Dynamic nanoclustering of synaptic proteins in health and disease: an examination of pre- and post-synaptic protein mobility in cell-to-cell communication

Abstract Background There is an urgent need for objective markers of Alzheimer’s disease (AD)-related cognitive impairment in people with Down syndrome (DS) to improve diagnosis, monitor disease progression, and assess response to disease-modifying therapies. Previously, GluA4 and neuronal pentraxin 2 (NPTX2) showed limited potential as cerebrospinal fluid (CSF) markers of cognitive impairment in adults with DS. Here, we compare the CSF profile of a panel of synaptic proteins (Calsyntenin-1, Neuroligin-2, Neurexin-2A, Neurexin-3A, Syntaxin-1B, Thy-1, VAMP-2) to that of NPTX2 and GluA4 in a large cohort of subjects with DS across the preclinical and clinical AD continuum and explore their correlation with cognitive impairment. Methods We quantified the synaptic panel proteins by selected reaction monitoring in CSF from 20 non-trisomic cognitively normal controls (mean age 44) and 80 adults with DS grouped according to clinical AD diagnosis (asymptomatic, prodromal AD or AD dementia). We used regression analyses to determine CSF changes across the AD continuum and explored correlations with age, global cognitive performance (CAMCOG), episodic memory (modified cued-recall test; mCRT) and CSF biomarkers, CSF Aβ42:40 ratio, CSF Aβ1-42, CSF p-tau, and CSF NFL. P values were adjusted for multiple testing. Results In adults with DS, VAMP-2 was the only synaptic protein to correlate with episodic memory (delayed recall adj.p = .04) and age (adj.p = .0008) and was the best correlate of CSF Aβ42:40 (adj.p = .0001), p-tau (adj.p < .0001), and NFL (adj.p < .0001). Compared to controls, mean VAMP-2 levels were lower in asymptomatic adults with DS only (adj.p = .02). CSF levels of Neurexin-3A, Thy-1, Neurexin-2A, Calysntenin-1, Neuroligin-2, GluA4, and Syntaxin-1B all strongly correlated with NPTX2 (p < .0001), which was the only synaptic protein to show reduced CSF levels in DS at all AD stages compared to controls (adj.p < .002). Conclusion These data show proof-of-concept for CSF VAMP-2 as a potential marker of synapse degeneration that correlates with CSF AD and axonal degeneration markers and cognitive performance.

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Cell-to-Cell Communication by Host-Released Extracellular Vesicles in the Gut: Implications in Health and Disease

International Journal of Molecular Sciences ◽

10.3390/ijms22042213 ◽

2021 ◽

Vol 22 (4) ◽

pp. 2213

Author(s):

Natalia Diaz-Garrido ◽

Cecilia Cordero ◽

Yenifer Olivo-Martinez ◽

Josefa Badia ◽

Laura Baldomà

Keyword(s):

Extracellular Vesicles ◽

Intestinal Mucosa ◽

Current Knowledge ◽

Cell Communication ◽

Bioactive Molecules ◽

Target Cells ◽

Immune Functions ◽

Intestinal Homeostasis ◽

General Terms ◽

Health And Disease

Communication between cells is crucial to preserve body homeostasis and health. Tightly controlled intercellular dialog is particularly relevant in the gut, where cells of the intestinal mucosa are constantly exposed to millions of microbes that have great impact on intestinal homeostasis by controlling barrier and immune functions. Recent knowledge involves extracellular vesicles (EVs) as mediators of such communication by transferring messenger bioactive molecules including proteins, lipids, and miRNAs between cells and tissues. The specific functions of EVs principally depend on the internal cargo, which upon delivery to target cells trigger signal events that modulate cellular functions. The vesicular cargo is greatly influenced by genetic, pathological, and environmental factors. This finding provides the basis for investigating potential clinical applications of EVs as therapeutic targets or diagnostic biomarkers. Here, we review current knowledge on the biogenesis and cargo composition of EVs in general terms. We then focus the attention to EVs released by cells of the intestinal mucosa and their impact on intestinal homeostasis in health and disease. We specifically highlight their role on epithelial barrier integrity, wound healing of epithelial cells, immunity, and microbiota shaping. Microbiota-derived EVs are not reviewed here.

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Protein synthesis in the dendrite

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2001.0887 ◽

2002 ◽

Vol 357 (1420) ◽

pp. 521-529 ◽

Cited By ~ 43

Author(s):

Shao Jun Tang ◽

Erin M. Schuman

Keyword(s):

Protein Synthesis ◽

Neural Plasticity ◽

Messenger Rna ◽

Mrna Translation ◽

Synaptic Activity ◽

Synaptic Proteins ◽

Local Source ◽

Synaptic Protein ◽

Specific Proteins ◽

Molecular Nature

In neurons, many proteins that are involved in the transduction of synaptic activity and the expression of neural plasticity are specifically localized at synapses. How these proteins are targeted is not clearly understood. One mechanism is synaptic protein synthesis. According to this idea, messenger RNA (mRNA) translation from the polyribosomes that are observed at the synaptic regions provides a local source of synaptic proteins. Although an increasing number of mRNA species has been detected in the dendrite, information about the synaptic synthesis of specific proteins in a physiological context is still limited. The physiological function of synaptic synthesis of specific proteins in synaptogenesis and neural plasticity expression remains to be shown. Experiments aimed at understanding the mechanisms and functions f synaptic protein synthesis might provide important information about the molecular nature of neural plasticity.

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Multiplexed Profiling of Single-cell Extracellular Vesicles Secretion

10.1101/459438 ◽

2018 ◽

Author(s):

Yahui Ji ◽

Dongyuan Qi ◽

Linmei Li ◽

Haoran Su ◽

Xiaojie Li ◽

...

Keyword(s):

Single Cell ◽

Cell Lines ◽

Extracellular Vesicles ◽

Single Cells ◽

Cell Communication ◽

Deep Understanding ◽

Surface Markers ◽

Cell Heterogeneity ◽

Health And Disease ◽

Cytokines Secretion

AbstractExtracellular vesicles (EVs) are important intercellular mediators regulating health and disease. Conventional EVs surface marker profiling, which was based on population measurements, masked the cell-to-cell heterogeneity in the quantity and phenotypes of EVs secretion. Herein, by using spatially patterned antibodies barcode, we realized multiplexed profiling of single-cell EVs secretion from more than 1000 single cells simultaneously. Applying this platform to profile human oral squamous cell carcinoma (OSCC) cell lines led to deep understanding of previously undifferentiated single cell heterogeneity underlying EVs secretion. Notably, we observed the decrement of certain EV phenotypes (e.g. CD63+EVs) were associated with the invasive feature of both OSCC cell lines and primary OSCC cells. We also realized multiplexed detection of EVs secretion and cytokines secretion simultaneously from the same single cells to investigate multidimensional spectrum of intercellular communications, from which we resolved three functional subgroups with distinct secretion profiles by visualized clustering. In particular, we found EVs secretion and cytokines secretion were generally dominated by different cell subgroups. The technology introduced here enables comprehensive evaluation of EVs secretion heterogeneity at single cell level, which may become an indispensable tool to complement current single cell analysis and EV research.SignificanceExtracellular vesicles (EVs) are cell derived nano-sized particles medicating cell-cell communication and transferring biology information molecules like nucleic acids to regulate human health and disease. Conventional methods for EV surface markers profiling can’t tell the differences in the quantity and phenotypes of EVs secretion between cells. To address this need, we developed a platform for profiling an array of surface markers on EVs from large numbers of single cells, enabling more comprehensive monitoring of cellular communications. Single cell EVs secretion assay led to previously unobserved cell heterogeneity underlying EVs secretion, which might open up new avenues for studying cell communication and cell microenvironment in both basic and clinical research.

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Proteomic Analysis of Brain Region and Sex-Specific Synaptic Protein Expression in the Adult Mouse Brain

Cells ◽

10.3390/cells9020313 ◽

2020 ◽

Vol 9 (2) ◽

pp. 313

Author(s):

Ute Distler ◽

Sven Schumann ◽

Hans-Georg Kesseler ◽

Rainer Pielot ◽

Karl-Heinz Smalla ◽

...

Keyword(s):

Brain Region ◽

Adult Mouse ◽

Autism Spectrum ◽

Synaptic Proteins ◽

Male And Female ◽

Proteomic Approach ◽

Wide Range ◽

Crucial Information ◽

Health And Disease ◽

Molecular Anatomy

Genetic disruption of synaptic proteins results in a whole variety of human neuropsychiatric disorders including intellectual disability, schizophrenia or autism spectrum disorder (ASD). In a wide range of these so-called synaptopathies a sex bias in prevalence and clinical course has been reported. Using an unbiased proteomic approach, we analyzed the proteome at the interaction site of the pre- and postsynaptic compartment, in the prefrontal cortex, hippocampus, striatum and cerebellum of male and female adult C57BL/6J mice. We were able to reveal a specific repertoire of synaptic proteins in different brain areas as it has been implied before. Additionally, we found a region-specific set of novel synaptic proteins differentially expressed between male and female individuals including the strong ASD candidates DDX3X, KMT2C, MYH10 and SET. Being the first comprehensive analysis of brain region-specific synaptic proteomes from male and female mice, our study provides crucial information on sex-specific differences in the molecular anatomy of the synapse. Our efforts should serve as a neurobiological framework to better understand the influence of sex on synapse biology in both health and disease.

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Trem2 Y38C Mutation and Loss of Trem2 Impairs Neuronal Synapses in Adult Mice

10.21203/rs.3.rs-33900/v1 ◽

2020 ◽

Author(s):

Vaishnavi S. Jadhav ◽

Peter BC. Lin ◽

Guixiang Xu ◽

Taylor Pennington ◽

Gonzalo Viana Di Prisco ◽

...

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Synaptic Plasticity ◽

Late Onset ◽

Synaptic Proteins ◽

Synaptic Protein ◽

Presenile Dementia ◽

Altered Expression ◽

Protein Levels

Abstract Background:Triggering receptor expressed on myeloid cells 2 (TREM2) is expressed in the brain exclusively on microglia and genetic variants are linked to neurodegenerative diseases including Alzheimer’s disease (AD), frontotemporal dementia (FTD) and NasuHakola Disease (NHD). The Trem2 variantR47H, confers substantially elevated risk of developing late onset Alzheimer’s disease, while NHD-linkedTrem2 variants like Y38Care associated with development of early onset dementia with white matter pathology. However, it is not known how these Trem2species predispose individuals to presenile dementia.Methods:To investigate if Trem2 Y38C or loss of Trem2 alters neuronal function, we generated a novel mouse model to introduce the NHD Trem2 Y38C variant in murine Trem2 using CRISPR/Cas9 technology. Trem2Y38/Y38C and Trem2-/-mice were assessed for Trem2 expression, differentially expressed genes, synaptic protein levels and synaptic plasticity using biochemical, electrophysiological and transcriptomic approaches.Results:While mice harboring Trem2 Y38C exhibited normal expression levels of Trem2, the pathological outcomes phenocopied Trem2-/- miceat 6 months. Transcriptomic analysis revealed altered expression of neuronal and oligodendrocytes/myelin genes. We observed regional decreases in synaptic protein levels, with the most affected synapses in the hippocampus. These alterations were associated with reduced synaptic plasticity. Conclusion:Our findings provide in vivo evidence that Trem2 Y38C disrupts normal TREM2 functions. Trem2Y38C/Y38Cand Trem2-/- mice demonstrated altered gene expression, changes in microglia morphology, loss of synaptic proteins and reduced hippocampal synaptic plasticity at 6 months in absence of any pathological triggers like tau or amyloid. This suggests TREM2 impacts neuronal functions and providesmolecular insights on the predisposition of individuals with TREM2 variants resulting in presenile dementia.

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Recent insights on principles of synaptic protein degradation

F1000Research ◽

10.12688/f1000research.10599.1 ◽

2017 ◽

Vol 6 ◽

pp. 675 ◽

Cited By ~ 14

Author(s):

Laurie D. Cohen ◽

Noam E. Ziv

Keyword(s):

Protein Degradation ◽

Life Cycles ◽

Synaptic Proteins ◽

Degradation Pathways ◽

Synaptic Protein ◽

Turnover Rates ◽

Complex Life Cycles ◽

Cellular Context ◽

Experimental Approaches ◽

And Function

Maintaining synaptic integrity and function depends on the continuous removal and degradation of aged or damaged proteins. Synaptic protein degradation has received considerable attention in the context of synaptic plasticity and growing interest in relation to neurodegenerative and other disorders. Conversely, less attention has been given to constitutive, ongoing synaptic protein degradation and the roles canonical degradation pathways play in these processes. Here we briefly review recent progress on this topic and new experimental approaches which have expedited such progress and highlight several emerging principles. These include the realization that synaptic proteins typically have unusually long lifetimes, as might be expected from the remote locations of most synaptic sites; the possibility that degradation pathways can change with time from synthesis, cellular context, and physiological input; and that degradation pathways, other than ubiquitin-proteasomal-mediated degradation, might play key roles in constitutive protein degradation at synaptic sites. Finally, we point to the importance of careful experimental design and sufficiently sensitive techniques for studying synaptic protein degradation, which bring into account their slow turnover rates and complex life cycles.

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Environmental Enrichment Rescues Social Behavioral Deficits and Synaptic Abnormalities in Pten Haploinsufficient Mice

Genes ◽

10.3390/genes12091366 ◽

2021 ◽

Vol 12 (9) ◽

pp. 1366

Author(s):

Amy E. Clipperton-Allen ◽

Angela Zhang ◽

Ori S. Cohen ◽

Damon Theron Page

Keyword(s):

Synaptic Plasticity ◽

Environmental Enrichment ◽

Repetitive Behavior ◽

Synaptic Proteins ◽

Protein Abundance ◽

Synaptic Protein ◽

Wild Type ◽

Neuronal Connectivity ◽

Behavioral Deficits ◽

Adult Mice

Pten germline haploinsufficient (Pten+/−) mice, which model macrocephaly/autism syndrome, show social and repetitive behavior deficits, early brain overgrowth, and cortical–subcortical hyperconnectivity. Previous work indicated that altered neuronal connectivity may be a substrate for behavioral deficits. We hypothesized that exposing Pten+/− mice to environmental enrichment after brain overgrowth has occurred may facilitate adaptation to abnormal “hard-wired” connectivity through enhancing synaptic plasticity. Thus, we reared Pten+/− mice and their wild-type littermates from weaning under either standard (4–5 mice per standard-sized cage, containing only bedding and nestlet) or enriched (9–10 mice per large-sized cage, containing objects for exploration and a running wheel, plus bedding and nestlet) conditions. Adult mice were tested on social and non-social assays in which Pten+/− mice display deficits. Environmental enrichment rescued sex-specific deficits in social behavior in Pten+/− mice and partially rescued increased repetitive behavior in Pten+/− males. We found that Pten+/− mice show increased excitatory and decreased inhibitory pre-synaptic proteins; this phenotype was also rescued by environmental enrichment. Together, our results indicate that environmental enrichment can rescue social behavioral deficits in Pten+/− mice, possibly through normalizing the excitatory synaptic protein abundance.

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Stitching the synapse: Cross-linking mass spectrometry into resolving synaptic protein interactions

Science Advances ◽

10.1126/sciadv.aax5783 ◽

2020 ◽

Vol 6 (8) ◽

pp. eaax5783 ◽

Cited By ~ 10

Author(s):

M. A. Gonzalez-Lozano ◽

F. Koopmans ◽

P. F. Sullivan ◽

J. Protze ◽

G. Krause ◽

...

Keyword(s):

Mass Spectrometry ◽

Protein Interactions ◽

Protein Complexes ◽

Conformational Dynamics ◽

Synaptic Proteins ◽

Cross Linking ◽

Synaptic Protein ◽

Protein Partners ◽

Associated Proteins ◽

Model Protein

Synaptic transmission is the predominant form of communication in the brain. It requires functionally specialized molecular machineries constituted by thousands of interacting synaptic proteins. Here, we made use of recent advances in cross-linking mass spectrometry (XL-MS) in combination with biochemical and computational approaches to reveal the architecture and assembly of synaptic protein complexes from mouse brain hippocampus and cerebellum. We obtained 11,999 unique lysine-lysine cross-links, comprising connections within and between 2362 proteins. This extensive collection was the basis to identify novel protein partners, to model protein conformational dynamics, and to delineate within and between protein interactions of main synaptic constituents, such as Camk2, the AMPA-type glutamate receptor, and associated proteins. Using XL-MS, we generated a protein interaction resource that we made easily accessible via a web-based platform (http://xlink.cncr.nl) to provide new entries into exploration of all protein interactions identified.

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Oligodendrocytes express synaptic proteins that modulate myelin sheath formation

Nature Communications ◽

10.1038/s41467-019-12059-y ◽

2019 ◽

Vol 10 (1) ◽

Cited By ~ 19

Author(s):

Alexandria N. Hughes ◽

Bruce Appel

Keyword(s):

Membrane Fusion ◽

Myelin Sheath ◽

Synaptic Vesicles ◽

Fusion Proteins ◽

Synaptic Proteins ◽

Synaptic Protein ◽

Site Location ◽

Myelin Sheaths ◽

Vesicular Release ◽

Sheath Formation

Abstract Vesicular release from neurons promotes myelin sheath growth on axons. Oligodendrocytes express proteins that allow dendrites to respond to vesicular release at synapses, suggesting that axon-myelin contacts use similar communication mechanisms as synapses to form myelin sheaths. To test this, we used fusion proteins to track synaptic vesicle localization and membrane fusion in zebrafish during developmental myelination and investigated expression and localization of PSD95, a dendritic post-synaptic protein, within oligodendrocytes. Synaptic vesicles accumulate and exocytose at ensheathment sites with variable patterning and most sheaths localize PSD95 with patterning similar to exocytosis site location. Disruption of candidate PDZ-binding transsynaptic adhesion proteins in oligodendrocytes cause variable effects on sheath length and number. One candidate, Cadm1b, localizes to myelin sheaths where both PDZ binding and extracellular adhesion to axons mediate sheath growth. Our work raises the possibility that axon-glial communication contributes to myelin plasticity, providing new targets for mechanistic unraveling of developmental myelination.

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