Telomerase Maintains Telomere Structure in Normal Human Cells

Cell. 2003 Jul 25;114(2):241-53. doi: 10.1016/s0092-8674(03)00550-6.

Abstract

In normal human cells, telomeres shorten with successive rounds of cell division, and immortalization correlates with stabilization of telomere length. These observations suggest that human cancer cells achieve immortalization in large part through the illegitimate activation of telomerase expression. Here, we demonstrate that the rate-limiting telomerase catalytic subunit hTERT is expressed in cycling primary presenescent human fibroblasts, previously believed to lack hTERT expression and telomerase activity. Disruption of telomerase activity in normal human cells slows cell proliferation, restricts cell lifespan, and alters the maintenance of the 3' single-stranded telomeric overhang without changing the rate of overall telomere shortening. Together, these observations support the view that telomerase and telomere structure are dynamically regulated in normal human cells and that telomere length alone is unlikely to trigger entry into replicative senescence.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Antibodies, Monoclonal / metabolism
  • Cell Nucleus / metabolism
  • Cell Transformation, Viral / genetics
  • DNA Replication
  • Enzyme Activation
  • Fibroblasts / cytology
  • Fibroblasts / enzymology
  • Fibroblasts / metabolism
  • HeLa Cells
  • Humans
  • Kinetics
  • Models, Biological
  • Mutation
  • Proliferating Cell Nuclear Antigen / metabolism
  • RNA, Messenger / metabolism
  • RNA, Small Interfering / metabolism
  • Retroviridae / genetics
  • Telomerase / genetics
  • Telomerase / immunology
  • Telomerase / metabolism*
  • Telomere / genetics
  • Telomere / metabolism*
  • Tumor Cells, Cultured

Substances

  • Antibodies, Monoclonal
  • Proliferating Cell Nuclear Antigen
  • RNA, Messenger
  • RNA, Small Interfering
  • Telomerase