title: Ischemia-induced cleavage of cadherins in NRK cells is not sufficient for beta-catenin transcriptional activity.
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.
authors.affiliation: Department of Systems Biology and Translational Medicine, College of Medicine, Texas A&M University System Health Science Center, Texas, USA.
authors.forename: Gang
authors.initials: G
authors.lastname: Chen
authors.forename: Adebayo D
authors.initials: AD
authors.lastname: Akintola
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Catania
authors.forename: Marisa D
authors.initials: MD
authors.lastname: Covington
authors.forename: Dana D
authors.initials: DD
authors.lastname: Dean
authors.forename: Jerome P
authors.initials: JP
authors.lastname: Trzeciakowski
authors.forename: Robert C
authors.initials: RC
authors.lastname: Burghardt
authors.forename: Alan R
authors.initials: AR
authors.lastname: Parrish
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D015153:Blotting, Western; D015820:Cadherins / Q000378:metabolism*; D002478:Cells, Cultured; D005455:Fluorescent Antibody Technique; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism; D000071679:Glycogen Synthase Kinase 3 beta; D047468:Immunoprecipitation; D007511:Ischemia / Q000378:metabolism*; D007668:Kidney / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D008156:Luciferases / Q000378:metabolism; D011401:Promoter Regions, Genetic; D051381:Rats; D015398:Signal Transduction; D051820:TCF Transcription Factors / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D051153:Wnt Proteins / Q000378:metabolism; D051176:beta Catenin / Q000235:genetics* / Q000378:metabolism
chemical_list: D015820:Cadherins; D051820:TCF Transcription Factors; D051153:Wnt Proteins; D051176:beta Catenin; D000255:Adenosine Triphosphate; D008156:Luciferases; D000071679:Glycogen Synthase Kinase 3 beta; C000605508:Gsk3b protein, rat; D038362:Glycogen Synthase Kinase 3