While prion infections have been extensively characterized in the laboratory mouse, little is known regarding the molecular responses to prions in other rodents. To explore these responses and make comparisons, we generated a prion disease in the laboratory rat by successive passage of mouse RML prions. Here we describe the accumulation of prions and associated pathology in the rat and describe the transcriptional impact throughout prion disease. Comparative transcriptional profiling between laboratory mice and rats suggests that similar molecular processes are unfolding in response to prion infection. At the level of individual transcripts, however, variability exists between mice and rats and many genes deregulated in mouse scrapie are not affected in rats. Notwithstanding these differences, many transcriptome responses are conserved between mice and rats infected with scrapie. Our findings highlight the usefulness of comparative approaches to understanding neurodegeneration and prion diseases in particular.
Transcriptomic responses to prion disease in rats.
Specimen part, DiseaseView Samples
Muscle tissue was longitudinally characterized histologically for electron transport function by staining 1mm of quadriceps muscle at 70 micron intervals for the activities of two complexes in the mitochondrial electron transport chain, Cytochrome C Oxidase and Succinate Dehydrogenase. Unstained serial cryosections were prepared for Laser Capture Microdissection. Target cells from the serial sections were isolated and pooled for RNA extraction, amplification and hybridization on Affymetrix microarrays. We selected homogeneous populations of muscle fibers for expression profiling based upon the presence/absence of electron transport dysfunction caused by the somatic accumulation of mitochondrial DNA deletion mutations.
Mitochondrial biogenesis drives a vicious cycle of metabolic insufficiency and mitochondrial DNA deletion mutation accumulation in aged rat skeletal muscle fibers.
Age, Specimen partView Samples
Overexpression of ecotropic viral integration site 1 (EVI1) is associated with aggressive disease in acute myeloid leukemia (AML). Despite of its clinical importance, little is known about the mechanism through which EVI1 confers resistance to antileukemic drugs. Here, we show that a human myeloid cell line constitutively overexpressing EVI1 after infection with a retroviral vector (U937_EVI1) was partially resistant to etoposide and daunorubicin as compared to empty vector infected control cells (U937_vec). Similarly, inducible expression of EVI1 in HL-60 cells decreased their sensitivity to daunorubicin. Gene expression microarray analyses of U937_EVI1 and U937_vec cells cultured in the absence or presence of etoposide showed that 77 and 419 genes were regulated by EVI1 and etoposide, respectively. Notably, mRNA levels of 26 of these genes were altered by both stimuli, indicating that EVI1 regulated genes were strongly enriched among etoposide regulated genes and vice versa. One of the genes that were induced by both EVI1 and etoposide was CDKN1A/p21/WAF, which in addition to its function as a cell cycle regulator plays an important role in conferring chemotherapy resistance in various tumor types. Indeed, overexpression of CDKN1A in U937 cells mimicked the phenotype of EVI1 overexpression, similarly conferring partial resistance to antileukemic drugs.
EVI1 inhibits apoptosis induced by antileukemic drugs via upregulation of CDKN1A/p21/WAF in human myeloid cells.
Cell line, TreatmentView Samples
To validate the suitability of two commonly used colorectal cancer cell lines, DLD1 and SW480, as model systems to study colorectal carcinogenesis, we treated these cell lines with -catenin siRNA and identified -catenin target genes using DNA microarrays. The list of identified target genes was compared to previously published -catenin target genes found in the PubMed and the GEO databases.
Comprehensive analysis of β-catenin target genes in colorectal carcinoma cell lines with deregulated Wnt/β-catenin signaling.
Cell line, TreatmentView Samples
Models for tumorigenesis can be made by transforming normal cells with defined genetic elements. This allows us to determine that adrenocortical tumor development and progression follows a multistep model. Morever, we demonstrated that the order of genetic events has a great consequence on the phenotype of the resultant tumor. We performed transcriptomic analysis using cDNA microarrays to identify the molecular signature that might explain the distinctive in vivo phenotypes observed in response to both orders of the mutational events.
Acquisition order of Ras and p53 gene alterations defines distinct adrenocortical tumor phenotypes.
Specimen partView Samples
To identify proteins regulated by glucose through changes in their rate of protein synthesis, translational profiling of MIN6 cells acutely incubated at either low or high glucose concentration was performed (i.e. microarray analysis was performed on mRNAs associated with polysomes, as an increase in the association of mRNA with polysomes is indicative of an increase in the rate of initiation step of translation and hence an increase in protein expression) (Johannes et al., 1999; Mikulits et al., 2000).
Distinct glucose-dependent stress responses revealed by translational profiling in pancreatic beta-cells.
Specimen part, Cell line, Compound, TimeView Samples
We conducted a set of lab-evolution experiments in yeast and followed the long-term dynamics of aneuploidy under diverse conditions including heat shock and high PH.
Chromosomal duplication is a transient evolutionary solution to stress.
No sample metadata fieldsView Samples
Prion infection in animals results in neurodegeneration and eventually death. To examine the cellular impact of Prion disease, we profiled non-proliferative fully differentiated C2C12 cells, which can replicate prions to high levels. Results suggest that accumulation of high levels of PrPSc in C2C12 myotubes does not cause any overt cellular dysfunction or molecular pathology.
Infectious prions accumulate to high levels in non proliferative C2C12 myotubes.
Specimen part, Cell line, Treatment, TimeView Samples
Mesenchymal stromal cells (MSC) are currently being evaluated in numerous preclinical and clinical cell-based therapy studies. Furthermore, there is an increasing interest in exploring alternative uses of these cells in disease modelling, pharmaceutical screening and regenerative medicine by applying reprogramming technologies. However, the limited availability of MSCs from various sources, restricts their use. Term amniotic fluid has been proposed as an alternative source of MSCs. Previously, only low volumes of term fluid and its cellular constituents have been collected, and current knowledge of the MSCs derived from this fluid is limited. In this study, we collected amniotic fluid at term using a novel collection system and evaluated amniotic fluid MSC content and their characteristics, including their feasibility to undergo cellular reprogramming.
Term amniotic fluid: an unexploited reserve of mesenchymal stromal cells for reprogramming and potential cell therapy applications.
Specimen partView Samples
HIV Tg rats exhibit pulmonary hypertension and pulmonary artery remodeling. In an effort to begin to understand cell signaling pathways which are altered in lungs from HIV transgenic rats, we used microarray analysis.
Human immunodeficiency virus transgenic rats exhibit pulmonary hypertension.
Sex, Age, Specimen partView Samples