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Akhtar W.,Netherlands Cancer Institute | Pindyurin A.V.,Netherlands Cancer Institute | Pindyurin A.V.,Russian Academy of Sciences | De Jong J.,Netherlands Cancer Institute | And 9 more authors.
Nature Protocols | Year: 2014

The influence of local chromatin context on gene expression can be explored by integrating a transcription reporter at different locations in the genome as a sensor. Here we provide a detailed protocol for analyzing thousands of reporters integrated in parallel (TRIP) at a genome-wide level. TRIP is based on tagging each reporter with a unique barcode, which is used for independent reporter expression analysis and integration site mapping. Compared with previous methods for studying position effects, TRIP offers a 100-1,000-fold higher throughput in a faster and less-labor-intensive manner. The entire experimental protocol takes â ̂1/442 d to complete, with high-throughput sequencing and data analysis requiring an additional â ̂1/411 d. TRIP was developed by using transcription reporters in mouse embryonic stem (mES) cells, but because of its flexibility the method can be used to probe the influence of chromatin context on a variety of molecular processes in any transfectable cell line. © 2014 Nature America, Inc. Source

de Jong J.,Netherlands Cancer Institute | Akhtar W.,Netherlands Consortium for Systems Biology | Akhtar W.,Netherlands Cancer Institute | Badhai J.,Netherlands Cancer Institute | And 9 more authors.
PLoS Genetics | Year: 2014

The ability of retroviruses and transposons to insert their genetic material into host DNA makes them widely used tools in molecular biology, cancer research and gene therapy. However, these systems have biases that may strongly affect research outcomes. To address this issue, we generated very large datasets consisting of ~120000 to ~180000 unselected integrations in the mouse genome for the Sleeping Beauty (SB) and piggyBac (PB) transposons, and the Mouse Mammary Tumor Virus (MMTV). We analyzed ~80 (epi)genomic features to generate bias maps at both local and genome-wide scales. MMTV showed a remarkably uniform distribution of integrations across the genome. More distinct preferences were observed for the two transposons, with PB showing remarkable resemblance to bias profiles of the Murine Leukemia Virus. Furthermore, we present a model where target site selection is directed at multiple scales. At a large scale, target site selection is similar across systems, and defined by domain-oriented features, namely expression of proximal genes, proximity to CpG islands and to genic features, chromatin compaction and replication timing. Notable differences between the systems are mainly observed at smaller scales, and are directed by a diverse range of features. To study the effect of these biases on integration sites occupied under selective pressure, we turned to insertional mutagenesis (IM) screens. In IM screens, putative cancer genes are identified by finding frequently targeted genomic regions, or Common Integration Sites (CISs). Within three recently completed IM screens, we identified 7%-33% putative false positive CISs, which are likely not the result of the oncogenic selection process. Moreover, results indicate that PB, compared to SB, is more suited to tag oncogenes. © 2014 de Jong et al. Source

Wei Y.-N.,Chinese Academy of Sciences | Wei Y.-N.,University of Chinese Academy of Sciences | Hu H.-Y.,Chinese Academy of Sciences | Xie G.-C.,Chinese Academy of Sciences | And 7 more authors.
Genome Biology | Year: 2015

Background: In studies of development and aging, the expression of many genes has been shown to undergo drastic changes at mRNA and protein levels. The connection between mRNA and protein expression level changes, as well as the role of posttranscriptional regulation in controlling expression level changes in postnatal development and aging, remains largely unexplored. Results: Here, we survey mRNA and protein expression changes in the prefrontal cortex of humans and rhesus macaques over developmental and aging intervals of both species' lifespans. We find substantial decoupling of mRNA and protein expression levels in aging, but not in development. Genes showing increased mRNA/protein disparity in primate brain aging form expression patterns conserved between humans and macaques and are enriched in specific functions involving mammalian target of rapamycin (mTOR) signaling, mitochondrial function and neurodegeneration. Mechanistically, aging-dependent mRNA/protein expression decoupling could be linked to a specific set of RNA binding proteins and, to a lesser extent, to specific microRNAs. Conclusions: Increased decoupling of mRNA and protein expression profiles observed in human and macaque brain aging results in specific co-expression profiles composed of genes with shared functions and shared regulatory signals linked to specific posttranscriptional regulators. Genes targeted and predicted to be targeted by the aging-dependent posttranscriptional regulation are associated with biological processes known to play important roles in aging and lifespan extension. These results indicate the potential importance of posttranscriptional regulation in modulating aging-dependent changes in humans and other species. © 2015 Wei et al. Source

Bozek K.,Chinese Academy of Sciences | Bozek K.,Max Planck Institute for Evolutionary Anthropology | Wei Y.,Chinese Academy of Sciences | Yan Z.,Chinese Academy of Sciences | And 15 more authors.
Neuron | Year: 2015

Lipids are prominent components of the nervous system. Here we performed a large-scale mass spectrometry-based analysis of the lipid composition of three brain regions as well as kidney and skeletal muscle of humans, chimpanzees, rhesus macaques, and mice. The human brain shows the most distinct lipid composition: 76% of 5,713 lipid compounds examined in our study are either enriched or depleted in the human brain. Concentration levels of lipids enriched in the brain evolve approximately four times faster among primates compared with lipids characteristic of non-neural tissues and show further acceleration of change in human neocortical regions but not in the cerebellum. Human-specific concentration changes are supported by human-specific expression changes for corresponding enzymes. These results provide the first insights into the role of lipids in human brain evolution. © 2015 Elsevier Inc. Source

Sergiev P.V.,Moscow State University | Golovina A.Y.,Moscow State University | Osterman I.A.,Moscow State University | Nesterchuk M.V.,Skolkovo Institute for Science and Technology | And 11 more authors.
Journal of Molecular Biology | Year: 2015

N6-methyladenosine (m6A) is ubiquitously present in the RNA of living organisms from Escherichia coli to humans. Methyltransferases that catalyze adenosine methylation are drastically different in specificity from modification of single residues in bacterial ribosomal or transfer RNA to modification of thousands of residues spread among eukaryotic mRNA. Interactions that are formed by m6A residues range from RNA-RNA tertiary contacts to RNA-protein recognition. Consequences of the modification loss might vary from nearly negligible to complete reprogramming of regulatory pathways and lethality. In this review, we summarized current knowledge on enzymes that introduce m6A modification, ways to detect m6A presence in RNA and the functional role of this modification everywhere it is present, from bacteria to humans. © 2015 Elsevier Ltd. Source

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