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PrP Molecules (prp + molecule)
Selected AbstractsNerve Growth Factor-Induced Differentiation Does Not Alter the Biochemical Properties of a Mutant Prion Protein Expressed in PC12 CellsJOURNAL OF NEUROCHEMISTRY, Issue 1 2000Roberto Chiesa Abstract : Insertional and point mutations in the gene encoding the prion protein (PrP) are responsible for familial prion diseases. We have previously generated lines of Chinese hamster ovary cells that express PrP molecules carrying pathogenic mutations, and found that the mutant proteins display several biochemical properties reminiscent of PrPSc, the infectious isoform of PrP. To analyze the properties and effects of mutant PrP molecules expressed in cells with a neuronal phenotype, we have constructed stably transfected lines of PC12 cells that synthesize a PrP molecule carrying a nine-octapeptide insertion. We report here that this mutant PrP acquires scrapie-like properties, including detergent insolubility, protease resistance, and resistance to phospholipase cleavage of its glycolipid anchor. A detergent-insoluble and phospholipase-resistant form of the mutant protein is also released spontaneously into conditioned medium. These scrapie-like biochemical properties are quantitatively similar to those seen in Chinese hamster ovary cells and are not affected by differentiation of the PC12 cells into sympathetic neurons by nerve growth factor. Moreover, there is no detectable effect of mutant PrP expression on the morphology or viability of the cells in either the differentiated or undifferentiated state. These results indicate that conversion of mutant PrP into a PrPSc -like form does not depend critically on the cellular context, and they suggest that mutant PrP expressed in cultured cells, even those having the phenotype of differentiated neurons, is not neurotoxic. [source] The prion/lipid hypothesis , further evidence to support the molecular basis for transmissible spongiform encephalopathy risk assessmentJOURNAL OF APPLIED MICROBIOLOGY, Issue 6 2007P. Gale Summary Defining the molecular structure of the transmissible spongiform encephalopathy (TSE) agent is important both for underpinning risk assessments and for developing and understanding decontamination strategies. Recent studies have shown that oligomeric particles comprising 14,28 prion protein (PrP) molecules are much more infectious than larger fibrils (prion rods) or indeed smaller oligomers (trimers) and PrP monomers. Here, results from deactivation studies (with alkali, heat, hexane or formaldehyde) are interpreted in terms of the infectious nucleation seed comprising 14,28 PrP molecules held together by interactions with amphipathic phospholipid (PL) or more probably sphingolipid (SL) from the host. According to the PrP/lipid hypothesis, the strength of the protein/lipid interactions accounts for the high thermostability of TSE infectivity and for differences in thermostability between strains. The implications of the molecular biophysics data for environmental TSE risk assessments are discussed with respect to behaviour in soil. While formaldehyde appears to cause inactivation of scrapie infectivity by increasing the ID50, the dose,response is complicated by apparent heterogeneity between hamster subpopulations in susceptibility. The process of inactivation by formaldehyde may be due to cross-linking the highly infectious 14,28 PrP oligomers into larger, but less infectious aggregates. This process appears more reversible in some hamster subpopulations than others. [source] Post-transcriptional suppression of pathogenic prion protein expression in Drosophila neuronsJOURNAL OF NEUROCHEMISTRY, Issue 6 2003Nathan R. Deleault Abstract A wealth of evidence supports the view that conformational change of the prion protein, PrPC, into a pathogenic isoform, PrPSc, is the hallmark of sporadic, infectious, and inherited forms of prion disease. Although the central role played by PrPSc in the pathogenesis of prion disease is appreciated, the cellular mechanisms that recognize PrPSc and modulate its production, clearance, and neural toxicity have not been elucidated. To address these questions, we used a tissue-specific expression system to express wild-type and disease-associated PrP molecules heterologously in Drosophila melanogaster. Our results indicate that Drosophila brain possesses a specific and saturable mechanism that suppresses the accumulation of PG14, a disease-associated insertional PrP mutant. We also found that wild-type PrP molecules are maintained in a detergent-soluble conformation throughout life in Drosophila brain neurons, whereas they become detergent-insoluble in retinal cells as flies age. PG14 protein expression in Drosophila eye did not cause retinal pathology. Our work reveals the presence of mechanisms in neurons that specifically counterbalance the production of misfolded PrP conformations, and provides an opportunity to study these processes in a model organism amenable to genetic analysis. [source] Nerve Growth Factor-Induced Differentiation Does Not Alter the Biochemical Properties of a Mutant Prion Protein Expressed in PC12 CellsJOURNAL OF NEUROCHEMISTRY, Issue 1 2000Roberto Chiesa Abstract : Insertional and point mutations in the gene encoding the prion protein (PrP) are responsible for familial prion diseases. We have previously generated lines of Chinese hamster ovary cells that express PrP molecules carrying pathogenic mutations, and found that the mutant proteins display several biochemical properties reminiscent of PrPSc, the infectious isoform of PrP. To analyze the properties and effects of mutant PrP molecules expressed in cells with a neuronal phenotype, we have constructed stably transfected lines of PC12 cells that synthesize a PrP molecule carrying a nine-octapeptide insertion. We report here that this mutant PrP acquires scrapie-like properties, including detergent insolubility, protease resistance, and resistance to phospholipase cleavage of its glycolipid anchor. A detergent-insoluble and phospholipase-resistant form of the mutant protein is also released spontaneously into conditioned medium. These scrapie-like biochemical properties are quantitatively similar to those seen in Chinese hamster ovary cells and are not affected by differentiation of the PC12 cells into sympathetic neurons by nerve growth factor. Moreover, there is no detectable effect of mutant PrP expression on the morphology or viability of the cells in either the differentiated or undifferentiated state. These results indicate that conversion of mutant PrP into a PrPSc -like form does not depend critically on the cellular context, and they suggest that mutant PrP expressed in cultured cells, even those having the phenotype of differentiated neurons, is not neurotoxic. [source] Octapeptide repeat insertions increase the rate of protease-resistant prion protein formationPROTEIN SCIENCE, Issue 3 2006Roger A. Moore PrP, prion protein; HaPrP, hamster prion protein; TSE, transmissible spongiform encephalopathies Abstract A central feature of transmissible spongiform encephalopathies (TSE or prion diseases) involves the conversion of a normal, protease-sensitive glycoprotein termed prion protein (PrP-sen) into a pro-tease-resistant form, termed PrP-res. The N terminus of PrP-sen has five copies of a repeating eight amino acid sequence (octapeptide repeat). The presence of one to nine extra copies of this motif is associated with a heritable form of Creutzfeld-Jakob disease (CJD) in humans. An increasing number of octapeptide repeats correlates with earlier CJD onset, suggesting that the rate at which PrP-sen misfolds into PrP-res may be influenced by these mutations. In order to determine if octapeptide repeat insertions influence the rate at which PrP-res is formed, we used a hamster PrP amyloid-forming peptide (residues 23,144) into which two to 10 extra octapeptide repeats were inserted. The spontaneous formation of protease-resistant PrP amyloid from these peptides was more rapid in response to an increased number of octapeptide repeats. Furthermore, experiments using full-length glycosylated hamster PrP-sen demonstrated that PrP-res formation also occurred more rapidly from PrP-sen molecules expressing 10 extra copies of the octapeptide repeat. The rate increase for PrP-res formation did not appear to be due to any influence of the octapeptide repeat region on PrP structure, but rather to more rapid binding between PrP molecules. Our data from both models support the hypothesis that extra octapeptide repeats in PrP increase the rate at which protease resistant PrP is formed which in turn may affect the rate of disease onset in familial forms of CJD. [source] |