Hypothesis: Synchronizing Senolytic Clearance with Circadian Proteasome Peaks Enables Safe Conversion of Protective Aggregates into Degradable Substrates

Core Idea

We propose that the therapeutic window for senolytic drugs should be tightly coupled to the refeeding phase of time‑restricted eating, when fasting‑induced transcriptional programs boost proteasome capacity. In this window, senolytic‑mediated removal of senescent cells reduces the influx of new misfolded proteins, while the heightened proteasome activity can safely solubilize pre‑existing chaperone‑rich aggregates without generating toxic oligomers.

Mechanistic Reasoning

• Aggregate sequestration as a last‑resort order: In aged cells, persistent proteostasis stress drives the formation of amyloid‑like deposits that are enriched for HSP70/HSP90 chaperones, effectively locking away dangerous conformers (Protein aggregation as a protective mechanism).
• Risk of premature dissolution: Artificial disruption of these deposits before clearance systems are restored exposes hydrophobic patches that can sequester functional proteins, increasing proteotoxicity (PLOS Biology article).
• Senolytic‑driven autophagy boost: Senolytics activate AMPK/SIRT1 pathways, enhancing autophagic flux and reducing the burden of misfolded proteins that feed aggregate formation (PMC12681496).
• Fasting‑triggered proteasome switch: A 16‑hour fast induces a circadian transcriptional program that up‑regulates 43 proteasome subunits, peaking during the subsequent refeeding window (PMC9671760).
• Combined effect: By administering senolytics at the onset of refeeding, we simultaneously lower the supply of new damaged proteins (via senescent‑cell clearance) and maximize the cell’s capacity to process released aggregates, shifting the equilibrium from inert sequestration to productive degradation.

Testable Predictions

1. In vivo: In aged mice undergoing 16‑hour time‑restricted feeding, senolytic (e.g., dasatinib + quercetin) given at the start of the refeeding period will reduce insoluble HSP70‑positive aggregates in brain and liver more than the same senolytic given during the fasting window, without increasing soluble oligomeric species.
2. In vitro: Primary fibroblasts from old donors treated with a senolytic will show decreased aggregate solubility only when co‑treated with a proteasome activator (e.g., IU1) that mimics the fasting‑induced transcriptional state; proteasome inhibition will abolish the benefit and increase cytotoxicity.
3. Biomarker: Circulating levels of HSP70‑containing extracellular vesicles will drop specifically when senolytics are timed to refeeding, indicating safe aggregate clearance rather than pathological release.

Falsification

If senolytic administration during refeeding fails to lower aggregate burden or leads to a rise in soluble toxic oligomers compared with fasting‑timed dosing, the hypothesis would be refuted, indicating that aggregate dissolution requires additional or different clearance enhancements.