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Hoffmann, L.

Publications and source records attributed to Hoffmann, L..

16 recordsLinked to original sources

In which cases does it make sense to classify an individual into one population and what are the alternatives?

During biogeographical ancestry (BGA) analysis, an unknown individual for whom ancestry informative markers (AIMs) were analyzed is often assigned to one of a few reference populations. For some individuals, such an assignment is not meaningful: the two parents of the individual may come from different populations, or the individual may come from a population not included in the reference database. In this study, we examined classification methods in combination with 104 AIMs from the VISAGE Enhanced Tool to provide one of the following three possible outcomes: (i) in-reference (IR), with an assignment to one of the reference populations; (ii) admixed (AD), with parents from two in-reference populations; and (iii) out-of-reference (OR), where the individual's ancestry is not sufficiently represented by the reference populations. We therefore compared seven classifiers in combination with class-specific acceptance thresholds for the OR decision. The best-performing method according to our selection criterion was a naive Bayes classifier over pairs of populations, which we call the recent naive Bayes (RNB) classifier. Populations held out of the reference panel were correctly rejected in $84.9\%$ of cases. We further tested the method on $800$ individuals from seven additional groups not included in the reference panel. Only $29.4\%$ of individuals from four non-admixed populations were rejected, resembling joint ancestry with reference populations. In addition, we investigated the prediction accuracy in a newly collected dataset of 28 individuals with self-reported ancestry by analyzing AIMs using massively parallel sequencing.

genetics↗

The Mechanical Fingerprint of Hippocampal Sclerosis Linking Neuronal Cell Loss and Gliosis to Tissue Stiffness

Hippocampal sclerosis (HS) is the most common pathology in drug-resistant temporal lobe epilepsy (TLE). However, clinical diagnosis, prevalent epileptogenicity, and drug drug-resistance in individuals with HS remain an ongoing challenge demanding multidisciplinary research efforts. In this study, we examined the mechanical properties of neurosurgically en bloc resected HS specimens (n=8) ex vivo under compression, tension, and torsional shear. We fitted a two-term Ogden hyperelastic model to the measured mechanical responses to quantify nonlinear mechanical tissue properties. The resulting parameters revealed higher strain stiffening under compression in HS compared to hippocampus obtained post mortem (n=7). The distinction was most noticeable in the large-strain regime, which has important implications for using mechanical tissue properties as valuable diagnostic biomarker. Furthermore, we correlated the tissue microstructure with mechanical parameters. We trained a deep-learning histopathology classifier to detect and classify neurons and glial cells from hematoxylin-stained whole slide images (WSI). We identified a strong association between the small-strain stiffness (shear modulus {micro}) and the overall cell density as well as the glial cell density. The negative relationship between the neuron-to-glia ratio and shear modulus is consistent with the hypothesis that neuronal cell loss and gliosis drives tissue stiffening, respectively. Magnetic resonance imaging (MRI) analysis of the specimens confirmed the previously reported negative association between MRI-derived fractional anisotropy and shear modulus {micro}. Taken together, our study establishes a direct link between tissue mechanics and microstructure, suggesting nonlinear continuum mechanics models as promising new tools for clinical diagnosis and novel research strategies.

bioengineering↗

Neuronal precursor cell persistence in Ganglioglioma is associated with ECM remodeling and immune cell infiltration

BackgroundGangliogliomas (GGs) are low-grade glioneuronal tumors that frequently present with drug-resistant epilepsy. Although their indolent course contrasts with their high epileptogenic potential, the oncogenic mechanisms sustaining neuronal precursor-like populations within the tumor microenvironment remain poorly defined. MethodsWe performed spatial transcriptomic profiling on eight histologically confirmed GGs and matched healthy cortex to map the cellular and molecular architecture of the tumor microenvironment. Integrated analysis with weighted gene correlation network analysis (WGCNA) defined recurrent oncogenic programs and spatially resolved tumor-stroma interactions. ResultsEight conserved gene modules emerged, encompassing physiological cortical, reactive glial, and oncopathological programs. The latter captured extracellular matrix (ECM) remodeling, vascular-immune signaling, and persistence of immature, proliferative neuronal-like states. Spatial modeling revealed that these oncopathological programs form structured niches at the tumor-brain interface, where radial glia-derived neuronal-like tumor cells coexist with immune and stromal elements engaged in ECM turnover and cytokine signaling. ConclusionsGanglioglioma represents a hybrid glioneuronal neoplasm in which developmental neuronal programs are co-opted by tumor-associated stromal and immune cues. This convergence establishes a permissive oncogenic niche that sustains precursor-like tumor cells and provides a mechanistic basis for both the tumors benign growth and its intrinsic epileptogenicity. Key PointsO_LISpatial transcriptomics identifies reproducible transcriptional programs that define the ganglioglioma microenvironment. C_LIO_LITumor-associated regions show transcriptional programs consistent with immature neuronal states together with ECM remodelling and immune activity. C_LIO_LISingle-cell reference data indicate that immature neuronal programs in ganglioglioma resemble radial glia-derived developmental states. C_LI Importance of the StudyGanglioglioma is a low-grade glioneuronal tumor that combines benign growth with pronounced epileptogenicity, yet the molecular basis of this dual behavior remains poorly understood. Through spatial transcriptomics integrated with single-cell analysis, we reveal that ganglioglioma architecture is defined by two interacting transcriptional axes: a residual glioneuronal network and a tumoral niche enriched for extracellular-matrix, vascular, and immune programs. Within these niches, immature neuronal-like tumor cells persist in a developmentally arrested state maintained by ECM-immune signaling. This spatially organized interplay between physiological and pathological programs explains both the low oncologic aggressiveness and high excitability of these lesions. Our findings provide molecular signatures that may refine diagnostic classification within the LEAT spectrum, delineate epileptogenic zones, and identify candidate pathways for therapeutic modulation of the ganglioglioma microenvironment.

neuroscience↗

Aberrant FICD-mediated AMPylation drives α-Synuclein pathology and overall protein dyshomeostasis in dopaminergic neurons in Parkinson's disease

BackgroundFilamentation induced by cAMP domain-containing protein (FICD) is an endoplasmic reticulum (ER)-resident adenylyltransferase that catalyzes protein AMPylation, a post-translational modification. Although FICD-mediated AMPylation has been linked to the fine-tuning of proteostasis and neuronal integrity, its role in neurodegenerative diseases characterized by protein dyshomeostasis remains unclear. Parkinsons disease (PD) is defined by dopaminergic neurodegeneration and aggregation of -synuclein (aSyn) as a consequence of impaired protein homeostasis. We therefore investigated whether dysregulated FICD-mediated AMPylation contributes to PD pathogenesis. MethodsWe combined analyses of human post-mortem PD brain tissue with complementary models, including midbrain dopaminergic neurons derived from human induced pluripotent stem cells (hiPSCs) of a PD patient carrying an SNCA gene duplication and its isogenic gene dosage-corrected control line, transgenic mouse models of synucleinopathy, and an aSyn-overexpressing H4 neuroglioma cell model. Genetic and pharmacological modulation of FICD activity was integrated with multi-proteomic approaches, including chemical proteomics-based AMPylation profiling, stable isotope labelling with amino acids in cell culture-based global protein turnover analysis, and whole-proteome profiling to identify AMPylation-associated molecular pathways. ResultsFICD was preferentially expressed in dopaminergic neurons and was upregulated in SNCA duplication PD patient-derived neurons, as well as in the basal ganglia of PD post-mortem brains and synucleinopathy mice. Despite this overall increase, the proportion of FICD-expressing dopaminergic neurons was reduced under PD conditions, suggesting selective vulnerability of dopaminergic neurons to FICD. Mechanistically, FICD selectively AMPylated lysosomal proteins, thereby linking AMPylation to the regulation of degradative pathways. Moreover, hyperactivation of FICD-induced AMPylation triggered ER stress, impaired lysosomal function, reduced protein turnover, and ultimately promoted aSyn aggregation and apoptotic cell death. Importantly, pharmacological inhibition of AMPylation reversed aSyn pathology and neurite degeneration in PD patient-derived neurons. ConclusionsWe identify the pathological relevance of FICD-mediated AMPylation in PD-related neurodegeneration and its contribution to aSyn aggregation through a bidirectional interplay with aSyn pathology. Our findings support FICD-mediated AMPylation as a defining molecular switch regulating intracellular protein homeostasis in PD and highlight the FICD-AMPylation pathway as a potential therapeutic target for restoring aSyn pathology and mitigating disease progression.

neuroscience↗

Click. Screen. Degrade. A Miniaturized D2B Workflow for rapid PROTAC Discovery

Targeted protein degradation is one of the fastest developing fields in medicinal chemistry and chemical biology. Despite significant development in assay technologies and inhibitor discovery, the development of PROTACs remains a challenging endeavor since rational design approaches remain widely elusive. Our workflow eliminates the rate-limiting step of classic synthesis, namely compound purification, and pairs it with high-throughput, semi-automated plate-based synthesis, and direct cellular assay evaluation. We applied this direct-to-biology approach to four diverse targets demonstrating the general applicability of this technology. PROTAC synthesis was realized by using the highly efficient copper-catalyzed azide-alkyne cycloaddition reaction. This simplified reaction setup allowed synthesis in the nanomole scale with reaction volumes as low as 5 L. This high throughput approach enables the synthesis and testing of hundreds of PROTACs within a few days, allowing for a comprehensive assessment of target degradability and the identification of the most suitable E3 ligase for degrader development.

biochemistry↗

AMPylation regulates PLD3 processing.

The 5-3 exonuclease phospholipase D3 (PLD3) is a single-pass transmembrane protein undergoing sequential post-translational modifications (PTM) by N-glycosylation, AMPylation and proteolytic cleavage. The substrates of PLD3 5-3 exonuclease activity are single-stranded DNAs and RNAs, which act as ligands for Toll-like receptors (TLRs) and trigger a downstream pro-inflammatory response. Although PLD3 has primarily been studied in immune cells, recent findings indicate its enrichment in neurons, where it plays a role in regulating axonal fitness in Alzheimers disease (AD). However, the regulatory mechanisms governing the proteolytic processing of PLD3 into its catalytically active soluble form and its functional roles in both immune and neuronal cells remain unclear. Here, we describe the functional implications of PLD3 AMPylation, its direct interaction with the protein adenylyltransferase FICD, and changes in PLD3 processing in Parkinsons disease (PD) patient-derived neurons. We identified PLD3 AMPylation sites within the proteins soluble region and show that mutation of these sites lead to loss of PLD3 exonuclease catalytic activity. FICD AMP-transferase accelerates PLD3 degradation and induces cellular stress response. Furthermore, depletion of the two human AMP-transferases FICD and SelO point towards a complex regulatory network governing PLD3 AMPylation. Together, our findings demonstrate a critical role of AMPylation in PLD3 processing and regulation of its catalytic activity and provide new insights into the proteins transport and localization to lysosomes. The observation that PLD3 regulation in PD-derived neurons is altered compared to healthy neurons further highlights its role in neurodegenerative diseases.

biochemistry↗

MUTE drives asymmetric divisions to form stomatal subsidiary cells in Crassulaceae succulents

Amongst the evolutionary innovations of many succulents is a photosynthetic lifestyle, where stomatal gas exchange is decoupled from light-dependent carbon fixation. Stomatal complexes in the emerging succulent model Kalanchoe laxiflora consist of two guard cells surrounded by three anisocytic subsidiary cells (SCs). Here, we show that these SCs shuttle ions and thus likely support stomatal movements. Furthermore, gene editing, reporter lines and protein overexpression implicate the stomatal transcription factor MUTE in facilitating additional rounds of asymmetric divisions that form SCs in succulents. This is opposite to the role of MUTE in Arabidopsis thaliana, where it stops rather than induces asymmetric divisions, but reminiscent of MUTEs SC-related function in grasses. Together, our work deciphers an intricate genetic mechanism that generates innovative stomatal morphology in Crassulaceae succulents.

plant biology↗

3D Microphysiological Tumor Model for Dual-Targeting CAR T Cell Immunotherapy

The efficiency of immunotherapy stays limited for solid tumors. It is mainly caused by the tumoral structural heterogeneity and its complex microenvironment, which impede the infiltration of immune cells into malignant tissues. Mimicking this environment in frames of microphysiological models remains a challenge, significantly increasing costs of the clinical translation for the new therapies. Here, we study a 3D multi-spheroid model incorporating prostate stem cell antigen (PSCA) modified PC3 human prostate cancer cells and fibroblast activation protein (FAP) expressing fibrosarcoma HT1080 cells embedded within the soft hydrogel microbeads. We use this model to trial the immunotherapy based on the universal chimeric antigen receptor (UniCAR) T cells, and to better understand the impact of FAP on the immunotherapeutic treatment of solid tumors. First, we demonstrate the successful chemoattraction and infiltration of UniCAR T cells into the area of solid tumors, as well as the ability of UniCAR T cells to navigate through artificial extracellular matrix barriers. We further observe the synergistic efficacy of a dual-targeting UniCAR T cell approach against FAP and PSCA antigens, which represent the tumor microenvironment and the tumor, respectively. The results of our studies offer valuable methodologies and insights for engineering different 3D tumor models and studying immunotargeting of small-sized solid tumors (e.g., metastases and residual tumors). The developed microphysiological system has great potential to advance cancer research efforts aiming to elucidate the pivotal role of microenvironment in solid tumor development, enabling therapy trials and more precise prognosis for patients.

bioengineering↗

Preclinical Pediatric Molecular Analysis for Therapy Choice (MATCH)

Pediatric solid tumors arise from diverse tissues during development and exhibit a wide range of molecular, cellular and genetic features. This diversity, combined with the low incidence of pediatric cancer makes it increasingly difficult to personalize therapy for individual patients based on the unique features of their tumors. Therefore, well-credentialed preclinical models that capture the diversity and heterogeneity of pediatric solid tumors are essential for identifying molecular targeted therapeutics for precision medicine. Here, we report 281 orthotopic patient derived xenografts (O-PDXs) from 224 patients representing 24 different types of pediatric solid tumors. We have performed genomic characterization of the O-PDXs and compared them to their corresponding patient tumors. To demonstrate the feasibility and utility of using such a diverse collection of O-PDXs in preclinical studies, we performed a preclinical pediatric precision medicine trial based on the NCI-COG Pediatric MATCH trial enrollment criteria. We also tested molecular targeted therapy for a novel oncogenic fusion recently reported in pediatric melanoma and precision drug delivery using nano-liposomal irinotecan. Our studies demonstrate the value of large, well-credentialed preclinical models for future precision medicine in pediatric oncology using single agents, drug combinations and novel drug formulations. Translational RelevanceThis study demonstrates the value of utilizing fully characterized preclinical models of pediatric solid tumors to evaluate the response to precision medicine approaches. Our results demonstrate the importance of performing comprehensive preclinical testing using multiple orthotopic patient derived xenografts to validate and prioritize vulnerabilities identified through genomic or integrated analyses which can be translated into clinical trials. Importantly, this study identified combinations using nano-liposomal irinotecan in a precision drug delivery approach that may benefit pediatric solid tumor patients. In addition, all models and their associated data are made freely available to the scientific community through the Childhood Solid Tumor Network.

cancer biology↗

The ABC transporter MsbA in a dozen environments

High-resolution structure determination of membrane proteins typically requires isolation from the native lipid bilayer and reconstitution into artificial membrane mimics. For this purpose, numerous detergents, amphipols, polymers and membrane scaffold proteins are available. The choice of the specific membrane substitute can strongly affect the proteins specific activity, stability and conformational spectrum, potentially leading to errors or misinterpretation during analysis. The bacterial ATP-binding cassette transporter MsbA is a prominent example of such environment-specific bias, resulting in apparent conformational and activity responses. Here, we present a systematic analysis of the conformational spectrum of MsbA, stabilized in a dozen environments, using cryo-EM. Our data show pronounced structural feedback of the ABC transporter to the respective membrane mimetics. Detergents generally favour a conformation with wide separation of the nucleotide-binding domains, while nanodiscs induce the narrow conformation. Notably, only three of the dozen tested environments allow MsbA to sample the functional conformational spectrum, enabling full movement of the nucleotide-binding domains between narrow and wide inward-facing conformations. We expect this study to serve as a blueprint for other membrane proteins, even where the structural reaction to the hydrophobic environment is not directly visible but still critical for the proteins function.

molecular biology↗

Ena/VASP proteins at the crossroads of actin nucleation pathways in dendritic cell migration

As sentinels of our immune system dendritic cells (DCs) rely on efficient cell migration for patrolling peripheral tissues and delivering sampled antigens to secondary lymphoid organs for the activation of T-cells. Dynamic actin polymerization is key to their macropinocytic and migratory properties. Both major actin nucleation machineries, formins and the Arp2/3 complex, are critical for different aspects of DC functionality, by driving the generation of linear respectively branched actin filaments. However, the importance of a third group of actin nucleators, the Ena/VASP family, has not been addressed yet. Here, we show that the two family members Evl and VASP are expressed in murine DCs and that their loss negatively affects DC macropinocytosis, spreading, and migration. Our interactome analysis reveals Ena/VASP proteins to be ideally positioned for orchestrating the different actin nucleation pathways by binding to the formin mDia1 as well as to the WAVE regulatory complex, a stimulator of Arp2/3. In fact, Evl/VASP deficient murine DCs are more vulnerable to inhibition of Arp2/3 demonstrating that Ena/VASP proteins contribute to the robustness and efficiency of DC migration.

cell biology↗

Archival influenza virus genomes from Europe reveal genomic and phenotypic variability during the 1918 pandemic

The 1918 influenza pandemic was the deadliest respiratory pandemic of the 20th century and determined the genomic make-up of subsequent human influenza A viruses (IAV). Here, we analyze the first 1918 IAV genomes from Europe and from the first, milder wave of the pandemic. 1918 IAV genomic diversity is consistent with local transmission and frequent long-distance dispersal events and in vitro polymerase characterization suggests potential phenotypic variability. Comparison of first and second wave genomes shows variation at two sites in the nucleoprotein gene associated with resistance to host antiviral response, pointing at a possible adaptation of 1918 IAV to humans. Finally, phylogenetic estimates based on extended molecular clock modelling suggests a pure pandemic descent of seasonal H1N1 IAV as an alternative to the hypothesis of an intrasubtype reassortment origin. One Sentence SummaryMuch can be learned about past pandemics by uncovering their footprints in medical archives, which we here demonstrate for the 1918 flu pandemic.

microbiology↗

Photoperiod Sensitive Energy Sorghum Responses to Environmental and Nitrogen Variabilities

Recently introduced photoperiod-sensitive (PS) biomass sorghum (Sorghum bicolor L. Moench) needs to be investigated for their yield potentials under different cultivation environments with reasonable nitrogen (N) inputs. The objectives of this study were to 1) evaluate the biomass yield and feedstock quality of four sorghum hybrids with different levels of PS ranging from very PS (VPS) hybrids and to moderate PS (MPS) hybrids, and 2) determine the optimal N inputs (0~168 kg N ha-1) under four environments: combinations of both temperate (Urbana, IL) and subtropical (College Station, TX) regions during 2018 and 2019. Compared to TX, the PS sorghums in central IL showed higher yield potential and steady feedstock production with an extended daylength and with less precipitation variability, especially for the VPS hybrids. The mean dry matter (DM) yields of VPS hybrids were 20.5 Mg DM ha-1 and 17.7 Mg DM ha-1 in IL and TX, respectively. The highest N use efficiency occurred at a low N rate of 56 kg N ha-1 by improving approximately 33 kg DM ha-1 per 1.0 kg N ha-1 input. Approximately 70% of the PS sorghum biomass can be utilized for biofuel production, consisting of 58-65% of the cell wall components and 4-11% of the soluble sugar. This study demonstrated that the rainfed temperate area (e.g., IL) has a great potential for the sustainable cultivation of PS energy sorghum due their observed high yield potential, stable production, and low N requirements.

plant biology↗

Interrogation of SLFN11 in pediatric sarcomas uncovers an unexpected biological role and a novel therapeutic approach to overcoming resistance to replicative stress

Pediatric sarcomas represent a heterogeneous group of malignancies that exhibit variable response to DNA damaging chemotherapy. Schlafen family member 11 protein (SLFN11) increases sensitivity to replicative stress, and SLFN11 gene silencing has been implicated as a common mechanism of drug resistance in tumors in adults. We found SLFN11 to be widely expressed in our cohort of pediatric sarcomas. In sarcoma cell lines, protein expression strongly correlated with response to the PARP inhibitor talazoparib (TAL) and the topoisomerase I inhibitor irinotecan (IRN), with SLFN11 knockout resulting in significant loss of sensitivity in vitro and in vivo. However, SLFN11 expression was not associated with favorable outcomes in a retrospective analysis of our patient cohort; instead, the protein was retained and promoted tumor growth and evasion. Furthermore, we show that pediatric sarcomas develop resistance to TAL and IRN through impaired intrinsic apoptosis, and that resistance can be reversed by selective inhibition of BCL-XL. Statement of SignificanceThe role of SLFN11 in pediatric sarcomas has not been thoroughly explored. In contrast to its activity in adult tumors, SLFN11 did not predict favorable outcomes in pediatric patients, was not silenced, and promoted tumor growth. Resistance to replicative stress in SLFN11-expressing sarcomas was reversed by selective inhibition of BCL-XL.

cancer biology↗

Cofilin1 oxidation links oxidative distress to mitochondrial demise and neuronal cell death

Many cell death pathways, including apoptosis, regulated necrosis and ferroptosis are relevant for neuronal cell death and share common mechanisms such as the formation of reactive oxygen species (ROS). However, which molecular signaling pathways contribute to related pathologies and how they are interconnected remains elusive. Here, we present the role of cofilin1 in regulating mitochondrial functions and neuronal impairment. Cofilin1 deletion in neuronal HT22 cells exerted increased mitochondrial resilience, assessed by quantification of mitochondrial ROS production, mitochondrial membrane potential and ATP levels. HT22 cells deficient for cofilin1 exhibited a profound glycolytic shift to meet their energy demand in conditions of erastin and glutamate toxicity, whereas control cells were metabolically impaired and underwent ferroptosis and oxytosis, respectively. Further, cofilin1 was confirmed as a key player in glutamate-mediated excitotoxicity in primary cortical neurons isolated from cofilin1flx/flx, CaMKII-Cre knock-out mice. Mitochondrial respiration and cell viability were significantly preserved in cofilin1-/- primary neurons under conditions of excitotoxicity. Using isolated mitochondria and recombinant cofilin1, we provide a further link to toxicity-related mitochondrial impairment mediated by oxidized cofilin1. Wildtype cofilin1 directly affected the mitochondrial membrane potential, mitochondrial ROS accumulation and mitochondrial respiration. The detrimental impact of cofilin1 on mitochondria depends on oxidation of cysteine residues at positions 139 and 147. Our findings show that the actin-regulating protein cofilin1 acts as a redox sensor in oxidative cell death pathways of ferroptosis and oxytosis, and also promotes glutamate excitotoxicity. Oxidized cofilin1 links ROS accumulation to mitochondrial demise and neuronal cell death. Protective effects by cofilin1 inhibition are particularly attributed to preserved mitochondrial integrity and function. Thus, interfering with the oxidation and pathological activation of cofilin1 may offer an effective therapeutic strategy in neurodegenerative diseases.

neuroscience↗

PB-kPRED: Knowledge-Based Prediction Of Protein Backbone Conformation Using A Structural Alphabet

Libraries of structural prototypes that abstract protein local structures are known as structural alphabets and have proven to be very useful in various aspects of protein structure analyses and predictions. One such library, Protein Blocks (PBs), is composed of 16 standard 5-residues long structural prototypes. This form of analyzing proteins involves drafting its structure as a string of PBs. Thus, predicting the local structure of a protein in terms of protein blocks is a step towards the objective of predicting its 3-D structure. Here a new approach, kPred, is proposed towards this aim that is independent of the evolutionary information available. It involves (i) organizing the structural knowledge in the form of a database of pentapeptide fragments extracted from all protein structures in the PDB and (ii) apply a purely knowledge-based algorithm, not relying on secondary structure predictions or sequence alignment profiles, to scan this database and predict most probable backbone conformations for the protein local structures.\n\nBased on the strategy used for scanning the database, the method was able to achieve efficient mean Q16 accuracies between 40.8% and 66.3% for a non-redundant subset of the PDB filtered at 30% sequence identity cut-off. The impact of these scanning strategies on the prediction was evaluated and is discussed. A scoring function that gives a good estimate of the accuracy of prediction was further developed. This score estimates very well the accuracy of the algorithm (R2 of 0.82). An online version of the tool is provided freely for non-commercial usage at http://www.bo-protscience.fr/kpred/.

bioinformatics↗