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At least 199 records · Page 11Linked to original sources
PubMed1991

Regulation of connexin 43-mediated gap junctional intercellular communication by Ca2+ in mouse epidermal cells is controlled by E-cadherin.

Gap junctional intercellular communication (GJIC) of cultured mouse epidermal cells is mediated by a gap junction protein, connexin 43, and is dependent on the calcium concentration in the medium, with higher GJIC in a high-calcium (1.2 mM) medium. In several mouse epidermal cell lines, we found a good correlation between the level of GJIC and that of immunohistochemical staining of E-cadherin, a calcium-dependent cell adhesion molecule, at cell-cell contact areas. The variant cell line P3/22 showed both low GJIC and E-cadherin protein expression in low- and high-Ca2+ media. P3/22 cells showed very low E-cadherin mRNA expression. To test directly whether E-cadherin is involved in the Ca(2+)-dependent regulation of GJIC, we transfected the E-cadherin expression vector into P3/22 cells and obtained several stable clones which expressed high levels of E-cadherin mRNA. All transfectants expressed E-cadherin molecules at cell-cell contact areas in a calcium-dependent manner. GJIC was also observed in these transfectants and was calcium dependent. These results suggest that Ca(2+)-dependent regulation of GJIC in mouse epidermal cells is directly controlled by a calcium-dependent cell adhesion molecule, E-cadherin. Furthermore, several lines of evidence suggest that GJIC control by E-cadherin involves posttranslational regulation (assembly and/or function) of the gap junction protein connexin 43.

Animals↗
PubMed2005

Astaxanthin diminishes gap junctional intercellular communication in primary human fibroblasts.

Astaxanthin is a carotenoid found in plants and algae; it provides the color of marine seafood such as salmon, lobster, or shrimp. Carotenoids are antioxidants and exhibit other biological functions, including effects on gap junctional communication important for homeostasis, growth control, and development of cells. Cancer cells have an impaired gap junctional intercellular communication. The objective of the present study was to determine the effects of astaxanthin and canthaxanthin on gap junctional intercellular communication in vitro. Primary human skin fibroblasts were exposed to carotenoids from 0.001 to 10 micromol/L, and gap junctional communication was measured with a dye transfer assay. After incubation with canthaxanthin for 24 and 72 h, intercellular communication increased, whereas it was strongly diminished by astaxanthin at levels > 0.1 micromol/L. Inhibition was reversed when astaxanthin was withdrawn. Western blot analysis showed that after exposure to canthaxanthin, the amount of the gap junction protein connexin43 was increased. Incubation with astaxanthin led to a change in the phosphorylation pattern of connexin43, shifting from higher to lower phosphorylation states. We suggest that astaxanthin affects channel function by changing the phosphorylation pattern of connexin43.

Anticarcinogenic Agents↗
PubMed1991

Incorporation of n-3 fatty acids into WB-F344 cell phospholipids inhibits gap junctional intercellular communication.

In this investigation, we demonstrate that rat liver epithelial (WB-F344) cells grown in medium supplemented with n-3 fatty acids (FA) results in the inhibition of gap junctional intercellular communication (GJIC). Cells incubated for 48 hr in medium containing 50 microM alpha-linolenate (18:3n-3) resulted in a 60% inhibition of GJIC, compared to control cells, while treatment with gamma-linolenate (18:3n-6) had no effect. Supplementation with octadecatetraenoate (18:4n-3), eicosapentaenoate (20:5n-3), and docosahexaenoate (22:6n-3), inhibited GJIC by 42%, 28%, and 18%, respectively. Incubation with each of the n-3 FA markedly increased the total n-3 FA content of cellular phospholipids (PL). Growing cells in medium containing 50 microM arachidonate (20:4n-6) plus 50 microM 18:3n-3 partially attenuated the inhibition of GJIC induced by 18:3n-3. The mechanism by which n-3 FA inhibit GJIC remains to be determined.

Animals↗
PubMed1978

Ruthenium red-positive surface layer, extracellular filamentous material and intercellular junctions in hybrids between tumour and normal cells: abundant gap junctions correlate with density-dependent inhibition of growth.

The cell surface and intercellular junctions of transformed and non-transformed hybrid cells, obtained from fusion of murine mammary adenocarcinoma cells (TA3B) and normal rat embryofibroblasts (REF), were compared with those of the parental cells, using ruthenium red (RR) staining of cells fixed in situ. An RR-positive layer of variable thickness was found on the surface of all cell types. Measurements of the thickness of this layer on the free surface of the cell cultures deomonstrated a significant difference between transformed and non-transformed cells. The thickness distribution of the RR layer was similar on the surface of REF and non-transformed hybrid cells, but there was significant variation among all the transformed cell lines. Extracellular filamentous RR-positive material, usually in direct contact with the cell surface, was present in confluent cultures of REF and non-transformed hybrid cells, but was absent in the transformed cell lines. Gap junctions were few in both parental cell lines and rare or absent in transformed hybrids; a large increase in number and size of gap junctions was found in non-transformed hybrids. Abundance of long gap junctions was correlated with density-dependent inhibition of growth, since non-transformed hybrids grew in single layers whereas both normal and tumour parental cell types, and transformed hybrids grew in multilayers. Tight junctions were frequently encountered in TA3B and transformed hybrid cells but were not seen in REF cells and only occasionally seen in non-transformed hybrids. Intermediate-type junctions occurred in all cells, but desmosomes were found only rarely in TA3B cells and never in the other cell types.

Adenocarcinoma↗
PubMed1979

[Electron microscopic study of the intercellular junctions during the ciliary epithelial differentiation of the eye of the common frog].

Intercellular junctions in the eye ciliary epithelium were studied in Rana temporaria by means of transmission electron microscopy beginning from the stage of appearance of the light sensitivity in the larval eye and until the completion of metamorphosis. In the ciliary epithelium inner layer the apical parts of adjacent cells are tied by contacts forming the junction complex already at a very early developmental stage. The most apical position in this complex is occupied by the focal junction which appears to be an early stage of zonula occludens; this complex includes also zonula adherens and macula adherens which may follow in any succession focal junction or zonula occludens. No definite order was found in the localization of cell contacts between the outer and inner layers of ciliary epithelium, as well as between the side surfaces of the cells within each layer. Contacts were found everywhere termed as "lengthy" which may be considered as gap junctions. Regional differences were found in the ultrastructure of the ciliary epithelium cells with respect to unequal distribution of functional loads.

Animals↗
PubMed1999

Glucocorticoids regulate transendothelial fluid flow resistance and formation of intercellular junctions.

The regulation of transendothelial fluid flow by glucocorticoids was studied in vitro with use of human endothelial cells cultured from Schlemm's canal (SCE) and the trabecular meshwork (TM) in conjunction with computer-linked flowmeters. After 2-7 wk of 500 nM dexamethasone (Dex) treatment, the following physiological, morphometric, and biochemical alterations were observed: a 3- to 5-fold increase in fluid flow resistance, a 2-fold increase in the representation of tight junctions, a 10- to 30-fold reduction in the mean area occupied by interendothelial "gaps" or preferential flow channels, and a 3- to 5-fold increase in the expression of the junction-associated protein ZO-1. The more resistive SCE cells expressed two isoforms of ZO-1; TM cells expressed only one. To investigate the role of ZO-1 in the aforementioned Dex effects, its expression was inhibited using antisense phosphorothioate oligonucleotides, and the response was compared with that observed with the use of sense and nonsense phosphorothioate oligonucleotides. Inhibition of ZO-1 expression abolished the Dex-induced increase in resistance and the accompanying alterations in cell junctions and gaps. These results support the hypothesis that intercellular junctions are necessary for the development and maintenance of transendothelial flow resistance in cultured SCE and TM cells and are likely involved in the mechanism of increased resistance associated with glucocorticoid exposure.

Body Fluids↗
PubMed1994

The expression, phosphorylation, and localization of connexin 43 and gap-junctional intercellular communication during the establishment of a synchronized contraction of cultured neonatal rat cardiac myocytes.

We analyzed the expression, phosphorylation, and localization of the major cardiac gap-junction protein connexin 43 (Cx43) during the establishment of a synchronized contraction in confluent monolayers of primary cultured neonatal rat cardiac myocytes, combined with a functional assay of gap junctions by the microinjection-dye transfer method. Monitoring of the beating rate and synchronization by Fotonic Sensor showed that at Day 1 of culture cardiac myocytes contracted spontaneously but irregularly, that the contractile rate increased with culture time, and that a synchronized contraction was gradually formed. At Day 7, the confluent cells exhibited synchronous contraction with a relatively constant rate (125 +/- 20 beats/min). Cardiac myocytes expressed a large amount of Cx43 mRNA even at Day 1 and maintained the expression until at least Day 7. Immunofluorescence of Cx43 showed that the localization of Cx43-positive spots was mostly restricted to cell-cell contacts between myocytes and that few Cx43-positive spots were present between myocytes and fibroblasts or between fibroblasts. The amount of Cx43 protein, the proportion of phosphorylated forms to the nonphosphorylated one, and the number and total area of Cx43-positive spots increased with culture time. Gap-junctional intercellular communication measured by dye transfer assay was also increased with culture time and correlated well with the number and total area of Cx43-positive spots. Our systematic study suggests that a concerted action of the expression, phosphorylation, and localization of Cx43 and gap-junctional intercellular communication plays a major role in the reestablishment of synchronous beating of cultured neonatal rat cardiac myocytes.

Animals↗
PubMed1991

Regulation of gap-junctional intercellular communication in transformation-sensitive and transformation-resistant BALB/c 3T3 cell variants.

BALB/c 3T3 A31-1-13 cells are highly susceptible to chemical-induced cell transformation and their gap-junctional intercellular communication (GJIC) is decreased when these cells become confluent. On the other hand, A31-1-1 cells do not show such a change in GJIC and are more resistant to chemical induction of transformation. In order to see which phenotypes are dominant, cells of these two types were hybridized and the hybrids were analyzed for their phenotypes for GJIC and induction of cell transformation. These two cell lines were tagged with neor gene or hygromycin-resistance gene respectively, and their hybrids were selected in medium containing G418 and hygromycin. Six independently isolated clones were characterized and all showed a loss of intercellular communication at confluence, suggesting that the phenotype of transformation-sensitive cell line A31-1-13 was dominant. However, when these hybrid cells were exposed to 3-methylcholanthrene, no transformed foci were produced, suggesting that the transformation-resistant phenotype is dominant. These results suggest that the regulation of GJIC and the susceptibility to chemical induction of transformation are genetically separate traits, and indirectly suggest that the loss of GJIC alone cannot explain the high susceptibility of A31-1-13 cells to induction of transformation.

3T3 Cells↗
PubMed2006

[Effect of PM2.5 collected during the dust and non-dust periods on the viability and gap junctional intercellular communication in human lung fibroblasts].

OBJECTIVE: To investigate the effects of PM2.5 collected during the dust and non-dust periods on the viability and gap junctional intercellular communication (GJIC) in human lung fibroblasts. METHODS: Human lung fibroblasts were treated with PM2.5 suspension and its organic and inorganic extracts at various concentrations for 24 h. The cellular viability was measured with MTT methods, and the GJIC between human lung fibroblasts was detected by the scrape loading dye transfer assay. RESULTS: PM2.5 suspension from both sources and the inorganic extracts of dust PM2.5 significantly decreased the viability of human lung fibroblast in a dose-dependent manner. Compared with other preparations, the dust PM2.5 suspension had the highest effect. Gap junctional intercellular communication between human lung fibroblasts was significantly inhibited by the different composition of PM2.5 from both sources in a dose-dependent manner. The inhibitory effects on GJIC were in the order of organic extract of PM2.5 > suspension > inorganic extract. CONCLUSION: Composition and source of PM2.5 are important factors which influnce the toxic effects on cells. The composition of PM2.5 from both sources can inhibit GJIC, suggesting decreasing GJIC may be related to the biological mechanisms of toxicity caused by PM2.5.

Air Pollutants↗
PubMed1993

Enhancement of gap junctional intercellular communication in tumor promoter-treated cells by components of green tea.

Green tea (Camellia sinensis) has been reported to inhibit tumor promotion in vivo and in vitro. Many tumor promoters inhibit gap junctional intercellular communication (GJIC) which may be an important mechanism of promotion. In the present study, we hypothesized that green tea would enhance GJIC in promoter-treated cells. An aqueous extract of green tea (GTE) and several of its constituents were tested for their effects on GJIC in p,p'-dichlorodiphenyltrichloroethane (DDT)-, 12-O-tetradecanoylphorbol-13-acetate (TPA)- and dieldrin-treated WB-F344 rat liver epithelial cells. All three promoters inhibited GJIC in a dose-responsive manner at non-cytolethal concentrations. (GTE (10-80 gamma/ml) enhanced GJIC 20-80% in promoter-treated cells. (-)-Epigallocatechin gallate and (-)-epicatechin gallate also enhanced GJIC in DDT-treated cells, but no effects were seen with (+)-catechin, (-)-epicatechin, (-)-epigallocatechin, caffeine, or theobromine. These data suggest GTE may inhibit tumor promotion by enhancing GJIC and that the most active components are the catechin gallates.

Animals↗
PubMed1996

Inhibition of gap junctional intercellular communication in heptachlor- and heptachlor epoxide-treated normal human breast epithelial cells.

Based on the concern of organochlorides in the environment and in human tissue, this study was designed to determine whether various noncytotoxic levels of heptachlor and heptachlor epoxide could inhibit, reversibly, gap junctional intercellular communication in human breast epithelial cells (HBEC). Cytotoxicity and gap junctional intercellular communication (GJIC) were evaluated by lactate dehydrogenase assay and fluorescence redistribution after photobleaching analysis, respectively. Both heptachlor and heptachlor epoxide were noncytotoxic up to 10 microg/ml. At this concentration, heptachlor and heptachlor epoxide inhibited GJIC of normal human breast epithelial cells after 1 h treatment. Within a 24 h treatment with heptachlor and heptachlor epoxide at 10 microg/ml, recovery of GJIC had not returned. GJIC completely recovered after a 12 h treatment of 1 microg/ml heptachlor epoxide, but it did not recover after a 24 h treatment of 1 microg/ml heptachlor. RT-PCR and Western blots were analyzed to determine whether the heptachlor or heptachlor epoxide might have altered the steady-state levels of gap junction mRNA and/or connexin protein levels or phosphorylation state. No significant difference in the level of connexin 43 (Cx43) message between control and heptachlor-treated cells was observed. Western blot analyses showed hypophosphorylation patterns in cells treated with 10 microg/ml heptachlor and heptachlor epoxide for 1 h with no recovery within 24 h. Immunostaining of Cx43 protein in normal HBEC indicated that heptachlor and heptachlor epoxide caused a loss of Cx43 from the cell membranes at noncytotoxic dose levels. Taken together, these results suggest that heptachlor and heptachlor epoxide can alter GJIC at the post-translational level, and that, under the conditions of exceeding a threshold concentration in the breast tissue containing 'initiated' cells for a long time and not being counteracted by anti-tumor-promoting chemicals, they could act as breast tumor promoters.

Base Sequence↗
PubMed1985

Phosphotyrosine-containing proteins are concentrated in focal adhesions and intercellular junctions in normal cells.

We have used a high-affinity polyclonal antibody directed against phosphotyrosine (P-Tyr) to localize P-Tyr-containing proteins in normal and transformed cells in culture by immunofluorescence microscopy experiments. The distribution of the proteins with modified tyrosine was compared with that of F-actin in these cells. Cells infected with Abelson murine leukemia virus were found to contain elevated levels of P-Tyr, as expected. Various permanent lines of fibroblastic and epithelial cells exhibited lower, but easily detectable, levels of P-Tyr. The P-Tyr in fibroblasts was concentrated at the focal contacts at the termini of actin-containing microfilament bundles and, in the epithelial cells examined, at the intercellular junctions. Early passages of primary cultures of chicken embryo fibroblasts and chicken embryo heart cells also showed detectable levels of P-Tyr in focal contacts and cell-cell junctions. However, P-Tyr was not detectable in later passages of chicken embryo fibroblasts. The concentration of P-Tyr-containing proteins in intercellular junctions in normal cells suggests that these are sites of significant biochemical regulatory activities which may be important in the control of normal cell adhesivity, motility, and shape.

Actin Cytoskeleton↗
PubMed2000

Quantitative determination of gap junction intercellular communication by scrape loading and image analysis.

Gap junction intercellular communication (GJIC) consists of intercellular exchange of low molecular weight molecules. Chemically induced alterations of this communication have been suggested to result in abnormal cell growth and tumour promotion. Several in vitro assays have been developed to determine the effect of chemicals on gap junction communication in cultured cells. The scrape loading dye transfer technique is based on studying the transfer of the fluorescent dye Lucifer Yellow in cells where the dye is loaded through a cut in the cell monolayer. This technique is rapid and relatively uncomplicated, but has only been used to qualitatively demonstrate communication, due to lack of an appropriate method for quantification of the dye spreading. We show here that analysis of digital fluorescence images of cells scrape loaded with Lucifer Yellow can be used for quantitative determination of GJIC. We have analysed the images both by means of distance of diffusion of the dye in the cell monolayer, as well as by area of dye-coupled cells. The results are consistent with that obtained using microinjection of Lucifer Yellow and the method offers a simple way for quantitative determination of GJIC.

Animals↗
PubMed2004

Paracrine effect of TGF-beta1 on downregulation of gap junctional intercellular communication between human dermal fibroblasts.

Disruption of gap junctional intercellular communication (GJIC) is associated with tumor progression during multistage carcinogenesis. A coordinated interaction of epithelial tumor cells with the stromal environment via growth factors is a prerequisite for tumor invasion. Here, the involvement of growth factors in downregulation of homologous GJIC of dermal fibroblasts, used as model for stromal cells, was examined. Tumor cell derived transforming growth factor-beta1 (TGF-beta1), having oncogenic activities at late stages of carcinogenesis, was identified as being responsible for downregulation of GJIC via an increase in the level of reactive oxygen species in stromal fibroblasts. Lowering the level of reactive oxygen species by antioxidants, such as the cell-permeable N-acetyl-L-cysteine, prevented TGF-beta1-mediated downregulation of intercellular communication between confluent fibroblasts.

Cell Communication↗
PubMed2002

Gap junction intercellular communication propagates cell death in cancerous cells.

Gap junction intercellular communication (GJIC) or cell coupling has an important function in maintaining tissue homeostasis and is thus a critical factor in the life and death balance of cells. While the role of GJIC in cell growth regulation has been much studied, its involvement in apoptosis remains unclear. In this study we elucidated the possibility that cell death is propagated via gap junctions, employing the rat bladder carcinoma cell line BC31. BC31 cells proliferate quickly, are tumorigenic, and are well-coupled via gap junctions that contain the gap junction protein Connexin43 (Cx43). In addition, these cells are predisposed to spontaneous death by apoptosis, particularly upon achieving confluency. We found that many dying BC31 cells express Cx43 just as their non-apoptotic counterparts do. Furthermore, Cx43 in apoptotic cells could be functionally competent, supporting coupling of these cells with their non-apoptotic neighbors, and as a result, clusters of coordinately dying cells were observed. The role of Cx43 and GJIC in propagating cell death was shown by analysing clones of BC31 cells expressing a mutant of Cx43 that is a dominant negative inhibitor of GJIC, and by using beta-glycyrrhetinic acid to inhibit intrinsic cell coupling in BC31 cells: in both cases the formation of clusters of dying cells was abrogated, and the intensity of cell death was considerably decreased. These results suggest that GJIC spreads cell-killing signals initially generated by a single cell that spontaneously initiates apoptosis, into healthy surrounding cells, thus increasing the level of cell death. Treatment of BC31 cells with the sleep-inducing lipid Oleamide, which selectively restricts gap junction permeability to Ca(2+) ions, did not abrogate coordinated cell death by clusters, indicating that Ca(2+) ions are the most probable cell-killing signals spread through gap junctions.

Animals↗
PubMed1988

Treponema pallidum invades intercellular junctions of endothelial cell monolayers.

The pathogenesis of syphilis reflects invasive properties of Treponema pallidum, but the actual mode of tissue invasion is unknown. We have found two in vitro parallels of treponemal invasiveness. We tested whether motile T. pallidum could invade host cells by determining the fate of radiolabeled motile organisms added to a HeLa cell monolayer; 26% of treponemes associated with the monolayer in a trypsin-resistant niche, presumably between the monolayer and the surface to which it adhered, but did not attain intracellularity. Attachment of T. pallidum to cultured human and rabbit aortic and human umbilical vein endothelial cells was 2-fold greater than to HeLa cells. We added T. pallidum to aortic endothelial cells grown on membrane filters under conditions in which tight intercellular junctions had formed. T. pallidum was able to pass through the endothelial cell monolayers without altering tight junctions, as measured by electrical resistance. In contrast, heat-killed T. pallidum and the nonpathogen Treponema phagedenis biotype Reiter failed to penetrate the monolayer. Transmission electron micrographs of sections of the monolayer showed T. pallidum in intercellular junctions. Our in vitro observations suggest that these highly motile spirochetes may leave the circulation by invading the junctions between endothelial cells.

Animals↗
PubMed1996

The use of initiated cells as a test system for the detection of inhibitors of gap junctional intercellular communication.

The effects of five non-mutagenic carcinogens--Aroclor 1260, benzoyl peroxide (BP), phenobarbital (PB), 12-O-tetradecanoyl-phorbol-13-acetate (TPA) and 1,1'-(2,2,2-trichloroethylidene)bis[4-chlorobenzene] (DDT)--on gap junctional intercellular communication (GJIC) were tested in a cell line consisting of initiated cells (3PC). Four agents suspected of tumor promotion activity--o-anisidine, clofibrate, L-ethionone and d-limonene--were also tested for their effects on GJIC. Finally sodium fluoride (NaF), whose carcinogenic property is still unclear, was tested for its effects on GJIC in the 3PC cell line. Four of the five selected tumor promoters (Aroclor 1260, BP, DDT and TPA) decreased GJIC between these initiated epidermal cells. The four non-mutagenic carcinogens with tumor-promoting activity in vivo (o-anisidine, clofibrate, L-ethionine and d-limonene) all inhibited GJIC, whereas NaF had no effect. Seven compounds (o-anisidine, Aroclor 1260, BP, DDT, L-ethionine, d-limonene and TPA) had a dose-dependent as well as time-dependent inhibitory effect on GJIC. Under the experimental conditions used, clofibrate showed only a dose-related inhibition of GJIC. PB showed no inhibitory effect on GJIC in the 3PC cell line. In order to determine the role of biotransformation in the tumor-promoting activity of PB, its effect on GJIC was also examined in the presence of an Aroclor 1254-induced rat liver homogenate (S9 mix) and in the hepatoma cell line HepG2. In the presence of rat liver homogenate PB decreased GJIC in the 3PC cell line, whereas in the HepG2 cells PB showed a time- and dose-dependent inhibitory effect. To study the potential differences in susceptibility of cells representing different stages in the process of tumor formation, the effect of the selected tumor promoters on GJIC was also investigated in primary mouse keratinocytes and in a mouse skin carcinoma-derived cell line (CA3/7). Primary keratinocytes were sometimes more (BP and clofibrate) and sometimes less sensitive (ethionine and limonene) for inhibitory effects on GJIC compared to the effects in the cell line 3PC. Except for TPA and anisidin, GJIC between the CA3/7 cells was less affected by the selected agents compared to the 3PC cell line. These results show that, during the process of tumor formation the susceptibility of cells to inhibition of GJIC by tumor promoters is variable. Overall the CA3/7 cells are less sensitive compared to 3PC cells. The susceptibility of primary keratinocytes is variable compared to 3PC cells, depending on the agent used. These results also show that GJIC is a valid parameter for testing the tumor-promoting activity of compounds. Finally, this study demonstrates that mouse keratinocyte cell lines could serve as an in vitro model for the detection of non-mutagenic carcinogens with diverse target organs in vivo. For this use the cell line consisting of initiated cells (3PC) is more sensitive than the carcinoma-derived cell line CA3/7.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1997

Altered gap junctional intercellular communication in neoplastic rat esophageal epithelial cells.

Gap junctional intercellular communication (GJIC) is reduced in many neoplastic cells, but few data exist for esophageal neoplasms. GJIC was examined by fluorescent dye microinjection in two nontumorigenic and two highly tumorigenic rat esophageal epithelial cell lines. All lines expressed high levels of dye coupling in homologous cell culture. In cocultures of nontumorigenic and tumorigenic cells, however, only one of six cell combinations displayed significant heterologous GJIC. Northern, Western, and immunohistochemical analyses indicated that all four cell lines expressed comparable levels of connexin43 (Cx43), but not connexin32 or connexin26, and formed Cx43-containing gap junction plaques at cell-cell interfaces. Immunostaining of rat esophageal frozen sections demonstrated that esophageal epithelial cells expressed Cx43 in vivo. In normal epithelium, the highest expression was seen in the basal cells and little suprabasal staining was evident. In preneoplastic and neoplastic lesions of the esophageal epithelium which were induced by treating rats with N-nitrosomethylbenzylamine, Cx43 staining of the basal layer was also seen but appeared to be more diffuse compared to normal epithelium. In addition, suprabasal Cx43 staining was apparent in dysplastic and papillomatous lesions. These results indicate that Cx43 is expressed in normal and neoplastic rat esophageal cells and that the cells exhibit extensive homologous GJIC, but little heterologous GJIC. This lack of heterologous GJIC may be due to differences in cell adhesion proteins or other factors.

Animals↗