Oncogenic IDH1 Mutations Promote Enhanced Proline Synthesis through PYCR1 to Support the Maintenance of Mitochondrial Redox Homeostasis

• DOI: 10.1016/j.celrep.2018.02.084
• Publication Date: 2018-03-21T00:23:51Z
• Authors: Kate E.R. Hollins...; Haydn Munford; Katherine L. Eales; Chiara Bardella; Chunjie Li; Cristina Escriban...; Alpesh Thakker; Yannic Nonnenmacher; Katarina Kluckova; Mark Jeeves; Robert Murren; Federica Cuozzo; Dan Ye; Giulio Laurenti; Wei Zhu; Karsten Hiller; David J. Hodson; Wei Hua; Ian P. Tomlinson; Christian Ludwig; Ying Mao; Daniel A. Tennant
• Keywords: 0303 health sciences; Proline; QH301-705.5; Research; Glutamine; Citric Acid Cycle; Oligodendroglioma; 540; Article; Isocitrate Dehydrogenase; Mitochondria; delta-1-Pyrroline-5-Carboxylate Reductase; 03 medical and health sciences; Legacy; Cell Line, Tumor; Gene Knockdown Techniques; Mutation; Homeostasis; Humans; Pyrroline Carboxylate Reductases; Biology (General); Oxidation-Reduction

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.