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J Collinge

Publications and source records attributed to J Collinge.

At least 19 recordsLinked to original sources
PubMed1999

Variant Creutzfeldt-Jakob disease.

It is clear that the prion strain causing bovine spongiform encephalopathy (BSE) in cattle has infected human beings, manifesting itself as a novel human prion disease, variant Creutzfeldt-Jakob disease (CjD). Studies of the incubation periods seen in previous epidemics of human prion disease and of the effect of transmission barriers limiting spread of these diseases between species, suggest that the early variant CJD cases may have been exposed during the preclinical phase of the BSE epidemic. It must therefore be considered that many cases may follow from later exposure in an epidemic that would be expected to evolve over decades. Since the number of people currently incubating this disease is unknown, there are concerns that prions might be transmitted iatrogenically via blood transfusion, tissue donation, and, since prions resist routine sterilisation, contamination of surgical instruments. Such risks remain unquantified. Although variant CJD can be diagnosed during life by tonsil biopsy, a prion-specific blood test is needed to assess and manage this potential threat to public health. The theoretical possibility that BSE prions might have transferred to other species and continue to present a risk to human health cannot be excluded at present.

Animals↗
PubMed1999

Multiple folding pathways for heterologously expressed human prion protein.

Human PrP (residues 91-231) expressed in Escherichia coli can adopt several conformations in solution depending on pH, redox conditions and denaturant concentration. Oxidised PrP at neutral pH, with the disulphide bond intact, is a soluble monomer which contains 47% alpha-helix and corresponds to PrPC. Denaturation studies show that this structure has a relatively small, solvent-excluded core and unfolds to an unstructured state in a single, co-operative transition with a DeltaG for folding of -5.6 kcal mol-1. The unfolding behaviour is sensitive to pH and at 4.0 or below the molecule unfolds via a stable folding intermediate. This equilibrium intermediate has a reduced helical content and aggregates over several hours. When the disulphide bond is reduced the protein adopts different conformations depending upon pH. At neutral pH or above, the reduced protein has an alpha-helical fold, which is identical to that observed for the oxidised protein. At pH 4 or below, the conformation rearranges to a fold that contains a high proportion of beta-sheet structure. In the reduced state the alpha- and beta-forms are slowly inter-convertible whereas when oxidised the protein can only adopt an alpha-conformation in free solution. The data we present here shows that the human prion protein can exist in multiple conformations some of which are known to be capable of forming fibrils. The precise conformation that human PrP adopts and the pathways for unfolding are dependent upon solvent conditions. The conditions we examined are within the range that a protein may encounter in sub-cellular compartments and may have implications for the mechanism of conversion of PrPC to PrPSc in vivo. Since the conversion of PrPC to PrPSc is accompanied by a switch in secondary structure from alpha to beta, this system provides a useful model for studying major structural rearrangements in the prion protein.

Circular Dichroism↗
PubMed1999

Reversible conversion of monomeric human prion protein between native and fibrilogenic conformations.

Prion propagation involves the conversion of cellular prion protein (PrPC) into a disease-specific isomer, PrPSc, shifting from a predominantly alpha-helical to beta-sheet structure. Here, conditions were established in which recombinant human PrP could switch between the native alpha conformation, characteristic of PrPC, and a compact, highly soluble, monomeric form rich in beta structure. The soluble beta form (beta-PrP) exhibited partial resistance to proteinase K digestion, characteristic of PrPSc, and was a direct precursor of fibrillar structures closely similar to those isolated from diseased brains. The conversion of PrPC to beta-PrP in suitable cellular compartments, and its subsequent stabilization by intermolecular association, provide a molecular mechanism for prion propagation.

Circular Dichroism↗
PubMed1999

Investigation of variant Creutzfeldt-Jakob disease and other human prion diseases with tonsil biopsy samples.

BACKGROUND: Prion diseases are associated with the accumulation of an abnormal isoform of cellular prion protein (PrPSc), which is the principal constituent of prions. Prions replicate in lymphoreticular tissues before neuroinvasion, suggesting that lymphoreticular biopsy samples may allow early diagnosis by detection of PrPSc. Variant Creutzfeldt-Jakob disease (variant CJD) is difficult to distinguish from common psychiatric disorders in its early stages and definitive diagnosis has relied on neuropathology. We studied lymphoreticular tissues from a necropsy series and assessed tonsillar biopsy samples as a diagnostic investigation for human prion disease. METHODS: Lymphoreticular tissues (68 tonsils, 64 spleens, and 40 lymph nodes) were obtained at necropsy from patients affected by prion disease and from neurological and normal controls. Tonsil biopsy sampling was done on 20 patients with suspected prion disease. Tissues were analysed by western blot to detect and type PrPSc, by PrP immunohistochemistry, or both. FINDINGS: All lymphoreticular tissues obtained at necropsy from patients with neuropathologically confirmed variant CJD, but not from patients with other prion diseases or controls, were positive for PrPSc. In addition, PrPSc typing revealed a consistent pattern (designated type 4t) different from that seen in variant CJD brain (type 4) or in brain from other CJD subtypes (types 1-3). Tonsil biopsy tissue was positive in all eight patients with an adequate biopsy sample and whose subsequent course has confirmed, or is highly consistent with, a diagnosis of variant CJD and negative in all patients subsequently confirmed to have other diagnoses. INTERPRETATION: We found that if, in the appropriate clinical context, a tonsil biopsy sample was positive for PrPSc, variant CJD could be diagnosed, which obviates the need for a brain biopsy sample to be taken. Our results also show that variant CJD has a different pathogenesis to sporadic CJD.

Adolescent↗
PubMed1999

Pathogenic presenilin 1 mutations (P436S & I143F) in early-onset Alzheimer's disease in the UK. Mutations in brief no. 223. Online.

Familial Alzheimer's disease (AD) is an autosomal dominant disorder characterized by memory impairment and multiple cognitive deficits which occurs in mid to late life. Early onset AD has been associated with mutations in three genes, of which presenilin 1 (PS1) mutations are the most frequent. We sequenced the open reading frame from genomic DNA of a series of 21 early onset AD (AD3) UK families in which there were at least two affected individuals in two or more generations with a diagnosis of probable or definite AD. We found PS1 mutations in six of these families with no sequence variation in the remaining 15. The six families contained between them five different mutations of which two, I143F and P436S, have not been found elsewhere. I143F shows incomplete penetration within the affected family. P436S is the most carboxy-terminal presenilin 1 mutation reported to date.

Alzheimer Disease↗
PubMed1999

Molecular biology of prion propagation.

The occurrence of new variant Creutzfeldt-Jakob disease and the experimental confirmation that it is caused by the same prion strain as BSE has dramatically highlighted the need for a precise understanding of the molecular basis of prion propagation. The molecular basis of prion-strain diversity, previously a major challenge to the protein-only model, is now becoming clearer. The conformational change thought to be central to prion propagation, from a predominantly alpha-helical fold to one predominantly comprising beta-structure, can now be reproduced in vitro, and the ability of beta-PrP to form fibrillar aggregates provides a plausible molecular mechanism for prion propagation. These and other advances in the fundamental biology of prion propagation are leading to prion diseases becoming arguably the best understood of the neurodegenerative conditions and strategies for the development of rational therapeutics are becoming clearer.

Animals↗
PubMed1999

Structural mobility of the human prion protein probed by backbone hydrogen exchange.

Prions, the causative agents of Creutzfeldt-Jacob Disease (CJD) in humans and bovine spongiform encephalopathy (BSE) and scrapie in animals, are principally composed of PrPSc, a conformational isomer of cellular prion protein (PrPC). The propensity of PrPC to adopt alternative folds suggests that there may be an unusually high proportion of alternative conformations in dynamic equilibrium with the native state. However, the rates of hydrogen/deuterium exchange demonstrate that the conformation of human PrPC is not abnormally plastic. The stable core of PrPC has extensive contributions from all three alpha-helices and shows protection factors equal to the equilibrium constant for the major unfolding transition. A residual, hyper-stable region is retained upon unfolding, and exchange analysis identifies this as a small nucleus of approximately 10 residues around the disulfide bond. These results show that the most likely route for the conversion of PrPC to PrPSc is through a highly unfolded state that retains, at most, only this small nucleus of structure, rather than through a highly organized folding intermediate.

Circular Dichroism↗
PubMed1999

Fatal familial insomnia: a new Austrian family.

We present clinical, pathological and molecular features of the first Austrian family with fatal familial insomnia. Detailed clinical data are available in five patients and autopsy in four patients. Age at onset of disease ranged between 20 and 60 years, and disease duration between 8 and 20 months. Severe loss of weight was an early symptom in all five patients. Four patients developed insomnia and/or autonomic dysfunction, and all five patients developed motor abnormalities. Analysis of the prion protein (PrP) gene revealed the codon 178 point mutation and methionine homozygosity at position 129. In all brains, neuropathology showed widespread cortical astrogliosis, widespread brainstem nuclei and tract degeneration, and olivary 'pseudohypertrophy' with vacuolated neurons, in addition to neuropathological features described previously, such as thalamic and olivary degeneration. Western blotting of one brain and immunocytochemistry in four brains revealed quantitative and regional dissociation between PrP(res)(the protease resistant form of PrP) deposition and histopathology. In the cerebellar cortex of one patient, PrP(res) deposits were prominent in the molecular layer and displayed a peculiar patchy and strip-like pattern with perpendicular orientation to the surface. In another patient, a single vacuolated neuron in the inferior olivary nuclei contained prominent intravacuolar granular PrP(res) deposits, resembling changes of brainstem neurons in bovine spongiform encephalopathy.

Adult↗
PubMed1999

Protease-resistant prion protein produced in vitro lacks detectable infectivity.

The 'protein-only' hypothesis of prion propagation argues that infectious prions consist of PrP(Sc), a conformational isomer of host-derived prion protein (PrP(C)), which can be distinguished from PrP(C) by its partial resistance to proteases. While protease-resistant PrP has been produced by mixing PrP(Sc) and recombinant-derived PrP(C) in vitro, bioassay of any new infectivity has been precluded by the need to use a large molar excess of same species PrP(Sc). Transgenic mice expressing a chimaeric hamster-mouse PrPC (MH2M PrP(C)) are, unlike conventional mice, highly susceptible to Sc237 hamster scrapie. In addition, they produce MH2M PrP(Sc) and infectivity which is pathogenic for conventional mice. We have therefore attempted to produce MH2M PrP(Sc) in vitro as any infectivity produced could be distinguished from the hamster PrP(Sc) used to promote the conversion by bioassay in conventional mice. Although protease-resistant MH2M PrP was produced, no infectivity was detected on bioassay. These results argue that acquisition of protease resistance by PrP(C) is not sufficient for the propagation of infectivity.

Animals↗
PubMed1999

Molecular genetic characterisation of frontotemporal dementia on chromosome 3.

We have previously localized a locus causing familial nonspecific dementia to the centromeric region of chromosome 3 in a pedigree from the Jutland area of Denmark. This pedigree shows anticipation. Here we present further analysis of these anticipation data which are suggestive of trinucleotide repeat expansion involvement. We also outline our strategies to clone the mutant gene via its putative associated trinucleotide repeat sequence.

Adult↗
PubMed1998

Molecular screening of sheep for bovine spongiform encephalopathy.

Bovine spongiform encephalopathy (BSE) may have transmitted to sheep through feed and pose a risk to human health. Sheep BSE cannot be clinically distinguished from scrapie, and conventional strain typing would be impractical on a significant scale. As human prion strains can be distinguished by differences in prion protein (PrPsc) conformation and glycosylation we have applied PrP(Sc) typing to sheep. We found multiple Western blot patterns of PrP(Sc) in scrapie, consistent with the known scrapie strain diversity in sheep. Sheep passaged BSE showed a PrP(Sc) banding pattern similar to BSE passaged in other species [Collinge, J., Sidle, K.C.L., Meads, J., Ironside, J. and Hill, A.F., Nature, 383 (1996) 685-690], both in terms of fragment size following proteinase K cleavage and abundance of diglycosylated PrP. However, none of the historical or contemporary scrapie cases studied had a PrP(Sc) type identical to sheep BSE. While more extensive studies, including sheep of all PrP genotypes, will be required to fully evaluate these findings, these results suggest that large scale screening of sheep for BSE may be possible.

Animals↗
PubMed1998

Prions and the prion disorders.

One of us remembers sitting in a high school biology class in 1977 being taught about scrapie, a naturally occurring disorder of sheep. The teacher had no particular interest in agriculture, but was pointing out some peculiar characteristics of this disease as a biological curiosity on a wet Friday afternoon. The prion disorders captured the imagination of a range of biologists (including that teacher) well before the epidemic of bovine spongiform encephalopathy (BSE) and the appearance of a new variant of the human prion disease, Creutzfeldt Jakob disease (CJD), in the UK, because of their extraordinary biology and the unique properties of the infectious agent. We review the results of studies leading to a convergence of evidence that the causative infectious agent, the 'prion', is devoid of nucleic acid and is composed of an abnormal isoform of a host-encoded protein, the prion protein (PrP).

Animals↗
PubMed1998

Chromosome 14 familial Alzheimer's disease: the clinical and neuropathological characteristics of a family with a leucine-->serine (L250S) substitution at codon 250 of the presenilin 1 gene.

BACKGROUND: Seven affected members are described from a kindred with autosomal dominant familial Alzheimer's disease associated with a novel mutation in the presenilin 1 (PS1) gene on chromosome 14 that results in a leucine to serine substitution at codon 250 (L250S). METHOD: Clinical information on the pedigree was collected directly from family members including affected members and their carers and also from hospital records. RESULTS: Detailed clinical information was available on five members. All had an early age at onset with a median age of 52 (95% confidence interval (95% CI) 49.4-54.9). Age at onset varied between 49 and 56 years, with duration of illness varying between six years and 15 years. Myoclonus, depression, and psychosis were features of this pedigree; seizures were not reported. CONCLUSIONS: PS1 L250S familial Alzheimer's disease is an early onset form of Alzheimer's disease with clinical features similar to other reported familial Alzheimer's disease pedigrees, except that seizures were absent.

Age of Onset↗
PubMed1998

An antibody raised against a conserved sequence of the prion protein recognizes pathological isoforms in human and animal prion diseases, including Creutzfeldt-Jakob disease and bovine spongiform encephalopathy.

Antibodies to the prion protein (PrP) have been critical to the neuropathological and biochemical characterization of PrP-related degenerative diseases in humans and animals. Although PrP is highly conserved evolutionarily, there is some sequence divergence among species; as a consequence, anti-PrP antibodies have a wide spectrum of reactivity (from strong immunopositivity to lack of reactivity) when challenged with PrP from diverse species. We have produced an antibody (anti-PrP95-108) raised against a synthetic peptide corresponding to residues 95 to 108 of human PrP and have characterized it by epitope mapping, Western immunoblot analysis, and immunohistochemistry. The antibody recognizes not only human PrP isoforms but also pathological PrP from all species tested (ie, cattle, sheep, hamsters, and mice). This is probably due to the fact that the epitope recognized by this antibody includes residues 100 to 108 of human PrP, a sequence that is also present in PrP of several other species. Thus, this reagent is valuable not only for the study of human prion diseases but also for analysis of the possible relationship between human and animal disorders.

Amino Acid Sequence↗