title: Myosin-1c regulates the dynamic stability of E-cadherin-based cell-cell contacts in polarized Madin-Darby canine kidney cells.
abstract: Cooperation between cadherins and the actin cytoskeleton controls the formation and maintenance of cell-cell adhesions in epithelia. We find that the molecular motor protein myosin-1c (Myo1c) regulates the dynamic stability of E-cadherin-based cell-cell contacts. In Myo1c-depleted Madin-Darby canine kidney cells, E-cadherin localization was dis-organized and lateral membranes appeared less vertical with convoluted edges versus control cells. In polarized monolayers, Myo1c-knockdown (KD) cells were more sensitive to reduced calcium concentration. Myo1c separated in the same plasma membrane fractions as E-cadherin, and Myo1c KD caused a significant reduction in the amount of E-cadherin recovered in one peak fraction. Expression of green fluorescent protein (GFP)-Myo1c mutants revealed that the phosphatidylinositol-4,5-bisphosphate-binding site is necessary for its localization to cell-cell adhesions, and fluorescence recovery after photobleaching assays with GFP-Myo1c mutants revealed that motor function was important for Myo1c dynamics at these sites. At 18°C, which inhibits vesicle recycling, Myo1c-KD cells accumulated more E-cadherin-positive vesicles in their cytoplasm, suggesting that Myo1c affects E-cadherin endocytosis. Studies with photoactivatable GFP-E-cadherin showed that Myo1c KD reduced the stability of E-cadherin at cell-cell adhesions. We conclude that Myo1c stabilizes E-cadherin at adherens junctions in polarized epithelial cells and that the motor function and ability of Myo1c to bind membrane are critical.
authors.affiliation: Department of Physiology and Biophysics, Boston University School of Medicine, Boston, MA 02118-2518.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Tokuo
authors.forename: Lynne M
authors.initials: LM
authors.lastname: Coluccio
mesh_terms: D000199:Actins / Q000378:metabolism; D022005:Adherens Junctions / Q000187:drug effects / Q000378:metabolism; D000818:Animals; D015820:Cadherins / Q000378:metabolism*; D002118:Calcium / Q000494:pharmacology; D002448:Cell Adhesion / Q000187:drug effects; D002450:Cell Communication / Q000187:drug effects; D002452:Cell Count; D002458:Cell Fractionation; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D016764:Cell Polarity / Q000187:drug effects; D048430:Cell Shape / Q000187:drug effects; D004285:Dogs; D004847:Epithelial Cells / Q000166:cytology* / Q000378:metabolism*; D055785:Gene Knockdown Techniques; D020868:Gene Silencing / Q000187:drug effects; D061985:Madin Darby Canine Kidney Cells; D009218:Myosins / Q000737:chemistry / Q000378:metabolism*; D010641:Phenotype; D055550:Protein Stability / Q000187:drug effects; D017434:Protein Structure, Tertiary; D021381:Protein Transport / Q000187:drug effects; D014283:Triiodobenzoic Acids / Q000494:pharmacology
chemical_list: D000199:Actins; D015820:Cadherins; D014283:Triiodobenzoic Acids; D009218:Myosins; C044834:iodixanol; D002118:Calcium