Characterization of renin-angiotensin system enzyme activities in cultured mouse podocytes. Am J Physiol Renal Physiol 2007 Jul;293(1):F398-407
Date
04/13/2007Pubmed ID
17429035DOI
10.1152/ajprenal.00050.2007Scopus ID
2-s2.0-34548047701 (requires institutional sign-in at Scopus site) 83 CitationsAbstract
Intraglomerular ANG II has been linked to glomerular injury. However, little is known about the contribution of podocytes (POD) to intraglomerular ANG II homeostasis. The aim of the present study was to examine the processing of angiotensin substrates by cultured POD. Our approach was to use matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry for peptide determination from conditioned cell media and customized AQUA peptides for quantification. Immortalized mouse POD were incubated with 1-2 microM ANG I, ANG II, or the renin substrate ANG-(1-14) for different time intervals and coincubated in parallel with various inhibitors. Human mesangial cells (MES) were used as controls. POD incubated with 1 microM ANG I primarily formed ANG-(1-9) and ANG-(1-7). In contrast, MES incubated with ANG I primarily generated ANG II. In POD, ANG-(1-7) was the predominant product, and its formation was inhibited by a neprilysin inhibitor. Modest angiotensin-converting enzyme (ACE) activity was also detected in POD, although only after cells were incubated with 2 microM ANG I. In addition, we observed that POD degraded ANG II into ANG III and ANG-(1-7). An aminopeptidase A inhibitor inhibited ANG III formation, and an ACE2 inhibitor led to ANG II accumulation. Furthermore, we found that POD converted ANG-(1-14) to ANG I and ANG-(1-7). This conversion was inhibited by a renin inhibitor. These findings demonstrate that POD express a functional intrinsic renin-angiotensin system characterized by neprilysin, aminopeptidase A, ACE2, and renin activities, which predominantly lead to ANG-(1-7) and ANG-(1-9) formation, as well as ANG II degradation. These findings may reflect a specific role of POD in maintenance of intraglomerular renin-angiotensin system balance.
Author List
Velez JC, Bland AM, Arthur JM, Raymond JR, Janech MGAuthor
John R. Raymond MD President, CEO, Professor in the President department at Medical College of WisconsinMESH terms used to index this publication - Major topics in bold
Angiotensin IAngiotensin II
Animals
CD13 Antigens
Cells, Cultured
Glutamyl Aminopeptidase
Humans
Mesangial Cells
Mice
Neprilysin
Peptide Fragments
Peptidyl-Dipeptidase A
Podocytes
Protease Inhibitors
Renin
Renin-Angiotensin System
Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization