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Overcoming Pluripotent Stem Cell Dependence on the Repair of Endogenous DNA Damage

Timothy M Chlon1, Sonya Ruiz-Torres1, Logan Maag1

  • 1Cancer and Blood Diseases Institute, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, MLC-7013, Cincinnati, OH 45229, USA.

Stem Cell Reports
|January 16, 2016
PubMed

Insights

Pluripotent stem cells (PSCs) use error-free DNA repair pathways. Loss of the Fanconi anemia (FA) pathway in PSCs causes DNA damage and cell death, but CHK1 inhibition rescues growth.

Area of Science:

  • Stem cell biology
  • DNA repair mechanisms
  • Genetics

Background:

  • Pluripotent stem cells (PSCs) exhibit low mutation rates, partly due to efficient homologous recombination (HR) for DNA repair.
  • Endogenous metabolites can cause DNA interstrand crosslinks, which are repaired by the Fanconi anemia (FA) pathway, a HR-dependent process.

Purpose of the Study:

  • To investigate the impact of impaired DNA repair on PSC biology.
  • To understand the role of the Fanconi anemia (FA) pathway in maintaining genomic stability in PSCs.

Main Methods:

  • Generation of induced pluripotent stem cells (iPSCs) with a conditional FA pathway.
  • Analysis of cell cycle arrest, apoptosis, and DNA damage markers (γH2AX, RAD51) in FA-deficient iPSCs.
  • Assessment of DNA damage signaling pathways, including CHK1 activation.
  • Evaluation of CHK1 inhibition on the proliferation and genomic stability of FA-deficient iPSCs.

Main Results:

  • Loss of the FA pathway in iPSCs led to significant G2 arrest and apoptosis, while parental fibroblasts remained unaffected.
  • FA-deficient iPSCs accumulated substantial DNA damage, evidenced by large γH2AX-RAD51 foci and activated CHK1 signaling.
  • Inhibition of CHK1 rescued the growth of FA-deficient iPSCs during extended culture without inducing major karyotypic abnormalities.

Conclusions:

  • PSCs possess hyperactive CHK1 signaling that limits self-renewal when error-free DNA repair is compromised.
  • The FA pathway is crucial for preventing DNA damage accumulation and maintaining viability in pluripotent stem cells.
  • Targeting CHK1 may offer a therapeutic strategy to support the culture of stem cells with defective DNA repair mechanisms.

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