Dataset Information

Development of a novel method for the quantification of tyrosine 39 phosphorylated α- and β-synuclein in human cerebrospinal fluid.

ABSTRACT:

Background

Parkinson's disease (PD) is the second most prevalent neurodegenerative disorder. Biomarkers that can help monitor the progression of PD or response to disease-modifying agents will be invaluable in making appropriate therapeutic decisions. Further, biomarkers that could be used to distinguish PD from other related disorders with PD-like symptoms will be useful for accurate diagnosis and treatment. C-Abl tyrosine kinase is activated in PD resulting in increased phosphorylation of the tyrosine residue at position 39 (Y39) of α-synuclein (α-syn) (pY39 α-syn), which contributes to the death of dopaminergic neurons. Because pY39 α-syn may be pathogenic, monitoring pY39 α-syn could allow us to diagnose presymptomatic PD and help monitor disease progression and response to treatment. We sought to investigate if increased phosphorylation of pY39 α-syn can be detected in the cerebrospinal fluid (CSF) of PD patients by targeted mass spectrometry.

Methods

Here, we report a two-step enrichment method in which phosphotyrosine peptides were first enriched with an anti-phosphotyrosine antibody followed by a second round of enrichment by titanium dioxide (TiO₂) beads to detect EGVLpYVGSK sequence derived from tyrosine 39 region of α- and β-synuclein (αβ-syn). Accurate quantification was achieved by adding a synthetic heavy version of pY39 αβ-syn peptide before enzymatic digestion.

Results

Using the developed enrichment methods and optimized parallel reaction monitoring (PRM) assays, we detected pY39 αβ-syn peptide in human CSF and demonstrated that the ratio of pY39 αβ-syn to Y39 αβ-syn was significantly increased in the CSF of patients with PD.

Conclusions

We anticipate that this optimized two-step enrichment-based PRM detection method will help monitor c-Abl activation in PD patients and can also be used to quantify other phosphotyrosine peptides of low abundance in biological samples.

SUBMITTER: Na CH

PROVIDER: S-EPMC7197159 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Development of a novel method for the quantification of tyrosine 39 phosphorylated α- and β-synuclein in human cerebrospinal fluid.

Na Chan Hyun CH Sathe Gajanan G Rosenthal Liana S LS Moghekar Abhay R AR Dawson Valina L VL Dawson Ted M TM Pandey Akhilesh A

Clinical proteomics 20200504

<h4>Background</h4>Parkinson's disease (PD) is the second most prevalent neurodegenerative disorder. Biomarkers that can help monitor the progression of PD or response to disease-modifying agents will be invaluable in making appropriate therapeutic decisions. Further, biomarkers that could be used to distinguish PD from other related disorders with PD-like symptoms will be useful for accurate diagnosis and treatment. C-Abl tyrosine kinase is activated in PD resulting in increased phosphorylation ...[more]

PMID: 32390785

Similar Datasets

Project description:Parkinson’s disease (PD) is the second most prevalent neurodegenerative disorder caused by dopaminergic neuronal deaths. For a proper treatment of PD, biomarkers that would enable us to monitor disease progression or responses to a disease-modifying agent, or that can be used as a presymptomatic marker are critical. In addition, a biomarker that could be used to distinguish between the various diseases that manifest with PD-like symptoms would greatly enhance patient care and management of future clinical trials. Previous research indicates that c-Abl is overactive in PD patients resulting in an increased phosphorylation of the tyrosine 39 residue of alpha-synuclein (a-syn) (pY39 a-syn) and eventually dopaminergic neuronal death via a-syn aggregation. For this reason, monitoring pY39 a-syn will enable us to diagnose presymptomatic PD, monitoring disease progression and monitoring the response disease-modifying agents. We hypothesized that this increased phosphorylation on Y39 of a-syn (pY39 a-syn) will be reflected in the cerebrospinal fluid (CSF) of PD patients and monitoring pY39 a-syn level in CSF will enable us to monitor pY39 a-syn level in the brain. Mass spectrometry has been widely used for the detection of phosphorylated peptides using parallel reaction monitoring (PRM) and we utilized the PRM mass spectrometry for the detection of pY39 a-syn. However, pY39 a-syn was not detected even after immunoprecipitation of a-syn, phosphopeptide enrichment or phosphotyrosine peptide enrichment from a practical volume. For this reason, we have developed a two-step enrichment method in which pY39 a-syn was first enriched with an anti-phosphotyrosine antibody followed by a further enrichment of phosphopeptides with titanium oxide (TiO2) beads to remove non-phosphopeptides. Accurate quantification was obtained by including a synthetic pY39 a-syn peptide labeled with heavy lysine that was added before an enzyme digestion. To detect pY39 α-syn peptide in CSF lower than 10 femtomolar concentration, experimental parameters were optimized. Comparison of pY39 a-syn to total a-syn in CSF from PD patients and controls reveals that pY39 a-syn levels are significantly elevated in the CSF of PD patient versus controls. This optimized two-step enrichment PRM detection method may be of value as a biomarker to monitor c-Abl activation in PD patients for future diagnostic studies as well as a pharmacodynamic marker for c-Abl therapeutic trials in PD. Furthermore, this developed method can be applicable to quantifying other phosphotyrosine peptides with low abundance in biological samples.

Project description:Several studies have confirmed the α-synuclein real-time quaking-induced conversion (RT-QuIC) assay to have high sensitivity and specificity for Parkinson's disease. However, whether the assay can be used as a robust, quantitative measure to monitor disease progression, stratify different synucleinopathies and predict disease conversion in patients with idiopathic REM sleep behaviour disorder remains undetermined. The aim of this study was to assess the diagnostic value of CSF α-synuclein RT-QuIC quantitative parameters in regard to disease progression, stratification and conversion in synucleinopathies. We performed α-synuclein RT-QuIC in the CSF samples from 74 Parkinson's disease, 24 multiple system atrophy and 45 idiopathic REM sleep behaviour disorder patients alongside 55 healthy controls, analysing quantitative assay parameters in relation to clinical data. α-Synuclein RT-QuIC showed 89% sensitivity and 96% specificity for Parkinson's disease. There was no correlation between RT-QuIC quantitative parameters and Parkinson's disease clinical scores (e.g. Unified Parkinson's Disease Rating Scale motor), but RT-QuIC positivity and some quantitative parameters (e.g. Vmax) differed across the different phenotype clusters. RT-QuIC parameters also added value alongside standard clinical data in diagnosing Parkinson's disease. The sensitivity in multiple system atrophy was 75%, and CSF samples showed longer T50 and lower Vmax compared to Parkinson's disease. All RT-QuIC parameters correlated with worse clinical progression of multiple system atrophy (e.g. change in Unified Multiple System Atrophy Rating Scale). The overall sensitivity in idiopathic REM sleep behaviour disorder was 64%. In three of the four longitudinally followed idiopathic REM sleep behaviour disorder cohorts, we found around 90% sensitivity, but in one sample (DeNoPa) diagnosing idiopathic REM sleep behaviour disorder earlier from the community cases, this was much lower at 39%. During follow-up, 14 of 45 (31%) idiopathic REM sleep behaviour disorder patients converted to synucleinopathy with 9/14 (64%) of convertors showing baseline RT-QuIC positivity. In summary, our results showed that α-synuclein RT-QuIC adds value in diagnosing Parkinson's disease and may provide a way to distinguish variations within Parkinson's disease phenotype. However, the quantitative parameters did not correlate with disease severity in Parkinson's disease. The assay distinguished multiple system atrophy patients from Parkinson's disease patients and in contrast to Parkinson's disease, the quantitative parameters correlated with disease progression of multiple system atrophy. Our results also provided further evidence for α-synuclein RT-QuIC having potential as an early biomarker detecting synucleinopathy in idiopathic REM sleep behaviour disorder patients prior to conversion. Further analysis of longitudinally followed idiopathic REM sleep behaviour disorder patients is needed to better understand the relationship between α-synuclein RT-QuIC signature and the progression from prodromal to different synucleinopathies.

Project description:α-Synuclein (αSyn) is a major constituent of proteinaceous aggregates in neurodegenerative diseases such as Parkinson's disease (PD) and a potential biomarker candidate for diagnosis and treatment effects. However, studies about αSyn in cerebrospinal fluid (CSF) in diseases are inconsistent and mainly based on immunological assays. Quantitative information about β-synuclein (βSyn) and γ-synuclein (γSyn) in CSF is not available.Here, we present an alternative method for the simultaneous quantification of αSyn, βSyn and γSyn in CSF by multiple reaction monitoring (MRM) with a high sequence coverage (70%) of αSyn to validate previous, ELISA-based results and characterize synucleins in CSF in more detail.The MRM has high sensitivity in the low pg/ml range (3-30pg/ml full-length αSyn) using 200 μl CSF. A high portion of CSF αSyn is present in the N-terminally acetylated form and the concentration of unmodified peptides in the nonamyloid component region is about 40% lower than in the N-terminal region. Synuclein concentrations show a high correlation with each other in CSF (r>0.80) and in contrast to αSyn and γSyn, βSyn is not affected by blood contamination. CSF αSyn, βSyn and γSyn concentrations were increased in Alzheimer's and Creutzfeldt-Jakob disease but not altered in PD, PD dementia (PDD), Lewy body dementia and atypical parkinsonian syndromes. The ratio βSyn/αSyn was increased in PDD (1.49 ± 0.38, p < 0.05) compared with PD (1.11 ± 0.26) and controls (1.15 ± 0.28). βSyn shows a high correlation with CSF tau concentrations (r = 0.86, p < 0.0001, n = 125).In conclusion, we could not confirm previous observations of reduced αSyn in PD and our results indicate that CSF synuclein concentrations are rather general markers of synaptic degeneration than specific for synucleinopathies. βsyn is an attractive biomarker candidate that might be used as an alternative to or in combination with tau in AD and CJD diagnosis and in combination with αSyn it is a biomarker candidate for PDD.

Dataset Information

Development of a novel method for the quantification of tyrosine 39 phosphorylated α- and β-synuclein in human cerebrospinal fluid.

Background

Methods

Results

Conclusions

Publications

Development of a novel method for the quantification of tyrosine 39 phosphorylated α- and β-synuclein in human cerebrospinal fluid.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets