Biology subjects

Rosenblatt, J.

Publications and source records attributed to Rosenblatt, J..

12 recordsLinked to original sources

bioRxiv2026

Starvation improves epithelial fitness by selectively extruding DNA damaged cells

During homeostasis, crowded cells with the lowest energy levels are eliminated by extrusion via Piezo1 signalling to maintain constant cell numbers. However, crowding-induced extrusion does not necessarily remove damaged or otherwise unfit cells. Here, we show that glucose or glutamine starvation triggers a rapid, regulated wave of extrusion, called starvation-induced cell extrusion (STICE), that selectively eliminates cells bearing DNA damage markers via a p53-dependent, Piezo1-independent pathway, improving monolayer fitness. Unlike non-extruding cells, which recycle contents through autophagy and lysosomal digestion, p53-activated cells instead use LC3 to drive lysosomal exocytosis, promoting extrusion signalling. By eliminating defective and transformed cells, STICE confers resistance to damage and apoptotic stimuli in the remaining monolayer. STICE thus acts as a tissue-level analogue of autophagy: rather than improving individual cells by digesting and recycling damaged components, it improves tissue fitness by eliminating substandard cells.

cell biology↗

bioRxiv2026

Piezo1 balances focal and reticular adhesions to enable EGFR clathrin-mediated endocytosis

Cells attach to the extracellular matrix through distinct integrin-mediated adhesive structures, including force-transmitting focal adhesions (FAs) and clathrin-enriched reticular adhesions (RAs). FAs enable mesenchymal cell migration and disassemble at mitotic entry, whereas RAs impede migration, persist during mitosis, and contribute to clathrin-mediated endocytosis (CME) as they disassemble. FAs grow with RhoA contractility, whereas RAs shrink, but the mechanisms coordinating these opposing responses remain unclear. Here, we identify the mechanically activated ion channel Piezo1 as a master regulator of FA/RA balance. Piezo1-dependent calcium influx activates the Src family kinase Fyn, which activates two actin polymerization pathways: FA and stress fiber growth via VAV2-RhoA and RA disassembly via N-WASP-Arp2/3. Inhibition or knockdown of Piezo1, Fyn, or VAV2 decreases FA size and increases RA coverage. Critically, cells lacking Piezo1 fail to internalize ligand-activated EGFR on stiff substrates despite normal CME on soft substrates, establishing an essential role for Piezo1 in EGFR CME mechanoadaption. Our findings reveal Piezo1 as the mechanosensor linking membrane tension to coordinated actin polymerization pathways that co-regulate cell-matrix adhesion and endocytosis. Given that CME contributes to viral entry into host cells and cancer resistance to anti-EGFR antibody therapy, targeting the Piezo1-RA-CME axis may offer novel therapeutic opportunities.

cell biology↗

bioRxiv2025

Human airway epithelia clear rhinovirus-infected cells using two waves of cell extrusion

Epithelial barriers represent the first line of defence against pathogens, yet their role in innate immunity is typ-ically relegated to pathogen detection and immune cell recruitment. This perspective ignores a fundamental evolutionary principle: epithelia defended against pathogens long before complex immune systems evolved. Here, we demonstrate that human bronchial epithelial monolayers retain this ancestral capacity, autono-mously clearing rhinovirus (RV) within 24 hours by selectively extruding infected cells--a process we term virus-induced cell extrusion (VICE). VICE occurs in two waves: a rapid response occurring independently of virus entry, followed by a replication-dependent wave. Barrier-defective epithelia that cannot extrude fail to clear RV. While extrusion maintains barrier integrity and eliminates local infection, it also expels virus-laden cells, promoting transmission. Thus, VICE enables leukocyte-independent epithelial defence while inadver-tently promoting viral transmission, reflecting an evolutionary strategy that prioritizes barrier integrity over containment. These findings redefine epithelia as central players in viral pathogenesis and host protection.

cell biology↗

bioRxiv2025

Inhibiting epithelial cell extrusion and inflammation synergistically reverses asthmatic airway remodelling

Airway smooth muscle (ASM) hyperresponsiveness is the defining feature of asthma, yet neither its origins nor the processes that establish and maintain it are understood. Here, using a mouse model, we show that hyperresponsiveness arises from ASM realignment into dense, parallel bundles reinforced by excess extracellular matrix, a fundamental remodelling rather than mere amplification of existing contractile ASM. This remodelling is initiated and sustained by a mechanical feedforward cycle. Allergen treatment initiates a contraction-relaxation cycle that realigns ASM into a bronchoconstrictive state. As bronchoconstriction triggers crowding and excess airway epithelial cell extrusion 1, the wounding then locks ASM into a hypercontractile architecture that drives further constriction. Gadolinium, a mechanosensitive channel blocker that inhibits extrusion, prevents this remodelling and hyperresponsiveness--unlike the corticosteroid budesonide. Critically, in mice with fully established disease, gadolinium reverses all asthmatic features and restores normal airway function, while budesonide alone cannot. Budesonide, however, synergises with gadolinium to normalise protein and gene expression. These findings reframe asthma pathogenesis as a mechanically driven, pharmacologically reversible process -- suggesting that asthma may be curable rather than merely treatable.

cell biology↗

bioRxiv2023

The mechanics of bronchoconstriction cause airway epithelial damage and inflammation by excess crowding-induced extrusion

Asthma is deemed an inflammatory disease, yet the defining diagnostic symptom is mechanical bronchoconstriction. We previously discovered a conserved process that drives homeostatic epithelial cell death in response to mechanical cell crowding called cell extrusion(1, 2). Here, we show that the pathological crowding of a bronchoconstrictive attack causes so much epithelial cell extrusion that it damages the airways, resulting in inflammation and mucus secretion. While relaxing airways with the rescue treatment albuterol did not impact these responses, inhibiting live cell extrusion signaling during bronchoconstriction prevented all these symptoms. Our findings propose a new etiology for asthma, dependent on the mechanical crowding of a bronchoconstrictive attack. Our studies suggest that blocking epithelial extrusion, instead of ensuing downstream inflammation, could prevent the feed-forward asthma inflammatory cycle.

cell biology↗

bioRxiv2023

Voltage-dependent volume regulation controls epithelial cell extrusion and morphology

Epithelial cells work collectively to provide a protective barrier, yet also turn over rapidly by cell death and division. If the number of dying cells does not match those dividing, the barrier would vanish, or tumors can form. Mechanical forces and the stretch-activated ion channel (SAC) Piezo1 link both processes; stretch promotes cell division and crowding triggers cell death by initiating live cell extrusion1,2. However, it was not clear how particular cells within a crowded region are selected for extrusion. Here, we show that individual cells transiently shrink via water loss before they extrude. Artificially inducing cell shrinkage by increasing extracellular osmolarity is sufficient to induce cell extrusion. Pre-extrusion cell shrinkage requires the voltage-gated potassium channels Kv1.1 and Kv1.2 and the chloride channel SWELL1, upstream of Piezo1. Activation of these voltage-gated channels requires the mechano-sensitive Epithelial Sodium Channel, ENaC, acting as the earliest crowd-sensing step. Imaging with a voltage dye indicated that epithelial cells lose membrane potential as they become crowded and smaller, yet those selected for extrusion are markedly more depolarized than their neighbours. Loss of any of these channels in crowded conditions causes epithelial buckling, highlighting an important role for voltage and water regulation in controlling epithelial shape as well as extrusion. Thus, ENaC causes cells with similar membrane potentials to slowly shrink with compression but those with reduced membrane potentials to be eliminated by extrusion, suggesting a chief driver of cell death stems from insufficient energy to maintain cell membrane potential.

cell biology↗

bioRxiv2022

Physical confinement promotes mesenchymal trans-differentiation of invading transformed cells in vivo

Metastasis is tightly linked with poor cancer prognosis, yet it is not clear how transformed cells become invasive carcinomas. We previously discovered that single KRasV12-transformed cells can invade directly from the epithelium by basal cell extrusion. During this process, cells de-differentiate by mechanically pinching off their epithelial determinants, but how they trans-differentiate into a migratory, mesenchymal phenotype is not known. Here, we demonstrate that basally extruded KRasV12-expressing cells become significantly deformed as they invade the zebrafish body. Decreasing the confinement that cells experience after they invade reduces the percentage of KRasV12 cells that trans-differentiate into mesenchymal cell types, while higher confinement increases this percentage. Additionally, increased confinement promotes accumulation of internal masses over time. Altogether, our results suggest that mechanical forces drive not only de-differentiation of KRasV12-transformed epithelial cells as they invade but also contribute to their re-differentiation into mesenchymal phenotypes that contribute to distant metastases.

cancer biology↗

bioRxiv2022

Piezo1 activates non-canonical EGFR endocytosis and signaling

SummaryEGFR-ERK signaling controls cell cycle progression during development, homeostasis, and disease. Both the soluble extracellular ligand, EGF, and mechanical inputs like matrix stiffness, cell adhesion, or stretch activate EGFR-ERK signaling. However, the molecules transducing mechanical forces into EGFR signaling remain unidentified. We previously found that stretch promotes mitosis by mechanically activating the ion channel Piezo1 to trigger ERK signaling. Here, we show that Piezo1 provides the missing link to mechanical EGFR-ERK activation. Both EGF ligand and mechanical or agonist activation of Piezo1 trigger clathrin-mediated endocytosis of EGFR and ERK activation, established markers of EGFR signaling. However, while EGF stimulation requires canonical EGFR tyrosine autophosphorylation, EGFR activation by Piezo1 instead requires Src-p38 kinase-dependent serine EGFR phosphorylation. Additionally, in contrast to the homeostatic signaling downstream EGF activation, direct agonist stimulation of Piezo1 promoted cell cycle re-entry and proliferation in mouse airway epithelia ex vivo via long-term nuclear accumulation of ERK, AP-1 (FOS and JUN), and YAP, typical of regenerative and malignant signaling. Our results suggest two modes of EGFR signaling: basal EGF-dependent signaling via tyrosine autophosphorylation and mechanically activated Piezo1-dependent signaling via serine phosphorylation, resulting in sustained proliferation, critical to repair, regeneration, and cancer growth. Given the limited success of tyrosine kinase inhibitors in cancer, this new axis may provide a more relevant target for cancer treatment.

cell biology↗

bioRxiv2022

Automated assessment reveals extinction risk of reptiles is widely underestimated across space and phylogeny

The Red List of Threatened Species, published by the International Union for Conservation of Nature (IUCN), is a crucial tool for conservation decision making. However, despite substantial effort, numerous species remain unassessed, or have insufficient data available to be assigned a Red List threat category. Moreover, the Red Listing process is subject to various sources of uncertainty and bias. The development of robust automated assessment methods could serve as an efficient and highly useful tool to accelerate the assessment process and offer provisional assessments. Here we aimed to: 1) present a machine learning based automated threat assessment method that can be used on less known species; 2) offer provisional assessments for all reptiles - the only major tetrapod group without a comprehensive Red List assessment; and 3) evaluate potential effects of human decision biases on the outcome of assessments. We use the method presented here to assess 4,369 reptile species that are currently unassessed or classified as Data Deficient by the IUCN. Our models range in accuracy from 88% to 93% for classifying species as threatened/non-threatened, and from 82% to 87% for predicting specific threat categories. Unassessed and Data Deficient reptiles were more likely to be threatened than assessed species, adding to mounting evidence that they should be considered threatened by default. The overall proportion of threatened species greatly increased when we included our provisional assessments. Assessor identities strongly affected prediction outcomes, suggesting that assessor effects need to be carefully considered in extinction risk assessments. Regions and taxa we identified as likely to be more threatened should be given increased attention in new assessments and conservation planning. Lastly, the method we present here can be easily implemented to help bridge the assessment gap on other less known taxa.

ecology↗

bioRxiv2019

Cell cycle S-phase arrest drives cell extrusion

Cell extrusion is a process of cell elimination in which a cell is squeezed out from its tissue of origin. Extrusion occurs in organisms as diverse as sponges, nematodes, insects, fish and mammals. Defective extrusion is linked to many epithelial disorders, including cancer. Despite broad occurrence, cell-intrinsic triggers of extrusion conserved across phyla are generally unknown. We combined genome-wide genetic screens with live-imaging studies of C. elegans embryos and mammalian epithelial cultures and found that S-phase arrest induced extrusion in both. Cells extruded from C. elegans embryos exhibited S-phase arrest, and RNAi treatments that specifically prevent S-phase entry or arrest blocked cell extrusion. Pharmacological induction of S-phase arrest was sufficient to promote cell extrusion from a canine epithelial monolayer. Thus, we have discovered an evolutionarily conserved cell-cycle-dependent trigger of cell extrusion. We suggest that S-phase-arrest induced cell extrusion plays a key role in physiology and disease.

cell biology↗

bioRxiv2018

Basal extrusion drives cell invasion and mechanical stripping of E-cadherin

Metastasis is the predominant reason that patients succumb to cancer, yet the mechanisms that drive initial tumor cell invasion are poorly understood. We previously discovered that crowding-induced apical extrusion drives most epithelial cell death, critical to maintaining constant cell densities. Oncogenic mutations can disrupt apical cell extrusion, instead causing masses to form and aberrant basal extrusion. Using transparent zebrafish epidermis to model simple epithelia, we can image invasion events live at high resolution. We find that KRas/p53-transformed cells form masses and, at completely independent sites, invade by basal extrusion. Basal extrusion also causes invading cells to simultaneously mechanically shed their entire apical membranes and E-cadherin. Once cells invade the underlying tissue, they migrate throughout the body, divide, enter the bloodstream, and become different cell types. KRas-transformation makes cells intrinsically invasive by increasing basal extrusion rates; collaborating mutations in p53 allow disseminated cells to survive at distant sites.

cancer biology↗

bioRxiv2018

Endothelia extrude apoptotic cells to maintain a constant barrier

The vascular system is lined with endothelial cells that, although only existing in a single monolayer, are key in the regulation of vascular barrier function. One of the major challenges these cells face is a routine exposure to environmental stressors that can induce apoptosis. Uncontrolled apoptosis in the endothelial monolayer threatens the ability of the cells to maintain their barrier function, resulting in vascular dysfunction. Therefore, we sought to identify ways in which endothelia maintain a cohesive monolayer during apoptotic events. We found that endothelial cells fated die will undergo a process of apoptotic cellular extrusion, similar to what has been described in the epithelium. We further show that endothelial extrusion uses a conserved S1P-S1PR2-RhoA signaling pathway in order to induce the formation of an actin ring that contracts closed, forcing the dying cell out of the monolayer while simultaneously filling in the gap left behind. Thus, endothelial extrusion successfully removes an apoptotic cell before it compromises the monolayer, preserving the barrier function.

cell biology↗