Abnormal glycogen chain length pattern, not hyperphosphorylation, is critical in Lafora disease

Abstract Lafora disease (LD) is a fatal progressive epilepsy essentially caused by loss‐of‐function mutations in the glycogen phosphatase laforin or the ubiquitin E3 ligase malin. Glycogen in LD is hyperphosphorylated and poorly hydrosoluble. It precipitates and accumulates into neurotoxic Lafora bo...

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Main Authors: Felix Nitschke, Mitchell A Sullivan, Peixiang Wang, Xiaochu Zhao, Erin E Chown, Ami M Perri, Lori Israelian, Lucia Juana‐López, Paola Bovolenta, Santiago Rodríguez de Córdoba, Martin Steup, Berge A Minassian
Format: Article
Language:English
Published: Springer Nature 2017-05-01
Series:EMBO Molecular Medicine
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Online Access:https://doi.org/10.15252/emmm.201707608
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author Felix Nitschke
Mitchell A Sullivan
Peixiang Wang
Xiaochu Zhao
Erin E Chown
Ami M Perri
Lori Israelian
Lucia Juana‐López
Paola Bovolenta
Santiago Rodríguez de Córdoba
Martin Steup
Berge A Minassian
author_facet Felix Nitschke
Mitchell A Sullivan
Peixiang Wang
Xiaochu Zhao
Erin E Chown
Ami M Perri
Lori Israelian
Lucia Juana‐López
Paola Bovolenta
Santiago Rodríguez de Córdoba
Martin Steup
Berge A Minassian
author_sort Felix Nitschke
collection DOAJ
description Abstract Lafora disease (LD) is a fatal progressive epilepsy essentially caused by loss‐of‐function mutations in the glycogen phosphatase laforin or the ubiquitin E3 ligase malin. Glycogen in LD is hyperphosphorylated and poorly hydrosoluble. It precipitates and accumulates into neurotoxic Lafora bodies (LBs). The leading LD hypothesis that hyperphosphorylation causes the insolubility was recently challenged by the observation that phosphatase‐inactive laforin rescues the laforin‐deficient LD mouse model, apparently through correction of a general autophagy impairment. We were for the first time able to quantify brain glycogen phosphate. We also measured glycogen content and chain lengths, LBs, and autophagy markers in several laforin‐ or malin‐deficient mouse lines expressing phosphatase‐inactive laforin. We find that: (i) in laforin‐deficient mice, phosphatase‐inactive laforin corrects glycogen chain lengths, and not hyperphosphorylation, which leads to correction of glycogen amounts and prevention of LBs; (ii) in malin‐deficient mice, phosphatase‐inactive laforin confers no correction; (iii) general impairment of autophagy is not necessary in LD. We conclude that laforin's principle function is to control glycogen chain lengths, in a malin‐dependent fashion, and that loss of this control underlies LD.
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spelling doaj-art-a2b1331cf25e4a71adbb2ac75bba0a1b2025-08-20T04:02:56ZengSpringer NatureEMBO Molecular Medicine1757-46761757-46842017-05-019790691710.15252/emmm.201707608Abnormal glycogen chain length pattern, not hyperphosphorylation, is critical in Lafora diseaseFelix Nitschke0Mitchell A Sullivan1Peixiang Wang2Xiaochu Zhao3Erin E Chown4Ami M Perri5Lori Israelian6Lucia Juana‐López7Paola Bovolenta8Santiago Rodríguez de Córdoba9Martin Steup10Berge A Minassian11Program in Genetics and Genome Biology, The Hospital for Sick Children Research InstituteProgram in Genetics and Genome Biology, The Hospital for Sick Children Research InstituteProgram in Genetics and Genome Biology, The Hospital for Sick Children Research InstituteProgram in Genetics and Genome Biology, The Hospital for Sick Children Research InstituteProgram in Genetics and Genome Biology, The Hospital for Sick Children Research InstituteProgram in Genetics and Genome Biology, The Hospital for Sick Children Research InstituteProgram in Genetics and Genome Biology, The Hospital for Sick Children Research InstituteCentro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas and Ciber de Enfermedades RarasCentro de Biología Molecular Severo Ochoa, CSIC‐UAM and Ciber de Enfermedades Raras, Universidad Autónoma de MadridCentro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas and Ciber de Enfermedades RarasProgram in Genetics and Genome Biology, The Hospital for Sick Children Research InstituteProgram in Genetics and Genome Biology, The Hospital for Sick Children Research InstituteAbstract Lafora disease (LD) is a fatal progressive epilepsy essentially caused by loss‐of‐function mutations in the glycogen phosphatase laforin or the ubiquitin E3 ligase malin. Glycogen in LD is hyperphosphorylated and poorly hydrosoluble. It precipitates and accumulates into neurotoxic Lafora bodies (LBs). The leading LD hypothesis that hyperphosphorylation causes the insolubility was recently challenged by the observation that phosphatase‐inactive laforin rescues the laforin‐deficient LD mouse model, apparently through correction of a general autophagy impairment. We were for the first time able to quantify brain glycogen phosphate. We also measured glycogen content and chain lengths, LBs, and autophagy markers in several laforin‐ or malin‐deficient mouse lines expressing phosphatase‐inactive laforin. We find that: (i) in laforin‐deficient mice, phosphatase‐inactive laforin corrects glycogen chain lengths, and not hyperphosphorylation, which leads to correction of glycogen amounts and prevention of LBs; (ii) in malin‐deficient mice, phosphatase‐inactive laforin confers no correction; (iii) general impairment of autophagy is not necessary in LD. We conclude that laforin's principle function is to control glycogen chain lengths, in a malin‐dependent fashion, and that loss of this control underlies LD.https://doi.org/10.15252/emmm.201707608glycogen chain lengthglycogen phosphorylationLafora diseaselaforinmalin
spellingShingle Felix Nitschke
Mitchell A Sullivan
Peixiang Wang
Xiaochu Zhao
Erin E Chown
Ami M Perri
Lori Israelian
Lucia Juana‐López
Paola Bovolenta
Santiago Rodríguez de Córdoba
Martin Steup
Berge A Minassian
Abnormal glycogen chain length pattern, not hyperphosphorylation, is critical in Lafora disease
EMBO Molecular Medicine
glycogen chain length
glycogen phosphorylation
Lafora disease
laforin
malin
title Abnormal glycogen chain length pattern, not hyperphosphorylation, is critical in Lafora disease
title_full Abnormal glycogen chain length pattern, not hyperphosphorylation, is critical in Lafora disease
title_fullStr Abnormal glycogen chain length pattern, not hyperphosphorylation, is critical in Lafora disease
title_full_unstemmed Abnormal glycogen chain length pattern, not hyperphosphorylation, is critical in Lafora disease
title_short Abnormal glycogen chain length pattern, not hyperphosphorylation, is critical in Lafora disease
title_sort abnormal glycogen chain length pattern not hyperphosphorylation is critical in lafora disease
topic glycogen chain length
glycogen phosphorylation
Lafora disease
laforin
malin
url https://doi.org/10.15252/emmm.201707608
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