Biology subjects

Hutson, M. S.

Publications and source records attributed to Hutson, M. S..

10 recordsLinked to original sources

bioRxiv2026

Cell fusion after wounding requires plasma membrane damage and endocytosis

Tissue wounds comprise both dead and damaged cells. In epithelial wounds, repair is accomplished by cells at the wound edges, which are themselves often damaged. In the Drosophila pupal notum, wound-adjacent epithelial cells with plasma membrane damage often fuse to form syncytia; when plasma membrane damage is prevented, syncytia do not form. Damaged cells share cytoplasm as soon as milliseconds after wounding, and fusion pores connecting cell membranes form minutes later. A genetic screen reveals that wound-induced fusion requires endocytosis machinery, and dynamin localization indicates that endocytosis preferentially targets plasma membrane removed during fusion. Endocytosis promotes cell fusion by specifically promoting fusion pore expansion, indicated by quantitative analysis of cytoplasmic sharing between cells over time. Without endocytosis-mediated cell fusion, wound healing is slowed. Together, our results support a model of damage-induced cell fusion in which plasma membrane damage initiates fusion pores and endocytosis expands fusion pores, resulting in cellular fusion as an integration of single cell damage with tissue repair.

cell biology↗

bioRxiv2025

Quantifying and modeling loss of steroid hormones in PDMS-based devices

Many polydimethylsiloxane (PDMS)-based devices, e.g., organ-on-chip or microphysiological systems, have been developed to investigate biological processes at a miniaturized scale. These devices typically culture cells under microfluidic perfusion to dynamically dose cells with chemicals of interest; however, PDMS is known to interact with hydrophobic compounds and can strongly limit such compounds in-device bioavailability. Here, we quantify chemical-PDMS interactions for three commonly used steroid hormones: aldosterone, estradiol, and progesterone. We find that aldosterone does not detectably interact with PDMS; estradiol interacts modestly; and progesterone interacts strongly. Based on these measured interactions, we computationally model dynamic dosing protocols based on pulsed/bolus delivery and circadian control. We show that interactions with PDMS can strongly disrupt these dynamic dosing protocols in a chemical-specific and flow-rate-dependent manner. These results have critical implications for the use of steroid hormones in PDMS-based devices.

bioengineering↗

bioRxiv2024

Toxicokinetics for organ-on-chip devices

Organ-on-chip (OOC) devices are an emerging New Approach Method in both pharmacology and toxicology. Such devices use heterotypic combinations of human cells in a micro-fabricated device to mimic in vivo conditions and better predict organ-specific toxicological responses in humans. One drawback of these devices is that they are typically made from polydimethylsiloxane (PDMS), a polymer known to interact with hydrophobic chemicals. Due to this interaction, the actual dose experienced by cells inside OOC devices can differ strongly from the nominal dose. To account for these effects, we have developed a comprehensive toxicokinetic approach to measure and model chemical-PDMS interactions, including partitioning into and diffusion through PDMS. We use these methods to characterize PDMS interactions for ten chemicals, ranging from fluorescent dyes to persistent organic pollutants to organophosphate pesticides. We further show that these methods return physical interaction parameters that can be used to accurately predict time-dependent doses under continuous-flow conditions, as would be present in an OOC device. These results demonstrate the validity of the methods and model across geometries and flow rates.

bioengineering↗

bioRxiv2023

Piezo initiates transient production of collagen IV to repair damaged basement membranes

Basement membranes are extracellular matrix sheets separating tissue layers and providing mechanical support, and Collagen IV (Col4) is their most abundant protein. Although basement membranes are repaired after damage, little is known about repair, including whether and how damage is detected, what cells repair the damage, and how repair is controlled to avoid fibrosis. Using the intestinal basement membrane of adult Drosophila as a model, we show that after basement membrane damage, there is a sharp increase in enteroblasts transiently expressing Col4, or "matrix mender" cells. Enteroblast-derived Col4 is specifically required for matrix repair. The increase in matrix mender cells requires the mechanosensitive ion channel Piezo, expressed in intestinal stem cells. Matrix menders are induced by the loss of matrix stiffness, as specifically inhibiting Col4 crosslinking is sufficient for Piezo-dependent induction of matrix mender cells. Our data suggest that epithelial stem cells control basement membrane integrity by monitoring stiffness.

cell biology↗

bioRxiv2023

Wound-Induced Syncytia Outpace Mononucleate Neighbors during Drosophila Wound Repair

In response to injury, cells proliferate, migrate and invade to replace missing cells and close wounds. However, the role of other wound-induced cell behaviors is not understood, including the formation of syncytia (multinucleated cells). Here, we use in vivo live imaging to analyze wound-induced syncytia in mitotically competent Drosophila pupae. We find that almost half the epithelial cells near a wound fuse to form large syncytia. When the autophagy gene Atg1 is knocked down, fewer syncytia form, and wounds close more slowly. Further, a computational model of tissue fluidity indicates that cell fusion speeds wound closure time by about one third. Syncytia use several routes to speed wound repair: they outpace diploid cells at the wound margin to lead the initial resealing of the wound; they reduce the need for intercalation as the tissue reshapes during closure; and they pool resources of their component cells to concentrate them toward the wound margin. In addition to wound healing, these properties of syncytia are likely to contribute to their roles in development and pathology.

cell biology↗

bioRxiv2023

After wounding, a G-protein coupled receptor restores tension to epithelial cells in a dynamic inward-traveling wave

The maintenance of epithelial barrier function involves cellular tension, with cells pulling on their neighbors to maintain epithelial integrity. Wounding interrupts cellular tension, which may serve as an early signal to initiate epithelial repair. To characterize how wounds alter cellular tension, we used a laser-recoil assay to map cortical tension around wounds in the epithelial monolayer of the Drosophila pupal notum. Within a minute of wounding, there was widespread loss of cortical tension along both radial and tangential directions. This tension loss was similar to levels observed with Rok inactivation. Tension was subsequently restored around the wound, first in distal cells and then in proximal cells, reaching the wound margin about 10 minutes after wounding. Restoring tension required the GPCR Mthl10 and the IP3 receptor, indicating the importance of this calcium signaling pathway known to be activated by cellular damage. Tension restoration correlated with an inward-moving contractile wave that has been previously reported; however, the contractile wave itself was not affected by Mthl10 knockdown. These results indicate that cells may transiently increase tension and contract in the absence of Mthl10 signaling, but that pathway is critical for fully resetting baseline epithelial tension after it is disrupted by wounding.

biophysics↗

bioRxiv2022

A mathematical model of calcium signals around laser-induced epithelial wounds

Cells around epithelial wounds must first become aware of the wounds presence in order to initiate the wound healing process. An initial response to an epithelial wound is an increase in cytosolic calcium followed by complex calcium signaling events. While these calcium signals are driven by both physical and chemical wound responses, cells around the wound will all be equipped with the same cellular components to produce and interact with the calcium signals. Here, we have developed a mathematical model in the context of laser-ablation of the Drosophila pupal notum that integrates tissue-level damage models with a cellular calcium signaling toolkit. The model replicates experiments in the contexts of control wounds as well as knockdowns of specific cellular components, but it also provides new insights that are not easily accessible experimentally. The model suggests that cell-cell variability is necessary to produce calcium signaling events observed in experiments, it quantifies calcium concentrations during wound-induced signaling events, and it shows that intercellular transfer of the molecule IP3 is required to coordinate calcium signals across distal cells around the wound. The mathematical model developed here serves as a framework for quantitative studies in both wound signaling and calcium signaling in the Drosophila system.

biophysics↗

bioRxiv2021

Zones of Cellular Damage Around Pulsed-Laser Wounds

After a tissue is wounded, cells surrounding the wound adopt distinct wound-healing behaviors to repair the tissue. Considerable effort has been spent on understanding the signaling pathways that regulate immune and tissue-resident cells as they respond to wounds, but these signals must ultimately originate from the physical damage inflicted by the wound. Tissue wounds comprise several types of cellular damage, and recent work indicates that different types of cellular damage initiate different types of signaling. Hence to understand wound signaling, it is important to identify and localize the types of wound-induced cellular damage. Laser ablation is widely used by researchers to create reproducible, aseptic wounds in a tissue that can be live-imaged. Because laser wounding involves a combination of photochemical, photothermal and photomechanical mechanisms, each with distinct spatial dependencies, cells around a pulsed-laser wound will experience a gradient of damage. Here we exploit this gradient to create a map of wound-induced cellular damage. Using genetically-encoded fluorescent proteins, we monitor damaged cellular and sub-cellular components of epithelial cells in living Drosophila pupae in the seconds to minutes following wounding. We hypothesized that the regions of damage would be predictably arrayed around wounds of varying sizes, and subsequent analysis found that all damage radii are linearly related over a 3-fold range of wound size. Thus, around laser wounds, the distinct regions of damage can be estimated after measuring any one. This report identifies several different types of cellular damage within a wounded epithelial tissue in a living animal. By quantitatively mapping the size and placement of these different types of damage, we set the foundation for tracing wound-induced signaling back to the damage that initiates it.

cell biology↗

bioRxiv2020

A protease-initiated model of wound detection

Wounds trigger surrounding cells to initiate repair, but it is unclear how cells detect wounds. The first known wound response of epithelial cells is a dramatic increase in cytosolic calcium, which occurs within seconds, but it is not known what initiates this calcium response. Specifically, is there an instructive signal detected by cells surrounding wounds? Here we identify a signal transduction pathway in epithelial cells initiated by the G-protein coupled receptor Methuselah-like 10 (Mthl10) activated around wounds by its cytokine ligands, Growth-blocking peptides (Gbps). Gbps are present in unwounded tissue in latent form, requiring proteolytic activation for signaling. Multiple protease families can activate Gbps, suggesting it acts as a detector to signal the presence of several proteases. We present experimental and computational evidence that proteases released during cell lysis serve as the instructive signal from wounds, liberating Gbp ligands to diffuse to the Mthl10 receptors on epithelial cells and activate downstream release of calcium. Thus, the presence of a nearby wound is signaled by the activation of a Gbp protease detector, sensitive to multiple proteases released after cellular damage.

cell biology↗

bioRxiv2018

Elongated cells drive morphogenesis in a surface-wrapped finite element model of germband retraction

During Drosophila embryogenesis, the germband first extends to curl around the posterior end of the embryo, and then retracts back; however, retraction is not simply the reversal of extension. At a tissue level, extension is coincident with ventral furrow formation, and at a cellular level, extension occurs via convergent cell neighbor exchanges in the germband while retraction involves only changes in cell shape. To understand how cell shapes, tissue organization and cellular forces drive germband retraction, we investigate this process using a whole-embryo, surface-wrapped cellular finite element model. This model represents two key epithelial tissues - amnioserosa and germband - as adjacent sheets of 2D cellular finite elements that are wrapped around an ellipsoidal 3D approximation of an embryo. The model reproduces the detailed kinematics of in vivo retraction by fitting just one free model parameter, the tension along germband cell interfaces; all other cellular forces are constrained to follow ratios inferred from experimental observations. With no additional parameter adjustments, the model also reproduces failures of retraction when amnioserosa cells are removed to mimic U-shaped mutants or laser-microsurgery experiments. Surprisingly, retraction in the model is robust to changes in cellular force values, but is critically dependent on starting from a configuration with highly elongated amnioserosa cells. Their extreme cellular elongation is established during the prior process of germband extension and is then used to drive retraction. The amnioserosa is the one tissue whose cellular morphogenesis is reversed in germband extension and retraction - serving as a store of morphological information that coordinates the forces needed to retract the germband back to its pre-extension position and shape. In this case, and perhaps more generally, cellular force strengths are less important than the carefully established cell shapes that direct them.

biophysics↗