Clinical and neuropathological phenotype associated with the novel V189I mutation in the prion protein gene

Understanding Creutzfeldt-Jakob disease in Iran: a systematic review of case reports

OBJECTIVE

To systematically review the reported cases of Creutzfeldt-Jakob disease (CJD) in Iran.

METHODS

A comprehensive literature review of CJD cases in Iran was undertaken using the PubMed®, Scopus® and Google Scholar databases. In addition, the Iranian database MagIran was searched for Persian language reports. Case selection used the following criteria: (i) patients of Iranian origin; (ii) publication in peer-reviewed journals or reputable medical databases; (iii) a definitive diagnosis of CJD based on established diagnostic criteria.

RESULTS

Thirteen cases from twelve reports were included in this systematic review. The majority of the cases were female (11 of 13; 84.6%). The mean ± SD age of patients at hospital admission was 59.38 ± 7.44 years. The findings of the case review suggested that the prevalence of CJD in Iran is not fully established. CJD may be misdiagnosed alongside other clinical signs. The most prevalent early indications of the disease were psychiatric and neurological in nature. A considerable delay in diagnosis was observed in some cases and there was a shortage of brain autopsy records.

CONCLUSION

Efforts to improve diagnostic capabilities, promote awareness and establish monitoring systems are necessary for managing the challenges of providing an early diagnosis of CJD in Iran.

Characterization of microtubule-associated protein tau isoforms and Alzheimer's disease-like pathology in normal sheep (Ovis aries): relevance to their potential as a model of Alzheimer's disease

Alzheimer's disease is a chronic neurodegenerative disease that accounts for up to 80% of all dementias. Characterised by deteriorations of memory and cognitive function, the key neuropathological features are accumulations of β-amyloid and hyperphosphorylated tau, as 'plaques' and 'tangles', respectively. Despite extensive study, however, the exact mechanism underlying aggregate formation in Alzheimer's disease remains elusive, as does the contribution of these aggregates to disease progression. Importantly, a recent evaluation of current Alzheimer's disease animal models suggested that rodent models are not able to fully recapitulate the pathological intricacies of the disease as it occurs in humans. Therefore, increasing attention is being paid to species that might make good alternatives to rodents for studying the molecular pathology of Alzheimer's disease. The sheep (Ovis aries) is one such species, although to date, there have been few molecular studies relating to Alzheimer's disease in sheep. Here, we investigated the Alzheimer's disease relevant histopathological characteristics of 22 sheep, using anti-β-amyloid (Abcam 12267 and mOC64) and phosphorylation specific anti-tau (AT8 and S396) antibodies. We identified numerous intraneuronal aggregates of both β-amyloid and tau that are consistent with early Alzheimer's disease-like pathology. We confirmed the expression of two 3-repeat (1N3R, 2N3R) and two 4-repeat (1N4R, 2N4R) tau isoforms in the ovine brain, which result from the alternative splicing of two tau exons. Finally, we investigated the phosphorylation status of the serine396 residue in 30 sheep, and report that the phosphorylation of this residue begins in sheep aged as young as 2 years. Together, these data show that sheep exhibit naturally occurring β-amyloid and tau pathologies, that reflect those that occur in the early stages of Alzheimer's disease. This is an important step towards the validation of the sheep as a feasible large animal species in which to model Alzheimer's disease.

A systematic review of molecular alterations in invasive non-functioning pituitary adenoma

PURPOSE

Invasive non-functional pituitary adenomas (NFPAs) constitute 35% of NFPAs. Despite a relatively large body of molecular investigations on the invasiveness of NFPA, the underlying molecular mechanisms of invasiveness are yet to be determined. Herein, we aimed to provide an overview of gene/microRNA(miRNAs) expression alterations in invasive NFPA.

METHODS

This article describes a systematic literature review of articles published up to March 23, 2021, on the transcriptional alterations of invasive NFPA. Five digital libraries were searched, and 42 articles in total fulfilled the eligibility criteria. Pathway enrichment was conducted, and protein interactions among the identified deregulated genes were inferred.

RESULTS

In total 133 gene/protein transcriptional alterations, comprising 87 increased and 46 decreased expressions, were detected in a collective number of 1001 invasive compared with 1007 non-invasive patients with NFPA. Deregulation of CDH1, PTTG1, CCNB1, SNAI1, SLUG, EZR, and PRKACB, which are associated with epidermal-mesenchymal transition (EMT), was identified. Moreover, six members of the angiogenesis pathway, i.e., VEGFA, FLT1, CCND1, CTNNB1, MYC(c-MYC), and PTTG1, were detected. SLC2A1, FLT1, and VEGFA were also recognized in the hypoxia pathway. Physical interactions of CTNNB1 with FLT1, CCND1, and EZR as well as its indirect interactions with VEGFA, MYC, CCNB1, and PCNA indicate the tight interplay between EMT, angiogenesis, and hypoxia pathways in invasive NFPAs. In addition, Hippo, JAK-STAT, MAPK, Wnt, PI3K-Akt, Ras, TGF-b, VEGF, and ErbB were identified as interwoven signaling pathways.

CONCLUSION

In conclusion, invasive NFPA shares very common deregulated signaling pathways with invasive cancers. A large amount of heterogeneity in the reported deregulations in different studies necessitates the validation of the expressional changes of the suggested biomarkers in a large number of patients with invasive NFPA.

Mapping cortical disease-burden at individual-level in frontotemporal dementia: implications for clinical care and pharmacological trials

Imaging studies of FTD typically present group-level statistics between large cohorts of genetically, molecularly or clinically stratified patients. Group-level statistics are indispensable to appraise unifying radiological traits and describe genotype-associated signatures in academic studies. However, in a clinical setting, the primary objective is the meaningful interpretation of imaging data from individual patients to assist diagnostic classification, inform prognosis, and enable the assessment of progressive changes compared to baseline scans. In an attempt to address the pragmatic demands of clinical imaging, a prospective computational neuroimaging study was undertaken in a cohort of patients across the spectrum of FTD phenotypes. Cortical changes were evaluated in a dual pipeline, using standard cortical thickness analyses and an individualised, z-score based approach to characterise subject-level disease burden. Phenotype-specific patterns of cortical atrophy were readily detected with both methodological approaches. Consistent with their clinical profiles, patients with bvFTD exhibited orbitofrontal, cingulate and dorsolateral prefrontal atrophy. Patients with ALS-FTD displayed precentral gyrus involvement, nfvPPA patients showed widespread cortical degeneration including insular and opercular regions and patients with svPPA exhibited relatively focal anterior temporal lobe atrophy. Cortical atrophy patterns were reliably detected in single individuals, and these maps were consistent with the clinical categorisation. Our preliminary data indicate that standard T1-weighted structural data from single patients may be utilised to generate maps of cortical atrophy. While the computational interpretation of single scans is challenging, it offers unrivalled insights compared to visual inspection. The quantitative evaluation of individual MRI data may aid diagnostic classification, clinical decision making, and assessing longitudinal changes.

DNA Double-Strand Breaks as Pathogenic Lesions in Neurological Disorders

The damage and repair of DNA is a continuous process required to maintain genomic integrity. DNA double-strand breaks (DSBs) are the most lethal type of DNA damage and require timely repair by dedicated machinery. DSB repair is uniquely important to nondividing, post-mitotic cells of the central nervous system (CNS). These long-lived cells must rely on the intact genome for a lifetime while maintaining high metabolic activity. When these mechanisms fail, the loss of certain neuronal populations upset delicate neural networks required for higher cognition and disrupt vital motor functions. Mammalian cells engage with several different strategies to recognize and repair chromosomal DSBs based on the cellular context and cell cycle phase, including homologous recombination (HR)/homology-directed repair (HDR), microhomology-mediated end-joining (MMEJ), and the classic non-homologous end-joining (NHEJ). In addition to these repair pathways, a growing body of evidence has emphasized the importance of DNA damage response (DDR) signaling, and the involvement of heterogeneous nuclear ribonucleoprotein (hnRNP) family proteins in the repair of neuronal DSBs, many of which are linked to age-associated neurological disorders. In this review, we describe contemporary research characterizing the mechanistic roles of these non-canonical proteins in neuronal DSB repair, as well as their contributions to the etiopathogenesis of selected common neurological diseases.

Alterations of Striatal Subregions in a Prion Protein Gene V180I Mutation Carrier Presented as Frontotemporal Dementia With Parkinsonism

Objective

To explore the roles of striatal subdivisions in the pathogenesis of frontotemporal dementia with parkinsonism (FTDP) in a patient resulting from prion protein gene (PRNP) mutation.

Methods

This patient received clinical interviews and underwent neuropsychological assessments, genetic testing, [18F]-fluorodeoxyglucose positron emission tomography ([18F]-FDG PET)/MRI, and [18F]-dihydrotetrabenazine positron emission tomography ([18F]-DTBZ PET)/CT. Region-of-interest analysis was conducted concerning metabolism, and dopamine transport function between this patient and 12 controls, focusing on the striatum subregions according to the Oxford-GSK-Imanova Striatal Connectivity Atlas.

Results

A 64-year-old man initially presented with symptoms of motor dysfunction and subsequently behavioral and personality changes. FTDP was initially suspected. Sequence analysis disclosed a valine to isoleucine at codon 180 in PRNP. Compared to controls, this patient had a severe reduction (> 2SD) of standard uptake value ratio (SUVR) in the limbic and executive subregions but relative retention of metabolism in rostral motor and caudal motor subregions using [18F]-FDG PET/MRI, and the SUVR decreased significantly across the striatal in [18F]-DTBZ PET/CT, especially in the rostral motor and caudal motor subregions.

Conclusion

The alteration of frontal striatal loops may be involved in cognitive impairment in FTDP, and the development of parkinsonism in FTDP may be primarily due to the involvement of the presynaptic nigrostriatal loops in PRNP V180I mutation.

Immunovirotherapy for Pediatric Solid Tumors: A Promising Treatment That is Becoming a Reality

Immunotherapy has seen tremendous strides in the last decade, acquiring a prominent position at the forefront of cancer treatment since it has been proven to be efficacious for a wide variety of tumors. Nevertheless, while immunotherapy has changed the paradigm of adult tumor treatment, this progress has not yet been translated to the pediatric solid tumor population. For this reason, alternative curative therapies are urgently needed for the most aggressive pediatric tumors. In recent years, oncolytic virotherapy has consolidated as a feasible strategy for cancer treatment, not only for its tumor-specific effects and safety profile but also for its capacity to trigger an antitumor immune response. This review will summarize the current status of immunovirotherapy to treat cancer, focusing on pediatric solid malignancies. We will revisit previous basic, translational, and clinical research and discuss advances in overcoming the existing barriers and limitations to translate this promising therapeutic as an every-day cancer treatment for the pediatric and young adult populations.

The interplay between oxidative stress and autophagy: focus on the development of neurological diseases

Regarding the epidemiological studies, neurological dysfunctions caused by cerebral ischemia or neurodegenerative diseases (NDDs) have been considered a pointed matter. Mount-up shreds of evidence support that both autophagy and reactive oxygen species (ROS) are involved in the commencement and progression of neurological diseases. Remarkably, oxidative stress prompted by an increase of ROS threatens cerebral integrity and improves the severity of other pathogenic agents such as mitochondrial damage in neuronal disturbances. Autophagy is anticipated as a cellular defending mode to combat cytotoxic substances and damage. The recent document proposes that the interrelation of autophagy and ROS creates a crucial function in controlling neuronal homeostasis. This review aims to overview the cross-talk among autophagy and oxidative stress and its molecular mechanisms in various neurological diseases to prepare new perceptions into a new treatment for neurological disorders. Furthermore, natural/synthetic agents entailed in modulation/regulation of this ambitious cross-talk are described.

Prion Dissemination through the Environment and Medical Practices: Facts and Risks for Human Health

Prion diseases are a group of fatal, infectious neurodegenerative disorders affecting various species of mammals, including humans. The infectious agent in these diseases, termed prion, is composed exclusively of a misfolded protein that can spread and multiply in the absence of genetic materials. In this article, we provide an overview of the mechanisms of prion replication, interindividual transmission, and dissemination in communities. In particular, we review the potential role of the natural environment in prion transmission, including the mechanisms and pathways for prion entry and accumulation in the environment as well as its roles in prion mutation, adaptation, evolution, and transmission. We also discuss the transmission of prion diseases through medical practices, scientific research, and use of biological products. Detailed knowledge of these aspects is crucial to limit the spreading of existing prion diseases as well as to prevent the emergence of new diseases with possible catastrophic consequences for public health.

Interaction of Tau construct K18 with model lipid membranes

One of the hallmarks of Alzheimer's disease (AD) is the formation of neurofibrillary tangles, resulting from the aggregation of the tubulin associated unit protein (Tau), which holds a vital role in maintaining neuron integrity in a healthy brain. The development of such aggregates and their deposition in the brain seem to correlate with the onset of neurodegeneration processes. The misfolding and subsequent aggregation of the protein into paired helical filaments that further form the tangles, lead to dysfunction of the protein with neuronal loss and cognitive decline. The aggregation of the protein then seems to be a causative factor of the neurodegeneration associated with AD. The hypothesis of an involvement of the membrane in modulating the misfolding and assembly of Tau into paired helical filaments attracts increasing interests. To provide more insight about how lipids can modulate the interactions with Tau, we have conducted a comprehensive Atomic Force Microscopy (AFM) study involving supported lipid bilayers of controlled compositions with the Tau microtubule-binding construct K18. Particularly, the effects of zwitterionic and negatively charged phospholipids on the interaction have been investigated. Deleterious solubilization effects have been evidenced on fluid zwitterionic membranes as well as an inability of K18 to fragment gel phases. The role of negative lipids in the aggregation of the peptide and the particular ability of phosphatidylinositol-4,5-bisphosphate (PIP₂) in inducing K18 fibrillization on membranes are also reported.

Astrocytic atrophy as a pathological feature of Parkinson's disease with LRRK2 mutation

The principal hallmark of Parkinson's disease (PD) is the selective neurodegeneration of dopaminergic neurones. Mounting evidence suggests that astrocytes may contribute to dopaminergic neurodegeneration through decreased homoeostatic support and deficient neuroprotection. In this study, we generated induced pluripotent stem cells (iPSC)-derived astrocytes from PD patients with LRRK2(G2019S) mutation and healthy donors of the similar age. In cell lines derived from PD patients, astrocytes were characterised by a significant decrease in S100B and GFAP-positive astrocytic profiles associated with marked decrease in astrocyte complexity. In addition, PD-derived astrocytes demonstrated aberrant mitochondrial morphology, decreased mitochondrial activity and ATP production along with an increase of glycolysis and increased production of reactive oxygen species. Taken together, our data indicate that astrocytic asthenia observed in patient-derived cultures with LRRK2(G2019S) mutation may contribute to neuronal death through decreased homoeostatic support, elevated oxidative stress and failed neuroprotection.

A seven-residue deletion in PrP leads to generation of a spontaneous prion formed from C-terminal C1 fragment of PrP

Prions result from a drastic conformational change of the host-encoded cellular prion protein (PrP), leading to the formation of β-sheet-rich, insoluble, and protease-resistant self-replicating assemblies (PrP^Sc). The cellular and molecular mechanisms involved in spontaneous prion formation in sporadic and inherited human prion diseases or equivalent animal diseases are poorly understood, in part because cell models of spontaneously forming prions are currently lacking. Here, extending studies on the role of the H2 α-helix C terminus of PrP, we found that deletion of the highly conserved ¹⁹⁰HTVTTTT¹⁹⁶ segment of ovine PrP led to spontaneous prion formation in the RK13 rabbit kidney cell model. On long-term passage, the mutant cells stably produced proteinase K (PK)-resistant, insoluble, and aggregated assemblies that were infectious for naïve cells expressing either the mutant protein or other PrPs with slightly different deletions in the same area. The electrophoretic pattern of the PK-resistant core of the spontaneous prion (Δ^Spont) contained mainly C-terminal polypeptides akin to C1, the cell-surface anchored C-terminal moiety of PrP generated by natural cellular processing. RK13 cells expressing solely the Δ190-196 C1 PrP construct, in the absence of the full-length protein, were susceptible to Δ^Spont prions. Δ^Spont infection induced the conversion of the mutated C1 into a PK-resistant and infectious form perpetuating the biochemical characteristics of Δ^Spont prion. In conclusion, this work provides a unique cell-derived system generating spontaneous prions and provides evidence that the 113 C-terminal residues of PrP are sufficient for a self-propagating prion entity.

Mutations in Prion Protein Gene: Pathogenic Mechanisms in C-Terminal vs. N-Terminal Domain, a Review

Inherited mutations in the Prion protein (PrP), encoded by the PRNP gene, have been associated with autosomal dominant neurodegenerative disorders, such as Creutzfeldt-Jacob disease (CJD), Gerstmann-Sträussler-Scheinker syndrome (GSS), and Fatal Familial Insomnia (FFI). Notably, PRNP mutations have also been described in clinical pictures resembling other neurodegenerative diseases, such as frontotemporal dementia. Regarding the pathogenesis, it has been observed that these point mutations are located in the C-terminal region of the PRNP gene and, currently, the potential significance of the N-terminal domain has largely been underestimated. The purpose of this report is to review and provide current insights into the pathogenic mechanisms of PRNP mutations, emphasizing the differences between the C- and N-terminal regions and focusing, in particular, on the lesser-known flexible N-terminal, for which recent biophysical evidence has revealed a physical interaction with the globular C-terminal domain of the cellular prion protein (PrPC).