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Guo J, Zhang C, Zhao H, Yan Y, Liu Z. The key mediator of diabetic kidney disease: Potassium channel dysfunction. Genes Dis 2024; 11:101119. [PMID: 38523672 PMCID: PMC10958065 DOI: 10.1016/j.gendis.2023.101119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 06/11/2022] [Accepted: 06/04/2023] [Indexed: 03/26/2024] Open
Abstract
Diabetic kidney disease is a leading cause of end-stage renal disease, making it a global public health concern. The molecular mechanisms underlying diabetic kidney disease have not been elucidated due to its complex pathogenesis. Thus, exploring these mechanisms from new perspectives is the current focus of research concerning diabetic kidney disease. Ion channels are important proteins that maintain the physiological functions of cells and organs. Among ion channels, potassium channels stand out, because they are the most common and important channels on eukaryotic cell surfaces and function as the basis for cell excitability. Certain potassium channel abnormalities have been found to be closely related to diabetic kidney disease progression and genetic susceptibility, such as KATP, KCa, Kir, and KV. In this review, we summarized the roles of different types of potassium channels in the occurrence and development of diabetic kidney disease to discuss whether the development of DKD is due to potassium channel dysfunction and present new ideas for the treatment of DKD.
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Affiliation(s)
- Jia Guo
- Nephrology Research Center, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan 450052, China
- Key Laboratory of Precision Diagnosis and Treatment for Chronic Kidney Disease in Henan Province, Zhengzhou, Henan 450052, China
- Research Center for Kidney Disease, Zhengzhou, Henan 450052, China
| | - Chaojie Zhang
- Nephrology Research Center, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan 450052, China
- Key Laboratory of Precision Diagnosis and Treatment for Chronic Kidney Disease in Henan Province, Zhengzhou, Henan 450052, China
- Research Center for Kidney Disease, Zhengzhou, Henan 450052, China
| | - Hui Zhao
- Nephrology Research Center, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan 450052, China
- Key Laboratory of Precision Diagnosis and Treatment for Chronic Kidney Disease in Henan Province, Zhengzhou, Henan 450052, China
- Research Center for Kidney Disease, Zhengzhou, Henan 450052, China
| | - Yufan Yan
- Nephrology Research Center, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan 450052, China
- Key Laboratory of Precision Diagnosis and Treatment for Chronic Kidney Disease in Henan Province, Zhengzhou, Henan 450052, China
- Research Center for Kidney Disease, Zhengzhou, Henan 450052, China
| | - Zhangsuo Liu
- Nephrology Research Center, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan 450052, China
- Key Laboratory of Precision Diagnosis and Treatment for Chronic Kidney Disease in Henan Province, Zhengzhou, Henan 450052, China
- Research Center for Kidney Disease, Zhengzhou, Henan 450052, China
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2
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Dates J, Kolosov D. Voltage-gated ion channels as novel regulators of epithelial ion transport in the osmoregulatory organs of insects. FRONTIERS IN INSECT SCIENCE 2024; 4:1385895. [PMID: 38835480 PMCID: PMC11148248 DOI: 10.3389/finsc.2024.1385895] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2024] [Accepted: 05/01/2024] [Indexed: 06/06/2024]
Abstract
Voltage-gated ion channels (VGICs) respond to changes in membrane potential (Vm) and typically exhibit fast kinetic properties. They play an important role in signal detection and propagation in excitable tissues. In contrast, the role of VGICs in non-excitable tissues like epithelia is less studied and less clear. Studies in epithelia of vertebrates and invertebrates demonstrate wide expression of VGICs in epithelia of animals. Recently, VGICs have emerged as regulators of ion transport in the Malpighian tubules (MTs) and other osmoregulatory organs of insects. This mini-review aims to concisely summarize which VGICs have been implicated in the regulation of ion transport in the osmoregulatory epithelia of insects to date, and highlight select groups for further study. We have also speculated on the roles VGICs may potentially play in regulating processes connected directly to ion transport in insects (e.g., acid-base balance, desiccation, thermal tolerance). This review is not meant to be exhaustive but should rather serve as a thought-provoking collection of select existing highlights on VGICs, and to emphasize how understudied this mechanism of ion transport regulation is in insect epithelia.
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Affiliation(s)
- Jocelyne Dates
- Department of Biological Sciences, California State University San Marcos, San Marcos, CA, United States
| | - Dennis Kolosov
- Department of Biological Sciences, California State University San Marcos, San Marcos, CA, United States
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3
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Li Z, McComic S, Chen R, Kim WTH, Gaithuma AK, Mooney B, Macaluso KR, Mulenga A, Swale DR. ATP-sensitive inward rectifier potassium channels regulate secretion of pro-feeding salivary proteins in the lone star tick (Amblyomma americanum). Int J Biol Macromol 2023; 253:126545. [PMID: 37652342 DOI: 10.1016/j.ijbiomac.2023.126545] [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: 05/17/2023] [Revised: 08/22/2023] [Accepted: 08/24/2023] [Indexed: 09/02/2023]
Abstract
Understanding the physiological and molecular regulation of tick feeding is necessary for developing intervention strategies to curb disease transmission by ticks. Pharmacological activation of ATP-gated inward rectifier potassium (KATP) channels reduced fluid secretion from isolated salivary gland and blood feeding in the lone star tick, Amblyomma americanum, yet the temporal expression pattern of KATP channel proteins remained unknown. KATP channels were highly expressed in type II and III acini in off-host stage and early feeding phase ticks, yet expression was reduced in later stages of feeding. We next assessed KATP channel regulation of the secreted proteome of tick saliva. LC-MS/MS analysis identified 40 differentially secreted tick saliva proteins after exposure to KATP activators or inhibitors. Secretion of previously validated tick saliva proteins that promote tick feeding, AV422, AAS27, and AAS41 were significantly reduced by upwards of 8 log units in ticks exposed to KATP channel activators when compared to untreated ticks. Importantly, activation of KATP channels inhibited tick feeding and vice versa for KATP channel inhibitors. Data indicate KATP channels regulate tick feeding biology by controlling secretion of pro-feeding proteins that are essential during early feeding phases, which provides insights into physiological and molecular regulation of tick feeding behavior.
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Affiliation(s)
- Zhilin Li
- Department of Entomology, Louisiana State University AgCenter, Baton Rouge, LA, United States of America; Emerging Pathogens Institute, Department of Entomology and Nematology, University of Florida, Gainesville, FL 32610, USA
| | - Sarah McComic
- Emerging Pathogens Institute, Department of Entomology and Nematology, University of Florida, Gainesville, FL 32610, USA
| | - Rui Chen
- Emerging Pathogens Institute, Department of Entomology and Nematology, University of Florida, Gainesville, FL 32610, USA
| | - William Tae Heung Kim
- Department of Veterinary pathobiology, College of Veterinary Medicine, Texas A&M University, College Station, TX, USA
| | - Alex Kiarie Gaithuma
- Department of Veterinary pathobiology, College of Veterinary Medicine, Texas A&M University, College Station, TX, USA
| | - Brian Mooney
- Department of Biochemistry, Charles W Gehrlke Proteomics Center, University of Missouri, MO, USA
| | - Kevin R Macaluso
- Department of Microbiology and Immunology, College of Medicine, University of South Alabama, Mobile, AL, USA
| | - Albert Mulenga
- Department of Veterinary pathobiology, College of Veterinary Medicine, Texas A&M University, College Station, TX, USA
| | - Daniel R Swale
- Emerging Pathogens Institute, Department of Entomology and Nematology, University of Florida, Gainesville, FL 32610, USA.
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4
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Emerging mechanisms involving brain Kv7 channel in the pathogenesis of hypertension. Biochem Pharmacol 2022; 206:115318. [PMID: 36283445 DOI: 10.1016/j.bcp.2022.115318] [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: 08/24/2022] [Revised: 10/15/2022] [Accepted: 10/17/2022] [Indexed: 12/14/2022]
Abstract
Hypertension is a prevalent health problem inducing many organ damages. The pathogenesis of hypertension involves a complex integration of different organ systems including the brain. The elevated sympathetic nerve activity is closely related to the etiology of hypertension. Ion channels are critical regulators of neuronal excitability. Several mechanisms have been proposed to contribute to hypothalamic-driven elevated sympathetic activity, including altered ion channel function. Recent findings indicate one of the voltage-gated potassium channels, Kv7 channels (M channels), plays a vital role in regulating cardiovascular-related neurons activity, and the expression of Kv7 channels is downregulated in hypertension. This review highlights recent findings that the Kv7 channels in the brain, blood vessels, and kidneys are emerging targets involved in the pathogenesis of hypertension, suggesting new therapeutic targets for treating drug-resistant, neurogenic hypertension.
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5
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Abstract
The kidney maintains electrolyte, water, and acid-base balance, eliminates foreign and waste compounds, regulates blood pressure, and secretes hormones. There are at least 16 different highly specialized epithelial cell types in the mammalian kidney. The number of specialized endothelial cells, immune cells, and interstitial cell types might even be larger. The concerted interplay between different cell types is critical for kidney function. Traditionally, cells were defined by their function or microscopical morphological appearance. With the advent of new single-cell modalities such as transcriptomics, epigenetics, metabolomics, and proteomics we are entering into a new era of cell type definition. This new technological revolution provides new opportunities to classify cells in the kidney and understand their functions.
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Affiliation(s)
- Michael S Balzer
- Department of Medicine, Renal Electrolyte and Hypertension Division, University of Pennsylvania, Philadelphia, Pennsylvania, USA;
- Institute of Diabetes Obesity and Metabolism, University of Pennsylvania, Philadelphia, Philadelphia, USA
| | - Tibor Rohacs
- Department of Pharmacology, Physiology and Neuroscience, Rutgers New Jersey Medical School, Newark, New Jersey, USA
| | - Katalin Susztak
- Department of Medicine, Renal Electrolyte and Hypertension Division, University of Pennsylvania, Philadelphia, Pennsylvania, USA;
- Institute of Diabetes Obesity and Metabolism, University of Pennsylvania, Philadelphia, Philadelphia, USA
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6
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Marcoux AA, Tremblay LE, Slimani S, Fiola MJ, Mac-Way F, Haydock L, Garneau AP, Isenring P. Anatomophysiology of the Henle's Loop: Emphasis on the Thick Ascending Limb. Compr Physiol 2021; 12:3119-3139. [PMID: 34964111 DOI: 10.1002/cphy.c210021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The loop of Henle plays a variety of important physiological roles through the concerted actions of ion transport systems in both its apical and basolateral membranes. It is involved most notably in extracellular fluid volume and blood pressure regulation as well as Ca2+ , Mg2+ , and acid-base homeostasis because of its ability to reclaim a large fraction of the ultrafiltered solute load. This nephron segment is also involved in urinary concentration by energizing several of the steps that are required to generate a gradient of increasing osmolality from cortex to medulla. Another important role of the loop of Henle is to sustain a process known as tubuloglomerular feedback through the presence of specialized renal tubular cells that lie next to the juxtaglomerular arterioles. This article aims at describing these physiological roles and at discussing a number of the molecular mechanisms involved. It will also report on novel findings and uncertainties regarding the realization of certain processes and on the pathophysiological consequences of perturbed salt handling by the thick ascending limb of the loop of Henle. Since its discovery 150 years ago, the loop of Henle has remained in the spotlight and is now generating further interest because of its role in the renal-sparing effect of SGLT2 inhibitors. © 2022 American Physiological Society. Compr Physiol 12:1-21, 2022.
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Affiliation(s)
- Andrée-Anne Marcoux
- Nephrology Research Group, Department of Medicine, Laval University, Québec, QC, Canada
| | - Laurence E Tremblay
- Nephrology Research Group, Department of Medicine, Laval University, Québec, QC, Canada
| | - Samira Slimani
- Nephrology Research Group, Department of Medicine, Laval University, Québec, QC, Canada
| | - Marie-Jeanne Fiola
- Nephrology Research Group, Department of Medicine, Laval University, Québec, QC, Canada
| | - Fabrice Mac-Way
- Nephrology Research Group, Department of Medicine, Laval University, Québec, QC, Canada
| | - Ludwig Haydock
- Nephrology Research Group, Department of Medicine, Laval University, Québec, QC, Canada
| | - Alexandre P Garneau
- Nephrology Research Group, Department of Medicine, Laval University, Québec, QC, Canada.,Cardiometabolic Axis, School of Kinesiology and Physical Activity Sciences, University of Montréal, Montréal, QC, Canada
| | - Paul Isenring
- Nephrology Research Group, Department of Medicine, Laval University, Québec, QC, Canada
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7
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Wiencke JK, Zhang Z, Koestler DC, Salas LA, Molinaro AM, Christensen BC, Kelsey KT. Identification of a foetal epigenetic compartment in adult human kidney. Epigenetics 2021; 17:335-355. [PMID: 33783321 DOI: 10.1080/15592294.2021.1900027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
The mammalian kidney has extensive repair capacity; however, identifying adult renal stem cells has proven elusive. We applied an epigenetic marker of foetal cell origin (FCO) in diverse human tissues as a probe for developmental cell persistence, finding a 5.4-fold greater FCO proportion in kidney. Normal kidney FCO proportions averaged 49% with extensive interindividual variation. FCO proportions were significantly negatively correlated with immune-related gene expression and positively correlated with genes expressed in the renal medulla, including those involved in renal organogenesis (e.g., FGF2, PAX8, and HOXB7). FCO associated genes also mapped to medullary nephron segments in mouse and rat, suggesting evolutionary conservation of this cellular compartment. Renal cancer patients whose tumours contained non-zero FCO scores survived longer. The kidney appears unique in possessing substantial foetal epigenetic features. Further study of FCO-related gene methylation may elucidate regenerative regulatory programmes in tissues without apparent discrete stem cell compartments.
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Affiliation(s)
- John K Wiencke
- Department of Neurological Surgery, Institute for Human Genetics, University of California, San Francisco, CA, USA
| | - Ze Zhang
- Department of Epidemiology, Department of Pathology and Laboratory Medicine, Brown University School of Public Health, Providence, RI, USA
| | - Devin C Koestler
- Department of Biostatistics, University of Kansas Medical Center, Kansas City, KS, USA
| | - Lucas A Salas
- Department of Epidemiology, Department of Molecular and Systems Biology, Department of Community and Family Medicine, Geisel School of Medicine, Dartmouth College, Lebanon, NH, USA
| | - Annette M Molinaro
- Department of Neurological Surgery, Institute for Human Genetics, University of California, San Francisco, CA, USA
| | - Brock C Christensen
- Department of Epidemiology, Department of Molecular and Systems Biology, Department of Community and Family Medicine, Geisel School of Medicine, Dartmouth College, Lebanon, NH, USA
| | - Karl T Kelsey
- Department of Epidemiology, Department of Pathology and Laboratory Medicine, Brown University School of Public Health, Providence, RI, USA
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8
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Abstract
Kv7.1-Kv7.5 (KCNQ1-5) K+ channels are voltage-gated K+ channels with major roles in neurons, muscle cells and epithelia where they underlie physiologically important K+ currents, such as neuronal M current and cardiac IKs. Specific biophysical properties of Kv7 channels make them particularly well placed to control the activity of excitable cells. Indeed, these channels often work as 'excitability breaks' and are targeted by various hormones and modulators to regulate cellular activity outputs. Genetic deficiencies in all five KCNQ genes result in human excitability disorders, including epilepsy, arrhythmias, deafness and some others. Not surprisingly, this channel family attracts considerable attention as potential drug targets. Here we will review biophysical properties and tissue expression profile of Kv7 channels, discuss recent advances in the understanding of their structure as well as their role in various neurological, cardiovascular and other diseases and pathologies. We will also consider a scope for therapeutic targeting of Kv7 channels for treatment of the above health conditions.
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9
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Marcoux AA, Tremblay LE, Slimani S, Fiola MJ, Mac-Way F, Garneau AP, Isenring P. Molecular characteristics and physiological roles of Na + -K + -Cl - cotransporter 2. J Cell Physiol 2020; 236:1712-1729. [PMID: 32776569 PMCID: PMC7818487 DOI: 10.1002/jcp.29997] [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: 02/26/2020] [Revised: 06/28/2020] [Accepted: 07/24/2020] [Indexed: 12/23/2022]
Abstract
Na+–K+–Cl− cotransporter 2 (NKCC2; SLC12A1) is an integral membrane protein that comes as three splice variants and mediates the cotranslocation of Na+, K+, and Cl− ions through the apical membrane of the thick ascending loop of Henle (TALH). In doing so, and through the involvement of other ion transport systems, it allows this nephron segment to reclaim a large fraction of the ultrafiltered Na+, Cl−, Ca2+, Mg2+, and HCO3− loads. The functional relevance of NKCC2 in human is illustrated by the many abnormalities that result from the inactivation of this transport system through the use of loop diuretics or in the setting of inherited disorders. The following presentation aims at discussing the physiological roles and molecular characteristics of Na+–K+–Cl− cotransport in the TALH and those of the individual NKCC2 splice variants more specifically. Many of the historical and recent data that have emerged from the experiments conducted will be outlined and their larger meaning will also be placed into perspective with the aid of various hypotheses.
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Affiliation(s)
- Andree-Anne Marcoux
- Department of Medicine, Nephrology Research Group, Laval University, Quebec City, Québec, Canada
| | - Laurence E Tremblay
- Department of Medicine, Nephrology Research Group, Laval University, Quebec City, Québec, Canada
| | - Samira Slimani
- Department of Medicine, Nephrology Research Group, Laval University, Quebec City, Québec, Canada
| | - Marie-Jeanne Fiola
- Department of Medicine, Nephrology Research Group, Laval University, Quebec City, Québec, Canada
| | - Fabrice Mac-Way
- Department of Medicine, Nephrology Research Group, Laval University, Quebec City, Québec, Canada
| | - Alexandre P Garneau
- Department of Medicine, Nephrology Research Group, Laval University, Quebec City, Québec, Canada.,Cardiometabolic Axis, School of Kinesiology and Physical Activity Sciences, University of Montréal, Montréal, Quebec, Canada
| | - Paul Isenring
- Department of Medicine, Nephrology Research Group, Laval University, Quebec City, Québec, Canada
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Zhang J, Han J, Li L, Zhang Q, Feng Y, Jiang Y, Deng F, Zhang Y, Wu Q, Chen B, Hu J. Inwardly rectifying potassium channel 5.1: Structure, function, and possible roles in diseases. Genes Dis 2020; 8:272-278. [PMID: 33997174 PMCID: PMC8093645 DOI: 10.1016/j.gendis.2020.03.006] [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: 11/27/2019] [Revised: 03/02/2020] [Accepted: 03/13/2020] [Indexed: 11/30/2022] Open
Abstract
Inwardly rectifying potassium (Kir) channels make it easier for K+ to enter into a cell and subsequently regulate cellular biological functions. Kir5.1 (encoded by KCNJ16) alone can form a homotetramer and can form heterotetramers with Kir4.1 (encoded by KCNJ10) or Kir4.2 (encoded by KCNJ15). In most cases, homomeric Kir5.1 is non-functional, while heteromeric Kir5.1 on the cell membrane contributes to the inward flow of K+ ions, which can be regulated by intracellular pH and a variety of signaling mechanisms. In the form of a heterotetramer, Kir5.1 regulates Kir4.1/4.2 activity and is involved in the maintenance of nephron function. Actually, homomeric Kir5.1 may also play a very important role in diseases, including in the ventilatory response to hypoxia and hypercapnia, hearing impairment, cardiovascular disease and cancer. With an increase in the number of studies into the roles of Kir channels, researchers are paying more attention to the pathophysiological functions of Kir5.1. This minireview provides an overview regarding these Kir5.1 roles.
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Affiliation(s)
- Junhui Zhang
- Institute of Burn Research, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing, 400038, PR China.,State Key Laboratory of Trauma, Burns and Combined Injury, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing, 400038, PR China.,Department of Endocrinology, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing, 400038, PR China
| | - Jian Han
- Department of Obstetrics and Gynecology, Daping Hospital, Third Military Medical University (Army Medical University), Chongqing, 400042, PR China
| | - Lingfei Li
- Department of Dermatology, Daping Hospital, Third Military Medical University (Army Medical University), Chongqing, 400042, PR China
| | - Qiong Zhang
- Institute of Burn Research, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing, 400038, PR China.,State Key Laboratory of Trauma, Burns and Combined Injury, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing, 400038, PR China
| | - Yanhai Feng
- Institute of Burn Research, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing, 400038, PR China.,State Key Laboratory of Trauma, Burns and Combined Injury, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing, 400038, PR China
| | - Youzhao Jiang
- Department of Endocrinology, People's Hospital of Banan District, Chongqing, 401320, PR China
| | - Fang Deng
- Department of Endocrinology, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing, 400038, PR China
| | - Yuping Zhang
- Department of Endocrinology, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing, 400038, PR China
| | - Qinan Wu
- Department of Endocrinology, Chongqing Cancer Hospital (Chongqing University Cancer Hospital), Chongqing, 40030, PR China
| | - Bing Chen
- Department of Endocrinology, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing, 400038, PR China
| | - Jiongyu Hu
- Institute of Burn Research, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing, 400038, PR China.,State Key Laboratory of Trauma, Burns and Combined Injury, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing, 400038, PR China.,Department of Endocrinology, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing, 400038, PR China
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11
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Armando RG, Gómez DLM, Gomez DE. New drugs are not enough‑drug repositioning in oncology: An update. Int J Oncol 2020; 56:651-684. [PMID: 32124955 PMCID: PMC7010222 DOI: 10.3892/ijo.2020.4966] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Accepted: 12/16/2019] [Indexed: 11/24/2022] Open
Abstract
Drug repositioning refers to the concept of discovering novel clinical benefits of drugs that are already known for use treating other diseases. The advantages of this are that several important drug characteristics are already established (including efficacy, pharmacokinetics, pharmacodynamics and toxicity), making the process of research for a putative drug quicker and less costly. Drug repositioning in oncology has received extensive focus. The present review summarizes the most prominent examples of drug repositioning for the treatment of cancer, taking into consideration their primary use, proposed anticancer mechanisms and current development status.
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Affiliation(s)
- Romina Gabriela Armando
- Laboratory of Molecular Oncology, Science and Technology Department, National University of Quilmes, Bernal B1876, Argentina
| | - Diego Luis Mengual Gómez
- Laboratory of Molecular Oncology, Science and Technology Department, National University of Quilmes, Bernal B1876, Argentina
| | - Daniel Eduardo Gomez
- Laboratory of Molecular Oncology, Science and Technology Department, National University of Quilmes, Bernal B1876, Argentina
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12
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Wang B, Sansom SC. Potassium-sparing effects of furosemide in mice on high-potassium diets. Am J Physiol Renal Physiol 2019; 316:F970-F973. [PMID: 30838871 DOI: 10.1152/ajprenal.00614.2018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In individuals on a regular "Western" diet, furosemide induces a kaliuresis and reduction in plasma K concentration by inhibiting Na reabsorption in the thick ascending limb of Henle's loop, enhancing delivery of Na to the aldosterone-sensitive distal nephron. In the aldosterone-sensitive distal nephron, the increased Na delivery stimulates K wasting due to an exaggerated exchange of epithelial Na channel-mediated Na reabsorption of secreted K. The effects of furosemide are different in mice fed a high-K, alkaline (HK) diet: the large-conductance Ca-activated K (BK) channel, in conjunction with the BK β4-subunit (BK-α/β4), mediates K secretion from intercalated cells (IC) of the connecting tubule and collecting ducts. The urinary alkaline load is necessary for BK-α/β4-mediated K secretion in HK diet-fed mice. However, furosemide acidifies the urine by increasing vacuolar ATPase expression and acid secretion from IC, thereby inhibiting BK-α/β4-mediated K secretion and sparing K. In mice fed a low-Na, high-K (LNaHK) diet, furosemide causes a greater increase in plasma K concentration and reduction in K excretion than in HK diet-fed mice. Micropuncture of the early distal tubule of mice fed a LNaHK diet, but not a regular or a HK diet, reveals K secretion in the thick ascending limb of Henle's loop. The sites of action of K secretion in individuals consuming a high-K diet should be taken into account when diuretic agents known to waste K with low or moderate K intakes are prescribed.
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Affiliation(s)
- Bangchen Wang
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center , Omaha, Nebraska
| | - Steven C Sansom
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center , Omaha, Nebraska
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13
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Li Z, Fisher C, Gardner I, Ghosh A, Litchfield J, Maurer TS. Modeling Exposure to Understand and Predict Kidney Injury. Semin Nephrol 2019; 39:176-189. [DOI: 10.1016/j.semnephrol.2018.12.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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14
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Gonzalez-Vicente A, Saez F, Monzon CM, Asirwatham J, Garvin JL. Thick Ascending Limb Sodium Transport in the Pathogenesis of Hypertension. Physiol Rev 2019; 99:235-309. [PMID: 30354966 DOI: 10.1152/physrev.00055.2017] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The thick ascending limb plays a key role in maintaining water and electrolyte balance. The importance of this segment in regulating blood pressure is evidenced by the effect of loop diuretics or local genetic defects on this parameter. Hormones and factors produced by thick ascending limbs have both autocrine and paracrine effects, which can extend prohypertensive signaling to other structures of the nephron. In this review, we discuss the role of the thick ascending limb in the development of hypertension, not as a sole participant, but one that works within the rich biological context of the renal medulla. We first provide an overview of the basic physiology of the segment and the anatomical considerations necessary to understand its relationship with other renal structures. We explore the physiopathological changes in thick ascending limbs occurring in both genetic and induced animal models of hypertension. We then discuss the racial differences and genetic defects that affect blood pressure in humans through changes in thick ascending limb transport rates. Throughout the text, we scrutinize methodologies and discuss the limitations of research techniques that, when overlooked, can lead investigators to make erroneous conclusions. Thus, in addition to advancing an understanding of the basic mechanisms of physiology, the ultimate goal of this work is to understand our research tools, to make better use of them, and to contextualize research data. Future advances in renal hypertension research will require not only collection of new experimental data, but also integration of our current knowledge.
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Affiliation(s)
| | - Fara Saez
- Department of Physiology and Biophysics, Case Western Reserve University , Cleveland, Ohio
| | - Casandra M Monzon
- Department of Physiology and Biophysics, Case Western Reserve University , Cleveland, Ohio
| | - Jessica Asirwatham
- Department of Physiology and Biophysics, Case Western Reserve University , Cleveland, Ohio
| | - Jeffrey L Garvin
- Department of Physiology and Biophysics, Case Western Reserve University , Cleveland, Ohio
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15
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Teulon J, Planelles G, Sepúlveda FV, Andrini O, Lourdel S, Paulais M. Renal Chloride Channels in Relation to Sodium Chloride Transport. Compr Physiol 2018; 9:301-342. [DOI: 10.1002/cphy.c180024] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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16
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Coll M, Ferrer-Costa C, Pich S, Allegue C, Rodrigo E, Fernández-Fresnedo G, Barreda P, Mates J, Martinez de Francisco AL, Ortega I, Iglesias A, Campuzano O, Salas E, Arias M, Brugada R. Role of genetic and electrolyte abnormalities in prolonged QTc interval and sudden cardiac death in end-stage renal disease patients. PLoS One 2018; 13:e0200756. [PMID: 30020974 PMCID: PMC6051653 DOI: 10.1371/journal.pone.0200756] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Accepted: 07/01/2018] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND Patients with end-stage renal disease have very high mortality. In individuals on hemodialysis, cardiovascular deaths account for ~50% of all deaths in this population, mostly due to arrhythmia. To determine the causes of these arrhythmic deaths is essential in order to adopt preventive strategies. The main objective of this study was to investigate whether, the presence of QTc interval alterations, from electrolyte abnormalities or presence of rare genetic variants, could have a relationship with sudden arrhythmogenic deaths in end-stage renal disease patients. METHODS We recorded the pre- and post-dialysis QTc interval in 111 patients undergoing hemodialysis. In 47 of them, we analyzed 24 SCD-related genes including the most prevalent genes associated with long QT syndrome using a custom resequencing panel. RESULTS We found a positive although not significant association between the presence of long QTc and mortality in a subset of end-stage renal disease patients. In addition, in five patients with long QTc only after dialysis (21.7%) we detected rare potentially pathogenic genetic variants. Three out of these five carriers subsequently died suddenly. CONCLUSIONS Genetic background may be determinant in the risk of sudden cardiac death in these patients. We recommend evaluating the QTc interval before and after hemodialysis, and performing a genetic analysis of individuals with long QTc after hemodialysis.
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Affiliation(s)
- Monica Coll
- Cardiovascular Genetics Center, IDIBGI, Dr. Trueta University Hospital, Parc Hospitalari Martí i Julià, Edifici M2, Salt, Spain
| | | | - Sara Pich
- Scientific Department, Gendiag.exe., Barcelona, Spain
| | - Catarina Allegue
- Cardiovascular Genetics Center, IDIBGI, Dr. Trueta University Hospital, Parc Hospitalari Martí i Julià, Edifici M2, Salt, Spain
| | - Emilio Rodrigo
- IFIMAV-Servicio de Nefrología del Hospital Universitario Marqués de Valdecilla, Santander, Spain
| | - Gema Fernández-Fresnedo
- IFIMAV-Servicio de Nefrología del Hospital Universitario Marqués de Valdecilla, Santander, Spain
| | - Paloma Barreda
- IFIMAV-Servicio de Nefrología del Hospital Universitario Marqués de Valdecilla, Santander, Spain
| | - Jesus Mates
- Cardiovascular Genetics Center, IDIBGI, Dr. Trueta University Hospital, Parc Hospitalari Martí i Julià, Edifici M2, Salt, Spain
| | | | - Israel Ortega
- Scientific Department, Gendiag.exe., Barcelona, Spain
| | - Anna Iglesias
- Cardiovascular Genetics Center, IDIBGI, Dr. Trueta University Hospital, Parc Hospitalari Martí i Julià, Edifici M2, Salt, Spain
| | - Oscar Campuzano
- Cardiovascular Genetics Center, IDIBGI, Dr. Trueta University Hospital, Parc Hospitalari Martí i Julià, Edifici M2, Salt, Spain
| | - Eduardo Salas
- Scientific Department, Gendiag.exe., Barcelona, Spain
| | - Manuel Arias
- IFIMAV-Servicio de Nefrología del Hospital Universitario Marqués de Valdecilla, Santander, Spain
| | - Ramon Brugada
- Cardiovascular Genetics Center, IDIBGI, Dr. Trueta University Hospital, Parc Hospitalari Martí i Julià, Edifici M2, Salt, Spain
- Cardiology Service, Dr. Trueta University Hospital, Girona, Spain
- * E-mail:
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18
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Wang YF, Lafont AG, Lee YC, Hwang PP. A novel function of calcitonin gene-related peptide in body fluid Cl- homeostasis. Proc Biol Sci 2017; 283:rspb.2016.0684. [PMID: 27306053 DOI: 10.1098/rspb.2016.0684] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Accepted: 05/18/2016] [Indexed: 12/15/2022] Open
Abstract
Vertebrates need to maintain extracellular chloride (Cl(-)) concentrations to ensure the normal operation of physiological processes; the transition from aquatic to terrestrial environments necessitated the development of sophisticated mechanisms to ensure Cl(-) homeostasis in the face of fluctuating Cl(-) levels. Zebrafish calcitonin gene-related peptide (CGRP), unlike its splice variant calcitonin, does not respond to environmental Ca(2+) levels. This study aimed to test the hypothesis that CGRP is involved in the control of body fluid Cl(-) homeostasis. Acclimation to high-Cl(-) artificial water stimulated the mRNA expression of cgrp and the receptor (crlr1) when compared with low-Cl(-) CGRP knockdown induced upregulation of the Na(+)-Cl(-) co-transporter (ncc2b), while overexpression of CGRP resulted in the downregulation of ncc2b mRNA synthesis and a simultaneous decrease in Cl(-) uptake in embryos. Consistent with these findings, knockdown of either cgrp or crlr1 was found to increase the density of NCC2b-expressing cells in embryos. This is the first demonstration that CGRP acts as a hypochloremic hormone through suppressing NCC2b expression and the differentiation of NCC-expressing ionocytes. Elucidation of this novel function of CGRP in fish body fluid Cl(-) homeostasis promises to enhance our understanding of the related physiology in vertebrates.
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Affiliation(s)
- Yi-Fang Wang
- Institute of Fishery Science, National Taiwan University, Taipei, Taiwan Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan
| | - Anne-Gaëlle Lafont
- Muséum National d'Histoire Naturelle, Sorbonne Universités, Research Unit BOREA, Biology of Aquatic Organisms and Ecosystems, CNRS 7208, IRD207, UPMC, UCBN, Paris, France
| | - Yi-Chun Lee
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan
| | - Pung-Pung Hwang
- Institute of Fishery Science, National Taiwan University, Taipei, Taiwan Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan
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Fosmo AL, Skraastad ØB. The Kv7 Channel and Cardiovascular Risk Factors. Front Cardiovasc Med 2017; 4:75. [PMID: 29259974 PMCID: PMC5723334 DOI: 10.3389/fcvm.2017.00075] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Accepted: 11/21/2017] [Indexed: 12/30/2022] Open
Abstract
Potassium channels play a pivotal role in the regulation of excitability in cells such as neurons, cardiac myocytes, and vascular smooth muscle cells. The KCNQ (Kv7) family of voltage-activated K+ channels hyperpolarizes the cell and stabilizes the membrane potential. Here, we outline how Kv7 channel activity may contribute to the development of the cardiovascular risk factors such as hypertension, diabetes, and obesity. Questions and hypotheses regarding previous and future research have been raised. Alterations in the Kv7 channel may contribute to the development of cardiovascular disease (CVD). Pharmacological modification of Kv7 channels may represent a possible treatment for CVD in the future.
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Affiliation(s)
- Andreas L Fosmo
- Division of Physiology, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Øyvind B Skraastad
- Division of Physiology, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
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20
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Edwards A, Crambert G. Versatility of NaCl transport mechanisms in the cortical collecting duct. Am J Physiol Renal Physiol 2017; 313:F1254-F1263. [PMID: 28877883 DOI: 10.1152/ajprenal.00369.2017] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Revised: 08/16/2017] [Accepted: 08/31/2017] [Indexed: 12/16/2022] Open
Abstract
The cortical collecting duct (CCD) forms part of the aldosterone-sensitive distal nephron and plays an essential role in maintaining the NaCl balance and acid-base status. The CCD epithelium comprises principal cells as well as different types of intercalated cells. Until recently, transcellular Na+ transport was thought to be restricted to principal cells, whereas (acid-secreting) type A and (bicarbonate-secreting) type B intercalated cells were associated with the regulation of acid-base homeostasis. This review describes how this traditional view has been upended by several discoveries in the past decade. A series of studies has shown that type B intercalated cells can mediate electroneutral NaCl reabsorption by a mechanism involving Na+-dependent and Na+-independent Cl-/[Formula: see text] exchange, and that is energetically driven by basolateral vacuolar H+-ATPase pumps. Other research indicates that type A intercalated cells can mediate NaCl secretion, through a bumetanide-sensitive pathway that is energized by apical H+,K+-ATPase type 2 pumps operating as Na+/K+ exchangers. We also review recent findings on the contribution of the paracellular route to NaCl transport in the CCD. Last, we describe cross-talk processes, by which one CCD cell type impacts Na+/Cl- transport in another cell type. The mechanisms that have been identified to date demonstrate clearly the interdependence of NaCl and acid-base transport systems in the CCD. They also highlight the remarkable versatility of this nephron segment.
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Affiliation(s)
- Aurélie Edwards
- Sorbonne Universités, UPMC Univ Paris 06, Université Paris Descartes, Sorbonne Paris Cité, INSERM UMRS 1138, CNRS ERL 8228, Centre de Recherche des Cordeliers, Paris, France; and .,Department of Biomedical Engineering, Boston University, Boston, Massachusetts
| | - Gilles Crambert
- Sorbonne Universités, UPMC Univ Paris 06, Université Paris Descartes, Sorbonne Paris Cité, INSERM UMRS 1138, CNRS ERL 8228, Centre de Recherche des Cordeliers, Paris, France; and
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22
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Palygin O, Pochynyuk O, Staruschenko A. Role and mechanisms of regulation of the basolateral K ir 4.1/K ir 5.1K + channels in the distal tubules. Acta Physiol (Oxf) 2017; 219:260-273. [PMID: 27129733 PMCID: PMC5086442 DOI: 10.1111/apha.12703] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Revised: 01/28/2016] [Accepted: 04/28/2016] [Indexed: 12/11/2022]
Abstract
Epithelial K+ channels are essential for maintaining electrolyte and fluid homeostasis in the kidney. It is recognized that basolateral inward-rectifying K+ (Kir ) channels play an important role in the control of resting membrane potential and transepithelial voltage, thereby modulating water and electrolyte transport in the distal part of nephron and collecting duct. Monomeric Kir 4.1 (encoded by Kcnj10 gene) and heteromeric Kir 4.1/Kir 5.1 (Kir 4.1 together with Kir 5.1 (Kcnj16)) channels are abundantly expressed at the basolateral membranes of the distal convoluted tubule and the cortical collecting duct cells. Loss-of-function mutations in KCNJ10 cause EAST/SeSAME tubulopathy in humans associated with salt wasting, hypomagnesaemia, metabolic alkalosis and hypokalaemia. In contrast, mice lacking Kir 5.1 have severe renal phenotype that, apart from hypokalaemia, is the opposite of the phenotype seen in EAST/SeSAME syndrome. Experimental advances using genetic animal models provided critical insights into the physiological role of these channels in electrolyte homeostasis and the control of kidney function. Here, we discuss current knowledge about K+ channels at the basolateral membrane of the distal tubules with specific focus on the homomeric Kir 4.1 and heteromeric Kir 4.1/Kir 5.1 channels. Recently identified molecular mechanisms regulating expression and activity of these channels, such as cell acidification, dopamine, insulin and insulin-like growth factor-1, Src family protein tyrosine kinases, as well as the role of these channels in NCC-mediated transport in the distal convoluted tubules, are also described.
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Affiliation(s)
- Oleg Palygin
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Oleh Pochynyuk
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston, Houston, TX 77030, USA
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23
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TASK-1 Regulates Apoptosis and Proliferation in a Subset of Non-Small Cell Lung Cancers. PLoS One 2016; 11:e0157453. [PMID: 27294516 PMCID: PMC4905626 DOI: 10.1371/journal.pone.0157453] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Accepted: 05/31/2016] [Indexed: 12/29/2022] Open
Abstract
Lung cancer is the leading cause of cancer deaths worldwide; survival times are poor despite therapy. The role of the two-pore domain K+ (K2P) channel TASK-1 (KCNK3) in lung cancer is at present unknown. We found that TASK-1 is expressed in non-small cell lung cancer (NSCLC) cell lines at variable levels. In a highly TASK-1 expressing NSCLC cell line, A549, a characteristic pH- and hypoxia-sensitive non-inactivating K+ current was measured, indicating the presence of functional TASK-1 channels. Inhibition of TASK-1 led to significant depolarization in these cells. Knockdown of TASK-1 by siRNA significantly enhanced apoptosis and reduced proliferation in A549 cells, but not in weakly TASK-1 expressing NCI-H358 cells. Na+-coupled nutrient transport across the cell membrane is functionally coupled to the efflux of K+ via K+ channels, thus TASK-1 may potentially influence Na+-coupled nutrient transport. In contrast to TASK-1, which was not differentially expressed in lung cancer vs. normal lung tissue, we found the Na+-coupled nutrient transporters, SLC5A3, SLC5A6, and SLC38A1, transporters for myo-inositol, biotin and glutamine, respectively, to be significantly overexpressed in lung adenocarcinomas. In summary, we show for the first time that the TASK-1 channel regulates apoptosis and proliferation in a subset of NSCLC.
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24
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Zaika O, Tomilin V, Mamenko M, Bhalla V, Pochynyuk O. New perspective of ClC-Kb/2 Cl- channel physiology in the distal renal tubule. Am J Physiol Renal Physiol 2016; 310:F923-30. [PMID: 26792067 PMCID: PMC5002062 DOI: 10.1152/ajprenal.00577.2015] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Accepted: 01/14/2016] [Indexed: 12/17/2022] Open
Abstract
Since its identification as the underlying molecular cause of Bartter's syndrome type 3, ClC-Kb (ClC-K2 in rodents, henceforth it will be referred as ClC-Kb/2) is proposed to play an important role in systemic electrolyte balance and blood pressure regulation by controlling basolateral Cl(-) exit in the distal renal tubular segments from the cortical thick ascending limb to the outer medullary collecting duct. Considerable experimental and clinical effort has been devoted to the identification and characterization of disease-causing mutations as well as control of the channel by its cofactor, barttin. However, we have only begun to unravel the role of ClC-Kb/2 in different tubular segments and to reveal the regulators of its expression and function, e.g., insulin and IGF-1. In this review we discuss recent experimental evidence in this regard and highlight unexplored questions critical to understanding ClC-Kb/2 physiology in the kidney.
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Affiliation(s)
- Oleg Zaika
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston, Houston, Texas; and
| | - Viktor Tomilin
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston, Houston, Texas; and
| | - Mykola Mamenko
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston, Houston, Texas; and
| | - Vivek Bhalla
- Division of Nephrology, Department of Medicine, Stanford University, Stanford, California
| | - Oleh Pochynyuk
- Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center at Houston, Houston, Texas; and
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25
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Zaika O, Palygin O, Tomilin V, Mamenko M, Staruschenko A, Pochynyuk O. Insulin and IGF-1 activate Kir4.1/5.1 channels in cortical collecting duct principal cells to control basolateral membrane voltage. Am J Physiol Renal Physiol 2016; 310:F311-21. [PMID: 26632606 PMCID: PMC4839479 DOI: 10.1152/ajprenal.00436.2015] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Accepted: 11/30/2015] [Indexed: 01/12/2023] Open
Abstract
Potassium Kir4.1/5.1 channels are abundantly expressed at the basolateral membrane of principal cells in the cortical collecting duct (CCD), where they are thought to modulate transport rates by controlling transepithelial voltage. Insulin and insulin-like growth factor-1 (IGF-1) stimulate apically localized epithelial sodium channels (ENaC) to augment sodium reabsorption in the CCD. However, little is known about their actions on potassium channels localized at the basolateral membrane. In this study, we implemented patch-clamp analysis in freshly isolated murine CCD to assess the effect of these hormones on Kir4.1/5.1 at both single channel and cellular levels. We demonstrated that K(+)-selective conductance via Kir4.1/5.1 is the major contributor to the macroscopic current recorded from the basolateral side in principal cells. Acute treatment with 10 μM amiloride (ENaC blocker), 100 nM tertiapin-Q (TPNQ; ROMK inhibitor), and 100 μM ouabain (Na(+)-K(+)-ATPase blocker) failed to produce a measurable effect on the macroscopic current. In contrast, Kir4.1 inhibitor nortriptyline (100 μM), but not fluoxetine (100 μM), virtually abolished whole cell K(+)-selective conductance. Insulin (100 nM) markedly increased the open probability of Kir4.1/5.1 and nortriptyline-sensitive whole cell current, leading to significant hyperpolarization of the basolateral membrane. Inhibition of the phosphatidylinositol 3-kinase cascade with LY294002 (20 μM) abolished action of insulin on Kir4.1/5.1. IGF-1 had similar stimulatory actions on Kir4.1/5.1-mediated conductance only when applied at a higher (500 nM) concentration and was ineffective at 100 nM. We concluded that both insulin and, to a lesser extent, IGF-1 activate Kir4.1/5.1 channel activity and open probability to hyperpolarize the basolateral membrane, thereby facilitating Na(+) reabsorption in the CCD.
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Affiliation(s)
- Oleg Zaika
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston, Houston, Texas
| | - Oleg Palygin
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin; and
| | - Viktor Tomilin
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston, Houston, Texas; Institute of Cytology, Russian Academy of Sciences, St. Petersburg, Russian Federation
| | - Mykola Mamenko
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston, Houston, Texas
| | | | - Oleh Pochynyuk
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston, Houston, Texas;
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26
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Chen L, Tuo B, Dong H. Regulation of Intestinal Glucose Absorption by Ion Channels and Transporters. Nutrients 2016; 8:nu8010043. [PMID: 26784222 PMCID: PMC4728656 DOI: 10.3390/nu8010043] [Citation(s) in RCA: 99] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Revised: 12/18/2015] [Accepted: 01/06/2016] [Indexed: 12/14/2022] Open
Abstract
The absorption of glucose is electrogenic in the small intestinal epithelium. The major route for the transport of dietary glucose from intestinal lumen into enterocytes is the Na+/glucose cotransporter (SGLT1), although glucose transporter type 2 (GLUT2) may also play a role. The membrane potential of small intestinal epithelial cells (IEC) is important to regulate the activity of SGLT1. The maintenance of membrane potential mainly depends on the activities of cation channels and transporters. While the importance of SGLT1 in glucose absorption has been systemically studied in detail, little is currently known about the regulation of SGLT1 activity by cation channels and transporters. A growing line of evidence suggests that cytosolic calcium ([Ca2+]cyt) can regulate the absorption of glucose by adjusting GLUT2 and SGLT1. Moreover, the absorption of glucose and homeostasis of Ca2+ in IEC are regulated by cation channels and transporters, such as Ca2+ channels, K+ channels, Na+/Ca2+ exchangers, and Na+/H+ exchangers. In this review, we consider the involvement of these cation channels and transporters in the regulation of glucose uptake in the small intestine. Modulation of them may be a potential strategy for the management of obesity and diabetes.
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Affiliation(s)
- Lihong Chen
- Department of Gastroenterology, Affiliated Hospital, Zunyi Medical College, and Digestive Disease Institute of Guizhou Province, Zunyi 563003, China.
| | - Biguang Tuo
- Department of Gastroenterology, Affiliated Hospital, Zunyi Medical College, and Digestive Disease Institute of Guizhou Province, Zunyi 563003, China.
| | - Hui Dong
- Department of Gastroenterology, Affiliated Hospital, Zunyi Medical College, and Digestive Disease Institute of Guizhou Province, Zunyi 563003, China.
- Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China.
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Abstract
More than two dozen types of potassium channels, with different biophysical and regulatory properties, are expressed in the kidney, influencing renal function in many important ways. Recently, a confluence of discoveries in areas from human genetics to physiology, cell biology, and biophysics has cast light on the special function of five different potassium channels in the distal nephron, encoded by the genes KCNJ1, KCNJ10, KCNJ16, KCNMA1, and KCNN3. Research aimed at understanding how these channels work in health and go awry in disease has transformed our understanding of potassium balance and provided new insights into mechanisms of renal sodium handling and the maintenance of blood pressure. This review focuses on recent advances in this rapidly evolving field.
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Affiliation(s)
- Paul A Welling
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland 21201;
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28
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Pilmore E, Hamilton KL. The Role of MicroRNAs in the Regulation of K(+) Channels in Epithelial Tissue. Front Physiol 2015; 6:352. [PMID: 26648872 PMCID: PMC4664832 DOI: 10.3389/fphys.2015.00352] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Accepted: 11/09/2015] [Indexed: 12/27/2022] Open
Abstract
Our understanding of the modulation of proteins has shifted in direction with the discovery of microRNAs (miRs) over twenty years ago. MiRs are now in the “limelight” as these non-coding pieces of RNA (generally ~22 nucleotides long) result in altered translation and function of proteins. Indeed, miRs are now reported to be potential biomarkers of disease. Epithelial K+ channels play many roles in electrolyte and fluid homeostasis of the human body and have been suggested to be therapeutic targets of disease. Interestingly, the role of miRs in modulating K+ channels of epithelial tissues is only emerging now. This minireview focuses on recent novel findings into the role of miRs in the regulation of K+ channels of epithelia.
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Affiliation(s)
- Elliot Pilmore
- Department of Physiology, Otago School of Medical Sciences, University of Otago Dunedin, New Zealand
| | - Kirk L Hamilton
- Department of Physiology, Otago School of Medical Sciences, University of Otago Dunedin, New Zealand
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Proinflammatory Cytokines and Potassium Channels in the Kidney. Mediators Inflamm 2015; 2015:362768. [PMID: 26508816 PMCID: PMC4609835 DOI: 10.1155/2015/362768] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Accepted: 09/09/2015] [Indexed: 01/08/2023] Open
Abstract
Proinflammatory cytokines affect several cell functions via receptor-mediated processes. In the kidney, functions of transporters and ion channels along the nephron are also affected by some cytokines. Among these, alteration of activity of potassium ion (K(+)) channels induces changes in transepithelial transport of solutes and water in the kidney, since K(+) channels in tubule cells are indispensable for formation of membrane potential which serves as a driving force for the transepithelial transport. Altered K(+) channel activity may be involved in renal cell dysfunction during inflammation. Although little information was available regarding the effects of proinflammatory cytokines on renal K(+) channels, reports have emerged during the last decade. In human proximal tubule cells, interferon-γ showed a time-dependent biphasic effect on a 40 pS K(+) channel, that is, delayed suppression and acute stimulation, and interleukin-1β acutely suppressed the channel activity. Transforming growth factor-β1 activated KCa3.1 K(+) channel in immortalized human proximal tubule cells, which would be involved in the pathogenesis of renal fibrosis. This review discusses the effects of proinflammatory cytokines on renal K(+) channels and the causal relationship between the cytokine-induced changes in K(+) channel activity and renal dysfunction.
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30
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Labarca M, Nizar JM, Walczak EM, Dong W, Pao AC, Bhalla V. Harvest and primary culture of the murine aldosterone-sensitive distal nephron. Am J Physiol Renal Physiol 2015; 308:F1306-15. [PMID: 25810438 PMCID: PMC4451330 DOI: 10.1152/ajprenal.00668.2014] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Accepted: 03/19/2015] [Indexed: 11/22/2022] Open
Abstract
The aldosterone-sensitive distal nephron (ASDN) exhibits axial heterogeneity in structure and function from the distal convoluted tubule to the medullary collecting duct. Ion and water transport is primarily divided between the cortex and medulla of the ASDN, respectively. Transcellular transport in this segment is highly regulated in health and disease and is integrated across different cell types. We currently lack an inexpensive, high-yield, and tractable technique to harvest and culture cells for the study of gene expression and physiological properties of mouse cortical ASDN. To address this need, we harvested tubules bound to Dolichos biflorus agglutinin lectin-coated magnetic beads from the kidney cortex and characterized these cell preparations. We determined that these cells are enriched for markers of distal convoluted tubule, connecting tubule, and cortical collecting duct, including principal and intercalated cells. In primary culture, these cells develop polarized monolayers with high resistance (1,000-1,500 Ω * cm(2)) and maintain expression and activity of key channels. These cells demonstrate an amiloride-sensitive short-circuit current that can be enhanced with aldosterone and maintain measurable potassium and anion secretion. Our method can be easily adopted to study the biology of the ASDN and to investigate phenotypic differences between wild-type and transgenic mouse models.
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Affiliation(s)
- Mariana Labarca
- Division of Nephrology, Department of Medicine, Stanford University, Palo Alto, California; and
| | - Jonathan M Nizar
- Division of Nephrology, Department of Medicine, Stanford University, Palo Alto, California; and
| | - Elisabeth M Walczak
- Division of Nephrology, Department of Medicine, Stanford University, Palo Alto, California; and
| | - Wuxing Dong
- Division of Nephrology, Department of Medicine, Stanford University, Palo Alto, California; and
| | - Alan C Pao
- Division of Nephrology, Department of Medicine, Stanford University, Palo Alto, California; and Division of Nephrology, Department of Medicine, Veterans Affairs Palo Alto Healthcare System, Palo Alto, California
| | - Vivek Bhalla
- Division of Nephrology, Department of Medicine, Stanford University, Palo Alto, California; and
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31
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Arai E, Baba Y, Iwagawa T, Kuribayashi H, Mochizuki Y, Murakami A, Watanabe S. Ablation of Kcnj10 expression in retinal explants revealed pivotal roles for Kcnj10 in the proliferation and development of Müller glia. Mol Vis 2015; 21:148-59. [PMID: 25684980 PMCID: PMC4323724] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2014] [Accepted: 02/05/2015] [Indexed: 11/29/2022] Open
Abstract
PURPOSE We previously found that Kcnj10, an inwardly-rectifying potassium channel, is a gene expressed in c-kit-positive retinal progenitor cells on P1. The shRNA-mediated screening of the functions of the genes for retinal development in retinal explant culture suggested a role for Kcnj10 in the differentiation of 23Müller glia. In the present study, we extended the work and focused on analyzing the role of Kcnj10 in retinal development. METHODS shRNA-mediated downregulation of Kcnj10 in retinal explants and the in vivo mouse retina at the P1 stage was performed. Differentiation and proliferation of the retina were examined with immunohistochemistry. The effect of barium (Ba(2+)) treatment, which inhibits potassium currents by blocking potassium channels, on retinal development was examined. RESULTS When Kcnj10 was downregulated at E18, cellular proliferation and morphological differentiation were perturbed; in particular, a decreased number of Müller glial cells with abnormal morphological maturation was observed. The overexpression of Kcnj10 in retinal progenitors did not result in gross abnormality during retinal development, but rescued the abnormal differentiation induced with sh-Kcnj10. The presence of Ba(2+) in the retinal explant medium led to a phenotype similar to that seen with sh-Kcnj10. Ba(2+) exerts an effect mainly during late retinal development, and sh-Kcnj10 in the P1 retina affected Müller glia maturation, suggesting that Kcnj10 plays a pivotal role in the maturation of retinal cell subsets. A previous study of Kcnj10-knockout mice showed no obvious abnormality in retinal differentiation, especially of Müller glia. We examined the effects of the downregulation of Kcnj10 with in vivo electroporation of sh-Kcnj10 in the P1 retina. Retinal differentiation was perturbed, as seen following the in vitro downregulation of Kcnj10, suggesting that compensatory gene expression and/or signaling occurred in the Kcnj10-knockout mice in the retina, leading to normal eye development. CONCLUSION Kcnj10 plays a role in Müller glia maturation during retinal development probably through ionic channel activities.
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Affiliation(s)
- Eisuke Arai
- Division of Molecular and Developmental Biology, Institute of Medical Science, University of Tokyo, Tokyo, Japan,Department of Ophthalmology, Juntendo University School of Medicine, Tokyo, Japan
| | - Yukihiro Baba
- Division of Molecular and Developmental Biology, Institute of Medical Science, University of Tokyo, Tokyo, Japan
| | - Toshiro Iwagawa
- Division of Molecular and Developmental Biology, Institute of Medical Science, University of Tokyo, Tokyo, Japan
| | - Hiroshi Kuribayashi
- Division of Molecular and Developmental Biology, Institute of Medical Science, University of Tokyo, Tokyo, Japan
| | - Yujin Mochizuki
- Department of Ophthalmology, Juntendo University School of Medicine, Tokyo, Japan
| | - Akira Murakami
- Department of Ophthalmology, Juntendo University School of Medicine, Tokyo, Japan
| | - Sumiko Watanabe
- Division of Molecular and Developmental Biology, Institute of Medical Science, University of Tokyo, Tokyo, Japan
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Carrisoza-Gaytán R, Salvador C, Diaz-Bello B, Escobar LI. Differential expression of the Kv1 voltage-gated potassium channel family in the rat nephron. J Mol Histol 2014; 45:583-97. [PMID: 24948003 DOI: 10.1007/s10735-014-9581-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2014] [Accepted: 06/11/2014] [Indexed: 11/25/2022]
Abstract
Several potassium (K(+)) channels contribute to maintaining the resting membrane potential of renal epithelial cells. Apart from buffering the cell membrane potential and cell volume, K(+) channels allow sodium reabsorption in the proximal tubule (PT), K(+) recycling and K(+) reabsorption in the thick ascending limb (TAL) and K(+) secretion and K(+) reabsorption in the distal convoluted tubule (DCT), connecting tubule (CNT) and collecting duct. Previously, we identified Kv.1.1, Kv1.3 and Kv1.6 channels in collecting ducts of the rat inner medulla. We also detected intracellular Kv1.3 channel in the acid secretory intercalated cells, which is trafficked to the apical membrane in response to dietary K(+) to function as a secretory K(+) channel. In this work we sought to characterize the expression of all members of the Kv1 family in the rat nephron. mRNA and protein expression were detected for all Kv1 channels. Immunoblots identified differential expression of each Kv1 in the cortex, outer and inner medulla. Immunofluorescence labeling detected Kv1.5 in Bowman´s capsule and endothelial cells and Kv1.7 in podocytes, endothelial cells and macula densa in glomeruli; Kv1.4, Kv1.5 and Kv1.7 in PT; Kv1.2, Kv1.4 and Kv1.6 in TAL; Kv1.1, Kv1.4 and Kv1.6 in DCT and CNT and Kv1.3 in DCT, and all the Kv1 family in the cortical and medullary collecting ducts. Recently, some hereditary renal syndromes have been attributed to mutations in K(+) channels. Our results expand the repertoire of K(+) channels that contribute to K(+) homeostasis to include the Kv1 family.
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Affiliation(s)
- Rolando Carrisoza-Gaytán
- Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México, 04510, México, DF, Mexico
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Abstract
The distal convoluted tubule is the nephron segment that lies immediately downstream of the macula densa. Although short in length, the distal convoluted tubule plays a critical role in sodium, potassium, and divalent cation homeostasis. Recent genetic and physiologic studies have greatly expanded our understanding of how the distal convoluted tubule regulates these processes at the molecular level. This article provides an update on the distal convoluted tubule, highlighting concepts and pathophysiology relevant to clinical practice.
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Affiliation(s)
- Arohan R Subramanya
- Departments of Medicine and Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania; Veterans Affairs Pittsburgh Healthcare System, Pittsburgh, Pennsylvania;
| | - David H Ellison
- Departments of Medicine and Physiology and Pharmacology, Oregon Health and Science University, Portland, Oregon; and Portland Veterans Affairs Medical Center, Portland, Oregon
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Hanssen O, Castermans E, Bovy C, Weekers L, Erpicum P, Dubois B, Bours V, Krzesinski JM, Jouret F. Two novel mutations of the CLDN16 gene cause familial hypomagnesaemia with hypercalciuria and nephrocalcinosis. Clin Kidney J 2014; 7:282-5. [PMID: 25852890 PMCID: PMC4377742 DOI: 10.1093/ckj/sfu019] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2014] [Accepted: 02/18/2014] [Indexed: 11/21/2022] Open
Abstract
Familial hypomagnesaemia with hypercalciuria and nephrocalcinosis is an autosomal-recessive disease caused by mutations in the CLDN16 or CLDN19 genes, which encode tight junction-associated proteins, claudin-16 and -19. The resultant tubulopathy leads to urinary loss of Mg2+ and Ca2+, with subsequent nephrocalcinosis and end-stage renal disease (ESRD). An 18-year-old boy presented with chronic kidney disease and proteinuria, as well as hypomagnesaemia, hypercalciuria and nephrocalcinosis. A kidney biopsy revealed tubular atrophy, interstitial fibrosis and segmental sclerosis of some glomeruli. Two novel mutations in the CLDN16 gene were identified: c.340C>T (nonsense) and c.427+5G>A (splice site). The patient reached ESRD at 23 and benefited from kidney transplantation.
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Affiliation(s)
- Oriane Hanssen
- Division of Nephrology , University of Liege Hospital (ULg CHU) , Liege , Belgium
| | - Emilie Castermans
- Division of Genetics , University of Liege Hospital (ULg CHU) , Liege , Belgium
| | - Christophe Bovy
- Division of Nephrology , University of Liege Hospital (ULg CHU) , Liege , Belgium
| | - Laurent Weekers
- Division of Nephrology , University of Liege Hospital (ULg CHU) , Liege , Belgium
| | - Pauline Erpicum
- Division of Nephrology , University of Liege Hospital (ULg CHU) , Liege , Belgium
| | - Bernard Dubois
- Division of Nephrology , University of Liege Hospital (ULg CHU) , Liege , Belgium
| | - Vincent Bours
- Division of Genetics , University of Liege Hospital (ULg CHU) , Liege , Belgium
| | | | - François Jouret
- Division of Nephrology , University of Liege Hospital (ULg CHU) , Liege , Belgium
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Mistry HD, Kurlak LO, Whitley GS, Cartwright JE, Broughton Pipkin F, Tribe RM. Expression of voltage-dependent potassium channels in first trimester human placentae. Placenta 2014; 35:337-40. [PMID: 24646441 DOI: 10.1016/j.placenta.2014.02.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Revised: 02/18/2014] [Accepted: 02/20/2014] [Indexed: 11/24/2022]
Abstract
Potassium channel α-subunits encoded by KCNQ1-5 genes form voltage-dependent channels (KV7), modulated by KCNE1-5 encoded accessory proteins. The aim was to determine KCNQ and KCNE mRNA expression and assess protein expression/localisation of the KCNQ3 and KCNE5 isoforms in first trimester placental tissue. Placentae were obtained from women undergoing elective surgical termination of pregnancy (TOP) at ≤ 10 weeks' (early TOP) and >10 weeks' (mid TOP) gestations. KCNQ1-5 expression was unchanged during the first trimester. KCNE5 expression increased in mid TOP vs. early TOP samples (P = 0.022). This novel study reports mRNA and protein expression of KV7 channels in first trimester placentae.
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Affiliation(s)
- H D Mistry
- Division of Women's Health, King's College London, Women's Health Academic Centre, KHP, St Thomas' Hospital, Westminster Bridge Road, London SE1 7EH, UK; Department of Nephrology, Hypertension, Clinical Pharmacology and of Clinical Research, University of Bern, Berne CH-3010, Switzerland.
| | - L O Kurlak
- Department of Obstetrics & Gynaecology, School of Medicine, University of Nottingham, Nottingham NG5 1PB, UK
| | - G S Whitley
- Division of Biomedical Sciences, St George's University of London, London SW17 0RE, UK
| | - J E Cartwright
- Division of Biomedical Sciences, St George's University of London, London SW17 0RE, UK
| | - F Broughton Pipkin
- Department of Obstetrics & Gynaecology, School of Medicine, University of Nottingham, Nottingham NG5 1PB, UK
| | - R M Tribe
- Division of Women's Health, King's College London, Women's Health Academic Centre, KHP, St Thomas' Hospital, Westminster Bridge Road, London SE1 7EH, UK
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Expression of the small conductance Ca²⁺-activated potassium channel subtype 3 (SK3) in rat uterus after stimulation with 17β-estradiol. PLoS One 2014; 9:e87652. [PMID: 24505302 PMCID: PMC3914860 DOI: 10.1371/journal.pone.0087652] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2013] [Accepted: 12/31/2013] [Indexed: 01/15/2023] Open
Abstract
Preterm births accounts for roughly 9% of all births worldwide and can have detrimental or even lethal consequences for the infant. However to develop new treatment that will lower the rate of preterm births, more knowledge is required on the factors contributing to the contraction and relaxation of the myometrium. The small conductance Ca2+-activated potassium channel subtype 3 (SK3) has been identified in the myometrium of several species including humans, mice and rats, but with great inter species variation of the expression pattern and regulation. The aim of this study was to investigate the expression of SK3 in the uterus of rats stimulated with 17β-estradiol and progesterone in order to get an in depth understanding of the rat uterine SK3. Using immunohistochemistry SK3 was localized to the glandular and luminal endometrial lamina epitheliali. Furthermore, a weak signal was observed in the myometrium. Using Western blot the protein level of SK3 was found to increase in uteri from animals treated with 17β-estradiol, an effect that was not reflected at the mRNA level. The levels of mRNA for SK3 were significantly lower in the uterus of 17β-estradiol-treated animals than in the uterus of ovariectomized animals. We conclude that the SK channels are present in the endometrial epithelium, and possibly also in the myometrium of the rat uterus. Furthermore, the hormonal effect on SK3 caused by 17β-estradiol includes divergent regulation at mRNA and protein levels.
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Girault A, Brochiero E. Evidence of K+ channel function in epithelial cell migration, proliferation, and repair. Am J Physiol Cell Physiol 2013; 306:C307-19. [PMID: 24196531 DOI: 10.1152/ajpcell.00226.2013] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Efficient repair of epithelial tissue, which is frequently exposed to insults, is necessary to maintain its functional integrity. It is therefore necessary to better understand the biological and molecular determinants of tissue regeneration and to develop new strategies to promote epithelial repair. Interestingly, a growing body of evidence indicates that many members of the large and widely expressed family of K(+) channels are involved in regulation of cell migration and proliferation, key processes of epithelial repair. First, we briefly summarize the complex mechanisms, including cell migration, proliferation, and differentiation, engaged after epithelial injury. We then present evidence implicating K(+) channels in the regulation of these key repair processes. We also describe the mechanisms whereby K(+) channels may control epithelial repair processes. In particular, changes in membrane potential, K(+) concentration, cell volume, intracellular Ca(2+), and signaling pathways following modulation of K(+) channel activity, as well as physical interaction of K(+) channels with the cytoskeleton or integrins are presented. Finally, we discuss the challenges to efficient, specific, and safe targeting of K(+) channels for therapeutic applications to improve epithelial repair in vivo.
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Affiliation(s)
- Alban Girault
- Centre de Recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), Montreal, Quebec, Canada; and
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38
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Zaika OL, Mamenko M, Palygin O, Boukelmoune N, Staruschenko A, Pochynyuk O. Direct inhibition of basolateral Kir4.1/5.1 and Kir4.1 channels in the cortical collecting duct by dopamine. Am J Physiol Renal Physiol 2013; 305:F1277-87. [PMID: 23986512 PMCID: PMC3840222 DOI: 10.1152/ajprenal.00363.2013] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Accepted: 08/16/2013] [Indexed: 12/11/2022] Open
Abstract
It is recognized that dopamine promotes natriuresis by inhibiting multiple transporting systems in the proximal tubule. In contrast, less is known about the molecular targets of dopamine actions on water-electrolyte transport in the cortical collecting duct (CCD). Epithelial cells in the CCD are exposed to dopamine, which is synthesized locally or secreted from sympathetic nerve endings. Basolateral K(+) channels in the distal renal tubule are critical for K(+) recycling and controlling basolateral membrane potential to establish the driving force for Na(+) reabsorption. Here, we demonstrate that Kir4.1 and Kir5.1 are highly expressed in the mouse kidney cortex and are localized to the basolateral membrane of the CCD. Using patch-clamp electrophysiology in freshly isolated CCDs, we detected highly abundant 40-pS and scarce 20-pS single channel conductances, most likely representing Kir4.1/5.1 and Kir4.1 channels, respectively. Dopamine reversibly decreased the open probability of both channels, with a relatively greater action on the Kir4.1/5.1 heterodimer. This effect was mediated by D2-like but not D1-like dopamine receptors. PKC blockade abolished the inhibition of basolateral K(+) channels by dopamine. Importantly, dopamine significantly decreased the amplitude of Kir4.1/5.1 and Kir4.1 unitary currents. Consistently, dopamine induced an acute depolarization of basolateral membrane potential, as directly monitored using current-clamp mode in isolated CCDs. Therefore, we demonstrate that dopamine inhibits basolateral Kir4.1/5.1 and Kir4.1 channels in CCD cells via stimulation of D2-like receptors and subsequently PKC. This leads to depolarization of the basolateral membrane and a decreased driving force for Na(+) reabsorption in the distal renal tubule.
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Affiliation(s)
- Oleg L Zaika
- Dept. of Integrative Biology and Pharmacology, Univ. of Texas Health Science Center, 6431 Fannin St., Houston, TX 77030.
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Nakamura K, Komagiri Y, Kubokawa M. Interleukin-1β suppresses activity of an inwardly rectifying K+ channel in human renal proximal tubule cells. J Physiol Sci 2013; 63:377-87. [PMID: 23797607 PMCID: PMC10717820 DOI: 10.1007/s12576-013-0275-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2013] [Accepted: 06/10/2013] [Indexed: 12/12/2022]
Abstract
We investigated the effect of interleukin-1β (IL-1β) on activity of an inwardly rectifying K+ channel in cultured human proximal tubule cells (RPTECs), using the patch-clamp technique and Fura-2 Ca2+ imaging. IL-1β (15 pg/ml) acutely reduced K+ channel activity in cell-attached patches. This effect was blocked by the IL-1 receptor antagonist (20 ng/ml), an inhibitor of phospholipase C, neomycin (300 μM), and an inhibitor of protein kinase C (PKC), GF109203X (500 nM). The Fura-2 Ca2+ imaging revealed that IL-1β increased intracellular Ca2+ concentration even after removal of extracellular Ca2+, which was blocked by an inhibitor of inositol 1,4,5-trisphosphate receptors, 2-aminoethoxydiphenyl borate (2-APB, 1 μM). Moreover, IL-1β suppressed channel activity in the presence of 2-APB without extracellular Ca2+. These results suggest that IL-1β suppresses K+ channel activity in RPTECs through binding to its specific receptor and activation of the PKC pathway even though intracellular Ca2+ does not increase.
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Affiliation(s)
- Kazuyoshi Nakamura
- Department of Physiology, Iwate Medical University School of Medicine, 2-1-1 Nishitokuta, Yahaba, 028-3694 Japan
| | - You Komagiri
- Department of Physiology, Iwate Medical University School of Medicine, 2-1-1 Nishitokuta, Yahaba, 028-3694 Japan
| | - Manabu Kubokawa
- Department of Physiology, Iwate Medical University School of Medicine, 2-1-1 Nishitokuta, Yahaba, 028-3694 Japan
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Sheikh IA, Koley H, Chakrabarti MK, Hoque KM. The Epac1 signaling pathway regulates Cl- secretion via modulation of apical KCNN4c channels in diarrhea. J Biol Chem 2013; 288:20404-15. [PMID: 23720748 DOI: 10.1074/jbc.m113.467860] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The apical membrane of intestinal epithelia expresses intermediate conductance K(+) channel (KCNN4), which provides the driving force for Cl(-) secretion. However, its role in diarrhea and regulation by Epac1 is unknown. Previously we have established that Epac1 upon binding of cAMP activates a PKA-independent mechanism of Cl(-) secretion via stimulation of Rap2-phospholipase Cε-[Ca(2+)]i signaling. Here we report that Epac1 regulates surface expression of KCNN4c channel through its downstream Rap1A-RhoA-Rho-associated kinase (ROCK) signaling pathway for sustained Cl(-) secretion. Depletion of Epac1 protein and apical addition of TRAM-34, a specific KCNN4 inhibitor, significantly abolished cAMP-stimulated Cl(-) secretion and apical K(+) conductance (IK(ap)) in T84WT cells. The current-voltage relationship of basolaterally permeabilized monolayers treated with Epac1 agonist 8-(4-chlorophenylthio)-2'-O- methyladenosine 3',5'-cyclic monophosphate showed the presence of an inwardly rectifying and TRAM-34-sensitive K(+) channel in T84WT cells that was absent in Epac1KDT84 cells. Reconstructed confocal images in Epac1KDT84 cells revealed redistribution of KCNN4c proteins into subapical intracellular compartment, and a biotinylation assay showed ∼83% lower surface expression of KCNN4c proteins compared with T84WT cells. Further investigation revealed that an Epac1 agonist activates Rap1 to facilitate IK(ap). Both RhoA inhibitor (GGTI298) and ROCK inhibitor (H1152) significantly reduced cAMP agonist-stimulated IK(ap), whereas the latter additionally reduced colocalization of KCNN4c with the apical membrane marker wheat germ agglutinin in T84WT cells. In vivo mouse ileal loop experiments showed reduced fluid accumulation by TRAM-34, GGTI298, or H1152 when injected together with cholera toxin into the loop. We conclude that Rap1A-dependent signaling of Epac1 involving RhoA-ROCK is an important regulator of intestinal fluid transport via modulation of apical KCNN4c channels, a finding with potential therapeutic value in diarrheal diseases.
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Affiliation(s)
- Irshad Ali Sheikh
- Division of Molecular Pathophysiology, National Institute of Cholera and Enteric Diseases, P-33 CIT Road, Scheme-XM, Beliaghata, Kolkata 700010, India
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