Ischemia-induced cleavage of cadherins in NRK cells is not sufficient for beta-catenin transcriptional activity

Cell Commun Adhes. 2007 Oct;14(4):111-23. doi: 10.1080/15419060701556943.

Abstract

Although ischemia is associated with disruption of cadherin-mediated adhesion in renal cell lines, the impact of decreased cadherin function on the transcriptional activity of beta-catenin remains poorly defined. In these studies, we used a simulated ischemia model in normal rat kidney (NRK) cells to disrupt cadherin function. Cell viability; cadherin/catenin expression, function, and localization; and beta-catenin-mediated transcriptional activity were assessed during ischemia/reperfusion. Following 6 hr of ischemia, a decrease in the expression of E- and N-cadherin was seen that correlated with altered cell morphology indicative of decreased intercellular adhesion. While ischemia was associated with activation of glycogen synthase kinase 3 beta (GSK-3beta), this did not correlate with increased phosphorylation of beta-catenin as assessed by Western blots using phosphoryl-specific antibodies. beta-Catenin was not localized to the nucleus by immunofluorescence in ischemic NRK cells, but rather a strong perinuclear signal was seen in reperfused cells. This was consistent with the finding that neither ischemia nor reperfusion activated the transcriptional activity of beta-catenin as assessed by the TCF-optimal promoter (TOPFlash) construct. However, NRK cells possess a competent Wnt pathway, as challenge with lithium chloride elicited a ten-fold increase in luciferase activity. These results suggest that ischemia-induced disruption of cadherin/catenin complexes is not sufficient to stimulate beta-catenin transcriptional activity in NRK cells.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Adenosine Triphosphate / metabolism
  • Animals
  • Blotting, Western
  • Cadherins / metabolism*
  • Cells, Cultured
  • Fluorescent Antibody Technique
  • Glycogen Synthase Kinase 3 / metabolism
  • Glycogen Synthase Kinase 3 beta
  • Immunoprecipitation
  • Ischemia / metabolism*
  • Kidney / cytology
  • Kidney / drug effects
  • Kidney / metabolism*
  • Luciferases / metabolism
  • Promoter Regions, Genetic
  • Rats
  • Signal Transduction
  • TCF Transcription Factors / genetics
  • TCF Transcription Factors / metabolism
  • Transcription, Genetic*
  • Transcriptional Activation
  • Wnt Proteins / metabolism
  • beta Catenin / genetics*
  • beta Catenin / metabolism

Substances

  • Cadherins
  • TCF Transcription Factors
  • Wnt Proteins
  • beta Catenin
  • Adenosine Triphosphate
  • Luciferases
  • Glycogen Synthase Kinase 3 beta
  • Gsk3b protein, rat
  • Glycogen Synthase Kinase 3