Biology subjects

Schumacher, M.

Publications and source records attributed to Schumacher, M..

10 recordsLinked to original sources

bioRxiv2025

Borna disease virus 1 infection causing fatal meningoencephalomyelitis in wild European hedgehogs in known endemic areas, Germany, 2022 to 2024

Herein, we report Borna disease virus 1 (BoDV-1) infection in seven wild European hedgehogs (Erinaceus europaeus) from an endemic area in Germany. BoDV-1 causes encephalitis with a fatality rate of more than 90% in domestic mammals and humans. Currently, the bicolored white-toothed shrew (Crocidura leucodon) is the only known reservoir host. As hedgehogs are distant relatives of shrews and often cared for by humans, the cases raise concern regarding a potential zoonotic risk. All of the hedgehogs that tested positive for BoDV-1 had succumbed to neurological disease and exhibited severe polio-predominant lymphoplasmohistiocytic meningoencephalitis. However, due to the detection of viral antigens in non-neural cells in one animal, it cannot be completely excluded that some infected hedgehogs shed the virus. Although direct BoDV-1 transmission is known to be inefficient, our results emphasize the necessity of hygiene measures when handling hedgehogs, especially those with neurological signs from BoDV-1-endemic regions.

pathology↗

bioRxiv2024

Quantitative imaging of species-specific lipid transport in mammalian cells

Eukaryotic cells produce over 1000 different lipid species which tune organelle membrane properties, control signalling and store energy1,2. How lipid species are selectively sorted between organelles to maintain specific membrane identities is largely unknown due to the difficulty to image lipid transport in cells3. Here, we measured transport and metabolism of individual lipid species in mammalian cells using time-resolved fluorescence imaging of bifunctional lipid probes in combination with ultra-high resolution mass spectrometry and mathematical modelling. Quantification of lipid flux between organelles revealed that directional, non-vesicular lipid transport is responsible for fast, species-selective lipid sorting compared to slow, unspecific vesicular membrane trafficking. Using genetic perturbations, we found that coupling between active lipid flipping and passive non-vesicular transport is a mechanism for directional lipid transport. Comparison of metabolic conversion and transport rates showed that non-vesicular transport dominates the organelle distribution of lipids while species-specific phospholipid metabolism controls neutral lipid accumulation. Our results provide the first quantitative map of retrograde lipid flux in cells4. We anticipate that our pipeline for quantitative mapping of lipid flux through physical and chemical space in cells will boost our understanding of lipids in cell biology and disease.

cell biology↗

bioRxiv2024

Epigenomic landscape of the human dorsal root ganglion: sex differences and transcriptional regulation of nociceptive genes

Gene expression is influenced by chromatin architecture via controlled access of regulatory factors to DNA. To better understand gene regulation in the human dorsal root ganglion (hDRG) we used bulk and spatial transposase-accessible chromatin technology followed by sequencing (ATAC-seq). Using bulk ATAC-seq, we detected that in females diverse differentially accessible chromatin regions (DARs) mapped to the X chromosome and in males to autosomal genes. EGR1/3 and SP1/4 transcription factor binding motifs were abundant within DARs in females, and JUN, FOS and other AP-1 factors in males. To dissect the open chromatin profile in hDRG neurons, we used spatial ATAC-seq. The neuron cluster showed higher chromatin accessibility in GABAergic, glutamatergic, and interferon-related genes in females, and in Ca2+-signaling-related genes in males. Sex differences in transcription factor binding sites in neuron-proximal barcodes were consistent with the trends observed in bulk ATAC-seq data. We validated that EGR1 expression is biased to female hDRG compared to male. Strikingly, XIST, the long-noncoding RNA responsible for X inactivation, hybridization signal was found to be highly dispersed in the female neuronal but not non-neuronal nuclei suggesting weak X inactivation in female hDRG neurons. Our findings point to baseline epigenomic sex differences in the hDRG that likely underlie divergent transcriptional responses that determine mechanistic sex differences in pain.

neuroscience↗

bioRxiv2024

Replication efficiencies of human cytomegalovirus-infected epithelial cells are dependent on source of virus production

Human cytomegalovirus (HCMV) is a prevalent betaherpesvirus, and infection can lead to a range of symptomatology from mononucleosis to sepsis in immunocompromised individuals. HCMV is also the leading viral cause of congenital birth defects. Lytic replication is supported by many cell types with different kinetics and efficiencies leading to a plethora of pathologies. The goal of these studies was to elucidate HCMV replication efficiencies for viruses produced on different cell types upon infection of epithelial cells by combining experimental approaches with data-driven computational modeling. HCMV was generated from a common genetic background of TB40-BAC4, propagated on fibroblasts (TB40Fb) or epithelial cells (TB40Epi), and used to infect epithelial cells. We quantified cell-associated viral genomes (vDNA), protein levels (pUL44, pp28), and cell-free titers over time for each virus at different multiplicities of infection. We combined experimental quantification with data-driven simulations and determined that parameters describing vDNA synthesis were similar between sources. We found that pUL44 accumulation was higher in TB40Fb than TB40Epi. In contrast, pp28 accumulation was higher in TB40Epi which coincided with a significant increase in titer for TB40Epi over TB40Fb. These differences were most evident during live-cell imaging, which revealed syncytia-like formation during infection by TB40Epi. Simulations of the late lytic replication cycle yielded a larger synthesis constant for pp28 in TB40Epi along with increase in virus output despite similar rates of genome synthesis. By combining experimental and computational modeling approaches, our studies demonstrate that the cellular source of propagated virus impacts viral replication efficiency in target cell types. IMPORTANCEHuman cytomegalovirus (HCMV) is a ubiquitous pathogen that can cause serious disease under conditions of immunodeficiency and upon congenital infection. HCMV replicates in diverse cell types throughout the human body with tropism influenced by the source of the virus. Here, we investigated the contribution of viral sources to the kinetics of HCMV replication in epithelial cells using both experimental and mechanistic computational modeling approaches. These studies reveal that HCMV produced from epithelial cells exhibits a higher efficiency of replication despite similar viral DNA synthesis kinetics between viral sources. These differences likely involve a propensity of epithelial-derived virus to induce syncytia versus fibroblast-derived virus, and an accompanying higher synthesis rate of a late virion protein ultimately resulting in production of more extracellular infectious virus.

microbiology↗

bioRxiv2023

Hormonal steroids bind the Neisseria gonorrhoeae multidrug resistance regulator, MtrR, to induce a multidrug binding efflux pump and stress-response sigma factor

Overexpression of the multidrug efflux pump MtrCDE, a critical factor of multidrug-resistance in Neisseria gonorrhoeae, the causative agent of gonorrheae, is repressed by the transcriptional regulator, MtrR (multiple transferable resistance repressor). Here, we report the results from a series of in vitro experiments to identify innate, human inducers of MtrR and to understand the biochemical and structural mechanisms of the gene regulatory function of MtrR. Isothermal titration calorimetry experiments reveal that MtrR binds the hormonal steroids progesterone, {beta}-estradiol, and testosterone, all of which are present at significant concentrations at urogenital infection sites as well as ethinyl estrogen, a component of some birth control pills. Binding of these steroids results in decreased affinity of MtrR for cognate DNA, as demonstrated by fluorescence polarization-based assays. The crystal structures of MtrR bound to each steroid provided insight into the flexibility of the binding pocket, elucidated specific residue-ligand interactions, and revealed the conformational consequences of the induction mechanism of MtrR. Three residues, D171, W136 and R176 are key to the specific binding of these gonadal steroids. These studies provide a molecular understanding of the transcriptional regulation by MtrR that promotes N. gonorrhoeae survival in its human host.

biochemistry↗

bioRxiv2023

Human Cytomegalovirus Induces Significant Structural and Functional Changes in Terminally Differentiated Human Cortical Neurons

Human cytomegalovirus (HCMV) is a highly prevalent viral pathogen that typically presents asymptomatically in healthy individuals despite lifelong latency. However, in 10-15% of congenital cases, this beta-herpesvirus demonstrates direct effects on the central nervous system, including microcephaly, cognitive/learning delays, and hearing deficits. HCMV has been widely shown to infect neural progenitor cells, but the permissiveness of fully differentiated neurons to HCMV is controversial and chronically understudied, despite potential associations between HCMV infection with neurodegenerative conditions. Using a model system representative of the human forebrain, we demonstrate that induced pluripotent stem cell (iPSC)-derived, excitatory glutamatergic and inhibitory GABAergic neurons are fully permissive to HCMV, demonstrating complete viral replication, competent virion production, and spread within the culture. Interestingly, while cell proliferation was not induced in these post-mitotic neurons, HCMV did increase expression of proliferative markers Ki67 and PCNA suggesting alterations in cell cycle machinery. These finding are consistent with previous HCMV-mediated changes in various cell types and implicate the virus ability to alter proliferative pathways to promote virion production. HCMV also induces significant structural changes in forebrain neurons, such as the formation of syncytia and retraction of neurites. Finally, we demonstrate that HCMV disrupts calcium signaling and decreases neurotransmission, with action potential generation effectively silenced after 15 days post infection. Taken together, our data highlight the potential for forebrain neurons to be permissive to HCMV infection in the CNS, which could have significant implications on overall brain health and function.

neuroscience↗

bioRxiv2023

Neutralizing Antibodies with Neurotropic Factor Treatment Maintain Neurodevelopmental Gene Expression Upon Exposure to Human Cytomegalovirus

Human cytomegalovirus (HCMV) is a beta herpesvirus that causes severe congenital birth defects including microcephaly, vision loss, and hearing loss. Infection of cerebral organoids with HCMV causes significant downregulation of genes involved in critical neurodevelopmental pathways. The precise features of the infection causing this dysregulation remain unknown. Entry of HCMV into human cells is determined by the composition of glycoproteins in viral particles, which is influenced by the source of the virus. This includes a trimer complex and a pentamer complex with the latter enriched from replication in epithelial cells. To begin dissecting which features contribute to neuronal pathogenesis, we evaluated infection using virus from different sources along with the distribution of cellular entry receptors on cells in cerebral organoids. We observed significant increases in the number of viral genomes, viral spread and penetrance, and multinucleated syncytia in neural tissues infected with HCMV propagated in epithelial cells compared to fibroblasts. To determine if this was related to entry receptor distribution, we measured expressions of cellular entry receptors and observed similar distributions of all receptors on cells obtained from organoids indicating that source of virus is likely the key determinant. Next, we asked whether we could limit pathogenesis using neutralization antibodies. We found that pre-treatment with antibodies against viral glycoprotein B (gB) and gH successfully decreased viral genome levels, viral gene expression, and virus-induced syncytia. In contrast, targeting specific cellular entry receptors failed to limit infection. Using an antibody against gB, we also observed partial protection of developmental gene expression that was further improved by the addition of brain derived neurotropic factor (BDNF). These studies indicate that source of HCMV is a key determinant of neuronal pathogenesis that can be limited by neutralization antibodies and neurotropic factors.

neuroscience↗

bioRxiv2023

Chronic administration of XBD173 ameliorates cognitive deficits and neuropathology via 18 kDa translocator protein (TSPO) in a mouse model of Alzheimer disease

Alzheimers disease (AD) is characterized by the accumulation of {beta}-amyloid peptide (A{beta}). There is increasing evidence that depression may precede AD and may be an early manifestation of dementia, suggesting common mechanisms underlying both diseases. Ligands targeting the mitochondrial translocator protein (18 kDa) (TSPO), promote neurosteroidogenesis and may be neuroprotective. Moreover, TSPO is upregulated in AD. To study whether the TSPO ligand XBD173 may exert early neuroprotective effects in AD pathology we investigated the impact of XBD173 on amyloid toxicity and neuroplasticity in mouse models. We show that XBD173 (emapunil), via neurosteroid-mediated signaling via delta subunit-containing GABAA receptors, prevents the neurotoxic effect of A{beta} on long-term potentiation (CA1-LTP) in the hippocampus and prevents the loss of spines. Chronic but not acute administration of XBD173 ameliorates spatial learning deficits in transgenic AD mice with arctic mutation (ArcA{beta}) mice. The heterozygous TSPO-knockout crossed with the transgenic arctic mutation model of AD mice (het TSPOKO X ArcA{beta}) treated with XBD173 does not show this improvement in spatial learning suggesting TSPO is needed for procognitive effects of XBD173. The neuroprotective profile of XBD173 in AD pathology is further supported by a reduction in plaques and soluble A{beta} levels in the cortex, increased synthesis of neurosteroids, rescued spine density, reduction of complement protein C1q deposits, and reduced astrocytic phagocytosis of functional synapses both in the hippocampus and cortex. Our findings suggest that XBD173 may exert therapeutic effects via TSPO in a mouse model of AD.

neuroscience↗

bioRxiv2021

Revealing A-T and G-C Hoogsteen base pairs in stressed protein-bound duplex DNA

Watson-Crick base pairs (bps) are the fundamental unit of genetic information and the building blocks of the DNA double helix. However, A-T and G-C can also form alternative Hoogsteen bps, expanding the functional complexity of DNA. We developed Hoog-finder, which uses structural fingerprints to rapidly screen Hoogsteen bps, which may have been mismodeled as Watson-Crick in crystal structures of protein-DNA complexes. We uncovered seventeen Hoogsteen bps, seven of which were in complex with six proteins never before shown to bind Hoogsteen bps. The Hoogsteen bps occur near mismatches, nicks, and lesions and some appear to participate in recognition and damage repair. Our results suggest a potentially broad role for Hoogsteen bps in stressed regions of the genome and call for a community-wide effort to identify these bps in current and future crystal structures of DNA and its complexes.

biophysics↗

bioRxiv2019

Placental neurosteroids shape cerebellar development and social behaviour

Compromised placental function or premature loss has been linked to diverse neurodevelopmental disorders 1,2. The placenta is the first functional foetal endocrine organ, but the direct impact of placental hormone loss on foetal brain in late gestation has not been empirically tested. Allopregnanolone (ALLO) is a non-glucocorticoid, progesterone derivative that acts as a positive modulator of GABA-A receptor activity3 with the potential to alter critical GABA-mediated developmental processes 4,5. To directly test the role of placental ALLO, we generated a novel mouse model in which the gene encoding the synthetic enzyme for ALLO (Akr1c14) is specifically deleted in trophoblasts using a tissue-specific Cre-Lox strategy. ALLO concentrations are significantly decreased in late gestation in placenta and brain when placental Akr1c14 is removed, indicating placenta as the primary gestational ALLO source. We now demonstrate that targeted placental ALLO loss leads to permanent changes in brain development in a sex- and regionally-specific manner. Placental ALLO insufficiency led to male-specific cerebellar white matter (WM) abnormalities characterized by excess myelination with increased myelin protein expression, similar to changes reported in boys with autism spectrum disorders (ASD)6,7. Behavioural testing of these mice revealed increased repetitive behaviour and sociability deficits, two hallmarks of ASD, only in male offspring with placental ALLO insufficiency. Notably, a strong positive correlation was seen between the cerebellar contents of myelin basic protein (MBP) and the severity of ASD-like behaviours. A single injection of ALLO during gestation was sufficient to rescue both cerebellar MBP levels and aberrant behaviours. This study reveals a new role for a placental hormone in shaping specific brain structures and behaviours, and suggests that identifying placental hormone insufficiency or preterm loss may offer novel therapeutic opportunities to prevent later neurobehavioural disorders.

neuroscience↗