Upon fertilisation, the highly differentiated gametes reprogram to a totipotent state to initiate a new developmental programme. Approximately half of the mammalian genome is composed of repetitive elements, including retrotransposons, some of which are transcriptionally activated after fertilisation. It is generally assumed that retrotransposons become activated as a side-effect of the large chromatin remodelling underlying the epigenetic reprogramming of the gametes. Here, we have used a targeted epigenomic approach to address whether specific families of retrotransposons play a direct role in chromatin organisation and developmental progression after fertilisation. Using this approach, we demonstrate that precocious silencing of LINE-1 reduces chromatin accessibility, while their prolonged activation prevents gradual chromatin compaction, natural to developmental progression. Preventing LINE-1 activation and interfering with their silencing results in a reduced developmental rate independently of the coding nature of the LINE-1 transcript, suggesting that LINE-1 functions primarily at the chromatin level. Our data suggest that activation of LINE-1 regulates global chromatin accessibility at the beginning of development and indicate that activation of retrotransposons is an integral part of the developmental programme. Overall design: RNAseq was done on pooled injected embryos(4-5) as indicated in methods.
LINE-1 activation after fertilization regulates global chromatin accessibility in the early mouse embryo.
Specimen part, Treatment, Subject
View SamplesPrecociously disseminated cancer cells may seed quiescent sites of future metastasis if they can protect themselves from immune surveillance. However, there is little knowledge about how such sites might be achieved. Here we present evidence that prostate cancer stem-like cells (CSC) can be found in histopathologically negative prostate draining lymph nodes (PDLN) in mice harboring oncogene-driven prostate intraepithelial neoplasia (mPIN). PDLN-derived CSC were phenotypically and functionally identical to CSC obtained from mPIN lesions, but distinct from CSCs obtained from frank prostate tumors. CSC derived from either PDLN or mPIN used the extracellular matrix protein Tenascin-C (TNC) to inhibit T cell receptor-dependent T cell activation, proliferation and cytokine production. Mechanistically, TNC interacted with 51 integrin on the cell surface of T cells, inhibiting reorganization of the actin-based cytoskeleton therein required for proper T cell activation. CSC from both PDLN and mPIN lesions also expressed CXCR4 and migrated in response to its ligand CXCL12, which was overexpressed in PDLN upon mPIN development. CXCR4 was critical for the development of PDLN-derived CSC, as in vivo administration of CXCR4 inhibitors prevented establishment in PDLN of an immunosuppressive microenvironment. Taken together, our work establishes a pivotal role for TNC in tuning the local immune response to establish equilibrium between disseminated nodal CSC and the immune system.
Tenascin-C Protects Cancer Stem-like Cells from Immune Surveillance by Arresting T-cell Activation.
Specimen part
View SamplesSkeletal muscle atrophy is a debilitating condition associated with weakness, fatigue, and reduced functional capacity. Nuclear factor-kappaB (NF-B) transcription factors play a critical role in atrophy. Knockout of genes encoding p50 or the NF-B co-transactivator, Bcl-3, abolish disuse atrophy and thus they are NF-B factors required for disuse atrophy. We do not know however, the genes targeted by NF-B that produce the atrophied phenotype. Here we identify the genes required to produce disuse atrophy using gene expression profiling in wild type compared to Nfkb1 (gene encodes p50) and Bcl-3 deficient mice. There were 185 and 240 genes upregulated in wild type mice due to unloading, that were not upregulated in Nfkb1-/- and Bcl-3-/- mice, respectively, and so these genes were considered direct or indirect targets of p50 and Bcl-3. All of the p50 gene targets were contained in the Bcl-3 gene target list. Most genes were involved with protein degradation, signaling, translation, transcription, and transport. To identify direct targets of p50 and Bcl-3 we performed chromatin immunoprecipitation of selected genes previously shown to have roles in atrophy. Trim63 (MuRF1), Fbxo32 (MAFbx), Ubc, Ctsl, Runx1, Tnfrsf12a (Tweak receptor), and Cxcl10 (IP-10) showed increased Bcl-3 binding to B sites in unloaded muscle and thus were direct targets of Bcl-3. p50 binding to the same sites on these genes either did not change or increased, supporting the idea of p50:Bcl-3 binding complexes. p65 binding to B sites showed decreased or no binding to these genes with unloading. Fbxo9, Psma6, Psmc4, Psmg4, Foxo3, Ankrd1 (CARP), and Eif4ebp1 did not show changes in p65, p50, or Bcl-3 binding to B sites, and so were considered indirect targets of p50 and Bcl-3. This work represents the first study to use a global approach to identify genes required to produce the atrophied phenotype with disuse.
Identification of genes that elicit disuse muscle atrophy via the transcription factors p50 and Bcl-3.
Sex, Specimen part
View Samples4-Hydroxynonenal (HNE), a cytotoxic and diffusible electrophile generated by the spontaneous decomposition of oxidized lipids, has a suspected role in neurodegenerative and inflammatory disease processes. In addition to promoting cell death, elevated levels of HNE lead to the engagement of cytoprotective signaling pathways, including the heat shock, antioxidant, DNA damage, and ER stress responses. Activation of the heat shock response, mediated by the transcription factor heat shock factor 1 (HSF1), is critical for maintaining cellular viability in the presence of HNE. Accordingly, silencing HSF1 expression using siRNA enhances the toxicity of HNE. Microarray analysis of samples from control and HSF1-silenced cells was performed to investigate which associated changes in gene could be responsible for the decrease in cellular viability.
HSF1-mediated BAG3 expression attenuates apoptosis in 4-hydroxynonenal-treated colon cancer cells via stabilization of anti-apoptotic Bcl-2 proteins.
No sample metadata fields
View SamplesTo identify atrophy genes directly targeted by Bcl-3 transactivator at a genome wide level, we performed whole transcript expression array and ChIP-seq for muscles from weight bearing or 5-day hind limb unloaded mice.
The ChIP-seq-defined networks of Bcl-3 gene binding support its required role in skeletal muscle atrophy.
Age, Specimen part
View SamplesThe sexually dimorphic expression of genes across 26 somatic rat tissues was using Affymetrix RAE-230 genechips. We considered probesets to be sexually dimorphically expressed (SDE) if they were measurably expressed above background in at least one sex, there was at least a two-fold difference in expression (dimorphism) between the sexes, and the differences were statistically significant after correcting for false discovery. 14.5% of expressed probesets were SDE in at least one tissue, with higher expression nearly twice as prevalent in males compared to females. Most were SDE in a single tissue. Surprisingly, nearly half of the probesets that were (SDE) in multiple tissues were oppositely sex biased in different tissues, and most SDE probesets were also expressed without sex bias in other tissues. Two genes were widely SDE: Xist (female-only) and Eif2s3y (male-only). The frequency of SDE probesets varied widely between tissues, and was highest in the duodenum (6.2%), whilst less than 0.05% in over half of the surveyed tissues. The occurrence of SDE probesets was not strongly correlated between tissues. Within individual tissues, however, relational networks of SDE genes were identified. In the liver, networks relating to differential metabolism between the sexes were seen. The estrogen receptor was implicated in differential gene expression in the duodenum. To conclude, sexually dimorphic gene expression is common, but highly tissue-dependent. Sexually dimorphic gene expression may provide insights into mechanisms underlying phenotypic sex differences.
The incidence of sexually dimorphic gene expression varies greatly between tissues in the rat.
Sex, Specimen part
View SamplesMany heavy metals, including nickel (Ni), cadmium (Cd), and chromium (Cr) are toxic industrial chemicals with an exposure risk in both occupational and environmental settings that may cause harmful outcomes. While these substances are known to produce adverse health effects leading to disease or health problems, the detailed mechanisms remain unclear. To elucidate the processes involved in the of toxicity of nickel, cadmium, and chromium at the molecular level and to perform a comparative analysis, H4-II-E-C3 rat liver-derived cell lines were treated with soluble salts of each metal using concentrations derived from viability assays, and gene expression patterns were determined with DNA microarrays.
Exposure to nickel, chromium, or cadmium causes distinct changes in the gene expression patterns of a rat liver derived cell line.
No sample metadata fields
View SamplesThe goal of this set of experiments was to identify transcripts that are differentially expressed upon reactivation of NMD in an nmd2::HIS3 strain by galactose-induced expression of the NMD2 gene.
Association of yeast Upf1p with direct substrates of the NMD pathway.
No sample metadata fields
View SamplesCachexia is an exacerbating event in many types of cancer that is strongly associated with a poor prognosis. We have identified cytokine, signaling and transcription factors that are required for cachexia in the mouse C26 colon carcinoma model of cancer. C2C12 myotubes treated with conditioned medium from C26 cancer cells induced atrophy and activated a STAT-dependent reporter gene but not reporter genes dependent on SMAD, FOXO, C/EBP, NF-B, or AP-1. Of the gp130 family members IL-11, IL-6, oncostatin M (OSM), and leukemia inhibitory factor (LIF), only OSM and LIF were sufficient to activate the STAT reporter in myotubes. A LIF blocking antibody abolished C26 CM-induced STAT reporter activation STAT3 phosphorylation and myotube atrophy, but blocking antibodies to IL-6 or OSM did not. JAK2 inhibitors also blocked the C26 CM-induced STAT reporter activation, STAT3 phosphorylation, and atrophy in myotubes. LIF at levels found in the C26 CM was sufficient for STAT reporter activation and atrophy in myotubes. In vivo, an increase in serum LIF preceded the increase in IL-6 in mice with C26 tumors. Overexpression of a dominant negative Stat3C-EGFP gene in myotubes and in mouse muscle blocked the atrophy caused by C26 CM or C26 tumors, respectively. Taken together these data support an important role of LIF- JAK2-STAT3 in C26 cachexia and point to a therapeutic approach for at least some types of cancer cachexia.
A Key Role for Leukemia Inhibitory Factor in C26 Cancer Cachexia.
Specimen part, Time
View SamplesEffect of either FLO8 or MSS11 deletion and -overexpression on yeast transcript profiles compared to wild type in laboratory yeast strains 1278b and S288c - also the effect of FLO11 (MUC1) overexpression in the 1278b genetic background
Many Saccharomyces cerevisiae Cell Wall Protein Encoding Genes Are Coregulated by Mss11, but Cellular Adhesion Phenotypes Appear Only Flo Protein Dependent.
No sample metadata fields
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