1
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Tan WLA, Hudson NJ, Porto Neto LR, Reverter A, Afonso J, Fortes MRS. An association weight matrix identified biological pathways associated with bull fertility traits in a multi-breed population. Anim Genet 2024. [PMID: 38692842 DOI: 10.1111/age.13431] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Revised: 02/26/2024] [Accepted: 04/01/2024] [Indexed: 05/03/2024]
Abstract
Using seven indicator traits, we investigated the genetic basis of bull fertility and predicted gene interactions from SNP associations. We used percent normal sperm as the key phenotype for the association weight matrix-partial correlation information theory (AWM-PCIT) approach. Beyond a simple list of candidate genes, AWM-PCIT predicts significant gene interactions and associations for the selected traits. These interactions formed a network of 537 genes: 38 genes were transcription cofactors, and 41 genes were transcription factors. The network displayed two distinct clusters, one with 294 genes and another with 243 genes. The network is enriched in fertility-associated pathways: steroid biosynthesis, p53 signalling, and the pentose phosphate pathway. Enrichment analysis also highlighted gene ontology terms associated with 'regulation of neurotransmitter secretion' and 'chromatin formation'. Our network recapitulates some genes previously implicated in another network built with lower-density genotypes. Sequence-level data also highlights additional candidate genes relevant to bull fertility, such as FOXO4, FOXP3, GATA1, CYP27B1, and EBP. A trio of regulatory genes-KDM5C, LRRK2, and PME-was deemed core to the network because of their overarching connections. This trio probably influences bull fertility through their interaction with genes, both known and unknown as to their role in male fertility. Future studies may target the trio and their target genes to enrich our understanding of male fertility further.
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Affiliation(s)
- Wei Liang Andre Tan
- School of Chemistry and Molecular Bioscience, The University of Queensland, St Lucia, Queensland, Australia
| | - Nicholas James Hudson
- School of Agriculture and Food Sustainability, The University of Queensland, Gatton, Queensland, Australia
| | | | | | - Juliano Afonso
- School of Chemistry and Molecular Bioscience, The University of Queensland, St Lucia, Queensland, Australia
- Empresa Brasileira de Pesquisa Agropecuária, Pecuária Sudeste, São Carlos, São Paulo, Brazil
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2
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Aufy M, Hussein AM, Stojanovic T, Studenik CR, Kotob MH. Proteolytic Activation of the Epithelial Sodium Channel (ENaC): Its Mechanisms and Implications. Int J Mol Sci 2023; 24:17563. [PMID: 38139392 PMCID: PMC10743461 DOI: 10.3390/ijms242417563] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Revised: 12/10/2023] [Accepted: 12/14/2023] [Indexed: 12/24/2023] Open
Abstract
Epithelial sodium channel (ENaC) are integral to maintaining salt and water homeostasis in various biological tissues, including the kidney, lung, and colon. They enable the selective reabsorption of sodium ions, which is a process critical for controlling blood pressure, electrolyte balance, and overall fluid volume. ENaC activity is finely controlled through proteolytic activation, a process wherein specific enzymes, or proteases, cleave ENaC subunits, resulting in channel activation and increased sodium reabsorption. This regulatory mechanism plays a pivotal role in adapting sodium transport to different physiological conditions. In this review article, we provide an in-depth exploration of the role of proteolytic activation in regulating ENaC activity. We elucidate the involvement of various proteases, including furin-like convertases, cysteine, and serine proteases, and detail the precise cleavage sites and regulatory mechanisms underlying ENaC activation by these proteases. We also discuss the physiological implications of proteolytic ENaC activation, focusing on its involvement in blood pressure regulation, pulmonary function, and intestinal sodium absorption. Understanding the mechanisms and consequences of ENaC proteolytic activation provides valuable insights into the pathophysiology of various diseases, including hypertension, pulmonary disorders, and various gastrointestinal conditions. Moreover, we discuss the potential therapeutic avenues that emerge from understanding these mechanisms, offering new possibilities for managing diseases associated with ENaC dysfunction. In summary, this review provides a comprehensive discussion of the intricate interplay between proteases and ENaC, emphasizing the significance of proteolytic activation in maintaining sodium and fluid balance in both health and disease.
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Affiliation(s)
- Mohammed Aufy
- Division of Pharmacology and Toxicology, Department of Pharmaceutical Sciences, University of Vienna, 1090 Vienna, Austria; (A.M.H.); (M.H.K.)
| | - Ahmed M. Hussein
- Division of Pharmacology and Toxicology, Department of Pharmaceutical Sciences, University of Vienna, 1090 Vienna, Austria; (A.M.H.); (M.H.K.)
- Department of Zoology, Faculty of Science, Al-Azhar University, Assiut 71524, Egypt
| | - Tamara Stojanovic
- Programme for Proteomics, Paracelsus Medical University, 5020 Salzburg, Austria;
| | - Christian R. Studenik
- Division of Pharmacology and Toxicology, Department of Pharmaceutical Sciences, University of Vienna, 1090 Vienna, Austria; (A.M.H.); (M.H.K.)
| | - Mohamed H. Kotob
- Division of Pharmacology and Toxicology, Department of Pharmaceutical Sciences, University of Vienna, 1090 Vienna, Austria; (A.M.H.); (M.H.K.)
- Department of Pathology, Faculty of Veterinary Medicine, Assiut University, Assiut 71515, Egypt
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3
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Petratou D, Gjikolaj M, Kaulich E, Schafer W, Tavernarakis N. A proton-inhibited DEG/ENaC ion channel maintains neuronal ionstasis and promotes neuronal survival under stress. iScience 2023; 26:107117. [PMID: 37416472 PMCID: PMC10320524 DOI: 10.1016/j.isci.2023.107117] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Revised: 03/28/2023] [Accepted: 06/09/2023] [Indexed: 07/08/2023] Open
Abstract
The nervous system participates in the initiation and modulation of systemic stress. Ionstasis is of utmost importance for neuronal function. Imbalance in neuronal sodium homeostasis is associated with pathologies of the nervous system. However, the effects of stress on neuronal Na+ homeostasis, excitability, and survival remain unclear. We report that the DEG/ENaC family member DEL-4 assembles into a proton-inactivated sodium channel. DEL-4 operates at the neuronal membrane and synapse to modulate Caenorhabditis elegans locomotion. Heat stress and starvation alter DEL-4 expression, which in turn alters the expression and activity of key stress-response transcription factors and triggers appropriate motor adaptations. Similar to heat stress and starvation, DEL-4 deficiency causes hyperpolarization of dopaminergic neurons and affects neurotransmission. Using humanized models of neurodegenerative diseases in C. elegans, we showed that DEL-4 promotes neuronal survival. Our findings provide insights into the molecular mechanisms by which sodium channels promote neuronal function and adaptation under stress.
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Affiliation(s)
- Dionysia Petratou
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology, Heraklion, 70013 Crete, Greece
- Department of Basic Sciences, Medical School, University of Crete, Heraklion, 71003 Crete, Greece
| | - Martha Gjikolaj
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology, Heraklion, 70013 Crete, Greece
- Department of Basic Sciences, Medical School, University of Crete, Heraklion, 71003 Crete, Greece
| | - Eva Kaulich
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, CB2 0QH Cambridge, UK
| | - William Schafer
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, CB2 0QH Cambridge, UK
| | - Nektarios Tavernarakis
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology, Heraklion, 70013 Crete, Greece
- Department of Basic Sciences, Medical School, University of Crete, Heraklion, 71003 Crete, Greece
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4
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Deng W, He J, Tang XM, Li CY, Tong J, Qi D, Wang DX. Alcohol inhibits alveolar fluid clearance through the epithelial sodium channel via the A2 adenosine receptor in acute lung injury. Mol Med Rep 2021; 24:725. [PMID: 34396442 PMCID: PMC8404097 DOI: 10.3892/mmr.2021.12364] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Accepted: 07/26/2021] [Indexed: 12/16/2022] Open
Abstract
Chronic alcohol abuse increases the risk of mortality and poor outcomes in patients with acute respiratory distress syndrome. However, the underlying mechanisms remain to be elucidated. The present study aimed to investigate the effects of chronic alcohol consumption on lung injury and clarify the signaling pathways involved in the inhibition of alveolar fluid clearance (AFC). In order to produce rodent models with chronic alcohol consumption, wild‑type C57BL/6 mice were treated with alcohol. A2a adenosine receptor (AR) small interfering (si)RNA or A2bAR siRNA were transfected into the lung tissue of mice and primary rat alveolar type II (ATII) cells. The rate of AFC in lung tissue was measured during exposure to lipopolysaccharide (LPS). Epithelial sodium channel (ENaC) expression was determined to investigate the mechanisms underlying alcohol‑induced regulation of AFC. In the present study, exposure to alcohol reduced AFC, exacerbated pulmonary edema and worsened LPS‑induced lung injury. Alcohol caused a decrease in cyclic adenosine monophosphate (cAMP) levels and inhibited α‑ENaC, β‑ENaC and γ‑ENaC expression levels in the lung tissue of mice and ATII cells. Furthermore, alcohol decreased α‑ENaC, β‑ENaC and γ‑ENaC expression levels via the A2aAR or A2bAR‑cAMP signaling pathways in vitro. In conclusion, the results of the present study demonstrated that chronic alcohol consumption worsened lung injury by aggravating pulmonary edema and impairing AFC. An alcohol‑induced decrease of α‑ENaC, β‑ENaC and γ‑ENaC expression levels by the A2AR‑mediated cAMP pathway may be responsible for the exacerbated effects of chronic alcohol consumption in lung injury.
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Affiliation(s)
- Wang Deng
- Department of Respiratory and Critical Care Medicine, Second Affiliated Hospital of Chongqing Medical University, Chongqing 400010, P.R. China
| | - Jing He
- Department of Respiratory and Critical Care Medicine, Second Affiliated Hospital of Chongqing Medical University, Chongqing 400010, P.R. China
| | - Xu-Mao Tang
- Department of Respiratory and Critical Care Medicine, Second Affiliated Hospital of Chongqing Medical University, Chongqing 400010, P.R. China
| | - Chang-Yi Li
- Department of Respiratory and Critical Care Medicine, Second Affiliated Hospital of Chongqing Medical University, Chongqing 400010, P.R. China
| | - Jin Tong
- Department of Respiratory and Critical Care Medicine, Second Affiliated Hospital of Chongqing Medical University, Chongqing 400010, P.R. China
| | - Di Qi
- Department of Respiratory and Critical Care Medicine, Second Affiliated Hospital of Chongqing Medical University, Chongqing 400010, P.R. China
| | - Dao-Xin Wang
- Department of Respiratory and Critical Care Medicine, Second Affiliated Hospital of Chongqing Medical University, Chongqing 400010, P.R. China
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5
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Goeckeler-Fried JL, Aldrin Denny R, Joshi D, Hill C, Larsen MB, Chiang AN, Frizzell RA, Wipf P, Sorscher EJ, Brodsky JL. Improved correction of F508del-CFTR biogenesis with a folding facilitator and an inhibitor of protein ubiquitination. Bioorg Med Chem Lett 2021; 48:128243. [PMID: 34246753 DOI: 10.1016/j.bmcl.2021.128243] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 06/16/2021] [Accepted: 06/30/2021] [Indexed: 11/25/2022]
Abstract
A growing number of diseases are linked to the misfolding of integral membrane proteins, and many of these proteins are targeted for ubiquitin-proteasome-dependent degradation. One such substrate is a mutant form of the Cystic Fibrosis Transmembrane Conductance Regulator (F508del-CFTR). Protein folding "correctors" that repair the F508del-CFTR folding defect have entered the clinic, but they are unlikely to protect the entire protein from degradation. To increase the pool of F508del-CFTR protein that is available for correction by existing treatments, we determined a structure-activity relationship to improve the efficacy and reduce the toxicity of an inhibitor of the E1 ubiquitin activating enzyme that facilitates F508del-CFTR maturation. A resulting lead compound lacked measurable toxicity and improved the ability of an FDA-approved corrector to augment F508del-CFTR folding, transport the protein to the plasma membrane, and maintain its activity. These data support a proof-of-concept that modest inhibition of substrate ubiquitination improves the activity of small molecule correctors to treat CF and potentially other protein conformational disorders.
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Affiliation(s)
| | - Rajiah Aldrin Denny
- Department of Inflammation & Immunology, Pfizer Inc., Cambridge, MA 02139, USA
| | - Disha Joshi
- Department of Pediatrics, Emory University School of Medicine, Atlanta, GA 30322 USA
| | - Clare Hill
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Mads B Larsen
- Department of Pediatrics, UPMC Children's Hospital of Pittsburgh, Pittsburgh, PA 15224, USA
| | - Annette N Chiang
- Department of Biological Science, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Raymond A Frizzell
- Department of Pediatrics, UPMC Children's Hospital of Pittsburgh, Pittsburgh, PA 15224, USA
| | - Peter Wipf
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Eric J Sorscher
- Department of Pediatrics, Emory University School of Medicine, Atlanta, GA 30322 USA
| | - Jeffrey L Brodsky
- Department of Biological Science, University of Pittsburgh, Pittsburgh, PA 15260, USA.
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6
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Kong L, Huang H, Luan S, Liu H, Ye M, Wu F. Inhibition of ASIC1a-Mediated ERS Improves the Activation of HSCs and Copper Transport Under Copper Load. Front Pharmacol 2021; 12:653272. [PMID: 34135753 PMCID: PMC8201774 DOI: 10.3389/fphar.2021.653272] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Accepted: 05/17/2021] [Indexed: 12/21/2022] Open
Abstract
Hepatolenticular degeneration (HLD) is an autosomal recessive genetic disease caused by the toxic accumulation of copper in the liver. Excessive copper will disrupt the redox balance in cells and tissues, causing ischemia, hypoxia, and inflammation. Acid-sensitive ion channel 1a is a cationic channel activated by extracellular acid and allowing Ca2+ and Na+ to flow into cells. Its expression appears in inflammation, arthritis, fibrotic tissue, and damaged environment, but its role in hepatolenticular degeneration has not been studied. This study established a Wistar rat model of high copper accumulation and used CuSO4 to induce the activation of HSC-T6 in an in vitro experiment. In vivo, Wistar rats were examined to determine the serum copper concentration, serum ALT and AST activities, and liver copper accumulation, and liver tissue HE staining and immunohistochemical analyses were conducted. The expression of ASIC1a, α-SMA, Collagen-Ι, GRP78, XBP1, ATP7B, and CCS were detected. Besides, immunofluorescence technology can detect the expression of the phosphorylated protein in vitro. It is suggested that ASIC1a is involved in the quality control of the endoplasmic reticulum, which degrades mutant ATP7B and increases the accumulation of copper. After blocking or silencing the expression of ASIC1a, ELISA can detect the level of inflammatory factors, the expression of endoplasmic reticulum stress-related factors, and ATP7B was improved in a higher copper environment reduction of copper deposition was observed in liver Timm’s staining. Collectively, we conclude that ASIC1a is involved in the HSC activation induced by copper accumulation and promotes the occurrence of hepatolenticular fibrosis.
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Affiliation(s)
- Lingjin Kong
- Inflammation and Immune Mediated Diseases Laboratory of Anhui Province, School of Pharmacy, Anhui Institute of Innovative Drugs, Anhui Medical University, Hefei, China
| | - Huiping Huang
- Inflammation and Immune Mediated Diseases Laboratory of Anhui Province, School of Pharmacy, Anhui Institute of Innovative Drugs, Anhui Medical University, Hefei, China
| | - Shaohua Luan
- Inflammation and Immune Mediated Diseases Laboratory of Anhui Province, School of Pharmacy, Anhui Institute of Innovative Drugs, Anhui Medical University, Hefei, China
| | - Hui Liu
- Inflammation and Immune Mediated Diseases Laboratory of Anhui Province, School of Pharmacy, Anhui Institute of Innovative Drugs, Anhui Medical University, Hefei, China
| | - Manping Ye
- Inflammation and Immune Mediated Diseases Laboratory of Anhui Province, School of Pharmacy, Anhui Institute of Innovative Drugs, Anhui Medical University, Hefei, China
| | - Fanrong Wu
- Inflammation and Immune Mediated Diseases Laboratory of Anhui Province, School of Pharmacy, Anhui Institute of Innovative Drugs, Anhui Medical University, Hefei, China
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7
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Foote AG, Thibeault SL. Sensory Innervation of the Larynx and the Search for Mucosal Mechanoreceptors. JOURNAL OF SPEECH, LANGUAGE, AND HEARING RESEARCH : JSLHR 2021; 64:371-391. [PMID: 33465318 PMCID: PMC8632506 DOI: 10.1044/2020_jslhr-20-00350] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 09/19/2020] [Accepted: 10/28/2020] [Indexed: 05/03/2023]
Abstract
Purpose The larynx is a uniquely situated organ, juxtaposed between the gastrointestinal and respiratory tracts, and endures considerable immunological challenges while providing reflexogenic responses via putative mucosal mechanoreceptor afferents. Laryngeal afferents mediate precise monitoring of sensory events by relay to the internal branch of the superior laryngeal nerve (iSLN). Exposure to a variety of stimuli (e.g., mechanical, chemical, thermal) at the mucosa-airway interface has likely evolved a diverse array of specialized sensory afferents for rapid laryngeal control. Accordingly, mucosal mechanoreceptors in demarcated laryngeal territories have been hypothesized as primary sources of sensory input. The purpose of this article is to provide a tutorial on current evidence for laryngeal afferent receptors in mucosa, the role of mechano-gated ion channels within airway epithelia and mechanisms for mechanoreceptors implicated in laryngeal health and disease. Method An overview was conducted on the distribution and identity of iSLN-mediated afferent receptors in the larynx, with specific focus on mechanoreceptors and their functional roles in airway mucosa. Results/Conclusions Laryngeal somatosensation at the cell and molecular level is still largely unexplored. This tutorial consolidates various animal and human researches, with translational emphasis provided for the importance of mucosal mechanoreceptors to normal and abnormal laryngeal function. Information presented in this tutorial has relevance to both clinical and research arenas. Improved understanding of iSLN innervation and corresponding mechanotransduction events will help shed light upon a variety of pathological reflex responses, including persistent cough, dysphonia, and laryngospasm.
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Affiliation(s)
- Alexander G. Foote
- Division of Otolaryngology–Head and Neck Surgery, University of Wisconsin–Madison
| | - Susan L. Thibeault
- Division of Otolaryngology–Head and Neck Surgery, University of Wisconsin–Madison
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8
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Mambalgin-2 Induces Cell Cycle Arrest and Apoptosis in Glioma Cells via Interaction with ASIC1a. Cancers (Basel) 2020; 12:cancers12071837. [PMID: 32650495 PMCID: PMC7408772 DOI: 10.3390/cancers12071837] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 06/27/2020] [Accepted: 07/02/2020] [Indexed: 02/06/2023] Open
Abstract
Gliomas are fast growing and highly invasive brain tumors, characterized by tumor microenvironment acidification that drives glioma cell growth and migration. Channels containing Acid-sensing Ion Channel 1a subunit (ASIC1a) mediate amiloride-sensitive cation influx in late stage glioma cells, but not in normal astrocytes. Thus, selective targeting of ASIC1a can be a perspective strategy for glioma treatment. Here, ASIC1a expression in U251 MG and A172 glioma cells, but not in normal astrocytes, was demonstrated. Recombinant analog of mambalgin-2 from black mamba Dendroaspis polylepis inhibited amiloride-sensitive currents at ASIC1a both in Xenopus laevis oocytes and in U251 MG cells, while its mutants with impaired activity towards this channel did not. Mambalgin-2 inhibited U251 MG and A172 glioma cells growth with EC50 in the nanomolar range without affecting the proliferation of normal astrocytes. Notably, mambalgin-2 mutants did not affect glioma cell proliferation, pointing on ASIC1a as the main molecular target of mambalgin-2 in U251 MG and A172 cells. Mambalgin-2 induced a cell cycle arrest, inhibited Cyclin D1 and cyclin-dependent kinases (CDK) phosphorylation and caused apoptosis in U251 MG and A172 cells. Moreover, mambalgin-2 inhibited the growth of low-passage primary cells from a patient with glioblastoma. Altogether, our data point to mambalgin-2 as a useful hit for the development of new drugs for glioma treatment.
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9
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Abstract
Hypertension is still the number one global killer. No matter what causes are, lowering blood pressure can significantly reduce cardiovascular complications, cardiovascular death, and total death. Unfortunately, some hypertensive individuals simply do not know having hypertension. Some knew it but either not being treated or treated but blood pressure does not achieve goal. The reasons for inadequate control of blood pressure are many. One important reason is that we are not very familiar with antihypertensive agents and less attention has been paid to comorbidities, complications as well as the hypertension-modified target organ damage in patients with hypertension. The right antihypertensive drug was not given to the right hypertensive patients at right time. This reviewer studied comprehensively the literature, hopefully that the review will help improve antihypertensive drug selection and antihypertensive therapy.
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Affiliation(s)
- Rutai Hui
- Chinese Academy of Medical Sciences FUWAI Hospital Hypertension Division, 167 Beilishilu West City District, 100037, Beijing People's Republic of China, China.
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10
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Li Q, Fung E. Multifaceted Functions of Epithelial Na + Channel in Modulating Blood Pressure. Hypertension 2019; 73:273-281. [PMID: 30580685 DOI: 10.1161/hypertensionaha.118.12330] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Qi Li
- From the Division of Cardiology, Department of Medicine and Therapeutics, Faculty of Medicine, The Chinese University of Hong Kong (Q.L., E.F.).,Laboratory for Heart Failure and Circulation Research, Li Ka Shing Institute of Health Sciences, Prince of Wales Hospital, Hong Kong SAR (Q.L., E.F.)
| | - Erik Fung
- From the Division of Cardiology, Department of Medicine and Therapeutics, Faculty of Medicine, The Chinese University of Hong Kong (Q.L., E.F.).,Gerald Choa Cardiac Research Centre, Faculty of Medicine, The Chinese University of Hong Kong (E.F.).,Lui Che Woo Institute of Innovative Medicine, Faculty of Medicine, The Chinese University of Hong Kong (E.F.).,Laboratory for Heart Failure and Circulation Research, Li Ka Shing Institute of Health Sciences, Prince of Wales Hospital, Hong Kong SAR (Q.L., E.F.)
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11
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Elkhatib W, Smith CL, Senatore A. A Na + leak channel cloned from Trichoplax adhaerens extends extracellular pH and Ca 2+ sensing for the DEG/ENaC family close to the base of Metazoa. J Biol Chem 2019; 294:16320-16336. [PMID: 31527080 PMCID: PMC6827283 DOI: 10.1074/jbc.ra119.010542] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Revised: 09/11/2019] [Indexed: 12/22/2022] Open
Abstract
Acid-sensitive ion channels belonging to the degenerin/epithelial sodium channel (DEG/ENaC) family activate in response to extracellular protons and are considered unique to deuterostomes. However, sensitivity to pH/protons is more widespread, where, for example, human ENaC Na+ leak channels are potentiated and mouse BASIC and Caenorhabditis elegans ACD-1 Na+ leak channels are blocked by extracellular protons. For many DEG/ENaC channels, extracellular Ca2+ ions modulate gating, and in some cases, the binding of protons and Ca2+ is interdependent. Here, we functionally characterize a DEG/ENaC channel from the early-diverging animal Trichoplax adhaerens, TadNaC6, that conducts Na+-selective leak currents in vitro sensitive to blockade by both extracellular protons and Ca2+. We determine that proton block is enhanced in low external Ca2+ concentration, whereas calcium block is enhanced in low external proton concentration, indicative of competitive binding of these two ligands to extracellular sites of the channel protein. TadNaC6 lacks most determinant residues for proton and Ca2+ sensitivity in other DEG/ENaC channels, and a mutation of one conserved residue (S353A) associated with Ca2+ block in rodent BASIC channels instead affected proton sensitivity, all indicative of independent evolution of H+ and Ca2+ sensitivity. Strikingly, TadNaC6 was potently activated by the general DEG/ENaC channel blocker amiloride, a rare feature only reported for the acid-activated channel ASIC3. The sequence and structural divergence of TadNaC6, coupled with its noncanonical functional features, provide unique opportunities for probing the proton, Ca2+, and amiloride regulation of DEG/ENaC channels and insight into the possible core-gating features of ancestral ion channels.
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Affiliation(s)
- Wassim Elkhatib
- Department of Biology, University of Toronto Mississauga, Mississauga, Ontario L5L 1C6, Canada
| | - Carolyn L Smith
- NINDS, National Institutes of Health, Bethesda, Maryland 20892
| | - Adriano Senatore
- Department of Biology, University of Toronto Mississauga, Mississauga, Ontario L5L 1C6, Canada
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12
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Tsujimura T, Ueha R, Yoshihara M, Takei E, Nagoya K, Shiraishi N, Magara J, Inoue M. Involvement of the epithelial sodium channel in initiation of mechanically evoked swallows in anaesthetized rats. J Physiol 2019; 597:2949-2963. [PMID: 31032906 DOI: 10.1113/jp277895] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2019] [Accepted: 04/25/2019] [Indexed: 12/17/2022] Open
Abstract
KEY POINTS Afferents carried by the superior laryngeal nerve play a primary role in the initiation of laryngeal mechanically evoked swallows in anaesthetized rats. Amiloride and its analogues inhibit swallowing evoked by mechanical stimulation, but not swallowing evoked by chemical and electrical stimulation. The epithelial sodium channel is probably involved in the initiation of laryngeal mechanically evoked swallows. ABSTRACT The swallowing reflex plays a critical role in airway protection. Because impaired laryngeal mechanosensation is associated with food bolus aspiration, it is important to know how the laryngeal sensory system regulates swallowing initiation. This study was performed to clarify the neuronal mechanism of mechanically evoked swallows. Urethane-anaesthetized Sprague-Dawley male rats were used. A swallow was identified by activation of the suprahyoid and thyrohyoid muscles on electromyography. The swallowing threshold was measured by von Frey filament and electrical stimulation of the larynx. The number of swallows induced by upper airway distension and capsaicin application (0.03 nmol, 3 μl) to the vocal folds was counted. The effects of topical application (0.3-30 nmol, 3 μl) of the epithelial sodium channel (ENaC) blocker amiloride and its analogues (benzamil and dimethylamiloride), acid-sensing ion channel (ASIC) inhibitors (mambalgine-1 and diminazene) and gadolinium to the laryngeal mucosa on swallowing initiation were evaluated. A nerve transection study indicated that afferents carried by the superior laryngeal nerve play a primary role in the initiation of laryngeal mechanically evoked swallows. The mechanical threshold of swallowing was increased in a dose-dependent manner by amiloride and its analogues and gadolinium, but not by ASIC inhibitors. The number of swallows by upper airway distension was significantly decreased by benzamil application. However, the initiation of swallows evoked by capsaicin and electrical stimulation was not affected by benzamil application. We speculate that the ENaC is involved in the initiation of laryngeal mechanically evoked swallows.
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Affiliation(s)
- Takanori Tsujimura
- Division of Dysphagia Rehabilitation, Niigata University Graduate School of Medical and Dental Sciences, 2-5274 Gakkocho-dori, Chuo-ku, Niigata, 951-8514, Japan
| | - Rumi Ueha
- Department of Otolaryngology, University of Tokyo, Tokyo, 113-8655, Japan
| | - Midori Yoshihara
- Division of Dysphagia Rehabilitation, Niigata University Graduate School of Medical and Dental Sciences, 2-5274 Gakkocho-dori, Chuo-ku, Niigata, 951-8514, Japan
| | - Eri Takei
- Division of Dysphagia Rehabilitation, Niigata University Graduate School of Medical and Dental Sciences, 2-5274 Gakkocho-dori, Chuo-ku, Niigata, 951-8514, Japan
| | - Kouta Nagoya
- Division of Dysphagia Rehabilitation, Niigata University Graduate School of Medical and Dental Sciences, 2-5274 Gakkocho-dori, Chuo-ku, Niigata, 951-8514, Japan
| | - Naru Shiraishi
- Division of Dysphagia Rehabilitation, Niigata University Graduate School of Medical and Dental Sciences, 2-5274 Gakkocho-dori, Chuo-ku, Niigata, 951-8514, Japan
| | - Jin Magara
- Division of Dysphagia Rehabilitation, Niigata University Graduate School of Medical and Dental Sciences, 2-5274 Gakkocho-dori, Chuo-ku, Niigata, 951-8514, Japan
| | - Makoto Inoue
- Division of Dysphagia Rehabilitation, Niigata University Graduate School of Medical and Dental Sciences, 2-5274 Gakkocho-dori, Chuo-ku, Niigata, 951-8514, Japan
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13
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Bencheva LI, De Matteo M, Ferrante L, Ferrara M, Prandi A, Randazzo P, Ronzoni S, Sinisi R, Seneci P, Summa V, Gallo M, Veneziano M, Cellucci A, Mazzocchi N, Menegon A, Di Fabio R. Identification of Isoform 2 Acid-Sensing Ion Channel Inhibitors as Tool Compounds for Target Validation Studies in CNS. ACS Med Chem Lett 2019; 10:627-632. [PMID: 30996808 DOI: 10.1021/acsmedchemlett.8b00591] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Accepted: 02/07/2019] [Indexed: 01/21/2023] Open
Abstract
Acid-sensing ion channels (ASICs) are a family of ion channels permeable to cations and largely responsible for the onset of acid-evoked ion currents both in neurons and in different types of cancer cells, thus representing a potential target for drug discovery. Owing to the limited attention ASIC2 has received so far, an exploratory program was initiated to identify ASIC2 inhibitors using diminazene, a known pan-ASIC inhibitor, as a chemical starting point for structural elaboration. The performed exploration enabled the identification of a novel series of ASIC2 inhibitors. In particular, compound 2u is a brain penetrant ASIC2 inhibitor endowed with an optimal pharmacokinetic profile. This compound may represent a useful tool to validate in animal models in vivo the role of ASIC2 in different neurodegenerative central nervous system pathologies.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Pierfausto Seneci
- Promidis, Via Olgettina 60, 20132 Milan, Italy
- Chemistry Department, Università degli Studi di Milano, Via Golgi 19, I-20133 Milan, Italy
| | - Vincenzo Summa
- IRBM Science Park, Via Pontina Km 30.600, 00070 Pomezia, Rome, Italy
| | - Mariana Gallo
- IRBM Science Park, Via Pontina Km 30.600, 00070 Pomezia, Rome, Italy
| | - Maria Veneziano
- IRBM Science Park, Via Pontina Km 30.600, 00070 Pomezia, Rome, Italy
| | | | - Nausicaa Mazzocchi
- San Raffaele Scientific Institute, Experimental Imaging Center, ALEMBIC, Advanced Light and Electron Microscopy BioImaging Center, Via Olgettina 60, 20132 Milan, Italy
| | - Andrea Menegon
- San Raffaele Scientific Institute, Experimental Imaging Center, ALEMBIC, Advanced Light and Electron Microscopy BioImaging Center, Via Olgettina 60, 20132 Milan, Italy
| | - Romano Di Fabio
- Promidis, Via Olgettina 60, 20132 Milan, Italy
- IRBM Science Park, Via Pontina Km 30.600, 00070 Pomezia, Rome, Italy
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14
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Membrane potential changes occurring upon acidification influence the binding of small-molecule inhibitors to ASIC1a. Neuropharmacology 2019; 148:366-376. [DOI: 10.1016/j.neuropharm.2019.01.033] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Revised: 01/10/2019] [Accepted: 01/31/2019] [Indexed: 12/23/2022]
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15
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Lu K, Chen X, Zhu W, Mao X, Yang Y, Qiu J, Zhang M, Cheng R. Terbutaline alleviates the lung injury in the neonatal rats exposed to endotoxin: Potential roles of epithelial sodium channels. Pediatr Pulmonol 2019; 54:280-288. [PMID: 30644180 PMCID: PMC6618278 DOI: 10.1002/ppul.24242] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Accepted: 12/15/2018] [Indexed: 12/18/2022]
Abstract
Intrauterine inflammation generates inflammatory mediators that damage the developing bronchoalveolar epithelium, resulting in neonatal lung injury. Lung fluid transport disorders are the main reasons for the development of pulmonary edema, an important pathology of lung injury. Previous studies suggested that epithelial sodium channels (ENaCs) play an important role in lung fluid transport. Here, we investigated whether changes in the expression of ENaCs were observed when neonatal rat lung injury was induced by maternal exposure to endotoxin. We also examined the therapeutic effect of terbutaline nebulizer inhalation on this injury. The results showed that maternal exposure to endotoxin increased the levels of TNF-α and IL-1β in bronchoalveolar lavage fluid, suppressed α-, β-, γ-ENaC in the neonatal rat lung, and resulted in the formation of pulmonary edema on postnatal days 1 and 7. Terbutaline up-regulated the expression of β- and γ-ENaC in the distal lung after 7 days of treatment. The potential signal molecules cAMP, PKA, and CREB expressions were increased after terbutaline treatment. In summary, maternal exposure to endotoxin decreased the expression of ENaCs in neonatal rats which, in turn, may exacerbate pulmonary edema. Inhalation of the β2-adrenergic receptor agonist terbutaline improved lung liquid clearance. By increasing the expression of sodium ion channels, the effective removal of alveolar fluid provides a new way for the prevention and treatment of neonatal lung injury.
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Affiliation(s)
- Keyu Lu
- Department of neonates, Children's Hospital of Nanjing Medical University, Nanjing, China
| | - Xu Chen
- Department of neonates, Children's Hospital of Nanjing Medical University, Nanjing, China
| | - Weiwei Zhu
- Department of neonates, Children's Hospital of Nanjing Medical University, Nanjing, China
| | - Xiaonan Mao
- Department of neonates, Children's Hospital of Nanjing Medical University, Nanjing, China
| | - Yang Yang
- Department of neonates, Children's Hospital of Nanjing Medical University, Nanjing, China
| | - Jie Qiu
- Department of neonates, Children's Hospital of Nanjing Medical University, Nanjing, China
| | - Mingshun Zhang
- Key Laboratory of Antibody Technique of Ministry of Health, Nanjing Medical University, Nanjing, China.,Department of Immunology, Nanjing Medical University, Nanjing, China
| | - Rui Cheng
- Department of neonates, Children's Hospital of Nanjing Medical University, Nanjing, China
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16
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Maatuf Y, Geron M, Priel A. The Role of Toxins in the Pursuit for Novel Analgesics. Toxins (Basel) 2019; 11:toxins11020131. [PMID: 30813430 PMCID: PMC6409898 DOI: 10.3390/toxins11020131] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Revised: 02/17/2019] [Accepted: 02/20/2019] [Indexed: 12/19/2022] Open
Abstract
Chronic pain is a major medical issue which reduces the quality of life of millions and inflicts a significant burden on health authorities worldwide. Currently, management of chronic pain includes first-line pharmacological therapies that are inadequately effective, as in just a portion of patients pain relief is obtained. Furthermore, most analgesics in use produce severe or intolerable adverse effects that impose dose restrictions and reduce compliance. As the majority of analgesic agents act on the central nervous system (CNS), it is possible that blocking pain at its source by targeting nociceptors would prove more efficient with minimal CNS-related side effects. The development of such analgesics requires the identification of appropriate molecular targets and thorough understanding of their structural and functional features. To this end, plant and animal toxins can be employed as they affect ion channels with high potency and selectivity. Moreover, elucidation of the toxin-bound ion channel structure could generate pharmacophores for rational drug design while favorable safety and analgesic profiles could highlight toxins as leads or even as valuable therapeutic compounds themselves. Here, we discuss the use of plant and animal toxins in the characterization of peripherally expressed ion channels which are implicated in pain.
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Affiliation(s)
- Yossi Maatuf
- The Institute for Drug Research (IDR), School of Pharmacy, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem 9112001, Israel.
| | - Matan Geron
- The Institute for Drug Research (IDR), School of Pharmacy, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem 9112001, Israel.
| | - Avi Priel
- The Institute for Drug Research (IDR), School of Pharmacy, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem 9112001, Israel.
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17
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Shei RJ, Peabody JE, Kaza N, Rowe SM. The epithelial sodium channel (ENaC) as a therapeutic target for cystic fibrosis. Curr Opin Pharmacol 2018; 43:152-165. [PMID: 30340955 PMCID: PMC6294660 DOI: 10.1016/j.coph.2018.09.007] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Accepted: 09/11/2018] [Indexed: 01/28/2023]
Abstract
Cystic fibrosis (CF) is a monogenic disease caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. CFTR dysfunction is characterized by abnormal mucociliary transport due to a dehydrated airway surface liquid (ASL) and hyperviscous mucus, among other pathologies of host defense. ASL depletion is caused by the absence of CFTR mediated chloride secretion along with continued activity of the epithelial sodium channel (ENaC) activity, which can also be affected by CFTR mediated anion conductance. Therefore, ENaC has been proposed as a therapeutic target to ameliorate ASL dehydration and improve mucus transport. Inhibition of ENaC has been shown to restore ASL hydration and enhance mucociliary transport in induced models of CF lung disease. To date, no therapy inhibiting ENaC has successfully translated to clinical efficacy, in part due to concerns regarding off-target effects, systemic exposure, durability of effect, and adverse effects. Recent efforts have been made to develop novel, rationally designed therapeutics to produce-specific, long-lasting inhibition of ENaC activity in the airways while simultaneously minimizing off target fluid transport effects, systemic exposure and side effects. Such approaches comprise next-generation small molecule direct inhibitors, indirect channel-activating protease inhibitors, synthetic peptide analogs, and oligonucleotide-based therapies. These novel therapeutics represent an exciting step forward in the development of ENaC-directed therapies for CF.
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Affiliation(s)
- Ren-Jay Shei
- Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, USA; The Gregory Fleming James Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Jacelyn E Peabody
- Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, USA; Medical Scientist (MD/PhD) Training Program, University of Alabama at Birmingham, Birmingham, AL, USA; The Gregory Fleming James Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Niroop Kaza
- Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, USA; The Gregory Fleming James Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Steven M Rowe
- Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, USA; Department of Pediatrics, University of Alabama at Birmingham, Birmingham, AL, USA; Department of Cell Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, USA; The Gregory Fleming James Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, AL, USA.
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18
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Dragos D, Gilca M. Taste of phytocompounds: A better predictor for ethnopharmacological activities of medicinal plants than the phytochemical class? JOURNAL OF ETHNOPHARMACOLOGY 2018; 220:129-146. [PMID: 29604378 DOI: 10.1016/j.jep.2018.03.034] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Revised: 03/26/2018] [Accepted: 03/26/2018] [Indexed: 05/27/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE Understanding the patterns that shape traditional medical knowledge is essential for accelerating ethnopharmacological progress. According to Ayurveda, medicinal plants that belong to different taxa, but which have similar taste, may display similar (ethno)pharmacological activities (EPAs) (Bhishagratna, 1998; Sharma and Dash, 2006). AIM OF THE STUDY To understand the patterns that govern the distribution of herbal EPAs in Ayurveda and to evaluate the potential concordance between chemical class or taste of the constituent phytocompounds and EPAs. MATERIAL AND METHODS A mixed database (PhytoMolecularTasteDB) was constructed for Ayurvedic medicinal plants by integrating modern data (medicinal plant composition, phytochemical taste) with traditional data (ethnopharmacological activities of plant). PhytoMolecularTasteDB contains 431 Ayurvedic medicinal plants, 94 EPAs, 223 chemical classes of phytocompounds and 438 herbal tastants. Potential global or individual associations between chemical classes/taste of the phytoconstituents and EPAs were statistically analyzed. RESULTS There was no global statistical correlation between the various chemical classes of phytocompounds and EPAs, although there were several individual correlations. The results suggest the existence of a global statistical correlation (besides several individual correlations) between the plant "molecular taste" (various taste-based classes of phytocompounds) and EPAs. CONCLUSIONS These results suggest that phytochemical taste may be more relevant than chemical class for EPAs prediction.
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Affiliation(s)
- Dorin Dragos
- Medical Semiology Dept., Faculty of General Medicine, Carol Davila University of Medicine and Pharmacy, B-dul Eroilor Sanitari nr.8, 050471 Bucharest, Romania; Nephrology Clinic, University Emergency Hospital Bucharest, Bucharest, Romania.
| | - Marilena Gilca
- Biochemistry Dept., Faculty of General Medicine, Carol Davila University of Medicine and Pharmacy, B-dul Eroilor Sanitari nr.8, 050471 Bucharest, Romania.
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19
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Ni L, Fang P, Hu ZL, Zhou HY, Chen JG, Wang F, Jin Y. Identification and Function of Acid-sensing Ion Channels in RAW 264.7 Macrophage Cells. Curr Med Sci 2018; 38:436-442. [PMID: 30074209 DOI: 10.1007/s11596-018-1897-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Revised: 11/07/2017] [Indexed: 12/20/2022]
Abstract
Activation of acid-sensing ion channels (ASICs) plays an important role in neuroinflammation. Macrophage recruitment to the sites of inflammation is an essential step in host defense. ASIC1 and ASIC3 have been reported to mediate the endocytosis and maturation of bone marrow derived macrophages. However, the expression and inflammation-related functions of ASICs in RAW 264.7 cells, another common macrophage, are still elusive. In the present study, we first demonstrated the presence of ASIC1, ASIC2a and ASIC3 in RAW 264.7 macrophage cell line by using reverse transcriptase polymerase chain reaction (RT-PCR), Western blotting and immunofluorescence experiments. The non-specific ASICs inhibitor amiloride and specific homomeric ASICla blocker PcTxl reduced the production of iNOS and COX-2 by LPS-induced activating RAW 264.7 cells. Furthermore, not only amiloride but also PcTxl inhibited the migration and LPS-induced apoptosis of RAW 264.7 cells. Taken together, our findings suggest that ASICs promote the inflammatory response and apoptosis of RAW 264.7 cells, and ASICs may serve as a potential novel target for immunological disease therapy.
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Affiliation(s)
- Lan Ni
- Department of Pharmacology, Huazhong University of Science and Technology, Wuhan, 430030, China.,Key Laboratory of Neurological Diseases (HUST), Ministry of Education of China, Huazhong University of Science and Technology, Wuhan, 430030, China.,Key Laboratory for Drug Target Researches and Pharmacodynamic Evaluation of Hubei Province, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Peng Fang
- Department of Pharmacology, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Zhuang-Li Hu
- Department of Pharmacology, Huazhong University of Science and Technology, Wuhan, 430030, China.,Key Laboratory of Neurological Diseases (HUST), Ministry of Education of China, Huazhong University of Science and Technology, Wuhan, 430030, China.,Key Laboratory for Drug Target Researches and Pharmacodynamic Evaluation of Hubei Province, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Hai-Yun Zhou
- Department of Pharmacology, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Jian-Guo Chen
- Department of Pharmacology, Huazhong University of Science and Technology, Wuhan, 430030, China.,Key Laboratory of Neurological Diseases (HUST), Ministry of Education of China, Huazhong University of Science and Technology, Wuhan, 430030, China.,Key Laboratory for Drug Target Researches and Pharmacodynamic Evaluation of Hubei Province, Huazhong University of Science and Technology, Wuhan, 430030, China.,Institute of Brain Research, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Fang Wang
- Department of Pharmacology, Huazhong University of Science and Technology, Wuhan, 430030, China.,Key Laboratory of Neurological Diseases (HUST), Ministry of Education of China, Huazhong University of Science and Technology, Wuhan, 430030, China.,Key Laboratory for Drug Target Researches and Pharmacodynamic Evaluation of Hubei Province, Huazhong University of Science and Technology, Wuhan, 430030, China.,Institute of Brain Research, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - You Jin
- Department of Pharmacology, Huazhong University of Science and Technology, Wuhan, 430030, China. .,Key Laboratory of Neurological Diseases (HUST), Ministry of Education of China, Huazhong University of Science and Technology, Wuhan, 430030, China. .,Key Laboratory for Drug Target Researches and Pharmacodynamic Evaluation of Hubei Province, Huazhong University of Science and Technology, Wuhan, 430030, China.
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20
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Inhibition of Acid Sensing Ion Channel 3 Aggravates Seizures by Regulating NMDAR Function. Neurochem Res 2018; 43:1227-1241. [DOI: 10.1007/s11064-018-2540-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2018] [Revised: 04/23/2018] [Accepted: 04/27/2018] [Indexed: 10/17/2022]
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21
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Liu M, Inoue K, Leng T, Zhou A, Guo S, Xiong ZG. ASIC1 promotes differentiation of neuroblastoma by negatively regulating Notch signaling pathway. Oncotarget 2018; 8:8283-8293. [PMID: 28030818 PMCID: PMC5352400 DOI: 10.18632/oncotarget.14164] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Accepted: 11/23/2016] [Indexed: 12/25/2022] Open
Abstract
In neurons, up-regulation of Notch activity either inhibits neurite extension or causes retraction of neurites. Conversely, inhibition of Notch1 facilitates neurite extension. Acid-sensing ion channels (ASICs) are a family of proton-gated cation channels, which play critical roles in synaptic plasticity, learning and memory and spine morphogenesis. Our pilot proteomics data from ASIC1a knock out mice implicated that ASIC1a may play a role in regulating Notch signaling, therefore, we explored whether or not ASIC1a regulates neurite growth during neuronal development through Notch signaling. In this study, we determined the effects of ASIC1a on neurite growth in a mouse neuroblastoma cell line, NS20Y cells, by modulating ASIC1a expression. We also determined the relationship between ASIC1a and Notch signaling on neuronal differentiation. Our results showed that down-regulation of ASIC1a in NS20Y cells inhibits CPT-cAMP induced neurite growth, while over expression of ASIC1a promotes its growth. In addition, down-regulation of ASIC1a increased the expression of Notch1 and its target gene Survivin while inhibitor of Notch significantly prevented the neurite extension induced by ASIC1a in NS20Y cells. These data indicate that Notch1 signaling may be required for ASIC1a-mediated neurite growth and neuronal differentiation.
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Affiliation(s)
- Mingli Liu
- Department of Microbiology, Biochemistry & Immunology, Atlanta, GA 30310, USA
| | - Koichi Inoue
- Neuroscience Institute, Morehouse School of Medicine, Atlanta, GA 30310, USA
| | - Tiandong Leng
- Neuroscience Institute, Morehouse School of Medicine, Atlanta, GA 30310, USA
| | - An Zhou
- Neuroscience Institute, Morehouse School of Medicine, Atlanta, GA 30310, USA
| | - Shanchun Guo
- Department of Chemistry, RCMI Cancer Research Center, Xavier University of Louisiana, New Orleans, LA 70125, USA
| | - Zhi-Gang Xiong
- Neuroscience Institute, Morehouse School of Medicine, Atlanta, GA 30310, USA
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22
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Gonzales EB, Sumien N. Acidity and Acid-Sensing Ion Channels in the Normal and Alzheimer's Disease Brain. J Alzheimers Dis 2018; 57:1137-1144. [PMID: 28211811 DOI: 10.3233/jad-161131] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Alzheimer's disease prevalence has reached epidemic proportion with very few treatment options, which are associated with a multitude of side effects. A potential avenue of research for new therapies are protons, and their associated receptor: acid-sensing ion channels (ASIC). Protons are often overlooked neurotransmitters, and proton-gated currents have been identified in the brain. Furthermore, ASICs have been determined to be crucial for proper brain function. While there is more work to be done, this review is intended to highlight protons as neurotransmitters and their role along with the role of ASICs within physiological functioning of the brain. We will also cover the pathophysiological associations between ASICs and modulators of ASICs. Finally, this review will sum up how the studies of protons, ASICs and their modulators may generate new therapeutic molecules for Alzheimer's disease and other neurodegenerative diseases.
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23
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Extraoral Taste Receptor Discovery: New Light on Ayurvedic Pharmacology. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2017. [PMID: 28642799 PMCID: PMC5469997 DOI: 10.1155/2017/5435831] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
More and more research studies are revealing unexpectedly important roles of taste for health and pathogenesis of various diseases. Only recently it has been shown that taste receptors have many extraoral locations (e.g., stomach, intestines, liver, pancreas, respiratory system, heart, brain, kidney, urinary bladder, pancreas, adipose tissue, testis, and ovary), being part of a large diffuse chemosensory system. The functional implications of these taste receptors widely dispersed in various organs or tissues shed a new light on several concepts used in ayurvedic pharmacology (dravyaguna vijnana), such as taste (rasa), postdigestive effect (vipaka), qualities (guna), and energetic nature (virya). This review summarizes the significance of extraoral taste receptors and transient receptor potential (TRP) channels for ayurvedic pharmacology, as well as the biological activities of various types of phytochemical tastants from an ayurvedic perspective. The relative importance of taste (rasa), postdigestive effect (vipaka), and energetic nature (virya) as ethnopharmacological descriptors within Ayurveda boundaries will also be discussed.
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24
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Vijftigschild LAW, Berkers G, Dekkers JF, Zomer-van Ommen DD, Matthes E, Kruisselbrink E, Vonk A, Hensen CE, Heida-Michel S, Geerdink M, Janssens HM, van de Graaf EA, Bronsveld I, de Winter-de Groot KM, Majoor CJ, Heijerman HGM, de Jonge HR, Hanrahan JW, van der Ent CK, Beekman JM. β2-Adrenergic receptor agonists activate CFTR in intestinal organoids and subjects with cystic fibrosis. Eur Respir J 2016; 48:768-79. [PMID: 27471203 DOI: 10.1183/13993003.01661-2015] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Accepted: 05/11/2016] [Indexed: 01/12/2023]
Abstract
We hypothesized that people with cystic fibrosis (CF) who express CFTR (cystic fibrosis transmembrane conductance regulator) gene mutations associated with residual function may benefit from G-protein coupled receptor (GPCR)-targeting drugs that can activate and enhance CFTR function.We used intestinal organoids to screen a GPCR-modulating compound library and identified β2-adrenergic receptor agonists as the most potent inducers of CFTR function.β2-Agonist-induced organoid swelling correlated with the CFTR genotype, and could be induced in homozygous CFTR-F508del organoids and highly differentiated primary CF airway epithelial cells after rescue of CFTR trafficking by small molecules. The in vivo response to treatment with an oral or inhaled β2-agonist (salbutamol) in CF patients with residual CFTR function was evaluated in a pilot study. 10 subjects with a R117H or A455E mutation were included and showed changes in the nasal potential difference measurement after treatment with oral salbutamol, including a significant improvement of the baseline potential difference of the nasal mucosa (+6.35 mV, p<0.05), suggesting that this treatment might be effective in vivo Furthermore, plasma that was collected after oral salbutamol treatment induced CFTR activation when administered ex vivo to organoids.This proof-of-concept study suggests that organoids can be used to identify drugs that activate CFTR function in vivo and to select route of administration.
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Affiliation(s)
- Lodewijk A W Vijftigschild
- Dept of Pediatric Pulmonology, University Medical Center, Utrecht, The Netherlands Laboratory of Translational Immunology, University Medical Center, Utrecht, The Netherlands These two authors contributed equally to this work
| | - Gitte Berkers
- Dept of Pediatric Pulmonology, University Medical Center, Utrecht, The Netherlands These two authors contributed equally to this work
| | - Johanna F Dekkers
- Dept of Pediatric Pulmonology, University Medical Center, Utrecht, The Netherlands Laboratory of Translational Immunology, University Medical Center, Utrecht, The Netherlands These two authors contributed equally to this work
| | - Domenique D Zomer-van Ommen
- Dept of Pediatric Pulmonology, University Medical Center, Utrecht, The Netherlands Laboratory of Translational Immunology, University Medical Center, Utrecht, The Netherlands These two authors contributed equally to this work
| | - Elizabeth Matthes
- CF Translational Research Centre, Dept of Physiology, McGill University, Montréal, QC, Canada
| | - Evelien Kruisselbrink
- Dept of Pediatric Pulmonology, University Medical Center, Utrecht, The Netherlands Laboratory of Translational Immunology, University Medical Center, Utrecht, The Netherlands
| | - Annelotte Vonk
- Dept of Pediatric Pulmonology, University Medical Center, Utrecht, The Netherlands Laboratory of Translational Immunology, University Medical Center, Utrecht, The Netherlands
| | - Chantal E Hensen
- Dept of Pediatric Pulmonology, University Medical Center, Utrecht, The Netherlands
| | - Sabine Heida-Michel
- Dept of Pediatric Pulmonology, University Medical Center, Utrecht, The Netherlands
| | - Margot Geerdink
- Dept of Pediatric Pulmonology, University Medical Center, Utrecht, The Netherlands
| | - Hettie M Janssens
- Dept of Pediatric Pulmonology, Erasmus Medical Center/Sophia Children's Hospital, Rotterdam, The Netherlands
| | | | - Inez Bronsveld
- Dept of Pulmonology, University Medical Center, Utrecht, The Netherlands
| | | | - Christof J Majoor
- Dept of Respiratory Medicine, Academic Medical Center, Amsterdam, The Netherlands
| | - Harry G M Heijerman
- Dept of Pulmonology and Cystic Fibrosis, Haga Teaching Hospital, The Hague, The Netherlands
| | - Hugo R de Jonge
- Dept of Gastroenterology and Hepatology, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - John W Hanrahan
- CF Translational Research Centre, Dept of Physiology, McGill University, Montréal, QC, Canada
| | | | - Jeffrey M Beekman
- Dept of Pediatric Pulmonology, University Medical Center, Utrecht, The Netherlands Regenerative Medicine Center Utrecht, University Medical Center, Utrecht, The Netherlands
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25
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Xu W, Hong SJ, Zhong A, Xie P, Jia S, Xie Z, Zeitchek M, Niknam-Bienia S, Zhao J, Porterfield DM, Surmeier DJ, Leung KP, Galiano RD, Mustoe TA. Sodium channel Nax is a regulator in epithelial sodium homeostasis. Sci Transl Med 2016; 7:312ra177. [PMID: 26537257 DOI: 10.1126/scitranslmed.aad0286] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The mechanisms by which the epidermis responds to disturbances in barrier function and restores homeostasis are unknown. With a perturbation of the epidermal barrier, water is lost, resulting in an increase in extracellular sodium concentration. We demonstrate that the sodium channel Nax functions as a sodium sensor. With increased extracellular sodium, Nax up-regulates prostasin, which results in activation of the sodium channel ENaC, resulting in increased sodium flux and increased downstream mRNA synthesis of inflammatory mediators. Nax is present in multiple epithelial tissues, and up-regulation of its downstream genes is found in hypertrophic scars. In animal models, blocking Nax expression results in improvement in scarring and atopic dermatitis-like symptoms, both of which are pathological conditions characterized by perturbations in barrier function. These findings support an important role for Nax in maintaining epithelial homeostasis.
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Affiliation(s)
- Wei Xu
- Laboratory for Wound Repair and Regenerative Surgery, Department of Surgery, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Seok Jong Hong
- Laboratory for Wound Repair and Regenerative Surgery, Department of Surgery, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Aimei Zhong
- Laboratory for Wound Repair and Regenerative Surgery, Department of Surgery, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA. Department of Plastic Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430022, China
| | - Ping Xie
- Laboratory for Wound Repair and Regenerative Surgery, Department of Surgery, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Shengxian Jia
- Laboratory for Wound Repair and Regenerative Surgery, Department of Surgery, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Zhong Xie
- Department of Physiology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Michael Zeitchek
- Department of Agricultural and Biological Engineering, Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47907, USA
| | - Solmaz Niknam-Bienia
- Laboratory for Wound Repair and Regenerative Surgery, Department of Surgery, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Jingling Zhao
- Laboratory for Wound Repair and Regenerative Surgery, Department of Surgery, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA. Department of Burns, First Affiliated Hospital of Sun Yat-Sen University, Guangzhou 510080, China
| | - D Marshall Porterfield
- Department of Agricultural and Biological Engineering, Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47907, USA
| | - D James Surmeier
- Department of Physiology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Kai P Leung
- Microbiology Branch, U.S. Army Dental and Trauma Research Detachment, Institute of Surgical Research, JB Fort Sam Houston, San Antonio, TX 78234, USA
| | - Robert D Galiano
- Laboratory for Wound Repair and Regenerative Surgery, Department of Surgery, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Thomas A Mustoe
- Laboratory for Wound Repair and Regenerative Surgery, Department of Surgery, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA.
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Leng TD, Si HF, Li J, Yang T, Zhu M, Wang B, Simon RP, Xiong ZG. Amiloride Analogs as ASIC1a Inhibitors. CNS Neurosci Ther 2016; 22:468-76. [PMID: 26890278 DOI: 10.1111/cns.12524] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2015] [Revised: 12/30/2015] [Accepted: 01/16/2016] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND ASIC1a, the predominant acid-sensing ion channels (ASICs), is implicated in neurological disorders including stroke, traumatic spinal cord injury, and ALS. Potent ASIC1a inhibitors should have promising therapeutic potential for ASIC1a-related diseases. AIMS We examined the inhibitory effects of a number of amiloride analogs on ASIC1a currents, aimed at understanding the structure-activity relationship and identifying potent ASIC1a inhibitors for stroke intervention. METHODS Whole-cell patch-clamp techniques and a mouse model of middle cerebral artery occlusion (MCAO)-induced focal ischemia were used. Surflex-Dock was used to dock the analogs into the pocket with default parameters. RESULTS Amiloride and its analogs inhibit ASIC1a currents expressed in Chinese hamster ovary cells with a potency rank order of benzamil > phenamil > 5-(N,N-dimethyl)amiloride (DMA) > amiloride > 5-(N,N-hexamethylene)amiloride (HMA) ≥ 5-(N-methyl-N-isopropyl)amiloride (MIA) > 5-(N-ethyl-N-isopropyl)amiloride (EIPA). In addition, amiloride and its analogs inhibit ASIC currents in cortical neurons with the same potency rank order. In mice, benzamil and EIPA decreased MCAO-induced infarct volume. Similar to its effect on the ASIC current, benzamil showed a much higher potency than EIPA. CONCLUSION Addition of a benzyl group to the terminal guanidinyl group resulted in enhanced inhibitory activity on ASIC1a. On the other hand, the bulky groups added to the 5-amino residues slightly decreased the activity. Among the tested amiloride analogs, benzamil is the most potent ASIC1a inhibitor.
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Affiliation(s)
- Tian-Dong Leng
- Neuroscience Institute, Morehouse School of Medicine, Atlanta, GA, USA
| | - Hong-Fang Si
- Anhui Medical University, School of Pharmacy, Hefei, Anhui, China
| | - Jun Li
- Anhui Medical University, School of Pharmacy, Hefei, Anhui, China
| | - Tao Yang
- Neuroscience Institute, Morehouse School of Medicine, Atlanta, GA, USA
| | - Mengyuan Zhu
- Department of Chemistry and Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, GA, USA
| | - Binghe Wang
- Department of Chemistry and Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, GA, USA
| | - Roger P Simon
- Neuroscience Institute, Morehouse School of Medicine, Atlanta, GA, USA
| | - Zhi-Gang Xiong
- Neuroscience Institute, Morehouse School of Medicine, Atlanta, GA, USA
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Wang H, Wang YH, Yang F, Li XF, Tian YY, Ni MM, Zuo LQ, Meng XM, Huang Y. Effect of acid-sensing ion channel 1a on the process of liver fibrosis under hyperglycemia. Biochem Biophys Res Commun 2015; 468:758-65. [PMID: 26562527 DOI: 10.1016/j.bbrc.2015.11.029] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2015] [Accepted: 11/04/2015] [Indexed: 01/09/2023]
Abstract
Metabolic syndrome characterized by hyperglycemia contributes to nonalcoholic steatohepatitis-associated liver fibrosis. This study was to investigate the effects of Acid-sensing ion Channel 1a (ASIC1a) on the process of liver fibrosis under hyperglycemia. Results showed that high glucose significantly worsen the pathology of liver fibrosis in vivo. In vitro, high glucose stimulated proliferation, activation and extracellular matrix (ECM) production in HSCs, and enhanced the effect of PDGF-BB on the activation and proliferation of HSCs. These effects could be attenuated by ASIC1a specific inhibitor Psalmotoxin-1(PcTx1) or specific ShRNA for ASIC1a through Notch1/Hes-1 pathways. These data indicate that ASIC1a plays an important role in diabetes complication liver fibrosis.
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Affiliation(s)
- Huan Wang
- School of Pharmacy, Anhui Medical University, Hefei, 230032, China; Institute for Liver Diseases of Anhui Medical University (AMU), Anhui Medical University, Hefei, 230032, China.
| | - Ying-hong Wang
- School of Pharmacy, Anhui Medical University, Hefei, 230032, China; Institute for Liver Diseases of Anhui Medical University (AMU), Anhui Medical University, Hefei, 230032, China
| | - Feng Yang
- School of Pharmacy, Anhui Medical University, Hefei, 230032, China; Institute for Liver Diseases of Anhui Medical University (AMU), Anhui Medical University, Hefei, 230032, China
| | - Xiao-feng Li
- School of Pharmacy, Anhui Medical University, Hefei, 230032, China; Institute for Liver Diseases of Anhui Medical University (AMU), Anhui Medical University, Hefei, 230032, China
| | - Yuan-yao Tian
- School of Pharmacy, Anhui Medical University, Hefei, 230032, China; Institute for Liver Diseases of Anhui Medical University (AMU), Anhui Medical University, Hefei, 230032, China
| | - Ming-ming Ni
- School of Pharmacy, Anhui Medical University, Hefei, 230032, China; Institute for Liver Diseases of Anhui Medical University (AMU), Anhui Medical University, Hefei, 230032, China
| | - Long-quan Zuo
- School of Pharmacy, Anhui Medical University, Hefei, 230032, China; Institute for Liver Diseases of Anhui Medical University (AMU), Anhui Medical University, Hefei, 230032, China
| | - Xiao-Ming Meng
- School of Pharmacy, Anhui Medical University, Hefei, 230032, China; Institute for Liver Diseases of Anhui Medical University (AMU), Anhui Medical University, Hefei, 230032, China
| | - Yan Huang
- School of Pharmacy, Anhui Medical University, Hefei, 230032, China; Institute for Liver Diseases of Anhui Medical University (AMU), Anhui Medical University, Hefei, 230032, China.
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Reddy BG, Dai Q, McNicholas CM, Fuller CM, Kappes JC, DeLucas LJ. Expression and purification of the alpha subunit of the epithelial sodium channel, ENaC. Protein Expr Purif 2015; 117:67-75. [PMID: 26394093 DOI: 10.1016/j.pep.2015.09.014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Revised: 09/05/2015] [Accepted: 09/11/2015] [Indexed: 01/19/2023]
Abstract
The epithelial sodium channel (ENaC) plays a critical role in maintaining Na(+) homeostasis in various tissues throughout the body. An understanding of the structure of the ENaC subunits has been developed from homology modeling based on the related acid sensing ion channel 1 (ASIC1) protein structure, as well as electrophysiological approaches. However, ENaC has several notable functional differences compared to ASIC1, thereby providing justification for determination of its three-dimensional structure. Unfortunately, this goal remains elusive due to several experimental challenges. Of the subunits that comprise a physiological hetero-trimeric αβγENaC, the α-subunit is unique in that it is capable of forming a homo-trimeric structure that conducts Na(+) ions. Despite functional and structural interest in αENaC, a key factor complicating structural studies has been its interaction with multiple other proteins, disrupting its homogeneity. In order to address this issue, a novel protocol was used to reduce the number of proteins that associate and co-purify with αENaC. In this study, we describe a novel expression system coupled with a two-step affinity purification approach using NiNTA, followed by a GFP antibody column as a rapid procedure to improve the purity and yield of rat αENaC.
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Affiliation(s)
- Bharat G Reddy
- Center for Biophysical Sciences and Engineering, University of Alabama at Birmingham, Birmingham, AL 35294, United States
| | - Qun Dai
- Dept. of Biochemistry, University of Alabama at Birmingham, Birmingham, AL 35294, United States; Dept. of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, United States
| | - Carmel M McNicholas
- Dept. of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294, United States
| | - Catherine M Fuller
- Dept. of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294, United States; Center for Biophysical Sciences and Engineering, University of Alabama at Birmingham, Birmingham, AL 35294, United States
| | - John C Kappes
- Center for Biophysical Sciences and Engineering, University of Alabama at Birmingham, Birmingham, AL 35294, United States; Dept. of Biochemistry, University of Alabama at Birmingham, Birmingham, AL 35294, United States; Dept. of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, United States; Birmingham Veterans Affairs Medical Center, Research Service, Birmingham, AL 35233, United States
| | - Lawrence J DeLucas
- Dept. of Optometry, University of Alabama at Birmingham, Birmingham, AL 35294, United States; Center for Biophysical Sciences and Engineering, University of Alabama at Birmingham, Birmingham, AL 35294, United States.
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Liu S, Cheng XY, Wang F, Liu CF. Acid-sensing ion channels: potential therapeutic targets for neurologic diseases. Transl Neurodegener 2015; 4:10. [PMID: 26029363 PMCID: PMC4449961 DOI: 10.1186/s40035-015-0031-3] [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: 11/07/2014] [Accepted: 05/14/2015] [Indexed: 01/14/2023] Open
Abstract
Maintaining the physiological pH of interstitial fluid is crucial for normal cellular functions. In disease states, tissue acidosis is a common pathologic change causing abnormal activation of acid-sensing ion channels (ASICs), which according to cumulative evidence, significantly contributes to inflammation, mitochondrial dysfunction, and other pathologic mechanisms (i.e., pain, stroke, and psychiatric conditions). Thus, it has become increasingly clear that ASICs are critical in the progression of neurologic diseases. This review is focused on the importance of ASICs as potential therapeutic targets in combating neurologic diseases.
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Affiliation(s)
- Sha Liu
- />Department of Neurology, the Second Affiliated Hospital of Soochow University, Soochow University, 1055 Sanxiang Road, Suzhou, 215004 China
| | - Xiao-Yu Cheng
- />Department of Neurology, the Second Affiliated Hospital of Soochow University, Soochow University, 1055 Sanxiang Road, Suzhou, 215004 China
| | - Fen Wang
- />Department of Neurology, the Second Affiliated Hospital of Soochow University, Soochow University, 1055 Sanxiang Road, Suzhou, 215004 China
- />Institute of Neuroscience, Soochow University, Suzhou, 215123 China
| | - Chun-Feng Liu
- />Department of Neurology, the Second Affiliated Hospital of Soochow University, Soochow University, 1055 Sanxiang Road, Suzhou, 215004 China
- />Institute of Neuroscience, Soochow University, Suzhou, 215123 China
- />Beijing Key Laboratory for Parkinson’s Disease, Beijing, 100053 China
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Jeggle P, Smith ESJ, Stewart AP, Haerteis S, Korbmacher C, Edwardson JM. Atomic force microscopy imaging reveals the formation of ASIC/ENaC cross-clade ion channels. Biochem Biophys Res Commun 2015; 464:38-44. [PMID: 26032502 DOI: 10.1016/j.bbrc.2015.05.091] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Accepted: 05/28/2015] [Indexed: 01/02/2023]
Abstract
ASIC and ENaC are co-expressed in various cell types, and there is evidence for a close association between them. Here, we used atomic force microscopy (AFM) to determine whether ASIC1a and ENaC subunits are able to form cross-clade hybrid ion channels. ASIC1a and ENaC could be co-isolated from detergent extracts of tsA 201 cells co-expressing the two subunits. Isolated proteins were incubated with antibodies against ENaC and Fab fragments against ASIC1a. AFM imaging revealed proteins that were decorated by both an antibody and a Fab fragment with an angle of ∼120° between them, indicating the formation of ASIC1a/ENaC heterotrimers.
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Affiliation(s)
- Pia Jeggle
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, United Kingdom
| | - Ewan St J Smith
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, United Kingdom
| | - Andrew P Stewart
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, United Kingdom
| | - Silke Haerteis
- Institut für Zelluläre und Molekulare Physiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Waldstrasse 6, 91054 Erlangen, Germany
| | - Christoph Korbmacher
- Institut für Zelluläre und Molekulare Physiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Waldstrasse 6, 91054 Erlangen, Germany
| | - J Michael Edwardson
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, United Kingdom.
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Buta A, Maximyuk O, Kovalskyy D, Sukach V, Vovk M, Ievglevskyi O, Isaeva E, Isaev D, Savotchenko A, Krishtal O. Novel Potent Orthosteric Antagonist of ASIC1a Prevents NMDAR-Dependent LTP Induction. J Med Chem 2015; 58:4449-61. [PMID: 25974655 DOI: 10.1021/jm5017329] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Acid sensing ion channels 1a (ASIC1a) are of crucial importance in numerous physiological and pathological processes in the brain. Here we demonstrate that novel 2-oxo-2H-chromene-3-carboxamidine derivative 5b, designed with molecular modeling approach, inhibits ASIC1a currents with an apparent IC50 of 27 nM when measured at pH 6.7. Acidification to 5.0 decreases the inhibition efficacy by up to 3 orders of magnitude. The 5b molecule not only shifts pH dependence of ASIC1a activation but also inhibits its maximal evoked response. These findings suggest that compound 5b binds to pH sensor of ASIC1a acting as orthosteric noncompetitive antagonist. At 100 nM, compound 5b completely inhibits induction of long-term potentiation (LTP) in CA3-CA1 but not in MF-CA3 synapses. These findings support the knockout data indicating the crucial modulatory role of ASIC1a channels in the NMDAR-dependent LTP and introduce a novel type of ASIC1a antagonists.
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Affiliation(s)
- Andriy Buta
- †Bogomoletz Institute of Physiology of NAS Ukraine, 4 Bogomoletz Str., 01024 Kyiv, Ukraine.,§State Key Laboratory for Molecular and Cellular Biology, 4 Bogomoletz Str., 01024 Kyiv, Ukraine
| | - Oleksandr Maximyuk
- †Bogomoletz Institute of Physiology of NAS Ukraine, 4 Bogomoletz Str., 01024 Kyiv, Ukraine.,§State Key Laboratory for Molecular and Cellular Biology, 4 Bogomoletz Str., 01024 Kyiv, Ukraine
| | - Dmytro Kovalskyy
- ∥ChemBio Center, Taras Shevchenko University of Kyiv, 67 Chervonotkatska Str., 02094 Kyiv, Ukraine
| | - Volodymyr Sukach
- ‡Institute of Organic Chemistry of NAS Ukraine, 5 Murmanska Str., 02660 Kyiv, Ukraine
| | - Mykhailo Vovk
- ‡Institute of Organic Chemistry of NAS Ukraine, 5 Murmanska Str., 02660 Kyiv, Ukraine
| | - Oleksandr Ievglevskyi
- †Bogomoletz Institute of Physiology of NAS Ukraine, 4 Bogomoletz Str., 01024 Kyiv, Ukraine
| | - Elena Isaeva
- †Bogomoletz Institute of Physiology of NAS Ukraine, 4 Bogomoletz Str., 01024 Kyiv, Ukraine
| | - Dmytro Isaev
- †Bogomoletz Institute of Physiology of NAS Ukraine, 4 Bogomoletz Str., 01024 Kyiv, Ukraine
| | - Alina Savotchenko
- †Bogomoletz Institute of Physiology of NAS Ukraine, 4 Bogomoletz Str., 01024 Kyiv, Ukraine
| | - Oleg Krishtal
- †Bogomoletz Institute of Physiology of NAS Ukraine, 4 Bogomoletz Str., 01024 Kyiv, Ukraine.,§State Key Laboratory for Molecular and Cellular Biology, 4 Bogomoletz Str., 01024 Kyiv, Ukraine
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Yang KQ, Lu CX, Xiao Y, Liu YX, Jiang XJ, Zhang X, Zhou XL. A novel frameshift mutation of epithelial sodium channel β-subunit leads to Liddle syndrome in an isolated case. Clin Endocrinol (Oxf) 2015; 82:611-4. [PMID: 25378078 DOI: 10.1111/cen.12650] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Revised: 09/23/2014] [Accepted: 10/28/2014] [Indexed: 11/28/2022]
Abstract
OBJECTIVE Liddle syndrome, an autosomal dominant form of monogenic hypertension, is attributed to mutations in the genes encoding β and γ subunits (SCNN1B and SCNN1G) of the epithelial sodium channel (ENaC). The aim of this study was to search for pathogenic mutations of SCNN1B and SCNN1G in an adolescent under the impression of Liddle syndrome and no family history of hypertension. DESIGN AND PATIENTS We screened the C-terminus of SCNN1B and SCNN1G in an adolescent with poorly controlled hypertension who was clinically diagnosed as having Liddle syndrome. We also screened for the mutation in his parents, 100 hypertensive patients and 100 controls. RESULTS Genetic analysis of SCNN1B revealed a frameshift mutation induced by insertion of an additional cytosine into a string of six located between codons 617 and 618, which is predicted to introduce a new termination codon at position 621 and produce a protein truncated by 20 amino acids. This frameshift mutation was not detected in the patient's parents, the 100 hypertensive patients or the 100 controls, indicating that this is a de novo mutation and not a common genetic polymorphism. There was no mutation of SCNN1G in any of the individuals examined. CONCLUSION Based on direct DNA sequencing, we identified a novel frameshift mutation in the βENaC gene in an isolated case of Liddle syndrome. Confirmation of the diagnosis and effective tailored treatment in the patient were achieved, implying that genetic testing is a useful tool to diagnose Liddle syndrome.
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Affiliation(s)
- Kun-Qi Yang
- Department of Cardiology, Fuwai Hospital, National Center for Cardiovascular Disease, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
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Molecular genetics of Liddle's syndrome. Clin Chim Acta 2014; 436:202-6. [PMID: 24882431 DOI: 10.1016/j.cca.2014.05.015] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2014] [Revised: 05/11/2014] [Accepted: 05/15/2014] [Indexed: 01/04/2023]
Abstract
Liddle's syndrome, an autosomal dominant form of monogenic hypertension, is characterized by salt-sensitive hypertension with early penetrance, hypokalemia, metabolic alkalosis, suppression of plasma rennin activity and aldosterone secretion, and a clear-cut response to epithelial sodium channel (ENaC) blockers but not spironolactone therapy. Our understanding of ENaCs and Na(+) transport defects has expanded greatly over the past two decades and provides detailed insight into the molecular basis of Liddle's syndrome. In this review, we offer an overview of recent advances in understanding the molecular genetics of Liddle's syndrome, involving mutation analysis, molecular mechanisms and genetic testing. The ENaC in the distal nephron is composed of α, β and γ subunits that share similar structures. Mutations associated with Liddle's syndrome are positioned in either β or γ subunits and disturb or truncate a conserved proline-rich sequence (i.e., PY motif), leading to constitutive activation of the ENaC. Genetic testing has made it possible to make accurate diagnoses and develop tailored therapies for mutation carriers.
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Rodríguez AA, Salceda E, Garateix AG, Zaharenko AJ, Peigneur S, López O, Pons T, Richardson M, Díaz M, Hernández Y, Ständker L, Tytgat J, Soto E. A novel sea anemone peptide that inhibits acid-sensing ion channels. Peptides 2014; 53:3-12. [PMID: 23764262 DOI: 10.1016/j.peptides.2013.06.003] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Revised: 06/01/2013] [Accepted: 06/03/2013] [Indexed: 12/19/2022]
Abstract
Sea anemones produce ion channels peptide toxins of pharmacological and biomedical interest. However, peptides acting on ligand-gated ion channels, including acid-sensing ion channel (ASIC) toxins, remain poorly explored. PhcrTx1 is the first compound characterized from the sea anemone Phymanthus crucifer, and it constitutes a novel ASIC inhibitor. This peptide was purified by gel filtration, ion-exchange and reversed-phase chromatography followed by biological evaluation on ion channels of isolated rat dorsal root ganglia (DRG) neurons using patch clamp techniques. PhcrTx1 partially inhibited ASIC currents (IC50∼100 nM), and also voltage-gated K(+) currents but the effects on the peak and on the steady state currents were lower than 20% in DRG neurons, at concentrations in the micromolar range. No significant effect was observed on Na(+) voltage-gated currents in DRG neurons. The N-terminal sequencing yielded 32 amino acid residues, with a molecular mass of 3477 Da by mass spectrometry. No sequence identity to other sea anemone peptides was found. Interestingly, the bioinformatic analysis of Cys-pattern and secondary structure arrangement suggested that this peptide presents an Inhibitor Cystine Knot (ICK) scaffold, which has been found in other venomous organisms such as spider, scorpions and cone snails. Our results show that PhcrTx1 represents the first member of a new structural group of sea anemones toxins acting on ASIC and, with much lower potency, on Kv channels. Moreover, this is the first report of an ICK peptide in cnidarians, suggesting that the occurrence of this motif in venomous animals is more ancient than expected.
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Affiliation(s)
| | - Emilio Salceda
- Instituto de Fisiología, Universidad Autónoma de Puebla, 14 sur 6301, CU, San Manuel, Puebla, Puebla CP 72750, Mexico.
| | | | | | - Steve Peigneur
- Laboratory of Toxicology, University of Leuven (KU Leuven), Campus Gasthuisberg O&N2, Herestraat 49, P.O. Box 922, 3000 Leuven, Belgium.
| | - Omar López
- Instituto de Fisiología, Universidad Autónoma de Puebla, 14 sur 6301, CU, San Manuel, Puebla, Puebla CP 72750, Mexico.
| | - Tirso Pons
- Centro Nacional de Investigaciones Oncológicas (CNIO), C/ Melchor Fernández Almagro 3, 28029 Madrid, Spain.
| | - Michael Richardson
- Fundação Ezequiel Dias-FUNED, Rua Conde Pereira Carneiro 80, CEP 30510-010 Belo Horizonte, MG, Brazil.
| | - Maylín Díaz
- Centro de Bioproductos Marinos (CEBIMAR), Loma y 37, Alturas del Vedado, CP 10400 Habana, Cuba.
| | - Yasnay Hernández
- Centro de Bioproductos Marinos (CEBIMAR), Loma y 37, Alturas del Vedado, CP 10400 Habana, Cuba.
| | - Ludger Ständker
- Kompetenzzentrum Ulm Peptide Pharmaceuticals (U-PEP), Universität Ulm (West), Albert-Einstein Allee 47, 89081 Ulm, Germany.
| | - Jan Tytgat
- Laboratory of Toxicology, University of Leuven (KU Leuven), Campus Gasthuisberg O&N2, Herestraat 49, P.O. Box 922, 3000 Leuven, Belgium.
| | - Enrique Soto
- Instituto de Fisiología, Universidad Autónoma de Puebla, 14 sur 6301, CU, San Manuel, Puebla, Puebla CP 72750, Mexico.
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Hobbs CA, Da Tan C, Tarran R. Does epithelial sodium channel hyperactivity contribute to cystic fibrosis lung disease? J Physiol 2013; 591:4377-87. [PMID: 23878362 DOI: 10.1113/jphysiol.2012.240861] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Airway epithelia absorb Na+ through the epithelial Na+ channel (ENaC) and secrete Cl- through the cystic fibrosis transmembrane conductance regulator (CFTR) anion channel. This balance maintains sufficient airway surface liquid hydration to permit efficient mucus clearance, which is needed to maintain sterility of the lung. Cystic fibrosis (CF) is a common autosomal recessive inherited disease caused by mutations in the CFTR gene that lead to the reduction or elimination of the CFTR protein. CF is a multi-organ disease that affects epithelia lining the intestines, lungs, pancreas, sweat ducts and vas deferens, among others. CF lungs are characterized by viscous, dehydrated mucus, persistent neutrophilia and chronic infections. ENaC is negatively regulated by CFTR and, in patients with CF, the absence of CFTR results in a double hit of reduced Cl-/HCO3- and H2O secretion as well as ENaC hyperactivity and increased Na+ and H2O absorption. Together, these effects are hypothesized to trigger mucus dehydration, resulting in a failure to clear mucus. Rehydrating CF mucus has become a recent clinical focus and yields important end-points for clinical trials. However, while ENaC hyperactivity in CF airways has been detected in vivo and in vitro, recent data have brought the role of ENaC in CF lung disease pathogenesis into question. This review will focus on our current understanding of the contribution of ENaC to CF pathogenesis.
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Affiliation(s)
- Carey A Hobbs
- R. Tarran: 7125 Thurston Bowles Building, UNC, Chapel Hill, NC 27599-7248, USA.
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Marino G, Kotsias B. Expression of the epithelial sodium channel sensitive to amiloride (ENaC) in normal and preeclamptic human placenta. Placenta 2013; 34:197-200. [DOI: 10.1016/j.placenta.2012.11.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/16/2012] [Revised: 10/22/2012] [Accepted: 11/11/2012] [Indexed: 10/27/2022]
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Downs CA, Trac DQ, Kreiner LH, Eaton AF, Johnson NM, Brown LA, Helms MN. Ethanol alters alveolar fluid balance via Nadph oxidase (NOX) signaling to epithelial sodium channels (ENaC) in the lung. PLoS One 2013; 8:e54750. [PMID: 23382956 PMCID: PMC3558518 DOI: 10.1371/journal.pone.0054750] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2012] [Accepted: 12/14/2012] [Indexed: 02/02/2023] Open
Abstract
Chronic alcohol consumption is associated with increased incidence of ICU-related morbidity and mortality, primarily from acute respiratory distress syndrome (ARDS). However, the mechanisms involved are unknown. One explanation is that alcohol regulates epithelial sodium channels (ENaC) via oxidant signaling to promote a pro- injury environment. We used small rodent models to mimic acute and chronic alcohol consumption and tested the hypothesis that ethanol (EtOH) would affect lung fluid clearance by up-regulating ENaC activity in the lung. Fluorescence labeling of rat lung slices and in vivo mouse lung revealed an increase in ROS production in response to acute EtOH exposure. Using western blots and fluorescein-5-maleimide labeling, we conclude that EtOH exposure modifies cysteines of α-ENaC while data from single channel patch clamp analysis confirm that 0.16% EtOH increased ENaC activity in rat alveolar cells. In vivo lung fluid clearance demonstrated a latent increase in fluid clearance in mice receiving EtOH diet. Ethanol mice given a tracheal instillation of LPS demonstrated early lung fluid clearance compared to caloric control mice and C57Bl/6 mice. Standard biochemical techniques reveal that chronic EtOH consumption resulted in greater protein expression of the catalytic gp91phox subunit and the obligate Rac1 protein. Collectively these data suggest that chronic EtOH consumption may lead to altered regulation of ENaC, contributing to a ‘pro-injury’ environment in the alcohol lung.
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Affiliation(s)
- Charles A Downs
- Nell Hodgson Woodruff School of Nursing, Emory University, Atlanta, Georgia, USA.
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Della Vecchia MC, Rued AC, Carattino MD. Gating transitions in the palm domain of ASIC1a. J Biol Chem 2013; 288:5487-95. [PMID: 23300086 DOI: 10.1074/jbc.m112.441964] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Acid-sensing ion channels (ASICs) are trimeric cation-selective proton-gated ion channels expressed in the central and peripheral nervous systems. The pore-forming transmembrane helices in these channels are linked by short loops to the palm domain in the extracellular region. Here, we explore the contribution to proton gating and desensitization of Glu-79 and Glu-416 in the palm domain of ASIC1a. Engineered Cys, Lys, and Gln substitutions at these positions shifted apparent proton affinity toward more acidic values. Double mutant cycle analysis indicated that Glu-79 and Glu-416 cooperatively facilitated pore opening in response to extracellular acidification. Channels bearing Cys at position 79 or 416 were irreversibly modified by thiol-reactive reagents in a state-dependent manner. Glu-79 and Glu-416 are located in β-strands 1 and 12, respectively. The covalent modification by (2-(trimethylammonium)ethyl) methanethiosulfonate bromide of Cys at position 79 impacted conformational changes associated with pore closing during desensitization, whereas the modification of Cys at position 416 affected conformational changes associated with proton gating. These results suggest that β-strands 1 and 12 contribute antagonistically to activation and desensitization of ASIC1a. Site-directed mutagenesis experiments indicated that the lower palm domain contracts in response to extracellular acidification. Taken together, our studies suggest that the lower palm domain mediates conformational movements that drive pore opening and closing events.
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Affiliation(s)
- Margaret C Della Vecchia
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, USA
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Gao L, Wang L, Liu Y, Zhou X, Hui R, Hu A. A family with Liddle syndrome caused by a novel missense mutation in the PY motif of the beta-subunit of the epithelial sodium channel. J Pediatr 2013; 162:166-70. [PMID: 22809657 DOI: 10.1016/j.jpeds.2012.06.017] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2012] [Revised: 05/23/2012] [Accepted: 06/07/2012] [Indexed: 11/17/2022]
Abstract
OBJECTIVE To identify the gene mutation in β and γ subunits of the epithelial sodium channel (ENaC) in an adolescent and family members with Liddle syndrome, an autosomal dominant form of secondary hypertension. STUDY DESIGN We screened an adolescent with severe hypertension who was clinically diagnosed with Liddle syndrome for mutations in the C-terminus of the SCNN1B and SCNN1G genes. We also screened for these mutations in his family members, in 100 hypertensive patients, and in 100 controls. RESULTS The index case, a 14-year-old boy, was diagnosed with Liddle syndrome by the identification of a novel missense mutation, P614L, in the PY motif of the β subunit of the ENaC. Testing of relatives considered at risk revealed 6 subjects heterozygous for the mutation. All genetically affected subjects had a history of severe hypertension as well as hypokalemia. No other variants in the β or γ subunits of the ENaC were detected. CONCLUSION Based on direct DNA sequencing, we have detected a novel mutation that causes Liddle syndrome. This confirms the diagnosis and helps guide effective therapy for this adolescent and his affected relatives. These findings provide further evidence that the conserved PY motif is critical to regulation of ENaC activity.
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Affiliation(s)
- Linggen Gao
- Department of Cardiology, FuWai Hospital and Cardiovascular Institute, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
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Pan JA, Fan Y, Gandhirajan RK, Madesh M, Zong WX. Hyperactivation of the mammalian degenerin MDEG promotes caspase-8 activation and apoptosis. J Biol Chem 2012; 288:2952-63. [PMID: 23239879 DOI: 10.1074/jbc.m112.441063] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Intracellular calcium overload plays a critical role in numerous pathological syndromes such as heart failure, brain ischemia, and stroke. Hyperactivation of the acid-sensing ion channels including degenerin/epithelial amiloride-sensitive sodium (DEG/ENaC) channels has been shown to elevate intracellular calcium and cause subsequent neuronal cell death that is independent of the canonical Egl-1/Ced-9/Ced-4/Ced-3 apoptotic pathway in Caenorhabditis elegans. In mammalian cells, hyperactivation of the DEG/ENaC channels can also lead to cell death, although the underlying mechanism remains largely unknown. Here, we use a tetracycline-inducible system to express the hyperactivation mutant of a mammalian DEG/ENaC channel protein, MDEG G430F, in murine kidney epithelial cells deficient in the key mitochondrial apoptotic proteins Bax and Bak. Remarkably, expression of MDEG G430F induces increased intracellular calcium, reactive oxygen species (ROS) production, and cell death. The MDEG G430F-induced cell death is blocked by the intracellular calcium chelator 1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (acetoxymethyl ester), ROS scavengers, and the caspase inhibitor z-VAD-fmk (where z and fmk are benzyloxycarbonyl and fluoromethyl ketone). Mechanistically, the intracellular calcium overload and ROS increase lead to the inhibition of proteasomal and autophagic protein degradation, which promotes the accumulation of protein aggregates containing caspase-8 and subsequent caspase-8 activation. As protein aggregation upon the inhibition of proteasomal and autophagic degradation pathways is mediated by the ubiquitin-binding protein SQSTM1/p62 and the autophagy-related protein LC3, silencing of p62 and LC3 protects cells from MDEG G430F-induced cell death. Our results uncover a new mechanism of caspase-8-mediated apoptosis induced by intracellular calcium overload that is dependent on the autophagy-related proteins LC3 and p62 upon hyperactivation of DEG/ENaC channels.
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Affiliation(s)
- Ji-An Pan
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, New York 11794, USA
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Two Drosophila DEG/ENaC channel subunits have distinct functions in gustatory neurons that activate male courtship. J Neurosci 2012; 32:11879-89. [PMID: 22915128 DOI: 10.1523/jneurosci.1376-12.2012] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Trimeric sodium channels of the DEG/ENaC family have important roles in neurons, but the specific functions of different subunits present in heteromeric channels are poorly understood. We previously reported that the Drosophila DEG/ENaC subunit Ppk25 is essential in a small subset of gustatory neurons for activation of male courtship behavior, likely through detection of female pheromones. Here we show that, like mutations in ppk25, mutations in another Drosophila DEG/ENaC subunit gene, nope, specifically impair male courtship of females. nope regulatory sequences drive reporter gene expression in gustatory neurons of the labellum wings, and legs, including all gustatory neurons in which ppk25 function is required for male courtship of females. In addition, gustatory-specific knockdown of nope impairs male courtship. Further, the impaired courtship response of nope mutant males to females is rescued by targeted expression of nope in the subset of gustatory neurons in which ppk25 functions. However, nope and ppk25 have nonredundant functions, as targeted expression of ppk25 does not compensate for the lack of nope and vice versa. Moreover, Nope and Ppk25 form specific complexes when coexpressed in cultured cells. Together, these data indicate that the Nope and Ppk25 polypeptides have specific, nonredundant functions in a subset of gustatory neurons required for activation of male courtship in response to females, and suggest the hypothesis that Nope and Ppk25 function as subunits of a heteromeric DEG/ENaC channel required for gustatory detection of female pheromones.
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Ji HL, Zhao RZ, Chen ZX, Shetty S, Idell S, Matalon S. δ ENaC: a novel divergent amiloride-inhibitable sodium channel. Am J Physiol Lung Cell Mol Physiol 2012; 303:L1013-26. [PMID: 22983350 DOI: 10.1152/ajplung.00206.2012] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The fourth subunit of the epithelial sodium channel, termed delta subunit (δ ENaC), was cloned in human and monkey. Increasing evidence shows that this unique subunit and its splice variants exhibit biophysical and pharmacological properties that are divergent from those of α ENaC channels. The widespread distribution of epithelial sodium channels in both epithelial and nonepithelial tissues implies a range of physiological functions. The altered expression of SCNN1D is associated with numerous pathological conditions. Genetic studies link SCNN1D deficiency with rare genetic diseases with developmental and functional disorders in the brain, heart, and respiratory systems. Here, we review the progress of research on δ ENaC in genomics, biophysics, proteomics, physiology, pharmacology, and clinical medicine.
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Affiliation(s)
- Hong-Long Ji
- Department of Cellular and Molecular Biology, University of Texas Health Science Center at Tyler, Tyler, Texas, USA.
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Chen J, Winarski KL, Myerburg MM, Pitt BR, Sheng S. Probing the structural basis of Zn2+ regulation of the epithelial Na+ channel. J Biol Chem 2012; 287:35589-35598. [PMID: 22930753 DOI: 10.1074/jbc.m112.394734] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Extracellular Zn(2+) activates the epithelial Na(+) channel (ENaC) by relieving Na(+) self-inhibition. However, a biphasic Zn(2+) dose response was observed, suggesting that Zn(2+) has dual effects on the channel (i.e. activating and inhibitory). To investigate the structural basis for this biphasic effect of Zn(2+), we examined the effects of mutating the 10 extracellular His residues of mouse γENaC. Four mutations within the finger subdomain (γH193A, γH200A, γH202A, and γH239A) significantly reduced the maximal Zn(2+) activation of the channel. Whereas γH193A, γH200A, and γH202A reduced the apparent affinity of the Zn(2+) activating site, γH239A diminished Na(+) self-inhibition and thus concealed the activating effects of Zn(2+). Mutation of a His residue within the palm subdomain (γH88A) abolished the low-affinity Zn(2+) inhibitory effect. Based on structural homology with acid-sensing ion channel 1, γAsp(516) was predicted to be in close proximity to γHis(88). Ala substitution of the residue (γD516A) blunted the inhibitory effect of Zn(2+). Our results suggest that external Zn(2+) regulates ENaC activity by binding to multiple extracellular sites within the γ-subunit, including (i) a high-affinity stimulatory site within the finger subdomain involving His(193), His(200), and His(202) and (ii) a low-affinity Zn(2+) inhibitory site within the palm subdomain that includes His(88) and Asp(516).
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Affiliation(s)
- Jingxin Chen
- Department of Medicine, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15261
| | - Katie L Winarski
- Department of Medicine, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15261
| | - Mike M Myerburg
- Department of Medicine, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15261
| | - Bruce R Pitt
- Department of Environmental and Occupational Health, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania 15261
| | - Shaohu Sheng
- Department of Medicine, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15261.
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Coxsackievirus and adenovirus receptor (CAR) mediates trafficking of acid sensing ion channel 3 (ASIC3) via PSD-95. Biochem Biophys Res Commun 2012; 425:13-8. [PMID: 22809504 DOI: 10.1016/j.bbrc.2012.07.033] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2012] [Accepted: 07/07/2012] [Indexed: 01/14/2023]
Abstract
We have previously shown that the Coxsackievirus and adenovirus receptor (CAR) can interact with post-synaptic density 95 (PSD-95) and localize PSD-95 to cell-cell junctions. We have also shown that activity of the acid sensing ion channel (ASIC3), a H(+)-gated cation channel that plays a role in mechanosensation and pain signaling, is negatively modulated by PSD-95 through a PDZ-based interaction. We asked whether CAR and ASIC3 simultaneously interact with PSD-95, and if so, whether co-expression of these proteins alters their cellular distribution and localization. Results indicate that CAR and ASIC3 co-immunoprecipitate only when co-expressed with PSD-95. CAR also brings both PSD-95 and ASIC3 to the junctions of heterologous cells. Moreover, CAR rescues PSD-95-mediated inhibition of ASIC3 currents. These data suggest that, in addition to activity as a viral receptor and adhesion molecule, CAR can play a role in trafficking proteins, including ion channels, in a PDZ-based scaffolding complex.
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