Filter and export

Publications

What is a Publication?
34 Publications visible to you, out of a total of 34
Rational correction of pathogenic conformational defects in HTRA1.

Abstract (Expand)

Loss-of-function mutations in the homotrimeric serine protease HTRA1 cause cerebral vasculopathy. Here, we establish independent approaches to achieve the functional correction of trimer assembly … defects. Focusing on the prototypical R274Q mutation, we identify an HTRA1 variant that promotes trimer formation thus restoring enzymatic activity in vitro. Genetic experiments in Htra1<sup>R274Q</sup> mice further demonstrate that expression of this protein-based corrector in trans is sufficient to stabilize HtrA1-R274Q and restore the proteomic signature of the brain vasculature. An alternative approach employs supramolecular chemical ligands that shift the monomer-trimer equilibrium towards proteolytically active trimers. Moreover, we identify a peptidic ligand that activates HTRA1 monomers. Our findings open perspectives for tailored protein repair strategies.

Authors: Nathalie Beaufort, Linda Ingendahl, Melisa Merdanovic, Andree Schmidt, David Podlesainski, Tim Richter, Thorben Neumann, Michael Kuszner, Ingrid R Vetter, Patricia Stege, Steven G Burston, Anto Filipovic, Yasser B Ruiz-Blanco, Kenny Bravo-Rodriguez, Joel Mieres-Perez, Christine Beuck, Stephan Uebel, Monika Zobawa, Jasmin Schillinger, Rainer Malik, Katalin Todorov-Völgyi, Juliana Rey, Annabell Roberti, Birte Hagemeier, Benedikt Wefers, Stephan A Müller, Wolfgang Wurst, Elsa Sanchez-Garcia, Alexander Zimmermann, Xiao-Yu Hu, Tim Clausen, Robert Huber, Stefan F Lichtenthaler, Carsten Schmuck, Michael Giese, Markus Kaiser, Michael Ehrmann, Martin Dichgans

Date Published: 16th Jul 2024

Publication Type: Journal

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

Abstract (Expand)

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 identify BACE2 as the protease shedding the lymphangiogenic vascular endothelial growth factor receptor 3 (VEGFR3). Inactivation of BACE2, but not BACE1, inhibited shedding of VEGFR3 from primary human lymphatic endothelial cells (LECs) and reduced release of the shed, soluble VEGFR3 (sVEGFR3) ectodomain into the blood of mice, non-human primates and humans. Functionally, BACE2 inactivation increased full-length VEGFR3 and enhanced VEGFR3 signaling in LECs and also in vivo in zebrafish, where enhanced migration of LECs was observed. Thus, this study identifies BACE2 as a modulator of lymphangiogenic VEGFR3 signaling and demonstrates the utility of sVEGFR3 as a pharmacodynamic plasma marker for BACE2 activity in vivo, a prerequisite for developing BACE1-selective inhibitors for a safer prevention of Alzheimer's disease.

Authors: A. Schmidt, B. Hrupka, F. van Bebber, S. Sunil Kumar, X. Feng, S. K. Tschirner, M. Assfalg, S. A. Muller, L. S. Hilger, L. I. Hofmann, M. Pigoni, G. Jocher, I. Voytyuk, E. L. Self, M. Ito, K. Hyakkoku, A. Yoshimura, N. Horiguchi, R. Feederle, B. De Strooper, S. Schulte-Merker, E. Lammert, D. Moechars, B. Schmid, S. F. Lichtenthaler

Date Published: 18th Jun 2024

Publication Type: Journal

Cellular depletion of major cathepsin proteases reveals their concerted activities for lysosomal proteolysis.

Abstract (Expand)

Proteins delivered by endocytosis or autophagy to lysosomes are degraded by exo- and endoproteases. In humans 15 lysosomal cathepsins (CTS) act as important physiological regulators. The cysteine … proteases CTSB and CTSL and the aspartic protease CTSD are the most abundant and functional important lysosomal proteinases. Whereas their general functions in proteolysis in the lysosome, their individual substrate, cleavage specificity, and their possible sequential action on substrate proteins have been previously studied, their functional redundancy is still poorly understood. To address a possible common role of highly expressed and functional important CTS proteases, we generated CTSB-, CTSD-, CTSL-, and CTSBDL-triple deficient (KO) human neuroblastoma-derived SH-SY5Y cells and CTSB-, CTSD-, CTSL-, CTSZ and CTSBDLZ-quadruple deficient (KO) HeLa cells. These cells with a combined cathepsin deficiency exhibited enlarged lysosomes and accumulated lipofuscin-like storage material. The lack of the three (SH-SY5Y) or four (HeLa) major CTSs caused an impaired autophagic flux and reduced degradation of endocytosed albumin. Proteome analyses of parental and CTS-depleted cells revealed an enrichment of cleaved peptides, lysosome/autophagy-associated proteins, and potentially endocytosed membrane proteins like the amyloid precursor protein (APP), which can be subject to endocytic degradation. Amino- and carboxyterminal APP fragments accumulated in the multiple CTS-deficient cells, suggesting that multiple CTS-mediated cleavage events regularly process APP. In summary, our analyses support the idea that different lysosomal cathepsins act in concert, have at least partially and functionally redundant substrates, regulate protein degradation in autophagy, and control cellular proteostasis, as exemplified by their involvement in the degradation of APP fragments.

Authors: Lisa Gallwitz, Florian Bleibaum, Matthias Voss, Michaela Schweizer, Katharina Spengler, Dominic Winter, Frederic Zöphel, Stephan Müller, Stefan Lichtenthaler, Markus Damme, Paul Saftig

Date Published: 22nd May 2024

Publication Type: Journal

Proteomics of mouse brain endothelium uncovers dysregulation of vesicular transport pathways during aging.

Abstract (Expand)

Age-related decline in brain endothelial cell (BEC) function contributes critically to neurological 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-based mouse BEC enrichment protocol compatible with proteomics and resolved the profiles of protein abundance changes during aging. Unsupervised cluster analysis revealed a segregation of age-related protein dynamics with biological functions, including a downregulation of vesicle-mediated transport. We found a dysregulation of key regulators of endocytosis and receptor recycling (most prominently Arf6), macropinocytosis and lysosomal degradation. In gene deletion and overexpression experiments, Arf6 affected endocytosis pathways in endothelial cells. Our approach uncovered changes not picked up by transcriptomic studies, such as accumulation of vesicle cargo and receptor ligands, including Apoe. Proteomic analysis of BECs from Apoe-deficient mice revealed a signature of accelerated aging. Our findings provide a resource for analysing BEC function during aging.

Authors: K. Todorov-Volgyi, J. Gonzalez-Gallego, S. A. Muller, N. Beaufort, R. Malik, M. Schifferer, M. I. Todorov, D. Crusius, S. Robinson, A. Schmidt, J. Korbelin, F. Bareyre, A. Erturk, C. Haass, M. Simons, D. Paquet, S. F. Lichtenthaler, M. Dichgans

Date Published: 22nd Apr 2024

Publication Type: Journal

Deciphering sources of PET signals in the tumor microenvironment of glioblastoma at cellular resolution.

Abstract (Expand)

Various cellular sources hamper interpretation of positron emission tomography (PET) biomarkers in the tumor microenvironment (TME). We developed an approach of immunomagnetic cell sorting after in … vivo radiotracer injection (scRadiotracing) with three-dimensional (3D) histology to dissect the cellular allocation of PET signals in the TME. In mice with implanted glioblastoma, translocator protein (TSPO) radiotracer uptake per tumor cell was higher compared to tumor-associated microglia/macrophages (TAMs), validated by protein levels. Translation of in vitro scRadiotracing to patients with glioma immediately after tumor resection confirmed higher single-cell TSPO tracer uptake of tumor cells compared to immune cells. Across species, cellular radiotracer uptake explained the heterogeneity of individual TSPO-PET signals. In consideration of cellular tracer uptake and cell type abundance, tumor cells were the main contributor to TSPO enrichment in glioblastoma; however, proteomics identified potential PET targets highly specific for TAMs. Combining cellular tracer uptake measures with 3D histology facilitates precise allocation of PET signals and serves to validate emerging novel TAM-specific radioligands.

Authors: L. M. Bartos, S. V. Kirchleitner, Z. I. Kolabas, S. Quach, A. Beck, J. Lorenz, J. Blobner, S. A. Mueller, S. Ulukaya, L. Hoeher, I. Horvath, K. Wind-Mark, A. Holzgreve, V. C. Ruf, L. Gold, L. H. Kunze, S. T. Kunte, P. Beumers, H. E. Park, M. Antons, A. Zatcepin, N. Briel, L. Hoermann, R. Schaefer, D. Messerer, P. Bartenstein, M. J. Riemenschneider, S. Lindner, S. Ziegler, J. Herms, S. F. Lichtenthaler, A. Erturk, J. C. Tonn, L. von Baumgarten, N. L. Albert, M. Brendel

Date Published: 27th Oct 2023

Publication Type: Journal

Targeting the TCA cycle can ameliorate widespread axonal energy deficiency in neuroinflammatory lesions.

Abstract (Expand)

Inflammation in the central nervous system 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. We show that neuroinflammatory lesions in the mouse spinal cord cause widespread and persisting axonal ATP deficiency, which precedes mitochondrial oxidation and calcium overload. This axonal energy deficiency is associated with impaired electron transport chain function, but also an upstream imbalance of tricarboxylic acid (TCA) cycle enzymes, with several, including key rate-limiting, enzymes being depleted in neuronal mitochondria in experimental models and in MS lesions. Notably, viral overexpression of individual TCA enzymes can ameliorate the axonal energy deficits in neuroinflammatory lesions, suggesting that TCA cycle dysfunction in MS may be amendable to therapy.

Authors: Y. H. Tai, D. Engels, G. Locatelli, I. Emmanouilidis, C. Fecher, D. Theodorou, S. A. Muller, S. Licht-Mayer, M. Kreutzfeldt, I. Wagner, N. P. de Mello, S. N. Gkotzamani, L. Trovo, A. Kendirli, A. Aljovic, M. O. Breckwoldt, R. Naumann, F. M. Bareyre, F. Perocchi, D. Mahad, D. Merkler, S. F. Lichtenthaler, M. Kerschensteiner, T. Misgeld

Date Published: 25th Aug 2023

Publication Type: Journal

Reactivated endogenous retroviruses promote protein aggregate spreading.

Abstract (Expand)

Prion-like spreading of protein misfolding is a characteristic of 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 spreading of proteopathic seeds. We show that upregulation of endogenous retroviruses drastically increases the dissemination of protein aggregates between cells in culture, a process that can be inhibited by targeting the viral envelope protein or viral protein processing. Human endogenous retrovirus envelopes of four different clades also elevate intercellular spreading of proteopathic seeds, including pathological Tau. Our data support a role of endogenous retroviruses in protein misfolding diseases and suggest that antiviral drugs could represent promising candidates for inhibiting protein aggregate spreading.

Authors: S. Liu, S. E. Heumuller, A. Hossinger, S. A. Muller, O. Buravlova, S. F. Lichtenthaler, P. Denner, I. M. Vorberg

Date Published: 18th Aug 2023

Publication Type: Journal

Powered by
 (v.1.15.0)
About FAIRDOM | About SyNergy (Munich Cluster for Systems Neurology) | Funding and Programmes | Credits
Copyright © 2008 - 2024 The University of Manchester and HITS gGmbH