Purpose: The ability to rationally manipulate the transcriptional states of cells would be of great use in medicine and bioengineering. We have developed a novel algorithm, NetSurgeon, which utilizes genome-wide gene regulatory networks to identify interventions that force a cell toward a desired expression state. Results: We used NetSurgeon to select transcription factor deletions aimed at improving ethanol production in S. cerevisiae cultures that are catabolizing xylose. We reasoned that interventions that move the transcriptional states of cells utilizing xylose toward the fermentative state typical of cells that are producing ethanol rapidly (while utilizing glucose) might improve xylose fermentation. Some of the interventions selected by NetSurgeon successfully promoted a fermentative transcriptional state in the absence of glucose, resulting in strains with a 2.7-fold increase in xylose import rates, a 4-fold improvement in xylose integration into central carbon metabolism, or a 1.3-fold increase in ethanol production rate. Conclusions: We conclude by presenting an integrated model of transcriptional regulation and metabolic flux that will enable future metabolic engineering efforts aimed at improving xylose fermentation to prioritize functional regulators of central carbon metabolism. Overall design: Mutant and wildtype S. cerevisiae cells were put into 48 hour aerobic batch fermentations of synthetic complete medium supplmented with 2% glucose and 5% xylose and culture samples were taken at 4 hours and 24 hours for transcriptional profiling performed by RNA-Seq analysis. In addition, wildtype S. cerevisiae cells were grown in various single carbon sources for 12 hours and culture samples were taken for transcriptional profiling performed by RNA-Seq analysis.
Model-based transcriptome engineering promotes a fermentative transcriptional state in yeast.
Subject
View SamplesPurpose: To compare the transcriptome profiles (RNA-seq) of cultured human epididymis cells and tissue from the caput, corpus and cauda regions of the human epididymis. Methods: Human epididymis tissue was obtained with Institutional Review Board approval from 3 patients (UC05, UC06, UC09, range: 22 - 36 years) undergoing inguinal radical orchiectomy for a clinical diagnosis of testicular cancer. None of the epididymides had extension of the testicular cancer. The three anatomical regions: caput, corpus and cauda, were separated and segments of each snap frozen. Adult human epididymis epithelial (HEE) cultures were also established from tissue. RNA was extracted from both tissue and cultured HEE cells and RNA-seq libraries prepared (TruSeq RNA Sample Preparation Kit v2, Low-Throughput protocol, Illumina). Libraries were sequenced on Illumina HiSeq2500 machines. Data were analyzed using TopHat and Cufflinks. Results: Libraries generated ~19-39 million reads per library from the cells (95-99% mapping to the human genome) and ~14-39 million reads from the tissue samples (84-99% mapped). Raw reads were aligned to the genome with Tophat and gene expression values were processed using Cufflinks as Fragments Per Kilobase per Million mapped fragments (FPKM). FPKM values were subject to principle component analysis, which revealed that though caput, corpus and cauda cell samples respectively from UC05, UC06 and UC09 clustered together. RNA-seq data from the 3 biological replicas (UC05, UC06 and UC09) of caput, corpus and cauda were pooled for further analysis. Cufflinks was used to determine differentially expressed genes (DEGs) between caput, corpus and cauda cells, combined from the 3 donors. The gene expression profiles of corpus and cauda are remarkably similar and both differ from the caput to a similar degree. We identified ~40 genes differentially expressed between corpus and cauda and more than 1600 DEGs between caput and cauda. The DEGs for each comparison (caput and corpus/cauda) were analysed using a gene ontology process enrichment analysis (DAVID, Huang et al., NAR 2009;37:1-13, Huang et al., 2009 Nat Prot 4:44-57). Conclusions: Here we describe an in depth analysis of the gene expression repertoire of primary cultures of epithelial cells and intact tissues from each region of the adult human epididymis. These data will be valuable to decipher pathways of normal epididymis function and aspects of epididymis disease that cause male infertility. Overall design: RNA-seq was performed on libraries generated from caput, corpus and cauda-derived cultured cells (passage 2 or 3) from 3 donors and on caput, corpus and cauda tissue from 2 of the same donors. Donor age range: 22 - 36 years.
Expression profiles of human epididymis epithelial cells reveal the functional diversity of caput, corpus and cauda regions.
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View SamplesWe hypothesized that broad-scale expression profiling would provide insight into the regulatory pathways that control gene expression in response to stress, and potentially identify novel heat-responsive genes. HEp2 cells were heated at 37 to 43 C for 60 min to gauge the heat shock response, using as a proxy inducible HSP-70 quantified by western blot analysis. Based on these results, microarray experiments were conducted at 37, 40, 41, 42 and 43C (3 replicates/temperature x 5 groups = 15 U95Aver2 GeneChips). Using linear modeling, we compared the sets of microarrays at 40, 41, 42 and 43C with the 37C baseline temperature and took the union of the genes exhibiting differential gene expression signal to create two sets of heat shock response genes, each set reflecting either increased or decreased RNA abundance. Leveraging human and mouse orthologous alignments, we used the two lists of co-expressed genes to predict transcription factor binding sites in silico, including those for heat shock factor 1 (HSF1) and heat shock factor 2 (HSF2) transcription factors. We discovered HSF1 and HSF2 binding sites in 15 genes not previously associated with the heat shock response. We conclude that microarray experiments coupled with upstream promoter analysis can be used to identify novel genes that respond to heat shock. Additional experiments are required to validate these putative heat shock proteins and facilitate a deeper understanding of the mechanisms involved during the stress response.
Transcriptional profiles of human epithelial cells in response to heat: computational evidence for novel heat shock proteins.
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View SamplesMYB-bHLH-TTG1 regulates Arabidopsis seed coat biosynthesis pathways directly and indirectly via multiple tiers of transcription factors
MYB-bHLH-TTG1 Regulates Arabidopsis Seed Coat Biosynthesis Pathways Directly and Indirectly via Multiple Tiers of Transcription Factors.
Specimen part
View SamplesHNF1a and HNF1ß recognize the same DNA consensus sequence in the genome, to which they bind as homodimers or heterodimers. Both factors share a high degree of homology their DNA binding and dimerization (N-terminus) regions but have a more divergent C-terminal transactivation domain. HNF1ß is essential for the generation of a functional male reproductive tract in mice and genital tract abnormalities are evident in humans with recessive mutations in HNF1ß. The functions of HNF1a and HNF1ß have been studied in epithelia from other several tissues (liver, kidney, intestine, and pancreas) but their role in the adult human epididymis epithelium (HEE) remains unexplored. We established that HNF1a/ß are expressed in caput HEE cells and are predicted to occupy cis-regulatory elements in these cells. To investigate the contribution of HNF1 in controlling gene expression in caput cells we performed siRNA-mediated depletion of HNF1a and HNF1ß together, followed by RNA-seq analysis. Three replicas of caput cells were transfected with the specific siRNAs or with a non-targeting control siRNA. RNA-seq after HNF1 depletion showed significant alterations in the expression of genes encoding ion channels and exchangers that are involved in controlling the luminal environment in the caput epididymis. Overall design: mRNA profiles from Caput HEE cells transfected with negative control (NC) or HNF1alpha and HNF1beta siRNA, in triplicate.
HNF1 regulates critical processes in the human epididymis epithelium.
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View SamplesThree groups of male +b and bb rats were obtained (ages between 6 and 14 months) and intestinal scrapes were taken. Tissues was combined from 3 rats per group and processed for gene chip analysis.
Induction of arachidonate 12-lipoxygenase (Alox15) in intestine of iron-deficient rats correlates with the production of biologically active lipid mediators.
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View SamplesThe epithelium lining the epididymis in the male reproductive tract maintains a luminal environment that promotes sperm cell maturation. This process is dependent on the coordinated expression of many genes that encode proteins with a role in epithelial transport. We previously generated genome-wide maps of open chromatin in primary human fetal epididymis epithelial cells to identify potential regulatory elements controlling coordinated gene expression in the epididymis epithelium. Subsequent in silico analysis identified transcription factor binding sites (TFBS) that were over-represented in the HEE open chromatin, include the motif for paired box 2 (PAX2). PAX2 is a critical transcriptional regulator of urogenital tract development, which is well studied in the kidney but is unexplored in the epididymis. Due to the limited lifespan of primary HEE cells in culture we investigated the role of PAX2 in an immortalized HEE cell line (REP). First, REP cells were evaluated by DNase-seq and their open chromatin map overlapped that of primary HEE cells at ~ 65% of sites. Moreover, the PAX2-binding motif was again identified as an overrepresented TFBS within intergenic open chromatin, though on fewer chromosomes than in the primary HEE cells. To identify PAX2-target genes in REP cells, RNA-seq analysis was performed after siRNA-mediated depletion of PAX2 in comparison to a non-targeting siRNA. In response to PAX2-represssion, 3142 transcripts were differentially expressed (1334 up-regulated and 1808 down-regulated). Novel PAX2 targets included multiple genes encoding proteins with a predicted function in the epididymis epithelium. Overall design: mRNA profile of control and PAX2 knockdown REP cells
Open chromatin mapping identifies transcriptional networks regulating human epididymis epithelial function.
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View SamplesWhen using cell lines to study cancer, phenotypic similarity to the original tumor is paramount. Yet, little has been done to characterize how closely Merkel cell carcinoma (MCC) cell lines model native tumors. To determine their similarity to MCC tumor samples, we characterized MCC cell lines via gene expression microarrays. Using whole transcriptome gene expression signatures and a computational bioinformatic approach, we identified significant differences between variant cell lines (UISO, MCC13, and MCC26) and fresh frozen MCC tumors. Conversely, the classic WaGa and Mkl-1 cell lines more closely represented the global transcriptome of MCC tumors. When compared to publicly available cancer lines, WaGa and Mkl-1 cells were similar to other neuroendocrine tumors, but the variant cell lines were not. WaGa and Mkl-1 cells grown as xenografts in mice had histological and immunophenotypical features consistent with MCC, while UISO xenograft tumors were atypical for MCC. Spectral karyotyping and short tandem repeat analysis of the UISO cells matched the original cell line's description, ruling out contamination. Our results validate the use of transcriptome analysis to assess the cancer cell line representativeness and indicate that UISO, MCC13, and MCC26 cell lines are not representative of MCC tumors, whereas WaGa and Mkl-1 more closely model MCC.
Assessment of cancer cell line representativeness using microarrays for Merkel cell carcinoma.
Specimen part, Disease, Cell line
View SamplesMycobacterium abscessus is an emerging pathogen causing pulmonary infections in those with inflammatory lung disorders, such as Cystic Fibrosis (CF), and is associated with the highest fatality rate among rapidly growing mycobacteria (RGM). Phenotypically, MAB manifests as either a Smooth (MAB-S) or a Rough (MAB-R) morphotype, which differ in their levels of cell wall glycopeptidolipids (GPLs) and in their pathogenicity in vivo. As one of the primary immune cells encountered by MAB, we sought to examine the early transcriptional events within macrophages, following infection with both MAB-S or MAB-R. We sampled the small RNA (sRNA) transcriptome of THP-1-derived macrophages infected with both MAB-R and MAB-S at 1, 4 and 24 hours post-infection (hpi) using RNA-seq. MAB-S elicited a more robust transcriptional response at the miRNA level, reflecting higher cytokine levels in culture supernatants. However, and a direct comparison identified no differentially expressed miRNAs between MAB-R- and MAB-S-infected cells. Most of the induced miRNAs have previously been associated with mycobacterial infection and overall miRNA expression patterns were similarly highly correlated between the morphotypes. Overall design: THP-1-derived macrophages were infected in parallel with the MAB-R and MAB-S morphotypes. Poly-A selected RNAs were purified and sequenced at 1, 4 and 24 hours post-infection, and compared with uninfected controls.
High-throughput transcriptomics reveals common and strain-specific responses of human macrophages to infection with Mycobacterium abscessus Smooth and Rough variants.
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View SamplesExpression of the proendocrine gene neurogenin 3 (Ngn3) is required for the development of pancreatic islets. In order to better characterize the molecular events regulated by Ngn3 during development, we have determined the expression profile of differentiating murine embryonic stem cells (mESCs) uniformly induced to overexpress Ngn3. An ESC line was created that allows for the induction of Ngn3 by adding doxycycline (Dox) to the culture medium. Genome-wide microarray analysis was performed to identify genes regulated by Ngn3 in a variety of both undifferentiated and differentiated conditions. Characterization of pancreatic developmental markers during embryoid body (EB) formation revealed an optimum context for Ngn3 induction. Neuroendocrine genes including neurogenic differentiation 1 (NeuroD1) and single minded 1 (Sim1) were found to be significantly upregulated. Genes regulated by Ngn3 independent of the context were analyzed using systematic gene ontology tools and revealed Notch signaling as the most significantly regulated signaling pathway (p=0.009). This result is consistent with the hypothesis that Ngn3 expression makes the cell competent for Notch signaling to be activated and conversely, more sensitive to Notch signaling inhibition. Indeed, EBs induced to express Ngn3 were significantly more sensitive to gamma-secretase inhibitor-mediated Notch signaling inhibition (p<0.0001). Moreover, we find that Ngn3 induction in differentiating ESCs results in significant increases in insulin, glucagon, and somatostatin transcription.
Differentiation of embryonic stem cells conditionally expressing neurogenin 3.
No sample metadata fields
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