Diamond-Blackfan anemia (DBA) is a rare bone marrow failure disorder that affects 7 out of 1,000,000 live births and has been associated with mutations in components of the ribosome. In order to characterize the genetic landscape of this heterogeneous disorder, we recruited a cohort of 472 individuals with a clinical diagnosis of DBA and performed whole exome sequencing (WES). We identified rare and predicted damaging mutations in likely causal genes for 78% of individuals. The majority of mutations were singletons, absent from population databases, predicted to cause loss of function, and in one of 19 previously reported ribosomal protein (RP) encoding genes. Using exon coverage estimates, we identified and validated 31 deletions in RP genes. We also observed an enrichment for extended splice site mutations and validated their diverse effects using RNA sequencing in individual-derived cell lines. Leveraging the size of our cohort, we observed robust genotype-phenotype associations with congenital abnormalities and treatment outcomes. We further identified rare mutations in 7 previously unreported RP genes that may cause DBA, as well as several distinct disorders that appear to phenocopy DBA, including 9 individuals with biallelic CECR1 mutations that result in deficiency of ADA2. However, no new genes were identified at exome-wide significance, suggesting that there are no unidentified genes containing mutations readily identified by WES that explain > 5% of DBA cases. Overall, this report should not only inform clinical practice for DBA individuals, but also the design and analysis of rare variant studies for heterogeneous Mendelian disorders. Overall design: 9 individuals with DBA with putative splice mutations and 5 control individuals were processed for RNA-seq.
The Genetic Landscape of Diamond-Blackfan Anemia.
Specimen part, Disease, Subject
View SamplesHuman blood monocytes were differentiated over six days with either 100 ng/ml M-CSF or 1 umol/l CXCL4
CXC chemokine ligand 4 induces a unique transcriptome in monocyte-derived macrophages.
Specimen part
View SamplesFoam cell formation from monocyte-derived macrophages is a hallmark of atheroscle-rotic lesions. Aspects of this process can be recapitulated in vitro by exposing MCSF-induced or platelet factor4 (CXCL4)-induced macrophages to oxidized (ox) or minimally modified (mm) low density lipoprotein (LDL). We measured gene expression in periph-eral blood mononuclear cells (PBMCs), monocytes and macrophages treated with CXCL1 (GRO-) or CCL2 (MCP-1) as well as foam cells induced by native LDL, mmLDL or oxLDL using 22 Affymetrix gene chips. Using an advanced Bayesian error-pooling approach and a heterogeneous error model (HEM) with a false discovery rate (FDR) <0.05, we found 5,303 of 22,215 probe sets to be significantly regulated in at least one of the conditions. Among a subset of 917 candidate genes that were preselected for their known biological functions in macrophage foamcell differentiation, we found that 290 genes met the above statistical criteria for significant differential expression patterns. While many expected genes were found to be upregulated by LDL and oxLDL, very few were induced by mmLDL. We also found induction of unexpected genes, most strikingly MHC-II and other dendritic cell markers such as CD11c. The gene expression patterns in response to oxLDL were similar in MCSF-induced and CXCL4-induced macrophages. Our findings suggest that LDL and oxLDL, but not mmLDL, induce a dendritic cell-like phenotype in macrophages, suggesting that these cells may be able to present antigens and support an immune response.
Induction of dendritic cell-like phenotype in macrophages during foam cell formation.
No sample metadata fields
View SamplesNatural killer (NKT) T cells exhibit tissue distribution, surface phenotype, and functional responses that are strikingly different from those of conventional T cells. The transcription factor PLZF is responsible for most of these properties, as its ectopic expression in conventional T cells is sufficient to confer to them an NKT-like phenotype. The molecular program downstream of PLZF, however, is largely unexplored.
PLZF Controls the Expression of a Limited Number of Genes Essential for NKT Cell Function.
Sex, Specimen part
View SamplesThe response of cells to hypoxia is characterised by co-ordinated regulation of many genes. Studies of the regulation of the expression of many of these genes by oxygen has implicated a role for the heterodimeric transcription factor hypoxia inducible factor (HIF). The mechanism of oxygen sensing which controls this heterodimeric factor is via oxygen dependent prolyl and asparaginyl hydroxylation by specific 2-oxoglutarate dependent dioxygenases (PHD1, PHD2, PHD3 and FIH-1). Whilst HIF appears to have a major role in hypoxic regulation of gene expression, it is unclear to what extent other transcriptional mechanisms are also involved in the response to hypoxia. The extent to which 2-oxoglutarate dependent dioxygenases are responsible for the oxygen sensing mechanism in HIF-independent hypoxic gene regulation is also unclear. Both the prolyl and asparaginyl hydroxylases can be inhibited by dimethyloxalylglycine (DMOG). Such inhibition can produce activation of the HIF system with enhanced transcription of target genes and might have a role in the therapy of ischaemic disease. We have examined the extent to which the HIF system contributes to the regulation of gene expression by hypoxia, to what extent 2-oxoglutarate dependent dioxygenase inhibitor can mimic the hypoxic response and the nature of the global transcriptional response to hypoxia. We have utilised microarray assays of mRNA abundance to examine the gene expression changes in response to hypoxia and to DMOG. We demonstrate a large number of hypoxically regulated genes, both known and novel, and find a surprisingly high level of mimicry of the hypoxic response by use of the 2-oxoglutarate dependent dioxygenase inhibitor, dimethyloxalylglycine. We have also used microarray analysis of cells treated with small interfering RNA (siRNA) targeting HIF-1alpha and HIF-2alpha to demonstrate the differing contributions of each transcription factor to the transcriptional response to hypoxia. Candidate transcripts were confirmed using an independent microarray platform and real-time PCR. The results emphasise the critical role of the HIF system in the hypoxic response, whilst indicating the dominance of HIF-1alpha and defining genes that only respond to HIF-2alpha.
Concordant regulation of gene expression by hypoxia and 2-oxoglutarate-dependent dioxygenase inhibition: the role of HIF-1alpha, HIF-2alpha, and other pathways.
No sample metadata fields
View SamplesThe aim of the study is to evaluate oxygen regulated gene expression in human peripheral blood lymphocytes using microarray analysis.
Variations within oxygen-regulated gene expression in humans.
No sample metadata fields
View SamplesPRC, a member of the PGC-1 coactivator family, is responsive to serum growth factors and up regulated in proliferating cells. Here, we investigated its in vivo role by stably silencing PRC expression with two different short hairpin RNAs (shRNA#1 and shRNA#4) that were lentivirally introduced into U2OS cells. ShRNA#1 transductants exhibited nearly complete knockdown of PRC protein whereas shRNA#4 transductants expressed PRC protein at approximately 15 percent of the control level. Complete PRC silencing by shRNA#1 resulted in a severe inhibition of respiratory growth, reduced expression of respiratory protein subunits from complexes I, II, III and IV, markedly lower complex I and IV respiratory enzyme levels and diminished mitochondrial ATP production. Surprisingly, shRNA#1 transductants exhibited a striking proliferation of abnormal mitochondria that were devoid of organized cristae and displayed severe membrane abnormalities. Although shRNA#4 transductants had normal respiratory subunit expression and a moderately diminished respiratory growth rate, both transductants showed markedly reduced growth on glucose accompanied by inhibition of G1/S cell cycle progression. Microarray analysis revealed striking overlaps in the genes affected by PRC silencing in the two transductants and the functional identities of these overlapping genes were consistent with the observed mitochondrial and cell growth phenotypes. The consistency between phenotype and PRC expression levels in the two independent transductant lines argues that the defects result from PRC silencing and not from off target effects. These results support a role for PRC in the integration of pathways directing mitochondrial respiratory function and cell growth.
Short hairpin RNA-mediated silencing of PRC (PGC-1-related coactivator) results in a severe respiratory chain deficiency associated with the proliferation of aberrant mitochondria.
No sample metadata fields
View SamplesDicamba is an auxin-like herbicide that can stimulate the production of ethylene and ABA biosynthesis. The subsequent stomatal closure and build-up of reactive oxygen species is hypothesized to contribute to plant death.
Mutant analysis in Arabidopsis provides insight into the molecular mode of action of the auxinic herbicide dicamba.
Specimen part
View SamplesThe study was designed in order to identify genes differentially expressed when glucocorticoid signaling is blocked by a glucocorticoid-receptor antagonist (RU486 mifepristone) in the context of brain inflammation induced by bacterial lipopolysaccharide (LPS). LPS is only able to cause murine brain damage in our experimental conditions upon RU486 pre-treatment. Hence, the study may reveal potential candidate genes to mediate neuroprotection or neurotoxicity. Due to the factorial design of the experiment, RU486 main-effect could be dissociated from the effects resultant of RU486/inflammation interaction. In addition, brain dissection was conducted to verify the effects in the brain side ipsilateral or contralateral to the site of intracerebral LPS infusion.
Genes involved in the balance between neuronal survival and death during inflammation.
Sex, Age, Specimen part
View SamplesCritically ill preterm infants experience multiple stressors while hospitalized. Morphine is commonly prescribed to ameliorate their pain and stress. We hypothesized that neonatal stress will have a dose-dependent effect on hippocampal gene expression, and these effects will be altered by morphine treatment. Male C57BL/6 mice were exposed to 5 treatment conditions between postnatal day 5 and 9: 1) Control, 2) mild stress + saline, 3) mild stress + morphine, 4) severe stress + saline and 5) severe stress + morphine. Hippocampal RNA was extracted and analyzed using Affymetrix Mouse Gene 1.0 ST Arrays. Single gene analysis and gene set analysis were used to compare groups with validation by qPCR. Stress resulted in enrichment of genes sets related to fear response, oxygen carrying capacity and NMDA receptor synthesis. Morphine downregulated gene sets related to immune function. Stress plus morphine resulted in enrichment of mitochondrial electron transport gene sets, and down-regulation of gene sets related to brain development and growth. We conclude that neonatal stress alone influences hippocampal gene expression, morphine alters a subset of stress-related changes in gene expression and influences other gene sets. Stress plus morphine show interaction effects not present with either stimulus alone. These changes may alter neurodevelopment.
Effects of neonatal stress and morphine on murine hippocampal gene expression.
Sex, Specimen part, Treatment
View Samples