1
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Becker HM, Seidler UE. Bicarbonate secretion and acid/base sensing by the intestine. Pflugers Arch 2024; 476:593-610. [PMID: 38374228 PMCID: PMC11006743 DOI: 10.1007/s00424-024-02914-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Revised: 01/15/2024] [Accepted: 01/17/2024] [Indexed: 02/21/2024]
Abstract
The transport of bicarbonate across the enterocyte cell membrane regulates the intracellular as well as the luminal pH and is an essential part of directional fluid movement in the gut. Since the first description of "active" transport of HCO3- ions against a concentration gradient in the 1970s, the fundamental role of HCO3- transport for multiple intestinal functions has been recognized. The ion transport proteins have been identified and molecularly characterized, and knockout mouse models have given insight into their individual role in a variety of functions. This review describes the progress made in the last decade regarding novel techniques and new findings in the molecular regulation of intestinal HCO3- transport in the different segments of the gut. We discuss human diseases with defects in intestinal HCO3- secretion and potential treatment strategies to increase luminal alkalinity. In the last part of the review, the cellular and organismal mechanisms for acid/base sensing in the intestinal tract are highlighted.
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Affiliation(s)
- Holger M Becker
- Department of Gastroenterology, Hannover Medical School, 30625, Hannover, Germany
| | - Ursula E Seidler
- Department of Gastroenterology, Hannover Medical School, 30625, Hannover, Germany.
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2
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Zhang Z, Chen M, Zhan W, Chen Y, Wang T, Chen Z, Fu Y, Zhao G, Mao D, Ruan J, Yuan FL. Acid-sensing ion channel 1a modulation of apoptosis in acidosis-related diseases: implications for therapeutic intervention. Cell Death Discov 2023; 9:330. [PMID: 37666823 PMCID: PMC10477349 DOI: 10.1038/s41420-023-01624-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Revised: 07/28/2023] [Accepted: 08/22/2023] [Indexed: 09/06/2023] Open
Abstract
Acid-sensing ion channel 1a (ASIC1a), a prominent member of the acid-sensing ion channel (ASIC) superfamily activated by extracellular protons, is ubiquitously expressed throughout the human body, including the nervous system and peripheral tissues. Excessive accumulation of Ca2+ ions via ASIC1a activation may occur in the acidified microenvironment of blood or local tissues. ASIC1a-mediated Ca2+‑induced apoptosis has been implicated in numerous pathologies, including neurological disorders, cancer, and rheumatoid arthritis. This review summarizes the role of ASIC1a in the modulation of apoptosis via various signaling pathways across different disease states to provide insights for future studies on the underlying mechanisms and development of therapeutic strategies.
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Affiliation(s)
- Zhenyu Zhang
- Institute of Integrated Chinese and Western Medicine, Affiliated to Jiangnan University, Wuxi, Jiangsu, 214041, China
| | - Minnan Chen
- Nantong First People's Hospital, Nantong, 226001, China
| | - Wenjing Zhan
- The Key Laboratory of Anti-Inflammatory and Immune Medicine, Anhui Medical University, Hefei, 230032, China
| | - Yuechun Chen
- Institute of Integrated Chinese and Western Medicine, Affiliated to Jiangnan University, Wuxi, Jiangsu, 214041, China
| | - Tongtong Wang
- Institute of Integrated Chinese and Western Medicine, Affiliated to Jiangnan University, Wuxi, Jiangsu, 214041, China
| | - Zhonghua Chen
- Institute of Integrated Chinese and Western Medicine, Affiliated to Jiangnan University, Wuxi, Jiangsu, 214041, China
| | - Yifei Fu
- Institute of Integrated Chinese and Western Medicine, Affiliated to Jiangnan University, Wuxi, Jiangsu, 214041, China
| | - Gang Zhao
- Orthopaedic Institute, Wuxi 9th People's Hospital Affiliated to Soochow University, Wuxi, 214062, China
| | - Dong Mao
- Orthopaedic Institute, Wuxi 9th People's Hospital Affiliated to Soochow University, Wuxi, 214062, China.
| | - Jingjing Ruan
- Nantong First People's Hospital, Nantong, 226001, China.
- Department of Respiratory and Critical Care Medicine, The First Affiliated Hospital of Anhui Medical University, Hefei, 230022, People's Republic of China.
| | - Feng-Lai Yuan
- Institute of Integrated Chinese and Western Medicine, Affiliated to Jiangnan University, Wuxi, Jiangsu, 214041, China.
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3
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Hung CH, Chin Y, Fong YO, Lee CH, Han DS, Lin JH, Sun WH, Chen CC. Acidosis-related pain and its receptors as targets for chronic pain. Pharmacol Ther 2023; 247:108444. [PMID: 37210007 DOI: 10.1016/j.pharmthera.2023.108444] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 04/24/2023] [Accepted: 05/15/2023] [Indexed: 05/22/2023]
Abstract
Sensing acidosis is an important somatosensory function in responses to ischemia, inflammation, and metabolic alteration. Accumulating evidence has shown that acidosis is an effective factor for pain induction and that many intractable chronic pain diseases are associated with acidosis signaling. Various receptors have been known to detect extracellular acidosis and all express in the somatosensory neurons, such as acid sensing ion channels (ASIC), transient receptor potential (TRP) channels and proton-sensing G-protein coupled receptors. In addition to sense noxious acidic stimulation, these proton-sensing receptors also play a vital role in pain processing. For example, ASICs and TRPs are involved in not only nociceptive activation but also anti-nociceptive effects as well as some other non-nociceptive pathways. Herein, we review recent progress in probing the roles of proton-sensing receptors in preclinical pain research and their clinical relevance. We also propose a new concept of sngception to address the specific somatosensory function of acid sensation. This review aims to connect these acid-sensing receptors with basic pain research and clinical pain diseases, thus helping with better understanding the acid-related pain pathogenesis and their potential therapeutic roles via the mechanism of acid-mediated antinociception.
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Affiliation(s)
- Chih-Hsien Hung
- Department of Neurology, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan; School of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Yin Chin
- Department of Life Science & Institute of Genome Sciences, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Yi-On Fong
- Department of Neurology, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan; School of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Cheng-Han Lee
- Institute of Biomedical Sciences, Academia Sinica, Taipei 115, Taiwan
| | - Der-Shen Han
- Department of Physical Medicine and Rehabilitation, National Taiwan University Hospital, Bei-Hu Branch, Taipei, Taiwan
| | - Jiann-Her Lin
- Neuroscience Research Center, Taipei Medical University, Taipei, Taiwan; Department of Neurosurgery, Taipei Medical University Hospital, Taipei, Taiwan
| | - Wei-Hsin Sun
- Department of Life Science & Institute of Genome Sciences, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Chih-Cheng Chen
- Institute of Biomedical Sciences, Academia Sinica, Taipei 115, Taiwan; Neuroscience Research Center, Taipei Medical University, Taipei, Taiwan; Neuroscience Program of Academia Sinica, Academia Sinica, Taipei, Taiwan.
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4
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Chamniansawat S, Suksridechacin N, Thongon N. Current opinion on the regulation of small intestinal magnesium absorption. World J Gastroenterol 2023; 29:332-342. [PMID: 36687126 PMCID: PMC9846944 DOI: 10.3748/wjg.v29.i2.332] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/13/2022] [Revised: 10/25/2022] [Accepted: 11/19/2022] [Indexed: 01/06/2023] Open
Abstract
Magnesium (Mg2+) has an important role in numerous biological functions, and Mg2+ deficiency is associated with several diseases. Therefore, adequate intestinal absorption of Mg2+ is vital for health. The small intestine was previously thought to absorb digested Mg2+ exclusively through an unregulated paracellular mechanism, which is responsible for approximately 90% of total Mg2+ absorption. Recent studies, however, have revealed that the duodenum, jejunum, and ileum absorb Mg2+ through both transcellular and paracellular routes. Several regulatory factors of small intestinal Mg2+ uptake also have been explored, e.g., parathyroid hormone, fibroblast growth factor-23, apical acidity, proton pump inhibitor, and pH-sensing channel and receptors. The mechanistic factors underlying proton pump inhibitor suppression of small intestinal Mg2+, such as magnesiotropic protein dysfunction, higher mucosal bicarbonate secretion, Paneth cell dysfunction, and intestinal inflammation, are currently being explored. The potential role of small intestinal microbiomes in Mg2+ absorption has also been proposed. In this article, we reviewed the current knowledge on the mechanisms and regulatory factors of small intestinal Mg2+ absorption.
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Affiliation(s)
- Siriporn Chamniansawat
- Division of Anatomy, Department of Medical Sciences, Faculty of Allied Health Sciences, Burapha University, Muang 20131, Chonburi, Thailand
| | - Nasisorn Suksridechacin
- Biodiversity Research Centre, Thailand Institute of Scientific and Technological Research, Khlong Luang 12120, Pathum Thani, Thailand
| | - Narongrit Thongon
- Division of Physiology, Department of Medical Sciences, Faculty of Allied Health Sciences, Burapha University, Muang 20131, Chonburi, Thailand
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5
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Martí-Solans J, Børve A, Bump P, Hejnol A, Lynagh T. Peripheral and central employment of acid-sensing ion channels during early bilaterian evolution. eLife 2023; 12:81613. [PMID: 36821351 PMCID: PMC9949801 DOI: 10.7554/elife.81613] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Accepted: 01/08/2023] [Indexed: 02/24/2023] Open
Abstract
Nervous systems are endowed with rapid chemosensation and intercellular signaling by ligand-gated ion channels (LGICs). While a complex, bilaterally symmetrical nervous system is a major innovation of bilaterian animals, the employment of specific LGICs during early bilaterian evolution is poorly understood. We therefore questioned bilaterian animals' employment of acid-sensing ion channels (ASICs), LGICs that mediate fast excitatory responses to decreases in extracellular pH in vertebrate neurons. Our phylogenetic analysis identified an earlier emergence of ASICs from the overarching DEG/ENaC (degenerin/epithelial sodium channel) superfamily than previously thought and suggests that ASICs were a bilaterian innovation. Our broad examination of ASIC gene expression and biophysical function in each major bilaterian lineage of Xenacoelomorpha, Protostomia, and Deuterostomia suggests that the earliest bilaterian ASICs were probably expressed in the periphery, before being incorporated into the brain as it emerged independently in certain deuterostomes and xenacoelomorphs. The loss of certain peripheral cells from Ecdysozoa after they separated from other protostomes likely explains their loss of ASICs, and thus the absence of ASICs from model organisms Drosophila and Caenorhabditis elegans. Thus, our use of diverse bilaterians in the investigation of LGIC expression and function offers a unique hypothesis on the employment of LGICs in early bilaterian evolution.
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Affiliation(s)
| | - Aina Børve
- Department of Biological Sciences, University of BergenBergenNorway
| | - Paul Bump
- Hopkins Marine Station, Department of Biology, Stanford UniversityPacific GroveUnited States
| | - Andreas Hejnol
- Department of Biological Sciences, University of BergenBergenNorway
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Kaulich E, Carroll T, Ackley B, Tang YQ, Hardege I, Nehrke K, Schafer WR, Walker DS. Distinct roles for two Caenorhabditis elegans acid-sensing ion channels in an ultradian clock. eLife 2022; 11:75837. [PMID: 35666106 PMCID: PMC9374441 DOI: 10.7554/elife.75837] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Accepted: 06/01/2022] [Indexed: 11/13/2022] Open
Abstract
Biological clocks are fundamental to an organism's health, controlling periodicity of behaviour and metabolism. Here, we identify two acid-sensing ion channels, with very different proton sensing properties, and describe their role in an ultradian clock, the defecation motor program (DMP) of the nematode Caenorhabditis elegans. An ACD-5-containing channel, on the apical membrane of the intestinal epithelium, is essential for maintenance of luminal acidity, and thus the rhythmic oscillations in lumen pH. In contrast, the second channel, composed of FLR-1, ACD-3 and/or DEL-5, located on the basolateral membrane, controls the intracellular Ca2+ wave and forms a core component of the master oscillator that controls timing and rhythmicity of the DMP. flr-1 and acd-3/del-5 mutants show severe developmental and metabolic defects. We thus directly link the proton-sensing properties of these channels to their physiological roles in pH regulation and Ca2+ signalling, the generation of an ultradian oscillator, and its metabolic consequences.
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Affiliation(s)
- Eva Kaulich
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - Trae Carroll
- Department of Pathology and Lab Medicine, University of Rochester, Rochester, United States
| | - Brian Ackley
- Department of Molecular Biosciences, University of Kansas, Lawrence, United States
| | - Yi-Quan Tang
- Institutes of Brain Science, Fudan University, Shanghai, China
| | - Iris Hardege
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - Keith Nehrke
- Department of Medicine, University of Rochester, Rochester, United States
| | - William R Schafer
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
| | - Denise S Walker
- Neurobiology Division, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom
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7
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Zhang L, Zheng L, Yang X, Yao S, Wang H, An J, Jin H, Wen G, Tuo B. Pathology and physiology of acid‑sensitive ion channels in the digestive system (Review). Int J Mol Med 2022; 50:94. [PMID: 35616162 PMCID: PMC9170189 DOI: 10.3892/ijmm.2022.5150] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Accepted: 05/11/2022] [Indexed: 11/16/2022] Open
Abstract
As a major proton-gated cation channel, acid-sensitive ion channels (ASICs) can perceive large extracellular pH changes. ASICs play an important role in the occurrence and development of diseases of various organs and tissues including in the heart, brain, and gastrointestinal tract, as well as in tumor proliferation, invasion, and metastasis in acidosis and regulation of an acidic microenvironment. The permeability of ASICs to sodium and calcium ions is the basis of their physiological and pathological roles in the body. This review summarizes the physiological and pathological mechanisms of ASICs in digestive system diseases, which plays an important role in the early diagnosis, treatment, and prognosis of digestive system diseases related to ASIC expression.
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Affiliation(s)
- Li Zhang
- Department of Gastroenterology, Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou 563003, P.R. China
| | - Liming Zheng
- Department of Gastroenterology, Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou 563003, P.R. China
| | - Xingyue Yang
- Department of Gastroenterology, Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou 563003, P.R. China
| | - Shun Yao
- Department of Gastroenterology, Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou 563003, P.R. China
| | - Hui Wang
- Department of Gastroenterology, Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou 563003, P.R. China
| | - Jiaxing An
- Department of Gastroenterology, Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou 563003, P.R. China
| | - Hai Jin
- Department of Gastroenterology, Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou 563003, P.R. China
| | - Guorong Wen
- Department of Gastroenterology, Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou 563003, P.R. China
| | - Biguang Tuo
- Department of Gastroenterology, Affiliated Hospital of Zunyi Medical University, Zunyi, Guizhou 563003, P.R. China
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8
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Neural signalling of gut mechanosensation in ingestive and digestive processes. Nat Rev Neurosci 2022; 23:135-156. [PMID: 34983992 DOI: 10.1038/s41583-021-00544-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/16/2021] [Indexed: 12/29/2022]
Abstract
Eating and drinking generate sequential mechanosensory signals along the digestive tract. These signals are communicated to the brain for the timely initiation and regulation of diverse ingestive and digestive processes - ranging from appetite control and tactile perception to gut motility, digestive fluid secretion and defecation - that are vital for the proper intake, breakdown and absorption of nutrients and water. Gut mechanosensation has been investigated for over a century as a common pillar of energy, fluid and gastrointestinal homeostasis, and recent discoveries of specific mechanoreceptors, contributing ion channels and the well-defined circuits underlying gut mechanosensation signalling and function have further expanded our understanding of ingestive and digestive processes at the molecular and cellular levels. In this Review, we discuss our current understanding of the generation of mechanosensory signals from the digestive periphery, the neural afferent pathways that relay these signals to the brain and the neural circuit mechanisms that control ingestive and digestive processes, focusing on the four major digestive tract parts: the oral and pharyngeal cavities, oesophagus, stomach and intestines. We also discuss the clinical implications of gut mechanosensation in ingestive and digestive disorders.
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9
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Miedzybrodzka EL, Foreman RE, Lu VB, George AL, Smith CA, Larraufie P, Kay RG, Goldspink DA, Reimann F, Gribble FM. Stimulation of motilin secretion by bile, free fatty acids, and acidification in human duodenal organoids. Mol Metab 2021; 54:101356. [PMID: 34662713 PMCID: PMC8590067 DOI: 10.1016/j.molmet.2021.101356] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Revised: 09/06/2021] [Accepted: 10/07/2021] [Indexed: 12/23/2022] Open
Abstract
OBJECTIVE Motilin is a proximal small intestinal hormone with roles in gastrointestinal motility, gallbladder emptying, and hunger initiation. In vivo motilin release is stimulated by fats, bile, and duodenal acidification but the underlying molecular mechanisms of motilin secretion remain poorly understood. This study aimed to establish the key signaling pathways involved in the regulation of secretion from human motilin-expressing M-cells. METHODS Human duodenal organoids were CRISPR-Cas9 modified to express the fluorescent protein Venus or the Ca2+ sensor GCaMP7s under control of the endogenous motilin promoter. This enabled the identification and purification of M-cells for bulk RNA sequencing, peptidomics, calcium imaging, and electrophysiology. Motilin secretion from 2D organoid-derived cultures was measured by liquid chromatography-tandem mass spectrometry (LC-MS/MS), in parallel with other gut hormones. RESULTS Human duodenal M-cells synthesize active forms of motilin and acyl-ghrelin in organoid culture, and also co-express cholecystokinin (CCK). Activation of the bile acid receptor GPBAR1 stimulated a 3.4-fold increase in motilin secretion and increased action potential firing. Agonists of the long-chain fatty acid receptor FFA1 and monoacylglycerol receptor GPR119 stimulated secretion by 2.4-fold and 1.5-fold, respectively. Acidification (pH 5.0) was a potent stimulus of M-cell calcium elevation and electrical activity, an effect attributable to acid-sensing ion channels, and a modest inducer of motilin release. CONCLUSIONS This study presents the first in-depth transcriptomic and functional characterization of human duodenal motilin-expressing cells. We identify several receptors important for the postprandial and interdigestive regulation of motilin release.
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Affiliation(s)
- Emily L Miedzybrodzka
- Wellcome Trust - MRC Institute of Metabolic Science, Metabolic Research Laboratories, Addenbrooke's Hospital, Hills Road, Cambridge, CB2 0QQ, UK
| | - Rachel E Foreman
- Wellcome Trust - MRC Institute of Metabolic Science, Metabolic Research Laboratories, Addenbrooke's Hospital, Hills Road, Cambridge, CB2 0QQ, UK
| | - Van B Lu
- Wellcome Trust - MRC Institute of Metabolic Science, Metabolic Research Laboratories, Addenbrooke's Hospital, Hills Road, Cambridge, CB2 0QQ, UK
| | - Amy L George
- Wellcome Trust - MRC Institute of Metabolic Science, Metabolic Research Laboratories, Addenbrooke's Hospital, Hills Road, Cambridge, CB2 0QQ, UK
| | - Christopher A Smith
- Wellcome Trust - MRC Institute of Metabolic Science, Metabolic Research Laboratories, Addenbrooke's Hospital, Hills Road, Cambridge, CB2 0QQ, UK
| | - Pierre Larraufie
- Wellcome Trust - MRC Institute of Metabolic Science, Metabolic Research Laboratories, Addenbrooke's Hospital, Hills Road, Cambridge, CB2 0QQ, UK
| | - Richard G Kay
- Wellcome Trust - MRC Institute of Metabolic Science, Metabolic Research Laboratories, Addenbrooke's Hospital, Hills Road, Cambridge, CB2 0QQ, UK
| | - Deborah A Goldspink
- Wellcome Trust - MRC Institute of Metabolic Science, Metabolic Research Laboratories, Addenbrooke's Hospital, Hills Road, Cambridge, CB2 0QQ, UK
| | - Frank Reimann
- Wellcome Trust - MRC Institute of Metabolic Science, Metabolic Research Laboratories, Addenbrooke's Hospital, Hills Road, Cambridge, CB2 0QQ, UK.
| | - Fiona M Gribble
- Wellcome Trust - MRC Institute of Metabolic Science, Metabolic Research Laboratories, Addenbrooke's Hospital, Hills Road, Cambridge, CB2 0QQ, UK.
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10
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Shashni B, Tajika Y, Nagasaki Y. Design of enzyme-responsive short-chain fatty acid-based self-assembling drug for alleviation of type 2 diabetes mellitus. Biomaterials 2021; 275:120877. [PMID: 34062420 DOI: 10.1016/j.biomaterials.2021.120877] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 04/29/2021] [Accepted: 05/02/2021] [Indexed: 12/27/2022]
Abstract
Short-chain fatty acids (SCFAs), such as propionic and butyric acids have been touted as potential therapeutic interventions that can ameliorate diabetic pathogenesis. However, SCFAs are low-molecular-weight (LMW) compounds that have limited clinical use due to unfavorable pharmacokinetics, off-target effects, poor palatability and unpleasant odor. Hence, to improve the therapeutic utilization of SCFAs, the enzyme metabolizable block copolymers, [poly(ethylene glycol)-b-poly(vinyl ester)s], possessing propionate and butyrate esters were synthesized, which formed stable nanoparticles by self-assembling under physiological conditions. In this study, the therapeutic efficacy of propionic acid- and butyric acid-based self-assembling nanoparticles (PNP/BNP) was evaluated in a mouse model of type 2 diabetes mellitus through ad libitum drinking. The conventional antidiabetic drug, exenatide- and BNP-treated mice showed the highest glucose tolerance, whereas LMW SCFAs remained ineffective in normalizing glucose homeostasis. The better efficacy of BNP over the LMW SCFAs was attributable to (i) higher consumption of BNP than the LMW SCFAs by the mice (good palatability and odorless), (ii) prolonged residence time of BNP (48 h) in the gastro-intestinal tract (muco-adhesion) contributing to intestinal enzyme-mediated sustained release of butyric acid, and (iii) negligible off-target effects (no abrupt rise in the bloodstream). The aforementioned data suggest that SCFA-based nanoparticles are more potential therapeutic interventions than LMW SCFAs for metabolic diseases such as diabetes.
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Affiliation(s)
- Babita Shashni
- Department of Materials Science, Graduate School of Pure and Applied Sciences, University of Tsukuba, Tennoudai 1-1-1, Tsukuba, Ibaraki, 305-8573, Japan
| | - Yuya Tajika
- Department of Materials Science, Graduate School of Pure and Applied Sciences, University of Tsukuba, Tennoudai 1-1-1, Tsukuba, Ibaraki, 305-8573, Japan
| | - Yukio Nagasaki
- Department of Materials Science, Graduate School of Pure and Applied Sciences, University of Tsukuba, Tennoudai 1-1-1, Tsukuba, Ibaraki, 305-8573, Japan; Master's School of Medical Sciences, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tennoudai 1-1-1, Tsukuba, Ibaraki, 305-8573, Japan; Center for Research in Isotopes and Environmental Dynamics (CRiED), University of Tsukuba, Tennoudai 1-1-1, Tsukuba, Ibaraki, 305-8573, Japan.
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11
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Ruan N, Tribble J, Peterson AM, Jiang Q, Wang JQ, Chu XP. Acid-Sensing Ion Channels and Mechanosensation. Int J Mol Sci 2021; 22:ijms22094810. [PMID: 34062742 PMCID: PMC8125064 DOI: 10.3390/ijms22094810] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Revised: 04/29/2021] [Accepted: 04/30/2021] [Indexed: 12/16/2022] Open
Abstract
Acid-sensing ion channels (ASICs) are mainly proton-gated cation channels that are activated by pH drops and nonproton ligands. They are part of the degenerin/epithelial sodium channel superfamily due to their sodium permeability. Predominantly expressed in the central nervous system, ASICs are involved in synaptic plasticity, learning/memory, and fear conditioning. These channels have also been implicated in multiple disease conditions, including ischemic brain injury, multiple sclerosis, Alzheimer’s disease, and drug addiction. Recent research has illustrated the involvement of ASICs in mechanosensation. Mechanosensation is a form of signal transduction in which mechanical forces are converted into neuronal signals. Specific mechanosensitive functions have been elucidated in functional ASIC1a, ASIC1b, ASIC2a, and ASIC3. The implications of mechanosensation in ASICs indicate their subsequent involvement in functions such as maintaining blood pressure, modulating the gastrointestinal function, and bladder micturition, and contributing to nociception. The underlying mechanism of ASIC mechanosensation is the tether-gate model, which uses a gating-spring mechanism to activate ASIC responses. Further understanding of the mechanism of ASICs will help in treatments for ASIC-related pathologies. Along with the well-known chemosensitive functions of ASICs, emerging evidence has revealed that mechanosensitive functions of ASICs are important for maintaining homeostasis and contribute to various disease conditions.
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12
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Trampert DC, van de Graaf SFJ, Jongejan A, Oude Elferink RPJ, Beuers U. Hepatobiliary acid-base homeostasis: Insights from analogous secretory epithelia. J Hepatol 2021; 74:428-441. [PMID: 33342564 DOI: 10.1016/j.jhep.2020.10.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 10/03/2020] [Accepted: 10/19/2020] [Indexed: 12/14/2022]
Abstract
Many epithelia secrete bicarbonate-rich fluid to generate flow, alter viscosity, control pH and potentially protect luminal and intracellular structures from chemical stress. Bicarbonate is a key component of human bile and impaired biliary bicarbonate secretion is associated with liver damage. Major efforts have been undertaken to gain insight into acid-base homeostasis in cholangiocytes and more can be learned from analogous secretory epithelia. Extrahepatic examples include salivary and pancreatic duct cells, duodenocytes, airway and renal epithelial cells. The cellular machinery involved in acid-base homeostasis includes carbonic anhydrase enzymes, transporters of the solute carrier family, and intra- and extracellular pH sensors. This pH-regulatory system is orchestrated by protein-protein interactions, the establishment of an electrochemical gradient across the plasma membrane and bicarbonate sensing of the intra- and extracellular compartment. In this review, we discuss conserved principles identified in analogous secretory epithelia in the light of current knowledge on cholangiocyte physiology. We present a framework for cholangiocellular acid-base homeostasis supported by expression analysis of publicly available single-cell RNA sequencing datasets from human cholangiocytes, which provide insights into the molecular basis of pH homeostasis and dysregulation in the biliary system.
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Affiliation(s)
- David C Trampert
- Amsterdam UMC, University of Amsterdam, Department of Gastroenterology and Hepatology, Tytgat Institute for Liver and Intestinal Research, Amsterdam Gastroenterology Endocrinology Metabolism (AGEM), Meibergdreef 9, Amsterdam, the Netherlands
| | - Stan F J van de Graaf
- Amsterdam UMC, University of Amsterdam, Department of Gastroenterology and Hepatology, Tytgat Institute for Liver and Intestinal Research, Amsterdam Gastroenterology Endocrinology Metabolism (AGEM), Meibergdreef 9, Amsterdam, the Netherlands
| | - Aldo Jongejan
- Amsterdam UMC, University of Amsterdam, Department of Clinical Epidemiology, Biostatistics and Bioinformatics, Meibergdreef 9, Amsterdam, the Netherlands
| | - Ronald P J Oude Elferink
- Amsterdam UMC, University of Amsterdam, Department of Gastroenterology and Hepatology, Tytgat Institute for Liver and Intestinal Research, Amsterdam Gastroenterology Endocrinology Metabolism (AGEM), Meibergdreef 9, Amsterdam, the Netherlands
| | - Ulrich Beuers
- Amsterdam UMC, University of Amsterdam, Department of Gastroenterology and Hepatology, Tytgat Institute for Liver and Intestinal Research, Amsterdam Gastroenterology Endocrinology Metabolism (AGEM), Meibergdreef 9, Amsterdam, the Netherlands.
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13
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Xu Y, Chen F. Acid-Sensing Ion Channel-1a in Articular Chondrocytes and Synovial Fibroblasts: A Novel Therapeutic Target for Rheumatoid Arthritis. Front Immunol 2021; 11:580936. [PMID: 33584647 PMCID: PMC7876322 DOI: 10.3389/fimmu.2020.580936] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 12/14/2020] [Indexed: 12/19/2022] Open
Abstract
Acid-sensing ion channel 1a (ASIC1a) is a member of the extracellular H+-activated cation channel family. Emerging evidence has suggested that ASIC1a plays a crucial role in the pathogenesis of rheumatoid arthritis (RA). Specifically, ASIC1a could promote inflammation, synovial hyperplasia, articular cartilage, and bone destruction; these lead to the progression of RA, a chronic autoimmune disease characterized by chronic synovial inflammation and extra-articular lesions. In this review, we provided a brief overview of the molecular properties of ASIC1a, including the basic biological characteristics, tissue and cell distribution, channel blocker, and factors influencing the expression and function, and focused on the potential therapeutic targets of ASIC1a in RA and possible mechanisms of blocking ASIC1a to improve RA symptoms, such as regulation of apoptosis, autophagy, pyroptosis, and necroptosis of articular cartilage, and synovial inflammation and invasion of fibroblast-like cells in synovial tissue.
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Affiliation(s)
- Yayun Xu
- Department of Epidemiology and Biostatistics, School of Public Health, Anhui Medical University, Hefei, China.,The Key Laboratory of Major Autoimmune Diseases of Anhui Province, Anhui Institute of Innovative Drugs, School of Pharmacy, Anhui Medical University, Hefei, China.,The Key Laboratory of Anti-inflammatory and Immune Medicines, Ministry of Education, Hefei, China
| | - Feihu Chen
- Department of Epidemiology and Biostatistics, School of Public Health, Anhui Medical University, Hefei, China.,The Key Laboratory of Major Autoimmune Diseases of Anhui Province, Anhui Institute of Innovative Drugs, School of Pharmacy, Anhui Medical University, Hefei, China.,The Key Laboratory of Anti-inflammatory and Immune Medicines, Ministry of Education, Hefei, China
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14
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Takeuchi K, Ohashi Y, Amagase K. Roles of Up-Regulated Expression of ASIC3 in Sex Difference of Acid-Induced Duodenal HCO3 - Responses. Curr Pharm Des 2020; 26:3001-3009. [PMID: 32303171 DOI: 10.2174/1381612826666200417170319] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Accepted: 04/12/2020] [Indexed: 11/22/2022]
Abstract
Although the morbidity of ulcers is statistically higher in males than females, the mechanism of this difference remains unknown. Recent studies show that duodenal HCO3 - response to mucosal acidification is higher in females than males, and this may be a factor responsible for the sex difference in the mucosal protective mechanisms. In this article, we examined the duodenal HCO3 - responses to various stimuli in male and female rats, including estrogen, and reviewed the mechanisms responsible for the sex difference in the acid-induced HCO3 - secretion. Mucosal acidification was performed by exposing the duodenum to 10 mM HCl for 10 min. PGE2 was administered intravenously, while capsaicin was applied topically to the duodenum for 10 min. Tamoxifen was given s.c. 30 min before the acidification. Ovariectomy was performed 2 weeks before the experiments; half of the animals were given estrogen i.m. after the operation. Mucosal acidification increased duodenal HCO3 - secretion in male rats, and this response was inhibited by indomethacin and sensory deafferentation. Although no sex difference was found in HCO3 - responses to PGE2 and capsaicin, the response to acid was significantly greater in female than male rats. The different HCO3 - response to acid disappeared on ovariectomy, and this effect was totally reversed by the repeated administration of estrogen. The gene expression of ASIC3 in female rats was greater than in male rats and down-regulated by ovariectomy or tamoxifen treatment in an estradiol- dependent manner, while no sex difference was observed in TRPV1 and CFTR expressions. In conclusion, the acid-induced HCO3 - response is greater in female than male rats, and this phenomenon is not due to changes in PGE2 sensitivity or TRPV1/CFTR expressions but may be accounted for by increased expression of ASIC3 on sensory neurons, which is associated with the chronic influence of estrogen.
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Affiliation(s)
- Koji Takeuchi
- Division of Pathological Sciences, Department of Pharmacology and Experimental Therapeutics, Kyoto Pharmaceutical University, Kyoto 607-8414, Japan,General Incorporated Association, Kyoto Research Center for Gastrointestinal Diseases, Karasuma-Oike,
Kyoto 604-8106, Japan
| | - Yumi Ohashi
- Division of Pathological Sciences, Department of Pharmacology and Experimental Therapeutics, Kyoto Pharmaceutical University, Kyoto 607-8414, Japan
| | - Kikuko Amagase
- Division of Pathological Sciences, Department of Pharmacology and Experimental Therapeutics, Kyoto Pharmaceutical University, Kyoto 607-8414, Japan,Laboratory of Pharmacology and Pharmacotherapeutics, College of Pharmaceutical Sciences, Ritsumeikan
University, Shiga 525-8577, Japan
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15
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Zhang F, Wan H, Yang X, He J, Lu C, Yang S, Tuo B, Dong H. Molecular mechanisms of caffeine-mediated intestinal epithelial ion transports. Br J Pharmacol 2019; 176:1700-1716. [PMID: 30808064 DOI: 10.1111/bph.14640] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Revised: 01/10/2019] [Accepted: 01/31/2019] [Indexed: 01/14/2023] Open
Abstract
BACKGROUND AND PURPOSE As little is known about the effect of caffeine, one of the most widely consumed substances worldwide, on intestinal function, we aimed to study its action on intestinal anion secretion and the underlying molecular mechanisms. EXPERIMENTAL APPROACH Anion secretion and channel expression were examined in mouse duodenal epithelium by Ussing chambers and immunocytochemistry. Ca2+ imaging was also performed in intestinal epithelial cells (IECs). KEY RESULTS Caffeine (10 mM) markedly increased mouse duodenal short-circuit current (Isc ), which was attenuated by a removal of either Cl- or HCO3 - , Ca2+ -free serosal solutions and selective blockers of store-operated Ca2+ channels (SOC/Ca2+ release-activated Ca2+ channels), and knockdown of Orai1 channels on the serosal side of duodenal tissues. Caffeine induced SOC entry in IEC, which was inhibited by ruthenium red and selective blockers of SOC. Caffeine-stimulated duodenal Isc was inhibited by the endoplasmic reticulum Ca2+ chelator (N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine), selective blockers (ruthenium red and dantrolene) of ryanodine receptors (RyR), and of Ca2+ -activated Cl- channels (niflumic acid and T16A). There was synergism between cAMP and Ca2+ signalling, in which cAMP/PKA promoted caffeine/Ca2+ -mediated anion secretion. Expression of STIM1 and Orai1 was detected in mouse duodenal mucosa and human IECs. The Orai1 proteins were primarily co-located with the basolateral marker Na+ , K+ -ATPase. CONCLUSIONS AND IMPLICATIONS Caffeine stimulated intestinal anion secretion mainly through the RyR/Orai1/Ca2+ signalling pathway. There is synergism between cAMP/PKA and caffeine/Ca2+ -mediated anion secretion. Our findings suggest that a caffeine-mediated RyR/Orai1/Ca2+ pathway could provide novel potential drug targets to control intestinal anion secretion.
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Affiliation(s)
- Fenglian Zhang
- Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing, China
| | - Hanxing Wan
- Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing, China
| | - Xin Yang
- Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing, China
| | - Jialin He
- Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing, China
| | - Cheng Lu
- Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing, China
| | - Shiming Yang
- Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing, China
| | - Biguang Tuo
- Department of Gastroenterology, Affiliated Hospital, Zunyi Medical College, and Digestive Disease Institute of Guizhou Province, Zunyi, China
| | - Hui Dong
- Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing, China.,Department of Medicine, School of Medicine, University of California, San Diego, California, USA
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16
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Thongon N, Chamniansawat S. The inhibitory role of purinergic P2Y receptor on Mg 2+ transport across intestinal epithelium-like Caco-2 monolayer. J Physiol Sci 2019; 69:129-141. [PMID: 30032468 PMCID: PMC10717015 DOI: 10.1007/s12576-018-0628-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2018] [Accepted: 07/13/2018] [Indexed: 02/06/2023]
Abstract
The mechanism of proton pump inhibitors (PPIs) suppressing intestinal Mg2+ uptake is unknown. The present study aimed to investigate the role of purinergic P2Y receptors in the regulation of Mg2+ absorption in normal and omeprazole-treated intestinal epithelium-like Caco-2 monolayers. Omeprazole suppressed Mg2+ transport across Caco-2 monolayers. An agonist of the P2Y2 receptor, but not the P2Y4 or P2Y6 receptor, suppressed Mg2+ transport across control and omeprazole-treated monolayers. Omeprazole enhanced P2Y2 receptor expression in Caco-2 cells. Forskolin and P2Y2 receptor agonist markedly enhanced apical HCO3- secretion by control and omeprazole-treated monolayers. The P2Y2 receptor agonist suppressed Mg2+ transport and stimulated apical HCO3- secretion through the Gq-protein coupled-phospholipase C (PLC) dependent pathway. Antagonists of cystic fibrosis transmembrane conductance regulator (CFTR) and Na+-HCO3- cotransporter-1 (NBCe1) could nullify the inhibitory effect of P2Y2 receptor agonist on Mg2+ transport across control and omeprazole-treated Caco-2 monolayers. Our results propose an inhibitory role of P2Y2 on intestinal Mg2+ absorption.
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Affiliation(s)
- Narongrit Thongon
- Division of Physiology, Department of Biomedical Sciences, Faculty of Allied Health Sciences, Burapha University, 169 Long-Hard Bangsaen Rd, Saensook, Muang, Chonburi, 20131, Thailand.
| | - Siriporn Chamniansawat
- Division of Anatomy, Department of Biomedical Sciences, Faculty of Allied Health Sciences, Burapha University, 169 Long-Hard Bangsaen Rd, Saensook, Muang, Chonburi, 20131, Thailand
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17
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Helicobacter pylori infection downregulates duodenal CFTR and SLC26A6 expressions through TGFβ signaling pathway. BMC Microbiol 2018; 18:87. [PMID: 30119655 PMCID: PMC6098588 DOI: 10.1186/s12866-018-1230-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Accepted: 08/09/2018] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND The pathogenesis of Helicobacter pylori (H. pylori) infection-induced duodenal ulcer remains to be elucidated. Duodenal mucosal bicarbonate secretion is the most important protective factor against acid-induced mucosal injury. We previously revealed that H. pylori infection downregulated the expression and functional activity of duodenal mucosal cystic fibrosis transmembrane conductance regulator (CFTR) and solute linked carrier 26 gene family A6 (SLC26A6) which are the two key duodenal mucosal epithelial cellular bicarbonate transporters to mediate duodenal bicarbonate secretion. In this study, we investigated the mechanism of H. pylori infection-induced duodenal CFTR and SLC26A6 expression downregulation. RESULTS We found that H. pylori infection induced the increase of serum transforming growth factor β (TGFβ) level and duodenal mucosal TGFβ expression and the decrease of duodenal mucosal CFTR and SLC26A6 expressions in C57 BL/6 mice. The results from the experiments of human duodenal epithelial cells (SCBN) showed that H. pylori increased TGFβ production and decreased CFTR and SLC26A6 expressions in SCBN cells. TGFβ inhibitor SB431542 reversed the H. pylori-induced CFTR and SLC26A6 expression decreases. The further results showed that TGFβ directly decreased CFTR and SLC26A6 expressions in SCBN cells. TGFβ induced the phosphorylation of p38 mitogen-activated protein kinase (MAPK) and P38 MAPK inhibitor SB203580 reversed the TGFβ-induced CFTR and SLC26A6 expression decreases. CONCLUSIONS H. pylori infection downregulates duodenal epithelial cellular CFTR and SLC26A6 expressions through TGFβ-mediated P38 MAPK signaling pathway, which contributes to further elucidating the pathogenesis of H. pylori-associated duodenal ulcer.
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18
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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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19
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Cheng YR, Jiang BY, Chen CC. Acid-sensing ion channels: dual function proteins for chemo-sensing and mechano-sensing. J Biomed Sci 2018; 25:46. [PMID: 29793480 PMCID: PMC5966886 DOI: 10.1186/s12929-018-0448-y] [Citation(s) in RCA: 84] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Accepted: 05/15/2018] [Indexed: 12/22/2022] Open
Abstract
Background Acid-sensing ion channels (ASICs) are a group of amiloride-sensitive ligand-gated ion channels belonging to the family of degenerin/epithelial sodium channels. ASICs are predominantly expressed in both the peripheral and central nervous system and have been characterized as potent proton sensors to detect extracellular acidification in the periphery and brain. Main body Here we review the recent studies focusing on the physiological roles of ASICs in the nervous system. As the major acid-sensing membrane proteins in the nervous system, ASICs detect tissue acidosis occurring at tissue injury, inflammation, ischemia, stroke, and tumors as well as fatiguing muscle to activate pain-sensing nerves in the periphery and transmit pain signals to the brain. Arachidonic acid and lysophosphocholine have been identified as endogenous non-proton ligands activating ASICs in a neutral pH environment. On the other hand, ASICs are found involved in the tether model mechanotransduction, in which the extracellular matrix and cytoplasmic cytoskeletons act like a gating-spring to tether the mechanically activated ion channels and thus transmit the stimulus force to the channels. Accordingly, accumulating evidence has shown ASICs play important roles in mechanotransduction of proprioceptors, mechanoreceptors and nociceptors to monitor the homoeostatic status of muscle contraction, blood volume, and blood pressure as well as pain stimuli. Conclusion Together, ASICs are dual-function proteins for both chemosensation and mechanosensation involved in monitoring physiological homoeostasis and pathological signals.
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Affiliation(s)
- Yuan-Ren Cheng
- Department of Life Science, National Taiwan University, Taipei, 106, Taiwan.,Institute of Biomedical Sciences, Academia Sinica, 128, Academia Rd. Sec. 2, Taipei, 115, Taiwan
| | - Bo-Yang Jiang
- Department of Life Science, National Taiwan University, Taipei, 106, Taiwan.,Institute of Biomedical Sciences, Academia Sinica, 128, Academia Rd. Sec. 2, Taipei, 115, Taiwan
| | - Chih-Cheng Chen
- Department of Life Science, National Taiwan University, Taipei, 106, Taiwan. .,Institute of Biomedical Sciences, Academia Sinica, 128, Academia Rd. Sec. 2, Taipei, 115, Taiwan. .,Taiwan Mouse Clinic - National Comprehensive Mouse Phenotyping and Drug Testing Center, Academia Sinica, Taipei, 115, Taiwan.
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20
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Yang X, Wen G, Tuo B, Zhang F, Wan H, He J, Yang S, Dong H. Molecular mechanisms of calcium signaling in the modulation of small intestinal ion transports and bicarbonate secretion. Oncotarget 2017; 9:3727-3740. [PMID: 29423078 PMCID: PMC5790495 DOI: 10.18632/oncotarget.23197] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Accepted: 12/01/2017] [Indexed: 01/13/2023] Open
Abstract
Background and Purpose: Although Ca2+ signaling may stimulate small intestinal ion secretion, little is known about its critical role and the molecular mechanisms of Ca2+-mediated biological action. Key Results Activation of muscarinic receptors by carbachol(CCh) stimulated mouse duodenal Isc, which was significantly inhibited in Ca2+-free serosal solution and by several selective store-operated Ca2+ channels(SOC) blockers added to the serosal side of duodenal tissues. Furthermore, we found that CRAC/Orai channels may represent the molecular candidate of SOC in intestinal epithelium. CCh increased intracellular Ca2+ but not cAMP, and Ca2+ signaling mediated duodenal Cl- and HCO3- secretion in wild type mice but not in CFTR knockout mice. CCh induced duodenal ion secretion and stimulated PI3K/Akt activity in duodenal epithelium, all of which were inhibited by selective PI3K inhibitors with different structures. CCh-induced Ca2+ signaling also stimulated the phosphorylation of CFTR proteins and their trafficking to the plasma membrane of duodenal epithelial cells, which were inhibited again by selective PI3K inhibitors. Materials and Methods Functional, biochemical and morphological experiments were performed to examine ion secretion, PI3K/Akt and CFTR activity of mouse duodenal epithelium. Ca2+ imaging was performed on HT-29 cells. Conclusions and Implications Ca2+ signaling plays a critical role in intestinal ion secretion via CRAC/Orai-mediated SOCE mechanism on the serosal side of epithelium. We also demonstrated the molecular mechanisms of Ca2+ signaling in CFTR-mediated secretion via novel PI3K/Akt pathway. Our findings suggest new perspectives for drug targets to protect the upper GI tract and control liquid homeostasis in the small intestine.
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Affiliation(s)
- Xin Yang
- Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China
| | - Guorong Wen
- Department of Gastroenterology, Affiliated Hospital, Zunyi Medical College, and Digestive Disease Institute of Guizhou Province, Zunyi 563003, China
| | - Biguang Tuo
- Department of Gastroenterology, Affiliated Hospital, Zunyi Medical College, and Digestive Disease Institute of Guizhou Province, Zunyi 563003, China
| | - Fenglian Zhang
- Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China
| | - Hanxing Wan
- Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China
| | - Jialin He
- Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China
| | - Shiming Yang
- Department of Gastroenterology, Affiliated Hospital, Zunyi Medical College, and Digestive Disease Institute of Guizhou Province, Zunyi 563003, China
| | - Hui Dong
- Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China.,Department of Medicine, School of Medicine, University of California, San Diego, CA 92093, USA
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21
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He J, Yang X, Guo Y, Zhang F, Wan H, Sun X, Tuo B, Dong H. Ca 2+ signaling in HCO 3- secretion and protection of upper GI tract. Oncotarget 2017; 8:102681-102689. [PMID: 29254280 PMCID: PMC5731990 DOI: 10.18632/oncotarget.21840] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2017] [Accepted: 09/23/2017] [Indexed: 01/05/2023] Open
Abstract
The cytosolic calcium ([Ca2+]cyt) is one of the most important cell signaling that can modulate gastrointestinal (GI) epithelial secretion and promote GI mucosal wound repair. The GI mucosal bicarbonate secretion is the main mechanism of mucosal protection. Our research team has been working in this field and provided solid evidence for the important role of Ca2+ signaling in the regulation of GI epithelial secretion and the underlying molecular mechanisms. In this review, we attempt to systemically review the current status of our knowledge on the role of Ca2+ signaling in the regulation of intestinal bicarbonate secretion and in the upper GI epithelial protection. We expect that novel targets could be identified for drug development to better protect GI mucosa and treat mucosal injury with the advance in this filed.
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Affiliation(s)
- Jialin He
- Department of Gastroenterology, Affiliated Hospital, Zunyi Medical College, Zunyi, China
| | - Xin Yang
- Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing, China
| | - Yanjun Guo
- Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing, China
| | - Fenglian Zhang
- Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing, China
| | - Hanxing Wan
- Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing, China
| | - Xuemei Sun
- Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing, China
| | - Biguang Tuo
- Department of Gastroenterology, Affiliated Hospital, Zunyi Medical College, Zunyi, China
| | - Hui Dong
- Department of Gastroenterology, Affiliated Hospital, Zunyi Medical College, Zunyi, China.,Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing, China
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22
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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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23
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Lin SH, Sun WH, Chen CC. Genetic exploration of the role of acid-sensing ion channels. Neuropharmacology 2015; 94:99-118. [PMID: 25582292 DOI: 10.1016/j.neuropharm.2014.12.011] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Revised: 12/03/2014] [Accepted: 12/04/2014] [Indexed: 12/27/2022]
Abstract
Advanced gene targeting technology and related tools in mice have been incorporated into studies of acid-sensing ion channels (ASICs). A single ASIC subtype can be knocked out specifically and screened thoroughly for expression in the nervous system at the cellular level. Mapping studies have further shed light on the initiation and identification of related behavioral phenotypes. Here we review studies involving genetically engineered mouse models used to investigate the physiological function of individual ASIC subtypes: ASIC1 (and ASIC1a), ASIC2, ASIC3 and ASIC4. We discuss the detailed expression studies and significant phenotypes revealed with gene knockout for most known Asic subtypes. Each strategy designed to manipulate mouse genetics has advantages and disadvantages. We discuss the limitations of these Asic-knockout models and propose future directions to solve the genetic issues. This article is part of the Special Issue entitled 'Acid-Sensing Ion Channels in the Nervous System'.
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Affiliation(s)
- Shing-Hong Lin
- Institute of Life Sciences, National Defense Medical Center, Taipei 114, Taiwan; Institute of Biomedical Sciences, Academia Sinica, Taipei 115, Taiwan.
| | - Wei-Hsin Sun
- Department of Life Sciences, National Central University, Jhongli 32054, Taiwan.
| | - Chih-Cheng Chen
- Institute of Life Sciences, National Defense Medical Center, Taipei 114, Taiwan; Institute of Biomedical Sciences, Academia Sinica, Taipei 115, Taiwan; Taiwan Mouse Clinic, National Comprehensive Mouse Phenotyping and Drug Testing Center, Academia Sinica, Taipei 115, Taiwan.
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24
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Yu XW, Hu ZL, Ni M, Fang P, Zhang PW, Shu Q, Fan H, Zhou HY, Ni L, Zhu LQ, Chen JG, Wang F. Acid-sensing ion channels promote the inflammation and migration of cultured rat microglia. Glia 2014; 63:483-96. [DOI: 10.1002/glia.22766] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2013] [Accepted: 10/17/2014] [Indexed: 02/03/2023]
Affiliation(s)
- Xiao-Wei Yu
- Department of Pharmacology; School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology; Wuhan Hubei 430030 China
| | - Zhuang-Li Hu
- Department of Pharmacology; School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology; Wuhan Hubei 430030 China
- Key Laboratory of Neurological Diseases (HUST); Ministry of Education of China; Wuhan Hubei 430030 China
- The Key Laboratory for Drug Target Researches and Pharmacodynamic Evaluation of Hubei Province; Wuhan Hubei 430030 China
| | - Ming Ni
- Department of Pharmacology; School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology; Wuhan Hubei 430030 China
| | - Peng Fang
- Department of Pharmacology; School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology; Wuhan Hubei 430030 China
| | - Pei-Wei Zhang
- Department of Pharmacology; School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology; Wuhan Hubei 430030 China
| | - Qing Shu
- Department of Pharmacology; School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology; Wuhan Hubei 430030 China
| | - Hua Fan
- Department of Pharmacology; School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology; Wuhan Hubei 430030 China
| | - Hai-Yun Zhou
- Department of Pharmacology; School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology; Wuhan Hubei 430030 China
| | - Lan Ni
- Department of Pharmacology; School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology; Wuhan Hubei 430030 China
- Key Laboratory of Neurological Diseases (HUST); Ministry of Education of China; Wuhan Hubei 430030 China
- The Key Laboratory for Drug Target Researches and Pharmacodynamic Evaluation of Hubei Province; Wuhan Hubei 430030 China
| | - Ling-Qiang Zhu
- Key Laboratory of Neurological Diseases (HUST); Ministry of Education of China; Wuhan Hubei 430030 China
- The Institute of Brain Research, Huazhong University of Science and Technology; Wuhan 430030 China
| | - Jian-Guo Chen
- Department of Pharmacology; School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology; Wuhan Hubei 430030 China
- Key Laboratory of Neurological Diseases (HUST); Ministry of Education of China; Wuhan Hubei 430030 China
- The Key Laboratory for Drug Target Researches and Pharmacodynamic Evaluation of Hubei Province; Wuhan Hubei 430030 China
- The Institute of Brain Research, Huazhong University of Science and Technology; Wuhan 430030 China
| | - Fang Wang
- Department of Pharmacology; School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology; Wuhan Hubei 430030 China
- Key Laboratory of Neurological Diseases (HUST); Ministry of Education of China; Wuhan Hubei 430030 China
- The Key Laboratory for Drug Target Researches and Pharmacodynamic Evaluation of Hubei Province; Wuhan Hubei 430030 China
- The Institute of Brain Research, Huazhong University of Science and Technology; Wuhan 430030 China
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25
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Thongon N, Ketkeaw P, Nuekchob C. The roles of acid-sensing ion channel 1a and ovarian cancer G protein-coupled receptor 1 on passive Mg2+ transport across intestinal epithelium-like Caco-2 monolayers. J Physiol Sci 2014; 64:129-39. [PMID: 24375028 PMCID: PMC10717441 DOI: 10.1007/s12576-013-0301-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2013] [Accepted: 12/10/2013] [Indexed: 02/06/2023]
Abstract
Intestinal passive Mg(2+) absorption, which is vital for normal Mg(2+) homeostasis, has been shown to be regulated by luminal proton. We aimed to study the regulatory role of intestinal acid sensors in paracellular passive Mg(2+) transport. Omeprazole enhanced the expressions of acid-sensing ion channel 1a (ASIC1a), ovarian cancer G protein-coupled receptor 1 (OGR1), and transient receptor potential vanilloid 4 in Caco-2 cells. It also inhibited passive Mg(2+) transport across Caco-2 monolayers. The expression and activation of OGR1 resulted in the stimulation of passive Mg(2+) transport via phospholipase C- and protein kinase C-dependent pathways. ASIC1a activation, on the other hand, enhanced apical HCO3 (-) secretion that led, at least in part, by a Ca(2+)-dependent pathway to an inhibition of paracellular Mg(2+) absorption. Our results provided supporting evidence for the roles of OGR1 and ASIC1a in the regulation of intestinal passive Mg(2+) absorption.
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Affiliation(s)
- Narongrit Thongon
- Division of Physiology, Department of Biomedical Sciences, Faculty of Allied Health Sciences, Burapha University, 169 Long-Hard Bangsaen Rd., Saensook, Muang, Chonburi, 20131, Thailand,
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26
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Jung J, Lee MG. Role of calcium signaling in epithelial bicarbonate secretion. Cell Calcium 2014; 55:376-84. [PMID: 24598807 DOI: 10.1016/j.ceca.2014.02.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2014] [Revised: 02/03/2014] [Accepted: 02/04/2014] [Indexed: 12/24/2022]
Abstract
Transepithelial bicarbonate secretion plays a key role in the maintenance of fluid and protein secretion from epithelial cells and the protection of the epithelial cell surface from various pathogens. Epithelial bicarbonate secretion is mainly under the control of cAMP and calcium signaling. While the physiological roles and molecular mechanisms of cAMP-induced bicarbonate secretion are relatively well defined, those induced by calcium signaling remain poorly understood in most epithelia. The present review summarizes the current status of knowledge on the role of calcium signaling in epithelial bicarbonate secretion. Specifically, this review introduces how cytosolic calcium signaling can increase bicarbonate secretion by regulating membrane transport proteins and how it synergizes with cAMP-induced mechanisms in epithelial cells. In addition, tissue-specific variations in the pancreas, salivary glands, intestines, bile ducts, and airways are discussed. We hope that the present report will stimulate further research into this important topic. These studies will provide the basis for future medicines for a wide spectrum of epithelial disorders including cystic fibrosis, Sjögren's syndrome, and chronic pancreatitis.
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Affiliation(s)
- Jinsei Jung
- Department of Pharmacology and Brain Korea 21 Plus Project for Medical Sciences, Yonsei University College of Medicine, Seoul 120-752, Republic of Korea; Department of Otorhinolaryngology, Yonsei University College of Medicine, Seoul 120-752, Republic of Korea
| | - Min Goo Lee
- Department of Pharmacology and Brain Korea 21 Plus Project for Medical Sciences, Yonsei University College of Medicine, Seoul 120-752, Republic of Korea.
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27
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Persson PB, Persson AB. A matter of taste. Acta Physiol (Oxf) 2013; 207:203-5. [PMID: 23297704 DOI: 10.1111/apha.12023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- P B Persson
- Institute of Vegetative Physiology, Charité-Universitaetsmedizin Berlin, Berlin, Germany
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28
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Cohen L, Asraf H, Sekler I, Hershfinkel M. Extracellular pH regulates zinc signaling via an Asp residue of the zinc-sensing receptor (ZnR/GPR39). J Biol Chem 2012; 287:33339-50. [PMID: 22879599 DOI: 10.1074/jbc.m112.372441] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Zinc activates a specific Zn(2+)-sensing receptor, ZnR/GPR39, and thereby triggers cellular signaling leading to epithelial cell proliferation and survival. Epithelial cells that express ZnR, particularly colonocytes, face frequent changes in extracellular pH that are of physiological and pathological implication. Here we show that the ZnR/GPR39-dependent Ca(2+) responses in HT29 colonocytes were maximal at pH 7.4 but were reduced by about 50% at pH 7.7 and by about 62% at pH 7.1 and were completely abolished at pH 6.5. Intracellular acidification did not attenuate ZnR/GPR39 activity, indicating that the pH sensor of this protein is located on an extracellular domain. ZnR/GPR39-dependent activation of extracellular-regulated kinase (ERK)1/2 or AKT pathways was abolished at acidic extracellular pH of 6.5. A similar inhibitory effect was monitored for the ZnR/GPR39-dependent up-regulation of Na(+)/H(+) exchange activity at pH 6.5. Focusing on residues putatively facing the extracellular domain, we sought to identify the pH sensor of ZnR/GPR39. Replacing the histidine residues forming the Zn(2+) binding site, His(17) or His(19), or other extracellular-facing histidines to alanine residues did not abolish the pH dependence of ZnR/GPR39. In contrast, replacing Asp(313) with alanine resulted in similar Ca(2+) responses triggered by ZnR/GPR39 at pH 7.4 or 6.5. This mutant also showed similar activation of ERK1/2 and AKT pathways, and ZnR-dependent up-regulation of Na(+)/H(+) exchange at pH 7.4 and pH 6.5. Substitution of Asp(313) to His or Glu residues restored pH sensitivity of the receptor. This indicates that Asp(313), which was shown to modulate Zn(2+) binding, is an essential residue of the pH sensor of GPR39. In conclusion, ZnR/GPR39 is tuned to sense physiologically relevant changes in extracellular pH that thus regulate ZnR-dependent signaling and ion transport activity.
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Affiliation(s)
- Limor Cohen
- Department of Morphology, Faculty of Health Sciences, Ben Gurion University of the Negev, Beer-Sheva 84105, Israel
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29
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Abstract
Acid-sensing ion channels (ASICs) are present in neurons and may contribute to chemoreception. Among six subunits of ASICs, ASIC1 is mainly expressed in the central nervous system. Recently, multiple sites in the brain including the lateral hypothalamus (LH) have been found to be sensitive to extracellular acidification. Since LH contains orexin neurons and innervates the medulla respiratory center, we hypothesize that ASIC1 is expressed on the orexin neuron and contributes to acid-induced increase in respiratory drive. To test this hypothesis, we used double immunofluorescence to determine whether ASIC1 is expressed on orexin neurons in the LH, and assessed integrated phrenic nerve discharge (iPND) in intact rats in response to acidification of the LH. We found that ASIC1 was co-localized with orexinA in the LH. Microinjection of acidified artificial cerebrospinal fluid increased the amplitude of iPND by 70% (pH 7.4 v.s. pH 6.5:1.05±0.12 v.s. 1.70±0.10, n = 6, P<0.001) and increased the respiratory drive (peak amplitude of iPND/inspiratory time, PA/Ti) by 40% (1.10±0.23 v.s. 1.50±0.38, P<0.05). This stimulatory effect was abolished by blocking ASIC1 with a nonselective inhibitor (amiloride 10 mM), a selective inhibitor (PcTX1, 10 nM) or by damaging orexin neurons in the LH. Current results support our hypothesis that the orexin neuron in the LH can exert an excitation on respiration via ASIC1 during local acidosis. Since central acidification is involved in breathing dysfunction in a variety of pulmonary diseases, understanding its underlying mechanism may improve patient management.
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30
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Song N, Zhang G, Geng W, Liu Z, Jin W, Li L, Cao Y, Zhu D, Yu J, Shen L. Acid sensing ion channel 1 in lateral hypothalamus contributes to breathing control. PLoS One 2012; 7:e39982. [PMID: 22792205 PMCID: PMC3391217 DOI: 10.1371/journal.pone.0039982] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2012] [Accepted: 05/30/2012] [Indexed: 12/20/2022] Open
Abstract
Acid-sensing ion channels (ASICs) are present in neurons and may contribute to chemoreception. Among six subunits of ASICs, ASIC1 is mainly expressed in the central nervous system. Recently, multiple sites in the brain including the lateral hypothalamus (LH) have been found to be sensitive to extracellular acidification. Since LH contains orexin neurons and innervates the medulla respiratory center, we hypothesize that ASIC1 is expressed on the orexin neuron and contributes to acid-induced increase in respiratory drive. To test this hypothesis, we used double immunofluorescence to determine whether ASIC1 is expressed on orexin neurons in the LH, and assessed integrated phrenic nerve discharge (iPND) in intact rats in response to acidification of the LH. We found that ASIC1 was co-localized with orexinA in the LH. Microinjection of acidified artificial cerebrospinal fluid increased the amplitude of iPND by 70% (pH 7.4 v.s. pH 6.5:1.05±0.12 v.s. 1.70±0.10, n = 6, P<0.001) and increased the respiratory drive (peak amplitude of iPND/inspiratory time, PA/Ti) by 40% (1.10±0.23 v.s. 1.50±0.38, P<0.05). This stimulatory effect was abolished by blocking ASIC1 with a nonselective inhibitor (amiloride 10 mM), a selective inhibitor (PcTX1, 10 nM) or by damaging orexin neurons in the LH. Current results support our hypothesis that the orexin neuron in the LH can exert an excitation on respiration via ASIC1 during local acidosis. Since central acidification is involved in breathing dysfunction in a variety of pulmonary diseases, understanding its underlying mechanism may improve patient management.
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Affiliation(s)
- Nana Song
- Department of Physiology and Pathophysiology, Shanghai Medical College, Fudan University, Shanghai, China
| | - Guihong Zhang
- Department of Physiology and Pathophysiology, Shanghai Medical College, Fudan University, Shanghai, China
| | - Wenye Geng
- Department of Physiology and Pathophysiology, Shanghai Medical College, Fudan University, Shanghai, China
| | - Zibing Liu
- Department of Physiology and Pathophysiology, Shanghai Medical College, Fudan University, Shanghai, China
| | - Weizhong Jin
- Department of Physiology and Pathophysiology, Shanghai Medical College, Fudan University, Shanghai, China
| | - Li Li
- Department of Physiology and Pathophysiology, Shanghai Medical College, Fudan University, Shanghai, China
| | - Yinxiang Cao
- Department of Physiology and Pathophysiology, Shanghai Medical College, Fudan University, Shanghai, China
| | - Danian Zhu
- Department of Physiology and Pathophysiology, Shanghai Medical College, Fudan University, Shanghai, China
| | - Jerry Yu
- Department of Physiology and Pathophysiology, Shanghai Medical College, Fudan University, Shanghai, China
- Department of Pulmonary Medicine, University of Louisville, Louisville, Kentucky, United States of America
| | - Linlin Shen
- Department of Physiology and Pathophysiology, Shanghai Medical College, Fudan University, Shanghai, China
- * E-mail:
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31
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Gillies RJ, Verduzco D, Gatenby RA. Evolutionary dynamics of carcinogenesis and why targeted therapy does not work. Nat Rev Cancer 2012; 12:487-93. [PMID: 22695393 PMCID: PMC4122506 DOI: 10.1038/nrc3298] [Citation(s) in RCA: 457] [Impact Index Per Article: 38.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
All malignant cancers, whether inherited or sporadic, are fundamentally governed by Darwinian dynamics. The process of carcinogenesis requires genetic instability and highly selective local microenvironments, the combination of which promotes somatic evolution. These microenvironmental forces, specifically hypoxia, acidosis and reactive oxygen species, are not only highly selective, but are also able to induce genetic instability. As a result, malignant cancers are dynamically evolving clades of cells living in distinct microhabitats that almost certainly ensure the emergence of therapy-resistant populations. Cytotoxic cancer therapies also impose intense evolutionary selection pressures on the surviving cells and thus increase the evolutionary rate. Importantly, the principles of Darwinian dynamics also embody fundamental principles that can illuminate strategies for the successful management of cancer.
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Affiliation(s)
- Robert J Gillies
- Department of Cancer Physiology and Biophysics, H. Lee Moffitt Cancer Center and Research Institute, Tampa FL 33602, USA.
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32
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Abstract
The epithelial Na(+) channel (ENaC) and acid-sensitive ion channel (ASIC) branches of the ENaC/degenerin superfamily of cation channels have drawn increasing attention as potential therapeutic targets in a variety of diseases and conditions. Originally thought to be solely expressed in fluid absorptive epithelia and in neurons, it has become apparent that members of this family exhibit nearly ubiquitous expression. Therapeutic opportunities range from hypertension, due to the role of ENaC in maintaining whole body salt and water homeostasis, to anxiety disorders and pain associated with ASIC activity. As a physiologist intrigued by the fundamental mechanics of salt and water transport, it was natural that Dale Benos, to whom this series of reviews is dedicated, should have been at the forefront of research into the amiloride-sensitive sodium channel. The cloning of ENaC and subsequently the ASIC channels has revealed a far wider role for this channel family than was previously imagined. In this review, we will discuss the known and potential roles of ENaC and ASIC subunits in the wide variety of pathologies in which these channels have been implicated. Some of these, such as the role of ENaC in Liddle's syndrome are well established, others less so; however, all are related in that the fundamental defect is due to inappropriate channel activity.
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Affiliation(s)
- Yawar J Qadri
- Department of Physiology and Biophysics, University of Alabama at Birmingham, AL 35294, USA
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33
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Hegyi P, Maléth J, Venglovecz V, Rakonczay Z. Pancreatic ductal bicarbonate secretion: challenge of the acinar Acid load. Front Physiol 2011; 2:36. [PMID: 21808623 PMCID: PMC3139102 DOI: 10.3389/fphys.2011.00036] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2011] [Accepted: 06/22/2011] [Indexed: 02/03/2023] Open
Abstract
Acinar and ductal cells of the exocrine pancreas form a close functional unit. Although most studies contain data either on acinar or ductal cells, an increasing number of evidence highlights the importance of the pancreatic acinar-ductal functional unit. One of the best examples for this functional unit is the regulation of luminal pH by both cell types. Protons co-released during exocytosis from acini cause significant acidosis, whereas, bicarbonate secreted by ductal cells cause alkalization in the lumen. This suggests that the first and probably one of the most important role of bicarbonate secretion by pancreatic ductal cells is not only to neutralize the acid chyme entering into the duodenum from the stomach, but to neutralize acidic content secreted by acinar cells. To accomplish this role, it is more than likely that ductal cells have physiological sensing mechanisms which would allow them to regulate luminal pH. To date, four different classes of acid-sensing ion channels have been identified in the gastrointestinal tract (transient receptor potential ion channels, two-pore domain potassium channel, ionotropic purinoceptor and acid-sensing ion channel), however, none of these have been studied in pancreatic ductal cells. In this mini-review, we summarize our current knowledge of these channels and urge scientists to characterize ductal acid-sensing mechanisms and also to investigate the challenge of the acinar acid load on ductal cells.
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Affiliation(s)
- Péter Hegyi
- First Department of Medicine, University of Szeged Szeged, Hungary
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