Decreased gap junctional communication in neurobiotin microinjected lens epithelial cells after taxol treatment.
The aim of the study was to examine gap-junction-mediated intercellular communication after experimentally induced aggregations of microtubules in cultured bovine lens epithelial cells. Intercellular communication between lens cells appears to be crucial for normal lens homeostasis. However, investigations on the maintenance of direct ion and metabolite exchange via gap junctions and its quantified dependency of cytoskeletal microtubules have not been available under conditions leading to bundling of microtubules. Thus, metabolic coupling of neighboring lens epithelial cells was quantified following microinjections of neurobiotin into single cells under various conditions. In controls, intensive gap-junction-mediated intercellular communication could be documented by dye-spreading of microinjected neurobiotin. In contrast, taxol treatment for 1-3 days impaired, but did not completely block gap-junction-mediated intercellular communication. After depletion of taxol, a complete recovery of intercellular communication was achieved. In addition, confocal laser scanning microscopy and rapid-freeze deep-etch electron microscopy revealed a displacement of actin-filaments from the perinuclear cytoplasm, accompanied by an abnormal aggregation of microtubules after taxol treatment, including impeded translocation of connexin 43 from the cytoplasm into the plasma membrane. Incubation of cells with nocodazole destroyed the microtubule network, accompanied by a clear reduction of plasma-membrane-integrated connexin 43 and significant impairment of dye spreading. Thus, in lens epithelial cells intercellular communication at gap junctions made by connexin 43 depends on the integrity of the microtubule network through the translocation of connexins to the plasma membrane.
Giessmann
Daniel
D
Institut für Anatomie, Abteilung für Cytologie, Medizinische Fakultät, Ruhr-Universität Bochum, 44780 Bochum, Germany.
Theiss
Carsten
C
Breipohl
Winrich
W
Meller
Karl
K
D008841:Actin Cytoskeleton / Q000187:drug effects / Q000502:physiology / Q000648:ultrastructure; D000818:Animals; D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology; D001710:Biotin / Q000031:analogs & derivatives; D002417:Cattle; D002450:Cell Communication / Q000187:drug effects / Q000502:physiology*; D002462:Cell Membrane / Q000502:physiology / Q000648:ultrastructure; D018031:Connexin 43 / Q000378:metabolism; D015536:Down-Regulation / Q000187:drug effects / Q000502:physiology; D004847:Epithelial Cells / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D005613:Freeze Etching; D017629:Gap Junctions / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D007908:Lens, Crystalline / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D008845:Microinjections; D018613:Microscopy, Confocal; D046529:Microscopy, Electron, Transmission; D008870:Microtubules / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D017239:Paclitaxel / Q000494:pharmacology; D021381:Protein Transport / Q000187:drug effects / Q000502:physiology
D000972:Antineoplastic Agents, Phytogenic; D018031:Connexin 43; C070614:neurobiotin; D001710:Biotin; D017239:Paclitaxel