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細胞肝臟學 Cellular Hepatology

In the studies of cellular physiology of hepatocytes (liver cells), we mainly focus on the hepatobiliary secretory activities and protein sorting/targeting mechanisms. We utilize several well-differentiated hepatic cell lines that develop bile canalicular (BC) structures in culture as our cell models. By applying various fluorescent molecules as secretory markers, we are able to observe their transportation/secretion processes by confocal microscope. The movies shown below are examples of 2 different patterns of the secreted markers.

 

Secretion of a fluorescent phospholipid analog, 1,2-dimyristoyl-sn-glycero-3-phosphoethanolamine (DMPE), by the hepatoma cell line, HepG2. The fluorescent molecules were incorporated into the basolateral membrane of cells immediately after being added into the culture medium, whereas the bile canalicular membrane showed very faint signal, exhibiting a discontinuous hollow among neighboring cells. The intensity of the fluorescence signal in bile canaliculi (BC) then increased as time goes on, indicating the lipid molecules are transported to the BC domain. (Collaborated with Pei-Ling Lee in Dr. Chi-Hung Lin's lab.)

 

 

Secretion of a fluorescent organic anion, fluorescein, by HepG2. Fluorescein diacetate (FDA) was added into the culture medium and diffused through the cell membrane. In cells, FDA is then hydrolyzed by ubiquitous intracellular easterases, which subsequently produced the fluorescent anion, fluorescein. The process of the transportation can be visualized by observing the fluorescence signal within BC lumen (dark hollows). As the demonstration shown here, only a subset of BC is capable of the transportation of fluorescein. We found that the transportation ability of BCs is correlated with certain protein sorting mechanisms in liver cells (Lian et al., 1999).

 

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Updated 6/13/2013. Copyright© 2001 Jin-Wu Tsai. All rights reserved.