Q-Flux: A method to assess hepatic mitochondrial succinate dehydrogenase, methylmalonyl-CoA mutase, and glutaminase fluxes in vivo

Brandon T. Hubbard, Traci E. LaMoia, Leigh Goedeke, Rafael C. Gaspar, Katrine D. Galsgaard, Mario Kahn, Graeme F. Mason, Gerald I. Shulman

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

The mammalian succinate dehydrogenase (SDH) complex has recently been shown as capable of operating bidirectionally. Here, we develop a method (Q-Flux) capable of measuring absolute rates of both forward (VSDH(F)) and reverse (VSDH(R)) flux through SDH in vivo while also deconvoluting the amount of glucose derived from four discreet carbon sources in the liver. In validation studies, a mitochondrial uncoupler increased net SDH flux by >100% in awake rodents but also increased SDH cycling. During hyperglucagonemia, attenuated pyruvate cycling enhances phosphoenolpyruvate carboxykinase efficiency to drive increased gluconeogenesis, which is complemented by increased glutaminase (GLS) flux, methylmalonyl-CoA mutase (MUT) flux, and glycerol conversion to glucose. During hyperinsulinemic-euglycemic clamp, both pyruvate carboxylase and GLS are suppressed, while VSDH(R) is increased. Unstimulated MUT is a minor anaplerotic reaction but is readily induced by small amounts of propionate, which elicits glucagon-like metabolic rewiring. Taken together, Q-Flux yields a comprehensive picture of hepatic mitochondrial metabolism and should be broadly useful to researchers.

Original languageEnglish
Pages (from-to)212-226.e4
JournalCell Metabolism
Volume35
Issue number1
DOIs
StatePublished - 3 Jan 2023
Externally publishedYes

Keywords

  • anaplerosis
  • glucagon
  • glutaminase
  • insulin
  • mass spectrometry
  • metabolic flux analysis
  • methylmalonyl-CoA mutase
  • mitochondrial metabolism
  • propionate
  • succinate dehydrogenase

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