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Altered DNA methylation profiles in blood from patients with sporadic Creutzfeldt-Jakob disease

ABSTRACT: Prion diseases are fatal and transmissible neurodegenerative disorders caused by the misfolding and aggregation of prion protein. Although recent studies have implicated epigenetic variation in common neurodegenerative disorders, no study has yet explored their role in human prion diseases. Here we profiled genome-wide blood DNA methylation in the most common human prion disease, sporadic Creutzfeldt-Jakob disease (sCJD). Our case-control study (n=219), when accounting for differences in cell type composition between individuals, identified 38 probes at genome-wide significance (p < 1.24x10-7). Nine of these sites were taken forward in a replication study, performed in an independent case-control (n=186) cohort using pyrosequencing. Sites in or close to FKBP5, AIM2 (2 probes), UHRF1, KCNAB2, PRNP, ANK1 successfully replicated. The blood-based DNA methylation signal was tissue- and disease-specific, in that the replicated probe signals were unchanged in case-control studies using sCJD frontal-cortex (n=84), blood samples from patients with Alzheimer’s disease, and from inherited and acquired prion diseases. Machine learning algorithms using blood DNA methylation array profiles accurately distinguished sCJD patients and controls. Finally, we identified sites whose methylation levels associated with prolonged survival in sCJD patients. Altogether, this study has identified a peripheral DNA methylation signature of sCJD with a variety of potential biomarker applications.

ORGANISM(S): Homo sapiens

PROVIDER: GSE156994 | GEO | 2020/10/19

REPOSITORIES: GEO

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Project description:Human prion diseases are fatal neurodegenerative disorders characterized by neuronal damage in brain. Protein S-nitrosylation, the covalent adduction of a NO to cysteine, plays a role in human brain biology, and brain dysfunction is a prominent feature of pPrion disease, yet the direct brain targets of S-nitrosylation are largely unknown. We described the first proteomic analysis of global S-nitrosylation in brain tissues of sporadic Creutzfeldt–Jakob disease (sCJD), fatal familial insomnia (FFI) and genetic CJD with a substitution of valine for glycine at codon 114 of the prion protein gene (G114V gCJD) accompanying with normal control with isobaric tags for relative and absolute quantitation (iTRAQ) combined with a nano-HPLC/Q Exactive Mass spectrometry platform. In parallel, we used several approaches to provide quality control for the experimentally defined S-nitrosylated proteins. Total 1509 S-nitrosylated proteins (SNO-proteins) were identified, and cerebellum tissues appeared to contain more commonly differentially expressed SNO-proteins (DESPs) than cortex of sCJD, FFI and gCJD. Three selected SNO-proteins were verified by Western blots, consistent with proteomics assays. Gene ontology analysis showed that more up-regulated DESPs were involved in metabolism, cell cytoskeleton/structure and immune system both in cortex and cerebellum, while more down-regulated ones in both regions were involved in cell cytoskeleton/structure, cell-cell communication and miscelaneous function protein. Pathway analysis suggested that systemic lupus erythematosus, pathogenic Escherichia coli infection, extracellular matrix-receptor interaction were the most commonly affected pathways, which were identified from at least two different diseases. Using STRING database, the network of immune system and cell cytoskeleton and structure were commonly identified in the context of the up-regulated and down-regulated DESPs, respectively, both in cortex and cerebellum. Our study thus have implications for understanding the molecular mechanisms of human prion diseases related to abnormal protein S-nitrosylation and pave the way for future studies focused on potential biomarkers for the diagnosis and therapy of human prion diseases.

Project description:The familial or genetic Creutzfeldt-Jakob disease (fCJD or gCJD) is the inherent form of human prion diseases, which accounts for approximately 10-15% of human prion diseases that are caused by mutations of the prion protein gene (PRNP). In this study, the global expression patterns of the parietal cortex from a patient with G114V gCJD were comparatively analyzed with the normal controls by using a commercial human genome expression chip. Totally 8774 genes showed differential expression, among them 2769 genes were upregulated and 6005 ones were downregulated. The reliability of the results was confirmed by the real-time RT-PCR assays for several specific genes. The most differentially expressed genes involved in the functions of regulation of transcription, ion transport, transcription, cell adhesion, signal transduction. The gene associated with gliosis was upregulated and the genes marked for neurons were downregulated, while the transcription of PRNP gene maintained unchanged. 169 different pathways showed significantly changed in the brain of G114V gCJD. The most significantly regulated pathways included that of Alzheimer’s and Parkinson’s disease, oxidative phosphorylation, regulation of actin cytoskeleton, MAPK signaling pathway and proteasome, which were described in prion diseases previously. In addition, some rarely addressed pathways in prion diseases, such as axon guidance, gap junction and purine metabolism, were also significantly changed in G114V gCJD. The transcriptional situations of the most genes in the top ten changed pathways were down-regulated. The extensive reductions of gene expressions in G114V gCJD showed the comparable profiles with sporadic CJD. The data here raised the useful clues for understanding the pathogenesis of the disease and selecting the potential biomarkers for diagnostic and therapeutic tools. Brain tissues of parietal cortex from a definitely diagnosed G114V gCJD were enrolled into this study. The patient was a 47-year-old Han-Chinese woman at the onset. Neuropathological assays of ten different brain regions revealed typical sCJD-like abnormality and PrPSc deposits. Meanwhile, a commercial normal human parietal cortex total RNA (Clontech) pooled from four male/female aged 35-89 was utilized as control.

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Altered DNA methylation profiles in blood from patients with sporadic Creutzfeldt-Jakob disease

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