MYC impairs resolution of site-specific DNA double-strand breaks repair

Area of Science:

• Molecular Biology
• Genetics
• Cell Biology

Background:

• Overexpression of MYC family proteins is linked to DNA double-strand breaks (DSBs) and genome instability.
• The precise mechanisms by which MYC contributes to genetic instability, whether through increased DNA damage or impaired DNA repair, are not fully understood.

Purpose of the Study:

• To investigate the role of MYC proteins in the DNA damage response and repair of DSBs.
• To elucidate whether MYC overexpression affects DNA damage recognition or repair efficiency.

Main Methods:

• Utilized a cell-based system generating hundreds of site-specific DSBs genome-wide upon induction of the restriction enzyme AsiSI.
• Monitored the accumulation and clearance of γH2AX, a marker of DNA damage, at DSB sites.
• Assessed the recruitment of RAD51 to homologous and nonhomologous repair-prone segments to evaluate repair pathway involvement.

Main Results:

• High MYC levels did not impede the initial accumulation of γH2AX at DSB sites, indicating that DNA damage recognition was largely unaffected.
• A delay in the clearance of γH2AX was observed, suggesting inefficient repair of DSBs.
• The repair of both homologous recombination- (high RAD51) and nonhomologous end-joining- (low RAD51) prone DNA segments was delayed.

Conclusions:

• Overexpressed MYC proteins induce a sustained DNA damage response (DDR).
• High MYC levels impair the resolution and repair of DNA double-strand breaks.
• These findings suggest that delayed DSB repair contributes to MYC-induced genome instability.