title: Evidence for a mitochondrial angiotensin-(1-7) system in the kidney.
abstract: Evidence for an intracellular renin-angiotensin system (RAS) in various cell organelles now includes the endoplasmic reticulum, nucleus, and mitochondria (Mito). Indeed, angiotensin (ANG) AT1and AT2receptor subtypes were functionally linked to Mito respiration and nitric oxide production, respectively, in previous studies. We undertook a biochemical analysis of the Mito RAS from male and female sheep kidney cortex. Mito were isolated by differential centrifugation followed by a discontinuous Percoll gradient and were coenriched in Mito membrane markers VDAC and ATP synthase, but not β-actin or cathepsin B. Two distinct renin antibodies identified a 37-kDa protein band in Mito; angiotensinogen (Aogen) conversion was abolished by the inhibitor aliskiren. Mito Aogen was detected by an Aogen antibody to an internal sequence of the protein, but not with an antibody directed against the ANG I N terminus. ANG peptides were quantified by three direct RIAs; mitochondrial ANG II and ANG-(1-7) contents were higher compared with ANG I (23 ± 8 and 58 ± 17 vs. 2 ± 1 fmol/mg protein;P< 0.01,n= 3).125I-ANG I metabolism primarily revealed the formation of125I-ANG-(1-7) in Mito that reflects the endopeptidases neprilysin and thimet oligopeptidase. Last, immunoblot studies utilizing the ANG-(1-7)/Mas receptor antibody revealed the protein in isolated Mito from sheep renal cortex. Collectively, the current data demonstrate that Mito actively metabolize the RAS precursor protein Aogen, suggesting that ANG-(1-7) may be generated within Mito to establish an intramitochondrial RAS tone and contribute to renal mitochondrial function.
authors.affiliation: Hypertension and Vascular Research Center, Wake Forest University School of Medicine, Winston-Salem, North Carolina.
authors.forename: Bryan A
authors.initials: BA
authors.lastname: Wilson
authors.affiliation: Division of Endocrinology, Diabetes, and Metabolism, University of Florida, Gainesville, Florida.
authors.forename: Manisha
authors.initials: M
authors.lastname: Nautiyal
authors.affiliation: Hypertension and Vascular Research Center, Wake Forest University School of Medicine, Winston-Salem, North Carolina.
authors.forename: TanYa M
authors.initials: TM
authors.lastname: Gwathmey
authors.affiliation: Department of Obstetrics and Gynecology, Wake Forest University School of Medicine, Winston-Salem, North Carolina; and.
authors.forename: James C
authors.initials: JC
authors.lastname: Rose
authors.affiliation: Hypertension and Vascular Research Center, Wake Forest University School of Medicine, Winston-Salem, North Carolina; mchappel@wakehealth.edu.
authors.forename: Mark C
authors.initials: MC
authors.lastname: Chappell
mesh_terms: D000803:Angiotensin I / Q000378:metabolism*; D000808:Angiotensinogen / Q000378:metabolism*; D000818:Animals; D005260:Female; D007668:Kidney / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism*; D010446:Peptide Fragments / Q000378:metabolism*; D012083:Renin / Q000378:metabolism*; D012084:Renin-Angiotensin System / Q000502:physiology*; D012756:Sheep
chemical_list: D010446:Peptide Fragments; D000808:Angiotensinogen; D000803:Angiotensin I; D012083:Renin; C118790:angiotensin I (1-7)
keywords: ANG-(1–7); angiotensin-(1–7); kidney; mitochondria; renin-angiotensin system