RESUMEN
The enhancer regions of the myogenic master regulator MyoD give rise to at least two enhancer RNAs. Core enhancer eRNA (CEeRNA) regulates transcription of the adjacent MyoD gene, whereas DRReRNA affects expression of Myogenin in trans. We found that DRReRNA is recruited at the Myogenin locus, where it colocalizes with Myogenin nascent transcripts. DRReRNA associates with the cohesin complex, and this association correlates with its transactivating properties. Despite being expressed in undifferentiated cells, cohesin is not loaded on Myogenin until the cells start expressing DRReRNA, which is then required for cohesin chromatin recruitment and maintenance. Functionally, depletion of either cohesin or DRReRNA reduces chromatin accessibility, prevents Myogenin activation, and hinders muscle cell differentiation. Thus, DRReRNA ensures spatially appropriate cohesin loading in trans to regulate gene expression.
Asunto(s)
Proteínas de Ciclo Celular/biosíntesis , Proteínas Cromosómicas no Histona/biosíntesis , Elementos de Facilitación Genéticos , Músculo Esquelético/metabolismo , Miogenina/biosíntesis , ARN no Traducido/metabolismo , Transcripción Genética , Animales , Proteínas de Ciclo Celular/genética , Diferenciación Celular , Cromatina/genética , Cromatina/metabolismo , Proteínas Cromosómicas no Histona/genética , Células HEK293 , Humanos , Ratones , Músculo Esquelético/citología , Proteína MioD/biosíntesis , Proteína MioD/genética , Miogenina/genética , ARN no Traducido/genética , CohesinasRESUMEN
The polycomb repressive complex 2 (PRC2) methylates lysine 27 of histone H3 (H3K27) through its catalytic subunit Ezh2. PRC2-mediated di- and tri-methylation (H3K27me2/H3K27me3) have been interchangeably associated with gene repression. However, it remains unclear whether these two degrees of H3K27 methylation have different functions. In this study, we have generated isogenic mouse embryonic stem cells (ESCs) with a modified H3K27me2/H3K27me3 ratio. Our findings document dynamic developmental control in the genomic distribution of H3K27me2 and H3K27me3 at regulatory regions in ESCs. They also reveal that modifying the ratio of H3K27me2 and H3K27me3 is sufficient for the acquisition and repression of defined cell lineage transcriptional programs and phenotypes and influences induction of the ESC ground state.