Science.gov

Sample records for hepatic glycogen formation

  1. Pathways of hepatic glycogen formation in humans following ingestion of a glucose load in the fed state

    SciTech Connect

    Magnusson, I.; Chandramouli, V.; Schumann, W.C.; Kumaran, K.; Wahren, J.; Landau, B.R.

    1989-06-01

    The relative contributions of the direct and the indirect pathways to hepatic glycogen formation following a glucose load given to humans four hours after a substantial breakfast have been examined. Glucose loads labeled with (6-(/sup 14/)C)glucose were given to six healthy volunteers along with diflunisal (1 g) or acetaminophen (1.5 g), drugs excreted in urine as glucuronides. Distribution of /sup 14/C in the glucose unit of the glucuronide was taken as a measure of the extent to which glucose was deposited directly in liver glycogen (ie, glucose----glucose-6-phosphate----glycogen) rather than indirectly (ie, glucose----C3-compound----glucose-6-phosphate----glycogen). The maximum contribution to glycogen formation by the direct pathway was estimated to be 77% +/- 4%, which is somewhat higher than previous estimates in humans fasted overnight (65% +/- 1%, P less than 0.05). Thus, the indirect pathway of liver glycogen formation following a glucose load is operative in both the overnight fasted and the fed state, although its contribution may be somewhat less in the fed state.

  2. Hepatic glycogen in humans. II. Gluconeogenetic formation after oral and intravenous glucose

    SciTech Connect

    Radziuk, J. )

    1989-08-01

    The amount of glycogen that is formed by gluconeogenetic pathways during glucose loading was quantitated in human subjects. Oral glucose loading was compared with its intravenous administration. Overnight-fasted subjects received a constant infusion or (3-{sup 3}H)glucose and a marker for gluconeogenesis, (U-{sup 14}C)lactate or sodium ({sup 14}C)bicarbonate ({sup 14}C)bicarbonate. An unlabeled glucose load was then administered. Postabsorptively, or after glucose infusion was terminated, a third tracer ((6-{sup 3}H)glucose) infusion was initiated along with a three-step glucagon infusion. Without correcting for background stimulation of ({sup 14}C)glucose production or for dilution of {sup 14}C with citric acid cycle carbon in the oxaloacetate pool, the amount of glycogen mobilized by the glucagon infusion that was produced by gluconeogenesis during oral glucose loading was 2.9 +/- 0.7 g calculated from (U-{sup 14}C)-lactate incorporation and 7.4 +/- 1.3 g calculated using ({sup 14}C)bicarbonate as a gluconeogenetic marker. During intravenous glucose administration the latter measurement also yielded 7.2 +/- 1.1 g. When the two corrections above are applied, the respective quantities became 5.3 +/- 1.7 g for (U-{sup 14}C)lactate as tracer and 14.7 +/- 4.3 and 13.9 +/- 3.6 g for oral and intravenous glucose with ({sup 14}C)bicarbonate as tracer (P less than 0.05, vs. ({sup 14}C)-lactate as tracer). When (2-{sup 14}C)acetate was infused, the same amount of label was incorporated into mobilized glycogen regardless of which route of glucose administration was used. Comparison with previous data also suggests that {sup 14}CO{sub 2} is a potentially useful marker for the gluconeogenetic process in vivo.

  3. Minimal hepatic glucose-6-phosphatase-α activity required to sustain survival and prevent hepatocellular adenoma formation in murine glycogen storage disease type Ia

    PubMed Central

    Lee, Young Mok; Kim, Goo-Young; Pan, Chi-Jiunn; Mansfield, Brian C.; Chou, Janice Y.

    2015-01-01

    Glycogen storage disease type Ia (GSD-Ia), characterized by impaired glucose homeostasis and chronic risk of hepatocellular adenoma (HCA), is caused by a deficiency in glucose-6-phosphatase-α (G6Pase-α or G6PC) activity. In a previous 70–90 week-study, we showed that a recombinant adeno-associated virus (rAAV) vector-mediated gene transfer that restores more than 3% of wild-type hepatic G6Pase-α activity in G6pc−/− mice corrects hepatic G6Pase-α deficiency with no evidence of HCA. We now examine the minimal hepatic G6Pase-α activity required to confer therapeutic efficacy. We show that rAAV-treated G6pc−/− mice expressing 0.2% of wild-type hepatic G6Pase-α activity suffered from frequent hypoglycemic seizures at age 63–65 weeks but mice expressing 0.5–1.3% of wild-type hepatic G6Pase-α activity (AAV-LL mice) sustain 4–6 h of fast and grow normally to age 75–90 weeks. Despite marked increases in hepatic glycogen accumulation, the AAV-LL mice display no evidence of hepatic abnormalities, hepatic steatosis, or HCA. Interprandial glucose homeostasis is maintained by the G6Pase-α/glucose-6-phosphate transporter (G6PT) complex, and G6PT-mediated microsomal G6P uptake is the rate-limiting step in endogenous glucose production. We show that hepatic G6PT activity is increased in AAV-LL mice. These findings are encouraging for clinical studies of G6Pase-α gene-based therapy for GSD-Ia. PMID:26937391

  4. Influence of stevioside on hepatic glycogen levels in fasted rats.

    PubMed

    Hübler, M O; Bracht, A; Kelmer-Bracht, A M

    1994-04-01

    The influence of stevioside, the sweet glycoside of Stevia rebaudiana leaves, on the glycogen levels of fasted rats was investigated. In one set of experiments, single doses of stevioside (200 mumol) or steviol (200 mumol) were given orally to 24-hours fasted rats, either alone or simultaneously with fructose. Under these conditions both stevioside and steviol increased the initial glycogen deposition in the liver. In another set of experiments, stevioside was given to the rats in the drinking water at the beginning of the fasting periods (5:00 p.m.) of 24 and 48 hours. Two different concentrations were given, 1.0 and 2.0 mM. Increased hepatic glycogen levels were found at 48 hours with stevioside (1.0 mM) and at 24 hours with stevioside (2.0 mM). Steviol had no effect on hepatic glycogen levels when given in the drinking water. It can be concluded that stevioside exerts a stimulatory action on hepatic glycogen synthesis under gluconeogenic conditions. PMID:8042003

  5. Hepatic Glycogen Supercompensation Activates AMP-Activated Protein Kinase, Impairs Insulin Signaling, and Reduces Glycogen Deposition in the Liver

    PubMed Central

    Winnick, Jason J.; An, Zhibo; Ramnanan, Christopher J.; Smith, Marta; Irimia, Jose M.; Neal, Doss W.; Moore, Mary Courtney; Roach, Peter J.; Cherrington, Alan D.

    2011-01-01

    OBJECTIVE The objective of this study was to determine how increasing the hepatic glycogen content would affect the liver’s ability to take up and metabolize glucose. RESEARCH DESIGN AND METHODS During the first 4 h of the study, liver glycogen deposition was stimulated by intraportal fructose infusion in the presence of hyperglycemic-normoinsulinemia. This was followed by a 2-h hyperglycemic-normoinsulinemic control period, during which the fructose infusion was stopped, and a 2-h experimental period in which net hepatic glucose uptake (NHGU) and disposition (glycogen, lactate, and CO2) were measured in the absence of fructose but in the presence of a hyperglycemic-hyperinsulinemic challenge including portal vein glucose infusion. RESULTS Fructose infusion increased net hepatic glycogen synthesis (0.7 ± 0.5 vs. 6.4 ± 0.4 mg/kg/min; P < 0.001), causing a large difference in hepatic glycogen content (62 ± 9 vs. 100 ± 3 mg/g; P < 0.001). Hepatic glycogen supercompensation (fructose infusion group) did not alter NHGU, but it reduced the percent of NHGU directed to glycogen (79 ± 4 vs. 55 ± 6; P < 0.01) and increased the percent directed to lactate (12 ± 3 vs. 29 ± 5; P = 0.01) and oxidation (9 ± 3 vs. 16 ± 3; P = NS). This change was associated with increased AMP-activated protein kinase phosphorylation, diminished insulin signaling, and a shift in glycogenic enzyme activity toward a state discouraging glycogen accumulation. CONCLUSIONS These data indicate that increases in hepatic glycogen can generate a state of hepatic insulin resistance, which is characterized by impaired glycogen synthesis despite preserved NHGU. PMID:21270252

  6. Familial nephropathy associated with hepatic type of glycogen storage disease.

    PubMed

    Sonobe, H; Ogawa, K; Takahashi, I

    1976-11-01

    The female patient was diagnosed as having Von Gierke's disease at 14 years of age, based on clinical manifestations, laboratory examination and liver biopsy. At 19 years of age she had uremia and died from its deterioration at 24 years of age. The parents were consanguineous, and a 27-year-old sister is presently hospitalized for renal insufficiency with hepatomegaly. On autopsy, the patient's kidneys were highly contracted and contained a number of small cysts, mainly in the medulla. Histological examination indicated periglomerular fibrosis, glomerular hyalinization, tubular atrophy or cystic dilatation and intersitial fibrosis with round cell infiltration. These findings correspond to Fanconi's familial juvenile nephronophthisis, except for age. The liver was markedly enlarged and indicated severe, glycogen deposits, but the kidney did not contain glycogen deposits. It can, therefore, be presumed that the renal lesions were not a secondary consequence of long-term glycogen deposits but that renal and hepatic lesions were associated with each other. PMID:1070908

  7. Quantitative comparison of pathways of hepatic glycogen repletion in fed and fasted humans

    SciTech Connect

    Shulman, G.I.; Cline, G.; Schumann, W.C.; Chandramouli, V.; Kumaran, K.; Landau, B.R. )

    1990-09-01

    The effect of fasting vs. refeeding on hepatic glycogen repletion by the direct pathway, i.e., glucose----glucose 6-phosphate (G-6-P)----glycogen, was determined. Acetaminophen was administered during an infusion of glucose labeled with (1-13C)- and (6-14C)glucose into four healthy volunteers after an overnight fast and into the same subjects 4 h after breakfast. 13C enrichments in C-1 and C-6 of glucose formed from urinary acetaminophen glucuronide compared with enrichments in C-1 and C-6 of plasma glucose provided an estimate of glycogen formation by the direct pathway. The specific activity of glucose from the glucuronide compared with the specific activity of the plasma glucose, along with the percentages of 14C in C-1 and C-6 of the glucose from the glucuronide, also provided an estimate of the amount of glycogen formed by the direct pathway. The estimates were similar. Those from (6-14C)glucose would have been higher than from (1-13C)glucose if the pentose cycle contribution to overall glucose utilization had been significant. After an overnight fast, during the last hour of infusion, 49 +/- 3% of the glycogen formed was formed via the direct pathway. After breakfast, at similar plasma glucose and insulin concentrations, the percentage increased to 69 +/- 7% (P less than 0.02). Thus the contributions of the pathways to hepatic glycogen formation depend on the dietary state of the individual. For a dietary regimen in which individuals consume multiple meals per day containing at least a moderate amount of carbohydrates most glycogen synthesis occurs by the direct pathway.

  8. Hepatic glycogen can regulate hypoglycemic counterregulation via a liver-brain axis.

    PubMed

    Winnick, Jason J; Kraft, Guillaume; Gregory, Justin M; Edgerton, Dale S; Williams, Phillip; Hajizadeh, Ian A; Kamal, Maahum Z; Smith, Marta; Farmer, Ben; Scott, Melanie; Neal, Doss; Donahue, E Patrick; Allen, Eric; Cherrington, Alan D

    2016-06-01

    Liver glycogen is important for the counterregulation of hypoglycemia and is reduced in individuals with type 1 diabetes (T1D). Here, we examined the effect of varying hepatic glycogen content on the counterregulatory response to low blood sugar in dogs. During the first 4 hours of each study, hepatic glycogen was increased by augmenting hepatic glucose uptake using hyperglycemia and a low-dose intraportal fructose infusion. After hepatic glycogen levels were increased, animals underwent a 2-hour control period with no fructose infusion followed by a 2-hour hyperinsulinemic/hypoglycemic clamp. Compared with control treatment, fructose infusion caused a large increase in liver glycogen that markedly elevated the response of epinephrine and glucagon to a given hypoglycemia and increased net hepatic glucose output (NHGO). Moreover, prior denervation of the liver abolished the improved counterregulatory responses that resulted from increased liver glycogen content. When hepatic glycogen content was lowered, glucagon and NHGO responses to insulin-induced hypoglycemia were reduced. We conclude that there is a liver-brain counterregulatory axis that is responsive to liver glycogen content. It remains to be determined whether the risk of iatrogenic hypoglycemia in T1D humans could be lessened by targeting metabolic pathway(s) associated with hepatic glycogen repletion. PMID:27140398

  9. Hepatic glycogen can regulate hypoglycemic counterregulation via a liver-brain axis

    PubMed Central

    Kraft, Guillaume; Williams, Phillip; Hajizadeh, Ian A.; Kamal, Maahum Z.; Smith, Marta; Farmer, Ben; Scott, Melanie; Neal, Doss; Donahue, E. Patrick; Allen, Eric; Cherrington, Alan D.

    2016-01-01

    Liver glycogen is important for the counterregulation of hypoglycemia and is reduced in individuals with type 1 diabetes (T1D). Here, we examined the effect of varying hepatic glycogen content on the counterregulatory response to low blood sugar in dogs. During the first 4 hours of each study, hepatic glycogen was increased by augmenting hepatic glucose uptake using hyperglycemia and a low-dose intraportal fructose infusion. After hepatic glycogen levels were increased, animals underwent a 2-hour control period with no fructose infusion followed by a 2-hour hyperinsulinemic/hypoglycemic clamp. Compared with control treatment, fructose infusion caused a large increase in liver glycogen that markedly elevated the response of epinephrine and glucagon to a given hypoglycemia and increased net hepatic glucose output (NHGO). Moreover, prior denervation of the liver abolished the improved counterregulatory responses that resulted from increased liver glycogen content. When hepatic glycogen content was lowered, glucagon and NHGO responses to insulin-induced hypoglycemia were reduced. We conclude that there is a liver-brain counterregulatory axis that is responsive to liver glycogen content. It remains to be determined whether the risk of iatrogenic hypoglycemia in T1D humans could be lessened by targeting metabolic pathway(s) associated with hepatic glycogen repletion. PMID:27140398

  10. Chronic ethanol consumption disrupts diurnal rhythms of hepatic glycogen metabolism in mice

    PubMed Central

    Udoh, Uduak S.; Swain, Telisha M.; Filiano, Ashley N.; Gamble, Karen L.; Young, Martin E.

    2015-01-01

    Chronic ethanol consumption has been shown to significantly decrease hepatic glycogen content; however, the mechanisms responsible for this adverse metabolic effect are unknown. In this study, we examined the impact chronic ethanol consumption has on time-of-day-dependent oscillations (rhythms) in glycogen metabolism processes in the liver. For this, male C57BL/6J mice were fed either a control or ethanol-containing liquid diet for 5 wk, and livers were collected every 4 h for 24 h and analyzed for changes in various genes and proteins involved in hepatic glycogen metabolism. Glycogen displayed a robust diurnal rhythm in the livers of mice fed the control diet, with the peak occurring during the active (dark) period of the day. The diurnal glycogen rhythm was significantly altered in livers of ethanol-fed mice, with the glycogen peak shifted into the inactive (light) period and the overall content of glycogen decreased compared with controls. Chronic ethanol consumption further disrupted diurnal rhythms in gene expression (glycogen synthase 1 and 2, glycogenin, glucokinase, protein targeting to glycogen, and pyruvate kinase), total and phosphorylated glycogen synthase protein, and enzyme activities of glycogen synthase and glycogen phosphorylase, the rate-limiting enzymes of glycogen metabolism. In summary, these results show for the first time that chronic ethanol consumption disrupts diurnal rhythms in hepatic glycogen metabolism at the gene and protein level. Chronic ethanol-induced disruption in these daily rhythms likely contributes to glycogen depletion and disruption of hepatic energy homeostasis, a recognized risk factor in the etiology of alcoholic liver disease. PMID:25857999

  11. Interleukin 6 stimulates hepatic glucose release from prelabeled glycogen pools

    SciTech Connect

    Ritchie, D.G. )

    1990-01-01

    Cytokines, derived from a wide variety of cell types, are now believed to initiate many of the physiological responses accompanying the inflammatory phase that follows either Gram-negative septicemia or thermal injury. Because hypoglycemia (after endotoxic challenge) and hyperglycemia (after thermal injury) represent well-characterized responses to these injuries, we sought to determine whether hepatic glycogen metabolism could be altered by specific cytokines. Cultured adult rat hepatocytes were prelabeled with ({sup 14}C)glucose for 24 h, a procedure that resulted in the labeling of hepatic glycogen pools that subsequently could be depleted (with concomitant ({sup 14}C)glucose release) by either glucagon or norepinephrine. After the addition of a highly concentrated human monocyte-conditioned medium (MCM) or various cytokines to these prelabeled cells, ({sup 14}C)glucose release was stimulated by MCM and recombinant human interleukin 6 (IL-6) but was not stimulated by other cytokines tested. Furthermore, only antisera to IL-6 were capable of reducing the glucose-releasing factor activity found in MCM. These data therefore suggest a novel glucoregulatory role for IL-6.

  12. Hepatic glycogen synthesis in the fetal mouse: An ultrastructural, morphometric, and autoradiographic investigation of the relationship between the smooth endoplasmic reticulum and glycogen

    SciTech Connect

    Breslin, J.S.

    1989-01-01

    Fetal rodent hepatocytes undergo a rapid and significant accumulation of glycogen prior to birth. The distinct association of the smooth endoplasmic reticulum (SER) with glycogen during glycogen synthesis documented in the adult hepatocyte has not been clearly demonstrated in the fetus. The experiments described in this dissertation tested the hypothesis that SER is present and functions in the synthesis of fetal hepatic glycogen. Biochemical analysis, light microscopic (LM) histochemistry and electron microscope (EM) morphometry demonstrated that fetal hepatic glycogen synthesis began on day 15, with maximum accumulation occurring between days 17-19. Glycogen accumulation began in a small population of cells. Both the number of cells containing glycogen and the quantity of glycogen per cell increased as glycogen accumulated. Smooth endoplasmic reticulum (SER) was observed on day 14 of gestation and throughout fetal hepatic glycogen synthesis, primarily as dilated ribosome-free terminal extensions of rough endoplasmic reticulum (RER), frequently associated with glycogen. SER was in close proximity to isolated particles of glycogen and at the periphery of large compact glycogen deposits. Morphometry demonstrated that the membrane surface of SER in the average fetal hepatocyte increased as glycogen accumulated through day 18 and dropped significantly as glycogen levels peaked on day 19. Parallel alterations in RER membrane surface, indicated overall increases in ER membrane surface. Autoradiography following administration of {sup 3}H-galactose demonstrated that newly synthesized glycogen was deposited near profiles of SER at day 16 and at day 18; however, at day 18 the majority of label was uniformly distributed over glycogen remote from profiles of SER.

  13. Substrate-induced Nuclear Export and Peripheral Compartmentalization of Hepatic Glucokinase Correlates with Glycogen Deposition

    PubMed Central

    Shiota, Masa; Knobel, Susan M.; Piston, David W.; Cherrington, Alan D.; Magnuson, Mark A.

    2001-01-01

    Hepatic glucokinase (GK) is acutely regulated by binding to its nuclear-anchored regulatory protein (GKRP). Although GK release by GKRP is tightly coupled to the rate of glycogen synthesis, the nature of this association is obscure. To gain insight into this coupling mechanism under physiological stimulating conditions in primary rat hepatocytes, we analyzed the subcellular distribution of GK and GKRP with immunofluorescence, and glycogen deposition with glycogen cytochemical fluorescence, using confocal microscopyand quantitative image analysis. Following stimulation, a fraction of the GK signal translocated from the nucleus to the cytoplasm. The reduction in the nuclear to cytoplasmic ratio of GK, an index of nuclear export, correlated with a >50% increase in glycogen cytochemical fluorescence over a 60min stimulation period. Furthermore, glycogen accumulation was initially deposited in a peripheral pattern in hepatocytes similar to that of GK. These data suggest that a compartmentalization exists of both active GK and the initial sites of glycogen deposition at the hepatocyte surface. PMID:12369705

  14. Investigation and management of the hepatic glycogen storage diseases

    PubMed Central

    2015-01-01

    The glycogen storage diseases (GSD) comprise a group of disorders that involve the disruption of metabolism of glycogen. Glycogen is stored in various organs including skeletal muscle, the kidneys and liver. The liver stores glycogen to supply the rest of the body with glucose when required. Therefore, disruption of this process can lead to hypoglycaemia. If glycogen is not broken down effectively, this can lead to hepatomegaly. Glycogen synthase deficiency leads to impaired glycogen synthesis and consequently the liver is small. Glycogen brancher deficiency can lead to abnormal glycogen being stored in the liver leading to a quite different disorder of progressive liver dysfunction. Understanding the physiology of GSD I, III, VI and IX guides dietary treatments and the provision of appropriate amounts and types of carbohydrates. There has been recent re-emergence in the literature of the use of ketones in therapy, either in the form of the salt D,L-3-hydroxybutyrate or medium chain triglyceride (MCT). High protein diets have also been advocated. Alternative waxy maize based starches seem to show promising early data of efficacy. There are many complications of each of these disorders and they need to be prospectively surveyed and managed. Liver and kidney transplantation is still indicated in severe refractory disease. PMID:26835382

  15. Investigation and management of the hepatic glycogen storage diseases.

    PubMed

    Bhattacharya, Kaustuv

    2015-07-01

    The glycogen storage diseases (GSD) comprise a group of disorders that involve the disruption of metabolism of glycogen. Glycogen is stored in various organs including skeletal muscle, the kidneys and liver. The liver stores glycogen to supply the rest of the body with glucose when required. Therefore, disruption of this process can lead to hypoglycaemia. If glycogen is not broken down effectively, this can lead to hepatomegaly. Glycogen synthase deficiency leads to impaired glycogen synthesis and consequently the liver is small. Glycogen brancher deficiency can lead to abnormal glycogen being stored in the liver leading to a quite different disorder of progressive liver dysfunction. Understanding the physiology of GSD I, III, VI and IX guides dietary treatments and the provision of appropriate amounts and types of carbohydrates. There has been recent re-emergence in the literature of the use of ketones in therapy, either in the form of the salt D,L-3-hydroxybutyrate or medium chain triglyceride (MCT). High protein diets have also been advocated. Alternative waxy maize based starches seem to show promising early data of efficacy. There are many complications of each of these disorders and they need to be prospectively surveyed and managed. Liver and kidney transplantation is still indicated in severe refractory disease. PMID:26835382

  16. Ultrasonographic features of hepatic adenomas in type I glycogen storage disease.

    PubMed

    Bowerman, R A; Samuels, B I; Silver, T M

    1983-02-01

    Focal hepatic masses were delineated by ultrasonography in three of five patients with type I glycogen storage disease (von Gierke's disease). Small hepatic adenomas were visualized as solitary or multiple hyperechoic solid lesions within enlarged, abnormally echogenic livers of increased attenuation. Larger adenomas were heterogeneous, with hypoechoic foci presumed to be secondary to necrosis, hemorrhage, or both. A previously unreported ultrasonographic finding is the markedly enhanced sound transmission identified deep to these solid tumors. PMID:6302304

  17. Hepatic glycogen deposition in a patient with anorexia nervosa and persistently abnormal transaminase levels.

    PubMed

    Kransdorf, Lisa N; Millstine, Denise; Smith, Maxwell L; Aqel, Bashar A

    2016-04-01

    Anorexia nervosa and other eating disorders characterized by calorie restriction have been associated with a variety of hepatic abnormalities. Fatty steatosis has been described in eating disorder patients. We report the rare finding of glycogen accumulation in the liver in a patient with anorexia nervosa, which to our knowledge is only the second such case reported in the literature. This case highlights the importance of monitoring for liver abnormalities in patients with restrictive eating disorders. PMID:26066296

  18. Pregnancy and pentobarbital anaesthesia modify hepatic synthesis of acylglycerol glycerol and glycogen from gluconeogenic precursors during fasting in rats.

    PubMed

    Zorzano, A; Herrera, E

    1988-12-01

    1. Incorporation of gluconeogenic precursors into blood glucose and hepatic glycogen and acylglycerol glycerol was examined in 24 h-fasted virgin rats by using a flooding procedure for substrate administration. At 10 min after their intravenous injection, the conversion of alanine or glycerol into liver glycogen or acylglycerol glycerol was proportional to glucose synthesis. 2. In 24 h-fasted 21-day-pregnant rats, the incorporation of alanine and glycerol into hepatic acylglycerol glycerol was markedly enhanced compared with the control group. In addition, during fasting at late pregnancy, the proportion of substrates directed to acylglycerol glycerol as compared with the fraction incorporated into glucose was augmented. 3. In pentobarbital-treated fasted rats, the incorporation of both alanine and pyruvate into circulating glucose and into hepatic glycogen and acylglycerol glycerol was increased. Pentobarbital treatment increased the proportion of substrates incorporated into liver glycogen, compared with the fraction appearing in circulating glucose. These changes were concomitant with a marked accumulation of glycogen. 4. The data indicate that, during fasting, gluconeogenesis provides glucose as well as hepatic glycogen and acylglycerol glycerol, independently of whether the substrates enter gluconeogenesis at the level of pyruvate or dihydroxyacetone phosphate. PMID:3223926

  19. Beta-endorphin infusion during exercise in rats does not alter hepatic or muscle glycogen.

    PubMed

    Jamurtas, A Z; Goldfarb, A H; Chung, S C; Hegde, S; Marino, C; Fatouros, I G

    2001-12-01

    The aim of this study was to determine whether beta-endorphin infusion influences liver or muscle glycogen concentration during exercise. Thirty-two rats (Harlan Co., IN, USA) with a body mass of 265-290 g were assigned at random to four groups, each of eight rats: (1) beta-endorphin infusion for 90 min at rest; (2) beta-endorphin infusion for 90 min while running on a rodent treadmill at 22 m x min(-1) and 0% grade; (3) saline infusion (0.9% NaCl) for 90 min at rest; and (4) saline infusion for 90 min while running on a rodent treadmill at 22 m x min(-1) and 0% grade. Beta-endorphin infusion elevated plasma beta-endorphin concentration by 2.5-fold at rest compared with saline infusion at rest, and by two-fold after exercise compared with saline infusion after exercise. Beta-endorphin infusion attenuated exercise-induced glucose concentration but did not alter the fasting hepatic glycogen concentration at rest or after exercise compared with saline infusion. Fasting hepatic glycogen decreased significantly as a result of 90 min of exercise independent of treatment. Deep intermedius muscle glycogen concentration at rest was similar after 90 min of both beta-endorphin and saline infusion and decreased significantly as a result of 90 min of exercise independent of treatment. Our results suggest that liver and muscle glycogenolysis is not responsible for the differences in plasma glucose with beta-endorphin infusion during exercise. PMID:11820687

  20. Increased Laforin and Laforin Binding to Glycogen Underlie Lafora Body Formation in Malin-deficient Lafora Disease*

    PubMed Central

    Tiberia, Erica; Turnbull, Julie; Wang, Tony; Ruggieri, Alessandra; Zhao, Xiao-Chu; Pencea, Nela; Israelian, Johan; Wang, Yin; Ackerley, Cameron A.; Wang, Peixiang; Liu, Yan; Minassian, Berge A.

    2012-01-01

    The solubility of glycogen, essential to its metabolism, is a property of its shape, a sphere generated through extensive branching during synthesis. Lafora disease (LD) is a severe teenage-onset neurodegenerative epilepsy and results from multiorgan accumulations, termed Lafora bodies (LB), of abnormally structured aggregation-prone and digestion-resistant glycogen. LD is caused by loss-of-function mutations in the EPM2A or EPM2B gene, encoding the interacting laforin phosphatase and malin E3 ubiquitin ligase enzymes, respectively. The substrate and function of malin are unknown; an early counterintuitive observation in cell culture experiments that it targets laforin to proteasomal degradation was not pursued until now. The substrate and function of laforin have recently been elucidated. Laforin dephosphorylates glycogen during synthesis, without which phosphate ions interfere with and distort glycogen construction, leading to LB. We hypothesized that laforin in excess or not removed following its action on glycogen also interferes with glycogen formation. We show in malin-deficient mice that the absence of malin results in massively increased laforin preceding the appearance of LB and that laforin gradually accumulates in glycogen, which corresponds to progressive LB generation. We show that increasing the amounts of laforin in cell culture causes LB formation and that this occurs only with glycogen binding-competent laforin. In summary, malin deficiency causes increased laforin, increased laforin binding to glycogen, and LB formation. Furthermore, increased levels of laforin, when it can bind glycogen, causes LB. We conclude that malin functions to regulate laforin and that malin deficiency at least in part causes LB and LD through increased laforin binding to glycogen. PMID:22669944

  1. Complete Normalization of Hepatic G6PC Deficiency in Murine Glycogen Storage Disease Type Ia Using Gene Therapy

    PubMed Central

    Yiu, Wai Han; Lee, Young Mok; Peng, Wen-Tao; Pan, Chi-Jiunn; Mead, Paul A; Mansfield, Brian C; Chou, Janice Y

    2010-01-01

    Glycogen storage disease type Ia (GSD-Ia) patients deficient in glucose-6-phosphatase-α (G6Pase-α or G6PC) manifest disturbed glucose homeostasis. We examined the efficacy of liver G6Pase-α delivery mediated by AAV-GPE, an adeno-associated virus (AAV) serotype 8 vector expressing human G6Pase-α directed by the human G6PC promoter/enhancer (GPE), and compared it to AAV-CBA, that directed murine G6Pase-α expression using a hybrid chicken β-actin (CBA) promoter/cytomegalovirus (CMV) enhancer. The AAV-GPE directed hepatic G6Pase-α expression in the infused G6pc−/− mice declined 12-fold from age 2 to 6 weeks but stabilized at wild-type levels from age 6 to 24 weeks. In contrast, the expression directed by AAV-CBA declined 95-fold over 24 weeks, demonstrating that the GPE is more effective in directing persistent in vivo hepatic transgene expression. We further show that the rapid decline in transgene expression directed by AAV-CBA results from an inflammatory immune response elicited by the AAV-CBA vector. The AAV-GPE-treated G6pc−/− mice exhibit normal levels of blood glucose, blood metabolites, hepatic glycogen, and hepatic fat. Moreover, the mice maintained normal blood glucose levels even after 6 hours of fasting. The complete normalization of hepatic G6Pase-α deficiency by the G6PC promoter/enhancer holds promise for the future of gene therapy in human GSD-Ia patients. PMID:20389290

  2. Lobular and cellular patterns of early hepatic glycogen deposition in the rat as observed by light and electron microscopic radioautography after injection of /sup 3/H-galactose

    SciTech Connect

    Michaels, J.E.; Hung, J.T.; Garfield, S.A.; Cardell, R.R. Jr.

    1984-05-01

    Very low hepatic glycogen levels are achieved by overnight fasting of adrenalectomized (ADX) rats. Subsequent injection of dexamethasone (DEX), a synthetic glucocorticoid, stimulates marked increases in glycogen synthesis. Using this system and injecting /sup 3/H-galactose as a glycogen precursor 1 hr prior to sacrifice, the intralobular and intracellular patterns of labeled glycogen deposition were studied by light (LM) and electron (EM) microscopic radioautography. LM radioautography revealed that 1 hr after DEX treatment, labeling patterns for both periportal and centrilobular hepatocytes resembled those in rats with no DEX treatment: 18% of the hepatocytes were unlabeled, and 82% showed light labeling. Two hours after treatment with DEX, 14% of the hepatocytes remained unlabeled, and 78% were lightly labeled; however, 8% of the cells, located randomly throughout the lobule, were intensely labeled. An increased number of heavily labeled cells (26%) appeared 3 hr after DEX treatment; and by 5 hr 91% of the hepatocytes were intensely labeled. Label over the periportal cells at this time was aggregated, whereas centrilobular cells displayed dispersed label. EM radioautographs showed that 2 to 3 hr after DEX injection initial labeling of hepatocytes, regardless of their intralobular location, occurred over foci of smooth endoplasmic reticulum (SER) and small electron-dense particles of presumptive glycogen, and in areas of SER and distinct glycogen particles. After 5 hrs of treatment with DEX, the intracellular distribution of label reflected the glycogen patterns characteristic of periportal or centrilobular regions.

  3. Glycogen metabolism in humans.

    PubMed

    Adeva-Andany, María M; González-Lucán, Manuel; Donapetry-García, Cristóbal; Fernández-Fernández, Carlos; Ameneiros-Rodríguez, Eva

    2016-06-01

    In the human body, glycogen is a branched polymer of glucose stored mainly in the liver and the skeletal muscle that supplies glucose to the blood stream during fasting periods and to the muscle cells during muscle contraction. Glycogen has been identified in other tissues such as brain, heart, kidney, adipose tissue, and erythrocytes, but glycogen function in these tissues is mostly unknown. Glycogen synthesis requires a series of reactions that include glucose entrance into the cell through transporters, phosphorylation of glucose to glucose 6-phosphate, isomerization to glucose 1-phosphate, and formation of uridine 5'-diphosphate-glucose, which is the direct glucose donor for glycogen synthesis. Glycogenin catalyzes the formation of a short glucose polymer that is extended by the action of glycogen synthase. Glycogen branching enzyme introduces branch points in the glycogen particle at even intervals. Laforin and malin are proteins involved in glycogen assembly but their specific function remains elusive in humans. Glycogen is accumulated in the liver primarily during the postprandial period and in the skeletal muscle predominantly after exercise. In the cytosol, glycogen breakdown or glycogenolysis is carried out by two enzymes, glycogen phosphorylase which releases glucose 1-phosphate from the linear chains of glycogen, and glycogen debranching enzyme which untangles the branch points. In the lysosomes, glycogen degradation is catalyzed by α-glucosidase. The glucose 6-phosphatase system catalyzes the dephosphorylation of glucose 6-phosphate to glucose, a necessary step for free glucose to leave the cell. Mutations in the genes encoding the enzymes involved in glycogen metabolism cause glycogen storage diseases. PMID:27051594

  4. Labeling of hepatic glycogen after short- and long-term stimulation of glycogen synthesis in rats injected with 3H-galactose

    SciTech Connect

    Michaels, J.E.; Garfield, S.A.; Hung, J.T.; Cardell, R.R. Jr. )

    1990-08-01

    The effects of short- and long-term stimulation of glycogen synthesis elicited by dexamethasone were studied by light (LM) and electron (EM) microscopic radioautography (RAG) and biochemical analysis. Adrenalectomized rats were fasted overnight and pretreated for short- (3 hr) or long-term (14 hr) periods with dexamethasone prior to intravenous injection of tracer doses of 3H-galactose. Analysis of LM-RAGs from short-term rats revealed that about equal percentages (44%) of hepatocytes became heavily or lightly labeled 1 hr after labeling. The percentage of heavily labeled cells increased slightly 6 hr after labeling, and unlabeled glycogen became apparent in some hepatocytes. The percentage of heavily labeled cells had decreased somewhat 12 hr after labeling, and more unlabeled glycogen was evident. In the long-term rats 1 hr after labeling, a higher percentage of heavily labeled cells (76%) was observed compared to short-term rats, and most glycogen was labeled. In spite of the high amount of labeling seen initially, the percentage of heavily labeled hepatocytes had decreased considerably to 55% by 12 hr after injection; and sparsely labeled and unlabeled glycogen was prevalent. The EM-RAGs of both short- and long-term rats were similar. Silver grains were associated with glycogen patches 1 hr after labeling; 12 hr after labeling, the glycogen patches had enlarged; and label, where present, was dispersed over the enlarged glycogen clumps. Analysis of DPM/mg tissue corroborated the observed decrease in label 12 hr after administration in the long-term animals. The loss of label observed 12 hr after injection in the long-term pretreated rats suggests that turnover of glycogen occurred during this interval despite the net accumulation of glycogen that was visible morphologically and evident from biochemical measurement.

  5. A low calorie morning meal prevents the decline of hepatic glycogen stores: a pilot in vivo (13)C magnetic resonance study.

    PubMed

    Bawden, S J; Stephenson, M C; Ciampi, E; Hunter, K; Marciani, L; Spiller, R C; Aithal, G P; Morris, P G; Macdonald, I A; Gowland, P A

    2014-09-01

    Previous studies have reported a meal-induced rise in hepatic glycogen stores from baseline levels following a fast and it is generally assumed that glycogen levels rise steadily following meals throughout the day. However, measurements are normally taken in conditions that are not typical of the Western breakfast, which is relatively carbohydrate rich with a lower calorific content than most experimental test meals. As such, little is known about the normal metabolic response to a realistic, low calorie morning meal. Therefore, the aim of this pilot study was to evaluate the effects of a low dose oral glucose intake on hepatic glycogen levels following an overnight fast in healthy subjects. Glycogen levels were monitored in vivo using (13)C Magnetic Resonance Spectroscopy at baseline and hourly for 4 hours following either a 50 g glucose drink (773 kJ) or a control drink (0 kJ) given over two different visits. During the control visit hepatic glycogen levels decreased throughout the experiment with statistically significant decreases from baseline at 190 minutes (P < 0.05) and 250 minutes (P < 0.05). By contrast, the low dose glucose intake maintained glycogen concentrations with no significant decrease from baseline over 4 hours. A comparison between visits revealed that mean glycogen concentrations were significantly greater during the glucose visit (control visit, AUC = 218 ± 39 mol L(-1) min(-1); glucose visit, AUC = 305 ± 49 mol L(-1) min(-1); P < 0.05). Liver volume decreased significantly from baseline at 180 minutes (P < 0.05) post consumption in both groups, with no significant difference found between visits. Gastric content volumes were significantly higher for the glucose visit immediately following consumption (P < 0.001) and at 60 minutes (P = 0.007) indicating slower gastric emptying for the glucose compared with the control. In conclusion, following an overnight fast, a low dose oral glucose challenge prevents a reduction in hepatic glycogen

  6. A Txnrd1-dependent metabolic switch alters hepatic lipogenesis, glycogen storage, and detoxification.

    PubMed

    Iverson, Sonya V; Eriksson, Sofi; Xu, Jianqiang; Prigge, Justin R; Talago, Emily A; Meade, Tesia A; Meade, Erin S; Capecchi, Mario R; Arnér, Elias S J; Schmidt, Edward E

    2013-10-01

    Besides helping to maintain a reducing intracellular environment, the thioredoxin (Trx) system impacts bioenergetics and drug metabolism. We show that hepatocyte-specific disruption of Txnrd1, encoding Trx reductase-1 (TrxR1), causes a metabolic switch in which lipogenic genes are repressed and periportal hepatocytes become engorged with glycogen. These livers also overexpress machinery for biosynthesis of glutathione and conversion of glycogen into UDP-glucuronate; they stockpile glutathione-S-transferases and UDP-glucuronyl-transferases; and they overexpress xenobiotic exporters. This realigned metabolic profile suggested that the mutant hepatocytes might be preconditioned to more effectively detoxify certain xenobiotic challenges. Hepatocytes convert the pro-toxin acetaminophen (APAP, paracetamol) into cytotoxic N-acetyl-p-benzoquinone imine (NAPQI). APAP defenses include glucuronidation of APAP or glutathionylation of NAPQI, allowing removal by xenobiotic exporters. We found that NAPQI directly inactivates TrxR1, yet Txnrd1-null livers were resistant to APAP-induced hepatotoxicity. Txnrd1-null livers did not have more effective gene expression responses to APAP challenge; however, their constitutive metabolic state supported more robust GSH biosynthesis, glutathionylation, and glucuronidation systems. Following APAP challenge, this effectively sustained the GSH system and attenuated damage. PMID:23743293

  7. A Txnrd1-dependent metabolic switch alters hepatic lipogenesis, glycogen storage, and detoxification

    PubMed Central

    Iverson, Sonya V.; Eriksson, Sofi; Xu, Jianqiang; Prigge, Justin R.; Talago, Emily A.; Meade, Tesia A.; Meade, Erin S.; Capecchi, Mario R.; Arnér, Elias S.J.; Schmidt, Edward E.

    2013-01-01

    Besides helping to maintain a reducing intracellular environment, the thioredoxin (Trx) system impacts bioenergetics and drug-metabolism. We show that hepatocyte-specific disruption of Txnrd1, encoding Trx reductase-1 (TrxR1), causes a metabolic switch in which lipogenic genes are repressed and periportal hepatocytes become engorged with glycogen. These livers also overexpress machinery for biosynthesis of glutathione and conversion of glycogen into UDP-glucuronate; they stockpile glutathione-S-transferases and UDP-glucuronyl-transferases; and they overexpress xenobiotic exporters. This realigned metabolic profile suggested that the mutant hepatocytes might be preconditioned to more effectively detoxify certain xenobiotic challenges. Hepatocytes convert the pro-toxin acetaminophen (APAP, paracetamol) into cytotoxic N-acetyl-p-benzoquinone imine (NAPQI). APAP defenses include glucuronidation of APAP or glutathionylation of NAPQI, allowing removal by xenobiotic exporters. We found that NAPQI directly inactivates TrxR1, yet Txnrd1-null livers were resistant to APAP-induced hepatotoxicity. Txnrd1-null livers did not have more effective gene expression responses to APAP challenge; however their constitutive metabolic state supported more robust GSH biosynthesis-, glutathionylation-, and glucuronidation-systems. Following APAP challenge, this effectively sustained the GSH system and attenuated damage. PMID:23743293

  8. Effect of chronic supplementation with branched-chain amino acids on the performance and hepatic and muscle glycogen content in trained rats.

    PubMed

    de Araujo, Jonas A; Falavigna, Gina; Rogero, Marcelo M; Pires, Ivanir S O; Pedrosa, Rogerio G; Castro, Inar A; Donato, Jose; Tirapegui, Julio

    2006-08-29

    The objective of this study was to evaluate the effects of a diet supplemented with branched-chain amino acids (BCAA; 3.57% and 4.76%) on the performance and glycogen metabolism of trained rats. Thirty-six adult male Wistar rats received the control diet (AIN-93M) (n=12) and two diets supplemented with BCAA (S1: AIN-93M+3.57% BCAA, n=12, and S2: AIN-93M+4.76% BCAA, n=12) for 6 weeks. The training protocol consisted of bouts of swimming exercise (60 min day(-1)) for 6 weeks at intensities close to the lactate threshold. On the last day of the experiment, all groups were trained for 1 h (1H) or were submitted to the exhaustion test (EX). The time to exhaustion did not differ between groups. The groups submitted to the exhaustion test presented a reduction in plasma glucose and an increase in plasma ammonia and blood lactate concentrations compared to the 1H condition. In the 1H condition, hepatic glycogen concentration was significantly higher in group S2 compared to the control diet and S1 groups (132% and 44%, respectively). Group S2 in the 1H condition presented a higher muscle glycogen concentration (45%) compared to the control diet group. In the EX condition, a significantly higher hepatic glycogen concentration was observed for group S2 compared to the control diet and S1 groups (262% and 222%, respectively). Chronic supplementation with BCAA promoted a higher hepatic and muscle glycogen concentration in trained animals, with this effect being dose dependent. PMID:16698042

  9. Inhibition of hepatic triglyceride formation by clofibrate

    PubMed Central

    Adams, Larry L.; Webb, William W.; Fallon, Harold J.

    1971-01-01

    The effect of clofibrate (CPIB) on hepatic glycerolipid formation has been studied in vivo and in vitro in the rat. Feeding 0.25% CPIB in laboratory chow significantly reduced serum triglyceride levels by 6 hr and concomitantly decreased the rate of glycerol-14C incorporation into hepatic and serum glycerides, in vivo. These changes persisted for at least 14 days. A similar decrease in serum triglyceride and glycerol incorporation into hepatic glycerides was observed in rats fed high glucose diets containing 0.25% CPIB. Serum glycerol was reduced by feeding CPIB for 14 days. The formation of diglyceride and triglyceride from 14C-sn-glycerol-3-P by rat liver homogenates was inhibited by addition of 1-40 mM CPIB to the reaction mixture. These results suggest that CPIB reduces hepatic glycerolipid synthesis, possibly by inhibition of one or more reactions in the esterification of sn-glycerol-3-P. This change may account for the early fall in serum triglyceride. At later time periods, serum glycerol levels fall and in some experiments, hepatic triglyceride content increases. Therefore, it is likely that additional metabolic alterations may contribute to the sustained hypotriglyceridemic effects of CPIB. PMID:5096518

  10. Focal hepatic infarction with bile lake formation

    SciTech Connect

    Peterson, I.M.; Neumann, C.H.

    1984-06-01

    Venous thrombosis associated with oral contraceptives is a well recognized phenomenon. Arterial thrombosis, while less common, is also a known risk, as evidenced by the increased incidence of cerebral vascular accidents and myocardial ischemia or infarction. The liver is relatively protected from the usual consequences of arterial thrombosis because of its dual blood supply. The authors present an unusual case of a young woman with a history of oral contraceptive and cigarette use who developed hepatic artery thrombosis and had focal liver lesions on computed tomography (CT) due to hepatic infarction and bile lake formation despite an intact portal venous system.

  11. NATURAL HISTORY OF HEPATOCELLULAR ADENOMA FORMATION IN GLYCOGEN STORAGE DISEASE TYPE I

    PubMed Central

    Wang, David Q.; Fiske, Laurie M.; Carreras, Caroline T.; Weinstein, David A.

    2011-01-01

    Objective To characterize the natural history and factors related to hepatocellular adenoma (HCA) development in glycogen storage disease type I (GSD I). Study design Retrospective chart review was performed for 117 patients with GSD I. Kaplan-Meier analysis of HCA progression among two groups of patients with GSD Ia (five-year mean triglyceride concentration ≤500 mg/dL and >500 mg/dL); analysis of serum triglyceride concentration, body mass index (BMI) standard deviation score (SDS), and height SDS between cases at time of HCA diagnosis and age- and sex-matched controls. Results Logrank analysis of Kaplan-Meier survival curve demonstrated a significant difference in progression to HCA between the five-year mean triglyceride groups (p = 0.008). No significant difference was detected in progression to adenoma event between sexes. Serum triglyceride concentration was significantly different at time of diagnosis of adenoma (737±422 mg/dL) compared with controls (335±195 mg/dL) (p = 0.009). Differences in height SDS (p = 0.051) and BMI SDS (p = 0.066) approached significance in our case-control analysis. Conclusion Metabolic control may be related to HCA formation in patients with GSD Ia. Optimizing metabolic control remains critical, and further studies are warranted to understand the pathogenesis of adenoma development. PMID:21481415

  12. Irisin inhibits hepatic gluconeogenesis and increases glycogen synthesis via the PI3K/Akt pathway in type 2 diabetic mice and hepatocytes.

    PubMed

    Liu, Tong-Yan; Shi, Chang-Xiang; Gao, Run; Sun, Hai-Jian; Xiong, Xiao-Qing; Ding, Lei; Chen, Qi; Li, Yue-Hua; Wang, Jue-Jin; Kang, Yu-Ming; Zhu, Guo-Qing

    2015-11-01

    Increased glucose production and reduced hepatic glycogen storage contribute to metabolic abnormalities in diabetes. Irisin, a newly identified myokine, induces the browning of white adipose tissue, but its effects on gluconeogenesis and glycogenesis are unknown. In the present study, we investigated the effects and underlying mechanisms of irisin on gluconeogenesis and glycogenesis in hepatocytes with insulin resistance, and its therapeutic role in type 2 diabetic mice. Insulin resistance was induced by glucosamine (GlcN) or palmitate in human hepatocellular carcinoma (HepG2) cells and mouse primary hepatocytes. Type 2 diabetes was induced by streptozotocin/high-fat diet (STZ/HFD) in mice. In HepG2 cells, irisin ameliorated the GlcN-induced increases in glucose production, phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G6Pase) expression, and glycogen synthase (GS) phosphorylation; it prevented GlcN-induced decreases in glycogen content and the phosphoinositide 3-kinase (PI3K) p110α subunit level, and the phosphorylation of Akt/protein kinase B, forkhead box transcription factor O1 (FOXO1) and glycogen synthase kinase-3 (GSK3). These effects of irisin were abolished by the inhibition of PI3K or Akt. The effects of irisin were confirmed in mouse primary hepatocytes with GlcN-induced insulin resistance and in human HepG2 cells with palmitate-induced insulin resistance. In diabetic mice, persistent subcutaneous perfusion of irisin improved the insulin sensitivity, reduced fasting blood glucose, increased GSK3 and Akt phosphorylation, glycogen content and irisin level, and suppressed GS phosphorylation and PEPCK and G6Pase expression in the liver. Irisin improves glucose homoeostasis by reducing gluconeogenesis via PI3K/Akt/FOXO1-mediated PEPCK and G6Pase down-regulation and increasing glycogenesis via PI3K/Akt/GSK3-mediated GS activation. Irisin may be regarded as a novel therapeutic strategy for insulin resistance and type 2 diabetes. PMID

  13. History of Hepatic Bile Formation: Old Problems, New Approaches

    ERIC Educational Resources Information Center

    Javitt, Norman B.

    2014-01-01

    Studies of hepatic bile formation reported in 1958 established that it was an osmotically generated water flow. Intravenous infusion of sodium taurocholate established a high correlation between hepatic bile flow and bile acid excretion. Secretin, a hormone that stimulates bicarbonate secretion, was also found to increase hepatic bile flow. The…

  14. In vivo hepatic lipid quantification using MRS at 7 Tesla in a mouse model of glycogen storage disease type 1a

    PubMed Central

    Ramamonjisoa, Nirilanto; Ratiney, Helene; Mutel, Elodie; Guillou, Herve; Mithieux, Gilles; Pilleul, Frank; Rajas, Fabienne; Beuf, Olivier; Cavassila, Sophie

    2013-01-01

    The assessment of liver lipid content and composition is needed in preclinical research to investigate steatosis and steatosis-related disorders. The purpose of this study was to quantify in vivo hepatic fatty acid content and composition using a method based on short echo time proton magnetic resonance spectroscopy (MRS) at 7 Tesla. A mouse model of glycogen storage disease type 1a with inducible liver-specific deletion of the glucose-6-phosphatase gene (L-G6pc−/−) mice and control mice were fed a standard diet or a high-fat/high-sucrose (HF/HS) diet for 9 months. In control mice, hepatic lipid content was found significantly higher with the HF/HS diet than with the standard diet. As expected, hepatic lipid content was already elevated in L-G6pc−/− mice fed a standard diet compared with control mice. L-G6pc−/− mice rapidly developed steatosis which was not modified by the HF/HS diet. On the standard diet, estimated amplitudes from olefinic protons were found significantly higher in L-G6pc−/− mice compared with that in control mice. L-G6pc−/− mice showed no noticeable polyunsaturation from diallylic protons. Total unsaturated fatty acid indexes measured by gas chromatography were in agreement with MRS measurements. These results showed the great potential of high magnetic field MRS to follow the diet impact and lipid alterations in mouse liver. PMID:23596325

  15. Malignant Transformation of Hepatic Adenoma in Glycogen Storage Disease Type-1a: Report of an Exceptional Case Diagnosed on Surveillance Imaging

    PubMed Central

    Baheti, Akshay D.; Yeh, Matthew M.; O'Malley, Ryan; Lalwani, Neeraj

    2015-01-01

    Hepatocellular adenoma is a heterogeneous group of benign neoplasms arising from hepatocellular cells and can be subclassified into four major groups based on genotypic and phenotypic characteristics. These four subtypes are hepatocyte nuclear factor (HNF) 1α-inactivated, β-catenin–activated, inflammatory, and unclassified adenomas. Immunohistochemistry studies have demonstrated that since β-catenin–activated adenomas have a higher risk of malignant transformation, the identification of the subtype of adenoma remains crucial in patient management. However, malignant transformation of hepatic adenoma without β-catenin overexpression can be seen in 30–65% cases. We report a case of malignant transformation of hepatic adenoma without overexpression of β-catenin in a 31-year-old man with a known glycogen storage disease (GSD) Type-1a, which was diagnosed on surveillance magnetic resonance imaging (MRI). The MRI showed a mild interval increase in one lesion with relative stability of the other adenomas. The lesion was presumed to be suspicious for a hepatocellular carcinoma (HCC) and was confirmed on pathology. PMID:26430540

  16. Glycogen metabolism in humans☆☆☆

    PubMed Central

    Adeva-Andany, María M.; González-Lucán, Manuel; Donapetry-García, Cristóbal; Fernández-Fernández, Carlos; Ameneiros-Rodríguez, Eva

    2016-01-01

    In the human body, glycogen is a branched polymer of glucose stored mainly in the liver and the skeletal muscle that supplies glucose to the blood stream during fasting periods and to the muscle cells during muscle contraction. Glycogen has been identified in other tissues such as brain, heart, kidney, adipose tissue, and erythrocytes, but glycogen function in these tissues is mostly unknown. Glycogen synthesis requires a series of reactions that include glucose entrance into the cell through transporters, phosphorylation of glucose to glucose 6-phosphate, isomerization to glucose 1-phosphate, and formation of uridine 5ʹ-diphosphate-glucose, which is the direct glucose donor for glycogen synthesis. Glycogenin catalyzes the formation of a short glucose polymer that is extended by the action of glycogen synthase. Glycogen branching enzyme introduces branch points in the glycogen particle at even intervals. Laforin and malin are proteins involved in glycogen assembly but their specific function remains elusive in humans. Glycogen is accumulated in the liver primarily during the postprandial period and in the skeletal muscle predominantly after exercise. In the cytosol, glycogen breakdown or glycogenolysis is carried out by two enzymes, glycogen phosphorylase which releases glucose 1-phosphate from the linear chains of glycogen, and glycogen debranching enzyme which untangles the branch points. In the lysosomes, glycogen degradation is catalyzed by α-glucosidase. The glucose 6-phosphatase system catalyzes the dephosphorylation of glucose 6-phosphate to glucose, a necessary step for free glucose to leave the cell. Mutations in the genes encoding the enzymes involved in glycogen metabolism cause glycogen storage diseases. PMID:27051594

  17. Biomarker for Glycogen Storage Diseases

    ClinicalTrials.gov

    2016-08-25

    Fructose Metabolism, Inborn Errors; Glycogen Storage Disease; Glycogen Storage Disease Type I; Glycogen Storage Disease Type II; Glycogen Storage Disease Type III; Glycogen Storage Disease Type IV; Glycogen Storage Disease Type V; Glycogen Storage Disease Type VI; Glycogen Storage Disease Type VII; Glycogen Storage Disease Type VIII

  18. [Multiple calcium oxalate stone formation in a patient with glycogen storage disease type I (von Gierke's disease) and renal tubular acidosis type I: a case report].

    PubMed

    Kanematsu, A; Segawa, T; Kakehi, Y; Takeuchi, H

    1993-07-01

    A case of multiple urinary stones in a patient with glycogen storage disease type 1 (GSD-1) is reported. In spite of the presence of hyperuricemia, these stones did not consist of uric acid, but mainly of calcium oxalate. Laboratory studies revealed distal renal tubular acidosis and hypocitraturia, but no significant abnormality in calcium metabolism. We discussed the mechanism of calcium stone formation in our case, and its prophylactic treatment by oral administration of citrate compound. PMID:8362684

  19. Liver Glycogen Loading Dampens Glycogen Synthesis Seen in Response to Either Hyperinsulinemia or Intraportal Glucose Infusion

    PubMed Central

    Winnick, Jason J.; An, Zhibo; Kraft, Guillaume; Ramnanan, Christopher J.; Irimia, Jose M.; Smith, Marta; Lautz, Margaret; Roach, Peter J.; Cherrington, Alan D.

    2013-01-01

    The purpose of this study was to determine the effect of liver glycogen loading on net hepatic glycogen synthesis during hyperinsulinemia or hepatic portal vein glucose infusion in vivo. Liver glycogen levels were supercompensated (SCGly) in two groups (using intraportal fructose infusion) but not in two others (Gly) during hyperglycemic-normoinsulinemia. Following a 2-h control period during which fructose infusion was stopped, there was a 2-h experimental period in which the response to hyperglycemia plus either 4× basal insulin (INS) or portal vein glucose infusion (PoG) was measured. Increased hepatic glycogen reduced the percent of glucose taken up by the liver that was deposited in glycogen (74 ± 3 vs. 53 ± 5% in Gly+INS and SCGly+INS, respectively, and 72 ± 3 vs. 50 ± 6% in Gly+PoG and SCGly+PoG, respectively). The reduction in liver glycogen synthesis in SCGly+INS was accompanied by a decrease in both insulin signaling and an increase in AMPK activation, whereas only the latter was observed in SCGly+PoG. These data indicate that liver glycogen loading impairs glycogen synthesis regardless of the signal used to stimulate it. PMID:22923473

  20. Matrix metalloproteinase-14 mediates formation of bile ducts and hepatic maturation of fetal hepatic progenitor cells.

    PubMed

    Otani, Satoshi; Kakinuma, Sei; Kamiya, Akihide; Goto, Fumio; Kaneko, Shun; Miyoshi, Masato; Tsunoda, Tomoyuki; Asano, Yu; Kawai-Kitahata, Fukiko; Nitta, Sayuri; Nakata, Toru; Okamoto, Ryuichi; Itsui, Yasuhiro; Nakagawa, Mina; Azuma, Seishin; Asahina, Yasuhiro; Yamaguchi, Tomoyuki; Koshikawa, Naohiko; Seiki, Motoharu; Nakauchi, Hiromitsu; Watanabe, Mamoru

    2016-01-22

    Fetal hepatic stem/progenitor cells, called hepatoblasts, play central roles in liver development; however, the molecular mechanisms regulating the phenotype of these cells have not been completely elucidated. Matrix metalloproteinase (MMP)-14 is a type I transmembrane proteinase regulating pericellular proteolysis of the extracellular matrix and is essential for the activation of several MMPs and cytokines. However, the physiological functions of MMP-14 in liver development are unknown. Here we describe a functional role for MMP-14 in hepatic and biliary differentiation of mouse hepatoblasts. MMP-14 was upregulated in cells around the portal vein in perinatal stage liver. Formation of bile duct-like structures in MMP-14-deficient livers was significantly delayed compared with wild-type livers in vivo. In vitro biliary differentiation assays showed that formation of cholangiocytic cysts derived from MMP-14-deficient hepatoblasts was completely impaired, and that overexpression of MMP-14 in hepatoblasts promoted the formation of bile duct-like cysts. In contrast, the expression of molecules associated with metabolic functions in hepatocytes, including hepatic nuclear factor 4α and tryptophan 2,3-dioxygenase, were significantly increased in MMP-14-deficient livers. Expression of the epidermal growth factor receptor and phosphorylation of mitogen-activated protein kinases were significantly upregulated in MMP-14-deficient livers. We demonstrate that MMP-14-mediated signaling in fetal hepatic progenitor cells promotes biliary luminal formation around the portal vein and negatively controls the maturation of hepatocytes. PMID:26724533

  1. In vitro digestion of starches in a dynamic gastrointestinal model: an innovative study to optimize dietary management of patients with hepatic glycogen storage diseases.

    PubMed

    Nalin, Tatiéle; Venema, Koen; Weinstein, David A; de Souza, Carolina F M; Perry, Ingrid D S; van Wandelen, Mario T R; van Rijn, Margreet; Smit, G Peter A; Schwartz, Ida V D; Derks, Terry G J

    2015-05-01

    Uncooked cornstarch (UCCS) is a widely used treatment strategy for patients with hepatic glycogen storage disease (GSD). It has been observed that GSD-patients display different metabolic responses to different cornstarches. The objective was to characterize starch fractions and analyze the digestion of different starches in a dynamic gastrointestinal in vitro model. The following brands of UCCS were studied: Argo and Great Value from the United States of America; Brazilian Maizena Duryea and Yoki from Brazil; Dutch Maizena Duryea from the Netherlands. Glycosade, a modified starch, and sweet polvilho, a Brazilian starch extracted from cassava, were also studied. The starch fractions were analyzed by glycemic TNO index method and digestion analyses were determined by the TIM-1 system, a dynamic, computer-controlled, in vitro gastrointestinal model, which simulates the stomach and small intestine. The final digested amounts were between 84 and 86% for the UCCS and Glycosade, but was 75.5% for sweet povilho. At 180 min of the experiment, an important time-point for GSD patients, the digested amount of the starches corresponded to 67.9-71.5 for the UCCS and Glycosade, while it was 55.5% for sweet povilho. In an experiment with a mixture of sweet polvilho and Brazilian Maizena Duryea, a final digested amount of 78.4% was found, while the value at 180 min was 61.7%. Sweet polvilho seems to have a slower and extended release of glucose and looks like an interesting product to be further studied as it might lead to extended normoglycemia in GSD-patients. PMID:25224825

  2. Protein kinase R-like endoplasmic reticulum kinase and glycogen synthase kinase-3α/β regulate foam cell formation[S

    PubMed Central

    McAlpine, Cameron S.; Werstuck, Geoff H.

    2014-01-01

    Evidence suggests a causative role for endoplasmic reticulum (ER) stress in the development of atherosclerosis. This study investigated the potential role of glycogen synthase kinase (GSK)-3α/β in proatherogenic ER stress signaling. Thp1-derived macrophages were treated with the ER stress-inducing agents, glucosamine, thapsigargin, or palmitate. Using small-molecule inhibitors of specific unfolded protein response (UPR) signaling pathways, we found that protein kinase R-like ER kinase (PERK), but not inositol requiring enzyme 1 or activating transcription factor 6, is required for the activation of GSK3α/β by ER stress. GSK3α/β inhibition or siRNA-directed knockdown attenuated ER stress-induced expression of distal components of the PERK pathway. Macrophage foam cells within atherosclerotic plaques and isolated macrophages from ApoE−/− mice fed a diet supplemented with the GSK3α/β inhibitor valproate had reduced levels of C/EBP homologous protein (CHOP). GSK3α/β inhibition blocked ER stress-induced lipid accumulation and the upregulation of genes associated with lipid metabolism. In primary mouse macrophages, PERK inhibition blocked ER stress-induced lipid accumulation, whereas constitutively active S9A-GSK3β promoted foam cell formation and CHOP expression, even in cells treated with a PERK inhibitor. These findings suggest that ER stress-PERK-GSK3α/β signaling promotes proatherogenic macrophage lipid accumulation. PMID:25183803

  3. Glycogen storage diseases: New perspectives

    PubMed Central

    Özen, Hasan

    2007-01-01

    Glycogen storage diseases (GSD) are inherited metabolic disorders of glycogen metabolism. Different hormones, including insulin, glucagon, and cortisol regulate the relationship of glycolysis, gluconeogenesis and glycogen synthesis. The overall GSD incidence is estimated 1 case per 20000-43000 live births. There are over 12 types and they are classified based on the enzyme deficiency and the affected tissue. Disorders of glycogen degradation may affect primarily the liver, the muscle, or both. Type Ia involves the liver, kidney and intestine (and Ib also leukocytes), and the clinical manifestations are hepatomegaly, failure to thrive, hypoglycemia, hyperlactatemia, hyperuricemia and hyperlipidemia. Type IIIa involves both the liver and muscle, and IIIb solely the liver. The liver symptoms generally improve with age. Type IV usually presents in the first year of life, with hepatomegaly and growth retardation. The disease in general is progressive to cirrhosis. Type VI and IX are a heterogeneous group of diseases caused by a deficiency of the liver phosphorylase and phosphorylase kinase system. There is no hyperuricemia or hyperlactatemia. Type XI is characterized by hepatic glycogenosis and renal Fanconi syndrome. Type II is a prototype of inborn lysosomal storage diseases and involves many organs but primarily the muscle. Types V and VII involve only the muscle. PMID:17552001

  4. The 3T3-L1 adipocyte glycogen proteome

    PubMed Central

    2013-01-01

    Background Glycogen is a branched polysaccharide of glucose residues, consisting of α-1-4 glycosidic linkages with α-1-6 branches that together form multi-layered particles ranging in size from 30 nm to 300 nm. Glycogen spatial conformation and intracellular organization are highly regulated processes. Glycogen particles interact with their metabolizing enzymes and are associated with a variety of proteins that intervene in its biology, controlling its structure, particle size and sub-cellular distribution. The function of glycogen in adipose tissue is not well understood but appears to have a pivotal role as a regulatory mechanism informing the cells on substrate availability for triacylglycerol synthesis. To provide new molecular insights into the role of adipocyte glycogen we analyzed the glycogen-associated proteome from differentiated 3T3-L1-adipocytes. Results Glycogen particles from 3T3-L1-adipocytes were purified using a series of centrifugation steps followed by specific elution of glycogen bound proteins using α-1,4 glucose oligosaccharides, or maltodextrins, and tandem mass spectrometry. We identified regulatory proteins, 14-3-3 proteins, RACK1 and protein phosphatase 1 glycogen targeting subunit 3D. Evidence was also obtained for a regulated subcellular distribution of the glycogen particle: metabolic and mitochondrial proteins were abundant. Unlike the recently analyzed hepatic glycogen proteome, no endoplasmic proteins were detected, along with the recently described starch-binding domain protein 1. Other regulatory proteins which have previously been described as glycogen-associated proteins were not detected, including laforin, the AMPK beta-subunit and protein targeting to glycogen (PTG). Conclusions These data provide new molecular insights into the regulation of glycogen-bound proteins that are associated with the maintenance, organization and localization of the adipocyte glycogen particle. PMID:23521774

  5. Hepatitis

    MedlinePlus

    ... Got Homework? Here's Help White House Lunch Recipes Hepatitis KidsHealth > For Kids > Hepatitis Print A A A ... an important digestive liquid called bile . What Is Hepatitis? Hepatitis is an inflammation (say: in-fluh-MAY- ...

  6. Specific features of glycogen metabolism in the liver.

    PubMed Central

    Bollen, M; Keppens, S; Stalmans, W

    1998-01-01

    Although the general pathways of glycogen synthesis and glycogenolysis are identical in all tissues, the enzymes involved are uniquely adapted to the specific role of glycogen in different cell types. In liver, where glycogen is stored as a reserve of glucose for extrahepatic tissues, the glycogen-metabolizing enzymes have properties that enable the liver to act as a sensor of blood glucose and to store or mobilize glycogen according to the peripheral needs. The prime effector of hepatic glycogen deposition is glucose, which blocks glycogenolysis and promotes glycogen synthesis in various ways. Other glycogenic stimuli for the liver are insulin, glucocorticoids, parasympathetic (vagus) nerve impulses and gluconeogenic precursors such as fructose and amino acids. The phosphorolysis of glycogen is mainly mediated by glucagon and by the orthosympathetic neurotransmitters noradrenaline and ATP. Many glycogenolytic stimuli, e.g. adenosine, nucleotides and NO, also act indirectly, via secretion of eicosanoids from non-parenchymal cells. Effectors often initiate glycogenolysis cooperatively through different mechanisms. PMID:9806880

  7. Glycogen branches out: new perspectives on the role of glycogen metabolism in the integration of metabolic pathways.

    PubMed

    Greenberg, Cynthia C; Jurczak, Michael J; Danos, Arpad M; Brady, Matthew J

    2006-07-01

    Glycogen is the storage form of carbohydrate for virtually every organism from yeast to primates. Most mammalian tissues store glucose as glycogen, with the major depots located in muscle and liver. The French physiologist Claude Bernard first identified a starch-like substance in liver and muscle and coined the term glycogen, or "sugar former," in the 1850s. During the 150 years since its identification, researchers in the field of glycogen metabolism have made numerous discoveries that are now recognized as significant milestones in biochemistry and cell signaling. Even so, more questions remain, and studies continue to demonstrate the complexity of the regulation of glycogen metabolism. Under classical definitions, the functions of glycogen seem clear: muscle glycogen is degraded to generate ATP during increased energy demand, whereas hepatic glycogen is broken down for release of glucose into the bloodstream to supply other tissues. However, recent findings demonstrate that the roles of glycogen metabolism in energy sensing, integration of metabolic pathways, and coordination of cellular responses to hormonal stimuli are far more complex. PMID:16478770

  8. Computed tomography of the liver and kidneys in glycogen storage disease.

    PubMed

    Doppman, J L; Cornblath, M; Dwyer, A J; Adams, A J; Girton, M E; Sidbury, J

    1982-02-01

    Glycogen, in concentrations encountered in von Gierke's disease, has computed tomography (CT) attenuation coefficients in the 50 to 70 Hounsfield unit (HU: 1,000 scale) range and accounts for the increased density of the liver. However, in eight patients with Type I glycogen storage disease, simultaneous hepatic infiltration with fat and glycogen led to a range of liver CT densities from 13 to 80 HU. Fatty infiltration may facilitate the demonstration of hepatic tumors in older patients with this disease. Half the patients showed increased attenuation coefficients of the renal cortex, indicating glycogen deposition in the kidneys. PMID:6950959

  9. Human stem cell osteoblastogenesis mediated by novel glycogen synthase kinase 3 inhibitors induces bone formation and a unique bone turnover biomarker profile in rats

    SciTech Connect

    Gilmour, Peter S.; O'Shea, Patrick J.; Fagura, Malbinder; Pilling, James E.; Sanganee, Hitesh; Wada, Hiroki; Courtney, Paul F.; Kavanagh, Stefan; Hall, Peter A.; Escott, K. Jane

    2013-10-15

    Wnt activation by inhibiting glycogen synthase kinase 3 (GSK-3) causes bone anabolism in rodents making GSK-3 a potential therapeutic target for osteoporotic and osteolytic metastatic bone disease. To understand the wnt pathway related to human disease translation, the ability of 3 potent inhibitors of GSK-3 (AZD2858, AR79, AZ13282107) to 1) drive osteoblast differentiation and mineralisation using human adipose-derived stem cells (hADSC) in vitro; and 2) stimulate rat bone formation in vivo was investigated. Bone anabolism/resorption was determined using clinically relevant serum biomarkers as indicators of bone turnover and bone formation assessed in femurs by histopathology and pQCT/μCT imaging. GSK-3 inhibitors caused β-catenin stabilisation in human and rat mesenchymal stem cells, stimulated hADSC commitment towards osteoblasts and osteogenic mineralisation in vitro. AZD2858 produced time-dependent changes in serum bone turnover biomarkers and increased bone mass over 28 days exposure in rats. After 7 days, AZD2858, AR79 or AZ13282107 exposure increased the bone formation biomarker P1NP, and reduced the resorption biomarker TRAcP-5b, indicating increased bone anabolism and reduced resorption in rats. This biomarker profile was differentiated from anabolic agent PTH{sub 1–34} or the anti-resorptive Alendronate-induced changes. Increased bone formation in cortical and cancellous bone as assessed by femur histopathology supported biomarker changes. 14 day AR79 treatment increased bone mineral density and trabecular thickness, and decreased trabecular number and connectivity assessed by pQCT/μCT. GSK-3 inhibition caused hADSC osteoblastogenesis and mineralisation in vitro. Increased femur bone mass associated with changes in bone turnover biomarkers confirmed in vivo bone formation and indicated uncoupling of bone formation and resorption. - Highlights: • Wnt modulation with 3 novel GSK-3 inhibitors alters bone growth. • Human stem cell osteoblastogenesis

  10. Scintigraphic abnormalities in glycogen storage disease.

    PubMed

    Miller, J H; Gates, G F; Landing, B H; Kogut, M D; Roe, T F

    1978-04-01

    Fifteen patients with glycogen-storage disease type 1 (von Gierke's disease) were evaluated by serial scintigraphy, with a clearly recognizable pattern of an enlarged liver with diminished radionuclide accumulation, splenomegaly with considerably increased uptake and renomegaly. In seven of these patients with GSD-1 scintigraphy demonstrated focal defects of varying size. Small or stable defects suggest benign hepatic adenomata, whereas malignant change occurred in growing large lesions. The potential malignant end-point of hepatic-cell carcinoma in GSD-1 warrants careful serial liver scintigraphy with scintiangiography on a routine basis. PMID:204758

  11. Hepatitis

    MedlinePlus

    ... has been associated with drinking contaminated water. Hepatitis Viruses Type Transmission Prognosis A Fecal-oral (stool to ... risk for severe disease. Others A variety of viruses can affect the liver Signs and Symptoms Hepatitis ...

  12. Hepatitis

    MedlinePlus

    ... be serious. Some can lead to scarring, called cirrhosis, or to liver cancer. Sometimes hepatitis goes away by itself. If it does not, it can be treated with drugs. Sometimes hepatitis lasts a lifetime. Vaccines can help prevent some viral forms.

  13. Metabolic Crosstalk: Molecular Links Between Glycogen and Lipid Metabolism in Obesity

    PubMed Central

    Lu, Binbin; Bridges, Dave; Yang, Yemen; Fisher, Kaleigh; Cheng, Alan; Chang, Louise; Meng, Zhuo-Xian; Lin, Jiandie D.; Downes, Michael; Yu, Ruth T.; Liddle, Christopher; Evans, Ronald M.

    2014-01-01

    Glycogen and lipids are major storage forms of energy that are tightly regulated by hormones and metabolic signals. We demonstrate that feeding mice a high-fat diet (HFD) increases hepatic glycogen due to increased expression of the glycogenic scaffolding protein PTG/R5. PTG promoter activity was increased and glycogen levels were augmented in mice and cells after activation of the mechanistic target of rapamycin complex 1 (mTORC1) and its downstream target SREBP1. Deletion of the PTG gene in mice prevented HFD-induced hepatic glycogen accumulation. Of note, PTG deletion also blocked hepatic steatosis in HFD-fed mice and reduced the expression of numerous lipogenic genes. Additionally, PTG deletion reduced fasting glucose and insulin levels in obese mice while improving insulin sensitivity, a result of reduced hepatic glucose output. This metabolic crosstalk was due to decreased mTORC1 and SREBP activity in PTG knockout mice or knockdown cells, suggesting a positive feedback loop in which once accumulated, glycogen stimulates the mTORC1/SREBP1 pathway to shift energy storage to lipogenesis. Together, these data reveal a previously unappreciated broad role for glycogen in the control of energy homeostasis. PMID:24722244

  14. Temporary accumulation of glycogen in the epithelial cells of the developing mouse submandibular gland.

    PubMed

    Matsuura, Sachiko; Koyama, Noriko; Kashimata, Masanori; Hayashi, Haruki; Kikuta, Akio

    2007-09-01

    Temporary accumulation of glycogen in the epithelial cells of the developing mouse submandibular gland was examined under light microscopic histochemistry and electron microscopy. To avoid loss of water-soluble glycogen during histological tissue preparation, fixation with ethanol and embedding in hydrophilic glycol methacrylate resin was used for light microscopy, and high-pressure freezing/freeze substitution for electron microscopy. Glycogen was detected on periodic acid-Schiff stain, periodic acid-thiosemicarbazide-silver proteinate reaction, and the digestion test with alpha-amylase. On embryonic day 14, glycogen began to accumulate in the proximal portions of the developing epithelial cords. On embryonic day 17, marked glycogen particles were seen at the basal portion of the ductal epithelial cells and an abrupt increase of glycogen accumulation occurred in the secretory cells in the terminal bulbs. Ultrastructural observation indicated large clumps of glycogen particles localized in the basal portion of the terminal bulb cells. The initiation of glycogen accumulation preceded the formation of lumens in the ducts and terminal bulbs. Furthermore, proliferation analysis by bromodeoxyuridine labeling showed that this glycogen accumulation followed the cessation of the epithelial cell proliferation. Postnatally, glycogen accumulation in the terminal bulbs became gradually inconspicuous and completely disappeared by postnatal day 3, but that in the ducts was retained until around postnatal day 12. Temporary glycogen accumulation after the cell proliferation and before/during the lumen formation and secretory granule formation suggests significant involvement of the carbohydrate metabolism in the organogenesis of the submandibular gland. PMID:17867343

  15. Stimulators and Inhibitors of Hepatic Porphyrin Formation in Human Sera

    PubMed Central

    Rifkind, Arleen B.; Sassa, Shigeru; Merkatz, Irwin R.; Winchester, Robert; Harber, Leonard; Kappas, Attallah

    1974-01-01

    Human sera were found to contain factors that stimulate and factors that inhibit porphyrin formation by cultured avian liver cells. The capacity of sera to stimulate or inhibit porphyrin formation varied in different hormonal states and in the porphyrias. Sera from 31 post partum women, eight of whom were not lactating, inhibited porphyrin formation to a mean level 30% below the level in control cultures and also inhibited drug and steroid stimulation of porphyrin formation. In contrast, mean porphyrin formation compared to control cultures was increased between 9 and 21% by sera from 52 normal subjects, 16 women on oral contraceptives, and 11 pregnant women. It was increased 193% by sera from nine subjects with acute intermittent porphyria and 172% by sera from 13 subjects with porphyria cutanea tarda. Heated sera or ethanol extracts of sera from all groups of subjects further increased the mean porphyrin stimulation by sera and, for the post partum subjects, eliminated the inhibitory effect. Ethanol extracts of sera from 28 oral contraceptive-treated women caused significantly greater mean stimulation of porphyrin formation than did extracts of sera from 30 normal women. While sera from 17 out of 22 porphyric subjects contained both stimulatory and inhibitory factors, 5 out of 22 had no evidence of an inhibitory component. There appeared to be heterogeneity in the occurrence of the factors among porphyrics. The factor(s) in sera responsible for porphyrin stimulation were heat-stable and insensitive to trypsin; were present in the supernates after ethanol precipitation of plasma proteins; were extractable in ethyl acetate and nondialyzable; and they migrated with the albumincontaining fraction of serum during electrophoresis. The factor(s) responsible for porphyrin inhibition were heat labile, sensitive to trypsin, and resistant to neuraminidase; were present in the ethanol precipitates of sera and were nondialyzable; and they migrated with the gamma globulin

  16. The control of glycogen metabolism in yeast. 1. Interconversion in vivo of glycogen synthase and glycogen phosphorylase induced by glucose, a nitrogen source or uncouplers.

    PubMed

    François, J; Villanueva, M E; Hers, H G

    1988-06-15

    The addition of glucose to a suspension of yeast initiated glycogen synthesis and ethanol formation. Other effects of the glucose addition were a transient rise in the concentration of cyclic AMP and a more prolonged increase in the concentration of hexose 6-monophosphate and of fructose 2,6-bisphosphate. The activity of glycogen synthase increased about 4-fold and that of glycogen phosphorylase decreased 3-5-fold. These changes could be reversed by the removal of glucose from the medium and induced again by a new addition of the sugar. These effects of glucose were also obtained with glucose derivatives known to form the corresponding 6-phosphoester. Similar changes in glycogen synthase and glycogen phosphorylase activity were induced by glucose in a thermosensitive mutant deficient in adenylate cyclase (cdc35) when incubated at the permissive temperature of 26 degrees C, but were much more pronounced at the nonpermissive temperature of 35 degrees C. Under the latter condition, glycogen synthase was nearly fully activated and glycogen phosphorylase fully inactivated. Such large effects of glucose were, however, not seen in another adenylate-cyclase-deficient mutant (cyr1), able to incorporate exogenous cyclic AMP. When a nitrogen source or uncouplers were added to the incubation medium after glucose, they had effects on glycogen metabolism and on the activity of glycogen synthase and glycogen phosphorylase which were directly opposite to those of glucose. By contrast, like glucose, these agents also caused, under most experimental conditions, a detectable rise in cyclic AMP concentration and a series of cyclic-AMP-dependent effects such as an activation of phosphofructokinase 2 and of trehalase and an increase in the concentration of fructose 2,6-bisphosphate and in the rate of glycolysis. Under all experimental conditions, the rate of glycolysis was proportional to the concentration of fructose 2,6-bisphosphate. Uncouplers, but not a nitrogen source, also induced

  17. A Whole-Body Model for Glycogen Regulation Reveals a Critical Role for Substrate Cycling in Maintaining Blood Glucose Homeostasis

    PubMed Central

    Xu, Ke; Morgan, Kevin T.; Todd Gehris, Abby; Elston, Timothy C.; Gomez, Shawn M.

    2011-01-01

    Timely, and sometimes rapid, metabolic adaptation to changes in food supply is critical for survival as an organism moves from the fasted to the fed state, and vice versa. These transitions necessitate major metabolic changes to maintain energy homeostasis as the source of blood glucose moves away from ingested carbohydrates, through hepatic glycogen stores, towards gluconeogenesis. The integration of hepatic glycogen regulation with extra-hepatic energetics is a key aspect of these adaptive mechanisms. Here we use computational modeling to explore hepatic glycogen regulation under fed and fasting conditions in the context of a whole-body model. The model was validated against previous experimental results concerning glycogen phosphorylase a (active) and glycogen synthase a dynamics. The model qualitatively reproduced physiological changes that occur during transition from the fed to the fasted state. Analysis of the model reveals a critical role for the inhibition of glycogen synthase phosphatase by glycogen phosphorylase a. This negative regulation leads to high levels of glycogen synthase activity during fasting conditions, which in turn increases substrate (futile) cycling, priming the system for a rapid response once an external source of glucose is restored. This work demonstrates that a mechanistic understanding of the design principles used by metabolic control circuits to maintain homeostasis can benefit from the incorporation of mathematical descriptions of these networks into “whole-body” contextual models that mimic in vivo conditions. PMID:22163177

  18. Glycogen synthase activation in human skeletal muscle: effects of diet and exercise.

    PubMed

    Kochan, R G; Lamb, D R; Lutz, S A; Perrill, C V; Reimann, E M; Schlender, K K

    1979-06-01

    We investigated the role of glycogen synthase in supranormal resynthesis (supercompensation) of skeletal muscle glycogen after exhaustive exercise. Six healthy men exercised 60 min by cycling with one leg at 75% VO2max, recovered 3 days on a low-carbohydrate diet, exercised again, and recovered 4 days on high-carbohydrate diet. Glycogen and glycogen synthase activities at several glucose-6-phosphate (G6P) concentrations were measured in biopsy samples of m. vastus lateralis. Dietary alterations alone did not affect glycogen, whereas exercise depleted glycogen stores. After the second exercise bout, glycogen returned to normal within 24 h and reached supercompensated levels by 48 h of recovery. Glycogen synthase activation state strikingly increased after exercise in exercised muscle and remained somewhat elevated for the first 48 h of recovery in both muscles. We suggest that 1) forms of glycogen synthase intermediate to I (G6P-independent) and D (G6P-dependent) forms are present in vivo, and 2) glycogen supercompensation can in part be explained by the formation of intermediate forms of glycogen synthase that exhibit relatively low activity ratios, but an increased sensitivity to activation by G6P. PMID:109015

  19. Natural Progression of Canine Glycogen Storage Disease Type IIIa

    PubMed Central

    Brooks, Elizabeth D; Yi, Haiqing; Austin, Stephanie L; Thurberg, Beth L; Young, Sarah P; Fyfe, John C; Kishnani, Priya S; Sun, Baodong

    2016-01-01

    Glycogen storage disease type IIIa (GSD IIIa) is caused by a deficiency of glycogen debranching enzyme activity. Hepatomegaly, muscle degeneration, and hypoglycemia occur in human patients at an early age. Long-term complications include liver cirrhosis, hepatic adenomas, and generalized myopathy. A naturally occurring canine model of GSD IIIa that mimics the human disease has been described, with progressive liver disease and skeletal muscle damage likely due to excess glycogen deposition. In the current study, long-term follow-up of previously described GSD IIIa dogs until 32 mo of age (n = 4) and of family-owned GSD IIIa dogs until 11 to 12 y of age (n = 2) revealed that elevated concentrations of liver and muscle enzyme (AST, ALT, ALP, and creatine phosphokinase) decreased over time, consistent with hepatic cirrhosis and muscle fibrosis. Glycogen deposition in many skeletal muscles; the tongue, diaphragm, and heart; and the phrenic and sciatic nerves occurred also. Furthermore, the urinary biomarker Glc4, which has been described in many types of GSD, was first elevated and then decreased later in life. This urinary biomarker demonstrated a similar trend as AST and ALT in GSD IIIa dogs, indicating that Glc4 might be a less invasive biomarker of hepatocellular disease. Finally, the current study further demonstrates that the canine GSD IIIa model adheres to the clinical course in human patients with this disorder and is an appropriate model for developing novel therapies. PMID:26884409

  20. Acid Hydrolysis and Molecular Density of Phytoglycogen and Liver Glycogen Helps Understand the Bonding in Glycogen α (Composite) Particles

    PubMed Central

    Powell, Prudence O.; Sullivan, Mitchell A.; Sheehy, Joshua J.; Schulz, Benjamin L.; Warren, Frederick J.; Gilbert, Robert G.

    2015-01-01

    Phytoglycogen (from certain mutant plants) and animal glycogen are highly branched glucose polymers with similarities in structural features and molecular size range. Both appear to form composite α particles from smaller β particles. The molecular size distribution of liver glycogen is bimodal, with distinct α and β components, while that of phytoglycogen is monomodal. This study aims to enhance our understanding of the nature of the link between liver-glycogen β particles resulting in the formation of large α particles. It examines the time evolution of the size distribution of these molecules during acid hydrolysis, and the size dependence of the molecular density of both glucans. The monomodal distribution of phytoglycogen decreases uniformly in time with hydrolysis, while with glycogen, the large particles degrade significantly more quickly. The size dependence of the molecular density shows qualitatively different shapes for these two types of molecules. The data, combined with a quantitative model for the evolution of the distribution during degradation, suggest that the bonding between β into α particles is different between phytoglycogen and liver glycogen, with the formation of a glycosidic linkage for phytoglycogen and a covalent or strong non-covalent linkage, most probably involving a protein, for glycogen as most likely. This finding is of importance for diabetes, where α-particle structure is impaired. PMID:25799321

  1. Herniation of Duodenum into the Right Ventral Hepatic Peritoneal Cavity with Groove Formation at the Ventral Hepatic Surface in a 2-Week-Old Chicken

    PubMed Central

    HARIDY, Mohie; SASAKI, Jun; GORYO, Masanobu

    2013-01-01

    ABSTRACT Internal hernia in avian species is very rare. A necropsy of a 2-week-old SPF White Leghorn chicken revealed that a loop of the duodenum and part of the pancreas (4 × 2 × 1 cm) was protruding through the abnormal foramen (2.5 cm in diameter) in the right posthepatic septum into the right ventral hepatic peritoneal cavity. The herniated loop was located underneath the ventral hepatic surface, leaving a groove on the right hepatic lobe (2 × 1.5 × 0.4 cm). The part of the pancreas involved in the hernia was grossly enlarged. Microscopically, a zone of pressure atrophy of hepatic tissue was characterized by crowdedness of hepatocytes with pyknotic nuclei and faint eosinophilic cytoplasm and indistinct narrow sinusoids. The pancreas revealed hypertrophy of the acinar cells with an increase in the secretory granules and basophilic cytoplasm. This is the first report of duodenum herniation into the right ventral hepatic peritoneal cavity resulting in groove formation on the ventral hepatic surface in a 2-week-old chicken. PMID:23759688

  2. Glycogenotic hepatocellular carcinoma with glycogen-ground-glass hepatocytes: A heuristically highly relevant phenotype

    PubMed Central

    Bannasch, Peter

    2012-01-01

    Glycogenotic hepatocellular carcinoma (HCC) with glycogen-ground-glass hepatocytes has recently been described as an allegedly “novel variant” of HCC, but neither the historical background nor the heuristic relevance of this observation were put in perspective. In the present contribution, the most important findings in animal models and human beings related to the emergence and further evolution of excessively glycogen storing (glycogenotic) hepatocytes with and without ground glass features during neoplastic development have been summarized. Glycogenotic HCCs with glycogen-ground-glass hepatocytes represent highly differentiated neoplasms which contain subpopulations of cells phenotypically resembling those of certain types of preneoplastic hepatic foci and benign hepatocellular neoplasms. It is questionable whether the occurrence of glycogen-ground-glass hepatocytes in a glycogenotic HCC justifies its classification as a specific entity. The typical appearance of ground-glass hepatocytes is due to a hypertrophy of the smooth endoplasmic reticulum, which is usually associated with an excessive storage of glycogen and frequently also with an expression of the hepatitis B surface antigen. Sequential studies in animal models and observations in humans indicate that glycogen-ground-glass hepatocytes are a facultative, integral part of a characteristic cellular sequence commencing with focal hepatic glycogenosis potentially progressing to benign and malignant neoplasms. During this process highly differentiated glycogenotic cells including ground-glass hepatocytes are gradually transformed via various intermediate stages into poorly differentiated glycogen-poor, basophilic (ribosome-rich) cancer cells. Histochemical, microbiochemical, and molecular biochemical studies on focal hepatic glycogenosis and advanced preneoplastic and neoplastic lesions in tissue sections and laser-dissected specimens in rat and mouse models have provided compelling evidence for an early

  3. Deficient activity of dephosphophosphorylase kinase and accumulation of glycogen in the liver

    PubMed Central

    Hug, George; Schubert, William K.; Chuck, Gail

    1969-01-01

    Low activity of phosphorylase and increased concentration of glycogen were found in liver tissue from five children with asymptomatic hepatomegaly. In vitro activation of liver phosphorylase in these patients occurred at the rate of 10% or less of normal. Elimination of the defect by the addition of kinase that activates phosphorylase demonstrated the integrity of the phosphorylase enzyme and the deficient activity of dephophophosphorylase kinase. On the average, 60% of the phosphorylase enzyme of normal human liver was in the active form. Phosphorylase kinase of rabbit muscle activated phosphorylase of normal human liver to a final value that was significantly higher than the one obtained in the absence of muscle phosphorylase kinase. The ultrastructural examination of hepatic tissue from the five patients revealed increased amounts of glycogen. There was scarcity of endoplasmic reticulum. There was intercellular glycogen in continuity with the glycogen of the hepatocytes through breaks in their circumference. Lipid droplets with lucid areas in the form of needles and plates contained aggregates of glycogen. There were numerous lysosomes, some containing glycogen. Large vacuoles filled with glycogen and surrounded by a membrane were seen occasionally. The vacuoles might reflect the lysosomal pathway of glycogen degradation, since there was apparent fusion of such autophagic vacuoles with small vesicles resembling primary lysosomes. Images PMID:5774108

  4. Assignment of the gene encoding glycogen synthase (GYS) to human chromosome 19, band q13,3

    SciTech Connect

    Lehto, M. Helsinki Univ. ); Stoffel, M.; Espinosa, R. III; Beau, M.M. le; Bell, G.I. ); Groop, L. )

    1993-02-01

    The enzyme glycogen synthase (UDP glocose:glycogen 4-[alpha]-D-glucosyltransferase, EC 2.4.1.11) catalyzes the formation of glycogen from uridine diphosphate glucose (UPDG). Impaired activation of muscle glycogen synthase by insulin has been noted in patients with genetic risk of developing non-insulin-dependent diabets mellitus (NIDDM) and this may represent an early defect in the pathogenesis of this disorder. As such, glycogen synthase represents a candidate gene for contributing to genetic susceptibility. As a first step in studying the role of glycogen synthase in the genetics of NIDDM, we have isolated a cosmid encoding the human glycogen synthase gene (gene symbol GYS) and determined its chromosomal localization by fluorescence in situ hybridization. 4 refs., 1 fig.

  5. Dichloroacetate Stimulates Glycogen Accumulation in Primary Hepatocytes through an Insulin-Independent Mechanism

    SciTech Connect

    Lingohr, Melissa K.; Bull, Richard J.; Kato-Weinstein, Junko; Thrall, Brian D. )

    2002-01-01

    Dichloroacetate (DCA), a by-product of water chlorination, causes liver cancer in B6C3F1 mice. A hallmark response observed in mice exposed to carcinogenic doses of DCA is an accumulation of hepatic glycogen content. To distinguish whether the in vivo glycogenic effect of DCA was dependent on insulin and insulin signaling proteins, experiments were conducted in isolated hepatocytes where insulin concentrations could be controlled. In hepatocytes isolated from male B6C3F1 mice, DCA increased glycogen levels in a dose-related manner, independently of insulin. The accumulation of hepatocellular glycogen induced by DCA was not the result of decreased glycogenolysis, since DCA had no effect on the rate of glucagon-stimulated glycogen breakdown. Glycogen accumulation caused by DCA treatment was not hindered by inhibitors of extracellular-regulated protein kinase kinase (Erk1/2 kinase or MEK) or p70 kDa S6 protein kinase (p70(S6K)), but was completely blocked by the phosphatidylinositol 3-kinase (PI3K) inhibitors, LY294002 and wortmannin. Similarly, insulin-stimulated glycogen deposition was not influenced by the Erk1/2 kinase inhibitor, PD098509, or the p70(S6K) inhibitor, rapamycin. Unlike DCA-stimulated glycogen deposition, PI3K-inhibition only partially blocked the glycogenic effect of insulin. DCA did not cause phosphorylation of the downstream PI3K target protein, protein kinase B (PKB/Akt). The phosphorylation of PKB/Akt did not correlate to insulin-stimulated glycogenesis either. Similar to insulin, DCA in the medium decreased IR expression in isolated hepatocytes. The results indicate DCA increases hepatocellular glycogen accumulation through a PI3K-dependent mechanism that does not involve PKB/Akt and is, at least in part, different from the classical insulin-stimulated glycogenesis pathway. Somewhat surprisingly, insulin-stimulated glycogenesis also appears not to involve PKB/Akt in isolated murine hepatocytes.

  6. Link between Phosphate Starvation and Glycogen Metabolism in Corynebacterium glutamicum, Revealed by Metabolomics▿ †

    PubMed Central

    Woo, Han Min; Noack, Stephan; Seibold, Gerd M.; Willbold, Sabine; Eikmanns, Bernhard J.; Bott, Michael

    2010-01-01

    In this study, we analyzed the influence of phosphate (Pi) limitation on the metabolism of Corynebacterium glutamicum. Metabolite analysis by gas chromatography-time-of-flight (GC-TOF) mass spectrometry of cells cultivated in glucose minimal medium revealed a greatly increased maltose level under Pi limitation. As maltose formation could be linked to glycogen metabolism, the cellular glycogen content was determined. Unlike in cells grown under Pi excess, the glycogen level in Pi-limited cells remained high in the stationary phase. Surprisingly, even acetate-grown cells, which do not form glycogen under Pi excess, did so under Pi limitation and also retained it in stationary phase. Expression of pgm and glgC, encoding the first two enzymes of glycogen synthesis, phosphoglucomutase and ADP-glucose pyrophosphorylase, was found to be increased 6- and 3-fold under Pi limitation, respectively. Increased glycogen synthesis together with a decreased glycogen degradation might be responsible for the altered glycogen metabolism. Independent from these experimental results, flux balance analysis suggested that an increased carbon flux to glycogen is a solution for C. glutamicum to adapt carbon metabolism to limited Pi concentrations. PMID:20802079

  7. Genetics Home Reference: glycogen storage disease type IV

    MedlinePlus

    ... gene provides instructions for making the glycogen branching enzyme. This enzyme is involved in the production of glycogen , which ... to a shortage (deficiency) of the glycogen branching enzyme. As a result, glycogen is not formed properly. ...

  8. Glucagon-like peptide 1: a potent glycogenic hormone.

    PubMed

    Valverde, I; Morales, M; Clemente, F; López-Delgado, M I; Delgado, E; Perea, A; Villanueva-Peñacarrillo, M L

    1994-08-01

    GLP-1(7-36)amide is an insulinotropic peptide derived from the intestinal post-translational proglucagon process, the release of which is increased mainly after a carbohydrate meal; also, its anti-diabetogenic effect in normal and diabetic states has been reported. In this study, GLP-1(7-36)amide stimulates the formation of glycogen from glucose in isolated rat hepatocytes, such a glycogenic effect being achieved with physiological concentrations of the peptide. The GLP-1(7-36)amide-induced glycogenesis is abolished by glucagon, and it is accompanied by stimulation of the glycogen synthase alpha activity and by a decrease in the basal and glucagon-stimulated cyclic AMP content. These findings could explain, at least in part, the GLP-1(7-36)amide insulin-independent plasma glucose lowering effect. PMID:8050588

  9. FGF2 mediates hepatic progenitor cell formation during human pluripotent stem cell differentiation by inducing the WNT antagonist NKD1.

    PubMed

    Twaroski, Kirk; Mallanna, Sunil K; Jing, Ran; DiFurio, Francesca; Urick, Amanda; Duncan, Stephen A

    2015-12-01

    Fibroblast growth factors (FGFs) are required to specify hepatic fate within the definitive endoderm through activation of the FGF receptors (FGFRs). While the signaling pathways involved in hepatic specification are well understood, the mechanisms through which FGFs induce hepatic character within the endoderm are ill defined. Here we report the identification of genes whose expression is directly regulated by FGFR activity during the transition from endoderm to hepatic progenitor cell. The FGFR immediate early genes that were identified include those encoding transcription factors, growth factors, and signaling molecules. One of these immediate early genes encodes naked cuticle homolog 1 (NKD1), which is a repressor of canonical WNT (wingless-type MMTV integration site) signaling. We show that loss of NKD1 suppresses the formation of hepatic progenitor cells from human induced pluripotent stem cells and that this phenotype can be rescued by using a pharmacological antagonist of canonical WNT signaling. We conclude that FGF specifies hepatic fate at least in large part by inducing expression of NKD1 to transiently suppress the canonical WNT pathway. PMID:26637527

  10. FGF2 mediates hepatic progenitor cell formation during human pluripotent stem cell differentiation by inducing the WNT antagonist NKD1

    PubMed Central

    Twaroski, Kirk; Mallanna, Sunil K.; Jing, Ran; DiFurio, Francesca; Urick, Amanda; Duncan, Stephen A.

    2015-01-01

    Fibroblast growth factors (FGFs) are required to specify hepatic fate within the definitive endoderm through activation of the FGF receptors (FGFRs). While the signaling pathways involved in hepatic specification are well understood, the mechanisms through which FGFs induce hepatic character within the endoderm are ill defined. Here we report the identification of genes whose expression is directly regulated by FGFR activity during the transition from endoderm to hepatic progenitor cell. The FGFR immediate early genes that were identified include those encoding transcription factors, growth factors, and signaling molecules. One of these immediate early genes encodes naked cuticle homolog 1 (NKD1), which is a repressor of canonical WNT (wingless-type MMTV integration site) signaling. We show that loss of NKD1 suppresses the formation of hepatic progenitor cells from human induced pluripotent stem cells and that this phenotype can be rescued by using a pharmacological antagonist of canonical WNT signaling. We conclude that FGF specifies hepatic fate at least in large part by inducing expression of NKD1 to transiently suppress the canonical WNT pathway. PMID:26637527

  11. A Novel Pyridazinone Derivative Inhibits Hepatitis B Virus Replication by Inducing Genome-Free Capsid Formation

    PubMed Central

    Wang, Ya-Juan; Lu, Dong; Xu, Yi-Bin; Xing, Wei-Qiang; Tong, Xian-Kun; Wang, Gui-Feng; Feng, Chun-Lan; He, Pei-Lan; Zuo, Jian-Ping

    2015-01-01

    Here we first identified a novel pyridazinone derivative, compound 3711, as a nonnucleosidic hepatitis B virus (HBV) inhibitor in a cell model system. 3711 decreased extracellular HBV DNA levels by 50% (50% inhibitory concentration [IC50]) at 1.5 ± 0.2 μM and intracellular DNA levels at 1.9 ± 0.1 μM, which demonstrated antiviral activity at levels far below those associated with toxicity. Both the 3TC/ETV dually resistant L180M/M204I mutant and the adefovir (ADV)-resistant A181T/N236T mutant were as susceptible to 3711 as wild-type HBV. 3711 treatment induced the formation of genome-free capsids, a portion of which migrated faster on 1.8% native agarose gel. The induced genome-free capsids sedimented more slowly in isopycnic CsCl gradient centrifugation without significant morphological changes. 3711 treatment decreased levels of HBV DNA contained in both secreted enveloped virion and naked virus particles in supernatant. 3711 could interfere with capsid formation of the core protein (Cp) assembly domain. A Cp V124W mutant, which strengthens capsid interdimer interactions, recapitulated the effect of 3711 on capsid assembly. Pyridazinone derivative 3711, a novel chemical entity and HBV inhibitor, may provide a new opportunity to combat chronic HBV infection. PMID:26349829

  12. Hexokinase 2, Glycogen Synthase and Phosphorylase Play a Key Role in Muscle Glycogen Supercompensation

    PubMed Central

    Irimia, José M.; Rovira, Jordi; Nielsen, Jakob N.; Guerrero, Mario; Wojtaszewski, Jørgen F. P.; Cussó, Roser

    2012-01-01

    Background Glycogen-depleting exercise can lead to supercompensation of muscle glycogen stores, but the biochemical mechanisms of this phenomenon are still not completely understood. Methods Using chronic low-frequency stimulation (CLFS) as an exercise model, the tibialis anterior muscle of rabbits was stimulated for either 1 or 24 hours, inducing a reduction in glycogen of 90% and 50% respectively. Glycogen recovery was subsequently monitored during 24 hours of rest. Results In muscles stimulated for 1 hour, glycogen recovered basal levels during the rest period. However, in those stimulated for 24 hours, glycogen was supercompensated and its levels remained 50% higher than basal levels after 6 hours of rest, although the newly synthesized glycogen had fewer branches. This increase in glycogen correlated with an increase in hexokinase-2 expression and activity, a reduction in the glycogen phosphorylase activity ratio and an increase in the glycogen synthase activity ratio, due to dephosphorylation of site 3a, even in the presence of elevated glycogen stores. During supercompensation there was also an increase in 5′-AMP-activated protein kinase phosphorylation, correlating with a stable reduction in ATP and total purine nucleotide levels. Conclusions Glycogen supercompensation requires a coordinated chain of events at two levels in the context of decreased cell energy balance: First, an increase in the glucose phosphorylation capacity of the muscle and secondly, control of the enzymes directly involved in the synthesis and degradation of the glycogen molecule. However, supercompensated glycogen has fewer branches. PMID:22860128

  13. Multiple Glycogen-binding Sites in Eukaryotic Glycogen Synthase Are Required for High Catalytic Efficiency toward Glycogen

    SciTech Connect

    Baskaran, Sulochanadevi; Chikwana, Vimbai M.; Contreras, Christopher J.; Davis, Keri D.; Wilson, Wayne A.; DePaoli-Roach, Anna A.; Roach, Peter J.; Hurley, Thomas D.

    2012-12-10

    Glycogen synthase is a rate-limiting enzyme in the biosynthesis of glycogen and has an essential role in glucose homeostasis. The three-dimensional structures of yeast glycogen synthase (Gsy2p) complexed with maltooctaose identified four conserved maltodextrin-binding sites distributed across the surface of the enzyme. Site-1 is positioned on the N-terminal domain, site-2 and site-3 are present on the C-terminal domain, and site-4 is located in an interdomain cleft adjacent to the active site. Mutation of these surface sites decreased glycogen binding and catalytic efficiency toward glycogen. Mutations within site-1 and site-2 reduced the V{sub max}/S{sub 0.5} for glycogen by 40- and 70-fold, respectively. Combined mutation of site-1 and site-2 decreased the V{sub max}/S{sub 0.5} for glycogen by >3000-fold. Consistent with the in vitro data, glycogen accumulation in glycogen synthase-deficient yeast cells ({Delta}gsy1-gsy2) transformed with the site-1, site-2, combined site-1/site-2, or site-4 mutant form of Gsy2p was decreased by up to 40-fold. In contrast to the glycogen results, the ability to utilize maltooctaose as an in vitro substrate was unaffected in the site-2 mutant, moderately affected in the site-1 mutant, and almost completely abolished in the site-4 mutant. These data show that the ability to utilize maltooctaose as a substrate can be independent of the ability to utilize glycogen. Our data support the hypothesis that site-1 and site-2 provide a 'toehold mechanism,' keeping glycogen synthase tightly associated with the glycogen particle, whereas site-4 is more closely associated with positioning of the nonreducing end during catalysis.

  14. Hydrodynamic properties of 2-mercaptoethanol-modified glycogen.

    PubMed

    Geddes, R; Harvey, J D; Wills, P R

    1977-12-01

    Treatment of glycogen with 2-mercaptoethanol and iodoacetamide gives rise to a modified glycogen which resembles the original glycogen in its hydrodynamic behaviour but has a pronounced tendency to aggregate. The modified glycogen can be distinguished easily, by its diffusion coefficient, from glycogen degraded by more traditional methods of extraction. The 'fundamental' glycogen particle appears to be composed of two or three glycogen beta-particles linked by a single protein chain. PMID:598377

  15. Spheroid Formation and Evaluation of Hepatic Cells in a Three-Dimensional Culture Device

    PubMed Central

    Miyamoto, Yoshitaka; Ikeuchi, Masashi; Noguchi, Hirofumi; Yagi, Tohru; Hayashi, Shuji

    2015-01-01

    In drug discovery, it is very important to evaluate liver cells within an organism. Compared to 2D culture methods, the development of 3D culture techniques for liver cells has been successful in maintaining long-term liver functionality with the formation of a hepatic-specific structure. The key to performing drug testing is the establishment of a stable in vitro evaluation system. In this article, we report a Tapered Stencil for Cluster Culture (TASCL) device developed to create liver spheroids in vitro. The TASCL device will be applied as a toxicity evaluation system for drug discovery. The TASCL device was created with an overall size of 10 mm × 10 mm, containing 400 microwells with a top aperture (500 µm × 500 µm) and a bottom aperture (300 µm diameter circular) per microwell. We evaluated the formation, recovery, and size of HepG2 spheroids in the TASCL device. The formation and recovery were both nearly 100%, and the size of the HepG2 spheroids increased with an increase in the initial cell seeding density. There were no significant differences in the sizes of the spheroids among the microwells. In addition, the HepG2 spheroids obtained using the TASCL device were alive and produced albumin. The morphology of the HepG2 spheroids was investigated using FE-SEM. The spheroids in the microwells exhibited perfectly spherical aggregation. In this report, by adjusting the size of the microwells of the TASCL device, uniform HepG2 spheroids were created, and the device facilitated more precise measurements of the liver function per HepG2 spheroid. Our TASCL device will be useful for application as a toxicity evaluation system for drug testing. PMID:26858908

  16. Spheroid Formation and Evaluation of Hepatic Cells in a Three-Dimensional Culture Device.

    PubMed

    Miyamoto, Yoshitaka; Ikeuchi, Masashi; Noguchi, Hirofumi; Yagi, Tohru; Hayashi, Shuji

    2015-12-17

    In drug discovery, it is very important to evaluate liver cells within an organism. Compared to 2D culture methods, the development of 3D culture techniques for liver cells has been successful in maintaining long-term liver functionality with the formation of a hepatic-specific structure. The key to performing drug testing is the establishment of a stable in vitro evaluation system. In this article, we report a Tapered Stencil for Cluster Culture (TASCL) device developed to create liver spheroids in vitro. The TASCL device will be applied as a toxicity evaluation system for drug discovery. The TASCL device was created with an overall size of 10 mm × 10 mm, containing 400 microwells with a top aperture (500 µm × 500 µm) and a bottom aperture (300 µm diameter circular) per microwell. We evaluated the formation, recovery, and size of HepG2 spheroids in the TASCL device. The formation and recovery were both nearly 100%, and the size of the HepG2 spheroids increased with an increase in the initial cell seeding density. There were no significant differences in the sizes of the spheroids among the microwells. In addition, the HepG2 spheroids obtained using the TASCL device were alive and produced albumin. The morphology of the HepG2 spheroids was investigated using FE-SEM. The spheroids in the microwells exhibited perfectly spherical aggregation. In this report, by adjusting the size of the microwells of the TASCL device, uniform HepG2 spheroids were created, and the device facilitated more precise measurements of the liver function per HepG2 spheroid. Our TASCL device will be useful for application as a toxicity evaluation system for drug testing. PMID:26858908

  17. Brain glycogen decreases during prolonged exercise

    PubMed Central

    Matsui, Takashi; Soya, Shingo; Okamoto, Masahiro; Ichitani, Yukio; Kawanaka, Kentaro; Soya, Hideaki

    2011-01-01

    Abstract Brain glycogen could be a critical energy source for brain activity when the glucose supply from the blood is inadequate (hypoglycaemia). Although untested, it is hypothesized that during prolonged exhaustive exercise that induces hypoglycaemia and muscular glycogen depletion, the resultant hypoglycaemia may cause a decrease in brain glycogen. Here, we tested this hypothesis and also investigated the possible involvement of brain monoamines with the reduced levels of brain glycogen. For this purpose, we exercised male Wistar rats on a treadmill for different durations (30–120 min) at moderate intensity (20 m min−1) and measured their brain glycogen levels using high-power microwave irradiation (10 kW). At the end of 30 and 60 min of running, the brain glycogen levels remained unchanged from resting levels, but liver and muscle glycogen decreased. After 120 min of running, the glycogen levels decreased significantly by ∼37–60% in five discrete brain loci (the cerebellum 60%, cortex 48%, hippocampus 43%, brainstem 37% and hypothalamus 34%) compared to those of the sedentary control. The brain glycogen levels in all five regions after running were positively correlated with the respective blood and brain glucose levels. Further, in the cortex, the levels of methoxyhydroxyphenylglycol (MHPG) and 5-hydroxyindoleacetic acid (5-HIAA), potential involved in degradation of the brain glycogen, increased during prolonged exercise and negatively correlated with the glycogen levels. These results support the hypothesis that brain glycogen could decrease with prolonged exhaustive exercise. Increased monoamines together with hypoglycaemia should be associated with the development of decreased brain glycogen, suggesting a new clue towards the understanding of central fatigue during prolonged exercise. PMID:21521757

  18. Revisiting Glycogen Content in the Human Brain.

    PubMed

    Öz, Gülin; DiNuzzo, Mauro; Kumar, Anjali; Moheet, Amir; Seaquist, Elizabeth R

    2015-12-01

    Glycogen provides an important glucose reservoir in the brain since the concentration of glucosyl units stored in glycogen is several fold higher than free glucose available in brain tissue. We have previously reported 3-4 µmol/g brain glycogen content using in vivo (13)C magnetic resonance spectroscopy (MRS) in conjunction with [1-(13)C]glucose administration in healthy humans, while higher levels were reported in the rodent brain. Due to the slow turnover of bulk brain glycogen in humans, complete turnover of the glycogen pool, estimated to take 3-5 days, was not observed in these prior studies. In an attempt to reach complete turnover and thereby steady state (13)C labeling in glycogen, here we administered [1-(13)C]glucose to healthy volunteers for 80 h. To eliminate any net glycogen synthesis during this period and thereby achieve an accurate estimate of glycogen concentration, volunteers were maintained at euglycemic blood glucose levels during [1-(13)C]glucose administration and (13)C-glycogen levels in the occipital lobe were measured by (13)C MRS approximately every 12 h. Finally, we fitted the data with a biophysical model that was recently developed to take into account the tiered structure of the glycogen molecule and additionally incorporated blood glucose levels and isotopic enrichments as input function in the model. We obtained excellent fits of the model to the (13)C-glycogen data, and glycogen content in the healthy human brain tissue was found to be 7.8 ± 0.3 µmol/g, a value substantially higher than previous estimates of glycogen content in the human brain. PMID:26202425

  19. Studies in tissue glycogen in acute stress.

    PubMed

    De, A K; Dey, C; Debnath, P K

    1978-01-01

    The glycogen was estimated in liver, cardiac and skeletal muscles during the recovery period after electro-shock. The supercompensation in the level of glycogen was observed in cardiac and skeletal muscles at 1 1/2 and 5 hrs respectively during the recovery period, after electro-shock. The liver glycogen level was lower than the control value after electro-shock at least upto 5 hrs of recovery period. Further, the glycogen level was observed to be minimum when the ventricular glycogen showed its supercompensation at 1 1/2 hr of recovery period. The glycogen level of those three tissues returned to control level after 24 hrs of electro-shock. PMID:567192

  20. The inflammasome in alcoholic hepatitis: its relationship with Mallory-Denk body formation

    PubMed Central

    Peng, Yue; French, Barbara A.; Tillman, Brittany; Morgan, T; French, Samuel W.

    2014-01-01

    Recent studies indicate that the inflammasome activation plays important roles in pathogenesis of alcoholic hepatitis (AH). Nod-like receptor protein 3 (NLRP3) is a key component of the macromolecular complex so called the inflammasome that trigger caspase 1-dependent maturation of the precursors of IL-1β and IL-18 cytokines. It is also known that the adaptor proteins including apoptosis-associated speck-like protein containing CARD (ASC) and the mitochondrial antiviral signaling protein (MAVS) are necessary for NLRP3-dependent inflammasome function. Steatohepatitis frequently includes Mallory-Denk body (MDB) formation. In the case of alcoholic steatohepatitis, MDB formation occurs in 80% of biopsies (French 1981; French 1981). While previous studies have focused on in vitro cell lines and mouse models, we are the first group to investigate inflammasome activation in AH liver biopsy specimen and correlate it with MDB formation. Expression of NOD1, NLRP3, ASC, NAIP, MAVS, Caspase 1, IL-1β, IL-18, and other inflammatory components including IL-6, IL-10, TNF-α, IFN-γ, STAT3, p65 was measured in three to eight formalin-fixed paraffin-embedded AH specimens and control normal liver specimens by immunofluorescence staining and quantified by immunofluorescence intensity. The specimens were double stained with ubiquitin to demonstrate the relationship between inflammasome activation and MDB formation. MAVS, caspase1, IL-18, TNF-α showed increases in expression in AH compared to the controls (p<0.05), and NAIP expression markedly increased in AH compared to the controls (p<0.01). There was a trend that levels of NLRP3, ASC, caspase1, IL-18, IL-10, and p65 expression correlated with the number of MDBs found in the same field of measurement (correlation coefficients were between 0.62 to 0.93, p<0.05). Our results demonstrate the activation of the inflammasome in AH and suggest that MDB could be an indicator of the extent of inflammasome activation. PMID:25149528

  1. The inflammasome in alcoholic hepatitis: Its relationship with Mallory-Denk body formation.

    PubMed

    Peng, Yue; French, Barbara A; Tillman, Brittany; Morgan, Timothy R; French, Samuel W

    2014-10-01

    Recent studies indicate that the inflammasome activation plays important roles in the pathogenesis of alcoholic hepatitis (AH). Nod-like receptor protein 3 (NLRP3) is a key component of the macromolecular complex that is so called the inflammasome that triggers caspase 1-dependent maturation of the precursors of IL-1β and IL-18 cytokines. It is also known that the adaptor proteins including apoptosis-associated speck-like protein containing CARD (ASC) and the mitochondrial antiviral signaling protein (MAVS) are necessary for NLRP3-dependent inflammasome function. Steatohepatitis frequently includes Mallory-Denk body (MDB) formation. In the case of alcoholic steatohepatitis, MDB formation occurs in 80% of biopsies (French 1981; French 1981). While previous studies have focused on in vitro cell lines and mouse models, we are the first group to investigate inflammasome activation in AH liver biopsy specimen and correlate it with MDB formation. Expression of NOD1, NLRP3, ASC, NAIP, MAVS, caspase 1, IL-1β, IL-18, and other inflammatory components including IL-6, IL-10, TNF-α, IFN-γ, STAT3, and p65 was measured in three to eight formalin-fixed paraffin-embedded AH specimens and control normal liver specimens by immunofluorescence staining and quantified by immunofluorescence intensity. The specimens were double stained with ubiquitin to demonstrate the relationship between inflammasome activation and MDB formation. MAVS, caspase1, IL-18, and TNF-α showed increases in expression in AH compared to the controls (p<0.05), and NAIP expression markedly increased in AH compared to the controls (p<0.01). There was a trend that levels of NLRP3, ASC, caspase1, IL-18, IL-10, and p65 expression correlated with the number of MDBs found in the same field of measurement (correlation coefficients were between 0.62 and 0.93, p<0.05). Our results demonstrate the activation of the inflammasome in AH and suggest that MDB could be an indicator of the extent of inflammasome activation

  2. Glycogen: the forgotten cerebral energy store.

    PubMed

    Gruetter, Rolf

    2003-10-15

    The brain contains a significant amount of glycogen that is an order of magnitude smaller than that in muscle, but several-fold higher than the cerebral glucose content. Although the precise role of brain glycogen to date is unknown, it seems affected by focal activation, neurotransmitters, and overall electrical activity and hormones. Based on its relatively low concentration, the role of brain glycogen as a significant energy store has been discounted. This work reviews recent experimental evidence that brain glycogen is an important reserve of glucose equivalents: (1) glial glycogen can provide the majority of the glucose supply deficit during hypoglycemia for more than 100 min, consistent with the proposal that glial lactate is a fuel for neurons; (2) glycogen concentrations may be as high as 10 micromol/g, substantially higher than was thought previously; (3) glucose cycling in and out of glycogen amounts to approximately 1% of the cerebral metabolic rate of glucose (CMRglc) in human and rat brain, amounting to an effective stability of glycogen in the resting awake brain during euglycemia and hyperglycemia, (4) brain glycogen metabolism/concentrations are insulin/glucose sensitive; and (5) after a single episode of hypoglycemia, brain glycogen levels rebound to levels that exceed the pre-hypoglycemic concentrations (supercompensation). This experimental evidence supports the proposal that brain glycogen may be involved in the development of diabetes complications, specifically impaired glucose sensing (hypoglycemia unawareness) observed clinically in some diabetes patients under insulin treatment. It is proposed further that brain glycogen becomes important in any metabolic state where supply transiently cannot meet demand, such conditions that could occur during prolonged focal activation, sleep deprivation, seizures, and mild hypoxia. PMID:14515346

  3. Glycogen-lead relationship in the earthworm Dendrobaena rubida from a heavy metal site.

    PubMed

    Richards, K S; Ireland, M P

    1978-06-01

    Control individuals contained no lead in the chloragocytes but high alpha-glycogen rosette reserves. Starvation of contaminated earthworms for 4d caused a lead loss and the chlorgocytes possessed fewer debris vesicles than those of unstarved worms, suggesting that the debris vesicles may be the route for at least some of the lead loss. No glycogen deposits were observed in the chloragocytes of starved or unstarved earthworms from contaminated soil. Maintenance of contaminated earthworms in potting compost caused lead losses similar to those sustained by starvation, but the chloragocyte cytoplasm possessed beta-glycogen reserves. Specimens maintained in lead-spiked potting compost showed lead levels similar to those of earthworms taken directly from contaminated soil. No beta-glycogen accumulations were observed under this enriched regime. Although the possible interference of lead in carbohydrate metabolism is discussed, the results do not wholly support metabolic inhibition by lead. It is hypothesised that lead sequestration is energy-demanding and that in the absence of an energy-rich diet glycogen stores fail to accumulate. In the presence of an organic-rich medium, elevated lead levels preclude glycogen formation, because of the high sequestration-demand, but at lower lead levels beta-glycogen deposits occur if a high organic diet is available. PMID:659270

  4. Inhibition of bacterial cell wall-induced leukocyte recruitment and hepatic granuloma formation by TGF-beta gene transfer.

    PubMed

    Song, X; Zeng, L; Pilo, C M; Zagorski, J; Wahl, S M

    1999-10-01

    Intraperitoneal injection of streptococcal cell walls (SCW) into Lewis rats results in dissemination of SCW to the liver, spleen, bone marrow, and peripheral joints. The uptake of SCW by Kupffer cells in the liver initiates a chain of events largely mediated by T lymphocytes and macrophages. Local synthesis and secretion of cytokines and growth factors in response to the persistent SCW lead to the evolution and maintenance of a chronic T cell-dependent granulomatous response and result in granuloma formation and irreversible hepatic fibrosis. In an attempt to impede the development of the chronic granulomatous lesions in the liver, we injected a plasmid DNA encoding TGF-beta 1 i.m. to the SCW animals to determine the effect of TGF-beta 1 gene transfer on the course of liver inflammation and fibrosis. A single injection of plasmid DNA encoding TGF-beta 1 resulted in virtual abolition of the development of the SCW-induced hepatic granuloma formation and matrix expansion. TGF-beta 1 DNA not only reduced key proinflammatory cytokines including TNF-alpha, IL-1 beta, IFN-gamma, and IL-18, but also inhibited both CXC and CC chemokine production, thereby blocking inflammatory cell recruitment and accumulation in the liver. Moreover, TGF-beta 1 gene delivery inhibited its own expression in the liver tissue, which is otherwise up-regulated in SCW-injected animals. Our study suggests that TGF-beta 1 gene transfer suppresses hepatic granuloma formation by blocking the recruitment of inflammatory cells to the liver, and thus may provide a new approach to the control of hepatic granulomatous and fibrotic diseases. PMID:10491005

  5. Genetics Home Reference: glycogen storage disease type VII

    MedlinePlus

    ... Health Conditions glycogen storage disease type VII glycogen storage disease type VII Enable Javascript to view the ... Download PDF Open All Close All Description Glycogen storage disease type VII (GSDVII) is an inherited disorder ...

  6. ATP Depletion, a Possible Role in the Pathogenesis of Hyperuricemia in Glycogen Storage Disease Type I

    PubMed Central

    Greene, Harry L.; Wilson, Frederick A.; Hefferan, Patrick; Terry, Annie B.; Moran, Jose Roberto; Slonim, Alfred E.; Claus, Thomas H.; Burr, Ian M.

    1978-01-01

    Other investigators have shown that fructose infusion in normal man and rats acutely depletes hepatic ATP and Pi and increases the rate of uric acid formation by the degradation of preformed nucleotides. We postulated that a similar mechanism of ATP depletion might be present in patients with glucose-6-phosphatase deficiency (GSD-I) as a result of ATP consumption during glycogenolysis and resulting excess glycolysis. The postulate was tested by measurement of: (a) hepatic content of ATP, glycogen, phosphorylated sugars, and phosphorylase activities before and after increasing glycolysis by glucagon infusion and (b) plasma urate levels and urate excretion before and after therapy designed to maintain blood glucose levels above 70 mg/dl and thus prevent excess glycogenolysis and glycolysis. Glucagon infusion in seven patients with GSD-I caused a decrease in hepatic ATP from 2.25 ± 0.09 to 0.73 ± 0.06 μmol/g liver (P <0.01), within 5 min, persisting in one patient to 20 min (1.3 μmol/g). Three patients with GSD other than GSD-I (controls), and 10 normal rats, showed no change in ATP levels after glucagon infusion. Glucagon caused an increase in hepatic phosphorylase activity from 163 ± 21 to 311 ± 17 μmol/min per g protein (P <0.01), and a decrease in glycogen content from 8.96 ± 0.51 to 6.68 ± 0.38% weight (P <0.01). Hepatic content of phosphorylated hexoses measured in two patients, showed the following mean increases in response to glucagon; glucose-6-phosphate (from 0.25 to 0.98 μmol/g liver), fructose-6-phosphate (from 0.17 to 0.45 μmol/g liver), and fructose-1,6-diphosphate (from 0.09 to 1.28 μmol/g) within 5 min. These changes, except for glucose-6-phosphate, returned toward preinfusion levels within 20 min. Treatment consisted of continuous intragastric feedings of a high glucose dietary mixture. Such treatment increased blood glucose from a mean level of 62 (range 28-96) to 86 (range 71-143) mg/dl (P <0.02), decreased plasma glucagon from a mean

  7. Effect of oat bran on time to exhaustion, glycogen content and serum cytokine profile following exhaustive exercise

    PubMed Central

    2010-01-01

    The aim of this study was to evaluate the effect of oat bran supplementation on time to exhaustion, glycogen stores and cytokines in rats submitted to training. The animals were divided into 3 groups: sedentary control group (C), an exercise group that received a control chow (EX) and an exercise group that received a chow supplemented with oat bran (EX-O). Exercised groups were submitted to an eight weeks swimming training protocol. In the last training session, the animals performed exercise to exhaustion, (e.g. incapable to continue the exercise). After the euthanasia of the animals, blood, muscle and hepatic tissue were collected. Plasma cytokines and corticosterone were evaluated. Glycogen concentrations was measured in the soleus and gastrocnemius muscles, and liver. Glycogen synthetase-α gene expression was evaluated in the soleus muscle. Statistical analysis was performed using a factorial ANOVA. Time to exhaustion of the EX-O group was 20% higher (515 ± 3 minutes) when compared with EX group (425 ± 3 minutes) (p = 0.034). For hepatic glycogen, the EX-O group had a 67% higher concentrations when compared with EX (p = 0.022). In the soleus muscle, EX-O group presented a 59.4% higher glycogen concentrations when compared with EX group (p = 0.021). TNF-α was decreased, IL-6, IL-10 and corticosterone increased after exercise, and EX-O presented lower levels of IL-6, IL-10 and corticosterone levels in comparison with EX group. It was concluded that the chow rich in oat bran increase muscle and hepatic glycogen concentrations. The higher glycogen storage may improve endurance performance during training and competitions, and a lower post-exercise inflammatory response can accelerate recovery. PMID:20955601

  8. Effect of oat bran on time to exhaustion, glycogen content and serum cytokine profile following exhaustive exercise.

    PubMed

    Donatto, Felipe F; Prestes, Jonato; Frollini, Anelena B; Palanch, Adrianne C; Verlengia, Rozangela; Cavaglieri, Claudia Regina

    2010-01-01

    The aim of this study was to evaluate the effect of oat bran supplementation on time to exhaustion, glycogen stores and cytokines in rats submitted to training. The animals were divided into 3 groups: sedentary control group (C), an exercise group that received a control chow (EX) and an exercise group that received a chow supplemented with oat bran (EX-O). Exercised groups were submitted to an eight weeks swimming training protocol. In the last training session, the animals performed exercise to exhaustion, (e.g. incapable to continue the exercise). After the euthanasia of the animals, blood, muscle and hepatic tissue were collected. Plasma cytokines and corticosterone were evaluated. Glycogen concentrations was measured in the soleus and gastrocnemius muscles, and liver. Glycogen synthetase-α gene expression was evaluated in the soleus muscle. Statistical analysis was performed using a factorial ANOVA. Time to exhaustion of the EX-O group was 20% higher (515 ± 3 minutes) when compared with EX group (425 ± 3 minutes) (p = 0.034). For hepatic glycogen, the EX-O group had a 67% higher concentrations when compared with EX (p = 0.022). In the soleus muscle, EX-O group presented a 59.4% higher glycogen concentrations when compared with EX group (p = 0.021). TNF-α was decreased, IL-6, IL-10 and corticosterone increased after exercise, and EX-O presented lower levels of IL-6, IL-10 and corticosterone levels in comparison with EX group. It was concluded that the chow rich in oat bran increase muscle and hepatic glycogen concentrations. The higher glycogen storage may improve endurance performance during training and competitions, and a lower post-exercise inflammatory response can accelerate recovery. PMID:20955601

  9. Glucose and glycogen metabolism in erythrocytes from normal and glycogen storage disease type III subjects

    PubMed Central

    Moses, Shimon W.; Chayoth, Reuben; Levin, Stanley; Lazarovitz, Ela; Rubinstein, David

    1968-01-01

    Active glycogen metabolism has been demonstrated in both normal and glycogen-rich erythrocytes taken from patients with type III glycogen storage disease. Activity of all enzymes catalyzing the reactions required for the synthesis and degradation of glycogen have been demonstrated in the mature erythrocytes. Uniformly labeled glucose-14C is incorporated into glycogen in intact cells of both types during incubation. Replacement of the glucose-14C by unlabeled glucose in the medium resulted in a significant loss of radioactivity from cellular glycogen. In the absence of the substrate a progressive shortening of outer branches occurred during incubation of intact glucogen-rich cells. Using cells from patients with type III glycogen storage disease, which have sufficient glycogen content to be analyzed by β-amylolysis, we demonstrated that the glucosyl units are first incorporated in the outer tiers, then transferred to the core where they tend to accumulate due to the absence of amylo-1,6-glucosidase. The glycogen-rich cells have a more rapid rate of glucose utilization upon incubation which is not reflected by a higher lactate production. The increased rate of glucose utilization did not result from an increased rate of glucose incorporation into glycogen in affected cells. The rate of 14CO2 production from glucose-1-14C during incubation was not significantly different in the two types of cells unless methylene blue was added as an electron acceptor, in which case the glycogen-rich cells oxidized glucose to CO2 more rapidly. PMID:5240360

  10. Brain glycogen supercompensation following exhaustive exercise.

    PubMed

    Matsui, Takashi; Ishikawa, Taro; Ito, Hitoshi; Okamoto, Masahiro; Inoue, Koshiro; Lee, Min-Chul; Fujikawa, Takahiko; Ichitani, Yukio; Kawanaka, Kentaro; Soya, Hideaki

    2012-02-01

    Brain glycogen localized in astrocytes, a critical energy source for neurons, decreases during prolonged exhaustive exercise with hypoglycaemia. However, it is uncertain whether exhaustive exercise induces glycogen supercompensation in the brain as in skeletal muscle. To explore this question, we exercised adult male rats to exhaustion at moderate intensity (20 m min(-1)) by treadmill, and quantified glycogen levels in several brain loci and skeletal muscles using a high-power (10 kW) microwave irradiation method as a gold standard. Skeletal muscle glycogen was depleted by 82-90% with exhaustive exercise, and supercompensated by 43-46% at 24 h after exercise. Brain glycogen levels decreased by 50-64% with exhaustive exercise, and supercompensated by 29-63% (whole brain 46%, cortex 60%, hippocampus 33%, hypothalamus 29%, cerebellum 63% and brainstem 49%) at 6 h after exercise. The brain glycogen supercompensation rates after exercise positively correlated with their decrease rates during exercise. We also observed that cortical and hippocampal glycogen supercompensation were sustained until 24 h after exercise (long-lasting supercompensation), and their basal glycogen levels increased with 4 weeks of exercise training (60 min day(-1) at 20 m min(-1)). These results support the hypothesis that, like the effect in skeletal muscles, glycogen supercompensation also occurs in the brain following exhaustive exercise, and the extent of supercompensation is dependent on that of glycogen decrease during exercise across brain regions. However, supercompensation in the brain preceded that of skeletal muscles. Further, the long-lasting supercompensation of the cortex and hippocampus is probably a prerequisite for their training adaptation (increased basal levels), probably to meet the increased energy demands of the brain in exercising animals. PMID:22063629

  11. Activation of glycolysis and apoptosis in glycogen storage disease type Ia.

    PubMed

    Sun, Baodong; Li, Songtao; Yang, Liu; Damodaran, Tirupapuliyur; Desai, Dev; Diehl, Anna Mae; Alzate, Oscar; Koeberl, Dwight D

    2009-08-01

    The deficiency of glucose-6-phosphatase (G6Pase) underlies glycogen storage disease type Ia (GSD-Ia, von Gierke disease; MIM 232200), an autosomal recessive disorder of metabolism associated with life-threatening hypoglycemia, growth retardation, renal failure, hepatic adenomas, and hepatocellular carcinoma. Liver involvement includes the massive accumulation of glycogen and lipids due to accumulated glucose-6-phosphate and glycolytic intermediates. Proteomic analysis revealed elevations in glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and other enzymes involved in glycolysis. GAPDH was markedly increased in murine G6Pase-deficient hepatocytes. The moonlighting role of GAPDH includes increasing apoptosis, which was demonstrated by increased TUNEL assay positivity and caspase 3 activation in the murine GSD-Ia liver. These analyses of hepatic involvement in GSD-Ia mice have implicated the induction of apoptosis in the pathobiology of GSD-Ia. PMID:19419892

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

    SciTech Connect

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

    1988-03-01

    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-/sup 3/H,U-/sup 14/C)glucose into liver glycogen. Labeled glucose was injected into the portal vein at the end of meal-feeding. The ratio of /sup 3/H//sup 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 (/sup 3/H) and (/sup 14/C)-glycogen in rats infused with (3-/sup 3/H,U-/sup 14/C)glucose. No significant difference was found between the RSA of (/sup 3/H)glycogen and (/sup 14/C)glycogen, indicating further that the pathway for glycogen synthesis in liver from exogenous glucose is from the direct pathway.

  13. Mechanism of hepatic megamitochondria formation by ammonia derivatives. Correlation between structure of chemicals and their ability to induce the formation of megamitochondria.

    PubMed

    Wakabayashi, T; Horiuchi, M; Sakaguchi, M; Misawa, K; Onda, H; Iijima, M; Allmann, D W

    1984-09-01

    Correlation between the chemical structure and the ability to induce hepatic megamitochondria formation was studied by feeding mice and rats diets containing a wide spectrum of ammonia derivatives. Ammonia derivatives with electron-releasing groups, such as hydrazine, phenylhydrazine, hydroxylamine and aniline were effective in inducing megamitochondria. Ammonia derivatives with electron-withdrawing groups, such as formamide, sulfamic acid, acetamide were ineffective in inducing megamitochondria. Inducibility of ammonia derivatives with electron-releasing groups plus electron-withdrawing groups for the megamitochondria formation was dependent upon nucleophilicity of the chemical: 2,4-dinitrophenylhydrazine induced megamitochondria, while acetanilide did not induce megamitochondria. The megamitochondria formation induced by ammonia derivatives was a reversible process. Freeze-fracture studies on megamitochondria indicated that megamitochondria were formed by the fusion of adjacent mitochondria. Phosphorylating capacity of megamitochondria (hydrazine-induced megamitochondria, for example) were normal despite morphological changes. These data might suggest that the nucleophilicity of chemicals plays a key role in the induction of hepatic megamitochondria. These data might also suggest that the phenomenon is an adaptive process to changes of intracellular milieu. PMID:6468403

  14. An Aptamer against the Matrix Binding Domain on the Hepatitis B Virus Capsid Impairs Virion Formation

    PubMed Central

    Orabi, Ahmed; Bieringer, Maria; Geerlof, Arie

    2015-01-01

    ABSTRACT The hepatitis B virus (HBV) particle is an icosahedral nucleocapsid surrounded by a lipid envelope containing viral surface proteins. A small domain (matrix domain [MD]) in the large surface protein L and a narrow region (matrix binding domain [MBD]) including isoleucine 126 on the capsid surface have been mapped, in which point mutations such as core I126A specifically blocked nucleocapsid envelopment. It is possible that the two domains interact with each other during virion morphogenesis. By the systematic evolution of ligands by exponential enrichment (SELEX) method, we evolved DNA aptamers from an oligonucleotide library binding to purified recombinant capsids but not binding to the corresponding I126A mutant capsids. Aptamers bound to capsids were separated from unbound molecules by filtration. After 13 rounds of selections and amplifications, 16 different aptamers were found among 73 clones. The four most frequent aptamers represented more than 50% of the clones. The main aptamer, AO-01 (13 clones, 18%), showed the lowest dissociation constant (Kd) of 180 ± 82 nM for capsid binding among the four molecules. Its Kd for I126A capsids was 1,306 ± 503 nM. Cotransfection of Huh7 cells with AO-01 and an HBV genomic construct resulted in 47% inhibition of virion production at 3 days posttransfection, but there was no inhibition by cotransfection of an aptamer with a random sequence. The half-life of AO-01 in cells was 2 h, which might explain the incomplete inhibition. The results support the importance of the MBD for nucleocapsid envelopment. Inhibiting the MD-MBD interaction with a low-molecular-weight substance might represent a new approach for an antiviral therapy. IMPORTANCE Approximately 240 million people are persistently infected with HBV. To date, antiviral therapies depend on a single target, the viral reverse transcriptase. Future additional targets could be viral protein-protein interactions. We selected a 55-base-long single-stranded DNA

  15. [Role of HLA phenotype in the formation of chronic hepatitis C virus infection].

    PubMed

    Bondarenko, A L; Baramzina, S V

    2002-01-01

    Clinical, biochemical and immunological parameters depending on HLA-phenotypic features were examined in 107 patients aged 18-78 years with chronic hepatitis C virus (HCV) infection. Clinical and biochemical manifestations (asthenic, pain and cytolytic syndromes, hepatomegalia, hyperbilirubinemia, hypoprothrombin- and proteinemia), observed in hepatitis C, were more pronounced in patients having HLA-A30, B35, B41, Cw2, A1-B35, A9-B8. The carriers of B8 and B35 antigens were found to have inadequate immune response in HCV infection, manifested by progressive chronic process in the liver and the development of cirrhosis in patients with such specificity. PMID:12043154

  16. Glycogen metabolism in the rat retina.

    PubMed

    Coffe, Víctor; Carbajal, Raymundo C; Salceda, Rocío

    2004-02-01

    It has been reported that glycogen levels in retina vary with retinal vascularization. However, the electrical activity of isolated retina depends on glucose supply, suggesting that it does not contain energetic reserves. We determined glycogen levels and pyruvate and lactate production under various conditions in isolated retina. Ex vivo retinas from light- and dark-adapted rats showed values of 44 +/- 0.3 and 19.5 +/- 0.4 nmol glucosyl residues/mg protein, respectively. The glycogen content of retinas from light-adapted animals was reduced by 50% when they were transferred to darkness. Glycogen levels were low in retinas incubated in glucose-free media and increased in the presence of glucose. The highest glycogen values were found in media containing 20 mm of glucose. A rapid increase in lactate production was observed in the presence of glucose. Surprisingly, glycogen levels were the lowest and lactate production was also very low in the presence of 30 mm glucose. Our results suggest that glycogen can be used as an immediate accessible energy reserve in retina. We speculate on the possibility that gluconeogenesis may play a protective role by removal of lactic acid. PMID:14756809

  17. Targeting glycogen metabolism in bladder cancer

    PubMed Central

    Lew, Carolyn Ritterson; Guin, Sunny; Theodorescu, Dan

    2015-01-01

    Metabolism has been a heavily investigated topic in cancer research for the past decade. Although the role of aerobic glycolysis (the Warburg effect) in cancer has been extensively studied, abnormalities in other metabolic pathways are only just being understood in cancer. One such pathway is glycogen metabolism; its involvement in cancer development, particularly in urothelial malignancies, and possible ways of exploiting aberrations in this process for treatment are currently being studied. New research shows that the glycogen debranching enzyme amylo-α-1,6-glucosidase, 4-α-glucanotransferase (AGL) is a novel tumour suppressor in bladder cancer. Loss of AGL leads to rapid proliferation of bladder cancer cells. Another enzyme involved in glycogen debranching, glycogen phosphorylase, has been shown to be a tumour promoter in cancer, including in prostate cancer. Studies demonstrate that bladder cancer cells in which AGL expression is lost are more metabolically active than cells with intact AGL expression, and these cells are more sensitive to inhibition of both glycolysis and glycine synthesis—two targetable pathways. As a tumour promoter and enzyme, glycogen phosphorylase can be directly targeted, and preclinical inhibitor studies are promising. However, few of these glycogen phosphorylase inhibitors have been tested for cancer treatment in the clinical setting. Several possible limitations to the targeting of AGL and glycogen phosphorylase might also exist. PMID:26032551

  18. Biochemical Titration of Glycogen In vitro

    PubMed Central

    Pelletier, Joffrey; Bellot, Grégory; Pouysségur, Jacques; Mazure, Nathalie M.

    2013-01-01

    Glycogen is the main energetic polymer of glucose in vertebrate animals and plays a crucial role in whole body metabolism as well as in cellular metabolism. Many methods to detect glycogen already exist but only a few are quantitative. We describe here a method using the Abcam Glycogen assay kit, which is based on specific degradation of glycogen to glucose by glucoamylase. Glucose is then specifically oxidized to a product that reacts with the OxiRed probe to produce fluorescence. Titration is accurate, sensitive and can be achieved on cell extracts or tissue sections. However, in contrast to other techniques, it does not give information about the distribution of glycogen in the cell. As an example of this technique, we describe here the titration of glycogen in two cell lines, Chinese hamster lung fibroblast CCL39 and human colon carcinoma LS174, incubated in normoxia (21% O2) versus hypoxia (1% O2). We hypothesized that hypoxia is a signal that prepares cells to synthesize and store glycogen in order to survive1. PMID:24300406

  19. Polyprotein-Driven Formation of Two Interdependent Sets of Complexes Supporting Hepatitis C Virus Genome Replication

    PubMed Central

    Gomes, Rafael G. B.; Isken, Olaf; Tautz, Norbert; McLauchlan, John

    2015-01-01

    ABSTRACT Hepatitis C virus (HCV) requires proteins from the NS3-NS5B polyprotein to create a replicase unit for replication of its genome. The replicase proteins form membranous compartments in cells to facilitate replication, but little is known about their functional organization within these structures. We recently reported on intragenomic replicons, bicistronic viral transcripts expressing an authentic replicase from open reading frame 2 (ORF2) and a second duplicate nonstructural (NS) polyprotein from ORF1. Using these constructs and other methods, we have assessed the polyprotein requirements for rescue of different lethal point mutations across NS3-5B. Mutations readily tractable to rescue broadly fell into two groupings: those requiring expression of a minimum NS3-5A and those requiring expression of a minimum NS3-5B polyprotein. A cis-acting mutation that blocked NS3 helicase activity, T1299A, was tolerated when introduced into either ORF within the intragenomic replicon, but unlike many other mutations required the other ORF to express a functional NS3-5B. Three mutations were identified as more refractile to rescue: one that blocked cleavage of the NS4B5A boundary (S1977P), another in the NS3 helicase (K1240N), and a third in NS4A (V1665G). Introduced into ORF1, these exhibited a dominant negative phenotype, but with K1240N inhibiting replication as a minimum NS3-5A polyprotein whereas V1665G and S1977P only impaired replication as a NS3-5B polyprotein. Furthermore, an S1977P-mutated NS3-5A polyprotein complemented other defects shown to be dependent on NS3-5A for rescue. Overall, our findings suggest the existence of two interdependent sets of protein complexes supporting RNA replication, distinguishable by the minimum polyprotein requirement needed for their formation. IMPORTANCE Positive-strand RNA viruses reshape the intracellular membranes of cells to form a compartment within which to replicate their genome, but little is known about the functional

  20. Formation of three-dimensional hepatic tissue by the bottom-up method using spheroids.

    PubMed

    Okudaira, Tatsuya; Amimoto, Naoki; Mizumoto, Hiroshi; Kajiwara, Toshihisa

    2016-08-01

    Liver regenerative medicine has attracted attention as a possible alternative to organ transplantation. To address the challenge of liver regenerative medicine, the development of a construction method has been proposed for liver tissue in vitro with a high cell density and high functionality for transplantation into patients with severe liver failure. In this study, we fabricated highly functional three-dimensional hepatic tissue by a bottom-up method using spheroids. The hepatic tissue was formed by stacking hepatocyte spheroids covered with human umbilical vein endothelial cells (HUVECs). Hepatic tissue constructs were evaluated for cell survival, liver-specific functions, and histologically. As a result, we identified improvements in liver-specific functions (ammonia removal and albumin secretion) and cell survival. In addition, HUVECs were regularly distributed at every 100 μm within the tissue, and live cells were present within the whole tissue construct throughout the culture period. In summary, we successfully fabricated highly functional hepatic tissue by the bottom-up method using HUVEC-covered hepatocyte spheroids. PMID:26803704

  1. Glycogenic Hepatopathy in Type 1 Diabetes Mellitus.

    PubMed

    Atmaca, Murat; Ucler, Rifki; Kartal, Mehmet; Seven, Ismet; Alay, Murat; Bayram, Irfan; Olmez, Sehmus

    2015-01-01

    Glycogenic hepatopathy is a rare cause of high transaminase levels in type 1 diabetes mellitus. This condition, characterized by elevated liver enzymes and hepatomegaly, is caused by irreversible and excessive accumulation of glycogen in hepatocytes. This is a case report on a 19-year-old male case, diagnosed with glycogenic hepatopathy. After the diagnosis was documented by liver biopsy, the case was put on glycemic control which led to significant decline in hepatomegaly and liver enzymes. It was emphasized that, in type 1 diabetes mellitus cases, hepatopathy should also be considered in the differential diagnoses of elevated liver enzyme and hepatomegaly. PMID:26347835

  2. Glycogenic Hepatopathy in Type 1 Diabetes Mellitus

    PubMed Central

    Atmaca, Murat; Ucler, Rifki; Kartal, Mehmet; Seven, Ismet; Alay, Murat; Bayram, Irfan; Olmez, Sehmus

    2015-01-01

    Glycogenic hepatopathy is a rare cause of high transaminase levels in type 1 diabetes mellitus. This condition, characterized by elevated liver enzymes and hepatomegaly, is caused by irreversible and excessive accumulation of glycogen in hepatocytes. This is a case report on a 19-year-old male case, diagnosed with glycogenic hepatopathy. After the diagnosis was documented by liver biopsy, the case was put on glycemic control which led to significant decline in hepatomegaly and liver enzymes. It was emphasized that, in type 1 diabetes mellitus cases, hepatopathy should also be considered in the differential diagnoses of elevated liver enzyme and hepatomegaly. PMID:26347835

  3. Immunohistochemical localization of glycogen synthase and GSK3β: control of glycogen content in retina.

    PubMed

    Pérezleón, Jorge Alberto; Osorio-Paz, Ixchel; Francois, Liliana; Salceda, Rocío

    2013-05-01

    Glycogen has an important role in energy handling in several brain regions. In the brain, glycogen is localized in astrocytes and its role in several normal and pathological processes has been described, whereas in the retina, glycogen metabolism has been scarcely investigated. The enzyme glycogen phosphorylase has been located in retinal Müller cells; however the cellular location of glycogen synthase (GS) and its regulatory partner, glycogen synthase kinase 3β (GSK3β), has not been investigated. Our aim was to localize these enzymes in the rat retina by immunofluorescence techniques. We found both GS and GSK3β in Müller cells in the synaptic layers, and within the inner segments of photoreceptor cells. The presence of these enzymes in Müller cells suggests that glycogen could be regulated within the retina as in other tissues. Indeed, we showed that glycogen content in the whole retina in vitro was increased by high glucose concentrations, glutamate, and insulin. In contrast, retina glycogen levels were not modified by norepinephrine nor by depolarization with high KCl concentrations. Insulin also induced an increase in glycogen content in cultured Müller cells. The effect of insulin in both, whole retina and cultured Müller cells was blocked by inhibitors of phosphatidyl-inositol 3-kinase, strongly suggesting that glycogen content in retina is modulated by the insulin signaling pathway. The expression of GS and GSK3β in the synaptic layers and photoreceptor cells suggests an important role of GSK3β regulating glycogen synthase in neurons, which opens multiple feasible roles of insulin within the retina. PMID:23512644

  4. No effect of glycogen level on glycogen metabolism during high intensity exercise.

    PubMed

    Vandenberghe, K; Hespel, P; Vanden Eynde, B; Lysens, R; Richter, E A

    1995-09-01

    This study examined the effect of glycogen supercompensation on glycogen breakdown, muscle and blood lactate accumulation, blood-pH, and performance during short-term high-intensity exercise. Young healthy volunteers performed two supramaximal (125% of VO2max) exercise tests on a bicycle ergometer, either for 1 min 45 s (protocol 1; N = 18) or to exhaustion (protocol 2; N = 14). The exercise tests were preceded by either 5 d on a controlled normal (N) diet, or by 2 d of glycogen-depleting exercise accompanied by the normal diet followed by 3 d on a carbohydrate-rich (CHR) diet. In protocol 1, preexercise muscle glycogen concentrations were 364 +/- 23 and 568 +/- 35 mumol.g-1 d.w. in the N and CHR condition, respectively (P < 0.05). During the exertion, glycogen concentration in the M. quadriceps decreased to the same extent in both groups. Accordingly, the exercise-induced increases in muscle and blood-lactate, and the fall in blood-pH were similar during N and CHR. In protocol 2, time to exhaustion was identical for N and CHR. It is concluded that during short-term intense exercise during which muscle glycogen availability exceeds glycogen demand, rate of glycogen breakdown, lactate accumulation, and performance are regulated irrespective of the preexercise muscle glycogen level. PMID:8531626

  5. Hypoxia Promotes Glycogen Accumulation through Hypoxia Inducible Factor (HIF)-Mediated Induction of Glycogen Synthase 1

    PubMed Central

    Pescador, Nuria; Garcia-Rocha, Mar; Ortiz-Barahona, Amaya; Vazquez, Silvia; Ordoñez, Angel; Cuevas, Yolanda; Saez-Morales, David; Garcia-Bermejo, Maria Laura; Landazuri, Manuel O.; Guinovart, Joan; del Peso, Luis

    2010-01-01

    When oxygen becomes limiting, cells reduce mitochondrial respiration and increase ATP production through anaerobic fermentation of glucose. The Hypoxia Inducible Factors (HIFs) play a key role in this metabolic shift by regulating the transcription of key enzymes of glucose metabolism. Here we show that oxygen regulates the expression of the muscle glycogen synthase (GYS1). Hypoxic GYS1 induction requires HIF activity and a Hypoxia Response Element within its promoter. GYS1 gene induction correlated with a significant increase in glycogen synthase activity and glycogen accumulation in cells exposed to hypoxia. Significantly, knockdown of either HIF1α or GYS1 attenuated hypoxia-induced glycogen accumulation, while GYS1 overexpression was sufficient to mimic this effect. Altogether, these results indicate that GYS1 regulation by HIF plays a central role in the hypoxic accumulation of glycogen. Importantly, we found that hypoxia also upregulates the expression of UTP:glucose-1-phosphate urydylyltransferase (UGP2) and 1,4-α glucan branching enzyme (GBE1), two enzymes involved in the biosynthesis of glycogen. Therefore, hypoxia regulates almost all the enzymes involved in glycogen metabolism in a coordinated fashion, leading to its accumulation. Finally, we demonstrated that abrogation of glycogen synthesis, by knock-down of GYS1 expression, impairs hypoxic preconditioning, suggesting a physiological role for the glycogen accumulated during chronic hypoxia. In summary, our results uncover a novel effect of hypoxia on glucose metabolism, further supporting the central importance of metabolic reprogramming in the cellular adaptation to hypoxia. PMID:20300197

  6. Pyruvate dehydrogenase kinase-4 contributes to the recirculation of gluconeogenic precursors during postexercise glycogen recovery

    PubMed Central

    Herbst, Eric A. F.; MacPherson, Rebecca E. K.; LeBlanc, Paul J.; Roy, Brian D.; Jeoung, Nam Ho; Harris, Robert A.

    2013-01-01

    During recovery from glycogen-depleting exercise, there is a shift from carbohydrate oxidation to glycogen resynthesis. The activity of the pyruvate dehydrogenase (PDH) complex may decrease to reduce oxidation of carbohydrates in favor of increasing gluconeogenic recycling of carbohydrate-derived substrates for this process. The precise mechanism behind this has yet to be elucidated; however, research examining mRNA content has suggested that the less-abundant pyruvate dehydrogenase kinase-4 (PDK4) may reduce PDH activation during exercise recovery. To investigate this, skeletal muscle and liver of wild-type (WT) and PDK4-knockout (PDK4-KO) mice were analyzed at rest (Rest), after exercise to exhaustion (Exh), and after 2 h of recovery with ad libitum feeding (Rec). Although there were no differences in exercise tolerance between genotypes, caloric consumption was doubled by PDK4-KO mice during Rec. Because of this, PDK4-KO mice at Rec supercompensated muscle glycogen to 120% of resting stores. Therefore, an extra group of PDK4-KO mice were pair-fed (PF) with WT mice during Rec for comparison. PF mice fully replenished muscle glycogen but recovered only 50% of liver glycogen stores. Concentrations of muscle lactate and alanine were also lower in PF than in WT mice, indicating that this decrease may lead to a potential reduction of recycled gluconeogenic substrates, due to oxidation of their carbohydrate precursors in skeletal muscle, leading to observed reductions in hepatic glucose and glycogen concentrations. Because of the impairments seen in PF PDK4-KO mice, these results suggest a role for PDK4 in regulating the PDH complex in muscle and promoting gluconeogenic precursor recirculation during recovery from exhaustive exercise. PMID:24305065

  7. Xanthohumol ameliorates atherosclerotic plaque formation, hypercholesterolemia, and hepatic steatosis in ApoE-deficient mice

    PubMed Central

    Doddapattar, Prakash; Radović, Branislav; Patankar, Jay V.; Obrowsky, Sascha; Jandl, Katharina; Nusshold, Christoph; Kolb, Dagmar; Vujić, Nemanja; Doshi, Lalit; Chandak, Prakash G.; Goeritzer, Madeleine; Ahammer, Helmut; Hoefler, Gerald; Sattler, Wolfgang; Kratky, Dagmar

    2013-01-01

    Scope Xanthohumol (XN), a prenylated antioxidative and anti-inflammatory chalcone from hops, exhibits positive effects on lipid and glucose metabolism. Based on its favorable biological properties, we investigated whether XN attenuates atherosclerosis in western-type diet-fed apolipoprotein-E-deficient (ApoE−/−) mice. Methods and results XN supplementation markedly reduced plasma cholesterol concentrations, decreased atherosclerotic lesion area, and attenuated plasma concentrations of the proinflammatory cytokine monocyte chemoattractant protein 1. Decreased hepatic triglyceride and cholesterol content, activation of AMP-activated protein kinase, phosphorylation and inactivation of acetyl-CoA carboxylase, and reduced expression levels of mature sterol regulatory element-binding protein (SREBP)-2 and SREBP-1c mRNA indicate reduced lipogenesis in the liver of XN-fed ApoE−/− mice. Concomitant induction of hepatic mRNA expression of carnitine palmitoyltransferase-1a in ApoE−/− mice-administered XN suggests increased fatty acid beta-oxidation. Fecal cholesterol concentrations were also markedly increased in XN-fed ApoE−/− mice compared with mice fed western-type diet alone. Conclusion The atheroprotective effects of XN might be attributed to combined beneficial effects on plasma cholesterol and monocyte chemoattractant protein 1 concentrations and hepatic lipid metabolism via activation of AMP-activated protein kinase. PMID:23650230

  8. Oligosaccharide Binding in Escherichia coli Glycogen Synthase

    SciTech Connect

    Sheng, Fang; Yep, Alejandra; Feng, Lei; Preiss, Jack; Geiger, James H.

    2010-11-17

    Glycogen/starch synthase elongates glucan chains and is the key enzyme in the synthesis of glycogen in bacteria and starch in plants. Cocrystallization of Escherichia coli wild-type glycogen synthase (GS) with substrate ADPGlc and the glucan acceptor mimic HEPPSO produced a closed form of GS and suggests that domain-domain closure accompanies glycogen synthesis. Cocrystallization of the inactive GS mutant E377A with substrate ADPGlc and oligosaccharide results in the first oligosaccharide-bound glycogen synthase structure. Four bound oligosaccharides are observed, one in the interdomain cleft (G6a) and three on the N-terminal domain surface (G6b, G6c, and G6d). Extending from the center of the enzyme to the interdomain cleft opening, G6a mostly interacts with the highly conserved N-terminal domain residues lining the cleft of GS. The surface-bound oligosaccharides G6c and G6d have less interaction with enzyme and exhibit a more curled, helixlike structural arrangement. The observation that oligosaccharides bind only to the N-terminal domain of GS suggests that glycogen in vivo probably binds to only one side of the enzyme to ensure unencumbered interdomain movement, which is required for efficient, continuous glucan-chain synthesis.

  9. Characterization of the highly branched glycogen from the thermoacidophilic red microalga Galdieria sulphuraria and comparison with other glycogens.

    PubMed

    Martinez-Garcia, Marta; Stuart, Marc C A; van der Maarel, Marc J E C

    2016-08-01

    The thermoacidophilic red microalga Galdieria sulphuraria synthesizes glycogen when growing under heterotrophic conditions. Structural characterization revealed that G. sulphuraria glycogen is the most highly branched glycogen described to date, with 18% of α-(1→6) linkages. Moreover, it differs from other glycogens because it is composed of short chains only and has a substantially smaller molecular weight and particle size. The physiological role of this highly branched glycogen in G. sulphuraria is discussed. PMID:27107958

  10. Insights into Brain Glycogen Metabolism: THE STRUCTURE OF HUMAN BRAIN GLYCOGEN PHOSPHORYLASE.

    PubMed

    Mathieu, Cécile; de la Sierra-Gallay, Ines Li; Duval, Romain; Xu, Ximing; Cocaign, Angélique; Léger, Thibaut; Woffendin, Gary; Camadro, Jean-Michel; Etchebest, Catherine; Haouz, Ahmed; Dupret, Jean-Marie; Rodrigues-Lima, Fernando

    2016-08-26

    Brain glycogen metabolism plays a critical role in major brain functions such as learning or memory consolidation. However, alteration of glycogen metabolism and glycogen accumulation in the brain contributes to neurodegeneration as observed in Lafora disease. Glycogen phosphorylase (GP), a key enzyme in glycogen metabolism, catalyzes the rate-limiting step of glycogen mobilization. Moreover, the allosteric regulation of the three GP isozymes (muscle, liver, and brain) by metabolites and phosphorylation, in response to hormonal signaling, fine-tunes glycogenolysis to fulfill energetic and metabolic requirements. Whereas the structures of muscle and liver GPs have been known for decades, the structure of brain GP (bGP) has remained elusive despite its critical role in brain glycogen metabolism. Here, we report the crystal structure of human bGP in complex with PEG 400 (2.5 Å) and in complex with its allosteric activator AMP (3.4 Å). These structures demonstrate that bGP has a closer structural relationship with muscle GP, which is also activated by AMP, contrary to liver GP, which is not. Importantly, despite the structural similarities between human bGP and the two other mammalian isozymes, the bGP structures reveal molecular features unique to the brain isozyme that provide a deeper understanding of the differences in the activation properties of these allosteric enzymes by the allosteric effector AMP. Overall, our study further supports that the distinct structural and regulatory properties of GP isozymes contribute to the different functions of muscle, liver, and brain glycogen. PMID:27402852

  11. FR258900, a potential anti-hyperglycemic drug, binds at the allosteric site of glycogen phosphorylase

    PubMed Central

    Tiraidis, Costas; Alexacou, Kyra-Melinda; Zographos, Spyros E.; Leonidas, Demetres D.; Gimisis, Thanasis; Oikonomakos, Nikos G.

    2007-01-01

    FR258900 has been discovered as a novel inhibitor of human liver glycogen phosphorylase a and proved to suppress hepatic glycogen breakdown and reduce plasma glucose concentrations in diabetic mice models. To elucidate the mechanism of inhibition, we have determined the crystal structure of the cocrystallized rabbit muscle glycogen phosphorylase b–FR258900 complex and refined it to 2.2 Å resolution. The structure demonstrates that the inhibitor binds at the allosteric activator site, where the physiological activator AMP binds. The contacts from FR258900 to glycogen phosphorylase are dominated by nonpolar van der Waals interactions with Gln71, Gln72, Phe196, and Val45′ (from the symmetry-related subunit), and also by ionic interactions from the carboxylate groups to the three arginine residues (Arg242, Arg309, and Arg310) that form the allosteric phosphate-recognition subsite. The binding of FR258900 to the protein promotes conformational changes that stabilize an inactive T-state quaternary conformation of the enzyme. The ligand-binding mode is different from those of the potent phenoxy-phthalate and acyl urea inhibitors, previously described, illustrating the broad specificity of the allosteric site. PMID:17600143

  12. FR258900, a potential anti-hyperglycemic drug, binds at the allosteric site of glycogen phosphorylase.

    PubMed

    Tiraidis, Costas; Alexacou, Kyra-Melinda; Zographos, Spyros E; Leonidas, Demetres D; Gimisis, Thanasis; Oikonomakos, Nikos G

    2007-08-01

    FR258900 has been discovered as a novel inhibitor of human liver glycogen phosphorylase a and proved to suppress hepatic glycogen breakdown and reduce plasma glucose concentrations in diabetic mice models. To elucidate the mechanism of inhibition, we have determined the crystal structure of the cocrystallized rabbit muscle glycogen phosphorylase b-FR258900 complex and refined it to 2.2 A resolution. The structure demonstrates that the inhibitor binds at the allosteric activator site, where the physiological activator AMP binds. The contacts from FR258900 to glycogen phosphorylase are dominated by nonpolar van der Waals interactions with Gln71, Gln72, Phe196, and Val45' (from the symmetry-related subunit), and also by ionic interactions from the carboxylate groups to the three arginine residues (Arg242, Arg309, and Arg310) that form the allosteric phosphate-recognition subsite. The binding of FR258900 to the protein promotes conformational changes that stabilize an inactive T-state quaternary conformation of the enzyme. The ligand-binding mode is different from those of the potent phenoxy-phthalate and acyl urea inhibitors, previously described, illustrating the broad specificity of the allosteric site. PMID:17600143

  13. Cell Fusion Reprogramming Leads to a Specific Hepatic Expression Pattern during Mouse Bone Marrow Derived Hepatocyte Formation In Vivo

    PubMed Central

    Arza, Elvira; Alvarez-Barrientos, Alberto; Fabregat, Isabel; Garcia-Bravo, Maria; Meza, Nestor W.; Segovia, Jose C.

    2012-01-01

    The fusion of bone marrow (BM) hematopoietic cells with hepatocytes to generate BM derived hepatocytes (BMDH) is a natural process, which is enhanced in damaged tissues. However, the reprogramming needed to generate BMDH and the identity of the resultant cells is essentially unknown. In a mouse model of chronic liver damage, here we identify a modification in the chromatin structure of the hematopoietic nucleus during BMDH formation, accompanied by the loss of the key hematopoietic transcription factor PU.1/Sfpi1 (SFFV proviral integration 1) and gain of the key hepatic transcriptional regulator HNF-1A homeobox A (HNF-1A/Hnf1a). Through genome-wide expression analysis of laser captured BMDH, a differential gene expression pattern was detected and the chromatin changes observed were confirmed at the level of chromatin regulator genes. Similarly, Tranforming Growth Factor-β1 (TGF-β1) and neurotransmitter (e.g. Prostaglandin E Receptor 4 [Ptger4]) pathway genes were over-expressed. In summary, in vivo BMDH generation is a process in which the hematopoietic cell nucleus changes its identity and acquires hepatic features. These BMDHs have their own cell identity characterized by an expression pattern different from hematopoietic cells or hepatocytes. The role of these BMDHs in the liver requires further investigation. PMID:22457803

  14. Variation in glycogen concentrations within mantle and foot tissue in Amblema plicata plicata: Implications for tissue biopsy sampling

    USGS Publications Warehouse

    Naimo, T.J.; Monroe, E.M.

    1999-01-01

    With the development of techniques to non-lethally biopsy tissue from unionids, a new method is available to measure changes in biochemical, contaminant, and genetic constituents in this imperiled faunal group. However, before its widespread application, information on the variability of biochemical components within and among tissues needs to be evaluated. We measured glycogen concentrations in foot and mantle tissue in Amblema plicata plicata (Say, 1817) to determine if glycogen was evenly distributed within and between tissues and to determine which tissue might be more responsive to the stress associated with relocating mussels. Glycogen was measured in two groups of mussels: those sampled from their native environment (undisturbed mussels) and quickly frozen for analysis and those relocated into an artificial pond (relocated mussels) for 24 months before analysis. In both undisturbed and relocated mussels, glycogen concentrations were evenly distributed within foot, but not within mantle tissue. In mantle tissue, concentrations of glycogen varied about 2-fold among sections. In addition, glycogen varied significantly between tissues in undisturbed mussels, but not in relocated mussels. Twenty-four months after relocation, glycogen concentrations had declined by 80% in mantle tissue and by 56% in foot tissue relative to the undisturbed mussels. These data indicate that representative biopsy samples can be obtained from foot tissue, but not mantle tissue. We hypothesize that mantle tissue could be more responsive to the stress of relocation due to its high metabolic activity associated with shell formation.

  15. Regulation of glucose and glycogen metabolism during and after exercise.

    PubMed

    Jensen, Thomas E; Richter, Erik A

    2012-03-01

    Utilization of carbohydrate in the form of intramuscular glycogen stores and glucose delivered from plasma becomes an increasingly important energy substrate to the working muscle with increasing exercise intensity. This review gives an update on the molecular signals by which glucose transport is increased in the contracting muscle followed by a discussion of glycogen mobilization and synthesis by the action of glycogen phosphorylase and glycogen synthase, respectively. Finally, this review deals with the signalling relaying the well-described increased sensitivity of glucose transport to insulin in the post-exercise period which can result in an overshoot of intramuscular glycogen resynthesis post exercise (glycogen supercompensation). PMID:22199166

  16. Regulation of glucose and glycogen metabolism during and after exercise

    PubMed Central

    Jensen, Thomas E; Richter, Erik A

    2012-01-01

    Utilization of carbohydrate in the form of intramuscular glycogen stores and glucose delivered from plasma becomes an increasingly important energy substrate to the working muscle with increasing exercise intensity. This review gives an update on the molecular signals by which glucose transport is increased in the contracting muscle followed by a discussion of glycogen mobilization and synthesis by the action of glycogen phosphorylase and glycogen synthase, respectively. Finally, this review deals with the signalling relaying the well-described increased sensitivity of glucose transport to insulin in the post-exercise period which can result in an overshoot of intramuscular glycogen resynthesis post exercise (glycogen supercompensation). PMID:22199166

  17. The VP4 Peptide of Hepatitis A Virus Ruptures Membranes through Formation of Discrete Pores

    PubMed Central

    Shukla, Ashutosh; Padhi, Aditya K.; Gomes, James

    2014-01-01

    ABSTRACT Membrane-active peptides, components of capsid structural proteins, assist viruses in overcoming the host membrane barrier in the initial stages of infection. Several such peptides have been identified, and their roles in membrane fusion or disruption have been characterized through biophysical studies. In several members of the Picornaviridae family, the role of the VP4 structural peptide in cellular-membrane penetration is well established. However, there is not much information on the membrane-penetrating capsid components of hepatitis A virus (HAV), an unusual member of this family. The VP4 peptide of HAV differs from its analogues in other picornaviruses in being significantly shorter in length and in lacking a signal for myristoylation, thought to be a critical requisite for VP4-mediated membrane penetration. Here we report, for the first time, that the atypical VP4 in HAV contains significant membrane-penetrating activity. Using a combination of biophysical assays and molecular dynamics simulation studies, we show that VP4 integrates into membrane vesicles through its N-terminal region to finally form discrete pores of 5- to 9-nm diameter, which induces leakage in the vesicles without altering their overall size or shape. We further demonstrate that the membrane activity of VP4 is specific toward vesicles mimicking the lipid content of late endosomes at acidic pH. Taken together, our data indicate that VP4 might be essential for the penetration of host endosomal membranes and release of the viral genome during HAV entry. IMPORTANCE Hepatitis A virus causes acute hepatitis in humans through the fecal-oral route and is particularly prevalent in underdeveloped regions with poor hygienic conditions. Although a vaccine for HAV exists, its high cost makes it unsuitable for universal application in developing countries. Studies on host-virus interaction for HAV have been hampered due to a lack of starting material, since the virus is extremely slow growing

  18. Pivotal role of glycogen synthase kinase-3: A therapeutic target for Alzheimer's disease.

    PubMed

    Maqbool, Mudasir; Mobashir, Mohammad; Hoda, Nasimul

    2016-01-01

    Neurodegenerative diseases are among the most challenging diseases with poorly known mechanism of cause and paucity of complete cure. Out of all the neurodegenerative diseases, Alzheimer's disease is the most devastating and loosening of thinking and judging ability disease that occurs in the old age people. Many hypotheses came forth in order to explain its causes. In this review, we have enlightened Glycogen Synthase Kinase-3 which has been considered as a concrete cause for Alzheimer's disease. Plaques and Tangles (abnormal structures) are the basic suspects in damaging and killing of nerve cells wherein Glycogen Synthase Kinase-3 has a key role in the formation of these fatal accumulations. Various Glycogen Synthase Kinase-3 inhibitors have been reported to reduce the amount of amyloid-beta as well as the tau hyperphosphorylation in both neuronal and nonneuronal cells. Additionally, Glycogen Synthase Kinase-3 inhibitors have been reported to enhance the adult hippocampal neurogenesis in vivo as well as in vitro. Keeping the chemotype of the reported Glycogen Synthase Kinase-3 inhibitors in consideration, they may be grouped into natural inhibitors, inorganic metal ions, organo-synthetic, and peptide like inhibitors. On the basis of their mode of binding to the constituent enzyme, they may also be grouped as ATP, nonATP, and allosteric binding sites competitive inhibitors. ATP competitive inhibitors were known earlier inhibitors but they lack efficient selectivity. This led to find the new ways for the enzyme inhibition. PMID:26562543

  19. Genetics Home Reference: glycogen storage disease type I

    MedlinePlus

    ... Orphanet: Glycogen storage disease due to glucose-6-phosphatase deficiency Patient Support and Advocacy Resources (7 links) ... JY, Mansfield BC. Mutations in the glucose-6-phosphatase-alpha (G6PC) gene that cause type Ia glycogen ...

  20. Fructose effect to enhance liver glycogen deposition is due to inhibition of glycogenolysis

    SciTech Connect

    Youn, J.; Kaslow, H.; Bergman, R.

    1987-05-01

    The effect of fructose on glycogen degradation was examined by measuring flux of (/sup 14/C) from prelabeled glycogen in perfused rat livers. During 2 h refeeding of fasted rats hepatic glycogen was labeled by injection of (U /sup 14/C) galactose (0.1 mg and 0.02 ..mu..Ci/g of body weight). Refed livers were perfused for 30 min with glucose only (10 mM) and for 60 min with glucose (10 mM) without (n=5) or with fructose (1, 2, 10 mM; n=5 for each). With fructose, label production immediately declined and remained suppressed through the end of perfusion (P < 0.05). Suppression was dose-dependent: steady state label production was suppressed 45, 64, and 72% by 1, 2, and 10 mM fructose (P < 0.0001), without significant changes in glycogen synthase or phosphorylase. These results suggest the existence of allosteric inhibition of phosphorylase in the presence of fructose. Fructose 1-phosphate (F1P) accumulated in proportion to fructose (0.11 +/- 0.01 without fructose, 0.86 +/- 0.03, 1.81 +/- 0.18, and 8.23 +/- 0.6 ..mu..moles/g of liver with 1, 2, and 10 mM fructose. Maximum inhibition of phosphorylase was 82%; FIP concentration for half inhibition was 0.57 ..mu..moles/g of liver, well within the concentration of F1P attained in refeeding. Fructose enhances net glycogen synthesis in liver by suppressing glycogenolysis and the suppression is presumably caused by allosteric inhibition of phosphorylase by F1P.

  1. Glycogen metabolism in the liver of the neonatal gsd/gsd and control (GSD/GSD) rat.

    PubMed Central

    Clark, D G; Neville, S D; Brinkman, M; Filsell, O H

    1982-01-01

    1. The metabolism of hepatic glycogen, labelled with [6-3H]glucose at day 19.5 of gestation and with 14C from [U-14C]galactose at delivery, was followed for 10 h in food-deprived gsd/gsd and control (GSD/GSD) neonatal rats. 2. In the affected pups glycogen was maintained at 12% (w/w) and there was no loss of incorporated radioactivity. 3. The 3H and 14C in glycogen from the controls were both decreased by 80%, but 14C was removed at 0--5 h and [6-3H]glucose at 5--10 h. 4. Blood glucose concentrations in the unaffected neonatal rats fell from 5.3 mM at 20 min to 1.7 mM after 10 h. In the gsd/gsd pups blood glucose concentration was decreased from 2 mM at birth to 0.3 mM at 2.5 h: it was maintained at 0.8 mM between 5 and 10 h. 5. In neonatal rats that had been dead for 10 h, hepatic glycogen was decreased by 34% in the controls and by 22% in the gsd/gsd pups. These results demonstrate that liver from the affected rats contains glycogenolytic activity, but that it is not expressed in living tissue. PMID:6953968

  2. Genetics Home Reference: glycogen storage disease type VI

    MedlinePlus

    ... a result, liver cells cannot use glycogen for energy. Since glycogen cannot be broken down, it accumulates within liver cells, causing these cells to become enlarged and dysfunctional. Learn more about the gene associated with glycogen storage disease type VI PYGL Related Information What is ...

  3. Effect of diabetes on glycogen metabolism in rat retina.

    PubMed

    Sánchez-Chávez, Gustavo; Hernández-Berrones, Jethro; Luna-Ulloa, Luis Bernardo; Coffe, Víctor; Salceda, Rocío

    2008-07-01

    Glucose is the main fuel for energy metabolism in retina. The regulatory mechanisms that maintain glucose homeostasis in retina could include hormonal action. Retinopathy is one of the chemical manifestations of long-standing diabetes mellitus. In order to better understand the effect of hyperglycemia in retina, we studied glycogen content as well as glycogen synthase and phosphorylase activities in both normal and streptozotocin-induced diabetic rat retina and compared them with other tissues. Glycogen levels in normal rat retina are low (46 +/- 4.0 nmol glucosyl residues/mg protein). However, high specific activity of glycogen synthase was found in retina, indicating a substantial capacity for glycogen synthesis. In diabetic rats, glycogen synthase activity increased between 50% and 100% in retina, brain cortex and liver of diabetic rats, but only retina exhibited an increase in glycogen content. Although, total and phosphorylated glycogen synthase levels were similar in normal and diabetic retina, activation of glycogen synthase by glucose-6-P was remarkable increased. Glycogen phosphorylase activity decreased 50% in the liver of diabetic animals; it was not modified in the other tissues examined. We conclude that the increase in glycogen levels in diabetic retina was due to alterations in glycogen synthase regulation. PMID:18274898

  4. Genetics Home Reference: glycogen storage disease type IX

    MedlinePlus

    ... cellular energy is a simple sugar called glucose. Glucose is stored in muscle and liver cells in a form called glycogen. Glycogen can ... result, glycogen accumulates in and damages cells, and glucose is not available for ... in the liver leads to hepatomegaly, and the liver's inability to ...

  5. Glycogen contains phosphodiester groups that can be introduced by UDPglucose: glycogen glucose 1-phosphotransferase.

    PubMed

    Lomako, J; Lomako, W M; Whelan, W J; Marchase, R B

    1993-08-30

    Rabbit-muscle glycogen contains covalently bound phosphorus, equivalent to 1 phosphate group per 208 glucose residues. This often disputed, minor component was previously thought to represent a phosphomonoester group at C-6 of a glucose residue. Here we show that more than half the phosphorus is present as a phosphodiester, the remainder being monoester. A novel enzyme activity has been found in muscle that can account for the presence of the phosphodiester in glycogen. This is a UDPglucose: glycogen glucose 1-phosphotransferase that positions glucose 1-phosphate on C-6 of glucose residues in glycogen, forming a diester. The phosphomonoester groups present may arise by removal of the glucose residue originally transferred as glucose 1-phosphate. PMID:8396041

  6. Molecular Structure of Human-Liver Glycogen

    PubMed Central

    Deng, Bin; Sullivan, Mitchell A.; Chen, Cheng; Li, Jialun; Powell, Prudence O.; Hu, Zhenxia; Gilbert, Robert G.

    2016-01-01

    Glycogen is a highly branched glucose polymer which is involved in maintaining blood-sugar homeostasis. Liver glycogen contains large composite α particles made up of linked β particles. Previous studies have shown that the binding which links β particles into α particles is impaired in diabetic mice. The present study reports the first molecular structural characterization of human-liver glycogen from non-diabetic patients, using transmission electron microscopy for morphology and size-exclusion chromatography for the molecular size distribution; the latter is also studied as a function of time during acid hydrolysis in vitro, which is sensitive to certain structural features, particularly glycosidic vs. proteinaceous linkages. The results are compared with those seen in mice and pigs. The molecular structural change during acid hydrolysis is similar in each case, and indicates that the linkage of β into α particles is not glycosidic. This result, and the similar morphology in each case, together imply that human liver glycogen has similar molecular structure to those of mice and pigs. This knowledge will be useful for future diabetes drug targets. PMID:26934359

  7. Gender-related differences in the formation of skatole metabolites by specific CYP450 in porcine hepatic S9 fractions.

    PubMed

    Borrisser-Pairó, F; Rasmussen, M K; Ekstrand, B; Zamaratskaia, G

    2015-04-01

    Higher accumulation of skatole in the fat of male pigs compared with female pigs might be due to gender-related differences in the rate of skatole degradation. In the present study, skatole metabolites and cytochrome P450 (CYP450) isoforms involved in skatole metabolism were for the first time investigated in hepatic S9 fractions from six male and four female pigs (crossbred Landrace×Yorkshire dams and Duroc boar). Surprisingly, the rates of production of major skatole metabolites were similar in male and female pigs. The most abundant metabolite of skatole was 3-hydroxy-3-methyloxindole (HMOI) followed by 3-methyloxindole and indole-3-carbinol in both male and female S9 fractions. Concentrations of formed HMOI and 3-methyloxindole did not differ between the genders (P=0.124 for HMOI, and P=0.575 for 3-methyloxindole). Indole-3-carbinol formation was higher in S9 fractions from the females compared with male pigs (P=0.0001). Enzyme kinetic parameters were similar for both genders (P>0.05). In both male and female pigs, ellipticine, diallyl sulphide (DAS) and quercetin inhibited HMOI formation, confirming the involvement of CYP1A1 and CYP2E1. The formation of 3-methyloxindole was reduced in the presence of the CYP2E1 inhibitor DAS, and formation of indole-3-carbinol was reduced in the presence of CYP1A1 and CYP2A19 inhibitors. We found only minor differences in skatole metabolism between male and female pigs, particularly the involvement of CYP2C and CYP3A in indole-3-carbinol formation in female but not in male pigs. This is a very essential finding, suggesting the involvement of larger number of CYP450 isoforms in female pigs. On the other hand, indole-3-carbinol is a minor skatole metabolite, and the physiological significance of CYP2C and CYP3A involvement in its formation in female pigs, but not in male pigs, needs to be elucidated. Our results, however, should be interpreted with caution because of the low number of animals and possibility of breed and age

  8. Glycogen with short average chain length enhances bacterial durability

    NASA Astrophysics Data System (ADS)

    Wang, Liang; Wise, Michael J.

    2011-09-01

    Glycogen is conventionally viewed as an energy reserve that can be rapidly mobilized for ATP production in higher organisms. However, several studies have noted that glycogen with short average chain length in some bacteria is degraded very slowly. In addition, slow utilization of glycogen is correlated with bacterial viability, that is, the slower the glycogen breakdown rate, the longer the bacterial survival time in the external environment under starvation conditions. We call that a durable energy storage mechanism (DESM). In this review, evidence from microbiology, biochemistry, and molecular biology will be assembled to support the hypothesis of glycogen as a durable energy storage compound. One method for testing the DESM hypothesis is proposed.

  9. Radiometric assays for glycerol, glucose, and glycogen

    SciTech Connect

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

    1989-07-01

    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.

  10. Radiometric assays for glycerol, glucose, and glycogen.

    PubMed

    Bradley, D C; Kaslow, H R

    1989-07-01

    We have developed radiometric assays for small quantities of glycerol, glucose and glycogen, based on a technique described by Thorner and Paulus (1971, J. Biol. Chem. 246, 3885-3894) 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. PMID:2817333

  11. Keratin 8/18 regulation of glucose metabolism in normal versus cancerous hepatic cells through differential modulation of hexokinase status and insulin signaling

    SciTech Connect

    Mathew, Jasmin; Loranger, Anne; Gilbert, Stéphane; Faure, Robert; Marceau, Normand

    2013-02-15

    As differentiated cells, hepatocytes primarily metabolize glucose for ATP production through oxidative phosphorylation of glycolytic pyruvate, whereas proliferative hepatocellular carcinoma (HCC) cells undergo a metabolic shift to aerobic glycolysis despite oxygen availability. Keratins, the intermediate filament (IF) proteins of epithelial cells, are expressed as pairs in a lineage/differentiation manner. Hepatocyte and HCC (hepatoma) cell IFs are made solely of keratins 8/18 (K8/K18), thus providing models of choice to address K8/K18 IF functions in normal and cancerous epithelial cells. Here, we demonstrate distinctive increases in glucose uptake, glucose-6-phosphate formation, lactate release, and glycogen formation in K8/K18 IF-lacking hepatocytes and/or hepatoma cells versus their respective IF-containing counterparts. We also show that the K8/K18-dependent glucose uptake/G6P formation is linked to alterations in hexokinase I/II/IV content and localization at mitochondria, with little effect on GLUT1 status. In addition, we find that the insulin-stimulated glycogen formation in normal hepatocytes involves the main PI-3 kinase-dependent signaling pathway and that the K8/K18 IF loss makes them more efficient glycogen producers. In comparison, the higher insulin-dependent glycogen formation in K8/K18 IF-lacking hepatoma cells is associated with a signaling occurring through a mTOR-dependent pathway, along with an augmentation in cell proliferative activity. Together, the results uncover a key K8/K18 regulation of glucose metabolism in normal and cancerous hepatic cells through differential modulations of mitochondrial HK status and insulin-mediated signaling.

  12. Hepatitis Risk Assessment

    MedlinePlus

    ... About the Division of Viral Hepatitis Contact Us File Formats Help: How do I view different file formats (PDF, DOC, PPT, MPEG) on this site? Adobe PDF file Microsoft PowerPoint file Microsoft Word file Microsoft Excel ...

  13. Glycogen and its metabolism: some new developments and old themes

    PubMed Central

    Roach, Peter J.; Depaoli-Roach, Anna A.; Hurley, Thomas D.; Tagliabracci, Vincent S.

    2016-01-01

    Glycogen is a branched polymer of glucose that acts as a store of energy in times of nutritional sufficiency for utilization in times of need. Its metabolism has been the subject of extensive investigation and much is known about its regulation by hormones such as insulin, glucagon and adrenaline (epinephrine). There has been debate over the relative importance of allosteric compared with covalent control of the key biosynthetic enzyme, glycogen synthase, as well as the relative importance of glucose entry into cells compared with glycogen synthase regulation in determining glycogen accumulation. Significant new developments in eukaryotic glycogen metabolism over the last decade or so include: (i) three-dimensional structures of the biosynthetic enzymes glycogenin and glycogen synthase, with associated implications for mechanism and control; (ii) analyses of several genetically engineered mice with altered glycogen metabolism that shed light on the mechanism of control; (iii) greater appreciation of the spatial aspects of glycogen metabolism, including more focus on the lysosomal degradation of glycogen; and (iv) glycogen phosphorylation and advances in the study of Lafora disease, which is emerging as a glycogen storage disease. PMID:22248338

  14. Reaction Kinetics of Substrate Transglycosylation Catalyzed by TreX of Sulfolobus solfataricus and Effects on Glycogen Breakdown

    PubMed Central

    Nguyen, Dang Hai Dang; Park, Jong-Tae; Shim, Jae-Hoon; Tran, Phuong Lan; Oktavina, Ershita Fitria; Nguyen, Thi Lan Huong; Lee, Sung-Jae; Park, Cheon-Seok; Li, Dan; Park, Sung-Hoon; Stapleton, David; Lee, Jin-Sil

    2014-01-01

    We studied the activity of a debranching enzyme (TreX) from Sulfolobus solfataricus on glycogen-mimic substrates, branched maltotetraosyl-β-cyclodextrin (Glc4-β-CD), and natural glycogen to better understand substrate transglycosylation and the effect thereof on glycogen debranching in microorganisms. The validation test of Glc4-β-CD as a glycogen mimic substrate showed that it followed the breakdown process of the well-known yeast and rat liver extract. TreX catalyzed both hydrolysis of α-1,6-glycosidic linkages and transglycosylation at relatively high (>0.5 mM) substrate concentrations. TreX transferred maltotetraosyl moieties from the donor substrate to acceptor molecules, resulting in the formation of two positional isomers of dimaltotetraosyl-α-1,6-β-cyclodextrin [(Glc4)2-β-CD]; these were 61,63- and 61,64-dimaltotetraosyl-α-1,6-β-CD. Use of a modified Michaelis-Menten equation to study substrate transglycosylation revealed that the kcat and Km values for transglycosylation were 1.78 × 103 s−1 and 3.30 mM, respectively, whereas the values for hydrolysis were 2.57 × 103 s−1 and 0.206 mM, respectively. Also, enzyme catalytic efficiency (the kcat/Km ratio) increased as the degree of polymerization of branch chains rose. In the model reaction system of Escherichia coli, glucose-1-phosphate production from glycogen by the glycogen phosphorylase was elevated ∼1.45-fold in the presence of TreX compared to that produced in the absence of TreX. The results suggest that outward shifting of glycogen branch chains via transglycosylation increases the number of exposed chains susceptible to phosphorylase action. We developed a model of the glycogen breakdown process featuring both hydrolysis and transglycosylation catalyzed by the debranching enzyme. PMID:24610710

  15. Glycogen metabolism in rat heart muscle cultures after hypoxia.

    PubMed

    Vigoda, Ayelet; Mamedova, Liaman K; Shneyvays, Vladimir; Katz, Abram; Shainberg, Asher

    2003-12-01

    Elevated glycogen levels in heart have been shown to have cardioprotective effects against ischemic injury. We have therefore established a model for elevating glycogen content in primary rat cardiac cells grown in culture and examined potential mechanisms for the elevation (glycogen supercompensation). Glycogen was depleted by exposing the cells to hypoxia for 2 h in the absence of glucose in the medium. This was followed by incubating the cells with 28 mM glucose in normoxia for up to 120 h. Hypoxia decreased glycogen content to about 15% of control, oxygenated cells. This was followed by a continuous increase in glycogen in the hypoxia treated cells during the 120 h recovery period in normoxia. By 48 h after termination of hypoxia, the glycogen content had returned to baseline levels and by 120 h glycogen was about 150% of control. The increase in glycogen at 120 h was associated with comparable relative increases in glucose uptake (approximately 180% of control) and the protein level of the glut-1 transporter (approximately 170% of control), whereas the protein level of the glut-4 transporter was decreased to < 10% of control. By 120 h, the hypoxia-treated cells also exhibited marked increases in the total (approximately 170% of control) and fractional activity of glycogen synthase (control, approximately 15%; hypoxia-treated, approximately 30%). Concomitantly, the hypoxia-treated cells also exhibited marked decreases in the total (approximately 50% of control) and fractional activity of glycogen phosphorylase (control, approximately 50%; hypoxia-treated, approximately 25%). Thus, we have established a model of glycogen supercompensation in cultures of cardiac cells that is explained by concerted increases in glucose uptake and glycogen synthase activity and decreases in phosphorylase activity. This model should prove useful in studying the cardioprotective effects of glycogen. PMID:14674711

  16. Identification of Disubstituted Sulfonamide Compounds as Specific Inhibitors of Hepatitis B Virus Covalently Closed Circular DNA Formation

    PubMed Central

    Cai, Dawei; Mills, Courtney; Yu, Wenquan; Yan, Ran; Aldrich, Carol E.; Saputelli, Jeffry R.; Mason, William S.; Xu, Xiaodong; Guo, Ju-Tao; Block, Timothy M.

    2012-01-01

    Hepatitis B virus (HBV) covalently closed circular DNA (cccDNA) plays a central role in viral infection and persistence and is the basis for viral rebound after the cessation of therapy, as well as the elusiveness of a cure even after extended treatment. Therefore, there is an urgent need for the development of novel therapeutic agents that directly target cccDNA formation and maintenance. By employing an innovative cell-based cccDNA assay in which secreted HBV e antigen is a cccDNA-dependent surrogate, we screened an in-house small-molecule library consisting of 85,000 drug-like compounds. Two structurally related disubstituted sulfonamides (DSS), termed CCC-0975 and CCC-0346, emerged and were confirmed as inhibitors of cccDNA production, with low micromolar 50% effective concentrations (EC50s) in cell culture. Further mechanistic studies demonstrated that DSS compound treatment neither directly inhibited HBV DNA replication in cell culture nor reduced viral polymerase activity in the in vitro endogenous polymerase assay but synchronously reduced the levels of HBV cccDNA and its putative precursor, deproteinized relaxed circular DNA (DP-rcDNA). However, DSS compounds did not promote the intracellular decay of HBV DP-rcDNA and cccDNA, suggesting that the compounds interfere primarily with rcDNA conversion into cccDNA. In addition, we demonstrated that CCC-0975 was able to reduce cccDNA biosynthesis in duck HBV-infected primary duck hepatocytes. This is the first attempt, to our knowledge, to identify small molecules that target cccDNA formation, and DSS compounds thus potentially serve as proof-of-concept drug candidates for development into therapeutics to eliminate cccDNA from chronic HBV infection. PMID:22644022

  17. Glutamate Cysteine Ligase—Modulatory Subunit Knockout Mouse Shows Normal Insulin Sensitivity but Reduced Liver Glycogen Storage

    PubMed Central

    Lavoie, Suzie; Steullet, Pascal; Kulak, Anita; Preitner, Frederic; Do, Kim Q.; Magistretti, Pierre J.

    2016-01-01

    Glutathione (GSH) deficits have been observed in several mental or degenerative illness, and so has the metabolic syndrome. The impact of a decreased glucose metabolism on the GSH system is well-known, but the effect of decreased GSH levels on the energy metabolism is unclear. The aim of the present study was to investigate the sensitivity to insulin in the mouse knockout (KO) for the modulatory subunit of the glutamate cysteine ligase (GCLM), the rate-limiting enzyme of GSH synthesis. Compared to wildtype (WT) mice, GCLM-KO mice presented with reduced basal plasma glucose and insulin levels. During an insulin tolerance test, GCLM-KO mice showed a normal fall in glycemia, indicating normal insulin secretion. However, during the recovery phase, plasma glucose levels remained lower for longer in KO mice despite normal plasma glucagon levels. This is consistent with a normal counterregulatory hormonal response but impaired mobilization of glucose from endogenous stores. Following a resident-intruder stress, during which stress hormones mobilize glucose from hepatic glycogen stores, KO mice showed a lower hyperglycemic level despite higher plasma cortisol levels when compared to WT mice. The lower hepatic glycogen levels observed in GCLM-KO mice could explain the impaired glycogen mobilization following induced hypoglycemia. Altogether, our results indicate that reduced liver glycogen availability, as observed in GCLM-KO mice, could be at the origin of their lower basal and challenged glycemia. Further studies will be necessary to understand how a GSH deficit, typically observed in GCLM-KO mice, leads to a deficit in liver glycogen storage. PMID:27148080

  18. Non-invasive quantification of brain glycogen absolute concentration

    PubMed Central

    van Heeswijk, Ruud B.; Xin, Lijing; Laus, Sabrina; Frenkel, Hanne; Lei, Hongxia; Gruetter, Rolf

    2009-01-01

    The only currently available method to measure brain glycogen in vivo is 13C NMR spectroscopy. Incorporation of 13C-labeled glucose (Glc) is necessary to allow glycogen measurement, but might be affected by turnover changes. Our aim was to measure glycogen absolute concentration in the rat brain by eliminating label turnover as variable. The approach is based on establishing an increased, constant 13C isotopic enrichment (IE). 13C-Glc infusion is then performed at the IE of brain glycogen. As glycogen IE cannot be assessed in vivo, we validated that it can be inferred from that of N-acetyl-aspartate IE in vivo: After [1-13C]-Glc ingestion, glycogen IE was 2.2 ± 0.1 fold that of N-acetyl-aspartate (n = 11, R2 = 0.77). After subsequent Glc infusion, glycogen IE equaled brain Glc IE (n = 6, paired t-test, p = 0.37), implying isotopic steady-state achievement and complete turnover of the glycogen molecule. Glycogen concentration measured in vivo by 13C NMR (mean ± SD: 5.8 ± 0.7 μmol/g) was in excellent agreement with that in vitro (6.4 ± 0.6 μmol/g, n = 5). When insulin was administered, the stability of glycogen concentration was analogous to previous biochemical measurements implying that glycogen turnover is activated by insulin. We conclude that the entire glycogen molecule is turned over and that insulin activates glycogen turnover. PMID:19013831

  19. Dietary whey protein hydrolysates increase skeletal muscle glycogen levels via activation of glycogen synthase in mice.

    PubMed

    Kanda, Atsushi; Morifuji, Masashi; Fukasawa, Tomoyuki; Koga, Jinichiro; Kanegae, Minoru; Kawanaka, Kentaro; Higuchi, Mitsuru

    2012-11-14

    Previously, we have shown that consuming carbohydrate plus whey protein hydrolysates (WPHs) replenished muscle glycogen after exercise more effectively than consuming intact whey protein or branched-chain amino acids (BCAAs). The mechanism leading to superior glycogen replenishment after consuming WPH is unclear. In this 5 week intervention, ddY mice were fed experimental diets containing WPH, a mixture of whey amino acids (WAAs), or casein (control). After the intervention, gastrocnemius muscle glycogen levels were significantly higher in the WPH group (4.35 mg/g) than in the WAA (3.15 mg/g) or control (2.51 mg/g) groups. In addition, total glycogen synthase (GS) protein levels were significantly higher in the WPH group (153%) than in the WAA (89.2%) or control groups, and phosphorylated GS levels were significantly decreased in the WPH group (51.4%). These results indicate that dietary WPH may increase the muscle glycogen content through increased GS activity. PMID:23113736

  20. MicroRNA 152 regulates hepatic glycogenesis by targeting PTEN.

    PubMed

    Wang, Shuyue; Wang, Lilin; Dou, Lin; Guo, Jun; Fang, Weiwei; Li, Meng; Meng, Xiangyu; Man, Yong; Shen, Tao; Huang, Xiuqing; Li, Jian

    2016-05-01

    Hepatic insulin resistance, defined as a diminished ability of hepatocytes to respond to the action of insulin, plays an important role in the development of type 2 diabetes and metabolic syndrome. Aberrant expression of mmu-miR-152-3p (miR-152) is related to the pathogenesis of tumors such as hepatitis B virus related hepatocellular carcinoma. However, the role of miR-152 in hepatic insulin resistance remains unknown. In the present study, we identified the potential role of miR-152 in regulating hepatic glycogenesis. The expression of miR-152 and the level of glycogen were significantly downregulated in the liver of db/db mice and mice fed a high fat diet. In vivo and in vitro results suggest that inhibition of miR-152 expression induced impaired glycogenesis in hepatocytes. Interestingly, miR-152 expression, glycogen synthesis and protein kinase B/glycogen synthase kinase (AKT/GSK) pathway activation were significantly decreased in the liver of mice injected with 16 μg·mL(-1) interleukin 6 (IL-6) by pumps for 7 days and in NCTC 1469 cells treated with 10 ng·mL(-1) IL-6 for 24 h. Moreover, hepatic overexpression of miR-152 rescued IL-6-induced impaired glycogenesis. Finally, phosphatase and tensin homolog (PTEN) was identified as a direct target of miR-152 to mediate hepatic glycogen synthesis. Our findings provide mechanistic insight into the effects of miR-152 on the regulation of the AKT/GSK pathway and the synthesis of glycogen in hepatocytes. Downregulated miR-152 induced impaired hepatic glycogenesis by targeting PTEN. PTEN participated in miR-152-mediated glycogenesis in hepatocytes via regulation of the AKT/GSK pathway. PMID:26996529

  1. Controlled formation of heterotypic hepatic micro-organoids in anisotropic hydrogel microfibers for long-term preservation of liver-specific functions.

    PubMed

    Yamada, Masumi; Utoh, Rie; Ohashi, Kazuo; Tatsumi, Kohei; Yamato, Masayuki; Okano, Teruo; Seki, Minoru

    2012-11-01

    We have developed a hydrogel-based cell cultivation platform for forming 3D restiform hepatic micro-organoids consisting of primary rat hepatocytes and feeder cells (Swiss 3T3 cells). Sodium alginate solutions containing hepatocytes/3T3 cells were continuously introduced into a microfluidic channel to produce cell-incorporating anisotropic Ba-alginate hydrogel microfibers, where hepatocytes at the center were closely sandwiched by 3T3 cells. Hydrogel fiber-based cultivation under high oxygen tension enabled the formation of heterotypic micro-organoids with a length of up to 1 mm and a diameter of ∼50 μm, mimicking the hepatic cord structures found in the liver, while maintaining a high hepatocyte viability (∼80%) over 30 days. Long-term observation of up to 90 days revealed a significant enhancement of hepatic functions because of heterotypic and homotypic cell-cell interactions, including albumin secretion and urea synthesis as well as expression of hepatocyte-specific genes, compared with conventional monolayer culture and single cultivation in the hydrogel fibers. The encapsulated hepatic constructs were recovered as scaffold-free micro-organoids by enzymatically digesting the hydrogel matrices using alginate lyase. This technique for creating heterotypic micro-organoids with precisely ordered multiple cell types will be useful for the development of a new liver tissue engineering approach and may be applicable to the fabrication of extracorporeal bioartificial liver (BAL) devices and assessment tools for drug development and testing. PMID:22906609

  2. Monogenic control of variations in antipyrine metabolite formation. New polymorphism of hepatic drug oxidation.

    PubMed Central

    Penno, M B; Vesell, E S

    1983-01-01

    To investigate mechanisms that control large variations among normal uninduced subjects in the elimination of the model compound antipyrine (AP) and other drugs, AP was administered to 144 subjects (83 unrelated adults and 61 members of 13 families). Thereafter, at regular intervals for 72 h, the urine of each subject was collected and concentrations of AP and its three main metabolites measured. From these urinary concentrations, rate constants for formation of each AP metabolite were calculated. Trimodal curves were observed when values for each AP rate constant were plotted in 83 unrelated subjects; probit plots of these values showed inflections at the two antimodes of each trimodal distribution. All members of our 13 families were assigned one of three phenotypes determined by where their AP metabolite rate constant placed them in the trimodal distributions derived from the 83 unrelated subjects. In each family, pedigree analysis to identify the mode of transmission of these three phenotypes was consistent with their monogenic control. These results provide evidence for a new polymorphism of drug oxidation in man. PMID:6863539

  3. Effects of commonly used cryoprotectants on glycogen phosphorylase activity and structure.

    PubMed

    Tsitsanou, K E; Oikonomakos, N G; Zographos, S E; Skamnaki, V T; Gregoriou, M; Watson, K A; Johnson, L N; Fleet, G W

    1999-04-01

    The effects of a number of cryoprotectants on the kinetic and structural properties of glycogen phosphorylase b have been investigated. Kinetic studies showed that glycerol, one of the most commonly used cryoprotectants in X-ray crystallographic studies, is a competitive inhibitor with respect to substrate glucose-1-P with an apparent Ki value of 3.8% (v/v). Cryogenic experiments, with the enzyme, have shown that glycerol binds at the catalytic site and competes with glucose analogues that bind at the catalytic site, thus preventing the formation of complexes. This necessitated a change in the conditions for cryoprotection in crystallographic binding experiments with glycogen phosphorylase. It was found that 2-methyl-2,4-pentanediol (MPD), polyethylene glycols (PEGs) of various molecular weights, and dimethyl sulfoxide (DMSO) activated glycogen phosphorylase b to different extents, by stabilizing its most active conformation, while sucrose acted as a noncompetitive inhibitor and ethylene glycol as an uncompetitive inhibitor with respect to glucose-1-P. A parallel experimental investigation by X-ray crystallography showed that, at 100 K, both MPD and DMSO do not bind at the catalytic site, do not induce any significant conformational change on the enzyme molecule, and hence, are more suitable cryoprotectants than glycerol for binding studies with glycogen phosphorylase. PMID:10211820

  4. Effects of commonly used cryoprotectants on glycogen phosphorylase activity and structure.

    PubMed Central

    Tsitsanou, K. E.; Oikonomakos, N. G.; Zographos, S. E.; Skamnaki, V. T.; Gregoriou, M.; Watson, K. A.; Johnson, L. N.; Fleet, G. W.

    1999-01-01

    The effects of a number of cryoprotectants on the kinetic and structural properties of glycogen phosphorylase b have been investigated. Kinetic studies showed that glycerol, one of the most commonly used cryoprotectants in X-ray crystallographic studies, is a competitive inhibitor with respect to substrate glucose-1-P with an apparent Ki value of 3.8% (v/v). Cryogenic experiments, with the enzyme, have shown that glycerol binds at the catalytic site and competes with glucose analogues that bind at the catalytic site, thus preventing the formation of complexes. This necessitated a change in the conditions for cryoprotection in crystallographic binding experiments with glycogen phosphorylase. It was found that 2-methyl-2,4-pentanediol (MPD), polyethylene glycols (PEGs) of various molecular weights, and dimethyl sulfoxide (DMSO) activated glycogen phosphorylase b to different extents, by stabilizing its most active conformation, while sucrose acted as a noncompetitive inhibitor and ethylene glycol as an uncompetitive inhibitor with respect to glucose-1-P. A parallel experimental investigation by X-ray crystallography showed that, at 100 K, both MPD and DMSO do not bind at the catalytic site, do not induce any significant conformational change on the enzyme molecule, and hence, are more suitable cryoprotectants than glycerol for binding studies with glycogen phosphorylase. PMID:10211820

  5. Viral Hepatitis

    MedlinePlus

    ... Public Home » For Veterans and the Public Viral Hepatitis Menu Menu Viral Hepatitis Viral Hepatitis Home For ... the Public Veterans and Public Home How is Hepatitis C Treated? Find the facts about the newest ...

  6. PP2A inhibition results in hepatic insulin resistance despite Akt2 activation.

    PubMed

    Galbo, Thomas; Perry, Rachel J; Nishimura, Erica; Samuel, Varman T; Quistorff, Bjørn; Shulman, Gerald I

    2013-10-01

    In the liver, insulin suppresses hepatic gluconeogenesis by activating Akt, which inactivates the key gluconeogenic transcription factor FoxO1 (Forkhead Box O1). Recent studies have implicated hyperactivity of the Akt phosphatase Protein Phosphatase 2A (PP2A) and impaired Akt signaling as a molecular defect underlying insulin resistance. We therefore hypothesized that PP2A inhibition would enhance insulin-stimulated Akt activity and decrease glucose production. PP2A inhibitors increased hepatic Akt phosphorylation and inhibited FoxO1in vitro and in vivo, and suppressed gluconeogenesis in hepatocytes. Paradoxically, PP2A inhibition exacerbated insulin resistance in vivo. This was explained by phosphorylation of both hepatic glycogen synthase (GS) (inactivation) and phosphorylase (activation) resulting in impairment of glycogen storage. Our findings underline the significance of GS and Phosphorylase as hepatic PP2A substrates and importance of glycogen metabolism in acute plasma glucose regulation. PMID:24150286

  7. Attenuation of Helicteres isora L. bark extracts on streptozotocin-induced alterations in glycogen and carbohydrate metabolism in albino rats.

    PubMed

    Kumar, G; Sharmila Banu, G; Murugesan, A G

    2009-11-01

    The present study was undertaken to assess the effect of Helicteres isora L. on four important enzymes of carbohydrate metabolism (glucokinase [GK], hexokinase [HK] phosphofructokinase [PFK] and fructose-1, 6-bisphosphatase [FBP]) along with glycogen content of insulin-dependent (skeletal muscle and liver) and insulin-independent tissues (kidneys and brain) in streptozotocin (STZ; 60 mg/kg)-induced model of diabetes for 30 days. Administration of bark extracts (100, 200 mg/kg) for 30 days led to decrease in plasma glucose levels by approximately 9.60% and 22.04% and 19.18% and 33.93% on 15th and 30th day, respectively, of the experiment. Liver and two-kidney weight expressed as percentage of body weight significantly increased in diabetics (P < 0.05) versus normal controls. Renal glycogen content increased by 10 folds while hepatic and skeletal muscle glycogen content decreased by 75% and 68% in diabetic controls versus controls. H. isora did not affect glycogen content in any tissue. The decreased activities of PFK, GK, FBP and HK in diabetic controls were 40%, 50%, 50% and 60% and bark extract of H. isora partially corrected this alteration. The efficacy of the bark extract was comparable with Tolbutamide, a well-known hypoglycemic drug. PMID:19812119

  8. Three consecutive pregnancies in a patient with glycogen storage disease type IA (von Gierke's disease).

    PubMed

    Ryan, I P; Havel, R J; Laros, R K

    1994-06-01

    Glycogen storage disease type IA is associated with metabolic abnormalities that can compromise fetal outcome. Normal outcome can be achieved by maintaining euglycemia throughout gestation. We report three consecutive pregnancies in a patient with glycogen storage disease type IA. The patient, a 35-year-old woman, has been maintained on a regimen of nightly nasogastric or cornstarch feedings for the past 12 years with improving metabolic control, reduced liver size, and no progression of multiple hepatic adenomas. On confirmation of each pregnancy, early in the first trimester nightly feeding was changed from cornstarch ingestion to Polycose by nasogastric intubation, with good metabolic control. During the last trimester of each pregnancy metabolic control showed further improvement, with lowering of lactate, urate, and triglyceride levels. During the first pregnancy unexpected fetal death occurred at 33 weeks. During the last two pregnancies, the patient was admitted at 33 and 34 weeks, respectively, for closer supervision of metabolic status and fetal monitoring. She underwent a cesarean section at 35 weeks 4 days of gestation and was delivered of a girl. She underwent a repeat cesarean section at 35 weeks 2 days for the subsequent gestation and was delivered of a boy. Both infants are healthy and appear to be unaffected by von Gierke's disease. Hepatic adenomas did not enlarge during the pregnancies. Meticulous management resulted in normal pregnancy outcomes in two consecutive gestations. Rapid fetal growth late in the third trimester may require particularly careful supervision to maintain euglycemia. PMID:8203427

  9. Viral Hepatitis

    MedlinePlus

    ... with hepatitis? How does a pregnant woman pass hepatitis B virus to her baby? If I have hepatitis B, what does my baby need so that she ... Can I breastfeed my baby if I have hepatitis B? More information on viral hepatitis What is hepatitis? ...

  10. Muscle glycogen loading with a liquid carbohydrate supplement.

    PubMed

    Lamb, D R; Snyder, A C; Baur, T S

    1991-03-01

    This study compared two high carbohydrate (CHO) diets in 14 male runners for effects on muscle glycogen deposition, endurance, and sensations of gastrointestinal discomfort. Muscle glycogen was measured in the vastus lateralis at rest and run time to exhaustion at 75% VO2max was measured following 3-1/2 days on a 50% CHO diet. After 14 days the subjects consumed a 20% CHO diet and continued training to reduce glycogen. During the next 3-1/2 days, subjects ran less and consumed a 90% CHO diet emphasizing pasta and rice (Pasta, n = 7) or lesser amounts of pasta and rice supplemented by a maltodextrin beverage (Supplement, n = 7). Glycogen was again measured, followed by a second run to exhaustion. Compared to the 50% CHO diet, Pasta increased muscle glycogen by 27.1 +/- 12.2 mmoles/kg muscle (M +/- SE; P < 0.05) and run time by 15.7 +/- 5.9 min; Supplement increased glycogen by 43.2 +/- 13.5 mmoles/kg (P < 0.05) and run time by 29.0 +/- 7.4 min (P < 0.05). Total glycogen concentrations and run times were not significantly different for Pasta versus Supplement. Subjects reported less gastrointestinal discomfort and greater overall preference for Supplement than for Pasta. Thus, glycogen loading can be accomplished at least as effectively and more comfortably by substituting a maltodextrin drink for some of the pasta and rice in a glycogen loading diet. PMID:1844402

  11. Secondary metabolic changes in von Gierke's disease (Type I glycogen storage disease).

    PubMed

    Blackett, P R

    1982-01-01

    Deficiency of glucose-6-phosphatase in Type I glycogen storage disease (GSD) results in hypoglycemia and excessive accumulation of glucose-6-phosphate. As a result, lactic acid, uric acid, and lipids are formed as end-products. The formation of these metabolites are discussed with an emphasis on monitoring therapeutic progress. In addition, hyperlipidemia and associated changes in apolipoproteins are considered as indices of the clinical course. PMID:6753728

  12. Contributions of Glycogen to Astrocytic Energetics during Brain Activation

    PubMed Central

    Dienel, Gerald A.; Cruz, Nancy F.

    2014-01-01

    Glycogen is the major store of glucose in brain and is mainly in astrocytes. Brain glycogen levels in unstimulated, carefully-handled rats are 10-12 mol/g, and assuming that astrocytes account for half the brain mass, astrocytic glycogen content is twice as high. Glycogen turnover is slow under basal conditions, but it is mobilized during activation. There is no net increase in incorporation of label from glucose during activation, whereas label release from pre-labeled glycogen exceeds net glycogen consumption, which increases during stronger stimuli. Because glycogen level is restored by non-oxidative metabolism, astrocytes can influence the global ratio of oxygen to glucose utilization. Compensatory increases in utilization of blood glucose during inhibition of glycogen phosphorylase are large and approximate glycogenolysis rates during sensory stimulation. In contrast, glycogenolysis rates during hypoglycemia are low due to continued glucose delivery and oxidation of endogenous substrates; rates that preserve neuronal function in the absence of glucose are also low, probably due to metabolite oxidation. Modeling studies predict that glycogenolysis maintains a high level of glucose-6-phosphate in astrocytes to maintain feedback inhibition of hexokinase, thereby diverting glucose for use by neurons. The fate of glycogen carbon in vivo is not known, but lactate efflux from brain best accounts for the major metabolic characteristics during activation of living brain. Substantial shuttling coupled with oxidation of glycogen-derived lactate is inconsistent with available evidence. Glycogen has important roles in astrocytic energetics, including glucose sparing, control of extracellular K+ level, oxidative stress management, and memory consolidation; it is a multi-functional compound. PMID:24515302

  13. Globular hepatic amyloid: an early stage in the pathway of amyloid formation: a study of 20 new cases.

    PubMed

    Makhlouf, Hala R; Goodman, Zachary D

    2007-10-01

    Only 25 cases of globular hepatic amyloidosis have been reported, mostly from the early 1980s. We reviewed clinical, histopathologic, and immunohistochemical features of 20 cases of hepatic globular amyloid out of 208 cases of liver amyloidosis seen at the Armed Forces Institute of Pathology since 1970. Fourteen (70%) were men and 6 were women with a median age of 67 years (range, 40 to 92 y). More than half of the patients were Hispanic. Ten of 20 patients were diagnosed with systemic amyloidosis. Histologically, all cases revealed round to oval-shaped sometimes laminated globules, 1 to 40 mum in diameter, and 6 cases had evidence of transition from globular to the more usual linear form. In all 20 cases, Congo red and/or Sirius red stained the globules red and showed an apple green birefringence under polarized light. Portal tracts and parenchyma were involved in 15/20 the cases, and sinusoidal deposition alone in 5 cases. Vascular deposition was very common with more than 3/4 of the cases showing mainly perivenular amyloid with both the terminal hepatic venules and portal vein branches being equally involved. A few intrahepatocellular globules were present in half of the cases. In conclusion, hepatic amyloidosis can rarely occur as a globular form, and the finding of intracellular amyloid globules and transitional forms of globular to linear patterns of deposition suggest that this is an early form of hepatic involvement by systemic amyloidosis. PMID:17895765

  14. A method for the determination of the hepatic enzyme activity catalyzing bile acid acyl glucuronide formation by high-performance liquid chromatography with pulsed amperometric detection.

    PubMed

    Ikegawa, S; Oohashi, J; Murao, N; Goto, J

    2000-05-01

    A method for the determination of the activity of hepatic glucuronyltransferase catalyzing formation of bile acid 24-glucuronides using high-performance liquid chromatography (HPLC) with pulsed amperometric detection (PAD) has been developed. Bile acid 24-glucuronides were simultaneously separated on a semimicrobore column, Capcell Pak C18UG120, using 20 mM ammonium phosphate (pH 6.0)-acetonitrile (27:10 and 16:10) as the mobile phase in the stepwise gradient elution mode. A 1 M potassium hydroxide solution for the hydrolysis of the 24-glucuronides, which liberates the corresponding bile acids and glucuronic acid, was mixed with the mobile phase in a post-column mode, and the resulting eluant was heated at 90 degrees C, the 24-glucuronides being monitored using a pulsed amperometric detector; the limit of detection was 10 ng. The proposed method was applied to the determination of the hepatic enzyme activity catalyzing bile acid 24-glucuronide formation and the result exhibited the efficient 24-glucuronide formation of the monohydroxylated bile acid, lithocholic acid. PMID:10850616

  15. Cx3cr1 deficiency in mice attenuates hepatic granuloma formation during acute schistosomiasis by enhancing the M2-type polarization of macrophages

    PubMed Central

    Ran, Lin; Yu, Qilin; Zhang, Shu; Xiong, Fei; Cheng, Jia; Yang, Ping; Xu, Jun-Fa; Nie, Hao; Zhong, Qin; Yang, Xueli; Yang, Fei; Gong, Quan; Kuczma, Michal; Kraj, Piotr; Gu, Weikuan; Ren, Bo-Xu; Wang, Cong-Yi

    2015-01-01

    ABSTRACT Acute schistosomiasis is characterized by pro-inflammatory responses against tissue- or organ-trapped parasite eggs along with granuloma formation. Here, we describe studies in Cx3cr1−/− mice and demonstrate the role of Cx3cr1 in the pathoetiology of granuloma formation during acute schistosomiasis. Mice deficient in Cx3cr1 were protected from granuloma formation and hepatic injury induced by Schistosoma japonicum eggs, as manifested by reduced body weight loss and attenuated hepatomegaly along with preserved liver function. Notably, S. japonicum infection induced high levels of hepatic Cx3cr1 expression, which was predominantly expressed by infiltrating macrophages. Loss of Cx3cr1 rendered macrophages preferentially towards M2 polarization, which then led to a characteristic switch of the host immune defense from a conventional Th1 to a typical Th2 response during acute schistosomiasis. This immune switch caused by Cx3cr1 deficiency was probably associated with enhanced STAT6/PPAR-γ signaling and increased expression of indoleamine 2,3-dioxygenase (IDO), an enzyme that promotes M2 polarization of macrophages. Taken together, our data provide evidence suggesting that CX3CR1 could be a viable therapeutic target for treatment of acute schistosomiasis. PMID:26035381

  16. Genetics Home Reference: glycogen storage disease type 0

    MedlinePlus

    ... the expand/collapse boxes. Download PDF Open All Close All Description Glycogen storage disease type 0 (also known as GSD 0) is a condition caused by the body's inability to form a complex sugar called glycogen , which is a major source of stored energy in the body. GSD 0 ...

  17. Muscle glycogen and cell function--Location, location, location.

    PubMed

    Ørtenblad, N; Nielsen, J

    2015-12-01

    The importance of glycogen, as a fuel during exercise, is a fundamental concept in exercise physiology. The use of electron microscopy has revealed that glycogen is not evenly distributed in skeletal muscle fibers, but rather localized in distinct pools. In this review, we present the available evidence regarding the subcellular localization of glycogen in skeletal muscle and discuss this from the perspective of skeletal muscle fiber function. The distribution of glycogen in the defined pools within the skeletal muscle varies depending on exercise intensity, fiber phenotype, training status, and immobilization. Furthermore, these defined pools may serve specific functions in the cell. Specifically, reduced levels of these pools of glycogen are associated with reduced SR Ca(2+) release, muscle relaxation rate, and membrane excitability. Collectively, the available literature strongly demonstrates that the subcellular localization of glycogen has to be considered to fully understand the role of glycogen metabolism and signaling in skeletal muscle function. Here, we propose that the effect of low muscle glycogen on excitation-contraction coupling may serve as a built-in mechanism, which links the energetic state of the muscle fiber to energy utilization. PMID:26589115

  18. Mechanism of glycogen supercompensation in rat skeletal muscle cultures.

    PubMed

    Mamedova, Liaman K; Shneyvays, Vladimir; Katz, Abram; Shainberg, Asher

    2003-08-01

    A model to study glycogen supercompensation (the significant increase in glycogen content above basal level) in primary rat skeletal muscle culture was established. Glycogen was completely depleted in differentiated myotubes by 2 h of electrical stimulation or exposure to hypoxia during incubation in medium devoid of glucose. Thereafter, cells were incubated in medium containing glucose, and glycogen supercompensation was clearly observed in treated myotubes after 72 h. Peak glycogen levels were obtained after 120 h, averaging 2.5 and 4 fold above control values in the stimulated- and hypoxia-treated cells, respectively. Glycogen synthase activity increased and phosphorylase activity decreased continuously during 120 h of recovery in the treated cells. Rates of 2-deoxyglucose uptake were significantly elevated in the treated cells at 96 and 120 h, averaging 1.4-2 fold above control values. Glycogenin content increased slightly in the treated cells after 48 h (1.2 fold vs. control) and then increased considerably, achieving peak values after 120 h (2 fold vs. control). The results demonstrate two phases of glycogen supercompensation: the first phase depends primarily on activation of glycogen synthase and inactivation of phosphorylase; the second phase includes increases in glucose uptake and glycogenin level. PMID:12962138

  19. Structural basis for the recruitment of glycogen synthase by glycogenin

    PubMed Central

    Zeqiraj, Elton; Tang, Xiaojing; Hunter, Roger W.; García-Rocha, Mar; Judd, Andrew; Deak, Maria; von Wilamowitz-Moellendorff, Alexander; Kurinov, Igor; Guinovart, Joan J.; Tyers, Mike; Sakamoto, Kei; Sicheri, Frank

    2014-01-01

    Glycogen is a primary form of energy storage in eukaryotes that is essential for glucose homeostasis. The glycogen polymer is synthesized from glucose through the cooperative action of glycogen synthase (GS), glycogenin (GN), and glycogen branching enzyme and forms particles that range in size from 10 to 290 nm. GS is regulated by allosteric activation upon glucose-6-phosphate binding and inactivation by phosphorylation on its N- and C-terminal regulatory tails. GS alone is incapable of starting synthesis of a glycogen particle de novo, but instead it extends preexisting chains initiated by glycogenin. The molecular determinants by which GS recognizes self-glucosylated GN, the first step in glycogenesis, are unknown. We describe the crystal structure of Caenorhabditis elegans GS in complex with a minimal GS targeting sequence in GN and show that a 34-residue region of GN binds to a conserved surface on GS that is distinct from previously characterized allosteric and binding surfaces on the enzyme. The interaction identified in the GS-GN costructure is required for GS–GN interaction and for glycogen synthesis in a cell-free system and in intact cells. The interaction of full-length GS-GN proteins is enhanced by an avidity effect imparted by a dimeric state of GN and a tetrameric state of GS. Finally, the structure of the N- and C-terminal regulatory tails of GS provide a basis for understanding phosphoregulation of glycogen synthesis. These results uncover a central molecular mechanism that governs glycogen metabolism. PMID:24982189

  20. Ontogeny of the rat hepatic adrenoceptors

    SciTech Connect

    McMillian, M.K.

    1985-01-01

    Hepatic alpha-1, alpha-2, and beta-2 adrenoceptors were characterized during development of the rat through Scatchard analysis of (/sup 3/H)-prazosin, (/sup 3/H)-rauwolscine and (/sup 125/I)-pindolol binding to washed particle membrane preparations. Major changes in adrenoceptor number occur shortly before birth and at weaning. The fetal rat liver is characterized by a large number of alpha-2 adrenoceptors which falls 10-20 fold at birth. The number of hepatic beta adrenoceptors decreases 30-50% during the third week after birth increases slightly at weaning, then decreases gradually in the adult. Hepatic alpha-1 adrenoceptor number increases 3-5 fold at weaning to become the predominant adrenoceptor in the adult rat liver. The basis for the fall in alpha-2 number at birth remains unclear. The fall in beta receptor number at the end of the second week post-natally appears dependent on increased insulin and corticosterone secretion as well as increased NE release form nerve terminals. The basis for the increase in beta number at weaning and the sex-dependent loss of beta function but not receptor number in the adult rat remains unknown. The dramatic increases in alpha-1 number and function at weaning are dependent on increased adrenocortical secretion, adrenalectomy prevents the normal. This effect of adrenocorticoids might be mediated through glycogen, as glycogen depletion during fasting decreases alpha-1 receptor number and function at weaning are dependent on increased adrenocortical secretion, adrenalectomy prevents the normal. This effect of adrenocorticoids might be mediated through glycogen, as glycogen depletion during fasting decreases alpha-1 receptor number and function. These findings suggest that hepatic adrenoceptor number adapts from the low carbohydrate diet of the suckling rat to the high carbohydrate diet of the adult at weaning.

  1. Effect of exhaustive ultra-endurance exercise in muscular glycogen and both Alpha1 and Alpha2 Ampk protein expression in trained rats.

    PubMed

    Tarini, V A F; Carnevali, L C; Arida, R M; Cunha, C A; Alves, E S; Seeleander, M C L; Schmidt, B; Faloppa, F

    2013-09-01

    Glycogen is the main store of readily energy in skeletal muscle and plays a key role in muscle function, demonstrated by the inability to sustain prolonged high-intensity exercise upon depletion of these glycogen stores. With prolonged exercise, glycogen depletion occurs and 5'-AMP-activated protein kinase (AMPK), a potent regulator of muscle metabolism and gene expression, is activated promoting molecular signalling that increases glucose uptake by muscular skeletal cells. The aim of this study was primarily to determine the effect of ultra-endurance exercise on muscle glycogen reserves and secondly to verify the influence of this type of exercise on AMPK protein expression. Twenty-four male Wistar rats, 60 days old, were divided into four experimental groups: sedentary, sedentary exhausted (SE), endurance trained (T) and endurance trained exhausted (TE). The animals ran for 10 to 90 min/day, 5 days/week, for 12 weeks to attain trained status. Rats were killed immediately after the exhaustion protocol, which consisted of running on a treadmill (at approximately 60% Vmax until exhaustion). Optical density of periodic acid-Schiff was detected and glycogen depletion observed predominantly in type I muscle fibres of the TE group and in both type I and II muscle fibres in the SE group. Plasma glucose decreased only in the TE group. Hepatic glycogen was increased in T group and significantly depleted in TE group. AMPK protein expression was significantly elevated in TE and T groups. In conclusion, acute exhaustive ultra-endurance exercise promoted muscle glycogen depletion. It seems that total AMPK protein and gene expression is more influenced by status training. PMID:23184732

  2. The effect of pulp and seed extract of Citrullus Colocynthis, as an antidaibetic medicinal herb, on hepatocytes glycogen stores in diabetic rabbits

    PubMed Central

    Shafaei, Hajar; Rad, Jafar Soleimani; Delazar, Abbas; Behjati, Mohaddeseh

    2014-01-01

    Background: Medicinal herbs such as Citrullus Colocynthis (C.C) have been used traditionally in the treatment of diabetes mellitus. However therapeutic applications and adverse effects of C.C and its natural variants are not determined well. The current work investigates the effects of pulp and seed extract of C.C on hepatocyte's glycogen stores. Materials and Methods: Thirty six male rabbits were divided into six groups (control and diabetic) randomly. Alloxan was used in order to induce diabetes mellitus in animals. Among 5 diabetic groups, one remained as control and the rest received 100 and 200 mg/kg/day of either pulp or seed extract. One month later, animals were sacrificed and their liver specimen fixed in 10% Formalin was stained with periodic acid schiff (PAS) for light microscopic scanning. Results: PAS staining of hepatocytes revealed large amounts of glycogen stores in diabetic animals treated with pulp and seed extracts of C.C, contrary with non-treated diabetic rabbits. Sites of glycogen deposition were also different in animals treated with seed extract (P < 0.0001). No hepatic congestion was seen in treated animals. Dose escalation has no effect on the obtained results. Conclusions: The anti-diabetic effects of C.C can be explained by its effects on accumulation of glycogen stores in hepatocytes. The importance of varied sites of glycogen deposition by the application of C.C needs to be determined. PMID:25625097

  3. The design of potential antidiabetic drugs: experimental investigation of a number of beta-D-glucose analogue inhibitors of glycogen phosphorylase.

    PubMed

    Oikonomakos, N G; Kontou, M; Zographos, S E; Tsitoura, H S; Johnson, L N; Watson, K A; Mitchell, E P; Fleet, G W; Son, J C; Bichard, C J

    1994-01-01

    alpha-D-glucose is a weak inhibitor (Ki = 1.7 mM) of glycogen phosphorylase (GP) and acts as physiological regulator of hepatic glycogen metabolism; it binds to GP at the catalytic site and stabilizes the inactive T state of the enzyme promoting the action of protein phosphatase 1 and stimulating glycogen synthase. The three-dimensional structures of T state rabbit muscle GPb and the GPb-alpha-D-glucose complex have been exploited in the design of better regulators of GP that could shift the balance between glycogen synthesis and glycogen degradation in favour of the former. Close examination of the catalytic site with alpha-D-glucose bound shows that there is an empty pocket adjacent to the beta-1-C position. beta-D-glucose is a poorer inhibitor (Ki = 7.4 mM) than alpha-D-glucose, but mutarotation has prevented the binding of beta-D-glucose in T state GP crystals. A series of beta-D-glucose analogues has been designed and tested in kinetic and crystallographic experiments. Several compounds have been discovered that have an increased affinity for GP than the parent compound. PMID:7867660

  4. Quantifying the Contribution of the Liver to Glucose Homeostasis: A Detailed Kinetic Model of Human Hepatic Glucose Metabolism

    PubMed Central

    König, Matthias; Bulik, Sascha; Holzhütter, Hermann-Georg

    2012-01-01

    Despite the crucial role of the liver in glucose homeostasis, a detailed mathematical model of human hepatic glucose metabolism is lacking so far. Here we present a detailed kinetic model of glycolysis, gluconeogenesis and glycogen metabolism in human hepatocytes integrated with the hormonal control of these pathways by insulin, glucagon and epinephrine. Model simulations are in good agreement with experimental data on (i) the quantitative contributions of glycolysis, gluconeogenesis, and glycogen metabolism to hepatic glucose production and hepatic glucose utilization under varying physiological states. (ii) the time courses of postprandial glycogen storage as well as glycogen depletion in overnight fasting and short term fasting (iii) the switch from net hepatic glucose production under hypoglycemia to net hepatic glucose utilization under hyperglycemia essential for glucose homeostasis (iv) hormone perturbations of hepatic glucose metabolism. Response analysis reveals an extra high capacity of the liver to counteract changes of plasma glucose level below 5 mM (hypoglycemia) and above 7.5 mM (hyperglycemia). Our model may serve as an important module of a whole-body model of human glucose metabolism and as a valuable tool for understanding the role of the liver in glucose homeostasis under normal conditions and in diseases like diabetes or glycogen storage diseases. PMID:22761565

  5. Supercompensated glycogen loads persist 5 days in resting trained cyclists.

    PubMed

    Arnall, David A; Nelson, Arnold G; Quigley, Jack; Lex, Stephen; Dehart, Tom; Fortune, Peggy

    2007-02-01

    Research data indicates a persistence of elevated muscle glycogen concentration 3 days post-supercompensation in resting athletes. This study expands our earlier findings by determining whether muscle glycogen remains elevated 3, 5, or 7 days post-supercompensation. Seventeen trained male cyclists underwent one bout of exhaustive exercise to deplete muscle glycogen. This was followed by a 3-day consumption of a high carbohydrate/low protein/low fat diet (85:08:07%). Three post-loading phases followed with subjects randomly assigned to either a 3-day, 5-day, or 7-day post-loading maintenance diet of 60% carbohydrate and limited physical activity. Biopsies (50-150 mg) of the vastus lateralis were obtained pre-load (BASELINE), at peak-load (PEAK), and either at 3-day, 5-day, or 7-day post-load (POST). On average, PEAK to POST muscle glycogen concentrations decreased 34, 20 and 46% respectively for the 3-, 5-, and 7-day POST groups. Only the 7-day post-load group's PEAK to POST mean muscle glycogen concentration decreased significantly. In addition, multi-regression analysis indicated that the PEAK glycogen level was the main determinant of the number of days that glycogen levels remained significantly greater than BASELINE. Thus, trained athletes' supercompensated glycogen levels can remain higher than normal for up to 5 days post-loading. The amount of carbohydrate consumed, the level of physical activity, and the magnitude of the glycogen supercompensation determine the interval for which the glycogen levels are elevated. PMID:17120016

  6. The Phospholipid:Diacylglycerol Acyltransferase Lro1 Is Responsible for Hepatitis C Virus Core-Induced Lipid Droplet Formation in a Yeast Model System

    PubMed Central

    Wang, Chao-Wen; Cheng, Yun-Hsin; Irokawa, Hayato; Hwang, Gi-Wook; Naganuma, Akira; Kuge, Shusuke

    2016-01-01

    Chronic infection with the hepatitis C virus frequently induces steatosis, which is a significant risk factor for liver pathogenesis. Steatosis is characterized by the accumulation of lipid droplets in hepatocytes. The structural protein core of the virus induces lipid droplet formation and localizes on the surface of the lipid droplets. However, the precise molecular mechanisms for the core-induced formation of lipid droplets remain elusive. Recently, we showed that the expression of the core protein in yeast as a model system could induce lipid droplet formation. In this study, we probed the cellular factors responsible for the formation of core-induced lipid-droplets in yeast cells. We demonstrated that one of the enzymes responsible for triglyceride synthesis, a phospholipid:diacylglycerol acyltransferase (Lro1), is required for the core-induced lipid droplet formation. While core proteins inhibit Lro1 degradation and alter Lro1 localization, the characteristic localization of Lro1 adjacent to the lipid droplets appeared to be responsible for the core-induced lipid droplet formation. RNA virus genomes have evolved using high mutation rates to maintain their ability to replicate. Our observations suggest a functional relationship between the core protein with hepatocytes and yeast cells. The possible interactions between core proteins and the endoplasmic reticulum membrane affect the mobilization of specific proteins. PMID:27459103

  7. Methodological and physiological test-retest reliability of (13) C-MRS glycogen measurements in liver and in skeletal muscle of patients with type 1 diabetes and matched healthy controls.

    PubMed

    Buehler, Tania; Bally, Lia; Dokumaci, Ayse Sila; Stettler, Christoph; Boesch, Chris

    2016-06-01

    Glycogen is a major substrate in energy metabolism and particularly important to prevent hypoglycemia in pathologies of glucose homeostasis such as type 1 diabetes mellitus (T1DM). (13) C-MRS is increasingly used to determine glycogen in skeletal muscle and liver non-invasively; however, the low signal-to-noise ratio leads to long acquisition times, particularly when glycogen levels are determined before and after interventions. In order to ease the requirements for the subjects and to avoid systematic effects of the lengthy examination, we evaluated if a standardized preparation period would allow us to shift the baseline (pre-intervention) experiments to a preceding day. Based on natural abundance (13) C-MRS on a clinical 3 T MR system the present study investigated the test-retest reliability of glycogen measurements in patients with T1DM and matched controls (n = 10 each group) in quadriceps muscle and liver. Prior to the MR examination, participants followed a standardized diet and avoided strenuous exercise for two days. The average coefficient of variation (CV) of myocellular glycogen levels was 9.7% in patients with T1DM compared with 6.6% in controls after a 2 week period, while hepatic glycogen variability was 13.3% in patients with T1DM and 14.6% in controls. For comparison, a single-session test-retest variability in four healthy volunteers resulted in 9.5% for skeletal muscle and 14.3% for liver. Glycogen levels in muscle and liver were not statistically different between test and retest, except for hepatic glycogen, which decreased in T1DM patients in the retest examination, but without an increase of the group distribution. Since the CVs of glycogen levels determined in a "single session" versus "within weeks" are comparable, we conclude that the major source of uncertainty is the methodological error and that physiological variations can be minimized by a pre-study standardization. For hepatic glycogen examinations, familiarization sessions

  8. Sequestration of neutrophils in the hepatic vasculature during endotoxemia is independent of beta 2 integrins and intercellular adhesion molecule-1.

    PubMed

    Jaeschke, H; Farhood, A; Fisher, M A; Smith, C W

    1996-11-01

    Antibodies against cellular adhesion molecules protect against neutrophil-induced hepatic injury during ischemia-reperfusion and endotoxemia. To test if beta 2 integrins on neutrophils and intercellular adhesion molecule-1 (ICAM-1) on endothelial cells are involved in neutrophil sequestration in the hepatic vasculature, neutrophil accumulation in the liver was characterized during the early phase of endotoxemia. Intravenous injection of Salmonella enteritidis endotoxin induced a dose-dependent activation of complement, tumor necrosis factor-alpha (TNF-alpha) formation, and an increase of hepatic neutrophils with maximal numbers at 5 mg/kg (90 min: 339 +/- 14 cells/50 high power fields; controls: 18 +/- 2). Administration of 15 micrograms/kg TNF-alpha and intravascular complement activation with cobra venom factor (75 micrograms/kg) had additive effects on hepatic neutrophil accumulation compared with each mediator alone. Monoclonal antibodies (2 mg/kg) to ICAM-1 and the alpha-chain (CD11a, CD11b) or the beta-chain (CD18) of beta 2 integrins had no significant effect on hepatic neutrophil count after endotoxin. In contrast, these antibodies inhibited peritoneal neutrophil infiltration in response to glycogen administration by 28% (CD11b), 60% (CD11a, ICAM-1), and 92% (CD18). Our data suggest that TNF-alpha and complement factors contribute to hepatic neutrophil sequestration during the early phase of endotoxemia. Despite the fact that these inflammatory mediators can up-regulate integrins and ICAM-1, these adhesion molecules are not necessary for neutrophil accumulation in hepatic sinusoids. The protective effect of these antibodies against neutrophil-induced liver injury appears to be due to inhibition of transendothelial migration and adherence to parenchymal cells. PMID:8946651

  9. Mono-(2-ethylhexyl) phthalate targets glycogen debranching enzyme and affects glycogen metabolism in rat testis.

    PubMed

    Kuramori, Chikanori; Hase, Yasuyoshi; Hoshikawa, Koichi; Watanabe, Keiko; Nishi, Takeyuki; Hishiki, Takako; Soga, Tomoyoshi; Nashimoto, Akihiro; Kabe, Yasuaki; Yamaguchi, Yuki; Watanabe, Hajime; Kataoka, Kohsuke; Suematsu, Makoto; Handa, Hiroshi

    2009-05-01

    Phthalate esters are commonly used plasticizers; however, some are suspected to cause reproductive toxicity. Administration of high doses of di-(2-ethylhexyl) phthalate (DEHP) induces germ cell death in male rodents. Mono-(2-ethylhexyl) phthalate (MEHP), a hydrolyzed metabolite of DEHP, appears to be responsible for this testicular toxicity; however, the underlying mechanism of this chemical's action remains unknown. Here, using a one-step affinity purification procedure, we identified glycogen debranching enzyme (GDE) as a phthalate-binding protein. GDE has oligo-1,4-1,4-glucanotransferase and amylo-1,6-glucosidase activities, which are responsible for the complete degradation of glycogen to glucose. Our findings demonstrate that MEHP inhibits the activity of oligo-1,4-1,4-glucanotransferase, but not of amylo-1,6-glucosidase. Among various phthalate esters tested, MEHP specifically binds to and inhibits GDE. We also show that DEHP administration affects glycogen metabolism in rat testis. Thus, inhibition of GDE by MEHP may play a role in germ cell apoptosis in the testis. PMID:19240039

  10. Glycogen repletion following continuous and intermittent exercise to exhaustion.

    PubMed

    Gaesser, G A; Brooks, G A

    1980-10-01

    Patterns of postexercise glycogen repletion in heart, skeletal muscle, and liver in the absence of exogenously supplied substrates during the first 4 h of recovery were assessed. Female Wistar rats were run to exhaustion using continuous (1.0 mph, 15% grade) and intermittent (alternate 1-min intervals at 0.5 and 1.5 mph, 15% grade) exercise protocols. Rats at exhaustion were characterized by marked depletion of glycogen in heart (55%), skeletal muscle (94%), and liver (97%). Blood glucose levels at exhaustion (1.33 mumol/g) were only 37% of preexercise levels. There were no significant differences between continuous and intermittent exercise groups for any of the tissue glycogen or blood glucose values. Cardiac muscle was the only tissue capable of complete restoration of glycogen levels while relying exclusively upon endogenous substrates. Concentrations of endogenous substrates present at the end of exercise were insufficient to support restoration of blood glucose levels to preexercise values nor support glycogen repletion in skeletal muscle and liver during the initial 4-h food-restricted postexercise period. With subsequent feeding, skeletal muscle demonstrated a glycogen supercompensation effect at 24 h (181.1 and 191.8% of preexercise levels for continuous and intermittent exercise, respectively). Lactate concentration in all tissues at the point exhaustion (1.5--2.5 times resting levels) were only moderately elevated and returned to preexercise levels within 15 min. It was concluded that lactate removal after exercise contributed only minimally to the repletion of muscle glycogen. PMID:7440286

  11. Transient Hepatic Overexpression of Insulin-Like Growth Factor 2 Induces Free Cholesterol and Lipid Droplet Formation.

    PubMed

    Kessler, Sonja M; Laggai, Stephan; Van Wonterg, Elien; Gemperlein, Katja; Müller, Rolf; Haybaeck, Johannes; Vandenbroucke, Roosmarijn E; Ogris, Manfred; Libert, Claude; Kiemer, Alexandra K

    2016-01-01

    Although insulin-like growth factor 2 (IGF2) has been reported to be overexpressed in steatosis and steatohepatitis, a causal role of IGF2 in steatosis development remains elusive. Aim of our study was to decipher the role of IGF2 in steatosis development. Hydrodynamic gene delivery of an Igf2 plasmid used for transient Igf2 overexpression employing codon-optimized plasmid DNA resulted in a strong induction of hepatic Igf2 expression. The exogenously delivered Igf2 had no influence on endogenous Igf2 expression. The downstream kinase AKT was activated in Igf2 animals. Decreased ALT levels mirrored the cytoprotective effect of IGF2. Serum cholesterol was increased and sulfo-phospho-vanillin colorimetric assay confirmed lipid accumulation in Igf2-livers while no signs of inflammation were observed. Interestingly, hepatic cholesterol and phospholipids, determined by thin layer chromatography, and free cholesterol by filipin staining, were specifically increased. Lipid droplet (LD) size was not changed, but their number was significantly elevated. Furthermore, free cholesterol, which can be stored in LDs and has been reported to be critical for steatosis progression, was elevated in Igf2 overexpressing mice. Accordingly, Hmgcr/HmgCoAR was upregulated. To have a closer look at de novo lipid synthesis we investigated expression of the lipogenic transcription factor SREBF1 and its target genes. SREBF1 was induced and also SREBF1 target genes were slightly upregulated. Interestingly, the expression of Cpt1a, which is responsible for mitochondrial fatty acid oxidation, was induced. Hepatic IGF2 expression induces a fatty liver, characterized by increased cholesterol and phospholipids leading to accumulation of LDs. We therefore suggest a causal role for IGF2 in hepatic lipid accumulation. PMID:27199763

  12. Evolution of Hepatic Steatosis to Fibrosis and Adenoma Formation in Liver-Specific Growth Hormone Receptor Knockout Mice

    PubMed Central

    Fan, Yong; Fang, Xin; Tajima, Asako; Geng, Xuehui; Ranganathan, Sarangarajan; Dong, Henry; Trucco, Massimo; Sperling, Mark A.

    2014-01-01

    Background: Non-alcoholic fatty liver disease (NAFLD) is one of the most common forms of chronic liver diseases closely associated with obesity and insulin resistance; deficient growth hormone (GH) action in liver has been implicated as a mechanism. Here, we investigated the evolution of NAFLD in aged mice with liver-specific GHR deletion. Methods: We examined glucose tolerance, insulin responsiveness, and lipid profiles in aged male mice (44–50 weeks) with GHRLD. We performed proteomics analysis, pathway-based Superarray assay, as well as quantitative RT-PCR to gain molecular insight into the mechanism(s) of GHR-deficiency-mediated NAFLD. In addition, we examined the pathological changes of livers of aged GHRLD male mice. Results: The biochemical profile was consistent with that of the metabolic syndrome: abnormal glucose tolerance, impaired insulin secretion, and hyperlipidemia. RT-qPCR analysis of key markers of inflammation revealed a three- to fivefold increase in TNFα and CCL3, confirming the presence of inflammation. Expression of fibrotic markers (e.g., Col1A2 and Col3A1) was significantly increased, together with a two- to threefold increase in TGFβ transcripts. Proteomics analyses showed a marked decrease of Mup1 and Selenbp2. In addition, pathway-analysis showed that the expression of cell cycle and growth relevant genes (i.e., Ccnd1, Socs2, Socs3, and Egfr) were markedly affected in GHRLD liver. Microscopic analyses (H&E) of GHRLD livers revealed the presence of hepatic adenomas of different stages of malignancy. Conclusion: Abrogation of GH signaling in male liver leads to metabolic syndrome, hepatic steatosis, increased inflammation and fibrosis, and development of hepatic tumor. Since obesity, a common precursor of NAFLD, is a state of deficient GH secretion and action, the GHRLD model could be used to unravel the contribution of compromised hepatic GH signaling in these pathological processes, and help to identify potential targets for

  13. Transient Hepatic Overexpression of Insulin-Like Growth Factor 2 Induces Free Cholesterol and Lipid Droplet Formation

    PubMed Central

    Kessler, Sonja M.; Laggai, Stephan; Van Wonterghem, Elien; Gemperlein, Katja; Müller, Rolf; Haybaeck, Johannes; Vandenbroucke, Roosmarijn E.; Ogris, Manfred; Libert, Claude; Kiemer, Alexandra K.

    2016-01-01

    Although insulin-like growth factor 2 (IGF2) has been reported to be overexpressed in steatosis and steatohepatitis, a causal role of IGF2 in steatosis development remains elusive. Aim of our study was to decipher the role of IGF2 in steatosis development. Hydrodynamic gene delivery of an Igf2 plasmid used for transient Igf2 overexpression employing codon-optimized plasmid DNA resulted in a strong induction of hepatic Igf2 expression. The exogenously delivered Igf2 had no influence on endogenous Igf2 expression. The downstream kinase AKT was activated in Igf2 animals. Decreased ALT levels mirrored the cytoprotective effect of IGF2. Serum cholesterol was increased and sulfo-phospho-vanillin colorimetric assay confirmed lipid accumulation in Igf2-livers while no signs of inflammation were observed. Interestingly, hepatic cholesterol and phospholipids, determined by thin layer chromatography, and free cholesterol by filipin staining, were specifically increased. Lipid droplet (LD) size was not changed, but their number was significantly elevated. Furthermore, free cholesterol, which can be stored in LDs and has been reported to be critical for steatosis progression, was elevated in Igf2 overexpressing mice. Accordingly, Hmgcr/HmgCoAR was upregulated. To have a closer look at de novo lipid synthesis we investigated expression of the lipogenic transcription factor SREBF1 and its target genes. SREBF1 was induced and also SREBF1 target genes were slightly upregulated. Interestingly, the expression of Cpt1a, which is responsible for mitochondrial fatty acid oxidation, was induced. Hepatic IGF2 expression induces a fatty liver, characterized by increased cholesterol and phospholipids leading to accumulation of LDs. We therefore suggest a causal role for IGF2 in hepatic lipid accumulation. PMID:27199763

  14. The Transcriptional Profiling of Glycogenes Associated with Hepatocellular Carcinoma Metastasis

    PubMed Central

    Liu, Tianhua; Zhang, Shu; Chen, Jie; Jiang, Kai; Zhang, Qinle; Guo, Kun; Liu, Yinkun

    2014-01-01

    Background and objective Metastasis is one of the important reasons for the poor prognosis of hepatocellular carcinoma (HCC), abnormal glycosylation plays a pivotal role in HCC metastasis. The goal of this study was to screen and validate the transcriptional profiling of glycogenes associated with HCC metastasis. Methodology The differentially transcribed glycogenes were screened out by the Human Glycosylation RT2 Profiler PCR Array, and were identified by qRT-PCR in human HCC cell lines and their orthotopic xenograft tumors. Further analyses were performed with K-mean clustering, Gene Ontology (GO) and ingenuity pathways analysis (IPA). Four differentially transcribed glycogenes were validated in clinical cancer specimens by qRT-PCR. Results A total of thirty-three differentially transcribed glycogenes were obtained by comparison the transcription in the metastatic human HCC cell lines (MHCC97L, MHCC97H and HCCLM3) with the transcription in the non-metastatic HCC cell line Hep3B. Seven differentially transcribed glycogenes were selected to further identification in human HCC cell lines and their orthotopic xenograft tumors. According to their trends by K-mean clustering, all of the differentially transcribed glycogenes were classified in six clusters. GO analysis of the differentially transcribed glycogenes described them in biological process, subcellular location and molecular function. Furthermore, the partial regulatory network of the differentially transcribed glycogenes was acquired through the IPA. The transcription levels of galnt3, gcnt3, man1a1, mgat5b in non-metastatic and metastatic HCC clinical cancer specimens showed the same changing trends with the results in human HCC cell lines and their orthotopic xenograft tumors, and the divergent transcription levels of gcnt3 and mgat5b were statistically significant. Conclusions The transcriptional profiling of glycogenes associated with HCC metastasis was obtained and validated in this study and it might

  15. Glycogen Phosphorylase in Acanthamoeba spp.: Determining the Role of the Enzyme during the Encystment Process Using RNA Interference▿

    PubMed Central

    Lorenzo-Morales, Jacob; Kliescikova, Jarmila; Martinez-Carretero, Enrique; De Pablos, Luis Miguel; Profotova, Bronislava; Nohynkova, Eva; Osuna, Antonio; Valladares, Basilio

    2008-01-01

    Acanthamoeba infections are difficult to treat due to often late diagnosis and the lack of effective and specific therapeutic agents. The most important reason for unsuccessful therapy seems to be the existence of a double-wall cyst stage that is highly resistant to the available treatments, causing reinfections. The major components of the Acanthamoeba cyst wall are acid-resistant proteins and cellulose. The latter has been reported to be the major component of the inner cyst wall. It has been demonstrated previously that glycogen is the main source of free glucose for the synthesis of cellulose in Acanthamoeba, partly as glycogen levels fall during the encystment process. In other lower eukaryotes (e.g., Dictyostelium discoideum), glycogen phosphorylase has been reported to be the main tool used for glycogen breakdown in order to maintain the free glucose levels during the encystment process. Therefore, it was hypothesized that the regulation of the key processes involved in the Acanthamoeba encystment may be similar to the previously reported regulation mechanisms in other lower eukaryotes. The catalytic domain of the glycogen phosphorylase was silenced using RNA interference methods, and the effect of this phenomenon was assessed by light and electron microscopy analyses, calcofluor staining, expression zymogram assays, and Northern and Western blot analyses of both small interfering RNA-treated and control cells. The present report establishes the role of glycogen phosphorylase during the encystment process of Acanthamoeba. Moreover, the obtained results demonstrate that the enzyme is required for cyst wall assembly, mainly for the formation of the cell wall inner layer. PMID:18223117

  16. Glycogen is a preferred glutamate precursor during learning in 1-day-old chick: biochemical and behavioral evidence.

    PubMed

    Gibbs, Marie E; Lloyd, Hilary G E; Santa, Thomas; Hertz, Leif

    2007-11-15

    Bead discrimination training in chicks sets in motion a tightly timed series of biochemical events, including glutamate release, increase in forebrain level of glutamate and utilization of glycogen and glucose. Inhibition of glycogen breakdown by the glycogen phosphorylase inhibitor 1,4-dideoxy-1,4-imino-D-arabinitol (DAB) around the time of training abolishes the increase in glutamate 5 min posttraining in the left hemisphere, in spite of uninhibited glucose metabolism. It also reduces the contents of glutamate, glutamine, and aspartate in the right hemisphere. Behavioral evidence supports the conclusion that glucose breakdown serves to provide energy, whereas glycogen acts as a substrate for glutamate, glutamine, and aspartate formation, requiring both pyruvate dehydrogenation to acetyl coenzyme A and pyruvate carboxylation in astrocytes. Inhibition of memory consolidation caused by DAB or 2-deoxyglucose (2-DG), an inhibitor of glucose phosphorylation without effect on glycogen metabolism, was challenged by intracerebral administration of acetate, aspartate, glutamine, lactate or glucose. DAB-mediated memory inhibition was successfully challenged by administration at 0 or 20 min posttraining of acetate (an astrocyte-specific acetyl CoA precursor) together with aspartate, substituting for pyruvate carboxylation, or of glutamine at 0-2.5 or 30 min posttraining. 2-DG-mediated memory impairment was not challenged by acetate with or without aspartate at 0 time but was challenged by acetate without aspartate at 20 min. Lactate, a substrate for both dehydrogenation and pyruvate carboxylation challenged both DAB and 2-DG. Doses of DAB and 2-DG which, on their own were subeffective, were not additive, further supporting the existence of one pathway using glucose and another using glycogen. PMID:17455305

  17. Kinetic and crystallographic studies of glucopyranose spirohydantoin and glucopyranosylamine analogs inhibitors of glycogen phosphorylase.

    PubMed

    Watson, Kimberly A; Chrysina, Evangelia D; Tsitsanou, Katerina E; Zographos, Spyros E; Archontis, Georgios; Fleet, George W J; Oikonomakos, Nikos G

    2005-12-01

    Glycogen phosphorylase (GP) is currently exploited as a target for inhibition of hepatic glycogenolysis under high glucose conditions. Spirohydantoin of glucopyranose and N-acetyl-beta-D-glucopyranosylamine have been identified as the most potent inhibitors of GP that bind at the catalytic site. Four spirohydantoin and three beta-D-glucopyranosylamine analogs have been designed, synthesized and tested for inhibition of GP in kinetic experiments. Depending on the functional group introduced, the K(i) values varied from 16.5 microM to 1200 microM. In order to rationalize the kinetic results, we determined the crystal structures of the analogs in complex with GP. All the inhibitors bound at the catalytic site of the enzyme, by making direct and water-mediated hydrogen bonds with the protein and by inducing minor movements of the side chains of Asp283 and Asn284, of the 280s loop that blocks access of the substrate glycogen to the catalytic site, and changes in the water structure in the vicinity of the site. The differences observed in the Ki values of the analogs can be interpreted in terms of variations in hydrogen bonding and van der Waals interactions, desolvation effects, ligand conformational entropy, and displacement of water molecules on ligand binding to the catalytic site. PMID:16222658

  18. Fgk3 glycogen synthase kinase is important for development, pathogenesis, and stress responses in Fusarium graminearum.

    PubMed

    Qin, Jun; Wang, Guanghui; Jiang, Cong; Xu, Jin-Rong; Wang, Chenfang

    2015-01-01

    Wheat scab caused by Fusarium graminearum is an important disease. In a previous study, the FGK3 glycogen synthase kinase gene orthologous to mammalian GSK3 was identified as an important virulence factor. Although GSK3 orthologs are well-conserved, none of them have been functionally characterized in fungal pathogens. In this study, we further characterized the roles of FGK3 gene. The Δfgk3 mutant had pleiotropic defects in growth rate, conidium morphology, germination, and perithecium formation. It was non-pathogenic in infection assays and blocked in DON production. Glycogen accumulation was increased in the Δfgk3 mutant, confirming the inhibitory role of Fgk3 on glycogen synthase. In FGK3-GFP transformants, GFP signals mainly localized to the cytoplasm in conidia but to the cytoplasm and nucleus in hyphae. Moreover, the expression level of FGK3 increased in response to cold, H2O2, and SDS stresses. In the Δfgk3 mutant, cold, heat, and salt stresses failed to induce the expression of the stress response-related genes FgGRE2, FgGPD1, FgCTT1, and FgMSN2. In the presence of 80 mM LiCl, a GSK3 kinase inhibitor, the wild type displayed similar defects to the Δfgk3 mutant. Overall, our results indicate that FGK3 is important for growth, conidiogenesis, DON production, pathogenicity, and stress responses in F. graminearum. PMID:25703795

  19. Hepatitis virus panel

    MedlinePlus

    Hepatitis A antibody test; Hepatitis B antibody test; Hepatitis C antibody test; Hepatitis D antibody test ... or past infection, or immunity to hepatitis A Hepatitis B tests: Hepatitis B surface antigen (HBsAg), you have ...

  20. Hepatitis C and HIV

    MedlinePlus

    ... Problems : Hepatitis C Subscribe Translate Text Size Print Hepatitis C What is Hepatitis? Hepatitis means inflammation of the liver. This condition ... our related pages, Hepatitis A and Hepatitis B . Hepatitis C and HIV About 25% of people living ...

  1. Hepatitis B and HIV

    MedlinePlus

    ... Problems : Hepatitis B Subscribe Translate Text Size Print Hepatitis B What is Hepatitis? Hepatitis means inflammation of the liver. This condition ... our related pages, Hepatitis A and Hepatitis C . Hepatitis B and HIV About 10% of people living ...

  2. Chronic overeating impairs hepatic glucose uptake and disposition.

    PubMed

    Coate, Katie C; Kraft, Guillaume; Shiota, Masakazu; Smith, Marta S; Farmer, Ben; Neal, Doss W; Williams, Phil; Cherrington, Alan D; Moore, Mary Courtney

    2015-05-15

    Dogs consuming a hypercaloric high-fat and -fructose diet (52 and 17% of total energy, respectively) or a diet high in either fructose or fat for 4 wk exhibited blunted net hepatic glucose uptake (NHGU) and glycogen deposition in response to hyperinsulinemia, hyperglycemia, and portal glucose delivery. The effect of a hypercaloric diet containing neither fructose nor excessive fat has not been examined. Dogs with an initial weight of ≈25 kg consumed a chow and meat diet (31% protein, 44% carbohydrate, and 26% fat) in weight-maintaining (CTR; n = 6) or excessive (Hkcal; n = 7) amounts for 4 wk (cumulative weight gain 0.0 ± 0.3 and 1.5 ± 0.5 kg, respectively, P < 0.05). They then underwent clamp studies with infusions of somatostatin and intraportal insulin (4× basal) and glucagon (basal). The hepatic glucose load was doubled with peripheral (Pe) glucose infusion for 90 min (P1) and intraportal glucose at 4 mg·kg(-1)·min(-1) plus Pe glucose for the final 90 min (P2). NHGU was blunted (P < 0.05) in Hkcal during both periods (mg·kg(-1)·min(-1); P1: 1.7 ± 0.2 vs. 0.3 ± 0.4; P2: 3.6 ± 0.3 vs. 2.3 ± 0.4, CTR vs. Hkcal, respectively). Terminal hepatic glucokinase catalytic activity was reduced nearly 50% in Hkcal vs. CTR (P < 0.05), although glucokinase protein did not differ between groups. In Hkcal vs. CTR, liver glycogen was reduced 27% (P < 0.05), with a 91% increase in glycogen phosphorylase activity (P < 0.05) but no significant difference in glycogen synthase activity. Thus, Hkcal impaired NHGU and glycogen synthesis compared with CTR, indicating that excessive energy intake, even if the diet is balanced and nutritious, negatively impacts hepatic glucose metabolism. PMID:25783892

  3. Hepatitis Testing

    MedlinePlus

    ... caused by viruses. They include hepatitis A, hepatitis B, and hepatitis C. To diagnose hepatitis, your health care provider will ask you about your medical history and symptoms, do a physical exam, and order blood tests. There are blood tests for each type of ...

  4. Glucose uptake and glycogen synthesis in muscles from immobilized limbs

    NASA Technical Reports Server (NTRS)

    Nicholson, W. F.; Watson, P. A.; Booth, F. W.

    1984-01-01

    Defects in glucose metabolism in muscles of immobilized limbs of mice were related to alterations in insulin binding, insulin responsiveness, glucose supply, and insulin activation of glycogen synthase. These were tested by in vitro methodology. A significant lessening in the insulin-induced maximal response of 2-deoxyglucose uptake into the mouse soleus muscle occurred between the 3rd and 8th h of limb immobilization, suggesting a decreased insulin responsiveness. Lack of change in the specific binding of insulin to muscles of 24-h immobilized limbs indicates that a change in insulin receptor number did not play a role in the failure of insulin to stimulate glucose metabolism. Its inability to stimulate glycogen synthesis in muscle from immobilized limbs is due, in part, to a lack of glucose supply to glycogen synthesis and also to the ineffectiveness of insulin to increase the percentage of glycogen synthase in its active form in muscles from 24-h immobilized limbs.

  5. Genetics Home Reference: glycogen storage disease type III

    MedlinePlus

    ... blood (hyperlipidemia), and elevated blood levels of liver enzymes. As they get older, children with this condition ... gene provides instructions for making the glycogen debranching enzyme. This enzyme is involved in the breakdown of ...

  6. Human Brain Glycogen Metabolism During and After Hypoglycemia

    PubMed Central

    Öz, Gülin; Kumar, Anjali; Rao, Jyothi P.; Kodl, Christopher T.; Chow, Lisa; Eberly, Lynn E.; Seaquist, Elizabeth R.

    2009-01-01

    OBJECTIVE We tested the hypotheses that human brain glycogen is mobilized during hypoglycemia and its content increases above normal levels (“supercompensates”) after hypoglycemia. RESEARCH DESIGN AND METHODS We utilized in vivo 13C nuclear magnetic resonance spectroscopy in conjunction with intravenous infusions of [13C]glucose in healthy volunteers to measure brain glycogen metabolism during and after euglycemic and hypoglycemic clamps. RESULTS After an overnight intravenous infusion of 99% enriched [1-13C]glucose to prelabel glycogen, the rate of label wash-out from [1-13C]glycogen was higher (0.12 ± 0.05 vs. 0.03 ± 0.06 μmol · g−1 · h−1, means ± SD, P < 0.02, n = 5) during a 2-h hyperinsulinemic-hypoglycemic clamp (glucose concentration 57.2 ± 9.7 mg/dl) than during a hyperinsulinemic-euglycemic clamp (95.3 ± 3.3 mg/dl), indicating mobilization of glucose units from glycogen during moderate hypoglycemia. Five additional healthy volunteers received intravenous 25–50% enriched [1-13C]glucose over 22–54 h after undergoing hyperinsulinemic-euglycemic (glucose concentration 92.4 ± 2.3 mg/dl) and hyperinsulinemic-hypoglycemic (52.9 ± 4.8 mg/dl) clamps separated by at least 1 month. Levels of newly synthesized glycogen measured from 4 to 80 h were higher after hypoglycemia than after euglycemia (P ≤ 0.01 for each subject), indicating increased brain glycogen synthesis after moderate hypoglycemia. CONCLUSIONS These data indicate that brain glycogen supports energy metabolism when glucose supply from the blood is inadequate and that its levels rebound to levels higher than normal after a single episode of moderate hypoglycemia in humans. PMID:19502412

  7. Structure and solution properties of enzymatically synthesized glycogen.

    PubMed

    Kajiura, Hideki; Takata, Hiroki; Kuriki, Takashi; Kitamura, Shinichi

    2010-04-19

    Recently, a new enzymatic process for glycogen production was developed. In this process, short-chain amylose is used as a substrate for branching enzymes (BE, EC 2.4.1.18). The molecular weight of the enzymatically synthesized glycogen (ESG) depends on the size and concentration of the substrate. Structural and physicochemical properties of ESG were compared to those of natural source glycogen (NSG). The average chain length, interior chain length, and exterior chain length of ESG were 8.2-11.6, 2.0-3.3, and 4.2-7.6, respectively. These values were within the range of variation of NSG. The appearances of both ESG and NSG in solution were opalescent (milky white and slightly bluish). Furthermore, transmission electron microscopy and atomic force microscopy showed that ESG molecules formed spherical particles, and that there were no differences between ESG and NSG. Viscometric analyses also showed the spherical nature of both glycogens. When ESG and NSG were treated with pullulanase, a glucan-hydrolyzing enzyme known to degrade glycogen only on its surface portion, both glycogens were similarly degraded. These analyses revealed that ESG shares similar molecular shapes and surface properties with NSG. PMID:20153852

  8. Significant modulation of the hepatic proteome induced by exposure to low temperature in Xenopus laevis

    PubMed Central

    Nagasawa, Kazumichi; Tanizaki, Yuta; Okui, Takehito; Watarai, Atsuko; Ueda, Shinobu; Kato, Takashi

    2013-01-01

    Summary The African clawed frog, Xenopus laevis, is an ectothermic vertebrate that can survive at low environmental temperatures. To gain insight into the molecular events induced by low body temperature, liver proteins were evaluated at the standard laboratory rearing temperature (22°C, control) and a low environmental temperature (5°C, cold exposure). Using nano-flow liquid chromatography coupled with tandem mass spectrometry, we identified 58 proteins that differed in abundance. A subsequent Gene Ontology analysis revealed that the tyrosine and phenylalanine catabolic processes were modulated by cold exposure, which resulted in decreases in hepatic tyrosine and phenylalanine, respectively. Similarly, levels of pyruvate kinase and enolase, which are involved in glycolysis and glycogen synthesis, were also decreased, whereas levels of glycogen phosphorylase, which participates in glycogenolysis, were increased. Therefore, we measured metabolites in the respective pathways and found that levels of hepatic glycogen and glucose were decreased. Although the liver was under oxidative stress because of iron accumulation caused by hepatic erythrocyte destruction, the hepatic NADPH/NADP ratio was not changed. Thus, glycogen is probably utilized mainly for NADPH supply rather than for energy or glucose production. In conclusion, X. laevis responds to low body temperature by modulating its hepatic proteome, which results in altered carbohydrate metabolism. PMID:24167716

  9. Molecular Basis of Impaired Glycogen Metabolism during Ischemic Stroke and Hypoxia

    PubMed Central

    Hossain, Mohammed Iqbal; Roulston, Carli Lorraine; Stapleton, David Ian

    2014-01-01

    Background Ischemic stroke is the combinatorial effect of many pathological processes including the loss of energy supplies, excessive intracellular calcium accumulation, oxidative stress, and inflammatory responses. The brain's ability to maintain energy demand through this process involves metabolism of glycogen, which is critical for release of stored glucose. However, regulation of glycogen metabolism in ischemic stroke remains unknown. In the present study, we investigate the role and regulation of glycogen metabolizing enzymes and their effects on the fate of glycogen during ischemic stroke. Results Ischemic stroke was induced in rats by peri-vascular application of the vasoconstrictor endothelin-1 and forebrains were collected at 1, 3, 6 and 24 hours post-stroke. Glycogen levels and the expression and activity of enzymes involved in glycogen metabolism were analyzed. We found elevated glycogen levels in the ipsilateral hemispheres compared with contralateral hemispheres at 6 and 24 hours (25% and 39% increase respectively; P<0.05). Glycogen synthase activity and glycogen branching enzyme expression were found to be similar between the ipsilateral, contralateral, and sham control hemispheres. In contrast, the rate-limiting enzyme for glycogen breakdown, glycogen phosphorylase, had 58% lower activity (P<0.01) in the ipsilateral hemisphere (24 hours post-stroke), which corresponded with a 48% reduction in cAMP-dependent protein kinase A (PKA) activity (P<0.01). In addition, glycogen debranching enzyme expression 24 hours post-stroke was 77% (P<0.01) and 72% lower (P<0.01) at the protein and mRNA level, respectively. In cultured rat primary cerebellar astrocytes, hypoxia and inhibition of PKA activity significantly reduced glycogen phosphorylase activity and increased glycogen accumulation but did not alter glycogen synthase activity. Furthermore, elevated glycogen levels provided metabolic support to astrocytes during hypoxia. Conclusion Our study has

  10. Potential Contribution of Cytochrome P450 2B6 to Hepatic 4-Hydroxycyclophosphamide Formation In Vitro and In VivoS⃞

    PubMed Central

    Raccor, Brianne S.; Claessens, Adam J.; Dinh, Jean C.; Park, Julie R.; Hawkins, Douglas S.; Thomas, Sushma S.; Makar, Karen W.; McCune, Jeannine S.

    2012-01-01

    Results from retrospective studies on the relationship between cytochrome P450 (P450) 2B6 (CYP2B6) genotype and cyclophosphamide (CY) efficacy and toxicity in adult cancer patients have been conflicting. We evaluated this relationship in children, who have faster CY clearance and receive different CY-based regimens than adults. These factors may influence the P450s metabolizing CY to 4-hydroxycyclophosphamide (4HCY), the principal precursor to CY's cytotoxic metabolite. Therefore, we sought to characterize the in vitro and in vivo roles of hepatic CYP2B6 and its main allelic variants in 4HCY formation. CYP2B6 is the major isozyme responsible for 4HCY formation in recombinant P450 Supersomes. In human liver microsomes (HLM), 4HCY formation correlated with known phenotypic markers of CYP2B6 activity, specifically formation of (S)-2-ethyl-1,5-dimethyl-3,3-diphenyl pyrrolidine and hydroxybupropion. However, in HLM, CYP3A4/5 also contributes to 4HCY formation at the CY concentrations similar to plasma concentrations achieved in children (0.1 mM). 4HCY formation was not associated with CYP2B6 genotype at low (0.1 mM) or high (1 mM) CY concentrations potentially because CYP3A4/5 and other isozymes also form 4HCY. To remove this confounder, 4HCY formation was evaluated in recombinant CYP2B6 enzymes, which demonstrated that 4HCY formation was lower for CYP2B6.4 and CYP2B6.5 compared with CYP2B6.1. In vivo, CYP2B6 genotype was not directly related to CY clearance or ratio of 4HCY/CY areas under the curve in 51 children receiving CY-based regimens. Concomitant chemotherapy agents did not influence 4HCY formation in vitro. We conclude that CYP2B6 genotype is not consistently related to 4HCY formation in vitro or in vivo. PMID:21976622

  11. Loss of the starvation-induced gene Rack1 leads to glycogen deficiency and impaired autophagic responses in Drosophila

    PubMed Central

    Érdi, Balázs; Nagy, Péter; Zvara, Ágnes; Varga, Ágnes; Pircs, Karolina; Ménesi, Dalma; Puskás, László G.; Juhász, Gábor

    2012-01-01

    Autophagy delivers cytoplasmic material for lysosomal degradation in eukaryotic cells. Starvation induces high levels of autophagy to promote survival in the lack of nutrients. We compared genome-wide transcriptional profiles of fed and starved control, autophagy-deficient Atg7 and Atg1 null mutant Drosophila larvae to search for novel regulators of autophagy. Genes involved in catabolic processes including autophagy were transcriptionally upregulated in all cases. We also detected repression of genes involved in DNA replication in autophagy mutants compared with control animals. The expression of Rack1 (receptor of activated protein kinase C 1) increased 4.1- to 5.5-fold during nutrient deprivation in all three genotypes. The scaffold protein Rack1 plays a role in a wide range of processes including translation, cell adhesion and migration, cell survival and cancer. Loss of Rack1 led to attenuated autophagic response to starvation, and glycogen stores were decreased 11.8-fold in Rack1 mutant cells. Endogenous Rack1 partially colocalized with GFP-Atg8a and early autophagic structures on the ultrastructural level, suggesting its involvement in autophagosome formation. Endogenous Rack1 also showed a high degree of colocalization with glycogen particles in the larval fat body, and with Shaggy, the Drosophila homolog of glycogen synthase kinase 3B (GSK-3B). Our results, for the first time, demonstrated the fundamental role of Rack1 in autophagy and glycogen synthesis. PMID:22562043

  12. Neurons have an active glycogen metabolism that contributes to tolerance to hypoxia

    PubMed Central

    Saez, Isabel; Duran, Jordi; Sinadinos, Christopher; Beltran, Antoni; Yanes, Oscar; Tevy, María F; Martínez-Pons, Carlos; Milán, Marco; Guinovart, Joan J

    2014-01-01

    Glycogen is present in the brain, where it has been found mainly in glial cells but not in neurons. Therefore, all physiologic roles of brain glycogen have been attributed exclusively to astrocytic glycogen. Working with primary cultured neurons, as well as with genetically modified mice and flies, here we report that—against general belief—neurons contain a low but measurable amount of glycogen. Moreover, we also show that these cells express the brain isoform of glycogen phosphorylase, allowing glycogen to be fully metabolized. Most importantly, we show an active neuronal glycogen metabolism that protects cultured neurons from hypoxia-induced death and flies from hypoxia-induced stupor. Our findings change the current view of the role of glycogen in the brain and reveal that endogenous neuronal glycogen metabolism participates in the neuronal tolerance to hypoxic stress. PMID:24569689

  13. In vitro differentiation of unrestricted somatic stem cells into functional hepatic-like cells displaying a hepatocyte-like glucose metabolism.

    PubMed

    Waclawczyk, Simon; Buchheiser, Anja; Flögel, Ulrich; Radke, Teja F; Kögler, Gesine

    2010-11-01

    The hepatic-like phenotype resulting from in vitro differentiation of unrestricted somatic stem cells (USSC) derived from human umbilical cord blood (CB) was analyzed with regard to functional and metabolic aspects. USSC can be differentiated into cells of all three germ layers in vitro and in vivo and, although they share many features with mesenchymal stroma cells (MSC), can be distinguished from these by their expression of DLK1 as well as a restricted adipogenic differentiation potential. For the differentiation procedure described herein, a novel three-stage differentiation protocol resembling embryonic developmental processes of hepatic endoderm was applied. Hepatic pre-induction was performed by activinA and FGF4 resulting in enhanced SOX17 and FOXA2 expression. Further differentiation was achieved sequentially by retinoic acid, FGF4, HGF, EGF, and OSM resulting in a hepatic endodermal identity, characterized by the expression of AFP and HNF1alpha. Thereafter, expression of G6PC, ARG1, FBP1, and HNF4alpha was observed, thus indicating progressive differentiation. Functional studies concerning albumin secretion, urea formation, and cytochrome-p450-3A4 (CYP3A4) enzyme activity confirmed the hepatic-like phenotype. In order to characterize the differentiated cells at a metabolic level, USSC were incubated with [1-(13)C]glucose. By tracing the fate of the molecule's label via isotopomer analysis using (13)C NMR spectroscopy, formation of both glycogen and some gluconeogenetic activity could be observed providing evidence of a hepatocyte-like glucose metabolism in differentiated USSC. In conclusion, the results of the present study indicate that USSC represent a stem cell source with a substantial hepatic differentiation capacity which hold the potential for clinical applications. PMID:20458755

  14. Lithium Induces Glycogen Accumulation in Salivary Glands of the Rat.

    PubMed

    Souza, D N; Mendes, F M; Nogueira, F N; Simões, A; Nicolau, J

    2016-02-01

    Lithium is administered for the treatment of mood and bipolar disorder. The aim of this study was to verify whether treatment with different concentrations of lithium may affect the glycogen metabolism in the salivary glands of the rats when compared with the liver. Mobilization of glycogen in salivary glands is important for the process of secretion. Two sets of experiments were carried out, that is, in the first, the rats received drinking water supplemented with LiCl (38,25 and 12 mM of LiCl for 15 days) and the second experiment was carried out by intraperitoneal injection of LiCl solution (12 mg/kg and 45 mg LiCl/kg body weight) for 3 days. The active form of glycogen phosphorylase was not affected by treatment with LiCl considering the two experiments. The active form of glycogen synthase presented higher activity in the submandibular glands of rats treated with 25 and 38 mM LiCl and in the liver, with 25 mM LiCl. Glycogen level was higher than that of control in the submandibular glands of rats receiving 38 and 12 mM LiCl, in the parotid of rats receiving 25 and 38 mM, and in the liver of rats receiving 12 mM LiCl. The absolute value of glycogen for the submandibular treated with 25 mM LiCl, and the liver treated with 38 mM LiCl, was higher than the control value, although not statistically significant for these tissues. No statistically significant difference was found in the submandibular and parotid salivary glands for protein concentration when comparing experimental and control groups. We concluded that LiCl administered to rats influences the metabolism of glycogen in salivary glands. PMID:26155966

  15. Digestion of glycogen by a glucosidase released by Trichomonas vaginalis.

    PubMed

    Huffman, Ryan D; Nawrocki, Lauren D; Wilson, Wayne A; Brittingham, Andrew

    2015-12-01

    Trichomonas vaginalis is a protozoan parasite that is the causative agent of trichomoniasis, a widespread sexually transmitted disease. In vitro culture of T. vaginalis typically employs a medium supplemented with either maltose or glucose and carbohydrates are considered essential for growth. Although the nature of the carbohydrates utilized by T. vaginalis in vivo is undefined, the vaginal epithelium is rich in glycogen, which appears to provide a source of carbon for the vaginal microbiota. Here, we show that T. vaginalis grows equally well in growth media supplemented with simple sugars or with glycogen. Analysis of conditioned growth medium by thin layer chromatography indicates that growth on glycogen is accompanied by glycogen breakdown to a mixture of products including maltose, glucose, and oligosaccharides. Enzymatic assays with conditioned growth medium show that glycogen breakdown is accomplished via the release of a glucosidase activity having the properties of an α-amylase into the growth medium. Furthermore, we find that released glucosidase activity increases upon removal of carbohydrate from the growth medium, indicating regulation of synthesis and/or secretion in response to environmental cues. Lastly, we show that addition of T. vaginalis glucosidase activity to a growth medium containing glycogen generates sufficient simple sugar to support the growth of lactobacilli which, themselves, are unable to degrade glycogen. Thus, not only does the glucosidase activity likely play an important role in allowing T. vaginalis to secure simple sugars for its own use, it has the potential to impact the growth of other members of the vaginal microbiome. PMID:26420465

  16. Hepatitis B and Hepatitis C in Pregnancy

    MedlinePlus

    ... infected with the hepatitis B virus, can I breastfeed? • If I am infected with the hepatitis B ... infected with the hepatitis C virus, can I breastfeed? • Glossary What are hepatitis B and hepatitis C ...

  17. Time-dependent effect of ethanol force-feeding on glycogen repletion: NMR evidence of a link with ATP turnover in rat liver.

    PubMed

    Beauvieux, Marie-Christine; Gin, Henri; Roumes, Hélène; Kassem, Cendrella; Couzigou, Patrice; Gallis, Jean-Louis

    2015-09-01

    The purpose was to study the hepatic effects of low-dose ethanol on the links between ATP and glycogen production. Fasted male Wistar rats received a single force-feeding of glucose plus ethanol or isocaloric glucose. At different times after force-feeding (0-10 h), glycogen repletion and ATP characteristics (content, apparent catalytic time constant, mitochondrial turnover) were monitored by (13)C- or (31)P-nuclear magnetic resonance (NMR) in perfused and isolated liver. In vivo glycogen repletion after force-feeding was slower after glucose plus ethanol vs. glucose (12.04 ± 0.68 and 8.50 ± 0.86 μmol/h/g liver wet weight [ww], respectively), reaching a maximum at the 6th hour. From the 3rd to the 8th hour, glycogen content was lower after glucose plus ethanol vs. glucose. After glucose plus ethanol, the correlation between glycogen and ATP contents presented two linear steps: before and after the 3rd hour (30 and 102 μmol glycogen/g ww per μmol ATP/g ww, respectively, the latter being near the single step measured in glucose). After glucose plus ethanol, ATP turnover remained stable for 2 h, was 3-fold higher from the 3rd hour to the 8th hour, and was higher than after glucose (2.59 ± 0.45 and 1.39 ± 0.19 μmol/min/g ww, respectively). In the 1st hour, glucose plus ethanol induced a transient acidosis and an increase in the phosphomonoesters signal. In conclusion, after ethanol consumption, a large part of the ATP production was diverted to redox re-equilibrium during the first 2 h, thereby reducing the glycogen synthesis. Thereafter, the maintenance of a large oxidative phosphorylation allowed the stimulation of glycogen synthesis requiring ATP. PMID:26254966

  18. X-ray microanalysis of aldehyde-fixed glycogen contrast-stained by OsVI . FeII and OsVI . RuIV complexes.

    PubMed

    de Bruijn, W C; van Buitenen, J M

    1980-11-01

    The composition of the contrast-donating complex of rat liver glycogen, nucleoplasm, erythrocytes, and mitochondria was established by X-ray microanalysis. In these compartments the presence of osmium and iron was shown qualitatively in tissue after glutaraldehyde fixation, treated with OsVIIIO4 plus K4FeII(CN)6 and in similar tissue treated with a combination of K2OsVIO4 plus K4FeII(CN)6. Osmium and ruthenium were detected in these compartments, in aldehyde-fixed tissue treated with mixtures containing K2RuIVL(CN)6 rather than K4FeII(CN)6. The iron detected in the glycogen, nucleoplasm, erythrocytes, and mitochondria of tissue treated with K2RuIV(CN)6 mixtures proved to derive from sources inside the electron microscope, and had to be considered an artifact. Quantitatively, the mean atomic ratios of osmium-to-iron and osmium-to-ruthenium were determined from spectra obtained by point analyses of the same compartments (glycogen, nucleoplasm, mitochondria, lipid droplets, and erythrocytes). After correction of the spectra for the instrumental iron contribution, the osmium-to-iron and osmium-to-ruthenium ratios in the glycogen were about 1:3 for tissue treated with those combinations including K2OsVIO4. In the other compartments, the osmium-to-iron and osmium-to-ruthenium ratios were virtually 1:0. For Os-VIIIO4 in combination with potassium ferrouscyanide however the osmium-to-iron ratio was 1:7 in the glycogen and 1:5 in all other compartments. OsVIIIO4 was combined with potassium ruthenium-cyanide, the osmium-to-ruthenium ratio was 1:2 in the glycogen and 2:1 in the other compartments. These results support our view that the selective glycogen contrast is obtained by complex formation. PMID:6159393

  19. Hepatitis virus panel

    MedlinePlus

    Hepatitis A antibody test; Hepatitis B antibody test; Hepatitis C antibody test; Hepatitis D antibody test ... There are different tests for hepatitis A and B. A positive test is ... may mean: You currently have a hepatitis infection. This may ...

  20. Hepatitis C: Treatment

    MedlinePlus

    ... Public Home » Hepatitis C » Hepatitis C Treatment Viral Hepatitis Menu Menu Viral Hepatitis Viral Hepatitis Home For ... Enter ZIP code here Enter ZIP code here Hepatitis C Treatment for Veterans and the Public Treatment ...

  1. Hepatitis C and Incarceration

    MedlinePlus

    HEPATITIS C & INCARCERATION What is hepatitis? “Hepatitis” means inflammation or swelling of the liver. The liver is an important ... viral hepatitis: Hepatitis A, Hepatitis B, and Hepatitis C. They are all different from each other and ...

  2. Hepatic Encephalopathy

    MedlinePlus Videos and Cool Tools

    ... is Hepatic Encephalopathy? Hepatic Encephalopathy, sometimes referred to as portosystemic encephalopathy or PSE, is a condition that ... medical care is an important factor in staying as healthy as possible. The American Liver Foundation is ...

  3. Hepatitis D

    MedlinePlus

    ... if the hepatitis B virus is also present. Transmission Hepatitis D can be found in the blood, ... other body fluids of people who are infected. Transmission happens when infected body fluid enters another person’s ...

  4. Autoimmune hepatitis

    MedlinePlus

    Lupoid hepatitis; Chronic acute liver disease ... This form of hepatitis is an autoimmune disease . The body's immune system cannot tell the difference between healthy body tissue and harmful, outside ...

  5. Hepatic ischemia

    MedlinePlus

    Hepatic ischemia is a condition in which the liver does not get enough blood or oxygen, causing injury to ... pressure from any condition can lead to hepatic ischemia. Such conditions may include: Abnormal heart rhythms Dehydration ...

  6. Hepatitis A

    MedlinePlus

    ... an inflammation of the liver. One type, hepatitis A, is caused by the hepatitis A virus (HAV). The disease spreads through contact with ... washed in untreated water Putting into your mouth a finger or object that came into contact with ...

  7. Hepatitis B

    MedlinePlus

    ... this page: //medlineplus.gov/ency/article/000279.htm Hepatitis B To use the sharing features on this page, please enable JavaScript. Hepatitis B is irritation and swelling (inflammation) of the ...

  8. Hepatitis C

    MedlinePlus

    ... 2014 Select a Language: Fact Sheet 507 Hepatitis C WHAT IS HEPATITIS C? HOW IS IT DIAGNOSED? ... treatment may be less likely to work. Hep C treatment is less effective for coinfected people. Cure ...

  9. A new non-degradative method to purify glycogen.

    PubMed

    Tan, Xinle; Sullivan, Mitchell A; Gao, Fei; Li, Shihan; Schulz, Benjamin L; Gilbert, Robert G

    2016-08-20

    Liver glycogen, a complex branched glucose polymer containing a small amount of protein, is important for maintaining glucose homeostasis (blood-sugar control) in humans. It has recently been found that glycogen molecular structure is impaired in diabetes. Isolating the carbohydrate polymer and any intrinsically-attached protein(s) is an essential prerequisite for studying this structural impairment. This requires an effective, non-degradative and efficient purification method to exclude the many other proteins present in liver. Proteins and glycogen have different ranges of molecular sizes. Despite the plethora of proteins that might still be present in significant abundance after other isolation techniques, SEC (size exclusion chromatography, also known as GPC), which separates by molecular size, should separate those extraneous to glycogen from glycogen with any intrinsically associated protein(s). A novel purification method is developed for this, based on preparative SEC following sucrose gradient centrifugation. Proteomics is used to show that the new method compares favourably with current methods in the literature. PMID:27178921

  10. Molecular dynamics simulation of paracetamol molecules ordering around glycogen

    NASA Astrophysics Data System (ADS)

    Lim, Wilber; Feng, Yuan Ping; Liu, X. Y.

    2005-05-01

    By the use of classical atomistic molecular dynamics simulations, we demonstrate that paracetamol molecules exist in a highly ordered phase in the presence of a glycogen substrate at 317K whereas the paracetamol fluid exists in an isotropic phase in the absence of the glycogen substrate at the same temperature. This result further validates the studies made on polysaccharide regarding its abilities to promote nucleation of paracetamol via liquid preordering. As little is known regarding liquid ordering induced by a polymeric substrate, we seek to explore the ordering mechanism from an energy perspective. This is accomplished using conformation mappings. Our analysis shows that the conformation space accessible to the paracetamol molecule at 317K in the vicinity of glycogen is smaller than the one in the absence of glycogen. An investigation on the orientation of the dipole moments of the glycogen monomers and paracetamol molecules were carried out as well. From the investigations, we show that dipolar interactions play an important role in the ordering process. These studies bear significance to the understanding of the ordering process as well as the promotion and effective control of the nucleation rate.

  11. Chronic central leptin infusion modulates the glycemia response to insulin administration in male rats through regulation of hepatic glucose metabolism.

    PubMed

    Burgos-Ramos, Emma; Canelles, Sandra; Rodríguez, Amaia; Gómez-Ambrosi, Javier; Frago, Laura M; Chowen, Julie A; Frühbeck, Gema; Argente, Jesús; Barrios, Vicente

    2015-11-01

    Leptin and insulin use overlapping signaling mechanisms to modify hepatic glucose metabolism, which is critical in maintaining normal glycemia. We examined the effect of an increase in central leptin and insulin on hepatic glucose metabolism and its influence on serum glucose levels. Chronic leptin infusion increased serum leptin and reduced hepatic SH-phosphotyrosine phosphatase 1, the association of suppressor of cytokine signaling 3 to the insulin receptor in liver and the rise in glycemia induced by central insulin. Leptin also decreased hepatic phosphoenolpyruvate carboxykinase levels and increased insulin's ability to phosphorylate insulin receptor substrate-1, Akt and glycogen synthase kinase on Ser9 and to stimulate glucose transporter 2 and glycogen levels. Peripheral leptin treatment reproduced some of these changes, but to a lesser extent. Our data indicate that leptin increases the hepatic response to a rise in insulin, suggesting that pharmacological manipulation of leptin targets may be of interest for controlling glycemia. PMID:26296906

  12. A functional glycogen biosynthesis pathway in Lactobacillus acidophilus: expression and analysis of the glg operon

    PubMed Central

    Goh, Yong Jun; Klaenhammer, Todd R

    2013-01-01

    Glycogen metabolism contributes to energy storage and various physiological functions in some prokaryotes, including colonization persistence. A role for glycogen metabolism is proposed on the survival and fitness of Lactobacillus acidophilus, a probiotic microbe, in the human gastrointestinal environment. L. acidophilus NCFM possesses a glycogen metabolism (glg) operon consisting of glgBCDAP-amy-pgm genes. Expression of the glg operon and glycogen accumulation were carbon source- and growth phase-dependent, and were repressed by glucose. The highest intracellular glycogen content was observed in early log-phase cells grown on trehalose, which was followed by a drastic decrease of glycogen content prior to entering stationary phase. In raffinose-grown cells, however, glycogen accumulation gradually declined following early log phase and was maintained at stable levels throughout stationary phase. Raffinose also induced an overall higher temporal glg expression throughout growth compared with trehalose. Isogenic ΔglgA (glycogen synthase) and ΔglgB (glycogen-branching enzyme) mutants are glycogen-deficient and exhibited growth defects on raffinose. The latter observation suggests a reciprocal relationship between glycogen synthesis and raffinose metabolism. Deletion of glgB or glgP (glycogen phosphorylase) resulted in defective growth and increased bile sensitivity. The data indicate that glycogen metabolism is involved in growth maintenance, bile tolerance and complex carbohydrate utilization in L. acidophilus. PMID:23879596

  13. Glycogen supercompensation in rat soleus muscle during recovery from nonweight bearing.

    PubMed

    Henriksen, E J; Kirby, C R; Tischler, M E

    1989-06-01

    The time course of glycogen changes in soleus muscle recovering from 3 days of nonweight bearing by hindlimb suspension was investigated. Within 15 min and up to 2 h, muscle glycogen decreased. Coincidentally, muscle glucose 6-phosphate and the fractional activity of glycogen phosphorylase, measured at the fresh muscle concentrations of AMP, increased. Increased fractional activity of glycogen synthase during this time was likely the result of greater glucose 6-phosphate and decreased glycogen. From 2 to 4 h, when the synthase activity remained elevated and the phosphorylase activity declined, glycogen levels increased (glycogen supercompensation). A further increase of glycogen up to 24 h did not correlate with the enzyme activities. Between 24 and 72 h, glycogen decreased to control values, possibly initiated by high phosphorylase activity at 24 h. At 12 and 24 h, the inverse relationship between glycogen concentration and the synthase activity ratio was lost, indicating that reloading transiently uncoupled glycogen control of this enzyme. These data suggest that the activities of glycogen synthase and phosphorylase, when measured at physiological effector levels, likely provide the closest approximation to the actual enzyme activities in vivo. Measurements made in this way effectively explained the majority of the changes in the soleus glycogen content during recovery from nonweight bearing. PMID:2501291

  14. A functional glycogen biosynthesis pathway in Lactobacillus acidophilus: expression and analysis of the glg operon.

    PubMed

    Goh, Yong Jun; Klaenhammer, Todd R

    2013-09-01

    Glycogen metabolism contributes to energy storage and various physiological functions in some prokaryotes, including colonization persistence. A role for glycogen metabolism is proposed on the survival and fitness of Lactobacillus acidophilus, a probiotic microbe, in the human gastrointestinal environment. L. acidophilus NCFM possesses a glycogen metabolism (glg) operon consisting of glgBCDAP-amy-pgm genes. Expression of the glg operon and glycogen accumulation were carbon source- and growth phase-dependent, and were repressed by glucose. The highest intracellular glycogen content was observed in early log-phase cells grown on trehalose, which was followed by a drastic decrease of glycogen content prior to entering stationary phase. In raffinose-grown cells, however, glycogen accumulation gradually declined following early log phase and was maintained at stable levels throughout stationary phase. Raffinose also induced an overall higher temporal glg expression throughout growth compared with trehalose. Isogenic ΔglgA (glycogen synthase) and ΔglgB (glycogen-branching enzyme) mutants are glycogen-deficient and exhibited growth defects on raffinose. The latter observation suggests a reciprocal relationship between glycogen synthesis and raffinose metabolism. Deletion of glgB or glgP (glycogen phosphorylase) resulted in defective growth and increased bile sensitivity. The data indicate that glycogen metabolism is involved in growth maintenance, bile tolerance and complex carbohydrate utilization in L. acidophilus. PMID:23879596

  15. Hepatitis A

    MedlinePlus

    ... is an inflammation of the liver. One type, hepatitis A, is caused by the hepatitis A virus (HAV). The disease spreads through contact with ... suggest medicines to help relieve your symptoms. The hepatitis A vaccine can prevent HAV. Good hygiene can also ...

  16. Hepatitis A

    MedlinePlus

    ... Organizations ​​ (PDF, 341 KB)​​​​​ Alternate Language URL Español Hepatitis A Page Content On this page: What is ... Nutrition Points to Remember Clinical Trials What is hepatitis A? Hepatitis * A is a virus , or infection, ...

  17. Autoimmune Hepatitis

    MedlinePlus

    ... Organizations ​​ (PDF, 341 KB)​​​​​ Alternate Language URL Autoimmune Hepatitis Page Content On this page: What is autoimmune ... Points to Remember Clinical Trials What is autoimmune hepatitis? Autoimmune hepatitis is a chronic—or long lasting— ...

  18. Hepatitis C

    MedlinePlus

    ... an inflammation of the liver. One type, hepatitis C, is caused by the hepatitis C virus (HCV). It usually spreads through contact with ... childbirth. Most people who are infected with hepatitis C don't have any symptoms for years. If ...

  19. Structural basis of AMPK regulation by adenine nucleotides and glycogen

    SciTech Connect

    Li, Xiaodan; Wang, Lili; Zhou, X. Edward; Ke, Jiyuan; de Waal, Parker W.; Gu, Xin; Tan, M. H. Eileen; Wang, Dongye; Wu, Donghai; Xu, H. Eric; Melcher, Karsten

    2014-11-21

    AMP-activated protein kinase (AMPK) is a central cellular energy sensor and regulator of energy homeostasis, and a promising drug target for the treatment of diabetes, obesity, and cancer. Here we present low-resolution crystal structures of the human α1β2γ1 holo-AMPK complex bound to its allosteric modulators AMP and the glycogen-mimic cyclodextrin, both in the phosphorylated (4.05 Å) and non-phosphorylated (4.60 Å) state. In addition, we have solved a 2.95 Å structure of the human kinase domain (KD) bound to the adjacent autoinhibitory domain (AID) and have performed extensive biochemical and mutational studies. Altogether, these studies illustrate an underlying mechanism of allosteric AMPK modulation by AMP and glycogen, whose binding changes the equilibria between alternate AID (AMP) and carbohydrate-binding module (glycogen) interactions.

  20. Modified glycogen as construction material for functional biomimetic microfibers.

    PubMed

    Rabyk, Mariia; Hruby, Martin; Vetrik, Miroslav; Kucka, Jan; Proks, Vladimir; Parizek, Martin; Konefal, Rafal; Krist, Pavel; Chvatil, David; Bacakova, Lucie; Slouf, Miroslav; Stepanek, Petr

    2016-11-01

    We describe a conceptually new, microfibrous, biodegradable functional material prepared from a modified storage polysaccharide also present in humans (glycogen) showing strong potential as direct-contact dressing/interface material for wound healing. Double bonds were introduced into glycogen via allylation and were further exploited for crosslinking of the microfibers. Triple bonds were introduced by propargylation and served for further click functionalization of the microfibers with bioactive peptide. A simple solvent-free method allowing the preparation of thick layers was used to produce microfibers (diameter ca 2μm) from allylated and/or propargylated glycogen. Crosslinking of the samples was performed by microtron beta-irradiation, and the irradiation dose was optimized to 2kGy. The results from biological testing showed that these highly porous, hydrophilic, readily functionalizable materials were completely nontoxic to cells growing in their presence. The fibers were gradually degraded in the presence of cells. PMID:27516273

  1. Structural basis of AMPK regulation by adenine nucleotides and glycogen

    DOE PAGESBeta

    Li, Xiaodan; Wang, Lili; Zhou, X. Edward; Ke, Jiyuan; de Waal, Parker W.; Gu, Xin; Tan, M. H. Eileen; Wang, Dongye; Wu, Donghai; Xu, H. Eric; et al

    2014-11-21

    AMP-activated protein kinase (AMPK) is a central cellular energy sensor and regulator of energy homeostasis, and a promising drug target for the treatment of diabetes, obesity, and cancer. Here we present low-resolution crystal structures of the human α1β2γ1 holo-AMPK complex bound to its allosteric modulators AMP and the glycogen-mimic cyclodextrin, both in the phosphorylated (4.05 Å) and non-phosphorylated (4.60 Å) state. In addition, we have solved a 2.95 Å structure of the human kinase domain (KD) bound to the adjacent autoinhibitory domain (AID) and have performed extensive biochemical and mutational studies. Altogether, these studies illustrate an underlying mechanism of allostericmore » AMPK modulation by AMP and glycogen, whose binding changes the equilibria between alternate AID (AMP) and carbohydrate-binding module (glycogen) interactions.« less

  2. Structural basis of AMPK regulation by adenine nucleotides and glycogen

    PubMed Central

    Li, Xiaodan; Wang, Lili; Zhou, X Edward; Ke, Jiyuan; de Waal, Parker W; Gu, Xin; Tan, M H Eileen; Wang, Dongye; Wu, Donghai; Xu, H Eric; Melcher, Karsten

    2015-01-01

    AMP-activated protein kinase (AMPK) is a central cellular energy sensor and regulator of energy homeostasis, and a promising drug target for the treatment of diabetes, obesity, and cancer. Here we present low-resolution crystal structures of the human α1β2γ1 holo-AMPK complex bound to its allosteric modulators AMP and the glycogen-mimic cyclodextrin, both in the phosphorylated (4.05 Å) and non-phosphorylated (4.60 Å) state. In addition, we have solved a 2.95 Å structure of the human kinase domain (KD) bound to the adjacent autoinhibitory domain (AID) and have performed extensive biochemical and mutational studies. Together, these studies illustrate an underlying mechanism of allosteric AMPK modulation by AMP and glycogen, whose binding changes the equilibria between alternate AID (AMP) and carbohydrate-binding module (glycogen) interactions. PMID:25412657

  3. Role in Tumor Growth of a Glycogen Debranching Enzyme Lost in Glycogen Storage Disease

    PubMed Central

    Guin, Sunny; Pollard, Courtney; Ru, Yuanbin; Ritterson Lew, Carolyn; Duex, Jason E.; Dancik, Garrett; Owens, Charles; Spencer, Andrea; Knight, Scott; Holemon, Heather; Gupta, Sounak; Hansel, Donna; Hellerstein, Marc; Lorkiewicz, Pawel; Lane, Andrew N.; Fan, Teresa W.-M.

    2014-01-01

    Background Bladder cancer is the most common malignancy of the urinary system, yet our molecular understanding of this disease is incomplete, hampering therapeutic advances. Methods Here we used a genome-wide functional short-hairpin RNA (shRNA) screen to identify suppressors of in vivo bladder tumor xenograft growth (n = 50) using bladder cancer UMUC3 cells. Next-generation sequencing was used to identify the most frequently occurring shRNAs in tumors. Genes so identified were studied in 561 patients with bladder cancer for their association with stratification of clinical outcome by Kaplan-Meier analysis. The best prognostic marker was studied to determine its mechanism in tumor suppression using anchorage-dependent and -independent growth, xenograft (n = 20), and metabolomic assays. Statistical significance was determined using two-sided Student t test and repeated-measures statistical analysis. Results We identified the glycogen debranching enzyme AGL as a prognostic indicator of patient survival (P = .04) and as a novel regulator of bladder cancer anchorage-dependent (P < .001), anchorage-independent (mean ± standard deviation, 180 ± 23.1 colonies vs 20±9.5 in control, P < .001), and xenograft growth (P < .001). Rescue experiments using catalytically dead AGL variants revealed that this effect is independent of AGL enzymatic functions. We demonstrated that reduced AGL enhances tumor growth by increasing glycine synthesis through increased expression of serine hydroxymethyltransferase 2. Conclusions Using an in vivo RNA interference screen, we discovered that AGL, a glycogen debranching enzyme, has a biologically and statistically significant role in suppressing human cancer growth. PMID:24700805

  4. The influence of social status on hepatic glucose metabolism in rainbow trout Oncorhynchus mykiss.

    PubMed

    Gilmour, Kathleen M; Kirkpatrick, Sheryn; Massarsky, Andrey; Pearce, Brenda; Saliba, Sarah; Stephany, Céleste-Élise; Moon, Thomas W

    2012-01-01

    The effects of chronic social stress on hepatic glycogen metabolism were examined in rainbow trout Oncorhynchus mykiss by comparing hepatocyte glucose production, liver glycogen phosphorylase (GP) activity, and liver β-adrenergic receptors in dominant, subordinate, control, fasted, and cortisol-treated fish. Hepatocyte glucose production in subordinate fish was approximately half that of dominant fish, reflecting hepatocyte glycogen stores in subordinate trout that were just 16% of those in dominant fish. Fasting and/or chronic elevation of cortisol likely contributed to these differences based on similarities among subordinate, fasted, and cortisol-treated fish. However, calculation of the "glycogen gap"--the difference between glycogen stores used and glucose produced--suggested an enhanced gluconeogenic potential in subordinate fish that was not present in fasted or cortisol-treated trout. Subordinate, fasted, and cortisol-treated trout also exhibited similar GP activities (both total activity and that of the active or a form), and these activities were in all cases significantly lower than those in control trout, perhaps reflecting an attempt to protect liver glycogen stores or a modified capacity to activate GP. Dominant trout exhibited the lowest GP activities (20%-24% of the values in control trout). Low GP activities, presumably in conjunction with incoming energy from feeding, allowed dominant fish to achieve the highest liver glycogen concentrations (double the value in control trout). Liver membrane β-adrenoceptor numbers (assessed as the number of (3)H-CGP binding sites) were significantly lower in subordinate than in dominant trout, although this difference did not translate into attenuated adrenergic responsiveness in hepatocyte glucose production in vitro. Transcriptional regulation, likely as a result of fasting, was indicated by significantly lower β(2)-adrenoceptor relative mRNA levels in subordinate and fasted trout. Collectively, the data

  5. Enhanced Symbiotic Performance by Rhizobium tropici Glycogen Synthase Mutants

    PubMed Central

    Marroquí, Silvia; Zorreguieta, Angeles; Santamaría, Carmen; Temprano, Francisco; Soberón, Mario; Megías, Manuel; Downie, J. Allan

    2001-01-01

    We isolated a Tn5-induced Rhizobium tropici mutant that has enhanced capacity to oxidize N,N-dimethyl-p-phenylendiamine (DMPD) and therefore has enhanced respiration via cytochrome oxidase. The mutant had increased levels of the cytochromes c1 and CycM and a small increase in the amount of cytochrome aa3. In plant tests, the mutant increased the dry weight of Phaseolus vulgaris plants by 20 to 38% compared with the control strain, thus showing significantly enhanced symbiotic performance. The predicted product of the mutated gene is homologous to glycogen synthases from several bacteria, and the mutant lacked glycogen. The DNA sequence of the adjacent gene region revealed six genes predicted to encode products homologous to the following gene products from Escherichia coli: glycogen phosphorylase (glgP), glycogen branching enzyme (glgB), ADP glucose pyrophosphorylase (glgC), glycogen synthase (glgA), phosphoglucomutase (pgm), and glycogen debranching enzyme (glgX). All six genes are transcribed in the same direction, and analysis with lacZ gene fusions suggests that the first five genes are organized in one operon, although pgm appears to have an additional promoter; glgX is transcribed independently. Surprisingly, the glgA mutant had decreased levels of high-molecular-weight exopolysaccharide after growth on glucose, but levels were normal after growth on galactose. A deletion mutant was constructed in order to generate a nonpolar mutation in glgA. This mutant had a phenotype similar to that of the Tn5 mutant, indicating that the enhanced respiration and symbiotic nitrogen fixation and decreased exopolysaccharide were due to mutation of glgA and not to a polar effect on a downstream gene. PMID:11208782

  6. Structural Mechanism of Laforin Function in Glycogen Dephosphorylation and Lafora Disease

    PubMed Central

    Raththagala, Madushi; Brewer, M. Kathryn; Parker, Matthew W.; Sherwood, Amanda R.; Wong, Brian K.; Hsu, Simon; Bridges, Travis M.; Paasch, Bradley C.; Hellman, Lance M.; Husodo, Satrio; Meekins, David A.; Taylor, Adam O.; Turner, Benjamin D.; Auger, Kyle D.; Dukhande, Vikas V.; Chakravarthy, Srinivas; Sanz, Pascual; Woods, Virgil V.; Li, Sheng; Vander Kooi, Craig W.; Gentry, Matthew S.

    2015-01-01

    SUMMARY Glycogen is the major mammalian glucose storage cache and is critical for energy homeostasis. Glycogen synthesis in neurons must be tightly controlled, due to neuronal sensitivity to perturbations in glycogen metabolism. Lafora disease (LD) is a fatal, congenital, neurodegenerative epilepsy. Mutations in the gene encoding the glycogen phosphatase laforin result in hyperphosphorylated glycogen that forms water-insoluble inclusions called Lafora bodies (LBs). LBs induce neuronal apoptosis and are the causative agent of LD. The mechanism of glycogen dephosphorylation by laforin and dysfunction in LD is unknown. We report the crystal structure of laforin bound to phosphoglucan product, revealing its unique integrated tertiary and quaternary structure. Structure-guided mutagenesis combined with biophysical and biochemical analyses reveal the basis for normal function of laforin in glycogen metabolism. Analyses of LD patient mutations define the mechanism by which subsets of mutations disrupt laforin function. These data provide fundamental insights connecting glycogen metabolism to neurodegenerative disease. PMID:25544560

  7. The molecular size and shape of liver glycogen.

    PubMed

    Geddes, R; Harvey, J D; Wills, P R

    1977-05-01

    The molecular-weight distribution of liver glycogen has been established from the analysis of sedimentation rates of fractions separated on sucrose density gradients and from the direct measurement of the diffusion coefficients of these fractions by laser-intensity-fluctuation spectroscopy. Hydrodynamic studies indicated that all fractions of glycogen of mol.wt.exceeding 25x10(6) had about 1.1 g of water per g of polysaccharide associated with them. The hydration and hydrodynamic behaviour of all fractions of mol.wt. exceeding 25x10(6) was similar, whereas smaller fractions behaved anomalously, indicating a substantially different overall structure. PMID:869923

  8. The molecular size and shape of liver glycogen.

    PubMed Central

    Geddes, R; Harvey, J D; Wills, P R

    1977-01-01

    The molecular-weight distribution of liver glycogen has been established from the analysis of sedimentation rates of fractions separated on sucrose density gradients and from the direct measurement of the diffusion coefficients of these fractions by laser-intensity-fluctuation spectroscopy. Hydrodynamic studies indicated that all fractions of glycogen of mol.wt.exceeding 25x10(6) had about 1.1 g of water per g of polysaccharide associated with them. The hydration and hydrodynamic behaviour of all fractions of mol.wt. exceeding 25x10(6) was similar, whereas smaller fractions behaved anomalously, indicating a substantially different overall structure. PMID:869923

  9. Applications of mutant yeast strains with low glycogen storage capability

    NASA Technical Reports Server (NTRS)

    Petersen, G. R.; Schubert, W. W.; Stokes, B. O.

    1981-01-01

    Several strains of Hansenula polymorpha were selected for possible low glycogen storage characteristics based on a selective I2 staining procedure. The levels of storage carbohydrates in the mutant strains were found to be 44-70% of the levels in the parent strain for cultures harvested in stationary phase. Similar differences generally were not found for cells harvested in exponential phase. Yeast strains deficient in glycogen storage capability are valuable in increasing the relative protein value of microbial biomass and also may provide significant cost savings in substrate utilization in fermentative processes.

  10. Adipose tissue glycogen accumulation is associated with obesity-linked inflammation in humans

    PubMed Central

    Ceperuelo-Mallafré, Victòria; Ejarque, Miriam; Serena, Carolina; Duran, Xavier; Montori-Grau, Marta; Rodríguez, Miguel Angel; Yanes, Oscar; Núñez-Roa, Catalina; Roche, Kelly; Puthanveetil, Prasanth; Garrido-Sánchez, Lourdes; Saez, Enrique; Tinahones, Francisco J.; Garcia-Roves, Pablo M.; Gómez-Foix, Anna Ma; Saltiel, Alan R.; Vendrell, Joan; Fernández-Veledo, Sonia

    2015-01-01

    Objective Glycogen metabolism has emerged as a mediator in the control of energy homeostasis and studies in murine models reveal that adipose tissue might contain glycogen stores. Here we investigated the physio(patho)logical role of glycogen in human adipose tissue in the context of obesity and insulin resistance. Methods We studied glucose metabolic flux of hypoxic human adipoctyes by nuclear magnetic resonance and mass spectrometry-based metabolic approaches. Glycogen synthesis and glycogen content in response to hypoxia was analyzed in human adipocytes and macrophages. To explore the metabolic effects of enforced glycogen deposition in adipocytes and macrophages, we overexpressed PTG, the only glycogen-associated regulatory subunit (PP1-GTS) reported in murine adipocytes. Adipose tissue gene expression analysis was performed on wild type and homozygous PTG KO male mice. Finally, glycogen metabolism gene expression and glycogen accumulation was analyzed in adipose tissue, mature adipocytes and resident macrophages from lean and obese subjects with different degrees of insulin resistance in 2 independent cohorts. Results We show that hypoxia modulates glucose metabolic flux in human adipocytes and macrophages and promotes glycogenesis. Enforced glycogen deposition by overexpression of PTG re-orients adipocyte secretion to a pro-inflammatory response linked to insulin resistance and monocyte/lymphocyte migration. Furthermore, glycogen accumulation is associated with inhibition of mTORC1 signaling and increased basal autophagy flux, correlating with greater leptin release in glycogen-loaded adipocytes. PTG-KO mice have reduced expression of key inflammatory genes in adipose tissue and PTG overexpression in M0 macrophages induces a pro-inflammatory and glycolytic M1 phenotype. Increased glycogen synthase expression correlates with glycogen deposition in subcutaneous adipose tissue of obese patients. Glycogen content in subcutaneous mature adipocytes is associated

  11. AAV vector-mediated reversal of hypoglycemia in canine and murine glycogen storage disease type Ia.

    PubMed

    Koeberl, Dwight D; Pinto, Carlos; Sun, Baodong; Li, Songtao; Kozink, Daniel M; Benjamin, Daniel K; Demaster, Amanda K; Kruse, Meghan A; Vaughn, Valerie; Hillman, Steven; Bird, Andrew; Jackson, Mark; Brown, Talmage; Kishnani, Priya S; Chen, Yuan-Tsong

    2008-04-01

    Glycogen storage disease type Ia (GSD-Ia) profoundly impairs glucose release by the liver due to glucose-6-phosphatase (G6Pase) deficiency. An adeno-associated virus (AAV) containing a small human G6Pase transgene was pseudotyped with AAV8 (AAV2/8) to optimize liver tropism. Survival was prolonged in 2-week-old G6Pase (-/-) mice by 600-fold fewer AAV2/8 vector particles (vp), in comparison to previous experiments involving this model (2 x 10(9) vp; 3 x 10(11) vp/kg). When the vector was pseudotyped with AAV1, survival was prolonged only at a higher dose (3 x 10(13) vp/kg). The AAV2/8 vector uniquely prevented hypoglycemia during fasting and fully corrected liver G6Pase deficiency in GSD-Ia mice and dogs. The AAV2/8 vector has prolonged survival in three GSD-Ia dogs to >11 months, which validated this strategy in the large animal model for GSD-Ia. Urinary biomarkers, including lactate and 3-hydroxybutyrate, were corrected by G6Pase expression solely in the liver. Glycogen accumulation in the liver was reduced almost to the normal level in vector-treated GSD-Ia mice and dogs, as was the hepatocyte growth factor (HGF) in GSD-Ia mice. These preclinical data demonstrated the efficacy of correcting hepatic G6Pase deficiency, and support the further preclinical development of AAV vector-mediated gene therapy for GSD-Ia. PMID:18362924

  12. The Extracellular Redox State Modulates Mitochondrial Function, Gluconeogenesis, and Glycogen Synthesis in Murine Hepatocytes

    PubMed Central

    Nocito, Laura; Kleckner, Amber S.; Yoo, Elsia J.; Jones IV, Albert R.; Liesa, Marc; Corkey, Barbara E.

    2015-01-01

    Circulating redox state changes, determined by the ratio of reduced/oxidized pairs of different metabolites, have been associated with metabolic diseases. However, the pathogenic contribution of these changes and whether they modulate normal tissue function is unclear. As alterations in hepatic gluconeogenesis and glycogen metabolism are hallmarks that characterize insulin resistance and type 2 diabetes, we tested whether imposed changes in the extracellular redox state could modulate these processes. Thus, primary hepatocytes were treated with different ratios of the following physiological extracellular redox couples: β-hydroxybutyrate (βOHB)/acetoacetate (Acoc), reduced glutathione (GSH)/oxidized glutathione (GSSG), and cysteine/cystine. Exposure to a more oxidized ratio via extracellular βOHB/Acoc, GSH/GSSG, and cysteine/cystine in hepatocytes from fed mice increased intracellular hydrogen peroxide without causing oxidative damage. On the other hand, addition of more reduced ratios of extracellular βOHB/Acoc led to increased NAD(P)H and maximal mitochondrial respiratory capacity in hepatocytes. Greater βOHB/Acoc ratios were also associated with decreased β-oxidation, as expected with enhanced lipogenesis. In hepatocytes from fasted mice, a more extracellular reduced state of βOHB/Acoc led to increased alanine-stimulated gluconeogenesis and enhanced glycogen synthesis capacity from added glucose. Thus, we demonstrated for the first time that the extracellular redox state regulates the major metabolic functions of the liver and involves changes in intracellular NADH, hydrogen peroxide, and mitochondrial respiration. Because redox state in the blood can be communicated to all metabolically sensitive tissues, this work confirms the hypothesis that circulating redox state may be an important regulator of whole body metabolism and contribute to alterations associated with metabolic diseases. PMID:25816337

  13. Aroclor 1254 disrupts liver glycogen metabolism and enhances acute stressor-mediated glycogenolysis in rainbow trout.

    PubMed

    Wiseman, Steve; Vijayan, Mathilakath M

    2011-09-01

    The objective of this study was to investigate the impact of short-term exposure to polychlorinated biphenyls on the acute stress response in rainbow trout. Fish were exposed to dietary Aroclor1254 (10mg kg(-1) body mass/day) for 3 days and then subjected to a 3-min handling disturbance and sampled over a 24h recovery after the stressor exposure. In the pre-stress fish, PCB exposure significantly elevated aryl hydrocarbon receptor (AhR) and cytochrome P4501A1 (Cyp1A1) mRNA abundance and Cyp1A protein expression confirming AhR activation. There was no significant effect of PCB on plasma cortisol and glucose levels, while plasma lactate levels were significantly elevated compared to the sham group. PCB exposure significantly elevated liver glycogen content and hexokinase activity, whereas lactate dehydrogenase activity was depressed. Short-term PCB exposure did not modify the acute stressor-induced plasma cortisol, glucose and lactate responses. Liver glycogen content dropped significantly after stressor exposure in the PCB group but not in the sham group. This was matched by a significantly higher liver LDH activity and a lower HK activity during recovery in the PCB group suggesting enhanced glycolytic capacity to fuel hepatic metabolism. Liver AhR, but not Cyp1A1, transcript levels were significantly reduced during recovery from handling stressor in the Aroclor fed fish. Collectively, this study demonstrates that short-term PCB exposure may impair the liver metabolic performance that is critical to cope with the enhanced energy demand associated with additional stressor exposure in rainbow trout. PMID:21745595

  14. Fasting-Induced Protein Phosphatase 1 Regulatory Subunit Contributes to Postprandial Blood Glucose Homeostasis via Regulation of Hepatic Glycogenesis

    PubMed Central

    Luo, Xiaolin; Zhang, Yongxian; Ruan, Xiangbo; Jiang, Xiaomeng; Zhu, Lu; Wang, Xiao; Ding, Qiurong; Liu, Weizhong; Pan, Yi; Wang, Zhenzhen; Chen, Yan

    2011-01-01

    OBJECTIVE Most animals experience fasting–feeding cycles throughout their lives. It is well known that the liver plays a central role in regulating glycogen metabolism. However, how hepatic glycogenesis is coordinated with the fasting–feeding cycle to control postprandial glucose homeostasis remains largely unknown. This study determines the molecular mechanism underlying the coupling of hepatic glycogenesis with the fasting–feeding cycle. RESEARCH DESIGN AND METHODS Through a series of molecular, cellular, and animal studies, we investigated how PPP1R3G, a glycogen-targeting regulatory subunit of protein phosphatase 1 (PP1), is implicated in regulating hepatic glycogenesis and glucose homeostasis in a manner tightly orchestrated with the fasting–feeding cycle. RESULTS PPP1R3G in the liver is upregulated during fasting and downregulated after feeding. PPP1R3G associates with glycogen pellet, interacts with the catalytic subunit of PP1, and regulates glycogen synthase (GS) activity. Fasting glucose level is reduced when PPP1R3G is overexpressed in the liver. Hepatic knockdown of PPP1R3G reduces postprandial elevation of GS activity, decreases postprandial accumulation of liver glycogen, and decelerates postprandial clearance of blood glucose. Other glycogen-targeting regulatory subunits of PP1, such as PPP1R3B, PPP1R3C, and PPP1R3D, are downregulated by fasting and increased by feeding in the liver. CONCLUSIONS We propose that the opposite expression pattern of PPP1R3G versus other PP1 regulatory subunits comprise an intricate regulatory machinery to control hepatic glycogenesis during the fasting–feeding cycle. Because of its unique expression pattern, PPP1R3G plays a major role to control postprandial glucose homeostasis during the fasting–feeding transition via its regulation on liver glycogenesis. PMID:21471512

  15. Hepatitis Vaccines.

    PubMed

    Ogholikhan, Sina; Schwarz, Kathleen B

    2016-01-01

    Viral hepatitis is a serious health problem all over the world. However, the reduction of the morbidity and mortality due to vaccinations against hepatitis A and hepatitis B has been a major component in the overall reduction in vaccine preventable diseases. We will discuss the epidemiology, vaccine development, and post-vaccination effects of the hepatitis A and B virus. In addition, we discuss attempts to provide hepatitis D vaccine for the 350 million individuals infected with hepatitis B globally. Given the lack of a hepatitis C vaccine, the many challenges facing the production of a hepatitis C vaccine will be shown, along with current and former vaccination trials. As there is no current FDA-approved hepatitis E vaccine, we will present vaccination data that is available in the rest of the world. Finally, we will discuss the existing challenges and questions facing future endeavors for each of the hepatitis viruses, with efforts continuing to focus on dramatically reducing the morbidity and mortality associated with these serious infections of the liver. PMID:26978406

  16. Hepatitis Vaccines

    PubMed Central

    Ogholikhan, Sina; Schwarz, Kathleen B.

    2016-01-01

    Viral hepatitis is a serious health problem all over the world. However, the reduction of the morbidity and mortality due to vaccinations against hepatitis A and hepatitis B has been a major component in the overall reduction in vaccine preventable diseases. We will discuss the epidemiology, vaccine development, and post-vaccination effects of the hepatitis A and B virus. In addition, we discuss attempts to provide hepatitis D vaccine for the 350 million individuals infected with hepatitis B globally. Given the lack of a hepatitis C vaccine, the many challenges facing the production of a hepatitis C vaccine will be shown, along with current and former vaccination trials. As there is no current FDA-approved hepatitis E vaccine, we will present vaccination data that is available in the rest of the world. Finally, we will discuss the existing challenges and questions facing future endeavors for each of the hepatitis viruses, with efforts continuing to focus on dramatically reducing the morbidity and mortality associated with these serious infections of the liver. PMID:26978406

  17. Glycogen storage disease type Ia in two littermate Maltese puppies.

    PubMed

    Brix, A E; Howerth, E W; McConkie-Rosell, A; Peterson, D; Egnor, D; Wells, M R; Chen, Y T

    1995-09-01

    Glycogen storage disease type Ia (GSD-Ia) (von Gierke's disease) was identified in two 47-day-old littermate Maltese puppies. The puppies were presented for necropsy with a history of failure to thrive, mental depression, and poor body condition. Gross findings included small body size and emaciation (212 and 246 g versus 595 g for normal littermate), severely enlarged pale livers (48 and 61 g), and pale kidneys. Histologically, there was marked diffuse vacuolation of hepatocytes with large amounts of glycogen and small amounts of lipid. Renal tubular epithelium was mildly to moderately vacuolated. Soft tissue mineralization was present in renal tubules and pulmonary alveolar septa. Biochemical analysis showed that levels of glucose-6-phosphatase were markedly reduced in liver (0.3 and 0.4 microM/minute/g tissue versus 4.7 +/- 1.5 microM/minute/g tissue for controls) and kidney (0.45 and 0.4 microM/minute/g tissue versus 4.1 microM/minute/g tissue for controls) and that glycogen content was increased in liver (9.4% and 9.4% versus 1.3% +/- 1.4% for controls). This is the first confirmed report of animals with glycogen storage disease type Ia. PMID:8578635

  18. Muscle glycogen supercompensation: absence of a gender-related difference.

    PubMed

    James, A P; Lorraine, M; Cullen, D; Goodman, C; Dawson, B; Palmer, T N; Fournier, P A

    2001-10-01

    Recently it has been reported that women do not have the capacity to accumulate supranormal levels of muscle glycogen when subjected to a carbohydrate (CHO) loading regimen [Tarnopolsky et al. (1995) J Appl Physiol 78:1360-1368]. Since, in this study, CHO intake relative to body mass in the female subjects was much lower than that in males, our primary aim was to re-examine this issue using subjects fed comparable amounts of CHO. Endurance-trained female and male subjects ingested 12 g CHO x kg(-1) lean body mass day(-1) in conjunction with the cessation of their daily physical training. A 3-day exposure to this diet resulted in a marked rise in muscle glycogen levels from [mean (SD)] 108 (15) mmol x kg(-1) wet weight to 193 (14) mmol x kg(-1) wet weight and 111 (16) m mol x kg(-1) wet weight to 202 (20) mmol x kg(-1) wet weight in the female participants during the post-menstrual and pre-menstrual phases of their menstrual cycle, respectively, and from 109 (27) mmol x kg(-1) wet weight to 183 (25) mmol x kg(-1) wet weight in males. We conclude that (1) female athletes have the capacity to accumulate supranormal levels of muscle glycogen, and (2) when exercise-trained males and females are fed comparable amounts of CHO relative to lean body mass, there is no gender-related difference in their ability to accumulate supranormal levels of muscle glycogen. PMID:11718281

  19. The Role of Skeletal Muscle Glycogen Breakdown for Regulation of Insulin Sensitivity by Exercise

    PubMed Central

    Jensen, Jørgen; Rustad, Per Inge; Kolnes, Anders Jensen; Lai, Yu-Chiang

    2011-01-01

    Glycogen is the storage form of carbohydrates in mammals. In humans the majority of glycogen is stored in skeletal muscles (∼500 g) and the liver (∼100 g). Food is supplied in larger meals, but the blood glucose concentration has to be kept within narrow limits to survive and stay healthy. Therefore, the body has to cope with periods of excess carbohydrates and periods without supplementation. Healthy persons remove blood glucose rapidly when glucose is in excess, but insulin-stimulated glucose disposal is reduced in insulin resistant and type 2 diabetic subjects. During a hyperinsulinemic euglycemic clamp, 70–90% of glucose disposal will be stored as muscle glycogen in healthy subjects. The glycogen stores in skeletal muscles are limited because an efficient feedback-mediated inhibition of glycogen synthase prevents accumulation. De novo lipid synthesis can contribute to glucose disposal when glycogen stores are filled. Exercise physiologists normally consider glycogen’s main function as energy substrate. Glycogen is the main energy substrate during exercise intensity above 70% of maximal oxygen uptake (Vo2max⁡) and fatigue develops when the glycogen stores are depleted in the active muscles. After exercise, the rate of glycogen synthesis is increased to replete glycogen stores, and blood glucose is the substrate. Indeed insulin-stimulated glucose uptake and glycogen synthesis is elevated after exercise, which, from an evolutional point of view, will favor glycogen repletion and preparation for new “fight or flight” events. In the modern society, the reduced glycogen stores in skeletal muscles after exercise allows carbohydrates to be stored as muscle glycogen and prevents that glucose is channeled to de novo lipid synthesis, which over time will causes ectopic fat accumulation and insulin resistance. The reduction of skeletal muscle glycogen after exercise allows a healthy storage of carbohydrates after meals and prevents development of type 2

  20. Substrate availability for long-chain base formation as a regulator of hepatic sphingolipid and cholesterol biosynthesis

    SciTech Connect

    Messmer, T.O.; Merrill, A.H. Jr.

    1986-03-05

    The de novo biosynthesis of the sphinganine and sphingosine backbones of sphingolipids was studied with isolated rat hepatocytes and established liver cell lines. The rate of incorporation of radiolabel from (/sup 14/C)-serine by intact cells was half maximal at 0.3 mM, which is similar to the K/sub m/ of the initial enzyme of this pathway and in vivo concentrations of this substrate. Long-chain base biosynthesis was stimulated by another precursor, palmitic acid, but other fatty acids were inhibitory. Hepatocytes isolated from fed and fasted rats had different rates of sphingolipid formation, which may also reflect the relative levels of palmitoyl-CoA. These results established that the availability of the precursors of long-chain base formation, serine and palmitic acid, is a major factor in the regulation of this pathway. Since sphingomyelin biosynthesis could be modified, its relationship to cholesterol metabolism was also examined. Both hepatocytes and cultured liver cells in high serine (0.6mM) had increased incorporation of (/sup 14/C)-acetate into cholesterol (13%, P < 0.05 and 50%, P < 0.01, respectively). These results indicate that sphingolipid and cholesterol biosynthesis are coordinately regulated, perhaps because these lipids are located in similar membranes and lipoproteins.

  1. Nrf2-Mediated Regulation of Skeletal Muscle Glycogen Metabolism.

    PubMed

    Uruno, Akira; Yagishita, Yoko; Katsuoka, Fumiki; Kitajima, Yasuo; Nunomiya, Aki; Nagatomi, Ryoichi; Pi, Jingbo; Biswal, Shyam S; Yamamoto, Masayuki

    2016-06-01

    Nrf2 (NF-E2-related factor 2) contributes to the maintenance of glucose homeostasis in vivo Nrf2 suppresses blood glucose levels by protecting pancreatic β cells from oxidative stress and improving peripheral tissue glucose utilization. To elucidate the molecular mechanisms by which Nrf2 contributes to the maintenance of glucose homeostasis, we generated skeletal muscle (SkM)-specific Keap1 knockout (Keap1MuKO) mice that express abundant Nrf2 in their SkM and then examined Nrf2 target gene expression in that tissue. In Keap1MuKO mice, blood glucose levels were significantly downregulated and the levels of the glycogen branching enzyme (Gbe1) and muscle-type PhKα subunit (Phka1) mRNAs, along with those of the glycogen branching enzyme (GBE) and the phosphorylase b kinase α subunit (PhKα) protein, were significantly upregulated in mouse SkM. Consistent with this result, chemical Nrf2 inducers promoted Gbe1 and Phka1 mRNA expression in both mouse SkM and C2C12 myotubes. Chromatin immunoprecipitation analysis demonstrated that Nrf2 binds the Gbe1 and Phka1 upstream promoter regions. In Keap1MuKO mice, muscle glycogen content was strongly reduced and forced GBE expression in C2C12 myotubes promoted glucose uptake. Therefore, our results demonstrate that Nrf2 induction in SkM increases GBE and PhKα expression and reduces muscle glycogen content, resulting in improved glucose tolerance. Our results also indicate that Nrf2 differentially regulates glycogen metabolism in SkM and the liver. PMID:27044864

  2. Supercompensation of muscle glycogen in trained and untrained subjects.

    PubMed

    Roedde, S; MacDougall, J D; Sutton, J R; Green, H J

    1986-03-01

    The purpose of this study was to determine whether or not trained athletes have the same capacity for supercompensation of muscle glycogen as untrained subjects. Muscle glycogen was measured in 4 highly trained cyclists and 4 untrained controls over a 6 day period of exercise and dietary manipulation. During the week prior to the investigation the trained group tapered their training load but maintained a high carbohydrate intake as they would in preparation for a major competition. Needle biopsies were taken from the vastus lateralis before and after exhaustive cycle ergometry at 73% VO2 max followed by several sprint intervals, after 3 days on a carbohydrate-restricted diet and after 2 and 3 days on a high carbohydrate diet. All food intake was quantified and plasma insulin and glucose were monitored daily. The mean initial glycogen concentration for the trained group was 115 mmol X kg-1 wet muscle weight and 92 mmol X kg-1 for the untrained group. Both groups showed similar post exercise depletion and recovery patterns when expressed as a % of their initial values. Following 3 days of high carbohydrate diet, the glycogen concentration for the trained cyclists reached 174 mmol X kg-1 or 152% of its initial value while the untrained-group reached 143 mmol X kg-1 or 155% of its initial value. It was concluded that a regimen of exhaustive exercise, followed by a period of carbohydrate restriction and a period of high carbohydrate intake, results in substantially higher muscle glycogen storage than can be achieved by a reduction in training in combination with high carbohydrate intake.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:3698159

  3. Hepatitis B Vaccine

    MedlinePlus

    ... as a combination product containing Hepatitis A Vaccine, Hepatitis B Vaccine) ... What is hepatitis B?Hepatitis B is a serious infection that affects the liver. It is caused by the hepatitis B virus. ...

  4. Hepatitis A Vaccine

    MedlinePlus

    Twinrix® (as a combination product containing Hepatitis A Vaccine, Hepatitis B Vaccine) ... What is hepatitis A?Hepatitis A is a serious liver disease caused by the hepatitis A virus (HAV). HAV is found in ...

  5. Hepatitis C: Clinical Trials

    MedlinePlus

    ... and Public Home » Hepatitis C » Treatment Decisions Viral Hepatitis Menu Menu Viral Hepatitis Viral Hepatitis Home For ... can I find out about participating in a hepatitis C clinical trial? Many trials are being conducted ...

  6. Development and characterization of a new human hepatic cell line.

    PubMed

    Ramboer, Eva; De Craene, Bram; De Kock, Joey; Berx, Geert; Rogiers, Vera; Vanhaecke, Tamara; Vinken, Mathieu

    2015-01-01

    The increasing demand and hampered use of primary human hepatocytes for research purposes have urged scientists to search for alternative cell sources, such as immortalized hepatic cell lines. The aim of this study was to develop a human hepatic cell line using the combined overexpression of TERT and the cell cycle regulators cyclin D1 and mutant isoform CDK4R24C. Following transduction of adult human primary hepatocytes with the selected immortalization genes, cell growth was triggered and a cell line was established. When cultured under appropriate conditions, the cell line expressed several hepatocytic markers and liver-enriched transcription factors at the transcriptional and/or translational level, secreted liver-specific proteins and showed glycogen deposition. These results suggest that the immortalization strategy applied to primary human hepatocytes could generate a novel hepatic cell line that seems to retain some key hepatic characteristics. PMID:26869867

  7. Development and characterization of a new human hepatic cell line

    PubMed Central

    Ramboer, Eva; De Craene, Bram; De Kock, Joey; Berx, Geert; Rogiers, Vera; Vanhaecke, Tamara; Vinken, Mathieu

    2015-01-01

    The increasing demand and hampered use of primary human hepatocytes for research purposes have urged scientists to search for alternative cell sources, such as immortalized hepatic cell lines. The aim of this study was to develop a human hepatic cell line using the combined overexpression of TERT and the cell cycle regulators cyclin D1 and mutant isoform CDK4R24C. Following transduction of adult human primary hepatocytes with the selected immortalization genes, cell growth was triggered and a cell line was established. When cultured under appropriate conditions, the cell line expressed several hepatocytic markers and liver-enriched transcription factors at the transcriptional and/or translational level, secreted liver-specific proteins and showed glycogen deposition. These results suggest that the immortalization strategy applied to primary human hepatocytes could generate a novel hepatic cell line that seems to retain some key hepatic characteristics. PMID:26869867

  8. Autoimmune hepatitis

    MedlinePlus

    ... diseases. These include: Graves disease Inflammatory bowel disease Rheumatoid arthritis Scleroderma Sjogren syndrome Systemic lupus erythematosus Thyroiditis Type 1 diabetes Ulcerative colitis Autoimmune hepatitis may occur in family ...

  9. Hepatitis B

    MedlinePlus

    ... A Hepatitis B HPV (Human Papillomavirus) Influenza (Flu) Measles Meningococcal Disease Mumps Pertussis (Whooping Cough) Pneumococcal Disease Rubella (German Measles) Shingles (Herpes Zoster) Tetanus (Lockjaw) Professional Resources Adult ...

  10. N-Acetyl-beta-D-glucopyranosylamine 6-phosphate is a specific inhibitor of glycogen-bound protein phosphatase 1.

    PubMed Central

    Board, M

    1997-01-01

    Previous work has shown that the C-1-substituted glucose-analogue N-acetyl-beta-D-glucopyranosylamine (1-GlcNAc) is a competitive inhibitor of glycogen phosphorylase (GP) and stimulates the inactivation of this enzyme by GP phosphatase. In addition to its effects on GP, 1-GlcNAc also prevents the glucose-led activation of glycogen synthase (GS) in whole hepatocytes. Such an effect on GS was thought to be due to the formation of 1-GlcNAc-6-P by the action of glucokinase within the hepatocyte [Board, Bollen, Stalmans, Kim, Fleet and Johnson (1995) Biochem. J. 311, 845-852]. To investigate this possibility further, a pure preparation of 1-GlcNAc-6-P was synthesized. The effects of the phosphorylated glucose analogue on the activity of protein phosphatase 1 (PP1), the enzyme responsible for dephosphorylation and activation of GS, are reported. During the present study, 1-GlcNAc-6-P inhibited the activity of the glycogen-bound form of PP1, affecting both the GSb phosphatase and GPa phosphatase activities. A level of 50% inhibition of GSb phosphatase activity was achieved with 85 microM 1-GlcNAc-6-P in the absence of Glc-6-P and with 135 microM in the presence of 10 mM Glc-6-P. At either Glc-6-P concentration, 500 microM 1-GlcNAc-6-P completely inhibited activity. The Glc-6-P stimulation of the GPa phosphatase activity of PP1 was negated by 1-GlcNAc-6-P but there was no inhibition of the basal rate in the absence of Glc-6-P. 1-GlcNAc-6-P inhibition was specific for the glycogen-bound form of PP1 and did not inhibit the GSb phosphatase activity of the cytosolic form of the enzyme. The present work explains our previous observations on the inactivating effects on GS of incubating whole hepatocytes with 1-GlcNAc. These observations have their basis in the inhibition of glycogen-bound PP1 by 1-GlcNAc-6-P. A novel inhibitor of PP1, specific for the glycogen-bound form of the enzyme, is presented. PMID:9371733