Proteomics

Endothelial Aging

No description specified

Proteomics of inflammasome activation for rapid immune responses

No description specified

The Alzheimer's disease-linked protease BACE2 cleaves VEGFR3 and modulates its signaling

The beta-secretase BACE1 is a central drug target for Alzheimer’s disease. Clinically tested, BACE1-directed inhibitors also block the homologous protease BACE2. Yet, little is known about physiological BACE2 substrates and functions in vivo. Here, we performed glycoprotein enrichment and subsequent discovery proteomics to identify substrates of the protease BACE2 in plasma of mice. Therefore, we analysed plasma from BACE2 KO, BACE1/2 double KO and WT controls, as well as BACE1 KO with a separate
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Proteomics of mouse brain endothelium uncovers dysregulation of vesicular transport pathways during aging

Age-related decline in brain endothelial cell (BEC) function critically contributes to cerebrovascular and neurodegenerative disease. Comprehensive atlases of the BEC transcriptome have become available but results from proteomic profiling are lacking. To gain insights into endothelial pathways affected by aging, we developed a magnetic-activated cell sorting (MACS)-based mouse BEC enrichment protocol compatible with high-resolution mass-spectrometry and analysed the profiles of protein abundance
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Deciphering sources of PET signals in the tumor microenvironment of glioblastoma at cellular resolution

The 18 kDa translocator protein (TSPO) emerges as an important PET biomarker to assess the tumor microenvironment (TME) in glioblastoma. However, various cellular sources hamper interpretation and biological understanding of TSPO and other immune biomarkers in the TME. Thus, we established a novel method, combining immunomagnetic cell sorting after radiotracer injection (scRadiotracing) with 3D histology via light sheet microscopy and proteomics to dissect cellular allocation of TSPO enrichment
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Reactivated endogenous retroviruses promote protein aggregate spreading

Prion-like spreading of protein misfolding is characteristic for neurodegenerative diseases, but the exact mechanisms of intercellular protein aggregate dissemination remain unresolved. Evidence accumulates that endogenous retroviruses, remnants of viral germline infections that are normally epigenetically silenced, become upregulated in neurodegenerative diseases such as amyotrophic lateral sclerosis and tauopathies. Here we uncover that activation of endogenous retroviruses affects prion-like
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Targeting the TCA cycle can ameliorate widespread axonal energy deficiency in neuroinflammatory lesions

Inflammation in the central nervous system (CNS) can impair the function of neuronal mitochondria and contributes to axon degeneration in the common neuroinflammatory disease multiple sclerosis (MS). Here we combine cell type-specific mitochondrial proteomics with in vivo biosensor imaging to dissect how inflammation alters the molecular composition and functional capacity of neuronal mitochondria. Neuroinflammatory lesions in the mouse spinal cord cause widespread and persisting axonal ATP
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The Alzheimer's disease-linked protease BACE1 modulates neuronal IL-6 signaling through shedding of the receptor gp130

The protease BACE1 is a major drug target for Alzheimer’s disease, but chronic BACE1 inhibition is associated with non-progressive worsening that may be caused by modulation of unknown physiological BACE1 substrates. To identify in vivo-relevant BACE1 substrates we applied pharmacoproteomics to non-human-primate cerebrospinal fluid (CSF) after acute treatment with BACE inhibitors. Besides SEZ6, the strongest, dose-dependent reduction was observed for the pro-inflammatory cytokine receptor
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Spatial proteomics reveals secretory pathway disturbances caused by neuropathy-associated TECPR2

Hereditary sensory and autonomic neuropathy 9 (HSAN9) is a rare neurological disease caused by mutations in the gene encoding for Tectonin β-propeller repeat containing protein 2 (TECPR2) which possibly result in loss of the protein. Beside its potential role in autophagy, TECPR2 may serve as positive modulator of COPII-mediated ER export. However, the molecular consequences of TECPR2 deficiency for the secretory pathway remain unclear, in particular with regard to specific cargo proteins. By
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Beneficial Effect of ACI-24 Vaccination on Aβ Plaque Pathology and Microglial Phenotypes in an Amyloidosis Mouse Model

No description specified

Spatial proteomics in three-dimensional intact specimens

Spatial molecular profiling of complex tissues is essential to investigate cellular function in physiological and pathological states. However, methods for molecular analysis of biological specimens imaged in 3D as a whole are lacking. Here, we present DISCO-MS, a technology combining whole-organ/ism imaging, deep learning-based image analysis, robotic tissue extraction and ultra-high sensitivity mass spectrometry. DISCO-MS yielded qualitative and quantitative proteomics data indistinguishable
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Experimental evidence for temporal uncoupling of brain Aβ deposition and neurodegenerative sequelae

The earliest defining event in the pathogenesis of Alzheimer´s disease (AD) is the intracerebral deposition of Abeta, which starts at least 20 years before the onset of dementia. The link between Abeta and downstream neurodegeneration leading to dementia remains unclear, a critical gap in knowledge at a time when clinical trials are increasingly shifting to pre-symptomatic disease stages. Consequently, the design of preventive treatment strategies based on biomarkers remains an important challenge.
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Signatures of glial activity can be detected in the CSF proteome

Here, we took advantage of well-defined mouse models for β-amyloidosis (APPPS1) to explore proteome changes in the cerebrospinal fluid which are related to these distinct proteopathic lesions. Non-targeted liquid chromatography-mass spectrometry revealed that the majority of proteins that undergo age- and disease-related changes in either mouse model was linked to microglia, and more specifically to previously described disease state-specific microglia transcriptomic signatures. The finding that
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Proteomic profiling in cerebral amyloid angiopathy reveals an overlap with CADASIL highlighting accumulation of HTRA1 and its substrates

Cerebral amyloid angiopathy (CAA) is an age-related condition and a major cause of intracerebral hemorrhage and cognitive decline that shows close links with Alzheimer's disease (AD). CAA is characterized by the aggregation of amyloid-β (Aβ) peptides and formation of Aβ deposits in the brain vasculature resulting in a disruption of the angioarchitecture. Capillaries are a critical site of Aβ pathology in CAA type 1 and become dysfunctional during disease progression. Here, applying an advanced
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Proteomic and lipidomic profiling of demyelinating lesions identifies fatty acids as modulators in lesion recovery

After demyelinating injury of the central nervous system, resolution of the mounting acute innate inflammation is crucial for the initiation of a regenerative response. To identify factors in lesion recovery after demyelination injury, we used a toxin-induced model, in which a single dose of lysolecithin is injected into the corpus callosum to induce a focal demyelinating lesion. Afterwards, we investigated the proteome of demyelinating lesions at different time points post injection (dpi) in a
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The pseudoprotease iRhom1 controls ectodomain shedding of membrane proteins in the nervous system

Description

Proteolytic ectodomain shedding of membrane proteins is a fundamental mechanism to control the communication between cells and their environment. A key protease for membrane protein shedding is ADAM17, which requires a non-proteolytic subunit, either inactive Rhomboid 1 (iRhom1) or iRhom2 for its activity. While iRhom1 and iRhom2 are coexpressed in most tissues and appear to have largely redundant functions, the brain is an organ with predominant expression of iRhom1. Yet, little is
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ADAM10-Mediated Ectodomain Shedding Is an Essential Driver of Podocyte Damage

Protoemics of endothelia, podocytes, mesangial cells from mouse

Loss of NPC1 enhances phagocytic uptake and impairs lipid trafficking in microglia

Niemann-Pick type C (NPC) disease is a rare neurodegenerative disorder mainly caused by autosomal recessive mutations in Npc1 which result in abnormal late endosomal/lysosomal lipid storage. Although microgliosis is one of the prominent pathological features, consequences of NPC1 loss on microglial function and disease outcome remain largely unknown. Here, we provide an in-depth characterization of microglial proteomic signatures and phenotypes in an NPC1-deficient (Npc1-/-) murine model. We
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An optimized quantitative proteomics method establishes the cell type-resolved mouse brain secretome

To understand how cells communicate with each other, it is essential to define the cellular secretome, a collection of proteins including soluble secreted, unconventionally secreted and proteolytically-shed proteins. Quantitative methodologies to decipher the secretome are challenging, due to the requirement of large cell numbers and abundant serum proteins that interfere with the detection of low-abundant cellular secretome proteins. Here, we miniaturized secretome analysis by developing the
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Neuronal differentiation of LUHMES cells is accompanied by substantial changes of the proteome

o study mechanisms of neurodegenerative diseases, neuronal cell lines are important model systems and are often differentiated into postmitotic neuron-like cells to resemble more closely primary neurons obtained from brains. One such cell line is the Lund Human Mesencephalic (LUHMES) cell line which can be differentiated into dopamine-like neurons and is frequently used to study mechanisms of Parkinson’s disease (PD) and neurotoxicity. Neuronal differentiation of LUHMES cells is commonly verified
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Basic Fibroblast Growth Factor 2-Induced Proteome Changes Endorse Lewy Body Pathology in Hippocampal Neurons

Lewy body (LB) pathology and loss of dopaminergic neurons are imprints of Parkinson’s disease (PD). LBs are mainly comprised of alpha-Synuclein (Dijkstra et al., 2014). Strolling detection of LBs in brain regions contribute to progressive construct of PD pathology to which molecular mechanisms are not clear (H. Braak & Del Tredici, 2017). Two key facets of LB formation are protein aggregation via misfolding and transmission of misfoldled proteins to various brain regions, eventually causing
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Fibrillar Aβ triggers microglial proteome alterations and dysfunction in Alzheimer mouse models

Microglial dysfunction is a key pathological feature of Alzheimer´s disease (AD), but little is known about proteome-wide changes in microglia during the course of AD pathogenesis and their consequences for microglial function. Here, we performed an in-depth proteomic characterization of microglia in two AD mouse models, the overexpression APPPS1 and the knock-in AppNL-G-F (APP-KI) model. Proteome changes were followed from pre-deposition to early, middle and advanced stages of amyloid plaque
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The tetraspanin Tspan15 is an essential subunit of an ADAM10 scissor complex

A disintegrin and metalloprotease 10 (ADAM10) is essential for embryonic development and impacts on diseases such as cancer, Alzheimer’s and inflammatory diseases. ADAM10 is a ‘molecular scissor’ that proteolytically cleaves the extracellular region from over 100 substrates, including Notch, amyloid precursor protein, cadherins, growth factors and chemokines. ADAM10 was recently proposed to function as six distinct scissors with different substrates, depending on its association with one of six
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Pro-inflammatory activation following demyelination is required for myelin clearance and oligodendrogenesis

Remyelination can occur naturally in demyelinating lesions, but often fails in human demyelinating diseases such as multiple sclerosis (MS). The function of the innate immune system is essential for the regenerative response, but how exactly microglia and macrophages clear myelin debris after injury and tailor a specific regenerative response is unclear. Here, we asked whether pro-inflammatory microglial/macrophage activation is required for this process. We established a novel toxin-based spinal
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Cell-type-specific profiling of brain mitochondria reveals functional and molecular diversity

Mitochondria vary in morphology and function in different tissues, however little is known about their molecular diversity among cell types. To investigate mitochondrial diversity in vivo, we developed an efficient protocol to isolate cell type-specific mitochondria based on a new MitoTag mouse. We profiled the mitochondrial proteome of three major neural cell types in cerebellum and identified a substantial number of differential mitochondrial markers for these cell types in mice and humans.
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NrCAM is a marker for substrate-selective activation of ADAM10 in Alzheimer's disease

No description specified

Signal peptide peptidase-like 2c impairs vesicular transport and cleaves SNARE proteins

Signal peptide peptidase-like 2c (SPPL2c) is the only member of the GxGD type intramembrane-cleaving aspartyl proteases that so far has not been assigned any substrates and thus its capability of proteolysis and its physiological function remain enigmatic. Based on a surprisingly high expression of SPPL2c in elongated spermatids we applied proteomics on a cellular model system with ectopic expression of SPPL2c and identified a variety of candidate substrates. The majority of these candidate
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The intramembrane protease SPPL2c promotes male germ cell development by cleaving phospholamban

Signal peptide peptidase (SPP) and the four homologous SPP-like (SPPL) proteases constitute a family of intramembrane aspartyl proteases with selectivity for type II-oriented transmembrane segments. Here, we have analysed the physiological function of the orphan protease SPPL2c, previously considered to represent a non-expressed pseudogene. We identified proteolytic activity of SPPL2c towards selected tail-anchored proteins. Despite shared ER localization, SPPL2c and SPP exhibit distinct, though
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TBK1/ALS

While deleterious mutations are responsible for the vast majority of TBK1-linked ALS/FTD cases, the ALS/FTD causing missense mutation p.E696K leads to a selective loss of TBK1/optineurin binding. Knock-in of this specific missense mutation causes progressive autophagolysosomal dysfunction and an ALS/FTD-like phenotype in mice, while, as opposed to TBK1 deletion, RIPK/TNF-α-dependent necroptosis or overt inflammation are absent. Our results highlight the role of autophagolysosomal dysfunction as
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COP9 signalosome/Ischemic stroke

In the context of studying the role of the COP9 signalosome (CSN) in neuroinflammation and ischemic neuronal damage, we studied the effect of the cullin NEDDylation state-modifying drugs MLN4924 and CSN5i-3 in BV2 microglial cells, an immortalized murine cell line featuring many of the characteristics of primary microglia. Owing to its potent inhibitory effect on the NEDDylation cascade, MLN4924 exhibits a CSN5-like anti-inflammatory activity. Csn5i-3 is a small molecule inhibitor that specifically
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TECPR2/secretory pathway

Hereditary sensory and autonomic neuropathy 9 (HSAN9) is a rare neurological disease caused by mutations in the gene encoding for Tectonin β-propeller repeat containing protein 2 (TECPR2) which possibly result in loss of the protein. Beside its potential role in autophagy, TECPR2 may serve as positive modulator of COPII-mediated ER export. However, the molecular consequences of TECPR2 deficiency for the secretory pathway remain unclear, in particular with regard to specific cargo proteins. By
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C9orf72/UBR5/Quality control

C9orf72 binds SMCR8 to from a robust complex that regulates small GTPases, lysosomal integrity and autophagy. In contrast to this functional understanding, we know far less about assembly and turnover of the C9orf72-SMCR8 complex. Loss of either subunit causes the concurrent ablation of the respective partner. However, the molecular mechanism underlying this interdependence remains elusive.

Autophagy cargo/CD4+ T cell proliferation

CD4+ T cells orchestrate both humoral and cytotoxic immune responses. While it is known that CD4+ T cell proliferation relies on autophagy, direct identification of the autophagosomal cargo involved is still missing. Here, we created a transgenic mouse model, which, for the first time, enables us to directly map the proteinaceous content of autophagosomes in any primary cell by LC3 proximity labelling. IL-7Rα, a cytokine receptor mostly found in naïve and memory T cells, was reproducibly detected
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UBQLN2/ALS

In the project “Phosphoproteomic analysis of UBQLN2 mutant cells” by Laura Strohm, Zehan Hu, Jörn Dengjel, and Christian Behrends eight sets of SILAC experiments were performed, two times four biological replicates, comparing proteome and phosphoproteome of control and UBQLN2 mutant, patient-derived lymphoblasts (LCLs).

CCNF/ALS

The founding member of the F-box protein family, Cyclin F, serves as substrate adaptor for the Ubiquitin E3 ligase Skp1-Cul1-F-box (SCF)Cyclin F which is responsible for ubiquitination of proteins involved in cell cycle progression, DNA damage and mitotic fidelity. Missense mutations in CCNF encoding for Cyclin F are associated with amyotrophic lateral sclerosis (ALS). However, it remains elusive whether CCNF mutations affect the substrate adaptor function of Cyclin F and whether altered SCFCyclin
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CNN2/Lysosome damage

To identify ubiquitylation targets following lysosomal damage in HeLa cells treated with LLOMe we performed quantitative ubiquitin-remmnant (diGly) profilig coupled to mass spectrometry (MS). In addition, we performed APEX2-based proximity biotinylation followed by MS analysis to identify proximity partners of one of the ubiquitylation targets (CNN2).

Protein content of autophagic vesicles

Autophagy is responsible for degradation of an extensive portfolio of cytosolic cargoes that are engulfed in autophagosomes to facilitate their transport to lysosomes. Besides basal autophagy, which constantly degrades cellular material, the pathway is dynamically altered by different conditions, resulting in enhanced autophagosome formation and cargo turnover. The extensive profile of autophagosome content as well as the phospholipid composition of human autophagosome membranes remains elusive.
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Proteolysis enhanced proximity proteomics

The ascorbate peroxidase APEX2 is commonly used to study the neighborhood of a protein of interest by proximity-dependent biotinylation. Here, we describe a protocol for sample processing compatible with immunoblotting and mass spectrometry that is suitable to specifically map the content of autophagosomes and potentially other transient vesicles without the need of subcellular fractionation. By combining live-cell biotinylation with proteinase K digestion of cell homogenates, proteins enriched
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Autophagosome content profiling

Identification of autophagy substrates by directing APEX2 to autophagosomes and immune isolation of lysosomes.

AMPK/Lysosomal Damage/Galectins

Proximity proteomics of GAL9 upon lysosomal damage by LLOMe or GPN. Proximity labeling was performed in SILAC labelled HEK293T cells stably expressing APEX2-GAL9.

ACSL3/GABARAPL2 interactor

We selected GABARAPL2endoHA cells for a proof-of-principle immunoprecipitation (IP) followed by mass spectrometric (MS) analysis to identify new binding partner candidates of a hATG8 family member at endogenous levels. To distinguish between candidates that bind preferentially to PE-conjugated versus unconjugated GABARAPL2 we treated stable isotope labeling with amino acids in cell culture (SILAC)-labeled GABARAPL2endoHA cells with Torin1 and BafA1 (light) or ATG7 inhibitor (heavy).

UBE2QL1/Lysosome damage

SILAC-based proximity proteomics of UAPEX2-tagged UBE2QL1 in differential LLOMe-treated HeLa cells

BAG3-mediated autophagy

HEK293T cells stably expressing N-terminally HA-tagged BAG3 were employed to screen for novel BAG3 interacting proteins.

Lysosomal targeting of TAPL

The human lysosomal polypeptide ABC transporter TAPL (ABC subfamily B member 9, ABCB9) transports 6–59 amino-acids-long polypeptides from the cytosol into lysosomes. The subcellular localization of TAPL depends solely on its N-terminal transmembrane domain TMD0, which lacks conventional targeting sequences. However, the intracellular route and the molecular mechanisms that control TAPL localization remain unclear. Here, we delineated the route of TAPL to lysosomes and investigated the determinants
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NDP52 interactome

Macroautophagy can regulate cell signalling and tumorigenesis via elusive molecular mechanisms. We establish a RAS mutant cancer cell model where the autophagy gene ATG5 is dispensable in A549 cells in vitro, yet promotes tumorigenesis in mice. ATG5 represses transcriptional activation by the TGFβ-SMAD gene regulatory pathway. However, autophagy does not terminate cytosolic signal transduction by TGFβ. Instead, we use proteomics to identify selective degradation of the signalling scaffold TRAF3.
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