1
|
Banerjee S, Smith IM, Hengen AC, Stroka KM. Methods for studying mammalian aquaporin biology. Biol Methods Protoc 2023; 8:bpad031. [PMID: 38046463 PMCID: PMC10689382 DOI: 10.1093/biomethods/bpad031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Revised: 10/29/2023] [Accepted: 11/09/2023] [Indexed: 12/05/2023] Open
Abstract
Aquaporins (AQPs), transmembrane water-conducting channels, have earned a great deal of scrutiny for their critical physiological roles in healthy and disease cell states, especially in the biomedical field. Numerous methods have been implemented to elucidate the involvement of AQP-mediated water transport and downstream signaling activation in eliciting whole cell, tissue, and organ functional responses. To modulate these responses, other methods have been employed to investigate AQP druggability. This review discusses standard in vitro, in vivo, and in silico methods for studying AQPs, especially for biomedical and mammalian cell biology applications. We also propose some new techniques and approaches for future AQP research to address current gaps in methodology.
Collapse
Affiliation(s)
- Shohini Banerjee
- Fischell Department of Bioengineering, University of Maryland, MD 20742, United States
| | - Ian M Smith
- Fischell Department of Bioengineering, University of Maryland, MD 20742, United States
| | - Autumn C Hengen
- Fischell Department of Bioengineering, University of Maryland, MD 20742, United States
| | - Kimberly M Stroka
- Fischell Department of Bioengineering, University of Maryland, MD 20742, United States
- Marlene and Stewart Greenebaum Comprehensive Cancer Center, University of Maryland, Baltimore MD 21201, United States
- Biophysics Program, University of Maryland, MD 20742, United States
- Center for Stem Cell Biology and Regenerative Medicine, University of Maryland, Baltimore MD 21201, United States
| |
Collapse
|
2
|
McLaughlin AJ, Kaniski AI, Matti DI, Monear NC, Tischler JL, Xhabija B. Fluorene-9-bisphenol affects the terminal differentiation of mouse embryonic bodies. Curr Res Toxicol 2023; 5:100133. [PMID: 37964943 PMCID: PMC10641737 DOI: 10.1016/j.crtox.2023.100133] [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: 06/12/2023] [Revised: 10/28/2023] [Accepted: 10/30/2023] [Indexed: 11/16/2023] Open
Abstract
Fluorene-9-bisphenol (BHPF) has recently attracted interest as it is increasingly used in industrial settings as a substitute for Bisphenol A (BPA). However, the effects of BHPF exposure on embryonic stem cell (ESC) self-renewal, pluripotency, and differentiation remain poorly understood. This study investigates the impacts of BHPF on mouse embryonic stem cells (mESCs) and embryonic bodies (EBs). Our results reveal that BHPF exposure leads to a morphological shift in mESCs, reducing the percentage of dome-shaped colonies and indicating loss of self-renewal and pluripotency. BHPF exposure also appeared to affect the early stages of EB formation and their growth dynamics, with a reduction in EB numbers and an increase in their size. Subsequent gene expression analysis revealed that BHPF exposure led to increased expression of the inflammatory gene Il6, indicating a potential stress response. Furthermore, BHPF affected the terminal differentiation pathway, modulating the expression of 16 genes associated with distinct cell types, including lymphatic endothelium, keratinocyte epithelium, pancreatic beta cells, macrophages, monocytes, T-cells, neurons, retinal ganglion cells, nephrons proximal tubule cells, and cardiomyocytes. These findings offer insights into the impact of BHPF on ESC biology and suggest potential implications for developmental and neurodegenerative disorders. Future work should focus on elucidating the underlying mechanisms of BHPF-mediated effects on stem cell function. This may offer new perspectives for understanding the health impacts of environmental exposure to BHPF.
Collapse
Affiliation(s)
- Aidan J. McLaughlin
- College of Arts Sciences and Letters, Department of Natural Science, University of Michigan-Dearborn, Dearborn, MI 48128, United States
| | - Anthony I. Kaniski
- College of Arts Sciences and Letters, Department of Natural Science, University of Michigan-Dearborn, Dearborn, MI 48128, United States
| | - Darena I. Matti
- College of Arts Sciences and Letters, Department of Natural Science, University of Michigan-Dearborn, Dearborn, MI 48128, United States
| | - Nicodemus C. Monear
- College of Arts Sciences, Department of Natural Science, University of Michigan-Flint, Flint, MI, United States
| | - Jessica L. Tischler
- College of Arts Sciences, Department of Natural Science, University of Michigan-Flint, Flint, MI, United States
| | - Besa Xhabija
- College of Arts Sciences and Letters, Department of Natural Science, University of Michigan-Dearborn, Dearborn, MI 48128, United States
| |
Collapse
|
3
|
Hakimi S, Dutta P, Layton AT. Coupling of renal sodium and calcium transport: a modeling analysis of transporter inhibition and sex differences. Am J Physiol Renal Physiol 2023; 325:F536-F551. [PMID: 37615047 DOI: 10.1152/ajprenal.00145.2023] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Revised: 08/17/2023] [Accepted: 08/17/2023] [Indexed: 08/25/2023] Open
Abstract
Ca2+ transport along the nephron occurs via specific transcellular and paracellular pathways and is coupled to the transport of other electrolytes. Notably, Na+ transport establishes an electrochemical gradient to drive Ca2+ reabsorption. Hence, alterations in renal Na+ handling, under pathophysiological conditions or pharmacological manipulations, can have major effects on Ca2+ transport. An important class of pharmacological agent is diuretics, which are commonly prescribed for the management of blood pressure and fluid balance. The pharmacological targets of diuretics generally directly facilitate Na+ transport but also indirectly affect renal Ca2+ handling. To better understand the underlying mechanisms, we developed a computational model of electrolyte transport along the superficial nephron in the kidney of a male and female rat. Sex differences in renal Ca2+ handling are represented. Model simulations predicted in the female rat nephron lower Ca2+ reabsorption in the proximal tubule and thick ascending limb, but higher reabsorption in the late distal convoluted tubule and connecting tubule, compared with the male nephron. The male rat kidney model yielded a higher urinary Ca2+ excretion than the female model, consistent with animal experiments. Model results indicated that along the proximal tubule and thick ascending limb, Ca2+ and Na+ transport occurred in parallel, but those processes were dissociated in the distal convoluted tubule. Additionally, we conducted simulations of inhibition of channels and transporters that play a major role in Na+ and Ca2+ transport. Simulation results revealed alterations in transepithelial Ca2+ transport, with differential effects among nephron segments and between the sexes.NEW & NOTEWORTHY The kidney plays an important role in the maintenance of whole body Ca2+ balance by regulating Ca2+ reabsorption and excretion. This computational modeling study provides insights into how Ca2+ transport along the nephron is coupled to Na+. Model results indicated that along the proximal tubule and thick ascending limb, Ca2+ and Na+ transport occur in parallel, but those processes were dissociated in the distal convoluted tubule. Simulations also revealed sex-specific responses to different pharmacological manipulations.
Collapse
Affiliation(s)
- Shervin Hakimi
- Department of Applied Mathematics, University of Waterloo, Waterloo, Ontario, Canada
| | - Pritha Dutta
- Department of Applied Mathematics, University of Waterloo, Waterloo, Ontario, Canada
| | - Anita T Layton
- Department of Applied Mathematics, University of Waterloo, Waterloo, Ontario, Canada
- Department of Biology, Cheriton School of Computer Science, and School of Pharmacology, University of Waterloo, Waterloo, Ontario, Canada
| |
Collapse
|
4
|
Pajenda S, Hevesi Z, Eder M, Gerges D, Aiad M, Koldyka O, Winnicki W, Wagner L, Eskandary F, Schmidt A. Lessons from Polyomavirus Immunofluorescence Staining of Urinary Decoy Cells. Life (Basel) 2023; 13:1526. [PMID: 37511901 PMCID: PMC10381542 DOI: 10.3390/life13071526] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Revised: 06/28/2023] [Accepted: 07/06/2023] [Indexed: 07/30/2023] Open
Abstract
Decoy cells that can be detected in the urine sediment of immunosuppressed patients are often caused by the uncontrolled replication of polyomaviruses, such as BK-Virus (BKV) and John Cunningham (JC)-Virus (JCV), within the upper urinary tract. Due to the wide availability of highly sensitive BKV and JCV PCR, the diagnostic utility of screening for decoy cells in urine as an indicator of polyomavirus-associated nephropathy (PyVAN) has been questioned by some institutions. We hypothesize that specific staining of different infection time-dependent BKV-specific antigens in urine sediment could allow cell-specific mapping of antigen expression during decoy cell development. Urine sediment cells from six kidney transplant recipients (five males, one female) were stained for the presence of the early BKV gene transcript lTag and the major viral capsid protein VP1 using monospecific antibodies, monoclonal antibodies and confocal microscopy. For this purpose, cyto-preparations were prepared and the BK polyoma genotype was determined by sequencing the PCR-amplified coding region of the VP1 protein. lTag staining began at specific sites in the nucleus and spread across the nucleus in a cobweb-like pattern as the size of the nucleus increased. It spread into the cytosol as soon as the nuclear membrane was fragmented or dissolved, as in apoptosis or in the metaphase of the cell cycle. In comparison, we observed that VP1 staining started in the nuclear region and accumulated at the nuclear edge in 6-32% of VP1+ cells. The staining traveled through the cytosol of the proximal tubule cell and reached high intensities at the cytosol before spreading to the surrounding area in the form of exosome-like particles. The spreading virus-containing particles adhered to surrounding cells, including erythrocytes. VP1-positive proximal tubule cells contain apoptotic bodies, with 68-94% of them losing parts of their DNA and exhibiting membrane damage, appearing as "ghost cells" but still VP1+. Specific polyoma staining of urine sediment cells can help determine and enumerate exfoliation of BKV-positive cells based on VP1 staining, which exceeds single-face decoy staining in terms of accuracy. Furthermore, our staining approaches might serve as an early readout in primary diagnostics and for the evaluation of treatment responses in the setting of reduced immunosuppression.
Collapse
Affiliation(s)
- Sahra Pajenda
- Division of Nephrology and Dialysis, Department of Internal Medicine III, Medical University of Vienna, 1090 Vienna, Austria
| | - Zsofia Hevesi
- Center for Brain Research, Medical University of Vienna, 1090 Vienna, Austria
| | - Michael Eder
- Division of Nephrology and Dialysis, Department of Internal Medicine III, Medical University of Vienna, 1090 Vienna, Austria
| | - Daniela Gerges
- Division of Nephrology and Dialysis, Department of Internal Medicine III, Medical University of Vienna, 1090 Vienna, Austria
| | - Monika Aiad
- Division of Nephrology and Dialysis, Department of Internal Medicine III, Medical University of Vienna, 1090 Vienna, Austria
| | - Oliver Koldyka
- Division of Endocrinology and Metabolism, Department of Internal Medicine III, Medical University of Vienna, 1090 Vienna, Austria
| | - Wolfgang Winnicki
- Division of Nephrology and Dialysis, Department of Internal Medicine III, Medical University of Vienna, 1090 Vienna, Austria
| | - Ludwig Wagner
- Division of Nephrology and Dialysis, Department of Internal Medicine III, Medical University of Vienna, 1090 Vienna, Austria
| | - Farsad Eskandary
- Division of Nephrology and Dialysis, Department of Internal Medicine III, Medical University of Vienna, 1090 Vienna, Austria
| | - Alice Schmidt
- Division of Nephrology and Dialysis, Department of Internal Medicine III, Medical University of Vienna, 1090 Vienna, Austria
| |
Collapse
|
5
|
Alexander RT. Kidney stones, hypercalciuria, and recent insights into proximal tubule calcium reabsorption. Curr Opin Nephrol Hypertens 2023; 32:359-365. [PMID: 37074688 DOI: 10.1097/mnh.0000000000000892] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/20/2023]
Abstract
PURPOSE OF REVIEW Most kidney stones are composed of calcium, and the greatest risk factor for kidney stone formation is hypercalciuria. Patients who form kidney stones often have reduced calcium reabsorption from the proximal tubule, and increasing this reabsorption is a goal of some dietary and pharmacological treatment strategies to prevent kidney stone recurrence. However, until recently, little was known about the molecular mechanism that mediates calcium reabsorption from the proximal tubule. This review summarizes newly uncovered key insights and discusses how they may inform the treatment of kidney stone formers. RECENT FINDINGS Studies examining claudin-2 and claudin-12 single and double knockout mice, combined with cell culture models, support complementary independent roles for these tight junction proteins in contributing paracellular calcium permeability to the proximal tubule. Moreover, a family with a coding variation in claudin-2 causing hypercalciuria and kidney stones have been reported, and reanalysis of Genome Wide Association Study (GWAS) data demonstrates an association between noncoding variations in CLDN2 and kidney stone formation. SUMMARY The current work begins to delineate the molecular mechanisms whereby calcium is reabsorbed from the proximal tubule and suggests a role for altered claudin-2 mediated calcium reabsorption in the pathogenesis of hypercalciuria and kidney stone formation.
Collapse
Affiliation(s)
- R Todd Alexander
- Department of Pediatrics
- Department of Physiology, University of Alberta
- The Women's & Children's Health Research Institute, Edmonton, Alberta, Canada
| |
Collapse
|
6
|
Qiu Z, Jiang T, Li Y, Wang W, Yang B. Aquaporins in Urinary System. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2023; 1398:155-177. [PMID: 36717493 DOI: 10.1007/978-981-19-7415-1_11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
There are at least eight aquaporins (AQPs) expressed in the kidney. Including AQP1 expressed in proximal tubules, thin descending limb of Henle and vasa recta; AQP2, AQP3, AQP4, AQP5, and AQP6 expressed in collecting ducts; AQP7 expressed in proximal tubules; AQP8 expressed in proximal tubules and collecting ducts; and AQP11 expressed in the endoplasmic reticulum of proximal tubular epithelial cells. Over years, researchers have constructed different AQP knockout mice and explored the effect of AQP knockout on kidney function. Thus, the roles of AQPs in renal physiology are revealed, providing very useful information for addressing fundamental questions about transepithelial water transport and the mechanism of near isoosmolar fluid reabsorption. This chapter introduces the localization and function of AQPs in the kidney and their roles in different kidney diseases to reveal the prospects of AQPs in further basic and clinical studies.
Collapse
Affiliation(s)
- Zhiwei Qiu
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Pharmacology, School of Basic Medical Sciences, Peking University, Beijing, China
| | - Tao Jiang
- College of Basic Medicine, Beihua University, Jilin, China
| | - Yingjie Li
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Pharmacology, School of Basic Medical Sciences, Peking University, Beijing, China
| | - Weiling Wang
- Beijing Research Institute of Chinese Medicine, Beijing University of Chinese Medicine, Beijing, P.R. China
| | - Baoxue Yang
- School of Basic Medical Sciences, Peking University, Beijing, China.
| |
Collapse
|
7
|
Du Z, Yan Q, Shen E, Weinstein AM, Wang T. Regulation of glomerulotubular balance. IV. Implication of aquaporin 1 in flow-dependent proximal tubule transport and cell volume. Am J Physiol Renal Physiol 2022; 323:F642-F653. [PMID: 36108052 PMCID: PMC9705020 DOI: 10.1152/ajprenal.00167.2022] [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: 06/14/2022] [Revised: 09/06/2022] [Accepted: 09/14/2022] [Indexed: 12/14/2022] Open
Abstract
The water channel aquaporin-1 (AQP1) is the principal water pathway for isotonic water reabsorption in the kidney proximal tubule (PT). We investigated flow-mediated fluid (Jv) and [Formula: see text] ([Formula: see text]) reabsorption in PTs of the mouse kidney by microperfusion in wild-type (WT) and AQP1 knockout (KO) mice. Experiments were simulated in an adaptation of a mathematical model of the rat PT. An increase in perfusion rate from 5 to 20 nL/min increased Jv and [Formula: see text] in PTs of WT mice. AQP1 KO mice significantly decreased Jv at low and high flow rates compared with control. In contrast, [Formula: see text] was not reduced at either low or high flow rates. Cell volume showed no significant difference between WT and AQP1 KO mice. Renal clearance experiments showed significantly higher urine flow in AQP1 KO mice, but there was no significant difference in either Na+ and K+ or [Formula: see text] excretion. Acid-base parameters of blood pH, Pco2, [Formula: see text], and urine pH were the same in both WT and KO mice. In model calculations, tubules whose tight junction (TJ) water permeability (Pf) was that assigned to the rat TJ, showed no difference in Jv between WT and KO, whereas TJ Pf set to 25% of the rat predicted Jv concordant with our observations from AQP1 KO. These results affirm the dominance of AQP1 in mediating isotonic water reabsorption by the mouse PT and demonstrate that flow-stimulated [Formula: see text] reabsorption is intact and independent of AQP1. With reference to the model, the findings also suggest that TJ water flux in the PT is less prominent in the mouse than in the rat kidney.NEW & NOTEWORTHY We found an absence of flow-dependent modulation of fluid absorption but no effect on either proximal tubule (PT) [Formula: see text] absorption or acid-base parameters in the aquaporin 1 (AQP1) knockout mouse. We affirmed the dominance of the water channel AQP1 in mediating isotonic water reabsorption by the mouse PT and demonstrated that flow-stimulated [Formula: see text] reabsorption is independent of AQP1. With reference to the model, the findings also suggest that tight junctional water flux in the PT is less prominent in the mouse than rat kidney.
Collapse
Affiliation(s)
- Zhaopeng Du
- Department of Cellular and Molecular Physiology, Yale University, New Haven, Connecticut
| | - Qingshang Yan
- Department of Cellular and Molecular Physiology, Yale University, New Haven, Connecticut
| | - Emma Shen
- Department of Cellular and Molecular Physiology, Yale University, New Haven, Connecticut
| | - Alan M Weinstein
- Department of Physiology and Biophysics, Weill Medical College, Cornell University, New York, New York
| | - Tong Wang
- Department of Cellular and Molecular Physiology, Yale University, New Haven, Connecticut
| |
Collapse
|
8
|
Alexander RT, Dimke H. Molecular mechanisms underlying paracellular calcium and magnesium reabsorption in the proximal tubule and thick ascending limb. Ann N Y Acad Sci 2022; 1518:69-83. [PMID: 36200584 DOI: 10.1111/nyas.14909] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Calcium and magnesium are the most abundant divalent cations in the body. The plasma level is controlled by coordinated interaction between intestinal absorption, reabsorption in the kidney, and, for calcium at least, bone storage and exchange. The kidney adjusts urinary excretion of these ions in response to alterations in their systemic concentration. Free ionized and anion-complexed calcium and magnesium are filtered at the glomerulus. The majority (i.e., >85%) of filtered divalent cations are reabsorbed via paracellular pathways from the proximal tubule and thick ascending limb (TAL) of the loop of Henle. Interestingly, the largest fraction of filtered calcium is reabsorbed from the proximal tubule (65%), while the largest fraction of filtered magnesium is reclaimed from the TAL (60%). The paracellular pathways mediating these fluxes are composed of tight junctional pores formed by claudins. In the proximal tubule, claudin-2 and claudin-12 confer calcium permeability, while the exact identity of the magnesium pore remains to be determined. Claudin-16 and claudin-19 contribute to the calcium and magnesium permeable pathway in the TAL. In this review, we discuss the data supporting these conclusions and speculate as to why there is greater fractional calcium reabsorption from the proximal tubule and greater fractional magnesium reabsorption from the TAL.
Collapse
Affiliation(s)
- R Todd Alexander
- Departments of Physiology & Pediatrics, University of Alberta, Edmonton, Alberta, Canada.,Women's and Children's Health Institute, Edmonton, Alberta, Canada
| | - Henrik Dimke
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, Demark.,Department of Nephrology, Odense University Hospital, Odense, Denmark
| |
Collapse
|
9
|
Renal water transport in health and disease. Pflugers Arch 2022; 474:841-852. [PMID: 35678906 PMCID: PMC9338902 DOI: 10.1007/s00424-022-02712-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Revised: 05/11/2022] [Accepted: 05/19/2022] [Indexed: 12/12/2022]
Abstract
Saving body water by optimal reabsorption of water filtered by the kidney leading to excretion of urine with concentrations of solutes largely above that of plasma allowed vertebrate species to leave the aquatic environment to live on solid ground. Filtered water is reabsorbed for 70% and 20% by proximal tubules and thin descending limbs of Henle, respectively. These two nephron segments express the water channel aquaporin-1 located along both apical and basolateral membranes. In the proximal tubule, the paracellular pathway accounts for at least 30% of water reabsorption, and the tight-junction core protein claudin-2 plays a key role in this permeability. The ascending limb of Henle and the distal convoluted tubule are impermeant to water and are responsible for urine dilution. The water balance is adjusted along the collecting system, i.e. connecting tubule and the collecting duct, under the control of arginine-vasopressin (AVP). AVP is synthesized by the hypothalamus and released in response to an increase in extracellular osmolality or stimulation of baroreceptors by decreased blood pressure. In response to AVP, aquaporin-2 water channels stored in subapical intracellular vesicles are translocated to the apical plasma membrane and raise the water permeability of the collecting system. The basolateral step of water reabsorption is mediated by aquaporin-3 and -4, which are constitutively expressed. Drugs targeting water transport include classical diuretics, which primarily inhibit sodium transport; the new class of SGLT2 inhibitors, which promotes osmotic diuresis and the non-peptidic antagonists of the V2 receptor, which are pure aquaretic drugs. Disturbed water balance includes diabetes insipidus and hyponatremias. Diabetes insipidus is characterized by polyuria and polydipsia. It is either related to a deficit in AVP secretion called central diabetes insipidus that can be treated by AVP analogs or to a peripheral defect in AVP response called nephrogenic diabetes insipidus. Diabetes insipidus can be either of genetic origin or acquired. Hyponatremia is a common disorder most often related to free water excess relying on overstimulated or inappropriate AVP secretion. The assessment of blood volume is key for the diagnosis and treatment of hyponatremia, which can be classified as hypo-, eu-, or hypervolemic.
Collapse
|
10
|
López-Cayuqueo KI, Planells-Cases R, Pietzke M, Oliveras A, Kempa S, Bachmann S, Jentsch TJ. Renal Deletion of LRRC8/VRAC Channels Induces Proximal Tubulopathy. J Am Soc Nephrol 2022; 33:1528-1545. [PMID: 35777784 PMCID: PMC9342636 DOI: 10.1681/asn.2021111458] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Accepted: 05/13/2022] [Indexed: 01/25/2023] Open
Abstract
BACKGROUND Volume-regulated anion channels (VRACs) are heterohexamers of LRRC8A with LRRC8B, -C, -D, or -E in various combinations. Depending on the subunit composition, these swelling-activated channels conduct chloride, amino acids, organic osmolytes, and drugs. Despite VRACs' role in cell volume regulation, and large osmolarity changes in the kidney, neither the localization nor the function of VRACs in the kidney is known. METHODS Mice expressing epitope-tagged LRRC8 subunits were used to determine the renal localization of all VRAC subunits. Mice carrying constitutive deletions of Lrrc8b-e, or with inducible or cell-specific ablation of Lrrc8a, were analyzed to assess renal functions of VRACs. Analysis included histology, urine and serum parameters in different diuresis states, and metabolomics. RESULTS The kidney expresses all five VRAC subunits with strikingly distinct localization. Whereas LRRC8C is exclusively found in vascular endothelium, all other subunits are found in the nephron. LRRC8E is specific for intercalated cells, whereas LRRC8A, LRRC8B, and LRRC8D are prominent in basolateral membranes of proximal tubules. Conditional deletion of LRRC8A in proximal but not distal tubules and constitutive deletion of LRRC8D cause proximal tubular injury, increased diuresis, and mild Fanconi-like symptoms. CONCLUSIONS VRAC/LRRC8 channels are crucial for the function and integrity of proximal tubules, but not for more distal nephron segments despite their larger need for volume regulation. LRRC8A/D channels may be required for the basolateral exit of many organic compounds, including cellular metabolites, in proximal tubules. Proximal tubular injury likely results from combined accumulation of several transported molecules in the absence of VRAC channels.
Collapse
Affiliation(s)
- Karen I. López-Cayuqueo
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP) and Max-Delbrück-Centrum für Molekulare Medizin (MDC), Berlin, Germany
| | - Rosa Planells-Cases
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP) and Max-Delbrück-Centrum für Molekulare Medizin (MDC), Berlin, Germany
| | - Matthias Pietzke
- Integrative Metabolomics and Proteomics, Berlin Institute of Medical Systems Biology/Max-Delbrück-Centrum für Molekulare Medizin, Berlin, Germany
| | - Anna Oliveras
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP) and Max-Delbrück-Centrum für Molekulare Medizin (MDC), Berlin, Germany
| | - Stefan Kempa
- Integrative Metabolomics and Proteomics, Berlin Institute of Medical Systems Biology/Max-Delbrück-Centrum für Molekulare Medizin, Berlin, Germany
| | - Sebastian Bachmann
- Department of Anatomy, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Thomas J. Jentsch
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP) and Max-Delbrück-Centrum für Molekulare Medizin (MDC), Berlin, Germany,NeuroCure Centre of Excellence, Charité Universitätsmedizin Berlin, Berlin, Germany
| |
Collapse
|
11
|
Piossek F, Beneke S, Schlichenmaier N, Mucic G, Drewitz S, Dietrich DR. Physiological oxygen and co-culture with human fibroblasts facilitate in vivo-like properties in human renal proximal tubular epithelial cells. Chem Biol Interact 2022; 361:109959. [DOI: 10.1016/j.cbi.2022.109959] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Revised: 04/08/2022] [Accepted: 04/12/2022] [Indexed: 11/28/2022]
|
12
|
Abstract
Nephrolithiasis is a worldwide problem with increasing prevalence, enormous costs, and significant morbidity. Calcium-containing kidney stones are by far the most common kidney stones encountered in clinical practice. Consequently, hypercalciuria is the greatest risk factor for kidney stone formation. Hypercalciuria can result from enhanced intestinal absorption, increased bone resorption, or altered renal tubular transport. Kidney stone formation is complex and driven by high concentrations of calcium-oxalate or calcium-phosphate in the urine. After discussing the mechanism mediating renal calcium salt precipitation, we review recent discoveries in renal tubular calcium transport from the proximal tubule, thick ascending limb, and distal convolution. Furthermore, we address how calcium is absorbed from the intestine and mobilized from bone. The effect of acidosis on bone calcium resorption and urinary calcium excretion is also considered. Although recent discoveries provide insight into these processes, much remains to be understood in order to provide improved therapies for hypercalciuria and prevent kidney stone formation. Expected final online publication date for the Annual Review of Physiology, Volume 84 is February 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
Collapse
Affiliation(s)
- R T Alexander
- Departments of Physiology and Pediatrics, University of Alberta, Edmonton, Canada; .,Membrane Protein Disease Research Group, University of Alberta, Edmonton, Canada
| | - D G Fuster
- Department of Nephrology and Hypertension, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - H Dimke
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark.,Department of Nephrology, Odense University Hospital, Odense, Denmark
| |
Collapse
|
13
|
|
14
|
Larsen EH, Sørensen JN. Ion and Water Absorption by the Kidney Proximal Tubule: Computational Analysis of Isosmotic Transport. FUNCTION (OXFORD, ENGLAND) 2020; 1:zqaa014. [PMID: 35330635 PMCID: PMC8788719 DOI: 10.1093/function/zqaa014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Revised: 08/21/2020] [Accepted: 08/25/2020] [Indexed: 01/06/2023]
Affiliation(s)
- Erik H Larsen
- Department of Biology, University of Copenhagen, Copenhagen, Denmark,Address correspondence to E.H.L. (e-mail: )
| | - Jens N Sørensen
- Department of Wind Energy, Technical University of Denmark, Lyngby, Denmark
| |
Collapse
|
15
|
Abstract
Aquaporin (AQP) water channels are important in the function of the kidney. Constitutively expressed AQP1 in the proximal tubule and descending limb is important in normal fluid absorption and in the counter-current multiplication system. The vasopressin-regulated shuttling of AQP2 is essential in antidiuresis and the regulation of water balance. Genetic damage to AQPs, or pathological changes in expression or function, impair renal water handling. The most striking examples of this involve disruption of AQP2 function, which can result in profound nephrogenic diabetes insipidus. Aquaporin 1 is present in capillaries and venules and appears to be important in peritoneal dialysis, where it appears to represent the “ultrasmall pores” of the three-pore model. Decreased expression or function of AQP1 may be responsible for some cases of ultrafiltration failure, but further evidence will be required to establish whether this is the case.
Collapse
Affiliation(s)
- David Marples
- School of Biomedical Science, University of Leeds, United Kingdom
| |
Collapse
|
16
|
AQP1 expression in the proximal tubule of diabetic rat kidney. Heliyon 2020; 6:e03192. [PMID: 31956716 PMCID: PMC6956755 DOI: 10.1016/j.heliyon.2020.e03192] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Revised: 11/08/2019] [Accepted: 01/03/2020] [Indexed: 11/21/2022] Open
Abstract
Polyuria is a hallmark symptom and the first clinical manifestation of diabetes mellitus (DM). The glucose that remains in renal tubules was proposed to produce an osmotic effect resulting in polyuria. Although water is reabsorbed in proximal tubules through an aquaporin-1 (AQP1) dependent mechanism, AQP1 role in the genesis of polyuria is unknown. AQP1 expression was studied in a rat model of Type-1 DM at 15-days and 5-months of evolution. A different AQP1 expression pattern was found in both experimental groups, with no changes in AQP1 localization, suggesting that changes in AQP1 may be involved in the development of polyuria.
Collapse
|
17
|
Zhang J, Li S, Deng F, Baikeli B, Yu W, Liu G. Distribution of aquaporins and sodium transporters in the gastrointestinal tract of a desert hare, Lepus yarkandensis. Sci Rep 2019; 9:16639. [PMID: 31719660 PMCID: PMC6851143 DOI: 10.1038/s41598-019-53291-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Accepted: 10/30/2019] [Indexed: 01/16/2023] Open
Abstract
Lepus yarkandensis is a desert hare of the Tarim Basin in western China, and it has strong adaptability to arid environments. Aquaporins (AQPs) are a family of water channel proteins that facilitate transmembrane water transport. Gastrointestinal tract AQPs are involved in fluid absorption in the small intestine and colon. This study aimed to determine the distribution of AQPs and sodium transporters in the gastrointestinal tract of L. yarkandensis and to compare the expression of these proteins with that in Oryctolagus cuniculus. Immunohistochemistry was performed to analyse the cellular distribution of these proteins, and the acquired images were analysed with IpWin32 software. Our results revealed that AQP1 was located in the colonic epithelium, central lacteal cells, fundic gland parietal cells, and capillary endothelial cells; AQP3 was located in the colonic epithelium, small intestinal villus epithelium, gastric pit and fundic gland; AQP4 was located in the fundic gland, small intestinal gland and colonic epithelium; and epithelial sodium channel (ENaC) and Na+-K+-ATPase were located in the epithelial cells, respectively. The higher expression levels of AQP1, AQP3, ENaC and Na+-K+-ATPase in the colon of L. yarkandensis compared to those in O. cuniculus suggested that L. yarkandensis has a higher capacity for faecal dehydration.
Collapse
Affiliation(s)
- Jianping Zhang
- College of Life Science, Tarim University Alar, Xinjiang Province, 843300, People's Republic of China.
- Key Laboratory of Biological Resources Protection and Utilization in Tarim Basin, Tarim University Alar, Xinjiang Province, 843300, People's Republic of China.
- Department of Biochemistry and Molecular Biology, School of Laboratory Medicine, and Anhui Province Key Laboratory of Translational Cancer Research Bengbu Medical College Bengbu, Anhui Province, 233030, People's Republic of China.
| | - Shuwei Li
- College of Life Science, Tarim University Alar, Xinjiang Province, 843300, People's Republic of China
- Key Laboratory of Biological Resources Protection and Utilization in Tarim Basin, Tarim University Alar, Xinjiang Province, 843300, People's Republic of China
| | - Fang Deng
- College of Life Science, Tarim University Alar, Xinjiang Province, 843300, People's Republic of China
| | - Buheliqihan Baikeli
- College of Life Science, Tarim University Alar, Xinjiang Province, 843300, People's Republic of China
| | - Weijiang Yu
- College of Life Science, Tarim University Alar, Xinjiang Province, 843300, People's Republic of China
| | - Guoquan Liu
- Department of Biochemistry and Molecular Biology, School of Laboratory Medicine, and Anhui Province Key Laboratory of Translational Cancer Research Bengbu Medical College Bengbu, Anhui Province, 233030, People's Republic of China.
- Department of Basic Veterinary Medicine, and Key Lab of Swine Genetics and Breeding and Agricultural Animal Breeding and Reproduction, College of Animal Science and Veterinary Medicine Huazhong Agricultural University Wuhan, Hubei Province, 430070, People's Republic of China.
| |
Collapse
|
18
|
Feng J, Yan S, Chen Y, Han L, Wen L, Guo X, Wen Y, Li Y, He X, Han Z, Ren C, Jia Z, Guo Z, Zhai R, Wu J, Wen J. Aquaporin1-3 expression in normal and hydronephrotic kidneys in the human fetus. Pediatr Res 2019; 86:595-602. [PMID: 31261369 DOI: 10.1038/s41390-019-0485-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Revised: 06/06/2019] [Accepted: 06/16/2019] [Indexed: 11/09/2022]
Abstract
BACKGROUND Decreased expression of the renal aquaporin (AQP) protein family is associated with hydronephrosis in adult humans and animals. However, the expression of AQPs, especially subtypes AQP1-3, which play a core role in the urinary concentration function, in hydronephrotic human fetuses is not clear. The aim of this study is to investigate the expression of the AQP1-3 in normal and hydronephrotic human fetal kidneys. METHODS Twenty-one normal and six hydronephrotic kidney (HK) samples were harvested from abortive fetuses. Meanwhile, seven normal adult human kidney samples were collected as positive controls. Quantitative real-time PCR, western blotting, and immunohistochemistry were used to analyze the expression of AQP1-3. RESULTS Both the protein and messenger mRNA expression levels of AQP1-3 increased with gestational age in the normal fetuses, but the levels were significantly lower than those in the adult tissues and significantly higher than those in the hydronephrotic fetuses at the same gestational age. CONCLUSIONS The increased expression of AQP1-3 with gestational age in the fetal kidney may indicate maturation of the urinary concentrating ability. The lower expression of AQP1-3 in HKs may reflect a maturation obstacle with regard to urinary concentration in human hydronephrotic fetuses.
Collapse
Affiliation(s)
- Jinjin Feng
- Department of Pediatric Urodynamic Center and Henan Joint International Pediatric Urodynamic Laboratory, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, China
| | - Shaohua Yan
- Department of Pediatric Urodynamic Center and Henan Joint International Pediatric Urodynamic Laboratory, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, China
| | - Yan Chen
- Department of Pediatric Urodynamic Center and Henan Joint International Pediatric Urodynamic Laboratory, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, China
| | - Liping Han
- Department of Gynaecology and Obstetrics, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, China
| | - Lu Wen
- Department of Nephrology, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, China
| | - Xi Guo
- Department of Pediatric Urodynamic Center and Henan Joint International Pediatric Urodynamic Laboratory, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, China
| | - Yibo Wen
- Department of Pediatric Urodynamic Center and Henan Joint International Pediatric Urodynamic Laboratory, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, China
| | - Yunlong Li
- Department of Pediatric Urodynamic Center and Henan Joint International Pediatric Urodynamic Laboratory, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, China
| | - Xiangfei He
- Department of Pediatric Urodynamic Center and Henan Joint International Pediatric Urodynamic Laboratory, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, China
| | - Zhongjiang Han
- Department of Pediatric Urodynamic Center and Henan Joint International Pediatric Urodynamic Laboratory, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, China
| | - Chuanchuan Ren
- Department of Urology, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, China
| | - Zhiming Jia
- Department of Urology, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, China
| | - Zhan Guo
- Department of Urology, Children's Hospital of Henan Province, 450052, Zhengzhou, China
| | - Rongqun Zhai
- Department of Pediatric Urodynamic Center and Henan Joint International Pediatric Urodynamic Laboratory, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, China
| | - Junwei Wu
- Department of Nephrology, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, China
| | - Jianguo Wen
- Department of Pediatric Urodynamic Center and Henan Joint International Pediatric Urodynamic Laboratory, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, China.
| |
Collapse
|
19
|
Rezzani R, Franco C, Favero G, Rodella LF. Ghrelin-mediated pathway in Apolipoprotein-E deficient mice: a survival system. Am J Transl Res 2019; 11:4263-4276. [PMID: 31396333 PMCID: PMC6684914] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Accepted: 06/18/2019] [Indexed: 06/10/2023]
Abstract
Renal diseases interfere with the regulation of several metabolic pathways including dyslipidemia. The latter includes increased triglycerides, very low-density lipoprotein levels and decreased high-density lipoproteins. These lipoproteins change during renal injury. Apolipoprotein-E deficient mice (ApoE-/-) are considered a very well accepted model of hypercholesterolemia with marked renal pathological alterations. Ghrelin hormone is mainly secreted from the stomach when the stomach is empty, but it is also found in the kidney. In this organ it has autocrine and/or paracrine roles determining glomerular filtration rate, tubular phosphate and sodium reabsorption. Interestingly, it has been demonstrated that ghrelin levels increase after fasting. This mechanism induces an interaction with sirtuin 1 (SIRT1)/p53 pathway suggesting a link between ghrelin and SIRT1 in the regulation of salt and water metabolism. The mechanisms of ghrelin-induced SIRT1 expression are not yet fully understood. Recent studies indicate that SIRT1 exerts renoprotective properties against kidney diseases. This could be a very interesting point for underlining the important role of the ghrelin-SIRT1 system. Water movement across biological cell membranes is enhanced or facilitated by tetrameric membrane-bound channels, named aquaporin (AQP) family, and in particular, AQP1 and AQP2 proteins. In this study, we evaluated the possible pathway existing among the ghrelin/SIRT1/AQP1/AQP2 system in APOE-/- mice in order to clarify or stress the role played by said system in renal diseases associated to aging with or without comorbities. The results could provide a basis for considering ghrelin as a new target for therapeutic strategies of renal injury.
Collapse
Affiliation(s)
- Rita Rezzani
- Anatomy and Physiopathology Division, Department of Clinical and Experimental Sciences, University of BresciaBrescia, Italy
- Interdipartimental University Center of Research “Adaptation and Regeneration of Tissues and Organs-(ARTO)”, University of BresciaBrescia 25123, Italy
| | - Caterina Franco
- Anatomy and Physiopathology Division, Department of Clinical and Experimental Sciences, University of BresciaBrescia, Italy
| | - Gaia Favero
- Anatomy and Physiopathology Division, Department of Clinical and Experimental Sciences, University of BresciaBrescia, Italy
| | - Luigi F Rodella
- Anatomy and Physiopathology Division, Department of Clinical and Experimental Sciences, University of BresciaBrescia, Italy
- Interdipartimental University Center of Research “Adaptation and Regeneration of Tissues and Organs-(ARTO)”, University of BresciaBrescia 25123, Italy
| |
Collapse
|
20
|
Jung HJ, Kwon TH. New insights into the transcriptional regulation of aquaporin-2 and the treatment of X-linked hereditary nephrogenic diabetes insipidus. Kidney Res Clin Pract 2019; 38:145-158. [PMID: 31189221 PMCID: PMC6577206 DOI: 10.23876/j.krcp.19.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Revised: 02/09/2019] [Accepted: 02/11/2019] [Indexed: 12/18/2022] Open
Abstract
The kidney collecting duct (CD) is a tubular segment of the kidney where the osmolality and final flow rate of urine are established, enabling urine concentration and body water homeostasis. Water reabsorption in the CD depends on the action of arginine vasopressin (AVP) and a transepithelial osmotic gradient between the luminal fluid and surrounding interstitium. AVP induces transcellular water reabsorption across CD principal cells through associated signaling pathways after binding to arginine vasopressin receptor 2 (AVPR2). This signaling cascade regulates the water channel protein aquaporin-2 (AQP2). AQP2 is exclusively localized in kidney connecting tubules and CDs. Specifically, AVP stimulates the intracellular translocation of AQP2-containing vesicles to the apical plasma membrane, increasing the osmotic water permeability of CD cells. Moreover, AVP induces transcription of the Aqp2 gene, increasing AQP2 protein abundance. This review provides new insights into the transcriptional regulation of the Aqp2 gene in the kidney CD with an overview of AVP and AQP2. It summarizes current therapeutic approaches for X-linked nephrogenic diabetes insipidus caused by AVPR2 gene mutations.
Collapse
Affiliation(s)
- Hyun Jun Jung
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Tae-Hwan Kwon
- Department of Biochemistry and Cell Biology, School of Medicine, Kyungpook National University, Daegu, Korea
| |
Collapse
|
21
|
Physiological and pathological impact of AQP1 knockout in mice. Biosci Rep 2019; 39:BSR20182303. [PMID: 31023968 PMCID: PMC6522737 DOI: 10.1042/bsr20182303] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2018] [Revised: 04/21/2019] [Accepted: 04/24/2019] [Indexed: 01/04/2023] Open
Abstract
Aquaporin 1 (AQP1) is a glycoprotein responsible for water passive transport quickly across biological membrane. Here, we reviewed the structural and functional impacts of AQP1 knockout (AQP1-KO) in animal or cell culture models. AQP1 gene deletion can cause a large number of abnormalities including the disturbance in epithelial fluid secretion, polyhydramnios, deficiency of urinary concentrating function, and impairment of pain perception. AQP1-KO mice also displayed aberrations of cardiovascular, gastrointestinal and hepatobiliary, and kidney functions as well as placenta and embryo development. Moreover, AQP1-KO perturbed tumor angiogenesis and led to reduced brain injury upon trauma. On the cellular level, AQP1-KO caused neuroinflammation, aberrant cell proliferation and migration, and macrophages infiltration. Mechanistic studies confirmed that AQP1 gene products regulate the secretory function and participated in balancing the osmotic water flux across the peritoneal membrane. The available data indicated that AQP1 might serve as a potential target for developing novel therapeutic approaches against diverse human diseases.
Collapse
|
22
|
Chen C, Wang S, Chen J, Liu X, Zhang M, Wang X, Xu W, Zhang Y, Li H, Pan X, Si M. Escin suppresses HMGB1-induced overexpression of aquaporin-1 and increased permeability in endothelial cells. FEBS Open Bio 2019; 9:891-900. [PMID: 30972964 PMCID: PMC6487832 DOI: 10.1002/2211-5463.12622] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2018] [Revised: 01/16/2019] [Accepted: 02/07/2019] [Indexed: 12/11/2022] Open
Abstract
Escin, a natural triterpene saponin mixture obtained from the horse chestnut tree (Aesculus hippocastanum), has been used for the treatment of chronic venous insufficiency (CVI), hemorrhoids, and edema. However, it is unclear how escin protects against endothelial barrier dysfunction induced by pro‐inflammatory high mobility group protein 1 (HMGB1). Here, we report that escin can suppress (a) HMGB1‐induced overexpression of the aquaporin‐1 (AQP1) water channel in endothelial cells and (b) HMGB1‐induced increases in endothelial cell permeability. This is the first report that escin inhibits AQP1 and alleviates barrier dysfunction in HMGB1‐induced inflammatory response.
Collapse
Affiliation(s)
- Changjun Chen
- Department of Orthopedics, Qilu Hospital of Shandong University, Jinan, China
| | - Songgang Wang
- Department of Orthopedics, Qilu Hospital of Shandong University, Jinan, China
| | - Jiying Chen
- The Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education, Chinese Ministry of Health, the State Shandong Province Joint Key Laboratory of Translational Cardiovascular Medicine, Qilu Hospital of Shandong University, Jinan, Shandong, China
| | - Xiaolin Liu
- The Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education, Chinese Ministry of Health, the State Shandong Province Joint Key Laboratory of Translational Cardiovascular Medicine, Qilu Hospital of Shandong University, Jinan, Shandong, China
| | - Mengchen Zhang
- Department of Orthopedics, Qilu Hospital of Shandong University, Jinan, China
| | - Xi Wang
- Department of Orthopedics, Qilu Hospital of Shandong University, Jinan, China
| | - Weihua Xu
- Department of Orthopedics, Qilu Hospital of Shandong University, Jinan, China
| | - Yayun Zhang
- Department of Orthopedics, Qilu Hospital of Shandong University, Jinan, China
| | - Hao Li
- Department of Orthopedics, Qilu Hospital of Shandong University, Jinan, China
| | - Xin Pan
- Department of Orthopedics, Qilu Hospital of Shandong University, Jinan, China
| | - Meng Si
- Department of Orthopedics, Qilu Hospital of Shandong University, Jinan, China
| |
Collapse
|
23
|
Abstract
Renal tubular acidosis should be suspected in poorly thriving young children with hyperchloremic and hypokalemic normal anion gap metabolic acidosis, with/without syndromic features. Further workup is needed to determine the type of renal tubular acidosis and the presumed etiopathogenesis, which informs treatment choices and prognosis. The risk of nephrolithiasis and calcinosis is linked to the presence (proximal renal tubular acidosis, negligible stone risk) or absence (distal renal tubular acidosis, high stone risk) of urine citrate excretion. New formulations of slow-release alkali and potassium combination supplements are being tested that are expected to simplify treatment and lead to sustained acidosis correction.
Collapse
Affiliation(s)
- Robert Todd Alexander
- Department of Pediatrics and Physiology, Stollery Children's Hospital, 11405-87 Avenue, Edmonton, Alberta T6G 1C9, Canada
| | - Martin Bitzan
- Division of Nephrology, Department of Pediatrics, The Montreal Children's Hospital, McGill University Health Centre, Room B RC.6651, Montreal, Quebec H4A 3J1, Canada; Al Jalila Children's Hospital, Al Jadaf PO Box 7662, Dubai, UAE.
| |
Collapse
|
24
|
Vitamin D Regulates the Expressions of AQP-1 and AQP-4 in Mice Kidneys. BIOMED RESEARCH INTERNATIONAL 2019; 2019:3027036. [PMID: 30809535 PMCID: PMC6369492 DOI: 10.1155/2019/3027036] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Revised: 12/09/2018] [Accepted: 01/08/2019] [Indexed: 01/27/2023]
Abstract
Aim Vitamin D plays an important role in water and salt homeostasis. The aim of our study was to investigate the underlying relationship of Vitamin D and Aquaporins (AQP). Methods The behaviors of 1α (OH)-ase knockout mice and wild type mice were observed before analysis. The ICR mice were treated with vehicle or paricalcitol, a vitamin D analogue, followed by animals receiving a standard diet and free access to drinking water either with aliskiren (renin blocker; 37.5 mg aliskiren in 100 ml water), or telmisartan (a angiotensin II type I receptor blocker; 40 mg telmisartan in 100 ml water) a week before study. The expressions of AQP-1, AQP-4, and renin in mice kidneys were detected by western bolting, immunohistochemistry, and immunofluorescence. Results Diuresis and polydipsia were observed in 1α (OH)-ase knockout mice, and a decreased water intake and urine output in ICR mice was observed after paricalcitol treatment. Compared with wild type, the AQP-1 expressions were increased in renal papilla and AQP-4 expressions were decreased in renal proximal tubule of 1α(OH) ase knockout mice. In addition, AQP-1 was decreased in renal papilla and AQP-4 expressions were increased in proximal tubule by suppressing renin activity or supplement of Vitamin D analogue. After injecting renin into the lateral ventricle of the 1α(OH)ase knockout mice, the renin expression level was decreased in the kidney, followed by the decrease of AQP-1 in renal papilla and increase of AQP-4 in proximal tubule. Conclusions Overall, Vitamin D and renin inhibitors have synergistic effects in regulating water channels in mice kidneys.
Collapse
|
25
|
Sisto M, Ribatti D, Lisi S. Aquaporin water channels: New perspectives on the potential role in inflammation. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2019; 116:311-345. [PMID: 31036295 DOI: 10.1016/bs.apcsb.2018.11.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Aquaporins (AQPs) are a family of membrane water channel proteins that osmotically modulate water fluid homeostasis in several tissues; some of them also transport small solutes such as glycerol. At the cellular level, the AQPs regulate not only cell migration and transepithelial fluid transport across membranes, but also common events that are crucial for the inflammatory response. Emerging data reveal a new function of AQPs in the inflammatory process, as demonstrated by their dysregulation in a wide range of inflammatory diseases including edematous states, cancer, obesity, wound healing and several autoimmune diseases. This chapter summarizes the discoveries made so far about the structure and functions of the AQPs and provides updated information on the underlying mechanisms of AQPs in several human inflammatory diseases. The discovery of new functions for AQPs opens new vistas offering promise for the discovery of mechanisms and therapeutic opportunities in inflammatory disorders.
Collapse
Affiliation(s)
- Margherita Sisto
- Department of Basic Medical Sciences, Neurosciences and Sensory Organs (SMBNOS), Section of Human Anatomy and Histology, University of Bari "Aldo Moro", Bari, Italy.
| | - Domenico Ribatti
- Department of Basic Medical Sciences, Neurosciences and Sensory Organs (SMBNOS), Section of Human Anatomy and Histology, University of Bari "Aldo Moro", Bari, Italy
| | - Sabrina Lisi
- Department of Basic Medical Sciences, Neurosciences and Sensory Organs (SMBNOS), Section of Human Anatomy and Histology, University of Bari "Aldo Moro", Bari, Italy
| |
Collapse
|
26
|
Larsen EH, Sørensen JN. Stationary and Nonstationary Ion and Water Flux Interactions in Kidney Proximal Tubule: Mathematical Analysis of Isosmotic Transport by a Minimalistic Model. Rev Physiol Biochem Pharmacol 2019; 177:101-147. [DOI: 10.1007/112_2019_16] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
AbstractOur mathematical model of epithelial transport (Larsen et al. Acta Physiol. 195:171–186, 2009) is extended by equations for currents and conductance of apical SGLT2. With independent variables of the physiological parameter space, the model reproduces intracellular solute concentrations, ion and water fluxes, and electrophysiology of proximal convoluted tubule. The following were shown:Water flux is given by active Na+flux into lateral spaces, while osmolarity of absorbed fluid depends on osmotic permeability of apical membranes.Following aquaporin “knock-out,” water uptake is not reduced but redirected to the paracellular pathway.Reported decrease in epithelial water uptake in aquaporin-1 knock-out mouse is caused by downregulation of active Na+absorption.Luminal glucose stimulates Na+uptake by instantaneous depolarization-induced pump activity (“cross-talk”) and delayed stimulation because of slow rise in intracellular [Na+].Rate of fluid absorption and flux of active K+absorption would have to be attuned at epithelial cell level for the [K+] of the absorbate being in the physiological range of interstitial [K+].Following unilateral osmotic perturbation, time course of water fluxes between intraepithelial compartments provides physical explanation for the transepithelial osmotic permeability being orders of magnitude smaller than cell membranes’ osmotic permeability.Fluid absorption is always hyperosmotic to bath.Deviation from isosmotic absorption is increased in presence of glucose contrasting experimental studies showing isosmotic transport being independent of glucose uptake.For achieving isosmotic transport, the cost of Na+recirculation is predicted to be but a few percent of the energy consumption of Na+/K+pumps.
Collapse
|
27
|
Li Q, McDonough AA, Layton HE, Layton AT. Functional implications of sexual dimorphism of transporter patterns along the rat proximal tubule: modeling and analysis. Am J Physiol Renal Physiol 2018; 315:F692-F700. [PMID: 29846110 PMCID: PMC6172582 DOI: 10.1152/ajprenal.00171.2018] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Revised: 05/14/2018] [Accepted: 05/22/2018] [Indexed: 01/07/2023] Open
Abstract
The goal of this study is to investigate the functional implications of the sexual dimorphism in transporter patterns along the proximal tubule. To do so, we have developed sex-specific computational models of solute and water transport in the proximal convoluted tubule of the rat kidney. The models account for the sex differences in expression levels of the apical and basolateral transporters, in single-nephron glomerular filtration rate, and in tubular dimensions. Model simulations predict that 70.6 and 38.7% of the filtered volume is reabsorbed by the proximal tubule of the male and female rat kidneys, respectively. The lower fractional volume reabsorption in females can be attributed to their smaller transport area and lower aquaporin-1 expression level. The latter also results in a larger contribution of the paracellular pathway to water transport. Correspondingly similar fractions (70.9 and 39.2%) of the filtered Na+ are reabsorbed by the male and female proximal tubule models, respectively. The lower fractional Na+ reabsorption in females is due primarily to their smaller transport area and lower Na+/H+ exchanger isoform 3 and claudin-2 expression levels. Notably, unlike most Na+ transporters, whose expression levels are lower in females, Na+-glucose cotransporter 2 (SGLT2) expression levels are 2.5-fold higher in females. Model simulations suggest that the higher SGLT2 expression in females may compensate for their lower tubular transport area to achieve a hyperglycemic tolerance similar to that of males.
Collapse
Affiliation(s)
- Qianyi Li
- Kuang Yaming Honors School, Nanjing University , Nanjing , China
| | - Alicia A McDonough
- Department of Integrative Anatomical Sciences, Kerck School of Medicine, University of Southern California , Los Angeles, California
| | - Harold E Layton
- Department of Mathematics, Duke University , Durham, North Carolina
| | - Anita T Layton
- Department of Mathematics, Duke University , Durham, North Carolina
- Departments of Biomedical Engineering and Medicine, Duke University , Durham, North Carolina
- Department of Applied Mathematics, University of Waterloo , Waterloo, Ontario , Canada
| |
Collapse
|
28
|
Marable SS, Chung E, Adam M, Potter SS, Park JS. Hnf4a deletion in the mouse kidney phenocopies Fanconi renotubular syndrome. JCI Insight 2018; 3:97497. [PMID: 30046000 PMCID: PMC6124415 DOI: 10.1172/jci.insight.97497] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Accepted: 06/19/2018] [Indexed: 12/21/2022] Open
Abstract
Different nephron tubule segments perform distinct physiological functions, collectively acting as a blood filtration unit. Dysfunction of the proximal tubule segment can lead to Fanconi renotubular syndrome (FRTS), with major symptoms such as excess excretion of water, glucose, and phosphate in the urine. It has been shown that a mutation in HNF4A is associated with FRTS in humans and that Hnf4a is expressed specifically in proximal tubules in adult rat nephrons. However, little is known about the role of Hnf4a in nephrogenesis. Here, we found that Hnf4a is expressed in both presumptive and differentiated proximal tubules in the developing mouse kidney. We show that Hnf4a is required for the formation of differentiated proximal tubules but is dispensable for the formation of presumptive proximal tubules. Furthermore, we show that loss of Hnf4a decreased the expression of proximal tubule-specific genes. Adult Hnf4a mutant mice presented with FRTS-like symptoms, including polyuria, polydipsia, glycosuria, and phosphaturia. Analysis of the adult Hnf4a mutant kidney also showed proximal tubule dysgenesis and nephrocalcinosis. Our results demonstrate the critical role of Hnf4a in proximal tubule development and provide mechanistic insight into the etiology of FRTS.
Collapse
Affiliation(s)
- Sierra S. Marable
- Division of Pediatric Urology and
- Division of Developmental Biology, Cincinnati Children’s Hospital Medical Center (CCHMC), Cincinnati, Ohio, USA
| | | | - Mike Adam
- Division of Developmental Biology, Cincinnati Children’s Hospital Medical Center (CCHMC), Cincinnati, Ohio, USA
| | - S. Steven Potter
- Division of Developmental Biology, Cincinnati Children’s Hospital Medical Center (CCHMC), Cincinnati, Ohio, USA
| | - Joo-Seop Park
- Division of Pediatric Urology and
- Division of Developmental Biology, Cincinnati Children’s Hospital Medical Center (CCHMC), Cincinnati, Ohio, USA
| |
Collapse
|
29
|
Venglovecz V, Pallagi P, Kemény LV, Balázs A, Balla Z, Becskeházi E, Gál E, Tóth E, Zvara Á, Puskás LG, Borka K, Sendler M, Lerch MM, Mayerle J, Kühn JP, Rakonczay Z, Hegyi P. The Importance of Aquaporin 1 in Pancreatitis and Its Relation to the CFTR Cl - Channel. Front Physiol 2018; 9:854. [PMID: 30050452 PMCID: PMC6052342 DOI: 10.3389/fphys.2018.00854] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2018] [Accepted: 06/15/2018] [Indexed: 12/17/2022] Open
Abstract
Aquaporins (AQPs) facilitate the transepithelial water flow involved in epithelial fluid secretion in numerous tissues; however, their function in the pancreas is less characterized. Acute pancreatitis (AP) is a serious disorder in which specific treatment is still not possible. Accumulating evidence indicate that decreased pancreatic ductal fluid secretion plays an essential role in AP; therefore, the aim of this study was to investigate the physiological and pathophysiological role of AQPs in the pancreas. Expression and localization of AQPs were investigated by real-time PCR and immunocytochemistry, whereas osmotic transmembrane water permeability was estimated by the dye dilution technique, in Capan-1 cells. The presence of AQP1 and CFTR in the mice and human pancreas were investigated by immunohistochemistry. Pancreatic ductal HCO3- and fluid secretion were studied on pancreatic ducts isolated from wild-type (WT) and AQP1 knock out (KO) mice using microfluorometry and videomicroscopy, respectively. In vivo pancreatic fluid secretion was estimated by magnetic resonance imaging. AP was induced by intraperitoneal injection of cerulein and disease severity was assessed by measuring biochemical and histological parameters. In the mice, the presence of AQP1 was detected throughout the whole plasma membrane of the ductal cells and its expression highly depends on the presence of CFTR Cl- channel. In contrast, the expression of AQP1 is mainly localized to the apical membrane of ductal cells in the human pancreas. Bile acid treatment dose- and time-dependently decreased mRNA and protein expression of AQP1 and reduced expression of this channel was also demonstrated in patients suffering from acute and chronic pancreatitis. HCO3- and fluid secretion significantly decreased in AQP1 KO versus WT mice and the absence of AQP1 also worsened the severity of pancreatitis. Our results suggest that AQP1 plays an essential role in pancreatic ductal fluid and HCO3- secretion and decreased expression of the channel alters fluid secretion which probably contribute to increased susceptibility of the pancreas to inflammation.
Collapse
Affiliation(s)
- Viktória Venglovecz
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
| | - Petra Pallagi
- First Department of Medicine, University of Szeged, Szeged, Hungary
| | - Lajos V Kemény
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
| | - Anita Balázs
- First Department of Medicine, University of Szeged, Szeged, Hungary
| | - Zsolt Balla
- Department of Pathophysiology, University of Szeged, Szeged, Hungary
| | - Eszter Becskeházi
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
| | - Eleonóra Gál
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
| | - Emese Tóth
- First Department of Medicine, University of Szeged, Szeged, Hungary
| | - Ágnes Zvara
- Laboratory of Functional Genomics, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary
| | - László G Puskás
- Laboratory of Functional Genomics, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary
| | - Katalin Borka
- Second Department of Pathology, Semmelweis University, Budapest, Hungary
| | - Matthias Sendler
- Department of Medicine A, University Medicine Greifswald, University of Greifswald, Greifswald, Germany
| | - Markus M Lerch
- Department of Medicine A, University Medicine Greifswald, University of Greifswald, Greifswald, Germany
| | - Julia Mayerle
- Department of Medicine A, University Medicine Greifswald, University of Greifswald, Greifswald, Germany.,Department of Medicine II, Klinikum Grosshadern, Universitätsklinikum der Ludwig-Maximilians-Universität München, Munich, Germany
| | - Jens-Peter Kühn
- Institute of Radiology, University Medicine Greifswald, University of Greifswald, Greifswald, Germany.,Institute and Policlinic of Radiology, University Hospital Carl Gustav Carus, TU Dresden, Dresden, Germany
| | - Zoltán Rakonczay
- Department of Pathophysiology, University of Szeged, Szeged, Hungary
| | - Péter Hegyi
- First Department of Medicine, University of Szeged, Szeged, Hungary.,MTA-SZTE Translational Gastroenterology Research Group, University of Szeged, Szeged, Hungary.,Institute for Translational Medicine and First Department of Medicine, Medical School, University of Pécs, Pécs, Hungary
| |
Collapse
|
30
|
|
31
|
De Ieso ML, Yool AJ. Mechanisms of Aquaporin-Facilitated Cancer Invasion and Metastasis. Front Chem 2018; 6:135. [PMID: 29922644 PMCID: PMC5996923 DOI: 10.3389/fchem.2018.00135] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Accepted: 04/09/2018] [Indexed: 01/02/2023] Open
Abstract
Cancer is a leading cause of death worldwide, and its incidence is rising with numbers expected to increase 70% in the next two decades. The fact that current mainline treatments for cancer patients are accompanied by debilitating side effects prompts a growing demand for new therapies that not only inhibit growth and proliferation of cancer cells, but also control invasion and metastasis. One class of targets gaining international attention is the aquaporins, a family of membrane-spanning water channels with diverse physiological functions and extensive tissue-specific distributions in humans. Aquaporins−1,−2,−3,−4,−5,−8, and−9 have been linked to roles in cancer invasion, and metastasis, but their mechanisms of action remain to be fully defined. Aquaporins are implicated in the metastatic cascade in processes of angiogenesis, cellular dissociation, migration, and invasion. Cancer invasion and metastasis are proposed to be potentiated by aquaporins in boosting tumor angiogenesis, enhancing cell volume regulation, regulating cell-cell and cell-matrix adhesions, interacting with actin cytoskeleton, regulating proteases and extracellular-matrix degrading molecules, contributing to the regulation of epithelial-mesenchymal transitions, and interacting with signaling pathways enabling motility and invasion. Pharmacological modulators of aquaporin channels are being identified and tested for therapeutic potential, including compounds derived from loop diuretics, metal-containing organic compounds, plant natural products, and other small molecules. Further studies on aquaporin-dependent functions in cancer metastasis are needed to define the differential contributions of different classes of aquaporin channels to regulation of fluid balance, cell volume, small solute transport, signal transduction, their possible relevance as rate limiting steps, and potential values as therapeutic targets for invasion and metastasis.
Collapse
Affiliation(s)
- Michael L De Ieso
- Department of Physiology, Adelaide Medical School, University of Adelaide, Adelaide, SA, Australia
| | - Andrea J Yool
- Department of Physiology, Adelaide Medical School, University of Adelaide, Adelaide, SA, Australia
| |
Collapse
|
32
|
AKAPs-PKA disruptors increase AQP2 activity independently of vasopressin in a model of nephrogenic diabetes insipidus. Nat Commun 2018; 9:1411. [PMID: 29650969 PMCID: PMC5897355 DOI: 10.1038/s41467-018-03771-2] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Accepted: 03/09/2018] [Indexed: 02/08/2023] Open
Abstract
Congenital nephrogenic diabetes insipidus (NDI) is characterized by the inability of the kidney to concentrate urine. Congenital NDI is mainly caused by loss-of-function mutations in the vasopressin type 2 receptor (V2R), leading to impaired aquaporin-2 (AQP2) water channel activity. So far, treatment options of congenital NDI either by rescuing mutant V2R with chemical chaperones or by elevating cyclic adenosine monophosphate (cAMP) levels have failed to yield effective therapies. Here we show that inhibition of A-kinase anchoring proteins (AKAPs) binding to PKA increases PKA activity and activates AQP2 channels in cortical collecting duct cells. In vivo, the low molecular weight compound 3,3′-diamino-4,4′-dihydroxydiphenylmethane (FMP-API-1) and its derivatives increase AQP2 activity to the same extent as vasopressin, and increase urine osmolality in the context of V2R inhibition. We therefore suggest that FMP-API-1 may constitute a promising lead compound for the treatment of congenital NDI caused by V2R mutations. Patients suffering from congenital nephrogenic diabetes insipidus (NDI) fail to concentrate urine due to mutations in vasopressin type 2 receptor (V2R). Here Ando et al. show that agents disrupting the interaction between PKA and AKAPs restore aquaporin-2 activity downstream of V2R, offering a therapeutic approach for the treatment of NDI.
Collapse
|
33
|
Liu M, Sun Y, Xu M, Yu X, Zhang Y, Huang S, Ding G, Zhang A, Jia Z. Role of mitochondrial oxidative stress in modulating the expressions of aquaporins in obstructive kidney disease. Am J Physiol Renal Physiol 2018; 314:F658-F666. [PMID: 29357430 DOI: 10.1152/ajprenal.00234.2017] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Downregulation of aquaporins (AQPs) in obstructive kidney disease has been well demonstrated with elusive mechanisms. Our previous study indicated that mitochondrial dysfunction played a crucial role in this process. However, it is still uncertain how mitochondrial dysfunction affected the AQPs in obstructive kidney disease. This study investigated the role of mitochondria-derived oxidative stress in mediating obstruction-induced downregulation of AQPs. After unilateral ureteral obstruction for 7 days, renal superoxide dismutase 2 (SOD2; mitochondria-specific SOD) was reduced by 85%. Meanwhile, AQP1, AQP2, AQP3, and AQP4 were remarkably downregulated as determined by Western blotting and/or quantitative real-time PCR. Administration of the SOD2 mimic manganese (III) tetrakis(4-benzoic acid)porphyrin chloride (MnTBAP) significantly attenuated AQP2 downregulation in line with complete blockade of thiobarbituric acid-reactive substances elevation, whereas the reduction of AQP1, AQP3, and AQP4 was not affected. The cyclooxygenase (COX)-2/prostaglandin (PG) E2 pathway has been well documented as a contributor of AQP reduction in obstructed kidney; thus, we detected the levels of COX-1/2 and microsomal prostaglandin E synthase 1 (mPGES-1) in kidney and PGE2 secretion in urine. Significantly, MnTBAP partially suppressed the elevation of COX-2, mPGES-1, and PGE2. Moreover, a marked decrease of V2 receptor was significantly restored after MnTBAP treatment. However, the fibrotic response and renal tubular damage were unaffected by MnTBAP in obstructed kidneys. Collectively, these findings suggested an important role of mitochondrial oxidative stress in mediating AQP2 downregulation in obstructed kidney, possibly via modulating the COX-2/mPGES-1/PGE2/V2 receptor pathway.
Collapse
Affiliation(s)
- Mi Liu
- Nanjing Key Laboratory of Pediatrics, Children’s Hospital of Nanjing Medical University, Nanjing, China
- Department of Cardiology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China
| | - Ying Sun
- Nanjing Key Laboratory of Pediatrics, Children’s Hospital of Nanjing Medical University, Nanjing, China
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, Xuzhou Medical University, Xuzhou, China
| | - Man Xu
- Nanjing Key Laboratory of Pediatrics, Children’s Hospital of Nanjing Medical University, Nanjing, China
- Department of Nephrology, Children’s Hospital of Nanjing Medical University, Nanjing, China
- Jiangsu Key Laboratory of Pediatrics, Nanjing Medical University, Nanjing, China
| | - Xiaowen Yu
- Nanjing Key Laboratory of Pediatrics, Children’s Hospital of Nanjing Medical University, Nanjing, China
- Department of Nephrology, Children’s Hospital of Nanjing Medical University, Nanjing, China
- Jiangsu Key Laboratory of Pediatrics, Nanjing Medical University, Nanjing, China
| | - Yue Zhang
- Nanjing Key Laboratory of Pediatrics, Children’s Hospital of Nanjing Medical University, Nanjing, China
- Department of Nephrology, Children’s Hospital of Nanjing Medical University, Nanjing, China
- Jiangsu Key Laboratory of Pediatrics, Nanjing Medical University, Nanjing, China
| | - Songming Huang
- Nanjing Key Laboratory of Pediatrics, Children’s Hospital of Nanjing Medical University, Nanjing, China
- Department of Nephrology, Children’s Hospital of Nanjing Medical University, Nanjing, China
- Jiangsu Key Laboratory of Pediatrics, Nanjing Medical University, Nanjing, China
| | - Guixia Ding
- Nanjing Key Laboratory of Pediatrics, Children’s Hospital of Nanjing Medical University, Nanjing, China
- Department of Nephrology, Children’s Hospital of Nanjing Medical University, Nanjing, China
- Jiangsu Key Laboratory of Pediatrics, Nanjing Medical University, Nanjing, China
| | - Aihua Zhang
- Nanjing Key Laboratory of Pediatrics, Children’s Hospital of Nanjing Medical University, Nanjing, China
- Department of Nephrology, Children’s Hospital of Nanjing Medical University, Nanjing, China
- Jiangsu Key Laboratory of Pediatrics, Nanjing Medical University, Nanjing, China
| | - Zhanjun Jia
- Nanjing Key Laboratory of Pediatrics, Children’s Hospital of Nanjing Medical University, Nanjing, China
- Department of Nephrology, Children’s Hospital of Nanjing Medical University, Nanjing, China
- Jiangsu Key Laboratory of Pediatrics, Nanjing Medical University, Nanjing, China
| |
Collapse
|
34
|
Tradtrantip L, Jin BJ, Yao X, Anderson MO, Verkman AS. Aquaporin-Targeted Therapeutics: State-of-the-Field. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 969:239-250. [PMID: 28258578 DOI: 10.1007/978-94-024-1057-0_16] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Drugs targeting aquaporins have broad potential clinical applications, including cancer, obesity, edema, glaucoma, skin diseases and others. The astrocyte water channel aquaporin-4 is a particularly compelling target because of its role of brain water movement, neuroexcitation and glia scarring, and because it is the target of pathogenic autoantibodies in the neuroinflammatory demyelinating disease neuromyelitis optica . There has been considerable interest in the identification of small molecule inhibitors of aquaporins, with various candidates emerging from testing of known ion transport inhibitors, as well as compound screening and computational chemistry. However, in general, the activity of reported aquaporin inhibitors has not been confirmed on retesting, which may be due to technical problems in water transport assays used in the original identification studies, and the challenges in modulating the activity of small, compact, pore-containing membrane proteins. We review here the state of the field of aquaporin-modulating small molecules and biologics, and the challenges and opportunities in moving forward.
Collapse
Affiliation(s)
- Lukmanee Tradtrantip
- Departments of Medicine and Physiology, University of California, San Francisco, CA, 94143-0521, USA
| | - Bjung-Ju Jin
- Departments of Medicine and Physiology, University of California, San Francisco, CA, 94143-0521, USA
| | - Xiaoming Yao
- Departments of Medicine and Physiology, University of California, San Francisco, CA, 94143-0521, USA
| | - Marc O Anderson
- Department of Chemistry and Biochemistry, San Francisco State University, San Francisco, CA, 94132-4136, USA
| | - Alan S Verkman
- Departments of Medicine and Physiology, University of California, San Francisco, CA, 94143-0521, USA.
| |
Collapse
|
35
|
Sutka M, Amodeo G, Ozu M. Plant and animal aquaporins crosstalk: what can be revealed from distinct perspectives. Biophys Rev 2017; 9:545-562. [PMID: 28871493 DOI: 10.1007/s12551-017-0313-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Accepted: 08/02/2017] [Indexed: 01/03/2023] Open
Abstract
Aquaporins (AQPs) can be revisited from a distinct and complementary perspective: the outcome from analyzing them from both plant and animal studies. (1) The approach in the study. Diversity found in both kingdoms contrasts with the limited number of crystal structures determined within each group. While the structure of almost half of mammal AQPs was resolved, only a few were resolved in plants. Strikingly, the animal structures resolved are mainly derived from the AQP2-lineage, due to their important roles in water homeostasis regulation in humans. The difference could be attributed to the approach: relevance in animal research is emphasized on pathology and in consequence drug screening that can lead to potential inhibitors, enhancers and/or regulators. By contrast, studies on plants have been mainly focused on the physiological role that AQPs play in growth, development and stress tolerance. (2) The transport capacity. Besides the well-described AQPs with high water transport capacity, large amount of evidence confirms that certain plant AQPs can carry a large list of small solutes. So far, animal AQP list is more restricted. In both kingdoms, there is a great amount of evidence on gas transport, although there is still an unsolved controversy around gas translocation as well as the role of the central pore of the tetramer. (3) More roles than expected. We found it remarkable that the view of AQPs as specific channels has evolved first toward simple transporters to molecules that can experience conformational changes triggered by biochemical and/or mechanical signals, turning them also into signaling components and/or behave as osmosensor molecules.
Collapse
Affiliation(s)
- Moira Sutka
- Departamento de Biodiversidad y Biología Experimental, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires e Instituto de Biodiversidad y Biología Experimental, Universidad de Buenos Aires y Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina
| | - Gabriela Amodeo
- Departamento de Biodiversidad y Biología Experimental, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires e Instituto de Biodiversidad y Biología Experimental, Universidad de Buenos Aires y Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina.
| | - Marcelo Ozu
- Departamento de Biodiversidad y Biología Experimental, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires e Instituto de Biodiversidad y Biología Experimental, Universidad de Buenos Aires y Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina.
| |
Collapse
|
36
|
Tight junctions of the proximal tubule and their channel proteins. Pflugers Arch 2017; 469:877-887. [DOI: 10.1007/s00424-017-2001-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Revised: 05/13/2017] [Accepted: 05/16/2017] [Indexed: 12/20/2022]
|
37
|
Alexander RT, Dimke H. Effect of diuretics on renal tubular transport of calcium and magnesium. Am J Physiol Renal Physiol 2017; 312:F998-F1015. [DOI: 10.1152/ajprenal.00032.2017] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Revised: 02/22/2017] [Accepted: 02/27/2017] [Indexed: 01/07/2023] Open
Abstract
Calcium (Ca2+) and Magnesium (Mg2+) reabsorption along the renal tubule is dependent on distinct trans- and paracellular pathways. Our understanding of the molecular machinery involved is increasing. Ca2+ and Mg2+ reclamation in kidney is dependent on a diverse array of proteins, which are important for both forming divalent cation-permeable pores and channels, but also for generating the necessary driving forces for Ca2+ and Mg2+ transport. Alterations in these molecular constituents can have profound effects on tubular Ca2+ and Mg2+ handling. Diuretics are used to treat a large range of clinical conditions, but most commonly for the management of blood pressure and fluid balance. The pharmacological targets of diuretics generally directly facilitate sodium (Na+) transport, but also indirectly affect renal Ca2+ and Mg2+ handling, i.e., by establishing a prerequisite electrochemical gradient. It is therefore not surprising that substantial alterations in divalent cation handling can be observed following diuretic treatment. The effects of diuretics on renal Ca2+ and Mg2+ handling are reviewed in the context of the present understanding of basal molecular mechanisms of Ca2+ and Mg2+ transport. Acetazolamide, osmotic diuretics, Na+/H+ exchanger (NHE3) inhibitors, and antidiabetic Na+/glucose cotransporter type 2 (SGLT) blocking compounds, target the proximal tubule, where paracellular Ca2+ transport predominates. Loop diuretics and renal outer medullary K+ (ROMK) inhibitors block thick ascending limb transport, a segment with significant paracellular Ca2+ and Mg2+ transport. Thiazides target the distal convoluted tubule; however, their effect on divalent cation transport is not limited to that segment. Finally, potassium-sparing diuretics, which inhibit electrogenic Na+ transport at distal sites, can also affect divalent cation transport.
Collapse
Affiliation(s)
- R. Todd Alexander
- Membrane Protein Disease Research Group, Department of Physiology, University of Alberta, Edmonton, Canada
- Department of Pediatrics, University of Alberta, Edmonton, Canada; and
| | - Henrik Dimke
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark
| |
Collapse
|
38
|
Caceres PS, Benedicto I, Lehmann GL, Rodriguez-Boulan EJ. Directional Fluid Transport across Organ-Blood Barriers: Physiology and Cell Biology. Cold Spring Harb Perspect Biol 2017; 9:a027847. [PMID: 28003183 PMCID: PMC5334253 DOI: 10.1101/cshperspect.a027847] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Directional fluid flow is an essential process for embryo development as well as for organ and organism homeostasis. Here, we review the diverse structure of various organ-blood barriers, the driving forces, transporters, and polarity mechanisms that regulate fluid transport across them, focusing on kidney-, eye-, and brain-blood barriers. We end by discussing how cross talk between barrier epithelial and endothelial cells, perivascular cells, and basement membrane signaling contribute to generate and maintain organ-blood barriers.
Collapse
Affiliation(s)
- Paulo S Caceres
- Margaret Dyson Vision Research Institute, Department of Ophthalmology, Weill Cornell Medical College, New York, New York 10065
| | - Ignacio Benedicto
- Margaret Dyson Vision Research Institute, Department of Ophthalmology, Weill Cornell Medical College, New York, New York 10065
| | - Guillermo L Lehmann
- Margaret Dyson Vision Research Institute, Department of Ophthalmology, Weill Cornell Medical College, New York, New York 10065
| | - Enrique J Rodriguez-Boulan
- Margaret Dyson Vision Research Institute, Department of Ophthalmology, Weill Cornell Medical College, New York, New York 10065
| |
Collapse
|
39
|
Rosenthal R, Günzel D, Krug SM, Schulzke JD, Fromm M, Yu ASL. Claudin-2-mediated cation and water transport share a common pore. Acta Physiol (Oxf) 2017; 219:521-536. [PMID: 27359349 DOI: 10.1111/apha.12742] [Citation(s) in RCA: 81] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Revised: 11/19/2015] [Accepted: 06/28/2016] [Indexed: 12/19/2022]
Abstract
AIM Claudin-2 is a tight junction protein typically located in 'leaky' epithelia exhibiting large paracellular permeabilities like small intestine and proximal kidney tubule. Former studies revealed that claudin-2 forms paracellular channels for small cations like sodium and potassium and also paracellular channels for water. This study analyses whether the diffusive transport of sodium and water occurs through a common pore of the claudin-2 channel. METHODS Wild-type claudin-2 and different claudin-2 mutants were expressed in MDCK I kidney tubule cells using an inducible system. Ion and water permeability and the effect of blocking reagents on both were investigated on different clones of the mutants. RESULTS Neutralization of a negatively charged cation interaction site in the pore with the mutation, D65N, decreased both sodium permeability and water permeability. Claudin-2 mutants (I66C and S68C) with substitution of the pore-lining amino acids with cysteine were used to test the effect of steric blocking of the claudin-2 pore by thiol-reactive reagents. Addition of thiol-reactive reagents to these mutants simultaneously decreased conductance and water permeability. Remarkably, all experimental perturbations caused parallel changes in ion conductance and water permeability, disproving different or independent passage pathways. CONCLUSION Our results indicate that claudin-2-mediated cation and water transport are frictionally coupled and share a common pore. This pore is lined and determined in permeability by amino acid residues of the first extracellular loop of claudin-2.
Collapse
Affiliation(s)
- R. Rosenthal
- Department of Gastroenterology, Infectious Diseases and Rheumatology; Institute of Clinical Physiology; Campus Benjamin Franklin; Charité - Universitätsmedizin Berlin; Berlin Germany
| | - D. Günzel
- Department of Gastroenterology, Infectious Diseases and Rheumatology; Institute of Clinical Physiology; Campus Benjamin Franklin; Charité - Universitätsmedizin Berlin; Berlin Germany
| | - S. M. Krug
- Department of Gastroenterology, Infectious Diseases and Rheumatology; Institute of Clinical Physiology; Campus Benjamin Franklin; Charité - Universitätsmedizin Berlin; Berlin Germany
| | - J.-D. Schulzke
- Department of Gastroenterology, Infectious Diseases and Rheumatology; Institute of Clinical Physiology; Campus Benjamin Franklin; Charité - Universitätsmedizin Berlin; Berlin Germany
| | - M. Fromm
- Department of Gastroenterology, Infectious Diseases and Rheumatology; Institute of Clinical Physiology; Campus Benjamin Franklin; Charité - Universitätsmedizin Berlin; Berlin Germany
| | - A. S. L. Yu
- Division of Nephrology and Hypertension, and the Kidney Institute; University of Kansas Medical Center; Kansas City KS USA
| |
Collapse
|
40
|
Muto S. Physiological roles of claudins in kidney tubule paracellular transport. Am J Physiol Renal Physiol 2017; 312:F9-F24. [DOI: 10.1152/ajprenal.00204.2016] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Revised: 10/24/2016] [Accepted: 10/25/2016] [Indexed: 12/30/2022] Open
Abstract
The paracellular pathways in renal tubular epithelia such as the proximal tubules, which reabsorb the largest fraction of filtered solutes and water and are leaky epithelia, are important routes for transepithelial transport of solutes and water. Movement occurs passively via an extracellular route through the tight junction between cells. The characteristics of paracellular transport vary among different nephron segments with leaky or tighter epithelia. Claudins expressed at tight junctions form pores and barriers for paracellular transport. Claudins are from a multigene family, comprising at least 27 members in mammals. Multiple claudins are expressed at tight junctions of individual nephron segments in a nephron segment-specific manner. Over the last decade, there have been advances in our understanding of the structure and functions of claudins. This paper is a review of our current knowledge of claudins, with special emphasis on their physiological roles in proximal tubule paracellular solute and water transport.
Collapse
Affiliation(s)
- Shigeaki Muto
- Division of Nephrology, Department of Internal Medicine, Jichi Medical University, Shimotsuke, Tochigi, Japan
| |
Collapse
|
41
|
Li Y, Wang W, Jiang T, Yang B. Aquaporins in Urinary System. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 969:131-148. [PMID: 28258571 DOI: 10.1007/978-94-024-1057-0_9] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Several aquaporin (AQP )-type water channels are expressed in kidney: AQP1 in the proximal tubule, thin descending limb of Henle, and vasa recta; AQP2 -6 in the collecting duct; AQP7 in the proximal tubule; AQP8 in the proximal tubule and collecting duct; and AQP11 in the endoplasmic reticulum of proximal tubule cells. AQP2 is the vasopressin-regulated water channel that is important in hereditary and acquired diseases affecting urine-concentrating ability. The roles of AQPs in renal physiology and transepithelial water transport have been determined using AQP knockout mouse models. This chapter describes renal physiologic insights revealed by phenotypic analysis of AQP knockout mice and the prospects for further basic and clinical studies.
Collapse
Affiliation(s)
- Yingjie Li
- Department of Pharmacology, School of Basic Medical Sciences, Peking University, Beijing, 100191, China
| | - Weiling Wang
- State Key Laboratory of Natural and Biomimetic Drugs, and Department of Pharmacology, School of Basic Medical Sciences, Peking University, Beijing, 100191, China
| | - Tao Jiang
- Department of Pharmacology, School of Basic Medical Sciences, Peking University, Beijing, 100191, China
| | - Baoxue Yang
- Department of Pharmacology, School of Basic Medical Sciences, Peking University, Beijing, 100191, China.
- State Key Laboratory of Natural and Biomimetic Drugs, Peking University, Beijing, 100191, China.
- Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, Peking University, Beijing, 100191, China.
| |
Collapse
|
42
|
Verkman AS, Tradtrantip L, Smith AJ, Yao X. Aquaporin Water Channels and Hydrocephalus. Pediatr Neurosurg 2017; 52:409-416. [PMID: 27978530 PMCID: PMC5969073 DOI: 10.1159/000452168] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Accepted: 09/21/2016] [Indexed: 01/10/2023]
Abstract
The aquaporins (AQPs) are a family of water-transporting proteins that are broadly expressed in mammalian cells. Two AQPs in the central nervous system, AQP1 and AQP4, might play a role in hydrocephalus and are thus potential drug targets. AQP1 is expressed in the ventricular-facing membrane of choroid plexus epithelial cells, where it facilitates the secretion of cerebrospinal fluid (CSF). AQP4 is expressed in astrocyte foot processes and ependymal cells lining ventricles, where it appears to facilitate the transport of excess water out of the brain. Altered expression of these AQPs in experimental animal models of hydrocephalus and limited human specimens suggests their involvement in the pathophysiology of hydrocephalus, as do data in knockout mice demonstrating a protective effect of AQP1 deletion and a deleterious effect of AQP4 deletion in hydrocephalus. Though significant questions remain, including the precise contribution of AQP1 to CSF secretion in humans and the mechanisms by which AQP4 facilitates clearance of excess brain water, AQP1 and AQP4 have been proposed as potential drug targets to reduce ventricular enlargement in hydrocephalus.
Collapse
Affiliation(s)
- Alan S Verkman
- Departments of Medicine and Physiology, University of California, San Francisco, CA, USA
| | | | | | | |
Collapse
|
43
|
Wnt5a induces renal AQP2 expression by activating calcineurin signalling pathway. Nat Commun 2016; 7:13636. [PMID: 27892464 PMCID: PMC5133730 DOI: 10.1038/ncomms13636] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Accepted: 10/20/2016] [Indexed: 12/27/2022] Open
Abstract
Heritable nephrogenic diabetes insipidus (NDI) is characterized by defective urine concentration mechanisms in the kidney, which are mainly caused by loss-of-function mutations in the vasopressin type 2 receptor. For the treatment of heritable NDI, novel strategies that bypass the defective vasopressin type 2 receptor are required to activate the aquaporin-2 (AQP2) water channel. Here we show that Wnt5a regulates AQP2 protein expression, phosphorylation and trafficking, suggesting that Wnt5a is an endogenous ligand that can regulate AQP2 without the activation of the classic vasopressin/cAMP signalling pathway. Wnt5a successfully increases the apical membrane localization of AQP2 and urine osmolality in an NDI mouse model. We also demonstrate that calcineurin is a key regulator of Wnt5a-induced AQP2 activation without affecting intracellular cAMP level and PKA activity. The importance of calcineurin is further confirmed with its activator, arachidonic acid, which shows vasopressin-like effects underlining that calcineurin activators may be potential therapeutic targets for heritable NDI.
Collapse
|
44
|
Claudins in barrier and transport function-the kidney. Pflugers Arch 2016; 469:105-113. [PMID: 27878608 DOI: 10.1007/s00424-016-1906-6] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Revised: 11/07/2016] [Accepted: 11/09/2016] [Indexed: 01/12/2023]
Abstract
Claudins are discovered to be key players in renal epithelial physiology. They are involved in developmental, physiological, and pathophysiological differentiation. In the glomerular podocytes, claudin-1 is an important determinant of cell junction fate. In the proximal tubule, claudin-2 plays important roles in paracellular salt reabsorption. In the thick ascending limb, claudin-14, -16, and -19 regulate the paracellular reabsorption of calcium and magnesium. Recessive mutations in claudin-16 or -19 cause an inherited calcium and magnesium losing disease. Synonymous variants in claudin-14 have been associated with hypercalciuric nephrolithiasis by genome-wide association studies (GWASs). More importantly, claudin-14 gene expression can be regulated by extracellular calcium levels via the calcium sensing receptor. In the distal tubules, claudin-4 and -8 form paracellular chloride pathway to facilitate electrogenic sodium reabsorption. Aldosterone, WNK4, Cap1, and KLHL3 are powerful regulators of claudin and the paracellular chloride permeability. The lessons learned on claudins from the kidney will have a broader impact on tight junction biology in other epithelia and endothelia.
Collapse
|
45
|
Yu L, Rodriguez RA, Chen LL, Chen LY, Perry G, McHardy SF, Yeh CK. 1,3-propanediol binds deep inside the channel to inhibit water permeation through aquaporins. Protein Sci 2016; 25:433-41. [PMID: 26481430 DOI: 10.1002/pro.2832] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2015] [Revised: 10/15/2015] [Accepted: 10/16/2015] [Indexed: 01/10/2023]
Abstract
Aquaporins and aquaglyceroporins (AQPs) are membrane channel proteins responsible for transport of water and for transport of glycerol in addition to water across the cell membrane, respectively. They are expressed throughout the human body and also in other forms of life. Inhibitors of human AQPs have been sought for therapeutic treatment for various medical conditions including hypertension, refractory edema, neurotoxic brain edema, and so forth. Conducting all-atom molecular dynamics simulations, we computed the binding affinity of acetazolamide to human AQP4 that agrees closely with in vitro experiments. Using this validated computational method, we found that 1,3-propanediol (PDO) binds deep inside the AQP4 channel to inhibit that particular aquaporin efficaciously. Furthermore, we used the same method to compute the affinities of PDO binding to four other AQPs and one aquaglyceroporin whose atomic coordinates are available from the protein data bank (PDB). For bovine AQP1, human AQP2, AQP4, AQP5, and Plasmodium falciparum PfAQP whose structures were resolved with high resolution, we obtained definitive predictions on the PDO dissociation constant. For human AQP1 whose PDB coordinates are less accurate, we estimated the dissociation constant with a rather large error bar. Taking into account the fact that PDO is generally recognized as safe by the US FDA, we predict that PDO can be an effective diuretic which directly modulates water flow through the protein channels. It should be free from the serious side effects associated with other diuretics that change the hydro-homeostasis indirectly by altering the osmotic gradients.
Collapse
Affiliation(s)
- Lili Yu
- Department of Physics, University of Texas at San Antonio, San Antonio, Texas, 78249
| | - Roberto A Rodriguez
- Department of Physics, University of Texas at San Antonio, San Antonio, Texas, 78249
| | - L Laurie Chen
- Medical School, University of Texas Southwestern Medical Center, Dallas, Texas, 75390
| | - Liao Y Chen
- Department of Physics, University of Texas at San Antonio, San Antonio, Texas, 78249
| | - George Perry
- Department of Biology, University of Texas at San Antonio, San Antonio, Texas, 78249
| | - Stanton F McHardy
- Department of Chemistry, University of Texas at San Antonio, San Antonio, Texas, 78249
| | - Chih-Ko Yeh
- Department of Comprehensive Dentistry, University of Texas Health Science Center at San Antonio & GRECC, South Texas Veterans Health Care System, San Antonio, Texas 78229
| |
Collapse
|
46
|
Chang SY, Lo CS, Zhao XP, Liao MC, Chenier I, Bouley R, Ingelfinger JR, Chan JS, Zhang SL. Overexpression of angiotensinogen downregulates aquaporin 1 expression via modulation of Nrf2-HO-1 pathway in renal proximal tubular cells of transgenic mice. J Renin Angiotensin Aldosterone Syst 2016; 17:17/3/1470320316668737. [PMID: 27638854 PMCID: PMC5843896 DOI: 10.1177/1470320316668737] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Accepted: 08/05/2016] [Indexed: 12/14/2022] Open
Abstract
Introduction: We aimed to examine the regulation of aquaporin 1 expression in an angiotensinogen transgenic mouse model, focusing on underlying mechanisms. Methods: Male transgenic mice overexpressing rat angiotensinogen in their renal proximal tubular cells (RPTCs) and rat immortalised RPTCs stably transfected with rat angiotensinogen cDNA were used. Results: Angiotensinogen-transgenic mice developed hypertension and nephropathy, changes that were either partially or completely attenuated by treatment with losartan or dual renin–angiotensin system blockade (losartan and perindopril), respectively, while hydralazine prevented hypertension but not nephropathy. Decreased expression of aquaporin 1 and heme oxygenase-1 and increased expression of nuclear factor erythroid 2-related factor 2 (Nrf2) and sodium–hydrogen exchanger 3 were observed in RPTCs of angiotensinogen-transgenic mice and in angiotensinogen-transfected immortalised RPTCs. These parameters were normalised by dual renin–angiotensin system blockade. Both in vivo and in vitro studies identified a novel mechanism in which angiotensinogen overexpression in RPTCs enhances the cytosolic accumulation of Nrf2 via the phosphorylation of pGSK3β Y216. Consequently, lower intranuclear Nrf2 levels are less efficient to trigger heme oxygenase-1 expression as a defence mechanism, which subsequently diminishes aquaporin 1 expression in RPTCs. Conclusions: Angiotensinogen-mediated downregulation of aquaporin 1 and Nrf2 signalling may play an important role in intrarenal renin–angiotensin system-induced hypertension and kidney injury.
Collapse
Affiliation(s)
- Shiao-Ying Chang
- Centre de Recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), Canada
| | - Chao-Sheng Lo
- Centre de Recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), Canada
| | - Xin-Ping Zhao
- Centre de Recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), Canada
| | - Min-Chun Liao
- Centre de Recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), Canada
| | - Isabelle Chenier
- Centre de Recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), Canada
| | - Richard Bouley
- Division of Nephology, Massachusetts General Hospital and Harvard Medical School, USA
| | - Julie R Ingelfinger
- Pediatric Nephrology Unit, Massachusetts General Hospital and Harvard Medical School, USA
| | - John Sd Chan
- Centre de Recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), Canada
| | - Shao-Ling Zhang
- Centre de Recherche du Centre Hospitalier de l'Université de Montréal (CRCHUM), Canada
| |
Collapse
|
47
|
Tradtrantip L, Verkman AS. Aquaporin gene therapy for disorders of cholestasis? Hepatology 2016; 64:344-6. [PMID: 27115396 PMCID: PMC5687515 DOI: 10.1002/hep.28623] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Accepted: 04/20/2016] [Indexed: 12/07/2022]
Affiliation(s)
- Lukmanee Tradtrantip
- Departments of Medicine and Physiology, University of California San Francisco, San Francisco, CA
| | - Alan S Verkman
- Departments of Medicine and Physiology, University of California San Francisco, San Francisco, CA
| |
Collapse
|
48
|
Arrighi S, Bosi G, Accogli G, Desantis S. Seasonal and Ageing-Depending Changes of Aquaporins 1 and 9 Expression in the Genital Tract of Buffalo Bulls (Bubalus bubalis). Reprod Domest Anim 2016; 51:515-23. [DOI: 10.1111/rda.12713] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Accepted: 05/03/2016] [Indexed: 01/19/2023]
Affiliation(s)
- S. Arrighi
- Department of Health, Animal Science and Food Safety (VESPA); Laboratory of Anatomy; Università degli Studi di Milano; Milano Italy
| | - G. Bosi
- Department of Health, Animal Science and Food Safety (VESPA); Laboratory of Anatomy; Università degli Studi di Milano; Milano Italy
| | - G. Accogli
- Department of Emergency and Organ Transplantation (DETO); Veterinary Clinics and Animal Productions Section; University of Bari “Aldo Moro”; Bari Italy
| | - S. Desantis
- Department of Emergency and Organ Transplantation (DETO); Veterinary Clinics and Animal Productions Section; University of Bari “Aldo Moro”; Bari Italy
| |
Collapse
|
49
|
Al-Samir S, Wang Y, Meissner JD, Gros G, Endeward V. Cardiac Morphology and Function, and Blood Gas Transport in Aquaporin-1 Knockout Mice. Front Physiol 2016; 7:181. [PMID: 27252655 PMCID: PMC4878313 DOI: 10.3389/fphys.2016.00181] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2016] [Accepted: 05/06/2016] [Indexed: 12/24/2022] Open
Abstract
We have studied cardiac and respiratory functions of aquaporin-1-deficient mice by the Pressure-Volume-loop technique and by blood gas analysis. In addition, the morphological properties of the animals' hearts were analyzed. In anesthesia under maximal dobutamine stimulation, the mice exhibit a moderately elevated heart rate of < 600 min−1 and an O2 consumption of ~0.6 ml/min/g, which is about twice the basal rate. In this state, which is similar to the resting state of the conscious animal, all cardiac functions including stroke volume and cardiac output exhibited resting values and were identical between deficient and wildtype animals. Likewise, pulmonary and peripheral exchange of O2 and CO2 were normal. In contrast, several morphological parameters of the heart tissue of deficient mice were altered: (1) left ventricular wall thickness was reduced by 12%, (2) left ventricular mass, normalized to tibia length, was reduced by 10–20%, (3) cardiac muscle fiber cross sectional area was decreased by 17%, and (4) capillary density was diminished by 10%. As the P-V-loop technique yielded normal end-diastolic and end-systolic left ventricular volumes, the deficient hearts are characterized by thin ventricular walls in combination with normal intraventricular volumes. The aquaporin-1-deficient heart thus seems to be at a disadvantage compared to the wild-type heart by a reduced left-ventricular wall thickness and an increased diffusion distance between blood capillaries and muscle mitochondria. While under the present quasi-resting conditions these morphological alterations have no consequences for cardiac function, we expect that the deficient hearts will show a reduced maximal cardiac output.
Collapse
Affiliation(s)
- Samer Al-Samir
- Abteilung Molekular- und Zellphysiologie, AG Vegetative Physiologie 4220, Medizinische Hochschule Hannover Hannover, Germany
| | - Yong Wang
- Division Molecular and Translational Cardiology, Department Cardiology and Angiology, Medizinische Hochschule Hannover Hannover, Germany
| | - Joachim D Meissner
- Abteilung Molekular- und Zellphysiologie, AG Vegetative Physiologie 4220, Medizinische Hochschule Hannover Hannover, Germany
| | - Gerolf Gros
- Abteilung Molekular- und Zellphysiologie, AG Vegetative Physiologie 4220, Medizinische Hochschule Hannover Hannover, Germany
| | - Volker Endeward
- Abteilung Molekular- und Zellphysiologie, AG Vegetative Physiologie 4220, Medizinische Hochschule Hannover Hannover, Germany
| |
Collapse
|
50
|
Browne JA, Yang R, Eggener SE, Leir SH, Harris A. HNF1 regulates critical processes in the human epididymis epithelium. Mol Cell Endocrinol 2016; 425:94-102. [PMID: 26808453 PMCID: PMC4799753 DOI: 10.1016/j.mce.2016.01.021] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Revised: 12/26/2015] [Accepted: 01/20/2016] [Indexed: 01/22/2023]
Abstract
The luminal environment of the epididymis participates in sperm maturation and impacts male fertility. It is dependent on the coordinated expression of many genes encoding proteins with a role in epithelial transport. We identified cis-regulatory elements for critical genes in epididymis function, by mapping open chromatin genome-wide in human epididymis epithelial (HEE) cells. Bioinformatic predictions of transcription factors binding to the regulatory elements suggested an important role for hepatocyte nuclear factor 1 (HNF1) in the transcriptional program of these cells. Chromatin immunoprecipitation and deep sequencing (ChIP-seq) revealed HNF1 target genes in HEE cells. In parallel, the contribution of HNF1 to the transcriptome of HEE cells was determined by RNA-seq, following siRNA-mediated depletion of both HNF1α and HNF1β transcription factors. Repression of these factors caused differential expression of 1892 transcripts (902 were downregulated and 990 upregulated) in comparison to non-targeting siRNAs. Differentially expressed genes with HNF1 ChIP-seq peaks within 20 kb were subject to gene ontology process enrichment analysis. Among the most significant processes associated with down-regulated genes were epithelial transport of water, phosphate and bicarbonate, all critical processes in epididymis epithelial function. Measurements of intracellular pH (pHi) confirmed a role for HNF1 in regulating the epididymis luminal environment.
Collapse
Affiliation(s)
- James A Browne
- Human Molecular Genetics Program, Lurie Children's Research Center, Chicago, IL, USA
| | - Rui Yang
- Human Molecular Genetics Program, Lurie Children's Research Center, Chicago, IL, USA
| | - Scott E Eggener
- Department of Pediatrics, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Shih-Hsing Leir
- Human Molecular Genetics Program, Lurie Children's Research Center, Chicago, IL, USA
| | - Ann Harris
- Human Molecular Genetics Program, Lurie Children's Research Center, Chicago, IL, USA.
| |
Collapse
|