Bile is the major route of cholesterol excretion from the body. It is concentrated in the gallbladder, and often results in supersaturation of cholesterol. The high levels of cholesterol in gallbladder bile has clinical implications with respect to cholesterol gallstone formation and cholesterolosis of the gallbladder wall. Gallbladder epithelial cells (GBEC) are exposed to high cholesterol concentrations on their apical surfaces. Therefore, GBEC are uniquely positioned to play an important role in modulating biliary cholesterol concentrations. Recently, it has been documented that the key-transporter for polarized cholesterol and phospholipid efflux in GBEC is ATP-binding cassette transporter A1 (ABCA1) and Liver X receptor (LXR) and retinoid X receptor (RXR) in the nucleus of GBEC have a role that regulates ABCA1 expression. In addition, GBEC synthesize apolipoprotein A-I and E as cholesterol acceptors. These results indicate that GBEC has a perfect system for reverse cholesterol transport. We introduce the roles and mechanisms of ABCA1, scavenger receptor class B-I, LXR and RXR related to reverse cholesterol transport in GBEC with a review of our study experience and related literature.
ATP-Binding Cassette Transporters/metabolism ; Biological Transport ; Cells, Cultured ; Cholesterol/*metabolism ; English Abstract ; Epithelium/metabolism ; Gallbladder/cytology/*metabolism ; Humans ; Receptors, Cytoplasmic and Nuclear/metabolism ; Retinoid X Receptors/metabolism