The Experts below are selected from a list of 19371 Experts worldwide ranked by ideXlab platform

Jose M Serratosa - One of the best experts on this subject based on the ideXlab platform.

  • lafora disease offers a unique window into neuronal Glycogen Metabolism
    Journal of Biological Chemistry, 2018
    Co-Authors: Matthew S Gentry, Joan J Guinovart, Peter J. Roach, Jose M Serratosa, Berge A. Minassian
    Abstract:

    Lafora disease (LD) is a fatal, autosomal recessive, Glycogen-storage disorder that manifests as severe epilepsy. LD results from mutations in the gene encoding either the Glycogen phosphatase laforin or the E3 ubiquitin ligase malin. Individuals with LD develop cytoplasmic, aberrant Glycogen inclusions in nearly all tissues that more closely resemble plant starch than human Glycogen. This Minireview discusses the unique window into Glycogen Metabolism that LD research offers. It also highlights recent discoveries, including that Glycogen contains covalently bound phosphate and that neurons synthesize Glycogen and express both Glycogen synthase and Glycogen phosphorylase.

Joan J Guinovart - One of the best experts on this subject based on the ideXlab platform.

Rene Koopman - One of the best experts on this subject based on the ideXlab platform.

  • dysfunctional muscle and liver Glycogen Metabolism in mdx dystrophic mice
    PLOS ONE, 2014
    Co-Authors: David Stapleton, Xianzhong Lau, Marcelo Flores, Jennifer Trieu, Stefan M Gehrig, Annabel Chee, Timur Naim, Gordon S Lynch, Rene Koopman
    Abstract:

    Background Duchenne muscular dystrophy (DMD) is a severe, genetic muscle wasting disorder characterised by progressive muscle weakness. DMD is caused by mutations in the dystrophin (dmd) gene resulting in very low levels or a complete absence of the dystrophin protein, a key structural element of muscle fibres which is responsible for the proper transmission of force. In the absence of dystrophin, muscle fibres become damaged easily during contraction resulting in their degeneration. DMD patients and mdx mice (an animal model of DMD) exhibit altered metabolic disturbances that cannot be attributed to the loss of dystrophin directly. We tested the hypothesis that Glycogen Metabolism is defective in mdx dystrophic mice. Results Dystrophic mdx mice had increased skeletal muscle Glycogen (79%, (P<0.01)). Skeletal muscle Glycogen synthesis is initiated by Glycogenin, the expression of which was increased by 50% in mdx mice (P<0.0001). Glycogen synthase activity was 12% higher (P<0.05) but Glycogen branching enzyme activity was 70% lower (P<0.01) in mdx compared with wild-type mice. The rate-limiting enzyme for Glycogen breakdown, Glycogen phosphorylase, had 62% lower activity (P<0.01) in mdx mice resulting from a 24% reduction in PKA activity (P<0.01). In mdx mice Glycogen debranching enzyme expression was 50% higher (P<0.001) together with starch-binding domain protein 1 (219% higher; P<0.01). In addition, mdx mice were glucose intolerant (P<0.01) and had 30% less liver Glycogen (P<0.05) compared with control mice. Subsequent analysis of the enzymes dysregulated in skeletal muscle Glycogen Metabolism in mdx mice identified reduced Glycogenin protein expression (46% less; P<0.05) as a possible cause of this phenotype. Conclusion We identified that mdx mice were glucose intolerant, and had increased skeletal muscle Glycogen but reduced amounts of liver Glycogen.

David Stapleton - One of the best experts on this subject based on the ideXlab platform.

  • dysfunctional muscle and liver Glycogen Metabolism in mdx dystrophic mice
    PLOS ONE, 2014
    Co-Authors: David Stapleton, Xianzhong Lau, Marcelo Flores, Jennifer Trieu, Stefan M Gehrig, Annabel Chee, Timur Naim, Gordon S Lynch, Rene Koopman
    Abstract:

    Background Duchenne muscular dystrophy (DMD) is a severe, genetic muscle wasting disorder characterised by progressive muscle weakness. DMD is caused by mutations in the dystrophin (dmd) gene resulting in very low levels or a complete absence of the dystrophin protein, a key structural element of muscle fibres which is responsible for the proper transmission of force. In the absence of dystrophin, muscle fibres become damaged easily during contraction resulting in their degeneration. DMD patients and mdx mice (an animal model of DMD) exhibit altered metabolic disturbances that cannot be attributed to the loss of dystrophin directly. We tested the hypothesis that Glycogen Metabolism is defective in mdx dystrophic mice. Results Dystrophic mdx mice had increased skeletal muscle Glycogen (79%, (P<0.01)). Skeletal muscle Glycogen synthesis is initiated by Glycogenin, the expression of which was increased by 50% in mdx mice (P<0.0001). Glycogen synthase activity was 12% higher (P<0.05) but Glycogen branching enzyme activity was 70% lower (P<0.01) in mdx compared with wild-type mice. The rate-limiting enzyme for Glycogen breakdown, Glycogen phosphorylase, had 62% lower activity (P<0.01) in mdx mice resulting from a 24% reduction in PKA activity (P<0.01). In mdx mice Glycogen debranching enzyme expression was 50% higher (P<0.001) together with starch-binding domain protein 1 (219% higher; P<0.01). In addition, mdx mice were glucose intolerant (P<0.01) and had 30% less liver Glycogen (P<0.05) compared with control mice. Subsequent analysis of the enzymes dysregulated in skeletal muscle Glycogen Metabolism in mdx mice identified reduced Glycogenin protein expression (46% less; P<0.05) as a possible cause of this phenotype. Conclusion We identified that mdx mice were glucose intolerant, and had increased skeletal muscle Glycogen but reduced amounts of liver Glycogen.

Igor Allaman - One of the best experts on this subject based on the ideXlab platform.

  • Glial Glycogen Metabolism
    Encyclopedia of Neuroscience, 2015
    Co-Authors: Igor Allaman
    Abstract:

    Glycogen represents the largest energy reserve of the brain and is almost quite exclusively localized in astrocytes. In the first part of this article, a summary of our knowledge concerning brain Glycogen Metabolism and its regulation is presented. The second part focuses on potential evidence that Glycogen can serve as energy substrate during neuronal activation, as well as on the role of brain Glycogen as an emergency reserve in case of insufficient energy supply. These data are discussed in reference to the emerging concept of neuron–glia metabolic interactions

  • Glycogen Metabolism and the homeostatic regulation of sleep
    Metabolic Brain Disease, 2014
    Co-Authors: Jean-marie Petit, Pierre J. Magistretti, Sophie Burlet-godinot, Igor Allaman
    Abstract:

    In 1995 Benington and Heller formulated an energy hypothesis of sleep centered on a key role of Glycogen. It was postulated that a major function of sleep is to replenish Glycogen stores in the brain that have been depleted during wakefulness which is associated to an increased energy demand. Astrocytic Glycogen depletion participates to an increase of extracellular adenosine release which influences sleep homeostasis. Here, we will review some evidence obtained by studies addressing the question of a key role played by Glycogen Metabolism in sleep regulation as proposed by this hypothesis or by an alternative hypothesis named “Glycogenetic” hypothesis as well as the importance of the confounding effect of glucocorticoids. Even though actual collected data argue in favor of a role of sleep in brain energy balance-homeostasis, they do not support a critical and direct involvement of Glycogen Metabolism on sleep regulation. For instance, Glycogen levels during the sleep-wake cycle are driven by different physiological signals and therefore appear more as a marker-integrator of brain energy status than a direct regulator of sleep homeostasis. In support of this we provide evidence that blockade of Glycogen mobilization does not induce more sleep episodes during the active period while locomotor activity is reduced. These observations do not invalidate the energy hypothesis of sleep but indicate that underlying cellular mechanisms are more complex than postulated by Benington and Heller.

  • Glycogen Metabolism as a Marker of Astrocyte Differentiation
    Journal of Cerebral Blood Flow and Metabolism, 2009
    Co-Authors: J.f. Brunet, Igor Allaman, Pierre J. Magistretti, Luc Pellerin
    Abstract:

    Glycogen is a hallmark of mature astrocytes, but its emergence during astrocytic differentiation is unclear. Differentiation of E14 mouse neurospheres into astrocytes was induced with fetal bovine serum (FBS), Leukemia Inhibitory Factor (LIF), or Ciliary Neurotrophic Factor (CNTF). Cytochemical and enzymatic analyses showed that Glycogen is present in FBS- or LIF- but not in CNTF-differentiated astrocytes. Glycogenolysis was induced in FBS- and LIF-differentiated astrocytes but Glycogen resynthesis was observed only with FBS. Protein targeting to Glycogen mRNA expression appeared with glial fibrillary acidic protein and S100β in FBS and LIF conditions but not with CNTF. These results show that Glycogen Metabolism constitutes a useful marker of astrocyte differentiation.

  • Sleep deprivation modulates brain mRNAs encoding genes of Glycogen Metabolism.
    European Journal of Neuroscience, 2002
    Co-Authors: Jean-marie Petit, Igor Allaman, Irene Tobler, Alexander A. Borbély, Pierre J. Magistretti
    Abstract:

    Replenishment of brain Glycogen stores depleted during waking has been suggested to constitute one of the functions of sleep [Benington, J. H. & Heller H. C. (1995) Prog. Neurobiol., 45, 347]. We have tested the hypothesis that the level of expression of enzymes involved in Glycogen Metabolism could undergo variations throughout the sleep-waking or rest-activity cycle, and after 6 h of 'gentle' total sleep deprivation in mice. Specifically, we determined the variations in mRNAs coding for protein targeting to Glycogen (PTG), Glycogen synthase and Glycogen phosphorylase, all considered as key regulators of Glycogen Metabolism. Glycogen synthase and Glycogen phosphorylase mRNAs exhibited significant variations throughout the light-dark cycle with a maximum at the middle of the light period and a minimum at the middle of the dark period. Following sleep deprivation, a two-fold increase in PTG mRNA and a decrease of mRNAs encoding Glycogen synthase and Glycogen phosphorylase were observed. These transcriptional events have functional consequences as the activity of Glycogen synthase was increased 2.5-fold indicating a stimulating effect of sleep deprivation on Glycogen synthesis. These results indicate that (i) expression of genes related to brain Glycogen Metabolism exhibit variations throughout the sleep-waking or rest-activity cycle and (ii) given the almost selective localization of Glycogen to astrocytes, these cells might participate in the regulation of sleep.