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Dysfunctional telomeres activate an ATM-ATR-dependent DNA damage response to suppress tumorigenesis

Xiaolan Guo1, Yibin Deng, Yahong Lin

  • 1Department of Cancer Genetics, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.

The EMBO Journal
|October 20, 2007
PubMed

Insights

The POT1 protein protects telomeres, and TPP1 recruits POT1 to telomeres. Loss of TPP1 triggers an ATR-dependent DNA damage response, promoting instability and cancer.

Area of Science:

  • Molecular Biology
  • Genetics
  • Cancer Research

Background:

  • POT1 (protection of telomeres) protein binds G-rich overhangs, crucial for telomere protection and length regulation.
  • TPP1 enhances POT1's telomeric binding and function.

Purpose of the Study:

  • To investigate the role of mouse Tpp1 in telomere end protection.
  • To elucidate the DNA damage response pathways activated by Tpp1 depletion.
  • To understand the link between telomere dysfunction, chromosomal instability, and tumorigenesis.

Main Methods:

  • Investigated Tpp1's role in recruiting Pot1a and Pot1b to telomeres.
  • Utilized knockdown of Tpp1 to induce cellular responses.
  • Analyzed p53-dependent growth arrest and ATM/ATR-dependent DNA damage responses (DDR) at telomeres.
  • Assessed chromosomal instability and tumorigenesis in Tpp1-depleted cells.

Main Results:

  • Mouse Tpp1 recruits Pot1a and Pot1b to telomeres, conferring end protection.
  • Tpp1 knockdown induces p53-dependent growth arrest and an ATM-dependent DDR.
  • Removal of Pot1a/Pot1b from telomeres triggers an ATR-dependent DDR, distinct from Trf2 depletion.
  • Telomere dysfunction from Tpp1 depletion promotes chromosomal instability and tumorigenesis, even without ATM-dependent DDR.

Conclusions:

  • Uncovered a novel ATR-dependent DDR at telomeres, normally shielded by POT1.
  • Suggests loss of ATM cooperates with dysfunctional telomeres in cellular transformation and tumor formation.
  • Highlights TPP1's critical role in maintaining telomere integrity and preventing cancer.

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