Most cited article - PubMed ID 31847543
2-Hydroxyglutarate in Cancer Cells
Redox signaling from mitochondria (mt) to the cytosol and plasma membrane (PM) has been scarcely reported, such as in the case of hypoxic cell adaptation or (2-oxo-) 2-keto-isocaproate (KIC) β-like-oxidation stimulating insulin secretion in pancreatic β-cells. Mutual redox state influence between mitochondrial major compartments, the matrix and the intracristal space, and the cytosol is therefore derived theoretically in this article to predict possible conditions, when mt-to-cytosol and mt-to-PM signals may occur, as well as conditions in which the cytosolic redox signaling is not overwhelmed by the mitochondrial antioxidant capacity. Possible peroxiredoxin 3 participation in mt-to-cytosol redox signaling is discussed, as well as another specific case, whereby mitochondrial superoxide release is diminished, whereas the matrix MnSOD is activated. As a result, the enhanced conversion to H2O2 allows H2O2 diffusion into the cytosol, where it could be a predominant component of the H2O2 release. In both of these ways, mt-to-cytosol and mt-to-PM signals may be realized. Finally, the use of redox-sensitive probes is discussed, which disturb redox equilibria, and hence add a surplus redox-buffering to the compartment, where they are localized. Specifically, when attempts to quantify net H2O2 fluxes are to be made, this should be taken into account.
Mitochondrial production of 2-hydroxyglutarate (2HG) can be catalyzed by wild-type isocitrate dehydrogenase 2 (IDH2) and alcohol dehydrogenase, iron-containing 1 (ADHFE1). We investigated whether biochemical background and substrate concentration in breast cancer cells promote 2HG production. To estimate its role in 2HG production, we quantified 2HG levels and its enantiomers in breast cancer cells using analytical approaches for metabolomics. By manipulation of mitochondrial substrate fluxes using genetic and pharmacological approaches, we demonstrated the existence of active competition between 2HG producing enzymes, i.e., IDH2 and ADHFE1. Moreover, we showed that distinct fractions of IDH2 enzyme molecules operate in distinct oxido-reductive modes, providing NADPH and producing 2HG simultaneously. We have also detected 2HG release in the urine of breast cancer patients undergoing adjuvant therapy and detected a correlation with stages of breast carcinoma development. In summary, we provide a background for vital mitochondrial production of 2HG in breast cancer cells with outcomes towards cancer biology and possible future diagnosis of breast carcinoma.
- Keywords
- 2HG, IDH2, breast carcinoma,
- Publication type
- Journal Article MeSH
Wild type mitochondrial isocitrate dehydrogenase (IDH2) was previously reported to produce oncometabolite 2-hydroxyglutarate (2HG). Besides, mitochondrial deacetylase SIRT3 has been shown to regulate the oxidative function of IDH2. However, regulation of 2HG formation by SIRT3-mediated deacetylation was not investigated yet. We aimed to study mitochondrial IDH2 function in response to acetylation and deacetylation, and focus specifically on 2HG production by IDH2. We used acetylation surrogate mutant of IDH2 K413Q and assayed enzyme kinetics of oxidative decarboxylation of isocitrate, 2HG production by the enzyme, and 2HG production in cells. The purified IDH2 K413Q exhibited lower oxidative reaction rates than IDH2 WT. 2HG production by IDH2 K413Q was largely diminished at the enzymatic and cellular level, and knockdown of SIRT3 also inhibited 2HG production by IDH2. Contrary, the expression of putative mitochondrial acetylase GCN5L likely does not target IDH2. Using mass spectroscopy, we further identified lysine residues within IDH2, which are the substrates of SIRT3. In summary, we demonstrate that 2HG levels arise from non-mutant IDH2 reductive function and decrease with increasing acetylation level. The newly identified lysine residues might apply in regulation of IDH2 function in response to metabolic perturbations occurring in cancer cells, such as glucose-free conditions.
- MeSH
- Acetylation MeSH
- Glutarates metabolism MeSH
- Isocitrate Dehydrogenase genetics metabolism MeSH
- Isocitrates chemistry MeSH
- Humans MeSH
- Mitochondria metabolism MeSH
- Cell Line, Tumor MeSH
- NADP metabolism MeSH
- Oxidation-Reduction MeSH
- Nerve Tissue Proteins metabolism MeSH
- Sirtuin 3 metabolism MeSH
- Gene Silencing MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Names of Substances
- alpha-hydroxyglutarate MeSH Browser
- BLOC1S1 protein, human MeSH Browser
- Glutarates MeSH
- IDH2 protein, human MeSH Browser
- Isocitrate Dehydrogenase MeSH
- Isocitrates MeSH
- isocitric acid MeSH Browser
- NADP MeSH
- Nerve Tissue Proteins MeSH
- SIRT3 protein, human MeSH Browser
- Sirtuin 3 MeSH
Progress in mass spectroscopy of posttranslational oxidative modifications has enabled researchers to experimentally verify the concept of redox signaling. We focus here on redox signaling originating from mitochondria under physiological situations, discussing mechanisms of transient redox burst in mitochondria, as well as the possible ways to transfer such redox signals to specific extramitochondrial targets. A role of peroxiredoxins is described which enables redox relay to other targets. Examples of mitochondrial redox signaling are discussed: initiation of hypoxia-inducible factor (HIF) responses; retrograde redox signaling to PGC1α during exercise in skeletal muscle; redox signaling in innate immune cells; redox stimulation of insulin secretion, and other physiological situations.
- Keywords
- H2O2 diffusion, HIF, Redox signaling from mitochondria, mitochondrial superoxide formation, peroxiredoxins, redox-regulation of kinases,
- MeSH
- Insulin-Secreting Cells metabolism MeSH
- Hypoxia metabolism MeSH
- Immunity physiology MeSH
- Muscle, Skeletal metabolism MeSH
- Mitochondria metabolism MeSH
- Oxidation-Reduction MeSH
- Hydrogen Peroxide metabolism MeSH
- Peroxiredoxins MeSH
- Protein Processing, Post-Translational MeSH
- Reactive Oxygen Species metabolism MeSH
- Signal Transduction physiology MeSH
- Superoxides metabolism MeSH
- Publication type
- Journal Article MeSH
- Review MeSH
- Names of Substances
- Hydrogen Peroxide MeSH
- Peroxiredoxins MeSH
- Reactive Oxygen Species MeSH
- Superoxides MeSH
