Mass spectrometry for the molecular imaging of angiotensin metabolism in kidney
- 15 April 2012
- journal article
- research article
- Published by American Physiological Society in American Journal of Physiology-Endocrinology and Metabolism
- Vol. 302 (8), E1016-E1024
- https://doi.org/10.1152/ajpendo.00515.2011
Abstract
To better understand the tissue distribution and activity of enzymes involved in angiotensin II (Ang II) processing, we developed a novel molecular imaging method using matrix-assisted laser desorption ionization-time-of-flight (MALDI-TOF) mass spectrometry. Mouse kidney sections (12 μm) were incubated with 10–1,000 μmol/l Ang II for 5–15 min at 37°C. The formed peptides Ang III and Ang-(1–7) were identified by MALDI-TOF/TOF. A third metabolite, Ang-(1–4), was generated from further degradation of Ang-(1–7). Enzymatic processing of Ang II was dose and time dependent and absent in heat-treated kidney sections. Distinct spatial distribution patterns (pseudocolor images) were observed for the peptides. Ang III was localized in renal medulla, whereas Ang-(1–7)/Ang-(1–4) was present in cortex. Regional specific peptide formation was confirmed using microdissected cortical and medullary biopsies. In vitro studies with recombinant enzymes confirmed activity of peptidases known to generate Ang III or Ang-(1–7) from Ang II: aminopeptidase A (APA), Ang-converting enzyme 2 (ACE2), prolyl carboxypeptidase (PCP), and prolyl endopeptidase (PEP). Renal medullary Ang III generation was blocked by APA inhibitor glutamate phosphonate. The ACE2 inhibitor MLN-4760 and PCP/PEP inhibitor Z-pro-prolinal reduced cortical Ang-(1–7) formation. Our results establish the power of MALDI imaging as a highly specific and information-rich analytical technique that will further aid our understanding of the role and site of Ang II processing in cardiovascular and renal pathologies.Keywords
This publication has 63 references indexed in Scilit:
- Multiple Statistical Analysis Techniques Corroborate Intratumor Heterogeneity in Imaging Mass Spectrometry Datasets of MyxofibrosarcomaPLOS ONE, 2011
- Intrarenal Renin Angiotensin System RevisitedJournal of Biological Chemistry, 2010
- Nuclear angiotensin-(1–7) receptor is functionally coupled to the formation of nitric oxideAmerican Journal of Physiology-Renal Physiology, 2010
- Fine Mapping the Spatial Distribution and Concentration of Unlabeled Drugs within Tissue Micro-Compartments Using Imaging Mass SpectrometryPLOS ONE, 2010
- Detecting low-abundance vasoactive peptides in plasma: Progress toward absolute quantitation using nano liquid chromatography–mass spectrometryAnalytical Biochemistry, 2009
- Intrarenal angiotensin II and angiotensinogen augmentation in chronic angiotensin II-infused miceAmerican Journal of Physiology-Renal Physiology, 2008
- Renin‐angiotensin system revisitedJournal of Internal Medicine, 2008
- Enhancement of protein sensitivity for MALDI imaging mass spectrometry after chemical treatment of tissue sectionsJournal of the American Society for Mass Spectrometry, 2008
- Simultaneous analysis of angiotensin peptides by LC–MS and LC–MS/MS: Metabolism by bovine adrenal endothelial cellsAnalytical Biochemistry, 2007
- Altered blood pressure responses and normal cardiac phenotype in ACE2-null miceJCI Insight, 2006