Endocytosis of junctional cadherins in bovine kidney epithelial (MDBK) cells cultured in low Ca2+ ion medium

J Cell Biol. 1991 May;113(4):881-92. doi: 10.1083/jcb.113.4.881.

Abstract

The release of intercellular contacts in MDBK cells, initiated by the depletion of Ca2+ ions from the culture medium, results in the endocytotic uptake of membrane vesicles containing specific membrane constituents of the zonula adhaerens (ZA). During this process the junction-derived, endocytosed vesicles remain associated with the ZA plaque components, while the plaque and its attached actin filaments retract as a whole in a ring-like fashion from the plasma membrane, often accumulating, usually in fragments, in the juxtanuclear cytoplasm. Double-label immunofluorescence microscopy with antiplakoglobin and antivinculin has indicated that both plaque proteins colocalize with the hallmark membrane glycoprotein of this junction type, E-cadherin (uvomorulin). When HRP used as a fluid phase marker is applied to the culture medium, simultaneously with the Ca2+ ion-chelator EGTA, numerous HRP-positive vesicles are found in close association with the dislocated plaque material, suggesting that the HRP is contained in the vesicles formed upon EGTA-induced junction splitting. Immunoelectron microscopy with various cadherin-specific antibodies revealed vesicle-associated labeling, confirming the derivation of these plaque-associated vesicles from the ZA. As the desmosome-specific cadherin, desmoglein, is recovered in another type of junction-derived vesicle, which is characterized by its association with a desmoplakin-plaque, we conclude that the membrane domains of both kinds of junction are endocytosed during Ca2+ depletion but stay in different vesicle populations, emphasizing the selective interaction of the specific cadherins with their respective plaque and filament partners.

MeSH terms

  • Actins / metabolism
  • Animals
  • Cadherins / metabolism*
  • Calcium / physiology*
  • Cattle
  • Cell Adhesion
  • Cell Membrane / metabolism
  • Cells, Cultured
  • Desmosomes / metabolism
  • Desmosomes / ultrastructure
  • Endocytosis
  • Fluorescent Antibody Technique
  • Immunoenzyme Techniques
  • In Vitro Techniques
  • Intercellular Junctions / metabolism*
  • Intercellular Junctions / ultrastructure
  • Intracellular Membranes / metabolism
  • Kidney / cytology
  • Microscopy, Electron

Substances

  • Actins
  • Cadherins
  • Calcium