title: Presence of telomeric G-strand tails in the telomerase catalytic subunit TERT knockout mice.
abstract: 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.
authors.affiliation: Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama, 226-8501, Japan.
authors.forename: X
authors.initials: X
authors.lastname: Yuan
authors.forename: S
authors.initials: S
authors.lastname: Ishibashi
authors.forename: S
authors.initials: S
authors.lastname: Hatakeyama
authors.forename: M
authors.initials: M
authors.lastname: Saito
authors.forename: J
authors.initials: J
authors.lastname: Nakayama
authors.forename: R
authors.initials: R
authors.lastname: Nikaido
authors.forename: T
authors.initials: T
authors.lastname: Haruyama
authors.forename: Y
authors.initials: Y
authors.lastname: Watanabe
authors.forename: H
authors.initials: H
authors.lastname: Iwata
authors.forename: M
authors.initials: M
authors.lastname: Iida
authors.forename: H
authors.initials: H
authors.lastname: Sugimura
authors.forename: N
authors.initials: N
authors.lastname: Yamada
authors.forename: F
authors.initials: F
authors.lastname: Ishikawa
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D020134:Catalytic Domain / Q000235:genetics*; D002457:Cell Extracts; D004247:DNA / Q000032:analysis; D004268:DNA-Binding Proteins; D016521:Electrophoresis, Gel, Pulsed-Field; D006367:HeLa Cells; D006801:Humans; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008969:Molecular Sequence Data; D012313:RNA; D019098:Telomerase / Q000235:genetics* / Q000378:metabolism; D013737:Testis / Q000033:anatomy & histology
chemical_list: D002457:Cell Extracts; D004268:DNA-Binding Proteins; C422952:telomerase RNA; D012313:RNA; D004247:DNA; C509186:TERT protein, human; D019098:Telomerase; C509187:Tert protein, mouse