Tier 3 — preclinical

The metabolite alpha-ketoglutarate extends lifespan by inhibiting the ATP synthase and TOR

Chin RM, Fu X, Pai MY, Vergnes L, Hwang H, Deng G, Diep S, Lomenick B, Meli VS, Monsalve GC, Hu E, Whelan SA, Wang JX, Jung G, Solis GM, Fazlollahi F, Kaweeteerawat C, Quach A, Nili M, Krall AS, Godwin HA, Chang HR, Faull KF, Guo F, Jiang M, Trauger SA, Saghatelian A, Braas D, Christofk HR, Clarke CF, Teitell MA, Petrascheck M, Reue K, Jung ME, Frand AR, Huang J
Nature 2014 Volume 510, issue 7505, pages 397–401

Bibliography

PubMed
PMID 24828042
PubMed Central
PMC4263271
DOI
10.1038/nature13264
Funding
The U.S. National Institutes of Health for traineeship support of R.M.C. (T32 GM007104), M.Y.P. (T32 GM007185), B.L. (T32 GM008496), and M.N. (T32 CA009120). X.F. is a recipient of the China Scholarship Council Scholarship. G.C.M. was supported by Ford Foundation and National Science Foundation Graduate Research Fellowships.
Competing interests
The authors declare no competing financial interests.

Study snapshot

DesignMulti-model interventional study: C. elegans lifespan, unbiased target identification (DARTS-MS), enzyme kinetics, mammalian cell biology, and isolated mitochondrial respiration
ModelC. elegans (Bristol N2 wild-type plus mutants: eat-2, daf-2, daf-16, aak-2, pha-4, hif-1, egl-9, vhl-1); human cell lines (Jurkat, HeLa, HEK-293, WI-38, U87); MEFs; isolated mouse liver mitochondria
SampleWorm lifespan cohorts of 40–121 animals per condition across 2–8 independent experiments; multiple replicates for cell and mitochondrial assays
Interventionα-KG supplementation to NGM agar (0.5–20 mM; 8 mM optimal) from young adulthood in worms; membrane-permeable octyl α-KG (100–800 μM) in cells and mitochondria; oligomycin used as ATP synthase inhibitor comparator
DurationAdult worm lifespan (~35 days); acute biochemical assays over minutes to hours
EndpointsC. elegans lifespan; ATP synthase target engagement/activity; Cellular ATP levels; TOR/mTOR signaling; Autophagy-related signaling; Mitochondrial respiratory control ratio; Endogenous α-KG levels in fed vs. starved worms

What the study showed, in plain terms

This 2014 study asked whether alpha-ketoglutarate (AKG), a normal tricarboxylic-acid-cycle metabolite, could affect lifespan in the nematode C. elegans. In the reported experiments, 8 mM AKG extended adult worm lifespan by roughly 50%.

Mechanistic work linked AKG with inhibition of ATP synthase, lower cellular ATP, reduced TOR/mTOR-related signaling and increased autophagy-related activity. Genetic interaction experiments in C. elegans supported substantial pathway overlap: AKG did not add further lifespan extension when ATP synthase or TOR-pathway components were already reduced.

Mechanistic effects were also tested outside the worm lifespan experiment: AKG inhibited ATP synthase in biochemical assays, altered ATP/mTOR-related signaling in cultured mammalian cells, and affected respiration in isolated mouse liver mitochondria. Those experiments support biological plausibility but do not demonstrate mammalian lifespan extension.

The paper established an influential experimental link among AKG, ATP synthase, TOR signaling and lifespan regulation in C. elegans. It does not provide human longevity evidence.

Key findings

  • α-KG at 8 mM extended adult C. elegans lifespan by an average of 47.3% across three independent experiments (all p < 0.0001), with maximum effect around 50%; supplementation beginning at the adult stage was sufficient.
  • The DARTS-MS unbiased target identification method identified ATP synthase subunit β (ATP5B) as the most enriched α-KG-binding protein in human Jurkat cells; the interaction was confirmed for C. elegans ATP-2 homolog.
  • α-KG inhibits ATP synthase (Complex V) enzyme activity as an uncompetitive inhibitor, decreasing apparent Vmax from 53.9 to 26.7 and Km from 25.9 to 15.4 in isolated mouse liver mitochondria.
  • Cellular ATP levels dropped significantly in octyl α-KG-treated human fibroblasts (p = 0.0016) and in α-KG-treated worms at day 8 of adulthood (p = 0.012); oxygen consumption fell in both systems (p < 0.0001).
  • α-KG did not further extend the lifespan of atp-2(RNAi) or CeTOR(RNAi) worms, indicating both ATP synthase and TOR are required for the longevity effect. It did further extend daf-2 mutants (p < 0.0001).
  • Phosphorylation of mTOR substrates S6K (T389), 4E-BP1 (S65), AKT (S473), and ULK1 (S757) decreased in mammalian cells treated with octyl α-KG or oligomycin, confirming TOR pathway inhibition downstream of ATP synthase.
  • Autophagy (GFP::LGG-1 puncta in worms; LC3-II conversion in mammalian cells) increased with α-KG treatment; no further increase in atp-2(RNAi) or CeTOR(RNAi) worms.
  • Endogenous α-KG levels rose ~2-fold in starved worms compared to fed controls (p < 0.01), supporting a model where α-KG mediates dietary-restriction-like longevity signalling.
  • Oligomycin (a direct ATP synthase inhibitor) also extended worm lifespan (32.3% at 40 μM), reinforcing that ATP synthase inhibition is a valid longevity intervention.

What this study can and cannot tell us

Lifespan data are from C. elegans, an invertebrate with substantial biology in common with humans but with a lifespan measured in weeks and metabolism that differs in important ways. The 8 mM optimal external concentration on agar plates corresponds to a ~50% increase in intracellular α-KG (from ~110 to ~160 μM assuming homogeneous distribution) — this internal delta cannot be assumed to translate directly to any human dosing regimen.

Mammalian data are from cell lines and isolated mouse mitochondria, not from intact animals. The subsequent Shahmirzadi 2020 mouse study addressed the in vivo mammalian question, but that paper was published six years later; at the time of Chin 2014, the mouse lifespan question was open.

The DARTS method identifies binding partners but does not rank binding affinities in absolute terms; the α-KG–ATP5B interaction is well-supported but the interaction with the α subunit (ATP5A) was also enriched, and other undiscovered targets cannot be excluded.

No human data. The paper does not test AKG in any human, cell-line or otherwise, at the organism level.

The lifespan extension effect at 8 mM in worms partially depends on AMPK and FoxO (aak-2 and daf-16 mutants show reduced but not abolished effect), suggesting the pathway wiring may be more complex than the ATP synthase → TOR axis alone.

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Dr. Khaled Mahmoud, MBBChCritical Care Medicine, Longevity Science & Editorial Direction Dr. Amr Yasser, PhDCardiometabolic, Musculoskeletal, Gut & Bioavailability Dr. Abdulla Mostafa, PhDCellular Senescence, Neurological, Mitochondrial & Brain-Ageing Biology