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The mre11 complex and the response to dysfunctional telomeres

Claire L Attwooll1, Müge Akpinar, John H J Petrini

  • 1Laboratory of Chromosome Biology, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, RRL 901C Box 474, New York, NY 10021, USA.

Molecular and Cellular Biology
|August 12, 2009
PubMed

Insights

The Mre11 complex plays a role in managing telomere dysfunction and DNA damage. Studies using Mre11 and Nbs1 mutants show impaired responses to telomere damage and reduced telomere fusions.

Area of Science:

  • Molecular Biology
  • Genetics
  • Cell Biology

Background:

  • The Mre11 complex is crucial for DNA repair pathways, including those responding to DNA double-strand breaks.
  • Telomeres, the protective caps of chromosomes, are susceptible to dysfunction and damage, impacting genomic stability.
  • Understanding the role of DNA repair complexes at telomeres is essential for comprehending genome maintenance.

Purpose of the Study:

  • To investigate the telomeric functions of the mammalian Mre11 complex.
  • To determine the impact of Mre11 and Nbs1 hypomorphic mutations on telomere length, fusions, and response to acute telomere dysfunction.
  • To elucidate the role of the Mre11 complex in telomeric DNA end processing during replication.

Main Methods:

  • Utilized hypomorphic mutants of Mre11 (Mre11(ATLD1/ATLD1)) and Nbs1 (Nbs1(Delta)(B/)(DeltaB)).
  • Assessed telomere length and fusions in cultured cells, including telomerase-deficient (Tert(Delta)(/)(Delta)) cells.
  • Induced acute telomere dysfunction by creating Trf2-deficient cells (Trf2 inactivation) and analyzed DNA damage foci formation.

Main Results:

  • Mre11 complex mutants did not exhibit telomere shortening and showed reduced telomere fusions, even under conditions of acute telomere dysfunction.
  • Residual telomere fusions in Mre11 complex mutants predominantly involved chromatid fusions and preferentially occurred at leading-strand replicated telomeres.
  • The cellular response to acute telomere dysfunction, marked by DNA damage foci formation, was significantly impaired in Mre11 complex hypomorphic cells.

Conclusions:

  • The Mre11 complex influences the cellular response to telomere dysfunction, similar to its role at interstitial DNA breaks.
  • Mre11 complex hypomorphism impairs the response to acute telomere dysfunction.
  • The Mre11 complex may be involved in processing telomeric DNA ends during DNA replication.

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