New haplotype of familial Creutzfeldt-Jakob disease with a codon 200 mutation and a codon 219 polymorphism of the prion protein gene in a Japanese family

A systemic analysis of Creutzfeldt Jakob disease cases in Asia

Creutzfeldt Jakob Disease (CJD) is a rapidly progressive, fatal neurodegenerative disorder, also known as a subacute spongiform encephalopathy. There are three major subtypes of CJD i.e. Sporadic CJD, which occurs for reasons unbeknown to science (85% of known cases), Genetic or Familial CJD which is characterized by the presence of mutations in the human prion protein (PRNP) gene (10-15% cases) and Iatrogenic CJD that occurs via accidental transmission through medical and surgical procedures (1-2% cases). CJD cases occur globally with 1 case per one million population/year. Considerable data is available related to the incidence and prevalence of CJD in Europe and America. However, the global surveillance database is yet to include Asia even though several Asian countries have their own CJD monitoring units. sCJD is the highest among all CJD cases in Asia. China (1957) and Japan (1705) have reported more cases of sCJD than any Asian country and Hong Kong (1) has reported the least. On the other hand, gCJD is highest in Japan (370) and least in India (2). Our analysis establishes the presence of all variants of CJD across Asia. However, in most Asian countries in general and Southeast Asian countries in particular, CJD cases are misdiagnosed and often underreported. Since Asia is the most populated continent in the world, the actual global prevalence of CJD cannot be estimated until and unless these countries are accounted for. Concrete and reliable surveillance networks are needed across Asia to evaluate the prevalence and incidence of CJD in the region. [Figure: see text]The graphical abstract demonstrates the prevalence of CJD cases in the world and systematically analyses the incidence of CJD in Asian countries between the year 1986-2022. Highest number of cases were reported in Japan followed by China. The study emphasizes the need for assimilation of Asian data in global prevalence.

Quantifying the Role of Lysine in Prion Replication by Nano-LC Mass Spectrometry and Bioassay

Prions propagate by a template driven process, inducing the normal cellular isoform (PrP^C) to adopt the prion (PrP^Sc) conformation. In PrP^C, the positions of lysines are highly conserved and strongly influence prion propagation. In this study, covalent modification was used to quantitate the role of lysines in the PrP^Sc template that drives prion replication. The ε-amino group of lysines in the PrP^Sc (hamster-adapted scrapie Sc237) template was acetylated by either acetic anhydride (Ac₂O) or the N-hydroxysuccinimide ester of acetic acid (Ac-NHS). The extent of lysine acetylation in PrP^Sc was quantitated by mass spectrometry or Western blot-based analysis. Identical samples were bioassayed to quantitate the loss of infectivity associated with lysine acetylation. The reduction of infectivity at the highest reagent concentration was approximately 90% (∼10-fold). Ten of the eleven prion lysines were acetylated to a greater extent (25−400-fold) than the observed loss of infectivity. Only one lysine, at position 220 (K₂₂₀), had a reactivity that is consistent with the loss of infectivity. Although lysines are highly conserved and play a crucial role in converting PrP^C into the PrP^Sc conformation, once that conformation is adopted, the lysines present in the PrP^Sc template play only a limited role in prion replication. In principle, this approach could be used to clarify the role of other amino acids in the replication of prions and other prion-like protein misfolding diseases.

[Genetic Creutzfeldt-Jakob disease with a glutamate-to-lysine substitution at codon 219 (E219K) in the presence of the E200K mutation presenting with rapid progressive dementia following slowly progressive clinical course]

A 57-year-old man developed rapidly progressive dementia and a gait disturbance over 4 months. The patient had a slowly progressive executive dysfunction and speech problems for 4 years and was previously monitored in our outpatient clinic following a diagnosis of frontotemporal dementia. Diffusion-weighted MRI revealed high signal intensities in the right caudate nucleus and the bilateral cortices. Cerebrospinal fluid analysis showed increased levels of the 14-3-3 and total tau proteins. Periodic synchronous discharge was not evident on an electroencephalogram. Prion protein gene analysis identified a glutamate-to-lysine substitution at codon 219 (E219K) in the presence of the E200K mutation, leading to a genetic diagnosis of genetic Creutzfeldt-Jakob disease (CJD). The E219K polymorphism found on the allele of the E200K mutation may have influenced the characteristic clinical course of our patient that differed from that of typical E200K genetic CJD.

Structural basis for the complete resistance of the human prion protein mutant G127V to prion disease

Prion diseases are caused by the propagation of misfolded cellular prion proteins (PrPs). A completely prion disease-resistant genotype, V127M129, has been identified in Papua New Guinea and verified in transgenic mice. To disclose the structural basis of the disease-resistant effect of the G127V mutant, we determined and compared the structural and dynamic features of the G127V-mutated human PrP (residues 91-231) and the wild-type PrP in solution. HuPrP(G127V) contains α1, α2 and α3 helices and a stretch-strand (SS) pattern comprising residues Tyr128-Gly131 (SS1) and Val161-Arg164 (SS2), with extending atomic distances between the SS1 and SS2 strands, and a structural rearrangement of the Tyr128 side chain due to steric hindrance of the larger hydrophobic side chain of Val127. The extended α1 helix gets closer to the α2 and α3 helices. NMR dynamics analysis revealed that Tyr128, Gly131 and Tyr163 underwent significant conformational exchanges. Molecular dynamics simulations suggest that HuPrP(G127V) prevents the formation of stable β-sheets and dimers. Unique structural and dynamic features potentially inhibit the conformational conversion of the G127V mutant. This work is beneficial for understanding the molecular mechanisms underlying the complete resistance of the G127V mutant to prion disease and for developing new therapeutics for prion disease.

Disulfide-crosslink scanning reveals prion-induced conformational changes and prion strain-specific structures of the pathological prion protein PrPSc

Prions are composed solely of the pathological isoform (PrP^Sc) of the normal cellular prion protein (PrP^C). Identification of different PrP^Sc structures is crucially important for understanding prion biology because the pathogenic properties of prions are hypothesized to be encoded in the structures of PrP^Sc However, these structures remain yet to be identified, because of the incompatibility of PrP^Sc with conventional high-resolution structural analysis methods. Previously, we reported that the region between the first and the second α-helix (H1∼H2) of PrP^C might cooperate with the more C-terminal side region for efficient interactions with PrP^Sc From this starting point, we created a series of PrP variants with two cysteine substitutions (C;C-PrP) forming a disulfide-crosslink between H1∼H2 and the distal region of the third helix (Ctrm). We then assessed the conversion capabilities of the C;C-PrP variants in N2a cells infected with mouse-adapted scrapie prions (22L-ScN2a). Specifically, Cys substitutions at residues 165, 166, or 168 in H1∼H2 were combined with cysteine scanning along Ctrm residues 220-229. We found that C;C-PrPs are expressed normally with glycosylation patterns and subcellular localization similar to WT PrP, albeit differing in expression levels. Interestingly, some C;C-PrPs converted to protease-resistant isoforms in the 22L-ScN2a cells, but not in Fukuoka1 prion-infected cells. Crosslink patterns of convertible C;C-PrPs indicated a positional change of H1∼H2 toward Ctrm in PrP^Sc-induced conformational conversion. Given the properties of the C;C-PrPs reported here, we propose that these PrP variants may be useful tools for investigating prion strain-specific structures and structure-phenotype relationships of PrP^Sc.

Probing early misfolding events in prion protein mutants by NMR spectroscopy

The post-translational conversion of the ubiquitously expressed cellular form of the prion protein, PrPC, into its misfolded and pathogenic isoform, known as prion or PrPSc, plays a key role in prion diseases. These maladies are denoted transmissible spongiform encephalopathies (TSEs) and affect both humans and animals. A prerequisite for understanding TSEs is unraveling the molecular mechanism leading to the conversion process whereby most α-helical motifs are replaced by β-sheet secondary structures. Importantly, most point mutations linked to inherited prion diseases are clustered in the C-terminal domain region of PrPC and cause spontaneous conversion to PrPSc. Structural studies with PrP variants promise new clues regarding the proposed conversion mechanism and may help identify "hot spots" in PrPC involved in the pathogenic conversion. These investigations may also shed light on the early structural rearrangements occurring in some PrPC epitopes thought to be involved in modulating prion susceptibility. Here we present a detailed overview of our solution-state NMR studies on human prion protein carrying different pathological point mutations and the implications that such findings may have for the future of prion research.

Codon 200 mutation of the prion gene: genotype-phenotype correlations

Genetic mutations as a cause of prion diseases are rare. We describe a large family with multiple affected members with the codon E200K prion mutation. To improve understanding of the genotype-phenotype correlations of prion gene mutations, clinical, genetic and neuropathological data were obtained from family members over 15 years. Six patients with the codon E200K mutation and 2 patients without the codon 200 mutation from this family were followed. The 6 patients with the codon 200 mutation had a mean age onset of 58.83 years (SD 7.2; lower 95 % CI 51.0; upper 95 % CI 66.4). The most common symptoms at onset were memory loss, walking difficulties and hallucinations. The most frequent neurological phenomena were a rapidly progressive dementia, eye movement abnormalities and ataxia. The mean duration of onset of symptoms to death was 3.9 months (SD 1.1; lower 95 % CI 2.8; upper 95 % CI 5.1). Two male patients developed neurodegenerative disorders unrelated to the prion codon 200 mutation: progressive supranuclear palsy and olivopontocerebellar degeneration. Their mean survival was 96 months (SD 33.9; p < 0.0001). Individuals from families with the prion codon 200 mutation may have a rapidly progressive dementia. Members of families with inherited prion mutations may be at risk of other neurodegenerative disorders unrelated to the prion mutation.

Unique clinicopathological features and PrP profiles in the first autopsied case of dura mater graft-associated Creutzfeldt-Jakob disease with codon 219 lysine allele observed in Japanese population

Polymorphism at codon 219 lysine in prion protein (PrP) is considered to affect the clinicopathological features of prion diseases including Creutzfeldt-Jakob disease (CJD) and to have an inhibiting effect on the pathogenesis of these diseases. We describe the first autopsied case of dura mater graft-associated CJD (dCJD) with heterozygosity of lysine at codon 219 in PrP observed in a Japanese subject. Although this case demonstrated the non-plaque type of dCJD and MM1 subgroup of CJD pathologically and biochemically, the patient demonstrated a long incubation period (19.3 years), atypical periodic sharp-wave complexes with a dominant rhythm on EEG, partially scattered small deposits of plaque-like PrP along with synaptic type deposits of PrP on immunohistochemistry and an atypical MM1 glycosylation pattern with a relatively increased diglycosylated isoform of proteinase-resistant PrP on western blot analysis (i.e. "MM1 variant" pattern). These findings in this case were atypical of the non-plaque type of dCJD and MM1 subgroup of CJD. Thus, these findings can be unique to dCJD with codon 219 lysine allele, and this allele may influence the clinicopathological features and PrP profiles in dCJD.

Panencephalopathic Creutzfeldt-Jakob disease in the Netherlands and the UK: clinical and pathological characteristics of nine patients

AIMS

The panencephalopathic type of Creutzfeldt-Jakob disease (PECJD) has extensive abnormalities in cerebral white matter as well as the cortex. PECJD has rarely been described in Caucasians and debate continues on its classification and pathogenesis. We describe our experience of PECJD over a 14-year period of surveillance for CJD in the Netherlands and the UK.

METHODS

Between 1993 and 2006, nine cases of PECJD were identified. Clinical, histological and biochemical characteristics of all patients were analysed and compared; all cases were classified clinically as sporadic CJD.

RESULTS

The median age at onset was 57.8 years and median disease duration was 22 months. The average brain weight was 887 g. Most patients showed a two-stage clinical course with initial rapid deterioration to a state of akinetic mutism, which then persisted over a longer time scale. Neuropathological findings were characterized by severe global atrophy with status spongiosus. Cerebral white matter involvement tended to be associated with either disease duration or severity of cerebral cortical lesions. Five patients could be classified into the MM1 subtype of sporadic CJD, one patient into the MM2 subgroup and another into the MV2 subgroup. Two patients were heterozygous at codon 129 in the prion protein gene and contained both type 1 and type 2 PrP(res) isoforms in the brain.

CONCLUSIONS

We believe that white matter pathology in PECJD represents an end-stage pattern that reflects secondary degeneration due to widespread cortical neuronal loss that occurs in the early part of the disease, rather than representing a primary lesion.

Prion disease genetics

Prion diseases have stimulated intense scientific scrutiny since it was proposed that the infectious agent was devoid of nucleic acid. Despite this finding, genetics has played a key role in understanding the pathobiology and clinical aspects of prion disease through the effects of a series of polymorphisms and mutations in the prion protein gene (PRNP). The advent of variant Creutzfeldt-Jakob disease has confirmed one of the most powerful human genetic susceptibility factors, as all tested patients have an identical genotype at polymorphic codon 129 of PRNP. This review will also consider the accrued reports of inherited prion disease and attempt a genotype-phenotype correlation. The prospects for detection of novel genetic susceptibility factors using mouse models and human genetic association studies will be explored.

Identification of an allelic variant of the goat PrP gene associated with resistance to scrapie

The association between PrP gene variations and scrapie susceptibility was studied in a single herd of Ionica breed goats. The entire herd comprised 100 animals, 11 of which were clinically affected and showed pathological prion protein (PrPSc) deposition in both their central nervous system (CNS) and lymphoreticular system (LRS). Among asymptomatic goats, nine harboured PrPSc in both CNS and LRS, 19 showed PrPSc only at the LRS level and 61 animals had no PrPSc deposition. Genetic analysis of the PrP gene coding sequence revealed the presence of several polymorphisms, namely G37V, T110P, H143R, R154H, Q222K and P240S. Silent polymorphisms were also found at codons 42, 138, 219 and 232. The effect of PrP polymorphism on scrapie susceptibility was assessed by comparing the genotype distribution at each locus among animals with different pathogenetic and clinical disease stages. Significant differences in the distribution of genotypes were observed for codons 154 and 222, with polymorphism at codon 154 modulating susceptibility to scrapie and lysine at codon 222 being associated with scrapie resistance. The allelic variant encoding lysine at position 222 could be a valuable candidate to select in the framework of appropriate breeding programmes for scrapie resistance in goats.

Diffusion-weighted MRI in familial Creutzfeldt–Jakob disease with the codon 200 mutation in the prion protein gene

Magnetic resonance imaging (MRI) with diffusion-weighted imaging (DWI) has been reported to be a useful tool for early diagnosis of sporadic Creutzfeldt-Jakob disease (CJD). We report MRI findings with DWI, as well as with fluid-attenuated inversion recovery (FLAIR) and T1-weighted imaging (T1WI), in a case of familial CJD with a mutation at codon 200 of the prion protein gene. DWI in this patient showed high signal intensity in the basal ganglia and the cerebral cortex, similar to findings in sporadic CJD. In addition, T1WI showed areas of high signal intensity bilaterally in the globus pallidus. Despite the clinical diversity and atypical laboratory findings seen in familial CJD with the codon 200 mutation, these neuroimaging studies suggest that common regional distributions and a common pathogenesis might underlie the clinical progression both in sporadic CJD and in familial CJD with the codon 200 mutation in the prion protein gene. DWI abnormalities may be characteristic features that should be considered in the diagnosis of familial as well as of sporadic CJD.

Distinctive cerebellar immunoreactivity for the prion protein in familial (E200K) Creutzfeldt-Jakob disease

We have compared the immunomorphological spectrum of the deposition of the disease-associated prion protein (PrP(Sc)) in the cerebral and cerebellar cortex of 32 Creutzfeldt-Jakob disease (CJD) patients with the PrP gene (PRNP) E200K mutation to 45 sporadic CJD and 14 other genetic prion disease cases. PrP deposits correlate with the genotype at the methionine/valine (MV) polymorphic codon 129. While the diffuse/synaptic and patchy/perivacuolar PrP deposits and PrP plaques have a similar distribution and correlation with the genotype at codon 129 as in sporadic CJD, an additional peculiar PrP immunostaining pattern occurs in the cerebellum in 81% E200K mutation brains including 93% of M129M, 71% of M129V, but not in the single V129V case. It is localized to the molecular layer and consists of coarse granular PrP deposits arranged in a stripe-like manner predominantly perpendicular to the surface, closely resembling the parasagittal arborization of climbing fibers. Our results suggest that (1) the type of PrP deposits in the cerebellum may suggest genetic disease and the need for genetic testing; and (2) the peculiar stripes of PrP deposits might reflect selective vulnerability of cerebellar structures.