SEARCH · bioRxiv Science

Results for “cell biology”

Search indexed bioRxiv preprints in genomics, neuroscience, cell biology and bioinformatics. Read source abstracts and check manuscript versions; preprints are not peer reviewed.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

281 records · Page 14Linked to original sources

bioRxiv2026

Structural basis for tetraspanin-dependent surface export and adhesive function of integrin α3β1

Integrin 3{beta}1 (ITG3{beta}1) is a member of an integrin subfamily that binds to laminin proteins and promotes attachment of epithelial cells to the basement membrane. ITG3{beta}1 forms a complex with the tetraspanin CD151, and loss-of-function mutations in both ITG3 and CD151 cause epidermolysis bullosa, a severe skin blistering disease resulting from a defect in basement membrane attachment. Here, we report the cryoEM structure of an ITG3{beta}1 complex with CD151 and show that mutation of CD151 at the binding interface disrupts complex formation in cells. Strikingly, CRISPR-mediated knockout of CD151 leads to a variably penetrant ITG3{beta}1 surface export defect that is restored by re-expression of wild-type but not interface-mutated CD151. Together, these studies define the molecular basis for binding of CD151 to ITG3{beta}1, and show that CD151 promotes ITG3{beta}1 surface export, providing a biochemical explanation for the CD151 loss-of-function phenotype in epidermolysis bullosa.

biochemistry↗

bioRxiv2026

NAE1-Dependent Protein Neddylation Preserves Endothelial Identity and Vascular Integrity

Background: Endothelial dysfunction is a central driver of cardiovascular and inflammatory diseases, yet the post-translational mechanisms that preserve endothelial homeostasis remain incompletely understood. Protein neddylation, the covalent conjugation of a ubiquitin-like modifier, regulates diverse cellular processes, yet its physiological role in the vascular endothelium remains unknown. This study investigated whether protein neddylation is required to preserve endothelial identity and vascular homeostasis. Methods: We generated tamoxifen-inducible endothelial-specific Nae1 knockout mice to inhibit neddylation and combined bulk RNA sequencing, single-cell and single-nucleus transcriptomics, quantitative proteomics, biochemical analyses, and gain- and loss-of-function approaches to define the role of endothelial neddylation in vascular homeostasis and inflammatory injury. Results: Endothelial-specific Nae1 deletion caused rapid mortality associated with vascular leakage, platelet accumulation, inflammation, and multi-organ injury. Multi-omics analyses demonstrated profound loss of endothelial identity, characterized by suppression of core endothelial programs and activation of inflammatory, procoagulant, and pyroptotic pathways. Single-cell analyses revealed progressive endothelial dysfunction culminating in depletion of the endothelial population and remodeling of the vascular niche. Mechanistically, endothelial neddylation deficiency activated gasdermin D (GSDMD)- and gasdermin E (GSDME)-dependent pyroptosis, whereas dual inhibition of GSDMD and GSDME markedly attenuated inflammatory transcriptomic remodeling, vascular injury, hepatocyte death, immune cell infiltration, and platelet accumulation. Translational analyses demonstrated reduced endothelial neddylation in experimental endotoxemia and decreased expression of neddylation pathway components in human atherosclerosis and COVID-19 datasets. Conversely, restoration of endothelial neddylation partially reversed inflammatory endothelial transcriptomic reprogramming in vivo. Conclusions: NAE1-dependent protein neddylation is an essential regulator of endothelial identity and vascular integrity. Loss of endothelial neddylation promotes gasdermin-dependent pyroptosis and thrombo-inflammatory vascular injury, whereas restoration of the neddylation pathway mitigates inflammatory endothelial dysfunction. These findings identify endothelial neddylation as a fundamental mechanism maintaining vascular homeostasis and a potential therapeutic target for cardiovascular and inflammatory diseases.

pathology↗

bioRxiv2026

Cryo-EM structures reveal the mechanism of phosphatidylserine remodeling by membrane-bound glycerophospholipid O-acyltransferase 1

Lands cycle remodeling of glycerophospholipid acyl chains is crucial for cells to maintain appropriate membrane composition. Glycerophospholipids are cleaved at the glycerol sn2-position by phospholipase A. The lysophospholipids are reacylated by enzymes of the membrane-bound O-acyltransferase (MBOAT) family to incorporate specific fatty-acyl chains to adjust membrane properties. How MBOAT enzymes recognize specific acyl-CoA donors, select lysophospholipid acceptors, and release products is unclear. Phosphatidylserine (PS), a critical anionic phospholipid, controls membrane surface charge, signaling-protein recruitment, and cell-death-associated membrane recognition, and PS acyl-chain remodeling is linked to ferroptosis resistance. Here, we showed that MBOAT1 preferentially generates monounsaturated fatty acid-containing PS from lyso-PS. High-resolution cryo-electron microscopy structures of human MBOAT1 captured distinct binding poses of the fatty acyl donor, lyso-PS acceptor, and PS product. With lipidomics, enzymology and molecular dynamics simulations, these structures reveal the mechanism and pathway of MBOAT1-dependent PS remodeling.

biochemistry↗

bioRxiv2026

Meso2EM: a cross-scale CLEM workflow linking mesoscale functional imaging to targeted electron microscopy

Meso2EM is a correlative light and electron microscopy workflow that transfers neurons selected from mesoscale functional images to targeted electron microscopy. We recorded Ca{superscript 2} signals from layer 2/3 neurons across a contiguous 3 x 3 mm cortical field in awake mice and reidentified a selected neuron after fixation and tangential sectioning. Lectin-labeled vascular architecture served as a shared landmark across in vivo two-photon imaging, confocal microscopy, laboratory micro-CT of resin-embedded tissue, and block-surface scanning electron microscopy, guiding focused-ion-beam scanning electron microscopy to the target cell body. The same progressive-targeting principle also supported serial ATUM-SEM reconstruction of an in vivo-tracked dendrite and serial transmission electron microscopy of optically selected dendrites from a patch-clamp-recorded Martinotti cell. Meso2EM therefore provides a practical route for preserving target identity across large changes in scale and specimen state while restricting electron-microscopy acquisition to a selected region.

neuroscience↗

bioRxiv2026

Polymicrobial catheter biofilms sustain susceptible Enterococcus faecalis and Escherichia coli during β-lactam treatment

Broad-spectrum {beta}-lactam exposure can select for Enterococcus-dominated urinary communities in catheterized intensive-care patients, even when co-colonizing Escherichia coli remains susceptible. We investigated paired E. faecalis and E. coli isolates recovered before and after piperacillin-tazobactam (TZP) treatment using a catheter biofilm model and showed that their survival depends on mutualism and biofilm-dependent persistence. Without antibiotics, E. faecalis reduced E. coli biofilm formation yet promoted pre-attachment co-aggregation and reorganized mixed-biofilm architecture on the catheter. Despite TZP susceptibility and the absence of resistance determinants, catheter-associated biofilms and biofilm-dispersed cells survived concentrations 250- to 1000-fold above their MICs, whereas planktonic cells were eliminated. Survivors retained susceptibility but showed delayed regrowth, consistent with a transient persister-like state. In the post-treatment pair, each species sustained the other during recovery, coinciding with a nonsynonymous substitution in the enterococcal surface adhesin Esp. These findings show that antagonistic and cooperative interactions can coexist within catheter biofilms and enable susceptible polymicrobial communities to withstand {beta}-lactam treatment without {beta}-lactam resistance.

microbiology↗

bioRxiv2026

MAPT regulates autophagic-lysosomal function and phagocytosis in human microglia

Tauopathies are characterized by the accumulation and spread of pathogenic tau aggregates throughout the brain, a process that is increasingly recognized to involve not only neurons but also microglia. However, whether pathogenic MAPT directly alters microglial degradative capacity remains poorly understood. Here, using isogenic human induced pluripotent stem cell-derived microglia carrying the pathogenic MAPT IVS10+16 mutation, we identify tau as a regulator of microglial lysosomal function. MAPT IVS10+16 microglia exhibited coordinated suppression of lysosomal and autophagic pathways, reduced lysosomal protease abundance and activity, and impaired autophagosome-lysosome fusion. Mutant microglia also showed reduced uptake of extracellular tau aggregates, reduced tau accumulation in acidic compartments, and a blunted lysosomal response to proteopathic stress. Conversely, genetic loss of MAPT increased lysosomal degradative capacity and accumulation of extracellular tau aggregates within acidic compartments, supporting a cell-intrinsic role for endogenous tau in regulating microglial degradative function. Pharmacologic enhancement of the autophagy lysosome pathway in MAPT IVS10+16 microglia increased proteolytic activity and improved tau handling. Together, these findings reveal a reciprocal relationship between tau and microglial lysosome function and identify degradative capacity as a modifiable component of the microglial response to tau pathology.

neuroscience↗

bioRxiv2026

Kaposi's sarcoma-associated herpesvirus forms and maintains R-loops at origins of lytic replication

GC-rich sequences are abundant in human herpesviruses genomes. GC-rich regions can form three-stranded RNA:DNA hybrid structures called R-loops. Though these hybrid structures serve important biological roles at telomeres or during cellular DNA synthesis, unscheduled or prolonged R-loop formation causes DNA damage and genome instability. For this reason, several mechanisms exist to resolve R-loops including endoribonucleases RNaseH1 (constitutively expressed) and RNaseH2A (cell cycle-regulated) which degrade the RNA portion of the R-loop. The Kaposi's sarcoma-associated herpesvirus (KSHV) origins of lytic replication (OriLyts) contain multiple cis-acting elements that are required for viral DNA replication including the production of GC-rich and repetitive transcripts, T1.4 (OriLyt-L) and kaposin (OriLyt-R). We previously showed that R-loops form at both OriLyts and that deleting kaposin repeats or decreasing their GC-rich content prevented R-loop formation at OriLyt-R, reduced genome amplification after primary infection and caused defects in latency establishment. To define the contribution that R-loops play in KSHV replication, we overexpressed RNaseH1, reasoning that excess RNaseH1 would resolve both OriLyt R-loops. However, RNaseH1 protein levels decreased following KSHV reactivation in both iSLK and BCBL-1 cell lines. Using co-transfection, we discovered that the KSHV viral replication and transcription activator protein, RTA, mediated RNaseH1 protein decreases in a E3 ligase domain-dependent manner without impacting levels of its cognate RNA transcript. We attempted to construct an RTA-resistant yet functional version of RNaseH1 by site-directed mutagenesis of lysine residues individually or in combination, yet these constructs remain susceptible to RTA-mediated protein decreases. An amino terminally tagged RNaseH1 displayed reduced susceptibility to RTA, suggesting that RTA may target the N-terminus of RNaseH1 for ubiquitination. However, overexpression of the cell-cycle regulated endonuclease, RNaseH2, exhibited RTA resistance, suggesting RNaseH2 may be a tool that will effectively resolve R-loops during KSHV infection. KSHV is not the only herpesvirus to encode a protein that reduces RNaseH1 levels, as co-expression of RTA homologs from the related gamma-herpesviruses EBV and MHV-68 likewise decreased steady-state levels of RNaseH1 protein. We propose that RTA-mediated RNaseH1 degradation is conserved strategy to ensure R-loop persistence during gamma-herpesvirus infection, underscoring the importance of these structures.

microbiology↗

bioRxiv2026

Microglia drive demyelination via multiple sclerosis antibodies and BTK signaling

Microglia are the predominant immune cells in multiple sclerosis (MS) demyelinating lesions, where they phagocytose myelin, but whether they destroy myelin or merely scavenge its debris is unknown. Here, we explore whether pathogenic autoantibodies found in MS may induce the phagocytic destruction of myelin by microglia. Applying patient-derived, myelin-targeting antibodies to the mouse cortex, we developed an in vivo model of MS with focal demyelination that depended on epitope specificity and Fc gamma receptor and complement binding. Longitudinal monitoring of microglia-myelin interactions using in vivo two-photon microscopy revealed rapid microglial envelopment of intact myelin driving myelin loss, while single-cell RNA sequencing identified a demyelination-associated microglial signature. Parallel changes were observed in human MS lesions, where microglia enveloped intact myelin and similar genes were upregulated. Inhibition of Brutons tyrosine kinase (BTK) limited microglial transcriptional changes and prevented myelin loss following microglial envelopment. These findings directly implicate microglia in pathological myelin loss and support BTK inhibition as a therapeutic strategy to prevent demyelination by modulating microglia behavior.

neuroscience↗

bioRxiv2026

Ligand-binding/transcriptional repressor domain-deficient REV-ERBβ inhibits dendrite and spine formation of newborn adult hippocampal neurons

REV-ERB{beta} is a transcriptional repressor of nuclear receptors that regulates the circadian rhythm and plays an important role in regulation of the proliferation, differentiation, and maturation of neurons. Dysregulation of the circadian rhythm has been associated with neuropsychiatric disorders, and activation of REV-ERBs can induce anxiolytic behavior in mice. Furthermore, hippocampal neurogenesis is important in the effects of antidepressants. However, the role of REV-ERB{beta} in adult hippocampal neurogenesis in vivo at the single-cell level is not known. In this study, protein localization of REV-ERB{beta} in the subgranular zone of the hippocampal dentate gyrus (DG) was mainly shown in NeuN-positive neurons, and the effect of expressing a dominant negative form of REV-ERB{beta} lacking the C-terminal region on newborn neurons in the hippocampal DG of adult mice was examined to investigate the role of REV-ERB{beta} in neurogenesis. A retroviral vector containing the dominant negative REV-ERB{beta} or a control vector was injected into the mouse DG. At 4 weeks after injection, the morphology of dendrites and dendritic spines of newborn neurons labeled by the virus was examined. Expression of the dominant negative form of REV-ERB{beta} inhibited dendrite outgrowth and branching and decreased dendritic spine formation in newborn neurons in the adult mouse hippocampal DG. This study revealed a new role for REV-ERB&{beta} in adult hippocampal neurogenesis at the single cell level, and the results will provide insight into neurogenesis in the adult brain and its relationship with psychiatric disorders.

neuroscience↗

bioRxiv2026

Structures of pUG-fold RNA bound to DNMT1 reveal a mechanism for RNA-mediated epigenetic regulation

Many chromatin-associated proteins have been found to bind RNA as a means of epigenetic regulation. Specifically, DNA methyltransferase 1 (DNMT1), which maintains cytosine methylation at CpG dinucleotides, is inhibited by RNA at transcribed DNA loci in cells. However, the mechanisms by which RNA binds DNMT1 and inhibits its activity remain unknown. Here, we determine a series of cryogenic electron microscopy (cryo-EM) structures of human DNMT1 bound to pUG-fold RNA, a non-canonical G-quadruplex previously observed to inhibit activity, revealing two distinct RNA-binding modes. The pUG-fold RNA binds the surface of DNMT1 in its autoinhibited conformation across a positively charged surface between the methyltransferase domain and the CXXC domain, and it binds directly in the active site of an open DNMT1 conformation. RNA binding is sterically incompatible with substrate DNA engagement in both states. Our 2.5 [A] structure captures the intricate network of hydrogen bonds and electrostatic interactions between amino acids in the methyltransferase domain and the tetrad layers of pUG-fold RNA. Metadynamics molecular dynamics simulations provide an orthogonal view of the conformational landscape of DNMT1, revealing the two distinct RNA-binding modes. Furthermore, our analysis of published DNMT1 RIP-seq and eCLIP-seq data confirms that DNMT1-interacting RNAs in cells exhibit a strong propensity to form non-canonical G-quadruplex RNA structures. Collectively, our study provides the first structural basis for pUG-fold RNA recognition by a protein and illustrates how cryo-EM and AI-based methods for protein and RNA structure prediction synergize to inform the mechanism of RNA-mediated regulation of DNMT1.

biochemistry↗

bioRxiv2026

Bravais Lattice Sampling: Geometry-Guided Sparse Probing for Connected-Component Detection in 3D Discretized Spaces

We introduce Bravais Lattice Sampling (BLS), a two-phase method for detecting connected high-density regions in three-dimensional space. BLS places probe sites on a Bravais lattice scaled to the expected nearest-neighbour distance dNN of the target structures, then recovers cluster boundaries by depth-first expansion seeded only from occupied probes, replacing the exhaustive raster scan that conventional connected-component labelling uses to discover seeds. The spacing between probe sites is set from the covering radius of the lattice, which is what allows the method to state in advance the size below which a cluster may escape detection. The second phase, an expansion refinement activated only on probes that return an occupied voxel, verifies every edge, so the components returned are true connected components. BLS versatility allows for selection of different Bravais lattice unit cells to match the target structure; for amorphous, non-crystalline shapes, BLS can default to a simple face-centred cubic unit cell, where the expected minimum cluster size is the only parameter that needs to be set. The current BLS implementation has been developed as a post-processing tool for molecular dynamics trajectories, and was tested for searching water ice clusters of different morphologies. BLS returns component counts and maximum cluster sizes identical to exhaustive-labeller algorithms, with 100% recall; it runs at about 0.94 times the cost of depth-first search, and at 0.84 to 0.90 times the cost of the fastest other labeller in our benchmark set. This algorithm, although implemented by us for molecular dynamics applications, could be of interest in other domain areas where searching for high-density elements in 3D space is relevant.

bioinformatics↗

bioRxiv2026

Melanophilin, a Myosin Va Adapter Protein, Biases Track Selection of Myosin Va-and Kinesin-1-Transported Liposomes at Actin-Microtubule Intersections In Vitro

Secretory vesicle transport from the Golgi to the cell membrane involves kinesin and myosin Va motors on the vesicle surface cooperatively navigating their shared cargo through numerous actin-microtubule (MT) intersections. How the track on which the cargo exits the intersection is selected so that vesicles are delivered to their destination with spatial and temporal fidelity remains unclear. Here we hypothesized that melanophilin -- the adapter that links myosin Va to pigmented melanosomes and can bind to both actin and MTs -- acts as a phosphorylation-dependent switch to bias track preference at actin-MT intersections. To test this, we modeled melanosome transport in vitro using 350-nm liposomes with ~5 surface-bound molecules each of constitutively active myosin Va, kinesin-1, and full-length melanophilin with varying phosphorylation levels. Liposomes were then challenged with actin-MT intersections. Regardless of the track the liposomes entered the intersection on, liposomes with phosphorylated melanophilin were biased towards exiting the intersection on actin filaments while those with dephosphorylated melanophilin were biased to exit on MTs. Consistent with this, phosphorylated melanophilin showed a 2-fold preference to bind actin over MTs, and slowed liposome transport by myosin Va along actin filaments by ~40% by effectively acting as an anchor. Conversely, dephosphorylated melanophilin preferentially bound (2-fold) MTs over actin and, by acting as a tether, increased the kinesin-1 liposome transport distance on MTs. Therefore, melanophilin, based on its phosphorylation state, can bias track selection of cargo transported by kinesin-1 and myosin Va through the cell's complex cytoskeletal network with its numerous actin-MT intersections.

biophysics↗

bioRxiv2026

Comparative study of chlorophyll measurement in Physcomitrium patens moss using a conventional microscope adapted for combined 2D+1D imaging and spectral analysis

Imaging spectroscopy often requires expensive and complex equipment. Here we show a simple procedure for attaching a standard miniature fiber spectrometer to a conventional microscope, allowing easy integration of 2D imaging with 1D high-resolution spectral measurements. This combination provides much of the benefit of a full imaging spectrometer without the large equipment investment, and we provide instructions for modifying microscopes to this setup and the present measurements of living cells that demonstrate their performance. Using this setup, we compare the quantitative measurement of chlorophyll concentration in Physcomitrium patens moss using color imaging and spectral sampling.

bioengineering↗

bioRxiv2026

Comparative Transcriptional Responses of Human Blood to Neutron and Photon Irradiation

Despite the well-known health risks of neutron exposures, key gaps remain in understanding neutron-induced molecular responses and identifying reliable biodosimetric markers that distinguish neutrons from photon exposure. We provide the first genome-wide analysis of the human blood transcriptional response to an accelerator-derived fission-like spectrum of neutrons versus photons, evaluating transcriptomic relative biological effectiveness (RBE) and radiation quality-discriminating gene signatures. Whole blood from healthy donors was irradiated ex vivo with X-rays (140 kV, 0-4 Gy, n = 3) or neutrons (0.1-8 MeV, 0-1 Gy, n = 2), incubated for 6 h or 24 h, and processed for RNA sequencing from peripheral blood mononuclear cells (PBMCs). Neutrons were markedly more potent than X-rays at inducing differentially expressed genes (DEGs) at equal doses, showing a peak response 6 h post-irradiation followed by a decline. In contrast, X-rays caused a continuous increase in DEGs up to 24 h (neutrons vs. X-rays at 1 Gy: 1,449 vs. 121 DEGs at 6 h; 996 vs. 621 DEGs at 24 h). A universal p53-centered 34-gene signature, including FDXR, EDA2R, GADD45A, and ZMAT3, showed highly monotonic dose responses (Spearman correlation coefficient {approx} 1) across donors, radiation qualities, and timepoints. Additionally, difference-in-differences analysis identified radiation quality-discriminating genes only at 6 h, with transcriptional convergence observed by 24 h, suggesting a very narrow time window for biodosimetric differentiation. We identified a neutron-specific gene signature driven by cGAS-STING-NF-{kappa}B signaling (RELB, NFKB1, C3, MALAT1) and suppression of B-cell and myeloid identity genes (IGHD, TCL1A, CLEC7A, TLR2), defining a biologically coherent neutron quality index with distinct immunomodulatory effects. For the first time, we assessed neutron RBEs at the gene, pathway, and global transcriptomic levels in a human blood model, reporting a global transcriptomic neutron RBE of 1.30 (95% CI: 1.14-1.49) at 6 h and 1.21 (95% CI: 1.14-1.28) at 24 h, providing a valuable basis for biodosimetry in mixed-field exposure scenarios. Our findings advance the mechanistic understanding of neutron radiation responses and support the development of biodosimetric approaches for mixed-field exposure scenarios.

biophysics↗

bioRxiv2026

A family-wide atlas of human connexin docking compatibility

Gap junction (GJ) channels mediate direct intercellular communication by allowing the exchange of ions, metabolites, and signaling molecules between neighboring cells. Humans express 21 connexin (Cx) isoforms that can assemble into homotypic or heterotypic channels, creating a large potential interaction landscape that shapes tissue-specific communication networks. However, the rules governing which connexin isoforms can compatibly dock remain incompletely defined. Extracellular loop 2 (EL2) sequence features have been implicated in docking specificity and used to classify connexins into two canonical compatibility groups, K-N and H, but these assignments remain largely predictive. Most potential heterotypic connexin pairings have never been experimentally tested. This incomplete interaction map limits our ability to predict which connexin combinations can assemble, how isoform co-expression shapes intercellular communication, and how these relationships are altered or exploited in disease and engineered systems. Here, we used the FETCH (Flow Enabled Tracking of Connexosomes in HEK Cells) assay to evaluate docking compatibility across the complete human connexin family. To support family-wide compatibility mapping, we used literature-supported heterotypic interactions to define a data-driven FETCH score threshold for high-confidence interaction compatibility. Homotypic FETCH measurements varied substantially across the 21 connexin isoforms, with 15 producing mean scores above the empirical threshold. We then extended FETCH analysis to all 210 pairwise heterotypic isoform combinations. The resulting interaction landscape largely recapitulated expected motif-class relationships, including enrichment within the two canonical compatibility groups, but also identified neighboring-group interactions and unexpected cross-group pairings that represented clear exceptions to class-based predictions. Consistent with these findings, pairwise EL2 motif similarity was only modestly associated with threshold-based interaction classification, indicating that EL2 similarity alone was insufficient to predict compatibility outcomes. Together, these findings suggest that motif class provides a broad organizing framework for connexin compatibility, but that pairwise docking specificity also depends on yet-unresolved isoform-specific determinants that produce neighboring-group relationships and clear cross-group exceptions. Notably, Cx46, a lens Cx also associated with melanoma and breast cancers, emerged as a broadly permissive isoform capable of interacting with partners from both major compatibility groups and more than half of the connexin family. Together, these findings establish the first family-wide experimental atlas of human connexin docking compatibility, defining canonical interactions, previously unrecognized pairings, and exceptions to established compatibility rules. This atlas provides a foundation for defining the molecular determinants of connexin specificity, understanding how isoform diversity shapes intercellular communication, and designing gap junction channels with controlled docking behavior.

biochemistry↗

bioRxiv2026

Scaffold Affinity Tunes Biomolecular Condensate Function

Biomolecular condensates (BMCs) organize cellular biochemistry by concentrating selected molecules into dynamic membrane-free compartments. Yet the molecular parameters that determine not only whether condensates form, but also how they behave and what they do, remain poorly defined. Here we show that scaffold binding affinity (Kd) is a quantitative determinant of condensate phase behavior, internal dynamics and biochemical output. Using a modular SUMO-SIM system in which scaffold valency was held constant while binding affinity was systematically varied, we found that affinity governs the phase boundary, resistance to chemical perturbation, and molecular mobility of condensates in vitro and in human cells. In multicomponent mixtures, the highest-affinity scaffold dominated dense-phase composition and dynamics, revealing a hierarchical rule for condensate organization. Finally, affinity-dependent changes in condensate dynamics translated into tunable enzyme activity, establishing binding energetics as an engineerable parameter for programming condensate biochemistry.

biochemistry↗

bioRxiv2026

A Microglial Regulatory Program Linked to Neuropsychiatric Disorders

Hoxb8 is a transcription factor required for the normal function of a specialized microglial population. Loss of Hoxb8 causes compulsive overgrooming and anxiety-like behaviors in mice, with greater severity in females after sexual maturity. However, the Hoxb8-dependent transcriptional program in microglia remains poorly understood. Here, we integrated Hoxb8 chromatin occupancy, transcriptional responses, and chromatin contacts to classify genes by their spatial relationship to Hoxb8 binding. Hoxb8 occupied thousands of genomic regions, but only a subset of associated genes responded transcriptionally. Locally associated, Hoxb8-activated genes were linked to immune signaling and hormone responsiveness, whereas locally associated, Hoxb8-suppressed genes were linked to cell-cycle and genome-maintenance processes. Distally associated genes contributed to neuronal and intercellular communication and were enriched for genes associated with obsessive-compulsive disorder and anxiety. These findings reveal a functionally organized Hoxb8-dependent transcriptional program and identify potential connections between Hoxb8 activity in microglia, hormone responsiveness, intercellular communication, and neuropsychiatric disease risk.

neuroscience↗

bioRxiv2026

A nonlinear inhibition pathway underlying cortical responses to tuned holographic optogenetic perturbations

Optogenetics enables causal manipulation of cortical activity. Perturbation responses can be counterintuitive due to network interactions, making theory essential for predicting them. Existing approaches often rely on linear approximations, which fail for many biologically relevant perturbations. Here we develop a nonlinear theory of responses to holographic perturbations in cell-type-specific recurrent networks with structured connectivity. We fit a nonlinear model to mouse V1 data, which shows cotuned-ensemble suppression: perturbing spatially clustered neurons with similar preferred orientations yields markedly stronger short-range suppression than perturbing untuned ensembles. We show that cotuned-ensemble suppression arises from a feature-tuned, nonlinear inhibition pathway implicating somatostatin-positive (SST) interneurons. The theory predicts that cotuned ensembles suppress parvalbumin-positive (PV) neurons but facilitate SST neurons, and links the degree of cotuned-ensemble suppression or facilitation to the variance of the SST response. This framework identifies mechanisms by which nonlinear inhibition sculpts cortical dynamics and establishes a predictive basis for targeted optogenetic interventions.

neuroscience↗