To exert regulatory function, miRNAs guide Argonaute (AGO) proteins to partially complementary sites on target RNAs. Crosslinking and immunoprecipitation (“re state-of-the-art to map AGO binding sites, but assigning the targeting miRNA to these sites relies on bioinformatics predictions and is therefore indirect. To directly and unambiguously identify miRNA:target site interactions, we modified our CLIP methodology in C. elegans to experimentally ligate miRNAs to their target sites. Unexpectedly, ligation reactions also occurred in absence of the exogenous ligase. Our in vivo dataset and re-analysis of published mammalian AGO-CLIP data for miRNA-chimeras yielded >17,000 miRNA:target site interactions. Analysis of interactions and extensive experimental validation of chimera-discovered targets of viral miRNAs suggest that our strategy identifies canonical, non-canonical, and non-conserved miRNA interactions. Our data suggest that ~80% of miRNA:targets have perfect or partial seed complementarity. In summary, analysis of miRNA:target chimeras enables the systematic, context-specific, in vivo discovery of miRNA interactions. Overall design: In vivo PAR-CLIP basically as described previously (Jungkamp et al. 2011) using GFP-tagged ALG-1 expressing worms in L3 stage. Worm lysate was treated with RNase T1. Following immunoprecipitation and a second RNase T1 digest, it was proceeded as described in Hafner et al. 2010. For the modified iPAR-CLIP ligation samples and its control samples immuno-purified complexes were treated with PNK phospathase minus, subjected to ligation with T4 RNA ligase/no ligase added and subsequently phosphorylated with PNK. Protein purification and RNA library preparation essentially as described in Hafner et al., but with the selection of longer RNA products.
Unambiguous identification of miRNA:target site interactions by different types of ligation reactions.
Specimen part, Subject
View SamplesDuring early development, the correct establishment of the body axes is a critical step. The anterior pole of the mouse embryo is established when Distal Visceral Endoderm (DVE) cells migrate to form the Anterior Visceral Endoderm (AVE). Asymmetrical expression of Lefty1, Cerl and Dkk determines the direction of DVE migration and the future anterior side. Besides being implicated in the establishment of Anterior-Posterior axis the AVE has also been correlated with anterior neural specification. In order to better understand the role of the AVE in these processes, this cell population was isolated using a cerlP-EGFP transgenic mouse line, and a differential screening was performed using Affymetrix GeneChip technology. From this differential screening, 175 genes were found to be upregulated in the AVE, whereas 35 genes were upregulated in the Proximal-posterior sample. Using DAVID, here we characterize the AVE cell population regarding cellular component, molecular function and biological processes. Among the genes that were found to be upregulated in the AVE, several novel genes with expression in the AVE were identified. Four of the identified transcripts displaying high-fold change were further characterized by in situ hybridization in early stages of development in order to validate the screening. From those four selected genes, ADTK1 was chosen to be functionally characterized by targeted inactivation in ES cells. ADTK1 encodes for an unknown serine/threonine kinase. ADTK null mutants present short limbs and defects in the eye and ear. Taken together, these data point to the importance of reporting novel genes present in the AVE.
Identification and functional analysis of novel genes expressed in the Anterior Visceral Endoderm.
Specimen part
View SamplesDouble-stranded RNA (dsRNA) can enter different pathways in mammalian cells, including sequence-specific RNA interference, sequence-independent interferon response and editing by adenosine deaminases. To assess the potential of expressed dsRNA to induce interferon stimulated genes in somatic cells, we performed microarray analysis of HEK293 and HeLa cells transfected with a MosIR plasmid expressing an mRNA with a long inverted repeat structure in its 3UTR (MosIR) or with a parental MosIR plasmid (without inverted repeat) as a control.
dsRNA expression in the mouse elicits RNAi in oocytes and low adenosine deamination in somatic cells.
Specimen part
View SamplesAnalysis of H292 cells infected with Mycoplasma hyorhinis. Mycoplasma infection reduces the cytotoxic effect of Nutlin3 on H292 cells. The results provide insight into molecular mechanisms underlying the response of H292 cells to Nutlin3.
Mycoplasma hyorhinis reduces sensitivity of human lung carcinoma cells to Nutlin-3 and promotes their malignant phenotype.
Specimen part, Cell line
View SamplesTo identify the genes regulated by androgen receptor (AR), we performed the profiling array analysis on the CWR22Rv1 cells and determined the differentially expressed genes upon the knockdown of AR.
The histone demethylase KDM3A regulates the transcriptional program of the androgen receptor in prostate cancer cells.
Cell line
View SamplesElimination of peripheral retinal axons leads to changes in gene expression in both visual and somatosensory thalamic neurons.
Prenatal thalamic waves regulate cortical area size prior to sensory processing.
Specimen part
View SamplesThis SuperSeries is composed of the SubSeries listed below.
The mammalian TRIM-NHL protein TRIM71/LIN-41 is a repressor of mRNA function.
Specimen part, Cell line
View SamplesWe identify mammalian TRIM71 as repressor of mRNAs that inhibits translation and affects mRNA stability.
The mammalian TRIM-NHL protein TRIM71/LIN-41 is a repressor of mRNA function.
Cell line
View SamplesWe identify mammalian TRIM71 as repressor of mRNAs that inhibits translation and affects mRNA stability. In this data set we compare the expression profile of mouse ES upon Trim71 KD versus that of the parental cells.
The mammalian TRIM-NHL protein TRIM71/LIN-41 is a repressor of mRNA function.
Specimen part
View SamplesHepatitis C virus (HCV) infection is a major cause of chronic liver disease worldwide. The current standard therapy for chronic hepatitis C (CHC) consists of a combination of pegylated IFN alpha (pegIFN-alpha) and ribavirin. It achieves a sustained viral clearance in only 5060% of patients. To learn more about molecular mechanisms underlying treatment failure, we investigated IFN-induced signaling in paired liver biopsies collected from CHC patients before and after administration of pegIFN-alpha. In patients with a rapid virological response to treatment, pegIFN-alpha induced a strong up-regulation of IFN-stimulated genes (ISGs). As shown previously, nonresponders had high expression levels of ISGs before therapy. Analysis of posttreatment biopsies of these patients revealed that pegIFN-alpha did not induce expression of ISGs above the pretreatment levels. In accordance with ISG expression data, phosphorylation, DNA binding, and nuclear localization of STAT1 indicated that the IFN signaling pathway in nonresponsive patients is preactivated and refractory to further stimulation. Some features characteristic of nonresponders were more accentuated in patients infected with HCV genotypes 1 and 4 compared with genotypes 2 and 3, providing a possible explanation for the poor response of the former group to therapy. Taken together with previous findings, our data support the concept that activation of the endogenous IFN system in CHC not only is ineffective in clearing the infection but also may impede the response to therapy, most likely by inducing a refractory state of the IFN signaling pathway.
Interferon signaling and treatment outcome in chronic hepatitis C.
No sample metadata fields
View Samples