Gap junctions mediate direct communication between cells; however, toxicological cascade triggered by nonessential metals can abrogate cellular signaling mediated by gap junctions. Although cadmium (Cd) is known to induce apoptosis in organs and tissues, the mechanisms that underlie gap junction activity in Cd-induced apoptosis in BRL 3A rat liver cells has yet to be established. In this study, we showed that Cd treatment decreased the cell index (a measure of cellular electrical impedance) in BRL 3A cells. Mechanistically, we found that Cd exposure decreased expression of connexin 43 (Cx43), increased expression of p-Cx43 and elevated intracellular free Ca2+ concentration, corresponding to a decrease in gap junctional intercellular communication. Gap junction blockage pretreatment with 18β-glycyrrhizic acid (GA) promoted Cd-induced apoptosis, involving changes in expression of Bax, Bcl-2, caspase-3 and the mitochondrial transmembrane electrical potential (Δψm). Additionally, GA was found to enhance ERK and p38 activation during Cd-induced activation of mitogen-activated protein kinases, but had no significant effect on JNK activation. Our results indicated the apoptosis-related proteins and the ERK and p38 signaling pathways may participate in gap junction blockage promoting Cd-induced apoptosis in BRL 3A cells.
Animals ; Apoptosis/*drug effects ; Cadmium/*toxicity ; Calcium/metabolism ; Cell Communication/drug effects ; Connexin 43/genetics ; Enzyme Activation/drug effects ; Gap Junctions/*drug effects ; Gene Expression Regulation/drug effects ; Hepatocytes/cytology/*drug effects ; Rats ; Signal Transduction/drug effects

OBJECTIVETo investigate the effect of baicalein on the gap junction intercellular communication (GJIC) in the TM4 Sertoli cells of the mouse testis and its related mechanism.

METHODSWe measured the cytotoxicity of different concentrations of baicalein on the TM4 Sertoli cells in the mouse testis by MTT, detected the fluorescence transfer of the TM4 Sertoli cells by parachute assay, and determined the expression of the protein connexin 43 ( Cx43) in the baicalein-treated cells by Western blot and immunofluorescence assay.

RESULTSBaicalein produced no obvious cytotoxicity on the TM4 Sertoli cells at the concentration below 60 µmol/L but significantly increased their GJIC at 0-20 µmol/L (P < 0.01). Western blot and immunofluorescence assay showed that 0-20 µmol/L baicalein remarkably elevated the expression of Cx43 in the TM4 cells (P < 0.01) and on the membrane of the TM4 cells.

CONCLUSIONBaicalein at the concentration of 0-20 µmol/L can significantly enhance GJIC in mouse TM4 Sertoli cells by increasing the expression of the Cx43 protein.

Animals ; Cell Communication ; drug effects ; Connexin 43 ; metabolism ; Flavanones ; administration & dosage ; pharmacology ; Gap Junctions ; drug effects ; Male ; Mice ; Sertoli Cells ; drug effects ; metabolism ; ultrastructure

OBJECTIVETo investigate the effects of total flavonoids of Litsea Coreana (TFLC) on the gap junction (GJ) intercellular communication in TM3 testicular Leydig cells and whether TFLC can reduce the cytotoxicity of oxaliplatin (OHP) in vitro.

METHODSWe detected the effect of TFLC on the dye spread of the in vitro cultured TM3 cells by parachute assay, observed changes in the expression of connexin 43 (Cx43) total protein in the TFLC-treated TM3 cells by Western blot, and determined the effects of TFLC on the expression of Cx43 on the membrane of the TM3 cells by immunofluorescence assay and on the cytotoxicity of OHP by MTT assay.

RESULTSTFLC obviously enhanced the GJ function with the increasing of the TFLC concentration in the TM3 cells. Western blot and immunofluorescence assay confirmed that TFLC significantly enhanced the expression of Cx43 total protein and Cx43 expression on the membrane of the TM3 cells. MTT assay showed that at a high cell density (confluent with GJ formation), 20 microg/ml TFLC enhanced the GJ function of the TM3 cells and reduced the cytotoxicity of OHP (P < 0.05), while at a low density (preconfluent with no GJ formation), TFLC exhibited no effect on the cytotoxicity of OHP (P > 0.05).

CONCLUSIONTFLC increases the Cx43 expression and GJ function in normal TM3 Leydig cells, and the enhancement of GJ function reduces the cytotoxicity of OHP.

Antineoplastic Agents ; toxicity ; Cell Communication ; drug effects ; physiology ; Cell Count ; Connexin 43 ; metabolism ; Flavonoids ; pharmacology ; Gap Junctions ; drug effects ; Humans ; In Vitro Techniques ; Leydig Cells ; drug effects ; ultrastructure ; Litsea ; chemistry ; Male ; Organoplatinum Compounds ; antagonists & inhibitors ; toxicity ; Proteins ; metabolism

OBJECTIVETo investigate the effect of valproate acid sodium (VPA) on gap junction intercellular communication in breast cancer Hs578T cells and explore the mechanism.

METHODSMTT assay was used to detect the cytotoxicity of VPA on Hs578T cells, and parachute assay was used to detect the effect of VPA on dye spread of the cells. Western blotting was employed to detect the expression changes of Cx43 total protein in VPA-treated Hs578T cells. The effect of VPA on the expression of Cx43 on the surface of Hs578T cells was examined with immunofluorescence assay.

RESULTSMTT assay showed no obvious cytotoxicity of VPA on Hs578T cells at the concentrations below 10 mmol/L. VPA below 5 mmol/L obviously increased the gap junction function in Hs578T cells (P<0.01), and significantly enhanced the expression of Cx43 total protein (P<0.01) and Cx43 expression on the surface of Hs578T cells (P<0.01).

CONCLUSIONVPA can obviously increase the gap junction function in Hs578T cells possibly by enhancing Cx43 total protein expression and Cx43 protein expression on the surface of Hs578T cells.

Breast Neoplasms ; metabolism ; Cell Communication ; drug effects ; Cell Line, Tumor ; Connexin 43 ; metabolism ; Female ; Gap Junctions ; drug effects ; Humans ; Valproic Acid ; pharmacology

OBJECTIVE: To determine the effect of human corticotrophin-releasing hormone (CRH) on the expression of connexin-43 phosphate (P-Cx43) in human myometrial smooth muscle cells (SMCs) and the function of cell gap junction intercellular communication in SMCs. METHODS: Human non-conceive myometial SMCs were cultured with different concentrations of CRH (0, 5.85, 58.5, 585 and 5850 pmol/L). Western blot was used to test P-Cx43 and Cx43 non-phosphate (NP-Cx43) of protein expression. Cell scratch was used to test cell gap junction intercellular communication opening status in human myometrial SMCs. RESULTS: Compared with the control group, the expression of P-Cx43 was higher in the CRH groups (P<0.01), and was concentration-dependent. There was no significant difference in NPCx43 between the control group and the CRH groups (P>0.05). The transmission of cell layers in the CRH groups was higher than that in the control group (P<0.01), and as the concentration of CRH increased, the time was concentration-dependent (P<0.01). CONCLUSION CRH can enhance the expression of P-Cx43 and the function of gap junction intercellular communication in the primary cultured myometrial SMCs.
Cell Communication ; drug effects ; Cells, Cultured ; Connexin 43 ; metabolism ; Corticotropin-Releasing Hormone ; pharmacology ; Female ; Gap Junctions ; drug effects ; Humans ; Myocytes, Smooth Muscle ; metabolism ; Myometrium ; cytology ; Phosphorylation ; drug effects

OBJECTIVETo investigate the effect of puerarin on interleukin (IL)-8 mRNA expression and the protein release in the co-culture of human bronchial epithelial (BEAS-2B) cells and human neutrophils.

METHODSBEAS-2B cells and neutrophills were cultured separately and co-cultured with puerarin (50, 100, and 200 μg/mL) for a predetermined time. Cytokines in culture supernatant were evaluated by protein array and IL-8 quantified by enzyme-linked immunosorbent assay (ELISA). IL-8 mRNA expression was evaluated by real-time quantitative polymerase chain reaction (real-time qPCR).

RESULTSThe co-culture of BEAS-2B cells and neutrophils exhibited synergistic effects on IL-8 mRNA expression in BEAS-2B cells, but not in neutrophils after 12 h incubation (P<0.01), as compared with that in BEAS-2B cells or neutrophils alone. IL-8 protein release in the culture supernatant was obviously elevated when BEAS-2B cells were co-cultured with human neutrophils as compared with that in the supernatant of BEAS-2B cells or neutrophils alone after incubated for 2, 6, 12, and 18 h (P<0.01). Treatment with puerarin could significantly down-regulate the expression of IL-8 mRNA in BEAS-2B cells and IL-8 release in the supernatant of the co-culture of BEAS-2B cells and neutrophils (P<0.01).

CONCLUSIONPuerarin could exhibit anti-inflammatory activity by suppressing IL-8 production from the co-culture of human bronchial epithelial cells and neutrophils.

Adult ; Bronchi ; cytology ; Cell Communication ; drug effects ; Cell Line ; Coculture Techniques ; Epithelial Cells ; cytology ; drug effects ; metabolism ; Fluorescence ; Gene Expression Regulation ; drug effects ; Humans ; Interleukin-8 ; genetics ; secretion ; Isoflavones ; pharmacology ; Neutrophils ; cytology ; drug effects ; metabolism ; RNA, Messenger ; genetics ; metabolism ; Real-Time Polymerase Chain Reaction

OBJECTIVETo determine the expression of connexin 43 (Cx43) protein and explore the functional modulation of gap junction intercellular communication in astrocytes.

METHODSCultured neonatal SD rat astrocytes were divided into normal control group, all-trans retinoic acid (ATRA) group (treated with 10 µmol/L ATRA for 24 h) and oleamide group (treated with 25 µmol/L oleamide for 2 h). Western blotting and immunofluorescence assay were used to detect total cellular Cx43 protein expression and Cx43 expression on the surface of the astrocytes, respectively. Parachute assay was used to evaluate the functional changes of gap junction intercellular communication of the astrocytes.

RESULTSCompared with the normal control cells, ATRA treatment resulted in a significantly increased expression of total Cx43 protein in the astrocytes (P<0.01), and oleamide significantly suppressed its expression (P<0.01). Similarly, ATRA obviously enhanced while oleamide suppressed Cx43 protein expression on the surface of the astrocytes. The gap junction intercellular communication of the astrocytes was enhanced by ATRA (P<0.01) and inhibited by oleamide (P<0.01).

CONCLUSIONATRA and oleamide can modulate gap junction intercellular communication of the astrocytes possibly by regulating the expression of Cx43 protein.

Animals ; Astrocytes ; metabolism ; Cell Communication ; drug effects ; Cells, Cultured ; Connexin 43 ; metabolism ; Gap Junctions ; metabolism ; Oleic Acids ; pharmacology ; Rats ; Rats, Sprague-Dawley ; Tretinoin ; pharmacology

OBJECTIVETo study the role and possible mechanisms of gap junctional intercellular communication (GJIC) involved in mesangial cell (MC) proliferation which could be inhibited by bufalin.

METHODSRat mesangial cells were cultured in vitro. The effect of bufalin on platelet-derived growth factor-BB (PDGF-BB)-induced MC proliferation was evaluated by MTT assay. The function of GJIC was detected by Lucifer Yellow scrape loading and dye transfer (SLDT). mRNA levels of Cx43, Cx45 and Cx40 were measured by RT-PCR. Intracellular calcium concentrations ([Ca(2+)]i) were examined in laser scanning confocal microscopy after loading by Fura-3/AM.

RESULTSMTT indicated that bufalin could inhibited PDGF-BB-induced MC proliferation (P<0.01). Compared with the hormal control group, PDGF-BB inhibited GJIC function, increased the expression of Cx45 and Cx40 (P<0.01) without altering the Cx43 (P>0.05) in gene level and also increased [Ca(2+)]i. However, bufalin treatment enhanced GJIC function, decreased Cx45 mRNA and Cx40 mRNA expression (P<0.01), and reduced [Ca(2+)]i (P<0.01).

CONCLUSIONSBufalin inhibits PDGF-BB-induced MC proliferation, and its possible mechanisms may be related to regulation of Cx45 and Cx40 expression in the gene level, reduction of [Ca(2+)]i and enhancement of GJIC function.

Animals ; Bufanolides ; pharmacology ; Calcium ; metabolism ; Cell Communication ; drug effects ; Cell Proliferation ; drug effects ; Cells, Cultured ; Gap Junctions ; drug effects ; Mesangial Cells ; drug effects ; physiology ; ultrastructure ; Proto-Oncogene Proteins c-sis ; pharmacology ; Rats

OBJECTIVETo observe the effects of TGF-beta on the expression of connexin43 (Cx43) and Cx43-mediated gap junctional intercellular communication (GJIC) in rat Leydig cells, and investigate the association of its effects on Leydig cells with its ability of changing GJIC.

METHODSPrimarily cultured purified Leydig cells were divided into a blank control group, a positive control group (treated with the GJIC inhibitor Carbenoxolone), and four TGF-beta1 groups (treated with TGF-beta1 at the concentration of 1, 2, 5 and 10 ng/ml, respectively, for 20 hours). The localization and expression of Cx43 were detected by immunofluorescence and Western blot, and the changes in GJIC analyzed by FRAP assay.

RESULTSCx43 was expressed as scattered bright spots in the cytoplasm and membrane of Leydig cells. TGF-beta1 significantly elevated the expression of Cx43 in the cytoplasm, but caused no evident change in the membrane. Western blot showed an evident increase in the phosphorylation of Cx43 with the increased concentration of TGF-beta1 as compared with that of the blank control group (P < 0.05). After 20 hours of treatment with TGF-beta1 at 5 ng/ml, the fluorescence intensity of Leydig cells was markedly reduced (P < 0.01), with a mean fluorescence recovery rate of merely (43.58 +/- 1.87)%.

CONCLUSIONTGF-beta1 could significantly down-regulate GJIC between adjacent Leydig cells, and this inhibitory effect may be achieved by promoting the expression of Cx43 in the cytoplasm and elevating the phosphorylation of Cx43.

Animals ; Cell Communication ; drug effects ; Cells, Cultured ; Connexin 43 ; metabolism ; Gap Junctions ; drug effects ; metabolism ; Leydig Cells ; drug effects ; metabolism ; Male ; Phosphorylation ; Rats ; Transforming Growth Factor beta1 ; pharmacology

OBJECTIVETo investigate the protective effect of ginsenoside Re on myocardial cells of neonatal SD rat with hypoxia injury, and to explore its mechanism.

METHODSThe primary passage of myocardial cells collected from neonatal SD rats were divided into A group (with ordinary treatment), B group [exposed to hypoxia (1% O2, 5% CO2, 94% N(2)) for 12 hours after being cultured for 48 hours], C group (pretreated with 80 g/L ginsenoside Re for 30 minutes after 48 hours of ordinary culture, then exposed to hypoxia for 12 hours), D group (received the same treatment as used in C group except for using 40 g/L ginsenoside Re), E group (received the same treatment as used in C group except for using 20 g/L ginsenoside Re) according to the random number table, with 6 samples in each group. Myocardial cell supernatants were collected for determination of content of lactate dehydrogenase (LDH) with enzyme linked immunosorbent assay. Fluorescence recovery after photobleaching technique was used to detect gap junction intercellular communication (GJIC). Result was observed by laser scanning confocal microscope. Data were processed with paired t test.

RESULTS(1) Compared with that in B group [(403 ± 22) U/L], contents of LDH in E, D, and C groups were obviously decreased [(255 ± 16), (241 ± 13), (237 ± 24) U/L, with t value respectively 5.1, 5.2, 8.3, P values all below 0.05]. (2) The fluorescence recovery rate in A group was (74.8 ± 3.6)% 10 min after quenching, which was higher than that in B group [(13.2 ± 5.6)%, t = 15.2, P < 0.01]. The fluorescence recovery rate in C, D, and E groups was respectively (39.5 ± 2.9)%, (36.2 ± 3.1)%, and (34.3 ± 3.9)% 10 min after quenching, all higher than that in B group (with t value respectively -6.6, -41.9, 18.3, P values all below 0.05).

CONCLUSIONSGinsenoside Re pretreatment, particularly with a dose of 20 g/L, can protect myocardial cells from hypoxia injury, and the effect may be attributable to inhibition of release of LDH and improvement of the GJIC function.

Animals ; Cell Communication ; drug effects ; Cell Hypoxia ; drug effects ; Cells, Cultured ; Gap Junctions ; drug effects ; metabolism ; Ginsenosides ; pharmacology ; L-Lactate Dehydrogenase ; metabolism ; Myocytes, Cardiac ; drug effects ; metabolism ; Rats ; Rats, Sprague-Dawley