The Compromised Fanconi Anemia Pathway in Prelamin A-Expressing Cells Contributes to Replication Stress-Induced...

Area of Science:

• Cellular Biology
• Genetics
• Molecular Biology

Background:

• Genomic instability is a hallmark of cellular senescence, often driven by replication stress.
• Defects in prelamin A processing due to LMNA or ZMPSTE24 mutations cause premature aging syndromes.
• The precise link between lamin A dysfunction and replication stress is not fully understood.

Purpose of the Study:

• To investigate the relationship between prelamin A accumulation and replication stress-induced genomic instability.
• To elucidate the molecular mechanisms by which prelamin A affects DNA replication and repair pathways.

Main Methods:

• Analysis of baseline replication stress and genomic instability in cells expressing prelamin A.
• Assessment of cell survival and genomic instability under exogenous replication stress.
• Investigation of prelamin A's effect on MRE11-mediated fork resection and Fanconi anemia (FA) pathway components.
• Evaluation of the FA pathway's activation and its relationship with the p53-p21 axis.

Main Results:

• Prelamin A expression increases baseline replication stress and genomic instability.
• Cells with prelamin A exhibit hypersensitivity to exogenous replication stress, leading to reduced survival and increased genomic instability.
• Prelamin A promotes MRE11-dependent resection of stalled replication forks and downregulates Fanconi anemia proteins in an RB/E2F-dependent manner.
• Prelamin A inhibits FA pathway activation and FA pathway downregulation precedes p53-p21 activation.

Conclusions:

• Prelamin A accumulation exacerbates replication stress and genomic instability.
• Dysfunction of the Fanconi anemia pathway is a critical mediator of replication stress-induced genomic instability and cellular senescence in prelamin A-expressing cells.
• These findings offer insights into the pathogenesis of premature aging disorders linked to lamin A/C defects.