The BRCA1 coiled-coil domain is dispensable for suppression of tandem duplications and tolerance of FANCM loss.

Brca1 coiled-coil domain mutants retain the ability to suppress Group 1 tandem duplications in mouse cells and tumor models despite impaired homologous recombination functions.

• Why it matters: Understanding how BRCA1 suppresses tandem duplications is crucial because these duplications are abundant in BRCA1-linked cancers, and current knowledge about the specific domains involved remains incomplete.
• What they did: Researchers analyzed Brca1 coiled-coil domain mutants that are impaired for homologous recombination but still capable of DNA-end resection, assessing their ability to suppress tandem duplications in mouse embryonic stem cells and tumor models.
• The result: The findings show that Brca1 CC mutants can still suppress tandem duplications, indicating that this suppression is independent of homologous recombination functions, and Fancm deletion differentially affects cell growth depending on Brca1 mutation status.