Renal mtROS, TFAM Turnover, and the Direction of mtDNA Maintenance Failure

**Background:** Renal ischemia-reperfusion and matched oxidative-stress models are often described as a mitochondrial DNA (mtDNA)-reactive oxygen species (ROS) vicious cycle. The unresolved bottleneck is directional: mitochondrial ROS (mtROS) may initiate TFAM-dependent mtDNA-maintenance failure, or primary mtDNA-maintenance defects may initiate ROS as a downstream stress signal. **Objective:** This working paper tests the selected question: In renal ischemia-reperfusion and matched oxidative-stress models, does mitochondrial ROS initiate TFAM-dependent mtDNA-maintenance failure, or do primary mtDNA-maintenance defects initiate ROS as the dominant causal direction? **Methods:** PubMed, PubMed Central, publisher pages, the Mito Map portfolio context and current primary-literature searches were checked on 2026-10-09. Six complete public primary full texts were archived and SHA-256 verified. Endpoint classes were renal same-condition mtROS, TFAM/Lon, mtDNA nucleoid, copy-number, respiration and cytokine endpoints; mtDNA-mutator stem-cell redox; TFAM/Twinkle cardiac copy-number redox; oxidative mtDNA degradation; mitochondrial-catalase skeletal-muscle mtDNA damage; and mitochondrial-superoxide-linked mtDNA adduct measurement. The analysis was a source-coded competing-model evidence synthesis; no pooled effect size, clinical benefit, raw-image reanalysis or universal ROS-first mechanism was inferred. **Results:** The renal anchor supported an mtROS-upstream TFAM mechanism: mtROS suppression restored TFAM and mtDNA copy number in HK-2 oxidative stress, mtROS suppressed TFAM transcription and promoted Lon-mediated TFAM loss, and TFAM knockdown abolished Mito-Tempo rescue of respiration and cytokine outcomes [1]. The same renal source also made bidirectionality unavoidable because TFAM knockdown alone induced mtROS, aberrant nucleoids and respiratory defects [1]. Two competing-direction sources showed that primary mtDNA mutagenesis or TFAM/Twinkle/copy-number manipulation can alter mitochondrial redox outputs in stem-cell and cardiac systems [2,3]. Three measurement-boundary sources showed that oxidative stress can degrade mtDNA without substantial mutagenesis, mitochondrial-catalase expression can protect aging mtDNA-damage endpoints, and mitochondrial superoxide modulation changes a specific mtDNA adduct [4-6]. **Conclusions:** Current public primary evidence supports a directionality rule, not a universal causal slogan. In renal tubular oxidative injury, mtROS can be assigned upstream of TFAM-mediated mtDNA-maintenance failure only when the same condition shows mtROS control restoring TFAM/Lon state, nucleoid organization, mtDNA copy number, respiration and cytokine outcomes, and when TFAM availability is required for that rescue. If TFAM/nucleoid loss precedes mtROS or persists after verified mtROS suppression, the model should be treated as primary mtDNA-maintenance failure, non-mitochondrial ROS injury or parallel injury rather than an mtROS-upstream TFAM mechanism.