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Since the discovery of mutations in isocitrate dehydrogenase 1 (IDH1) in gliomas and other tumors, significant efforts have been made to gain a deeper understanding of the consequences of this oncogenic mutation. One aspect of the neomorphic function of the IDH1 R132H enzyme that has received less attention is the perturbation of cellular redox homeostasis. Here, we describe a biosynthetic pathway exhibited by cells expressing mutant IDH1. By virtue of a change in cellular redox homeostasis, IDH1-mutated cells synthesize excess glutamine-derived proline through enhanced activity of pyrroline 5-carboxylate reductase 1 (PYCR1), coupled to NADH oxidation. Enhanced proline biosynthesis partially uncouples the electron transport chain from tricarboxylic acid (TCA) cycle activity through the maintenance of a lower NADH/NAD+ ratio and subsequent reduction in oxygen consumption. Thus, we have uncovered a mechanism by which tumor cell survival may be promoted in conditions associated with perturbed redox homeostasis, as occurs in IDH1-mutated glioma.

Original publication

DOI

10.1016/j.celrep.2018.02.084

Type

Journal article

Journal

Cell Rep

Publication Date

20/03/2018

Volume

22

Pages

3107 - 3114

Keywords

IDH1, glioma, metabolism, proline, redox, Cell Line, Tumor, Citric Acid Cycle, Gene Knockdown Techniques, Glutamine, Homeostasis, Humans, Isocitrate Dehydrogenase, Mitochondria, Mutation, Oligodendroglioma, Oxidation-Reduction, Proline, Pyrroline Carboxylate Reductases