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.
Sex, Subject
View SamplesRNAseq gene expression following the repopulation of the langerhans cell network in immune deficient irradiated mice after ectopic injection of donor bone marrow cells Overall design: Allogeneic bone marrow transplantation with donor T cells leads to destruction of epidermal Langerhans cells (LC). Â This study aimed to investigate if and how the LC network was replaced under these conditions. We demonstrated that monocytes entered the epidermis and differentiated into monocyte-derived LC that were homologous to the cells they had replaced.
A wave of monocytes is recruited to replenish the long-term Langerhans cell network after immune injury.
Specimen part, Subject
View SamplesInnate lymphoid cells (ILCs) are considered to be the innate counterparts of adaptive T lymphocytes and play important roles in host defense, tissue repair, metabolic homeostasis, and inflammatory diseases. ILCs are generally thought of as tissue-resident cells, but whether ILCs strictly behave in a tissue-resident manner or can move between sites during infection is unclear. We show here that IL-25- or helminthic infection-induced inflammatory ILC2s are not tissue-resident but circulating cells, which arise from resting ILC2s residing in intestinal lamina propria and then migrate to mesenteric lymph nodes, spleen, lung, and liver. IL-25 induces rapid proliferation of the intestinal ILC2s and a change in their sensitivity to S1P-mediated chemotaxis, leading to lymphatic entry, blood circulation, and accumulation in periphery sites, including the lung where they contribute to anti-helminth defense and tissue repair. Our finding of cytokine-driven expansion and migration of innate lymphocytes, a behavioral parallel to the antigen-driven priming, expansion, and migration of adaptive lymphocytes to effector sites in distant tissues, provides a significant advance in our overall understanding of ILCs and indicates that ILCs complement adaptive immunity by providing both local and distant site effector protection during infection. Overall design: We examined the transcriptomes of BM ILC2 progenitors, lung nILC2s, IL-33-activated lung nILC2s, intestinal ILC2s, IL-25-induced lung iILC2s, and MLN iILC2s by RNA-Seq.
S1P-dependent interorgan trafficking of group 2 innate lymphoid cells supports host defense.
Specimen part, Cell line, Subject
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Specificity and heterogeneity of terahertz radiation effect on gene expression in mouse mesenchymal stem cells.
Specimen part
View SamplesWe report that terahertz (THz) irradiation of mouse mesenchymal stem cells with a pulsed broadband (centered at 10 THz) source, or a single-frequency, 2.52 THz, (SF) laser source, both with weak average power (<1mW/cm2), results in specific heterogenic changes in gene expression. The insignificant differential expression of heat shock and stress related genes as well as our temperature measurements imply a non-thermal response. The microarray survey and RT-PCR experiments demonstrate that at different irradiation conditions distinct groups of genes are activated. Stem cells irradiated for 12 hours with the broadband THz source exhibit an accelerated differentiation toward adipose phenotype, while the 2-hour (broadband or SF) irradiation affects genes transcriptionally active in pluripotent stem cells. Phenotypic and gene expression differences suggest that the THz effect depends on irradiation parameters such as duration and type of THz source, and on the level of stem cell differentiation. Computer simulations of the core promoters of two pluripotency markers reveal association between gene upregulation and propensity for DNA breathing. We propose that THz radiation has potential for non-contact control of cellular gene expression.
Specificity and heterogeneity of terahertz radiation effect on gene expression in mouse mesenchymal stem cells.
Specimen part
View SamplesWe report that terahertz (THz) irradiation of mouse mesenchymal stem cells with a pulsed broadband (centered at 10 THz) source, or a single-frequency, 2.52 THz, (SF) laser source, both with weak average power (<1mW/cm2), results in specific heterogenic changes in gene expression. The insignificant differential expression of heat shock and stress related genes as well as our temperature measurements imply a non-thermal response. The microarray survey and RT-PCR experiments demonstrate that at different irradiation conditions distinct groups of genes are activated. Stem cells irradiated for 12 hours with the broadband THz source exhibit an accelerated differentiation toward adipose phenotype, while the 2-hour (broadband or SF) irradiation affects genes transcriptionally active in pluripotent stem cells. Phenotypic and gene expression differences suggest that the THz effect depends on irradiation parameters such as duration and type of THz source, and on the level of stem cell differentiation. Computer simulations of the core promoters of two pluripotency markers reveal association between gene upregulation and propensity for DNA breathing. We propose that THz radiation has potential for non-contact control of cellular gene expression.
Specificity and heterogeneity of terahertz radiation effect on gene expression in mouse mesenchymal stem cells.
Specimen part
View SamplesWe report that terahertz (THz) irradiation of mouse mesenchymal stem cells with a pulsed broadband (centered at 10 THz) source, or a single-frequency, 2.52 THz, (SF) laser source, both with weak average power (<1mW/cm2), results in specific heterogenic changes in gene expression. The insignificant differential expression of heat shock and stress related genes as well as our temperature measurements imply a non-thermal response. The microarray survey and RT-PCR experiments demonstrate that at different irradiation conditions distinct groups of genes are activated. Stem cells irradiated for 12 hours with the broadband THz source exhibit an accelerated differentiation toward adipose phenotype, while the 2-hour (broadband or SF) irradiation affects genes transcriptionally active in pluripotent stem cells. Phenotypic and gene expression differences suggest that the THz effect depends on irradiation parameters such as duration and type of THz source, and on the level of stem cell differentiation. Computer simulations of the core promoters of two pluripotency markers reveal association between gene upregulation and propensity for DNA breathing. We propose that THz radiation has potential for non-contact control of cellular gene expression.
Specificity and heterogeneity of terahertz radiation effect on gene expression in mouse mesenchymal stem cells.
Specimen part
View SamplesWe report that extended exposure to broad-spectrum terahertz radiation results in specific changes in cellular functions that are closely related to DNA-directed gene transcription. Our gene chip survey of gene expression shows that whereas 89% of the protein coding genes in mouse stem cells do not respond to the applied teraherz radiation, certain genes are activated, while other are repressed. RT-PCR experiments with selected gene probes corresponding to transcripts in the three groups of genes detail the gene specific effect. The response was not only gene specific but also irradiation conditions dependent. Our findings suggest that the applied terahertz irradiation accelerates cell differentiation toward adipose phenotype by activating the transcription factor peroxisome proliferator-activated receptor gamma (PPARG). Finally, our molecular dynamics computer simulations indicate that the local breathing dynamics of the PPARG promoter DNA coincides with the gene specific response to the THz radiation. We propose that THz radiation is a potential tool for cellular reprogramming.
Mammalian stem cells reprogramming in response to terahertz radiation.
Specimen part, Treatment
View SamplesWe found that 5-Aza-dC/decitabine induces various prosurvival pathways (JAK-STAT-, NFkB-, MEK/ERK- and PI3K/AKTpathway) in cHL cell lines. Inhibition of these pathways with specific small molecular weight inhibitors potentiates the antitumor effect of 5-Aza-dC.
Activation of oncogenic pathways in classical Hodgkin lymphoma by decitabine: A rationale for combination with small molecular weight inhibitors.
Cell line
View SamplesAberrant DNA methylation is induced at specific promoter CpG islands (CGIs) in contrast with mutations. The specificity is influenced by genome architecture and epigenetic factors, but their relationship is still unknown. In this study, we isolated promoter CGIs susceptible and resistant to aberrant methylation induction during prostate and breast carcinogenesis. The effect of genome architecture was more evident for promoter CGIs susceptible in both of the two tissues than for promoter CGIs susceptible only in one tissue. Multivariate analysis of promoter CGIs with tissue-nonspecific susceptibility showed that genome architecture, namely a remote location from SINE (OR=5.98; 95% CI=2.33-15.34) and from LINE (OR=2.08; 95% CI=1.03-4.21), was associated with increased susceptibility, independent of epigenetic factors such as the presence of RNA polymerase II (OR=0.09; 95% CI=0.02-0.48) and H3K27me3 (OR=3.28; 95% CI=1.17-9.21). These results showed that methylation susceptibility of promoter CGIs is determined both by genome architecture and epigenetic factors, independently.
Effects of genome architecture and epigenetic factors on susceptibility of promoter CpG islands to aberrant DNA methylation induction.
Cell line
View Samples