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Zhang J, Lin L, Chen X, Wang S, Wei Y, Zhou W, Yang S, Zhou S. Conjunctival Fluid Secretion Impairment via CaCC-CFTR Dysfunction Is the Key Mechanism in Environmental Dry Eye. Int J Mol Sci 2022; 23:ijms232214399. [PMID: 36430877 PMCID: PMC9697764 DOI: 10.3390/ijms232214399] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Revised: 11/12/2022] [Accepted: 11/15/2022] [Indexed: 11/22/2022] Open
Abstract
Dry eye disease (DED) is a multifactorial disease with an incidence of approximately 50% worldwide. DED seriously affects quality of life and work. The prevalence of environmental DED (eDED) ranges from 35 to 48%. Conjunctival fluid secretion dysfunction may be one of the major causes of DED. Notably, the Cl- flux corresponds to the conjunctival fluid secretion and could be affected by ATP. Both the cystic fibrosis transmembrane conductance regulator (CFTR) and the Ca2+-activated Cl- channel (CaCC) are Cl- channels involved in epithelial fluid secretion. Conjunctival fluid secretion could be increased by activating P2Y2R (an ATP receptor) in DED. However, the role of the CaCC and CFTR channels regulated by P2Y2R in eDED remains unclear. In this study, we established a rabbit eDED model using a controlled drying system. A Ussing chamber was used to perform a conjunctival short-circuit current induced by ATP to evaluate the reactivity of the ion channels to the ATP. Our results revealed that eDED accompanied by conjunctival fluid secretion impairment was caused by a P2Y2R dysfunction, which is related to CaCC-CFTR signaling in the conjunctiva epithelium. Notably, the coupling effect of the ATP-induced CaCC-CFTR activation and intracellular Ca2+ may represent a promising therapeutic target for treating eDED.
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Affiliation(s)
- Jinyu Zhang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou 510060, China
| | - Limian Lin
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou 510060, China
| | - Xiaomin Chen
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou 510060, China
| | - Shuyi Wang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou 510060, China
| | - Yuan Wei
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou 510060, China
| | - Wenliang Zhou
- School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Shuangjian Yang
- Guangdong Institute for Vision and Eye Research, Guangzhou 510060, China
| | - Shiyou Zhou
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou 510060, China
- Correspondence:
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2
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Vallon V, Unwin R, Inscho EW, Leipziger J, Kishore BK. Extracellular Nucleotides and P2 Receptors in Renal Function. Physiol Rev 2019; 100:211-269. [PMID: 31437091 DOI: 10.1152/physrev.00038.2018] [Citation(s) in RCA: 58] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The understanding of the nucleotide/P2 receptor system in the regulation of renal hemodynamics and transport function has grown exponentially over the last 20 yr. This review attempts to integrate the available data while also identifying areas of missing information. First, the determinants of nucleotide concentrations in the interstitial and tubular fluids of the kidney are described, including mechanisms of cellular release of nucleotides and their extracellular breakdown. Then the renal cell membrane expression of P2X and P2Y receptors is discussed in the context of their effects on renal vascular and tubular functions. Attention is paid to effects on the cortical vasculature and intraglomerular structures, autoregulation of renal blood flow, tubuloglomerular feedback, and the control of medullary blood flow. The role of the nucleotide/P2 receptor system in the autocrine/paracrine regulation of sodium and fluid transport in the tubular and collecting duct system is outlined together with its role in integrative sodium and fluid homeostasis and blood pressure control. The final section summarizes the rapidly growing evidence indicating a prominent role of the extracellular nucleotide/P2 receptor system in the pathophysiology of the kidney and aims to identify potential therapeutic opportunities, including hypertension, lithium-induced nephropathy, polycystic kidney disease, and kidney inflammation. We are only beginning to unravel the distinct physiological and pathophysiological influences of the extracellular nucleotide/P2 receptor system and the associated therapeutic perspectives.
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Affiliation(s)
- Volker Vallon
- Departments of Medicine and Pharmacology, University of California San Diego & VA San Diego Healthcare System, San Diego, California; Centre for Nephrology, Division of Medicine, University College London, London, United Kingdom; IMED ECD CVRM R&D, AstraZeneca, Gothenburg, Sweden; Department of Medicine, Division of Nephrology, The University of Alabama at Birmingham, Birmingham, Alabama; Department of Biomedicine/Physiology, Aarhus University, Aarhus, Denmark; Departments of Internal Medicine and Nutrition and Integrative Physiology, and Center on Aging, University of Utah Health & Nephrology Research, VA Salt Lake City Healthcare System, Salt Lake City, Utah
| | - Robert Unwin
- Departments of Medicine and Pharmacology, University of California San Diego & VA San Diego Healthcare System, San Diego, California; Centre for Nephrology, Division of Medicine, University College London, London, United Kingdom; IMED ECD CVRM R&D, AstraZeneca, Gothenburg, Sweden; Department of Medicine, Division of Nephrology, The University of Alabama at Birmingham, Birmingham, Alabama; Department of Biomedicine/Physiology, Aarhus University, Aarhus, Denmark; Departments of Internal Medicine and Nutrition and Integrative Physiology, and Center on Aging, University of Utah Health & Nephrology Research, VA Salt Lake City Healthcare System, Salt Lake City, Utah
| | - Edward W Inscho
- Departments of Medicine and Pharmacology, University of California San Diego & VA San Diego Healthcare System, San Diego, California; Centre for Nephrology, Division of Medicine, University College London, London, United Kingdom; IMED ECD CVRM R&D, AstraZeneca, Gothenburg, Sweden; Department of Medicine, Division of Nephrology, The University of Alabama at Birmingham, Birmingham, Alabama; Department of Biomedicine/Physiology, Aarhus University, Aarhus, Denmark; Departments of Internal Medicine and Nutrition and Integrative Physiology, and Center on Aging, University of Utah Health & Nephrology Research, VA Salt Lake City Healthcare System, Salt Lake City, Utah
| | - Jens Leipziger
- Departments of Medicine and Pharmacology, University of California San Diego & VA San Diego Healthcare System, San Diego, California; Centre for Nephrology, Division of Medicine, University College London, London, United Kingdom; IMED ECD CVRM R&D, AstraZeneca, Gothenburg, Sweden; Department of Medicine, Division of Nephrology, The University of Alabama at Birmingham, Birmingham, Alabama; Department of Biomedicine/Physiology, Aarhus University, Aarhus, Denmark; Departments of Internal Medicine and Nutrition and Integrative Physiology, and Center on Aging, University of Utah Health & Nephrology Research, VA Salt Lake City Healthcare System, Salt Lake City, Utah
| | - Bellamkonda K Kishore
- Departments of Medicine and Pharmacology, University of California San Diego & VA San Diego Healthcare System, San Diego, California; Centre for Nephrology, Division of Medicine, University College London, London, United Kingdom; IMED ECD CVRM R&D, AstraZeneca, Gothenburg, Sweden; Department of Medicine, Division of Nephrology, The University of Alabama at Birmingham, Birmingham, Alabama; Department of Biomedicine/Physiology, Aarhus University, Aarhus, Denmark; Departments of Internal Medicine and Nutrition and Integrative Physiology, and Center on Aging, University of Utah Health & Nephrology Research, VA Salt Lake City Healthcare System, Salt Lake City, Utah
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3
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Wu Q, Moeller HB, Stevens DA, Sanchez-Hodge R, Childers G, Kortenoeven MLA, Cheng L, Rosenbaek LL, Rubel C, Patterson C, Pisitkun T, Schisler JC, Fenton RA. CHIP Regulates Aquaporin-2 Quality Control and Body Water Homeostasis. J Am Soc Nephrol 2017; 29:936-948. [PMID: 29242247 DOI: 10.1681/asn.2017050526] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Accepted: 11/14/2017] [Indexed: 02/03/2023] Open
Abstract
The importance of the kidney distal convoluted tubule (DCT) and cortical collecting duct (CCD) is highlighted by various water and electrolyte disorders that arise when the unique transport properties of these segments are disturbed. Despite this critical role, little is known about which proteins have a regulatory role in these cells and how these cells can be regulated by individual physiologic stimuli. By combining proteomics, bioinformatics, and cell biology approaches, we found that the E3 ubiquitin ligase CHIP is highly expressed throughout the collecting duct; is modulated in abundance by vasopressin; interacts with aquaporin-2 (AQP2), Hsp70, and Hsc70; and can directly ubiquitylate the water channel AQP2 in vitro shRNA knockdown of CHIP in CCD cells increased AQP2 protein t1/2 and reduced AQP2 ubiquitylation, resulting in greater levels of AQP2 and phosphorylated AQP2. CHIP knockdown increased the plasma membrane abundance of AQP2 in these cells. Compared with wild-type controls, CHIP knockout mice or novel CRISPR/Cas9 mice without CHIP E3 ligase activity had greater AQP2 abundance and altered renal water handling, with decreased water intake and urine volume, alongside higher urine osmolality. We did not observe significant changes in other water- or sodium-transporting proteins in the gene-modified mice. In summary, these results suggest that CHIP regulates AQP2 and subsequently, renal water handling.
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Affiliation(s)
- Qi Wu
- InterPrET Center, Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Hanne B Moeller
- InterPrET Center, Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | | | - Rebekah Sanchez-Hodge
- McAllister Heart Institute and.,Department of Pharmacology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Gabrielle Childers
- McAllister Heart Institute and.,Department of Pharmacology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | | | - Lei Cheng
- InterPrET Center, Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Lena L Rosenbaek
- InterPrET Center, Department of Biomedicine, Aarhus University, Aarhus, Denmark.,Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | | | - Cam Patterson
- Presbyterian Hospital/Weill-Cornell Medical Center, New York, New York; and
| | - Trairak Pisitkun
- InterPrET Center, Department of Biomedicine, Aarhus University, Aarhus, Denmark.,Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
| | - Jonathan C Schisler
- McAllister Heart Institute and.,Department of Pharmacology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Robert A Fenton
- InterPrET Center, Department of Biomedicine, Aarhus University, Aarhus, Denmark;
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Ilatovskaya DV, Palygin O, Staruschenko A. Functional and therapeutic importance of purinergic signaling in polycystic kidney disease. Am J Physiol Renal Physiol 2016; 311:F1135-F1139. [PMID: 27654892 DOI: 10.1152/ajprenal.00406.2016] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Accepted: 09/20/2016] [Indexed: 12/12/2022] Open
Abstract
Polycystic kidney diseases (PKD) are a group of inherited nephropathies marked with the formation of fluid-filled cysts along the nephron. This renal disorder affects millions of people worldwide, but current treatment strategies are unfortunately limited to supportive therapy, dietary restrictions, and, eventually, renal transplantation. Recent advances in PKD management are aimed at targeting exaggerated cell proliferation and dedifferentiation to interfere with cyst growth. However, not nearly enough is known about the ion transport properties of the cystic cells, or specific signaling pathways modulating channels and transporters in this condition. There is growing evidence that abnormally elevated concentrations of adenosine triphosphate (ATP) in PKD may contribute to cyst enlargement; change in the profile of purinergic receptors may also result in promotion of cystogenesis. The current mini-review is focused on the role of ATP and associated signaling affecting ion transport properties of the renal cystic epithelia.
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Affiliation(s)
- Daria V Ilatovskaya
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Oleg Palygin
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
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Abstract
PURPOSE OF REVIEW Renal collecting ducts maintain NaCl homeostasis by fine-tuning urinary excretion to balance dietary salt intake. This review focuses on recent studies on transcellular Cl secretion by collecting ducts, its regulation and its role in cyst growth in autosomal dominant polycystic kidney disease (ADPKD). RECENT FINDINGS Lumens of nonperfused rat medullary collecting ducts collapse in control media but expand with fluid following treatment with cAMP, demonstrating the capacity for both salt absorption and secretion. Recently, inhibition of apical epithelial Na channels (ENaC) unmasked Cl secretion in perfused mouse cortical collecting ducts (CCDs), involving Cl uptake by basolateral NKCC1 and efflux through apical Cl channels. AVP, the key hormone for osmoregulation, promotes cystic fibrosis transmembrane conductance regulator (CFTR)-mediated Cl secretion. In addition, prostaglandin E2 stimulates Cl secretion through both CFTR and Ca-activated Cl channels. SUMMARY Renal Cl secretion has been commonly overlooked because of the overwhelming capacity for the nephron to reabsorb NaCl from the glomerular filtrate. In ADPKD, Cl secretion plays a central role in the accumulation of cyst fluid and the remarkable size of the cystic kidneys. Investigation of renal Cl secretion may provide a better understanding of NaCl homeostasis and identify new approaches to reduce cyst growth in PKD.
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6
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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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7
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Zhang Y, Robson SC, Morris KL, Heiney KM, Dwyer KM, Kishore BK, Ecelbarger CM. Impaired natriuretic response to high-NaCl diet plus aldosterone infusion in mice overexpressing human CD39, an ectonucleotidase (NTPDase1). Am J Physiol Renal Physiol 2015; 308:F1398-408. [PMID: 25877509 DOI: 10.1152/ajprenal.00125.2014] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2014] [Accepted: 04/09/2015] [Indexed: 01/14/2023] Open
Abstract
Extracellular nucleotides acting through P2 receptors facilitate natriuresis. To define how purinergic mechanisms are involved in sodium homeostasis, we used transgenic (TG) mice that globally overexpress human CD39 (hCD39, NTPDase1), an ectonucleotidase that hydrolyzes extracellular ATP/ADP to AMP, resulting in an altered extracellular purine profile. On a high-sodium diet (HSD, 3.5% Na(+)), urine volume and serum sodium were significantly higher in TG mice but sodium excretion was unaltered. Furthermore, TG mice showed an attenuated fall in urine aldosterone with HSD. Western blot analysis revealed significantly lower densities (∼40%) of the β-subunit of the epithelial sodium channel (ENaC) in medulla, and the major band (85-kDa) of γ-ENaC in TG mice cortex. To evaluate aldosterone-independent differences, in a second experiment, aldosterone was clamped by osmotic minipump at 20 μg/day, and mice were fed either an HSD or a low-sodium diet (LSD, 0.03% Na(+)). Here, no differences in urine volume or osmolality, or serum aldosterone were found, but TG mice showed a modest, yet significant impairment in late natriuresis (days 3 and 4). Several major sodium transporters or channel subunits were differentially expressed between the genotypes. HSD caused a downregulation of Na-Cl cotransporter (NCC) in both genotypes; and had higher cortical levels of NCC, Na-K-ATPase (α-1 subunit), and α- and γ-ENaC. The Na-K-2Cl cotransporter (NKCC2) was downregulated by HSD in wild-type mice, but it increased in TG mice. In summary, our data support the concept that extracellular nucleotides facilitate natriuresis; they also reveal an aldosterone-independent downregulation of major renal sodium transporters and channel subunits by purinergic signaling.
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Affiliation(s)
- Yue Zhang
- Nephrology Research, Department of Veterans Administration Salt Lake City Health Care System, Salt Lake City, Utah; Department of Medicine, University of Utah Health Sciences Center, Salt Lake City, Utah
| | - Simon C Robson
- Transplant Institute and Gastroenterology Division, Beth Israel Deaconess Medical Center, Boston, Massachusetts; Harvard Medical School, Harvard University, Boston, Massachusetts
| | - Kaiya L Morris
- Nephrology Research, Department of Veterans Administration Salt Lake City Health Care System, Salt Lake City, Utah; Department of Medicine, University of Utah Health Sciences Center, Salt Lake City, Utah
| | - Kristina M Heiney
- Nephrology Research, Department of Veterans Administration Salt Lake City Health Care System, Salt Lake City, Utah; Department of Medicine, University of Utah Health Sciences Center, Salt Lake City, Utah
| | - Karen M Dwyer
- Immunology Research Center, Department of Medicine, University of Melbourne, St. Vincent's Hospital, Fitzroy, Australia
| | - Bellamkonda K Kishore
- Nephrology Research, Department of Veterans Administration Salt Lake City Health Care System, Salt Lake City, Utah; Department of Medicine, University of Utah Health Sciences Center, Salt Lake City, Utah; Center on Aging, University of Utah Health Sciences Center, Salt Lake City, Utah;
| | - Carolyn M Ecelbarger
- Department of Medicine, Georgetown University, Washington, DC; and Center for the Study of Sex Differences in Health, Aging, and Disease, Georgetown University, Washington, District of Columbia
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Solini A, Usuelli V, Fiorina P. The dark side of extracellular ATP in kidney diseases. J Am Soc Nephrol 2014; 26:1007-16. [PMID: 25452669 DOI: 10.1681/asn.2014070721] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Intracellular ATP is the most vital source of cellular energy for biologic systems, whereas extracellular ATP is a multifaceted mediator of several cell functions via its interaction, in an autocrine or paracrine manner, with P2 purinergic receptors expressed on the cell surface. These ionotropic and metabotropic P2 purinergic receptors modulate a variety of physiologic events upon the maintenance of a highly sensitive "set point," the derangement of which may lead to the development of key pathogenic mechanisms during acute and chronic diseases. Growing evidence suggests that extracellular ATP signaling via P2 purinergic receptors may be involved in different renal pathologic conditions. For these reasons, investigators and pharmaceutical companies are actively exploring novel strategies to antagonize or block these receptors with the goal of reducing extracellular ATP production or accelerating extracellular ATP clearance. Targeting extracellular ATP signaling, particularly through the P2X7 receptor, has considerable translational potential, given that novel P2X7-receptor inhibitors are already available for clinical use (e.g., CE224,535, AZD9056, and GSK1482160). This review summarizes the current evidence regarding the involvement of extracellular ATP and its P2 purinergic receptor-mediated signaling in physiologic and pathologic processes in the kidney; potential therapeutic options targeting extracellular ATP purinergic receptors are analyzed as well.
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Affiliation(s)
- Anna Solini
- Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Vera Usuelli
- Division of Transplant Medicine, San Raffaele Hospital, Milan, Italy; and
| | - Paolo Fiorina
- Division of Transplant Medicine, San Raffaele Hospital, Milan, Italy; and Nephrology Division, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
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9
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Svenningsen P, Nielsen MR, Marcussen N, Walter S, Jensen BL. TMEM16A is a Ca(2+) -activated Cl(-) channel expressed in the renal collecting duct. Acta Physiol (Oxf) 2014; 212:166-74. [PMID: 24913262 DOI: 10.1111/apha.12323] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Revised: 05/16/2014] [Accepted: 06/03/2014] [Indexed: 01/10/2023]
Abstract
AIM In the renal collecting ducts, ATP stimulates a Ca(2+) -activated chloride current. The identity of the channel responsible for the current under physiological conditions is not known and it was hypothesized that TMEM16a is a relevant candidate in the renal collecting duct. METHODS The cortical collecting duct cell line M-1 was used as a model of the collecting duct. The ATP induced Ca(2+) signalling was imaged in cells loaded with Ca(2+) -sensitive fluorescent probes using confocal laser-scanning fluorescence microscopy. Chloride current was determined by mounting M-1 cell layers in Ussing chamber. The expression of TMEM16a in human kidney was tested by immunohistochemistry. RESULTS M-1 cells displayed a transient increase in intracellular Ca(2+) concentration in response to 100 nm ATP. This response was completely blocked by addition of 100 μm suramin, indicating that ATP signals through purinergic P2 receptors. Apical addition of 100 nm ATP induced a Cl(-) current, which was blocked by suramin, DPC and the cysteine-modifying compound MTSET. M-1 cells were found to express TMEM16a at the mRNA and protein level. Functionally, it was found that knock-down of TMEM16a expression in M-1 cells inhibited the ATP induced Cl(-) -current. In human and mouse kidney sections, TMEM16a protein expression was localized to the collecting duct, and TMEM16a was found to be excreted in human urinary exosomes. CONCLUSION TMEM16a is a Ca(2+) -activated Cl(-) channel expressed in the collecting ducts.
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Affiliation(s)
- P. Svenningsen
- Department of Cardiovascular and Renal Research; Institute of Molecular Medicine; University of Southern Denmark; Odense Denmark
| | - M. R. Nielsen
- Department of Cardiovascular and Renal Research; Institute of Molecular Medicine; University of Southern Denmark; Odense Denmark
| | - N. Marcussen
- Department of Clinical Pathology; Odense University Hospital; Odense Denmark
| | - S. Walter
- Department of Urology; Odense University Hospital; Odense Denmark
| | - B. L. Jensen
- Department of Cardiovascular and Renal Research; Institute of Molecular Medicine; University of Southern Denmark; Odense Denmark
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Yusef YR, Thomas W, Harvey BJ. Estrogen increases ENaC activity via PKCδ signaling in renal cortical collecting duct cells. Physiol Rep 2014; 2:2/5/e12020. [PMID: 24872356 PMCID: PMC4098747 DOI: 10.14814/phy2.12020] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
The most active estrogen, 17β‐estradiol (E2), has previously been shown to stimulate a female sex‐specific antisecretory response in the intestine. This effect is thought to contribute to the increase in whole body extracellular fluid (ECF) volume which occurs in high estrogen states, such as in the implantation window during estrous cycle. The increased ECF volume may be short‐circuited by a renal compensation unless estrogen exerts a proabsorptive effect in the nephron. Thus, the effect of E2 on ENaC in kidney cortical collecting duct (CCD) cells is of interest to understand estrogen regulation of ECF volume. Previous studies showed a rapid stimulatory effect of estrogen on ENaC in bronchial epithelium. In this study we examined if such a rapid effect on Na+ absorption could occur in the kidney. Experiments were carried out on murine M1‐CCD cell cultures. E2 (25 nmol/L) treatment caused a rapid‐onset (<15 min) and sustained increase in the amiloride‐sensitive Na+ current (INa) in CCD monolayers mounted in Ussing chambers (control, 1.9 ± 0.2 μA/cm2; E2, 4.7 ± 0.3 μA/cm2; n = 43, P < 0.001), without affecting the ouabain‐sensitive Na+/K+ pump current. The INa response to E2 was inhibited by PKCδ activity antagonism with rottlerin (5 μmol/L), inhibition of matrix metalloproteinases activity with GM6001 (1 μmol/L), inhibition of EGFR activity with AG1478 (10 μmol/L), inhibition of PLC activity with U‐73122 (10 μmol/L), and inhibition of estrogen receptors with the general ER antagonist ICI‐182780 (100 nmol/L). The estrogen activation of INa could be mimicked by the ERα agonist PPT (1 nmol/L). The nuclear excluded estrogen dendrimer conjugate (EDC) induced similar stimulatory effects on INa comparable to free E2. The end target for E2 stimulation of PKCδ was shown to be an increased abundance of the γ‐ENaC subunit in the apical plasma membrane of CCD cells. We have demonstrated a novel rapid “nongenomic” function of estrogen to stimulate ENaC via ERα‐EGFR transactivation in kidney CCD cells. We propose that the salt‐retaining effect of estrogen in the kidney together with its antisecretory action in the intestine are the molecular mechanisms causing the expanded ECF volume in high‐estrogen states. Estrogen stimulates sodium absorption in kidney cells. This rapid “nongenomic” response to estrogen is transduced via estrogen receptor transactivation of the epidermal growth factor receptor. The ER‐EGFR transactivation triggers a protein kinase signaling cascade which culminates in the insertion of sodium channel subunits into the cell membrane. Estrogen is a novel salt‐retaining hormone with proabsorptive effects in kidney and antisecretory actions in intestine.
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Affiliation(s)
- Yamil R Yusef
- Department of Molecular Medicine, Royal College of Surgeons in Ireland, RCSI Education and Research Centre, Beaumont Hospital, Dublin, Ireland
| | - Warren Thomas
- Department of Molecular Medicine, Royal College of Surgeons in Ireland, RCSI Education and Research Centre, Beaumont Hospital, Dublin, Ireland
| | - Brian J Harvey
- Department of Molecular Medicine, Royal College of Surgeons in Ireland, RCSI Education and Research Centre, Beaumont Hospital, Dublin, Ireland
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11
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Ruppersburg CC, Hartzell HC. The Ca2+-activated Cl- channel ANO1/TMEM16A regulates primary ciliogenesis. Mol Biol Cell 2014; 25:1793-807. [PMID: 24694595 PMCID: PMC4038505 DOI: 10.1091/mbc.e13-10-0599] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The Ca2+-activated Cl− channel ANO1/TMEM16A is located in the primary cilium, and blocking it pharmacologically or knocking it down with shRNA interferes with ciliogenesis. Before ciliogenesis, the channel is organized into a torus-shaped structure (the “nimbus”) enriched in proteins required for ciliogenesis. Many cells possess a single, nonmotile, primary cilium highly enriched in receptors and sensory transduction machinery that plays crucial roles in cellular morphogenesis. Although sensory transduction requires ion channels, relatively little is known about ion channels in the primary cilium (with the exception of TRPP2). Here we show that the Ca2+-activated Cl− channel anoctamin-1 (ANO1/TMEM16A) is located in the primary cilium and that blocking its channel function pharmacologically or knocking it down with short hairpin RNA interferes with ciliogenesis. Before ciliogenesis, the channel becomes organized into a torus-shaped structure (“the nimbus”) enriched in proteins required for ciliogenesis, including the small GTPases Cdc42 and Arl13b and the exocyst complex component Sec6. The nimbus excludes F-actin and coincides with a ring of acetylated microtubules. The nimbus appears to form before, or independent of, apical docking of the mother centriole. Our data support a model in which the nimbus provides a scaffold for staging of ciliary components for assembly very early in ciliogenesis and chloride transport by ANO1/TMEM16A is required for the genesis or maintenance of primary cilia.
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Affiliation(s)
| | - H Criss Hartzell
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322
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Burnstock G, Evans LC, Bailey MA. Purinergic signalling in the kidney in health and disease. Purinergic Signal 2014; 10:71-101. [PMID: 24265071 PMCID: PMC3944043 DOI: 10.1007/s11302-013-9400-5] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2013] [Accepted: 10/24/2013] [Indexed: 12/21/2022] Open
Abstract
The involvement of purinergic signalling in kidney physiology and pathophysiology is rapidly gaining recognition and this is a comprehensive review of early and recent publications in the field. Purinergic signalling involvement is described in several important intrarenal regulatory mechanisms, including tuboglomerular feedback, the autoregulatory response of the glomerular and extraglomerular microcirculation and the control of renin release. Furthermore, purinergic signalling influences water and electrolyte transport in all segments of the renal tubule. Reports about purine- and pyrimidine-mediated actions in diseases of the kidney, including polycystic kidney disease, nephritis, diabetes, hypertension and nephrotoxicant injury are covered and possible purinergic therapeutic strategies discussed.
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Affiliation(s)
- Geoffrey Burnstock
- Autonomic Neuroscience Centre, University College Medical School, Rowland Hill Street, London, NW3 2PF, UK,
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Rajagopal M, Thomas SV, Kathpalia PP, Chen Y, Pao AC. Prostaglandin E2 induces chloride secretion through crosstalk between cAMP and calcium signaling in mouse inner medullary collecting duct cells. Am J Physiol Cell Physiol 2013; 306:C263-78. [PMID: 24284792 DOI: 10.1152/ajpcell.00381.2012] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Under conditions of high dietary salt intake, prostaglandin E2 (PGE2) production is increased in the collecting duct and promotes urinary sodium chloride (NaCl) excretion; however, the molecular mechanisms by which PGE2 increases NaCl excretion in this context have not been clearly defined. We used the mouse inner medullary collecting duct (mIMCD)-K2 cell line to characterize mechanisms underlying PGE2-regulated NaCl transport. When epithelial Na(+) channels were inhibited, PGE2 exclusively stimulated basolateral EP4 receptors to increase short-circuit current (Isc(PGE2)). We found that Isc(PGE2) was sensitive to inhibition by H-89 and CFTR-172, indicating that EP4 receptors signal through protein kinase A to induce Cl(-) secretion via cystic fibrosis transmembrane conductance regulator (CFTR). Unexpectedly, we also found that Isc(PGE2) was sensitive to inhibition by BAPTA-AM (Ca(2+) chelator), 2-aminoethoxydiphenyl borate (2-APB) (inositol triphosphate receptor blocker), and flufenamic acid (FFA) [Ca(2+)-activated Cl(-) channel (CACC) inhibitor], suggesting that EP4 receptors also signal through Ca(2+) to induce Cl(-) secretion via CACC. Additionally, we observed that PGE2 stimulated an increase in Isc through crosstalk between cAMP and Ca(2+) signaling; BAPTA-AM or 2-APB inhibited a component of Isc(PGE2) that was sensitive to CFTR-172 inhibition; H-89 inhibited a component of Isc(PGE2) that was sensitive to FFA inhibition. Together, our findings indicate that PGE2 activates basolateral EP4 receptors and signals through both cAMP and Ca(2+) to stimulate Cl(-) secretion in IMCD-K2 cells. We propose that these signaling pathways, and the crosstalk between them, may provide a concerted mechanism for enhancing urinary NaCl excretion under conditions of high dietary NaCl intake.
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Affiliation(s)
- Madhumitha Rajagopal
- Division of Nephrology, Department of Medicine, Stanford University, Palo Alto, California; and
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