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Chen D, Su J, Huang X, Chen H, Jiang T, Zhi C, Zhou Z, Zhang B, Yu L, Jiang X. Establishment and characterization of ZJUCHi003: an induced pluripotent stem cell line from a patient with Temple-Baraitser/Zimmermann-Laband syndrome carrying KCNH1 c.1070G > A (p.R357Q) variant. Hum Cell 2024; 37:832-839. [PMID: 38372889 DOI: 10.1007/s13577-024-01031-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Accepted: 01/18/2024] [Indexed: 02/20/2024]
Abstract
Pathogenic variants of the KCNH1 gene can cause dominant-inherited Temple-Baraitser/Zimmermann-Laband syndrome with severe mental retardation, seizure, gingival hyperplasia and nail hypoplasia. This study established an induced pluripotent stem cell (iPSC) line using urinary cells from a girl with KCNH1 recurrent/hotspot pathogenic variant c.1070G > A (p.R357Q). The cell identity, pluripotency, karyotypic integrity, absence of reprogramming virus and mycoplasma contamination, and differential potential to three germ layers of the iPSC line, named as ZJUCHi003, were characterized and confirmed. Furthermore, ZJUCHi003-derived neurons manifested slower action potential repolarization process and wider action potential half-width than the normal neurons. This cell line will be useful for investigating the pathogenic mechanisms of KCNH1 variants-associated symptoms, as well as for evaluating novel therapeutic approaches.
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Affiliation(s)
- Die Chen
- Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, 310052, China
- Key Laboratory of Genetic and Developmental Disorders of Zhejiang Province, Hangzhou, China
| | - Jimei Su
- Department of Stomatology, Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, 310052, China
| | - Xueying Huang
- Shanghai Key Laboratory of Maternal Fetal Medicine, Clinical and Translational Research Center, Shanghai First Maternity and Infant Hospital, School of Medicine, Shanghai Institute of Maternal-Fetal Medicine and Gynecologic Oncology, Tongji University, Shanghai, 201204, China
| | - Hongyu Chen
- Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, 310052, China
| | - Tiejia Jiang
- Department of Neurology, Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, 310052, China
| | - Chunchun Zhi
- Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, 310052, China
- Key Laboratory of Genetic and Developmental Disorders of Zhejiang Province, Hangzhou, China
| | - Zuolin Zhou
- Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, 310052, China
- Key Laboratory of Genetic and Developmental Disorders of Zhejiang Province, Hangzhou, China
| | - Bing Zhang
- Shanghai Key Laboratory of Maternal Fetal Medicine, Clinical and Translational Research Center, Shanghai First Maternity and Infant Hospital, School of Medicine, Shanghai Institute of Maternal-Fetal Medicine and Gynecologic Oncology, Tongji University, Shanghai, 201204, China
| | - Lan Yu
- Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, 310052, China.
| | - Xiaoling Jiang
- Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, 310052, China.
- Key Laboratory of Genetic and Developmental Disorders of Zhejiang Province, Hangzhou, China.
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Wang ZJ, Ghorbani M, Chen X, Tiwari PB, Klauda JB, Brelidze TI. Molecular mechanism of EAG1 channel inhibition by imipramine binding to the PAS domain. J Biol Chem 2023; 299:105391. [PMID: 37898402 PMCID: PMC10687071 DOI: 10.1016/j.jbc.2023.105391] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Revised: 10/17/2023] [Accepted: 10/19/2023] [Indexed: 10/30/2023] Open
Abstract
Ether-a-go-go (EAG) channels are key regulators of neuronal excitability and tumorigenesis. EAG channels contain an N-terminal Per-Arnt-Sim (PAS) domain that can regulate currents from EAG channels by binding small molecules. The molecular mechanism of this regulation is not clear. Using surface plasmon resonance and electrophysiology we show that a small molecule ligand imipramine can bind to the PAS domain of EAG1 channels and inhibit EAG1 currents via this binding. We further used a combination of molecular dynamics (MD) simulations, electrophysiology, and mutagenesis to investigate the molecular mechanism of EAG1 current inhibition by imipramine binding to the PAS domain. We found that Tyr71, located at the entrance to the PAS domain cavity, serves as a "gatekeeper" limiting access of imipramine to the cavity. MD simulations indicate that the hydrophobic electrostatic profile of the cavity facilitates imipramine binding and in silico mutations of hydrophobic cavity-lining residues to negatively charged glutamates decreased imipramine binding. Probing the PAS domain cavity-lining residues with site-directed mutagenesis, guided by MD simulations, identified D39 and R84 as residues essential for the EAG1 channel inhibition by imipramine binding to the PAS domain. Taken together, our study identified specific residues in the PAS domain that could increase or decrease EAG1 current inhibition by imipramine binding to the PAS domain. These findings should further the understanding of molecular mechanisms of EAG1 channel regulation by ligands and facilitate the development of therapeutic agents targeting these channels.
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Affiliation(s)
- Ze-Jun Wang
- Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, District of Columbia, USA
| | - Mahdi Ghorbani
- Department of Chemical and Biomolecular Engineering, University of Maryland, College Park, Maryland, USA
| | - Xi Chen
- Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, District of Columbia, USA
| | - Purushottam B Tiwari
- Department of Oncology, Georgetown University Medical Center, Washington, District of Columbia, USA
| | - Jeffery B Klauda
- Department of Chemical and Biomolecular Engineering, University of Maryland, College Park, Maryland, USA; Institute for Physical Science and Technology and Biophysics Graduate Program, University of Maryland, College Park, Maryland, USA.
| | - Tinatin I Brelidze
- Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, District of Columbia, USA.
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Hsieh CH, Chou CC, Fang YC, Hsu PH, Chiu YH, Yang CS, Jow GM, Tang CY, Jeng CJ. 14-3-3 proteins regulate cullin 7-mediated Eag1 degradation. Cell Biosci 2023; 13:18. [PMID: 36717938 PMCID: PMC9885684 DOI: 10.1186/s13578-023-00969-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Accepted: 01/23/2023] [Indexed: 01/31/2023] Open
Abstract
BACKGROUND Mutations in the human gene encoding the neuron-specific Eag1 (KV10.1; KCNH1) potassium channel are linked to congenital neurodevelopmental diseases. Disease-causing mutant Eag1 channels manifest aberrant gating function and defective protein homeostasis. Both the E3 ubiquitin ligase cullin 7 (Cul7) and the small acid protein 14-3-3 serve as binding partners of Eag1. Cul7 mediates proteasomal and lysosomal degradation of Eag1 protein, whereas over-expression of 14-3-3 notably reduces Eag1 channel activity. It remains unclear whether 14-3-3 may also contribute to Eag1 protein homeostasis. RESULTS In human cell line and native rat neurons, disruptions of endogenous 14-3-3 function with the peptide inhibitor difopein or specific RNA interference up-regulated Eag1 protein level in a transcription-independent manner. Difopein hindered Eag1 protein ubiquitination at the endoplasmic reticulum and the plasma membrane, effectively promoting the stability of both immature and mature Eag1 proteins. Suppression of endogenous 14-3-3 function also reduced excitotoxicity-associated Eag1 degradation in neurons. Difopein diminished Cul7-mediated Eag1 degradation, and Cul7 knock-down abolished the effect of difopein on Eag1. Inhibition of endogenous 14-3-3 function substantially perturbed the interaction of Eag1 with Cul7. Further structural analyses suggested that the intracellular Per-Arnt-Sim (PAS) domain and cyclic nucleotide-binding homology domain (CNBHD) of Eag1 are essential for the regulatory effect of 14-3-3 proteins. Significantly, suppression of endogenous 14-3-3 function reduced Cul7-mediated degradation of disease-associated Eag1 mutant proteins. CONCLUSION Overall these results highlight a chaperone-like role of endogenous 14-3-3 proteins in regulating Eag1 protein homeostasis, as well as a therapeutic potential of 14-3-3 modulators in correcting defective protein expression of disease-causing Eag1 mutants.
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Affiliation(s)
- Chang-Heng Hsieh
- grid.260539.b0000 0001 2059 7017Institute of Anatomy and Cell Biology, College of Medicine, National Yang Ming Chiao Tung University, Taipei, 112 Taiwan
| | - Chia-Cheng Chou
- grid.36020.370000 0000 8889 3720National Laboratory Animal Center, National Applied Research Laboratories, Taipei, Taiwan
| | - Ya-Ching Fang
- grid.260539.b0000 0001 2059 7017Institute of Anatomy and Cell Biology, College of Medicine, National Yang Ming Chiao Tung University, Taipei, 112 Taiwan ,grid.19188.390000 0004 0546 0241Department of Physiology, College of Medicine, National Taiwan University, Taipei, 100 Taiwan
| | - Po-Hao Hsu
- grid.260539.b0000 0001 2059 7017Institute of Anatomy and Cell Biology, College of Medicine, National Yang Ming Chiao Tung University, Taipei, 112 Taiwan ,grid.19188.390000 0004 0546 0241Department of Physiology, College of Medicine, National Taiwan University, Taipei, 100 Taiwan
| | - Yi-Hung Chiu
- grid.260539.b0000 0001 2059 7017Institute of Anatomy and Cell Biology, College of Medicine, National Yang Ming Chiao Tung University, Taipei, 112 Taiwan
| | - Chi-Sheng Yang
- grid.260539.b0000 0001 2059 7017Institute of Anatomy and Cell Biology, College of Medicine, National Yang Ming Chiao Tung University, Taipei, 112 Taiwan
| | - Guey-Mei Jow
- grid.256105.50000 0004 1937 1063School of Medicine, Fu-Jen Catholic University, New Taipei City, Taiwan
| | - Chih-Yung Tang
- grid.19188.390000 0004 0546 0241Department of Physiology, College of Medicine, National Taiwan University, Taipei, 100 Taiwan
| | - Chung-Jiuan Jeng
- grid.260539.b0000 0001 2059 7017Institute of Anatomy and Cell Biology, College of Medicine, National Yang Ming Chiao Tung University, Taipei, 112 Taiwan ,grid.260539.b0000 0001 2059 7017Brain Research Center, National Yang Ming Chiao Tung University, Taipei, Taiwan
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Luis E, Anaya-Hernández A, León-Sánchez P, Durán-Pastén ML. The Kv10.1 Channel: A Promising Target in Cancer. Int J Mol Sci 2022; 23:ijms23158458. [PMID: 35955591 PMCID: PMC9369319 DOI: 10.3390/ijms23158458] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Revised: 07/25/2022] [Accepted: 07/27/2022] [Indexed: 12/19/2022] Open
Abstract
Carcinogenesis is a multistage process involving the dysregulation of multiple genes, proteins, and pathways that make any normal cell acquire a cancer cell phenotype. Therefore, it is no surprise that numerous ion channels could be involved in this process. Since their discovery and subsequent cloning, ion channels have been established as therapeutic targets in excitable cell pathologies (e.g., cardiac arrhythmias or epilepsy); however, their involvement in non-excitable cell pathologies is relatively recent. Among all ion channels, the voltage-gated potassium channels Kv10.1 have been established as a promising target in cancer treatment due to their high expression in tumoral tissues compared to low levels in healthy tissues.
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Affiliation(s)
- Enoch Luis
- Cátedras CONACYT—Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Circuito Exterior s/n, C.U., Ciudad de México 04510, Mexico
- Laboratorio Nacional de Canalopatías, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Circuito Exterior s/n, C.U., Ciudad de México 04510, Mexico; (P.L.-S.); (M.L.D.-P.)
- Correspondence:
| | - Arely Anaya-Hernández
- Centro de Investigación en Genética y Ambiente, Universidad Autónoma de Tlaxcala, Km. 10.5 Autopista Tlaxcala-San Martín, Tlaxcala 90120, Mexico;
| | - Paulina León-Sánchez
- Laboratorio Nacional de Canalopatías, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Circuito Exterior s/n, C.U., Ciudad de México 04510, Mexico; (P.L.-S.); (M.L.D.-P.)
| | - María Luisa Durán-Pastén
- Laboratorio Nacional de Canalopatías, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Circuito Exterior s/n, C.U., Ciudad de México 04510, Mexico; (P.L.-S.); (M.L.D.-P.)
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5
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Loza-Huerta A, Milo E, Picones A, Hernández-Cruz A, Luis E. Thallium-sensitive fluorescent assay reveals loperamide as a new inhibitor of the potassium channel Kv10.1. Pharmacol Rep 2021; 73:1744-1753. [PMID: 34213738 DOI: 10.1007/s43440-021-00304-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Revised: 06/21/2021] [Accepted: 06/23/2021] [Indexed: 11/28/2022]
Abstract
BACKGROUND Ion channels have been proposed as therapeutic targets for different types of malignancies. One of the most studied ion channels in cancer is the voltage-gated potassium channel ether-à-go-go 1 or Kv10.1. Various studies have shown that Kv10.1 expression induces the proliferation of several cancer cell lines and in vivo tumor models, while blocking or silencing inhibits proliferation. Kv10.1 is a promising target for drug discovery modulators that could be used in cancer treatment. This work aimed to screen for new Kv10.1 channel modulators using a thallium influx-based assay. METHODS Pharmacological effects of small molecules on Kv10.1 channel activity were studied using a thallium-based fluorescent assay and patch-clamp electrophysiological recordings, both performed in HEK293 stably expressing the human Kv10.1 potassium channel. RESULTS In thallium-sensitive fluorescent assays, we found that the small molecules loperamide and amitriptyline exert a potent inhibition on the activity of the oncogenic potassium channel Kv10.1. These results were confirmed by electrophysiological recordings, which showed that loperamide and amitriptyline decreased the amplitude of Kv10.1 currents in a dose-dependent manner. Both drugs could be promising tools for further studies. CONCLUSIONS Thallium-sensitive fluorescent assay represents a reliable methodological tool for the primary screening of different molecules with potential activity on Kv10.1 channels or other K+ channels.
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Affiliation(s)
- Arlet Loza-Huerta
- Laboratorio Nacional de Canalopatías, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Circuito Exterior s/n, C.U. 04510, Mexico City, Mexico
| | - Edgar Milo
- Laboratorio Nacional de Canalopatías, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Circuito Exterior s/n, C.U. 04510, Mexico City, Mexico
| | - Arturo Picones
- Laboratorio Nacional de Canalopatías, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Circuito Exterior s/n, C.U. 04510, Mexico City, Mexico
| | - Arturo Hernández-Cruz
- Laboratorio Nacional de Canalopatías, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Circuito Exterior s/n, C.U. 04510, Mexico City, Mexico.,Departamento de Neurociencia Cognitiva, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Circuito Exterior s/n, C.U. 04510, Mexico City, Mexico
| | - Enoch Luis
- Laboratorio Nacional de Canalopatías, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Circuito Exterior s/n, C.U. 04510, Mexico City, Mexico. .,Cátedras CONACYT - Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Circuito Exterior s/n, C.U. 04510, Mexico City, Mexico.
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6
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Toplak Ž, Hendrickx LA, Abdelaziz R, Shi X, Peigneur S, Tomašič T, Tytgat J, Peterlin-Mašič L, Pardo LA. Overcoming challenges of HERG potassium channel liability through rational design: Eag1 inhibitors for cancer treatment. Med Res Rev 2021; 42:183-226. [PMID: 33945158 DOI: 10.1002/med.21808] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Revised: 02/18/2021] [Accepted: 03/31/2021] [Indexed: 12/11/2022]
Abstract
Two decades of research have proven the relevance of ion channel expression for tumor progression in virtually every indication, and it has become clear that inhibition of specific ion channels will eventually become part of the oncology therapeutic arsenal. However, ion channels play relevant roles in all aspects of physiology, and specificity for the tumor tissue remains a challenge to avoid undesired effects. Eag1 (KV 10.1) is a voltage-gated potassium channel whose expression is very restricted in healthy tissues outside of the brain, while it is overexpressed in 70% of human tumors. Inhibition of Eag1 reduces tumor growth, but the search for potent inhibitors for tumor therapy suffers from the structural similarities with the cardiac HERG channel, a major off-target. Existing inhibitors show low specificity between the two channels, and screenings for Eag1 binders are prone to enrichment in compounds that also bind HERG. Rational drug design requires knowledge of the structure of the target and the understanding of structure-function relationships. Recent studies have shown subtle structural differences between Eag1 and HERG channels with profound functional impact. Thus, although both targets' structure is likely too similar to identify leads that exclusively bind to one of the channels, the structural information combined with the new knowledge of the functional relevance of particular residues or areas suggests the possibility of selective targeting of Eag1 in cancer therapies. Further development of selective Eag1 inhibitors can lead to first-in-class compounds for the treatment of different cancers.
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Affiliation(s)
- Žan Toplak
- Faculty of Pharmacy, University of Ljubljana, Ljubljana, Slovenia
| | - Louise A Hendrickx
- Department of Toxicology and Pharmacology, University of Leuven, Leuven, Belgium
| | - Reham Abdelaziz
- AG Oncophysiology, Max-Planck Institute for Experimental Medicine, Göttingen, Germany
| | - Xiaoyi Shi
- AG Oncophysiology, Max-Planck Institute for Experimental Medicine, Göttingen, Germany
| | - Steve Peigneur
- Department of Toxicology and Pharmacology, University of Leuven, Leuven, Belgium
| | - Tihomir Tomašič
- Faculty of Pharmacy, University of Ljubljana, Ljubljana, Slovenia
| | - Jan Tytgat
- Department of Toxicology and Pharmacology, University of Leuven, Leuven, Belgium
| | | | - Luis A Pardo
- AG Oncophysiology, Max-Planck Institute for Experimental Medicine, Göttingen, Germany
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Fang YC, Fu SJ, Hsu PH, Chang PT, Huang JJ, Chiu YC, Liao YF, Jow GM, Tang CY, Jeng CJ. Identification of MKRN1 as a second E3 ligase for Eag1 potassium channels reveals regulation via differential degradation. J Biol Chem 2021; 296:100484. [PMID: 33647316 PMCID: PMC8039722 DOI: 10.1016/j.jbc.2021.100484] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Revised: 02/17/2021] [Accepted: 02/25/2021] [Indexed: 11/02/2022] Open
Abstract
Mutations in the human gene encoding the neuron-specific Eag1 voltage-gated K+ channel are associated with neurodevelopmental diseases, indicating an important role of Eag1 during brain development. A disease-causing Eag1 mutation is linked to decreased protein stability that involves enhanced protein degradation by the E3 ubiquitin ligase cullin 7 (CUL7). The general mechanisms governing protein homeostasis of plasma membrane- and endoplasmic reticulum (ER)-localized Eag1 K+ channels, however, remain unclear. By using yeast two-hybrid screening, we identified another E3 ubiquitin ligase, makorin ring finger protein 1 (MKRN1), as a novel binding partner primarily interacting with the carboxyl-terminal region of Eag1. MKRN1 mainly interacts with ER-localized immature core-glycosylated, as well as nascent nonglycosylated, Eag1 proteins. MKRN1 promotes polyubiquitination and ER-associated proteasomal degradation of immature Eag1 proteins. Although both CUL7 and MKRN1 contribute to ER quality control of immature core-glycosylated Eag1 proteins, MKRN1, but not CUL7, associates with and promotes degradation of nascent, nonglycosylated Eag1 proteins at the ER. In direct contrast to the role of CUL7 in regulating both ER and peripheral quality controls of Eag1, MKRN1 is exclusively responsible for the early stage of Eag1 maturation at the ER. We further demonstrated that both CUL7 and MKRN1 contribute to protein quality control of additional disease-causing Eag1 mutants associated with defective protein homeostasis. Our data suggest that the presence of this dual ubiquitination system differentially maintains Eag1 protein homeostasis and may ensure efficient removal of disease-associated misfolded Eag1 mutant channels.
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Affiliation(s)
- Ya-Ching Fang
- Institute of Anatomy and Cell Biology, School of Medicine, National Yang-Ming University, Taipei, Taiwan; Department of Physiology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Ssu-Ju Fu
- Department of Physiology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Po-Hao Hsu
- Institute of Anatomy and Cell Biology, School of Medicine, National Yang-Ming University, Taipei, Taiwan; Department of Physiology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Pei-Tzu Chang
- Institute of Anatomy and Cell Biology, School of Medicine, National Yang-Ming University, Taipei, Taiwan
| | - Jing-Jia Huang
- Department of Physiology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Yi-Chih Chiu
- Institute of Anatomy and Cell Biology, School of Medicine, National Yang-Ming University, Taipei, Taiwan
| | - Yi-Fan Liao
- Institute of Anatomy and Cell Biology, School of Medicine, National Yang-Ming University, Taipei, Taiwan
| | - Guey-Mei Jow
- School of Medicine, Fu-Jen Catholic University, New Taipei City, Taiwan
| | - Chih-Yung Tang
- Department of Physiology, College of Medicine, National Taiwan University, Taipei, Taiwan.
| | - Chung-Jiuan Jeng
- Institute of Anatomy and Cell Biology, School of Medicine, National Yang-Ming University, Taipei, Taiwan; Brain Research Center, National Yang-Ming University, Taipei, Taiwan.
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8
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The functional analysis of Cullin 7 E3 ubiquitin ligases in cancer. Oncogenesis 2020; 9:98. [PMID: 33130829 PMCID: PMC7603503 DOI: 10.1038/s41389-020-00276-w] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2020] [Revised: 09/11/2020] [Accepted: 09/21/2020] [Indexed: 01/09/2023] Open
Abstract
Cullin (CUL) proteins have critical roles in development and cancer, however few studies on CUL7 have been reported due to its characteristic molecular structure. CUL7 forms a complex with the ROC1 ring finger protein, and only two F-box proteins Fbxw8 and Fbxw11 have been shown to bind to CUL7. Interestingly, CUL7 can interact with its substrates by forming a novel complex that is independent of these two F-box proteins. The biological implications of CUL-ring ligase 7 (CRL7) suggest that the CRL7 may not only perform a proteolytic function but may also play a non-proteolytic role. Among the existing studied CRL7-based E3 ligases, CUL7 exerts both tumor promotion and suppression in a context-dependent manner. Currently, the mechanism of CUL7 in cancer remains unclear, and no studies have addressed potential therapies targeting CUL7. Consistent with the roles of the various CRL7 adaptors exhibit, targeting CRL7 might be an effective strategy for cancer prevention and treatment. We systematically describe the recent major advances in understanding the role of the CUL7 E3 ligase in cancer and further summarize its potential use in clinical therapy.
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9
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Movsisyan N, Pardo LA. Kv10.1 Regulates Microtubule Dynamics during Mitosis. Cancers (Basel) 2020; 12:cancers12092409. [PMID: 32854244 PMCID: PMC7564071 DOI: 10.3390/cancers12092409] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Revised: 08/13/2020] [Accepted: 08/18/2020] [Indexed: 12/16/2022] Open
Abstract
Kv10.1 (potassium voltage-gated channel subfamily H member 1, known as EAG1 or Ether-à-go-go 1), is a voltage-gated potassium channel, prevailingly expressed in the central nervous system. The aberrant expression of Kv10.1 is detected in over 70% of all human tumor tissues and correlates with poorer prognosis. In peripheral tissues, Kv10.1 is expressed almost exclusively during the G2/M phase of the cell cycle and regulates its progression-downregulation of Kv10.1 extends the duration of the G2/M phase both in cancer and healthy cells. Here, using biochemical and imaging techniques, such as live-cell measurements of microtubule growth and of cytosolic calcium, we elucidate the mechanisms of Kv10.1-mediated regulation at the G2/M phase. We show that Kv10.1 has a dual effect on mitotic microtubule dynamics. Through the functional interaction with ORAI1 (calcium release-activated calcium channel protein 1), it modulates cytosolic calcium oscillations, thereby changing microtubule behavior. The inhibition of either Kv10.1 or ORAI1 stabilizes the microtubules. In contrast, the knockdown of Kv10.1 increases the dynamicity of mitotic microtubules, resulting in a stronger spindle assembly checkpoint, greater mitotic spindle angle, and a decrease in lagging chromosomes. Understanding of Kv10.1-mediated modulation of the microtubule architecture will help to comprehend how cancer tissue benefits from the presence of Kv10.1, and thereby increase the efficacy and safety of Kv10.1-directed therapeutic strategies.
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Berg DJ, Kartheiser K, Leyrer M, Saali A, Berson DM. Transcriptomic Signatures of Postnatal and Adult Intrinsically Photosensitive Ganglion Cells. eNeuro 2019; 6:ENEURO.0022-19.2019. [PMID: 31387875 PMCID: PMC6712207 DOI: 10.1523/eneuro.0022-19.2019] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Revised: 07/19/2019] [Accepted: 07/23/2019] [Indexed: 11/21/2022] Open
Abstract
Intrinsically photosensitive retinal ganglion cells (ipRGCs) are rare mammalian photoreceptors essential for non-image-forming vision functions, such as circadian photoentrainment and the pupillary light reflex. They comprise multiple subtypes distinguishable by morphology, physiology, projections, and levels of expression of melanopsin (Opn4), their photopigment. The molecular programs that distinguish ipRGCs from other ganglion cells and ipRGC subtypes from one another remain elusive. Here, we present comprehensive gene expression profiles of early postnatal and adult mouse ipRGCs purified from two lines of reporter mice that mark different sets of ipRGC subtypes. We find dozens of novel genes highly enriched in ipRGCs. We reveal that Rasgrp1 and Tbx20 are selectively expressed in subsets of ipRGCs, though these molecularly defined groups imperfectly match established ipRGC subtypes. We demonstrate that the ipRGCs regulating circadian photoentrainment are diverse at the molecular level. Our findings reveal unexpected complexity in gene expression patterns across mammalian ipRGC subtypes.
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Affiliation(s)
- Daniel J Berg
- Molecular Biology, Cellular Biology, and Biochemistry Program, Brown University, Providence, Rhode Island 02912
- Department of Neuroscience, Brown University, Providence, Rhode Island 02912
| | | | - Megan Leyrer
- Department of Neuroscience, Brown University, Providence, Rhode Island 02912
| | - Alexandra Saali
- Department of Neuroscience, Brown University, Providence, Rhode Island 02912
| | - David M Berson
- Department of Neuroscience, Brown University, Providence, Rhode Island 02912
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Ma L, Chin YKY, Dekan Z, Herzig V, Chow CY, Heighway J, Lam SW, Guillemin GJ, Alewood PF, King GF. Novel venom-derived inhibitors of the human EAG channel, a putative antiepileptic drug target. Biochem Pharmacol 2018; 158:60-72. [PMID: 30149017 DOI: 10.1016/j.bcp.2018.08.038] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Accepted: 08/22/2018] [Indexed: 12/17/2022]
Abstract
Recently, we and other groups revealed that gain-of-function mutations in the human ether à go-go voltage-gated potassium channel hEAG1 (Kv10.1) lead to developmental disorders with associated infantile-onset epilepsy. However, the physiological role of hEAG1 in the central nervous system remains elusive. Potent and selective antagonists of hEAG1 are therefore much sought after, both as pharmacological tools for studying the (patho)physiological functions of this enigmatic channel and as potential leads for development of anti-epileptic drugs. Since animal venoms are a rich source of potent ion channel modifiers that have been finely tuned by millions of year of evolution, we screened 108 arachnid venoms for hEAG1 inhibitors using electrophysiology. Two hit peptides (Aa1a and Ap1a) were isolated, sequenced, and chemically synthesised for structure-function studies. Both of these hEAG1 inhibitors are C-terminally amidated peptides containing an inhibitor cystine knot motif, which provides them with exceptional stability in both plasma and cerebrospinal fluid. Aa1a and Ap1a are the most potent peptidic inhibitors of hEAG1 reported to date, and they present a novel mode of action by targeting both the activation and inactivation gating of the channel. These peptides should be useful pharmacological tools for probing hEAG1 function as well as informative leads for the development of novel anti-epileptic drugs.
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Affiliation(s)
- Linlin Ma
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia.
| | - Yanni K Y Chin
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Zoltan Dekan
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Volker Herzig
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Chun Yuen Chow
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Jacqueline Heighway
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Sau Wing Lam
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Gilles J Guillemin
- Department of Biomedical Sciences, Macquarie University, Sydney, NSW 2109, Australia; St Vincent's Centre for Applied Medical Research, Darlinghurst, NSW 2010, Australia
| | - Paul F Alewood
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Glenn F King
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia.
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12
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Moreels L, Peigneur S, Yamaguchi Y, Vriens K, Waelkens E, Zhu S, Thevissen K, Cammue BPA, Sato K, Tytgat J. Expanding the pharmacological profile of κ-hefutoxin 1 and analogues: A focus on the inhibitory effect on the oncogenic channel K v10.1. Peptides 2017; 98:43-50. [PMID: 27578329 DOI: 10.1016/j.peptides.2016.08.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Revised: 08/21/2016] [Accepted: 08/23/2016] [Indexed: 10/21/2022]
Abstract
Peptide toxins, such as scorpion peptides, are interesting lead compounds in the search for novel drugs. In this paper, the focus is on the scorpion peptide κ-hefutoxin 1. This peptide displays a cysteine-stabilized helix-loop-helix fold (CSα/α) and is known to be a weak Kv1.x inhibitor. Due to the low affinity of κ-hefutoxin 1 for these channels, it is assumed that the main target(s) of κ-hefutoxin 1 remain(s) unknown. In order to identify novel targets, electrophysiological measurements and antifungal assays were performed. The effect of κ-hefutoxin 1 was previously evaluated on a panel of 11 different voltage-gated potassium channels. Here, we extended this target screening with the oncogenic potassium channel Kv10.1. κ-Hefutoxin 1 was able to inhibit this channel in a dose-dependent manner (IC50∼26μM). Although the affinity is rather low, this is the first peptide toxin ever described to be a Kv10.1 inhibitor. The structure-activity relationship of κ-hefutoxin 1 on Kv10.1 was investigated by testing eight κ-hefutoxin 1 variants using the two-electrode voltage clamp technique. Several important amino acid residues were identified; the functional dyad residues (Tyr5 and Lys19), N-terminal residues (Gly1 and His2) and the amidated C-terminal residue (Cys22). Since the CSα/α fold is also found in a class of antifungal plant peptides, the α-hairpinines, we investigated the antifungal activity of κ-hefutoxin 1. κ-Hefutoxin 1 showed low activity against the plant pathogen Fusarium culmorum and no activity against three other yeast and fungal species, even at high concentrations (∼100μM).
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Affiliation(s)
- Lien Moreels
- Toxicology and Pharmacology, KU Leuven, Campus Gasthuisberg O&N2, Herestraat 49, PO Box 922, 3000 Leuven, Belgium.
| | - Steve Peigneur
- Toxicology and Pharmacology, KU Leuven, Campus Gasthuisberg O&N2, Herestraat 49, PO Box 922, 3000 Leuven, Belgium.
| | - Yoko Yamaguchi
- Department of Environmental Science, Fukuoka Women's University, Fukuoka 813-8529, Japan.
| | - Kim Vriens
- Centre of Microbial and Plant Genetics, KU Leuven, Kasteelpark Arenberg 20, PO Box 2460, 3001 Leuven, Belgium.
| | - Etienne Waelkens
- Laboratory of Protein Phosphorylation and Proteomics, KU Leuven, Campus Gasthuisberg, O&N1, Herestraat 49, PO Box 901, 3000 Leuven, Belgium.
| | - Shunyi Zhu
- Group of Peptide Biology and Evolution, State Key Laboratory of Integrated Management of Pest Insects & Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.
| | - Karin Thevissen
- Centre of Microbial and Plant Genetics, KU Leuven, Kasteelpark Arenberg 20, PO Box 2460, 3001 Leuven, Belgium.
| | - Bruno P A Cammue
- Centre of Microbial and Plant Genetics, KU Leuven, Kasteelpark Arenberg 20, PO Box 2460, 3001 Leuven, Belgium; VIB Department of Plant Systems Biology, Technologiepark 927, 9052 Ghent, Belgium.
| | - Kazuki Sato
- Department of Environmental Science, Fukuoka Women's University, Fukuoka 813-8529, Japan.
| | - Jan Tytgat
- Toxicology and Pharmacology, KU Leuven, Campus Gasthuisberg O&N2, Herestraat 49, PO Box 922, 3000 Leuven, Belgium.
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13
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Cázares-Ordoñez V, Pardo L. Kv10.1 potassium channel: from the brain to the tumors. Biochem Cell Biol 2017; 95:531-536. [DOI: 10.1139/bcb-2017-0062] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The KCNH1 gene encodes the Kv10.1 (Eag1) ion channel, a member of the EAG (ether-à-go-go) family of voltage-gated potassium channels. Recent studies have demonstrated that KCHN1 mutations are implicated in Temple–Baraitser and Zimmermann–Laband syndromes and other forms of developmental deficits that all present with mental retardation and epilepsy, suggesting that Kv10.1 might be important for cognitive development in humans. Although the Kv10.1 channel is mainly expressed in the mammalian brain, its ectopic expression occurs in 70% of human cancers. Cancer cells and tumors expressing Kv10.1 acquire selective advantages that favor cancer progression through molecular mechanisms that involve several cellular pathways, indicating that protein–protein interactions may be important for Kv10.1 influence in cell proliferation and tumorigenesis. Several studies on transcriptional and post-transcriptional regulation of Kv10.1 expression have shown interesting mechanistic insights about Kv10.1 role in oncogenesis, increasing the importance of identifying the cellular factors that regulate Kv10.1 expression in tumors.
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Affiliation(s)
- V. Cázares-Ordoñez
- Oncophysiology Group, Max Planck Institute of Experimental Medicine, Hermann-Rein-Strasse 3, 37075 Göttingen, Germany
- Oncophysiology Group, Max Planck Institute of Experimental Medicine, Hermann-Rein-Strasse 3, 37075 Göttingen, Germany
| | - L.A. Pardo
- Oncophysiology Group, Max Planck Institute of Experimental Medicine, Hermann-Rein-Strasse 3, 37075 Göttingen, Germany
- Oncophysiology Group, Max Planck Institute of Experimental Medicine, Hermann-Rein-Strasse 3, 37075 Göttingen, Germany
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14
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Moreels L, Peigneur S, Galan DT, De Pauw E, Béress L, Waelkens E, Pardo LA, Quinton L, Tytgat J. APETx4, a Novel Sea Anemone Toxin and a Modulator of the Cancer-Relevant Potassium Channel K V10.1. Mar Drugs 2017; 15:md15090287. [PMID: 28902151 PMCID: PMC5618426 DOI: 10.3390/md15090287] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 09/05/2017] [Accepted: 09/07/2017] [Indexed: 12/31/2022] Open
Abstract
The human ether-à-go-go channel (hEag1 or KV10.1) is a cancer-relevant voltage-gated potassium channel that is overexpressed in a majority of human tumors. Peptides that are able to selectively inhibit this channel can be lead compounds in the search for new anticancer drugs. Here, we report the activity-guided purification and electrophysiological characterization of a novel KV10.1 inhibitor from the sea anemone Anthopleura elegantissima. Purified sea anemone fractions were screened for inhibitory activity on KV10.1 by measuring whole-cell currents as expressed in Xenopus laevis oocytes using the two-microelectrode voltage clamp technique. Fractions that showed activity on Kv10.1 were further purified by RP-HPLC. The amino acid sequence of the peptide was determined by a combination of MALDI- LIFT-TOF/TOF MS/MS and CID-ESI-FT-ICR MS/MS and showed a high similarity with APETx1 and APETx3 and was therefore named APETx4. Subsequently, the peptide was electrophysiologically characterized on KV10.1. The selectivity of the toxin was investigated on an array of voltage-gated ion channels, including the cardiac human ether-à-go-go-related gene potassium channel (hERG or Kv11.1). The toxin inhibits KV10.1 with an IC50 value of 1.1 μM. In the presence of a similar toxin concentration, a shift of the activation curve towards more positive potentials was observed. Similar to the effect of the gating modifier toxin APETx1 on hERG, the inhibition of Kv10.1 by the isolated toxin is reduced at more positive voltages and the peptide seems to keep the channel in a closed state. Although the peptide also induces inhibitory effects on other KV and NaV channels, it exhibits no significant effect on hERG. Moreover, APETx4 induces a concentration-dependent cytotoxic and proapoptotic effect in various cancerous and noncancerous cell lines. This newly identified KV10.1 inhibitor can be used as a tool to further characterize the oncogenic channel KV10.1 or as a scaffold for the design and synthesis of more potent and safer anticancer drugs.
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Affiliation(s)
- Lien Moreels
- Toxicology and Pharmacology, KU Leuven, Leuven 3000, Belgium.
| | - Steve Peigneur
- Toxicology and Pharmacology, KU Leuven, Leuven 3000, Belgium.
| | - Diogo T Galan
- Toxicology and Pharmacology, KU Leuven, Leuven 3000, Belgium.
| | - Edwin De Pauw
- Laboratory of Mass Spectrometry-MolSys, University of Liege, Liege 4000, Belgium.
| | - Lászlo Béress
- Immunology and Rheumatology, Section of Peptide Chemistry, Hannover Medical School (MHH), Hannover 30625, Germany.
| | - Etienne Waelkens
- Laboratory of Protein Phosphorylation and Proteomics, KU Leuven, Leuven 3000, Belgium.
| | - Luis A Pardo
- Oncophysiology Group, Max Planck Institute for Experimental Medicine; Göttingen 37075, Germany.
| | - Loïc Quinton
- Laboratory of Mass Spectrometry-MolSys, University of Liege, Liege 4000, Belgium.
| | - Jan Tytgat
- Toxicology and Pharmacology, KU Leuven, Leuven 3000, Belgium.
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15
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Dai G, Zagotta WN. Molecular mechanism of voltage-dependent potentiation of KCNH potassium channels. eLife 2017; 6. [PMID: 28443815 PMCID: PMC5440166 DOI: 10.7554/elife.26355] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2017] [Accepted: 04/24/2017] [Indexed: 12/11/2022] Open
Abstract
EAG-like (ELK) voltage-gated potassium channels are abundantly expressed in the brain. These channels exhibit a behavior called voltage-dependent potentiation (VDP), which appears to be a specialization to dampen the hyperexitability of neurons. VDP manifests as a potentiation of current amplitude, hyperpolarizing shift in voltage sensitivity, and slowing of deactivation in response to a depolarizing prepulse. Here we show that VDP of D. rerio ELK channels involves the structural interaction between the intracellular N-terminal eag domain and C-terminal CNBHD. Combining transition metal ion FRET, patch-clamp fluorometry, and incorporation of a fluorescent noncanonical amino acid, we show that there is a rearrangement in the eag domain-CNBHD interaction with the kinetics, voltage-dependence, and ATP-dependence of VDP. We propose that the activation of ELK channels involves a slow open-state dependent rearrangement of the direct interaction between the eag domain and CNBHD, which stabilizes the opening of the channel. DOI:http://dx.doi.org/10.7554/eLife.26355.001 In humans and other animals, electrical signals trigger the heart to beat and carry information around the brain and nervous system. Particular cells can generate these signals by regulating the flow of ions into and out of the cell via proteins called ion channels. These proteins sit in the membrane that surrounds the cell and will open or close in response to specific signals. For example, an ion channel in humans called hERG allows positively-charged potassium ions to flow out of a heart cell to help the cell return to its “resting” state after producing an electrical signal. Defects in hERG can alter the rhythm at which the heart beats, leading to a serious condition called Long QT syndrome. The human hERG channel is part of a family of related channels known as the KCNH channels. These channels are made of four protein subunits that assemble to form a pore that spans the cell membrane. When a cell is resting before producing an electrical signal, KCNH channels are generally closed. However, once an electrical signal starts, the flow of ions through other ion channels in the cell membrane changes an electrical property across the membrane known as the “voltage”. This change in voltage causes KCNH channels to open. Dai and Zagotta studied how a KCNH channel known as ELK from zebrafish responds to changes in membrane voltage. The experiments show that the manner in which ELK channels respond to the voltage is due to changes in how the subunits interact in the part of the channel that lies inside the cell. Further experiments using several new techniques reveal in much more detail how the shape of the channel alters as the voltage changes. These new techniques could also be used to observe how other KCNH channels in the heart and brain change shape in response to changes in voltage. This could lead to the design of new drugs to treat heart and neurological diseases. DOI:http://dx.doi.org/10.7554/eLife.26355.002
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Affiliation(s)
- Gucan Dai
- Department of Physiology and Biophysics, University of Washington, Seattle, United States
| | - William N Zagotta
- Department of Physiology and Biophysics, University of Washington, Seattle, United States
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16
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Bernsteiner H, Bründl M, Stary-Weinzinger A. Dynamics of the EAG1 K + channel selectivity filter assessed by molecular dynamics simulations. Biochem Biophys Res Commun 2017; 484:107-112. [PMID: 28109880 PMCID: PMC6531291 DOI: 10.1016/j.bbrc.2017.01.064] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Accepted: 01/13/2017] [Indexed: 01/14/2023]
Abstract
EAG1 channels belong to the KCNH family of voltage gated potassium channels. They are expressed in several brain regions and increased expression is linked to certain cancer types. Recent cryo-EM structure determination finally revealed the structure of these channels in atomic detail, allowing computational investigations. In this study, we performed molecular dynamics simulations to investigate the ion binding sites and the dynamical behavior of the selectivity filter. Our simulations suggest that sites S2 and S4 form stable ion binding sites, while ions placed at sites S1 and S3 rapidly switched to sites S2 and S4. Further, ions tended to dissociate away from S0 within less than 20 ns, due to increased filter flexibility. This was followed by water influx from the extracellular side, leading to a widening of the filter in this region, and likely non-conductive filter configurations. Simulations with the inactivation-enhancing mutant Y464A or Na+ ions lead to trapped water molecules behind the SF, suggesting that these simulations captured early conformational changes linked to C-type inactivation.
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Affiliation(s)
- Harald Bernsteiner
- Department of Pharmacology and Toxicology, University of Vienna, Althanstraße 14, 1090 Vienna, Austria
| | - Michael Bründl
- Department of Pharmacology and Toxicology, University of Vienna, Althanstraße 14, 1090 Vienna, Austria
| | - Anna Stary-Weinzinger
- Department of Pharmacology and Toxicology, University of Vienna, Althanstraße 14, 1090 Vienna, Austria.
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17
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Cullin 7 mediates proteasomal and lysosomal degradations of rat Eag1 potassium channels. Sci Rep 2017; 7:40825. [PMID: 28098200 PMCID: PMC5241692 DOI: 10.1038/srep40825] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Accepted: 12/12/2016] [Indexed: 11/08/2022] Open
Abstract
Mammalian Eag1 (Kv10.1) potassium (K+) channels are widely expressed in the brain. Several mutations in the gene encoding human Eag1 K+ channel have been associated with congenital neurodevelopmental anomalies. Currently very little is known about the molecules mediating protein synthesis and degradation of Eag1 channels. Herein we aim to ascertain the protein degradation mechanism of rat Eag1 (rEag1). We identified cullin 7 (Cul7), a member of the cullin-based E3 ubiquitin ligase family, as a novel rEag1 binding partner. Immunoprecipitation analyses confirmed the interaction between Cul7 and rEag1 in heterologous cells and neuronal tissues. Cul7 and rEag1 also exhibited significant co-localization at synaptic regions in neurons. Over-expression of Cul7 led to reduced protein level, enhanced ubiquitination, accelerated protein turn-over, and decreased current density of rEag1 channels. We provided further biochemical and morphological evidence suggesting that Cul7 targeted endoplasmic reticulum (ER)- and plasma membrane-localized rEag1 to the proteasome and the lysosome, respectively, for protein degradation. Cul7 also contributed to protein degradation of a disease-associated rEag1 mutant. Together, these results indicate that Cul7 mediates both proteasomal and lysosomal degradations of rEag1. Our findings provide a novel insight to the mechanisms underlying ER and peripheral protein quality controls of Eag1 channels.
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18
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Choi HJ, Park H, Zhang L, Kim JH, Kim YA, Yang JY, Pei YF, Tian Q, Shen H, Hwang JY, Deng HW, Cho NH, Shin CS. Genome-wide association study in East Asians suggests UHMK1 as a novel bone mineral density susceptibility gene. Bone 2016; 91:113-21. [PMID: 27424934 DOI: 10.1016/j.bone.2016.07.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Revised: 07/11/2016] [Accepted: 07/13/2016] [Indexed: 12/20/2022]
Abstract
To identify genetic variants that influence bone mineral density (BMD) in East Asians, we performed a quantitative trait analysis of lumbar spine, total hip and femoral neck BMD in a Korean population-based cohort (N=2729) and follow-up replication analysis in a Chinese Han population and two Caucasian populations (N=1547, 2250 and 987, respectively). From the meta-analysis of the stage 1 discovery analysis and stage 2 replication analysis, we identified four BMD loci that reached near-genome-wide significance level (P<5×10(-7)). One locus on 1q23 (UHMK1, rs16863247, P=4.1×10(-7) for femoral neck BMD and P=3.2×10(-6) for total hip BMD) was a novel BMD signal. Interestingly, rs16863247 was very rare in Caucasians (minor allele frequency<0.01), indicating that this association could be specific to East Asians. In gender specific analysis, rs1160574 on 1q32 (KCNH1) was associated with femoral neck BMD (P=2.1×10(-7)) in female subjects. rs9371538 in the known BMD region on 6q25 ESR1 was associated with lumbar spine BMD (P=5.6×10(-9)). rs7776725 in the known BMD region on 7q31 WTN16 was associated with total hip BMD (P=8.6×10(-9)). In osteoblasts, endogenous UHMK1 expression was increased during differentiation and UHMK1 knockdown decreased its differentiation, while UHMK1 overexpression increased its differentiation. In osteoclasts, endogenous UHMK1 expression was decreased during differentiation and UHMK1 knockdown increased its differentiation, while UHMK1 overexpression decreased its differentiation. In conclusion, our genome-wide association study identified the UHMK1 gene as a novel BMD locus specific to East Asians. Functional studies suggest a role of UHMK1 on regulation of osteoblasts and osteoclasts.
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Affiliation(s)
- Hyung Jin Choi
- Department of Anatomy, Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Hyojung Park
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Lei Zhang
- Center for Genetic Epidemiology and Genomics, School of Public Health, Soochow University, Jiangsu, PR China
| | - Jung Hee Kim
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Ye An Kim
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Jae-Yeon Yang
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Yu-Fang Pei
- Department of Epidemiology, School of Public Health, Soochow University, Jiangsu, PR China
| | - Qing Tian
- Department of Biostatistics and Bioinformatics, Tulane University, New Orleans, USA
| | - Hui Shen
- Department of Biostatistics and Bioinformatics, Tulane University, New Orleans, USA
| | - Joo-Yeon Hwang
- Center for Genome Science, National Institute of Health, Osong Health Technology Administration Complex, Cheongju, Republic of Korea
| | - Hong-Wen Deng
- Department of Biostatistics and Bioinformatics, Tulane University, New Orleans, USA
| | - Nam H Cho
- Department of Preventive Medicine, Ajou University School of Medicine, Suwon, Republic of Korea.
| | - Chan Soo Shin
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea.
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19
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Lörinczi E, Helliwell M, Finch A, Stansfeld PJ, Davies NW, Mahaut-Smith M, Muskett FW, Mitcheson JS. Calmodulin Regulates Human Ether à Go-Go 1 (hEAG1) Potassium Channels through Interactions of the Eag Domain with the Cyclic Nucleotide Binding Homology Domain. J Biol Chem 2016; 291:17907-18. [PMID: 27325704 PMCID: PMC5016179 DOI: 10.1074/jbc.m116.733576] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Indexed: 11/24/2022] Open
Abstract
The ether à go-go family of voltage-gated potassium channels is structurally distinct. The N terminus contains an eag domain (eagD) that contains a Per-Arnt-Sim (PAS) domain that is preceded by a conserved sequence of 25–27 amino acids known as the PAS-cap. The C terminus contains a region with homology to cyclic nucleotide binding domains (cNBHD), which is directly linked to the channel pore. The human EAG1 (hEAG1) channel is remarkably sensitive to inhibition by intracellular calcium (Ca2+i) through binding of Ca2+-calmodulin to three sites adjacent to the eagD and cNBHD. Here, we show that the eagD and cNBHD interact to modulate Ca2+-calmodulin as well as voltage-dependent gating. Sustained elevation of Ca2+i resulted in an initial profound inhibition of hEAG1 currents, which was followed by a phase when current amplitudes partially recovered, but activation gating was slowed and shifted to depolarized potentials. Deletion of either the eagD or cNBHD abolished the inhibition by Ca2+i. However, deletion of just the PAS-cap resulted in a >15-fold potentiation in response to elevated Ca2+i. Mutations of residues at the interface between the eagD and cNBHD have been linked to human cancer. Glu-600 on the cNBHD, when substituted with residues with a larger volume, resulted in hEAG1 currents that were profoundly potentiated by Ca2+i in a manner similar to the ΔPAS-cap mutant. These findings provide the first evidence that eagD and cNBHD interactions are regulating Ca2+-dependent gating and indicate that the binding of the PAS-cap with the cNBHD is required for the closure of the channels upon CaM binding.
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Affiliation(s)
- Eva Lörinczi
- From the Department of Molecular and Cell Biology, University of Leicester, Leicester LE1 9HN
| | - Matthew Helliwell
- From the Department of Molecular and Cell Biology, University of Leicester, Leicester LE1 9HN, the School of Physiology and Pharmacology, University of Bristol, Bristol BS5 1TD, and
| | - Alina Finch
- From the Department of Molecular and Cell Biology, University of Leicester, Leicester LE1 9HN
| | - Phillip J Stansfeld
- the Department of Biochemistry, University of Oxford, Oxford OX1 3QU, United Kingdom
| | - Noel W Davies
- From the Department of Molecular and Cell Biology, University of Leicester, Leicester LE1 9HN
| | - Martyn Mahaut-Smith
- From the Department of Molecular and Cell Biology, University of Leicester, Leicester LE1 9HN
| | - Frederick W Muskett
- From the Department of Molecular and Cell Biology, University of Leicester, Leicester LE1 9HN
| | - John S Mitcheson
- From the Department of Molecular and Cell Biology, University of Leicester, Leicester LE1 9HN,
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20
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Hsu PH, Chiu YC, Lin TF, Jeng CJ. Ca(2+)-binding protein centrin 4 is a novel binding partner of rat Eag1 K(+) channels. FEBS Open Bio 2016; 6:349-57. [PMID: 27239447 PMCID: PMC4821352 DOI: 10.1002/2211-5463.12045] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Revised: 02/14/2016] [Accepted: 02/16/2016] [Indexed: 01/14/2023] Open
Abstract
Eag1 is neuron-specific K(+) channel abundantly expressed in the brain and retina. Subcellular localization and physiological analyses in neurons reveal that Eag1 may participate in Ca(2+)-signaling processes in the synapse. Here, we searched for rat Eag1 (rEag1)-binding proteins that may contribute to Ca(2+) regulation of the K(+) channel. Yeast two-hybrid screening identified centrin 4, a member of the centrin family of Ca(2+)-binding proteins. GST pull-down and immunoprecipitation assays in brain and retina lysates confirm the interaction of centrin with rEag1 in neurons. Centrin 4 binds to rEag1 in the absence of Ca(2+). Raising Ca(2+) concentration enhances the association efficiency of centrin 4 and rEag1, and is required for the suppression of rEag1 currents by centrin 4. Altogether, our data suggest that centrin 4 is a novel binding partner that may contribute to Ca(2+) regulation of rEag1 in neurons.
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Affiliation(s)
- Po-Hao Hsu
- Institute of Anatomy and Cell Biology School of Medicine National Yang-Ming University Taipei Taiwan
| | - Yi-Chih Chiu
- Institute of Anatomy and Cell Biology School of Medicine National Yang-Ming University Taipei Taiwan
| | - Ting-Feng Lin
- Institute of Anatomy and Cell Biology School of Medicine National Yang-Ming University Taipei Taiwan
| | - Chung-Jiuan Jeng
- Institute of Anatomy and Cell Biology School of Medicine National Yang-Ming University Taipei Taiwan; Brain Research Center National Yang-Ming University Taipei Taiwan
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21
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Heine M, Ciuraszkiewicz A, Voigt A, Heck J, Bikbaev A. Surface dynamics of voltage-gated ion channels. Channels (Austin) 2016; 10:267-81. [PMID: 26891382 DOI: 10.1080/19336950.2016.1153210] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Neurons encode information in fast changes of the membrane potential, and thus electrical membrane properties are critically important for the integration and processing of synaptic inputs by a neuron. These electrical properties are largely determined by ion channels embedded in the membrane. The distribution of most ion channels in the membrane is not spatially uniform: they undergo activity-driven changes in the range of minutes to days. Even in the range of milliseconds, the composition and topology of ion channels are not static but engage in highly dynamic processes including stochastic or activity-dependent transient association of the pore-forming and auxiliary subunits, lateral diffusion, as well as clustering of different channels. In this review we briefly discuss the potential impact of mobile sodium, calcium and potassium ion channels and the functional significance of this for individual neurons and neuronal networks.
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Affiliation(s)
- Martin Heine
- a RG Molecular Physiology, Leibniz Institute for Neurobiology, Center for Behavioral Brain Science, Otto-von-Guericke-University of Magdeburg , Magdeburg , Germany
| | - Anna Ciuraszkiewicz
- a RG Molecular Physiology, Leibniz Institute for Neurobiology, Center for Behavioral Brain Science, Otto-von-Guericke-University of Magdeburg , Magdeburg , Germany
| | - Andreas Voigt
- b Lehrstuhl Systemverfahrenstechnik, Otto-von-Guericke-University of Magdeburg , Magdeburg , Germany
| | - Jennifer Heck
- a RG Molecular Physiology, Leibniz Institute for Neurobiology, Center for Behavioral Brain Science, Otto-von-Guericke-University of Magdeburg , Magdeburg , Germany
| | - Arthur Bikbaev
- a RG Molecular Physiology, Leibniz Institute for Neurobiology, Center for Behavioral Brain Science, Otto-von-Guericke-University of Magdeburg , Magdeburg , Germany
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Kv10.1 K+ channel: from physiology to cancer. Pflugers Arch 2016; 468:751-62. [DOI: 10.1007/s00424-015-1784-3] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Revised: 12/11/2015] [Accepted: 12/27/2015] [Indexed: 12/18/2022]
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Acuña-Macías I, Vera E, Vázquez-Sánchez AY, Mendoza-Garrido ME, Camacho J. Differential regulation of human Eag1 channel expression by serum and epidermal growth factor in lung and breast cancer cells. Onco Targets Ther 2015; 8:2959-65. [PMID: 26527881 PMCID: PMC4621197 DOI: 10.2147/ott.s85504] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Oncogenic ether à-go-go-1 (Eag1) potassium channels are overexpressed in most primary human solid tumors. Low oxygen and nutrient/growth factor concentrations play critical roles in tumorigenesis. However, the mechanisms by which tumor cells survive and proliferate under growth factor-depleted conditions remain elusive. Here, we investigated whether serum-deprived conditions and epidermal growth factor (EGF) regulate Eag1 expression in human lung and breast cancer cells. The human cancer cell lines A549 and MCF-7 (from the lungs and breast, respectively) were obtained from the American Type Culture Collection and cultured following the manufacturer’s recommendations. Eag1 gene and protein expression were studied by real-time PCR and immunocytochemistry, respectively. Cell proliferation was evaluated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, and ERK1/2 phosphorylation was investigated by Western blot. Serum-deprived conditions increased Eag1 mRNA and protein expression in both cell lines. This Eag1 upregulation was prevented by EGF and the ERK1/2 inhibitor U0126 in only lung cancer cells; vascular endothelial growth factor did not prevent Eag1 upregulation. Our results suggest that Eag1 may act as a survival and mitogenic factor under low-serum and nutrient conditions and may be a clinical target during the early stages of tumor development.
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Affiliation(s)
- Isabel Acuña-Macías
- Department of Pharmacology, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Mexico City, Mexico
| | - Eunice Vera
- Department of Pharmacology, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Mexico City, Mexico
| | - Alma Yolanda Vázquez-Sánchez
- Department of Pharmacology, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Mexico City, Mexico
| | - María Eugenia Mendoza-Garrido
- Department of Physiology, Biophysics and Neurosciences, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Mexico City, Mexico
| | - Javier Camacho
- Department of Pharmacology, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Mexico City, Mexico
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Martínez R, Stühmer W, Martin S, Schell J, Reichmann A, Rohde V, Pardo L. Analysis of the expression of Kv10.1 potassium channel in patients with brain metastases and glioblastoma multiforme: impact on survival. BMC Cancer 2015; 15:839. [PMID: 26530050 PMCID: PMC4632660 DOI: 10.1186/s12885-015-1848-y] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Accepted: 10/26/2015] [Indexed: 01/01/2023] Open
Abstract
Background Kv10.1, a voltage-gated potassium channel only detected in the healthy brain, was found to be aberrantly expressed in extracerebral cancers. Investigations of Kv10.1 in brain metastasis and glioblastoma multiforme (GBM) are lacking. Methods We analyzed the expression of Kv10.1 by immunohistochemistry in these brain tumors (75 metastasis from different primary tumors, 71 GBM patients) and the influence of a therapy with tricyclic antidepressants (which are Kv10.1 blockers) on survival. We also investigated Kv10.1 expression in the corresponding primary carcinomas of metastases patients. Results We observed positive Kv10.1 expression in 85.3 % of the brain metastases and in 77.5 % of GBMs. Patients with brain metastases, showing low Kv10.1 expression, had a significantly longer overall survival compared to those patients with high Kv10.1 expression. Metastases patients displaying low Kv10.1 expression and also receiving tricyclic antidepressants showed a significantly longer median overall survival as compared to untreated patients. Conclusions Our data show that Kv10.1 is not only highly expressed in malignant tumors outside CNS, but also in the most frequent cerebral cancer entities, metastasis and GBM, which remain incurable in spite of aggressive multimodal therapies. Our results extend the correlation between dismal prognosis and Kv10.1 expression to patients with brain metastases or GBMs and, moreover, they strongly suggest a role of tricyclic antidepressants for personalized therapy of brain malignancies.
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Affiliation(s)
- Ramón Martínez
- Department of Neurosurgery, University of Goettingen, Robert-Koch-Str. 40, Goettingen, 37075, Germany.
| | - Walter Stühmer
- Department of Molecular Biology of Neuronal Signals, Max-Planck Institute for Experimental Medicine, Hermann-Rein-Str. 3, Goettingen, 37075, Germany.
| | - Sabine Martin
- Department of Molecular Biology of Neuronal Signals, Max-Planck Institute for Experimental Medicine, Hermann-Rein-Str. 3, Goettingen, 37075, Germany.
| | - Julian Schell
- Department of Neurosurgery, University of Goettingen, Robert-Koch-Str. 40, Goettingen, 37075, Germany.
| | - Andrea Reichmann
- Department of Neurosurgery, University of Goettingen, Robert-Koch-Str. 40, Goettingen, 37075, Germany.
| | - Veit Rohde
- Department of Neurosurgery, University of Goettingen, Robert-Koch-Str. 40, Goettingen, 37075, Germany.
| | - Luis Pardo
- Department of Molecular Biology of Neuronal Signals, Max-Planck Institute for Experimental Medicine, Hermann-Rein-Str. 3, Goettingen, 37075, Germany.
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Ramos Gomes F, Romaniello V, Sánchez A, Weber C, Narayanan P, Psol M, Pardo LA. Alternatively Spliced Isoforms of KV10.1 Potassium Channels Modulate Channel Properties and Can Activate Cyclin-dependent Kinase in Xenopus Oocytes. J Biol Chem 2015; 290:30351-65. [PMID: 26518875 PMCID: PMC4683259 DOI: 10.1074/jbc.m115.668749] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Indexed: 12/18/2022] Open
Abstract
KV10.1 is a voltage-gated potassium channel expressed selectively in the mammalian brain but also aberrantly in cancer cells. In this study we identified short splice variants of KV10.1 resulting from exon-skipping events (E65 and E70) in human brain and cancer cell lines. The presence of the variants was confirmed by Northern blot and RNase protection assays. Both variants completely lacked the transmembrane domains of the channel and produced cytoplasmic proteins without channel function. In a reconstituted system, both variants co-precipitated with the full-length channel and induced a robust down-regulation of KV10.1 current when co-expressed with the full-length form, but their effect was mechanistically different. E65 required a tetramerization domain and induced a reduction in the overall expression of full-length KV10.1, whereas E70 mainly affected its glycosylation pattern. E65 triggered the activation of cyclin-dependent kinases in Xenopus laevis oocytes, suggesting a role in cell cycle control. Our observations highlight the relevance of noncanonical functions for the oncogenicity of KV10.1, which need to be considered when ion channels are targeted for cancer therapy.
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Affiliation(s)
| | - Vincenzo Romaniello
- the Oncophysiology Group, Max Planck Institute of Experimental Medicine, Hermann-Rein-Strasse 3, 37075 Göttingen, Germany
| | - Araceli Sánchez
- the Oncophysiology Group, Max Planck Institute of Experimental Medicine, Hermann-Rein-Strasse 3, 37075 Göttingen, Germany
| | - Claudia Weber
- From the Department of Molecular Biology of Neuronal Signals and
| | | | - Maryna Psol
- From the Department of Molecular Biology of Neuronal Signals and
| | - Luis A Pardo
- the Oncophysiology Group, Max Planck Institute of Experimental Medicine, Hermann-Rein-Strasse 3, 37075 Göttingen, Germany
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Kortüm F, Caputo V, Bauer CK, Stella L, Ciolfi A, Alawi M, Bocchinfuso G, Flex E, Paolacci S, Dentici ML, Grammatico P, Korenke GC, Leuzzi V, Mowat D, Nair LDV, Nguyen TTM, Thierry P, White SM, Dallapiccola B, Pizzuti A, Campeau PM, Tartaglia M, Kutsche K. Mutations in KCNH1 and ATP6V1B2 cause Zimmermann-Laband syndrome. Nat Genet 2015; 47:661-7. [DOI: 10.1038/ng.3282] [Citation(s) in RCA: 139] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Accepted: 03/23/2015] [Indexed: 12/16/2022]
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Involvement of potassium channels in the progression of cancer to a more malignant phenotype. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2014; 1848:2477-92. [PMID: 25517985 DOI: 10.1016/j.bbamem.2014.12.008] [Citation(s) in RCA: 95] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Revised: 12/01/2014] [Accepted: 12/08/2014] [Indexed: 12/22/2022]
Abstract
Potassium channels are a diverse group of pore-forming transmembrane proteins that selectively facilitate potassium flow through an electrochemical gradient. They participate in the control of the membrane potential and cell excitability in addition to different cell functions such as cell volume regulation, proliferation, cell migration, angiogenesis as well as apoptosis. Because these physiological processes are essential for the correct cell function, K+ channels have been associated with a growing number of diseases including cancer. In fact, different K+ channel families such as the voltage-gated K+ channels, the ether à-go-go K+ channels, the two pore domain K+ channels and the Ca2+-activated K+ channels have been associated to tumor biology. Potassium channels have a role in neoplastic cell-cycle progression and their expression has been found abnormal in many types of tumors and cancer cells. In addition, the expression and activity of specific K+ channels have shown a significant correlation with the tumor malignancy grade. The aim of this overview is to summarize published data on K+ channels that exhibit oncogenic properties and have been linked to a more malignant cancer phenotype. This article is part of a Special Issue entitled: Membrane channels and transporters in cancers.
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Mortensen LS, Schmidt H, Farsi Z, Barrantes-Freer A, Rubio ME, Ufartes R, Eilers J, Sakaba T, Stühmer W, Pardo LA. KV 10.1 opposes activity-dependent increase in Ca²⁺ influx into the presynaptic terminal of the parallel fibre-Purkinje cell synapse. J Physiol 2014; 593:181-96. [PMID: 25556795 DOI: 10.1113/jphysiol.2014.281600] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Accepted: 10/13/2014] [Indexed: 12/14/2022] Open
Abstract
KEY POINTS Voltage-gated KV 10.1 potassium channels are widely expressed in the mammalian brain but their function remains poorly understood. We report that KV 10.1 is enriched in the presynaptic terminals and does not take part in somatic action potentials. In parallel fibre synapses in the cerebellar cortex, we find that KV 10.1 regulates Ca(2+) influx and neurotransmitter release during repetitive high-frequency activity. Our results describe the physiological role of mammalian KV 10.1 for the first time and help understand the fine-tuning of synaptic transmission. The voltage-gated potassium channel KV 10.1 (Eag1) is widely expressed in the mammalian brain, but its physiological function is not yet understood. Previous studies revealed highest expression levels in hippocampus and cerebellum and suggested a synaptic localization of the channel. The distinct activation kinetics of KV 10.1 indicate a role during repetitive activity of the cell. Here, we confirm the synaptic localization of KV 10.1 both biochemically and functionally and that the channel is sufficiently fast at physiological temperature to take part in repolarization of the action potential (AP). We studied the role of the channel in cerebellar physiology using patch clamp and two-photon Ca(2+) imaging in KV 10.1-deficient and wild-type mice. The excitability and action potential waveform recorded at granule cell somata was unchanged, while Ca(2+) influx into axonal boutons was enhanced in mutants in response to stimulation with three APs, but not after a single AP. Furthermore, mutants exhibited a frequency-dependent increase in facilitation at the parallel fibre-Purkinje cell synapse at high firing rates. We propose that KV 10.1 acts as a modulator of local AP shape specifically during high-frequency burst firing when other potassium channels suffer cumulative inactivation.
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Affiliation(s)
- Lena Sünke Mortensen
- Max-Planck-Institute of Experimental Medicine, 37075, Göttingen, Germany; International Max Planck Research School Neurosciences, 37077, Göttingen, Germany
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Jiménez-Garduño AM, Mitkovski M, Alexopoulos IK, Sánchez A, Stühmer W, Pardo LA, Ortega A. KV10.1 K+-channel plasma membrane discrete domain partitioning and its functional correlation in neurons. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2014; 1838:921-31. [DOI: 10.1016/j.bbamem.2013.11.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2013] [Revised: 10/27/2013] [Accepted: 11/05/2013] [Indexed: 12/25/2022]
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Hippocampal ether-à-go-go1 potassium channels blockade: Effects in the startle reflex and prepulse inhibition. Neurosci Lett 2014; 559:13-7. [DOI: 10.1016/j.neulet.2013.11.026] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Revised: 11/13/2013] [Accepted: 11/16/2013] [Indexed: 12/19/2022]
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Abstract
Potassium channels are transmembrane proteins that selectively facilitate the flow of potassium ions down an electrochemical gradient. These molecules have been studied in great detail in the context of cell excitability, but their roles in less cell type-specific functions, such as cell proliferation, angiogenesis or cell migration, have only recently been assessed. Moreover, the importance of these channels for tumour biology has become evident. This, coupled with the fact that they are accessible proteins and that their pharmacology is well characterized, has increased the interest in investigating potassium channels as therapeutic targets in cancer patients.
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Affiliation(s)
- Luis A Pardo
- Oncophysiology Group, Max-Planck-Institute of Experimental Medicine, Hermann-Rein-Strasse 3, 37075 Göttingen, Germany
| | - Walter Stühmer
- Department of Molecular Biology of Neuronal Signals, Max-Planck-Institute of Experimental Medicine, Hermann-Rein-Strasse 3, 37075 Göttingen, Germany
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Lazzarini M, Martin S, Mitkovski M, Vozari RR, Stühmer W, Bel ED. Doxycycline restrains glia and confers neuroprotection in a 6-OHDA Parkinson model. Glia 2013; 61:1084-100. [PMID: 23595698 DOI: 10.1002/glia.22496] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Accepted: 02/22/2013] [Indexed: 01/09/2023]
Abstract
Neuron-glia interactions play a key role in maintaining and regulating the central nervous system. Glial cells are implicated in the function of dopamine neurons and regulate their survival and resistance to injury. Parkinson's disease is characterized by the loss of dopamine neurons in the substantia nigra pars compacta, decreased striatal dopamine levels and consequent onset of extrapyramidal motor dysfunction. Parkinson's disease is a common chronic, neurodegenerative disorder with no effective protective treatment. In the 6-OHDA mouse model of Parkinson's disease, doxycycline administered at a dose that both induces/represses conditional transgene expression in the tetracycline system, mitigates the loss of dopaminergic neurons in the substantia nigra compacta and nerve terminals in the striatum. This protective effect was associated with: (1) a reduction of microglia in normal mice as a result of doxycycline administration per se; (2) a decrease in the astrocyte and microglia response to the neurotoxin 6-OHDA in the globus pallidus and substantia nigra compacta, and (3) the astrocyte reaction in the striatum. Our results suggest that doxycycline blocks 6-OHDA neurotoxicity in vivo by inhibiting microglial and astrocyte expression. This action of doxycycline in nigrostriatal dopaminergic neuron protection is consistent with a role of glial cells in Parkinson's disease neurodegeneration. The neuroprotective effect of doxycycline may be useful in preventing or slowing the progression of Parkinson's disease and other neurodegenerative diseases linked to glia function.
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Affiliation(s)
- Marcio Lazzarini
- Department of Morphology, Physiology and Pathology, School of Odontology of Ribeirão Preto (FORP), University of São Paulo (USP), Ribeirão Preto, SP, Brazil
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Ufartes R, Schneider T, Mortensen LS, de Juan Romero C, Hentrich K, Knoetgen H, Beilinson V, Moebius W, Tarabykin V, Alves F, Pardo LA, Rawlins JNP, Stuehmer W. Behavioural and functional characterization of Kv10.1 (Eag1) knockout mice. Hum Mol Genet 2013; 22:2247-62. [PMID: 23424202 PMCID: PMC3652421 DOI: 10.1093/hmg/ddt076] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Kv10.1 (Eag1), member of the Kv10 family of voltage-gated potassium channels, is preferentially expressed in adult brain. The aim of the present study was to unravel the functional role of Kv10.1 in the brain by generating knockout mice, where the voltage sensor and pore region of Kv10.1 were removed to render non-functional proteins through deletion of exon 7 of the KCNH1 gene using the ‘3 Lox P strategy’. Kv10.1-deficient mice show no obvious alterations during embryogenesis and develop normally to adulthood; cortex, hippocampus and cerebellum appear anatomically normal. Other tests, including general health screen, sensorimotor functioning and gating, anxiety, social behaviour, learning and memory did not show any functional aberrations in Kv10.1 null mice. Kv10.1 null mice display mild hyperactivity and longer-lasting haloperidol-induced catalepsy, but there was no difference between genotypes in amphetamine sensitization and withdrawal, reactivity to apomorphine and haloperidol in the prepulse inhibition tests or to antidepressants in the haloperidol-induced catalepsy. Furthermore, electrical properties of Kv10.1 in cerebellar Purkinje cells did not show any difference between genotypes. Bearing in mind that Kv10.1 is overexpressed in over 70% of all human tumours and that its inhibition leads to a reduced tumour cell proliferation, the fact that deletion of Kv10.1 does not show a marked phenotype is a prerequisite for utilizing Kv10.1 blocking and/or reduction techniques, such as siRNA, to treat cancer.
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Affiliation(s)
- Roser Ufartes
- Department of Molecular Biology of Neuronal Signals, Max-Planck-Institute for Experimental Medicine, Hermann-Rein-Str. 3, Göttingen 37077, Germany.
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p38 MAPK regulates the expression of ether à go-go potassium channel in human osteosarcoma cells. Radiol Oncol 2013; 47:42-9. [PMID: 23450231 PMCID: PMC3573833 DOI: 10.2478/v10019-012-0043-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2012] [Accepted: 05/30/2012] [Indexed: 12/14/2022] Open
Abstract
Background The ether à go-go (Eag) channel has been shown to be overexpressed in a variety of cancers. However, the expression and function of Eag in osteosarcoma are poorly understood. In addition, the molecular mechanisms responsible for Eag overexpression in cancer cells remain unclear. Methods The expression of Eag in human osteosarcoma cell line MG-63 was detected by reverse transcription polymerase chain reaction (RT-PCR) and Western blot analysis. The effect of Eag inhibition on MG-63 cell proliferation was assessed in vitro. The effect of short hairpin RNA (shRNA) mediated knockdown of Eag on osteosarcoma growth was evaluated in xenograft model in vivo. The activation of mitogen-activated protein kinase (MAPK) pathway and p53 in MG-63 cells was detected by Western blot analysis. Results Eag was overexpressed in MG-63 cells. Imipramine or Eag shRNA significantly suppressed the proliferation of MG-63 cells in vitro and in vivo. MG-63 cell proliferation was specifically inhibited by p38 MAPK inhibitor SB203580 or small interference RNA (siRNA). The inhibition of p38 MAPK activation by SB203580 or siRNA reduced Eag protein level but increased p53 protein level. Moreover, the activation of p53 by nutlin-3 induced cell growth arrest in MG-63 cells and reduced Eag protein level, while the inactivation of p53 by pifithrin-alpha (PFT-α) promoted MG-63 cell growth and increased Eag protein expression. Conclusions Eag channel functions as an oncogene to promote the proliferation of human osteosarocma cells. Furthermore, the high expression of Eag in osteosarcoma cells is regulated by p38 MAPK/p53 pathway.
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Garg V, Stary-Weinzinger A, Sanguinetti MC. ICA-105574 interacts with a common binding site to elicit opposite effects on inactivation gating of EAG and ERG potassium channels. Mol Pharmacol 2013; 83:805-13. [PMID: 23319419 DOI: 10.1124/mol.112.084384] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Rapid and voltage-dependent inactivation greatly attenuates outward currents in ether-a-go-go-related gene (ERG) K(+) channels. In contrast, inactivation of related ether-a-go-go (EAG) K(+) channels is very slow and minimally reduces outward currents. ICA-105574 (ICA, or 3-nitro-N-[4-phenoxyphenyl]-benzamide) has opposite effects on inactivation of these two channel types. Although ICA greatly attenuates ERG inactivation by shifting its voltage dependence to more positive potentials, it enhances the rate and extent of EAG inactivation without altering its voltage dependence. Here, we investigate whether the inverse functional response to ICA in EAG and ERG channels is related to differences in ICA binding site or to intrinsic mechanisms of inactivation. Molecular modeling coupled with site-directed mutagenesis suggests that ICA binds in a channel-specific orientation to a hydrophobic pocket bounded by the S5/pore helix/S6 of one subunit and S6 of an adjacent subunit. ICA is a mixed agonist of mutant EAG and EAG/ERG chimera channels that inactivate by a combination of slow and fast mechanisms. With the exception of three residues, the specific amino acids that form the putative binding pocket for ICA in ERG are conserved in EAG. Mutations introduced into EAG to replicate the ICA binding site in ERG did not alter the functional response to ICA. Together these findings suggest that ICA binds to the same site in EAG and ERG channels to elicit opposite functional effects. The resultant agonist or antagonist activity is determined solely by channel-specific differences in the mechanisms of inactivation gating.
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Affiliation(s)
- Vivek Garg
- Nora Eccles Harrison Cardiovascular Research & Training Institute, Department of Physiology, University of Utah, Salt Lake City, Utah 84112, USA
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Garg V, Sachse FB, Sanguinetti MC. Tuning of EAG K(+) channel inactivation: molecular determinants of amplification by mutations and a small molecule. ACTA ACUST UNITED AC 2012; 140:307-24. [PMID: 22930803 PMCID: PMC3434097 DOI: 10.1085/jgp.201210826] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Ether-à-go-go (EAG) and EAG-related gene (ERG) K+ channels are close homologues but differ markedly in their gating properties. ERG1 channels are characterized by rapid and extensive C-type inactivation, whereas mammalian EAG1 channels were previously considered noninactivating. Here, we show that human EAG1 channels exhibit an intrinsic voltage-dependent slow inactivation that is markedly enhanced in rate and extent by 1–10 µM 3-nitro-N-(4-phenoxyphenyl) benzamide, or ICA105574 (ICA). This compound was previously reported to have the opposite effect on ERG1 channels, causing an increase in current magnitude by inhibition of C-type inactivation. The voltage dependence of 2 µM ICA-induced inhibition of EAG1 current was half-maximal at −73 mV, 62 mV negative to the half-point for channel activation. This finding suggests that current inhibition by the drug is mediated by enhanced inactivation and not open-channel block, where the voltage half-points for current inhibition and channel activation are predicted to overlap, as we demonstrate for clofilium and astemizole. The mutation Y464A in the S6 segment also induced inactivation of EAG1, with a time course and voltage dependence similar to that caused by 2 µM ICA. Several Markov models were investigated to describe gating effects induced by multiple concentrations of the drug and the Y464A mutation. Models with the smallest fit error required both closed- and open-state inactivation. Unlike typical C-type inactivation, the rate of Y464A- and ICA-induced inactivation was not decreased by external tetraethylammonium or elevated [K+]e. EAG1 channel inactivation introduced by Y464A was prevented by additional mutation of a nearby residue located in the S5 segment (F359A) or pore helix (L434A), suggesting a tripartite molecular model where interactions between single residues in S5, S6, and the pore helix modulate inactivation of EAG1 channels.
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Affiliation(s)
- Vivek Garg
- Department of Physiology, University of Utah, Salt Lake City, UT 84112, USA
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Stengel R, Rivera-Milla E, Sahoo N, Ebert C, Bollig F, Heinemann SH, Schönherr R, Englert C. Kcnh1 voltage-gated potassium channels are essential for early zebrafish development. J Biol Chem 2012; 287:35565-35575. [PMID: 22927438 PMCID: PMC3471731 DOI: 10.1074/jbc.m112.363978] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
The Kcnh1 gene encodes a voltage-gated potassium channel highly expressed in neurons and involved in tumor cell proliferation, yet its physiological roles remain unclear. We have used the zebrafish as a model to analyze Kcnh1 function in vitro and in vivo. We found that the kcnh1 gene is duplicated in teleost fish (i.e. kcnh1a and kcnh1b) and that both genes are maternally expressed during early development. In adult zebrafish, kcnh1a and kcnh1b have distinct expression patterns but share expression in brain and testis. Heterologous expression of both genes in Xenopus oocytes revealed a strong conservation of characteristic functional properties between human and fish channels, including a unique sensitivity to intracellular Ca2+/calmodulin and modulation of voltage-dependent gating by extracellular Mg2+. Using a morpholino antisense approach, we demonstrate a strong kcnh1 loss-of-function phenotype in developing zebrafish, characterized by growth retardation, delayed hindbrain formation, and embryonic lethality. This late phenotype was preceded by transcriptional up-regulation of known cell-cycle inhibitors (p21, p27, cdh2) and down-regulation of pro-proliferative factors, including cyclin D1, at 70% epiboly. These results reveal an unanticipated basic activity of kcnh1 that is crucial for early embryonic development and patterning.
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Affiliation(s)
- Rayk Stengel
- Friedrich Schiller University of Jena and Jena University Hospital, Center for Molecular Biomedicine, Department of Biophysics
| | - Eric Rivera-Milla
- Leibniz Institute for Age Research-Fritz Lipmann Institute, D-07745 Jena, Germany
| | - Nirakar Sahoo
- Friedrich Schiller University of Jena and Jena University Hospital, Center for Molecular Biomedicine, Department of Biophysics
| | - Christina Ebert
- Leibniz Institute for Age Research-Fritz Lipmann Institute, D-07745 Jena, Germany
| | - Frank Bollig
- Leibniz Institute for Age Research-Fritz Lipmann Institute, D-07745 Jena, Germany
| | - Stefan H Heinemann
- Friedrich Schiller University of Jena and Jena University Hospital, Center for Molecular Biomedicine, Department of Biophysics
| | - Roland Schönherr
- Friedrich Schiller University of Jena and Jena University Hospital, Center for Molecular Biomedicine, Department of Biophysics.
| | - Christoph Englert
- Leibniz Institute for Age Research-Fritz Lipmann Institute, D-07745 Jena, Germany
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Towards therapeutic applications of arthropod venom k(+)-channel blockers in CNS neurologic diseases involving memory acquisition and storage. J Toxicol 2012; 2012:756358. [PMID: 22701481 PMCID: PMC3373146 DOI: 10.1155/2012/756358] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2011] [Accepted: 02/08/2012] [Indexed: 12/31/2022] Open
Abstract
Potassium channels are the most heterogeneous and widely distributed group of ion channels and play important functions in all cells, in both normal and pathological mechanisms, including learning and memory processes. Being fundamental for many diverse physiological processes, K+-channels are recognized as potential therapeutic targets in the treatment of several Central Nervous System (CNS) diseases, such as multiple sclerosis, Parkinson's and Alzheimer's diseases, schizophrenia, HIV-1-associated dementia, and epilepsy. Blockers of these channels are therefore potential candidates for the symptomatic treatment of these neuropathies, through their neurological effects. Venomous animals have evolved a wide set of toxins for prey capture and defense. These compounds, mainly peptides, act on various pharmacological targets, making them an innumerable source of ligands for answering experimental paradigms, as well as for therapeutic application. This paper provides an overview of CNS K+-channels involved in memory acquisition and storage and aims at evaluating the use of highly selective K+-channel blockers derived from arthropod venoms as potential therapeutic agents for CNS diseases involving learning and memory mechanisms.
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Ferreira NR, Mitkovski M, Stühmer W, Pardo LA, Del Bel EA. Ether-à-go-go 1 (Eag1) Potassium Channel Expression in Dopaminergic Neurons of Basal Ganglia is Modulated by 6-Hydroxydopamine Lesion. Neurotox Res 2011; 21:317-33. [DOI: 10.1007/s12640-011-9286-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2011] [Revised: 09/09/2011] [Accepted: 09/24/2011] [Indexed: 10/16/2022]
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de Oliveira RW, Martin S, de Oliveira CL, Milani H, Schiavon A, Joca S, Pardo L, Stühmer W, Del Bel E. Eag1, Eag2, and SK3 potassium channel expression in the rat hippocampus after global transient brain ischemia. J Neurosci Res 2011; 90:632-40. [DOI: 10.1002/jnr.22772] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2011] [Revised: 07/19/2011] [Accepted: 07/28/2011] [Indexed: 11/08/2022]
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Kohl T, Lörinczi E, Pardo LA, Stühmer W. Rapid internalization of the oncogenic K+ channel K(V)10.1. PLoS One 2011; 6:e26329. [PMID: 22022602 PMCID: PMC3192180 DOI: 10.1371/journal.pone.0026329] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2011] [Accepted: 09/24/2011] [Indexed: 11/18/2022] Open
Abstract
K(V)10.1 is a mammalian brain voltage-gated potassium channel whose ectopic expression outside of the brain has been proven relevant for tumor biology. Promotion of cancer cell proliferation by K(V)10.1 depends largely on ion flow, but some oncogenic properties remain in the absence of ion permeation. Additionally, K(V)10.1 surface populations are small compared to large intracellular pools. Control of protein turnover within cells is key to both cellular plasticity and homeostasis, and therefore we set out to analyze how endocytic trafficking participates in controlling K(V)10.1 intracellular distribution and life cycle. To follow plasma membrane K(V)10.1 selectively, we generated a modified channel of displaying an extracellular affinity tag for surface labeling by α-bungarotoxin. This modification only minimally affected K(V)10.1 electrophysiological properties. Using a combination of microscopy and biochemistry techniques, we show that K(V)10.1 is constitutively internalized involving at least two distinct pathways of endocytosis and mainly sorted to lysosomes. This occurs at a relatively fast rate. Simultaneously, recycling seems to contribute to maintain basal K(V)10.1 surface levels. Brief K(V)10.1 surface half-life and rapid lysosomal targeting is a relevant factor to be taken into account for potential drug delivery and targeting strategies directed against K(V)10.1 on tumor cells.
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Affiliation(s)
- Tobias Kohl
- Max-Planck-Institute of Experimental Medicine, Department of Molecular Biology of Neuronal Signals, Göttingen, Germany
| | - Eva Lörinczi
- Max-Planck-Institute of Experimental Medicine, Department of Molecular Biology of Neuronal Signals, Göttingen, Germany
| | - Luis A. Pardo
- Max-Planck-Institute of Experimental Medicine, Department of Molecular Biology of Neuronal Signals, Göttingen, Germany
| | - Walter Stühmer
- Max-Planck-Institute of Experimental Medicine, Department of Molecular Biology of Neuronal Signals, Göttingen, Germany
- DFG Research Center for Molecular Physiology of the Brain (CMPB), Göttingen, Germany
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Abstract
Ion channels are involved in a variety of tumors. In particular, potassium channels are expressed abnormally in many cancer types, where their pharmacologic manipulation impairs tumor progression. Since this group of molecules has been successfully targeted for decades in other therapeutic areas, there is a significant body of knowledge on the pharmacology of potassium channels. Several groups of potassium channels with defined molecular identities have been proposed as candidates for therapeutic intervention. The strategies put forward range from classical small molecule blockade to gene therapy approaches, and include the use of potassium channels as targets for adjuvant therapy. We will discuss the reasons for these proposals and explore possible future developments.
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Chen Y, Sánchez A, Rubio ME, Kohl T, Pardo LA, Stühmer W. Functional K(v)10.1 channels localize to the inner nuclear membrane. PLoS One 2011; 6:e19257. [PMID: 21559285 PMCID: PMC3086910 DOI: 10.1371/journal.pone.0019257] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2010] [Accepted: 03/31/2011] [Indexed: 01/09/2023] Open
Abstract
Ectopically expressed human KV10.1 channels are relevant players in tumor biology. However, their function as ion channels at the plasma membrane does not totally explain their crucial role in tumors. Both in native and heterologous systems, it has been observed that a majority of KV10.1 channels remain at intracellular locations. In this study we investigated the localization and possible roles of perinuclear KV10.1. We show that KV10.1 is expressed at the inner nuclear membrane in both human and rat models; it co-purifies with established inner nuclear membrane markers, shows resistance to detergent extraction and restricted mobility, all of them typical features of proteins at the inner nuclear membrane. KV10.1 channels at the inner nuclear membrane are not all transported directly from the ER but rather have been exposed to the extracellular milieu. Patch clamp experiments on nuclei devoid of external nuclear membrane reveal the existence of channel activity compatible with KV10.1. We hypothesize that KV10.1 channels at the nuclear envelope might participate in the homeostasis of nuclear K+, or indirectly interact with heterochromatin, both factors known to affect gene expression.
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Affiliation(s)
- Ye Chen
- Department of Molecular Biology of Neuronal Signals, Max-Planck-Institute of Experimental Medicine, Göttingen, Germany
| | - Araceli Sánchez
- Department of Molecular Biology of Neuronal Signals, Max-Planck-Institute of Experimental Medicine, Göttingen, Germany
| | - María E. Rubio
- Department of Molecular Biology of Neuronal Signals, Max-Planck-Institute of Experimental Medicine, Göttingen, Germany
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut, United States of America
| | - Tobias Kohl
- Department of Molecular Biology of Neuronal Signals, Max-Planck-Institute of Experimental Medicine, Göttingen, Germany
| | - Luis A. Pardo
- Department of Molecular Biology of Neuronal Signals, Max-Planck-Institute of Experimental Medicine, Göttingen, Germany
- * E-mail: (LAP); (WS)
| | - Walter Stühmer
- Department of Molecular Biology of Neuronal Signals, Max-Planck-Institute of Experimental Medicine, Göttingen, Germany
- * E-mail: (LAP); (WS)
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Shen Q, Zhang J, Wang Y, Liu B, Li X, Zhao Q, Chen S, Ji J, Yang F, Wan C, Gao L, Xu Y, Feng G, He L, He G. No association between the KCNH1, KCNJ10 and KCNN3 genes and schizophrenia in the Han Chinese population. Neurosci Lett 2011; 487:61-5. [PMID: 20933057 DOI: 10.1016/j.neulet.2010.09.074] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2010] [Revised: 09/15/2010] [Accepted: 09/29/2010] [Indexed: 11/30/2022]
Affiliation(s)
- Qi Shen
- Bio-X Center, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders (Ministry of Education), Shanghai Jiao Tong University, Shanghai, China
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Asher V, Sowter H, Shaw R, Bali A, Khan R. Eag and HERG potassium channels as novel therapeutic targets in cancer. World J Surg Oncol 2010; 8:113. [PMID: 21190577 PMCID: PMC3022597 DOI: 10.1186/1477-7819-8-113] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2010] [Accepted: 12/29/2010] [Indexed: 12/03/2022] Open
Abstract
Voltage gated potassium channels have been extensively studied in relation to cancer. In this review, we will focus on the role of two potassium channels, Ether à-go-go (Eag), Human ether à-go-go related gene (HERG), in cancer and their potential therapeutic utility in the treatment of cancer. Eag and HERG are expressed in cancers of various organs and have been implicated in cell cycle progression and proliferation of cancer cells. Inhibition of these channels has been shown to reduce proliferation both in vitro and vivo studies identifying potassium channel modulators as putative inhibitors of tumour progression. Eag channels in view of their restricted expression in normal tissue may emerge as novel tumour biomarkers.
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Affiliation(s)
- Viren Asher
- Department of Obstetrics and Gynaecology, School of Graduate Medicine and Health, Royal Derby Hospital, Uttoxeter road, Derby DE22 3DT, UK.
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Martin S, Lino-de-Oliveira C, Joca SRL, Weffort de Oliveira R, Echeverry MB, Da Silva CA, Pardo L, Stühmer W, Bel ED. Eag 1, Eag 2 and Kcnn3 gene brain expression of isolated reared rats. GENES BRAIN AND BEHAVIOR 2010; 9:918-24. [DOI: 10.1111/j.1601-183x.2010.00632.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Agarwal JR, Griesinger F, Stühmer W, Pardo LA. The potassium channel Ether à go-go is a novel prognostic factor with functional relevance in acute myeloid leukemia. Mol Cancer 2010; 9:18. [PMID: 20105281 PMCID: PMC2835655 DOI: 10.1186/1476-4598-9-18] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2009] [Accepted: 01/27/2010] [Indexed: 11/16/2022] Open
Abstract
Background The voltage-gated potassium channel hEag1 (KV10.1) has been related to cancer biology. The physiological expression of the human channel is restricted to the brain but it is frequently and abundantly expressed in many solid tumors, thereby making it a promising target for a specific diagnosis and therapy. Because chronic lymphatic leukemia has been described not to express hEag1, it has been assumed that the channel is not expressed in hematopoietic neoplasms in general. Results Here we show that this assumption is not correct, because the channel is up-regulated in myelodysplastic syndromes, chronic myeloid leukemia and almost half of the tested acute myeloid leukemias in a subtype-dependent fashion. Most interestingly, channel expression strongly correlated with increasing age, higher relapse rates and a significantly shorter overall survival. Multivariate Cox regression analysis revealed hEag1 expression levels in AML as an independent predictive factor for reduced disease-free and overall survival; such an association had not been reported before. As a functional correlate, specific hEag1 blockade inhibited the proliferation and migration of several AML cell lines and primary cultured AML cells in vitro. Conclusion Our observations implicate hEag1 as novel target for diagnostic, prognostic and/or therapeutic approaches in AML.
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Affiliation(s)
- Jasmin R Agarwal
- Max-Planck-Institute of Experimental Medicine, Hermann-Rein-Str, 3, 37075 Göttingen, Germany
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Abstract
The human genome encodes 40 voltage-gated K(+) channels (K(V)), which are involved in diverse physiological processes ranging from repolarization of neuronal and cardiac action potentials, to regulating Ca(2+) signalling and cell volume, to driving cellular proliferation and migration. K(V) channels offer tremendous opportunities for the development of new drugs to treat cancer, autoimmune diseases and metabolic, neurological and cardiovascular disorders. This Review discusses pharmacological strategies for targeting K(V) channels with venom peptides, antibodies and small molecules, and highlights recent progress in the preclinical and clinical development of drugs targeting the K(V)1 subfamily, the K(V)7 subfamily (also known as KCNQ), K(V)10.1 (also known as EAG1 and KCNH1) and K(V)11.1 (also known as HERG and KCNH2) channels.
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