Aims to look at the targets of the bHLH transcription factor in Arabidopsis roots.
A basic helix-loop-helix transcription factor controls cell growth and size in root hairs.
Specimen part
View SamplesIntracranial aneurysms tend to form at bifurcation apices, where flow impingement causes high frictional force (or wall shear stress, WSS) and flow acceleration and deceleration that create positive and negative streamwise gradients in WSS (WSSG), respectively. In vivo, intracranial aneurysms initiate under high WSS and positive WSSG. Little is known about the responses of endothelial cells (ECs) to either positive or negative WSSG under high WSS conditions. We used cDNA microarrays to profile EC gene expression exposed to positive WSSG vs. negative WSSG for 24 hours in a flow chamber with converging and diverging channels, respectively. WSS varied between 3.5 and 28.4 Pa in each gradient channel. GO and biological pathway analysis indicated that positive WSSG favored proliferation, apoptosis, and extracellular matrix processing while decreasing expression of pro-inflammatory genes. A subset of characteristic genes was validated using qPCR: Genes for ADAMTS1, CKAP2 and NCEH1 had higher expression under positive WSSG compared to negative WSSG while TAGLN, THBS1, VCAM1, CCL2, and CSF2 had lower expression. To determine if these patterns of expression are also exhibited in vivo, we tested whether the extracellular matrix related protein ADAMTS1 and proliferation were modulated by positive WSSG during intracranial aneurysm initiation. An aneurysm was induced at the basiliar terminus in rabbits by bilateral carotid ligation. WSSG at the bifurcation was determined by computational fluid dynamic simulations from 3D angiography and mapped on immunofluorescence staining for ADAMTS1 and the proliferation marker, Ki-67. Endothelial ADAMTS1 protein and Ki-67 were significantly higher in regions with positive WSSG compared to adjacent sites where WSSG was negative. Our results indicate that WSSG can elicit distinct gene expression profiles in ECs. Increased matrix processing and high levels of proliferation under positive WSSG could contribute to intracranial aneurysm initiation by causing transient gaps in the endothelium or disrupting EC signals to smooth muscle cells.
Differential gene expression by endothelial cells under positive and negative streamwise gradients of high wall shear stress.
Specimen part
View SamplesChronic high flow can induce arterial remodeling, and this effect is mediated by endothelial cells (ECs) responding to wall shear stress (WSS). To assess how WSS above physiological normal levels affects ECs, we used DNA microarrays to profile EC gene expression under various flow conditions. Cultured bovine aortic ECs were exposed to no flow (0 Pa), normal WSS (2 Pa) and very high WSS (10 Pa) for 24 hrs. Very high WSS induced a distinct expression profile when compared to both no flow and normal WSS. Gene ontology and biological pathway analysis revealed that high WSS modulated gene expression in ways that promote an anti-coagulant, anti-inflammatory, proliferative and pro-matrix remodeling phenotype. A subset of characteristic genes was validated using quantitative polymerase chain reaction (qPCR): Very high WSS upregulated ADAMTS1, PLAU (uPA), PLAT (tPA) and TIMP3, all of which are involved in extracellular matrix processing, with PLAT and PLAU also contributing to fibrinolysis. Downregulated genes included chemokines CXCL5 and IL-8 and the adhesive glycoprotein THBS1 (TSP1). Expressions of ADAMTS1 and uPA proteins were assessed by immunhistochemistry in rabbit basilar arteries experiencing increased flow after bilaterial carotid artery ligation. Both proteins were significantly increased when WSS was elevated compared to sham control animals. Our results indicate that very high WSS elicits a unique transcriptional profile in ECs that favors particular cell functions and pathways that are important in vessel homeostasis under increased flow. In addition, we identify specific molecular targets that are likely to contribute to adaptive remodeling under elevated flow conditions.
Endothelial cells express a unique transcriptional profile under very high wall shear stress known to induce expansive arterial remodeling.
Specimen part
View SamplesDespite their different origin and function, both pollen tubes and root hairs share the same sort of apical growth mechanism, i.e., the spatially focused cell expansion at the very apex. Ion fluxes, membrane trafficking, the actin cytoskeleton and their interconnection via signaling networks have been identified as fundamental processes underlying this kind of growth. Several molecules involved in apical growth have been identified, but the genetic basis is far from being fully characterized. We have used Affymetrix Arabidopsis ATH1 GeneChips to obtain the expression profiles of isolated Arabidopsis root hairs. A comparison with the expression profile of flow-sorted pollen grains reveals an overlap in the expression of 4989 genes, which corresponds to 42% of the root hair transcriptome and 76% of the pollen transcriptome, respectively. Our comparison with transcriptional profiles of vegetative tissues by principal component analysis and hierarchical clustering shows a clear separation of these samples comprised of cell types with diffuse growth from the two cell types with apical growth. 277 genes are enriched and 49 selectively expressed, respectively, in root hairs and pollen. From this set of genes emerges an apical growth signature containing novel candidate genes for apical growth determination.
Transcriptional profiling of Arabidopsis root hairs and pollen defines an apical cell growth signature.
Specimen part
View SamplesTo compare hepatic gene expression in conditional Keap1 knockout (Alb-Cre:Keap1(flox/-)) and genetic control mice. Disruption of Keap1-mediated repression of Nrf2 signaling was expected to result in increased expression of Nrf2-regulated genes.
Genetic or pharmacologic amplification of nrf2 signaling inhibits acute inflammatory liver injury in mice.
No sample metadata fields
View SamplesGcn5/PCAF double knockout (dKO) leads to loss of the global H3K9ac. RNA-Seq was performed to define the changes of gene expression in response to Gcn5/PCAF deletion and H3K9ac loss Overall design: PCAF-/-;Gcn5f/D MEFs were infected with retroviral Cre to delete Gcn5 to generate Gcn5/PCAF dKO cells, followed by RNA-Seq analysis using spike-in RNA as controls
Gcn5 and PCAF negatively regulate interferon-β production through HAT-independent inhibition of TBK1.
No sample metadata fields
View SamplesLarge inter-individual variance has been observed in sensitivity to drugs. To comprehensively decipher the genetic contribution to these variations in drug susceptibility, we present a genome-wide model utilizing human lymphoblastoid cell lines from the International HapMap consortium, of which extensive genotypic information is available, to identify genetic variants that contribute to chemotherapeutic agent-induced cytotoxicity. Our model integrated genotype, gene expression and sensitivity of HapMap cell lines to drugs. Cell lines derived from 30 trios of European descent (CEU) and 30 trios of African descent (YRI) were utilized. Cell growth inhibition at increasing concentrations of etoposide for 72 h was determined using alamarBlue assay. Gene expression on 176 HapMap cell lines (87 CEU and 89 YRI) was determined using the Affymetrix GeneChip Human Exon 1.0ST Array. We evaluated associations between genotype and cytotoxicity, genotype and gene expression and correlated gene expression of the identified candidates with cytotoxicity. The analysis identified 63 genetic variants that contribute to etoposide-induced toxicity through their effect on gene expression. These include genes that may play a role in cancer (AGPAT2, IL1B and WNT5B) and genes not yet known to be associated with sensitivity to etoposide. This unbiased method can be used to elucidate genetic variants contributing to a wide range of cellular phenotypes induced by chemotherapeutic agents.
A genome-wide approach to identify genetic variants that contribute to etoposide-induced cytotoxicity.
Sex
View SamplesIn addition to the differences between populations in transcriptional and translational regulation of genes, alternative pre-mRNA splicing (AS) is also likely to play an important role in regulating gene expression and generating variation in mRNA and protein isoforms. Recently, the genetic contribution to transcript isoform variation has been reported in individuals of recent European descent. We report here results of an investigation of the differences in AS patterns between human populations. AS patterns in 176 HapMap lymphoblastoid cell lines derived from individuals of European and African ancestry were evaluated using the Affymetrix GeneChip Human Exon 1.0 ST Array. A variety of biological processes such as immune response and mRNA metabolic process were found to be enriched among the differentially spliced genes. The differentially spliced genes also include some involved in human diseases that have different prevalence or susceptibility between populations. The genetic contribution to the population differences in transcript isoform variation was then evaluated by a genome-wide association using the HapMap genotypic data on single nucleotide polymorphisms (SNPs). The results suggest that local and distant genetic variants account for a substantial fraction of the observed transcript isoform variation between human populations.
Identification of common genetic variants that account for transcript isoform variation between human populations.
Sex
View SamplesHost-influenza virus interplay at the transcript level has been extensively characterized in epithelial cells. Yet, there are no studies that simultaneously characterize human host and influenza A virus (IAV) genomes. We infected human bronchial epithelial BEAS-2B cells with two seasonal IAV/H3N2 strains, Brisbane/10/07 and Perth/16/09 (reference strains for past vaccine seasons) and the well-characterized laboratory strain Udorn/307/72. Strand-specific RNA-seq of the infected BEAS-2B cells allowed for simultaneous analysis of host and viral transcriptomes, in addition to pathogen genomes, to reveal changes in mRNA expression and alternative splicing (AS). In general, patterns of global and immune gene expression induced by the three IAVs were mostly shared. However, AS of host transcripts and small nuclear RNAs differed between the seasonal and laboratory strains. Analysis of viral transcriptomes showed deletions of the polymerase components (defective interfering (DI)-like RNAs) within the genome. Surprisingly, we found that the neuraminidase gene undergoes AS, and that the splicing event differs between seasonal and laboratory strains. Our findings reveal novel elements of the host-virus interaction and highlight the importance of RNA-seq in identifying molecular changes at the genome level that may contribute to shaping RNA-based innate immunity. Overall design: Examination of RNA from three different H3N2 viruses (and mock infection) at three timepoints with 3 biological replicates each.
Strand-Specific Dual RNA Sequencing of Bronchial Epithelial Cells Infected with Influenza A/H3N2 Viruses Reveals Splicing of Gene Segment 6 and Novel Host-Virus Interactions.
No sample metadata fields
View SamplesTo investigate maternal whole blood gene expression profiles associated with spontaneous preterm birth (SPTB, <37 weeks) in asymptomatic pregnant women.
Maternal Whole Blood Gene Expression at 18 and 28 Weeks of Gestation Associated with Spontaneous Preterm Birth in Asymptomatic Women.
Specimen part, Subject
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