• Mitochondrial redox adaptations enable alternative aspartate synthesis in SDH-deficient cells.

Mitochondrial redox adaptations enable alternative aspartate synthesis in SDH-deficient cells.

eLife (2023-03-09)
Madeleine L Hart, Evan Quon, Anna-Lena B G Vigil, Ian A Engstrom, Oliver J Newsom, Kristian Davidsen, Pia Hoellerbauer, Samantha M Carlisle, Lucas B Sullivan

The oxidative tricarboxylic acid (TCA) cycle is a central mitochondrial pathway integrating catabolic conversions of NAD +to NADH and anabolic production of aspartate, a key amino acid for cell proliferation. Several TCA cycle components are implicated in tumorigenesis, including loss-of-function mutations in subunits of succinate dehydrogenase (SDH), also known as complex II of the electron transport chain (ETC), but mechanistic understanding of how proliferating cells tolerate the metabolic defects of SDH loss is still lacking. Here, we identify that SDH supports human cell proliferation through aspartate synthesis but, unlike other ETC impairments, the effects of SDH inhibition are not ameliorated by electron acceptor supplementation. Interestingly, we find aspartate production and cell proliferation are restored to SDH-impaired cells by concomitant inhibition of ETC complex I (CI). We determine that the benefits of CI inhibition in this context depend on decreasing mitochondrial NAD+/NADH, which drives SDH-independent aspartate production through pyruvate carboxylation and reductive carboxylation of glutamine. We also find that genetic loss or restoration of SDH selects for cells with concordant CI activity, establishing distinct modalities of mitochondrial metabolism for maintaining aspartate synthesis. These data therefore identify a metabolically beneficial mechanism for CI loss in proliferating cells and reveal how compartmentalized redox changes can impact cellular fitness.

Product Number
Product Description

Oligomycin, A mixture of A, B, and C isomers.
G 418 disulfate salt, powder, BioReagent, suitable for cell culture
Monoclonal ANTI-FLAG® M2 antibody produced in mouse, 1 mg/mL, clone M2, affinity isolated antibody, buffered aqueous solution (50% glycerol, 10 mM sodium phosphate, and 150 mM NaCl, pH 7.4)
Fetal Bovine Serum, USA origin, Dialyzed by ultrafiltration against 0.15 M NaCl, sterile-filtered, suitable for cell culture
Antimycin A from Streptomyces sp.
Rotenone, ≥95%
Anti-α-Tubulin antibody, Mouse monoclonal, clone DM1A, purified from hybridoma cell culture
Anti-Vinculin antibody, Mouse monoclonal, clone VIN-11-5, purified from hybridoma cell culture