scholarly journals Mechanisms whereby extracellular adenosine 3',5'-monophosphate inhibits phosphate transport in cultured opossum kidney cells and in rat kidney. Physiological implication.

1992 ◽  
Vol 90 (3) ◽  
pp. 848-858 ◽  
Author(s):  
G Friedlander ◽  
S Couette ◽  
C Coureau ◽  
C Amiel
Keyword(s):  
Rat Kidney ◽  
Phosphate Transport ◽  
Kidney Cells ◽  
Extracellular Adenosine ◽  
Opossum Kidney ◽  
Opossum Kidney Cells

Interactions of cubilin with megalin and the product of the amnionless gene (AMN): effect on its stability

2008 ◽  
Vol 410 (2) ◽  
pp. 301-308 ◽  
Author(s):  
Rajiv Ahuja ◽  
Raghunatha Yammani ◽  
Joseph A. Bauer ◽  
Seema Kalra ◽  
Shakuntla Seetharam ◽  
...  
Keyword(s):  
Rat Kidney ◽  
Intrinsic Factor ◽  
Transmembrane Proteins ◽  
Immunohistochemical Analysis ◽  
Protein Product ◽  
Kidney Cells ◽  
Opossum Kidney ◽  
Opossum Kidney Cells ◽  
Polarized Epithelia

Cubilin, a 456 kDa multipurpose receptor lacking in both transmembrane and cytoplasmic domains is expressed in the apical BBMs (brush border membranes) of polarized epithelia. Cubilin interacts with two transmembrane proteins, AMN, a 45–50 kDa protein product of the amnionless gene, and megalin, a 600 kDa giant endocytic receptor. In vitro, three fragments of cubilin, the 113-residue N-terminus and CUB domains 12–17 and 22–27, demonstrated Ca2+-dependent binding to megalin. Immunoprecipitation and immunoblotting studies using detergent extracts of rat kidney BBMs revealed that cubilin interacts with both megalin and AMN. Ligand (intrinsic factor–cobalamin)-affinity chromatography showed that in renal BBMs, functional cubilin exists as a complex with both AMN and megalin. Cubilin and AMN levels were reduced by 80% and 55–60% respectively in total membranes and BBMs obtained from kidney of megalin antibody-producing rabbits. Immunohistochemical analysis and turnover studies for cubilin in megalin or AMN gene-silenced opossum kidney cells showed a significant reduction (85–90%) in cubilin staining and a 2-fold decrease in its half-life. Taken together, these results indicate that three distinct regions of cubilin bind to megalin and its interactions with both megalin and AMN are essential for its intracellular stability.

scholarly journals Phosphorylation of rat kidney Na-K pump at Ser938 is required for rapid angiotensin II-dependent stimulation of activity and trafficking in proximal tubule cells

2016 ◽  
Vol 310 (3) ◽  
pp. C227-C232 ◽  
Author(s):  
Katherine J. Massey ◽  
Quanwen Li ◽  
Noreen F. Rossi ◽  
Susan M. Keezer ◽  
Raymond R. Mattingly ◽  
...  
Keyword(s):  
Plasma Membranes ◽  
Rat Kidney ◽  
Proximal Tubules ◽  
Kidney Cells ◽  
Ang Ii ◽  
Wild Type ◽  
Stimulate Activity ◽  
Opossum Kidney ◽  
Opossum Kidney Cells ◽  
Stimulation Of

How angiotensin (ANG) II acutely stimulates the Na-K pump in proximal tubules is only partially understood, limiting insight into how ANG II increases blood pressure. First, we tested whether ANG II increases the number of pumps in plasma membranes of native rat proximal tubules under conditions of rapid activation. We found that exposure to 100 pM ANG II for 2 min, which was previously shown to increase affinity of the Na-K pump for Na and stimulate activity threefold, increased the amount of the Na-K pump in plasma membranes of native tubules by 33%. Second, we tested whether previously observed increases in phosphorylation of the Na-K pump at Ser938 were part of the stimulatory mechanism. These experiments were carried out in opossum kidney cells, cultured proximal tubules stably coexpressing the ANG type 1 (AT1) receptor, and either wild-type or a S938A mutant of rat kidney Na-K pump under conditions found by others to stimulate activity. We found that 10 min of incubation in 10 pM ANG II stimulated activity of wild-type pumps from 2.3 to 3.5 nmol K·mg protein−1·min−1 and increased the amount of the pump in the plasma membrane by 80% but had no effect on cells expressing the S938A mutant. We conclude that acute stimulation of Na-K pump activity in native rat proximal tubules includes increased trafficking to the plasma membrane and that phosphorylation at Ser938 is part of the mechanism by which ANG II directly stimulates activity and trafficking of the rat kidney Na-K pump in opossum kidney cells.

Hormonal Regulation of Sodium-Dependent Phosphate Transport in Opossum Kidney Cells

2000 ◽  
Vol 54 (1) ◽  
pp. 38-43 ◽  
Author(s):  
Douglas M. Silverstein ◽  
Adrian Spitzer ◽  
Mario Barac-Nieto
Keyword(s):  
Hormonal Regulation ◽  
Phosphate Transport ◽  
Kidney Cells ◽  
Opossum Kidney ◽  
Opossum Kidney Cells ◽  
Sodium Dependent

Modulation of Na+-Pi cotransport in opossum kidney cells by extracellular phosphate

1988 ◽  
Vol 255 (2) ◽  
pp. C155-C161 ◽  
Author(s):  
J. Biber ◽  
J. Forgo ◽  
H. Murer
Keyword(s):  
Actinomycin D ◽  
Phosphate Transport ◽  
Kidney Cells ◽  
Transport Activity ◽  
Similar Extent ◽  
Opossum Kidney ◽  
Ok Cells ◽  
Opossum Kidney Cells ◽  
Dependent Transport ◽  
Posttranscriptional Level

The effect of the extracellular concentration of Pi on the Na+-dependent phosphate transport activity of OK cells was investigated. When incubated with extracellular Pi at concentrations of 200 microM or less, Na+-Pi cotransport increased approximately twofold in OK cells compared with control cells (kept in 0.85 mM Pi), whereas other Na+-dependent transport activities were not affected. After Pi deprivation, Na+-Pi cotransport could be inhibited to a similar extent (80%) by parathyroid hormone (PTH) as in control cells, suggesting that the PTH-sensitive Na+-Pi cotransport activity is also regulated by extracellular Pi. The increase of Na+-Pi cotransport was maximally expressed after 6 h and could be prevented by cycloheximide (70 microM) but not by actinomycin D (0.5-5 g/ml). However, the adaptive response was completely blocked by 3'-deoxyadenosine (cordycepin) at 100 microM. From these data, it is concluded that the upregulation of Na+-Pi cotransport in OK cells due to low extracellular Pi is controlled at a posttranscriptional level.

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