title: Mutation of ataxia-telangiectasia mutated is associated with dysfunctional glutathione homeostasis in cerebellar astroglia.
abstract: Astroglial dysfunction plays an important role in neurodegenerative diseases otherwise attributed to neuronal loss of function. Here we focus on the role of astroglia in ataxia-telangiectasia (A-T), a disease caused by mutations in the ataxia-telangiectasia mutated (ATM) gene. A hallmark of A-T pathology is progressive loss of cerebellar neurons, but the mechanisms that impact neuronal survival are unclear. We now provide a possible mechanism by which A-T astroglia affect the survival of cerebellar neurons. As astroglial functions are difficult to study in an in vivo setting, particularly in the cerebellum where these cells are intertwined with the far more numerous neurons, we conducted in vitro coculture experiments that allow for the generation and pharmacological manipulation of purified cell populations. Our analyses revealed that cerebellar astroglia isolated from Atm mutant mice show decreased expression of the cystine/glutamate exchanger subunit xCT, glutathione (GSH) reductase, and glutathione-S-transferase. We also found decreased levels of intercellular and secreted GSH in A-T astroglia. Metabolic labeling of l-cystine, the major precursor for GSH, revealed that a key component of the defect in A-T astroglia is an impaired ability to import this rate-limiting precursor for the production of GSH. This impairment resulted in suboptimal extracellular GSH supply, which in turn impaired survival of cerebellar neurons. We show that by circumventing the xCT-dependent import of L-cystine through addition of N-acetyl-L-cysteine (NAC) as an alternative cysteine source, we were able to restore GSH levels in A-T mutant astroglia providing a possible future avenue for targeted therapeutic intervention.
authors.affiliation: Department of Biomedical Genetics, University of Rochester, Rochester, New York, 14642.|Department of Pathology and Laboratory Medicine, University of Rochester, Rochester, New York, 14642.
authors.forename: Andrew
authors.initials: A
authors.lastname: Campbell
authors.affiliation: School of Pharmacy Health Sciences Center, University of Wyoming, Laramie, Wyoming, 82071.
authors.forename: Jared
authors.initials: J
authors.lastname: Bushman
authors.affiliation: Department of Biochemistry and Biophysics, University of Rochester, Rochester, New York, 14642.
authors.forename: Joshua
authors.initials: J
authors.lastname: Munger
authors.affiliation: Department of Biomedical Genetics, University of Rochester, Rochester, New York, 14642.
authors.forename: Mark
authors.initials: M
authors.lastname: Noble
authors.affiliation: Department of Biomedical Genetics, University of Rochester, Rochester, New York, 14642.
authors.forename: Christoph
authors.initials: C
authors.lastname: Pröschel
authors.affiliation: Department of Biomedical Genetics, University of Rochester, Rochester, New York, 14642.
authors.forename: Margot
authors.initials: M
authors.lastname: Mayer-Pröschel
mesh_terms: D000111:Acetylcysteine / Q000378:metabolism; D000293:Adolescent; D027182:Amino Acid Transport System y+ / Q000378:metabolism; D000818:Animals; D001253:Astrocytes / Q000378:metabolism*; D064007:Ataxia Telangiectasia Mutated Proteins / Q000235:genetics / Q000378:metabolism; D002470:Cell Survival / Q000502:physiology; D002531:Cerebellum / Q000378:metabolism*; D018920:Coculture Techniques; D003553:Cystine / Q000378:metabolism; D005110:Extracellular Space / Q000378:metabolism; D005978:Glutathione / Q000378:metabolism*; D005980:Glutathione Reductase / Q000378:metabolism; D006706:Homeostasis / Q000502:physiology*; D006801:Humans; D042541:Intracellular Space / Q000378:metabolism; D057507:Mice, 129 Strain; D008822:Mice, Transgenic; D009154:Mutation; D009474:Neurons / Q000502:physiology
chemical_list: D027182:Amino Acid Transport System y+; C492255:Slc7a11 protein, mouse; D003553:Cystine; D005980:Glutathione Reductase; D064007:Ataxia Telangiectasia Mutated Proteins; C576325:Atm protein, mouse; D005978:Glutathione; D000111:Acetylcysteine
keywords: astroglia; ataxia-telangiectasia; ataxia-telangiectasia mutated; cerebellum; glutathione; neuronal survival; xCT