Octyl-α-ketoglutarate is a prolyl hydroxylases substrate which accumulates rapidly in cells with dysfunctional tricarboxylic acid cycle. Octyl-α-ketoglutarate also prevents succinate or fumarate mediated inhibition of prolyl hydroxylases.
octyl-α-ketoglutarate is a stable, cell-permeable form of α-ketoglutarate, a substrate of prolyl hydroxylases (phd) [1][2].the high turnover of hifα is initiated by prolyl hydroxylases (phd), which hydroxylate proline residues on the oxygen-dependent degradation (odd) domain of hifα, facilitating ubiquitination and degradation. to catalyze proline hydroxylation, phds convert molecular oxygen and α-ketoglutarate to carbon dioxide and succinate [2]. loss of idh1 activity would reduce cellular levels of α-kg [3].octyl-α-ketoglutarate is a cell-permeating α-ketoglutarate derivative, which built up rapidly and preferentially in cells with a dysfunctional tca cycle. octyl-α-ketoglutarate increased intracellular levels of freeα-ketoglutaric acid by approximately fourfold. in hek293-derived cell lines expressing both a gfp-odd fusion protein and ha-tagged pvhl, octyl-α-ketoglutarate reactivated phd activity inhibited by succinate or fumarate. octyl-α-ketoglutarate restored hydroxylation and targeted hif1 for ubiquitylation and proteasomally mediated degradation [2]. octyl-α-ketoglutarate inhibited the hif-1α induction caused by idh1 knockdown in hela cells or overexpression of idh1r132h mutant in u-87mg cells, suggesting a reduction in idh1 activity caused a reduction in α-kg levels that in turn led to stabilization of hif-1α [3].
[1]. gottlieb e, tomlinson ip. mitochondrial tumour suppressors: a genetic and biochemical update. nat rev cancer. 2005 nov;5(11):857-66.
[2]. mackenzie ed, selak ma, tennant da, et al. cell-permeating alpha-ketoglutarate derivatives alleviate pseudohypoxia in succinate dehydrogenase-deficient cells. mol cell biol. 2007 may;27(9):3282-9.
[3]. zhao s, lin y, xu w, et al. glioma-derived mutations in idh1 dominantly inhibit idh1 catalytic activity and induce hif-1alpha. science. 2009 apr 10;324(5924):261-5.
