H3K9me3 asymmetry: epigenetic choreography in DNA replication for genomic stability

Abstract

Parental histones, which are modified distinctively from their newly synthesized counterparts, are recycled during DNA replication for the re-establishment of a functional epigenome in the daughter cells. However, the mechanisms and functional implications underlying parental histone deposition onto replicating DNA strands remain enigmatic. A recent study published in Nature reveals a unique pattern of H3K9me3 distribution during DNA replication, which is governed by the human silencing hub (HUSH) complex and DNA polymerase Pol ε. H3K9me3 asymmetry toward the leading strand is important for the silencing of L1 retrotransposons, thus safeguarding both the epigenomic and genomic integrity.