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Effect of PI3-kinase inhibitors on DNA double strand break repair pathways: observations using a site specific DSB

Tomoki Myodo1, Yuki Sakamoto1, Keita Sato1

  • 1Department of Biological Sciences, Ibaraki University, Bunkyo 2-1-1, Mito 310-8512, Ibaraki, Japan.

Radiation Protection Dosimetry
|November 14, 2024
PubMed

Insights

Inhibiting ATM kinase reduces DNA double-strand break (DSB) mutations and enhances homology-directed repair (HR). This suggests ATM kinase suppresses DSB end resection, favoring non-homologous end joining.

Area of Science:

  • Molecular Biology
  • Genetics
  • Biochemistry

Background:

  • DNA double-strand breaks (DSBs) are critical DNA lesions requiring efficient repair.
  • Homology-directed repair (HR) and non-homologous end joining (NHEJ) are major DSB repair pathways.
  • The role of Ataxia Telangiectasia Mutated (ATM) kinase in regulating DSB repair pathway choice is not fully understood.

Purpose of the Study:

  • To investigate the impact of ATM kinase activity on DSB repair efficiency and quality.
  • To elucidate the mechanisms by which ATM influences DSB repair pathway selection.

Main Methods:

  • Development of two site-specific DSB induction systems: one for mutation assays targeting the HPRT1 gene and another for HR reporter construct analysis.
  • Utilized zinc finger nucleases for targeted DSB generation.
  • Applied PI3-kinase inhibitors, specifically targeting ATM kinase, to assess their effects on DSB repair.

Main Results:

  • ATM kinase inhibition led to a decrease in mutant frequency.
  • Inhibition of ATM kinase resulted in a slight increase in deletion-type mutations associated with microhomology.
  • Homology-directed repair (HR) frequency significantly increased upon ATM kinase inhibition.

Conclusions:

  • ATM kinase activity appears to suppress DSB end resection.
  • Inhibition of ATM kinase may promote DSB repair through canonical non-homologous end joining (NHEJ).
  • These findings provide insights into the regulatory mechanisms governing DSB repair pathway choice.

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