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CHLORAL HYDRATE DECREASES GAP JUNCTION COMMUNICATION IN RAT LIVER EPITHELIAL CELLS
Blackman, C F., R D. Grindstaff, AND J. Zhang. CHLORAL HYDRATE DECREASES GAP JUNCTION COMMUNICATION IN RAT LIVER EPITHELIAL CELLS. Presented at American Society for Cell Biology Annual Meeting, Washington, DC, 12/8-12/2001.
Chloral hydrate decreases gap junction communication in rat liver epithelial cells
Gap junction communication (GJC) is involved in controlling cell proliferation and differentiation. Connexins (Cx) that make up these junctions are composed of a closely related group of membrane proteins ranging in size from 26 kD to 56 kD. Alterations in GJC are frequently associated with cancer promotion processes, but the exact mechanism( s) of involvement is presently unknown. Chloral hydrate (CH) is found as a chlorine disinfectant by-product of raw water, and has also been found to be carcinogenic in mice. The aim of this study was to examine the mechanism by which CH treatment affects GJC in Clone 9 rat liver epithelial cells. GJC is inhibited in a dose-dependent manner (lx10-4 - 5x10-3 M) by a 24 hour treatment ofCH measured by the transfer ofa marker fluorescent dye, Lucifer yellow. Western analysis shows CH (5x 10-4M for 24 hours) decreases Connexin 43 (Cx 43) expression at the post-trans
scriptionallevel but causes no change in Connexin 26 (Cx 26) protein expression. Immunocytochemistry (ICC) shows that Cx 43 protein was abundant at membrane appositions of Clone 9 cells, and that CH (5x 10-4-5x10-3 M) decreased the anlount of Cx 43 immunoreactivity in the cell-cell contact regions of the plasma membrane; very little Cx 43 immunoreactivity was detected at the 5x10-3 M CH treatment. Subsequent studies will examine the influence of CH on Cx 43 mRNA expression, and on Cx 26 presence by ICC. Our results to date suggested that CH may inhibit GJC in Clone 9 cells by down regulation Cx 43 expression.
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Record Details:Record Type: DOCUMENT (PRESENTATION/ABSTRACT)
Organization:U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF RESEARCH AND DEVELOPMENT
NATIONAL HEALTH AND ENVIRONMENTAL EFFECTS RESEARCH LAB
ENVIRONMENTAL CARCINOGENESIS DIVISION
BIOCHEMISTRY AND PATHOBIOLOGY BRANCH