Nucleolar protein nucleolin functions in replication stress-induced DNA damage responses

Area of Science:

• Molecular Biology
• Genetics
• Cell Biology

Background:

• The nucleolus contains ribosomal DNA (rDNA), a site prone to replication stress.
• Replication stress can lead to genomic instability.
• Nucleolin, a nucleolar protein, is involved in DNA damage response (DDR).

Purpose of the Study:

• To investigate the role of nucleolin in DDR induced by replication stress.
• To understand nucleolin's involvement in maintaining genomic stability against replication stress.

Main Methods:

• Investigated nucleolin's interaction with DNA damage markers (γH2AX, PCNA, RPA32) after replication stress.
• Utilized siRNA to knockdown nucleolin expression.
• Assessed the impact of nucleolin manipulation on ATR kinase activation and RAD51/RPA32 foci formation.
• Examined cell resistance to replication stress.

Main Results:

• Nucleolin interacts with key proteins at DNA damage sites during replication stress.
• Nucleolin knockdown impairs ATR activation and RAD51/RPA32 foci formation.
• Nucleolin overexpression enhances ATR-dependent phosphorylation and RAD51/RPA accumulation.
• Cells overexpressing nucleolin show increased repair activity and resistance to replication stress.

Conclusions:

• Nucleolin is crucial for replication stress-induced DDR, including ATR activation and homologous recombination (HR) repair.
• Nucleolin's role in resistance to replication stress may be relevant to tumorigenesis, as it's often overexpressed in cancer.
• Nucleolin represents a potential therapeutic target for cancer treatment, particularly in conjunction with chemotherapy and radiotherapy.