C2C12 cells are mouse skeletal muscle cells. These cells were transfected with shRNA against FoxO1, FoxO3, and FoxO4. FoxO1, FoxO3, and FoxO4 are the known paralogues expressed in this cell line.
Codependent activators direct myoblast-specific MyoD transcription.
No sample metadata fields
View SamplesMicroRNAs (miRNAs) are short noncoding RNA molecules regulating the expression of mRNAs. Target identification of miRNAs is computationally difficult due to the relatively low homology between miRNAs and their targets. We present here an experimental approach to target identification where the cartilage-specific miR-140 was overexpressed and silenced in cells it is normally expressed in separate experiments. Expression of mRNAs was profiled in both experiments and the intersection of mRNAs repressed by miR-140 overexpression and derepressed by silencing of miR-140 was identified. The intersection contained only 49 genes, although both treatments affected the accumulation of hundreds of mRNAs. These 49 genes showed a very strong enrichment for the miR-140 seed sequence implying that the approach is efficient and specific. 21 of these 49 genes were predicted to be direct targets based on the presence of the seed sequence. Interestingly, none of these were predicted by the published target prediction methods we used. One of the potential target mRNAs, Cxcl12, was experimentally validated by Northern blot analysis and a luciferase reporter assay.
Experimental identification of microRNA-140 targets by silencing and overexpressing miR-140.
No sample metadata fields
View SamplesMicroRNAs have emerged as major genetic elements in the genesis and suppression of cancer. Here, multi-dimensional cancer genome analysis and validation has defined a novel Glioblastoma Multiforme (GBM) tumor suppressor pathway and mechanism of action centered on Quaking (QK), a member of the STAR family of RNA-binding proteins. Combined functional, biochemical and computational studies establish that p53 directly regulates QK gene expression, QK protein binds and stabilizes miR-20a of the cancer-relevant miR-17-92 cluster, and miR-20a in turn functions to regulate TGFR2 and the TGF signaling network. Linkage of these pathway components is supported by their genome and expression status across GBM specimens and by their gain- and loss-of-function interactions in in vitro and in vivo complementation studies. This p53-QK-miR-20a axis expands our understanding of the p53 tumor suppression network in cancer and reveals a novel tumor suppression mechanism involving regulation of specific cancer-relevant microRNAs.
STAR RNA-binding protein Quaking suppresses cancer via stabilization of specific miRNA.
Specimen part, Cell line
View SamplesActivated phosphoinositide 3-kinase (PI3K)-AKT signaling appears to be an obligate event in the development of cancer. The highly related members of the mammalian FoxO transcription factor family, FoxO1, FoxO3, and FoxO4, represent one of several effector arms of PI3K-AKT signaling, prompting genetic analysis of the role of FoxOs in the neoplastic phenotypes linked to PI3K-AKT activation. While germline or somatic deletion of up to five FoxO alleles produced remarkably modest neoplastic phenotypes, broad somatic deletion of all FoxOs engendered a progressive cancer-prone condition characterized by thymic lymphomas and hemangiomas, demonstrating that the mammalian FoxOs are indeed bona fide tumor suppressors. Transcriptome and promoter analyses of differentially affected endothelium identified direct FoxO targets and revealed that FoxO regulation of these targets in vivo is highly context-specific, even in the same cell type. Functional studies validated Sprouty2 and PBX1, among others, as FoxO-regulated mediators of endothelial cell morphogenesis and vascular homeostasis.
FoxOs are lineage-restricted redundant tumor suppressors and regulate endothelial cell homeostasis.
Specimen part
View SamplesIdentify potential QK-regulated mRNAs and linked pathways by comparing the transcriptional profiles of shGFP- and shQK-transduced Ink4a/Arf-/- Pten-/- primary mouse astrocytes
STAR RNA-binding protein Quaking suppresses cancer via stabilization of specific miRNA.
No sample metadata fields
View SamplesIdentify potential miR-20a regulated mRNAs and linked pathways in the setting of QK knockdown by comparing the transcriptional profiles of shQK-transduced primary mouse Ink4a/Arf-/- Pten-/- astrocytes together with miR-20a or a scrambled miRNA control (miR-NT)
STAR RNA-binding protein Quaking suppresses cancer via stabilization of specific miRNA.
No sample metadata fields
View SamplesFoxOs cooperatively regulate diverse pathways governing neural stem cell homeostasis
FoxOs cooperatively regulate diverse pathways governing neural stem cell homeostasis.
Cell line
View SamplesHigh-fat diets are associated with increased obesity and metabolic disease in mice and humans. Here we used analysis of variance (ANOVA) to scrutinize a microarray data set consisting of 10 inbred strains of mice from both sexes fed atherogenic high-fat and control chow diets. An overall F-test was applied to the 40 unique groups of strain-diet-sex to identify 15,288 genes with altered transcription. Bootstrapping k-means clustering separated these changes into four strain-dependent expression patterns, including two sex-related profiles and two diet-related profiles. Sex-induced effects correspond to secretion (males) or fat and energy metabolism (females), whereas diet-induced changes relate to neurological processes (chow) or immune response (high-fat). The full set of pairwise contrasts for differences between strains within sex (90 different statistical tests) uncovered 32,379 total changes. These differences were unevenly distributed across strains and between sexes, indicating that strain-specific responses to high-fat diet differ between sexes. Correlations between expression levels and 8 obesity-related traits identified 5,274 associations between transcript abundance and measured phenotypic endpoints. From this number, 2,678 genes are positively correlated with total cholesterol levels and associate with immune-related categories while 2,596 genes are negatively correlated with cholesterol and connect to cholesterol synthesis.
Practical applications of the bioinformatics toolbox for narrowing quantitative trait loci.
Sex
View SamplesAlmost all human pancreatic ductal adenocarcinomas (PDACs) are driven by oncogenic Kras and the progression of the disease is characterized by the serial appearance of certain genetic lesions. Mouse models have convincingly shown that Kras mutation induces classical PanIN lesions that can progress to PDAC in the appropriate tumor suppressor background. However, the cooperative mechanism between mutant Kras-dependent signaling surrogates and other oncogenic pathways remains to be fully elucidated in order to devise better therapeutic strategy. Mounting evidence PTEN/PI3K perturbation on PDAC tumorigenesis, we observed frequent PTEN inactivation at both genomic and histopathological levels in primary human PDAC samples. The importance of PTEN/PI3K pathway during the development of PDAC was further supported by genetic studies demonstrating that Pten deficiency in cooperation with Kras activation accelerated the formation of invasive PDAC. Mechanistically, combined Kras mutation and Pten inactivation leads to NFkB activation and subsequent induction of cytokine pathways, accompanied with strong stromal activation and immune cell infiltration. Therefore, PTEN/PI3K pathway dictates the activity of NFkB network and serves as a major surrogate during Kras-mediated pancreatic tumorigenesis.
PTEN is a major tumor suppressor in pancreatic ductal adenocarcinoma and regulates an NF-κB-cytokine network.
Specimen part
View SamplesThe maintenance of advanced malignancies relies on continued activity of driver oncogenes, although their rate-limiting role is highly context-dependent with respect to tumor types and associated genetic alterations. Oncogenic Kras mutation is the signature event in human pancreatic ductal adenocarcinoma (PDAC), serving a critical role in tumor initiation. Here, an inducible KrasG12D-driven p53 mutant PDAC mouse model establishes that advanced PDAC remains strictly dependent on continued KrasG12D expression and that KrasG12D serves a vital role in the control of tumor metabolism, through stimulation of glucose uptake and channeling of glucose intermediates through the hexosamine biosynthesis pathway (HBP) and the pentose phosphate pathway (PPP). Notably, these studies reveal that oncogenic Kras regulates ribose biogenesis. Unlike canonical models of PPP-mediated ribose biogenesis, we demonstrate that oncogenic Kras drives intermediates from enhanced glycolytic flux into the non-oxidative arm of the PPP, thereby decoupling ribose biogenesis from NADPNADPH-mediated redox control. Together, this work provides in vivo mechanistic insights into how oncogenic Kras promotes metabolic reprogramming in native tumors and illuminates potential metabolic targets that can be exploited for therapeutic benefit in Kras-driven PDAC.
Oncogenic Kras maintains pancreatic tumors through regulation of anabolic glucose metabolism.
Specimen part, Treatment
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