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Thimet Oligopeptidase Forms Angiotensin‐(1–7) in the Nucleus of NRK‐52E Cells
Author(s) -
Alzayadneh Ebaa M,
Pirro Nancy T,
Chappell Mark C
Publication year - 2013
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.27.1_supplement.lb857
Subject(s) - intracellular , chemistry , renin–angiotensin system , receptor , microbiology and biotechnology , angiotensin ii , nucleus , medicine , endocrinology , biochemistry , biology , blood pressure
An intracellular renin‐angiotensin system (RAS) is evident in multiple tissues. Functional angiotensin (Ang) receptors are present intracellularly on kidney cortical nuclei; however, the intracellular pathways that contribute to Ang II or Ang‐(1–7) expression are not resolved. We sought to identify a proximal tubule epithelial cell model to elucidate the regulation of this intracellular system. Utilizing the rat‐derived NRK‐52E epithelial cell line, we demonstrate the nuclear expression of angiotensinogen (des‐Ang I Aogen), renin, AT7/Mas and prorenin receptors. Nuclear extracts of NRK cells expressed Ang‐(1–7) (51 ± 39 pg/mg protein; n=3) and immunostaining for Ang‐(1–7) was primarily confined to the nucleus. The downstream processing of 125I‐Ang I as substrate was examined in solubilized nuclear fractions by HPLC‐coupled γ‐detection. This analysis revealed the predominant conversion of Ang I to Ang‐(1–7) [41 ± 6 fmol/min/mg protein, n=4]. Both thimet oligopeptidase and thiol protease inhibitors essentially abolished Ang‐(1–7) formation [CPP: 83%; n=3 and PCMB: 85%; n=4; p<0.01 respectively]. In contrast, additional studies revealed minimal metabolism of 125I‐Ang II in the nuclear fraction [>;70 % intact at 2 hours]. Collectively, these data suggest that the localization of Aogen, renin and thimet oligopeptidase in the nucleus of NRK cells may constitute one source of intracellular Ang‐(1–7).