Sequential D+Q senolytic priming followed by mifepristone-mediated GR antagonism repairs post-senolytic mitochondrial...

IF a sequential two-phase intervention — oral gavage of dasatinib (5 mg/kg) + quercetin (50 mg/kg) for 3 consecutive days followed 7 days later by mifepristone (10 mg/kg IP, 3×/week, 8 weeks) — is administered to 18-month-old male and female C57BL/6J mice (and age-matched PINK1-knockout controls),

THEN compared with D+Q-only controls, mifepristone-treated wildtype mice will show ≥40% reduction in p16INK4a+ cell frequency and SA-β-gal activity in liver, kidney, and gastrocnemius muscle, a ≥1.5-fold increase in mt-Keima acid:neutral ratio in freshly isolated hepatocytes and muscle fibers, and ≥30% reduction in plasma IL-6 and MCP-1 — with complete or near-complete abolition of all three effects in PINK1-KO cohorts —

BECAUSE the following causal chain, grounded in the Evidence Set, is operative:

1. Senescent hepatocytes and myocytes harbor structurally dysfunctional mitochondria with reduced fatty acid oxidation capacity and compromised membrane potential, constituting the accumulated mitochondrial damage that drives the senescent phenotype in aged tissue rather than merely correlating with it. (Senescent hepatocytes display mitochondrial dysfunction)[https://doi.org/10.1038/ncomms15691]

2. Damaged mitochondria in senescent and paracrine-stressed bystander cells generate cytosolic mtDNA and reactive oxygen species that fuel retrograde mitochondria-to-nucleus signaling; targeted depletion of mitochondria in senescent cells suppresses a 31-gene SASP mRNA panel and reduces IL-8 protein, demonstrating that mitochondrial status is a mechanistic upstream driver of the SASP, not a downstream consequence. (Mitochondrial depletion downregulates SASP)[https://doi.org/10.1101/gad.331272.119]

3. D+Q senolytic clearance removes the dominant burden of p16INK4a+ cells but leaves behind a post-senolytic microenvironment in which surviving parenchymal cells retain damaged, autophagy-refractory mitochondria. These residual organelles sustain low-grade mtDNA leakage and non-mitochondrial ROS production sufficient to drive senescence reaccumulation within 4–8 weeks — a window confirmed by senostatic studies demonstrating that SASP-associated extracellular hydrogen peroxide rebounds rapidly when mitochondrial quality control is not restored. (Senescence-associated H2O2 rebounds with incomplete mitochondrial control)[https://doi.org/10.7554/elife.75492]

4. Chronic glucocorticoid receptor (GR) activation in aged tissues suppresses AMPK/ULK1-dependent autophagic initiation and transcriptionally represses autophagy-related genes (Map1lc3b, Becn1), creating a permissive state for damaged mitochondrial accumulation. Mifepristone's high-affinity GR antagonism [SPECULATIVE link to direct PINK1/Parkin activation — no published direct mechanistic evidence exists] disinhibits the AMPK→ULK1→FIP200 axis in hepatocytes and myocytes, permitting re-engagement of mitophagy initiation machinery.

5. Re-engagement of autophagic initiation in a PINK1-competent cellular context pe...

SENS category: LysoSENS

Key references: • doi.org/10.1038/ncomms15691] • doi.org/10.1101/gad.331272.119] • doi.org/10.7554/elife.75492] • doi.org/10.1155/2020/4939310] • doi.org/10.1016/j.ebiom.2017.04.013]