WorldWideScience

Sample records for glucokinase

  1. Insights into the role of neuronal glucokinase.

    Science.gov (United States)

    De Backer, Ivan; Hussain, Sufyan S; Bloom, Stephen R; Gardiner, James V

    2016-07-01

    Glucokinase is a key component of the neuronal glucose-sensing mechanism and is expressed in brain regions that control a range of homeostatic processes. In this review, we detail recently identified roles for neuronal glucokinase in glucose homeostasis and counterregulatory responses to hypoglycemia and in regulating appetite. We describe clinical implications from these advances in our knowledge, especially for developing novel treatments for diabetes and obesity. Further research required to extend our knowledge and help our efforts to tackle the diabetes and obesity epidemics is suggested. Copyright © 2016 the American Physiological Society.

  2. Insights into the role of neuronal glucokinase

    Science.gov (United States)

    De Backer, Ivan; Hussain, Sufyan S.; Gardiner, James V.

    2016-01-01

    Glucokinase is a key component of the neuronal glucose-sensing mechanism and is expressed in brain regions that control a range of homeostatic processes. In this review, we detail recently identified roles for neuronal glucokinase in glucose homeostasis and counterregulatory responses to hypoglycemia and in regulating appetite. We describe clinical implications from these advances in our knowledge, especially for developing novel treatments for diabetes and obesity. Further research required to extend our knowledge and help our efforts to tackle the diabetes and obesity epidemics is suggested. PMID:27189932

  3. The second activating glucokinase mutation (A456V)

    DEFF Research Database (Denmark)

    Christesen, Henrik B T; Jacobsen, Bendt B; Odili, Stella

    2002-01-01

    for mutations in candidate genes revealed a heterozygous glucokinase mutation in exon 10, substituting valine for alanine at codon 456 (A456V) in the proband and his mother. The purified recombinant glutathionyl S-transferase fusion protein of the A456V glucokinase revealed a decreased glucose S(0.5) (the...

  4. [Glucokinase and glucokinase regulatory proteins as molecular targets for novel antidiabetic drugs].

    Science.gov (United States)

    Rubtsov, P M; Igudin, E L; Tiulpakov, A N

    2015-01-01

    The impairment of glucose homeostasis leads to hyperglycemia and type-2 diabetes mellitus. Glucokinase (GK), an enzyme that catalyzes the conversion of glucose to glucose-6-phosphate in pancreatic ß-cells, liver hepatocytes, specific hypothalamic neurons, and intestine enterocytes, is a key regulator of glucose homeostasis. In hepatocytes, GK controls the glucose uptake and glycogen synthesis and inhibits the glucose synthesis via the gluconeogenesis pathway. Glucokinase regulatory protein (GKRP) synthesized in hepatocytes acts as an endogenous GK inhibitor. During fasting, GKRP binds GK, inactivates it, and transports it into the cell nucleus, thus isolating it from the hepatocyte carbohydrate metabolism. In the beginning of the 2000s, the research was mainly focused on the development and trials of the small molecule GK activators as potential antidiabetic glucose-lowering drugs. However, the use of such substances increased the risk of hypoglycemia, and clinical studies of most synthetic GK activators are currently discontinued. Allosteric inhibitors of the GK-GKRP interaction are coming as alternative agents increasing the GK activity that can substitute GKA. In this review, we discuss the recent advances and the current state of art in the development of potential antidiabetic drugs targeted to GK as a key regulator of glucose homeostasis.

  5. Radioimmunological determination of glucokinase turnover in the rat liver

    International Nuclear Information System (INIS)

    Sibrowski, W.

    1980-01-01

    Synthesis and degradation of glucokinase (GK), key enzyme of glucose utilisation has been investigated in vivo in intact and adrenalectomized rats. Four statements can be made: a pure glucose diet stimulates GK synthesis, glucocorticoids have a permissive effect in the induction of GK sythesis, glucocorticoids do not have any effect in themselves, glucocorticoids affect GK degradation. (orig./AJ) [de

  6. Control of glucokinase translocation in rat hepatocytes by sorbitol and the cytosolic redox state.

    Science.gov (United States)

    Agius, L

    1994-02-15

    In rat hepatocytes cultured in 5 mM glucose, glucokinase activity is present predominantly in a bound state, and during permeabilization of the cells with digitonin in the presence of Mg2+ less than 20% of glucokinase activity is released. However, incubation of hepatocytes with a higher [glucose] [concn. giving half-maximal activation (A50) 15 mM] or with fructose (A50 50 microM) causes translocation of glucokinase from its Mg(2+)-dependent binding site to an alternative site [Agius and Peak (1993) Biochem. J. 296, 785-796]. A comparison of various substrates showed that sorbitol (A50 8 microM) was 6-fold more potent than fructose at causing glucokinase translocation, whereas tagatose was as potent and mannitol was > 10-fold less potent (A50 550 microM). These substrates also stimulate glucose conversion into glycogen with a similar relative potency, suggesting that conversion of glucose into glycogen is dependent on the binding and/or location of glucokinase within the hepatocyte. Ethanol and glycerol inhibited the effects of fructose, sorbitol and glucose on glucokinase translocation, whereas dihydroxy-acetone had a small additive effect at sub-maximal substrate stimulation. The converse effects of glycerol and dihydroxy-acetone suggest a role for the cytosolic NADH/NAD+ redox state in controlling glucokinase translocation. Titrations with three competitive inhibitors of glucokinase did not provide evidence for involvement of glucokinase flux in glucose-induced glucokinase translocation: N-acetylglucosamine inhibited glucose conversion into glycogen, but not glucose-induced glucokinase translocation; glucosamine partially suppressed glucose-induced and fructose-induced glucokinase translocation, at concentrations that caused total inhibition of glucose conversion into glycogen; D-mannoheptulose increased glucokinase release and had an additive effect with glucose. 3,3'-Tetramethylene-glutaric acid (5 mM), an inhibitor of aldose reductase, inhibited glucokinase

  7. Subcellular localization, mobility, and kinetic activity of glucokinase in glucose-responsive insulin-secreting cells.

    Science.gov (United States)

    Stubbs, M; Aiston, S; Agius, L

    2000-12-01

    We investigated the subcellular localization, mobility, and activity of glucokinase in MIN6 cells, a glucose-responsive insulin-secreting beta-cell line. Glucokinase is present in the cytoplasm and a vesicular/granule compartment that is partially colocalized with insulin granules. The granular staining of glucokinase is preserved after permeabilization of the cells with digitonin. There was no evidence for changes in distribution of glucokinase between the cytoplasm and the granule compartment during incubation of the cells with glucose. The rate of release of glucokinase and of phosphoglucoisomerase from digitonin-permeabilized cells was slower when cells were incubated at an elevated glucose concentration (S0.5 approximately 15 mmol/l). This effect of glucose was counteracted by competitive inhibitors of glucokinase (5-thioglucose and mannoheptulose) but was unaffected by fructose analogs and may be due to changes in cell shape or conformation of the cytoskeleton that are secondary to glucose metabolism. Based on the similar release of glucokinase and phosphoglucoisomerase, we found no evidence for specific binding of cytoplasmic digitonin-extractable glucokinase. The affinity of beta-cells for glucose is slightly lower than that in cell extracts and, unlike that in hepatocytes, is unaffected by fructose, tagatose, or a high-K+ medium, which is consistent with the lack of change in glucokinase distribution or release. We conclude that glucokinase is present in two locations, cytoplasm and the granular compartment, and that it does not translocate between them. This conclusion is consistent with the lack of adaptive changes in the glucose phosphorylation affinity. The glucokinase activity associated with the insulin granules may have a role in either direct or indirect coupling between glucose phosphorylation and insulin secretion.

  8. Glucokinase, the pancreatic glucose sensor, is not the gut glucose sensor

    DEFF Research Database (Denmark)

    Murphy, R; Tura, A; Clark, P M

    2008-01-01

    AIMS/HYPOTHESIS: The incretin hormones glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotrophic peptide (GIP) are released from intestinal endocrine cells in response to luminal glucose. Glucokinase is present in these cells and has been proposed as a glucose sensor. The physiological...... role of glucokinase can be tested using individuals with heterozygous glucokinase gene (GCK) mutations. If glucokinase is the gut glucose sensor, GLP-1 and GIP secretion during a 75 g OGTT would be lower in GCK mutation carriers compared with controls. METHODS: We compared GLP-1 and GIP concentrations...... measured at five time-points during a 75 g OGTT in 49 participants having GCK mutations with those of 28 familial controls. Mathematical modelling of glucose, insulin and C-peptide was used to estimate basal insulin secretion rate (BSR), total insulin secretion (TIS), beta cell glucose sensitivity...

  9. Crystallization and preliminary crystallographic analysis of a putative glucokinase/hexokinase from Thermus thermophilus

    International Nuclear Information System (INIS)

    Nakamura, Tsutomu; Kashima, Yasuhiro; Mine, Shouhei; Oku, Takashi; Uegaki, Koichi

    2011-01-01

    In this study, a putative glucokinase/hexokinase from T. thermophilus was purified and crystallized. Diffraction data were collected and processed to 2.02 Å resolution. Glucokinase/hexokinase catalyzes the phosphorylation of glucose to glucose 6-phosphate, which is the first step of glycolysis. The open reading frame TTHA0299 of the extreme thermophile Thermus thermophilus encodes a putative glucokinase/hexokinase which contains the consensus sequence for proteins from the repressors, open reading frames and sugar kinases family. In this study, the glucokinase/hexokinase from T. thermophilus was purified and crystallized using polyethylene glycol 8000 as a precipitant. Diffraction data were collected and processed to 2.02 Å resolution. The crystal belonged to space group P2 1 , with unit-cell parameters a = 70.93, b = 138.14, c = 75.16 Å, β = 95.41°

  10. Specific insulin and proinsulin secretion in glucokinase-deficient individuals

    Directory of Open Access Journals (Sweden)

    V.C. Pardini

    1999-04-01

    Full Text Available Glucokinase (GCK is an enzyme that regulates insulin secretion, keeping glucose levels within a narrow range. Mutations in the glucokinase gene cause a rare form of diabetes called maturity-onset diabetes of the young (MODY. An early onset (less than 25 years, autosomal dominant inheritance and low insulin secretion stimulated by glucose characterize MODY patients. Specific insulin and proinsulin were measured in serum by immunofluorimetric assays (IFMA during a 75-g oral glucose tolerance test (OGTT. Two kindreds (SA and LZ were studied and compared to non-diabetic unrelated individuals (control group 1 matched for age and body mass index (BMI. In one kindred, some of these subjects were also obese (BMI >26 kg/m2, and other family members also presented with obesity and/or late-onset NIDDM. The MODY patients were also compared to a group of five of their first-degree relatives with obesity and/or late-onset NIDDM. The proinsulin profile was different in members of the two MODY kindreds. Fasting proinsulin and the proinsulin/insulin ratio were similar in MODY members of kindred LZ and subjects from control group 1, but were significantly lower than in MODY members of kindred SA (P<0.02 and P<0.01, for proinsulin and proinsulin/insulin ratio, respectively. Moreover, MODY members of family SA had higher levels of proinsulin and proinsulin/insulin ratio, although not significantly different, when compared to their first-degree relatives and to subjects from control group 2. In conclusion, we observed variable degrees of proinsulin levels and proinsulin/insulin ratio in MODY members of two different kindreds. The higher values of these parameters found in MODY and non-MODY members of kindred SA is probably related to the obesity and late-onset NIDDM background present in this family.

  11. Lys169 of human glucokinase is a determinant for glucose phosphorylation: implication for the atomic mechanism of glucokinase catalysis.

    Directory of Open Access Journals (Sweden)

    Jian Zhang

    Full Text Available Glucokinase (GK, a glucose sensor, maintains plasma glucose homeostasis via phosphorylation of glucose and is a potential therapeutic target for treating maturity-onset diabetes of the young (MODY and persistent hyperinsulinemic hypoglycemia of infancy (PHHI. To characterize the catalytic mechanism of glucose phosphorylation by GK, we combined molecular modeling, molecular dynamics (MD simulations, quantum mechanics/molecular mechanics (QM/MM calculations, experimental mutagenesis and enzymatic kinetic analysis on both wild-type and mutated GK. Our three-dimensional (3D model of the GK-Mg(2+-ATP-glucose (GMAG complex, is in agreement with a large number of mutagenesis data, and elucidates atomic information of the catalytic site in GK for glucose phosphorylation. A 10-ns MD simulation of the GMAG complex revealed that Lys169 plays a dominant role in glucose phosphorylation. This prediction was verified by experimental mutagenesis of GK (K169A and enzymatic kinetic analyses of glucose phosphorylation. QM/MM calculations were further used to study the role of Lys169 in the catalytic mechanism of the glucose phosphorylation and we found that Lys169 enhances the binding of GK with both ATP and glucose by serving as a bridge between ATP and glucose. More importantly, Lys169 directly participates in the glucose phosphorylation as a general acid catalyst. Our findings provide mechanistic details of glucose phorphorylation catalyzed by GK, and are important for understanding the pathogenic mechanism of MODY.

  12. Glucokinase gene mutations (MODY 2) in Asian Indians.

    Science.gov (United States)

    Kanthimathi, Sekar; Jahnavi, Suresh; Balamurugan, Kandasamy; Ranjani, Harish; Sonya, Jagadesan; Goswami, Soumik; Chowdhury, Subhankar; Mohan, Viswanathan; Radha, Venkatesan

    2014-03-01

    Heterozygous inactivating mutations in the glucokinase (GCK) gene cause a hyperglycemic condition termed maturity-onset diabetes of the young (MODY) 2 or GCK-MODY. This is characterized by mild, stable, usually asymptomatic, fasting hyperglycemia that rarely requires pharmacological intervention. The aim of the present study was to screen for GCK gene mutations in Asian Indian subjects with mild hyperglycemia. Of the 1,517 children and adolescents of the population-based ORANGE study in Chennai, India, 49 were found to have hyperglycemia. These children along with the six patients referred to our center with mild hyperglycemia were screened for MODY 2 mutations. The GCK gene was bidirectionally sequenced using BigDye(®) Terminator v3.1 (Applied Biosystems, Foster City, CA) chemistry. In silico predictions of the pathogenicity were carried out using the online tools SIFT, Polyphen-2, and I-Mutant 2.0 software programs. Direct sequencing of the GCK gene in the patients referred to our Centre revealed one novel mutation, Thr206Ala (c.616A>G), in exon 6 and one previously described mutation, Met251Thr (c.752T>C), in exon 7. In silico analysis predicted the novel mutation to be pathogenic. The highly conserved nature and critical location of the residue Thr206 along with the clinical course suggests that the Thr206Ala is a MODY 2 mutation. However, we did not find any MODY 2 mutations in the 49 children selected from the population-based study. Hence prevalence of GCK mutations in Chennai is MODY 2 mutations from India and confirms the importance of considering GCK gene mutation screening in patients with mild early-onset hyperglycemia who are negative for β-cell antibodies.

  13. Antidiabetic effects of glucokinase regulatory protein small-molecule disruptors

    Science.gov (United States)

    Lloyd, David J.; St Jean, David J.; Kurzeja, Robert J. M.; Wahl, Robert C.; Michelsen, Klaus; Cupples, Rod; Chen, Michelle; Wu, John; Sivits, Glenn; Helmering, Joan; Komorowski, Renée; Ashton, Kate S.; Pennington, Lewis D.; Fotsch, Christopher; Vazir, Mukta; Chen, Kui; Chmait, Samer; Zhang, Jiandong; Liu, Longbin; Norman, Mark H.; Andrews, Kristin L.; Bartberger, Michael D.; van, Gwyneth; Galbreath, Elizabeth J.; Vonderfecht, Steven L.; Wang, Minghan; Jordan, Steven R.; Véniant, Murielle M.; Hale, Clarence

    2013-12-01

    Glucose homeostasis is a vital and complex process, and its disruption can cause hyperglycaemia and type II diabetes mellitus. Glucokinase (GK), a key enzyme that regulates glucose homeostasis, converts glucose to glucose-6-phosphate in pancreatic β-cells, liver hepatocytes, specific hypothalamic neurons, and gut enterocytes. In hepatocytes, GK regulates glucose uptake and glycogen synthesis, suppresses glucose production, and is subject to the endogenous inhibitor GK regulatory protein (GKRP). During fasting, GKRP binds, inactivates and sequesters GK in the nucleus, which removes GK from the gluconeogenic process and prevents a futile cycle of glucose phosphorylation. Compounds that directly hyperactivate GK (GK activators) lower blood glucose levels and are being evaluated clinically as potential therapeutics for the treatment of type II diabetes mellitus. However, initial reports indicate that an increased risk of hypoglycaemia is associated with some GK activators. To mitigate the risk of hypoglycaemia, we sought to increase GK activity by blocking GKRP. Here we describe the identification of two potent small-molecule GK-GKRP disruptors (AMG-1694 and AMG-3969) that normalized blood glucose levels in several rodent models of diabetes. These compounds potently reversed the inhibitory effect of GKRP on GK activity and promoted GK translocation both in vitro (isolated hepatocytes) and in vivo (liver). A co-crystal structure of full-length human GKRP in complex with AMG-1694 revealed a previously unknown binding pocket in GKRP distinct from that of the phosphofructose-binding site. Furthermore, with AMG-1694 and AMG-3969 (but not GK activators), blood glucose lowering was restricted to diabetic and not normoglycaemic animals. These findings exploit a new cellular mechanism for lowering blood glucose levels with reduced potential for hypoglycaemic risk in patients with type II diabetes mellitus.

  14. Mechanisms of polyphosphate glucokinase and polyphosphate kinase reactions

    International Nuclear Information System (INIS)

    Pepin, C.A.; Robinson, N.A.; Wood, H.G.

    1986-01-01

    Polyphosphate glucokinase [poly(P)GK] catalyzes the following reaction: poly(P)/sub n/ + glucose → poly(P)/sub n-1/ + G-6-P. With long chain poly(P) [n=750 to 400] the mechanism appeared to be processive, in which there is phosphorylation of glucose without release of intermediate sizes of the poly(P) until the chain is about 100, thereafter there were intermediate sizes formed apparently by a non-processive process. Poly(P) kinase catalyzes the following reaction: ATP + poly(P)/sub n/ ↔ ADP + poly(P)/sub n + 1/. Using short chain 32 [P] poly(P) as a primer and non-radioactive ATP, long chain poly(P) is formed processively. The resulting chain has a short length labeled with 32 [P] contributed by the primer on one end and the remainder is made up of unlabeled (P) from the ATP. The authors have used this 32 [P] poly(P) as a substrate with poly(P)GK. If the mechanism of the poly(P)GK were initially processive, there would be a 50% chance the phosphate would be utilized from the unlabeled end and 50% of the 32 [P] would remain in the shortened chain. However, all the 32 [P] was lost when 20% of the poly(P) was converted to G-6-P. In contrast, with poly(P) kinase, the % of poly(P) utilized was equivalent to the % of 32 [P] converted to ATP, which is consistent with a strictly processive mechanism. Even though the mechanism of poly(P)GK appeared to be processive with long chains, the on and off rate of poly(P) from the enzyme is such that there is random removal of (P) from both ends of the poly(P) chain

  15. Discovery of piragliatin--first glucokinase activator studied in type 2 diabetic patients.

    Science.gov (United States)

    Sarabu, Ramakanth; Bizzarro, Fred T; Corbett, Wendy L; Dvorozniak, Mark T; Geng, Wanping; Grippo, Joseph F; Haynes, Nancy-Ellen; Hutchings, Stanley; Garofalo, Lisa; Guertin, Kevin R; Hilliard, Darryl W; Kabat, Marek; Kester, Robert F; Ka, Wang; Liang, Zhenmin; Mahaney, Paige E; Marcus, Linda; Matschinsky, Franz M; Moore, David; Racha, Jagdish; Radinov, Roumen; Ren, Yi; Qi, Lida; Pignatello, Michael; Spence, Cheryl L; Steele, Thomas; Tengi, John; Grimsby, Joseph

    2012-08-23

    Glucokinase (GK) activation as a potential strategy to treat type 2 diabetes (T2D) is well recognized. Compound 1, a glucokinase activator (GKA) lead that we have previously disclosed, caused reversible hepatic lipidosis in repeat-dose toxicology studies. We hypothesized that the hepatic lipidosis was due to the structure-based toxicity and later established that it was due to the formation of a thiourea metabolite, 2. Subsequent SAR studies of 1 led to the identification of a pyrazine-based lead analogue 3, lacking the thiazole moiety. In vivo metabolite identification studies, followed by the independent synthesis and profiling of the cyclopentyl keto- and hydroxyl- metabolites of 3, led to the selection of piragliatin, 4, as the clinical lead. Piragliatin was found to lower pre- and postprandial glucose levels, improve the insulin secretory profile, increase β-cell sensitivity to glucose, and decrease hepatic glucose output in patients with T2D.

  16. Evolution of hepatic glucose metabolism: liver-specific glucokinase deficiency explained by parallel loss of the gene for glucokinase regulatory protein (GCKR.

    Directory of Open Access Journals (Sweden)

    Zhao Yang Wang

    Full Text Available Glucokinase (GCK plays an important role in the regulation of carbohydrate metabolism. In the liver, phosphorylation of glucose to glucose-6-phosphate by GCK is the first step for both glycolysis and glycogen synthesis. However, some vertebrate species are deficient in GCK activity in the liver, despite containing GCK genes that appear to be compatible with function in their genomes. Glucokinase regulatory protein (GCKR is the most important post-transcriptional regulator of GCK in the liver; it participates in the modulation of GCK activity and location depending upon changes in glucose levels. In experimental models, loss of GCKR has been shown to associate with reduced hepatic GCK protein levels and activity.GCKR genes and GCKR-like sequences were identified in the genomes of all vertebrate species with available genome sequences. The coding sequences of GCKR and GCKR-like genes were identified and aligned; base changes likely to disrupt coding potential or splicing were also identified.GCKR genes could not be found in the genomes of 9 vertebrate species, including all birds. In addition, in multiple mammalian genomes, whereas GCKR-like gene sequences could be identified, these genes could not predict a functional protein. Vertebrate species that were previously reported to be deficient in hepatic GCK activity were found to have deleted (birds and lizard or mutated (mammals GCKR genes. Our results suggest that mutation of the GCKR gene leads to hepatic GCK deficiency due to the loss of the stabilizing effect of GCKR.

  17. Nuclear import of glucokinase in pancreatic beta-cells is mediated by a nuclear localization signal and modulated by SUMOylation.

    Science.gov (United States)

    Johansson, Bente Berg; Fjeld, Karianne; Solheim, Marie Holm; Shirakawa, Jun; Zhang, Enming; Keindl, Magdalena; Hu, Jiang; Lindqvist, Andreas; Døskeland, Anne; Mellgren, Gunnar; Flatmark, Torgeir; Njølstad, Pål Rasmus; Kulkarni, Rohit N; Wierup, Nils; Aukrust, Ingvild; Bjørkhaug, Lise

    2017-10-15

    The localization of glucokinase in pancreatic beta-cell nuclei is a controversial issue. Although previous reports suggest such a localization, the mechanism for its import has so far not been identified. Using immunofluorescence, subcellular fractionation and mass spectrometry, we present evidence in support of glucokinase localization in beta-cell nuclei of human and mouse pancreatic sections, as well as in human and mouse isolated islets, and murine MIN6 cells. We have identified a conserved, seven-residue nuclear localization signal ( 30 LKKVMRR 36 ) in the human enzyme. Substituting the residues KK 31,32 and RR 35,36 with AA led to a loss of its nuclear localization in transfected cells. Furthermore, our data indicates that SUMOylation of glucokinase modulates its nuclear import, while high glucose concentrations do not significantly alter the enzyme nuclear/cytosolic ratio. Thus, for the first time, we provide data in support of a nuclear import of glucokinase mediated by a redundant mechanism, involving a nuclear localization signal, and which is modulated by its SUMOylation. These findings add new knowledge to the functional role of glucokinase in the pancreatic beta-cell. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Novel glucokinase mutation in a boy with maturity-onset diabetes of the young

    Directory of Open Access Journals (Sweden)

    Milenković Tatjana

    2008-01-01

    Full Text Available INTRODUCTION Maturity-onset diabetes of the young (MODY is a heterogenous group of disorders characterized by an early onset of insulin-independent diabetes mellitus, an autosomal dominant mode of inheritance and a primary defect in beta-cell. There are six subtypes of MODY. MODY2 and MODY3 are the most frequent. CASE OUTLINE We present a nine-year-old boy with intermittent hyperglycaemia. According to family history, the diagnosis of MODY2 was suspected. Molecular analysis revealed novel missense mutation R250c in exon 7 of glucokinase gene. Mutation (c.748 C>T is the result of substitution of aminoacid cysteine by arginine (p.Arg250Cys. This is the first pediatric patient with MODY2 in Serbia whose diagnosis is established at molecular level. CONCLUSION Molecular diagnosis of MODY has important consequences in terms of prognosis, therapy and family screening of the disorder. Investigation of other patients with MODY2 in our country is important to establish prevalence and nature of mutations in glucokinase gene.

  19. Glucokinase MODY and implications for treatment goals of common forms of diabetes.

    Science.gov (United States)

    Ajjan, Ramzi A; Owen, Katharine R

    2014-12-01

    Treatment goals in diabetes concentrate on reducing the risk of vascular complications, largely through setting targets for glycated haemoglobin (HbA1c). These targets are based on epidemiological studies of complication development, but so far have not adequately addressed the adverse effects associated with lowering HbA1c towards the normal range. Glucokinase (GCK) mutations cause a monogenic form of hyperglycaemia (GCK-MODY) characterised by fasting hyperglycaemia with low postprandial glucose excursions and a marginally elevated HbA1c. Minimal levels of vascular complications (comparable with nondiabetic individuals) are observed in GCK-MODY, leading to the hypothesis that GCK-MODY may represent a useful paradigm for assessing treatment goals in all forms of diabetes. In this review, we discuss the evidence behind this concept, suggest ways of translating this hypothesis into clinical practice and address some of the caveats of such an approach.

  20. Brain glucose sensing, glucokinase and neural control of metabolism and islet function.

    Science.gov (United States)

    Ogunnowo-Bada, E O; Heeley, N; Brochard, L; Evans, M L

    2014-09-01

    It is increasingly apparent that the brain plays a central role in metabolic homeostasis, including the maintenance of blood glucose. This is achieved by various efferent pathways from the brain to periphery, which help control hepatic glucose flux and perhaps insulin-stimulated insulin secretion. Also, critically important for the brain given its dependence on a constant supply of glucose as a fuel--emergency counter-regulatory responses are triggered by the brain if blood glucose starts to fall. To exert these control functions, the brain needs to detect rapidly and accurately changes in blood glucose. In this review, we summarize some of the mechanisms postulated to play a role in this and examine the potential role of the low-affinity hexokinase, glucokinase, in the brain as a key part of some of this sensing. We also discuss how these processes may become altered in diabetes and related metabolic diseases. © 2014 John Wiley & Sons Ltd.

  1. Glucokinase diabetes in 103 families from a country-based study in the Czech Republic: geographically restricted distribution of two prevalent GCK mutations

    DEFF Research Database (Denmark)

    Pruhova, Stepanka; Dusatkova, Petra; Sumnik, Zdenek

    2010-01-01

    Glucokinase diabetes, also called GCK-MODY or maturity-onset diabetes of the young type 2 (MODY2), is caused by heterozygous mutations in the gene encoding glucokinase (GCK). Objective: The aim of study was to investigate the current prevalence of GCK mutations in a large cohort of Czech patients...... with typical clinical appearance of GCK-MODY. In addition, we reanalyzed the negative results obtained previously by screening using the denaturing high-performance liquid chromatography (dHPLC)....

  2. Effects of a glucokinase activator on hepatic intermediary metabolism: study with 13C-isotopomer-based metabolomics

    OpenAIRE

    Nissim, Itzhak; Horyn, Oksana; Nissim, Ilana; Daikhin, Yevgeny; Wehrli, Suzanne L.; Yudkoff, Marc; Matschinsky, Franz M.

    2012-01-01

    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 13C-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 (tricarboxy...

  3. Biotin increases glucokinase expression via soluble guanylate cyclase/protein kinase G, adenosine triphosphate production and autocrine action of insulin in pancreatic rat islets.

    Science.gov (United States)

    Vilches-Flores, Alonso; Tovar, Armando R; Marin-Hernandez, Alvaro; Rojas-Ochoa, Alberto; Fernandez-Mejia, Cristina

    2010-07-01

    Besides its role as a carboxylase prosthetic group, biotin has important effects on gene expression. However, the molecular mechanisms through which biotin exerts these effects are largely unknown. We previously found that biotin increases pancreatic glucokinase expression. We have now explored the mechanisms underlying this effect. Pancreatic islets from Wistar rats were treated with biotin, in the presence or absence of different types of inhibitors. Glucokinase mRNA and 18s rRNA abundance were determined by real-time PCR. Adenosine triphosphate (ATP) content was analyzed by fluorometry. Biotin treatment increased glucokinase mRNA abundance approximately one fold after 2 h; the effect was sustained up to 24 h. Inhibition of soluble guanylate cyclase or protein kinase G (PKG) signalling suppressed biotin-induced glucokinase expression. The cascade of events downstream of PKG in biotin-mediated gene transcription is not known. We found that inhibition of insulin secretion with diazoxide or nifedipine prevented biotin-stimulated glucokinase mRNA increase. Biotin treatment increased islet ATP content (control: 4.68+/-0.28; biotin treated: 6.62+/-0.26 pmol/islet) at 30 min. Inhibition of PKG activity suppressed the effects of biotin on ATP content. Insulin antibodies or inhibitors of phosphoinositol-3-kinase/Akt insulin signalling pathway prevented biotin-induced glucokinase expression. The nucleotide 8-Br-cGMP mimicked the biotin effects. We propose that the induction of pancreatic glucokinase mRNA by biotin involves guanylate cyclase and PKG activation, which leads to an increase in ATP content. This induces insulin secretion via ATP-sensitive potassium channels. Autocrine insulin, in turn, activates phosphoinositol-3-kinase/Akt signalling. Our results offer new insights into the pathways that participate in biotin-mediated gene expression. (c) 2010 Elsevier Inc. All rights reserved.

  4. Dairy Product Consumption Interacts with Glucokinase (GCK Gene Polymorphisms Associated with Insulin Resistance

    Directory of Open Access Journals (Sweden)

    Marine S. Da Silva

    2017-08-01

    Full Text Available Dairy product intake and a person’s genetic background have been reported to be associated with the risk of type 2 diabetes (T2D. The objective of this study was to examine the interaction between dairy products and genes related to T2D on glucose-insulin homeostasis parameters. A validated food frequency questionnaire, fasting blood samples, and glucokinase (GCK genotypes were analyzed in 210 healthy participants. An interaction between rs1799884 in GCK and dairy intake on the homeostasis model assessment of insulin resistance was identified. Secondly, human hepatocellular carcinoma cells (HepG2 were grown in a high-glucose medium and incubated with either 1-dairy proteins: whey, caseins, and a mixture of whey and casein; and 2-four amino acids (AA or mixtures of AA. The expression of GCK-related genes insulin receptor substrate-1 (IRS-1 and fatty acid synthase (FASN was increased with whey protein isolate or hydrolysate. Individually, leucine increased IRS-1 expression, whereas isoleucine and valine decreased FASN expression. A branched-chain AA mixture decreased IRS-1 and FASN expression. In conclusion, carriers of the A allele for rs1799884 in the GCK gene may benefit from a higher intake of dairy products to maintain optimal insulin sensitivity. Moreover, the results show that whey proteins affect the expression of genes related to glucose metabolism.

  5. Susceptibility of glucokinase-MODY mutants to inactivation by oxidative stress in pancreatic β-cells.

    Science.gov (United States)

    Cullen, Kirsty S; Matschinsky, Franz M; Agius, Loranne; Arden, Catherine

    2011-12-01

    The posttranslational regulation of glucokinase (GK) differs in hepatocytes and pancreatic β-cells. We tested the hypothesis that GK mutants that cause maturity-onset diabetes of the young (GK-MODY) show compromised activity and posttranslational regulation in β-cells. Activity and protein expression of GK-MODY and persistent hyperinsulinemic hypoglycemia of infancy (PHHI) mutants were studied in β-cell (MIN6) and non-β-cell (H4IIE) models. Binding of GK to phosphofructo-2-kinase, fructose-2,6-bisphosphatase (PFK2/FBPase2) was studied by bimolecular fluorescence complementation in cell-based models. Nine of 11 GK-MODY mutants that have minimal effect on enzyme kinetics in vitro showed decreased specific activity relative to wild type when expressed in β-cells. A subset of these were stable in non-β-cells but showed increased inactivation in conditions of oxidative stress and partial reversal of inactivation by dithiothreitol. Unlike the GK-MODY mutants, four of five GK-PHHI mutants had similar specific activity to wild type and Y214C had higher activity than wild type. The GK-binding protein PFK2/FBPase2 protected wild-type GK from oxidative inactivation and the decreased stability of GK-MODY mutants correlated with decreased interaction with PFK2/FBPase2. Several GK-MODY mutants show posttranslational defects in β-cells characterized by increased susceptibility to oxidative stress and/or protein instability. Regulation of GK activity through modulation of thiol status may be a physiological regulatory mechanism for the control of GK activity in β-cells.

  6. Glucokinase gene mutations: structural and genotype-phenotype analyses in MODY children from South Italy.

    Directory of Open Access Journals (Sweden)

    Nadia Tinto

    Full Text Available BACKGROUND: Maturity onset diabetes of the young type 2 (or GCK MODY is a genetic form of diabetes mellitus provoked by mutations in the glucokinase gene (GCK. METHODOLOGY/PRINCIPAL FINDINGS: We screened the GCK gene by direct sequencing in 30 patients from South Italy with suspected MODY. The mutation-induced structural alterations in the protein were analyzed by molecular modeling. The patients' biochemical, clinical and anamnestic data were obtained. Mutations were detected in 16/30 patients (53%; 9 of the 12 mutations identified were novel (p.Glu70Asp, p.Phe123Leu, p.Asp132Asn, p.His137Asp, p.Gly162Asp, p.Thr168Ala, p.Arg392Ser, p.Glu290X, p.Gln106_Met107delinsLeu and are in regions involved in structural rearrangements required for catalysis. The prevalence of mutation sites was higher in the small domain (7/12: approximately 59% than in the large (4/12: 33% domain or in the connection (1/12: 8% region of the protein. Mild diabetic phenotypes were detected in almost all patients [mean (SD OGTT = 7.8 mMol/L (1.8] and mean triglyceride levels were lower in mutated than in unmutated GCK patients (p = 0.04. CONCLUSIONS: The prevalence of GCK MODY is high in southern Italy, and the GCK small domain is a hot spot for MODY mutations. Both the severity of the GCK mutation and the genetic background seem to play a relevant role in the GCK MODY phenotype. Indeed, a partial genotype-phenotype correlation was identified in related patients (3 pairs of siblings but not in two unrelated children bearing the same mutation. Thus, the molecular approach allows the physician to confirm the diagnosis and to predict severity of the mutation.

  7. Lactose metabolism in Streptococcus lactis: studies with a mutant lacking glucokinase and mannose-phosphotransferase activities

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, J.; Chassy, B.M.; Egan, W.

    1985-04-01

    A mutant of Streptococcus lactis 133 has been isolated that lacks both glucokinase and phosphoenolpyruvate-dependent mannose- phosphotransferase (mannose-PTS) activities. The double mutant S. lactis 133 mannose-PTSd GK- is unable to utilize either exogenously supplied or intracellularly generated glucose for growth. Fluorographic analyses of metabolites formed during the metabolism of (/sup 14/C)lactose labeled specifically in the glucose or galactosyl moiety established that the cells were unable to phosphorylate intracellular glucose. However, cells of S. lactis 133 mannose-PTSd GK- readily metabolized intracellular glucose 6-phosphate, and the growth rates and cell yield of the mutant and parental strains on sucrose were the same. During growth on lactose, S. lactis 133 mannose-PTSd GK- fermented only the galactose moiety of the disaccharide, and 1 mol of glucose was generated per mol of lactose consumed. For an equivalent concentration of lactose, the cell yield of the mutant was 50% that of the wild type. The specific rate of lactose utilization by growing cells of S. lactis 133 mannose-PTSd GK- was ca. 50% greater than that of the wild type, but the cell doubling times were 70 and 47 min, respectively. High-resolution /sup 31/P nuclear magnetic resonance studies of lactose transport by starved cells of S. lactis 133 and S. lactis 133 mannose-PTSd GK- showed that the latter cells contained elevated lactose-PTS activity. Throughout exponential growth on lactose, the mutant maintained an intracellular steady-state glucose concentration of 100 mM.

  8. Biochemical and biophysical investigations of the interaction between human glucokinase and pro-apoptotic BAD.

    Science.gov (United States)

    Rexford, Alix; Zorio, Diego A R; Miller, Brian G

    2017-01-01

    The glycolytic enzyme glucokinase (GCK) and the pro-apoptotic protein BAD reportedly reside within a five-membered complex that localizes to the mitochondria of mammalian hepatocytes and pancreatic β-cells. Photochemical crosslinking studies using a synthetic analog of BAD's BH3 domain and in vitro transcription/translation experiments support a direct interaction between BAD and GCK. To investigate the biochemical and biophysical consequences of the BAD:GCK interaction, we developed a method for the production of recombinant human BAD. Consistent with published reports, recombinant BAD displays high affinity for Bcl-xL (KD = 7 nM), and phosphorylation of BAD at S118, within the BH3 domain, abolishes this interaction. Unexpectedly, we do not detect association of recombinant, full-length BAD with recombinant human pancreatic GCK over a range of protein concentrations using various biochemical methods including size-exclusion chromatography, chemical cross-linking, analytical ultracentrifugation, and isothermal titration calorimetry. Furthermore, fluorescence polarization assays and isothermal titration calorimetry detect no direct interaction between GCK and BAD BH3 peptides. Kinetic characterization of GCK in the presence of high concentrations of recombinant BAD show modest (BAD BH3 peptides. These results raise questions as to the mechanism of action of stapled peptide analogs modeled after the BAD BH3 domain, which reportedly enhance the Vmax value of GCK and stimulate insulin release in BAD-deficient islets. Based on our results, we postulate that the BAD:GCK interaction, and any resultant regulatory effect(s) upon GCK activity, requires the participation of additional members of the mitochondrial complex.

  9. Lactose metabolism in Streptococcus lactis: studies with a mutant lacking glucokinase and mannose-phosphotransferase activities

    International Nuclear Information System (INIS)

    Thompson, J.; Chassy, B.M.; Egan, W.

    1985-01-01

    A mutant of Streptococcus lactis 133 has been isolated that lacks both glucokinase and phosphoenolpyruvate-dependent mannose- phosphotransferase (mannose-PTS) activities. The double mutant S. lactis 133 mannose-PTSd GK- is unable to utilize either exogenously supplied or intracellularly generated glucose for growth. Fluorographic analyses of metabolites formed during the metabolism of [ 14 C]lactose labeled specifically in the glucose or galactosyl moiety established that the cells were unable to phosphorylate intracellular glucose. However, cells of S. lactis 133 mannose-PTSd GK- readily metabolized intracellular glucose 6-phosphate, and the growth rates and cell yield of the mutant and parental strains on sucrose were the same. During growth on lactose, S. lactis 133 mannose-PTSd GK- fermented only the galactose moiety of the disaccharide, and 1 mol of glucose was generated per mol of lactose consumed. For an equivalent concentration of lactose, the cell yield of the mutant was 50% that of the wild type. The specific rate of lactose utilization by growing cells of S. lactis 133 mannose-PTSd GK- was ca. 50% greater than that of the wild type, but the cell doubling times were 70 and 47 min, respectively. High-resolution 31 P nuclear magnetic resonance studies of lactose transport by starved cells of S. lactis 133 and S. lactis 133 mannose-PTSd GK- showed that the latter cells contained elevated lactose-PTS activity. Throughout exponential growth on lactose, the mutant maintained an intracellular steady-state glucose concentration of 100 mM

  10. Order-disorder transitions govern kinetic cooperativity and allostery of monomeric human glucokinase.

    Directory of Open Access Journals (Sweden)

    Mioara Larion

    Full Text Available Glucokinase (GCK catalyzes the rate-limiting step of glucose catabolism in the pancreas, where it functions as the body's principal glucose sensor. GCK dysfunction leads to several potentially fatal diseases including maturity-onset diabetes of the young type II (MODY-II and persistent hypoglycemic hyperinsulinemia of infancy (PHHI. GCK maintains glucose homeostasis by displaying a sigmoidal kinetic response to increasing blood glucose levels. This positive cooperativity is unique because the enzyme functions exclusively as a monomer and possesses only a single glucose binding site. Despite nearly a half century of research, the mechanistic basis for GCK's homotropic allostery remains unresolved. Here we explain GCK cooperativity in terms of large-scale, glucose-mediated disorder-order transitions using 17 isotopically labeled isoleucine methyl groups and three tryptophan side chains as sensitive nuclear magnetic resonance (NMR probes. We find that the small domain of unliganded GCK is intrinsically disordered and samples a broad conformational ensemble. We also demonstrate that small-molecule diabetes therapeutic agents and hyperinsulinemia-associated GCK mutations share a strikingly similar activation mechanism, characterized by a population shift toward a more narrow, well-ordered ensemble resembling the glucose-bound conformation. Our results support a model in which GCK generates its cooperative kinetic response at low glucose concentrations by using a millisecond disorder-order cycle of the small domain as a "time-delay loop," which is bypassed at high glucose concentrations, providing a unique mechanism to allosterically regulate the activity of human GCK under physiological conditions.

  11. Phosphorylation of Staphylococcus aureus Protein-Tyrosine Kinase Affects the Function of Glucokinase and Biofilm Formation.

    Science.gov (United States)

    Vasu, Dudipeta; Kumar, Pasupuleti Santhosh; Prasad, Uppu Venkateswara; Swarupa, Vimjam; Yeswanth, Sthanikam; Srikanth, Lokanathan; Sunitha, Manne Mudhu; Choudhary, Abhijith; Sarma, Potukuchi Venkata Gurunadha Krishna

    2017-03-01

    When Staphylococcus aureus is grown in the presence of high concentration of external glucose, this sugar is phosphorylated by glucokinase (glkA) to form glucose-6-phosphate. This product subsequently enters into anabolic phase, which favors biofilm formation. The presence of ROK (repressor protein, open reading frame, sugar kinase) motif, phosphate-1 and -2 sites, and tyrosine kinase sites in glkA of S. aureus indicates that phosphorylation must regulate the glkA activity. The aim of the present study was to identify the effect of phosphorylation on the function of S. aureus glkA and biofilm formation. Pure glkA and protein-tyrosine kinase (BYK) of S. aureus ATCC 12600 were obtained by fractionating the cytosolic fractions of glkA1 and BYK-1 expressing recombinant clones through nickel metal chelate column. The pure glkA was used as a substrate for BYK and the phosphorylation of glkA was confirmed by treating with reagent A and resolving in SDS-PAGE, as well as staining with reagent A. The kinetic parameters of glkA and phosphorylated glkA were determined spectrophotometrically, and in silico tools were used for validation. S. aureus was grown in brain heart infusion broth, which was supplemented with glucose, and then biofilm units were calculated. Fourfold elevated glkA activity was observed upon the phosphorylation by BYK. Protein-protein docking analysis revealed that glkA structure docked close to the adenosine triphosphate-binding site of BYK structure corroborating the kinetic results. Further, S. aureus grown in the presence of elevated glucose concentration exhibited an increase in the rate of biofilm formation. The elevated function of glkA is an essential requirement for increased biofilm units in S. aureus, a key pathogenic factor that helps its survival and spread the infection.

  12. Rare Sugar Syrup Containing d-Allulose but Not High-Fructose Corn Syrup Maintains Glucose Tolerance and Insulin Sensitivity Partly via Hepatic Glucokinase Translocation in Wistar Rats.

    Science.gov (United States)

    Shintani, Tomoya; Yamada, Takako; Hayashi, Noriko; Iida, Tetsuo; Nagata, Yasuo; Ozaki, Nobuaki; Toyoda, Yukiyasu

    2017-04-05

    Ingestion of high-fructose corn syrup (HFCS) is associated with the risk of both diabetes and obesity. Rare sugar syrup (RSS) has been developed by alkaline isomerization of HFCS and has anti-obesity and anti-diabetic effects. However, the influence of RSS on glucose metabolism has not been explored. We investigated whether long-term administration of RSS maintains glucose tolerance and whether the underlying mechanism involves hepatic glucokinase translocation. Wistar rats were administered water, RSS, or HFCS in drinking water for 10 weeks and then evaluated for glucose tolerance, insulin tolerance, liver glycogen content, and subcellular distribution of liver glucokinase. RSS significantly suppressed body weight gain and abdominal fat mass (p glucose tolerance test revealed significantly higher blood glucose levels in the HFCS group compared to the water group, whereas the RSS group had significantly lower blood glucose levels from 90 to 180 min (p water group (p glucose loading, the nuclear export of glucokinase was significantly increased in the RSS group compared to the water group. These results imply that RSS maintains glucose tolerance and insulin sensitivity, at least partly, by enhancing nuclear export of hepatic glucokinase.

  13. Phenotype Heterogeneity in Glucokinase-Maturity-Onset Diabetes of the Young (GCK-MODY) Patients.

    Science.gov (United States)

    Wędrychowicz, Anna; Tobór, Ewa; Wilk, Magdalena; Ziółkowska-Ledwith, Ewa; Rams, Anna; Wzorek, Katarzyna; Sabal, Barbara; Stelmach, Małgorzata; Starzyk, Jerzy B

    2017-09-01

    The aim of the study was to evaluate the clinical phenotypes of glucokinase-maturity-onset diabetes of the young (GCK-MODY) pediatric patients from Southwest Poland and to search for phenotype-genotype correlations. We conducted a retrospective analysis of data on 37 CGK-MODY patients consisting of 21 girls and 16 boys of ages 1.9-20.1 (mean 12.5±5.2) years, treated in our centre in the time period between 2002 and 2013. GCK-MODY carriers were found in a frequency of 3% among 1043 diabetes mellitus (DM) patients and constituted the second most numerous group of DM patients, following type 1 DM, in our centre. The mean age of GCK-MODY diagnosis was 10.4±4.5 years. The findings leading to the diagnosis were impaired fasting glucose (IFG) (15/37), symptoms of hyperglycemia (4/37), and a GCK-MODY family history (18/37). Mean fasting blood glucose level was 6.67±1.64 mmol/L. In the sample, there were patients with normal values (4/37), those with DM (10/37), and IFG (23/37). In OGTT, 120 min glucose level was normal in 8, diabetic in 2, and characteristic for glucose intolerance in 27 of the 37 cases. Twelve of the 37 cases (32%) were identified as GCK-MODY carriers. In the total group, mean C-peptide level was 2.13±0.65 ng/mL and HbA1c was 6.26±0.45% (44.9±-18 mmol/mol). Thirty-two patients had a family history of DM. DM autoantibodies were detected in two patients. The most common mutations were p.Gly318Arg (11/37) and p.Val302Leu (8/37). There was no correlation between type of mutations and plasma glucose levels. The phenotype of GCK-MODY patients may vary from those characteristic for other DM types to an asymptomatic state with normal FG with no correlation with genotype.

  14. Identification and functional characterisation of novel glucokinase mutations causing maturity-onset diabetes of the young in Slovakia.

    Directory of Open Access Journals (Sweden)

    Lucia Valentínová

    Full Text Available Heterozygous glucokinase (GCK mutations cause a subtype of maturity-onset diabetes of the young (GCK-MODY. Over 600 GCK mutations have been reported of which ∼65% are missense. In many cases co-segregation has not been established and despite the importance of functional studies in ascribing pathogenicity for missense variants these have only been performed for C, c.1113-1114delGC were novel. Parental DNA was available for 22 probands (covering 14/22 mutations and co-segregation established in all cases. Bioinformatic analysis predicted all missense mutations to be damaging. Nine (I110N, V200A, N204D, G223S, G258R, F419S, V244G, L315H, I436N mutations were functionally evaluated. Basic kinetic analysis explained pathogenicity for 7 mutants which showed reduced glucokinase activity with relative activity indices (RAI between 0.6 to <0.001 compared to wild-type GCK (1.0. For the remaining 2 mutants additional molecular mechanisms were investigated. Differences in glucokinase regulatory protein (GKRP -mediated-inhibition of GCK were observed for both L315H & I436N when compared to wild type (IC(50 14.6±0.1 mM & 20.3±1.6 mM vs.13.3±0.1 mM respectively [p<0.03]. Protein instability as assessed by thermal lability studies demonstrated that both L315H and I436N show marked thermal instability compared to wild-type GCK (RAI at 55°C 8.8±0.8% & 3.1±0.4% vs. 42.5±3.9% respectively [p<0.001]. The minimum prevalence of GCK-MODY amongst Slovakian patients with diabetes was 0.03%. In conclusion, we have identified 22 GCK mutations in 36 Slovakian probands and demonstrate that combining family, bioinformatic and functional studies can aid the interpretation of variants identified by molecular diagnostic screening.

  15. Identification of Maturity-Onset Diabetes of the Young Caused by Glucokinase Mutations Detected Using Whole-Exome Sequencing

    Directory of Open Access Journals (Sweden)

    Eun-Hee Cho

    2017-05-01

    Full Text Available Glucokinase maturity-onset diabetes of the young (GCK-MODY represents a distinct subgroup of MODY that does not require hyperglycemia-lowering treatment and has very few diabetes-related complications. Three patients from two families who presented with clinical signs of GCK-MODY were evaluated. Whole-exome sequencing was performed and the effects of the identified mutations were assessed using bioinformatics tools, such as PolyPhen-2, SIFT, and in silico modeling. We identified two mutations: p.Leu30Pro and p.Ser383Leu. In silico analyses predicted that these mutations result in structural conformational changes, protein destabilization, and thermal instability. Our findings may inform future GCK-MODY diagnosis; furthermore, the two mutations detected in two Korean families with GCK-MODY improve our understanding of the genetic basis of the disease.

  16. Rosiglitazone stimulates the release and synthesis of insulin by enhancing GLUT-2, glucokinase and BETA2/NeuroD expression

    International Nuclear Information System (INIS)

    Kim, Hyo-Sup; Noh, Jung-Hyun; Hong, Seung-Hyun; Hwang, You-Cheol; Yang, Tae-Young; Lee, Myung-Shik; Kim, Kwang-Won; Lee, Moon-Kyu

    2008-01-01

    Peroxisome proliferator-activated receptor (PPAR)-γ is a member of the nuclear receptor superfamily, and its ligands, the thiazolidinediones, might directly stimulate insulin release and insulin synthesis in pancreatic β-cells. In the present study, we examined the effects of rosiglitazone (RGZ) on insulin release and synthesis in pancreatic β-cell (INS-1). Insulin release and synthesis were stimulated by treatment with RGZ for 24 h. RGZ upregulated the expressions of GLUT-2 and glucokinase (GCK). Moreover, it was found that RGZ increased the expression of BETA2/NeuroD gene which could regulate insulin gene expression. These results suggest that RGZ could stimulate the release and synthesis of insulin through the upregulation of GLUT-2, GCK, and BETA2/NeuroD gene expression

  17. Genetic and clinical characteristics of Chinese children with Glucokinase-maturity-onset diabetes of the young (GCK-MODY).

    Science.gov (United States)

    Li, Xiuzhen; Ting, Tzer Hwu; Sheng, Huiying; Liang, Cui Li; Shao, Yongxian; Jiang, Minyan; Xu, Aijing; Lin, Yunting; Liu, Li

    2018-03-06

    There is scarcity of information on the clinical features and genetics of glucokinase-maturity-onset diabetes of the young (GCK-MODY) in China. The aim of the study was to investigate the clinical and molecular characteristics of Chinese children with GCK-MODY. Eleven children with asymptomatic hyperglycemia and clinically suspected GCK-MODY were identified from the database of children with diabetes in the biggest children's hospital in South China. Clinical data were obtained from medical records. Blood was collected from the patients and their parents for glucokinase (GCK) gene analysis. Parents without diabetes were tested for fasting glucose and HbA1c. Clinical information and blood for GCK gene analysis were obtained from grandparents with diabetes. GCK gene mutational analysis was performed by polymerase chain reaction and direct sequencing. Patients without a GCK gene mutation were screened by targeted next-generation sequencing (NGS) technology for other MODY genes. Nine children tested positive for GCK gene mutations while two were negative. The nine GCK-MODY patients were from unrelated families, aged 1 month to 9 years and 1 month at first detection of hyperglycaemia. Fasting glucose was elevated (6.1-8.5 mmol/L), HbA1c 5.2-6.7% (33.3-49.7 mmol/mol), both remained stable on follow-up over 9 months to 5 years. Five detected mutations had been previously reported: p.Val182Met, c.679 + 1G > A, p.Gly295Ser, p.Arg191Gln and p.Met41Thr. Four mutations were novel: c.483 + 2 T > A, p.Ser151del, p.Met57GlyfsX29 and p.Val374_Ala377del. No mutations were identified in the other two patients, who were also tested by NGS. GCK gene mutations are detected in Chinese children and their family members with typical clinical features of GCK-MODY. Four novel mutations are detected.

  18. A review of maturity onset diabetes of the young (MODY) and challenges in the management of glucokinase-MODY.

    Science.gov (United States)

    Bishay, Ramy H; Greenfield, Jerry R

    2016-11-21

    Maturity onset diabetes of the young (MODY), the most common monogenic form of diabetes, accounts for 1-2% of all diabetes diagnoses. Glucokinase (GCK)-MODY (also referred to as MODY2) constitutes 10-60% of all MODY cases and is inherited as an autosomal dominant heterozygous mutation, resulting in loss of function of the GCK gene. Patients with GCK-MODY generally have mild, fasting hyperglycaemia that is present from birth, are commonly leaner and diagnosed at a younger age than patients with type 2 diabetes, and rarely develop complications from diabetes. Hence, treatment is usually unnecessary and may be ceased. Therefore, genetic screening is recommended in all young patients (MODY, such as hepatocyte nuclear factor 1A mutations (MODY3) where hyperglycaemia is managed with low dose sulfonylurea rather than insulin. Patients with GCK-MODY, in line with trends in the general population, are becoming older and more overweight and obese, and are concomitantly developing features of insulin resistance and glucose intolerance. Therefore, controversy exists as to whether such "treatment-exempt" patients should be reassessed for treatment later in life. As testing becomes more accessible, clinicians and patients are likely to embrace genetic screening earlier in the course of diabetes, which may avert the consequences of delayed testing years after diagnosis and treatment initiation.

  19. Common variant in the glucokinase regulatory gene rs780094 and risk of nonalcoholic fatty liver disease: a meta-analysis.

    Science.gov (United States)

    Zain, Shamsul Mohd; Mohamed, Zahurin; Mohamed, Rosmawati

    2015-01-01

    Although studies have suggested that rs780094, a common variant in the glucokinase regulatory (GCKR) gene to be associated with type 2 diabetes, obesity, and their related traits, the genetic basis of the association between GCKR rs780094 and nonalcoholic fatty liver disease (NAFLD) is still being examined. This meta-analysis was performed to evaluate the effect strength caused by GCKR rs780094 on NAFLD. We searched Medline, PubMed, Scopus, and Embase for relevant articles published up to April 2014. Data were extracted, and summary estimates of the association between GCKR rs780094 and NAFLD were examined. Heterogeneity and publication bias were also examined. This meta-analysis incorporated a total of 2091 NAFLD cases and 3003 controls from five studies. Overall, the pooled result indicated that the GCKR rs780094 was significantly associated with increased risk of NAFLD (additive: odds ratio (OR) 1.25, 95% confidence interval (CI) 1.14-1.36, P risk of NAFLD. Similar effect size was demonstrated in both Asian and non-Asian populations. © 2014 Journal of Gastroenterology and Hepatology Foundation and Wiley Publishing Asia Pty Ltd.

  20. Evidence for the Presence of Glucosensor Mechanisms Not Dependent on Glucokinase in Hypothalamus and Hindbrain of Rainbow Trout (Oncorhynchus mykiss.

    Directory of Open Access Journals (Sweden)

    Cristina Otero-Rodiño

    Full Text Available We hypothesize that glucosensor mechanisms other than that mediated by glucokinase (GK operate in hypothalamus and hindbrain of the carnivorous fish species rainbow trout and stress affected them. Therefore, we evaluated in these areas changes in parameters which could be related to putative glucosensor mechanisms based on liver X receptor (LXR, mitochondrial activity, sweet taste receptor, and sodium/glucose co-transporter 1 (SGLT-1 6 h after intraperitoneal injection of 5 mL x Kg(-1 of saline solution alone (normoglycaemic treatment or containing insulin (hypoglycaemic treatment, 4 mg bovine insulin x Kg(-1 body mass, or D-glucose (hyperglycaemic treatment, 500 mg x Kg(-1 body mass. Half of tanks were kept at a 10 Kg fish mass x m(-3 and denoted as fish under normal stocking density (NSD whereas the remaining tanks were kept at a stressful high stocking density (70 kg fish mass x m(-3 denoted as HSD. The results obtained in non-stressed rainbow trout provide evidence, for the first time in fish, that manipulation of glucose levels induce changes in parameters which could be related to putative glucosensor systems based on LXR, mitochondrial activity and sweet taste receptor in hypothalamus, and a system based on SGLT-1 in hindbrain. Stress altered the response of parameters related to these systems to changes in glycaemia.

  1. Analysis of upstream promoter region and corresponding 5’ UTR of glucokinase (GCK gene in horse breeds

    Directory of Open Access Journals (Sweden)

    L. Minieri

    2010-04-01

    Full Text Available A region of glucokinase (GCK gene was sequenced in 14 horses of 14 different breeds. The resulting GCK nucleotide sequence (GenBank number EF136885 showed 77% homology with human GCK gene portion containing the upstream promoter region and the corresponding 5’ UTR of the exon 1. Conserved regulatory sequences near the putative transcriptional start site were identified. The obtained sequences were aligned to detect polymorphism. A new C>T transition within the 5’ UTR of exon 1 was found. Allele frequencies of this polymorphism were studied by PCR-RFLP in 193 horses of 14 breeds (Bardigiano, 21; Esperia Pony, 5; Haflinger, 10; Italian Heavy Draught Horse, 28; Italian Saddle, 25; Italian Trotter, 16; Lipizzan, 12; Maremmano, 15; Murgese, 14; Norico, 10; Salernitano, 12; Thoroughbred, 10; Tolfetano, 7 and Ventasso Horse, 8. The polymorphism was found in all breeds and differences in allelic frequencies among the breeds were observed. The new SNP identified within a regulative region of GCK gene, which plays an important role in insulin secretion and feeding behaviour, could be used for association studies with performance traits of the horses.

  2. The glucokinase mutation p.T206P is common among MODY patients of Jewish Ashkenazi descent.

    Science.gov (United States)

    Gozlan, Yael; Tenenbaum, Ariel; Shalitin, Shlomit; Lebenthal, Yael; Oron, Tal; Cohen, Ohad; Phillip, Moshe; Gat-Yablonski, Galia

    2012-09-01

    Maturity-onset diabetes of the young (MODY) is characterized by an autosomal dominant mode of inheritance; a primary defect in insulin secretion with non-ketotic hyperglycemia, age of onset under 25 yr; and lack of autoantibodies. Heterozygous mutations in glucokinase (GCK) are associated with mild fasting hyperglycemia and gestational diabetes mellitus while homozygous or compound heterozygous GCK mutations result in permanent neonatal diabetes mellitus. Given that both the Israeli-Arabic and the various Israeli-Jewish communities tend to maintain ethnic seclusion, we speculated that it would be possible to identify a relatively narrow spectrum of mutations in the Israeli population. To characterize the genetic basis of GCK-MODY in the different ethnic groups of the Israeli population. Patients with clinically identified GCK-MODY and their first degree family members. Molecular analysis of GCK was performed on genomic DNA using polymerase chain reaction, denaturing gradient gel electrophoresis (DGGE), and sequencing. Bioinformatic model was preformed using the NEST program. Mutations in GCK were identified in 25 families and were all family-specific, except c.616A>C. p.T206P. This mutation was identified in six unrelated families, all patients from a Jewish-Ashkenazi descent, thus indicating an ethno-genetic correlation. A simple, fast, and relatively cheap DGGE/restriction-digestion assay was developed. The high incidence of the mutant allele in GCK-MODY patients of Jewish-Ashkenazi descent suggests a founder effect. We propose that clinically identified GCK-MODY patients of Jewish-Ashkenazi origin be first tested for this mutation. © 2011 John Wiley & Sons A/S.

  3. Molecular and clinical characterization of glucokinase maturity-onset diabetes of the young (GCK-MODY) in Japanese patients.

    Science.gov (United States)

    Kawakita, R; Hosokawa, Y; Fujimaru, R; Tamagawa, N; Urakami, T; Takasawa, K; Moriya, K; Mizuno, H; Maruo, Y; Takuwa, M; Nagasaka, H; Nishi, Y; Yamamoto, Y; Aizu, K; Yorifuji, T

    2014-11-01

    To investigate the molecular and clinical characteristics of the largest series of Japanese patients with glucokinase maturity-onset diabetes of the young (GCK-MODY), and to find any features specific to Asian people. We enrolled 78 Japanese patients with GCK-MODY from 41 families (55 probands diagnosed at the age of 0-14 years and their 23 adult family members). Mutations were identified by direct sequencing or multiplex ligation-dependent probe amplification of all exons of the GCK gene. Detailed clinical and laboratory data were collected on the probands using questionnaires, which were sent to the treating physicians. Data on current clinical status and HbA1c levels were also collected from adult patients. A total of 35 different mutations were identified, of which seven were novel. Fasting blood glucose and HbA1c levels of the probands were ≤9.3 mmol/l and ≤56 mmol/mol (7.3%), respectively, and there was considerable variation in their BMI percentiles (0.4-96.2). In total, 25% of the probands had elevated homeostatic assessment of insulin resistance values, and 58.3% of these had evidence of concomitant Type 2 diabetes in their family. The HbA1c levels for adults were slightly higher, up to 61 mmol/mol (7.8%). The incidence of microvascular complications was low. Out of these 78 people with GCK-MODY and 40 additional family members with hyperglycaemia whose genetic status was unknown, only one had diabetic nephropathy. The molecular and clinical features of GCK-MODY in Japanese people are similar to those of other ethnic populations; however, making a diagnosis of GCK-MODY was more challenging in patients with signs of insulin resistance. © 2014 The Authors. Diabetic Medicine © 2014 Diabetes UK.

  4. Glucokinase regulatory protein genetic variant interacts with omega-3 PUFA to influence insulin resistance and inflammation in metabolic syndrome.

    Directory of Open Access Journals (Sweden)

    Pablo Perez-Martinez

    Full Text Available Glucokinase Regulatory Protein (GCKR plays a central role regulating both hepatic triglyceride and glucose metabolism. Fatty acids are key metabolic regulators, which interact with genetic factors and influence glucose metabolism and other metabolic traits. Omega-3 polyunsaturated fatty acids (n-3 PUFA have been of considerable interest, due to their potential to reduce metabolic syndrome (MetS risk.To examine whether genetic variability at the GCKR gene locus was associated with the degree of insulin resistance, plasma concentrations of C-reactive protein (CRP and n-3 PUFA in MetS subjects.Homeostasis model assessment of insulin resistance (HOMA-IR, HOMA-B, plasma concentrations of C-peptide, CRP, fatty acid composition and the GCKR rs1260326-P446L polymorphism, were determined in a cross-sectional analysis of 379 subjects with MetS participating in the LIPGENE dietary cohort.Among subjects with n-3 PUFA levels below the population median, carriers of the common C/C genotype had higher plasma concentrations of fasting insulin (P = 0.019, C-peptide (P = 0.004, HOMA-IR (P = 0.008 and CRP (P = 0.032 as compared with subjects carrying the minor T-allele (Leu446. In contrast, homozygous C/C carriers with n-3 PUFA levels above the median showed lower plasma concentrations of fasting insulin, peptide C, HOMA-IR and CRP, as compared with individuals with the T-allele.We have demonstrated a significant interaction between the GCKR rs1260326-P446L polymorphism and plasma n-3 PUFA levels modulating insulin resistance and inflammatory markers in MetS subjects. Further studies are needed to confirm this gene-diet interaction in the general population and whether targeted dietary recommendations can prevent MetS in genetically susceptible individuals.ClinicalTrials.gov NCT00429195.

  5. TMG-123, a novel glucokinase activator, exerts durable effects on hyperglycemia without increasing triglyceride in diabetic animal models.

    Science.gov (United States)

    Tsumura, Yoshinori; Tsushima, Yu; Tamura, Azusa; Hasebe, Makiko; Kanou, Masanobu; Kato, Hirotsugu; Kobayashi, Tsunefumi

    2017-01-01

    Glucokinase (GK) plays a critical role for maintaining glucose homeostasis with regulating glucose uptake in liver and insulin secretion in pancreas. GK activators have been reported to decrease blood glucose levels in patients with type 2 diabetes mellitus. However, clinical development of GK activators has failed due to the loss of glucose-lowering effects and increased plasma triglyceride levels after chronic treatment. Here, we generated a novel GK activator, TMG-123, examined its in vitro and in vivo pharmacological characteristics, and evaluated its risks of aforementioned clinical issues. TMG-123 selectively activated GK enzyme activity without increasing Vmax. TMG-123 improved glucose tolerance without increasing plasma insulin levels in both insulin-deficient (Goto-Kakizaki rats) and insulin-resistant (db/db mice) models. The beneficial effect on glucose tolerance was greater than results observed with clinically available antidiabetic drugs such as metformin and glibenclamide in Zucker Diabetic Fatty rats. TMG-123 also improved glucose tolerance in combination with metformin. After 4 weeks of administration, TMG-123 reduced the Hemoglobin A1c levels without affecting liver and plasma triglyceride levels in Goto-Kakizaki rats and Diet-Induced Obesity mice. Moreover, TMG-123 sustained its effect on Hemoglobin A1c levels even after 24 weeks of administration without affecting triglycerides. Taken together, these data indicate that TMG-123 exerts glucose-lowering effects in both insulin-deficient and -resistant diabetes, and sustains reduced Hemoglobin A1c levels without affecting hepatic and plasma triglycerides even after chronic treatment. Therefore, TMG-123 is expected to be an antidiabetic drug that overcomes the concerns previously reported with other GK activators.

  6. FoxO1 and HNF-4 are involved in regulation of hepatic glucokinase gene expression by resveratrol.

    Science.gov (United States)

    Ganjam, Goutham Kumar; Dimova, Elitsa Y; Unterman, Terry G; Kietzmann, Thomas

    2009-11-06

    Resveratrol, a polyphenol derived from grapes, exerts important effects on glucose and lipid metabolism, yet detailed mechanisms mediating these effects remain unknown. The liver plays a central role in energy homeostasis, and glucokinase (GK) is a key enzyme involved in glucose utilization. Resveratrol activates SIRT1 (sirtuin 1), which promotes deacetylation of the forkhead transcription factor FoxO1. Previously, we reported that FoxO1 can suppress and that HNF-4 can stimulate GK expression in the liver. Here, we examined the role of FoxO1 and HNF-4 in mediating resveratrol effects on liver GK expression. Resveratrol suppressed hepatic GK expression in vivo and in isolated hepatocytes, and knocking down FoxO1 with shRNAs disrupted this effect. Reporter gene, gel shift, supershift assay, and chromatin immunoprecipitation studies show that FoxO1 binds to the GK promoter and that the interplay between FoxO1 and HNF-4 within the GK promoter is essential for mediating the effects of resveratrol. Resveratrol promotes deacetylation of FoxO1 and enhances its recruitment to the FoxO-binding element. Conversely, resveratrol suppresses recruitment of HNF-4 to its binding site, and knockdown of FoxO1 blocks this effect of resveratrol. Coprecipitation and chromatin immunoprecipitation studies show that resveratrol enhances interaction between FoxO1 and HNF-4, reduces binding of HNF-4 to its own site, and promotes its recruitment to the FoxO site in a FoxO1-dependent manner. These results provide the first evidence that resveratrol represses GK expression via FoxO1 and that the interaction between FoxO1 and HNF-4 contributes to these effects of resveratrol.

  7. FoxO1 and HNF-4 Are Involved in Regulation of Hepatic Glucokinase Gene Expression by Resveratrol*

    Science.gov (United States)

    Ganjam, Goutham Kumar; Dimova, Elitsa Y.; Unterman, Terry G.; Kietzmann, Thomas

    2009-01-01

    Resveratrol, a polyphenol derived from grapes, exerts important effects on glucose and lipid metabolism, yet detailed mechanisms mediating these effects remain unknown. The liver plays a central role in energy homeostasis, and glucokinase (GK) is a key enzyme involved in glucose utilization. Resveratrol activates SIRT1 (sirtuin 1), which promotes deacetylation of the forkhead transcription factor FoxO1. Previously, we reported that FoxO1 can suppress and that HNF-4 can stimulate GK expression in the liver. Here, we examined the role of FoxO1 and HNF-4 in mediating resveratrol effects on liver GK expression. Resveratrol suppressed hepatic GK expression in vivo and in isolated hepatocytes, and knocking down FoxO1 with shRNAs disrupted this effect. Reporter gene, gel shift, supershift assay, and chromatin immunoprecipitation studies show that FoxO1 binds to the GK promoter and that the interplay between FoxO1 and HNF-4 within the GK promoter is essential for mediating the effects of resveratrol. Resveratrol promotes deacetylation of FoxO1 and enhances its recruitment to the FoxO-binding element. Conversely, resveratrol suppresses recruitment of HNF-4 to its binding site, and knockdown of FoxO1 blocks this effect of resveratrol. Coprecipitation and chromatin immunoprecipitation studies show that resveratrol enhances interaction between FoxO1 and HNF-4, reduces binding of HNF-4 to its own site, and promotes its recruitment to the FoxO site in a FoxO1-dependent manner. These results provide the first evidence that resveratrol represses GK expression via FoxO1 and that the interaction between FoxO1 and HNF-4 contributes to these effects of resveratrol. PMID:19740748

  8. Toward a unified model of passive drug permeation II: the physiochemical determinants of unbound tissue distribution with applications to the design of hepatoselective glucokinase activators.

    Science.gov (United States)

    Ghosh, Avijit; Maurer, Tristan S; Litchfield, John; Varma, Manthema V; Rotter, Charles; Scialis, Renato; Feng, Bo; Tu, Meihua; Guimaraes, Cris R W; Scott, Dennis O

    2014-10-01

    In this work, we leverage a mathematical model of the underlying physiochemical properties of tissues and physicochemical properties of molecules to support the development of hepatoselective glucokinase activators. Passive distribution is modeled via a Fick-Nernst-Planck approach, using in vitro experimental data to estimate the permeability of both ionized and neutral species. The model accounts for pH and electrochemical potential across cellular membranes, ionization according to Henderson-Hasselbalch, passive permeation of the neutral species using Fick's law, and passive permeation of the ionized species using the Nernst-Planck equation. The mathematical model of the physiochemical system allows derivation of a single set of parameters governing the distribution of drug molecules across multiple conditions both in vitro and in vivo. A case study using this approach in the development of hepatoselective glucokinase activators via organic anion-transporting polypeptide-mediated hepatic uptake and impaired passive distribution to the pancreas is described. The results for these molecules indicate the permeability penalty of the ionized form is offset by its relative abundance, leading to passive pancreatic exclusion according to the Nernst-Planck extension of Fickian passive permeation. Generally, this model serves as a useful construct for drug discovery scientists to understand subcellular exposure of acids or bases using specific physiochemical properties. Copyright © 2014 by The American Society for Pharmacology and Experimental Therapeutics.

  9. Muscle insulin binding and plasma levels in relation to liver glucokinase activity, glucose metabolism and dietary carbohydrates in rainbow trout.

    Science.gov (United States)

    Capilla, Encarnación; Médale, Françoise; Navarro, Isabel; Panserat, Stéphane; Vachot, Christiane; Kaushik, Sadasivam; Gutiérrez, Joaquim

    2003-01-31

    Rainbow trout were fed for 10 weeks with either a carbohydrate-free diet (C-free) or with four experimental diets containing various levels (20 or 40%) and sources of starch (extruded wheat or peas) in order to examine metabolic utilisation of dietary vegetable carbohydrates and its endocrine control. The study was focused on the parameters described as limiting in glucose metabolism in fish. Feeding trials were conducted at 8 and 18 degrees C to establish whether carbohydrate-rich diets can be used in trout farming irrespective of water temperature. At both temperatures, pea diets (especially the highest level) resulted in a feed efficiency as high as the C-free diet. Fish had similar growth rates except when fed the low wheat content diet. Glycaemia values 6 h after feeding were significantly higher in trout fed carbohydrate diets than those given the C-free diet, whereas plasma insulin levels were similar independently of the levels of dietary starch. This study provides the first evidence that glucokinase (GK) activity and mRNA level in trout liver increase in proportion to the content of dietary starch. Nevertheless, these changes were not correlated with plasma insulin levels. Insulin-like growth factor-I (IGF-I) binding and number of receptors in skeletal muscle were consistently higher than those for insulin but no diet-induced differences were found for any of these parameters. Temperature clearly affected the postprandial profile of glucose and insulin, which both showed lower levels 6 h after feeding at 8 degrees C than at 18 degrees C, which was consistent with a lower feed intake. Glucose and insulin levels decreased markedly 24 h after feeding at 18 degrees C, while they were still high at 8 degrees C, an observation concordant with delayed transit rate. These findings indicate satisfactory adaptation of rainbow trout to diets with a relatively high vegetable starch content, especially when provided as extruded peas, and indicate that diets with

  10. Safety, tolerability, pharmacokinetics, and pharmacodynamics of novel glucokinase activator HMS5552: results from a first-in-human single ascending dose study

    Directory of Open Access Journals (Sweden)

    Xu HR

    2016-05-01

    Full Text Available Hongrong Xu,1,* Lei Sheng,1,* Weili Chen,1 Fei Yuan,1 Mengjie Yang,1 Hui Li,1 Xuening Li,1 John Choi,2 Guiyu Zhao,2 Tianxin Hu,2 Yongguo Li,2 Yi Zhang,2 Li Chen2 1Department of Clinical Pharmacology, Zhongshan Hospital, Fudan University, Shanghai, 2Department of Clinical Research & Development, Hua Medicine, Shanghai, People’s Republic of China *These authors have contributed equally to this work Background: HMS5552, a novel fourth-generation glucokinase (GK activator, has demonstrated promising effects on glycemic control in preclinical models of type 2 diabetes. This single ascending dose study was conducted to investigate the safety, tolerability, pharmacokinetics (PK, and pharmacodynamics (PD of HMS5552 during its first-in-human exposure.Methods: Sixty healthy subjects were enrolled. In each of six dose-cohorts (5, 10, 15, 25, 35, and 50 mg, ten subjects were randomized with eight subjects receiving the same cohort-dose of HMS5552 and two receiving placebo. Plasma HMS5552 exposure, glucose, and insulin were measured repeatedly during fasting and after a standardized meal. Assessment included safety, PK, and PD endpoints.Results: HMS5552 showed dose-proportional increases in area under the curve 0 to the last quantifiable concentration (AUC0–t and maximum plasma concentration (Cmax. Slopes estimated by linear regression for AUC0–t and Cmax were ~1.0 (0.932 and 0.933, respectively. Geometric mean elimination half-life ranged from 4.48 to 7.51 hours and apparent clearance ranged from 11.5 to 13.1 L/h across all doses. No significant sex effect was observed in PK parameters. HMS5552 also demonstrated dose-related PD responses in terms of maximum glucose change from baseline (% and mean glucose area under effect curve 0–4 hours change from baseline (% (P<0.001. Fifteen adverse events were reported by nine subjects (ten with HMS5552 and five with the placebo. All adverse events were mild in intensity and resolved without any treatment

  11. Functional Characterization of MODY2 Mutations Highlights the Importance of the Fine-Tuning of Glucokinase and Its Role in Glucose Sensing

    Science.gov (United States)

    García-Herrero, Carmen-María; Rubio-Cabezas, Oscar; Azriel, Sharona; Gutierrez-Nogués, Angel; Aragonés, Angel; Vincent, Olivier; Campos-Barros, Angel; Argente, Jesús; Navas, María-Angeles

    2012-01-01

    Glucokinase (GK) acts as a glucose sensor in the pancreatic beta-cell and regulates insulin secretion. Heterozygous mutations in the human GK-encoding GCK gene that reduce the activity index increase the glucose-stimulated insulin secretion threshold and cause familial, mild fasting hyperglycaemia, also known as Maturity Onset Diabetes of the Young type 2 (MODY2). Here we describe the biochemical characterization of five missense GK mutations: p.Ile130Thr, p.Asp205His, p.Gly223Ser, p.His416Arg and p.Ala449Thr. The enzymatic analysis of the corresponding bacterially expressed GST-GK mutant proteins show that all of them impair the kinetic characteristics of the enzyme. In keeping with their position within the protein, mutations p.Ile130Thr, p.Asp205His, p.Gly223Ser, and p.His416Arg strongly decrease the activity index of GK, affecting to one or more kinetic parameters. In contrast, the p.Ala449Thr mutation, which is located in the allosteric activator site, does not affect significantly the activity index of GK, but dramatically modifies the main kinetic parameters responsible for the function of this enzyme as a glucose sensor. The reduced Kcat of the mutant (3.21±0.28 s−1 vs 47.86±2.78 s−1) is balanced by an increased glucose affinity (S0.5 = 1.33±0.08 mM vs 7.86±0.09 mM) and loss of cooperativity for this substrate. We further studied the mechanism by which this mutation impaired GK kinetics by measuring the differential effects of several competitive inhibitors and one allosteric activator on the mutant protein. Our results suggest that this mutation alters the equilibrium between the conformational states of glucokinase and highlights the importance of the fine-tuning of GK and its role in glucose sensing. PMID:22291974

  12. Synthesis and biological evaluation of [11C]AZ12504948; a novel tracer for imaging of glucokinase in pancreas and liver

    International Nuclear Information System (INIS)

    Jahan, M.; Johnström, P.; Nag, S.; Takano, A.; Korsgren, O.; Johansson, L.; Halldin, C.; Eriksson, O.

    2015-01-01

    Introduction: Glucokinase (GK) is potentially a target for imaging of islets of Langerhans. Here we report the radiosynthesis and preclinical evaluation of the GK activator, [ 11 C]AZ12504948, for in vivo imaging of GK. Methods: [ 11 C]AZ12504948 was synthesized by O-methylation of the precursor, AZ125555620, using carbon-11 methyl iodide ([ 11 C]CH 3 I). Preclinical evaluation was performed by autoradiography (ARG) of human tissues and PET/CT studies in pig and non-human primate. Result: [ 11 C]AZ12504948 was produced in reproducible good radiochemical yield in 28–30 min. Radiochemical purity of the formulated product was > 98% for up to 2 h with specific radioactivities 855 ± 209 GBq/μmol (n = 8). The preclinical evaluation showed some specificity for GK in liver, but not in pancreas. Conclusion: [ 11 C]AZ12504948 images GK in liver, but the low specificity impedes the visualization of GK in pancreas. Improved target specificity is required for further progress using PET probes based on this class of GK activators

  13. Identifying Glucokinase Monogenic Diabetes in a Multiethnic Gestational Diabetes Mellitus Cohort: New Pregnancy Screening Criteria and Utility of HbA1c.

    Science.gov (United States)

    Rudland, Victoria L; Hinchcliffe, Marcus; Pinner, Jason; Cole, Stuart; Mercorella, Belinda; Molyneaux, Lynda; Constantino, Maria; Yue, Dennis K; Ross, Glynis P; Wong, Jencia

    2016-01-01

    Glucokinase monogenic diabetes (GCK-maturity-onset diabetes of the young [MODY]) should be differentiated from gestational diabetes mellitus (GDM) because management differs. New pregnancy-specific screening criteria (NSC) have been proposed to identify women who warrant GCK genetic testing. We tested NSC and HbA1c in a multiethnic GDM cohort and examined projected referrals for GCK testing. Using a GDM database, 63 of 776 women had a postpartum oral glucose tolerance test suggestive of GCK-MODY. Of these 63 women, 31 agreed to undergo GCK testing. NSC accuracy and HbA1c were examined. Projected referrals were calculated by applying the NSC to a larger GDM database (n = 4,415). Four of 31 women were confirmed as having GCK-MODY (prevalence ∼0.5-1/100 with GDM). The NSC identified all Anglo-Celtic women but did not identify one Indian woman. The NSC will refer 6.1% of GDM cases for GCK testing, with more Asian/Indian women referred despite lower disease prevalence. Antepartum HbA1c was not higher in those with GCK-MODY. The NSC performed well in Anglo-Celtic women. Ethnic-specific criteria should be explored. © 2016 by the American Diabetes Association. Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work is not altered.

  14. Doubling the referral rate of monogenic diabetes through a nationwide information campaign--update on glucokinase gene mutations in a Polish cohort.

    Science.gov (United States)

    Borowiec, M; Fendler, W; Antosik, K; Baranowska, A; Gnys, P; Zmyslowska, A; Malecki, M; Mlynarski, W

    2012-12-01

    In order to improve recruitment efficiency of patients with monogenic diabetes in Poland, in September 2010 a nationwide advertising campaign was launched to inform multiple target groups interested or participating in pediatric diabetologic care. Promotional actions aimed at informing physicians, patients, parents and educators were carried out through nationwide newspapers, medical and patient-developed websites and educational conference presentations. Recruitment efficiency was compared between September 2010 (publication of the first report on project's results) and the following 12 months. The number of families and patients referred to genetic screening was increased by 92% and 96% respectively nearly reaching the numbers recruited throughout the initial 4 years of the project. Participation of non-academic centers was also significantly increased from 2.3% to 7.5% (p = 0.0005). DNA sequencing and Multiplex Ligation-dependant Probe Amplification of the glucokinase gene resulted in finding 50 different mutations. Among those mutations, 19 were novel variants, which included: 17 missense mutations (predicted to be pathogenic according to bioinformatic analysis), 1 nonsense mutation and 1 mutation affecting a consensus intronic splice site. Advertising actions directed at increasing recruitment efficiency are a powerful and possibly neglected tool in screening for rare genetic disorders with a clinically defined phenotype. © 2011 John Wiley & Sons A/S. Published by Blackwell Publishing Ltd.

  15. Production of a mouse strain with impaired glucose tolerance by systemic heterozygous knockout of the glucokinase gene and its feasibility as a prediabetes model

    Science.gov (United States)

    SAITO, Mikako; KANEDA, Asako; SUGIYAMA, Tae; IIDA, Ryousuke; OTOKUNI, Keiko; KABURAGI, Misako; MATSUOKA, Hideaki

    2015-01-01

    Exon II of glucokinase (Gk) was deleted to produce a systemic heterozygous Gk knockout (Gk+/−) mouse. The relative expression levels of Gk in the heart, lung, liver, stomach, and pancreas in Gk+/− mice ranged from 0.41–0.68 versus that in wild (Gk+/+) mice. On the other hand, its expression levels in the brain, adipose tissue, and muscle ranged from 0.95–1.03, and its expression levels in the spleen and kidney were nearly zero. Gk knockout caused no remarkable off-target effect on the expression of 7 diabetes causing genes (Shp, Hnf1a, Hnf1b, Irs1, Irs2, Kir6.2, and Pdx1) in 10 organs. The glucose tolerance test was conducted to determine the blood glucose concentrations just after fasting for 24 h (FBG) and at 2 h after high-glucose application (GTT2h). The FBG-GTT2h plots obtained with the wild strain fed the control diet (CD), Gk+/− strain fed the CD, and Gk+/− strain fed the HFD were distributed in separate areas in the FBG-GTT2h diagram. The respective areas could be defined as the normal state, prediabetes state, and diabetes state, respectively. Based on the results, the criteria for prediabetes could be defined for the Gk+/− strain developed in this study. PMID:25765873

  16. Glucokinase gene promoter -30G>A polymorphism: a cross-sectional association study with obesity, diabetes Mellitus, hyperlipidemia, hypertension and metabolic syndrome in an Iranian hospital

    Directory of Open Access Journals (Sweden)

    Mohammad Reza Oladi

    2012-08-01

    Full Text Available OBJECTIVE: A -30G>A single nucleotide polymorphism in the promoter region of the glucokinase gene has been previously associated with obesity, insulin resistance and diabetes. The present study aimed to evaluate the association of this polymorphism with obesity and its comorbidities in a population from Northeast Iran. METHODS: Five hundred and forty-two subjects aged 18 to 65 years were included in the study and divided into normal (BMI30, n=187 groups. All subjects were genotyped for the -30G>A polymorphism using the polymerase chain reaction-restriction fragment length polymorphism technique. RESULTS: The genotypes and allele frequencies of the three groups did not differ significantly (p>0.05. When the study population was categorized according to diabetes mellitus, hyperlipidemia, hypertension and metabolic syndrome status, no significant difference in -30G>A genotypes and alleles was found between the subgroups with and without these disorders (p>0.05, apart from a significantly higher frequency of the G allele in the hyperlipidemic vs. non-hyperlipidemic subgroup (pA polymorphism and high body mass index in the Iranian population.

  17. Zinc finger nuclease mediated knockout of ADP-dependent glucokinase in cancer cell lines: effects on cell survival and mitochondrial oxidative metabolism.

    Directory of Open Access Journals (Sweden)

    Susan Richter

    Full Text Available Zinc finger nucleases (ZFN are powerful tools for editing genes in cells. Here we use ZFNs to interrogate the biological function of ADPGK, which encodes an ADP-dependent glucokinase (ADPGK, in human tumour cell lines. The hypothesis we tested is that ADPGK utilises ADP to phosphorylate glucose under conditions where ATP becomes limiting, such as hypoxia. We characterised two ZFN knockout clones in each of two lines (H460 and HCT116. All four clones had frameshift mutations in all alleles at the target site in exon 1 of ADPGK, and were ADPGK-null by immunoblotting. ADPGK knockout had little or no effect on cell proliferation, but compromised the ability of H460 cells to survive siRNA silencing of hexokinase-2 under oxic conditions, with clonogenic survival falling from 21±3% for the parental line to 6.4±0.8% (p = 0.002 and 4.3±0.8% (p = 0.001 for the two knockouts. A similar increased sensitivity to clonogenic cell killing was observed under anoxia. No such changes were found when ADPGK was knocked out in HCT116 cells, for which the parental line was less sensitive than H460 to anoxia and to hexokinase-2 silencing. While knockout of ADPGK in HCT116 cells caused few changes in global gene expression, knockout of ADPGK in H460 cells caused notable up-regulation of mRNAs encoding cell adhesion proteins. Surprisingly, we could discern no consistent effect on glycolysis as measured by glucose consumption or lactate formation under anoxia, or extracellular acidification rate (Seahorse XF analyser under oxic conditions in a variety of media. However, oxygen consumption rates were generally lower in the ADPGK knockouts, in some cases markedly so. Collectively, the results demonstrate that ADPGK can contribute to tumour cell survival under conditions of high glycolytic dependence, but the phenotype resulting from knockout of ADPGK is cell line dependent and appears to be unrelated to priming of glycolysis in these lines.

  18. Zinc finger nuclease mediated knockout of ADP-dependent glucokinase in cancer cell lines: effects on cell survival and mitochondrial oxidative metabolism.

    Science.gov (United States)

    Richter, Susan; Morrison, Shona; Connor, Tim; Su, Jiechuang; Print, Cristin G; Ronimus, Ron S; McGee, Sean L; Wilson, William R

    2013-01-01

    Zinc finger nucleases (ZFN) are powerful tools for editing genes in cells. Here we use ZFNs to interrogate the biological function of ADPGK, which encodes an ADP-dependent glucokinase (ADPGK), in human tumour cell lines. The hypothesis we tested is that ADPGK utilises ADP to phosphorylate glucose under conditions where ATP becomes limiting, such as hypoxia. We characterised two ZFN knockout clones in each of two lines (H460 and HCT116). All four clones had frameshift mutations in all alleles at the target site in exon 1 of ADPGK, and were ADPGK-null by immunoblotting. ADPGK knockout had little or no effect on cell proliferation, but compromised the ability of H460 cells to survive siRNA silencing of hexokinase-2 under oxic conditions, with clonogenic survival falling from 21±3% for the parental line to 6.4±0.8% (p = 0.002) and 4.3±0.8% (p = 0.001) for the two knockouts. A similar increased sensitivity to clonogenic cell killing was observed under anoxia. No such changes were found when ADPGK was knocked out in HCT116 cells, for which the parental line was less sensitive than H460 to anoxia and to hexokinase-2 silencing. While knockout of ADPGK in HCT116 cells caused few changes in global gene expression, knockout of ADPGK in H460 cells caused notable up-regulation of mRNAs encoding cell adhesion proteins. Surprisingly, we could discern no consistent effect on glycolysis as measured by glucose consumption or lactate formation under anoxia, or extracellular acidification rate (Seahorse XF analyser) under oxic conditions in a variety of media. However, oxygen consumption rates were generally lower in the ADPGK knockouts, in some cases markedly so. Collectively, the results demonstrate that ADPGK can contribute to tumour cell survival under conditions of high glycolytic dependence, but the phenotype resulting from knockout of ADPGK is cell line dependent and appears to be unrelated to priming of glycolysis in these lines.

  19. Arterial oxygen partial pressures reduce the insulin-dependent induction of the perivenously located glucokinase in rat hepatocyte cultures: mimicry of arterial oxygen pressures by H2O2.

    OpenAIRE

    Kietzmann, T; Roth, U; Freimann, S; Jungermann, K

    1997-01-01

    Liver glucokinase (GK) is localized predominantly in the perivenous zone. GK mRNA was induced by insulin maximally under venous O2 partial pressure (pO2) and only half-maximally under arterial pO2. CoCl2 and desferrioxamine mimicked venous pO2 and enhanced the insulin-dependent induction of GK mRNA under arterial pO2. H2O2 mimicked arterial pO2 and reduced insulin-induced GK mRNA under venous pO2 to the lower arterial levels. Thus the zonal O2 gradient in liver seems to have a key role in the...

  20. The association between Mediterranean Diet Score and glucokinase regulatory protein gene variation on the markers of cardiometabolic risk: an analysis in the European Prospective Investigation into Cancer (EPIC)-Norfolk study.

    Science.gov (United States)

    Sotos-Prieto, Mercedes; Luben, Robert; Khaw, Kay-Tee; Wareham, Nicholas J; Forouhi, Nita G

    2014-07-14

    Consumption of a Mediterranean diet (MD) and genetic variation in the glucokinase regulatory protein (GCKR) gene have been reported to be associated with TAG and glucose metabolism. It is uncertain whether there is any interaction between these factors. Therefore, the aims of the present study were to test the association of adherence to a MD and rs780094 (G>A) SNP in the GCKR gene with the markers of cardiometabolic risk, and to investigate the interaction between genetic variation and MD adherence. We studied 20 986 individuals from the European Prospective Investigation into Cancer (EPIC)-Norfolk study. The relative Mediterranean Diet Score (rMED: range 0-18) was used to assess MD adherence. Linear regression was used to estimate the association between the rMED, genotype and cardiometabolic continuous traits, adjusting for potential confounders. In adjusted analyses, we observed independent associations of MD adherence and genotype with cardiometabolic risk, with the highest risk group (AA genotype; lowest rMED) having higher concentrations of TAG, total cholesterol and apoB (12·5, 2·3 and 3·1%, respectively) v. those at the lowest risk (GG genotype; highest rMED). However, the associations of MD adherence with metabolic markers did not differ by genotype, with no significant gene-diet interactions for lipids or for glycated Hb. In conclusion, we found independent associations of the rMED and of the GCKR genotype with cardiometabolic profile, but found no evidence of interaction between them.

  1. Novel glucokinase gene mutation in the first Macedonian family tested for MODY.

    Science.gov (United States)

    Kocova, M; Elblova, L; Pruhova, S; Lebl, J; Dusatkova, P

    2017-08-01

    We present a boy with mild hyperglycemia detected during an upper respiratory infection. Novel splicing mutation in the intron 1 of the GCK gene (c.45+1G>A) was detected, and was subsequently confirmed in his father. This is the first case of genetically confirmed Macedonian family with MODY. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. cDNA sequence and tissue expression analysis of glucokinase from ...

    African Journals Online (AJOL)

    Yomi

    2012-01-10

    Jan 10, 2012 ... distribution of GK mRNA in brain, mesenteric adipose tissue, spleen, white muscle and liver of grass ... expression profile of GK mRNA in liver normalized with β-actin level was 31, 454 and 649-fold compared .... Primers and expected products used for GK gene cDNA RT-PCR, RACE and real-time PCR.

  3. Glucokinase links Kruppel-like factor 6 to the regulation of hepatic insulin sensitivity in nonalcoholic fatty liver disease

    NARCIS (Netherlands)

    Bechmann, Lars P.; Gastaldelli, Amalia; Vetter, Diana; Patman, Gillian L.; Pascoe, Laura; Hannivoort, Rebekka A.; Lee, Ursula E.; Fiel, Isabel; Munoz, Ursula; Ciociaro, Demetrio; Lee, Young-Min; Buzzigoli, Emma; Miele, Luca; Hui, Kei Y.; Bugianesi, Elisabetta; Burt, Alastair D.; Day, Christopher P.; Mari, Andrea; Agius, Loranne; Walker, Mark; Friedman, Scott L.; Reeves, Helen L.

    The polymorphism, KLF6-IVS1-27A, in the Kruppel-like factor 6 (KLF6) transcription factor gene enhances its splicing into antagonistic isoforms and is associated with delayed histological progression of nonalcoholic fatty liver disease (NAFLD). To explore a potential role for KLF6 in the development

  4. Achieving High Yield of Lactic Acid for Antimicrobial Characterization in Cephalosporin-Resistant Lactobacillus by the Co-Expression of the Phosphofructokinase and Glucokinase.

    Science.gov (United States)

    Gong, Yahui; Li, Tiyuan; Li, Shiyu; Jiang, Zhenyou; Yang, Yan; Huang, Junli; Liu, Zhaobing; Sun, Hanxiao

    2016-06-28

    Lactobacilli are universally recognized as probiotics that are widely used in the adjuvant treatment of inflammatory diseases, such as vaginitis and enteritis. With the overuse of antibiotics in recent years, the lactobacilli in the human body are killed, which could disrupt the microecological balance in the human body and affect health adversely. In this work, cephalosporin-resistant Lactobacillus casei RL20 was obtained successfully from the feces of healthy volunteers, which possessed a stable genetic set. However, the shortage of lactic acid (72.0 g/l at 48 h) by fermentation did not meet the requirement for its use in medicine. To increase the production of lactic acid, the functional genes pfk and glk were introduced into the wild strain. A yield of 144.2 g/l lactic acid was obtained in the transgenic L. casei RL20-2 after fermentation for 48 h in 1 L of basic fermentation medium with an initial glucose concentration of 100 g/l and increasing antibacterial activity. These data suggested that L. casei RL20-2 that exhibited a high yield of lactic acid may be a potential probiotic to inhibit the spread of bacterial infectious diseases and may be used for vaginitis therapy.

  5. A -30G>A polymorphism of the beta-cell-specific glucokinase promoter associates with hyperglycemia in the general population of whites

    DEFF Research Database (Denmark)

    Rose, Christian S; Ek, Jakob; Urhammer, Søren A

    2005-01-01

    of whites, as well as with features of the World Health Organization (WHO)-defined metabolic syndrome. The GCK -30G>A polymorphism was genotyped in the population-based Inter99 study cohort (5,965 subjects) and in 332 nondiabetic subjects and 1,063 patients with type 2 diabetes. In the Inter99 cohort......A graded relationship has been reported between fasting and postprandial plasma glucose levels and the subsequent risk of cardiovascular morbidity and mortality. We hypothesized that the GCK -30G>A promoter polymorphism is associated with elevated glycemia in the middle-aged general population......, the GCK -30A allele was associated with increased fasting (P 1,325 subjects with the metabolic syndrome than among 1,679 subjects without any components...

  6. Bisphenol A impairs hepatic glucose sensing in C57BL/6 male mice.

    Directory of Open Access Journals (Sweden)

    Leigh Perreault

    Full Text Available AIMS/HYPOTHESIS: Glucose sensing (eg. glucokinase activity becomes impaired in the development of type 2 diabetes, the etiology of which is unclear. Estrogen can stimulate glucokinase activity, whereas the pervasive environmental pollutant bisphenol A (BPA can inhibit estrogen action, hence we aimed to determine the effect of BPA on glucokinase activity directly. METHODS: To evaluate a potential acute effect on hepatic glucokinase activity, BPA in water (n = 5 vs. water alone (n = 5 was administered at the EPA's purported "safe dose" (50 µg/kg by gavage to lean 6-month old male C57BL/6 mice. Two hours later, animals were euthanized and hepatic glucokinase activity measured over glucose levels from 1-20 mmol/l in liver homogenate. To determine the effect of chronic BPA exposure on hepatic glucokinase activity, lean 6-month old male C57BL/6 mice were provided with water (n = 15 or water with 1.75 mM BPA (∼50 µg/kg/day; n = 14 for 2 weeks. Following the 2-week exposure, animals were euthanized and glucokinase activity measured as above. RESULTS: Hepatic glucokinase activity was signficantly suppressed after 2 hours in animals given an oral BPA bolus compared to those who received only water (p = 0.002-0.029 at glucose 5-20 mmol/l; overall treatment effect p<0.001. Exposure to BPA over 2 weeks also suppressed hepatic glucokinase activity in exposed vs. unexposed mice (overall treatment effect, p = 0.003. In both experiments, the Hill coefficient was higher and Vmax lower in mice treated with BPA. CONCLUSIONS/INTERPRETATION: Both acute and chronic exposure to BPA significantly impair hepatic glucokinase activity and function. These findings identify a potential mechanism for how BPA may increase risk for diabetes.

  7. Genetics Home Reference: permanent neonatal diabetes mellitus

    Science.gov (United States)

    ... AL. Update on mutations in glucokinase (GCK), which cause maturity-onset diabetes of the young, permanent neonatal diabetes, and hyperinsulinemic hypoglycemia. Hum Mutat. 2009 Nov;30(11):1512-26. ...

  8. Characterization of two MODY2 mutations with different susceptibility to activation

    Energy Technology Data Exchange (ETDEWEB)

    Langer, Sara; Platz, Christian; Waterstradt, Rica; Baltrusch, Simone, E-mail: simone.baltrusch@med.uni-rostock.de

    2015-09-04

    Glucokinase plays a key role in glucose sensing in pancreatic beta cells and in liver metabolism. Heterozygous inactivating glucokinase mutations cause the autosomal dominantly inherited MODY2 subtype of maturity-onset diabetes of the young. The goal of this study was to elucidate the pathogenicity of the recently described glucokinase mutants L304P and L315H, located in an alpha-helix and connecting region, respectively, at the outer region of the large domain of glucokinase. Both mutants showed wild-type-like cytosolic localization, but faster protein degradation in insulin-secreting MIN6 cells. However, strongly reduced nuclear/cytoplasmic localization of the mutants was observed in primary hepatocytes suggesting reduced interaction with the liver specific glucokinase regulatory protein. Both mutants displayed a significantly lowered glucokinase activity compared to the wild-type protein. Even though the L315H protein showed the lowest enzymatic activity, this mutant was very sensitive to allosteric activation. The endogenous activator fructose-2,6-bisphosphatase evoked an increase in glucokinase activity for both mutants, but much stronger for L315H compared to L304P. The synthetic activator RO281675 was ineffective against the L304P mutant. Expression of the mutant proteins evoked loss of glucose-induced insulin secretion in MIN6 cells. Administration of RO281675 increased insulin secretion, however, only for the L315H mutant. Thus, a glucokinase activator drug therapy may help MODY2 patients not in general, but seems to be a useful strategy for carriers of the L315H glucokinase mutation. - Highlights: • The GK mutants L304P and L315H display a highly reduced enzymatic activity. • In hepatocytes both mutations lower the nuclear/cytoplasmic localization ratio of GK. • Both mutants inhibit stimulus-secretion coupling in insulin-producing cells. • Activation by fructose-2,6-bisphosphatase and by RO281675 is stronger for L315H. • RO281675 stimulates

  9. Supraoptic oxytocin and vasopressin neurons function as glucose and metabolic sensors.

    Science.gov (United States)

    Song, Zhilin; Levin, Barry E; Stevens, Wanida; Sladek, Celia D

    2014-04-01

    Neurons in the supraoptic nuclei (SON) produce oxytocin and vasopressin and express insulin receptors (InsR) and glucokinase. Since oxytocin is an anorexigenic agent and glucokinase and InsR are hallmarks of cells that function as glucose and/or metabolic sensors, we evaluated the effect of glucose, insulin, and their downstream effector ATP-sensitive potassium (KATP) channels on calcium signaling in SON neurons and on oxytocin and vasopressin release from explants of the rat hypothalamo-neurohypophyseal system. We also evaluated the effect of blocking glucokinase and phosphatidylinositol 3 kinase (PI3K; mediates insulin-induced mobilization of glucose transporter, GLUT4) on responses to glucose and insulin. Glucose and insulin increased intracellular calcium ([Ca(2+)]i). The responses were glucokinase and PI3K dependent, respectively. Insulin and glucose alone increased vasopressin release (P glucose in the presence of insulin. The oxytocin (OT) and vasopressin (VP) responses to insulin+glucose were blocked by the glucokinase inhibitor alloxan (4 mM; P ≤ 0.002) and the PI3K inhibitor wortmannin (50 nM; OT: P = 0.03; VP: P ≤ 0.002). Inactivating K ATP channels with 200 nM glibenclamide increased oxytocin and vasopressin release (OT: P neurons functioning as glucose and "metabolic" sensors to participate in appetite regulation.

  10. Supraoptic oxytocin and vasopressin neurons function as glucose and metabolic sensors

    Science.gov (United States)

    Song, Zhilin; Levin, Barry E.; Stevens, Wanida

    2014-01-01

    Neurons in the supraoptic nuclei (SON) produce oxytocin and vasopressin and express insulin receptors (InsR) and glucokinase. Since oxytocin is an anorexigenic agent and glucokinase and InsR are hallmarks of cells that function as glucose and/or metabolic sensors, we evaluated the effect of glucose, insulin, and their downstream effector ATP-sensitive potassium (KATP) channels on calcium signaling in SON neurons and on oxytocin and vasopressin release from explants of the rat hypothalamo-neurohypophyseal system. We also evaluated the effect of blocking glucokinase and phosphatidylinositol 3 kinase (PI3K; mediates insulin-induced mobilization of glucose transporter, GLUT4) on responses to glucose and insulin. Glucose and insulin increased intracellular calcium ([Ca2+]i). The responses were glucokinase and PI3K dependent, respectively. Insulin and glucose alone increased vasopressin release (P glucose in the presence of insulin. The oxytocin (OT) and vasopressin (VP) responses to insulin+glucose were blocked by the glucokinase inhibitor alloxan (4 mM; P ≤ 0.002) and the PI3K inhibitor wortmannin (50 nM; OT: P = 0.03; VP: P ≤ 0.002). Inactivating KATP channels with 200 nM glibenclamide increased oxytocin and vasopressin release (OT: P neurons functioning as glucose and “metabolic” sensors to participate in appetite regulation. PMID:24477542

  11. Transcriptional profiling of extracellular amino acid sensing in Saccharomyces cerevisiae and the role of Stp1p and Stp2p

    DEFF Research Database (Denmark)

    Eckert-Boulet, Nadine; Nielsen, P.S.; Friis, Carsten

    2004-01-01

    Tdh1p and glucokinase (Glk1p), shows increased transcription levels in either or both of the mutants. Also, most of the structural genes involved in trehalose and glycogen synthesis and a few genes in the glyoxylate cycle and the pentose phosphate pathway are derepressed in the ssy1 and stp1 stp2...

  12. Genetic basis of interindividual susceptibility to cancer cachexia ...

    Indian Academy of Sciences (India)

    response to therapy, quality of life and duration of survival. Cancer cachexia ..... protein (GCKR) binds and moves glucokinase (GK); thereby, controlling .... substrate metabolism through impairment of insulin action and insulin ..... men, but not in men. (van. R aalte et al. Jewell and. 2012. ). C idlow ski. 2007. A ssociated w ith.

  13. Fulltext PDF

    Indian Academy of Sciences (India)

    2014-01-27

    Jan 27, 2014 ... essential role of evolution in selecting the molecules of life. .... 'right' molecules, and brings down the error rate to an acceptable level. .... It is worth remembering that the inability to grow .... glucokinase from Saccharomyces cerevisiae seen along the two .... Each chain is a polymer of 11–15 glucose units. 4.

  14. Characterisation of the Aspergillus nidulans frA1 mutant: hexose phosphorylation and apparent lack of involvement of hexokinase in glucose repression.

    NARCIS (Netherlands)

    Ruijter, G.J.G.; Panneman, H.; Broeck, van den H.C.; Bennett, J.M.; Visser, J.

    1996-01-01

    Hexose phosphorylation was studied in Aspergillus nidulans wild-type and in a fructose non-utilising mutant (frA). The data indicate the presence of at least one hexokinase and one glucokinase in wild-type A. nidulans, while the frA1 mutant lacks hexokinase activity. The A. nidulans gene encoding

  15. Glucose 6-phosphate compartmentation and the control of glycogen synthesis

    NARCIS (Netherlands)

    Meijer, Alfred

    2002-01-01

    Using adenovirus-mediated gene transfer into FTO-2B cells, a rat hepatoma cell line, we have overexpressed hexokinase I, (HK I), glucokinase (GK), liver glycogen synthase (LGS), muscle glycogen synthase (MGS), and combinations of each of the two glucose phosphorylating enzymes with each one of the

  16. UCP2 mRNA expression is dependent on glucose metabolism in pancreatic islets

    International Nuclear Information System (INIS)

    Dalgaard, Louise T.

    2012-01-01

    Highlights: ► UCP2 mRNA levels are decreased in islets of Langerhans from glucokinase deficient mice. ► UCP2 mRNA up-regulation by glucose is dependent on glucokinase. ► Absence of UCP2 increases GSIS of glucokinase heterozygous pancreatic islets. ► This may protect glucokinase deficient mice from hyperglycemic damages. -- Abstract: Uncoupling Protein 2 (UCP2) is expressed in the pancreatic β-cell, where it partially uncouples the mitochondrial proton gradient, decreasing both ATP-production and glucose-stimulated insulin secretion (GSIS). Increased glucose levels up-regulate UCP2 mRNA and protein levels, but the mechanism for UCP2 up-regulation in response to increased glucose is unknown. The aim was to examine the effects of glucokinase (GK) deficiency on UCP2 mRNA levels and to characterize the interaction between UCP2 and GK with regard to glucose-stimulated insulin secretion in pancreatic islets. UCP2 mRNA expression was reduced in GK+/− islets and GK heterozygosity prevented glucose-induced up-regulation of islet UCP2 mRNA. In contrast to UCP2 protein function UCP2 mRNA regulation was not dependent on superoxide generation, but rather on products of glucose metabolism, because MnTBAP, a superoxide dismutase mimetic, did not prevent the glucose-induced up-regulation of UCP2. Glucose-stimulated insulin secretion was increased in UCP2−/− and GK+/− islets compared with GK+/− islets and UCP2 deficiency improved glucose tolerance of GK+/− mice. Accordingly, UCP2 deficiency increased ATP-levels of GK+/− mice. Thus, the compensatory down-regulation of UCP2 is involved in preserving the insulin secretory capacity of GK mutant mice and might also be implicated in limiting disease progression in MODY2 patients.

  17. Maturity-onset diabetes of the young--MODY. Molekylaergenetiske, patofysiologiske og kliniske karakteristika

    DEFF Research Database (Denmark)

    Hansen, Torben; Urhammer, Søren A; Pedersen, Oluf Borbye

    2002-01-01

    Maturity-onset diabetes of the young (MODY) is a genetically and clinically heterogeneous subtype of type 2 diabetes characterised by an early onset, an autosomal dominant inheritance, and a primary defect in insulin secretion. MODY comprises 2-5% of cases of type 2 diabetes. So far, six MODY genes...... have been identified (MODY1-6): hepatocyte nuclear factor (HNF-4 alpha), glucokinase, HNF-1 alpha, HNF-1 beta, insulin promoter factor 1(IPF-1), and neurogenic differentiation factor 1 (NEUROD1). MODY2 and MODY3 are the most common forms of MODY. Mutations in glucokinase/MODY2 result in a mild form...... of diabetes. In contrast, MODY3 and some of the other MODY forms are characterised by major insulin secretory defects and severe hyperglycaemia associated with microvascular complications. About 25% of known MODY is caused by mutations in yet unknown genes and present results suggest that other monogenic...

  18. Dual role of proapoptotic BAD in insulin secretion and beta cell survival

    OpenAIRE

    Danial, Nika N.; Walensky, Loren D.; Zhang, Chen-Yu; Choi, Cheol Soo; Fisher, Jill K.; Molina, Anthony J. A.; Datta, Sandeep Robert; Pitter, Kenneth L.; Bird, Gregory H.; Wikstrom, Jakob D.; Deeney, Jude T.; Robertson, Kirsten; Morash, Joel; Kulkarni, Ameya; Neschen, Susanne

    2008-01-01

    The proapoptotic BCL-2 family member BAD resides in a glucokinase-containing complex that regulates glucose-driven mitochondrial respiration. Here, we present genetic evidence of a physiologic role for BAD in glucose-stimulated insulin secretion by beta cells. This novel function of BAD is specifically dependent upon the phosphorylation of its BH3 sequence, previously defined as an essential death domain. We highlight the pharmacologic relevance of phosphorylated BAD BH3 by using cell-permeab...

  19. Novel N-(pyrimidin-4-ylthiazol-2-amine derivatives as dual-action hypoglycemic agents that activate GK and PPARγ

    Directory of Open Access Journals (Sweden)

    Hui-peng Song

    2011-10-01

    Full Text Available A series of novel N-(pyrimidin-4-ylthiazol-2-amine derivatives have been synthesized and evaluated as glucokinase (GK activators. Ethyl 2-(6-(4-(2-hydroxyethylpiperazin-1-yl-2-methylpyrimidin-4-yl-aminothiazole-5-carboxylate was found to be a potent dual-acting hypoglycemic agent activating both GK and PPARγ. When given orally to normal mice, the compound demonstrated significant efficacy in decreasing the glucose level after oral glucose loading.

  20. GKAs for diabetes therapy: why no clinically useful drug after two decades of trying?

    Science.gov (United States)

    Matschinsky, Franz M

    2013-02-01

    Results of basic biochemical and physiological research, strongly endorsed by findings in human pathophysiology and genetics, had characterized the glucose phosphorylating enzyme glucokinase as a critical player in normal glucose homeostasis, diabetes mellitus, and hyperinsulinemic hypoglycemia, and identified the enzyme as a promising new drug target. R&D initiated in the early 1990s and directed at this target discovered glucokinase activators (GKAs) as a new class of potentially antidiabetic drugs. GKAs were characterized as nonessential allosteric activators that increase glucose affinity and V(max) of the enzyme, thus stimulating glucose metabolism in glucokinase expressing tissue, of foremost functional significance in the insulin producing pancreatic beta cells and the liver. The results of preclinical testing of GKAs by many pharmaceutical companies demonstrated uniformly high hypoglycemic efficacy in normal and diabetic animals. GKAs were also highly effective in Phase I trials in patients with type 2 diabetes mellitus (T2DM). However, results of a recent Phase II trial were less encouraging because patients developed hyperlipidemia and vascular hypertension, and the drug lost efficacy within several months. This outcome is prompting a reappraisal of the GKA strategy. In this opinion article, the 'pros and cons' of the strategy to use these compounds in diabetes management are critically reexamined and suggestions are made that might facilitate progress of GKA R&D that could still result in a novel antidiabetic medicine. Copyright © 2013 Elsevier Ltd. All rights reserved.

  1. Liver carbohydrates metabolism: A new islet-neogenesis associated protein peptide (INGAP-PP) target.

    Science.gov (United States)

    Villagarcía, Hernán Gonzalo; Román, Carolina Lisi; Castro, María Cecilia; González, Luisa Arbeláez; Ronco, María Teresa; Francés, Daniel Eleazar; Massa, María Laura; Maiztegui, Bárbara; Flores, Luis Emilio; Gagliardino, Juan José; Francini, Flavio

    2018-03-01

    Islet-Neogenesis Associated Protein-Pentadecapeptide (INGAP-PP) increases β-cell mass and enhances glucose and amino acids-induced insulin secretion. Our aim was to demonstrate its effect on liver metabolism. For that purpose, adult male Wistar rats were injected twice-daily (10 days) with saline solution or INGAP-PP (250 μg). Thereafter, serum glucose, triglyceride and insulin levels were measured and homeostasis model assessment (HOMA-IR) and hepatic insulin sensitivity (HIS) were determined. Liver glucokinase and glucose-6-phosphatase (G-6-Pase) expression and activity, phosphoenolpyruvate carboxykinase (PEPCK) expression, phosphofructokinase-2 (PFK-2) protein content, P-Akt/Akt and glycogen synthase kinase-3β (P-GSK3/GSK3) protein ratios and glycogen deposit were also determined. Additionally, glucokinase activity and G-6-Pase and PEPCK gene expression were also determined in isolated hepatocytes from normal rats incubated with INGAP-PP (5 μg/ml). INGAP-PP administration did not modify any of the serum parameters tested but significantly increased activity of liver glucokinase and the protein level of its cytosolic activator, PFK-2. Conversely, INGAP-PP treated rats decreased gene expression and enzyme activity of gluconeogenic enzymes, G-6-Pase and PEPCK. They also showed a higher glycogen deposit and P-GSK3/GSK3 and P-Akt/Akt ratio. In isolated hepatocytes, INGAP-PP increased GK activity and decreased G-6-Pase and PEPCK expression. These results demonstrate a direct effect of INGAP-PP on the liver acting through P-Akt signaling pathway. INGAP-PP enhances liver glucose metabolism and deposit and reduces its production/output, thereby contributing to maintain normal glucose homeostasis. These results reinforce the concept that INGAP-PP might become a useful tool to treat people with impaired islet/liver glucose metabolism as it occurs in T2D. Copyright © 2018 Elsevier Inc. All rights reserved.

  2. [Maturity onset diabetes of the young (MODY) - screening, diagnostic and therapy].

    Science.gov (United States)

    Kaser, Susanne; Resl, Michael

    2016-04-01

    Maturity onset diabetes of the young (MODY) is a group of monogenetic diabetes types affecting up to 2% all known diabetics. Transcription factor MODY (HNF1α, HNF4α), the most frequent forms of MODY, allow treatment with sulfonylureas, mutations of glucokinase (GCK-MODY) usually do not require any therapy. Especially in younger patients correct diagnosis of MODY often results in discontinuation of insulin therapy and initiation of a sulfonylurea. Accordingly, in patients with diabetes onset below age of 25 years, with a positive family history for diabetes and negative autoantibodies screening for MODY is recommended.

  3. [The trend of new drug development for the treatment of diabetes mellitus].

    Science.gov (United States)

    Kaku, Kohei

    2015-12-01

    The trend of new drug development in the field of diabetes mellitus is overviewed. The hypoglycemic drugs such as glucagon receptor antagonists, glucokinase activators, and GPR agonists and oral medication of GLP-1 receptor agonist are under phase 2 trial in Japan. As for therapeutic medicines for diabetic nephropathy, atrasentan as an endothelin A receptor antagonist is in phase 3 trial, and bardoxolone methyl as Nrf2 activator in phase 2 in Japan. Canagliflozin, a SGLT2 inhibitor, is in phase 3 study to obtain new indication of diabetic nephropathy. An environment surrounding development of therapeutic medicines for diabetes has been tough since FDA guidance in 2008.

  4. New ways to test beta cell functionality in health and diabetes

    DEFF Research Database (Denmark)

    Korsgaard, Thomas Vagn

    the final insulin secretion pattern. We show that the first phase of insulin secretion is related to the rate of change of glucose in a non-linear saturable fashion, and that the second phase is due to translocation of glucokinase from an inactive to an active state. Hence, the glucose sensing mechanisms...... plasma glucose has returned to fasting values, hence secretion of insulin continues despite glucose has returned to fasting values, and the increased insulin does not lead to hypoglycaemia. Hence in healthy subjects it appears that the glucose uptake is controlled in such a way as to follow the rate...

  5. [Diabetes in Pregnancy - Type 1/Type 2 Diabetes Mellitus and Gestational Diabetes Mellitus].

    Science.gov (United States)

    Kleinwechter, Helmut; Demandt, Norbert

    2016-09-01

    In Germany in 5.5% of all births diabetes is registered. In patients with type 1 and type 2 diabetes planning pregnancy, preconception counseling, diabetologic care with optimized periconceptional metabolic control and folic acid supplementation are essential for good pregnancy outcome. Gestational diabetes (GDM) should be diagnosed timely and managed according to existing guidelines. GDM is treated with insulin in approximately 20%. In 1-2% of GDM cases a glucokinase gene mutation is present (MODY 2). Pregnancies after bariatric-metabolic surgery are increasing and show high risks. © Georg Thieme Verlag KG Stuttgart · New York.

  6. Dual role of proapoptotic BAD in insulin secretion and beta cell survival.

    Science.gov (United States)

    Danial, Nika N; Walensky, Loren D; Zhang, Chen-Yu; Choi, Cheol Soo; Fisher, Jill K; Molina, Anthony J A; Datta, Sandeep Robert; Pitter, Kenneth L; Bird, Gregory H; Wikstrom, Jakob D; Deeney, Jude T; Robertson, Kirsten; Morash, Joel; Kulkarni, Ameya; Neschen, Susanne; Kim, Sheene; Greenberg, Michael E; Corkey, Barbara E; Shirihai, Orian S; Shulman, Gerald I; Lowell, Bradford B; Korsmeyer, Stanley J

    2008-02-01

    The proapoptotic BCL-2 family member BAD resides in a glucokinase-containing complex that regulates glucose-driven mitochondrial respiration. Here, we present genetic evidence of a physiologic role for BAD in glucose-stimulated insulin secretion by beta cells. This novel function of BAD is specifically dependent upon the phosphorylation of its BH3 sequence, previously defined as an essential death domain. We highlight the pharmacologic relevance of phosphorylated BAD BH3 by using cell-permeable, hydrocarbon-stapled BAD BH3 helices that target glucokinase, restore glucose-driven mitochondrial respiration and correct the insulin secretory response in Bad-deficient islets. Our studies uncover an alternative target and function for the BAD BH3 domain and emphasize the therapeutic potential of phosphorylated BAD BH3 mimetics in selectively restoring beta cell function. Furthermore, we show that BAD regulates the physiologic adaptation of beta cell mass during high-fat feeding. Our findings provide genetic proof of the bifunctional activities of BAD in both beta cell survival and insulin secretion.

  7. Palmitoleic Acid Improves Metabolic Functions in Fatty Liver by PPARα-Dependent AMPK Activation.

    Science.gov (United States)

    de Souza, Camila O; Teixeira, Alexandre A S; Biondo, Luana A; Lima Junior, Edson A; Batatinha, Helena A P; Rosa Neto, Jose C

    2017-08-01

    Palmitoleic acid, since described as lipokine, increases glucose uptake by modulation of 5'AMP-activated protein kinase (AMPK), as well as increasing lipolysis by activation of peroxisome proliferator-activated receptor-α (PPARα), in adipose tissue. However, in liver, the effects of palmitoleic acid on glucose metabolism and the role of PPARα remain unknown. To investigate whether palmitoleic acid improved the hepatic insulin sensitivity of obese mice. C57BL6 and PPARα knockout (KO) mice were fed for 12 weeks with a standard diet (SD) or high-fat diet (HF), and in the last 2 weeks were treated with oleic or palmitoleic acid. Palmitoleic acid promoted a faster uptake of glucose in the body, associated with higher insulin concentration; however, even when stimulated with insulin, palmitoleic acid did not modulate the insulin pathway (AKT, IRS). Palmitoleic acid increased the phosphorylation of AMPK, upregulated glucokinase and downregulated SREBP-1. Regarding AMPK downstream, palmitoleic acid increased the production of FGF-21 and stimulated the expression of PPARα. Palmitoleic acid treatment did not increase AMPK phosphorylation, modulate glucokinase or increase FGF-21 in liver of PPARα KO mice. In mice fed with a high-fat diet, palmitoleic acid supplementation stimulated the uptake of glucose in liver through activation of AMPK and FGF-21, dependent on PPARα. J. Cell. Physiol. 232: 2168-2177, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  8. GCK-MODY diabetes as a protein misfolding disease: the mutation R275C promotes protein misfolding, self-association and cellular degradation.

    Science.gov (United States)

    Negahdar, Maria; Aukrust, Ingvild; Molnes, Janne; Solheim, Marie H; Johansson, Bente B; Sagen, Jørn V; Dahl-Jørgensen, Knut; Kulkarni, Rohit N; Søvik, Oddmund; Flatmark, Torgeir; Njølstad, Pål R; Bjørkhaug, Lise

    2014-01-25

    GCK-MODY, dominantly inherited mild hyperglycemia, is associated with more than 600 mutations in the glucokinase gene. Different molecular mechanisms have been shown to explain GCK-MODY. Here, we report a Pakistani family harboring the glucokinase mutation c.823C>T (p.R275C). The recombinant and in cellulo expressed mutant pancreatic enzyme revealed slightly increased enzyme activity (kcat) and normal affinity for α-D-glucose, and resistance to limited proteolysis by trypsin comparable with wild-type. When stably expressed in HEK293 cells and MIN6 β-cells (at different levels), the mutant protein appeared misfolded and unstable with a propensity to form dimers and aggregates. Its degradation rate was increased, involving the lysosomal and proteasomal quality control systems. On mutation, a hydrogen bond between the R275 side-chain and the carbonyl oxygen of D267 is broken, destabilizing the F260-L271 loop structure and the protein. This promotes the formation of dimers/aggregates and suggests that an increased cellular degradation is the molecular mechanism by which R275C causes GCK-MODY. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  9. Changes in expression of hepatic genes involved in energy metabolism during hibernation in captive, adult, female Japanese black bears (Ursus thibetanus japonicus).

    Science.gov (United States)

    Shimozuru, Michito; Kamine, Akari; Tsubota, Toshio

    2012-10-01

    Hibernating bears survive up to 6 months without feeding by utilizing stored body fat as fuel. To investigate how bears maintain energy homeostasis during hibernation, we analyzed changes in mRNA expression of hepatic genes involved in energy metabolism throughout the hibernation period in captive, adult, female Japanese black bears (Ursus thibetanus japonicus). Real-time PCR analysis revealed down-regulation of glycolysis- (e.g., glucokinase), amino acid catabolism- (e.g., alanine aminotransferase) and de novo lipogenesis-related genes (e.g., acetyl-CoA carboxylase 1), and up-regulation of gluconeogensis- (e.g., pyruvate carboxylase), β-oxidation- (i.e., uncoupling protein 2) and ketogenesis-related genes (i.e., 3-hydroxy-3-methylglutary-CoA synthase 2), during hibernation, compared to the active period (June). In addition, we found that glycolysis-related genes (i.e., glucokinase and pyruvate kinase) were more suppressed in the early phase of hibernation (January) compared to the late phase (March). One week after the commencement of feeding in April, expression levels of most genes returned to levels comparable to those seen in June, but β-oxidation-related genes were still up-regulated during this period. These results suggest that the modulation of gene expression is not static, but changes throughout the hibernation period. The transcriptional modulation during hibernation represents a unique physiological adaptation to prolonged fasting in bears. Copyright © 2012 Elsevier Inc. All rights reserved.

  10. Stimulation of glucose phosphorylation by fructose in isolated rat hepatocytes.

    Science.gov (United States)

    Van Schaftingen, E; Vandercammen, A

    1989-01-15

    The phosphorylation of glucose was measured by the formation of [3H]H2O from [2-3H]glucose in suspensions of freshly isolated rat hepatocytes. Fructose (0.2 mM) stimulated 2-4-fold the rate of phosphorylation of 5 mM glucose although not of 40 mM glucose, thus increasing the apparent affinity of the glucose phosphorylating system. A half-maximal stimulatory effect was observed at about 50 microM fructose. Stimulation was maximal 5 min after addition of the ketose and was stable for at least 40 min, during which period 60% of the fructose was consumed. The effect of fructose was reversible upon removal of the ketose. Sorbitol and tagatose were as potent as fructose in stimulating the phosphorylation of 5 mM glucose. D-Glyceraldehyde also had a stimulatory effect but at tenfold higher concentrations. In contrast, dihydroxyacetone had no significant effect and glycerol inhibited the detritiation of glucose. Oleate did not affect the phosphorylation of glucose, even in the presence of fructose, although it stimulated the formation of ketone bodies severalfold, indicating that it was converted to its acyl-CoA derivative. These results allow the conclusion that fructose stimulates glucokinase in the intact hepatocyte. They also suggest that this effect is mediated through the formation of fructose 1-phosphate, which presumably interacts with a competitive inhibitor of glucokinase other than long-chain acyl-CoAs.

  11. Hypolipidemic and hypoglycemic activities of a oleanolic acid derivative from Malva parviflora on streptozotocin-induced diabetic mice.

    Science.gov (United States)

    Gutiérrez, Rosa Martha Pérez

    2017-05-01

    One new oleanolic acid derivative, 2α,3β,23α,29α tetrahydroxyolean-12(13)-en-28-oic acid (1) was isolated from the aerial parts of Malva parviflora. Their structure was characterized by spectroscopic methods. The hypolipidemic and hypoglycemic activities of 1 was analyzed in in streptozotocin (STZ)-nicotinamide-induced type 2 diabetes in mice (MD) and type 1 diabetes in streptozotocin-induced diabetic mice (SD). Triterpene was administered orally at doses of 20 mg/kg for 4 weeks. Organ weight, body weight, glucose, fasting insulin, cholesterol-related lipid profile parameters, glutamate oxaloacetate transaminase (SGOT), glutamate pyruvate transaminase (SGPT), serum alkaline phosphatase (SALP), glucokinase, hexokinase, glucose-6-phosphatase activities and glycogen in liver were measured after 4 weeks of treatment. The results indicated that 1 regulate glucose metabolism, lipid profile, lipid peroxidation, increased body weight, glucokinase and hexokinase activities inhibited triglycerides, total cholesterol, low density lipoproteins level, SGOT, SGPT, SALP, glycogen in liver and glucose-6-phosphatase. In addition, improvement of insulin resistance and protective effect for pancreatic β-cells, also 1 may changes the expression of pro-inflammatory cytokine (IL-6 and TNF-α levels) and enzymes (PAL2, COX-2, and LOX). The results suggest that 1 has hypolipidemic and hypoglycemic, anti-inflammatory, activities, improve insulin resistance and hepatic enzymes in streptozotocin-induced diabetic mice.

  12. The anorectic effect of GLP-1 in rats is nutrient dependent.

    Directory of Open Access Journals (Sweden)

    Darleen Sandoval

    Full Text Available GLP-1-induced insulin secretion from the β-cell is dependent upon glucose availability. The purpose of the current study was to determine whether CNS GLP-1 signaling is also glucose-dependent. We found that fasting blunted the ability of 3(rd cerebroventricularly (i3vt-administered GLP-1 to reduce food intake. However, fasted animals maintained the anorexic response to melanotan II, a melanocortin receptor agonist, indicating a specific effect of fasting on GLP-1 action. We also found that i3vt administration of leptin, which is also decreased with fasting, was not able to potentiate GLP-1 action in fasted animals. However, we did find that CNS glucose sensing is important in GLP-1 action. Specifically, we found that i3vt injection of 2DG, a drug that blocks cellular glucose utilization, and AICAR which activates AMPK, both blocked GLP-1-induced reductions in food intake. To examine the role of glucokinase, an important CNS glucose sensor, we studied glucokinase-heterozygous knockout mice, but found that they responded normally to peripherally administered GLP-1 and exendin-4. Interestingly, oral, but not i3vt or IP glucose potentiated GLP-1's anorectic action. Thus, CNS and peripheral fuel sensing are both important in GLP-1-induced reductions in food intake.

  13. [Diagnosis of MODY - brief overview for clinical practice].

    Science.gov (United States)

    Urbanová, Jana; Brunerová, Ludmila; Brož, Jan

    2018-01-01

    Maturity Onset Diabetes of the Young (MODY) comprises inherited forms of diabetes mellitus caused by the mutations in the genes involved in the development, differentiation and function of beta-cells. The majority of patients with MODY remains misdiagnosed and erroneously classified as type 1 or type 2 diabetic patients. Correct MODY diagnosis is, however, essential since it enables individualization of treatment, assessment of the prognosis and identification of diabetes among patient´s relatives. Clinical presentation of MODY is highly variable and it could resemble other types of diabetes, thus identification of MODY patients might be difficult. In this review, we describe typical clinical presentation of the most common MODY subtypes, we summarize current diagnostic guidelines in confirmation of MODY and we raise the question of possible need for extension of current clinical criteria indicating a patient for molecular-genetic testing.Key words: clinical course - diagnosis - differential diagnosis - glucokinase - hepatocyte nuclear factors - MODY.

  14. Analysis of the GCK gene in 79 MODY type 2 patients: A multicenter Turkish study, mutation profile and description of twenty novel mutations.

    Science.gov (United States)

    Aykut, Ayça; Karaca, Emin; Onay, Hüseyin; Gökşen, Damla; Çetinkalp, Şevki; Eren, Erdal; Ersoy, Betül; Çakır, Esra Papatya; Büyükinan, Muammer; Kara, Cengiz; Anık, Ahmet; Kırel, Birgül; Özen, Samim; Atik, Tahir; Darcan, Şükran; Özkınay, Ferda

    2018-01-30

    Maturity onset diabetes is a genetic form of diabetes mellitus characterized by an early age at onset and several etiologic genes for this form of diabetes have been identified in many patients. Maturity onset diabetes type 2 [MODY2 (#125851)] caused by mutations in the glucokinase gene (GCK). Although its prevalence is not clear, it is estimated that 1%-2% of patients with diabetes have the monogenic form. The aim of this study was to evaluate the molecular spectrum of GCK gene mutations in 177 Turkish MODY type 2 patients. Mutations in the GCK gene were identified in 79 out of 177. All mutant alleles were identified, including 45 different GCK mutations, 20 of which were novel. Copyright © 2017. Published by Elsevier B.V.

  15. An analysis of the sequence of the BAD gene among patients with maturity-onset diabetes of the young (MODY).

    Science.gov (United States)

    Antosik, Karolina; Gnyś, Piotr; Jarosz-Chobot, Przemysława; Myśliwiec, Małgorzata; Szadkowska, Agnieszka; Małecki, Maciej; Młynarski, Wojciech; Borowiec, Maciej

    2017-01-01

    Monogenic diabetes is a rare disease caused by single gene mutations. Maturity onset diabetes of the young (MODY) is one of the major forms of monogenic diabetes recognised in the paediatric population. To date, 13 genes have been related to MODY development. The aim of the study was to analyse the sequence of the BCL2-associated agonist of cell death (BAD) gene in patients with clinical suspicion of GCK-MODY, but who were negative for glucokinase (GCK) gene mutations. A group of 122 diabetic patients were recruited from the "Polish Registry for Paediatric and Adolescent Diabetes - nationwide genetic screening for monogenic diabetes" project. The molecular testing was performed by Sanger sequencing. A total of 10 sequence variants of the BAD gene were identified in 122 analysed diabetic patients. Among the analysed patients suspected of MODY, one possible pathogenic variant was identified in one patient; however, further confirmation is required for a certain identification.

  16. Incretin hormones and maturity onset diabetes of the young - pathophysiological implications and anti-diabetic treatment potential

    DEFF Research Database (Denmark)

    Østoft, Signe Harring

    2015-01-01

    Maturity onset diabetes of the young (MODY) designates monogenic forms of non-autoimmune diabetes characterised by autosomal dominant inheritance, non-insulin dependent diabetes at onset and diagnosis often before 25 years of age. MODY constitutes genetically and clinically heterogeneous forms...... of diabetes. More than 8 different genes are known to cause MODY, among which hepatocyte nuclear factor 1 alpha (HNF1A) (MODY3) and glucokinase (GCK) (MODY2) mutations are the most common. Both forms of MODY are characterised by specific beta cell dysfunction, with patients with HNF1A-diabetes having...... a reduced insulin secretory capacity, while patients with GCK-diabetes have a glucose-sensing defect, but preserved insulin secretory capacity. Patients with MODY are effectively treated with sulphonylurea (SU) due to very high sensitivity to these drugs, but they are also prone to develop hypoglycaemia...

  17. Incretin Effect and Glucagon Responses to Oral and Intravenous Glucose in Patients with Maturity Onset Diabetes of the Young - Type 2 and Type 3

    DEFF Research Database (Denmark)

    Ostoft, Signe H; Bagger, Jonatan I; Hansen, Torben

    2014-01-01

    Maturity onset diabetes of the young (MODY) is a clinically and genetically heterogeneous subgroup of non-autoimmune diabetes, constituting 1-2% of all diabetes. Because little is known about incretin function in patients with MODY, we studied the incretin effect and hormone responses to oral...... and intravenous glucose loads in patients with glucokinase (GCK)-diabetes (MODY2) and hepatocyte nuclear factor 1α (HNF1A)-diabetes (MODY3), respectively, and in matched healthy control individuals (CTRLs). Both MODY groups exhibited glucose intolerance after oral glucose (most pronounced in patients with HNF1A-diabetes...... incretin effect and inappropriate glucagon responses, whereas incretin effect and glucagon response to oral glucose remain unaffected in GCK-diabetes, reflecting important pathogenetic differences between the two MODY forms....

  18. Phospho-BAD BH3 Mimicry Protects β Cells and Restores Functional β Cell Mass in Diabetes

    Directory of Open Access Journals (Sweden)

    Sanda Ljubicic

    2015-02-01

    Full Text Available Strategies that simultaneously enhance the survival and glucose responsiveness of insulin-producing β cells will greatly augment β cell replacement therapies in type 1 diabetes (T1D. We show that genetic and pharmacologic mimetics of the phosphorylated BCL-2 homology 3 (BH3 domain of BAD impart β-cell-autonomous protective effects in the face of stress stimuli relevant to β cell demise in T1D. Importantly, these benefits translate into improved engraftment of donor islets in transplanted diabetic mice, increased β cell viability in islet grafts, restoration of insulin release, and diabetes reversal. Survival of β cells in this setting is not merely due to the inability of phospho-BAD to suppress prosurvival BCL-2 proteins but requires its activation of the glucose-metabolizing enzyme glucokinase. Thus, BAD phospho-BH3 mimetics may prove useful in the restoration of functional β cell mass in diabetes.

  19. Studies on inorganic polyphosphate metabolism in Mycobacterium phlei. Pt. 1. The incorporation of 32P into various phosphorus fractions of M. phlei grown on normal and modified Loewenstein media

    International Nuclear Information System (INIS)

    Szymona, O.

    1974-01-01

    Mycobacterium phlei was grown on various media with radioactive orthophosphate added. At timed intervals the bacteria were fractionated and in particular fractions both total and 32 P was determined. The content of acid-insoluble polyphosphate was measured enzymatically by the use of specific glucokinase. The organism grown on normal Loewenstein medium proved to accumulate high amounts of polyphosphate which was formed in more than 50% at the expense of organic egg yolk phosphorus. In contrast, the nuclei acid phosphorus was derived to a greater extent from labeled orthophosphate. Concentration of polyphosphate was lower in the presence of either purified phosvitin or lecithin substituted for egg yolk, although lecithin ensured good growth of the bacteria. (author)

  20. GCKR variants increase triglycerides while protecting from insulin resistance in Chinese children.

    Science.gov (United States)

    Shen, Yue; Wu, Lijun; Xi, Bo; Liu, Xin; Zhao, Xiaoyuan; Cheng, Hong; Hou, Dongqing; Wang, Xingyu; Mi, Jie

    2013-01-01

    Variants in gene encoding glucokinase regulator protein (GCKR) were found to have converse effects on triglycerides and glucose metabolic traits. We aimed to investigate the influence of GCKR variants for triglycerides and glucose metabolic traits in Chinese children and adults. We genotyped two GCKR variants rs1260326 and rs1260333 in children and adults, and analyzed the association between two variants and triglycerides, glucose, insulin and HOMA-IR using linear regression model, and estimated the effect on insulin resistance using logistic regression model. Rs1260326 and rs1260333 associated with increased triglycerides in children and adults (ptriglycerides in Chinese children and adults. Triglycerides-increasing alleles of GCKR variants reduce insulin and HOMA-IR index, and protect from insulin resistance in children. Our results suggested GCKR has an effect on development of insulin resistance in Chinese children.

  1. Ferulic acid and derivatives: molecules with potential application in the pharmaceutical field

    Directory of Open Access Journals (Sweden)

    Lívia Brenelli de Paiva

    2013-09-01

    Full Text Available Ferulic acid is a phenolic acid widely distributed in the plant kingdom. It presents a wide range of potential therapeutic effects useful in the treatments of cancer, diabetes, lung and cardiovascular diseases, as well as hepatic, neuro and photoprotective effects and antimicrobial and anti-inflammatory activities. Overall, the pharmaceutical potential of ferulic acid can be attributed to its ability to scavenge free radicals. However, recent studies have revealed that ferulic acid presents pharmacological properties beyond those related to its antioxidant activity, such as the ability to competitively inhibit HMG-CoA reductase and activate glucokinase, contributing to reduce hypercholesterolemia and hyperglycemia, respectively. The present review addresses ferulic acid dietary sources, the pharmacokinetic profile, antioxidant action mechanisms and therapeutic effects in the treatment and prevention of various diseases, in order to provide a basis for understanding its mechanisms of action as well as its pharmaceutical potential.

  2. β-Cell Adaptability during Pregnancy

    DEFF Research Database (Denmark)

    Nielsen, Jens Høiriis; Horn, Signe; Kirkegaard, Jeanette S.

    2016-01-01

    Pregnancy is a physiological condition associated with β-cell mass expansion occurring in response to increased insulin demand. If the insulin resistance is not compensated by proper augmented insulin production gestational diabetes will occur. As reviewed herein, pregnancy induced hormonal changes...... have occupied scientists since the beginning of the last century where important discoveries of the hormonal regulation of metabolism during pregnancy have been accomplished. Of the multiple hormonal and metabolic changes the somatolactogenic hormones, placental lactogens (PL) and placental growth...... and function during pregnancy have been elucidated. This has identified contributions of a number of known peptide hormones and growth factors (EGF, NGF, HGF, IGFs, GLP-1) and steroid hormones (progesterone, estrogens, glucocorticoids). In addition, glucokinase has been found to be essential for the both...

  3. Studies on inorganic polyphosphate metabolism in Mycobacterium phlei. I. The incorporation of /sup 32/P into various phosphorus fractions of M. phlei grown on normal and modified Loewenstein media

    Energy Technology Data Exchange (ETDEWEB)

    Szymona, O [Akademia Medyczna, Lublin (Poland)

    1974-01-01

    Mycobacterium phlei was grown on various media with radioactive orthophosphate added. At timed intervals the bacteria were fractionated and in particular fractions both total and /sup 32/P was determined. The content of acid-insoluble polyphosphate was measured enzymatically by the use of specific glucokinase. The organism grown on normal Loewenstein medium proved to accumulate high amounts of polyphosphate which was formed in more than 50% at the expense of organic egg yolk phosphorus. In contrast, the nuclei acid phosphorus was derived to a greater extent from labeled orthophosphate. Concentration of polyphosphate was lower in the presence of either purified phosvitin or lecithin substituted for egg yolk, although lecithin ensured good growth of the bacteria.

  4. Four Susceptibility Loci for Gallstone Disease Identified in a Meta-analysis of Genome-Wide Association Studies

    DEFF Research Database (Denmark)

    Joshi, Amit D; Andersson, Charlotte; Buch, Stephan

    2016-01-01

    discovery studies (8720 cases and 55,152 controls). We performed an inverse variance weighted, fixed-effects meta-analysis of study-specific estimates to identify single-nucleotide polymorphisms that were associated independently with gallstone disease. Associations were replicated in 6489 cases and 62...... in TM4SF4 (OR, 1.12; 95% CI, 1.08-1.16; P = 6.09 × 10(-11)), rs2547231 in SULT2A1 (encodes a sulfoconjugation enzyme that acts on hydroxysteroids and cholesterol-derived sterol bile acids) (OR, 1.17; 95% CI, 1.12-1.21; P = 2.24 × 10(-10)), rs1260326 in glucokinase regulatory protein (OR, 1.12; 95% CI, 1...

  5. Liver X receptor regulates hepatic nuclear O-GlcNAc signaling and carbohydrate responsive element-binding protein activity

    DEFF Research Database (Denmark)

    Bindesbøll, Christian; Fan, Qiong; Nørgaard, Rikke C

    2015-01-01

    in response to feeding, which is believed to be mediated by insulin. We have previously shown that LXRs are targets for glucose-hexosamine-derived O-linked β-N-acetylglucosamine (O-GlcNAc) modification enhancing their ability to regulate SREBP-1c promoter activity in vitro. To elucidate insulin...... of glycolytic and lipogenic enzymes, including glucokinase (GK), SREBP-1c, ChREBPα, and the newly identified shorter isoform ChREBPβ. Furthermore, glucose-dependent increases in LXR/retinoid X receptor-regulated luciferase activity driven by the ChREBPα promoter was mediated, at least in part, by O-GlcNAc...... transferase (OGT) signaling in Huh7 cells. Moreover, we show that LXR and OGT interact and colocalize in the nucleus and that loss of LXRs profoundly reduced nuclear O-GlcNAc signaling and ChREBPα promoter binding activity in vivo. In summary, our study provides evidence that LXRs act as nutrient and glucose...

  6. Obesity induced by a pair-fed high fat sucrose diet: methylation and expression pattern of genes related to energy homeostasis

    Directory of Open Access Journals (Sweden)

    Campión Javier

    2010-06-01

    Full Text Available Abstract Background The expression of some genes controlling energy homeostasis could be regulated by epigenetic mechanisms that may play a role in body weight regulation. Thus, it is known that various nutritional factors affect DNA methylation. In order to assess whether the macronutrient composition of the diet could be related to the epigenetic regulation of gene expression and with obesity development, we investigated the effects on methylation and expression patterns of two pair-fed isocaloric diets in rats: control (rich in starch and HFS (rich in fat and sucrose. Results The pair-fed HFS diet induced higher weight gain and adiposity as compared to the controls as well as liver triglyceride accumulation and oxidative stress. Feeding the HFS diet impaired glucose tolerance and serum triglycerides and cholesterol. Liver glucokinase expression, a key glycolytic gene, remained unaltered, as well as the mRNA values of fatty acid synthase and NADH dehydrogenase (ubiquinone 1 beta subcomplex, 6 (NDUFB6 in liver and visceral adipocytes, which regulate lipogenesis and mitochondrial oxidative metabolism, respectively. Liver expression of hydroxyacyl-coenzyme A dehydrogenase (HADHB, a key gene of β-oxidation pathway, was higher in the HFS-fed animals. However, the methylation status of CpG islands in HADHB and glucokinase genes remained unchanged after feeding the HFS diet. Conclusions These results confirm that the distribution and type of macronutrients (starch vs. sucrose, and percent of fat influence obesity onset and the associated metabolic complications. HFS diets produce obesity independently of total energy intake, although apparently no epigenetic (DNA methylation changes accompanied the modifications observed in gene expression.

  7. Searching for Maturity-Onset Diabetes of the Young (MODY): When and What for?

    Science.gov (United States)

    Timsit, José; Saint-Martin, Cécile; Dubois-Laforgue, Danièle; Bellanné-Chantelot, Christine

    2016-10-01

    Maturity-onset diabetes of the young (MODY) is a group of monogenic diseases that results in primary defects in insulin secretion and dominantly inherited forms of nonautoimmune diabetes. Although many genes may be associated with monogenic diabetes, heterozygous mutations in 6 of them are responsible for the majority of cases of MODY. Glucokinase (GCK)-MODY is due to mutations in the glucokinase gene, 3 MODY subtypes are associated with mutations in the hepatocyte nuclear factor (HNF) transcription factors, and 2 others with mutations in ABCC8 and KCNJ11, which encode the subunits of the ATP-dependent potassium channel in pancreatic beta cells. GCK-MODY and HNF1A-MODY are the most common subtypes. The clinical presentation of MODY subtypes has been reported to differ according to the gene involved, and the diagnosis of MODY may be considered in various clinical circumstances. However, except in patients with GCK-MODY whose phenotype is very homogeneous, in most cases the penetrance and expressivity of a given molecular abnormality vary greatly among patients and, conversely, alterations in various genes may lead to similar phenotypes. Moreover, differential diagnosis among more common forms of diabetes may be difficult, particularly with type 2 diabetes. Thus, careful assessment of the personal and family histories of patients with diabetes is mandatory to select those in whom genetic screening is worthwhile. The diagnosis of monogenic diabetes has many consequences in terms of prognosis, therapeutics and family screening. Copyright © 2015 Canadian Diabetes Association. Published by Elsevier Inc. All rights reserved.

  8. Patterns of gene expression in carp liver after exposure to a mixture of waterborne and dietary cadmium using a custom-made microarray

    International Nuclear Information System (INIS)

    Reynders, Hans; Ven, Karlijn van der; Moens, Lotte N.; Remortel, Piet van; De Coen, Wim M.; Blust, Ronny

    2006-01-01

    Gene expression changes in carp liver tissue were studied after acute (3 and 24 h) and subchronic (7 and 28 days) exposure to a mixture of waterborne (9, 105 and 480 μg/l) and dietary (9.5, 122 and 144 μg/g) cadmium, using a custom-made microarray. Suppression subtractive hybridization-PCR (SSH-PCR) was applied to isolate a set of 643 liver genes, involved in multiple biological pathways, such as energy metabolism (e.g. glucokinase), immune response (e.g. complement C3) and stress and detoxification (e.g. cytochrome P450 2F2, glutathione-S-transferase pi). These genes were subsequently spotted on glass-slides for the construction of a custom-made microarray. Resulting microarray hybridizations indicated a highly dynamic response to cadmium exposure. At low exposure concentrations (9 μg/l through water and 9.5 μg/g dry weight through food) mostly energy-related genes (e.g. glucokinase, elastase) were influenced, while a general stress response was obvious through induction of several stress-related genes, including hemopexin and cytochrome P450 2F2, at high cadmium concentrations. In addition, fish exposed to the highest cadmium concentrations showed liver damage after 7 days of exposure, as measured by elevated alanine transaminase activity in plasma and increased liver water content (wet-to-dry weight ratio). Moreover, decreased hematocrit and growth were found at the end of the experiment. Altogether this study clearly demonstrated the importance of varying exposure conditions for the characterization of the molecular impact of cadmium and showed that microarray results can provide important information, required to unravel the molecular events and responses related to cadmium exposure

  9. Early feeding of carnivorous rainbow trout (Oncorhynchus mykiss) with a hyperglucidic diet during a short period: effect on dietary glucose utilization in juveniles.

    Science.gov (United States)

    Geurden, I; Aramendi, M; Zambonino-Infante, J; Panserat, S

    2007-06-01

    Based on the concept of nutritional programming in higher vertebrates, we tested whether an acute hyperglucidic stimulus during early life could induce a long-lasting effect on carbohydrate utilization in carnivorous rainbow trout. The trout were fed a hyperglucidic diet (60% dextrin) at two early stages of development: either at first feeding (3 days, stimulus 1) or after yolk absorption (5 days, stimulus 2). Before and after the hyperglucidic stimulus, they received a commercial diet until juvenile stage (>10 g). Fish that did not experience the hyperglucidic stimuli served as controls. The short- and long-term effects of the stimuli were evaluated by measuring the expression of five key genes involved in carbohydrate utilization: alpha-amylase, maltase (digestion), sodium-dependent glucose cotransporter (SGLT1; intestinal glucose transport), and glucokinase and glucose-6-phosphatase, involved in the utilization and production of glucose, respectively. The hyperglucidic diet rapidly increased expressions of maltase, alpha-amylase, and glucokinase in stimulus 1 fish and only of maltase in stimulus 2 fish, probably because of a lower plasticity at this later stage of development. In the final challenge test with juveniles fed a 25% dextrin diet, both digestive enzymes were upregulated in fish that had experienced the hyperglucidic stimulus at first feeding, confirming the possibility of modification of some long-term physiological functions in rainbow trout. In contrast, no persistent molecular adaptations were found for the genes involved in glucose transport or metabolism. In addition, growth and postprandial glycemia were unaffected by the stimuli. In summary, our data show that a short hyperglucidic stimulus during early trout life may permanently influence carbohydrate digestion.

  10. Collagen esterification enhances the function and survival of pancreatic β cells in 2D and 3D culture systems

    Energy Technology Data Exchange (ETDEWEB)

    Ko, Jae Hyung [Regenerative Medicine Research Center, Dalim Tissen Co., LTD., 383-93, Yonnam-Dong, Mapo-gu, Seoul (Korea, Republic of); Kim, Yang Hee [Regenerative Medicine Research Center, Dalim Tissen Co., LTD., 383-93, Yonnam-Dong, Mapo-gu, Seoul (Korea, Republic of); Asan Institute for Life Science, 388-1 Pungnap-2 Dong, Songpa-gu, Seoul (Korea, Republic of); Jeong, Seong Hee; Lee, Song [Asan Institute for Life Science, 388-1 Pungnap-2 Dong, Songpa-gu, Seoul (Korea, Republic of); Park, Si-Nae [Regenerative Medicine Research Center, Dalim Tissen Co., LTD., 383-93, Yonnam-Dong, Mapo-gu, Seoul (Korea, Republic of); Shim, In Kyong, E-mail: shimiink@gmail.com [Asan Institute for Life Science, 388-1 Pungnap-2 Dong, Songpa-gu, Seoul (Korea, Republic of); Kim, Song Cheol, E-mail: drksc@amc.seoul.kr [Asan Institute for Life Science, 388-1 Pungnap-2 Dong, Songpa-gu, Seoul (Korea, Republic of); Department of Surgery, University of Ulsan College of Medicine & Asan Medical Center, 388-1 Pungnap-2 Dong, Songpa-gu, Seoul (Korea, Republic of)

    2015-08-07

    Collagen, one of the most important components of the extracellular matrix (ECM), may play a role in the survival of pancreatic islet cells. In addition, chemical modifications that change the collagen charge profile to a net positive charge by esterification have been shown to increase the adhesion and proliferation of various cell types. The purpose of this study was to characterize and compare the effects of native collagen (NC) and esterified collagen (EC) on β cell function and survival. After isolation by the collagenase digestion technique, rat islets were cultured with NC and EC in 2 dimensional (2D) and 3 dimensional (3D) environments for a long-term duration in vitro. The cells were assessed for islet adhesion, morphology, viability, glucose-induced insulin secretion, and mRNA expression of glucose metabolism-related genes, and visualized by scanning electron microscopy (SEM). Islet cells attached tightly in the NC group, but islet cell viability was similar in both the NC and EC groups. Glucose-stimulated insulin secretion was higher in the EC group than in the NC group in both 2D and 3D culture. Furthermore, the mRNA expression levels of glucokinase in the EC group were higher than those in the NC group and were associated with glucose metabolism and insulin secretion. Finally, SEM observation confirmed that islets had more intact component cells on EC sponges than on NC sponges. These results indicate that modification of collagen may offer opportunities to improve function and viability of islet cells. - Highlights: • We changed the collagen charge profile to a net positive charge by esterification. • Islets cultured on esterified collagen improved survival in both 2D and 3D culture. • Islets cultured on esterified collagen enhanced glucose-stimulated insulin release. • High levels of glucokinase mRNA may be associated with increased insulin release.

  11. Collagen esterification enhances the function and survival of pancreatic β cells in 2D and 3D culture systems

    International Nuclear Information System (INIS)

    Ko, Jae Hyung; Kim, Yang Hee; Jeong, Seong Hee; Lee, Song; Park, Si-Nae; Shim, In Kyong; Kim, Song Cheol

    2015-01-01

    Collagen, one of the most important components of the extracellular matrix (ECM), may play a role in the survival of pancreatic islet cells. In addition, chemical modifications that change the collagen charge profile to a net positive charge by esterification have been shown to increase the adhesion and proliferation of various cell types. The purpose of this study was to characterize and compare the effects of native collagen (NC) and esterified collagen (EC) on β cell function and survival. After isolation by the collagenase digestion technique, rat islets were cultured with NC and EC in 2 dimensional (2D) and 3 dimensional (3D) environments for a long-term duration in vitro. The cells were assessed for islet adhesion, morphology, viability, glucose-induced insulin secretion, and mRNA expression of glucose metabolism-related genes, and visualized by scanning electron microscopy (SEM). Islet cells attached tightly in the NC group, but islet cell viability was similar in both the NC and EC groups. Glucose-stimulated insulin secretion was higher in the EC group than in the NC group in both 2D and 3D culture. Furthermore, the mRNA expression levels of glucokinase in the EC group were higher than those in the NC group and were associated with glucose metabolism and insulin secretion. Finally, SEM observation confirmed that islets had more intact component cells on EC sponges than on NC sponges. These results indicate that modification of collagen may offer opportunities to improve function and viability of islet cells. - Highlights: • We changed the collagen charge profile to a net positive charge by esterification. • Islets cultured on esterified collagen improved survival in both 2D and 3D culture. • Islets cultured on esterified collagen enhanced glucose-stimulated insulin release. • High levels of glucokinase mRNA may be associated with increased insulin release

  12. The common P446L polymorphism in GCKR inversely modulates fasting glucose and triglyceride levels and reduces type 2 diabetes risk in the DESIR prospective general French population.

    Science.gov (United States)

    Vaxillaire, Martine; Cavalcanti-Proença, Christine; Dechaume, Aurélie; Tichet, Jean; Marre, Michel; Balkau, Beverley; Froguel, Philippe

    2008-08-01

    Hepatic glucokinase (GCK) is a key regulator of glucose storage and disposal in the liver, where its activity is competitively modulated, with respect to glucose, by binding to glucokinase regulatory protein (GCKR) in the presence of fructose 6-phosphate. Genome-wide association studies for type 2 diabetes identified GCKR as a potential locus for modulating triglyceride levels. We evaluated, in a general French population, the contribution of the GCKR rs1260326-P446L polymorphism to quantitative metabolic parameters and to dyslipidemia and hyperglycemia risk. Genotype effects of rs1260326 were studied in 4,833 participants from the prospective DESIR (Data from an Epidemiological Study on the Insulin Resistance syndrome) cohort both at inclusion and using the measurements at follow-up. The minor T-allele of rs1260326 was strongly associated with lower fasting glucose (-1.43% per T-allele; P = 8 x 10(-13)) and fasting insulin levels (-4.23%; P = 3 x 10(-7)), lower homeostasis model assessment of insulin resistance index (-5.69%; P = 1 x 10(-8)), and, conversely, higher triglyceride levels (3.41%; P = 1 x 10(-4)) during the 9-year study. These effects relate to a lower risk of hyperglycemia (odds ratio [OR] 0.79 [95% CI 0.70-0.88]; P = 4 x 10(-5)) and of incident cases during the study (hazard ratio [HR] 0.83 [0.74-0.95]; P = 0.005). Moreover, an additive effect of GCKR rs1260326(T) and GCK (-30G) alleles conferred lower fasting glycemia (P = 1 x 10(-13)), insulinemia (P = 5 x 10(-6)), and hyperglycemia risk (P = 1 x 10(-6)). GCKR-L446 carriers are protected against type 2 diabetes despite higher triglyceride levels and risk of dyslipidemia, which suggests a potential molecular mechanism by which these two components of the metabolic syndrome can be dissociated.

  13. Detection of transketolase in bone marrow-derived insulin-producing cells: benfotiamine enhances insulin synthesis and glucose metabolism.

    Science.gov (United States)

    Oh, Seh-Hoon; Witek, Rafal P; Bae, Si-Hyun; Darwiche, Houda; Jung, Youngmi; Pi, Liya; Brown, Alicia; Petersen, Bryon E

    2009-01-01

    Adult bone marrow (BM)-derived insulin-producing cells (IPCs) are capable of regulating blood glucose levels in chemically induced hyperglycemic mice. Using cell transplantation therapy, fully functional BM-derived IPCs help to mediate treatment of diabetes mellitus. Here, we demonstrate the detection of the pentose phosphate pathway enzyme, transketolase (TK), in BM-derived IPCs cultured under high-glucose conditions. Benfotiamine, a known activator of TK, was not shown to affect the proliferation of insulinoma cell line, INS-1; however, when INS-1 cells were cultured with oxythiamine, an inhibitor of TK, cell proliferation was suppressed. Treatment with benfotiamine activated glucose metabolism in INS-1 cells in high-glucose culture conditions, and appeared to maximize the BM-derived IPCs ability to synthesize insulin. Benfotiamine was not shown to induce the glucose receptor Glut-2, however it was shown to activate glucokinase, the enzyme responsible for conversion of glucose to glucose-6-phosphate. Furthermore, benfotiamine-treated groups showed upregulation of the downstream glycolytic enzyme, glyceraldehyde phosphate dehydrogenase (GAPDH). However, in cells where the pentose phosphate pathway was blocked by oxythiamine treatment, there was a clear downregulation of Glut-2, glucokinase, insulin, and GAPDH. When benfotiamine was used to treat mice transplanted with BM-derived IPCs transplanted, their glucose level was brought to a normal range. The glucose challenge of normal mice treated with benfotiamine lead to rapidly normalized blood glucose levels. These results indicate that benfotiamine activates glucose metabolism and insulin synthesis to prevent glucose toxicity caused by high concentrations of blood glucose in diabetes mellitus.

  14. Detection of Transketolase in Bone Marrow—Derived Insulin-Producing Cells: Benfotiamine Enhances Insulin Synthesis and Glucose Metabolism

    Science.gov (United States)

    Witek, Rafal P.; Bae, Si-Hyun; Darwiche, Houda; Jung, Youngmi; Pi, Liya; Brown, Alicia; Petersen, Bryon E.

    2009-01-01

    Adult bone marrow (BM)-derived insulin-producing cells (IPCs) are capable of regulating blood glucose levels in chemically induced hyperglycemic mice. Using cell transplantation therapy, fully functional BM-derived IPCs help to mediate treatment of diabetes mellitus. Here, we demonstrate the detection of the pentose phosphate pathway enzyme, transketolase (TK), in BM-derived IPCs cultured under high-glucose conditions. Benfotiamine, a known activator of TK, was not shown to affect the proliferation of insulinoma cell line, INS-1; however, when INS-1 cells were cultured with oxythiamine, an inhibitor of TK, cell proliferation was suppressed. Treatment with benfotiamine activated glucose metabolism in INS-1 cells in high-glucose culture conditions, and appeared to maximize the BM-derived IPCs ability to synthesize insulin. Benfotiamine was not shown to induce the glucose receptor Glut-2, however it was shown to activate glucokinase, the enzyme responsible for conversion of glucose to glucose-6-phosphate. Furthermore, benfotiamine-treated groups showed upregulation of the downstream glycolytic enzyme, glyceraldehyde phosphate dehydrogenase (GAPDH). However, in cells where the pentose phosphate pathway was blocked by oxythiamine treatment, there was a clear downregulation of Glut-2, glucokinase, insulin, and GAPDH. When benfotiamine was used to treat mice transplanted with BM-derived IPCs transplanted, their glucose level was brought to a normal range. The glucose challenge of normal mice treated with benfotiamine lead to rapidly normalized blood glucose levels. These results indicate that benfotiamine activates glucose metabolism and insulin synthesis to prevent glucose toxicity caused by high concentrations of blood glucose in diabetes mellitus. PMID:18393672

  15. Bile acid sequestration reduces plasma glucose levels in db/db mice by increasing its metabolic clearance rate.

    Directory of Open Access Journals (Sweden)

    Maxi Meissner

    Full Text Available AIMS/HYPOTHESIS: Bile acid sequestrants (BAS reduce plasma glucose levels in type II diabetics and in murine models of diabetes but the mechanism herein is unknown. We hypothesized that sequestrant-induced changes in hepatic glucose metabolism would underlie reduced plasma glucose levels. Therefore, in vivo glucose metabolism was assessed in db/db mice on and off BAS using tracer methodology. METHODS: Lean and diabetic db/db mice were treated with 2% (wt/wt in diet Colesevelam HCl (BAS for 2 weeks. Parameters of in vivo glucose metabolism were assessed by infusing [U-(13C]-glucose, [2-(13C]-glycerol, [1-(2H]-galactose and paracetamol for 6 hours, followed by mass isotopologue distribution analysis, and related to metabolic parameters as well as gene expression patterns. RESULTS: Compared to lean mice, db/db mice displayed an almost 3-fold lower metabolic clearance rate of glucose (p = 0.0001, a ∼300% increased glucokinase flux (p = 0.001 and a ∼200% increased total hepatic glucose production rate (p = 0.0002. BAS treatment increased glucose metabolic clearance rate by ∼37% but had no effects on glucokinase flux nor total hepatic or endogenous glucose production. Strikingly, BAS-treated db/db mice displayed reduced long-chain acylcarnitine content in skeletal muscle (p = 0.0317 but not in liver (p = 0.189. Unexpectedly, BAS treatment increased hepatic FGF21 mRNA expression 2-fold in lean mice (p = 0.030 and 3-fold in db/db mice (p = 0.002. CONCLUSIONS/INTERPRETATION: BAS induced plasma glucose lowering in db/db mice by increasing metabolic clearance rate of glucose in peripheral tissues, which coincided with decreased skeletal muscle long-chain acylcarnitine content.

  16. High glucose increases action potential firing of catecholamine neurons in the nucleus of the solitary tract by increasing spontaneous glutamate inputs.

    Science.gov (United States)

    Roberts, Brandon L; Zhu, Mingyan; Zhao, Huan; Dillon, Crystal; Appleyard, Suzanne M

    2017-09-01

    Glucose is a crucial substrate essential for cell survival and function. Changes in glucose levels impact neuronal activity and glucose deprivation increases feeding. Several brain regions have been shown to respond to glucoprivation, including the nucleus of the solitary tract (NTS) in the brain stem. The NTS is the primary site in the brain that receives visceral afferent information from the gastrointestinal tract. The catecholaminergic (CA) subpopulation within the NTS modulates many homeostatic functions including cardiovascular reflexes, respiration, food intake, arousal, and stress. However, it is not known if they respond to changes in glucose. Here we determined whether NTS-CA neurons respond to changes in glucose concentration and the mechanism involved. We found that decreasing glucose concentrations from 5 mM to 2 mM to 1 mM, significantly decreased action potential firing in a cell-attached preparation, whereas increasing it back to 5 mM increased the firing rate. This effect was dependent on glutamate release from afferent terminals and required presynaptic 5-HT 3 Rs. Decreasing the glucose concentration also decreased both basal and 5-HT 3 R agonist-induced increase in the frequency of spontaneous glutamate inputs onto NTS-CA neurons. Low glucose also blunted 5-HT-induced inward currents in nodose ganglia neurons, which are the cell bodies of vagal afferents. The effect of low glucose in both nodose ganglia cells and in NTS slices was mimicked by the glucokinase inhibitor glucosamine. This study suggests that NTS-CA neurons are glucosensing through a presynaptic mechanism that is dependent on vagal glutamate release, 5-HT 3 R activity, and glucokinase. Copyright © 2017 the American Physiological Society.

  17. Competition between pentoses and glucose during uptake and catabolism in recombinant Saccharomyces cerevisiae

    Directory of Open Access Journals (Sweden)

    Subtil Thorsten

    2012-03-01

    Full Text Available Abstract Background In mixed sugar fermentations with recombinant Saccharomyces cerevisiae strains able to ferment D-xylose and L-arabinose the pentose sugars are normally only utilized after depletion of D-glucose. This has been attributed to competitive inhibition of pentose uptake by D-glucose as pentose sugars are taken up into yeast cells by individual members of the yeast hexose transporter family. We wanted to investigate whether D-glucose inhibits pentose utilization only by blocking its uptake or also by interfering with its further metabolism. Results To distinguish between inhibitory effects of D-glucose on pentose uptake and pentose catabolism, maltose was used as an alternative carbon source in maltose-pentose co-consumption experiments. Maltose is taken up by a specific maltose transport system and hydrolyzed only intracellularly into two D-glucose molecules. Pentose consumption decreased by about 20 - 30% during the simultaneous utilization of maltose indicating that hexose catabolism can impede pentose utilization. To test whether intracellular D-glucose might impair pentose utilization, hexo-/glucokinase deletion mutants were constructed. Those mutants are known to accumulate intracellular D-glucose when incubated with maltose. However, pentose utilization was not effected in the presence of maltose. Addition of increasing concentrations of D-glucose to the hexo-/glucokinase mutants finally completely blocked D-xylose as well as L-arabinose consumption, indicating a pronounced inhibitory effect of D-glucose on pentose uptake. Nevertheless, constitutive overexpression of pentose-transporting hexose transporters like Hxt7 and Gal2 could improve pentose consumption in the presence of D-glucose. Conclusion Our results confirm that D-glucose impairs the simultaneous utilization of pentoses mainly due to inhibition of pentose uptake. Whereas intracellular D-glucose does not seem to have an inhibitory effect on pentose utilization

  18. Attenuation of nonenzymatic glycation, hyperglycemia, and hyperlipidemia in streptozotocin-induced diabetic rats by chloroform leaf extract of Azadirachta indica

    Science.gov (United States)

    Gutierrez, Rosa Martha Pérez; Gómez, Yolanda Gómez Y.; Guzman, Mónica Damián

    2011-01-01

    Background: The hypoglycemic effects of hexane, chloroform and methanol extracts of leaves of Azadirachta indica (AI) were evaluated by oral administration in streptozotocin-induced severe diabetic rats (SD). Materials and Methods: The effect of chronic oral administration of the extract for 28 days was evaluated in streptozotozin diabetic rats. Lipid peroxidation, glycogen content of liver and skeletal muscles, insulin, superoxide dismutase (SOD), catalase (CAT), glutathione (GSH), oxidized glutathione (GSSG) levels were determined. In addition, advanced glycation end product formation (AGEs) was evaluated. Results: The most active extracts were obtained with chloroform. Chloroform extract from AI shows increased levels of SOD, GSH, GSSG and CAT, hepatic glycogen content, glucose-6-phosphatase and insulin plasma levels, which also decreased the glucokinase (GK), lipid peroxidation and insulin resistance. The chloroform extract exhibited significant inhibitory activity against advanced glycation end product formation with an IC50 average range of 79.1 mg/ml. Conclusion: Azadirachta indica can improve hyperlipidemia and hyperinsulinema in streptozocin-induced diabetic rats and, therefore, AI can be potentially considered to be an antidiabetic-safe agent. PMID:21969798

  19. Recent Advances in Fluorescent Arylboronic Acids for Glucose Sensing

    Directory of Open Access Journals (Sweden)

    Jon Stefan Hansen

    2013-12-01

    Full Text Available Continuous glucose monitoring (CGM is crucial in order to avoid complications caused by change in blood glucose for patients suffering from diabetes mellitus. The long-term consequences of high blood glucose levels include damage to the heart, eyes, kidneys, nerves and other organs, among others, caused by malign glycation of vital protein structures. Fluorescent monitors based on arylboronic acids are promising candidates for optical CGM, since arylboronic acids are capable of forming arylboronate esters with 1,2-cis-diols or 1,3-diols fast and reversibly, even in aqueous solution. These properties enable arylboronic acid dyes to provide immediate information of glucose concentrations. Thus, the replacement of the commonly applied semi-invasive and non-invasive techniques relying on glucose binding proteins, such as concanavalin A, or enzymes, such as glucose oxidase, glucose dehydrogenase and hexokinases/glucokinases, might be possible. The recent progress in the development of fluorescent arylboronic acid dyes will be emphasized in this review.

  20. Dietary fatty acids modulate associations between genetic variants and circulating fatty acids in plasma and erythrocyte membranes: meta-analysis of 9 studies in the CHARGE consortium

    Science.gov (United States)

    Smith, Caren E.; Follis, Jack L.; Nettleton, Jennifer A.; Foy, Millennia; Wu, Jason H.Y.; Ma, Yiyi; Tanaka, Toshiko; Manichakul, Ani W.; Wu, Hongyu; Chu, Audrey Y.; Steffen, Lyn M.; Fornage, Myriam; Mozaffarian, Dariush; Kabagambe, Edmond K.; Ferruci, Luigi; da Chen, Yii-Der I; Rich, Stephen S.; Djoussé, Luc; Ridker, Paul M.; Tang, Weihong; McKnight, Barbara; Tsai, Michael Y.; Bandinelli, Stefania; Rotter, Jerome I.; Hu, Frank B.; Chasman, Daniel I.; Psaty, Bruce M.; Arnett, Donna K.; King, Irena B.; Sun, Qi; Wang, Lu; Lumley, Thomas; Chiuve, Stephanie E.; Siscovick, David S; Ordovás, José M.; Lemaitre, Rozenn N.

    2015-01-01

    Scope Tissue concentrations of omega-3 fatty acids may reduce cardiovascular disease risk, and genetic variants are associated with circulating fatty acids concentrations. Whether dietary fatty acids interact with genetic variants to modify circulating omega-3 fatty acids is unclear. Objective We evaluated interactions between genetic variants and fatty acid intakes for circulating alpha-linoleic acid (ALA), eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and docosapentaenoic acid (DPA). Methods and Results We conducted meta-analyses (N to 11,668) evaluating interactions between dietary fatty acids and genetic variants (rs174538 and rs174548 in FADS1 (fatty acid desaturase 1), rs7435 in AGPAT3 (1-acyl-sn-glycerol-3-phosphate), rs4985167 in PDXDC1 (pyridoxal-dependent decarboxylase domain-containing 1), rs780094 in GCKR (glucokinase regulatory protein) and rs3734398 in ELOVL2 (fatty acid elongase 2)). Stratification by measurement compartment (plasma vs. erthyrocyte) revealed compartment-specific interactions between FADS1 rs174538 and rs174548 and dietary ALA and linoleic acid for DHA and DPA. Conclusion Our findings reinforce earlier reports that genetically-based differences in circulating fatty acids may be partially due to differences in the conversion of fatty acid precursors. Further, fatty acids measurement compartment may modify gene-diet relationships, and considering compartment may improve the detection of gene-fatty acids interactions for circulating fatty acid outcomes. PMID:25626431

  1. An in-silico investigation of anti-Chagas phytochemicals.

    Science.gov (United States)

    McCulley, Stephanie F; Setzer, William N

    2014-01-01

    Over 18 million people in tropical and subtropical America are afflicted by American trypanosomiasis or Chagas disease. In humans, symptoms of the disease include fever, swelling, and heart and brain damage, usually leading to death. There is currently no effective treatment for this disease. Plant products continue to be rich sources of clinically useful drugs, and the biodiversity of the Neotropics suggests great phytomedicinal potential. Screening programs have revealed numerous plant species and phytochemical agents that have shown in-vitro or in-vivo antitrypanosomal activity, but the biochemical targets of these phytochemicals are not known. In this work, we present a molecular docking analysis of Neotropical phytochemicals, which have already demonstrated antiparasitic activity against Trypanosoma cruzi, with potential druggable protein targets of the parasite. Several protein targets showed in-silico selectivity for trypanocidal phytochemicals, including trypanothione reductase, pteridine reductase 2, lipoamide dehydrogenase, glucokinase, dihydroorotate dehydrogenase, cruzain, dihydrofolate-reductase/thymidylate-synthase, and farnesyl diphosphate synthase. Some of the phytochemical ligands showed notable docking preference for trypanothione reductase, including flavonoids, fatty-acid-derived oxygenated hydrocarbons, geranylgeraniol and the lignans ganschisandrine and eupomatenoid-6.

  2. Interaction Between the Central and Peripheral Effects of Insulin in Controlling Hepatic Glucose Metabolism in the Conscious Dog

    Science.gov (United States)

    Ramnanan, Christopher J.; Kraft, Guillaume; Smith, Marta S.; Farmer, Ben; Neal, Doss; Williams, Phillip E.; Lautz, Margaret; Farmer, Tiffany; Donahue, E. Patrick; Cherrington, Alan D.; Edgerton, Dale S.

    2013-01-01

    The importance of hypothalamic insulin action to the regulation of hepatic glucose metabolism in the presence of a normal liver/brain insulin ratio (3:1) is unknown. Thus, we assessed the role of central insulin action in the response of the liver to normal physiologic hyperinsulinemia over 4 h. Using a pancreatic clamp, hepatic portal vein insulin delivery was increased three- or eightfold in the conscious dog. Insulin action was studied in the presence or absence of intracerebroventricularly mediated blockade of hypothalamic insulin action. Euglycemia was maintained, and glucagon was clamped at basal. Both the molecular and metabolic aspects of insulin action were assessed. Blockade of hypothalamic insulin signaling did not alter the insulin-mediated suppression of hepatic gluconeogenic gene transcription but blunted the induction of glucokinase gene transcription and completely blocked the inhibition of glycogen synthase kinase-3β gene transcription. Thus, central and peripheral insulin action combined to control some, but not other, hepatic enzyme programs. Nevertheless, inhibition of hypothalamic insulin action did not alter the effects of the hormone on hepatic glucose flux (production or uptake). These data indicate that brain insulin action is not a determinant of the rapid (<4 h) inhibition of hepatic glucose metabolism caused by normal physiologic hyperinsulinemia in this large animal model. PMID:23011594

  3. Metabolic sensing neurons and the control of energy homeostasis.

    Science.gov (United States)

    Levin, Barry E

    2006-11-30

    The brain and periphery carry on a constant conversation; the periphery informs the brain about its metabolic needs and the brain provides for these needs through its control of somatomotor, autonomic and neurohumoral pathways involved in energy intake, expenditure and storage. Metabolic sensing neurons are the integrators of a variety of metabolic, humoral and neural inputs from the periphery. Such neurons, originally called "glucosensing", also respond to fatty acids, hormones and metabolites from the periphery. They are integrated within neural pathways involved in the regulation of energy homeostasis. Unlike most neurons, they utilize glucose and other metabolites as signaling molecules to regulate their membrane potential and firing rate. For glucosensing neurons, glucokinase acts as the rate-limiting step in glucosensing while the pathways that mediate responses to metabolites like lactate, ketone bodies and fatty acids are less well characterized. Many metabolic sensing neurons also respond to insulin and leptin and other peripheral hormones and receive neural inputs from peripheral organs. Each set of afferent signals arrives with different temporal profiles and by different routes and these inputs are summated at the level of the membrane potential to produce a given neural firing pattern. In some obese individuals, the relative sensitivity of metabolic sensing neurons to various peripheral inputs is genetically reduced. This may provide one mechanism underlying their propensity to become obese when exposed to diets high in fat and caloric density. Thus, metabolic sensing neurons may provide a potential therapeutic target for the treatment of obesity.

  4. Evaluation of 90-day Repeated Dose Oral Toxicity, Glycometabolism, Learning and Memory Ability, and Related Enzyme of Chromium Malate Supplementation in Sprague-Dawley Rats.

    Science.gov (United States)

    Feng, Weiwei; Wu, Huiyu; Li, Qian; Zhou, Zhaoxiang; Chen, Yao; Zhao, Ting; Feng, Yun; Mao, Guanghua; Li, Fang; Yang, Liuqing; Wu, Xiangyang

    2015-11-01

    Our previous study showed that chromium malate improved the regulation of blood glucose in mice with alloxan-induced diabetes. The present study was designed to evaluate the 90-day oral toxicity of chromium malate in Sprague-Dawley rats. The present study inspected the effect of chromium malate on glycometabolism, glycometabolism-related enzymes, lipid metabolism, and learning and memory ability in metabolically healthy Sprague-Dawley rats. The results showed that all rats survived and pathological, toxic, feces, and urine changes were not observed. Chromium malate did not cause measurable damage on liver, brain, and kidney. The fasting blood glucose, serum insulin, insulin resistance index, C-peptide, hepatic glycogen, glucose-6-phosphate dehydrogenase, glucokinase, total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and triglyceride levels of normal rats in chromium malate groups had no significant change when compared with control group and chromium picolinate group under physiologically relevant conditions. The serum and organ content of Cr in chromium malate groups had no significant change compared with control group. No significant changes were found in morris water maze test and superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and true choline esterase (TChE) activity. The results indicated that supplementation with chromium malate did not cause measurable toxicity and has no obvious effect on glycometabolism and related enzymes, learning and memory ability, and related enzymes and lipid metabolism of female and male rats. The results of this study suggest that chromium malate is safe for human consumption.

  5. Molecular Dynamics Simulations and Kinetic Measurements to Estimate and Predict Protein-Ligand Residence Times.

    Science.gov (United States)

    Mollica, Luca; Theret, Isabelle; Antoine, Mathias; Perron-Sierra, Françoise; Charton, Yves; Fourquez, Jean-Marie; Wierzbicki, Michel; Boutin, Jean A; Ferry, Gilles; Decherchi, Sergio; Bottegoni, Giovanni; Ducrot, Pierre; Cavalli, Andrea

    2016-08-11

    Ligand-target residence time is emerging as a key drug discovery parameter because it can reliably predict drug efficacy in vivo. Experimental approaches to binding and unbinding kinetics are nowadays available, but we still lack reliable computational tools for predicting kinetics and residence time. Most attempts have been based on brute-force molecular dynamics (MD) simulations, which are CPU-demanding and not yet particularly accurate. We recently reported a new scaled-MD-based protocol, which showed potential for residence time prediction in drug discovery. Here, we further challenged our procedure's predictive ability by applying our methodology to a series of glucokinase activators that could be useful for treating type 2 diabetes mellitus. We combined scaled MD with experimental kinetics measurements and X-ray crystallography, promptly checking the protocol's reliability by directly comparing computational predictions and experimental measures. The good agreement highlights the potential of our scaled-MD-based approach as an innovative method for computationally estimating and predicting drug residence times.

  6. Serum deprivation induces glucose response and intercellular coupling in human pancreatic adenocarcinoma PANC-1 cells.

    Science.gov (United States)

    Hiram-Bab, Sahar; Shapira, Yuval; Gershengorn, Marvin C; Oron, Yoram

    2012-03-01

    This study aimed to investigate whether the previously described differentiating islet-like aggregates of human pancreatic adenocarcinoma cells (PANC-1) develop glucose response and exhibit intercellular communication. Fura 2-loaded PANC-1 cells in serum-free medium were assayed for changes in cytosolic free calcium ([Ca]i) induced by depolarization, tolbutamide inhibition of K(ATP) channels, or glucose. Dye transfer, assayed by confocal microscopy or by FACS, was used to detect intercellular communication. Changes in messenger RNA (mRNA) expression of genes of interest were assessed by quantitative real-time polymerase chain reaction. Proliferation was assayed by the MTT method. Serum-deprived PANC-1 cell aggregates developed [Ca]i response to KCl, tolbutamide, or glucose. These responses were accompanied by 5-fold increase in glucokinase mRNA level and, to a lesser extent, of mRNAs for K(ATP) and L-type calcium channels, as well as increase in mRNA levels of glucagon and somatostatin. Trypsin, a proteinase-activated receptor 2 agonist previously shown to enhance aggregation, modestly improved [Ca]i response to glucose. Glucose-induced coordinated [Ca]i oscillations and dye transfer demonstrated the emergence of intercellular communication. These findings suggest that PANC-1 cells, a pancreatic adenocarcinoma cell line, can be induced to express a differentiated phenotype in which cells exhibit response to glucose and form a functional syncytium similar to those observed in pancreatic islets.

  7. HDL cholesterol as a diagnostic tool for clinical differentiation of GCK-MODY from HNF1A-MODY and type 1 diabetes in children and young adults.

    Science.gov (United States)

    Fendler, Wojciech; Borowiec, Maciej; Antosik, Karolina; Szadkowska, Agnieszka; Deja, Grazyna; Jarosz-Chobot, Przemyslawa; Mysliwiec, Malgorzata; Wyka, Krystyna; Pietrzak, Iwona; Skupien, Jan; Malecki, Maciej T; Mlynarski, Wojciech

    2011-09-01

    Confirmation of monogenic diabetes caused by glucokinase mutations (GCK-MODY) allows pharmacogenetic intervention in the form of insulin discontinuation. This is especially important among paediatric and young adult populations where GCK-MODY is most prevalent. The study evaluated the utility of lipid parameters in screening for patients with GCK-MODY. Eighty-nine children with type 1 diabetes and 68 with GCK-MODY were screened for triglyceride (TG), total and HDL cholesterol levels. Standardization against a control group of 171 healthy children was applied to eliminate the effect of development. Clinical applicability and cut-off value were evaluated in all available patients with GCK-MODY (n = 148), hepatocyte nuclear factor 1-alpha-MODY (HNF1A MODY) (n = 37) or type 1 diabetes (n = 221). Lower lipid parameter values were observed in GCK-MODY than in patients with type 1 diabetes. Standard deviation scores were -0·22 ± 2·24 vs 1·31 ± 2·17 for HDL cholesterol (P MODY selection [sensitivity 87%, specificity 54%, negative predictive value (NPV) 86%, positive PV 56%]. A threshold HDL concentration of 1·56 mm offered significantly better diagnostic efficiency than total cholesterol (cut-off value 4·51 mm; NPV 80%; PPV 38%; P MODY and differentiation from T1DM and HNF1A-MODY, regardless of treatment or metabolic control. © 2011 Blackwell Publishing Ltd.

  8. Phenotypical aspects of maturity-onset diabetes of the young (MODY diabetes) in comparison with Type 2 diabetes mellitus (T2DM) in children and adolescents: experience from a large multicentre database.

    Science.gov (United States)

    Schober, E; Rami, B; Grabert, M; Thon, A; Kapellen, Th; Reinehr, Th; Holl, R W

    2009-05-01

    To analyse and compare clinical characteristics in young patients with maturity-onset diabetes of the young (MODY) and Type 2 diabetes mellitus (T2DM). We conducted an observational investigation using the DPV-Wiss database containing clinical data on 40 757 diabetic patients MODY (0.83%); 562 patients were diagnosed as T2DM (1.4%). In 20% of cases, the diagnosis of MODY was based on clinical findings only. Of the 272 subjects where genetic testing was available, 3% did not carry mutations in the three examined MODY genes. Glucokinase-MODY was commoner than HNF1A-MODY and HNF4A-MODY. Age at diagnosis was younger in MODY patients. The body mass index of T2DM was significantly higher compared with all MODY subgroups. Macrovascular risk factors such as dyslipidaemia and hypertension were commoner in T2DM, but 23% of MODY patients had dyslipidaemia and 10% hypertension. Glycaemic control was within the therapeutic target (HbA(1c) MODY and 70% of T2DM patients. The prevalence of MODY in children and adolescents in Germany and Austria is lower than that of T2DM in this age group. Dyslipidaemia and hypertension are less frequent in MODY compared with T2DM patients, but do occur.

  9. Maturity-Onset Diabetes of the Young (MODY): Making the Right Diagnosis to Optimize Treatment.

    Science.gov (United States)

    Amed, Shazhan; Oram, Richard

    2016-10-01

    Maturity onset diabetes of the young (MODY) is a rare but increasingly recognized cause of diabetes in young people. It is a monogenic disorder that typically presents at MODY are caused by mutations in glucokinase and hepatic nuclear factor 1 alpha or 4 alpha genes and account for almost 80% of cases of MODY. MODY is commonly misdiagnosed as type 1 or type 2 diabetes and, as a result, patients are often inappropriately managed with insulin when they can be more effectively managed with oral sulfonylureas. Therefore, making the right diagnosis is critical for effective treatment as well as for genetic counselling and, more important, for patients' quality of life. In this review, we aim to raise awareness about MODY among diabetes clinicians by describing key clinical and laboratory features of the most common forms of MODY, outlining features that might help to differentiate MODY from type 1 and type 2 diabetes and providing information about clinical tests and tools that might assist in identifying patients who are most likely to benefit from molecular genetic testing. Copyright © 2016 Canadian Diabetes Association. Published by Elsevier Inc. All rights reserved.

  10. Maturity-onset diabetes of the young (MODY): an update.

    Science.gov (United States)

    Anık, Ahmet; Çatlı, Gönül; Abacı, Ayhan; Böber, Ece

    2015-03-01

    Maturity-onset diabetes of the young (MODY) is a group of monogenic disorders characterized by autosomal dominantly inherited non-insulin dependent form of diabetes classically presenting in adolescence or young adults before the age of 25 years. MODY is a rare cause of diabetes (1% of all cases) and is frequently misdiagnosed as Type 1 diabetes (T1DM) or Type 2 diabetes (T2DM). A precise molecular diagnosis is essential because it leads to optimal treatment of the patients and allows early diagnosis for their asymptomatic family members. Mutations in the glucokinase (GCK) (MODY 2) and hepatocyte nuclear factor (HNF)1A/4A (MODY 3 and MODY 1) genes are the most common causes of MODY. GCK mutations cause a mild, asymptomatic, and stable fasting hyperglycemia usually requiring no specific treatment. However, mutations in the HNF1A and HNF4A cause a progressive pancreatic β-cell dysfunction and hyperglycemia that can result in microvascular complications. Sulfonylureas are effective in these patients by acting on adenosine triphosphate (ATP)-sensitive potassium channels, although insulin therapy may be required later in life. Mutations in the HNF1B (MODY 5) is associated with pancreatic agenesis, renal abnormalities, genital tract malformations, and liver dysfunction. Compared to MODY 1, 2, 3, and 5, the remaining subtypes of MODY have a much lower prevalence. In this review, we summarize the main clinical and laboratory characteristics of the common and rarer causes of MODY.

  11. Genetic Testing of Maturity-Onset Diabetes of the Young Current Status and Future Perspectives

    Directory of Open Access Journals (Sweden)

    Parveena Firdous

    2018-05-01

    Full Text Available Diabetes is a global epidemic problem growing exponentially in Asian countries posing a serious threat. Among diabetes, maturity-onset diabetes of the young (MODY is a heterogeneous group of monogenic disorders that occurs due to β cell dysfunction. Genetic defects in the pancreatic β-cells result in the decrease of insulin production required for glucose utilization thereby lead to early-onset diabetes (often <25 years. It is generally considered as non-insulin dependent form of diabetes and comprises of 1–5% of total diabetes. Till date, 14 genes have been identified and mutation in them may lead to MODY. Different genetic testing methodologies like linkage analysis, restriction fragment length polymorphism, and DNA sequencing are used for the accurate and correct investigation of gene mutations associated with MODY. The next-generation sequencing has emerged as one of the most promising and effective tools to identify novel mutated genes related to MODY. Diagnosis of MODY is mainly relying on the sequential screening of the three marker genes like hepatocyte nuclear factor 1 alpha (HNF1α, hepatocyte nuclear factor 4 alpha (HNF4α, and glucokinase (GCK. Interestingly, MODY patients can be managed by diet alone for many years and may also require minimal doses of sulfonylureas. The primary objective of this article is to provide a review on current status of MODY, its prevalence, genetic testing/diagnosis, possible treatment, and future perspective.

  12. High-sensitivity CRP discriminates HNF1A-MODY from other subtypes of diabetes.

    Science.gov (United States)

    McDonald, Tim J; Shields, Beverley M; Lawry, Jane; Owen, Katharine R; Gloyn, Anna L; Ellard, Sian; Hattersley, Andrew T

    2011-08-01

    Maturity-onset diabetes of the young (MODY) as a result of mutations in hepatocyte nuclear factor 1-α (HNF1A) is often misdiagnosed as type 1 diabetes or type 2 diabetes. Recent work has shown that high-sensitivity C-reactive protein (hs-CRP) levels are lower in HNF1A-MODY than type 1 diabetes, type 2 diabetes, or glucokinase (GCK)-MODY. We aim to replicate these findings in larger numbers and other MODY subtypes. hs-CRP levels were assessed in 750 patients (220 HNF1A, 245 GCK, 54 HNF4-α [HNF4A], 21 HNF1-β (HNF1B), 53 type 1 diabetes, and 157 type 2 diabetes). hs-CRP was lower in HNF1A-MODY (median [IQR] 0.3 [0.1-0.6] mg/L) than type 2 diabetes (1.40 [0.60-3.45] mg/L; P MODY (1.45 [0.46-2.88] mg/L; P MODY (0.60 [0.30-1.80] mg/L; P MODY (0.60 [0.10-2.8] mg/L; P = 0.07). hs-CRP discriminated HNF1A-MODY from type 2 diabetes with hs-CRP MODY than other forms of diabetes and may be used as a biomarker to select patients for diagnostic HNF1A genetic testing.

  13. Genetic and bioinformatics analysis of four novel GCK missense variants detected in Caucasian families with GCK-MODY phenotype.

    Science.gov (United States)

    Costantini, S; Malerba, G; Contreas, G; Corradi, M; Marin Vargas, S P; Giorgetti, A; Maffeis, C

    2015-05-01

    Heterozygous loss-of-function mutations in the glucokinase (GCK) gene cause maturity-onset diabetes of the young (MODY) subtype GCK (GCK-MODY/MODY2). GCK sequencing revealed 16 distinct mutations (13 missense, 1 nonsense, 1 splice site, and 1 frameshift-deletion) co-segregating with hyperglycaemia in 23 GCK-MODY families. Four missense substitutions (c.718A>G/p.Asn240Asp, c.757G>T/p.Val253Phe, c.872A>C/p.Lys291Thr, and c.1151C>T/p.Ala384Val) were novel and a founder effect for the nonsense mutation (c.76C>T/p.Gln26*) was supposed. We tested whether an accurate bioinformatics approach could strengthen family-genetic evidence for missense variant pathogenicity in routine diagnostics, where wet-lab functional assays are generally unviable. In silico analyses of the novel missense variants, including orthologous sequence conservation, amino acid substitution (AAS)-pathogenicity predictors, structural modeling and splicing predictors, suggested that the AASs and/or the underlying nucleotide changes are likely to be pathogenic. This study shows how a careful bioinformatics analysis could provide effective suggestions to help molecular-genetic diagnosis in absence of wet-lab validations. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  14. Mutations in HNF1A result in marked alterations of plasma glycan profile

    DEFF Research Database (Denmark)

    Thanabalasingham, Gaya; Huffman, Jennifer E; Kattla, Jayesh J

    2013-01-01

    A recent genome-wide association study identified hepatocyte nuclear factor 1-α (HNF1A) as a key regulator of fucosylation. We hypothesized that loss-of-function HNF1A mutations causal for maturity-onset diabetes of the young (MODY) would display altered fucosylation of N-linked glycans on plasma...... proteins and that glycan biomarkers could improve the efficiency of a diagnosis of HNF1A-MODY. In a pilot comparison of 33 subjects with HNF1A-MODY and 41 subjects with type 2 diabetes, 15 of 29 glycan measurements differed between the two groups. The DG9-glycan index, which is the ratio of fucosylated...... to nonfucosylated triantennary glycans, provided optimum discrimination in the pilot study and was examined further among additional subjects with HNF1A-MODY (n = 188), glucokinase (GCK)-MODY (n = 118), hepatocyte nuclear factor 4-α (HNF4A)-MODY (n = 40), type 1 diabetes (n = 98), type 2 diabetes (n = 167...

  15. Postprandial incretin and islet hormone responses and dipeptidyl-peptidase 4 enzymatic activity in patients with maturity onset diabetes of the young

    DEFF Research Database (Denmark)

    Østoft, Signe Harring; Bagger, Jonatan Ising; Hansen, Torben

    2015-01-01

    Objective: The role of the incretin hormones in the pathophysiology of maturity onset diabetes of the young (MODY) is unclear. Design: We studied the postprandial plasma responses of glucagon, incretin hormones (glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP......)), and dipeptidyl-peptidase 4 (DPP-4) enzymatic activity in patients with glucokinase (GCK)-diabetes (MODY2), hepatocyte nuclear factor 1α (HNF1A)-diabetes (MODY3), and in matched healthy individuals (CTRLs). Subjects and methods: Ten patients with GCK-diabetes (age: 43±5 years; BMI: 24±2 kg/m2; FPG: 7.1±0.3 mmol....../l: HbA1c: 6.6±0.2%), 10 patients with HNF1A-diabetes (age: 31±3 years (mean ± SEM); body mass index (BMI): 24±1 kg/m2; fasting plasma glucose (FPG): 8.9±0.8 mmol/l; haemoglobin A1c (HbA1c): 7.0±0.3%), and 10 CTRLs (age: 40±5 years; BMI: 24±1 kg/m2; FPG: 5.1±0.1 mmol/l; HbA1c: 5.3±0.1%) were examined...

  16. Genetic Testing of Maturity-Onset Diabetes of the Young Current Status and Future Perspectives

    Science.gov (United States)

    Firdous, Parveena; Nissar, Kamran; Ali, Sajad; Ganai, Bashir Ahmad; Shabir, Uzma; Hassan, Toyeeba; Masoodi, Shariq Rashid

    2018-01-01

    Diabetes is a global epidemic problem growing exponentially in Asian countries posing a serious threat. Among diabetes, maturity-onset diabetes of the young (MODY) is a heterogeneous group of monogenic disorders that occurs due to β cell dysfunction. Genetic defects in the pancreatic β-cells result in the decrease of insulin production required for glucose utilization thereby lead to early-onset diabetes (often diabetes and comprises of 1–5% of total diabetes. Till date, 14 genes have been identified and mutation in them may lead to MODY. Different genetic testing methodologies like linkage analysis, restriction fragment length polymorphism, and DNA sequencing are used for the accurate and correct investigation of gene mutations associated with MODY. The next-generation sequencing has emerged as one of the most promising and effective tools to identify novel mutated genes related to MODY. Diagnosis of MODY is mainly relying on the sequential screening of the three marker genes like hepatocyte nuclear factor 1 alpha (HNF1α), hepatocyte nuclear factor 4 alpha (HNF4α), and glucokinase (GCK). Interestingly, MODY patients can be managed by diet alone for many years and may also require minimal doses of sulfonylureas. The primary objective of this article is to provide a review on current status of MODY, its prevalence, genetic testing/diagnosis, possible treatment, and future perspective. PMID:29867778

  17. A large multi-centre European study validates high-sensitivity C-reactive protein (hsCRP) as a clinical biomarker for the diagnosis of diabetes subtypes

    DEFF Research Database (Denmark)

    Thanabalasingham, G.; Shah, N.; Vaxillaire, M.

    2011-01-01

    CRP) levels are lower in UK patients with hepatocyte nuclear factor 1 alpha (HNF1A)-MODY than in other diabetes subtypes. In this large multi-centre study we aimed to assess the clinical validity of hsCRP as a diagnostic biomarker, examine the genotype-phenotype relationship and compare different hsCRP assays....... High-sensitivity CRP levels were analysed in individuals with HNF1A-MODY (n = 457), glucokinase (GCK)-MODY (n = 404), hepatocyte nuclear factor 4 alpha (HNF4A)-MODY (n = 54) and type 2 diabetes (n = 582) from seven European centres. Three common assays for hsCRP analysis were evaluated. We excluded 121......) a parts per thousand yenaEuro parts per thousand 0.91, p a parts per thousand currency signaEuro parts per thousand 1 x 10(-5)). Across the seven centres, the C-statistic for distinguishing HNF1A-MODY from young adult-onset type 2 diabetes ranged from 0.79 to 0.97, indicating high discriminative accuracy...

  18. The Brain–to–Pancreatic Islet Neuronal Map Reveals Differential Glucose Regulation From Distinct Hypothalamic Regions

    Science.gov (United States)

    Rosario, Wilfredo; Singh, Inderroop; Wautlet, Arnaud; Patterson, Christa; Flak, Jonathan; Becker, Thomas C.; Ali, Almas; Tamarina, Natalia; Philipson, Louis H.; Enquist, Lynn W.; Myers, Martin G.

    2016-01-01

    The brain influences glucose homeostasis, partly by supplemental control over insulin and glucagon secretion. Without this central regulation, diabetes and its complications can ensue. Yet, the neuronal network linking to pancreatic islets has never been fully mapped. Here, we refine this map using pseudorabies virus (PRV) retrograde tracing, indicating that the pancreatic islets are innervated by efferent circuits that emanate from the hypothalamus. We found that the hypothalamic arcuate nucleus (ARC), ventromedial nucleus (VMN), and lateral hypothalamic area (LHA) significantly overlap PRV and the physiological glucose-sensing enzyme glucokinase. Then, experimentally lowering glucose sensing, specifically in the ARC, resulted in glucose intolerance due to deficient insulin secretion and no significant effect in the VMN, but in the LHA it resulted in a lowering of the glucose threshold that improved glucose tolerance and/or improved insulin sensitivity, with an exaggerated counter-regulatory response for glucagon secretion. No significant effect on insulin sensitivity or metabolic homeostasis was noted. Thus, these data reveal novel direct neuronal effects on pancreatic islets and also render a functional validation of the brain-to-islet neuronal map. They also demonstrate that distinct regions of the hypothalamus differentially control insulin and glucagon secretion, potentially in partnership to help maintain glucose homeostasis and guard against hypoglycemia. PMID:27207534

  19. The Brain-to-Pancreatic Islet Neuronal Map Reveals Differential Glucose Regulation From Distinct Hypothalamic Regions.

    Science.gov (United States)

    Rosario, Wilfredo; Singh, Inderroop; Wautlet, Arnaud; Patterson, Christa; Flak, Jonathan; Becker, Thomas C; Ali, Almas; Tamarina, Natalia; Philipson, Louis H; Enquist, Lynn W; Myers, Martin G; Rhodes, Christopher J

    2016-09-01

    The brain influences glucose homeostasis, partly by supplemental control over insulin and glucagon secretion. Without this central regulation, diabetes and its complications can ensue. Yet, the neuronal network linking to pancreatic islets has never been fully mapped. Here, we refine this map using pseudorabies virus (PRV) retrograde tracing, indicating that the pancreatic islets are innervated by efferent circuits that emanate from the hypothalamus. We found that the hypothalamic arcuate nucleus (ARC), ventromedial nucleus (VMN), and lateral hypothalamic area (LHA) significantly overlap PRV and the physiological glucose-sensing enzyme glucokinase. Then, experimentally lowering glucose sensing, specifically in the ARC, resulted in glucose intolerance due to deficient insulin secretion and no significant effect in the VMN, but in the LHA it resulted in a lowering of the glucose threshold that improved glucose tolerance and/or improved insulin sensitivity, with an exaggerated counter-regulatory response for glucagon secretion. No significant effect on insulin sensitivity or metabolic homeostasis was noted. Thus, these data reveal novel direct neuronal effects on pancreatic islets and also render a functional validation of the brain-to-islet neuronal map. They also demonstrate that distinct regions of the hypothalamus differentially control insulin and glucagon secretion, potentially in partnership to help maintain glucose homeostasis and guard against hypoglycemia. © 2016 by the American Diabetes Association.

  20. A Narrative Review of Potential Future Antidiabetic Drugs: Should We Expect More?

    Science.gov (United States)

    Chikara, Gaurav; Sharma, Pramod Kumar; Dwivedi, Pradeep; Charan, Jaykaran; Ambwani, Sneha; Singh, Surjit

    2018-04-01

    Prevalence of diabetes mellitus, a chronic metabolic disease characterized by hyperglycemia, is growing worldwide. The majority of the cases belong to type 2 diabetes mellitus (T2DM). Globally, India ranks second in terms of diabetes prevalence among adults. Currently available classes of therapeutic agents are used alone or in combinations but seldom achieve treatment targets. Diverse pathophysiology and the need of therapeutic agents with more favourable pharmacokinetic-pharmacodynamics profile make newer drug discoveries in the field of T2DM essential. A large number of molecules, some with novel mechanisms, are in pipeline. The essence of this review is to track and discuss these potential agents, based on their developmental stages, especially those in phase 3 or phase 2. Unique molecules are being developed for existing drug classes like insulins, DPP-4 inhibitors, GLP-1 analogues; and under newer classes like dual/pan PPAR agonists, dual SGLT1/SGLT2 inhibitors, glimins, anti-inflammatory agents, glucokinase activators, G-protein coupled receptor agonists, hybrid peptide agonists, apical sodium-dependent bile acid transporter (ASBT) inhibitors, glucagon receptor antagonists etc. The heterogeneous clinical presentation and therapeutic outcomes in phenotypically similar patients is a clue to think beyond the standard treatment strategy.

  1. Vitamin A and feeding statuses modulate the insulin-regulated gene expression in Zucker lean and fatty primary rat hepatocytes.

    Directory of Open Access Journals (Sweden)

    Wei Chen

    Full Text Available Unattended hepatic insulin resistance predisposes individuals to dyslipidemia, type 2 diabetes and many other metabolic complications. The mechanism of hepatic insulin resistance at the gene expression level remains unrevealed. To examine the effects of vitamin A (VA, total energy intake and feeding conditions on the insulin-regulated gene expression in primary hepatocytes of Zucker lean (ZL and fatty (ZF rats, we analyze the expression levels of hepatic model genes in response to the treatments of insulin and retinoic acid (RA. We report that the insulin- and RA-regulated glucokinase, sterol regulatory element-binding protein-1c and cytosolic form of phosphoenolpyruvate carboxykinase expressions are impaired in hepatocytes of ZF rats fed chow or a VA sufficient (VAS diet ad libitum. The impairments are partially corrected when ZF rats are fed a VA deficient (VAD diet ad libitum or pair-fed a VAS diet to the intake of their VAD counterparts in non-fasting conditions. Interestingly in the pair-fed ZL and ZF rats, transient overeating on the last day of pair-feeding regimen changes the expression levels of some VA catabolic genes, and impairs the insulin- and RA-regulated gene expression in hepatocytes. These results demonstrate that VA and feeding statuses modulate the hepatic insulin sensitivity at the gene expression level.

  2. Glucosensing capacity in rainbow trout liver displays day-night variations possibly related to melatonin action.

    Science.gov (United States)

    Conde-Sieira, Marta; Patiño, Marcos A López; Míguez, Jesús M; Soengas, José L

    2012-09-01

    To assess whether the glucosensing capacity in peripheral (liver and Brockmann bodies) and central (hypothalamus and hindbrain) locations of rainbow trout displays day-night variations in its response to changes in circulating glucose levels, we evaluated the response of parameters related to glucosensing [glucose, glycogen and glucose 6-phosphate levels, activities of glucokinase (GK), glycogen synthetase (GSase) and pyruvate kinase (PK), and mRNA abundance of GK, glucose transporter 2 (GLUT2), and K(ATP) channel subunits Kir6.x-like and sulfonylurea receptor (SUR)-like] in fish subjected to hyperglycemic treatment under night or day conditions. No day-night significant variations were noticed in the glucosensing capacity of the hypothalamus, hindbrain and Brockmann bodies. In contrast, a clear differential response was noticed in the liver, where glucose levels, GK activity (and mRNA levels) and GSase activity displayed increased values during the day in hyperglycemic fish compared with controls, and lower (GK mRNA levels) or non-existent (glucose, GK and GSase activities, and Kir6.x-like mRNA levels) values during the night. A similar decrease in parameters related to glucosensing in the liver was observed when fish under day conditions were treated with melatonin, suggesting a modulatory role of melatonin in day-night changes of the glucosensing response in the same tissue.

  3. Glucagon-Like Peptide-1 Secreting Cell Function as well as Production of Inflammatory Reactive Oxygen Species Is Differently Regulated by Glycated Serum and High Levels of Glucose

    Directory of Open Access Journals (Sweden)

    Alessandra Puddu

    2014-01-01

    Full Text Available Glucagon-like peptide-1 (GLP-1, an intestinal hormone contributing to glucose homeostasis, is synthesized by proglucagon and secreted from intestinal neuroendocrine cells in response to nutrients. GLP-1 secretion is impaired in type 2 diabetes patients. Here, we aimed at investigating whether diabetic toxic products (glycated serum (GS or high levels of glucose (HG may affect viability, function, and insulin sensitivity of the GLP-1 secreting cell line GLUTag. Cells were cultured for 5 days in presence or absence of different dilutions of GS or HG. GS and HG (alone or in combination increased reactive oxygen species (ROS production and upregulated proglucagon mRNA expression as compared to control medium. Only HG increased total production and release of active GLP-1, while GS alone abrogated secretion of active GLP-1. HG-mediated effects were associated with the increased cell content of the prohormone convertase 1/3 (PC 1/3, while GS alone downregulated this enzyme. HG upregulated Glucokinase (GK and downregulated SYNTHAXIN-1. GS abrogated SYNTHAXIN-1 and SNAP-25. Finally, high doses of GS alone or in combination with HG reduced insulin-mediated IRS-1 phosphorylation. In conclusion, we showed that GS and HG might regulate different pathways of GLP-1 production in diabetes, directly altering the function of neuroendocrine cells secreting this hormone.

  4. Antidiabetic Effect of an Active Components Group from Ilex kudingcha and Its Chemical Composition

    Directory of Open Access Journals (Sweden)

    Chengwu Song

    2012-01-01

    Full Text Available The leaves of Ilex kudingcha are used as an ethnomedicine in the treatment of symptoms related with diabetes mellitus and obesity throughout the centuries in China. The present study investigated the antidiabetic activities of an active components group (ACG obtained from Ilex kudingcha in alloxan-induced type 2 diabetic mice. ACG significantly reduced the elevated levels of serum glycaemic and lipids in type 2 diabetic mice. 3-Hydroxy-3-methylglutaryl coenzyme A reductase and glucokinase were upregulated significantly, while fatty acid synthetase, glucose-6-phosphatase catalytic enzyme was downregulated in diabetic mice after treatment of ACG. These findings clearly provided evidences regarding the antidiabetic potentials of ACG from Ilex kudingcha. Using LC-DAD/HR-ESI-TOF-MS, six major components were identified in ACG. They are three dicaffeoylquinic acids that have been reported previously, and three new triterpenoid saponins, which were the first time to be identified in Ilex kudingcha. It is reasonable to assume that antidiabetic activity of Ilex kudingcha against hyperglycemia resulted from these six major components. Also, synergistic effects among their compounds may exist in the antidiabetic activity of Ilex kudingcha.

  5. Type 2 Diabetic Rats on Diet Supplemented With Chromium Malate Show Improved Glycometabolism, Glycometabolism-Related Enzyme Levels and Lipid Metabolism

    Science.gov (United States)

    Feng, Weiwei; Zhao, Ting; Mao, Guanghua; Wang, Wei; Feng, Yun; Li, Fang; Zheng, Daheng; Wu, Huiyu; Jin, Dun; Yang, Liuqing; Wu, Xiangyang

    2015-01-01

    Our previous study showed that chromium malate improved the regulation of blood glucose in mice with alloxan-induced diabetes. The present study was designed to evaluate the effect of chromium malate on glycometabolism, glycometabolism-related enzymes and lipid metabolism in type 2 diabetic rats. Our results showed that fasting blood glucose, serum insulin level, insulin resistance index and C-peptide level in the high dose group had a significant downward trend when compared with the model group, chromium picolinate group and chromium trichloride group. The hepatic glycogen, glucose-6-phosphate dehydrogenase, glucokinase, Glut4, phosphor-AMPKβ1 and Akt levels in the high dose group were significantly higher than those of the model, chromium picolinate and chromium trichloride groups. Chromium malate in a high dose group can significantly increase high density lipoprotein cholesterol level while decreasing the total cholesterol, low density lipoprotein cholesterol and triglyceride levels when compared with chromium picolinate and chromium trichloride. The serum chromium content in chromium malate and chromium picolinate group is significantly higher than that of the chromium trichloride group. The results indicated that the curative effects of chromium malate on glycometabolism, glycometabolism-related enzymes and lipid metabolism changes are better than those of chromium picolinate and chromium trichloride. Chromium malate contributes to glucose uptake and transport in order to improved glycometabolism and glycometabolism-related enzymes. PMID:25942313

  6. Anti-diabetic effects of pumpkin and its components, trigonelline and nicotinic acid, on Goto-Kakizaki rats.

    Science.gov (United States)

    Yoshinari, Orie; Sato, Hideyo; Igarashi, Kiharu

    2009-05-01

    The effects of a pumpkin paste concentrate and its components on oral glucose tolerance and serum lipid levels were determined in non-obese type 2 diabetic Goto-Kakizaki (GK) rats. In the oral glucose tolerance test, the pumpkin paste concentrate-fed group maintained a lower glucose level than the control group between 15 and 60 min. The compounds considered to be effective in improving glucose tolerance and contained in the methanol extract of the pumpkin in relatively abundant amounts were isolated and identified as trigonelline (TRG) and nicotinic acid (NA).Feeding a diet containing TRG and NA respectively improved and tended to improve glucose tolerance. The insulin level increased after 15 min in the TRG-fed GK rats and then gradually decreased over the next 120 min. In contrast, a gradual increase was seen in the insulin level over 120 min in the control GK rats not fed with TRG, suggesting that TRG could improve the insulin resistance. The serum and liver triglyceride (TG) levels in the TRG- and NA-fed GK rats were lower than those in the control GK rats. Lower activity of liver fatty acid synthase (FAS), and higher activity of liver carnitine palmitoyl transferase (CPT) and glucokinase (GLK) in the TRG- and NA-fed GK rats than in the control GK rats were observed. This suggests that the regulation of these enzyme activities by TRG and NA was closely related to the suppression of both TG accumulation and the progression of diabetes.

  7. Deletion of hepatic FoxO1/3/4 genes in mice significantly impacts on glucose metabolism through downregulation of gluconeogenesis and upregulation of glycolysis.

    Directory of Open Access Journals (Sweden)

    Xiwen Xiong

    Full Text Available Forkhead transcription factors FoxO1/3/4 have pleiotrophic functions including anti-oxidative stress and metabolism. With regard to glucose metabolism, most studies have been focused on FoxO1. To further investigate their hepatic functions, we generated liver-specific FoxO1/3/4 knockout mice (LTKO and examined their collective impacts on glucose homeostasis under physiological and pathological conditions. As compared to wild-type mice, LTKO mice had lower blood glucose levels under both fasting and non-fasting conditions and they manifested better glucose and pyruvate tolerance on regular chow diet. After challenged by a high-fat diet, wild-type mice developed type 2 diabetes, but LTKO mice remained euglycemic and insulin-sensitive. To understand the underlying mechanisms, we examined the roles of SIRT6 (Sirtuin 6 and Gck (glucokinase in the FoxO-mediated glucose metabolism. Interestingly, ectopic expression of SIRT6 in the liver only reduced gluconeogenesis in wild-type but not LTKO mice whereas knockdown of Gck caused glucose intolerance in both wild-type and LTKO mice. The data suggest that both decreased gluconeogenesis and increased glycolysis may contribute to the overall glucose phenotype in the LTKO mice. Collectively, FoxO1/3/4 transcription factors play important roles in hepatic glucose homeostasis.

  8. Estimation of liver glucose metabolism after refeeding

    International Nuclear Information System (INIS)

    Rognstad, R.

    1987-01-01

    Refeeding or infusing glucose to rats fasted for 24 hr or more causes rapid liver glycogen synthesis, the carbon source now considered to be largely from gluconeogenesis. While substrate cycling between plasma glucose and liver glucose-6P is known to occur, this cycling has apparently been ignored when calculations are made of % contribution of direct and indirect pathways to liver glycogen synthesis, or when hepatic glucose output is calculated from glucose turnover minus the glucose infusion rate. They show that, isotopically, an estimate of the fluxes of liver glucokinase and glucose-6-phosphatase is required to quantitate sources of carbon for liver glycogen synthesis, and to measure hepatic glucose output (or uptake). They propose a method to estimate these fluxes, involving a short infusion of a 14 C labelled gluconeogenic precursor plus (6T)glucose, with determination of isotopic yields in liver glycogen and total glucose. Given also the rate of liver glycogen synthesis, this procedure permits the estimation of net gluconeogenesis and hepatic glucose output or uptake. Also, in vitro evidence against the notion of a drastic zonation of liver carbohydrate metabolism is presented, e.g. raising the glucose concentration from 10 to 25 mM increases the 14 C yield from H 14 CO 3 - in lactate, with the increased pyruvate kinase flux and decreased gluconeogenesis occurring in the same cell type, not opposing pathways in different hepatocyte types (as has been postulated by some to occur in vivo after refeeding

  9. Dexamethasone increases glucose cycling, but not glucose production, in healthy subjects

    International Nuclear Information System (INIS)

    Wajngot, A.; Khan, A.; Giacca, A.; Vranic, M.; Efendic, S.

    1990-01-01

    We established that measurement of glucose fluxes through glucose-6-phosphatase (G-6-Pase; hepatic total glucose output, HTGO), glucose cycling (GC), and glucose production (HGP), reveals early diabetogenic changes in liver metabolism. To elucidate the mechanism of the diabetogenic effect of glucocorticoids, we treated eight healthy subjects with oral dexamethasone (DEX; 15 mg over 48 h) and measured HTGO with [2-3H]glucose and HGP with [6-3H]glucose postabsorptively and during a 2-h glucose infusion (11.1 mumol.kg-1.min-1). [2-3H]- minus [6-3H]glucose equals GC. DEX significantly increased plasma glucose, insulin, C peptide, and HTGO, while HGP was unchanged. In controls and DEX, glucose infusion suppressed HTGO (82 vs. 78%) and HGP (87 vs. 91%). DEX increased GC postabsorptively (three-fold) P less than 0.005 and during glucose infusion (P less than 0.05) but decreased metabolic clearance and glucose uptake (Rd), which eventually normalized, however. Because DEX increased HTGO (G-6-Pase) and not HGP (glycogenolysis + gluconeogenesis), we assume that DEX increases HTGO and GC in humans by activating G-6-Pase directly, rather than by expanding the glucose 6-phosphate pool. Hyperglycemia caused by peripheral effects of DEX can also contribute to an increase in GC by activating glucokinase. Therefore, measurement of glucose fluxes through G-6-Pase and GC revealed significant early effects of DEX on hepatic glucose metabolism, which are not yet reflected in HGP

  10. Regulation of galactokinase gene expression in Tetrahymena thermophila. II. Identification of 3,4-dihydroxyphenylalanine as a primary effector of adrenergic control of galactokinase expression.

    Science.gov (United States)

    Ness, J C; Morse, D E

    1985-08-25

    Intracellular concentrations of catecholamines were determined in wild-type and mutant Tetrahymena thermophila, using the highly sensitive techniques of high-performance liquid chromatography and electro-chemical detection. Catecholamines were determined in these cell strains grown under various steady-state conditions, including those which initiate and maintain repression of galactokinase gene expression. Wild-type cells grown in defined minimal medium supplemented with 1% glycerol, exhibiting derepressed galactokinase synthesis, were found to contain considerable quantities of dopa (3,4-dihydroxyphenylalanine) and dopamine, but no detectable levels of either norepinephrine or epinephrine. Analyses of wild-type cells revealed a strong positive correlation between the internal concentration of dopa and expression of the galactokinase gene, both of which are regulated by exogenous carbohydrates, catecholamine agonists, or dibutyryl-cAMP; an analogous relationship between intracellular dopamine concentrations and galactokinase activity was not found. In addition, a correlation between intracellular dopa content and the phenotypic expression of galactokinase in various mutants deficient in the catecholamine biosynthetic pathway or in glucokinase further confirms the role of dopa as a primary effector in the regulation of galactokinase gene expression.

  11. Pharmacological and Morphological Evidence of AMPK-Mediated Energy Sensing in the Lower Brain Stem Ependymocytes to Control Reproduction in Female Rodents.

    Science.gov (United States)

    Minabe, Shiori; Deura, Chikaya; Ikegami, Kana; Goto, Teppei; Sanbo, Makoto; Hirabayashi, Masumi; Inoue, Naoko; Uenoyama, Yoshihisa; Maeda, Kei-Ichiro; Tsukamura, Hiroko

    2015-06-01

    Ependymocytes are one of the energy-sensing cells that regulate animal reproduction through their responsiveness to changes in extracellular glucose levels and the expression of pancreatic-type glucokinase and glucose transporter 2, which play a critical role in sensing blood glucose levels in pancreatic β-cells. Molecular mechanisms underlying glucose sensing in the ependymocytes remain poorly understood. The AMP-activated protein kinase (AMPK), a serine/threonine kinase highly conserved in all eukaryotic cells, has been suggested to be an intracellular fuel gauge that detects cellular energy status. The present study aims to clarify the role AMPK of the lower brainstem ependymocytes has in sensing glucose levels to regulate reproductive functions. First, we will show that administration of 5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside, an AMPK activator, into the 4th ventricle suppressed pulsatile LH release in female rats. Second, we will demonstrate the presence of AMPK catalytic subunit immunoreactivities in the rat lower brainstem ependymocytes. Third, transgenic mice were generated to visualize the ependymocytes with Venus, a green fluorescent protein, expressed under the control of the mouse vimentin promoter for further in vitro study. The Venus-labeled ependymocytes taken from the lower brainstem of transgenic mice revealed that AMPK activation by 5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside, an AMPK activator, increased in vitro intracellular calcium concentrations. Taken together, malnutrition-induced AMPK activation of ependymocytes of the lower brainstem might be involved in suppression of GnRH/LH release and then gonadal activities.

  12. Hypoglycemic, hepatoprotective and molecular docking studies of 5-[(4-chlorophenoxy methyl]-1, 3, 4-oxadiazole-2-thiol

    Directory of Open Access Journals (Sweden)

    Naureen Shehzadi

    2018-05-01

    Full Text Available The present study aimed at the evaluation of anti-hyperglycemic and hepatoprotective potential of a new drug candidate, 5-[(4-chlorophenoxy methyl]-1,3,4-oxadiazole-2-thiol (OXCPM through in vitro and in vivo assays, respectively. The compound displayed excellent dose-dependent ɑ-amylase (28.0-92.0%, ɑ-glucosidase (40.3-93.1% and hemoglobin glycosylation (9.0%-54.9% inhibitory effects and promoted the uptake of glucose by the yeast cells (0.2 to 26.3%. The treatment of the isoniazid- and rifampicin- (p.o., 50 mg/kg of each intoxicated rats with OXCPM (100 mg/kg, p.o. resulted in restoring the normal serum levels of the non-enzymatic (total bilirubin, total protein and albumin and bringing about a remarkable decrease in the levels of enzymatic (alanine transaminases, aspartate transaminases and alkaline phosphatase biomarkers. The molecular docking studies indicated high binding affinity of the compound for hyperglycemia-related protein targets; fructose-1,6-bisphosphatase, beta2-adrenergic receptors and glucokinase. The results indicate that OXCPM may not only reduce hyperglycemia by enzyme inhibition but also the disease complications through protection of hemoglobin glycosylation and hepatic injury.

  13. Antidiabetic effects of Artemisia sphaerocephala Krasch. gum, a novel food additive in China, on streptozotocin-induced type 2 diabetic rats.

    Science.gov (United States)

    Xing, Xiao-Hui; Zhang, Zheng-Mao; Hu, Xin-Zhong; Wu, Rui-Qin; Xu, Chao

    2009-09-25

    Since ancient times, practicians of traditional Chinese medicine have discovered that Artemisia sphaerocephala Krasch. (Asteraceae) seed powder was useful for the treatment of diabetes. Artemisia sphaerocephala Krasch. gum (ASK gum), which is extracted from seed powder of the plant, is a novel food additive favored by the food industry in China. The objective of this study was to determine the antidiabetic function of ASK gum on type 2 diabetes. Type 2 diabetic rat model was induced with high fat diet and low dose of streptozotocin (STZ). The effects of ASK gum on hyperglycemia, hyperlipemia, insulin resistance, and liver fat accumulation in type 2 diabetic rats were evaluated. The results were compared to those of normal rats and diabetic rats treated with metformin. The addition of ASK gum to the rats' food supply significantly lowered fasting blood glucose, glycated serum protein, serum cholesterol, and serum triglyceride in type 2 diabetic rats, and significantly elevated liver glucokinase, liver glycogen, and serum high density protein cholesterol in the diabetic rats. ASK gum significantly reduced insulin resistance and liver fat accumulation of type 2 diabetes. Artemisia sphaerocephala Krasch. gum can alleviate hyperglycemia, hyperlipemia and insulin resistance of type 2 diabetes.

  14. Profiling Gene Expression in Germinating Brassica Roots.

    Science.gov (United States)

    Park, Myoung Ryoul; Wang, Yi-Hong; Hasenstein, Karl H

    2014-01-01

    Based on previously developed solid-phase gene extraction (SPGE) we examined the mRNA profile in primary roots of Brassica rapa seedlings for highly expressed genes like ACT7 (actin7), TUB (tubulin1), UBQ (ubiquitin), and low expressed GLK (glucokinase) during the first day post-germination. The assessment was based on the mRNA load of the SPGE probe of about 2.1 ng. The number of copies of the investigated genes changed spatially along the length of primary roots. The expression level of all genes differed significantly at each sample position. Among the examined genes ACT7 expression was most even along the root. UBQ was highest at the tip and root-shoot junction (RS). TUB and GLK showed a basipetal gradient. The temporal expression of UBQ was highest in the MZ 9 h after primary root emergence and higher than at any other sample position. Expressions of GLK in EZ and RS increased gradually over time. SPGE extraction is the result of oligo-dT and oligo-dA hybridization and the results illustrate that SPGE can be used for gene expression profiling at high spatial and temporal resolution. SPGE needles can be used within two weeks when stored at 4 °C. Our data indicate that gene expression studies that are based on the entire root miss important differences in gene expression that SPGE is able to resolve for example growth adjustments during gravitropism.

  15. Genomic analysis reveals versatile heterotrophic capacity of a potentially symbiotic sulfur-oxidizing bacterium in sponge

    KAUST Repository

    Tian, Renmao

    2014-08-29

    Sulfur-reducing bacteria (SRB) and sulfur-oxidizing bacteria (SOB) play essential roles in marine sponges. However, the detailed characteristics and physiology of the bacteria are largely unknown. Here, we present and analyse the first genome of sponge-associated SOB using a recently developed metagenomic binning strategy. The loss of transposase and virulence-associated genes and the maintenance of the ancient polyphosphate glucokinase gene suggested a stabilized SOB genome that might have coevolved with the ancient host during establishment of their association. Exclusive distribution in sponge, bacterial detoxification for the host (sulfide oxidation) and the enrichment for symbiotic characteristics (genes-encoding ankyrin) in the SOB genome supported the bacterial role as an intercellular symbiont. Despite possessing complete autotrophic sulfur oxidation pathways, the bacterium developed a much more versatile capacity for carbohydrate uptake and metabolism, in comparison with its closest relatives (Thioalkalivibrio) and to other representative autotrophs from the same order (Chromatiales). The ability to perform both autotrophic and heterotrophic metabolism likely results from the unstable supply of reduced sulfur in the sponge and is considered critical for the sponge-SOB consortium. Our study provides insights into SOB of sponge-specific clade with thioautotrophic and versatile heterotrophic metabolism relevant to its roles in the micro-environment of the sponge body. © 2014 Society for Applied Microbiology and John Wiley & Sons Ltd.

  16. In Vivo Hypoglycaemic Effect and Inhibitory Mechanism of the Branch Bark Extract of the Mulberry on STZ-Induced Diabetic Mice

    Directory of Open Access Journals (Sweden)

    Hua-Yu Liu

    2014-01-01

    Full Text Available Branch bark extract (BBE derived from the mulberry cultivar Husang 32 (Morus multicaulis L. with aqueous alcohol solution has been investigated as an inhibitor of α-glycosidase in vitro. Mulberry BBE was orally administered to STZ-induced diabetic mice for three weeks, and it improved the weight gain and ameliorated the swelling of liver and kidney in diabetic mice. Obviously, mulberry BBE not only can reduce the abnormally elevated levels of serum insulin and ameliorate insulin resistance induced by STZ, but also it regulates dyslipidemia in diabetic mice. To understand this therapeutic effect and the regulatory mechanisms of BBE in diabetic mice, a qRT-PCR experiment was performed, indicating that the mulberry BBE can regulate the mRNA expression of glycometabolism genes in diabetic mice, including glucose-6-phosphatase (G6Pase, glucokinase (GCK, and phosphoenolpyruvate carboxykinase (PEPCK, thereby regulating sugar metabolism and reducing the blood glucose level in diabetic mice. The mulberry BBE can increase the mRNA expression of the genes Ins1, Ins2 and pancreatic duodenal homeobox-1 (PDX-1 and may decrease the insulin resistance in diabetic mice. Those results provide an important basis for making the best use of mulberry branch resources and producing biomedical drugs with added value.

  17. Dietary Variation and Evolution of Gene Copy Number among Dog Breeds.

    Directory of Open Access Journals (Sweden)

    Taylor Reiter

    Full Text Available Prolonged human interactions and artificial selection have influenced the genotypic and phenotypic diversity among dog breeds. Because humans and dogs occupy diverse habitats, ecological contexts have likely contributed to breed-specific positive selection. Prior to the advent of modern dog-feeding practices, there was likely substantial variation in dietary landscapes among disparate dog breeds. As such, we investigated one type of genetic variant, copy number variation, in three metabolic genes: glucokinase regulatory protein (GCKR, phytanol-CoA 2-hydroxylase (PHYH, and pancreatic α-amylase 2B (AMY2B. These genes code for proteins that are responsible for metabolizing dietary products that originate from distinctly different food types: sugar, meat, and starch, respectively. After surveying copy number variation among dogs with diverse dietary histories, we found no correlation between diet and positive selection in either GCKR or PHYH. Although it has been previously demonstrated that dogs experienced a copy number increase in AMY2B relative to wolves during or after the dog domestication process, we demonstrate that positive selection continued to act on amylase copy number in dog breeds that consumed starch-rich diets in time periods after domestication. Furthermore, we found that introgression with wolves is not responsible for deterioration of positive selection on AMY2B among diverse dog breeds. Together, this supports the hypothesis that the amylase copy number expansion is found universally in dogs.

  18. Advanced water splitting for green hydrogen gas production through complete oxidation of starch by in vitro metabolic engineering.

    Science.gov (United States)

    Kim, Jae-Eung; Kim, Eui-Jin; Chen, Hui; Wu, Chang-Hao; Adams, Michael W W; Zhang, Y-H Percival

    2017-11-01

    Starch is a natural energy storage compound and is hypothesized to be a high-energy density chemical compound or solar fuel. In contrast to industrial hydrolysis of starch to glucose, an alternative ATP-free phosphorylation of starch was designed to generate cost-effective glucose 6-phosphate by using five thermophilic enzymes (i.e., isoamylase, alpha-glucan phosphorylase, 4-α-glucanotransferase, phosphoglucomutase, and polyphosphate glucokinase). This enzymatic phosphorolysis is energetically advantageous because the energy of α-1,4-glycosidic bonds among anhydroglucose units is conserved in the form of phosphorylated glucose. Furthermore, we demonstrated an in vitro 17-thermophilic enzyme pathway that can convert all glucose units of starch, regardless of branched and linear contents, with water to hydrogen at a theoretic yield (i.e., 12 H 2 per glucose), three times of the theoretical yield from dark microbial fermentation. The use of a biomimetic electron transport chain enabled to achieve a maximum volumetric productivity of 90.2mmol of H 2 /L/h at 20g/L starch. The complete oxidation of starch to hydrogen by this in vitro synthetic (enzymatic) biosystem suggests that starch as a natural solar fuel becomes a high-density hydrogen storage compound with a gravimetric density of more than 14% H 2 -based mass and an electricity density of more than 3000Wh/kg of starch. Copyright © 2017. Published by Elsevier Inc.

  19. Oat beta-glucan ameliorates insulin resistance in mice fed on high-fat and high-fructose diet

    Directory of Open Access Journals (Sweden)

    Jie Zheng

    2013-12-01

    Full Text Available Methods: This study sought to evaluate the impact of oat beta-glucan on insulin resistance in mice fed on high-fat and high-fructose diet with fructose (10%, w/v added in drinking water for 10 weeks. Results: The results showed that supplementation with oat beta-glucan could significantly reduce the insulin resistance both in low-dose (200 mg/kg−1 body weight and high-dose (500 mg/kg−1 body weight groups, but the high-dose group showed a more significant improvement in insulin resistance (P<0.01 compared with model control (MC group along with significant improvement in hepatic glycogen level, oral glucose, and insulin tolerance. Moreover, hepatic glucokinase activity was markedly enhanced both in low-dose and high-dose groups compared with that of MC group (P<0.05. Conclusion: These results suggested that supplementation of oat beta-glucan alleviated insulin resistance and the effect was dose dependent.

  20. A De Novo Whole GCK Gene Deletion Not Detected by Gene Sequencing, in a Boy with Phenotypic GCK Insufficiency

    Directory of Open Access Journals (Sweden)

    N. H. Birkebæk

    2011-01-01

    Full Text Available We report on a boy with diabetes mellitus and a phenotype indicating glucokinase (GCK insufficiency, but a normal GCK gene examination applying direct gene sequencing. The boy was referred for diabetes mellitus at 7.5 years old. His father, grandfather and great grandfather suffered type 2 DM. Several blood glucose profiles showed (BG of 6.5–10 mmol/L L. After three years on neutral insulin Hagedorn (NPH in a dose of 0.3 IU/kg/day haemoglobin A1c (HbA1c was 6.8%. Treatment was changed to sulphonylurea 750 mg a day, and after 4 years HbA1c was 7%. At that time a multiplex ligation-dependent amplification gene dosage assay (MLPA was done, revealing a whole GCK gene deletion. Medical treatment was ceased, and after one year HbA1c was 6.8%. This case underscores the importance of a MLPA examination if the phenotype of a patient is strongly indicative of GCK insufficiency and no mutation is identified using direct sequencing.

  1. Reducing properties, energy efficiency and carbohydrate metabolism in hyperhydric and normal carnation shoots cultured in vitro: a hypoxia stress?

    Science.gov (United States)

    Saher, Shady; Fernández-García, Nieves; Piqueras, Abel; Hellín, Eladio; Olmos, Enrique

    2005-06-01

    Hyperhydricity is considered as a physiological disorder that can be induced by different stressing conditions. In the present work we have studied the metabolic and energetic states of hyperhydric carnation shoots. We have evaluated the hypothesis that hypoxia stress is the main factor affecting the metabolism of hyperhydric leaves. Our results indicate a low level of ATP in hyperhydric tissues, but only slight modifications in pyridine nucleotide contents. Concurrently, the glucose-6-phosphate dehydrogenase (G-6-PDH; EC 1.1.1.49) activity in hyperhydric leaves was increased but glucokinase (GK; EC 2.7.1.2) activity was unchanged. We have observed that the metabolism of pyruvate was altered in hyperhydric tissues by the induction of pyruvate synthesis via NADP-dependent malic enzyme (EC 1.1.1.40). The enzymes of the fermentative metabolism pyruvate decarboxylase (PDC; EC 4.1.1.1) and alcohol dehydrogenase (ADH; EC 1.1.1.1) were highly increased in hyperhydric leaves. Sucrose metabolism was modified in hyperhydric leaves with a high increase in the activity of both synthesis and catabolic enzymes. The analysis of the sucrose, glucose and fructose contents indicated that all of these sugars were accumulated in hyperhydric leaves. However, the pinitol content was drastically decreased in hyperhydric leaves. We consider that these results suggest that hyperhydric leaves of carnation have adapted to hypoxia stress conditions by the induction of the oxidative pentose phosphate and fermentative pathways.

  2. Pharmacological effects of biotin.

    Science.gov (United States)

    Fernandez-Mejia, Cristina

    2005-07-01

    In the last few decades, more vitamin-mediated effects have been discovered at the level of gene expression. Increasing knowledge on the molecular mechanisms of these vitamins has opened new perspectives that form a connection between nutritional signals and the development of new therapeutic agents. Besides its role as a carboxylase prosthetic group, biotin regulates gene expression and has a wide repertoire of effects on systemic processes. The vitamin regulates genes that are critical in the regulation of intermediary metabolism: Biotin has stimulatory effects on genes whose action favors hypoglycemia (insulin, insulin receptor, pancreatic and hepatic glucokinase); on the contrary, biotin decreases the expression of hepatic phosphoenolpyruvate carboxykinase, a key gluconeogenic enzyme that stimulates glucose production by the liver. The findings that biotin regulates the expression of genes that are critical in the regulation of intermediary metabolism are in agreement with several observations that indicate that biotin supply is involved in glucose and lipid homeostasis. Biotin deficiency has been linked to impaired glucose tolerance and decreased utilization of glucose. On the other hand, the diabetic state appears to be ameliorated by pharmacological doses of biotin. Likewise, pharmacological doses of biotin appear to decrease plasma lipid concentrations and modify lipid metabolism. The effects of biotin on carbohydrate metabolism and the lack of toxic effects of the vitamin at pharmacological doses suggest that biotin could be used in the development of new therapeutics in the treatment of hyperglycemia and hyperlipidemia, an area that we are actively investigating.

  3. [Discovery of the target genes inhibited by formic acid in Candida shehatae].

    Science.gov (United States)

    Cai, Peng; Xiong, Xujie; Xu, Yong; Yong, Qiang; Zhu, Junjun; Shiyuan, Yu

    2014-01-04

    At transcriptional level, the inhibitory effects of formic acid was investigated on Candida shehatae, a model yeast strain capable of fermenting xylose to ethanol. Thereby, the target genes were regulated by formic acid and the transcript profiles were discovered. On the basis of the transcriptome data of C. shehatae metabolizing glucose and xylose, the genes responsible for ethanol fermentation were chosen as candidates by the combined method of yeast metabolic pathway analysis and manual gene BLAST search. These candidates were then quantitatively detected by RQ-PCR technique to find the regulating genes under gradient doses of formic acid. By quantitative analysis of 42 candidate genes, we finally identified 10 and 5 genes as markedly down-regulated and up-regulated targets by formic acid, respectively. With regard to gene transcripts regulated by formic acid in C. shehatae, the markedly down-regulated genes ranking declines as follows: xylitol dehydrogenase (XYL2), acetyl-CoA synthetase (ACS), ribose-5-phosphate isomerase (RKI), transaldolase (TAL), phosphogluconate dehydrogenase (GND1), transketolase (TKL), glucose-6-phosphate dehydrogenase (ZWF1), xylose reductase (XYL1), pyruvate dehydrogenase (PDH) and pyruvate decarboxylase (PDC); and a declining rank for up-regulated gens as follows: fructose-bisphosphate aldolase (ALD), glucokinase (GLK), malate dehydrogenase (MDH), 6-phosphofructokinase (PFK) and alcohol dehydrogenase (ADH).

  4. Glycolysis and gluconeogenesis in the liver of catfish fed with different concentrations of proteins, lipids and carbohydrates

    Directory of Open Access Journals (Sweden)

    J.F.B. Melo

    Full Text Available ABSTRACT The activities of enzymes from a number of metabolic pathways have been used as a tool to evaluate the best use of nutrients on fish performance. In the present study the catfish Rhamdia quelen was fed with diets containing crude protein-lipid-carbohydrate (% as follows: treatment (T T1: 19-19-44; T2: 26-15-39; T3: 33-12-33; and T4: 40-10-24. The fish were held in tanks of re-circulated, filtered water with controlled temperature and aeration in 2000L experimental units. The feeding experiment lasted 30 days. The following enzymes of the carbohydrate metabolism were determined: Glucokinase (GK, Phosphofructokinase 1 (PFK-1, Pyruvate kinase (PK, Fructose-1,6-biphosphatase 1 (FBP-1. The activities of 6 phosphogluconate dehydrogenase (6PGDH and glucose 6 phosphate dehydrogenase (G6PDH were also assayed. The influence of nutrient levels on the enzyme activities is reported. The increase of dietary protein plus reduction of carbohydrates and lipids attenuates the glycolytic activity and induces hepatic gluconeogenesis as a strategy to provide metabolic energy from amino acids. The fish performance was affected by the concentrations of protein, lipid and carbohydrates in the diet. The greatest weight gain was obtained in fish fed diet T4 containing 40.14% of crude protein, 9.70% of lipids, and 24.37% of carbohydrate, respectively.

  5. Time-dependent changes in the contribution of gluconeogenic precursors and glucose to glycogenesis in isolated rate hepatocytes

    International Nuclear Information System (INIS)

    Marden, L.J.; Davidson, A.L.; Arion, W.J.

    1986-01-01

    Hepatocytes from 21-hr fasted rats were incubated for up to 60 min with 10 mM glucose and gluconeogeneic precursors: 4 mM lactate/0.4 mM pyruvate plus 5 mM alanine and 2 mM fructose or 10 mM glutamine. Tracer 3- 3 H,U- 14 C-glucose was added 15 min before terminating the incubations. In all cases, the 3 H and 14 C specific activities of the newly synthesized glycogen increased over time, relative to the specific activities of medium glucose. The percentage of new carbon in glycogen originating from glucose increased from less than 50% in the first 15 min to over 85% after 30 min. Relative to medium glucose, the ratio of 3 H: 14 C in glycogen was about 0.9 through-out the incubations, indicating direct incorporation of glucose into glycogen without significant prior transformation via the pentose pathway or recycling to triose phosphates. Insulin did not stimulate glucose incorporation into glycogen. 3-Mercaptopicolinate decreased the incorporation of precursor carbon into glycogen during incubations with glutamine but not during incubations with fructose and alanine. These data indicate time-dependent and reciprocal changes in rates of glucose-6-P synthesis from gluconeogenic precursors and glucose. Activation of glucokinase may underlie the increased contribution of glucose to glycogenesis. Thus, the relative importance of glucose and gluconeogenic precursors as substrates for glycogenesis directly reflects their respective contributions to the cellular pool of the glucose-6-P

  6. Glucose and hypothalamic astrocytes: More than a fueling role?

    Science.gov (United States)

    Leloup, C; Allard, C; Carneiro, L; Fioramonti, X; Collins, S; Pénicaud, L

    2016-05-26

    Brain plays a central role in energy homeostasis continuously integrating numerous peripheral signals such as circulating nutrients, and in particular blood glucose level, a variable that must be highly regulated. Then, the brain orchestrates adaptive responses to modulate food intake and peripheral organs activity in order to achieve the fine tuning of glycemia. More than fifty years ago, the presence of glucose-sensitive neurons was discovered in the hypothalamus, but what makes them specific and identifiable still remains disconnected from their electrophysiological signature. On the other hand, astrocytes represent the major class of macroglial cells and are now recognized to support an increasing number of neuronal functions. One of these functions consists in the regulation of energy homeostasis through neuronal fueling and nutrient sensing. Twenty years ago, we discovered that the glucose transporter GLUT2, the canonical "glucosensor" of the pancreatic beta-cell together with the glucokinase, was also present in astrocytes and participated in hypothalamic glucose sensing. Since then, many studies have identified other actors and emphasized the astroglial participation in this mechanism. Growing evidence suggest that astrocytes form a complex network and have to be considered as spatially coordinated and regulated metabolic units. In this review we aim to provide an updated view of the molecular and respective cellular pathways involved in hypothalamic glucose sensing, and their relevance in physiological and pathological states. Copyright © 2015 IBRO. Published by Elsevier Ltd. All rights reserved.

  7. Hypothalamic pathogenesis of type 2 diabetes.

    Science.gov (United States)

    Koshiyama, Hiroyuki; Hamamoto, Yoshiyuki; Honjo, Sachiko; Wada, Yoshiharu; Lkeda, Hiroki

    2006-01-01

    There have recently been increasing experimental and clinical evidences suggesting that hypothalamic dysregulation may be one of the underlying mechanisms of abnormal glucose metabolism. First, increased hypothalamic-pituitary-adrenal axis activity induced by uncontrollable excess stress may cause diabetes mellitus as well as dyslipidemia, visceral obesity, and osteoporosis with some resemblance to Cushing's disease. Second, several molecules are known to be expressed both in pancreas and hypothalamus; adenosine triphosphate-sensitive potassium channels, malonyl-CoA, glucokinase, and AMP-activated protein kinase. Those molecules appear to form an integrated hypothalamic system, which may sense hypothalamic fuel status, especially glucose level, and inhibit action of insulin on hepatic gluconeogenesis, thereby forming a brain-liver circuit. Third, hypothalamic resistance to insulin as an adiposity signal may be involved in pathogenesis of peripheral insulin resistance. The results with mice with a neuron-specific disruption of the insulin receptor gene or those lacking insulin receptor substrate 2 in hypothalamus supported this possibility. Finally, it has very recently been suggested that dysregulation of clock genes in hypothalamus may cause abnormal glucose metabolism. Taken together, it is plausible that some hypothalamic abnormality may underlie at least some portion of type 2 diabetes or insulin resistance in humans, and this viewpoint of hypothalamic pathogenesis of type 2 diabetes may lead to the development of new drugs for type 2 diabetes.

  8. Monogenic hyperinsulinemic hypoglycemia: current insights into the pathogenesis and management

    Directory of Open Access Journals (Sweden)

    Lord Katherine

    2013-02-01

    Full Text Available Abstract Hyperinsulinism (HI is the leading cause of persistent hypoglycemia in children, which if unrecognized may lead to development delays and permanent neurologic damage. Prompt recognition and appropriate treatment of HI are essential to avoid these sequelae. Major advances have been made over the past two decades in understanding the molecular basis of hyperinsulinism and mutations in nine genes are currently known to cause HI. Inactivating KATP channel mutations cause the most common and severe type of HI, which occurs in both a focal and a diffuse form. Activating mutations of glutamate dehydrogenase (GDH lead to hyperinsulinism/hyperammonemia syndrome, while activating mutations of glucokinase (GK, the “glucose sensor” of the beta cell, causes hyperinsulinism with a variable clinical phenotype. More recently identified genetic causes include mutations in the genes encoding short-chain 3-hydroxyacyl-CoA (SCHAD, uncoupling protein 2 (UCP2, hepatocyte nuclear factor 4-alpha (HNF-4α, hepatocyte nuclear factor 1-alpha (HNF-1α, and monocarboyxlate transporter 1 (MCT-1, which results in a very rare form of HI triggered by exercise. For a timely diagnosis, a critical sample and a glucagon stimulation test should be done when plasma glucose is ATP channel agonist, suggests a KATP defect, which frequently requires pancreatectomy. Surgery is palliative for children with diffuse KATPHI, but children with focal KATPHI are cured with a limited pancreatectomy. Therefore, distinguishing between diffuse and focal disease and localizing the focal lesion in the pancreas are crucial aspects of HI management. Since 2003, 18 F-DOPA PET scans have been used to differentiate diffuse and focal disease and localize focal lesions with higher sensitivity and specificity than more invasive interventional radiology techniques. Hyperinsulinism remains a challenging disorder, but recent advances in the understanding of its genetic basis and breakthroughs in

  9. Hypoglycaemia related to inherited metabolic diseases in adults

    Directory of Open Access Journals (Sweden)

    Douillard Claire

    2012-05-01

    Full Text Available Abstract In non-diabetic adult patients, hypoglycaemia may be related to drugs, critical illness, cortisol or glucagon insufficiency, non-islet cell tumour, insulinoma, or it may be surreptitious. Nevertheless, some hypoglycaemic episodes remain unexplained, and inborn errors of metabolism (IEM should be considered, particularly in cases of multisystemic involvement. In children, IEM are considered a differential diagnosis in cases of hypoglycaemia. In adulthood, IEM-related hypoglycaemia can persist in a previously diagnosed childhood disease. Hypoglycaemia may sometimes be a presenting sign of the IEM. Short stature, hepatomegaly, hypogonadism, dysmorphia or muscular symptoms are signs suggestive of IEM-related hypoglycaemia. In both adults and children, hypoglycaemia can be clinically classified according to its timing. Postprandial hypoglycaemia can be an indicator of either endogenous hyperinsulinism linked to non-insulinoma pancreatogenic hypoglycaemia syndrome (NIPHS, unknown incidence in adults or very rarely, inherited fructose intolerance. Glucokinase-activating mutations (one family are the only genetic disorder responsible for NIPH in adults that has been clearly identified so far. Exercise-induced hyperinsulinism is linked to an activating mutation of the monocarboxylate transporter 1 (one family. Fasting hypoglycaemia may be caused by IEM that were already diagnosed in childhood and persist into adulthood: glycogen storage disease (GSD type I, III, 0, VI and IX; glucose transporter 2 deficiency; fatty acid oxidation; ketogenesis disorders; and gluconeogenesis disorders. Fasting hypoglycaemia in adulthood can also be a rare presenting sign of an IEM, especially in GSD type III, fatty acid oxidation [medium-chain acyl-CoA dehydrogenase (MCAD, ketogenesis disorders (3-hydroxy-3-methyl-glutaryl-CoA (HMG-CoA lyase deficiency, and gluconeogenesis disorders (fructose-1,6-biphosphatase deficiency].

  10. Type 2 Diabetes Mellitus: A Review of Current Trends

    Directory of Open Access Journals (Sweden)

    Abdulfatai B. Olokoba

    2012-07-01

    Full Text Available Type 2 diabetes mellitus (DM is a chronic metabolic disorder in which prevalence has been increasing steadily all over the world. As a result of this trend, it is fast becoming an epidemic in some countries of the world with the number of people affected expected to double in the next decade due to increase in ageing population, thereby adding to the already existing burden for healthcare providers, especially in poorly developed countries. This review is based on a search of Medline, the Cochrane Database of Systemic Reviews, and citation lists of relevant publications. Subject heading and key words used include type 2 diabetes mellitus, prevalence, current diagnosis, and current treatment. Only articles in English were included. Screening and diagnosis is still based on World Health Organization (WHO and American Diabetes Association (ADA criteria which include both clinical and laboratory parameters. No cure has yet been found for the disease; however, treatment modalities include lifestyle modifications, treatment of obesity, oral hypoglycemic agents, and insulin sensitizers like metformin, a biguanide that reduces insulin resistance, is still the recommended first line medication especially for obese patients. Other effective medications include non-sulfonylurea secretagogues, thiazolidinediones, alpha glucosidase inhibitors, and insulin. Recent research into the pathophysiology of type 2 DM has led to the introduction of new medications like glucagon-like peptide 1 analogoues: dipeptidyl peptidase-IV inhibitors, inhibitors of the sodium-glucose cotransporter 2 and 11ß-hydroxysteroid dehydrogenase 1, insulin-releasing glucokinase activators and pancreatic-G-protein-coupled fatty-acid-receptor agonists, glucagon-receptor antagonists, metabolic inhibitors of hepatic glucose output and quick-release bromocriptine. Inhaled insulin was licensed for use in 2006 but has been withdrawn from the market because of low patronage.

  11. The ethyl acetate fraction of corn silk exhibits dual antioxidant and anti-glycation activities and protects insulin-secreting cells from glucotoxicity.

    Science.gov (United States)

    Chang, Chia-Chuan; Yuan, Wei; Roan, Hsiao-Yuh; Chang, Jia-Ling; Huang, Hsiu-Chen; Lee, Yu-Ching; Tsay, Huey Jen; Liu, Hui-Kang

    2016-11-03

    In this study, we aimed to develop a Stigmata Maydis (corn silk) fraction with dual bio-activities against oxidative stress and protein glycation to protect β-cells from diabetes-induced failure. Corn silk fractions were prepared by partition and chemically characterised by thin-layer chromatography. Free radical scavenging assay, glycation assay, and cell-based viability test (neutral red) were employed to decide the best fraction. Cell death analysis was executed by annexin V/ Propidium iodide staining. Cell proliferation was measured by WST-1. Finally, β-cell function was evaluated by β-cell marker gene expression (RT-PCR) and acute insulin secretion test. Four corn silk fractions were prepared from an ethanolic crude extract of corn silk. In vitro assays indicate ethyl acetate fraction (YMS-EA) was the most potent fraction. YMS-EA also attenuated the hydrogen peroxide- or methylglyoxal-induced induction of reactive oxygen species, reduction of cell viability, and inhibition of cell proliferation. However, YMS-EA was unable to prevent hydrogen peroxide-induced apoptosis or advanced glycation end-products-induced toxicity. Under hyperglycemic conditions, YMS-EA effectively reduced ROS levels, improved mRNA expression of insulin, glucokinase, and PDX-1, and enhanced glucose-stimulated insulin secretion. The similarity of bioactivities among apigenin, luteolin, and YMS-EA indicated that dual activities of YMS-EA might be derived from those compounds. We concluded that YMS-EA fraction could be developed as a preventive food agent against the glucotoxicity to β-cells in Type 2 diabetes.

  12. A three-step programmed method for the identification of causative gene mutations of maturity onset diabetes of the young (MODY).

    Science.gov (United States)

    Li, Qian; Cao, Xi; Qiu, Hai-Yan; Lu, Jing; Gao, Rui; Liu, Chao; Yuan, Ming-Xia; Yang, Guang-Ran; Yang, Jin-Kui

    2016-08-22

    To establish a three-step programmed method to find gene mutations related to maturity onset diabetes of the young (MODY). Target region capture and next-generation sequencing (NGS) were performed using customized oligonucleotide probes designed to capture suspected genes for MODY in 11 probands with clinically diagnosed MODY. The suspected associations of certain genes with MODY were then confirmed by Sanger sequencing in the probands and their family members. Finally, to validate variants of one of the genes of interest (glucokinase, GCK) as pathogenic mutations, protein function editing by the variant genes was assessed. In the target region capture and NGS phase, a total of nine variants of seven genes (GCK, WFS1, SLC19A2, SH2B1, SERPINB4, RFX6, and GATA6) were identified in eight probands. Two heterozygous GCK mutations located on the same allele (p.Leu77Arg and p.Val101Met) were identified in a MODY family. Sanger sequencing was used to confirm the variants identified by NGS to be present in probands and their diabetic family members, but not in non-diabetic family members. Finally, enzyme kinetic and thermal stability analyses revealed that the p.Leu77Arg mutation or the p.Leu77Arg mutation in combination with the p.Val101Met mutation inactivates GCK function and stability, while mutation of p.Val101Met alone does not. The p.Leu77Arg but not p.Val101Met GCK mutation is therefore considered a pathogenic mutation associated with MODY. Genetic screening coupled with gene-editing protein function testing is an effective and reliable method by which causative gene mutations of MODY can be identified. Copyright © 2016 Elsevier B.V. All rights reserved.

  13. GCK-MODY diabetes associated with protein misfolding, cellular self-association and degradation.

    Science.gov (United States)

    Negahdar, Maria; Aukrust, Ingvild; Johansson, Bente B; Molnes, Janne; Molven, Anders; Matschinsky, Franz M; Søvik, Oddmund; Kulkarni, Rohit N; Flatmark, Torgeir; Njølstad, Pål Rasmus; Bjørkhaug, Lise

    2012-11-01

    GCK-MODY, dominantly inherited mild fasting hyperglycemia, has been associated with >600 different mutations in the glucokinase (GK)-encoding gene (GCK). When expressed as recombinant pancreatic proteins, some mutations result in enzymes with normal/near-normal catalytic properties. The molecular mechanism(s) of GCK-MODY due to these mutations has remained elusive. Here, we aimed to explore the molecular mechanisms for two such catalytically 'normal' GCK mutations (S263P and G264S) in the F260-L270 loop of GK. When stably overexpressed in HEK293 cells and MIN6 β-cells, the S263P- and G264S-encoded mutations generated misfolded proteins with an increased rate of degradation (S263P>G264S) by the protein quality control machinery, and a propensity to self-associate (G264S>S263P) and form dimers (SDS resistant) and aggregates (partly Triton X-100 insoluble), as determined by pulse-chase experiments and subcellular fractionation. Thus, the GCK-MODY mutations S263P and G264S lead to protein misfolding causing destabilization, cellular dimerization/aggregation and enhanced rate of degradation. In silico predicted conformational changes of the F260-L270 loop structure are considered to mediate the dimerization of both mutant proteins by a domain swapping mechanism. Thus, similar properties may represent the molecular mechanisms for additional unexplained GCK-MODY mutations, and may also contribute to the disease mechanism in other previously characterized GCK-MODY inactivating mutations. Copyright © 2012 Elsevier B.V. All rights reserved.

  14. Circulating ghrelin level is higher in HNF1A-MODY and GCK-MODY than in polygenic forms of diabetes mellitus.

    Science.gov (United States)

    Nowak, Natalia; Hohendorff, Jerzy; Solecka, Iwona; Szopa, Magdalena; Skupien, Jan; Kiec-Wilk, Beata; Mlynarski, Wojciech; Malecki, Maciej T

    2015-12-01

    Ghrelin is a hormone that regulates appetite. It is likely to be involved in the pathophysiology of varying forms of diabetes. In animal studies, the ghrelin expression was regulated by the hepatocyte nuclear factor 1 alpha (HNF1A). Mutations of the HNF1A gene cause maturity onset diabetes of the young (MODY). We aimed to assess the circulating ghrelin levels in HNF1A-MODY and in other types of diabetes and to evaluate its association with HNF1A mutation status. Our cohort included 46 diabetic HNF1A gene mutation carriers, 55 type 2 diabetes (T2DM) subjects, 42 type 1 diabetes (T1DM) patients, and 31 glucokinase (GCK) gene mutation carriers with diabetes as well as 51 healthy controls. Plasma ghrelin concentration was measured using the immunoenzymatic assay with polyclonal antibody against the C-terminal fragment of its acylated and desacylated forms. Ghrelin concentrations were 0.75 ± 0.32, 0.70 ± 0.21, 0.50 ± 0.20, and 0.40 ± 0.16 ng/ml in patients with HNF1A-MODY, GCK-MODY, T1DM, and T2DM, respectively. The ghrelin levels were higher in HNF1A-MODY and GCK-MODY than in T1DM and T2DM (p MODY groups and common diabetes types remained significant. Analysis by a HNF1A mutation type indicated that ghrelin concentration is similar in patients with different types of sequence differences. Plasma ghrelin level is higher in HNF1A-MODY and GCK-MODY than in the common polygenic forms of diabetes.

  15. Maturity-onset diabetes of the young (MODY) in Brazil: Establishment of a national registry and appraisal of available genetic and clinical data.

    Science.gov (United States)

    Giuffrida, Fernando M A; Moises, Regina S; Weinert, Leticia S; Calliari, Luis E; Manna, Thais Della; Dotto, Renata P; Franco, Luciana F; Caetano, Lilian A; Teles, Milena G; Lima, Renata Andrade; Alves, Crésio; Dib, Sergio A; Silveiro, Sandra P; Dias-da-Silva, Magnus R; Reis, Andre F

    2017-01-01

    Maturity-Onset Diabetes of the Young (MODY) comprises a heterogeneous group of monogenic forms of diabetes caused by mutations in at least 14 genes, but mostly by mutations in Glucokinase (GCK) and hepatocyte nuclear factor-1 homeobox A (HNF1A). This study aims to establish a national registry of MODY cases in Brazilian patients, assessing published and unpublished data. 311 patients with clinical characteristics of MODY were analyzed, with unpublished data on 298 individuals described in 12 previous publications and 13 newly described cases in this report. 72 individuals had GCK mutations, 9 described in Brazilian individuals for the first time. One previously unpublished novel GCK mutation, Gly178Ala, was found in one family. 31 individuals had HNF1A mutations, 2 described for the first time in Brazilian individuals. Comparisons of GCK probands vs HNF1A: age 16±11 vs 35±20years; age at diagnosis 11±8 vs 21±7years; BMI 19±6 vs 25±6kg/m 2 ; sulfonylurea users 5 vs 83%; insulin users 5 vs 17%; presence of arterial hypertension 0 vs. 33%, all pMODY cases in Brazil are due to GCK mutations. In agreement with other studied populations, novel mutations are common. Only 14% of patients with familial diabetes carry a HNF1A mutation. Diagnosis of other rare forms of MODY is still a challenge in Brazilian population, as well as adequate strategies to screen individuals for molecular diagnosis. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  16. [Clinical parameters for molecular testing of Maturity Onset Diabetes of the Young (MODY)].

    Science.gov (United States)

    Datz, N; Nestoris, C; von Schütz, W; Danne, T; Driesel, A J; Maringa, M; Kordonouri, O

    2011-05-01

    Monogenic forms of diabetes are often diagnosed by chance, due to the variety of clinical presentation and limited experience of the diabetologists with this kind of diabetes. Aim of this study was to evaluate clinical parameters for an efficient screening. Clinical parameters were: negative diabetes-specific antibodies at onset of diabetes, positive family history of diabetes, and low to moderate insulin requirements after one year of diabetes treatment. Molecular testing was performed through sequencing of the programming regions of HNF-4alpha (MODY 1), glucokinase (MODY 2) and HNF-1alpha/TCF1 (MODY 3) and in one patient the HNF-1beta/TCF2 region (MODY 5). 39 of 292 patients treated with insulin were negative for GADA and IA2A, and 8 (20.5%) patients fulfilled both other criteria. Positive molecular results were found in five (63%) patients (two with MODY 2, two with MODY 3, one with MODY 5). At diabetes onset, the mean age of the 5 patients with MODY was 10.6 ± 5.3 yrs (range 2.6-15 yrs), HbA(1c) was 8.4 ± 3.1 % (6.5-13.9%), mean diabetes duration until diagnosis of MODY was 3.3 ± 3.6 yrs (0.8-9.6 yrs) with insulin requirements of 0.44 ± 0.17 U/kg/d (0.2-0.6 U/kg/d). Patients with MODY 3 were changed from insulin to repaglinide, those with MODY 2 were recommended discontinuing insulin treatment. In patients with negative diabetes-specific antibodies at onset of diabetes, with a positive family history, and low to moderate insulin needs a genetic screening for MODY is indicated. Watchful consideration of these clinical parameters may lead to an early genetic testing, and to an adequate treatment. © Georg Thieme Verlag KG Stuttgart · New York.

  17. Mutations in HNF1A Result in Marked Alterations of Plasma Glycan Profile

    Science.gov (United States)

    Thanabalasingham, Gaya; Huffman, Jennifer E.; Kattla, Jayesh J.; Novokmet, Mislav; Rudan, Igor; Gloyn, Anna L.; Hayward, Caroline; Adamczyk, Barbara; Reynolds, Rebecca M.; Muzinic, Ana; Hassanali, Neelam; Pucic, Maja; Bennett, Amanda J.; Essafi, Abdelkader; Polasek, Ozren; Mughal, Saima A.; Redzic, Irma; Primorac, Dragan; Zgaga, Lina; Kolcic, Ivana; Hansen, Torben; Gasperikova, Daniela; Tjora, Erling; Strachan, Mark W.J.; Nielsen, Trine; Stanik, Juraj; Klimes, Iwar; Pedersen, Oluf B.; Njølstad, Pål R.; Wild, Sarah H.; Gyllensten, Ulf; Gornik, Olga; Wilson, James F.; Hastie, Nicholas D.; Campbell, Harry; McCarthy, Mark I.; Rudd, Pauline M.; Owen, Katharine R.; Lauc, Gordan; Wright, Alan F.

    2013-01-01

    A recent genome-wide association study identified hepatocyte nuclear factor 1-α (HNF1A) as a key regulator of fucosylation. We hypothesized that loss-of-function HNF1A mutations causal for maturity-onset diabetes of the young (MODY) would display altered fucosylation of N-linked glycans on plasma proteins and that glycan biomarkers could improve the efficiency of a diagnosis of HNF1A-MODY. In a pilot comparison of 33 subjects with HNF1A-MODY and 41 subjects with type 2 diabetes, 15 of 29 glycan measurements differed between the two groups. The DG9-glycan index, which is the ratio of fucosylated to nonfucosylated triantennary glycans, provided optimum discrimination in the pilot study and was examined further among additional subjects with HNF1A-MODY (n = 188), glucokinase (GCK)-MODY (n = 118), hepatocyte nuclear factor 4-α (HNF4A)-MODY (n = 40), type 1 diabetes (n = 98), type 2 diabetes (n = 167), and nondiabetic controls (n = 98). The DG9-glycan index was markedly lower in HNF1A-MODY than in controls or other diabetes subtypes, offered good discrimination between HNF1A-MODY and both type 1 and type 2 diabetes (C statistic ≥0.90), and enabled us to detect three previously undetected HNF1A mutations in patients with diabetes. In conclusion, glycan profiles are altered substantially in HNF1A-MODY, and the DG9-glycan index has potential clinical value as a diagnostic biomarker of HNF1A dysfunction. PMID:23274891

  18. Chronic Mild Hyperglycemia in GCK-MODY Patients Does Not Increase Carotid Intima-Media Thickness

    Directory of Open Access Journals (Sweden)

    Stepanka Pruhova

    2013-01-01

    Full Text Available Aim. GCK-MODY is an autosomal dominant form of diabetes caused by heterozygous mutations in the glucokinase gene leading to a lifelong mild hyperglycemia. The risk of macrovascular complications is considered low, but studies are limited. We, therefore, investigated the carotid intima-media thickness (CIMT as an indicator of macrovascular complications in a group of patients with GCK-MODY. Methods. Twenty-seven GCK mutation carriers and 24 controls recruited among their first-degree relatives were compared, all aging over 35 years. The CIMT was tested using a high-resolution B-mode carotid ultrasonography. Medical history, anthropometry, and biochemical blood workup were obtained. Results. The mean CIMT was 0.707 ± 0.215 mm (mean ± SD in GCK mutation carriers and 0.690 ± 0.180 mm in control individuals. When adjusted for age, gender, and family status, the estimated mean difference in CIMT between the two groups increased to 0.049 mm (P=0.19. No difference was detected for other characteristics, with the exception of fasting blood glucose (GCK-MODY 7.6 mmol/L ± 1.2 (136.4 mg/dL; controls 5.3 mmol/L ± 0.3 (95.4 mg/dL; P<0.0001 and glycated hemoglobin HbA1c (GCK-MODY 6.9% ± 1.0%, 52 mmol/mol ± 10; controls 5.7% ± 0.4%, 39 mmol/mol ± 3; P<0.0001. The frequency of myocardial infarction and ischemic stroke did not differ between groups. Conclusion. Our data indicate that the persistent hyperglycemia in GCK-MODY is associated with a low risk of developing diabetic macrovascular complications.

  19. Monogenic diabetes in children and young adults: Challenges for researcher, clinician and patient

    Science.gov (United States)

    2006-01-01

    Monogenic diabetes results from one or more mutations in a single gene which might hence be rare but has great impact leading to diabetes at a very young age. It has resulted in great challenges for researchers elucidating the aetiology of diabetes and related features in other organ systems, for clinicians specifying a diagnosis that leads to improved genetic counselling, predicting of clinical course and changes in treatment, and for patients to altered treatment that has lead to coming off insulin and injections with no alternative (Glucokinase mutations), insulin injections being replaced by tablets (e.g. low dose in HNFα or high dose in potassium channel defects -Kir6.2 and SUR1) or with tablets in addition to insulin (e.g. metformin in insulin resistant syndromes). Genetic testing requires guidance to test for what gene especially given limited resources. Monogenic diabetes should be considered in any diabetic patient who has features inconsistent with their current diagnosis (unspecified neonatal diabetes, type 1 or type 2 diabetes) and clinical features of a specific subtype of monogenic diabetes (neonatal diabetes, familial diabetes, mild hyperglycaemia, syndromes). Guidance is given by clinical and physiological features in patient and family and the likelihood of the proposed mutation altering clinical care. In this article, I aimed to provide insight in the genes and mutations involved in insulin synthesis, secretion, and resistance, and to provide guidance for genetic testing by showing the clinical and physiological features and tests for each specified diagnosis as well as the opportunities for treatment. PMID:17186387

  20. Eugenosedin-A improves glucose metabolism and inhibits MAPKs expression in streptozotocin/nicotinamide-induced diabetic rats

    Directory of Open Access Journals (Sweden)

    Kuo-Ping Shen

    2018-03-01

    Full Text Available This study examined the effects of eugenosedin-A (Eu-A in a streptozotocin (STZ/nicotinamide-induced rat model of type II diabetes mellitus (T2DM. Six-week-old Sprague–Dawley rats were randomly divided into three groups: (1 RD group, normal rats fed a regular diet (RD, (2 DM group, T2DM rats fed a high-fat diet, and (3 Eu-A group, T2DM rats fed a high fat diet plus oral Eu-A (5 mg/kg/day. After 30 days, the DM group had higher body weight, higher blood glucose and lower insulin levels than the RD group. The DM group also had increased protein expression of glycogen synthase kinase (GSK in liver and skeletal muscle and decreased protein expression of insulin receptor (IR, insulin receptor substrate-1 (IRS-1, IRS-2, AMP-activated protein kinase (AMPK, glucose transporter-4 (GLUT-4, glucokinase (GCK, and peroxisome proliferator-activated receptor γ (PPAR-γ. STZ/nicotinamide-induced T2DM increased the expression of mitogen-activated protein kinases (MAPKs: p38, ERK, JNK and inflammatory p65 protein. In the Eu-A treated T2DM rats, however, blood glucose was attenuated and the insulin concentration stimulated. Changes in IR, IRS-1 and IRS-2 proteins as well as AMPK, GLUT-4, GCK, GSK, PPAR-γ, MAPKs, and inflammatory p65 proteins were ameliorated. These results suggested that Eu-A alleviates STZ/nicotinamide-induced hyperglycemia by improving insulin levels and glucose metabolism, and inhibiting the MAPKs- and p65-mediated inflammatory pathway.

  1. Interactive effects of naphthalene treatment and the onset of vitellogenesis on energy metabolism in liver and gonad, and plasma steroid hormones of rainbow trout Oncorhynchus mykiss.

    Science.gov (United States)

    Tintos, Adrián; Gesto, Manuel; Alvarez, Rosa; Míguez, Jesús M; Soengas, José L

    2006-10-01

    The purpose of the study was to assess in female fish the possible interaction between treatment with a polycyclic aromatic hydrocarbon (PAH) like naphthalene and the onset of vitellogenesis. In a first experiment, female rainbow trout (Oncorhynchus mykiss) at stages 2-3 (previtellogenesis) or 4 (early vitellogenesis) were intraperitoneally injected (2 microl g(-1)) with vegetable oil alone (control) or containing naphthalene (50 mg kg(-1)) to be sampled 3 h later. A second experiment was similarly designed but using fish intraperitoneally implanted (10 microl g(-1)) with slow-release coconut oil implants alone (control) or containing 50 mg naphthalene kg(-1) body mass that were sampled 3 days after injection. On each sampling time, plasma levels of cortisol and 17beta-estradiol, and several metabolic parameters in plasma, liver and gonad were assessed. In controls, early vitellogenic fish compared with previtellogenic fish displayed changes that in some cases are confirmatory of previous studies whereas in other cases provide new information in plasma (increased amino acid levels), liver (decreased capacity for exporting glucose and reduced amino acid levels) and gonad (decreased amino acid levels). Naphthalene treatment produced in previtellogenic fish decreased 17beta-estradiol levels in plasma, increased plasma glucose or decreased liver gluconeogenic capacity whereas no major effects were noticed on parameters involved in lipid, amino acid and lactate metabolism. Differential effects of naphthalene treatment were noticed in early vitellogenic fish such as decreased 17beta-estradiol and glucose levels in plasma, increased hexokinase and glucokinase and lack of changes in fructose 1,6-bisphosphatase activities in liver, and a lower decrease of amino acid levels in gonad. Those alterations produced by naphthalene treatment resulted in a decreased capacity for covering the energy demand of vitellogenesis in liver and gonad that could contribute to a delay and

  2. The spectrum of HNF1A gene mutations in Greek patients with MODY3: relative frequency and identification of seven novel germline mutations.

    Science.gov (United States)

    Tatsi, Christina; Kanaka-Gantenbein, Christina; Vazeou-Gerassimidi, Adriani; Chrysis, Dionysios; Delis, Dimitrios; Tentolouris, Nikolaos; Dacou-Voutetakis, Catherine; Chrousos, George P; Sertedaki, Amalia

    2013-11-01

    Maturity-Onset Diabetes of the Young (MODY) is the most common type of monogenic diabetes accounting for 1-2% of the population with diabetes. The relative incidence of HNF1A-MODY (MODY3) is high in European countries; however, data are not available for the Greek population. The aims of this study were to determine the relative frequency of MODY3 in Greece, the type of the mutations observed, and their relation to the phenotype of the patients. Three hundred ninety-five patients were referred to our center because of suspected MODY during a period of 15 yr. The use of Denaturing Gradient Gel Electrophoresis of polymerase chain reaction amplified DNA revealed 72 patients carrying Glucokinase gene mutations (MODY2) and 8 patients carrying HNF1A gene mutations (MODY3). After using strict criteria, 54 patients were selected to be further evaluated by direct sequencing or by multiplex ligation probe amplification (MLPA) for the presence of HNF1A gene mutations. In 16 unrelated patients and 13 of their relatives, 15 mutations were identified in the HNF1A gene. Eight of these mutations were previously reported, whereas seven were novel. Clinical features, such as age of diabetes at diagnosis or severity of hyperglycemia, were not related to the mutation type or location. In our cohort of patients fulfilling strict clinical criteria for MODY, 12% carried an HNF1A gene mutation, suggesting that defects of this gene are responsible for a significant proportion of monogenic diabetes in the Greek population. No clear phenotype-genotype correlations were identified. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  3. Higher protein kinase C ζ in fatty rat liver and its effect on insulin actions in primary hepatocytes.

    Directory of Open Access Journals (Sweden)

    Wei Chen

    Full Text Available We previously showed the impairment of insulin-regulated gene expression in the primary hepatocytes from Zucker fatty (ZF rats, and its association with alterations of hepatic glucose and lipid metabolism. However, the molecular mechanism is unknown. A preliminary experiment shows that the expression level of protein kinase C ζ (PKCζ, a member of atypical PKC family, is higher in the liver and hepatocytes of ZF rats than that of Zucker lean (ZL rats. Herein, we intend to investigate the roles of atypical protein kinase C in the regulation of hepatic gene expression. The insulin-regulated hepatic gene expression was evaluated in ZL primary hepatocytes treated with atypical PKC recombinant adenoviruses. Recombinant adenovirus-mediated overexpression of PKCζ, or the other atypical PKC member PKCι/λ, alters the basal and impairs the insulin-regulated expressions of glucokinase, sterol regulatory element-binding protein 1c, the cytosolic form of phosphoenolpyruvate carboxykinase, the catalytic subunit of glucose 6-phosphatase, and insulin like growth factor-binding protein 1 in ZL primary hepatocytes. PKCζ or PKCι/λ overexpression also reduces the protein level of insulin receptor substrate 1, and the insulin-induced phosphorylation of AKT at Ser473 and Thr308. Additionally, PKCι/λ overexpression impairs the insulin-induced Prckz expression, indicating the crosstalk between PKCζ and PKCι/λ. We conclude that the PKCζ expression is elevated in hepatocytes of insulin resistant ZF rats. Overexpressions of aPKCs in primary hepatocytes impair insulin signal transduction, and in turn, the down-stream insulin-regulated gene expression. These data suggest that elevation of aPKC expression may contribute to the hepatic insulin resistance at gene expression level.

  4. Computational and Pharmacological Evaluation of Ferrocene-Based Acyl Ureas and Homoleptic Cadmium Carboxylate Derivatives for Anti-diabetic Potential

    Directory of Open Access Journals (Sweden)

    Shahar Bano

    2018-01-01

    Full Text Available We investigated possible anti-diabetic effect of ferrocene-based acyl ureas: 4-ferrocenyl aniline (PFA, 1-(4-chlorobenzoyl-3-(4-ferrocenylphenyl urea (DPC1, 1-(3-chlorobenzoyl-3-(4-ferrocenylphenyl urea (DMC1, 1-(2-chlorobenzoyl-3-(4-ferrocenylphenyl urea (DOC1 and homoleptic cadmium carboxylates: bis (diphenylacetato cadmium (II (DPAA, bis (4-chlorophenylacetato cadmium (II (CPAA, using in silico and in vivo techniques. PFA, DPC1, DMC1, DOC1, DPAA and CPAA exhibited high binding affinities (ACE ≥ −350 Kcal/mol against targets: aldose reductase, peroxisome proliferator-activated receptor γ, 11β-hydroxysteroid dehydrogenase-1, C-alpha glucosidase and glucokinase, while showed moderate affinities (ACE ≥ −250 Kcal/mol against N-alpha glucosidase, dipeptidyl peptidase-IV, phosphorylated-Akt, glycogen synthase kinase-3β, fructose-1,6-bisphosphatase and phosphoenolpyruvate carboxykinase, whereas revealed lower affinities (ACE < −250 Kcal/mol vs. alpha amylase, protein tyrosine phosphatases 1B, glycogen phosphorylase and phosphatidylinositol 3 kinase. In alloxan (300 mg/Kg-induced diabetic mice, DPAA and DPC1 (1–10 mg/Kg at day 1, 5, 10, 15, and 20th decreased blood glucose levels, compared to diabetic control group and improved the treated animals body weight. DPAA (10 mg/Kg and DPC1 (5 mg/Kg in time-dependent manner (30–120 min. enhanced tolerance of oral glucose overload in mice. DPAA and DPCI dose-dependently at 1, 5, and 10 mg/Kg decreased glycosylated hemoglobin levels in diabetic animals, as caused by metformin. These results indicate that aforementioned derivatives of ferrocene and cadmium possess anti-diabetic potential.

  5. Adult-onset hyperinsulinaemic hypoglycaemia in clinical practice: diagnosis, aetiology and management.

    Science.gov (United States)

    Challis, Benjamin G; Powlson, Andrew S; Casey, Ruth T; Pearson, Carla; Lam, Brian Y; Ma, Marcella; Pitfield, Deborah; Yeo, Giles S H; Godfrey, Edmund; Cheow, Heok K; Chatterjee, V Krishna; Carroll, Nicholas R; Shaw, Ashley; Buscombe, John R; Simpson, Helen L

    2017-10-01

    In adults with hyperinsulinaemic hypoglycaemia (HH), in particular those with insulinoma, the optimal diagnostic and management strategies remain uncertain. Here, we sought to characterise the biochemical and radiological assessment, and clinical management of adults with HH at a tertiary centre over a thirteen-year period. Clinical, biochemical, radiological and histological data were reviewed from all confirmed cases of adult-onset hyperinsulinaemic hypoglycaemia at our centre between 2003 and 2016. In a subset of patients with stage I insulinoma, whole-exome sequencing of tumour DNA was performed. Twenty-nine patients were identified (27 insulinoma, including 6 subjects with metastatic disease; 1 pro-insulin/GLP-1 co-secreting tumour; 1 activating glucokinase mutation). In all cases, hypoglycaemia (glucose ≤2.2 mmol/L) was achieved within 48 h of a supervised fast. At fast termination, subjects with stage IV insulinoma had significantly higher insulin, C-peptide and pro-insulin compared to those with insulinoma staged I-IIIB. Preoperative localisation of insulinoma was most successfully achieved with EUS. In two patients with inoperable, metastatic insulinoma, peptide receptor radionuclide therapy (PRRT) with 177 Lu-DOTATATE rapidly restored euglycaemia and lowered fasting insulin. Finally, in a subset of stage I insulinoma, whole-exome sequencing of tumour DNA identified the pathogenic Ying Yang-1 ( YY1 ) somatic mutation (c.C1115G/p.T372R) in one tumour, with all tumours exhibiting a low somatic mutation burden. Our study highlights, in particular, the utility of the 48-h fast in the diagnosis of insulinoma, EUS for tumour localisation and the value of PRRT therapy in the treatment of metastatic disease. © 2017 The authors.

  6. [Predisposition and phenotypes of gestational diabetes].

    Science.gov (United States)

    Kleinwechter, H; Demandt, N; Schäfer-Graf, U

    2014-05-01

    Gestational diabetes (GDM) is defined as glucose intolerance first diagnosed with a 75 gram oral glucose tolerance test based on IADPSG criteria which had been recently adopted by WHO. In industrial countries GDM is one of the most frequent pregnancy complications. In 2012, in Germany GDM had been diagnosed in 4,3 % of all births, overall 27,700 cases. GDM has to be considered as a preliminary stage of type 2 diabetes with insulin resistance and inadequate β-cell-compensation. Additionally, adverse metabolic profile, associations with inflammatory parameters, with D vitamin metabolism, and insufficient decline of renal threshold for glucose had been identified in women with GDM. Within 10 years after GDM roughly 50 % of the women convert to overt diabetes, mostly type 2. GDM and type 2 diabetes share potential candidate genes. In about 1 % of GDM in Caucasian women a mutation in glucokinase gene had been found (GCK-MODY). Predisposition to GDM is predominantly characterized by family history of diabetes, previous GDM in pregnancies, factors of metabolic syndrome, and unfavorable life style. The probability for GDM rises with increasing mother's age and preconceptional BMI. Via fetal programming GDM dispones to offspring obesity as early as school entry. Prevention of GDM focus on regular physical exercise, normalizing body weight before conception, reducing excess intake of animal protein and soft drinks, planning of pregnancy in younger ages, and avoiding pollutant exposition as well as smoking cessation. © Georg Thieme Verlag KG Stuttgart · New York.

  7. Recombinant Passenger Proteins Can Be Conveniently Purified by One-Step Affinity Chromatography.

    Science.gov (United States)

    Wang, Hua-zhen; Chu, Zhi-zhan; Chen, Chang-chao; Cao, Ao-cheng; Tong, Xin; Ouyang, Can-bin; Yuan, Qi-hang; Wang, Mi-nan; Wu, Zhong-kun; Wang, Hai-hong; Wang, Sheng-bin

    2015-01-01

    Fusion tag is one of the best available tools to date for enhancement of the solubility or improvement of the expression level of recombinant proteins in Escherichia coli. Typically, two consecutive affinity purification steps are often necessitated for the purification of passenger proteins. As a fusion tag, acyl carrier protein (ACP) could greatly increase the soluble expression level of Glucokinase (GlcK), α-Amylase (Amy) and GFP. When fusion protein ACP-G2-GlcK-Histag and ACP-G2-Amy-Histag, in which a protease TEV recognition site was inserted between the fusion tag and passenger protein, were coexpressed with protease TEV respectively in E. coli, the efficient intracellular processing of fusion proteins was achieved. The resulting passenger protein GlcK-Histag and Amy-Histag accumulated predominantly in a soluble form, and could be conveniently purified by one-step Ni-chelating chromatography. However, the fusion protein ACP-GFP-Histag was processed incompletely by the protease TEV coexpressed in vivo, and a large portion of the resulting target protein GFP-Histag aggregated in insoluble form, indicating that the intracellular processing may affect the solubility of cleaved passenger protein. In this context, the soluble fusion protein ACP-GFP-Histag, contained in the supernatant of E. coli cell lysate, was directly subjected to cleavage in vitro by mixing it with the clarified cell lysate of E. coli overexpressing protease TEV. Consequently, the resulting target protein GFP-Histag could accumulate predominantly in a soluble form, and be purified conveniently by one-step Ni-chelating chromatography. The approaches presented here greatly simplify the purification process of passenger proteins, and eliminate the use of large amounts of pure site-specific proteases.

  8. Effect of DHA supplementation on digestible starch utilization by rainbow trout.

    Science.gov (United States)

    Tapia-Salazar, M; Bureau, W; Panserat, S; Corraze, G; Bureau, D P

    2006-01-01

    Rainbow trout has a limited ability to utilize digestible carbohydrates efficiently. Trout feeds generally contain high levels of DHA, a fatty acid known to inhibit a number of glycolytic and lipogenic enzymes in animals. A study was conducted to determine whether carbohydrate utilization by rainbow trout might be affected by dietary DHA level. Two low-carbohydrate (digestible carbohydrate) basal diets were formulated to contain 1 (adequate) or 4 (excess) g/100 g DHA diet respectively. The two basal diets were diluted with increasing levels of digestible starch (0 %, 10 %, 20 % and 30 %, respectively) to produce eight diets. These diets were fed to fish for 12 weeks at 15 degrees C according to a pair-fed protocol that consisted of feeding the same amount of basal diet but different amounts of starch. Live weight, N and lipid gains, hepatic glycogen and plasma glucose values significantly increased, whereas feed efficiency (gain:feed) significantly decreased, with increasing starch intake (Pdigestible N intake) improved with starch supplementation but was not affected by DHA level (P>0.05). Starch increased the activity of glucokinase, pyruvate kinase, glucose 6-phosphate dehydrogenase and fatty acid synthase (P<0.05) but did not affect hexokinase and malic enzyme activity. DHA had no effect on growth but increased plasma glucose and reduced carcass lipid and liver glycogen contents (P<0.05). Glycolytic and lipogenic enzymes were not affected by DHA level, except for pyruvate kinase, which was reduced by increasing DHA level. These results suggest only a marginal effect of dietary DHA on the ability of fish to utilize carbohydrate.

  9. GLUT2 in pancreatic islets: crucial target molecule in diabetes induced with multiple low doses of streptozotocin in mice.

    Science.gov (United States)

    Wang, Z; Gleichmann, H

    1998-01-01

    In mice, diabetes can be induced by multiple low doses of streptozotocin (MLD-STZ), i.e., 40 mg/kg body wt on each of 5 consecutive days. In this model, diabetes develops only when STZ induces both beta-cell toxicity and T-cell-dependent immune reactions. The target molecule(s) of MLD-STZ-induced beta-cell toxicity are not known, however. In this study, we report that GLUT2 is a target molecule for MLD-STZ toxicity. Ex vivo, a gradual decrement of both GLUT2 protein and mRNA expression was found in pancreatic islets isolated from MLD-STZ-treated C57BL/6 male mice, whereas mRNA expression of beta-actin, glucokinase, and proinsulin remained unaffected. Significant reduction of both GLUT2 protein and mRNA expression was first noted 1 day after the third STZ injection, clearly preceding the onset of hyperglycemia. The extent of reduction increased with the number of STZ injections administered and increased over time, after the last, i.e., fifth, STZ injection. The STZ-induced reduction of GLUT2 protein and mRNA was not due to an essential loss of beta-cells, because ex vivo, not only the total RNA yield and protein content in isolated islets, but also proinsulin mRNA expression, failed to differ significantly in the differently treated groups. Furthermore, islets isolated from MLD-STZ-treated donors responded to the nonglucose secretagogue arginine in a pattern similar to that of solvent-treated donors. Interestingly, the MLD-STZ-induced reduction of both GLUT2 protein and mRNA was prevented by preinjecting mice with 5-thio-D-glucose before each STZ injection. Apparently, GLUT2 is a crucial target molecule of MLD-STZ toxicity, and this toxicity seems to precede the immune reactions against beta-cells.

  10. Influence of Background Genome on Enzymatic Characteristics of Yellow (Ay/-, Avy/-) Mice

    Science.gov (United States)

    Wolff, George L.; Pitot, Henry C.

    1973-01-01

    Identification of the fundamental polypeptide difference between yellow (Ay/-, Avy/-) and non-yellow mice is important for biomedical research because of the influence of the yellow genotype on normal and neoplastic growth and obesity. The complexity of the "yellow mouse syndrome" makes attainment of this objective dependent on the separation of those pleiotropic enzyme differences which are secondary, and depend on the background genome, from those which are primary, and depend primarily on the agouti locus genotype.—Four of nine hepatic enzyme activities assayed simultaneously differed between eight-week-old yellow (Ay/-, Avy/-) and non-yellow (A/-, a/a) male inbred and F1 hybrid mice. Among these four, only cytoplasmic malic enzyme activity was elevated in all yellow mice, as compared with the non-yellow sibs, regardless of background genome. Glucokinase, serine dehydratase, and tyrosine α-ketoglutarate transaminase activities were also changed in yellow mice, but these alterations depended on the background genome.—The ratio of malic enzyme activity to citrate-cleavage enzyme activity, possibly related to the altered fat metabolism of yellow mice, was influenced by background genome as well as by the yellow genotype.——Significant deviations of enzyme activities from mid-parent values among F1 hybrids were associated with particular background genomes; the number of such deviations was larger among yellow mice than among non-yellows and this difference was greater among C3H F1 hybrids than among C57BL/6 F1 hybrids. PMID:4405752

  11. Metabolism and fatty acid profile in fat and lean rainbow trout lines fed with vegetable oil: effect of carbohydrates.

    Directory of Open Access Journals (Sweden)

    Biju Sam Kamalam

    Full Text Available The present study investigated the effect of dietary carbohydrates on metabolism, with special focus on fatty acid bioconversion and flesh lipid composition in two rainbow trout lines divergently selected for muscle lipid content and fed with vegetable oils. These lines were chosen based on previously demonstrated potential differences in LC-PUFA synthesis and carbohydrate utilization. Applying a factorial study design, juvenile trout from the lean (L and the fat (F line were fed vegetable oil based diets with or without gelatinised starch (17.1% for 12 weeks. Blood, liver, muscle, intestine and adipose tissue were sampled after the last meal. Feed intake and growth was higher in the L line than the F line, irrespective of the diet. Moderate postprandial hyperglycemia, strong induction of hepatic glucokinase and repressed glucose-6-phosphatase transcripts confirmed the metabolic response of both lines to carbohydrate intake. Further at the transcriptional level, dietary carbohydrate in the presence of n-3 LC-PUFA deficient vegetable oils enhanced intestinal chylomicron assembly, disturbed hepatic lipid metabolism and importantly elicited a higher response of key desaturase and elongase enzymes in the liver and intestine that endorsed our hypothesis. PPARγ was identified as the factor mediating this dietary regulation of fatty acid bioconversion enzymes in the liver. However, these molecular changes were not sufficient to modify the fatty acid composition of muscle or liver. Concerning the genotype effect, there was no evidence of substantial genotypic difference in lipid metabolism, LC-PUFA synthesis and flesh fatty acid profile when fed with vegetable oils. The minor reduction in plasma glucose and triglyceride levels in the F line was linked to potentially higher glucose and lipid uptake in the muscle. Overall, these data emphasize the importance of dietary macro-nutrient interface in evolving fish nutrition strategies.

  12. Metabolism and fatty acid profile in fat and lean rainbow trout lines fed with vegetable oil: effect of carbohydrates.

    Science.gov (United States)

    Kamalam, Biju Sam; Médale, Françoise; Larroquet, Laurence; Corraze, Geneviève; Panserat, Stephane

    2013-01-01

    The present study investigated the effect of dietary carbohydrates on metabolism, with special focus on fatty acid bioconversion and flesh lipid composition in two rainbow trout lines divergently selected for muscle lipid content and fed with vegetable oils. These lines were chosen based on previously demonstrated potential differences in LC-PUFA synthesis and carbohydrate utilization. Applying a factorial study design, juvenile trout from the lean (L) and the fat (F) line were fed vegetable oil based diets with or without gelatinised starch (17.1%) for 12 weeks. Blood, liver, muscle, intestine and adipose tissue were sampled after the last meal. Feed intake and growth was higher in the L line than the F line, irrespective of the diet. Moderate postprandial hyperglycemia, strong induction of hepatic glucokinase and repressed glucose-6-phosphatase transcripts confirmed the metabolic response of both lines to carbohydrate intake. Further at the transcriptional level, dietary carbohydrate in the presence of n-3 LC-PUFA deficient vegetable oils enhanced intestinal chylomicron assembly, disturbed hepatic lipid metabolism and importantly elicited a higher response of key desaturase and elongase enzymes in the liver and intestine that endorsed our hypothesis. PPARγ was identified as the factor mediating this dietary regulation of fatty acid bioconversion enzymes in the liver. However, these molecular changes were not sufficient to modify the fatty acid composition of muscle or liver. Concerning the genotype effect, there was no evidence of substantial genotypic difference in lipid metabolism, LC-PUFA synthesis and flesh fatty acid profile when fed with vegetable oils. The minor reduction in plasma glucose and triglyceride levels in the F line was linked to potentially higher glucose and lipid uptake in the muscle. Overall, these data emphasize the importance of dietary macro-nutrient interface in evolving fish nutrition strategies.

  13. Glucose metabolism and recycling by hepatocytes of OB/OB and ob/ob mice

    International Nuclear Information System (INIS)

    Lahtela, J.T.; Wals, P.A.; Katz, J.

    1990-01-01

    Hepatocytes were prepared from livers of ob/ob (obese diabetic) mice and their lean (OB/OB) siblings that had been fasted for 24 h. The hepatocytes were incubated with [U-14C, 2-3H]-, [U-14C, 3-3H]-, and [U-14C, 6-3H]glucose at concentrations from 20 to 120 mM. 14C was recovered mainly in CO2, glycogen, and lactate. Tritium was recovered in water and glycogen. The yield in labeled products from [2-3H]glucose ranged from two to three times that from [U-14C]glucose. The yields from [3-3H]- and [6-3H]glucose were similar, and 1.3-1.7 times that from [U-14C]glucose. At 40 mM, total utilization of glucose by obese mice was about twice that for lean mice, but there was little difference at 120 mM. The rate of recycling between glucose and glucose 6-phosphate was calculated. An equation to calculate the rate of recycling of glucose from the 2-3H/U-14C ratio in glycogen is derived in the APPENDIX. Our results show that (1) the utilization of glucose by hepatocytes from obese diabetic mice exceeds that of their lean controls, (2) the rate of glucose phosphorylation in both groups greatly exceeds glucose uptake and the rate of glycogen synthesis, (3) glucose phosphorylation represents a difference between a high glucokinase rate and hydrolysis of glucose 6-phosphate, and (4) recycling of glucose carbon between glucose 6-phosphate and pyruvate occurs within mouse hepatocytes

  14. Prevalence of monogenic diabetes amongst Polish children after a nationwide genetic screening campaign.

    Science.gov (United States)

    Fendler, W; Borowiec, M; Baranowska-Jazwiecka, A; Szadkowska, A; Skala-Zamorowska, E; Deja, G; Jarosz-Chobot, P; Techmanska, I; Bautembach-Minkowska, J; Mysliwiec, M; Zmyslowska, A; Pietrzak, I; Malecki, M T; Mlynarski, W

    2012-10-01

    The aim of this study was to study dynamic changes in the prevalence of different types of diabetes in paediatric populations in Poland, with a specific focus on monogenic diabetes (MD). Using epidemiologic data (PolPeDiab Collaboration) and nationwide genetic test results (TEAM Programme), we compared the prevalence of type 1, type 2 and cystic fibrosis-related diabetes (CFRD) and MD. Genetically confirmed MD included MODY, neonatal diabetes and Wolfram and Alström syndromes. The study covered all children aged 0-18 years treated for diabetes between 2005 and 2011 in three regions, inhabited by 23.7% (1,989,988) of Polish children, with a low prevalence of childhood obesity (type 1 diabetes showed a continuous increase, from 96 to 138/100,000 children. The prevalence of type 2 diabetes and CFRD also increased, from 0.3 to 1.01/100,000 children and from 0.1 to 0.95/100,000 children, respectively. The prevalence of MD was stable at between 4.2 and 4.6/100,000 children, accounting for 3.1-4.2% of children with diabetes, with glucokinase (GCK)-MODY being the most frequent type, amounting to 83% of patients with MD. The percentage of positive test results decreased with the number of referrals, suggesting that children with the highest probability of MD were referred initially, followed by those with a less clear-cut phenotype. The prevalence of neonatal diabetes equalled 1 in 300,000 children. The prevalence of MD in a paediatric population with a low prevalence of obesity remains stable and is nearly fivefold higher than that of type 2 diabetes and CFRD, justifying a need for increased access to genetic diagnostic procedures in diabetic children.

  15. A general framework for thermodynamically consistent parameterization and efficient sampling of enzymatic reactions.

    Directory of Open Access Journals (Sweden)

    Pedro Saa

    2015-04-01

    Full Text Available Kinetic models provide the means to understand and predict the dynamic behaviour of enzymes upon different perturbations. Despite their obvious advantages, classical parameterizations require large amounts of data to fit their parameters. Particularly, enzymes displaying complex reaction and regulatory (allosteric mechanisms require a great number of parameters and are therefore often represented by approximate formulae, thereby facilitating the fitting but ignoring many real kinetic behaviours. Here, we show that full exploration of the plausible kinetic space for any enzyme can be achieved using sampling strategies provided a thermodynamically feasible parameterization is used. To this end, we developed a General Reaction Assembly and Sampling Platform (GRASP capable of consistently parameterizing and sampling accurate kinetic models using minimal reference data. The former integrates the generalized MWC model and the elementary reaction formalism. By formulating the appropriate thermodynamic constraints, our framework enables parameterization of any oligomeric enzyme kinetics without sacrificing complexity or using simplifying assumptions. This thermodynamically safe parameterization relies on the definition of a reference state upon which feasible parameter sets can be efficiently sampled. Uniform sampling of the kinetics space enabled dissecting enzyme catalysis and revealing the impact of thermodynamics on reaction kinetics. Our analysis distinguished three reaction elasticity regions for common biochemical reactions: a steep linear region (0> ΔGr >-2 kJ/mol, a transition region (-2> ΔGr >-20 kJ/mol and a constant elasticity region (ΔGr <-20 kJ/mol. We also applied this framework to model more complex kinetic behaviours such as the monomeric cooperativity of the mammalian glucokinase and the ultrasensitive response of the phosphoenolpyruvate carboxylase of Escherichia coli. In both cases, our approach described appropriately not only

  16. Lack of liver glycogen causes hepatic insulin resistance and steatosis in mice.

    Science.gov (United States)

    Irimia, Jose M; Meyer, Catalina M; Segvich, Dyann M; Surendran, Sneha; DePaoli-Roach, Anna A; Morral, Nuria; Roach, Peter J

    2017-06-23

    Disruption of the Gys2 gene encoding the liver isoform of glycogen synthase generates a mouse strain (LGSKO) that almost completely lacks hepatic glycogen, has impaired glucose disposal, and is pre-disposed to entering the fasted state. This study investigated how the lack of liver glycogen increases fat accumulation and the development of liver insulin resistance. Insulin signaling in LGSKO mice was reduced in liver, but not muscle, suggesting an organ-specific defect. Phosphorylation of components of the hepatic insulin-signaling pathway, namely IRS1, Akt, and GSK3, was decreased in LGSKO mice. Moreover, insulin stimulation of their phosphorylation was significantly suppressed, both temporally and in an insulin dose response. Phosphorylation of the insulin-regulated transcription factor FoxO1 was somewhat reduced and insulin treatment did not elicit normal translocation of FoxO1 out of the nucleus. Fat overaccumulated in LGSKO livers, showing an aberrant distribution in the acinus, an increase not explained by a reduction in hepatic triglyceride export. Rather, when administered orally to fasted mice, glucose was directed toward hepatic lipogenesis as judged by the activity, protein levels, and expression of several fatty acid synthesis genes, namely, acetyl-CoA carboxylase, fatty acid synthase, SREBP1c, chREBP, glucokinase, and pyruvate kinase. Furthermore, using cultured primary hepatocytes, we found that lipogenesis was increased by 40% in LGSKO cells compared with controls. Of note, the hepatic insulin resistance was not associated with increased levels of pro-inflammatory markers. Our results suggest that loss of liver glycogen synthesis diverts glucose toward fat synthesis, correlating with impaired hepatic insulin signaling and glucose disposal. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  17. Kinetics of Hesperetin for Liver Fortification in gamma-Irradiated Mice

    International Nuclear Information System (INIS)

    Tawfik, S.S.

    2011-01-01

    Hesperetin (3',5,7-trihydroxy-4'-methoxyflavonone), the aglycone of the flavanone glycosides hesperidin, exerts pharmacological properties such as antioxidation, anti-inflammation, blood lipid and cholesterol lowering is effectively used as a supplemental agent in the treatment protocols of complementary settings. Four groups were prepared: Control group: received 0.5 ml normal saline for 7 days. Hesperetin group: Mice received 7 doses of hesperetin injections (100 mg/ kg body wt/ day). Irradiated group: Mice submitted to total body irradiation with 4 Gy gamma-rays. Protected group (Hesperetin plus irradiation): Mice received hesperetin for 7 days and then submitted to 4 Gy of gamma-rays. The mice were sacrificed at 24 h, 1 week and 2 weeks after the end of the experimental treatments. Irradiated mice exhibited significant hyperglycaemia and augmented hepatic glycogen after the first day and 1 week but significant hypoglycemia and reducing hepatic glycogen after 2 weeks. Also, they exhibited significant increased serum total cholesterol (TC) and triacylglycerols (TG) and decreased hepatic TC and TG after 1 and 2 weeks. This treatment also resulted in a significant dropped in hepatic glucokinase (GK), glucose-6-phosphatase (G6P) and phosphoenolpyruvate carboxykinase (PEPCK) activities after 1 and 2 weeks. Hesperetin injections modulated the serum glucose and hepatic glycogen, adjusted TC and TG in both serum and liver and ameliorated the lessening in hepatic GK, G6P and PEPCK. The attending results demonstrated that hesperetn treatment modulated the biochemical symptoms of radiation disorders in mice. In conclusion, administration of hesperetin may have a useful role in modulating oxidative stress induced by exposure to gamma-radiation by improving the natural antioxidant mechanism and fortification liver functions

  18. Increased glucose metabolism and alpha-glucosidase inhibition in Cordyceps militaris water extract-treated HepG2 cells

    Science.gov (United States)

    Kim, Dae Jung; Kang, Yun Hwan; Kim, Kyoung Kon; Kim, Tae Woo; Park, Jae Bong

    2017-01-01

    BACKGROUND/OBJECTIVES Recent living condition improvements, changes in dietary habits, and reductions in physical activity are contributing to an increase in metabolic syndrome symptoms including diabetes and obesity. Through such societal developments, humankind is continuously exposed to metabolic diseases such as diabetes, and the number of the victims is increasing. This study investigated Cordyceps militaris water extract (CMW)-induced glucose uptake in HepG2 cells and the effect of CMW treatment on glucose metabolism. MATERIALS/METHODS Colorimetric assay kits were used to determine the glucokinase (GK) and pyruvate dehydrogenase (PDH) activities, glucose uptake, and glycogen content. Either RT-PCR or western blot analysis was performed for quantitation of glucose transporter 2 (GLUT2), hepatocyte nuclear factor 1 alpha (HNF-1α), phosphatidylinositol 3-kinase (PI3k), protein kinase B (Akt), phosphorylated AMP-activated protein kinase (pAMPK), phosphoenolpyruvate carboxykinase, GK, PDH, and glycogen synthase kinase 3 beta (GSK-3β) expression levels. The α-glucosidase inhibitory activities of acarbose and CMW were evaluated by absorbance measurement. RESULTS CMW induced glucose uptake in HepG2 cells by increasing GLUT2 through HNF-1α expression stimulation. Glucose in the cells increased the CMW-induced phosphorylation of AMPK. In turn, glycolysis was stimulated, and glyconeogenesis was inhibited. Furthermore, by studying the mechanism of action of PI3k, Akt, and GSK-3β, and measuring glycogen content, the study confirmed that the glucose was stored in the liver as glycogen. Finally, CMW resulted in a higher level of α-glucosidase inhibitory activity than that from acarbose. CONCLUSION CMW induced the uptake of glucose into HepG2 cells, as well, it induced metabolism of the absorbed glucose. It is concluded that CMW is a candidate or potential use in diabetes prevention and treatment. PMID:28584574

  19. Effects of the antitumor drug OSI-906, a dual inhibitor of IGF-1 receptor and insulin receptor, on the glycemic control, β-cell functions, and β-cell proliferation in male mice.

    Science.gov (United States)

    Shirakawa, Jun; Okuyama, Tomoko; Yoshida, Eiko; Shimizu, Mari; Horigome, Yuka; Tuno, Takayuki; Hayasaka, Moe; Abe, Shiori; Fuse, Masahiro; Togashi, Yu; Terauchi, Yasuo

    2014-06-01

    The IGF-1 receptor has become a therapeutic target for the treatment of cancer. The efficacy of OSI-906 (linstinib), a dual inhibitor of IGF-1 receptor and insulin receptor, for solid cancers has been examined in clinical trials. The effects of OSI-906, however, on the blood glucose levels and pancreatic β-cell functions have not yet been reported. We investigated the impact of OSI-906 on glycemic control, insulin secretion, β-cell mass, and β-cell proliferation in male mice. Oral administration of OSI-906 worsened glucose tolerance in a dose-dependent manner in the wild-type mice. OSI-906 at a dose equivalent to the clinical daily dose (7.5 mg/kg) transiently evoked glucose intolerance and hyperinsulinemia. Insulin receptor substrate (IRS)-2-deficient mice and mice with diet-induced obesity, both models of peripheral insulin resistance, exhibited more severe glucose intolerance after OSI-906 administration than glucokinase-haploinsufficient mice, a model of impaired insulin secretion. Phloridzin improved the hyperglycemia induced by OSI-906 in mice. In vitro, OSI-906 showed no effect on insulin secretion from isolated islets. After daily administration of OSI-906 for a week to mice, the β-cell mass and β-cell proliferation rate were significantly increased. The insulin signals in the β-cells were apparently unaffected in those mice. Taken together, the results suggest that OSI-906 could exacerbate diabetes, especially in patients with insulin resistance. On the other hand, the results suggest that the β-cell mass may expand in response to chemotherapy with this drug.

  20. CNC-bZIP protein Nrf1-dependent regulation of glucose-stimulated insulin secretion.

    Science.gov (United States)

    Zheng, Hongzhi; Fu, Jingqi; Xue, Peng; Zhao, Rui; Dong, Jian; Liu, Dianxin; Yamamoto, Masayuki; Tong, Qingchun; Teng, Weiping; Qu, Weidong; Zhang, Qiang; Andersen, Melvin E; Pi, Jingbo

    2015-04-01

    The inability of pancreatic β-cells to secrete sufficient insulin in response to glucose stimulation is a major contributing factor to the development of type 2 diabetes (T2D). We investigated both the in vitro and in vivo effects of deficiency of nuclear factor-erythroid 2-related factor 1 (Nrf1) in β-cells on β-cell function and glucose homeostasis. Silencing of Nrf1 in β-cells leads to a pre-T2D phenotype with disrupted glucose metabolism and impaired insulin secretion. Specifically, MIN6 β-cells with stable knockdown of Nrf1 (Nrf1-KD) and isolated islets from β-cell-specific Nrf1-knockout [Nrf1(b)-KO] mice displayed impaired glucose responsiveness, including elevated basal insulin release and decreased glucose-stimulated insulin secretion (GSIS). Nrf1(b)-KO mice exhibited severe fasting hyperinsulinemia, reduced GSIS, and glucose intolerance. Silencing of Nrf1 in MIN6 cells resulted in oxidative stress and altered glucose metabolism, with increases in both glucose uptake and aerobic glycolysis, which is associated with the elevated basal insulin release and reduced glucose responsiveness. The elevated glycolysis and reduced glucose responsiveness due to Nrf1 silencing likely result from altered expression of glucose metabolic enzymes, with induction of high-affinity hexokinase 1 and suppression of low-affinity glucokinase. Our study demonstrated a novel role of Nrf1 in regulating glucose metabolism and insulin secretion in β-cells and characterized Nrf1 as a key transcription factor that regulates the coupling of glycolysis and mitochondrial metabolism and GSIS. Nrf1 plays critical roles in regulating glucose metabolism, mitochondrial function, and insulin secretion, suggesting that Nrf1 may be a novel target to improve the function of insulin-secreting β-cells.

  1. 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.

    Science.gov (United States)

    McCarty, Mark F

    2016-10-01

    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

  2. Chronic suppression of acetyl-CoA carboxylase 1 in beta-cells impairs insulin secretion via inhibition of glucose rather than lipid metabolism.

    Science.gov (United States)

    Ronnebaum, Sarah M; Joseph, Jamie W; Ilkayeva, Olga; Burgess, Shawn C; Lu, Danhong; Becker, Thomas C; Sherry, A Dean; Newgard, Christopher B

    2008-05-23

    Acetyl-CoA carboxylase 1 (ACC1) currently is being investigated as a target for treatment of obesity-associated dyslipidemia and insulin resistance. To investigate the effects of ACC1 inhibition on insulin secretion, three small interfering RNA (siRNA) duplexes targeting ACC1 (siACC1) were transfected into the INS-1-derived cell line, 832/13; the most efficacious duplex was also cloned into an adenovirus and used to transduce isolated rat islets. Delivery of the siACC1 duplexes decreased ACC1 mRNA by 60-80% in 832/13 cells and islets and enzyme activity by 46% compared with cells treated with a non-targeted siRNA. Delivery of siACC1 decreased glucose-stimulated insulin secretion (GSIS) by 70% in 832/13 cells and by 33% in islets. Surprisingly, siACC1 treatment decreased glucose oxidation by 49%, and the ATP:ADP ratio by 52%, accompanied by clear decreases in pyruvate cycling activity and tricarboxylic acid cycle intermediates. Exposure of siACC1-treated cells to the pyruvate cycling substrate dimethylmalate restored GSIS to normal without recovery of the depressed ATP:ADP ratio. In siACC1-treated cells, glucokinase protein levels were decreased by 25%, which correlated with a 36% decrease in glycogen synthesis and a 33% decrease in glycolytic flux. Furthermore, acute addition of the ACC1 inhibitor 5-(tetradecyloxy)-2-furoic acid (TOFA) to beta-cells suppressed [(14)C]glucose incorporation into lipids but had no effect on GSIS, whereas chronic TOFA administration suppressed GSIS and glucose metabolism. In sum, chronic, but not acute, suppression of ACC1 activity impairs GSIS via inhibition of glucose rather than lipid metabolism. These findings raise concerns about the use of ACC inhibitors for diabetes therapy.

  3. Chronic Suppression of Acetyl-CoA Carboxylase 1 in β-Cells Impairs Insulin Secretion via Inhibition of Glucose Rather Than Lipid Metabolism*

    Science.gov (United States)

    Ronnebaum, Sarah M.; Joseph, Jamie W.; Ilkayeva, Olga; Burgess, Shawn C.; Lu, Danhong; Becker, Thomas C.; Sherry, A. Dean; Newgard, Christopher B.

    2008-01-01

    Acetyl-CoA carboxylase 1 (ACC1) currently is being investigated as a target for treatment of obesity-associated dyslipidemia and insulin resistance. To investigate the effects of ACC1 inhibition on insulin secretion, three small interfering RNA (siRNA) duplexes targeting ACC1 (siACC1) were transfected into the INS-1-derived cell line, 832/13; the most efficacious duplex was also cloned into an adenovirus and used to transduce isolated rat islets. Delivery of the siACC1 duplexes decreased ACC1 mRNA by 60–80% in 832/13 cells and islets and enzyme activity by 46% compared with cells treated with a non-targeted siRNA. Delivery of siACC1 decreased glucose-stimulated insulin secretion (GSIS) by 70% in 832/13 cells and by 33% in islets. Surprisingly, siACC1 treatment decreased glucose oxidation by 49%, and the ATP:ADP ratio by 52%, accompanied by clear decreases in pyruvate cycling activity and tricarboxylic acid cycle intermediates. Exposure of siACC1-treated cells to the pyruvate cycling substrate dimethylmalate restored GSIS to normal without recovery of the depressed ATP:ADP ratio. In siACC1-treated cells, glucokinase protein levels were decreased by 25%, which correlated with a 36% decrease in glycogen synthesis and a 33% decrease in glycolytic flux. Furthermore, acute addition of the ACC1 inhibitor 5-(tetradecyloxy)-2-furoic acid (TOFA) to β-cells suppressed [14C]glucose incorporation into lipids but had no effect on GSIS, whereas chronic TOFA administration suppressed GSIS and glucose metabolism. In sum, chronic, but not acute, suppression of ACC1 activity impairs GSIS via inhibition of glucose rather than lipid metabolism. These findings raise concerns about the use of ACC inhibitors for diabetes therapy. PMID:18381287

  4. Ameliorative Effect of Hexane Extract of Phalaris canariensis on High Fat Diet-Induced Obese and Streptozotocin-Induced Diabetic Mice

    Directory of Open Access Journals (Sweden)

    Rosa Martha Perez Gutierrez

    2014-01-01

    Full Text Available Obesity is one of the major factors to increase various disorders like diabetes. The present paper emphasizes study related to the antiobesity effect of Phalaris canariensis seeds hexane extract (Al-H in high-fat diet- (HFD- induced obese CD1 mice and in streptozotocin-induced mild diabetic (MD and severely diabetic (SD mice.AL-H was orally administered to MD and SD mice at a dose of 400 mg/kg once a day for 30 days, and a set of biochemical parameters were studied: glucose, cholesterol, triglycerides, lipid peroxidation, liver and muscle glycogen, ALP, SGOT, SGPT, glucose-6-phosphatase, glucokinase, hexokinase, SOD, CAT, GSH, GPX activities, and the effect on insulin level. HS-H significantly reduced the intake of food and water and body weight loss as well as levels of blood glucose, serum cholesterol, triglyceride, lipoprotein, oxidative stress, showed a protective hepatic effect, and increased HDL-cholesterol, serum insulin in diabetic mice. The mice fed on the high-fat diet and treated with AL-H showed inhibitory activity on the lipid metabolism decreasing body weight and weight of the liver and visceral adipose tissues and cholesterol and triglycerides in the liver. We conclude that AL-H can efficiently reduce serum glucose and inhibit insulin resistance, lipid abnormalities, and oxidative stress in MD and SD mice. Our results demonstrate an antiobesity effect reducing lipid droplet accumulation in the liver, indicating that its therapeutic properties may be due to the interaction plant components soluble in the hexane extract, with any of the multiple targets involved in obesity and diabetes pathogenesis.

  5. Subcellular localization of glycolytic enzymes and characterization of intermediary metabolism of Trypanosoma rangeli.

    Science.gov (United States)

    Rondón-Mercado, Rocío; Acosta, Héctor; Cáceres, Ana J; Quiñones, Wilfredo; Concepción, Juan Luis

    2017-09-01

    Trypanosoma rangeli is a hemoflagellate protist that infects wild and domestic mammals as well as humans in Central and South America. Although this parasite is not pathogenic for human, it is being studied because it shares with Trypanosoma cruzi, the etiological agent of Chagas' disease, biological characteristics, geographic distribution, vectors and vertebrate hosts. Several metabolic studies have been performed with T. cruzi epimastigotes, however little is known about the metabolism of T. rangeli. In this work we present the subcellular distribution of the T. rangeli enzymes responsible for the conversion of glucose to pyruvate, as determined by epifluorescense immunomicroscopy and subcellular fractionation involving either selective membrane permeabilization with digitonin or differential and isopycnic centrifugation. We found that in T. rangeli epimastigotes the first six enzymes of the glycolytic pathway, involved in the conversion of glucose to 1,3-bisphosphoglycerate are located within glycosomes, while the last four steps occur in the cytosol. In contrast with T. cruzi, where three isoenzymes (one cytosolic and two glycosomal) of phosphoglycerate kinase are expressed simultaneously, only one enzyme with this activity is detected in T. rangeli epimastigotes, in the cytosol. Consistent with this latter result, we found enzymes involved in auxiliary pathways to glycolysis needed to maintain adenine nucleotide and redox balances within glycosomes such as phosphoenolpyruvate carboxykinase, malate dehydrogenase, fumarate reductase, pyruvate phosphate dikinase and glycerol-3-phosphate dehydrogenase. Glucokinase, galactokinase and the first enzyme of the pentose-phosphate pathway, glucose-6-phosphate dehydrogenase, were also located inside glycosomes. Furthermore, we demonstrate that T. rangeli epimastigotes growing in LIT medium only consume glucose and do not excrete ammonium; moreover, they are unable to survive in partially-depleted glucose medium. The

  6. Contribution of type 2 diabetes associated loci in the Arabic population from Tunisia: a case-control study

    Directory of Open Access Journals (Sweden)

    Almawi Wassim Y

    2009-04-01

    Full Text Available Abstract Background Candidate gene and genome-wide association studies have both reproducibly identified several common Single Nucleotide Polymorphisms (SNPs that confer type 2 diabetes (T2D risk in European populations. Our aim was to evaluate the contribution to T2D of five of these established T2D-associated loci in the Arabic population from Tunisia. Methods A case-control design comprising 884 type 2 diabetic patients and 513 control subjects living in the East-Center of Tunisia was used to analyze the contribution to T2D of the following SNPs: E23K in KCNJ11/Kir6.2, K121Q in ENPP1, the -30G/A variant in the pancreatic β-cell specific promoter of Glucokinase, rs7903146 in TCF7L2 encoding transcription factor 7-like2, and rs7923837 in HHEX encoding the homeobox, hematopoietically expressed transcription factor. Results TCF7L2-rs7903146 T allele increased susceptibility to T2D (OR = 1.25 [1.06–1.47], P = 0.006 in our study population. This risk was 56% higher among subjects carrying the TT genotype in comparison to those carrying the CC genotype (OR = 1.56 [1.13–2.16], P = 0.002. No allelic or genotypic association with T2D was detected for the other studied polymorphisms. Conclusion In the Tunisian population, TCF7L2-rs7903146 T allele confers an increased risk of developing T2D as previously reported in the European population and many other ethnic groups. In contrast, none of the other tested SNPs that influence T2D risk in the European population was associated with T2D in the Tunisian Arabic population. An insufficient power to detect minor allelic contributions or genetic heterogeneity of T2D between different ethnic groups can explain these findings.

  7. Associations between a polymorphism in the pleiotropic GCKR and Age-related phenotypes: the HALCyon programme.

    Directory of Open Access Journals (Sweden)

    Tamuno Alfred

    Full Text Available The glucokinase regulatory protein encoded by GCKR plays an important role in glucose metabolism and a single nucleotide polymorphism (SNP rs1260326 (P446L in the gene has been associated with several age-related biomarkers, including triglycerides, glucose, insulin and apolipoproteins. However, associations between SNPs in the gene and other ageing phenotypes such as cognitive and physical capability have not been reported.As part of the Healthy Ageing across the Life Course (HALCyon collaborative research programme, men and women from five UK cohorts aged between 44 and 90+ years were genotyped for rs1260326. Meta-analysis was used to pool within-study genotypic associations between the SNP and several age-related phenotypes, including body mass index (BMI, blood lipid levels, lung function, and cognitive and physical capability.We confirm the associations between the minor allele of the SNP and higher triglycerides and lower glucose levels. We also observed a triglyceride-independent association between the minor allele and lower BMI (pooled beta on z-score= -0.04, p-value=0.0001, n=16,251. Furthermore, there was some evidence for gene-environment interactions, including physical activity attenuating the effects on triglycerides. However, no associations were observed with measures of cognitive and physical capability.Findings from middle-aged to older adults confirm associations between rs1260326 GCKR and triglycerides and glucose, suggest possible gene-environment interactions, but do not provide evidence that its relevance extends to cognitive and physical capability.

  8. Associations of common polymorphisms in GCKR with type 2 diabetes and related traits in a Han Chinese population: a case-control study

    Directory of Open Access Journals (Sweden)

    Lu Daru

    2011-05-01

    Full Text Available Abstract Background Several studies have shown that variants in the glucokinase regulatory protein gene (GCKR were associated with type 2 diabetes and dyslipidemia. The purpose of this study was to examine whether tag single nucleotide polymorphisms (SNPs in the GCKR region were associated with type 2 diabetes and related traits in a Han Chinese population and to identify the potential mechanisms underlying these associations. Methods We investigated the association of polymorphisms in the GCKR gene with type 2 diabetes by employing a case-control study design (1118 cases and 1161 controls. Four tag SNPs (rs8179206, rs2293572, rs3817588 and rs780094 with pairwise r2 > 0.8 and minor allele frequency > 0.05 across the GCKR gene and its flanking regions were studied and haplotypes were constructed. Genotyping was performed by matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy using a MassARRAY platform. Results The G alleles of GCKR rs3817588 and rs780094 were associated with an increased risk of type 2 diabetes after adjustment for year of birth, sex and BMI (OR = 1.24, 95% CI 1.08-1.43, p = 0.002 and OR = 1.22, 95% CI 1.07-1.38, p = 0.002, respectively. In the non-diabetic controls, the GG carriers of rs3817588 and rs780094 were nominally associated with a lower plasma triglyceride level compared to the AA carriers after adjustment for year of birth, sex and BMI (p for trend = 0.00004 and 0.03, respectively. Furthermore, the association of rs3817588 with plasma triglyceride level was still significant after correcting for multiple testing. Conclusions The rs3817588 A/G polymorphism of the GCKR gene was associated with type 2 diabetes and plasma triglyceride level in the Han Chinese population.

  9. Inhibition of Anaerobic Phosphate Release by Nitric Oxide in Activated Sludge

    Science.gov (United States)

    Van Niel, E. W. J.; Appeldoorn, K. J.; Zehnder, A. J. B.; Kortstee, G. J. J.

    1998-01-01

    Activated sludge not containing significant numbers of denitrifying, polyphosphate [poly(P)]-accumulating bacteria was grown in a fill-and-draw system and exposed to alternating anaerobic and aerobic periods. During the aerobic period, poly(P) accumulated up to 100 mg of P · g of (dry) weight. When portions of the sludge were incubated anaerobically in the presence of acetate, 80 to 90% of the intracellular poly(P) was degraded and released as orthophosphate. Degradation of poly(P) was mainly catalyzed by the concerted action of polyphosphate:AMP phosphotransferase and adenylate kinase, resulting in ATP formation. In the presence of 0.3 mM nitric oxide (NO) in the liquid-phase release of phosphate, uptake of acetate, formation of poly-β-hydroxybutyrate, utilization of glycogen, and formation of ATP were severely inhibited or completely abolished. In cell extracts of the sludge, adenylate kinase activity was completely inhibited by 0.15 mM NO. The nature of this inhibition was probably noncompetitive, similar to that with hog adenylate kinase. Activated sludge polyphosphate glucokinase was also completely inhibited by 0.15 mM NO. It is concluded that the inhibitory effect of NO on acetate-mediated phosphate release by the sludge used in this study is due to the inhibition of adenylate kinase in the phosphate-releasing organisms. The inhibitory effect of nitrate and nitrite on phosphate release is probably due to their conversion to NO. The lack of any inhibitory effect of NO on adenylate kinase of the poly(P)-accumulating Acinetobacter johnsonii 210A suggests that this type of organism is not involved in the enhanced biological phosphate removal by the sludges used. PMID:9687452

  10. Radiometric assays for glycerol, glucose, and glycogen

    International Nuclear Information System (INIS)

    Bradley, D.C.; Kaslow, H.R.

    1989-01-01

    We have developed radiometric assays for small quantities of glycerol, glucose and glycogen, based on a technique described by Thorner and Paulus for the measurement of glycerokinase activity. In the glycerol assay, glycerol is phosphorylated with [32P]ATP and glycerokinase, residual [32P]ATP is hydrolyzed by heating in acid, and free [32P]phosphate is removed by precipitation with ammonium molybdate and triethylamine. Standard dose-response curves were linear from 50 to 3000 pmol glycerol with less than 3% SD in triplicate measurements. Of the substances tested for interference, only dihydroxyacetone gave a slight false positive signal at high concentration. When used to measure glycerol concentrations in serum and in media from incubated adipose tissue, the radiometric glycerol assay correlated well with a commonly used spectrophotometric assay. The radiometric glucose assay is similar to the glycerol assay, except that glucokinase is used instead of glycerokinase. Dose response was linear from 5 to 3000 pmol glucose with less than 3% SD in triplicate measurements. Glucosamine and N-acetylglucosamine gave false positive signals when equimolar to glucose. When glucose concentrations in serum were measured, the radiometric glucose assay agreed well with hexokinase/glucose-6-phosphate dehydrogenase (H/GDH)-based and glucose oxidase/H2O2-based glucose assays. The radiometric method for glycogen measurement incorporates previously described isolation and digestion techniques, followed by the radiometric assay of free glucose. When used to measure glycogen in mouse epididymal fat pads, the radiometric glycogen assay correlated well with the H/GDH-based glycogen assay. All three radiometric assays offer several practical advantages over spectral assays

  11. Genome sequence of the Fleming strain of Micrococcus luteus, a simple free- living actinobacterium

    Energy Technology Data Exchange (ETDEWEB)

    Young, Michael; Artsatbanov, Vladislav; Beller, Harry R.; Chandra, Govind; Chater, Keith F.; Dover, Lynn G.; Goh, Ee-Been; Kahan, Tamar; Kaprelyants, Arseny S.; Kyrpides, Nikos; Lapidus, Alla; Lowry, Stephen R.; Lykidis, Athanasios; Mahillon, Jacques; Markowitz, Viktor; Mavrommatis, Konstantinos; Mukamolova, Galina V.; Oren, Aharon; Rokem, J. Stefan; Smith, Margaret C. M.; Young, Danielle I.; Greenblatt, Charles L.

    2009-11-01

    Micrococcus luteus (NCTC2665, Fleming strain) has one of the smallest genomes of free living actinobacteria sequenced to date, comprising a single circular chromosome of 2,501,097 bp (G+C content 73%) predicted to encode 2403 proteins. The genome shows extensive synteny with that of the closely related organism, Kocuria rhizophila, from which it was taxonomically separated relatively recently. Despite its small size, the genome harbors 73 IS elements, almost all of which are closely related to elements found in other actinobacteria. An IS element is inserted into the rrs gene of one of only two rrn operons found in M. luteus. The genome encodes only four sigma factors and fourteen response regulators, indicative of adaptation to a rather strict ecological niche (mammalian skin). The high sensitivity of M. luteus to {Beta}-lactam antibiotics may result from the presence of a reduced set of penicillin binding proteins and the absence of a wblC gene, which plays an important role in antibiotic resistance in other actinobacteria. Consistent with the restricted range of compounds it can use as a sole source of carbon for energy and growth, M. luteus has a minimal complement of genes concerned with carbohydrate transport and metabolism and its inability to utilize glucose as a sole carbon source may be due to the apparent absence of a gene encoding glucokinase. Uniquely among characterized bacteria, M. luteus appears to be able to metabolize glycogen only via trehalose, and to make trehalose only via glycogen. It has very few genes associated with secondary metabolism. In contrast to other actinobacteria, M. luteus encodes only one resuscitation-promoting factor (Rpf) required for emergence from dormancy and its complement of other dormancy-related proteins is also much reduced. M. luteus is capable of long-chain alkene biosynthesis, which is of interest for advanced biofuel production; a three gene cluster essential for this metabolism has been identified in the genome.

  12. Ameliorative Effect of Hexane Extract of Phalaris canariensis on High Fat Diet-Induced Obese and Streptozotocin-Induced Diabetic Mice.

    Science.gov (United States)

    Perez Gutierrez, Rosa Martha; Madrigales Ahuatzi, Diana; Horcacitas, Maria Del Carmen; Garcia Baez, Efren; Cruz Victoria, Teresa; Mota-Flores, Jose Maria

    2014-01-01

    Obesity is one of the major factors to increase various disorders like diabetes. The present paper emphasizes study related to the antiobesity effect of Phalaris canariensis seeds hexane extract (Al-H) in high-fat diet- (HFD-) induced obese CD1 mice and in streptozotocin-induced mild diabetic (MD) and severely diabetic (SD) mice.AL-H was orally administered to MD and SD mice at a dose of 400 mg/kg once a day for 30 days, and a set of biochemical parameters were studied: glucose, cholesterol, triglycerides, lipid peroxidation, liver and muscle glycogen, ALP, SGOT, SGPT, glucose-6-phosphatase, glucokinase, hexokinase, SOD, CAT, GSH, GPX activities, and the effect on insulin level. HS-H significantly reduced the intake of food and water and body weight loss as well as levels of blood glucose, serum cholesterol, triglyceride, lipoprotein, oxidative stress, showed a protective hepatic effect, and increased HDL-cholesterol, serum insulin in diabetic mice. The mice fed on the high-fat diet and treated with AL-H showed inhibitory activity on the lipid metabolism decreasing body weight and weight of the liver and visceral adipose tissues and cholesterol and triglycerides in the liver. We conclude that AL-H can efficiently reduce serum glucose and inhibit insulin resistance, lipid abnormalities, and oxidative stress in MD and SD mice. Our results demonstrate an antiobesity effect reducing lipid droplet accumulation in the liver, indicating that its therapeutic properties may be due to the interaction plant components soluble in the hexane extract, with any of the multiple targets involved in obesity and diabetes pathogenesis.

  13. Blocking hexose entry into glycolysis activates alternative metabolic conversion of these sugars and upregulates pentose metabolism in Aspergillus nidulans

    Energy Technology Data Exchange (ETDEWEB)

    Khosravi, Claire; Battaglia, Evy; Kun, Roland S.; Dalhuijsen, Sacha; Visser, Jaap; Aguilar-Pontes, Maria V.; Zhou, Miamiao; Heyman, Heino M.; Kim, Young-Mo; Baker, Scott E.; de Vries, Ronald P.

    2018-03-22

    Background: Plant biomass is the most abundant carbon source for many fungal species. In the biobased industry fungi are used to produce lignocellulolytic enzymes to degrade agricultural waste biomass. Here we evaluated if it would be possible to create an Aspergillus nidulans strain that releases but does not metabolize hexoses from plant biomass. For this purpose, metabolic mutants were generated that were impaired in glycolysis, by using hexokinase (hxkA) and glucokinase (glkA) negative strains. To prevent repression of enzyme production due to the hexose accumulation, strains were generated that combined these mutations with a deletion in creA, the repressor involved in regulating preferential use of different carbon catabolic pathways. Results: Phenotypic analysis revealed reduced growth for the hxkA1 glkA4 mutant on wheat bran. However, hexoses did not accumulate during growth of the mutants on wheat bran, suggesting that glucose metabolism is re-routed towards alternative carbon catabolic pathways. The creAΔ4 mutation in combination with preventing initial phosphorylation in glycolysis resulted in better growth than the hxkA/glkA mutant and an increased expression of pentose catabolic and pentose phosphate pathway genes. This indicates that the reduced ability to use hexoses as carbon sources created a shift towards the pentose fraction of wheat bran as a major carbon source to support growth. Conclusion: Blocking the direct entry of hexoses to glycolysis activates alternative metabolic conversion of these sugars in A. nidulans during growth on plant biomass, but also upregulates conversion of other sugars, such as pentoses.

  14. Ebselen pretreatment attenuates ischemia/reperfusion injury and prevents hyperglycemia by improving hepatic insulin signaling and β-cell survival in gerbils.

    Science.gov (United States)

    Park, S; Kang, S; Kim, D S; Shin, B K; Moon, N R; Daily, J W

    2014-08-01

    Transient carotid artery occlusion causes ischemia/reperfusion (I/R) injury resulting in neuron and pancreatic β-cell death with consequential post-stroke hyperglycemia, which can lead to diabetes and may accelerate the development of Alzheimer's disease. Antioxidants have been shown to protect against the I/R injury and destruction of neurons. However, it is unknown whether the protection against I/R injury extends to the pancreatic β-cells. Therefore, we investigated whether treatment with ebselen, a glutathione peroxidase mimic, prevents neuronal and β-cell death following I/R in gerbils susceptible to stroke. After 28 days post artery occlusion, there was widespread neuronal cell death in the CA1 of the hippocampus and elevated IL-1β and TNF-α levels. Pretreatment with ebselen prevented the death by 56% and attenuated neurological damage (abnormal eyelid drooping, hair bristling, muscle tone, flexor reflex, posture, and walking patterns). Ischemic gerbils also exhibited impaired glucose tolerance and insulin sensitivity which induced post-stroke hyperglycemia associated with decreased β-cell mass due to increased β-cell apoptosis. Ebselen prevented the increased β-cell apoptosis, possibly by decreasing IL-1β and TNF-α in islets. Ischemia also attenuated hepatic insulin signaling, and expression of GLUT2 and glucokinase, whereas ebselen prevented the attenuation and suppressed gluconeogenesis by decreasing PEPCK expression. In conclusion, antioxidant protection by ebselen attenuated I/R injury of neurons and pancreatic β-cells and prevented subsequent impairment of glucose regulation that could lead to diabetes and Alzheimer's disease.

  15. Glucose sensing by GABAergic neurons in the mouse nucleus tractus solitarii

    Science.gov (United States)

    Boychuk, Carie R.; Gyarmati, Peter; Xu, Hong

    2015-01-01

    Changes in blood glucose concentration alter autonomic function in a manner consistent with altered neural activity in brain regions controlling digestive processes, including neurons in the brain stem nucleus tractus solitarii (NTS), which process viscerosensory information. With whole cell or on-cell patch-clamp recordings, responses to elevating glucose concentration from 2.5 to 15 mM were assessed in identified GABAergic NTS neurons in slices from transgenic mice that express EGFP in a subset of GABA neurons. Single-cell real-time RT-PCR was also performed to detect glutamic acid decarboxylase (GAD67) in recorded neurons. In most identified GABA neurons (73%), elevating glucose concentration from 2.5 to 15 mM resulted in either increased (40%) or decreased (33%) neuronal excitability, reflected by altered membrane potential and/or action potential firing. Effects on membrane potential were maintained when action potentials or fast synaptic inputs were blocked, suggesting direct glucose sensing by GABA neurons. Glucose-inhibited GABA neurons were found predominantly in the lateral NTS, whereas glucose-excited cells were mainly in the medial NTS, suggesting regional segregation of responses. Responses were prevented in the presence of glucosamine, a glucokinase (GCK) inhibitor. Depolarizing responses were prevented when KATP channel activity was blocked with tolbutamide. Whereas effects on synaptic input to identified GABAergic neurons were variable in GABA neurons, elevating glucose increased glutamate release subsequent to stimulation of tractus solitarius in unlabeled, unidentified neurons. These results indicate that GABAergic NTS neurons act as GCK-dependent glucose sensors in the vagal complex, providing a means of modulating central autonomic signals when glucose is elevated. PMID:26084907

  16. Association of rs780094 in GCKR with metabolic traits and incident diabetes and cardiovascular disease: the ARIC Study.

    Directory of Open Access Journals (Sweden)

    Mark Bi

    2010-07-01

    Full Text Available The minor T-allele of rs780094 in the glucokinase regulator gene (GCKR associates with a number of metabolic traits including higher triglyceride levels and improved glycemic regulation in study populations of mostly European ancestry. Using data from the Atherosclerosis Risk in Communities (ARIC Study, we sought to replicate these findings, examine them in a large population-based sample of African American study participants, and to investigate independent associations with other metabolic traits in order to determine if variation in GKCR contributes to their observed clustering. In addition, we examined the association of rs780094 with incident diabetes, coronary heart disease (CHD, and stroke over up mean follow-up times of 8, 15, and 15 years, respectively.Race-stratified analyses were conducted among 10,929 white and 3,960 black participants aged 45-64 at baseline assuming an additive genetic model and using linear and logistic regression and Cox proportional hazards models.Previous findings replicated among white participants in multivariable adjusted models: the T-allele of rs780094 was associated with lower fasting glucose (p = 10(-7 and insulin levels (p = 10(-6, lower insulin resistance (HOMA-IR, p = 10(-9, less prevalent diabetes (p = 10(-6, and higher CRP (p = 10(-8, 2-h postprandial glucose (OGTT, p = 10(-6, and triglyceride levels (p = 10(-31. Moreover, the T-allele was independently associated with higher HDL cholesterol levels (p = 0.022, metabolic syndrome prevalence (p = 0.043, and lower beta-cell function measured as HOMA-B (p = 0.011. Among black participants, the T-allele was associated only with higher triglyceride levels (p = 0.004 and lower insulin levels (p = 0.002 and HOMA-IR (p = 0.013. Prospectively, the T-allele was associated with reduced incidence of diabetes (p = 10(-4 among white participants, but not with incidence of CHD or stroke.Our findings indicate rs780094 has independent associations with multiple

  17. Changes in hepatic glucose and lipid metabolism-related parameters in domestic pigeon (Columba livia) during incubation and chick rearing.

    Science.gov (United States)

    Wan, X P; Xie, P; Bu, Z; Zou, X T

    2018-04-01

    This study aimed to evaluate the hepatic glucose and lipid metabolism-related parameters of adult male and female White King pigeons (Columba livia) during incubation and chick rearing. At day 4 (I4), 10 (I10) and 17 (I17) of incubation and day 1 (R1), 7 (R7), 15 (R15) and 25 (R25) of chick rearing, livers were sampled from six pigeons for each sex. Glycogen and fat contents, activities of glycolytic enzymes (hexokinase, HK; 6-phosphofructokinase, 6-PFK), and genes expressions of key enzymes involved in glycolysis (pyruvate kinase, PK; glucokinase, GK), gluconeogenesis (phosphoenolpyruvate carboxykinase cytosolic, PCK1; fructose-1,6-bisphosphatase, FBP1; glucose-6-phosphatase, G6Pase), fatty acid synthesis (fatty acid synthase, FAS; acetyl-CoA carboxylase, ACC) and fatty acid β-oxidation (carnitine palmitoyltransferase 1, CPT1; acyl-CoA 1, ACO) were measured. In male and female pigeon livers, glycogen content and HK activity dramatically increased after I17 and after R1, respectively; expressions of FBP1 and G6Pase genes were maximized at R15; activity of 6-PFK and expressions of PK and CPT1 genes were highest at R7; fat content and expressions of FAS and ACC genes steeply increased from I10 to R1. In females, hepatic expressions of GK and PCK1 genes were greatest at R7 and I17, respectively; however, in males, both of them were maximized at R15. Hepatic expression of ACO gene was significantly enhanced at R1 compared to I17 and R7 in males, whereas it was notably up-regulated at I17 and R7 in females. Furthermore, expressions of PCK1, GK, FAS and ACC genes were in significant relation to fat content in the livers of female pigeons, while fat content in male pigeons was highly correlated with expression of PCK1, ACC, CPT1 and ACO genes. In conclusion, regulations of glucose and lipid metabolic processes were enhanced in parent pigeon livers from terminal phases of incubation to mid phase of chick rearing with sexual effects. © 2017 Blackwell Verlag GmbH.

  18. A single dose of dapagliflozin, an SGLT-2 inhibitor, induces higher glycosuria in GCK- and HNF1A-MODY than in type 2 diabetes mellitus.

    Science.gov (United States)

    Hohendorff, J; Szopa, M; Skupien, J; Kapusta, M; Zapala, B; Platek, T; Mrozinska, S; Parpan, T; Glodzik, W; Ludwig-Galezowska, A; Kiec-Wilk, B; Klupa, T; Malecki, M T

    2017-08-01

    SGLT2 inhibitors are a new class of oral hypoglycemic agents used in type 2 diabetes (T2DM). Their effectiveness in maturity onset diabetes of the young (MODY) is unknown. We aimed to assess the response to a single dose of 10 mg dapagliflozin in patients with Hepatocyte Nuclear Factor 1 Alpha (HNF1A)-MODY, Glucokinase (GCK)-MODY, and type 2 diabetes. We examined 14 HNF1A-MODY, 19 GCK-MODY, and 12 type 2 diabetes patients. All studied individuals received a single morning dose of 10 mg of dapagliflozin added to their current therapy of diabetes. To assess the response to dapagliflozin we analyzed change in urinary glucose to creatinine ratio and serum 1,5-Anhydroglucitol (1,5-AG) level. There were only four patients with positive urine glucose before dapagliflozin administration (one with HNF1A-MODY, two with GCK-MODY, and one with T2DM), whereas after SGLT-2 inhibitor use, glycosuria occurred in all studied participants. Considerable changes in mean glucose to creatinine ratio after dapagliflozin administration were observed in all three groups (20.51 ± 12.08, 23.19 ± 8.10, and 9.84 ± 6.68 mmol/mmol for HNF1A-MODY, GCK-MODY, and T2DM, respectively, p MODY, respectively), but not between the two MODY forms (p = 0.7231). Significant change in serum 1,5-AG was noticed only in T2DM and it was -6.57 ± 7.34 mg/ml (p = 0.04). A single dose of dapagliflozin, an SGLT-2 inhibitor, induces higher glycosuria in GCK- and HNF1A-MODY than in T2DM. Whether flozins are a valid therapeutic option in these forms of MODY requires long-term clinical studies.

  19. Metabolic profiling in Maturity-onset diabetes of the young (MODY) and young onset type 2 diabetes fails to detect robust urinary biomarkers.

    Science.gov (United States)

    Gloyn, Anna L; Faber, Johan H; Malmodin, Daniel; Thanabalasingham, Gaya; Lam, Francis; Ueland, Per Magne; McCarthy, Mark I; Owen, Katharine R; Baunsgaard, Dorrit

    2012-01-01

    It is important to identify patients with Maturity-onset diabetes of the young (MODY) as a molecular diagnosis determines both treatment and prognosis. Genetic testing is currently expensive and many patients are therefore not assessed and are misclassified as having either type 1 or type 2 diabetes. Biomarkers could facilitate the prioritisation of patients for genetic testing. We hypothesised that patients with different underlying genetic aetiologies for their diabetes could have distinct metabolic profiles which may uncover novel biomarkers. The aim of this study was to perform metabolic profiling in urine from patients with MODY due to mutations in the genes encoding glucokinase (GCK) or hepatocyte nuclear factor 1 alpha (HNF1A), type 2 diabetes (T2D) and normoglycaemic control subjects. Urinary metabolic profiling by Nuclear Magnetic Resonance (NMR) and ultra performance liquid chromatography hyphenated to Q-TOF mass spectrometry (UPLC-MS) was performed in a Discovery set of subjects with HNF1A-MODY (n = 14), GCK-MODY (n = 17), T2D (n = 14) and normoglycaemic controls (n = 34). Data were used to build a valid partial least squares discriminate analysis (PLS-DA) model where HNF1A-MODY subjects could be separated from the other diabetes subtypes. No single metabolite contributed significantly to the separation of the patient groups. However, betaine, valine, glycine and glucose were elevated in the urine of HNF1A-MODY subjects compared to the other subgroups. Direct measurements of urinary amino acids and betaine in an extended dataset did not support differences between patients groups. Elevated urinary glucose in HNF1A-MODY is consistent with the previously reported low renal threshold for glucose in this genetic subtype. In conclusion, we report the first metabolic profiling study in monogenic diabetes and show that, despite the distinct biochemical pathways affected, there are unlikely to be robust urinary biomarkers which distinguish monogenic subtypes

  20. Intima-media thickness and endothelial dysfunction in GCK and HNF1A-MODY patients.

    Science.gov (United States)

    Szopa, Magdalena; Osmenda, Grzegorz; Wilk, Grzegorz; Matejko, Bartłomiej; Skupien, Jan; Zapala, Barbara; Młynarski, Wojciech; Guzik, Tomasz; Malecki, Maciej T

    2015-03-01

    Mutations in the glucokinase (GCK) gene, along with hepatocyte nuclear factor 1A (HNF1A) gene mutations, are the most frequent cause of maturity-onset diabetes of the young (MODY). GCK-MODY patients are typically characterized by a moderate fasting hyperglycemia; however, little is known about atherosclerosis and intermediate-related phenotypes in these subjects. To examine carotid artery intima-media thickness (IMT) and endothelial function assessed by brachial artery flow-mediated dilatation (FMD) in GCK gene mutations carriers and HNF1A-MODY. A total of 64 subjects with GCK gene mutations, and 52 HNF1A gene mutation carriers as well as 53 nondiabetic controls were examined. IMT and FMD were assessed by ultrasonography. Appropriate statistical tests were performed to assess differences between the groups, and multivariate linear regression was done for the association with IMT and FMD. The clinical characteristics of all groups were similar with the mean age at examination of 35.1, 41.1, and 39.5 years for GCK, HNF1A and the control group respectively. The highest mean IMT value was in the HNF1A-MODY group: 7.0±1.4 mm, whereas it reached 6.3±1.4 mm in GCK mutation carriers and 6.3±1.3 mm in controls (P=0.008). After adjustment for possible clinical and biochemical cofounders, IMT remained higher in HNF1A-MODY patients as compared with GCK-MODY patients (P=0.02) and controls (P=0.0003). FMD was significantly lower in HNF1A (9.9±4.6%) and GCK-MODY (11.1±4.6%) patients in comparison with controls (13.9±4.7%; P=0.0001). After adjustment, FMD remained lower in HNF1A-MODY (P=0.0005) and GCK-MODY patients (P=0.01) as compared with controls. Both examined MODY groups demonstrated evidence of endothelial dysfunction. In addition, HNF1-MODY patients seem to be more prone to an early atherosclerotic phenotype. © 2015 European Society of Endocrinology.

  1. Metabolic profiling in Maturity-onset diabetes of the young (MODY and young onset type 2 diabetes fails to detect robust urinary biomarkers.

    Directory of Open Access Journals (Sweden)

    Anna L Gloyn

    Full Text Available It is important to identify patients with Maturity-onset diabetes of the young (MODY as a molecular diagnosis determines both treatment and prognosis. Genetic testing is currently expensive and many patients are therefore not assessed and are misclassified as having either type 1 or type 2 diabetes. Biomarkers could facilitate the prioritisation of patients for genetic testing. We hypothesised that patients with different underlying genetic aetiologies for their diabetes could have distinct metabolic profiles which may uncover novel biomarkers. The aim of this study was to perform metabolic profiling in urine from patients with MODY due to mutations in the genes encoding glucokinase (GCK or hepatocyte nuclear factor 1 alpha (HNF1A, type 2 diabetes (T2D and normoglycaemic control subjects. Urinary metabolic profiling by Nuclear Magnetic Resonance (NMR and ultra performance liquid chromatography hyphenated to Q-TOF mass spectrometry (UPLC-MS was performed in a Discovery set of subjects with HNF1A-MODY (n = 14, GCK-MODY (n = 17, T2D (n = 14 and normoglycaemic controls (n = 34. Data were used to build a valid partial least squares discriminate analysis (PLS-DA model where HNF1A-MODY subjects could be separated from the other diabetes subtypes. No single metabolite contributed significantly to the separation of the patient groups. However, betaine, valine, glycine and glucose were elevated in the urine of HNF1A-MODY subjects compared to the other subgroups. Direct measurements of urinary amino acids and betaine in an extended dataset did not support differences between patients groups. Elevated urinary glucose in HNF1A-MODY is consistent with the previously reported low renal threshold for glucose in this genetic subtype. In conclusion, we report the first metabolic profiling study in monogenic diabetes and show that, despite the distinct biochemical pathways affected, there are unlikely to be robust urinary biomarkers which distinguish monogenic

  2. Serum levels of pancreatic stone protein (PSP/reg1A as an indicator of beta-cell apoptosis suggest an increased apoptosis rate in hepatocyte nuclear factor 1 alpha (HNF1A-MODY carriers from the third decade of life onward

    Directory of Open Access Journals (Sweden)

    Bacon Siobhan

    2012-07-01

    Full Text Available Abstract Background Mutations in the transcription factor hepatocyte nuclear factor-1-alpha (HNF1A result in the commonest type of maturity onset diabetes of the young (MODY. HNF1A-MODY carriers have reduced pancreatic beta cell mass, partially due to an increased rate of apoptosis. To date, it has not been possible to determine when apoptosis is occurring in HNF1A-MODY.We have recently demonstrated that beta cell apoptosis stimulates the expression of the pancreatic stone protein/regenerating (PSP/reg gene in surviving neighbour cells, and that PSP/reg1A protein is subsequently secreted from these cells. The objective of this study was to determine whether serum levels of PSP/reg1A are elevated during disease progression in HNF1A-MODY carriers, and whether it may provide information regarding the onset of beta-cell apoptosis. Methods We analysed serum PSP/reg1A levels and correlated with clinical and biochemical parameters in subjects with HNF1A-MODY, glucokinase (GCK-MODY, and type 1 diabetes mellitus. A control group of normoglycaemic subjects was also analysed. Results PSP/reg1A serum levels were significantly elevated in HNF1A-MODY (n = 37 subjects compared to controls (n = 60 (median = 12.50 ng/ml, IQR = 10.61-17.87 ng/ml versus median = 10.72 ng/ml, IQR = 8.94-12.54 ng/ml, p = 0.0008. PSP/reg1A correlated negatively with insulin levels during OGTT, (rho = −0.40, p = 0.02. Interestingly we noted a significant positive correlation of PSP/reg1A with age of the HNF1A-MODY carriers (rho = 0.40 p = 0.02 with an age of 25 years separating carriers with low and high PSP/reg1A levels. Patients with type 1 diabetes mellitus also had elevated serum levels of PSP/reg1A compared to controls, however this was independent of the duration of diabetes. Conclusion Our data suggest that beta cell apoptosis contributes increasingly to the pathophysiology of HNF1A-MODY in patients 25 years and over

  3. Wild-type offspring of heterozygous prolactin receptor-null female mice have maladaptive β-cell responses during pregnancy.

    Science.gov (United States)

    Huang, Carol

    2013-03-01

    Abstract  β-Cell mass increases during pregnancy in adaptation to the insulin resistance of pregnancy. This increase is accompanied by an increase in β-cell proliferation, a process that requires intact prolactin receptor (Prlr) signalling. Previously, it was found that during pregnancy, heterozygous prolactin receptor-null (Prlr(+/-)) mice had lower number of β-cells, lower serum insulin and higher blood glucose levels than wild-type (Prlr(+/+)) mice. An unexpected observation was that the glucose homeostasis of the experimental mouse depends on the genotype of her mother, such that within the Prlr(+/+) group, the Prlr(+/+) offspring derived from Prlr(+/+) mothers (Prlr(+/+(+/+))) had higher β-cell mass and lower blood glucose than those derived from Prlr(+/-) mothers (Prlr(+/+(+/-))). Pathways that are known to regulate β-cell proliferation during pregnancy include insulin receptor substrate-2, Akt, menin, the serotonin synthetic enzyme tryptophan hydroxylase-1, Forkhead box M1 and Forkhead box D3. The aim of the present study was to determine whether dysregulation in these signalling molecules in the islets could explain the maternal effect on the phenotype of the offspring. It was found that the pregnancy-induced increases in insulin receptor substrate-2 and Akt expression in the islets were attenuated in the Prlr(+/+(+/-)) mice in comparison to the Prlr(+/+(+/+)) mice. The expression of Forkhead box D3, which plays a permissive role for β-cell proliferation during pregnancy, was also lower in the Prlr(+/+(+/-)) mice. In contrast, the pregnancy-induced increases in phospho-Jak2, tryptophan hydroxylase-1 and FoxM1, as well as the pregnancy-associated reduction in menin expression, were comparable between the two groups. There was also no difference in expression levels of genes that regulate insulin synthesis and secretion (i.e. glucose transporter 2, glucokinase and pancreatic and duodenal homeobox-1) between these two groups. Taken together, these

  4. Poly(lactic-co-glycolic) acid loaded nano-insulin has greater potentials of combating arsenic induced hyperglycemia in mice: Some novel findings

    Energy Technology Data Exchange (ETDEWEB)

    Samadder, Asmita; Das, Jayeeta; Das, Sreemanti; De, Arnab; Saha, Santu Kumar; Bhattacharyya, Soumya Sundar; Khuda-Bukhsh, Anisur Rahman, E-mail: prof_arkb@yahoo.co.in

    2013-02-15

    Diabetes is a menacing problem, particularly to inhabitants of groundwater arsenic contaminated areas needing new medical approaches. This study examines if PLGA loaded nano-insulin (NIn), administered either intraperitoneally (i.p.) or through oral route, has a greater cost-effective anti-hyperglycemic potential than that of insulin in chronically arsenite-fed hyperglycemic mice. The particle size, morphology and zeta potential of nano-insulin were determined using dynamic light scattering method, scanning electronic and atomic force microscopies. The ability of the nano-insulin (NIn) to cross the blood–brain barrier (BBB) was also checked. Circular dichroic spectroscopic (CD) data of insulin and nano-insulin in presence or absence of arsenic were compared. Several diabetic markers in different groups of experimental and control mice were assessed. The mitochondrial functioning through indices like cytochrome c, pyruvate-kinase, glucokinase, ATP/ADP ratio, mitochondrial membrane potential, cell membrane potential and calcium-ion level was also evaluated. Expressions of the relevant marker proteins and mRNAs like insulin, GLUT2, GLUT4, IRS1, IRS2, UCP2, PI3, PPARγ, CYP1A1, Bcl2, caspase3 and p38 for tracking-down the signaling cascade were also analyzed. Results revealed that i.p.-injected nano-encapsulated-insulin showed better results; NIn, due to its smaller size, faster mobility, site-specific release, could cross BBB and showed positive modulation in mitochondrial signaling cascades and other downstream signaling molecules in reducing arsenic-induced-hyperglycemia. CD data indicated that nano-insulin had less distorted secondary structure as compared with that of insulin in presence of arsenic. Thus, overall analyses revealed that PLGA nano-insulin showed better efficacy in combating arsenite-induced-hyperglycemia than that of insulin and therefore, has greater potentials for use in nano-encapsulated form. - Highlights: ► PLGA encapsulated nano

  5. Poly(lactic-co-glycolic) acid loaded nano-insulin has greater potentials of combating arsenic induced hyperglycemia in mice: Some novel findings

    International Nuclear Information System (INIS)

    Samadder, Asmita; Das, Jayeeta; Das, Sreemanti; De, Arnab; Saha, Santu Kumar; Bhattacharyya, Soumya Sundar; Khuda-Bukhsh, Anisur Rahman

    2013-01-01

    Diabetes is a menacing problem, particularly to inhabitants of groundwater arsenic contaminated areas needing new medical approaches. This study examines if PLGA loaded nano-insulin (NIn), administered either intraperitoneally (i.p.) or through oral route, has a greater cost-effective anti-hyperglycemic potential than that of insulin in chronically arsenite-fed hyperglycemic mice. The particle size, morphology and zeta potential of nano-insulin were determined using dynamic light scattering method, scanning electronic and atomic force microscopies. The ability of the nano-insulin (NIn) to cross the blood–brain barrier (BBB) was also checked. Circular dichroic spectroscopic (CD) data of insulin and nano-insulin in presence or absence of arsenic were compared. Several diabetic markers in different groups of experimental and control mice were assessed. The mitochondrial functioning through indices like cytochrome c, pyruvate-kinase, glucokinase, ATP/ADP ratio, mitochondrial membrane potential, cell membrane potential and calcium-ion level was also evaluated. Expressions of the relevant marker proteins and mRNAs like insulin, GLUT2, GLUT4, IRS1, IRS2, UCP2, PI3, PPARγ, CYP1A1, Bcl2, caspase3 and p38 for tracking-down the signaling cascade were also analyzed. Results revealed that i.p.-injected nano-encapsulated-insulin showed better results; NIn, due to its smaller size, faster mobility, site-specific release, could cross BBB and showed positive modulation in mitochondrial signaling cascades and other downstream signaling molecules in reducing arsenic-induced-hyperglycemia. CD data indicated that nano-insulin had less distorted secondary structure as compared with that of insulin in presence of arsenic. Thus, overall analyses revealed that PLGA nano-insulin showed better efficacy in combating arsenite-induced-hyperglycemia than that of insulin and therefore, has greater potentials for use in nano-encapsulated form. - Highlights: ► PLGA encapsulated nano

  6. Novel anti-diabetic effect of SCM-198 via inhibiting the hepatic NF-κB pathway in db/db mice.

    Science.gov (United States)

    Huang, Hui; Xin, Hong; Liu, Xinhua; Xu, Yajun; Wen, Danyi; Zhang, Yahua; Zhu, Yi Zhun

    2012-04-01

    There are reports of early evidence that suggest the involvement of chronic low-grade inflammation in the pathogenesis of Type 2 diabetes. Thus, substances that have effects in reducing inflammation could be potential drugs for Type 2 diabetes. Leonurine (4-guanidino-n-butyl syringate; SCM-198) is an alkaloid in HL (Herba leonuri), which was reported to possess anti-inflammatory properties. We hypothesize that SCM-198 may have beneficial effects on Type 2 diabetes. In the present study, we attempted to test this hypothesis by evaluating the anti-diabetic effect of SCM-198 and the possible underlying mechanisms of its effects in db/db mice. SCM-198 (50, 100 and 200 mg/kg of body weight), pioglitazone (50 mg/kg of body weight, as a positive control) or 1% CMC-Na (sodium carboxymethylcellulose) were administered to the db/db or db/m mice once daily for 3 weeks. After 3 weeks, SCM-198 (200 mg/kg of body weight) treatment significantly reduced the fasting blood glucose level and increased the plasma insulin concentration in the db/db mice, meanwhile it significantly lowered the plasma TAG (triacylglycerol) concentration and increased the HDL (high-density lipoprotein)-cholesterol concentration. Moreover, the dysregulated transcription of the hepatic glucose metabolic enzymes, including GK (glucokinase), G6Pase (glucose-6-phosphatase) and PEPCK (phosphoenolpyruvate carboxykinase), was recovered by an Akt-dependent pathway. The pro-inflammatory mediators {such as TNFα (tumour necrosis factor α), IL (interleukin)-6, IL-1β, degradation of IκB [inhibitor of NF-κB (nuclear factor-κB)] α and thereafter activation of NF-κB} were reversed by SCM-198 treatment in the db/db mice. The present study provides first evidence that SCM-198 exhibits anti-inflammatory activity and has an ameliorating effect on diabetic symptoms via inhibiting of NF-κB/IKK (IκB kinase) pathway. Consequently, we suggest that SCM-198 may be a prospective agent for prevention and

  7. Serum levels of pancreatic stone protein (PSP)/reg1A as an indicator of beta-cell apoptosis suggest an increased apoptosis rate in hepatocyte nuclear factor 1 alpha (HNF1A-MODY) carriers from the third decade of life onward

    LENUS (Irish Health Repository)

    Bacon, Siobhan

    2012-07-18

    AbstractBackgroundMutations in the transcription factor hepatocyte nuclear factor-1-alpha (HNF1A) result in the commonest type of maturity onset diabetes of the young (MODY). HNF1A-MODY carriers have reduced pancreatic beta cell mass, partially due to an increased rate of apoptosis. To date, it has not been possible to determine when apoptosis is occurring in HNF1A-MODY.We have recently demonstrated that beta cell apoptosis stimulates the expression of the pancreatic stone protein\\/regenerating (PSP\\/reg) gene in surviving neighbour cells, and that PSP\\/reg1A protein is subsequently secreted from these cells. The objective of this study was to determine whether serum levels of PSP\\/reg1A are elevated during disease progression in HNF1A-MODY carriers, and whether it may provide information regarding the onset of beta-cell apoptosis.MethodsWe analysed serum PSP\\/reg1A levels and correlated with clinical and biochemical parameters in subjects with HNF1A-MODY, glucokinase (GCK-MODY), and type 1 diabetes mellitus. A control group of normoglycaemic subjects was also analysed.ResultsPSP\\/reg1A serum levels were significantly elevated in HNF1A-MODY (n = 37) subjects compared to controls (n = 60) (median = 12.50 ng\\/ml, IQR = 10.61-17.87 ng\\/ml versus median = 10.72 ng\\/ml, IQR = 8.94-12.54 ng\\/ml, p = 0.0008). PSP\\/reg1A correlated negatively with insulin levels during OGTT, (rho = −0.40, p = 0.02). Interestingly we noted a significant positive correlation of PSP\\/reg1A with age of the HNF1A-MODY carriers (rho = 0.40 p = 0.02) with an age of 25 years separating carriers with low and high PSP\\/reg1A levels. Patients with type 1 diabetes mellitus also had elevated serum levels of PSP\\/reg1A compared to controls, however this was independent of the duration of diabetes.ConclusionOur data suggest that beta cell apoptosis contributes increasingly to the pathophysiology of HNF1A-MODY in patients 25 years and

  8. One pot synthesis of GDP-mannose by a multi-enzyme cascade for enzymatic assembly of lipid-linked oligosaccharides.

    Science.gov (United States)

    Rexer, Thomas F T; Schildbach, Anna; Klapproth, Jan; Schierhorn, Angelika; Mahour, Reza; Pietzsch, Markus; Rapp, Erdmann; Reichl, Udo

    2018-01-01

    Glycosylation of proteins is a key function of the biosynthetic-secretory pathway in the endoplasmic reticulum (ER) and Golgi apparatus. Glycosylated proteins play a crucial role in cell trafficking and signaling, cell-cell adhesion, blood-group antigenicity, and immune response. In addition, the glycosylation of proteins is an important parameter in the optimization of many glycoprotein-based drugs such as monoclonal antibodies. In vitro glycoengineering of proteins requires glycosyltransferases as well as expensive nucleotide sugars. Here, we present a designed pathway consisting of five enzymes, glucokinase (Glk), phosphomannomutase (ManB), mannose-1-phosphate-guanyltransferase (ManC), inorganic pyrophosphatase (PmPpA), and 1-domain polyphosphate kinase 2 (1D-Ppk2) expressed in E. coli for the cell-free production and regeneration of GDP-mannose from mannose and polyphosphate with catalytic amounts of GDP and ADP. It was shown that GDP-mannose is produced at various conditions, that is pH 7-8, temperature 25-35°C and co-factor concentrations of 5-20 mM MgCl 2 . The maximum reaction rate of GDP-mannose achieved was 2.7 μM/min at 30°C and 10 mM MgCl 2 producing 566 nmol GDP-mannose after a reaction time of 240 min. With respect to the initial GDP concentration (0.8 mM) this is equivalent to a yield of 71%. Additionally, the cascade was coupled to purified, transmembrane-deleted Alg1 (ALG1ΔTM), the first mannosyltransferase in the ER-associated lipid-linked oligosaccharide (LLO) assembly. Thereby, in a one-pot reaction, phytanyl-PP-(GlcNAc) 2 -Man 1 was produced with efficient nucleotide sugar regeneration for the first time. Phytanyl-PP-(GlcNAc) 2 -Man 1 can serve as a substrate for the synthesis of LLO for the cell-free in vitro glycosylation of proteins. A high-performance anion exchange chromatography method with UV and conductivity detection (HPAEC-UV/CD) assay was optimized and validated to determine the enzyme kinetics. The established

  9. One pot synthesis of GDP‐mannose by a multi‐enzyme cascade for enzymatic assembly of lipid‐linked oligosaccharides

    Science.gov (United States)

    Schildbach, Anna; Klapproth, Jan; Schierhorn, Angelika; Mahour, Reza; Pietzsch, Markus; Rapp, Erdmann; Reichl, Udo

    2017-01-01

    Abstract Glycosylation of proteins is a key function of the biosynthetic‐secretory pathway in the endoplasmic reticulum (ER) and Golgi apparatus. Glycosylated proteins play a crucial role in cell trafficking and signaling, cell‐cell adhesion, blood‐group antigenicity, and immune response. In addition, the glycosylation of proteins is an important parameter in the optimization of many glycoprotein‐based drugs such as monoclonal antibodies. In vitro glycoengineering of proteins requires glycosyltransferases as well as expensive nucleotide sugars. Here, we present a designed pathway consisting of five enzymes, glucokinase (Glk), phosphomannomutase (ManB), mannose‐1‐phosphate‐guanyltransferase (ManC), inorganic pyrophosphatase (PmPpA), and 1‐domain polyphosphate kinase 2 (1D‐Ppk2) expressed in E. coli for the cell‐free production and regeneration of GDP‐mannose from mannose and polyphosphate with catalytic amounts of GDP and ADP. It was shown that GDP‐mannose is produced at various conditions, that is pH 7–8, temperature 25–35°C and co‐factor concentrations of 5–20 mM MgCl2. The maximum reaction rate of GDP‐mannose achieved was 2.7 μM/min at 30°C and 10 mM MgCl2 producing 566 nmol GDP‐mannose after a reaction time of 240 min. With respect to the initial GDP concentration (0.8 mM) this is equivalent to a yield of 71%. Additionally, the cascade was coupled to purified, transmembrane‐deleted Alg1 (ALG1ΔTM), the first mannosyltransferase in the ER‐associated lipid‐linked oligosaccharide (LLO) assembly. Thereby, in a one‐pot reaction, phytanyl‐PP‐(GlcNAc)2‐Man1 was produced with efficient nucleotide sugar regeneration for the first time. Phytanyl‐PP‐(GlcNAc)2‐Man1 can serve as a substrate for the synthesis of LLO for the cell‐free in vitro glycosylation of proteins. A high‐performance anion exchange chromatography method with UV and conductivity detection (HPAEC‐UV/CD) assay was optimized and

  10. A genetic screen identifies interferon-α effector genes required to suppress hepatitis C virus replication.

    Science.gov (United States)

    Fusco, Dahlene N; Brisac, Cynthia; John, Sinu P; Huang, Yi-Wen; Chin, Christopher R; Xie, Tiao; Zhao, Hong; Jilg, Nikolaus; Zhang, Leiliang; Chevaliez, Stephane; Wambua, Daniel; Lin, Wenyu; Peng, Lee; Chung, Raymond T; Brass, Abraham L

    2013-06-01

    Hepatitis C virus (HCV) infection is a leading cause of end-stage liver disease. Interferon-α (IFNα) is an important component of anti-HCV therapy; it up-regulates transcription of IFN-stimulated genes, many of which have been investigated for their antiviral effects. However, all of the genes required for the antiviral function of IFNα (IFN effector genes [IEGs]) are not known. IEGs include not only IFN-stimulated genes, but other nontranscriptionally induced genes that are required for the antiviral effect of IFNα. In contrast to candidate approaches based on analyses of messenger RNA (mRNA) expression, identification of IEGs requires a broad functional approach. We performed an unbiased genome-wide small interfering RNA screen to identify IEGs that inhibit HCV. Huh7.5.1 hepatoma cells were transfected with small interfering RNAs incubated with IFNα and then infected with JFH1 HCV. Cells were stained using HCV core antibody, imaged, and analyzed to determine the percent infection. Candidate IEGs detected in the screen were validated and analyzed further. The screen identified 120 previously unreported IEGs. From these, we more fully evaluated the following: asparagine-linked glycosylation 10 homolog (yeast, α-1,2-glucosyltransferase); butyrylcholinesterase; dipeptidyl-peptidase 4 (CD26, adenosine deaminase complexing protein 2); glucokinase (hexokinase 4) regulator; guanylate cyclase 1, soluble, β 3; MYST histone acetyltransferase 1; protein phosphatase 3 (formerly 2B), catalytic subunit, β isoform; peroxisomal proliferator-activated receptor-γ-DBD-interacting protein 1; and solute carrier family 27 (fatty acid transporter), member 2; and demonstrated that they enabled IFNα-mediated suppression of HCV at multiple steps of its life cycle. Expression of these genes had more potent effects against flaviviridae because a subset was required for IFNα to suppress dengue virus but not influenza A virus. In addition, many of the host genes detected in this

  11. A novel fermentation strategy for removing the key inhibitor acetic acid and efficiently utilizing the mixed sugars from lignocellulosic hydrolysates

    Energy Technology Data Exchange (ETDEWEB)

    Mark A. Eiteman PHD; Elliot Altman Phd

    2009-02-11

    As part of preliminary research efforts, we have completed several experiments which demonstrate 'proof of concept.' These experiments addressed the following three questions: (1) Can a synthetic mixed sugar solution of glucose and xylose be efficiently consumed using the multi-organism approach? (2) Can this approach be used to accumulate a model product? (3) Can this approach be applied to the removal of an inhibitor, acetate, selectively from mixtures of xylose and glucose? To answer the question of whether this multi-organism approach can effectively consume synthetic mixed sugar solutions, we first tested substrate-selective uptake using two strains, one unable to consume glucose and one unable to consume xylose. The xylose-selective strain ALS998 has mutations in the three genes involved in glucose uptake, rendering it unable to consume glucose: ptsG codes for the Enzyme IICB{sup Glc} of the phosphotransferase system (PTS) for carbohydrate transport (Postma et al., 1993), manZ codes for the IID{sup Man} domain of the mannose PTS permease (Huber, 1996), glk codes for glucokinase (Curtis and Epstein 1975) We also constructed strain ALS1008 which has a knockout in the xylA gene encoding for xylose isomerase, rendering ALS1008 unable to consume xylose. Two batch experiments and one continuous bioprocess were completed. In the first experiment, each strain was grown separately in a defined medium of 8 g/L xylose and 15 g/L glucose which represented xylose and glucose concentrations that can be generated by actual biomass. In the second experiment, the two strains were grown together in batch in the same defined, mixed-sugar medium. In a third experiment, we grew the strains continuously in a 'chemostat', except that we shifted the concentrations of glucose and xylose periodically to observe how the system would respond. (For example, we shifted the glucose concentration suddenly from 15 g/L to 30 g/L in the feed).

  12. Diet-induced obesity associated with steatosis, oxidative stress, and inflammation in liver.

    Science.gov (United States)

    Peng, Yanhua; Rideout, Drew; Rakita, Steven; Lee, James; Murr, Michel

    2012-01-01

    Obesity induces steatosis and increases oxidative stress, as well as chronic inflammation in the liver. The balance between lipogenesis and lipolysis is disrupted in obese animals. At a cellular level, the changes in metabolic sensors and energy regulators are poorly understood. We hypothesized that diet-induced steatosis increases oxidative stress, inflammation, and changes the metabolic regulators to promote energy storage in mice. The setting was a university-affiliated basic science research laboratory. Four-week-old C57BL mice were fed a high-fat diet (n = 8) or regular chow (n = 8) for 7 weeks. The liver sections were stained for fat content and immunofluorescence. Liver homogenates were used for protein analysis by immunoblotting and mRNA analysis by reverse transcriptase-polymerase chain reaction. The gels were quantified using densitometry P ≤ .05 was considered significant. The high-fat diet upregulated protein kinase-C atypical isoforms ζ and λ and decreased glucose tolerance and the interaction of insulin receptor substrate 2 with phosphoinositide kinase-3. The high-fat diet increased the transcriptional factors liver X receptor (4321 ± 98 versus 2981 ± 80) and carbohydrate response element-binding protein (5132 ± 135 versus 3076 ± 91), the lipogenesis genes fatty acid binding protein 5, stearoyl-co-enzyme A desaturase-1, and acetyl-co-enzyme A carboxylase protein, and fatty acid synthesis. The high-fat diet decreased 5'-adenosine monophosphate-activated protein kinase (2561 ± 78 versus 1765 ± 65), glucokinase-3β (2.214 ± 34 versus 3356 ± 86), and SIRT1 (2015 ± 76 versus 3567 ± 104) and increased tumor necrosis factor-α (3415 ± 112 versus 2042 ± 65), nuclear factor kappa B (5123 ± 201 versus 2562 ± 103), cyclooxygenase-2 (4230 ± 113 versus 2473 ± 98), nicotinamide-adenine dinucleotide phosphate oxidase (3501 ± 106 versus 1600 ± 69) and reactive oxygen species production (all P high-fat diet impairs glucose tolerance and hepatic

  13. Enhancing the Sweetness of Yoghurt through Metabolic Remodeling of Carbohydrate Metabolism in Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus.

    Science.gov (United States)

    Sørensen, Kim I; Curic-Bawden, Mirjana; Junge, Mette P; Janzen, Thomas; Johansen, Eric

    2016-06-15

    Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus are used in the fermentation of milk to produce yoghurt. These species normally metabolize only the glucose moiety of lactose, secreting galactose and producing lactic acid as the main metabolic end product. We used multiple serial selection steps to isolate spontaneous mutants of industrial strains of S. thermophilus and L. delbrueckii subsp. bulgaricus that secreted glucose rather than galactose when utilizing lactose as a carbon source. Sequencing revealed that the S. thermophilus strains had mutations in the galKTEM promoter, the glucokinase gene, and genes encoding elements of the glucose/mannose phosphotransferase system (PTS). These strains metabolize galactose but are unable to phosphorylate glucose internally or via the PTS. The L. delbrueckii subsp. bulgaricus mutants had mutations in genes of the glucose/mannose PTS and in the pyruvate kinase gene. These strains cannot grow on exogenous glucose but are proficient at metabolizing internal glucose released from lactose by β-galactosidase. The resulting strains can be combined to ferment milk, producing yoghurt with no detectable lactose, moderate levels of galactose, and high levels of glucose. Since glucose tastes considerably sweeter than either lactose or galactose, the sweetness of the yoghurt is perceptibly enhanced. These strains were produced without the use of recombinant DNA technology and can be used for the industrial production of yoghurt with enhanced intrinsic sweetness and low residual levels of lactose. Based on a good understanding of the physiology of the lactic acid bacteria Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus, we were able, by selecting spontaneously occurring mutants, to change dramatically the metabolic products secreted into the growth medium. These mutants consume substantially more of the lactose, metabolize some of the galactose, and secrete the remaining galactose

  14. Role of the direct and indirect pathways for glycogen synthesis in rat liver in the postprandial state

    International Nuclear Information System (INIS)

    Huang, M.T.; Veech, R.L.

    1988-01-01

    The pathway for hepatic glycogen synthesis in the postprandial state was studied in meal-fed rats chronically cannulated in the portal vein. Plasma glucose concentration in the portal vein was found to be 4.50 +/- 1.01 mM (mean +/- SE; n = 3) before a meal and 11.54 +/- 0.70 mM (mean +/- SE; n = 4) after a meal in rats meal-fed a diet consisting of 100% commercial rat chow for 7 d. The hepatic-portal difference of plasma glucose concentration showed that liver released glucose in the fasted state and either extracted or released glucose after feeding depending on plasma glucose concentration in the portal vein. The concentration of portal vein glucose at which liver changes from glucose releasing to glucose uptake was 8 mM, the Km of glucokinase. The rate of glycogen synthesis in liver during meal-feeding was found to be approximately 1 mumol glucosyl U/g wet wt/min in rats meal-fed a 50% glucose supplemented chow diet. The relative importance of the direct vs. indirect pathway for the replenishment of hepatic glycogen was determined by the incorporation of [3- 3 H,U- 14 C]glucose into liver glycogen. Labeled glucose was injected into the portal vein at the end of meal-feeding. The ratio of 3 H/ 14 C in the glucosyl units of glycogen was found to be 83-92% of the ratio in liver free glucose six minutes after the injection, indicating that the majority of exogenous glucose incorporated into glycogen did not go through glycolysis. The percent contribution of the direct versus indirect pathway was quantitated from the difference in the relative specific activity (RSA) of [ 3 H] and [ 14 C]-glycogen in rats infused with [3- 3 H,U- 14 C]glucose. No significant difference was found between the RSA of [ 3 H]glycogen and [ 14 C]glycogen, indicating further that the pathway for glycogen synthesis in liver from exogenous glucose is from the direct pathway

  15. PGBR extract ameliorates TNF-α induced insulin resistance in hepatocytes

    Directory of Open Access Journals (Sweden)

    Fu-Chih Chen

    2018-01-01

    Full Text Available Pre-germinated brown rice (PGBR could ameliorate metabolic syndrome, however, not much research estimates the effect of PGBR extract on insulin resistance. The aim of this study is to examine the effects of PGBR extract in TNF-α induced insulin resistance. HepG2 cells, hepatocytes, were cultured in DMEM medium and added with 5 μM insulin or with insulin and 30 ng/ml TNF-α or with insulin, TNF-α and PGBR extract (50, 100, 300 μg/ml. The glucose levels of the medium were decreased by insulin, demonstrating insulin promoted glucose uptake into cell. However, TNF-α inhibited glucose uptake into cells treated with insulin. Moreover, insulin increased the protein expressions of AMP-activated protein kinase (AMPK, insulin receptor substrate-1 (IRS-1, phosphatidylinositol-3-kinase-α (PI3K-α, serine/threonine kinase PI3K-linked protein kinase B (Akt/PKB, glucose transporter-2 (GLUT-2, glucokinase (GCK, peroxisome proliferator activated receptor-α (PPAR-α and PPAR-γ. TNF-α activated p65 and MAPKs (JNK1/2 and ERK1/2 which worsened the expressions of AMPK, IRS-1, PI3K-α, Akt/PKB, GLUT-2, GCK, glycogen synthase kinase-3 (GSK-3, PPAR-α and PPAR-γ. Once this relationship was established, we added PGBR extract to cell with insulin and TNF-α. We found glucose levels of medium were lowered and that the protein expressions of AMPK, IRS-1, PI3K-α, Akt/PKB, GLUT-2, GCK, GSK-3, PPAR-α, PPAR-γ and p65, JNK1/2 were also recovered. In conclusion, this study found that TNF-α inhibited insulin stimulated glucose uptake and aggravated related proteins expressions, suggesting that it might cause insulin resistance. PGBR extract was found to ameliorate this TNF-α induced insulin resistance, suggesting that it might be used in the future to help control insulin resistance.

  16. Molecular mechanisms of action of styrene toxicity in blood plasma and liver.

    Science.gov (United States)

    Niaz, Kamal; Mabqool, Faheem; Khan, Fazlullah; Ismail Hassan, Fatima; Baeeri, Maryam; Navaei-Nigjeh, Mona; Hassani, Shokoufeh; Gholami, Mahdi; Abdollahi, Mohammad

    2017-10-01

    Styrene is an aromatic colorless hydrocarbon available in liquid form and highly volatile. In its pure form, it gives a sweet smell. The primary source of exposure in the environment is from plastic materials, rubber industries, packaging materials, insulations, and fiber glass and carpet industry. Natural sources of styrene include: few metabolites in plants which are transferred through food chain. The current study was designed to evaluate styrene toxicity, including: superoxide dismutase (SOD) and protein carbonyl, oxidative stress, glucose-6-phosphatase (G6Pase), glycogen phosphorylase (GP), and phosphoenolpyruvate carboxykinase (PEPCK) activities, adenosine triphosphate (ATP) to adenosine diphosphate (ADP) ratio, and changes in gene expressions such as glutamate dehydrogenase 1 (GLUD1), glucose transporter 2 (GLUT2), and glucokinase (GCK) in the rat liver tissue. For this purpose, styrene was dissolved in corn oil and was administered via gavage, at doses 250, 500, 1000, 1500, 2000, mg/kg/day per mL and control (corn oil) to each rat with one day off in a week, for 42 days. Plasma SOD and protein carbonyl of plasma were significantly up-regulated in 1000, 1500, and 2000 mg/kg/day styrene administrated groups (P < .001). In addition, styrene caused an increase in lipid peroxidation (LPO) and reactive oxygen species (ROS) in the dose-dependent manners in liver tissue (P < .001). Furthermore, the ferrous reducing antioxidant power (FRAP) and total thiol molecules (TTM) in styrene-treated groups were significantly decreased in liver tissue (P < .001) with increasing doses. In treated rats, styrene significantly increased G6Pase activity (P < .001) and down-regulated GP activity (P < .001) as compared to the control group. The PEPCK activity was significantly raised in a dose-dependent manner (P < .001). The ATP/ADP ratio of live cells was significantly raised by increasing the dose (P < .001). There was significantly an up

  17. Investigating the Synthesis, Structure, and Catalytic Properties of Versatile Gold-Based Nanocatalvsts

    Science.gov (United States)

    Pretzer, Lori A.

    Transition metal nanomaterials are used to catalyze many chemical reactions, including those key to environmental, medicinal, and petrochemical fields. Improving their catalytic properties and lifetime would have significant economic and environmental rewards. Potentially expedient options to make such advancements are to alter the shape, size, or composition of transition metal nanocatalysts. This work investigates the relationships between structure and catalytic properties of synthesized Au, Pd-on-Au, and Au-enzyme model transition metal nanocatalysts. Au and Pd-on-Au nanomaterials were studied due to their wide-spread application and structure-dependent electronic and geometric properties. The goal of this thesis is to contribute design procedures and synthesis methods that enable the preparation of more efficient transition metal nanocatalysts. The influence of the size and composition of Pd-on-Au nanoparticles (NPs) was systematically investigated and each was found to affect the catalyst's surface structure and catalytic properties. The catalytic hydrodechlorination of trichloroethene and reduction of 4-nitrophenol by Pd-on-Au nanoparticles were investigated as these reactions are useful for environmental and pharmaceutical synthesis applications, respectively. Structural characterization revealed that the dispersion and oxidation state of surface Pd atoms are controlled by the Au particle size and concentration of Pd. These structural changes are correlated with observed Pd-on-Au NP activities for both probe reactions, providing new insight into the structure-activity relationships of bimetallic nanocatalysts. Using the structure-dependent electronic properties of Au NPs, a new type of light-triggered biocatalyst was prepared and used to remotely control a model biochemical reaction. This biocatalyst consists of a model thermophilic glucokinase enzyme covalently attached to the surface of Au nanorods. The rod-like shape of the Au nanoparticles made the

  18. Hiperinsulinismo na infância: quando apenas uma dosagem de insulina não é suficiente Hyperinsulinism in infancy and childhood: when an insulin level is not always enough

    Directory of Open Access Journals (Sweden)

    Andrew A. Palladino

    2008-12-01

    átricos, radiologistas, cirurgiões e patologistas, os quais são treinados para diagnosticar, identificar e tratar o hiperinsulinismo.BACKGROUND: Hypoglycemia in infants and children can lead to seizures, developmental delay, and permanent brain damage. Hyperinsulinism (HI is the most common cause of both transient and permanent disorders of hypoglycemia. HI is characterized by dysregulated insulin secretion, which results in persistent mild to severe hypoglycemia. The various forms of HI represent a group of clinically, genetically, and morphologically heterogeneous disorders. CONTENT: Congenital hyperinsulinism is associated with mutations of SUR-1 and Kir6.2, glucokinase, glutamate dehydrogenase, short-chain 3-hydroxyacyl-CoA dehydrogenase, and ectopic expression of SLC16A1 on β-cell plasma membrane. Hyperinsulinism may be associated with perinatal stress such as birth asphyxia, maternal toxemia, prematurity or intrauterine growth retardation, resulting in prolonged neonatal hypoglycemia. Mimickers of hyperinsulinism include neonatal panhypopituitarism, drug-induced hypoglycemia, insulinoma, antiinsulin and insulin-receptor stimulating antibodies, Beckwith-Wiedemann Syndrome, and congenital glycosylation disorders. Laboratory testing for hyperinsulinism may include quantification of blood glucose, plasma insulin, plasma β-hydroxybutyrate, plasma fatty acids, plasma ammonia, plasma acylcarnitine profile and urine organic acids. Genetic testing is available at commercial laboratories for genes known to be associated with hyperinsulinism. Acute insulin response (AIR tests are useful in phenotypic characterization. Imaging and histological tools are also available to diagnose and classify hyperinsulinism. The goal of treatment in infants with hyperinsulinism is to prevent brain damage from hypoglycemia by maintaining plasma glucose levels above 700 mg/l (70 mg/dl through pharmacologic or surgical therapy. SUMMARY: The treatment of hyperinsulinism requires a multidisciplinary approach