Biology subjects

Gabriele, S.

Publications and source records attributed to Gabriele, S..

11 recordsLinked to original sources

bioRxiv2026

CurvoChip: a programmable dynamic curvature-on-chip platform for epithelial mechanobiology

Epithelial tissues continuously remodel their curvature during morphogenesis, homeostasis, regeneration, and disease, yet experimental access to time-varying curvature remains limited. Here, we introduce CurvoChip, a pneumatically actuated microsystem that reversibly deforms confluent epithelial monolayers cultured on a 20-m elastic membrane into concave or convex geometries. The device operates either in a standard incubator or on a microscope stage and provides programmable control over pressure amplitude, direction, and cycling. Analytical scaling, finite-element simulations, and confocal profilometry establish predictable membrane deformation across the operating range, whereas cycling between -400 and +400 mbar for 120 cycles produces stable deflection without detectable drift or residual deformation. We further implement a three-dimensional surface-reconstruction and segmentation workflow to quantify cell and nuclear morphology on curved monolayers. Acute curvature induction produces a marked polarity-dependent response: convex deformation causes greater cell spreading and epithelial thinning than concave deformation, while nuclear projected area, thickness, and volume change in a direction- and position-dependent manner. These results show that epithelial architecture is sensitive not only to curvature magnitude but also to its orientation relative to the apico-basal axis. CurvoChip therefore provides an accessible platform for dissecting how epithelial tissues integrate dynamic geometric cues.

biophysics↗

bioRxiv2026

Geometric confinement regulates ERK signaling dynamics and collective migration

Collective cell migration is a fundamental process in morphogenesis, tissue repair, cancer invasion, and frequently occurs under geometric confinement in vivo. However, how confinement interfaces with signaling pathways that coordinate collective motion remains poorly understood. Here, we confine migrating epithelial monolayers within adhesive microstripes of defined width and observe a progressive slow-down of collective migration with increasing spatial confinement. Combining biophysical modeling, live imaging of ERK activity, and pharmacological perturbations, we show that confinement increases tissue crowding while reducing cell and nuclear projected areas, thereby shifting epithelial tissues toward a mechanically compressed state associated with dampened ERK waves. Across conditions, migration speed scales with ERK signaling dynamics, which correlates with EGFR signaling as well as cell and nuclear projected areas, together serving as quantitative proxies for the confinement-imposed mechanical state. Pharmacological inhibition of ROCK restores cell spreading, ERK signaling, and migration under strong confinement, demonstrating that this state is reversible and governed by actomyosin contractility. Together, our results identify geometric confinement as a physical regulator of a contractility-dependent mechanochemical state that controls ERK signaling and collective migration in epithelial tissues.

biophysics↗

bioRxiv2026

Microtubule detyrosination enhances matrix remodeling and force transmission during endothelial sprouting

Angiogenic sprouting relies on the coordinated regulation of endothelial migration, force generation, and extracellular matrix (ECM) remodeling. While microtubules are known to regulate cell polarity and migration, how tubulin post-translational modifications reshape microtubule behavior and impact matrix-dependent migration programs remain unclear. Here, using sprouting angiogenesis as an integrative physiological context, we combine live-cell imaging, three-dimensional (3D) sprouting and microfluidic invasion assays, and 3D traction force microscopy to dissect the role of tubulin detyrosination and acetylation. We show that microtubule detyrosination, in contrast to acetylation, promotes directional persistence, sprout elongation and collective endothelial invasion. Detyrosinated microtubules remain dynamic and display more persistent growth, supporting sustained directional migration. Strikingly, microtubule detyrosination also enhances ECM remodeling, leading to increased matrix degradation and augmented traction force transmission. Functional inhibition experiments reveal that matrix degradation, rather than actomyosin contractility, is required for both elevated forces and enhanced sprouting. Together, these findings identify microtubule detyrosination as a key regulator linking cytoskeletal dynamics, cell migration and matrix remodeling during angiogenesis.

cell biology↗

bioRxiv2025

Carotenoid-based immune response in sea cucumbers relies on newly identified coelomocytes -- the carotenocytes

Sea cucumbers (Holothuroidea, Echinodermata) are marine deuterostomes possessing a complex innate immune system composed of a wide diversity of immune cells--coelomocytes, making them compelling models for exploring the evolution of immunity. This study investigates the functional specialisation of coelomocytes within the two main echinoderm body fluids, namely the perivisceral fluid (PF) from the perivisceral cavity and the hydrovascular fluid (HF) from the hydrovascular-- ambulacral system. Given their specific distribution restricted to the HF, hemocyte-like cells (HELs) are particularly investigated. In echinoderms, hemocytes have been described as reddish cells containing haemoglobin and thus presenting a function in oxygen transport. Using an integrative approach combining cell morphological analyses, pigment profiling and multi-omics technologies, we demonstrate, in the sea cucumber Holothuria forskali, that HELs harbour exceptionally high concentrations of carotenoids, primarily canthaxanthin and astaxanthin--potent antioxidant molecules responsible for their pigmentation. Transcriptomics and proteomics analyses reveal that HELs express candidate genes involved in the carotenoid metabolism pathway as well as catalase, an antioxidant enzyme. Additionally, spectral flow cytometry assays reveal that HELs do not produce reactive oxygen species in contrast to most coelomocyte types, reinforcing the hypothesis of their antioxidant function. HELs also contribute to the formation of large red bodies (i.e., coelomocyte aggregates) and increase in concentration following lipopolysaccharide injections, indicating an active role in immune defence. Given these results, we hypothesise that these cells act after the culmination of the immune response, forming an antioxidant shell around the cellular aggregates to mitigate oxidative stress from reactive oxygen species (ROS) produced within the aggregate while encapsulating pathogens, thus protecting the host tissues. The discovery of carotenoid-carrying coelomocytes constitutes the first report of pigmented coelomocytes in sea cucumbers (except respiratory pigments), challenging the long-standing assumption that these cells contain haemoglobin. Therefore, we propose renaming hemocytes into carotenocytes, at least in this species. However, we think that this newly described coelomocyte type has been wrongly identified as haemoglobin-containing cells in many previous studies and could be present in many other holothuroid species. Our findings thus establish a new paradigm in the study of coelomocytes in echinoderms as well as the function of the hydrovascular system, unique to this phylum.

evolutionary biology↗

bioRxiv2025

Tube feet dynamics drive adaptation in sea star locomotion

Sea stars use hundreds of tube feet on their oral surface to crawl, climb, and navigate complex environments--all without the coordination of a central brain. While the morphology of tube feet and their role as muscular hydrostats are well described, the dynamics underlying their locomotion remain poorly understood. To investigate these dynamics, we employed an optical imaging method based on frustrated total internal reflection to visualize and quantify tube foot adhesion in real time across individuals of Asterias rubens spanning a wide size range. Our results reveal an inverse relationship between crawling speed and the duration of tube foot contact with the substrate. This suggests that sea stars regulate locomotion by modulating foot-substrate interaction time in response to body load. To test this, we conducted perturbation experiments using 3D-printed backpacks that increased body mass by 25% and 50%, along with numerical simulations based on a mechanistic model incorporating decentralized feedback control of the tube feet. The added load significantly increased adhesion time, supporting the role of a load-dependent mechanical adaptation. We further investigated inverted locomotion, both experimentally and through simulation, and found that tube feet adjust their contact behavior when the animal is oriented upside down relative to gravity. Together, our findings demonstrate that sea stars adapt their locomotion to changing mechanical demands by modulating tube foot-substrate interactions, revealing a robust, decentralized strategy for navigating diverse and challenging terrains.

biophysics↗

bioRxiv2024

HYDRA: HYdrogel Dispensing with Robotic Automation for high throughput drug testing

Traditional plastic- and glass-based cell culture platforms lack physiological relevance which limits their predictive power in drug development. Organoids and organs-on-chip offer biomimicry in late preclinical stages but lack scalability for high-throughput screening (HTS) in earlier stages. In fact, even introducing the simplest critical biomimetic cue, thin hydrogel layers, into the small wells of HTS plates causes the formation of curved menisci that disrupt cell seeding and imaging. We introduce HYDRA (HYDrogels by Robotic liquid handling Automation), an automated method that enables consistent hydrogel fabrication in HTS plates. We used liquid handling robots to dispense hydrogel precursor solutions and avoid contact with the sidewalls to prevent meniscus formation. We used gelatin for its mild surfactant properties, which allow pinning of the droplets contact line, promoting uniform spread. Finally, we re-aspirated the excess liquid, leaving behind a hydrogel layer with controlled stiffness and thickness. We show compatibility with standard 96- and 384-well plates and integration with existing automated workflows, including quality control. We validated HYDRA in dose-response assays using anti-cancer drugs, genetically engineered epithelial cells, phase holography, and fluorescence microscopy. We believe that HYDRA provides a scalable, biomimetic, and therefore more predictive alternative for early- stage screening and in vitro drug testing.

bioengineering↗

bioRxiv2024

The actin cortex acts as a mechanical memory of morphology in confined migrating cells

Cell migration in narrow microenvironments is a hallmark of numerous physiological processes, involving successive cycles of confinement and release that drive significant morphological changes. However, it remains unclear whether migrating cells can retain a memory of their past morphological states, which could potentially enhance their navigation through confined spaces. By combining cell migration assays on standardized microsystems with biophysical modeling and biochemical perturbations, we demonstrate that local geometry governs these morphological switches, thereby facilitating cell passage through long and narrow gaps. We uncovered a long-term memory of past confinement events in migrating cells, with morphological states correlated across transitions through actin cortex remodeling. These findings suggest that mechanical memory in migrating cells plays an active role in their migratory potential in confined environments.

biophysics↗

bioRxiv2024

Chiral mismatch in collagen-mimetic peptides modulates cell migration through integrin-mediated molecular recognition

Chirality influences essential biological processes such as molecular recognition and self- organization, impacting cell proliferation and differentiation mediated by interactions with the extracellular matrix (ECM). Despite extensive research on cell migration, the role of chirality on matrix-cell interactions has been largely overlooked. To explore this aspect, we engineered culture surfaces coated with natural collagen I or collagen-mimetic peptides (CMPs) with opposite chirality, i.e. with either L- or D-amino acids in their sequences. Here we show that D-surfaces impede epithelial keratocyte spreading, making cells more rounded, less adhesive, and slower. Further investigation through integrin inhibition assays and molecular dynamics simulations revealed that a chiral mismatch destabilizes the triple helix of heterochiral CMPs at the L/D junction. This study underscores the profound impact of ECM chirality on cellular behavior, providing new insights into the relationship between matrix (supra)molecular chirality, integrin-mediated molecular recognition, and cell migration dynamics.

biophysics↗

bioRxiv2024

Matrix viscoelasticity controls epithelial cell mechanobiology through dimensionality

In recent years, matrix viscoelasticity has emerged as a potent regulator of fundamental cellular processes and has been implicated in promoting cancer progression. Alongside viscoelasticity, additional ECM cues have been shown to influence migration decision-making of cancer cells, and spatial confinement is now considered as a potential regulator of metastasis. However, our understanding of these complex processes predominantly relies on purely elastic hydrogels, and the exact relationship between matrix viscoelasticity and spatial confinement in driving epithelial cell mechanotransduction and migration during cancer progression remains unclear. Here, we systematically investigated the interplay between matrix stiffness, viscoelasticity and spatial confinement by engineering soft ([~]0.3 kPa) and stiff ([~]3 kPa) polyacrylamide hydrogels with varying degrees of viscous dissipation, mirroring the mechanical properties of healthy and tumoral conditions in breast tissue. We observed that viscoelasticity modulates cell spreading, focal adhesions and YAP nuclear import in opposite directions on soft and stiff substrates. Strikingly, viscoelasticity enhances migration speed and persistence on soft substrates, while impeding them on stiff substrates via actin retrograde flow regulation. Combining soft micropatterning with viscoelastic hydrogels, we also show that spatial confinement restricts cell migration on soft matrices regardless of matrix viscoelasticity and promotes migration on stiff matrices in a viscoelasticity-dependent fashion. Our findings establish substrate viscoelasticity as a key regulator of epithelial cell functions and unravel the role of the matrix dimensionality in this process. SignificanceWhile matrix elasticity has received significant attention, recent findings underscore the importance of its natural dissipative properties and spatial confinement in regulating cellular processes and tumour invasiveness. However, the intricate interplay between viscoelasticity and spatial confinement in orchestrating epithelial cell behaviour during cancer progression remains elusive. Using micropatterned viscoelastic hydrogels to replicate the mechanical properties encountered during breast tumour progression, we unveil that viscoelasticity modulates cell behaviour and mechanotransduction signals differently on soft and stiff substrates. Increased viscoelasticity enhances migration speed and persistence on soft substrates while impeding them on stiff substrates via actin retrograde flow regulation. Furthermore, spatial confinement restricts cell migration on soft matrices regardless of viscoelasticity, while promoting migration on stiff matrices in a viscoelasticity-dependent manner.

biophysics↗

bioRxiv2020

Role of TNF-α among inflammatory molecules secreted by injured astrocytes in the modulation of in vitro neuronal networks

Traumatic brain injury (TBI) remains one of the leading causes of mortality and morbidity worldwide. Despite its high prevalence and extensive efforts to develop neuroprotective therapies, effective treatments for TBI are still limited. Among important neuronal damages, TBI induces structural and functional alterations of astrocytes, the most abundant cell type in the brain. Injured astrocytes respond in diverse mechanisms that result in reactive astrogliosis and are involved in the physiopathological mechanisms of TBI in an extensive and sophisticated manner. The establishment of effective neuroprotective treatments for TBI requires to better understand the complex biochemical interactions between activated astrocytes and neurons that contribute to the secondary injury. To address this challenge, we studied in vitro the role of mechanically injured astrocytes on the growth and synaptic connections of cortical neuronal networks of controlled architectures grown on well-defined protein micropatterns. Astrocytes were cultivated on elastic membranes and mechanically activated by stretching cycles. The culture media of healthy or activated astrocytes was then introduced on neuronal networks. We analyzed the neuronal viability, the neurite growth and the synaptic density of neuronal networks to understand the role of the inflammatory molecules secreted by mechanically activated astrocytes. Furthermore, we cultivated neuronal networks during 13 days with different doses of TNF- in order to decipher its individual contribution among the other cytokines. Here we show that the ratio of tubulin to synapsin area was significantly higher in neuronal networks treated with either 4 or 2 doses of TNF-, suggesting that TNF- can promote the tubulin polymerization process. Assuming that TNF- can bind to either TNFR1 or TNFR2 receptors, which lead respectively to the cell survival or the cell apoptosis, we studied the modulation of the both TNF- receptors in response to the medium of mechanically activated astrocytes and different doses of TNF-. Our findings indicate that the amount of both receptors increases with the maturation of the network. In addition, we observed a significant modulation of the amount of TNFR1 and TNFR2 in response to the media of injured astrocytes that leads to a large imbalance between both receptors, suggesting an important role for TNF-signaling in the physiopathological mechanisms of TBI.

biophysics↗

bioRxiv2020

Large-scale curvature sensing by epithelial monolayers depends on active cell mechanics and nuclear mechanoadaptation

While many tissues fold in vivo in a highly reproducible and robust way, epithelial folds remain difficult to reproduce in vitro, so that the effects and underlying mechanisms of local curvature on the epithelial tissue remains unclear. Here, we photoreticulated polyacrylamide hydrogels though an optical photomask to create corrugated hydrogels with isotropic wavy patterns, allowed us to show that concave and convex curvatures affect cellular and nuclear shape. By culturing MDCK epithelial cells at confluency on corrugated hydrogels, we showed that the substrate curvature leads to thicker epithelial zones in the valleys and thinner ones on the crest, as well as corresponding density, which can be generically explained by a simple 2D vertex model, leading us to hypothesize that curvature sensing could arise from resulting density/thickness changes. Additionally, positive and negative local curvatures lead to significant modulations of the nuclear morphology and positioning, which can also be well-explained by an extension of vertex models taking into account membrane-nucleus interactions, where thickness/density modulation generically translate into the corresponding changes in nuclear aspect ratio and position, as seen in the data. Consequently, we find that the spatial distribution of Yes associated proteins (YAP), the main transcriptional effector of the Hippo signaling pathway, is modulated in folded epithelial tissues according to the resulting thickness modulation, an effect that disappears at high cell density. Finally, we showed that these deformations are also associated with changes of A-type and B-type lamin expression, significant chromatin condensation and to lower cell proliferation rate. These findings show that active cell mechanics and nuclear mechanoadaptation are key players of the mechanistic regulation of epithelial monolayers to substrate curvature, with potential application for a number of in vivo situations.Competing Interest StatementThe authors have declared no competing interest.View Full Text

biophysics↗