Interaction of BARD1 and HP1 Is Required for BRCA1 Retention at Sites of DNA Damage.

Abstract

Stable retention of BRCA1/BARD1 complexes at sites of DNA damage is required for the proper response to DNA double-strand breaks (DSB). Here, we demonstrate that the BRCT domain of BARD1 is crucial for its retention through interaction with HP1. In response to DNA damage, BARD1 interacts with Lys9-dimethylated histone H3 (H3K9me2) in an ATM-dependent but RNF168-independent manner. This interaction is mediated primarily by HP1γ. A conserved HP1-binding motif in the BARD1 BRCT domain directly interacted with the chromoshadow domain of HP1 in vitro. Mutations in this motif (or simultaneous depletion of all three HP1 isoforms) disrupted retention of BARD1, BRCA1, and CtIP at DSB sites and allowed ectopic accumulation of RIF1, an effector of nonhomologous end-joining, at damaged loci in S-phase. UNC0638, a small-molecule inhibitor of histone lysine methyltransferase (HKMT), abolished retention and cooperated with the PARP inhibitor olaparib to block cancer cell growth. Taken together, our findings show how BARD1 promotes retention of the BRCA1/BARD1 complex at damaged DNA sites and suggest the use of HKMT inhibitors to leverage the application of PARP inhibitors to treat breast cancer.

• Authors: Wenwen Wu, Hiroyuki Nishikawa, Takayo Fukuda, Vinayak Vittal, Masahide Asano, Yasuo Miyoshi, Rachel E Klevit, Tomohiko Ohta
• Journal: Cancer research (Cancer Res) Vol. 75 Issue 7 Pg. 1311-21 (Apr 01 2015) ISSN: 1538-7445 [Electronic] United States
• PMID: 25634209 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)
• Copyright: ©2015 American Association for Cancer Research.

Chemical References

• BRCA1 Protein
• BRCA1 protein, human
• Chromosomal Proteins, Non-Histone
• Histones
• Tumor Suppressor Proteins
• Chromobox Protein Homolog 5
• BARD1 protein, human
• Ubiquitin-Protein Ligases

Topics

• Amino Acid Motifs
• BRCA1 Protein (metabolism)
• Cell Line, Tumor
• Chromobox Protein Homolog 5
• Chromosomal Proteins, Non-Histone (metabolism)
• DNA Damage
• DNA Repair
• HEK293 Cells
• Histones
• Humans
• Protein Interaction Domains and Motifs
• Protein Transport
• Tumor Suppressor Proteins (metabolism)
• Ubiquitin-Protein Ligases (metabolism)