Repressive Transcription

Abstract

How are active and repressed portions of the genome established and maintained during development? In vertebrates, about 2 m of DNA is packaged into chromatin in a manner that allows for active transcription of some loci and repression of others. Most chromatin regulators do not recognize specific DNA sequences, so how are they recruited to specific sites throughout the genome? For actively transcribed genes, transcription factors or the transcription initiation apparatus recruit regulators associated with active chromatin (1). For genes that are repressed, recent studies suggest a counterintuitive model: Transcription initiates the formation of repressive chromatin (2–9).