Angiotensin AT1 receptor-associated protein Arap1 in the kidney vasculature is suppressed by angiotensin II

Am J Physiol Renal Physiol. 2012 May 15;302(10):F1313-24. doi: 10.1152/ajprenal.00620.2011. Epub 2012 Feb 22.


Arap1 is a protein that interacts with angiotensin II type 1 (AT(1)) receptors and facilitates increased AT(1) receptor surface expression in vitro. In the present study, we assessed the tissue localization and regulation of Arap1 in vivo. Arap1 was found in various mouse organs, with the highest expression in the heart, kidney, aorta, and adrenal gland. Renal Arap1 protein was restricted to the vasculature and to glomerular mesangial cells and was absent from tubular epithelia. A similar localization was found in human kidneys. To test the hypothesis that angiotensin II may control renal Arap1 expression, mice were subjected to various conditions to alter the activity of the renin-angiotensin system. A high-salt diet (4% NaCl, 7 days) upregulated Arap1 expression in mice by 47% compared with controls (0.6% NaCl, P = 0.03). Renal artery stenosis (7 days) or water restriction (48 h) suppressed Arap1 levels compared with controls (-64 and -62% in the clipped and contralateral kidney, respectively; and -50% after water restriction, P < 0.01). Angiotensin II infusion (2 μg·kg(-1)·min(-1), 7 days) reduced Arap1 mRNA levels compared with vehicle by 29% (P < 0.01), whereas AT(1) antagonism (losartan, 30 mg·kg(-1)·day(-1), 7 days) enhanced Arap1 mRNA expression by 52% (P < 0.01); changes in mRNA were paralleled by Arap1 protein abundance. Experiments with hydralazine and epithelial nitric oxide synthase-/- mice further suggested that Arap1 expression changed in parallel with angiotensin II, rather than with blood pressure per se. Similar to in vivo, Arap1 mRNA and protein were suppressed by angiotensin II in a time- and dose-dependent manner in cultured mesangial cells. In summary, Arap1 is highly expressed in the renal vasculature, and its expression is suppressed by angiotensin II. Thus Arap1 may serve as a local modulator of vascular AT(1) receptor function in vivo.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptor Proteins, Signal Transducing / genetics*
  • Adaptor Proteins, Signal Transducing / metabolism
  • Angiotensin II / pharmacology*
  • Animals
  • Blood Vessels / physiology*
  • Carrier Proteins / genetics*
  • Carrier Proteins / metabolism
  • GTPase-Activating Proteins / genetics*
  • GTPase-Activating Proteins / metabolism
  • Gene Expression Regulation / drug effects
  • Gene Expression Regulation / physiology
  • Humans
  • Male
  • Mesangial Cells / physiology*
  • Mice
  • Mice, Inbred C57BL
  • Nitric Oxide Synthase Type III / genetics
  • Nitric Oxide Synthase Type III / metabolism
  • Receptor, Angiotensin, Type 1 / metabolism
  • Renal Circulation / drug effects*
  • Renal Circulation / physiology*
  • Renin / metabolism
  • Vasoconstrictor Agents / pharmacology


  • ARAP1 protein, human
  • Adaptor Proteins, Signal Transducing
  • Agtrap protein, mouse
  • Carrier Proteins
  • GTPase-Activating Proteins
  • Receptor, Angiotensin, Type 1
  • Vasoconstrictor Agents
  • Angiotensin II
  • Nitric Oxide Synthase Type III
  • Nos3 protein, mouse
  • Renin