PRPF8 is important for BRCA1-mediated homologous recombination

Area of Science:

• Molecular Biology
• Cancer Research
• Genetics

Background:

• RNA splicing alterations can lead to genome instability and cancer.
• RNA splicing is a promising target for anti-cancer therapies.
• Homologous recombination (HR) is a critical DNA repair pathway frequently disrupted in cancer.

Purpose of the Study:

• To investigate the impact of the spliceosome factor PRPF8 and the splicing inhibitor Pladienolide B (PlaB) on homologous recombination (HR).
• To elucidate the specific DNA repair pathways affected by PRPF8 depletion and PlaB treatment.
• To differentiate the mechanisms of action between PRPF8 depletion and PlaB treatment on DNA damage response.

Main Methods:

• Assessed homology-directed repair (HDR) and single-strand annealing (SSA) in cells with PRPF8 depletion or PlaB treatment.
• Quantified end resection by measuring chromatin-bound RPA and BRCA1 foci formation.
• Analyzed histone acetylation marks, 53BP1 foci, BRCA1 expression, and interchromatin granule integrity.

Main Results:

• Both PRPF8 depletion and PlaB treatment specifically impaired HDR and SSA, dependent on end resection and BRCA1.
• Reduced end resection, BRCA1 foci, and associated histone acetylation were observed in both conditions.
• PlaB uniquely reduced 53BP1 foci and BRCA1 expression, and disrupted nuclear organization, unlike PRPF8 depletion.

Conclusions:

• PRPF8 plays a significant role in BRCA1-mediated HR DNA repair.
• PlaB exhibits broader effects on DNA damage response and nuclear organization beyond HR.
• These findings highlight distinct roles of splicing factors and inhibitors in maintaining genome stability and suggest potential therapeutic strategies.