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Acetyl‐CoA carboxylase in reuber hepatoma cells: Variation in enzyme activity, insulin regulation, and cellular lipid content
Author(s) -
Bianchi Antonella,
Evans Joseph L.,
Nordlund AnnCharlotte,
Watts Thomas D.,
Witters Lee A.
Publication year - 1992
Publication title -
journal of cellular biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.028
H-Index - 165
eISSN - 1097-4644
pISSN - 0730-2312
DOI - 10.1002/jcb.240480113
Subject(s) - lipid metabolism , biochemistry , biology , pyruvate carboxylase , insulin , acetyl coa carboxylase , enzyme , cell culture , lipid droplet , enzyme assay , intracellular , metabolism , endocrinology , genetics
Abstract Ruber hapatoma cells are useful cultured lines for the study of insulin action, lipid and lipoprotein metabolism, and the regulation of acetyl‐CoA carboxylase (ACC), the rate‐limiting enzyme of faty acid biosynthesis. During investigations in deifferent clonal lines of these of these cells, we have uncovered marked intercellular variability in the activity, enzyme content, and insulin regulation of ACC paralleled by differences in cellular neutral lipid (triglyceride) content. Two contrasting clonal liners, Fao and H356A‐1, have been studied in detail. Several features distinguish these two lines, including differences in ACC activity and enzyme kinetics, the content of the two major hepatic ACC isozymes (M, 280,000 and 265,000 Da) and their heteroisozymic complex, the extent of ACC phosphorylation, and the ability of ACC to be activated on stimulation by insulin and insulinomimetic agonists. As studied by Nile Red staining and fluorscence‐activated cell sorting, these two lines also display marked differences in neutral lipid content, which correlates with both basal levels of ACC activity and inhobition of ACC by the fatty acid analog, 5‐(tetradecyloxy)‐2‐furoic and (TOFA). Thsese results emphasize the importance of characterization of any particular clonal line of Reuber cells for studies of enzyme regulation, substrate metabolism, and hormone action. With respect to ACC, studies in contrasting colonal lines of Ruber cells could provide valuable clues to understanding both the complex mechanisms of intracellular ACC regulation in the absence and presence of hormones and its regulatory role (s) in overla hepatic lipid metabolism.