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Acute regulated expression of pendrin in human urinary exosomes. Pflugers Arch 2017; 470:427-438. [PMID: 28803436 DOI: 10.1007/s00424-017-2049-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Revised: 07/23/2017] [Accepted: 07/26/2017] [Indexed: 10/19/2022]
Abstract
It is well known that pendrin, an apical Cl-/HCO3-exchanger in type B intercalated cells, is modulated by chronic acid-base disturbances and electrolyte intake. To study this adaptation further at the acute level, we analyzed urinary exosomes from individuals subjected to oral acute acid, alkali, and NaCl loading. Acute oral NH4Cl loading (n = 8) elicited systemic acidemia with a drop in urinary pH and an increase in urinary NH4 excretion. Nadir urinary pH was achieved 5 h after NH4Cl loading. Exosomal pendrin abundance was dramatically decreased at 3 h after acid loading. In contrast, after acute equimolar oral NaHCO3 loading (n = 8), urinary and venous blood pH rose rapidly with a significant attenuation of urinary NH4 excretion. Alkali loading caused rapid upregulation of exosomal pendrin abundance at 1 h and normalized within 3 h of treatment. Equimolar NaCl loading (n = 6) did not alter urinary or venous blood pH or urinary NH4 excretion. However, pendrin abundance in urinary exosomes was significantly reduced at 2 h of NaCl ingestion with lowest levels observed at 4 h after treatment. In patients with inherited distal renal tubular acidosis (dRTA), pendrin abundance in urinary exosomes was greatly reduced and did not change upon oral NH4Cl loading. In summary, pendrin can be detected and quantified in human urinary exosomes by immunoblotting. Acid, alkali, and NaCl loadings cause acute changes in pendrin abundance in urinary exosomes within a few hours. Our data suggest that exosomal pendrin is a promising urinary biomarker for acute acid-base and volume status changes in humans.
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Burnstock G, Loesch A. Sympathetic innervation of the kidney in health and disease: Emphasis on the role of purinergic cotransmission. Auton Neurosci 2017; 204:4-16. [DOI: 10.1016/j.autneu.2016.05.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Revised: 05/27/2016] [Accepted: 05/29/2016] [Indexed: 11/29/2022]
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Abstract
The H(+) concentration in human blood is kept within very narrow limits, ~40 nmol/L, despite the fact that dietary metabolism generates acid and base loads that are added to the systemic circulation throughout the life of mammals. One of the primary functions of the kidney is to maintain the constancy of systemic acid-base chemistry. The kidney has evolved the capacity to regulate blood acidity by performing three key functions: (i) reabsorb HCO3(-) that is filtered through the glomeruli to prevent its excretion in the urine; (ii) generate a sufficient quantity of new HCO3(-) to compensate for the loss of HCO3(-) resulting from dietary metabolic H(+) loads and loss of HCO3(-) in the urea cycle; and (iii) excrete HCO3(-) (or metabolizable organic anions) following a systemic base load. The ability of the kidney to perform these functions requires that various cell types throughout the nephron respond to changes in acid-base chemistry by modulating specific ion transport and/or metabolic processes in a coordinated fashion such that the urine and renal vein chemistry is altered appropriately. The purpose of the article is to provide the interested reader with a broad review of a field that began historically ~60 years ago with whole animal studies, and has evolved to where we are currently addressing questions related to kidney acid-base regulation at the single protein structure/function level.
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Affiliation(s)
- Ira Kurtz
- Division of Nephrology, David Geffen School of Medicine, Los Angeles, CA; Brain Research Institute, UCLA, Los Angeles, CA
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Sun X, Stephens L, DuBose TD, Petrovic S. Adaptation by the collecting duct to an exogenous acid load is blunted by deletion of the proton-sensing receptor GPR4. Am J Physiol Renal Physiol 2015; 309:F120-36. [DOI: 10.1152/ajprenal.00507.2014] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Accepted: 05/05/2015] [Indexed: 12/14/2022] Open
Abstract
We previously reported that the deletion of the pH sensor GPR4 causes a non-gap metabolic acidosis and defective net acid excretion (NAE) in the GPR4 knockout mouse (GPR4−/−) (Sun X, Yang LV, Tiegs BC, Arend LJ, McGraw DW, Penn RB, and Petrovic S. J Am Soc Nephrol 21: 1745–1755, 2010). Since the major regulatory site of NAE in the kidney is the collecting duct (CD), we examined acid-base transport proteins in intercalated cells (ICs) of the CD and found comparable mRNA expression of kidney anion exchanger 1 (kAE1), pendrin, and the a4 subunit of H+-ATPase in GPR4−/− vs. +/+. However, NH4Cl loading elicited adaptive doubling of AE1 mRNA in GPR4+/+, but a 50% less pronounced response in GPR4−/−. In GPR4+/+, NH4Cl loading evoked a cellular response characterized by an increase in AE1-labeled and a decrease in pendrin-labeled ICs similar to what was reported in rabbits and rats. This response did not occur in GPR4−/−. Microperfusion experiments demonstrated that the activity of the basolateral Cl−/HCO3− exchanger, kAE1, in CDs isolated from GPR4−/− failed to increase with NH4Cl loading, in contrast to the increase observed in GPR4+/+. Therefore, the deficiency of GPR4 blunted, but did not eliminate the adaptive response to an acid load, suggesting a compensatory response from other pH/CO2/bicarbonate sensors. Indeed, the expression of the calcium-sensing receptor (CaSR) was nearly doubled in GPR4−/− kidneys, in the absence of apparent disturbances of Ca2+ homeostasis. In summary, the expression and activity of the key transport proteins in GPR4−/− mice are consistent with spontaneous metabolic acidosis, but the adaptive response to a superimposed exogenous acid load is blunted and might be partially compensated for by CaSR.
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Affiliation(s)
- Xuming Sun
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, North Carolina
| | - Lisa Stephens
- Department of Internal Medicine, University of Cincinnati, Cincinnati, Ohio
| | - Thomas D. DuBose
- Section on Nephrology, Department of Internal Medicine, Wake Forest School of Medicine, Winston-Salem, North Carolina
| | - Snezana Petrovic
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, North Carolina
- Section on Nephrology, Department of Internal Medicine, Wake Forest School of Medicine, Winston-Salem, North Carolina
- Claude D. Pepper Older Americans Independence Center, Wake Forest School of Medicine, Winston-Salem, North Carolina
- Hypertension and Vascular Research Center, Wake Forest School of Medicine, Winston-Salem, North Carolina; and
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Schwartz GJ, Al-Awqati Q. Role of hensin in mediating the adaptation of the cortical collecting duct to metabolic acidosis. Curr Opin Nephrol Hypertens 2005; 14:383-8. [PMID: 15931009 DOI: 10.1097/01.mnh.0000172727.82993.aa] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
PURPOSE OF REVIEW The cortical collecting duct is able to secrete HCO3-, a state that can be converted to acid secretion during metabolic acidosis. Bicarbonate secretion in this segment is mediated by beta-intercalated cells whereas alpha-intercalated cells perform acid secretion. During metabolic acidosis, the number of beta-intercalated cells is reduced while that of alpha-intercalated cells increases without a change in the total number of intercalated cells, suggesting conversion of one cell type to another. Using an immortalized intercalated cell line we found that this adaptation is mediated by an extracellular protein named hensin. Hensin is secreted as a monomer which is then polymerized in the extracellular environment by a complex process requiring at least three other proteins. RECENT FINDINGS We describe that a cyclophilin, via its cis/trans prolyl isomerase activity, is required for this polymerization. This may explain the distal renal tubular acidosis observed with cyclosporin A therapy. In addition, galectin-3 is needed to aggregate the protein. Finally, we recently found that activation of integrins is also necessary for the development of the hensin fiber. Hensin is expressed in all epithelia and deletion of its gene is embryonic lethal at an early stage when the first columnar epithelia develop. SUMMARY These studies suggest that the response of intercalated cells to metabolic acidosis uses a pathway that is involved in terminal differentiation of columnar epithelia.
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Affiliation(s)
- George J Schwartz
- Departments of Pediatrics and Medicine, University of Rochester School of Medicine, Rochester, New York 14642, USA.
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Kim YH, Kim J, Verkman AS, Madsen KM. Increased expression of H+-ATPase in inner medullary collecting duct of aquaporin-1-deficient mice. Am J Physiol Renal Physiol 2003; 285:F550-7. [PMID: 12759225 DOI: 10.1152/ajprenal.00029.2003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Phenotype analysis has demonstrated that aquaporin-1 (AQP1) null mice are polyuric and manifest a urinary concentrating defect because of an inability to create a hypertonic medullary interstitium. We report here that deletion of AQP1 is also associated with a decrease in urinary pH from 6.15 +/- (SE) 0.1 to 5.63 +/- 0.07. To explore the mechanism of the decrease in urinary pH, we examined the expression of H+-ATPase in kidneys of AQP1 null mice. There was strong labeling for H+-ATPase in intercalated cells and proximal tubule cells in both AQP1 null and wild-type mice. Strong H+-ATPase immunostaining was also present in the apical plasma membrane of inner medullary collecting duct (IMCD) cells in AQP1 null mice, whereas no H+-ATPase labeling was observed in IMCD cells in wild-type mice. In addition, there was an increase in the prevalence of type A intercalated cells in the IMCD of AQP1 null mice, suggesting that the deletion of intercalated cells from the IMCD, which normally occurs during postnatal kidney development, was impaired. Western blot analysis of H+-ATPase expression in the different regions of the kidney demonstrated a significant increase in H+-ATPase protein in the inner medulla of AQP1 null mice compared with wild-type mice. There were no changes in H+-ATPase expression in the cortex or outer medulla. These results represent the first demonstration of apical H+-ATPase immunoreactivity in IMCD cells in vivo and suggest that the decrease in urinary pH observed in AQP1 null mice is due to upregulation of H+-ATPase in the IMCD. The induction of H+-ATPase expression in IMCD cells of AQP1 null mice may be related to the chronically low interstitial osmolality in these animals. The challenge will be to identify the molecular signal(s) responsible for the de novo H+-ATPase expression.
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Affiliation(s)
- Young-Hee Kim
- Dept. of Medicine, Univ. of Florida, Gainesville, FL 32610-0215, USA
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Chen S, Agarwal A, Glushakova OY, Jorgensen MS, Salgar SK, Poirier A, Flotte TR, Croker BP, Madsen KM, Atkinson MA, Hauswirth WW, Berns KI, Tisher CC. Gene delivery in renal tubular epithelial cells using recombinant adeno-associated viral vectors. J Am Soc Nephrol 2003; 14:947-58. [PMID: 12660329 DOI: 10.1097/01.asn.0000057858.45649.f7] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Gene therapy has the potential to provide a therapeutic strategy for numerous renal diseases such as diabetic nephropathy, chronic rejection, Alport syndrome, polycystic kidney disease, and inherited tubular disorders. In previous studies using cationic liposomes or adenoviral or retroviral vectors to deliver genes into the kidney, transgene expression has been transient and often associated with adverse host immune responses, particularly with the use of adenoviral vectors. The unique properties of recombinant adeno-associated viral (rAAV) vectors permit long-term stable transgene expression with a relatively low host immune response. The purpose of the present study was to evaluate gene expression in the rat kidney after intrarenal arterial infusion of a rAAV (serotype 2) vector encoding green fluorescence protein (GFP) induced by a cytomegalovirus-chicken beta-actin hybrid promoter. The left kidney of experimental animals was treated with either saline or transduced with rAAV2-GFP (0.125 ml/100 g body wt, 1 x 10(10)/ml infectious units) through the renal artery. A time-dependent expression of GFP was observed in all kidneys injected with rAAV2-GFP, with maximal expression observed at 6 wk posttransduction. The expression of GFP was restricted to cells in the S(3) segment of the proximal tubule and intercalated cells in the collecting duct, the latter identified by co-localization with H(+)-ATPase. No transduction was observed in the glomeruli or the intrarenal vasculature. These studies demonstrate successful transgene expression in tubular epithelial cells, specifically in the S(3) segment of the proximal tubule and intercalated cells, after intrarenal administration of a rAAV vector and provide the impetus for further studies to exploit its use as a tool for gene therapy in the kidney.
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Affiliation(s)
- Sifeng Chen
- Department of Medicine, University of Florida, Gainesville, Florida 32610, USA
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Kim YH, Kwon TH, Frische S, Kim J, Tisher CC, Madsen KM, Nielsen S. Immunocytochemical localization of pendrin in intercalated cell subtypes in rat and mouse kidney. Am J Physiol Renal Physiol 2002; 283:F744-54. [PMID: 12217866 DOI: 10.1152/ajprenal.00037.2002] [Citation(s) in RCA: 138] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Recent studies have demonstrated that a novel anion exchanger, pendrin, is expressed in the apical domain of type B intercalated cells in the mammalian collecting duct. The purpose of this study was 1) to determine the expression and distribution of pendrin along the collecting duct and connecting tubule of mouse and rat kidney and establish whether pendrin is expressed in the non-A-non-B intercalated cells and 2) to determine the intracellular localization of pendrin in the different populations of intercalated cells by immunoelectron microscopy. A peptide-derived affinity-purified antibody was generated that specifically recognized pendrin in immunoblots of rat and mouse kidney. Immunohistochemistry and confocal laser scanning microscopy demonstrated the presence of pendrin in apical domains of all type B intercalated cells in mouse and rat connecting tubule and collecting duct. In addition, strong pendrin immunostaining was observed in non-A-non-B intercalated cells. There was no labeling of type A intercalated cells. Immunoelectron microscopy demonstrated that pendrin was located in the apical plasma membrane and intracellular vesicles of both type B intercalated cells and non-A-non-B cells; the latter was identified by the presence of H(+)-ATPase in the apical plasma membrane. The results of this study demonstrate that both pendrin and H(+)-ATPase are expressed in the apical plasma membrane of non-A-non-B intercalated cells, suggesting that these cells are capable of both HCO and proton secretion. Furthermore, the presence of pendrin in both the apical plasma membrane and the apical intracellular vesicles of type B and non-A-non-B intercalated cells suggests that HCO secretion may be regulated by trafficking of pendrin between the two membrane compartments.
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MESH Headings
- Amino Acid Sequence
- Animals
- Blotting, Western
- Carrier Proteins/biosynthesis
- Carrier Proteins/genetics
- Cells, Cultured
- Electrophoresis, Polyacrylamide Gel
- Immunohistochemistry
- Kidney/cytology
- Kidney/metabolism
- Kidney/ultrastructure
- Kidney Tubules, Collecting/cytology
- Kidney Tubules, Collecting/metabolism
- Male
- Membrane Proteins/biosynthesis
- Membrane Proteins/chemistry
- Membrane Transport Proteins
- Mice
- Mice, Inbred C57BL
- Microscopy, Confocal
- Microscopy, Immunoelectron
- Molecular Sequence Data
- Proton-Translocating ATPases/metabolism
- Rats
- Rats, Sprague-Dawley
- Rats, Wistar
- Subcellular Fractions/metabolism
- Sulfate Transporters
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Affiliation(s)
- Young-Hee Kim
- Department of Medicine, Hypertension and Transplantation, University of Florida, Gainesville 32610, USA
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Kwon TH, Fulton C, Wang W, Kurtz I, Frøkiaer J, Aalkjaer C, Nielsen S. Chronic metabolic acidosis upregulates rat kidney Na-HCO cotransporters NBCn1 and NBC3 but not NBC1. Am J Physiol Renal Physiol 2002; 282:F341-51. [PMID: 11788449 DOI: 10.1152/ajprenal.00104.2001] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Several members of the Na-HCO cotransporter (NBC) family have recently been identified functionally and partly characterized, including rkNBC1, NBCn1, and NBC3. Regulation of these NBCs may play a role in the maintenance of intracellular pH and in the regulation of renal acid-base balance. However, it is unknown whether the expressions of these NBCs are regulated in response to changes in acid-base status. We therefore tested whether chronic metabolic acidosis (CMA) affects the abundance of these NBCs in kidneys using two conventional protocols. In protocol 1, rats were treated with NH(4)Cl in their drinking water (12 +/- 1 mmol. rat(-1). day(-1)) for 2 wk with free access to water (n = 8). Semiquantitative immunoblotting demonstrated that whole kidney abundance of NBCn1 and NBC3 in rats with CMA was dramatically increased to 995 +/- 87 and 224 +/- 35%, respectively, of control levels (P < 0.05), whereas whole kidney rkNBC1 was unchanged (88 +/- 14%). In protocol 2, rats were given NH(4)Cl in their food (10 +/- 1 mmol. rat(-1). day(-1)) for 7 days, with a fixed daily water intake (n = 6). Consistent with protocol 1, whole kidney abundances of NBCn1 (262 +/- 42%) and NBC3 (160 +/- 31%) were significantly increased compared with controls (n = 6), whereas whole kidney rkNBC1 was unchanged (84 +/- 17%). In both protocols, immunocytochemistry confirmed upregulation of NBCn1 and NBC3 with no change in the segmental distribution along the nephron. Consistent with the increase in NBCn1, measurements of pH transients in medullary thick ascending limb (mTAL) cells in kidney slices revealed two- to threefold increases in DIDS- sensitive, Na(+)-dependent HCO uptake in rats with CMA. In conclusion, CMA is associated with a marked increase in the abundance of NBCn1 in the mTAL and NBC3 in intercalated cells, whereas the abundance of NBC1 in the proximal tubule was not altered. The increased abundance of NBCn1 may play a role in the reabsorption of NH in the mTAL and increased NBC3 in reabsorbing HCO.
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Affiliation(s)
- Tae-Hwan Kwon
- The Water and Salt Research Center, University of Aarhus, DK-8000 Aarhus C, Denmark
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Schwartz GJ, Tsuruoka S, Vijayakumar S, Petrovic S, Mian A, Al-Awqati Q. Acid incubation reverses the polarity of intercalated cell transporters, an effect mediated by hensin. J Clin Invest 2002; 109:89-99. [PMID: 11781354 PMCID: PMC150817 DOI: 10.1172/jci13292] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Metabolic acidosis causes a reversal of polarity of HCO(3)(-) flux in the cortical collecting duct (CCD). In CCDs incubated in vitro in acid media, beta-intercalated (HCO(3)(-)-secreting) cells are remodeled to functionally resemble alpha-intercalated (H(+)-secreting) cells. A similar remodeling of beta-intercalated cells, in which the polarity of H(+) pumps and Cl(-)/HCO(3)(-) exchangers is reversed, occurs in cell culture and requires the deposition of polymerized hensin in the ECM. CCDs maintained 3 h at low pH ex vivo display a reversal of HCO(3)(-) flux that is quantitatively similar to an effect previously observed in acid-treated rabbits in vivo. We followed intracellular pH in the same beta-intercalated cells before and after acid incubation and found that apical Cl/HCO(3) exchange was abolished following acid incubation. Some cells also developed basolateral Cl(-)/HCO(3)(-) exchange, indicating a reversal of intercalated cell polarity. This adaptation required intact microtubules and microfilaments, as well as new protein synthesis, and was associated with decreased size of the apical surface of beta-intercalated cells. Addition of anti-hensin antibodies prevented the acid-induced changes in apical and basolateral Cl(-)/HCO(3)(-) exchange observed in the same cells and the corresponding suppression of HCO(3)(-) secretion. Acid loading also promoted hensin deposition in the ECM underneath adapting beta-intercalated cells. Hence, the adaptive conversion of beta-intercalated cells to alpha-intercalated cells during acid incubation depends upon ECM-associated hensin.
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Affiliation(s)
- George J Schwartz
- Department of Pediatrics and Strong Children's Research Center, University of Rochester School of Medicine, Rochester, New York 14642, USA.
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Schwartz GJ, Tsuruoka S, Vijayakumar S, Petrovic S, Mian A, Al-Awqati Q. Acid incubation reverses the polarity of intercalated cell transporters, an effect mediated by hensin. J Clin Invest 2002. [DOI: 10.1172/jci0213292] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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12
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Verlander JW, Moudy RM, Campbell WG, Cain BD, Wingo CS. Immunohistochemical localization of H-K-ATPase alpha(2c)-subunit in rabbit kidney. Am J Physiol Renal Physiol 2001; 281:F357-65. [PMID: 11457728 DOI: 10.1152/ajprenal.2001.281.2.f357] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The rabbit kidney possesses mRNA for the H-K-ATPase alpha(1)-subunit (HKalpha(1)) and two splice variants of the H-K-ATPase alpha(2)-subunit (HKalpha(2)). The purpose of this study was to determine the specific distribution of one of these, the H-K-ATPase alpha(2c)-subunit isoform (HKalpha(2c)), in rabbit kidney by immunohistochemistry. Chicken polyclonal antibodies against a peptide based on the NH(2) terminus of HKalpha(2c) were used to detect HKalpha(2c) immunoreactivity in tissue sections. Immunohistochemical localization of HKalpha(2c) revealed intense apical immunoreactivity in a subpopulation of cells in the connecting segment, cortical collecting duct, and outer medullary collecting duct in both the outer and inner stripe. An additional population of cells exhibited a thin apical band of immunolabel. Immunohistochemical colocalization of HKalpha(2c) with carbonic anhydrase II, the Cl(-)/HCO exchanger AE1, and HKalpha(1) indicated that both type A and type B intercalated cells possessed intense apical HKalpha(2c) immunoreactivity, whereas principal cells and connecting segment cells had only a thin apical band of HKalpha(2c). Labeled cells were evident through the middle third of the inner medullary collecting duct in the majority of animals. Immunolabel was also present in papillary surface epithelial cells, cells in the cortical thick ascending limb of Henle's loop (cTAL), and the macula densa. Thus in the rabbit kidney, apical HKalpha(2c) is present and may contribute to acid secretion or potassium uptake throughout the connecting segment and collecting duct in both type A and type B intercalated cells, principal cells, and connecting segment cells, as well as in cells in papillary surface epithelium, cTAL, and macula densa.
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Affiliation(s)
- J W Verlander
- Nephrology and Hypertension, Department of Veterans Affairs Medical Center, Gainesville, Florida 32608-1197, USA
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Pushkin A, Yip KP, Clark I, Abuladze N, Kwon TH, Tsuruoka S, Schwartz GJ, Nielsen S, Kurtz I. NBC3 expression in rabbit collecting duct: colocalization with vacuolar H+-ATPase. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 277:F974-81. [PMID: 10600945 DOI: 10.1152/ajprenal.1999.277.6.f974] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We have recently cloned and characterized a unique sodium bicarbonate cotransporter, NBC3, which unlike other members of the NBC family, is ethylisopropylamiloride (EIPA) inhibitable, DIDS insensitive, and electroneutral (A. Pushkin, N. Abuladze, I. Lee, D. Newman, J. Hwang, and I. Kurtz. J. Biol. Chem. 274: 16569-16575, 1999). In the present study, a specific polyclonal antipeptide COOH-terminal antibody, NBC3-C1, was generated and used to determine the pattern of NBC3 protein expression in rabbit kidney. A major band of approximately 200 kDa was detected on immunoblots of rabbit kidney. Immunocytochemistry of rabbit kidney frozen sections revealed specific staining of the apical membrane of intercalated cells in both the cortical and outer medullary collecting ducts. The pattern of NBC3 protein expression in the collecting duct was nearly identical to the same sections stained with an antibody against the vacuolar H+-ATPase 31-kDa subunit. In addition, the NBC3-C1 antibody coimmunoprecipitated the vacuolar H+-ATPase 31-kDa subunit. Functional studies in outer medullary collecting ducts (inner stripe) showed that type A intercalated cells have an apical Na+-dependent base transporter that is EIPA inhibitable and DIDS insensitive. The data suggest that NBC3 participates in H+/base transport in the collecting duct. The close association of NBC3 and the vacuolar H+-ATPase in type A intercalated cells suggests a potential structural/functional interaction between the two transporters.
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Affiliation(s)
- A Pushkin
- Division of Nephrology, University of California at Los Angeles, School of Medicine, Los Angeles, California 90095, USA
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Kim J, Kim YH, Cha JH, Tisher CC, Madsen KM. Intercalated cell subtypes in connecting tubule and cortical collecting duct of rat and mouse. J Am Soc Nephrol 1999; 10:1-12. [PMID: 9890303 DOI: 10.1681/asn.v1011] [Citation(s) in RCA: 123] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
At least two populations of intercalated cells, type A and type B, exist in the connecting tubule (CNT), initial collecting tubule (ICT), and cortical collecting duct (CCD). Type A intercalated cells secrete protons via an apical H+-ATPase and reabsorb bicarbonate by a band 3-like Cl-/HCO3-exchanger, AE1, located in the basolateral plasma membrane. Type B intercalated cells secrete bicarbonate by an apical Cl-/HCO3- exchanger that is distinct from AE1 and remains to be identified. They express H+-ATPase in the basolateral plasma membrane and in vesicles throughout the cytoplasm. A third type of intercalated cell with apical H+-ATPase, but no AE1, has been described in the CNT and CCD of both rat and mouse. The prevalence of the third cell type is not known. The aim of this study was to characterize and quantify intercalated cell subtypes, including the newly described third non A-non B cell, in the CNT, ICT, and CCD of the rat and mouse. A triple immunolabeling procedure was developed in which antibodies to H+-ATPase and band 3 protein were used to identify subpopulations of intercalated cells, and segment-specific antibodies were used to identify distal tubule and collecting duct segments. In both rat and mouse, intercalated cells constituted approximately 40% of the cells in the CNT, ICT, and CCD. Type A, type B, and non A-non B intercalated cells were observed in all of the three segments, with type A cells being the most prevalent in both species. In the mouse, however, non A-non B cells constituted more than half of the intercalated cells in the CNT, 39% in the ICT, and 22% in the CCD, compared with 14, 7, and 5%, respectively, in the rat. In contrast, type B intercalated cells accounted for only 8 to 16% of the intercalated cells in the three segments in the mouse compared with 26 to 39% in the rat. It is concluded that striking differences exist in the prevalence and distribution of the different types of intercalated cells in the CNT, ICT, and CCD of rat and mouse. In the rat, the non A-non B cells are fairly rare, whereas in the mouse, they constitute a major fraction of the intercalated cells, primarily at the expense of the type B intercalated cells.
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Affiliation(s)
- J Kim
- Department of Anatomy, Catholic University Medical College, Seoul, Korea
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15
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Kloth S, Gmeiner T, Aigner J, Jennings ML, Röckl W, Minuth WW. Transitional stages in the development of the rabbit renal collecting duct. Differentiation 1998; 63:21-32. [PMID: 9615390 DOI: 10.1046/j.1432-0436.1998.6310021.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The collecting duct (CD) epithelium of the mammalian kidney is an extraordinary structure with respect to its functional changes during development and its heterogeneous composition when matured. All of the different nephron epithelia of the mammalian kidney consist of one single cell type. In contrast, the differentiated CD is composed of at least three distinct cell types [principal, alpha intercalated-, and beta intercalated cells] that are responsible for the multiple physiological functions of this kidney compartment. During development the function of the CD changes: initially, the CD ampulla serves as an embryonic inducer, while the matured epithelium plays a key role in maintaining the homeostasis of body fluids. At present the process of CD maturation is not well understood. Neither the time course of development nor the morphogenic factors leading to the heterogeneously composed epithelium are known. In the present study the differentiation of the CD epithelium was investigated using newly developed monoclonal antibodies and well-characterized antisera. The morphological changes induced during differentiation were monitored by immunohistochemistry and scanning electron microscopy. The experiments were performed on neonatal and adult rabbit kidneys. Results obtained by light microscopical techniques and scanning electron microscopy revealed that the ampullary tip can be distinguished from the ampullary neck, as well as from the maturing CD. A number of proteins that were not detectable in the ampulla were detected in the neonatal CD and were found at even higher concentrations in the adult CD (PCD8, chloride/bicarbonate exchanger). Other proteins (PCD9) were downregulated during differentiation. For the first time the transient character of the differentiation stage of the neonatal CD could be demonstrated unequivocally. Furthermore, considerable heterogeneity in protein expression patterns (PCD6 and PCD9) was demonstrated within the beta IC cell population of the mature CD.
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MESH Headings
- Aging
- Animals
- Antibodies, Monoclonal/metabolism
- Antigens, Differentiation/analysis
- Antigens, Differentiation/immunology
- Antiporters/metabolism
- Chloride-Bicarbonate Antiporters
- Immunohistochemistry
- Kidney Tubules, Collecting/chemistry
- Kidney Tubules, Collecting/embryology
- Kidney Tubules, Collecting/immunology
- Kidney Tubules, Collecting/ultrastructure
- Microscopy, Confocal
- Microscopy, Electron, Scanning
- Rabbits
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Affiliation(s)
- S Kloth
- Department of Anatomy, University of Regensburg, Germany
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Bates CM, Merenmies JM, Kelly-Spratt KS, Parada LF. Insulin receptor-related receptor expression in non-A intercalated cells in the kidney. Kidney Int 1997; 52:674-81. [PMID: 9291186 DOI: 10.1038/ki.1997.381] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Insulin receptor- related receptor (IRR) is a novel receptor tyrosine kinase in the insulin receptor family. Previous studies have demonstrated that the mammalian organ with the highest level of IRR mRNA is the kidney. By in situ hybridization, kidney expression of IRR transcript is only in the distal nephron and the collecting ducts; however, the specific cellular distribution of IRR is unknown. The purpose of this study was to examine IRR protein expression in the adult mouse kidney using immunohistochemical techniques. IRR was specifically present in a subset of cells in the connecting tubule, the initial collecting tubule, and the cortical collecting duct. IRR protein is detected in cells that express vacuolar H+-ATPase and carbonic anhydrase 2, but not in cells that express band 3 (anion exchanger 1). In the cortical collecting duct, the IRR positive cells are likely B intercalated cells. In the connecting tubule and the initial collecting tubule, the cells are B cells and/or non-A non-B cells. Thus, IRR is a specific marker for non-A intercalated cells in the kidney.
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Affiliation(s)
- C M Bates
- Department of Pediatrics and Center for Developmental Biology, University of Texas Southwestern Medical Center at Dallas, 75235-9133, USA
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17
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Wax MB, Saito I, Tenkova T, Krupin T, Becker B, Nelson N, Brown D, Gluck SL. Vacuolar H+-ATPase in ocular ciliary epithelium. Proc Natl Acad Sci U S A 1997; 94:6752-7. [PMID: 9192637 PMCID: PMC21230 DOI: 10.1073/pnas.94.13.6752] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The mechanisms controlling the production of aqueous humor and the regulation of intraocular pressure are poorly understood. Here, we provide evidence that a vacuolar H+-ATPase (V-ATPase) in the ocular ciliary epithelium is a key component of this process. In intracellular pH (pHi) measurements of isolated ciliary epithelium performed with 2',7-biscarboxyethyl-5(6)-carboxyfluorescein (BCECF), the selective V-ATPase inhibitor bafilomycin A1 slowed the recovery of pHi in response to acute intracellular acidification, demonstrating the presence of V-ATPase in the plasma membrane. In isolated rabbit ciliary body preparations examined under voltage-clamped conditions, bafilomycin A1 produced a concentration-dependent decrease in short-circuit current, and topical application of bafilomycin A1 reduced intraocular pressure in rabbits, indicating an essential role of the V-ATPase in ciliary epithelial ion transport. Immunocytochemistry utilizing antibodies specific for the B1 isoform of the V-ATPase 56-kDa subunit revealed localization of V-ATPase in both the plasma membrane and cytoplasm of the native ciliary epithelium in both rabbit and rat eye. The regional and subcellular distribution of V-ATPase in specific regions of the ciliary process was altered profoundly by isoproterenol and phorbol esters, suggesting that change in the intracellular distribution of the enzyme is a mechanism by which drugs, hormones, and neurotransmitters modify aqueous humor production.
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Affiliation(s)
- M B Wax
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO 63110, USA
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Al-Awqati Q. Plasticity in epithelial polarity of renal intercalated cells: targeting of the H(+)-ATPase and band 3. THE AMERICAN JOURNAL OF PHYSIOLOGY 1996; 270:C1571-80. [PMID: 8764138 DOI: 10.1152/ajpcell.1996.270.6.c1571] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The intercalated cell is an epithelial cell of the renal collecting tubule that is specialized for H+ and HCO3- transport. These cells exist as two types, alpha and beta. The alpha-cell secretes H+ into the lumen by an apical H(+)-ATPase and a basolateral Cl-/HCO3- exchanger that is a form of band 3 protein (AE1). The beta-cell secretes HCO3- into the lumen by an apical Cl-/HCO3- exchanger and a basolateral H(+)-ATPase. In a previous study, it was suggested that a reversal in epithelial polarity of these cells occurs during the response of the kidney to an acid load (G.J. Schwartz, J. Barasch, and Q. Al-Awqati. Nature Lond. 318: 368-371, 1985). Recent studies, however have shown that there are many other subtypes where the distribution of these two proteins does not fit into this neat bipolar classification. This group of investigators recently generated an immortalized cell line of the beta-intercalated cell and found that the apical Cl-/HCO3- exchanger is also AE1. Furthermore, when these cells were seeded at high densities, the polarized targeting of the apical band 3 was reversed to the basolateral membrane. This was produced by the secretion of extracellular matrix protein that by themselves were capable of reversing the polarity of band 3 (J. S. van Adelsberg, J. C. Edwards, J. Takito, B. Kiss, and Q. Al-Awqati. Cell 76: 1053-1061, 1995). A large new extracellular matrix protein, hensin, was identified and found to be present exclusively in the collecting tubule. The extensive recent literature on the biology of alpha- and beta-intercalated cells is reviewed here and found to be compatible with the idea of the reversal of polarity as a mechanism for the regulation of H+ secretion by the tubule.
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Affiliation(s)
- Q Al-Awqati
- College of Physicians and Surgeons of Columbia University, New York, New York 10032, USA
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Tsuruoka S, Schwartz GJ. Adaptation of rabbit cortical collecting duct HCO3- transport to metabolic acidosis in vitro. J Clin Invest 1996; 97:1076-84. [PMID: 8613531 PMCID: PMC507155 DOI: 10.1172/jci118500] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Net HCO3- transport in the rabbit kidney cortical collecting duct (CCD) is mediated by simultaneous H+ secretion and HCO3- secretion, most likely occurring in a alpha- and beta-intercalated cells (ICs), respectively. The polarity of net HCO3- transport is shifted from secretion to absorption after metabolic acidosis or acid incubation of the CCD. We investigated this adaptation by measuring net HCO3- flux before and after incubating CCDs 1 h at pH 6.8 followed by 2 h at pH 7.4. Acid incubation always reversed HCO3- flux from net secretion to absorption, whereas incubation for 3 h at pH 7.4 did not. Inhibition of alpha-IC function (bath CL- removal or DIDS, luminal bafilomycin) stimulated net HCO3- secretion by approximately 2 pmol/min per mm before acid incubation, whereas after incubation these agents inhibited net HCO3- absorption by approximately 5 pmol/min per mm. Inhibition of beta-IC function (luminal Cl- removal) inhibited HCO3- secretion by approximately 9 pmol/min per mm before incubation, whereas after incubation HCO3- absorption by only 3 pmol/min per mm. After acid incubation, luminal SCH28080 inhibited HCO3- absorption by only 5-15% vs the circa 90% inhibitory effect of bafilomycin. In outer CCDs, which contain fewer alpha-ICs than midcortical segments, the reversal in polarity of HCO3- flux was blunted after acid incubation. We conclude that the CCD adapts to low pH in vitro by downregulation HCO3- secretion in beta-ICs via decreased apical CL-/base exchang activity and upregulating HCO3- absorption in alpha-ICs via increased apical H+ -ATPase and basolateral CL-/base exchange activities. Whether or not there is a reversal of IC polarity or recruitment of gamma-ICs in this adaptation remains to be established.
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Affiliation(s)
- S Tsuruoka
- Department of Pediatrics, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642, USA
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20
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Abstract
The newborn has a limited ability to regulate H+/HCO3- homeostasis, due in part to immaturity of the intercalated cells in the distal nephron. We traced the postnatal differentiation of the intercalated cells of the rabbit cortical collecting duct (CCD) and outer medullary collecting duct (OMCD) using MAb to the 31-kD subunit of the vacuolar H(+)-ATPase, membrane portion of erythrocyte band 3, and apical surface of B-intercalated cells (peanut agglutinin [PNA], MAb B63). In the most superficial CCD of the newborn there was no binding to these probes, although deeper in the cortex there was faint apical staining with PNA and MAb B63 and a few patterns of H(+)-ATPase and band 3 labeling of neonatal intercalated cells. The OMCD showed mostly apical H(+)-ATPase and both cytoplasmic and basolateral band 3 labeling but B-intercalated cell markers were not seen. By 3 wk of age the staining of the CCD and OMCD was more polarized, resembling those in the adult. Band 3 positive cells (as a percentage of total cells) in the CCD increased from 13 to 17% during maturation, and in the OMCD they increased from 22 to 37%. Some basolateral band 3 and apical H(+)-ATPase staining was also seen in the inner medullary collecting duct of 3-wk-old rabbits to a greater extent than in newborn or adult rabbits. Labeling of intercalated cells in the CCD and OMCD was weakest and least numerous in the newborn, greater in the 3 wk old, and greatest in the adult. Most maturing cortical intercalated cells bound both PNA and H(+)-ATPase MAb, comparable to what has been observed in the adult CCD. PNA-negative cells showing apical H(+)-ATPase labeling, consistent with the classic A-intercalated cell phenotype, comprised only 5% of identified intercalated cells in the newborn CCD compared with 12% in older animals. In or near the developing renal vesicles and ampullary structures were occasional cytoplasmically staining PNA- and B63-positive cells. Whether these cells are precursors of specific renal tubular cells cannot yet be established. Staining for principal cells (ST.9) was less intense in the neonatal cortex than in more mature cortex, but the deep cortex and outer medulla were heavily labeled at all ages. These data indicate that immature intercalated cells, in the CCD and OMCD, may undergo significant postnatal proliferation and differentiation, acquiring mature phenotypes during the first month of life. The A-intercalated cell appears more differentiated than the B cell during the 1st wk of life, suggesting that A-intercalated cells contribute more than B cells to the maintenance of acid-base homeostasis in the newborn.
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Affiliation(s)
- T Matsumoto
- Department of Pediatrics, Albert Einstein College of Medicine, Bronx, New York, USA
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