Selective degradation of E-cadherin and dissolution of E-cadherin-catenin complexes in epithelial ischemia

Am J Physiol Renal Physiol. 2000 May;278(5):F847-52. doi: 10.1152/ajprenal.2000.278.5.F847.

Abstract

Ischemic epithelial cells are characterized by disruption of intercellular junctions and loss of apical-basolateral protein polarity, which are normally dependent on the integrity of the adherens junction (AJ). Biochemical analysis of both whole ischemic kidneys and ATP-depleted Madin-Darby canine kidney (MDCK) cells demonstrated a striking loss of E-cadherin (the transmembrane protein of the AJ) with the appearance and accumulation of an approximately 80-kDa fragment reactive with anti-E-cadherin antibodies on Western blots of ATP-depleted MDCK cells. This apparent ischemia-induced degradation of E-cadherin was not blocked by either inhibitors of the major proteolytic pathways (i.e., proteasome, lysosome, or calpain), or by chelation of intracellular calcium, suggesting the involvement of a protease capable of functioning at low ATP and low calcium levels. Immunocytochemistry revealed the movement of several proteins normally comprising the AJ, including E-cadherin and beta-catenin, away from lateral portions of the plasma membrane to intracellular sites. Moreover, rate-zonal centrifugation and immunoprecipitation with anti-E-cadherin and anti-beta-catenin antibodies indicated that ATP depletion disrupted normal E-cadherin-catenin interactions, resulting in the dissociation of alpha- and gamma-catenin from E-cadherin and beta-catenin-containing complexes. Because the generation and maintenance of polarized epithelial cells are dependent upon E-cadherin-mediated cell-cell adhesion and normal AJ function, we propose that the rapid degradation of E-cadherin and dissolution of the AJ is a key step in the development of the ischemic epithelial cell phenotype. Furthermore, we hypothesize that the reassembly of the AJ after ischemia/ATP depletion may require a novel bioassembly mechanism involving recombination of newly synthesized and sorted E-cadherin with preexisting pools of catenins that have (temporally) redistributed intracellularly.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adenosine Triphosphate / metabolism
  • Animals
  • Cadherins / metabolism*
  • Cell Adhesion
  • Cell Line
  • Cell Polarity
  • Cytoskeletal Proteins / metabolism*
  • Dogs
  • Epithelial Cells / metabolism
  • Intercellular Junctions / metabolism
  • Ischemia / metabolism*
  • Kidney / blood supply*
  • Kidney / cytology
  • Kidney / metabolism*
  • Rats
  • Rats, Sprague-Dawley
  • Trans-Activators*
  • beta Catenin

Substances

  • Cadherins
  • Ctnnb1 protein, rat
  • Cytoskeletal Proteins
  • Trans-Activators
  • beta Catenin
  • Adenosine Triphosphate