RESUMEN
Cohesin is important for 3D genome organization. Nevertheless, even the complete removal of cohesin has surprisingly little impact on steady-state gene transcription and enhancer activity. Here we show that cohesin is required for the core transcriptional response of primary macrophages to microbial signals, and for inducible enhancer activity that underpins inflammatory gene expression. Consistent with a role for inflammatory signals in promoting myeloid differentiation of hematopoietic stem and progenitor cells (HPSCs), cohesin mutations in HSPCs led to reduced inflammatory gene expression and increased resistance to differentiation-inducing inflammatory stimuli. These findings uncover an unexpected dependence of inducible gene expression on cohesin, link cohesin with myeloid differentiation, and may help explain the prevalence of cohesin mutations in human acute myeloid leukemia.
Asunto(s)
Proteínas de Ciclo Celular/metabolismo , Diferenciación Celular/genética , Autorrenovación de las Células/genética , Proteínas Cromosómicas no Histona/metabolismo , Células Madre Hematopoyéticas/fisiología , Leucemia Mieloide Aguda/genética , Macrófagos/fisiología , Proteínas Nucleares/genética , Fosfoproteínas/genética , Animales , Proteínas de Ciclo Celular/genética , Células Cultivadas , Proteínas Cromosómicas no Histona/genética , Proteínas de Unión al ADN , Regulación de la Expresión Génica , Secuenciación de Nucleótidos de Alto Rendimiento , Humanos , Inflamación/genética , Lipopolisacáridos/inmunología , Ratones , Ratones Noqueados , Mutación/genética , CohesinasRESUMEN
Upon recruitment to active enhancers and promoters, RNA polymerase II (Pol II) generates short non-coding transcripts of unclear function. The mechanisms that control the length and the amount of ncRNAs generated by cis-regulatory elements are largely unknown. Here, we show that the adaptor protein WDR82 and its associated complexes actively limit such non-coding transcription. WDR82 targets the SET1 H3K4 methyltransferases and the nuclear protein phosphatase 1 (PP1) complexes to the initiating Pol II. WDR82 and PP1 also interact with components of the transcriptional termination and RNA processing machineries. Depletion of WDR82, SET1, or the PP1 subunit required for its nuclear import caused distinct but overlapping transcription termination defects at highly expressed genes and active enhancers and promoters, thus enabling the increased synthesis of unusually long ncRNAs. These data indicate that transcription initiated from cis-regulatory elements is tightly coordinated with termination mechanisms that impose the synthesis of short RNAs.
Asunto(s)
Núcleo Celular/metabolismo , Elementos de Facilitación Genéticos/fisiología , Regiones Promotoras Genéticas/fisiología , ARN Polimerasa II/metabolismo , ARN no Traducido/biosíntesis , Terminación de la Transcripción Genética/fisiología , Transporte Activo de Núcleo Celular/fisiología , Animales , Núcleo Celular/genética , Proteínas Cromosómicas no Histona/genética , Proteínas Cromosómicas no Histona/metabolismo , N-Metiltransferasa de Histona-Lisina/genética , N-Metiltransferasa de Histona-Lisina/metabolismo , Ratones , Fosfoproteínas Fosfatasas/genética , Fosfoproteínas Fosfatasas/metabolismo , ARN Polimerasa II/genética , ARN no Traducido/genéticaRESUMEN
Prep1 is a homeodomain transcription factor that is essential in embryonic development and functions in the adult as a tumor suppressor. We show here that Prep1 is involved in maintaining genomic stability and preventing neoplastic transformation. Hypomorphic homozygous Prep1(i/i) fetal liver cells and mouse embryonic fibroblasts (MEFs) exhibit increased basal DNA damage and normal DNA damage response after γ-irradiation compared with WT. Cytogenetic analysis shows the presence of numerous chromosomal aberrations and aneuploidy in very early-passage Prep1(i/i) MEFs. In human fibroblasts, acute Prep1 down-regulation by siRNA induces DNA damage response, like in Prep1(i/i) MEFs, together with an increase in heterochromatin-associated modifications: rapid increase of histone methylation and decreased transcription of satellite DNA. Ectopic expression of Prep1 rescues DNA damage and heterochromatin methylation. Inhibition of Suv39 activity blocks the chromatin but not the DNA damage phenotype. Finally, Prep1 deficiency facilitates cell immortalization, escape from oncogene-induced senescence, and H-Ras(V12)-dependent transformation. Importantly, the latter can be partially rescued by restoration of Prep1 level. The results show that the tumor suppressor role of Prep1 is associated with the maintenance of genomic stability.