Parker Seth J, Encarnación-Rosado Joel, Hollinshead Kate E R, Hollinshead David M, Ash Leonard J, Rossi Juan A K, Lin Elaine Y, Sohn Albert S W, Philips Mark R, Jones Drew R, Kimmelman Alec C
Department of Radiation Oncology, New York University School of Medicine, New York, NY, USA.
Perlmutter Cancer Center, New York University School of Medicine, New York, NY, USA.
Nat Commun. 2021 Aug 12;12(1):4905. doi: 10.1038/s41467-021-25228-9.
α-ketoglutarate (KG), also referred to as 2-oxoglutarate, is a key intermediate of cellular metabolism with pleiotropic functions. Cell-permeable esterified analogs are widely used to study how KG fuels bioenergetic and amino acid metabolism and DNA, RNA, and protein hydroxylation reactions, as cellular membranes are thought to be impermeable to KG. Here we show that esterified KG analogs rapidly hydrolyze in aqueous media, yielding KG that, in contrast to prevailing assumptions, imports into many cell lines. Esterified KG analogs exhibit spurious KG-independent effects on cellular metabolism, including extracellular acidification, arising from rapid hydrolysis and de-protonation of α-ketoesters, and significant analog-specific inhibitory effects on glycolysis or mitochondrial respiration. We observe that imported KG decarboxylates to succinate in the cytosol and contributes minimally to mitochondrial metabolism in many cell lines cultured in normal conditions. These findings demonstrate that nuclear and cytosolic KG-dependent reactions may derive KG from functionally distinct subcellular pools and sources.
α-酮戊二酸（KG），也被称为2-氧代戊二酸，是细胞代谢的关键中间体，具有多种功能。由于细胞膜被认为对KG不可渗透，因此细胞可渗透的酯化类似物被广泛用于研究KG如何为生物能量和氨基酸代谢以及DNA、RNA和蛋白质羟基化反应提供能量。在这里，我们表明酯化的KG类似物在水性介质中迅速水解，产生的KG与普遍的假设相反，能够进入许多细胞系。酯化的KG类似物对细胞代谢表现出与KG无关的虚假效应，包括细胞外酸化，这是由α-酮酯的快速水解和去质子化引起的，并且对糖酵解或线粒体呼吸有显著的类似物特异性抑制作用。我们观察到，导入的KG在细胞质中脱羧生成琥珀酸，在正常条件下培养的许多细胞系中，对线粒体代谢的贡献最小。这些发现表明，细胞核和细胞质中依赖KG的反应可能从功能不同的亚细胞池和来源获得KG。
