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Mechanism

Telomerase (TERT / TERC)

Reference definition for a telomere-biology node.

Enzyme / core function
Two caveats govern every page on this site. (1) Telomere length is a contested aging biomarker — it is measured differently by different methods, varies between tissues, and "longer" is not straightforwardly "healthier"; changing a telomere-length or telomerase-activity number in a trial is not the same as slowing human aging. (2) Activating telomerase is not risk-free — telomerase is silenced in most somatic cells and reactivated in most cancers, so its activation raises an unresolved cancer-risk question. Tellingly, the only FDA-approved telomerase drug — imetelstat (RYTELO, 2024) — inhibits telomerase to treat cancer (lower-risk MDS), the opposite direction from the anti-aging "activation" narrative.

Definition

Category: Enzyme / core function

Also known as: telomerase reverse transcriptase, TERT, TERC, hTERT

Telomerase is the ribonucleoprotein reverse transcriptase that extends telomeres, built around the catalytic protein subunit TERT and the RNA template TERC. It is active in germline, stem, and most cancer cells but is largely silenced in normal somatic cells, which is why those cells shorten their telomeres with division. Telomerase is the direct target of the 'activation' narrative — and of the opposite-direction inhibitor imetelstat.

Key points

  • TERT (the protein) plus TERC (the RNA template) form the core enzyme; loss-of-function mutations cause telomere-biology disorders (telomeropathies) such as dyskeratosis congenita and some idiopathic pulmonary fibrosis.
  • Somatic silencing of telomerase is thought to be tumour-suppressive: it limits how many times a damaged cell can divide.
  • Because telomerase is reactivated in the large majority of cancers, activating it pharmacologically raises an unresolved cancer-risk question (see the telomerase–cancer paradox page).

Related interventions

Sourcing

Standard telomerase enzymology reviews (Greider & Blackburn; Shay & Wright). Review-level description.

Reference synthesis (tier 4); verification: review_level_2026-07-12.