Caffeine impairs resection during DNA break repair by reducing the levels of nucleases Sae2 and Dna2.
Nucleic Acids Res
; 43(14): 6889-901, 2015 Aug 18.
Article
em En
| MEDLINE
| ID: mdl-26019182
ABSTRACT
In response to chromosomal double-strand breaks (DSBs), eukaryotic cells activate the DNA damage checkpoint, which is orchestrated by the PI3 kinase-like protein kinases ATR and ATM (Mec1 and Tel1 in budding yeast). Following DSB formation, Mec1 and Tel1 phosphorylate histone H2A on serine 129 (known as γ-H2AX). We used caffeine to inhibit the checkpoint kinases after DSB induction. We show that prolonged phosphorylation of H2A-S129 does not require continuous Mec1 and Tel1 activity. Unexpectedly, caffeine treatment impaired homologous recombination by inhibiting 5' to 3' end resection, independent of Mec1 and Tel1 inhibition. Caffeine treatment led to the rapid loss, by proteasomal degradation, of both Sae2, a nuclease that plays a role in early steps of resection, and Dna2, a nuclease that facilitates one of two extensive resection pathways. Sae2's instability is evident in the absence of DNA damage. A similar loss is seen when protein synthesis is inhibited by cycloheximide. Caffeine treatment had similar effects on irradiated HeLa cells, blocking the formation of RPA and Rad51 foci that depend on 5' to 3' resection of broken chromosome ends. Our findings provide insight toward the use of caffeine as a DNA damage-sensitizing agent in cancer cells.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Cafeína
/
DNA Helicases
/
Proteínas de Saccharomyces cerevisiae
/
Reparo do DNA
/
Endonucleases
/
Quebras de DNA de Cadeia Dupla
Limite:
Humans
Idioma:
En
Revista:
Nucleic Acids Res
Ano de publicação:
2015
Tipo de documento:
Article