Biology subjects

Weiner, O. D.

Publications and source records attributed to Weiner, O. D..

At least 19 recordsLinked to original sources

bioRxiv2026

From Flocks to Swarms: Rewriting the Rules of Collective Cell Migration

From flocking birds to swarming insects, collective motion enables groups to accomplish tasks beyond the capabilities of individuals. These behaviors emerge from local interactions among group members, but the interaction rules that organize collectives at the cellular scale remain poorly understood, in part because they are difficult to manipulate experimentally. Here we develop a cell-machine interface that enables us to rewrite the rules of collective migration. Cell-cell interaction rules are specified in software and implemented in living cells through real-time computer vision and closed-loop optogenetic control. Using a single engineered cell line, we program cells to self-organize into flocks, to propagate regenerative signal relays that recapitulate the interaction logic of immune-cell swarms, and to collectively navigate guidance cues that individual cells cannot. Our work shows that altering simple rules of cell-cell interaction is sufficient to generate new emergent collective capabilities. This approach provides an experimental framework for discovering the organizational principles of multicellular coordination and designing synthetic collectives with capabilities beyond those of their individual members.

synthetic biology↗

bioRxiv2026

Mechanochemical Feedback Enables Efficient Navigation in Complex Chemical Gradients

Neutrophils move through narrow pores, convoluted channels, and tight spaces in tissue to find infection sites. Their ability to sense weak chemical gradients, undergo directed motion, and solve such path-finding problems rests on internal GTPase signaling circuits that control the front protrusion and rear retraction of the cell. Here we explore several variants of known core polarity circuits, with local and long-ranged negative feedback, including inhibitor downstream of Rac, Rac-Rho antagonism, and effects of membrane tension. The resulting reaction-diffusion (RD) equations for Rac and Rho are then used to simulate protrusion-retractions along the edge of a simulated motile cell. We visualize how cells navigate through narrow tracks with sharp corners and weak chemical gradients in 2D. Our metrics for cell performance include polarity initiation, wall-collision intensity, and track completion. In this way, we expose how Rac and Rho, together with their immediate down and upstream components can fine-tune neutrophil motility through complex environments. Author SummaryWhite blood cells, attracted to sites of infection, migrate through complex tissues to find their target. Such movement requires a balance between robust polarity in one direction versus flexibility in response to spatial cues such as obstacles and sharp turns. Here we use mathematical modeling to explore known intracellular circuits that regulate front protrusion and rear retraction in directed cell migration. We test several such circuits in simulations of cells moving along zigzag tracks with sharp turns. We demonstrate that a basic cell polarity circuit, on its own, has limited success, since cells tend to get trapped in sharp corners. Known modulators of this core, which add local negative feedback, mutual front-back antagonism, and long-range feedback from membrane tension, improve cell performance. A cell with the full front-back-membrane tension regulatory circuit avoids delays due to traps and obstacle collisions, and moves swiftly through a convoluted passage to its target site.

cell biology↗

bioRxiv2026

Arachidonic acid availability controls neutrophil swarm initiation and scaling

Neutrophils are first responders of the vertebrate immune system. To efficiently converge on sites of injury and infection, neutrophils engage in a collective migration process known as swarming, in which a small number of activated cells generate amplified recruitment of hundreds to thousands of additional neutrophils. How neutrophils initiate, scale, and terminate these swarms is not well understood. Here we define key roles for the mechanosensitive phospholipase cPLA2 and its product, arachidonic acid (AA), in swarm initiation and scaling. We observe that swarm-initiating neutrophils satisfy the conditions for cPLA2 activation through two coincident inputs: yeast-contact-mediated Ca2+ influx and nuclear stretch following cell spreading along fungal hyphae and clusters. This co-requirement for both chemical and physical features of pathogens may explain how neutrophils restrict swarming to insults that require collective action. We further demonstrate that AA release is necessary and sufficient for swarming and that AA levels regulate swarm magnitude. We propose that neutrophils share AA across multiple yeastengaged cells to collectively assess infection magnitude. Because calcium influx, nuclear deformation, and cPLA2-mediated AA generation are also features of sterile-injury inflammatory responses, our findings suggest a unifying circuit for swarm regulation across injury and infection contexts.

cell biology↗

bioRxiv2025

S1P induces bleb-based T cell motility via S1PR1-dependent activation of RhoA and WNK1

In vivo, the chemokine CCL19 and its receptor CCR7 control T cell retention in lymph nodes, while the lipid chemoattractant spingosine-1-phosphate (S1P) drives T cell egress from lymphoid organs. CCL19 is known to activate actin polymerization at the leading edge of migrating cells, generating a mode of motility driven by lamellipodial protrusions. In contrast, we showed recently that S1P induces a transient lamellipodial response, followed by pressure-driven bleb-based motility. Here, we elucidate the mechanisms controlling S1P responses in naive T cells. We show that S1P signals through S1PR1, with coupling through Gai. In contrast to CCR7, which signals through Gai to induce sustained Rac1 activation, S1PR1 engagement yields only weak and transient Rac1 activation; the dominant response is sustained activation of RhoA. This pathway, together with a pathway involving phospholipase C and myosin light chain kinase, results in phosphorylation of myosin regulatory light chain (MLC) and enhanced myosin contractility. Inhibition of mTORC2 blocks MLC phosphorylation, consistent with evidence that tension sensing by mTORC2 can couple Rac1 and RhoA signaling during leukocyte migration. Surprisingly, although RhoA pathway inhibitors blocked S1P-induced MLC phosphorylation and blebbing, they failed to block S1P-dependent chemotaxis. This led to the identification of a second arm of the S1P response: WNK1-dependent phosphorylation of SPAK1 and OSXR1, proteins that regulate ion channels and water influx. Partial WNK1 inhibition, together with inhibition of myosin contractility, was sufficient to block S1P-induced blebbing and chemotaxis, indicating that S1P-driven T cell migration involves coordinate activation of myosin contractility and water influx. One sentence summaryS1P signals elicit sustained RhoA activation and water influx to drive bleb-based T cell motility.\

cell biology↗

bioRxiv2025

A mechanical origin for implantation defects in embryos from aged females

Women over 35 experience a marked reduction in fertility. The origin of these fertility defects appears to reside in the implantation capacity of the embryo itself, but the mechanistic basis of this impairment is not well-understood. Here, we identify a core mechanical defect in embryos from aged mothers that impairs the process of implantation. Using mouse models, we find that reproductive aging yields increased contractility in the extra-embryonic trophectoderm, the outer epithelial tissue responsible for mediating uterine attachment and embryo implantation. This hypercontractile state elevates tissue surface tension and viscosity in the blastocyst, culminating in defective spreading during implantation. Enhanced contractility is necessary and sufficient for this age-related defect in implantation, and early embryo mechanics can be used to predict successful implantation for embryos from both young and aged mothers. Our work represents a potential foundation for improving embryo selection in Assisted Reproductive Technologies to resolve age-related defects in female fertility.

developmental biology↗

bioRxiv2024

YAP charge patterning mediates signal integration through transcriptional co-condensates

Transcription factor dynamics are used to selectively engage gene regulatory programs. Biomolecular condensates have emerged as an attractive signaling substrate in this process, but the underlying mechanisms are not well-understood. Here, we probed the molecular basis of YAP signal integration through transcriptional condensates. Leveraging light-sheet single-molecule imaging and synthetic condensates, we demonstrate charge-mediated co-condensation of the transcriptional regulators YAP and Mediator into transcriptionally active condensates in stem cells. IDR sequence analysis and YAP protein engineering demonstrate that instead of the net charge, YAP signaling specificity is established through its negative charge patterning that interacts with Mediators positive charge blocks. The mutual enhancement of YAP/Mediator co-condensation is counteracted by negative feedback from transcription, driving an adaptive transcriptional response that is well-suited for decoding dynamic inputs. Our work reveals a molecular framework for YAP condensate formation and sheds new light on the function of YAP condensates for emergent gene regulatory behavior.

cell biology↗

bioRxiv2024

The WAVE complex forms linear arrays at negative membrane curvature to instruct lamellipodia formation.

Cells generate a wide range of actin-based membrane protrusions for various cell behaviors. These protrusions are organized by different actin nucleation promoting factors. For example, N-WASP controls finger-like filopodia, whereas the WAVE complex controls sheet-like lamellipodia. These different membrane morphologies likely reflect different patterns of nucleator self-organization. N-WASP phase separation has been successfully studied through biochemical reconstitutions, but how the WAVE complex self-organizes to instruct lamellipodia is unknown. Because WAVE complex self-organization has proven refractory to cell-free studies, we leverage in vivo biochemical approaches to investigate WAVE complex organization within its native cellular context. With single molecule tracking and molecular counting, we show that the WAVE complex forms highly regular multilayered linear arrays at the plasma membrane that are reminiscent of a microtubule-like organization. Similar to the organization of microtubule protofilaments in a curved array, membrane curvature is both necessary and sufficient for formation of these WAVE complex linear arrays, though actin polymerization is not. This dependency on negative membrane curvature could explain both the templating of lamellipodia and their emergent behaviors, including barrier avoidance. Our data uncover the key biophysical properties of mesoscale WAVE complex patterning and highlight an integral relationship between NPF self-organization and cell morphogenesis.

cell biology↗

bioRxiv2023

Rationally seeded computational protein design

Computational protein design is advancing rapidly. Here we describe efficient routes to two families of -helical-barrel proteins with central channels that bind small molecules. The designs are seeded by the sequences and structures of defined de novo oligomeric barrel-forming peptides. Adjacent helices are connected using computational loop building. For targets with antiparallel helices, short loops are sufficient. However, targets with parallel helices require longer connectors; namely, an outer layer of helix-turn-helix-turn-helix motifs that are packed onto the barrels computationally. Throughout these pipelines, residues that define open states of the barrels are maintained. This minimises sequence sampling and accelerates routes to successful designs. For each of 6 targets, just 2 - 6 synthetic genes are made for expression in E. coli. On average, 80% express to give soluble monomeric proteins that are characterized fully, including high-resolution structures for most targets that match the seed structures and design models with high accuracy.

synthetic biology↗

bioRxiv2023

Self-extinguishing relay waves enable homeostaticcontrol of human neutrophil swarming

Neutrophils exhibit self-amplified swarming to sites of injury and infection. How swarming is controlled to ensure the proper level of neutrophil recruitment is unknown. Using an ex vivo model of infection, we find that human neutrophils use active relay to generate multiple pulsatile waves of swarming signals. Unlike classic active relay systems such as action potentials, neutrophil swarming relay waves are self-extinguishing, limiting the spatial range of cell recruitment. We identify an NADPH-oxidase-based negative feedback loop that is needed for this self-extinguishing behavior. Through this circuit, neutrophils adjust the number and size of swarming waves for homeostatic levels of cell recruitment over a wide range of initial cell densities. We link a broken homeostat to neutrophil over-recruitment in the context of human chronic granulomatous disease.

cell biology↗

bioRxiv2023

Neutrophils actively swell to potentiate rapid migration

While the involvement of actin polymerization in cell migration is well-established, much less is known about the role of transmembrane water flow in cell motility. Here, we investigate the role of water influx in a prototypical migrating cell, the neutrophil, which undergoes rapid, directed movement to sites of injury and infection. Chemoattractant exposure both increases cell volume and potentiates migration, but the causal link between these processes is not known. We combine single cell volume measurements and a genome-wide CRISPR screen to identify the regulators of chemoattractant-induced neutrophil swelling, including NHE1, AE2, PI3K-gamma, and CA2. Through NHE1 inhibition in primary human neutrophils, we show that cell swelling is both necessary and sufficient for the potentiation of migration following chemoattractant stimulation. Our data demonstrate that chemoattractant-driven cell swelling complements cytoskeletal rearrangements to enhance migration speed.

cell biology↗

bioRxiv2022

Decoding of YAP levels and dynamics by pluripotency factors

YAP is a transcriptional regulator that controls pluripotency, germ layer specification, and proliferation. Different subsets of YAP target genes are engaged in each physiological setting, but how YAP selectively regulates different effectors in different contexts is not known. Here we use optogenetics to investigate how the levels and dynamics of YAP activation control its pluripotency effectors Oct4 and Nanog. We observe different thresholds for repression of Oct4 and Nanog, enabling differential control of both genes through YAP levels. Pluripotency factors also decode YAP dynamics. Oct4 preferentially responds to oscillatory YAP inputs that mimic endogenous pulsatile YAP dynamics. Using single-cell live imaging of Oct4 transcription and computational-theoretical analysis of transcriptional regulation, we demonstrate that YAP dynamics are decoded by an adaptive change sensor that modulates Oct4 transcription burst frequency. Our results reveal how the levels and timing of YAP activation enable multiplexing of information transmission for key regulators of cellular differentiation and pluripotency.

cell biology↗

bioRxiv2022

Actin-driven protrusions generate rapid long-range membrane tension propagation in cells

Membrane tension is thought to be a long-range integrator of cell physiology. This role necessitates effective tension transmission across the cell. However, the field remains strongly divided as to whether cell membranes support or resist tension propagation, in part due to a lack of adequate tools for locally manipulating membrane tension. We overcome these limitations by leveraging optogenetics to generate localized actinbased protrusions while concurrently monitoring the propagation of membrane tension using dual-trap optical tweezers. Surprisingly, actin-driven protrusions elicit rapid global membrane tension propagation with little to no attenuation, while forces applied to the cell membrane only do not. We present a simple unifying mechanical model in which mechanical forces that act on both the membrane and actin cortex drive rapid, robust membrane tension propagation. SummaryMechanical perturbations acting on both actin cortex and plasma membrane drive global membrane tension increase within seconds

cell biology↗

bioRxiv2022

From peptides to proteins: coiled-coil tetramers to single-chain 4-helix bundles

The design of completely synthetic proteins from first principles--de novo protein design--is challenging. This is because, despite recent advances in computational protein-structure prediction and design, we do not understand fully the sequence-to-structure relationships for protein folding, assembly, and stabilization. Antiparallel 4-helix bundles are amongst the most studied scaffolds for de novo protein design. We set out to re-examine this target, and to determine clear sequence-to-structure relationships, or design rules, for the structure. Our aim was to determine a common and robust sequence background for designing multiple de novo 4-helix bundles, which, in turn, could be used in chemical and synthetic biology to direct protein-protein interactions and as scaffolds for functional protein design. Our approach starts by analyzing known antiparallel 4-helix coiled-coil structures to deduce design rules. In terms of the heptad repeat, abcdefg--i.e., the sequence signature of many helical bundles--the key features that we identify are: a = Leu, d = Ile, e = Ala, g = Gln, and the use of complementary charged residues at b and c. Next, we implement these rules in the rational design of synthetic peptides to form antiparallel homo- and heterotetramers. Finally, we use the sequence of the homotetramer to derive a single-chain 4-helix-bundle protein for recombinant production in E. coli. All of the assembled designs are confirmed in aqueous solution using biophysical methods, and ultimately by determining high-resolution X-ray crystal structures. Our route from peptides to proteins provides an understanding of the role of each residue in each design.

synthetic biology↗

bioRxiv2021

Progressive enhancement of kinetic proofreading in T cell antigen discrimination from receptor activation to DAG generation

T cells use kinetic proofreading to discriminate antigens by converting small changes in antigen binding lifetime into large differences in cell activation, but where in the signaling cascade this computation is performed is unknown. Previously, we developed a light-gated immune receptor to probe the role of ligand kinetics in T cell antigen signaling. We found significant kinetic proofreading at the level of the signaling lipid diacylglycerol (DAG) but lacked the ability to determine where the multiple signaling steps required for kinetic discrimination originate in the upstream signaling cascade (Tischer and Weiner, 2019). Here we uncover where kinetic proofreading is executed by adapting our optogenetic system for robust activation of early signaling events. We find the strength of kinetic proofreading progressively increases from Zap70 recruitment to LAT clustering to downstream DAG generation. These data suggest a distributed kinetic proofreading mechanism, with proofreading steps both at the receptor and at downstream signaling events. Leveraging the ability of our system to rapidly disengage ligand binding, we measure slower reset rates for downstream signaling events. Our observations of distributed kinetic proofreading and slowed resetting of downstream steps suggest a basis of cooperativity between multiple active receptors with implications in tissue homeostasis, autoimmunity, and immunotherapy off-target effects.

immunology↗

bioRxiv2021

WASP integrates substrate topology and cell polarity to guide neutrophil migration

To control their shape and movement, cells leverage nucleation promoting factors (NPFs) to regulate when and where they polymerize actin. Here we investigate the role of the immune-specific NPF WASP during neutrophil migration. Endogenously-tagged WASP localizes to substrate-induced plasma membrane deformations. Super-resolution imaging of live cells reveals that WASP preferentially enriches to the necks of these substrate-induced membrane invaginations, a distribution that could support substrate pinching. Unlike other curvature-sensitive proteins, WASP only enriches to membrane deformations at the cell front, where it controls Arp2/3 complex recruitment and actin polymerization. Despite relatively normal migration on flat substrates, WASP depletion causes defects in topology sensing and directed migration on textured substrates. WASP therefore both responds to and reinforces cell polarity during migration. Surprisingly, front-biased WASP puncta continue to form in the absence of Cdc42. We propose that WASP integrates substrate topology with cell polarity for 3D guidance by selectively polymerizing actin around substrate-induced membrane deformations at the leading edge. A misregulation of WASP-mediated contact guidance could provide insight into the immune disorder Wiskott-Aldrich syndrome.

cell biology↗

bioRxiv2019

WAVE complex self-organization templates lamellipodial formation

How local interactions of actin regulators yield large-scale organization of cell shape and movement is not well understood. For example, why does the WAVE complex build lamellipodia, the broad sheet-like protrusions that power cell migration, whereas the homologous actin regulator N-WASP forms spiky finger-like actin networks? N-WASP is known to oligomerize into focal condensates that generate an actin finger. In contrast, the WAVE complex exhibits the linear distribution needed to generate an actin sheet. This linear organization of the WAVE complex could either arise from interactions with the actin cytoskeleton or could represent an ability of the complex to self-organize into a linear template. Using super-resolution microscopy, we find that the WAVE complex forms higher-order linear oligomers that curve into 270 nanometer-wide ring structures in the absence of actin polymer. These rings localize to the necks of membrane invaginations, which display saddle point geometries with positive curvature in one axis and negative curvature in the orthogonal axis. To investigate the molecular mechanism of saddle curvature enrichment, we show that the WAVE complex and IRSp53, a membrane curvature-sensitive protein, collaborate to recognize saddle curvature that IRSp53 cannot sense alone. This saddle preference for the WAVE complex could explain emergent cell behaviors, such as expanding and self-straightening lamellipodia as well as the ability of endothelial cells to recognize and seal transcellular holes. Our work highlights how partnering protein interactions enable complex shape sensing and how feedback between cell shape and actin regulators yields self-organized cell morphogenesis.

cell biology↗

bioRxiv2018

Cell-extrinsic mechanical forces restore neutrophil polarization in the absence of branched actin assembly

Migratory cells use distinct motility modes to navigate different microenvironments, but it is unclear whether these modes rely on the same core set of polarity components. To investigate this, we disrupted Arp2/3 and WAVE complex, which assemble branched actin networks that are essential for neutrophil polarity and motility in standard adherent conditions. Surprisingly, confinement rescues polarity and movement of neutrophils lacking these components, revealing a processive bleb-based protrusion program that is mechanistically distinct from the branched actin-based protrusion program but shares some of the same core components and underlying molecular logic. We further find that the restriction of protrusion growth to one site does not always respond to membrane tension directly, as previously thought, but may rely on closely linked properties such as local membrane curvature. Our work reveals a hidden circuit for neutrophil polarity and indicates that cells have distinct molecular mechanisms for polarization that dominate in different microenvironments.

cell biology↗

bioRxiv2018

Light-based tuning of ligand half-life supports kinetic proofreading model of T cell activation

T cells are thought to discriminate stimulatory versus non-stimulatory ligands by converting small changes in ligand binding half-life to large changes in cell activation. Such a kinetic proofreading model has been difficult to test directly, as existing methods of altering ligand binding half-life also change other potentially important biophysical parameters, most notably the stability of the receptor-ligand interaction under load. Here we develop an optogenetic approach to specifically tune the binding half-life of a light-responsive ligand to a chimeric antigen receptor without changing other binding parameters. By simultaneously manipulating binding half-life while controlling for receptor occupancy, we find that signaling is strongly gated by ligand binding half-life. Our results provide direct evidence of kinetic proofreading in ligand discrimination by T cells.\n\nOne Sentence SummaryDirect control of ligand binding half-life with light shows that lifetime, not occupancy, dominates T cell activation.

immunology↗