Effects of hydroxyurea and aphidicolin on phosphorylation of ataxia telangiectasia mutated on Ser 1981 and histone H2AX on Ser 139 in relation to cell cycle phase and induction of apoptosis
Abstract
DNA replication stress often induces DNA damage. The antitumor drug hydroxyurea (HU), a potent inhibitor of ribonucleotide reductase that halts DNA replication through its effects on cellular deoxynucleotide pools, was shown to damage DNA inducing double-strand breaks (DSBs). Aphidicolin (APH), an inhibitor of alpha-like DNA polymerases, was also reported to cause DNA damage, but the evidence for induction of DSBs by APH is not straightforward. Histone H2AX is phosphorylated on Ser 139 in response to DSBs and one of the protein kinases that phosphorylate H2AX is ataxia telangiectasia mutated (ATM); activation of ATM is through its phosphorylation of Ser 1981. The present study was undertaken to reveal whether H2AX is phosphorylated in cells exposed to HU or APH and whether its phosphorylation is mediated by ATM. HL-60 cells were treated in cultures with 0.1-5.0 mM HU or 1-4 muM APH for up to 5 h. Activation of ATM and H2AX phosphorylation was detected immunocytochemically using Ab specific to Ser1981-ATM or Ser 139-H2AX epitopes, respectively, concurrent with measurement of cellular DNA content. While exposure of cells to HU led to H2AX phosphorylation selectively during S phase and the cells progressing through the early porti...Continue Reading
References
Comparison of checkpoint responses triggered by DNA polymerase inhibition versus DNA damaging agents
Citations
ATM activation accompanies histone H2AX phosphorylation in A549 cells upon exposure to tobacco smoke
Impaired DNA damage response--an Achilles' heel sensitizing cancer to chemotherapy and radiotherapy.
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Ataxia telangiectasia
Ataxia telangiectasia is a rare neurodegenerative diseases caused by defects in the ATM gene, which is involved in DNA damage recognition and repair pathways. Here is the latest research on this autosomal recessive disease.
Ataxia telangiectasia (MDS)
Ataxia telangiectasia is a rare neurodegenerative diseases caused by defects in the ATM gene, which is involved in DNA damage recognition and repair pathways. Here is the latest research on this autosomal recessive disease.
Apoptosis
Apoptosis is a specific process that leads to programmed cell death through the activation of an evolutionary conserved intracellular pathway leading to pathognomic cellular changes distinct from cellular necrosis