Distinct ATRX functions cooperate with 9-1-1 and CST complexes to safeguard replication and telomere integrity

Area of Science:

• Genetics
• Molecular Biology
• Cell Biology

Background:

• Mutations in the ATRX chromatin remodeler are linked to developmental disorders and cancer.
• The precise mechanisms by which ATRX maintains genome and telomere stability are not fully understood.

Purpose of the Study:

• To elucidate the functional dependencies of ATRX-deficient cells on specific protein complexes.
• To investigate the role of ATRX in suppressing DNA damage during replication stress.
• To determine the separable functions of ATRX in telomere maintenance and replication.

Main Methods:

• Investigated synthetic lethality in ATRX-deficient cells using genetic screens.
• Analyzed telomere integrity and genome-wide single-stranded DNA (ssDNA) accumulation.
• Assessed the impact of ATRX mutations on DNA replication stress response.
• Utilized biochemical assays to examine ATRX ATPase activity and protein interactions.

Main Results:

• ATRX-deficient cells exhibit synthetic lethality with the CTC1-STN1-TEN1 (CST) complex due to telomeric G-rich ssDNA accumulation.
• ATRX-deficient cells show synthetic lethality with the RAD9A-HUS1-RAD1 (9-1-1) clamp, linked to genome-wide ssDNA lesions that impair DNA replication.
• ATRX suppresses replication-associated DNA damage by inhibiting FAM111A protease activity.
• ATRX's telomere maintenance and replication roles are genetically separable, dependent on its ATPase activity and PIP-box, respectively.
• These genome stability functions are largely independent of the ATRX-DAXX interaction.

Conclusions:

• ATRX functions are context-dependent in suppressing toxic ssDNA lesions.
• ATRX is critical for both global DNA replication and telomere integrity.
• Understanding ATRX dependencies offers insights into therapeutic strategies for ATRX-mutated cancers and genetic disorders.