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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Kunzelmann K, Ousingsawat J, Kraus A, Park JH, Marquardt T, Schreiber R, Buchholz B. Pathogenic Relationships in Cystic Fibrosis and Renal Diseases: CFTR, SLC26A9 and Anoctamins. Int J Mol Sci 2023; 24:13278. [PMID: 37686084 PMCID: PMC10487509 DOI: 10.3390/ijms241713278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Revised: 07/31/2023] [Accepted: 08/22/2023] [Indexed: 09/10/2023] Open
Abstract
The Cl--transporting proteins CFTR, SLC26A9, and anoctamin (ANO1; ANO6) appear to have more in common than initially suspected, as they all participate in the pathogenic process and clinical outcomes of airway and renal diseases. In the present review, we will therefore concentrate on recent findings concerning electrolyte transport in the airways and kidneys, and the role of CFTR, SLC26A9, and the anoctamins ANO1 and ANO6. Special emphasis will be placed on cystic fibrosis and asthma, as well as renal alkalosis and polycystic kidney disease. In essence, we will summarize recent evidence indicating that CFTR is the only relevant secretory Cl- channel in airways under basal (nonstimulated) conditions and after stimulation by secretagogues. Information is provided on the expressions of ANO1 and ANO6, which are important for the correct expression and function of CFTR. In addition, there is evidence that the Cl- transporter SLC26A9 expressed in the airways may have a reabsorptive rather than a Cl--secretory function. In the renal collecting ducts, bicarbonate secretion occurs through a synergistic action of CFTR and the Cl-/HCO3- transporter SLC26A4 (pendrin), which is probably supported by ANO1. Finally, in autosomal dominant polycystic kidney disease (ADPKD), the secretory function of CFTR in renal cyst formation may have been overestimated, whereas ANO1 and ANO6 have now been shown to be crucial in ADPKD and therefore represent new pharmacological targets for the treatment of polycystic kidney disease.
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Affiliation(s)
- Karl Kunzelmann
- Physiological Institute, University of Regensburg, University Street 31, 93053 Regensburg, Germany; (J.O.); (R.S.)
| | - Jiraporn Ousingsawat
- Physiological Institute, University of Regensburg, University Street 31, 93053 Regensburg, Germany; (J.O.); (R.S.)
| | - Andre Kraus
- Department of Nephrology and Hypertension, Friedrich Alexander University Erlangen Nuremberg, 91054 Erlangen, Germany; (A.K.); (B.B.)
| | - Julien H. Park
- Department of Pediatrics, University Hospital Münster, 48149 Münster, Germany; (J.H.P.); (T.M.)
| | - Thorsten Marquardt
- Department of Pediatrics, University Hospital Münster, 48149 Münster, Germany; (J.H.P.); (T.M.)
| | - Rainer Schreiber
- Physiological Institute, University of Regensburg, University Street 31, 93053 Regensburg, Germany; (J.O.); (R.S.)
| | - Björn Buchholz
- Department of Nephrology and Hypertension, Friedrich Alexander University Erlangen Nuremberg, 91054 Erlangen, Germany; (A.K.); (B.B.)
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Márquez-Nogueras KM, Vuchkovska V, Kuo IY. Calcium Signaling in Polycystic Kidney Disease- cell death and survival. Cell Calcium 2023; 112:102733. [PMID: 37023534 DOI: 10.1016/j.ceca.2023.102733] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 03/20/2023] [Accepted: 03/30/2023] [Indexed: 04/03/2023]
Abstract
Polycystic kidney disease is typified by cysts in the kidney and extra-renal manifestations including hypertension and heart failure. The main genetic underpinning this disease are loss-of function mutations to the two polycystin proteins, polycystin 1 and polycystin 2. Molecularly, the disease is characterized by changes in multiple signaling pathways including down regulation of calcium signaling, which, in part, is contributed by the calcium permeant properties of polycystin 2. These signaling pathways enable the cystic cells to survive and avoid cell death. This review focuses on the studies that have emerged in the past 5 years describing how the structural insights gained from PC-1 and PC-2 inform the calcium dependent molecular pathways of autophagy and the unfolded protein response that are regulated by the polycystin proteins and how it leads to cell survival and/or cell death.
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Hegyi P, Seidler U, Kunzelmann K. CFTR-beyond the airways: Recent findings on the role of the CFTR channel in the pancreas, the intestine and the kidneys. J Cyst Fibros 2023; 22 Suppl 1:S17-S22. [PMID: 36621373 DOI: 10.1016/j.jcf.2022.12.017] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 12/31/2022] [Accepted: 12/31/2022] [Indexed: 01/09/2023]
Abstract
With increased longevity of patients suffering from cystic fibrosis, and widespread lung transplantation facilities, the sequelae of defective CFTR in other organs than the airways come to the fore. This minireview highlights recent scientific progress in the understanding of CFTR function in the pancreas, the intestine and the kidney, and explores potential therapeutic strategies to combat defective CFTR function in these organs.
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Affiliation(s)
- Peter Hegyi
- Institute for Translational Medicine, Medical School, University of Pécs, 7624 Pécs, Hungary; Center for Translational Medicine and Institute of Pancreatic Diseases, Semmelweis University, 1085 Budapest, Hungary; Translational Pancreatology Research Group, Interdisciplinary Centre of Excellence for Research Development and Innovation, University of Szeged, 6725 Szeged, Hungary
| | - Ursula Seidler
- Department of Gastroenterology, Hannover Medical School, 30625 Hannover, Germany.
| | - Karl Kunzelmann
- Institute of Physiology, Regensburg University, 93040 Regensburg, Germany
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Tamma G. The Electrogenic Chloride Exchanger ClC5 as a Novel Player in Renal Cysts in Tuberous Sclerosis. Am J Pathol 2023; 193:136-7. [PMID: 36481196 DOI: 10.1016/j.ajpath.2022.11.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Accepted: 11/30/2022] [Indexed: 12/12/2022]
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Choudhury MI, Benson MA, Sun SX. Trans-epithelial fluid flow and mechanics of epithelial morphogenesis. Semin Cell Dev Biol 2022; 131:146-159. [PMID: 35659163 DOI: 10.1016/j.semcdb.2022.05.020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Revised: 05/22/2022] [Accepted: 05/23/2022] [Indexed: 12/14/2022]
Abstract
Active fluid transport across epithelial monolayers is emerging as a major driving force of tissue morphogenesis in a variety of healthy and diseased systems, as well as during embryonic development. Cells use directional transport of ions and osmotic gradients to drive fluid flow across the cell surface, in the process also building up fluid pressure. The basic physics of this process is described by the osmotic engine model, which also underlies actin-independent cell migration. Recently, the trans-epithelial fluid flux and the hydraulic pressure gradient have been explicitly measured for a variety of cellular and tissue model systems across various species. For the kidney, it was shown that tubular epithelial cells behave as active mechanical fluid pumps: the trans-epithelial fluid flux depends on the hydraulic pressure difference across the epithelial layer. When a stall pressure is reached, the fluid flux vanishes. Hydraulic forces generated from active fluid pumping are important in tissue morphogenesis and homeostasis, and could also underlie multiple morphogenic events seen in other developmental contexts. In this review, we highlight findings that examined the role of trans-epithelial fluid flux and hydraulic pressure gradient in driving tissue-scale morphogenesis. We also review organ pathophysiology due to impaired fluid pumping and the loss of hydraulic pressure sensing at the cellular scale. Finally, we draw an analogy between cellular fluidic pumps and a connected network of water pumps in a city. The dynamics of fluid transport in an active and adaptive network is determined globally at the systemic level, and transport in such a network is best when each pump is operating at its optimal efficiency.
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Affiliation(s)
- Mohammad Ikbal Choudhury
- Department of Mechanical Engineering, Johns Hopkins University, Baltimore, MD 21218, United States; Institute of NanoBioTechnology, Johns Hopkins University, Baltimore, MD 21218, United States; Department of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, United States
| | - Morgan A Benson
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD 21218, United States; Institute of NanoBioTechnology, Johns Hopkins University, Baltimore, MD 21218, United States
| | - Sean X Sun
- Department of Mechanical Engineering, Johns Hopkins University, Baltimore, MD 21218, United States; Institute of NanoBioTechnology, Johns Hopkins University, Baltimore, MD 21218, United States; Center for Cell Dynamics, Johns Hopkins University, Baltimore, MD 21218, United States.
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Zhou X, Torres VE. Emerging therapies for autosomal dominant polycystic kidney disease with a focus on cAMP signaling. Front Mol Biosci 2022; 9:981963. [PMID: 36120538 PMCID: PMC9478168 DOI: 10.3389/fmolb.2022.981963] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Accepted: 08/05/2022] [Indexed: 11/29/2022] Open
Abstract
Autosomal dominant polycystic kidney disease (ADPKD), with an estimated genetic prevalence between 1:400 and 1:1,000 individuals, is the third most common cause of end stage kidney disease after diabetes mellitus and hypertension. Over the last 3 decades there has been great progress in understanding its pathogenesis. This allows the stratification of therapeutic targets into four levels, gene mutation and polycystin disruption, proximal mechanisms directly caused by disruption of polycystin function, downstream regulatory and signaling pathways, and non-specific pathophysiologic processes shared by many other diseases. Dysfunction of the polycystins, encoded by the PKD genes, is closely associated with disruption of calcium and upregulation of cyclic AMP and protein kinase A (PKA) signaling, affecting most downstream regulatory, signaling, and pathophysiologic pathways altered in this disease. Interventions acting on G protein coupled receptors to inhibit of 3′,5′-cyclic adenosine monophosphate (cAMP) production have been effective in preclinical trials and have led to the first approved treatment for ADPKD. However, completely blocking cAMP mediated PKA activation is not feasible and PKA activation independently from cAMP can also occur in ADPKD. Therefore, targeting the cAMP/PKA/CREB pathway beyond cAMP production makes sense. Redundancy of mechanisms, numerous positive and negative feedback loops, and possibly counteracting effects may limit the effectiveness of targeting downstream pathways. Nevertheless, interventions targeting important regulatory, signaling and pathophysiologic pathways downstream from cAMP/PKA activation may provide additive or synergistic value and build on a strategy that has already had success. The purpose of this manuscript is to review the role of cAMP and PKA signaling and their multiple downstream pathways as potential targets for emergent therapies for ADPKD.
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Affiliation(s)
- Xia Zhou
- *Correspondence: Xia Zhou, ; Vicente E. Torres,
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Bichlmayer EM, Mahl L, Hesse L, Pion E, Haller V, Moehwald A, Hackl C, Werner JM, Schlitt HJ, Schwarz S, Kainz P, Brochhausen C, Groeger C, Steger F, Kölbl O, Daniel C, Amann K, Kraus A, Buchholz B, Aung T, Haerteis S. A 3D In Vivo Model for Studying Human Renal Cystic Tissue and Mouse Kidney Slices. Cells 2022; 11:cells11152269. [PMID: 35892566 PMCID: PMC9330914 DOI: 10.3390/cells11152269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 07/14/2022] [Accepted: 07/19/2022] [Indexed: 11/23/2022] Open
Abstract
(1) Background: Autosomal dominant polycystic kidney disease (ADPKD) is a frequent monogenic disorder that leads to progressive renal cyst growth and renal failure. Strategies to inhibit cyst growth in non-human cyst models have often failed in clinical trials. There is a significant need for models that enable studies of human cyst growth and drug trials. (2) Methods: Renal tissue from ADPKD patients who received a nephrectomy as well as adult mouse kidney slices were cultured on a chorioallantoic membrane (CAM) for one week. The cyst volume was monitored by microscopic and CT-based applications. The weight and angiogenesis were quantified. Morphometric and histological analyses were performed after the removal of the tissues from the CAM. (3) Results: The mouse and human renal tissue mostly remained vital for about one week on the CAM. The growth of cystic tissue was evaluated using microscopic and CT-based volume measurements, which correlated with weight and an increase in angiogenesis, and was accompanied by cyst cell proliferation. (4) Conclusions: The CAM model might bridge the gap between animal studies and clinical trials of human cyst growth, and provide a drug-testing platform for the inhibition of cyst enlargement. Real-time analyses of mouse kidney tissue may provide insights into renal physiology and reduce the need for animal experiments.
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Affiliation(s)
- Eva-Marie Bichlmayer
- Institute for Molecular and Cellular Anatomy, University of Regensburg, 93053 Regensburg, Germany; (E.-M.B.); (L.M.); (L.H.); (E.P.); (V.H.); (A.M.); (T.A.)
| | - Lina Mahl
- Institute for Molecular and Cellular Anatomy, University of Regensburg, 93053 Regensburg, Germany; (E.-M.B.); (L.M.); (L.H.); (E.P.); (V.H.); (A.M.); (T.A.)
| | - Leo Hesse
- Institute for Molecular and Cellular Anatomy, University of Regensburg, 93053 Regensburg, Germany; (E.-M.B.); (L.M.); (L.H.); (E.P.); (V.H.); (A.M.); (T.A.)
| | - Eric Pion
- Institute for Molecular and Cellular Anatomy, University of Regensburg, 93053 Regensburg, Germany; (E.-M.B.); (L.M.); (L.H.); (E.P.); (V.H.); (A.M.); (T.A.)
| | - Victoria Haller
- Institute for Molecular and Cellular Anatomy, University of Regensburg, 93053 Regensburg, Germany; (E.-M.B.); (L.M.); (L.H.); (E.P.); (V.H.); (A.M.); (T.A.)
| | - Andreas Moehwald
- Institute for Molecular and Cellular Anatomy, University of Regensburg, 93053 Regensburg, Germany; (E.-M.B.); (L.M.); (L.H.); (E.P.); (V.H.); (A.M.); (T.A.)
| | - Christina Hackl
- Department of Surgery, University Hospital Regensburg, Franz-Josef-Strauss-Allee 11, 93053 Regensburg, Germany; (C.H.); (J.M.W.); (H.J.S.)
| | - Jens M. Werner
- Department of Surgery, University Hospital Regensburg, Franz-Josef-Strauss-Allee 11, 93053 Regensburg, Germany; (C.H.); (J.M.W.); (H.J.S.)
| | - Hans J. Schlitt
- Department of Surgery, University Hospital Regensburg, Franz-Josef-Strauss-Allee 11, 93053 Regensburg, Germany; (C.H.); (J.M.W.); (H.J.S.)
| | | | - Philipp Kainz
- KML Vision GmbH, A-8020 Graz, Austria; (S.S.); (P.K.)
| | | | - Christian Groeger
- Department for Radiotherapy, University Hospital Regensburg, Franz-Josef-Strauss-Allee 11, 93053 Regensburg, Germany; (C.G.); (F.S.); (O.K.)
| | - Felix Steger
- Department for Radiotherapy, University Hospital Regensburg, Franz-Josef-Strauss-Allee 11, 93053 Regensburg, Germany; (C.G.); (F.S.); (O.K.)
| | - Oliver Kölbl
- Department for Radiotherapy, University Hospital Regensburg, Franz-Josef-Strauss-Allee 11, 93053 Regensburg, Germany; (C.G.); (F.S.); (O.K.)
| | - Christoph Daniel
- Department of Nephropathology, Friedrich-Alexander University Erlangen-Nürnberg, 91054 Erlangen, Germany; (C.D.); (K.A.)
| | - Kerstin Amann
- Department of Nephropathology, Friedrich-Alexander University Erlangen-Nürnberg, 91054 Erlangen, Germany; (C.D.); (K.A.)
| | - Andre Kraus
- Department of Nephrology and Hypertension, University Hospital Erlangen, University of Erlangen-Nuremberg, 91054 Erlangen, Germany; (A.K.); (B.B.)
| | - Björn Buchholz
- Department of Nephrology and Hypertension, University Hospital Erlangen, University of Erlangen-Nuremberg, 91054 Erlangen, Germany; (A.K.); (B.B.)
| | - Thiha Aung
- Institute for Molecular and Cellular Anatomy, University of Regensburg, 93053 Regensburg, Germany; (E.-M.B.); (L.M.); (L.H.); (E.P.); (V.H.); (A.M.); (T.A.)
- Faculty of Applied Healthcare Science, Deggendorf Institute of Technology, 94469 Deggendorf, Germany
| | - Silke Haerteis
- Institute for Molecular and Cellular Anatomy, University of Regensburg, 93053 Regensburg, Germany; (E.-M.B.); (L.M.); (L.H.); (E.P.); (V.H.); (A.M.); (T.A.)
- Correspondence:
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Abstract
Kidney organoids derived from human pluripotent stem cells constitute a novel model of disease, development, and regenerative therapy. Organoids are human, experimentally accessible, high throughput, and enable reconstitution of tissue-scale biology in a petri dish. Although gene expression patterns in organoid cells have been analyzed extensively, less is known about the functionality of these structures. Here, we review assays of physiological function in human kidney organoids, including best practices for quality control, and future applications. Tubular structures in organoids accumulate specific molecules through active transport, including dextran and organic anions, and swell with fluid in response to cAMP stimulation. When engrafted into animal models in vivo, organoids form vascularized glomerulus-like structures capable of size-selective filtration. Organoids exhibit metabolic, endocrine, injury, and infection phenotypes, although their specificity is not yet fully clear. To properly interpret organoid physiology assays, it is important to incorporate appropriate negative and positive controls, statistical methods, data presentation, molecular mechanisms, and clinical data sets. Improvements in organoid perfusion, patterning, and maturation are needed to enable branching morphogenesis, urine production, and renal replacement. Reconstituting renal physiology with kidney organoids is a new field with potential to provide fresh insights into classical phenomena.
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Affiliation(s)
- Benjamin S Freedman
- Division of Nephrology, Kidney Research Institute, and Institute for Stem Cell and Regenerative Medicine, Department of Medicine, Department of Laboratory Medicine and Physiology (adjunct), and Department of Bioengineering (adjunct), University of Washington School of Medicine, Seattle, Washington
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