1
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Baltasar-Marchueta M, Llona L, M-Alicante S, Barbolla I, Ibarluzea MG, Ramis R, Salomon AM, Fundora B, Araujo A, Muguruza-Montero A, Nuñez E, Pérez-Olea S, Villanueva C, Leonardo A, Arrasate S, Sotomayor N, Villarroel A, Bergara A, Lete E, González-Díaz H. Identification of Riluzole derivatives as novel calmodulin inhibitors with neuroprotective activity by a joint synthesis, biosensor, and computational guided strategy. Biomed Pharmacother 2024; 174:116602. [PMID: 38636396 DOI: 10.1016/j.biopha.2024.116602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2024] [Revised: 04/10/2024] [Accepted: 04/11/2024] [Indexed: 04/20/2024] Open
Abstract
The development of new molecules for the treatment of calmodulin related cardiovascular or neurodegenerative diseases is an interesting goal. In this work, we introduce a novel strategy with four main steps: (1) chemical synthesis of target molecules, (2) Förster Resonance Energy Transfer (FRET) biosensor development and in vitro biological assay of new derivatives, (3) Cheminformatics models development and in vivo activity prediction, and (4) Docking studies. This strategy is illustrated with a case study. Firstly, a series of 4-substituted Riluzole derivatives 1-3 were synthetized through a strategy that involves the construction of the 4-bromoriluzole framework and its further functionalization via palladium catalysis or organolithium chemistry. Next, a FRET biosensor for monitoring Ca2+-dependent CaM-ligands interactions has been developed and used for the in vitro assay of Riluzole derivatives. In particular, the best inhibition (80%) was observed for 4-methoxyphenylriluzole 2b. Besides, we trained and validated a new Networks Invariant, Information Fusion, Perturbation Theory, and Machine Learning (NIFPTML) model for predicting probability profiles of in vivo biological activity parameters in different regions of the brain. Next, we used this model to predict the in vivo activity of the compounds experimentally studied in vitro. Last, docking study conducted on Riluzole and its derivatives has provided valuable insights into their binding conformations with the target protein, involving calmodulin and the SK4 channel. This new combined strategy may be useful to reduce assay costs (animals, materials, time, and human resources) in the drug discovery process of calmodulin inhibitors.
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Affiliation(s)
- Maider Baltasar-Marchueta
- Department of Organic and Inorganic Chemistry, University of the Basque Country UPV/EHU, Leioa 48940, Spain
| | - Leire Llona
- Department of Organic and Inorganic Chemistry, University of the Basque Country UPV/EHU, Leioa 48940, Spain
| | | | - Iratxe Barbolla
- Department of Organic and Inorganic Chemistry, University of the Basque Country UPV/EHU, Leioa 48940, Spain
| | - Markel Garcia Ibarluzea
- Donostia International Physics Center, Donostia, Spain; Departament of Physics, University of the Basque Country, UPV/EHU, Leioa, Spain
| | - Rafael Ramis
- Donostia International Physics Center, Donostia, Spain; Departament of Physics, University of the Basque Country, UPV/EHU, Leioa, Spain
| | - Ane Miren Salomon
- Department of Organic and Inorganic Chemistry, University of the Basque Country UPV/EHU, Leioa 48940, Spain
| | - Brenda Fundora
- Department of Organic and Inorganic Chemistry, University of the Basque Country UPV/EHU, Leioa 48940, Spain
| | - Ariane Araujo
- Biofisika Institute, CSIC-UPV/EHU, Leioa 48940, Spain
| | | | - Eider Nuñez
- Biofisika Institute, CSIC-UPV/EHU, Leioa 48940, Spain
| | - Scarlett Pérez-Olea
- Department of Organic and Inorganic Chemistry, University of the Basque Country UPV/EHU, Leioa 48940, Spain
| | - Christian Villanueva
- Department of Organic and Inorganic Chemistry, University of the Basque Country UPV/EHU, Leioa 48940, Spain
| | - Aritz Leonardo
- Donostia International Physics Center, Donostia, Spain; Departament of Physics, University of the Basque Country, UPV/EHU, Leioa, Spain
| | - Sonia Arrasate
- Department of Organic and Inorganic Chemistry, University of the Basque Country UPV/EHU, Leioa 48940, Spain
| | - Nuria Sotomayor
- Department of Organic and Inorganic Chemistry, University of the Basque Country UPV/EHU, Leioa 48940, Spain
| | | | - Aitor Bergara
- Donostia International Physics Center, Donostia, Spain; Departament of Physics, University of the Basque Country, UPV/EHU, Leioa, Spain.
| | - Esther Lete
- Department of Organic and Inorganic Chemistry, University of the Basque Country UPV/EHU, Leioa 48940, Spain.
| | - Humberto González-Díaz
- Department of Organic and Inorganic Chemistry, University of the Basque Country UPV/EHU, Leioa 48940, Spain; Biofisika Institute, CSIC-UPV/EHU, Leioa 48940, Spain; IKERBASQUE, Basque Foundation for Science, Bilbao 48011, Spain.
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2
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Nuñez E, Muguruza-Montero A, Alicante SM, Villarroel A. Fluorometric Measurement of Calmodulin-Dependent Peptide-Protein Interactions Using Dansylated Calmodulin. Bio Protoc 2024; 14:e4963. [PMID: 38618173 PMCID: PMC11006803 DOI: 10.21769/bioprotoc.4963] [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] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Revised: 02/07/2024] [Accepted: 02/07/2024] [Indexed: 04/16/2024] Open
Abstract
The assessment of peptide-protein interactions is a pivotal aspect of studying the functionality and mechanisms of various bioactive peptides. In this context, it is essential to employ methods that meet specific criteria, including sensitivity, biocompatibility, versatility, simplicity, and the ability to offer real-time monitoring. In cellular contexts, only a few proteins naturally possess inherent fluorescence, specifically those containing aromatic amino acids, particularly tryptophan. Nonetheless, by covalently attaching fluorescent markers, almost all proteins can be modified for monitoring purposes. Among the early extrinsic fluorescent probes designed for this task, dansyl chloride (DNSC) is a notable option due to its versatile nature and reliable performance. DNSC has been the primary choice as a fluorogenic derivatizing reagent for analyzing amino acids in proteins and peptides for an extended period of time. In our work, we have effectively utilized the distinctive properties of dansylated-calmodulin (D-CaM) for monitoring the interaction dynamics between proteins and peptides, particularly in the context of their association with calmodulin (CaM), a calcium-dependent regulatory protein. This technique not only enables us to scrutinize the affinity of diverse ligands but also sheds light on the intricate role played by calcium in these interactions. Key features • Dynamic fluorescence and real-time monitoring: dansyl-modified CaM enables sensitive, real-time fluorescence, providing valuable insights into the dynamics of molecular interactions and ligand binding. • Selective interaction and stable fluorescent adducts: DNSC selectively interacts with primary amino groups, ensuring specific detection and forming stable fluorescent sulfonamide adducts. • Versatility in research and ease of identification: D-CaM is a versatile tool in biological research, facilitating identification, precise quantification, and drug assessment for therapeutic development. • Sensitivity to surrounding alterations: D-CaM exhibits sensitivity to its surroundings, particularly ligand-induced changes, offering subtle insights into molecular interactions and environmental influences.
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Affiliation(s)
- Eider Nuñez
- Instituto Biofisika, CSIC-UPV/EHU, Leioa, Spain
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3
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Saez-Matia A, Ibarluzea MG, M-Alicante S, Muguruza-Montero A, Nuñez E, Ramis R, Ballesteros OR, Lasa-Goicuria D, Fons C, Gallego M, Casis O, Leonardo A, Bergara A, Villarroel A. MLe-KCNQ2: An Artificial Intelligence Model for the Prognosis of Missense KCNQ2 Gene Variants. Int J Mol Sci 2024; 25:2910. [PMID: 38474157 DOI: 10.3390/ijms25052910] [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] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2024] [Revised: 02/27/2024] [Accepted: 02/29/2024] [Indexed: 03/14/2024] Open
Abstract
Despite the increasing availability of genomic data and enhanced data analysis procedures, predicting the severity of associated diseases remains elusive in the absence of clinical descriptors. To address this challenge, we have focused on the KV7.2 voltage-gated potassium channel gene (KCNQ2), known for its link to developmental delays and various epilepsies, including self-limited benign familial neonatal epilepsy and epileptic encephalopathy. Genome-wide tools often exhibit a tendency to overestimate deleterious mutations, frequently overlooking tolerated variants, and lack the capacity to discriminate variant severity. This study introduces a novel approach by evaluating multiple machine learning (ML) protocols and descriptors. The combination of genomic information with a novel Variant Frequency Index (VFI) builds a robust foundation for constructing reliable gene-specific ML models. The ensemble model, MLe-KCNQ2, formed through logistic regression, support vector machine, random forest and gradient boosting algorithms, achieves specificity and sensitivity values surpassing 0.95 (AUC-ROC > 0.98). The ensemble MLe-KCNQ2 model also categorizes pathogenic mutations as benign or severe, with an area under the receiver operating characteristic curve (AUC-ROC) above 0.67. This study not only presents a transferable methodology for accurately classifying KCNQ2 missense variants, but also provides valuable insights for clinical counseling and aids in the determination of variant severity. The research context emphasizes the necessity of precise variant classification, especially for genes like KCNQ2, contributing to the broader understanding of gene-specific challenges in the field of genomic research. The MLe-KCNQ2 model stands as a promising tool for enhancing clinical decision making and prognosis in the realm of KCNQ2-related pathologies.
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Affiliation(s)
| | - Markel G Ibarluzea
- Physics Department, Universidad del País Vasco, UPV/EHU, 48940 Leioa, Spain
- Donostia International Physics Center, 20018 Donostia, Spain
| | - Sara M-Alicante
- Instituto Biofisika, CSIC-UPV/EHU, 48940 Leioa, Spain
- Physics Department, Universidad del País Vasco, UPV/EHU, 48940 Leioa, Spain
| | | | - Eider Nuñez
- Instituto Biofisika, CSIC-UPV/EHU, 48940 Leioa, Spain
- Physics Department, Universidad del País Vasco, UPV/EHU, 48940 Leioa, Spain
| | - Rafael Ramis
- Physics Department, Universidad del País Vasco, UPV/EHU, 48940 Leioa, Spain
- Donostia International Physics Center, 20018 Donostia, Spain
| | - Oscar R Ballesteros
- Physics Department, Universidad del País Vasco, UPV/EHU, 48940 Leioa, Spain
- Centro de Física de Materiales CFM, CSIC-UPV/EHU, 20018 Donostia, Spain
| | | | - Carmen Fons
- Pediatric Neurology Department, Sant Joan de Déu Hospital, Institut de Recerca Sant Joan de Déu, Barcelona University, 08950 Barcelona, Spain
| | - Mónica Gallego
- Departamento de Fisiología, Universidad del País Vasco, UPV/EHU, 01006 Vitoria-Gasteiz, Spain
| | - Oscar Casis
- Departamento de Fisiología, Universidad del País Vasco, UPV/EHU, 01006 Vitoria-Gasteiz, Spain
| | - Aritz Leonardo
- Physics Department, Universidad del País Vasco, UPV/EHU, 48940 Leioa, Spain
- Donostia International Physics Center, 20018 Donostia, Spain
| | - Aitor Bergara
- Physics Department, Universidad del País Vasco, UPV/EHU, 48940 Leioa, Spain
- Donostia International Physics Center, 20018 Donostia, Spain
- Centro de Física de Materiales CFM, CSIC-UPV/EHU, 20018 Donostia, Spain
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4
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Nuñez E, Jones F, Muguruza-Montero A, Urrutia J, Aguado A, Malo C, Bernardo-Seisdedos G, Domene C, Millet O, Gamper N, Villarroel A. Redox regulation of K V7 channels through EF3 hand of calmodulin. eLife 2023; 12:e81961. [PMID: 36803414 PMCID: PMC9988260 DOI: 10.7554/elife.81961] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Accepted: 02/10/2023] [Indexed: 02/22/2023] Open
Abstract
Neuronal KV7 channels, important regulators of cell excitability, are among the most sensitive proteins to reactive oxygen species. The S2S3 linker of the voltage sensor was reported as a site-mediating redox modulation of the channels. Recent structural insights reveal potential interactions between this linker and the Ca2+-binding loop of the third EF-hand of calmodulin (CaM), which embraces an antiparallel fork formed by the C-terminal helices A and B, constituting the calcium responsive domain (CRD). We found that precluding Ca2+ binding to the EF3 hand, but not to EF1, EF2, or EF4 hands, abolishes oxidation-induced enhancement of KV7.4 currents. Monitoring FRET (Fluorescence Resonance Energy Transfer) between helices A and B using purified CRDs tagged with fluorescent proteins, we observed that S2S3 peptides cause a reversal of the signal in the presence of Ca2+ but have no effect in the absence of this cation or if the peptide is oxidized. The capacity of loading EF3 with Ca2+ is essential for this reversal of the FRET signal, whereas the consequences of obliterating Ca2+ binding to EF1, EF2, or EF4 are negligible. Furthermore, we show that EF3 is critical for translating Ca2+ signals to reorient the AB fork. Our data are consistent with the proposal that oxidation of cysteine residues in the S2S3 loop relieves KV7 channels from a constitutive inhibition imposed by interactions between the EF3 hand of CaM which is crucial for this signaling.
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Affiliation(s)
| | - Frederick Jones
- School of Biomedical Sciences, Faculty of Biological Sciences, University of LeedsLeedsUnited Kingdom
| | | | | | | | | | | | - Carmen Domene
- Department of Chemistry, University of BathBathUnited Kingdom
- Department of Chemistry, University of OxfordOxfordUnited Kingdom
| | - Oscar Millet
- Protein Stability and Inherited Disease Laboratory, CIC bioGUNEDerioSpain
| | - Nikita Gamper
- School of Biomedical Sciences, Faculty of Biological Sciences, University of LeedsLeedsUnited Kingdom
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Revuelta M, Urrutia J, Villarroel A, Casis O. Microglia-Mediated Inflammation and Neural Stem Cell Differentiation in Alzheimer's Disease: Possible Therapeutic Role of K V1.3 Channel Blockade. Front Cell Neurosci 2022; 16:868842. [PMID: 35530176 PMCID: PMC9070300 DOI: 10.3389/fncel.2022.868842] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [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: 02/03/2022] [Accepted: 03/31/2022] [Indexed: 12/14/2022] Open
Abstract
Increase of deposits of amyloid β peptides in the extracellular matrix is landmark during Alzheimer’s Disease (AD) due to the imbalance in the production vs. clearance. This accumulation of amyloid β deposits triggers microglial activation. Microglia plays a dual role in AD, a protective role by clearing the deposits of amyloid β peptides increasing the phagocytic response (CD163, IGF-1 or BDNF) and a cytotoxic role, releasing free radicals (ROS or NO) and proinflammatory cytokines (TNF-α, IL-1β) in response to reactive gliosis activated by the amyloid β aggregates. Microglia activation correlated with an increase KV1.3 channels expression, protein levels and current density. Several studies highlight the importance of KV1.3 in the activation of inflammatory response and inhibition of neural progenitor cell proliferation and neuronal differentiation. However, little is known about the pathways of this activation in neural stem cells differentiation and proliferation and the role in amyloid β accumulation. In recent studies using in vitro cells derived from mice models, it has been demonstrated that KV1.3 blockers inhibit microglia-mediated neurotoxicity in culture reducing the expression and production of the pro-inflammatory cytokines IL-1β and TNF-α through the NF-kB and p38MAPK pathway. Overall, we conclude that KV1.3 blockers change the course of AD development, reducing microglial cytotoxic activation and increasing neural stem cell differentiation. However, further investigations are needed to establish the specific pathway and to validate the use of this blocker as therapeutic treatment in Alzheimer patients.
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Affiliation(s)
- Miren Revuelta
- Department of Physiology, Faculty of Medicine and Nursery, University of the Basque Country (UPV/EHU), Leioa, Spain
| | - Janire Urrutia
- Department of Physiology, Faculty of Medicine and Nursery, University of the Basque Country (UPV/EHU), Leioa, Spain
| | - Alvaro Villarroel
- Instituto Biofisika, Consejo Superior de Investigaciones Científicas (CSIC)-University of the Basque Country/Euskal Herriko Unibertsitatea (UPV/EHU), Leioa, Spain
| | - Oscar Casis
- Department of Physiology, Faculty of Pharmacy, University of the Basque Country (UPV/EHU), Vitoria-Gasteiz, Spain
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6
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Muguruza-Montero A, Ramis R, Nuñez E, R Ballesteros O, G Ibarluzea M, Araujo A, M-Alicante S, Urrutia J, Leonardo A, Bergara A, Villarroel A. Do calmodulin binding IQ motifs have built-in capping domains? Protein Sci 2021; 30:2029-2041. [PMID: 34392571 PMCID: PMC8442972 DOI: 10.1002/pro.4170] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [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: 06/21/2021] [Revised: 07/31/2021] [Accepted: 08/04/2021] [Indexed: 01/28/2023]
Abstract
Most calmodulin (CaM) targets are α-helices. It is not clear if CaM induces the adoption of an α-helix configuration to its targets or if those targets are selected as they spontaneously adopt an α-helical conformation. Other than an α-helix propensity, there is a great variety of CaM targets with little more in common. One exception to this rule is the IQ site that can be recognized in a number of targets, such as those ion channels belonging to the KCNQ family. Although there is negligible sequence similarity between the IQ motif and the docking site on SK2 channels, both adopt a similar three-dimensional disposition. The isolated SK2 target presents a pre-folded core region that becomes fully α-helical upon binding to CaM. The existence of this pre-folded state suggests the occurrence of capping within CaM targets. In this review, we examine the capping properties within the residues flanking this core domain, and relate known IQ motifs and capping.
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Affiliation(s)
| | - Rafael Ramis
- Donostia International Physics Center, Donostia, Spain.,Departamento de Física, Universidad del País Vasco, UPV/EHU, Leioa, Spain
| | - Eider Nuñez
- LaboKCNQ, Barrio Sarriena, Leioa, Spain.,Instituto Biofisika, CSIC-UPV/EHU, Leioa, Spain
| | - Oscar R Ballesteros
- Centro de Física de Materiales CFM, CSIC-UPV/EHU, Donostia, Spain.,Departamento de Física, Universidad del País Vasco, UPV/EHU, Leioa, Spain
| | - Markel G Ibarluzea
- Donostia International Physics Center, Donostia, Spain.,Departamento de Física, Universidad del País Vasco, UPV/EHU, Leioa, Spain
| | - Ariane Araujo
- LaboKCNQ, Barrio Sarriena, Leioa, Spain.,Instituto Biofisika, CSIC-UPV/EHU, Leioa, Spain
| | | | - Janire Urrutia
- LaboKCNQ, Barrio Sarriena, Leioa, Spain.,Department of Physiology, Faculty of Medicine and Nursery, UPV/EHU, Leioa, Spain
| | - Aritz Leonardo
- Donostia International Physics Center, Donostia, Spain.,Departamento de Física, Universidad del País Vasco, UPV/EHU, Leioa, Spain
| | - Aitor Bergara
- Donostia International Physics Center, Donostia, Spain.,Centro de Física de Materiales CFM, CSIC-UPV/EHU, Donostia, Spain.,Departamento de Física, Universidad del País Vasco, UPV/EHU, Leioa, Spain
| | - Alvaro Villarroel
- LaboKCNQ, Barrio Sarriena, Leioa, Spain.,Instituto Biofisika, CSIC-UPV/EHU, Leioa, Spain
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7
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Urrutia J, Aguado A, Gomis-Perez C, Muguruza-Montero A, Ballesteros OR, Zhang J, Nuñez E, Malo C, Chung HJ, Leonardo A, Bergara A, Villarroel A. An epilepsy-causing mutation leads to co-translational misfolding of the Kv7.2 channel. BMC Biol 2021; 19:109. [PMID: 34020651 PMCID: PMC8138981 DOI: 10.1186/s12915-021-01040-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [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: 08/21/2020] [Accepted: 04/29/2021] [Indexed: 12/21/2022] Open
Abstract
Background The amino acid sequence of proteins generally carries all the necessary information for acquisition of native conformations, but the vectorial nature of translation can additionally determine the folding outcome. Such consideration is particularly relevant in human diseases associated to inherited mutations leading to structural instability, aggregation, and degradation. Mutations in the KCNQ2 gene associated with human epilepsy have been suggested to cause misfolding of the encoded Kv7.2 channel. Although the effect on folding of mutations in some domains has been studied, little is known of the way pathogenic variants located in the calcium responsive domain (CRD) affect folding. Here, we explore how a Kv7.2 mutation (W344R) located in helix A of the CRD and associated with hereditary epilepsy interferes with channel function. Results We report that the epilepsy W344R mutation within the IQ motif of CRD decreases channel function, but contrary to other mutations at this site, it does not impair the interaction with Calmodulin (CaM) in vitro, as monitored by multiple in vitro binding assays. We find negligible impact of the mutation on the structure of the complex by molecular dynamic computations. In silico studies revealed two orientations of the side chain, which are differentially populated by WT and W344R variants. Binding to CaM is impaired when the mutated protein is produced in cellulo but not in vitro, suggesting that this mutation impedes proper folding during translation within the cell by forcing the nascent chain to follow a folding route that leads to a non-native configuration, and thereby generating non-functional ion channels that fail to traffic to proper neuronal compartments. Conclusions Our data suggest that the key pathogenic mechanism of Kv7.2 W344R mutation involves the failure to adopt a configuration that can be recognized by CaM in vivo but not in vitro. Supplementary Information The online version contains supplementary material available at 10.1186/s12915-021-01040-1.
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Affiliation(s)
- Janire Urrutia
- Instituto Biofisika, CSIC-UPV/EHU, 48940, Leioa, Spain.,Present address: Department of Physiology, Faculty of Medicine and Nursery, UPV/EHU, 48940, Leioa, Spain
| | | | - Carolina Gomis-Perez
- Instituto Biofisika, CSIC-UPV/EHU, 48940, Leioa, Spain.,Present address: Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT, USA
| | | | | | - Jiaren Zhang
- Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Eider Nuñez
- Instituto Biofisika, CSIC-UPV/EHU, 48940, Leioa, Spain
| | | | - Hee Jung Chung
- Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Aritz Leonardo
- Departamento de Física Aplicada II, Universidad del País Vasco, UPV/EHU, 48940, Leioa, Spain.,Donostia International Physics Center, 20018, Donostia, Spain
| | - Aitor Bergara
- Centro de Física de Materiales CFM, CSIC-UPV/EHU, 20018, Donostia, Spain.,Donostia International Physics Center, 20018, Donostia, Spain.,Departmento de Materia Condensada, Universidad del País Vasco, UPV/EHU, 48940, Leioa, Spain
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8
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Alaimo A, Lorenzoni M, Ambrosino P, Bertossi A, Bisio A, Macchia A, Zoni E, Genovesi S, Cambuli F, Foletto V, De Felice D, Soldovieri MV, Mosca I, Gandolfi F, Brunelli M, Petris G, Cereseto A, Villarroel A, Thalmann G, Carbone FG, Kruithof-de Julio M, Barbareschi M, Romanel A, Taglialatela M, Lunardi A. Calcium cytotoxicity sensitizes prostate cancer cells to standard-of-care treatments for locally advanced tumors. Cell Death Dis 2020; 11:1039. [PMID: 33288740 PMCID: PMC7721710 DOI: 10.1038/s41419-020-03256-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [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: 08/12/2020] [Revised: 10/20/2020] [Accepted: 10/23/2020] [Indexed: 12/30/2022]
Abstract
Therapy resistance is a major roadblock in oncology. Exacerbation of molecular dysfunctions typical of cancer cells have proven effective in twisting oncogenic mechanisms to lethal conditions, thus offering new therapeutic avenues for cancer treatment. Here, we demonstrate that selective agonists of Transient Receptor Potential cation channel subfamily M member 8 (TRPM8), a cation channel characteristic of the prostate epithelium frequently overexpressed in advanced stage III/IV prostate cancers (PCa), sensitize therapy refractory models of PCa to radio, chemo or hormonal treatment. Overall, our study demonstrates that pharmacological-induced Ca2+ cytotoxicity is an actionable strategy to sensitize cancer cells to standard therapies.
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Affiliation(s)
- Alessandro Alaimo
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Trento, Italy
| | - Marco Lorenzoni
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Trento, Italy
| | - Paolo Ambrosino
- Department of Science and Technology (DST), University of Sannio, Benevento, Italy
| | - Arianna Bertossi
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Trento, Italy
| | - Alessandra Bisio
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Trento, Italy
| | - Alice Macchia
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Trento, Italy
| | - Eugenio Zoni
- Department for BioMedical Research, Urology Research Laboratory, University of Bern, Bern, Switzerland
| | - Sacha Genovesi
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Trento, Italy
| | - Francesco Cambuli
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Trento, Italy
| | - Veronica Foletto
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Trento, Italy
| | - Dario De Felice
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Trento, Italy
| | | | - Ilaria Mosca
- Department of Medicine and Health Sciences, University of Molise, Campobasso, Italy
| | - Francesco Gandolfi
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Trento, Italy
| | - Matteo Brunelli
- Department of Pathology AOUI, University of Verona, Verona, Italy
| | - Gianluca Petris
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Trento, Italy
| | - Anna Cereseto
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Trento, Italy
| | - Alvaro Villarroel
- Biofisika Institute (CSIC, UPV/EHU), University of the Basque Country, Leioa, Spain
| | - George Thalmann
- Department for BioMedical Research, Urology Research Laboratory, University of Bern, Bern, Switzerland.,Department of Urology, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | | | - Marianna Kruithof-de Julio
- Department for BioMedical Research, Urology Research Laboratory, University of Bern, Bern, Switzerland.,Department of Urology, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | | | - Alessandro Romanel
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Trento, Italy
| | | | - Andrea Lunardi
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Trento, Italy.
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Lazo PA, García JL, Gómez-Puertas P, Marcos-Alcalde Í, Arjona C, Villarroel A, González-Sarmiento R, Fons C. Novel Dominant KCNQ2 Exon 7 Partial In-Frame Duplication in a Complex Epileptic and Neurodevelopmental Delay Syndrome. Int J Mol Sci 2020; 21:ijms21124447. [PMID: 32585800 PMCID: PMC7352878 DOI: 10.3390/ijms21124447] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Revised: 06/17/2020] [Accepted: 06/18/2020] [Indexed: 12/23/2022] Open
Abstract
Complex neurodevelopmental syndromes frequently have an unknown etiology, in which genetic factors play a pathogenic role. This study utilizes whole-exome sequencing (WES) to examine four members of a family with a son presenting, since birth, with epileptic-like crises, combined with cerebral palsy, severe neuromotor and developmental delay, dystonic tetraparexia, axonal motor affectation, and hyper-excitability of unknown origin. The WES study detected within the patient a de novo heterozygous in-frame duplication of thirty-six nucleotides within exon 7 of the human KCNQ2 gene. This insertion duplicates the first twelve amino acids of the calmodulin binding site I. Molecular dynamics simulations of this KCNQ2 peptide duplication, modelled on the 3D structure of the KCNQ2 protein, suggest that the duplication may lead to the dysregulation of calcium inhibition of this protein function.
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Affiliation(s)
- Pedro A. Lazo
- Molecular Mechanisms of Cancer Program, Instituto de Biología Molecular y Celular del Cáncer, Consejo Superior de Investigaciones Científicas (CSIC), Universidad de Salamanca, 30007 Salamanca, Spain; (J.L.G.); (R.G.-S.)
- Instituto de Investigación Biomédica de Salamanca (IBSAL), Hospital Universitario de Salamanca, 30007 Salamanca, Spain
- Correspondence:
| | - Juan L. García
- Molecular Mechanisms of Cancer Program, Instituto de Biología Molecular y Celular del Cáncer, Consejo Superior de Investigaciones Científicas (CSIC), Universidad de Salamanca, 30007 Salamanca, Spain; (J.L.G.); (R.G.-S.)
- Instituto de Investigación Biomédica de Salamanca (IBSAL), Hospital Universitario de Salamanca, 30007 Salamanca, Spain
| | - Paulino Gómez-Puertas
- Centro de Biología Molecular Severo Ochoa, CSIC-Universidad Autónoma de Madrid, Cantoblanco, E-28049 Madrid, Spain; (P.G.-P.); (Í.M.-A.)
| | - Íñigo Marcos-Alcalde
- Centro de Biología Molecular Severo Ochoa, CSIC-Universidad Autónoma de Madrid, Cantoblanco, E-28049 Madrid, Spain; (P.G.-P.); (Í.M.-A.)
- Biosciences Research Institute, School of Experimental Sciences, Universidad Francisco de Vitoria, 28223 Madrid, Spain
| | - Cesar Arjona
- Institut de Recerca Sant Joan de Déu, Esplugues de Llobregat, 08950 Barcelona, Spain; (C.A.); (C.F.)
- Instituto Pediátrico de Enfermedades Raras (IPER), Hospital Sant Joan de Déu, 08950 Barcelona, Spain
| | - Alvaro Villarroel
- Instituto de Biofísica, Consejo Superior de Investigaciones Científicas (CSIC), Universidad del País Vasco, 48940 Bilbao, Spain;
| | - Rogelio González-Sarmiento
- Molecular Mechanisms of Cancer Program, Instituto de Biología Molecular y Celular del Cáncer, Consejo Superior de Investigaciones Científicas (CSIC), Universidad de Salamanca, 30007 Salamanca, Spain; (J.L.G.); (R.G.-S.)
- Instituto de Investigación Biomédica de Salamanca (IBSAL), Hospital Universitario de Salamanca, 30007 Salamanca, Spain
- Unidad de Genética Molecular, Departamento de Medicina, Universidad de Salamanca, 37008 Salamanca, Spain
| | - Carmen Fons
- Institut de Recerca Sant Joan de Déu, Esplugues de Llobregat, 08950 Barcelona, Spain; (C.A.); (C.F.)
- Neurology Department, Hospital Sant Joan de Déu, Sant Joan de Déu Research Institute and CIBERER, Instituto de Salud Carlos III, 08950 Barcelona, Spain
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10
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Núñez E, Muguruza-Montero A, Villarroel A. Atomistic Insights of Calmodulin Gating of Complete Ion Channels. Int J Mol Sci 2020; 21:ijms21041285. [PMID: 32075037 PMCID: PMC7072864 DOI: 10.3390/ijms21041285] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 02/07/2020] [Accepted: 02/12/2020] [Indexed: 12/13/2022] Open
Abstract
Intracellular calcium is essential for many physiological processes, from neuronal signaling and exocytosis to muscle contraction and bone formation. Ca2+ signaling from the extracellular medium depends both on membrane potential, especially controlled by ion channels selective to K+, and direct permeation of this cation through specialized channels. Calmodulin (CaM), through direct binding to these proteins, participates in setting the membrane potential and the overall permeability to Ca2+. Over the past years many structures of complete channels in complex with CaM at near atomic resolution have been resolved. In combination with mutagenesis-function, structural information of individual domains and functional studies, different mechanisms employed by CaM to control channel gating are starting to be understood at atomic detail. Here, new insights regarding four types of tetrameric channels with six transmembrane (6TM) architecture, Eag1, SK2/SK4, TRPV5/TRPV6 and KCNQ1–5, and its regulation by CaM are described structurally. Different CaM regions, N-lobe, C-lobe and EF3/EF4-linker play prominent signaling roles in different complexes, emerging the realization of crucial non-canonical interactions between CaM and its target that are only evidenced in the full-channel structure. Different mechanisms to control gating are used, including direct and indirect mechanical actuation over the pore, allosteric control, indirect effect through lipid binding, as well as direct plugging of the pore. Although each CaM lobe engages through apparently similar alpha-helices, they do so using different docking strategies. We discuss how this allows selective action of drugs with great therapeutic potential.
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11
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Alaimo A, Etxeberria A, Gómez-Posada JC, Gomis-Perez C, Fernández-Orth J, Malo C, Villarroel A. Lack of correlation between surface expression and currents in epileptogenic AB-calmodulin binding domain Kv7.2 potassium channel mutants. Channels (Austin) 2019; 12:299-310. [PMID: 30126342 PMCID: PMC6161613 DOI: 10.1080/19336950.2018.1511512] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Heteromers of Kv7.2/Kv7.3 subunits constitute the main substrate of the neuronal M-current that limits neuronal hyper-excitability and firing frequency. Calmodulin (CaM) binding is essential for surface expression of Kv7 channels, and disruption of this interaction leads to diseases ranging from mild epilepsy to early onset encephalopathy. In this study, we addressed the impact of a charge neutralizing mutation located at the periphery of helix B (K526N). We found that, CaM binding and surface expression was impaired, although current amplitude was not altered. Currents were reduced at a faster rate after activation of a voltage-dependent phosphatase, suggesting that phosphatidylinositol-4,5-bisphosphate (PIP2) binding was weaker. In contrast, a charge neutralizing mutation located at the periphery of helix A (R333Q) did not affect CaM binding, but impaired trafficking and led to a reduction in current amplitude. Taken together, these results suggest that disruption of CaM-dependent or CaM-independent trafficking of Kv7.2/Kv7.3 channels can lead to pathology regardless of the consequences on the macroscopic ionic flow through the channel.
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Affiliation(s)
- Alessandro Alaimo
- a Instituto Biofisika , Consejo Superior de Investigaciones Científicas, CSIC, UPV/EHU , Leioa , Spain
| | - Ainhoa Etxeberria
- a Instituto Biofisika , Consejo Superior de Investigaciones Científicas, CSIC, UPV/EHU , Leioa , Spain
| | - Juan Camilo Gómez-Posada
- a Instituto Biofisika , Consejo Superior de Investigaciones Científicas, CSIC, UPV/EHU , Leioa , Spain
| | - Carolina Gomis-Perez
- a Instituto Biofisika , Consejo Superior de Investigaciones Científicas, CSIC, UPV/EHU , Leioa , Spain
| | - Juncal Fernández-Orth
- a Instituto Biofisika , Consejo Superior de Investigaciones Científicas, CSIC, UPV/EHU , Leioa , Spain
| | - Covadonga Malo
- a Instituto Biofisika , Consejo Superior de Investigaciones Científicas, CSIC, UPV/EHU , Leioa , Spain
| | - Alvaro Villarroel
- a Instituto Biofisika , Consejo Superior de Investigaciones Científicas, CSIC, UPV/EHU , Leioa , Spain
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12
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Urrutia J, Aguado A, Muguruza-Montero A, Núñez E, Malo C, Casis O, Villarroel A. The Crossroad of Ion Channels and Calmodulin in Disease. Int J Mol Sci 2019; 20:ijms20020400. [PMID: 30669290 PMCID: PMC6359610 DOI: 10.3390/ijms20020400] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Revised: 01/11/2019] [Accepted: 01/16/2019] [Indexed: 01/21/2023] Open
Abstract
Calmodulin (CaM) is the principal Ca2+ sensor in eukaryotic cells, orchestrating the activity of hundreds of proteins. Disease causing mutations at any of the three genes that encode identical CaM proteins lead to major cardiac dysfunction, revealing the importance in the regulation of excitability. In turn, some mutations at the CaM binding site of ion channels cause similar diseases. Here we provide a summary of the two sides of the partnership between CaM and ion channels, describing the diversity of consequences of mutations at the complementary CaM binding domains.
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Affiliation(s)
- Janire Urrutia
- Biofisika Institute (CSIC, UPV/EHU), University of the Basque Country, 48940 Leioa, Spain.
| | - Alejandra Aguado
- Biofisika Institute (CSIC, UPV/EHU), University of the Basque Country, 48940 Leioa, Spain.
| | | | - Eider Núñez
- Biofisika Institute (CSIC, UPV/EHU), University of the Basque Country, 48940 Leioa, Spain.
| | - Covadonga Malo
- Biofisika Institute (CSIC, UPV/EHU), University of the Basque Country, 48940 Leioa, Spain.
| | - Oscar Casis
- Departamento de Fisiología, Facultad de Farmacia, Universidad del País Vasco (UPV/EHU), 01006 Vitoria-Gasteiz, Spain.
| | - Alvaro Villarroel
- Biofisika Institute (CSIC, UPV/EHU), University of the Basque Country, 48940 Leioa, Spain.
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13
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Gomis-Pérez C, Urrutia J, Marcé-Grau A, Malo C, López-Laso E, Felipe-Rucián A, Raspall-Chaure M, Macaya A, Villarroel A. Homomeric Kv7.2 current suppression is a common feature in KCNQ2 epileptic encephalopathy. Epilepsia 2018; 60:139-148. [PMID: 30478917 DOI: 10.1111/epi.14609] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [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: 01/17/2018] [Revised: 10/29/2018] [Accepted: 10/29/2018] [Indexed: 01/15/2023]
Abstract
OBJECTIVE To gain insight into the mechanisms underlying KCNQ2 encephalopathy by examining the electrophysiologic properties of mutant Kv7.2 channels in different multimeric configurations. METHODS We analyzed the genotype-phenotype relationship in 4 patients with KCNQ2 encephalopathy and performed electrophysiologic analysis of M-currents mediated by homomeric Kv7.2 or heteromeric Kv7.2/Kv7.3 channels. RESULTS Negligible or no current was recorded in cells expressing homomeric E130K, W270R, or G281R de novo mutants, and it was reduced by more than 90% for the L243F maternally inherited mutant. The E130K and G281R mutants presented a marked dominant-negative behavior, whereas the current density was partially reduced (L243F) or not affected (W270R) when coexpressed with wild-type Kv7.2 subunits. In contrast, the extent of Kv7.3 "rescue," which yields negligible currents on its own, followed the sequence E130K > L243F > W270R, whereas no rescue was observed with the G281R mutant. No significant effects on current density were observed when subunits were expressed in a 0.5:0.5:1.0 (Kv7.2:mutant:Kv7.3) DNA ratio to mimic the genetic balance. There was an increase in sensitivity to phosphatidylinositol 4,5-bisphosphate (PIP2 ) depletion for W270R/Kv7.3, but no substantial differences were observed when the mutated subunits were coexpressed with Kv7.2 or both Kv7.2 and Kv7.3. SIGNIFICANCE There was a marked disparity of the impact of these mutations on Kv7.2 function, which varied on association with Kv7.2 or Kv7.3 subunits. Current density of homomeric channels was the most reliable property relating Kv7.2 function to encephalopathy, but other factors are required to explain the milder phenotype for some individuals carrying the maternally inherited L243F mutation. We hypothesize that the role of homomeric Kv7.2 channels for fine-tuning neuronal connections during development is critical for the severity of the KCNQ2 encephalopathy.
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Affiliation(s)
- Carolina Gomis-Pérez
- Biofisika Institute, The Spanish National Research Council/University of the Basque Country, Leioa, Spain
| | - Janire Urrutia
- Biofisika Institute, The Spanish National Research Council/University of the Basque Country, Leioa, Spain
| | - Anna Marcé-Grau
- Pediatric Neurology Research Group, Vall d'Hebron Research Institute, Autonomous University of Barcelona, Barcelona, Spain
| | - Covadonga Malo
- Biofisika Institute, The Spanish National Research Council/University of the Basque Country, Leioa, Spain
| | - Eduardo López-Laso
- Reina Sofia University Hospital, Maimónides Institute for Biomedical Research, IMIBIC, CIBERER-ISCIII, Córdoba, Spain
| | - Ana Felipe-Rucián
- Pediatric Neurology Research Group, Vall d'Hebron Research Institute, Autonomous University of Barcelona, Barcelona, Spain
| | - Miquel Raspall-Chaure
- Pediatric Neurology Research Group, Vall d'Hebron Research Institute, Autonomous University of Barcelona, Barcelona, Spain
| | - Alfons Macaya
- Pediatric Neurology Research Group, Vall d'Hebron Research Institute, Autonomous University of Barcelona, Barcelona, Spain
| | - Alvaro Villarroel
- Biofisika Institute, The Spanish National Research Council/University of the Basque Country, Leioa, Spain
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14
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Alaimo A, Nuñez E, Aivar P, Fernández-Orth J, Gomis-Perez C, Bernardo-Seisdedos G, Malo C, Villarroel A. Calmodulin confers calcium sensitivity to the stability of the distal intracellular assembly domain of Kv7.2 channels. Sci Rep 2017; 7:13425. [PMID: 29044210 PMCID: PMC5647379 DOI: 10.1038/s41598-017-13811-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Accepted: 09/29/2017] [Indexed: 01/03/2023] Open
Abstract
Tetrameric coiled-coil structures are present in many ion channels, often adjacent to a calmodulin (CaM) binding site, although the relationship between the two is not completely understood. Here we examine the dynamic properties of the ABCD domain located in the intracellular C-terminus of tetrameric, voltage-dependent, potassium selective Kv7.2 channels. This domain encompasses the CaM binding site formed by helices A and B, followed by helix C, which is linked to the helix D coiled-coil. The data reveals that helix D stabilizes CaM binding, promoting trans-binding (CaM embracing neighboring subunits), and they suggest that the ABCD domain can be exchanged between subunits of the tetramer. Exchange is faster when mutations in AB weaken the CaM interaction. The exchange of ABCD domains is slower in the presence of Ca2+, indicating that CaM stabilization of the tetrameric assembly is enhanced when loaded with this cation. Our observations are consistent with a model that involves a dynamic mechanism of helix D assembly, which supports reciprocal allosteric coupling between the A-B module and the coiled-coil formed by the helix D. Thus, formation of the distal helix D tetramer influences CaM binding and CaM-dependent Kv7.2 properties, whereas reciprocally, CaM and Ca2+ influence the dynamic behavior of the helix D coiled-coil.
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Affiliation(s)
- Alessandro Alaimo
- Instituto Biofisika, Consejo Superior de Investigaciones Científicas, CSIC, UPV/EHU, Barrio Sarriena s/n, 48940, Leioa, Spain
| | - Eider Nuñez
- Instituto Biofisika, Consejo Superior de Investigaciones Científicas, CSIC, UPV/EHU, Barrio Sarriena s/n, 48940, Leioa, Spain
| | - Paloma Aivar
- Instituto Biofisika, Consejo Superior de Investigaciones Científicas, CSIC, UPV/EHU, Barrio Sarriena s/n, 48940, Leioa, Spain
| | - Juncal Fernández-Orth
- Instituto Biofisika, Consejo Superior de Investigaciones Científicas, CSIC, UPV/EHU, Barrio Sarriena s/n, 48940, Leioa, Spain
| | - Carolina Gomis-Perez
- Instituto Biofisika, Consejo Superior de Investigaciones Científicas, CSIC, UPV/EHU, Barrio Sarriena s/n, 48940, Leioa, Spain
| | - Ganeko Bernardo-Seisdedos
- Instituto Biofisika, Consejo Superior de Investigaciones Científicas, CSIC, UPV/EHU, Barrio Sarriena s/n, 48940, Leioa, Spain
| | - Covadonga Malo
- Instituto Biofisika, Consejo Superior de Investigaciones Científicas, CSIC, UPV/EHU, Barrio Sarriena s/n, 48940, Leioa, Spain
| | - Alvaro Villarroel
- Instituto Biofisika, Consejo Superior de Investigaciones Científicas, CSIC, UPV/EHU, Barrio Sarriena s/n, 48940, Leioa, Spain.
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15
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Gomis-Perez C, Soldovieri MV, Malo C, Ambrosino P, Taglialatela M, Areso P, Villarroel A. Differential Regulation of PI(4,5)P 2 Sensitivity of Kv7.2 and Kv7.3 Channels by Calmodulin. Front Mol Neurosci 2017; 10:117. [PMID: 28507506 PMCID: PMC5410570 DOI: 10.3389/fnmol.2017.00117] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [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: 01/19/2017] [Accepted: 04/10/2017] [Indexed: 11/19/2022] Open
Abstract
HIGHLIGHTS- Calmodulin-dependent Kv7.2 current density without the need of binding calcium. - Kv7.2 current density increase is accompanied with resistance to PI(4,5)P2 depletion. - Kv7.3 current density is insensitive to calmodulin elevation. - Kv7.3 is more sensitive to PI(4,5)P2 depletion in the presence of calmodulin. - Apo-calmodulin influences PI(4,5)P2 dependence in a subunit specific manner.
The identification and understanding of critical factors regulating M-current functional density, whose main components are Kv7.2 and Kv7.3 subunits, has profound pathophysiological impact given the important role of the M-current in neuronal excitability control. We report the increase in current density of Kv7.2 channels by calmodulin (CaM) and by a mutant CaM unable to bind Ca2+ (CaM1234) revealing that this potentiation is calcium independent. Furthermore, after co-expressing a CaM binding protein (CaM sponge) to reduce CaM cellular availability, Kv7.2 current density was reduced. Current inhibition after transient depletion of the essential Kv7 co-factor phosphatidylinositol-4,5-bisphosphate (PI(4,5)P2) by activating Danio rerio voltage sensitive phosphatase (DrVSP) was blunted by co-expressing CaM1234 or the CaM sponge. In addition, CaM-dependent potentiation was occluded by tonic elevation of PI(4,5)P2 levels by PI(4)P5-kinase (PIP5K) expression. In contrast to the effect on homomeric Kv7.2 channels, CaM1234 failed to potentiate heteromeric Kv7.2/3 or homomeric Kv7.3 channels. Sensitivity to PI(4,5)P2 depletion of Kv7.2/3 channels was increased after expression of CaM1234 or the CaM sponge, while that of homomeric Kv7.3 was unaltered. Altogether, the data reveal that apo-CaM influences PI(4,5)P2 dependence of Kv7.2, Kv7.2/3, and of Kv7.3 channels in a subunit specific manner.
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Affiliation(s)
- Carolina Gomis-Perez
- Biofisika Institutua, Consejo Superior de Investigaciones Científicas, CSIC, UPV/EHULeioa, Spain
| | - Maria V Soldovieri
- Department of Medicine and Health Science, University of MoliseCampobasso, Italy
| | - Covadonga Malo
- Biofisika Institutua, Consejo Superior de Investigaciones Científicas, CSIC, UPV/EHULeioa, Spain
| | - Paolo Ambrosino
- Department of Medicine and Health Science, University of MoliseCampobasso, Italy
| | - Maurizio Taglialatela
- Department of Medicine and Health Science, University of MoliseCampobasso, Italy.,Department of Neuroscience, University of Naples "Federico II,"Naples, Italy
| | - Pilar Areso
- Department Farmacología, UPV/EHU, Universidad del País VascoLeioa, Spain
| | - Alvaro Villarroel
- Biofisika Institutua, Consejo Superior de Investigaciones Científicas, CSIC, UPV/EHULeioa, Spain
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Gomis-Perez C, Nunez-Viadero E, Bernardo-Seisdedos G, Malo C, Areso P, Villarroel A. Monitoring Structural Reorganization of Calmodulin in Complex with the C-Terminus of KCNQ Channels. Biophys J 2017. [DOI: 10.1016/j.bpj.2016.11.620] [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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17
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Villarroel A, Bernardo-Seisdedos G, Alaimo A, Gomis-Perez C, Alberdi A, Malo C, Areso P, Millet O. Structural Insights of the Calcium Mediated Reorganization of the Calmodulin/Kv7.2 Channel Complex. Biophys J 2016. [DOI: 10.1016/j.bpj.2015.11.608] [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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18
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Alberdi A, Gomis-Perez C, Bernardo-Seisdedos G, Alaimo A, Malo C, Aldaregia J, Lopez-Robles C, Areso P, Butz E, Wahl-Schott C, Villarroel A. Uncoupling PIP2-calmodulin regulation of Kv7.2 channels by an assembly destabilizing epileptogenic mutation. J Cell Sci 2015; 128:4014-23. [PMID: 26359296 DOI: 10.1242/jcs.176420] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [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: 06/24/2015] [Accepted: 09/09/2015] [Indexed: 01/15/2023] Open
Abstract
We show that the combination of an intracellular bi-partite calmodulin (CaM)-binding site and a distant assembly region affect how an ion channel is regulated by a membrane lipid. Our data reveal that regulation by phosphatidylinositol(4,5)bisphosphate (PIP2) and stabilization of assembled Kv7.2 subunits by intracellular coiled-coil regions far from the membrane are coupled molecular processes. Live-cell fluorescence energy transfer measurements and direct binding studies indicate that remote coiled-coil formation creates conditions for different CaM interaction modes, each conferring different PIP2 dependency to Kv7.2 channels. Disruption of coiled-coil formation by epilepsy-causing mutation decreases apparent CaM-binding affinity and interrupts CaM influence on PIP2 sensitivity.
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Affiliation(s)
- Araitz Alberdi
- Unidad de Biofísica, Consejo Superior de Investigaciones Científicas, CSIC, UPV/EHU, Barrio Sarriena s/n, Leioa 48940, Spain
| | - Carolina Gomis-Perez
- Unidad de Biofísica, Consejo Superior de Investigaciones Científicas, CSIC, UPV/EHU, Barrio Sarriena s/n, Leioa 48940, Spain
| | - Ganeko Bernardo-Seisdedos
- Unidad de Biofísica, Consejo Superior de Investigaciones Científicas, CSIC, UPV/EHU, Barrio Sarriena s/n, Leioa 48940, Spain
| | - Alessandro Alaimo
- Unidad de Biofísica, Consejo Superior de Investigaciones Científicas, CSIC, UPV/EHU, Barrio Sarriena s/n, Leioa 48940, Spain
| | - Covadonga Malo
- Unidad de Biofísica, Consejo Superior de Investigaciones Científicas, CSIC, UPV/EHU, Barrio Sarriena s/n, Leioa 48940, Spain
| | - Juncal Aldaregia
- Unidad de Biofísica, Consejo Superior de Investigaciones Científicas, CSIC, UPV/EHU, Barrio Sarriena s/n, Leioa 48940, Spain
| | - Carlos Lopez-Robles
- Unidad de Biofísica, Consejo Superior de Investigaciones Científicas, CSIC, UPV/EHU, Barrio Sarriena s/n, Leioa 48940, Spain
| | - Pilar Areso
- Departament de Farmacología, UPV/EHU, Universidad del País Vasco, Barrio Sarriena s/n, Leioa 48940, Spain
| | - Elisabeth Butz
- Department of Pharmacy, Center for Drug Research and Center for Integrated Protein Science Munich (CIPSM), Ludwig-Maximilians-Universität, München 81377, Germany
| | - Christian Wahl-Schott
- Department of Pharmacy, Center for Drug Research and Center for Integrated Protein Science Munich (CIPSM), Ludwig-Maximilians-Universität, München 81377, Germany
| | - Alvaro Villarroel
- Unidad de Biofísica, Consejo Superior de Investigaciones Científicas, CSIC, UPV/EHU, Barrio Sarriena s/n, Leioa 48940, Spain
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19
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Gomis-Perez C, Alaimo A, Fernandez-Orth J, Alberdi A, Aivar-Mateo P, Bernardo-Seisdedos G, Malo C, Areso P, Felipe A, Villarroel A. An unconventional calmodulin-anchoring site within the AB module of Kv7.2 channels. J Cell Sci 2015; 128:3155-63. [PMID: 26148514 DOI: 10.1242/jcs.174128] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [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: 05/11/2015] [Accepted: 06/23/2015] [Indexed: 11/20/2022] Open
Abstract
Calmodulin (CaM) binding to the AB module is crucial for multiple mechanisms governing the function of Kv7.2 (also known as KCNQ2) K(+) channel subunits, which mediate one of the main components of the non-inactivating K(+) M-current, a key controller of neuronal excitability. Structural analysis indicates that the CaM N-lobe engages with helix B, whereas the C-lobe anchors to the IQ site within helix A. Here, we report the identification of a new site between helices A and B that assists in CaM binding whose sequence is reminiscent of the TW helix within the CaM C-lobe anchoring site of SK2 K(+) channels (also known as KCNN2). Mutations that disrupt CaM binding within the TW site, helix B or helix A yield functional channels, whereas no function is observed when the TW site and helix A, or the TW site and helix B are mutated simultaneously. Our data indicate that the TW site is dispensable for function, contributes to the stabilization of the CaM-Kv7.2 complex and becomes essential when docking to either helix A or when helix B is perturbed.
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Affiliation(s)
- Carolina Gomis-Perez
- Unidad de Biofísica, Consejo Superior de Investigaciones Científicas, CSIC, UPV/EHU, Universidad del País Vasco, Barrio Sarriena s/n, Leioa 48940, Spain
| | - Alessandro Alaimo
- Unidad de Biofísica, Consejo Superior de Investigaciones Científicas, CSIC, UPV/EHU, Universidad del País Vasco, Barrio Sarriena s/n, Leioa 48940, Spain
| | - Juncal Fernandez-Orth
- Unidad de Biofísica, Consejo Superior de Investigaciones Científicas, CSIC, UPV/EHU, Universidad del País Vasco, Barrio Sarriena s/n, Leioa 48940, Spain
| | - Araitz Alberdi
- Unidad de Biofísica, Consejo Superior de Investigaciones Científicas, CSIC, UPV/EHU, Universidad del País Vasco, Barrio Sarriena s/n, Leioa 48940, Spain
| | - Paloma Aivar-Mateo
- Unidad de Biofísica, Consejo Superior de Investigaciones Científicas, CSIC, UPV/EHU, Universidad del País Vasco, Barrio Sarriena s/n, Leioa 48940, Spain
| | - Ganeko Bernardo-Seisdedos
- Unidad de Biofísica, Consejo Superior de Investigaciones Científicas, CSIC, UPV/EHU, Universidad del País Vasco, Barrio Sarriena s/n, Leioa 48940, Spain
| | - Covadonga Malo
- Unidad de Biofísica, Consejo Superior de Investigaciones Científicas, CSIC, UPV/EHU, Universidad del País Vasco, Barrio Sarriena s/n, Leioa 48940, Spain
| | - Pilar Areso
- Dept. Farmacología, UPV/EHU, Universidad del País Vasco, Barrio Sarriena s/n, Leioa 48940, Spain
| | - Antonio Felipe
- Molecular Physiology Laboratory, Departament de Bioquímica i Biologia Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, 08028 Barcelona, Spain
| | - Alvaro Villarroel
- Unidad de Biofísica, Consejo Superior de Investigaciones Científicas, CSIC, UPV/EHU, Universidad del País Vasco, Barrio Sarriena s/n, Leioa 48940, Spain
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Gomis-Perez C, Soldovieri MV, Alberdi A, Ambrosino P, Di Maria M, Alaimo A, Bernardo-Seisdedos G, Malo C, Areso P, Taglialatela M, Villarroel A. PIP2 and Surface Expression Underlie Apo-Calmodulin Dependent Kv7.2/KCNQ2 Current Potentiation. Biophys J 2015. [DOI: 10.1016/j.bpj.2014.11.1910] [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: 11/24/2022] Open
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Oliveras A, Roura-Ferrer M, Solé L, de la Cruz A, Prieto A, Etxebarria A, Manils J, Morales-Cano D, Condom E, Soler C, Cogolludo A, Valenzuela C, Villarroel A, Comes N, Felipe A. Functional assembly of Kv7.1/Kv7.5 channels with emerging properties on vascular muscle physiology. Arterioscler Thromb Vasc Biol 2014; 34:1522-30. [PMID: 24855057 DOI: 10.1161/atvbaha.114.303801] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE Voltage-dependent K(+) (Kv) channels from the Kv7 family are expressed in blood vessels and contribute to cardiovascular physiology. Although Kv7 channel blockers trigger muscle contractions, Kv7 activators act as vasorelaxants. Kv7.1 and Kv7.5 are expressed in many vessels. Kv7.1 is under intense investigation because Kv7.1 blockers fail to modulate smooth muscle reactivity. In this study, we analyzed whether Kv7.1 and Kv7.5 may form functional heterotetrameric channels increasing the channel diversity in vascular smooth muscles. APPROACH AND RESULTS Kv7.1 and Kv7.5 currents elicited in arterial myocytes, oocyte, and mammalian expression systems suggest the formation of heterotetrameric complexes. Kv7.1/Kv7.5 heteromers, exhibiting different pharmacological characteristics, participate in the arterial tone. Kv7.1/Kv7.5 associations were confirmed by coimmunoprecipitation, fluorescence resonance energy transfer, and fluorescence recovery after photobleaching experiments. Kv7.1/Kv7.5 heterotetramers were highly retained at the endoplasmic reticulum. Studies in HEK-293 cells, heart, brain, and smooth and skeletal muscles demonstrated that the predominant presence of Kv7.5 stimulates release of Kv7.1/Kv7.5 oligomers out of lipid raft microdomains. Electrophysiological studies supported that KCNE1 and KCNE3 regulatory subunits further increased the channel diversity. Finally, the analysis of rat isolated myocytes and human blood vessels demonstrated that Kv7.1 and Kv7.5 exhibited a differential expression, which may lead to channel diversity. CONCLUSIONS Kv7.1 and Kv7.5 form heterotetrameric channels increasing the diversity of structures which fine-tune blood vessel reactivity. Because the lipid raft localization of ion channels is crucial for cardiovascular physiology, Kv7.1/Kv7.5 heteromers provide efficient spatial and temporal regulation of smooth muscle function. Our results shed light on the debate about the contribution of Kv7 channels to vasoconstriction and hypertension.
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Affiliation(s)
- Anna Oliveras
- From the Molecular Physiology Laboratory, Departament de Bioquímica i Biologia Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Barcelona, Spain (A.O., M.R.-F., L.S., N.C., A.F.); Unidad de Biofísica, CSIC-UPV/EHU, Universidad del País Vasco, País Vasco, Spain (M.R.-F., A.E., A.V.); Instituto de Investigaciones Biomédicas "Alberto Sols" CSIC-Universidad Autónoma de Madrid, Madrid, Spain (A.d.l.C., A.P., C.V.); Departament de Patologia i Terapèutica Experimental, Hospital Universitari de Bellvitge-Universitat de Barcelona, Barcelona, Spain (J.M., E.C., C.S.); and Departamento de Farmacología, Universidad Complutense de Madrid, Ciber Enfermedades Respiratorias (CibeRes), Madrid, Spain (A.C., D.M.-C.)
| | - Meritxell Roura-Ferrer
- From the Molecular Physiology Laboratory, Departament de Bioquímica i Biologia Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Barcelona, Spain (A.O., M.R.-F., L.S., N.C., A.F.); Unidad de Biofísica, CSIC-UPV/EHU, Universidad del País Vasco, País Vasco, Spain (M.R.-F., A.E., A.V.); Instituto de Investigaciones Biomédicas "Alberto Sols" CSIC-Universidad Autónoma de Madrid, Madrid, Spain (A.d.l.C., A.P., C.V.); Departament de Patologia i Terapèutica Experimental, Hospital Universitari de Bellvitge-Universitat de Barcelona, Barcelona, Spain (J.M., E.C., C.S.); and Departamento de Farmacología, Universidad Complutense de Madrid, Ciber Enfermedades Respiratorias (CibeRes), Madrid, Spain (A.C., D.M.-C.)
| | - Laura Solé
- From the Molecular Physiology Laboratory, Departament de Bioquímica i Biologia Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Barcelona, Spain (A.O., M.R.-F., L.S., N.C., A.F.); Unidad de Biofísica, CSIC-UPV/EHU, Universidad del País Vasco, País Vasco, Spain (M.R.-F., A.E., A.V.); Instituto de Investigaciones Biomédicas "Alberto Sols" CSIC-Universidad Autónoma de Madrid, Madrid, Spain (A.d.l.C., A.P., C.V.); Departament de Patologia i Terapèutica Experimental, Hospital Universitari de Bellvitge-Universitat de Barcelona, Barcelona, Spain (J.M., E.C., C.S.); and Departamento de Farmacología, Universidad Complutense de Madrid, Ciber Enfermedades Respiratorias (CibeRes), Madrid, Spain (A.C., D.M.-C.)
| | - Alicia de la Cruz
- From the Molecular Physiology Laboratory, Departament de Bioquímica i Biologia Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Barcelona, Spain (A.O., M.R.-F., L.S., N.C., A.F.); Unidad de Biofísica, CSIC-UPV/EHU, Universidad del País Vasco, País Vasco, Spain (M.R.-F., A.E., A.V.); Instituto de Investigaciones Biomédicas "Alberto Sols" CSIC-Universidad Autónoma de Madrid, Madrid, Spain (A.d.l.C., A.P., C.V.); Departament de Patologia i Terapèutica Experimental, Hospital Universitari de Bellvitge-Universitat de Barcelona, Barcelona, Spain (J.M., E.C., C.S.); and Departamento de Farmacología, Universidad Complutense de Madrid, Ciber Enfermedades Respiratorias (CibeRes), Madrid, Spain (A.C., D.M.-C.)
| | - Angela Prieto
- From the Molecular Physiology Laboratory, Departament de Bioquímica i Biologia Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Barcelona, Spain (A.O., M.R.-F., L.S., N.C., A.F.); Unidad de Biofísica, CSIC-UPV/EHU, Universidad del País Vasco, País Vasco, Spain (M.R.-F., A.E., A.V.); Instituto de Investigaciones Biomédicas "Alberto Sols" CSIC-Universidad Autónoma de Madrid, Madrid, Spain (A.d.l.C., A.P., C.V.); Departament de Patologia i Terapèutica Experimental, Hospital Universitari de Bellvitge-Universitat de Barcelona, Barcelona, Spain (J.M., E.C., C.S.); and Departamento de Farmacología, Universidad Complutense de Madrid, Ciber Enfermedades Respiratorias (CibeRes), Madrid, Spain (A.C., D.M.-C.)
| | - Ainhoa Etxebarria
- From the Molecular Physiology Laboratory, Departament de Bioquímica i Biologia Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Barcelona, Spain (A.O., M.R.-F., L.S., N.C., A.F.); Unidad de Biofísica, CSIC-UPV/EHU, Universidad del País Vasco, País Vasco, Spain (M.R.-F., A.E., A.V.); Instituto de Investigaciones Biomédicas "Alberto Sols" CSIC-Universidad Autónoma de Madrid, Madrid, Spain (A.d.l.C., A.P., C.V.); Departament de Patologia i Terapèutica Experimental, Hospital Universitari de Bellvitge-Universitat de Barcelona, Barcelona, Spain (J.M., E.C., C.S.); and Departamento de Farmacología, Universidad Complutense de Madrid, Ciber Enfermedades Respiratorias (CibeRes), Madrid, Spain (A.C., D.M.-C.)
| | - Joan Manils
- From the Molecular Physiology Laboratory, Departament de Bioquímica i Biologia Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Barcelona, Spain (A.O., M.R.-F., L.S., N.C., A.F.); Unidad de Biofísica, CSIC-UPV/EHU, Universidad del País Vasco, País Vasco, Spain (M.R.-F., A.E., A.V.); Instituto de Investigaciones Biomédicas "Alberto Sols" CSIC-Universidad Autónoma de Madrid, Madrid, Spain (A.d.l.C., A.P., C.V.); Departament de Patologia i Terapèutica Experimental, Hospital Universitari de Bellvitge-Universitat de Barcelona, Barcelona, Spain (J.M., E.C., C.S.); and Departamento de Farmacología, Universidad Complutense de Madrid, Ciber Enfermedades Respiratorias (CibeRes), Madrid, Spain (A.C., D.M.-C.)
| | - Daniel Morales-Cano
- From the Molecular Physiology Laboratory, Departament de Bioquímica i Biologia Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Barcelona, Spain (A.O., M.R.-F., L.S., N.C., A.F.); Unidad de Biofísica, CSIC-UPV/EHU, Universidad del País Vasco, País Vasco, Spain (M.R.-F., A.E., A.V.); Instituto de Investigaciones Biomédicas "Alberto Sols" CSIC-Universidad Autónoma de Madrid, Madrid, Spain (A.d.l.C., A.P., C.V.); Departament de Patologia i Terapèutica Experimental, Hospital Universitari de Bellvitge-Universitat de Barcelona, Barcelona, Spain (J.M., E.C., C.S.); and Departamento de Farmacología, Universidad Complutense de Madrid, Ciber Enfermedades Respiratorias (CibeRes), Madrid, Spain (A.C., D.M.-C.)
| | - Enric Condom
- From the Molecular Physiology Laboratory, Departament de Bioquímica i Biologia Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Barcelona, Spain (A.O., M.R.-F., L.S., N.C., A.F.); Unidad de Biofísica, CSIC-UPV/EHU, Universidad del País Vasco, País Vasco, Spain (M.R.-F., A.E., A.V.); Instituto de Investigaciones Biomédicas "Alberto Sols" CSIC-Universidad Autónoma de Madrid, Madrid, Spain (A.d.l.C., A.P., C.V.); Departament de Patologia i Terapèutica Experimental, Hospital Universitari de Bellvitge-Universitat de Barcelona, Barcelona, Spain (J.M., E.C., C.S.); and Departamento de Farmacología, Universidad Complutense de Madrid, Ciber Enfermedades Respiratorias (CibeRes), Madrid, Spain (A.C., D.M.-C.)
| | - Concepció Soler
- From the Molecular Physiology Laboratory, Departament de Bioquímica i Biologia Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Barcelona, Spain (A.O., M.R.-F., L.S., N.C., A.F.); Unidad de Biofísica, CSIC-UPV/EHU, Universidad del País Vasco, País Vasco, Spain (M.R.-F., A.E., A.V.); Instituto de Investigaciones Biomédicas "Alberto Sols" CSIC-Universidad Autónoma de Madrid, Madrid, Spain (A.d.l.C., A.P., C.V.); Departament de Patologia i Terapèutica Experimental, Hospital Universitari de Bellvitge-Universitat de Barcelona, Barcelona, Spain (J.M., E.C., C.S.); and Departamento de Farmacología, Universidad Complutense de Madrid, Ciber Enfermedades Respiratorias (CibeRes), Madrid, Spain (A.C., D.M.-C.)
| | - Angel Cogolludo
- From the Molecular Physiology Laboratory, Departament de Bioquímica i Biologia Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Barcelona, Spain (A.O., M.R.-F., L.S., N.C., A.F.); Unidad de Biofísica, CSIC-UPV/EHU, Universidad del País Vasco, País Vasco, Spain (M.R.-F., A.E., A.V.); Instituto de Investigaciones Biomédicas "Alberto Sols" CSIC-Universidad Autónoma de Madrid, Madrid, Spain (A.d.l.C., A.P., C.V.); Departament de Patologia i Terapèutica Experimental, Hospital Universitari de Bellvitge-Universitat de Barcelona, Barcelona, Spain (J.M., E.C., C.S.); and Departamento de Farmacología, Universidad Complutense de Madrid, Ciber Enfermedades Respiratorias (CibeRes), Madrid, Spain (A.C., D.M.-C.)
| | - Carmen Valenzuela
- From the Molecular Physiology Laboratory, Departament de Bioquímica i Biologia Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Barcelona, Spain (A.O., M.R.-F., L.S., N.C., A.F.); Unidad de Biofísica, CSIC-UPV/EHU, Universidad del País Vasco, País Vasco, Spain (M.R.-F., A.E., A.V.); Instituto de Investigaciones Biomédicas "Alberto Sols" CSIC-Universidad Autónoma de Madrid, Madrid, Spain (A.d.l.C., A.P., C.V.); Departament de Patologia i Terapèutica Experimental, Hospital Universitari de Bellvitge-Universitat de Barcelona, Barcelona, Spain (J.M., E.C., C.S.); and Departamento de Farmacología, Universidad Complutense de Madrid, Ciber Enfermedades Respiratorias (CibeRes), Madrid, Spain (A.C., D.M.-C.)
| | - Alvaro Villarroel
- From the Molecular Physiology Laboratory, Departament de Bioquímica i Biologia Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Barcelona, Spain (A.O., M.R.-F., L.S., N.C., A.F.); Unidad de Biofísica, CSIC-UPV/EHU, Universidad del País Vasco, País Vasco, Spain (M.R.-F., A.E., A.V.); Instituto de Investigaciones Biomédicas "Alberto Sols" CSIC-Universidad Autónoma de Madrid, Madrid, Spain (A.d.l.C., A.P., C.V.); Departament de Patologia i Terapèutica Experimental, Hospital Universitari de Bellvitge-Universitat de Barcelona, Barcelona, Spain (J.M., E.C., C.S.); and Departamento de Farmacología, Universidad Complutense de Madrid, Ciber Enfermedades Respiratorias (CibeRes), Madrid, Spain (A.C., D.M.-C.)
| | - Núria Comes
- From the Molecular Physiology Laboratory, Departament de Bioquímica i Biologia Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Barcelona, Spain (A.O., M.R.-F., L.S., N.C., A.F.); Unidad de Biofísica, CSIC-UPV/EHU, Universidad del País Vasco, País Vasco, Spain (M.R.-F., A.E., A.V.); Instituto de Investigaciones Biomédicas "Alberto Sols" CSIC-Universidad Autónoma de Madrid, Madrid, Spain (A.d.l.C., A.P., C.V.); Departament de Patologia i Terapèutica Experimental, Hospital Universitari de Bellvitge-Universitat de Barcelona, Barcelona, Spain (J.M., E.C., C.S.); and Departamento de Farmacología, Universidad Complutense de Madrid, Ciber Enfermedades Respiratorias (CibeRes), Madrid, Spain (A.C., D.M.-C.)
| | - Antonio Felipe
- From the Molecular Physiology Laboratory, Departament de Bioquímica i Biologia Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Barcelona, Spain (A.O., M.R.-F., L.S., N.C., A.F.); Unidad de Biofísica, CSIC-UPV/EHU, Universidad del País Vasco, País Vasco, Spain (M.R.-F., A.E., A.V.); Instituto de Investigaciones Biomédicas "Alberto Sols" CSIC-Universidad Autónoma de Madrid, Madrid, Spain (A.d.l.C., A.P., C.V.); Departament de Patologia i Terapèutica Experimental, Hospital Universitari de Bellvitge-Universitat de Barcelona, Barcelona, Spain (J.M., E.C., C.S.); and Departamento de Farmacología, Universidad Complutense de Madrid, Ciber Enfermedades Respiratorias (CibeRes), Madrid, Spain (A.C., D.M.-C.).
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Alaimo A, Alberdi A, Gomis-Perez C, Fernández-Orth J, Bernardo-Seisdedos G, Malo C, Millet O, Areso P, Villarroel A. Pivoting between calmodulin lobes triggered by calcium in the Kv7.2/calmodulin complex. PLoS One 2014; 9:e86711. [PMID: 24489773 PMCID: PMC3904923 DOI: 10.1371/journal.pone.0086711] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [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: 10/01/2013] [Accepted: 12/12/2013] [Indexed: 11/25/2022] Open
Abstract
Kv7.2 (KCNQ2) is the principal molecular component of the slow voltage gated M-channel, which strongly influences neuronal excitability. Calmodulin (CaM) binds to two intracellular C-terminal segments of Kv7.2 channels, helices A and B, and it is required for exit from the endoplasmic reticulum. However, the molecular mechanisms by which CaM controls channel trafficking are currently unknown. Here we used two complementary approaches to explore the molecular events underlying the association between CaM and Kv7.2 and their regulation by Ca2+. First, we performed a fluorometric assay using dansylated calmodulin (D-CaM) to characterize the interaction of its individual lobes to the Kv7.2 CaM binding site (Q2AB). Second, we explored the association of Q2AB with CaM by NMR spectroscopy, using 15N-labeled CaM as a reporter. The combined data highlight the interdependency of the N- and C-lobes of CaM in the interaction with Q2AB, suggesting that when CaM binds Ca2+ the binding interface pivots between the N-lobe whose interactions are dominated by helix B and the C-lobe where the predominant interaction is with helix A. In addition, Ca2+ makes CaM binding to Q2AB more difficult and, reciprocally, the channel weakens the association of CaM with Ca2+.
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Affiliation(s)
- Alessandro Alaimo
- Unidad de Biofísica, CSIC, UPV/EHU, Universidad del País Vasco, Leioa, Spain
| | - Araitz Alberdi
- Unidad de Biofísica, CSIC, UPV/EHU, Universidad del País Vasco, Leioa, Spain
| | | | | | | | - Covadonga Malo
- Unidad de Biofísica, CSIC, UPV/EHU, Universidad del País Vasco, Leioa, Spain
| | - Oscar Millet
- Structural Biology Unit, CICbioGUNE, Bizkaia Technology Park, Derio, Spain
| | - Pilar Areso
- Departamento de Farmacología, UPV/EHU, Universidad del País Vasco, Leioa, Spain
| | - Alvaro Villarroel
- Unidad de Biofísica, CSIC, UPV/EHU, Universidad del País Vasco, Leioa, Spain
- * E-mail:
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Bonache MA, Alaimo A, Malo C, Millet O, Villarroel A, González-Muñiz R. Clicked bis-PEG-peptide conjugates for studying calmodulin-Kv7.2 channel binding. Org Biomol Chem 2014; 12:8877-87. [DOI: 10.1039/c4ob01338g] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Small bis-conjugates helix A329–350-PEG-triazole-PEG-helix B508–526 (41 residues), prepared through click chemistry of PEGylated peptide derivatives, bind to CaM with nanomolar affinity, behaving as mimics of the Kv7.2 native fragment (239 residues).
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Affiliation(s)
| | - Alessandro Alaimo
- Unidad de Biofísica
- CSIC-UPV/EHU
- Universidad de País Vasco
- 48940 Leioa, Spain
| | - Covadonga Malo
- Unidad de Biofísica
- CSIC-UPV/EHU
- Universidad de País Vasco
- 48940 Leioa, Spain
| | - Oscar Millet
- Structural Biology Unit
- CICbioGUNE
- 48160 Derio, Spain
| | - Alvaro Villarroel
- Unidad de Biofísica
- CSIC-UPV/EHU
- Universidad de País Vasco
- 48940 Leioa, Spain
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Gomis-Perez C, Soldovieri V, Alberdi A, Ambrosino P, Alaimo A, Bernardo-Seisdedos G, Areso P, Taglialatela M, Villarroel A. Calcium-Independent Potentation of Kv7.2 Current Density by Calmodulin. Biophys J 2014. [DOI: 10.1016/j.bpj.2013.11.822] [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: 12/01/2022] Open
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De los Reyes M, Palomino J, Jofré S, Villarroel A, Moreno R. Golgi apparatus and endoplasmic reticulum dynamic during meiotic development in canine oocytes. Reprod Domest Anim 2013; 47 Suppl 6:93-7. [PMID: 23279474 DOI: 10.1111/rda.12014] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Accepted: 06/20/2012] [Indexed: 11/29/2022]
Abstract
The Golgi apparatus (GA) and endoplasmic reticulum (ER) play a central role in the events related to intracellular trafficking distribution. This work evaluated the dynamics and localization of the GA and ER in canine oocytes during meiotic development in vitro. Cumulus-oocytes complexes (COCs) from ovaries of adult bitches were incubated for IVM for 0, 48, 72 and 96 h. At each time, the nuclear status was determined using DAPI staining, and the GA was evaluated by immunofluorescence using two antibodies against Golgi proteins: GM130 and Giantin. ER was analysed with fluorescent lipid probes (ER-Tracker), for living cells. Golgi structures were homogeneous in the cytoplasm in non-matured oocytes, mainly in those GV-arrested oocytes. In contrast, at 48 h and from GVBD stage, the immunolocalization began to be subcortical, increasing at 72 h and 96 h. Meiotic development increased with time and the majority of oocytes at MI-MII stages showed cortical distribution of Golgi structure. Living ZP intact non-matured oocytes showed a reticular pattern of ER that covered oocyte cortex. Confocal microscopy showed that, in all levels cuts the fluorescence marks were located in the cortical region, irrespective of culture time. The changes and localization in these organelles during IVM might be related to meiotic development, but in a non-synchronous manner.
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Affiliation(s)
- M De los Reyes
- Laboratory of Animal Reproduction, Faculty of Veterinary Sciences, University of Chile, Santiago, Chile.
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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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Abstract
Steady-state fluorescence spectroscopy is a biophysical technique widely employed to characterize -interactions between proteins in vitro. Only a few proteins naturally fluoresce in cells, but by covalently attaching fluorophores virtually all proteins can be monitored. One of the first extrinsic fluorescent probes to be developed, and that is still in use, is dansyl chloride. We have used this method to monitor the interaction of a variety of proteins, including ion channels, with the Ca(2+)-dependent regulatory protein calmodulin. Here we describe the preparation and use of dansyl-calmodulin (D-CaM).
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Affiliation(s)
- Alessandro Alaimo
- Unidad de Biofísica (CSIC-UPV/EHU), Universidad del País Vasco, Leioa, Spain
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Alaimo A, Alberdi A, Gomis-Perez C, Fernández-Orth J, Gómez-Posada JC, Areso P, Villarroel A. Cooperativity between calmodulin-binding sites in Kv7.2 channels. J Cell Sci 2012. [PMID: 23203804 DOI: 10.1242/jcs.114082] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Among the multiple roles assigned to calmodulin (CaM), controlling the surface expression of Kv7.2 channels by binding to two discontinuous sites is a unique property of this Ca(2+) binding protein. Mutations that interfere with CaM binding or the sequestering of CaM prevent this M-channel component from exiting the endoplasmic reticulum (ER), which reduces M-current density in hippocampal neurons, enhancing excitability and offering a rational mechanism to explain some forms of benign familial neonatal convulsions (BFNC). Previously, we identified a mutation (S511D) that impedes CaM binding while allowing the channel to exit the ER, hinting that CaM binding may not be strictly required for Kv7.2 channel trafficking to the plasma membrane. Alternatively, this interaction with CaM might escape detection and, indeed, we now show that the S511D mutant contains functional CaM-binding sites that are not detected by classical biochemical techniques. Surface expression and function is rescued by CaM, suggesting that free CaM in HEK293 cells is limiting and reinforcing the hypothesis that CaM binding is required for ER exit. Within the CaM-binding domain formed by two sites (helix A and helix B), we show that CaM binds to helix B with higher apparent affinity than helix A, both in the presence and absence of Ca(2+), and that the two sites cooperate. Hence, CaM can bridge two binding domains, anchoring helix A of one subunit to helix B of another subunit, in this way influencing the function of Kv7.2 channels.
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Affiliation(s)
- Alessandro Alaimo
- Unidad de Biofísica, CSIC-UPV/EHU, Universidad del País Vasco, Barrio Sarriena s/n, 48940 Leioa, Spain
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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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Stewart AP, Gómez-Posada JC, McGeorge J, Rouhani MJ, Villarroel A, Murrell-Lagnado RD, Edwardson JM. The Kv7.2/Kv7.3 heterotetramer assembles with a random subunit arrangement. J Biol Chem 2012; 287:11870-7. [PMID: 22334706 DOI: 10.1074/jbc.m111.336511] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Voltage-gated K(+) channels composed of Kv7.2 and Kv7.3 are the predominant contributors to the M-current, which plays a key role in controlling neuronal activity. Various lines of evidence have indicated that Kv7.2 and Kv7.3 form a heteromeric channel. However, the subunit stoichiometry and arrangement within this putative heteromer are so far unknown. Here, we have addressed this question using atomic force microscopy imaging of complexes between isolated Kv7.2/Kv7.3 channels and antibodies to epitope tags on the two subunits, Myc on Kv7.2 and HA on Kv7.3. Initially, tsA 201 cells were transiently transfected with equal amounts of cDNA for the two subunits. The heteromer was isolated through binding of either tag to immunoaffinity beads and then decorated with antibodies to the other tag. In both cases, the distribution of angles between pairs of bound antibodies had two peaks, at around 90° and around 180°, and in both cases the 90° peak was about double the size of the 180° peak. These results indicate that the Kv7.2/Kv7.3 heteromer generated by cells expressing approximately equal amounts of the two subunits assembles as a tetramer with a predominantly 2:2 subunit stoichiometry and with a random subunit arrangement. When the DNA ratio for the two subunits was varied, copurification experiments indicated that the subunit stoichiometry was variable and not fixed at 2:2. Hence, there are no constraints on either the subunit stoichiometry or the subunit arrangement.
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Affiliation(s)
- Andrew P Stewart
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, United Kingdom
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31
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Roura-Ferrer M, Solé L, Oliveras A, Villarroel A, Comes N, Felipe A. Targeting of Kv7.5 (KCNQ5)/KCNE channels to surface microdomains of cell membranes. Muscle Nerve 2012; 45:48-54. [PMID: 22190306 DOI: 10.1002/mus.22231] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
BACKGROUND Kv7.5 (KCNQ5) channels conduct M-type potassium currents in the brain, are expressed in skeletal muscle, and contribute to vascular muscle tone. METHODS We coexpressed Kv7.5 and KCNE1-3 peptides in HEK293 cells and then analyzed their association using electrophysiology and co-immunoprecipitation, assessed localization using confocal microscopy, examined targeting of the oligomeric channels to cholesterol-rich membrane surface microdomains using lipid raft isolation, and evaluated their membrane dynamics using fluorescence recovery after photobleaching (FRAP). RESULTS Kv7.5 forms oligomeric channels specifically with KCNE1 and KCNE3. The expression of Kv7.5 targeted to cholesterol-rich membrane surface microdomains was very low. Oligomeric Kv7.5/KCNE1 and Kv7.5/KCNE3 channels did not localize to lipid rafts. However, Kv7.5 association impaired KCNE3 expression in lipid raft microdomains. CONCLUSIONS Our results indicate that Kv7.5 contributes to the spatial regulation of KCNE3. This new scenario could greatly assist in determining the physiological relevance of putative KCNE3 interactions in nerve and muscle.
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Affiliation(s)
- Meritxell Roura-Ferrer
- Molecular Physiology Laboratory, Departament de Bioquímica i Biologia Molecular, Institut de Biomedicina, Universitat de Barcelona, Avenida Diagonal 645, E-08028 Barcelona, Spain
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Sole L, Roura-Ferrer M, Oliveras A, Vallejo A, Roig S, Villarroel A, Comes N, Felipe A. Selective Formation of Oligomeric Kv7.5 (KCNQ5)/KCNE1 and Kv7.5 (KCNQ5)/KCNE3 Channels. Differential Targeting to Membrane Surface Microdomains. Biophys J 2012. [DOI: 10.1016/j.bpj.2011.11.3688] [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: 10/14/2022] Open
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33
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Gómez-Posada JC, Aivar P, Alberdi A, Alaimo A, Etxeberría A, Fernández-Orth J, Zamalloa T, Roura-Ferrer M, Villace P, Areso P, Casis O, Villarroel A. Kv7 channels can function without constitutive calmodulin tethering. PLoS One 2011; 6:e25508. [PMID: 21980481 PMCID: PMC3182250 DOI: 10.1371/journal.pone.0025508] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [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: 05/25/2011] [Accepted: 09/05/2011] [Indexed: 11/19/2022] Open
Abstract
M-channels are voltage-gated potassium channels composed of Kv7.2-7.5 subunits that serve as important regulators of neuronal excitability. Calmodulin binding is required for Kv7 channel function and mutations in Kv7.2 that disrupt calmodulin binding cause Benign Familial Neonatal Convulsions (BFNC), a dominantly inherited human epilepsy. On the basis that Kv7.2 mutants deficient in calmodulin binding are not functional, calmodulin has been defined as an auxiliary subunit of Kv7 channels. However, we have identified a presumably phosphomimetic mutation S511D that permits calmodulin-independent function. Thus, our data reveal that constitutive tethering of calmodulin is not required for Kv7 channel function.
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Affiliation(s)
- Juan Camilo Gómez-Posada
- Unidad de Biofísica, Consejo Superior de Investigaciones Científicas-Universidad del País Vasco/Euskal Herriko Unibersitatea, Leioa, Spain
| | - Paloma Aivar
- Unidad de Biofísica, Consejo Superior de Investigaciones Científicas-Universidad del País Vasco/Euskal Herriko Unibersitatea, Leioa, Spain
| | - Araitz Alberdi
- Unidad de Biofísica, Consejo Superior de Investigaciones Científicas-Universidad del País Vasco/Euskal Herriko Unibersitatea, Leioa, Spain
| | - Alessandro Alaimo
- Unidad de Biofísica, Consejo Superior de Investigaciones Científicas-Universidad del País Vasco/Euskal Herriko Unibersitatea, Leioa, Spain
| | - Ainhoa Etxeberría
- Unidad de Biofísica, Consejo Superior de Investigaciones Científicas-Universidad del País Vasco/Euskal Herriko Unibersitatea, Leioa, Spain
| | - Juncal Fernández-Orth
- Unidad de Biofísica, Consejo Superior de Investigaciones Científicas-Universidad del País Vasco/Euskal Herriko Unibersitatea, Leioa, Spain
| | - Teresa Zamalloa
- Unidad de Biofísica, Consejo Superior de Investigaciones Científicas-Universidad del País Vasco/Euskal Herriko Unibersitatea, Leioa, Spain
| | - Meritxell Roura-Ferrer
- Unidad de Biofísica, Consejo Superior de Investigaciones Científicas-Universidad del País Vasco/Euskal Herriko Unibersitatea, Leioa, Spain
| | - Patricia Villace
- Unidad de Biofísica, Consejo Superior de Investigaciones Científicas-Universidad del País Vasco/Euskal Herriko Unibersitatea, Leioa, Spain
| | - Pilar Areso
- Dept. Farmacología, Universidad del País Vasco, Leioa, Spain
| | - Oscar Casis
- Dept. Fisiología, Universidad del País Vasco, Leioa, Spain
| | - Alvaro Villarroel
- Unidad de Biofísica, Consejo Superior de Investigaciones Científicas-Universidad del País Vasco/Euskal Herriko Unibersitatea, Leioa, Spain
- * E-mail:
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Abstract
The objectives of this study were to identify factors associated with zoonotic infections in veterinarians, the incidence of physician consultation and treatment and the incidence of diagnostic and treatment errors. Veterinarians in any area of practice were solicited to participate in an online survey through an invitation letter sent to the Oregon Veterinary Medical Association. Proportions of respondents to various factors were analyzed for differences among gender, age, time since graduation and type of practice in which they worked. In all, 216 complete responses were received. In all, 13.9% of respondents had never been vaccinated against rabies, and 20.8% had been exposed to suspect rabid animals, mostly (64.4%) a single time. Other zoonoses were reported by 47.2% of respondents: mostly diseases transmitted via contact (57.4%) especially ringworm, followed by those with oral transmission (21.7%). Most zoonotic infections were reportedly acquired by young veterinarians working in primary care veterinary practice. Cats were the species most commonly reported as the animal source of a zoonotic infection. Veterinarians likely self-diagnosed zoonotic diseases, especially those transmitted by contact. Medical care providers were consulted for diagnosis of more serious diseases. Diagnosis and treatment errors were uncommon. Results of this study emphasize the need to educate future veterinarians during their early years in veterinary school about the risks associated with their future jobs.
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Affiliation(s)
- J Jackson
- Department of Clinical Sciences, College of Veterinary Medicine, Oregon State University, Corvallis, OR 97331, USA.
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35
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Padilla-Parra S, las Heras GD, Fernandez-Orth J, Lopez-Fernandez S, Villarroel A, Requejo-Isidro J. Quantitative TCSPC FRET-FLIM Applied to Donors Exhibiting Multi-Exponential Decays: Spatio-Temporal Interaction Between Calmodulin and the Kv7.2 Potassium Channel in Living Cells. Biophys J 2011. [DOI: 10.1016/j.bpj.2010.12.1217] [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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36
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Villarroel A, Gomez-Posada JC, Aivar P, Alaimo A, Etxeberria A, Fernandez-Orth J, Areso P, Alberdi A. Calmodulin Independent Trafficking of Kv7.2 Channels. Biophys J 2011. [DOI: 10.1016/j.bpj.2010.12.2434] [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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37
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Roura-Ferrer M, Solé L, Oliveras A, Dahan R, Bielanska J, Villarroel A, Comes N, Felipe A. Impact of KCNE subunits on KCNQ1 (Kv7.1) channel membrane surface targeting. J Cell Physiol 2010; 225:692-700. [PMID: 20533308 DOI: 10.1002/jcp.22265] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The KCNQ1 (Kv7.1) channel plays an important role in cardiovascular physiology. Cardiomyocytes co-express KCNQ1 with KCNE1-5 proteins. KCNQ1 may co-associate with multiple KCNE regulatory subunits to generate different biophysically and pharmacologically distinct channels. Increasing evidence indicates that the location and targeting of channels are important determinants of their function. In this context, the presence of K(+) channels in sphingolipid-cholesterol-enriched membrane microdomains (lipid rafts) is under investigation. Lipid rafts are important for cardiovascular functioning. We aimed to determine whether KCNE subunits modify the localization and targeting of KCNQ1 channels in lipid rafts microdomains. HEK-293 cells were transiently transfected with KCNQ1 and KCNE1-5, and their traffic and presence in lipid rafts were analyzed. Only KCNQ1 and KCNE3, when expressed alone, co-localized in raft fractions. In addition, while KCNE2 and KCNE5 notably stained the cell surface, KCNQ1 and the rest of the KCNEs showed strong intracellular retention. KCNQ1 targets multiple membrane surface microdomains upon association with KCNE peptides. Thus, while KCNQ1/KCNE1 and KCNQ1/KCNE2 channels target lipid rafts, KCNQ1 associated with KCNE3-5 did not. Channel membrane dynamics, analyzed by fluorescence recovery after photobleaching (FRAP) experiments, further supported these results. In conclusion, the trafficking and targeting pattern of KCNQ1 can be influenced by its association with KCNEs. Since KCNQ1 is crucial for cardiovascular physiology, the temporal and spatial regulations that different KCNE subunits may confer to the channels could have a dramatic impact on membrane electrical activity and putative endocrine regulation.
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Affiliation(s)
- Meritxell Roura-Ferrer
- Molecular Physiology Laboratory, Departament de Bioquímica i Biologia Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Barcelona, Spain
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Alaimo A, Areso P, Villarroel A. Anomalous Calcium Dependent Binding of Calmodulin to KCNQ2 Potassium Channels. Biophys J 2010. [DOI: 10.1016/j.bpj.2009.12.3711] [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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39
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Roura-Ferrer M, Etxebarria A, Solé L, Oliveras A, Comes N, Villarroel A, Felipe A. Functional implications of KCNE subunit expression for the Kv7.5 (KCNQ5) channel. Cell Physiol Biochem 2009; 24:325-34. [PMID: 19910673 DOI: 10.1159/000257425] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/28/2009] [Indexed: 11/19/2022] Open
Abstract
Kv7 (KCNQ) proteins form a family of voltage-gated potassium channels that is comprised of five members, Kv7.1-Kv7.5. While Kv7.1 is crucial in the heart, the Kv7.2, Kv7.3, Kv7.4 and Kv7.5 channels contribute to the M-current in the nervous system. In addition to the brain, Kv7.5 is expressed in skeletal and smooth muscle, where its physiological role is currently under evaluation. Kv7 associations with KCNE accessory subunits (KCNE1-5) enhance channel diversity and their interaction provides mechanisms to respond to a variety of stimuli. KCNE peptides control the surface expression, voltage-dependence, kinetics of gating, unitary conductance, ion selectivity and pharmacology of several channels. KCNE subunits have been primarily studied in the heart; however, their activity in the brain and in many other tissues is being increasingly recognized. Here, we found that Kv7.5 and KCNE subunits are present in myoblasts. Therefore, oligomeric associations may underlie some Kv7.5 functional diversity in skeletal muscle. An extensive study in Xenopus oocytes and HEK-293 cells demonstrates that KCNE1 and KCNE3, but none of the other KCNE subunits, affect Kv7.5 currents. While KCNE1 slows activation and suppresses inward rectification, KCNE3 drastically inhibits Kv7.5 currents. In addition, KCNE1 increases Kv7.5 currents in HEK cells. Changes in gating and amplitude indicate functional interactions. Our results have physiological relevance since Kv7.5 is abundant in skeletal and smooth muscle and its association with KCNE peptides may fine-tune cellular responses.
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Alaimo A, Gómez-Posada JC, Aivar P, Etxeberría A, Rodriguez-Alfaro JA, Areso P, Villarroel A. Calmodulin activation limits the rate of KCNQ2 K+ channel exit from the endoplasmic reticulum. J Biol Chem 2009; 284:20668-75. [PMID: 19494108 DOI: 10.1074/jbc.m109.019539] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The potential regulation of protein trafficking by calmodulin (CaM) is a novel concept that remains to be substantiated. We proposed that KCNQ2 K+ channel trafficking is regulated by CaM binding to the C-terminal A and B helices. Here we show that the L339R mutation in helix A, which is linked to human benign neonatal convulsions, perturbs CaM binding to KCNQ2 channels and prevents their correct trafficking to the plasma membrane. We used glutathione S-transferase fused to helices A and B to examine the impact of this and other mutations in helix A (I340A, I340E, A343D, and R353G) on the interaction with CaM. The process appears to require at least two steps; the first involves the transient association of CaM with KCNQ2, and in the second, the complex adopts an "active" conformation that is more stable and is that which confers the capacity to exit the endoplasmic reticulum. Significantly, the mutations that we have analyzed mainly affect the stability of the active configuration of the complex, whereas Ca2+ alone appears to affect the initial binding step. The spectrum of responses from this collection of mutants revealed a strong correlation between adopting the active conformation and channel trafficking in mammalian cells. These data are entirely consistent with the concept that CaM bound to KCNQ2 acts as a Ca2+ sensor, conferring Ca2+ dependence to the trafficking of the channel to the plasma membrane and fully explaining the requirement of CaM binding for KCNQ2 function.
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Affiliation(s)
- Alessandro Alaimo
- Unidad de Biofísica, Consejo Superior de Investigaciones Cientificas-Universidad del Pais Vasco/Euskal Herriko Unibersitatea (CSIC-UPV/EHU), Spain
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Mencía A, González-Nieto D, Modamio-Høybjør S, Etxeberría A, Aránguez G, Salvador N, Del Castillo I, Villarroel A, Moreno F, Barrio L, Moreno-Pelayo MA. A novel KCNQ4 pore-region mutation (p.G296S) causes deafness by impairing cell-surface channel expression. Hum Genet 2007; 123:41-53. [PMID: 18030493 DOI: 10.1007/s00439-007-0447-7] [Citation(s) in RCA: 42] [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] [Subscribe] [Scholar Register] [Received: 06/30/2007] [Accepted: 11/09/2007] [Indexed: 01/08/2023]
Abstract
Mutations in the potassium channel gene KCNQ4 underlie DFNA2, a subtype of autosomal dominant progressive, high-frequency hearing loss. Based on a phenotype-guided mutational screening we have identified a novel mutation c.886G>A, leading to the p.G296S substitution in the pore region of KCNQ4 channel. The possible impact of this mutation on total KCNQ4 protein expression, relative surface expression and channel function was investigated. When the G296S mutant was expressed in Xenopus oocytes, electrophysiological recordings did not show voltage-activated K(+) currents. The p.G296S mutation impaired KCNQ4 channel activity in two manners. It greatly reduced surface expression and, secondarily, abolished channel function. The deficient expression at the cell surface membrane was further confirmed in non-permeabilized NIH-3T3 cells transfected with the mutant KCNQ4 tagged with the hemagglutinin epitope in the extracellular S1-S2 linker. Co-expression of mutant and wild type KCNQ4 in oocytes was performed to mimic the heterozygous condition of the p.G296S mutation in the patients. The results showed that the G296S mutant exerts a strong dominant-negative effect on potassium currents by reducing the wild type KCNQ4 channel expression at the cell surface. This is the first study to identify a trafficking-dependent dominant mechanism for the loss of KCNQ4 channel function in DFNA2.
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Affiliation(s)
- Angeles Mencía
- Unidad de Genética Molecular, Hospital Ramón y Cajal, Carretera de Colmenar Km 9, 28034, Madrid, Spain
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Etxeberria A, Aivar P, Rodriguez-Alfaro JA, Alaimo A, Villacé P, Gómez-Posada JC, Areso P, Villarroel A. Calmodulin regulates the trafficking of KCNQ2 potassium channels. FASEB J 2007; 22:1135-43. [PMID: 17993630 DOI: 10.1096/fj.07-9712com] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Voltage-dependent potassium KCNQ2 (Kv7.2) channels play a prominent role in the control of neuronal excitability. These channels must associate with calmodulin to function correctly and, indeed, a mutation (R353G) that impairs this association provokes the onset of a form of human neonatal epilepsy known as benign familial neonatal convulsions (BFNC). We show here that perturbation of calmodulin binding leads to endoplasmic reticulum (ER) retention of KCNQ2, reducing the number of channels that reach the plasma membrane. Interestingly, elevating the expression of calmodulin in the BFNC mutant partially restores the intracellular distribution of the KCNQ channel. In contrast, overexpression of a Ca(2+)-binding incompetent calmodulin or sequestering of calmodulin promotes the retention of wild-type channels in the ER. Thus, a direct interaction with Ca(2+)-calmodulin appears to be critical for the correct activity of KCNQ2 potassium channels as it controls the channels' exit from the ER.
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Affiliation(s)
- Ainhoa Etxeberria
- Unidad de Biofísica, CSIC-UPV/EHU, Universidad del País Vasco, Barrio Sarriena s/n, 48940 Leioa, Spain
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Abstract
The non-inactivating potassium M-current exerts a strong influence on neuronal excitability. The channels responsible for this current are made up of KCNQ subunits, and mutations in most of these produce human pathologies. Notably, in terms of excitation, mutations in either KCNQ2 or KCNQ3 lead to benign neonatal familial convulsions. Although a mere reduction of 25% in KCNQ2/3 function can increase excitability to epileptogenic levels, the potentiation of these subunits has anti-epileptogenic effects. After KCNQ2/3 heteromerization, current levels can augment as much as 10-fold, and we have discovered that there are three processes underlying this potentiation. First, there is an increase in the number of channels inserted in the membrane after heteromerization of the C-terminal region. Second, the N-terminal domain from KCNQ2 exerts a negative influence on the current level. Finally, Ala 315 of KCNQ3, a residue located in the inner vestibule after the selectivity filter, plays a critical role in preventing current flow in KCNQ3 homomeric channels, whereas it is permissive in heteromers in combination with Thr at the equivalent 276 position of KCNQ2.
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Affiliation(s)
- Ainhoa Etxeberria
- Instituto Cajal Consejo Superior de Investigaciones Científicas (CSIC), 28002 Madrid, Spain
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44
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Lane VM, Villarroel A, Wetzlich SE, Wetzlich S, Clifford A, Taylor I, Craigmill AL. Intravenous and subcutaneous pharmacokinetics of florfenicol in sheep. J Vet Pharmacol Ther 2004; 27:191-6. [PMID: 15305846 DOI: 10.1111/j.1365-2885.2004.00580.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [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: 11/28/2022]
Abstract
Pharmacokinetic parameters of florfenicol were determined in 10 adult sheep (five wethers and five ewes) after a single 40 mg/kg intravenous (i.v.) dose, and three daily subcutaneous (s.c.) doses of 40 mg/kg of a commercial preparation (Nuflor((R))). The concentration of florfenicol in serum samples was assayed using a proprietary HPLC assay method, and pharmacokinetic parameters derived for individual animal data by each route using compartmental and noncompartmental approaches. Two animals (one male and one female) were excluded due to observed i.v. dosing problems, and a biexponential model was found to fit the i.v. data well for six of the other eight animals. Data from two males showed prolonged low concentrations of florfenicol in serum and were better fit by a three-compartment model. The mean +/- SD for the half-lives of the distribution and elimination phases for the six sheep best fit with a two-compartment model were 0.069 +/- 0.018 and 1.01 +/- 0.09 h respectively, and for the V(d(ss)) and clearances were 0.503 +/- 0.035 L/kg and 366 +/- 53 mL/h/kg respectively. The data collected during the s.c. multiple dose study were analyzed using noncompartmental methods only. The bioavailability (F%) after s.c. dosing was calculated in three ways to compare estimation methods as steady-state had not been reached and single dose s.c. data were not obtained past 24 h. Using the AUC(0--24) and AUC(0--> infinity ) from the first dose, the F% values averaged 27 and 40% respectively. Using the AUC(0--> infinity ) for all doses, the F% was 65%. Calculations of the mean time during which the serum concentration exceeded 0.5 and 1.0 microg/mL were 105 +/- 3.9 and 74.7 +/- 12.2 h respectively.
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Affiliation(s)
- V M Lane
- Population Health and Reproduction, School of Veterinary Medicine, University of California, Davis, CA, USA
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45
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Neco P, Giner D, Viniegra S, Borges R, Villarroel A, Gutiérrez LM. New roles of myosin II during vesicle transport and fusion in chromaffin cells. J Biol Chem 2004; 279:27450-7. [PMID: 15069078 DOI: 10.1074/jbc.m311462200] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.4] [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: 11/06/2022] Open
Abstract
Modified herpes virus (amplicons) were used to express myosin regulatory light chain (RLC) chimeras with green fluorescent protein (GFP) in cultured bovine chromaffin cells to study myosin II implication in secretion. After infection, RLC-GFP constructs were clearly identified in the cytoplasm and accumulated in the cortical region, forming a complex network that co-localized with cortical F-actin. Cells expressing wild type RLC-GFP maintained normal vesicle mobility, whereas cells expressing an unphosphorylatable form (T18A/S19A RLC-GFP) presented severe restrictions in granule movement as measured by individual tracking in dynamic confocal microscopy studies. Interestingly, the overexpression of this mutant form of RLC also affected the initial secretory burst elicited by either high K(+) or BaCl(2), as well as the secretion induced by fast release of calcium from caged compounds in individual cells. Moreover, T18A/S19A RLC-GFP-infected cells presented slower fusion kinetics of individual granules compared with controls as measured by analysis of amperometric spikes. Taken together, our results demonstrate the implication of myosin II in the transport of vesicles, and, surprisingly, in the final phases of exocytosis involving transitions affecting the activity of docked granules, and therefore uncovering a new role for this cytoskeletal element.
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Affiliation(s)
- Patricia Neco
- Instituto de Neurociencias, Centro Mixto CSIC-Universidad Miguel Hernandez, E-03550 Alicante, Spain
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46
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Yus-Nájera E, Muñoz A, Salvador N, Jensen BS, Rasmussen HB, Defelipe J, Villarroel A. Localization of KCNQ5 in the normal and epileptic human temporal neocortex and hippocampal formation. Neuroscience 2003; 120:353-64. [PMID: 12890507 DOI: 10.1016/s0306-4522(03)00321-x] [Citation(s) in RCA: 52] [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] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The KCNQ family of voltage-dependent non-inactivating K+ channels is composed of five members, four of which (KCNQ2-5) are expressed in the CNS and are responsible for the M-current. Mutations in either KCNQ2 or KCNQ3 lead to a hereditary form of dominant generalized epilepsy. Using specific antisera to the KCNQ2, KCNQ3 and KCNQ5 subunits, we found that KCNQ3 co-immunoprecipitated with KCNQ2 and KCNQ5 subunits, but no association was detected between KCNQ2 and KCNQ5. Intense KCNQ5 immunoreactivity was found to be widely distributed throughout the temporal neocortex and the hippocampal formation. In these structures, both pyramidal and non-pyramidal neurons and a population of glial cells in the white matter expressed the KCNQ5 subunit. In the sclerotic areas of the CA fields of epileptic patients, a marked loss of KCNQ5 immunoreactive pyramidal neurons was found in relation with the loss of neurons in these regions. However, in the regions adjacent to the sclerotic areas, the distribution and intensity of KCNQ5 immunostaining was apparently normal. The widespread distribution of KCNQ5 subunits, its persistence in pharmacoresistant epilepsy, along with the significant role of the M-current in the control of neuronal excitability, makes this protein a possible target for the development of anticonvulsant drugs.
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Affiliation(s)
- E Yus-Nájera
- Instituto Cajal, CSIC, Avenida Dr. Arce 37, 28002 Madrid, Spain
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47
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Yus-Najera E, Santana-Castro I, Villarroel A. The identification and characterization of a noncontinuous calmodulin-binding site in noninactivating voltage-dependent KCNQ potassium channels. J Biol Chem 2002; 277:28545-53. [PMID: 12032157 DOI: 10.1074/jbc.m204130200] [Citation(s) in RCA: 157] [Impact Index Per Article: 7.1] [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: 11/06/2022] Open
Abstract
We show here that in a yeast two-hybrid assay calmodulin (CaM) interacts with the intracellular C-terminal region of several members of the KCNQ family of potassium channels. CaM co-immunoprecipitates with KCNQ2, KCNQ3, or KCNQ5 subunits better in the absence than in the presence of Ca2+. Moreover, in two-hybrid assays where it is possible to detect interactions with apo-CaM but not with Ca2+-bound calmodulin, we localized the CaM-binding site to a region that is predicted to contain two alpha-helices (A and B). These two helices encompass approximately 85 amino acids, and in KCNQ2 they are separated by a dispensable stretch of approximately 130 amino acids. Within this CaM-binding domain, we found an IQ-like CaM-binding motif in helix A and two overlapping consensus 1-5-10 CaM-binding motifs in helix B. Point mutations in helix A or B were capable of abolishing CaM binding in the two-hybrid assay. Moreover, glutathione S-transferase fusion proteins containing helices A and B were capable of binding to CaM, indicating that the interaction with KCNQ channels is direct. Full-length CaM (both N and C lobes) and a functional EF-1 hand were required for these interactions to occur. These observations suggest that apo-CaM is bound to neuronal KCNQ channels at low resting Ca2+ levels and that this interaction is disturbed when the [Ca2+] is raised. Thus, we propose that CaM acts as a mediator in the Ca2+-dependent modulation of KCNQ channels.
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Affiliation(s)
- Eva Yus-Najera
- Instituto Cajal, Consejo Superior de Investigaciones, Avenida, Dr. Arce 37, 28002 Madrid, Spain
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48
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Abstract
Opening of the NMDA receptor channel requires simultaneous binding of glutamate and glycine. Although the binding sites for each agonist are in different subunits, the presence of one agonist influences the binding of the other. We have localized regions in the S1 binding domain of both subunits required for the transmission of allosteric signals from the glutamate binding NR2A subunit to the glycine binding NR1 subunit. Three-dimensional modeling indicates that these segments are not directly involved in ligand binding, but likely form solvent-accessible loops protruding out of the binding pocket, making them suitable to relay interactions between adjacent subunits. Thus, these segments mediate negative allosteric coupling between the two subunit types that form the NMDA receptor.
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Affiliation(s)
- M P Regalado
- Instituto Cajal, Consejo Superior de Investigaciones Científicas, 28002, Madrid, Spain
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49
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Abstract
Single-channel recording from visualised endplates in freshly dissociated muscles from postnatal and denervated rat muscle revealed the presence of a low conductance, fetal type of acetylcholine receptor. Kinetic analysis showed a main component in the burst durations with a mean of 10.8 +/- 2.7 ms (n = 29). Receptors from female rats had an additional 27.3 +/- 5.5 ms (n = 5) kinetic component which was found in one-third of the 15 female endplates. Recordings from male and female denervated muscles gave more homogeneous kinetics with single time constants of 7.2 +/- 1.3 and 7.4 +/- 1.3 ms, respectively. It is concluded that the acetylcholine receptor channels present during early development are different from those of denervated muscle.
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Affiliation(s)
- A Villarroel
- Department of Physiology and Biophysics, Dalhousie University School of Medicine, 3R1 Tupper Medical Building, Halifax, Nova Scotia, Canada B3H 4H7.
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50
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Fayyazuddin A, Villarroel A, Le Goff A, Lerma J, Neyton J. Four residues of the extracellular N-terminal domain of the NR2A subunit control high-affinity Zn2+ binding to NMDA receptors. Neuron 2000; 25:683-94. [PMID: 10774735 DOI: 10.1016/s0896-6273(00)81070-3] [Citation(s) in RCA: 137] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
NMDA receptors are allosterically inhibited by Zn2+ ions in a voltage-independent manner. The apparent affinity for Zn2+ of the heteromeric NMDA receptors is determined by the subtype of NR2 subunit expressed, with NR2A-containing receptors being the most sensitive (IC50, approximately 20 nM) and NR2C-containing receptors being the least sensitive (IC50, approximately 30 microM). Using chimeras constructed from these two NR2 subtypes, we show that the N-terminal LIVBP-like domain of the NR2A subunit controls the high-affinity Zn2+ inhibition. Mutations at four residues in this domain markedly reduce Zn2+ affinity (by up to >500-fold) without affecting either receptor activation by glutamate and glycine or inhibition by extracellular protons and Ni2+ ions, indicating that these residues most likely participate in high-affinity Zn2+ binding.
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Affiliation(s)
- A Fayyazuddin
- Laboratoire de Neurobiologie, Ecole Normale Supérieure, Centre National de la Recherche Scientificque/Unité Mixte de Recherche 8544, Paris, France
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