Publications

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104 Publications visible to you, out of a total of 104

Abstract (Expand)

Mitochondria account for essential cellular pathways, from ATP production to nucleotide metabolism, and their deficits lead to neurological disorders and contribute to the onset of age-related diseases. Direct neuronal reprogramming aims at replacing neurons lost in such conditions, but very little is known about the impact of mitochondrial dysfunction on the direct reprogramming of human cells. Here, we explore the effects of mitochondrial dysfunction on the neuronal reprogramming of induced pluripotent stem cell (iPSC)-derived astrocytes carrying mutations in the NDUFS4 gene, important for Complex I and associated with Leigh syndrome. This led to the identification of the unfolded protein response as a major hurdle in the direct neuronal conversion of not only astrocytes and fibroblasts from patients but also control human astrocytes and fibroblasts. Its transient inhibition potently improves reprogramming by influencing the mitochondria-endoplasmic-reticulum-stress-mediated pathways. Taken together, disease modeling using patient cells unraveled novel general hurdles and ways to overcome these in human astrocyte-to-neuron reprogramming.

Authors: G. Sonsalla, A. B. Malpartida, T. Riedemann, M. Gusic, E. Rusha, G. Bulli, S. Najas, A. Janjic, B. A. Hersbach, P. Smialowski, M. Drukker, W. Enard, J. H. M. Prehn, H. Prokisch, M. Gotz, G. Masserdotti

Date Published: 3rd Apr 2024

Publication Type: Journal

Abstract (Expand)

Traumatic brain injury leads to a highly orchestrated immune- and glial cell response partially responsible for long-lasting disability and the development of secondary neurodegenerative diseases. A holistic understanding of the mechanisms controlling the responses of specific cell types and their crosstalk is required to develop an efficient strategy for better regeneration. Here, we combine spatial and single-cell transcriptomics to chart the transcriptomic signature of the injured male murine cerebral cortex, and identify specific states of different glial cells contributing to this signature. Interestingly, distinct glial cells share a large fraction of injury-regulated genes, including inflammatory programs downstream of the innate immune-associated pathways Cxcr3 and Tlr1/2. Systemic manipulation of these pathways decreases the reactivity state of glial cells associated with poor regeneration. The functional relevance of the discovered shared signature of glial cells highlights the importance of our resource enabling comprehensive analysis of early events after brain injury.

Authors: Christina Koupourtidou, Veronika Schwarz, Hananeh Aliee, Simon Frerich, Judith Fischer-Sternjak, Riccardo Bocchi, Tatiana Simon-Ebert, Xianshu Bai, Swetlana Sirko, Frank Kirchhoff, Martin Dichgans, Magdalena Götz, Fabian J Theis, Jovica Ninkovic

Date Published: 3rd Apr 2024

Publication Type: Journal

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

Abstract (Expand)

Oxytocin-expressing paraventricular hypothalamic neurons (PVN<sup>OT</sup> neurons) integrate afferent signals from the gut, including cholecystokinin (CCK), to adjust whole-body energy homeostasis. However, the molecular underpinnings by which PVN<sup>OT</sup> neurons orchestrate gut-to-brain feeding control remain unclear. Here, we show that mice undergoing selective ablation of PVN<sup>OT</sup> neurons fail to reduce food intake in response to CCK and develop hyperphagic obesity on a chow diet. Notably, exposing wild-type mice to a high-fat/high-sugar (HFHS) diet recapitulates this insensitivity toward CCK, which is linked to diet-induced transcriptional and electrophysiological aberrations specifically in PVN<sup>OT</sup> neurons. Restoring OT pathways in diet-induced obese (DIO) mice via chemogenetics or polypharmacology sufficiently re-establishes CCK's anorexigenic effects. Last, by single-cell profiling, we identify a specialized PVN<sup>OT</sup> neuronal subpopulation with increased κ-opioid signaling under an HFHS diet, which restrains their CCK-evoked activation. In sum, we document a (patho)mechanism by which PVN<sup>OT</sup> signaling uncouples a gut-brain satiation pathway under obesogenic conditions.

Authors: Tim Gruber, Franziska Lechner, Cahuê Murat, Raian E Contreras, Eva Sanchez-Quant, Viktorian Miok, Konstantinos Makris, Ophélia Le Thuc, Ismael González-García, Elena García-Clave, Ferdinand Althammer, Quirin Krabichler, Lisa M DeCamp, Russell G Jones, Dominik Lutter, Rhiannan H Williams, Paul T Pfluger, Timo D Müller, Stephen C Woods, John Andrew Pospisilik, Celia P Martinez-Jimenez, Matthias H Tschöp, Valery Grinevich, Cristina Garcia-Caceres

Date Published: 31st Oct 2023

Publication Type: Journal

Abstract (Expand)

Axon degeneration and functional decline in myelin diseases are often attributed to loss of myelin but their relation is not fully understood. Perturbed myelinating glia can instigate chronic neuroinflammation and contribute to demyelination and axonal damage. Here we study mice with distinct defects in the proteolipid protein 1 gene that develop axonal damage which is driven by cytotoxic T cells targeting myelinating oligodendrocytes. We show that persistent ensheathment with perturbed myelin poses a risk for axon degeneration, neuron loss, and behavioral decline. We demonstrate that CD8(+) T cell-driven axonal damage is less likely to progress towards degeneration when axons are efficiently demyelinated by activated microglia. Mechanistically, we show that cytotoxic T cell effector molecules induce cytoskeletal alterations within myelinating glia and aberrant actomyosin constriction of axons at paranodal domains. Our study identifies detrimental axon-glia-immune interactions which promote neurodegeneration and possible therapeutic targets for disorders associated with myelin defects and neuroinflammation.

Authors: J. Groh, T. Abdelwahab, Y. Kattimani, M. Horner, S. Loserth, V. Gudi, R. Adalbert, F. Imdahl, A. E. Saliba, M. Coleman, M. Stangel, M. Simons, R. Martini

Date Published: 30th Oct 2023

Publication Type: Journal

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

Abstract (Expand)

Multiple sclerosis (MS) involves the infiltration of autoreactive T cells into the CNS, yet we lack a comprehensive understanding of the signaling pathways that regulate this process. Here, we conducted a genome-wide in vivo CRISPR screen in a rat MS model and identified 5 essential brakes and 18 essential facilitators of T cell migration to the CNS. While the transcription factor ETS1 limits entry to the CNS by controlling T cell responsiveness, three functional modules, centered around the adhesion molecule alpha4-integrin, the chemokine receptor CXCR3 and the GRK2 kinase, are required for CNS migration of autoreactive CD4(+) T cells. Single-cell analysis of T cells from individuals with MS confirmed that the expression of these essential regulators correlates with the propensity of CD4(+) T cells to reach the CNS. Our data thus reveal key regulators of the fundamental step in the induction of MS lesions.

Authors: A. Kendirli, C. de la Rosa, K. F. Lammle, K. Eglseer, I. J. Bauer, V. Kavaka, S. Winklmeier, L. Zhuo, C. Wichmann, L. A. Gerdes, T. Kumpfel, K. Dornmair, E. Beltran, M. Kerschensteiner, N. Kawakami

Date Published: 4th Oct 2023

Publication Type: Journal

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