scholarly journals Deletion of the angiotensin II type 1 receptor–associated protein enhances renal sodium reabsorption and exacerbates angiotensin II–mediated hypertension

2014 ◽  
Vol 86 (3) ◽  
pp. 570-581 ◽  
Author(s):  
Masato Ohsawa ◽  
Kouichi Tamura ◽  
Hiromichi Wakui ◽  
Akinobu Maeda ◽  
Toru Dejima ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Sodium Reabsorption ◽  
Receptor Associated Protein ◽  
Renal Sodium Reabsorption

Involvement of Runx3 in the basal transcriptional activation of the mouse angiotensin II type 1 receptor-associated protein gene

2011 ◽  
Vol 43 (14) ◽  
pp. 884-894 ◽  
Author(s):  
Miyuki Matsuda ◽  
Kouichi Tamura ◽  
Hiromichi Wakui ◽  
Toru Dejima ◽  
Akinobu Maeda ◽  
...  
Keyword(s):  
Gene Expression ◽  
Angiotensin Ii ◽  
Transcriptional Activation ◽  
At1 Receptor ◽  
Distal Convoluted Tubule ◽  
Luciferase Assay ◽  
Serum Starvation ◽  
Receptor Associated Protein ◽  
Tubule Cells

We previously cloned a molecule that interacts with angiotensin II type 1 (AT1) receptor to exert an inhibitory function on AT1 receptor signaling that we named ATRAP/ Agtrap (for AT1 receptor-associated protein). In the present study we examined the regulation of basal ATRAP gene expression using renal distal convoluted tubule cells. We found that serum starvation upregulated basal expression of ATRAP gene, a response that required de novo mRNA and protein synthesis. Luciferase assay revealed that the proximal promoter region directs transcription and that a putative binding site of runt-related transcription factors (RBE) is important for transcriptional activation. The results of RBE-decoy transfection and endogenous knockdown by small interference RNA showed that the runt-related transcription factor Runx3 is involved in ATRAP gene expression. Chromatin immunoprecipitation assay also supported the binding of Runx3 to the ATRAP promoter in renal distal convoluted tubule cells. Immunohistochemistry demonstrated the expression of Runx3 and ATRAP proteins in the distal convoluted and connecting tubules of the kidney in consecutive sections. Furthermore, the Runx3 immunostaining was decreased together with a concomitant suppression of ATRAP expression in the affected kidney after 7 days of unilateral ureteral obstruction. These findings indicate that Runx3 plays a role in ATRAP gene expression in renal distal tubular cells both in vitro and in vivo.

Stimulation of renal sodium reabsorption by angiotensin II

1977 ◽  
Vol 232 (4) ◽  
pp. F298-F306 ◽  
Author(s):  
M. D. Johnson ◽  
R. L. Malvin
Keyword(s):  
Blood Flow ◽  
Angiotensin Ii ◽  
Flow Rate ◽  
Sodium Reabsorption ◽  
Urinary Flow ◽  
Filtration Fraction ◽  
Water Diuresis ◽  
Urinary Osmolality ◽  
Anesthetized Dogs ◽  
Renal Sodium Reabsorption

Various parameters of renal function were studied before, during, and after the infusion of physiological increments of angiotensin II directly into one renal artery of anesthetized dogs. During water diuresis and during antidiuresis induced with exogenous antidiuretic hormone (ADH), angiotensin II consistently reduced UNaV, UKV, and CPAH, and increased the filtration fraction in the infused kidney. Urinary osmolality was increased only in the presence of ADH, while during water diuresis angiotensin II had no apparent effect on urinary osmolality or flow rate. During saline diuresis, a mean increment of angiotensin II concentration of 14 pg/ml was sufficient to significantly reduce UNaV and urinary flow rate. Changes in CCr, CPAH, and filtration fraction did not correlate with changes in sodium excretion, and intracortical distribution of blood flow remained unaltered. These data support the hypothesis that normal circulating levels of angiogensin II play a direct renal role in the control of sodium, potassium, and water homeostasis, and that angiotensin II exerts a direct, stimulatory effect on tubular sodium reabsorption independent of changes in GFR, RPF, filtration fraction, or intracortical distribution of blood flow.

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