Fatih DemirAarhus University | AU · Department of Biomedicine
Fatih Demir
Dr. rer. nat.
Investigating proteolysis in human plasma and the link to disease severity for inflammatory diseases
About
67
Publications
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1,091
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Introduction
Additional affiliations
September 2020 - August 2021
Position
- PostDoc Position
Description
- Investigations of proteolysis in chronic kidney disease
August 2015 - August 2020
February 2014 - January 2015
Education
February 2007 - December 2010
September 2001 - December 2006
Publications
Publications (67)
Citation: Jeong, S.; Schütz, V.; Demir, F.; Preusche, M.; Huesgen, P.; Bigler, L.; Kovacic, F.; Gutbrod, K.; Dörmann, P.; Schulz, M. Abstract: The continuous release of glucosinolates into the soil by Brassicaceae root exudation is a prerequisite to maintaining toxic levels of breakdown products such as isothiocyanates (ITCs). ITCs influence plant...
Biobanking of tissue from clinically obtained kidney biopsies for later use with multi-omic and imaging techniques is an inevitable step to overcome the need of disease model systems and towards translational medicine. Hence, collection protocols ensuring integration into daily clinical routines using preservation media not requiring liquid nitroge...
The oxidation status of N-terminal cysteines directly dictates protein stability via arginylation and proteasomal degradation. However, only a handful of proteins have been shown to be regulated via this pathway. To date, no methods to detect N-terminal cysteine reactivity and abundance has been reported. Here, we demonstrate, for the first time, t...
Secreted immune proteases Rcr3 (Required for Cladosporium resistance-3) and Pip1 (Phytophthora- inhibited protease-1) of tomato (Solanum lycopersicum) are both inhibited by Avr2 from the fungal plant pathogen Cladosporium fulvum. However, only Rcr3 acts as a decoy co-receptor that detects Avr2 in the presence of the Cf-2 immune receptor. Here, we i...
Background:
Minimal change disease and primary focal segmental glomerulosclerosis in adults, along with idiopathic nephrotic syndrome in children, are immune-mediated podocytopathies that lead to nephrotic syndrome. Autoantibodies targeting nephrin have been found in patients with minimal change disease, but their clinical and pathophysiological r...
Lysine is an essential amino acid that serves as a building block for proteins and plays a role in metabolic processes. While a recent study provided evidence that lysine is beneficial for hypertension-associated kidney disease, possibly through inhibiting renal tubular reabsorption and forming new lysine conjugates, knowledge about the role of lys...
The mutual exchange of extracellular vesicles across kingdom borders is a feature of many plant-microbe interactions. The occurrence and cargos of extracellular vesicles has been studied in several instances, but their dynamics in the course of infection have remained elusive. Here we used two different procedures, differential high-speed centrifug...
Secreted immune proteases Rcr3 and Pip1 of tomato are both inhibited by Avr2 from the fungal plant pathogen Cladosporium fulvum but only Rcr3 act as a decoy co-receptor that detects Avr2 in the presence of the Cf-2 immune receptor. Here, we identified crucial Rcr3 residues for Cf-2-mediated signalling and bioengineered various proteases to trigger...
BACKGROUND
SGLT2 (sodium-glucose cotransporter 2) inhibitors (SGLT2i) can protect the kidneys and heart, but the underlying mechanism remains poorly understood.
METHODS
To gain insights on primary effects of SGLT2i that are not confounded by pathophysiologic processes or are secondary to improvement by SGLT2i, we performed an in-depth proteomics,...
Plant legumains are crucial for processing seed storage proteins and are critical regulators of plant programmed cell death. Although research on legumains boosted recently, little is known about their activity regulation. In our study, we used pull-down experiments to identify AtCYT6 as a natural inhibitor of legumain isoform β (AtLEGβ) in Arabido...
Kidney organoids are a promising model to study kidney disease, but their use is constrained by limited knowledge of their functional protein expression profile. Here, we define the organoid proteome and transcriptome trajectories over culture duration and upon exposure to TNFα, a cytokine stressor. Older organoids increase deposition of extracellu...
Increasing drought phenomena pose a serious threat to agricultural productivity. Although plants have multiple ways to respond to the complexity of drought stress, the underlying mechanisms of stress sensing and signaling remain unclear. The role of the vasculature, in particular the phloem, in facilitating inter‐organ communication is critical and...
Plant legumains are crucial for processing seed storage proteins and are critical regulators of plant programmed cell death. Although research on legumains boosted recently, little is known about their activity regulation. In our study, we used pull-down experiments to identify AtCYT6 as a natural inhibitor of legumain isoform β (AtLEGβ) in Arabido...
The lipid kinase VPS34 orchestrates autophagy, endocytosis, and metabolism and is implicated in cancer and metabolic disease. The proximal tubule in the kidney is a key metabolic organ that controls reabsorption of nutrients such as fatty acids, amino acids, sugars, and proteins. Here, by combining metabolomics, proteomics, and phosphoproteomics an...
Increasing drought phenomena pose a serious threat to agricultural productivity. Although plants have multiple ways to respond to the complexity of drought stress, the underlying mechanisms of stress sensing and signalling remain unclear. The role of the vasculature, in particular the phloem, in facilitating inter-organ communication is critical. H...
Kidney organoids are a promising model to study kidney disease, but use is constrained by limited knowledge of their functional protein expression profile. We aimed to define the organoid proteome and transcriptome trajectories over culture duration and upon exposure to TNFα, a cytokine stressor. Older organoids increased deposition of extracellula...
Hypertension and kidney disease have been repeatedly associated with genomic variants and alterations of lysine metabolism. Here, we combined stable isotope labeling with untargeted metabolomics to investigate lysine’s metabolic fate in vivo. Dietary 13C6 labeled lysine was tracked to lysine metabolites across various organs. Globally, lysine react...
The podocyte is a key cell in maintaining renal filtration barrier integrity. Several recent studies have analyzed the entity of genome-coded molecules in the podocyte at deep resolution. This avenue of "podocyte-ome" research was enabled by a variety of techniques, including single-cell transcriptomics, FACS-sorting with and without genetically en...
BACKGROUND AND AIMS
Kidney organoids are a valuable and innovative model to understand genetic diseases, kidney development and transcriptomic dynamics. However, their proteome has not been analyzed so far. It is unclear how their proteome changes during differentiation, and if more complex disease processes such as inflammatory tissue responses co...
Protein N-termini provide unique and distinguishing information on proteolytically processed or N-terminally modified proteoforms. Also splicing, use of alternative translation initiation sites, and a variety of co- and post-translational N-terminal modifications generate distinct proteoforms that are unambiguously identified by their N-termini. Ho...
Substrate sequence specificity is a fundamental characteristic of proteolytic enzymes. Hundreds of proteases are encoded in plant genomes, but the vast majority of them have not been characterized and their distinct specificity remains largely unknown. Here we present our current protocol for profiling sequence specificity of plant proteases using...
A large variety of enrichment procedures for protein N-termini have been developed to trace protease activity and determine precise cleavage sites, as well as other N-terminal protein modifications. Typically, enriched N-terminal peptides are identified by tandem mass spectrometry using standard database search engines, in many cases the popular Ma...
Protein modification by enzymatic breaking and forming of peptide bonds significantly expands the repertoire of genetically encoded protein sequences. The dual protease-ligase legumain exerts the two opposing activities within a single protein scaffold. Primarily localized to the endolysosomal system, legumain represents a key enzyme in the generat...
Proteases play a central role in regulating renal pathophysiology and are increasingly evaluated as actionable drug targets. Here, we review the role of proteolytic systems in inflammatory kidney disease. Inflammatory kidney diseases are associated with broad dysregulations of extracellular and intracellular proteolysis. As an example of a proteoly...
Background: The glomerulus comprises podocytes, mesangial, and endothelial cells, which jointly determine glomerular filtration. Understanding this intricate functional unit beyond the transcriptome requires bulk isolation of these cell-types for biochemical investigations. We developed a globally applicable t ripartite i solation method for m urin...
Site-specific proteolytic processing is an important, irreversible post-translational protein modification with implications in many diseases. Enrichment of protein N-terminal peptides followed by mass spectrometry-based identification and quantification enables proteome-wide characterization of proteolytic processes and protease substrates but is...
Plants secrete various defence-related proteins into the apoplast, including proteases. Papain-like cysteine proteases (PLCPs) are central components of the plant immune system. To overcome plant immunity and successfully colonise their hosts, several plant pathogens secrete effector proteins inhibiting plant PLCPs. We hypothesized that not only pa...
The ATP-dependent metalloprotease FtsH12 (filamentation temperature sensitive protein H 12) has been suggested to participate in a heteromeric motor complex, driving protein translocation into the chloroplast. FtsH12 was immuno-detected in proplastids, seedlings, leaves, and roots. Expression of Myc-tagged FtsH12 under its native promotor allowed i...
Plants secrete various defence-related proteins into the apoplast, including proteases. Papain-like cysteine proteases (PLCPs) are central components of the plant immune system. To overcome plant immunity and successfully colonise their hosts, several plant pathogens secrete effector proteins inhibiting plant PLCPs. We hypothesized that not only pa...
The vacuolar cysteine protease legumain plays important functions in seed maturation and plant programmed cell death. Because of their dual protease and ligase activity, plant legumains have become of particular biotechnological interest e.g. for the synthesis of cyclic peptides for drug design or for protein engineering. However, the molecular mec...
The mammalian mitochondrial proteome consists of more than 1100 annotated proteins and their proteostasis is regulated by only a few ATP-dependent protease complexes. Technical advances in protein mass spectrometry allowed for detailed description of the mitoproteome from different species and tissues and their changes under specific conditions. Ho...
Bottom-up mass spectrometry-based proteomics utilizes proteolytic enzymes with well character-ized specificities to generate peptides amenable for identification by high throughput tandem mass spectrometry. Trypsin, which cuts specifically after the basic residues lysine and arginine, is the predominant enzyme used for proteome digestion, although...
Protein N termini unambiguously identify truncated, alternatively translated or modified proteoforms with distinct functions and reveal perturbations in disease. Selective enrichment of N-terminal peptides is necessary to achieve proteome-wide coverage for unbiased identification of site-specific regulatory proteolytic processing and protease subst...
Ustilago maydis is a biotrophic fungus causing corn smut disease in maize. The secreted effector protein Pit2 is an inhibitor of papain-like cysteine proteases (PLCPs) essential for virulence. Pit2 inhibitory function relies on a conserved 14 amino acids motif (PID14). Here we show that synthetic PID14 peptides act more efficiently as PLCP inhibito...
Protein N-termini reveal fundamental regulatory mechanisms and their perturbation in disease. Current terminome identification approaches are limited to whole organs or expandable cultured cells. We present a robust, sensitive, scalable and automatable method for system-wide identification of thousands of N-termini from minute samples. Identificati...
Site-specific proteolytic processing is an irreversible post-translational protein modification with essential regulatory functions. Dedicated methods enable proteome-wide characterization of differentially processed proteoforms based on their distinct protease-generated N termini. Exemplary profiling of murine glomeruli revealed processed forms of...
Background
Vitamin K (VK)‐dependent proteases are major players in blood coagulation including the initiation as well as the regulation of the cascade. Five different members of this protease family have been described comprising the coagulation factors VII (FVII), IX (FIX), X (FX), protein C (PC) and prothrombin (FII). FVII, FIX, FX and PC share a...
Acute kidney injury (AKI) leads to significant morbidity and mortality; unfortunately, strategies to prevent or treat AKI are lacking. In recent years, several preconditioning protocols have been shown to be effective in inducing organ protection in rodent models. Here, we characterized two of these interventions—caloric restriction and hypoxic pre...
Mass developments of toxin-producing cyanobacteria are frequently observed in freshwater ecosystems due to eutrophication and global warming. These mass developments can partly be attributed to cyanobacterial toxins, such as protease inhibitors (PIs), which inhibit digestive serine proteases of Daphnia, the major herbivore of phytoplankton and cyan...
AMPA receptors are essential for fast excitatory transmission in the CNS. Autoantibodies to AMPA receptors have been identified in humans with autoimmune encephalitis and severe defects of hippocampal function. Here, combining electrophysiology and high-resolution imaging with neuronal culture preparations and passive-transfer models in wild-type a...
Table S1. Clinical, magnetic resonance imaging, and electroencephalography findings in patients with anti‐NMDAR encephalitis.
Table S2. Routine CSF and PB analysis and antibody titers of patients with anti‐NMDAR encephalitis.
Table S3. Neuropsychological domains with respective tests applied during neuropsychological testing of patients with anti...
Objective
Autoimmune encephalitis is most frequently associated with anti‐NMDAR autoantibodies. Their pathogenic relevance has been suggested by passive transfer of patients' cerebrospinal fluid (CSF) in mice in vivo. We aimed to analyze the intrathecal plasma cell repertoire, identify autoantibody‐producing clones, and characterize their antibody...
Regulated intracellular proteostasis, controlled in part by proteolysis, is essential in maintaining the integrity of podocytes and the glomerular filtration barrier of the kidney. We applied a novel proteomics technology that enables proteome-wide identification, mapping, and quantification of protein N-termini to comprehensively characterize clea...
Autoimmune encephalitis (AIE) syndromes comprise a recently identified group of inflammatory CNS disorders characterized by symptoms of limbic and extra-limbic dysfunction. Typically, AIE syndromes are associated with distinct autoantibody signatures specific for neuronal cell surface or synaptic protein antigens. One of the more frequent AIE syndr...
I. II. III. IV. V. VI. VII. References SUMMARY: Proteolysis is a central regulatory mechanism of protein homeostasis and protein function that affects all aspects of plant life. Higher plants encode for hundreds of proteases, but their physiological substrates and hence their molecular functions remain mostly unknown. Current quantitative mass spec...
Protein N termini are a unique window to the functional state of the proteome, revealing translation initiation sites, co-translation truncation and modification, posttranslational maturation, and further proteolytic processing into different proteoforms with distinct functions. As a direct readout of proteolytic activity, protein N termini further...
Aims In the central nervous system, NMDA receptors play a pivotal role, however, their role in pancreatic islets has been largely unexplored or is controversial. We hypothesized that NMDA receptors are involved in glucose stimulated insulin secretion from beta cells and might serve as novel drug targets for diabetes treatment. Methods We generated...
The phytohormone abscisic acid (ABA) plays a key role in the plant response to drought stress. Hence, ABA-dependent gene transcription and ion transport is regulated by a variety of protein kinases and phosphatases. However, the nature of the membrane-delimited ABA signal transduction steps remains largely unknown. To gain insight into plasma membr...
Background
Sterols and Sphingolipids form lipid clusters in the plasma membranes of cell types throughout the animal and plant kingdoms. These lipid domains provide a medium for protein signaling complexes at the plasma membrane and are also observed to be principal regions of membrane contact at the inception of infection. We visualized different...
Figure S1. FM4-64/BD-SM staining of protoplasts. FM4-64/BD-SM staining on protoplasts, 20 h post cell wall removal. Polarization was even more enhanced after this time period (A-H). (A; E) FM4-64 fluorescence. (B; F) BD-SM fluorescence. In the merged images clear-cut polarizations were detected (C; G, arrows). Tranmission images (D; H).
Figure S2. Example for correlation analyses. For statistically relevant correlation analyses two ROI’s within the plasma membranes of protoplasts were chosen and the Pearson and Spearman correlation coefficients calculated from confocal images (see methods section). The images selected are of (A) an unpolarized protoplast from Figure
5, C and two 1...
Arabidopsis thaliana (A.th.) mesophyll cells play a pivotal role in the regulation of the drought stress response. The signaling & transport components involved in drought stress regulation within lipid rafts of the plasma membrane were investigated by DRM isolation from highly purified plasma membranes. Detergent treatment with Brij-98 and Triton...
Questions
Question (1)
It is (1+) and strongly present with high ACN content at the end of our LC gradients (Setup: Ultimate 3000RSLCnano HPLC coupled to an impactII MS running plant proteomics samples). Didn't find any information about such a mass - it is also present in blanks and we have already exchanged solvents to highest purity (Merck hypergrade ACN) which improves situation but the signal seems to return.
