An inducible glycogen synthase-1 knockout halts but does not reverse lafora disease progression in mice

Silvia Nitschke, Erin E. Chown, Zhao Xiaochu, Shoghig Gabrielian, Sara Petkovic, Dikran R. Guisso, Ami M. Perri, Peixiang Wang, Saija Ahonen, Felix Nitschke, Berge A. Minassian

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

Malstructured glycogen accumulates over time in Lafora dis ease (LD) and precipitates into Lafora bodies (LBs), leading to neurodegeneration and intractable fatal epilepsy. Constitutive reduction of glycogen synthase-1 (GYS1) activity prevents murine LD, but the effect of GYS1 reduction later in disease course is unknown. Our goal was to knock out Gys1 in laforin (Epm2a)-deficient LD mice after disease onset to determine whether LD can be halted in midcourse, or even reversed. We generated Epm2a-deficient LD mice with tamoxifen-inducible Cre-medi ated Gys1 knockout. Tamoxifen was administered at 4 months and disease progression assessed at 12 months. We verified successful knockout at mRNA and protein levels using droplet digital PCR and Western blots. Glycogen determination and periodic acid-Schiff-diastase staining were used to analyze glycogen and LB accumulation. Immunohistochemistry using astrocytic (glial fibrillary acidic protein) and microglial (ionized calcium-binding adapter molecule 1) markers was performed to investigate neuroinflammation. In the disease-relevant organ, the brain, Gys1 mRNA levels were reduced by 85% and GYS1 protein depleted. Glycogen accumulation was halted at the 4-month level, while LB formation and neuroinflammation were signifi cantly, though incompletely, prevented. Skeletal muscle analysis confirmed that Gys1 knockout inhibits glycogen and LB accu mulation. However, tamoxifen-independent Cre recombination precluded determination of disease halting or reversal in this tissue. Our study shows that Gys1 knockdown is a powerful means to prevent LD progression, but this approach did not reduce brain glycogen or LBs to levels below those at the time of intervention. These data suggest that endogenous mechanisms to clear brain LBs are absent or, possibly, compromised in laforin deficient murine LD.

Original languageEnglish (US)
Article number100150
JournalJournal of Biological Chemistry
Volume296
DOIs
StatePublished - Jan 1 2021

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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