-
BioRxiv : the Preprint Server For... Jun 2024Multiple system atrophy (MSA) is rare, fast progressing, and fatal synucleinopathy with alpha-synuclein (α-syn) inclusions located within oligodendroglia called glial...
Multiple system atrophy (MSA) is rare, fast progressing, and fatal synucleinopathy with alpha-synuclein (α-syn) inclusions located within oligodendroglia called glial cytoplasmic inclusions (GCI). Along with GCI pathology there is severe demyelination, neurodegeneration, and neuroinflammation. In post-mortem tissue, there is significant infiltration of CD8+ T cells into the brain parenchyma, however their role in disease progression is unknown. To determine the role of CD8+ T cells, a modified AAV, Olig001-SYN, was used to selectively overexpress α-syn in oligodendrocytes modeling MSA in mice. Four weeks post transduction, we observed significant CD8+ T cell infiltration into the striatum of Olig001-SYN transduced mice recapitulating the CD8+ T cell infiltration observed in post-mortem tissue. To understand the role of CD8+ T cells, a CD8 knockout mice were transduced with Olig001-SYN. Six months post transduction into a mouse lacking CD8+ T cells, demyelination and neurodegeneration were unchanged. Four weeks post transduction, neuroinflammation and demyelination were enhanced in CD8 knockout mice compared to wild type controls. Applying unbiased spectral flow cytometry, CD103+, CD69+, CD44+, CXCR6+, CD8+ T cells were identified when α-syn was present in oligodendrocytes, suggesting the presence of tissue resident memory CD8+ T (Trm) cells during MSA disease progression. This study indicates that CD8+ T cells are not critical in driving MSA pathology but are needed to modulate the neuroinflammation and demyelination response.
PubMed: 38895456
DOI: 10.1101/2024.06.02.597035 -
BioRxiv : the Preprint Server For... Jun 2024Parkinson's disease (PD) and other α-synucleinopathies are characterized by the accumulation of α-synuclein (αS) pathology that can spread via the cell-to-cell...
Parkinson's disease (PD) and other α-synucleinopathies are characterized by the accumulation of α-synuclein (αS) pathology that can spread via the cell-to-cell transmission of αS aggregates. To better understand how various brain cells contribute to the spreading of αS pathology, we examined the metabolism of αS aggreges or pre-formed fibrils (PFFs) in neuronal and glial cells (microglia, astrocytes, and oligodendrocytes). In neurons, while the full-length αS rapidly disappeared following αS PFF uptake, truncated αS accumulated with a half-life of days rather than hours. Epitope mapping and fractionation studies indicate that αS PFF was truncated at the C-terminal region following uptake and remained insoluble/aggregated. In contrast, microglia and astrocytes rapidly metabolized αS PFF as the half-lives of αS PFF in these glial cells were <6 hours. Differential processing of αS by neurons was recapitulated in cell lines as differentiated CLU neuronal cell lines stably accumulate truncated αS while undifferentiated cells rapidly metabolize αS. Immunolocalization and subcellular fractionation studies show that internalized αS PFF is initially localized to endosomes followed by lysosomes. The lysosome is largely responsible for the degradation of internalized αS PFF as the inhibition of lysosomal function leads to the stabilization of αS in all cell types. Significantly, αS PFF causes lysosomal dysfunction in neurons. In summary, we show that neurons are inefficient in metabolizing internalized αS aggregates, partially because αS aggregates cause lysosomal dysfunction, potentially generating aggregation-prone truncated αS. In contrast, glial cells may protect neurons from αS aggregates by rapidly clearing αS aggregates.
PubMed: 38895363
DOI: 10.1101/2024.06.05.597615 -
Nutrients May 2024The rhizomes of Schott and Solander are widely used for treating amnesia in traditional Chinese medicine. In contrast, their leaves are usually discarded without their...
The rhizomes of Schott and Solander are widely used for treating amnesia in traditional Chinese medicine. In contrast, their leaves are usually discarded without their medicinal properties being known. Here, we found that the hot water extract of leaves improved cognition and tau pathology in model mice of frontotemporal dementia, similar to or even better than that of rhizomes. To explore the optimal method of processing, we made three preparations from dried leaves: hot water extract, extraction residue, and non-extracted simple crush powder. Among them, the simple crush powder had the strongest effect on tauopathy in mice. The crush powder also ameliorated Aβ and α-synuclein pathologies and restored cognition in mouse models of Alzheimer's disease and dementia with Lewy bodies. These findings suggest the potential of / leaves as a dietary source for dementia prevention and reveal that simple crushing is a better way to maximize their efficacy.
Topics: Animals; Plant Leaves; Acorus; Mice; Plant Extracts; Dementia; Disease Models, Animal; Cognition; Amyloid beta-Peptides; Male; Alzheimer Disease; tau Proteins
PubMed: 38892521
DOI: 10.3390/nu16111589 -
International Journal of Molecular... May 2024Alpha-synuclein seed amplification assays (αSyn-SAAs) have emerged as promising diagnostic tools for Parkinson's disease (PD) by detecting misfolded αSyn and...
Alpha-synuclein seed amplification assays (αSyn-SAAs) have emerged as promising diagnostic tools for Parkinson's disease (PD) by detecting misfolded αSyn and amplifying the signal through cyclic shaking and resting in vitro. Recently, our group and others have shown that multiple biospecimens, including CSF, skin, and submandibular glands (SMGs), can be used to seed the aggregation reaction and robustly distinguish between patients with PD and non-disease controls. The ultrasensitivity of the assay affords the ability to detect minute quantities of αSyn in peripheral tissues, but it also produces various technical challenges of variability. To address the problem of variability, we present a high-yield αSyn protein purification protocol for the efficient production of monomers with a low propensity for self-aggregation. We expressed wild-type αSyn in BL21 , lysed the cells using osmotic shock, and isolated αSyn using acid precipitation and fast protein liquid chromatography (FPLC). Following purification, we optimized the ionic strength of the reaction buffer to distinguish the fluorescence maximum (Fmax) separation between disease and healthy control tissues for enhanced assay performance. Our protein purification protocol yielded high quantities of αSyn (average: 68.7 mg/mL per 1 L of culture) and showed highly precise and robust αSyn-SAA results using brain, skin, and SMGs with inter-lab validation.
Topics: alpha-Synuclein; Humans; Parkinson Disease; Osmolar Concentration; Reproducibility of Results; Escherichia coli
PubMed: 38892177
DOI: 10.3390/ijms25115988 -
Cell Death & Disease Jun 2024Alterations in the dopamine catabolic pathway are known to contribute to the degeneration of nigrostriatal neurons in Parkinson's disease (PD). The progressive cellular...
Alterations in the dopamine catabolic pathway are known to contribute to the degeneration of nigrostriatal neurons in Parkinson's disease (PD). The progressive cellular buildup of the highly reactive intermediate 3,4-dihydroxyphenylacetaldehye (DOPAL) generates protein cross-linking, oligomerization of the PD-linked αSynuclein (αSyn) and imbalance in protein quality control. In this scenario, the autophagic cargo sequestome-1 (SQSTM1/p62) emerges as a target of DOPAL-dependent oligomerization and accumulation in cytosolic clusters. Although DOPAL-induced oxidative stress and activation of the Nrf2 pathway promote p62 expression, p62 oligomerization rather seems to be a consequence of direct DOPAL modification. DOPAL-induced p62 clusters are positive for ubiquitin and accumulate within lysosomal-related structures, likely affecting the autophagy-lysosomal functionality. Finally, p62 oligomerization and clustering is synergistically augmented by DOPAL-induced αSyn buildup. Hence, the substantial impact on p62 proteostasis caused by DOPAL appears of relevance for dopaminergic neurodegeneration, in which the progressive failure of degradative pathways and the deposition of proteins like αSyn, ubiquitin and p62 in inclusion bodies represent a major trait of PD pathology.
Topics: Animals; Humans; alpha-Synuclein; Autophagy; Dopamine; Dopaminergic Neurons; Lysosomes; Parkinson Disease; Sequestosome-1 Protein
PubMed: 38890356
DOI: 10.1038/s41419-024-06763-x -
Journal of Neural Transmission (Vienna,... Jun 2024Neurodegenerative disorders are typically featured by the occurrence of neuronal inclusions. In the case of Parkinson's disease (PD) these correspond to Lewy bodies...
In situ stoichiometry amounts of p62 and poly-ubiquitin exceed the increase of alpha-synuclein during degeneration of catecholamine cells induced by autophagy inhibition in vitro.
Neurodegenerative disorders are typically featured by the occurrence of neuronal inclusions. In the case of Parkinson's disease (PD) these correspond to Lewy bodies (LBs), which are routinely defined as proteinaceous inclusions composed of alpha-synuclein (alpha-syn). In turn, alpha-syn is considered to be the key protein in producing PD and fostering its progression. Recent studies challenged such a concept and emphasized the occurrence of other proteins such as p62 and poly-ubiquitin (Poly-ub) in the composition of LBs, which are also composed of large amounts of tubulo-vesicular structures. All these components, which accumulate within the cytosol of affected neurons in PD, may be the consequence of a dysfunction of major clearing pathways. In fact, autophagy-related systems are constantly impaired in inherited PD and genetic models of PD. The present study was designed to validate whether a pharmacological inhibition of autophagy within catecholamine cells produces cell damage and accumulation of specific proteins and tubulo-vesicular structures. The stoichiometry counts of single proteins, which accumulate within catecholamine neurons was carried out along with the area of tubulo-vesicular structures. In these experimental conditions p62 and Poly-ub accumulation exceeded at large the amounts of alpha-syn. In those areas where Poly-ub and p62 were highly expressed, tubulo-vesicular structures were highly represented compared with surrounding cytosol. The present study confirms new vistas about LBs composition and lends substance to the scenario that autophagy inhibition rather than a single protein dysfunction as key determinant of PD.
PubMed: 38890195
DOI: 10.1007/s00702-024-02795-x -
Current Biology : CB Jun 2024Nonhuman primates (NHPs) are indispensable animal models by virtue of the continuity of behavioral repertoires across primates, including humans. However, behavioral...
Nonhuman primates (NHPs) are indispensable animal models by virtue of the continuity of behavioral repertoires across primates, including humans. However, behavioral assessment at the laboratory level has so far been limited. Employing the application of three-dimensional (3D) pose estimation and the optimal integration of subsequent analytic methodologies, we demonstrate that our artificial intelligence (AI)-based approach has successfully deciphered the ethological, cognitive, and pathological traits of common marmosets from their natural behaviors. By applying multiple deep neural networks trained with large-scale datasets, we established an evaluation system that could reconstruct and estimate the 3D poses of the marmosets, a small NHP that is suitable for analyzing complex natural behaviors in laboratory setups. We further developed downstream analytic methodologies to quantify a variety of behavioral parameters beyond motion kinematics. We revealed the distinct parental roles of male and female marmosets through automated detections of food-sharing behaviors using a spatial-temporal filter on 3D poses. Employing a recurrent neural network to analyze 3D pose time series data during social interactions, we additionally discovered that marmosets adjusted their behaviors based on others' internal state, which is not directly observable but can be inferred from the sequence of others' actions. Moreover, a fully unsupervised approach enabled us to detect progressively appearing symptomatic behaviors over a year in a Parkinson's disease model. The high-throughput and versatile nature of an AI-driven approach to analyze natural behaviors will open a new avenue for neuroscience research dealing with big-data analyses of social and pathophysiological behaviors in NHPs.
PubMed: 38889723
DOI: 10.1016/j.cub.2024.05.033 -
Acta Neuropathologica Communications Jun 2024A link between chronic stress and Parkinson's disease (PD) pathogenesis is emerging. Ample evidence demonstrates that the presynaptic neuronal protein alpha-synuclein...
A link between chronic stress and Parkinson's disease (PD) pathogenesis is emerging. Ample evidence demonstrates that the presynaptic neuronal protein alpha-synuclein (asyn) is closely tied to PD pathogenesis. However, it is not known whether stress system dysfunction is present in PD, if asyn is involved, and if, together, they contribute to neurodegeneration. To address these questions, we assess stress axis function in transgenic rats overexpressing full-length wildtype human asyn (asyn BAC rats) and perform multi-level stress and PD phenotyping following chronic corticosterone administration. Stress signaling, namely corticotropin-releasing factor, glucocorticoid and mineralocorticoid receptor gene expression, is also examined in post-mortem PD patient brains. Overexpression of human wildtype asyn leads to HPA axis dysregulation in rats, while chronic corticosterone administration significantly aggravates nigrostriatal degeneration, serine129 phosphorylated asyn (pS129) expression and neuroinflammation, leading to phenoconversion from a prodromal to an overt motor PD phenotype. Interestingly, chronic corticosterone in asyn BAC rats induces a robust, twofold increase in pS129 expression in the hypothalamus, the master regulator of the stress response, while the hippocampus, both a regulator and a target of the stress response, also demonstrates elevated pS129 asyn levels and altered markers of stress signalling. Finally, defective hippocampal stress signalling is mirrored in human PD brains and correlates with asyn expression levels. Taken together, our results link brain stress system dysregulation with asyn and provide evidence that elevated circulating glucocorticoids can contribute to asyn-induced neurodegeneration, ultimately triggering phenoconversion from prodromal to overt PD.
Topics: alpha-Synuclein; Animals; Parkinson Disease; Humans; Rats, Transgenic; Rats; Stress, Psychological; Male; Corticosterone; Brain; Hypothalamo-Hypophyseal System; Female; Pituitary-Adrenal System
PubMed: 38886854
DOI: 10.1186/s40478-024-01797-w -
Cell Death Discovery Jun 2024Since the identification of vacuolar protein sorting (VPS) 35, as a causative molecule for familial Parkinson's disease (PD), retromer-mediated endosomal machinery has...
Since the identification of vacuolar protein sorting (VPS) 35, as a causative molecule for familial Parkinson's disease (PD), retromer-mediated endosomal machinery has been a rising factor in the pathogenesis of the disease. The retromer complex cooperates with sorting nexin (SNX) dimer and DNAJC13, another causal molecule in PD, to transport cargoes from endosomes to the trans-Golgi network, and is also involved in mitochondrial dynamics and autophagy. Retromer dysfunction may induce neuronal death leading to PD via several biological cascades, including misfolded, insoluble α-synuclein (aS) accumulation and mitochondrial dysfunction; however, the detailed mechanisms remain poorly understood. In this study, we showed that the stagnation of retromer-mediated retrograde transport consistently occurs in different PD-mimetic conditions, i.e., overexpression of PD-linked mutant DNAJC13, excess aS induction, or toxin-induced mitochondrial dysfunction. Mechanistically, DNAJC13 was found to be involved in clathrin-dependent retromer transport as a functional modulator of SNX1 together with heat shock cognate 70 kDa protein (Hsc70), which was controlled by the binding and dissociation of DNAJC13 and SNX1 in an Hsc70 activity-dependent manner. In addition, excess amount of aS decreased the interaction between SNX1 and VPS35, the core component of retromer. Furthermore, R33, a pharmacological retromer chaperone, reduced insoluble aS and mitigated rotenone-induced neuronal apoptosis. These findings suggest that retrograde transport regulated by SNX1-retromer may be profoundly involved in the pathogenesis of PD and is a potential target for disease-modifying therapy for the disease.
PubMed: 38886344
DOI: 10.1038/s41420-024-02062-8 -
Neurobiology of Disease Jun 2024Substantial work has been devoted to better understand the contribution of the myriad of genes that may underly the development of Parkinson's disease (PD) and their...
Substantial work has been devoted to better understand the contribution of the myriad of genes that may underly the development of Parkinson's disease (PD) and their role in disease etiology. The small GTPase Ras-like without CAAX2 (RIT2) is one such genetic risk factor, with one single nucleotide polymorphism in the RIT2 locus, rs12456492, having been associated with PD risk in multiple populations. While RIT2 has previously been shown to influence signaling pathways, dopamine transporter trafficking, and LRRK2 activity, its cellular function remains unclear. In the current study, we have situated RIT2 to be upstream of various diverse processes associated with PD. In cellular models, we have shown that RIT2 is necessary for activity-dependent changes in the expression of genes related to the autophagy-lysosomal pathway (ALP) by regulating the nuclear translocation of MiT/TFE3-family transcription factors. RIT2 is also associated with lysosomes and can regulate autophagic flux and clearance by regulating lysosomal hydrolase expression and activity. Interestingly, upregulation of RIT2 can augment ALP flux and protect against α-synuclein aggregation in cortical neurons. Taken together, the present study suggests that RIT2 can regulates gene expression upstream of ALP function and that enhancing RIT2 activity may provide therapeutic benefit in PD.
PubMed: 38885848
DOI: 10.1016/j.nbd.2024.106568