RESUMEN
Self-renewal and pluripotency of embryonic stem cells (ESCs) are established by multiple regulatory pathways operating at several levels. The roles of histone demethylases (HDMs) in these programs are incompletely defined. We conducted a functional RNAi screen for HDMs and identified five potential HDMs essential for mouse ESC identity. In-depth analyses demonstrate that the closely related HDMs Jmjd2b and Jmjd2c are necessary for self-renewal of ESCs and induced pluripotent stem cell generation. Genome-wide occupancy studies reveal that Jmjd2b unique, Jmjd2c unique, and Jmjd2b-Jmjd2c common target sites belong to functionally separable Core, Polycomb repressive complex (PRC), and Myc regulatory modules, respectively. Jmjd2b and Nanog act through an interconnected regulatory loop, whereas Jmjd2c assists PRC2 in transcriptional repression. Thus, two HDMs of the same subclass exhibit distinct and combinatorial functions in control of the ESC state. Such complexity of HDM function reveals an aspect of multilayered transcriptional control.
Asunto(s)
Células Madre Embrionarias/enzimología , Histona Demetilasas con Dominio de Jumonji/metabolismo , Células Madre Pluripotentes/enzimología , Transcripción Genética/fisiología , Animales , Línea Celular , Células Madre Embrionarias/citología , Estudio de Asociación del Genoma Completo , Proteínas de Homeodominio/genética , Proteínas de Homeodominio/metabolismo , Histona Demetilasas con Dominio de Jumonji/genética , Ratones , Proteína Homeótica Nanog , Células Madre Pluripotentes/citología , Complejo Represivo Polycomb 2/genética , Complejo Represivo Polycomb 2/metabolismo , Proteínas Proto-Oncogénicas c-myc/genética , Proteínas Proto-Oncogénicas c-myc/metabolismoRESUMEN
Here, we describe that lysine-specific demethylase 1 (Lsd1/KDM1a), which demethylates histone H3 on Lys4 or Lys9 (H3K4/K9), is an indispensible epigenetic governor of hematopoietic differentiation. Integrative genomic analysis, combining global occupancy of Lsd1, genome-wide analysis of its substrates H3K4 monomethylation and dimethylation, and gene expression profiling, reveals that Lsd1 represses hematopoietic stem and progenitor cell (HSPC) gene expression programs during hematopoietic differentiation. We found that Lsd1 acts at transcription start sites, as well as enhancer regions. Loss of Lsd1 was associated with increased H3K4me1 and H3K4me2 methylation on HSPC genes and gene derepression. Failure to fully silence HSPC genes compromised differentiation of hematopoietic stem cells as well as mature blood cell lineages. Collectively, our data indicate that Lsd1-mediated concurrent repression of enhancer and promoter activity of stem and progenitor cell genes is a pivotal epigenetic mechanism required for proper hematopoietic maturation. DOI:http://dx.doi.org/10.7554/eLife.00633.001.