Dynamics of E-cadherin and gamma-catenin complexes during dedifferentiation of polarized MDCK cells.
BACKGROUND
E-cadherin mediated cell-cell adhesion and hepatocyte growth factor (HGF) are important for renal epithelial morphogenesis. We previously showed that HGF dedifferentiates previously well polarized Madin-Darby canine kidney (MDCK) cell monolayers grown on filters. The regulation of E-cadherin during epithelial dedifferentiation is not known. We hypothesized that E-cadherin mediated cell-cell adhesion is modulated during HGF induced dedifferentiation of MDCK cell monolayers.


METHODS
We analyzed E-cadherin/gamma-catenin interaction and distribution during epithelial dedifferentiation in vitro using a model of polarized MDCK cell monolayers treated with HGF.


RESULTS
Surface immunoprecipitation experiments showed that HGF increased the amount of cell surface E-cadherin associated with gamma-catenin. Biochemical and morphological examination of the TX-100 solubility of junctional E-cadherin and gamma-catenin in control and HGF treated cells showed an increase in solubility of only E-cadherin during loss of cell polarity. Metabolic labeling of control and HGF treated cells showed that HGF stimulated the synthetic rate of E-cadherin and gamma-catenin molecules. Inulin flux across MDCK cell monolayers increases with HGF treatment.


CONCLUSIONS
These data provide evidence for both the dissociation of E-cadherin molecules from the actin cytoskeleton and an increase in the total number of E-cadherin/gamma-catenin complexes on the cell surface during HGF-induced dedifferentiation of polarized renal epithelium. These data support the hypothesis that E-cadherin function is inhibited by a mechanism of detachment from the actin based cytoskeleton during HGF induced dedifferentiation of polarized renal epithelia.
Balkovetz
D F
DF
Department of Veterans Affairs, Medical Center, and Department of Medicine, Nephrology Research Training Center, University of Alabama at Birmingham, 35294-0007, USA. balkovetz@nrtc.dom.uab.edu
Sambandam
V
V
D000199:Actins / Q000502:physiology; D000818:Animals; D015820:Cadherins / Q000737:chemistry / Q000378:metabolism*; D002448:Cell Adhesion / Q000502:physiology; D002454:Cell Differentiation / Q000502:physiology*; D002462:Cell Membrane / Q000187:drug effects / Q000502:physiology; D016764:Cell Polarity / Q000502:physiology*; D003598:Cytoskeletal Proteins / Q000737:chemistry / Q000378:metabolism*; D003599:Cytoskeleton / Q000502:physiology; D051180:Desmoplakins; D004285:Dogs; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D017228:Hepatocyte Growth Factor / Q000494:pharmacology; D007444:Inulin / Q000493:pharmacokinetics; D007668:Kidney / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D046911:Macromolecular Substances; D008954:Models, Biological; D015398:Signal Transduction; D051185:gamma Catenin
D000199:Actins; D015820:Cadherins; D003598:Cytoskeletal Proteins; D051180:Desmoplakins; D046911:Macromolecular Substances; D051185:gamma Catenin; D017228:Hepatocyte Growth Factor; D007444:Inulin