1
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Kshatri A, Rivero-Pérez B, Giraldez T. Subunit-specific inhibition of BK channels by piperine. Biophys J 2023:S0006-3495(23)00558-1. [PMID: 37700524 DOI: 10.1016/j.bpj.2023.09.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2023] [Revised: 08/03/2023] [Accepted: 09/08/2023] [Indexed: 09/14/2023] Open
Abstract
Piperine is the principal alkaloid present in black pepper and is well-known for its diverse pharmacological effects, including inhibition of different ion channels. Large conductance Ca2+-activated K+ channels (BK) are widely expressed across several tissues and play a vital role in many physiological functions. In this study, we investigated the pharmacological effects of piperine on various BK channel subunit compositions (BKα, BKαβ1,4, BKαγ1,3) expressed in HEK293T cells. Piperine in zero Ca2+ reversibly inhibited currents from the pore-forming BKα channels in a dose-dependent manner with a half-maximal inhibitory concentration (IC50) of 4.8 μM. Elevating the internal Ca2+ concentration from 0 to 100 μM significantly attenuated the inhibitory effects of piperine on BKα channels. The mutation G311S in the pore domain failed to alter the modulatory effects of piperine, whereas deletion of the entire cytoplasmic domain from BKα channels ablated its inhibitory effects. Addition of either BKβ1 or β4 regulatory subunits did not alter the efficacy of piperine on BKα channels. Interestingly, co-expression of either BKγ1 or BKγ3 subunits greatly diminished the ability of piperine to inhibit BKα channels. Our findings demonstrate that piperine is a potent natural modulator of BKα/BKαβ1,4 subunits but not BKαγ1,3 subunits. The mechanism of piperine modulation appeared to be allosteric and differs from that of other BK pore blockers (paxilline, peptide toxins, and quaternary ammonium compounds). Together, our results unravel the potential of piperine to inhibit BK channels, providing a new tool to explore mechanisms underlying the effects of regulatory subunits.
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Affiliation(s)
- Aravind Kshatri
- Department of Basic Medical Sciences, Medical School, Universidad de La Laguna, Tenerife, Spain; Instituto de Tecnologias Biomedicas, Universidad de La Laguna, Tenerife, Spain
| | - Belinda Rivero-Pérez
- Department of Basic Medical Sciences, Medical School, Universidad de La Laguna, Tenerife, Spain; Instituto de Tecnologias Biomedicas, Universidad de La Laguna, Tenerife, Spain
| | - Teresa Giraldez
- Department of Basic Medical Sciences, Medical School, Universidad de La Laguna, Tenerife, Spain; Instituto de Tecnologias Biomedicas, Universidad de La Laguna, Tenerife, Spain.
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2
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Martínez Lázaro R, Bartolome-Martin D, Giraldez T. Role of the NMDAR-GluN2B subunits in the function of supramolecular NMDAR-BK channel complexes. Biophys J 2023; 122:387a. [PMID: 36783965 DOI: 10.1016/j.bpj.2022.11.2119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023] Open
Affiliation(s)
- Rebeca Martínez Lázaro
- Department of Basic Medical Sciences, University of La Laguna, San Cristobal de La Laguna, Spain
| | | | - Teresa Giraldez
- Department of Basic Medical Sciences, University of La Laguna, San Cristobal de La Laguna, Spain
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3
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Jesus Gonzalez Hernandez A, Rivero-Perez B, Bartolome-Martin D, de la Rosa DA, Plested AJ, Giraldez T. Ca2+-dependent photocrosslinking in the BK channel intracellular intersubunit interfaces. Biophys J 2022. [DOI: 10.1016/j.bpj.2021.11.289] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022] Open
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4
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Martin-Batista E, Manville RW, Rivero-Pérez B, Bartolomé-Martín D, Alvarez de la Rosa D, Abbott GW, Giraldez T. Activation of SGK1.1 Upregulates the M-current in the Presence of Epilepsy Mutations. Front Mol Neurosci 2021; 14:798261. [PMID: 34899186 PMCID: PMC8662703 DOI: 10.3389/fnmol.2021.798261] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Accepted: 11/01/2021] [Indexed: 11/13/2022] Open
Abstract
In the central nervous system, the M-current plays a critical role in regulating subthreshold electrical excitability of neurons, determining their firing properties and responsiveness to synaptic input. The M-channel is mainly formed by subunits Kv7.2 and Kv7.3 that co-assemble to form a heterotetrametric channel. Mutations in Kv7.2 and Kv7.3 are associated with hyperexcitability phenotypes including benign familial neonatal epilepsy (BFNE) and neonatal epileptic encephalopathy (NEE). SGK1.1, the neuronal isoform of the serum and glucocorticoids-regulated kinase 1 (SGK1), increases M-current density in neurons, leading to reduced excitability and protection against seizures. Herein, using two-electrode voltage clamp on Xenopus laevis oocytes, we demonstrate that SGK1.1 selectively activates heteromeric Kv7 subunit combinations underlying the M-current. Importantly, activated SGK1.1 increases M-channel activity in the presence of two different epilepsy mutations found in Kv7.2, R207W and A306T. In addition, proximity ligation assays in the N2a cell line allowed us to address the effect of these mutations on Kv7-SGK1.1-Nedd4 molecular associations, a proposed pathway underlying augmentation of M-channel activity by SGK1.1.
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Affiliation(s)
- Elva Martin-Batista
- Departamento de Ciencias Medicas Basicas and Instituto de Tecnologias Biomedicas, Universidad de La Laguna, San Cristóbal de La Laguna, Spain
| | - Rían W Manville
- Bioelectricity Laboratory, Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, Irvine, CA, United States
| | - Belinda Rivero-Pérez
- Departamento de Ciencias Medicas Basicas and Instituto de Tecnologias Biomedicas, Universidad de La Laguna, San Cristóbal de La Laguna, Spain
| | - David Bartolomé-Martín
- Departamento de Ciencias Medicas Basicas and Instituto de Tecnologias Biomedicas, Universidad de La Laguna, San Cristóbal de La Laguna, Spain
| | - Diego Alvarez de la Rosa
- Departamento de Ciencias Medicas Basicas and Instituto de Tecnologias Biomedicas, Universidad de La Laguna, San Cristóbal de La Laguna, Spain
| | - Geoffrey W Abbott
- Bioelectricity Laboratory, Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, Irvine, CA, United States
| | - Teresa Giraldez
- Departamento de Ciencias Medicas Basicas and Instituto de Tecnologias Biomedicas, Universidad de La Laguna, San Cristóbal de La Laguna, Spain
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5
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Kshatri A, Cerrada A, Gimeno R, Bartolomé-Martín D, Rojas P, Giraldez T. Differential regulation of BK channels by fragile X mental retardation protein. J Gen Physiol 2021; 152:151651. [PMID: 32275741 PMCID: PMC7266151 DOI: 10.1085/jgp.201912502] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Accepted: 03/12/2020] [Indexed: 01/28/2023] Open
Abstract
Fragile X mental retardation protein (FMRP) is an RNA-binding protein prominently expressed in neurons. Missense mutations or complete loss of FMRP can potentially lead to fragile X syndrome, a common form of inherited intellectual disability. In addition to RNA regulation, FMRP was also proposed to modulate neuronal function by direct interaction with the large conductance Ca2+- and voltage-activated potassium channel (BK) β4 regulatory subunits (BKβ4). However, the molecular mechanisms underlying FMRP regulation of BK channels were not studied in detail. We have used electrophysiology and super-resolution stochastic optical reconstruction microscopy (STORM) to characterize the effects of FMRP on pore-forming BKα subunits, as well as the association with regulatory subunits BKβ4. Our data indicate that, in the absence of coexpressed β4, FMRP alters the steady-state properties of BKα channels by decreasing channel activation and deactivation rates. Analysis using the Horrigan-Aldrich model revealed alterations in the parameters associated with channel opening (L0) and voltage sensor activation (J0). Interestingly, FMRP also altered the biophysical properties of BKαβ4 channels favoring channel opening, although not as dramatically as BKα. STORM experiments revealed clustered multi-protein complexes, consistent with FMRP interacting not only to BKαβ4 but also to BKα. Lastly, we found that a partial loss-of-function mutation in FMRP (R138Q) counteracts many of its functional effects on BKα and BKαβ4 channels. In summary, our data show that FMRP modulates the function of both BKα and BKαβ4 channels.
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Affiliation(s)
- Aravind Kshatri
- Departamento de Ciencias Medicas Basicas-Fisiologia, Universidad de La Laguna, Tenerife, Spain.,Instituto de Tecnologías Biomedicas, Universidad de La Laguna, Tenerife, Spain
| | - Alejandro Cerrada
- Departamento de Ciencias Medicas Basicas-Fisiologia, Universidad de La Laguna, Tenerife, Spain.,Instituto de Tecnologías Biomedicas, Universidad de La Laguna, Tenerife, Spain
| | - Roger Gimeno
- Departamento de Ciencias Medicas Basicas-Fisiologia, Universidad de La Laguna, Tenerife, Spain.,Instituto de Tecnologías Biomedicas, Universidad de La Laguna, Tenerife, Spain
| | - David Bartolomé-Martín
- Departamento de Ciencias Medicas Basicas-Fisiologia, Universidad de La Laguna, Tenerife, Spain.,Instituto de Tecnologías Biomedicas, Universidad de La Laguna, Tenerife, Spain
| | - Patricio Rojas
- Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile
| | - Teresa Giraldez
- Departamento de Ciencias Medicas Basicas-Fisiologia, Universidad de La Laguna, Tenerife, Spain.,Instituto de Tecnologías Biomedicas, Universidad de La Laguna, Tenerife, Spain
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6
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Martin-Batista E, Maglio LE, Armas-Capote N, Hernández G, Alvarez de la Rosa D, Giraldez T. SGK1.1 limits brain damage after status epilepticus through M current-dependent and independent mechanisms. Neurobiol Dis 2021; 153:105317. [PMID: 33639207 DOI: 10.1016/j.nbd.2021.105317] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Revised: 02/04/2021] [Accepted: 02/22/2021] [Indexed: 10/22/2022] Open
Abstract
Epilepsy is a neurological condition associated to significant brain damage produced by status epilepticus (SE) including neurodegeneration, gliosis and ectopic neurogenesis. Reduction of these processes constitutes a useful strategy to improve recovery and ameliorate negative outcomes after an initial insult. SGK1.1, the neuronal isoform of the serum and glucocorticoids-regulated kinase 1 (SGK1), has been shown to increase M-current density in neurons, leading to reduced excitability and protection against seizures. For this study, we used 4-5 months old male transgenic C57BL/6 J and FVB/NJ mice expressing near physiological levels of a constitutively active form of the kinase controlled by its endogenous promoter. Here we show that SGK1.1 activation potently reduces levels of neuronal death (assessed using Fluoro-Jade C staining) and reactive glial activation (reported by GFAP and Iba-1 markers) in limbic regions and cortex, 72 h after SE induced by kainate, even in the context of high seizure activity. This neuroprotective effect is not exclusively through M-current activation but is also directly linked to decreased apoptosis levels assessed by TUNEL assays and quantification of Bim and Bcl-xL by western blot of hippocampal protein extracts. Our results demonstrate that this newly described antiapoptotic role of SGK1.1 activation acts synergistically with the regulation of cellular excitability, resulting in a significant reduction of SE-induced brain damage in areas relevant to epileptogenesis.
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Affiliation(s)
- Elva Martin-Batista
- Departamento de Ciencias Médicas Básicas, Facultad de Medicina, Universidad de La Laguna, Campus de Ciencias de la Salud sn, 38200 San Cristobal de La Laguna, Spain; Instituto de Tecnologías Biomédicas (ITB), Campus de Ciencias de la Salud sn, 38071 San Cristobal de La Laguna, Spain.
| | - Laura E Maglio
- Departamento de Ciencias Médicas Básicas, Facultad de Medicina, Universidad de La Laguna, Campus de Ciencias de la Salud sn, 38200 San Cristobal de La Laguna, Spain; Instituto de Tecnologías Biomédicas (ITB), Campus de Ciencias de la Salud sn, 38071 San Cristobal de La Laguna, Spain.
| | - Natalia Armas-Capote
- Departamento de Ciencias Médicas Básicas, Facultad de Medicina, Universidad de La Laguna, Campus de Ciencias de la Salud sn, 38200 San Cristobal de La Laguna, Spain; Instituto de Tecnologías Biomédicas (ITB), Campus de Ciencias de la Salud sn, 38071 San Cristobal de La Laguna, Spain.
| | - Guadalberto Hernández
- Departamento de Ciencias Médicas Básicas, Facultad de Medicina, Universidad de La Laguna, Campus de Ciencias de la Salud sn, 38200 San Cristobal de La Laguna, Spain; Instituto de Tecnologías Biomédicas (ITB), Campus de Ciencias de la Salud sn, 38071 San Cristobal de La Laguna, Spain.
| | - Diego Alvarez de la Rosa
- Departamento de Ciencias Médicas Básicas, Facultad de Medicina, Universidad de La Laguna, Campus de Ciencias de la Salud sn, 38200 San Cristobal de La Laguna, Spain; Instituto de Tecnologías Biomédicas (ITB), Campus de Ciencias de la Salud sn, 38071 San Cristobal de La Laguna, Spain.
| | - Teresa Giraldez
- Departamento de Ciencias Médicas Básicas, Facultad de Medicina, Universidad de La Laguna, Campus de Ciencias de la Salud sn, 38200 San Cristobal de La Laguna, Spain; Instituto de Tecnologías Biomédicas (ITB), Campus de Ciencias de la Salud sn, 38071 San Cristobal de La Laguna, Spain.
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7
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Giraldez T. Insights into the Function of BK-Ca Multi-Channel Complexes. Biophys J 2021. [DOI: 10.1016/j.bpj.2020.11.329] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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8
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Bartolome-Martin D, Gimeno R, Rivero-Perez B, Cerrada A, Gonzalez-Hernandez AJ, de la Rosa DA, Giraldez T. Development and Optimization of Calcium Fluorescent Sensors Based on BK Ion Channels. Biophys J 2021. [DOI: 10.1016/j.bpj.2020.11.1581] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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9
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Martínez Lázaro R, Bartolome-Martin D, Gomez R, Giraldez T. Role of the NMDAR-NR2B Subunit in the Function of Supramolecular NMDAR-BK Complexes. Biophys J 2021. [DOI: 10.1016/j.bpj.2020.11.1580] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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10
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Cazaña-Pérez V, Cidad P, Navarro-González JF, Rojo-Mencía J, Jaisser F, López-López JR, Alvarez de la Rosa D, Giraldez T, Pérez-García M. Kv1.3 Channel Inhibition Limits Uremia-Induced Calcification in Mouse and Human Vascular Smooth Muscle. Function (Oxf) 2020; 2:zqaa036. [PMID: 35330975 PMCID: PMC8788811 DOI: 10.1093/function/zqaa036] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Revised: 11/30/2020] [Accepted: 12/03/2020] [Indexed: 01/06/2023] Open
Abstract
Chronic kidney disease (CKD) significantly increases cardiovascular risk. In advanced CKD stages, accumulation of toxic circulating metabolites and mineral metabolism alterations triggers vascular calcification, characterized by vascular smooth muscle cell (VSMC) transdifferentiation and loss of the contractile phenotype. Phenotypic modulation of VSMC occurs with significant changes in gene expression. Even though ion channels are an integral component of VSMC function, the effects of uremia on ion channel remodeling has not been explored. We used an in vitro model of uremia-induced calcification of human aorta smooth muscle cells (HASMCs) to study the expression of 92 ion channel subunit genes. Uremic serum-induced extensive remodeling of ion channel expression consistent with loss of excitability but different from the one previously associated with transition from contractile to proliferative phenotypes. Among the ion channels tested, we found increased abundance and activity of voltage-dependent K+ channel Kv1.3. Enhanced Kv1.3 expression was also detected in aorta from a mouse model of CKD. Pharmacological inhibition or genetic ablation of Kv1.3 decreased the amount of calcium phosphate deposition induced by uremia, supporting an important role for this channel on uremia-induced VSMC calcification.
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Affiliation(s)
- Violeta Cazaña-Pérez
- Departamento de Ciencias Médicas Básicas (Fisiología), Instituto de Tecnologías Biomédicas, Universidad de La Laguna, Spain
- Unidad de Investigación y Servicio de Nefrología, Hospital Universitario Nuestra Señora de Candelaria, Tenerife, Spain
| | - Pilar Cidad
- Departamento de Bioquímica y Biología Molecular y Fisiología e Instituto de Biología y Genética Molecular (IBGM), Universidad de Valladolid y Consejo Superior de Investigaciones Científicas (CSIC), Valladolid, Spain
| | - Juan F Navarro-González
- Unidad de Investigación y Servicio de Nefrología, Hospital Universitario Nuestra Señora de Candelaria, Tenerife, Spain
| | - Jorge Rojo-Mencía
- Departamento de Bioquímica y Biología Molecular y Fisiología e Instituto de Biología y Genética Molecular (IBGM), Universidad de Valladolid y Consejo Superior de Investigaciones Científicas (CSIC), Valladolid, Spain
| | - Frederic Jaisser
- Unité Mixte de Recherche Scientifique 1138, Team 1, Institut National de la Santé et de la Recherche Médicale, Centre de Recherche des Cordeliers, La Laguna, Paris, France
| | - José R López-López
- Departamento de Bioquímica y Biología Molecular y Fisiología e Instituto de Biología y Genética Molecular (IBGM), Universidad de Valladolid y Consejo Superior de Investigaciones Científicas (CSIC), Valladolid, Spain
| | - Diego Alvarez de la Rosa
- Departamento de Ciencias Médicas Básicas (Fisiología), Instituto de Tecnologías Biomédicas, Universidad de La Laguna, Spain
| | - Teresa Giraldez
- Departamento de Ciencias Médicas Básicas (Fisiología), Instituto de Tecnologías Biomédicas, Universidad de La Laguna, Spain
| | - Maria Teresa Pérez-García
- Departamento de Bioquímica y Biología Molecular y Fisiología e Instituto de Biología y Genética Molecular (IBGM), Universidad de Valladolid y Consejo Superior de Investigaciones Científicas (CSIC), Valladolid, Spain
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Kshatri A, Cerrada A, Gimeno R, Bartolomé-Martín D, Rojas P, Giraldez T. Correction: Differential regulation of BK channels by fragile X mental retardation protein. J Gen Physiol 2020; 152:151809. [PMID: 32442240 PMCID: PMC7957326 DOI: 10.1085/jgp.20191250205042020c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
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12
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Kshatri AS, Giraldez T. Reversible Block of BK Channels by Piperine. Biophys J 2020. [DOI: 10.1016/j.bpj.2019.11.1530] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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13
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Armas-Capote N, Maglio LE, Pérez-Atencio L, Martin-Batista E, Reboreda A, Barios JA, Hernandez G, Alvarez de la Rosa D, Lamas JA, Barrio LC, Giraldez T. SGK1.1 Reduces Kainic Acid-Induced Seizure Severity and Leads to Rapid Termination of Seizures. Cereb Cortex 2019; 30:3184-3197. [DOI: 10.1093/cercor/bhz302] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Revised: 10/19/2019] [Accepted: 11/08/2019] [Indexed: 12/17/2022] Open
Abstract
Abstract
Approaches to control epilepsy, one of the most important idiopathic brain disorders, are of great importance for public health. We have previously shown that in sympathetic neurons the neuronal isoform of the serum and glucocorticoid-regulated kinase (SGK1.1) increases the M-current, a well-known target for seizure control. The effect of SGK1.1 activation on kainate-induced seizures and neuronal excitability was studied in transgenic mice that express a permanently active form of the kinase, using electroencephalogram recordings and electrophysiological measurements in hippocampal brain slices. Our results demonstrate that SGK1.1 activation leads to reduced seizure severity and lower mortality rates following status epilepticus, in an M-current–dependent manner. EEG is characterized by reduced number, shorter duration, and early termination of kainate-induced seizures in the hippocampus and cortex. Hippocampal neurons show decreased excitability associated to increased M-current, without altering basal synaptic transmission or other neuronal properties. Altogether, our results reveal a novel and selective anticonvulsant pathway that promptly terminates seizures, suggesting that SGK1.1 activation can be a potent factor to secure the brain against permanent neuronal damage associated to epilepsy.
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Affiliation(s)
- Natalia Armas-Capote
- Departamento de Ciencias Medicas Basicas-Fisiologia and Instituto de Tecnologías Biomedicas (ITB), Universidad de La Laguna, Tenerife, 38071 Spain
| | - Laura E Maglio
- Departamento de Ciencias Medicas Basicas-Fisiologia and Instituto de Tecnologías Biomedicas (ITB), Universidad de La Laguna, Tenerife, 38071 Spain
| | - Leonel Pérez-Atencio
- Unidad de Neurologia Experimental, Hospital Ramon y Cajal-IRYCIS, Madrid, 28034 Spain
| | - Elva Martin-Batista
- Departamento de Ciencias Medicas Basicas-Fisiologia and Instituto de Tecnologías Biomedicas (ITB), Universidad de La Laguna, Tenerife, 38071 Spain
| | - Antonio Reboreda
- Department of Functional Biology and Health Sciences, Faculty of Biology-CINBIO-IBIV, University of Vigo, Vigo, 36310 Spain
| | - Juan A Barios
- Systems Engineering and Automation Department, Miguel Hernandez University, Elche, 03202 Spain
| | - Guadalberto Hernandez
- Departamento de Ciencias Medicas Basicas-Fisiologia and Instituto de Tecnologías Biomedicas (ITB), Universidad de La Laguna, Tenerife, 38071 Spain
| | - Diego Alvarez de la Rosa
- Departamento de Ciencias Medicas Basicas-Fisiologia and Instituto de Tecnologías Biomedicas (ITB), Universidad de La Laguna, Tenerife, 38071 Spain
| | - José Antonio Lamas
- Department of Functional Biology and Health Sciences, Faculty of Biology-CINBIO-IBIV, University of Vigo, Vigo, 36310 Spain
| | - Luis C Barrio
- Unidad de Neurologia Experimental, Hospital Ramon y Cajal-IRYCIS, Madrid, 28034 Spain
| | - Teresa Giraldez
- Departamento de Ciencias Medicas Basicas-Fisiologia and Instituto de Tecnologías Biomedicas (ITB), Universidad de La Laguna, Tenerife, 38071 Spain
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14
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Gómez R, Maglio LE, Gonzalez-Hernandez AJ, Rivero-Perez B, Giraldez T. Role of NMDAR-BK Complexes in the Integration of Synaptic Inputs of Barrel Cortex Pyramidal Neurons. Biophys J 2019. [DOI: 10.1016/j.bpj.2018.11.240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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15
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Miranda P, Holmgren M, Giraldez T. Voltage-dependent dynamics of the BK channel cytosolic gating ring are coupled to the membrane-embedded voltage sensor. eLife 2018; 7:40664. [PMID: 30526860 PMCID: PMC6301790 DOI: 10.7554/elife.40664] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Accepted: 12/11/2018] [Indexed: 12/21/2022] Open
Abstract
In humans, large conductance voltage- and calcium-dependent potassium (BK) channels are regulated allosterically by transmembrane voltage and intracellular Ca2+. Divalent cation binding sites reside within the gating ring formed by two Regulator of Conductance of Potassium (RCK) domains per subunit. Using patch-clamp fluorometry, we show that Ca2+ binding to the RCK1 domain triggers gating ring rearrangements that depend on transmembrane voltage. Because the gating ring is outside the electric field, this voltage sensitivity must originate from coupling to the voltage-dependent channel opening, the voltage sensor or both. Here we demonstrate that alterations of the voltage sensor, either by mutagenesis or regulation by auxiliary subunits, are paralleled by changes in the voltage dependence of the gating ring movements, whereas modifications of the relative open probability are not. These results strongly suggest that conformational changes of RCK1 domains are specifically coupled to the voltage sensor function during allosteric modulation of BK channels.
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Affiliation(s)
- Pablo Miranda
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, United States
| | - Miguel Holmgren
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, United States
| | - Teresa Giraldez
- Departamento de Ciencias Medicas Basicas, Universidad de La Laguna, San Cristóbal de La Laguna, Spain.,Instituto de Tecnologias Biomedicas, Universidad de La Laguna, San Cristóbal de La Laguna, Spain
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16
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Kshatri AS, Gonzalez-Hernandez A, Giraldez T. Physiological Roles and Therapeutic Potential of Ca 2+ Activated Potassium Channels in the Nervous System. Front Mol Neurosci 2018; 11:258. [PMID: 30104956 PMCID: PMC6077210 DOI: 10.3389/fnmol.2018.00258] [Citation(s) in RCA: 63] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Accepted: 07/06/2018] [Indexed: 12/21/2022] Open
Abstract
Within the potassium ion channel family, calcium activated potassium (KCa) channels are unique in their ability to couple intracellular Ca2+ signals to membrane potential variations. KCa channels are diversely distributed throughout the central nervous system and play fundamental roles ranging from regulating neuronal excitability to controlling neurotransmitter release. The physiological versatility of KCa channels is enhanced by alternative splicing and co-assembly with auxiliary subunits, leading to fundamental differences in distribution, subunit composition and pharmacological profiles. Thus, understanding specific KCa channels’ mechanisms in neuronal function is challenging. Based on their single channel conductance, KCa channels are divided into three subtypes: small (SK, 4–14 pS), intermediate (IK, 32–39 pS) and big potassium (BK, 200–300 pS) channels. This review describes the biophysical characteristics of these KCa channels, as well as their physiological roles and pathological implications. In addition, we also discuss the current pharmacological strategies and challenges to target KCa channels for the treatment of various neurological and psychiatric disorders.
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Affiliation(s)
- Aravind S Kshatri
- Department of Basic Medical Sciences, Medical School, Universidad de La Laguna, Tenerife, Spain.,Instituto de Tecnologias Biomedicas, Universidad de La Laguna, Tenerife, Spain
| | - Alberto Gonzalez-Hernandez
- Department of Basic Medical Sciences, Medical School, Universidad de La Laguna, Tenerife, Spain.,Instituto de Tecnologias Biomedicas, Universidad de La Laguna, Tenerife, Spain
| | - Teresa Giraldez
- Department of Basic Medical Sciences, Medical School, Universidad de La Laguna, Tenerife, Spain.,Instituto de Tecnologias Biomedicas, Universidad de La Laguna, Tenerife, Spain
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Rosa DA, Cazaña‐Perez V, Giraldez T, Navarro‐Gonzalez JF, Kusche‐Virhog K. Mineralocortidoid Receptor Mediates Uremic Serum‐Induced Increase in Endothelial Cell Dysfunction. FASEB J 2018. [DOI: 10.1096/fasebj.2018.32.1_supplement.904.8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | | | | | - Juan F. Navarro‐Gonzalez
- Unidad de InvestigaciónHospital Universitario Nuestra Señora de CandelariaSanta Cruz de TenerifeSpain
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18
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Cazaña-Pérez V, Cidad P, Donate-Correa J, Martín-Núñez E, López-López JR, Pérez-García MT, Giraldez T, Navarro-González JF, Alvarez de la Rosa D. Phenotypic Modulation of Cultured Primary Human Aortic Vascular Smooth Muscle Cells by Uremic Serum. Front Physiol 2018; 9:89. [PMID: 29483881 PMCID: PMC5816230 DOI: 10.3389/fphys.2018.00089] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Accepted: 01/26/2018] [Indexed: 12/16/2022] Open
Abstract
Patients with chronic kidney disease (CKD) have a markedly increased incidence of cardiovascular disease (CVD). The high concentration of circulating uremic toxins and alterations in mineral metabolism and hormone levels produce vascular wall remodeling and significant vascular damage. Medial calcification is an early vascular event in CKD patients and is associated to apoptosis or necrosis and trans-differentiation of vascular smooth muscle cells (VSMC) to an osteogenic phenotype. VSMC obtained from bovine or rat aorta and cultured in the presence of increased inorganic phosphate (Pi) have been extensively used to study these processes. In this study we used human aortic VSMC primary cultures to compare the effects of increased Pi to treatment with serum obtained from uremic patients. Uremic serum induced calcification, trans-differentiation and phenotypic remodeling even with normal Pi levels. In spite of similar calcification kinetics, there were fundamental differences in osteochondrogenic marker expression and alkaline phosphatase induction between Pi and uremic serum-treated cells. Moreover, high Pi induced a dramatic decrease in cell viability, while uremic serum preserved it. In summary, our data suggests that primary cultures of human VSMC treated with serum from uremic patients provides a more informative model for the study of vascular calcification secondary to CKD.
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Affiliation(s)
- Violeta Cazaña-Pérez
- Departamento de Ciencias Médicas Básicas (Fisiología), Instituto de Tecnologías Biomédicas and Centro de Investigaciones Biomédicas de Canarias, Universidad de La Laguna, Tenerife, Spain.,Unidad de Investigación, Hospital Universitario Nuestra Señora de Candelaria, Tenerife, Spain
| | - Pilar Cidad
- Departamento de Bioquímica y Biología Molecular y Fisiología e Instituto de Biología y Genética Molecular (IBGM), Universidad de Valladolid y Consejo Superior de Investigaciones Científicas (CSIC), Valladolid, Spain
| | - Javier Donate-Correa
- Unidad de Investigación, Hospital Universitario Nuestra Señora de Candelaria, Tenerife, Spain
| | - Ernesto Martín-Núñez
- Unidad de Investigación, Hospital Universitario Nuestra Señora de Candelaria, Tenerife, Spain
| | - José R López-López
- Departamento de Bioquímica y Biología Molecular y Fisiología e Instituto de Biología y Genética Molecular (IBGM), Universidad de Valladolid y Consejo Superior de Investigaciones Científicas (CSIC), Valladolid, Spain
| | - M Teresa Pérez-García
- Departamento de Bioquímica y Biología Molecular y Fisiología e Instituto de Biología y Genética Molecular (IBGM), Universidad de Valladolid y Consejo Superior de Investigaciones Científicas (CSIC), Valladolid, Spain
| | - Teresa Giraldez
- Departamento de Ciencias Médicas Básicas (Fisiología), Instituto de Tecnologías Biomédicas and Centro de Investigaciones Biomédicas de Canarias, Universidad de La Laguna, Tenerife, Spain
| | - Juan F Navarro-González
- Unidad de Investigación, Hospital Universitario Nuestra Señora de Candelaria, Tenerife, Spain
| | - Diego Alvarez de la Rosa
- Departamento de Ciencias Médicas Básicas (Fisiología), Instituto de Tecnologías Biomédicas and Centro de Investigaciones Biomédicas de Canarias, Universidad de La Laguna, Tenerife, Spain
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Giraldez T. Molecular Rearrangements Underlying Function of Large Conductance Calcium- and Voltage-Regulated Potassium Channels. Biophys J 2018. [DOI: 10.1016/j.bpj.2017.11.246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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20
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Giraldez T. The GoSlo family of BK channel activators: A no-go for γ subunits? Channels (Austin) 2017; 11:89-90. [PMID: 27960620 DOI: 10.1080/19336950.2016.1263136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Affiliation(s)
- Teresa Giraldez
- a Department of Basic Medical Sciences , Institute of Biomedical Technologies, Center for Biomedical Research of the Canary Islands (CIBICAN) &Universidad de La Laguna , Tenerife , Spain
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Abstract
A timely review of the structural basis of Ca2+-activated K+ channel modulation by regulator of conduction of K+ (RCK) domains Regulator of conduction of K+ (RCK) domains are ubiquitous regulators of channel and transporter activity in prokaryotes and eukaryotes. In humans, RCK domains form an integral component of large-conductance calcium-activated K channels (BK channels), key modulators of nerve, muscle, and endocrine cell function. In this review, we explore how the study of RCK domains in bacterial and human channels has contributed to our understanding of the structural basis of channel function. This knowledge will be critical in identifying mechanisms that underlie BK channelopathies that lead to epilepsy and other diseases, as well as regions of the channel that might be successfully targeted to treat such diseases.
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Affiliation(s)
- Teresa Giraldez
- Department of Basic Medical Sciences, Institute of Biomedical Technologies and Centre for Biomedical Research of the Canary Islands, Universidad de La Laguna, La Laguna 38071, Spain
| | - Brad S Rothberg
- Department of Medical Genetics and Molecular Biochemistry, Temple University Lewis Katz School of Medicine, Philadelphia, PA 19140
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22
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Jiménez-Canino R, Lorenzo-Díaz F, Jaisser F, Farman N, Giraldez T, Alvarez de la Rosa D. Histone Deacetylase 6-Controlled Hsp90 Acetylation Significantly Alters Mineralocorticoid Receptor Subcellular Dynamics But Not its Transcriptional Activity. Endocrinology 2016; 157:2515-32. [PMID: 27100623 DOI: 10.1210/en.2015-2055] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The mineralocorticoid receptor (MR) is a member of the nuclear receptor superfamily that transduces the biological effects of corticosteroids. Its best-characterized role is to enhance transepithelial sodium reabsorption in response to increased aldosterone levels. In addition, MR participates in other aldosterone- or glucocorticoid-controlled processes such as cardiovascular homeostasis, adipocyte differentiation or neurogenesis, and regulation of neuronal activity in the hippocampus. Like other steroid receptors, MR forms cytosolic heterocomplexes with heat shock protein (Hsp) 90), Hsp70, and other proteins such as immunophilins. Interaction with Hsp90 is thought to maintain MR in a ligand-binding competent conformation and to regulate ligand-dependent and -independent nucleocytoplasmatic shuttling. It has previously been shown that acetylation of residue K295 in Hsp90 regulates its interaction with the androgen receptor and glucocorticoid receptor (GR). In this work we hypothesized that Hsp90 acetylation provides a regulatory step to modulate MR cellular dynamics and activity. We used Hsp90 acetylation mimic mutant K295Q or nonacetylatable mutant K295R to examine whether MR nucleocytoplasmatic shuttling and gene transactivation are affected. Furthermore, we manipulated endogenous Hsp90 acetylation levels by controlling expression or activity of histone deacetylase 6 (HDAC6), the enzyme responsible for deacetylation of Hsp90-K295. Our data demonstrates that HDAC6-mediated Hsp90 acetylation regulates MR cellular dynamics but it does not alter its function. This stands in contrast with the down-regulation of GR by HDAC6, suggesting that Hsp90 acetylation may play a role in balancing relative MR and GR activity when both factors are co-expressed in the same cell.
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Affiliation(s)
- Rubén Jiménez-Canino
- Department of Physiology (R.J.-C., F.L.-D., T.G., D.A.d.l.R.), Institute of Biomedical Technologies and Center for Biomedical Research of the Canary Islands, University of La Laguna, Tenerife 38071, Spain; and INSERM UMRS 1138 (N.J., N.F.), Team 1, Centre de Recherche des Cordeliers, Université Pierre et Marie Curie, Paris 75006, France
| | - Fabián Lorenzo-Díaz
- Department of Physiology (R.J.-C., F.L.-D., T.G., D.A.d.l.R.), Institute of Biomedical Technologies and Center for Biomedical Research of the Canary Islands, University of La Laguna, Tenerife 38071, Spain; and INSERM UMRS 1138 (N.J., N.F.), Team 1, Centre de Recherche des Cordeliers, Université Pierre et Marie Curie, Paris 75006, France
| | - Frederic Jaisser
- Department of Physiology (R.J.-C., F.L.-D., T.G., D.A.d.l.R.), Institute of Biomedical Technologies and Center for Biomedical Research of the Canary Islands, University of La Laguna, Tenerife 38071, Spain; and INSERM UMRS 1138 (N.J., N.F.), Team 1, Centre de Recherche des Cordeliers, Université Pierre et Marie Curie, Paris 75006, France
| | - Nicolette Farman
- Department of Physiology (R.J.-C., F.L.-D., T.G., D.A.d.l.R.), Institute of Biomedical Technologies and Center for Biomedical Research of the Canary Islands, University of La Laguna, Tenerife 38071, Spain; and INSERM UMRS 1138 (N.J., N.F.), Team 1, Centre de Recherche des Cordeliers, Université Pierre et Marie Curie, Paris 75006, France
| | - Teresa Giraldez
- Department of Physiology (R.J.-C., F.L.-D., T.G., D.A.d.l.R.), Institute of Biomedical Technologies and Center for Biomedical Research of the Canary Islands, University of La Laguna, Tenerife 38071, Spain; and INSERM UMRS 1138 (N.J., N.F.), Team 1, Centre de Recherche des Cordeliers, Université Pierre et Marie Curie, Paris 75006, France
| | - Diego Alvarez de la Rosa
- Department of Physiology (R.J.-C., F.L.-D., T.G., D.A.d.l.R.), Institute of Biomedical Technologies and Center for Biomedical Research of the Canary Islands, University of La Laguna, Tenerife 38071, Spain; and INSERM UMRS 1138 (N.J., N.F.), Team 1, Centre de Recherche des Cordeliers, Université Pierre et Marie Curie, Paris 75006, France
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Miranda P, Giraldez T, Holmgren M. Selective Cation Binding to the Gating-Ring Triggers Independent RCK Motions in the BK Channel. Biophys J 2016. [DOI: 10.1016/j.bpj.2015.11.1041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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24
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Cazaña‐Perez V, Giraldez T, Navarro‐Gonzalez J, Alvarez de la Rosa D. The role of Mineralocorticoid Receptor on Human Aortic Endothelial Ion Channel Expression Profile in Chronic Kidney Disease. FASEB J 2015. [DOI: 10.1096/fasebj.29.1_supplement.844.19] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Violeta Cazaña‐Perez
- Department of Physiology and Center for Biomedical Research of the Canary Islands (CIBICAN) University of La LagunaLa LagunaTenerifeSpain
| | - Teresa Giraldez
- Department of Physiology and Center for Biomedical Research of the Canary Islands (CIBICAN) University of La LagunaLa LagunaTenerifeSpain
| | - Juan Navarro‐Gonzalez
- Research Unit and Nephrology Service University Hospital Nuestra Señora de CandelariaSanta Cruz de TenerifeSpain
| | - Diego Alvarez de la Rosa
- Department of Physiology and Center for Biomedical Research of the Canary Islands (CIBICAN) University of La LagunaLa LagunaTenerifeSpain
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25
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Jimenez‐Canino R, Fernandes M, Martin‐Martinez M, Gonzalez‐Muñiz R, Giraldez T, Alvarez de la Rosa D. Phosphorylation of Mineralocorticoid Receptor at Residue S839 Impairs Aldosterone‐dependent Gene Transactivation Coupling in a Dominant Negative Manner. FASEB J 2015. [DOI: 10.1096/fasebj.29.1_supplement.974.12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Ruben Jimenez‐Canino
- Department of Physiology and Center for Biomedical Research of the Canary Islands (CIBICAN) University of La LagunaLa LagunaTenerifeSpain
| | - Miguel Fernandes
- Instituto Universitario de Bio‐Orgánica 'Antonio González' (IUBO‐AG) and Center for Biomedical Research of the Canary Islands (CIBICAN) University of La LagunaLa LagunaTenerifeSpain
| | | | | | - Teresa Giraldez
- Department of Physiology and Center for Biomedical Research of the Canary Islands (CIBICAN) University of La LagunaLa LagunaTenerifeSpain
| | - Diego Alvarez de la Rosa
- Department of Physiology and Center for Biomedical Research of the Canary Islands (CIBICAN) University of La LagunaLa LagunaTenerifeSpain
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26
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Gonzalez‐Montelongo R, Alvarez de la Rosa D, Giraldez T. Epithelial Sodium Channel (ENaC) Tagged with Bungarotoxin Binding Site to Study Channel Plasma Membrane Expression and Trafficking. FASEB J 2015. [DOI: 10.1096/fasebj.29.1_supplement.969.18] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Rafaela Gonzalez‐Montelongo
- Department of Physiology and Center for Biomedical Research of the Canary Islands (CIBICAN) University of La LagunaLa LagunaTenerifeSpain
| | - Diego Alvarez de la Rosa
- Department of Physiology and Center for Biomedical Research of the Canary Islands (CIBICAN) University of La LagunaLa LagunaTenerifeSpain
| | - Teresa Giraldez
- Department of Physiology and Center for Biomedical Research of the Canary Islands (CIBICAN) University of La LagunaLa LagunaTenerifeSpain
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Affiliation(s)
- Teresa Giraldez
- Department of Physiology, School of Medicine & Centre for Biomedical Research of the Canary Islands (CIBICAN), University de La Laguna, La Laguna, Santa Cruz de Tenerife, Spain.
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29
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Alvarez de la Rosa D, Jimenez‐Canino R, Lorenzo‐Diaz F, Giraldez T. Hsp90 acetylation regulates mineralocorticoid receptor subcellular dynamics and aldosterone‐induced promoter transactivation (1097.15). FASEB J 2014. [DOI: 10.1096/fasebj.28.1_supplement.1097.15] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Diego Alvarez de la Rosa
- Institute of Biomedical Technologies LA LagunaSpain
- Department of Physiology University of LA LagunaLALagunaSpain
| | | | | | - Teresa Giraldez
- Department of Physiology University of LA LagunaLALagunaSpain
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30
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Giraldez T, Domínguez J, Alvarez de la Rosa D. ENaC in the brain--future perspectives and pharmacological implications. Curr Mol Pharmacol 2013; 6:44-9. [PMID: 23547934 DOI: 10.2174/1874467211306010006] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2012] [Revised: 09/04/2012] [Accepted: 02/24/2013] [Indexed: 11/22/2022]
Abstract
The epithelial sodium channel/degenerin (ENaC/deg) family of ion channels is formed by a large number of genes with variable tissue expression patterns and physiological roles. ENaC is a non-voltage gated, constitutively active channel highly selective for sodium. ENaC is formed by three homologous subunits, α, β and γ, and a fourth subunit (δ) has been found in human and monkeys that can substitute α to form functional channels. The best-characterized role of ENaC is to serve as a rate-limiting step in transepithelial sodium reabsorption in the distal part of the kidney tubule and other tight epithelia. However, ENaC subunits are also found in the peripheral and central nervous system, where their functional roles are only beginning to be understood. In this review, we mainly focus on the putative pathophysiological roles of ENaC channels in the central nervous system and their potential value as drug targets in neurodegenerative disorders and the central control of blood pressure.
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Affiliation(s)
- Teresa Giraldez
- Research Division, University Hospital N.S. Candelaria, Santa Cruz de Tenerife, Spain.
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31
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de la Rosa DA, Navarro-Gonzalez JF, Giraldez T. ENaC Modulators and Renal Disease. Curr Mol Pharmacol 2013; 6:35-43. [DOI: 10.2174/1874467211306010005] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2012] [Revised: 09/03/2012] [Accepted: 02/24/2013] [Indexed: 11/22/2022]
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32
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Rosa DA, Hernandez‐Diaz I, Morales S, Hernandez G, Salido E, Canessa CM, Giraldez T. Heterogeneous nuclear ribonucleoprotein A2/B1 is a novel aldosterone target gene in the rat distal colon epithelium. FASEB J 2013. [DOI: 10.1096/fasebj.27.1_supplement.1148.8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Diego Alvarez Rosa
- PhysiologyUniversidad de La LagunaLa LagunaSpain
- Instituto de Tecnologías Biomédicas, Universidad de La LagunaLa LagunaSpain
| | | | - Silvia Morales
- Servicio de Aparato DigestivoUniversity Hospital NS CandelariaSanta Cruz de TenerifeSpain
| | | | - Eduardo Salido
- Centre for Biomedical Research on Rare DiseasesHospital Universitario de CanariasLa LagunaSpain
| | - Cecilia M Canessa
- Cellular & Molecular PhysiologyYale University School of MedicineNew HavenCT
| | - Teresa Giraldez
- Research DivisionUniversity Hospital NS CandelariaSanta Cruz de TenerifeSpain
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Hernández-Díaz I, Giraldez T, Morales S, Hernandez G, Salido E, Canessa CM, Alvarez de la Rosa D. Heterogeneous nuclear ribonucleoprotein A2/B1 is a tissue-specific aldosterone target gene with prominent induction in the rat distal colon. Am J Physiol Gastrointest Liver Physiol 2013; 304:G122-31. [PMID: 23139218 DOI: 10.1152/ajpgi.00130.2012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The steroid hormone aldosterone enhances transepithelial Na(+) reabsorption in tight epithelia and is crucial to achieve extracellular volume homeostasis and control of blood pressure. One of the main transport pathways regulated by aldosterone involves the epithelial Na(+) channel (ENaC), which constitutes the rate-limiting step of Na(+) reabsorption in parts of the distal nephron and the collecting duct, the distal colon, and sweat and salivary glands. Although these epithelial tissues share the same receptor for aldosterone (mineralocorticoid receptor, MR), and the same transport system (ENaC), it has become clear that the molecular mechanisms involved in the modulation of channel activity are tissue-specific. Recent evidence suggests that aldosterone controls transcription and also translation of ENaC subunits in some cell types. A possible pathway for translational regulation is binding of regulatory proteins to ENaC subunit mRNAs, such as the heterogeneous nuclear ribonucleoprotein A2/B1 (hnRNP A2/B1). In this study, we examined whether hnRNP A2/B1 is an aldosterone-target gene in vivo. Our data show that physiological levels of aldosterone markedly induce hnRNP A2/B1 expression in an early and sustained manner in the late distal colon epithelium but not in other aldosterone-target tissues. The effect depends on MR but not on glucocorticoid receptor activity. We also demonstrate that the genomic region upstream of hnRNP A2/B1 contains aldosterone-responsive elements involved in the control of gene expression. We hypothesize that hnRNP A2/B1 is involved in the tissue-specific regulation of ENaC biosynthesis and may coordinate the response of other genes relevant for transepithelial Na(+) reabsorption by aldosterone.
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Affiliation(s)
- Iván Hernández-Díaz
- Department of Physiology and Instituto de Tecnologías Biomédicas, University of La Laguna, Tenerife, Spain
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Miranda P, Cadaveira-Mosquera A, Gonzalez-Montelongo R, Villarroel A, Antonio Lamas J, de la Rosa DA, Giraldez T. Regulation of the Kv7.2/3 Channels by the Neuronal Serum-and Gluococorticoids-Regulated Kinase 1.1. Biophys J 2013. [DOI: 10.1016/j.bpj.2012.11.1505] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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35
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Aivar P, Fernández-Orth J, Gomis-Perez C, Alberdi A, Alaimo A, Rodríguez MS, Giraldez T, Miranda P, Areso P, Villarroel A. Surface expression and subunit specific control of steady protein levels by the Kv7.2 helix A-B linker. PLoS One 2012; 7:e47263. [PMID: 23115641 PMCID: PMC3480381 DOI: 10.1371/journal.pone.0047263] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2012] [Accepted: 09/11/2012] [Indexed: 02/02/2023] Open
Abstract
Kv7.2 and Kv7.3 are the main components of the neuronal voltage-dependent M-current, which is a subthreshold potassium conductance that exerts an important control on neuronal excitability. Despite their predominantly intracellular distribution, these channels must reach the plasma membrane in order to control neuronal activity. Thus, we analyzed the amino acid sequence of Kv7.2 to identify intrinsic signals that may control its surface expression. Removal of the interlinker connecting helix A and helix B of the intracellular C-terminus produces a large increase in the number of functional channels at the plasma membrane. Moreover, elimination of this linker increased the steady-state amount of protein, which was not associated with a decrease of protein degradation. The magnitude of this increase was inversely correlated with the number of helix A – helix B linkers present in the tetrameric channel assemblies. In contrast to the remarkable effect on the amount of Kv7.2 protein, removal of the Kv7.2 linker had no detectable impact on the steady-state levels of Kv7.3 protein.
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Affiliation(s)
- Paloma Aivar
- Unidad de Biofísica, CSIC, UPV/EHU, Universidad del País Vasco, Barrio Sarriena s/n, Leioa, Spain
| | - Juncal Fernández-Orth
- Unidad de Biofísica, CSIC, UPV/EHU, Universidad del País Vasco, Barrio Sarriena s/n, Leioa, Spain
| | - Carolina Gomis-Perez
- Unidad de Biofísica, CSIC, UPV/EHU, Universidad del País Vasco, Barrio Sarriena s/n, Leioa, Spain
| | - Araitz Alberdi
- Unidad de Biofísica, CSIC, UPV/EHU, Universidad del País Vasco, Barrio Sarriena s/n, Leioa, Spain
| | - Alessandro Alaimo
- Unidad de Biofísica, CSIC, UPV/EHU, Universidad del País Vasco, Barrio Sarriena s/n, Leioa, Spain
| | - Manuel S. Rodríguez
- Proteomics Unit, CIC bioGUNE CIBERehd, Technology Park of Bizkaia, Building, Derio, Spain
| | - Teresa Giraldez
- Unidad de Investigación, Hospital Universitario Ntra Sra Candelaria, Santa Cruz de Tenerife, Spain
| | - Pablo Miranda
- Unidad de Investigación, Hospital Universitario Ntra Sra Candelaria, Santa Cruz de Tenerife, Spain
| | - Pilar Areso
- Dept. Farmacología, UPV/EHU, Universidad del País Vasco, Barrio Sarriena s/n, Leioa, Spain
| | - Alvaro Villarroel
- Unidad de Biofísica, CSIC, UPV/EHU, Universidad del País Vasco, Barrio Sarriena s/n, Leioa, Spain
- * E-mail:
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Aguilar-Sánchez C, Hernández-Díaz I, Lorenzo-Díaz F, Navarro JF, Hughes TE, Giraldez T, Alvarez de la Rosa D. Identification of permissive insertion sites for generating functional fluorescent mineralocorticoid receptors. Endocrinology 2012; 153:3517-25. [PMID: 22621960 DOI: 10.1210/en.2012-1210] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The mineralocorticoid receptor (MR), a member of the nuclear receptor superfamily of transcription factors, is activated by aldosterone and mediates its natriferic action in tight epithelia. MR is also expressed in nonepithelial tissues. Importantly, it mediates the deleterious effects of inappropriately high aldosterone levels in the heart, in which it induces the development of cardiac fibrosis. Antagonism of MR in humans is useful in the treatment of severe cardiac failure and some forms of hypertension. Despite the important pathophysiological and pharmacological role of this receptor, many important questions about its cellular biology and functional roles remain unanswered. A major challenge in the study of MR is the unavailability of fully functional fluorescent derivatives of the receptor. In this study we have created a library of MR mutants with insertions of the yellow fluorescent protein in various internal locations in the receptor using a random-insertion transposon-based technique. Screening of this library using a transactivation assay allowed us to identify several fluorescent constructs that retain functionality. Detailed characterization of one of these construct showed that it induces aldosterone-target genes such as the epithelial Na(+) channel subunits and the serum and glucocorticoid-induced kinase 1 at physiological concentrations of aldosterone to an equal extent than the wild-type receptor. Furthermore, aldosterone affinity, hormone-induced nuclear translocation, DNA binding and regulation of nongenomic pathways are all indistinguishable from the wild-type receptor. This new set of fluorescent MR derivatives provides a useful tool for studying the cell biology of the receptor.
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Affiliation(s)
- Cristina Aguilar-Sánchez
- Department of Physiology and Instituto de Tecnologías Biomédicas, University of La Laguna, 38071 Tenerife, Spain
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Giraldez T, Rojas P, Jou J, Flores C, Alvarez de la Rosa D. The epithelial sodium channel δ-subunit: new notes for an old song. Am J Physiol Renal Physiol 2012; 303:F328-38. [PMID: 22573384 DOI: 10.1152/ajprenal.00116.2012] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Amiloride-sensitive epithelial Na(+) channels (ENaCs) can be formed by different combinations of four homologous subunits, named α, β, γ, and δ. In addition to providing an apical entry pathway for transepithelial Na(+) reabsorption in tight epithelia such as the kidney distal tubule and collecting duct, ENaCs are also expressed in nonepithelial cells, where they may play different functional roles. The δ-subunit of ENaC was originally identified in humans and is able to form amiloride-sensitive Na(+) channels alone or in combination with β and γ, generally resembling the canonical kidney ENaC formed by α, β, and γ. However, δ differs from α in its tissue distribution and channel properties. Despite the low sequence conservation between α and δ (37% identity), their similar functional characteristics provide an excellent model for exploring structural correlates of specific ENaC biophysical and pharmacological properties. Moreover, the study of cellular mechanisms modulating the activity of different ENaC subunit combinations provides an opportunity to gain insight into the regulation of the channel. In this review, we examine the evolution of ENaC genes, channel subunit composition, the distinct functional and pharmacological features that δ confers to ENaC, and how this can be exploited to better understand this ion channel. Finally, we briefly consider possible functional roles of the ENaC δ-subunit.
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Affiliation(s)
- Teresa Giraldez
- Research Division, University Hospital N.S. Candelaria, Santa Cruz de Tenerife, Tenerife, Spain
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Rosa DA, Wesch DL, Miranda P, Giraldez T. Epithelial sodium channel (ENaC) plasma membrane turnover is modified in channels containing δ subunits. FASEB J 2012. [DOI: 10.1096/fasebj.26.1_supplement.1068.8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | - Diana Luise Wesch
- Department of PhysiologyUniversity of La LagunaLa LagunaSpain
- Research UnitHospital N.S. CandelariaSanta Cruz de TenerifeSpain
| | - Pablo Miranda
- Department of PhysiologyUniversity of La LagunaLa LagunaSpain
- Research UnitHospital N.S. CandelariaSanta Cruz de TenerifeSpain
| | - Teresa Giraldez
- Research UnitHospital N.S. CandelariaSanta Cruz de TenerifeSpain
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Miranda P, Contreras JE, Wesch D, Sigworth FJ, Holmgren M, Giraldez T. State-Dependent FRET Reports Large Gating-Ring Motions in BK Channels. Biophys J 2012. [DOI: 10.1016/j.bpj.2011.11.3735] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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40
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Wesch D, Althaus M, Miranda P, Cruz-Muros I, Fronius M, González-Hernández T, Clauss WG, Alvarez de la Rosa D, Giraldez T. Differential N termini in epithelial Na+ channel δ-subunit isoforms modulate channel trafficking to the membrane. Am J Physiol Cell Physiol 2011; 302:C868-79. [PMID: 22159085 DOI: 10.1152/ajpcell.00255.2011] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The epithelial Na(+) channel (ENaC) is a heteromultimeric ion channel that plays a key role in Na(+) reabsorption across tight epithelia. The canonical ENaC is formed by three analogous subunits, α, β, and γ. A fourth ENaC subunit, named δ, is expressed in the nervous system of primates, where its role is unknown. The human δ-ENaC gene generates at least two splice isoforms, δ(1) and δ(2) , differing in the N-terminal sequence. Neurons in diverse areas of the human and monkey brain differentially express either δ(1) or δ(2) , with few cells coexpressing both isoforms, which suggests that they may play specific physiological roles. Here we show that heterologous expression of δ(1) in Xenopus oocytes and HEK293 cells produces higher current levels than δ(2) . Patch-clamp experiments showed no differences in single channel current magnitude and open probability between isoforms. Steady-state plasma membrane abundance accounts for the dissimilarity in macroscopic current levels. Differential trafficking between isoforms is independent of β- and γ-subunits, PY-motif-mediated endocytosis, or the presence of additional lysine residues in δ(2)-N terminus. Analysis of δ(2)-N terminus identified two sequences that independently reduce channel abundance in the plasma membrane. The δ(1) higher abundance is consistent with an increased insertion rate into the membrane, since endocytosis rates of both isoforms are indistinguishable. Finally, we conclude that δ-ENaC undergoes dynamin-independent endocytosis as opposed to αβγ-channels.
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Affiliation(s)
- Diana Wesch
- Research Division, University Hospital N.S. Candelaria, Spain
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41
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Rosa DA, Wesch D, Althaus M, Miranda P, Fronius M, Clauss WG, Giraldez T. Differential plasma membrane abundance of epithelial sodium channel δ subunit splice isoforms. FASEB J 2011. [DOI: 10.1096/fasebj.25.1_supplement.1041.45] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | - Diana Wesch
- Research UnitHospital Universitario Ntra. Sra. de CandelariaSanta Cruz de TenerifeSpain
- Department of PhysiologyUniversity of La LagunaLa LagunaSpain
| | - Mike Althaus
- Institute of Animal PhysiologyJustus‐Liebig UniversityGiessenGermany
| | - Pablo Miranda
- Research UnitHospital Universitario Ntra. Sra. de CandelariaSanta Cruz de TenerifeSpain
- Department of PhysiologyUniversity of La LagunaLa LagunaSpain
| | - Martin Fronius
- Institute of Animal PhysiologyJustus‐Liebig UniversityGiessenGermany
| | - Wolfgang G Clauss
- Institute of Animal PhysiologyJustus‐Liebig UniversityGiessenGermany
| | - Teresa Giraldez
- Research UnitHospital Universitario Ntra. Sra. de CandelariaSanta Cruz de TenerifeSpain
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Miranda P, Contreras J, Wesch DL, Sigworth FJ, Holmgren M, Giraldez T. Calcium Induces Structural Rearrangements of the Gating Ring of the Human BK Channel. Biophys J 2011. [DOI: 10.1016/j.bpj.2010.12.1636] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
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Hernández-Díaz I, Giraldez T, Arnau MR, Smits VAJ, Jaisser F, Farman N, Alvarez de la Rosa D. The mineralocorticoid receptor is a constitutive nuclear factor in cardiomyocytes due to hyperactive nuclear localization signals. Endocrinology 2010; 151:3888-99. [PMID: 20484457 DOI: 10.1210/en.2010-0099] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The mineralocorticoid receptor (MR), a member of the nuclear receptor family, mediates the action of aldosterone in target epithelia, enhancing sodium reabsorption. In addition, MR may have other physiological functions in nonepithelial tissues. Altered expression or inappropriate activation of cardiac MR is directly linked to the development of cardiac fibrosis, and MR blockade is beneficial for the treatment of heart failure. However, the physiological role, activation status, and target genes of MR in the heart are poorly known. Because ligand-free steroid receptors are typically cytoplasmic and translocate to the nucleus upon ligand binding, we examined the subcellular localization of MR under different corticosteroid levels using subcellular fractionation and immunostaining. Our results demonstrate that MR is a chromatin-bound factor in mouse left ventricle and in a cultured model of cardiomyocytes, HL-1 cells, regardless of circulating corticosteroid levels. Immunohistochemical localization of MR in human heart confirms the subcellular localization pattern. Mutation of nuclear localization signals (NLSs) demonstrates that MR constitutive nuclear localization mainly depends on the synergistic contribution of NLS0 and NLS1. Constitutive nuclear localization in HL-1 cells can be reverted by cotransfection of heat shock protein 90. Heat shock protein 90 expression levels in the mouse heart and HL-1 cells are lower than those found in other tissues, suggesting that low levels of cochaperones render MR NLSs hyperactive in cardiomyocytes. Even though MR is constitutively nuclear, corticosteroids still control the transactivation properties of the receptor in a model promoter, although other MR ligand-independent activities cannot be excluded.
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Affiliation(s)
- Iván Hernández-Díaz
- Departamento de Fisiología, Facultad de Medicina, Universidad de La Laguna, La Laguna 38071, Spain
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Wesch D, Miranda P, Afonso-Oramas D, Althaus M, Castro-Hernández J, Dominguez J, Morty RE, Clauss W, González-Hernández T, Alvarez de la Rosa D, Giraldez T. The neuronal-specific SGK1.1 kinase regulates {delta}-epithelial Na+ channel independently of PY motifs and couples it to phospholipase C signaling. Am J Physiol Cell Physiol 2010; 299:C779-90. [PMID: 20631247 DOI: 10.1152/ajpcell.00184.2010] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The δ-subunit of the epithelial Na(+) channel (ENaC) is expressed in neurons of the human and monkey central nervous system and forms voltage-independent, amiloride-sensitive Na(+) channels when expressed in heterologous systems. It has been proposed that δ-ENaC could affect neuronal excitability and participate in the transduction of ischemic signals during hypoxia or inflammation. The regulation of δ-ENaC activity is poorly understood. ENaC channels in kidney epithelial cells are regulated by the serum- and glucocorticoid-induced kinase 1 (SGK1). Recently, a new isoform of this kinase (SGK1.1) has been described in the central nervous system. Here we show that δ-ENaC isoforms and SGK1.1 are coexpressed in pyramidal neurons of the human and monkey (Macaca fascicularis) cerebral cortex. Coexpression of δβγ-ENaC and SGK1.1 in Xenopus oocytes increases amiloride-sensitive current and channel plasma membrane abundance. The kinase also exerts its effect when δ-subunits are expressed alone, indicating that the process is not dependent on accessory subunits or the presence of PY motifs in the channel. Furthermore, SGK1.1 action depends on its enzymatic activity and binding to phosphatidylinositol(4,5)-bisphosphate. Physiological or pharmacological activation of phospholipase C abrogates SGK1.1 interaction with the plasma membrane and modulation of δ-ENaC. Our data support a physiological role for SGK1.1 in the regulation of δ-ENaC through a pathway that differs from the classical one and suggest that the kinase could serve as an integrator of different signaling pathways converging on the channel.
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Affiliation(s)
- Diana Wesch
- Unidad de Investigacion, Hospital Universitario Ntra Sra Candelaria, Ctra Rosario 145, Santa Cruz de Tenerife, Spain
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Rosa DA, Hernandez‐Diaz I, Giraldez T. Molecular mechanisms involved in the constitutive nuclear localization of the mineralocorticoid receptor in cardiac myocytes. FASEB J 2010. [DOI: 10.1096/fasebj.24.1_supplement.1040.11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Diego Alvarez Rosa
- Department of PhysiologyUniversity of La LagunaLa LagunaSpain
- Instituto de Tecnologias BiomedicasLa LagunaSpain
| | - Ivan Hernandez‐Diaz
- Department of PhysiologyUniversity of La LagunaLa LagunaSpain
- Instituto de Tecnologias BiomedicasLa LagunaSpain
| | - Teresa Giraldez
- Research UnitHospital Universitario Ntra. Sra. de CandelariaSanta Cruz de TenerifeSpain
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Wesch D, Miranda P, de la Rosa DA, Giraldez T. Regulation of Delta-Enac Ion Channels by the Neuronal-Specific Sgk1.1 Kinase. Biophys J 2010. [DOI: 10.1016/j.bpj.2009.12.541] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
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47
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Wesch D, de la Rosa DA, Giraldez T. Quantitative Analysis Of DEG/ENaC Subunits Interaction. Biophys J 2009. [DOI: 10.1016/j.bpj.2008.12.2767] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
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48
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Rosa DA, Hernandez‐Diaz I, Giraldez T. Probing mineralocorticoid and glucocorticoid receptor physical interaction with specific gene promoters in the mouse heart. FASEB J 2008. [DOI: 10.1096/fasebj.22.1_supplement.742.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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49
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Giraldez T, Afonso-Oramas D, Cruz-Muros I, Garcia-Marin V, Pagel P, González-Hernández T, Alvarez de la Rosa D. Cloning and functional expression of a new epithelial sodium channel delta subunit isoform differentially expressed in neurons of the human and monkey telencephalon. J Neurochem 2007; 102:1304-15. [PMID: 17472699 DOI: 10.1111/j.1471-4159.2007.04622.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Epithelial sodium channel (ENaC) is a member of the ENaC/degenerin family of amiloride-sensitive, non-voltage gated sodium ion channels. ENaC alpha, beta and gamma subunits are abundantly expressed in epithelial tissues, where they have been well characterized. An ENaC delta subunit has also been described in the human nervous system, although its histological distribution pattern remains unexplored. We have now isolated a novel ENaC delta isoform (delta2) from human brain and studied the expression pattern of both the known (delta1) and the new (delta2) isoforms in the human and monkey telencephalon. ENaC delta2 is produced by a combination of alternative transcription start sites, a frame shift in exon 3 and alternative splicing of exon 4. It forms functional amiloride-sensitive sodium channels when co-expressed with ENaC beta and gamma accessory subunits. Comparison with the classical ENaC channel (alphabetagamma) indicates that the interaction between delta2, beta and gamma is functionally inefficient. Both ENaC delta isoforms are widely expressed in pyramidal cells of the human and monkey cerebral cortex and in different neuronal populations of telencephalic subcortical nuclei, but double-labelling experiments demonstrated a low level of co-localization between isoforms (5-8%), suggesting specific functional roles for each of them.
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Affiliation(s)
- Teresa Giraldez
- Unidad de Farmacología, Universidad de La Laguna, La Laguna, Tenerife, Spain.
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50
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Pec MK, Artwohl M, Fernández JJ, Souto ML, Alvarez de la Rosa D, Giraldez T, Valenzuela-Fernández A, Díaz-González F. Chemical modulation of VLA integrin affinity in human breast cancer cells. Exp Cell Res 2007; 313:1121-34. [PMID: 17331499 DOI: 10.1016/j.yexcr.2007.01.015] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2006] [Revised: 01/02/2007] [Accepted: 01/21/2007] [Indexed: 12/31/2022]
Abstract
The fact that disruption of integrin-extracellular matrix contacts leads to cell death, has converted cell adhesion into a potential target for the control of invasive cancer. In this work, we studied the functional consequences of the interference with the activity of the very late activation antigen (VLA) family of integrins in human breast cancer cell lines of distinct malignancy. The alpha2beta1-mediated adhesion reduced the entry of highly malignant, hormone-independent breast cancer cells into apoptosis. Adhesion of breast cancer cells through the VLA integrins alpha2beta1 and alpha5beta1 was significantly reduced by an apoptosis-inducing natural triterpenoid, dehydrothyrsiferol (DT), when studied on low amounts of extracellular matrix. This effect was dose-dependent, not related to cell toxicity and not shared with apoptosis-inducing standard chemotherapeutics, such as doxorubicin and taxol. The compound did not affect either the cell surface expression level of VLA integrins or cell distribution of vinculin and actin during cell spreading. In addition, neither phosphorylation of the focal adhesion kinase pp125FAK on Tyr397 nor the protein kinase B (Akt/PKB) on Ser473 was significantly altered by DT. The integrin activation level, assessed by binding of soluble collagen to the alpha2beta1 integrin, was reduced upon cell treatment with DT. Importantly, the TS2/16, an anti-beta1 activating monoclonal antibody was able to rescue DT-treated cells from apoptosis. Since the activation state of integrins is increasingly recognized as an essential factor in metastasis formation, findings presented herein reveal that the chemical regulation of integrin affinity may be a potential therapeutic strategy in cancer therapy.
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Affiliation(s)
- Martina K Pec
- Servicio de Reumatología, Hospital Universitario de Canarias, C/Ofra s/n, La Cuesta, 38320 La Laguna, Santa Cruz de Tenerife, Spain
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