Targeting Pathogenic Lafora Bodies in Lafora Disease Using an Antibody-Enzyme Fusion Notes/Citation Information To be published in Cell Metabolism.

Glycogen is the major mammalian glucose storage cache and is critical for energy homeostasis. Glycogen synthesis in neurons must be tightly controlled, due to neuronal sensitivity to perturbations in glycogen metabolism. Lafora disease (LD) is a fatal, congenital, neurodegenerative epilepsy. Mutations in the gene encoding the glycogen phosphatase laforin result in hyperphosphorylated glycogen that forms water‐insoluble inclusions called Lafora bodies (LBs). LBs induce neuronal apoptosis and are the causative agent of LD. The mechanism of glycogen dephosphorylation by laforin and dysfunction in LD is unknown. We report the crystal structure of laforin bound to phosphoglucan product revealing its unique integrated tertiary and quaternary structure. Structure‐guided mutagenesis combined with biophysical and biochemical analyses reveal the basis for normal function of laforin in glycogen metabolism. Analyses of LD patient mutations define the mechanism by which subsets of mutations disrupt laforin function. These data provide fundamental insights connecting glycogen metabolism to neurodegenerative disease.

Brain glycogen is mainly stored in astrocytes. However, recent studies both in vitro and in vivo indicate that glycogen also plays important roles in neurons. By conditional deletion of glycogen synthase (GYS1), we previously developed a mouse model entirely devoid of glycogen in the central nervous system (GYS1 Nestin-KO ). These mice displayed altered electrophysiological properties in the hippocampus and increased susceptibility to kainateinduced seizures. To understand which of these functions is related to astrocytic glycogen, in the present study we generated a mouse model in which glycogen synthesis is eliminated specifically in astrocytes (GYS1 Gfap-KO ). Electrophysiological recordings of awake behaving mice revealed alterations in input/output curves and impaired long-term potentiation, similar, but to a lesser extent, to those obtained with GYS1 Nestin-KO mice. Surprisingly, GYS1 Gfap-KO mice displayed no change in susceptibility to kainate-induced seizures as determined by fEPSP recordings and video monitoring. These results confirm the importance of astrocytic glycogen in synaptic plasticity.

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In the original publication the sentence below Abstract section incorrectly states that ''SEX4 contains a chloroplast targeting peptide, dual specificity phosphatase (DSP) domain, a CBM45, and a carboxy-terminal motif''.The correct sentence should read as below: SEX4 contains a chloroplast targeting peptide, dual specificity phosphatase (DSP) domain, a CBM48, and a carboxy-terminal motif.The online version of the original article can be found under

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