The histone methyltransferases Trithorax and Ash1 prevent transcriptional silencing by Polycomb group proteins.

摘要: Transcriptional on and off states of HOX genes other developmental control are maintained by antagonistic regulators encoded trithorax group (trxG) Polycomb (PcG) genes. The trxG proteins Ash1 hTRX the PcG repressor E(z) histone methyltransferases (HMTases) that methylate distinct lysine residues in N‐terminal tail H3. generally thought to function as activators genes, but how methylation Trx promotes gene transcription is not clear. Here, we show ash1 trx mutants expression lost within their normal domains, find that, contrary expectation, this restored also lack function. Moreover, such double severe misexpression and, hence, ectopic activation caused removal occurs absence Together, these results suggest HMTases ‘coactivators’ required for transcriptional specifically anti‐repressors. We propose continuously throughout development prevent inappropriate silencing cells which they must stay transcriptionally active.