ATRX cooperates with TOP2B for replication fork stability and DNA damage response through G-quadruplex regulation

Area of Science:

• Genetics
• Molecular Biology
• Oncology

Background:

• G-quadruplexes (G4s) are noncanonical DNA structures linked to genomic instability in ATRX-deficient gliomas.
• The role of TOP2B in G4 resolution and its interaction with ATRX are not well understood.

Purpose of the Study:

• To identify TOP2B as a regulator of G4 homeostasis.
• To investigate the cooperative role of TOP2B and ATRX in G4 resolution during DNA replication.
• To elucidate the mechanism of CX-5461 in disrupting G4 resolution and inducing DNA damage.

Main Methods:

• Investigated TOP2B's role in G4 homeostasis using molecular biology techniques.
• Examined the functional cooperation between TOP2B and ATRX in G4 resolution.
• Analyzed the effects of CX-5461 on G4 accumulation, replication stress, and DNA damage in glioma cells.
• Compared CX-5461's mechanism with etoposide.

Main Results:

• TOP2B was identified as a novel regulator of G4 homeostasis, cooperating with ATRX to resolve G4s during replication.
• CX-5461 disrupts the ATRX-TOP2B pathway, leading to G4 accumulation, replication stress, and DNA damage.
• CX-5461 acts as a TOP2B poison, impairing TOP2B binding at G4 sites and altering replication fork dynamics.
• These effects are amplified in ATRX-deficient glioma cells, highlighting TOP2B's critical role.

Conclusions:

• TOP2B is a key player in G4 resolution, working with ATRX to maintain genomic stability.
• CX-5461 exhibits a unique dual function as a TOP2B poison and G4 stabilizer.
• G4-associated replication stress presents a potential therapeutic target for ATRX-deficient gliomas.