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This Article Full Text Full Text (PDF) All Versions of this Article: 289/4/F911    most recent 00037.2005v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (2) Citing Articles via Google Scholar Google Scholar Articles by Mathew, R. Articles by Trachtman, H. Search for Related Content PubMed PubMed Citation Articles by Mathew, R. Articles by Trachtman, H.

Meprin- in chronic diabetic nephropathy: interaction with the renin-angiotensin axis

¹Division of Nephrology, Department of Pediatrics, Schneider's Children's Hospital of the North Shore-Long Island Jewish Health System, Long Island Campus for the Albert Einstein College of Medicine, and ²Department of Pathology, Schneider's Children's Hospital, New Hyde Park, New York; and ³Department of Biochemistry and Molecular Biology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania

Submitted 28 January 2005 ; accepted in final form 3 June 2005

Meprin (MEP) A is a metalloendopeptidase that is present in the renal proximal tubule brush-border membrane (BBM) and that colocalizes with angiotensin-converting enzyme (ACE). The MEP -chain gene locus on chromosome 18 has been linked to a heightened risk of diabetic nephropathy (DN) in patients with type 2 diabetes. This study evaluated 1) whether MEP- and MEP- gene and protein expression are altered in db/db mice before the onset of DN and 2) the role of MEP- in the pathogenesis of DN and the impact of the renin-angiotensin system on this interaction in two experimental models of diabetes. MEP- and MEP- gene and protein expression were evaluated in db/db mice, 13–14 wk of age, compared with lean C57BLKS/J littermate animals. A treatment study was then performed in which db/db mice and controls were assigned to one of three groups: control (C) water, no therapy; ACE inhibitor therapy, enalapril (EN)-treated water, 50 mg/l; ANG II receptor type 1 blocker (ARB) therapy, losartan (LOS)-treated water, 500 mg/l. Treatment was started at 8 wk of age and continued for 52 wk. Male Sprague-Dawley rats with diabetes for 52 wk following a single dose of streptozocin (STZ; 60 mg/kg) were also studied. At 13.5 wk of age, MEP- and MEP- kidney mRNA abundance and protein expression were significantly lower in db/db mice compared with lean controls, with greater changes in MEP- (P < 0.05). In the treatment study, EN ameliorated and LOS exacerbated DN in db/db mice. BBM MEP A enzymatic activity and MEP- protein content were lower in db/db mice vs. control nonobese mice at 52 wk (P < 0.02). EN-treated db/db mice showed increased MEP A activity, MEP- content in BBM, decreased urinary MEP- excretion, and enhanced BBM staining for MEP- protein vs. C and LOS-treated db/db mice. In nonobese mice, EN and LOS treatment had no effect on MEP- expression. In rats with STZ-induced diabetes for 52 wk, urinary MEP- excretion was increased and MEP A activity and MEP- protein content per milligram of BBM protein were decreased compared with age-matched control animals (P < 0.05). These results indicate that db/db mice manifest decreased MEP- and MEP- gene and protein expression, before the development of overt kidney disease. Moreover, in db/db mice with DN and rats with STZ-diabetes, there was an inverse relationship between renal MEP- content and the severity of the renal injury. Treatment with an ACE inhibitor was more effective than ARB in ameliorating DN in db/db mice, a change that correlated with alterations in urinary excretion and BBM content of MEP-. MEP- may play a role in the pathogenesis of DN and the benefits of ACE inhibitor therapy on the progression of diabetic kidney disease may be related, in part, to its impact on renal MEP- expression.

diabetes; angiotensin-converting enzyme; kidney disease

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