Showing papers by "Fabrizio Tagliavini published in 2007"

Conversion of the BASE Prion Strain into the BSE Strain: The Origin of BSE?

Abstract: Atypical neuropathological and molecular phenotypes of bovine spongiform encephalopathy (BSE) have recently been identified in different countries. One of these phenotypes, named bovine “amyloidotic” spongiform encephalopathy (BASE), differs from classical BSE for the occurrence of a distinct type of the disease-associated prion protein (PrP), termed PrPSc, and the presence of PrP amyloid plaques. Here, we show that the agents responsible for BSE and BASE possess different biological properties upon transmission to transgenic mice expressing bovine PrP and inbred lines of nontransgenic mice. Strikingly, serial passages of the BASE strain to nontransgenic mice induced a neuropathological and molecular disease phenotype indistinguishable from that of BSE-infected mice. The existence of more than one agent associated with prion disease in cattle and the ability of the BASE strain to convert into the BSE strain may have important implications with respect to the origin of BSE and spongiform encephalopathies in other species, including humans.

Neurotoxic and gliotrophic activity of a synthetic peptide homologous to Gerstmann-Sträussler-Scheinker disease amyloid protein

Abstract: Amyloid fibrils in Gerstmann-Straussler-Scheinker (GSS) disease are composed of a fragment of the prion protein (PrP), the N and C termini of which correspond to ragged residues 81-90 and 144-153. A synthetic peptide spanning the sequence 82-146 (PrP 82-146) polymerizes into protease-resistant fibrils with the tinctorial properties of amyloid. We investigated the biological activity of PrP 82-146 and of two nonamyloidogenic variants of PrP 82-146 with scrambled amino acid sequence 106-126 or 127-146. Cortical neurons prepared from rat and mouse embryos were chronically exposed to the PrP 82-146 peptides (10-50 microM). PrP 82-146 and the partially scrambled peptides induced neuronal death with a similar dose-response pattern, indicating that neurotoxicity was independent of amyloid fibril formation. Neurotoxicity was significantly reduced by coadministration of an anti-oligomer antibody, suggesting that PrP 82-146 oligomers are primarily responsible for triggering cell death. Neurons from PrP knock-out (Prnp0/0) mice were significantly less sensitive to PrP 82-146 toxicity than neurons expressing PrP. The gliotrophic effect of PrP 82-146 was determined by [methyl-3H]-thymidine incorporation in cultured astrocytes. Treatment with PrP 82-146 stimulated [methyl-3H]-thymidine uptake 3.5-fold. This activity was significantly less when the 106-126 or 127-146 regions were disrupted, indicating that PrP 82-146 amyloid activates the gliotrophic response. Prnp0/0 astrocytes were insensitive to the proliferative stimulus of PrP 82-146. These results underline the role of cerebral accumulation of abnormally folded PrP fragments and indicate that cellular PrP governs the pathogenic process.

The ε isoform of 14-3-3 protein is a component of the prion protein amyloid deposits of Gerstmann-Sträussler-Scheinker disease

Abstract: The 14-3-3 proteins are highly conserved, ubiquitous molecules involved in a variety of biologic events, such as transduction pathway modulation, cell cycle control, and apoptosis. Seven isoforms have been identified that are abundant in the brain, preferentially localized in neurons. Remarkable increases in 14-3-3 are seen in the cerebrospinal fluid of patients with Creutzfeldt-Jakob disease (CJD), and it has been found in pathologic inclusions of several neurodegenerative diseases. Moreover, the zeta isoform has been detected in prion protein (PrP) amyloid deposits of CJD patients. To further investigate the cerebral distribution of 14-3-3 in prion-related encephalopathies, we carried out an immunohistochemical and biochemical analysis of brain tissue from patients with Gerstmann-Straussler-Scheinker disease (GSS) and sporadic, familial and acquired forms of CJD, using specific antibodies against the seven 14-3-3 isoforms. The study showed a strong immunoreactivity of PrP amyloid plaques of GSS patients for the 14-3-3 epsilon isoform, but not for the other isoforms. The epsilon isoform of 14-3-3 was not found in PrP deposits of CJD. These results indicate that the epsilon isoform of 14-3-3 is a component of PrP amyloid deposits of GSS and suggest that this is the sole 14-3-3 isoform specifically involved in the neuropathologic changes associated with this disorder.

A novel phenotype of sporadic Creutzfeldt–Jakob disease

Abstract: An atypical case of sporadic Creutzfeldt–Jakob disease (CJD) is described in a 78‐year‐old woman homozygous for methionine at codon 129 of the prion protein (PrP) gene. The neuropathological signature was the presence of PrP immunoreactive plaque‐like deposits in the cerebral cortex, striatum and thalamus. Western blot analysis showed a profile of the pathological form of PrP (PrPSc) previously unrecognised in sporadic CJD, marked by the absence of diglycosylated protease resistant species. These features define a novel neuropathological and molecular CJD phenotype.

Polyanion induced fibril growth enables the development of a reproducible assay in solution for the screening of fibril interfering compounds, and the investigation of the prion nucleation site.

Abstract: The misfolded conformer of the prion protein (PrP) that aggregates into fibrils is believed to be the pathogenic agent in transmissible spongiform encephalopathies. In order to find fibril interfering compounds a screening assay in solution would be the preferred format to approximate more closely to physical conditions and enable the performance of kinetic studies. However, such an assay is hampered by the high irreproducibility because of the stochastic nature of the fibril formation process. According to published fibril models, the fibrillar core may be composed of stacked parallel β-strands. In these models positive charge repulsion may reduce the chance of favorable stacking and cause the irreproducibility in the fibril formation. This study shows that the charge compensation by polyanions induced a very strong fibril growth which made it possible to develop a highly reproducible fibril interference assay. The stimulating effect of the polyanions depended on the presence of the basic residues Lys106...