes involved in insulin regulation, glucose sensing, transcriptional regulation, signaling and digestion, as well as many peptide hormone precursors and their receptors for the first time. Comparisons to mammalian pancreas transcriptomes reveals that mechanisms of glucose sensing and insulin regulation used to establish and maintain a stable internal environment are conserved across jawed vertebrates and likely pre-date the vertebrate radiation. Conservation of pancreatic hormones and genes encoding digestive proteins support the single, early evolution of a distinct pancreatic gland with endocrine and exocrine functions in jawed vertebrates. In addition, we demonstrate that chondrichthyes lack pancreatic polypeptide (PP) and that reports of PP in the literature are likely due cross-reaction with PYY and/or NPY in the pancreas. A three hormone islet organ is therefore the ancestral jawed vertebrate condition, later elaborated upon only in the tetrapod lineage. Conclusions The cartilaginous fish are a great untapped resource for the reconstruction of patterns and processes of vertebrate evolution and new approaches such as those described in this paper will greatly facilitate their incorporation into the rank of “model organism”. Electronic supplementary material The online version of this article (doi:10.1186/1471-2164-15-1074) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- John F Mulley
- School of Biological Sciences, Bangor University, Brambell Building, Deiniol Road, Bangor, Gwynedd LL57 2UW, United Kingdom.
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Abstract
The glucokinase (GK) enzyme (EC 2.7.1.1.) is essential for the use of dietary glucose because it is the first enzyme to phosphorylate glucose in excess in different key tissues such as the pancreas and liver. The objective of the present review is not to fully describe the biochemical characteristics and the genetics of this enzyme but to detail its nutritional regulation in different vertebrates from fish to human. Indeed, the present review will describe the existence of the GK enzyme in different animal species that have naturally different levels of carbohydrate in their diets. Thus, some studies have been performed to analyse the nutritional regulation of the GK enzyme in humans and rodents (having high levels of dietary carbohydrates in their diets), in the chicken (moderate level of carbohydrates in its diet) and rainbow trout (no carbohydrate intake in its diet). All these data illustrate the nutritional importance of the GK enzyme irrespective of feeding habits, even in animals known to poorly use dietary carbohydrates (carnivorous species).
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Taha MO, Habash M, Khanfar MA. The use of docking-based comparative intermolecular contacts analysis to identify optimal docking conditions within glucokinase and to discover of new GK activators. J Comput Aided Mol Des 2014; 28:509-47. [PMID: 24610240 DOI: 10.1007/s10822-014-9740-4] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2013] [Accepted: 02/25/2014] [Indexed: 11/30/2022]
Abstract
Glucokinase (GK) is involved in normal glucose homeostasis and therefore it is a valid target for drug design and discovery efforts. GK activators (GKAs) have excellent potential as treatments of hyperglycemia and diabetes. The combined recent interest in GKAs, together with docking limitations and shortages of docking validation methods prompted us to use our new 3D-QSAR analysis, namely, docking-based comparative intermolecular contacts analysis (dbCICA), to validate docking configurations performed on a group of GKAs within GK binding site. dbCICA assesses the consistency of docking by assessing the correlation between ligands' affinities and their contacts with binding site spots. Optimal dbCICA models were validated by receiver operating characteristic curve analysis and comparative molecular field analysis. dbCICA models were also converted into valid pharmacophores that were used as search queries to mine 3D structural databases for new GKAs. The search yielded several potent bioactivators that experimentally increased GK bioactivity up to 7.5-folds at 10 μM.
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Affiliation(s)
- Mutasem O Taha
- Drug Discovery Unit, Department of Pharmaceutical Sciences, Faculty of Pharmacy, The University of Jordan, Amman, Jordan,
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Diabetes Mellitus: New Challenges and Innovative Therapies. NEW STRATEGIES TO ADVANCE PRE/DIABETES CARE: INTEGRATIVE APPROACH BY PPPM 2013; 3. [PMCID: PMC7120768 DOI: 10.1007/978-94-007-5971-8_3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Diabetes is a common chronic disease affecting an estimated 285 million adults worldwide. The rising incidence of diabetes, metabolic syndrome, and subsequent vascular diseases is a major public health problem in industrialized countries. This chapter summarizes current pharmacological approaches to treat diabetes mellitus and focuses on novel therapies for diabetes mellitus that are under development. There is great potential for developing a new generation of therapeutics that offer better control of diabetes, its co-morbidities and its complications. Preclinical results are discussed for new approaches including AMPK activation, the FGF21 target, cell therapy approaches, adiponectin mimetics and novel insulin formulations. Gene-based therapies are among the most promising emerging alternatives to conventional treatments. Therapies based on gene silencing using vector systems to deliver interference RNA to cells (i.e. against VEGF in diabetic retinopathy) are also a promising therapeutic option for the treatment of several diabetic complications. In conclusion, treatment of diabetes faces now a new era that is characterized by a variety of innovative therapeutic approaches that will improve quality of life in the near future.
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Effects of a glucokinase activator on hepatic intermediary metabolism: study with 13C-isotopomer-based metabolomics. Biochem J 2012; 444:537-51. [PMID: 22448977 DOI: 10.1042/bj20120163] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
GKAs (glucokinase activators) are promising agents for the therapy of Type 2 diabetes, but little is known about their effects on hepatic intermediary metabolism. We monitored the fate of (13)C-labelled glucose in both a liver perfusion system and isolated hepatocytes. MS and NMR spectroscopy were deployed to measure isotopic enrichment. The results demonstrate that the stimulation of glycolysis by GKA led to numerous changes in hepatic metabolism: (i) augmented flux through the TCA (tricarboxylic acid) cycle, as evidenced by greater incorporation of (13)C into the cycle (anaplerosis) and increased generation of (13)C isotopomers of citrate, glutamate and aspartate (cataplerosis); (ii) lowering of hepatic [Pi] and elevated [ATP], denoting greater phosphorylation potential and energy state; (iii) stimulation of glycogen synthesis from glucose, but inhibition of glycogen synthesis from 3-carbon precursors; (iv) increased synthesis of N-acetylglutamate and consequently augmented ureagenesis; (v) increased synthesis of glutamine, alanine, serine and glycine; and (vi) increased production and outflow of lactate. The present study provides a deeper insight into the hepatic actions of GKAs and uncovers the potential benefits and risks of GKA for treatment of diabetes. GKA improved hepatic bioenergetics, ureagenesis and glycogenesis, but decreased gluconeogenesis with a potential risk of lactic acidosis and fatty liver.
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Vidal-Alabró A, Gómez-Valadés AG, Méndez-Lucas A, Llorens J, Bartrons R, Bermúdez J, Perales JC. Liver Glucokinase(A456V) Induces Potent Hypoglycemia without Dyslipidemia through a Paradoxical Induction of the Catalytic Subunit of Glucose-6-Phosphatase. Int J Endocrinol 2011; 2011:707928. [PMID: 22194744 PMCID: PMC3238378 DOI: 10.1155/2011/707928] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2011] [Accepted: 09/09/2011] [Indexed: 01/07/2023] Open
Abstract
Recent reports point out the importance of the complex GK-GKRP in controlling glucose and lipid homeostasis. Several GK mutations affect GKRP binding, resulting in permanent activation of the enzyme. We hypothesize that hepatic overexpression of a mutated form of GK, GK(A456V), described in a patient with persistent hyperinsulinemic hypoglycemia of infancy (PHHI) and could provide a model to study the consequences of GK-GKRP deregulation in vivo. GK(A456V) was overexpressed in the liver of streptozotocin diabetic mice. Metabolite profiling in serum and liver extracts, together with changes in key components of glucose and lipid homeostasis, were analyzed and compared to GK wild-type transfected livers. Cell compartmentalization of the mutant but not the wild-type GK was clearly affected in vivo, demonstrating impaired GKRP regulation. GK(A456V) overexpression markedly reduced blood glucose in the absence of dyslipidemia, in contrast to wild-type GK-overexpressing mice. Evidence in glucose utilization did not correlate with increased glycogen nor lactate levels in the liver. PEPCK mRNA was not affected, whereas the mRNA for the catalytic subunit of glucose-6-phosphatase was upregulated ~4 folds in the liver of GK(A456V)-treated animals, suggesting that glucose cycling was stimulated. Our results provide new insights into the complex GK regulatory network and validate liver-specific GK activation as a strategy for diabetes therapy.
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Affiliation(s)
- Anna Vidal-Alabró
- Biophysics Unit, Department of Physiological Sciences II, IDIBELL-University of Barcelona, Campus de Bellvitge, 08907 L'Hospitalet de Llobregat, Spain
| | - Alícia G. Gómez-Valadés
- Biophysics Unit, Department of Physiological Sciences II, IDIBELL-University of Barcelona, Campus de Bellvitge, 08907 L'Hospitalet de Llobregat, Spain
| | - Andrés Méndez-Lucas
- Biophysics Unit, Department of Physiological Sciences II, IDIBELL-University of Barcelona, Campus de Bellvitge, 08907 L'Hospitalet de Llobregat, Spain
| | - Jordi Llorens
- Biophysics Unit, Department of Physiological Sciences II, IDIBELL-University of Barcelona, Campus de Bellvitge, 08907 L'Hospitalet de Llobregat, Spain
| | - Ramon Bartrons
- Biophysics Unit, Department of Physiological Sciences II, IDIBELL-University of Barcelona, Campus de Bellvitge, 08907 L'Hospitalet de Llobregat, Spain
| | - Jordi Bermúdez
- Biophysics Unit, Department of Physiological Sciences II, IDIBELL-University of Barcelona, Campus de Bellvitge, 08907 L'Hospitalet de Llobregat, Spain
| | - Jose C. Perales
- Biophysics Unit, Department of Physiological Sciences II, IDIBELL-University of Barcelona, Campus de Bellvitge, 08907 L'Hospitalet de Llobregat, Spain
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Guertin KR. Allosteric Activators of Glucokinase (GK) for the Treatment of Type 2 Diabetes. KINASE DRUG DISCOVERY 2011. [DOI: 10.1039/9781849733557-00244] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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Regulation of glucose metabolism via hepatic forkhead transcription factor 1 (FoxO1) by Morinda citrifolia (noni) in high-fat diet-induced obese mice. Br J Nutr 2011; 108:218-228. [PMID: 22011624 DOI: 10.1017/s0007114511005563] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Renewed interest in alternative medicine among diabetic individuals prompted us to investigate anti-diabetic effects of Morinda citrifolia (noni) in high-fat diet (HFD)-fed mice. Type 2 diabetes is associated with increased glucose production due to the inability of insulin to suppress hepatic gluconeogenesis and promote glycolysis. Insulin inhibits gluconeogenesis by modulating transcription factors such as forkhead box O (FoxO1). Based on microarray analysis data, we tested the hypothesis that fermented noni fruit juice (fNJ) improves glucose metabolism via FoxO1 phosphorylation. C57BL/6 male mice were fed a HFD and fNJ for 12 weeks. Body weights and food intake were monitored daily. FoxO1 expression was analysed by real-time PCR and Western blotting. Specificity of fNJ-associated FoxO1 regulation of gluconeogenesis was confirmed by small interfering RNA (siRNA) studies using human hepatoma cells, HepG2. Supplementation with fNJ inhibited weight gain and improved glucose and insulin tolerance and fasting glucose in HFD-fed mice. Hypoglycaemic properties of fNJ were associated with the inhibition of hepatic FoxO1 mRNA expression, with a concomitant increase in FoxO1 phosphorylation and nuclear expulsion of the proteins. Gluconeogenic genes, phosphoenolpyruvate C kinase (PEPCK) and glucose-6-phosphatase (G6P), were significantly inhibited in mice fed a HFD+fNJ. HepG2 cells demonstrated more than 80 % inhibition of PEPCK and G6P mRNA expression in cells treated with FoxO1 siRNA and fNJ. These data suggest that fNJ improves glucose metabolism via FoxO1 regulation in HFD-fed mice.
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Abstract
The pathophysiology of hyperglycemia in type 2 diabetes (T2DM) involves 3 main defects: insulin deficiency, excess hepatic glucose output, and insulin resistance. Oral anti-diabetic agents act in a variety of ways. These include agents that stimulate insulin secretion, reduce hepatic glucose production, delay digestion and absorption of intestinal carbohydrate or improve insulin action. Because of improved knowledge of pathophysiology, new drugs with mechanisms of action focussed on specific pathophysiological alterations have appeared, in order to utilize all the possibilities of treating this condition. Here, we focus on the new agents used in the latest years and the overcoming ones in future, in particular incretin-based therapies, drugs inhibiting kidney glucose reabsorption (SGLT2 inhibitors), and glucokinase activators. The strategy for new drug development advocated here is to establish a broad range of anti-diabetic medicines with different mechanisms of action and potential opportunities for effective combination therapies.
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Affiliation(s)
- Paolo Cavallo Perin
- Department of Internal Medicine, University of Torino, Corso AM Dogliotti 14, Turin, Italy.
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Gill D, Brocklehurst KJ, Brown HWG, Smith DM. Upregulation of β-cell genes and improved function in rodent islets following chronic glucokinase activation. J Mol Endocrinol 2011; 47:59-67. [PMID: 21571864 DOI: 10.1530/jme-10-0157] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Glucokinase (GK) plays a critical role in controlling blood glucose; GK activators have been shown to stimulate insulin secretion acutely both in vitro and in vivo. Sustained stimulation of insulin secretion could potentially lead to β-cell exhaustion; this study examines the effect of chronic GK activation on β-cells. Gene expression and insulin secretion were measured in rodent islets treated in vitro with GKA71 for 72 h. Key β-cell gene expression was measured in rat, mouse and global GK heterozygous knockout mouse islets (gk(del/wt)). Insulin secretion, after chronic exposure to GKA71, was measured in perifused rat islets. GKA71 acutely increased insulin secretion in rat islets in a glucose-dependent manner. Chronic culture of mouse islets with GKA71 in 5 mmol/l glucose significantly increased the expression of insulin, IAPP, GLUT2, PDX1 and PC1 and decreased the expression of C/EBPβ compared with 5 mmol/l glucose alone. Similar increases were shown for insulin, GLUT2, IAPP and PC1 in chronically treated rat islets. Insulin mRNA was also increased in GKA71-treated gk(del/wt) islets. No changes in GK mRNA were observed. Glucose-stimulated insulin secretion was improved in perifused rat islets following chronic treatment with GKA71. This was associated with a greater insulin content and GK protein level. Chronic treatment of rodent islets with GKA71 showed an upregulation of key β-cell genes including insulin and an increase in insulin content and GK protein compared with glucose alone.
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Affiliation(s)
- D Gill
- AstraZeneca Diabetes and Obesity Drug Discovery, CVGI iMED, 3S42C Mereside, Alderley Park, Macclesfield, Cheshire SK10 4TG, UK
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Rationalization of physicochemical characters and docking of 3-alkoxy-5-phenoxy-N-thiazolyl benzamide analogs toward glucokinase activator activity. Med Chem Res 2011. [DOI: 10.1007/s00044-011-9740-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Abstract
There is a rising worldwide prevalence of diabetes, especially type 2 diabetes mellitus (T2DM), which is one of the most challenging health problems in the 21st century. The associated complications of diabetes, such as cardiovascular disease, peripheral vascular disease, stroke, diabetic neuropathy, amputations, renal failure, and blindness result in increasing disability, reduced life expectancy, and enormous health costs. T2DM is a polygenic disease characterized by multiple defects in insulin action in tissues and defects in pancreatic insulin secretion, which eventually leads to loss of pancreatic insulin-secreting cells. The treatment goals for T2DM patients are effective control of blood glucose, blood pressure, and lipids (if elevated) and, ultimately, to avert the serious complications associated with sustained tissue exposure to excessively high glucose concentrations. Prevention and control of diabetes with diet, weight control, and physical activity has been difficult. Treatment of T2DM has centered on increasing insulin levels, either by direct insulin administration or oral agents that promote insulin secretion, improving sensitivity to insulin in tissues, or reducing the rate of carbohydrate absorption from the gastrointestinal tract. This review presents comprehensive and up-to-date information on the mechanism(s) of action, efficacy, pharmacokinetics, pleiotropic effects, drug interactions, and adverse effects of the newer antidiabetic drugs, including (1) peroxisome proliferator-activated-receptor-γ agonists (thiazolidinediones, pioglitazone, and rosiglitazone); (2) the incretin, glucagon-like peptide-) receptor agonists (incretin-mimetics, exenatide. and liraglutide), (3) inhibitors of dipeptidyl-peptidase-4 (incretin enhancers, sitagliptin, and vildagliptin), (4) short-acting, nonsulfonylurea secretagogue, meglitinides (repaglinide and nateglinide), (5) amylin anlog-pramlintide, (6) α-glucosidase inhibitors (miglitol and voglibose), and (7) colesevelam (a bile acid sequestrant). In addition, information is presented on drug candidates in clinical trials, experimental compounds, and some plants used in the traditional treatment of diabetes based on experimental evidence. In the opinion of this reviewer, therapy based on orally active incretins and incretin mimetics with long duration of action that will be efficacious, preserve the β-cell number/function, and block the progression of diabetes will be highly desirable. However, major changes in lifestyle factors such as diet and, especially, exercise will also be needed if the growing burden of diabetes is to be contained.
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Sarabu R, Berthel SJ, Kester RF, Tilley JW. Novel glucokinase activators: a patent review (2008 - 2010). Expert Opin Ther Pat 2010; 21:13-33. [PMID: 21155690 DOI: 10.1517/13543776.2011.542413] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
IMPORTANCE OF THE FIELD Small molecule glucokinase activators (GKAs) continue to represent a potential strategy to treat type 2 diabetes (T2D). Glucokinase (GK) primarily exerts its effect through modulatory actions in pancreatic β-cells and hepatocytes. It couples insulin secretion in the pancreas with plasma glucose concentration and improves glucose utilization in the liver, thus, affecting two key aspects of glucose homeostasis. There has been an intense interest in GKAs within the pharmaceutical industry ever since the first report of a low molecular mass activator in 2003. The key drivers for this interest are the robust glucose lowering activity observed with GKAs in preclinical T2D animal models and early reports of efficacy in T2D patients. AREAS COVERED IN THIS REVIEW The objective is to review GKA structures disclosed during the 2008 - 2010 period and classify them based on key structural features. For this purpose, only compound data from patent disclosures were used. WHAT THE READER WILL GAIN The reader would gain a detailed view of structural diversity of the GKA field disclosed during the review period. TAKE HOME MESSAGE There continues to be a high level of interest within the pharmaceutical industry in novel GKAs. Several new and highly potent structure types were reported for the first time in the past 3 years. Common features of all of them include a hydrogen bond donor-acceptor pair that makes contact with the backbone CO- and NH- bonds of Arg 63 residue on GK and two hydrophobic groups. During this review period, several GKAs progressed to Phase II clinical testing and the data on their safety and efficacy profiles are eagerly awaited.
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Affiliation(s)
- Ramakanth Sarabu
- Roche Research Center, Roche, 340 Kingsland Street, Nutley, NJ 07110, USA.
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Rideau N, Derouet M, Grimsby J, Simon J. Glucokinase activation induces potent hypoglycemia without recruiting insulin and inhibits food intake in chicken. Gen Comp Endocrinol 2010; 169:276-83. [PMID: 20850445 DOI: 10.1016/j.ygcen.2010.09.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2010] [Revised: 08/27/2010] [Accepted: 09/09/2010] [Indexed: 02/03/2023]
Abstract
Glucose homeostasis exhibits several peculiarities in chickens (in short, presence of high glycemia and resistance to high doses of exogenous insulin). Though the full chicken glucokinase gene sequence is still lacking, several results suggest its existence. The functionality of chicken glucokinase (GK) has been further investigated using an activator of mammalian GK (GKA). In vitro, GKA decreased GK's S0.5(a) in a glucose-dependent manner in liver homogenates from either fasted or fed chickens; it also increased GK Vmax(a) in homogenates from fed chickens. In vivo, acute oral GKA administration (10-100 mg/kg) induced a potent and dose dependent hypoglycemic effect in fed chickens (starting between 15 and 45 min with a maximum effect at 40 mg/kg, P<0.0001). At this dose, plasma insulin levels showed erratic and minor changes in the early times (an increase at 5 min and a decrease at 10 min, P<0.05). At 90 min, when hypoglycemia had developed plasma insulin levels decreased under controls and plasma pancreatic glucagon levels increased over controls. Also at 40 mg/kg, GKA transiently inhibited food intake at about 3h (P<0.0001). In conclusion, GKA is a potent activator of chicken GK evidencing that the structure and the activity of chicken GK are similar to those of mammalian GK. At variance with results obtained in mammals, the potent GKA hypoglycemic action appears to rely mostly on an effect on liver GK in chicken. This fits with previous results and further support the hypothesis of a "deficient coupling" between Β-cell metabolism and insulin release in this species.
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Affiliation(s)
- Nicole Rideau
- INRA, UR83 Recherches Avicoles, 37380 Nouzilly, France.
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Langer S, Kaminski MT, Lenzen S, Baltrusch S. Endogenous activation of glucokinase by 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase is glucose dependent. Mol Endocrinol 2010; 24:1988-97. [PMID: 20702580 DOI: 10.1210/me.2010-0115] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Glucokinase (GK) plays a crucial role as glucose sensor in glucose-induced insulin secretion in pancreatic β-cells. The bifunctional enzyme 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFK-2/FBPase-2) acts as an endogenous GK activator. Therefore, the goal of this study was the analysis of GK-PFK-2/FBPase-2 complex formation and its effect on metabolic stimulus-secretion coupling in β-cells in dependence upon glucose. The interaction between GK and PFK-2/FBPase-2 was analyzed in insulin-secreting MIN6 cells with a new fluorescence-based mammalian two-hybrid system. In contrast to the commonly used mammalian two-hybrid systems that require sampling before detection, the system used allows monitoring of the effects of environmental changes on protein-protein interactions on the single-cell level. Increasing the glucose concentration in the cell culture medium from 3 to 10 and 25 mmol/liter amplified the interaction between the enzymes stepwise. Importantly, in line with these results, overexpression of PFK-2/FBPase-2 in MIN6 cells evoked only at 10 and 25 mmol/liter, an increase in insulin secretion. Furthermore, a PFK-2/FBPase-2 mutant with an abolished GK-binding motif neither showed a glucose-dependent GK binding nor was able to increase insulin secretion. The results obtained with the mammalian two-hybrid system could be confirmed by fluorescence resonance energy transfer experiments in COS cells. Furthermore, the established interaction between GK and the liver GRP served in all experiments as a control. Thus, this study clearly showed that binding and activation of GK by PFK-2/FBPase-2 in β-cells is promoted by glucose, resulting in an enhancement of insulin secretion at stimulatory glucose concentrations, without affecting basal insulin secretion.
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Affiliation(s)
- Sara Langer
- Institute of Clinical Biochemistry, Hannover Medical School, Hannover, Germany
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Ralph EC, Sun S. Biochemical characterization of MODY2 glucokinase variants V62M and G72R reveals reduced enzymatic activities relative to wild type. Biochemistry 2010; 48:2514-21. [PMID: 19187021 DOI: 10.1021/bi900020n] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The glucokinase V62M and G72R mutations are naturally occurring and known to associate with hyperglycemia in humans. Structurally, V62 and G72 residues are located in close proximity to the allosteric site where hypoglycemia-linked activating mutations are clustered. To address the mechanism by which these variants alter the physiological phenotype, we characterized the biochemical and biophysical properties of the enzymes. Recombinant proteins were purified without affinity tags, and their steady-state kinetics and glucose binding affinities were determined. Both enzymes showed reduced rates of turnover (k(cat)) and reduced glucose affinity (i.e., increased K(0.5) and K(D) values). Their thermal stability did not largely differ from that of wild-type glucokinase. However, V62M and G72R lost the stabilizing protein interactions with glucokinase regulatory protein, which may contribute to lower activity in vivo. Both mutants were subject to activation by small molecule activators. In conclusion, the decreased enzyme activities of V62M and G72R observed in this study are consistent with the hyperglycemic phenotype.
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Affiliation(s)
- Erik C Ralph
- Department of Biochemical Pharmacology, La Jolla Laboratories, Pfizer Global Research and Development, San Diego, California 92121, USA
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Sena CM, Bento CF, Pereira P, Seiça R. Diabetes mellitus: new challenges and innovative therapies. EPMA J 2010; 1:138-63. [PMID: 23199048 PMCID: PMC3405309 DOI: 10.1007/s13167-010-0010-9] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2009] [Accepted: 02/04/2010] [Indexed: 12/25/2022]
Abstract
Diabetes mellitus is a widespread disease prevalence and incidence of which increases worldwide. The introduction of insulin therapy represented a major breakthrough in type 1 diabetes; however, frequent hyper- and hypoglycemia seriously affects the quality of life of these patients. New therapeutic approaches, such as whole pancreas transplant or pancreatic islet transplant, stem cell, gene therapy and islets encapsulation are discussed in this review. Regarding type 2 diabetes, therapy has been based on drugs that stimulate insulin secretion (sulphonylureas and rapid-acting secretagogues), reduce hepatic glucose production (biguanides), delay digestion and absorption of intestinal carbohydrate (alpha-glucosidase inhibitors) or improve insulin action (thiazolidinediones). This review is also focused on the newer therapeutically approaches such as incretin-based therapies, bariatric surgery, stem cells and other emerging therapies that promise to further extend the options available. Gene-based therapies are among the most promising emerging alternatives to conventional treatments. Some of these therapies rely on genetic modification of non-differentiated cells to express pancreatic endocrine developmental factors, promoting differentiation of non-endocrine cells into β-cells, enabling synthesis and secretion of insulin in a glucose-regulated manner. Alternative therapies based on gene silencing using vector systems to deliver interference RNA to cells (i.e. against VEGF in diabetic retinopathy) are also a promising therapeutic option for the treatment of several diabetic complications. In conclusion, treatment of diabetes faces now a new era that is characterized by a variety of innovative therapeutic approaches that will improve quality-life and allow personalized therapy-planning in the near future.
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Affiliation(s)
- Cristina M. Sena
- Institute of Physiology, Faculty of Medicine, University of Coimbra, Subunit 1, polo 3, Azinhaga de Santa Comba, Celas, 3000-354 Coimbra, Portugal
- IBILI, University of Coimbra, Coimbra, Portugal
| | - Carla F. Bento
- IBILI, University of Coimbra, Coimbra, Portugal
- Centre of Ophthalmology, Faculty of Medicine, University of Coimbra, Coimbra, Portugal
| | - Paulo Pereira
- IBILI, University of Coimbra, Coimbra, Portugal
- Centre of Ophthalmology, Faculty of Medicine, University of Coimbra, Coimbra, Portugal
| | - Raquel Seiça
- Institute of Physiology, Faculty of Medicine, University of Coimbra, Subunit 1, polo 3, Azinhaga de Santa Comba, Celas, 3000-354 Coimbra, Portugal
- IBILI, University of Coimbra, Coimbra, Portugal
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Wei P, Shi M, Barnum S, Cho H, Carlson T, Fraser JD. Effects of glucokinase activators GKA50 and LY2121260 on proliferation and apoptosis in pancreatic INS-1 beta cells. Diabetologia 2009; 52:2142-50. [PMID: 19641898 DOI: 10.1007/s00125-009-1446-0] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/27/2009] [Accepted: 06/11/2009] [Indexed: 01/24/2023]
Abstract
AIMS/HYPOTHESIS Glucokinase (GK), an enzyme that phosphorylates glucose to form glucose 6-phosphate, serves as the glucose sensor that regulates insulin secretion in beta cells. GK activators (GKAs) activate GK via binding to an allosteric site of the enzyme. GKAs increase glucose-stimulated insulin secretion and decrease blood glucose levels. Using the differentiated beta cell line INS-1, we investigated the role of GKAs in promoting beta cell growth and survival and preventing beta cell apoptosis induced by chronic exposure to high levels of glucose. METHODS Proliferation was assessed using BrdU incorporation. Apoptosis was measured using caspase-3 activity. Immunoblot analysis was used to detect protein levels and the degree of phosphorylation. RESULTS The GK agonists GKA50 and LY2121260 increased both cell replication and cell numbers when tested at basal levels of glucose (3 mmol/l) in INS-1 cells. GKAs promoted INS-1 cell proliferation via upregulation of insulin receptor substrate-2 and subsequent activation of protein kinase B phosphorylation. GKA50 also prevented the INS-1 cell apoptosis that was induced by chronic high glucose conditions, probably via an increase in GK protein levels and normalisation of the apoptotic protein BCL2-associated agonist of cell death (BAD) and its phosphorylation. As a result of the reduction in cell apoptosis, GKA50 prevented cell loss and maintained glucose-stimulated insulin secretion. In addition, the anti-apoptotic activity of GKA50 was significantly abrogated by other GKAs that do not inhibit apoptosis, suggesting that direct binding of GKA50 to GK is essential for its anti-apoptotic effect. CONCLUSION/INTERPRETATION Our results suggest novel roles of GKAs in promoting beta cell growth and preventing chronic-hyperglycaemia-induced beta cell apoptosis. Thus, GKAs may provide novel therapeutics that increase beta cell mass to maintain euglycaemia in diabetes.
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Affiliation(s)
- P Wei
- Diabetes Biology Department, Pfizer Global Research and Development, La Jolla Laboratories, CA 92121, USA.
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Affiliation(s)
- Stephanie A. Amiel
- From the Department of Medicine, King's College London School of Medicine, London, England
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Pal M. Recent advances in glucokinase activators for the treatment of type 2 diabetes. Drug Discov Today 2009; 14:784-92. [DOI: 10.1016/j.drudis.2009.05.013] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2009] [Revised: 05/02/2009] [Accepted: 05/20/2009] [Indexed: 10/20/2022]
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Gorman T, Hope DCD, Brownlie R, Yu A, Gill D, Löfvenmark J, Wedin M, Mayers RM, Snaith MR, Smith DM. Effect of high-fat diet on glucose homeostasis and gene expression in glucokinase knockout mice. Diabetes Obes Metab 2008; 10:885-97. [PMID: 18034843 DOI: 10.1111/j.1463-1326.2007.00819.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
AIM We have generated a heterozygous glucokinase knockout mouse (gk(del/wt)), upon which we investigated the effect of high-fat diet (HFD) with respect to metabolic control and both hepatic and beta-cell gene expression. We also investigated the in vitro efficacy of a glucokinase activator (GKA) on glucose-stimulated insulin secretion (GSIS) in gk(del/wt)mouse islets. METHODS Male gk(del/wt)and gk(wt/wt)mice were grouped (n = 8-10) at 10 weeks of age and fed HFD or chow diet (CD) for 10 weeks. Multiple parameters including blood glucose, plasma insulin and glucose tolerance were assessed. Further animal groups were used for in vitro GSIS and islet and liver gene expression analysis. RESULTS AND CONCLUSIONS gk(del/wt)mice showed early-onset persistent hyperglycaemia, raised glycated haemoglobin levels, impaired GSIS and glucose tolerance but no change in plasma cholesterol, non-esterified fatty acids or triglyceride levels. After HFD feeding, insulin levels of gk(del/wt)mice were less than half that of gk(wt/wt)mice, although they were equivalent to gk(wt/wt)mice on CD. While gk(wt/wt)mice maintained moderate hyperglycaemia, gk(del/wt)mice became overtly diabetic, with worsened glucose tolerance. A GKA (GKA50) increased GSIS, at 10 mM glucose, in gk(del/wt)mice to an extent at least as great as that seen in gk(wt/wt)mice on both CD and HFD. gk(del/wt)mice showed only a small number of changes in gene expression compared with gk(wt/wt)mice. We propose the high fat-fed gk(del/wt)mouse as a model of type 2 diabetes and report retained efficacy of a GKA on in vitro GSIS.
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Affiliation(s)
- T Gorman
- Diabetes & Obesity Drug Discovery, AstraZeneca, Macclesfield, Cheshire, UK.
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Henry RR. Evolving concepts of type 2 diabetes management with oral medications: new approaches to an old disease. Curr Med Res Opin 2008; 24:2189-202. [PMID: 18573228 DOI: 10.1185/03007990802212981] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
BACKGROUND Type 2 diabetes is often accompanied by co-morbid conditions such as hypertension and dyslipidemia, which, coupled with persistent hyperglycemia, result in significant macrovascular and microvascular complications. Type 2 diabetes treatments focus primarily on controlling hyperglycemia, hypertension, and dyslipidemia to stabilize the disease and minimize complications. Despite treatment, control of hyperglycemia and the conditions associated with type 2 diabetes are suboptimal in the majority of patients. Research efforts have concentrated on the development of new therapies for type 2 diabetes, including agents that could be used both as monotherapy and in combination with established oral antidiabetic agents to improve glycemic control and reduce the disease burden on patients. OBJECTIVE To review published literature on oral agents in development for type 2 diabetes, with a focus on their mechanism of action and impact on concomitant risk factors. METHODS After identifying oral agents in late-stage development for type 2 diabetes using the R&D Insight database, a literature review was conducted through PubMed for studies (preferably randomized, controlled trials) on dipeptidyl peptidase-IV inhibitors, CB(1) cannabinoid receptor blockers, and bile acid sequestrants. Where limited published data were available, abstracts from recent major conferences were searched. Other emerging therapies targeting pathways involved in modifying insulin resistance, glycogenolysis, and gluconeogenesis are also discussed. CONCLUSIONS A variety of novel therapies for type 2 diabetes are in development, which will provide patients and diabetes care providers more choices for the management of this disease. Importantly, many of these treatments offer the potential to significantly improve multiple metabolic parameters.
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Johnson D, Shepherd RM, Gill D, Gorman T, Smith DM, Dunne MJ. Glucose-dependent modulation of insulin secretion and intracellular calcium ions by GKA50, a glucokinase activator. Diabetes 2007; 56:1694-702. [PMID: 17360975 DOI: 10.2337/db07-0026] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Because glucokinase is a metabolic sensor involved in the regulated release of insulin, we have investigated the acute actions of novel glucokinase activator compound 50 (GKA50) on islet function. Insulin secretion was determined by enzyme-linked immunosorbent assay, and microfluorimetry with fura-2 was used to examine intracellular Ca(2+) homeostasis ([Ca(2+)](i)) in isolated mouse, rat, and human islets of Langerhans and in the MIN6 insulin-secreting mouse cell line. In rodent islets and MIN6 cells, 1 micromol/l GKA50 was found to stimulate insulin secretion and raise [Ca(2+)](i) in the presence of glucose (2-10 mmol/l). Similar effects on insulin release were also seen in isolated human islets. GKA50 (1 micromol/l) caused a leftward shift in the glucose-concentration response profiles, and the half-maximal effective concentration (EC(50)) values for glucose were shifted by 3 mmol/l in rat islets and approximately 10 mmol/l in MIN6 cells. There was no significant effect of GKA50 on the maximal rates of glucose-stimulated insulin secretion. In the absence of glucose, GKA50 failed to elevate [Ca(2+)](i) (1 micromol/l GKA50) or to stimulate insulin release (30 nmol/l-10 micromol/l GKA50). At 5 mmol/l glucose, the EC(50) for GKA50 in MIN6 cells was approximately 0.3 micromol/l. Inhibition of glucokinase with mannoheptulose or 5-thioglucose selectively inhibited the action of GKA50 on insulin release but not the effects of tolbutamide. Similarly, 3-methoxyglucose prevented GKA50-induced rises in [Ca(2+)](i) but not the actions of tolbutamide. Finally, the ATP-sensitive K(+) channel agonist diazoxide (200 micromol/l) inhibited GKA50-induced insulin release and its elevation of [Ca(2+)](i.) We show that GKA50 is a glucose-like activator of beta-cell metabolism in rodent and human islets and a Ca(2+)-dependent modulator of insulin secretion.
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Affiliation(s)
- Daniel Johnson
- Faculty of Life Sciences, Core Technology Facility, University of Manchester, Manchester, UK
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Fyfe MCT, White JR, Taylor A, Chatfield R, Wargent E, Printz RL, Sulpice T, McCormack JG, Procter MJ, Reynet C, Widdowson PS, Wong-Kai-In P. Glucokinase activator PSN-GK1 displays enhanced antihyperglycaemic and insulinotropic actions. Diabetologia 2007; 50:1277-87. [PMID: 17415548 DOI: 10.1007/s00125-007-0646-8] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/16/2007] [Accepted: 02/02/2007] [Indexed: 10/23/2022]
Abstract
AIMS/HYPOTHESIS We evaluated the insulinotropic and antihyperglycaemic actions of glucokinase activators (GKAs), especially through acute and subchronic studies in rodent diabetes models with (2R)-2-(4-cyclopropanesulphonylphenyl)-N-(5-fluorothiazol-2-yl)-3-(tetrahydropyran-4-yl)propionamide (PSN-GK1), a novel and potent GKA. MATERIALS AND METHODS The action of PSN-GK1 on or in the following were investigated: (1) on human liver glucokinase, insulin secretion from MIN6 cells and 2-deoxy-D: -[(3)H]glucose (2-DG) uptake into rat hepatocytes; and (2) in Zucker diabetic fatty rats and in non-diabetic C57Bl/6, diabetic db/db and ob/ob mice. RESULTS At 5 mmol/l glucose, PSN-GK1 activated glucokinase (4.3-fold, median effective concentration [EC(50)] 130 nmol/l), increased MIN6 insulin secretion (26-fold, EC(50) 267 nmol/l) and 2-DG hepatocytic uptake (threefold, EC(50) 1 micromol/l); at higher glucose concentrations, EC(50)s and fold-effectiveness were both lower. In C57Bl/6 mice, PSN-GK1 reduced blood glucose at 1 and 10 mg/kg (by mouth), but insulin was increased significantly at only the higher dose. In hyperinsulinaemic 10-mmol/l glucose clamps, PSN-GK1 increased 2-DG incorporation into liver glycogen sixfold, directly demonstrating liver effects. PSN-GK1 improved glycaemic profiles in db/db mice and Zucker diabetic fatty rats, diabetic animal models in which GKA efficacy has not previously been described, without causing hypoglycaemia. In ob/ob mice, it dose-dependently reduced excursions in OGTTs. Moreover, after subchronic administration, no tachyphylaxis was evident and glycaemia was improved without alterations to lipid levels, liver weight, glycogen content or body weight. CONCLUSIONS/INTERPRETATION PSN-GK1 was potently antihyperglycaemic through its effects on insulin release and hepatic glucose metabolism. It is one of the most potent GKAs described in the literature and is active in diabetic animal models where GKAs have not been reported to show efficacy to date. Ongoing human trials are investigating the potential of this novel therapeutic approach.
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Affiliation(s)
- M C T Fyfe
- (OSI)Prosidion, Windrush Court, Watlington Road, Oxford, UK.
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Sanz-Rodríguez CE, Concepción JL, Pekerar S, Oldfield E, Urbina JA. Bisphosphonates as inhibitors of Trypanosoma cruzi hexokinase: kinetic and metabolic studies. J Biol Chem 2007; 282:12377-87. [PMID: 17329254 DOI: 10.1074/jbc.m607286200] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Trypanosoma cruzi, the etiologic agent of Chagas disease, has an unusual ATP-dependent hexokinase (TcHK) that is not affected by D-glucose 6-phosphate, but is non-competitively inhibited by inorganic pyrophosphate (PP(i)), suggesting a heterotropic modulator effect. In a previous study we identified a novel family of bisphosphonates, metabolically stable analogs of PP(i), which are potent and selective inhibitors of TcHK as well as the proliferation of the clinically relevant intracellular amastigote form of the parasite in vitro (Hudock, M. P., Sanz-Rodriguez, C. E., Song, Y., Chan, J. M., Zhang, Y., Odeh, S., Kosztowski, T., Leon-Rossell, A., Concepcion, J. L., Yardley, V., Croft, S. L., Urbina, J. A., and Oldfield, E. (2006) J. Med. Chem. 49, 215-223). In this work, we report a detailed kinetic analysis of the effects of three of these bisphosphonates on homogeneous TcHK, as well as on the enzyme in purified intact glycosomes, peroxisome-like organelles that contain most of the glycolytic pathway enzymes in this organism. We also investigated the effects of the same compounds on glucose consumption by intact and digitonin-permeabilized T. cruzi epimastigotes, and on the growth of such cells in liver-infusion tryptose medium. The bisphosphonates investigated were several orders of magnitude more active than PP(i) as non-competitive or mixed inhibitors of TcHK and blocked the use of glucose by the epimastigotes, inducing a metabolic shift toward the use of amino acids as carbon and energy sources. Furthermore, there was a significant correlation between the IC(50) values for TcHK inhibition and those for epimastigote growth inhibition for the 12 most potent compounds of this series. Finally, these bisphosphonates did not affect the sterol composition of the treated cells, indicating that they do not act as inhibitors of farnesyl diphosphate synthase. Taken together, our results suggest that these novel bisphosphonates act primarily as specific inhibitors of TcHK and may represent a novel class of selective anti-T. cruzi agents.
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Affiliation(s)
- Carlos E Sanz-Rodríguez
- Laboratorio de Quimica Biológica, Centro de Biofisica y Bioquímica, Instituto Venezolano de Investigaciones Científicas, Caracas 1020, Venezuela
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Baltrusch S, Langer S, Massa L, Tiedge M, Lenzen S. Improved metabolic stimulus for glucose-induced insulin secretion through GK and PFK-2/FBPase-2 coexpression in insulin-producing RINm5F cells. Endocrinology 2006; 147:5768-76. [PMID: 16980436 DOI: 10.1210/en.2006-0694] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The glucose sensor enzyme glucokinase plays a pivotal role in the regulation of glucose-induced insulin secretion in pancreatic beta-cells. Activation of glucokinase represents a promising concept for the treatment of type 2 diabetes. Therefore, we analyzed the glucokinase activation through its physiological interaction partner, the bifunctional enzyme 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFK-2/FBPase-2) and the resulting effect on glucose metabolism in insulin-producing cells. In RINm5F-GK-PFK-2/FBPase-2 cells stably overexpressing glucokinase plus islet PFK-2/FBPase-2, colocalization between both enzymes as well as elevation of glucokinase activity were significantly increased at a stimulatory glucose concentration of 10 mmol/liter. RINm5F-GK-PFK-2/FBPase-2 cells showed under this culture condition a significant increase in glucose utilization and in the ATP/ADP ratio compared with RINm5F-GK cells, which only overexpress glucokinase. Also glucose-induced insulin secretion was elevated in RINm5F-GK-PFK-2/FBPase-2 cells in comparison to RINm5F-GK cells. Furthermore, pyruvate accumulation and lactate production in RINm5F-GK-PFK-2/FBPase-2 cells were significantly lower at both 10 and 30 mmol/liter glucose than in RINm5F-GK and RINm5F cells. The significant improvement of glucose metabolism after PFK-2/FBPase-2 overexpression is apparently not exclusively the result of high glucokinase enzyme activity. Stabilization of the closed glucokinase conformation by PFK-2/FBPase-2 may not only activate the enzyme but also improve metabolic channeling in beta-cells.
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Affiliation(s)
- Simone Baltrusch
- Institute of Clinical Biochemistry, Hannover Medical School, 30623 Hannover, Germany.
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Coope GJ, Atkinson AM, Allott C, McKerrecher D, Johnstone C, Pike KG, Holme PC, Vertigan H, Gill D, Coghlan MP, Leighton B. Predictive blood glucose lowering efficacy by Glucokinase activators in high fat fed female Zucker rats. Br J Pharmacol 2006; 149:328-35. [PMID: 16921397 PMCID: PMC2014270 DOI: 10.1038/sj.bjp.0706848] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND AND PURPOSE Glucokinase (GK) is the rate-limiting enzyme of hepatic glucose metabolism and acts as a sensor for glucose-stimulated insulin release in beta-cells. Here we examine whether the lowering of blood glucose levels in the rat by small molecule glucokinase activators (GKAs) can be predicted from in vitro enzyme potencies and plasma compound exposure. EXPERIMENTAL APPROACH We developed an insulin resistant and hyperinsulinemic animal model, the high fat fed female Zucker (fa/fa) rat (HFFZ), and measured the acute in vivo glucose-lowering efficacy of a number of GKAs in an oral glucose tolerance test. KEY RESULTS Four GKAs (at 1 to 30 mg kg(-1)), with different in vitro enzyme potencies, dose-dependently improved oral glucose tolerance in HFFZ rats (10-40% decrease glucose area under the curve (AUC) from vehicle control). The extent of glucose lowering, or the pharmacodynamic (PD) effect, of a GKA was directly related to the total compound concentration in the plasma; the pharmacokinetic (PK) measurement. This PK-PD relationship was extended across a series of GKAs by accounting for differences in protein binding and in the in vitro potency. CONCLUSIONS AND IMPLICATIONS When the unbound GKA compound level is greater than the in vitro enzyme potency there was significant blood glucose lowering in vivo. This latter relationship was upheld in non-diabetic Wistar rats orally dosed with a GKA. The robust and predictive nature of the PK-PD relationship for GKAs may prove of value in testing these agents in early human clinical studies.
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Affiliation(s)
- G J Coope
- Cardiovascular and Gastrointestinal Department AstraZeneca, Macclesfield, Cheshire, UK
| | - A M Atkinson
- Cardiovascular and Gastrointestinal Department AstraZeneca, Macclesfield, Cheshire, UK
| | - C Allott
- Cardiovascular and Gastrointestinal Department AstraZeneca, Macclesfield, Cheshire, UK
| | - D McKerrecher
- Cardiovascular and Gastrointestinal Department AstraZeneca, Macclesfield, Cheshire, UK
| | - C Johnstone
- Cardiovascular and Gastrointestinal Department AstraZeneca, Macclesfield, Cheshire, UK
| | - K G Pike
- Cardiovascular and Gastrointestinal Department AstraZeneca, Macclesfield, Cheshire, UK
| | - P C Holme
- Syngenta Central Toxicology Department Macclesfield, Cheshire, UK
| | - H Vertigan
- Cardiovascular and Gastrointestinal Department AstraZeneca, Macclesfield, Cheshire, UK
| | - D Gill
- Cardiovascular and Gastrointestinal Department AstraZeneca, Macclesfield, Cheshire, UK
| | - M P Coghlan
- Cardiovascular and Gastrointestinal Department AstraZeneca, Macclesfield, Cheshire, UK
| | - B Leighton
- Cardiovascular and Gastrointestinal Department AstraZeneca, Macclesfield, Cheshire, UK
- Author for correspondence:
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Heredia VV, Thomson J, Nettleton D, Sun S. Glucose-Induced Conformational Changes in Glucokinase Mediate Allosteric Regulation: Transient Kinetic Analysis. Biochemistry 2006; 45:7553-62. [PMID: 16768451 DOI: 10.1021/bi060253q] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The transient kinetics of glucose binding to glucokinase (GK) was studied using stopped-flow fluorescence spectrophotometry to investigate the underlying mechanism of positive cooperativity of monomeric GK with glucose. Glucose binding to GK was shown to display biphasic kinetics that fit best to a reversible two-step mechanism. GK initially binds glucose to form a transient intermediate, namely, E* x glucose, followed by a conformational change to a catalytically competent E x glucose complex. The microscopic rate constants for each step were determined as follows: on rate k1 of 557 M(-1) s(-1) and off rate k(-1) of 8.1 s(-1) for E* x glucose formation, and forward rate k2 of 0.45 s(-1) and reverse rate k(-2) of 0.28 s(-1) for the conformational change from E* x glucose to E x glucose. These results suggest that the enzyme conformational change induced by glucose binding is a reversible, slow event that occurs outside the catalytic cycle (kcat = 38 s(-1)). This slow transition between the two enzyme conformations modulated by glucose likely forms the kinetic foundation for the allosteric regulation. Furthermore, the kinetics of the enzyme conformational change was altered in favor of E x glucose formation in D2O, accompanied by a decrease in cooperativity with glucose (Hill slope of 1.3 in D2O vs 1.7 in H2O). The deuterium solvent isotope effects confirm the role of the conformational change in the magnitude of glucose cooperativity. Similar studies were conducted with GK activating mutation Y214C at the allosteric activator site that is likely involved in the protein domain rearrangement associated with glucose binding. The mutation enhanced equilibrium glucose binding by a combination of effects on both the formation of E* x glucose and an enzyme conformational change to E x glucose. Kinetic simulation by KINSIM supports the conclusion that the kinetic cooperativity of GK arises from slow glucose-induced conformational changes in GK.
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Affiliation(s)
- Vladi V Heredia
- Biochemical Pharmacology, La Jolla Laboratory, Pfizer Global Research and Development, San Diego, California 92121, USA
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Abstract
Scientists and science in the pharmaceutical industry rely heavily on the more academically orientated basic research carried out at Universities, for first of all training, but also as a source of new ideas and approaches to drug discovery. Progress in the discovery and development of novel therapeutics benefits from a healthy alliance with, and the output from, more basic research institutions, and the reverse is also true, with many advances in understanding of physiological and pathological processes being as the result of the application of novel targeted molecules. To illustrate this, some examples related to the themes of this meeting from my experiences in three different companies will be described. The first involves a metabolic angle in the unravelling of the mechanism of the novel anti-anginal agent ranolazine. The second describes the application of detailed knowledge of insulin structure and action to then use recombinant approaches to design novel molecules to be able to offer the Type I (insulin-dependent) diabetic patient therapies allowing a more physiological treatment regime, and also the further application of learned technology to then discover a means of harnessing the potential of GLP-1 (glucagon-like polypeptide 1) for treating Type II (non-insulin-dependent) diabetes. The last illustrates how findings of novel binding sites on glycogen phosphorylase and glucokinase as the result of drug discovery programmes have led to increased understanding of these key metabolic enzymes and also potential new therapies for Type II diabetes.
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