Biology subjects

Lamaze, C.

Publications and source records attributed to Lamaze, C..

9 recordsLinked to original sources

bioRxiv2026

Mechano-sensitivity of multi-component caveolae

Caveolae are small spherical invaginations of the cell membrane with well established mechano-sensing and mechano-regulation functions. The release of caveolae components upon tension elevation is key to their mechao-signalling function. We present a thermodynamic model of caveolae stability under tension based on the phase separation of membrane-associated proteins into invaginated, multi-component membrane domains enriched in the curvature-generating membrane protein caveolin, and stabilised by the curvature-dependent binding of cytosolic proteins: members of the Cavin family which can form a rigid coat over caveolin domains, and the ATPase EHD2 which can form ring-like oligomers at the caveolae neck. This model shows that purely membrane domains show gradual release of their components upon tension elevation. Invaginations stabilised by a Cavin coat can sustain higher tensions with potentially sharp Cavin unbinding at a threshold tension but still release their membrane components smoothly upon tension increase. On the other hand, caveolae stabilised by an EHD2 ring exhibit increased mechano-protection and allow for a sharp release of membrane components. Therefore, the multi-component nature of caveolae self-organisation bestows these membrane domains with a switch-like response to tension variations which leads to the abrupt release of caveolae content beyond a well defined membrane tension threshold. Significance statementCaveolae are small invaginated domains of Caveolin proteins at the plasma membrane, stabilised by coat of Cavin proteins and a ring of EHD2 proteins at their neck. They contribute to cellular mechano-sensing by disassembling under elevated membrane tension, thereby releasing components that can regulate signalling events. Using a thermodynamic model of protein self-assembly, we show that caveolin domains disassemble smoothly under tension. While the Cavin coat affords mechanical protection without altering this gradual release, the EHD2 ring induces a switch-like release near a threshold tension, enabling acute mechano-sensing.

biophysics↗

bioRxiv2025

Palmitoylated caveolin-1 enables endosome sorting of complex sphingolipids

Complex sphingolipids form in the Golgi apparatus and require transport by vesicular carriers to reach the plasma membrane (PM) where they assemble with cholesterol to affect membrane function. The caveolin proteins have been implicated in sphingolipid trafficking but by mechanisms unknown. Here, we found that cells lacking caveolin-1 (Cav1) distributed the complex sphingolipids to the lysosome rather than to the PM. This was not seen in Cavin-1 KO cells, implicating a function for Cav1 independent of caveolae. The defect in trafficking localized to the sorting endosome where the complex sphingolipids failed to enter recycling tubules serving the PM. Sphingolipid trafficking was rescued by over-expression of Cav1, but not by a Cav1 mutant that lacked the S-palmitoylation sites. Thus, noncaveolar and palmitoylated Cav1 appears to act as a chaperone, or selectivity filter, enabling entry of the complex sphingolipids into endocytic recycling tubules to shape the composition of the PM.

cell biology↗

bioRxiv2024

Caveolin-1 and mechanical stress control the release of a pro-metastatic subpopulation of small extracellular vesicles

Mechanical forces within the tumor microenvironment critically influence cancer progression, in part by modulating extracellular vesicle (EV) dynamics. However, the molecular mechanisms by which EVs respond to mechanical cues remain poorly understood. Here, we identify caveolin-1 (Cav1), a core structural component of caveolae, specialized membrane invaginations that act as mechanosensors, as a key regulator of EV release and composition under mechanical stress. We demonstrate that both 2D osmotic shock and 3D mechanical compression significantly enhance EV secretion from cancer cells in a Cav1-dependent manner. These EVs exhibit a distinct lipid profile and are selectively enriched in proteins involved in cell adhesion, motility, wound healing and extracellular matrix remodeling, cargo that is lost upon Cav1 deletion. Functionally, EVs secreted from mechanically stressed cells preferentially accumulate in the liver in vivo and promote breast cancer cell migration and invasion in vitro, effects abolished in the absence of Cav1. Together, these findings reveal a previously unrecognized role for Cav1 in coupling mechanical stress to EV biogenesis and cargo loading, thereby promoting metastatic traits. This study underscores a novel mechanism by which mechanical cues within tumor environment regulate EV-mediated communication and suggests that Cav1-enriched EVs may contribute to pre-metastatic niche formation.

cancer biology↗

bioRxiv2023

Dia2 formin controls receptor activity by organizing plasma membrane lipid partitioning at the nanoscale

Activation of JAK/STAT signaling by IFN-{gamma} requires partitioning of IFN-{gamma}R into specific lipid nanodomains at the plasma membrane. Using IFN-{gamma}R as a proxy, we investigated the role of actin dynamics in the formation and organization of lipid nanodomains, a process that remains poorly understood. We identified formin Dia2/DIAPH3 as a specific and RhoA -dependent regulator of IFN-{gamma}-induced JAK/STAT signaling. Based on lipidomics and specific probes enabling membrane lipid imaging by super resolution microscopy, we demonstrate that Dia2 is required for proper assembly of sphingomyelin and cholesterol lipid complexes. Finally, we show that the disorganization of lipid nanodomains induced by Dia2 depletion results in drastic changes in nano-partitioning and activity of other membrane proteins, such as Thy1 and PD-L1. Our data establish, therefore, the central role of the RhoA-Dia2 axis in the regulation of IFN-{gamma} induced JAK/STAT signaling, and more broadly, in the nanoscale organization of the plasma membrane.

cell biology↗

bioRxiv2022

Caveolae govern plasma membrane mechanics to protect cells against EDIN B-induced transcellular tunnel formation and lethality from S. aureus septicaemia

Large transcellular pores elicited by bacterial mono-ADP-ribosyltransferase (mART) exotoxins inhibiting the small RhoA GTPase compromise the endothelial barrier. Recent advances in biophysical modeling point towards membrane tension and bending rigidity as the minimal set of mechanical parameters determining the nucleation and maximal size of transendothelial cell macroaperture (TEM) tunnels induced by bacterial RhoA-targeting mART exotoxins. We report that cellular depletion of caveolin-1, the membrane-embedded building block of caveolae, and depletion of cavin-1, the master regulator of caveolae invaginations, increase the number of TEMs per cell. The enhanced occurrence of TEM nucleation events correlates with a reduction of cell height, due to the increase of cell spreading and decrease of cell volume, which, together with the disruption of RhoA-driven F-actin meshwork, favor membrane apposition for TEM nucleation. Strikingly, caveolin-1 specifically controls the opening speed of TEMs leading to their dramatic 5.4-fold larger widening. Consistent with the increase of TEM density and width in siCAV1 cells, we record a higher lethality in caveolin-1-deficient mice subjected to a catalytically active mART exotoxin targeting RhoA during staphylococcal bloodstream infection. Combined theoretical modeling with independent biophysical measurements of plasma membrane bending rigidity point toward a specific contribution of caveolin-1 to membrane stiffening in addition to the role of cavin-1/caveolin-1-dependent caveolae in the control of membrane tension homeostasis.

biophysics↗

bioRxiv2022

Caveolae promote successful abscission by controlling intercellular bridge tension during cytokinesis

During cytokinesis, the intercellular bridge (ICB) connecting the daughter cells experiences pulling forces, which delay abscission by preventing the assembly of the ESCRT scission machinery. Abscission is thus triggered by tension release, but how ICB tension is controlled is unknown. Here, we report that caveolae, which are known to control membrane tension upon mechanical stress in interphase cells, are located at the midbody, at the abscission site and at the ICB/cell interface in dividing cells. Functionally, the loss of caveolae delays ESCRT-III recruitment during cytokinesis and impairs abscission. This is the consequence of a 2-fold increase of ICB tension measured by laser ablation, associated with a local increase in myosin II activity at the ICB/cell interface. We thus propose that caveolae buffer membrane tension and limit contractibility at the ICB to promote ESCRT-III assembly and cytokinetic abscission. Altogether, this work reveals an unexpected connection between caveolae and the ESCRT machinery and the first role of caveolae in cell division. TEASERCaveolae limit the tension in the intercellular bridge during cytokinesis to enable ESCRT-III assembly and successful abscission.

cell biology↗

bioRxiv2019

Caveolae coupling of melanocytes signaling and mechanics is required for human skin pigmentation

Tissue homeostasis requires regulation of cell-cell communication, which relies on signaling molecules and cell contacts. In skin epidermis, keratinocytes secrete specific factors transduced by melanocytes into signaling cues to promote their pigmentation and dendrite outgrowth, while melanocytes transfer melanin pigments to keratinocytes to convey skin photoprotection. How epidermal cells integrate these functions remains poorly characterized. Here, we found that caveolae polarize in melanocytes and are particularly abundant at melanocyte-keratinocyte interface. Caveolae in melanocytes are sensitive to ultra-violet radiations and miRNAs released by keratinocytes. Preventing caveolae formation in melanocytes results in increased production of intracellular cAMP and melanin pigments, but decreases cell protrusions, cell-cell contacts, pigment transfer and epidermis pigmentation. Altogether, our data establish that, in melanocytes, caveolae serve as key molecular hubs that couple signaling outputs from keratinocytes to mechanical plasticity. This process is crucial to maintain cell-cell contacts and intercellular communication, skin pigmentation and tissue homeostasis.

cell biology↗

bioRxiv2019

STAM Interaction with Hrs Controls JAK/STAT Activation by Interferon-α at the Early Endosome

Activation of the Janus kinase (JAK)/signal transducer and activator of transcription (STAT) pathway by type I interferons (IFN) requires clathrin-dependent endocytosis of the IFN-/{beta} receptor (IFNAR). The molecular machinery that brings about the selective activation of IFN-/{beta}-induced JAK/STAT signaling on endosomes remains unknown. Here we show that the constitutive association of STAM with IFNAR1 and the TYK2 Janus kinase at the plasma membrane prevents the activation of TYK2 by type I IFNs. IFN- stimulated endocytosis leads to the interaction of IFNAR1 with Hrs on early endosomes, which then relieves TYK2 inhibition by STAM and thereby allows for TYK2 and IFNAR signaling. In contrast, IFN-{beta} stimulation results in sorting of IFNAR to a distinct endosomal subdomain where the receptor is activated independently from Hrs. Our results identify the molecular machinery that controls the spatiotemporal activation of TYK2 and establish the central role of endosomal sorting in the differential regulation of JAK/STAT signaling by IFN- and IFN-{beta}.\n\nSummaryThe spatiotemporal activation of JAK/STAT signaling by IFN- is controlled by STAM association with Hrs at the early endosome.

cell biology↗

bioRxiv2018

Lack of functional caveolae in Cav3 mutated human dystrophic myotubes results in deficient mechanoprotection and IL6/STAT3 mechanosignaling.

Caveolin-3 is the major structural protein of caveolae in muscle cells. Mutations in the CAV3 gene cause different type of muscle disorders mostly characterized by defects in membrane integrity and repair, deregulation in the expression of various muscle proteins and deregulation of several muscle associated signaling pathways. We show here that myotubes derived from patients bearing the CAV3 P28L and R26Q mutations present a lack of functional caveolae at the plasma membrane which results in an abnormal mechanoresponse. Mutant myotubes can no longer buffer the increase of membrane tension induced by mechanical stress and present an hyperactivation of the IL6/STAT3 signaling pathway at rest and under mechanical stress. The impaired mechanical regulation of the IL6/STAT3 signaling pathway by caveolae leads to chronic activation and a higher expression of muscle specific genes. These defects could be reversed by reassembling a pool of functional caveolae through expression of wild type Cav3. Our findings bring more mechanistic insight into human Cav3 associated muscle disorders and show a general defect in the mechanoresponse of CAV3 P28L and R26Q myotubes.

cell biology↗