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At least 19 recordsLinked to original sources
PubMed1991

Secondary structure analysis of the scrapie-associated protein PrP 27-30 in water by infrared spectroscopy.

A protease-resistant form of the protein PrP (PrP-res) accumulates in tissues of mammals infected with scrapie, Creutzfeldt-Jakob disease, and related transmissible neurodegenerative diseases. This abnormal form of PrP can aggregate into insoluble amyloid-like fibrils and plaques and has been identified as the major component of brain fractions enriched for scrapie infectivity. Using a recently developed technique in Fourier transform infrared spectroscopy which allows protein conformational analysis in aqueous media, we have studied the secondary structure of the proteinase K resistant core of PrP-res (PrP-res 27-30) as it exists in highly infectious fibril preparations. Second-derivative analysis of the infrared spectra has enabled us to quantitate the relative amounts of different secondary structures in the PrP-res aggregates. The analysis indicated that PrP-res 27-30 is predominantly composed of beta-sheet (47%), which is consistent with its amyloid-like properties. In addition, significant amounts of turn (31%) and alpha-helix (17%) were identified, indicating that amyloid-like fibrils need not be exclusively beta-sheet. The infrared-based secondary structure compositions were then used as constraints to improve the theoretical localization of the secondary structures within PrP-res 27-30.

Acetylglucosamine↗
PubMed1991

Amyloid protein of Gerstmann-Sträussler-Scheinker disease (Indiana kindred) is an 11 kd fragment of prion protein with an N-terminal glycine at codon 58.

Gerstmann-Sträussler-Scheinker (GSS) disease is a familial neurological disorder pathologically characterized by amyloid deposition in the cerebrum and cerebellum. The GSS amyloid is immunoreactive to antisera raised against the hamster prion protein (PrP) 27-30. This is a proteinase K-resistant glycoprotein of 27-30 kd that is derived from an abnormal isoform of a neuronal glycoprotein of 33-35 kd designated PrPSc and is a molecular marker of amyloid fibrils isolated from animals with scrapie and humans with related disorders. We have purified and characterized proteins extracted from amyloid plaque cores isolated from two patients of the Indiana kindred of GSS disease. We found that the major component of GSS amyloid is an 11 kd degradation product of PrP, whose N-terminus corresponds to the glycine residue at position 58 of the amino acid sequence deduced from the human PrP cDNA. In addition, amyloid fractions contained larger PrP fragments with apparently intact N-termini and amyloid P component. These findings suggest that the disease process leads to proteolytic cleavage of PrP, generating an amyloidogenic peptide that polymerizes into insoluble fibrils. The N-terminal cleavage of PrP in GSS disease occurs at a tryptophan-glycine peptide bond identical to that cleaved by proteinase K in vitro to generate PrP 27-30 from hamster PrPSc at codon 90. Since no mutations of the structural PrP gene have been found in the Indiana family of GSS disease, it is conceivable that factors other than the primary structure of PrP play a crucial role in the process of amyloid formation and the development of clinical neurologic dysfunction.

Amino Acid Sequence↗
PubMed1992

Prion protein preamyloid and amyloid deposits in Gerstmann-Sträussler-Scheinker disease, Indiana kindred.

Gerstmann-Sträussler-Scheinker disease (GSS) is a familial neurological disorder pathologically characterized by amyloid deposition in the cerebrum and cerebellum. In GSS, the amyloid is immunoreactive to antisera raised against the prion protein (PrP) 27-30, a proteinase K-resistant peptide of 27-30 kDa that is derived by limited proteolysis from an abnormal isoform of a neuronal sialoglycoprotein of 33-35 kDa designated PrPSc. Polyclonal antibodies raised against synthetic peptides homologous to residues 15-40 (P2), 90-102 (P1), and 220-232 (P3) of the amino acid sequence deduced from hamster PrP cDNA were used to investigate immunohistochemically the distribution of PrP and PrP fragments in the brains of two patients from the Indiana kindred of GSS. Two types of anti-PrP-immunoreactive deposits were found: (i) amyloid deposits, which were exclusively labeled by anti-P1 antiserum to residues 90-102 of PrP, and (ii) preamyloid deposits, which were labeled by all anti-PrP antisera but did not exhibit the tinctorial and optical properties of amyloid. The latter appeared as diffuse immunostaining of the neuropil that targeted to areas in which amyloid deposits were most abundant. They were partially resistant to proteinase K digestion and consisted ultrastructurally of amorphous, flaky, electron-dense material. These findings substantiate our previous observation that the major amyloid component in the GSS Indiana kindred is an internal fragment of PrP and indicate that full-length abnormal isoforms of PrP and/or large PrP fragments accumulate in brain regions most affected by amyloid deposition. These findings support the view that in the GSS Indiana kindred a stepwise degradation of PrP occurs in situ in the process of amyloid fibril formation.

Aged↗
PubMed1991

Morphological and biochemical evidence that scrapie-associated fibrils are derived from aggregated amyloid-like filaments.

The membrane fraction from scrapie infected mouse brains was dissolved in saturated urea, centrifuged on a 10 to 50% glycerol gradient at 35,000 rpm for 24 h, and fractionated from the bottom of the tube into 11 fractions. PrP was detected throughout the gradient. However, the relative PrP concentrations of fractions 4 and 8 were the highest. The relative PrP concentration versus protein concentration of fractions 1 to 4 was higher than that of the other fractions. Scrapie infectivity also was detected in all fractions. Fractions 2, 3, 4, 7, and 8 produced the shortest incubation periods. Positively stained filamentous aggregates with sizes varying from about 40 x 60 nm to more than 4 microns were observed in fractions 2 and 4 by negative staining. These resembled amyloid filaments. Congo red-stained aggregates showed birefringence under polarized light. Aggregation of the filamentous aggregates was observed by incubation with anti-mouse SAF serum. Fine fibrils 10-18 nm in width were partially dissociated from the aggregates by brief exposure to the detergent Sarkosyl. These facts suggest that SAF are not products of self-assembly from subunit structures liberated from membranes by exposure to detergent, but exist as aggregates of amyloid-like filaments from which SAF are dissociated by detergent extraction.

Animals↗
PubMedDate not supplied

Relationship of protease-resistant protein, scrapie-associated fibrils and tubulofilamentous particles to the agent of spongiform encephalopathies.

Tubulofilamentous particles and scrapie-associated fibrils (SAF) are ultrastructural markers, while protease-resistant protein (PrP) is a molecular biological marker for all spongiform encephalopathies. Review of all published work has suggested that PrP molecules aggregate to form a three-dimensional SAF. Further reports have suggested that a single-stranded DNA wraps round SAF and acquires an outer protein coat to form tubulofilamentous particles. As incubation period increases in the infected animals, larger amounts of PrP molecules are committed to form SAF, interfering with the normal supply of PrP to cell membranes which become disrupted and eventually fragment, resulting in vacuoles typical of those found in spongiform encephalopathies.

Amino Acid Sequence↗
PubMedDate not supplied

Scrapie-associated tubulofilamentous particles in human Creutzfeldt-Jakob disease.

Scrapie-associated fibrils (SAF) were demonstrated by a simple negative staining method for electron microscopy from fresh and frozen brains with naturally occurring human Creutzfeldt-Jakob disease (CJD). The findings confirm that SAF occur as an internal part of a larger three-layer particle. The two outer coats of SAF can be disrupted by detergent alone or can be digested in two stages by a combination of proteolytic enzymes and subsequent treatment with DNase and mung bean nuclease. Examination of thin sections from the cerebral cortex of brains from patients with CJD revealed the presence of 26-30-nm diameter tubulofilamentous particles, identical to those previously described in natural scrapie of sheep and bovine spongiform encephalopathy and also in experimentally induced scrapie in mice and hamsters and CJD-infected mice and chimpanzees. Thus, it would appear that the particles are not contaminants passaged in experimental animals.

Adult↗
PubMed1991

Scrapie-infected spleens: analysis of infectivity, scrapie-associated fibrils, and protease-resistant proteins.

Scrapie-associated fibrils (SAF) and protease-resistant proteins (PrP) were isolated from spleens and brains of clinical animals (mice and hamsters) from three scrapie agent-host strain combinations, and their concentrations were compared with infectivity levels. The spleens of infected animals contained lower levels of infectivity, PrP, and SAF than did brains. Regardless of the route of infection, both SAF and infectivity were detected in spleen before brain. Infectivity increased in brains and spleens of 139A-infected mice before the detection and increase in SAF, suggesting that the synthesis of SAF and PrP may not be the limiting factor in agent replication. In contrast to those in ME7- and 263K-infected animals, the Western blot profiles for PrP from brain and spleen of 139A-infected mice exhibited distinct differences. Results indicate that SAF and PrP found in the spleens are both organ- and scrapie strain-specific.

Animals↗
PubMed1991

Evidence of ssDNA in tubulofilamentous particles: their relationship to scrapie-associated fibrils.

Abnormal tubulofilamentous particles were identified by electron microscopy using a simple touch negative staining technique from brains of mice infected with four strains of the scrapie agent. Treatment by three proteolytic enzymes and subsequent treatment with DNase and mung bean nuclease of grids prepared from the infected animals confirmed previous observations that the tubulofilamentous particles observed in scrapie-effected brains are complex structures. The core of the tubulofilamentous particle scrapie-associated fibrils was revealed by treatment with SDS. Treatment with proteolytic enzymes and subsequent treatment with DNase or mung bean nuclease or S1 nuclease also revealed typical and transitional stages of scrapie-associated fibrils. However, treatment with RNase A had no effect. The data suggest that nucleic acid is a single-stranded DNA protected by a protein coat.

Animals↗
PubMed1992

Hidden amyloidoses.

The pathogenesis as well as the genetic disposition to develop clinical symptoms in transmissible spongiform encephalopathies (e.g. Creutzfeldt-Jakob disease, scrapie, bovine spongiform encephalopathy) relate these diseases to classical noninfectious amyloidoses (familial amyloidotic polyneuropathy as an example) and to Alzheimer's disease. This is not obvious to the nonexpert at first glance. This communication tries to elucidate this association, to reveal which immunochemical techniques have contributed their share.

Alzheimer Disease↗
PubMed1992

Structural and functional changes of blood-brain barrier and indication of prion amyloid filaments in experimental amyotrophic leucospongiosis.

The reproduction of amyotrophic leukospongiosis (AL) agent in the central nervous system (CNS) of guinea pigs was accompanied by local disturbance of blood-brain barrier (BBB), which manifested in passing of horseradish peroxidase through the endothelium of some of capillaries (10-14%). The disturbance of BBB function coincided with dystrophic changes in a number of pericapillary astrocyte foot processes and in pericytes. In the walls of altered vessels we observed congophilic (amyloid) deposits, which formed immunocomplexes with monoclonal antibodies to the AL agent protein PrP 27-30 kD. By electron microscopic the deposits consisted of masses of filaments with diameter of 5-10 nm located between the basement membrane and endothelium of the vessels.

Amyloid↗
PubMed1992

Amphotericin B treatment dissociates in vivo replication of the scrapie agent from PrP accumulation.

Scrapie and related animal and human disorders are neurodegenerative diseases characterized by the formation of a modified, partly proteinase-resistant protein (PrP) of the host, which tends to aggregate as amyloid fibrils and accumulate in the brain of infected individuals. There is a general consensus that the pathological form of PrP (PrPSc) is essential for the clinical appearance of the disease, but whether it is part of the scrapie agent or a by-product of viral infection is still controversial. Here we report that treatment of scrapie-infected hamsters with amphotericin B delays the accumulation in the brain of the proteinase-resistant portion of PrPSc by about 30 days without affecting scrapie replication. The consequence is that hamsters treated with amphotericin B developed clinical signs of disease later than infected controls. We argue that the proteinase-resistant portion of PrPSc is necessary for the development of the disease but that it is unlikely to be essential for scrapie replication.

Amphotericin B↗
PubMed1991

Molecular biology and transgenetics of prion diseases.

Considerable progress has been made deciphering the role of an abnormal isoform of the prion protein (PrP) in scrapie of animals and Gerstmann-Sträussler syndrome (GSS) of humans. Some transgenic (Tg) mouse (Mo) lines that carry and express a Syrian hamster (Ha) PrP gene developed scrapie 75 d after inoculation with Ha prions; non-Tg mice failed to show symptoms after greater than 500 d. Brains of these infected Tg(HaPrP) mice featured protease-resistant HaPrPSc, amyloid plaques characteristic for Ha scrapie, and 10(9) ID50 units of Ha-specific prions upon bioassay. Studies on Syrian, Armenian, and Chinese hamsters suggest that the domain of the PrP molecule between codons 100 and 120 controls both the length of the incubation time and the deposition of PrP in amyloid plaques. Ataxic GSS in families shows genetic linkage to a mutation in the PrP gene, leading to the substitution of Leu for Pro at codon 102. Discovery of a point mutation in the Prp gene from humans with GSS established that GSS is unique among human diseases--it is both genetic and infectious. These results have revised thinking about sporadic Creutzfeldt-Jakob disease, suggesting it may arise from a somatic mutation. These findings combined with those from many other studies assert that PrPSc is a component of the transmissible particle, and the PrP amino acid sequence controls the neuropathology and species specificity of prion infectivity. The precise mechanism of PrPSc formation remains to be established. Attempts to demonstrate a scrapie-specific nucleic acid within highly purified preparations of prions have been unrewarding to date. Whether transmissible prions are composed only of PrPSc molecules or do they also contain a second component such as small polynucleotide remains uncertain.

Alzheimer Disease↗
PubMed1991

Immunolocalization of scrapie amyloid (PrP27-30) in chronic wasting disease of Rocky Mountain elk and hybrids of captive mule deer and white-tailed deer.

Scrapie amyloid-immunoreactive plaques are present in brain tissues of captive mule deer with chronic wasting disease (CWD), a progressive neurological disorder characterized neuropathologically by widespread spongiform change of the neuropil, intracytoplasmic vacuolation in neuronal perikarya and astrocytic hypertrophy and hyperplasia. We report here the immunolocalization of scrapie amyloid (PrP27-30) in plaques observed in brain tissues of Rocky Mountain elk (Cervus elaphus nelsoni) and hybrids of mule deer and white-tailed deer (Odocoileus virginianus) naturally affected with CWD. Similar findings have been shown in kuru, Creutzfeldt-Jakob disease, and Gerstmann-Sträussler syndrome in humans. Our data corroborate that CWD in Rocky Mountain elk and hybrids of mule deer and white-tailed deer belongs to the subacute spongiform virus encephalopathies (transmissible cerebral amyloidoses).

Animals↗