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Photoactivation of Mutant Isocitrate Dehydrogenase 2 Reveals Rapid Cancer-Associated Metabolic and Epigenetic Changes

Author:
Walker, Olivia S., Elsässer, Simon J., Mahesh, Mohan, Bachman, Martin, Balasubramanian, Shankar, Chin, Jason W.
Source:
Journal of the American Chemical Society 2016 v.138 no.3 pp. 718-721
ISSN:
1520-5126
Subject:
DNA, active sites, arginine, epigenetics, genetic code, isocitrate dehydrogenase, lighting, lysine, mammals, mutants, mutation, neoplasms, patients
Abstract:
Isocitrate dehydrogenase is mutated at a key active site arginine residue (Arg172 in IDH2) in many cancers, leading to the synthesis of the oncometabolite (R)-2-hydroxyglutarate (2HG). To investigate the early events following acquisition of this mutation in mammalian cells we created a photoactivatable version of IDH2(R172K), in which K172 is replaced with a photocaged lysine (PCK), via genetic code expansion. Illumination of cells expressing this mutant protein led to a rapid increase in the levels of 2HG, with 2HG levels reaching those measured in patient tumor samples, within 8 h. 2HG accumulation is closely followed by a global decrease in 5-hydroxymethylcytosine (5-hmC) in DNA, demonstrating that perturbations in epigenetic DNA base modifications are an early consequence of mutant IDH2 in cells. Our results provide a paradigm for rapidly and synchronously uncloaking diverse oncogenic mutations in live cells to reveal the sequence of events through which they may ultimately cause transformation.
Agid:
5487213