SETDB1,also named as ESET,KIAA0067 and KMT1E,belongs to the histone-lysine methyltransferase family. It is a SET domain protein with histone H3-K9-specific methyltransferase activity. H3 'Lys-9' trimethylation is coordinated with DNA methylation and represents a specific tag for epigenetic transcriptional repression by recruiting HP1 (CBX1,CBX3 and/or CBX5) proteins to methylated histones. SETDB1 mainly functions in euchromatin regions,thereby playing a central role in the silencing of euchromatic genes. It probably forms a complex with MBD1 and ATF7IP that represses transcription and couples DNA methylation and histone 'Lys-9' trimethylation. Its activity is dependent on MBD1 and is heritably maintained through DNA replication by being recruited by CAF-1. SETDB1 regulates histone methylation,gene silencing,and transcriptional repression. It has been identified as a target for treatment in Huntington Disease,given that gene silencing and transcription dysfunction likely play a role in the disease pathogenesis.
