Removal of shelterin reveals the telomere end-protection problem.
The telomere end-protection problem is defined by the aggregate of DNA damage signaling and repair pathways that require repression at telomeres. To define the end-protection problem, we removed the whole shelterin complex from mouse telomeres through conditional deletion of TRF1 and TRF2 in nonhomologous end-joining (NHEJ) deficient cells. The data reveal two DNA damage response pathways not previously observed upon deletion of individual shelterin proteins. The shelterin-free telomeres are processed by microhomology-mediated alternative-NHEJ when Ku70/80 is absent and are attacked by nucleolytic degradation in the absence of 53BP1. The data establish that the end-protection problem is specified by six pathways [ATM (ataxia telangiectasia mutated) and ATR (ataxia telangiectasia and Rad3 related) signaling, classical-NHEJ, alt-NHEJ, homologous recombination, and resection] and show how shelterin acts with general DNA damage response factors to solve this problem.
Laboratory for Cell Biology and Genetics, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA.
SourceScience (New York, N.Y.) 336:6081 2012 May 4 pg 593-7
Ataxia Telangiectasia Mutated Proteins
Cell Cycle Proteins
Chromosomal Proteins, Non-Histone
DNA Breaks, Double-Stranded
DNA End-Joining Repair
Telomeric Repeat Binding Protein 1
Telomeric Repeat Binding Protein 2
Tumor Suppressor Proteins
Pub Type(s)Journal Article
Research Support, N.I.H., Extramural