Urine electrolyte, mineral, and protein excretion in NHERF-2 and NHERF-1 null mice

2008 ◽  
Vol 294 (4) ◽  
pp. F1001-F1007 ◽  
Author(s):  
Rochelle Cunningham ◽  
Ali Esmaili ◽  
Eric Brown ◽  
Rajat S. Biswas ◽  
Rakhilya Murtazina ◽  
...  
Keyword(s):  
Uric Acid ◽  
Urinary Excretion ◽  
Proximal Tubule ◽  
Adaptor Proteins ◽  
Renal Proximal Tubule ◽  
Wild Type ◽  
Sodium Hydrogen Exchanger ◽  
Model Cell ◽  
Abundance And Distribution ◽  
Wild Type Control

The adaptor proteins sodium/hydrogen exchanger regulatory factor (NHERF)-1 and NHERF-2 have overlapping tissue distribution in renal cells and overlapping specificity in their binding to renal transporters and other proteins. To compare the kidney-specific differences in the function of these adaptor proteins, NHERF-1 and NHERF-2 null mice were compared with wild-type control mice. In NHERF-2 null mice, the renal proximal tubule abundance and distribution of NHERF-1 and NHERF-3 were not different from those in wild-type animals. The glomerular expression of podocalyxin and ZO-1 also did not differ. NHERF-1 null mice had increased urinary excretion of phosphate, calcium, and uric acid compared with wild-type control and NHERF-2 null mice. Because of the association between NHERF-2 and podocalyxin in glomeruli and ClC-5 in the renal proximal tubule, the urinary excretion of protein was determined. There were no differences in the urinary excretion of protein or low-molecular-weight proteins between wild-type control, NHERF-1−/−, and NHERF-2−/− mice. These studies indicate that the increased urinary excretion of phosphate and uric acid are specific to NHERF-1 null mice and highlight the fact that predictions about the role of adaptor proteins such as the NHERF proteins obtained from studies of model cell systems must be confirmed in whole animals.

Longitudinal study of urinary excretion of phosphate, calcium, and uric acid in mutant NHERF-1 null mice

2006 ◽  
Vol 290 (4) ◽  
pp. F838-F843 ◽  
Author(s):  
Edward J. Weinman ◽  
Viresh Mohanlal ◽  
Nicholas Stoycheff ◽  
Fengying Wang ◽  
Deborah Steplock ◽  
...  
Keyword(s):  
Uric Acid ◽  
Urinary Excretion ◽  
Proximal Tubule ◽  
Young Male ◽  
Wild Type ◽  
Protein Targets ◽  
Male And Female ◽  
Age Related ◽  
Time Period ◽  
Apical Membranes

NHERF-1 binds numerous renal protein targets, including the proximal tubule transporters Na+/H+ exchanger 3 (NHE3) and Na+-phosphate cotransporter 2a (Npt2a). Young NHERF-1−/− male mice display defective targeting of Npt2a to apical membranes in the renal proximal tubule and manifest hypophosphatemia and increased urinary excretion of phosphate. The present studies describe the changes in the urinary excretion of phosphate, calcium, uric acid, and sodium in male and female wild-type and NHERF-1 null mice over a time period from 12 to 54 wk of age. Young male and female NHERF-1−/− mice demonstrated increased urinary excretion of phosphate and urine phosphate/creatinine ratios. There was an age-related decline in the phosphate/creatinine ratio in mutant mice such that there were no differences between wild-type and NHERF-1−/− by 24 to 30 wk of age despite the continued presence of hypophosphatemia. Male and female NHERF-1 null mice also demonstrate increased urine calcium/creatinine and uric acid/creatinine ratios compared with wild-type controls. These studies indicate defects in the renal tubule transport of phosphate, calcium, and uric acid in NHERF-1−/− male and female mice that could account for the increased deposition of calcium in the papilla of null mice.

A γGT-AT1A receptor transgene protects renal cortical structure in AT1 receptor-deficient mice

2004 ◽  
Vol 18 (3) ◽  
pp. 290-298 ◽  
Author(s):  
Thu H. Le ◽  
Michael I. Oliverio ◽  
Hyung-Suk Kim ◽  
Harmony Salzler ◽  
Rajesh C. Dash ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Transgenic Mice ◽  
Proximal Tubule ◽  
Physiological Role ◽  
Renal Proximal Tubule ◽  
Hypoxanthine Phosphoribosyl Transferase ◽  
Wild Type ◽  
Specific Expression ◽  
Low Levels ◽  
Deficient Mice

To understand the physiological role of angiotensin type 1 (AT1) receptors in the proximal tubule of the kidney, we generated a transgenic mouse line in which the major murine AT1 receptor isoform, AT1A, was expressed under the control of the P1 portion of the γ-glutamyl transpeptidase (γGT) promoter. In transgenic mice, this promoter has been shown to confer cell-specific expression in epithelial cells of the renal proximal tubule. To avoid random integration of multiple copies of the transgene, we used gene targeting to produce mice with a single-copy transgene insertion at the hypoxanthine phosphoribosyl transferase ( Hprt) locus on the X chromosome. The physiological effects of the γGT-AT1A transgene were examined on a wild-type background and in mice with targeted disruption of one or both of the murine AT1 receptor genes ( Agtr1a and Agtr1b). On all three backgrounds, γGT-AT1A transgenic mice were healthy and viable. On the wild-type background, the presence of the transgene did not affect development, blood pressure, or kidney structure. Despite relatively low levels of expression in the proximal tubule, the transgene blunted the increase in renin expression typically seen in AT1-deficient mice and partially rescued the kidney phenotype associated with Agtr1a−/− Agtr1b−/− mice, significantly reducing cortical cyst formation by more than threefold. However, these low levels of cell-specific expression of AT1 receptors in the renal proximal tubule did not increase the low blood pressures or abolish sodium sensitivity, which are characteristic of AT1 receptor-deficient mice. Although our studies do not clearly identify a role for AT1 receptors in the proximal tubules of the kidney in blood pressure homeostasis, they support a major role for these receptors in modulating renin expression and in maintaining structural integrity of the renal cortex.

scholarly journals Transgenic Overexpression of the Extra-Large Gsα Variant XLαs Enhances Gsα-Mediated Responses in the Mouse Renal Proximal Tubule in Vivo

Endocrinology ◽  
2011 ◽  
Vol 152 (4) ◽  
pp. 1222-1233 ◽  
Author(s):  
Zun Liu ◽  
Hiroko Segawa ◽  
Cumhur Aydin ◽  
Monica Reyes ◽  
Reinhold G. Erben ◽  
...  
Keyword(s):  
Proximal Tubule ◽  
Immunohistochemical Analysis ◽  
Renal Proximal Tubule ◽  
Mrna Levels ◽  
Wild Type ◽  
Western Blots ◽  
Α Subunit ◽  
Exon 1 ◽  
Serum Pth

Abstract XLαs, a variant of the stimulatory G protein α-subunit (Gsα), can mediate receptor-activated cAMP generation and, thus, mimic the actions of Gsα in transfected cells. However, it remains unknown whether XLαs can act in a similar manner in vivo. We have now generated mice with ectopic transgenic expression of rat XLαs in the renal proximal tubule (rptXLαs mice), where Gsα mediates most actions of PTH. Western blots and quantitative RT-PCR showed that, while Gsα and type-1 PTH receptor levels were unaltered, protein kinase A activity and 25-hydroxyvitamin D 1-α-hydroxylase (Cyp27b1) mRNA levels were significantly higher in renal proximal tubules of rptXLαs mice than wild-type littermates. Immunohistochemical analysis of kidney sections showed that the sodium-phosphate cotransporter type 2a was modestly reduced in brush border membranes of male rptXLαs mice compared to gender-matched controls. Serum calcium, phosphorus, and 1,25 dihydroxyvitamin D were within the normal range, but serum PTH was ∼30% lower in rptXLαs mice than in controls (152 ± 16 vs. 222 ± 41 pg/ml; P < 0.05). After crossing the rptXLαs mice to mice with ablation of maternal Gnas exon 1 (E1m−/+), male offspring carrying both the XLαs transgene and maternal Gnas exon 1 ablation (rptXLαs/E1m−/+) were significantly less hypocalcemic than gender-matched E1m−/+ littermates. Both E1m−/+ and rptXLαs/E1m−/+ offspring had higher serum PTH than wild-type littermates, but the degree of secondary hyperparathyroidism tended to be lower in rptXLαs/E1m−/+ mice. Hence, transgenic XLαs expression in the proximal tubule enhanced Gsα-mediated responses, indicating that XLαs can mimic Gsα in vivo.

scholarly journals Urinary Excretion of Tetrodotoxin Modeled in a Porcine Renal Proximal Tubule Epithelial Cell Line, LLC-PK1

Marine Drugs ◽  
2017 ◽  
Vol 15 (7) ◽  
pp. 225
Author(s):  
Takuya Matsumoto ◽  
Yui Ishizaki ◽  
Keika Mochizuki ◽  
Mitsuru Aoyagi ◽  
Yoshiharu Mitoma ◽  
...  
Keyword(s):  
Epithelial Cell ◽  
Urinary Excretion ◽  
Proximal Tubule ◽  
Cell Line ◽  
Renal Proximal Tubule ◽  
Epithelial Cell Line ◽  
Proximal Tubule Epithelial Cell

Defective PTH regulation of sodium-dependent phosphate transport in NHERF-1−/− renal proximal tubule cells and wild-type cells adapted to low-phosphate media

2005 ◽  
Vol 289 (4) ◽  
pp. F933-F938 ◽  
Author(s):  
Rochelle Cunningham ◽  
Xiaofei E ◽  
Deborah Steplock ◽  
Shirish Shenolikar ◽  
Edward J. Weinman
Keyword(s):  
Proximal Tubule ◽  
Primary Cultures ◽  
Phosphate Transport ◽  
Inhibitory Response ◽  
Renal Proximal Tubule ◽  
Wild Type ◽  
Proximal Tubule Cells ◽  
Sodium Dependent ◽  
Tubule Cells ◽  
Renal Proximal Tubule Cells

The present experiments using primary cultures from renal proximal tubule cells examine two aspects of the regulation of sodium-dependent phosphate transport and membrane sodium-dependent phosphate transporter (Npt2a) expression by parathyroid hormone (PTH). Sodium-dependent phosphate transport in proximal tubule cells from wild-type mice grown in normal-phosphate media averaged 4.4 ± 0.5 nmol·mg protein−1·10 min−1 and was inhibited by 30.5 ± 8.6% by PTH (10−7 M). This was associated with a 32.7 ± 5.2% decrease in Npt2a expression in the plasma membrane. Proximal tubule cells from Na+/H+ exchanger regulatory factor-1 (NHERF-1)−/− mice had a lower rate of phosphate transport compared with wild-type cells and a significantly reduced inhibitory response to PTH. Wild-type cells incubated in low-phosphate media for 24 h had a higher rate of phosphate transport compared with wild-type cells grown in normal-phosphate media but a significantly blunted inhibitory response to PTH. These data indicate a role for NHERF-1 in mediating the membrane retrieval of Npt2a and the subsequent inhibition of phosphate transport in renal proximal tubules. These studies also suggest that there is a blunted phosphaturic effect of PTH in cells adapted to low-phosphate media.

Sign in / Sign up

Export Citation Format

Share Document