Biology subjects

Bhaduri, A.

Publications and source records attributed to Bhaduri, A..

At least 19 recordsLinked to original sources

bioRxiv2026

A foundation model for brain organoid network dynamics uncovers intrinsic computation and convergent disease phenotypes

Brain organoids develop self-organizing neural networks that can be used to model neurodevelopment and disease. Here we introduce PULSE, a foundation model developed using over 900 hours of high-density microelectrode array recordings of in vitro and ex vivo neural tissue. We show that this single model can address two open questions: how disease-associated variants alter network development, and how naive circuits encode information. PULSE revealed accelerated network maturation in held-out human 16p11.2-deletion organoids. It also revealed a change in network coordination shared with SHANK3 deficiency. Because organoids develop without sensory input, they let us ask how circuits encode information before any representation is learned. Closed-loop control of a virtual inverted pendulum engaged existing spontaneous activity patterns rather than creating new ones. PULSE provides a common reference frame for neural circuits across genotypes, protocols and tasks.

neuroscience↗

bioRxiv2026

Exosome-Mediated Bidirectional Signaling Regulates Glioma Stem-Cell Homeostasis and Radiation-Induced Plasticity

Background: Glioblastoma (GBM) is an aggressive brain malignancy characterized by therapeutic resistance and frequent recurrence. Glioma-initiating cells (GICs), also known as glioma stem cells (GSCs), contribute to these features through self-renewal and resistance to genotoxic stress. Radiation therapy can paradoxically replenish the GIC compartment by inducing stem-like properties in non-stem glioma cells. We investigated whether exosomes mediate bidirectional communication that maintains the balance between GIC and non-stem populations at steady state and following irradiation. Methods: Exosomes were isolated from GIC-enriched gliomaspheres and differentiated monolayer cultures of the patient-derived GBM lines HK-374 and HK-390. Vesicles were characterized by transmission electron microscopy, nanoparticle analysis, and detection of CD63. Recipient cells were exposed to exosomes with or without 4 Gy irradiation. GIC abundance and function were evaluated using a ZsGreen-ornithine decarboxylase degron reporter, sphere-formation assays, and extreme limiting dilution analysis. Exosomal protein cargo was characterized by liquid chromatography-tandem mass spectrometry and Gene Ontology enrichment analysis. Single-cell RNA sequencing was used to evaluate changes in cellular composition upon exosome treatment. Results: Isolated vesicles displayed characteristic exosomal morphology, a mean diameter of 41.6 +/- 14.7 nm, and CD63 expression. Irradiation produced a 12-fold increase in GIC reporter-positive cells among initially reporter-negative differentiated cells. Gliomasphere-derived exosomes significantly and dose-dependently suppressed this radiation-induced phenotype conversion and reduced functional GIC frequency and self-renewal in both patient-derived lines. Conversely, exosomes from GIC-depleted monolayer cultures increased reporter-positive cells two- to three- fold and enhanced the frequency and self-renewal of existing GICs. Proteomic analysis identified 1,796 exosomal proteins, including 336 differentially abundant candidates. Gliomasphere-derived exosomes were enriched in proteins associated with translation, RNA binding, actin organization, cytoskeletal regulation, and intracellular trafficking. Monolayer-derived exosomes were enriched in extracellular-matrix and stem-cell-niche components, including NID2, LAMA5, LAMB1, LAMB2, LAMC1, THBS1, TGFBI, IQGAP3, and APOE. Single-cell transcriptomic analysis showed that gliomasphere-derived exosomes prevented the radiation-induced expansion of neural progenitor-like cells, consistent with suppression of an induced stem-like state. Treatment of gliomaspheres with monolayer-derived exosomes left their overall cellular composition largely but enriched MYC-target, E2F-target, and oxidative-phosphorylation programs, suggesting that increased sphere formation may partly reflect enhanced proliferative capacity. Conclusions: GBM cells use exosomes to establish a bidirectional feedback circuit between stem-like and differentiated tumor-cell compartments. GIC-derived exosomes constrain radiation-induced conversion of non-stem glioma cells into GICs, whereas differentiated-cell-derived exosomes promote a niche that supports GIC maintenance and self-renewal, potentially through expansion of a mixed-vascular-like population containing neurovascular progenitors. Whether exosomal IQGAP3 contributes to the expansion of this GIC population remains to be determined. These findings identify exosome-mediated intercellular communication as a potential mechanism regulating GBM cellular homeostasis, treatment resistance, and recurrence.

neuroscience↗

bioRxiv2026

A consensus atlas of human brain development defines cell type-specific maturation trajectories across the lifespan

Human neurodevelopment is a continuous process that begins prenatally and extends into postnatal life. Current transcriptomic datasets are limited, fragmented across analytical frameworks, precluding comprehensive reconstruction of cellular trajectories linking developmental states to mature cell types. Here we present a consolidated cellular-resolution transcriptomic atlas of human brain development from the onset of neurogenesis to adulthood, covering [~]2.2 million cells from 156 donors across nine studies. All data were reprocessed from raw sequencing reads and annotated within a unified cell-type taxonomy, enabling reliable mapping across the lifespan. Cell types were highly replicable across heterogeneous datasets, enabling us to chart their maturation and cortical layer localization over time. We identify dynamic gene programs predictive of cell-type maturation, validate gene modules tracking known fate transitions, and leverage our atlas scale to characterize rare populations, including microglia. This resource establishes a standardized reference of human brain development and maturation gene modules for future comparisons across model systems, species, and disease states.

neuroscience↗

bioRxiv2026

Glutamatergic neuron-tumor synapses shape human glioblastoma cell states through radial glia plasticity

Glioblastoma (GBM) is a devastating primary brain tumor with remarkable inter- and intra-tumoral heterogeneity. GBM cells assume a spectrum of neurodevelopmental-like phenotypes and co-opt normal neurophysiological processes, which include synaptic integration with their neuronal microenvironment. This is mediated by neuron-tumor synapses (NTS) that predominantly involve glutamatergic receptors, which drive calcium elevations that promote tumor proliferation and invasion. The exact relationship between synaptic signaling and tumor cell fate specification, however, remains largely unexplored. Here, we develop and leverage a synapse-optimized human organoid tumor transplantation (so-HOTT) model of GBM to decipher how glutamatergic signaling impacts GBM lineage trajectories. so-HOTT preserves patient tumor heterogeneity, features excitatory NTS, and enables clonal lineage tracing of tumor cells after NTS perturbations. Genetic and pharmacological inhibition of AMPA and kainate receptors in so-HOTT shifts tumor cell composition from neuronal fates toward progenitor-proximal astrocytic/mesenchymal states. This occurs through the attenuation of calcium signaling and reduced plasticity of malignant radial glia (RG)-like progenitors, a previously unrecognized target of NTS. Through the integration of inputs from the neuronal microenvironment into glutamatergic signaling, progenitor populations modulate their transcriptional programs and cell fate, ultimately shaping GBM tumor heterogeneity. Targeting synaptic input may thus constrain the heterogeneity that fuels GBM adaptation and therapeutic escape.

cancer biology↗

bioRxiv2026

Intrinsic coordination of dynamic molecular signatures shape the human prefrontal cortex

The cerebral cortex drives human cognition through the coordinated activity of discrete cortical areas, each harboring specialized molecular, structural and functional characteristics. Central to this organization is the prefrontal cortex (PFC), a hub for executive function that displays disproportionate expansion in humans and selective vulnerability to neurodevelopmental disorders. Previous work has identified a collection of PFC-enriched marker genes with dynamic expression trajectories, and re-analysis of these datasets converge these markers into 18 distinct molecular signatures of spatiotemporal PFC identity. However, the intrinsic gene networks that coordinate these molecular signatures to shape the human PFC remains unclear. Through pooled CRISPR activation screens in human primary cortical tissues, we have evaluated the ability of PFC-enriched transcription factors to intrinsically pattern PFC molecular identity. Our screens identify novel roles for the neurogenesis regulator, YBX1, in the activation of human PFC fate. In parallel screens and knock-down experiments in human cortical organoids, we define how YBX1 acts in concert with other PFC determinants to activate molecular signatures of PFC identity. Our findings support a model in which PFC patterning is orchestrated by cohorts of intrinsic determinants that initiate, potentiate, and modulate PFC gene signatures, conferring robustness to the development of the human PFC.

neuroscience↗

bioRxiv2026

Temporal Mapping of Radiation-Induced Neural Injury and Mitigation in Human Cortical Organoids

BackgroundRadiation therapy is a standard-of-care oncological treatment for central nervous system (CNS) malignancies. However, as survival outcomes improve, radiation-induced injury to normal brain tissue has increased in clinical significance. CNS radiation injury is a delayed, multifactorial process characterized by impaired neurogenesis, reactive gliosis, and persistent functional deficits. Mechanistic exploration and development of effective radiation mitigators have been limited by the lack of scalable, human-relevant models. MethodsMature human iPSC-derived cortical organoids were exposed to single-dose or clinically relevant fractionated radiation (5 x 2 Gy). DNA damage, apoptosis, and growth dynamics were assessed longitudinally. Structural organization, synaptic integrity, and neuroinflammatory responses were evaluated by immunofluorescence and real-time PCR. Transcriptomic profiling was performed at 72 hours and 2 weeks after fractionated radiation to capture acute and delayed effects. Two candidate radiation mitigators, NSPP and amisulpride, were tested for their therapeutic effects within the organoid system. ResultsCortical organoids exhibited partial recovery following single doses up to 4 Gy or fractioned irradiation. Transcriptomic analyses revealed that radiation not only reduced overall cell viability but also reshaped lineage trajectories, characterized by depletion of neural stem/progenitor populations, loss of neuronal identity, enhanced gliogenesis, increased inflammatory cytokines, and disrupted cortical layering and synaptic integrity. Treatment with NSPP or amisulpride attenuated injury-associated transcriptional and structural alterations. ConclusionHuman cortical organoids recapitulate key features of radiation-induced neural injury, recovery, and therapeutic modulation, providing a robust, scalable, and human-relevant platform for studying CNS radiation biology and preclinical screening of candidate radiation mitigators. Key pointsO_LIHuman iPSC-derived cortical organoids enable study of human CNS radiation responses. C_LIO_LIOrganoids recover after single-dose and fractionated radiation relevant to clinical exposure. C_LIO_LIThe platform supports scalable, human-relevant testing of radiation mitigation strategies. C_LI

cell biology↗

bioRxiv2026

Predictable clonal hierarchies from restricted progenitors provide a framework for cell type-specific therapies in glioblastoma

Extensive molecular profiling has revealed profound heterogeneity in glioblastoma (GBM), yet how cellular lineages organize over time to govern tumor propagation and therapeutic response remains poorly understood. Existing single-cell approaches define transcriptional states but provide limited insight into how clonal dynamics shape functional tumor behavior. Here, we integrate high-complexity combinatorial DNA barcoding with single-cell transcriptomics in direct-from-patient IDH1-wild-type GBM, enabling lineage-resolved mapping of progenitor organization in a human microenvironmental context. Across 235,155 malignant cells from nine tumors, clonal relationships form reproducible lineage tracks in which distinct progenitor populations give rise to specific differentiated cell types, revealing that tumor growth is sustained by multiple non-redundant progenitors rather than a single dominant population. These progenitors exhibit distinct propensities for self-renewal, fate restriction, and cross-compartment interactions, collectively accounting for the full spectrum of tumor states. Using this lineage-resolved framework, we identify complementary drug targets in distinct progenitor compartments and demonstrate that hierarchy-informed combination therapies disrupt progenitor-progenitor interactions and reshape lineage output. These findings move beyond descriptive heterogeneity to define functional logic underlying GBM propagation and establish a generalizable framework for rational, cell type-specific combinatorial therapies.

cancer biology↗

bioRxiv2025

Region-specific human brain organoids reveal synaptic and cell state drivers of glioblastoma invasion

Glioblastoma (GBM) is a highly heterogenous and malignant brain tumor, in part because it disrupts normal brain circuits to fuel its own growth and invasion. Thus, there is a need to identify the molecular features of invasive GBM cells and their regulators in the neural microenvironment. To address this in a fully human model, we engrafted patient-derived GBM cells (total n=15 independent samples) from three sources-- fresh neurosurgical resections, cell lines, and whole GBM organoids--into human induced pluripotent stem cell-derived organoids patterned to forebrain, midbrain, and spinal cord identities. GBM cells from all sources infiltrated brain organoids within 2 days post-engraftment, reaching maximal invasion by day 14. Across organoids of distinct spatial and maturational milieu, GBM cells showed a consistent reduction in astrocyte-like states and an enrichment in neuron/glia progenitor-like (NPC-like) states. These NPC-like GBM cells expressed neuronal and synaptic machinery, and tumors enriched in this transcriptomic state prior to engraftment achieved greater organoid coverage, suggesting enhanced infiltration and synaptic integration of this GBM cell type. Although GBM cell states converged across organoid types after engraftment, infiltration was greater in the forebrain than spinal cord. This is likely reflective of synaptic input from deep-layer TBR1 excitatory neurons in the forebrain, as demonstrated by a combination of rabies-based monosynaptic tracing and single-cell transcriptomics. In contrast, inhibitory neurons were the predominant synaptic partners of GBM in the spinal cord. Together, this fully human model of the neural-GBM connectome reveals how neuron-like GBM states and regionally distinct synaptic inputs cooperatively shape tumor invasion.

neuroscience↗

bioRxiv2025

Lead (Pb) exposure alters neural cell fate in the developing human brain

The heavy metal lead (Pb) is a developmental neurotoxicant associated with cognitive and behavioral deficits, but the cellular mechanisms underlying these impairments remain unclear. Here we show that prenatal Pb exposure biases human radial glia fate, prolonging neurogenesis and suppressing astrogenesis. We used hiPSC-derived cortical organoids, primary human fetal tissue, and in vivo xenografts to demonstrate that Pb exposure alters radial glial differentiation. Pb-exposed organoids contain a higher proportion of neurons and fewer astrocytes. We validated this differentiation bias in primary radial glia from human cortices (GW16-20), observing Pb-associated reductions in astrocyte commitment via genetic lineage tracing. This correlated with increased H3K27me3, a repressive histone modification deposited by the histone methyltransferase complex PRC2, suggesting epigenetic reprogramming as a mechanistic link between Pb and neural cell fate commitment. Our findings indicate that prenatal Pb exposure impacts lineage commitment in the developing brain, which may contribute to cognitive and behavioral impairment.

neuroscience↗

bioRxiv2025

A Human Tumor-Immune Organoid Model of Glioblastoma

A major obstacle to identifying effective therapies for the aggressive brain tumor glioblastoma is the lack of human-specific, immunocompetent models that reflect the human tumor microenvironment. To address this, we developed the immune-Human Organoid Tumor Transplantation (iHOTT) model. This is an autologous co-culture platform that integrates patient-derived tumor cells and matched peripheral blood mononuclear cells (PBMCs) within human cortical organoids, enabling the study of the patient-specific immune response to the tumor and tumor-immune interactions. This platform preserves tumor and immune populations, immune signaling, and cell-cell interactions observed in patient tumors. Treatment of iHOTT with pembrolizumab, a checkpoint inhibitor, mirrored cell type shifts and cell interactions observed in patients. TCR sequencing further revealed pembrolizumab-driven expansion of stem-like CD4-T-cell clonotypes exhibiting patient-specific repertoires. These findings establish iHOTT as a physiologically relevant platform for exploring autologous tumor-immune interactions and underscore the critical need for antigen-targeted strategies to enhance immunotherapy in glioblastoma.

cancer biology↗

bioRxiv2025

Thalamic NRXN1-Mediated Input to Human Cortical Progenitors Drives Upper Layer Neurogenesis

According to the protocortex hypothesis, extrinsic thalamic signaling is necessary for refining cortical areas and cell types, but the mechanism by which these inputs shape the development and expansion of the human cortex remains largely unexplored. We fuse cortical and thalamic organoids to study this process. Using single-nuclei RNA-sequencing and cellular imaging, we discover that thalamic signals during a critical period promote human cortical upper-layer neurogenesis. In assembloid models and human primary cortex, we find NRXN1 mediates thalamic axon contact with primate-enriched outer radial glia, driving developmental gene expression changes. Genetic perturbation of NRXN1 in thalamic neurons reduces these contacts and attenuates cortical upper-layer neurogenesis. These findings in human developmental models suggest a novel role for thalamic regulation of primate outer radial glia cell fate.

neuroscience↗

bioRxiv2025

Design and Biological Activity of a Novel Brain Penetrant Urea Compound Against Glioblastoma

Glioblastoma (GBM) remains the most lethal primary brain tumor, largely due to therapy-resistant glioma stem cells (GSCs) and the ability of non-stem cells to dedifferentiate under therapeutic pressure. We developed MXC-017, a novel urea-based compound that crosses the blood-brain-barrier, directly targets GSCs, and prevents radiation-induced GSC formation. Using click chemistry pull-down and mass spectrometry, we identified vimentin as the target of MXC-017, further validated by in silico docking. Global transcriptomic profiling (bulk RNA-seq) and single-cell RNA-seq analyses revealed MXC-017s efficacy with minimal off-target effects, supported by metabolic and kinome assays. Normal cell toxicity was negligible in fibroblasts, microglia, astrocytes, and murine neural progenitors. Maximum tolerated dose was identified and we observed significantly extended median survival in 17 PDOX GBM models when treated with MXC-017 plus radiation, benchmarked against standard-of-care temozolomide. These findings underscore the therapeutic potential of vimentin-targeting agents to overcome radiation resistance and improve outcomes for GBM patients. Statement of SignificanceGlioblastomas distinctive nature and the blood-brain barrier hamper therapies targeting therapy-resistant GSCs. We developed a novel urea-based agent that crosses the barrier, targets GSCs, and prevents radiation-induced GSC formation. With minimal off-target effects, reduced toxicity, and superior survival in PDOX models, it offers potential to improve outcome in GBM.

neuroscience↗

bioRxiv2025

IL-6 underlies microenvironment immunosuppression and resistance to therapy in glioblastoma

The glioblastoma tumor immune microenvironment (TIME) is an immunosuppressive barrier to therapy that encumbers glioblastoma responses to immune checkpoint inhibition (ICI). Immunosuppressive cytokines, pro-tumor myeloid cells, and exhausted T-cells are hallmarks of the glioblastoma TIME. Here we integrate spatial and single-cell analyses of patient-matched human glioblastoma samples before and after ICI with genetic, immunologic, single-cell, and pharmacologic studies in preclinical models to reveal that interleukin-6 (IL-6) inhibition reprograms the glioblastoma TIME to sensitize mouse glioblastoma to ICI and radiotherapy. Rare human glioblastoma patients who achieve clinical responses to ICI have lower pre-treatment IL-6 levels compared to glioblastomas who do not respond to ICI. Immune stimulatory gene therapy suppresses IL-6 tumor levels in preclinical murine models of glioblastoma. Furthermore, survival was longer in Il-6 knockout mice with orthotopic SB28 glioblastoma relative to wild-type mice. IL-6 blockade with a neutralizing antibody transiently sensitizes mouse glioblastoma to anti-PD-1 by increasing MHCII+ monocytes, CD103+ migratory dendritic cells (DCs), CD11b+ conventional DCs, and effector CD8+ T cells, and decreasing immunosuppressive Tregs. To translate these findings to a combination treatment strategy for recurrent glioblastoma patients, we show that IL-6 blockade plus ICI durably sensitizes mouse glioblastoma to high-dose radiotherapy.

cancer biology↗

bioRxiv2025

Metabolic Atlas of Early Human Cortex Identifies Regulators of Cell Fate Transitions

Characterization of cell type emergence during human cortical development, which enables unique human cognition, has focused primarily on anatomical and transcriptional characterizations. Metabolic processes in the human brain that allow for rapid expansion, but contribute to vulnerability to neurodevelopmental disorders, remain largely unexplored. We performed a variety of metabolic assays in primary tissue and stem cell derived cortical organoids and observed dynamic changes in core metabolic functions, including an unexpected increase in glycolysis during late neurogenesis. By depleting glucose levels in cortical organoids, we increased outer radial glia, astrocytes, and inhibitory neurons. We found the pentose phosphate pathway (PPP) was impacted in these experiments and leveraged pharmacological and genetic manipulations to recapitulate these radial glia cell fate changes. These data identify a new role for the PPP in modulating radial glia cell fate specification and generate a resource for future exploration of additional metabolic pathways in human cortical development.

neuroscience↗

bioRxiv2024

A three-dimensional histological cell atlas of the developing human brain

The human brain is believed to contain a full complement of neurons by the time of birth together with a substantial amount of the connectivity architecture, even though a significant amount of growth occurs postnatally. The developmental process leading to this outcome is not well understood in humans in comparison with model organisms. Previous magnetic resonance imaging (MRI) studies give three-dimensional coverage but not cellular resolution. In contrast, sparsely sampled histological or spatial omics analyses have provided cellular resolution but not dense whole brain coverage. To address the unmet need to provide a quantitative spatiotemporal map of developing human brain at cellular resolution, we leveraged tape-transfer assisted serial section histology to obtain contiguous histological series and unbiased imaging with dense coverage. Interleaved 20 thick Nissl and H&E series and MRI volumes are co-registered into multimodal reference volumes with 60 isotropic resolution, together with atlas annotations and a stereotactic coordinate system based on skull landmarks. The histological atlas volumes have significantly more contrast and texture than the MRI volumes. We computationally detect cells brain-wide to obtain quantitative characterization of the cytoarchitecture of the developing brain at 13-14 and 20-21 gestational weeks, providing the first comprehensive regional cell counts and characterizing the differential growth of the different brain compartments. Morphological characteristics permit segmentation of cell types from histology. We detected and quantified brain-wide distribution of mitotic figures representing dividing cells, providing an unprecedented spatiotemporal atlas of proliferative dynamics in the developing human brain. Further, we characterized the abundance and distribution of Cajal-Retzius cells, a transient cell population that plays essential roles in organizing glutamatergic cortical neurons into layers. Together, our study provides an unprecedented quantitative window into the developing human brain and the reference volumes and coordinate space should be useful for integrating spatial omics data sets with dense histological context.

neuroscience↗

bioRxiv2024

Glioblastoma Neurovascular Progenitor Orchestrates Tumor Cell Type Diversity

Glioblastoma (GBM) exhibits developmental programs and marked cellular heterogeneity, yet how these features are organized into connected lineage hierarchies remains unclear. Here we identify a rare tumor-intrinsic population, termed the neurovascular progenitor (NVP), that occupies an intermediate position between the major GBM organizational axes. NVP cells co-express neural progenitor and perivascular transcriptional features, are consistently detected across independent patient cohorts, retain canonical GBM copy-number alterations, and localize in situ in both vessel-associated and parenchymal niches. Using direct-from-patient lineage tracing in a human organoid tumor transplantation system, we show that individual NVP cells clonally generate both neural-like and mesenchymal/vascular-like malignant progeny, providing a concrete lineage link between states that are commonly considered mutually exclusive. Despite comprising [~]1% of tumor cells, NVP-derived lineages account for a majority of observed tumor cell types and disproportionately contribute to cycling compartments. Orthogonally, ablation of NVP-associated programs in an in vivo GBM model remodels tumor composition, elicits compensatory progenitor states, and significantly prolongs survival. Together, these findings position NVP as a fate-restricted yet highly influential lineage intermediate that serves as a functional bridge and organizational nexus within GBM hierarchies, linking population-level lineage architecture to the behavior of a specific progenitor cell type.

cancer biology↗

bioRxiv2024

Mixtures of Intrinsically Disordered Neuronal Protein Tau and Anionic Liposomes Reveal Distinct Anionic Liposome-Tau Complexes Coexisting with Tau Liquid-Liquid Phase Separated Coacervates

Tau, an intrinsically disordered neuronal protein and polyampholyte with an overall positive charge, is a microtubule (MT) associated protein, which binds to anionic domains of MTs and suppresses their dynamic instability. Aberrant tau-MT interactions are implicated in Alzheimers and other neurodegenerative diseases. Here, we studied the interactions between full length human protein tau and other negatively charged binding substrates, as revealed by differential-interference-contrast (DIC) and fluorescence microscopy. As a binding substrate, we chose anionic liposomes (ALs) containing either 1,2-dioleoyl-sn-glycero-3-phosphatidylserine (DOPS, -1e) or 1,2-dioleoyl-sn-glycero-3-phosphatidylglycerol (DOPG, -1e) mixed with zwitterionic 1,2-dioleoyl-sn-glycero-3-phosphatidylcholine (DOPC) to mimic anionic plasma membranes of axons where tau resides. At low salt concentrations (0 to 10 mM KCl or NaCl) with minimal charge screening, reaction mixtures of tau and ALs resulted in the formation of distinct states of AL-tau complexes coexisting with liquid-liquid phase separated tau self-coacervates arising from the polyampholytic nature of tau containing cationic and anionic domains. AL-tau complexes exhibited distinct types of morphologies. This included, large {approx}20-30 micron tau-decorated giant vesicles with additional smaller liposomes with bound tau attached to the giant vesicles, and tau-mediated finite-size assemblies of small liposomes. As the ionic strength of the solution was increased to near and above physiological salt concentrations for 1:1 electrolytes ({approx}150 mM), AL-tau complexes remained stable while tau self-coacervate droplets were found to dissolve indicative of breaking of (anionic/cationic) electrostatic bonds between tau chains due to increased charge screening. The findings are consistent with the hypothesis that distinct cationic domains of tau may interact with anionic lipid domains of the lumen facing monolayer of the axon plasma membrane suggesting the possibility of transient yet robust interactions at physiologically relevant ionic strengths.

biophysics↗

bioRxiv2024

Human-specific paralogs of SRGAP2 induce neotenic features of microglia structural and functional maturation

Microglia play key roles in shaping synaptic connectivity during neural circuits development. Whether microglia display human-specific features of structural and functional maturation is currently unknown. We show that the ancestral gene SRGAP2A and its human-specific (HS) paralogs SRGAP2B/C are not only expressed in cortical neurons but are the only HS gene duplications expressed in human microglia. Here, using combination of xenotransplantation of human induced pluripotent stem cell (hiPSC)-derived microglia and mouse genetic models, we demonstrate that (1) HS SRGAP2B/C are necessary and sufficient to induce neotenic features of microglia structural and functional maturation in a cell-autonomous manner, and (2) induction of SRGAP2-dependent neotenic features of microglia maturation non-cell autonomously impacts synaptic development in cortical pyramidal neurons. Our results reveal that, during human brain evolution, human-specific genes SRGAP2B/C coordinated the emergence of neotenic features of synaptic development by acting as genetic modifiers of both neurons and microglia.

neuroscience↗