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, Disease
View SamplesMuscle 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 part
View SamplesPrion 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, Time
View SamplesMedulloblastoma (MB) is the most common malignant primary pediatric brain tumor and is currently divided into 4 subtypes based on different genomic alterations, gene expression profiles and response to treatment: WNT, Sonic Hedgehog (SHH), Group 3 and Group 4. The extensive heterogeneity has made it difficult to assess the relevance of genes to malignant progression. For example, expression of the transcription factor, OTX2, is frequently dysregulated in multiple MB variants; however, it's role may be subtype specific. Here, we utilized human embryonic stem cell-derived neural precursors to determine the role of OTX2 in MB tumor progression using gain and loss of function studies.
OTX2 exhibits cell-context-dependent effects on cellular and molecular properties of human embryonic neural precursors and medulloblastoma cells.
Specimen part
View SamplesSpinocerebellar ataxia type 6 (SCA6) is a dominantly inherited neurodegenerative disease caused by an expansion of a CAG repeat encoding a polyglutamine (PolyQ) tract in the Cav2.1 voltage-gated calcium channel. Pathologically, it is characterized by selective degeneration of cerebellar Purkinje cells (PCs), which are a common target for PolyQ-induced toxicity among several different SCAs. Mutant Cav2.1 confers toxicity mainly through a toxic gain-of-function mechanism, but subcellular site of expanded Cav2.1 toxicity is controversial and it remains elusive whether SCA6 shares pathogenic cascades with other SCAs. To gain insight into these problems, we studied the cerebellar gene expression patterns of young Sca6 MPI 118Q/118Q knockin (KI) mice, which express mutant Cav2.1 from endogenous locus and faithfully models human SCA6. Comparison of transcriptional changes with those of Sca1 154Q/2Q mice, a faithful KI mouse model of SCA1, revealed that transcriptional signatures in the MPI 118Q/118Q were distinct from those of Sca1 154Q/2Q. Examination of temporal profiles of candidate genes showed that upregulation of those associated with microglial activation was initiated before PC degeneration was apparent and augmented as the disease progressed. Histological analysis of the MPI 118Q/118Q cerebellum confirmed the presence of Iba-1 positive activated microglia. Moreover, predominance of M1-like pro-inflammatory microglia was observed and was concomitant with the increased expression of pro-inflammatory cytokines. These results suggest that the unique transcriptional response, which highlights upregulation of neuroinflammatory genes possibly associated with lysosomal involvement, may play a pivotal role in the pathogenesis. Modulation of innate immune system could pave the way for slowing the progression of SCA6.
Loss of MyD88 alters neuroinflammatory response and attenuates early Purkinje cell loss in a spinocerebellar ataxia type 6 mouse model.
Specimen part
View SamplesThis SuperSeries is composed of the SubSeries listed below.
IDH2 and NPM1 Mutations Cooperate to Activate Hoxa9/Meis1 and Hypoxia Pathways in Acute Myeloid Leukemia.
Specimen part
View SamplesMutations in IDH1 and IDH2 are frequently observed in various cancers, including acute myeloid leukemia (AML). Mutant IDHs convert -ketoglutarate (-KG) to 2-hydroxyglutarate (2-HG), which dysregulates a set of-KG-dependent dioxygenases. To determine whether mutant IDHs are valid targets for cancer therapy, we established a mouse AML model harboring an IDH2 mutation by transplanting mice with nucleophosmin1 (NPM1)+/- mouse hematopoietic stem/progenitor cells that had been co-transduced with four mutant genes (NPMc, IDH2/R140Q, DNMT3A/R882H and FLT3/ITD) that frequently occur simultaneously in human AML patients. IDH2/R140Q is necessary for the engraftment or survival of NPMc+ cells in vivo.Gene-expression analysis indicated that NPMc increased the expression of Hoxa9, and that IDH2/R140Q increased the level of Meis1 and activated the hypoxia pathway in AML cells.Conditional deletion of IDH2/R140Q blocked 2-HG production and maintenance of leukemia stem cells, resulting in survival of the AML mice. IDH2/R140Q reversibly decreased the levels of 5hmC modification and gene expression at some differentiation inducing genes (Ebf1, Pax5 and Spib). These results indicate that the IDH2 mutation is critical for the development and maintenance of AML stem cells, and that mutant IDHs are promising targets for anticancer therapy.
IDH2 and NPM1 Mutations Cooperate to Activate Hoxa9/Meis1 and Hypoxia Pathways in Acute Myeloid Leukemia.
Specimen part
View SamplesBackground & Aims: Recent genomic studies have identified frequent mutations of AT-rich interactive domain 2 (ARID2) in hepatocellular carcinoma (HCC), but it is not still understood how ARID2 exhibits tumor suppressor activities. Methods: We established the ARID2 knockout HCC cell lines by using CRISPR/Cas9 system, and investigated the gene expression profiles and biological functions. Results: Bioinformatic analysis indicated that UV-response genes were negatively regulated in the ARID2-KO cells, and they were certainly sensitized to UV irradiation. ARID2 depletion attenuated nucleotide excision repair (NER) of DNA damage sites introduced by exposure to UV as well as chemical compounds known as carcinogens for HCC, benzo[a]pyrene and FeCl3, since XPG could not be accumulated without ARID2. By using large-scale public data sets, we validated that ARID2 knockout could lead to similar molecular changes between in vitro and in vivo, and moreover observed a higher number of somatic mutations in the ARID2-mutated subtypes than that in the ARID2 wild-type across various types of cancers including HCC. Conclusions: We provided evidence that ARID2 knockout could contribute to disruption of NER process through inhibiting the recruitment of XPG, resulting in susceptibility to carcinogens and potential hypermutation. These findings have far-reaching implications for therapeutic targets in cancers harboring ARID2 mutations.
Classification of primary liver cancer with immunosuppression mechanisms and correlation with genomic alterations.
Specimen part
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