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  • Cancer-associated isocitrate dehydrogenase mutations inactivate NADPH-dependent reductive carboxylation.

Cancer-associated isocitrate dehydrogenase mutations inactivate NADPH-dependent reductive carboxylation.

The Journal of biological chemistry (2012-03-24)
Roberta Leonardi, Chitra Subramanian, Suzanne Jackowski, Charles O Rock
ABSTRACT

Isocitrate dehydrogenase (IDH) is a reversible enzyme that catalyzes the NADP(+)-dependent oxidative decarboxylation of isocitrate (ICT) to α-ketoglutarate (αKG) and the NADPH/CO(2)-dependent reductive carboxylation of αKG to ICT. Reductive carboxylation by IDH1 was potently inhibited by NADP(+) and, to a lesser extent, by ICT. IDH1 and IDH2 with cancer-associated mutations at the active site arginines were unable to carry out the reductive carboxylation of αKG. These mutants were also defective in ICT decarboxylation and converted αKG to 2-hydroxyglutarate using NADPH. These mutant proteins were thus defective in both of the normal reactions of IDH. Biochemical analysis of heterodimers between wild-type and mutant IDH1 subunits showed that the mutant subunit did not inactivate reductive carboxylation by the wild-type subunit. Cells expressing the mutant IDH are thus deficient in their capacity for reductive carboxylation and may be compromised in their ability to produce acetyl-CoA under hypoxia or when mitochondrial function is otherwise impaired.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
D-2-Hydroxyglutarate (D2HG) Assay Kit, sufficient for 200 fluorometric reactions