Enzymatic processing of angiotensin peptides by human glomerular endothelial cells. Am J Physiol Renal Physiol 2012 Jun 15;302(12):F1583-94
Date
03/31/2012Pubmed ID
22461301Pubmed Central ID
PMC3378096DOI
10.1152/ajprenal.00087.2012Scopus ID
2-s2.0-84862621036 (requires institutional sign-in at Scopus site) 39 CitationsAbstract
The intraglomerular renin-angiotensin system (RAS) is linked to the pathogenesis of progressive glomerular diseases. Glomerular podocytes and mesangial cells play distinct roles in the metabolism of angiotensin (ANG) peptides. However, our understanding of the RAS enzymatic capacity of glomerular endothelial cells (GEnCs) remains incomplete. We explored the mechanisms of endogenous cleavage of ANG substrates in cultured human GEnCs (hGEnCs) using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and isotope-labeled peptide quantification. Overall, hGEnCs metabolized ANG II at a significantly slower rate compared with podocytes, whereas the ANG I processing rate was comparable between glomerular cell types. ANG II was the most abundant fragment of ANG I, with lesser amount of ANG-(1-7) detected. Formation of ANG II from ANG I was largely abolished by an ANG-converting enzyme (ACE) inhibitor, whereas ANG-(1-7) formation was decreased by a prolylendopeptidase (PEP) inhibitor, but not by a neprilysin inhibitor. Cleavage of ANG II resulted in partial conversion to ANG-(1-7), a process that was attenuated by an ACE2 inhibitor, as well as by an inhibitor of PEP and prolylcarboxypeptidase. Further fragmentation of ANG-(1-7) to ANG-(1-5) was mediated by ACE. In addition, evidence of aminopeptidase N activity (APN) was demonstrated by detecting amelioration of conversion of ANG III to ANG IV by an APN inhibitor. While we failed to find expression or activity of aminopeptidase A, a modest activity attributable to aspartyl aminopeptidase was detected. Messenger RNA and gene expression of the implicated enzymes were confirmed. These results indicate that hGEnCs possess prominent ACE activity, but modest ANG II-metabolizing activity compared with that of podocytes. PEP, ACE2, prolylcarboxypeptidase, APN, and aspartyl aminopeptidase are also enzymes contained in hGEnCs that participate in membrane-bound ANG peptide cleavage. Injury to specific cell types within the glomeruli may alter the intrarenal RAS balance.
Author List
Velez JC, Ierardi JL, Bland AM, Morinelli TA, Arthur JM, Raymond JR, Janech MGAuthor
John R. Raymond MD President Emeritus MCW, Professor in the President department at Medical College of WisconsinMESH terms used to index this publication - Major topics in bold
Angiotensin IAngiotensin II
Carboxypeptidases
Cells, Cultured
Endothelial Cells
Humans
Kidney Glomerulus
Neprilysin
Peptidyl-Dipeptidase A
Podocytes
Renin-Angiotensin System
