Kinase experiment:

To assay human JHDM1A/KDM2A demethylase activity toward H3K36me2, His tagged JHDM1A is first obtained by transforming pET28a-JHDM1A into Escherichia coli BL21 and protein expression is induced by addition of 1 mM IPTG at 30℃ when cell density reaches 0.5 OD600 units. Cells are lysed by sonication and Ni-NTA agarose is used to purify His-JHDM1A fusion proteins. Histone demethylase assay is carried out by incubating 2 μg oligonucleosomes, 4 μg purified His-JHDM1A, and/or 10-50 mM D-2-HG in histone demethylation buffer [50 mM HEPES (pH 8.0), 625 μM Fe(NH4)2(SO4)2, 0.1-0.5 mM α-KG, 2 mM ascorbate] at 37℃ for 2-3 hr and the reactions are stopped by the addition of SDS loading buffer and subsequently analyzed by western blotting using anti-H3K36me2 antibody. To measure CeKDM7A demethylase activity toward H3K9me2 and H3K27me2, two synthetic dimethylated peptides H3K9me2 [ARTKQTARK (me2)STGGKA] and H3K27me2 [QLATKAARK (me2)SAPAS] are used as substrates. Demethylase assays are carried out in the presence of 10 μg enzyme, 1 μg peptide in 20 μl buffer 20 mM Tris-HCl (pH 7.5), 150 mM NaCl, 50 μM (NH4)2Fe(SO4)2, 100 μM α-KG, 2 mM Vc, 10 mM PMSF for 3 hr. The demethylation reaction mixture is desalted by passing through a C18 ZipTip. To examine the inhibitory effect of 2-HG, various concentrations of 2-HG are incubated with KDM7A briefly before adding other reaction mixtures. The samples are analyzed by a MALDI-TOF/TOF mass spectrometer[1].

Cell experiment:

U87 cells, HCT 116 IDH1(R132H/+) cells, and HEK 293 cells are seeded in 12-well plates and after overnight incubation are treated with indicated concentrations of each compound (e.g., 400 and 800 μM D-2-HG). After harvesting, cells are stained with Acridine Orange (AO) and DAPI. Cell number and viability are measured based on AO and DAPI fluorescence measured by NC3000[2].

Information here is from (R)-2-hydroxyglutarate ((R)-2HG) instead of Disodium (R)-2-Hydroxyglutarate. (R)-2HG inhibits adenosine triphosphate (ATP) synthase [1]. The IC50 value has not been found.

ATP synthase containing a rotary motor involved in energy conversion in organisms. It produces ATP from inorganic phosphate and adenosine diphosphate (ADP). It functions using the energy from a respiration- or photosynthesis-generated transmembrane proton-motive force [2].

Data showed that (R)-2HG accumulated in human cancers carrying mutant isocitrate dehydrogenase (IDH) 1 and 2 genes. In IDH1 mutant cells, the inhibition of (R)-2HG to ATP synthase was mirrored. This indicated that (R)-2HG has a growth-suppressive function. In glioblastoma cells, consistently, the inhibition of (R)-2HG to ATP synthase is sufficient for tumor cell killing and growth arrest under glucose limitation conditions, e.g., when ketone bodies are supplied for energy instead of glucose. In cells, treatment with (R)-2HG decreased the rate of ATP synthase-linked oxygen consumption [1].

The normal cellular concentration of (R)-2HG is 200 mM. At this concentration, ATP synthase is unlikely to be significantly inhibited by (R)-2HG. In glioma patients with IDH mutations, (R)-2HG accumulates to 10-100 times of normal levels, and ATP synthase would be possible to be inhibited. (R)-2HG extended the lifespan of C. elegans, in a similar way of α-KG. Data showed that 2-HG increased lifespan ATP-synthase-dependently [1].

References:
[1].  Fu X, Chin RM, Vergnes L, et al. 2-Hydroxyglutarate inhibits ATP synthase and mTOR signaling. Cell metabolism, 2015, 22(3): 508-515.
[2].  Stock D, Leslie AGW and Walker JE. Molecular architecture of the rotary motor in ATP synthase. Science, 1999, 286(5445): 1700-1705.