title: 2-hydroxyglutarate production, but not dominant negative function, is conferred by glioma-derived NADP-dependent isocitrate dehydrogenase mutations.
abstract: BACKGROUND
  Gliomas frequently contain mutations in the cytoplasmic NADP(+)-dependent isocitrate dehydrogenase (IDH1) or the mitochondrial NADP(+)-dependent isocitrate dehydrogenase (IDH2). Several different amino acid substitutions recur at either IDH1 R132 or IDH2 R172 in glioma patients. Genetic evidence indicates that these mutations share a common gain of function, but it is unclear whether the shared function is dominant negative activity, neomorphic production of (R)-2-hydroxyglutarate (2HG), or both.
  
  
  RESULTS
  We show by coprecipitation that five cancer-derived IDH1 R132 mutants bind IDH1-WT but that three cancer-derived IDH2 R172 mutants exert minimal binding to IDH2-WT. None of the mutants dominant-negatively lower isocitrate dehydrogenase activity at physiological (40 µM) isocitrate concentrations in mammalian cell lysates. In contrast to this, all of these mutants confer 10- to 100-fold higher 2HG production to cells, and glioma tissues containing IDH1 R132 or IDH2 R172 mutations contain high levels of 2HG compared to glioma tissues without IDH mutations (54.4 vs. 0.1 mg 2HG/g protein).
  
  
  CONCLUSIONS
  Binding to, or dominant inhibition of, WT IDH1 or IDH2 is not a shared feature of the IDH1 and IDH2 mutations, and thus is not likely to be important in cancer. The fact that the gain of the enzymatic activity to produce 2HG is a shared feature of the IDH1 and IDH2 mutations suggests that this is an important function for these mutants in driving cancer pathogenesis.
authors.affiliation: The Preston Robert Tisch Brain Tumor Center at Duke, Pediatric Brain Tumor Foundation Institute, and Department of Pathology, Duke University Medical Center, Durham, North Carolina, United States of America.
authors.forename: Genglin
authors.initials: G
authors.lastname: Jin
authors.forename: Zachary J
authors.initials: ZJ
authors.lastname: Reitman
authors.forename: Ivan
authors.initials: I
authors.lastname: Spasojevic
authors.forename: Ines
authors.initials: I
authors.lastname: Batinic-Haberle
authors.forename: Jian
authors.initials: J
authors.lastname: Yang
authors.forename: Oleg
authors.initials: O
authors.lastname: Schmidt-Kittler
authors.forename: Darell D
authors.initials: DD
authors.lastname: Bigner
authors.forename: Hai
authors.initials: H
authors.lastname: Yan
mesh_terms: D001667:Binding, Competitive / Q000235:genetics / Q000502:physiology; D001932:Brain Neoplasms / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism; D002478:Cells, Cultured; D015536:Down-Regulation / Q000235:genetics / Q000502:physiology; D004789:Enzyme Activation / Q000235:genetics; D005799:Genes, Dominant / Q000502:physiology; D005910:Glioma / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism; D005977:Glutarates / Q000378:metabolism*; D006801:Humans; D007521:Isocitrate Dehydrogenase / Q000235:genetics* / Q000378:metabolism / Q000502:physiology*; D020125:Mutation, Missense / Q000502:physiology
chemical_list: D005977:Glutarates; C019417:alpha-hydroxyglutarate; C538784:IDH2 protein, human; D007521:Isocitrate Dehydrogenase; C039355:isocitrate dehydrogenase (NADP+); C543588:IDH1 protein, human