Project description:The methylcytosine dioxygenase Tet3 is highly expressed as a specific isoform in oocytes and zygotes but essentially absent from later stages of mouse preimplantation development. Here, we show that Tet3 expression promotes transdifferentiation of embryonic stem cells to trophoblast-like stem cells. By genome-wide analyses we demonstrate that TET3 associates with and co-occupies chromatin with RNA Polymerase II. Tet3 expression induces a global increase of transcription and total RNA levels, and its presence further enhances chromatin accessibility in regions open for transcription. This novel function of TET3 is not specific to the oocyte isoform, independent of its catalytic activity, the CXXC domain, or its interaction with OGT, and is localised in its highly conserved exon 4. We propose a more general role for TET3 promoting open chromatin and enhancing global transcription during changes of cellular identity, separate from its catalytic function.
Project description:Tet-family dioxygenases catalyze conversion of 5-methylcytosine (5mC) to 5-hydroxymethylcytosine (5hmC) in DNA. Here, we show that Tet3 deficiency impairs neural differentiation of mouse ESCs, resulting in skewing towards cardiac mesoderm; conversely, ectopic expression of Tet3 enhances neural differentiation and limits cardiac mesoderm specification. To determine the effects of Tet3 gain and loss on global gene expression profiles during mESC differentiation, we performed whole transcriptome RNA-sequencing (RNA-seq) analysis of (i) WT and Tet3 KO mESCs differentiating into neuroectoderm under SFEB culture (days 6 and 10); and (ii) Control and Tet3-overexpressing mESCs in non-permissive neural differentiation conditions containing FBS (days 4 and 7). Genome-wide analyses showed that Tet3 mediates cell-fate decision by inhibiting Wnt signaling.
Project description:<p>In this study we profile the epigenomic enhancer landscapes of CLL B cells (CD19+/CD5+) harvested from peripheral blood of patients from our Center. Included are results of ChIPseq profiling using chromatin immunoprecipitation of the enhancer histone mark H3K27ac (acetylated lysine 27 on histone H3), and open chromatin profiles using ATAC-seq (assay for transposase accessible chromatin). These profiles are used to define the global enhancer and super enhancer landscape of CLL B cells, and to derive active transcription factor networks associated with this disease. Also included are H3K27ac ChIP-seq and ATAC-seq datasets for non-CLL B cells obtained from the peripheral blood of normal adult donors.</p>
Project description:Counter to the long-held belief that DNA methylation of terminally differentiated cells is permanent and essentially immutable, post-mitotic neurons exhibit extensive DNA demethylation. The causal role of active DNA demethylation in neurons, however, is not known. Tet family proteins oxidize 5-methylcytosine to initiate active DNA demethylation through the base-excision repair pathway. Here, we show that synaptic activity bi-directionally regulates neuronal Tet3 expression. Functionally, knockdown of Tet or inhibition of base-excision repair in hippocampal neurons elevates excitatory glutamatergic synaptic transmission, whereas overexpressing Tet3 or Tet1 catalytic domain decreases it. Furthermore, dysregulation of Tet3 signalling prevents homeostatic synaptic plasticity. Mechanistically, Tet3 dictates neuronal surface GluR1 levels. RNA-seq analyses further revealed a pivotal role of Tet3 in regulating gene expression in response to global synaptic activity changes. Thus, Tet3 serves as a synaptic activity sensor to epigenetically regulate basic properties and meta-plasticity of neurons via active DNA demethylation.
Project description:The intricate regulation of transcription underlies cellular differentiation and development. However, the general relevance of RNA-binding proteins (RBPs) in polymerase (Pol) II transcription is less understood. Here we revealed that WDR43, a novel chromatin-bound RBP, promotes transcription and is essential for self-renewal of embryonic stem cells (ESCs) and early embryonic development. WDR43 binds to promoter-associated non-coding and nascent RNAs, localizes at thousands of gene promoters and enhancers, and interacts with the Pol II transcription machinery. Recombinant WDR43 directly promotes transcription and the release of elongation factor P-TEFb in vitro. Depletion of WDR43 in ESCs leads to global defects in Pol II pause release and mRNA expression. These results demonstrate that WDR43 maintains high-level expression of pluripotency programs by modulating Pol II activity and transcription elongation. To extend these findings, we demonstrated widespread co-occupancy of open chromatin by multiple RBPs, suggesting an unforeseen role for RBPs in transcription control
Project description:In this study: (1) we distinguished Tet3 target genes that are regulated by its catalytic vs. noncatalytic functions in neuroectoderm (NE) cells by transcriptomic profiling of Tet3 wildtype (WT), Tet3 catalytic mutant (Mut), and Tet3 knockout (KO) NE cells by RNA-seq. (2) We mapped genome-wide DNA methylation of Tet3-WT, Tet3-Mut, and Tet3-KO NE cells by WGBS. (3) We determined Tet3 genome-wide occupancy in Tet3-WT NE cells by CUT&Tag. (4) We mapped 5hmC rich regions in Tet3-WT, Tet3-Mut, and Tet3-KO NE cells by hmeDIP. (5) We overexpressed (OE) the Tet3 target gene Dnmt1 (D) or an empty vector (EV) in Tet3-WT, Tet3-Mut, and Tet3-KO NE cells and assessed gene expression by RNA-seq. (6) We overexpressed (OE) Tet3 (T) or an empty vector (EV) in Tet3-WT, Tet3-Mut, and Tet3-KO NE cells and examined gene expression changes in these cells by RNA-seq.
Project description:Ten-eleven-translocation (TET) proteins catalyze DNA hydroxylation, playing an important role in demethylation of DNA in mammals. Remarkably, although hydroxymethylation levels are high in the mouse brain, the potential role of TET proteins in adult neurogenesis is unknown. We show here that a non-catalytic action of TET3 is essentially required for the maintenance of the neural stem cell (NSC) pool in the adult subventricular zone (SVZ) niche by preventing premature differentiation of NSCs into non-neurogenic astrocytes. This occurs through direct binding of TET3 to the paternal transcribed allele of the imprinted gene Small nuclear ribonucleoprotein-associated polypeptide N (Snrpn), contributing to transcriptional repression of the gene. The study also identifies BMP2 as an effector of the astrocytic terminal differentiation mediated by SNRPN. Our work describes a novel mechanism of control of an imprinted gene in the regulation of adult neurogenesis through an unconventional role of TET3.
Project description:TET enzymes oxidize 5-methylcytosine (5mC) into 5-hydroxymethylcytosine (5hmC), a process thought to be intermediary in an active DNA demethylation mechanism. Notably, 5hmC is highly abundant in the brain and in neuronal cells. Here we show that Tet3 is highly upregulated during neuronal differentiation and necessary to maintain silencing of pluripotency-associated genes in neural precursor cells (NPCs). Indeed, Tet3 knockdown (KD) in NPCs led to a significant increase in Oct4 and Nanog gene expression, with OCT4-positive cells appearing as cellular aggregates. Moreover, Tet3 KD led to a genome-scale loss of DNA methylation and hypermethylation of a small number of CpGs that are notably located at neurogenesis-related genes and at imprinting control regions (ICRs) of three imprinted genes (Peg10, Zrsr1 and Mcts2). Our results suggest that TET3 plays a pivotal role in maintaining neural stem cell identity and DNA methylation levels in neural precursor cells, and point to a non-catalytic role for TET3 in neural differentiation.
Project description:Small RNAs target their complementary chromatin regions for gene silencing through nascent long non-coding RNAs (lncRNAs). In programmed DNA elimination of the ciliated protozoan Tetrahymena, the interaction between Piwi-associated small RNA (scnRNAs) and the lncRNA transcripts from the somatic genome has been proposed to induce target-directed scnRNA degradation (TDSD) and scnRNAs not targeted for TDSD later target the germline-limited sequences for DNA elimination. In this study, we show that the SUMO E3 ligase Ema2 is required for the accumulation of lncRNAs from somatic genome, and thus for TDSD and completing DNA elimination to make viable sexual progeny. Ema2 interacts with the SUMO E2 conjugating enzyme Ubc9 and enhances SUMOylation of the transcription regulator Spt6. We further show that Ema2 promotes the association of Spt6 and RNA polymerase II to chromatin. These results suggest that Ema2-directed SUMOylation actively promotes the lncRNA transcription that is a prerequisite for communication between the genome and small RNAs.
Project description:The epithelium lining the epididymis in the male reproductive tract maintains a luminal environment that promotes sperm cell maturation. This process is dependent on the coordinated expression of many genes that encode proteins with a role in epithelial transport. We previously generated genome-wide maps of open chromatin in primary human fetal epididymis epithelial cells to identify potential regulatory elements controlling coordinated gene expression in the epididymis epithelium. Subsequent in silico analysis identified transcription factor binding sites (TFBS) that were over-represented in the HEE open chromatin, include the motif for paired box 2 (PAX2). PAX2 is a critical transcriptional regulator of urogenital tract development, which is well studied in the kidney but is unexplored in the epididymis. Due to the limited lifespan of primary HEE cells in culture we investigated the role of PAX2 in an immortalized HEE cell line (REP). First, REP cells were evaluated by DNase-seq and their open chromatin map overlapped that of primary HEE cells at ~ 65% of sites. Moreover, the PAX2-binding motif was again identified as an overrepresented TFBS within intergenic open chromatin, though on fewer chromosomes than in the primary HEE cells. To identify PAX2-target genes in REP cells, RNA-seq analysis was performed after siRNA-mediated depletion of PAX2 in comparison to a non-targeting siRNA. In response to PAX2-represssion, 3142 transcripts were differentially expressed (1334 up-regulated and 1808 down-regulated). Novel PAX2 targets included multiple genes encoding proteins with a predicted function in the epididymis epithelium. examination of open chromatin region in REP cells with 2 replicates