Nuclear angiotensin-(1-7) receptor is functionally coupled to the formation of nitric oxide

• Published in: American Journal of Physiology - Renal Physiology Vol. 299; no. 5; pp. F983 - F990
• Main Authors: Gwathmey, Tanya M, Westwood, Brian M, Pirro, Nancy T, Tang, Lijun, Rose, James C, Diz, Debra I, Chappell, Mark C
• Format: Journal Article
• Language: English
• Published: United States American Physiological Society 01.11.2010
• Subjects: ACE inhibitors; Angiotensin II - analogs & derivatives; Angiotensin II - metabolism; Angiotensin-Converting Enzyme Inhibitors - pharmacology; Animals; Blotting, Western; Cell Nucleus - metabolism; Cells; Enzyme Inhibitors - pharmacology; Female; Fluorescent Antibody Technique; Gene expression; Immunohistochemistry; Kidney - metabolism; Kidney Cortex - metabolism; Kidney Tubules, Proximal - metabolism; Kidneys; Male; NG-Nitroarginine Methyl Ester - pharmacology; Nitric oxide; Nitric Oxide - biosynthesis; Nitric Oxide - physiology; Nitric Oxide Synthase Type III - antagonists & inhibitors; Nitric Oxide Synthase Type III - biosynthesis; Peptide Hydrolases - metabolism; Peptidyl-Dipeptidase A - metabolism; Proteins; Proto-Oncogene Mas; Proto-Oncogene Proteins - metabolism; Radioligand Assay; Receptors, Angiotensin - metabolism; Receptors, G-Protein-Coupled - metabolism; Renin-Angiotensin System - physiology; Sheep; Studies; T cell receptors
• ISSN: 1931-857X; 0363-6127; 1522-1466
• DOI: 10.1152/ajprenal.00371.2010

The kidney is an important target for the actions of the renin-angiotensin system (RAS) and this tissue contains a complete local RAS that expresses the bioactive peptides angiotensin II (ANG II) and Ang-(1-7). We find both angiotensin type 1 (AT(1)R) and type 2 (AT(2)R) receptors expressed on renal nuclei that stimulate reactive oxygen species and nitric oxide (NO), respectively. Since Ang-(1-7) also exhibits actions within the kidney and the Ang-(1-7)/Mas receptor protein contains a nuclear localization sequence, we determined the expression of Ang-(1-7) receptors in nuclei isolated from the kidneys of young adult sheep. Binding studies with (125)I-[Sar(1)Thr(8)]-ANG II revealed sites sensitive to the Ang-(1-7) antagonist [d-Ala(7)]-Ang-(1-7) (DALA, A779), as well as to AT(2) and AT(1) antagonists. Incubation of Ang-(1-7) [10(-15) to 10(-9) M] with isolated cortical nuclei elicited a dose-dependent increase in the fluorescence of the NO indicator [4-amino-5-methylamino-2',7']-difluorofluorescein diacetate. The NO response to Ang-(1-7) was abolished by the NO inhibitor N-nitro-l-arginine methyl ester and DALA, but not the AT(1) antagonist losartan or the AT(2) blocker PD123319. Immunofluorescent studies utilizing the Ang-(1-7)/Mas receptor antibody revealed immunolabeling of the proximal tubules but not staining within the glomerulus in cortical sections of the sheep kidney. In the nuclear fraction of isolated proximal tubules, immunoblots revealed the precursor angiotensinogen and renin, as well as functional activity for ACE, ACE2, and neprilysin. We conclude that renal nuclei express Ang-(1-7)/Mas receptors that are functionally linked to NO formation. The marked sensitivity of the intracellular NO response to Ang-(1-7) implicates a functional role of the Ang-(1-7) axis within the nucleus. Moreover, evidence for the precursor and enzymatic components of the RAS within the nuclear compartment of the proximal tubules provides a potential pathway for the intracellular generation of Ang-(1-7).