We describe a novel quantitative cDNA expression profiling strategy, involving amplification of the majority of mouse transcriptome using a defined set of 44 heptamer primers. The amplification protocol allows for efficient amplification from as low as 50pg of mRNA and did not alter the expression of the transcripts even with 200 fold dilution of the minimum requirement of the starting material (10ng of mRNA) for standard RNA-seq protocols. We implemented our methodology on embryological lineage segregation, achieved by graded activation of Activin A/TGFß signaling in mouse embryonic stem cells (mESCs). The fold changes in transcript expression were in excellent agreement with quantitative RT-PCR and we observed a dynamic range spanning more than five orders of magnitude in RNA concentration with a reliable estimation of low abundant transcripts. Our transcriptome data identified key lineage markers, while the high sensitivity showed that novel lineage specific transcripts anticipate the differentiation of specific cell types. We compared our strategy with Std. RNA-seq (Mortazavi et al. 2008) and SMART-seq (Ramsköld et al. 2012). We also showed potential of our methodology to suppress the representation of highly expressing ribosomal transcripts. Overall design: Sequencing was performed on day 4 differentiating mouse ESCs treated for two days with 3 different dosages of Activin A (3ng/mL, 15ng/mL and 100ng/mL). The cells were also treated with SB-431542. Serial dilutions of mRNA derived Activin A(3ng/mL) samples were used to detemine the minimum amount of mRNA required to construct relaible sequencing library. SMARTseq libraries were prepared for both Activin A(3ng/mL) and Activin A(100ng/mL) samples. Three Different primer sets were designed to suppress the representaiton of Ribosomal transcripts.
Quantitative transcriptomics using designed primer-based amplification.
Specimen part, Treatment
View SamplesTranscriptomics data obtained from limiting amounts of mRNA is often noisy, providing primarily qualitative changes in transcript expressions. So far, technical variations arising out of the library preparation protocols have not been adequately characterized at reduced levels of mRNA. Here, we generated sequencing libraries from limiting amounts of mRNA using three amplification-based methods, viz. Smart-seq, DP-seq and CEL-seq, and demonstrated significant technical variations in these libraries. Reduction in mRNA levels led to inefficient amplification of the majority of low to moderately expressed transcripts. Furthermore, stochasticity in primer hybridization and/or enzyme incorporation was magnified during the amplification step resulting in significant distortions in fold changes of the transcripts. Consequently, the majority of the differentially expressed transcripts identified were either high-expressed and/or exhibited high fold changes. High technical variations, which were sequencing depth independent, ultimately masked subtle biological differences mandating the development of improved amplification-based strategies for quantitative transcriptomics from limiting amounts of mRNA. Overall design: Sequencing libraries were prepared from serial dilutions of mRNA, ranging from 1 ng to 25 pg, using three amplification-based methods, viz. Smart-seq, DP-seq and CEL-seq. The mRNA was derived from an in vitro model of lineage segregation achieved by modulating TGF beta signaling pathway in differentiating mouse embryonic stem cells.
Technical variations in low-input RNA-seq methodologies.
Specimen part, Subject
View SamplesOver one million prostate biopsies are performed in the U.S. every year. However, pathology examination is not definitive in a significant percentage of cases due limited diagnostic tumor. We have observed that the microenvironment of prostate tumor cells exhibits numerous differential gene expression changes and have asked whether such information can be used to distinguish tumor from nontumor. We initially compared expression analysis data (Affymetrix U133plus2) from 18 volunteer biopsy specimens to 17 specimens containing largely tumor-adjacent stroma and identified 964 significant (p_adj < 0.01 and B > 0) expression changes. These genes were filtered to eliminate possible aging-related genes and genes expressed in tumor cells > 10% of the stroma cell expression level leading to 23 candidate genes (28 Affymetrix probe sets). A classifier based on the 28 probe sets was tested on 289 independent cases, including 195 tumor-bearing cases, 99 nontumor cases (normal biopsies, normal autopsies, remote stroma as well as pure tumor adjacent stroma) all with accuracies >85%, sensitivities >90% and specificities >85%. These results indicate that the prostate cancer microenvironment exhibits reproducible changes useful for categorization as tumor and nontumor.
In silico estimates of tissue components in surgical samples based on expression profiling data.
Subject
View SamplesProstate cancer gene expression profiles were studied in this project. A total RNA from 148 prostate sample with various amount of different cell types were hybridized to Affymetrix U133A arrays. The percentage of different cell types vary considerably among samples and were determined by pathologist. Cell type specific genes can be determined by linear regression using the methods of Stuart et al, PNAS, 2004.
In silico estimates of tissue components in surgical samples based on expression profiling data.
No sample metadata fields
View SamplesSeveral of the essential core transcriptional control elements in human embryonic stem cells (ESCs) have been identified, but the production and function of alternative isoforms in self-renewal, pluripotency and tissue lineage specification remain largely unknown.
Alternative splicing in the differentiation of human embryonic stem cells into cardiac precursors.
No sample metadata fields
View SamplesPrevious studies have revealed that UV-stimulation of a variety of cells leads to activation of the EGF receptor, induction of Egr1, growth inhibition and apoptosis. On the other hand both Egr1 and EGF receptor activation are implicated in promoting the progression of prostate cancer. We treated M12 tumorigenic prostate epithelial cells which express little Egr1 with UV irradiation which rapidly activated the EGF receptor and elevated Egr1. Treatment with specific EGFR and ERKI/II inhibitors (PD153035 and UO126, respectively) confirmed that the upregulation of Egr1 was downstream of EGFR and ERKI/II Map kinase pathway. ChIP on chip experiments using Egr1 antibody identified 288 significantly bound promoters upon UV stimulation. Of these target genes, 40% had consensus Egr1 site in their promoters, considerably greater than that expected by chance (p < 0.005). The array binding results were validated by PCR analysis of 25 genes using DNA from conventional IP experiment. Affymetrix gene expression analysis of UV treated and control cells confirmed that a significant number of these bound promoters showed gene expression changes. Addition of siRNA to Egr1 confirmed that the gene expression changes were dependent upon Egr1 expression. Addition of EGF led to similar expression changes for nine tested genes. Proliferation and apoptosis assays confirmed that M12 cells undergo growth arrest and apoptosis following UV irradiation. Moreover, addition of EGF also promoted significant growth inhibition. These results indicate the M12 cells undergo a EGF receptor dependent apoptosis response upon UV-stimulation and that Egr1 mediates the regulation of numerous genes downstream of the EGF receptor that are associated with this response.
Egr1 regulates the coordinated expression of numerous EGF receptor target genes as identified by ChIP-on-chip.
No sample metadata fields
View SamplesEGR3 expression is upregulated in human prostate cancer compared to normal prostate tissue and is associated with absence of relapse, while low EGR3 expression in tumors is predicitive of disease relapse (Pio et al., PLOS One 2013; 8(1):e54096). However the function of EGR3 in prostate cancer is unknown. Human prostate cancer cells M12 containing high levels of EGR3 were used for shRNA-mediated silencing of EGR3. Gene expression analysis of EGR3 knockdown cells reveals a role in inflammation and the existence of a crosstalk with the NFkB pathway.
Early growth response 3 (Egr3) is highly over-expressed in non-relapsing prostate cancer but not in relapsing prostate cancer.
Cell line, Treatment
View SamplesHuman prostate cancer tissues analyses
In silico dissection of cell-type-associated patterns of gene expression in prostate cancer.
No sample metadata fields
View SamplesThe Gata4 transcription factor is essential for normal heart development, but the molecular basis for its function remain poorly understood. We profiled at the whole genome level transcript changes in cardiomyocytes when Gata4 is depleted from zebrafish embryos. Our objective was to elucidate the cardiomyocyte-specific molecular program functioning downstream of Gata4 in order to better understand the role of Gata4 in cardiac morphogenesis. Overall design: Six samples in total are deposited. Three replicate control samples and three replicate Gata4 morphant samples were analyzed.
Small heat shock proteins Hspb7 and Hspb12 regulate early steps of cardiac morphogenesis.
No sample metadata fields
View SamplesThis SuperSeries is composed of the SubSeries listed below.
High-throughput screening of tyrosine kinase inhibitor cardiotoxicity with human induced pluripotent stem cells.
Specimen part, Cell line, Treatment, Subject
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