Cellular Prion Protein Mediates α-Synuclein Uptake, Localization, and Toxicity In Vitro and In Vivo.

BACKGROUND: The cellular prion protein (PrPC ) is a membrane-bound, multifunctional protein mainly expressed in neuronal tissues. Recent studies indicate that the native trafficking of PrPC can be misused to internalize misfolded amyloid beta and α-synuclein (aSyn) oligomers. OBJECTIVES: We define PrPC 's role in internalizing misfolded aSyn in α-synucleinopathies and identify further involved proteins. METHODS: We performed comprehensive behavioral studies on four transgenic mouse models (ThySyn and ThySynPrP00, TgM83 and TgMPrP00) at different ages. We developed PrPC -(over)-expressing cell models (cell line and primary cortical neurons), used confocal laser microscopy to perform colocalization studies, applied mass spectrometry to identify interactomes, and determined disassociation constants using surface plasmon resonance (SPR) spectroscopy. RESULTS: Behavioral deficits (memory, anxiety, locomotion, etc.), reduced lifespans, and higher oligomeric aSyn levels were observed in PrPC -expressing mice (ThySyn and TgM83), but not in homologous Prnp ablated mice (ThySynPrP00 and TgMPrP00). PrPC colocalized with and facilitated aSyn (oligomeric and monomeric) internalization in our cell-based models. Glimepiride treatment of PrPC -overexpressing cells reduced aSyn internalization in a dose-dependent manner. SPR analysis showed that the binding affinity of PrPC to monomeric aSyn was lower than to oligomeric aSyn. Mass spectrometry-based proteomic studies identified clathrin in the immunoprecipitates of PrPC and aSyn. SPR was used to show that clathrin binds to recombinant PrP, but not aSyn. Experimental disruption of clathrin-coated vesicles significantly decreased aSyn internalization. CONCLUSION: PrPC 's native trafficking can be misused to internalize misfolded aSyn through a clathrin-based mechanism, which may facilitate the spreading of pathological aSyn. Disruption of aSyn-PrPC binding is, therefore, an appealing therapeutic target in α-synucleinopathies. © 2021 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Ligands binding to the prion protein induce its proteolytic release with therapeutic potential in neurodegenerative proteinopathies.

The prion protein (PrPC) is a central player in neurodegenerative diseases, such as prion diseases or Alzheimer's disease. In contrast to disease-promoting cell surface PrPC, extracellular fragments act neuroprotective by blocking neurotoxic disease-associated protein conformers. Fittingly, PrPC release by the metalloprotease ADAM10 represents a protective mechanism. We used biochemical, cell biological, morphological, and structural methods to investigate mechanisms stimulating this proteolytic shedding. Shed PrP negatively correlates with prion conversion and is markedly redistributed in murine brain in the presence of prion deposits or amyloid plaques, indicating a sequestrating activity. PrP-directed ligands cause structural changes in PrPC and increased shedding in cells and organotypic brain slice cultures. As an exception, some PrP-directed antibodies targeting repetitive epitopes do not cause shedding but surface clustering, endocytosis, and degradation of PrPC. Both mechanisms may contribute to beneficial actions described for PrP-directed ligands and pave the way for new therapeutic strategies against currently incurable neurodegenerative diseases.

Cerebrospinal Fluid Prion Disease Biomarkers in Pre-clinical and Clinical Naturally Occurring Scrapie.

The analysis of the cerebrospinal fluid (CSF) biomarkers in patients with suspected prion diseases became a useful tool in diagnostic routine. Prion diseases can only be identified at clinical stages when the disease already spread throughout the brain and massive neuronal damage occurs. Consequently, the accuracy of CSF tests detecting non-symptomatic patients is unknown. Here, we aimed to investigate the usefulness of CSF-based diagnostic tests in pre-clinical and clinical naturally occurring scrapie. While decreased total prion protein (PrP) levels and positive PrP seeding activity were already detectable at pre-symptomatic stages, the surrogate markers of neuronal damage total tau (tau) and 14-3-3 proteins were exclusively increased at clinical stages. The present findings confirm that alterations in PrP levels and conformation are primary events in the pathology of prion diseases preceding neuronal damage. Our work also supports the potential use of these tests in the screening of pre-symptomatic scrapie and human prion disease cases.

YKL-40 in the brain and cerebrospinal fluid of neurodegenerative dementias.

BACKGROUND: YKL-40 (also known as Chitinase 3-like 1) is a glycoprotein produced by inflammatory, cancer and stem cells. Its physiological role is not completely understood but YKL-40 is elevated in the brain and cerebrospinal fluid (CSF) in several neurological and neurodegenerative diseases associated with inflammatory processes. Yet the precise characterization of YKL-40 in dementia cases is missing. METHODS: In the present study, we comparatively analysed YKL-40 levels in the brain and CSF samples from neurodegenerative dementias of different aetiologies characterized by the presence of cortical pathology and disease-specific neuroinflammatory signatures. RESULTS: YKL-40 was normally expressed in fibrillar astrocytes in the white matter. Additionally YKL-40 was highly and widely expressed in reactive protoplasmic cortical and perivascular astrocytes, and fibrillar astrocytes in sporadic Creutzfeldt-Jakob disease (sCJD). Elevated YKL-40 levels were also detected in Alzheimer's disease (AD) but not in dementia with Lewy bodies (DLB). In AD, YKL-40-positive astrocytes were commonly found in clusters, often around ß-amyloid plaques, and surrounding vessels with ß-amyloid angiopathy; they were also distributed randomly in the cerebral cortex and white matter. YKL-40 overexpression appeared as a pre-clinical event as demonstrated in experimental models of prion diseases and AD pathology. CSF YKL-40 levels were measured in a cohort of 288 individuals, including neurological controls (NC) and patients diagnosed with different types of dementia. Compared to NC, increased YKL-40 levels were detected in sCJD (p < 0.001, AUC = 0.92) and AD (p < 0.001, AUC = 0.77) but not in vascular dementia (VaD) (p > 0.05, AUC = 0.71) or in DLB/Parkinson's disease dementia (PDD) (p > 0.05, AUC = 0.70). Further, two independent patient cohorts were used to validate the increased CSF YKL-40 levels in sCJD. Additionally, increased YKL-40 levels were found in genetic prion diseases associated with the PRNP-D178N (Fatal Familial Insomnia) and PRNP-E200K mutations. CONCLUSIONS: Our results unequivocally demonstrate that in neurodegenerative dementias, YKL-40 is a disease-specific marker of neuroinflammation showing its highest levels in prion diseases. Therefore, YKL-40 quantification might have a potential for application in the evaluation of therapeutic intervention in dementias with a neuroinflammatory component.

Regulation of human cerebrospinal fluid malate dehydrogenase 1 in sporadic Creutzfeldt-Jakob disease patients.

The identification of reliable diagnostic biomarkers in differential diagnosis of neurodegenerative diseases is an ongoing topic. A previous two-dimensional proteomic study on cerebrospinal fluid (CSF) revealed an elevated level of an enzyme, mitochondrial malate dehydrogenase 1 (MDH1), in sporadic Creutzfeldt-Jakob disease (sCJD) patients. Here, we could demonstrate the expression of MDH1 in neurons as well as in the neuropil. Its levels are lower in sCJD brains than in control brains. An examination of CSF-MDH1 in sCJD patients by ELISA revealed a significant elevation of CSF-MDH1 levels in sCJD patients (independently from the PRNP codon 129 MV genotype or the prion protein scrapie (PrPSc) type) in comparison to controls. In combination with total tau (tau), CSF-MDH1 detection exhibited a high diagnostic accuracy for sCJD diagnosis with a sensitivity of 97.5% and a specificity of 95.6%. A correlation study of MDH1 level in CSF with other neurodegenerative marker proteins revealed a significant positive correlation between MDH1 concentration with tau, 14-3-3 and neuron specific enolase level. In conclusion, our study indicated the potential of MDH1 in combination with tau as an additional biomarker in sCJD improving diagnostic accuracy of tau markedly.

Megacólon psicogênico em gêmeos: relato de caso / Psychogenic megacolon in twins: case report

Megacólon psicogênico (MP) é uma doença difícil de ser diagnosticada. O artigo propõe a descrever um caso de MP em crianças gêmeas com idade de 6 anos. Sua relevância científica está na escassez de relatos na literatura sobre gêmeos que possuem esta patologia ao mesmo tempo.

Psychogenic Megacolon (MP) is a disease hard to diagnose. The article aims to describe a MP case in twin children at the age of six years. The scientific relevance of this submission lies in the scarcity of reports on twins with this same pathology at the same time.

Estudo de caracterização do fruto cambuci [campomanesia phaea (o. berg.) landrum] e suaaplicação no processamento de geleia / Characterization study of cambuci fruit [campomanesia phaea (o. Berg.) Landrum] and its application in jelly processing

O objetivo deste trabalho foi estudar possível diferença de variedades de cambuci, informada por produtores, mediante a caracterização do fruto e a elaboração de geleia. Os frutos foramseparados pelas quatro possíveis variedades, denominadas A, B,C e D, e analisados quanto ao peso médio, cinzas, umidade, pH,sólidos solúveis, acidez titulável, ratio, ácido ascórbico e atividade de água. Para a elaboração da geleia foi escolhida a variedade A com duas formulações, 50%50% e 40%60% fruto e açúcar,respectivamente. Para as possíveis variedades de cambuci, somente a atividade de água não apresentou diferença signifi cativa. A acidez e o ratio da variedade B chamam a atenção, pois diferiram das demais indicando fruto mais propício ao consumo in natura. Emtodas as outras análises existiu diferença estatística de pelo menos uma variedade, mas esses dados devem ser vistos com cautela por sofrerem infl uência de condições edafoclimáticas. A amostrade geleia com 60% de açúcar apresentou resultados menores parapH, acidez, luminosidade e ohue, o que contribuiu para os melhoresresultados no teste de preferência em todos os atributos avaliados(aparência, cor, sabor e textura), exceto quanto ao aroma em que ambas as amostras (50% e 60%) não diferiram.