Separation of telomerase functions by reverse genetics

Proc Natl Acad Sci U S A. 2011 Dec 13;108(50):E1363-71. doi: 10.1073/pnas.1112414108. Epub 2011 Sep 26.

Abstract

The canonical function of the human telomerase protein (hTERT) is to synthesize telomeric DNA, but it has other biological activities, including enhancing cell proliferation, decreasing apoptosis, regulating DNA damage responses, and increasing cellular proliferative lifespan. The mechanistic relationships among these activities are not understood. We previously demonstrated that ectopic hTERT expression in primary human mammary epithelial cells diminishes their requirement for exogenous mitogens, thus giving them a proliferative advantage in a mitogen-depleted environment. Here, we show that this phenotype is caused by a combination of increased cell division and decreased apoptosis. In addition, we use a panel of hTERT mutants to demonstrate that this enhanced cell proliferation can be uncoupled not only from telomere elongation, but also from other telomerase activities, including cellular lifespan extension and regulation of DNA damage responses. We also find that the proliferative function of hTERT, which requires hTERT catalytic activity, is not caused by increased Wnt signaling, but is accompanied by alterations in key cell cycle regulators and is linked to an hTERT-catalyzed decrease in the levels of the RNA component of mitochondrial RNA processing endoribonuclease. Thus, enhanced cell proliferation is an independent function of hTERT that could provide a new target for the development of anti-telomerase cancer therapeutic agents.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Biocatalysis / drug effects
  • Breast / cytology
  • Cell Division / drug effects
  • Cell Proliferation / drug effects
  • Cell Survival / drug effects
  • Cellular Senescence / drug effects
  • Chromosomal Instability / drug effects
  • DNA Damage
  • Endoribonucleases / metabolism
  • Epithelial Cells / cytology
  • Epithelial Cells / drug effects
  • Epithelial Cells / enzymology
  • Female
  • Humans
  • Mice
  • Mitogens / pharmacology
  • Reverse Genetics*
  • Telomerase / genetics*
  • Telomerase / metabolism*
  • Telomere / metabolism
  • Wnt Signaling Pathway / drug effects

Substances

  • Mitogens
  • TERT protein, human
  • Telomerase
  • Endoribonucleases
  • mitochondrial RNA-processing endoribonuclease