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Tabbasum VG, Cooper DMF. Structural and Functional Determinants of AC8 Trafficking, Targeting and Responsiveness in Lipid Raft Microdomains. J Membr Biol 2019; 252:159-172. [PMID: 30746562 PMCID: PMC6556161 DOI: 10.1007/s00232-019-00060-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Accepted: 01/21/2019] [Indexed: 01/01/2023]
Abstract
The fidelity of cAMP in controlling numerous cellular functions rests crucially on the precise organization of cAMP microdomains that are sustained by the scaffolding properties of adenylyl cyclase. Earlier studies suggested that AC8 enriches in lipid rafts where it interacts with cytoskeletal elements. However, these are not stable structures and little is known about the dynamics of AC8 secretion and its interactions. The present study addresses the role of the cytoskeleton in maintaining the AC8 microenvironment, particularly in the context of the trafficking route of AC8 and its interaction with caveolin1. Here, biochemical and live-cell imaging approaches expose a complex, dynamic interaction between AC8 and caveolin1 that affects AC8 processing, targeting and responsiveness in plasma membrane lipid rafts. Site-directed mutagenesis and pharmacological approaches reveal that AC8 is processed with complex N-glycans and associates with lipid rafts en route to the plasma membrane. A dynamic picture emerges of the trafficking and interactions of AC8 while travelling to the plasma membrane, which are key to the organization of the AC8 microdomain.
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Affiliation(s)
- Valentina G Tabbasum
- Department of Pharmacology, University of Cambridge, Tennis Court Rd., Cambridge, CB2 1PD, UK
| | - Dermot M F Cooper
- Department of Pharmacology, University of Cambridge, Tennis Court Rd., Cambridge, CB2 1PD, UK.
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2
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Yang R, Wang J, Zhou Z, Qi S, Ruan S, Lin Z, Xin Q, Lin Y, Chen X, Xie J. Role of caveolin-1 in epidermal stem cells during burn wound healing in rats. Dev Biol 2018; 445:271-279. [PMID: 30476483 DOI: 10.1016/j.ydbio.2018.11.015] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Revised: 11/22/2018] [Accepted: 11/22/2018] [Indexed: 12/24/2022]
Abstract
Local transplantation of stem cells has therapeutic effects on skin damage but cannot provide satisfactory wound healing. Studies on the mechanisms underlying the therapeutic effects of stem cells on skin wound healing will be needed. Hence, in the present study, we explored the role of Caveolin-1 in epidermal stem cells (EpiSCs) in the modulation of wound healing. We first isolated EpiSCs from mouse skin tissues and established stable EpiSCs with overexpression of Caveolin-1 using a lentiviral construct. We then evaluated the epidermal growth factor (EGF)-induced cell proliferation ability using cell counting Kit-8 (CCK-8) assay and assessed EpiSC pluripotency by examining Nanog mRNA levels in EpiSCs. Furthermore, we treated mice with skin burn injury using EpiSCs with overexpression of Caveolin-1. Histological examinations were conducted to evaluate re-epithelialization, wound scores, cell proliferation and capillary density in wounds. We found that overexpression of Caveolin-1 in EpiSCs promoted EGF-induced cell proliferation ability and increased wound closure in a mouse model of skin burn injury. Histological evaluation demonstrated that overexpression of Caveolin-1 in EpiSCs promoted re-epithelialization in wounds, enhanced cellularity, and increased vasculature, as well as increased wound scores. Taken together, our results suggested that Caveolin-1 expression in the EpiSCs play a critical role in the regulation of EpiSC proliferation ability and alteration of EpiSC proliferation ability may be an effective approach in promoting EpiSC-based therapy in skin wound healing.
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Affiliation(s)
- Ronghua Yang
- Department of Burn Surgery, the First People's Hospital of Foshan, Foshan 528000, Guangdong, China
| | - Jingru Wang
- Department of Burn Surgery, the First People's Hospital of Foshan, Foshan 528000, Guangdong, China
| | - Ziheng Zhou
- Department of Burn Surgery, First Affiliated Hospital of Sun Yat-Sen University, Guangzhou 510000, Guangdong, China
| | - Shaohai Qi
- Department of Burn Surgery, First Affiliated Hospital of Sun Yat-Sen University, Guangzhou 510000, Guangdong, China
| | - Shubin Ruan
- Department of Burn Surgery, the First People's Hospital of Foshan, Foshan 528000, Guangdong, China
| | - Zepeng Lin
- Department of Burn Surgery, the First People's Hospital of Foshan, Foshan 528000, Guangdong, China
| | - Qi Xin
- Department of Burn Surgery, the First People's Hospital of Foshan, Foshan 528000, Guangdong, China
| | - Yan Lin
- Department of Burn Surgery, the First People's Hospital of Foshan, Foshan 528000, Guangdong, China
| | - Xiaodong Chen
- Department of Burn Surgery, the First People's Hospital of Foshan, Foshan 528000, Guangdong, China.
| | - Julin Xie
- Department of Burn Surgery, First Affiliated Hospital of Sun Yat-Sen University, Guangzhou 510000, Guangdong, China.
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Wang J, Bai Y, Zhao X, Ru J, Kang N, Tian T, Tang L, An Y, Li P. oxLDL-mediated cellular senescence is associated with increased NADPH oxidase p47phox recruitment to caveolae. Biosci Rep 2018; 38:BSR20180283. [PMID: 29695496 PMCID: PMC5997791 DOI: 10.1042/bsr20180283] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Revised: 04/05/2018] [Accepted: 04/24/2018] [Indexed: 01/26/2023] Open
Abstract
Atherosclerosis develops as a consequence of inflammation and cell senescence. In critical factors involved in the atherosclerotic changes, reactive oxygen species (ROS) generation is considered a leading cause. While NADPH oxidases, particularly NOX2, are the main sources of ROS, how they are regulated in the disease is incompletely understood. In addition, how caveolae, the membrane structure implicated in oxLDL deposition under vascular endothelia, is involved in the oxLDL-mediated ROS production remains mostly elusive. We report here that macrophages exposed to oxLDL up-regulate its caveolin-1 expression, and the latter in turn up-regulates NOX2 p47phox level. This combination effect results in increased cellular senescence. Interestingly, oxLDL treatment causes the p47phox residing in the cytosol to translocate to the caveolae. Immunoprecipitation assays confirms that cavelin-1 is in high degree association with p47phox. These results suggest caveolin-1 may serve as the membrane target for p47phox and as a switch for ROS production following oxLDL exposure. Our results reveal a previously unknown molecular event in oxLDL-mediated cellular ageing, and may provide a target for clinical intervention for atherosclerosis.
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Affiliation(s)
- Jing Wang
- Department of Geriatrics, Beijing Chaoyang Hospital Affiliated to Capital Medical University, Beijing 100043, China
| | - Yuzhi Bai
- Department of Geriatrics, Beijing Chaoyang Hospital Affiliated to Capital Medical University, Beijing 100043, China
| | - Xia Zhao
- Department of Geriatrics, Beijing Chaoyang Hospital Affiliated to Capital Medical University, Beijing 100043, China
| | - Jing Ru
- Department of Geriatrics, Beijing Chaoyang Hospital Affiliated to Capital Medical University, Beijing 100043, China
| | - Ning Kang
- Institute for Immunology, Department of Basic Medical Sciences, School of Medicine, Tsinghua-Peking Joint Center for Life Sciences, Tsinghua University, Beijing 100084, China
| | - Tian Tian
- Department of Geriatrics, Beijing Chaoyang Hospital Affiliated to Capital Medical University, Beijing 100043, China
| | - Liying Tang
- Department of Geriatrics, Beijing Chaoyang Hospital Affiliated to Capital Medical University, Beijing 100043, China
| | - Yun An
- Department of Geriatrics, Beijing Chaoyang Hospital Affiliated to Capital Medical University, Beijing 100043, China
| | - Pei Li
- Department of Geriatrics, Beijing Chaoyang Hospital Affiliated to Capital Medical University, Beijing 100043, China
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4
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Spencer A, Yu L, Guili V, Reynaud F, Ding Y, Ma J, Jullien J, Koubi D, Gauthier E, Cluet D, Falk J, Castellani V, Yuan C, Rudkin BB. Nerve Growth Factor Signaling from Membrane Microdomains to the Nucleus: Differential Regulation by Caveolins. Int J Mol Sci 2017; 18:E693. [PMID: 28338624 PMCID: PMC5412279 DOI: 10.3390/ijms18040693] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2016] [Revised: 03/08/2017] [Accepted: 03/13/2017] [Indexed: 11/16/2022] Open
Abstract
Membrane microdomains or "lipid rafts" have emerged as essential functional modules of the cell, critical for the regulation of growth factor receptor-mediated responses. Herein we describe the dichotomy between caveolin-1 and caveolin-2, structural and regulatory components of microdomains, in modulating proliferation and differentiation. Caveolin-2 potentiates while caveolin-1 inhibits nerve growth factor (NGF) signaling and subsequent cell differentiation. Caveolin-2 does not appear to impair NGF receptor trafficking but elicits prolonged and stronger activation of MAPK (mitogen-activated protein kinase), Rsk2 (ribosomal protein S6 kinase 2), and CREB (cAMP response element binding protein). In contrast, caveolin-1 does not alter initiation of the NGF signaling pathway activation; rather, it acts, at least in part, by sequestering the cognate receptors, TrkA and p75NTR, at the plasma membrane, together with the phosphorylated form of the downstream effector Rsk2, which ultimately prevents CREB phosphorylation. The non-phosphorylatable caveolin-1 serine 80 mutant (S80V), no longer inhibits TrkA trafficking or subsequent CREB phosphorylation. MC192, a monoclonal antibody towards p75NTR that does not block NGF binding, prevents exit of both NGF receptors (TrkA and p75NTR) from lipid rafts. The results presented herein underline the role of caveolin and receptor signaling complex interplay in the context of neuronal development and tumorigenesis.
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MESH Headings
- Animals
- Antibodies, Monoclonal/immunology
- CREB-Binding Protein/metabolism
- Caveolin 1/antagonists & inhibitors
- Caveolin 1/genetics
- Caveolin 1/metabolism
- Caveolin 2/antagonists & inhibitors
- Caveolin 2/genetics
- Caveolin 2/metabolism
- Cell Differentiation/drug effects
- Cell Nucleus/metabolism
- Cells, Cultured
- Ganglia, Spinal/cytology
- Ganglia, Spinal/metabolism
- Membrane Microdomains/metabolism
- Mice
- Nerve Growth Factor/pharmacology
- Nerve Tissue Proteins
- PC12 Cells
- Phosphorylation/drug effects
- Protein Binding
- Protein Transport/drug effects
- RNA Interference
- RNA, Small Interfering/metabolism
- Rats
- Receptor, Nerve Growth Factor/metabolism
- Receptor, trkA/chemistry
- Receptor, trkA/immunology
- Receptor, trkA/metabolism
- Receptors, Growth Factor
- Receptors, Nerve Growth Factor/chemistry
- Receptors, Nerve Growth Factor/immunology
- Receptors, Nerve Growth Factor/metabolism
- Ribosomal Protein S6 Kinases, 90-kDa/metabolism
- Signal Transduction/drug effects
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Affiliation(s)
- Ambre Spencer
- East China Normal University, Key Laboratory of Brain Functional Genomics of the Ministry of Education of PR China, Joint Laboratory of Neuropathogenesis, ECNU, ENS Lyon, CNRS, Shanghai 200062, China.
- Univ. Lyon, Ecole normale supérieure de Lyon, Université Claude Bernard Lyon 1, CNRS, Differentiation & Cell Cycle Group, Laboratoire de Biologie Moléculaire de la Cellule, UMR5239, 69007 Lyon, France.
- East China Normal University, School of Life Sciences, Laboratory of Molecular and Cellular Neurophysiology, Shanghai 200062, China.
| | - Lingli Yu
- East China Normal University, Key Laboratory of Brain Functional Genomics of the Ministry of Education of PR China, Joint Laboratory of Neuropathogenesis, ECNU, ENS Lyon, CNRS, Shanghai 200062, China.
- Univ. Lyon, Ecole normale supérieure de Lyon, Université Claude Bernard Lyon 1, CNRS, Differentiation & Cell Cycle Group, Laboratoire de Biologie Moléculaire de la Cellule, UMR5239, 69007 Lyon, France.
- East China Normal University, School of Life Sciences, Laboratory of Molecular and Cellular Neurophysiology, Shanghai 200062, China.
| | - Vincent Guili
- Univ. Lyon, Ecole normale supérieure de Lyon, Université Claude Bernard Lyon 1, CNRS, Differentiation & Cell Cycle Group, Laboratoire de Biologie Moléculaire de la Cellule, UMR5239, 69007 Lyon, France.
| | - Florie Reynaud
- Univ. Lyon, Université Claude Bernard Lyon 1, CNRS, CGphiMC UMR5534, 69622 Villeurbanne Cedex, France.
| | - Yindi Ding
- East China Normal University, Key Laboratory of Brain Functional Genomics of the Ministry of Education of PR China, Joint Laboratory of Neuropathogenesis, ECNU, ENS Lyon, CNRS, Shanghai 200062, China.
- Univ. Lyon, Ecole normale supérieure de Lyon, Université Claude Bernard Lyon 1, CNRS, Differentiation & Cell Cycle Group, Laboratoire de Biologie Moléculaire de la Cellule, UMR5239, 69007 Lyon, France.
- East China Normal University, School of Life Sciences, Laboratory of Molecular and Cellular Neurophysiology, Shanghai 200062, China.
| | - Ji Ma
- East China Normal University, Key Laboratory of Brain Functional Genomics of the Ministry of Education of PR China, Joint Laboratory of Neuropathogenesis, ECNU, ENS Lyon, CNRS, Shanghai 200062, China.
- East China Normal University, School of Life Sciences, Laboratory of Molecular and Cellular Neurophysiology, Shanghai 200062, China.
| | - Jérôme Jullien
- Univ. Lyon, Ecole normale supérieure de Lyon, Université Claude Bernard Lyon 1, CNRS, Differentiation & Cell Cycle Group, Laboratoire de Biologie Moléculaire de la Cellule, UMR5239, 69007 Lyon, France.
| | - David Koubi
- Univ. Lyon, Ecole normale supérieure de Lyon, Université Claude Bernard Lyon 1, CNRS, Differentiation & Cell Cycle Group, Laboratoire de Biologie Moléculaire de la Cellule, UMR5239, 69007 Lyon, France.
| | - Emmanuel Gauthier
- Univ. Lyon, Ecole normale supérieure de Lyon, Université Claude Bernard Lyon 1, CNRS, Differentiation & Cell Cycle Group, Laboratoire de Biologie Moléculaire de la Cellule, UMR5239, 69007 Lyon, France.
| | - David Cluet
- East China Normal University, Key Laboratory of Brain Functional Genomics of the Ministry of Education of PR China, Joint Laboratory of Neuropathogenesis, ECNU, ENS Lyon, CNRS, Shanghai 200062, China.
- Univ. Lyon, Ecole normale supérieure de Lyon, Université Claude Bernard Lyon 1, CNRS, Differentiation & Cell Cycle Group, Laboratoire de Biologie Moléculaire de la Cellule, UMR5239, 69007 Lyon, France.
| | - Julien Falk
- Univ. Lyon, Université Claude Bernard Lyon 1, CNRS, CGphiMC UMR5534, 69622 Villeurbanne Cedex, France.
| | - Valérie Castellani
- Univ. Lyon, Université Claude Bernard Lyon 1, CNRS, CGphiMC UMR5534, 69622 Villeurbanne Cedex, France.
| | - Chonggang Yuan
- East China Normal University, Key Laboratory of Brain Functional Genomics of the Ministry of Education of PR China, Joint Laboratory of Neuropathogenesis, ECNU, ENS Lyon, CNRS, Shanghai 200062, China.
- East China Normal University, School of Life Sciences, Laboratory of Molecular and Cellular Neurophysiology, Shanghai 200062, China.
| | - Brian B Rudkin
- East China Normal University, Key Laboratory of Brain Functional Genomics of the Ministry of Education of PR China, Joint Laboratory of Neuropathogenesis, ECNU, ENS Lyon, CNRS, Shanghai 200062, China.
- Univ. Lyon, Ecole normale supérieure de Lyon, Université Claude Bernard Lyon 1, CNRS, Differentiation & Cell Cycle Group, Laboratoire de Biologie Moléculaire de la Cellule, UMR5239, 69007 Lyon, France.
- Univ. Lyon, Université Claude Bernard Lyon 1, Inserm, Stem Cell and Brain Research Institute U1208, 69500 Bron, France.
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5
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Abstract
PURPOSE OF REVIEW Diabetic nephropathy, a major microvascular complication of diabetes and the most common cause of end-stage renal disease, is characterized by prominent accumulation of extracellular matrix. The membrane microdomains caveolae, and their integral protein caveolin-1, play critical roles in the regulation of signal transduction. In this review we discuss current knowledge of the contribution of caveolin-1/caveolae to profibrotic signaling and the pathogenesis of diabetic kidney disease, and assess its potential as a therapeutic target. RECENT FINDINGS Caveolin (cav)-1 is key to facilitating profibrotic signal transduction induced by several stimuli known to be pathogenic in diabetic nephropathy, including the most prominent factors hyperglycemia and angiotensin II. Phosphorylation of cav-1 on Y14 is an important regulator of these responses. In vivo studies support a pathogenic role for caveolae in the progression of diabetic nephropathy. Targeting caveolin-1/caveolae would enable inhibition of multiple profibrotic pathways, representing a novel and potentially potent therapeutic option for diabetic nephropathy.
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Affiliation(s)
- Richard Van Krieken
- Department of Medicine, Division of Nephrology, St. Joseph's Hospital, McMaster University, 50 Charlton Ave E, T3311, Hamilton, ON, L8N 4A6, Canada
| | - Joan C Krepinsky
- Department of Medicine, Division of Nephrology, St. Joseph's Hospital, McMaster University, 50 Charlton Ave E, T3311, Hamilton, ON, L8N 4A6, Canada.
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Hirsch GE, Parisi MM, Martins LAM, Andrade CMB, Barbé-Tuana FM, Guma FTCR. γ-Oryzanol reduces caveolin-1 and PCGEM1 expression, markers of aggressiveness in prostate cancer cell lines. Prostate 2015; 75:783-97. [PMID: 25619388 DOI: 10.1002/pros.22960] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Accepted: 12/09/2014] [Indexed: 12/27/2022]
Abstract
BACKGROUND Prostate cancer is a leading cause of death among men due to the limited number of treatment strategies available for advanced disease. γ-oryzanol is a component of rice bran, rich in phytosterols, known for its antioxidant, anti-carcinogenic and endocrinological effects. It is known that γ-oryzanol may affect prostate cancer cells through the down regulation of the antioxidant genes and that phytosterols have anti-proliferative and apoptotic effects. There are evidences showing that some of the components of γ-oryzanol can modulate genes involved in the development and progression of prostate cancer, as caveolin-1 (Cav-1) and prostate specific androgen-regulated gene (PCGEM1). METHODS To determine the effects of γ-oryzanol on prostate cancer cell survival we evaluated the cell viability and biomass by MTT and sulforhodamine B assays, respectively. Cell death, cell cycle and pERK1/2 activity were assessed by flow cytometry. The changes in gene expression involved in the survival and progression of prostate cancer cav-1 and PCGEM1 genes were evaluated by quantitative real time reverse transcriptase polymerase chain reaction (RT-PCR) and cav-1 protein by immunofluorescence followed by confocal microscopy analysis. RESULTS We found that γ-oryzanol decreases cell viability and culture biomass by apoptosis and/or necrosis death in androgen unresponsive (PC3 and DU145) and responsive (LNCaP) cell lines, and signals through pERK1/2 in LNCaP and DU145 cells. γ-oryzanol also appears to block cell cycle progression at the G2/M in PC3 and LNCaP cells and at G0/G1 in DU145 cells. These effects were accompanied by a down regulation in the expression of the cav-1 in both androgen unresponsive cell lines and PCGEM1 gene in DU145 and LNCaP cells. CONCLUSION In summary, we used biochemical and genetics approaches to demonstrate that γ-oryzanol show a promising adjuvant role in the treatment of prostate cancer.
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Affiliation(s)
- Gabriela E Hirsch
- Departamento de Bioquímica, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brasil
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7
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Mougeolle A, Poussard S, Decossas M, Lamaze C, Lambert O, Dargelos E. Oxidative stress induces caveolin 1 degradation and impairs caveolae functions in skeletal muscle cells. PLoS One 2015; 10:e0122654. [PMID: 25799323 PMCID: PMC4370508 DOI: 10.1371/journal.pone.0122654] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Accepted: 02/21/2015] [Indexed: 11/19/2022] Open
Abstract
Increased level of oxidative stress, a major actor of cellular aging, impairs the regenerative capacity of skeletal muscle and leads to the reduction in the number and size of muscle fibers causing sarcopenia. Caveolin 1 is the major component of caveolae, small membrane invaginations involved in signaling and endocytic trafficking. Their role has recently expanded to mechanosensing and to the regulation of oxidative stress-induced pathways. Here, we increased the amount of reactive oxidative species in myoblasts by addition of hydrogen peroxide (H2O2) at non-toxic concentrations. The expression level of caveolin 1 was significantly decreased as early as 10 min after 500 μM H2O2 treatment. This reduction was not observed in the presence of a proteasome inhibitor, suggesting that caveolin 1 was rapidly degraded by the proteasome. In spite of caveolin 1 decrease, caveolae were still able to assemble at the plasma membrane. Their functions however were significantly perturbed by oxidative stress. Endocytosis of a ceramide analog monitored by flow cytometry was significantly diminished after H2O2 treatment, indicating that oxidative stress impaired its selective internalization via caveolae. The contribution of caveolae to the plasma membrane reservoir has been monitored after osmotic cell swelling. H2O2 treatment increased membrane fragility revealing that treated cells were more sensitive to an acute mechanical stress. Altogether, our results indicate that H2O2 decreased caveolin 1 expression and impaired caveolae functions. These data give new insights on age-related deficiencies in skeletal muscle.
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Affiliation(s)
- Alexis Mougeolle
- Univ Bordeaux, Chimie et Biologie des Membranes et Nanoobjets, UMR 5248, F-33600 Pessac, France; CNRS, Chimie et Biologie des Membranes et Nanoobjets, UMR 5248, F-33600 Pessac, France; Bordeaux INP, Chimie et Biologie des Membranes et Nanoobjets, UMR 5248, F-33600 Pessac, France
| | - Sylvie Poussard
- Univ Bordeaux, Chimie et Biologie des Membranes et Nanoobjets, UMR 5248, F-33600 Pessac, France; CNRS, Chimie et Biologie des Membranes et Nanoobjets, UMR 5248, F-33600 Pessac, France; Bordeaux INP, Chimie et Biologie des Membranes et Nanoobjets, UMR 5248, F-33600 Pessac, France
| | - Marion Decossas
- Univ Bordeaux, Chimie et Biologie des Membranes et Nanoobjets, UMR 5248, F-33600 Pessac, France; CNRS, Chimie et Biologie des Membranes et Nanoobjets, UMR 5248, F-33600 Pessac, France; Bordeaux INP, Chimie et Biologie des Membranes et Nanoobjets, UMR 5248, F-33600 Pessac, France
| | - Christophe Lamaze
- Institut Curie—Centre de Recherche, Membrane Dynamics and Mechanics of Intracellular Signaling Team, INSERM U1143, CNRS UMR 3666, Paris, France
| | - Olivier Lambert
- Univ Bordeaux, Chimie et Biologie des Membranes et Nanoobjets, UMR 5248, F-33600 Pessac, France; CNRS, Chimie et Biologie des Membranes et Nanoobjets, UMR 5248, F-33600 Pessac, France; Bordeaux INP, Chimie et Biologie des Membranes et Nanoobjets, UMR 5248, F-33600 Pessac, France
| | - Elise Dargelos
- Univ Bordeaux, Chimie et Biologie des Membranes et Nanoobjets, UMR 5248, F-33600 Pessac, France; CNRS, Chimie et Biologie des Membranes et Nanoobjets, UMR 5248, F-33600 Pessac, France; Bordeaux INP, Chimie et Biologie des Membranes et Nanoobjets, UMR 5248, F-33600 Pessac, France
- * E-mail:
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8
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Shiroto T, Romero N, Sugiyama T, Sartoretto JL, Kalwa H, Yan Z, Shimokawa H, Michel T. Caveolin-1 is a critical determinant of autophagy, metabolic switching, and oxidative stress in vascular endothelium. PLoS One 2014; 9:e87871. [PMID: 24498385 PMCID: PMC3912129 DOI: 10.1371/journal.pone.0087871] [Citation(s) in RCA: 93] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2013] [Accepted: 12/30/2013] [Indexed: 01/29/2023] Open
Abstract
Caveolin-1 is a scaffolding/regulatory protein that interacts with diverse signaling molecules. Caveolin-1null mice have marked metabolic abnormalities, yet the underlying molecular mechanisms are incompletely understood. We found the redox stress plasma biomarker plasma 8-isoprostane was elevated in caveolin-1null mice, and discovered that siRNA-mediated caveolin-1 knockdown in endothelial cells promoted significant increases in intracellular H2O2. Mitochondrial ROS production was increased in endothelial cells after caveolin-1 knockdown; 2-deoxy-D-glucose attenuated this increase, implicating caveolin-1 in control of glycolytic pathways. We performed unbiased metabolomic characterizations of endothelial cell lysates following caveolin-1 knockdown, and discovered strikingly increased levels (up to 30-fold) of cellular dipeptides, consistent with autophagy activation. Metabolomic analyses revealed that caveolin-1 knockdown led to a decrease in glycolytic intermediates, accompanied by an increase in fatty acids, suggesting a metabolic switch. Taken together, these results establish that caveolin-1 plays a central role in regulation of oxidative stress, metabolic switching, and autophagy in the endothelium, and may represent a critical target in cardiovascular diseases.
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Affiliation(s)
- Takashi Shiroto
- Cardiovascular Division, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Natalia Romero
- Cardiovascular Division, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Toru Sugiyama
- Cardiovascular Division, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Juliano L. Sartoretto
- Cardiovascular Division, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Hermann Kalwa
- Cardiovascular Division, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Zhonghua Yan
- Cardiovascular Division, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Hiroaki Shimokawa
- Department of Cardiovascular Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Thomas Michel
- Cardiovascular Division, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
- * E-mail:
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9
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Bitar MS, Abdel-Halim SM, Al-Mulla F. Caveolin-1/PTRF upregulation constitutes a mechanism for mediating p53-induced cellular senescence: implications for evidence-based therapy of delayed wound healing in diabetes. Am J Physiol Endocrinol Metab 2013; 305:E951-63. [PMID: 23941874 DOI: 10.1152/ajpendo.00189.2013] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
A heightened state of oxidative stress and senescence of fibroblasts constitute potential therapeutic targets in nonhealing diabetic wounds. Here, we studied the underlying mechanism mediating diabetes-induced cellular senescence using in vitro cultured dermal fibroblasts and in vivo circular wounds. Our results demonstrated that the total antioxidant capacity and mRNA levels of thioredoxinreductase and glucose-6-phosphate dehydrogenase as well as the ratio of NADPH/NADP were decreased markedly in fibroblasts from patients with type 2 diabetes (DFs). Consistent with this shift in favor of excessive reactive oxygen species, DFs also displayed a significant increase in senescence-associated β-galactosidase activity and phospho-γ-histone H2AX (pH2AX) level. Moreover, the ability of PDGF to promote cell proliferation/migration and regulate the phosphorylation-dependent activation of Akt and ERK1/2 appears to be attenuated as a function of diabetes. Mechanistically, we found that diabetes-induced oxidative stress upregulated caveolin-1 (Cav-1) and PTRF expression, which in turn sequestered Mdm2 away from p53. This process resulted in the activation of a p53/p21-dependent pathway and the induction of premature senescence in DFs. Most of the aforementioned oxidative stress and senescence-based features observed in DFs were recapitulated in a 10-day-old diabetic wound. Intriguingly, we confirmed that the targeted depletion of Cav-1 or PTRF using siRNA- or Vivo-Morpholino antisense-based gene therapy markedly inhibited diabetes/oxidative stress-induced premature senescence and also accelerated tissue repair in this disease state. Overall, our data illuminate Cav-1/PTRF-1 as a key player of a novel signaling pathway that may link a heightened state of oxidative stress to cellular senescence and impaired wound healing in diabetes.
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Affiliation(s)
- Milad S Bitar
- Department of Pharmacology and Toxicology, Kuwait University, Safat, Kuwait
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10
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Schudel BR, Harmon B, Abhyankar VV, Pruitt BW, Negrete OA, Singh AK. Microfluidic platforms for RNA interference screening of virus-host interactions. Lab Chip 2013; 13:811-817. [PMID: 23361404 DOI: 10.1039/c2lc41165b] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
RNA interference (RNAi) is a powerful tool for functional genomics with the capacity to comprehensively analyze host-pathogen interactions. High-throughput RNAi screening is used to systematically perturb cellular pathways and discover therapeutic targets, but the method can be tedious and requires extensive capital equipment and expensive reagents. To aid in the development of an inexpensive miniaturized RNAi screening platform, we have developed a two part microfluidic system for patterning and screening gene targets on-chip to examine cellular pathways involved in virus entry and infection. First, a multilayer polydimethylsiloxane (PDMS)-based spotting device was used to array siRNA molecules into 96 microwells targeting markers of endocytosis, along with siRNA controls. By using a PDMS-based spotting device, we remove the need for a microarray printer necessary to perform previously described small scale (e.g. cellular microarrays) and microchip-based RNAi screening, while still minimizing reagent usage tenfold compared to conventional screening. Second, the siRNA spotted array was transferred to a reversibly sealed PDMS-based screening platform containing microchannels designed to enable efficient cell loading and transfection of mammalian cells while preventing cross-contamination between experimental conditions. Validation of the screening platform was examined using Vesicular stomatitis virus and emerging pathogen Rift Valley fever virus, which demonstrated virus entry pathways of clathrin-mediated endocytosis and caveolae-mediated endocytosis, respectively. The techniques here are adaptable to other well-characterized infection pathways with a potential for large scale screening in high containment biosafety laboratories.
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Affiliation(s)
- Benjamin R Schudel
- Sandia National Laboratories, Department of Biotechnology and Bioengineering, Livermore, CA 94551, USA
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11
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Sharma S, Singh M, Sharma PL. Ameliorative effect of daidzein: a caveolin-1 inhibitor in vascular endothelium dysfunction induced by ovariectomy. Indian J Exp Biol 2012; 50:28-34. [PMID: 22279937] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Estrogen deficiency was produced in female Sprague-Dawley rats by surgical removal of both the ovaries and these animals were used 4 weeks later. Endothelium-dependent and endothelium-independent relaxations due to acetylcholine and sodium nitroprusside were observed respectively, in isolated rat thoracic aortic ring preparation. Extent of lipid peroxidation was measured by estimating serum TBARS. Integrity of vascular endothelium was assessed using hematoxylin and eosin staining. Generation of nitric oxide was measured indirectly, by estimating serum and urinary nitrite/nitrate concentration. Ovariectomy produced significant vascular endothelial dysfunction, measured in terms of reduced acetylcholine-induced endothelium-dependent vasorelaxation, serum and urinary nitrite/nitrate concentration and impairment of integrity of vascular endothelium. Administration of daidzein (0.2 mgkg(-1)day(-1), sc 0.4 mgkg(-1)day(-1), sc and 0.8 mgkg(-1)day(-1), sc) and Atorvastatin (30 mgkg(-1)day(-1), po Positive Control) for one week markedly improved vascular endothelial dysfunction due to increase in nitric oxide bioavailability perhaps by inhibiting caveolin-1 and activation of PI3K-AKT pathway.
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Affiliation(s)
- Saurabh Sharma
- Cardiovascular Division, Department of Pharmacology, ISF College of Pharmacy, Moga 142 001, India
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12
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Adebola TJ, Usha R. Inhibitors caveolin-1 and protein kinase G show differential subcellular colocalization with Nitric oxide synthase. Afr Health Sci 2011; 11:526-534. [PMID: 22649431 PMCID: PMC3362974] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2023] Open
Abstract
BACKGROUND Nitric oxide synthase (NOS) is negatively regulated by protein-protein interactions with caveolin-1 before extracellular activating signals release it for nitric oxide (NO) production. Smooth muscle protein kinase G (PKG) is a down-stream effector of NO signaling for relaxation of vascular smooth muscle cells (SMC). The PKG is also found in endothelial cells and it inhibits activated NOS within endothelial cells. METHODS We used confocal fluorescence microscopy to colocalize the inhibitors caveolin-1 and PKG with NOS in freshly isolated neonatal lamb endothelial cells in order to corroborate the speculation of their differential effects on NOS. The roles of caveolin-1 and PKG as regulators of NOS were investigated by examining their respective subcellular sites of colocalization with NOS using qualitative fluorescence immunohistochemistry and confocal microscopy. RESULTS Caveolin-1 was colocalized with NOS in the plasma membrane and Golgi. The PKG1-beta isoform was colocalized with serine116 phosphorylated NOS in the cytosol and in vesicular structures seen in the endoplasmic reticulum and in the nuclear region. CONCLUSION We conclude that unlike caveolin-1, a known pre-activation inhibitor of nascent NOS, PKG may be a post-activation inhibitor of NOS, possibly important for the recycling of the spent enzyme.
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Affiliation(s)
- T J Adebola
- Department of Pharmacology, Lagos State University College of Medicine. 1 Oba Akinjobi Way, GRA, Ikeja, Lagos, P.M.B. 21266, Ikeja, Lagos, Nigeria.
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13
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Horiguchi K, Fujiwara K, Ilmiawati C, Kikuchi M, Tsukada T, Kouki T, Yashiro T. Caveolin 3-mediated integrin β1 signaling is required for the proliferation of folliculostellate cells in rat anterior pituitary gland under the influence of extracellular matrix. J Endocrinol 2011; 210:29-36. [PMID: 21508095 DOI: 10.1530/joe-11-0103] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Folliculostellate (FS) cells in the anterior pituitary gland are believed to have multifunctional properties. Using transgenic rats that express green fluorescent protein (GFP) specifically in FS cells in the anterior pituitary gland (S100b-GFP rats), we recently revealed that FS cells in primary culture exhibited marked proliferation in the presence of laminin, an extracellular matrix (ECM) component of the basement membrane. In a process referred to as matricrine action, FS cells receive ECM as a signal through their receptors, which results in morphological and functional changes. In this study, we investigated matricrine signaling in FS cells and observed that the proliferation of FS cells is mediated by integrin β1, which is involved in various signaling pathways for cell migration and proliferation in response to ECM. Then, we analyzed downstream events of the integrin β1 signaling pathway in the proliferation of FS cells and identified caveolin 3 as a potential candidate molecule. Caveolin 3 is a membrane protein that binds cholesterol and a number of signaling molecules that interact with integrin β1. Using specific small interfering RNA of caveolin 3, the proliferation of FS cells was inhibited. Furthermore, caveolin 3 drove activation of the mitogen-activated protein kinase (MAPK) signaling cascades, which resulted in upregulation of cyclin D1 in FS cells. These findings suggest that matricrine signaling in the proliferation of FS cells was transduced by a caveolin 3-mediated integrin β1 signaling pathway and subsequent activation of the MAPK pathway.
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Affiliation(s)
- Kotaro Horiguchi
- Division of Histology and Cell Biology, Department of Anatomy, Jichi Medical University School of Medicine, 3311-1 Yakushiji, Shimotsuke, Tochigi 329-0498, Japan.
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14
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Zhao X, Ma C, Cai X, Lei D, Liu D, Xu F, Jin T, Liu J, Pan X. RNA interference of caveolin-1 via lentiviral vector inhibits growth of hypopharyngeal squamous cell carcinoma FaDu cells In Vitro and In Vivo. Asian Pac J Cancer Prev 2011; 12:397-401. [PMID: 21545202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2023] Open
Abstract
OBJECTIVE To investigate the effects of caveolin-1 (CAV1) on the growth of hypopharyngeal squamous cell carcinoma (HSCC) FaDu cells in vitro and in vivo. METHODS A CAV1-RNAi-lentivirus construct was transfected into FaDu cells and expression of caveolin-1 was tested by RT-PCR and western blotting analysis. Cell apoptosis was analyzed by transferase-medisated dUTP nick-end labeling (TUNEL) assay. Tumor inhibition effects were investigated by injecting rCAV1-RNAi-lentivirus construct into tumors created with FaDu cells in the HSCC mouse model, with the empty-vector lentivirus as a control. CAV1 expression in xenografts was tested by RT-PCR and immunohistochemistry. RESULTS RT-PCR and western blot analysis demonstrated successful construction of the CAV1-RNAi-lentivirus construct producing small hairpin RNA. The average weights and volumes of tumor in mice treated with CAV1-RNAi-lentivirus were lower than in mice with control treatment (P < 0.05). RT-PCR revealed weak positive expression of CAV1 in CAV1-construct-treated xenografts and immunohistochemistry confirmed lower CAV1 expression than in controls.(P < 0.05). In addition, downregulation of CAV1 increased cell apoptosis in vitro. CONCLUSION The growth of HSCCs could be inhibited by recombinant CAV1-RNAi-lentivirus in vitro and in vivo.
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Affiliation(s)
- Xuening Zhao
- Department of Otolaryngology, Qilu Hospital, Shandong University, Jinan, PR China
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15
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Brainard AM, Korovkina VP, England SK. Disruption of the maxi-K-caveolin-1 interaction alters current expression in human myometrial cells. Reprod Biol Endocrinol 2009; 7:131. [PMID: 19930645 PMCID: PMC2785819 DOI: 10.1186/1477-7827-7-131] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/05/2009] [Accepted: 11/23/2009] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND One determinant of the total K+ myometrial smooth muscle cell (MSMC) current is the large conductance, calcium- and voltage-activated potassium channel (maxi-K channel). This channel provides a repolarizing current in response to excitatory stimuli, most notably in response to increases in the levels of intracellular Ca2+, and blocking the channel by pharmacological means induces the depolarization of MSMCs and also enhances contraction strength. In MSMCs, maxi-K channels can reside in the caveolae, where they associate with the scaffolding protein caveolin-1 (cav-1). The aim of this study was to investigate the consequences of this interaction - more specifically, how disruption of the association between the maxi-K channel and cav-1 may influence the current expression and excitability of myometrial cells - with the aim of better understanding the mechanisms that underlie the regulation of normal and aberrant uterine function. METHODS Myometrial biopsies were collected from women undergoing elective C-sections. From these samples, myometrial cells were isolated, cultured, infected with a virus containing either caveolin-1 (cav-1) siRNA or scrambled cav-1 siRNA, and finally subjected to patch-clamp analysis. Mutant caveolin-binding site maxi-K channel constructs were generated and transfected into mouse Ltk- fibroblasts. Channel activity, expression, association, and localization were examined by patch-clamping, Western blot, immunoprecipitation, and immunofluorescence, respectively. RESULTS The caveolin-1 siRNA suppressed the total K+ current in human myometrial smooth muscle cells (hMSMC), as evident from comparison to the currents generated by both non-infected cells and cells infected with scrambled siRNA controls. The interaction between the maxi-K channel and caveolin depends on a region in the channel's C-terminal caveolin-binding site. Mutations of aromatic residues in this site (mutant F1012A, mutant Y1007A, F1012A and mutant Y1007A, F1012A, Y1015A) resulted in a decrease in K+ current compared to that produced by wild-type channels transfected into mouse Ltk- fibroblasts. However, mutation of all three aromatic amino acids (mutant Y1007A, F1012A, Y1015A) was necessary to disrupt the association between caveolin and the maxi-K channel, as visualized by immunofluorescence and immunoprecipitation. CONCLUSION Our results suggest that disruption of the caveolin-binding site interferes with the cav-1/maxi-K channel interaction, and that lack of the cav-1/maxi-K channel interaction in MSMCs attenuates the total K+ channel current of the cell.
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Affiliation(s)
- Adam M Brainard
- Department of Molecular Physiology and Biophysics, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Victoria P Korovkina
- Department of Obstetrics and Gynecology, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Sarah K England
- Department of Molecular Physiology and Biophysics, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
- Department of Obstetrics and Gynecology, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
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16
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Du ZM, Hu CF, Shao Q, Huang MY, Kou CW, Zhu XF, Zeng YX, Shao JY. Upregulation of caveolin-1 and CD147 expression in nasopharyngeal carcinoma enhanced tumor cell migration and correlated with poor prognosis of the patients. Int J Cancer 2009; 125:1832-41. [PMID: 19582878 DOI: 10.1002/ijc.24531] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Expression of caveolin-1 (Cav-1) and extracellular matrix metalloproteinase inducer (EMMPRIN/CD147) and their prognostic significance were analyzed in archive NPC samples. Cav-1 and CD147 were overexpressed in 49.48% (96/194) and 59.39% (117/197) of NPC, respectively. Both Cav-1 and CD147 expression levels correlated significantly with metastasis (p = 0.025 and 0.017, respectively) and a lower 5-year survival rate (p = 0.02 and 0.0009, respectively). In addition, Cav-1 expression levels correlated significantly with local recurrence (p = 0.038). Multivariate Cox regression analysis indicated that combination of high Cav-1 and CD147 expression was a significant, independent prognosis predictor in patients with NPC (HR = 2.135; p = 0.006). Functional studies revealed that overexpression of Cav-1 promoted secretion of MMP-3 and MMP-11 (active) proteins, as well as an increase in the migratory ability of CNE1 and CNE2 cells, while siRNA-mediated silencing of Cav-1 or CD147 led to reduced levels of MMP-3 and MMP-11(active) secretion, and reduced migration capacity of CNE1 and CNE2 cells. We observed a positive correlation between Cav-1 and CD147 expression in NPC (rho = 0.330, p = 0.000), CD147 protein levels were upregulated in Cav-1 overexpressing CNE1 and CNE2 cells, whereas siRNA-mediated silencing of Cav-1 led to the downregulation of CD147 expression. Our results indicate that Cav-1 and CD147 overexpression predict poor NPC prognosis and enhanced tumor cell migration, which is associated with MMP-3 and MMP-11 (active) secretion.
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Affiliation(s)
- Zi-Ming Du
- State Key Laboratory of Oncology in Southern China, Sun Yat-Sen University Cancer Center, Guangzhou 510060, People's Republic of China
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17
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Vela EM, Zhang L, Colpitts TM, Davey RA, Aronson JF. Arenavirus entry occurs through a cholesterol-dependent, non-caveolar, clathrin-mediated endocytic mechanism. Virology 2007; 369:1-11. [PMID: 17698159 PMCID: PMC2227908 DOI: 10.1016/j.virol.2007.07.014] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2006] [Revised: 06/08/2007] [Accepted: 07/10/2007] [Indexed: 12/20/2022]
Abstract
Arenaviruses are important causes of viral hemorrhagic fevers in humans. Arenavirus infection of cells occurs via a pH-dependent endocytic route, but detailed studies of entry pathways have not been done. We investigated the role of cell membrane cholesterol, caveolae, and clathrin coated pits in infection by Lassa virus (LASV), which utilizes alpha-dystroglycan (alpha-DG) as a receptor, and Pichindé virus (PICV), which does not. Depletion of cellular cholesterol by treatment with methyl betacyclodextrin (MbetaCD) or nystatin/progesterone inhibited PICV replication and transfer of packaged marker gene by LASV or PICV pseudotyped retroviral particles. In cells lacking caveolae due to silencing of the caveolin-1 gene, no inhibition of PICV infection or LASV pseudotype transduction was observed. However, PICV infection and LASV and PICV pseudotype transduction was inhibited when an Eps15 dominant negative mutant was used to inhibit clathrin-mediated endocytosis. Altogether, the results indicate that diverse arenaviruses have a common requirement for cell membrane cholesterol and clathrin mediated endocytosis in establishing infection.
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Affiliation(s)
- Eric M Vela
- Department of Pathology, Center for Biodefense and Emerging Infectious Diseases, The University of Texas Medical Branch, 301 University Blvd, Galveston, TX 77555, USA.
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18
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Sawada N, Taketani Y, Amizuka N, Ichikawa M, Ogawa C, Nomoto K, Nashiki K, Sato T, Arai H, Isshiki M, Segawa H, Yamamoto H, Miyamoto KI, Takeda E. Caveolin-1 in extracellular matrix vesicles secreted from osteoblasts. Bone 2007; 41:52-8. [PMID: 17448744 DOI: 10.1016/j.bone.2007.02.030] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2006] [Revised: 02/04/2007] [Accepted: 02/21/2007] [Indexed: 11/29/2022]
Abstract
Caveolin-1 is an essential and signature protein of caveolae, which are small invaginations of the plasma membrane enriched in cholesterol and sphingolipids. Although high levels of expression of caveolin-1 have been demonstrated in osteoblasts as well as endothelial cells, fibroblasts, and muscular cells, the role of caveolin-1 in osteoblasts has not been clarified. Here, we show that caveolin-1 is secreted from osteoblasts in the form of matrix vesicles; extracellular vesicles released from the plasma membrane of osteoblasts. In this study, caveolae and matrix vesicles were similarly enriched in cholesterol and sphingomyelin in fractions isolated from mineralizing MC3T3-E1 cells. Interestingly, in the MC3T3-E1 cells caveolin-1 was enriched in the matrix vesicle fraction as well as the caveolar membrane fraction, and the amount of caveolin-1 in the matrix vesicle fraction increased as differentiation progressed. Localization of caveolin-1 in matrix vesicles was also confirmed in murine tibia. Furthermore, overexpression of caveolin-1 enhanced matrix calcification in MC3T3-E1 cells, whereas knockdown of caveolin-1 diminished it. These results suggest that secreted caveolin-1 as a component of matrix vesicles may play an important role in osteoblast calcification.
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Affiliation(s)
- Naoki Sawada
- Department of Clinical Nutrition, Institute of Health Biosciences, University of Tokushima Graduate School, 3-18-15 Kuramoto-cho, Tokushima 770-8503, Japan
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19
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Moriyama T, Marquez JP, Wakatsuki T, Sorokin A. Caveolar endocytosis is critical for BK virus infection of human renal proximal tubular epithelial cells. J Virol 2007; 81:8552-62. [PMID: 17553887 PMCID: PMC1951339 DOI: 10.1128/jvi.00924-07] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
In recent years, BK virus (BKV) nephritis after renal transplantation has become a severe problem. The exact mechanisms of BKV cell entry and subsequent intracellular trafficking remain unknown. Since human renal proximal tubular epithelial cells (HRPTEC) represent a main natural target of BKV nephritis, analysis of BKV infection of HRPTEC is necessary to obtain additional insights into BKV biology and to develop novel strategies for the treatment of BKV nephritis. We coincubated HRPTEC with BKV and the cholesterol-depleting agents methyl beta cyclodextrin (MBCD) and nystatin (Nys), drugs inhibiting caveolar endocytosis. The percentage of infected cells (detected by immunofluorescence) and the cellular levels of BKV large T antigen expression (detected by Western blot analysis) were significantly decreased in both MBCD- and Nys-treated HPRTEC compared to the level in HRPTEC incubated with BKV alone. HRPTEC infection by BKV was also tested after small interfering RNA (siRNA)-dependent depletion of either the caveolar structural protein caveolin-1 (Cav-1) or clathrin, the major structural protein of clathrin-coated pits. BKV infection was inhibited in HRPTEC transfected with Cav-1 siRNA but not in HRPTEC transfected with clathrin siRNA. The colocalization of labeled BKV particles with either Cav-1 or clathrin was investigated by using fluorescent microscopy and image cross-correlation spectroscopy. The rate of colocalization of BKV with Cav-1 peaked at 4 h after incubation. Colocalization with clathrin was insignificant at all time points. These results suggest that BKV entered into HRPTEC via caveolae, not clathrin-coated pits, and that BKV is maximally associated with caveolae at 4 h after infection, prior to relocation to a different intracellular compartment.
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Affiliation(s)
- Takahito Moriyama
- Division of Nephrology and Kidney Disease Center, Department of Medicine, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA
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Patel HH, Zhang S, Murray F, Suda RYS, Head BP, Yokoyama U, Swaney JS, Niesman IR, Schermuly RT, Pullamsetti SS, Thistlethwaite PA, Miyanohara A, Farquhar MG, Yuan JXJ, Insel PA. Increased smooth muscle cell expression of caveolin-1 and caveolae contribute to the pathophysiology of idiopathic pulmonary arterial hypertension. FASEB J 2007; 21:2970-9. [PMID: 17470567 DOI: 10.1096/fj.07-8424com] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Vasoconstriction and vascular medial hypertrophy, resulting from increased intracellular [Ca2+] in pulmonary artery smooth muscle cells (PASMC), contribute to elevated vascular resistance in patients with idiopathic pulmonary arterial hypertension (IPAH). Caveolae, microdomains within the plasma membrane, contain the protein caveolin, which binds certain signaling molecules. We tested the hypothesis that PASMC from IPAH patients express more caveolin-1 (Cav-1) and caveolae, which contribute to increased capacitative Ca2+ entry (CCE) and DNA synthesis. Immunohistochemistry showed increased expression of Cav-1 in smooth muscle cells but not endothelial cells of pulmonary arteries from patients with IPAH. Subcellular fractionation and electron microscopy confirmed the increase in Cav-1 and caveolae expression in IPAH-PASMC. Treatment of IPAH-PASMC with agents that deplete membrane cholesterol (methyl-beta-cyclodextrin or lovastatin) disrupted caveolae, attenuated CCE, and inhibited DNA synthesis of IPAH-PASMC. Increasing Cav-1 expression of normal PASMC with a Cav-1-encoding adenovirus increased caveolae formation, CCE, and DNA synthesis; treatment of IPAH-PASMC with siRNA targeted to Cav-1 produced the opposite effects. Treatments that down-regulate caveolin/caveolae expression, including cholesterol-lowering drugs, reversed the increased CCE and DNA synthesis in IPAH-PASMC. Increased caveolin and caveolae expression thus contribute to IPAH-PASMC pathophysiology. The close relationship between caveolin/caveolae expression and altered cell physiology in IPAH contrast with previous results obtained in various animal models, including caveolin-knockout mice, thus emphasizing unique features of the human disease. The results imply that disruption of caveolae in PASMC may provide a novel therapeutic approach to attenuate disease manifestations of IPAH.
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Affiliation(s)
- Hemal H Patel
- University of California, San Diego, Department of Pharmacology, 9500 Gilman Dr., La Jolla, CA 92093-0636, USA
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Yang H, He S, Quan Z, Peng W, Yan B, Liu J, Wen F, Cao R, Xu Y, Wen G, Hu W. Small interfering RNA-mediated caveolin-1 knockout on plasminogen activator inhibitor-1 expression in insulin-stimulated human vascular endothelial cells. Acta Biochim Biophys Sin (Shanghai) 2007; 39:224-33. [PMID: 17342262 DOI: 10.1111/j.1745-7270.2007.00270.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
Using human vascular endothelial cells (ECV304) as the target, we studied the effect of caveolin (CAV)-1 in the course of insulin-stimulated expression of plasminogen activator inhibitor (PAI)-1. The appropriate single-stranded oligonucleotides representing the RNAi CAV-1 gene were analyzed by Ambion software. After annealing to generate double-stranded oligonucleotides (ds oligo), it was cloned into the pENTR/U6 entry vector containing RNA polymerase III expression element by T4 DNA ligase. The short hairpin (shRNA) sequences transferred from the pENTR/U6 entry were cloned into the pLenti6/BLOCK-iT-DEST vector with an LR recombination reaction. After identification by sequencing, we successfully constructed the CAV-1 RNAi lentiviral expression system using Gateway technology. Silencing efficiency was assayed by real-time reverse transcription-polymerase chain reaction, immunofluorescence staining and Western blotting. ECV304 cells were cultured in the medium containing different concentrations of insulin (1x10(-9) to 1x10(-7) M) with the CAV-1 gene silenced or not. The expression level and subcellular localization of PAI-1 and CAV-1 were compared using reverse transcription-polymerase chain reaction, immunofluorescence staining and Western blot assay. The results showed that the potent inhibition of CAV-1 expression could reach 85%, and it was specific to the CAV-1-derived shRNA, not the S100A13-derived shRNA. There was no dramatic difference in PAI-1 expression between the RNAi+ and RNAi- ECV304 cells incubated with physiological insulin, but PAI-1 protein did accumulate under the cell membrane. As the concentration of insulin increased, the expression of PAI-1 was up-regulated, whereas the expression of CAV-1 attenuated. Furthermore, PAI-1 clearly augmented after CAV-1 knockdown. These results indicated that hyperinsulinism could promote PAI-1 expression by inhibiting CAV-1, and stabilizing or up-regulating CAV-1 expression in endothelial cells might reduce complications of the great vessels and capillary vessels in diabetes.
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Affiliation(s)
- Huiling Yang
- Institute of Clinic Medicine, the First Affiliated Hospital of Nanhua University, Hengyang, China
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22
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Tirado OM, Mateo-Lozano S, Villar J, Dettin LE, Llort A, Gallego S, Ban J, Kovar H, Notario V. Caveolin-1 (CAV1) is a target of EWS/FLI-1 and a key determinant of the oncogenic phenotype and tumorigenicity of Ewing's sarcoma cells. Cancer Res 2006; 66:9937-47. [PMID: 17047056 DOI: 10.1158/0008-5472.can-06-0927] [Citation(s) in RCA: 115] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Tumors of the Ewing's sarcoma family (ESFT), such as Ewing's sarcoma (EWS) and primitive neuroectodermal tumors (PNET), are highly aggressive malignancies predominantly affecting children and young adults. ESFT express chimeric transcription factors encoded by hybrid genes fusing the EWS gene with several ETS genes, most commonly FLI-1. EWS/FLI-1 proteins are responsible for the malignant phenotype of ESFT, but only few of their transcriptional targets are known. Using antisense and short hairpin RNA-mediated gene expression knockdown, array analyses, chromatin immunoprecipitation methods, and reexpression studies, we show that caveolin-1 (CAV1) is a new direct target of EWS/FLI-1 that is overexpressed in ESFT cell lines and tumor specimens and is necessary for ESFT tumorigenesis. CAV1 knockdown led to up-regulation of Snail and the concomitant loss of E-cadherin expression. Consistently, loss of CAV1 expression inhibited the anchorage-independent growth of EWS cells and markedly reduced the growth of EWS cell-derived tumors in nude mice xenografts, indicating that CAV1 promotes the malignant phenotype in EWS carcinogenesis. Reexpression of CAV1 or E-cadherin in CAV1 knockdown EWS cells rescued the oncogenic phenotype of the original EWS cells, showing that the CAV1/Snail/E-cadherin pathway plays a central role in the expression of the oncogenic transformation functions of EWS/FLI-1. Overall, these data identify CAV1 as a key determinant of the tumorigenicity of ESFT and imply that targeting CAV1 may allow the development of new molecular therapeutic strategies for ESFT patients.
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MESH Headings
- Animals
- Cadherins/biosynthesis
- Cadherins/genetics
- Caveolin 1/antagonists & inhibitors
- Caveolin 1/genetics
- Caveolin 1/metabolism
- Caveolin 1/physiology
- Cell Adhesion/genetics
- Cell Growth Processes/genetics
- Cell Line, Tumor
- Chromatin Immunoprecipitation
- Down-Regulation
- Gene Expression Regulation, Neoplastic
- HT29 Cells
- Humans
- Mice
- Mice, Inbred BALB C
- Mice, Nude
- Oncogene Proteins, Fusion/genetics
- Oncogene Proteins, Fusion/metabolism
- Oncogene Proteins, Fusion/physiology
- Proto-Oncogene Protein c-fli-1/genetics
- Proto-Oncogene Protein c-fli-1/metabolism
- Proto-Oncogene Protein c-fli-1/physiology
- RNA, Antisense/genetics
- RNA-Binding Protein EWS
- Sarcoma, Ewing/genetics
- Sarcoma, Ewing/metabolism
- Sarcoma, Ewing/pathology
- Snail Family Transcription Factors
- Transcription Factors/biosynthesis
- Transcription Factors/genetics
- Up-Regulation
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Affiliation(s)
- Oscar M Tirado
- Laboratory of Experimental Carcinogenesis, Department of Radiation Medicine, Georgetown University Medical Center, Washington, DC 20057, USA
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23
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Hunter I, Nixon GF. Spatial compartmentalization of tumor necrosis factor (TNF) receptor 1-dependent signaling pathways in human airway smooth muscle cells. Lipid rafts are essential for TNF-alpha-mediated activation of RhoA but dispensable for the activation of the NF-kappaB and MAPK pathways. J Biol Chem 2006; 281:34705-15. [PMID: 16982613 PMCID: PMC2653078 DOI: 10.1074/jbc.m605738200] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Tumor necrosis factor (TNF)-alpha-induced activation of RhoA, mediated by TNF receptor 1 (TNFR1), is a prerequisite step in a pathway that leads to increased 20-kDa light chain of myosin (MLC20) phosphorylation and airway smooth muscle contraction. In this study, we have investigated the proximal events in TNF-alpha-induced RhoA activation. TNFR1 is localized to both lipid raft and nonraft regions of the plasma membrane in primary human airway smooth muscle cells. TNF-alpha engagement of TNFR1 recruited the adaptor proteins TRADD, TRAF-2, and RIP into lipid rafts and activated RhoA, NF-kappaB, and MAPK pathways. Depletion of cholesterol from rafts with methyl-beta-cyclodextrin caused a redistribution of TNFR1 to nonraft plasma membrane and prevented ligand-induced RhoA activation. By contrast, TNF-alpha-induced activation of NF-kappaB and MAPKs was unaffected by methyl-beta-cyclodextrin indicating that, in airway smooth muscle cells, activation of these pathways occurred independently of lipid rafts. Targeted knockdown of caveolin-1 completely abrogated TNF-alpha-induced RhoA activation, identifying this raft-resident protein as a positive regulator of the activation process. The signaling adaptors TRADD and RIP were also found to be necessary for ligand-induced RhoA activation. Taken together, our results suggest that in airway smooth muscle cells, spatial compartmentalization of TNFR1 provides a mechanism for generating distinct signaling outcomes in response to ligand engagement and define a mechanistic role for lipid rafts and caveolin-1 in TNF-alpha-induced activation of RhoA.
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Affiliation(s)
- Irene Hunter
- School of Medical Sciences, University of Aberdeen, IMS Building, Foresterhill, Aberdeen AB25 2ZD, United Kingdom.
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24
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Siddiqui SS, Siddiqui ZK, Uddin S, Minshall RD, Malik AB. p38 MAPK activation coupled to endocytosis is a determinant of endothelial monolayer integrity. Am J Physiol Lung Cell Mol Physiol 2006; 292:L114-24. [PMID: 16891390 DOI: 10.1152/ajplung.00257.2005] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
We show in rat lung microvessel endothelial cells (RLMVEC) that endocytosis is a critical determinant of activation of mitogen-activated protein kinase (MAPK) and thereby regulates endothelial monolayer integrity. In RLMVEC grown in serum-free medium, we observed that albumin supplementation induced the phosphorylation of p38 MAPK within 30 min, which persisted for up to 2 h. Engagement of the endocytic machinery regulated the activation of p38 MAPK that contributed to endothelial cell proliferation and reduction of apoptosis. We also observed an interaction between the caveolar protein caveolin-1 and p38 MAPK with reciprocal coimmunoprecipitation assays and colocalization using double-label immunofluorescence staining. Knockdown of caveolin-1 expression with small interfering RNA significantly reduced endocytosis and activation of p38 MAPK and interfered with the ability of endothelial cells to form a confluent monolayer. Thus caveolae-mediated endocytosis and concomitant activation of p38 MAPK may help to maintain endothelial monolayer integrity by signaling proliferation and survival of endothelial cells.
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Affiliation(s)
- Shahid S Siddiqui
- Department of Pharmacology, University of Illinois College of Medicine, 835 South Wolcott Ave. (M/C 868), Chicago, IL 60612, USA.
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25
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Zhang Q, Furukawa K, Chen HH, Fujinawa R, Kozutsumi Y, Suzuki A, Urano T, Furukawa K. Down-regulation of caveolin-1 in mouse Lewis lung cancer P29 is a causal factor for the malignant properties in a high-metastatic subline. Oncol Rep 2006; 16:289-94. [PMID: 16820905] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/10/2023] Open
Abstract
In order to analyze molecular mechanisms for cancer metastasis, we established a high-metastatic subline H7-Lu from a subline H7 of mouse Lewis lung cancer (P29) by repeated injection into tail veins. H7-Lu exhibited increased proliferation and invasion activity. Analysis of gene expression profiles between the parent H7 and H7-Lu revealed that several genes were down-regulated in H7-Lu. One of them, caveolin-1, was a component of lipid/rafts. After confirming the down-regulation of caveolin-1 mRNA by real-time RT-PCR and reduction of the protein by immunoblotting, respectively, H7 was transfected with siRNA for caveolin-1 to examine the role of caveolin-1 in H7-Lu. mRNA of the caveolin-1 gene was suppressed to approximately one third of the original level in H7 cells transfected with siRNA. The transfectant cells showed significantly increased cell proliferation and motility when analyzed by MTT assay and scratching wound healing assay, respectively. In the siRNA-transfectant cells, both ERK1/2 and Akt showed stronger phosphorylation than the mock-transfectant cells indicating that both of these signaling pathways were activated in caveolin-1-suppressed cells. These situations seem to reflect some aspects of the cellular changes in the high metastatic subline H7-Lu. Thus, down-regulation of caveolin-1 in a high-metastatic subline of Lewis lung cancer as defined by DNA array is really a causal factor for the increased malignant properties.
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Affiliation(s)
- Qing Zhang
- Department of Biochemistry II, Nagoya University Graduate School of Medicine, Nagoya 466-0065, Japan
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26
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Sasai K, Kakumoto K, Hanafusa H, Akagi T. The Ras-MAPK pathway downregulates Caveolin-1 in rodent fibroblast but not in human fibroblasts: implications in the resistance to oncogene-mediated transformation. Oncogene 2006; 26:449-55. [PMID: 16832346 DOI: 10.1038/sj.onc.1209792] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Normal human diploid fibroblasts (HDFs) are refractory to oncogene-mediated transformations in vitro, compared with rodent fibroblasts. As successful oncogene-mediated transformations of normal HDFs have been reported using the human telomerase catalytic subunit, it has been considered that telomerase activity contributes to the species-specific transformability. However, these transformed HDFs are much less malignant compared with those of rodent cells, suggesting the existence of undefined mechanisms that render HDFs resistant to malignant transformation. Here, cDNA microarray analysis identified caveolin-1 as one of the possible cellular factors involved in such mechanisms. The mitogen-activated protein kinases (MAPK) pathway downregulates Caveolin-1 in rodent fibroblasts, transformed by coexpression of the SV40 early region and activated H-Ras. In contrast, the coexpression of these two oncogenes in HDFs failed to reduce the expression level of Caveolin-1. These results strongly suggest the presence of critical differences in events following the phosphorylation of ERK during the activation process of the MAPK signaling pathway between human and rodent cells, as the ERK protein was similarly phosphorylated in both systems. Furthermore, the small interfering RNA-mediated suppression of Caveolin-1 facilitated the oncogene-mediated transformation of normal HDFs, clearly indicating that the differences in the transformability between human and rodent cells are due, at least in part, to the mechanism responsible for the resistance to Ras-induced Caveolin-1 downregulation in HDFs.
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Affiliation(s)
- K Sasai
- Laboratory of Molecular Oncology, Osaka Biosciencce Institute, Ibaraki, Osaka, Japan
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27
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Iguchi K, Matsunaga S, Nakano T, Usui S, Hirano K. Inhibition of caveolin-1 expression by incadronate in PC-3 prostate cells. Anticancer Res 2006; 26:2977-81. [PMID: 16886623] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
BACKGROUND Caveolin-1 is an essential component of caveolae and its expression is known to be increased in human prostate cancer. The reduction of caveolin-1 expression has been reported to decrease the tumorigenic and metastatic potential of prostate cancer. MATERIALS AND METHODS Caveolin-1 expression was determined by real-time RT-PCR and Western blot analysis. RESULTS Incadronate, a third-generation bisphosphonate, was found to inhibit the caveolin-1 mRNA and protein expression in PC-3 prostate cells. The decrease in caveolin-1 mRNA expression by incadronate was prevented by co-incubation with geranylgeranyol, but not with farnesol. Moreover, treatment of GGTI-286, a geranylgeranyl transferase inhibitor, but not FTI-277, a farnesyl transferase inhibitor, also resulted in the inhibition of caveolin-1 mRNA expression. CONCLUSION These results indicate that the decrease in caveolin-1 expression elicited by incadronate is related to the inhibition of protein geranylgeranylation.
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Affiliation(s)
- Kazuhiro Iguchi
- Laboratory of Pharmaceutics, Gifu Pharmaceutical University, Gifu, Gifu 502-8585, Japan.
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28
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Abstract
Caveolae are specialized flask-shaped lipid rafts enriched in cholesterol, sphingolipids, and structural marker proteins termed caveolins. Caveolins are highly conserved hairpin loop-shaped, oligomeric proteins of 22-24 kDa. Besides the plasma cell membrane, caveolins are also present in mitochondria, the endoplasmatic reticulum, the Golgi/trans-Golgi network, and secretory vesicles. They play a critical role in normal vesicular transport, cholesterol homeostasis, and signal transduction. Conversely, dysregulation of caveolin-1 has been associated with several human diseases including multiple myeloma, an incurable malignancy characterized by excess monoclonal plasma cells within the bone marrow. In this mini-review, we characterize the functional role of caveolin-1 in multiple myeloma, and present the preclinical rationale for novel potential therapeutic approaches targeting caveolin-1 in multiple myeloma.
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Affiliation(s)
- Klaus Podar
- Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Jerome Lipper Multiple Myeloma Center, 44 Binney Street, Boston, MA 02115, USA.
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29
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Predescu SA, Predescu DN, Shimizu K, Klein IK, Malik AB. Cholesterol-dependent syntaxin-4 and SNAP-23 clustering regulates caveolar fusion with the endothelial plasma membrane. J Biol Chem 2005; 280:37130-8. [PMID: 16118213 DOI: 10.1074/jbc.m505659200] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
We determined the organization of target (t) SNARE proteins on the basolateral endothelial plasma membrane (PM) and their role in the mechanism of caveolar fusion. Studies were performed in a cell-free system involving endothelial PM sheets and isolated biotin-labeled caveolae. We monitored the fusion of caveolae with the PM by the detection of biotin-streptavidin complexes using correlative high resolution fluorescence microscopy and gold labeling electron microscopy on ultrathin sections of PM sheets. Imaging of PM sheets demonstrated and biochemical findings showed that the t-SNARE proteins present in endothelial cells (SNAP-23 and syntaxin-4) formed cholesterol-dependent clusters in discrete areas of the PM. Upon fusion of caveolae with the target PM, 50% of the caveolae co-localized with the t-SNARE clusters, indicating that these caveolae were at the peak of the fusion reaction. Fluorescent streptavidin staining of PM sheets correlated with the ultrastructure in the same area. These findings demonstrate that t-SNARE clusters in the endothelial target PM serve as the fusion sites for caveolae during exocytosis.
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Affiliation(s)
- Sanda A Predescu
- Department of Pharmacology and the Center for Lung and Vascular Biology, University of Illinois College of Medicine, Chicago, Illinois 60612, USA
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