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.
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•Jmjd2b and Jmjd2c are required for self-renewal of mESCs•Jmjd2b and Jmjd2c are associated with different regulatory modules in mESCs•Jmjd2b and Nanog act through an interconnected regulatory loop•Jmjd2c assists PRC2 in full transcriptional repression
Linker histone H1 proteins bind to nucleosomes and facilitate chromatin compaction
, although their biological functions are poorly understood. Mutations in the genes that encode H1 isoforms B-E ...(H1B, H1C, H1D and H1E; also known as H1-5, H1-2, H1-3 and H1-4, respectively) are highly recurrent in B cell lymphomas, but the pathogenic relevance of these mutations to cancer and the mechanisms that are involved are unknown. Here we show that lymphoma-associated H1 alleles are genetic driver mutations in lymphomas. Disruption of H1 function results in a profound architectural remodelling of the genome, which is characterized by large-scale yet focal shifts of chromatin from a compacted to a relaxed state. This decompaction drives distinct changes in epigenetic states, primarily owing to a gain of histone H3 dimethylation at lysine 36 (H3K36me2) and/or loss of repressive H3 trimethylation at lysine 27 (H3K27me3). These changes unlock the expression of stem cell genes that are normally silenced during early development. In mice, loss of H1c and H1e (also known as H1f2 and H1f4, respectively) conferred germinal centre B cells with enhanced fitness and self-renewal properties, ultimately leading to aggressive lymphomas with an increased repopulating potential. Collectively, our data indicate that H1 proteins are normally required to sequester early developmental genes into architecturally inaccessible genomic compartments. We also establish H1 as a bona fide tumour suppressor and show that mutations in H1 drive malignant transformation primarily through three-dimensional genome reorganization, which leads to epigenetic reprogramming and derepression of developmentally silenced genes.
A series of five related publications describe an alternative pluripotent state that is dependent on continuous high levels of exogenous reprogramming factor expression. A comprehensive effort to ...molecularly compare the acquisition of this state to induced pluripotency aims at providing new insights into the mechanisms underlying cellular reprogramming.
A series of five related publications describe an alternative pluripotent state that is dependent on continuous high levels of exogenous reprogramming factor expression. A comprehensive effort to molecularly compare the acquisition of this state to induced pluripotency aims at providing new insights into the mechanisms underlying cellular reprogramming.
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 mESC identity. In depth analyses demonstrate that the closely related HDMs, Jmjd2b and Jmjd2c, are necessary for self-renewal of ESCs and iPSC generation. Genome-wide occupancy studies reveal 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 a novel aspect of multilayered transcriptional control.
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