MicroRNAs are endogenously expressed small non-coding RNAs that regulate gene expression on the posttranscriptional level. The miR-17-92 cluster (encoding miR-17, -18a, -19a/b, -20a and miR-92a) is highly expressed in tumor cells and is up-regulated by ischemia. Whereas miR-92a was recently identified as negative regulator of angiogenesis, the specific functions of the other members of the cluster are less clear. Here we demonstrate that overexpression of miR-17, -18a, -19a and -20a significantly inhibited 3D spheroid sprouting in vitro, whereas inhibition of miR-17, -18a and -20a augmented endothelial cell (EC) sprout formation. Inhibition of miR-17 and miR-20a in vivo using antagomirs significantly increased the number of perfused vessels in matrigel plugs, whereas antagomirs, that specifically target miR-18a and miR-19a were less effective. However, systemic inhibition of miR-17/20 did not affect tumor angiogenesis. Further mechanistic studies showed that miR-17/20 targets several pro-angiogenic genes. Specifically, Janus kinase 1 (Jak1) was shown to be a direct target of miR-17. In summary, we show that miR-17/20 exhibit a cell intrinsic anti-angiogenic activity in ECs. Inhibition of miR-17/20 specifically augmented neovascularization of matrigel plugs, but did not affect tumor angiogenesis indicating a context-dependent regulation of angiogenesis by miR-17/20 in vivo.
Members of the microRNA-17-92 cluster exhibit a cell-intrinsic antiangiogenic function in endothelial cells.
Specimen part
View SamplesClass IIa histone deacetylases (HDACs) are signal-responsive regulators of gene expression involved in vascular homeostasis. To investigate the differential role of class IIa HDACs for the regulation of angiogenesis, we used siRNA to specifically suppress the individual HDAC isoenzymes. Among the HDAC isoforms tested, silencing of HDAC5 exhibited a unique pro-angiogenic effect evidenced by increased endothelial cell migration, sprouting and tube formation. Consistently, overexpression of HDAC5 decreased sprout formation, indicating that HDAC5 is a negative regulator of angiogenesis. The anti-angiogenic activity of HDAC5 was independent of MEF2 binding and its deacetylase activity, but required a nuclear localization indicating that HDAC5 might affect the transcriptional regulation of gene expression. To identify putative HDAC5 targets, we performed microarray expression analysis. Silencing of HDAC5 increased the expression of fibroblast growth factor 2 (FGF2) and angiogenic guidance factors including Slit2. Antagonization of FGF2 or Slit2 reduced sprout induction in response to HDAC5 siRNA. ChIP assays demonstrate that HDAC5 binds to the promoter of FGF2 and Slit2. In summary, HDAC5 represses angiogenic genes, like FGF2 and Slit2, which causally contribute to capillary-like sprouting of endothelial cells. The de-repression of angiogenic genes by HDAC5 inactivation may provide a useful therapeutic target for induction of angiogenesis.
HDAC5 is a repressor of angiogenesis and determines the angiogenic gene expression pattern of endothelial cells.
Specimen part
View SamplesMyeloid Angiogenic Cells (MACs) were infected with the intracellular, bacterial pathogen Bartonella henselae (B.h.). Infected cells were seeded onto Matrigel coated plates. While uninfected cells showed no phenotypic changes and died over time, infected cells showed strong phenotypic changes and developed into complex 2D chord networks over the course of long term culture (eg 49d). To examine the changes in gene expression associated with the development of the B.h.dependent chord formation phenotype, RNA was isolated from MACs shortly after isolation (d4) and from cells of the chord structures (+B.h. Matrigel). As primary endothelial cells are also know to form chord networks when cultured on Matrigel, a sample of human umbilical vein endothelial cells (HUVECs) cultured on Matrigel for 12hr was also included in the analysis as a control.
Reprogramming of myeloid angiogenic cells by Bartonella henselae leads to microenvironmental regulation of pathological angiogenesis.
Specimen part, Subject, Time
View SamplesCircadian regulation of gene expression in central and peripheral tissue has been studied in mice. The biomedical implications of this findings led us to the development of a model in which to study the circadian mechanisms underlying primate physiology.
Twenty-four-hour rhythmic gene expression in the rhesus macaque adrenal gland.
No sample metadata fields
View SamplesHuman iPS cells derived from normal and Fragile-X fibroblasts in order to assess the capability of Fragile-X iPS cells to be used as a model for different aspects of Fragile-X syndrome. Microarry analysis used to compare global gene expression between human ES cells, the normal and the mutant iPS cells and the original fibroblasts, to demonstrate that the overall reprogramming process succeeded, and that the FX-iPS cells are fully reprogrammed cells.
Differential modeling of fragile X syndrome by human embryonic stem cells and induced pluripotent stem cells.
Specimen part, Disease, Cell line
View SamplesBACKGROUND: Climate change will lead in the future to an occurrence of heat waves with a higher frequency and duration than observed today, which has the potential to cause severe damage to seedlings of temperate maize genotypes. In this study, we aimed to (I) assess phenotypic variation for heat tolerance of temperate European Flint and Dent maize inbred lines, (II) investigate the transcriptomic response of temperate maize to linearly increasing heat levels and, (III) identify genes associated with heat tolerance in a set of genotypes with contrasting heat tolerance behaviour. RESULTS: Strong phenotypic differences with respect to heat tolerance were observed between the examined maize inbred lines on a multi-trait level. We identified 607 heat responsive genes as well as 39 heat tolerance genes. CONCLUSION: Our findings indicate that individual inbred lines developed different genetic mechanisms in response to heat stress. We applied a novel statistical approach enabling the integration of multiple genotypes and stress levels in the analysis of abiotic stress expression studies. Overall design: Identifcation of differentially expressed genes between 8 genotypes and 3 heat levels
Genome-wide expression profiling and phenotypic evaluation of European maize inbreds at seedling stage in response to heat stress.
Specimen part, Subject
View SamplesThe in-vitro analysis of the hypomethylation of the imprinting control region 1 (ICR1) within the IGF2/H19 locus is challenged by the mosaic distribution of the epimutation in tissues from children with Silver-Russell syndrome (SRS).
Decreased expression of cell proliferation-related genes in clonally derived skin fibroblasts from children with Silver-Russell syndrome is independent of the degree of 11p15 ICR1 hypomethylation.
Specimen part, Disease
View SamplesAssessment of the putative differential gene expression profiles in high osmolality-treated bovine nucleus pulposus intervertebral disc cells for a short (5 h) and a long (24 h) time period. Identification of novel genes up- or down-regulated as an early or a late response to hyperosmotic stress.
Deficiency in the α1 subunit of Na+/K+-ATPase enhances the anti-proliferative effect of high osmolality in nucleus pulposus intervertebral disc cells.
Specimen part
View SamplesInfection with Nippostrongylus brasiliensis results in persistent changes to the lung environment. Cytokine profiling reveals a sustained increase in both Th1 and Th2 transcripts. Cellular populations of macrophages display an alternative phenotype, with upregulation of YM1, Arg1, Mrc1 as well as Class II MHC. These alternatively activated alveolar macrophages (AAAMs) also increase drastically in number. Subsequent challenge with house dust mite (HDM) Dermatophagoides pteronyssinus shows a reduced allergic phenotype, with decreased fold changes in effector cell cytokines of both the Th1 and Th2 variety indicative of the new regulatory environment established in the lung by helminth infection. Histological examination of the lung environment reveals a significant decrease in eosinophila and reduced mucous production by bronchial epithelial cells.
Hookworm-induced persistent changes to the immunological environment of the lung.
No sample metadata fields
View SamplesThe ubiquitin proteasome system (UPS) is known to possess important regulatory functions in the immune response. To gain a better and first comprehensive insight into the mechanisms underlying the conversion of immature to mature DC in terms of the expression of UPS related genes, we undertook a comparative gene expression profiling during DC maturation in response to four different prototypic maturation stimuli.
Maturation of human dendritic cells is accompanied by functional remodelling of the ubiquitin-proteasome system.
No sample metadata fields
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