Astrocytic glycogen accumulation drives the pathophysiology of neurodegeneration in Lafora disease

Brain ◽  
2021 ◽  
Author(s):  
Jordi Duran ◽  
Arnau Hervera ◽  
Kia H Markussen ◽  
Olga Varea ◽  
Iliana López-Soldado ◽  
...  
Keyword(s):  
Mouse Model ◽  
Neurodegenerative Disorder ◽  
Glycogen Synthase ◽  
Glycogen Synthesis ◽  
Glycogen Metabolism ◽  
Cell Type ◽  
Lafora Disease ◽  
Glycogen Accumulation ◽  
Lafora Bodies

Abstract The hallmark of Lafora disease, a fatal neurodegenerative disorder, is the accumulation of intracellular glycogen aggregates, called Lafora bodies. Until recently, it was widely believed that brain Lafora bodies were present exclusively in neurons and thus that Lafora disease pathology derived from their accumulation in this cell population. However, recent evidence indicates that Lafora bodies are also present in astrocytes. To define the role of astrocytic Lafora bodies in Lafora disease pathology, we deleted glycogen synthase specifically from astrocytes in a mouse model of the disease (malinKO). Strikingly, blocking glycogen synthesis in astrocytes—thus impeding Lafora bodies accumulation in this cell type—prevented the increase in neurodegeneration markers, autophagy impairment, and metabolic changes characteristic of the malinKO model. Conversely, mice that overaccumulate glycogen in astrocytes showed an increase in these markers. These results unveil the deleterious consequences of the deregulation of glycogen metabolism in astrocytes and change the perspective that Lafora disease is caused solely by alterations in neurons.

scholarly journals Heating after intense repeated contractions inhibits glycogen accumulation in mouse EDL muscle: role of phosphorylase in postexercise glycogen metabolism

2018 ◽  
Vol 315 (5) ◽  
pp. C706-C713 ◽  
Author(s):  
Sarah J. Blackwood ◽  
Ester Hanya ◽  
Abram Katz
Keyword(s):  
Glycogen Synthase ◽  
Glycogen Synthesis ◽  
Glycogen Metabolism ◽  
Type Ii ◽  
Muscle Type ◽  
Phosphorylase Activity ◽  
Glycogen Accumulation ◽  
Longus Muscle ◽  
Edl Muscle

The effects of heating on glycogen synthesis (incorporation of [14C]glucose into glycogen) and accumulation after intense repeated contractions were investigated. Isolated mouse extensor digitorum longus muscle (type II) was stimulated electrically to perform intense tetanic contractions at 25°C. After 120 min recovery at 25°C, glycogen accumulated to almost 80% of basal, whereas after recovery at 35°C, glycogen remained low (~25% of basal). Glycogen synthesis averaged 0.97 ± 0.07 µmol·30 min−1·g wet wt−1 during recovery at 25°C and 1.48 ± 0.08 during recovery at 35°C ( P < 0.001). There were no differences in phosphorylase and glycogen synthase total activities nor in phosphorylase fractional activity, whereas glycogen synthase fractional activity was increased by ~50% after recovery at 35°C vs. 25°C. Inorganic phosphate (Pi, substrate for phosphorylase) was markedly increased (~300% of basal) following contraction but returned to control levels after 120 min recovery at 25°C. In contrast, Pi remained elevated after recovery at 35°C (>2-fold higher than recovery at 25°C). Estimates of glycogen breakdown indicated that phosphorylase activity (either via inhibition at 25°C or activation at 35°C) was responsible for ~60% of glycogen accumulation during recovery at 25°C and ~45% during recovery at 35°C. These data demonstrate that despite the enhancing effect of heating on glycogen synthesis during recovery from intense contractions, glycogen accumulation is inhibited owing to Pi-mediated activation of phosphorylase. Thus phosphorylase can play a quantitatively important role in glycogen biogenesis during recovery from repeated contractions in isolated type II muscle.

scholarly journals Gys1 antisense therapy rescues neuropathological bases of murine Lafora disease

2021 ◽  
Author(s):  
Saija Ahonen ◽  
Silvia Nitschke ◽  
Tamar R. Grossman ◽  
Holly Kordasiewicz ◽  
Peixiang Wang ◽  
...  
Keyword(s):  
Antisense Oligonucleotide ◽  
Glycogen Synthase ◽  
Lafora Disease ◽  
Neuroinflammatory Response ◽  
Glycogen Accumulation ◽  
Body Formation ◽  
Lafora Bodies ◽  
Progressive Myoclonus Epilepsy ◽  
Myoclonus Epilepsy ◽  
Lafora Body

AbstractLafora disease is a fatal progressive myoclonus epilepsy. At root, it is due to constant acquisition of branches that are too long in a subgroup of glycogen molecules, leading them to precipitate and accumulate into Lafora bodies, which drive a neuroinflammatory response and neurodegeneration. As a potential therapy, we aimed to downregulate glycogen synthase, the enzyme responsible for glycogen branch elongation, in the disease’s mouse models. We synthesized an antisense oligonucleotide (Gys1-ASO) that targets the mRNA of the brain-expressed glycogen synthase 1 gene (Gys1). We administered Gys1-ASO by intracerebroventricular injection and analyzed the pathological hallmarks of Lafora disease, namely glycogen accumulation, Lafora body formation, and neuroinflammation. Gys1-ASO prevented Lafora body formation in young mice that had not yet formed them. In older mice that already exhibited Lafora bodies, Gys1-ASO inhibited further accumulation, markedly preventing large Lafora bodies characteristic of advanced disease. Inhibition of Lafora body formation was associated with prevention of astrogliosis and strong trends towards correction of dysregulated expression of disease immune and neuroinflammatory markers. Lafora disease manifests gradually in previously healthy teenagers. Our work provides proof of principle that an antisense oligonucleotide targeting the GYS1 mRNA could prevent, and halt progression of, this catastrophic epilepsy.

scholarly journals Storage and Utilization of Glycogen by Mouse Liver during Adaptation to Nutritional Changes Are GLP-1 and PASK Dependent

Nutrients ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 2552
Author(s):  
Ana Pérez-García ◽  
Verónica Hurtado-Carneiro ◽  
Carmen Herrero-De-Dios ◽  
Pilar Dongil ◽  
José Enrique García-Mauriño ◽  
...  
Keyword(s):  
Nutritional Status ◽  
Energy Homeostasis ◽  
Glucose Transporter ◽  
Glycogen Synthase ◽  
Regulatory Element ◽  
Glycogen Synthesis ◽  
Glycogen Metabolism ◽  
Hepatic Glycogen ◽  
Glycogen Accumulation ◽  
Glucose Transporter 2

Glucagon-like peptide 1 (GLP-1) and PAS kinase (PASK) control glucose and energy homeostasis according to nutritional status. Thus, both glucose availability and GLP-1 lead to hepatic glycogen synthesis or degradation. We used a murine model to discover whether PASK mediates the effect of exendin-4 (GLP-1 analogue) in the adaptation of hepatic glycogen metabolism to nutritional status. The results indicate that both exendin-4 and fasting block the Pask expression, and PASK deficiency disrupts the physiological levels of blood GLP1 and the expression of hepatic GLP1 receptors after fasting. Under a non-fasted state, exendin-4 treatment blocks AKT activation, whereby Glucokinase and Sterol Regulatory Element-Binding Protein-1c (Srebp1c) expressions were inhibited. Furthermore, the expression of certain lipogenic genes was impaired, while increasing Glucose Transporter 2 (GLUT2) and Glycogen Synthase (GYS). Moreover, exendin-4 treatment under fasted conditions avoided Glucose 6-Phosphatase (G6pase) expression, while maintaining high GYS and its activation state. These results lead to an abnormal glycogen accumulation in the liver under fasting, both in PASK-deficient mice and in exendin-4 treated wild-type mice. In short, exendin-4 and PASK both regulate glucose transport and glycogen storage, and some of the exendin-4 effects could therefore be due to the blocking of the Pask expression.

scholarly journals Interrelationship of glycogen metabolism and lactose synthesis in mammary epithelial cells of mice

1980 ◽  
Vol 192 (2) ◽  
pp. 695-702 ◽  
Author(s):  
J T Emerman ◽  
J C Bartley ◽  
M J Bissell
Keyword(s):  
Epithelial Cells ◽  
Mammary Epithelial Cells ◽  
Glycogen Synthase ◽  
Glycogen Synthesis ◽  
Late Pregnancy ◽  
Glycogen Metabolism ◽  
Mouse Mammary Gland ◽  
Mammary Epithelial ◽  
Glycogen Accumulation ◽  
Lactose Synthesis

Glycogen metabolism in mammary epithelial cells was investigated (i) by studying the conversion of glucose into glycogen and other cellular products in these cells from virgin, pregnant and lactating mice and (ii) by assaying the enzymes directly involved with glycogen metabolism. We find that: (1) mammary epithelial cells synthesized glycogen at rates up to over 60% that of the whole gland; (2) the rate of this synthesis was modulated greatly during the reproductive cycle, reaching a peak in late pregnancy and decreasing rapidly at parturition, when abundant synthesis of lactose was initiated; (3) glycogen synthase and phosphorylase activities reflected this modulation in glycogen metabolism; (4) lactose synthesis reached a plateau during late pregnancy, even though lactose synthase is reported to increase in the mouse mammary gland at this time. We propose that glycogen synthesis restricts lactose synthesis during late pregnancy by competing successfully for the shared UDP-glucose pool. The physiological advantage of glycogen accumulation during late pregnancy is discussed.

scholarly journals Generation and characterization of a laforin nanobody inhibitor

2021 ◽  
Author(s):  
Zoe R. Simmons ◽  
Savita Sharma ◽  
Jeremiah Wayne ◽  
Sheng Li ◽  
Craig W. Vander Kooi ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Glycogen Metabolism ◽  
Childhood Epilepsy ◽  
Hydrogen Deuterium Exchange ◽  
Lafora Disease ◽  
Gene Encoding ◽  
Lafora Bodies ◽  
Hydrogen Deuterium

AbstractMutations in the gene encoding the glycogen phosphatase laforin result in the fatal childhood epilepsy Lafora disease (LD). A cellular hallmark of LD is cytoplasmic, hyper-phosphorylated, glycogen-like aggregates called Lafora bodies (LBs) that form in nearly all tissues and drive disease progression. Additional tools are needed to define the cellular function of laforin, understand the pathological role of laforin in LD, and determine the role of glycogen phosphate in glycogen metabolism. We present the generation and characterization of laforin nanobodies. We identify multiple classes of specific laforin-binding nanobodies and determine their binding epitopes using hydrogen deuterium exchange (HDX) mass spectrometry. Further, one family of nanobodies is identified that serves as an inhibitor of laforin catalytic activity. The laforin nanobodies are an important set of tools that open new avenues to define unresolved questions.

scholarly journals Lafora Disease: A Review of Molecular Mechanisms and Pathology

2018 ◽  
Vol 49 (06) ◽  
pp. 357-362 ◽  
Author(s):  
Brandy Verhalen ◽  
Susan Arnold ◽  
Berge Minassian
Keyword(s):  
Ubiquitin Ligase ◽  
Molecular Mechanisms ◽  
Neurodegenerative Disorder ◽  
Vegetative State ◽  
Glycogen Synthesis ◽  
Loss Of Function ◽  
Lafora Disease ◽  
Lafora Bodies ◽  
Progressive Myoclonus Epilepsy ◽  
Myoclonus Epilepsy

AbstractLafora's disease is a neurodegenerative disorder caused by recessive loss-of-function mutations in the EPM2A (laforin glycogen phosphatase) or EPM2B (malin E3 ubiquitin ligase) genes. Neuropathology is characterized by malformed precipitated glycogen aggregates termed Lafora bodies. Asymptomatic until adolescence, patients undergo first insidious then rapid progressive myoclonus epilepsy toward a vegetative state and death within a decade. Laforin and malin interact to regulate glycogen phosphorylation and chain length pattern, the latter critical to glycogen's solubility. Significant gaps remain in precise mechanistic understanding. However, demonstration that partial reduction in brain glycogen synthesis near-completely prevents the disease in its genetic animal models opens a direct present path to therapy.

scholarly journals Glycogen and its metabolism: some new developments and old themes

2012 ◽  
Vol 441 (3) ◽  
pp. 763-787 ◽  
Author(s):  
Peter J. Roach ◽  
Anna A. Depaoli-Roach ◽  
Thomas D. Hurley ◽  
Vincent S. Tagliabracci
Keyword(s):  
Glycogen Synthase ◽  
Three Dimensional ◽  
Glycogen Metabolism ◽  
Glycogen Storage ◽  
Genetically Engineered ◽  
Relative Importance ◽  
Lafora Disease ◽  
New Developments ◽  
Glycogen Accumulation ◽  
Genetically Engineered Mice

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.

Role of Akt2 in contraction-stimulated cell signaling and glucose uptake in skeletal muscle

2006 ◽  
Vol 291 (5) ◽  
pp. E1031-E1037 ◽  
Author(s):  
Kei Sakamoto ◽  
David E. Arnolds ◽  
Nobuharu Fujii ◽  
Henning F. Kramer ◽  
Michael F. Hirshman ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Glucose Uptake ◽  
Intracellular Signaling ◽  
Mammalian Cells ◽  
Glycogen Synthase ◽  
Glycogen Synthesis ◽  
Glycogen Metabolism ◽  
Serine Threonine Kinase ◽  
Gsk 3Β

The serine/threonine kinase Akt/PKB plays diverse roles in cells, and genetic studies have indicated distinct roles for the three Akt isoforms expressed in mammalian cells and tissues. Akt2 is a key signaling intermediate for insulin-stimulated glucose uptake and glycogen synthesis in skeletal muscle. Akt2 has also been shown to be activated by exercise and muscle contraction in both rodents and humans. In this study, we used Akt2 knockout mice to explore the role of Akt2 in exercise-stimulated glucose uptake and glycogen synthesis as well as intracellular signaling pathways that regulate glycogen metabolism in skeletal muscle. We found that Akt2 deficiency does not affect basal or exercise-stimulated glucose uptake or intracellular glycogen content in the soleus muscle. In addition, lack of Akt2 did not result in alterations in basal Akt Thr308 or basal and contraction-stimulated glycogen synthase kinase-3β (GSK-3β) Ser9 phosphorylation, glycogen synthase phosphorylation, or glycogen synthase activity. In contrast, in situ contraction failed to elicit normal increases in Akt T-loop Thr308 phosphorylation and GSK-3α Ser21 phosphorylation in tibialis anterior muscles from Akt2-deficient animals. Our data establish a key role for Akt2 in the regulation of GSK-3α Ser21 phosphorylation with contraction and add genetic evidence to support the separation of the intracellular pathways regulated by insulin and exercise that converge on glucose uptake and glycogen synthesis in skeletal muscle.

scholarly journals Pho85p, a cyclin-dependent protein kinase, and the Snf1p protein kinase act antagonistically to control glycogen accumulation in Saccharomyces cerevisiae.

1996 ◽  
Vol 16 (8) ◽  
pp. 4357-4365 ◽  
Author(s):  
D Huang ◽  
I Farkas ◽  
P J Roach
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Protein Kinase ◽  
Kinase Activity ◽  
Glycogen Synthase ◽  
Glycogen Synthesis ◽  
Mutant Gene ◽  
Glycogen Synthase Kinase ◽  
Partial Purification ◽  
Glycogen Accumulation ◽  
Dependent Protein

In Saccharomyces cerevisiae, nutrient levels control multiple cellular processes. Cells lacking the SNF1 gene cannot express glucose-repressible genes and do not accumulate the storage polysaccharide glycogen. The impaired glycogen synthesis is due to maintenance of glycogen synthase in a hyperphosphorylated, inactive state. In a screen for second site suppressors of the glycogen storage defect of snf1 cells, we identified a mutant gene that restored glycogen accumulation and which was allelic with PHO85, which encodes a member of the cyclin-dependent kinase family. In cells with disrupted PHO85 genes, we observed hyperaccumulation of glycogen, activation of glycogen synthase, and impaired glycogen synthase kinase activity. In snf1 cells, glycogen synthase kinase activity was elevated. Partial purification of glycogen synthase kinase activity from yeast extracts resulted in the separation of two fractions by phenyl-Sepharose chromatography, both of which phosphorylated and inactivated glycogen synthase. The activity of one of these, GPK2, was inhibited by olomoucine, which potently inhibits cyclin-dependent protein kinases, and contained an approximately 36-kDa species that reacted with antibodies to Pho85p. Analysis of Ser-to-Ala mutations at the three potential Gsy2p phosphorylation sites in pho85 cells implicated Ser-654 and/or Thr-667 in PHO85 control of glycogen synthase. We propose that Pho85p is a physiological glycogen synthase kinase, possibly acting downstream of Snf1p.

Multiple metabolic effects of CGRP in conscious rats: role of glycogen synthase and phosphorylase

1993 ◽  
Vol 264 (1) ◽  
pp. E1-E10 ◽  
Author(s):  
L. Rossetti ◽  
S. Farrace ◽  
S. B. Choi ◽  
A. Giaccari ◽  
L. Sloan ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Glycogen Synthase ◽  
Hepatic Glucose Production ◽  
Glycogen Synthesis ◽  
Plasma Concentrations ◽  
Glucose Production ◽  
Glucose Disposal ◽  
Hepatic Glucose ◽  
Intracellular Glucose

Calcitonin gene-related peptide (CGRP) is a neuropeptide that is released at the neuromuscular junction in response to nerve excitation. To examine the relationship between plasma CGRP concentration and intracellular glucose metabolism in conscious rats, we performed insulin (22 pmol.kg-1.min-1) clamp studies combined with the infusion of 0, 20, 50, 100, 200, and 500 pmol.kg-1.min-1 CGRP (plasma concentrations ranging from 2 x 10(-11) to 5 x 10(-9) M). CGRP antagonized insulin's suppression of hepatic glucose production at plasma concentrations (approximately 10(-10) M) that are only two- to fivefold its basal portal concentration. Insulin-mediated glucose disposal was decreased by 20-32% when CGRP was infused at 50 pmol.kg-1.min-1 (plasma concentration 3 x 10(-10) M) or more. The impairment in insulin-stimulated glycogen synthesis in skeletal muscle accounted for all of the CGRP-induced decrease in glucose disposal, while whole body glycolysis was increased despite the reduction in total glucose uptake. The muscle glucose 6-phosphate concentration progressively increased during the CGRP infusions. CGRP inhibited insulin-stimulated glycogen synthase in skeletal muscle with a 50% effective dose of 1.9 +/- 0.36 x 10(-10) M. This effect on glycogen synthase was due to a reduction in enzyme affinity for UDP-glucose, with no changes in the maximal velocity. In vitro CGRP stimulated both hepatic and skeletal muscle adenylate cyclase in a dose-dependent manner. These data suggest that 1) CGRP is a potent antagonist of insulin at the level of muscle glycogen synthesis and hepatic glucose production; 2) inhibition of glycogen synthase is its major biochemical action in skeletal muscle; and 3) these effects are present at concentrations of the peptide that may be in the physiological range for portal vein and skeletal muscle. These data underscore the potential role of CGRP in the physiological modulation of intracellular glucose metabolism.

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