Argonaute (Ago) proteins mediate post-transcriptional gene repression by binding guide microRNAs (miRNAs) to regulate targeted RNAs. To confidently assess Agobound small RNAs, we adapted a mouse embryonic stem cell system to express a single inducible epitope-tagged Ago protein. Here, we report the small RNA profile of Agodeficient cells and determine Ago-dependent stability is a common feature of mammalian miRNAs. Considering both in vivo Ago-dependence for stability and Ago2 binding as defined by immunopurification, we have identified a novel class of non-canonical miRNAs derived from protein-coding gene promoters, which we name transcriptional start site miRNAs (TSS-miRNAs). A subset of promoter-proximal RNA polymerase II complexes produce hairpin RNAs that are processed in a DGCR8/Drosha-independent, but Dicer-dependent manner. TSS-miRNA activity is detectable endogenously, upon transfection of a mimic or by mRNA overexpression. Finally, we present evidence of differential expression and conservation in humans, suggesting important roles in gene regulation. Overall design: Examination of Ago immunoprecipitations and mESC without Ago proteins
Argonaute-bound small RNAs from promoter-proximal RNA polymerase II.
Specimen part, Treatment, Subject
View SamplesTarget competition (ceRNA crosstalk) within miRNA-regulated gene networks has been proposed to influence biological systems. To assess target competition, we characterize and quantitate miRNA networks in two cell types. Argonaute iCLIP reveals that hierarchical binding of high to low affinity miRNA targets is a key characteristic of in vivo activity. Quantification of cellular miRNA and mRNA/ncRNA target pool levels indicates that miRNA-Target pool ratios and an affinity partitioned target pool accurately predict in vivo Ago binding profiles and miRNA susceptibility to target competition. Using single-cell reporters, we directly test predictions and estimate ~3,000 additional high affinity target sites can affect active miRNA families with low endogenous miRNA-Target ratios, such as miR-92/25. In contrast, the highly expressed miR-294 and let-7 families are not susceptible to increases of nearly 10,000 sites. These results show differential susceptibility based on endogenous miRNA-Target pool ratios and provide a physiological context for ceRNA competition in vivo. Overall design: mRNA seq from TT-FHAgo2 mouse embryonic stem cells or Meschencymal stem cells grown with 2.5 µg/mL Dox to express Ago2 or removed from doxycycline for 96h.
Endogenous miRNA and target concentrations determine susceptibility to potential ceRNA competition.
No sample metadata fields
View SamplesArgonaute (Ago) proteins, which act in post-transcriptional gene regulation directed by small RNAs, are vital for normal stem cell biology. Here we report the genomic characterization of stable Ago-deficient mouse embryonic stem cells (mESC) and determine the direct, primary and system level response to loss of Ago-mediated regulation. We find mESCs lacking all four Ago proteins are viable, do not repress microRNA (miRNA)-targeted cellular RNAs, and show distinctive gene network signatures. Profiling of RNA expression and epigenetic activity in an Ago mutant genetic series indicates that early responses to Ago loss are driven by transcriptional regulatory networks, in particular the Tgf-ß/Smad transcriptional network. This finding is confirmed using a time course analysis of Ago depletion and Ago rescue experiments. Detailed analysis places Tgf-ß/Smad activation upstream of cell cycle regulator activation, such as Cdkn1a, and repression of the c-Myc transcriptional network. The Tgf-ß/Smad pathway is directly controlled by multiple low-affinity miRNA interactions with Tgf-ß/Activin receptor mRNAs and receptor-mediated activation is required for Tgf-ß/Smad target induction with Ago loss. Our characterization reveals the interplay of post-transcriptional regulatory pathways with transcriptional networks in maintaining cell state and likely coordinating cell state transitions. Overall design: mRNA seq from stable genetic Dicer and Dgcr8 mutant mouse embryonic stem cells.
Temporal Control of the TGF-β Signaling Network by Mouse ESC MicroRNA Targets of Different Affinities.
Specimen part, Cell line, Subject
View SamplesWe examined the kinetics of production of mRNAs and small RNAs derived from transposable elements during mouse spermatogenesis, in whole gonads of wildtype and DNA methylation-deficient males (Dnmt3L and Miwi2 mutants). We found that in absence of DNA methylation, transposon reactivation is not constitutive but rather occurs in a class- and development-specific manner : both the intensity of reactivation and the number of reactivated transposon classes increased as germ cells progress in meiosis. Moreover, we observed that transposon silencing before meiosis is not due to increased cleavage by the piRNA machinery. In contrast, the burst of transposon transcripts occurring at meiosis in the absence of DNA methylation serve as substrates for increased piRNA production Overall design: Six whole testis samples were analyzed, corresponding to three time points (16.5dpc, 10dpp and 20dpp) each for Dnamt3L-/- animals and control littermates. For 16.5dpc, testes from 7/8 mice were pooled per genotype. For the other stages, three mice were pooled per genotype.
DNA methylation restrains transposons from adopting a chromatin signature permissive for meiotic recombination.
No sample metadata fields
View SamplesThe p53-regulated long non-coding RNA, lincRNA-p21, has been proposed to promote apoptosis and to repress in trans the expression of genes in the p53 transcriptional network. Here, we report the generation of a conditional knockout mouse model developed to further examine lincRNA-p21 function. Using this genetic approach, we find that the primary function of lincRNA-p21 is to activate in cis the expression of its neighboring gene, the cyclin-dependent kinase inhibitor p21. Mechanistically, we show that lincRNA-p21 acts in concert with hnRNP-K as a co-activator for p53-dependent transcription of p21. Additional phenotypes of lincRNA-p21 deficiency, including deregulated expression and altered chromatin state of a set of Polycomb target genes, defective G1/S checkpoint, increased proliferation rates, and enhanced reprogramming efficiency could be attributed to diminished p21 levels. This study reveals a novel paradigm, whereby the long non-coding RNA lincRNA-p21 affects global gene expression and influences events in the p53 tumor suppressor pathway by acting in cis as a locus-restricted transcriptional co-activator for p53-mediated expression of p21. Overall design: mRNAseq in 2 cell types (WT and lincRNA-p21 KO) in the presence and absence of Doxorubicin performed in biological triplicate.
LincRNA-p21 activates p21 in cis to promote Polycomb target gene expression and to enforce the G1/S checkpoint.
No sample metadata fields
View SamplesThe Microrchidia (Morc) family of GHKL ATPases are present in a wide variety of prokaryotic and eukaryotic organisms but are of largely unknown function. Genetic screens in Arabidopsis thaliana have identified Morc genes as important repressors of transposons and other DNA methylated and silent genes. MORC1 deficient mice were previously found to display male-specific germ cell loss and infertility. Here we show that MORC1 is responsible for transposon repression in the male germline in a pattern that is similar to that observed for germ cells deficient for the DNA methyltransferase homolog DNMT3L. Morc1 mutants show highly localized defects in the establishment of DNA methylation at specific classes of transposons, and this is associated with failed transposon silencing at these sites. Our results identify MORC1 as an important new regulator of the epigenetic landscape of male germ cells during the period of global de novo methylation. Overall design: This data includes: 47 RNA-seq, 4 smRNA-seq, 6 BS-seq, and 2 ChIP-seq datasets
MORC1 represses transposable elements in the mouse male germline.
No sample metadata fields
View SamplesThere is considerable evidence that chromosome structure plays important roles in gene control, but we have limited understanding of the proteins that contribute to structural interactions between gene promoters and their enhancer elements. Large DNA loops that encompass genes and their regulatory elements depend on CTCF-CTCF interactions, but most enhancer-promoter interactions do not depend on this structural protein. Here we show that the transcription factor Yin Yang 1 (YY1) contributes to enhancer-promoter structural interactions in a manner analogous to DNA interactions mediated by CTCF. YY1 binds to active enhancers and promoter-proximal elements in all cells examined. YY1 forms dimers that can facilitate DNA interactions. Deletion of YY1 binding sites or depletion of YY1 can disrupt enhancer-promoter looping and normal gene expression. We propose that YY1-mediated enhancer-promoter interactions are a general feature of mammalian gene control. Overall design: Single-end 40 bp Poly-A RNA-seq in mouse embryonic stem cells before and after YY1 depletion
YY1 Is a Structural Regulator of Enhancer-Promoter Loops.
Specimen part, Treatment, Subject, Time
View SamplesThere is considerable evidence that chromosome structure plays important roles in gene control, but we have limited understanding of the proteins that contribute to structural interactions between gene promoters and their enhancer elements. Large DNA loops that encompass genes and their regulatory elements depend on CTCF-CTCF interactions, but most enhancer-promoter interactions do not depend on this structural protein. Here we show that the transcription factor Yin Yang 1 (YY1) contributes to enhancer-promoter structural interactions in a manner analogous to DNA interactions mediated by CTCF. YY1 binds to active enhancers and promoter-proximal elements in all cells examined. YY1 forms dimers that can facilitate DNA interactions. Deletion of YY1 binding sites or depletion of YY1 can disrupt enhancer-promoter looping and normal gene expression. We propose that YY1-mediated enhancer-promoter interactions are a general feature of mammalian gene control. Overall design: Single-cell RNA-seq in mouse embryonic stem cells with and without YY1 protein
YY1 Is a Structural Regulator of Enhancer-Promoter Loops.
Specimen part, Subject
View SamplesGene expression is controlled by transcription factors (TFs) that consist of DNA-binding domains (DBDs) and activation domains (ADs). The DBDs have been well- characterized, but little is known about the mechanisms by which ADs effect gene activation. Here we report that diverse ADs form phase-separated condensates with the Mediator coactivator. For the OCT4 and GCN4 TFs, we show that the ability to form phase-separated droplets with Mediator in vitro and the ability to activate genes in vivo are dependent on the same amino acid residues. For the estrogen receptor (ER), a ligand-dependent activator, we show that estrogen enhances phase separation with Mediator, again linking phase separation with gene activation. These results suggest that diverse TFs can interact with Mediator through the phase-separating capacity of their ADs and that formation of condensates with Mediator is involved in gene activation. Overall design: RNA-seq in mouse embryonic stem cells after OCT4 degradation or LIF withdrawal
Transcription Factors Activate Genes through the Phase-Separation Capacity of Their Activation Domains.
Treatment, Subject
View SamplesSuper-enhancers (SEs) are clusters of enhancers that cooperatively assemble a high density of transcriptional apparatus to drive robust expression of genes with prominent roles in cell identity. We recently proposed that a phase-separated multi-molecular assembly underlies the formation and function of SEs. Here, we demonstrate that the SE-enriched factors BRD4 and MED1 form nuclear puncta that occur at SEs and exhibit properties of liquid-like condensates. Disruption of BRD4 and MED1 puncta by 1,6-hexanediol is accompanied by a loss of BRD4 and MED1 at SEs and a loss of RNAPII from SE-driven genes. We find that the intrinsically disordered regions (IDRs) of BRD4 and MED1 are sufficient to form phase-separated droplets in vitro and the MED1 IDR promotes phase separation in living cells. The MED1 IDR droplets are capable of compartmentalizing BRD4 and other transcriptional machinery in nuclear extracts. These results support the idea that SEs form phase-separated condensates that compartmentalize the transcription apparatus at key genes, provide insights into the role of cofactor IDRs in this process, and offer new insights into mechanisms involved in control of key cell identity genes. Overall design: polyA RNA-Seq in mouse embryonic stem cells
Coactivator condensation at super-enhancers links phase separation and gene control.
Specimen part, Subject
View Samples