Gene Silencing In Mitosis

摘要

It has been known for over 40 years that gene transcription shuts down during cell division. The common explanation has been that chromosome condensation limits RNA polymerase activity, but a study in budding yeast suggests this is not the case. Rather, the conserved phosphatase Cdcl4, a mitotic regulator required for nucleolar segregation and mitotic exit, causes gene silencing by preventing localization of RNA polymerase I to ribosomal DNA during anaphase. If ribosomal transcription is not shut down, the presence of transcripts prevents the loading of condensin and blocks chromosome condensation and segregation.