1
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Manchester AC, Ammons DT, Lappin MR, Dow S. Single cell transcriptomic analysis of the canine duodenum in chronic inflammatory enteropathy and health. Front Immunol 2024; 15:1397590. [PMID: 38933260 PMCID: PMC11199541 DOI: 10.3389/fimmu.2024.1397590] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2024] [Accepted: 05/27/2024] [Indexed: 06/28/2024] Open
Abstract
Chronic inflammatory enteropathy (CIE) is a common condition in dogs causing recurrent or persistent gastrointestinal clinical signs. Pathogenesis is thought to involve intestinal mucosal inflammatory infiltrates, but histopathological evaluation of intestinal biopsies from dogs with CIE fails to guide treatment, inform prognosis, or correlate with clinical remission. We employed single-cell RNA sequencing to catalog and compare the diversity of cells present in duodenal mucosal endoscopic biopsies from 3 healthy dogs and 4 dogs with CIE. Through characterization of 35,668 cells, we identified 31 transcriptomically distinct cell populations, including T cells, epithelial cells, and myeloid cells. Both healthy and CIE samples contributed to each cell population. T cells were broadly subdivided into GZMAhigh (putatively annotated as tissue resident) and IL7Rhigh (putatively annotated as non-resident) T cell categories, with evidence of a skewed proportion favoring an increase in the relative proportion of IL7Rhigh T cells in CIE dogs. Among the myeloid cells, neutrophils from CIE samples exhibited inflammatory (SOD2 and IL1A) gene expression signatures. Numerous differentially expressed genes were identified in epithelial cells, with gene set enrichment analysis suggesting enterocytes from CIE dogs may be undergoing stress responses and have altered metabolic properties. Overall, this work reveals the previously unappreciated cellular heterogeneity in canine duodenal mucosa and provides new insights into molecular mechanisms which may contribute to intestinal dysfunction in CIE. The cell type gene signatures developed through this study may also be used to better understand the subtleties of canine intestinal physiology in health and disease.
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Affiliation(s)
- Alison C. Manchester
- Colorado State University, Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Fort Collins, CO, United States
| | - Dylan T. Ammons
- Colorado State University, Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Fort Collins, CO, United States
| | - Michael R. Lappin
- Colorado State University, Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Fort Collins, CO, United States
| | - Steven Dow
- Colorado State University, Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Fort Collins, CO, United States
- Colorado State University, Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Fort Collins, CO, United States
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2
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Ott S, Xu S, Lee N, Hong I, Anns J, Suresh DD, Zhang Z, Zhang X, Harion R, Ye W, Chandramouli V, Jesuthasan S, Saheki Y, Claridge-Chang A. Kalium channelrhodopsins effectively inhibit neurons. Nat Commun 2024; 15:3480. [PMID: 38658537 PMCID: PMC11043423 DOI: 10.1038/s41467-024-47203-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Accepted: 03/18/2024] [Indexed: 04/26/2024] Open
Abstract
The analysis of neural circuits has been revolutionized by optogenetic methods. Light-gated chloride-conducting anion channelrhodopsins (ACRs)-recently emerged as powerful neuron inhibitors. For cells or sub-neuronal compartments with high intracellular chloride concentrations, however, a chloride conductance can have instead an activating effect. The recently discovered light-gated, potassium-conducting, kalium channelrhodopsins (KCRs) might serve as an alternative in these situations, with potentially broad application. As yet, KCRs have not been shown to confer potent inhibitory effects in small genetically tractable animals. Here, we evaluated the utility of KCRs to suppress behavior and inhibit neural activity in Drosophila, Caenorhabditis elegans, and zebrafish. In direct comparisons with ACR1, a KCR1 variant with enhanced plasma-membrane trafficking displayed comparable potency, but with improved properties that include reduced toxicity and superior efficacy in putative high-chloride cells. This comparative analysis of behavioral inhibition between chloride- and potassium-selective silencing tools establishes KCRs as next-generation optogenetic inhibitors for in vivo circuit analysis in behaving animals.
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Affiliation(s)
- Stanislav Ott
- Program in Neuroscience and Behavioral Disorders, Duke-NUS Medical School, Singapore, Singapore
| | - Sangyu Xu
- Institute for Molecular and Cell Biology, A*STAR Agency for Science, Technology and Research, Singapore, Singapore
| | - Nicole Lee
- Program in Neuroscience and Behavioral Disorders, Duke-NUS Medical School, Singapore, Singapore
| | - Ivan Hong
- Program in Neuroscience and Behavioral Disorders, Duke-NUS Medical School, Singapore, Singapore
| | - Jonathan Anns
- Institute for Molecular and Cell Biology, A*STAR Agency for Science, Technology and Research, Singapore, Singapore
- School of Biological Sciences and Institute for Life Sciences, University of Southampton, Southampton, UK
| | - Danesha Devini Suresh
- Program in Neuroscience and Behavioral Disorders, Duke-NUS Medical School, Singapore, Singapore
| | - Zhiyi Zhang
- Program in Neuroscience and Behavioral Disorders, Duke-NUS Medical School, Singapore, Singapore
| | - Xianyuan Zhang
- Program in Neuroscience and Behavioral Disorders, Duke-NUS Medical School, Singapore, Singapore
| | - Raihanah Harion
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore
| | - Weiying Ye
- Department of Physiology, National University of Singapore, Singapore, Singapore
| | - Vaishnavi Chandramouli
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore
| | - Suresh Jesuthasan
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore
| | - Yasunori Saheki
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore
| | - Adam Claridge-Chang
- Program in Neuroscience and Behavioral Disorders, Duke-NUS Medical School, Singapore, Singapore.
- Institute for Molecular and Cell Biology, A*STAR Agency for Science, Technology and Research, Singapore, Singapore.
- Department of Physiology, National University of Singapore, Singapore, Singapore.
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3
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Van NTH, Kim WK, Nam JH. Challenges in the Therapeutic Targeting of KCa Channels: From Basic Physiology to Clinical Applications. Int J Mol Sci 2024; 25:2965. [PMID: 38474212 PMCID: PMC10932353 DOI: 10.3390/ijms25052965] [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: 12/15/2023] [Revised: 01/23/2024] [Accepted: 01/25/2024] [Indexed: 03/14/2024] Open
Abstract
Calcium-activated potassium (KCa) channels are ubiquitously expressed throughout the body and are able to regulate membrane potential and intracellular calcium concentrations, thereby playing key roles in cellular physiology and signal transmission. Consequently, it is unsurprising that KCa channels have been implicated in various diseases, making them potential targets for pharmaceutical interventions. Over the past two decades, numerous studies have been conducted to develop KCa channel-targeting drugs, including those for disorders of the central and peripheral nervous, cardiovascular, and urinary systems and for cancer. In this review, we synthesize recent findings regarding the structure and activating mechanisms of KCa channels. We also discuss the role of KCa channel modulators in therapeutic medicine. Finally, we identify the major reasons behind the delay in bringing these modulators to the pharmaceutical market and propose new strategies to promote their application.
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Affiliation(s)
- Nhung Thi Hong Van
- Department of Physiology, Dongguk University College of Medicine, Gyeongju 38066, Republic of Korea;
- Channelopathy Research Center (CRC), Dongguk University College of Medicine, Goyang 10326, Republic of Korea
| | - Woo Kyung Kim
- Channelopathy Research Center (CRC), Dongguk University College of Medicine, Goyang 10326, Republic of Korea
- Department of Internal Medicine, Graduate School of Medicine, Dongguk University, Goyang 10326, Republic of Korea
| | - Joo Hyun Nam
- Department of Physiology, Dongguk University College of Medicine, Gyeongju 38066, Republic of Korea;
- Channelopathy Research Center (CRC), Dongguk University College of Medicine, Goyang 10326, Republic of Korea
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4
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Morales J, Palmer BF. Non-steroidal mineralocorticoid antagonists and hyperkalemia monitoring in chronic kidney disease patients associated with type II diabetes: a narrative review. Postgrad Med 2024; 136:111-119. [PMID: 38344772 DOI: 10.1080/00325481.2024.2316572] [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: 01/07/2024] [Accepted: 02/05/2024] [Indexed: 02/17/2024]
Abstract
Chronic kidney disease (CKD) is a prevalent complication of Type II diabetes (T2D). The coexistence of CKD with T2D is comparable to cardiovascular disease (CVD) when the estimated glomerular filtration rate declines below 60 ml/min/1.73 m2. Screening and early detection of people with high risk for CKD would be beneficial in managing CKD progress and the associated complications such as CV complications. Renin-angiotensin-aldosterone system inhibitors (RAASi) have demonstrated beneficial effects in delaying CKD progression, but they carry the risk of hyperkalemia. Nonsteroidal mineralocorticoid antagonists (nsMRA), such as finerenone, exhibit considerable efficacy in their anti-inflammatory, antifibrotic, and renal protective effects with demonstrable reductions in CV complications. In addition, nsMRAs do not cause significant changes in serum potassium levels compared to traditional steroidal MRA. Ongoing research explores the capacity of the sodium-glucose transport protein 2 inhibitors (SGLT-2i), combined with nsMRA, to produce synergistic renal protective effects and reduce the risk of hyperkalemia. Also, a dedicated renal outcomes study (FLOW study) involving a once-weekly injectable Glucagon-like peptide-1 receptor agonist, semaglutide, was halted early by the data monitoring committee due to having achieved the predefined efficacy endpoint and considerations related to renal disease. In CKD patients with T2D on nsMRA, hyperkalemia management requires a comprehensive approach involving lifestyle adjustments, dietary modifications, regular serum potassium level monitoring, and potassium binders, if necessary. Withholding or down-titration of nsMRAs with close monitoring of serum potassium levels may be required in patients with concerning potassium levels. In light of the current state of knowledge, this review article explores the perspectives and approaches that HCPs may consider when monitoring and managing hyperkalemia in CKD patients with T2D.
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Affiliation(s)
- Javier Morales
- Medicine, Donald and Barbara Zucker School of Medicine at Hofstra Northwell, Hempstead, NY, USA
- Advanced Internal Medicine Group, P.C, East Hills, NY, USA
| | - Biff F Palmer
- Department of Internal Medicine, Division of Nephrology, University of Texas Southwestern Medical Center, Dallas, TX, USA
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5
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Talbi K, Ousingsawat J, Centeio R, Schreiber R, Kunzelmann K. KCNE1 does not shift TMEM16A from a Ca 2+ dependent to a voltage dependent Cl - channel and is not expressed in renal proximal tubule. Pflugers Arch 2023:10.1007/s00424-023-02829-5. [PMID: 37442855 PMCID: PMC10359377 DOI: 10.1007/s00424-023-02829-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Revised: 05/02/2023] [Accepted: 06/08/2023] [Indexed: 07/15/2023]
Abstract
The TMEM16A (ANO1) Cl- channel is activated by Ca2+ in a voltage-dependent manner. It is broadly expressed and was shown to be also present in renal proximal tubule (RPT). KCNQ1 is an entirely different K+ selective channel that forms the cardiac IKS potassium channel together with its ß-subunit KCNE1. Surprisingly, KCNE1 has been claimed to interact with TMEM16A, and to be required for activation of TMEM16A in mouse RPT. Interaction with KCNE1 was reported to switch TMEM16A from a Ca22+-dependent to a voltage-dependent ion channel. Here we demonstrate that KCNE1 is not expressed in mouse RPT. TMEM16A expressed in RPT is activated by angiotensin II and ATP in a KCNE1-independent manner. Coexpression of KCNE1 does not change TMEM16A to a voltage gated Cl- channel and Ca2+-dependent regulation of TMEM16A is fully maintained in the presence of KCNE1. While overexpressed KCNE1 slightly affects Ca2+-dependent regulation of TMEM16A, the data provide no evidence for KCNE1 being an auxiliary functional subunit for TMEM16A.
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Affiliation(s)
- Khaoula Talbi
- Physiological Institute, University of Regensburg, University street 31, D-93053, Regensburg, Germany
| | - Jiraporn Ousingsawat
- Physiological Institute, University of Regensburg, University street 31, D-93053, Regensburg, Germany
| | - Raquel Centeio
- Physiological Institute, University of Regensburg, University street 31, D-93053, Regensburg, Germany
| | - Rainer Schreiber
- Physiological Institute, University of Regensburg, University street 31, D-93053, Regensburg, Germany
| | - Karl Kunzelmann
- Physiological Institute, University of Regensburg, University street 31, D-93053, Regensburg, Germany.
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6
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Bioelectric regulation of intestinal stem cells. Trends Cell Biol 2022:S0962-8924(22)00234-3. [PMID: 36396487 PMCID: PMC10183058 DOI: 10.1016/j.tcb.2022.10.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Revised: 10/21/2022] [Accepted: 10/24/2022] [Indexed: 11/17/2022]
Abstract
Proper regulation of ion balance across the intestinal epithelium is essential for physiological functions, while ion imbalance causes intestinal disorders with dire health consequences. Ion channels, pumps, and exchangers are vital for regulating ion movements (i.e., bioelectric currents) that control epithelial absorption and secretion. Recent in vivo studies used the Drosophila gut to identify conserved pathways that link regulators of Ca2+, Na+ and Cl- with intestinal stem cell (ISC) proliferation. These studies laid a foundation for using the Drosophila gut to identify conserved proliferative responses triggered by bioelectric regulators. Here, we review these studies, discuss their significance, as well as the advantages of using Drosophila to unravel conserved bioelectrically induced molecular pathways in the intestinal epithelium under physiological, pathophysiological, and regenerative conditions.
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7
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Tuan VP, Yahara K, Dung HDQ, Binh TT, Huu Tung P, Tri TD, Thuan NPM, Khien VV, Trang TTH, Phuc BH, Tshibangu-Kabamba E, Matsumoto T, Akada J, Suzuki R, Okimoto T, Kodama M, Murakami K, Yano H, Fukuyo M, Takahashi N, Kato M, Nishiumi S, Azuma T, Ogura Y, Hayashi T, Toyoda A, Kobayashi I, Yamaoka Y. Genome-wide association study of gastric cancer- and duodenal ulcer-derived Helicobacter pylori strains reveals discriminatory genetic variations and novel oncoprotein candidates. Microb Genom 2021; 7. [PMID: 34846284 PMCID: PMC8743543 DOI: 10.1099/mgen.0.000680] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Genome-wide association studies (GWASs) can reveal genetic variations associated with a phenotype in the absence of any hypothesis of candidate genes. The problem of false-positive sites linked with the responsible site might be bypassed in bacteria with a high homologous recombination rate, such as Helicobacter pylori, which causes gastric cancer. We conducted a small-sample GWAS (125 gastric cancer cases and 115 controls) followed by prediction of gastric cancer and control (duodenal ulcer) H. pylori strains. We identified 11 single nucleotide polymorphisms (eight amino acid changes) and three DNA motifs that, combined, allowed effective disease discrimination. They were often informative of the underlying molecular mechanisms, such as electric charge alteration at the ligand-binding pocket, alteration in subunit interaction, and mode-switching of DNA methylation. We also identified three novel virulence factors/oncoprotein candidates. These results provide both defined targets for further informatic and experimental analyses to gain insights into gastric cancer pathogenesis and a basis for identifying a set of biomarkers for distinguishing these H. pylori-related diseases.
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Affiliation(s)
- Vo Phuoc Tuan
- Department of Endoscopy, Cho Ray Hospital, Ho Chi Minh, Vietnam
- Department of Environmental and Preventive Medicine, Oita University Faculty of Medicine, Oita, Japan
| | - Koji Yahara
- Antimicrobial Resistance ResearchCenter, National Institute of Infectious Diseases, Tokyo, Japan
- *Correspondence: Koji Yahara,
| | | | - Tran Thanh Binh
- Department of Endoscopy, Cho Ray Hospital, Ho Chi Minh, Vietnam
| | - Pham Huu Tung
- Department of Endoscopy, Cho Ray Hospital, Ho Chi Minh, Vietnam
| | - Tran Dinh Tri
- Department of Endoscopy, Cho Ray Hospital, Ho Chi Minh, Vietnam
| | | | - Vu Van Khien
- Department of GI Endoscopy, 108 Central Hospital, Hanoi, Vietnam
| | | | - Bui Hoang Phuc
- Department of Environmental and Preventive Medicine, Oita University Faculty of Medicine, Oita, Japan
- Department of Microbiology, Cho Ray Hospital, Ho Chi Minh, Vietnam
| | | | - Takashi Matsumoto
- Department of Environmental and Preventive Medicine, Oita University Faculty of Medicine, Oita, Japan
| | - Junko Akada
- Department of Environmental and Preventive Medicine, Oita University Faculty of Medicine, Oita, Japan
| | - Rumiko Suzuki
- Department of Environmental and Preventive Medicine, Oita University Faculty of Medicine, Oita, Japan
| | - Tadayoshi Okimoto
- Department of Gastroenterology, Oita University Faculty of Medicine, Yufu, Oita, Japan
| | - Masaaki Kodama
- Department of Gastroenterology, Oita University Faculty of Medicine, Yufu, Oita, Japan
| | - Kazunari Murakami
- Department of Gastroenterology, Oita University Faculty of Medicine, Yufu, Oita, Japan
| | - Hirokazu Yano
- Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, University of Tokyo, Tokyo, Japan
- Institute of Medical Science, University of Tokyo, Tokyo, Japan
- Graduate School of Life Sciences, Tohoku University, Sendai, Japan
| | - Masaki Fukuyo
- Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, University of Tokyo, Tokyo, Japan
- Institute of Medical Science, University of Tokyo, Tokyo, Japan
- Department of Molecular Oncology, Chiba University, Chiba, Japan
| | - Noriko Takahashi
- Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, University of Tokyo, Tokyo, Japan
- Institute of Medical Science, University of Tokyo, Tokyo, Japan
- Department of Infectious Diseases, Kyorin University School of Medicine, Mitaka City, Tokyo, Japan
| | - Mototsugu Kato
- Division of Endoscopy, Hokkaido University Hospital, Sapporo, Hokkaido, Japan
- Department of Gastroenterology, National Hospital Organization Hakodate Hospital, Hakodate, Hokkaido, Japan
| | - Shin Nishiumi
- Department of Gastroenterology, Graduate School of Medicine, Kobe University, Chuou-ku, Kobe, Hyogo, Japan
- Department of Omics Medicine, Hyogo College of Medicine, Hyogo, Japan
| | - Takashi Azuma
- Department of Gastroenterology, Graduate School of Medicine, Kobe University, Chuou-ku, Kobe, Hyogo, Japan
| | - Yoshitoshi Ogura
- Department of Bacteriology, Faculty of Medical Sciences, Kyushu University, Fukuoka, Japan
- Division of Microbiology, Department of Infectious Medicine, Kurume University School of Medicine, Kurume, Fukuoka, Japan
| | - Tetsuya Hayashi
- Department of Bacteriology, Faculty of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Atsushi Toyoda
- Advanced GenomicsCenter, National Institute of Genetics, Shizuoka, Japan
| | - Ichizo Kobayashi
- Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, University of Tokyo, Tokyo, Japan
- Institute of Medical Science, University of Tokyo, Tokyo, Japan
- Department of Infectious Diseases, Kyorin University School of Medicine, Mitaka City, Tokyo, Japan
- Research Center for Micro-Nano Technology, Hosei University, Tokyo, Japan
- *Correspondence: Ichizo Kobayashi, ;
| | - Yoshio Yamaoka
- Department of Environmental and Preventive Medicine, Oita University Faculty of Medicine, Oita, Japan
- Department of Medicine, gastroenterology section, Baylor College of Medicine, Houston TX, USA
- *Correspondence: Yoshio Yamaoka,
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8
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Yip JL, Balasuriya GK, Spencer SJ, Hill-Yardin EL. The Role of Intestinal Macrophages in Gastrointestinal Homeostasis: Heterogeneity and Implications in Disease. Cell Mol Gastroenterol Hepatol 2021; 12:1701-1718. [PMID: 34506953 PMCID: PMC8551786 DOI: 10.1016/j.jcmgh.2021.08.021] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Revised: 08/29/2021] [Accepted: 08/30/2021] [Indexed: 12/13/2022]
Abstract
Intestinal macrophages play a key role in the gut immune system and the regulation of gastrointestinal physiology, including gut motility and secretion. Their ability to keep the gut from chronic inflammation despite constantly facing foreign antigens has been an important focus in gastrointestinal research. However, the heterogeneity of intestinal macrophages has impeded our understanding of their specific roles. It is now becoming clear that subsets of intestinal macrophages play diverse roles in various gastrointestinal diseases. This occurs through a complex interplay between cytokine production and enteric nervous system activation that differs for each pathologic condition. Key diseases and disorders in which intestinal macrophages play a role include postoperative ileus, inflammatory bowel disease, necrotizing enterocolitis, as well as gastrointestinal disorders associated with human immunodeficiency virus and Parkinson's disease. Here, we review the identification of intestinal macrophage subsets based on their origins and functions, how specific subsets regulate gut physiology, and the potential for these heterogeneous subpopulations to contribute to disease states. Furthermore, we outline the potential for these subpopulations to provide unique targets for the development of novel therapies for these disorders.
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Affiliation(s)
| | | | - Sarah J. Spencer
- School of Health and Biomedical Sciences,Australian Research Council Centre of Excellence for Nanoscale Biophotonics, Royal Melbourne Instutite of Technology, Melbourne, Victoria, Australia
| | - Elisa L. Hill-Yardin
- School of Health and Biomedical Sciences,Correspondence Address correspondence to: Elisa L. Hill-Yardin, PhD, School of Health and Biomedical Sciences, RMIT University, Melbourne, Victoria 3083, Australia.
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9
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Chen J, Zhang M, Ma Z, Yuan D, Zhu J, Tuo B, Li T, Liu X. Alteration and dysfunction of ion channels/transporters in a hypoxic microenvironment results in the development and progression of gastric cancer. Cell Oncol (Dordr) 2021; 44:739-749. [PMID: 33856653 PMCID: PMC8338819 DOI: 10.1007/s13402-021-00604-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/19/2021] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Gastric cancer (GC) is one of the most common malignant cancers in the world and has only few treatment options and, concomitantly, a poor prognosis. It is generally accepted now that the tumor microenvironment, particularly that under hypoxia, plays an important role in cancer development. Hypoxia can regulate the energy metabolism and malignancy of tumor cells by inducing or altering various important factors, such as oxidative stress, reactive oxygen species (ROS), hypoxia-inducible factors (HIFs), autophagy and acidosis. In addition, altered expression and/or dysfunction of ion channels/transporters (ICTs) have been encountered in a variety of human tumors, including GC, and to play an important role in the processes of tumor cell proliferation, migration, invasion and apoptosis. Increasing evidence indicates that ICTs are at least partly involved in interactions between cancer cells and their hypoxic microenvironment. Here, we provide an overview of the different ICTs that regulate or are regulated by hypoxia in GC. CONCLUSIONS AND PERSPECTIVES Hypoxia is one of the major obstacles to cancer therapy. Regulating cellular responses and factors under hypoxia can inhibit GC. Similarly, altering the expression or activity of ICTs, such as the application of ion channel inhibitors, can slow down the growth and/or migration of GC cells. Since targeting the hypoxic microenvironment and/or ICTs may be a promising strategy for the treatment of GC, more attention should be paid to the interplay between ICTs and the development and progression of GC in such a microenvironment.
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Affiliation(s)
- Junling Chen
- Department of Gastroenterology, Affiliated Hospital of Zunyi Medical University, Zunyi, 563003, Guizhou Province, China
- Digestive Disease Institute of Guizhou Province, Zunyi, Guizhou Province, China
| | - Minglin Zhang
- Department of Gastroenterology, Affiliated Hospital of Zunyi Medical University, Zunyi, 563003, Guizhou Province, China
- Digestive Disease Institute of Guizhou Province, Zunyi, Guizhou Province, China
| | - Zhiyuan Ma
- Department of Gastroenterology, Affiliated Hospital of Zunyi Medical University, Zunyi, 563003, Guizhou Province, China
- Digestive Disease Institute of Guizhou Province, Zunyi, Guizhou Province, China
- Department of Thyroid and Breast Surgery, Affiliated Hospital of Zunyi Medical University, Zunyi, 563003, Guizhou Province, China
| | - Dumin Yuan
- Department of Gastroenterology, Affiliated Hospital of Zunyi Medical University, Zunyi, 563003, Guizhou Province, China
- Digestive Disease Institute of Guizhou Province, Zunyi, Guizhou Province, China
| | - Jiaxing Zhu
- Department of Gastroenterology, Affiliated Hospital of Zunyi Medical University, Zunyi, 563003, Guizhou Province, China
- Digestive Disease Institute of Guizhou Province, Zunyi, Guizhou Province, China
| | - Biguang Tuo
- Department of Gastroenterology, Affiliated Hospital of Zunyi Medical University, Zunyi, 563003, Guizhou Province, China
- Digestive Disease Institute of Guizhou Province, Zunyi, Guizhou Province, China
| | - Taolang Li
- Department of Thyroid and Breast Surgery, Affiliated Hospital of Zunyi Medical University, Zunyi, 563003, Guizhou Province, China.
| | - Xuemei Liu
- Department of Gastroenterology, Affiliated Hospital of Zunyi Medical University, Zunyi, 563003, Guizhou Province, China.
- Digestive Disease Institute of Guizhou Province, Zunyi, Guizhou Province, China.
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10
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Goswami S. Interplay of potassium channel, gastric parietal cell and proton pump in gastrointestinal physiology, pathology and pharmacology. Minerva Gastroenterol (Torino) 2021; 68:289-305. [PMID: 34309336 DOI: 10.23736/s2724-5985.21.02964-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Gastric acid secretion plays a pivotal role in the physiology of gastrointestinal tract. The functioning of the system encompasses a P2 ATPase pump (which shuttles electroneutral function at low pH) along with different voltage sensitive/neutral ion channels, cytosolic proteins, acid sensor receptors as well hormonal regulators. The increased acid secretion is a pathological marker of several diseases like peptic ulcer, gastroesophageal reflux disease (GERD), chronic gastritis, and the bug Helicobacter pylori (H. pylori) has also a critical role, which altogether affects the patient's quality of life. This review comprehensively describes about the nature of potassium ion channel and its mediators, the different clinical strategy to control acid rebound, and some basic experimental observations performed to study the interplay of ion channels, pumps, as well as mediators during acid secretion. Different aspects of regulation of gastric acid secretion have been focused either in terms of physiology of secretion or molecular interactions. The importance of H pylori infection and its treatment have also been discussed. Furthermore, the relevance of calcium signaling during acid secretion has been reviewed. The entire theme will make anyone to understand in details about the gastric secretion machinery in general.
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Affiliation(s)
- Suchandra Goswami
- Smt. Vidyawati College of Pharmacy, Gora Machhiya, Jhansi, Uttar Pradesh, India -
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11
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Goblet cell LRRC26 regulates BK channel activation and protects against colitis in mice. Proc Natl Acad Sci U S A 2021; 118:2019149118. [PMID: 33431687 DOI: 10.1073/pnas.2019149118] [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] [Indexed: 12/17/2022] Open
Abstract
Goblet cells (GCs) are specialized cells of the intestinal epithelium contributing critically to mucosal homeostasis. One of the functions of GCs is to produce and secrete MUC2, the mucin that forms the scaffold of the intestinal mucus layer coating the epithelium and separates the luminal pathogens and commensal microbiota from the host tissues. Although a variety of ion channels and transporters are thought to impact on MUC2 secretion, the specific cellular mechanisms that regulate GC function remain incompletely understood. Previously, we demonstrated that leucine-rich repeat-containing protein 26 (LRRC26), a known regulatory subunit of the Ca2+-and voltage-activated K+ channel (BK channel), localizes specifically to secretory cells within the intestinal tract. Here, utilizing a mouse model in which MUC2 is fluorescently tagged, thereby allowing visualization of single GCs in intact colonic crypts, we show that murine colonic GCs have functional LRRC26-associated BK channels. In the absence of LRRC26, BK channels are present in GCs, but are not activated at physiological conditions. In contrast, all tested MUC2- cells completely lacked BK channels. Moreover, LRRC26-associated BK channels underlie the BK channel contribution to the resting transepithelial current across mouse distal colonic mucosa. Genetic ablation of either LRRC26 or BK pore-forming α-subunit in mice results in a dramatically enhanced susceptibility to colitis induced by dextran sodium sulfate. These results demonstrate that normal potassium flux through LRRC26-associated BK channels in GCs has protective effects against colitis in mice.
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12
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Nickerson AJ, Rajendran VM. Aldosterone up-regulates basolateral Na + -K + -2Cl - cotransporter-1 to support enhanced large-conductance K + channel-mediated K + secretion in rat distal colon. FASEB J 2021; 35:e21606. [PMID: 33908679 PMCID: PMC9777186 DOI: 10.1096/fj.202100203r] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Revised: 03/24/2021] [Accepted: 04/05/2021] [Indexed: 12/25/2022]
Abstract
Na+ -K+ -2Cl- cotransporter-1 (NKCC1) facilitates basolateral K+ and Cl- uptake, supporting their efflux across mucosal membranes of colonic epithelial cells. NKCC1 activity has also been shown to be critical for electrogenic K+ secretion induced by aldosterone, which is known to stimulate large-conductance K+ (BK) channel expression in mucosal membranes. This study was aimed to (1) identify whether aldosterone enhances NKCC1 expression specifically to support BK-mediated K+ secretion and (2) to determine whether increased NKCC1 supports electrogenic Cl- secretion in parallel to K+ secretion. Dietary Na+ depletion was used to induce secondary hyperaldosteronism in rats, or aldosterone was administered ex vivo to rat distal colonic mucosae. NKCC1-dependent electrogenic K+ or Cl- secretion was measured as a function of short circuit current (ISC ). qRT-PCR, western blot, and immunofluorescence analyses were performed using standard techniques. Aldosterone enhanced NKCC1 and BKα expression and electrogenic K+ secretion in the distal colon, which was inhibited by either serosal bumetanide (NKCC1 inhibitor) or mucosal iberiotoxin (IbTX; BK channel blocker), but not TRAM-34 (IK channel blocker). Expression of NKCC1 and BKα proteins was enhanced in crypt cells of hyper-aldosterone rats. However, neither NKCC1-dependent Cl- secretion nor CFTR (apical Cl- channel) expression was enhanced by aldosterone. We conclude that aldosterone enhances NKCC1 to support BK-mediated K+ secretion independently of Cl- secretion in the distal colon. The regulation of NKCC1 expression/K+ secretion by aldosterone may be a therapeutic target in treating gastrointestinal disorders associated with alterations in colonic K+ transport, such as colonic pseudo-obstruction, and hyperkalemia associated with renal disease.
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Affiliation(s)
- Andrew J. Nickerson
- Department of Physiology, Pharmacology and Neuroscience, West Virginia University School of Medicine, Morgantown, West Virginia
| | - Vazhaikkurichi M. Rajendran
- Department of Biochemistry, West Virginia University School of Medicine, Morgantown, West Virginia,Departments of Medicine, West Virginia University School of Medicine, Morgantown, West Virginia
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13
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Cosme D, Estevinho MM, Rieder F, Magro F. Potassium channels in intestinal epithelial cells and their pharmacological modulation: a systematic review. Am J Physiol Cell Physiol 2020; 320:C520-C546. [PMID: 33326312 DOI: 10.1152/ajpcell.00393.2020] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Several potassium channels (KCs) have been described throughout the gastrointestinal tract. Notwithstanding, their contribution to both physiologic and pathophysiologic conditions, as inflammatory bowel disease (IBD), remains underexplored. Therefore, we aim to systematically review, for the first time, the evidence on the characteristics and modulation of KCs in intestinal epithelial cells (IECs). PubMed, Scopus, and Web of Science were searched to identify studies focusing on KCs and their modulation in IECs. The included studies were assessed using a reporting inclusiveness checklist. From the 745 identified records, 73 met the inclusion criteria; their reporting inclusiveness was moderate-high. Some studies described the physiological role of KCs, while others explored their importance in pathological settings. Globally, in IBD animal models, apical KCa1.1 channels, responsible for luminal secretion, were upregulated. In human colonocytes, basolateral KCa3.1 channels were downregulated. The pharmacological inhibition of K2P and Kv influenced intestinal barrier function, promoting inflammation. Evidence suggests a strong association between KCs expression and secretory mechanisms in human and animal IECs. Further research is warranted to explore the usefulness of KC pharmacological modulation as a therapeutic target.
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Affiliation(s)
- Dina Cosme
- Department of Biomedicine, Unit of Pharmacology and Therapeutics, Faculty of Medicine, University of Porto, Porto, Portugal.,MedInUP, Center for Drug Discovery and Innovative Medicines, Porto, Portugal
| | - Maria Manuela Estevinho
- Department of Biomedicine, Unit of Pharmacology and Therapeutics, Faculty of Medicine, University of Porto, Porto, Portugal.,Department of Gastroenterology, Centro Hospitalar Vila Nova de Gaia/Espinho, Vila Nova de Gaia, Portugal
| | - Florian Rieder
- Department of Gastroenterology, Hepatology and Nutrition, Digestive Diseases, and Surgery Institute, Cleveland Clinic Foundation, Cleveland, Ohio.,Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, Ohio
| | - Fernando Magro
- Department of Biomedicine, Unit of Pharmacology and Therapeutics, Faculty of Medicine, University of Porto, Porto, Portugal.,MedInUP, Center for Drug Discovery and Innovative Medicines, Porto, Portugal.,Department of Gastroenterology, Centro Hospitalar São João, Porto, Portugal
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14
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Potier-Cartereau M, Raoul W, Weber G, Mahéo K, Rapetti-Mauss R, Gueguinou M, Buscaglia P, Goupille C, Le Goux N, Abdoul-Azize S, Lecomte T, Fromont G, Chantome A, Mignen O, Soriani O, Vandier C. Potassium and Calcium Channel Complexes as Novel Targets for Cancer Research. Rev Physiol Biochem Pharmacol 2020; 183:157-176. [PMID: 32767122 DOI: 10.1007/112_2020_24] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The intracellular Ca2+ concentration is mainly controlled by Ca2+ channels. These channels form complexes with K+ channels, which function to amplify Ca2+ flux. In cancer cells, voltage-gated/voltage-dependent Ca2+ channels and non-voltage-gated/voltage-independent Ca2+ channels have been reported to interact with K+ channels such as Ca2+-activated K+ channels and voltage-gated K+ channels. These channels are activated by an increase in cytosolic Ca2+ concentration or by membrane depolarization, which induces membrane hyperpolarization, increasing the driving force for Ca2+ flux. These complexes, composed of K+ and Ca2+ channels, are regulated by several molecules including lipids (ether lipids and cholesterol), proteins (e.g. STIM), receptors (e.g. S1R/SIGMAR1), and peptides (e.g. LL-37) and can be targeted by monoclonal antibodies, making them novel targets for cancer research.
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Affiliation(s)
| | - William Raoul
- N2C UMR 1069, University of Tours, INSERM, Tours, France
| | - Gunther Weber
- N2C UMR 1069, University of Tours, INSERM, Tours, France
| | - Karine Mahéo
- N2C UMR 1069, University of Tours, INSERM, Tours, France
| | | | | | - Paul Buscaglia
- LBAI UMR 1227, University of Brest, INSERM, Brest, France
| | - Caroline Goupille
- N2C UMR 1069, University of Tours, INSERM, CHRU de Tours, Tours, France
| | - Nelig Le Goux
- LBAI UMR 1227, University of Brest, INSERM, Brest, France
| | | | - Thierry Lecomte
- EA 7501 GICC, University of Tours, CHRU de Tours, Department of Hepato-Gastroenterology and Digestive Oncology, Tours, France
| | - Gaëlle Fromont
- N2C UMR 1069, University of Tours, INSERM, CHRU de Tours, Department of Pathology, Tours, France
| | | | - Olivier Mignen
- LBAI UMR 1227, University of Brest, INSERM, Brest, France
| | - Olivier Soriani
- iBV, INSERM, CNRS, University of the Côte d'Azur, Nice, France
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15
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Becskeházi E, Korsós MM, Erőss B, Hegyi P, Venglovecz V. OEsophageal Ion Transport Mechanisms and Significance Under Pathological Conditions. Front Physiol 2020; 11:855. [PMID: 32765303 PMCID: PMC7379034 DOI: 10.3389/fphys.2020.00855] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Accepted: 06/25/2020] [Indexed: 12/20/2022] Open
Abstract
Ion transporters play an important role in several physiological functions, such as cell volume regulation, pH homeostasis and secretion. In the oesophagus, ion transport proteins are part of the epithelial resistance, a mechanism which protects the oesophagus against reflux-induced damage. A change in the function or expression of ion transporters has significance in the development or neoplastic progression of Barrett’s oesophagus (BO). In this review, we discuss the physiological and pathophysiological roles of ion transporters in the oesophagus, highlighting transport proteins which serve as therapeutic targets or prognostic markers in eosinophilic oesophagitis, BO and esophageal cancer. We believe that this review highlights important relationships which might contribute to a better understanding of the pathomechanisms of esophageal diseases.
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Affiliation(s)
- Eszter Becskeházi
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
| | | | - Bálint Erőss
- Institute for Translational Medicine, Szentágothai Research Centre, Medical School, University of Pécs, Pécs, Hungary
| | - Péter Hegyi
- Institute for Translational Medicine, Szentágothai Research Centre, Medical School, University of Pécs, Pécs, Hungary.,Division of Gastroenterology, First Department of Medicine, Medical School, University of Pécs, Pécs, Hungary.,First Department of Medicine, University of Szeged, Szeged, Hungary
| | - Viktória Venglovecz
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
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16
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Manfroni G, Ragonese F, Monarca L, Astolfi A, Mancinelli L, Iannitti RG, Bastioli F, Barreca ML, Cecchetti V, Fioretti B. New Insights on KCa3.1 Channel Modulation. Curr Pharm Des 2020; 26:2096-2101. [PMID: 32175839 DOI: 10.2174/1381612826666200316152645] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Accepted: 03/11/2020] [Indexed: 11/22/2022]
Abstract
The human intermediate conductance calcium-activated potassium channel, KCa3.1, is involved in several pathophysiological conditions playing a critical role in cell secretory machinery and calcium signalling. The recent cryo-EM analysis provides new insights for understanding the modulation by both endogenous and pharmacological agents. A typical feature of this channel is the low open probability in saturating calcium concentrations and its modulation by potassium channel openers (KCOs), such as benzo imidazolone 1-EBIO, without changing calcium-dependent activation. In this paper, we proposed a model of KCOs action in the modulation of channel activity. The KCa3.1 channel has a very rich pharmacological profile with several classes of molecules that selectively interact with different binding sites of the channel. Among them, benzo imidazolones can be openers (positive modulators such as 1-EBIO, DC-EBIO) or blockers (negative modulators such as NS1619). Through computation modelling techniques, we identified the 1,4-benzothiazin-3-one as a promising scaffold to develop new KCa3.1 channel modulators. Further studies are needed to explore the potential use of 1-4 benzothiazine- 3-one in KCa3.1 modulation and its pharmacological application.
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Affiliation(s)
- Giuseppe Manfroni
- Department of Pharmaceutical Sciences, University of Perugia, Via del Liceo, 1-06123-Perugia (PG), Italy
| | - Francesco Ragonese
- Department of Chemistry, Biology and Biotechnologies, University of Perugia, Via Elce di Sotto 8, 06123 Perugia, Italy.,Department of Experimental Medicine, Perugia Medical School, University of Perugia, Piazza Lucio Severi 1, 06132 Perugia, Italy
| | - Lorenzo Monarca
- Department of Chemistry, Biology and Biotechnologies, University of Perugia, Via Elce di Sotto 8, 06123 Perugia, Italy.,Department of Experimental Medicine, Perugia Medical School, University of Perugia, Piazza Lucio Severi 1, 06132 Perugia, Italy
| | - Andrea Astolfi
- Department of Pharmaceutical Sciences, University of Perugia, Via del Liceo, 1-06123-Perugia (PG), Italy
| | - Loretta Mancinelli
- Department of Chemistry, Biology and Biotechnologies, University of Perugia, Via Elce di Sotto 8, 06123 Perugia, Italy
| | | | | | - Maria L Barreca
- Department of Pharmaceutical Sciences, University of Perugia, Via del Liceo, 1-06123-Perugia (PG), Italy
| | - Violetta Cecchetti
- Department of Pharmaceutical Sciences, University of Perugia, Via del Liceo, 1-06123-Perugia (PG), Italy
| | - Bernard Fioretti
- Department of Chemistry, Biology and Biotechnologies, University of Perugia, Via Elce di Sotto 8, 06123 Perugia, Italy
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17
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Parathyroid hormone increases CFTR expression and function in Caco-2 intestinal epithelial cells. Biochem Biophys Res Commun 2020; 523:816-821. [DOI: 10.1016/j.bbrc.2019.12.106] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Accepted: 12/31/2019] [Indexed: 12/29/2022]
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18
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Proquin H, Jonkhout MCM, Jetten MJ, van Loveren H, de Kok TM, Briedé JJ. Transcriptome changes in undifferentiated Caco-2 cells exposed to food-grade titanium dioxide (E171): contribution of the nano- and micro- sized particles. Sci Rep 2019; 9:18287. [PMID: 31797963 PMCID: PMC6893026 DOI: 10.1038/s41598-019-54675-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Accepted: 11/14/2019] [Indexed: 12/14/2022] Open
Abstract
The food additive titanium dioxide (TiO2), or E171, is a white food colorant. Recent studies showed after E171 ingestion a significantly increased number of colorectal tumours in a colorectal cancer mouse model as well as inflammatory responses and dysregulation of the immune system in the intestine of rats. In the mouse colon, E171 induced gene expression changes related to oxidative stress, impairment of the immune system, activation of signalling and cancer-related processes. E171 comprises nanoparticles (NPs) and microparticles (MPs). Previous in vitro studies showed that E171, NPs and MPs induced oxidative stress responses, DNA damage and micronuclei formation. This study aimed to investigate the relative contribution of the NPs and MPs to effects of E171 at the transcriptome level in undifferentiated Caco-2 cells by genome wide microarray analysis. The results showed that E171, NPs, and MPs induce gene expression changes related to signalling, inflammation, immune system, transport and cancer. At the pathway level, metabolism of proteins with the insulin processing pathway and haemostasis were specific to E171 exposure. The gene expression changes associated with the immune system and inflammation induced by E171, MPs, and NPs suggest the creation of a favourable environment for colon cancer development.
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Affiliation(s)
- Héloïse Proquin
- Department of Toxicogenomics, GROW institute of Oncology and Developmental Biology, Maastricht University, P.O. Box 616, 6200, MD, Maastricht, the Netherlands
| | - Marloes C M Jonkhout
- Department of Cellular and Molecular Medicine, KU Leuven, Herestraat 49, box 901 3000, Leuven, Belgium
| | - Marlon J Jetten
- Complex Tissue Regeneration (CTR), Institute for Technology-Inspired Regenerative Medicine (MERLN), Maastricht University, P.O. Box 616, 6200, MD, Maastricht, the Netherlands
| | - Henk van Loveren
- Department of Toxicogenomics, GROW institute of Oncology and Developmental Biology, Maastricht University, P.O. Box 616, 6200, MD, Maastricht, the Netherlands
| | - Theo M de Kok
- Department of Toxicogenomics, GROW institute of Oncology and Developmental Biology, Maastricht University, P.O. Box 616, 6200, MD, Maastricht, the Netherlands
| | - Jacob J Briedé
- Department of Toxicogenomics, GROW institute of Oncology and Developmental Biology, Maastricht University, P.O. Box 616, 6200, MD, Maastricht, the Netherlands.
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19
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Brown BM, Shim H, Christophersen P, Wulff H. Pharmacology of Small- and Intermediate-Conductance Calcium-Activated Potassium Channels. Annu Rev Pharmacol Toxicol 2019; 60:219-240. [PMID: 31337271 DOI: 10.1146/annurev-pharmtox-010919-023420] [Citation(s) in RCA: 65] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The three small-conductance calcium-activated potassium (KCa2) channels and the related intermediate-conductance KCa3.1 channel are voltage-independent K+ channels that mediate calcium-induced membrane hyperpolarization. When intracellular calcium increases in the channel vicinity, it calcifies the flexible N lobe of the channel-bound calmodulin, which then swings over to the S4-S5 linker and opens the channel. KCa2 and KCa3.1 channels are highly druggable and offer multiple binding sites for venom peptides and small-molecule blockers as well as for positive- and negative-gating modulators. In this review, we briefly summarize the physiological role of KCa channels and then discuss the pharmacophores and the mechanism of action of the most commonly used peptidic and small-molecule KCa2 and KCa3.1 modulators. Finally, we describe the progress that has been made in advancing KCa3.1 blockers and KCa2.2 negative- and positive-gating modulators toward the clinic for neurological and cardiovascular diseases and discuss the remaining challenges.
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Affiliation(s)
- Brandon M Brown
- Department of Pharmacology, University of California, Davis, California 95616, USA;
| | - Heesung Shim
- Department of Pharmacology, University of California, Davis, California 95616, USA;
| | | | - Heike Wulff
- Department of Pharmacology, University of California, Davis, California 95616, USA;
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20
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Du C, Chen S, Wan H, Chen L, Li L, Guo H, Tuo B, Dong H. Different functional roles for K + channel subtypes in regulating small intestinal glucose and ion transport. Biol Open 2019; 8:bio.042200. [PMID: 31243019 PMCID: PMC6679390 DOI: 10.1242/bio.042200] [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] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Although K+ channels are important in mediating the driving force for colonic ion transport, their role in small intestinal transport is poorly understood. To investigate this, small intestinal short circuit currents (Isc ) and HCO3 - secretion were measured in mice, and intracellular pH (pHi) was measured in small intestinal epithelial SCBN cells. The expression and location of Kv subtypes were verified by RT-PCR, western blotting and immunohistochemistry. Diabetic mice were also used to investigate the role of Kv subtypes in regulating intestinal glucose absorption. We found that KV7.1 is not involved in duodenal ion transport, while KCa3.1 selectively regulates duodenal Isc and HCO3 - secretion in a Ca2+-mediated but not cAMP-mediated manner. Blockade of KCa3.1 increased the rate of HCO3 - fluxes via cystic fibrosis transmembrane conductance regulator (CFTR) channels in SCBN cells. Jejunal Isc was significantly stimulated by glucose, but markedly inhibited by 4-aminopyridine (4-AP) and tetraethylammonium (TEA). Moreover, both Kv1.1 and Kv1.3 were expressed in jejunal mucosae. Finally, 4-AP significantly attenuated weight gain of normal and diabetic mice, and both 4-AP and TEA significantly lowered blood glucose of diabetic mice. This study not only examines the contribution of various K+ channel subtypes to small intestinal epithelial ion transport and glucose absorption, but also proposes a novel concept for developing specific K+ channel blockers to reduce weight gain and lower blood glucose in diabetes mellitus.
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Affiliation(s)
- Chao Du
- Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China.,Department of Gastroenterology and Hepatology, Chengdu Military General Hospital, Sichuan Province, Chengdu 610000, China
| | - Siyuan Chen
- 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
| | - Lihong Chen
- Department of Gastroenterology, Affiliated Hospital, Zunyi Medical College, and Digestive Disease Institute of Guizhou Province, Zunyi 563003, China
| | - Lingyu Li
- Department of Gastroenterology, Affiliated Hospital, Zunyi Medical College, and Digestive Disease Institute of Guizhou Province, Zunyi 563003, China
| | - Hong Guo
- Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China
| | - Biguang Tuo
- 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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Rao MC. Physiology of Electrolyte Transport in the Gut: Implications for Disease. Compr Physiol 2019; 9:947-1023. [PMID: 31187895 DOI: 10.1002/cphy.c180011] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
We now have an increased understanding of the genetics, cell biology, and physiology of electrolyte transport processes in the mammalian intestine, due to the availability of sophisticated methodologies ranging from genome wide association studies to CRISPR-CAS technology, stem cell-derived organoids, 3D microscopy, electron cryomicroscopy, single cell RNA sequencing, transgenic methodologies, and tools to manipulate cellular processes at a molecular level. This knowledge has simultaneously underscored the complexity of biological systems and the interdependence of multiple regulatory systems. In addition to the plethora of mammalian neurohumoral factors and their cross talk, advances in pyrosequencing and metagenomic analyses have highlighted the relevance of the microbiome to intestinal regulation. This article provides an overview of our current understanding of electrolyte transport processes in the small and large intestine, their regulation in health and how dysregulation at multiple levels can result in disease. Intestinal electrolyte transport is a balance of ion secretory and ion absorptive processes, all exquisitely dependent on the basolateral Na+ /K+ ATPase; when this balance goes awry, it can result in diarrhea or in constipation. The key transporters involved in secretion are the apical membrane Cl- channels and the basolateral Na+ -K+ -2Cl- cotransporter, NKCC1 and K+ channels. Absorption chiefly involves apical membrane Na+ /H+ exchangers and Cl- /HCO3 - exchangers in the small intestine and proximal colon and Na+ channels in the distal colon. Key examples of our current understanding of infectious, inflammatory, and genetic diarrheal diseases and of constipation are provided. © 2019 American Physiological Society. Compr Physiol 9:947-1023, 2019.
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Affiliation(s)
- Mrinalini C Rao
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, Illinois, USA
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22
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Menezes CJ, Worcester EM, Coe FL, Asplin J, Bergsland KJ, Ko B. Mechanisms for falling urine pH with age in stone formers. Am J Physiol Renal Physiol 2019; 317:F65-F72. [PMID: 31017011 DOI: 10.1152/ajprenal.00066.2019] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
One of the main functions of the kidney is to excrete an acid load derived from both dietary and endogenous sources, thus maintaining the pH of other fluids in the body. Urine pH is also of particular interest in stone formers, since it determines the presence of either calcium phosphate or uric acid content in stones. Others have noted in epidemiological studies a rise in incidence of low pH-dependent uric acid stones with age, coinciding with a decrease in the incidence of high pH-dependent phosphate stones. Taken together, these trends are suggestive of a longitudinal decline in urine pH in stone-forming patients, and, if true, this could explain the observed trends in stone incidence. We studied 7,891 stone formers, all of whom collected a 24-h urine sample and matching serum. Multivariate modeling revealed that urine pH did indeed fall with age and particularly between the ages of 20 and 50 yr old in both men and women. We sought to explain this trend through the inclusion of traditionally understood determinants of urine pH such as urinary buffers, estimates of glomerular filtration, and dietary acid load, but these, taken together, accounted for but a small fraction of the pH fall. Gastrointestinal anion absorption was the strongest predictor of urine pH in all age groups, as we have previously reported in middle-aged normal men and women. However, we found that, despite a decreasing urine pH, gastrointestinal anion absorption increased monotonically with age. In fact, after adjustment for gastrointestinal anion absorption, urine pH declined more markedly, suggesting that bicarbonate-producing anion absorption is regulated in a manner that offsets the decline of urine pH.
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Affiliation(s)
- Cameron J Menezes
- Department of Medicine, University of Chicago Medicine , Chicago, Illinois
| | - Elaine M Worcester
- Department of Medicine, University of Chicago Medicine , Chicago, Illinois
| | - Fredric L Coe
- Department of Medicine, University of Chicago Medicine , Chicago, Illinois
| | - John Asplin
- Litholink, Laboratory Corporation of America Holdings , Chicago, Illinois
| | | | - Benjamin Ko
- Department of Medicine, University of Chicago Medicine , Chicago, Illinois
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23
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Duan T, Cil O, Thiagarajah JR, Verkman AS. Intestinal epithelial potassium channels and CFTR chloride channels activated in ErbB tyrosine kinase inhibitor diarrhea. JCI Insight 2019; 4:126444. [PMID: 30668547 PMCID: PMC6478423 DOI: 10.1172/jci.insight.126444] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Accepted: 01/14/2019] [Indexed: 12/11/2022] Open
Abstract
Diarrhea is a major side effect of ErbB receptor tyrosine kinase inhibitors (TKIs) in cancer chemotherapy. Here, we show that the primary mechanism of ErbB TKI diarrhea is activation of basolateral membrane potassium (K+) channels and apical membrane chloride (Cl-) channels in intestinal epithelia and demonstrate the efficacy of channel blockers in a rat model of TKI diarrhea. Short-circuit current in colonic epithelial cells showed that the TKIs gefitinib, lapatinib, and afatinib do not affect basal secretion but amplify carbachol-stimulated secretion by 2- to 3-fold. Mechanistic studies with the second-generation TKI afatinib showed that the amplifying effect on Cl- secretion was Ca2+ and cAMP independent, was blocked by CF transmembrane conductance regulator (CFTR) and K+ channel inhibitors, and involved EGFR binding and ERK signaling. Afatinib-amplified activation of basolateral K+ and apical Cl- channels was demonstrated by selective membrane permeabilization, ion substitution, and channel inhibitors. Rats that were administered afatinib orally at 60 mg/kg/day developed diarrhea with increased stool water from approximately 60% to greater than 80%, which was reduced by up to 75% by the K+ channel inhibitors clotrimazole or senicapoc or the CFTR inhibitor (R)-BPO-27. These results indicate a mechanism for TKI diarrhea involving K+ and Cl- channel activation and support the therapeutic efficacy of channel inhibitors.
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Affiliation(s)
- Tianying Duan
- Departments of Medicine and Physiology, UCSF, San Francisco, California, USA.,Department of Gastroenterology, The Second Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Onur Cil
- Departments of Medicine and Physiology, UCSF, San Francisco, California, USA.,Department of Pediatrics, UCSF, San Francisco, California, USA
| | - Jay R Thiagarajah
- Division of Gastroenterology, Hepatology and Nutrition, Boston Children's Hospital, Boston, Massachusetts, USA.,Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, USA
| | - Alan S Verkman
- Departments of Medicine and Physiology, UCSF, San Francisco, California, USA
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24
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Klinger S, Lange P, Brandt E, Hustedt K, Schröder B, Breves G, Herrmann J. Degree of SGLT1 phosphorylation is associated with but does not determine segment-specific glucose transport features in the porcine small intestines. Physiol Rep 2018; 6. [PMID: 29333720 PMCID: PMC5789657 DOI: 10.14814/phy2.13562] [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: 08/28/2017] [Revised: 11/29/2017] [Accepted: 12/04/2017] [Indexed: 12/18/2022] Open
Abstract
Glucose‐induced electrogenic ion transport is higher in the porcine ileum compared with the jejunum despite equal apical abundance of SGLT1. The objective of this study was a detailed determination of SGLT1 and GLUT2 expressions at mRNA and protein levels along the porcine small intestinal axis. Phosphorylation of SGLT1 at serine 418 was assessed as a potential modulator of activity. Porcine intestinal tissues taken along the intestinal axis 1 h or 3 h after feeding were analyzed for relative mRNA (RT‐PCR) and protein levels (immunoblot) of SGLT1, pSGLT1, GLUT2, (p)AMPK, β2‐receptor, and PKA substrates. Functional studies on electrogenic glucose transport were done (Ussing chambers: short circuit currents (Isc)). Additionally, effects of epinephrine (Epi) administration on segment‐specific glucose transport and pSGLT1 content were examined. SGLT1 and GLUT2 expression was similar throughout the small intestines but lower in the duodenum and distal ileum. pSGLT1 abundance was significantly lower in the ileum compared with the jejunum associated with significantly higher glucose‐induced Isc. SGLT1 phosphorylation was not inducible by Epi. Epi treatment decreased glucose‐induced Isc and glucose flux rates in the jejunum but increased basal Isc in the ileum. Epi‐induced PKA activation was detectable in jejunal tissue. These results may indicate that SGLT1 phosphorylation at Ser418 represents a structural change to compensate for certain conditions that may decrease glucose transport (unfavorable driving forces/changed apical membrane potential) rather than being the cause for the overall differences in glucose transport characteristics between the jejunum and ileum.
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Affiliation(s)
- Stefanie Klinger
- Department of Physiology, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany
| | - Patrick Lange
- Department of Physiology, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany
| | - Elisabeth Brandt
- Department of Physiology, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany
| | - Karin Hustedt
- Department of Physiology, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany
| | - Bernd Schröder
- Department of Physiology, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany
| | - Gerhard Breves
- Department of Physiology, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany
| | - Jens Herrmann
- Department of Physiology, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany
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25
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Rajendran VM, Sandle GI. Colonic Potassium Absorption and Secretion in Health and Disease. Compr Physiol 2018; 8:1513-1536. [PMID: 30215859 PMCID: PMC9769410 DOI: 10.1002/cphy.c170030] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The colon has large capacities for K+ absorption and K+ secretion, but its role in maintaining K+ homeostasis is often overlooked. For many years, passive diffusion and/or solvent drag were thought to be the primary mechanisms for K+ absorption in human and animal colon. However, it is now clear that apical H+ ,K+ -ATPase, in coordination with basolateral K+ -Cl- cotransport and/or K+ and Cl- channels operating in parallel, mediate electroneutral K+ absorption in animal colon. We now know that K+ absorption in rat colon reflects ouabain-sensitive and ouabain-insensitive apical H+ ,K+ -ATPase activities. Ouabain-insensitive and ouabain-sensitive H+ ,K+ -ATPases are localized in surface and crypt cells, respectively. Colonic H+ ,K+ -ATPase consists of α- (HKCα ) and β- (HKCβ ) subunits which, when coexpressed, exhibit ouabain-insensitive H+ ,K+ -ATPase activity in HEK293 cells, while HKCα coexpressed with the gastric β-subunit exhibits ouabain-sensitive H+ ,K+ -ATPase activity in Xenopus oocytes. Aldosterone enhances apical H+ ,K+ -ATPase activity, HKCα specific mRNA and protein expression, and K+ absorption. Active K+ secretion, on the other hand, is mediated by apical K+ channels operating in a coordinated way with the basolateral Na+ -K+ -2Cl- cotransporter. Both Ca2+ -activated intermediate conductance K+ (IK) and large conductance K+ (BK) channels are located in the apical membrane of colonic epithelia. IK channel-mediated K+ efflux provides the driving force for Cl- secretion, while BK channels mediate active (e.g., cAMP-activated) K+ secretion. BK channel expression and activity are increased in patients with end-stage renal disease and ulcerative colitis. This review summarizes the role of apical H+ ,K+ -ATPase in K+ absorption, and apical BK channel function in K+ secretion in health and disease. © 2018 American Physiological Society. Compr Physiol 8:1513-1536, 2018.
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Affiliation(s)
| | - Geoffrey I. Sandle
- Leeds Institute of Biomedical and Clinical Sciences, St James’s University Hospital, Leeds LS9 7TF, UK
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26
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Brown BM, Pressley B, Wulff H. KCa3.1 Channel Modulators as Potential Therapeutic Compounds for Glioblastoma. Curr Neuropharmacol 2018; 16:618-626. [PMID: 28676010 PMCID: PMC5997873 DOI: 10.2174/1570159x15666170630164226] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2017] [Revised: 06/01/2017] [Accepted: 06/22/2017] [Indexed: 12/31/2022] Open
Abstract
Background The intermediate-conductance Ca2+-activated K+ channel KCa3.1 is widely expressed in cells of the immune system such as T- and B-lymphocytes, mast cells, macrophages and microglia, but also found in dedifferentiated vascular smooth muscle cells, fibroblasts and many cancer cells including pancreatic, prostate, leukemia and glioblastoma. In all these cell types KCa3.1 plays an important role in cellular activation, migration and proliferation by regulating membrane potential and Ca2+ signaling. Methods and Results KCa3.1 therefore constitutes an attractive therapeutic target for diseases involving excessive proliferation or activation of one more of these cell types and researchers both in academia and in the pharmaceutical industry have developed several potent and selective small molecule inhibitors of KCa3.1. This article will briefly review the available compounds (TRAM-34, senicapoc, NS6180), their binding sites and mechanisms of action, and then discuss the potential usefulness of these compounds for the treatment of brain tumors based on their brain penetration and their efficacy in reducing microglia activation in animal models of ischemic stroke and Alzheimer’s disease. Conclusion Senicapoc, which has previously been in Phase III clinical trials, would be available for repurposing, and could be used to quickly translate findings made with other KCa3.1 blocking tool compounds into clinical trials.
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Affiliation(s)
- Brandon M Brown
- Department of Pharmacology, School of Medicine, University of California, Davis, CA 95616, United States
| | - Brandon Pressley
- Department of Pharmacology, School of Medicine, University of California, Davis, CA 95616, United States
| | - Heike Wulff
- Department of Pharmacology, School of Medicine, University of California, Davis, CA 95616, United States
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27
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Klinger S, Breves G. Resveratrol Inhibits Porcine Intestinal Glucose and Alanine Transport: Potential Roles of Na⁺/K⁺-ATPase Activity, Protein Kinase A, AMP-Activated Protein Kinase and the Association of Selected Nutrient Transport Proteins with Detergent Resistant Membranes. Nutrients 2018; 10:nu10030302. [PMID: 29510506 PMCID: PMC5872720 DOI: 10.3390/nu10030302] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Revised: 02/24/2018] [Accepted: 03/01/2018] [Indexed: 12/22/2022] Open
Abstract
Background: Beneficial effects of Resveratrol (RSV) have been demonstrated, including effects on transporters and channels. However, little is known about how RSV influences intestinal transport. The aim of this study was to further characterize the effects of RSV on intestinal transport and the respective mechanisms. Methods: Porcine jejunum and ileum were incubated with RSV (300 µM, 30 min) in Ussing chambers (functional studies) and tissue bathes (detection of protein expression, phosphorylation, association with detergent resistant membranes (DRMs)). Results: RSV reduced alanine and glucose-induced short circuit currents (ΔIsc) and influenced forskolin-induced ΔIsc. The phosphorylation of sodium–glucose-linked transporter 1 (SGLT1), AMP-activated protein kinase (AMPK), protein kinase A substrates (PKA-S) and liver kinase B1 (LKB1) increased but a causative relation to the inhibitory effects could not directly be established. The DRM association of SGLT1, peptide transporter 1 (PEPT1) and (phosphorylated) Na+/H+-exchanger 3 (NHE3) did not change. Conclusion: RSV influences the intestinal transport of glucose, alanine and chloride and is likely to affect other transport processes. As the effects of protein kinase activation vary between the intestinal localizations, it would appear that increasing cyclic adenosine monophosphate (cAMP) levels are part of the mechanism. Nonetheless, the physiological responses depend on cell type-specific structures.
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Affiliation(s)
- Stefanie Klinger
- Department of Physiology, University of Veterinary Medicine Hannover, Foundation, Bischofsholer Damm 15, 30173 Hannover, Germany.
| | - Gerhard Breves
- Department of Physiology, University of Veterinary Medicine Hannover, Foundation, Bischofsholer Damm 15, 30173 Hannover, Germany.
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28
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Goff JP. Invited review: Mineral absorption mechanisms, mineral interactions that affect acid-base and antioxidant status, and diet considerations to improve mineral status. J Dairy Sci 2018; 101:2763-2813. [PMID: 29397180 DOI: 10.3168/jds.2017-13112] [Citation(s) in RCA: 168] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Accepted: 12/06/2017] [Indexed: 12/18/2022]
Abstract
Several minerals are required for life to exist. In animals, 7 elements (Ca, P, Mg, Na, K, Cl, and S) are required to be present in the diet in fairly large amounts (grams to tens of grams each day for the dairy cow) and are termed macrominerals. Several other elements are termed microminerals or trace minerals because they are required in much smaller amounts (milligrams to micrograms each day). In most cases the mineral in the diet must be absorbed across the gastrointestinal mucosa and enter the blood if it is to be of value to the animal. The bulk of this review discusses the paracellular and transcellular mechanisms used by the gastrointestinal tract to absorb each of the various minerals needed. Unfortunately, particularly in ruminants, interactions between minerals and other substances within the diet can occur within the digestive tract that impair mineral absorption. The attributes of organic or chelated minerals that might permit diet minerals to circumvent factors that inhibit absorption of more traditional inorganic forms of these minerals are discussed. Once absorbed, minerals are used in many ways. One focus of this review is the effect macrominerals have on the acid-base status of the animal. Manipulation of dietary cation and anion content is commonly used as a tool in the dry period and during lactation to improve performance. A section on how the strong ion theory can be used to understand these effects is included. Many microminerals play a role in the body as cofactors of enzymes involved in controlling free radicals within the body and are vital to antioxidant capabilities. Those same minerals, when consumed in excess, can become pro-oxidants in the body, generating destructive free radicals. Complex interactions between minerals can compromise the effectiveness of a diet in promoting health and productivity of the cow. The objective of this review is to provide insight into some of these mechanisms.
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Affiliation(s)
- Jesse P Goff
- Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames 50011.
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29
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Stumpff F. A look at the smelly side of physiology: transport of short chain fatty acids. Pflugers Arch 2018; 470:571-598. [PMID: 29305650 DOI: 10.1007/s00424-017-2105-9] [Citation(s) in RCA: 92] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Revised: 12/19/2017] [Accepted: 12/20/2017] [Indexed: 12/14/2022]
Abstract
Fermentative organs such as the caecum, the colon, and the rumen have evolved to produce and absorb energy rich short chain fatty acids (SCFA) from otherwise indigestible substrates. Classical models postulate diffusional uptake of the undissociated acid (HSCFA). However, in net terms, a major part of SCFA absorption occurs with uptake of Na+ and resembles classical, coupled electroneutral NaCl transport. Considerable evidence suggests that the anion transporting proteins expressed by epithelia of fermentative organs are poorly selective and that their main function may be to transport acetate-, propionate-, butyrate- and HCO3- as the physiologically relevant anions. Apical uptake of SCFA thus involves non-saturable diffusion of the undissociated acid (HSCFA), SCFA-/HCO3- exchange via DRA (SLC26A3) and/or SCFA--H+ symport (MCT1, SLC16A1). All mechanisms lead to cytosolic acidification with stimulation of Na+/H+ exchange via NHE (SLC9A2/3). Basolaterally, Na+ leaves via the Na+/K+-ATPase with recirculation of K+. Na+ efflux drives the transport of SCFA- anions through volume-regulated anion channels, such as maxi-anion channels (possibly SLCO2A1), LRRC8, anoctamins, or uncoupled exchangers. When luminal buffering is inadequate, basolateral efflux will increasingly involve SCFA-/ HCO3- exchange (AE1/2, SCL4A1/2), or efflux of SCFA- with H+ (MCT1/4, SLC16A1/3). Furthermore, protons can be basolaterally removed by NHE1 (SCL9A1) or NBCe1 (SLC4A4). The purpose of these transport proteins is to maximize the amount of SCFA transported from the tightly buffered ingesta while minimizing acid transport through the epithelium. As known from the rumen for many decades, a disturbance of these processes is likely to cause severe colonic disease.
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Affiliation(s)
- Friederike Stumpff
- Institute of Veterinary Physiology, Department of Veterinary Medicine, Freie Universität Berlin, Oertzenweg 19b, 14163, Berlin, Germany.
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30
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Julio-Kalajzić F, Villanueva S, Burgos J, Ojeda M, Cid LP, Jentsch TJ, Sepúlveda FV. K 2P TASK-2 and KCNQ1-KCNE3 K + channels are major players contributing to intestinal anion and fluid secretion. J Physiol 2017; 596:393-407. [PMID: 29143340 DOI: 10.1113/jp275178] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2017] [Accepted: 11/08/2017] [Indexed: 12/11/2022] Open
Abstract
KEY POINTS K+ channels are important in intestinal epithelium as they ensure the ionic homeostasis and electrical potential of epithelial cells during anion and fluid secretion. Intestinal epithelium cAMP-activated anion secretion depends on the activity of the (also cAMP dependent) KCNQ1-KCNE3 K+ channel, but the secretory process survives after genetic inactivation of the K+ channel in the mouse. Here we use double mutant mice to investigate which alternative K+ channels come into action to compensate for the absence of KCNQ1-KCNE3 K+ channels. Our data establish that whilst Ca2+ -activated KCa 3.1 channels are not involved, K2P two-pore domain TASK-2 K+ channels are major players providing an alternative conductance to sustain the intestinal secretory process. Work with double mutant mice lacking both TASK-2 and KCNQ1-KCNE3 channels nevertheless points to yet-unidentified K+ channels that contribute to the robustness of the cAMP-activated anion secretion process. ABSTRACT Anion and fluid secretion across the intestinal epithelium, a process altered in cystic fibrosis and secretory diarrhoea, is mediated by cAMP-activated CFTR Cl- channels and requires the simultaneous activity of basolateral K+ channels to maintain cellular ionic homeostasis and membrane potential. This function is fulfilled by the cAMP-activated K+ channel formed by the association of pore-forming KCNQ1 with its obligatory KCNE3 β-subunit. Studies using mice show sizeable cAMP-activated intestinal anion secretion in the absence of either KCNQ1 or KCNE3 suggesting that an alternative K+ conductance must compensate for the loss of KCNQ1-KCNE3 activity. We used double mutant mouse and pharmacological approaches to identify such a conductance. Ca2+ -dependent anion secretion can also be supported by Ca2+ -dependent KCa 3.1 channels after independent CFTR activation, but cAMP-dependent anion secretion is not further decreased in the combined absence of KCa 3.1 and KCNQ1-KCNE3 K+ channel activity. We show that the K2P K+ channel TASK-2 is expressed in the epithelium of the small and large intestine. Tetrapentylammonium, a TASK-2 inhibitor, abolishes anion secretory current remaining in the absence of KCNQ1-KCNE3 activity. A double mutant mouse lacking both KCNQ1-KCNE3 and TASK-2 showed a much reduced cAMP-mediated anion secretion compared to that observed in the single KCNQ1-KCNE3 deficient mouse. We conclude that KCNQ1-KCNE3 and TASK-2 play major roles in the intestinal anion and fluid secretory phenotype. The persistence of an, admittedly reduced, secretory activity in the absence of these two conductances suggests that further additional K+ channel(s) as yet unidentified contribute to the robustness of the intestinal anion secretory process.
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Affiliation(s)
| | - Sandra Villanueva
- Centro de Estudios Científicos (CECs), Avenida Arturo Prat 514, Valdivia, Chile.,Universidad Austral de Chile, Valdivia, Chile
| | - Johanna Burgos
- Centro de Estudios Científicos (CECs), Avenida Arturo Prat 514, Valdivia, Chile.,Universidad Austral de Chile, Valdivia, Chile
| | - Margarita Ojeda
- Centro de Estudios Científicos (CECs), Avenida Arturo Prat 514, Valdivia, Chile
| | - L Pablo Cid
- Centro de Estudios Científicos (CECs), Avenida Arturo Prat 514, Valdivia, Chile
| | - Thomas J Jentsch
- Leibniz-Institut für Molekulare Pharmakologie (FMP) and Max-Delbrück-Centrum für Molekulare Medizin (MDC), Berlin, Germany
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31
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Jiang S, Zhu L, Yang J, Hu L, Gu J, Xing X, Sun Y, Zhang Z. Integrated expression profiling of potassium channels identifys KCNN4 as a prognostic biomarker of pancreatic cancer. Biochem Biophys Res Commun 2017; 494:113-119. [DOI: 10.1016/j.bbrc.2017.10.072] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Accepted: 10/15/2017] [Indexed: 12/21/2022]
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32
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Han J, Lee SH, Giebisch G, Wang T. Potassium Channelopathies and Gastrointestinal Ulceration. Gut Liver 2017; 10:881-889. [PMID: 27784845 PMCID: PMC5087926 DOI: 10.5009/gnl15414] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Revised: 10/14/2015] [Accepted: 10/20/2015] [Indexed: 12/13/2022] Open
Abstract
Potassium channels and transporters maintain potassium homeostasis and play significant roles in several different biological actions via potassium ion regulation. In previous decades, the key revelations that potassium channels and transporters are involved in the production of gastric acid and the regulation of secretion in the stomach have been recognized. Drugs used to treat peptic ulceration are often potassium transporter inhibitors. It has also been reported that potassium channels are involved in ulcerative colitis. Direct toxicity to the intestines from nonsteroidal anti-inflammatory drugs has been associated with altered potassium channel activities. Several reports have indicated that the long-term use of the antianginal drug Nicorandil, an adenosine triphosphate-sensitive potassium channel opener, increases the chances of ulceration and perforation from the oral to anal regions throughout the gastrointestinal (GI) tract. Several of these drug features provide further insights into the role of potassium channels in the occurrence of ulceration in the GI tract. The purpose of this review is to investigate whether potassium channelopathies are involved in the mechanisms responsible for ulceration that occurs throughout the GI tract.
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Affiliation(s)
- Jaeyong Han
- Department of Cellular and Molecular Physiology, Yale University, New Haven, CT, USA
| | - Seung Hun Lee
- Department of Internal Medicine, Section of Nephrology, Yale University, New Haven, CT, USA
| | - Gerhard Giebisch
- Department of Cellular and Molecular Physiology, Yale University, New Haven, CT, USA
| | - Tong Wang
- Department of Cellular and Molecular Physiology, Yale University, New Haven, CT, USA
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33
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Ali MK, Li X, Tang Q, Liu X, Chen F, Xiao J, Ali M, Chou SH, He J. Regulation of Inducible Potassium Transporter KdpFABC by the KdpD/KdpE Two-Component System in Mycobacterium smegmatis. Front Microbiol 2017; 8:570. [PMID: 28484428 PMCID: PMC5401905 DOI: 10.3389/fmicb.2017.00570] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Accepted: 03/20/2017] [Indexed: 12/28/2022] Open
Abstract
Kdp-ATPase is an inducible high affinity potassium uptake system that is widely distributed in bacteria, and is generally regulated by the KdpD/KdpE two-component system (TCS). In this study, conducted on Mycobacterium smegmatis, the kdpFABC (encoding Kdp-ATPase) expression was found to be affected by low concentration of K+, high concentrations of Na+, and/or [Formula: see text] of the medium. The KdpE was found to be a transcriptional regulator that bound to a specific 22-bp sequence in the promoter region of kdpFABC operon to positively regulate kdpFABC expression. The KdpE binding motif was highly conserved in the promoters of kdpFABC among the mycobacterial species. 5'-RACE data indicated a transcriptional start site (TSS) of the kdpFABC operon within the coding sequence of MSMEG_5391, which comprised a 120-bp long 5'-UTR and an open reading frame of the 87-bp kdpF gene. The kdpE deletion resulted in altered growth rate under normal and low K+ conditions. Furthermore, under K+ limiting conditions, a single transcript (kdpFABCDE) spanning kdpFABC and kdpDE operons was observed. This study provided the first insight into the regulation of kdpFABC operon by the KdpD/KdpE TCS in M. smegmatis.
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Affiliation(s)
- Maria K Ali
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural UniversityWuhan, China
| | - Xinfeng Li
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural UniversityWuhan, China
| | - Qing Tang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural UniversityWuhan, China
| | - Xiaoyu Liu
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural UniversityWuhan, China
| | - Fang Chen
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural UniversityWuhan, China
| | - Jinfeng Xiao
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural UniversityWuhan, China
| | - Muhammad Ali
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural UniversityWuhan, China.,Biotechnology Program, Department of Environmental Sciences, COMSATS Institute of Information TechnologyAbbottabad, Pakistan
| | - Shan-Ho Chou
- Institute of Biochemistry and NCHU Agricultural Biotechnology Center, National Chung Hsing UniversityTaichung, Taiwan
| | - Jin He
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural UniversityWuhan, China
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34
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Nguyen HM, Singh V, Pressly B, Jenkins DP, Wulff H, Yarov-Yarovoy V. Structural Insights into the Atomistic Mechanisms of Action of Small Molecule Inhibitors Targeting the KCa3.1 Channel Pore. Mol Pharmacol 2017; 91:392-402. [PMID: 28126850 PMCID: PMC5363711 DOI: 10.1124/mol.116.108068] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Accepted: 01/19/2017] [Indexed: 12/13/2022] Open
Abstract
The intermediate-conductance Ca2+-activated K+ channel (KCa3.1) constitutes an attractive pharmacological target for immunosuppression, fibroproliferative disorders, atherosclerosis, and stroke. However, there currently is no available crystal structure of this medically relevant channel that could be used for structure-assisted drug design. Using the Rosetta molecular modeling suite we generated a molecular model of the KCa3.1 pore and tested the model by first confirming previously mapped binding sites and visualizing the mechanism of TRAM-34 (1-[(2-chlorophenyl)diphenylmethyl]-1H-pyrazole), senicapoc (2,2-bis-(4-fluorophenyl)-2-phenylacetamide), and NS6180 (4-[[3-(trifluoromethyl)phenyl]methyl]-2H-1,4-benzothiazin-3(4H)-one) inhibition at the atomistic level. All three compounds block ion conduction directly by fully or partially occupying the site that would normally be occupied by K+ before it enters the selectivity filter. We then challenged the model to predict the receptor sites and mechanisms of action of the dihydropyridine nifedipine and an isosteric 4-phenyl-pyran. Rosetta predicted receptor sites for nifedipine in the fenestration region and for the 4-phenyl-pyran in the pore lumen, which could both be confirmed by site-directed mutagenesis and electrophysiology. While nifedipine is thus not a pore blocker and might be stabilizing the channel in a nonconducting conformation or interfere with gating, the 4-phenyl-pyran was found to be a classical pore blocker that directly inhibits ion conduction similar to the triarylmethanes TRAM-34 and senicapoc. The Rosetta KCa3.1 pore model explains the mechanism of action of several KCa3.1 blockers at the molecular level and could be used for structure-assisted drug design.
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Affiliation(s)
- Hai M Nguyen
- Department of Pharmacology (H.M.N, V.S., B.P., D.P.J., H.W.) and Department of Physiology and Membrane Biology (V. Y.-Y.), School of Medicine, University of California at Davis, Davis, California
| | - Vikrant Singh
- Department of Pharmacology (H.M.N, V.S., B.P., D.P.J., H.W.) and Department of Physiology and Membrane Biology (V. Y.-Y.), School of Medicine, University of California at Davis, Davis, California
| | - Brandon Pressly
- Department of Pharmacology (H.M.N, V.S., B.P., D.P.J., H.W.) and Department of Physiology and Membrane Biology (V. Y.-Y.), School of Medicine, University of California at Davis, Davis, California
| | - David Paul Jenkins
- Department of Pharmacology (H.M.N, V.S., B.P., D.P.J., H.W.) and Department of Physiology and Membrane Biology (V. Y.-Y.), School of Medicine, University of California at Davis, Davis, California
| | - Heike Wulff
- Department of Pharmacology (H.M.N, V.S., B.P., D.P.J., H.W.) and Department of Physiology and Membrane Biology (V. Y.-Y.), School of Medicine, University of California at Davis, Davis, California
| | - Vladimir Yarov-Yarovoy
- Department of Pharmacology (H.M.N, V.S., B.P., D.P.J., H.W.) and Department of Physiology and Membrane Biology (V. Y.-Y.), School of Medicine, University of California at Davis, Davis, California
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35
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Fló M, Margenat M, Pellizza L, Graña M, Durán R, Báez A, Salceda E, Soto E, Alvarez B, Fernández C. Functional diversity of secreted cestode Kunitz proteins: Inhibition of serine peptidases and blockade of cation channels. PLoS Pathog 2017; 13:e1006169. [PMID: 28192542 PMCID: PMC5325619 DOI: 10.1371/journal.ppat.1006169] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2016] [Revised: 02/24/2017] [Accepted: 01/06/2017] [Indexed: 01/01/2023] Open
Abstract
We previously reported a multigene family of monodomain Kunitz proteins from Echinococcus granulosus (EgKU-1-EgKU-8), and provided evidence that some EgKUs are secreted by larval worms to the host interface. In addition, functional studies and homology modeling suggested that, similar to monodomain Kunitz families present in animal venoms, the E. granulosus family could include peptidase inhibitors as well as channel blockers. Using enzyme kinetics and whole-cell patch-clamp, we now demonstrate that the EgKUs are indeed functionally diverse. In fact, most of them behaved as high affinity inhibitors of either chymotrypsin (EgKU-2-EgKU-3) or trypsin (EgKU-5-EgKU-8). In contrast, the close paralogs EgKU-1 and EgKU-4 blocked voltage-dependent potassium channels (Kv); and also pH-dependent sodium channels (ASICs), while showing null (EgKU-1) or marginal (EgKU-4) peptidase inhibitory activity. We also confirmed the presence of EgKUs in secretions from other parasite stages, notably from adult worms and metacestodes. Interestingly, data from genome projects reveal that at least eight additional monodomain Kunitz proteins are encoded in the genome; that particular EgKUs are up-regulated in various stages; and that analogous Kunitz families exist in other medically important cestodes, but not in trematodes. Members of this expanded family of secreted cestode proteins thus have the potential to block, through high affinity interactions, the function of host counterparts (either peptidases or cation channels) and contribute to the establishment and persistence of infection. From a more general perspective, our results confirm that multigene families of Kunitz inhibitors from parasite secretions and animal venoms display a similar functional diversity and thus, that host-parasite co-evolution may also drive the emergence of a new function associated with the Kunitz scaffold.
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Affiliation(s)
- Martín Fló
- Cátedra de Inmunología, Facultad de Química, Universidad de la República, Montevideo, Uruguay
- Laboratorio de Enzimología, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay
| | - Mariana Margenat
- Cátedra de Inmunología, Facultad de Química, Universidad de la República, Montevideo, Uruguay
| | - Leonardo Pellizza
- Cátedra de Inmunología, Facultad de Química, Universidad de la República, Montevideo, Uruguay
| | - Martín Graña
- Unidad de Bioinformática, Institut Pasteur de Montevideo, Montevideo, Uruguay
| | - Rosario Durán
- Unidad de Bioquímica y Proteómica Analíticas, Institut Pasteur de Montevideo and Instituto de Investigaciones Biológicas Clemente Estable, Montevideo, Uruguay
| | - Adriana Báez
- Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, Puebla, México
| | - Emilio Salceda
- Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, Puebla, México
| | - Enrique Soto
- Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, Puebla, México
| | - Beatriz Alvarez
- Laboratorio de Enzimología, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay
| | - Cecilia Fernández
- Cátedra de Inmunología, Facultad de Química, Universidad de la República, Montevideo, Uruguay
- * E-mail:
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Zhang Y, Feng Y, Chen L, Zhu J. Effects of Intermediate-Conductance Ca(2+)-Activated K(+) Channels on Human Endometrial Carcinoma Cells. Cell Biochem Biophys 2017; 72:515-25. [PMID: 25608633 DOI: 10.1007/s12013-014-0497-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The objective of this study was to investigate the effect of intermediate-conductance Ca(2+)-activated K(+) (KCa3.1) channels on the cell proliferation, cell cycle, apoptosis, migration, and invasion in endometrial cancer (EC) cells. Human EC cell lines HEC-1-A and Ishikawa were cultured in vitro and transfected with recombinant plasmid containing KCa3.1-targeting shRNA. RT-qPCR and Western blot were used to examine the mRNA and protein expression levels of KCa3.1 channels in transfected cells. In addition, the specific inhibitor of KCa3.1, TRAM-34, was used to examine the effect of KCa3.1 blockage on migration capacity and invasiveness of EC cells using transwell assay. Proliferation and apoptotic rates of EC cells transfected with KCa3.1 shRNA or treated with TRAM-34 were analyzed using MTT, BrdU incorporation assay, and flow cytometry. Expression of cell cycle proteins and metalloproteinase-2 (MMP-2) was evaluated by RT-qPCR and Western blotting. TRAM-34 treatment and KCa3.1 silencing using shRNA dramatically suppressed both the mRNA and protein expression of KCa3.1 channels (P < 0.01) compared with control groups. Blockage of KCa3.1 by TRAM-34 treatment and KCa3.1 shRNA transfection exerted inhibitory effect on cell growth of both EC cell lines, as demonstrated by increased cell population at G0-G1 phase and decreased cell population at S phase. However, both the treatments did not result in significant changes in the apoptotic rate (P > 0.05) compared to controls. Protein expressions of cyclin D1, cyclin E, and survivin were significantly decreased in the experimental groups comparing to control. We showed that TRAM-34 treatment led to significantly inhibited migration, invasion, and MMP-2 expression in HEC-1-A and Ishikawa cells, compared with the control group (P < 0.01). Blockage of KCa3.1 channel activity or expression inhibits cell proliferation and cell cycle progression without inducing apoptosis in EC cells. Moreover, TRAM-34 could reduce the ability of EC cells to migrate and invade, which might be related to reduced expression of MMP-2.
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Affiliation(s)
- Yingli Zhang
- Department of Gynecologic Oncology, Zhejiang Cancer Hospital, 38 Guangji Road, Hangzhou, 310022, China
| | - Youji Feng
- Shanghai Jiao Tong University Affiliated First People's Hospital, Shanghai, 200080, China
| | - Lu Chen
- Department of Gynecologic Oncology, Zhejiang Cancer Hospital, 38 Guangji Road, Hangzhou, 310022, China.
| | - Jianqing Zhu
- Department of Gynecologic Oncology, Zhejiang Cancer Hospital, 38 Guangji Road, Hangzhou, 310022, China
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Turck D, Bresson JL, Burlingame B, Dean T, Fairweather-Tait S, Heinonen M, Hirsch-Ernst KI, Mangelsdorf I, McArdle H, Neuhäuser-Berthold M, Nowicka G, Pentieva K, Sanz Y, Siani A, Sjödin A, Stern M, Tomé D, Van Loveren H, Vinceti M, Willatts P, Aggett P, Martin A, Przyrembel H, Brönstrup A, Ciok J, Gómez Ruiz JÁ, de Sesmaisons-Lecarré A, Naska A. Dietary reference values for potassium. EFSA J 2016. [DOI: 10.2903/j.efsa.2016.4592] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
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Klinger S, Schröder B, Gemmer A, Reimers J, Breves G, Herrmann J, Wilkens MR. Gastrointestinal transport of calcium and glucose in lactating ewes. Physiol Rep 2016; 4:4/11/e12817. [PMID: 27273883 PMCID: PMC4908493 DOI: 10.14814/phy2.12817] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Accepted: 04/29/2016] [Indexed: 01/26/2023] Open
Abstract
During lactation, mineral and nutrient requirements increase dramatically, particularly those for Ca and glucose. In contrast to monogastric species, in ruminants, it is rather unclear to which extend this physiological change due to increased demand for milk production is accompanied by functional adaptations of the gastrointestinal tract (GIT). Therefore, we investigated potential modulations of Ca and glucose transport mechanisms in the GIT of lactating and dried‐off sheep. Ussing‐chamber technique was applied to determine the ruminal and jejunal Ca flux rates. In the jejunum, electrophysiological properties in response to glucose were recorded. Jejunal brush‐border membrane vesicles (BBMV) served to characterize glucose uptake via sodium‐linked glucose transporter 1 (SGLT1), and RNA and protein expression levels of Ca and glucose transporting systems were determined. Ruminal Ca flux rate data showed a trend for higher absorption in lactating sheep. In the jejunum, small Ca absorption could only be observed in lactating ewes. From the results, it may be assumed that lactating ewes compensate for the Ca loss by increasing bone mobilization rather than by increasing supply through absorption from the GIT. Presence of SGLT1 in the jejunum of both groups was shown by RNA and protein identification, but glucose uptake into BBMV could only be detected in lactating sheep. This, however, could not be attributed to electrogenic glucose absorption in lactating sheep under Ussing‐chamber conditions, providing evidence that changes in jejunal glucose uptake may include additional factors, that is, posttranslational modifications such as phosphorylation.
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Affiliation(s)
- Stefanie Klinger
- Department of Physiology, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany
| | - Bernd Schröder
- Department of Physiology, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany
| | - Anja Gemmer
- Department of Physiology, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany
| | - Julia Reimers
- Department of Physiology, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany
| | - Gerhard Breves
- Department of Physiology, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany
| | - Jens Herrmann
- Department of Physiology, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany
| | - Mirja R Wilkens
- Department of Physiology, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany
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Karwad MA, Macpherson T, Wang B, Theophilidou E, Sarmad S, Barrett DA, Larvin M, Wright KL, Lund JN, O'Sullivan SE. Oleoylethanolamine and palmitoylethanolamine modulate intestinal permeability in vitro via TRPV1 and PPARα. FASEB J 2016; 31:469-481. [PMID: 27623929 DOI: 10.1096/fj.201500132] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Accepted: 08/15/2016] [Indexed: 12/26/2022]
Abstract
Cannabinoids modulate intestinal permeability through cannabinoid receptor 1 (CB1). The endocannabinoid-like compounds oleoylethanolamine (OEA) and palmitoylethanolamine (PEA) play an important role in digestive regulation, and we hypothesized they would also modulate intestinal permeability. Transepithelial electrical resistance (TEER) was measured in human Caco-2 cells to assess permeability after application of OEA and PEA and relevant antagonists. Cells treated with OEA and PEA were stained for cytoskeletal F-actin changes and lysed for immunoassay. OEA and PEA were measured by liquid chromatography-tandem mass spectrometry. OEA (applied apically, logEC50 -5.4) and PEA (basolaterally, logEC50 -4.9; apically logEC50 -5.3) increased Caco-2 resistance by 20-30% via transient receptor potential vanilloid (TRPV)-1 and peroxisome proliferator-activated receptor (PPAR)-α. Preventing their degradation (by inhibiting fatty acid amide hydrolase) enhanced the effects of OEA and PEA. OEA and PEA induced cytoskeletal changes and activated focal adhesion kinase and ERKs 1/2, and decreased Src kinases and aquaporins 3 and 4. In Caco-2 cells treated with IFNγ and TNFα, OEA (via TRPV1) and PEA (via PPARα) prevented or reversed the cytokine-induced increased permeability compared to vehicle (0.1% ethanol). PEA (basolateral) also reversed increased permeability when added 48 or 72 h after cytokines (P < 0.001, via PPARα). Cellular and secreted levels of OEA and PEA (P < 0.001-0.001) were increased in response to inflammatory mediators. OEA and PEA have endogenous roles and potential therapeutic applications in conditions of intestinal hyperpermeability and inflammation.-Karwad, M. A., Macpherson, T., Wang, B., Theophilidou, E., Sarmad, S., Barrett, D. A., Larvin, M., Wright, K. L., Lund, J. N., O'Sullivan, S. E. Oleoylethanolamine and palmitoylethanolamine modulate intestinal permeability in vitro via TRPV1 and PPARα.
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Affiliation(s)
- Mustafa A Karwad
- School of Medicine, Royal Derby Hospital, University of Nottingham, Nottingham, United Kingdom
| | - Tara Macpherson
- Division of Biomedical and Life Sciences, Faculty of Health and Medicine, Lancaster University, Lancaster, United Kingdom
| | - Bo Wang
- Division of Biomedical and Life Sciences, Faculty of Health and Medicine, Lancaster University, Lancaster, United Kingdom
| | - Elena Theophilidou
- School of Medicine, Royal Derby Hospital, University of Nottingham, Nottingham, United Kingdom
| | - Sarir Sarmad
- Centre for Analytical Bioscience, School of Pharmacy, University of Nottingham, Nottingham, United Kingdom; and
| | - David A Barrett
- Centre for Analytical Bioscience, School of Pharmacy, University of Nottingham, Nottingham, United Kingdom; and
| | - Michael Larvin
- Graduate Entry Medical School, University of Limerick, Limerick, Ireland.,Health Research Institute, University of Limerick, Limerick, Ireland
| | - Karen L Wright
- Division of Biomedical and Life Sciences, Faculty of Health and Medicine, Lancaster University, Lancaster, United Kingdom
| | - Jonathan N Lund
- School of Medicine, Royal Derby Hospital, University of Nottingham, Nottingham, United Kingdom
| | - Saoirse E O'Sullivan
- School of Medicine, Royal Derby Hospital, University of Nottingham, Nottingham, United Kingdom;
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Association of serum electrolytes and smoking with salivary gland stone formation. Int J Oral Maxillofac Surg 2016; 45:764-8. [PMID: 26969301 DOI: 10.1016/j.ijom.2016.02.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Revised: 12/28/2015] [Accepted: 02/16/2016] [Indexed: 11/21/2022]
Abstract
To further define potential factors that may contribute to stone formation in salivary glands (sialolithiasis), a retrospective chart review was performed of patients diagnosed with sialolithiasis between March 1, 1998 and February 29, 2012. Information on salivary gland stone number, location and size, medical history, medications, and serum electrolyte levels were collected. Associations between electrolyte levels and stone characteristics (such as stone number and size) were examined. Fifty-nine patients were identified; their median age was 58 years (range 25-89 years) and most were male (95%). Salivary stones were most commonly located in the submandibular glands (83%). Thirty-five patients (59%) had a smoking history, with 16 (27%) reported as current smokers. There was a significant association between current smoker status and stone size (mean largest stone size 12.4±8.8mm vs. 7.5±4.8mm in current smokers vs. non-smokers; P=0.03). Serum sodium levels (r=0.32, P=0.014) and serum potassium levels (r=0.31, P=0.017) showed significant positive correlations with stone size. While the aetiology of sialolithiasis remains unclear, smoking (which can contribute to reduced saliva flow) and higher serum sodium levels (which can reflect volume depletion) are associated with larger salivary stones.
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Slomka T, Lennon ES, Akbar H, Gosmanova EO, Bhattacharya SK, Oliphant CS, Khouzam RN. Effects of Renin-Angiotensin-Aldosterone System Blockade in Patients with End-Stage Renal Disease. Am J Med Sci 2016; 351:309-16. [DOI: 10.1016/j.amjms.2015.12.021] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Accepted: 12/04/2015] [Indexed: 01/27/2023]
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Marie C, Verkerke HP, Theodorescu D, Petri WA. A whole-genome RNAi screen uncovers a novel role for human potassium channels in cell killing by the parasite Entamoeba histolytica. Sci Rep 2015; 5:13613. [PMID: 26346926 PMCID: PMC4561901 DOI: 10.1038/srep13613] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Accepted: 07/30/2015] [Indexed: 01/29/2023] Open
Abstract
The parasite Entamoeba histolytica kills human cells resulting in ulceration, inflammation and invasion of the colonic epithelium. We used the cytotoxic properties of ameba to select a genome-wide RNAi library to reveal novel host factors that control susceptibility to amebic killing. We identified 281 candidate susceptibility genes and bioinformatics analyses revealed that ion transporters were significantly enriched among susceptibility genes. Potassium (K+) channels were the most common transporter identified. Their importance was further supported by colon biopsy of humans with amebiasis that demonstrated suppressed K+ channel expression. Inhibition of human K+ channels by genetic silencing, pharmacologic inhibitors and with excess K+ protected diverse cell types from E. histolytica-induced death. Contact with E. histolytica parasites triggered K+ channel activation and K+ efflux by intestinal epithelial cells, which preceded cell killing. Specific inhibition of Ca2+-dependent K+ channels was highly effective in preventing amebic cytotoxicity in intestinal epithelial cells and macrophages. Blockade of K+ efflux also inhibited caspase-1 activation, IL-1β secretion and pyroptotic death in THP-1 macrophages. We concluded that K+ channels are host mediators of amebic cytotoxicity in multiple cells types and of inflammasome activation in macrophages.
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Affiliation(s)
- Chelsea Marie
- Division of Infectious Diseases and International Health, University of Virginia School of Medicine, Charlottesville, Virginia USA
| | - Hans P Verkerke
- Division of Infectious Diseases and International Health, University of Virginia School of Medicine, Charlottesville, Virginia USA
| | - Dan Theodorescu
- Department of Surgery, Department of Pharmacology, University of Colorado Comprehensive Cancer Center, University of Colorado, Denver, CO, USA
| | - William A Petri
- Division of Infectious Diseases and International Health, University of Virginia School of Medicine, Charlottesville, Virginia USA
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Yuan J, Liu W, Karvar S, Baker SS, He W, Baker RD, Ji G, Xie J, Zhu L. Potassium channel KCNJ15 is required for histamine-stimulated gastric acid secretion. Am J Physiol Cell Physiol 2015; 309:C264-70. [DOI: 10.1152/ajpcell.00012.2015] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Accepted: 06/17/2015] [Indexed: 12/14/2022]
Abstract
Gastric acid secretion is mediated by the K+-dependent proton pump (H+,K+-ATPase), which requires a continuous supply of K+ at the luminal side of the apical membrane. Several K+ channels are implicated in gastric acid secretion. However, the identity of the K+ channel(s) responsible for apical K+ supply is still elusive. Our previous studies have shown the translocation of KCNJ15 from cytoplasmic vesicles to the apical membrane on stimulation, indicating its involvement in gastric acid secretion. In this study, the stimulation associated trafficking of KCNJ15 was observed in a more native context with a live cell imaging system. KCNJ15 molecules in resting live cells were scattered in cytoplasm but exhibited apical localization after stimulation. Furthermore, knocking down KCNJ15 expression with a short hairpin RNA adenoviral construct abolished histamine-stimulated acid secretion in rabbit primary parietal cells. Moreover, KCNJ15, like H+,K+-ATPase, was detected in all of the parietal cells by immunofluorescence staining, whereas only about half of the parietal cells were positive for KCNQ1 under the same condition. Consistently, the endogenous protein levels of KCNJ15, analyzed by Western blotting, were higher than those of KCNQ1 in the gastric mucosa of human, mouse, and rabbit. These results provide evidence for a major role of KCNJ15 in apical K+ supply during stimulated acid secretion.
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Affiliation(s)
- Jianye Yuan
- Institute of Digestive Diseases, Longhua Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Wensheng Liu
- Digestive Diseases and Nutrition Center, Department of Pediatrics, State University of New York at Buffalo, Buffalo, New York; and
| | - Serhan Karvar
- Department of Medicine, Medical University of South Carolina, Charleston, South Carolina
| | - Susan S. Baker
- Digestive Diseases and Nutrition Center, Department of Pediatrics, State University of New York at Buffalo, Buffalo, New York; and
| | - Wenjun He
- Digestive Diseases and Nutrition Center, Department of Pediatrics, State University of New York at Buffalo, Buffalo, New York; and
| | - Robert D. Baker
- Digestive Diseases and Nutrition Center, Department of Pediatrics, State University of New York at Buffalo, Buffalo, New York; and
| | - Guang Ji
- Institute of Digestive Diseases, Longhua Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Jianqun Xie
- Institute of Digestive Diseases, Longhua Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Lixin Zhu
- Institute of Digestive Diseases, Longhua Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China
- Digestive Diseases and Nutrition Center, Department of Pediatrics, State University of New York at Buffalo, Buffalo, New York; and
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Abstract
PURPOSE OF REVIEW Hypertension and hyperglycaemia are major risk factors that result in chronic kidney disease (CKD). Achievement of blood pressure goals, optimal control of blood glucose levels and the use of agents to block the renin-angiotensin-aldosterone system slow the progression of CKD. However, not all patients are benefited by these interventions and novel strategies to arrest or reverse the pathological processes inherent in CKD are needed. The therapeutic potential of targeting KCa3.1 in CKD will be discussed in this review. RECENT FINDINGS Blockade of KCa3.1 ameliorates activation of renal fibroblasts in diabetic mice by inhibiting the transforming growth factor-β1/small mothers against decapentaplegic pathway. A concomitant reduction in nuclear factor-κB activation in human proximal tubular cells under diabetic conditions has been observed. Advanced glycosylated endproducts induce both protein expression and current density of KCa3.1, which, in turn, mediates migration and proliferation of vascular smooth muscle cells via Ca²⁺-dependent signalling pathways. SUMMARY Studies have clearly demonstrated a causal role of chronic hyperglycaemia and hypertension in the development of CKD. However, a large proportion of patients develop end-stage kidney disease despite strict glycaemic control and the attainment of recommended blood pressure goals. Therefore, it is essential to identify and validate novel targets to reduce the development and progression of CKD. Recent findings demonstrate that genetic deletion or pharmacologic inhibition of KCa3.1 significantly reduces the development of diabetic nephropathy in animal models. However, the consequences of blockade of KCa3.1 in preventing and treating established diabetic nephropathy in humans warrants further study.
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Duan Z, Chen S, Sun C, Shi F, Wu G, Liu A, Xu G, Yang N. Polymorphisms in Ion Transport Genes Are Associated with Eggshell Mechanical Property. PLoS One 2015; 10:e0130160. [PMID: 26106883 PMCID: PMC4481273 DOI: 10.1371/journal.pone.0130160] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Accepted: 05/16/2015] [Indexed: 11/19/2022] Open
Abstract
Eggshell mechanical property traits such as eggshell breaking strength (ESS), eggshell thickness (EST) and eggshell weight (ESW) are most common and important indexes to evaluate eggshell quality in poultry industry. Uterine ion transporters involve in eggshell formation and might be associated with eggshell mechanical property traits. In this study, 99 SNPs in 15 ion transport genes were selected to genotype 976 pedigreed hens of Rhode Island Red. ESS, EST and ESW were measured for each bird at 55 weeks of age. The association study showed that 14 SNPs in 8 genes were significantly related (p < 0.05) with at least one trait, and their contributions to phenotypic variance ranged from 0.23% to 4.14%. Both ATP2A3 and SLC4A5 had a significant effect on all the three traits. Strong linkage disequilibrium (LD) was detected among SNPs in four genes: ATP2A3, ITPR1, SLC8A3, SCNN1a. The significant effects of those diplotypes on eggshell mechanical property traits were found, and their contributions to phenotypic variance ranged from 0.50% to 0.70%. It was concluded that the identified SNPs and diplotypes in this study were potential markers influencing the eggshell mechanical properties, which could contribute to the genetic improvement of eggshell quality.
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Affiliation(s)
- Zhongyi Duan
- National Engineering Laboratory for Animal Breeding and MOA Key Laboratory of Animal Genetics and Breeding, College of Animal Science and Technology, China Agricultural University, Beijing, China
| | - Sirui Chen
- National Engineering Laboratory for Animal Breeding and MOA Key Laboratory of Animal Genetics and Breeding, College of Animal Science and Technology, China Agricultural University, Beijing, China
| | - Congjiao Sun
- National Engineering Laboratory for Animal Breeding and MOA Key Laboratory of Animal Genetics and Breeding, College of Animal Science and Technology, China Agricultural University, Beijing, China
| | - Fengying Shi
- Beijing Huadu Yukou Poultry Industry Co., Ltd., Beijing, China
| | - Guiqin Wu
- Beijing Huadu Yukou Poultry Industry Co., Ltd., Beijing, China
| | - Aiqiao Liu
- Beijing Huadu Yukou Poultry Industry Co., Ltd., Beijing, China
| | - Guiyun Xu
- National Engineering Laboratory for Animal Breeding and MOA Key Laboratory of Animal Genetics and Breeding, College of Animal Science and Technology, China Agricultural University, Beijing, China
| | - Ning Yang
- National Engineering Laboratory for Animal Breeding and MOA Key Laboratory of Animal Genetics and Breeding, College of Animal Science and Technology, China Agricultural University, Beijing, China
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Sahara Y, Horie S, Fukami H, Goto-Matsumoto N, Nakanishi-Matsui M. Functional roles of V-ATPase in the salivary gland. J Oral Biosci 2015. [DOI: 10.1016/j.job.2014.11.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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47
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Chiang NJ, Wu SN, Chen LT. The potent activation of Ca2+-activated K+ current by NVP-AUY922 in the human pancreatic duct cell line (PANC-1) possibly independent of heat shock protein 90 inhibition. J Pharmacol Sci 2015; 127:404-13. [DOI: 10.1016/j.jphs.2015.02.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Revised: 02/02/2015] [Accepted: 02/12/2015] [Indexed: 12/20/2022] Open
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Renigunta V, Schlichthörl G, Daut J. Much more than a leak: structure and function of K₂p-channels. Pflugers Arch 2015; 467:867-94. [PMID: 25791628 DOI: 10.1007/s00424-015-1703-7] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Accepted: 03/09/2015] [Indexed: 11/27/2022]
Abstract
Over the last decade, we have seen an enormous increase in the number of experimental studies on two-pore-domain potassium channels (K2P-channels). The collection of reviews and original articles compiled for this special issue of Pflügers Archiv aims to give an up-to-date summary of what is known about the physiology and pathophysiology of K2P-channels. This introductory overview briefly describes the structure of K2P-channels and their function in different organs. Its main aim is to provide some background information for the 19 reviews and original articles of this special issue of Pflügers Archiv. It is not intended to be a comprehensive review; instead, this introductory overview focuses on some unresolved questions and controversial issues, such as: Do K2P-channels display voltage-dependent gating? Do K2P-channels contribute to the generation of action potentials? What is the functional role of alternative translation initiation? Do K2P-channels have one or two or more gates? We come to the conclusion that we are just beginning to understand the extremely complex regulation of these fascinating channels, which are often inadequately described as 'leak channels'.
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Affiliation(s)
- Vijay Renigunta
- Institute of Physiology and Pathophysiology, Marburg University, 35037, Marburg, Germany
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Sepúlveda FV, Pablo Cid L, Teulon J, Niemeyer MI. Molecular aspects of structure, gating, and physiology of pH-sensitive background K2P and Kir K+-transport channels. Physiol Rev 2015; 95:179-217. [PMID: 25540142 DOI: 10.1152/physrev.00016.2014] [Citation(s) in RCA: 77] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
K(+) channels fulfill roles spanning from the control of excitability to the regulation of transepithelial transport. Here we review two groups of K(+) channels, pH-regulated K2P channels and the transport group of Kir channels. After considering advances in the molecular aspects of their gating based on structural and functional studies, we examine their participation in certain chosen physiological and pathophysiological scenarios. Crystal structures of K2P and Kir channels reveal rather unique features with important consequences for the gating mechanisms. Important tasks of these channels are discussed in kidney physiology and disease, K(+) homeostasis in the brain by Kir channel-equipped glia, and central functions in the hearing mechanism in the inner ear and in acid secretion by parietal cells in the stomach. K2P channels fulfill a crucial part in central chemoreception probably by virtue of their pH sensitivity and are central to adrenal secretion of aldosterone. Finally, some unorthodox behaviors of the selectivity filters of K2P channels might explain their normal and pathological functions. Although a great deal has been learned about structure, molecular details of gating, and physiological functions of K2P and Kir K(+)-transport channels, this has been only scratching at the surface. More molecular and animal studies are clearly needed to deepen our knowledge.
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Affiliation(s)
- Francisco V Sepúlveda
- Centro de Estudios Científicos, Valdivia, Chile; UPMC Université Paris 06, Team 3, Paris, France; and Institut National de la Santé et de la Recherche Médicale, UMR_S 1138, Paris, France
| | - L Pablo Cid
- Centro de Estudios Científicos, Valdivia, Chile; UPMC Université Paris 06, Team 3, Paris, France; and Institut National de la Santé et de la Recherche Médicale, UMR_S 1138, Paris, France
| | - Jacques Teulon
- Centro de Estudios Científicos, Valdivia, Chile; UPMC Université Paris 06, Team 3, Paris, France; and Institut National de la Santé et de la Recherche Médicale, UMR_S 1138, Paris, France
| | - María Isabel Niemeyer
- Centro de Estudios Científicos, Valdivia, Chile; UPMC Université Paris 06, Team 3, Paris, France; and Institut National de la Santé et de la Recherche Médicale, UMR_S 1138, Paris, France
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Affiliation(s)
- Lonny R. Levin
- Department of Pharmacology, Weill Cornell Medical College, New York, NY 10065; ,
| | - Jochen Buck
- Department of Pharmacology, Weill Cornell Medical College, New York, NY 10065; ,
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