During neurogenesis, expression of the basic Helix-Loop-Helix NeuroD6/Nex1/MATH-2 transcription factor parallels neuronal differentiation, while maintaining the differentiated state in the mature nervous system. To further dissect NeuroD6 differentiation properties, we previously generated a NeuroD6-overexpressing stable PC12 cell line, PC12-ND6, which displays a neuronal phenotype characterized by spontaneous neuritogenesis, accelerated NGF-induced differentiation, and increased regenerative capacity. Furthermore, we reported that NeuroD6 promotes long-term neuronal survival upon oxidative stress triggered by serum deprivation. In this study, we identified the NeuroD6-mediated transcriptional regulatory pathways linking neuronal differentiation to survival, by conducting a genome-wide microarray analysis using PC12-ND6 cells and serum deprivation as a stress paradigm. Through a series of filtering steps and a gene-ontology analysis, we found that NeuroD6 promotes distinct but overlapping gene networks, consistent with the differentiation, regeneration, and survival properties of PC12-ND6 cells. Using a gene set enrichment analysis, we provide the first evidence of a compelling link between NeuroD6 and a set of heat shock proteins in the absence of stress, which may be instrumental to confer stress tolerance to PC12-ND6 cells. Immunocytochemistry results showed that HSP27 and HSP70 interact with cytoskeletal elements, consistent with their roles in neuritogenesis and preserving cellular integrity. HSP70 also colocalizes with mitochondria located in the soma, growing neurites and growth cones of PC12-ND6 cells prior to and upon stress stimulus, consistent with its neuroprotective functions. Collectively, our findings support the notion that NeuroD6 links neuronal differentiation to survival via the network of molecular chaperones and endows the cells with increased stress tolerance.
NeuroD6 genomic signature bridging neuronal differentiation to survival via the molecular chaperone network.
Sex, Specimen part
View SamplesGlucocorticoids (GCs) are steroid hormones widely used as pharmaceutical interventions, which act mainly by regulating gene expression levels. A large fraction of patients (~30%), especially those of African descent, show a weak response to treatment. To interrogate the contribution of variable transcriptional response to inter-ethnic differences, we measured in vitro lymphocyte GC sensitivity (LGS) and transcriptome-wide response to GCs in peripheral blood mononuclear cells (PBMCs) from African-American and European-American healthy donors. We found that transcriptional response after 8hrs treatment was significantly correlated with variation in LGS within and between populations. We found that NFKB1, a gene previously found to predict LGS within populations, was more strongly downregulated in European-Americans on average. NFKB1 could not completely explain population differences, however, and we found an additional 177 genes with population differences in the average log2 fold change (FDR<0.05), most of which also showed a weaker transcriptional response in AfricanAmericans. These results suggest that inter-ethnic differences in GC sensitivity reflect variation in transcriptional response at many genes, including regulators with large effects (e.g. NFKB1) and numerous other genes with smaller effects.
Inter-ethnic differences in lymphocyte sensitivity to glucocorticoids reflect variation in transcriptional response.
Sex, Age, Specimen part, Treatment
View SamplesGlucocorticoids (GC) and 1,25-dihydroxyvitamin D3 (1,25(OH)2 D3) are steroid hormones with anti-inflammatory properties with enhanced effects when combined. We previously showed that transcriptional response to GCs was correlated with inter-individual and inter-ethnic cellular response. Here, we profiled cellular and transcriptional responses to 1,25(OH)2 D3 from the same donors. We studied cellular response to combined treatment with GCs and 1,25(OH)2 D3 in a subset of individuals least responsive to GCs. We found that combination treatment had significantly greater inhibition of proliferation than with either steroid hormone alone. Overlapping differentially expressed (DE) genes between the two hormones were enriched for adaptive and innate immune processes. Non-overlapping differentially expressed genes with 1,25(OH)2 D3 treatment were enriched for pathways involving the electron transport chain, while with GC treatment, non-overlapping genes were enriched for RNA-related processes. These results suggest that 1,25(OH)2 D3 enhances GC anti-inflammatory properties through a number of shared and non-shared transcriptionally-mediated pathways.
Comparison of cellular and transcriptional responses to 1,25-dihydroxyvitamin d3 and glucocorticoids in peripheral blood mononuclear cells.
Sex, Age, Specimen part, Treatment
View SamplesZnO nanoparticles can elicit a range of perturbed cell responses in vitro. Exposure to topically applied sunscreens containing ZnO particles may or may not elicit a biological effect in mice.
Dermal absorption and short-term biological impact in hairless mice from sunscreens containing zinc oxide nano- or larger particles.
Specimen part
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Identical gene regulation patterns of T3 and selective thyroid hormone receptor modulator GC-1.
Sex, Age, Specimen part, Cell line
View SamplesThe genetic changes underlying metastatic melanoma need to be deciphered to develop new and effective therapeutics. Previously, genome-wide microarray analyses of human melanoma identified two reciprocal gene expression programs, that included expression of mRNAs regulated by either transforming growth factor, beta 1 (TGFB1) pathways or microphthalmia-associated transcription factor (MITF)/SRY-box containing gene 10 (SOX10) pathways. We extend this knowledge to include gene expression analyses of 5 additional human melanoma lines, and show that these lines also fall into either TGFB1 or MITF/SOX10 gene expression groups.
Distinct microRNA expression signatures are associated with melanoma subtypes and are regulated by HIF1A.
Cell line
View SamplesBackground:
Natural variants of AtHKT1 enhance Na+ accumulation in two wild populations of Arabidopsis.
Specimen part
View SamplesWe wanted to understand at what level BTS acts, i.e. how upstream BTS acts and if BTS misregulation affets only a subset or multiple subsets of Fe regulated genes. We studied WT and bts-3 mutant roots.
BRUTUS and its paralogs, BTS LIKE1 and BTS LIKE2, encode important negative regulators of the iron deficiency response in Arabidopsis thaliana.
Specimen part
View SamplesSynthetic selective thyroid hormone (TH) receptor (TR) modulators (STRMs) exhibit beneficial effects on dyslipidemias in animals and humans and reduce obesity, fatty liver and insulin resistance in preclinical animal models. STRMs differ from native THs in preferential binding to the TR subtype versus TR, increased uptake into liver and reduced uptake into other tissues. However, selective modulators of other nuclear receptors (NRs) exhibit important gene-selective actions which have been attributed to differential effects on receptor conformation and dynamics and these effects can have profound influences in animals and humans. While there are suggestions that STRMs could exhibit such gene-specific actions, the extent to which these effects are actually observed in vivo has not been explored. Here, we show that saturating concentrations of the main active form of TH, triiodothyronine (T3), and the prototype STRM GC-1 induce identical gene-sets in livers of euthyroid and hypothyroid mice and a human cultured hepatoma cell line that only expresses TR, HepG2. We find one case in which GC-1 exhibits a modest gene-specific reduction in potency versus T3, at angiopoietin-like factor 4 (ANGPTL4) in HepG2. Investigation of the latter effect confirms that GC-1 acts through TR to directly induce this gene. However, this gene-selective GC-1 activity is not related to unusual T3 response element (TRE) sequence, unlike previously documented promoter-selective STRM actions. Together, our data suggest that T3 and GC-1 exhibit almost identical gene regulation properties and that gene-selective actions of GC-1 and similar STRMs will be subtle and rare.
Identical gene regulation patterns of T3 and selective thyroid hormone receptor modulator GC-1.
Specimen part, Cell line
View SamplesGlucocorticoids (GCs) are steroid hormones produced by the human body in response to environmental stressors. Despite their key role as physiological regulators and widely administered pharmaceuticals, little is known about the genetic basis of inter-individual and inter-ethnic variation in GC response. As GC action is mediated by the regulation of gene expression, we profiled transcript abundance and protein secretion in EBV-transformed B lymphocytes from a panel of 114 individuals, including those of both African and European ancestry. Combining these molecular traits with genome-wide genetic data, we found that genotype-treatment interactions at polymorphisms near genes affected GC-regulation of expression for 26 genes and of secretion for IL6. A novel statistical approach revealed that these interactions could be distinguished into distinct types, with some showing genotypic effects only in GC-treated samples and others showing genotypic effects only in control-treated samples, with differing phenotypic and molecular interpretations. The insights into the genetic basis of variation in GC response and the statistical tools for identifying gene-treatment interactions that we provide will aid future efforts to identify genetic predictors of response to this and other treatments.
Interactions between glucocorticoid treatment and cis-regulatory polymorphisms contribute to cellular response phenotypes.
Specimen part, Treatment
View Samples