Gene expression profiles from the aortic arch of Ldlr-/-Apob100/100 Mttpflox/flox Mx1-Cre mice at different stages of atherosclerosis development
Transcriptional profiling uncovers a network of cholesterol-responsive atherosclerosis target genes.
Age, Specimen part
View SamplesThe spatial and temporal control of Hox gene transcription is essential for patterning the vertebrate body axis. Although this process involves changes in histone posttranslational modifications, the existence of particular three-dimensional (3D) architectures remained to be assessed in vivo. Using high-resolution chromatin conformation capture methodology, we examined the spatial configuration of Hox clusters in embryonic mouse tissues where different Hox genes are active. When the cluster is transcriptionally inactive, Hox genes associate into a single 3D structure delimited from flanking regions. Once transcription starts, Hox clusters switch to a bimodal 3D organization where newly activated genes progressively cluster into a transcriptionally active compartment. This transition in spatial configurations coincides with the dynamics of chromatin marks, which label the progression of the gene clusters from a negative to a positive transcription status. This spatial compartmentalization may be key to process the collinear activation of these compact gene clusters.
The dynamic architecture of Hox gene clusters.
Specimen part
View SamplesThe functional shift of quiescent endothelial cells into tip cells that migrate and stalk cells that proliferate is a key event during sprouting angiogenesis. We previously showed that the sialomucin CD34 is expressed in a small subset of cultured endothelial cells and that these cells extend filopodia: a hallmark of tip cells in vivo. In the present study, we characterized endothelial cells expressing CD34 in endothelial monolayers in vitro. We found that CD34-positive human umbilical vein endothelial cells show low proliferation activity and increased mRNA expression of all known tip cell markers, as compared to CD34- negative cells. Genome-wide mRNA profiling analysis of CD34-positive endothelial cells demonstrated enrichment for biological functions related to angiogenesis and migration, whereas CD34-negative cells were enriched for functions related to proliferation. In addition, we found an increase or decrease of CD34-positive cells in vitro upon exposure to stimuli that enhance or limit the number of tip cells in vivo, respectively. Our findings suggest cells with virtually all known properties of tip cells are present in vascular endothelial cell cultures and that they can be isolated based on expression of CD34. This novel strategy may open alternative avenues for future studies of molecular processes and functions in tip cells in angiogenesis.
CD34 marks angiogenic tip cells in human vascular endothelial cell cultures.
Specimen part, Subject
View SamplesTo assess the mechanism by which adult germ cells induce cbs-1 expression in the intestine at cold temperature, we performed transcriptome analysis of extruded germ lines from wild-type worms upon iff-1 knockdown or temperature increase Overall design: We extruded germ line of iff-1 RNAi-treated worms at 15°C and empty vector (EV) RNAi-treated worms at 20°C and compared to the germ line of EV RNAi-treated worms at 15°C.
Prostaglandin signals from adult germ stem cells delay somatic aging of <i>Caenorhabditis elegans</i>.
Specimen part, Subject
View SamplesWFS1 gene is coding protein with unknown function but its functional deficiency causes different neuropsychiatric and neuroendocrine syndromes. In the present study we aimed to find the functional networks influenced by the Wfs1 deficiency in the hypothalamus. We performed gene expression profiling (Mouse Gene 1.0 ST Arrays) in Wfs1 deficient mice (ko). Modified t-statistics was used for comparison of groups (wt vs ko). Functional annotation of the alterations in RNA levels was performed with Ingenuity Pathway Analysis. 305 genes were differentially expressed with nominal p-value less than 0.01. FDR adjusted p-values were significant (0.007) only for two genes C4b (t=9.66) and Wfs1 (t=-9.03). However, several genes related to the G-protein signalling were very close to the FDR adjusted significance. For instance, Rgs4 (regulator of G-protein signalling 4) was down-regulated (-0.34, t=-5.4) in Wfs1 deficient mice. Changes in Rgs4 and C4B expression were confirmed by QRT-PCR. In humans, Rgs4 is in the locus for bipolar disease (BPD) and its expression is down-regulated in BPD. C4b is the gene related to the neurodegenerative diseases. In conclusion, hypothalamic gene expression profiling indicates alterations in some functionally relevant molecular pathways explaining the clinical syndrome in the Wolfram syndrome patients.
Hypothalamic gene expression profile indicates a reduction in G protein signaling in the Wfs1 mutant mice.
Specimen part
View SamplesPlants are sessile organisms and therefore must sense and respond to changes of their surrounding conditions such as ambient temperature, which vary diurnally and seasonally. It is not yet clear how plants sense temperature and integrate this information into their development. We have previously shown that H2A.Z-nucleosomes are evicted in response to warmer temperatures. It is not clear however, whether the link between transcriptional responsiveness and changes in H2A.Z binding in context of temperature shifts is a global trend that can be seen throughout the genome, or the phenomenon is specific to a specialised set of temperature-responsive genes. In addition to the role of H2A.Z-nucleosome dynamics in the transcriptional response to temperature, it was shown that genes strongly misregulated in the h2a.z mutant are enriched for gene categories involved in response to multiple environmental cues. This suggests that H2A.Z could be implicated in the transcriptional response to various environmental inputs, raising the question: What brings the specificity of H2A.Z dynamics in response to temperature? To address this question we have profiled H2A.Z-nucleosome occupancy genome wide (using ChIP-seq) during a time course after temperature variation and compared its dynamics to transcriptional changes. We identified a fast, targeted and transient eviction of H2A.Z associated with transcriptional activation in response to temperature for a few hundreds genes. This eviction is associated with a reduction of the stability of the nucleosome. Moreover the genes with a fast H2A.Z eviction were strongly enriched in heat shock elements in their promoter and we observed a strong association between HSF1 binding and H2AZ eviction at warm temperature. These results highlight the importance of the interplay between transcription factors and chromatin to allow a controlled and dynamics response to temperature. Overall design: RNA-seq were generated in duplicate for seedlings shifted to warm temperature
Transcriptional Regulation of the Ambient Temperature Response by H2A.Z Nucleosomes and HSF1 Transcription Factors in Arabidopsis.
Subject
View SamplesPlants are sessile organisms and therefore must sense and respond to changes of their surrounding conditions such as ambient temperature, which vary diurnally and seasonally. It is not yet clear how plants sense temperature and integrate this information into their development. We have previously shown that H2A.Z-nucleosomes are evicted in response to warmer temperatures. It is not clear however, whether the link between transcriptional responsiveness and changes in H2A.Z binding in context of temperature shifts is a global trend that can be seen throughout the genome, or the phenomenon is specific to a specialised set of temperature-responsive genes. In addition to the role of H2A.Z-nucleosome dynamics in the transcriptional response to temperature, it was shown that genes strongly misregulated in the h2a.z mutant are enriched for gene categories involved in response to multiple environmental cues. This suggests that H2A.Z could be implicated in the transcriptional response to various environmental inputs, raising the question: What brings the specificity of H2A.Z dynamics in response to temperature? To address this question we have profiled H2A.Z-nucleosome occupancy genome wide (using ChIP-seq) during a time course after temperature variation and compared its dynamics to transcriptional changes. We identified a fast, targeted and transient eviction of H2A.Z associated with transcriptional activation in response to temperature for a few hundreds genes. This eviction is associated with a reduction of the stability of the nucleosome. Moreover the genes with a fast H2A.Z eviction were strongly enriched in heat shock elements in their promoter and we observed a strong association between HSF1 binding and H2AZ eviction at warm temperature. These results highlight the importance of the interplay between transcription factors and chromatin to allow a controlled and dynamics response to temperature. Overall design: RNA-seq were generated in duplicate for seedlings shifted to warm temperature
Transcriptional Regulation of the Ambient Temperature Response by H2A.Z Nucleosomes and HSF1 Transcription Factors in Arabidopsis.
Subject
View SamplesMammalian genomes contain numerous DNA elements with potential transcription regulatory function but unknown target genes. We used transgenic, gain-of-function mice with an ectopic copy of the beta-globin locus control region (LCR) to better understand how regulatory elements dynamically search the genome for target genes. We find that the LCR samples a restricted nuclear sub-volume in which it forms preferential contacts with genes controlled by shared transcription factors. One contacted gene, betah1, located on another chromosome, is upregulated, providing genetic demonstration that mammalian enhancers can function between chromosomes. Upregulation is not pan-cellular but confined to selected jackpot cells significantly enriched for inter-chromosomal LCR-betah1 interactions. This implies that long-range DNA contacts are relatively stable and cell-specific and, when functional, cause variegated expression. We refer to this as spatial effect variegation (SEV). The data provide a dynamic and mechanistic framework for enhancer action, important for assigning function to the one- and three-dimensional structure of DNA.
Variegated gene expression caused by cell-specific long-range DNA interactions.
Specimen part, Disease
View SamplesEwing sarcomas are characterized by the presence of EWS/ETS fusion genes in the absence of other recurrent genetic alterations and mechanisms of tumor heterogeneity that contribute to disease progression remain unclear. Mutations in the Wnt/beta-catenin pathway are rare in Ewing sarcoma but the Wnt pathway modulator LGR5 is often highly expressed, suggesting a potential role for the axis in tumor pathogenesis. We evaluated beta-catenin and LGR5 expression in Ewing sarcoma cell lines and tumors and noted marked intra- and inter-tumor heterogeneity. Tumors with evidence of active Wnt/beta-catenin signaling were associated with increased incidence of tumor relapse and worse overall survival. Paradoxically, RNA sequencing revealed a marked antagonism of EWS/ETS transcriptional activity in Wnt/beta-catenin activated tumor cells. Consistent with this, Wnt/beta-catenin activated cells displayed a phenotype that was reminiscent of Ewing sarcoma cells with partial EWS/ETS loss of function. Specifically, activation of Wnt/beta-catenin induced alterations to the actin cytoskeleton, acquisition of a migratory phenotype and up regulation of EWS/ETS-repressed genes. Notably, activation of Wnt/beta-catenin signaling led to marked induction of tenascin C (TNC), an established promoter of cancer metastasis, and an EWS/ETS-repressed target gene. Loss of TNC function in Ewing sarcoma cells profoundly inhibited their migratory and metastatic potential. Our studies reveal that heterogeneous activation of Wnt/beta-catenin signaling in subpopulations of tumor cells contributes to phenotypic heterogeneity and disease progression in Ewing sarcoma. Significantly, this is mediated, at least in part, by inhibition of EWS/ETS fusion protein function that results in de-repression of metastasis-associated gene programs. Overall design: Differential gene expression in highly Wnt-responsive cells.
Activation of Wnt/β-Catenin in Ewing Sarcoma Cells Antagonizes EWS/ETS Function and Promotes Phenotypic Transition to More Metastatic Cell States.
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View SamplesTissue samples have been isolated during corornary artery by-pass grafting (CABG)surgery from the atheroscelrotic arterial wall (AAW, aortic root puncture for proxmal ligation of by-pass vessel), non-atherosclertoci arterial wall (NAAW, distal part of mammary artery used a graft for LAD), liver, skeletal muscle (Recturs m), pericardial mediastinal visceral fat) in CAD patients. Carotid lesions samples from 25 validation patients.
Multi-organ expression profiling uncovers a gene module in coronary artery disease involving transendothelial migration of leukocytes and LIM domain binding 2: the Stockholm Atherosclerosis Gene Expression (STAGE) study.
Specimen part
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