Related Experiment Videos
Influence of bile salts on hepatic mdr2 P-glycoprotein expression
C M Frijters1, R Ottenhoff, M J Van Wijland
1Department of Gastrointestinal and Liver Diseases, Academic Medical Center, Amsterdam, The Netherlands.
Abstract:
Mdr2 P-glycoprotein is expressed in the canalicular membrane of the mouse hepatocyte and is responsible for phospholipid secretion into bile. It is our hypothesis that it functions as a flippase in the translocation of phosphatidylcholine from the inner leaflet to the outer leaflet of the canalicular membrane. We have investigated the influence of different types of bile salts on the expression levels of mdr2 Pgp. Feeding mice a cholate-supplemented diet results in an increased mdr2 mRNA level, and this is accompanied by an increased biliary phospholipid secretion capacity. Cholate is a more hydrophobic bile salt than the main endogenous bile salt, muricholate. The induction of mdr2 gene expression and concomitant increase in phospholipid secretion are in line with the function of biliary phospholipids to inactivate the detergent action of hydrophobic bile salts.
Insights
Mice fed a cholate-supplemented diet showed increased mdr2 P-glycoprotein (Pgp) mRNA and phospholipid secretion. This suggests mdr2 Pgp
Area of Science:
- Hepatobiliary science
- Molecular biology
- Membrane transport
Background:
- Mdr2 P-glycoprotein (Pgp) in mouse hepatocytes facilitates phospholipid secretion into bile.
- This protein is hypothesized to act as a flippase for phosphatidylcholine.
- Bile phospholipids are crucial for neutralizing the detergent effects of hydrophobic bile salts.
Purpose of the Study:
- To investigate the impact of varying bile salt types on mdr2 Pgp expression levels.
- To understand the relationship between bile salt hydrophobicity and mdr2 Pgp-mediated phospholipid secretion.
Main Methods:
- Feeding mice diets supplemented with cholate, a hydrophobic bile salt.
- Measuring mdr2 mRNA levels.
- Assessing biliary phospholipid secretion capacity.
Main Results:
- Cholate-supplemented diet led to elevated mdr2 mRNA levels in mice.
- This increase in mdr2 mRNA correlated with enhanced biliary phospholipid secretion.
- The findings align with the protective role of phospholipids against hydrophobic bile salts.
Conclusions:
- Hydrophobic bile salts, like cholate, can induce mdr2 gene expression.
- Increased mdr2 Pgp expression enhances phospholipid secretion, mitigating bile salt detergent action.
- This highlights a regulatory mechanism in bile composition and hepatocyte protection.