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Purine DNA Lesions at Different Oxygen Concentration in DNA Repair-Impaired Human Cells (EUE-siXPA)

Marios G Krokidis1,2, Eleonora Parlanti3, Mariarosaria D'Errico4

  • 1Istituto per la Sintesi Organica e la Fotoreattività, Consiglio Nazionale delle Ricerche, Via P. Gobetti 101, 40129 Bologna, Italy. m.krokidis@inn.demokritos.gr.

Cells
|November 6, 2019
PubMed

Insights

Xeroderma Pigmentosum (XP) cells show altered DNA repair under varying oxygen levels, with significant increases in cyclopurine (cP) lesions under hypoxia. This study highlights the impact of oxygen on DNA damage and repair in XP cells.

Area of Science:

  • Molecular Biology
  • Genetics
  • Biochemistry

Background:

  • Xeroderma Pigmentosum (XP) is a DNA repair disease linked to nucleotide excision repair (NER) malfunction.
  • XP-A's role in NER is known, but discrepancies in reactive oxygen species (ROS) levels and radical species roles exist between normal and XP-A deficient cells.
  • Understanding DNA damage and repair mechanisms in XP is crucial for disease management.

Purpose of the Study:

  • To investigate the levels of specific DNA lesions, 5',8-cyclopurines (cPu) and 8-oxo-purines (8-oxo-Pu), in normal and XP-A deficient human cell lines.
  • To determine the influence of varying oxygen concentrations (hyperoxic, physioxic, hypoxic) on these DNA lesions.
  • To measure metal ion (Fe, Cu) levels and analyze membrane lipidomics in relation to DNA repair capacity.

Main Methods:

  • Liquid chromatography tandem mass spectrometry (LC-MS/MS) was used to quantify DNA lesions.
  • Analysis of four 5',8-cyclopurines (cPu) and two 8-oxo-purines (8-oxo-Pu) in wild-type (wt) and XP-A deficient (XPA-siXPA) cell lines.
  • Measurement of iron (Fe) and copper (Cu) levels, alongside membrane lipidomic analysis under different oxygen tensions.

Main Results:

  • Total cPu and 8-oxo-Pu levels were comparable in magnitude in both cell types.
  • 8-oxo-Pu levels increased across all conditions, while cPu levels remained stable under hyperoxic and physioxic conditions.
  • Hypoxia significantly increased cPu levels but decreased 8-oxo-Pu levels in both wt and deficient cells.
  • XP-A deficient cells exhibited significantly higher Fe levels.
  • Distinct fatty acid profiles were observed in wt versus deficient cells under normoxia.

Conclusions:

  • Oxygen concentration significantly impacts DNA lesion profiles in cells with differing DNA repair capabilities.
  • The study establishes a novel connection between oxygen levels, DNA repair deficiency, and specific DNA lesion accumulation, emphasizing the importance of cPu lesions.
  • Observed differences in membrane lipid composition suggest functional implications for membrane integrity and repair processes in XP cells.
Keywords:
XPA, DNA repair, hypoxia, oxidative lesions, hydroxyl radicals, oxygen concentration

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