Project description:Mammalian prion diseases are fatal and transmissible neurological conditions caused by the propagation of prions, self-replicating multimeric assemblies of misfolded forms of host cellular prion protein. Despite extensive studies investigating the changes in transcriptional profiles in prion diseases the mechanisms by which prion diseases induce cellular toxicity, including changes in gene expression profiles are yet to be fully characterized. Here, we took advantage of the recent developments in single-cell technologies and performed an unbiased whole-transcriptome single-nucleus transcriptomic analysis in prion disease.
Project description:Mammalian prion diseases are fatal and transmissible neurological conditions caused by the propagation of prions, self-replicating multimeric assemblies of misfolded forms of host cellular prion protein. Despite extensive studies investigating the changes in transcriptional profiles in prion diseases the mechanisms by which prion diseases induce cellular toxicity, including changes in gene expression profiles are yet to be fully characterized. Here, we took advantage of the recent developments in single-cell technologies and performed an unbiased whole-transcriptome single-nucleus transcriptomic analysis in prion disease.
Project description:Mammalian prion diseases are fatal and transmissible neurological conditions caused by the propagation of prions, self-replicating multimeric assemblies of misfolded forms of host cellular prion protein. Despite extensive studies investigating the changes in transcriptional profiles in prion diseases the mechanisms by which prion diseases induce cellular toxicity, including changes in gene expression profiles are yet to be fully characterized. Here, we took advantage of the recent developments in single-cell technologies and performed an unbiased whole-transcriptome single-nucleus transcriptomic analysis in prion disease.
Project description:Prion diseases are fatal transmissible neurodegenerative conditions of humans and animals that arise through neurotoxicity induced by PrP misfolding. The cellular and molecular mechanisms of prion-induced neurotoxicity remain undefined. Understanding these processes will underpin therapeutic and control strategies for human and animal prion diseases, respectively. Prion diseases are difficult to study in their natural hosts and require the use of tractable animal models. Here we used RNA-Seq-based transcriptome analysis of prion-exposed Drosophila to probe the mechanism of prion-induced neurotoxicity. Adult Drosophila transgenic for pan neuronal expression of ovine PrP targeted to the plasma membrane exhibit a neurotoxic phenotype evidenced by decreased locomotor activity after exposure to ovine prions at the larval stage. Pathway analysis and quantitative PCR of genes differentially expressed in prion-infected Drosophila revealed up-regulation of cell cycle activity and DNA damage response, followed by down-regulation of eIF2 and mTOR signalling. Mitochondrial dysfunction was identified as the principal toxicity pathway in prion-exposed PrP transgenic Drosophila. The transcriptomic changes we observed were specific to PrP targeted to the plasma membrane since these prion-induced gene expression changes were not evident in similarly-treated Drosophila transgenic for cytosolic pan neuronal PrP expression, or in non-transgenic control flies. Collectively, our data indicate that aberrant cell cycle activity, repression of protein synthesis and altered mitochondrial function are key events involved in prion-induced neurotoxicity, and correlate with those identified in mammalian hosts undergoing prion disease. These studies highlight the use of PrP transgenic Drosophila as a genetically well-defined tractable host to study mammalian prion biology.
Project description:Selective neuronal vulnerability is a common, yet poorly understood characteristic of neurodegenerative diseases and is particularly prominent in familial prion diseases, such as Creutzfeldt-Jakob disease (CJD) and fatal familial insomnia (FFI), where different mutations in the prion protein manifest as neuropathologically distinct diseases. To determine how presence of mutant prion protein influences gene expression at pre-symptomatic stages, we used RiboTag to isolate cell type-specific, translating RNA from GABAergic, glutamatergic, somatostatin- (SST) and parvalbumin-expressing neurons of 9-month-old knock-in mice of CJD and FFI.
Project description:The underlying pathogenic mechanisms of prion infection are not well characterized. To study the effect of prion infection on gene expression in neuronal cell cultures, a neuroblastoma (N2a) cell clone was infected with either the mouse adapted prion strain 22L or exposed to uninfected brain homogenate as a negative control. Large scale expression analysis was performed using a cDNA microarray chip comprising about 21,000 spotted ESTs. Over hundred genes were identified that are differentially expressed in 22L-infected cells when compared to uninfected cells. Several of the identified changes in gene expression have also been reported for other neurodegenerative diseases such as Alzheimer`s disease. Keywords: cDNA arrays, prion, N2a, neuroblastoma cell line, murine A neuroblastoma (N2a) cell clone was infected with either the mouse adapted prion strain 22L or exposed to uninfected brain homogenate as a negative control. Eight replicates including four dye swap experiments have been performed for the comparison of prion infected cells versus control cells.
Project description:In neurodegenerative diseases, including prion diseases, cellular models arise as useful tools to study the pathogenic mechanisms occurring in these diseases and to assess the efficacy of potential therapeutic compounds. In the present study, a RNA-sequencing analysis of bone marrow-derived ovine mesenchymal stem cells (oBM-MSCs) infected with scrapie was performed to try to unravel genes and pathways potentially involved with prion disease mechanisms and to assess the potential of these cells to act as in vitro models of prion toxicity. oBM-MSCs were cultured in three different conditions: inoculated with brain homogenate of scrapie-infected sheep, with brain homogenate of healthy sheep and in standard growth conditions without inoculum. The cell viability and presence of prions was determined. In the transcriptomic analysis the three conditions were analysed in two infection times: 2 and 4 days’ post-inoculation (dpi). Differentially expressed genes in scrapie-infected oBM-MSCs were found in the two infection times finding the higher number at 2 dpi. These genes were also enriched in multiple pathways and biological functions related with prion replication and toxicity. Moreover, a set of 11 genes was selected for a validation study, having 7 of these genes significant expression changes in scrapie-infected cells and functions related with prion propagation and its associated toxicity. These results indicate that ovine mesenchymal stem cells infected with scrapie could be useful in vitro models to study prion toxicity mechanisms and to test anti-prion compounds.
Project description:Background: Prion diseases such as bovine spongiform encephalopathies (BSE) are transmissible neurodegenerative diseases which are presumably caused by an infectious conformational isoform of the cellular prion protein. Previous work has provided evidence that in murine prion disease the endogenous retrovirus (ERV) expression is altered in the brain. To determine if prion-induced changes in ERV expression are a general phenomenon we used a non-human primate model for prion disease. Results: Cynomolgus macaques (Macaca fasicularis) were infected intracerebrally with BSE-positive brain stem material from cattle and allowed to develop prion disease. Brain tissue from the basis pontis and vermis cerebelli of the six animals and the same regions from four healthy controls were subjected to ERV expression profiling using a retrovirus-specific microarray and quantitative real-time PCR. We could show that Class I gammaretroviruses HERV-E4-1, ERV-9, and MacERV-4 increase expression in BSE-infected macaques. In a second approach, we analysed ERV-K-(HML-2) RNA and protein expression in extracts from the same cynomolgus macaques. Here we found a significant downregulation of both, the macaque ERV-K-(HML-2) Gag protein and RNA in the frontal/parietal cortex of BSE-infected macaques. Conclusions: We provide evidence that dysregulation of ERVs in response to BSE-infection can be detected on both, the RNA and the protein level. To our knowledge, this is the first report on the differential expression of ERV-derived structural proteins in prion disorders. Our findings suggest that endogenous retroviruses may induce or exacerbate the pathological consequences of prion-associated neurodegeneration. Cynomolgus macaques (Macaca fasicularis) were infected intracerebrally with BSE-positive brain stem material from cattle and allowed to develop prion disease. Brain tissue from the basis pontis and vermis cerebelli of the six animals and the same regions from four healthy controls were subjected to ERV expression profiling using a retrovirus-specific microarray and quantitative real-time PCR. In a second approach, ERV-K-(HML-2) RNA and protein expression was analysed in extracts from the same cynomolgus macaques.
Project description:Of all neurodegenerative pathologies, prion diseases exhibit one of the most extensive neuroinflammatory phenotypes, yet the impact of neuroinflammation on the course of the disease is anything but clear . Prions trigger conspicuous proliferation of microglial cells, which may contribute to neuronal damage but are also involved in prion clearance . We approached these questions by establishing a spatial-transcriptomic atlas of the progression of prion disease, and identified GPNMB gene as the most enriched one in a subset of microglial cells with enhanced phagocytic activity present only in prion-infected mice. This cell type responded to ongoing apoptosis in distinct brain regions from 30 weeks post-prion inoculation and progressively increased up to the terminal stage of the disease.