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Tissue transglutaminase-induced aggregation of alpha-synuclein: Implications for Lewy body formation in Parkinson's disease and dementia with Lewy bodies.

ABSTRACT: Proteinaceous aggregates containing alpha-synuclein represent a feature of neurodegenerative disorders such as Parkinson's disease, dementia with Lewy bodies, and multiple system atrophy. Despite extensive research, the mechanisms underlying alpha-synuclein aggregation remain elusive. Previously, tissue transglutaminase (tTGase) was found to contribute to the generation of aggregates by cross-linking pathogenic substrate proteins in Huntington's and Alzheimer's diseases. In this article, the role of tTGase in the formation of alpha-synuclein aggregates was investigated. Purified tTGase catalyzed alpha-synuclein cross-linking, leading to the formation of high molecular weight aggregates in vitro, and overexpression of tTGase resulted in the formation of detergent-insoluble alpha-synuclein aggregates in cellular models. Immunocytochemical studies demonstrated the presence of alpha-synuclein-positive cytoplasmic inclusions in 8% of tTGase-expressing cells. The formation of these aggregates was significantly augmented by the calcium ionophore and prevented by the inhibitor cystamine. Immunohistochemical studies on postmortem brain tissue confirmed the presence of transglutaminase-catalyzed epsilon (gamma-glutamyl)lysine cross-links in the halo of Lewy bodies in Parkinson's disease and dementia with Lewy bodies, colocalizing with alpha-synuclein. These findings, taken together, suggest that tTGase activity leads to alpha-synuclein aggregation to form Lewy bodies and perhaps contributes to neurodegeneration.

SUBMITTER: Junn E

PROVIDER: S-EPMC149956 | biostudies-literature | 2003 Feb

REPOSITORIES: biostudies-literature

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Tissue transglutaminase-induced aggregation of alpha-synuclein: Implications for Lewy body formation in Parkinson's disease and dementia with Lewy bodies.

Junn Eunsung E Ronchetti Ruben D RD Quezado Martha M MM Kim Soo-Youl SY Mouradian M Maral MM

Proceedings of the National Academy of Sciences of the United States of America 20030207 4

Proteinaceous aggregates containing alpha-synuclein represent a feature of neurodegenerative disorders such as Parkinson's disease, dementia with Lewy bodies, and multiple system atrophy. Despite extensive research, the mechanisms underlying alpha-synuclein aggregation remain elusive. Previously, tissue transglutaminase (tTGase) was found to contribute to the generation of aggregates by cross-linking pathogenic substrate proteins in Huntington's and Alzheimer's diseases. In this article, the rol ...[more]

PMID: 12576551

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Project description:Dementia with Lewy bodies is characterized by the accumulation of Lewy bodies and Lewy neurites in the CNS, both of which are composed mainly of aggregated α-synuclein phosphorylated at Ser129. Although phosphorylated α-synuclein is believed to exert toxic effects at the synapse in dementia with Lewy bodies and other α-synucleinopathies, direct evidence for the precise synaptic localization has been difficult to achieve due to the lack of adequate optical microscopic resolution to study human synapses. In the present study we applied array tomography, a microscopy technique that combines ultrathin sectioning of tissue with immunofluorescence allowing precise identification of small structures, to quantitatively investigate the synaptic phosphorylated α-synuclein pathology in dementia with Lewy bodies. We performed array tomography on human brain samples from five patients with dementia with Lewy bodies, five patients with Alzheimer's disease and five healthy control subjects to analyse the presence of phosphorylated α-synuclein immunoreactivity at the synapse and their relationship with synapse size. Main analyses were performed in blocks from cingulate cortex and confirmed in blocks from the striatum of cases with dementia with Lewy bodies. A total of 1 318 700 single pre- or postsynaptic terminals were analysed. We found that phosphorylated α-synuclein is present exclusively in dementia with Lewy bodies cases, where it can be identified in the form of Lewy bodies, Lewy neurites and small aggregates (<0.16 µm3). Between 19% and 25% of phosphorylated α-synuclein deposits were found in presynaptic terminals mainly in the form of small aggregates. Synaptic terminals that co-localized with small aggregates of phosphorylated α-synuclein were significantly larger than those that did not. Finally, a gradient of phosphorylated α-synuclein aggregation in synapses (pre > pre + post > postsynaptic) was observed. These results indicate that phosphorylated α-synuclein is found at the presynaptic terminals of dementia with Lewy bodies cases mainly in the form of small phosphorylated α-synuclein aggregates that are associated with changes in synaptic morphology. Overall, our data support the notion that pathological phosphorylated α-synuclein may disrupt the structure and function of the synapse in dementia with Lewy bodies.

Project description:The clinicopathological heterogeneity in Lewy-body diseases (LBD) highlights the need for pathology-driven biomarkers in-vivo. Misfolded alpha-synuclein (α-Syn) is a lead candidate based on its crucial role in disease pathophysiology. Real-time quaking-induced conversion (RT-QuIC) analysis of CSF has recently shown high sensitivity and specificity for the detection of misfolded α-Syn in patients with Parkinson's disease (PD) and dementia with Lewy bodies (DLB). In this study we performed the CSF RT-QuIC assay in 236 PD and 49 DLB patients enriched for different genetic forms with mutations in GBA, parkin, PINK1, DJ1, and LRRK2. A subgroup of 100 PD patients was also analysed longitudinally. We correlated kinetic seeding parameters of RT-QuIC with genetic status and CSF protein levels of molecular pathways linked to α-Syn proteostasis. Overall, 85% of PD and 86% of DLB patients showed positive RT-QuIC α-Syn seeding activity. Seeding profiles were significantly associated with mutation status across the spectrum of genetic LBD. In PD patients, we detected positive α-Syn seeding in 93% of patients carrying severe GBA mutations, in 78% with LRRK2 mutations, in 59% carrying heterozygous mutations in recessive genes, and in none of those with bi-allelic mutations in recessive genes. Among PD patients, those with severe GBA mutations showed the highest seeding activity based on RT-QuIC kinetic parameters and the highest proportion of samples with 4 out of 4 positive replicates. In DLB patients, 100% with GBA mutations showed positive α-Syn seeding compared to 79% of wildtype DLB. Moreover, we found an association between α-Syn seeding activity and reduced CSF levels of proteins linked to α-Syn proteostasis, specifically lysosome-associated membrane glycoprotein 2 and neurosecretory protein VGF.These findings highlight the value of α-Syn seeding activity as an in-vivo marker of Lewy-body pathology and support its use for patient stratification in clinical trials targeting α-Syn.

Project description:BackgroundThe objective of this study was to investigate the discriminating value of a range of CSF α-synuclein species for dementia with Lewy bodies compared with Alzheimer's disease, PD, and cognitively normal controls.MethodsWe applied our recently published enzyme-linked immunosorbent assays to measure the CSF levels of total α-synuclein, oligomeric α-synuclein, and phosphorylated α-synuclein in dementia with Lewy bodies (n = 42), Alzheimer's disease (n = 39), PD (n = 46), and controls (n = 78). General linear models corrected for age and sex were performed to assess differences in α-synuclein levels between groups. We used backward-elimination logistic regression analysis to investigate the combined discriminating value of the different CSF α-synuclein species and Alzheimer's disease biomarkers.ResultsCSF levels of total α-synuclein were lower in dementia with Lewy bodies and PD compared with Alzheimer's disease as well as controls (P < 0.001). In contrast, CSF levels of oligomeric α-synuclein were higher in dementia with Lewy bodies and PD compared with Alzheimer's disease (P < 0.05) and controls (P < 0.001). No group differences were found for phosphorylated α-synuclein. In dementia with Lewy bodies and PD, CSF total α-synuclein levels positively correlated with tau and phosphorylated tau (both r > 0.40, P < 0.01), but not with amyloid-β1-42 . The optimal combination to differentiate dementia with Lewy bodies from controls consisted of amyloid-β1-42 , tau, total α-synuclein, oligomeric α-synuclein, age, and sex (AUC, 0.90). To differentiate dementia with Lewy bodies from Alzheimer's disease, the combination of tau and oligomeric α-synuclein resulted in an AUC of 0.83. CSF α-synuclein species do not contribute to the differentiation of dementia with Lewy bodies from PD.ConclusionsCSF α-synuclein species could be useful as part of a biomarker panel for dementia with Lewy bodies. Evaluating both oligomeric α-synuclein and total α-synuclein in CSF helps in the diagnosis of dementia with Lewy bodies. © 2018 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.

Project description:Alpha-synuclein (aSyn) pathology is present in approximately 50% of Alzheimer's disease (AD) cases at autopsy and might impact the age-of-onset and disease progression in AD. Here, we aimed to determine whether tau and aSyn profiles differ between AD cases with Lewy bodies (AD-LB), pure AD and Parkinson's disease with dementia (PDD) cases using epitope-, post-translational modification- (PTM) and isoform-specific tau and aSyn antibody panels spanning from the N- to C-terminus. We included the middle temporal gyrus (MTG) and amygdala (AMY) of clinically diagnosed and pathologically confirmed cases and performed dot blotting, western blotting and immunohistochemistry combined with quantitative and morphological analyses. All investigated phospho-tau (pTau) species, except pT181, were upregulated in AD-LB and AD cases compared to PDD and control cases, but no significant differences were observed between AD-LB and AD subjects. In addition, tau antibodies targeting the proline-rich regions and C-terminus showed preferential binding to AD-LB and AD brain homogenates. Antibodies targeting C-terminal aSyn epitopes and pS129 aSyn showed stronger binding to AD-LB and PDD cases compared to AD and control cases. Two pTau species (pS198 and pS396) were specifically detected in the soluble protein fractions of AD-LB and AD subjects, indicative of early involvement of these PTMs in the multimerization process of tau. Other phospho-variants for both tau (pT212/S214, pT231 and pS422) and aSyn (pS129) were only detected in the insoluble protein fraction of AD-LB/AD and AD-LB/PDD cases, respectively. aSyn load was higher in the AMY of AD-LB cases compared to PDD cases, suggesting aggravated aSyn pathology under the presence of AD pathology, while tau load was similar between AD-LB and AD cases. Co-localization of pTau and aSyn could be observed within astrocytes of AD-LB cases within the MTG. These findings highlight a unique pathological signature for AD-LB cases compared to pure AD and PDD cases.

Dataset Information

Tissue transglutaminase-induced aggregation of alpha-synuclein: Implications for Lewy body formation in Parkinson's disease and dementia with Lewy bodies.

Publications

Tissue transglutaminase-induced aggregation of alpha-synuclein: Implications for Lewy body formation in Parkinson's disease and dementia with Lewy bodies.

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