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Forzisi E, Sesti F. Non-conducting functions of ion channels: The case of integrin-ion channel complexes. Channels (Austin) 2022; 16:185-197. [PMID: 35942524 PMCID: PMC9364710 DOI: 10.1080/19336950.2022.2108565] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Started as an academic curiosity more than two decades ago, the idea that ion channels can regulate cellular processes in ways that do not depend on their conducting properties (non-ionic functions) gained traction and is now a flourishing area of research. Channels can regulate physiological processes including actin cytoskeletal remodeling, cell motility, excitation-contraction coupling, non-associative learning and embryogenesis, just to mention some, through non-ionic functions. When defective, non-ionic functions can give rise to channelopathies involved in cancer, neurodegenerative disease and brain trauma. Ion channels exert their non-ionic functions through a variety of mechanisms that range from physical coupling with other proteins, to possessing enzymatic activity, to assembling with signaling molecules. In this article, we take stock of the field and review recent findings. The concept that emerges, is that one of the most common ways through which channels acquire non-ionic attributes, is by assembling with integrins. These integrin-channel complexes exhibit broad genotypic and phenotypic heterogeneity and reveal a pleiotropic nature, as they appear to be capable of influencing both physiological and pathological processes.
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Affiliation(s)
- Elena Forzisi
- Department of Neuroscience and Cell Biology, Robert Wood Johnson Medical School, Rutgers University, NJ, USA
| | - Federico Sesti
- Department of Neuroscience and Cell Biology, Robert Wood Johnson Medical School, Rutgers University, NJ, USA
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Chioccioli Altadonna G, Montalbano A, Iorio J, Becchetti A, Arcangeli A, Duranti C. The Interaction between hERG1 and β1 Integrins Modulates hERG1 Current in Different Pathological Cell Models. MEMBRANES 2022; 12:1162. [PMID: 36422154 PMCID: PMC9698864 DOI: 10.3390/membranes12111162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/08/2022] [Revised: 11/13/2022] [Accepted: 11/16/2022] [Indexed: 06/16/2023]
Abstract
Ion channels are implicated in various diseases, including cancer, in which they modulate different aspects of cancer progression. In particular, potassium channels are often aberrantly expressed in cancers, a major example being provided by hERG1. The latter is generally complexed with β1 integrin in tumour cells, and such a molecular complex represents a new druggable hub. The present study focuses on the characterization of the functional consequences of the interaction between hERG1 and β1 integrins on different substrates over time. To this purpose, we studied the interplay alteration on the plasma membrane through patch clamp techniques in a cellular model consisting of human embryonic kidney (HEK) cells stably transfected with hERG1 and in a cancer cell model consisting of SH-SY5Y neuroblastoma cells, endogenously expressing the channel. Cells were seeded on different substrates known to stimulate β1 integrins, such as fibronectin (FN) for HEK-hERG1 and laminin (LMN) for SH-SY5Y. In HEK cells stably overexpressing hERG1, we observed a hERG1 current density increase accompanied by Vrest hyperpolarization after cell seeding onto FN. Notably, a similar behaviour was shown by SH-SY5Y neuroblastoma cells plated onto LMN. Interestingly, we did not observe this phenomenon when plating the cells on substrates such as Bovine Serum Albumin (BSA) or Polylysine (PL), thus suggesting a crucial involvement of ECM proteins as well as of β1 integrin activation.
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Affiliation(s)
| | - Alberto Montalbano
- Department of Experimental and Clinical Medicine, University of Firenze, Viale G.B. Morgagni 50, 50134 Firenze, Italy
| | - Jessica Iorio
- Department of Experimental and Clinical Medicine, University of Firenze, Viale G.B. Morgagni 50, 50134 Firenze, Italy
| | - Andrea Becchetti
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza 2, 20126 Milano, Italy
| | - Annarosa Arcangeli
- Department of Experimental and Clinical Medicine, University of Firenze, Viale G.B. Morgagni 50, 50134 Firenze, Italy
| | - Claudia Duranti
- Department of Experimental and Clinical Medicine, University of Firenze, Viale G.B. Morgagni 50, 50134 Firenze, Italy
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Stock C, Ludwig FT, Hanley PJ, Schwab A. Roles of ion transport in control of cell motility. Compr Physiol 2013; 3:59-119. [PMID: 23720281 DOI: 10.1002/cphy.c110056] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Cell motility is an essential feature of life. It is essential for reproduction, propagation, embryonic development, and healing processes such as wound closure and a successful immune defense. If out of control, cell motility can become life-threatening as, for example, in metastasis or autoimmune diseases. Regardless of whether ciliary/flagellar or amoeboid movement, controlled motility always requires a concerted action of ion channels and transporters, cytoskeletal elements, and signaling cascades. Ion transport across the plasma membrane contributes to cell motility by affecting the membrane potential and voltage-sensitive ion channels, by inducing local volume changes with the help of aquaporins and by modulating cytosolic Ca(2+) and H(+) concentrations. Voltage-sensitive ion channels serve as voltage detectors in electric fields thus enabling galvanotaxis; local swelling facilitates the outgrowth of protrusions at the leading edge while local shrinkage accompanies the retraction of the cell rear; the cytosolic Ca(2+) concentration exerts its main effect on cytoskeletal dynamics via motor proteins such as myosin or dynein; and both, the intracellular and the extracellular H(+) concentration modulate cell migration and adhesion by tuning the activity of enzymes and signaling molecules in the cytosol as well as the activation state of adhesion molecules at the cell surface. In addition to the actual process of ion transport, both, channels and transporters contribute to cell migration by being part of focal adhesion complexes and/or physically interacting with components of the cytoskeleton. The present article provides an overview of how the numerous ion-transport mechanisms contribute to the various modes of cell motility.
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Affiliation(s)
- Christian Stock
- Institute of Physiology II, University of Münster, Münster, Germany.
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Sheridan EJ, Austin CJD, Aitken JB, Vogt S, Jolliffe KA, Harris HH, Rendina LM. Synchrotron X-ray fluorescence studies of a bromine-labelled cyclic RGD peptide interacting with individual tumor cells. JOURNAL OF SYNCHROTRON RADIATION 2013; 20:226-33. [PMID: 23412478 PMCID: PMC3943546 DOI: 10.1107/s0909049513001647] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/30/2012] [Accepted: 01/16/2013] [Indexed: 06/01/2023]
Abstract
The first example of synchrotron X-ray fluorescence imaging of cultured mammalian cells in cyclic peptide research is reported. The study reports the first quantitative analysis of the incorporation of a bromine-labelled cyclic RGD peptide and its effects on the biodistribution of endogenous elements (for example, K and Cl) within individual tumor cells.
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Affiliation(s)
- Erin J. Sheridan
- School of Chemistry, The University of Sydney, Sydney, NSW 2006, Australia
| | | | - Jade B. Aitken
- School of Chemistry, The University of Sydney, Sydney, NSW 2006, Australia
- Australian Synchrotron, Clayton, Victoria 3168, Australia
- Institute of Materials Structure Science, KEK, Tsukuba, Ibaraki 305-0801, Japan
| | - Stefan Vogt
- X-ray Science Division, Argonne National Laboratory, Argonne, IL 60439, USA
| | | | - Hugh H. Harris
- School of Chemistry and Physics, The University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Louis M. Rendina
- School of Chemistry, The University of Sydney, Sydney, NSW 2006, Australia
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5
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Schwab A, Fabian A, Hanley PJ, Stock C. Role of ion channels and transporters in cell migration. Physiol Rev 2013; 92:1865-913. [PMID: 23073633 DOI: 10.1152/physrev.00018.2011] [Citation(s) in RCA: 315] [Impact Index Per Article: 28.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Cell motility is central to tissue homeostasis in health and disease, and there is hardly any cell in the body that is not motile at a given point in its life cycle. Important physiological processes intimately related to the ability of the respective cells to migrate include embryogenesis, immune defense, angiogenesis, and wound healing. On the other side, migration is associated with life-threatening pathologies such as tumor metastases and atherosclerosis. Research from the last ≈ 15 years revealed that ion channels and transporters are indispensable components of the cellular migration apparatus. After presenting general principles by which transport proteins affect cell migration, we will discuss systematically the role of channels and transporters involved in cell migration.
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New insights into the regulation of ion channels by integrins. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2010; 279:135-90. [PMID: 20797679 DOI: 10.1016/s1937-6448(10)79005-5] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
By controlling cell adhesion to the extracellular matrix, integrin receptors regulate processes as diverse as cell migration, proliferation, differentiation, apoptosis, and synaptic stability. Because the underlying mechanisms are generally accompanied by changes in transmembrane ion flow, a complex interplay occurs between integrins, ion channels, and other membrane transporters. This reciprocal interaction regulates bidirectional signal transduction across the cell surface and may take place at all levels of control, from transcription to direct conformational coupling. In particular, it is becoming increasingly clear that integrin receptors form macromolecular complexes with ion channels. Besides contributing to the membrane localization of the channel protein, the integrin/channel complex can regulate a variety of downstream signaling pathways, centered on regulatory proteins like tyrosine kinases and small GTPases. In turn, the channel protein usually controls integrin activation and expression. We review some recent advances in the field, with special emphasis on hematology and neuroscience. Some oncological implications are also discussed.
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Physical and Functional Interaction between Integrins and hERG1 Channels in Cancer Cells. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 674:55-67. [DOI: 10.1007/978-1-4419-6066-5_6] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Guasti L, Crociani O, Redaelli E, Pillozzi S, Polvani S, Masselli M, Mello T, Galli A, Amedei A, Wymore RS, Wanke E, Arcangeli A. Identification of a posttranslational mechanism for the regulation of hERG1 K+ channel expression and hERG1 current density in tumor cells. Mol Cell Biol 2008; 28:5043-60. [PMID: 18559421 PMCID: PMC2519704 DOI: 10.1128/mcb.00304-08] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2008] [Revised: 03/25/2008] [Accepted: 06/04/2008] [Indexed: 01/19/2023] Open
Abstract
A common feature of tumor cells is the aberrant expression of ion channels on their plasma membrane. The molecular mechanisms regulating ion channel expression in cancer cells are still poorly known. K(+) channels that belong to the human ether-a-go-go-related gene 1 (herg1) family are frequently misexpressed in cancer cells compared to their healthy counterparts. We describe here a posttranslational mechanism for the regulation of hERG1 channel surface expression in cancer cells. This mechanism is based on the activity of hERG1 isoforms containing the USO exon. These isoforms (i) are frequently overexpressed in human cancers, (ii) are retained in the endoplasmic reticulum, and (iii) form heterotetramers with different proteins of the hERG family. (iv) The USO-containing heterotetramers are retained intracellularly and undergo ubiquitin-dependent degradation. This process results in decreased hERG1 current (I(hERG1)) density. We detailed such a mechanism in heterologous systems and confirmed its functioning in tumor cells that endogenously express hERG1 proteins. The silencing of USO-containing hERG1 isoforms induces a higher I(hERG1) density in tumors, an effect that apparently regulates neurite outgrowth in neuroblastoma cells and apoptosis in leukemia cells.
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Affiliation(s)
- Leonardo Guasti
- Department of Experimental Pathology and Oncology, University of Florence, Viale G. B. Morgagni 50, 50134 Florence, Italy
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9
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Cherubini A, Hofmann G, Pillozzi S, Guasti L, Crociani O, Cilia E, Di Stefano P, Degani S, Balzi M, Olivotto M, Wanke E, Becchetti A, Defilippi P, Wymore R, Arcangeli A. Human ether-a-go-go-related gene 1 channels are physically linked to beta1 integrins and modulate adhesion-dependent signaling. Mol Biol Cell 2005; 16:2972-83. [PMID: 15800067 PMCID: PMC1142440 DOI: 10.1091/mbc.e04-10-0940] [Citation(s) in RCA: 120] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Adhesive receptors of the integrin family are primarily involved in cell-extracellular matrix adhesion. Additionally, integrins trigger multiple signaling pathways that are involved in cell migration, proliferation, survival, and differentiation. We previously demonstrated that the activation of integrins containing the beta(1) subunit leads to a selective increase in potassium currents carried by the human ether-a-go-go-related gene (hERG) channels in neuroblastoma and leukemia cells; this current activation modulates adhesion-dependent differentiation in these cells. We hypothesized that the cross-talk between integrins and hERG channels could be traced back to the assembly of a macromolecular signaling complex comprising the two proteins. We tested this hypothesis in both SH-SY5Y neuroblastoma cells and in human embryonic kidney 293 cells stably transfected with hERG1 and, therefore, expressing only the full-length hERG1 protein on the plasma membrane. The beta(1) integrin and hERG1 coprecipitate in these cells and colocalize in both intracellular and surface membrane compartments. The two proteins also coprecipitate with caveolin-1, suggesting the localization of the complex in lipid rafts/caveolae. hERG1-transfected cells undergo an activation of hERG currents after beta(1) integrin-mediated adhesion to fibronectin; concomitant with this activation, the focal adhesion kinase associates with the hERG1 protein and becomes tyrosine phosphorylated. Using hERG1-specific inhibitors, we show that the tyrosine phosphorylation of focal adhesion kinase is strictly dependent on hERG channel activity. Similarly, the activity of the small GTPase Rac1 turned out to be dependent on hERG currents. On the whole, these data indicate that the hERG1 protein associates with beta(1) integrins and modulates adhesion receptor signaling.
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Affiliation(s)
- Alessia Cherubini
- Department of Experimental Pathology and Oncology, University of Firenze, 50134 Firenze, Italy
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10
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Arcangeli A, Becchetti A, Cherubini A, Crociani O, Defilippi P, Guasti L, Hofmann G, Pillozzi S, Olivotto M, Wanke E. Physical and functional interaction between integrins and hERG potassium channels. Biochem Soc Trans 2004; 32:826-7. [PMID: 15494025 DOI: 10.1042/bst0320826] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Integrins are adhesion receptors capable of transmitting intracellular signals that regulate many different cellular functions. Among integrin-mediated signals, the activation of ion channels can be included. We demonstrated that a long-lasting activation of hERG (human ether-a-go-go-related gene) potassium channels occurs in both human neuroblastoma and leukaemia cells after the activation of the β1 integrin subunit. This activation is apparently a determining factor inducing neurite extension and osteoclastic differentiation in both the cell types. More recently, we provided evidences that β1 integrins and hERG channels co-precipitate in both the cell types. Preliminary results suggest that a macromolecular signalling complex indeed occurs between integrins and the hERG1 protein and that hERG channel activity can modulate integrin downstream signalling.
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Affiliation(s)
- A Arcangeli
- Department of Experimental Pathology and Oncology, University of Firenze, Italy.
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Abstract
Ether-à-go-go-related gene (erg) channels are voltage-dependent K+ channels mediating inward-rectifying K+ currents because of their peculiar gating kinetics. These characteristics are essential for repolarization of the cardiac action potential. Inherited and acquired malfunctioning of erg channels may lead to the long QT-syndrome. However, erg currents have also been recorded in many other excitable cells, like smooth muscle fibres of the gastrointestinal tract, neuroblastoma cells or neuroendocrine cells. In these cells erg currents contribute to the maintenance of the resting potential. Changes in the resting potential are related to cell-specific functions like increase in hormone secretion, frequency adaptation or increase in contractility.
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Affiliation(s)
- Jürgen R Schwarz
- Institut für Angewandte Physiologie, Zentrum für Experimentelle Medizin, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany.
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Avossa D, Rosato-Siri MD, Mazzarol F, Ballerini L. Spinal circuits formation: a study of developmentally regulated markers in organotypic cultures of embryonic mouse spinal cord. Neuroscience 2004; 122:391-405. [PMID: 14614905 DOI: 10.1016/j.neuroscience.2003.07.006] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
In this study, we have addressed the issue of neural circuit formation using the mouse spinal cord as a model system. Our primary objective was to assess the suitability of organotypic cultures from embryonic mouse spinal cord to investigate, during critical periods of spinal network formation, the role of the local spinal cellular environment in promoting circuit development and refinement. These cultures offer the great advantage over other in vitro systems, of preserving the basic cytoarchitecture and the dorsal-ventral orientation of the spinal segment from which they are derived [Eur J Neurosci 14 (2001) 903; Eur J Neurosci 16 (2002) 2123]. Long-term embryonic spinal cultures were developed and analyzed at sequential times in vitro, namely after 1, 2, and 3 weeks. Spatial and temporal regulation of neuronal and non-neuronal markers was investigated by immunocytochemical and Western blotting analysis using antibodies against: a) the non-phosphorylated epitope of neurofilament H (SMI32 antibody); b) the enzyme choline acetyltransferase, to localize motoneurons and cholinergic interneurons; c) the enzyme glutamic acid decarboxylase 67, to identify GABAergic interneurons; d) human eag-related gene (HERG) K(+) channels, which appear to be involved in early stages of neuronal and muscle development; e) glial fibrillary acidic protein, to identify mature astrocytes; f) myelin basic protein, to identify the onset of myelination by oligodendrocytes. To examine the development of muscle acetylcholine receptors clusters in vitro, we incubated live cultures with tetramethylrhodamine isothiocyanate-labeled alpha-bungarotoxin, and we subsequently immunostained them with SMI32 or with anti-myosin antibodies. Our results indicate that the developmental pattern of expression of these markers in organotypic cultures shows close similarities to the one observed in vivo. Therefore, spinal organotypic cultures provide a useful in vitro model system to study several aspects of neurogenesis, gliogenesis, muscle innervation, and synaptogenesis.
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Affiliation(s)
- D Avossa
- Biophysics Sector and Istituto Nazionale di Fisica della Materia Unit, International School for Advanced Studies (SISSA), via Beirut 2-4, 34014 Trieste, Italy.
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Abstract
Understanding the factors that allow biological systems to reliably self-assemble consistent, highly complex, four dimensional patterns on many scales is crucial for the biomedicine of cancer, regeneration, and birth defects. The role of chemical signaling factors in controlling embryonic morphogenesis has been a central focus in modern developmental biology. While the role of tensile forces is also beginning to be appreciated, another major aspect of physics remains largely neglected by molecular embryology: electromagnetic fields and radiations. The continued progress of molecular approaches to understanding biological form and function in the post genome era now requires the merging of genetics with functional understanding of biophysics and physiology in vivo. The literature contains much data hinting at an important role for bioelectromagnetic phenomena as a mediator of morphogenetic information in many contexts relevant to embryonic development. This review attempts to highlight briefly some of the most promising (and often underappreciated) findings that are of high relevance for understanding the biophysical factors mediating morphogenetic signals in biological systems. These data originate from contexts including embryonic development, neoplasm, and regeneration.
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Affiliation(s)
- Michael Levin
- Department of Cytokine Biology, The Forsyth Institute, Boston, Massachusetts 02114, USA.
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Vasilyev DV, Barish ME. Regulation of an inactivating potassium current (IA) by the extracellular matrix protein vitronectin in embryonic mouse hippocampal neurones. J Physiol 2003; 547:859-71. [PMID: 12562917 PMCID: PMC2342723 DOI: 10.1113/jphysiol.2002.036889] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Integrins are a class of intrinsic membrane receptors for extracellular matrix ligands. In the central nervous system, integrins and their ligands influence neuronal growth and synaptic function, but relatively little is known about their potential to regulate intrinsic excitability. To explore this area, we examined the effects of matrix components on potassium currents in developing mouse hippocampal neurones, using electrophysiological and immunochemical approaches. We tested the effects of three integrin ligands present in the hippocampus, fibronectin, laminin and vitronectin, on electrogenesis in late embryonic hippocampal pyramidal neurones. Explants cultured in serum-free medium were exposed to ligands (fibronectin at 3 microg ml-1, laminin at 5 microg ml-1, vitronectin at 10 microg ml-1) for 3-4 days, and voltage-gated potassium currents were recorded from presumptive CA3 pyramidal neurones. Of the three matrix components, only vitronectin affected potassium currents, selectively increasing the amplitude of the inactivating potassium current (IA, or A-current) by about 75 % over control levels, and its density (current per unit area) by about 40 % (measured after 3 day exposures from embryonic day 15.5). Other potassium currents were spared, except to the extent that membrane area was increased. The actions of vitronectin were sensitive to RGD (Arg-Gly-Asp)-sequence-containing peptide, indicating the involvement of integrins as vitronectin receptors. The kinetic properties of IA, including the voltage-dependence of activation and inactivation, inactivation rate and the rate of recovery from inactivation, were minimally affected by vitronectin and were consistent with enhanced functional expression of Kv4-family subunits. Analyses of Kv4.2 and Kv1.4 immunoreactivity also suggested a preferential increase in Kv4.2 levels, with lesser effects on Kv1.4 levels. These results indicate that vitronectin can selectively regulate IA, and together with other observations suggest that modulation of neuronal excitability by integrins and their ligands occurs commonly.
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Affiliation(s)
- Dmitry V Vasilyev
- Division of Neurosciences, Beckman Research Institute of the City of Hope, Duarte, CA 91010, USA
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Cheng SM, Chen I, Levin M. K(ATP) channel activity is required for hatching in Xenopus embryos. Dev Dyn 2002; 225:588-91. [PMID: 12454935 DOI: 10.1002/dvdy.10183] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
A growing body of work suggests that the activity of ion channels and pumps is an important regulatory factor in embryonic development. We are beginning to identify functional roles for proteins suggested by a survey of expression of ion channel and pump genes in Xenopus and chick embryos (Rutenberg et al. [2002] Dev Dyn 225, this issue). Here, we report that the ATP-sensitive K(+) channel protein is present in the hatching gland of Xenopus embryos; moreover, we show that its activity is necessary for hatching in Xenopus. Pharmacologic inhibition of K(ATP) channels not only specifically prevents the hatching process but also greatly reduces the endogenous expression of Connexin-30 in the hatching gland. Based on recent work which showed that gap-junctional communication mediated by Cx30 in the hatching gland was required for secretion of the hatching enzyme, we propose that K(ATP) channel activity is upstream of Cx30 expression and represents a necessary endogenous step in the hatching of the Xenopus embryo.
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Affiliation(s)
- Shing-Ming Cheng
- Cytokine Biology Department, Forsyth Institute, and Harvard University Department of Oral and Developmental Biology, Boston, Massachusetts 02115, USA
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16
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Cherubini A, Pillozzi S, Hofmann G, Crociani O, Guasti L, Lastraioli E, Polvani S, Masi A, Becchetti A, Wanke E, Olivotto M, Arcangeli A. HERG K+ channels and beta1 integrins interact through the assembly of a macromolecular complex. Ann N Y Acad Sci 2002; 973:559-61. [PMID: 12485929 DOI: 10.1111/j.1749-6632.2002.tb04701.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Affiliation(s)
- A Cherubini
- Department of Experimental Pathology and Oncology, University of Florence, Florence, Italy
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Artym VV, Petty HR. Molecular proximity of Kv1.3 voltage-gated potassium channels and beta(1)-integrins on the plasma membrane of melanoma cells: effects of cell adherence and channel blockers. J Gen Physiol 2002; 120:29-37. [PMID: 12084773 PMCID: PMC2311400 DOI: 10.1085/jgp.20028607] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Tumor cell membranes have multiple components that participate in the process of metastasis. The present study investigates the physical association of beta1-integrins and Kv1.3 voltage-gated potassium channels in melanoma cell membranes using resonance energy transfer (RET) techniques. RET between donor-labeled anti-beta1-integrin and acceptor-labeled anti-Kv1.3 channels was detected on LOX cells adherent to glass and fibronectin-coated coverslips. However, RET was not observed on LOX cells in suspension, indicating that molecular proximity of these membrane molecules is adherence-related. Several K(+) channel blockers, including tetraethylammonium, 4-aminopyridine, and verapamil, inhibited RET between beta1-integrins and Kv1.3 channels. However, the irrelevant K(+) channel blocker apamin had no effect on RET between beta1-integrins and Kv1.3 channels. Based on these findings, we speculate that the lateral association of Kv1.3 channels with beta1-integrins contributes to the regulation of integrin function and that channel blockers might affect tumor cell behavior by influencing the assembly of supramolecular structures containing integrins.
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Affiliation(s)
- Vira V Artym
- Department of Biological Sciences, Wayne State University, Detroit, MI 48202, USA
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18
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Hofmann G, Bernabei PA, Crociani O, Cherubini A, Guasti L, Pillozzi S, Lastraioli E, Polvani S, Bartolozzi B, Solazzo V, Gragnani L, Defilippi P, Rosati B, Wanke E, Olivotto M, Arcangeli A. HERG K+ channels activation during beta(1) integrin-mediated adhesion to fibronectin induces an up-regulation of alpha(v)beta(3) integrin in the preosteoclastic leukemia cell line FLG 29.1. J Biol Chem 2001; 276:4923-31. [PMID: 11080495 DOI: 10.1074/jbc.m005682200] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Integrin receptors have been demonstrated to mediate either "inside-to-out" and "outside-to-in" signals, and by this way are capable of regulating many cellular functions, such as cell growth and differentiation, cell migration, and activation. Among the various integrin-centered signaling pathways discovered so far, we demonstrated that the modulation of the electrical potential of the plasma membrane (V(REST)) is an early integrin-mediated signal, which is related to neurite emission in neuroblastoma cells. This modulation is sustained by the activation of HERG K(+) channels, encoded by the ether-à-go-go-related gene (herg). The involvement of integrin-mediated signaling is being discovered in the hemopoietic system: in particular, osteoclasts are generated as well as induced to differentiate by interaction of osteoclast progenitors with the stromal cells, through the involvement of integrin receptors. We studied the effects of cell interaction with the extracellular matrix protein fibronectin (FN) in a human leukemic preosteoclastic cell line (FLG 29.1 cells), which has been demonstrated to express HERG currents. We report here that FLG 29.1 cells indeed adhere to purified FN through integrin receptors, and that this adhesion induces an osteoclast phenotype in these cells, as evidenced by the appearance of tartrate-resistant acid phosphatase, as well as by the increased expression of CD51/alpha(v)beta(3) integrin and calcitonin receptor. An early activation of HERG current (I(HERG)), without any increase in herg RNA or modifications of HERG protein was also observed in FN-adhering cells. This activation is apparently sustained by the beta(1) integrin subunit activation, through the involvement of a pertussis-toxin sensitive G(i) protein, and appears to be a determinant signal for the up-regulation of alpha(v)beta(3) integrin, as well as for the increased expression of calcitonin receptor.
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Affiliation(s)
- G Hofmann
- Department of Experimental Pathology and Oncology, University of Firenze, Viale G. B. Morgagni, 50, 50134 Florence, Italy
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Papadaki M, Bursac N, Langer R, Merok J, Vunjak-Novakovic G, Freed LE. Tissue engineering of functional cardiac muscle: molecular, structural, and electrophysiological studies. Am J Physiol Heart Circ Physiol 2001; 280:H168-78. [PMID: 11123231 DOI: 10.1152/ajpheart.2001.280.1.h168] [Citation(s) in RCA: 218] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The primary aim of this study was to relate molecular and structural properties of in vitro reconstructed cardiac muscle with its electrophysiological function using an in vitro model system based on neonatal rat cardiac myocytes, three-dimensional polymeric scaffolds, and bioreactors. After 1 wk of cultivation, we found that engineered cardiac muscle contained a 120- to 160-microm-thick peripheral region with cardiac myocytes that were electrically connected through gap junctions and sustained macroscopically continuous impulse propagation over a distance of 5 mm. Molecular, structural, and electrophysiological properties were found to be interrelated and depended on specific model system parameters such as the tissue culture substrate, bioreactor, and culture medium. Native tissue and the best experimental group (engineered cardiac muscle cultivated using laminin-coated scaffolds, rotating bioreactors, and low-serum medium) were comparable with respect to the conduction velocity of propagated electrical impulses and spatial distribution of connexin43. Furthermore, the structural and electrophysiological properties of the engineered cardiac muscle, such as cellularity, conduction velocity, maximum signal amplitude, capture rate, and excitation threshold, were significantly improved compared with our previous studies.
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Affiliation(s)
- M Papadaki
- Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge 02139, Massachusetts
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20
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Sun QL, Wang J, Bookman RJ, Bixby JL. Growth cone steering by receptor tyrosine phosphatase delta defines a distinct class of guidance cue. Mol Cell Neurosci 2000; 16:686-95. [PMID: 11083928 DOI: 10.1006/mcne.2000.0893] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Receptor-type tyrosine phosphatases (RPTPs) are involved in pathfinding decisions by elongating axons, but how they function in these decisions remains unclear. A vertebrate RPTP, PTP-delta, is a neurite-promoting homophilic adhesion molecule; here we demonstrate chemoattraction of CNS growth cones by a locally applied gradient of soluble PTP-delta. The attractive effect of PTP-delta was abolished by inhibition of tyrosine phosphatase activity, but in contrast to other guidance proteins was unaffected by inhibition of cyclic nucleotide activities. Gradients of PTP-delta or of laminin-1 also promoted increases in the speed of growth cone migration, but laminin-1 did not steer growth cones. Our results indicate that PTP-delta is a chemoattractant for vertebrate CNS neurons in vitro and suggest that it represents a distinct class of guidance protein from those previously defined. Further, our data indicate that growth cone attraction is mechanistically distinct from increases in the speed of growth cone movement.
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Affiliation(s)
- Q L Sun
- Department of Pharmacology, University of Miami School of Medicine, 1600 NW 10 Avenue, Miami, Florida 33136, USA
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21
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Arcangeli A, Rosati B, Crociani O, Cherubini A, Fontana L, Passani B, Wanke E, Olivotto M. Modulation of HERG current andherg gene expression during retinoic acid treatment of human neuroblastoma cells: Potentiating effects of BDNF. ACTA ACUST UNITED AC 1999. [DOI: 10.1002/(sici)1097-4695(199908)40:2<214::aid-neu7>3.0.co;2-0] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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22
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Pancrazio JJ, Ma W, Grant GM, Shaffer KM, Kao WY, Liu QY, Manos P, Barker JL, Stenger DA. A role for inwardly rectifying K+ channels in differentiation of NG108-15 neuroblastoma � glioma cells. ACTA ACUST UNITED AC 1999. [DOI: 10.1002/(sici)1097-4695(199903)38:4<466::aid-neu3>3.0.co;2-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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23
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Kowtha VC, Bryant HJ, Pancrazio JJ, Stenger DA. Influence of extracellular matrix proteins on membrane potentials and excitability in NG108-15 cells. Neurosci Lett 1998; 246:9-12. [PMID: 9622195 DOI: 10.1016/s0304-3940(98)00193-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Previous studies have demonstrated that components of the extracellular matrix can induce neurite extension and cell adhesion in the neuroblastoma x glioma hybrid cell line, NG108-15. Using standard intracellular recording techniques, we examined the resting membrane potential (RMP) and membrane excitability of NG108-15 cells differentiated under serum-free media with representative extracellular matrix (ECM) protein components as the substrate. Surfaces coated with collagen IV and a laminin-1 synthetic peptide induced a significantly (P < 0.05) more hyperpolarized RMP than control polystyrene surfaces. For example, after > or =8 days in culture NG108-15 cells plated on polystyrene exhibited a RMP of -33.2+/-0.8 mV (mean+/-SEM, n=158 cells) whereas cells cultured on the laminin-1 peptide C16 and collagen IV showed a RMP of -37.6+/-0.7 mV (n=157) and -37.5+/-1.5 mV (n=68), respectively. Furthermore, the proportions of cells on ECM substrates showing membrane excitability, i.e. evoked action potentials (APs) and the capability for regular firing, were significantly greater compared to those cells cultured on polystyrene. Among excitable cells cultured on the different substrates, characteristics of the action potentials, such as AP duration, amplitude, and the maximum rate of rise, dV/dtMAX, were examined in detail. While little or no differences were observed between polystyrene and the laminin-1 peptide groups, significant differences in the AP parameters were apparent for collagen IV. For example, dV/dtMAX for polystyrene and the laminin-1 peptide C16 were only 71.7+/-24.5 V/s (n=11) and 59.0+/-8.9 V/s (n=9), respectively, whereas cells cultured on collagen IV surfaces exhibited a dV/dtMAX reaching 156.1+/-22.0 V/s (n=7). These data support a role for ECM components in the maintenance of the RMP and membrane excitability in NG108-15 cells.
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Affiliation(s)
- V C Kowtha
- Center for Bio/Molecular Science and Engineering, Naval Research Laboratory, Washington, DC 20375, USA
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Sonohara S, Mira-y-Lopez R, Brentani MM. Laminin and estradiol regulation of the plasminogen-activator system in MCF-7 breast-carcinoma cells. Int J Cancer 1998; 76:77-85. [PMID: 9533765 DOI: 10.1002/(sici)1097-0215(19980330)76:1<77::aid-ijc13>3.0.co;2-d] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
We have investigated the effects of laminin, on the plasminogen-activator system of MCF-7 breast-carcinoma cells. MCF-7 cells were incubated on plastic or laminin-coated wells, and medium and cell lysate aliquots were assayed for tissue-type (tPA) and urokinase-type plasminogen activator (uPA) by a chromogenic assay in combination with anti-uPA antibodies. Cells cultured on laminin displayed a 5-fold increase in tPA activity and a 2-fold decrease in uPA activity relative to cells on plastic. These effects could be mimicked by laminin fragment P1 but not by collagen I or fibronectin. tPA activity of cells treated with estradiol (10 nM) was 3-fold higher, that of cells on laminin treated with estradiol was 15-fold higher, than that of control. Northern-blot analysis showed that tPA mRNA levels were up-regulated by estradiol and laminin, whereas PAI-1 mRNA levels were down-regulated by laminin and not affected by E2. Concomitant treatment with laminin and estradiol, decreased PAI-1 mRNA and increased tPA mRNA levels, accounting for the synergistic increase in tPA activity. Laminin exerted only a modest (approx. 2-fold) inhibitory effect on uPA mRNA levels. In the breast-carcinoma cell line MDA-MB-231, down-regulation of PAI-1 and uPA mRNA by laminin was not observed. Adhesion assays indicated that alpha2beta1 is the predominant receptor for laminin in MCF-7 cells. MDA-MB-231 cells expressed alpha2 (54%) but this integrin is not used as a laminin receptor. These results support a role for alpha2beta1 in mediating interactions of MCF-7 with LN.
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Affiliation(s)
- S Sonohara
- Departamento de Radiologia de Faculdade de Medicina da USP, São Paulo, Brazil
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Arcangeli A, Rosati B, Cherubini A, Crociani O, Fontana L, Passani B, Wanke E, Olivotto M. Long-term exposure to retinoic acid induces the expression of IRK1 channels in HERG channel-endowed neuroblastoma cells. Biochem Biophys Res Commun 1998; 244:706-11. [PMID: 9535729 DOI: 10.1006/bbrc.1998.8319] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The modulation of inward K+ conductances was studied during neuronal differentiation of human SH-SY5Y neuroblastoma cells. Under standard culture conditions, these cells express the herg gene, and the HERG current is the main inward K+ current regulating their Vrest. After 10-20 days exposure to Retinoic Acid (RA), SH-SY5Y cells showed, in addition to HERG currents, a novel current characterized by inward rectification, dependence on the extracellular K+ concentration, and blockade by Cs+ and Ba2+, the main features of the IRK1 current. The appearance of this current is accompanied by a strong hyperpolarisation of Vrest. RT-PCR experiments confirmed that a transcript of the IRK1 (Kir 2.1) gene actually appears in SH-SY5Y cells treated for 10-20 days with RA. On the whole, data here presented demonstrate that RA-induced neuronal differentiation of neuroblastoma cells is accompanied by the switch from a HERG-driven to a IRK1-driven control of Vrest, similarly to what happens in normal differentiating neurons; however, in tumor cells, this switch does not imply the abolition of HERG channel expression.
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Affiliation(s)
- A Arcangeli
- Institute of General Pathology, University of Florence, Italy
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Arcangeli A, Rosati B, Cherubini A, Crociani O, Fontana L, Ziller C, Wanke E, Olivotto M. HERG- and IRK-like inward rectifier currents are sequentially expressed during neuronal development of neural crest cells and their derivatives. Eur J Neurosci 1997; 9:2596-604. [PMID: 9517465 DOI: 10.1111/j.1460-9568.1997.tb01689.x] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Quail neural crest cells were cultured in a differentiative medium to study the inward K+ channel profile in neuronal precursors at various stages of maturation. Between 12 and 24 h of culture, neural crest-derived neurons displayed, in addition to the previously described outward depolarization-activated K+ currents, an inward current enhanced in high K+ medium. A biophysical and pharmacological analysis led us to conclude that this inward K+ current is identical to that previously demonstrated in mouse and human neuroblastoma cell lines (I[IR]). This current (quail I[IR] or ql[IR]), which is active at membrane potentials positive to -35 mV, was blocked by Cs+ and by class III antiarrhythmic drugs, thus resembling the K+ current encoded by the human ether-a-gò-gò-related gene (HERG). At later stages of incubation (>48 h), neural crest-derived neurons underwent morphological and biochemical differentiation and expressed fast Na+ currents. At this stage the cells lost qI[IR], displaying instead a classical inward rectifier K+ (IRK) current (quail I[IRK] = qI[IRK]). This substitution was reflected in the resting potential (VREST), which became hyperpolarized by >20 mV compared with the 24 h cells. Neurons were also harvested from peripheral ganglia and other derivatives originating from the migration of neural crest cells, viz. ciliary ganglia, dorsal root ganglia, adrenal medulla and sympathetic chain ganglia. After brief culture following harvesting from young embryos, ganglionic neurons always expressed qI(IR). On the other hand, when ganglia were explanted from older embryos (7-12 days), briefly cultured neurons displayed the IRK-like current. Again, in all the above derivatives the qI(IR) substitution by qI(IRK) was accompanied by a 20 mV hyperpolarization of VREST. Together, these data indicate that the VREST of normal neuronal precursors is sequentially regulated by HERG- and IRK-like currents, suggesting that HERG-like channels mark an immature and transient stage of neuronal differentiation, probably the same stage frozen in neuroblastomas by neoplastic transformation.
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Affiliation(s)
- A Arcangeli
- Institute of General Pathology, University of Florence, Italy
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