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Chloral hydrate decreases gap junction communications in rat liver epithelial cells
Citation:
Zhang, J., R. GRINDSTAFF, S. Y. THAI, S. Murray, M. J. KOHAN, AND C. F. BLACKMAN. Chloral hydrate decreases gap junction communications in rat liver epithelial cells. CELL BIOLOGY AND TOXICOLOGY. Springer, New York, NY, 27(3):207-16, (2011).
Impact/Purpose:
This manuscript was performed to define the molecular events that were responsible for the chemical-induced reduction in OJC using chloral hydrate, one ofthe chemicals in the Benane et al., 1996 study. Data in this manuscript demonstrates the decrease in OJC under chemical treatment occurs with little or no change in Cx 43 mRNA expression, but with a decrease in Cx 43 hypophosphorylation & Cx 43 protein levels.
Description:
Gap junction communication (GJC) is involved in controlling cell proliferation and differentiation. Alterations in GJC are associated with carcinogenesis, but the mechanisms involvedareunknown.Chloralhydrate(CH), a by-productofchlorinedisinfection ofwater,is carcinogenic in mice, and we demonstrated that CH reduced GJC in a rat liver epithelial cell line (Clone 9). To examine the mechanism(s) by which CH inhibits GJC, Clone 9 cells treated with CH were examined using Western blot, realtime PCR, immunocytochemical, and dyecommunication techniques. Treatment with CH (0.1-5 mM for 24hr) resulted in a dose2 of 17 dependent inhibition of GJC, as measured by Lucifer yellow dye transfer. The cells expressed both Connexin (Cx) 43 and 26, and with Western blot analysis CH (0.1-5 mM for 24hr) decreased Cx 43 protein expression at the post-transcriptional level without altering Cx 26. There was a bimodal change in Cx 43 phosphorylation as a function of CH, but a reduction in J;nRNA expression only at the higher CH levels. Similarly, with immunocytochemistry, a dosedependent decrease in Cx 43 staining at sites of cell-cell contact was apparent in CH (0.5-5 mM) treated cultures. However, a change in Cx 26 protein expression was not detected. Thus, Clone 9 cells contain at least two types of GJC channels formed by either Cx 43 or Cx 26. Understanding of the regulation of connexin may shed light on mechanisms responsible for inhibition of GJC by chemical carcinogens.
