The Wnt signaling pathway is deregulated in over 90% of human colorectal cancers. Catenin, the central signal transducer of the Wnt pathway, can directly modulate gene expression by interacting with transcription factors of the TCF/LEF-family. In the present study we investigate the role of Wnt signaling in the homeostasis of intestinal epithelium using tissue-specific, inducible beta-catenin gene ablation in adult mice. Block of Wnt/beta-catenin signaling resulted in rapid loss of transient-amplifying cells and crypt structures. Importantly, intestinal stem cells were induced to terminally differentiate upon deletion of beta-catenin resulting in a complete block of intestinal homeostasis and fatal loss of intestinal function. Transcriptional profiling of mutant crypt mRNA isolated by laser capture micro dissection confirmed those observations and allowed to identify genes potentially responsible for the functional preservation of intestinal stem cells.
Wnt/beta-catenin is essential for intestinal homeostasis and maintenance of intestinal stem cells.
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View SamplesHere we identify HOXA5 as an important repressor of intestinal stem cell fate in vivo and identify a reciprocal feedback between HOXA5 and Wnt signaling. HOXA5 is suppressed by the Wnt pathway to maintain stemness and becomes active only outside the intestinal crypt where it inhibits Wnt signaling to enforce differentiation. In colon cancer, HOXA5 is down-regulated and its re-expression induces loss of the cancer stem cell phenotype preventing tumor progression and metastasis. Tumor regression by HOXA5 induction can be triggered by retinoids, which represents a tangible means to treat colon cancer by eliminating cancer stem cells.
HOXA5 Counteracts Stem Cell Traits by Inhibiting Wnt Signaling in Colorectal Cancer.
Cell line, Treatment
View SamplesThis SuperSeries is composed of the SubSeries listed below.
SOX2 is an oncogene activated by recurrent 3q26.3 amplifications in human lung squamous cell carcinomas.
Specimen part
View SamplesWe have identified SOX2 as a new oncogene and a likely driver of recurrent 3q26.3 amplifications in lung Squamous Cell Carcinoma. SOX2 is a crucial transcription factor implicated in Embryonic and Neural Stem Cells, that we found widely activatd in human lung SCC. This part of the study aimed at analyzing the transcriptomic consequences of SOX2 overexpression in a simple in vitro model (human lung squamous immortalized cells).
SOX2 is an oncogene activated by recurrent 3q26.3 amplifications in human lung squamous cell carcinomas.
Specimen part
View SamplesPurpose: To determine global gene expression changes following siRNA knockdown of Myc, Kcnk1, and Snta1 compared to non-targeting siRNAs or mock-transfected cells Methods: Total RNA was processed using the Illumina TruSeq Stranded mRNA Sample Preparation Kit according to manufacturer's protocol. Generated cDNA libraries were sequenced using an Illumina HiSeq 2000 sequencer with four biological replicates sequenced per condition using single read, 50 cycle runs. Quality of sequencing reads were assessed using FastQC (Babraham Bioinformatics) and then aligned to a reference genome (hg19, UCSC Genome Browser) using TopHat. Sequencing yielded, on average, 23.7 million unique reads per sample with a 60.7 - 65.7% mapping rate. Cufflinks was used to generate transcript abundance for each annotated protein-coding gene as Fragments Per Kilobase of transcript per Million mapped reads (FPKM), and statistical analysis and comparison of FPKM values was calculated using R (Bioconductor). Results: Fold changes comparing mock and a non-targeting siRNA were highly congruent. Myc RNAi induced numerous changes, with 955 downregulated genes and 1214 upregulated genes. The effect on Myc itself was relatively modest, possibly reflecting its ability to negatively auto-regulate its own expression. Gene ontology analysis highlighted ribosome biogenesis, metabolism, gene expression, cell cycle, and apoptosis pathways, consistent with known Myc functions. The Kcnk1 siRNA affected 424 genes, with KCNK1 itself one of the most repressed. While gene ontology analysis also highlighted metabolism and biosynthesis pathways, the p-values and fold enrichment scores were substantially lower, indicating that DiM can be suppressed without major effects on metabolism and biosynthesis pathways. The Snta1 siRNA deregulated 575 genes, with SNTA1 itself the most repressed gene. Cell cycle and mitosis-related gene ontology terms feature heavily, consistent with this siRNA accelerating mitotic exit. Interestingly, FoxM1, which drives G2/M gene expression was reduced 1.75-fold, indicating that this siRNA may disrupt mitotic controls by deregulating FoxM1. Conclusions: Global gene expression profiling identifies Egr1 as regulator of mitotic cell fate. Overall design: Total RNA was extracted from at least four replicates of siRNA-transfected cells and libraries for sequencing was prepared for each replicate.
MYC Is a Major Determinant of Mitotic Cell Fate.
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View SamplesRecent studies have suggested increased plasticity of differentiated cells within the intestine to act both as intestinal stem cells and tumour initiating cells. However, little is known of the processes that regulate this plasticity. Our previous work has shown that activating mutations of Kras or the NF-kB pathway can drive dedifferentiation of intestinal cells lacking Apc.
TGFβ pathway limits dedifferentiation following WNT and MAPK pathway activation to suppress intestinal tumourigenesis.
Specimen part
View SamplesRecent studies have suggested increased plasticity of differentiated cells within the intestine to act both as intestinal stem cells and tumour initiating cells. However, little is known of the processes that regulate this plasticity. Our previous work has shown that activating mutations of Kras or the NF-kB pathway can drive dedifferentiation of intestinal cells lacking Apc.
TGFβ pathway limits dedifferentiation following WNT and MAPK pathway activation to suppress intestinal tumourigenesis.
No sample metadata fields
View SamplesLIN28 is a conserved RNA binding protein implicated in pluripotency, reprogramming and oncogenesis. Previously shown to act primarily by blocking let-7 microRNA (miRNA) biogenesis, here we elucidate distinct roles of LIN28 regulation via its direct messenger RNA (mRNA) targets. Through cross-linking and immunoprecipitation coupled with high-throughput sequencing (CLIP-seq) in human embryonic stem cells and somatic cells expressing exogenous LIN28, we have defined discrete LIN28 binding sites in a quarter of human transcripts. These sites revealed that LIN28 binds to GGAGA sequences enriched within loop structures in mRNAs, reminiscent of its interaction with let-7 miRNA precursors. Among LIN28 mRNA targets, we found evidence for LIN28 autoregulation and also direct but differing effects on the protein abundance of splicing regulators in somatic and pluripotent stem cells. Splicing-sensitive microarrays demonstrated that exogenous LIN28 expression causes widespread downstream alternative splicing changes. These findings identify important regulatory functions of LIN28 via direct mRNA interactions. Overall design: CLIP-seq for LIN28-V5 in stable human Flp-In-293 cells, and LIN28 in hES cells; strand-specific mRNA-seq for uninfected, control KD, and LIN28 KD human H9 ES cells; and strand-specific smallRNA-seq for uninfected, control KD, and LIN28 KD human H9 ES cells.
LIN28 binds messenger RNAs at GGAGA motifs and regulates splicing factor abundance.
Cell line, Treatment, Subject
View SamplesCross-linking and immunoprecipitation coupled with high-throughput sequencing was used to identify binding sites within 6,304 genes as the brain RNA targets for TDP-43, an RNA binding protein which when mutated causes Amyotrophic Lateral Sclerosis (ALS). Use of massively parallel sequencing and splicing-sensitive junction arrays revealed that levels of 601 mRNAs are changed (including Fus/Tls, progranulin, and other transcripts encoding neurodegenerative disease-associated proteins) and 965 altered splicing events are detected (including in sortilin, the receptor for progranulin), following depletion of TDP-43 from adult brain with antisense oligonucleotides. RNAs whose levels are most depleted by reduction in TDP-43 are derived from genes with very long introns and which encode proteins involved in synaptic activity. Lastly, TDP-43 was found to auto-regulate its synthesis, in part by directly binding and enhancing splicing of an intron within the 3’ untranslated region of its own transcript, thereby triggering nonsense mediated RNA degradation. Overall design: RNAseq in control and Tdp-43 knockdown mouse striatum
Long pre-mRNA depletion and RNA missplicing contribute to neuronal vulnerability from loss of TDP-43.
No sample metadata fields
View SamplesCross-linking and immunoprecipitation coupled with high-throughput sequencing was used to identify binding sites within 6,304 genes as the brain RNA targets for TDP-43, an RNA binding protein which when mutated causes Amyotrophic Lateral Sclerosis (ALS). Use of massively parallel sequencing and splicing-sensitive junction arrays revealed that levels of 601 mRNAs are changed (including Fus/Tls, progranulin, and other transcripts encoding neurodegenerative disease-associated proteins) and 965 altered splicing events are detected (including in sortilin, the receptor for progranulin), following depletion of TDP-43 from adult brain with antisense oligonucleotides. RNAs whose levels are most depleted by reduction in TDP-43 are derived from genes with very long introns and which encode proteins involved in synaptic activity. Lastly, TDP-43 was found to auto-regulate its synthesis, in part by directly binding and enhancing splicing of an intron within the 3’ untranslated region of its own transcript, thereby triggering nonsense mediated RNA degradation. Overall design: CLIP of Tdp-43 in 8 week mouse brain.
Long pre-mRNA depletion and RNA missplicing contribute to neuronal vulnerability from loss of TDP-43.
No sample metadata fields
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