Hypothesis

Programmed aging is driven by a conserved, gonad‑derived extracellular vesicle (EV) microRNA signal that is released after reproductive maturity and actively suppresses autophagy and lysosomal function in somatic tissues, thereby executing a population‑level senescence program.

Mechanistic Basis

• Reproductive tissues (ovaries/testes) increase secretion of EVs enriched in specific miRNAs (e.g., miR‑34a, miR‑29) once gonadal steroid output peaks, a timing that aligns with species‑specific reproductive schedules [1][2].
• These EVs traverse the circulation and are taken up by liver, muscle, and brain, where the miRNAs directly target key autophagy genes (ATG5, ATG7, LAMP2) and lysosomal acidification components (V‑ATPase subunits).
• Suppression of autophagy leads to accumulation of damaged proteins and organelles, triggering the coordinated epigenomic and transcriptomic remodeling observed across aging tissues [3].
• Because the signal is tied to gonadal activity, its onset is synchronized to the end of the reproductive window, providing a mechanistic basis for the evolutionary advantage of clearing post‑reproductive individuals to reduce kin competition.

Testable Predictions

1. EV miRNA blockade – Inhibiting the release or uptake of gonad‑derived EVs in mid‑aged mice will delay the onset of age‑related autophagy decline and extend healthspan without affecting early‑life fertility.
2. MiRNA specificity – Antisense oligonucleotides against the candidate miRNAs (miR‑34a/miR‑29) administered systemically will recapitulate the lifespan extension seen with EV blockade.
3. Cross‑species conservation – Heterochronic EV plasma transfer from young to old killifish will rescue autophagic flux, whereas old-to-young transfer will accelerate senescence markers in recipients.
4. Falsification – If genetic ablation of EV secretion from gonads does not alter systemic autophagy markers or lifespan, the hypothesis is refuted.

Experimental Approach

• Model: Use inducible Cre‑loxP systems to knock out Rab27a (essential for EV extrusion) specifically in gonads of mice at 6 months (post‑pubertal).
• Readouts: Measure LC3‑II/I ratios, p62 accumulation, and lysosomal cathepsin activity in liver, skeletal muscle, and hippocampus at 3, 6, 12 months; assess frailty index, grip strength, and cognitive performance.
• Lifespan: Track survival cohorts (n ≥ 50 per group) to determine median and maximal lifespan changes.
• Rescue: Gonad‑derived EVs isolated from wild‑type donors will be injected into Rab27a‑KO mice to test whether re‑introduction restores the aging phenotype.
• Omics: Perform small‑RNA sequencing of plasma EVs to confirm miRNA cargo changes; conduct ATAC‑seq and RNA‑seq on target tissues to verify coordinated epigenomic‑transcriptomic shifts.

Implications

If validated, this framework reframes aging as an evolvable signal‑driven program rather than a passive damage accumulation, suggesting that longevity interventions should aim to modulate or evade the gonad‑EV timer instead of overriding downstream damage pathways. It also provides a concrete molecular target (EV miRNA content) for developing therapies that decouple extended somatic maintenance from reproductive fitness, aligning with evolutionary logic while still achieving healthspan gains.