title: Gain of interaction of ALS-linked G93A superoxide dismutase with cytosolic malate dehydrogenase.
abstract: Protein interactions of the Amyotrophic Lateral Sclerosis (ALS)-linked copper-zinc superoxide dismutase (hSOD1) G93A mutation were studied using a fluorescence resonance energy transfer (FRET) based screening system. The FRET results confirmed by pull-down immunoprecipitation indicated "gain-of-interaction" of the G93A-hSOD1 mutant with cytosolic malate dehydrogenase (cytMDH)-a key enzyme in the malate-aspartate shuttle which is vital to neurons. Furthermore, cytMDH mRNA expression was upregulated in G93A-hSOD1 expressing cells but endogenous cytMDH enzymatic activity was not enhanced, not even with exogenously added-on enzyme. Consistent with inhibition of the malate-aspartate shuttle, G93A-hSOD1 had lower malate and higher lactate levels compared to non-induced or Wild-Type-hSOD1 expressing cells. Mitochondrial NADH/NAD+ ratio is also elevated. Malate-aspartate shuttle dysfunction may explain the damage to neurons and the vulnerability to impairments of glycolytic pathways in ALS and provide a new target for the development of potential therapies.
authors.affiliation: Department of Neurobiology, Tel Aviv University, Tel Aviv 69978, Israel.
authors.forename: Yael
authors.initials: Y
authors.lastname: Mali
authors.forename: Nava
authors.initials: N
authors.lastname: Zisapels
mesh_terms: D000690:Amyotrophic Lateral Sclerosis / Q000201:enzymology* / Q000473:pathology; D000818:Animals; D001224:Aspartic Acid / Q000378:metabolism; D002460:Cell Line; D003600:Cytosol / Q000201:enzymology* / Q000473:pathology; D006801:Humans; D008291:Malate Dehydrogenase / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D008293:Malates / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D009474:Neurons / Q000201:enzymology / Q000378:metabolism / Q000473:pathology; D013482:Superoxide Dismutase / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*
chemical_list: D008293:Malates; D001224:Aspartic Acid; C030298:malic acid; D008291:Malate Dehydrogenase; C109415:SOD1 G93A protein; D013482:Superoxide Dismutase