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57 Publications visible to you, out of a total of 57
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

Multiomic ALS signatures highlight subclusters and sex differences suggesting the MAPK pathway as therapeutic target.

Abstract (Expand)

Amyotrophic lateral sclerosis (ALS) is a debilitating motor neuron disease and lacks effective disease-modifying treatments. This study utilizes a comprehensive multiomic approach to investigate the … early and sex-specific molecular mechanisms underlying ALS. By analyzing the prefrontal cortex of 51 patients with sporadic ALS and 50 control subjects, alongside four transgenic mouse models (C9orf72-, SOD1-, TDP-43-, and FUS-ALS), we have uncovered significant molecular alterations associated with the disease. Here, we show that males exhibit more pronounced changes in molecular pathways compared to females. Our integrated analysis of transcriptomes, (phospho)proteomes, and miRNAomes also identified distinct ALS subclusters in humans, characterized by variations in immune response, extracellular matrix composition, mitochondrial function, and RNA processing. The molecular signatures of human subclusters were reflected in specific mouse models. Our study highlighted the mitogen-activated protein kinase (MAPK) pathway as an early disease mechanism. We further demonstrate that trametinib, a MAPK inhibitor, has potential therapeutic benefits in vitro and in vivo, particularly in females, suggesting a direction for developing targeted ALS treatments.

Authors: Lucas Caldi Gomes, Sonja Hänzelmann, Fabian Hausmann, Robin Khatri, Sergio Oller, Mojan Parvaz, Laura Tzeplaeff, Laura Pasetto, Marie Gebelin, Melanie Ebbing, Constantin Holzapfel, Stefano Fabrizio Columbro, Serena Scozzari, Johanna Knöferle, Isabell Cordts, Antonia F Demleitner, Marcus Deschauer, Claudia Dufke, Marc Sturm, Qihui Zhou, Pavol Zelina, Emma Sudria-Lopez, Tobias B Haack, Sebastian Streb, Magdalena Kuzma-Kozakiewicz, Dieter Edbauer, R Jeroen Pasterkamp, Endre Laczko, Hubert Rehrauer, Ralph Schlapbach, Christine Carapito, Valentina Bonetto, Stefan Bonn, Paul Lingor

Date Published: 1st 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

A TBK1 variant causes autophagolysosomal and motoneuron pathology without neuroinflammation in mice.

Abstract (Expand)

Heterozygous mutations in the TBK1 gene can cause amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). The majority of TBK1-ALS/FTD patients carry deleterious loss-of-expression … mutations, and it is still unclear which TBK1 function leads to neurodegeneration. We investigated the impact of the pathogenic TBK1 missense variant p.E696K, which does not abolish protein expression, but leads to a selective loss of TBK1 binding to the autophagy adaptor protein and TBK1 substrate optineurin. Using organelle-specific proteomics, we found that in a knock-in mouse model and human iPSC-derived motor neurons, the p.E696K mutation causes presymptomatic onset of autophagolysosomal dysfunction in neurons precipitating the accumulation of damaged lysosomes. This is followed by a progressive, age-dependent motor neuron disease. Contrary to the phenotype of mice with full Tbk1 knock-out, RIPK/TNF-alpha-dependent hepatic, neuronal necroptosis, and overt autoinflammation were not detected. Our in vivo results indicate autophagolysosomal dysfunction as a trigger for neurodegeneration and a promising therapeutic target in TBK1-ALS/FTD.

Authors: D. Brenner, K. Sieverding, J. Srinidhi, S. Zellner, C. Secker, R. Yilmaz, J. Dyckow, S. Amr, A. Ponomarenko, E. Tunaboylu, Y. Douahem, J. S. Schlag, L. Rodriguez Martinez, G. Kislinger, C. Niemann, K. Nalbach, W. P. Ruf, J. Uhl, J. Hollenbeck, L. Schirmer, A. Catanese, C. S. Lobsiger, K. M. Danzer, D. Yilmazer-Hanke, C. Munch, P. Koch, A. Freischmidt, M. Fetting, C. Behrends, R. Parlato, J. H. Weishaupt

Date Published: 6th 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

Lysosomal damage sensing and lysophagy initiation by SPG20-ITCH.

Abstract (Expand)

Cells respond to lysosomal membrane permeabilization by membrane repair or selective macroautophagy of damaged lysosomes, termed lysophagy, but it is not fully understood how this decision is made. … Here, we uncover a pathway in human cells that detects lipid bilayer perturbations in the limiting membrane of compromised lysosomes, which fail to be repaired, and then initiates ubiquitin-triggered lysophagy. We find that SPG20 binds the repair factor IST1 on damaged lysosomes and, importantly, integrates that with the detection of damage-associated lipid-packing defects of the lysosomal membrane. Detection occurs via sensory amphipathic helices in SPG20 before rupture of the membrane. If lipid-packing defects are extensive, such as during lipid peroxidation, SPG20 recruits and activates ITCH, which marks the damaged lysosome with lysine-63-linked ubiquitin chains to initiate lysophagy and thus triages the lysosome for destruction. With SPG20 being linked to neurodegeneration, these findings highlight the relevance of a coordinated lysosomal damage response for cellular homeostasis.

Authors: Pinki Gahlot, Bojana Kravic, Giulia Rota, Johannes van den Boom, Sophie Levantovsky, Nina Schulze, Elena Maspero, Simona Polo, Christian Behrends, Hemmo Meyer

Date Published: 18th Apr 2024

Publication Type: Journal

Injury-specific factors in the cerebrospinal fluid regulate astrocyte plasticity in the human brain.

Abstract (Expand)

The glial environment influences neurological disease progression, yet much of our knowledge still relies on preclinical animal studies, especially regarding astrocyte heterogeneity. In murine models … of traumatic brain injury, beneficial functions of proliferating reactive astrocytes on disease outcome have been unraveled, but little is known regarding if and when they are present in human brain pathology. Here we examined a broad spectrum of pathologies with and without intracerebral hemorrhage and found a striking correlation between lesions involving blood-brain barrier rupture and astrocyte proliferation that was further corroborated in an assay probing for neural stem cell potential. Most importantly, proteomic analysis unraveled a crucial signaling pathway regulating this astrocyte plasticity with GALECTIN3 as a novel marker for proliferating astrocytes and the GALECTIN3-binding protein LGALS3BP as a functional hub mediating astrocyte proliferation and neurosphere formation. Taken together, this work identifies a therapeutically relevant astrocyte response and their molecular regulators in different pathologies affecting the human cerebral cortex.

Authors: Swetlana Sirko, Christian Schichor, Patrizia Della Vecchia, Fabian Metzger, Giovanna Sonsalla, Tatiana Simon, Martina Bürkle, Sofia Kalpazidou, Jovica Ninkovic, Giacomo Masserdotti, Jean-Frederic Sauniere, Valentina Iacobelli, Stefano Iacobelli, Claire Delbridge, Stefanie M Hauck, Jörg-Christian Tonn, Magdalena Götz

Date Published: 8th Dec 2023

Publication Type: Journal

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