Publications

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

Abstract (Expand)

The complexity of signaling events and cellular responses unfolding in neuronal, glial, and immune cells upon traumatic brain injury (TBI) constitutes an obstacle in elucidating pathophysiological links and targets for intervention. We use array phosphoproteomics in a murine mild blunt TBI to reconstruct the temporal dynamics of tyrosine-kinase signaling in TBI and then scrutinize the large-scale effects of perturbation of Met/HGFR, VEGFR1, and Btk signaling by small molecules. We show Met/HGFR as a selective modifier of early microglial response and that Met/HGFR blockade prevents the induction of microglial inflammatory mediators, of reactive microglia morphology, and TBI-associated responses in neurons and vasculature. Both acute and prolonged Met/HGFR inhibition ameliorate neuronal survival and motor recovery. Early elevation of HGF itself in the cerebrospinal fluid of TBI patients suggests that this mechanism has translational value in human subjects. Our findings identify Met/HGFR as a modulator of early neuroinflammation in TBI with promising translational potential.

Authors: Rida Rehman, Michael Miller, Sruthi Sankari Krishnamurthy, Jacob Kjell, Lobna Elsayed, Stefanie M Hauck, Florian Olde Heuvel, Alison Conquest, Akila Chandrasekar, Albert Ludolph, Tobias Boeckers, Medhanie A Mulaw, Maria Cristina Morganti-Kossmann, Aya Takeoka, Francesco Roselli, Magdalena Götz

Date Published: 27th Dec 2022

Publication Type: Journal

Abstract (Expand)

Amyloid-beta (Abeta) deposition is an initiating factor in Alzheimer's disease (AD). Microglia are the brain immune cells that surround and phagocytose Abeta plaques, but their phagocytic capacity declines in AD. This is in agreement with studies that associate AD risk loci with genes regulating the phagocytic function of immune cells. Immunotherapies are currently pursued as strategies against AD and there are increased efforts to understand the role of the immune system in ameliorating AD pathology. Here, we evaluated the effect of the Abeta targeting ACI-24 vaccine in reducing AD pathology in an amyloidosis mouse model. ACI-24 vaccination elicited a robust and sustained antibody response in APPPS1 mice with an accompanying reduction of Abeta plaque load, Abeta plaque-associated ApoE and dystrophic neurites as compared to non-vaccinated controls. Furthermore, an increased number of NLRP3-positive plaque-associated microglia was observed following ACI-24 vaccination. In contrast to this local microglial activation at Abeta plaques, we observed a more ramified morphology of Abeta plaque-distant microglia compared to non-vaccinated controls. Accordingly, bulk transcriptomic analysis revealed a trend towards the reduced expression of several disease-associated microglia (DAM) signatures that is in line with the reduced Abeta plaque load triggered by ACI-24 vaccination. Our study demonstrates that administration of the Abeta targeting vaccine ACI-24 reduces AD pathology, suggesting its use as a safe and cost-effective AD therapeutic intervention.

Authors: J. Rudan Njavro, M. Vukicevic, E. Fiorini, L. Dinkel, S. A. Muller, A. Berghofer, C. Bordier, S. Kozlov, A. Halle, K. Buschmann, A. Capell, C. Giudici, M. Willem, R. Feederle, S. F. Lichtenthaler, C. Babolin, P. Montanari, A. Pfeifer, M. Kosco-Vilbois, S. Tahirovic

Date Published: 24th Dec 2022

Publication Type: Journal

Abstract (Expand)

Spatial molecular profiling of complex tissues is essential to investigate cellular function in physiological and pathological states. However, methods for molecular analysis of large biological specimens imaged in 3D are lacking. Here, we present DISCO-MS, a technology that combines whole-organ/whole-organism clearing and imaging, deep-learning-based image analysis, robotic tissue extraction, and ultra-high-sensitivity mass spectrometry. DISCO-MS yielded proteome data indistinguishable from uncleared samples in both rodent and human tissues. We used DISCO-MS to investigate microglia activation along axonal tracts after brain injury and characterized early- and late-stage individual amyloid-beta plaques in a mouse model of Alzheimer's disease. DISCO-bot robotic sample extraction enabled us to study the regional heterogeneity of immune cells in intact mouse bodies and aortic plaques in a complete human heart. DISCO-MS enables unbiased proteome analysis of preclinical and clinical tissues after unbiased imaging of entire specimens in 3D, identifying diagnostic and therapeutic opportunities for complex diseases. VIDEO ABSTRACT.

Authors: H. S. Bhatia, A. D. Brunner, F. Ozturk, S. Kapoor, Z. Rong, H. Mai, M. Thielert, M. Ali, R. Al-Maskari, J. C. Paetzold, F. Kofler, M. I. Todorov, M. Molbay, Z. I. Kolabas, M. Negwer, L. Hoeher, H. Steinke, A. Dima, B. Gupta, D. Kaltenecker, O. S. Caliskan, D. Brandt, N. Krahmer, S. Muller, S. F. Lichtenthaler, F. Hellal, I. Bechmann, B. Menze, F. Theis, M. Mann, A. Erturk

Date Published: 22nd Dec 2022

Publication Type: Journal

Abstract (Expand)

Autophagy is responsible for clearance of an extensive portfolio of cargoes, which are sequestered into vesicles, called autophagosomes, and are delivered to lysosomes for degradation. The pathway is highly dynamic and responsive to several stress conditions. However, the phospholipid composition and protein contents of human autophagosomes under changing autophagy rates are elusive so far. Here, we introduce an antibody-based FACS-mediated approach for the isolation of native autophagic vesicles and ensured the quality of the preparations. Employing quantitative lipidomics, we analyze phospholipids present within human autophagic vesicles purified upon basal autophagy, starvation, and proteasome inhibition. Importantly, besides phosphoglycerides, we identify sphingomyelin within autophagic vesicles and show that the phospholipid composition is unaffected by the different conditions. Employing quantitative proteomics, we obtain cargo profiles of autophagic vesicles isolated upon the different treatment paradigms. Interestingly, starvation shows only subtle effects, while proteasome inhibition results in the enhanced presence of ubiquitin-proteasome pathway factors within autophagic vesicles. Thus, here we present a powerful method for the isolation of native autophagic vesicles, which enabled profound phospholipid and cargo analyses.

Authors: D. Schmitt, S. Bozkurt, P. Henning-Domres, H. Huesmann, S. Eimer, L. Bindila, C. Behrends, E. Boyle, F. Wilfling, G. Tascher, C. Munch, C. Behl, A. Kern

Date Published: 6th Dec 2022

Publication Type: Journal

Abstract (Expand)

Brain Abeta deposition is a key early event in the pathogenesis of Alzheimer s disease (AD), but the long presymptomatic phase and poor correlation between Abeta deposition and clinical symptoms remain puzzling. To elucidate the dependency of downstream pathologies on Abeta, we analyzed the trajectories of cerebral Abeta accumulation, Abeta seeding activity, and neurofilament light chain (NfL) in the CSF (a biomarker of neurodegeneration) in Abeta-precursor protein transgenic mice. We find that Abeta deposition increases linearly until it reaches an apparent plateau at a late age, while Abeta seeding activity increases more rapidly and reaches a plateau earlier, coinciding with the onset of a robust increase of CSF NfL. Short-term inhibition of Abeta generation in amyloid-laden mice reduced Abeta deposition and associated glial changes, but failed to reduce Abeta seeding activity, and CSF NfL continued to increase although at a slower pace. When short-term or long-term inhibition of Abeta generation was started at pre-amyloid stages, CSF NfL did not increase despite some Abeta deposition, microglial activation, and robust brain Abeta seeding activity. A dissociation of Abeta load and CSF NfL trajectories was also found in familial AD, consistent with the view that Abeta aggregation is not kinetically coupled to neurotoxicity. Rather, neurodegeneration starts when Abeta seeding activity is saturated and before Abeta deposition reaches critical (half-maximal) levels, a phenomenon reminiscent of the two pathogenic phases in prion disease.

Authors: C. Rother, R. E. Uhlmann, S. A. Muller, J. Schelle, A. Skodras, U. Obermuller, L. M. Hasler, M. Lambert, F. Baumann, Y. Xu, C. Bergmann, G. Salvadori, M. Loos, I. Brzak, D. Shimshek, U. Neumann, L. C. Walker, S. A. Schultz, J. P. Chhatwal, S. A. Kaeser, S. F. Lichtenthaler, M. Staufenbiel, M. Jucker

Date Published: 28th Nov 2022

Publication Type: Journal

Abstract

Not specified

Authors: Yaw Asare, Margarita Shnipova, Luka Živković, Christina Schlegl, Federica Tosato, Arailym Aronova, Markus Brandhofer, Laura Strohm, Nathalie Beaufort, Rainer Malik, Christian Weber, Jürgen Bernhagen, Martin Dichgans

Date Published: 19th Oct 2022

Publication Type: Journal

Abstract (Expand)

The founding member of the F-box protein family, Cyclin-F, serves as a substrate adaptor for the E3 ligase Skp1-Cul1-F-box (SCF)<sup>Cyclin-F</sup> which is responsible for ubiquitination of proteins involved in cell cycle progression, DNA damage and mitotic fidelity. Missense mutations in <i>CCNF</i> encoding for Cyclin-F are associated with amyotrophic lateral sclerosis (ALS). However, it remains elusive whether <i>CCNF</i> mutations affect the substrate adaptor function of Cyclin-F and whether altered SCF<sup>Cyclin-F</sup>-mediated ubiquitination contributes to pathogenesis in <i>CCNF</i> mutation carriers. To address these questions, we set out to identify new SCF<sup>Cyclin-F</sup> targets in neuronal and ALS patient-derived cells. Mass spectrometry-based ubiquitinome profiling of <i>CCNF</i> knockout and mutant cell lines as well as Cyclin-F proximity and interaction proteomics converged on the HSP90 chaperone machinery as new substrate candidate. Biochemical analyses provided evidence for a Cyclin-F-dependent association and ubiquitination of HSP90AB1 and implied a regulatory role that could affect the binding of a number of HSP90 clients and co-factors. Together, our results point to a possible Cyclin-F loss-of-function-mediated chaperone dysregulation that might be relevant for ALS.

Authors: A. Siebert, V. Gattringer, J. H. Weishaupt, C. Behrends

Date Published: 16th Sep 2022

Publication Type: Journal

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