title: Nuclear expression of renin-angiotensin system components in NRK-52E renal epithelial cells.
abstract: BACKGROUND
  Isolated nuclei of sheep proximal tubules express angiotensin (Ang) receptors as well as angiotensinogen (AGT) and renin. The present study characterized the NRK-52E tubular epithelial cell line for the intracellular expression of renin-angiotensin system (RAS) components.
  
  
  METHODS
  RAS components were visualized by immunofluorescent staining in intact cells and protein expression in isolated nuclei.
  
  
  RESULTS
  An antibody to the angiotensin I (Ang I) sequence of AGT (AI-AGT) revealed only cytosolic staining, while an antibody to an internal sequence of AGT (Int-AGT) revealed primarily nuclear staining. Immunoblots of nuclear and cytosolic fractions confirmed the differential cell staining of AGT. Immunostaining for renin was present on nuclei of intact cells. Nuclear renin activity averaged 0.77±0.05 nmol/mg protein/h that was reduced by aliskiren (0.13±0.01 nmol/mg/h, n=3, p<0.01); trypsin activation increased activity three-fold. Peptide staining localized angiotensin II (Ang II) and Ang-(1-7) to the nucleus and peptide content averaged 59±2 and 57±22 fmol/mg (n=4), respectively. Peptide metabolism in isolated nuclei revealed the processing of Ang I to Ang-(1-7) by thimet oligopeptidase.
  
  
  CONCLUSIONS
  We conclude that the NRK-52E cells express an intracellular RAS localized to the nucleus and may be an appropriate cell model to elucidate the functional relevance of this system.
authors: The Hypertension & Vascular Research Center, Wake Forest University Health Sciences, USA.
authors: Ebaa M
authors: EM
authors: Alzayadneh
authors: The Hypertension & Vascular Research Center, Wake Forest University Health Sciences, USA mchappel@wfubmc.edu.
authors: Mark C
authors: MC
authors: Chappell
mesh_terms: D000803:Angiotensin I / Q000378:metabolism; D000804:Angiotensin II / Q000378:metabolism; D000808:Angiotensinogen / Q000378:metabolism; D000818:Animals; D002417:Cattle; D002460:Cell Line; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism*; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism*; D007668:Kidney / Q000166:cytology*; D010446:Peptide Fragments / Q000378:metabolism; D011480:Protease Inhibitors / Q000494:pharmacology; D051381:Rats; D011956:Receptors, Cell Surface / Q000378:metabolism; D012083:Renin / Q000378:metabolism; D012084:Renin-Angiotensin System / Q000187:drug effects; D012756:Sheep; D013997:Time Factors; D000093342:Prorenin Receptor
chemical_list: D010446:Peptide Fragments; D011480:Protease Inhibitors; D011956:Receptors, Cell Surface; D000808:Angiotensinogen; D000804:Angiotensin II; D000803:Angiotensin I; D012083:Renin; C118790:angiotensin I (1-7); D000093342:Prorenin Receptor
keywords: NRK-52E; angiotensin; angiotensinogen; renin; thimet oligopeptidase