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- Title
Differences in osteopontin up-regulation between proximal and distal tubules after renal ischemia/reperfusion.
- Authors
Persy, Veerle P.; Verstrepen, Walter A.; Ysebaert, Dirk K.; De Greef, Kathleen E.; De Broe, Marc E.
- Abstract
Differences in osteopontin up-regulation between proximal and distal tubules after renal ischemia/reperfusion. Background. Osteopontin (OPN) is a highly acidic phosphoprotein containing an arginine-glycine-aspartic acid (RGD) cell adhesion motif. High OPN expression has been found in tissues with high cell turnover, and OPN up-regulation has been demonstrated in several models of renal injury, suggesting a possible role in tissue remodeling and repair. However, its exact function in the kidney remains unknown. In this study, the possible contribution of OPN to regeneration and repair in the kidney was explored by studying the time course and subcellular localization of OPN up-regulation after renal ischemia/reperfusion injury in different nephron segments and by investigating its relationship with tubular morphology. Methods. Rats that underwent 60 minutes of left renal ischemia and a right nephrectomy sacrificed at 10 different time points (from 1 hr to 10 days after reperfusion) were compared with uninephrectomized rats at each time point. In renal tissue sections immunostained for OPN, proximal (PTs) and distal tubules (DTs) in both the renal cortex and outer stripe of the outer medulla (OSOM) were scored for the degree of OPN expression and tubular morphology. Results. Kidneys of uninephrectomized rats showed no injury, and the localization and intensity of their OPN expression remained unaltered compared with normal rats. After ischemia/reperfusion, morphological damage was most severe in PTs of the OSOM, but all examined nephron segments showed a significant increase in OPN expression. The time course of OPN up-regulation was different in PTs and DTs. DTs in both cortex and OSOM rapidly increased their OPN expression, with a maximum at 24 hours after reperfusion followed by a slow decrease. In contrast, PTs showed a delayed increase in OPN staining, with a maximum after five to seven days, higher in the OSOM than in the cortex. In OSOM PTs, OPN expression...
- Subjects
OSTEOPONTIN; KIDNEY injuries
- Publication
Kidney International, 1999, Vol 56, Issue 2, p601
- ISSN
0085-2538
- Publication type
Article
- DOI
10.1046/j.1523-1755.1999.00581.x