Multiple signaling pathways, structural proteins and transcription factors are involved in regulation of endothelial barrier function. The Forkhead protein FOXF1 is a key transcriptional regulator of lung embryonic development, and we use a conditional knockout approach to examine the role of FOXF1 in adult lung homeostasis and lung injury and repair. Tamoxifen-regulated deletion of both Foxf1 alleles in endothelial cells of adult mice (Pdgfb-iCreER/Foxf1 caused lung inflammation and edema, leading to respiratory insuffency and uniform mortality. Deletion of a single foxf1 allele was sufficient to increase susceptibility of heterozygous mice to acute lung injury. FOXF1 abundance was decreased in pulmonary endothelial cells of human patients with acute lung injury. Gene expression analysis of pulmonary endothelial cells of FOXF1 deletion indicated reduced expression for genes critical for maintance and regulation of adherens junctions. FOXF1 knockdown in vitro and in vivo disrupted adherens junctions, increased lung endothelial permeability, and the abundance of mRNA and protein for sphingosine 1 phosphate receptor 1 (S1PR1), a key regulator of endothelial barrier function. Chromatin immunoprecipitation and luciferase reporter assay demonstrated that FOXF1 directly bound to and induced the tanscriptional activity of the S1pr1 promoter. Pharmacological administratiion of S1P to injured pdgfb-iCreER/Foxf1 mice restored endothelial barrier function, decreased lung edema and improved survival. Thus, FOXF1 promotes normal lung homeostasis and lung repair, at least in part, by enhancing endothelial barrier function through transcriptional activation of the S1P/S1PR1/ signaling pathway. Overall design: RNA was isolated and pooled from the lungs of multiple mice with either the Foxf1 floxed alleles alone or Pdgfb-iCreER Foxf1 floxed mice.
FOXF1 maintains endothelial barrier function and prevents edema after lung injury.
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Germline nuclear RNAi in C. elegans is a transgenerational gene-silencing pathway that leads to the H3K9 trimethylation (H3K9me3) response and transcriptional repression of target genes. The H3K9me3 response induced either by exogenous dsRNA or endogenous siRNA (endo-siRNA) is highly specific to the target loci and transgenerationally heritable. Despite these features, the role of H3K9me3 in transcriptional repression and heritable gene silencing at native target genes has not been tested. To resolve this gap, we first determined that the combined activities of three H3K9 histone methyltransferases (HMTs), MET-2, SET-25, and SET-32, are responsible for virtually all of the detectable level of germline nuclear RNAi-dependent H3K9me3 at native genes, triggered either by exogenous dsRNA or endo-siRNAs. By performing RNA Polymerase II ChIP-seq and pre-mRNA-seq analyses, we found that the loss of the H3K9me3 response at germline nuclear RNAi targets in the met-2;set-25;set-32 mutant does not lead to any defect in transcriptional repression or heritable RNAi. Therefore, H3K9me3 is not required for exogenous dsRNA-induced heritable RNAi or the maintenance of endo siRNA-mediated transcriptional silencing in C. elegans germline. This study provides a unique paradigm in which transcriptional silencing and heterochromatin, triggered by the same upstream pathway, can be decoupled. Overall design: In this study we tested if RNAi-mediated H3K9me3 is required for the heritable RNAi and transcriptional silencing at native endogenous and exogenous RNAi targets. Using genetic approach we generated nearly completely deficient H3K9me3 worm strain (met-2;set-25;set-32). Using Pol II ChIP-seq, pre-mRNA-seq and mRNA-seq we validated transcriptional changes at the endogenous targets in the H3K9me3 deficient condition (met-2;set-25;set-32). We performed oma-1 dsRNA feeding and heritable RNAi experiment and using H3K9me3 ChIP-seq measured level of RNAi-triggered H3K9me3 contribution by set-32 or met-2;set-25 or met-2;set-25;set-32 HMTs at the oma-1 gene. Using oma-1 mRNA and pre-mRNA qRT-PCR we tested heritable RNAi effect at oma-1 genomic locus in these HMT mutants.
Decoupling the downstream effects of germline nuclear RNAi reveals that H3K9me3 is dispensable for heritable RNAi and the maintenance of endogenous siRNA-mediated transcriptional silencing in <i>Caenorhabditis elegans</i>.
Environmental stress-induced transgenerational epigenetic effects have been observed in various model organisms and human. The capacity and mechanism of such phenomena, particularly in animals, are poorly understood. In C. elegans, siRNA mediates transgenerational gene silencing through the germline nuclear RNAi pathway. At the organismal level, this pathway plays a transgenerational role in maintaining the germline immortality when C. elegans is under a mild heat stress. However, the underlying molecular mechanism is unknown. In this study, we performed a 12-generation temperature-shift experiment (15°C->23°C->15°C) using the wild type (N2) and a mutant strain that lacks the germline-specific nuclear AGO protein HRDE-1/WAGO-9. We found that the temperature-sensitive mortal germline (Mrt) phenotype of the hrde-1 mutant is reversible, indicating a transgenerational cumulative but also reversible nature of the underlying molecular cause. By taking the whole-genome RNA and chromatin profiling approaches, we revealed an epigenetic role of HRDE-1 in repressing heat stress-induced transcriptional activation of over 280 genes, predominantly in or near LTR retrotransposons. Strikingly, for some of these elements, the heat stress-induced transcription becomes progressively activated in the hrde-1 mutant over several generations under heat stress. Furthermore, the effect of heat stress-induced transcription activation is heritable for at least two generations after the heat stress. Interestingly, the siRNA expression of these genes tend to be heat-inducible in the wild type animals, but not in the hrde-1 mutant, suggesting a role of siRNAs in repressing heat-inducible elements. Our study revealed a novel phenomenon of transgenerational feed-forward transcriptional activation, which is normally repressed in the wild type C. elegans by the germline nuclear RNAi pathway. It also provides a new paradigm to study epigenetic circuitry that connects the environment and gene regulation in the germline. Overall design: In this study, we performed a 12-generation temperature-shift experiment (15°C->23°C->15°C) using the wild type and hrde-1 mutant. mRNA-seq, Pol II ChIP-seq, H3K9me3 ChIP-seq, and small RNA-seq analyses were performed for all or some of the generations. The effects of temperature change in whole-genome mRNA expression, siRNA expression, gene transcription, and H3K9me3 were investigated at the multigenerational time scale in both the WT and hrde-1 mutant animals.
A transgenerational role of the germline nuclear RNAi pathway in repressing heat stress-induced transcriptional activation in C. elegans.
Epigenetic inheritance contributes fundamentally to transgenerational physiology and fitness. Mechanistic understanding of RNA-mediated chromatin modification and transgenerational epigenetic inheritance, which in C. elegans can be triggered by exogenous double-stranded RNA (exo-dsRNA) or facilitated by endogenous small interfering RNAs (endo-siRNAs), has mainly been limited to the post-initiation phases of silencing. Indeed, the dynamic process by which nuclear RNAi engages a transcriptionally active target, before the repressive state is stably established, remains largely a mystery. Here we found that the onset of exo-dsRNA-induced nuclear RNAi is a transgenerational process, and that establishment requires SET-32, one of the three putative histone methyltransferases (HMTs) that are required for H3K9me3 deposition at the nuclear RNAi targets. We also performed multigenerational whole-genome analyses to examine the establishment of silencing at endogenous targets of germline nuclear RNAi. The nuclear Argonaute (AGO) protein HRDE-1 is essential for the maintenance of nuclear RNAi. Repairing a loss-of-function mutation in hrde-1 by CRISPR restored the silencing of endogenous targets in animals carrying wild type set-32. However, for numerous endogenous targets, repairing the hrde-1 mutation in a set-32;hrde-1 double mutant failed to restore their silencing states in up to 20 generations after the hrde-1 repair, using a similar genome editing approach. We found that despite a prominent role in the establishment of silencing, however, set-32 is completely dispensable for the maintenance of silencing once HRDE-1-dependent gene repression is established. Our study indicates that: 1) initiation and maintenance of siRNA-guided transcriptional repression are two distinct processes with different genetic requirements; and 2) the rate-limiting step of the establishment phase is a transgenerational, chromatin-based process. In addition, our study reveals a novel paradigm in which a heterochromatin factor primarily functions to promote the initiation of transgenerational silencing, expanding mechanistic understanding of the well-recognized role of heterochromatin in epigenetic maintenance. Overall design: 23 samples were analyzed using RNA-seq
C. elegans Heterochromatin Factor SET-32 Plays an Essential Role in Transgenerational Establishment of Nuclear RNAi-Mediated Epigenetic Silencing.
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Hepatic fibrosis is the common end stage to a variety of chronic liver injuries and is characterized by an excessive deposition of extracellular matrix (ECM), which disrupts the liver architecture and impairs liver function. The fibrous lesions are produced by myofibroblasts, which differentiate from hepatic stellate cells (HSC). The myofibroblasts transcriptional networks remain poorly characterized. Previous studies have shown that the Forkhead box F1 (FOXF1) transcription factor is expressed in HSCs and stimulates their activation during acute liver injury; however, the role of FOXF1 in the progression of hepatic fibrosis is unknown. In the present study, we generated aSMACreER;Foxf1fl/fl mice to conditionally inactivate Foxf1 in myofibroblasts during carbon tetrachloride-mediated liver fibrosis. Foxf1 deletion increased collagen depositions and disrupted liver architecture. Timp2 expression was significantly increased in Foxf1-deficient mice while MMP9 activity was reduced. RNA sequencing of purified liver myofibroblasts demonstrated that FOXF1 inhibits expression of pro-fibrotic genes, Col1a2, Col5a2, and Mmp2 in fibrotic livers and binds to active repressors located in promotors and introns of these genes. Overexpression of FOXF1 inhibits Col1a2, Col5a2, and MMP2 in primary murine HSCs in vitro. Altogether, FOXF1 prevents aberrant ECM depositions during hepatic fibrosis by repressing pro-fibrotic gene transcription in myofibroblasts and HSCs. Overall design: RNAseq on isolated hepatic stromal cells from Foxf1 fl/fl and aSMACreER;Foxf1 fl/fl mice after 5 weeks of carbon tetrachloride-induced liver injury.
The Forkhead box F1 transcription factor inhibits collagen deposition and accumulation of myofibroblasts during liver fibrosis.
Specimen part, Cell line, SubjectView Samples
Transcription factor FoxM1 is expressed in proliferating cells, and its expression is critical for cell proliferation in embryos and tumors. FoxM1 regulates a multi-gene transcriptional network for cell cycle regulation.
Forkhead box M1 transcriptional factor is required for smooth muscle cells during embryonic development of blood vessels and esophagus.
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MHC class I-related molecule MR1 presents riboflavin-derived microbial metabolites and folate-derivatives to mucosal-associated invariant T cells, but it is unknown whether MR1 can bind alternative antigens that stimulate other T cell lineages. Here we report that human T cells displaying diverse TCR-a and ß chains recognize MR1-expressing cells in the absence of microbial ligands and respond to recombinant MR1 molecules loaded with antigens extracted from stimulatory targets. Transcriptome analysis revealed functional heterogeneity of MR1-reactive T cells (MR1T cells), which displayed differential expression of various transcription factors regulating T cell polarization, proliferation and apoptosis. Accordingly, MR1T cells displayed multiple profiles of chemokine receptor expression and secreted variable combinations of cytokines and growth factors, suggesting a diversity of immunological roles across numerous tissues. Functionally, MR1T cells were capable of inducing dendritic cell maturation and stimulating anti-microbial responses in intestinal epithelial cells. These data demonstrate that MR1 presents endogenous antigens to a novel population of functionally diverse human T cells. Overall design: mRNA profiles of two representative MR1T cell clones in resting (not exposed to antigen) and activated (stimulated with A375-MR1 antigen target cells and activated) states
Functionally diverse human T cells recognize non-microbial antigens presented by MR1.
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Goal of this study was to assess the levels of protection and investigate cellular, humoral, and mucosal immune correlates on the functional and gene transcriptional levels in elite-controller macaques following high dose SIV challenge.
Rapid SIV Env-specific mucosal and serum antibody induction augments cellular immunity in protecting immunized, elite-controller macaques against high dose heterologous SIV challenge.
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HESC-H9 and iPSC lines 3.5, 3.6 and 3.12 were analyzed using Affymetrix microarray before and after Definitive Endoderm (DE) formation. DE was induced using the ActivinA differentiation protocol described by D'Amour et al., 2006 (PMID: 16258519) Clustering analysis of transcripts that were differentially regulated during DE formation indicated that iPSC lines 3.5 and 3.12 differentiate in manner that is highly similar to HESC-H9 cells iPSC line 3.6 had a more divergent transcriptional profile.
Directed differentiation of human pluripotent stem cells into intestinal tissue in vitro.
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We report single cell expression in mouse young and old aorta endothelial cells. These data provide insight in the gene expression related to regeneration of mouse aorta endothelial layer. Overall design: Single cell RNA sequencing was done on a young mouse (8 weeks) and an old mouse (18 months), 10X Genomics Single Cell 3' v2 was used.
Endothelial Regeneration of Large Vessels Is a Biphasic Process Driven by Local Cells with Distinct Proliferative Capacities.
Age, Specimen part, Cell line, SubjectView Samples