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- Camporesi, Elena, et al.
(författare)
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Quantification of the trans-synaptic partners neurexin-neuroligin in CSF of neurodegenerative diseases by parallel reaction monitoring mass spectrometry
- 2022
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Ingår i: Ebiomedicine. - : Elsevier BV. - 2352-3964. ; 75
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Tidskriftsartikel (refereegranskat)abstract
- Background: Synaptic proteins are increasingly studied as biomarkers for synaptic dysfunction and loss, which are early and central events in Alzheimer's disease (AD) and strongly correlate with the degree of cognitive decline. In this study, we specifically investigated the synaptic binding partners neurexin (NRXN) and neuroligin (Nlgn) proteins, to assess their biomarker's potential. Methods: we developed a parallel reaction monitoring mass spectrometric method for the simultaneous quantification of NRXNs and Nlgns in cerebrospinal fluid (CSF) of neurodegenerative diseases, focusing on AD. Specifically, NRXN-1α, NRXN-1β, NRXN-2α, NRXN-3α and Nlgn1, Nlgn2, Nlgn3 and Nlgn4 proteins were targeted. Findings: The proteins were investigated in a clinical cohort including CSF from controls (n=22), mild cognitive impairment (MCI) due to AD (n=44), MCI due to other conditions (n=46), AD (n=77) and a group of non-AD dementia (n=28). No difference in levels of NRXNs and Nlgns was found between AD (both at dementia and MCI stages) or controls or the non-AD dementia group for any of the targeted proteins. NRXN and Nlgn proteins correlated strongly with each other, but only a weak correlation with the AD core biomarkers and the synaptic biomarkers neurogranin and growth-associated protein 43, was found, possibly reflecting different pathogenic processing at the synapse. Interpretation: we conclude that NRXN and Nlgn proteins do not represent suitable biomarkers for synaptic pathology in AD. The panel developed here could aid in future investigations of the potential involvement of NRXNs and Nlgns in synaptic dysfunction in other disorders of the central nervous system. Funding: a full list of funding can be found under the acknowledgments section. © 2021 The Author(s)
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| 2. |
- Lantero Rodriguez, Juan, et al.
(författare)
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Tau protein profiling in tauopathies: a human brain study
- 2024
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Ingår i: MOLECULAR NEURODEGENERATION. - 1750-1326. ; 19:1
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Tidskriftsartikel (refereegranskat)abstract
- Abnormal accumulation of misfolded and hyperphosphorylated tau protein in brain is the defining feature of several neurodegenerative diseases called tauopathies, including Alzheimer's disease (AD). In AD, this pathological change is reflected by highly specific cerebrospinal fluid (CSF) tau biomarkers, including both phosphorylated and non-phosphorylated variants. Interestingly, despite tau pathology being at the core of all tauopathies, CSF tau biomarkers remain unchanged in certain tauopathies, e.g., progressive supranuclear palsy (PSP), Pick's disease (PiD), and corticobasal neurodegeneration (CBD). To better understand commonalities and differences between tauopathies, we report a multiplex assay combining immunoprecipitation and high-resolution mass spectrometry capable of detecting and quantifying peptides from different tau protein isoforms as well as non-phosphorylated and phosphorylated peptides, including those carrying multiple phosphorylations. We investigated the tau proteoforms in soluble and insoluble fractions of brain tissue from subjects with autopsy-confirmed tauopathies, including sporadic AD (n = 10), PSP (n = 11), PiD (n = 10), and CBD (n = 10), and controls (n = 10). Our results demonstrate that non-phosphorylated tau profiles differ across tauopathies, generally showing high abundance of microtubule-binding region (MTBR)-containing peptides in insoluble protein fractions compared with controls; the AD group showed 12-72 times higher levels of MTBR-containing aggregates. Quantification of tau isoforms showed the 3R being more abundant in PiD and the 4R isoform being more abundant in CBD and PSP in the insoluble fraction. Twenty-three different phosphorylated peptides were quantified. Most phosphorylated peptides were measurable in all investigated tauopathies. All phosphorylated peptides were significantly increased in AD insoluble fraction. However, doubly and triply phosphorylated peptides were significantly increased in AD even in the soluble fraction. Results were replicated using a validation cohort comprising AD (n = 10), CBD (n = 10), and controls (n = 10). Our study demonstrates that abnormal levels of phosphorylation and aggregation do indeed occur in non-AD tauopathies, however, both appear pronouncedly increased in AD, becoming a distinctive characteristic of AD pathology.
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| 3. |
- Camporesi, Elena, et al.
(författare)
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Fluid Biomarkers for Synaptic Dysfunction and Loss
- 2020
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Ingår i: Biomarker Insights. - : SAGE Publications. - 1177-2719. ; 15
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Tidskriftsartikel (refereegranskat)abstract
- Synapses are the site for brain communication where information is transmitted between neurons and stored for memory formation. Synaptic degeneration is a global and early pathogenic event in neurodegenerative disorders with reduced levels of pre- and postsynaptic proteins being recognized as a core feature of Alzheimer's disease (AD) pathophysiology. Together with AD, other neurodegenerative and neurodevelopmental disorders show altered synaptic homeostasis as an important pathogenic event, and due to that, they are commonly referred to as synaptopathies. The exact mechanisms of synapse dysfunction in the different diseases are not well understood and their study would help understanding the pathogenic role of synaptic degeneration, as well as differences and commonalities among them and highlight candidate synaptic biomarkers for specific disorders. The assessment of synaptic proteins in cerebrospinal fluid (CSF), which can reflect synaptic dysfunction in patients with cognitive disorders, is a keen area of interest. Substantial research efforts are now directed toward the investigation of CSF synaptic pathology to improve the diagnosis of neurodegenerative disorders at an early stage as well as to monitor clinical progression. In this review, we will first summarize the pathological events that lead to synapse loss and then discuss the available data on established (eg, neurogranin, SNAP-25, synaptotagmin-1, GAP-43, and alpha-syn) and emerging (eg, synaptic vesicle glycoprotein 2A and neuronal pentraxins) CSF biomarkers for synapse dysfunction, while highlighting possible utilities, disease specificity, and technical challenges for their detection.
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| 4. |
- Nazir, Faisal Hayat, et al.
(författare)
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Expression and secretion of synaptic proteins during stem cell differentiation to cortical neurons.
- 2018
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Ingår i: Neurochemistry international. - : Elsevier BV. - 1872-9754 .- 0197-0186. ; 121, s. 38-49
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Tidskriftsartikel (refereegranskat)abstract
- Synaptic function and neurotransmitter release are regulated by specific proteins. Cortical neuronal differentiation of human induced pluripotent stem cells (hiPSC) provides an experimental model to obtain more information about synaptic development and physiology in vitro. In this study, expression and secretion of the synaptic proteins, neurogranin (NRGN), growth-associated protein-43 (GAP-43), synaptosomal-associated protein-25 (SNAP-25) and synaptotagmin-1 (SYT-1) were analyzed during cortical neuronal differentiation. Protein levels were measured in cells, modeling fetal cortical development and in cell-conditioned media which was used as a model of cerebrospinal fluid (CSF), respectively. Human iPSC-derived cortical neurons were maintained over a period of at least 150 days, which encompasses the different stages of neuronal development. The differentiation was divided into the following stages: hiPSC, neuro-progenitors, immature and mature cortical neurons. We show that NRGN was first expressed and secreted by neuro-progenitors while the maximum was reached in mature cortical neurons. GAP-43 was expressed and secreted first by neuro-progenitors and its expression increased markedly in immature cortical neurons. SYT-1 was expressed and secreted already by hiPSC but its expression and secretion peaked in mature neurons. SNAP-25 was first detected in neuro-progenitors and the expression and secretion increased gradually during neuronal stages reaching a maximum in mature neurons. The sensitive analytical techniques used to monitor the secretion of these synaptic proteins during cortical development make these data unique, since the secretion of these synaptic proteins has not been investigated before in such experimental models. The secretory profile of synaptic proteins, together with low release of intracellular content, implies that mature neurons actively secrete these synaptic proteins that previously have been associated with neurodegenerative disorders, including Alzheimer's disease. These data support further studies of human neuronal and synaptic development in vitro, and would potentially shed light on the mechanisms underlying altered concentrations of the proteins in bio-fluids in neurodegenerative diseases.
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