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
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
Design
Multi-model interventional study: C. elegans lifespan, unbiased target identification (DARTS-MS), enzyme kinetics, mammalian cell biology, and isolated mitochondrial respiration
Model
C. 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
Sample
Worm lifespan cohorts of 40–121 animals per condition across 2–8 independent experiments; multiple replicates for cell and mitochondrial assays
Intervention
α-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
Duration
Adult worm lifespan (~35 days); acute biochemical assays over minutes to hours
Endpoints
Adult lifespan; ATP content; Oxygen consumption rate; ATP synthase enzyme kinetics; Autophagy (GFP::LGG-1 puncta and LC3 blotting); mTOR pathway phosphorylation (P-S6K T389, P-4E-BP1 S65, P-AKT S473, P-ULK1 S757); Mitochondrial respiratory control ratio · Endogenous α-KG levels in fed vs. starved worms
What the study showed, in plain terms
This landmark 2014 paper — the foundational discovery that placed alpha-ketoglutarate in the longevity supplement conversation — asked whether a common Krebs cycle metabolite could extend lifespan, and if so, how. The UCLA team screened a set of natural metabolites and found that AKG extended the lifespan of adult C. elegans worms by about 50%, with an optimal dose of 8 mM.
Using an unbiased protein target identification technique they developed, called DARTS, the authors discovered that AKG binds directly to ATP synthase — the cellular machine that makes ATP, the universal energy currency. AKG's binding partially inhibits this machine, which lowers ATP levels and mimics a mild form of energy stress. This in turn suppresses the mTOR pathway (a major growth-promoting signal whose inhibition is a well-established longevity mechanism) and activates autophagy (the cellular clean-up process).
Critically, the effects were conserved across species: ATP synthase inhibition and mTOR suppression by AKG were reproduced in human cells and in isolated mouse liver mitochondria. Adding AKG did not further extend the lifespan of worms whose ATP synthase or mTOR was already knocked down, indicating both are essential for the effect. Endogenous AKG levels rose in starved worms, suggesting AKG naturally mediates dietary-restriction-like longevity signalling.
Every subsequent AKG longevity paper — including the mouse healthspan work (Shahmirzadi 2020), the Drosophila mechanism paper (Su 2019), and the human retrospective (Demidenko 2021) — builds directly on this study.
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.
