The Experts below are selected from a list of 12654 Experts worldwide ranked by ideXlab platform
Robert G. Parton - One of the best experts on this subject based on the ideXlab platform.
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a role for caveola forming proteins caveolin 1 and cavin1 in the pro invasive response of glioblastoma to osmotic and hydrostatic pressure
Journal of Cellular and Molecular Medicine, 2020Co-Authors: Jiawen Qiu, Charles Ferguson, Robert G. Parton, Kerrie-ann Mcmahon, Zeyad D. Nassar, Gregory J Riggins, Jonathan M Harris, P N Shaw, Marie-odile ParatAbstract:In solid tumours, elevated interstitial fluid pressure (osmotic and hydrostatic pressure) is a barrier to drug delivery and correlates with poor prognosis. Glioblastoma (GBM) further experience compressive force when growing within a space limited by the skull. Caveolae are proposed to play mechanosensing roles, and caveola-forming proteins are overexpressed in GBM. We asked whether Caveolae mediate the GBM response to osmotic pressure. We evaluated in vitro the influence of spontaneous or experimental down-regulation of caveola-forming proteins (caveolin-1, CAVIN1) on the proteolytic profile and invasiveness of GBM cells in response to osmotic pressure. In response to osmotic pressure, GBM cell lines expressing caveola-forming proteins up-regulated plasminogen activator (uPA) and/or matrix metalloproteinases (MMPs), some EMT markers and increased their in vitro invasion potential. Down-regulation of caveola-forming proteins impaired this response and prevented hyperosmolarity-induced mRNA expression of the water channel aquaporin 1. CRISPR ablation of caveola-forming proteins further lowered expression of matrix proteases and EMT markers in response to hydrostatic pressure, as a model of mechanical force. GBM respond to pressure by increasing matrix-degrading enzyme production, mesenchymal phenotype and invasion. Caveola-forming proteins mediate, at least in part, the pro-invasive response of GBM to pressure. This may represent a novel target in GBM treatment.
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cavin1 intrinsically disordered domains are essential for fuzzy electrostatic interactions and caveola formation
bioRxiv, 2019Co-Authors: Vikas A Tillu, Robert G. Parton, Kerrie-ann Mcmahon, Matthias Floetenmeyer, Nicholas Ariotti, James Rae, Oleksiy Kovtun, Ya Gao, Brett M CollinsAbstract:Caveolae are spherical-structured nanodomains of the plasma membrane, generated by cooperative assembly of caveolin and cavin proteins. Cavins are cytosolic peripheral membrane proteins with negatively charged intrinsically disordered regions (DR1-3) that flank positively charged alpha-helical regions (HR1 and HR2). Here we show that the three DR domains of Cavin1 are essential for caveola formation and dynamic trafficking of Caveolae. Electrostatic interactions between DR and HR regions promote liquid-liquid phase separation behaviour of Cavin1, assembly of Cavin1 polymers in solution, generation of membrane curvature in a reconstituted system, and Cavin1 recruitment to Caveolae in cells. Removal of the first disordered region causes irreversible gel formation in vitro and results in aberrant caveola trafficking through the endosomal system. We propose a model for caveola assembly whereby fuzzy electrostatic interactions between Cavin1 proteins, combined with CAV1 and membrane lipid interactions, are required to generate membrane curvature and a metastable caveola coat.
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correlation of the invasive potential of glioblastoma and expression of caveola forming proteins caveolin 1 and cavin1
Journal of Neuro-oncology, 2019Co-Authors: Zeyad D. Nassar, Robert G. Parton, Kerrie-ann Mcmahon, Samira Khabbazi, Nan Xie, Gregory J Riggins, Jonathan M Harris, Marie-odile ParatAbstract:Glioblastoma (GBM) is the most common primary brain cancer. The average survival time for the majority of patients is approximately 15 months after diagnosis. A major feature of GBM that contributes to its poor prognosis is its high invasiveness. Caveolae are plasma membrane subdomains that participate in numerous biological functions. Caveolin-1 and Caveolae Associated Protein 1 (CAVIN1), formerly termed Polymerase I and Transcript Release Factor, are both necessary for caveola formation. We hypothesized that high expression of caveola-forming proteins in GBM promotes invasiveness via modulation of the production of matrix-degrading enzymes. The mRNA expression of caveola-forming proteins and matrix proteases in GBM samples, and survival after stratifying patients according to caveolin-1 or CAVIN1 expression, were analyzed from TCGA and REMBRANDT databases. The proteolytic profile of cell lines expressing or devoid of caveola-forming proteins was investigated using zymography and real-time qPCR. Invasion through basement membrane-like protein was investigated in vitro. Expression of both caveolin-1 and CAVIN1 was increased in GBM compared to normal samples and correlated with expression of urokinase plasminogen activator (uPA) and gelatinases. High expression of caveola-forming proteins was associated with shorter survival time. GBM cell lines capable of forming Caveolae expressed more uPA and matrix metalloproteinase-2 (MMP-2) and/or -9 (MMP-9) and were more invasive than GBM cells devoid of caveola-forming proteins. Experimental manipulation of caveolin-1 or CAVIN1 expression in GBM cells recapitulated some, but not all of these features. Caveolae modulate GBM cell invasion in part via matrix protease expression.
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Caveolae Protect Notochord Cells against Catastrophic Mechanical Failure during Development
Current Biology, 2017Co-Authors: Harriet P. Lo, Nick Martel, Charles Ferguson, Guillermo A. Gomez, Thomas E. Hall, Jean Giacomotto, Robert G. PartonAbstract:Summary The embryonic notochord is a flexible structure present during development that serves as scaffold for formation of the vertebrate spine. This rod-like organ is thought to have evolved in non-vertebrate chordates to facilitate locomotion by providing a rigid but flexible midline structure against which the axial muscles can contract. This hydrostatic "skeleton" is exposed to a variety of mechanical forces during oscillation of the body. There is evidence that Caveolae, submicroscopic cup-shaped plasma membrane pits, can buffer tension in cells that undergo high levels of mechanical stress. Indeed, Caveolae are particularly abundant in the embryonic notochord. In this study, we used the CRISPR/Cas9 system to generate a mutant zebrafish line lacking Cavin1b, a coat protein required for caveola formation. Our cavin1b −/− zebrafish line exhibits reduced locomotor capacity and prominent notochord lesions characterized by necrotic, damaged, and membrane-permeable cells. Notochord diameter and body length are reduced, but remarkably, the mutants recover and are homozygous viable. By manipulating mechanical stress using a number of different assays, we show that progression of lesion severity in the mutant notochord is directly dependent on locomotion. We also demonstrate changes in caveola morphology in vivo in response to mechanical stress. Finally, induction of a catastrophic collapse of live cavin1b −/− mutant notochord cells provides the first real-time observation of Caveolae mediating cellular mechanoprotection.
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Regulate Clathrin-Independent Endocytosis
2016Co-Authors: See Profile, Guillermo A. Gomez, Robert G. Parton, Natasha Chaudhary, Mark T. Howes, Kerrie-ann Mcmahon, Nicole L. SchieberAbstract:Several studies have suggested crosstalk between different clathrin-independent endocytic pathways. However, the molecular mechanisms and functional relevance of these interactions are unclear. Caveolins and cavins are crucial components of Caveolae, specialized microdomains that also constitute an endocytic route. Here we show that specific caveolar proteins are independently acting negative regulators of clathrin-independent endocytosis. Cavin-1 and Cavin-3, but not Cavin-2 or Cavin-4, are potent inhibitors of the clathrin-independent carriers/GPI-AP enriched early endosomal compartment (CLIC/GEEC) endocytic pathway, in a process independent of caveola formation. Caveolin-1 (CAV1) and CAV3 also inhibit the CLIC/GEEC pathway upon over-expression. Expression of caveolar protein leads to reduction in formation of early CLIC/GEEC carriers, as detected by quantitative electron microscopy analysis. Furthermore, the CLIC/GEEC pathway i
Marie-odile Parat - One of the best experts on this subject based on the ideXlab platform.
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Caveola-forming proteins and prostate cancer
Cancer and Metastasis Reviews, 2020Co-Authors: Zeyad D. Nassar, Marie-odile ParatAbstract:Caveolae are specialised and dynamic plasma membrane subdomains, involved in many cellular functions including endocytosis, signal transduction, mechanosensing and lipid storage, trafficking, and metabolism. Two protein families are indispensable for caveola formation and function, namely caveolins and cavins. Mutations of genes encoding these caveolar proteins cause serious pathological conditions such as cardiomyopathies, skeletal muscle diseases, and lipodystrophies. Deregulation of caveola-forming protein expression is associated with many types of cancers including prostate cancer. The distinct function of secretion of the prostatic fluid, and the unique metabolic phenotype of prostate cells relying on lipid metabolism as a main bioenergetic pathway further suggest a significant role of Caveolae and caveolar proteins in prostate malignancy. Accumulating in vitro , in vivo , and clinical evidence showed the association of caveolin-1 with prostate cancer grade, stage, metastasis, and drug resistance. In contrast, cavin-1 was found to exhibit tumour suppressive roles. Studies on prostate cancer were the first to show the distinct function of the caveolar proteins depending on their localisation within the caveolar compartment or as cytoplasmic or secreted proteins. In this review, we summarise the roles of caveola-forming proteins in prostate cancer and the potential of exploiting them as therapeutic targets or biological markers.
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a role for caveola forming proteins caveolin 1 and cavin1 in the pro invasive response of glioblastoma to osmotic and hydrostatic pressure
Journal of Cellular and Molecular Medicine, 2020Co-Authors: Jiawen Qiu, Charles Ferguson, Robert G. Parton, Kerrie-ann Mcmahon, Zeyad D. Nassar, Gregory J Riggins, Jonathan M Harris, P N Shaw, Marie-odile ParatAbstract:In solid tumours, elevated interstitial fluid pressure (osmotic and hydrostatic pressure) is a barrier to drug delivery and correlates with poor prognosis. Glioblastoma (GBM) further experience compressive force when growing within a space limited by the skull. Caveolae are proposed to play mechanosensing roles, and caveola-forming proteins are overexpressed in GBM. We asked whether Caveolae mediate the GBM response to osmotic pressure. We evaluated in vitro the influence of spontaneous or experimental down-regulation of caveola-forming proteins (caveolin-1, CAVIN1) on the proteolytic profile and invasiveness of GBM cells in response to osmotic pressure. In response to osmotic pressure, GBM cell lines expressing caveola-forming proteins up-regulated plasminogen activator (uPA) and/or matrix metalloproteinases (MMPs), some EMT markers and increased their in vitro invasion potential. Down-regulation of caveola-forming proteins impaired this response and prevented hyperosmolarity-induced mRNA expression of the water channel aquaporin 1. CRISPR ablation of caveola-forming proteins further lowered expression of matrix proteases and EMT markers in response to hydrostatic pressure, as a model of mechanical force. GBM respond to pressure by increasing matrix-degrading enzyme production, mesenchymal phenotype and invasion. Caveola-forming proteins mediate, at least in part, the pro-invasive response of GBM to pressure. This may represent a novel target in GBM treatment.
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correlation of the invasive potential of glioblastoma and expression of caveola forming proteins caveolin 1 and cavin1
Journal of Neuro-oncology, 2019Co-Authors: Zeyad D. Nassar, Robert G. Parton, Kerrie-ann Mcmahon, Samira Khabbazi, Nan Xie, Gregory J Riggins, Jonathan M Harris, Marie-odile ParatAbstract:Glioblastoma (GBM) is the most common primary brain cancer. The average survival time for the majority of patients is approximately 15 months after diagnosis. A major feature of GBM that contributes to its poor prognosis is its high invasiveness. Caveolae are plasma membrane subdomains that participate in numerous biological functions. Caveolin-1 and Caveolae Associated Protein 1 (CAVIN1), formerly termed Polymerase I and Transcript Release Factor, are both necessary for caveola formation. We hypothesized that high expression of caveola-forming proteins in GBM promotes invasiveness via modulation of the production of matrix-degrading enzymes. The mRNA expression of caveola-forming proteins and matrix proteases in GBM samples, and survival after stratifying patients according to caveolin-1 or CAVIN1 expression, were analyzed from TCGA and REMBRANDT databases. The proteolytic profile of cell lines expressing or devoid of caveola-forming proteins was investigated using zymography and real-time qPCR. Invasion through basement membrane-like protein was investigated in vitro. Expression of both caveolin-1 and CAVIN1 was increased in GBM compared to normal samples and correlated with expression of urokinase plasminogen activator (uPA) and gelatinases. High expression of caveola-forming proteins was associated with shorter survival time. GBM cell lines capable of forming Caveolae expressed more uPA and matrix metalloproteinase-2 (MMP-2) and/or -9 (MMP-9) and were more invasive than GBM cells devoid of caveola-forming proteins. Experimental manipulation of caveolin-1 or CAVIN1 expression in GBM cells recapitulated some, but not all of these features. Caveolae modulate GBM cell invasion in part via matrix protease expression.
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Molecular Determinants of the Cellular Entry of Asymmetric Peptide Dendrimers and Role of Caveolae
2016Co-Authors: Prarthana V. Rewatkar, Harendra S. Parekh, Marie-odile ParatAbstract:Caveolae are flask-shaped plasma membrane subdomains abundant in most cell types that participate in endocytosis. Caveola formation and functions require membrane proteins of the caveolin family, and cytoplasmic proteins of the cavin family. Cationic peptide dendrimers are non-vesicular chemical carriers that can transport pharmacological agents or genetic material across the plasma membrane. We prepared a panel of cationic dendrimers and investigated whether they require Caveolae to enter into cells. Cell-based studies were performed using wild type or caveola-deficient i.e. caveolin-1 or PTRF gene-disrupted cells. There was a statistically significant difference in entry of cationic dendrimers between wild type and caveola-deficient cells. We further unveiled differences between dendrimers with varying charge density and head groups. Our results show, using a molecular approach, that (i) expression of caveola-forming proteins promotes cellular entry of cationic dendrimers and (ii) dendrimer structure can be modified to promote endocytosis in caveola-forming cells.
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Express in Vitro Plasmid Transfection Achieved with 16+ Asymmetric Peptide Dendrimers
2016Co-Authors: Prarthana V. Rewatkar, Harendra S. Parekh, David P. Sester, Marie-odile ParatAbstract:Asymmetric cationic amino acid-based dendrimers are highly branched chemically derived gene vectors developed to transport cargo such as plasmid DNA across the plasma membrane. We have previously demonstrated their propensity to enter cells that form Caveolae, driven by positive charge density and promoted by arginine head groups. Caveolae are plasma membrane subdomains serving a number of cellular functions including endocytosis. Their formation requires membrane proteins (caveolins) and cytoplasmic proteins (cavins), so that gene disruption of either caveolin-1 or cavin-1 (also known as PTRF, i.e., polymerase I and transcript release factor) results in caveola deficiency. Here we evaluated the ability of a 16+ charged asymmetric arginine dendrimer to transfect plasmid DNA into cultured cells. We unveiled efficient transfection efficiencies (≥30%) 24–48 h after exposing the cells to dendrimer/pDNA complexes for only 5 min. Using wild type (WT) and caveolin-1 or PTRF gene-disrupted, i.e., caveola-deficient mouse embryo fibroblasts, we further show that Caveolae promote pDNA transfection by 16+ charged asymmetric arginine dendrimers
Michelle M. Hill - One of the best experts on this subject based on the ideXlab platform.
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Endocytic Crosstalk: Cavins, Caveolins, and Caveolae Regulate Clathrin-Independent Endocytosis
2016Co-Authors: Natasha Chaudhary, Guillermo A. Gomez, Mark T. Howes, Kerrie-ann Mcmahon, James A. Rae, Nicole L. Schieber, Michelle M. Hill, Katharina Gaus, Alpha S. YapAbstract:Several studies have suggested crosstalk between different clathrin-independent endocytic pathways. However, the molecular mechanisms and functional relevance of these interactions are unclear. Caveolins and cavins are crucial components of Caveolae, specialized microdomains that also constitute an endocytic route. Here we show that specific caveolar proteins are independently acting negative regulators of clathrin-independent endocytosis. Cavin-1 and Cavin-3, but not Cavin-2 or Cavin-4, are potent inhibitors of the clathrin-independent carriers/GPI-AP enriched early endosomal compartment (CLIC/GEEC) endocytic pathway, in a process independent of caveola formation. Caveolin-1 (CAV1) and CAV3 also inhibit the CLIC/GEEC pathway upon over-expression. Expression of caveolar protein leads to reduction in formation of early CLIC/GEEC carriers, as detected by quantitative electron microscopy analysis. Furthermore, the CLIC/GEEC pathway is upregulated in cells lacking CAV1/Cavin-1 or with reduced expression of Cavin-1 and Cavin-3. Inhibition by caveolins can be mimicked by the isolated caveolin scaffolding domain and is associated with perturbed diffusion of lipid microdomain components, as revealed by fluorescence recovery after photobleaching (FRAP) studies. In the absence of cavins (and Caveolae) CAV1 is itself endocytosed preferentially through the CLIC/GEEC pathway, but the pathway loses polarization and sorting attributes with consequences for membrane dynamics and endocytic polarization in migrating cells and adult muscle tissue. We also found that noncaveolar Cavin-1 can act as a modulator for the activity of the key regulator of th
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molecular characterization of caveolin induced membrane curvature
Journal of Biological Chemistry, 2015Co-Authors: Nicholas Ariotti, Charles Ferguson, Michelle M. Hill, Natalya Leneva, Piers J Walser, James Rae, Dorothy Loo, Satomi Okano, Brett M Collins, Robert G. PartonAbstract:The generation of Caveolae involves insertion of the cholesterol-binding integral membrane protein caveolin-1 (Cav1) into the membrane, however, the precise molecular mechanisms are as yet unknown. We have speculated that insertion of the caveolin scaffolding domain (CSD), a conserved amphipathic region implicated in interactions with signaling proteins, is crucial for caveola formation. We now define the core membrane-juxtaposed region of Cav1 and show that the oligomerization domain and CSD are protected by tight association with the membrane in both mature mammalian Caveolae and a model prokaryotic system for caveola biogenesis. Cryoelectron tomography reveals the core membrane-juxtaposed domain to be sufficient to maintain oligomerization as defined by polyhedral distortion of the caveolar membrane. Through mutagenesis we demonstrate the importance of the membrane association of the oligomerization domain/CSD for defined caveola biogenesis and furthermore, highlight the functional significance of the intramembrane domain and the CSD for defined caveolin-induced membrane deformation. Finally, we define the core structural domain of Cav1, constituting only 66 amino acids and of great potential to nanoengineering applications, which is required for caveolin-induced vesicle formation in a bacterial system. These results have significant implications for understanding the role of Cav1 in caveola formation and in regulating cellular signaling events.
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caveola forming proteins caveolin 1 and ptrf in prostate cancer
Nature Reviews Urology, 2013Co-Authors: Zeyad D. Nassar, Robert G. Parton, Michelle M. Hill, Marie-odile ParatAbstract:The expression of caveola-forming proteins is dysregulated in prostate cancer. Caveolae are flask-shaped invaginations of the plasma membrane that have roles in membrane trafficking and cell signalling. Members of two families of proteins--caveolins and cavins--are known to be required for the formation and functions of Caveolae. Caveolin-1, the major structural protein of Caveolae, is overexpresssed in prostate cancer and has been demonstrated to be involved in prostate cancer angiogenesis, growth and metastasis. Polymerase I and transcript release factor (PTRF) is the only cavin family member necessary for caveola formation. When exogenously expressed in prostate cancer cells, PTRF reduces aggressive potential, probably via both caveola-mediated and caveola-independent mechanisms. In addition, stromal PTRF expression decreases with progression of the disease. Evaluation of caveolin-1 antibodies in the clinical setting is underway and it is hoped that future studies will reveal the mechanisms of PTRF action, allowing its targeting for therapeutic purposes.
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ptrf cavin 1 expression decreases the migration of pc3 prostate cancer cells role of matrix metalloprotease 9
European Journal of Cell Biology, 2011Co-Authors: C S Aung, Robert G. Parton, Michelle M. Hill, Michele Bastiani, Marie-odile ParatAbstract:Caveolae are specialized plasma membrane subdomains with a distinct lipid and protein composition, which play an essential role in cell physiology by performing trafficking and signalling functions. The structure and functions of Caveolae have been shown to require caveolin-1, a major protein component of Caveolae. Caveolin-1 expression and secretion are increased in metastatic prostate cancer, and caveolin-1 seems to contribute to prostate cancer growth and metastasis. Recently, a cytoplasmic protein named PTRF (Polymerase I and Transcript Release Factor) or cavin-1 was found to be required, in concert with caveolin-1, for the formation and functions of Caveolae. Genetic ablation of PTRF results in loss of Caveolae while caveolin-1 is still expressed, albeit at reduced level, but associates with flat plasma membrane. In metastatic PC3 prostate cancer cells that express abundant caveolin-1 but no PTRF, heterologous PTRF expression restores caveola formation and caveolin-1 distribution (Hill et al., 2008; Cell 132, 113-124). We now show that PTRF/cavin-1 -expressing PC3 cells exhibit decreased migration, and that this effect is mediated by reduced MMP9 production. PTRF/cavin-1, and to a lesser extent, cavin-2, -3, and -4 all decreased MMP9. We further show that the PTRF/cavin-1 -mediated reduction of MMP9 production is independent of caveola formation. Taken together, our results suggest that PTRF/cavin-1 expression alters prostate cancer aggressiveness. (C) 2010 Elsevier GmbH. All rights reserved.
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evolutionary analysis and molecular dissection of caveola biogenesis
Journal of Cell Science, 2008Co-Authors: Matthew Kirkham, Charles Ferguson, Mark T. Howes, Michelle M. Hill, Susan J Nixon, Manuel A Fernandezrojo, Michael Hanzalbayer, Laurent Abirached, Diane E Wakeham, Deborah A BrownAbstract:Caveolae are an abundant feature of mammalian cells. Integral membrane proteins called caveolins drive the formation of Caveolae but the precise mechanisms underlying caveola formation, and the origin of Caveolae and caveolins during evolution, are unknown.
Benjamin J Nichols - One of the best experts on this subject based on the ideXlab platform.
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Caveolae protect endothelial cells from membrane rupture during increased cardiac output
Journal of Cell Biology, 2015Co-Authors: Jade Px Cheng, Carolina Mendozatopaz, Gillian Howard, Jessica Chadwick, Elena Shvets, Andrew S Cowburn, Benjamin J Dunmore, Alexi Crosby, Nicholas W Morrell, Benjamin J NicholsAbstract:Caveolae are strikingly abundant in endothelial cells, yet the physiological functions of Caveolae in endothelium and other tissues remain incompletely understood. Previous studies suggest a mechanoprotective role, but whether this is relevant under the mechanical forces experienced by endothelial cells in vivo is unclear. In this study we have sought to determine whether endothelial Caveolae disassemble under increased hemodynamic forces, and whether Caveolae help prevent acute rupture of the plasma membrane under these conditions. Experiments in cultured cells established biochemical assays for disassembly of caveolar protein complexes, and assays for acute loss of plasma membrane integrity. In vivo, we demonstrate that Caveolae in endothelial cells of the lung and cardiac muscle disassemble in response to acute increases in cardiac output. Electron microscopy and two-photon imaging reveal that the plasma membrane of microvascular endothelial cells in caveolin 1−/− mice is much more susceptible to acute rupture when cardiac output is increased. These data imply that mechanoprotection through disassembly of Caveolae is important for endothelial function in vivo.
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dynamic Caveolae exclude bulk membrane proteins and are required for sorting of excess glycosphingolipids
Nature Communications, 2015Co-Authors: Elena Shvets, Gillian Howard, Vassilis Bitsikas, Carsten G Hansen, Benjamin J NicholsAbstract:Caveolae have long been implicated in endocytosis. Recent data question this link, and in the absence of specific cargoes the potential cellular function of caveolar endocytosis remains unclear. Here we develop new tools, including doubly genome-edited cell lines, to assay the subcellular dynamics of Caveolae using tagged proteins expressed at endogenous levels. We find that around 5% of the cellular pool of Caveolae is present on dynamic endosomes, and is delivered to endosomes in a clathrin-independent manner. Furthermore, we show that Caveolae are indeed likely to bud directly from the plasma membrane. Using a genetically encoded tag for electron microscopy and ratiometric light microscopy, we go on to show that bulk membrane proteins are depleted within Caveolae. Although Caveolae are likely to account for only a small proportion of total endocytosis, cells lacking Caveolae show fundamentally altered patterns of membrane traffic when loaded with excess glycosphingolipid. Altogether, these observations support the hypothesis that caveolar endocytosis is specialized for transport of membrane lipid.
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news from the caves update on the structure and function of Caveolae
Current Opinion in Cell Biology, 2014Co-Authors: Elena Shvets, Benjamin J NicholsAbstract:Recent data from the study of the cell biology of Caveolae have provided insights both into how these flask-shaped invaginations of the plasma membrane are formed and how they may function in different contexts. This review discusses experiments that analyse the composition and ultrastructural distribution of protein complexes responsible for generating Caveolae, that suggest functions for Caveolae in response to mechanical stress or damage to the plasma membrane, that show that Caveolae may have an important role during the signalling events for regulation of metabolism, and that imply that Caveolae can act as endocytic vesicles at the plasma membrane. We also highlight unexpected roles for caveolar proteins in regulating circadian rhythms and new insights into the way in which Caveolae may be involved in fatty acid uptake in the intestine. Current outstanding questions in the field are emphasised.
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molecular composition and ultrastructure of the caveolar coat complex
PLOS Biology, 2013Co-Authors: Gillian Howard, Carolina Mendozatopaz, Sara Sandin, Mark H. Ellisman, Thomas J Deerinck, Mason R Mackey, Benjamin J NicholsAbstract:Caveolae are an abundant feature of the plasma membrane of many mammalian cell types, and have key roles in mechano-transduction, metabolic regulation, and vascular permeability. Caveolin and cavin proteins, as well as EHD2 and pacsin 2, are all present in Caveolae. How these proteins assemble to form a protein interaction network for caveolar morphogenesis is not known. Using in vivo crosslinking, velocity gradient centrifugation, immuno-isolation, and tandem mass spectrometry, we determine that cavins and caveolins assemble into a homogenous 80S complex, which we term the caveolar coat complex. There are no further abundant components within this complex, and the complex excludes EHD2 and pacsin 2. Cavin 1 forms trimers and interacts with caveolin 1 with a molar ratio of about 1∶4. Cavins 2 and 3 compete for binding sites within the overall coat complex, and form distinct subcomplexes with cavin 1. The core interactions between caveolin 1 and cavin 1 are independent of cavin 2, cavin 3, and EHD2 expression, and the cavins themselves can still interact in the absence of caveolin 1. Using immuno-electron microscopy as well as a recently developed protein tag for electron microscopy (MiniSOG), we demonstrate that caveolar coat complexes form a distinct coat all around the caveolar bulb. In contrast, and consistent with our biochemical data, EHD2 defines a different domain at the caveolar neck. 3D electron tomograms of the caveolar coat, labeled using cavin-MiniSOG, show that the caveolar coat is composed of repeating units of a unitary caveolar coat complex.
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sdpr induces membrane curvature and functions in the formation of Caveolae
Nature Cell Biology, 2009Co-Authors: Carsten G Hansen, Gillian Howard, Nicholas A Bright, Benjamin J NicholsAbstract:Caveolae are plasma membrane invaginations with a characteristic flask-shaped morphology. They function in diverse cellular processes, including endocytosis. The mechanism by which Caveolae are generated is not fully understood, but both caveolin proteins and PTRF (polymerase I and transcript release factor, also known as cavin) are important. Here we show that loss of SDPR (serum deprivation protein response) causes loss of Caveolae. SDPR binds directly to PTRF and recruits PTRF to caveolar membranes. Overexpression of SDPR, unlike PTRF, induces deformation of Caveolae and extensive tubulation of the plasma membrane. The B-subunit of Shiga toxin (STB) also induces membrane tubulation and these membrane tubes also originate from Caveolae. STB colocalizes extensively with both SDPR and caveolin 1. Loss of Caveolae reduces the propensity of STB to induce membrane tubulation. We conclude that SDPR is a membrane-curvature-inducing component of Caveolae, and that STB-induced membrane tubulation is facilitated by Caveolae.
Kerrie-ann Mcmahon - One of the best experts on this subject based on the ideXlab platform.
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a role for caveola forming proteins caveolin 1 and cavin1 in the pro invasive response of glioblastoma to osmotic and hydrostatic pressure
Journal of Cellular and Molecular Medicine, 2020Co-Authors: Jiawen Qiu, Charles Ferguson, Robert G. Parton, Kerrie-ann Mcmahon, Zeyad D. Nassar, Gregory J Riggins, Jonathan M Harris, P N Shaw, Marie-odile ParatAbstract:In solid tumours, elevated interstitial fluid pressure (osmotic and hydrostatic pressure) is a barrier to drug delivery and correlates with poor prognosis. Glioblastoma (GBM) further experience compressive force when growing within a space limited by the skull. Caveolae are proposed to play mechanosensing roles, and caveola-forming proteins are overexpressed in GBM. We asked whether Caveolae mediate the GBM response to osmotic pressure. We evaluated in vitro the influence of spontaneous or experimental down-regulation of caveola-forming proteins (caveolin-1, CAVIN1) on the proteolytic profile and invasiveness of GBM cells in response to osmotic pressure. In response to osmotic pressure, GBM cell lines expressing caveola-forming proteins up-regulated plasminogen activator (uPA) and/or matrix metalloproteinases (MMPs), some EMT markers and increased their in vitro invasion potential. Down-regulation of caveola-forming proteins impaired this response and prevented hyperosmolarity-induced mRNA expression of the water channel aquaporin 1. CRISPR ablation of caveola-forming proteins further lowered expression of matrix proteases and EMT markers in response to hydrostatic pressure, as a model of mechanical force. GBM respond to pressure by increasing matrix-degrading enzyme production, mesenchymal phenotype and invasion. Caveola-forming proteins mediate, at least in part, the pro-invasive response of GBM to pressure. This may represent a novel target in GBM treatment.
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cavin1 intrinsically disordered domains are essential for fuzzy electrostatic interactions and caveola formation
bioRxiv, 2019Co-Authors: Vikas A Tillu, Robert G. Parton, Kerrie-ann Mcmahon, Matthias Floetenmeyer, Nicholas Ariotti, James Rae, Oleksiy Kovtun, Ya Gao, Brett M CollinsAbstract:Caveolae are spherical-structured nanodomains of the plasma membrane, generated by cooperative assembly of caveolin and cavin proteins. Cavins are cytosolic peripheral membrane proteins with negatively charged intrinsically disordered regions (DR1-3) that flank positively charged alpha-helical regions (HR1 and HR2). Here we show that the three DR domains of Cavin1 are essential for caveola formation and dynamic trafficking of Caveolae. Electrostatic interactions between DR and HR regions promote liquid-liquid phase separation behaviour of Cavin1, assembly of Cavin1 polymers in solution, generation of membrane curvature in a reconstituted system, and Cavin1 recruitment to Caveolae in cells. Removal of the first disordered region causes irreversible gel formation in vitro and results in aberrant caveola trafficking through the endosomal system. We propose a model for caveola assembly whereby fuzzy electrostatic interactions between Cavin1 proteins, combined with CAV1 and membrane lipid interactions, are required to generate membrane curvature and a metastable caveola coat.
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correlation of the invasive potential of glioblastoma and expression of caveola forming proteins caveolin 1 and cavin1
Journal of Neuro-oncology, 2019Co-Authors: Zeyad D. Nassar, Robert G. Parton, Kerrie-ann Mcmahon, Samira Khabbazi, Nan Xie, Gregory J Riggins, Jonathan M Harris, Marie-odile ParatAbstract:Glioblastoma (GBM) is the most common primary brain cancer. The average survival time for the majority of patients is approximately 15 months after diagnosis. A major feature of GBM that contributes to its poor prognosis is its high invasiveness. Caveolae are plasma membrane subdomains that participate in numerous biological functions. Caveolin-1 and Caveolae Associated Protein 1 (CAVIN1), formerly termed Polymerase I and Transcript Release Factor, are both necessary for caveola formation. We hypothesized that high expression of caveola-forming proteins in GBM promotes invasiveness via modulation of the production of matrix-degrading enzymes. The mRNA expression of caveola-forming proteins and matrix proteases in GBM samples, and survival after stratifying patients according to caveolin-1 or CAVIN1 expression, were analyzed from TCGA and REMBRANDT databases. The proteolytic profile of cell lines expressing or devoid of caveola-forming proteins was investigated using zymography and real-time qPCR. Invasion through basement membrane-like protein was investigated in vitro. Expression of both caveolin-1 and CAVIN1 was increased in GBM compared to normal samples and correlated with expression of urokinase plasminogen activator (uPA) and gelatinases. High expression of caveola-forming proteins was associated with shorter survival time. GBM cell lines capable of forming Caveolae expressed more uPA and matrix metalloproteinase-2 (MMP-2) and/or -9 (MMP-9) and were more invasive than GBM cells devoid of caveola-forming proteins. Experimental manipulation of caveolin-1 or CAVIN1 expression in GBM cells recapitulated some, but not all of these features. Caveolae modulate GBM cell invasion in part via matrix protease expression.
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a variable undecad repeat domain in cavin1 regulates caveola formation and stability
EMBO Reports, 2018Co-Authors: Vikas A Tillu, Charles Ferguson, Thomas E. Hall, Kerrie-ann Mcmahon, Michele Bastiani, Yewheen Lim, Oleksiy Kovtun, Sergey Mureev, Kirill Alexandrov, Brett M CollinsAbstract:Caveolae are plasma membrane invaginations involved in transport, signalling and mechanical membrane sensing in metazoans. Their formation depends upon multiple interactions between membrane-embedded caveolins, lipids and cytosolic cavin proteins. Of the four cavin family members, only cavin1 is strictly required for caveola formation. Here, we demonstrate that an eleven residue (undecad) repeat sequence (UC1) exclusive to cavin1 is essential for caveolar localization and promotes membrane remodelling through binding to phosphatidylserine. In the notochord of mechanically stimulated zebrafish embryos, the UC1 domain is required for caveolar stability and resistance to membrane stress. The number of undecad repeats in the cavin1 UC1 domain varies throughout evolution, and we find that an increased number also correlates with increased caveolar stability. Lastly, we show that the cavin1 UC1 domain induces dramatic remodelling of the plasma membrane when grafted into cavin2 suggesting an important role in membrane sculpting. Overall, our work defines a novel conserved cavin1 modular domain that controls caveolar assembly and stability.
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Endocytic Crosstalk: Cavins, Caveolins, and Caveolae Regulate Clathrin-Independent Endocytosis
2016Co-Authors: Natasha Chaudhary, Guillermo A. Gomez, Mark T. Howes, Kerrie-ann Mcmahon, James A. Rae, Nicole L. Schieber, Michelle M. Hill, Katharina Gaus, Alpha S. YapAbstract:Several studies have suggested crosstalk between different clathrin-independent endocytic pathways. However, the molecular mechanisms and functional relevance of these interactions are unclear. Caveolins and cavins are crucial components of Caveolae, specialized microdomains that also constitute an endocytic route. Here we show that specific caveolar proteins are independently acting negative regulators of clathrin-independent endocytosis. Cavin-1 and Cavin-3, but not Cavin-2 or Cavin-4, are potent inhibitors of the clathrin-independent carriers/GPI-AP enriched early endosomal compartment (CLIC/GEEC) endocytic pathway, in a process independent of caveola formation. Caveolin-1 (CAV1) and CAV3 also inhibit the CLIC/GEEC pathway upon over-expression. Expression of caveolar protein leads to reduction in formation of early CLIC/GEEC carriers, as detected by quantitative electron microscopy analysis. Furthermore, the CLIC/GEEC pathway is upregulated in cells lacking CAV1/Cavin-1 or with reduced expression of Cavin-1 and Cavin-3. Inhibition by caveolins can be mimicked by the isolated caveolin scaffolding domain and is associated with perturbed diffusion of lipid microdomain components, as revealed by fluorescence recovery after photobleaching (FRAP) studies. In the absence of cavins (and Caveolae) CAV1 is itself endocytosed preferentially through the CLIC/GEEC pathway, but the pathway loses polarization and sorting attributes with consequences for membrane dynamics and endocytic polarization in migrating cells and adult muscle tissue. We also found that noncaveolar Cavin-1 can act as a modulator for the activity of the key regulator of th