 chromatin compaction represents a barrier for the repair of dna double - strand breaks ( dsbs ) . 
 however , heterochromatin components are also required for dsb repair by homologous recombination . 
 the bard1/hp1 interaction , required for the retention of brca1 , ctip , and rad51 at dsb sites , may play a critical role in the crosstalk between chromatin compaction and dsb repair . 
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