title: Reductive metabolism of AGE precursors: a metabolic route for preventing AGE accumulation in cardiovascular tissue.
abstract: OBJECTIVE
  To examine the role of aldo-keto reductases (AKRs) in the cardiovascular metabolism of the precursors of advanced glycation end products (AGEs).
  
  
  METHODS
  Steady-state kinetic parameters of AKRs with AGE precursors were determined using recombinant proteins expressed in bacteria. Metabolism of methylglyoxal and AGE accumulation were studied in human umbilical vein endothelial cells (HUVECs) and C57 wild-type, akr1b3 (aldose reductase)-null, cardiospecific-akr1b4 (rat aldose reductase), and akr1b8 (FR-1)-transgenic mice. AGE accumulation and atherosclerotic lesions were studied 12 weeks after streptozotocin treatment of C57, akr1b3-null, and apoE- and akr1b3-apoE-null mice.
  
  
  RESULTS
  Higher levels of AGEs were generated in the cytosol than at the external surface of HUVECs cultured in high glucose, indicating that intracellular metabolism may be an important regulator of AGE accumulation and toxicity. In vitro, AKR 1A and 1B catalyzed the reduction of AGE precursors, whereas AKR1C, AKR6, and AKR7 were relatively ineffective. Highest catalytic efficiency was observed with AKR1B1. Acetol formation in methylglyoxal-treated HUVECs was prevented by the aldose reductase inhibitor sorbinil. Acetol was generated in hearts perfused with methylglyoxal, and its formation was increased in akr1b4- or akr1b8-transgenic mice. Reduction of AGE precursors was diminished in hearts from akr1b3-null mice. Diabetic akr1b3-null mice accumulated more AGEs in the plasma and the heart than wild-type mice, and deletion of akr1b3 increased AGE accumulation and atherosclerotic lesion formation in apoE-null mice.
  
  
  CONCLUSIONS
  Aldose reductase-catalyzed reduction is an important pathway in the endothelial and cardiac metabolism of AGE precursors, and it prevents AGE accumulation and atherosclerotic lesion formation.
authors: Diabetes and Obesity Center, University of Louisville, Louisville, Kentucky, USA.
authors: Shahid P
authors: SP
authors: Baba
authors: Oleg A
authors: OA
authors: Barski
authors: Yonis
authors: Y
authors: Ahmed
authors: Timothy E
authors: TE
authors: O'Toole
authors: Daniel J
authors: DJ
authors: Conklin
authors: Aruni
authors: A
authors: Bhatnagar
authors: Sanjay
authors: S
authors: Srivastava
mesh_terms: D000449:Aldehyde Reductase / Q000378:metabolism; D000818:Animals; D001057:Apolipoproteins E / Q000172:deficiency; D004730:Endothelium, Vascular / Q000378:metabolism; D017127:Glycation End Products, Advanced / Q000096:biosynthesis / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D008055:Lipids / Q000502:physiology; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009206:Myocardium / Q000201:enzymology; D010084:Oxidation-Reduction; D011765:Pyruvaldehyde / Q000378:metabolism*; D014471:Umbilical Veins / Q000378:metabolism
chemical_list: D001057:Apolipoproteins E; D017127:Glycation End Products, Advanced; D008055:Lipids; D011765:Pyruvaldehyde; D000449:Aldehyde Reductase