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Journal of Lipid Research, Vol 26, 1455-1463, Copyright © 1985 by Lipid Research, Inc.
WR Hitchener and RJ Cenedella
All cells of the avascular ocular lens derive from a monolayer of
epithelial cells located on only the anterior surface of this organ. The
source of the cholesterol required for the growth and division of these
cells was studied by using cultures of bovine lens epithelial cells. Cells
were in active growth during the third to fourth day of subculture
following seeding. Absolute rates of cholesterol synthesis were estimated
for the cultured cells from incorporation of [3H]water. Rates were
estimated on the assumption that 0.81 atoms of 3H of [3H]water were
incorporated into cholesterol per carbon atom of cholesterol, a situation
where all of the NADPH would be generated by oxidative enzymatic processes.
We tested this assumption by measuring the changes in sterol mass per dish
of cells grown in lipoprotein- deficient media over day 3 to 4 of
subculture and by simultaneously measuring the rates of incorporation of
[3H]water into sterols during this period. In this situation, the increases
in sterol mass should be attributable solely to de novo sterol synthesis.
We calculated that an average of 0.79 atoms of 3H of [3H]water were
incorporated by these cells into cholesterol per carbon atom of
cholesterol. Sterol synthesis was only modestly decreased (about 30%) when
the cells were cultured in media prepared with whole calf serum. Growth
rates of the cells were also little affected by the absence of
lipoproteins. In spite of the capacity to furnish its sterol requirements
by de novo synthesis, the lens epithelial cells readily degraded
125I-labeled bovine LDL, and LDL greatly decreased sterol synthesis when
added to the media at low levels.(ABSTRACT TRUNCATED AT 250 WORDS)
ARTICLES
Absolute rates of sterol synthesis estimated from [3H]water for bovine lens epithelial cells in culture
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