The effect of Bisphenol A on the gap junction-mediated intercellular communication among cultured mouse macrophage cells (92.5)

Abstract

Abstract There has been a number of evidence that macrophages establish direct intercellular communication through connexin-forming gap junction channels. In the present study the effect of bisphenol A (BPA), a potent endocrine disruptor, on the gap junction-mediated intercellular communication (GJIC) among cultured mouse macrophage cells (J774 cell-line) was characterized. In J774 cells connexin43 is expressed as a major channel-forming protein. BPA has been described as a xenoestrogen, and detected in human serum and amniotic fluid. The cytotoxicity of BPA toward the cultured cells was evaluated by using both MTT reduction and LDH leakage assay systems. The results showed no appreciable loss in cell viability in the presence of increasing concentrations of BPA (from 0.1 to 3.2 μM) for 1 hr incubation. However, most of cell viability was lost when cells were incubated for 24 hr with the same concentrations of BPA. The BPA acted as an antagonist on GJIC among the cultured macrophage cells, and the phenomenon was dose-dependent and irreversible. According to the data obtained from scrape-loading dye-transfer experiments, three quarters of normal GJIC was reduced by concentration of 0.4 μM BPA for 1 hr incubation. To identify the relevance of this retardation upon BPA treatment, the mRNA and protein levels of Cx43 were assessed with RT-PCR and Western-blotting, respectively. The total protein level of Cx43 was almost constant in a wide range of BPA concentrations, as well as in Cx43 mRNA level. These results suggest that BPA inhibits GJIC through a modulation of the gating of gap junction channels, not through a genomic modulation of Cx43 in macrophage cells. [This study was supported by Korea Research Foundation Grant 041-D00192]