Double-stranded RNA-binding proteins are key elements in the intracellular localization of mRNA and its local translation. Staufen is a double-stranded RNA binding protein involved in the localised translation of specific mRNAs during Drosophila early development and neuronal cell fate. The human homologue Staufen1 forms RNA-containing complexes that include proteins involved in translation and motor proteins to allow their movement within the cell, but the mechanism underlying translation repression in these complexes is poorly understood. Here we show that human Staufen1-containing complexes contain essential elements of the gene silencing apparatus, like Ago1-3 proteins, and we describe a set of miRNAs specifically associated to complexes containing human Staufen1. Among these, miR124 stands out as particularly relevant because it appears enriched in human Staufen1 complexes and is over-expressed upon differentiation of human neuroblastoma cells in vitro. In agreement with these findings, we show that expression of human Staufen1 is essential for proper dendritic arborisation during neuroblastoma cell differentiation, yet it is not necessary for maintenance of the differentiated state, and suggest potential human Staufen1 mRNA targets involved in this process.
Human Staufen1 associates to miRNAs involved in neuronal cell differentiation and is required for correct dendritic formation.
Cell line
View SamplesGene expression profiles of peripheral blood samples from C57BL/6 mice exposed with ionizing radiation.
Biological pathway selection through Bayesian integrative modeling.
Sex, Specimen part, Treatment, Time
View SamplesIdentification of genes regulated by the transcription factor HNF4a2
HNF4alpha reduces proliferation of kidney cells and affects genes deregulated in renal cell carcinoma.
No sample metadata fields
View SamplesLactic acidosis and hypoxia are two prominent tumor microenvironmental stresses that are both known to exert important influences on gene expression and phenotypes of cancer cells. But very little is known about the cross-talk and interaction between these two stresses. We performed gene expression analysis of MCF7 cells exposed to lactic acidosis, hypoxia and combined lactic acidosis and hypoxia. We found the hypoxia response elicited under hypoxia was mostly abolished upon simultaneous exposure to lactic acidosis. The repression effects are due to loss of HIF-1 protein synthesis under lactic acidosis. In addition, we showed lactic acidosis strongly synergizes with hypoxia to activate the unfold protein response (UPR) and inflammation response which are highly similar to amino acid deprivation responses (AAR). The statistical factor analysis of hypoxia and lactic acidosis responses indicated that ATF4 locus, an important activator in the UPR/AAR pathway, is amplified in subsets of breast tumors and cancer cell lines. Varying ATF4 levels dramatically affect the ability to survive the post-stress recovery from hypoxia and lactic acidosis and may suggest its selection of ATF4 amplification in human cancers. These data suggest that lactic acidosis interacts with hypoxia by both inhibiting the canonical hypoxia response and while activating the UPR and inflammation response. Gain of ATF4 locus may offer survival advantages to allow successful adaptation to frequent fluctuations of oxygen and acidity in tumor microenvironment. Collectively, our studies have provided linkage between the short-term transcriptional responses to the long term selection of the DNA copy number alterations (CNAs) under tumor microenvironmental stresses.
Functional interaction between responses to lactic acidosis and hypoxia regulates genomic transcriptional outputs.
Cell line
View SamplesMetabolically active cells require robust mechanisms to combat oxidative stress. The cytoplasmic thioredoxin reductase/thioredoxin (Txnrd1/Txn1) system maintains reduced protein dithiols and provides electrons to some cellular reductases, including peroxiredoxins.
Cytoprotective Nrf2 pathway is induced in chronically txnrd 1-deficient hepatocytes.
Specimen part
View SamplesType I interferon-stimulated genes (ISGs) have critical roles in inhibiting virus replication and dissemination. Despite advances in understanding the molecular basis of ISG restriction, the antiviral mechanisms of many remain unclear. The 20 kDa ISG, ISG20, is a nuclear 3''-5''exonuclease with preference for single stranded RNA (ssRNA) and has been implicated in the IFN-mediated restriction of several RNA viruses. Although the exonuclease activity of ISG20 has been shown to degrade viral RNA in vitro, evidence has yet to be presented that virus inhibition in cells requires this activity. Here, we utilized a combination of an inducible, ectopic expression system and newly generated Isg20-/- mice to investigate mechanisms and consequences of ISG20-mediated restriction. Ectopically expressed ISG20 localized primarily to Cajal bodies in the nucleus and restricted replication of chikungunya and Venezuelan equine encephalitis viruses. Although restriction by ISG20 was associated with inhibition of translation of infecting genomic RNA, degradation of viral RNAs was not observed. Instead, translation inhibition of viral RNA was associated with ISG20-induced upregulation of over 100 other genes, many of which encode known antiviral effectors. ISG20 modulated the production of IFIT1, an ISG that suppresses translation of alphavirus RNAs. Consistent with this observation, the pathogenicity of IFIT1-sensitive alphaviruses was increased in Isg20-/- mice compared to wild-type viruses, but not in ISG20 ectopic-expressing cells. Our findings establish an indirect role for ISG20 in the early restriction of RNA virus replication by regulating expressionof other ISGs that inhibit translation and possibly other activities in the replication cycle. Overall design: Two clones each of tet-inducible MEFs overexpressing eGFP (control), Isg20, and Isg20(D94G) were induced by tetracycline removal for 72 hours. rRNA was depleted with RiboMinus Eukaryote kit (Life Technologies) and prepared for Illumina directional 100bp paired-end HiSeq2000 reads.
The Interferon-Induced Exonuclease ISG20 Exerts Antiviral Activity through Upregulation of Type I Interferon Response Proteins.
Specimen part, Cell line, Subject
View SamplesHuman Mammalian Epithelial Cells (HMEC) were exposed to different environmental stresses, including hypoxia, lactic acidosis, the combination of hypoxia and lactic acidosis, lactosis , as well as acidosis.
The genomic analysis of lactic acidosis and acidosis response in human cancers.
No sample metadata fields
View SamplesContinuous contact with self-major histocompatibility complex ligands is essential for the survival of naive CD4 T cells. We have previously shown that the resulting tonic TCR signaling also influences their fate upon activation by increasing their ability to differentiate into induced regulatory T cells. To decipher the molecular mechanisms governing this process, microarray data comparing highly (Ly-6C-) and lowly (Ly-6C+) Self-reactive naive CD4 T cells were obtained.
Calcium-mediated shaping of naive CD4 T-cell phenotype and function.
Specimen part
View SamplesFoxo1 and Ebf1 deficiency leads to a similar disruption of normal B-cell development at the level of the common lymphoid progenitor (CLP). Both mouse strains display the existance of LY6D+ CLPs but a marked/complete lack of proB cells.
Positive intergenic feedback circuitry, involving EBF1 and FOXO1, orchestrates B-cell fate.
Specimen part
View SamplesImplantation is dependent on synchronized interactions between the conceptus and surrounding decidual cells but the involvement of clock genes in this process is not well understood. Circadian oscillations are predicated on transcriptional-translational feedback loops, which balance the activities of the transcriptional activators CLOCK and BMAL1 and repressors encoded by PER and CRY genes. Here we show that loss of PER2 expression silences circadian oscillations in decidualizing human endometrial stromal cells (HESCs). Downregulation was preceded by reduced CLOCK binding to a noncanonical E-box enhancer in the PER2 promoter and occurred between 12 - 24 h after exposure to a deciduogenic stimulus. RNA sequencing revealed that premature inhibition of PER2 by siRNA knockdown leads to a grossly disorganised decidual response. Gene ontology analysis highlighted a preponderance of cell cycle regulators amongst the 1,121 genes perturbed upon PER2 knockdown. Congruently, PER2 inhibition abrogated mitotic expansion of differentiating HESCs by inducing cell cycle block at G2/M. Analysis of mid-luteal endometrial biopsies revealed an inverse correlation between PER2 transcript levels and the number of miscarriages in women suffering reproductive failure. Thus, PER2 synchronizes mitotic expansion of HESCs with a periodic decidual gene expression; uncoupling of these events may cause persistent pregnancy failure. Overall design: Endometrial mRNA profiles of paired control (siRNA-NT) and siRNA-PER2 were generated by deep sequencing, in triplicate using Illumina
The clock protein period 2 synchronizes mitotic expansion and decidual transformation of human endometrial stromal cells.
No sample metadata fields
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