Intermittent Cold Exposure Lowers Telomeric Entropy via Shelterin‑TERRA Phase Separation to Delay Senescence

Hypothesis

Intermittent cold exposure reduces telomeric informational entropy by promoting ordered shelterin‑TERRA phase separation, thereby attenuating replicative senescence.

Mechanistic Rationale

Telomeres behave as biophysical condensates where telomeric repeat‑containing RNA (TERRA) and shelterin proteins form liquid‑like droplets whose internal disorder reflects informational entropy. It's known that chronic oxidative stress increases TERRA phosphorylation, raising droplet entropy and accelerating telomere attrition via impaired t‑loop formation. In contrast, brief cold spikes activate the heat‑shock factor HSF1 and downstream HSP90, which dephosphorylate TERRA and stabilize shelterin interactions, lowering droplet entropy and preserving telomere length. This mechanism links hormetic temperature cycles to a quantum‑like information metric without invoking unexplained physics.

Testable Predictions

1. Single‑molecule FRET entropy measurements will show lower entropy values in telomeres from cells subjected to intermittent cold (e.g., 4 °C 2 min × 4 cycles with 10 min recovery) compared to cells exposed to continuous cold or normothermia.
2. Telomerase activity (TRAP assay) will be significantly higher after intermittent cold regimens, correlating with reduced TERRA phosphorylation (Western blot with phospho‑specific antibody).
3. The shortest telomere length per cell, measured by STELA, will be preserved after intermittent cold but shortened after chronic cold exposure.
4. Inhibiting HSP90 with geldanamycin will abolish the protective effect of intermittent cold on telomere entropy and length.

Experimental Design

• Culture human fibroblasts (IMR‑90) under three conditions: (a) intermittent cold (4 °C 2 min pulses, 4×/day, 10 min recovery at 37 °C), (b) chronic cold (continuous 4 °C), (c) control (37 °C).
• After 14 days, isolate nuclei and perform:
  • smFRET on telomeric repeats to compute Shannon entropy of distance distributions.
  • Immunofluorescence for TERRA and shelterin (TRF2) co‑localization, quantified via Pearson’s coefficient.
  • TRAP assay for telomerase activity.
  • STELA for shortest telomere length.
• Repeat with HSP90 inhibitor added to intermittent cold group. Statistical analysis: ANOVA with Tukey post‑hoc; significance set at p<0.05.