Human Neurodegenerative Diseases Research Articles

Sigma Receptor Ligands Are Potent Antiprion Compounds that Act Independently of Sigma Receptor Binding.

Prion diseases are invariably fatal neurodegenerative diseases of humans and other animals for which there are no effective treatment options. Previous work from our laboratory identified phenethylpiperidines as a novel class of anti-prion compounds. While working to identify the molecular target(s) of these molecules, we unexpectedly discovered ten novel antiprion compounds based on their known ability to bind to the sigma receptors, σ1R and σ2R, which are currently being tested as therapeutic or diagnostic targets for cancer and neuropsychiatric disorders. Surprisingly, however, knockout of the respective genes encoding σ1R and σ2R (Sigmar1 and Tmem97) in prion-infected N2a cells did not alter the antiprion activity of these compounds, demonstrating that these receptors are not the direct targets responsible for the antiprion effects of their ligands. Further investigation of the most potent molecules established that they are efficacious against multiple prion strains and protect against downstream prion-mediated synaptotoxicity. While the precise details of the mechanism of action of these molecules remain to be determined, the present work forms the basis for further investigation of these compounds in preclinical studies. Given the therapeutic utility of several of the tested compounds, including rimcazole and haloperidol for neuropsychiatric conditions, (+)-pentazocine for neuropathic pain, and the ongoing clinical trials of SA 4503 and ANAVEX2-73 for ischemic stroke and Alzheimer's disease, respectively, this work has immediate implications for the treatment of human prion disease.

NADPH and NAC synergistically inhibits chronic ocular hypertension-induced neurodegeneration and neuroinflammation through regulating p38/MAPK pathway and peroxidation

Glaucoma, the leading cause of irreversible blindness worldwide, is characterized by neurodegeneration and neuroinflammation with retinal NAD/NADP and GSH decline. Nicotinamide adenine dinucleotide (NAD)/NAD phosphate (NADP) and glutathione (GSH) are two redox reducers in neuronal and glial metabolism. However, therapeutic strategies targeting NAD/NADP or GSH do not exert ideal effects, and the underlying mechanisms are still poorly understood. We assessed morphological changes in retinal ganglion cells (RGCs), the affected neurons in glaucoma, and Müller cells, the major glial cells in the retina, as well as the levels of phosphorylated p38 (p-p38) and Caspase-3 in glaucoma patients. We constructed a modified chronic ocular hypertensive rat model and an oxygen-glucose deprivation (OGD) cell model. After applying NADPH and N-acetylcysteine (NAC), a precursor to cysteine, the rate-limiting substrate in GSH biosynthesis, to cells, apoptosis, axonal damage and peroxidation were reduced in the RGCs of the NAC group and p-p38 levels were decreased in the RGCs of the NADPH group, while in stimulated Müller cells cultured individually or cocultured with RGCs, gliosis and p38/MAPK, rather than JNK/MAPK, activation were inhibited. The results were more synergistic in the rat model, where either NADPH or NAC showed crossover effects on inhibiting peroxidation and p38/MAPK pathway activation. Moreover, the combination of NADPH and NAC ameliorated RGC electrophysiological function and prevented Müller cell gliosis to the greatest extent. These data illustrated conjoined mechanisms in glaucomatous RGC injury and Müller cell gliosis and suggested that NADPH and NAC collaborate as a neuroprotective and anti-inflammatory combination treatment for glaucoma and other underlying human neurodegenerative diseases.

TNF-α/TNFR1 activated astrocytes exacerbate depression-like behavior in CUMS mice

Neuroinflammation is considered to be a significant mechanism contributing to depression. Several studies have reported that A1 astrocytes were highly prevalent in human neuroinflammatory and neurodegenerative diseases. However, the precise mechanism by which A1 astrocytes contribute to depression remains unclear. Clinical studies have suggested a correlation between TNF-α, an activator of A1 astrocytes, and the severity of depression. Based on these findings, we hypothesized that TNF-α might worsen depression by activating A1 astrocytes. Our previous studies indicated that Rhodomyrtone (Rho) has the potential to improve depression-like behavior in mice. However, the exact mechanism for this effect has not been fully elucidated. Importantly, it was reported that Rho alleviated skin inflammation in a mouse model of psoriasis by inhibiting the expression of TNF-α. Based on this finding, we hypothesized that rhodomyrtone may exert antidepressant effects by modulating the TNF-α pathway. However, further research is required to investigate and validate these hypotheses, shedding light on the relationships between neuroinflammation, A1 astrocytes, TNF-α, and depression. By obtaining a deeper understanding of the underlying mechanisms, these findings could lead to the development of novel antidepressant strategies that target the TNF-α pathway in the context of neuroinflammation. In vivo, based on the established chronic unpredictable mild stress (CUMS) mouse depression model, we characterized the mechanism of TNF-α and Rho during depression by using several behavioral assays, adeno-associated virus(AAV) transfection, western blotting, immunofluorescence, and other experimental methods. In vitro, we characterized the effect of Rho on inflammation in TNF-α-treated primary astrocytes. TNFR1 expression was significantly increased in the hippocampus of depression-like mice, with increased astrocytes activation and neuronal apoptosis. These processes were further enhanced with increasing levels of TNF-α in the cerebrospinal fluid of mice. However, this process was attenuated by knockdown of TNFR1 and infliximab (Inf; a TNF-α antagonist). Injection of rhodomyrtone decreased the expressions of TNFR1 and TNF-α, resulting in significant improvements in mouse depression-like behaviors and reduction of astrocyte activation. TNF-α could be involved in the pathophysiological process of depression, through mediating astrocytes activation by binding to TNFR1. By blocking this pathway, Rho may be a novel antidepressant.

Evaluating the human neurotoxicity and toxicological interactions impact of co-occurring regulated and emerging mycotoxins

Mycotoxins can inflict harmful effects on diverse organs, and mounting evidence indicates their potential involvement in human neurodegenerative diseases. Given the common occurrence of these toxins in food, there is an increasing demand for a comprehensive assessment of their combined toxicity to enhance our understanding of their potential hazards. This research investigates mycotoxin exposure from widely consumed cereal-based products, including enniatin B (ENNB), sterigmatocystin (STG), aflatoxin B1 (AFB1), cyclopiazonic acid (CPZ), citrinin (CIT), and ochratoxin A (OTA). Employing the median-effect equation based on Chou and Talalay's mass-action law, we assessed their cytotoxicity in human SH-SY5Y neuronal cells. Notably, ENNB displayed the highest neurotoxicity (IC50 = 3.72 µM), followed by OTA (9.10 µM) and STG (9.99 µM). The combination of OTA + STG exhibited the highest toxicity (IC50 = 3.77 µM), while CPZ + CIT showed the least detrimental effect. Approximately 70 % of tested binary combinations displayed synergistic or additive effects, except for ENNB + STG, ENNB + AFB1, and CPZ + CIT, which showed antagonistic interactions. Intriguingly, the senary combination displayed moderate antagonism at the lowest exposure and moderate synergism at higher doses. OTA exhibited predominantly synergistic interactions, comprising approximately 90 %, a noteworthy finding considering its prevalence in food. Conversely, ENNB interactions tended to be antagonistic. The most remarkable synergy occurred in the STG and CIT combination, enabling a 50-fold reduction in CIT dosage for an equivalent toxic effect. These findings highlight the biological relevance of robust synergistic interactions, emphasizing the need to assess human exposure hazards accurately, particularly considering frequent mycotoxin co-occurrence in environmental and food settings.

Cloud-Connected Bracelet for Continuous Monitoring of Parkinson’s Disease Patients: Integrating Advanced Wearable Technologies and Machine Learning

Parkinson’s disease (PD) is one of the most unremitting and dynamic neurodegenerative human diseases. Various wearable IoT devices have emerged for detecting, diagnosing, and quantifying PD, predominantly utilizing inertial sensors and computational algorithms. However, their proliferation poses novel challenges concerning security, privacy, connectivity, and power optimization. Clinically, continuous monitoring of patients’ motor function is imperative for optimizing Levodopa (L-dopa) dosage while mitigating adverse effects and motor activity decline. Tracking motor function alterations between visits is challenging, risking erroneous clinical decisions. Thus, there is a pressing need to furnish medical professionals with an ecosystem facilitating comprehensive Parkinson’s stage evaluation and disease progression monitoring, particularly regarding tremor and bradykinesia. This study endeavors to establish a holistic ecosystem centered around an energy-efficient Wi-Fi-enabled wearable bracelet dubbed A-WEAR. A-WEAR functions as a data collection conduit for Parkinson’s-related motion data, securely transmitting them to the Cloud for storage, processing, and severity estimation via bespoke learning algorithms. The experimental results demonstrate the resilience and effectiveness of the suggested technique, with 86.4% accuracy for bradykinesia and 90.9% accuracy for tremor estimation, along with good sensitivity and specificity for each scoring class. The recommended approach will support the timely determination of the severity of PD and ongoing patient activity monitoring. The system helps medical practitioners in decision making when initially assessing patients with PD and reviewing their progress and the effects of any treatment.

Perspective: The Impact of Fasting and Caloric Restriction on Neurodegenerative Diseases in Humans

Neurodegenerative diseases (NDs) are characterized by the progressive functional and structural denaturation of neurons in the central and peripheral nervous systems. Despite the wide range of genetic predispositions, the increased emergence of these disorders has been associated with a variety of modifiable risk factors, including lifestyle factors. Diet has been shown to influence cognitive alterations in the elderly population with age-related brain pathologies, and specific dietary interventions might, therefore, confer preservatory protection to neural structures. Although Mediterranean and ketogenic diets have been studied, no clear guidelines have been implemented for the prevention or treatment of ND in clinical practice. Murine models have shown that intermittent fasting and caloric restriction (CR) can counteract disease processes in various age-related disorders, including NDs. The objective of this perspective is to provide a comprehensive, comparative overview of the available primary intervention studies on fasting and CR in humans with ND and to elucidate possible links between the mechanisms underlying the effects of fasting, CR, and the neuropathology of ND. We also included all currently available studies in older adults (with and without mild cognitive impairment) in which the primary endpoint was cognitive function to provide further insights into the feasibility and outcomes of such interventions. Overall, we conclude that nutritional intervention trials focusing on fasting and CR in humans with ND have been neglected, and more high-quality studies, including longitudinal clinical intervention trials, are urgently needed to elucidate the underlying immune–metabolic mechanisms in diet and ND.

Identification and Analysis of Axolotl Homologs for Proteins Implicated in Human Neurodegenerative Proteinopathies.

Neurodegenerative proteinopathies such as Alzheimer's Disease are characterized by abnormal protein aggregation and neurodegeneration. Neuroresilience or regenerative strategies to prevent neurodegeneration, preserve function, or restore lost neurons may have the potential to combat human proteinopathies; however, the adult human brain possesses a limited capacity to replace lost neurons. In contrast, axolotls (Ambystoma mexicanum) show robust brain regeneration. To determine whether axolotls may help identify potential neuroresilience or regenerative strategies in humans, we first interrogated whether axolotls express putative proteins homologous to human proteins associated with neurodegenerative diseases. We compared the homology between human and axolotl proteins implicated in human proteinopathies and found that axolotls encode proteins highly similar to human microtubule-binding protein tau (tau), amyloid precursor protein (APP), and β-secretase 1 (BACE1), which are critically involved in human proteinopathies like Alzheimer's Disease. We then tested monoclonal Tau and BACE1 antibodies previously used in human and rodent neurodegenerative disease studies using immunohistochemistry and western blotting to validate the homology for these proteins. These studies suggest that axolotls may prove useful in studying the role of these proteins in disease within the context of neuroresilience and repair.

Interplay between autophagy and CncC regulates dendrite pruning in Drosophila

Autophagy is essential for the turnover of damaged organelles and long-lived proteins. It is responsible for many biological processes such as maintaining brain functions and aging. Impaired autophagy is often linked to neurodevelopmental and neurodegenerative diseases in humans. However, the role of autophagy in neuronal pruning during development remains poorly understood. Here, we report that autophagy regulates dendrite-specific pruning of ddaC sensory neurons in parallel to local caspase activation. Impaired autophagy causes the formation of ubiquitinated protein aggregates in ddaC neurons, dependent on the autophagic receptor Ref(2)P. Furthermore, the metabolic regulator AMP-activated protein kinase and the insulin-target of rapamycin pathway act upstream to regulate autophagy during dendrite pruning. Importantly, autophagy is required to activate the transcription factor CncC (Cap "n" collar isoform C), thereby promoting dendrite pruning. Conversely, CncC also indirectly affects autophagic activity via proteasomal degradation, as impaired CncC results in the inhibition of autophagy through sequestration of Atg8a into ubiquitinated protein aggregates. Thus, this study demonstrates the important role of autophagy in activating CncC prior to dendrite pruning, and further reveals an interplay between autophagy and CncC in neuronal pruning.

Ferritinophagy: A novel insight into the double-edged sword in ferritinophagy-ferroptosis axis and human diseases.

Nuclear receptor coactive 4 (NCOA4), which functions as a selective cargo receptor, is a critical regulator of the particularly autophagic degradation of ferritin, a process known as ferritinophagy. Mechanistically, NCOA4-mediated ferritinophagy performs an increasingly vital role in the maintenance of intracellular iron homeostasis by promoting ferritin transport and iron release as needed. Ferritinophagy is not only involved in iron-dependent responses but also in the pathogenesis and progression of various human diseases, including metabolism-related, neurodegenerative, cardiovascular and infectious diseases. Therefore, ferritinophagy is of great importance in maintaining cell viability and function and represents a potential therapeutic target. Recent studies indicated that ferritinophagy regulates the signalling pathway associated with ferroptosis, a newly discovered type of cell death characterised by iron-dependent lipid peroxidation. Although accumulating evidence clearly demonstrates the importance of the interplay between dysfunction in iron metabolism and ferroptosis, a deeper understanding of the double-edged sword effect of ferritinophagy in ferroptosis has remained elusive. Details of the mechanisms underlying the ferritinophagy-ferroptosis axis in regulating relevant human diseases remain to be elucidated. In this review, we discuss the latest research findings regarding the mechanisms that regulate the biological function of NCOA4-mediated ferritinophagy and its contribution to the pathophysiology of ferroptosis. The important role of the ferritinophagy-ferroptosis axis in human diseases will be discussed in detail, highlighting the great potential of targeting ferritinophagy in the treatment of diseases.

SRF-deficient astrocytes provide neuroprotection in mouse models of excitotoxicity and neurodegeneration.

Reactive astrogliosis is a common pathological hallmark of CNS injury, infection, and neurodegeneration, where reactive astrocytes can be protective or detrimental to normal brain functions. Currently, the mechanisms regulating neuroprotective astrocytes and the extent of neuroprotection are poorly understood. Here, we report that conditional deletion of serum response factor (SRF) in adult astrocytes causes reactive-like hypertrophic astrocytes throughout the mouse brain. These SrfGFAP-ERCKO astrocytes do not affect neuron survival, synapse numbers, synaptic plasticity or learning and memory. However, the brains of Srf knockout mice exhibited neuroprotection against kainic-acid induced excitotoxic cell death. Relevant to human neurodegenerative diseases, SrfGFAP-ERCKO astrocytes abrogate nigral dopaminergic neuron death and reduce β-amyloid plaques in mouse models of Parkinson's and Alzheimer's disease, respectively. Taken together, these findings establish SRF as a key molecular switch for the generation of reactive astrocytes with neuroprotective functions that attenuate neuronal injury in the setting of neurodegenerative diseases.

High-Resolution NMR Structures of Intrastrand Hairpins Formed by CTG Trinucleotide Repeats.

The CAG and CTG trinucleotide repeat expansions cause more than 10 human neurodegenerative diseases. Intrastrand hairpins formed by trinucleotide repeats contribute to repeat expansions, establishing them as potential drug targets. High-resolution structural determination of CAG and CTG hairpins poses as a long-standing goal to aid drug development, yet it has not been realized due to the intrinsic conformational flexibility of repetitive sequences. We herein investigate the solution structures of CTG hairpins using nuclear magnetic resonance (NMR) spectroscopy and found that four CTG repeats with a clamping G-C base pair was able to form a stable hairpin structure. We determine the first solution NMR structure of dG(CTG)4C hairpin and decipher a type I folding geometry of the TGCT tetraloop, wherein the two thymine residues form a T·T loop-closing base pair and the first three loop residues continuously stack. We further reveal that the CTG hairpin can be bound and stabilized by a small-molecule ligand, and the binding interferes with replication of a DNA template containing CTG repeats. Our determined high-resolution structures lay an important foundation for studying molecular interactions between native CTG hairpins and ligands, and benefit drug development for trinucleotide repeat expansion diseases.

Comprehensive perspective towards the management of proteinopathies by elucidating protein misfolding and aggregation.

Protein misfolding and aggregation is the phenomenon of the generic propensity of proteins, considered as a dark side of the protein world, and its exact mechanism is still not deciphered. Understanding the complexity of protein aggregation is currently the primary apprehension and challenge in biology and medicine due to their association with various debilitating human proteinopathies and neurodegenerative diseases. The mechanism of protein aggregation, associated diseases, and the development of efficient therapeutic strategies against these diseases are very challenging. These diseases are caused by different proteins, each protein with different mechanisms and consisting of various microscopic phases or events. These microscopic steps are functioning on different timescales during aggregation. Here, we highlighted the different features and current trends in protein aggregation. The study thoroughly recapitulates the various factors influencing, possible causes, types of aggregates and aggregation, their different proposed mechanisms, and the methods used to study the aggregation. Additionally, the formation and elimination of misfolded or aggregated proteins in the cell, the role of the ruggedness of the protein folding landscape in protein aggregation, proteinopathies, and the challenges for their prevention are comprehensively elucidated. A holistic understanding of different aspects of aggregation, molecular steps governing the various features of protein quality control, and crucial queries about the modulation of these processes and their interactions with other systems in cellular protein quality control can be considered conducive to comprehending the mechanism, designing effective approaches towards prevention of protein aggregation, rationalizing the etiology and development of novel strategies against therapy and management of the proteinopathies.

TDP-43 impairs sleep in Drosophila through Ataxin-2-dependent metabolic disturbance.

Neurodegenerative diseases such as amyotrophic lateral sclerosis and frontotemporal dementia are associated with substantial sleep disruption, which may accelerate cognitive decline and brain degeneration. Here, we define a role for trans-activation response element (TAR) DNA binding protein 43 (TDP-43), a protein associated with human neurodegenerative disease, in regulating sleep using Drosophila. Expression of TDP-43 severely disrupts sleep, and the sleep deficit is rescued by Atx2 knockdown. Brain RNA sequencing revealed that Atx2 RNA interference regulates transcripts enriched for small-molecule metabolic signaling in TDP-43 brains. Focusing on these Atx2-regulated genes, we identified suppressors of the TDP-43 sleep phenotype enriched for metabolism pathways. Knockdown of Atx2 or treatment with rapamycin attenuated the sleep phenotype and mitigated the disruption of small-molecule glycogen metabolism caused by TDP-43. Our findings provide a connection between toxicity of TDP-43 and sleep disturbances and highlight key aspects of metabolism that interplay with TDP-43 toxicity upon Atx2 rescue.

Measurement of 8-hydroxy-2'-deoxyguanosine in serum and cerebrospinal fluid of horses with neuroaxonal degeneration and other causes of proprioceptive ataxia.

Eight-hydroxy-2'-deoxyguanosine (8-OHdG), a biomarker of oxidative damage evaluated in human neurodegenerative disease, has potential to correlate with postmortem diagnosis of neuroaxonal dystrophy/degenerative myeloencephalopathy (NAD/DM) in horses. We hypothesized that 8-OHdG will be higher in CSF and serum from NAD/DM horses compared with horses with other neurologic diseases (CVSM, EPM) and a control group of neurologically normal horses. We also hypothesized that 8-OHdG will be higher in CSF compared with serum from NAD/DM horses. Fifty client-owned horses with postmortem diagnoses: 20 NAD/DM, 10 CVSM, 10 EPM, and 10 control horses. Serum and CSF samples were obtained between November 2010 and March 2022. Case-control study using biobanked samples was performed and commercial competitive ELISA kit (Highly Sensitive 8-OHdG Check ELISA) utilized. Concentration of 8-OHdG was quantitated in both CSF and serum and compared between groups. No correlation was established between the measures of 8-OHdG in serum and CSF and group. CSF median [8-OHdG] for NAD/DM was 169.9 pg/mL (IQR25-75 : 67.18-210.6), CVSM 157.1 pg/mL (IQR25-75 : 132.1-229.1), EPM 131.4 pg/mL (IQR25-75 : 102.1-193.2), and control 149.8 pg/mL (IQR25-75 : 113.3-196.4). Serum median [8-OHdG] for NAD/DM was 130 pg/mL (IQR25-75 : 51.73-157.2), CVSM 125.8 pg/mL (IQR25-75 : 62.8-170.8), EPM 120.6 pg/mL (IQR25-75 : 87.23-229.7), and control 157.6 pg/mL (IQR25-75 : 97.15-245.6). Poisson regression analysis showed no difference established once confounding variables were considered. Eight-OHdG did not aid in antemortem diagnosis of NAD/DM in this cohort of horses. At the time of diagnosis horses with NAD/DM do not have ongoing oxidative stress.

SV2A PET imaging in human neurodegenerative diseases.

This manuscript presents a thorough review of synaptic vesicle glycoprotein 2A (SV2A) as a biomarker for synaptic integrity using Positron Emission Tomography (PET) in neurodegenerative diseases. Synaptic pathology, characterized by synaptic loss, has been linked to various brain diseases. Therefore, there is a need for a minimally invasive approach to measuring synaptic density in living human patients. Several radiotracers targeting synaptic vesicle protein 2A (SV2A) have been created and effectively adapted for use in human subjects through PET scans. SV2A is an integral glycoprotein found in the membranes of synaptic vesicles in all synaptic terminals and is widely distributed throughout the brain. The review delves into the development of SV2A-specific PET radiotracers, highlighting their advancements and limitations in neurodegenerative diseases. Among these tracers, 11C-UCB-J is the most used so far. We summarize and discuss an increasing body of research that compares measurements of synaptic density using SV2A PET with other established indicators of neurodegenerative diseases, including cognitive performance and radiological findings, thus providing a comprehensive analysis of SV2A's effectiveness and reliability as a diagnostic tool in contrast to traditional markers. Although the literature overall suggests the promise of SV2A as a diagnostic and therapeutic monitoring tool, uncertainties persist regarding the superiority of SV2A as a biomarker compared to other available markers. The review also underscores the paucity of studies characterizing SV2A distribution and loss in human brain tissue from patients with neurodegenerative diseases, emphasizing the need to generate quantitative neuropathological maps of SV2A density in cases with neurodegenerative diseases to fully harness the potential of SV2A PET imaging in clinical settings. We conclude by outlining future research directions, stressing the importance of integrating SV2A PET imaging with other biomarkers and clinical assessments and the need for longitudinal studies to track SV2A changes throughout neurodegenerative disease progression, which could lead to breakthroughs in early diagnosis and the evaluation of new treatments.

Aggregation and Oligomerization Characterization of ß-Lactoglobulin Protein Using a Solid-State Nanopore Sensor.

Protein aggregation is linked to many chronic and devastating neurodegenerative human diseases and is strongly associated with aging. This work demonstrates that protein aggregation and oligomerization can be evaluated by a solid-state nanopore method at the single molecule level. A silicon nitride nanopore sensor was used to characterize both the amyloidogenic and native-state oligomerization of a model protein ß-lactoglobulin variant A (βLGa). The findings from the nanopore measurements are validated against atomic force microscopy (AFM) and dynamic light scattering (DLS) data, comparing βLGa aggregation from the same samples at various stages. By calibrating with linear and circular dsDNA, this study estimates the amyloid fibrils' length and diameter, the quantity of the βLGa aggregates, and their distribution. The nanopore results align with the DLS and AFM data and offer additional insight at the level of individual protein molecular assemblies. As a further demonstration of the nanopore technique, βLGa self-association and aggregation at pH 4.6 as a function of temperature were measured at high (2 M KCl) and low (0.1 M KCl) ionic strength. This research highlights the advantages and limitations of using solid-state nanopore methods for analyzing protein aggregation.

Human WIPI β-propeller function in autophagy and neurodegeneration.

The four human WIPI β-propellers, WIPI1 through WIPI4, belong to the ancient PROPPIN family and fulfill scaffold functions in the control of autophagy. In this context, WIPI β-propellers function as PI3P effectors during autophagosome formation and loss of WIPI function negatively impacts autophagy and contributes to neurodegeneration. Of particular interest are mutations in WDR45, the human gene that encodes WIPI4. Sporadic WDR45 mutations are the cause of a rare human neurodegenerative disease called BPAN, hallmarked by high brain iron accumulation. Here, we discuss the current understanding of the functions of human WIPI β-propellers and address unanswered questions with a particular focus on the role of WIPI4 in autophagy and BPAN.

Protease-Sensitive and -Resistant Forms of Human and Murine Alpha-Synucleins in Distinct Brain Regions of Transgenic Mice (M83) Expressing the Human Mutated A53T Protein.

Human neurodegenerative diseases associated with the misfolding of the alpha-synuclein (aS) protein (synucleinopathies) are similar to prion diseases to the extent that lesions are spread by similar molecular mechanisms. In a transgenic mouse model (M83) overexpressing a mutated (A53T) form of human aS, we had previously found that Protein Misfolding Cyclic Amplification (PMCA) triggered the aggregation of aS, which is associated with a high resistance to the proteinase K (PK) digestion of both human and murine aS, a major hallmark of the disease-associated prion protein. In addition, PMCA was also able to trigger the aggregation of murine aS in C57Bl/6 mouse brains after seeding with sick M83 mouse brains. Here, we show that intracerebral inoculations of M83 mice with C57Bl/6-PMCA samples strikingly shortens the incubation period before the typical paralysis that develops in this transgenic model, demonstrating the pathogenicity of PMCA-aggregated murine aS. In the hind brain regions of these sick M83 mice containing lesions with an accumulation of aS phosphorylated at serine 129, aS also showed a high PK resistance in the N-terminal part of the protein. In contrast to M83 mice, old APPxM83 mice co-expressing human mutated amyloid precursor and presenilin 1 proteins were seen to have an aggregation of aS, especially in the cerebral cortex, hippocampus and striatum, which also contained the highest load of aS phosphorylated at serine 129. This was proven by three techniques: a Western blot analysis of PK-resistant aS; an ELISA detection of aS aggregates; or the identification of aggregates of aS using immunohistochemical analyses of cytoplasmic/neuritic aS deposits. The results obtained with the D37A6 antibody suggest a higher involvement of murine aS in APPxM83 mice than in M83 mice. Our study used novel tools for the molecular study of synucleinopathies, which highlight similarities with the molecular mechanisms involved in prion diseases.

Saccharomyces cerevisiae as a Model for Studying Human Neurodegenerative Disorders: Viral Capsid Protein Expression.

In this article, we briefly describe human neurodegenerative diseases (NDs) and the experimental models used to study them. The main focus is the yeast Saccharomyces cerevisiae as an experimental model used to study neurodegenerative processes. We review recent experimental data on the aggregation of human neurodegenerative disease-related proteins in yeast cells. In addition, we describe the results of studies that were designed to investigate the molecular mechanisms that underlie the aggregation of reporter proteins. The advantages and disadvantages of the experimental approaches that are currently used to study the formation of protein aggregates are described. Special attention is given to the similarity between aggregates that form as a result of protein misfolding and viral factories-special structural formations in which viral particles are formed inside virus-infected cells. A separate part of the review is devoted to our previously published study on the formation of aggregates upon expression of the insect densovirus capsid protein in yeast cells. Based on the reviewed results of studies on NDs and related protein aggregation, as well as viral protein aggregation, a new experimental model system for the study of human NDs is proposed. The core of the proposed system is a comparative transcriptomic analysis of changes in signaling pathways during the expression of viral capsid proteins in yeast cells.

Applications of hybrid structure light three‐dimensional scanning in neurodegenerative disease autopsy brain banking

AbstractBackgroundPostmortem magnetic resonance imaging (MRI) and three‐dimensional (3D) printing has been demonstrated to be a feasible approach for the creation of tissue matrices to aid in postmortem brain dissection. We aimed to extend this approach using hybrid structure light technology (visible and infrared) 3D scanning to generate brain models as a digital resource and operational tool for human neurodegenerative disease brain banks.MethodA consecutive series of 56 brains accessioned into the Glenn Biggs Institute Brain Bank were imaged using an EinScan H handheld 3D scanner. Five brains were selected for generation of tissue matrices, with infratentorial structures removed using 3D object post‐processing software tools. Matrices were printed using a Raise3D Pro2 printer and 1.75‐mm polylactic acid premium filament.ResultEach scan was approximately an hour to complete, including capture and alignment of a lateral and a medial surface scan for each brain. Raw scan files (DAT and BRAP‐PRJ) averaged 5.47 GB and 3D object files were 12,991 KB for 3MF and 18,067 KB for OBJ file types. For cases with tissue matrices, average print time was 42 hours with an average filament consumption of 338 g. Brain cutting with the tissue matrices was performed in a standardized manner, with superb control for section thickness and planar orientation compared to brains cut without a matrix.Conclusion3D scanning of postmortem autopsied brains is a simple and useful strategy to generate models with utility in guided tissue sectioning and storage (practice), surface area volumetric analysis (research) and virtual reality/augmented reality neuroanatomy training (education) for Alzheimer’s disease and related dementias.