Hypothesis

Age‑associated decline of TET enzyme activity reduces 5hmC at promoters of proteostasis genes, triggering a shift from soluble chaperone‑mediated refolding to the formation of structured, amyloid‑like aggregates that sequester misfolded proteins and limit proteotoxic stress.

Mechanistic Rationale

TET‑mediated hydroxymethylation maintains an open chromatin state at loci encoding HSP70, HSP90 and components of the ubiquitin‑proteasome system [1]. In aging T‑cells, global 5hmC erosion diminishes transcription of these genes, weakening dynamic protein quality control. When refolding capacity falls below a threshold, the cell redirects excess misfolded proteins into ordered, β‑sheet‑rich deposits. These aggregates are not random garbage; they arise because the remaining proteostasis network favors thermodynamic minimization via amyloid formation, converting toxic oligomers into inert, sequestered matrices. Restoring 5hmC (e.g., via TET overexpression or Vitamin C) should re‑activate chaperone expression, dissolve the aggregates, and restore proteasome flux.

Testable Predictions

1. Aged human CD4+ T‑cells will show a significant inverse correlation between 5hmC levels at HSP70/HSP90 promoters and the abundance of Thioflavin‑T‑positive aggregates.
2. Pharmacological inhibition of TET activity in young T‑cells will recapitulate the aged epigenetic profile and increase ordered aggregate formation without raising total ubiquitinated protein load.
3. Genetic rescue of TET2 or treatment with a 5hmC‑enhancing agent will reduce aggregate burden, increase soluble HSP70 levels, and improve cytokine production upon stimulation.
4. Isolated aggregates from aged T‑cells will exhibit protease resistance, amyloid‑like fibril morphology under electron microscopy, and the ability to sequester model misfolded substrates in vitro.

Experimental Approach

• Isolate naïve and memory CD4+ T‑cells from young (20‑30 yr) and elderly (65‑75 yr) donors.
• Measure locus‑specific 5hmC using hMeDIP‑qPCR at HSPA1A (HSP70) and HSP90AA1 promoters; correlate with global 5hmC loss [3].
• Quantify aggregates via filter‑trap assay and Thioflavin‑T fluorescence; confirm morphology by TEM.
• Modulate TET activity: (a) CRISPR‑Cas9 knockout of TET2 in young cells, (b) lentiviral TET2 overexpression in old cells, (c) 50 µM Vitamin C treatment.
• Assess chaperone mRNA/protein levels (RT‑qPCR, Western blot), proteasome activity (LLVY‑AMC assay), and functional readouts (IL‑2 secretion, proliferation).
• Perform in‑vitro seeding assays: incubate purified aggregates with recombinant luciferase to test sequestration capacity.

If TET loss drives ordered aggregate formation as a adaptive response, restoring 5hmC should dissolve these structures and rescue proteostasis. Failure to observe these relationships would falsify the hypothesis, indicating that aggregates in aging T‑cells are purely pathological byproducts.