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Turner DGP, Tyan L, DeGuire FC, Medvedev RY, Stroebel SJ, Lang D, Glukhov AV. Caveolin-3 prevents swelling-induced membrane damage via regulation of I Cl,swell activity. Biophys J 2022; 121:1643-1659. [PMID: 35378081 PMCID: PMC9117929 DOI: 10.1016/j.bpj.2022.04.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 02/09/2022] [Accepted: 03/31/2022] [Indexed: 11/21/2022] Open
Abstract
Caveola membrane structures harbor mechanosensitive chloride channels (MCCs; including chloride channel 2, chloride channel 3, and SWELL1, also known as LRRC8A) that form a swelling-activated chloride current (ICl,swell) and play an important role in cell volume regulation and mechanoelectrical signal transduction. However, the role of the muscle-specific caveolar scaffolding protein caveolin-3 (Cav3) in regulation of MCC expression, activity, and contribution to membrane integrity in response to mechanical stress remains unclear. Here we showed that Cav3-transfected (Cav3-positive) HEK293 cells were significantly resistant to extreme (<20 milliosmole) hypotonic swelling compared with native (Cav3-negative) HEK293 cells; the percentage of cells with membrane damage decreased from 45% in Cav3-negative cells to 17% in Cav3-positive cells (p < 0.05). This mechanoprotection was significantly reduced (p < 0.05) when cells were exposed to the ICl,swell-selective inhibitor 4-[(2-butyl-6,7-dichloro-2-cyclopentyl-2,3-dihydro-1-oxo-1H-inden-5-yl)oxy]butanoic acid (10 μM). These results were recapitulated in isolated mouse ventricular myocytes, where the percentage of cardiomyocytes with membrane damage increased from 47% in control cells to 78% in 4-[(2-butyl-6,7-dichloro-2-cyclopentyl-2,3-dihydro-1-oxo-1H-inden-5-yl)oxy]butanoic acid-treated cells (p < 0.05). A higher resistance to hypotonic swelling in Cav3-positive HEK293 cells was accompanied by a significant twofold increase of ICl,swell current density and SWELL1 protein expression, whereas ClC-2/3 protein levels remained unchanged. Förster resonance energy transfer analysis showed a less than 10-nm membrane and intracellular association between Cav3 and SWELL1. Cav3/SWELL1 membrane Förster resonance energy transfer efficiency was halved in mild (220 milliosmole) hypotonic solution as well as after disruption of caveola structures via cholesterol depletion by 1-h treatment with 10 mM methyl-β-cyclodextrin. A close association between Cav3 and SWELL1 was confirmed by co-immunoprecipitation analysis. Our findings indicate that, in the MCCs tested, SWELL1 abundance and activity are regulated by Cav3 and that their association relies on membrane tension and caveola integrity. This study highlights the mechanoprotective role of Cav3, which is facilitated by complimentary SWELL1 expression and activity.
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Affiliation(s)
- Daniel G P Turner
- Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin
| | - Leonid Tyan
- Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin
| | - Frank C DeGuire
- Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin
| | - Roman Y Medvedev
- Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin
| | - Sami J Stroebel
- Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin
| | - Di Lang
- Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin
| | - Alexey V Glukhov
- Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin.
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Shen X, Zhang L, Jiang L, Xiong W, Tang Y, Lin L, Yu T. Alteration of sphingosine-1-phosphate with aging induces contractile dysfunction of colonic smooth muscle cells via Ca 2+ -activated K + channel (BK Ca ) upregulation. Neurogastroenterol Motil 2021; 33:e14052. [PMID: 33452855 DOI: 10.1111/nmo.14052] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Revised: 10/13/2020] [Accepted: 11/13/2020] [Indexed: 02/04/2023]
Abstract
BACKGROUND Age-associated changes alter calcium-activated potassium channel (BKCa ) expression of colon. Sphingolipids (SLs) are important cell membrane structural components; altered composition of SLs may affect BKCa expression. This study investigated the mechanism by which sphingosine-1-phosphate (S1P) contributes to age-associated contractile dysfunction. METHODS Fifty male Sprague Dawley rats of different ages were randomly assigned to five age-groups, namely 3, 6, 12, 18, and 24 months. BKCa expression, S1P levels, and phosphorylated myosin light chain (p-MLC) levels were tested in colonic tissues. In the absence and presence of S1P treatment, BKCa expression, p-MLC levels, and intracellular calcium mobilization were tested in vitro. BKCa small interfering RNA (siRNA) was used to investigate whether p-MLC expression and calcium mobilization were affected by BKCa in colonic smooth muscle cells (SMCs). The expressions of phosphorylated protein kinase B, c-Jun N-terminal kinases (JNKs), extracellular-regulated protein kinases, nuclear factor kappa-B (NF-κB), and protein kinase Cζ (PKCζ ) were examined to investigate the correlation between S1P and BKCa . KEY RESULTS Sphingosine-1-phosphate levels and sphingosine-1-phosphate receptor 2 (S1PR2) and BKCa expressions were upregulated and p-MLC expression was downregulated in the colonic tissues, age dependently. In the cultured SMCs, S1P treatment increased BKCa expression and reduced calcium concentration and p-MLC was observed. BKCa siRNA increased calcium concentration, and p-MLC levels significantly compared with control. We also showed that S1P upregulated BKCa through PKCζ , JNK, and NF-κB pathways. CONCLUSIONS AND INFERENCES In conclusion, S1P and S1PR2 participate in age-associated contractile dysfunction via BKCa upregulation through PKCζ , JNK, and NF-κB pathways.
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Affiliation(s)
- Xiaoxue Shen
- Department of Gastroenterology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Ling Zhang
- Department of Gastroenterology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Ling Jiang
- Department of Gastroenterology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Wenjie Xiong
- Department of Gastroenterology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Yurong Tang
- Department of Gastroenterology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Lin Lin
- Department of Gastroenterology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Ting Yu
- Department of Gastroenterology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
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Saeki T, Suzuki Y, Yamamura H, Takeshima H, Imaizumi Y. A junctophilin-caveolin interaction enables efficient coupling between ryanodine receptors and BK Ca channels in the Ca 2+ microdomain of vascular smooth muscle. J Biol Chem 2019; 294:13093-13105. [PMID: 31308177 PMCID: PMC6721949 DOI: 10.1074/jbc.ra119.008342] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Revised: 07/09/2019] [Indexed: 01/09/2023] Open
Abstract
Functional coupling between large-conductance Ca2+-activated K+ (BKCa) channels in the plasma membrane (PM) and ryanodine receptors (RyRs) in the sarcoplasmic reticulum (SR) is an essential mechanism for regulating mechanical force in most smooth muscle (SM) tissues. Spontaneous Ca2+ release through RyRs (Ca2+ sparks) and subsequent BKCa channel activation occur within the PM-SR junctional sites. We report here that a molecular interaction of caveolin-1 (Cav1), a caveola-forming protein, with junctophilin-2 (JP2), a bridging protein between PM and SR, positions BKCa channels near RyRs in SM cells (SMCs) and thereby contributes to the formation of a molecular complex essential for Ca2+ microdomain function. Approximately half of all Ca2+ sparks occurred within a close distance (<400 nm) from fluorescently labeled JP2 or Cav1 particles, when they were moderately expressed in primary SMCs from mouse mesenteric artery. The removal of caveolae by genetic Cav1 ablation or methyl-β-cyclodextrin treatments significantly reduced coupling efficiency between Ca2+ sparks and BKCa channel activity in SMCs, an effect also observed after JP2 knockdown in SMCs. A 20-amino acid-long region in JP2 appeared to be essential for the observed JP2-Cav1 interaction, and we also observed an interaction between JP2 and the BKCa channel. It can be concluded that the JP2-Cav1 interaction provides a structural and functional basis for the Ca2+ microdomain at PM-SR junctions and mediates cross-talk between RyRs and BKCa channels, converts local Ca2+ sparks into membrane hyperpolarization, and contributes to stabilizing resting tone in SMCs.
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Affiliation(s)
- Takanori Saeki
- Department of Molecular and Cellular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya 467-8603, Japan
| | - Yoshiaki Suzuki
- Department of Molecular and Cellular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya 467-8603, Japan
| | - Hisao Yamamura
- Department of Molecular and Cellular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya 467-8603, Japan
| | - Hiroshi Takeshima
- Department of Biological Chemistry, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan
| | - Yuji Imaizumi
- Department of Molecular and Cellular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya 467-8603, Japan.
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Suzuki Y, Ohya S, Yamamura H, Giles WR, Imaizumi Y. A New Splice Variant of Large Conductance Ca2+-activated K+ (BK) Channel α Subunit Alters Human Chondrocyte Function. J Biol Chem 2016; 291:24247-24260. [PMID: 27758860 DOI: 10.1074/jbc.m116.743302] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2016] [Revised: 10/06/2016] [Indexed: 02/06/2023] Open
Abstract
Large conductance Ca2+-activated K+ (BK) channels play essential roles in both excitable and non-excitable cells. For example, in chondrocytes, agonist-induced Ca2+ release from intracellular store activates BK channels, and this hyperpolarizes these cells, augments Ca2+ entry, and forms a positive feed-back mechanism for Ca2+ signaling and stimulation-secretion coupling. In the present study, functional roles of a newly identified splice variant in the BK channel α subunit (BKαΔe2) were examined in a human chondrocyte cell line, OUMS-27, and in a HEK293 expression system. Although BKαΔe2 lacks exon2, which codes the intracellular S0-S1 linker (Glu-127-Leu-180), significant expression was detected in several tissues from humans and mice. Molecular image analyses revealed that BKαΔe2 channels are not expressed on plasma membrane but can traffic to the plasma membrane after forming hetero-tetramer units with wild-type BKα (BKαWT). Single-channel current analyses demonstrated that BKα hetero-tetramers containing one, two, or three BKαΔe2 subunits are functional. These hetero-tetramers have a smaller single channel conductance and exhibit lower trafficking efficiency than BKαWT homo-tetramers in a stoichiometry-dependent manner. Site-directed mutagenesis of residues in exon2 identified Helix2 and the linker to S1 (Trp-158-Leu-180, particularly Arg-178) as an essential segment for channel function including voltage dependence and trafficking. BKαΔe2 knockdown in OUMS-27 chondrocytes increased BK current density and augmented the responsiveness to histamine assayed as cyclooxygenase-2 gene expression. These findings provide significant new evidence that BKαΔe2 can modulate cellular responses to physiological stimuli in human chondrocyte and contribute under pathophysiological conditions, such as osteoarthritis.
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Affiliation(s)
- Yoshiaki Suzuki
- From the Department of Molecular and Cellular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabedori, Mizuhoku, Nagoya 467-8603, Japan
| | - Susumu Ohya
- From the Department of Molecular and Cellular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabedori, Mizuhoku, Nagoya 467-8603, Japan.,the Department of Pharmacology, Division of Pathological Sciences, Kyoto Pharmaceutical University, Kyoto 607-8414, Japan, and
| | - Hisao Yamamura
- From the Department of Molecular and Cellular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabedori, Mizuhoku, Nagoya 467-8603, Japan
| | - Wayne R Giles
- the Faculties of Kinesiology and Medicine, University of Calgary, Calgary, Alberta T2N 1N4, Canada
| | - Yuji Imaizumi
- From the Department of Molecular and Cellular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabedori, Mizuhoku, Nagoya 467-8603, Japan,
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Screening and identification of proteins interacting with IL-24 by the yeast two-hybrid screen, Co-IP, and FRET assays. Anticancer Drugs 2016; 27:318-27. [PMID: 26930462 DOI: 10.1097/cad.0000000000000343] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Interleukin-24 (IL-24) is an ideal tumor-suppressor gene, but the mechanisms underlying its antitumor specificity remain to be elucidated. The best way to investigate these problems is to begin from the initiation of corresponding signaling cascades activated by IL-24 with screening and identifying those proteins that interacted with IL-24. With the aim of identifying these initial interactions, a yeast two-hybrid screening was performed by transforming AH109 cells containing PGBKT7-IL-24 with a liver cDNA plasmid library. These cells were then plated on synthetic nutrient medium (SD/-Trp/-Leu/-His) for the first screening and on quadruple dropout medium containing X-α-gal for the second screening. Positive colonies were further verified by repeating the MATE experiments, co-immunoprecipitation (Co-IP) analysis, and fluorescence resonance energy transfer (FRET) assays in vitro. Following the yeast two-hybrid screening, 15 genes were selected for sequencing, with two genes, HLA-C and NDUFA13, further verified using Co-IP assays and FRET assays. Both HLA-C and NDUFA13 were found to interact with IL-24. We found that HLA-C and NDUFA13 could interact with IL-24 and it may be involved in the signal induced by IL-24. Overall, this study contributes further insight into the cancer-specific apoptosis-inducing abilities of IL-24 to potentially enhance its therapeutic potential, and it also provides outlets for other biological functions of IL-24.
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Feng J, Hu Z, Chen H, Hua J, Wu R, Dong Z, Qiang L, Liu Y, Baas PW, Liu M. Depletion of kinesin-12, a myosin-IIB-interacting protein, promotes migration of cortical astrocytes. J Cell Sci 2016; 129:2438-47. [PMID: 27170353 DOI: 10.1242/jcs.181867] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Accepted: 05/04/2016] [Indexed: 01/21/2023] Open
Abstract
Kinesin-12 (also named Kif15) participates in important events during neuronal development, such as cell division of neuronal precursors, migration of young neurons and establishment of axons and dendritic arbors, by regulating microtubule organization. Little is known about the molecular mechanisms behind the functions of kinesin-12, and even less is known about its roles in other cell types of the nervous system. Here, we show that kinesin-12 depletion from cultured rat cortical astrocytes decreases cell proliferation but increases migration. Co-immunoprecipitation, GST pulldown and small interfering RNA (siRNA) experiments indicated that kinesin-12 directly interacts with myosin-IIB through their tail domains. Immunofluorescence analyses indicated that kinesin-12 and myosin-IIB colocalize in the lamellar region of astrocytes, and fluorescence resonance energy transfer analyses revealed an interaction between the two. The phosphorylation at Thr1142 of kinesin-12 was vital for their interaction. Loss of their interaction through expression of a phosphorylation mutant of kinesin-12 promoted astrocyte migration. We suggest that kinesin-12 and myosin-IIB can form a hetero-oligomer that generates force to integrate microtubules and actin filaments in certain regions of cells, and in the case of astrocytes, that this interaction can modulate their migration.
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Affiliation(s)
- Jie Feng
- Jiangsu Key Laboratory of Neuroregeneration, Co-innovation Center of Neuroregeneration, Nantong University, Nantong Jiangsu 226001, China
| | - Zunlu Hu
- Jiangsu Key Laboratory of Neuroregeneration, Co-innovation Center of Neuroregeneration, Nantong University, Nantong Jiangsu 226001, China
| | - Haijiao Chen
- Jiangsu Key Laboratory of Neuroregeneration, Co-innovation Center of Neuroregeneration, Nantong University, Nantong Jiangsu 226001, China
| | - Juan Hua
- Jiangsu Key Laboratory of Neuroregeneration, Co-innovation Center of Neuroregeneration, Nantong University, Nantong Jiangsu 226001, China
| | - Ronghua Wu
- Jiangsu Key Laboratory of Neuroregeneration, Co-innovation Center of Neuroregeneration, Nantong University, Nantong Jiangsu 226001, China
| | - Zhangji Dong
- Jiangsu Key Laboratory of Neuroregeneration, Co-innovation Center of Neuroregeneration, Nantong University, Nantong Jiangsu 226001, China
| | - Liang Qiang
- Jiangsu Key Laboratory of Neuroregeneration, Co-innovation Center of Neuroregeneration, Nantong University, Nantong Jiangsu 226001, China Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA 19129, USA
| | - Yan Liu
- Jiangsu Key Laboratory of Neuroregeneration, Co-innovation Center of Neuroregeneration, Nantong University, Nantong Jiangsu 226001, China
| | - Peter W Baas
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA 19129, USA
| | - Mei Liu
- Jiangsu Key Laboratory of Neuroregeneration, Co-innovation Center of Neuroregeneration, Nantong University, Nantong Jiangsu 226001, China
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7
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Protein Network Interacting with BK Channels. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2016; 128:127-61. [DOI: 10.1016/bs.irn.2016.03.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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Choi S, Kim JA, Kim TH, Li H, Shin K, Lee Y, Oh S, Pewzner‐Jung Y, Futerman AH, Suh SH. Altering sphingolipid composition with aging induces contractile dysfunction of gastric smooth muscle via K(Ca) 1.1 upregulation. Aging Cell 2015; 14:982-94. [PMID: 26288989 PMCID: PMC4693452 DOI: 10.1111/acel.12388] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/19/2015] [Indexed: 01/16/2023] Open
Abstract
KCa1.1 regulates smooth muscle contractility by modulating membrane potential, and age‐associated changes in KCa1.1 expression may contribute to the development of motility disorders of the gastrointestinal tract. Sphingolipids (SLs) are important structural components of cellular membranes whose altered composition may affect KCa1.1 expression. Thus, in this study, we examined whether altered SL composition due to aging may affect the contractility of gastric smooth muscle (GSM). We studied changes in ceramide synthases (CerS) and SL levels in the GSM of mice of varying ages and compared them with those in young CerS2‐null mice. The levels of C16‐ and C18‐ceramides, sphinganine, sphingosine, and sphingosine 1‐phosphate were increased, and levels of C22, C24:1 and C24 ceramides were decreased in the GSM of both aged wild‐type and young CerS2‐null mice. The altered SL composition upregulated KCa1.1 and increased KCa1.1 currents, while no change was observed in KCa1.1 channel activity. The upregulation of KCa1.1 impaired intracellular Ca2+ mobilization and decreased phosphorylated myosin light chain levels, causing GSM contractile dysfunction. Additionally, phosphoinositide 3‐kinase, protein kinase Cζ, c‐Jun N‐terminal kinases, and nuclear factor kappa‐B were found to be involved in KCa1.1 upregulation. Our findings suggest that age‐associated changes in SL composition or CerS2 ablation upregulate KCa1.1 via the phosphoinositide 3‐kinase/protein kinase Cζ/c‐Jun N‐terminal kinases/nuclear factor kappa‐B‐mediated pathway and impair Ca2+ mobilization, which thereby induces the contractile dysfunction of GSM. CerS2‐null mice exhibited similar effects to aged wild‐type mice; therefore, CerS2‐null mouse models may be utilized for investigating the pathogenesis of aging‐associated motility disorders.
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Affiliation(s)
- Shinkyu Choi
- Department of Physiology Medical School Ewha Womans University Seoul Korea
| | - Ji Aee Kim
- Department of Physiology Medical School Ewha Womans University Seoul Korea
| | - Tae Hun Kim
- Department of Internal Medicine Medical School Ewha Womans University Seoul Korea
| | - Hai‐yan Li
- Department of Physiology Medical School Ewha Womans University Seoul Korea
| | - Kyong‐Oh Shin
- College of Pharmacy and MRC Chungbuk National University Chongju Korea
| | - Yong‐Moon Lee
- College of Pharmacy and MRC Chungbuk National University Chongju Korea
| | - Seikwan Oh
- Department of Molecular Medicine Medical School Ewha Womans University Seoul Korea
| | - Yael Pewzner‐Jung
- Department of Biological Chemistry Weizmann Institute of Science Rehovot Israel
| | - Anthony H. Futerman
- Department of Biological Chemistry Weizmann Institute of Science Rehovot Israel
| | - Suk Hyo Suh
- Department of Physiology Medical School Ewha Womans University Seoul Korea
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9
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Yamamura H, Suzuki Y, Imaizumi Y. New light on ion channel imaging by total internal reflection fluorescence (TIRF) microscopy. J Pharmacol Sci 2015; 128:1-7. [PMID: 26002253 DOI: 10.1016/j.jphs.2015.04.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2015] [Revised: 03/30/2015] [Accepted: 04/06/2015] [Indexed: 11/28/2022] Open
Abstract
Ion channels play pivotal roles in a wide variety of cellular functions; therefore, their physiological characteristics, pharmacological responses, and molecular structures have been extensively investigated. However, the mobility of an ion channel itself in the cell membrane has not been examined in as much detail. A total internal reflection fluorescence (TIRF) microscope allows fluorophores to be imaged in a restricted region within an evanescent field of less than 200 nm from the interface of the coverslip and plasma membrane in living cells. Thus the TIRF microscope is useful for selectively visualizing the plasmalemmal surface and subplasmalemmal zone. In this review, we focused on a single-molecule analysis of the dynamic movement of ion channels in the plasma membrane using TIRF microscopy. We also described two single-molecule imaging techniques under TIRF microscopy: fluorescence resonance energy transfer (FRET) for the identification of molecules that interact with ion channels, and subunit counting for the determination of subunit stoichiometry in a functional channel. TIRF imaging can also be used to analyze spatiotemporal Ca(2+) events in the subplasmalemma. Single-molecule analyses of ion channels and localized Ca(2+) signals based on TIRF imaging provide beneficial pharmacological and physiological information concerning the functions of ion channels.
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Affiliation(s)
- Hisao Yamamura
- Department of Molecular & Cellular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya 467-8603, Japan.
| | - Yoshiaki Suzuki
- Department of Molecular & Cellular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya 467-8603, Japan
| | - Yuji Imaizumi
- Department of Molecular & Cellular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya 467-8603, Japan
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10
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Devauges V, Matthews DR, Aluko J, Nedbal J, Levitt JA, Poland SP, Coban O, Weitsman G, Monypenny J, Ng T, Ameer-Beg SM. Steady-state acceptor fluorescence anisotropy imaging under evanescent excitation for visualisation of FRET at the plasma membrane. PLoS One 2014; 9:e110695. [PMID: 25360776 PMCID: PMC4215982 DOI: 10.1371/journal.pone.0110695] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Accepted: 09/15/2014] [Indexed: 11/22/2022] Open
Abstract
We present a novel imaging system combining total internal reflection fluorescence (TIRF) microscopy with measurement of steady-state acceptor fluorescence anisotropy in order to perform live cell Förster Resonance Energy Transfer (FRET) imaging at the plasma membrane. We compare directly the imaging performance of fluorescence anisotropy resolved TIRF with epifluorescence illumination. The use of high numerical aperture objective for TIRF required correction for induced depolarization factors. This arrangement enabled visualisation of conformational changes of a Raichu-Cdc42 FRET biosensor by measurement of intramolecular FRET between eGFP and mRFP1. Higher activity of the probe was found at the cell plasma membrane compared to intracellularly. Imaging fluorescence anisotropy in TIRF allowed clear differentiation of the Raichu-Cdc42 biosensor from negative control mutants. Finally, inhibition of Cdc42 was imaged dynamically in live cells, where we show temporal changes of the activity of the Raichu-Cdc42 biosensor.
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Affiliation(s)
- Viviane Devauges
- Richard Dimbleby Cancer Research Laboratory, Division of Cancer Studies and Randall Division of Cell and Molecular Biophysics, King's College London, London, United Kingdom
| | - Daniel R. Matthews
- Richard Dimbleby Cancer Research Laboratory, Division of Cancer Studies and Randall Division of Cell and Molecular Biophysics, King's College London, London, United Kingdom
| | - Justin Aluko
- Department of Physics, King's College London, London, United Kingdom
| | - Jakub Nedbal
- Richard Dimbleby Cancer Research Laboratory, Division of Cancer Studies and Randall Division of Cell and Molecular Biophysics, King's College London, London, United Kingdom
| | - James A. Levitt
- Richard Dimbleby Cancer Research Laboratory, Division of Cancer Studies and Randall Division of Cell and Molecular Biophysics, King's College London, London, United Kingdom
| | - Simon P. Poland
- Richard Dimbleby Cancer Research Laboratory, Division of Cancer Studies and Randall Division of Cell and Molecular Biophysics, King's College London, London, United Kingdom
| | - Oana Coban
- Richard Dimbleby Cancer Research Laboratory, Division of Cancer Studies and Randall Division of Cell and Molecular Biophysics, King's College London, London, United Kingdom
| | - Gregory Weitsman
- Richard Dimbleby Cancer Research Laboratory, Division of Cancer Studies and Randall Division of Cell and Molecular Biophysics, King's College London, London, United Kingdom
| | - James Monypenny
- Richard Dimbleby Cancer Research Laboratory, Division of Cancer Studies and Randall Division of Cell and Molecular Biophysics, King's College London, London, United Kingdom
| | - Tony Ng
- Richard Dimbleby Cancer Research Laboratory, Division of Cancer Studies and Randall Division of Cell and Molecular Biophysics, King's College London, London, United Kingdom
- UCL Cancer Institute, University College London, London, United Kingdom
| | - Simon M. Ameer-Beg
- Richard Dimbleby Cancer Research Laboratory, Division of Cancer Studies and Randall Division of Cell and Molecular Biophysics, King's College London, London, United Kingdom
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11
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Suzuki Y, Yamamura H, Ohya S, Imaizumi Y. Caveolin-1 facilitates the direct coupling between large conductance Ca2+-activated K+ (BKCa) and Cav1.2 Ca2+ channels and their clustering to regulate membrane excitability in vascular myocytes. J Biol Chem 2013; 288:36750-61. [PMID: 24202214 DOI: 10.1074/jbc.m113.511485] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
L-type voltage-dependent Ca(2+) channels (LVDCC) and large conductance Ca(2+)-activated K(+) channels (BKCa) are the major factors defining membrane excitability in vascular smooth muscle cells (VSMCs). The Ca(2+) release from sarcoplasmic reticulum through ryanodine receptor significantly contributes to BKCa activation in VSMCs. In this study direct coupling between LVDCC (Cav1.2) and BKCa and the role of caveoline-1 on their interaction in mouse mesenteric artery SMCs were examined. The direct activation of BKCa by Ca(2+) influx through coupling LVDCC was demonstrated by patch clamp recordings in freshly isolated VSMCs. Using total internal reflection fluorescence microscopy, it was found that a large part of yellow fluorescent protein-tagged BKCa co-localized with the cyan fluorescent protein-tagged Cav1.2 expressed in the plasma membrane of primary cultured mouse VSMCs and that the two molecules often exhibited FRET. It is notable that each BKα subunit of a tetramer in BKCa can directly interact with Cav1.2 and promotes Cav1.2 cluster in the molecular complex. Furthermore, caveolin-1 deficiency in knock-out (KO) mice significantly reduced not only the direct coupling between BKCa and Cav1.2 but also the functional coupling between BKCa and ryanodine receptor in VSMCs. The measurement of single cell shortening by 40 mm K(+) revealed enhanced contractility in VSMCs from KO mice than wild type. Taken together, caveolin-1 facilitates the accumulation/clustering of BKCa-LVDCC complex in caveolae, which effectively regulates spatiotemporal Ca(2+) dynamics including the negative feedback, to control the arterial excitability and contractility.
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Affiliation(s)
- Yoshiaki Suzuki
- From the Department of Molecular and Cellular Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya 467-8603, Japan and
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