Claudins 6, 9, and 13 are developmentally expressed renal tight junction proteins

The adult proximal tubule is a low-resistance epithelium where there are high rates of both active transcellular and passive paracellular NaCl transport. We have previously demonstrated that the neonatal rabbit and rat proximal tubule have substantively different passive paracellular transport properties than the adult proximal tubule, which results in a maturational change in the paracellular passive flux of ions. Neonatal proximal tubules have a higher PNa/PCl ratio and lower chloride and bicarbonate permeabilities than adult proximal tubules. Claudins are a large family of proteins which are the gate keepers of the paracellular pathway, and claudin isoform expression determines the permeability characteristics of the paracellular pathway. Previous studies have shown that claudins 1, 2, 3, 4, 5, 7, 8, 10, 11, 12, 15, and 16 are expressed in the adult mouse kidney. To determine whether there are developmental claudin isoforms, we compared the claudin isoforms present in the neonatal and adult kidney using RT-PCR to detect mRNA of claudin isoforms. Claudin 6, claudin 9, and claudin 13 were either not expressed or barely detectable in the adult mouse kidney using traditional PCR, but were expressed in the neonatal mouse kidney. Using real-time RT-PCR, we were able to detect a low level of claudin 6 mRNA expression in the adult kidney compared with the neonate, but claudin 9 and claudin 13 were only detected in the neonatal kidney. There was the same maturational decrease in these claudin proteins with Western blot analysis. Immunohistochemistry showed high levels of expression of claudin 6 in neonatal proximal tubules, thick ascending limb, distal convoluted tubules, and collecting ducts in a paracellular distribution but there was no expression of claudin 6 in the adult kidney. Using real-time RT-PCR claudin 6 and 9 mRNA were present in 1-day-old proximal convoluted tubules and were virtually undetectable in proximal convoluted tubules from adults. Claudin 13 was not detectable in neonatal or adult proximal convoluted tubules. In summary, we have identified developmentally expressed claudin isoforms, claudin 6, claudin 9, and claudin 13. These paracellular proteins may play a role in the maturational changes in paracellular permeability.

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Nephron-specific expression of components of the renin–angiotensin–aldosterone system in the mouse kidney

Journal of the Renin-Angiotensin-Aldosterone System ◽

10.1177/1470320311432184 ◽

2012 ◽

Vol 13 (1) ◽

pp. 46-55 ◽

Cited By ~ 7

Author(s):

Stephan W Reinhold ◽

Bernd Krüger ◽

Caroline Barner ◽

Flavius Zoicas ◽

Martin C Kammerl ◽

...

Keyword(s):

Mouse Kidney ◽

Proximal Tubules ◽

Thick Ascending Limb ◽

Specific Expression ◽

Renin Angiotensin Aldosterone System ◽

Renin Angiotensin ◽

Nephron Segments ◽

Specific Distribution ◽

Convoluted Tubules ◽

Proximal Convoluted Tubules

Introduction: The renin–angiotensin–aldosterone system (RAAS) plays an integral role in the regulation of blood pressure, electrolyte and fluid homeostasis in mammals. The capability of the different nephron segments to form components of the RAAS is only partially known. This study therefore aimed to characterize the nephron-specific expression of RAAS components within the mouse kidney. Materials and methods: Defined nephron segments of adult C57B/16 mice were microdissected after collagenase digestion. The gene expression of renin, angiotensinogen (AGT), angiotensin-converting enzyme (ACE), angiotensin II receptors 1a (AT1a), 1b (AT1b), and 2 (AT2) was assessed by reverse transcriptase polymerase chain reaction (RT-PCR). Results: Renin mRNA was present in glomeruli, in proximal tubules, in distal convoluted tubules (DCT) and cortical collecting ducts (CCD). AGT mRNA was found in proximal tubules, descending thin limb of Henle’s loop (dTL) and in the medullary part of the thick ascending limb (mTAL). ACE mRNA was not detectable in microdissected mouse nephron segments. AT1a, AT1b and AT2 mRNA was detected in glomeruli and proximal convoluted tubules. Conclusions: Our data demonstrate a nephron-specific distribution of RAAS components. All components of the local RAAS – except ACE – are present in proximal convoluted tubules, emphasizing their involvement in sodium and water handling.

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A developmentally plastic adult mouse kidney cell line spontaneously generates multiple adult kidney structures

Biochemical and Biophysical Research Communications ◽

10.1016/j.bbrc.2015.06.130 ◽

2015 ◽

Vol 463 (4) ◽

pp. 1334-1340 ◽

Cited By ~ 3

Author(s):

Carol F. Webb ◽

Michelle L. Ratliff ◽

Rebecca Powell ◽

Celeste R. Wirsig-Wiechmann ◽

Olga Lakiza ◽

...

Keyword(s):

Cell Line ◽

Kidney Cell ◽

Adult Mouse ◽

Mouse Kidney ◽

Kidney Cell Line ◽

Adult Kidney

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Development of solute transport in rabbit proximal tubule. III. Na-K-ATPase activity

AJP Renal Physiology ◽

10.1152/ajprenal.1984.246.6.f845 ◽

1984 ◽

Vol 246 (6) ◽

pp. F845-F852 ◽

Cited By ~ 5

Author(s):

G. J. Schwartz ◽

A. P. Evan

Keyword(s):

Enzyme Activity ◽

Atpase Activity ◽

Proximal Tubule ◽

Atp Hydrolysis ◽

Glucose Absorption ◽

Collagenase Treatment ◽

The Mean ◽

Convoluted Tubules ◽

Interim Period ◽

Proximal Convoluted Tubules

HCO-3 transport (JHCO-3) in early juxtamedullary proximal convoluted tubules isolated from infant rabbits during the 1st 3 wk of life is about one-third that in tubules obtained from adults. A rapid increase in transport ensues during wk 4 through 6, so that near-mature levels are attained by the end of this time. Because the pattern for development of glucose absorption was similar and because both HCO-3 and glucose absorption are driven by the lumen-to-cell Na+ flux, the activity of Na-K-ATPase (the Na+-extruding pump) was considered to be a critical mediator. A kinetic microassay (which couples ATP hydrolysis to NADH oxidation) allowed the measurement of Na-K-ATPase and ouabain-insensitive ATPase on the same tubular segment. Three to nine early juxtamedullary proximal convoluted tubules were obtained after collagenase treatment of the kidney and four to six rabbits were studied at each week of life. The mean activity of Na-K-ATPase during the 1st wk of life was 44.5 +/- 3.5 pmol X min-1 X mm-1, one-third of the adult level. During an interim period of development (2-6 wk), enzyme activity gradually reached 60% of adult levels (76.3 +/- 3.0 at 6 wk), while transport of HCO-3 and glucose, studied previously in other animals, attained mature rates. Only in the 7th wk did the enzyme activity reach that of the adult (106.8 +/- 6.8 in wk 7 vs. 128.4 +/- 14.0 in adult rabbits).(ABSTRACT TRUNCATED AT 250 WORDS)

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Mouse Kidney Androgen-Regulated Protein Messenger Ribonucleic Acid is Expressed in the Proximal Convoluted Tubules

Molecular Endocrinology ◽

10.1210/mend-1-8-535 ◽

1987 ◽

Vol 1 (8) ◽

pp. 535-541 ◽

Cited By ~ 34

Author(s):

Anna Meseguer ◽

James F. Catterall

Keyword(s):

Ribonucleic Acid ◽

Mouse Kidney ◽

Messenger Ribonucleic Acid ◽

Convoluted Tubules ◽

Proximal Convoluted Tubules

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Structural evidence for counter-current flow in proximal tubules versus peritubular capillaries in the rat kidney. Evaluation of the counter-current mechanism between the proximal convoluted tubules and the peritubular capillaries in the rat nephronNote

Apmis ◽

10.1034/j.1600-0463.2000.d01-29.x ◽

2000 ◽

Vol 108 (11) ◽

pp. 779-784 ◽

Cited By ~ 1

Author(s):

P. FAARUP ◽

N. H. HOLSTEIN-RATHLOU ◽

V. HEGEDUS

Keyword(s):

Current Flow ◽

Rat Kidney ◽

Proximal Tubules ◽

Peritubular Capillaries ◽

Counter Current Flow ◽

Counter Current ◽

Convoluted Tubules ◽

Current Mechanism ◽

Proximal Convoluted Tubules

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Hnf4a is required for the development of Cdh6-expressing progenitors into proximal tubules in the mouse kidney

10.1101/2020.02.16.951731 ◽

2020 ◽

Author(s):

Sierra S. Marable ◽

Eunah Chung ◽

Joo-Seop Park

Keyword(s):

Proximal Tubule ◽

Molecular Mechanisms ◽

Target Genes ◽

Mouse Kidney ◽

Proximal Tubules ◽

Transmembrane Transport ◽

Proximal Tubule Cells ◽

Expression Of Genes ◽

Genomic Analyses ◽

Tubule Cells

ABSTRACTBackgroundHnf4a is a major regulator of renal proximal tubule (PT) development. In humans, a mutation in HNF4A is associated with Fanconi renotubular syndrome (FRTS), which is caused by defective PT functions. In mice, mosaic deletion of Hnf4a in the developing kidney causes a paucity of PT cells, leading to FRTS-like symptoms. The molecular mechanisms underlying the role of Hnf4a in PT development remain unclear.MethodsWe generated a new Hnf4a mutant mouse model employing Osr2Cre, which effectively deletes Hnf4a in developing nephrons. We characterized the mutant phenotype by immunofluorescence analysis. We performed lineage analysis to test if Cdh6-expressing cells are PT progenitors. We also performed genome-wide mapping of Hnf4a binding sites and differential gene analysis of Hnf4a mutant kidneys to identify direct target genes of Hnf4a.ResultsDeletion of Hnf4a with Osr2Cre led to the complete loss of mature PT cells, causing lethality in the Hnf4a mutant mice. We found that Cdh6high, LTLlow cells serve as PT progenitors and that they show higher proliferation than Cdh6low, LTLhigh differentiated PT cells. We also found that Hnf4a is required for PT progenitors to develop into differentiated PT cells. Our genomic analyses revealed that Hnf4a directly regulates the expression of genes involved in transmembrane transport and metabolism.ConclusionsOur findings show that Hnf4a promotes the development of PT progenitors into differentiated PT cells by regulating the expression of genes associated with reabsorption, the major function of PT cells.SignificanceProximal tubule cells are the most abundant cell type in the mammalian kidney and they perform the bulk of the renal reabsorption function. Despite their importance in kidney function, the molecular mechanisms of proximal tubule development and maturation are not well understood. Here we find that, in the developing mouse kidney, Cdh6high, LTLlow cells act as proximal tubule progenitors and that Hnf4a is required for these cells to further develop into proximal tubules. Our genomic analyses show that Hnf4a directly regulate the expression of genes required for reabsorption such as transmembrane transport genes and metabolism genes. This study advances our understanding of how kidney proximal tubule cells form during development.

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Activation of dopamine D1-like receptors induces acute internalization of the renal Na+/phosphate cotransporter NaPi-IIa in mouse kidney and OK cells

AJP Renal Physiology ◽

10.1152/ajprenal.00380.2004 ◽

2005 ◽

Vol 288 (4) ◽

pp. F740-F747 ◽

Cited By ~ 55

Author(s):

Desa Bacic ◽

Paola Capuano ◽

Michel Baum ◽

Jianning Zhang ◽

Gerti Stange ◽

...

Keyword(s):

Proximal Tubule ◽

Brush Border Membrane ◽

Fluorescent Protein ◽

Mouse Kidney ◽

Proximal Tubules ◽

Opossum Kidney ◽

Kidney Slices ◽

Opossum Kidney Cells ◽

Green Fluorescent

The Na+/phosphate cotransporter NaPi-IIa (SLC34A1) is the major transporter mediating the reabsorption of Pi in the proximal tubule. Expression and activity of NaPi-IIa is regulated by several factors, including parathyroid hormone, dopamine, metabolic acidosis, and dietary Pi intake. Dopamine induces natriuresis and phosphaturia in vivo, and its actions on several Na+-transporting systems such as NHE3 and Na+-K+-ATPase have been investigated in detail. Using freshly isolated mouse kidney slices, perfused proximal tubules, and cultured renal epithelial cells, we examined the acute effects of dopamine on NaPi-IIa expression and localization. Incubation of isolated kidney slices with the selective D1-like receptor agonists fenoldopam (10 μM) and SKF-38393 (10 μM) for 1 h induced NaPi-IIa internalization and reduced expression of NaPi-IIa in the brush border membrane (BBM). The D2-like selective agonist quinpirole (1 μM) had no effect. The D1 and D2 agonists did not affect the renal Na+/sulfate cotransporter NaSi in the BBM of the proximal tubule. Studies with isolated perfused proximal tubules demonstrated that activation of luminal, but not basolateral, D1-like receptors caused NaPi-IIa internalization. In kidney slices, inhibition of PKC (1 μM chelerythrine) or ERK1/2 (20 μM PD-098089) pathways did not prevent the fenoldopam-induced internalization. Inhibition with the PKA blocker H-89 (10 μM) abolished the effect of fenoldopam. Immunoblot demonstrated a reduction of NaPi-IIa protein in BBMs from kidney slices treated with fenoldopam. Incubation of opossum kidney cells transfected with NaPi-IIa-green fluorescent protein chimera shifted fluorescence from the apical membrane to an intracellular pool. In summary, dopamine induces internalization of NaPi-IIa by activation of luminal D1-like receptors, an effect that is mediated by PKA.

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Role of cytoskeleton in volume regulation of rabbit proximal tubule in dilute medium

AJP Renal Physiology ◽

10.1152/ajprenal.1992.262.1.f144 ◽

1992 ◽

Vol 262 (1) ◽

pp. F144-F150 ◽

Cited By ~ 4

Author(s):

M. A. Linshaw ◽

C. A. Fogel ◽

G. P. Downey ◽

E. W. Koo ◽

A. I. Gotlieb

Keyword(s):

Proximal Tubule ◽

Volume Regulation ◽

Cytochalasin B ◽

Proximal Tubules ◽

Hypotonic Medium ◽

Microtubule Inhibitor ◽

Volume Regulatory Decrease ◽

Convoluted Tubules ◽

Dilute Medium

When proximal tubules are immersed in hypotonic medium, they quickly swell to a peak volume. In a second, slower phase, termed volume regulatory decrease (VRD), they shrink as K, anion, and water leave the cells. We investigated the role of the cytoskeleton during this biphasic hypotonic volume regulatory response. Isolated, collapsed rabbit proximal convoluted tubules (PCT) were crimped tightly between two pipettes, and their volume was assessed optically. PCT volume increased to a peak 70-80% above baseline on sudden immersion in dilute medium (150 mosmol/kgH2O). After completing VRD, control tubules had regulated their volume 73 +/- 2% back toward baseline. Tubules exposed to the microtubule inhibitor vincristine (5 microM) regulated 75 +/- 2%. Tubules exposed to the microfilament inhibitor cytochalasin B (50 microM) regulated less (57 +/- 5%), and tubules exposed to both inhibitors regulated only 39 +/- 3% (P less than 0.01 vs. control). Hypotonic VRD was unimpaired in PCT loaded with NaCl by prior exposure to ouabain but was significantly reduced by cytochalasin B. We conclude that VRD is not cation specific and that intact microtubules and microfilaments play a synergistic role in the VRD of rabbit PCT in hyposmotic medium.

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Potassium permeability in the absence of fluid reabsorption in proximal tubule of the anesthetized rat

AJP Renal Physiology ◽

10.1152/ajprenal.1998.274.6.f1109 ◽

1998 ◽

Vol 274 (6) ◽

pp. F1109-F1112

Author(s):

Rod W. Wilson ◽

Mark Wareing ◽

Jon Kibble ◽

Roger Green

Keyword(s):

Proximal Tubule ◽

Potassium Concentration ◽

Arithmetic Mean ◽

Apparent Permeability ◽

Fluid Reabsorption ◽

Potassium Permeability ◽

Anesthetized Rats ◽

Potassium Flux ◽

Convoluted Tubules ◽

Proximal Convoluted Tubules

A luminal microperfusion technique was used to examine the K+ permeability of surface proximal convoluted tubules (PCT) in the kidney of anesthetized rats. Transtubular potassium concentration ([K+]) gradients were varied by altering the concentration of KCl in luminal perfusates, to which 32 mmol/l of the impermeant solute raffinose was also added to prevent net fluid reabsorption. The arithmetic mean transtubular [K+] gradient was highly predictive of net potassium flux, yielding an apparent K+ permeability of 31.9 ± 1.7 × 10−5 cm/s in the absence of fluid reabsorption. When compared using identical calculation techniques, we found this was not significantly different from the permeability derived in a previous study when fluid reabsorption was present [J. D. Kibble, M. Wareing, R. W. Wilson, and R. Green. Am. J. Physiol. 268 ( Renal Fluid Electrolyte Physiol. 27): F778–F783, 1995]. We conclude that fluid reabsorption does not affect the apparent permeability of the proximal tubule to potassium. The apparent permeability to86Rb, measured following its addition to luminal perfusates, was not significantly different from the value obtained for K+, suggesting that rubidium is a useful marker for net potassium movements in the PCT of the rat.

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