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Schreiber R, Ousingsawat J, Kunzelmann K. The anoctamins: Structure and function. Cell Calcium 2024; 120:102885. [PMID: 38642428 DOI: 10.1016/j.ceca.2024.102885] [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: 02/21/2024] [Revised: 04/03/2024] [Accepted: 04/04/2024] [Indexed: 04/22/2024]
Abstract
When activated by increase in intracellular Ca2+, anoctamins (TMEM16 proteins) operate as phospholipid scramblases and as ion channels. Anoctamin 1 (ANO1) is the Ca2+-activated epithelial anion-selective channel that is coexpressed together with the abundant scramblase ANO6 and additional intracellular anoctamins. In salivary and pancreatic glands, ANO1 is tightly packed in the apical membrane and secretes Cl-. Epithelia of airways and gut use cystic fibrosis transmembrane conductance regulator (CFTR) as an apical Cl- exit pathway while ANO1 supports Cl- secretion mainly by facilitating activation of luminal CFTR and basolateral K+ channels. Under healthy conditions ANO1 modulates intracellular Ca2+ signals by tethering the endoplasmic reticulum, and except of glands its direct secretory contribution as Cl- channel might be small, compared to CFTR. In the kidneys ANO1 supports proximal tubular acid secretion and protein reabsorption and probably helps to excrete HCO3-in the collecting duct epithelium. However, under pathological conditions as in polycystic kidney disease, ANO1 is strongly upregulated and may cause enhanced proliferation and cyst growth. Under pathological condition, ANO1 and ANO6 are upregulated and operate as secretory channel/phospholipid scramblases, partly by supporting Ca2+-dependent processes. Much less is known about the role of other epithelial anoctamins whose potential functions are discussed in this review.
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Affiliation(s)
- Rainer Schreiber
- 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
| | - Karl Kunzelmann
- Physiological Institute, University of Regensburg, University street 31, D-93053 Regensburg, Germany.
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2
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Wu M, Chen JH. CFTR dysfunction leads to defective bacterial eradication on cystic fibrosis airways. Front Physiol 2024; 15:1385661. [PMID: 38699141 PMCID: PMC11063615 DOI: 10.3389/fphys.2024.1385661] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2024] [Accepted: 04/04/2024] [Indexed: 05/05/2024] Open
Abstract
Dysfunction of the cystic fibrosis transmembrane conductance regulator (CFTR) anion channel by genetic mutations causes the inherited disease cystic fibrosis (CF). CF lung disease that involves multiple disorders of epithelial function likely results from loss of CFTR function as an anion channel conducting chloride and bicarbonate ions and its function as a cellular regulator modulating the activity of membrane and cytosol proteins. In the absence of CFTR activity, abundant mucus accumulation, bacterial infection and inflammation characterize CF airways, in which inflammation-associated tissue remodeling and damage gradually destroys the lung. Deciphering the link between CFTR dysfunction and bacterial infection in CF airways may reveal the pathogenesis of CF lung disease and guide the development of new treatments. Research efforts towards this goal, including high salt, low volume, airway surface liquid acidosis and abnormal mucus hypotheses are critically reviewed.
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Affiliation(s)
| | - Jeng-Haur Chen
- College of Life Sciences, Zhejiang Normal University, Jinhua, Zhejiang, China
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Holmberg SR, Sakamoto Y, Kato A, Romero MF. The role of Na +-coupled bicarbonate transporters (NCBT) in health and disease. Pflugers Arch 2024; 476:479-503. [PMID: 38536494 DOI: 10.1007/s00424-024-02937-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: 12/15/2023] [Revised: 02/26/2024] [Accepted: 02/27/2024] [Indexed: 04/11/2024]
Abstract
Cellular and organism survival depends upon the regulation of pH, which is regulated by highly specialized cell membrane transporters, the solute carriers (SLC) (For a comprehensive list of the solute carrier family members, see: https://www.bioparadigms.org/slc/ ). The SLC4 family of bicarbonate (HCO3-) transporters consists of ten members, sorted by their coupling to either sodium (NBCe1, NBCe2, NBCn1, NBCn2, NDCBE), chloride (AE1, AE2, AE3), or borate (BTR1). The ionic coupling of SLC4A9 (AE4) remains controversial. These SLC4 bicarbonate transporters may be controlled by cellular ionic gradients, cellular membrane voltage, and signaling molecules to maintain critical cellular and systemic pH (acid-base) balance. There are profound consequences when blood pH deviates even a small amount outside the normal range (7.35-7.45). Chiefly, Na+-coupled bicarbonate transporters (NCBT) control intracellular pH in nearly every living cell, maintaining the biological pH required for life. Additionally, NCBTs have important roles to regulate cell volume and maintain salt balance as well as absorption and secretion of acid-base equivalents. Due to their varied tissue expression, NCBTs have roles in pathophysiology, which become apparent in physiologic responses when their expression is reduced or genetically deleted. Variations in physiological pH are seen in a wide variety of conditions, from canonically acid-base related conditions to pathologies not necessarily associated with acid-base dysfunction such as cancer, glaucoma, or various neurological diseases. The membranous location of the SLC4 transporters as well as recent advances in discovering their structural biology makes them accessible and attractive as a druggable target in a disease context. The role of sodium-coupled bicarbonate transporters in such a large array of conditions illustrates the potential of treating a wide range of disease states by modifying function of these transporters, whether that be through inhibition or enhancement.
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Affiliation(s)
- Shannon R Holmberg
- Physiology & Biomedical Engineering, Mayo Clinic College of Medicine & Science, 200 1st Street SW, Rochester, MN 55905, USA
- Biochemistry & Molecular Biology, Mayo Clinic College of Medicine & Science, 200 1st Street SW, Rochester, MN, USA
| | - Yohei Sakamoto
- School of Life Science and Technology, Tokyo Institute of Technology, Midori-Ku, Yokohama, 226-8501, Japan
| | - Akira Kato
- School of Life Science and Technology, Tokyo Institute of Technology, Midori-Ku, Yokohama, 226-8501, Japan
| | - Michael F Romero
- Physiology & Biomedical Engineering, Mayo Clinic College of Medicine & Science, 200 1st Street SW, Rochester, MN 55905, USA.
- Nephrology & Hypertension, Mayo Clinic College of Medicine & Science, 200 1st Street SW, Rochester, MN, USA.
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Bannier-Hélaouët M, Korving J, Ma Z, Begthel H, Giladi A, Lamers MM, van de Wetering WJ, Yawata N, Yawata M, LaPointe VLS, Dickman MM, Kalmann R, Imhoff SM, van Es JH, López-Iglesias C, Peters PJ, Haagmans BL, Wu W, Clevers H. Human conjunctiva organoids to study ocular surface homeostasis and disease. Cell Stem Cell 2024; 31:227-243.e12. [PMID: 38215738 DOI: 10.1016/j.stem.2023.12.008] [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: 07/11/2023] [Revised: 09/14/2023] [Accepted: 12/11/2023] [Indexed: 01/14/2024]
Abstract
The conjunctival epithelium covering the eye contains two main cell types: mucus-producing goblet cells and water-secreting keratinocytes, which present mucins on their apical surface. Here, we describe long-term expanding organoids and air-liquid interface representing mouse and human conjunctiva. A single-cell RNA expression atlas of primary and cultured human conjunctiva reveals that keratinocytes express multiple antimicrobial peptides and identifies conjunctival tuft cells. IL-4/-13 exposure increases goblet and tuft cell differentiation and drastically modifies the conjunctiva secretome. Human NGFR+ basal cells are identified as bipotent conjunctiva stem cells. Conjunctival cultures can be infected by herpes simplex virus 1 (HSV1), human adenovirus 8 (hAdV8), and SARS-CoV-2. HSV1 infection was reversed by acyclovir addition, whereas hAdV8 infection, which lacks an approved drug therapy, was inhibited by cidofovir. We document transcriptional programs induced by HSV1 and hAdV8. Finally, conjunctival organoids can be transplanted. Together, human conjunctiva organoid cultures enable the study of conjunctival (patho)-physiology.
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Affiliation(s)
- Marie Bannier-Hélaouët
- Hubrecht Institute, Royal Netherlands Academy of Arts and Sciences (KNAW), University Medical Center, Utrecht, the Netherlands; Oncode Institute, Hubrecht Institute, Utrecht, the Netherlands.
| | - Jeroen Korving
- Hubrecht Institute, Royal Netherlands Academy of Arts and Sciences (KNAW), University Medical Center, Utrecht, the Netherlands
| | - Ziliang Ma
- Singapore Immunology Network (SIgN), Agency for Science, Technology and Research (A(∗)STAR), and Department of Pharmacy, National University of Singapore, Singapore, Singapore
| | - Harry Begthel
- Hubrecht Institute, Royal Netherlands Academy of Arts and Sciences (KNAW), University Medical Center, Utrecht, the Netherlands; Oncode Institute, Hubrecht Institute, Utrecht, the Netherlands
| | - Amir Giladi
- Hubrecht Institute, Royal Netherlands Academy of Arts and Sciences (KNAW), University Medical Center, Utrecht, the Netherlands; Oncode Institute, Hubrecht Institute, Utrecht, the Netherlands
| | - Mart M Lamers
- Viroscience Department, Erasmus University Medical Center, Rotterdam, the Netherlands
| | - Willine J van de Wetering
- Maastricht Multimodal Molecular Imaging Institute, Maastricht University, Maastricht, the Netherlands
| | - Nobuyo Yawata
- Department of Ocular Pathology and Imaging Science, Kyushu University, Fukuoka, Japan; Singapore Eye Research Institute, Singapore, Singapore; Ophthalmology and Visual Sciences Academic Clinical Program, Duke-NUS Medical School, Singapore, Singapore
| | - Makoto Yawata
- Department of Pediatrics, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore; National University Health System, Singapore, Singapore; Immunology Program, Life Sciences Institute, National University of Singapore, Singapore, Singapore; NUSMED Immunology Translational Research Program, National University of Singapore, Singapore, Singapore; Singapore Institute for Clinical Sciences (SICS), Agency for Science, Technology and Research (A(∗)STAR), Singapore, Singapore; International Research Center for Medical Sciences, Kumamoto University, Kumamoto, Japan
| | - Vanessa L S LaPointe
- Department of Cell Biology-Inspired Tissue Engineering, MERLN Institute for Technology-Inspired Regenerative Medicine, Maastricht, the Netherlands
| | - Mor M Dickman
- Department of Cell Biology-Inspired Tissue Engineering, MERLN Institute for Technology-Inspired Regenerative Medicine, Maastricht, the Netherlands; University Eye Clinic Maastricht, Maastricht University Medical Center, Maastricht, the Netherlands
| | - Rachel Kalmann
- Department of Ophthalmology, University Medical Center, Utrecht, the Netherlands
| | - Saskia M Imhoff
- Department of Ophthalmology, University Medical Center, Utrecht, the Netherlands
| | - Johan H van Es
- Hubrecht Institute, Royal Netherlands Academy of Arts and Sciences (KNAW), University Medical Center, Utrecht, the Netherlands; Oncode Institute, Hubrecht Institute, Utrecht, the Netherlands
| | - Carmen López-Iglesias
- Maastricht Multimodal Molecular Imaging Institute, Maastricht University, Maastricht, the Netherlands
| | - Peter J Peters
- Maastricht Multimodal Molecular Imaging Institute, Maastricht University, Maastricht, the Netherlands
| | - Bart L Haagmans
- Viroscience Department, Erasmus University Medical Center, Rotterdam, the Netherlands
| | - Wei Wu
- Singapore Immunology Network (SIgN), Agency for Science, Technology and Research (A(∗)STAR), and Department of Pharmacy, National University of Singapore, Singapore, Singapore
| | - Hans Clevers
- Hubrecht Institute, Royal Netherlands Academy of Arts and Sciences (KNAW), University Medical Center, Utrecht, the Netherlands; Oncode Institute, Hubrecht Institute, Utrecht, the Netherlands.
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Rehman T, Welsh MJ. Inflammation as a Regulator of the Airway Surface Liquid pH in Cystic Fibrosis. Cells 2023; 12:1104. [PMID: 37190013 PMCID: PMC10137218 DOI: 10.3390/cells12081104] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Revised: 04/05/2023] [Accepted: 04/06/2023] [Indexed: 05/17/2023] Open
Abstract
The airway surface liquid (ASL) is a thin sheet of fluid that covers the luminal aspect of the airway epithelium. The ASL is a site of several first-line host defenses, and its composition is a key factor that determines respiratory fitness. Specifically, the acid-base balance of ASL has a major influence on the vital respiratory defense processes of mucociliary clearance and antimicrobial peptide activity against inhaled pathogens. In the inherited disorder cystic fibrosis (CF), loss of cystic fibrosis transmembrane conductance regulator (CFTR) anion channel function reduces HCO3- secretion, lowers the pH of ASL (pHASL), and impairs host defenses. These abnormalities initiate a pathologic process whose hallmarks are chronic infection, inflammation, mucus obstruction, and bronchiectasis. Inflammation is particularly relevant as it develops early in CF and persists despite highly effective CFTR modulator therapy. Recent studies show that inflammation may alter HCO3- and H+ secretion across the airway epithelia and thus regulate pHASL. Moreover, inflammation may enhance the restoration of CFTR channel function in CF epithelia exposed to clinically approved modulators. This review focuses on the complex relationships between acid-base secretion, airway inflammation, pHASL regulation, and therapeutic responses to CFTR modulators. These factors have important implications for defining optimal ways of tackling CF airway inflammation in the post-modulator era.
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Affiliation(s)
- Tayyab Rehman
- Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109, USA
| | - Michael J. Welsh
- Departments of Internal Medicine and Molecular Physiology and Biophysics, Pappajohn Biomedical Institute, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
- Howard Hughes Medical Institute, University of Iowa, Iowa City, IA 52242, USA
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The mechanisms of chromogranin B-regulated Cl- homeostasis. Biochem Soc Trans 2022; 50:1659-1672. [PMID: 36511243 DOI: 10.1042/bst20220435] [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: 10/03/2022] [Revised: 11/25/2022] [Accepted: 12/01/2022] [Indexed: 12/15/2022]
Abstract
Chloride is the most abundant inorganic anions in almost all cells and in human circulation systems. Its homeostasis is therefore important for systems physiology and normal cellular activities. This topic has been extensively studied with chloride loaders and extruders expressed in both cell surfaces and intracellular membranes. With the newly discovered, large-conductance, highly selective Cl- channel formed by membrane-bound chromogranin B (CHGB), which differs from all other known anion channels of conventional transmembrane topology, and is distributed in plasma membranes, endomembrane systems, endosomal, and endolysosomal compartments in cells expressing it, we will discuss the potential physiological importance of the CHGB channels to Cl- homeostasis, cellular excitability and volume control, and cation uptake or release at the cellular and subcellular levels. These considerations and CHGB's association with human diseases make the CHGB channel a possible druggable target for future molecular therapeutics.
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