Fused in sarcoma regulates DNA replication timing and kinetics

Area of Science:

• Molecular Biology
• Genetics
• Cell Biology

Background:

• Fused in sarcoma (FUS) is an RNA-binding protein involved in transcription, splicing, and genome maintenance.
• Mutations in FUS are linked to diseases like amyotrophic lateral sclerosis and sarcomas.
• The precise mechanisms by which FUS influences genome stability remain unclear.

Purpose of the Study:

• To elucidate the roles of FUS in DNA replication and repair processes.
• To understand how FUS contributes to genome stability.
• To investigate the impact of FUS deficiency on cellular functions related to DNA replication.

Main Methods:

• Gene editing (CRISPR-Cas9) to create FUS-deficient cells.
• Functional reconstitution experiments.
• Integrated proteomics and transcriptomics analysis.
• Assessment of DNA double-strand break repair factor recruitment.
• Analysis of replication fork progression, prereplication complex loading, and micronucleus formation.
• DNA replication timing assays.

Main Results:

• FUS-deficient cells showed subtle defects in DNA double-strand break repair factor recruitment (e.g., 53BP1, BRCA1).
• Loss of FUS reduced cellular proliferative potential, slowed replication fork progression, diminished prereplication complex loading, and increased micronucleus formation.
• FUS deficiency led to altered expression and splicing of S-phase genes and genome-wide changes in DNA replication timing.
• FUS is required for timely replication of transcriptionally active DNA, particularly in active chromatin domains.

Conclusions:

• FUS plays a critical role in supporting DNA replication fidelity and genome stability.
• Alterations in DNA replication kinetics and programming due to FUS deficiency contribute to genome instability and cellular dysfunction.
• These findings highlight FUS as a key regulator of DNA replication timing and genome maintenance.