title: Targeted disruption of the Epm2a gene causes formation of Lafora inclusion bodies, neurodegeneration, ataxia, myoclonus epilepsy and impaired behavioral response in mice.
abstract: Mutations in the EPM2A gene encoding a dual-specificity phosphatase (laforin) cause Lafora disease (LD), a progressive and invariably fatal epilepsy with periodic acid-Schiff-positive (PAS+) cytoplasmic inclusions (Lafora bodies) in the central nervous system. To study the pathology of LD and the functions of laforin, we disrupted the Epm2a gene in mice. At two months of age, homozygous null mutants developed widespread degeneration of neurons, most of which occurred in the absence of Lafora bodies. Dying neurons characteristically exhibit swelling in the endoplasmic reticulum, Golgi networks and mitochondria in the absence of apoptotic bodies or fragmentation of DNA. As Lafora bodies become more prominent at 4-12 months, organelles and nuclei are disrupted. The Lafora bodies, present both in neuronal and non-neural tissues, are positive for ubiquitin and advanced glycation end-products only in neurons, suggesting different pathological consequence for Lafora inclusions in neuronal tissues. Neuronal degeneration and Lafora inclusion bodies predate the onset of impaired behavioral responses, ataxia, spontaneous myoclonic seizures and EEG epileptiform activity. Our results suggest that LD is a primary neurodegenerative disorder that may utilize a non-apoptotic mechanism of cell death.
authors.affiliation: Laboratory for Neurogenetics, RIKEN Brain Science Institute, Wako-shi, Saitama, Japan.
authors.forename: Subramaniam
authors.initials: S
authors.lastname: Ganesh
authors.forename: Antonio V
authors.initials: AV
authors.lastname: Delgado-Escueta
authors.forename: Toshiro
authors.initials: T
authors.lastname: Sakamoto
authors.forename: Maria Rosa
authors.initials: MR
authors.lastname: Avila
authors.forename: Jesus
authors.initials: J
authors.lastname: Machado-Salas
authors.forename: Yoshinobu
authors.initials: Y
authors.lastname: Hoshii
authors.forename: Takumi
authors.initials: T
authors.lastname: Akagi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Gomi
authors.forename: Toshimitsu
authors.initials: T
authors.lastname: Suzuki
authors.forename: Kenji
authors.initials: K
authors.lastname: Amano
authors.forename: Kishan Lal
authors.initials: KL
authors.lastname: Agarwala
authors.forename: Yuki
authors.initials: Y
authors.lastname: Hasegawa
authors.forename: Dong-Sheng
authors.initials: DS
authors.lastname: Bai
authors.forename: Tokuhiro
authors.initials: T
authors.lastname: Ishihara
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Hashikawa
authors.forename: Shigeyoshi
authors.initials: S
authors.lastname: Itohara
authors.forename: Eain M
authors.initials: EM
authors.lastname: Cornford
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Niki
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Yamakawa
mesh_terms: D000818:Animals; D001259:Ataxia / Q000503:physiopathology; D001522:Behavior, Animal; D016923:Cell Death; D054637:Dual-Specificity Phosphatases; D004569:Electroencephalography; D004831:Epilepsies, Myoclonic / Q000503:physiopathology; D005260:Female; D002479:Inclusion Bodies / Q000378:metabolism; D020192:Lafora Disease / Q000235:genetics* / Q000473:pathology / Q000503:physiopathology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D016297:Mutagenesis, Site-Directed; D009474:Neurons / Q000378:metabolism / Q000648:ultrastructure; D017027:Protein Tyrosine Phosphatases / Q000172:deficiency / Q000235:genetics* / Q000502:physiology; D054558:Protein Tyrosine Phosphatases, Non-Receptor; D025801:Ubiquitin / Q000378:metabolism
chemical_list: D025801:Ubiquitin; D054637:Dual-Specificity Phosphatases; C491989:Epm2a protein, mouse; D017027:Protein Tyrosine Phosphatases; D054558:Protein Tyrosine Phosphatases, Non-Receptor