DNA methylation is an important epigenetic control mechanism that has been shown to be associated with gene silencing through the course of development, maturation and aging. However, only limited data are available regarding the relationship between methylation and gene expression in human development. We analyzed the methylomes and transcriptomes of three human fetal liver samples (gestational age 20-22 weeks) and three adult human liver samples. Genes whose expression differed between fetal and adult numbered 7,673. Adult overexpression was associated with metabolic pathways and, in particular, cytochrome P450 enzymes, while fetal overexpression reflected enrichment for DNA replication and repair. Analysis for DNA methylation using the Illumina Infinium 450K HumanMethylation BeadChip showed that 42% of the quality filtered 426,154 methylation sites differed significantly between adult and fetal tissue (q0.05). Differences were small; 69% of the significant sites differed in their mean methylation beta value by 0.2. There was a trend among all sites toward higher methylation in the adult samples with the most frequent difference in beta being 0.1. Characterization of the relationship between methylation and expression revealed a clear difference between fetus and adult. Methylation of genes overexpressed in fetal liver showed the same pattern as seen for genes that were similarly expressed in fetal and adult liver. In contrast, adult overexpressed genes showed fetal hypermethylation that differed from the similarly expressed genes. An examination of gene region-specific methylation showed that sites proximal to the transcription start site or within the first exon with a significant fetal-adult difference in beta (>0.2) showed an inverse relationship with gene expression. Nearly half of the CpGs in human liver show a significant difference in methylation comparing fetal and adult samples. Sites proximal to the transcription start site or within the first exon that show a transition from hypermethylation in the fetus to hypomethylation or intermediate methylation in the adult are associated with inverse changes in gene expression. In contrast, increases in methylation going from fetal to adult are not associated with fetal-to-adult decreased expression. These findings indicate fundamentally different roles for and/or regulation of DNA methylation in human fetal and adult liver.
Patterns of gene expression and DNA methylation in human fetal and adult liver.
Sex, Age, Specimen part
View SamplesPseudomonas aeruginosa chronically colonizes the lungs of individuals with CF, where it reaches high cell densities and produces a battery of virulence factors. Upon infection, a single strain of P. aeruginosa can colonize an individuals lungs throughout his or her lifetime. To understand the evolution of P. aeruginosa during chronic lung infection, we conducted both genotypic and phenotypic analyses on clinical isogenic strains obtained from the lungs of three different individuals with CF. These strains were isolated over a period of approximately ten years and possess phenotypes that are commonly observed in isolates from the CF lung, such as the antibiotic resistant dwarf and mucoid phenotypes. Microarray analyses were carried out on isolates grown in a chemically defined medium that mimics the nutritional environment of the CF lung, synthetic CF sputum medium (SCFM).
Parallel evolution in Pseudomonas aeruginosa over 39,000 generations in vivo.
Time
View SamplesThe goal of this study was to determine the effects of a well-characterized anti-androgen, abiraterone acetate, and a suspected human anti-androgen, di-n-butyl phthalate (DBP) on the androgenic function of human fetal testis. Human fetal testis was xenografted into the renal subcapsular space of castrated male athymic nude mice. Hosts were treated with hCG to stimulate testosterone production in the xenografts, and were concurrently treated with either abiraterone acetate or DBP. While abiraterone acetate (14 d, 75 mg/kg/d p.o.) dramatically reduced testosterone and the weights of androgen-sensitive host organs, DBP (14 d, 500 mg/kg/d p.o.) had no effect on androgenic endpoints.
Differential response to abiraterone acetate and di-n-butyl phthalate in an androgen-sensitive human fetal testis xenograft bioassay.
Specimen part
View SamplesTo identify potential targets of miR-34a, we performed transcriptional profiling on proneural TS543 GBM cells, focusing on mRNAs whose levels decreased in response to miR-34a transfection as compared to control oligonucleotide.
miR-34a repression in proneural malignant gliomas upregulates expression of its target PDGFRA and promotes tumorigenesis.
Cell line, Treatment
View SamplesComparison of polysomal profiles of murine adult olig2 cortical progenitors, murine tumor olig2 cells derived from hPDGF-B-driven glioblastomas, and murine olig2 proliferative recruited glioma cells contributing to the tumor mass but not derived from the cell of origin
Recruited cells can become transformed and overtake PDGF-induced murine gliomas in vivo during tumor progression.
Specimen part
View SamplesLarge-scale cancer genomics projects are profiling hundreds of tumors at multiple molecular layers, including copy number, mRNA and miRNA expression, but the mechanistic relationships between these layers are often excluded from computational models. We developed a supervised learning framework for integrating molecular profiles with regulatory sequence information to reveal regulatory programs in cancer, including miRNA-mediated regulation. We applied our approach to 320 glioblastoma profiles and identified key miRNAs and transcription factors as common or subtype-specific drivers of expression changes. We confirmed that predicted gene expression signatures for proneural subtype regulators were consistent with in vivo expression changes in a PDGF-driven mouse model. We tested two predicted proneural drivers, miR-124 and miR-132, both underexpressed in proneural tumors, by overexpression in neurospheres and observed a partial reversal of corresponding tumor expression changes. Computationally dissecting the role of miRNAs in cancer may ultimately lead to small RNA therapeutics tailored to subtype or individual.
Inferring transcriptional and microRNA-mediated regulatory programs in glioblastoma.
Cell line
View SamplesTumor associated macrophages are contributing to local invasion, angiogensis, and metastasis during the progression of many kinds of tumor including glioma
Oligodendrocyte progenitor cells promote neovascularization in glioma by disrupting the blood-brain barrier.
Specimen part
View SamplesPTPRD is a tumor suppressor of glioma that is frequently co-deleted with CDKN2A/p16. We show that Ptprd and p16 cooperate to promote gliomagenesis in the RCAS PDGFB / Nestin tv-A glioma mouse model.
Loss of the tyrosine phosphatase PTPRD leads to aberrant STAT3 activation and promotes gliomagenesis.
Specimen part
View SamplesSo far, the annotation of translation initiation sites (TISs) has been based mostly upon bioinformatics rather than experimental evidence. We adapted ribosomal footprinting to puromycin-treated cells to generate a transcriptome-wide map of TISs in a human monocytic cell line. A neural network was trained on the ribosomal footprints at previously annotated AUG translation initiation codons (TICs), and used for the ab initio prediction of TISs in 5062 transcripts with sufficient sequence coverage. Functional interpretation suggested 2994 novel upstream open reading frames (uORFs) in the 5´ UTR (924 AUG, 2070 near-cognate codons), 1406 uORFs overlapping with the coding sequence (116 AUG, 1290 near-cognate) and 546 N-terminal protein extensions (6 AUG, 540 near-cognate). The TIS detection method was validated on the basis of previously published alternative TISs and uORFs. On average, TICs in newly annotated TISs were significantly more conserved among primates than control codons, both for AUGs (p<10-10) and near-cognate codons (p=3.8×10-3). The derived transcriptome-wide map of novel candidate TISs will help to explain how human proteome diversity is influenced by alternative translation initiation and regulation. Overall design: Examination of translational initiation in human cell lines using ribosomal footprinting
Genome-wide search for novel human uORFs and N-terminal protein extensions using ribosomal footprinting.
Cell line, Treatment, Subject
View SamplesTransformation of follicular lymphoma (FL) to a more aggressive disease is associated with rapid progression and death. Existing molecular markers for transformation are few and their clinical impact is limited. Here, we report on a whole-genome study of DNA copy numbers and gene expression profiles in serial FL biopsies. We identified 698 genes with high correlation between gene expression and copy number and the molecular network most enriched for these cis-associated genes. This network includes 14 cis-associated genes directly related to the NFB pathway. For each of these 14 genes, the correlated NFB target genes were identified and corresponding expression scores defined. The scores for six of the cis-associated NFB pathway genes (BTK, IGBP1, IRAK1, ROCK1, TMED7-TICAM2 and TRIM37) were significantly associated with transformation. The results suggest that genes regulating B-cell survival and activation are involved in transformation of FL
Whole-genome integrative analysis reveals expression signatures predicting transformation in follicular lymphoma.
Specimen part
View Samples