Gain of interaction of ALS-linked G93A superoxide dismutase with cytosolic malate dehydrogenase

• Main Authors: Yael Mali, Nava Zisapels
• Format: Article
• Language: English
• Published: Elsevier 2008-10-01
• Series: Neurobiology of Disease
• Subjects: SOD1; ALS; Amyotrophic Lateral Sclerosis; Malate dehydrogenase; Protein interactions; FRET
• Online Access: http://www.sciencedirect.com/science/article/pii/S0969996108001423

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.