Publications by authors named "Ka Wan Li"

90 Publications

The proteome of granulovacuolar degeneration and neurofibrillary tangles in Alzheimer's disease.

Acta Neuropathol 2021 Mar 25;141(3):341-358. Epub 2021 Jan 25.

Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, VU University Amsterdam, Amsterdam, The Netherlands.

Granulovacuolar degeneration (GVD) is a common feature in Alzheimer's disease (AD). The occurrence of GVD is closely associated with that of neurofibrillary tangles (NFTs) and GVD is even considered to be a pre-NFT stage in the disease process of AD. Currently, the composition of GVD bodies, the mechanisms associated with GVD and how GVD exactly relates to NFTs is not well understood. By combining immunohistochemistry (IHC) and laser microdissection (LMD) we isolated neurons with GVD and those bearing tangles separately from human post-mortem AD hippocampus (n = 12) using their typical markers casein kinase (CK)1δ and phosphorylated tau (AT8). Control neurons were isolated from cognitively healthy cases (n = 12). 3000 neurons per sample were used for proteome analysis by label free LC-MS/MS. In total 2596 proteins were quantified across samples and a significant change in abundance of 115 proteins in GVD and 197 in tangle bearing neurons was observed compared to control neurons. With IHC the presence of PPIA, TOMM34, HSP70, CHMP1A, TPPP and VXN was confirmed in GVD containing neurons. We found multiple proteins localizing specifically to the GVD bodies, with VXN and TOMM34 being the most prominent new protein markers for GVD bodies. In general, protein groups related to protein folding, proteasomal function, the endolysosomal pathway, microtubule and cytoskeletal related function, RNA processing and glycolysis were found to be changed in GVD neurons. In addition to these protein groups, tangle bearing neurons show a decrease in ribosomal proteins, as well as in various proteins related to protein folding. This study, for the first time, provides a comprehensive human based quantitative assessment of protein abundances in GVD and tangle bearing neurons. In line with previous functional data showing that tau pathology induces GVD, our data support the model that GVD is part of a pre-NFT stage representing a phase in which proteostasis and cellular homeostasis is disrupted. Elucidating the molecular mechanisms and cellular processes affected in GVD and its relation to the presence of tau pathology is highly relevant for the identification of new drug targets for therapy.
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http://dx.doi.org/10.1007/s00401-020-02261-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7882576PMC
March 2021

Recent Developments in Data Independent Acquisition (DIA) Mass Spectrometry: Application of Quantitative Analysis of the Brain Proteome.

Front Mol Neurosci 2020 23;13:564446. Epub 2020 Dec 23.

Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, Faculty of Science, Vrije Universiteit Amsterdam, Amsterdam, Netherlands.

Mass spectrometry is the driving force behind current brain proteome analysis. In a typical proteomics approach, a protein isolate is digested into tryptic peptides and then analyzed by liquid chromatography-mass spectrometry. The recent advancements in data independent acquisition (DIA) mass spectrometry provide higher sensitivity and protein coverage than the classic data dependent acquisition. DIA cycles through a pre-defined set of peptide precursor isolation windows stepping through 400-1,200 m/z across the whole liquid chromatography gradient. All peptides within an isolation window are fragmented simultaneously and detected by tandem mass spectrometry. Peptides are identified by matching the ion peaks in a mass spectrum to a spectral library that contains information of the peptide fragment ions' pattern and its chromatography elution time. Currently, there are several reports on DIA in brain research, in particular the quantitative analysis of cellular and synaptic proteomes to reveal the spatial and/or temporal changes of proteins that underlie neuronal plasticity and disease mechanisms. Protocols in DIA are continuously improving in both acquisition and data analysis. The depth of analysis is currently approaching proteome-wide coverage, while maintaining high reproducibility in a stable and standardisable MS environment. DIA can be positioned as the method of choice for routine proteome analysis in basic brain research and clinical applications.
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http://dx.doi.org/10.3389/fnmol.2020.564446DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7793698PMC
December 2020

The endosomal protein sorting nexin 4 is a synaptic protein.

Sci Rep 2020 10 26;10(1):18239. Epub 2020 Oct 26.

Clinical Genetics, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, Amsterdam UMC Location VUmc, De Boelelaan 1085, 1081 HV, Amsterdam, The Netherlands.

Sorting nexin 4 (SNX4) is an evolutionary conserved protein that mediates recycling from endosomes back to the plasma membrane in yeast and mammalian cells. SNX4 is expressed in the brain. Altered protein levels are associated with Alzheimer's disease, but the neuronal localization and function of SNX4 have not been addressed. Using a new antibody, endogenous neuronal SNX4 co-localized with both early and recycling endosome markers, similar to the reported localization of SNX4 in non-neuronal cells. Neuronal SNX4 accumulated specifically in synaptic areas, with a predominant localization to presynaptic terminals. Acute depletion of neuronal SNX4 using independent short hairpin RNAs did not affect the levels of the transferrin receptor, a canonical SNX4 cargo. Quantitative mass spectrometry revealed that upon SNX4 knockdown the class of proteins involved in neurotransmission was the most dysregulated. This included integral membrane proteins at both the presynaptic and postsynaptic side of the synapse that participate in diverse synaptic processes such as synapse assembly, neurotransmission and the synaptic vesicle cycle. These data suggest that SNX4 is implicated in a variety of synaptic processes.
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http://dx.doi.org/10.1038/s41598-020-74694-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7588491PMC
October 2020

Aralar Sequesters GABA into Hyperactive Mitochondria, Causing Social Behavior Deficits.

Cell 2020 03;180(6):1178-1197.e20

Department of Fundamental Neurosciences, University of Lausanne, Lausanne 1005, Switzerland; University of Rome Tor Vergata, Department of Biomedicine and Prevention, Rome 00133, Italy. Electronic address:

Social impairment is frequently associated with mitochondrial dysfunction and altered neurotransmission. Although mitochondrial function is crucial for brain homeostasis, it remains unknown whether mitochondrial disruption contributes to social behavioral deficits. Here, we show that Drosophila mutants in the homolog of the human CYFIP1, a gene linked to autism and schizophrenia, exhibit mitochondrial hyperactivity and altered group behavior. We identify the regulation of GABA availability by mitochondrial activity as a biologically relevant mechanism and demonstrate its contribution to social behavior. Specifically, increased mitochondrial activity causes gamma aminobutyric acid (GABA) sequestration in the mitochondria, reducing GABAergic signaling and resulting in social deficits. Pharmacological and genetic manipulation of mitochondrial activity or GABA signaling corrects the observed abnormalities. We identify Aralar as the mitochondrial transporter that sequesters GABA upon increased mitochondrial activity. This study increases our understanding of how mitochondria modulate neuronal homeostasis and social behavior under physiopathological conditions.
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http://dx.doi.org/10.1016/j.cell.2020.02.044DOI Listing
March 2020

Glycine Receptor Complex Analysis Using Immunoprecipitation-Blue Native Gel Electrophoresis-Mass Spectrometry.

Proteomics 2020 02 6;20(3-4):e1900403. Epub 2020 Feb 6.

Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Vrije Universiteit, De Boelelaan 1085, 1081 HV, Amsterdam, The Netherlands.

The pentameric glycine receptor (GlyR), comprising the α1 and β subunits, is a major inhibitory ionotropic receptor in brainstem and spinal cord. GlyRs interact with gephyrin (GPHN), a scaffold protein that anchors the GlyR in the plasma membrane and enables it to form clusters in glycinergic postsynapses. Using an interaction proteomics approach, evidence of the ArfGEFs IQ motif and Sec7 domain 3 (IQSEC3) and IQ motif and Sec7 domain 2 (IQSEC2) as two novel synaptic proteins interacting with GlyR complexes is provided. When the affinity-isolated GlyR complexes are fractionated by blue native gel electrophoresis and characterized by mass spectrometry, GlyR α1β-GPHN appears as the most abundant complex with a molecular weight of ≈1 MDa, and GlyR α1β-GPHN-IQSEC3 as a minor protein complex of ≈1.2 MDa. A third GlyR α1β-GPHN-IQSEC2 complex exists at the lowest amount with a mass similar to the IQSEC3 containing complex. Using yeast two-hybrid it is demonstrated that IQSEC3 interacts with the GlyR complex by binding to the GPHN G domain at the N-terminal of the IQSEC3 IQ-like domain. The data provide direct evidence of the interaction of IQSEC3 with GlyR-GPHN complexes, underscoring a potential role of these ArfGEFs in the function of glycinergic synapses.
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http://dx.doi.org/10.1002/pmic.201900403DOI Listing
February 2020

Deficiency Impacts Hippocampal CA1 Neuronal Excitability, Dendritic Architecture, and Affects Spatial Learning.

Front Cell Neurosci 2019 25;13:465. Epub 2019 Oct 25.

Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, Vrije Universiteit, Amsterdam, Netherlands.

G-protein-coupled receptor 158 () is highly expressed in striatum, hippocampus and prefrontal cortex. It gained attention as it was implicated in physiological responses to stress and depression. Recently, has been shown to act as a pathway-specific synaptic organizer in the hippocampus, required for proper mossy fiber-CA3 neurocircuitry establishment, structure, and function. Although rodent expression is highest in CA3, considerable expression occurs in CA1 especially after the first postnatal month. Here, we combined hippocampal-dependent behavioral paradigms with subsequent electrophysiological and morphological analyses from the same group of mice to assess the effects of deficiency on CA1 physiology and function. We demonstrate deficits in spatial memory acquisition and retrieval in the Morris water maze paradigm, along with deficits in the acquisition of extinction memory in the passive avoidance test in KO mice. Electrophysiological recordings from CA1 pyramidal neurons revealed normal basal excitatory and inhibitory synaptic transmission, however, Schaffer collateral stimulation yielded dramatically reduced post-synaptic currents. Interestingly, intrinsic excitability of CA1 pyramidals was found increased, potentially acting as a compensatory mechanism to the reductions in Schaffer collateral-mediated drive. Both and , neurons deficient for or with lowered levels of exhibited robust reductions in dendritic architecture and complexity, i.e., reduced length, surface, bifurcations, and branching. This effect was localized in the apical but not basal dendrites of adult CA1 pyramidals, indicative of compartment-specific alterations. A significant positive correlation between spatial memory acquisition and extent of complexity of CA1 pyramidals was found. Taken together, we provide first evidence of significant disruptions in hippocampal CA1 neuronal dendritic architecture and physiology, driven by deficiency. Importantly, the hippocampal neuronal morphology deficits appear to support the impairments in spatial memory acquisition observed in KO mice.
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http://dx.doi.org/10.3389/fncel.2019.00465DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6843000PMC
October 2019

The Effects of Sindbis Viral Vectors on Neuronal Function.

Front Cell Neurosci 2019 8;13:362. Epub 2019 Aug 8.

Laboratory for Neuroregeneration, The Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Amsterdam, Netherlands.

Viral vectors are attractive tools to express genes in neurons. Transduction of neurons with a recombinant, replication-deficient Sindbis viral vector is a method of choice for studying the effects of short-term protein overexpression on neuronal function. However, to which extent Sindbis by itself may affect neurons is not fully understood. We assessed effects of neuronal transduction with a Sindbis viral vector on the transcriptome and proteome in organotypic hippocampal slice cultures, and analyzed the electrophysiological properties of individual CA1 neurons, at 24 h and 72 h after viral vector injection. Whereas Sindbis caused substantial gene expression alterations, changes at the protein level were less pronounced. Alterations in transcriptome and proteome were predominantly limited to proteins involved in mediating anti-viral innate immune responses. Sindbis transduction did not affect the intrinsic electrophysiological properties of individual neurons: the membrane potential and neuronal excitability were similar between transduced and non-transduced CA1 neurons up to 72 h after Sindbis injection. Synaptic currents also remained unchanged upon Sindbis transduction, unless slices were massively infected for 72 h. We conclude that Sindbis viral vectors at low transduction rates are suitable for studying short-term effects of a protein of interest on electrophysiological properties of neurons, but not for studies on the regulation of gene expression.
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http://dx.doi.org/10.3389/fncel.2019.00362DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6694438PMC
August 2019

The autism- and schizophrenia-associated protein CYFIP1 regulates bilateral brain connectivity and behaviour.

Nat Commun 2019 08 1;10(1):3454. Epub 2019 Aug 1.

Department of Fundamental Neurosciences, University of Lausanne, 1005, Lausanne, Switzerland.

Copy-number variants of the CYFIP1 gene in humans have been linked to autism spectrum disorders (ASD) and schizophrenia (SCZ), two neuropsychiatric disorders characterized by defects in brain connectivity. Here, we show that CYFIP1 plays an important role in brain functional connectivity and callosal functions. We find that Cyfip1-heterozygous mice have reduced functional connectivity and defects in white matter architecture, similar to phenotypes found in patients with ASD, SCZ and other neuropsychiatric disorders. Cyfip1-deficient mice also present decreased myelination in the callosal axons, altered presynaptic function, and impaired bilateral connectivity. Finally, Cyfip1 deficiency leads to abnormalities in motor coordination, sensorimotor gating and sensory perception, which are also known neuropsychiatric disorder-related symptoms. These results show that Cyfip1 haploinsufficiency compromises brain connectivity and function, which might explain its genetic association to neuropsychiatric disorders.
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http://dx.doi.org/10.1038/s41467-019-11203-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6672001PMC
August 2019

SALM1 controls synapse development by promoting F-actin/PIP2-dependent Neurexin clustering.

EMBO J 2019 09 1;38(17):e101289. Epub 2019 Aug 1.

Department of Clinical Genetics, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, VU University Amsterdam and VU Medical Center, Amsterdam, The Netherlands.

Synapse development requires spatiotemporally regulated recruitment of synaptic proteins. In this study, we describe a novel presynaptic mechanism of cis-regulated oligomerization of adhesion molecules that controls synaptogenesis. We identified synaptic adhesion-like molecule 1 (SALM1) as a constituent of the proposed presynaptic Munc18/CASK/Mint1/Lin7b organizer complex. SALM1 preferentially localized to presynaptic compartments of excitatory hippocampal neurons. SALM1 depletion in excitatory hippocampal primary neurons impaired Neurexin1β- and Neuroligin1-mediated excitatory synaptogenesis and reduced synaptic vesicle clustering, synaptic transmission, and synaptic vesicle release. SALM1 promoted Neurexin1β clustering in an F-actin- and PIP2-dependent manner. Two basic residues in SALM1's juxtamembrane polybasic domain are essential for this clustering. Together, these data show that SALM1 is a presynaptic organizer of synapse development by promoting F-actin/PIP2-dependent clustering of Neurexin.
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http://dx.doi.org/10.15252/embj.2018101289DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6717895PMC
September 2019

Comparative characterization of human induced pluripotent stem cells (hiPSC) derived from patients with schizophrenia and autism.

Transl Psychiatry 2019 07 29;9(1):179. Epub 2019 Jul 29.

Department Molecular Biology, NMI Natural and Medical Sciences Institute at the University of Tübingen, Markwiesenstr. 55, 72770, Reutlingen, Germany.

Human induced pluripotent stem cells (hiPSC) provide an attractive tool to study disease mechanisms of neurodevelopmental disorders such as schizophrenia. A pertinent problem is the development of hiPSC-based assays to discriminate schizophrenia (SZ) from autism spectrum disorder (ASD) models. Healthy control individuals as well as patients with SZ and ASD were examined by a panel of diagnostic tests. Subsequently, skin biopsies were taken for the generation, differentiation, and testing of hiPSC-derived neurons from all individuals. SZ and ASD neurons share a reduced capacity for cortical differentiation as shown by quantitative analysis of the synaptic marker PSD95 and neurite outgrowth. By contrast, pattern analysis of calcium signals turned out to discriminate among healthy control, schizophrenia, and autism samples. Schizophrenia neurons displayed decreased peak frequency accompanied by increased peak areas, while autism neurons showed a slight decrease in peak amplitudes. For further analysis of the schizophrenia phenotype, transcriptome analyses revealed a clear discrimination among schizophrenia, autism, and healthy controls based on differentially expressed genes. However, considerable differences were still evident among schizophrenia patients under inspection. For one individual with schizophrenia, expression analysis revealed deregulation of genes associated with the major histocompatibility complex class II (MHC class II) presentation pathway. Interestingly, antipsychotic treatment of healthy control neurons also increased MHC class II expression. In conclusion, transcriptome analysis combined with pattern analysis of calcium signals appeared as a tool to discriminate between SZ and ASD phenotypes in vitro.
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http://dx.doi.org/10.1038/s41398-019-0517-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6663940PMC
July 2019

Transcriptome and proteome profiling of neural stem cells from the human subventricular zone in Parkinson's disease.

Acta Neuropathol Commun 2019 06 3;7(1):84. Epub 2019 Jun 3.

Department of Translational Neuroscience, UMC Utrecht Brain Center, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands.

It is currently accepted that the human brain has a limited neurogenic capacity and an impaired regenerative potential. We have previously shown the existence of CD271-expressing neural stem cells (NSCs) in the subventricular zone (SVZ) of Parkinson's disease (PD) patients, which proliferate and differentiate towards neurons and glial cells in vitro. To study the molecular profile of these NSCs in detail, we performed RNA sequencing and mass spectrometry on CD271 NSCs isolated from human post-mortem SVZ and on homogenates of the SVZ. CD271 cells were isolated through magnetic cell separation (MACS). We first compared the molecular profile of CD271 NSCs to the SVZ homogenate from control donors and then compared CD271 cells to CD11b microglia. These results confirmed their neural stem cell identity. Finally we compared controls and PD patients to establish a specific molecular profile of NSCs and the SVZ in PD. While our transcriptome analysis did not identify any differentially expressed genes in the SVZ between control and PD patients, our proteome analysis revealed several proteins that were differentially expressed in PD. Some of these proteins are involved in cytoskeletal organization and mitochondrial function. Transcriptome and proteome analyses of NSCs from PD revealed changes in the expression of genes and proteins involved in metabolism, transcriptional activity and cytoskeletal organization. Our data suggest that NSCs may transit into a primed-quiescent state, that is in an "alert" non-proliferative phase in PD. Our results not only confirm pathological hallmarks of PD (e.g. impaired mitochondrial function), but also show that the NSCs from SVZ undergo significant changes at both transcriptome and proteome level following PD.
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http://dx.doi.org/10.1186/s40478-019-0736-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6545684PMC
June 2019

Combined cellomics and proteomics analysis reveals shared neuronal morphology and molecular pathway phenotypes for multiple schizophrenia risk genes.

Mol Psychiatry 2021 Mar 29;26(3):784-799. Epub 2019 May 29.

Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands.

An enigma in studies of neuropsychiatric disorders is how to translate polygenic risk into disease biology. For schizophrenia, where > 145 significant GWAS loci have been identified and only a few genes directly implicated, addressing this issue is a particular challenge. We used a combined cellomics and proteomics approach to show that polygenic risk can be disentangled by searching for shared neuronal morphology and cellular pathway phenotypes of candidate schizophrenia risk genes. We first performed an automated high-content cellular screen to characterize neuronal morphology phenotypes of 41 candidate schizophrenia risk genes. The transcription factors Tcf4 and Tbr1 and the RNA topoisomerase Top3b shared a neuronal phenotype marked by an early and progressive reduction in synapse numbers upon knockdown in mouse primary neuronal cultures. Proteomics analysis subsequently showed that these three genes converge onto the syntaxin-mediated neurotransmitter release pathway, which was previously implicated in schizophrenia, but for which genetic evidence was weak. We show that dysregulation of multiple proteins in this pathway may be due to the combined effects of schizophrenia risk genes Tcf4, Tbr1, and Top3b. Together, our data provide new biological functions for schizophrenia risk genes and support the idea that polygenic risk is the result of multiple small impacts on common neuronal signaling pathways.
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http://dx.doi.org/10.1038/s41380-019-0436-yDOI Listing
March 2021

A Fast and Economical Sample Preparation Protocol for Interaction Proteomics Analysis.

Proteomics 2019 05 18;19(9):e1900027. Epub 2019 Apr 18.

Department of Molecular and Cellular Neurobiology, Faculty of Science, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, Vrije Universiteit, Amsterdam, The Netherlands.

A simple and fast immunoprecipitation (IP) protocol is designed with the sample preparation incorporated, applicable to both low and high throughput. This new protocol combines two procedures based on magnetic beads in 96-well plate format. Protein complexes are captured by antibodies and magnetic beads conjugated with protein A. Proteins are washed and on-bead digested by using Single-Pot solid-phase sample preparation (SP3). The whole IP-SP3 approach can be completed in one day, which is considerably faster compared to the classical approach. No major quantitative differences are found between SP3 and FASP (filter-aided sample preparation) or a longer incubation protocol. Taken together, the IP-SP3 protocol is a fast and economical approach easily applicable for large-scale protein interactome analysis.
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http://dx.doi.org/10.1002/pmic.201900027DOI Listing
May 2019

Comparative Hippocampal Synaptic Proteomes of Rodents and Primates: Differences in Neuroplasticity-Related Proteins.

Front Mol Neurosci 2018 2;11:364. Epub 2018 Oct 2.

Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, Vrije Universiteit Amsterdam, Amsterdam, Netherlands.

Key to the human brain's unique capacities are a myriad of neural cell types, specialized molecular expression signatures, and complex patterns of neuronal connectivity. Neurons in the human brain communicate via well over a quadrillion synapses. Their specific contribution might be key to the dynamic activity patterns that underlie primate-specific cognitive function. Recently, functional differences were described in transmission capabilities of human and rat synapses. To test whether unique expression signatures of synaptic proteins are at the basis of this, we performed a quantitative analysis of the hippocampal synaptic proteome of four mammalian species, two primates, human and marmoset, and two rodents, rat and mouse. Abundance differences down to 1.15-fold at an FDR-corrected -value of 0.005 were reliably detected using SWATH mass spectrometry. The high measurement accuracy of SWATH allowed the detection of a large group of differentially expressed proteins between individual species and rodent vs. primate. Differentially expressed proteins between rodent and primate were found highly enriched for plasticity-related proteins.
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http://dx.doi.org/10.3389/fnmol.2018.00364DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6176546PMC
October 2018

Noelin1 Affects Lateral Mobility of Synaptic AMPA Receptors.

Cell Rep 2018 07;24(5):1218-1230

Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, VU University Amsterdam, De Boelelaan 1085, 1081 HV Amsterdam, the Netherlands. Electronic address:

Lateral diffusion on the neuronal plasma membrane of the AMPA-type glutamate receptor (AMPAR) serves an important role in synaptic plasticity. We investigated the role of the secreted glycoprotein Noelin1 (Olfactomedin-1 or Pancortin) in AMPAR lateral mobility and its dependence on the extracellular matrix (ECM). We found that Noelin1 interacts with the AMPAR with high affinity, however, without affecting rise- and decay time and desensitization properties. Noelin1 co-localizes with synaptic and extra-synaptic AMPARs and is expressed at synapses in an activity-dependent manner. Single-particle tracking shows that Noelin1 reduces lateral mobility of both synaptic and extra-synaptic GluA1-containing receptors and affects short-term plasticity. While the ECM does not constrain the synaptic pool of AMPARs and acts only extrasynaptically, Noelin1 contributes to synaptic potentiation by limiting AMPAR mobility at synaptic sites. This is the first evidence for the role of a secreted AMPAR-interacting protein on mobility of GluA1-containing receptors and synaptic plasticity.
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http://dx.doi.org/10.1016/j.celrep.2018.06.102DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6088136PMC
July 2018

Proteomics analysis identifies new markers associated with capillary cerebral amyloid angiopathy in Alzheimer's disease.

Acta Neuropathol Commun 2018 06 4;6(1):46. Epub 2018 Jun 4.

Department of Pathology, Amsterdam Neuroscience, VU University Medical Center, PO Box 7057, 1007, MB, Amsterdam, The Netherlands.

Alzheimer's disease (AD) is characterized by amyloid beta (Aβ) deposits as plaques in the parenchyma and in the walls of cortical and leptomeningeal blood vessels of the brain called cerebral amyloid angiopathy (CAA). It is suggested that CAA type-1, which refers to amyloid deposition in both capillaries and larger vessels, adds to the symptomatic manifestation of AD and correlates with disease severity. Currently, CAA cannot be diagnosed pre-mortem and disease mechanisms involved in CAA are elusive. To obtain insight in the disease mechanism of CAA and to identify marker proteins specifically associated with CAA we performed a laser dissection microscopy assisted mass spectrometry analysis of post-mortem human brain tissue of (I) AD cases with only amyloid deposits in the brain parenchyma and no vascular related amyloid, (II) AD cases with severe CAA type-1 and no or low numbers of parenchymal amyloid deposits and (III) cognitively healthy controls without amyloid deposits. By contrasting the quantitative proteomics data between the three groups, 29 potential CAA-selective proteins were identified. A selection of these proteins was analysed by immunoblotting and immunohistochemistry to confirm regulation and to determine protein localization and their relation to brain pathology. In addition, specificity of these markers in relation to other small vessel diseases including prion CAA, CADASIL, CARASAL and hypertension related small vessel disease was assessed using immunohistochemistry.Increased levels of clusterin (CLU), apolipoprotein E (APOE) and serum amyloid P-component (APCS) were observed in AD cases with CAA. In addition, we identified norrin (NDP) and collagen alpha-2(VI) (COL6A2) as highly selective markers that are clearly present in CAA yet virtually absent in relation to parenchymal amyloid plaque pathology. NDP showed the highest specificity to CAA when compared to other small vessel diseases. The specific changes in the proteome of CAA provide new insight in the pathogenesis and yields valuable selective biomarkers for the diagnosis of CAA.
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http://dx.doi.org/10.1186/s40478-018-0540-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5985582PMC
June 2018

MIR137 schizophrenia-associated locus controls synaptic function by regulating synaptogenesis, synapse maturation and synaptic transmission.

Hum Mol Genet 2018 06;27(11):1879-1891

Department of Functional Genomics, Center for Neurogenomics and Cognitive Research (CNCR), Amsterdam Neuroscience, VU University Amsterdam and VU Medical Center, 1081 HV Amsterdam, The Netherlands.

The MIR137 locus is a replicated genetic risk factor for schizophrenia. The risk-associated allele is reported to increase miR-137 expression and miR-137 overexpression alters synaptic transmission in mouse hippocampus. We investigated the cellular mechanisms underlying these observed effects in mouse hippocampal neurons in culture. First, we correlated the risk allele to expression of the genes in the MIR137 locus in human postmortem brain. Some evidence for increased MIR137HG expression was observed, especially in hippocampus of the disease-associated genotype. Second, in mouse hippocampal neurons, we confirmed previously observed changes in synaptic transmission upon miR-137 overexpression. Evoked synaptic transmission and spontaneous release were 50% reduced. We identified defects in release probability as the underlying cause. In contrast to previous observations, no evidence was obtained for selective synaptic vesicle docking defects. Instead, ultrastructural morphometry revealed multiple effects of miR-137 overexpression on docking, active zone length and total vesicle number. Moreover, proteomic analyses of neuronal protein showed that expression of Syt1 and Cplx1, previously reported as downregulated upon miR-137 overexpression, was unaltered. Immunocytochemistry of synapses overexpressing miR-137 showed normal Synaptotagmin1 and Complexin1 protein levels. Instead, our proteomic analyses revealed altered expression of genes involved in synaptogenesis. Concomitantly, synaptogenesis assays revealed 31% reduction in synapse formation. Taken together, these data show that miR-137 regulates synaptic function by regulating synaptogenesis, synaptic ultrastructure and synapse function. These effects are plausible contributors to the increased schizophrenia risk associated with miR-137 overexpression.
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http://dx.doi.org/10.1093/hmg/ddy089DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5961183PMC
June 2018

A Laser Microdissection-Liquid Chromatography-Tandem Mass Spectrometry Workflow for Post-mortem Analysis of Brain Tissue.

Methods Mol Biol 2018 ;1723:371-383

Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, VU University, Amsterdam, The Netherlands.

Improved speed and sensitivity of mass spectrometry allow the simultaneous quantification of high numbers of proteins from increasingly smaller quantities of tissue sample. Quantitative data of the proteome is highly valuable for providing unbiased information on, for example, protein expression changes related to disease or identifying related biomarkers. In brain diseases the affected area can be small and pathogenic events can be related to a specific cell type in an otherwise heterogeneous tissue type. An emerging approach dedicated to analyzing this type of samples is laser micro-dissection (LMD) combined with LC-MS/MS into a single workflow. In this chapter, we describe different options for isolating tissue suitable for LC-MS/MS analysis.
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http://dx.doi.org/10.1007/978-1-4939-7558-7_21DOI Listing
January 2019

The RNA-Binding Protein hnRNP K Mediates the Effect of BDNF on Dendritic mRNA Metabolism and Regulates Synaptic NMDA Receptors in Hippocampal Neurons.

eNeuro 2017 Nov-Dec;4(6). Epub 2017 Dec 12.

CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal.

Brain-derived neurotrophic factor (BDNF) is an important mediator of long-term synaptic potentiation (LTP) in the hippocampus. The local effects of BDNF depend on the activation of translation activity, which requires the delivery of transcripts to the synapse. In this work, we found that neuronal activity regulates the dendritic localization of the RNA-binding protein heterogeneous nuclear ribonucleoprotein K (hnRNP K) in cultured rat hippocampal neurons by stimulating BDNF-Trk signaling. Microarray experiments identified a large number of transcripts that are coimmunoprecipitated with hnRNP K, and about 60% of these transcripts are dissociated from the protein upon stimulation of rat hippocampal neurons with BDNF. studies also showed a role for TrkB signaling in the dissociation of transcripts from hnRNP K upon high-frequency stimulation (HFS) of medial perforant path-granule cell synapses of male rat dentate gyrus (DG). Furthermore, treatment of rat hippocampal synaptoneurosomes with BDNF decreased the coimmunoprecipitation of hnRNP K with mRNAs coding for glutamate receptor subunits, Ca- and calmodulin-dependent protein kinase IIβ (CaMKIIβ) and BDNF. Downregulation of hnRNP K impaired the BDNF-induced enhancement of NMDA receptor (NMDAR)-mediated mEPSC, and similar results were obtained upon inhibition of protein synthesis with cycloheximide. The results demonstrate that BDNF regulates specific populations of hnRNP-associated mRNAs in neuronal dendrites and suggests an important role of hnRNP K in BDNF-dependent forms of synaptic plasticity.
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http://dx.doi.org/10.1523/ENEURO.0268-17.2017DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5732018PMC
August 2018

Comparative Analyses of Data Independent Acquisition Mass Spectrometric Approaches: DIA, WiSIM-DIA, and Untargeted DIA.

Proteomics 2018 01;18(1)

Department of Molecular and Cellular Neurobiology, CNCR, Amsterdam Neuroscience, Vrije Universiteit, Amsterdam, The Netherlands.

Data-independent acquisition (DIA) is an emerging technology for quantitative proteomics. Current DIA focusses on the identification and quantitation of fragment ions that are generated from multiple peptides contained in the same selection window of several to tens of m/z. An alternative approach is WiSIM-DIA, which combines conventional DIA with wide-SIM (wide selected-ion monitoring) windows to partition the precursor m/z space to produce high-quality precursor ion chromatograms. However, WiSIM-DIA has been underexplored; it remains unclear if it is a viable alternative to DIA. We demonstrate that WiSIM-DIA quantified more than 24 000 unique peptides over five orders of magnitude in a single 2 h analysis of a neuronal synapse-enriched fraction, compared to 31 000 in DIA. There is a strong correlation between abundance values of peptides quantified in both the DIA and WiSIM-DIA datasets. Interestingly, the S/N ratio of these peptides is not correlated. We further show that peptide identification directly from DIA spectra identified >2000 proteins, which included unique peptides not found in spectral libraries generated by DDA.
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http://dx.doi.org/10.1002/pmic.201700304DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5817406PMC
January 2018

Correlation profiling of brain sub-cellular proteomes reveals co-assembly of synaptic proteins and subcellular distribution.

Sci Rep 2017 09 21;7(1):12107. Epub 2017 Sep 21.

Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands.

Protein correlation profiling might assist in defining co-assembled proteins and subcellular distribution. Here, we quantified the proteomes of five biochemically isolated mouse brain cellular sub-fractions, with emphasis on synaptic compartments, from three brain regions, hippocampus, cortex and cerebellum. We demonstrated the expected co-fractionation of canonical synaptic proteins belonging to the same functional groups. The enrichment profiles also suggested the presence of many novel pre- and post-synaptic proteins. Using super-resolution microscopy on primary neuronal culture we confirmed the postsynaptic localization of PLEKHA5 and ADGRA1. We further detected profound brain region specific differences in the extent of enrichment for some functionally associated proteins. This is exemplified by different AMPA receptor subunits and substantial differences in sub-fraction distribution of their potential interactors, which implicated the differences of AMPA receptor complex compositions. This resource aids the identification of proteins partners and subcellular distribution of synaptic proteins.
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http://dx.doi.org/10.1038/s41598-017-11690-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5608747PMC
September 2017

Tomosyn associates with secretory vesicles in neurons through its N- and C-terminal domains.

PLoS One 2017 26;12(7):e0180912. Epub 2017 Jul 26.

Department of Functional Genomics, Centre for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University, Amsterdam, The Netherlands.

The secretory pathway in neurons requires efficient targeting of cargos and regulatory proteins to their release sites. Tomosyn contributes to synapse function by regulating synaptic vesicle (SV) and dense-core vesicle (DCV) secretion. While there is large support for the presynaptic accumulation of tomosyn in fixed preparations, alternative subcellular locations have been suggested. Here we studied the dynamic distribution of tomosyn-1 (Stxbp5) and tomosyn-2 (Stxbp5l) in mouse hippocampal neurons and observed a mixed diffuse and punctate localization pattern of both isoforms. Tomosyn-1 accumulations were present in axons and dendrites. As expected, tomosyn-1 was expressed in about 75% of the presynaptic terminals. Interestingly, also bidirectional moving tomosyn-1 and -2 puncta were observed. Despite the lack of a membrane anchor these puncta co-migrated with synapsin and neuropeptide Y, markers for respectively SVs and DCVs. Genetic blockade of two known tomosyn interactions with synaptotagmin-1 and its cognate SNAREs did not abolish its vesicular co-migration, suggesting an interplay of protein interactions mediated by the WD40 and SNARE domains. We hypothesize that the vesicle-binding properties of tomosyns may control the delivery, pan-synaptic sharing and secretion of neuronal signaling molecules, exceeding its canonical role at the plasma membrane.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0180912PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5529015PMC
October 2017

Multi-level characterization of balanced inhibitory-excitatory cortical neuron network derived from human pluripotent stem cells.

PLoS One 2017 6;12(6):e0178533. Epub 2017 Jun 6.

Department of Pediatrics / Child Neurology, Amsterdam Neuroscience, VU University Medical Center, Amsterdam, The Netherlands.

Generation of neuronal cultures from induced pluripotent stem cells (hiPSCs) serve the studies of human brain disorders. However we lack neuronal networks with balanced excitatory-inhibitory activities, which are suitable for single cell analysis. We generated low-density networks of hPSC-derived GABAergic and glutamatergic cortical neurons. We used two different co-culture models with astrocytes. We show that these cultures have balanced excitatory-inhibitory synaptic identities using confocal microscopy, electrophysiological recordings, calcium imaging and mRNA analysis. These simple and robust protocols offer the opportunity for single-cell to multi-level analysis of patient hiPSC-derived cortical excitatory-inhibitory networks; thereby creating advanced tools to study disease mechanisms underlying neurodevelopmental disorders.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0178533PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5460818PMC
September 2017

Age-Dependent Protein Aggregation Initiates Amyloid-β Aggregation.

Front Aging Neurosci 2017 17;9:138. Epub 2017 May 17.

Protein Aggregation and Aging, German Center for Neurodegenerative DiseasesTübingen, Germany.

Aging is the most important risk factor for neurodegenerative diseases associated with pathological protein aggregation such as Alzheimer's disease. Although aging is an important player, it remains unknown which molecular changes are relevant for disease initiation. Recently, it has become apparent that widespread protein aggregation is a common feature of aging. Indeed, several studies demonstrate that 100s of proteins become highly insoluble with age, in the absence of obvious disease processes. Yet it remains unclear how these misfolded proteins aggregating with age affect neurodegenerative diseases. Importantly, several of these aggregation-prone proteins are found as minor components in disease-associated hallmark aggregates such as amyloid-β plaques or neurofibrillary tangles. This co-localization raises the possibility that age-dependent protein aggregation directly contributes to pathological aggregation. Here, we show for the first time that highly insoluble proteins from aged or aged mouse brains, but not from young individuals, can initiate amyloid-β aggregation . We tested the seeding potential at four different ages across the adult lifespan of . Significantly, protein aggregates formed during the early stages of aging did not act as seeds for amyloid-β aggregation. Instead, we found that changes in protein aggregation occurring during middle-age initiated amyloid-β aggregation. Mass spectrometry analysis revealed several late-aggregating proteins that were previously identified as minor components of amyloid-β plaques and neurofibrillary tangles such as 14-3-3, Ubiquitin-like modifier-activating enzyme 1 and Lamin A/C, highlighting these as strong candidates for cross-seeding. Overall, we demonstrate that widespread protein misfolding and aggregation with age could be critical for the initiation of pathogenesis, and thus should be targeted by therapeutic strategies to alleviate neurodegenerative diseases.
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http://dx.doi.org/10.3389/fnagi.2017.00138DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5434662PMC
May 2017

Dynamics of the mouse brain cortical synaptic proteome during postnatal brain development.

Sci Rep 2016 10 17;6:35456. Epub 2016 Oct 17.

Department of Molecular and Cellular Neurobiology, Center for Neurogenomics &Cognitive Research, Neuroscience Campus Amsterdam, VU University, Amsterdam, The Netherlands.

Development of the brain involves the formation and maturation of numerous synapses. This process requires prominent changes of the synaptic proteome and potentially involves thousands of different proteins at every synapse. To date the proteome analysis of synapse development has been studied sparsely. Here, we analyzed the cortical synaptic membrane proteome of juvenile postnatal days 9 (P9), P15, P21, P27, adolescent (P35) and different adult ages P70, P140 and P280 of C57Bl6/J mice. Using a quantitative proteomics workflow we quantified 1560 proteins of which 696 showed statistically significant differences over time. Synaptic proteins generally showed increased levels during maturation, whereas proteins involved in protein synthesis generally decreased in abundance. In several cases, proteins from a single functional molecular entity, e.g., subunits of the NMDA receptor, showed differences in their temporal regulation, which may reflect specific synaptic development features of connectivity, strength and plasticity. SNARE proteins, Snap 29/47 and Stx 7/8/12, showed higher expression in immature animals. Finally, we evaluated the function of Cxadr that showed high expression levels at P9 and a fast decline in expression during neuronal development. Knock down of the expression of Cxadr in cultured primary mouse neurons revealed a significant decrease in synapse density.
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http://dx.doi.org/10.1038/srep35456DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5066275PMC
October 2016

Group 1 metabotropic glutamate receptors 1 and 5 form a protein complex in mouse hippocampus and cortex.

Proteomics 2016 10 12;16(20):2698-2705. Epub 2016 Sep 12.

Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University, Amsterdam, the Netherlands.

The group 1 metabotropic glutamate receptors 1 and 5 (mGluR1/5) have been implicated in mechanisms of synaptic plasticity and may serve as potential therapeutic targets in autism spectrum disorders. The interactome of group 1 mGluRs has remained largely unresolved. Using a knockout-controlled interaction proteomics strategy we examined the mGluR5 protein complex in two brain regions, hippocampus and cortex, and identified mGluR1 as its major interactor in addition to the well described Homer proteins. We confirmed the presence of mGluR1/5 complex by (i) reverse immunoprecipitation using an mGluR1 antibody to pulldown mGluR5 from hippocampal tissue, (ii) coexpression in HEK293 cells followed by coimmunoprecipitation to reveal the direct interaction of mGluR1 and 5, and (iii) superresolution microscopy imaging of hippocampal primary neurons to show colocalization of the mGluR1/5 in the synapse.
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http://dx.doi.org/10.1002/pmic.201500400DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5129514PMC
October 2016

Functional characterisation of human synaptic genes expressed in the Drosophila brain.

Biol Open 2016 May 15;5(5):662-7. Epub 2016 May 15.

Brainwave-Discovery Ltd., Hugh Robson Building, 15 George Square, Edinburgh EH8 9XD, UK Institute of Adaptive and Neural Computation, School of Informatics, University of Edinburgh, Edinburgh EH8 9AB, UK

Drosophila melanogaster is an established and versatile model organism. Here we describe and make available a collection of transgenic Drosophila strains expressing human synaptic genes. The collection can be used to study and characterise human synaptic genes and their interactions and as controls for mutant studies. It was generated in a way that allows the easy addition of new strains, as well as their combination. In order to highlight the potential value of the collection for the characterisation of human synaptic genes we also use two assays, investigating any gain-of-function motor and/or cognitive phenotypes in the strains in this collection. Using these assays we show that among the strains made there are both types of gain-of-function phenotypes investigated. As an example, we focus on the three strains expressing human tyrosine protein kinase Fyn, the small GTPase Rap1a and human Arc, respectively. Of the three, the first shows a cognitive gain-of-function phenotype while the second a motor gain-of-function phenotype. By contrast, Arc, which has no Drosophila ortholog, shows no gain-of-function phenotype.
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http://dx.doi.org/10.1242/bio.016261DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4874349PMC
May 2016

Presynaptic inhibition upon CB1 or mGlu2/3 receptor activation requires ERK/MAPK phosphorylation of Munc18-1.

EMBO J 2016 06 7;35(11):1236-50. Epub 2016 Apr 7.

Department of Functional Genomics and Clinical Genetics, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, Vrije Universiteit (VU) and VU Medical Center, Amsterdam, The Netherlands

Presynaptic cannabinoid (CB1R) and metabotropic glutamate receptors (mGluR2/3) regulate synaptic strength by inhibiting secretion. Here, we reveal a presynaptic inhibitory pathway activated by extracellular signal-regulated kinase (ERK) that mediates CB1R- and mGluR2/3-induced secretion inhibition. This pathway is triggered by a variety of events, from foot shock-induced stress to intense neuronal activity, and induces phosphorylation of the presynaptic protein Munc18-1. Mimicking constitutive phosphorylation of Munc18-1 results in a drastic decrease in synaptic transmission. ERK-mediated phosphorylation of Munc18-1 ultimately leads to degradation by the ubiquitin-proteasome system. Conversely, preventing ERK-dependent Munc18-1 phosphorylation increases synaptic strength. CB1R- and mGluR2/3-induced synaptic inhibition and depolarization-induced suppression of excitation (DSE) are reduced upon ERK/MEK pathway inhibition and further reduced when ERK-dependent Munc18-1 phosphorylation is blocked. Thus, ERK-dependent Munc18-1 phosphorylation provides a major negative feedback loop to control synaptic strength upon activation of presynaptic receptors and during intense neuronal activity.
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http://dx.doi.org/10.15252/embj.201592244DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4888233PMC
June 2016

Impact of genetic variation on synaptic protein levels in genetically diverse mice.

Proteomics 2016 Apr 10;16(7):1123-30. Epub 2016 Mar 10.

Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University Amsterdam, Amsterdam, The Netherlands.

The relative abundance of synaptic proteins shapes protein complex formation and is essential for synapse function and behavioral fitness. Here, we have used a panel of highly diverse inbred strains of mice-NOD/LtJ, A/J, 129S1/SvImJ, FVB/NJ, C57BL/6J, WSB/EiJ, PWK/PhJ, and CAST/EiJ-to quantify the effects of genetic variation on the synaptic proteome between strains. Using iTRAQ-based quantitative proteome analyses, we detected significant differences in ∼20% of 400 core synaptic proteins. Surprisingly, the differentially abundant proteins showed a modest range of variation across strains, averaging about 1.3-fold. Analysis of protein abundance covariation across the eight strains identified known protein-protein relations (proteins of Arp2/3 complex), as well as novel relations (e.g. Dlg family, Fscn1). Moreover, covariation of synaptic proteins was substantially tighter (∼fourfold more dense than chance level) than corresponding networks of synaptic transcripts (∼twofold more dense than chance). The tight stoichiometry and coherent synaptic protein covariation networks suggest more intense evolutionary selection at this level of molecular organization. In conclusion, genetic diversity in the mouse genome differentially affects the transcriptome and proteome, and only partially penetrates the synaptic proteome. Protein abundance correlation analyses in genetically divergent strains can complement protein-protein interaction network analyses, to provide insight into protein interactomes.
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http://dx.doi.org/10.1002/pmic.201500154DOI Listing
April 2016

Profiling the human hippocampal proteome at all pathologic stages of Alzheimer's disease.

Alzheimers Dement 2016 06 6;12(6):654-68. Epub 2016 Jan 6.

Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University Amsterdam, Amsterdam, The Netherlands. Electronic address:

Introduction: We performed a comprehensive quantitative proteomics study on human hippocampus tissue involving all Braak stages to assess changes in protein abundance over the various stages of Alzheimer's disease (AD).

Methods: Hippocampal subareas CA1 and subiculum of 40 cases were isolated using laser capture microdissection and analyzed using mass spectrometry. Immunoblotting and immunohistochemistry were used for validation.

Results: Over the Braak stages, an altered expression was found for 372 proteins including changes in levels of extracellular matrix components, and in calcium-dependent signaling proteins. Early changes were observed in levels of proteins related to cytoskeletal dynamics and synaptic components including an increase in RIMS1 and GRIK4. Several synaptic proteins, such as BSN, LIN7A, DLG2, -3, and -4, exhibit an early-up, late-down expression pattern.

Discussion: This study provides new insight into AD-dependent changes in protein levels in the hippocampus during AD pathology, identifying potential novel therapeutic targets and biomarkers.
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http://dx.doi.org/10.1016/j.jalz.2015.11.002DOI Listing
June 2016