Biology subjects

Friedman, N.

Publications and source records attributed to Friedman, N..

At least 19 recordsLinked to original sources

bioRxiv2026

Hepatobiliary Progenitor-like Reprogramming in Liver Metastases

Metastatic progression requires cancer cells to adapt to the unique constraints of distant organ microenvironments, yet the mechanisms that drive organ-specific adaptations remain poorly understood. Here, we show that the liver actively rewrites metastatic cancer cell identity, driving tumor cells toward a hepatobiliary progenitor-like state. Through integrated transcriptomic, proteomic, metabolomic, and epigenomic analyses of patient-derived rapid-autopsy samples and experimental models, we identify this state as selectively enriched in liver metastases. It is characterized by co-activation of hepatic and biliary/progenitor regulators HNF4A and SOX9 and is observed across multiple epithelial cancers, indicating a conserved response to the hepatic niche. Mechanistically, hepatocyte-derived TGF-{beta} and hypoxia converge to activate a HIF-1-ACLY axis, increasing nuclear acetyl-coenzyme A availability and histone acetylation at hepatic lineage regulatory elements to drive hepatobiliary reprogramming. This coordinated niche-response program can be captured transcriptionally and is associated with inferior overall survival. Disruption of this pathway suppresses hepatic reprogramming and impairs liver metastatic fitness. These findings identify the liver as an active determinant of metastatic cell fate, linking microenvironmental signaling to metabolic and chromatin remodeling programs that enable lineage plasticity. More broadly, they reveal organ-specific reprogramming as a fundamental principle of metastasis and a therapeutic vulnerability in liver metastases.

cancer biology↗

bioRxiv2024

ChIP-seq of Urinary Cell-Free Chromatin Infers Tissue Origin and Detects Tumor-Derived Cell-Free DNA in Bladder Cancer

Urine contains fragments of cell-free DNA, which hold valuable molecular insights into the processes occurring within the urinary system and the whole body. It is unknown whether these fragments are in the form of chromatin, as in the cell of origin, and whether they maintain the cell of origin chromatin modifications. Here, we examine these questions using cell-free chromatin immunoprecipitation followed by sequencing (cfChIP-seq) on human urine. We demonstrate that we can capture cell-free nucleosomes (cf-nucleosomes) from urine and that these preserve multiple histone post-translational modifications indicative of activation and repression. By analyzing these modifications, we identified the primary tissues contributing to cf-nucleosomes in a cohort of healthy individuals. Notably, we observe distinct populations of circulating cf-nucleosomes in urine samples from healthy donors with a contribution from the kidney, which are not detected in matched urine exfoliated cells or matching plasma samples. We further show that, at most, a negligible amount of urine cf-nucleosomes originates from plasma, suggesting that kidney filtration excludes plasma-circulating nucleosomes from urine. Additionally, we show that urine cf nucleosomes can report pathologically driven changes in the urine of bladder cancer patients, reflecting tumor-associated transcriptional programs and immune responses. Our findings highlight the potential of urine cf nucleosomes as accessible, noninvasive biomarkers for both basic research in renal physiology and monitoring urinary pathologies. Key FindingsO_LIUrine cell-free nucleosomes exist and retain multiple histone marks that are informative of gene promoters and enhancers. C_LIO_LIUrine cfChIP-seq identifies bladder, kidney, and immune cells as the major contributing organs to the pool of urine cell-free nucleosomes. C_LIO_LIThe populations of cell-free nucleosomes in urine and blood are distinct and primarily disjoint, suggesting that few, if any, nucleosomes cross the blood-urine interface. C_LIO_LIUrine cell-free nucleosomes reflect pathologically driven changes in tumors and immune cells responding to the tumor. C_LI

genomics↗

bioRxiv2024

TGFβ determines morphology and key cellular processes of activated CD4+ T cells

During an immune response, cells are simultaneously exposed to multiple cytokine signals that collectively determine their phenotype. Transforming growth factor {beta} (TGF{beta}) is a pleiotropic cytokine acting as a key regulator of T-cell differentiation with activating and suppressive effects on their immune function. Here, we systematically analyze the cellular responses of CD4+ T cells to TGF{beta} across diverse cytokine environments in the presence or absence of TGF{beta}. We found that TGF{beta} had a profound dominant effect independent of the presence of other cytokines, modulating the expression of more than 4,000 genes. In the presence of TGF{beta}, cells exhibit lower expression of translation-related and apoptosis-related genes, accompanied by increased survival of activated T cells. Notably, cells cultured in the presence of TGF{beta} were smaller in size while preserving their proliferative ability. Accordingly, we identified a dense network of transcription factors that were modulated by TGF{beta}, suggesting a core gene set connecting TGF{beta} signaling to the regulation of T-cell size. We found N-Myc to be at the center of this network, and we directly show that TGF{beta} regulates its gene expression level, protein level, and nuclear localization. Our work provides a system to study cell size control and demonstrate the profound effect of TGF{beta} in the modulation and regulation of T-cell properties, expanding its role beyond guiding their phenotype. Significance StatementTGF{beta} is a key determinant of CD4+ T-cell differentiation; however, understanding its effect on additional aspects of T-cell state is lacking. Here, we systematically studied the role of TGF{beta} in regulating T-cell physiology. Exposing cells to diverse combinations of cytokines enabled us to distill the core effect of TGF{beta}. We found TGF{beta} to have a profound effect on multiple cellular processes critical to T-cell function. Significantly, TGF{beta} induced smaller T-cells both in vitro and in vivo, suggesting that TGF{beta} could skew the population towards tissue infiltration and residency. Furthermore, TGF{beta} can be used to fine-tune T-cell size, providing a system for studying cell size control. Overall, our findings demonstrate the profound effect of TGF{beta} in the regulation of T-cell physiology.

immunology↗

bioRxiv2024

Worldwide soundscape ecology patterns across realms

Abstract and keywordsO_ST_ABSAimC_ST_ABSThe urgency for remote, reliable, and scalable biodiversity monitoring amidst mounting human pressures on ecosystems has sparked worldwide interest in Passive Acoustic Monitoring (PAM), which can track life underwater and on land. However, we lack a unified methodology to report this sampling effort and a comprehensive overview of PAM coverage to gauge its potential as a global research and monitoring tool. To remediate this, we created the Worldwide Soundscapes project, a collaborative network and growing database comprising metadata from 409 datasets across all realms (terrestrial, marine, freshwater, and subterranean). LocationWorldwide, 12 200 sites, all ecosystems. Time period1991 to present. Major taxa studiedAll soniferous taxa. MethodsWe synthesise sampling coverage across spatial, temporal, and ecological scales using metadata describing sampling locations, deployment schedules, focal taxa, and recording parameters. We explore global trends in biological, anthropogenic, and geophysical sounds based on 168 recordings from twelve ecosystems across all realms. ResultsTerrestrial sampling is spatially denser (45 sites/Mkm2) than aquatic sampling (0.3 and 1.8 sites/Mkm2 in oceans and fresh water) with only two subterranean datasets. Although diel and lunar cycles are well-covered in all realms, only marine datasets (56%) comprehensively sample all seasons. Across twelve ecosystems, biological sounds show contrasting diel patterns, decline with distance from the equator and negatively correlate with anthropogenic sounds. Main conclusionsPAM can inform macroecology studies as well as global conservation and phenology syntheses, but representation can be improved by expanding terrestrial taxonomic scope, sampling coverage in the high seas and subterranean ecosystems, and spatio-temporal replication in freshwater habitats. Overall, this global PAM network holds promise to support global biodiversity research and monitoring efforts.

ecology↗

bioRxiv2024

Molecular mechanisms underlying the modulation of T-cell proliferation and cytotoxicity by immobilized CCL21 and ICAM1

BackgroundAdoptive cancer immunotherapy, using engineered T-cells, expressing chimeric antigen receptor (CARs) or autologous tumor infiltrating lymphocytes (TILs) became, in recent years, a major therapeutic approach for diverse types of cancer. However, despite the transformative potential of adoptive cancer immunotherapy, this field still faces a major challenge manifested by the complex interplay between the proliferation rate and cytotoxic capacity of effector CD8+ T cells. MethodsWe performed integrated analysis of specific differentiation markers via flow cytometry, together with gene expression profiling to explore the molecular mechanisms through which a "synthetic immune niche" (SIN), composed of immobilized CCL21 and ICAM1, modulates the interplay between the proliferation and cytotoxic potency of effector CD8+ T cells. ResultsOn day 3, the transcriptomic effect induced by the SIN was largely similar for both DC/OVA and anti CD3/CD28-activated cells. Cell proliferation increased and the cells exhibited high killing capacity. On day 4 and on, the proliferation/cytotoxicity phenotypes were radically "activation-specific"; The DC/OVA-activated cells lost their cytotoxic activity, which, in turn, was rescued by the SIN treatment. Upon longer incubation, the cytotoxic activity further declined, and on day7, could not be rescued by the SIN. SIN stimulation following activation with antiCD3/CD28 beads resulted in a highly proliferative phenotype with low cytotoxicity, yet the cells regained killing activity on day 7. Potential molecular regulations of the SIN effects were identified, based on transcriptomic and multispectral imaging profiling. ConclusionsThese data indicate that cell proliferation and cytotoxicity are negatively correlated, and the interplay between them is differentially regulated by the mode of initial activation. The SIN stimulation greatly enhanced the cell expansion, following both activation modes, while maintaining high cytotoxic potency, suggesting that it could reinforce adoptive cancer immunotherapy.

immunology↗

bioRxiv2024

Continuous structural neuroplasticity during motor learning - a diffusion MRI study

How does our brain transform when we encounter a new task? To fully answer this question, comparing brain states before and after learning may not be enough, but rather an on-going, continuous monitoring of brain changes during learning is required. While such continuous examinations of functional learning-induced changes are widely available using functional magnetic resonance imaging (fMRI), a continuous investigation of microstructural brain modifications during learning is yet to be reported. Here, we continuously acquire diffusion MRI images during task performance. We then compute the mean diffusivity (MD) using a sliding-window approach, resulting in a continuous measure of microstructural changes throughout learning. We demonstrate the utility of this method on a motor sequence learning (finger tapping) task (n=58). MD decrease was detected in task-related brain regions, including the parahippocampal gyrus, hippocampus, inferior temporal gyrus, and cerebellum. Analysis of the temporal patterns of decrease revealed a rapid MD reduction in the right temporal gyrus after 11 minutes of learning, with additional decrease in the right parahippocampal gyrus and left cerebellum after 22 minutes. We further computed "neuroplasticity networks" of brain areas showing similar change patterns and detected similarities between these networks and canonical functional connectivity networks. Our findings offer novel insights on the spatio-temporal dynamics of microstructural neuroplasticity by demonstrating continuous modifications during the encoding phase of learning itself, rather than comparing pre- and post-learning states.

neuroscience↗

bioRxiv2023

Towards a Brighter Constellation: Multi-Organ Neuroimaging of Neural and Vascular Dynamics in the Spinal Cord and Brain

SignificancePain is comprised of a complex interaction between motor action and somatosensation that is dependent on dynamic interactions between the brain and spinal cord. This makes understanding pain particularly challenging as it involves rich interactions between many circuits (e.g., neural and vascular) and signaling cascades throughout the body. As such, experimentation on a single region may lead to an incomplete and potentially incorrect understanding of crucial underlying mechanisms. AimHere, we aimed to develop and validate new tools to enable detailed and extended observation of neural and vascular activity in the brain and spinal cord. The first key set of innovations were targeted to developing novel imaging hardware that addresses the many challenges of multi-site imaging. The second key set of innovations were targeted to enabling bioluminescent imaging, as this approach can address limitations of fluorescent microscopy including photobleaching, phototoxicity and decreased resolution due to scattering of excitation signals. ApproachWe designed 3D-printed brain and spinal cord implants to enable effective surgical implantations and optical access with wearable miniscopes or an open window (e.g., for one-or two-photon microscopy or optogenetic stimulation). We also tested the viability for bioluminescent imaging, and developed a novel modified miniscope optimized for these signals (BLmini). ResultsHere, we describe novel universal implants for acute and chronic simultaneous brain-spinal cord imaging and optical stimulation. We further describe successful imaging of bioluminescent signals in both foci, and a new miniscope, the BLmini, which has reduced weight, cost and form-factor relative to standard wearable miniscopes. ConclusionsThe combination of 3D printed implants, advanced imaging tools, and bioluminescence imaging techniques offers a new coalition of methods for understanding spinal cord-brain interactions. This work has the potential for use in future research into neuropathic pain and other sensory disorders and motor behavior.

bioengineering↗

bioRxiv2023

Epigenetic liquid biopsies reveal elevated vascular endothelial cell turnover and erythropoiesis in asymptomatic COVID-19 patients

The full spectrum of tissues affected by SARS-CoV-2 infection is crucial for deciphering the heterogenous clinical course of COVID-19. Here, we analyzed DNA methylation and histone modification patterns in circulating chromatin to assess cell type-specific turnover in severe and asymptomatic COVID-19 patients, in relation to clinical outcome. Patients with severe COVID-19 had a massive elevation of circulating cell-free DNA (cfDNA) levels, which originated in lung epithelial cells, cardiomyocytes, vascular endothelial cells and erythroblasts, suggesting increased cell death or turnover in these tissues. The immune response to infection was reflected by elevated B cell and monocyte/macrophage cfDNA levels, and by evidence of an interferon response in cells prior to cfDNA release. Strikingly, monocyte/macrophage cfDNA levels (but not monocyte counts), as well as lung epithelium cfDNA and vascular endothelial cfDNA, predicted clinical deterioration and duration of hospitalization. Asymptomatic patients had elevated levels of immune-derived cfDNA but did not show evidence of pulmonary or cardiac damage. Surprisingly, these patients showed elevated levels of vascular endothelial cell and erythroblast cfDNA, suggesting that sub-clinical vascular and erythrocyte turnover are universal features of COVID-19, independent of disease severity. Epigenetic liquid biopsies provide non-invasive means of monitoring COVID-19 patients, and reveal sub-clinical vascular damage and red blood cell turnover.

microbiology↗

bioRxiv2023

A FRET-based excitatory luminopsin with improved efficacy of bioluminescence-driven activation

SignificanceBioluminescent optogenetics (BL-OG) offers a unique and powerful approach to manipulate neural activity both opto- and chemogenetically using a single actuator molecule (a LuMinOpsin, LMO). AimTo further enhance the utility of BL-OG by improving the efficacy of chemogenetic (bioluminescence- driven) LMO activation. ApproachWe developed novel luciferases optimized for Forster resonance energy transfer (FRET) when fused to the fluorescent protein mNeonGreen, generating bright bioluminescent (BL) emitters spectrally tuned to Volvox Channelrhodopsin 1 (VChR1). ResultsA new LMO generated from this approach (LMO7) showed significantly stronger BL-driven opsin activation compared to previous and other new variants. We extensively benchmarked LMO7 against LMO3 (current standard), and found significantly stronger neuronal activity modulation ex vivo and in vivo, and efficient modulation of behavior. ConclusionsWe report a robust new option for achieving multiple modes of control in a single actuator, and a promising engineering strategy for continued improvement of BL-OG.

neuroscience↗

bioRxiv2022

Modulating the proliferative and cytotoxic properties of human TIL by a synthetic immune niche of immobilized CCL21 and ICAM1

The major challenge in developing an effective adoptive cancer immunotherapy, is the ex-vivo generation of tumor-reactive cells, in sufficient numbers and with enhanced cytotoxic potential. It was recently demonstrated, that culturing of activated murine CD8+ T-cells on a "Synthetic Immune Niche" (SIN), consisting of immobilized CCL21 and ICAM-1, enhances T-cell expansion, increases cytotoxicity against cultured cancer cells and suppresses tumor growth in vivo [1, 2]. In the study reported here, we have tested the effect of the CCL21+ICAM1 SIN, on the expansion and cytotoxic phenotype of Tumor Infiltrating Lymphocytes (TIL), following activation with immobilized anti-CD3/CD28 stimulation, or commercial activation beads. The majority of TIL tested, displayed higher expansion when cultured on the coated SIN compared to cells incubated on uncoated substrate. Comparable enhancement of TIL proliferation was obtained by the CCL21+ICAM1 SIN, in a clinical setting that includes a 14-day rapid expansion procedure (REP), initiated with feeder cells, anti CD3 and IL-2. Co-incubation of post-REP TIL with matching target cancerous cells, demonstrated increased IFN{gamma} secretion beyond baseline in most of the TILs and a significant increase in granzyme B levels following activation on SIN. The SIN did not significantly alter the relative frequency of CD8/CD4 populations, as well as the expression of CD28, CD25 and several exhaustion markers. These results demonstrate the potential capacity of the CCL21+ICAM1 SIN to reinforce TIL-based immunotherapy.

immunology↗

bioRxiv2022

Subtyping of Small Cell Lung Cancer using plasma cell-free nucleosomes

Emerging data on small cell lung cancer (SCLC), an aggressive malignancy with exceptionally poor prognosis, support subtypes driven by distinct transcription regulators, which engender unique therapeutic vulnerabilities. However, the translational potential of these observations is limited by access to tumor biopsies. Here, we leverage chromatin immunoprecipitation of cell-free nucleosomes carrying active chromatin modifications followed by sequencing (cfChIP-seq) on 442 plasma samples from individuals with advanced SCLC, neuroendocrine carcinomas (NEC), non-SCLC cancers, and healthy adults. Beyond providing reliable estimates of SCLC circulating free DNA tumor fraction, cfChIP-seq captures the unique epigenetic states of SCLC tissue- and cell-of-origin. Comparison of cfChIP-seq signals to matched tumor transcriptomes reveals genome-wide concordance, establishing a direct link between gene expression in the tumor and plasma cell-free nucleosomes. Exploiting this link, we develop a classifier that discriminates between SCLC lineage-defining transcription factor subtypes based on cfChIP-seq data. This work sets the stage to non-invasively profile SCLC transcriptomes using plasma cfDNA histone modifications.

cancer biology↗

bioRxiv2022

From pseudotime to true dynamics: reconstructing a real-time axis for T cells differentiation

Numerous methods have recently emerged for ordering single cells along developmental trajectories. However, accurate depiction of developmental dynamics can only be achieved after rescaling the trajectory according to the relative time spent at each developmental point. We formulate a model which estimates local cell densities and fluxes, and incorporates cell division and apoptosis rates, to infer the real time dimension of the developmental trajectory. We validate the model using mathematical simulations, and apply it on experimental high dimensional cytometry data obtained from the mouse thymus to construct the true time-profile of the thymocyte developmental process. Our method can easily be implemented in any of the existing tools for trajectory inference.

systems biology↗

bioRxiv2022

Conserved degronome features governing quality control-associated proteolysis

The eukaryotic proteome undergoes constant surveillance by quality control systems that either sequester, refold, or eliminate aberrant proteins by ubiquitin-dependent mechanisms. Ubiquitin-conjugation necessitates the recognition of degradation determinants, termed degrons, by their cognate E3 ubiquitin-protein ligases. To learn about the distinctive properties of quality control degrons, we performed an unbiased peptidome stability screen in yeast. The search identified a large cohort of proteome-derived degrons, some of which exhibited broad E3 ligase specificity. Consequent application of a machine-learning algorithm established constraints governing degron potency, including the amino acid composition and secondary structure propensities. According to the set criteria, degrons with transmembrane domain-like characteristics are the most probable sequences to act as degrons. Similar quality control degrons were identified in viral and human proteins, suggesting conserved degradation mechanisms. Altogether, the emerging data indicate that transmembrane domain-like degron features have been preserved in evolution as key quality control determinants of proteins half-life.

cell biology↗

bioRxiv2022

Population based selection shapes the T cell receptor repertoire during thymic development

One of the feats of adaptive immunity is its ability to recognize foreign pathogens while sparing the self. During maturation in the thymus, T cells are selected through the binding properties of their antigen-specific T-cell receptor (TCR), through the elimination of both weakly (positive selection) and strongly (negative selection) self-reactive receptors. However, the impact of thymic selection on the TCR repertoire is poorly understood. Here, we use transgenic Nur77-mice expressing a T-cell activation reporter to study the repertoires of thymic T cells at various stages of their development, including cells that do not pass selection. We combine high-throughput repertoire sequencing with statistical inference techniques to charactarize the selection of the TCR in these distinct subsets. We find small but significant differences in the TCR repertoire parameters between the maturation stages, which recapitulate known differentiation pathways leading to the CD4+ and CD8+ subtypes. These differences can be simulated by simple models of selection acting linearly on the sequence features. We find no evidence of specific sequences or sequence motifs or features that are suppressed by negative selection. These results are consistent with a collective or statistical model for T-cell specificity, where negative selection biases the repertoire away from self recognition, rather than ensuring lack of self-reactivity at the single-cell level.

immunology↗

bioRxiv2021

Polyclonal lymphoid expansion drives paraneoplastic autoimmunity in neuroblastoma

Neuroblastoma is a lethal childhood solid tumor of developing peripheral nerves. Two percent of children with neuroblastoma develop Opsoclonus Myoclonus Ataxia Syndrome (OMAS), a paraneoplastic disease characterized by cerebellar and brainstem-directed autoimmunity, but typically with outstanding cancer-related outcomes. We compared tumor transcriptomes and tumor infiltrating T- and B-cell repertoires from 38 OMAS subjects with neuroblastoma to 26 non- OMAS associated neuroblastomas. We found greater B- and T-cell infiltration in OMAS- associated tumors compared to controls, but unexpectedly showed that both were polyclonal expansions. Tertiary lymphoid structures (TLS) were enriched in OMAS-associated tumors. We identified significant enrichment of the MHC Class II allele HLA-DOB*01:01 in OMAS patients. OMAS severity scores were associated with the expression of several candidate autoimmune genes. We propose a model in which polyclonal autoreactive B lymphocytes act as antigen presenting cells and drive TLS formation, thereby crucially supporting both sustained polyclonal T-cell-mediated anti-tumor immunity and paraneoplastic OMAS neuropathology.

cancer biology↗

bioRxiv2021

Transcription feedback dynamics in the wake of cytoplasmic degradation shutdown

In the last decade, multiple studies have shown that cells maintain a balance of mRNA production and degradation, but the mechanisms by which cells implement this balance remain unknown. Here, we monitored cells mRNA and nascent mRNA profiles immediately following an acute depletion of Xrn1 - the main 5-3 mRNA exonuclease - that was previously implicated in balancing mRNA levels. We captured the detailed dynamics of the cells adaptation to rapid degradation of Xrn1 and observed a significant accumulation of mRNA, followed by a delayed global reduction in nascent transcription and a gradual return to baseline mRNA levels. We present evidence that this transcriptional response is linked to cell cycle progression, and that it is not unique to Xrn1 depletion; rather, it is induced earlier when upstream factors in the 5-3 degradation pathway are perturbed. Our data suggest that the RNA feedback mechanism is cell-cycle-linked and monitors the accumulation of inputs to the 5-3 exonucleolytic pathway rather than its outputs.

cell biology↗

bioRxiv2021

Selective Control of Synaptically-Connected Circuit Elements by All-Optical Synapses

Understanding percepts, engrams and actions requires methods for selectively modulating synaptic communication between specific subsets of interconnected cells. Here, we develop an approach to control synaptically connected elements using bioluminescent light: Luciferase-generated light, originating from a presynaptic axon terminal, modulates an opsin in its postsynaptic target. Vesicular-localized luciferase is released into the synaptic cleft in response to presynaptic activity, creating a real-time Optical Synapse. Light production is under experimenter-control by introduction of the small molecule luciferin. Signal transmission across this optical synapse is temporally defined by the presence of both the luciferin and presynaptic activity. We validate synaptic Interluminescence by multi-electrode recording in cultured neurons and in mice in vivo. Interluminescence represents a powerful approach to achieve synapse-specific and activity-dependent circuit control during behavior in vivo.

neuroscience↗

bioRxiv2021

Antigen experience relaxes the organisational structure of the T cell receptor repertoire

The creation and evolution of the T cell receptor repertoire within an individual combines stochastic and deterministic processes. We systematically examine the structure of the repertoire in different T cell subsets in young, adult and LCMV infected mice, from the perspective of variable gene usage, nucleotide sequences and amino acid motifs. Young individuals share a high level of organization, especially in the frequency distribution of variable genes and amino acid motifs. In adult mice, this structure relaxes and is replaced by idiotypic evolution of the effector and regulatory repertoire. The repertoire of CD4+ regulatory T cells was more similar to naive cells in young mice, but became more similar to effectors with age. Finally, we observed a dramatic restructuring of the repertoire following infection with LCMV. We hypothesize that the stochastic process of recombination and thymic selection initially impose a strong structure to the repertoire, which gradually relaxes following asynchronous responses to different antigens during life.

immunology↗