A freeze-fracture study of intercellular junctions between various kinds of epithelial cells surrounding common endolymphatic space in the hearing organ of the chick

1980 ◽  
Vol 196 (2) ◽  
pp. 129-143 ◽  
Author(s):  
Nobutaka Hirokawa
Keyword(s):  
Epithelial Cells ◽  
Freeze Fracture ◽  
Intercellular Junctions ◽  
Hearing Organ ◽  
Fracture Study ◽  
Endolymphatic Space

Cell junctions in the excitable epithelium of bioluminescent scales on a polynoid worm: a freeze-fracture and electrophysiological study

1980 ◽  
Vol 41 (1) ◽  
pp. 341-368
Author(s):  
A. Bilbaut
Keyword(s):  
Epithelial Cells ◽  
Gap Junctions ◽  
Action Potentials ◽  
Electrophysiological Study ◽  
Freeze Fracture ◽  
Intercellular Junctions ◽  
Cell Junctions ◽  
Functional Roles ◽  
Electrophysiological Properties ◽  
Current Passage

The bioluminescent scales of the polynoid worm Acholoe are covered by a dorsal and ventral monolayer of epithelium. The luminous activity is intracellular and arises from the ventral epithelial cells, which are modified as photocytes. Photogenic and non-photogenic epithelial cells have been examined with regard to intercellular junctions and electrophysiological properties. Desmosomes, septate and gap junctions are described between all the epithelial cells. Lanthanum impregnation and freeze-fracture reveal that the septate junctions belong to the pleated-type found in molluscs, arthropods and other annelid tissues. Freeze-fractured gap junctions show polygonal arrays of membrane particles on the P face and complementary pits on the E face. Gap junctions are of the P type as reported in vertebrate, mollusc and some annelid tissues. Intracellular current passage also induces propagated non-overshooting action potentials in all the epithelial cells; in photocytes, an increase of injected current elicits another response which is a propagated 2-component overshooting action potential correlated with luminous activity. This study shows the coexistence of septate and gap junctions in a conducting and excitable invertebrate epithelium. The results are discussed in relation to the functional roles of intercellular junctions in invertebrate epithelia. It is concluded that the gap junctions found in this excitable epithelium represent the structural sites of the cell-to-cell propagation of action potentials.

scholarly journals Glycoprotein E of Varicella-Zoster Virus Enhances Cell-Cell Contact in Polarized Epithelial Cells

2000 ◽  
Vol 74 (23) ◽  
pp. 11377-11387 ◽  
Author(s):  
Chengjun Mo ◽  
Eveline E. Schneeberger ◽  
Ann M. Arvin
Keyword(s):  
Epithelial Cells ◽  
Varicella Zoster Virus ◽  
Mdck Cells ◽  
Freeze Fracture ◽  
Intercellular Junctions ◽  
Cell Contact ◽  
Varicella Zoster ◽  
Actin Organization ◽  
Polarized Epithelial Cells ◽  
Cell Cell

ABSTRACT Varicella-zoster virus (VZV) infection involves the cell-cell spread of virions, but how viral proteins interact with the host cell membranes that comprise intercellular junctions is not known. Madin-Darby canine kidney (MDCK) cells were constructed to express the glycoproteins gE, gI, or gE/gI constitutively and were used to examine the effects of these VZV glycoproteins in polarized epithelial cells. At low cell density, VZV gE induced partial tight junction (TJ) formation under low-calcium conditions, whether expressed alone or with gI. Although most VZV gE was intracellular, gE was also shown to colocalize with the TJ protein ZO-1 with or without concomitant expression of gI. Freeze fracture electron microscopy revealed normal TJ strand morphology in gE-expressing MDCK cells. Functionally, the expression of gE was associated with a marked acceleration in the establishment of maximum transepithelial electrical resistance (TER) in MDCK-gE cells; MDCK-gI and MDCK-gE/gI cells exhibited a similar pattern of early TER compared to MDCK cells, although peak resistances were lower than those of gE alone. VZV gE expression altered F-actin organization and lipid distribution, but coexpression of gI modulated these effects. Two regions of the gE ectodomain, amino acids (aa) 278 to 355 and aa 467 to 498, although lacking Ca2+ binding motifs, exhibit similarities with corresponding regions of the cell adhesion molecules, E-cadherin and desmocollin. These observations suggest that VZV gE and gE/gI may contribute to viral pathogenesis by facilitating epithelial cell-cell contacts.

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