Biology subjects

Parton, R. G.

Publications and source records attributed to Parton, R. G..

At least 19 recordsLinked to original sources

bioRxiv2026

Apical-Out Ileal Organoids: A Versatile Platform for Probing Gut-Nanomaterial Interactions

The human ileal epithelium forms a critical interface governing interactions with luminal microorganisms and nanomaterials, yet physiologically relevant in vitro models with accessible apical surfaces remain limited. Here, human apical-out ileoids derived from healthy ileal biopsies are established as a platform that recapitulates the architecture and complexity of the native ileal epithelium. Assessment of donor- and passage-dependent variability identifies a representative ileoid line and a robust culture window. Integrated proteomic, imaging, ultrastructural, and functional analyses demonstrate preservation of key epithelial features, including brush-border organization, barrier integrity, absorptive capacity, and multiple endocytic pathways. Intact ileoids internalize nanoparticles of distinct surface charge, including empty lipid nanoparticles compositionally matched to approved mRNA vaccine formulations, establishing that uptake can be quantified across an unperturbed apical surface. This uptake is restrained by a retained mucin-rich glycocalyx. Cleavage of surface-attached mucins selectively enhances uptake of negatively charged nanoparticles, leaving near-neutral and positively charged nanoparticles unchanged, and increasing entry of Salmonella bacteria. These findings reveal the glycocalyx as a charge-selective regulator of epithelial uptake. In conclusion, our study provides a foundation for nanoparticle-epithelium investigations using human apical-out ileoids, and a versatile, translationally relevant platform for nanomedicine delivery, host-microbe interactions, and epithelial transport.

cell biology↗

bioRxiv2026

Cardiomyocyte caveolae govern myocardial function and sex-dependent regulation of ventricular compliance and resilience via cavin-1

AimsCaveolae are plasmalemmal microdomains regulating stretch-dependent, nitric oxide (NO), and other signalling pathways governing myocardial structure, function and resilience. We have reported that global deletion of the scaffold protein cavin-1 disrupts caveolar biogenesis and impairs ventricular compliance and tolerance to ischaemic injury. However, cardiomyocyte-specific and sex-dependent roles of cavin-1 and caveolar complexes remain unresolved. Methods and ResultsWe generated a floxed Cavin-1 transgenic mouse, enabling cardiomyocyte-specific knockdown via adeno-associated virus (AAV) mediated expression of iCre recombinase driven by a cardiac-specific troponin T promoter. Knockdown was confirmed by RNA, protein, and immunofluorescence analyses, and cardiac function was assessed via echocardiography, left ventricular pressure-volume (PV) catheterisation, and ex vivo PV analysis of perfused hearts. Conditionally deleted hearts and myocytes exhibited up to 50% knockdown of Cavin-1 mRNA together with 15% deficiency in muscle-specific Caveolin-3, 70% depletion of caveolae, and mislocalisation of NO synthase (NOS) within cardiomyocytes. This was associated with elevated heart rate and shortened PR interval; reduced intraventricular and systolic blood pressures and peripheral resistance; and sex-dependent impairment of ventricular filling (females only). Diastolic dysfunction was detectable ex vivo, to a greater extent in male vs. female hearts. Mechanisms were sex-dependent, linked to interstitial fibrosis in females and NOS overactivity (inhibited by 100 {micro}M L-NAME) in males. Female hearts also exhibited increased susceptibility to ischaemia-reperfusion injury. Coronary function appeared preserved in both sexes, with intact reactive hyperaemic responses. ConclusionThis model identifies cardiomyocyte caveolae and cavin-1 as key determinants of myocardial function and compliance, involving sex-dependent remodelling and NOS signalling. By linking cardiomyocyte disruption to whole-organ and -body dysfunction, this model provides mechanistic insight into impaired function in heart failure and ageing. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=117 SRC="FIGDIR/small/717104v1_ufig1.gif" ALT="Figure 1"> View larger version (37K): org.highwire.dtl.DTLVardef@51bfe4org.highwire.dtl.DTLVardef@10d4323org.highwire.dtl.DTLVardef@1b2baa7org.highwire.dtl.DTLVardef@fc5f21_HPS_FORMAT_FIGEXP M_FIG C_FIG

physiology↗

bioRxiv2026

Defensive lipid droplets are PUFA reservoirs driving bacterial clearance and inflammation

Lipid droplets (LDs) rapidly form in infected cells to participate in the defence against microbes. Here, we investigate the involvement of LD lipids in these immune responses. Comparative shotgun and targeted lipidomics demonstrate that in vivo host LDs accumulate polyunsaturated fatty acids (PUFAs). PUFAs arrive at cells from the bloodstream to be further metabolised into complex PUFAs accrued by LD-triglycerides and -phospholipids. Host lipid metabolism is transcriptionally controlled by rapid, transient, and intricate immune programs initiated by pathogen-associated molecular patterns and relayed by cytokines such as interferons (type I and II), interleukins (IL-1{beta}), and tumour necrosis factor. When this lipid and signalling environment is reproduced in cultured macrophages, newly formed LDs accumulate defensive proteins, coordinate the synthesis of complex PUFAs, and become PUFA reservoirs and suppliers. Among LD-PUFAs, the {omega}-6 arachidonic acid is the most actively metabolised during the initial phases of innate immunity. Released from LDs by adipose triglyceride lipase, arachidonic acid is used by macrophages for prostaglandin synthesis, bacterial phagocytosis, and elimination of microbes. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=163 HEIGHT=200 SRC="FIGDIR/small/711356v2_ufig1.gif" ALT="Figure 1"> View larger version (107K): org.highwire.dtl.DTLVardef@14d65eorg.highwire.dtl.DTLVardef@5ecc1org.highwire.dtl.DTLVardef@fa99e5org.highwire.dtl.DTLVardef@8d9632_HPS_FORMAT_FIGEXP M_FIG C_FIG

cell biology↗

bioRxiv2025

Membrane contacts between caveolae and the endoplasmic reticulum regulate uptake and metabolic trapping of long-chain fatty acids

The vital process of cellular fatty acid metabolism involves uptake, metabolic trapping and storage of long-chain fatty acids (LCFAs) in different lipid species. Although several different enzymes like transporters and acyl-CoA synthetases are involved, the sequential mechanistic steps of the process are poorly understood. Here, we have addressed the role of the caveola coat protein caveolin1 and the acyl-CoA synthetase FATP1 in the process as both have major impacts in the uptake and storage of fatty acids in vivo and in vitro. Using live cell microscopy and mass spectrometry-based quantification of LCFA metabolism, we found that FATP1-mediated uptake and metabolic processing of LCFAs is coupled to, and dependent on caveolin1. Furthermore, both proteins stimulate the incorporation of LCFA into phospholipids and triacylglycerol, but not in sphingolipids. Using correlative light and electron microscopy we found that membrane contact sites are formed between FATP1-enriched endoplasmic reticulum (ER) and caveolae. Analysis of their temporal stability showed that they are dynamic but frequently persist over minutes. We propose that caveolae directly couple the plasma membrane (PM) to the ER for directed LCFA transport and metabolic processing.

cell biology↗

bioRxiv2025

Integrin β1-Talin1 at focal adhesions underpin uncontrolled endothelial cell enlargement in live cerebral cavernous malformation vasculature

Cerebral cavernous malformations (CCMs) are vascular anomalies caused by loss of CCM gene function and consequent hyperactivation of MEKK3-KLF2/4 signaling in endothelial cells. Excess integrin {beta}1 activity has been associated with lesion growth, yet the precise mechanistic and biomechanical roles of the integrin-KLF2/4 hierarchy in CCM cellular pathogenesis are not fully understood. Using live imaging of endothelial Vinculin in Ccm1-deficient zebrafish, we demonstrate excessive, mechanically active focal adhesions in an in vivo model of CCM pathology. We validate this in CCM1-deficient endothelial cells and show a redistribution of mechanical tension from cell-cell junctions to focal adhesions. Genetic deletion of Talin1 to decouple focal adhesions from the cell cortex and inhibit integrin {beta}1 signaling demonstrates the integrin {beta}1-Talin1 complex is essential for vascular malformations in ccm1 mutants by driving endothelial cell enlargement. We show integrin {beta}1-Talin1 act independent or downstream of KLF2/4, rather than upstream as previously suggested. Thus, we reposition the role of integrin {beta}1-Talin1 in CCM pathogenesis, demonstrating an essential function in driving cell enlargement, which underpins lesion growth.

cell biology↗

bioRxiv2025

An efficient eukaryotic cell-free expression and correlative cryo-electron tomography platform for structural biology of macromolecular complexes

Cell-free expression using Leishmania tarentolae lysates allows rapid expression of eukaryotic proteins directly from DNA templates. We develop a pipeline that combines cell-free expression system with cryogenic fluorescence microscopy that we term CC-FLEXCET (Correlative Cell-Free Leishmania EXpression and Cryo-Electron Tomography), to target and visualize expressed protein complexes by cryo-electron tomography at high resolution. We demonstrate the utility of this method by structurally characterising the filaments of the full-length apoptosis-associated speck like protein containing CARD (ASC) protein. Cell-free expression of ASC results in a polymeric structure characteristic of its cellular speck assembly. Sub-tomogram averaging allows us to resolve both the pyrin domain (PYD) to medium resolution, and show, for the first time, the arrangement of the flexibly linked caspase recruitment domain (CARD). Finally, we observed an interaction between the ASC filament and the L. tarentolae ribosome. Using template matching and quantitative approaches, we characterise this interaction and determine that there is a random structural association between the filament and the ribosome, with 57% of ribosomes oriented with the LSU toward the ASC polymer. CC-FLEXCET facilitates structural analysis of macromolecules and protein-lipid assemblies without need of purification, providing a pipeline from DNA template to protein expression to cryo-tilt series acquisition, within a single day.

biochemistry↗

bioRxiv2025

A structural transition ensures robust formation of skeletal muscle

During organ development cells undergo significant morphological and positional changes. Yet, by the end of organogenesis, internal organ structure is typically robustly defined, with cells tightly packed. It remains an open question as to how the three-dimensional (3D) internal structure of an organ emerges reliably, particularly when there are multiple cell types interacting and dynamic boundary constraints. Here, we utilise quantitative live imaging and 3D morphological measures of the developing zebrafish myotome to unravel how early muscle organisation emerges. Contrary to the textbook view of muscle fibres as cylindrical, myocytes undergo an ordered chiral twist, the direction and magnitude of which depends on their position within the myotome. Further, cells skew and rearrange, seemingly to facilitate close packing of neighbouring muscle fibres. Cell movement undergoes a rapid decline in speed once the cells span the myotome segment. We find that cell packing is altered in mutants that disrupt cell fate or cell fusion, even though the final muscle segments remain largely confluent. Biophysical perturbation reveals that the cells are mechanically plastic, able to adjust to changes in the local cellular environment and boundary constraints. Taking these results together, we propose that the early myotome undergoes a structural transition, from a fluid-like state into a frozen state, resembling glass-like behaviour. Cellular plasticity in response to varying boundary constraints may be a general mechanism for ensuring robust organ morphogenesis in dense 3D tissues.

developmental biology↗

bioRxiv2025

A Standardized Protocol to Investigate Trans-Endothelial Trafficking in Zebrafish: Nano-bio Interactions of PEG-based Nanoparticles in Live Vasculature

Trans-endothelial transport of nanoparticles remains poorly characterized in live organisms. The zebrafish is a well-established model for direct in vivo imaging; however, standardized controls are not consistently applied across studies. Here, we developed a standardized protocol to assess nanoparticle trans-endothelial trafficking in live zebrafish. We tested a range of tracers and identified 2000 kDa dextran as an optimal control for standardizing microinjections and quantifying nanoparticle transport in a systematic unbiased manner. As validation, we identified the early physiological trans-endothelial transport pathways in zebrafish embryos using 40 kDa dextran as a nanoparticle surrogate. Using our workflow, we assessed the extravasation of 3, 7, 32 and 47 nm polyethylene glycol (PEG)-based nanoparticles. Using cAMP stimulation to restrict paracellular routes, and inhibitors to impede dynamin-dependent endocytosis, we demonstrated that PEG-based hyperbranched polymer (HBP) nanoparticles of 3 to 7 nm traverse the endothelial barrier via paracellular routes and 32 and 47 nm PEG micelles adopt dynamin- dependent endocytic trafficking over paracellular transport. We characterized the emergence of caveolae in the vasculature up to 17 days post-fertilization (dpf) using a cavin1b knock-in zebrafish line. Using cavin1a/cavin1b double knockout (DKO) zebrafish, and tumor-bearing Cavin-1 null mice, we showed that caveolae do not contribute to the transvascular transport of these PEG-based nanoparticles. This work highlights the rigour of the standardized protocol for assessing nanoparticle trans-endothelial transport in the live zebrafish, providing a systematic approach for quantification using a standardized control.

cell biology↗

bioRxiv2025

New glucose-abstaining Chlorella algae doubles mammalian cell culture longevity, boosts performance and drops serum needs enabling scaled applications.

Mammalian cell culture technologies are crucial for recombinant protein production, organoid generation, medical applications, and the generation of in vitro cultivated meat. However, they are limited by high costs, vascular O2 provision, and the resultant inhibition of 3D tissue formation. Effective media usage along with oxygenation and waste management to extend culture health and longevity are key to improving all three. Microalgae, utilizing organic or inorganic CO2, produce O2 from light which complements oxygen-consuming and CO2-respiring mammalian cells and tissue culture. However, common microalgal cultivation conditions differ in temperature and salinity from mammalian cell cultivation environments, making co-cultivation short-lived and challenging. We screened several different microalgae species to identify locally isolated Chlorella BDH-1 as candidate that has high growth rates in mammalian culture conditions while, unlike other Chlorella species, does not compete for glucose as an energy source. In mammalian cell co-culture, BDH1 reduces cellular waste products, stabilizes pH, doubles culture longevity, increases growth performance up to 80%, and reduces expensive and ethically challenging foetal bovine serum requirements. Chlorella BDH-1 was also non-inflammatory and tolerant of clinical antibiotics. Collectively, mammalian cell/BDH1 co-cultivation improves tissue culture health and reduces costs, paving the path for applications in the biotechnology and medical sectors.

cell biology↗

bioRxiv2025

Lipid packing frustration in the outer leaflet of the plasma membrane prevents scission of caveolae

Lipid packing is a fundamental characteristic of bilayer membranes. It affects all membrane-associated processes ranging from curvature generation to membrane fission. Yet, we lack detailed mechanistic understanding of how lipid packing directly affects these processes in cellular membranes. Here, we address this by focusing on caveolae, small 0-shaped invaginations of the plasma membrane which serve as key regulators of cellular lipid sorting and mechano-responses. In addition to caveolae coat proteins, the lipid membrane is a core component of caveolae that critically impacts both the biogenesis, morphology and stability of such membrane invaginations. We show that the small compound Dyngo-4a adsorbs and inserts into the membrane, resulting in a dramatic dynamin-independent inhibition of caveola dynamics. Analysis of model membranes in combination with molecular dynamics simulations revealed that a substantial amount of Dyngo-4a was inserted and positioned at the level of cholesterol in the bilayer affecting lipid order in a cholesterol dependent manner. Dyngo-4a-treatment resulted in decreased lipid packing of the plasma membrane. This prevented caveolae internalization and lateral diffusion without affecting their morphology, associated proteins, or the overall cell stiffness. Artificially increasing plasma membrane cholesterol levels was found to counteract the block in caveola dynamics caused by Dyngo-4a-mediated lipid packing frustration. Therefore, we propose that the outer leaflet lipid packing of cholesterol in the the plasma membrane critically contributes to the confinement of caveolae to the plasma membrane. Significance statementLarsson et al., demonstrate that lipid packing critically impacts the stability of small 0-shaped plasma membrane cavities termed caveolae. The plasma membrane (PM) release of caveolae is dynamin independent and halted by PM incorporation of the small compound Dyngo-4a, which leads to decreased lipid packing as characterized by the authors. The block in caveola internalization can be counteracted by increased PM levels of cholesterol which is enriched in caveolae and increases the lipid packing. This proof-of-principle study shows that lipid packing controls membrane budding generating membrane vesicles that remain stably associated with the membrane for an extended period of time.

cell biology↗

bioRxiv2024

Targeted glycophagy ATG8 therapy for diabetic heart disease

Diabetic heart disease is highly prevalent and is associated with the early development of impaired diastolic relaxation. The mechanisms of diabetic heart disease are poorly understood and it is a condition for which there are no targeted therapies. Recently, disrupted glycogen-autophagy (glycophagy) and glycogen accumulation have been identified in the diabetic heart. Glycophagy involves glycogen receptor binding and linking with an ATG8 protein to locate and degrade glycogen within an intracellular phago-lysosome. Here we show that glycogen receptor protein STBD1 (starch-binding-domain-protein-1) is mobilized early in the cardiac glycogen response to metabolic challenge in vivo, and that deficiency of a specific ATG8 family protein, Gabarapl1 ({gamma}-aminobutyric-acid-receptor-associated-protein-like-1) is associated with diastolic dysfunction in diabetes. Gabarapl1 gene delivery treatment remediated cardiomyocyte and cardiac diastolic dysfunction in type 2 diabetic mice and diastolic performance of diabetic human iPSC-derived cardiac organoids. We identify glycophagy dysregulation as a mechanism and potential treatment target for diabetic heart disease.

physiology↗

bioRxiv2024

Cavin1 binding nanobodies reveal structural flexibility and regulated interactions of the N-terminal coiled-coil domain

Caveolae are abundant plasma membrane structures that regulate signalling, membrane homeostasis, and mechanoprotection. Their formation is driven by caveolins and cavins and their coordinated interactions with lipids. We have developed nanobodies against the trimeric HR1 coiled-coil domain of Cavin1. We identify specific nanobodies that do not perturb Cavin1 membrane binding and localise to caveolae when expressed in cells. The crystal structure of a nanobody HR1 complex reveals a symmetric 3:3 architecture as validated by mutagenesis. In this structure, the C-terminal half of the HR1 domain is disordered suggesting the nanobody has stabilised an open conformation previously identified as important for membrane interactions. A phosphomimic mutation in a Thr-Ser pair proximal to this region reveals selective regulation of Cavin2/Cavin3 association. These studies provide new insights into Cavin domains required for assembly of multiprotein caveolar assemblies and describe new nanobody tools for structural and functional studies of caveolae. SUMMARY STATEMENTNanobodies are reported that can label the Cavin1 protein and caveola structures in cells.

cell biology↗

bioRxiv2024

Vascular mural cells protect the adult brain from haemorrhage but do not control the blood-brain barrier in developing zebrafish

The blood-brain barrier (BBB) protects the brain from circulating metabolites and plays central roles in neurological diseases. Endothelial cells (ECs) of the BBB are enwrapped by mural cells including pericytes and vascular smooth muscle cells (vSMCs) that regulate angiogenesis, vessel stability and barrier function. To explore mural cell control of the BBB, we investigated neurovascular phenotypes in zebrafish pdgfrb mutants that lack brain pericytes and vSMCs. As expected, mutants showed an altered cerebrovascular network with mispatterned capillaries. Unexpectedly, mutants displayed no BBB leakage at larval stages of development. This demonstrates that pericytes and vSMCs do not control BBB function in developing zebrafish. Instead, we observed juvenile and adult BBB disruption occurring at "hotspot" focal hemorrhages at large vessel aneurysms. ECs at leakage hotspots showed induction of caveolae on abluminal surfaces and structural defects including basement membrane thickening and disruption. Our work suggests that capillary pericytes regulate cerebrovascular patterning in development and vSMCs of major arteries protect from hemorrhage and BBB breakdown in older zebrafish. The fact that young zebrafish have a functional BBB in the absence of mural cells calls for renewed interrogation of mural cell control of the BBB throughout vertebrate evolution.

developmental biology↗

bioRxiv2024

Unsaturated lipids as key control points for caveola formation and disassembly

Caveolae are specialized plasma membrane domains with a unique lipid composition. Recent work has implicated lipid peroxidation in triggering caveola disassembly, releasing caveolar proteins to regulate the cellular response to oxidative stress. Here we investigated the role of specific lipid species in caveola formation and response to oxidative stress. Systematic screening of lipid enzymes identified ACSL4, a critical enzyme in the synthesis of polyunsaturated fatty acid-containing lipids, and enzymes involved in the biosynthesis of pro-ferroptotic ether lipids, as key regulators of caveola formation. Omega-6 fatty acids promoted efficient caveola formation, while their oxidation or displacement by omega-3 or monounsaturated fatty acids disrupted this process. Moreover, we found that omega-6 fatty acid-containing membrane lipids were required for oxidative stress-induced caveola disassembly. These findings unveil a new model for caveola formation, highlighting specific unsaturated lipids as essential caveolar components and key control points for caveola disassembly in response to an oxidizing environment.

cell biology↗

bioRxiv2024

A modular encapsulation system for precision delivery of proteins, nucleic acids and therapeutics

Targeted nanoparticles have the potential to revolutionize therapeutics for medical applications. Here, we demonstrate the utility of a flexible precision nanovesicle delivery system for functional delivery of DNA, RNA, proteins and drugs into target cells. Nanovesicles generated by the membrane sculpting protein caveolin, termed caveospheres, can be loaded with RNA, DNA, proteins or drugs post-synthesis or incorporate genetically-encoded cargo proteins during production without the need for protein purification. Functionalized fluorescently-labeled caveospheres form a modular system that shows high stability in biological fluids, specific uptake by target-positive cells, and can deliver proteins, drugs, DNA, and mRNA directly to the cytoplasm and nuclei of only the target cells. The negligible level of off-target transduction and uniform levels of targeted expression demonstrates advantages of the system over lipid-mediated gene delivery. Caveospheres can also be engineered to mimic viral particles by displaying the SARS-CoV-2-RBD protein, enabling targeted delivery to human bronchial epithelial cells. We demonstrate their application as a targeted transfection system for cells in culture, and critically, their efficacy in precision tumor killing in vivo.

bioengineering↗

bioRxiv2024

Mechanism of membrane curvature generation and caveola formation by flat disc-like complexes of caveolin

Membrane sculpting by caveolin and accessory proteins is crucial for caveola formation. The discovery of the disc-like structure of caveolin oligomers has challenged earlier models for membrane shaping by caveolins. The flat shape of the caveolin discs apparently contradicts the large curvature of caveolar membranes these discs generate upon their predicted embedding into the cytoplasmic membrane leaflet. Here we have provided a mechanism for this phenomenon. We proposed that the central factor behind the membrane shaping by caveolin discs is a differential interaction of the membrane lipid monolayers with each other and with the hydrophobic faces of the caveolin discs. Based on this hypothesis we demonstrated by computations that the caveolin disc insertion causes elastic stresses of tilt and splay in the membrane monolayers, which, in turn, drive membrane kinking along the disc boundaries. The resulting membrane shapes are predicted to have a faceted appearance in agreement with observations and the estimated effective curvatures of these shapes are equal to those measured for caveolae in cells. We predicted and analysed the membrane-mediated repulsive forces developing between the inserted caveolin discs and discussed the strength of the counterforces needed to concentrate caveolin discs in the membrane plane. Besides recovering the major features of caveolar formation and morphology, our model provides a new mechanistic understanding of the role of cholesterol and other lipids with similar intrinsic curvature in the caveola assembly and control of caveolar size.

biophysics↗

bioRxiv2023

Flexing fish: cell surface plasticity in response to shape change in the whole organism

Plasma membrane rupture can result in catastrophic cell death. The skeletal muscle fibre plasma membrane, the sarcolemma, provides an extreme example of a membrane subject to mechanical stress since these cells specifically evolved to generate contraction and movement. A quantitative model correlating ultrastructural remodelling of surface architecture with tissue changes in vivo is required to understand how membrane domains contribute to the shape changes associated with tissue deformation in whole animals. We and others have shown that loss of caveolae, small invaginations of the plasma membrane particularly prevalent in the muscle sarcolemma, renders the plasma membrane more susceptible to rupture during stretch1-3. While it is thought that caveolae are able to flatten and be absorbed into the bulk membrane to buffer local membrane expansion, a direct demonstration of this model in vivo has been unachievable since it would require measurement of caveolae at the nanoscale combined with detailed whole animal morphometrics under conditions of perturbation. Here, we describe the development and application of the "active trapping model" where embryonic zebrafish are immobilised in a curved state that mimics natural body axis curvature during an escape response. The model is amenable to multiscale, multimodal imaging including high-resolution whole animal three-dimensional quantitative electron microscopy. Using the active trapping model, we demonstrate the essential role of caveolae in maintaining sarcolemmal integrity and quantify the specific contribution of caveolar-derived membrane to surface expansion. We show that caveolae directly contribute to an increase in plasma membrane surface area under physiologically relevant membrane deformation conditions.

cell biology↗

bioRxiv2023

Caveola mechanotransduction reinforces the cortical cytoskeleton to promote epithelial resistance

As physical barriers, epithelia must preserve their integrity when challenged by mechanical stresses. Cell-cell junctions linked to the cortical cytoskeleton play key roles in this process, often with mechanotransduction mechanisms that reinforce tissues. Caveolae are mechanosensitive organelles that buffer tension via disassembly. Loss of caveolae, through caveolin-1 or cavin1 depletion, causes activation of PtdIns(4, 5)P2 signalling, recruitment of FMNL2 formin, and enhanced cortical actin assembly. How this equates to physiological responses in epithelial cells containing endogenous caveolae is unknown. Here we examined the effect of mechanically-inducing acute disassembly of caveolae in epithelia. We show that perturbation of caveolae, through direct mechanical stress, reinforces the actin cortex at adherens junctions. Increasing interactions with membrane lipids by introducing multiple phosphatidylserine-binding undecad cavin1 (UC1) repeat domains into cavin1 rendered caveolae more stable to mechanical stimuli. This molecular stabilization blocked cortical reinforcement in response to mechanical stress. Cortical reinforcement elicited by the mechanically-induced disassembly of caveolae increased epithelial resilience against tensile stresses. These findings identify the actin cortex as a target of caveola mechanotransduction that contributes to epithelial integrity.

cell biology↗