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Results for “Intercellular Junctions”

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PubMed2006

The antiarrhythmic peptide rotigaptide (ZP123) increases gap junction intercellular communication in cardiac myocytes and HeLa cells expressing connexin 43.

We investigated the effects of rotigaptide (ZP123), a stable hexapeptide with antiarrhythmic properties, on gap junction mediated intercellular communication in contracting rat neonatal cardiac myocytes, HL-1 cells derived from cardiac atrium and in HeLa cells transfected with cDNA encoding Cx43-GFP, Cx32-GFP, Cx26-GFP, wild-type Cx43 or wild-type Cx26. Intercellular communication was monitored before and after treatment with rotigaptide following microinjection of small fluorescent dyes (MW<1 kDa). The communication-modifying effect of rotigaptide was confined to cells expressing Cx43 since the peptide had no effect on dye transfer in HeLa cells expressing Cx32-GFP, Cx26-GFP or wild-type Cx26. In contrast, HeLa cells expressing Cx43-GFP exposed to 50 nM rotigaptide for 5 h showed a 40% increase in gap junction mediated communication. Rotigaptide (50 nM) increased intercellular dye transfer in myocytes and atrial HL-1 cells, where Cx43 is the dominant connexin. However, it caused no change in cell beating rates of cardiac myocytes. Western blot analysis showed that rotigaptide did not modify the overall level of Cx43 expression and changes in the phosphorylation status of the protein were not observed.We conclude that the effects of rotigaptide were confined to cells expressing Cx43.

Animals↗
PubMed2003

Microinjection of actin antibodies impaired gap junctional intercellular communication in lens epithelial cells in vitro.

PURPOSE: The aim of this study was to check the importance of cytoskeletal actin for gap junction mediated intercellular communication (GJIC) in cultured lens epithelial cells (LEC). METHODS: Bovine LEC were cultured until confluency on cover-slides of a collocate-system. In order to study the cytoskeletal influence on cell communication microcinjection of gap junction permeable neurobiotin into a single cell was preceded by microinjection of actin antibodies. Confocal laser scanning microscopy of specimens treated with actin antibodies and/or subsequent phalloidin labelling, and electron microscopy, were applied to check for cytoskeleton cell membrane links. Specificity of actin antibodies was proved by immoblotting techniques. RESULTS: Immunohistochemistry and phalloidin-rhodamine staining displayed bundles of actin-filaments extending through the entire LEC. Quantitative analysis of GJIC showed intensive dye-spreading of neurobiotin between adjacent LEC. Injection of actin antibodies thirty minutes prior to microinjection of neurobiotin significantly reduced GJIC. Microinjection of irrelevant antibodies had no effect on GJIC. CONCLUSION: Integrity of the actin-cytoskeleton is fundamental for unimpaired GJIC in LEC.

Actins↗
PubMed1988

Lactic acid inhibition of gap junctional intercellular communication in in vitro astrocytes as measured by fluorescence recovery after laser photobleaching.

Lactic acid can permeate plasma membranes, causing intracellular acidosis. Gap junctions are sensitive to pHi and can be reversibly uncoupled by weak acids. In this study, dye coupling between in vitro astrocytes, presumably mediated by gap junctions, was measured in the absence and presence of lactic acid. Fluorescence recovery after laser photobleaching (gap-FRAP analysis) was used to measure dye coupling. Astrocytes bathed in Eagle's minimum essential medium (EMEM) with lactic acid, pHo 5.5-6, showed no difference in their dye coupling (mean recovery of fluorescence 30%) when compared to control astrocytes (mean recovery of fluorescence 26%). However, 24 mM lactic acid in EMEM, pHo 4.5, decreased dye coupling (mean recovery of fluorescence 2.0%). This effect occurred within 5 min of treatment. When lactic acid-EMEM, pH 4.5, was removed from astrocytes after 30 min and the cells were incubated in EMEM for 24 hr, decreased coupling was not reversed (mean recovery 4.0%). When lactic acid-treated astrocytes were incubated in EMEM for 48 hr, the mean recovery of fluorescence increased to 15% (i.e., 42% of the recovery seen in controls). These observations suggest that brief exposure to high concentrations of lactic acid can have immediate and long-lasting effects on glial gap junctional communication. Under pathological circumstances, such a sequence could be initiated, and this might impair astrocytic control of the central nervous system microenvironment mediated by spatial buffering.

Animals↗
PubMed1980

Intercellular junctions in nerve-free hydra.

Epithelial cells of nerve-free hydra contain septate and gap junctions. In thin sections the gap junctions are characterized by a gap of 3-4 nm. Freeze-fracture demonstrates the presence of septate junctions and two further types of structures: (i) the "E-type" or "inverted" gap junctions with particles in an "enplaque conformation appearing as a raised plateau on the E-face or as a depression on the P-face; (ii) structures morphologically similar to gap junctions in rat liver, containing particles on the P-face and corresponding pits on the E-face, both having hexagonal packing with a lattice constant of 8 nm. We propose that these structures are also gap junctions.

Animals↗