Biology subjects

Cartagena-Rivera, A. X.

Publications and source records attributed to Cartagena-Rivera, A. X..

10 recordsLinked to original sources

bioRxiv2026

Collagen V Presented at the Cell-Substrate Interface Mimics Substrate Stiffening to Enhance Fibroblast Traction, Adhesion Turnover, and Persistent Migration

Collagen type V (Col-V) is a minor fibrillar collagen that regulates collagen fibril assembly, and its haploinsufficiency causes classical Ehlers-Danlos syndrome, in which wound healing is delayed. Whether Col-V also changes how fibroblasts adhere to, pull on, and migrate across a collagen-presenting surface has not been tested directly. Here, we covalently coupled Col-I or Col-V to soft (2.7 kPa) silicone substrates and quantified the mechanical response of NIH/3T3 fibroblasts. On Col-V, cells generated about 1.5-fold higher traction, spread more, and formed smaller focal adhesions that each carried more force. Adhesions on Col-V assembled and disassembled faster. Single fibroblasts on Col-V migrated more slowly but more persistently, and fibroblast monolayers closed a 500 micrometer gap faster. Raising substrate stiffness to 13 kPa reproduced this phenotype on Col-I, including higher traction, larger spread area, and smaller focal adhesions, indicating that Col-V presentation produces an adhesion state that otherwise requires a stiffer substrate. In separate reconstituted collagen hydrogels, co-assembly with 10 to 20% Col-V yielded thinner, straighter fibrils, and 20% Col-V increased the indentation modulus of the gel. These results identify the collagen type presented at the cell-material interface as a design parameter that can partly substitute for bulk stiffness in controlling fibroblast traction and migration, and they suggest Col-V as a tunable component of collagen-based biomaterials.

bioengineering↗

bioRxiv2026

Dynein-microtubule forces drive nucleokinesis and transmigration in T cells

Beyond the mechanical capacity of canonical actomyosin-driven amoeboid motility in permissive extracellular environments, the nucleus becomes the principal barrier to T cell migration in confining tissues. We establish the dynein-microtubule (MT) force-transmission axis as an essential mechanism for nuclear translocation during confined T cell migration and transmigration. We argue that dynein acts both as a motor and as an F-actin-anchored force-transmission element (fulcrum), sliding MTs and the MT-coupled nucleus along the cell cortex to drive nucleokinesis and productive cell displacement. Dynein is the primary driver of nucleokinesis: its inhibition arrests nucleus movement independently of myosin II activity, while F-actin dynamics remain spatiotemporally decoupled from nuclear oscillations. During transmigration, dynein and actomyosin act cooperatively and non-redundantly, and only combined inhibition abolishes nuclear passage. Computational modeling demonstrates that dynein-mediated pulling, together with volume exclusion imposed by the nucleus, is sufficient to generate self-organized nuclear oscillations. Dynein inhibition in zebrafish Langerhans cells impairs protrusion dynamics in situ, identifying the dynein-MT axis as an evolutionarily conserved mechanobiological program. Collectively, these findings identify the dynein-MT mechanical unit as a potential target for engineering T cells with enhanced solid-tumor infiltration.

cell biology↗

bioRxiv2025

Immune Cell Migration Models Synergize Nuclear Piston, Uropod, and Microenvironment into Hydraulic Cell Engine

The nucleus and uropod are the largest and most mechanically distinct structures in migrating amoeboid lymphocytes, including NK, B, and T cells. The biophysical properties of these structures may shape the ability of immune cells to navigate dense tissue microenvironments during immune surveillance. Using bead-spring and agent-based cell models, we explore the biomechanical contributions of the nucleus, uropod, septin-templated cortical rings, actomyosin cytoskeleton, and extracellular matrix obstacles to lymphocyte migration. Our results support a migration model in which, following cell-matrix collisions, septins mediate the formation of cortical rings that hydraulically seal cytoplasmic compartments on each side of the passing nucleus, generating a pressure difference that propels the nucleus forward. This hydraulically driven nuclear piston actively enhances migration through confined spaces. Concurrently, the uropod emerging from the peristaltic collapse of rear compartments stabilizes directional persistence and prevents T cell repolarization. We show that such polarity stabilization boosts immune surveillance efficiency. Together, these models redefine the nucleus as an active component of the migratory engine and the uropod as a locomotion stabilizer. Furthermore, the models offer a predictive framework towards engineering of immune cell motility in complex tissue microenvironments with broad implications for cancer immunotherapy, aging, and regenerative medicine.

biophysics↗

bioRxiv2023

Lamin B Receptor Upregulation in Metastatic Melanoma Causes Cholesterol-Mediated Nuclear Envelope Fragility

Metastatic cancer cells migrate through regions of tissue confinement, causing nuclear envelope (NE) rupture and heritable DNA damage. We discovered that cells from multiple cancers have increased NE fragility in confinement and transcriptional upregulation of nuclear genes compared to benign counterparts. A bioinformatic-driven siRNA screen revealed that lamin B receptor (LBR) upregulation correlates with melanoma progression and NE fragility. Increased LBR cholesterol synthase activity causes accumulation of cholesterol in the NE, which is necessary and sufficient for nuclear deformability and NE rupture in cells confined in vitro and is associated with NE rupture in invasive cells migrating out of tumor organoids and tumors in vivo. Thus, LBR upregulation causes excess NE cholesterol, driving nuclear fragility in confined migrating melanoma cells, establishing a direct role for nuclear membrane lipid composition in metastatic cancers.

cell biology↗

bioRxiv2023

Septins Enable T Cell Contact Guidance via Amoeboid-Mesenchymal Switch

Lymphocytes exit circulation and enter in-tissue guided migration toward sites of tissue pathologies, damage, infection, or inflammation. By continuously sensing and adapting to the guiding chemo-mechano-structural properties of the tissues, lymphocytes dynamically alternate and combine their amoeboid (non-adhesive) and mesenchymal (adhesive) migration modes. However, which mechanisms guide and balance different migration modes are largely unclear. Here we report that suppression of septins GTPase activity induces an abrupt amoeboid-to-mesenchymal transition of T cell migration mode, characterized by a distinct, highly deformable integrin-dependent immune cell contact guidance. Surprisingly, the T cell actomyosin cortex contractility becomes diminished, dispensable and antagonistic to mesenchymal-like migration mode. Instead, mesenchymal-like T cells rely on microtubule stabilization and their non-canonical dynein motor activity for high fidelity contact guidance. Our results establish septins GTPase activity as an important on/off switch for integrin-dependent migration of T lymphocytes, enabling their dynein-driven fluid-like mesenchymal propulsion along the complex adhesion cues. SIGNIFICANCE STATEMENTDeciphering mechanisms of guided lymphocyte migration paves the way towards effective immunotherapies for the extracellular matrix-rich tissues, such as solid tumors. Here we demonstrate that T cell septins GTPase activity regulates both actomyosin and microtubules, alternately enhancing either of these two major motor systems. Surprisingly, the suppression of septin GTPase activity also induces a highly guided integrin-dependent mesenchymal-like migration directed by the extracellular matrix proteins. The phenomenon of guided mesenchymal-like migration of T cells relies on the microtubules and microtubule-based dynein motors that are responsible for the force generation, powering guided T cell motility. This finding opens a new perspective for future studies of septin GTPases in a context of the optimisation of T cell-based immunotherapies for the solid tissues.

cell biology↗

bioRxiv2022

Septin-Mediated Mechanobiological Reprogramming of T Cell Transmigration and 3D Motility

The all-terrain motility of lymphocytes in tissues and tissue-like gels is best described as amoeboid motility. For amoeboid motility, lymphocytes do not require specific biochemical or structural modifications to the surrounding extracellular matrix. Instead, they rely on changing shape and steric interactions with the microenvironment. However, the exact mechanism of amoeboid motility remains elusive. Here we report that septins shape T cells for amoeboid motility. Specifically, septins form F-actin and alpha-actinin-rich cortical rings at the sites of cortex-indenting collisions of T cells with the extracellular matrix. Cortical rings compartmentalize cells into chains of spherical segments that are spatially conformed to the available lumens, forming transient hourglass-shaped steric locks onto the surrounding collagen fibers. The steric lock facilitates pressure-driven peristaltic propulsion of cytosolic content by individually contracting cell segments. Our results demonstrate that septins provide microenvironment-guided partitioning of actomyosin contractility and steric pivots for amoeboid motility of T cells in tissue-like microenvironments. GLOSSARYO_LISteric interactions - interactions by the means of their spatial collision dependent on objects shapes. C_LIO_LISteric guidance - cell navigation within crowded 3D environments, determined by the available passages around and between steric hindrances. C_LIO_LIPeristaltic treadmilling - locomotion mode by the means of a repeated sequence of polarized cell cortex extension, stabilization, and retraction, accompanied by translocation of nucleus and cytoplasm via circumferential cortex contractility. C_LI Significance StatementT cells can be highly motile, searching for cognate antigens or better yet targets in chimeric antigen receptor therapy settings. However, mechanisms of motility remain elusive for T cells migrating in structurally and biochemically diverse tissues. Here we address one pivotal question of basic and clinical immunology - How T cells achieve the all-terrain motility? Here we decipher and report septin-based T cell motility in a 3D tissue-like environment. Specifically, we show that septins facilitate cell morphological responsiveness to the steric obstacles, i.e., collagen fiber-wise partitioning of actomyosin cortex contractility and cell-obstacle steric interactions. These responses coordinate peristaltic propulsion of the lymphocytes cytosolic content along its individually contracting cell segments, forming the obstacle-avoiding motility, i.e., circumnavigation, shared across various tested lymphocytes.

biophysics↗

bioRxiv2021

A myosin chaperone, UNC-45A, is a novel regulator of intestinal epithelial barrier integrity and repair

The actomyosin cytoskeleton serves as a key regulator of the integrity and remodeling of epithelial barriers by controlling assembly and functions of intercellular junctions and cell-matrix adhesions. While biochemical mechanisms that regulate activity of non-muscle myosin II (NM-II) in epithelial cells have been extensively investigated, little is known about assembly of the contractile myosin structures at the epithelial adhesion sites. UNC-45A is a cytoskeletal chaperone that is essential for proper folding of NM II heavy chains and myofilament assembly. We found abundant expression of UNC-45A in human intestinal epithelial cell (IEC) lines and in the epithelial layer of the normal human colon. Interestingly, protein levels of UNC-45A were decreased in colonic epithelium of patients with ulcerative colitis. CRISPR/Cas9-mediated knock-out of UNC-45A in HT-29 and SK-CO15 IEC disrupted epithelial barrier integrity, impaired assembly of epithelial adherence and tight junctions and attenuated cell migration. Consistently, decreased UNC-45 expression increased permeability of the Drosophila gut in vivo. The mechanisms underlying barrier disruptive and anti-migratory effects of UNC-45A depletion involved disorganization of the actomyosin bundles at epithelial junctions and the migrating cell edge. Loss of UNC-45A also decreased contractile forces at epithelial junctions and matrix adhesions. Expression of deletion mutants revealed roles for the myosin binding domain of UNC-45A in controlling IEC junctions and motility. Our findings uncover a novel mechanism that regulates integrity and restitution of the intestinal epithelial barrier, which may be impaired during mucosal inflammation.

cell biology↗

bioRxiv2021

Viscoelastic Parameterization of Human Skin Cells to Characterize Material Behavior at Multiple Timescales

Countless biophysical studies have sought distinct markers in the cellular mechanical response that could be linked to morphogenesis, homeostasis, and disease. Here, a novel iterative-fitting methodology is used to investigate the viscoelastic behavior at multiple relaxation times of human skin cells under physiologically relevant conditions. Past investigations often involved parameterizing linear elastic relationships and assuming purely Hertzian contact mechanics. However, linear elastic treatment fails to capture and properly account for the rich temporal information available in datasets. We demonstrate the performance superiority of the proposed iterative viscoelastic characterization method over standard open-search approaches. Our viscoelastic measurements revealed that 2D adherent metastatic melanoma cells exhibit reduced elasticity compared to normal counterparts--melanocytes and fibroblasts, whereas are significantly less viscous than only fibroblasts over timescales spanning three orders of magnitude. Interestingly, melanocytes are stiffer than melanoma cells, while being the less viscous cells measured. The measured loss angle indicates clear differential viscoelastic responses across multiple timescales between the measured cells. We propose the use of viscoelastic properties at multiple timescales as a mechanical biomarker of diseases. Altogether, this method provides new insight into the complex viscoelastic behavior of metastatic melanoma cells relevant to better understanding cancer metastasis aggression.

biophysics↗

bioRxiv2021

TRIOBP promotes bidirectional radial stiffness gradients within the organ of Corti

Hearing depends on complex mechanical properties of the inner ear sensory epithelium. Yet, the individual contributions of different cell types to the stiffness spectrum of the sensory epithelium have not been thoroughly investigated. Using sub-100 nanometer spatial resolution PeakForce Tapping Atomic Force Microscopy (PFT-AFM), we mapped the Youngs modulus (stiffness) of the apical surface of different cells of freshly-dissected cochlear epithelium from wild-type mice and mice lacking the F-actin bundling protein TRIOBP-5 or TRIOBP-4 and TRIOBP-5. Variants of the genes encoding human and mouse TRIOBP are associated with deafness. We show that TRIOBP deficiency affects formation of supporting cell apical phalangeal microfilaments and bundled cortical F-actin of hair cell cuticular plates, softening the apical surface of the sensory epithelium. Unexpectedly, high-resolution PFT-AFM-mapping also revealed previously unrecognized reticular lamina radial stiffness gradients of opposite orientations in wild-type supporting and hair cells. Deafness-associated TRIOBP deficiencies significantly modified these bidirectional radial stiffness gradients.

biophysics↗

bioRxiv2021

Mechanical counterbalance of kinesin and dynein motors in microtubular network regulates cell mechanics, 3D architecture, and mechanosensing

Microtubules (MTs) and MT motor proteins form active 3D networks made of unstretchable cables with rod-like bending mechanics that provide cells with a dynamically changing structural scaffold. In this study, we report an antagonistic mechanical balance within the dynein-kinesin microtubular motor system. Dynein activity drives microtubular network inward compaction, while isolated activity of kinesins bundles and expands MTs into giant circular bands that deform the cell cortex into discoids. Furthermore, we show that dyneins recruit MTs to sites of cell adhesion increasing topographic contact guidance of cells, while kinesins antagonize it via retraction of MTs from sites of cell adhesion. Actin-to-microtubules translocation of septin-9 enhances kinesins-MTs interactions, outbalances activity of kinesins over dyneins and induces discoid architecture of cells. These orthogonal mechanisms of MT network reorganization highlight the existence of an intricate mechanical balance between motor activities of kinesins and dyneins that controls cell 3D architecture, mechanics, and cell-microenvironment interactions.

biophysics↗