The CST complex facilitates cell survival under oxidative genotoxic stress

Area of Science:

• Molecular Biology
• Genetics
• Cell Biology

Background:

• Genomic DNA integrity is vital, requiring robust repair mechanisms against genotoxic stress.
• The CTC1-STN1-TEN1 (CST) complex, known for telomere maintenance, is implicated in DNA replication stress response.
• The role of the CST complex in repairing oxidative DNA damage remained largely uncharacterized.

Purpose of the Study:

• To investigate the involvement of the CST complex in repairing oxidative DNA damage induced by hydrogen peroxide (H2O2).
• To elucidate the specific cellular and molecular mechanisms by which the CST complex contributes to genomic stability under oxidative stress.

Main Methods:

• Utilized STN1 knockdown (KD) in HeLa cells to assess sensitivity to H2O2.
• Analyzed DNA strand breaks, DNA synthesis, and RAD51 foci formation across the cell cycle.
• Investigated the interplay between the CST complex and RAD51 in DNA repair pathways.

Main Results:

• STN1 KD sensitized cells to H2O2, with sensitivity pronounced in S/G2/M phases but not G1.
• H2O2 treatment in STN1 KD cells led to impaired DNA synthesis and RAD51 foci formation.
• RAD51 inhibition did not worsen H2O2 sensitivity in STN1 KD cells, suggesting a shared pathway.

Conclusions:

• The CST complex is essential for maintaining genomic stability against oxidative DNA damage.
• The CST complex likely functions through RAD51-dependent DNA repair and protection mechanisms.
• These findings highlight a novel role for the CST complex in cellular defense against oxidative stress.