1
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Lim JE, Bernatchez P, Nabi IR. Scaffolds and the scaffolding domain: an alternative paradigm for caveolin-1 signaling. Biochem Soc Trans 2024; 52:947-959. [PMID: 38526159 PMCID: PMC11088920 DOI: 10.1042/bst20231570] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Revised: 03/10/2024] [Accepted: 03/11/2024] [Indexed: 03/26/2024]
Abstract
Caveolin-1 (Cav1) is a 22 kDa intracellular protein that is the main protein constituent of bulb-shaped membrane invaginations known as caveolae. Cav1 can be also found in functional non-caveolar structures at the plasma membrane called scaffolds. Scaffolds were originally described as SDS-resistant oligomers composed of 10-15 Cav1 monomers observable as 8S complexes by sucrose velocity gradient centrifugation. Recently, cryoelectron microscopy (cryoEM) and super-resolution microscopy have shown that 8S complexes are interlocking structures composed of 11 Cav1 monomers each, which further assemble modularly to form higher-order scaffolds and caveolae. In addition, Cav1 can act as a critical signaling regulator capable of direct interactions with multiple client proteins, in particular, the endothelial nitric oxide (NO) synthase (eNOS), a role believed by many to be attributable to the highly conserved and versatile scaffolding domain (CSD). However, as the CSD is a hydrophobic domain located by cryoEM to the periphery of the 8S complex, it is predicted to be enmeshed in membrane lipids. This has led some to challenge its ability to interact directly with client proteins and argue that it impacts signaling only indirectly via local alteration of membrane lipids. Here, based on recent advances in our understanding of higher-order Cav1 structure formation, we discuss how the Cav1 CSD may function through both lipid and protein interaction and propose an alternate view in which structural modifications to Cav1 oligomers may impact exposure of the CSD to cytoplasmic client proteins, such as eNOS.
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Affiliation(s)
- John E. Lim
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
- Department of Anesthesiology, Pharmacology and Therapeutics, Faculty of Medicine, University of British Columbia (UBC), 2176 Health Sciences Mall, Room 217, Vancouver, BC V6T 1Z3, Canada
| | - Pascal Bernatchez
- Department of Anesthesiology, Pharmacology and Therapeutics, Faculty of Medicine, University of British Columbia (UBC), 2176 Health Sciences Mall, Room 217, Vancouver, BC V6T 1Z3, Canada
- Centre for Heart and Lung Innovation, St. Paul's Hospital, Vancouver, Canada
| | - Ivan R. Nabi
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
- School of Biomedical Engineering, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
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2
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Monteiro P, Remy D, Lemerle E, Routet F, Macé AS, Guedj C, Ladoux B, Vassilopoulos S, Lamaze C, Chavrier P. A mechanosensitive caveolae-invadosome interplay drives matrix remodelling for cancer cell invasion. Nat Cell Biol 2023; 25:1787-1803. [PMID: 37903910 PMCID: PMC10709148 DOI: 10.1038/s41556-023-01272-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Accepted: 09/22/2023] [Indexed: 11/01/2023]
Abstract
Invadosomes and caveolae are mechanosensitive structures that are implicated in metastasis. Here, we describe a unique juxtaposition of caveola clusters and matrix degradative invadosomes at contact sites between the plasma membrane of cancer cells and constricting fibrils both in 2D and 3D type I collagen matrix environments. Preferential association between caveolae and straight segments of the fibrils, and between invadosomes and bent segments of the fibrils, was observed along with matrix remodelling. Caveola recruitment precedes and is required for invadosome formation and activity. Reciprocally, invadosome disruption results in the accumulation of fibril-associated caveolae. Moreover, caveolae and the collagen receptor β1 integrin co-localize at contact sites with the fibrils, and integrins control caveola recruitment to fibrils. In turn, caveolae mediate the clearance of β1 integrin and collagen uptake in an invadosome-dependent and collagen-cleavage-dependent mechanism. Our data reveal a reciprocal interplay between caveolae and invadosomes that coordinates adhesion to and proteolytic remodelling of confining fibrils to support tumour cell dissemination.
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Affiliation(s)
- Pedro Monteiro
- Actin and Membrane Dynamics Laboratory, Institut Curie-Research Center, CNRS UMR144, PSL Research University, Paris, France.
- Membrane Mechanics and Dynamics of Intracellular Signalling Laboratory, Institut Curie-Research Center, CNRS UMR3666, INSERM U1143, PSL Research University, Paris, France.
| | - David Remy
- Actin and Membrane Dynamics Laboratory, Institut Curie-Research Center, CNRS UMR144, PSL Research University, Paris, France
| | - Eline Lemerle
- Institute of Myology, Sorbonne Université, INSERM UMRS 974, Paris, France
| | - Fiona Routet
- Actin and Membrane Dynamics Laboratory, Institut Curie-Research Center, CNRS UMR144, PSL Research University, Paris, France
| | - Anne-Sophie Macé
- Cell and Tissue Imaging Facility (PICT-IBiSA), Institut Curie, PSL Research University, Paris, France
| | - Chloé Guedj
- Cell and Tissue Imaging Facility (PICT-IBiSA), Institut Curie, PSL Research University, Paris, France
| | - Benoit Ladoux
- Institut Jacques Monod, Université de Paris, CNRS UMR 7592, Paris, France
| | | | - Christophe Lamaze
- Membrane Mechanics and Dynamics of Intracellular Signalling Laboratory, Institut Curie-Research Center, CNRS UMR3666, INSERM U1143, PSL Research University, Paris, France.
| | - Philippe Chavrier
- Actin and Membrane Dynamics Laboratory, Institut Curie-Research Center, CNRS UMR144, PSL Research University, Paris, France.
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3
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Caveolin-1 dolines form a distinct and rapid caveolae-independent mechanoadaptation system. Nat Cell Biol 2023; 25:120-133. [PMID: 36543981 PMCID: PMC9859760 DOI: 10.1038/s41556-022-01034-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Accepted: 10/21/2022] [Indexed: 12/24/2022]
Abstract
In response to different types and intensities of mechanical force, cells modulate their physical properties and adapt their plasma membrane (PM). Caveolae are PM nano-invaginations that contribute to mechanoadaptation, buffering tension changes. However, whether core caveolar proteins contribute to PM tension accommodation independently from the caveolar assembly is unknown. Here we provide experimental and computational evidence supporting that caveolin-1 confers deformability and mechanoprotection independently from caveolae, through modulation of PM curvature. Freeze-fracture electron microscopy reveals that caveolin-1 stabilizes non-caveolar invaginations-dolines-capable of responding to low-medium mechanical forces, impacting downstream mechanotransduction and conferring mechanoprotection to cells devoid of caveolae. Upon cavin-1/PTRF binding, doline size is restricted and membrane buffering is limited to relatively high forces, capable of flattening caveolae. Thus, caveolae and dolines constitute two distinct albeit complementary components of a buffering system that allows cells to adapt efficiently to a broad range of mechanical stimuli.
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4
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Matthaeus C, Sochacki KA, Dickey AM, Puchkov D, Haucke V, Lehmann M, Taraska JW. The molecular organization of differentially curved caveolae indicates bendable structural units at the plasma membrane. Nat Commun 2022; 13:7234. [PMID: 36433988 PMCID: PMC9700719 DOI: 10.1038/s41467-022-34958-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Accepted: 11/11/2022] [Indexed: 11/27/2022] Open
Abstract
Caveolae are small coated plasma membrane invaginations with diverse functions. Caveolae undergo curvature changes. Yet, it is unclear which proteins regulate this process. To address this gap, we develop a correlative stimulated emission depletion (STED) fluorescence and platinum replica electron microscopy imaging (CLEM) method to image proteins at single caveolae. Caveolins and cavins are found at all caveolae, independent of curvature. EHD2 is detected at both low and highly curved caveolae. Pacsin2 associates with low curved caveolae and EHBP1 with mostly highly curved caveolae. Dynamin is absent from caveolae. Cells lacking dynamin show no substantial changes to caveolae, suggesting that dynamin is not directly involved in caveolae curvature. We propose a model where caveolins, cavins, and EHD2 assemble as a cohesive structural unit regulated by intermittent associations with pacsin2 and EHBP1. These coats can flatten and curve to enable lipid traffic, signaling, and changes to the surface area of the cell.
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Affiliation(s)
- Claudia Matthaeus
- Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Kem A Sochacki
- Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Andrea M Dickey
- Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Dmytro Puchkov
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany
| | - Volker Haucke
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany
- Faculty of Biology, Chemistry and Pharmacy, Freie Universität Berlin, Berlin, Germany
| | - Martin Lehmann
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany
| | - Justin W Taraska
- Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA.
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5
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Nishimura T, Suetsugu S. Super-resolution analysis of PACSIN2 and EHD2 at caveolae. PLoS One 2022; 17:e0271003. [PMID: 35834519 PMCID: PMC9282494 DOI: 10.1371/journal.pone.0271003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Accepted: 06/21/2022] [Indexed: 11/21/2022] Open
Abstract
Caveolae are plasma membrane invaginations that play important roles in both endocytosis and membrane tension buffering. Typical caveolae have invaginated structures with a high-density caveolin assembly. Membrane sculpting proteins, including PACSIN2 and EHD2, are involved in caveolar biogenesis. PACSIN2 is an F-BAR domain-containing protein with a membrane sculpting ability that is essential for caveolar shaping. EHD2 is also localized at caveolae and involved in their stability. However, the spatial relationship between PACSIN2, EHD2, and caveolin has not yet been investigated. We observed the single-molecule localizations of PACSIN2 and EHD2 relative to caveolin-1 in three-dimensional space. The single-molecule localizations were grouped by their proximity localizations into the geometric structures of blobs. In caveolin-1 blobs, PACSIN2, EHD2, and caveolin-1 had overlapped spatial localizations. Interestingly, the mean centroid of the PACSIN2 F-BAR domain at the caveolin-1 blobs was closer to the plasma membrane than those of EHD2 and caveolin-1, suggesting that PACSIN2 is involved in connecting caveolae to the plasma membrane. Most of the blobs with volumes typical of caveolae had PACSIN2 and EHD2, in contrast to those with smaller volumes. Therefore, PACSIN2 and EHD2 are apparently localized at typically sized caveolae.
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Affiliation(s)
- Tamako Nishimura
- Division of Biological Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, Ikoma, Japan
| | - Shiro Suetsugu
- Division of Biological Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, Ikoma, Japan
- Data Science Center, Nara Institute of Science and Technology, Ikoma, Japan
- Center for Digital Green-innovation, Nara Institute of Science and Technology, Ikoma, Japan
- * E-mail:
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6
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Osuga M, Nishimura T, Suetsugu S. Development of a green reversibly photoswitchable variant of Eos fluorescent protein with fixation resistance. Mol Biol Cell 2021; 32:br7. [PMID: 34495704 PMCID: PMC8693962 DOI: 10.1091/mbc.e21-01-0044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 08/23/2021] [Accepted: 09/01/2021] [Indexed: 11/11/2022] Open
Abstract
Superresolution microscopy determines the localization of fluorescent proteins with high precision, beyond the diffraction limit of light. Superresolution microscopic techniques include photoactivated localization microscopy (PALM), which can localize a single protein by the stochastic activation of its fluorescence. In the determination of single-molecule localization by PALM, the number of molecules that can be analyzed per image is limited. Thus, many images are required to reconstruct the localization of numerous molecules in the cell. However, most fluorescent proteins lose their fluorescence upon fixation. Here, we combined the amino acid substitutions of two Eos protein derivatives, Skylan-S and mEos4b, which are a green reversibly photoswitchable fluorescent protein (RSFP) and a fixation-resistant green-to-red photoconvertible fluorescent protein, respectively, resulting in the fixation-resistant Skylan-S (frSkylan-S), a green RSFP. The frSkylan-S protein is inactivated by excitation light and reactivated by irradiation with violet light, and retained more fluorescence after aldehyde fixation than Skylan-S. The qualities of the frSkylan-S fusion proteins were sufficiently high in PALM observations, as examined using α-tubulin and clathrin light chain. Furthermore, frSkylan-S can be combined with antibody staining for multicolor imaging. Therefore, frSkylan-S is a green fluorescent protein suitable for PALM imaging under aldehyde-fixation conditions.
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Affiliation(s)
- Mitsuo Osuga
- Nara Institute of Science and Technology, Ikoma 630-0192, Japan
| | | | - Shiro Suetsugu
- Nara Institute of Science and Technology, Ikoma 630-0192, Japan
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7
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Rezola M, Castellanos A, Gasull X, Comes N. Functional Interaction Between Caveolin 1 and LRRC8-Mediated Volume-Regulated Anion Channel. Front Physiol 2021; 12:691045. [PMID: 34658903 PMCID: PMC8517123 DOI: 10.3389/fphys.2021.691045] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Accepted: 09/06/2021] [Indexed: 11/13/2022] Open
Abstract
Volume-regulated anion channel (VRAC), constituted by leucine-rich repeat-containing 8 (LRRC8) heteromers, is crucial for volume homeostasis in vertebrate cells. This widely expressed channel has been associated with membrane potential modulation, proliferation, migration, apoptosis, and glutamate release. VRAC is activated by cell swelling and by low cytoplasmic ionic strength or intracellular guanosine 5′-O-(3-thiotriphosphate) (GTP-γS) in isotonic conditions. Despite the substantial number of studies that characterized the biophysical properties of VRAC, its mechanism of activation remains a mystery. Different evidence suggests a possible effect of caveolins in modulating VRAC activity: (1) Caveolin 1 (Cav1)-deficient cells display insignificant swelling-induced Cl– currents mediated by VRAC, which can be restored by Cav1 expression; (2) Caveolin 3 (Cav3) knockout mice display reduced VRAC currents; and (3) Interaction between LRRC8A, the essential subunit for VRAC, and Cav3 has been found in transfected human embryonic kidney 293 (HEK 293) cells. In this study, we demonstrate a physical interaction between endogenous LRRC8A and Cav1 proteins, that is enhanced by hypotonic stimulation, suggesting that this will increase the availability of the channel to Cav1. In addition, LRRC8A targets plasma membrane regions outside caveolae of HEK 293 cells where it associates with non-caveolar Cav1. We propose that a rise in cell membrane tension by hypotonicity would flatten caveolae, as described previously, increasing the amount of Cav1 outside of caveolar structures interacting with VRAC. Besides, the expression of Cav1 in HEK Cav1- cells increases VRAC current density without changing the main biophysical properties of the channel. The present study provides further evidence on the relevance of Cav1 on the activation of endothelial VRAC through a functional molecular interaction.
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Affiliation(s)
- Mikel Rezola
- Neurophysiology Laboratory, Physiology Unit, Department of Biomedicine, Medical School, Institute of Neurosciences, University of Barcelona, Barcelona, Spain
| | - Aida Castellanos
- Neurophysiology Laboratory, Physiology Unit, Department of Biomedicine, Medical School, Institute of Neurosciences, University of Barcelona, Barcelona, Spain
| | - Xavier Gasull
- Neurophysiology Laboratory, Physiology Unit, Department of Biomedicine, Medical School, Institute of Neurosciences, University of Barcelona, Barcelona, Spain.,Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
| | - Núria Comes
- Neurophysiology Laboratory, Physiology Unit, Department of Biomedicine, Medical School, Institute of Neurosciences, University of Barcelona, Barcelona, Spain.,Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
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8
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Shrestha A, Pinaud F, Haselwandter CA. Mechanics of cup-shaped caveolae. Phys Rev E 2021; 104:L022401. [PMID: 34525615 DOI: 10.1103/physreve.104.l022401] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Accepted: 07/16/2021] [Indexed: 11/07/2022]
Abstract
Caveolae are cell membrane invaginations of defined lipid and protein composition that flatten with increasing membrane tension. Super-resolution light microscopy and electron microscopy have revealed that caveolae can take a variety of cuplike shapes. We show here that, for the range in membrane tension relevant for cell membranes, the competition between membrane tension and membrane bending yields caveolae with cuplike shapes similar to those observed experimentally. We find that the caveola shape and its sensitivity to changes in membrane tension can depend strongly on the caveola spontaneous curvature and on the size of caveola domains. Our results suggest that heterogeneity in caveola shape produces a staggered response of caveolae to mechanical perturbations of the cell membrane, which may facilitate regulation of membrane tension over the wide range of scales thought to be relevant for cell membranes.
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Affiliation(s)
- Ahis Shrestha
- Department of Physics and Astronomy and Department of Quantitative and Computational Biology, University of Southern California, Los Angeles, California 90089, USA
| | - Fabien Pinaud
- Department of Biological Sciences, Department of Physics and Astronomy, and Department of Chemistry, University of Southern California, Los Angeles, California 90089, USA
| | - Christoph A Haselwandter
- Department of Physics and Astronomy and Department of Quantitative and Computational Biology, University of Southern California, Los Angeles, California 90089, USA
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9
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Wong TH, Khater IM, Joshi B, Shahsavari M, Hamarneh G, Nabi IR. Single molecule network analysis identifies structural changes to caveolae and scaffolds due to mutation of the caveolin-1 scaffolding domain. Sci Rep 2021; 11:7810. [PMID: 33833286 PMCID: PMC8032680 DOI: 10.1038/s41598-021-86770-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Accepted: 03/15/2021] [Indexed: 11/22/2022] Open
Abstract
Caveolin-1 (CAV1), the caveolae coat protein, also associates with non-caveolar scaffold domains. Single molecule localization microscopy (SMLM) network analysis distinguishes caveolae and three scaffold domains, hemispherical S2 scaffolds and smaller S1B and S1A scaffolds. The caveolin scaffolding domain (CSD) is a highly conserved hydrophobic region that mediates interaction of CAV1 with multiple effector molecules. F92A/V94A mutation disrupts CSD function, however the structural impact of CSD mutation on caveolae or scaffolds remains unknown. Here, SMLM network analysis quantitatively shows that expression of the CAV1 CSD F92A/V94A mutant in CRISPR/Cas CAV1 knockout MDA-MB-231 breast cancer cells reduces the size and volume and enhances the elongation of caveolae and scaffold domains, with more pronounced effects on S2 and S1B scaffolds. Convex hull analysis of the outer surface of the CAV1 point clouds confirms the size reduction of CSD mutant CAV1 blobs and shows that CSD mutation reduces volume variation amongst S2 and S1B CAV1 blobs at increasing shrink values, that may reflect retraction of the CAV1 N-terminus towards the membrane, potentially preventing accessibility of the CSD. Detection of point mutation-induced changes to CAV1 domains highlights the utility of SMLM network analysis for mesoscale structural analysis of oligomers in their native environment.
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Affiliation(s)
- Timothy H Wong
- Life Sciences Institute, Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, BC, V6T 1Z3, Canada
| | - Ismail M Khater
- School of Computing Science, Simon Fraser University, Burnaby, BC, V5A 1S6, Canada
| | - Bharat Joshi
- Life Sciences Institute, Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, BC, V6T 1Z3, Canada
| | - Mona Shahsavari
- School of Computing Science, Simon Fraser University, Burnaby, BC, V5A 1S6, Canada
| | - Ghassan Hamarneh
- School of Computing Science, Simon Fraser University, Burnaby, BC, V5A 1S6, Canada.
| | - Ivan R Nabi
- Life Sciences Institute, Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, BC, V6T 1Z3, Canada. .,School of Biomedical Engineering, University of British Columbia, Vancouver, BC, V6T 1Z3, Canada.
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10
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Abstract
Caveolae are bulb-like invaginations made up of two essential structural proteins, caveolin-1 and cavins, which are abundantly present at the plasma membrane of vertebrate cells. Since their discovery more than 60 years ago, the function of caveolae has been mired in controversy. The last decade has seen the characterization of new caveolae components and regulators together with the discovery of additional cellular functions that have shed new light on these enigmatic structures. Early on, caveolae and/or caveolin-1 have been involved in the regulation of several parameters associated with cancer progression such as cell migration, metastasis, angiogenesis, or cell growth. These studies have revealed that caveolin-1 and more recently cavin-1 have a dual role with either a negative or a positive effect on most of these parameters. The recent discovery that caveolae can act as mechanosensors has sparked an array of new studies that have addressed the mechanobiology of caveolae in various cellular functions. This review summarizes the current knowledge on caveolae and their role in cancer development through their activity in membrane tension buffering. We propose that the role of caveolae in cancer has to be revisited through their response to the mechanical forces encountered by cancer cells during tumor mass development.
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Affiliation(s)
- Vibha Singh
- UMR3666, INSERM U1143, Membrane Mechanics and Dynamics of Intracellular Signaling Laboratory, Institut Curie - Centre de Recherche, PSL Research University, CNRS, 75005, Paris, France
| | - Christophe Lamaze
- UMR3666, INSERM U1143, Membrane Mechanics and Dynamics of Intracellular Signaling Laboratory, Institut Curie - Centre de Recherche, PSL Research University, CNRS, 75005, Paris, France.
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11
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Lolo FN, Jiménez-Jiménez V, Sánchez-Álvarez M, Del Pozo MÁ. Tumor-stroma biomechanical crosstalk: a perspective on the role of caveolin-1 in tumor progression. Cancer Metastasis Rev 2021; 39:485-503. [PMID: 32514892 DOI: 10.1007/s10555-020-09900-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Tumor stiffening is a hallmark of malignancy that actively drives tumor progression and aggressiveness. Recent research has shed light onto several molecular underpinnings of this biomechanical process, which has a reciprocal crosstalk between tumor cells, stromal fibroblasts, and extracellular matrix remodeling at its core. This dynamic communication shapes the tumor microenvironment; significantly determines disease features including therapeutic resistance, relapse, or metastasis; and potentially holds the key for novel antitumor strategies. Caveolae and their components emerge as integrators of different aspects of cell function, mechanotransduction, and ECM-cell interaction. Here, we review our current knowledge on the several pivotal roles of the essential caveolar component caveolin-1 in this multidirectional biomechanical crosstalk and highlight standing questions in the field.
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Affiliation(s)
- Fidel Nicolás Lolo
- Mechanoadaptation and Caveolae Biology Lab, Cell and Developmental Biology Area, Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain
| | - Víctor Jiménez-Jiménez
- Mechanoadaptation and Caveolae Biology Lab, Cell and Developmental Biology Area, Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain
| | - Miguel Sánchez-Álvarez
- Mechanoadaptation and Caveolae Biology Lab, Cell and Developmental Biology Area, Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain
| | - Miguel Ángel Del Pozo
- Mechanoadaptation and Caveolae Biology Lab, Cell and Developmental Biology Area, Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain.
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12
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Abstract
Caveolin-1 (CAV1) has long been implicated in cancer progression, and while widely accepted as an oncogenic protein, CAV1 also has tumor suppressor activity. CAV1 was first identified in an early study as the primary substrate of Src kinase, a potent oncoprotein, where its phosphorylation correlated with cellular transformation. Indeed, CAV1 phosphorylation on tyrosine-14 (Y14; pCAV1) has been associated with several cancer-associated processes such as focal adhesion dynamics, tumor cell migration and invasion, growth suppression, cancer cell metabolism, and mechanical and oxidative stress. Despite this, a clear understanding of the role of Y14-phosphorylated pCAV1 in cancer progression has not been thoroughly established. Here, we provide an overview of the role of Src-dependent phosphorylation of tumor cell CAV1 in cancer progression, focusing on pCAV1 in tumor cell migration, focal adhesion signaling and metabolism, and in the cancer cell response to stress pathways characteristic of the tumor microenvironment. We also discuss a model for Y14 phosphorylation regulation of CAV1 effector protein interactions via the caveolin scaffolding domain.
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13
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Matthaeus C, Taraska JW. Energy and Dynamics of Caveolae Trafficking. Front Cell Dev Biol 2021; 8:614472. [PMID: 33692993 PMCID: PMC7939723 DOI: 10.3389/fcell.2020.614472] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Accepted: 12/21/2020] [Indexed: 12/19/2022] Open
Abstract
Caveolae are 70–100 nm diameter plasma membrane invaginations found in abundance in adipocytes, endothelial cells, myocytes, and fibroblasts. Their bulb-shaped membrane domain is characterized and formed by specific lipid binding proteins including Caveolins, Cavins, Pacsin2, and EHD2. Likewise, an enrichment of cholesterol and other lipids makes caveolae a distinct membrane environment that supports proteins involved in cell-type specific signaling pathways. Their ability to detach from the plasma membrane and move through the cytosol has been shown to be important for lipid trafficking and metabolism. Here, we review recent concepts in caveolae trafficking and dynamics. Second, we discuss how ATP and GTP-regulated proteins including dynamin and EHD2 control caveolae behavior. Throughout, we summarize the potential physiological and cell biological roles of caveolae internalization and trafficking and highlight open questions in the field and future directions for study.
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Affiliation(s)
- Claudia Matthaeus
- Biochemistry and Biophysics Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, United States
| | - Justin W Taraska
- Biochemistry and Biophysics Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, United States
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14
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Dudãu M, Codrici E, Tanase C, Gherghiceanu M, Enciu AM, Hinescu ME. Caveolae as Potential Hijackable Gates in Cell Communication. Front Cell Dev Biol 2020; 8:581732. [PMID: 33195223 PMCID: PMC7652756 DOI: 10.3389/fcell.2020.581732] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Accepted: 10/08/2020] [Indexed: 12/16/2022] Open
Abstract
Caveolae are membrane microdomains described in many cell types involved in endocytocis, transcytosis, cell signaling, mechanotransduction, and aging. They are found at the interface with the extracellular environment and are structured by caveolin and cavin proteins. Caveolae and caveolins mediate transduction of chemical messages via signaling pathways, as well as non-chemical messages, such as stretching or shear stress. Various pathogens or signals can hijack these gates, leading to infectious, oncogenic and even caveolin-related diseases named caveolinopathies. By contrast, preclinical and clinical research have fallen behind in their attempts to hijack caveolae and caveolins for therapeutic purposes. Caveolae involvement in human disease is not yet fully explored or understood and, of all their scaffold proteins, only caveolin-1 is being considered in clinical trials as a possible biomarker of disease. This review briefly summarizes current knowledge about caveolae cell signaling and raises the hypothesis whether these microdomains could serve as hijackable “gatekeepers” or “gateways” in cell communication. Furthermore, because cell signaling is one of the most dynamic domains in translating data from basic to clinical research, we pay special attention to translation of caveolae, caveolin, and cavin research into clinical practice.
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Affiliation(s)
- Maria Dudãu
- Biochemistry-Proteomics Laboratory, Victor Babes National Institute of Pathology, Bucharest, Romania.,Cell Biology and Histology Department, Carol Davila University of Medicine and Pharmacy, Bucharest, Romania
| | - Elena Codrici
- Biochemistry-Proteomics Laboratory, Victor Babes National Institute of Pathology, Bucharest, Romania
| | - Cristiana Tanase
- Biochemistry-Proteomics Laboratory, Victor Babes National Institute of Pathology, Bucharest, Romania.,Clinical Biochemistry Department, Faculty of Medicine, Titu Maiorescu University, Bucharest, Romania
| | - Mihaela Gherghiceanu
- Biochemistry-Proteomics Laboratory, Victor Babes National Institute of Pathology, Bucharest, Romania.,Cell Biology and Histology Department, Carol Davila University of Medicine and Pharmacy, Bucharest, Romania
| | - Ana-Maria Enciu
- Biochemistry-Proteomics Laboratory, Victor Babes National Institute of Pathology, Bucharest, Romania.,Cell Biology and Histology Department, Carol Davila University of Medicine and Pharmacy, Bucharest, Romania
| | - Mihail E Hinescu
- Biochemistry-Proteomics Laboratory, Victor Babes National Institute of Pathology, Bucharest, Romania.,Cell Biology and Histology Department, Carol Davila University of Medicine and Pharmacy, Bucharest, Romania
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15
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Gusmira A, Takemura K, Lee SY, Inaba T, Hanawa-Suetsugu K, Oono-Yakura K, Yasuhara K, Kitao A, Suetsugu S. Regulation of caveolae through cholesterol-depletion-dependent tubulation mediated by PACSIN2. J Cell Sci 2020; 133:jcs246785. [PMID: 32878944 DOI: 10.1242/jcs.246785] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Accepted: 08/24/2020] [Indexed: 01/09/2023] Open
Abstract
The membrane-shaping ability of PACSIN2 (also known as syndapin II), which is mediated by its F-BAR domain, has been shown to be essential for caveolar morphogenesis, presumably through the shaping of the caveolar neck. Caveolar membranes contain abundant cholesterol. However, the role of cholesterol in PACSIN2-mediated membrane deformation remains unclear. Here, we show that the binding of PACSIN2 to the membrane can be negatively regulated by cholesterol. We prepared reconstituted membranes based on the lipid composition of caveolae. The reconstituted membrane with cholesterol had a weaker affinity for the F-BAR domain of PACSIN2 than a membrane without cholesterol. Consistent with this, upon depletion of cholesterol from the plasma membrane, PACSIN2 localized at tubules that had caveolin-1 at their tips, suggesting that cholesterol inhibits membrane tubulation mediated by PACSIN2. The tubules induced by PACSIN2 could be representative of an intermediate of caveolae endocytosis. Consistent with this, the removal of caveolae from the plasma membrane upon cholesterol depletion was diminished in the PACSIN2-deficient cells. These data suggest that PACSIN2-mediated caveolae internalization is dependent on the amount of cholesterol, providing a mechanism for cholesterol-dependent regulation of caveolae.This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Aini Gusmira
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan
| | - Kazuhiro Takemura
- School of Life Science and Technology, Tokyo Institute of Technology, Meguro, Tokyo 152-8550, Japan
| | - Shin Yong Lee
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan
| | - Takehiko Inaba
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan
| | - Kyoko Hanawa-Suetsugu
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan
| | - Kayoko Oono-Yakura
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan
| | - Kazuma Yasuhara
- Division of Material Science, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan
| | - Akio Kitao
- School of Life Science and Technology, Tokyo Institute of Technology, Meguro, Tokyo 152-8550, Japan
| | - Shiro Suetsugu
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan
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16
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Spatiotemporal Analysis of Caveolae Dynamics Using Total Internal Reflection Fluorescence Microscopy. Methods Mol Biol 2020. [PMID: 32548819 DOI: 10.1007/978-1-0716-0732-9_6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
Total internal reflection fluorescence microscopy enables to analyze the localizations and dynamics of cellular events that occur at or near the plasma membrane. Total internal reflection fluorescence microscopy exclusively illuminates molecules in the close vicinity of the glass surface, thereby reducing background fluorescence and enabling observation of the plasma membrane in the glass-attached cells with a high signal-to-noise ratio. Here, we describe the application of total internal reflection fluorescence microscopy to analyze the dynamics of caveolae, which play essential physiological functions, including membrane tension buffering, endocytosis, and signaling at the plasma membrane.
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17
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Hunt NJ, Lockwood GP, Le Couteur FH, McCourt PAG, Singla N, Kang SWS, Burgess A, Kuncic Z, Le Couteur DG, Cogger VC. Rapid Intestinal Uptake and Targeted Delivery to the Liver Endothelium Using Orally Administered Silver Sulfide Quantum Dots. ACS NANO 2020; 14:1492-1507. [PMID: 31976646 DOI: 10.1021/acsnano.9b06071] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Quantum dots (QDs) are used for imaging and transport of therapeutics. Here we demonstrate rapid absorption across the small intestine and targeted delivery of QDs with bound materials to the liver sinusoidal endothelial cells (LSECs) or hepatocytes in vitro and in vivo following oral administration. QDs were radiolabeled with 3H-oleic acid, with a fluorescent tag or 14C-metformin placed within a drug binding site. Three different biopolymer shell coatings were compared (formaldehyde-treated serum albumin (FSA), gelatin, heparin). Passage across the small intestine into mesenteric veins is mediated by clathrin endocytosis and micropinocytosis. 60% of an oral dose of QDs was rapidly distributed to the liver within 30 min, and this increased to 85% with FSA biopolymer coating. Uptake into LSECs also increased 3-fold with FSA coating, while uptake into hepatocytes was increased from 40% to 85% with gelatin biopolymer coating. Localization of QDs to LSECs was confirmed with immunofluorescence and transmission electron microscopy. 85% of QDs were cleared within 24 h of administration. The bioavailability of 14C-metformin 2 h post-ingestion was increased 5-fold by conjugation with QD-FSA, while uptake of metformin into LSECs was improved 50-fold by using these QDs. Endocytosis of QDs by SK-Hep1 cells (an LSEC immortal cell line) was via clathrin- and caveolae-mediated pathways with QDs taken up into lysosomes. In conclusion, we have shown high specificity targeting of the LSEC or hepatocytes after oral administration of QDs coated with a biopolymer layer of FSA or gelatin, which improved the bioavailability and delivery of metformin to LSECs.
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Affiliation(s)
- Nicholas J Hunt
- ANZAC Research Institute , Concord Repatriation General Hospital , Concord , New South Wales 2139 , Australia
- Aging and Alzheimer's Institute and Centre for Education and Research on Ageing , Concord Repatriation General Hospital , Concord , New South Wales 2139 , Australia
- Faculty of Medicine and Health , The University of Sydney , Sydney , New South Wales 2006 , Australia
- Charles Perkins Centre , The University of Sydney , Sydney , New South Wales 2006 , Australia
| | - Glen P Lockwood
- ANZAC Research Institute , Concord Repatriation General Hospital , Concord , New South Wales 2139 , Australia
- Aging and Alzheimer's Institute and Centre for Education and Research on Ageing , Concord Repatriation General Hospital , Concord , New South Wales 2139 , Australia
- Charles Perkins Centre , The University of Sydney , Sydney , New South Wales 2006 , Australia
| | - Frank H Le Couteur
- ANZAC Research Institute , Concord Repatriation General Hospital , Concord , New South Wales 2139 , Australia
| | - Peter A G McCourt
- Charles Perkins Centre , The University of Sydney , Sydney , New South Wales 2006 , Australia
- Department of Medical Biology , University of Tromsø - The Arctic University of Norway , Tromsø 9037 , Norway
| | - Nidhi Singla
- Nano Institute , The University of Sydney , Sydney , New South Wales 2006 , Australia
| | - Sun Woo Sophie Kang
- ANZAC Research Institute , Concord Repatriation General Hospital , Concord , New South Wales 2139 , Australia
- Aging and Alzheimer's Institute and Centre for Education and Research on Ageing , Concord Repatriation General Hospital , Concord , New South Wales 2139 , Australia
- Faculty of Medicine and Health , The University of Sydney , Sydney , New South Wales 2006 , Australia
| | - Andrew Burgess
- ANZAC Research Institute , Concord Repatriation General Hospital , Concord , New South Wales 2139 , Australia
- Faculty of Medicine and Health , The University of Sydney , Sydney , New South Wales 2006 , Australia
| | - Zdenka Kuncic
- Charles Perkins Centre , The University of Sydney , Sydney , New South Wales 2006 , Australia
- School of Physics , The University of Sydney , Sydney , New South Wales 2006 , Australia
- Nano Institute , The University of Sydney , Sydney , New South Wales 2006 , Australia
| | - David G Le Couteur
- ANZAC Research Institute , Concord Repatriation General Hospital , Concord , New South Wales 2139 , Australia
- Aging and Alzheimer's Institute and Centre for Education and Research on Ageing , Concord Repatriation General Hospital , Concord , New South Wales 2139 , Australia
- Faculty of Medicine and Health , The University of Sydney , Sydney , New South Wales 2006 , Australia
- Charles Perkins Centre , The University of Sydney , Sydney , New South Wales 2006 , Australia
| | - Victoria C Cogger
- ANZAC Research Institute , Concord Repatriation General Hospital , Concord , New South Wales 2139 , Australia
- Aging and Alzheimer's Institute and Centre for Education and Research on Ageing , Concord Repatriation General Hospital , Concord , New South Wales 2139 , Australia
- Faculty of Medicine and Health , The University of Sydney , Sydney , New South Wales 2006 , Australia
- Charles Perkins Centre , The University of Sydney , Sydney , New South Wales 2006 , Australia
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18
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Wei X, She G, Wu T, Xue C, Cao Y. PEDV enters cells through clathrin-, caveolae-, and lipid raft-mediated endocytosis and traffics via the endo-/lysosome pathway. Vet Res 2020; 51:10. [PMID: 32041637 PMCID: PMC7011528 DOI: 10.1186/s13567-020-0739-7] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2019] [Accepted: 01/07/2020] [Indexed: 12/21/2022] Open
Abstract
With the emergence of highly pathogenic variant strains, porcine epidemic diarrhea virus (PEDV) has led to significant economic loss in the global swine industry. Many studies have described how coronaviruses enter cells, but information on PEDV invasion strategies remains insufficient. Given that the differences in gene sequences and pathogenicity between classical and mutant strains of PEDV may lead to diverse invasion mechanisms, this study focused on the cellular entry pathways and cellular transport of the PEDV GI and GII subtype strains in Vero cells and IPEC-J2 cells. We first characterized the kinetics of PEDV entry into cells and found that the highest invasion rate of PEDV was approximately 33% in the IPEC-J2 cells and approximately 100% in the Vero cells. To clarify the specific endocytic pathways, systematic research methods were used and showed that PEDV enters cells via the clathrin- and caveolae-mediated endocytosis pathways, in which dynamin II, clathrin heavy chain, Eps15, cholesterol, and caveolin-1 were indispensably involved. In addition, lipid raft extraction assay showed that PEDV can also enter cells through lipid raft-mediated endocytosis. To investigate the trafficking of internalized PEDV, we found that PEDV entry into cells relied on low pH and internalized virions reached lysosomes through the early endosome-late endosome-lysosome pathway. The results concretely revealed the entry mechanisms of PEDV and provided an insightful theoretical basis for the further understanding of PEDV pathogenesis and guidance for new targets of antiviral drugs.
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Affiliation(s)
- Xiaona Wei
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, 510006, People's Republic of China
| | - Gaoli She
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, 510006, People's Republic of China
| | - Tingting Wu
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, 510006, People's Republic of China
| | - Chunyi Xue
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, 510006, People's Republic of China.
| | - Yongchang Cao
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, 510006, People's Republic of China.
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19
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Khater IM, Aroca-Ouellette ST, Meng F, Nabi IR, Hamarneh G. Caveolae and scaffold detection from single molecule localization microscopy data using deep learning. PLoS One 2019; 14:e0211659. [PMID: 31449531 PMCID: PMC6709882 DOI: 10.1371/journal.pone.0211659] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Accepted: 08/07/2019] [Indexed: 12/21/2022] Open
Abstract
Caveolae are plasma membrane invaginations whose formation requires caveolin-1 (Cav1), the adaptor protein polymerase I, and the transcript release factor (PTRF or CAVIN1). Caveolae have an important role in cell functioning, signaling, and disease. In the absence of CAVIN1/PTRF, Cav1 forms non-caveolar membrane domains called scaffolds. In this work, we train machine learning models to automatically distinguish between caveolae and scaffolds from single molecule localization microscopy (SMLM) data. We apply machine learning algorithms to discriminate biological structures from SMLM data. Our work is the first that is leveraging machine learning approaches (including deep learning models) to automatically identifying biological structures from SMLM data. In particular, we develop and compare three binary classification methods to identify whether or not a given 3D cluster of Cav1 proteins is a caveolae. The first uses a random forest classifier applied to 28 hand-crafted/designed features, the second uses a convolutional neural net (CNN) applied to a projection of the point clouds onto three planes, and the third uses a PointNet model, a recent development that can directly take point clouds as its input. We validate our methods on a dataset of super-resolution microscopy images of PC3 prostate cancer cells labeled for Cav1. Specifically, we have images from two cell populations: 10 PC3 and 10 CAVIN1/PTRF-transfected PC3 cells (PC3-PTRF cells) that form caveolae. We obtained a balanced set of 1714 different cellular structures. Our results show that both the random forest on hand-designed features and the deep learning approach achieve high accuracy in distinguishing the intrinsic features of the caveolae and non-caveolae biological structures. More specifically, both random forest and deep CNN classifiers achieve classification accuracy reaching 94% on our test set, while the PointNet model only reached 83% accuracy. We also discuss the pros and cons of the different approaches.
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Affiliation(s)
- Ismail M. Khater
- Medical Image Analysis Lab, School of Computing Science, Simon Fraser University, Burnaby, BC V5A 1S6, Canada
- * E-mail:
| | - Stephane T. Aroca-Ouellette
- Medical Image Analysis Lab, School of Computing Science, Simon Fraser University, Burnaby, BC V5A 1S6, Canada
| | - Fanrui Meng
- Department of Cellular and Physiological Sciences, LSI Imaging, Life Sciences Institute, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Ivan Robert Nabi
- Department of Cellular and Physiological Sciences, LSI Imaging, Life Sciences Institute, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Ghassan Hamarneh
- Medical Image Analysis Lab, School of Computing Science, Simon Fraser University, Burnaby, BC V5A 1S6, Canada
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20
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Khater IM, Liu Q, Chou KC, Hamarneh G, Nabi IR. Super-resolution modularity analysis shows polyhedral caveolin-1 oligomers combine to form scaffolds and caveolae. Sci Rep 2019; 9:9888. [PMID: 31285524 PMCID: PMC6614455 DOI: 10.1038/s41598-019-46174-z] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Accepted: 06/20/2019] [Indexed: 01/22/2023] Open
Abstract
Caveolin-1 (Cav1), the coat protein for caveolae, also forms non-caveolar Cav1 scaffolds. Single molecule Cav1 super-resolution microscopy analysis previously identified caveolae and three distinct scaffold domains: smaller S1A and S2B scaffolds and larger hemispherical S2 scaffolds. Application here of network modularity analysis of SMLM data for endogenous Cav1 labeling in HeLa cells shows that small scaffolds combine to form larger scaffolds and caveolae. We find modules within Cav1 blobs by maximizing the intra-connectivity between Cav1 molecules within a module and minimizing the inter-connectivity between Cav1 molecules across modules, which is achieved via spectral decomposition of the localizations adjacency matrix. Features of modules are then matched with intact blobs to find the similarity between the module-blob pairs of group centers. Our results show that smaller S1A and S1B scaffolds are made up of small polygons, that S1B scaffolds correspond to S1A scaffold dimers and that caveolae and hemispherical S2 scaffolds are complex, modular structures formed from S1B and S1A scaffolds, respectively. Polyhedral interactions of Cav1 oligomers, therefore, leads progressively to the formation of larger and more complex scaffold domains and the biogenesis of caveolae.
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Affiliation(s)
- Ismail M Khater
- Medical Image Analysis Lab, School of Computing Science, Simon Fraser University, Burnaby, BC, V5A 1S6, Canada
| | - Qian Liu
- Department of Chemistry, University of British Columbia, Vancouver, BC, V6T 1Z1, Canada
| | - Keng C Chou
- Department of Chemistry, University of British Columbia, Vancouver, BC, V6T 1Z1, Canada
| | - Ghassan Hamarneh
- Medical Image Analysis Lab, School of Computing Science, Simon Fraser University, Burnaby, BC, V5A 1S6, Canada.
| | - Ivan Robert Nabi
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, BC, V6T 1Z3, Canada.
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21
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Chasing Uptake: Super-Resolution Microscopy in Endocytosis and Phagocytosis. Trends Cell Biol 2019; 29:727-739. [PMID: 31227311 DOI: 10.1016/j.tcb.2019.05.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Revised: 05/14/2019] [Accepted: 05/23/2019] [Indexed: 11/21/2022]
Abstract
Since their invention about two decades ago, super-resolution microscopes have become a method of choice in cell biology. Owing to a spatial resolution below 50 nm, smaller than the size of most organelles, and an order of magnitude better than the diffraction limit of conventional light microscopes, super-resolution microscopy is a powerful technique for resolving intracellular trafficking. In this review we discuss discoveries in endocytosis and phagocytosis that have been made possible by super-resolution microscopy - from uptake at the plasma membrane, endocytic coat formation, and cytoskeletal rearrangements to endosomal maturation. The detailed visualization of the diverse molecular assemblies that mediate endocytic uptake will provide a better understanding of how cells ingest extracellular material.
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22
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Phatvej W, Datta HK, Wilkinson SC, Mutch E, Daly AK, Horrocks BR. Endocytosis and Lack of Cytotoxicity of Alkyl-Capped Silicon Quantum Dots Prepared from Porous Silicon. MATERIALS 2019; 12:ma12101702. [PMID: 31130663 PMCID: PMC6566257 DOI: 10.3390/ma12101702] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Revised: 05/17/2019] [Accepted: 05/19/2019] [Indexed: 12/16/2022]
Abstract
Freely-dissolved silicon quantum dots were prepared by thermal hydrosilation of 1-undecene at high-porosity porous silicon under reflux in toluene. This reaction produces a suspension of alkyl-capped silicon quantum dots (alkyl SiQDs) with bright orange luminescence, a core Si nanocrystal diameter of about 2.5 nm and a total particle diameter of about 5 nm. Previous work has shown that these particles are rapidly endocytosed by malignant cell lines and have little or no acute toxicity as judged by the standard 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay for viability and the Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay for apoptosis. We have extended this work to the CACO-2 cell line, an established model for the human small intestinal mucosa, and demonstrate that neither acute nor chronic (14 days) toxicity is observed as judged by cell morphology, viability, ATP production, ROS production and DNA damage (single cell gel electrophoresis) at doses of 50–200 μg mL−1. Quantitative assessment of the extent of uptake of alkyl SiQDs by CACO-2, HeLa, HepG2, and Huh7 cell lines by flow cytometry showed a wide variation. The liver cell lines (HepG2 and Huh7) were the most active and HeLa and CACO-2 showed comparable activity. Previous work has reported a cholesterol-sensitivity of the endocytosis (HeLa), which suggests a caveolin-mediated pathway. However, gene expression analysis by quantitative real–time polymerase chain reaction (RT-PCR) indicates very low levels of caveolins 1 and 2 in HepG2 and much higher levels in HeLa. The data suggest that the mechanism of endocytosis of the alkyl SiQDs is cell-line dependent.
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Affiliation(s)
- Wipaporn Phatvej
- Thailand Institute of Scientific and Technological Research, Bangkok 10900, Thailand.
| | - Harish K Datta
- The James Cook University Hospital, Marton Road, Middlesbrough TS4 3BW, UK.
| | - Simon C Wilkinson
- Institute of Cellular Medicine, Medical School, Newcastle University, Newcastle NE1 7RU, UK.
| | - Elaine Mutch
- Toxicology Unit, Medical School, Newcastle University, Newcastle NE1 7RU, UK.
| | - Ann K Daly
- Institute of Cellular Medicine, Medical School, Newcastle University, Newcastle NE1 7RU, UK.
| | - Benjamin R Horrocks
- Chemical Nanoscience Laboratory, School of Natural and Environmental Sciences, Newcastle University, Newcastle NE1 7RU, UK.
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23
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Membrane re-modelling by BAR domain superfamily proteins via molecular and non-molecular factors. Biochem Soc Trans 2018. [PMID: 29540508 DOI: 10.1042/bst20170322] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Lipid membranes are structural components of cell surfaces and intracellular organelles. Alterations in lipid membrane shape are accompanied by numerous cellular functions, including endocytosis, intracellular transport, and cell migration. Proteins containing Bin-Amphiphysin-Rvs (BAR) domains (BAR proteins) are unique, because their structures correspond to the membrane curvature, that is, the shape of the lipid membrane. BAR proteins present at high concentration determine the shape of the membrane, because BAR domain oligomers function as scaffolds that mould the membrane. BAR proteins co-operate with various molecular and non-molecular factors. The molecular factors include cytoskeletal proteins such as the regulators of actin filaments and the membrane scission protein dynamin. Lipid composition, including saturated or unsaturated fatty acid tails of phospholipids, also affects the ability of BAR proteins to mould the membrane. Non-molecular factors include the external physical forces applied to the membrane, such as tension and friction. In this mini-review, we will discuss how the BAR proteins orchestrate membrane dynamics together with various molecular and non-molecular factors.
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