Caenorhabditis elegans POT-1 and POT-2 repress telomere maintenance pathways

G3 (Bethesda). 2013 Feb;3(2):305-13. doi: 10.1534/g3.112.004440. Epub 2013 Feb 1.

Abstract

Telomeres are composed of simple tandem DNA repeats that protect the ends of linear chromosomes from replicative erosion or inappropriate DNA damage response mechanisms. The mammalian Protection Of Telomeres (POT1) protein interacts with single-stranded telomeric DNA and can exert positive and negative effects on telomere length. Of four distinct POT1 homologs in the roundworm Caenorhabditis elegans, deficiency for POT-1 or POT-2 resulted in progressive telomere elongation that occurred because both proteins negatively regulate telomerase. We created a POT-1::mCherry fusion protein that forms discrete foci at C. elegans telomeres, independent of POT-2, allowing for live analysis of telomere dynamics. Transgenic pot-1::mCherry repressed telomerase in pot-1 mutants. Animals deficient for pot-1, but not pot-2, displayed mildly enhanced telomere erosion rates in the absence of the telomerase reverse transcriptase, trt-1. However, trt-1; pot-1 double mutants exhibited delayed senescence in comparison to trt-1 animals, and senescence was further delayed in trt-1; pot-2; pot-1 triple mutants, some of which survived robustly in the absence of telomerase. Our results indicate that POT-1 and POT-2 play independent roles in suppressing a telomerase-independent telomere maintenance pathway but may function together to repress telomerase.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Aging
  • Animals
  • Caenorhabditis elegans / genetics
  • Caenorhabditis elegans / metabolism*
  • Caenorhabditis elegans Proteins / genetics
  • Caenorhabditis elegans Proteins / metabolism*
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism*
  • Luminescent Proteins / genetics
  • Luminescent Proteins / metabolism
  • Mutation
  • Recombinant Fusion Proteins / biosynthesis
  • Recombinant Fusion Proteins / genetics
  • Red Fluorescent Protein
  • Telomerase / genetics
  • Telomerase / metabolism
  • Telomere / metabolism*
  • Telomere-Binding Proteins / genetics
  • Telomere-Binding Proteins / metabolism*

Substances

  • Caenorhabditis elegans Proteins
  • DNA-Binding Proteins
  • Luminescent Proteins
  • POT-1 protein, C elegans
  • POT-2 protein, C elegans
  • Recombinant Fusion Proteins
  • Telomere-Binding Proteins
  • Telomerase