title: Differential expression of E-cadherin, N-cadherin and beta-catenin in proximal and distal segments of the rat nephron.
abstract: BACKGROUND
  The classical cadherins such as E- and N-cadherin are Ca2+-dependent cell adhesion molecules that play important roles in the development and maintenance of renal epithelial polarity. Recent studies have shown that a variety of cadherins are present in the kidney and are differentially expressed in various segments of the nephron. However, the interpretation of these findings has been complicated by the fact that the various studies focused on different panels of cadherins and utilized different species. Moreover, since only a few of the previous studies focused on the rat, information regarding the expression and localization of renal cadherins in this important species is lacking. In the present study, we have employed dual immunofluorescent labeling procedures that utilized specific antibodies against either E- or N-cadherin, along with antibodies that target markers for specific nephron segments, to characterize the patterns of cadherin expression in frozen sections of adult rat kidney.
  
  
  RESULTS
  The results showed that N-cadherin is the predominant cadherin in the proximal tubule, but is essentially absent in other nephron segments. By contrast, E-cadherin is abundant in the distal tubule, collecting duct and most medullary segments, but is present only at very low levels in the proximal tubule. Additional results revealed different patterns of N-cadherin labeling along various segments of the proximal tubule. The S1 and S2 segments exhibit a fine threadlike pattern of labeling at the apical cell surface, whereas the S3 segment show intense labeling at the lateral cell-cell contacts.
  
  
  CONCLUSIONS
  These results indicate that E- and N-cadherin are differentially expressed in the proximal and distal tubules of rat kidney and they raise the possibility that differences in cadherin expression and localization may contribute to the differences in the susceptibility of various nephron segments to renal pathology or nephrotoxic injury.
authors.affiliation: Department of Pharmacology, Midwestern University, Downers Grove, IL 60515, USA. wprozi@midwestern.edu
authors.forename: Walter C
authors.initials: WC
authors.lastname: Prozialeck
authors.forename: Peter C
authors.initials: PC
authors.lastname: Lamar
authors.forename: Denah M
authors.initials: DM
authors.lastname: Appelt
mesh_terms: D000818:Animals; D051398:Aquaporin 1; D051399:Aquaporin 2; D020346:Aquaporins / Q000276:immunology; D015820:Cadherins / Q000235:genetics* / Q000276:immunology; D003598:Cytoskeletal Proteins / Q000235:genetics* / Q000276:immunology; D019084:Fluorescent Antibody Technique, Indirect / Q000379:methods; D005786:Gene Expression Regulation / Q000235:genetics*; D007685:Kidney Tubules, Collecting / Q000737:chemistry; D007686:Kidney Tubules, Distal / Q000737:chemistry*; D007687:Kidney Tubules, Proximal / Q000737:chemistry*; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D015534:Trans-Activators / Q000235:genetics* / Q000276:immunology; D051176:beta Catenin
chemical_list: C496022:Aqp1 protein, rat; C496025:Aqp2 protein, rat; D051399:Aquaporin 2; D020346:Aquaporins; D015820:Cadherins; C495268:Ctnnb1 protein, rat; D003598:Cytoskeletal Proteins; D015534:Trans-Activators; D051176:beta Catenin; D051398:Aquaporin 1