In the current work, we add to the understanding of differentiated-cell-derived tumorigenesis by demonstrating that simultaneous loss of SMAD4 and activation of the WNT pathway triggers stem cell properties and adenoma formation in the differentiated epithelium. Under normal conditions, SMAD4 loss does not immediately affect the normal tissue homeostasis in the intestine. However, after approximately 6 months, adenomas will develop and feature elevated WNT signaling, suggesting that SMAD4 loss predisposes to WNT-driven tumors. Interestingly, ectopic elevation of WNT in the context of a SMAD4 mutant background triggers stem cell activity and adenoma formation in the differentiated epithelium. Thus Smad4 functions to suppress villus cells from re-entering the cell cycle and functioning as stem cells upon exposure to high levels of WNT. Thus, we report a new mechanism through which differentiated cells can contribute to tumor formation. Overall design: RNAs were extracted from crypt jejunal epithelia of the indicated genotypes (Smad4f/f;Villin-CreER(T2) and Smad4f/f; Ex3f/+;Villin-CreER(T2)) in triplicates, one day following 4 consecutive days of tamoxifen injection. Uninjected mice served as control. After flushing the freshly harvested jejunum with cold PBS, the epithelia was dissociated from underlying mesenchyme by incubating with 3 mM EDTA/PBS at 4°C as described previously (Perekatt, 2014), and filtered through 70 micron filter to isolate the crypts. The crypts were washed with PBS, and pelleted to remove excess PBS prior to addition of TRIzol for RNA extraction according to manufacturer's protocols.
SMAD4 Suppresses WNT-Driven Dedifferentiation and Oncogenesis in the Differentiated Gut Epithelium.
Specimen part, Treatment, Subject
View SamplesAEG-1 is overexpressed in human hepatocellular carcinoma (HCC) and positively regulates development and progression of HCC A conditional hepatocyte-specific knockout mouse was generated by crossing floxed AEG-1 mouse with Alb/Cre mouse in C57BL/6 background Overall design: Livers were harvested from chow-fed 12 wks old AEG-1fl/fl and AEG-1DHEP mice. RNA was extracted and subjected to RNA-Seq.
A novel role of astrocyte elevated gene-1 (AEG-1) in regulating nonalcoholic steatohepatitis (NASH).
Age, Specimen part, Subject
View SamplesRecently a new neonatal diabetes syndrome, Mitchell-Riley syndrome, was discovered. To identify the genetic cause of the syndrome homozygosity mapping was used, several chromosomal regions were linked to Mitchell-Riley syndrome. In situ hybridization of genes from one such region using model organism Xenopus laevis identified RFX6 as a potential candidate gene; mutant forms of RFX6 were subsequently found in Mitchell-Riley patients. Analysis of the expression pattern of RFX6 in Xenopus development shows it is expressed broadly in the endoderm early in development, and later RFX6 becomes restricted to the endocrine cells of the gut and pancreas. Morpholino knockdown of RFX6 in Xenopus caused a loss of pancreas marker gene expression. Injection of exogenous wild type RFX6 rescued the morpholino phenotype in Xenopus tadpoles. Attempts to rescue the loss-of-function phenotype using mutant forms of RFX6 found in Mitchell-Riley patients were unsuccessful suggesting the changes lead to loss-of-function and could be the cause of Mitchell-Riley syndrome. Microarray analysis of gene expression in knockdown tissue suggested a downregulation in marker genes for lung, stomach and heart, ambiguous results for the liver, and an upregulation in kidney marker gene expression. RT-PCR and in situ hybridization confirms a loss of lung, stomach and heart gene expression, no change in liver marker hex and an upregulation in kidney marker KcnJ1. The fact that the morpholino phenotype affects multiple organs suggests that RFX6 has a broad role early in endoderm development.
Functional analysis of Rfx6 and mutant variants associated with neonatal diabetes.
Specimen part, Treatment
View SamplesDuring embryogenesis, the pancreas develops from separate dorsal and ventral buds, which fuse to form the mature pancreas. Little is known about the functional differences between these two buds or the relative contribution of cells derived from each portion to the pancreas after fusion. To follow the fate of dorsal or ventral bud derived cells in the pancreas after fusion, we produced chimeric Elas-GFP transgenic/wild type embryos in which either dorsal or ventral pancreatic bud cells expressed GFP. We found that ventral pancreatic cells migrate extensively into the dorsal pancreas after fusion, whereas the converse does not occur. Moreover, we found that annular pancreatic tissue is composed exclusively of ventral pancreas derived cells. To identify ventral pancreas specific genes that may play a role in pancreatic bud fusion, we isolated individual dorsal and ventral pancreatic buds, prior to fusion, from stage 38/39 Xenopus laevis tadpoles and compared their gene expression profiles. Morpholino-mediated knockdown of one of these ventral specific genes, transmembrane 4 superfamily member 3 (tm4sf3), inhibited dorsal-ventral pancreatic bud fusion as well as acinar cell differentiation. Conversely, overexpression of tm4sf3 promoted the development of annular pancreas. Our results are the first to define molecular and behavioral differences between the dorsal and ventral pancreas, and suggest an unexpected role for the ventral pancreas in pancreatic bud fusion.
The tetraspanin Tm4sf3 is localized to the ventral pancreas and regulates fusion of the dorsal and ventral pancreatic buds.
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View SamplesPilocytic astrocytoma is the most common type of brain tumor in pediatric population, generally connected with favorable prognosis, although recurrences or dissemination sometimes are also observed. For tumors originating in supra- or infratentorial location different molecular background was suggested but plausible correlations between transcriptional profile and radiological features and/or clinical course are still undefined. The purpose of this study was to identify gene expression profiles related to the most frequent locations of this tumor, subtypes based on various radiological features and clinical pattern of the disease. According to the radiological features presented on MRI, all cases were divided into four subtypes: solid or mainly solid, cystic with an enhancing cyst wall, cystic with a non-enhancing cyst wall and solid with central necrosis. Bioinformatic analyses showed that gene expression profile of pilocytic astrocytoma highly depends on the tumor location. Most prominent differences were noted for IRX2, PAX3, CXCL14, LHX2, SIX6, CNTN1 and SIX1 genes expression which could distinguish pilocytic astrocytomas of different location even within supratentorial region. Analysis of the genes potentially associated between radiological features showed much weaker transcriptome differences. Single genes showed association with the tendency to progression. Here we showed that pilocytic astrocytomas of three different locations could be precisely differentiated on the basis of gene expression level but their transcriptional profiles did not strongly reflect the radiological appearance of the tumor or the course of the disease.
Transcriptional profiles of pilocytic astrocytoma are related to their three different locations, but not to radiological tumor features.
Sex, Age, Specimen part, Disease
View SamplesWe have characterized a mutation affecting the Arabidopsis EARLY IN SHORT DAYS 7 (ESD7) gene encoding the catalytic subunit of the DNA polymerase epsilon (e), AtPOL2A. esd7-1 mutations causes early flowering independently of photoperiod, shortened inflorescence internodes and altered leaf and root development. esd7-1 was a hypomorphic allele whereas KO alleles displayed an embryo-lethal phenotype. The SAM and the RAM in the esd7-1 seedlings were found to exhibit an altered disposition that might correlate with the abnormal expression pattern of SAM and RAM marker genes. esd7-1 showed higher sensitivity to DNA damaging reagents than wild type plants and altered expression of genes involved in DNA repair mechanisms by homologous recombination. Moreover, esd7 early flowering phenotype requires functional FT and SOC1 proteins and might be also related to the mis-regulation of AG and AG-like gene expression found in esd7. Loci involved in the modulation of the chromatin structural dynamics, such as TFL2 and EBS, which negatively regulate FT expression, were found to interact genetically with ESD7, and the carboxy terminus of ESD7 interacted with TFL2 in vitro. Besides, fasciata2 (fas2) mutations suppressed esd7 early flowering phenotype and INCURVATA 2 (ICU2) was found to be epistatic to ESD7. Discrete regions of the chromatin of FT and AG loci were enriched in activating epigenetic marks in the esd7-1 mutant. We concluded that ESD7 might be participating in processes involved in chromatin-mediated cellular memory.
EARLY IN SHORT DAYS 7 (ESD7) encodes the catalytic subunit of DNA polymerase epsilon and is required for flowering repression through a mechanism involving epigenetic gene silencing.
Specimen part
View SamplesWe have analyzed, using DNA microarrays, putative differences in gene-expression level between hereditary BRCA1 mutation-linked and sporadic breast cancer. Our results show that a previously reported marked difference between BRCA1-mutation linked and sporadic breast cancer was probably due to uneven stratification of samples with different ER status and basal-like versus luminal-like subtype. We observed that apparent difference between BRCA1-linked and other types of breast cancer found in univariate analysis was diminished when data were corrected for ER status and molecular subtype in multivariate analyses. In fact, the difference in gene expression pattern of BRCA1-mutated and sporadic cancer is very discrete. These conclusions were supported by the results of Q-PCR validation. We also found that BRCA1 gene inactivation due to promoter hypermethylation had similar effect on general gene expression profile as mutation-induced protein truncation. This suggests that in the molecular studies of hereditary breast cancer, BRCA1 gene methylation should be recognized and considered together with gene mutation.
BRCA1-related gene signature in breast cancer: the role of ER status and molecular type.
Age
View SamplesMolecular mechanisms of cell cycle exit are poorly understood. A group of genes required for cell cycle exit and maintenance of cell quiescence in human fibroblasts following serum deprivation has been recently identified. Studies on lymphocytes following growth factor deprivation-induced cell cycle exit have predominantly focused on the initiation of apoptosis. A set of genes involved in lymphocyte quiescence have also been identified among genes highly expressed in resting lymphocytes and down-regulated after cell activation. In our study, proliferating IL-2-dependent human T cells were forced to exit cell cycle by growth factor withdrawal, and their gene expression profiles were examined.
Molecular signature of cell cycle exit induced in human T lymphoblasts by IL-2 withdrawal.
No sample metadata fields
View SamplesWe report the role of SmE1 protein in the control of Arabidopsis development and tolerance to abiotic stresses. SmE1 controls gene expression reprogramming at the post-transcriptional level by promoting the splicing of pre-mRNA. This function is selectively achieve over selected transcripts depending on the stimulus nature. Overall design: Transcriptomic profiling through RNAseq of Col-0 and sme1-1 plants under control conditions or exposed to low temperatures (4ºC, 24h)
Arabidopsis SME1 Regulates Plant Development and Response to Abiotic Stress by Determining Spliceosome Activity Specificity.
Specimen part, Subject
View SamplesTranscriptome of S. cerevisiae in shifts between glucose and maltose media with different re-growth conditions Overall design: Cells are pregrown in maltose, then grown for different durations in glucose and then washed back to maltose
A new protocol for single-cell RNA-seq reveals stochastic gene expression during lag phase in budding yeast.
Subject
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