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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Julien JA, Rousseau A, Perone TV, LaGatta DM, Hong C, Root KT, Park S, Fuanta R, Im W, Glover KJ. One-step site-specific S-alkylation of full-length caveolin-1: Lipidation modulates the topology of its C-terminal domain. Protein Sci 2023; 32:e4791. [PMID: 37801623 PMCID: PMC10599104 DOI: 10.1002/pro.4791] [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: 04/25/2023] [Revised: 08/20/2023] [Accepted: 09/25/2023] [Indexed: 10/08/2023]
Abstract
Caveolin-1 is an integral membrane protein that is known to acquire a number of posttranslational modifications upon trafficking to the plasma membrane. In particular, caveolin-1 is palmitoylated at three cysteine residues (C133, C143, and C156) located within the C-terminal domain of the protein which could have structural and topological implications. Herein, a reliable preparation of full-length S-alkylated caveolin-1, which closely mimics the palmitoylation observed in vivo, is described. HPLC and ESI-LC-MS analyses verified the addition of the C16 alkyl groups to caveolin-1 constructs containing one (C133), two (C133 and C143), and three (C133, C143, and C156) cysteine residues. Circular dichroism spectroscopy analysis of the constructs revealed that S-alkylation does not significantly affect the global helicity of the protein; however, molecular dynamics simulations revealed that there were local regions where the helicity was altered positively or negatively by S-alkylation. In addition, the simulations showed that lipidation tames the topological promiscuity of the C-terminal domain, resulting in a disposition within the bilayer characterized by increased depth.
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Affiliation(s)
| | - Alain Rousseau
- Department of ChemistryLehigh UniversityBethlehemPennsylvaniaUSA
| | - Thomas V. Perone
- Department of ChemistryLehigh UniversityBethlehemPennsylvaniaUSA
| | - David M. LaGatta
- Department of ChemistryLehigh UniversityBethlehemPennsylvaniaUSA
| | - Chan Hong
- Department of ChemistryLehigh UniversityBethlehemPennsylvaniaUSA
| | - Kyle T. Root
- Department of Chemistry, Biochemistry, Engineering & PhysicsCommonwealth University of PennsylvaniaLock HavenPennsylvaniaUSA
| | - Soohyung Park
- Department of ChemistryLehigh UniversityBethlehemPennsylvaniaUSA
| | - René Fuanta
- Department of Chemistry & BiochemistryEast Stroudsburg UniversityEast StroudsburgPennsylvaniaUSA
| | - Wonpil Im
- Department of ChemistryLehigh UniversityBethlehemPennsylvaniaUSA
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3
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Gulsevin A, Han B, Porta JC, Mchaourab HS, Meiler J, Kenworthy AK. Template-free prediction of a new monotopic membrane protein fold and assembly by AlphaFold2. Biophys J 2023; 122:2041-2052. [PMID: 36352786 PMCID: PMC10257013 DOI: 10.1016/j.bpj.2022.11.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Revised: 10/20/2022] [Accepted: 11/04/2022] [Indexed: 11/11/2022] Open
Abstract
AlphaFold2 (AF2) has revolutionized the field of protein structural prediction. Here, we test its ability to predict the tertiary and quaternary structure of a previously undescribed scaffold with new folds and unusual architecture, the monotopic membrane protein caveolin-1 (CAV1). CAV1 assembles into a disc-shaped oligomer composed of 11 symmetrically arranged protomers, each assuming an identical new fold, and contains the largest parallel β-barrel known to exist in nature. Remarkably, AF2 predicts both the fold of the protomers and the interfaces between them. It also assembles between seven and 15 copies of CAV1 into disc-shaped complexes. However, the predicted multimers are energetically strained, especially the parallel β-barrel. These findings highlight the ability of AF2 to correctly predict new protein folds and oligomeric assemblies at a granular level while missing some elements of higher-order complexes, thus positing a new direction for the continued development of deep-learning protein structure prediction approaches.
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Affiliation(s)
- Alican Gulsevin
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee
| | - Bing Han
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, Virginia; Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, Virginia
| | - Jason C Porta
- Life Sciences Institute, University of Michigan, Ann Arbor, Michigan
| | - Hassane S Mchaourab
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee
| | - Jens Meiler
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee; Institute for Drug Discovery, Leipzig University, Leipzig, Germany.
| | - Anne K Kenworthy
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, Virginia; Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, Virginia.
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4
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Kenworthy AK. The building blocks of caveolae revealed: caveolins finally take center stage. Biochem Soc Trans 2023; 51:855-869. [PMID: 37082988 PMCID: PMC10212548 DOI: 10.1042/bst20221298] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Revised: 04/07/2023] [Accepted: 04/14/2023] [Indexed: 04/22/2023]
Abstract
The ability of cells to divide, migrate, relay signals, sense mechanical stimuli, and respond to stress all rely on nanoscale invaginations of the plasma membrane known as caveolae. The caveolins, a family of monotopic membrane proteins, form the inner layer of the caveolar coat. Caveolins have long been implicated in the generation of membrane curvature, in addition to serving as scaffolds for signaling proteins. Until recently, however, the molecular architecture of caveolins was unknown, making it impossible to understand how they operate at a mechanistic level. Over the past year, two independent lines of evidence - experimental and computational - have now converged to provide the first-ever glimpse into the structure of the oligomeric caveolin complexes that function as the building blocks of caveolae. Here, we summarize how these discoveries are transforming our understanding of this long-enigmatic protein family and their role in caveolae assembly and function. We present new models inspired by the structure for how caveolins oligomerize, remodel membranes, interact with their binding partners, and reorganize when mutated. Finally, we discuss emerging insights into structural differences among caveolin family members that enable them to support the proper functions of diverse tissues and organisms.
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Affiliation(s)
- Anne K. Kenworthy
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA, U.S.A
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA, U.S.A
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5
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Han B, Gulsevin A, Connolly S, Wang T, Meyer B, Porta J, Tiwari A, Deng A, Chang L, Peskova Y, Mchaourab HS, Karakas E, Ohi MD, Meiler J, Kenworthy AK. Structural analysis of the P132L disease mutation in caveolin-1 reveals its role in the assembly of oligomeric complexes. J Biol Chem 2023; 299:104574. [PMID: 36870682 PMCID: PMC10124911 DOI: 10.1016/j.jbc.2023.104574] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Revised: 01/09/2023] [Accepted: 02/03/2023] [Indexed: 03/06/2023] Open
Abstract
Caveolin-1 (CAV1) is a membrane-sculpting protein that oligomerizes to generate flask-shaped invaginations of the plasma membrane known as caveolae. Mutations in CAV1 have been linked to multiple diseases in humans. Such mutations often interfere with oligomerization and the intracellular trafficking processes required for successful caveolae assembly, but the molecular mechanisms underlying these defects have not been structurally explained. Here, we investigate how a disease-associated mutation in one of the most highly conserved residues in CAV1, P132L, affects CAV1 structure and oligomerization. We show that P132 is positioned at a major site of protomer-protomer interactions within the CAV1 complex, providing a structural explanation for why the mutant protein fails to homo-oligomerize correctly. Using a combination of computational, structural, biochemical, and cell biological approaches, we find that despite its homo-oligomerization defects P132L is capable of forming mixed hetero-oligomeric complexes with WT CAV1 and that these complexes can be incorporated into caveolae. These findings provide insights into the fundamental mechanisms that control the formation of homo- and hetero-oligomers of caveolins that are essential for caveolae biogenesis, as well as how these processes are disrupted in human disease.
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Affiliation(s)
- Bing Han
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA, USA; Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - Alican Gulsevin
- Department of Chemistry, Vanderbilt University, Nashville, TN, USA
| | - Sarah Connolly
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
| | - Ting Wang
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA, USA; Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - Brigitte Meyer
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - Jason Porta
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
| | - Ajit Tiwari
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA, USA; Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - Angie Deng
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, USA
| | - Louise Chang
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
| | - Yelena Peskova
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA, USA; Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - Hassane S Mchaourab
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, USA
| | - Erkan Karakas
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, USA
| | - Melanie D Ohi
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA; Department of Cell and Developmental Biology, University of Michigan School of Medicine, Ann Arbor, MI, USA
| | - Jens Meiler
- Department of Chemistry, Vanderbilt University, Nashville, TN, USA; Institute for Drug Discovery, Leipzig University, Leipzig, Germany
| | - Anne K Kenworthy
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA, USA; Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA, USA.
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6
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Wittka A, Ketteler J, Borgards L, Maier P, Herskind C, Jendrossek V, Klein D. Stromal Fibroblasts Counteract the Caveolin-1-Dependent Radiation Response of LNCaP Prostate Carcinoma Cells. Front Oncol 2022; 12:802482. [PMID: 35155239 PMCID: PMC8826751 DOI: 10.3389/fonc.2022.802482] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Accepted: 01/03/2022] [Indexed: 12/05/2022] Open
Abstract
In prostate cancer (PCa), a characteristic stromal–epithelial redistribution of the membrane protein caveolin 1 (CAV1) occurs upon tumor progression, where a gain of CAV1 in the malignant epithelial cells is accompanied by a loss of CAV1 in the tumor stroma, both facts that were correlated with higher Gleason scores, poor prognosis, and pronounced resistance to therapy particularly to radiotherapy (RT). However, it needs to be clarified whether inhibiting the CAV1 gain in the malignant prostate epithelium or limiting the loss of stromal CAV1 would be the better choice for improving PCa therapy, particularly for improving the response to RT; or whether ideally both processes need to be targeted. Concerning the first assumption, we investigated the RT response of LNCaP PCa cells following overexpression of different CAV1 mutants. While CAV1 overexpression generally caused an increased epithelial-to-mesenchymal phenotype in respective LNCaP cells, effects that were accompanied by increasing levels of the 5′-AMP-activated protein kinase (AMPK), a master regulator of cellular homeostasis, only wildtype CAV1 was able to increase the three-dimensional growth of LNCaP spheroids, particularly following RT. Both effects could be limited by an additional treatment with the SRC inhibitor dasatinib, finally resulting in radiosensitization. Using co-cultured (CAV1-expressing) fibroblasts as an approximation to the in vivo situation of early PCa it could be revealed that RT itself caused an activated, more tumor-promoting phenotype of stromal fibroblats with an increased an increased metabolic potential, that could not be limited by combined dasatinib treatment. Thus, targeting fibroblasts and/or limiting fibroblast activation, potentially by limiting the loss of stromal CAV1 seems to be absolute for inhibiting the resistance-promoting CAV1-dependent signals of the tumor stroma.
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Affiliation(s)
- Alina Wittka
- Institute of Cell Biology (Cancer Research), University of Duisburg-Essen, Medical Faculty Essen, Essen, Germany
| | - Julia Ketteler
- Institute of Cell Biology (Cancer Research), University of Duisburg-Essen, Medical Faculty Essen, Essen, Germany
| | - Lars Borgards
- Institute of Cell Biology (Cancer Research), University of Duisburg-Essen, Medical Faculty Essen, Essen, Germany
| | - Patrick Maier
- Department of Radiation Oncology, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Carsten Herskind
- Department of Radiation Oncology, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Verena Jendrossek
- Institute of Cell Biology (Cancer Research), University of Duisburg-Essen, Medical Faculty Essen, Essen, Germany
| | - Diana Klein
- Institute of Cell Biology (Cancer Research), University of Duisburg-Essen, Medical Faculty Essen, Essen, Germany
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7
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Zhang Y, Zhang X, Kong W, Wang S. Reconstitution of Caveolin-1 into Artificial Lipid Membrane: Characterization by Transmission Electron Microscopy and Solid-State Nuclear Magnetic Resonance. Molecules 2021; 26:molecules26206201. [PMID: 34684779 PMCID: PMC8539922 DOI: 10.3390/molecules26206201] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 10/09/2021] [Accepted: 10/11/2021] [Indexed: 12/26/2022] Open
Abstract
Caveolin-1 (CAV1), a membrane protein that is necessary for the formation and maintenance of caveolae, is a promising drug target for the therapy of various diseases, such as cancer, diabetes, and liver fibrosis. The biology and pathology of caveolae have been widely investigated; however, very little information about the structural features of full-length CAV1 is available, as well as its biophysical role in reshaping the cellular membrane. Here, we established a method, with high reliability and reproducibility, for the expression and purification of CAV1. Amyloid-like properties of CAV1 and its C-terminal peptide CAV1(168-178) suggest a structural basis for the short linear CAV1 assemblies that have been recently observed in caveolin polyhedral cages in Escherichia coli (E. coli). Reconstitution of CAV1 into artificial lipid membranes induces a caveolae-like membrane curvature. Structural characterization of CAV1 in the membrane by solid-state nuclear magnetic resonance (ssNMR) indicate that it is largely α-helical, with very little β-sheet content. Its scaffolding domain adopts a α-helical structure as identified by chemical shift analysis of threonine (Thr). Taken together, an in vitro model was developed for the CAV1 structural study, which will further provide meaningful evidences for the design and screening of bioactive compounds targeting CAV1.
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Affiliation(s)
- Yanli Zhang
- Department of Pharmacy, Qilu Hospital of Shandong University, Cheeloo College of Medicine, Jinan 250012, China;
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center, Omaha, NE 68198, USA;
| | - Xinyan Zhang
- Department of Pharmaceutical Sciences, University of Nebraska Medical Center, Omaha, NE 68198, USA;
| | - Wenru Kong
- School of Pharmaceutical Sciences, Shandong University, Jinan 250012, China;
| | - Shuqi Wang
- School of Pharmaceutical Sciences, Shandong University, Jinan 250012, China;
- Correspondence: ; Tel.: +86-0531-88382014
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8
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Structural Interplays in the Flexible N-Terminus and Scaffolding Domain of Human Membrane Protein Caveolin 3. MEMBRANES 2021; 11:membranes11020082. [PMID: 33499357 PMCID: PMC7912387 DOI: 10.3390/membranes11020082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 01/21/2021] [Accepted: 01/21/2021] [Indexed: 11/28/2022]
Abstract
Caveolins are critical for the formation of caveolae, which are small invaginations of the plasma membrane involved in a variety of biological processes. Caveolin 3 (Cav3), one of three caveolin isoforms, is an integral membrane protein mainly expressed in muscle tissues. Although various human diseases associated with Cav3 have been reported, structural characterization of Cav3 in the membrane has not been investigated in enough depth to understand the structure–function relationship. Here, using solution NMR, we characterized membrane association, structural communications, and molecular dynamics of the monomeric Cav3 in detergent micelle environment, particularly focused on the whole N-terminal part that is composed of the flexible N-terminus and the scaffolding domain. The results revealed a complicated structural interplay of the individual segments composing the whole N-terminal part, including the pH-dependent helical region, signature motif-like region, signature motif, and scaffolding domain. Collectively, the present study provides novel structural insights into the whole N-terminal part of Cav3 that plays important biological roles in cellular processes and diseases. In particular, given that several disease-related mutations are located at the whole N-terminal part of Cav3, the sophisticated communications in the whole N-terminal segments are likely to have relevance to the molecular basis of Cav3-related disease.
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9
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Zhang J, Yan D, He L, Zhang Q, Wen S, Liu P, Zhou H, Peng Y. Expression of Caveolin-1 Is Associated With Thyroid Function in Patients With Human Papillary Thyroid Carcinoma. Dose Response 2020; 18:1559325820919330. [PMID: 32313526 PMCID: PMC7160781 DOI: 10.1177/1559325820919330] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2019] [Revised: 03/12/2020] [Accepted: 03/20/2020] [Indexed: 11/22/2022] Open
Abstract
Objective: The aim of this study was to evaluate the levels of caveolin-1 in thyroid
follicular epithelial cells of papillary thyroid cancer, follicular thyroid
cancer, and nonmalignant thyroid nodule benign follicular adenoma, as well
as to explore the relationship between the levels of caveolin-1 and thyroid
function. Methods: Thirty cases of papillary thyroid cancer, 10 cases of follicular thyroid
cancer, 32 cases of nonmalignant thyroid nodule benign follicular adenoma,
and 30 controls were enrolled in this study. Caveolin-1 expression in tissue
specimens obtained from these cases was evaluated by immunohistochemistry
and Western blotting. Results: Caveolin-1 expression in thyroid epithelial cells of patients with papillary
thyroid cancer, particularly female patients, was significantly higher than
that in patients with follicular thyroid cancer and nonmalignant thyroid
nodule benign follicular adenoma (P < .005). Serum
thyroid-stimulating hormone (TSH) levels in the caveolin-1-positive
expression group were lower than that in the caveolin-1-negative expression
group, and the lowest expression of caveolin-1 was detected in tissues of
patients with Graves’ disease. The serum TSH level was associated with
caveolin-1 expression in thyroid epithelial cells. Conclusion: Caveolin-1 may participate in regulating thyroid function and is a potential
biomarker of follicular thyroid cancer.
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Affiliation(s)
- Jingyi Zhang
- Department of Endocrinology, Shanghai General Hospital of Nanjing Medical University, Shanghai, China.,Department of Immunology, Nanjing Medical University, Nanjing, China.,The Sixth Affiliated Hospital of Guangzhou Medical University, Qingyuan People's Hospital, Qingyuan, China
| | - Dongxia Yan
- Department of Pathology, Ma'anshan People's Hospital, Ma'anshan, China
| | - Lianping He
- College of Experience Industry, Anhui Polytechnic University, Wuhu, Anhui, China
| | - Qing Zhang
- Department of Pathology, Ma'anshan People's Hospital, Ma'anshan, China
| | - Shuang Wen
- Department of Immunology, Nanjing Medical University, Nanjing, China
| | - Peiyu Liu
- Department of Pharmacology, School of Basic Medical Science, Nanjing Medical University, Nanjing, China
| | - Hong Zhou
- Department of Immunology, Nanjing Medical University, Nanjing, China
| | - Yongde Peng
- Department of Endocrinology, Shanghai General Hospital of Nanjing Medical University, Shanghai, China
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10
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Rieth MD, Root KT, Glover KJ. Reconstitution of full-length human caveolin-1 into phospholipid bicelles: Validation by analytical ultracentrifugation. Biophys Chem 2020; 259:106339. [PMID: 32145579 PMCID: PMC8571804 DOI: 10.1016/j.bpc.2020.106339] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 01/31/2020] [Accepted: 02/24/2020] [Indexed: 11/26/2022]
Abstract
A significant hurdle in obtaining biophysical information on membrane proteins is developing a successful strategy for their reconstitution into a suitable membrane mimic. In particular, utilization of the more 'native-like' membrane mimics such as bicelles is generally more challenging than simple micellar solubilization. Caveolin-1, an integral membrane protein involved in membrane curvature, endocytosis, mechano-protection, and signal transduction, has been shown to be particularly recalcitrant to standard reconstitution protocols due to its highly hydrophobic characteristics. Herein we describe a robust method to incorporate recombinantly produced full-length caveolin-1 into bicelles at levels needed for biophysical experimentation. The benchmark of successful reconstitution is the obtainment of protein in a homogeneous state; therefore, we developed a validation procedure to monitor the success of the reconstitution using analytical ultracentrifugation of density-matched bicelles. Our findings indicated that our protocol produces a very homogeneous preparation of caveolin-1 associated with bicelles, and that caveolin-1 is highly α-helical (by circular dichroism spectroscopy). We believe that this methodology will serve as a general strategy to facilitate biophysical studies on membrane proteins.
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Affiliation(s)
- Monica D Rieth
- Department of Chemistry, Lehigh University, 6 E Packer Ave, Bethlehem, PA, USA
| | - Kyle T Root
- Department of Chemistry, Lehigh University, 6 E Packer Ave, Bethlehem, PA, USA
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11
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Bhattachan P, Rae J, Yu H, Jung W, Wei J, Parton RG, Dong B. Ascidian caveolin induces membrane curvature and protects tissue integrity and morphology during embryogenesis. FASEB J 2019; 34:1345-1361. [PMID: 31914618 DOI: 10.1096/fj.201901281r] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Revised: 10/30/2019] [Accepted: 11/14/2019] [Indexed: 01/20/2023]
Abstract
Cell morphology and tissue integrity are essential for embryogenesis. Caveolins are membrane proteins that induce the formation of surface pits called caveolae that serve as membrane reservoirs for cell and tissue protection during development. In vertebrates, caveolin 1 (Cav1) and caveolin 3 (Cav3) are required for caveola formation. However, the formation of caveola and the function of caveolins in invertebrates are largely unknown. In this study, three caveolins, Cav-a, Cav-b, and CavY, are identified in the genome of the invertebrate chordate Ciona spp. Based on phylogenetic analysis, Cav-a is found to be closely related to the vertebrate Cav1 and Cav3. In situ hybridization shows that Cav-a is expressed in Ciona embryonic notochord and muscle. Cell-free experiments, model cell culture systems, and in vivo experiments demonstrate that Ciona Cav-a has the ability to induce membrane curvature at the plasma membrane. Knockdown of Cav-a in Ciona embryos causes loss of invaginations in the plasma membrane and results in the failure of notochord elongation and lumenogenesis. Expression of a dominant-negative Cav-a point mutation causes cells to change shape and become displaced from the muscle and notochord to disrupt tissue integrity. Furthermore, we demonstrate that Cav-a vesicles show polarized trafficking and localize at the luminal membrane during notochord lumenogenesis. Taken together, these results show that the invertebrate chordate caveolin from Ciona plays crucial roles in tissue integrity and morphology by inducing membrane curvature and intracellular vesicle trafficking during embryogenesis.
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Affiliation(s)
- Punit Bhattachan
- Key Laboratory of Marine Genetics and Breeding, College of Marine Life Sciences, Ocean University of China, Qingdao, China.,Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China.,Institute of Evolution & Marine Biodiversity, Ocean University of China, Qingdao, China
| | - James Rae
- Institute for Molecular Bioscience, The University of Queensland, St. Lucia, QLD, Australia
| | - Haiyan Yu
- Key Laboratory of Marine Genetics and Breeding, College of Marine Life Sciences, Ocean University of China, Qingdao, China.,Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
| | - WooRam Jung
- Institute for Molecular Bioscience, The University of Queensland, St. Lucia, QLD, Australia
| | - Jiankai Wei
- Key Laboratory of Marine Genetics and Breeding, College of Marine Life Sciences, Ocean University of China, Qingdao, China.,Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China.,Institute of Evolution & Marine Biodiversity, Ocean University of China, Qingdao, China
| | - Robert G Parton
- Institute for Molecular Bioscience, The University of Queensland, St. Lucia, QLD, Australia.,Centre for Microscopy and Microanalysis, The University of Queensland, St. Lucia, QLD, Australia
| | - Bo Dong
- Key Laboratory of Marine Genetics and Breeding, College of Marine Life Sciences, Ocean University of China, Qingdao, China.,Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China.,Institute of Evolution & Marine Biodiversity, Ocean University of China, Qingdao, China
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12
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Secondary structure of caveolins: a mini review. Biochem Soc Trans 2019; 47:1489-1498. [DOI: 10.1042/bst20190375] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Revised: 08/19/2019] [Accepted: 08/27/2019] [Indexed: 01/28/2023]
Abstract
Abstract
Caveolae are 50–100 nm invaginations found within the plasma membrane of cells. Caveolae are involved in many processes that are essential for homeostasis, most notably endocytosis, mechano-protection, and signal transduction. Within these invaginations, the most important proteins are caveolins, which in addition to participating in the aforementioned processes are structural proteins responsible for caveolae biogenesis. When caveolin is misregulated or mutated, many disease states can arise which include muscular dystrophy, cancers, and heart disease. Unlike most integral membrane proteins, caveolin does not have a transmembrane orientation; instead, it is postulated to adopt an unusual topography where both the N- and C-termini lie on the cytoplasmic side of the membrane, and the hydrophobic span adopts an intramembrane loop conformation. While knowledge concerning the biology of caveolin has progressed apace, fundamental structural information has proven more difficult to obtain. In this mini-review, we curate as well as critically assess the structural data that have been obtained on caveolins to date in order to build a robust and compelling model of the caveolin secondary structure.
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13
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Plucinsky SM, Root KT, Glover KJ. Efficient solubilization and purification of highly insoluble membrane proteins expressed as inclusion bodies using perfluorooctanoic acid. Protein Expr Purif 2017; 143:34-37. [PMID: 29066155 DOI: 10.1016/j.pep.2017.10.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Revised: 10/14/2017] [Accepted: 10/19/2017] [Indexed: 02/06/2023]
Abstract
The purification of membrane proteins can be challenging due to their low solubility in conventional detergents and/or chaotropic solutions. The introduction of fusion systems that promote the formation of inclusion bodies has facilitated the over-expression of membrane proteins. In this protocol, we describe the use of perfluorooctanoic acid (PFOA) as an aid in the purification of highly hydrophobic membrane proteins expressed as inclusion bodies. The advantage of utilizing PFOA is threefold: first, PFOA is able to reliably solubilize inclusion bodies, second, PFOA is compatible with nickel affinity chromatography, and third, PFOA can be efficiently dialyzed away to produce a detergent free sample. To demonstrate the utility of employing PFOA, we expressed and purified a segment of the extremely hydrophobic membrane protein caveolin-1.
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Affiliation(s)
- Sarah M Plucinsky
- Department of Chemistry, Lehigh University, 6 E. Packer Ave, Bethlehem, PA 18015, USA
| | - Kyle T Root
- Department of Chemistry, Lock Haven University, 301 W. Church St, Lock Haven, PA 17745, USA
| | - Kerney Jebrell Glover
- Department of Chemistry, Lehigh University, 6 E. Packer Ave, Bethlehem, PA 18015, USA.
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14
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A pH-Mediated Topological Switch within the N-Terminal Domain of Human Caveolin-3. Biophys J 2017; 110:2475-2485. [PMID: 27276265 DOI: 10.1016/j.bpj.2016.05.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Revised: 04/27/2016] [Accepted: 05/02/2016] [Indexed: 11/22/2022] Open
Abstract
Caveolins mediate the formation of caveolae, which are small omega-shaped membrane invaginations involved in a variety of cellular processes. There are three caveolin isoforms, the third of which (Cav3) is expressed in smooth and skeletal muscles. Mutations in Cav3 cause a variety of human muscular diseases. In this work, we characterize the secondary structure, dynamics, and topology of the monomeric form of the full-length lipidated protein. Cav3 consists of a series of membrane-embedded or surface-associated helical elements connected by extramembrane connecting loops or disordered domains. Our results also reveal that the N-terminal domain undergoes a large scale pH-mediated topological rearrangement between soluble and membrane-anchored forms. Considering that roughly one-third of pathogenic mutations in Cav3 influence charged residues located in this domain, we hypothesize that this transition is likely to be relevant to the molecular basis of Cav3-linked diseases. These results provide insight into the structure of Cav3 and set the stage for mechanistic investigations of the effects of pathogenic mutations.
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15
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Han B, Copeland CA, Tiwari A, Kenworthy AK. Assembly and Turnover of Caveolae: What Do We Really Know? Front Cell Dev Biol 2016; 4:68. [PMID: 27446919 PMCID: PMC4921483 DOI: 10.3389/fcell.2016.00068] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Accepted: 06/13/2016] [Indexed: 11/13/2022] Open
Abstract
In addition to containing highly dynamic nanoscale domains, the plasma membranes of many cell types are decorated with caveolae, flask-shaped domains enriched in the structural protein caveolin-1 (Cav1). The importance of caveolae in numerous cellular functions and processes has become well-recognized, and recent years have seen dramatic advances in our understanding of how caveolae assemble and the mechanisms control the turnover of Cav1. At the same time, work from our lab and others have revealed that commonly utilized strategies such as overexpression and tagging of Cav1 have unexpectedly complex consequences on the trafficking and fate of Cav1. Here, we discuss the implications of these findings for current models of caveolae biogenesis and Cav1 turnover. In addition, we discuss how disease-associated mutants of Cav1 impact caveolae assembly and outline open questions in this still-emerging area.
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Affiliation(s)
- Bing Han
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine Nashville, TN, USA
| | - Courtney A Copeland
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine Nashville, TN, USA
| | - Ajit Tiwari
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine Nashville, TN, USA
| | - Anne K Kenworthy
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of MedicineNashville, TN, USA; Department of Cell and Developmental Biology, Vanderbilt University School of MedicineNashville, TN, USA; Epithelial Biology Program, Vanderbilt University School of MedicineNashville, TN, USA; Chemical and Physical Biology Program, Vanderbilt UniversityNashville, TN, USA
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16
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Root KT, Glover KJ. Reconstitution and spectroscopic analysis of caveolin-1 residues 62-178 reveals that proline 110 governs its structure and solvent exposure. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1858:682-8. [PMID: 26775739 DOI: 10.1016/j.bbamem.2016.01.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Revised: 12/04/2015] [Accepted: 01/06/2016] [Indexed: 12/21/2022]
Abstract
Caveolin-1 is a membrane protein that possesses an unusual topology where both N- and C-termini are cytoplasmic as a result of a membrane-embedded turn. In particular, proline 110 has been postulated to be the linchpin of this unusual motif. Using a caveolin-1 construct (residues 62-178) reconstituted into dodecylphosphocholine micelles with and without a cholesterol mimic, the changes that occurred upon P110A mutation were probed. Using far UV circular dichroism spectroscopy it was shown that cholesterol attenuated the helicity of caveolin-1, and that mutation of P110 to alanine caused a significant increase in the α-helicity of the protein. Near UV circular dichroism spectroscopy showed significant changes in structure and/or environment upon mutation that again were modulated by the presence of cholesterol. Stern-Volmer quenching and λ(max) analysis of tryptophan residues showed that the proline mutation caused W85 to become more exposed, W98 and W115 to become less exposed, and W128 showed no change. This finding provided evidence that regions proximal and far away from the proline are buried differentially upon its mutation and therefore this residue is strongly tied to maintaining the hydrophobic coverage along the caveolin-1 sequence. In the presence of cholesterol, the accessibilities of the two tryptophan residues that proceeded position 110 were altered much more significantly upon P110A mutation than the two tryptophans aft P110. Overall, this work provides strong evidence that proline 110 is critical for maintaining both the structure and hydrophobic coverage of caveolin-1 and that cholesterol also plays a significant role in modulating these parameters.
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Affiliation(s)
- Kyle T Root
- Department of Chemistry, Lehigh University, 6 E. Packer Ave., Bethlehem, PA 18015, USA
| | - Kerney Jebrell Glover
- Department of Chemistry, Lehigh University, 6 E. Packer Ave., Bethlehem, PA 18015, USA.
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17
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Ariotti N, Rae J, Leneva N, Ferguson C, Loo D, Okano S, Hill MM, Walser P, Collins BM, Parton RG. Molecular Characterization of Caveolin-induced Membrane Curvature. J Biol Chem 2015; 290:24875-90. [PMID: 26304117 DOI: 10.1074/jbc.m115.644336] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Indexed: 01/07/2023] Open
Abstract
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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Affiliation(s)
- Nicholas Ariotti
- From the University of Queensland, Institute for Molecular Bioscience, Queensland 4072, Australia
| | - James Rae
- From the University of Queensland, Institute for Molecular Bioscience, Queensland 4072, Australia
| | - Natalya Leneva
- From the University of Queensland, Institute for Molecular Bioscience, Queensland 4072, Australia
| | - Charles Ferguson
- From the University of Queensland, Institute for Molecular Bioscience, Queensland 4072, Australia
| | - Dorothy Loo
- The University of Queensland Diamantina Institute, The University of Queensland, Translational Research Institute, Brisbane, Queensland,Australia, and
| | - Satomi Okano
- From the University of Queensland, Institute for Molecular Bioscience, Queensland 4072, Australia
| | - Michelle M Hill
- The University of Queensland Diamantina Institute, The University of Queensland, Translational Research Institute, Brisbane, Queensland,Australia, and
| | - Piers Walser
- From the University of Queensland, Institute for Molecular Bioscience, Queensland 4072, Australia
| | - Brett M Collins
- From the University of Queensland, Institute for Molecular Bioscience, Queensland 4072, Australia
| | - Robert G Parton
- From the University of Queensland, Institute for Molecular Bioscience, Queensland 4072, Australia, the University of Queensland, Centre for Microscopy and Microanalysis, Brisbane, Queensland 4072, Australia
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18
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Root KT, Plucinsky SM, Glover KJ. Recent progress in the topology, structure, and oligomerization of caveolin: a building block of caveolae. CURRENT TOPICS IN MEMBRANES 2015; 75:305-36. [PMID: 26015287 DOI: 10.1016/bs.ctm.2015.03.007] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Caveolae are cholesterol-rich plasma membrane invaginations that are found in a plethora of cell types. They play many roles including signal transduction, endocytosis, and mechanoprotection. The most critical protein in caveolae is the integral membrane protein, caveolin, which has been shown to be necessary for caveolae formation, and governs the major functions attributed to caveolae. Caveolin is postulated to act as a scaffold in the high molecular weight striated coat that surrounds the caveolar bulb, stabilizing it. Caveolin interacts, both directly and indirectly, with a large number of signaling molecules, and presides over the endocytosis of molecular cargo by caveolae. However, many of the key biophysical aspects of the caveolin protein, its structure, topology, and oligomeric behavior, are just beginning to come to light. Herein is an up-to-date summary and critique of the progress that has been made in understanding caveolin on a molecular and atomic level.
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Affiliation(s)
- Kyle T Root
- Department of Chemistry, Lehigh University, Bethlehem, PA, USA
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19
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Han B, Tiwari A, Kenworthy AK. Tagging strategies strongly affect the fate of overexpressed caveolin-1. Traffic 2015; 16:417-38. [PMID: 25639341 PMCID: PMC4440517 DOI: 10.1111/tra.12254] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2014] [Revised: 12/24/2014] [Accepted: 12/24/2014] [Indexed: 01/01/2023]
Abstract
Caveolin-1 (Cav1) is the primary scaffolding protein of caveolae, flask-shaped invaginations of the plasma membrane thought to function in endocytosis, mechanotransduction, signaling and lipid homeostasis. A significant amount of our current knowledge about caveolins and caveolae is derived from studies of transiently overexpressed, C-terminally tagged caveolin proteins. However, how different tags affect the behavior of ectopically expressed Cav1 is still largely unknown. To address this question, we performed a comparative analysis of the subcellular distribution, oligomerization state and detergent resistance of transiently overexpressed Cav1 labeled with three different C-terminal tags (EGFP, mCherry and myc). We show that addition of fluorescent protein tags enhances the aggregation and/or degradation of both wild-type Cav1 and an oligomerization defective P132L mutant. Strikingly, complexes formed by overexpressed Cav1 fusion proteins excluded endogenous Cav1 and Cav2, and the properties of native caveolins were largely preserved even when abnormal aggregates were present in cells. These findings suggest that differences in tagging strategies may be a source of variation in previously published studies of Cav1 and that overexpressed Cav1 may exert functional effects outside of caveolae. They also highlight the need for a critical re-evaluation of current knowledge based on transient overexpression of tagged Cav1.
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Affiliation(s)
- Bing Han
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of MedicineNashville, TN, USA
| | - Ajit Tiwari
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of MedicineNashville, TN, USA
| | - Anne K Kenworthy
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of MedicineNashville, TN, USA
- Department of Cell and Developmental Biology, Vanderbilt University School of MedicineNashville, TN, USA
- Epithelial Biology Program, Vanderbilt University School of MedicineNashville, TN, USA
- Chemical and Physical Biology Program, Vanderbilt UniversityNashville, TN, USA
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20
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Yang G, Dong Z, Xu H, Wang C, Li H, Li Z, Li F. Structural study of caveolin-1 intramembrane domain by circular dichroism and nuclear magnetic resonance. Biopolymers 2015; 104:11-20. [DOI: 10.1002/bip.22597] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2014] [Revised: 10/22/2014] [Accepted: 11/30/2014] [Indexed: 01/08/2023]
Affiliation(s)
- Guanhua Yang
- State Key Laboratory of Supramolecular Structure and Materials; Jilin University; Changchun 130012 People's Republic of China
| | - Zhe Dong
- State Key Laboratory of Supramolecular Structure and Materials; Jilin University; Changchun 130012 People's Republic of China
| | - Haoran Xu
- Key Laboratory for Molecular Enzymology & Engineering; The Ministry of Education, Jilin University; Changchun 130012 People's Republic of China
| | - Chunyu Wang
- State Key Laboratory of Supramolecular Structure and Materials; Jilin University; Changchun 130012 People's Republic of China
| | - Haichao Li
- Key Laboratory for Molecular Enzymology & Engineering; The Ministry of Education, Jilin University; Changchun 130012 People's Republic of China
| | - Zhengqiang Li
- Key Laboratory for Molecular Enzymology & Engineering; The Ministry of Education, Jilin University; Changchun 130012 People's Republic of China
| | - Fei Li
- State Key Laboratory of Supramolecular Structure and Materials; Jilin University; Changchun 130012 People's Republic of China
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21
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Yang G, Xu H, Li Z, Li F. Interactions of caveolin-1 scaffolding and intramembrane regions containing a CRAC motif with cholesterol in lipid bilayers. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2014; 1838:2588-99. [PMID: 24998359 DOI: 10.1016/j.bbamem.2014.06.018] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2014] [Revised: 06/13/2014] [Accepted: 06/22/2014] [Indexed: 11/27/2022]
Abstract
Caveolin-1 is a major structural protein of caveolae and specifically binds cholesterol (Chol). The caveolin scaffolding domain is thought to be involved in caveolin-Chol interaction through the sequence V94-T-K-Y-W-F-Y-R101, a motif that matches a cholesterol recognition amino-acid consensus (CRAC). In the present work, three CRAC-containing peptides, corresponding to caveolin-1 94-101, 82-101 and 93-126, were tested to study the role of the CRAC motif in the caveolin-Chol interaction in 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) bilayers using differential scanning calorimetry (DSC), fluorescence and circular dichroism (CD). The Y97I substituents of the three peptides and one peptide segment corresponding to caveolin-1 101-126 that excludes the CRAC motif were also tested for comparison. Our results showed the potency of these CRAC-containing peptides in sequestering Chol into domains and the enhanced role of the intramembrane domain and scaffolding domain for the potency. Of the three CRAC-containing peptides, the peptide 93-126 was particularly effective in promoting Chol segregation, while the peptide 82-101 was less potent in promoting the formation of domains than the peptide 93-126, but was more potent than the peptide 94-101. The domain partition of DPPC/Chol bilayers was not observed in the presence of the peptide 101-126, in contrast to the case in the presence of the peptide 93-126 at the same concentrations of peptide and Chol. The potency of the CRAC motif in Chol segregation was lowered by the Y97I mutation. The difference in structure may be a factor that contributes to different effects of these peptides on the distribution of Chol in the lipid membrane.
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Affiliation(s)
- Guanhua Yang
- State Key Laboratory of Supramolecular Structure and Materials, Jilin University, Changchun, 130012, PR China
| | - Haoran Xu
- Key Laboratory for Molecular Enzymology & Engineering, The Ministry of Education, Jilin University, Changchun 130012, PR China
| | - Zhengqiang Li
- Key Laboratory for Molecular Enzymology & Engineering, The Ministry of Education, Jilin University, Changchun 130012, PR China
| | - Fei Li
- State Key Laboratory of Supramolecular Structure and Materials, Jilin University, Changchun, 130012, PR China.
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22
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Kim JH, Peng D, Schlebach JP, Hadziselimovic A, Sanders CR. Modest effects of lipid modifications on the structure of caveolin-3. Biochemistry 2014; 53:4320-2. [PMID: 24960539 PMCID: PMC4100780 DOI: 10.1021/bi5005238] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
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Caveolin-3
(Cav3) is an unconventional membrane protein that serves
as a critical scaffolding hub in caveolae and is genetically linked
to various muscle disorders. In this work, we report the expression,
purification, and characterization of full-length human Cav3. To mimic
the palmitoylation of endogenous Cav3, we developed a generally applicable
approach to covalently attached thioalkyl chains at natively modified
cysteine residues. Nuclear magnetic resonance measurements indicate
that lipidation exerts only a modest and local effect on the Cav3
structure, with little impact on the structures of the N-terminal
domain, the scaffolding domain, and the extreme C-terminus.
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Affiliation(s)
- Ji-Hun Kim
- Department of Biochemistry and Center for Structural Biology, Vanderbilt University School of Medicine , Nashville, Tennessee 37232, United States
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23
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Hanson CA, Drake KR, Baird MA, Han B, Kraft LJ, Davidson MW, Kenworthy AK. Overexpression of caveolin-1 is sufficient to phenocopy the behavior of a disease-associated mutant. Traffic 2013; 14:663-77. [PMID: 23469926 DOI: 10.1111/tra.12066] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2012] [Revised: 03/05/2013] [Accepted: 03/07/2013] [Indexed: 12/30/2022]
Abstract
Mutations and alterations in caveolin-1 expression levels have been linked to a number of human diseases. How misregulation of caveolin-1 contributes to disease is not fully understood, but has been proposed to involve the intracellular accumulation of mutant forms of the protein. To better understand the molecular basis for trafficking defects that trap caveolin-1 intracellularly, we compared the properties of a GFP-tagged version of caveolin-1 P132L, a mutant form of caveolin-1 previously linked to breast cancer, with wild-type caveolin-1. Unexpectedly, wild-type caveolin-1-GFP also accumulated intracellularly, leading us to examine the mechanisms underlying the abnormal localization of the wild type and mutant protein in more detail. We show that both the nature of the tag and cellular context impact the subcellular distribution of caveolin-1, demonstrate that even the wild-type form of caveolin-1 can function as a dominant negative under some conditions, and identify specific conformation changes associated with incorrectly targeted forms of the protein. In addition, we find intracellular caveolin-1 is phosphorylated on Tyr14, but phosphorylation is not required for mistrafficking of the protein. These findings identify novel properties of mistargeted forms of caveolin-1 and raise the possibility that common trafficking defects underlie diseases associated with overexpression and mutations in caveolin-1.
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Affiliation(s)
- Caroline A Hanson
- Department of Molecular Physiology & Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
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24
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Senetta R, Stella G, Pozzi E, Sturli N, Massi D, Cassoni P. Caveolin-1 as a promoter of tumour spreading: when, how, where and why. J Cell Mol Med 2013; 17:325-36. [PMID: 23521716 PMCID: PMC3823014 DOI: 10.1111/jcmm.12030] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2012] [Accepted: 01/15/2013] [Indexed: 11/29/2022] Open
Abstract
Caveolae are non-clathrin invaginations of the plasma membrane in most cell types; they are involved in signalling functions and molecule trafficking, thus modulating several biological functions, including cell growth, apoptosis and angiogenesis. The major structural protein in caveolae is caveolin-1, which is known to act as a key regulator in cancer onset and progression through its role as a tumour suppressor. Caveolin-1 can also promote cell proliferation, survival and metastasis as well as chemo- and radioresistance. Here, we discuss recent findings and novel concepts that support a role for caveolin-1 in cancer development and its distant spreading. We also address the potential application of caveolin-1 in tumour therapy and diagnosis.
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Affiliation(s)
- Rebecca Senetta
- Department of Medical Sciences, University of Turin, Turin, Italy
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