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19 Publications visible to you, out of a total of 19
Astrocyte heterogeneity reveals region-specific astrogenesis in the white matter.

Abstract (Expand)

Astrocyte heterogeneity has been well explored, but our understanding of white matter (WM) astrocytes and their distinctions from gray matter (GM) astrocytes remains limited. Here, we compared astrocytes … from cortical GM and WM/corpus callosum (WM/CC) using single-cell RNA sequencing and spatial transcriptomics of the murine forebrain. The comparison revealed similarities but also significant differences between WM and GM astrocytes, including cytoskeletal and metabolic hallmarks specific to WM astrocytes with molecular properties also shared with human WM astrocytes. When we compared murine astrocytes from two different WM regions, the cortex and cerebellum, we found that they exhibited distinct, region-specific molecular properties, with the cerebellum lacking, for example, a specific cluster of WM astrocytes expressing progenitor and proliferation genes. Functional experiments confirmed astrocyte proliferation in the WM/CC, but not in the cerebellar WM, suggesting that the WM/CC may be a source of continued astrogenesis.

Authors: Riccardo Bocchi, Manja Thorwirth, Tatiana Simon-Ebert, Christina Koupourtidou, Solène Clavreul, Keegan Kolf, Patrizia Della Vecchia, Sara Bottes, Sebastian Jessberger, Jiafeng Zhou, Gulzar Wani, Gregor-Alexander Pilz, Jovica Ninkovic, Annalisa Buffo, Swetlana Sirko, Magdalena Götz, Judith Fischer-Sternjak

Date Published: 24th Feb 2025

Publication Type: Journal

Single Cell Deletion of the Transcription Factors Trps1 and Sox9 in Astrocytes Reveals Novel Functions in the Adult Cerebral Cortex.

Abstract (Expand)

Astrocytes play key roles in brain function, but how these are orchestrated by transcription factors (TFs) in the adult brain and aligned with astrocyte heterogeneity is largely unknown. Here we examined … the localization and function of the novel astrocyte TF Trps1 (Transcriptional Repressor GATA Binding 1) and the well-known astrocyte TF Sox9 by Cas9-mediated deletion using Mokola-pseudotyped lentiviral delivery into the adult cerebral cortex. Trps1 and Sox9 levels showed heterogeneity among adult cortical astrocytes, which prompted us to explore the effects of deleting either Sox9 or Trps1 alone or simultaneously at the single-cell (by patch-based single-cell transcriptomics) and tissue levels (by spatial transcriptomics). This revealed TF-specific functions in astrocytes, such as synapse maintenance with the strongest effects on synapse number achieved by Trps1 deletion and a common effect on immune response. In addition, spatial transcriptomics showed non-cell-autonomous effects on the surrounding cells, such as oligodendrocytes and other immune cells with TF-specific differences on the type of immune cells: Trps1 deletion affecting monocytes specifically, while Sox9 deletion acting mostly on microglia and deletion of both TF affecting mostly B cells. Taken together, this study reveals novel roles of Trps1 and Sox9 in adult astrocytes and their communication with other glial and immune cells.

Authors: Poornemaa Natarajan, Christina Koupourtidou, Thibault de Resseguier, Manja Thorwirth, Riccardo Bocchi, Judith Fischer-Sternjak, Sarah Gleiss, Diana Rodrigues, Michael H Myoga, Jovica Ninkovic, Giacomo Masserdotti, Magdalena Götz

Date Published: 28th Nov 2024

Publication Type: Journal

Direct neuronal reprogramming of mouse astrocytes is associated with multiscale epigenome remodeling and requires Yy1.

Abstract (Expand)

Direct neuronal reprogramming is a promising approach to regenerate neurons from local glial cells. However, mechanisms of epigenome remodeling and co-factors facilitating this process are unclear. In … this study, we combined single-cell multiomics with genome-wide profiling of three-dimensional nuclear architecture and DNA methylation in mouse astrocyte-to-neuron reprogramming mediated by Neurogenin2 (Ngn2) and its phosphorylation-resistant form (PmutNgn2), respectively. We show that Ngn2 drives multilayered chromatin remodeling at dynamic enhancer-gene interaction sites. PmutNgn2 leads to higher reprogramming efficiency and enhances epigenetic remodeling associated with neuronal maturation. However, the differences in binding sites or downstream gene activation cannot fully explain this effect. Instead, we identified Yy1, a transcriptional co-factor recruited by direct interaction with Ngn2 to its target sites. Upon deletion of Yy1, activation of neuronal enhancers, genes and ultimately reprogramming are impaired without affecting Ngn2 binding. Thus, our work highlights the key role of interactors of proneural factors in direct neuronal reprogramming.

Authors: Allwyn Pereira, Jeisimhan Diwakar, Giacomo Masserdotti, Sude Beşkardeş, Tatiana Simon, Younju So, Lucía Martín-Loarte, Franziska Bergemann, Lakshmy Vasan, Tamas Schauer, Anna Danese, Riccardo Bocchi, Maria Colomé-Tatché, Carol Schuurmans, Anna Philpott, Tobias Straub, Boyan Bonev, Magdalena Götz

Date Published: 2nd Jul 2024

Publication Type: Journal

Direct neuronal reprogramming of NDUFS4 patient cells identifies the unfolded protein response as a novel general reprogramming hurdle.

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

Shared inflammatory glial cell signature after stab wound injury, revealed by spatial, temporal, and cell-type-specific profiling of the murine cerebral cortex.

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

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

Met/HGFR triggers detrimental reactive microglia in TBI.

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

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