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Detection and Visualization of DNA Damage-induced Protein Complexes in Suspension Cell Cultures Using the Proximity Ligation Assay
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Detection and Visualization of DNA Damage-induced Protein Complexes in Suspension Cell Cultures Using the Proximity Ligation Assay

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S-phase sensing of DNA-protein crosslinks triggers TopBP1-independent ATR activation and p53-mediated cell death by

Victor Chun-Lam Wong1, Haley L Cash, Jessica L Morse

  • 1Department of Pathology and Laboratory Medicine, Brown University, Providence, RI, USA.

Cell Cycle (Georgetown, Tex.)
|June 23, 2012
PubMed

Insights

Formaldehyde (FA) causes DNA-protein crosslinks (DPCs), activating ATR-p53 signaling in S-phase cells. This noncanonical response, independent of DNA repair, dictates cell fate and has implications for FA carcinogenesis.

Area of Science:

  • Cellular biology
  • Molecular toxicology
  • DNA damage response

Background:

  • DNA-protein crosslinks (DPCs) are lesions formed by carcinogens like formaldehyde (FA).
  • The cellular response to DPCs, particularly formaldehyde-induced DPCs, is not well understood.
  • Understanding genotoxic signaling pathways is crucial for cancer research.

Purpose of the Study:

  • To investigate the genotoxic signaling and cell fate decisions induced by formaldehyde (FA).
  • To elucidate the mechanism of ATR kinase activation and p53 signaling in response to FA-induced DNA-protein crosslinks (DPCs).
  • To explore the implications of this response in formaldehyde carcinogenesis.

Main Methods:

  • Human cell treatment with formaldehyde.
  • Analysis of ATR kinase and CHK1 kinase activation via phosphorylation.
  • Assessment of p53 accumulation and phosphorylation at Ser15.
  • Investigation of DNA repair pathway involvement (MMR, BER, NER).
  • Cell cycle analysis and characterization of S-phase specific responses.
  • Analysis of ATR foci, TopBP1 independence, and MCM helicase interactions.
  • Cell fate determination assays (apoptosis, senescence).

Main Results:

  • Formaldehyde rapidly activates ATR kinase, targeting p53 at low doses and CHK1 at higher doses.
  • p53 activation is transcription-independent, S-phase specific, and not reliant on canonical DNA repair pathways.
  • Formaldehyde-induced DPCs trigger a noncanonical ATR activation, independent of TopBP1 and RPA/RAD1 foci.
  • Replication arrest is linked to MCM helicase dissociation, not stalled polymerases (PCNA monoubiquitination).
  • FA-activated p53 promotes apoptosis in lung epithelial cells and senescence in lung fibroblasts.

Conclusions:

  • S-phase-specific, TopBP1-independent ATR-p53 axis activation is a critical response to FA-DPCs.
  • The mechanism involves blocking MCM helicase, preventing ssDNA accumulation, unlike typical DNA adducts.
  • This distinct genotoxic signaling pathway has significant implications for understanding formaldehyde-induced carcinogenesis.

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