1
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Ballit A, Dao TT. Multiphysics and multiscale modeling of uterine contractions: integrating electrical dynamics and soft tissue deformation with fiber orientation. Med Biol Eng Comput 2024; 62:791-816. [PMID: 38008805 DOI: 10.1007/s11517-023-02962-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Accepted: 10/28/2023] [Indexed: 11/28/2023]
Abstract
The development of a comprehensive uterine model that seamlessly integrates the intricate interactions between the electrical and mechanical aspects of uterine activity could potentially facilitate the prediction and management of labor complications. Such a model has the potential to enhance our understanding of the initiation and synchronization mechanisms involved in uterine contractions, providing a more profound comprehension of the factors associated with labor complications, including preterm labor. Consequently, it has the capacity to assist in more effective preparation and intervention strategies for managing such complications. In this study, we present a computational model that effectively integrates the electrical and mechanical components of uterine contractions. By combining a state-of-the-art electrical model with the Hyperelastic Mass-Spring Model (HyperMSM), we adopt a multiphysics and multiscale approach to capture the electrical and mechanical activities within the uterus. The electrical model incorporates the generation and propagation of action potentials, while the HyperMSM simulates the mechanical behavior and deformations of the uterine tissue. Notably, our model takes into account the orientation of muscle fibers, ensuring that the simulated contractions align with their inherent directional characteristics. One noteworthy aspect of our contraction model is its novel approach to scaling the rest state of the mesh elements, as opposed to the conventional method of applying mechanical loads. By doing so, we eliminate artificial strain energy resulting from the resistance of soft tissues' elastic properties during contractions. We validated our proposed model through test simulations, demonstrating its feasibility and its ability to reproduce expected contraction patterns across different mesh resolutions and configurations. Moving forward, future research efforts should prioritize the validation of our model using robust clinical data. Additionally, it is crucial to refine the model by incorporating a more realistic uterus model derived from medical imaging. Furthermore, applying the model to simulate the entire childbirth process holds immense potential for gaining deeper insights into the intricate dynamics of labor.
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Affiliation(s)
- Abbass Ballit
- Univ. Lille, CNRS, Centrale Lille, UMR 9013 LaMcube - Laboratoire de Mécanique, Multiphysique, Multiéchelle, 59000, Lille, France
| | - Tien-Tuan Dao
- Univ. Lille, CNRS, Centrale Lille, UMR 9013 LaMcube - Laboratoire de Mécanique, Multiphysique, Multiéchelle, 59000, Lille, France.
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2
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Seime T, van Wanrooij M, Karlöf E, Kronqvist M, Johansson S, Matic L, Gasser TC, Hedin U. Biomechanical Assessment of Macro-Calcification in Human Carotid Atherosclerosis and Its Impact on Smooth Muscle Cell Phenotype. Cells 2022; 11:3279. [PMID: 36291144 PMCID: PMC9600867 DOI: 10.3390/cells11203279] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Revised: 10/14/2022] [Accepted: 10/17/2022] [Indexed: 12/13/2023] Open
Abstract
Intimal calcification and vascular stiffening are predominant features of end-stage atherosclerosis. However, their role in atherosclerotic plaque instability and how the extent and spatial distribution of calcification influence plaque biology remain unclear. We recently showed that extensive macro calcification can be a stabilizing feature of late-stage human lesions, associated with a reacquisition of more differentiated properties of plaque smooth muscle cells (SMCs) and extracellular matrix (ECM) remodeling. Here, we hypothesized that biomechanical forces related to macro-calcification within plaques influence SMC phenotype and contribute to plaque stabilization. We generated a finite element modeling (FEM) pipeline to assess plaque tissue stretch based on image analysis of preoperative computed tomography angiography (CTA) of carotid atherosclerotic plaques to visualize calcification and soft tissues (lipids and extracellular matrix) within the lesions. Biomechanical stretch was significantly reduced in tissues in close proximity to macro calcification, while increased levels were observed within distant soft tissues. Applying this data to an in vitro stretch model on primary vascular SMCs revealed upregulation of typical markers for differentiated SMCs and contractility under low stretch conditions but also impeded SMC alignment. In contrast, high stretch conditions in combination with calcifying conditions induced SMC apoptosis. Our findings suggest that the load bearing capacities of macro calcifications influence SMC differentiation and survival and contribute to atherosclerotic plaque stabilization.
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Affiliation(s)
- Till Seime
- Vascular Surgery, Department of Molecular Medicine and Surgery, Karolinska Institute, 17164 Stockholm, Sweden
| | - Max van Wanrooij
- Solid Mechanics, School of Engineering Sciences, KTH Royal Institute of Technology, 10044 Stockholm, Sweden
| | - Eva Karlöf
- Vascular Surgery, Department of Molecular Medicine and Surgery, Karolinska Institute, 17164 Stockholm, Sweden
| | - Malin Kronqvist
- Vascular Surgery, Department of Molecular Medicine and Surgery, Karolinska Institute, 17164 Stockholm, Sweden
| | - Staffan Johansson
- Biochemistry & Cell & Tumor Biology, Department of Medical Biochemistry and Microbiology, Uppsala University, 75123 Uppsala, Sweden
| | - Ljubica Matic
- Vascular Surgery, Department of Molecular Medicine and Surgery, Karolinska Institute, 17164 Stockholm, Sweden
| | - T. Christian Gasser
- Solid Mechanics, School of Engineering Sciences, KTH Royal Institute of Technology, 10044 Stockholm, Sweden
| | - Ulf Hedin
- Vascular Surgery, Department of Molecular Medicine and Surgery, Karolinska Institute, 17164 Stockholm, Sweden
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3
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Dixon RE, Navedo MF, Binder MD, Santana LF. Mechanisms and Physiological Implications of Cooperative Gating of Ion Channels Clusters. Physiol Rev 2021; 102:1159-1210. [PMID: 34927454 DOI: 10.1152/physrev.00022.2021] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Ion channels play a central role in the regulation of nearly every cellular process. Dating back to the classic 1952 Hodgkin-Huxley model of the generation of the action potential, ion channels have always been thought of as independent agents. A myriad of recent experimental findings exploiting advances in electrophysiology, structural biology, and imaging techniques, however, have posed a serious challenge to this long-held axiom as several classes of ion channels appear to open and close in a coordinated, cooperative manner. Ion channel cooperativity ranges from variable-sized oligomeric cooperative gating in voltage-gated, dihydropyridine-sensitive Cav1.2 and Cav1.3 channels to obligatory dimeric assembly and gating of voltage-gated Nav1.5 channels. Potassium channels, transient receptor potential channels, hyperpolarization cyclic nucleotide-activated channels, ryanodine receptors (RyRs), and inositol trisphosphate receptors (IP3Rs) have also been shown to gate cooperatively. The implications of cooperative gating of these ion channels range from fine tuning excitation-contraction coupling in muscle cells to regulating cardiac function and vascular tone, to modulation of action potential and conduction velocity in neurons and cardiac cells, and to control of pace-making activity in the heart. In this review, we discuss the mechanisms leading to cooperative gating of ion channels, their physiological consequences and how alterations in cooperative gating of ion channels may induce a range of clinically significant pathologies.
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Affiliation(s)
- Rose Ellen Dixon
- Department of Physiology and Membrane Biology, University of California, Davis, CA, United States
| | - Manuel F Navedo
- Department of Pharmacology, University of California, Davis, CA, United States
| | - Marc D Binder
- Department of Physiology and Biophysics, University of Washington, Seattle, WA, United States
| | - L Fernando Santana
- Department of Physiology and Membrane Biology, University of California, Davis, CA, United States
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4
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Joshi V, Strege PR, Farrugia G, Beyder A. Mechanotransduction in gastrointestinal smooth muscle cells: role of mechanosensitive ion channels. Am J Physiol Gastrointest Liver Physiol 2021; 320:G897-G906. [PMID: 33729004 PMCID: PMC8202201 DOI: 10.1152/ajpgi.00481.2020] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Mechanosensation, the ability to properly sense mechanical stimuli and transduce them into physiologic responses, is an essential determinant of gastrointestinal (GI) function. Abnormalities in this process result in highly prevalent GI functional and motility disorders. In the GI tract, several cell types sense mechanical forces and transduce them into electrical signals, which elicit specific cellular responses. Some mechanosensitive cells like sensory neurons act as specialized mechanosensitive cells that detect forces and transduce signals into tissue-level physiological reactions. Nonspecialized mechanosensitive cells like smooth muscle cells (SMCs) adjust their function in response to forces. Mechanosensitive cells use various mechanoreceptors and mechanotransducers. Mechanoreceptors detect and convert force into electrical and biochemical signals, and mechanotransducers amplify and direct mechanoreceptor responses. Mechanoreceptors and mechanotransducers include ion channels, specialized cytoskeletal proteins, cell junction molecules, and G protein-coupled receptors. SMCs are particularly important due to their role as final effectors for motor function. Myogenic reflex-the ability of smooth muscle to contract in response to stretch rapidly-is a critical smooth muscle function. Such rapid mechanotransduction responses rely on mechano-gated and mechanosensitive ion channels, which alter their ion pores' opening in response to force, allowing fast electrical and Ca2+ responses. Although GI SMCs express a variety of such ion channels, their identities remain unknown. Recent advancements in electrophysiological, genetic, in vivo imaging, and multi-omic technologies broaden our understanding of how SMC mechano-gated and mechanosensitive ion channels regulate GI functions. This review discusses GI SMC mechanosensitivity's current developments with a particular emphasis on mechano-gated and mechanosensitive ion channels.
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Affiliation(s)
- Vikram Joshi
- 1Division of Gastroenterology & Hepatology, Enteric NeuroScience Program (ENSP), Mayo Clinic, Rochester, Minnesota
| | - Peter R. Strege
- 1Division of Gastroenterology & Hepatology, Enteric NeuroScience Program (ENSP), Mayo Clinic, Rochester, Minnesota
| | - Gianrico Farrugia
- 1Division of Gastroenterology & Hepatology, Enteric NeuroScience Program (ENSP), Mayo Clinic, Rochester, Minnesota,2Department of Physiology & Biomedical Engineering, Mayo Clinic, Rochester, Minnesota
| | - Arthur Beyder
- 1Division of Gastroenterology & Hepatology, Enteric NeuroScience Program (ENSP), Mayo Clinic, Rochester, Minnesota,2Department of Physiology & Biomedical Engineering, Mayo Clinic, Rochester, Minnesota
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5
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Parperis C, Wallace MI. Single-molecule imaging of pore-forming toxin dynamics in droplet interface bilayers. Methods Enzymol 2021; 649:431-459. [PMID: 33712195 DOI: 10.1016/bs.mie.2021.01.035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Single-channel recording from pore-forming toxins (PFTs) provides a clear and direct molecular readout of toxin action. However to complete any mechanistic understanding of PFT behavior, this functional kinetic readout must be linked to the underlying changes in toxin structure, binding, conformation, or stoichiometry. Here we review how single-molecule imaging methods might be used to further our understanding of PFTs, and provide detailed practical guidance on the use of droplet interface bilayers as a method capable of examining both single-molecule fluorescence and single-channel electrical signals from PFTs.
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Affiliation(s)
- Christopher Parperis
- Department of Chemistry, Britannia House, King's College London, London, United Kingdom
| | - Mark I Wallace
- Department of Chemistry, Britannia House, King's College London, London, United Kingdom.
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6
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Zhao M, Chen J, Jin H, Qi Z. Extracellular Ca 2+ induces desensitized cytosolic Ca 2+ rise sensitive to phospholipase C inhibitor which suppresses root growth with Ca 2+ dependence. JOURNAL OF PLANT PHYSIOLOGY 2020; 252:153190. [PMID: 32688165 DOI: 10.1016/j.jplph.2020.153190] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2020] [Revised: 05/04/2020] [Accepted: 05/09/2020] [Indexed: 06/11/2023]
Abstract
Calcium (Ca) is an essential element for all organisms. In animal cells, the plasma membrane-localized Ca receptor CaSR coupled to a phospholipase C (PLC)-dependent signaling cascade monitors extracellular Ca2+ concentrations ([Ca2+]ext) and responds with increases in cytosolic calcium concentrations ([Ca2+]cyt). Plant roots encounter variable soil conditions, but how they sense changes in [Ca2+]ext is largely unknown. In this study, we demonstrate that increasing [Ca2+]ext evokes a transient increase in [Ca2+] in the cytosol, mitochondria, and nuclei of Arabidopsis thaliana root cells. These increases were strongly desensitized to repeat applications of [Ca2+]ext, a typical feature of receptor-mediated cellular signaling in animal and plant cells. Treatment with gadolinium (Gd3+), a CaSR activator in animal cells, induced concentration-dependent increases in [Ca2+]cyt in roots, which showed self-desensitization and cross-desensitization to [Ca2+]ext-induced increases in [Ca2+]cyt (EICC). EICC was sensitive to extracellular H+, K+, Na+, and Mg2+ levels. Treatment with the PLC inhibitor neomycin suppressed EICC and Ca accumulation in roots. The inhibitory effect of neomycin on root elongation was fully rescued by increasing [Ca2+]ext but not [Mg2+] or [K+] in the growth medium. These results suggest that [Ca2+]ext and the movement of Ca2+ into the cytosol of plant roots are regulated by a receptor-mediated signaling pathway involving PLC.
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Affiliation(s)
- Man Zhao
- Key Laboratory of Forage and Endemic Crop Biotechnology, Ministry of Education, School of Life Sciences, Inner Mongolia University, Hohhot, 010071, PR China; State Key Laboratory of Reproductive Regulatory and Breeding of Grassland Livestock, Inner Mongolia University, Hohhot, 010071, PR China
| | - Jianhua Chen
- Key Laboratory of Forage and Endemic Crop Biotechnology, Ministry of Education, School of Life Sciences, Inner Mongolia University, Hohhot, 010071, PR China; State Key Laboratory of Reproductive Regulatory and Breeding of Grassland Livestock, Inner Mongolia University, Hohhot, 010071, PR China
| | - Huiqing Jin
- Research Centre for Horticultural Science and Technology of Hohhot, Hohhot, 010020, PR China
| | - Zhi Qi
- Key Laboratory of Forage and Endemic Crop Biotechnology, Ministry of Education, School of Life Sciences, Inner Mongolia University, Hohhot, 010071, PR China; State Key Laboratory of Reproductive Regulatory and Breeding of Grassland Livestock, Inner Mongolia University, Hohhot, 010071, PR China.
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7
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Lopez JR, Uryash A, Faury G, Estève E, Adams JA. Contribution of TRPC Channels to Intracellular Ca 2 + Dyshomeostasis in Smooth Muscle From mdx Mice. Front Physiol 2020; 11:126. [PMID: 32153426 PMCID: PMC7044154 DOI: 10.3389/fphys.2020.00126] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Accepted: 02/04/2020] [Indexed: 12/17/2022] Open
Abstract
Duchenne muscular dystrophy (DMD) is an irreversible muscle disease characterized by a progressive loss of muscle function, decreased ambulation, and ultimately death as a result of cardiac or respiratory failure. DMD is caused by the lack of dystrophin, a protein that is important for membrane stability and signaling in excitable cells. Although vascular smooth muscle cells (VSMCs) dysfunction occurs in many pathological conditions, little is known about vascular smooth muscle function in DMD. We have previously shown that striated muscle cells, as well as neurons isolated from dystrophic (mdx) mice have higher intracellular Ca2+ ([Ca2+]i) and Na+ ([Na+]i) concentrations and decreased cell viability in comparison with wild type (Wt). Experiments were carried out in isolated VSMCs from mdx (a murine model of DMD) and congenic C57BL/10SnJ Wt mice. We found elevated [Ca2+]i and [Na+]i in VSMCs from mdx mice compared to Wt. Exposure to 1-oleoyl-2-acetyl-sn-glycerol (OAG), a TRPC3 and TRPC6 channel activator, induced a greater elevation of [Ca2+]i and [Na+]i in mdx than Wt VSMCs. The OAG induced increases in [Ca2+]i could be abolished by either removal of extracellular Ca2+ or by SAR7334, a blocker of TRPC3 and TRPC 6 channels in both genotypes. Mdx and Wt VSMCs were susceptible to muscle cell stretch-induced elevations of [Ca2+]i and [Na+]i which was completely inhibited by GsMTx-4, a mechanosensitive ion channel inhibitor. Western blots showed a significant upregulation of TRPC1 -3, -6 proteins in mdx VSMCs compare to age-matched Wt. The lack of dystrophin in mdx VSMCs produced a profound alteration of [Ca2+]i and [Na+]i homeostasis that appears to be mediated by TRPC channels. Moreover, we have been able to demonstrate pharmacologically that the enhanced stretch-induced elevation of intracellular [Ca2+] and concomitant cell damage in mdx VSMCs also appears to be mediated through TRPC1, -3 and -6 channel activation.
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Affiliation(s)
- Jose R Lopez
- Department of Research, Mount Sinai Medical Center, Miami, FL, United States
| | - Arkady Uryash
- Department of Neonatology, Mount Sinai Medical Center, Miami, FL, United States
| | - Gilles Faury
- HP2, CHU Grenoble Alpes, Inserm, University Grenoble Alpes, Grenoble, France
| | - Eric Estève
- HP2, CHU Grenoble Alpes, Inserm, University Grenoble Alpes, Grenoble, France
| | - Jose A Adams
- Department of Neonatology, Mount Sinai Medical Center, Miami, FL, United States
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8
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Li Y, Yu WK, Chen L, Chan YS, Liu D, Fong CC, Xu T, Zhu G, Sun D, Yang M. Electrotaxis of tumor-initiating cells of H1975 lung adenocarcinoma cells is associated with both activation of stretch-activated cation channels (SACCs) and internal calcium release. Bioelectrochemistry 2018; 124:80-92. [DOI: 10.1016/j.bioelechem.2018.03.013] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Revised: 03/24/2018] [Accepted: 03/26/2018] [Indexed: 12/13/2022]
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9
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Yochum M, Laforêt J, Marque C. Multi-scale and multi-physics model of the uterine smooth muscle with mechanotransduction. Comput Biol Med 2017; 93:17-30. [PMID: 29253628 DOI: 10.1016/j.compbiomed.2017.12.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2017] [Revised: 12/02/2017] [Accepted: 12/02/2017] [Indexed: 11/18/2022]
Abstract
Preterm labor is an important public health problem. However, the efficiency of the uterine muscle during labor is complex and still poorly understood. This work is a first step towards a model of the uterine muscle, including its electrical and mechanical components, to reach a better understanding of the uterus synchronization. This model is proposed to investigate, by simulation, the possible role of mechanotransduction for the global synchronization of the uterus. The electrical diffusion indeed explains the local propagation of contractile activity, while the tissue stretching may play a role in the synchronization of distant parts of the uterine muscle. This work proposes a multi-physics (electrical, mechanical) and multi-scales (cell, tissue, whole uterus) model, which is applied to a realistic uterus 3D mesh. This model includes electrical components at different scales: generation of action potentials at the cell level, electrical diffusion at the tissue level. It then links these electrical events to the mechanical behavior, at the cellular level (via the intracellular calcium concentration), by simulating the force generated by each active cell. It thus computes an estimation of the intra uterine pressure (IUP) by integrating the forces generated by each active cell at the whole uterine level, as well as the stretching of the tissue (by using a viscoelastic law for the behavior of the tissue). It finally includes at the cellular level stretch activated channels (SACs) that permit to create a loop between the mechanical and the electrical behavior (mechanotransduction). The simulation of different activated regions of the uterus, which in this first "proof of concept" case are electrically isolated, permits the activation of inactive regions through the stretching (induced by the electrically active regions) computed at the whole organ scale. This permits us to evidence the role of the mechanotransduction in the global synchronization of the uterus. The results also permit us to evidence the effect on IUP of this enhanced synchronization induced by the presence of SACs. This proposed simplified model will be further improved in order to permit a better understanding of the global uterine synchronization occurring during efficient labor contractions.
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Affiliation(s)
- Maxime Yochum
- Sorbonne University, Université de Technologie de Compiègne, CNRS UMR 7338, Biomechanics and Bioengineering, Centre de Recherche Royallieu, CS 60319-60203 Compiègne cedex, France.
| | - Jérémy Laforêt
- Sorbonne University, Université de Technologie de Compiègne, CNRS UMR 7338, Biomechanics and Bioengineering, Centre de Recherche Royallieu, CS 60319-60203 Compiègne cedex, France.
| | - Catherine Marque
- Sorbonne University, Université de Technologie de Compiègne, CNRS UMR 7338, Biomechanics and Bioengineering, Centre de Recherche Royallieu, CS 60319-60203 Compiègne cedex, France
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10
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Yang L, Wang L, Zhu C, Wu J, Yuan Y, Yu L, Xu Y, Xu J, Wang T, Liao Z, Wang S, Zhu X, Gao P, Zhang Y, Wang X, Jiang Q, Shu G. Laminarin counteracts diet-induced obesity associated with glucagon-like peptide-1 secretion. Oncotarget 2017; 8:99470-99481. [PMID: 29245916 PMCID: PMC5725107 DOI: 10.18632/oncotarget.19957] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Accepted: 06/16/2017] [Indexed: 01/13/2023] Open
Abstract
Laminarin, a type of β-glucan isolated from brown seaweeds, exhibits verity of physiological activities, which include immunology modulation and antitumor function. To investigate the effect of laminarin on energy homeostasis, mice were orally administrated with laminarin to test food intake, fat deposition, and glucose homeostasis. Chronically, laminarin treatment significantly decreases high-fat-diet-induced body weight gain and fat deposition and reduces blood glucose level and glucose tolerance. Acutely, laminarin enhances serum glucagon-like peptide-1 (GLP-1) content and the mRNA expression level of proglucagon and prohormone convertase 1 in ileum. Subsequently, laminarin suppresses the food intake of mice, the hypothalamic AgRP neuron activity, and AgRP expression but activates pancreatic function. Furthermore, laminarin-induced appetite reduction was totally blocked by Exendin (9-39), a specific competitive inhibitor of GLP-1 receptor. Then, STC-1 cells were adopted to address the underlying mechanism, by which laminarin promoted GLP-1 secretion in vitro. Results showed that laminarin dose-dependently promoted GLP-1 secretion and c-Fos protein expression in STC-1 cells, which were independent of Dectin-1 and CD18. Interestingly, BAPTA-AM, a calcium-chelating agent, potently attenuated laminarin-induced [Ca2+]i elevation, c-Fos expression, and GLP-1 secretion. In summary, our data support that laminarin counteracts diet-induced obesity and stimulates GLP-1 secretion via [Ca2+]i; this finding provides an experimental basis for laminarin application to treat obesity and maintain glucose homeostasis.
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Affiliation(s)
- Liusong Yang
- Guangdong Province Key Laboratory of Animal Nutritional Regulation, Guangzhou, Guangdong 510642, China
| | - Lina Wang
- Guangdong Province Key Laboratory of Animal Nutritional Regulation, Guangzhou, Guangdong 510642, China
| | - Canjun Zhu
- Guangdong Province Key Laboratory of Animal Nutritional Regulation, Guangzhou, Guangdong 510642, China
| | - Junguo Wu
- Guangdong Province Key Laboratory of Animal Nutritional Regulation, Guangzhou, Guangdong 510642, China
| | - Yexian Yuan
- Guangdong Province Key Laboratory of Animal Nutritional Regulation, Guangzhou, Guangdong 510642, China
| | - Lulu Yu
- Guangdong Province Key Laboratory of Animal Nutritional Regulation, Guangzhou, Guangdong 510642, China
| | - Yaqiong Xu
- Guangdong Province Key Laboratory of Animal Nutritional Regulation, Guangzhou, Guangdong 510642, China
| | - Jingren Xu
- Guangdong Province Key Laboratory of Animal Nutritional Regulation, Guangzhou, Guangdong 510642, China
| | - Tao Wang
- Guangdong Province Key Laboratory of Animal Nutritional Regulation, Guangzhou, Guangdong 510642, China
| | - Zhengrui Liao
- Guangdong Province Key Laboratory of Animal Nutritional Regulation, Guangzhou, Guangdong 510642, China
| | - Songbo Wang
- Guangdong Province Key Laboratory of Animal Nutritional Regulation, Guangzhou, Guangdong 510642, China.,South China Observation Experiment Station of Animal Nutrition and Feed Science, Ministry of Agriculture, Guangzhou, Guangdong 510642, China
| | - Xiaotong Zhu
- Guangdong Province Key Laboratory of Animal Nutritional Regulation, Guangzhou, Guangdong 510642, China
| | - Ping Gao
- Guangdong Province Key Laboratory of Animal Nutritional Regulation, Guangzhou, Guangdong 510642, China
| | - Yongliang Zhang
- Guangdong Province Key Laboratory of Animal Nutritional Regulation, Guangzhou, Guangdong 510642, China.,National Engineering Research Center for Breeding Swine Industry, College of Animal Science, South China Agricultural University, Guangzhou, Guangdong 510642, China
| | - Xiuqi Wang
- National Engineering Research Center for Breeding Swine Industry, College of Animal Science, South China Agricultural University, Guangzhou, Guangdong 510642, China.,South China Observation Experiment Station of Animal Nutrition and Feed Science, Ministry of Agriculture, Guangzhou, Guangdong 510642, China
| | - Qingyan Jiang
- Guangdong Province Key Laboratory of Animal Nutritional Regulation, Guangzhou, Guangdong 510642, China.,South China Observation Experiment Station of Animal Nutrition and Feed Science, Ministry of Agriculture, Guangzhou, Guangdong 510642, China
| | - Gang Shu
- Guangdong Province Key Laboratory of Animal Nutritional Regulation, Guangzhou, Guangdong 510642, China.,National Engineering Research Center for Breeding Swine Industry, College of Animal Science, South China Agricultural University, Guangzhou, Guangdong 510642, China.,South China Observation Experiment Station of Animal Nutrition and Feed Science, Ministry of Agriculture, Guangzhou, Guangdong 510642, China
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11
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Alcaino C, Farrugia G, Beyder A. Mechanosensitive Piezo Channels in the Gastrointestinal Tract. CURRENT TOPICS IN MEMBRANES 2017; 79:219-244. [PMID: 28728818 PMCID: PMC5606247 DOI: 10.1016/bs.ctm.2016.11.003] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Sensation of mechanical forces is critical for normal function of the gastrointestinal (GI) tract and abnormalities in mechanosensation are linked to GI pathologies. In the GI tract there are several mechanosensitive cell types-epithelial enterochromaffin cells, intrinsic and extrinsic enteric neurons, smooth muscle cells and interstitial cells of Cajal. These cells use mechanosensitive ion channels that respond to mechanical forces by altering transmembrane ionic currents in a process called mechanoelectrical coupling. Several mechanosensitive ionic conductances have been identified in the mechanosensory GI cells, ranging from mechanosensitive voltage-gated sodium and calcium channels to the mechanogated ion channels, such as the two-pore domain potassium channels K2P (TREK-1) and nonselective cation channels from the transient receptor potential family. The recently discovered Piezo channels are increasingly recognized as significant contributors to cellular mechanosensitivity. Piezo1 and Piezo2 are nonselective cationic ion channels that are directly activated by mechanical forces and have well-defined biophysical and pharmacologic properties. The role of Piezo channels in the GI epithelium is currently under investigation and their role in the smooth muscle syncytium and enteric neurons is still not known. In this review, we outline the current state of knowledge on mechanosensitive ion channels in the GI tract, with a focus on the known and potential functions of the Piezo channels.
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Affiliation(s)
- C Alcaino
- Mayo Clinic College of Medicine, Rochester, MN, United States
| | - G Farrugia
- Mayo Clinic College of Medicine, Rochester, MN, United States
| | - A Beyder
- Mayo Clinic College of Medicine, Rochester, MN, United States
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12
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Sasmal DK, Yadav R, Lu HP. Single-Molecule Patch-Clamp FRET Anisotropy Microscopy Studies of NMDA Receptor Ion Channel Activation and Deactivation under Agonist Ligand Binding in Living Cells. J Am Chem Soc 2016; 138:8789-801. [DOI: 10.1021/jacs.6b03496] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Dibyendu Kumar Sasmal
- Center for Photochemical
Sciences, Department of Chemistry, Bowling Green State University, Bowling
Green, Ohio 43403, United States
| | - Rajeev Yadav
- Center for Photochemical
Sciences, Department of Chemistry, Bowling Green State University, Bowling
Green, Ohio 43403, United States
| | - H. Peter Lu
- Center for Photochemical
Sciences, Department of Chemistry, Bowling Green State University, Bowling
Green, Ohio 43403, United States
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13
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Zheng J, Zhai K, Chen Y, Zhang X, Miao L, Wei B, Ji G. Nitric oxide mediates stretch-induced Ca2+ oscillation in smooth muscle. J Cell Sci 2016; 129:2430-7. [DOI: 10.1242/jcs.180638] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Accepted: 03/23/2016] [Indexed: 11/20/2022] Open
Abstract
The stretching of smooth muscle tissue modulates contraction via augmentation of Ca2+ transients, but the mechanism underlying stretch-induced Ca2+ transients is still unknown. We found that mechanical stretching and maintenance of mouse urinary bladder smooth muscle strips and single myocytes at the initial length of 30% and 18%, respectively, resulted in Ca2+ oscillations. Experiments indicated that mechanical stretching remarkably increases the production of nitric oxide (NO) as well as the amplitude and duration of muscle contraction. Stretch-induced Ca2+ oscillations and contractility increases were completely abolished by NO inhibitor L-NAME or eNOS gene inactivation. Moreover, exposure of eNOS knockout myocytes to exogenous NO donor induced Ca2+ oscillations. The stretch-induced Ca2+ oscillations were greatly inhibited by selective IP3R inhibitor xestospongin C and partially inhibited by ryanodine. Moreover, the stretch-induced Ca2+ oscillations were also suppressed by LY294002, but not by the soluble guanylyl cyclase (sGC) inhibitor ODQ. These results suggest that myocytes stretching and maintenance at a certain length resulted in Ca2+ oscillations that is NO dependent and sGC/cGMP independent and results from the activation of PI(3)K in smooth muscle.
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Affiliation(s)
- Ji Zheng
- Urological Surgery Research Institute, Southwest Hospital, Third Military Medical University, Gao Tanyan Rd. 30, Chongqing 400038, China
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Rd, Beijing 100101, China
| | - Kui Zhai
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Rd, Beijing 100101, China
| | - Yingxiao Chen
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Rd, Beijing 100101, China
| | - Xu Zhang
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Rd, Beijing 100101, China
| | - Lin Miao
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Rd, Beijing 100101, China
| | - Bin Wei
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI 48201, United States
| | - Guangju Ji
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Rd, Beijing 100101, China
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14
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Huang S, Romero-Ruiz M, Castell OK, Bayley H, Wallace MI. High-throughput optical sensing of nucleic acids in a nanopore array. NATURE NANOTECHNOLOGY 2015; 10:986-91. [PMID: 26322943 PMCID: PMC4821573 DOI: 10.1038/nnano.2015.189] [Citation(s) in RCA: 113] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Accepted: 07/22/2015] [Indexed: 05/24/2023]
Abstract
Protein nanopores such as α-haemolysin and Mycobacterium smegmatis porin A (MspA) can be used to sequence long strands of DNA at low cost. To provide high-speed sequencing, large arrays of nanopores are required, but current nanopore sequencing methods rely on ionic current measurements from individually addressed pores and such methods are likely to prove difficult to scale up. Here we show that, by optically encoding the ionic flux through protein nanopores, the discrimination of nucleic acid sequences and the detection of sequence-specific nucleic acid hybridization events can be parallelized. We make optical recordings at a density of ∼10(4) nanopores per mm(2) in a single droplet interface bilayer. Nanopore blockades can discriminate between DNAs with sub-picoampere equivalent resolution, and specific miRNA sequences can be identified by differences in unzipping kinetics. By creating an array of 2,500 bilayers with a micropatterned hydrogel chip, we are also able to load different samples into specific bilayers suitable for high-throughput nanopore recording.
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Affiliation(s)
- Shuo Huang
- Department of Chemistry, University of Oxford, Oxford OX1 3TA, UK
| | | | - Oliver K. Castell
- Department of Chemistry, University of Oxford, Oxford OX1 3TA, UK
- School of Pharmacy and Pharmaceutical Sciences, College of Biomedical and Life Sciences, Cardiff University, Cardiff, CF10 3NB, UK
| | - Hagan Bayley
- Department of Chemistry, University of Oxford, Oxford OX1 3TA, UK
| | - Mark I. Wallace
- Department of Chemistry, University of Oxford, Oxford OX1 3TA, UK
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15
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Kurth F, Franco-Obregón A, Casarosa M, Küster SK, Wuertz-Kozak K, Dittrich PS. Transient receptor potential vanilloid 2-mediated shear-stress responses in C2C12 myoblasts are regulated by serum and extracellular matrix. FASEB J 2015. [PMID: 26207028 DOI: 10.1096/fj.15-275396] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The developmental sensitivity of skeletal muscle to mechanical forces is unparalleled in other tissues. Calcium entry via reputedly mechanosensitive transient receptor potential (TRP) channel classes has been shown to play an essential role in both the early proliferative stage and subsequent differentiation of skeletal muscle myoblasts, particularly TRP canonical (TRPC) 1 and TRP vanilloid (TRPV) 2. Here we show that C2C12 murine myoblasts respond to fluid flow-induced shear stress with increments in cytosolic calcium that are largely initiated by the mechanosensitive opening of TRPV2 channels. Response to fluid flow was augmented by growth in low extracellular serum concentration (5 vs. 20% fetal bovine serum) by greater than 9-fold and at 18 h in culture, coincident with the greatest TRPV2 channel expression under identical conditions (P < 0.02). Fluid flow responses were also enhanced by substrate functionalization with laminin, rather than with fibronectin, agreeing with previous findings that the gating of TRPV2 is facilitated by laminin. Fluid flow-induced calcium increments were blocked by ruthenium red (27%) and SKF-96365 (38%), whereas they were unaltered by 2-aminoethoxydiphenyl borate, further corroborating that TRPV2 channels play a predominant role in fluid flow mechanosensitivity over that of TRPC1 and TRP melastatin (TRPM) 7.
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Affiliation(s)
- Felix Kurth
- *Department of Biosystems and Science Engineering and Institute for Biomechanics, Eidgenössische Technische Hochschule Zürich, Switzerland; Department of Surgery, Yong Loo Lin School of Medicine, and Department of Physiology, National University of Singapore, Singapore; and National University Hospital Sports Centre, Singapore
| | - Alfredo Franco-Obregón
- *Department of Biosystems and Science Engineering and Institute for Biomechanics, Eidgenössische Technische Hochschule Zürich, Switzerland; Department of Surgery, Yong Loo Lin School of Medicine, and Department of Physiology, National University of Singapore, Singapore; and National University Hospital Sports Centre, Singapore
| | - Marco Casarosa
- *Department of Biosystems and Science Engineering and Institute for Biomechanics, Eidgenössische Technische Hochschule Zürich, Switzerland; Department of Surgery, Yong Loo Lin School of Medicine, and Department of Physiology, National University of Singapore, Singapore; and National University Hospital Sports Centre, Singapore
| | - Simon K Küster
- *Department of Biosystems and Science Engineering and Institute for Biomechanics, Eidgenössische Technische Hochschule Zürich, Switzerland; Department of Surgery, Yong Loo Lin School of Medicine, and Department of Physiology, National University of Singapore, Singapore; and National University Hospital Sports Centre, Singapore
| | - Karin Wuertz-Kozak
- *Department of Biosystems and Science Engineering and Institute for Biomechanics, Eidgenössische Technische Hochschule Zürich, Switzerland; Department of Surgery, Yong Loo Lin School of Medicine, and Department of Physiology, National University of Singapore, Singapore; and National University Hospital Sports Centre, Singapore
| | - Petra S Dittrich
- *Department of Biosystems and Science Engineering and Institute for Biomechanics, Eidgenössische Technische Hochschule Zürich, Switzerland; Department of Surgery, Yong Loo Lin School of Medicine, and Department of Physiology, National University of Singapore, Singapore; and National University Hospital Sports Centre, Singapore
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16
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Mercado J, Baylie R, Navedo MF, Yuan C, Scott JD, Nelson MT, Brayden JE, Santana LF. Local control of TRPV4 channels by AKAP150-targeted PKC in arterial smooth muscle. ACTA ACUST UNITED AC 2014; 143:559-75. [PMID: 24778429 PMCID: PMC4003184 DOI: 10.1085/jgp.201311050] [Citation(s) in RCA: 83] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Angiotensin signaling promotes interactions between AKAP150, PKC, and TRPV4 channels to form signaling domains that control Ca2+ influx into arterial myocytes. Transient receptor potential vanilloid 4 (TRPV4) channels are Ca2+-permeable, nonselective cation channels expressed in multiple tissues, including smooth muscle. Although TRPV4 channels play a key role in regulating vascular tone, the mechanisms controlling Ca2+ influx through these channels in arterial myocytes are poorly understood. Here, we tested the hypothesis that in arterial myocytes the anchoring protein AKAP150 and protein kinase C (PKC) play a critical role in the regulation of TRPV4 channels during angiotensin II (AngII) signaling. Super-resolution imaging revealed that TRPV4 channels are gathered into puncta of variable sizes along the sarcolemma of arterial myocytes. Recordings of Ca2+ entry via single TRPV4 channels (“TRPV4 sparklets”) suggested that basal TRPV4 sparklet activity was low. However, Ca2+ entry during elementary TRPV4 sparklets was ∼100-fold greater than that during L-type CaV1.2 channel sparklets. Application of the TRPV4 channel agonist GSK1016790A or the vasoconstrictor AngII increased the activity of TRPV4 sparklets in specific regions of the cells. PKC and AKAP150 were required for AngII-induced increases in TRPV4 sparklet activity. AKAP150 and TRPV4 channel interactions were dynamic; activation of AngII signaling increased the proximity of AKAP150 and TRPV4 puncta in arterial myocytes. Furthermore, local stimulation of diacylglycerol and PKC signaling by laser activation of a light-sensitive Gq-coupled receptor (opto-α1AR) resulted in TRPV4-mediated Ca2+ influx. We propose that AKAP150, PKC, and TRPV4 channels form dynamic subcellular signaling domains that control Ca2+ influx into arterial myocytes.
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Affiliation(s)
- Jose Mercado
- Department of Physiology & Biophysics and 2 Howard Hughes Medical Institute, Department of Pharmacology, University of Washington, Seattle, WA 98195
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17
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Sasmal D, Lu HP. Single-molecule patch-clamp FRET microscopy studies of NMDA receptor ion channel dynamics in living cells: revealing the multiple conformational states associated with a channel at its electrical off state. J Am Chem Soc 2014; 136:12998-3005. [PMID: 25148304 PMCID: PMC4183623 DOI: 10.1021/ja506231j] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2014] [Indexed: 01/10/2023]
Abstract
Conformational dynamics plays a critical role in the activation, deactivation, and open-close activities of ion channels in living cells. Such conformational dynamics is often inhomogeneous and extremely difficult to be directly characterized by ensemble-averaged spectroscopic imaging or only by single channel patch-clamp electric recording methods. We have developed a new and combined technical approach, single-molecule patch-clamp FRET microscopy, to probe ion channel conformational dynamics in living cell by simultaneous and correlated measurements of real-time single-molecule FRET spectroscopic imaging with single-channel electric current recording. Our approach is particularly capable of resolving ion channel conformational change rate process when the channel is at its electrically off states and before the ion channel is activated, the so-called "silent time" when the electric current signals are at zero or background. We have probed NMDA (N-methyl-D-aspartate) receptor ion channel in live HEK-293 cell, especially, the single ion channel open-close activity and its associated protein conformational changes simultaneously. Furthermore, we have revealed that the seemingly identical electrically off states are associated with multiple conformational states. On the basis of our experimental results, we have proposed a multistate clamshell model to interpret the NMDA receptor open-close dynamics.
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Affiliation(s)
- Dibyendu
Kumar Sasmal
- Department
of Chemistry and
Center for Photochemical Sciences, Bowling
Green State University, Bowling
Green, Ohio 43403, United States
| | - H. Peter Lu
- Department
of Chemistry and
Center for Photochemical Sciences, Bowling
Green State University, Bowling
Green, Ohio 43403, United States
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18
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Joerk A, Seidel RA, Walter SG, Wiegand A, Kahnes M, Klopfleisch M, Kirmse K, Pohnert G, Westerhausen M, Witte OW, Holthoff K. Impact of heme and heme degradation products on vascular diameter in mouse visual cortex. J Am Heart Assoc 2014; 3:jah3660. [PMID: 25169792 PMCID: PMC4310418 DOI: 10.1161/jaha.114.001220] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
BACKGROUND Delayed cerebral vasospasm is the most common cause of mortality and severe neurological impairment in patients who survive subarachnoid hemorrhage. Despite improvements in the field of diagnostic imaging, options for prevention and medical treatment-primarily with the calcium channel antagonist nimodipine or hemodynamic manipulations-are insufficient. Previous studies have suggested that heme and bilirubin oxidation end products, originating from degraded hemoglobin around ruptured blood vessels, are involved in the development of vasospasm by inhibiting large conductance BKC a potassium channels in vascular smooth muscle cells. In this study, we identify individual heme degradation products regulating arteriolar diameter in dependence of BKC a channel activity. METHODS AND RESULTS Using differential interference contrast video microscopy in acute brain slices, we determined diameter changes of intracerebral arterioles in mouse visual cortex. In preconstricted vessels, the specific BKC a channel blockers paxilline and iberiotoxin as well as iron-containing hemin caused vasoconstriction. In addition, the bilirubin oxidation end product Z-BOX A showed a stronger vasoconstrictive potency than its regio-isomer Z-BOX B. Importantly, Z-BOX A had the same vasoconstrictive effect, independent of its origin from oxidative degradation or chemical synthesis. Finally, in slices of Slo1-deficient knockout mice, paxilline and Z-BOX A remained ineffective in changing arteriole diameter. CONCLUSIONS We identified individual components of the oxidative bilirubin degradation that led to vasoconstriction of cerebral arterioles. The vasoconstrictive effect of Z-BOX A and Z-BOX B was mediated by BKC a channel activity that might represent a signaling pathway in the occurrence of delayed cerebral vasospasm in subarachnoid hemorrhage patients.
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Affiliation(s)
- Alexander Joerk
- Hans‐Berger Department of Neurology, University Hospital Jena, Germany (A.J., S.G.W., A.W., K.K., O.W.W., K.H.)
| | - Raphael Andreas Seidel
- Institute of Inorganic and Analytical Chemistry, Friedrich‐Schiller University, Jena, Germany (R.A.S., M.K., M.K., G.P., M.W.)
- Department of Anesthesiology and Intensive Care Medicine/Center for Sepsis Control and Care, University Hospital, Friedrich Schiller University, Jena, Germany (R.A.S.)
| | - Sebastian Gottfried Walter
- Hans‐Berger Department of Neurology, University Hospital Jena, Germany (A.J., S.G.W., A.W., K.K., O.W.W., K.H.)
| | - Anne Wiegand
- Hans‐Berger Department of Neurology, University Hospital Jena, Germany (A.J., S.G.W., A.W., K.K., O.W.W., K.H.)
| | - Marcel Kahnes
- Institute of Inorganic and Analytical Chemistry, Friedrich‐Schiller University, Jena, Germany (R.A.S., M.K., M.K., G.P., M.W.)
| | - Maurice Klopfleisch
- Institute of Inorganic and Analytical Chemistry, Friedrich‐Schiller University, Jena, Germany (R.A.S., M.K., M.K., G.P., M.W.)
| | - Knut Kirmse
- Hans‐Berger Department of Neurology, University Hospital Jena, Germany (A.J., S.G.W., A.W., K.K., O.W.W., K.H.)
| | - Georg Pohnert
- Institute of Inorganic and Analytical Chemistry, Friedrich‐Schiller University, Jena, Germany (R.A.S., M.K., M.K., G.P., M.W.)
| | - Matthias Westerhausen
- Institute of Inorganic and Analytical Chemistry, Friedrich‐Schiller University, Jena, Germany (R.A.S., M.K., M.K., G.P., M.W.)
| | - Otto Wilhelm Witte
- Hans‐Berger Department of Neurology, University Hospital Jena, Germany (A.J., S.G.W., A.W., K.K., O.W.W., K.H.)
| | - Knut Holthoff
- Hans‐Berger Department of Neurology, University Hospital Jena, Germany (A.J., S.G.W., A.W., K.K., O.W.W., K.H.)
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19
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Lopez-Ayon GM, Liu HY, Xing S, Maria OM, LeDue JM, Bourque H, Grutter P, Komarova SV. Local membrane deformation and micro-injury lead to qualitatively different responses in osteoblasts. F1000Res 2014; 3:162. [PMID: 25254108 PMCID: PMC4168753 DOI: 10.12688/f1000research.4448.1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 07/11/2014] [Indexed: 11/24/2022] Open
Abstract
Micro-damage of bone tissue is known to regulate bone turnover. However, it is unknown if individual bone cells can differentiate between membrane deformation and micro-injury. We generated osteoblasts from mouse bone marrow or bone morphogenetic protein 2-transfected C2C12 cells. Single cells were mechanically stimulated by indentation with the atomic force microscopy probe with variable force load either resulting in membrane deformation only, or leading to membrane penetration and micro-injury. Changes in the cytosolic free calcium concentration ([Ca (2+)] i) in fluo4-AM loaded cells were analyzed. When deformation only was induced, it resulted in an immediate elevation of [Ca (2+)] i which was localized to the probe periphery. Multiple consecutive local Ca (2+) responses were induced by sequential application of low level forces, with characteristic recovery time of ~2 s. The duration of [Ca (2+)] i elevations was directly proportional to the tip-cell contact time. In contrast, cell micro-injury resulted in transient global elevations of [Ca (2+)] i, the magnitude of which was independent of the tip-cell contact time. Sequential micro-injury of the same cell did not induce Ca (2+) response within 30 s of the first stimulation. Both local and global Ca (2+)elevations were blocked in Ca (2+)-free media or in the presence of stretch-activated channel blocker Gd (3+). In addition, amount of Ca (2+) released during global responses was significantly reduced in the presence of PLC inhibitor Et-18-OCH 3. Thus, we found qualitative differences in calcium responses to mechanical forces inducing only membrane deformation or deformation leading to micro-injury.
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Affiliation(s)
- G Monserratt Lopez-Ayon
- Center for the Physics of Materials and the Department of Physics, McGill University, 3600 University, Montreal, Quebec, H3A 2T8, Canada
| | - Heng-Yen Liu
- Faculty of Dentistry, McGill University, 3640 University, Montreal, Quebec, H3A 0C7, Canada ; Shriners Hospital for Children - Canada, 1529 Cedar Ave, Montreal, Quebec, H3G IA6, Canada
| | - Shu Xing
- Center for the Physics of Materials and the Department of Physics, McGill University, 3600 University, Montreal, Quebec, H3A 2T8, Canada ; Faculty of Dentistry, McGill University, 3640 University, Montreal, Quebec, H3A 0C7, Canada
| | - Osama M Maria
- Faculty of Dentistry, McGill University, 3640 University, Montreal, Quebec, H3A 0C7, Canada
| | - Jeffrey M LeDue
- Center for the Physics of Materials and the Department of Physics, McGill University, 3600 University, Montreal, Quebec, H3A 2T8, Canada
| | - Helene Bourque
- Center for the Physics of Materials and the Department of Physics, McGill University, 3600 University, Montreal, Quebec, H3A 2T8, Canada
| | - Peter Grutter
- Center for the Physics of Materials and the Department of Physics, McGill University, 3600 University, Montreal, Quebec, H3A 2T8, Canada
| | - Svetlana V Komarova
- Faculty of Dentistry, McGill University, 3640 University, Montreal, Quebec, H3A 0C7, Canada ; Shriners Hospital for Children - Canada, 1529 Cedar Ave, Montreal, Quebec, H3G IA6, Canada
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20
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Gilbert G, Ducret T, Marthan R, Savineau JP, Quignard JF. Stretch-induced Ca2+ signalling in vascular smooth muscle cells depends on Ca2+ store segregation. Cardiovasc Res 2014; 103:313-23. [PMID: 24692174 DOI: 10.1093/cvr/cvu069] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
AIM Calcium is a key second messenger that can be mobilized from both the extracellular medium and intracellular calcium stores. Pulmonary arterial smooth muscle cells (PASMCs) respond to stretch by a calcium increase, a mechanism enhanced during pulmonary hypertension (PH). We investigated the role of the spatial organization between plasma membrane stretch-activated channels (SACs) and intracellular calcium stores [sarcoplasmic reticulum (SR), mitochondria, and lysosomes) in response to stretch. METHODS AND RESULTS Studies were performed in freshly isolated PASMCs from both control and two different rat models of PH (chronically hypoxic and monocrotaline-treated rats). Co-immunolabellings revealed that the subcellular segregation between each subtype of SR ryanodine receptors (RyR1, RyR2, and RyR3), SERCA2 pumps (SERCA2a and SERCA2b), mitochondria, or lysosomes in freshly isolated PASMCs differs from control and PH PASMCs. In control PASMCs, stretching the membrane activates a Ca(2+) influx through SACs. This influx is amplified by cell hyperpolarization, a calcium release by subplasmalemmal RyR1 and is then buffered by mitochondria. In two different PH rat models, the calcium response to stretch is enhanced due to hyper-reactivity of SACs and a greater calcium amplification by all RyR subtypes. CONCLUSION The spatial organization of RyR and calcium stores in PASMCs is important for cell signalling and plays a causal role in PH.
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Affiliation(s)
- Guillaume Gilbert
- Centre de Recherche Cardio-Thoracique de Bordeaux, Universite de Bordeaux, Bordeaux F-33000, France Centre de Recherche Cardio-Thoracique de Bordeaux, INSERM, U 1045, Bordeaux F-33000, France
| | - Thomas Ducret
- Centre de Recherche Cardio-Thoracique de Bordeaux, Universite de Bordeaux, Bordeaux F-33000, France Centre de Recherche Cardio-Thoracique de Bordeaux, INSERM, U 1045, Bordeaux F-33000, France
| | - Roger Marthan
- Centre de Recherche Cardio-Thoracique de Bordeaux, Universite de Bordeaux, Bordeaux F-33000, France Centre de Recherche Cardio-Thoracique de Bordeaux, INSERM, U 1045, Bordeaux F-33000, France CHU Bordeaux, Exploration Fonctionnelle Respiratoire, Bordeaux F-33000, France
| | - Jean-Pierre Savineau
- Centre de Recherche Cardio-Thoracique de Bordeaux, Universite de Bordeaux, Bordeaux F-33000, France Centre de Recherche Cardio-Thoracique de Bordeaux, INSERM, U 1045, Bordeaux F-33000, France
| | - Jean-François Quignard
- Centre de Recherche Cardio-Thoracique de Bordeaux, Universite de Bordeaux, Bordeaux F-33000, France Centre de Recherche Cardio-Thoracique de Bordeaux, INSERM, U 1045, Bordeaux F-33000, France Centre de Recherche Cardio-Thoracique de Bordeaux, 146 rue Léo Saignat, Bat TP - 2ème étage, 33076 Bordeaux Cedex, France
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21
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Navedo MF, Amberg GC. Local regulation of L-type Ca²⁺ channel sparklets in arterial smooth muscle. Microcirculation 2013; 20:290-8. [PMID: 23116449 DOI: 10.1111/micc.12021] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2012] [Accepted: 10/26/2012] [Indexed: 12/16/2022]
Abstract
This review addresses the latest advances in our understanding of the regulation of a novel Ca²⁺ signal called L-type Ca²⁺ channel sparklets in arterial smooth muscle. L-type Ca²⁺ channel sparklets are elementary Ca²⁺ influx events produced by the opening of a single or a small cluster of L-type Ca²⁺ channels. These Ca²⁺ signals were first visualized in the vasculature in arterial smooth muscle cells. In these cells, L-type Ca²⁺ channel sparklets display two functionally distinct gating modalities that regulate local and global [Ca²⁺](i). The activity of L-type Ca²⁺ channel sparklets varies regionally within a cell depending on the dynamic activity of a cohort of protein kinases and phosphatases recruited to L-type Ca²⁺ channels in the arterial smooth muscle sarcolemma in a complex coordinated by the scaffolding molecule AKAP150. We also described a mechanism whereby clusters of L-type Ca²⁺ channels gate cooperatively to amplify intracellular Ca²⁺ signals with likely pathological consequences.
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Affiliation(s)
- Manuel F Navedo
- Department of Pharmacology, University of California, Davis, California, USA.
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22
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Torres-Narváez JC, Mondragón LDV, Varela López E, Pérez-Torres I, Díaz Juárez JA, Suárez J, Hernández GP. Role of the transient receptor potential vanilloid type 1 receptor and stretch-activated ion channels in nitric oxide release from endothelial cells of the aorta and heart in rats. Exp Clin Cardiol 2012; 17:89-94. [PMID: 23620694 PMCID: PMC3628419] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Shear stress stimulates nitric oxide (NO) release in endothelial cells. Stretch-activated ion channels (SACs) and the transient receptor potential vanilloid type 1 (TRPV1) receptor respond to mechanical stimulus and are permeable to Na(+), Ca(2+) and K(+). The influence of SACs and the TRPV1 receptor on NO release on the heart and on the vascular reactivity of the thoracic aorta (TA) was studied. Experiments were performed in isolated perfused heart, cultured endothelial cells and TA rings from Wistar rats. Capsaicin (10 μM, 30 μM) was used as a NO release stimulator, capsazepine (6 μM, 10 μM) was used as a capsaicin antagonist and gadolinium (3 μM, 5 μM) was used as an inhibitor of SACs. NO was measured by the Kelm and Tenorio methods. Left ventricular pressure was recorded and coronary vascular resistance was calculated. Capsaicin increased NO release in the heart by 58% (395±8 pmol/mL to 627±23 pmol/mL). Capsazepine and gadolinium inhibited NO release by 74% and 82%, respectively. This tendency was similar in all experimental models. Capsaicin attenuated the effects of norepinephrine (10 M to 7 M) on TA and had no effect in the presence of N (ω)-nitro-L-arginine methyl ester. Therefore, the authors conclude that SACs and the TRPV1 receptor are both present in the coronary endothelium and that both participate in Ca(2+)-dependent NO release.
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Affiliation(s)
| | | | | | - Israel Pérez-Torres
- Departamento de Patología, Instituto Nacional de Cardiología “Ignacio Chávez”, México D F, México
| | | | - Jorge Suárez
- Department of Medicine, University of California, San Diego, La Jolla, California, USA
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23
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Huang H, Wang W, Liu P, Jiang Y, Zhao Y, Wei H, Niu W. TRPC1 expression and distribution in rat hearts. Eur J Histochem 2012; 53:e26. [PMID: 22073358 PMCID: PMC3167335 DOI: 10.4081/ejh.2009.e26] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/09/2009] [Indexed: 12/31/2022] Open
Abstract
Transient receptor potential canonical (TRPC) proteins have been identified as a family of plasma membrane calcium-permeable channels. TRPC proteins can be activated by various stimuli and act as cellular sensors in mammals. Stretch-activated ion channels (SACs) have been proposed to underlie cardiac mechano-electric feedback (MEF), although the molecular entity of SAC remains unknown. There is evidence suggesting that transient receptor potential canonical 1 (TRPC1) is a stretch-activated ion channel. As a non-selective cation channel, TRPC1 may cause stretch-induced depolarization and arrhythmia and thus may contribute to the MEF of the heart. In this study, we examined the expression patterns of TRPC1 in detail at both the mRNA and protein levels in rat hearts. We isolated total RNA from the left and right atria, and the left and right ventricles, and detected TRPC1 mRNA in these tissues using reverse-transcriptase polymerase chain reaction (RT-PCR). To study the protein localization and targeting, we performed immunohistochemistry and immunofluorescence labeling with the antibody against TRPC1. TRPC1 was detected in the cardiomyocytes of the ventricle and atrium at both the mRNA and protein levels. The cell membrane and T-tubule showed strong fluorescence labeling in the ventricular myocytes. Purkinje cells, the endothelial cells and smooth muscle cells of the coronary arterioles also displayed TRPC1 labeling. No TRPC1 was detected in fibroblasts. In conclusion, TRPC1 is widely expressed in the rat heart, including in working cells, Purkinje cells and vascular cells, suggesting that it plays an important role in the heart. The specific distribution pattern offered a useful insight into its function in adult rat ventricular cells. Further investigations are needed to clarify the role of TRPC1 in regulating cardiac activity, including cardiac MEF.
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Affiliation(s)
- H Huang
- Department of Physiology, Capital Medical University, Beijing, China
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24
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Li X, Li PCH. Strategies for the real-time detection of Ca2+ channel events of single cells: recent advances and new possibilities. Expert Rev Clin Pharmacol 2012; 3:267-80. [PMID: 22111609 DOI: 10.1586/ecp.10.16] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Ca(2+) ion channels play key roles in cell physiology and they are important drug targets. The Ca(2+) channel events are mainly measurable by fluorescent and patch clamp methods. This review summarizes the recent advances of these techniques for the detection of Ca(2+) channel events and the prospect of their new directions in the near future. Conventional bulk fluorescent methods are amenable to high-throughput applications, but they are not real-time single-cell measurements, which provide kinetic data on individual cells and offer unparalleled sensitive data for rare cells. Recent advances on real-time single-cell fluorescent measurements are conducted on microfluidic chips with scalable cell-retention sites, integrated with electrical stimulation and fluorescent measuring features. Patch clamp techniques are real-time measurements conducted on single cells, but the measurements are of low throughput. Recent advances are conducted on microfluidic patch clamp chips for high-throughput applications. Future real-time single-cell Ca(2+) channel event measurements will be conducted in a multiparametric manner in an integrated and automated microfluidic chip.
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Affiliation(s)
- XiuJun Li
- University of California at Berkeley, CA 94720, USA
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25
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Gross LCM, Castell OK, Wallace MI. Dynamic and reversible control of 2D membrane protein concentration in a droplet interface bilayer. NANO LETTERS 2011; 11:3324-3328. [PMID: 21726072 DOI: 10.1021/nl201689v] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We form an artificial lipid bilayer between a nanolitre aqueous droplet and a supporting hydrogel immersed in an oil/lipid solution. Manipulation of the axial position of the droplet relative to the hydrogel controls the size of the bilayer formed at the interface; this enables the surface density of integral membrane proteins to be controlled. We are able to modulate the surface density of the β-barrel pore-forming toxin α-hemolysin over a range of 4 orders of magnitude within a time frame of a few seconds. The concentration changes are fully reversible. Membrane protein function and diffusion are unaltered, as measured by single molecule microscopy and single channel electrical recording.
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Affiliation(s)
- Linda C M Gross
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, OX1 3TA, Oxford, U.K
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26
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Lifshitz LM, Carmichael JD, Lai FA, Sorrentino V, Bellvé K, Fogarty KE, ZhuGe R. Spatial organization of RYRs and BK channels underlying the activation of STOCs by Ca(2+) sparks in airway myocytes. ACTA ACUST UNITED AC 2011; 138:195-209. [PMID: 21746845 PMCID: PMC3149436 DOI: 10.1085/jgp.201110626] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Short-lived, localized Ca2+ events mediate Ca2+ signaling with high efficiency and great fidelity largely as a result of the close proximity between Ca2+-permeable ion channels and their molecular targets. However, in most cases, direct evidence of the spatial relationship between these two types of molecules is lacking, and, thus, mechanistic understanding of local Ca2+ signaling is incomplete. In this study, we use an integrated approach to tackling this issue on a prototypical local Ca2+ signaling system composed of Ca2+ sparks resulting from the opening of ryanodine receptors (RYRs) and spontaneous transient outward currents (STOCs) caused by the opening of Ca2+-activated K+ (BK) channels in airway smooth muscle. Biophysical analyses of STOCs and Ca2+ sparks acquired at 333 Hz demonstrate that these two events are associated closely in time, and approximately eight RYRs open to give rise to a Ca2+ spark, which activates ∼15 BK channels to generate a STOC at 0 mV. Dual immunocytochemistry and 3-D deconvolution at high spatial resolution reveal that both RYRs and BK channels form clusters and RYR1 and RYR2 (but not RYR3) localize near the membrane. Using the spatial relationship between RYRs and BK channels, the spatial-temporal profile of [Ca2+] resulting from Ca2+ sparks, and the kinetic model of BK channels, we estimate that an average Ca2+ spark caused by the opening of a cluster of RYR1 or RYR2 acts on BK channels from two to three clusters that are randomly distributed within an ∼600-nm radius of RYRs. With this spatial organization of RYRs and BK channels, we are able to model BK channel currents with the same salient features as those observed in STOCs across a range of physiological membrane potentials. Thus, this study provides a mechanistic understanding of the activation of STOCs by Ca2+ sparks using explicit knowledge of the spatial relationship between RYRs (the Ca2+ source) and BK channels (the Ca2+ target).
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Affiliation(s)
- Lawrence M Lifshitz
- Biomedical Imaging Group, University of Massachusetts Medical School, Worcester, MA 01605, USA
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27
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Ribrault C, Sekimoto K, Triller A. From the stochasticity of molecular processes to the variability of synaptic transmission. Nat Rev Neurosci 2011; 12:375-87. [PMID: 21685931 DOI: 10.1038/nrn3025] [Citation(s) in RCA: 119] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The variability of the postsynaptic response following a single action potential arises from two sources: the neurotransmitter release is probabilistic, and the postsynaptic response to neurotransmitter release has variable timing and amplitude. At individual synapses, the number of molecules of a given type that are involved in these processes is small enough that the stochastic (random) properties of molecular events cannot be neglected. How the stochasticity of molecular processes contributes to the variability of synaptic transmission, its sensitivity and its robustness to molecular fluctuations has important implications for our understanding of the mechanistic basis of synaptic transmission and of synaptic plasticity.
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Affiliation(s)
- Claire Ribrault
- Laboratoire Matières et Systèmes Complexes, CNRS-UMR7057, Université Paris 7, F-75205 Paris cedex 13, France
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28
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Shklyar TF, Safronov AP, Toropova OA, Pollack GH, Blyakhman FA. Mechanoelectric potentials in synthetic hydrogels: Possible relation to cytoskeleton. Biophysics (Nagoya-shi) 2011. [DOI: 10.1134/s0006350910060084] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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29
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Santana LF, Navedo MF. Natural inequalities: why some L-type Ca2+ channels work harder than others. ACTA ACUST UNITED AC 2010; 136:143-7. [PMID: 20660657 PMCID: PMC2912067 DOI: 10.1085/jgp.200910391] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- Luis F Santana
- Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195, USA.
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30
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Ducret T, El Arrouchi J, Courtois A, Quignard JF, Marthan R, Savineau JP. Stretch-activated channels in pulmonary arterial smooth muscle cells from normoxic and chronically hypoxic rats. Cell Calcium 2010; 48:251-9. [DOI: 10.1016/j.ceca.2010.09.011] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2010] [Revised: 09/10/2010] [Accepted: 09/30/2010] [Indexed: 10/18/2022]
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31
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Raizman I, De Croos JNA, Pilliar R, Kandel RA. Calcium regulates cyclic compression-induced early changes in chondrocytes during in vitro cartilage tissue formation. Cell Calcium 2010; 48:232-42. [PMID: 20932575 DOI: 10.1016/j.ceca.2010.09.006] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2010] [Revised: 09/07/2010] [Accepted: 09/08/2010] [Indexed: 11/18/2022]
Abstract
A single application of cyclic compression (1kPa, 1Hz, 30min) to bioengineered cartilage results in improved tissue formation through sequential catabolic and anabolic changes mediated via cell shape changes that are regulated by α5β1 integrin and membrane-type metalloprotease (MT1-MMP). To determine if calcium was involved in this process, the role of calcium in regulating cell shape changes, MT1-MMP expression and integrin activity in response to mechanical stimulation was examined. Stimulation-induced changes in cell shape and MT1-MMP expression were abolished by chelation of extracellular calcium, and this effect was reversed by re-introduction of calcium. Spreading was inhibited by blocking stretch-activated channels (with gadolinium), while retraction was prevented by blocking the L-Type voltage-gated channel (with nifedipine); both compounds inhibited MT1-MMP upregulation. Calcium A23187 ionophore restored cellular response further supporting a role for these channels. Calcium regulated the integrin-mediated signalling pathway, which was facilitated through Src kinase. Both calcium- and integrin-mediated pathways converged on ERK-MAPK in response to stimulation. While both integrins and calcium signalling mediate chondrocyte mechanotransduction, calcium appears to play the major regulatory role. Understanding the underlying molecular mechanisms involved in chondrocyte mechanotransduction may lead to the development of improved bioengineered cartilage.
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Affiliation(s)
- Igal Raizman
- CIHR-BioEngineering of Skeletal Tissue Team, Mount Sinai Hospital, University of Toronto, Toronto, Ontario, Canada M5G 1X5
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32
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Santana LF, Navedo MF. Molecular and biophysical mechanisms of Ca2+ sparklets in smooth muscle. J Mol Cell Cardiol 2009; 47:436-44. [PMID: 19616004 DOI: 10.1016/j.yjmcc.2009.07.008] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/28/2009] [Revised: 06/17/2009] [Accepted: 07/06/2009] [Indexed: 11/25/2022]
Abstract
In this article, we review the biophysical basis and functional implications of a novel Ca(2+) signal (called "Ca(2+) sparklets") produced by Ca(2+) influx via L-type Ca(2+) channels (LTCCs) in smooth muscle. Ca(2+) sparklet activity is bimodal. In low activity mode, Ca(2+) sparklets are produced by random, brief openings of solitary LTCCs. In contrast, small clusters of LTCCs can function in a high activity mode that creates sites of continual Ca(2+) influx called "persistent Ca(2+) sparklets". Low activity and persistent Ca(2+) sparklets contribute to Ca(2+) influx in arterial, colonic, and venous smooth muscle. Targeting of PKCalpha by the scaffolding protein AKAP150 to specific sarcolemmal domains is required for the activation of persistent Ca(2+) sparklets. Calcineurin, which is also associated with AKAP150, opposes the actions of PKCalpha on Ca(2+) sparklets. At hyperpolarized potentials, Ca(2+) sparklet activity is low and hence does not contribute to global [Ca(2+)](i). Membrane depolarization increases low and persistent Ca(2+) sparklet activity, thereby increasing local and global [Ca(2+)](i). Ca(2+) sparklet activity is increased in arterial myocytes during hypertension, thus increasing Ca(2+) influx and activating the transcription factor NFATc3. We discuss a model for subcellular variations in Ca(2+) sparklet activity and their role in the regulation of excitation-contraction coupling and excitation-transcription coupling in smooth muscle.
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Affiliation(s)
- Luis F Santana
- Department of Physiology and Biophysics, University of Washington, Box 357290, Seattle, WA 98195, USA.
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33
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Lee Y, Park SY, Kim C, Park TG. Thermally triggered intracellular explosion of volume transition nanogels for necrotic cell death. J Control Release 2009; 135:89-95. [DOI: 10.1016/j.jconrel.2008.12.008] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2008] [Revised: 12/09/2008] [Accepted: 12/12/2008] [Indexed: 11/27/2022]
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34
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Heron AJ, Thompson JR, Cronin B, Bayley H, Wallace MI. Simultaneous Measurement of Ionic Current and Fluorescence from Single Protein Pores. J Am Chem Soc 2009; 131:1652-3. [DOI: 10.1021/ja808128s] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Andrew J. Heron
- Department of Chemistry, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, U.K
| | - James R. Thompson
- Department of Chemistry, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, U.K
| | - Bríd Cronin
- Department of Chemistry, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, U.K
| | - Hagan Bayley
- Department of Chemistry, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, U.K
| | - Mark I. Wallace
- Department of Chemistry, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, U.K
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35
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Abstract
In numerous plant signal transduction pathways, Ca2+ is a versatile second messenger which controls the activation of many downstream actions in response to various stimuli. There is strong evidence to indicate that information encoded within these stimulus-induced Ca2+ oscillations can provide signalling specificity. Such Ca2+ signals, or 'Ca2+ signatures', are generated in the cytosol, and in noncytosolic locations including the nucleus and chloroplast, through the coordinated action of Ca2+ influx and efflux pathways. An increased understanding of the functions and regulation of these various Ca2+ transporters has improved our appreciation of the role these transporters play in specifically shaping the Ca2+ signatures. Here we review the evidence which indicates that Ca2+ channel, Ca2+-ATPase and Ca2+ exchanger isoforms can indeed modulate specific Ca2+ signatures in response to an individual signal.
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Affiliation(s)
- Martin R McAinsh
- Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, UK;Faculty of Life Sciences, University of Manchester, Michael Smith Building, Oxford Road, Manchester M13 9PT, UK
| | - Jon K Pittman
- Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, UK;Faculty of Life Sciences, University of Manchester, Michael Smith Building, Oxford Road, Manchester M13 9PT, UK
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36
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Wei C, Wang X, Chen M, Ouyang K, Song LS, Cheng H. Calcium flickers steer cell migration. Nature 2008; 457:901-5. [PMID: 19118385 DOI: 10.1038/nature07577] [Citation(s) in RCA: 458] [Impact Index Per Article: 28.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2008] [Accepted: 10/21/2008] [Indexed: 12/19/2022]
Abstract
Directional movement is a property common to all cell types during development and is critical to tissue remodelling and regeneration after damage. In migrating cells, calcium has a multifunctional role in directional sensing, cytoskeleton redistribution, traction force generation, and relocation of focal adhesions. Here we visualize high-calcium microdomains ('calcium flickers') and their patterned activation in migrating human embryonic lung fibroblasts. Calcium flicker activity is dually coupled to membrane tension (by means of TRPM7, a stretch-activated Ca(2+)-permeant channel of the transient receptor potential superfamily) and chemoattractant signal transduction (by means of type 2 inositol-1,4,5-trisphosphate receptors). Interestingly, calcium flickers are most active at the leading lamella of migrating cells, displaying a 4:1 front-to-rear polarization opposite to the global calcium gradient. When exposed to a platelet-derived growth factor gradient perpendicular to cell movement, asymmetric calcium flicker activity develops across the lamella and promotes the turning of migrating fibroblasts. These findings show how the exquisite spatiotemporal organization of calcium microdomains can orchestrate complex cellular processes such as cell migration.
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Affiliation(s)
- Chaoliang Wei
- Institute of Molecular Medicine, State Key Laboratory of Biomembrane and Membrane Biotechnology, Peking University, Beijing 100871, China.
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37
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Lee S, Lee HG, Kang SH. Real-Time Observations of Intracellular Mg2+ Signaling and Waves in a Single Living Ventricular Myocyte Cell. Anal Chem 2008; 81:538-42. [DOI: 10.1021/ac8013324] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Seungah Lee
- Department of Chemistry and Research Institute of Physics and Chemistry (RINPAC), Chonbuk National University, Jeonju 561-756, South Korea, and Cellomics Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon 305-806, South Korea
| | - Hee Gu Lee
- Department of Chemistry and Research Institute of Physics and Chemistry (RINPAC), Chonbuk National University, Jeonju 561-756, South Korea, and Cellomics Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon 305-806, South Korea
| | - Seong Ho Kang
- Department of Chemistry and Research Institute of Physics and Chemistry (RINPAC), Chonbuk National University, Jeonju 561-756, South Korea, and Cellomics Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon 305-806, South Korea
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38
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Follonier L, Schaub S, Meister JJ, Hinz B. Myofibroblast communication is controlled by intercellular mechanical coupling. J Cell Sci 2008; 121:3305-16. [PMID: 18827018 DOI: 10.1242/jcs.024521] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Neoformation of intercellular adherens junctions accompanies the differentiation of fibroblasts into contractile myofibroblasts, a key event during development of fibrosis and in wound healing. We have previously shown that intercellular mechanical coupling of stress fibres via adherens junctions improves contraction of collagen gels by myofibroblasts. By assessing spontaneous intracellular Ca2+ oscillations, we here test whether adherens junctions mechanically coordinate myofibroblast activities. Periodic Ca2+ oscillations are synchronised between physically contacting myofibroblasts and become desynchronised upon dissociation of adherens junctions with function-blocking peptides. Similar uncoupling is obtained by inhibiting myofibroblast contraction using myosin inhibitors and by blocking mechanosensitive ion channels using Gd3+ and GSMTx4. By contrast, gap junction uncouplers do not affect myofibroblast coordination. We propose the following model of mechanical coupling for myofibroblasts: individual cell contraction is transmitted via adherens junctions and leads to the opening of mechanosensitive ion channels in adjacent cells. The resulting Ca2+ influx induces a contraction that can feed back on the first cell and/or stimulate other contacting cells. This mechanism could improve the remodelling of cell-dense tissue by coordinating the activity of myofibroblasts.
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Affiliation(s)
- Lysianne Follonier
- Laboratory of Cell Biophysics, Ecole Polytechnique Fédérale de Lausanne (EPFL), Bâtiment SG-AA-B143, Station 15, CH-1015 Lausanne, Switzerland
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39
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Guibert C, Ducret T, Savineau JP. Voltage-independent calcium influx in smooth muscle. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2008; 98:10-23. [DOI: 10.1016/j.pbiomolbio.2008.05.001] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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40
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Calcium dynamics and vasomotion in arteries subject to isometric, isobaric, and isotonic conditions. Biophys J 2008; 95:2728-38. [PMID: 18586845 DOI: 10.1529/biophysj.108.131136] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In vitro, different techniques are used to study the smooth muscle cells' calcium dynamics and contraction/relaxation mechanisms on arteries. Most experimental studies use either an isometric or an isobaric setup. However, in vivo, a blood vessel is neither isobaric nor isometric nor isotonic, as it is continuously submitted to intraluminal pressure variations arising from heart beat. We use a theoretical model of the smooth muscle calcium and arterial radius dynamics to determine whether results may be considerably different depending on the experimental conditions (isometric, isobaric, isotonic, or cyclic pressure variations). We show that isobaric conditions appear to be more realistic than isometric or isotonic situations, as the calcium dynamics is similar under cyclic intraluminal pressure variations (in vivo-like situation) and under a constant pressure (isobaric situation). The arterial contraction is less pronounced in isotonic than in isobaric conditions, and the vasoconstrictor sensitivity higher in isometric than isobaric or isotonic conditions, in agreement with experimental observations. Interestingly, the model predicts that isometric conditions may generate artifacts like the coexistence of multiple stable states. We have verified this model prediction experimentally using rat mesenteric arteries mounted on a wire myograph and stimulated with phenylephrine.
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41
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Abstract
Actomyosin-based cortical contractility is a common feature of eukaryotic cells and is involved in cell motility, cell division, and apoptosis. In nonmuscle cells, oscillations in contractility are induced by microtubule depolymerization during cell spreading. We developed an ordinary differential equation model to describe this behavior. The computational model includes 36 parameters. The values for all but two of the model parameters were taken from experimental measurements found in the literature. Using these values, we demonstrate that the model generates oscillatory behavior consistent with current experimental observations. The rhythmic behavior occurs because of the antagonistic effects of calcium-induced contractility and stretch-activated calcium channels. The model makes several experimentally testable predictions: 1), buffering intracellular calcium increases the period and decreases the amplitude of cortical oscillations; 2), increasing the number or activity of stretch activated channels leads to an increase in period and amplitude of cortical oscillations; 3), inhibiting Ca(2+) pump activity increases the period and amplitude of oscillations; and 4), a threshold exists for the calcium concentration below which oscillations cease.
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42
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Comerford L, Bolger NM, Bund SJ. Characteristics of the myogenic behaviour of arteries of the common European frog (Rana temporaria). ACTA PHYSIOLOGICA HUNGARICA 2008; 95:45-53. [PMID: 18389997 DOI: 10.1556/aphysiol.95.2008.1.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Mammalian small arteries exhibit pressure-dependent myogenic behaviour characterised by an active constriction in response to an increased transmural pressure or an active dilatation in response to a decreased transmural pressure. This study aimed to determine whether pressure-dependent myogenic responses are a functional feature of amphibian arteries. Mesenteric and skeletal muscle arteries from the common European frog (Rana temporaria) were cannulated at either end with two fine glass micropipettes in the chamber of an arteriograph. Arterial pressure-diameter relationships (5-40 mmHg) were determined in the presence and absence of Ca2+. All arteries dilated passively with increasing pressure in the absence of Ca2+. In the presence of Ca2+ proximal mesenteric branches and tibial artery branches dilated with increasing transmural pressure but tone (p < 0.05) was evident in both arteries. A clear myogenic response to a step increase or decrease in pressure was observed in small distal arteries (6 of 13 mesenteric and 7 of 10 sciatic branches) resulting in significantly (p < 0.05) narrower diameters in Ca2+ in the range 10-40 mmHg in mesenteric and 20-40 mmHg in sciatic arteries, respectively. The results demonstrate that arteries of an amphibian can generate spontaneous pressure-dependent tone. This is the first study to demonstrate myogenic contractile behaviour in arteries of nonmammalian origin.
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Affiliation(s)
- L Comerford
- UCD School of Medicine and Medical Science, Health Sciences Centre, University College Dublin, Belfield, Dublin 4, Ireland
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43
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Hayakawa K, Tatsumi H, Sokabe M. Actin stress fibers transmit and focus force to activate mechanosensitive channels. J Cell Sci 2008; 121:496-503. [DOI: 10.1242/jcs.022053] [Citation(s) in RCA: 206] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Mechanosensitive (MS) channels are expressed in various cells in a wide range of phylogenetic lineages from bacteria to humans. Understanding the molecular and biophysical mechanisms of their activation is an important research pursuit. It is controversial whether eukaryotic MS channels need accessory proteins – typically cytoskeletal structures – for activation, because MS channel activities are modulated by pharmacological treatments that affect the cytoskeleton. Here we demonstrate that direct mechanical stimulation (stretching) of an actin stress fiber using optical tweezers can activate MS channels in cultured human umbilical vein endothelial cells (HUVECs). Furthermore, by using high-speed total internal reflection microscopy, we visualized spots of Ca2+ influx across individual MS channels distributed near focal adhesions in the basal surface of HUVECs. This study provides the first direct evidence that the cytoskeleton works as a force-transmitting and force-focusing molecular device to activate MS channels in eukaryotic cells.
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Affiliation(s)
- Kimihide Hayakawa
- Cell Mechano-sensing Project ICORP/SORST, Japan Science and Technology Agency, Nagoya University Graduate School of Medicine, 65 Tsurumai Syouwa-ku, Nagoya 468-8550, Japan
| | - Hitoshi Tatsumi
- Cell Mechano-sensing Project ICORP/SORST, Japan Science and Technology Agency, Nagoya University Graduate School of Medicine, 65 Tsurumai Syouwa-ku, Nagoya 468-8550, Japan
- Department of Physiology, Nagoya University Graduate School of Medicine, 65 Tsurumai Syouwa-ku, Nagoya 468-8550, Japan
| | - Masahiro Sokabe
- Cell Mechano-sensing Project ICORP/SORST, Japan Science and Technology Agency, Nagoya University Graduate School of Medicine, 65 Tsurumai Syouwa-ku, Nagoya 468-8550, Japan
- Department of Physiology, Nagoya University Graduate School of Medicine, 65 Tsurumai Syouwa-ku, Nagoya 468-8550, Japan
- Department of Molecular Physiology, National Institute for Physiological Sciences, NINS, Myodaiji, Okazaki 444-8585, Japan
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44
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Ito S, Kume H, Naruse K, Kondo M, Takeda N, Iwata S, Hasegawa Y, Sokabe M. A novel Ca2+ influx pathway activated by mechanical stretch in human airway smooth muscle cells. Am J Respir Cell Mol Biol 2007; 38:407-13. [PMID: 17975175 DOI: 10.1165/rcmb.2007-0259oc] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
In response to mechanical stretch, airway smooth muscle exhibits various cellular functions such as contraction, proliferation, and cytoskeletal remodeling, all of which are implicated in the pathophysiology of asthma. We tested the hypothesis that mechanical stretch of airway smooth muscle cells increases intracellular Ca(2+) concentration ([Ca(2+)](i)) by activating stretch-activated (SA) nonselective cation channels. A single uniaxial stretch (3 s) was given to human bronchial smooth muscle cells cultured on an elastic silicone membrane. After the mechanical stretch, a transient increase in [Ca(2+)](i) was observed. The [Ca(2+)](i) increase was significantly dependent on stretch amplitude. The augmented [Ca(2+)](i) due to stretch was completely abolished by removal of extracellular Ca(2+) and was markedly attenuated by an application of Gd(3+), an inhibitor of SA channels, or ruthenium red, a transient receptor potential vanilloid (TRPV) inhibitor. In contrast, the stretch-induced rises of [Ca(2+)](i) were not altered by other Ca(2+) channel inhibitors such as nifedipine, BTP-2, and SKF-96365. Moreover, the [Ca(2+)](i) increases were not affected by indomethacin, a cyclooxygenase inhibitor, U-73122, a phospholipase C inhibitor, or xestospongin C, an inhibitor of the inositol-trisphosphate receptor. These findings demonstrate that a novel Ca(2+) influx pathway activated by mechanical stretch, possibly through the Ca(2+)-permeable SA channel activated directly by stretch rather than by indirect mechanisms via intracellular messenger production, is involved in human airway smooth muscle cells. A molecular candidate for the putative SA channel may be one of the members of the TRPV channel family. Thus, abnormal Ca(2+) homeostasis in response to excessive mechanical strain would contribute to the pathogenesis of asthma.
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Affiliation(s)
- Satoru Ito
- Department of Respiratory Medicine, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan
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45
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Zhang YA, Tuft RA, Lifshitz LM, Fogarty KE, Singer JJ, Zou H. Caffeine-activated large-conductance plasma membrane cation channels in cardiac myocytes: characteristics and significance. Am J Physiol Heart Circ Physiol 2007; 293:H2448-61. [PMID: 17483243 DOI: 10.1152/ajpheart.00032.2007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Caffeine-activated, large-conductance, nonselective cation channels (LCCs) have been found in the plasma membrane of isolated cardiac myocytes in several species. However, little is known about the effects of opening these channels. To examine such effects and to further understand the caffeine-activation mechanism, we carried out studies using whole-cell patch-clamp techniques with freshly isolated cardiac myocytes from rats and mice. Unlike previous studies, thapsigargin was used so that both the effect of opening LCCs and the action of caffeine were independent of Ca2+ release from intracellular stores. These Ca2+-permeable LCCs were found in a majority of the cells from atria and ventricles, with a conductance of ∼370 pS in rat atria. Caffeine and all its direct metabolic products (theophylline, theobromine, and paraxanthine) activated the channel, while isocaffeine did not. Although they share some similarities with ryanodine receptors (RyRs, the openings of which give rise to Ca2+ sparks), LCCs also showed some different characteristics. With simultaneous Ca2+ imaging and current recording, the localized fluorescence increase due to Ca2+ entry through a single opening of an LCC (SCCaFT) was detected. When membrane potential, instead of current, was recorded, SCCaFT-like fluorescence transients (indicating single LCC openings) were found to accompany membrane depolarizations. To our knowledge, this is the first report directly linking membrane potential changes to a single opening of an ion channel. Moreover, these events in cardiac cells suggest a possible additional mechanism by which caffeine and theophylline contribute to the generation of cardiac arrhythmias.
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Affiliation(s)
- Yu-An Zhang
- Department of Physiology, University of Massachusetts Medical School, Worcester, MA 01655, USA
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46
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Sandoval RJ, Injeti ER, Williams JM, Georthoffer WT, Pearce WJ. Myogenic contractility is more dependent on myofilament calcium sensitization in term fetal than adult ovine cerebral arteries. Am J Physiol Heart Circ Physiol 2007; 293:H548-56. [PMID: 17384133 DOI: 10.1152/ajpheart.00134.2007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Regulation of cytosolic calcium and myofilament calcium sensitivity varies considerably with postnatal age in cerebral arteries. Because these mechanisms also govern myogenic tone, the present study used graded stretch to examine the hypothesis that myogenic tone is less dependent on calcium influx and more dependent on myofilament calcium sensitization in term fetal compared with adult cerebral arteries. Term fetal and adult posterior communicating cerebral arteries exhibited similar myogenic responses, with peak tensions averaging 24 and 26% of maximum contractile force produced in any given tissue in response to an isotonic Krebs buffer containing 122 mM K+ (Kmax) at optimum stretch ratios (working diameter/unstressed diameter) of 2.19 and 2.23, respectively. Graded stretch increased cytosolic Ca2+ concentration at stretch ratios >2.0 in adult arteries, but increased Ca2+ concentration only at stretch ratios >2.3 in fetal arteries. In permeabilized arteries, myogenic tone peaked at a stretch ratio of 2.1 in both fetal and adult arteries. The fetal %Kmax values at peak myogenic tone were not significantly different at either pCa 7.0 (23%) or pCa 5.5 (25%) but were significantly less at pCa 8.0 (8.4 ± 2.3%). Conversely, adult %Kmax values at peak myogenic tone were significantly less at both pCa 8.0 (10.4 ± 1.8%) and pCa 7.0 (16%) than at pCa 5.5 (27%). The maximal extents of stretch-induced increases in myosin light chain phosphorylation in intact fetal (20%) and adult (17%) arteries were similar. The data demonstrate that the cerebrovascular myogenic response is highly conserved during postnatal maturation but is mediated differently in fetal and adult cerebral arteries.
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Affiliation(s)
- Renan J Sandoval
- Department of Physiology and Pharmacology, Center for Perinatal Biology, Loma Linda University School of Medicine, Loma Linda, CA 92354, USA
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47
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Navedo MF, Amberg GC, Westenbroek RE, Sinnegger-Brauns MJ, Catterall WA, Striessnig J, Santana LF. Ca(v)1.3 channels produce persistent calcium sparklets, but Ca(v)1.2 channels are responsible for sparklets in mouse arterial smooth muscle. Am J Physiol Heart Circ Physiol 2007; 293:H1359-70. [PMID: 17526649 DOI: 10.1152/ajpheart.00450.2007] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Ca(2+) sparklets are local elevations in intracellular Ca(2+) produced by the opening of a single or a cluster of L-type Ca(2+) channels. In arterial myocytes, Ca(2+) sparklets regulate local and global intracellular Ca(2+). At present, the molecular identity of the L-type Ca(2+) channels underlying Ca(2+) sparklets in these cells is undetermined. Here, we tested the hypotheses that voltage-gated calcium channel-alpha 1.3 subunit (Ca(v)1.3) can produce Ca(2+) sparklets and that Ca(v)1.2 and/or Ca(v)1.3 channels are responsible for Ca(2+) sparklets in mouse arterial myocytes. First, we investigated the functional properties of single Ca(v)1.3 channels in tsA201 cells. With 110 mM Ba(2+) as the charge carrier, Ca(v)1.3 channels had a conductance of 20 pS. This value is similar to that of Ca(v)1.2 and native L-type Ca(2+) channels. As previously shown for Ca(v)1.2 channels, Ca(v)1.3 channels can operate in two gating modes characterized by short and long open times. Expressed Ca(v)1.3 channels also produced Ca(2+) sparklets. Ca(v)1.3 sparklets had properties similar to those produced by Ca(v)1.2 and native L-type channels, including quantal amplitude, dihydropyridine sensitivity, bimodal gating, and dual-event duration times. However, the voltage dependencies of conductance and steady-state inactivation of the Ca(2+) current (I(Ca)) in arterial myocytes were similar to those recorded from cells expressing Ca(v)1.2 but not Ca(v)1.3 channels. Furthermore, nifedipine (10 microM) eliminated Ca(2+) sparklets in wild-type myocytes but not in myocytes expressing dihydropyridine-insensitive Ca(v)1.2 channels. Accordingly, Ca(v)1.3 transcript and protein were not detected in isolated arterial myocytes. We conclude that although Ca(v)1.3 channels can produce Ca(2+) sparklets, Ca(v)1.2 channels underlie I(Ca), Ca(2+) sparklets, and hence dihydropyridine-sensitive Ca(2+) influx in mouse arterial myocytes.
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MESH Headings
- Animals
- Calcium/metabolism
- Calcium Channel Blockers/pharmacology
- Calcium Channels, L-Type/drug effects
- Calcium Channels, L-Type/physiology
- Calcium Signaling/physiology
- Cells, Cultured
- Electrophysiology
- Mice
- Mice, Inbred C57BL
- Mice, Mutant Strains
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Myocytes, Smooth Muscle/cytology
- Myocytes, Smooth Muscle/drug effects
- Myocytes, Smooth Muscle/metabolism
- Nifedipine/pharmacology
- Patch-Clamp Techniques
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Affiliation(s)
- Manuel F Navedo
- Department of Physiology and Biophysics, University of Washington, Box 357290, Seattle, WA 98195, USA
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48
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Kitsiopoulou E, Hatziefthimiou AA, Gourgoulianis KI, Molyvdas PA. Resting tension affects eNOS activity in a calcium-dependent way in airways. Mediators Inflamm 2007; 2007:24174. [PMID: 17515950 PMCID: PMC1868075 DOI: 10.1155/2007/24174] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2006] [Accepted: 02/05/2007] [Indexed: 11/18/2022] Open
Abstract
The alteration of resting tension (RT) from 0.5 g to 2.5 g increased significantly airway smooth muscle contractions induced by acetylcholine (ACh) in rabbit trachea. The decrease in extracellular calcium concentration [Ca2+]o from 2 mM to 0.2 mM reduced ACh-induced contractions only at 2.5 g RT with no effect at 0.5 g RT. The nonselective inhibitor of nitric oxide synthase (NOS), NG-nitro-L-arginine methyl ester (L-NAME) increased ACh-induced contractions at
2.5 g RT. The inhibitor of inducible NOS, S-methylsothiourea or neuronal
NOS, 7-nitroindazole had no effect. At 2.5 g RT, the reduction of [Ca2+]o from 2 mM to 0.2 mM abolished the effect of L-NAME on ACh-induced contractions. The NO precursor L-arginine or the tyrosine kinase inhibitors erbstatin A and genistein had no effect on ACh-induced contractions obtained at 2.5 g RT. Our results suggest that in airways, RT affects ACh-induced contractions by modulating the activity of epithelial NOS in a calcium-dependent, tyrosine-phosphorylation-independent way.
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Affiliation(s)
- Eudoxia Kitsiopoulou
- Department of Physiology, Medical School, University of Thessaly, Papakiriazi 22, 41222 Larissa, Greece
| | - Apostolia A. Hatziefthimiou
- Department of Physiology, Medical School, University of Thessaly, Papakiriazi 22, 41222 Larissa, Greece
- *Apostolia A. Hatziefthimiou:
| | | | - Paschalis-Adam Molyvdas
- Department of Physiology, Medical School, University of Thessaly, Papakiriazi 22, 41222 Larissa, Greece
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Abstract
The excitability of smooth muscle cells is regulated, in part, by stretch-activated ion channels in the plasma membrane. The response to stretch of a particular muscle or organ is tuned to specific functional needs by the types of ion channels expressed. Mechanosensitive ionic conductances that yield either inward or outward currents have been observed in and characterized in studies of smooth muscles. In vascular muscles, the dominant response to stretch is muscle contraction (the myogenic response). This chapter proposes several mechanisms for the myogenic response; one of these hypotheses involves stretch-dependent activation of nonselective cation channels. The inward current resulting from an activation of these channels causes plasma membrane depolarization, activation of voltage-gated Ca(2+) channels, Ca(2+) entry, and excitation-contraction coupling. Thus, increasing the vascular pressure and distension of blood vessels cause responsive vasoconstriction. Other conductances are also proposed as participants in the myogenic response, and progress characterizing the inward current channels responsive to stretch is summarized. Outward currents responding to muscle stretch are also present in smooth muscles. For example, expression of stretch-sensitive two-pore domain K(+) (K2P) channels has been reported in visceral smooth muscles. These organs resist contraction on filling and provide a reservoir function. Stretch-dependent outward current channels are hypothesized to help stabilize membrane potential until it becomes desirable to empty the stored contents. Mechanosensitive conductances participate in the integrated responses of smooth muscle tissues. The chapter summarizes the class of channels found in smooth muscles.
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50
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Uhrenholt TR, Schjerning J, Vanhoutte PM, Jensen BL, Skøtt O. Intercellular calcium signaling and nitric oxide feedback during constriction of rabbit renal afferent arterioles. Am J Physiol Renal Physiol 2007; 292:F1124-31. [PMID: 17148782 DOI: 10.1152/ajprenal.00420.2006] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Vasoconstriction and increase in the intracellular calcium concentration ([Ca2+]i) of vascular smooth muscle cells may cause an increase of endothelial cell [Ca2+]i, which, in turn, augments nitric oxide (NO) production and inhibits smooth muscle cell contraction. This hypothesis was tested in microperfused rabbit renal afferent arterioles, using fluorescence imaging microscopy with the calcium-sensitive dye fura-2 and the NO-sensitive dye 4-amino-5-methylamino-2′,7′-difluorescein. Both dyes were loaded into smooth muscle and endothelium. Depolarization with 100 mmol/l KCl led to a transient vasoconstriction which was converted into a sustained response by N-nitro-l-arginine methyl ester (l-NAME). Depolarization increased smooth muscle cell [Ca2+]ifrom 162 ± 15 nmol/l to a peak of 555 ± 70 nmol/l ( n = 7), and this response was inhibited by 80% by the l-type calcium channel blocker calciseptine. After a delay of 10 s, [Ca2+]iincreased in endothelial cells immediately adjacent to reactive smooth muscle cells, and this calcium wave spread in a nonregenerative fashion laterally into the endothelial cell layer with a velocity of 1.2 μm/s. Depolarization with 100 mmol/l KCl led to a significant increase in NO production ([NO]i) which was inhibited by l-NAME ( n = 5). Acetylcholine caused a rapid increase in endothelial [Ca2+]i, which did not transfer to the smooth muscle cells. l-NAME treatment did not affect changes in smooth muscle [Ca2+]iafter depolarization, but it did increase the calcium sensitivity of the contractile apparatus. We conclude that depolarization increases smooth muscle [Ca2+]iwhich is transferred to the endothelial cells and stimulates NO production which curtails vasoconstriction by reducing the calcium sensitivity of the contractile apparatus.
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Affiliation(s)
- T R Uhrenholt
- Physiology and Pharmacology, Univ. of Southern Denmark, DK-5000 Odense, Denmark
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