Telomerelength modulates m6A-dependent proteostasis via a nuclear-retrograde signaling pathway

Core Hypothesis

Telomere length directly influences the deposition of N6-methyladenosine (m6A) on transcripts that encode proteostasis regulators, such that shortened telomeres reduce m6A deposition and compromise protein-quality control, independent of cell-division count.

Mechanistic Rationale

• Telomeres shelter chromosome ends and recruit a network of DNA-damage-response proteins that can alter chromatin states at subtelomeric regions.
• Shortened telomeres increase the abundance of telomeric repeat-containing RNA (TERRA), which can bind to and sequester the m6A writer complex METTL3/METTL14 in the nucleus.
• Reduced nuclear METTL3/14 activity lowers m6A installation on 3'UTRs of synaptic and autophagy-related mRNAs, decreasing their stability and translation.
• Consequently, proteostasis capacity declines, leading to accumulation of misfolded proteins—a hallmark of aging and neurodegeneration.
• This model frames telomere shortening as a sensor of nuclear-retrograde stress that couples chromosomal integrity to epitranscriptomic regulation, offering a mechanistic bridge between the 'quantum-clock' idea and established m6A-aging data.

Testable Predictions

1. In human induced pluripotent stem cell-derived neurons, acute telomere shortening (via CRISPR-mediated TRF2 knockout) will decrease METTL3 chromatin occupancy and global m6A levels on 3'UTRs of proteostasis genes without altering proliferation rate.
2. Restoring telomere length with telomerase (TERT overexpression) will rescue METTL3 binding, increase m6A on targets such as USP14 and BECN1, and reduce poly-ubiquitin-positive aggregates.
3. Artificial increase of TERRA levels in telomere-intact neurons will phenocopy the m6A loss and proteostatic decline seen with telomere shortening.
4. Conversely, inhibiting TERRA transcription with antisense oligonucleotides will preserve m6A deposition and proteostasis despite critically short telomeres.

Experimental Approach

• Generate isogenic neuronal lines with inducible TRF2-FKBP degron for rapid telomere-uncapping.
• Measure TERRA RNA by RT-qPCR, METTL3 ChIP-seq, and m6A-seq (MeRIP-seq) at 0, 24, 48 h post-induction.
• Quantify m6A-modified transcripts encoding proteostasis factors (e.g., USP14, p62, LAMP1) and assess their half-life via transcriptional shut-off assays.
• Monitor protein aggregation using filter-trap assay and fluorescent reporters for poly-Q or α-synuclein.
• Rescue experiments: co-express TERT or deliver METTL3-mRNA; assess whether m6A and proteostasis metrics normalize.
• Controls: non-targeting gRNA, senescence-associated β-galactosidase staining to confirm that observed effects are not secondary to proliferation arrest.

If predictions hold, telomere length would act as a regulator of epitranscriptomic balance, linking chromosomal aging to translational control of proteostasis. Failure of this axis would provide a testable, mechanistic explanation for why telomere attrition correlates with neurodegeneration, reframing the 'quantum clock' notion as a concrete signal-transduction pathway rather than a metaphorical entropy meter.