Metabolic fingerprinting reveals extensive consequences of GLS [glutaminase] hyperactivity, 2019, Rumping et al

Andy · Nov 18, 2019

Highlights

• Expression of a hypermorphic GLS variant in combination with incremental GLS inhibition results in different glutamine/glutamate ratios.
• DI-HRMS in cultured cells provides an in-depth metabolic fingerprint recapitulating part of the metabolic consequences of in vivo enhanced GLS activity.
• High GLS activity solely is sufficient to cause a truncated TCA cycle.
• High GLS activity may negatively impact pyrimidine metabolism.

Abstract
Background
High glutaminase (GLS;EC3.5.1.2) activity is an important pathophysiological phenomenon in tumorigenesis and metabolic disease. Insight into the metabolic consequences of high GLS activity contributes to the understanding of the pathophysiology of both oncogenic pathways and inborn errors of glutamate metabolism. Glutaminase catalyzes the conversion of glutamine into glutamate, thereby interconnecting many metabolic pathways.

Methods
We developed a HEK293-based cell-model that enables tuning of GLS activity by combining the expression of a hypermorphic GLS variant with incremental GLS inhibition. The metabolic consequences of increasing GLS activity were studied by metabolic profiling using Direct-Infusion High-Resolution Mass-Spectrometry (DI-HRMS).

Results and conclusions
Of 12,437 detected features [m/z], 109 features corresponding to endogenously relevant metabolites were significantly affected by high GLS activity. As expected, these included strongly decreased glutamine and increased glutamate levels. Additionally, increased levels of tricarboxylic acid (TCA) intermediates with a truncation of the TCA cycle at the level of citrate were detected as well as increased metabolites of transamination reactions, proline and ornithine synthesis and GABA metabolism. Levels of asparagine and nucleotide metabolites showed the same dependence on GLS activity as glutamine. Of the nucleotides, especially metabolites of the pyrimidine thymine metabolism were negatively impacted by high GLS activity, which is remarkable since their synthesis depend both on aspartate (product of glutamate) and glutamine levels. Metabolites of the glutathione synthesizing γ-glutamyl-cycle were either decreased or unaffected.

General significance
By providing a metabolic fingerprint of increasing GLS activity, this study shows the large impact of high glutaminase activity on the cellular metabolome.
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Open access, https://www.sciencedirect.com/science/article/pii/S0304416519302739

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Metabolic fingerprinting reveals extensive consequences of GLS [glutaminase] hyperactivity, 2019, Rumping et al

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Metabolic fingerprinting reveals extensive consequences of GLS [glutaminase] hyperactivity, 2019, Rumping et al

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