Expression of the bile acid transport protein during liver development and in hepatoma cells

• Published in: The Journal of biological chemistry 1990-04, Vol.265 (11), p.5942-5945
• Main Authors: VON DIPPE, P, LEVY, D
• Format: Article
• Language: English
• Subjects: Aging; Analytical, structural and metabolic biochemistry; Animals; Antibodies, Monoclonal; Binding and carrier proteins; Biological and medical sciences; Biological Transport, Active; Carrier Proteins - biosynthesis; Carrier Proteins - isolation & purification; Cells, Cultured; Fetus; Fundamental and applied biological sciences. Psychology; Hydroxysteroid Dehydrogenases; Liver - embryology; Liver - growth & development; Liver - metabolism; Liver Neoplasms, Experimental - metabolism; Membrane Glycoproteins; Molecular Weight; Proteins; Rats; Rats, Inbred Strains; Taurocholic Acid - metabolism
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/S0021-9258(19)39270-1

The expression of the hepatocyte Na(+)-dependent bile acid transport protein during liver development and in hepatoma cells has been characterized using a monoclonal antibody (mAb 25D-1) which specifically recognizes this 49-kDa carrier system. mAb binding studies demonstrated a greatly reduced concentration of this transport protein on the surface of hepatoma tissue culture (HTC) cells, a result consistent with the greater than 95% reduction in bile acid transport capacity when compared with normal adult hepatocytes. Immunoprecipitation procedures with 25D-1 were utilized to quantitate the presence of this transport protein in HTC cells as well as in adult hepatocytes that had been labeled with [35S]methionine or Na125I. These studies indicate that the 49-kDa transport protein is not expressed either on the surface or in any intracellular compartment in HTC cells. mAb binding to fetal cells (day 17) also indicated a greatly decreased number of transport molecules in the plasma membrane. Total cell content of this carrier protein during the next 7 weeks of liver development, as measured by immunoprecipitation, increased in a linear fashion reaching 92% of the adult level at 4 weeks after birth, which parallels the increase in transport function. These results demonstrate that bile acid transport capacity is directly related to the level of expression of this 49-kDa membrane protein.