Presence of telomeric G-strand tails in the telomerase catalytic subunit TERT knockout mice

Genes Cells. 1999 Oct;4(10):563-72. doi: 10.1046/j.1365-2443.1999.00284.x.


Background: Telomerase consists of two essential subunits, the template RNA (TR; telomerase RNA) and the catalytic subunit TERT (telomerase reverse transcriptase). Knockout mice with a mTR (mouse TR) deletion have been described and well characterized. However, mice with a mTERT (mouse TERT) deletion have not been reported.

Results: mTERT-knockout mice have been constructed. The first generation mTERT -/- mice were fertile, and did not show any noticeable macroscopic or microscopic phenotypic change. All tissue cells derived from mTERT -/- mice that were examined lacked telomerase activity, indicating that mTERT is the only gene encoding the telomerase catalytic subunit. Pulse field gel electrophoresis (PFGE) and nondenaturing in-gel hybridization analyses showed that mouse telomeric DNA has G-strand 5'-overhangs, as demonstrated for human and yeast cells. This telomeric single-stranded G-tail was also observed in MEF (mouse embryonic fibroblast) and liver cells derived from mTERT -/- mice.

Conclusions: mTERT-knockout mice show phenotypes that are apparently normal at least during the early generations. This observation is similar to that obtained with the mTR-knockout mice. The presence of the telomeric G-strand tails in mTERT -/- mice suggests that these telomeric 5'-overhangs are produced by telomerase-independent mechanisms, as has been proposed for yeast and human.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Catalytic Domain / genetics*
  • Cell Extracts
  • DNA / analysis
  • DNA-Binding Proteins
  • Electrophoresis, Gel, Pulsed-Field
  • HeLa Cells
  • Humans
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Molecular Sequence Data
  • RNA*
  • Telomerase / genetics*
  • Telomerase / metabolism
  • Testis / anatomy & histology


  • Cell Extracts
  • DNA-Binding Proteins
  • telomerase RNA
  • RNA
  • DNA
  • TERT protein, human
  • Telomerase
  • Tert protein, mouse