Core Literature Evidence Chain Supporting the "Metabolic   Pathological Lock-Chain" Hypothesis

The following literature collectively forms the core evidence chain for   the complete hypothesis: High-calorie diet → Reductive stress → ROS burst   → Primary inactivation of aconitase → Citrate accumulation → SLC25A1 efflux →   Acetyl-CoA shunting (DAG → Insulin resistance + Histone acetylation → SASP).

I. Aconitase: The "Primary Target" of ROS Attacks

1. Core Mechanism Review (2019, Accounts of Chemical Research)

Castro L, Tórtora V, Mansilla S, Radi R. Aconitases: Non-redox   Iron-Sulfur Proteins Sensitive to Reactive Species. Accounts of Chemical   Research. 2019;52(9):2609-2619.

• Core        Contribution: This        review systematically elucidates the molecular basis of aconitase as a        "primary target" for ROS and RNS. The article points out that        only three iron ions in the aconitase [4Fe-4S] cluster bind to cysteine        thiol ligands, while the fourth iron ion (Feα) is directly exposed to        the solvent and binds to the substrate. This unique structure makes it        the preferred target for ROS attacks. The reaction rate between        superoxide anions (O₂•⁻) and the        Fe-S cluster is as high as ~10⁷ M⁻¹s⁻¹, which is highly specific and        reversible. Consequently, the quantification of active aconitase has        been used as an indicator for assessing intracellular O₂•⁻        generation.

2. Quantitative Study on Reaction Rate Constants (2023, Free Radical   Biology and Medicine)

Mansilla S, et al. Redox sensitive human mitochondrial aconitase and its   interaction with frataxin: In vitro and in silico studies confirm that it   takes two to tango. Free Radical Biology and Medicine.   2023;198:107-120.

• Core        Contribution: This study        directly measured the reaction rate constants of human mitochondrial        aconitase (ACO2) with various ROS:

• The study        also found that the thermal stability of the oxidized [3Fe-4S]⁺ state        significantly decreased, with the melting temperature dropping from 51.1°C to 43.6°C. Furthermore, it confirmed that mitochondrial aconitase        (ACO2) is a major target of oxidative damage in aging and mitochondrial        dysfunction-related diseases.

3. Quantitative Analysis of Aconitase as a Metabolic Control Node (2014,   Free Radical Research)

Scandroglio F, Tórtora V, Radi R, Castro L. Metabolic control analysis   of mitochondrial aconitase: influence over respiration and mitochondrial   superoxide and hydrogen peroxide production. Free Radical Research.   2014;48(6):684-693.

• Core        Contribution: Metabolic        control analysis revealed that the flux control coefficient of aconitase        over respiration exceeds 0.95 in the brain and heart. This means that in        these high-energy-demand tissues, even a minor decrease in aconitase        activity can significantly impact mitochondrial respiration and ROS        production. This finding upgrades aconitase from a "damaged        enzyme" to an "amplifier of metabolic collapse."

4. Supporting Literature: Discussions on Fe-S Cluster Oxidative Damage   in Nature

• Nature (2021): Sulfur sequestration promotes multicellularity        during nutrient limitation. The text explicitly states:        "Aconitase requires its FeS cluster to metabolize citrate in the        TCA cycle... Mitochondrial superoxide can degrade the FeS cluster of        mitochondrial aconitase." This cross-disciplinary study        corroborates the ROS sensitivity of aconitase.

• Nature        Communications (2025): Critical role of mitochondrial aconitase in        skeletal muscle maturation. This study describes ACO2 as an        "iron-sulfur protein containing a [4Fe-4S] cluster... whose        iron-sulfur cluster is fragile and can be disrupted by oxidative stress        or hypoxia, leading to iron release and enzyme functional        inactivation."

II. July 29, 2026 Nature Study: The SLC25A1-SASP Pathway

Martini H, Birch J, Marques FDM, et al. Mitochondrial metabolism and   epigenetic crosstalk drive SASP. Nature. 2026;656:980-992.

• Core        Contributions:

• Pathway         Discovery: In         senescent cells, the mitochondrial pyruvate-citrate-acetyl-CoA axis is         upregulated, increasing acetyl-CoA availability to support histone         acetylation at SASP genes.

• Key         Transporter: SLC25A1         (mitochondrial citrate export protein) is the crucial molecule         transporting mitochondrial citrate into the cytosol. Inhibiting SLC25A1         reduces histone acetylation at SASP loci and limits the activity of         inflammatory programs.

• In Vivo         Validation: In aged         mice, inhibiting SLC25A1 reduces chromatin accessibility at SASP loci,         suppresses inflammation, and improves healthspan.

• Core         Mechanism Positioning:         This study reveals that "mitochondrial metabolism provides a         second layer of control that enables the execution of inflammatory         programs." In other words, beyond the activation of transcription         factors via the classical cGAS-STING pathway, the availability of         acetyl-CoA is essential for the robust transcription of SASP genes.

• Selective         Intervention: Targeting         SLC25A1 can selectively inhibit the inflammatory output of senescent         cells without reversing cellular senescing itself—achieving a precise         anti-inflammatory effect of "putting out the fire without         dismantling the house."

III. Mechanism of Acetyl-CoA → DAG → Insulin Resistance Formation

1. Classic Review on the DAG-PKCθ Axis (Cell, 2012)

Samuel VT, Shulman GI. Mechanisms for insulin resistance: common threads   and missing links. Cell. 2012;148(5):852-871.

• Core        Contribution: This        review (and its derivative diagrams) systematically elucidates the core        mechanisms of lipid-induced insulin resistance:

• Skeletal         Muscle Insulin Resistance:         Increased ectopic lipids in muscle cells → Accumulation of         diacylglycerol (DAG) → Activation of PKCθ → Inhibition of the PI3K         pathway via inhibitory phosphorylation of IRS1 → Impairment of         insulin-stimulated glucose transport and glycogen synthesis.

• Hepatic         Insulin Resistance: Lipid         accumulation in the liver → Activation of the DAG-PKCε axis →         Inhibitory phosphorylation of the insulin receptor (Thr1160) →         Impairment of hepatic glycogen synthesis and transcriptional regulation         of gluconeogenesis.

2. Human Lipidomics Evidence (Scientific Reports, 2025)

Skeletal muscle insulin resistance in prediabetes: a lipidomic   perspective on diacylglycerols, ceramides, and phospholipids. Scientific   Reports. 2025.

• Core        Contribution: In        prediabetic patients, impaired skeletal muscle insulin sensitivity is        associated with the accumulation of triglycerides and        1,3-diacylglycerols, driven by the buildup of lipotoxic metabolites.        This study extends the DAG-insulin resistance mechanism from animal        models to human clinical samples.

3. Tissue Specificity of DAG-PKC (Diabetologia, 2001)

Protein kinase C activation: isozyme-specific effects on metabolism and   cardiovascular complications in diabetes. Diabetologia. 2001.

• Core        Contribution: This        foundational early study pointed out that the activation of        DAG-sensitive PKC isoforms (PKCθ and PKCε) downregulates insulin        receptor signaling, serving as a crucial biochemical mechanism linking        lipid metabolism disorders to muscle insulin resistance.

4. High-Fat Diet Animal Models (Scientific Reports, 2021)

Distinct mechanisms involving diacylglycerol, ceramides, and   inflammation underlie insulin resistance in oxidative and glycolytic muscles   from high fat-fed rats. Scientific Reports. 2021.

• Core        Contribution: A high-fat        diet leads to the accumulation of DAG and ceramides, PKC activation, and        the induction of inflammatory pathways, confirming the causal role of        the DAG-PKC axis in diet-induced insulin resistance.

IV. Integrated Relationships Among the Three Literature Chains

V. Supplementary Recommended Authoritative Reviews

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