Interaction with grp58 increases activity of the thiazide-sensitive Na-Cl cotransporter

2002 ◽  
Vol 282 (3) ◽  
pp. F424-F430 ◽  
Author(s):  
Bruce Wyse ◽  
Nawb Ali ◽  
David H. Ellison
Keyword(s):  
Rat Kidney ◽  
Glucose Deprivation ◽  
Kidney Cortex ◽  
Xenopus Laevis Oocytes ◽  
Rat Kidney Cortex ◽  
Sodium Uptake ◽  
Sodium Chloride Cotransporter ◽  
Important Interaction ◽  
Hybrid Screening

The thiazide-sensitive sodium-chloride cotransporter (NCC) is expressed by distal convoluted tubule cells of the mammalian kidney. We used yeast two-hybrid screening to identify that glucose-regulated protein 58 (grp58), a protein induced by glucose deprivation, binds to the COOH terminus of the NCC. Immunoprecipitation of rat kidney cortex homogenates using a guinea pig anti-NCC antibody confirmed that grp58 associates with the NCC in vivo. Northern blots indicated that grp58 is highly expressed in rat kidney cortex. Immunofluorescence showed that grp58 protein abundance in kidney is highest in epithelial cells of the distal nephron, where it colocalizes with NCC near the apical membrane. To determine whether this interaction has a functional significance, NCC and grp58 cRNA were coexpressed in Xenopus laevis oocytes. In oocytes overexpressing grp58, sodium uptake was increased compared with control. Because oocytes express endogenous grp58, antisense experiments were performed to evaluate whether endogenous grp58 affected NCC activity in oocytes. Sodium uptake was lower in oocytes injected with both antisense grp58 cRNA and sense NCC compared with sense NCC oocytes. Western blot analysis did not show any effect of grp58 expression on processing of the NCC. These data indicate a novel, functionally important interaction between grp58 and the NCC in rat kidney cortex.

Regulation of sgk by aldosterone and its effects on the epithelial Na+ channel

2000 ◽  
Vol 278 (4) ◽  
pp. F613-F619 ◽  
Author(s):  
Alexander Shigaev ◽  
Carol Asher ◽  
Hedva Latter ◽  
Haim Garty ◽  
Eitan Reuveny
Keyword(s):  
De Novo ◽  
Rat Kidney ◽  
Kidney Cortex ◽  
Na Channel ◽  
Xenopus Laevis Oocytes ◽  
Fourfold Increase ◽  
Tight Epithelia ◽  
High Level

Aldosterone is the major corticosteroid regulating Na+ absorption in tight epithelia and acts primarily by activating the epithelial Na+ channel (ENaC) through unknown induced proteins. Recently, it has been reported that aldosterone induces the serum- and glucocorticoid-dependent kinase sgk and that coexpressing ENaC with this kinase in Xenopus laevis oocytes increases the amiloride-sensitive Na+current (Chen SY, Bhargava A, Mastroberardino L, Meijer OC, Wang J, Buse P, Firestone GL, Verrey F, and Pearce D. Proc Natl Acad Sci USA 96: 2514–2519, 1999). The present study was done to further characterize regulation of sgk by aldosterone in native mammalian epithelia and to examine its effect on ENaC. With both in vivo and in vitro protocols, an almost fivefold increase in the abundance of sgk mRNA has been demonstrated in rat kidney and colon but not in lung. Induction of sgk by aldosterone was detected in kidney cortex and medulla, whereas the papilla expressed a constitutively high level of the kinase. The increase in sgkmRNA was detected as early as 30 min after the hormonal application and was independent of de novo protein synthesis. The observed aldosterone dose-response relationships suggest that the response is mediated, at least in part, by occupancy of the mineralocorticoid receptor. Coexpressing sgk and ENaC in Xenopus oocytes evoked a fourfold increase in the amiloride-blockable Na+ channel activity. A point mutation in the β-subunit known to impair regulation of the channel by Nedd4 (Y618A) had no significant effect on the response to sgk.

scholarly journals A role for bicarbonate in the regulation of mammalian glutamine metabolism

1979 ◽  
Vol 184 (3) ◽  
pp. 599-606 ◽  
Author(s):  
G Baverel ◽  
P Lund
Keyword(s):  
Rat Kidney ◽  
Glutamine Metabolism ◽  
Kidney Cortex ◽  
Complete Oxidation ◽  
Kidney Tubules ◽  
Acid Base Balance ◽  
Acid Base ◽  
Rat Kidney Cortex ◽  
Base Balance

1. The concentration of HCO3- (independent of any change of pH) exerts different effects on glutamine metabolism in rat kidney-cortex tubules, hepatocytes and enterocytes.2. In kidney tubules HCO3- (10.5-50 MM) has no effect on glutaminase (EC 3.5.1.2), whereas glutamate dehydrogenase (EC 1.4.1.3) is inhibited as HCO3- concentration is increased. The result is that flux through the entire glutamate-to-glucose pathway is inhibited by increasing HCO3- concentrations. A large proportion (more than 30%) of the glutamine removed undergoes complete oxidation. 3. In hepatocytes, and to a smaller extent in enterocytes, HCO3- is an accelerator of glutaminase. Synthesis of glucose and urea from glutamine in hepatocytes increases as HCO3- concentration is increased. Calculations show that fumarate, formed via aspartate aminotransferase and arginino-succinate lyase, is the precursor of the glucose. There is no complete oxidation of the carbon skeleton of glutamine in hepatocytes. 4. Leucine at near-physiological concentrations (0.1-1 mM) is an accelerator of glutaminase in hepatocytes, but not in kidney tubules or in enterocytes. 5. The results are discussed in relation to regulation of acid/base balance in vivo.

In vivo generation of hydrogen peroxide by rat kidney cortex and glomeruli

1989 ◽  
Vol 256 (1) ◽  
pp. F158-F164 ◽  
Author(s):  
B. R. Guidet ◽  
S. V. Shah
Keyword(s):  
Hydrogen Peroxide ◽  
Catalase Activity ◽  
Renal Cortex ◽  
Specific Activity ◽  
Rat Kidney ◽  
Kidney Cortex ◽  
Compound I ◽  
Rat Kidney Cortex ◽  
Hydrogen Peroxide Generation

The purpose of this study was to demonstrate in vivo generation of hydrogen peroxide by rat renal cortex and glomeruli. Aminotriazole irreversibly inactivates catalase only in the presence of hydrogen peroxide, and previous studies have shown that aminotriazole-mediated inhibition of catalase is a measure of in vivo changes in the hydrogen peroxide generation. Aminotriazole injected intraperitoneally caused a dose-dependent (0.1-1 g/kg) and a time-dependent (15, 30, 60, 90, 120 min) inhibition of the catalase activity in renal cortex. We confirmed that catalase inactivation by aminotriazole was due to formation of a catalase-hydrogen peroxide intermediate (compound I) because catalase inactivation was prevented by ethanol (2 g/kg), a competitive substrate for compound I. The specific activity of catalase in the glomeruli [0.27 +/- 0.026 k/mg protein (where k is the first-order reaction rate constant), n = 5] was significantly lower than the specific activity in the tubules (1.04 +/- 0.15 k/mg protein, n = 5) obtained from the same rats. The residual catalase activity (RCA) in the glomeruli (0.05 +/- 0.01 k/mg protein) was 19% of control values at 90 min after aminotriazole injection (1 g/kg). Taken together these data provide evidence for in vivo generation of hydrogen peroxide by rat renal cortex and glomeruli under normal conditions. Aminotriazole-mediated inhibition of catalase has been used in previous studies as a measure of in vivo changes in the hydrogen peroxide generation.(ABSTRACT TRUNCATED AT 250 WORDS)

Renal glucose production and uptake in separate sites, and its significance

1962 ◽  
Vol 203 (3) ◽  
pp. 572-576 ◽  
Author(s):  
William P. McCann
Keyword(s):  
Glucose Metabolism ◽  
Rat Kidney ◽  
Glucose Production ◽  
Metabolic Energy ◽  
Kidney Cortex ◽  
Rat Kidney Cortex ◽  
Nephron Segments ◽  
Collecting Ducts ◽  
Cortical Slices

Slices of rat kidney cortex, medulla, and papilla were incubated in serum under O2-CO2 mixtures, and their glucose exchanges measured. Cortical slices released more glucose than can be explained by glycogen or other tissue glucose forms, or slice swelling. Medullary and papillary slices, however, rapidly took up glucose, even when NaCl and/or urea were added to the serum to mimic probable in vivo conditions for these tissues. Renal glucose metabolism is discussed on the basis of these and other observations, leading to the following premises: a) glucose is formed in and released from proximal convolutions, while it is less certain that this occurs in distal convolutions; b) loops and collecting ducts, if not other nephron segments, may rely heavily on glucose for metabolic energy; and c) there are circumstantial relations between net renal glucose metabolism and diuresis.

scholarly journals Expression of a rat renal sodium-dependent dicarboxylate transporter in Xenopus oocytes

1994 ◽  
Vol 297 (1) ◽  
pp. 35-39 ◽  
Author(s):  
J Steffgen ◽  
S Kienle ◽  
F Scheyerl ◽  
H E Franz
Keyword(s):  
Xenopus Oocytes ◽  
Rat Kidney ◽  
Ph Dependence ◽  
Hill Coefficient ◽  
Kidney Cortex ◽  
Xenopus Laevis Oocytes ◽  
Rat Kidney Cortex ◽  
Maximal Activation ◽  
Sodium Dependent ◽  
In Trans

Microinjection of mRNA isolated from rat kidney cortex into Xenopus laevis oocytes resulted in the expression of a Na(+)-dependent dicarboxylate transporter, as detected by uptake measurements with [14C]succinate as substrate. The expressed transporter showed an S-shaped Na(+)-dependence with half-maximal activation at 19-21 mM Na+ and a Hill coefficient between 2 and 3. Endogenous succinate uptake was not Na(+)-dependent. Na(+)-stimulated succinate uptake in mRNA-injected oocytes exhibited a maximum at pH 7.5, whereas endogenous Na(+)-independent transporter was fastest at pH 8.5. The expressed dicarboxylate transporter also differed from the endogenous transporter in its sensitivity to citrate as well as dicarboxylates in trans and cis configurations. The expressed transporter resembled the renal basolateral transporter, especially with respect to affinity for succinate (Km 28 microM), activation by Na+, pH-dependence and substrate specificity. After injection of size-fractionated mRNA, succinate uptake was expressed by mRNA of 2-3 kb. Our results suggest expression of the basolateral Na(+)-dependent dicarboxylate transporter after injection of mRNA from rat kidney into Xenopus oocytes.

scholarly journals Accumulation of Sulfate by Mitochondria of Rat Kidney Cortex

1962 ◽  
Vol 45 (4) ◽  
pp. 757-775 ◽  
Author(s):  
Robert W. Winters ◽  
Adelaide M. Delluva ◽  
Ingrith J. Deyrup ◽  
Robert E. Davies
Keyword(s):  
Rat Kidney ◽  
Kidney Cortex ◽  
Ph Optimum ◽  
Rat Kidney Cortex ◽  
Sulfate Ions ◽  
Straight Line ◽  
Freundlich Adsorption Isotherm ◽  
Ambient Concentrations

Twice washed mitochondria from rat kidney cortex can accumulate sulfate ions from low (10-7 M) ambient concentrations to create virtual gradients of several hundred to one. This sulfate is subsequently released. The activation energy for the uptake is 12,000 calories per mole; for release it is about 30,000 calories per mole. Variations in the sulfate concentration of the medium show that there is a straight line Freundlich adsorption isotherm over a million-fold range of concentration of sulfate in the medium. There are 9 x 104 sites at 10-5 M and 9 x 105 sites at 10-3 M sulfate per average single mitochondrion. Preincubation at 30°C rapidly destroys the ability to accumulate sulfate. Partial protection occurs if oxidative phosphorylation is proceeding during the preincubation. The concentration of the endogenous inorganic sulfate of twice washed mitochondria is 4.2 x 10-4 moles per liter of mitochondrial pellet water; 99.85 per cent of this endogenous sulfate is inexchangeable with external sulfate in vitro. It is all exchangeable in vivo. The pH optimum for accumulation of radiosulfate from dilute external sulfate concentrations is 5.5. These observations show that there is a delicate and specific mechanism in mitochondria from kidney cortex which accumulates sulfate. The chemical nature of the accumulated sulfate is unknown.

Rat kidney MAP17 induces cotransport of Na-mannose and Na-glucose inXenopus laevisoocytes

2003 ◽  
Vol 285 (4) ◽  
pp. F799-F810 ◽  
Author(s):  
Tatiana Blasco ◽  
José J. Aramayona ◽  
Ana I. Alcalde ◽  
Julia Catalán ◽  
Manuel Sarasa ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Transport System ◽  
Rat Kidney ◽  
Kidney Cortex ◽  
Seminiferous Tubules ◽  
Xenopus Laevis Oocytes ◽  
Breast Carcinomas ◽  
Rat Kidney Cortex ◽  
Molecular Identity ◽  
Dependent Transport

Renal reabsorption is the main mechanism that controls mannose homeostasis. This takes place through a specific Na-coupled uphill transport system, the molecular identity of which is unknown. We prepared and screened a size-selected rat kidney cortex cDNA library through the expression of mannose transport in Xenopus laevis oocytes. We have identified a membrane protein that induces high-affinity and specific Na-dependent transport of d-mannose and d-glucose in X. laevis oocytes, most likely through stimulation of the capacity of an endogenous transport system of the oocyte. Sequencing has revealed that the cDNA encodes the counterpart of the human membrane-associated protein MAP17, previously known by its overexpression in renal, colon, lung, and breast carcinomas. We show that MAP17 is a 12.2-kDa nonglycosylated membrane protein that locates to the brush-border plasma membrane and the Golgi apparatus of transfected cells and that it is expressed in the proximal tubules of the kidney cortex and in the spermatids of the seminiferous tubules. It spans twice the cell membrane, with both termini inside the cell, and seems to form homodimers through intracellular Cys55, a residue also involved in transport expression. MAP17 is responsible for mannose transport expression in oocytes by rat kidney cortex mRNA. The induced transport has the functional characteristics of a Na-glucose cotransporter (SGLT), because d-glucose and α-methyl-d-glucopyranoside are also accepted substrates that are inhibited by phloridzin. The corresponding transporter from the proximal tubule remains to be identified, but it is different from the known mammalian SGLT-1, -2, and -3.

scholarly journals 3-Mercaptopicolinic acid, an inhibitor of gluconeogenesis

1974 ◽  
Vol 138 (3) ◽  
pp. 387-394 ◽  
Author(s):  
N. W. DiTullio ◽  
C. E. Berkoff ◽  
B. Blank ◽  
V. Kostos ◽  
E. J. Stack ◽  
...  
Keyword(s):  
Rat Kidney ◽  
Diabetic Rats ◽  
Kidney Cortex ◽  
Hepatic Glycogen ◽  
Hypoglycaemic Effect ◽  
Rat Kidney Cortex ◽  
Urea Production ◽  
Rat Livers

1. 3-Mercaptopicolinic acid (SK&F 34288) inhibited gluconeogenesis in vitro, with lactate as substrate, in rat kidney-cortex and liver slices. 2. In perfused rat livers, gluconeogenesis was inhibited when lactate, pyruvate or alanine served as substrate, but not with fructose, suggesting pyruvate carboxylase or phosphoenolpyruvate carboxylase as the site of inhibition. No significant effects were evident in O2 consumption, hepatic glycogen, urea production, or [lactate]/[pyruvate] ratios. 3. A hypoglycaemic effect was evident in vivo in starved and alloxan-diabetic rats, starved guinea pigs and starved mice, but not in 4h-post-absorptive rats. 4. In the starved rat the hypoglycaemia was accompanied by an increase in blood lactate. 5. A trace dose of [14C]lactate in vivo was initially oxidized to a lesser extent in inhibitor-treated rats, but during 90min the total CO2 evolved was slightly greater. The total amount of the tracer oxidized was not significantly different from that in the controls.

scholarly journals Cellular Accumulation of L-Cystine in Rat Kidney Cortex In Vivo

1973 ◽  
Vol 52 (2) ◽  
pp. 454-462 ◽  
Author(s):  
Warren E. Greth ◽  
Samuel O. Their ◽  
Stanton Segal
Keyword(s):  
Rat Kidney ◽  
Kidney Cortex ◽  
Rat Kidney Cortex ◽  
Cellular Accumulation
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